.•'Un'itid States?
-' ", t-" ''<*•• • •••" -
-------
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PWB Engineering Support Team
The PWB Engineering Support Team consisted of University of Tennessee faculty and
graduate students who developed analytical models for the project and/or authored sections of
this document. Members of the Team and the sections to which they contributed are listed
below:
Exposure Assessment and Risk Characterization
Dr. Chris D. Cox, Associate Professor of Civil and Environmental Engineering
Nicholas D. Jackson, M.S. Candidate, Civil and Environmental Engineering
Dr. R. Bruce Robinson, Professor of Civil and Environmental Engineering
Cost Analysis
Dr. Rupy Sawhney, Assistant Professor of Industrial Engineering and Director, Lean Production
Laboratory
Disclaimer
Some information in this document was provided by individual technology vendors and
has not been independently corroborated by EPA. The use of specific trade names or the
identification of specific products or processes in this document are not intended to represent an
endorsement by the EPA or the U.S. Government. Discussion of federal environmental statutes
is intended for information purposes only; this is not an official guidance document, and should
not be relied on by companies in the printed wiring board industry to determine applicable
regulatory requirements.
-------
For More Information
To learn more about the Design for the Environment Printed Wiring Board Project, or to
obtain other related materials, please contact:
Pollution Prevention Information Clearinghouse (PPIC)
U.S. Environmental Protection Agency
401 M Street, S.W. (7409)
Washington, DC 20460
Phone: (202)260-1023
Fax: (202)260-4659
E-mail: ppic@epamail.epa.gov
website: www. epa.gov/opptintr/library/libppic.htm
Or visit the Design for the Environment Printed Wiring Board Project Web site at:
http://www.ipc. org/html/ehstypes.htm#design
For more information about the Design for the Environment Program, visit the Design for
the Environment Program Web site at:
http ://www. epa. gov/dfe
The web site also contains the document, Cleaner Technology Substitutes Assessment: A
Methodology and Resources Guide, which describes the basic methodology used in this
assessment.
To learn more about the University of Tennessee Center for Clean Products and Clean
Technologies, visit the Center's Web site at:
http://eerc.ra.utk.edu/clean/
11
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Acknowledgments
This document was prepared by the University of Tennessee (UT) Knoxville Center for
Clean Products and Clean Technologies and the PWB Engineering Support Team with assistance
from numerous UT students and staff. The authors would like to acknowledge the outstanding
contributions of Chad Toney, Nayef Alteneh, Scott Brown, Sittichai Leftwattanarak and
Yatesh Midha, M.S. Candidates in Industrial Engineering, who helped design and perform the
cost analysis in Section 4.2; Catherine Wilt, UT Center for Clean Products and Clean
Technologies, who researched and wrote the Regulatory Status section (Section 4.3); and
Margaret Goergen, UT Center for Clean Products and Clean Technologies, who was the
document production manager.
Valuable contributions to the project were provided by the project's Core Group
members, including: Kathy Hart, EPA Project Lead and Core Group Co-Chair; Christopher
Rhodes, Institute for Interconnecting and Packaging Electronic Circuits, Core Group Co-Chair;
Debbie Boger, EPA Technical Lead and Technical Workgroup Co-Chair; John Lott, DuPont
Electronics, Technical Workgroup Co-Chair; Michael Kerr, Circuit Center, Inc.,
Communication Workgroup Co-Chair; Gary Roper, Substrate Technologies, Inc.,
Implementation Workgroup Co-Chair; Greg Pitts, Microelectronics and Computer Technology
Corporation; John Sharp, Teradyne Connection Systems; Steve Bold, Continental Circuits
Corporation; and Ted Smith, Silicon Valley Toxics Coalition.
We would like to acknowledge Bill Birch of PWB Interconnect Solutions, Inc., and
Susan Mansilla of Robisan Laboratory, Inc., for their work in planning, conducting testing for,
and writing a technical paper presenting the results of the making holes conductive performance
demonstration. Recognition is also given to ADI/Isola who supplied the materials for the
performance demonstration, and to H-R Industries, Inc. and Hadco Corporation for
volunteering their facilities to build and electroplate the boards. Performance demonstration
contractor support was provided by Abt Associates, Inc., of Cambridge, MA, under the direction
of Cheryl Keenan.
The following members of the U.S. Environmental Protection Agency (EPA) Design for
the Environment (DfE) Staff and the EPA Workgroup provided direction and staff support for
this project.
EPA Design for the Environment Staff
Kathy Hart
Debbie Boger
Dipti Singh
Bill Hanson
Joe Breen
111
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EPA Risk Management Workgroup
We would like to express appreciation to the EPA Risk Management Workgroup, who
provided valuable expertise in the development of the CTSA and provided comments on project
documents.
Sid Abel
Susan Dillman
Gail Froiman
Susan Krueger
Dave Mauriello
Terry O'Bryan
Daljit Sawhney
John Shoaff
Tracy Williamson
Participating Suppliers
We would like to thank the suppliers for their participation in the Design for the
Environment Printed Wiring Board Project. In addition to supplying critical information
regarding the various technologies, these companies also made significant contributions in
planning and conducting the performance demonstration. The participating suppliers are listed
below.
Atotech U.S.A., Inc.
Mike Boyle
1750 Overview Drive
Rock Hill, SC 29731-2000
Phone: (803)817-3500
Electrochemicals, Inc.
Michael Carano
5630 Pioneer Creek Drive
Maple Plain, MN 55359
Phone: (612)479-2008
Enthone-OMI, Inc.
Kathy Nargi-Toth
P.O. Box 1900
New Haven, CT 06508
Phone: (203)932-8635
LeaRonal, Inc.
Denis Morrissy
272 Buffalo Avenue
Freeport, NY11520
Phone: (516) 868-8800
MacDermid, Inc.
Mike Wood
245 Freight Street
Waterbury, CT 06702
Phone: (203)575-5700
Shipley Company
Martin Bayes
455 Forest Street
Marlborough, MA 01752
Phone: (508)229-7263
Solution Technology Systems
Eric Harnden
112 First Street
Redlands, CA 92373
Phone: (909)793-9493
W.R. Grace and Company
David Peard
55 Hayden Avenue
Lexington, MA 02173
Phone: (617) 861-6600, ext. 2704
IV
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Performance Demonstration Sites
We would like to recognize the twenty-six test sites that volunteered the use of their
facilities for the performance demonstration, and thank them for their commitments of resources
and time. We also appreciate the assistance they provided in gathering data necessary for the
preparation of this document.
Altron, Inc.
Bureau of Engraving, Inc.
Circuit Connect, Inc.
Circuit Science, Inc.
Circuit Center, Inc.
Cray Research, Inc.
Details, Inc.
Dynacircuits Manufacturing Co.
Electronic Service and Design
GCI, Inc.
GE Fanuc Automation
Graphic Products, Inc.
Greule GmbH
Hadco Corporation
LeaRonal, Inc.
M-Tek/Mass Design, Inc.
MacDermid, Inc.
Metalex GmbH
Nicolitch S.A.
Omni-Circuits, Inc.
Poly Print GmbH
Pronto Circuit Technologies
Sanmina Corporation
Schoeller & Co. Elektronik GmbH
Sigma Circuits, Inc.
Texas Instruments Printed Circuit Resources
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Technical Workgroup
We appreciate the industry representatives and other interested parties who participated in
the Printed Wiring Board Project Technical Workgroup, and provided comments on the
individual modules of the CIS A. Many thanks to the members of this workgroup for their
voluntary commitments to this project.
Martin Bayes
Shipley Company
Bill Birch
PWB Interconnect Solutions, Inc.
Robert Boguski, Jr.
Apogee Engineering, Inc.
Mike Boyle
Atotech U.S.A., Inc.
Eric Brooman
Concurrent Technologies Corporation
Michael Carano
Electrochemicals, Inc.
Thomas Carroll
Hughes Aircraft Company
Alan Cash
Northrop Grumman Corporation
Nitin Desai
Motorola, Inc.
David Di Margo
Phibro-Tech, Inc.
Bernard Ecker
Teledyne Systems Company
Phil Edelstein
Phibro-Tech, Inc.
Ted Edwards
Honeywell, Inc.
Elahe Enssani
San Francisco State University
College of Science and Engineering
Frederick Fehrer
Consultant
Chris Ford
Printed Circuit Corporation
Joan Girard
Electrotek Corporation
Eric Harnden
Solution Technology Systems
John Howard
California Occupational Safety and Health
Agency
H. Martin Jessen
U.S. Filter Recovery Services
Greg Karras
Communities for a Better Environment
Michael Kerr
Circuit Center, Inc.
John Lott
DuPont Electronics
Jim Martin
LeaRonal, Inc.
C. Al McPherson
Motorola, Inc.
VI
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Peter Moleux
Peter Moleux P.E. and Associates
Damn Moore
Raytheon Company
John Mukhar
City of San Jose Environmental Services
Suzanne Nachbor
Honeywell, Inc.
KathyNargi-Toth
Enthone-OMI, Inc.
David Peard
W.R. Grace and Company
Greg Pitts
Microelectronics and Computer Technology
Corporation
Mostafa Pournejat
Zycon Corporation
Neal Preimesburger
Hughes Aircraft Company
Christopher Rhodes
Institute for Interconnecting and Packaging
Electronic Circuits
Ted Smith
Silicon Valley Toxics Coalition
Evan Sworzyn
Teledyne Systems Company
C. Edwin Thorn
Electrochemicals, Inc.
Jane Tran
Orange County Sanitation District
Russ Tremblay
M/A-COM,Inc.
Laura Turbini
Georgia Institute of Technology
Materials Science and Engineering
Phil Van Buren
Sandia National Laboratories
Lee Wilmot
Hadco Corporation
Mike Wood
MacDermid, Inc.
James Zollo
Motorola, Inc.
Gary Roper
Substrate Technologies, Inc.
Tim Scott
Advanced Quick Circuits
John Sharp
Teradyne Connection Systems
Jodie Siegel
University of Massachusetts
Toxics Use Reduction Institute
Vll
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Table of Contents
Page
Executive Summary ... T-JO i
J ' ' ' , Jtio-1
Chapter 1
Introduction , ,
1.1 Project Background j_2
1.1.1 EPADfEProgram 1-2
1.1.2 DfE Printed Wiring Board Project 1-2
1.2 Overview of PWB Industry 1-4
1.2.1 Types of Printed Wiring Boards 1_4
1.2.2 Industry Profile '.'.'.'.'.'.'.'.'. 1-4
1.2.3 Overview of Rigid Multi-Layer PWB Manufacturing 1.5
1.3 CTSA Methodology " j_?
1.3.1 Identification of Alternatives and Selection of Project Baseline 1-7
1.3.2 Boundaries of the Evaluation l_g
1.3.3 Issues Evaluated j_9
1.3.4 Primary Data Sources J_JQ
1.3.5 Project Limitations 1_12
1.4 Organization of This Report 1_14
References , ,-
Chapter 2
Profile of the Making Holes Conductive Use Cluster 2-1
2.1 Chemistry and Process Description of MHC Technologies '.'.'.'.'.'. 2-1
2.1.1 Substitutes Tree of MHC Technologies '..'.'.'.'.'" 2-1
2.1.2 Overview of MHC Technologies 2-3
2.1.3 Chemistry and Process Descriptions of MHC Technologies 2-4
2.1.4 Chemical Characterization of MHC Technologies 2-18
2.2 Additional MHC Technologies 2-24
2.2.1 Lomerson Process 2-24
2.2.2 Non-Formaldehyde Electroless Nickel 2-24
2.3 Market Profile of MHC Technologies '.'.'.'.'.'.'.'.'.'.'.'. .'.'.""•" 2-26
References 2_27
Chapter 3
Risk -i
3.1 Source Release Assessment 3_j
3.1.1 Data Sources and Assumptions 3_2
3.1.2 Overall Material Balance for MHC Technologies 3-3
3.1.3 Source and Release Information For Specific MHC Technology
Categories 3_jg
3.1.4 Uncertainties in the Source Release Assessment 3-31
3.2 Exposure Assessment 3_32
3.2.1 Exposure Setting . 3_32
viii
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3.2.2 Selection of Exposure Pathways 3~38
3.2.3 Exposure-Point Concentrations 3-40
3.2.4 Exposure Parameters and Potential Dose Rate Models 3-49
3.2.5 Uncertainty and Variability 3-63
3.2.6 Summary • 3'65
3.3 Human Health and Ecological Hazards Summary 5-68
3.3.1 Carcinogenicity • 3"70
3.3.2 Chronic Effects (Other than Carcinogenicity) 3-72
3.3.3 Ecological Hazard Summary 3~88
3.3.4 Summary 3'98
3.4 Risk Characterization • 3-100
3.4.1 Summary of Exposure Assessment 3-100
3.4.2 Summary of Human Health Hazards Assessment 3-106
3.4.3 Methods Used to Calculate Human Health Risks S-106
3.4.4 Results of Calculating Risk Indicators 3-109
3.4.5 Uncertainties 3-122
3.4.6 Conclusions • 3-123
3.5 Process Safety Assessment 3-129
3.5.1 Chemical Safety Concerns 3-129
3.5.2 Corrosive, Oxidizer, and Reactive MHC Chemical Products 3-131
3.5.3 MHC Chemical Product Health Hazards 3~133
3.5.4 Other Chemical Hazards 3-136
355 Process Safety Concerns 3-137
^141
References J"1^1
Chapter 4
Competitiveness >
4.1 Performance Demonstration Results 4-1
4.1.1 Background 4-1
4.1.2 Performance Demonstration Methodology 4-1
4.1.3 Test Vehicle Design 4-3
4.1.4 Electrical and Microsection Testing Methodology 4-3
4.1.5 Results 4-5
4.1.6 Comparison of Microsection and 1ST Test Results 4-21
4.2 Cost Analysis 4-23
4.2.1 Overview of the Cost Methodology 4-25
4.2.2 Simulation Results 4-39
4.2.3 Cost Formulation Details and Sample Calculations 4-40
4.2.4 Results 4-52
4.2.5 Sensitivity Analysis • 4-55
4.2.6 Conclusions • 4-57
4.3 Regulatory Status 4'58
4.3.1 Clean Water Act 4"58
4.3.2 Safe Drinking Water Act 4-61
4.3.3 Clean Air Act 4~62
4.3.4 Resource Conservation and Recovery Act 4-64
IX
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4.3.5 Comprehensive Environmental Response, Compensation and
Liability Act 4_67
4.3.6 Superfund Amendments and Reauthorization Act and
Emergency Planning and Community Right-To-Know Act 4-68
4.3.7 Toxic Substances Control Act 4.59
4.3.8 Occupational Safety and Health Act 4.71
4.3.9 Summary of Regulations by MHC Technology 4-71
4.4 International Information 4_8 j
4.4.1 World Market for PWBs :..'.'.'.'.'.'].'.'.' 4-81
4.4.2 International Use of MHC Alternatives 4_8i
4.4.3 Regulatory Framework 4_83
4.4.4 Conclusions 4_g4
References 4 85
Chapter 5
Conservation ^ ,
5.1 Resource Conservation 5_j
5.1.1 Natural Resource Consumption 5_1
5.1.2 Conclusions 5_g
5.2 Energy Impacts 5_9
5.2.1 Energy Consumption During MHC Process Operation 5.9
5.2.2 Energy Consumption Environmental Impacts 5_14
5.2.3 Energy Consumption in Other Life-Cycle Stages 5-17
5.2.4 Conclusions 5_17
References 5 19
Chapter 6
Additional Environmental Improvement Opportunities 6_1
6.1 Pollution Prevention g_2
6.1.1 Management and Personnel Practices 6-3
6.1.2 Materials Management and Inventory Control 6-5
6.1.3 Process Improvements 6_g
6.2 Recycle, Recovery, and Control Technologies Assessment 6-17
6.2.1 Recycle and Resource Recovery Opportunities 6-17
6.2.2 Control Technologies 6_2i
References ; ' ' < o/r
o-zo
Chapter 7
Choosing Among MHC Technologies 7_j
7.1 Risk, Competitiveness, and Conservation Data Summary 7-2
7.1.1 Risk Summary 7_2
7.1.2 Competitiveness Summary 7-11
7.1.3 Resource Conservation Summary 7_17
7.2 Social Benefits/Costs Assessment 7.19
7.2.1 Introduction to Social Benefits/Costs Assessment 7-19
7.2.2 Benefits/Costs Methodology and Data Availability 7-21
7.2.3 Private Benefits and Costs 7_22
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7.3
References
7.2.4 External Benefits and Costs 7-28
7.2.5 Summary of Benefits and Costs • • 7-36
Technology Summary Profiles 7-39
7.3.1 Electroless Copper Technology . . . 7-39
7.3.2 Carbon Technology 7-44
7.3.3 Conductive Polymer Technology . . . . ; 7-46
7.3.4 Graphite Technology • • • 7-49
7.3.5 Non-Formaldehyde Electroless Copper Technology 7-51
7.3.6 Organic-Palladium Technology 7-54
7.3.7 Tin-Palladium Technology 7-57
7-61
Volume II
Appendix A Data Collection Sheets
Appendix B Publicly-Available Bath Chemistry Data
Appendix C Chemical Properties Data
Appendix D Supplemental Exposure Assessment Information
Appendix E Comprehensive Exposure Assessment and Risk Characterization Results
Appendix F Supplemental Performance Demonstration Information
Appendix G Supplemental Cost Analysis Information
Appendix H H2P Computer Printouts: Pollutants Generated by Energy Production
XI
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LIST OF TABLES
Table 1.1 MHC Technologies Submitted by Chemical Suppliers .............. 1_H
Table 1.2 Responses to the Workplace Practices Questionnaire ........... ...... 1-12
Table 2.1 Non-Proprietary Chemicals and Associated MHC Technologies . . . . . ... 2-19
Table 2.2 Material Safety Data Sheet Trade Secret Information ........... ..... 2-22
Table 2.3 Market Value of PWB and Electroless Copper Chemicals ... ............ 2-26
Table 3.1 Water Usage of MHC Technologies .................... ' .' " | ...... 3_6
Table 3.2 Average Bath Dimensions and Temperatures for All Processes .'.'.'.'.'.'.'.'.'.'.'. 3-7
Table 3.3 Spent Bath Treatment and Disposal Methods ................... ..... 3_H
Table 3 .4 Treatment and Discharge Methods and Copper Concentration Summarized
from Pollution Prevention and Control Survey ..................... 3. 12
Table 3.5 Sludge Generation from Wastewater Treatment of MHC Line Effluents ____ 3-15
Table 3.6 Workplace Activities and Associated Potential Exposure Pathways ____ .... 3-39
Table 3.7 Potential Population Exposure Pathways ........................ 3-40
Table 3.8 Summary of Federal OSHA Monitoring Data for PWB Manufacturers ......
(SIC 3672).... .................................... 3_41
Table 3.9 Results of Workplace Air Modeling ........................ 3_42
Tables. 10 Results of Ambient Air Modeling ........................ ........ 3_48
Table 3.11 Duration and Frequency of Chemical Bath Sampling ...... '.'.'.'.'.'.'.'.'.'.'.'.'. 3-50
Table 3.12 Duration and Frequency of Chemical Additions .............. .... 3-50
Table 3.13 Duration of Chemical Bath Replacement ................... ........ 3_50
Table 3.14 Frequency of Chemical Bath Replacement for Conveyorized Processes . . . . 3-5 1
Table 3.15 Filter Replacement ........................ 3_52
Table 3.16 Duration of Working in the Process Area .................... '.'.'."'' 3-52
Table 3.17 Parameter Values for Daily Workplace Inhalation Exposures ............ 3-53
Table 3. 18 Parameter Values for Daily Workplace Dermal Exposures .......... .... 3-54
Table 3. 19 Parameter Values for Estimating Average Workplace Exposures 3-56
Table 3.20 Estimated Average Daily Dose (ADD) for Workplace Exposure - .........
Inhalation and Dermal ............................ 3_57
Table 3.21 Parameter Values for Estimating Nearby Residential Inhalation Exposure 3-62
Table 3 .22 Estimated Average Daily Dose (ADD) for General Population Inhalation
Exposure ................................... 3_g3
Table 3.23 Known Use Cluster Chemicals and Associated MHC Process ............ 3-68
Table 3.24 Available Carcinogenicity Information .................. ....... 3_71
Table 3.25 Summary of RfC and RfD Information ....... 3 73
Table 3.26 NOAEL/LOAEL Values ............ ...................... ...... 3^74
Table 3.27 Summary of Health Effects Information .................. ' ..... 3.73
Table 3.28 Summary of EPA Structure- Activity Team Results for Proprietary ........
Chemicals ..................................... 3_8Q
Table 3.29 Available Toxicity Data for Non-Proprietary Chemicals ........... . . . ' . 3-80
Table 3.30 Developmental Hazards Summary ........................ ' ...... 3_83
Table 3.31 Aquatic Toxicity Information ..................... 3_gg
Table 3.32 Estimated Ecological (Aquatic) Toxicity Information for Non-Proprietary
Chemicals
Xll
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Table 3.33 Aquatic Hazard Concern Concentrations (CCs) and Hazard Concern
Levels by MHC Technology for Non-Proprietary Chemicals 3-95
Table 3.34 Summary of Aquatic, Toxicity for Proprietary Chemicals 3-98
Table 3.35 Absorption Percentages 3-108
Table 3.36 Summary of Human Health Risk Results From Inhalation Exposure for
Selected Non-Proprietary Chemicals . 3-113
Table 3.37 Summary of Human Health Risk Results From Inhalation Exposure for
Selected Proprietary Chemicals 3-116
Table 3.38 Summary of Human Health Risk Results From Dermal Exposure for
Selected Non-Proprietary Chemicals 3-117
Table 3.39 Summary of Human Health Risk Results From Dermal Exposure for
Selected Proprietary Chemicals 3-119
Table 3.40 Flammable, Combustible, Explosive, and Fire Hazard Possibilities
for MHC Processes 3-130
Table 3.41 Corrosive, Oxidizer, Reactive, Unstable, and Sudden Release of Pressure
Possibilities for MHC Processes . 3-132
Table 3.42 Sensitizer, Acute and Chronic Health Hazards, and Irreversible Eye
Damage Possibilities for MHC Processes 3-134
Table 4.1 Defective Coupons Found at Prescreening 4-6
Table 4.2 Mean Post Circuit Resistance Measurements, in Milliohms 4-7
Table 4.3 Mean PTH Circuit Resistance Measurements, in Milliohms 4-7
Table 4.4 Prescreening Results - 0.013" Vias for All Test Sites 4-8
Table 4.5 Correlation of MHC Technologies with Test Site Numbers 4-9
Table 4.6 Proportion of Panels Exhibiting Defects , 4-10
Table 4.7 Microsection Copper Plating Thickness 4-11
Table 4.8 Mean 1ST Cycles to Failure, by Test Site 4-12
Table 4.9 Mean 1ST Cycles to Failure, by MHC Technology 4-12
Table 4.10 Mean Resistance Degradation of Post Interconnect, by Test Site 4-17
Table 4.11 Mean Resistance Degradation of Post Interconnect, by MHC Technology . . 4-17
Table 4.12 IST/Microsection Data Correlation 4-22
Table 4.13 MHC Processes Evaluated in the Cost Analysis 4-23
Table 4.14 Cost Components 4-28
Table 4.15 Number of Filter Replacements by MHC Process 4-31
Table 4.16 Bath Volumes Used for Conveyorized Processes - 4-33
Table 4.17 Time-Related Input Values for Non-Conveyorized Processes 4-34
Table 4.18 Time-Related Input Values for Conveyorized Processes 4-34
Table 4.19 Bath Replacement Criteria for Electroless Copper Processes 4-35
Table 4.20 BOAs for Transportation of Chemicals to MHC Line 4-37
Table 4.21 Costs of Critical Tasks 4-38
Table 4.22 Example Simulation Output for Non-Conveyorized Electroless Copper
Process: Frequency and Duration of Bath Replacements 4-39
Table 4.23 Production Time and Down Time for MHC Processes to Produce
350,000 ssf 4-40
Table 4.24 Chemical Cost per Bath Replacement for One Supplier of the
Non-Conveyorized Electroless Copper Process 4-45
Table 4.25 Materials Cost for the Non-Conveyorized Electroless Copper Process 4-45
Table 4.26 Tiered Cost Scale for Monthly Wastewater Discharges to a POTW 4-48
xiii
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Table 4.27 Summary of Costs for the Non-Conveyorized Electroless Copper Process 4-52
Table 4.28 Total Cost of MHC Alternatives 4.53
Table 4.29 MHC Alternative Unit Costs 4-55
Table 4.30 CWA Regulations That May Apply to Chemicals in MHC Technologies 4-59
Table 4.31 PWB Pretreatment Standards Applicable to Copper 4-61
Table 4.32 SWDA Regulations That May Apply to Chemicals in MHC Technologies . . 4-62
Table 4.33 CAA Regulations That May Apply to Chemicals in MHC Technologies 4-63
Table 4.34 RCRA Hazardous Waste Codes That May Apply to Chemical Wastes
From MHC Technologies 4_65
Table 4.35 CERCLA Reportable Quantities That May Apply to Chemicals in MHC
Technologies 4-67
Table 4.36 SARA and EPCRA Regulations That May Apply to Chemicals in MHC
Technologies 4_6g
Table 4.37 TSCA Regulations That May Apply to Chemicals in MHC Technologies . . . 4-70
Table 4.38 Summary of Regulations That May Apply to Chemicals in the
Electroless Copper Technology 4_72
Table 4.39 Summary of Regulations That May Apply to Chemicals in the
Carbon Technology 4-74
Table 4.40 Summary of Regulations That May Apply to Chemicals in the
Conductive Ink Technology 4_75
Table 4.41 Summary of Regulations That May Apply to Chemicals in the
Conductive Polymer Technology 4_76
Table 4.42 Summary of Regulations That May Apply to Chemicals in the
Graphite Technology 4.77
Table 4.43 Summary of Regulations That May Apply to Chemicals in the
Non-Formaldehyde Electroless Copper Technology 4-78
Table 4.44 Summary of Regulations That May Apply to Chemicals in the
Organic-Palladium Technology 4.79
Table 4.45 Summary of Regulations That May Apply to Chemicals in the
Tin-Palladium Technology 4_80
Table 5.1 Effects of MHC Alternatives on Resource Consumption 5-2
Table 5.2 Rinse Water Flow Rates for MHC Process Alternatives 5-4
Table 5.3 Total Rinse Water Consumed by MHC Process Alternatives by
Board Production Rate 5.5
Table 5.4 Energy-Consuming Equipment Used in MHC Process Lines 5-10
Table 5.5 Number of MHC Process Stages that Consume Energy by Function of
Equipment 5_1 j
Table 5.6 Energy Consumption Rates for MHC Equipment 5-12
Table 5.7 Hourly Energy Consumption Rates for MHC Alternatives 5-13
Table 5.8 Energy Consumption Rate per ssf of Board Produced for MHC
Alternatives 5_14
Table 5.9 Pollution Resulting From the Generation of Energy Consumed by MHC
Technologies 5_jg
Table 5.10 Pollutant Environmental and Human Health Concerns 5-17
Table 6.1 Management and Personnel Practices Promoting Pollution Prevention 6-3
Table 6.2 Materials Management and Inventory Control Pollution Prevention Practices . 6-5
Table 6.3 Pollution Prevention Practices to Reduce Bath Contaminants . . . 6-7
xiv
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Table 6.4 Methods for Reducing Chemical Bath Drag-Out 6-9
Table 6.5 Bath Maintenance Improvement Methods to Extend Bath Life 6-10
Table 6.6 Treatment Chemicals Used to Remove Heavy Metals from Chelated
Wastewater . 6-23
Table 7.1 MHC Processes Evaluated in the CTSA 7-1
Table 7.2 MHC Chemicals of Concern for Potential Occupational Inhalation Risk 7-5
Table 7.3 MHC Chemicals of Concern for Potential Occupational Dermal Risk 7-5
Table 7.4 Aquatic Hazard Data . . . . . . 7-8
Table 7.5 Hazardous Properties of MHC Chemical Products 7-9
Table 7.6 Cost of MHC Technologies 7-13
Table 7.7 Regulatory Status of MHC Technologies 7-16
Table 7.8 Energy and Water Consumption Rates of MHC Alternatives 7-17
Table 7.9 Glossary of Benefits/Costs Analysis Terms . 7-20
Table 7.10 Differences in Private Costs ..-...- 7-23
Table 7.11 Summary of Occupational Hazards, Exposures, and Risks of Potential
Concern 7-25
Table 7.12 Number of Chemicals with High Aquatic Hazard Concern Level 7-27
Table 7.13 Examples of Private Costs and Benefits Not Quantified . 7-29
Table 7.14 Potential Health Effects Associated with MHC Chemicals of Concern 7-31
Table 7.15 Estimated Willingness-to-Pay to Avoid Morbidity Effects for One
SymptomDay (1995 dollars) 7-34
Table 7.16 Energy and Water Consumption of MHC Technologies 7-35
Table 7.17 Relative Benefits and Costs of MHC Alternatives Versus Baseline 7-37
Table 7.18 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Electroless Copper Technology . .-.. 7-40
Table 7.19 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Carbon Technology 7-45
Table 7.20 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Conductive Polymer Technology 7-47
Table 7.21 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Graphite Technology 7-50
Table 7.22 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Non-Formaldehyde Electroless Copper Technology 7-52
Table 7.23 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Organic-Palladium Technology 7-55
Table 7.24 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Tin-Palladium Technology 7-58
XV
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LIST OF FIGURES
Page
Figure 1.1 Rigid, Multi-Layer PWB Manufacturing Process Flow Diagram 1-6
Figure 2.1 Substitutes Tree of MHC Technologies 2-2
Figure 2.2 Generic Process Steps for the Electroless Copper Technology 2-5
Figure 2.3 Electroless Copper Processes Submitted by Chemical Suppliers 2-6
Figure 2.4 Generic Process Steps for the Carbon Technology 2-7
Figure 2.5 Generic Process Steps for the Conductive Ink Technology 2-9
Figure 2.6 Generic Process Steps for the Conductive Polymer Technology 2-10
Figure 2.7 Generic Process Steps for the Graphite Technology 2-12
Figure 2.8 Generic Process Steps for the Non-Formaldehyde Electroless Copper
Technology 2-13
Figure 2.9 Generic Process Steps for the Organic-Palladium Technology 2-15
Figure 2.10 Generic Process Steps for the Tin-Palladium Technology 2-16
Figure 2.11 Tin-Palladium Processes Submitted by Chemical Suppliers 2-17
Figure 3.1 Schematic of Overall Material Balance for MHC Technologies 3-4
Figure 3.2 Wastewater Treatment Process Flow Diagram 3-5
Figure 3.3 Generic Electroless Copper Process Steps and Typical Bath Sequence 3-17
Figure 3.4 Generic Carbon Process Steps and Typical Bath Sequence 3-19
Figure 3.5 Generic Conductive Ink Process Steps 3-21
Figure 3.6 Generic Conductive Polymer Process Steps and Typical Bath Sequence .... 3-22
Figure 3.7 Generic Graphite Process Steps and Typical Bath Sequence 3-23
Figure 3.8 Generic Non-Formaldehyde Electroless Copper Process Steps and
Typical Bath Sequence 3-25
Figure 3.9 Generic Organic-Palladium Process Steps and Typical Bath Sequence 3-27
Figure 3.10 Generic Tin-Palladium Process Steps and Typical Bath Sequence 3-29
Figure 4.1 Electroless Copper -1ST Cycles to Fail vs. Resistance 4-13
Figure 4.2 Carbon - 1ST Cycles to Fail vs. Resistance 4-14
Figure 4.3 Graphite - 1ST Cycles to Fail vs. Resistance 4-14
Figure 4.4 Palladium - 1ST Cycles to Fail vs. Resistance 4-15
Figure 4.5 Non-Formaldehyde Electroless Copper - 1ST Cycles to Fail vs. Resistance . . 4-15
Figure 4.6 Conductive Polymer - 1ST Cycles to Fail vs. Resistance 4-16
Figure 4.7 Electroless Copper - Post Resistance Degradation 4-18
Figure 4.8 Carbon - Post Resistance Degradation 4-19
Figure 4.9 Graphite - Post Resistance Degradation 4-19
Figure 4.10 Palladium - Post Resistance Degradation 4-20
Figure 4.11 Non-Formaldehyde Electroless Copper - Post Resistance Degradation 4-20
Figure 4.12 Conductive Polymer - Post Resistance Degradation 4-21
Figure 4.13 Generic Process Steps and Typical Bath Sequences of MHC Technologies . . 4-24
Figure 4.14 Hybrid Cost Formulation Framework 4-26
Figure 4.15 Sensitivity Analysis for the Non-Conveyorized Electroless Copper Process . . 4-56
Figure 5.1 Water Consumption Rates of MHC Alternatives 5-5
Figure 7.1 Production Costs and Resource Consumption of Conveyorized Electroless
Copper Technology 7-43
Figure 7.2 Production Costs and Resource Consumption of Carbon Technology 7-46
XVI
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Figure 7.3 Production Costs and Resource Consumption of Conductive Polymer
Technology • • • 7~48
Figure 7.4 Production Costs and Resource Consumption of Graphite Technology 7-51
Figure 7.5 Production Costs and Resource Consumption of Non-Formaldehyde
Electroless Copper Technology 7-53
Figure 7.6 Production Costs and Resource Consumption of Organic-Palladium
Technology , 7"56
Figure 7.7 Production Costs and Resource Consumption of Tin-Palladium
Technology 7-59
XVll
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ACRONYMS
ABC
ADD
AsF
AT
ATSDR
BOA
BCME
Btu
BW
CAA
CC
CEB
CERCLA
CO
CO2
CTSA
CuSO4
CWA
DEC
DfE
ED
EDTA
EPA
EPCRA
FTE
g
gal
GI
gpm
H2S04
HASL
He
HEAST
HQ
HSDB
IARC
IPC
mis
ISCLT
1ST
KUB
kW
LADD
LEPC
LOAEL
activity-based costing
average daily dose
assessment factor
averaging time
Agency for Toxic Substances and Disease Registry
bill of activities
bis-chloromethyl ether
British Thermal Units
body weight
Clean Air Act
concern concentration
Chemical Engineering Branch
Comprehensive Environmental Response, Compensation and Liability Act
carbon monoxide
carbon dioxide
Cleaner Technologies Substitutes Assessment
copper sulfate
Clean Water Act
Digital Equipment Corporation of Canada
Design for the Environment
exposure duration
ethylenediaminetetraacedic acid
Environmental Protection Agency
Emergency Planning and Community Right-to-Know Act
full-time employee equivalent
gram
gallon
gastro intestinal
gallons per minute
sulfuric acid
hot air solder leveling
Henry's Law Constant
Health Effects Assessment Summary Tables
hazard quotient
Hazardous Substances Data Bank
International Agency for Research on Cancer
Institute for Interconnecting and Packaging Electronics Circuits
Integrated Risk Information System
Industrial Source Complex - Long Term
Interconnect Stress Test
Knoxville Utility Board
kilowatt
lifetime average daily dose
Local Emergency Planning Commission
lowest-observed-adverse-effect level
xvm
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MACT maximum achievable control technology
MCC Microelectronics and Computer Technology Corporation
MHC making holes conductive
MnO2 manganese dioxide
MOE margin of exposure
MSDS material safety data sheet
MIL Master Testing List
MW molecular weight
NCP National Contingency Plan
NIOSH National Institute for Occupational Safety and Health
NOAEL no-observed-adverse-effect level
NPDES National Pollutant Discharge Elimination System
NPDWR National Primary Drinking Water Regulations
NSDWR National Secondary Drinking Water Regulations
NTP National Toxicology Program
OEM original equipment manufacturer
OSHA Occupational Safety and Health Administration
PEL permissible exposure limit
PDR potential dose rate
POTW publicly-owned treatment work
PPE personal protective equipment
psi per square inch
PTH plated-through holes
PWB printed wiring board
RCRA Resource Conservation and Recovery Act
RfC reference concentration
RfD reference dose
RTECS Registry of Toxic Effects of Chemical Substances
RQ reportable quantity
SARA Superfund Amendments and Reauthorization Act
SAT Structure-Activity Team
SDWA Safe Drinking Water Act
SERC State Emergency Response Commission
SF slope factor
SIC standard industrial code
SOX sulfur oxides
SPC statistical process control
ssf surface square feet
TMCR Technology Market Research Council
TPY tons per year
TRI Toxic Release Inventory
TSCA Toxic Substances Control Act
TWA time-weighed average
UT University of Tennessee
UR utilization ratio
VOC volatile organic compounds
WOE weight-of-evidence
xix
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XX
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Executive Summary
The Printed Wiring Board Cleaner Technologies Substitutes Assessment: Making Holes
Conductive is a technical document that presents comparative risk, competitiveness, and resource
requirements information on seven technologies for performing the "making holes conductive"
(MHC) function during printed wiring board (PWB) manufacturing. MHC technologies are used
by PWB manufacturers to deposit a seed layer or coating of conductive material into the drilled
through-holes of rigid, multi-layer PWBs prior to electroplating. Volume I describes the MHC
technologies, methods used to assess the technologies, and cleaner technologies substitutes
assessment (CTSA) results. Volume II contains appendices, including detailed chemical
properties and methodology information, as well as comprehensive results of the exposure
assessment and risk characterization.
Information presented in the CTSA was developed by the U.S. Environmental Protection
Agency (EPA) Design for the Environment (DfE) Printed Wiring Board (PWB) Project and the
University of Tennessee (UT) Center for Clean Products and Clean Technologies. The
technologies evaluated are electroless copper, carbon, conductive polymer, graphite, non-
formaldehyde electroless copper, organic-palladium, and tin-palladium. Chemical and process
information is also presented for a conductive ink technology, but this technology is not
evaluated fully.1
The DfE PWB Project is a voluntary, cooperative partnership among EPA, industry,
public-interest groups, and other stakeholders to promote implementation of environmentally
beneficial and economically feasible manufacturing technologies by PWB manufacturers.
Project partners participated in the planning and execution of this CTSA by helping define the
scope and direction of the CTSA, developing project workplans, reviewing technical information
contained in this CTSA, and by donating time, materials, and their manufacturing facilities for
project research. Much of the process-specific information presented here was provided by
chemical suppliers to the PWB industry, PWB manufacturers who completed project information
requests, and PWB manufacturers who volunteered their facilities for a performance
demonstration of the baseline and alternative technologies.
The CTSA is intended to provide PWB manufacturers with information that can assist
them in making decisions that incorporate environmental concerns along with performance and
cost information when choosing an MHC technology. While the DfE PWB Project is especially
designed to assist small-and medium-sized PWB manufacturers who may have limited time or
resources to compare MHC technologies, the primary audience for the CTSA is environmental
health and safety personnel, chemical and equipment manufacturers and suppliers in the PWB
manufacturing industry, community groups concerned about community health risks, and other
technically informed decision-makers.
1 Only limited analyses were performed on the conductive ink technology for two reasons: 1) the process
is not applicable to multi-layer boards, which were the focus of the CTSA; and 2) sufficient data were not available
to characterize the risk, cost, and energy and natural resources consumption of all of the relevant process steps (e.g.,
preparation of the screen for printing, the screen printing process itself, and screen reclamation).
ES-1
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EXECUTIVE SUMMARY
I. DESIGN FOR THE ENVIRONMENT PRINTED WIRING BOARD PROJECT
The DfE PWB Project is a joint
effort of the EPA DfE Program and the UT
Center for Clean Products and Clean
Technologies in voluntary and cooperative
partnerships with the PWB industry
national trade association, the Institute for
Interconnecting and Packaging Electronic
Circuits (IPC); individual PWB
manufacturers and suppliers; the industry
research consortium, Microelectronics and
Computer Technology Corporation (MCC);
and public-interest organizations, including
Silicon Valley Toxics Coalition and
Communities for a Better Environment.
In part, the project is an outgrowth
of industry studies to identify key cleaner
technology needs in electronic systems
manufacturing. These studies include
Environmental Consciousness: A Strategic
Competitiveness Issue for the Electronics
Industry (MCC, 1993) and Electronics
Industry Environmental Roadmap (MCC,
1994). The latter study identified wet
chemistry processes, such as the traditional electroless copper process for performing the MHC
function, as potentially significant sources of hazardous waste, which require substantial
amounts of water and energy, and use chemicals that may pose environmental and health risks.
The potential for improvement in these areas led EPA's DfE Program to forge the working
partnerships that resulted in the DfE PWB Project.
Since its inception in 1994, the PWB Project has fostered open and active participation in
addressing environmental challenges faced by the PWB industry. The Project has also identified,
evaluated, and disseminated information on viable pollution prevention opportunities in the
industry. Over the long-term, the Project seeks to encourage companies to. consider
implementing cleaner technologies that will improve the environmental performance and
competitiveness of the PWB industry. Toward this goal, the CTSA presents the first complete
set of information developed by the Project on the risk, competitiveness (i.e., cost, performance,
etc.), and resource requirements of cleaner technologies.
H. OVERVIEW OF MHC TECHNOLOGIES
Until the late 1980s, virtually all PWB manufacturers employed an electroless copper
plating process to accomplish the MHC function. This process is used to plate a thin layer of
copper onto the hole walls to create the conductive surface required for electrolytic copper
EPA's Design for the Environment Program
The EPA DfE Program was formed by the Office of
Pollution Prevention and Toxics to use EPA's expertise
and leadership to facilitate information exchange and
research on risk reduction and pollution prevention
opportunities. DfE works on a voluntary basis with
mostly small- and medium-sized businesses to evaluate
the risks, performance, costs, and resource requirements
of alternative chemicals, processes, and technologies.
Additional goals of the program include:
• Changing general business practices to incorporate
environmental concerns.
• Helping individual businesses undertake
environmental design efforts through the application
of specific tools and methods.
DfE Partners include:
• Industry
• Professional institutions
• Academia
• Public-interest groups
• Other government agencies
ES-2
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EXECUTIVE SUMMARY
plating. Although the traditional electroless copper process is a mature technology that produces
reliable interconnects, the typical process line is long (17 or more tanks, depending on rinse
configurations) and may have eight or more process baths. It is also a source of formaldehyde
emissions and a major source of wastewater containing chelated, complexed copper. In recent
years, wastewater treatment requirements and new formaldehyde regulations have provided an
impetus for an intensified search for less polluting alternatives.
Process Description
MHC processes typically consist of a series of sequential chemical processing tanks
separated by water rinse stages. The process can either be operated in a vertical, non-
conveyorized immersion-type mode, or in a horizontal, conveyorized mode. In either mode,
selected baths may be operated at elevated temperature to facilitate required chemical reactions,
or agitated to improve contact between the panels and the bath chemistry. Agitation methods
employed by PWB manufacturers include panel agitation, air sparging, and fluid circulation
pumps.
Most process baths are followed by a water rinse tank to remove drag-out (i.e., the
clinging film of process solution covering the rack and boards when they are removed from a
tank). Rinsing is necessary to clean the surface of the rack and boards and avoid contaminating
subsequent process baths. Many PWB manufacturers employ a variety of rinse water reduction
methods to reduce rinse water usage and consequent wastewater generation rates. The nature and
quantity of wastewater generated from MHC process lines are discussed in Section 3.1, Source
Release Assessment, while rinse water reduction techniques are discussed in Section 6.1,
Pollution Prevention.
In the non-conveyorized mode, drilled multi-layered panels are loaded onto a rack,
desmeared, and then run through the MHC process line. Racks may be manually moved from
tank to tank, or moved by a manually controlled hoist or other means. Process tanks are usually
open to the atmosphere. To reduce volatilization of chemicals from the bath or worker exposure
to volatilized chemicals, process baths may be equipped with a local ventilation system, such as a
push-pull system, bath covers for periods of inoperation, or floating plastic balls. Conveyorized
systems are typically fully enclosed, with air emissions vented to a control technology or to the
atmosphere outside the plant.
Generic Process Steps and Bath Sequences of MHC Technologies
Figure ES. 1 presents the generic process steps and typical bath sequences evaluated in the
CTSA. The process baths depicted in the figure are an integration of the various products
submitted for evaluation by chemical suppliers within a technology category. For example, six
different electroless copper processes were submitted by chemical suppliers for evaluation in the
CTSA, and these and other suppliers offer additional electroless copper processes that may have
slightly different bath chemistries or bath sequences. In addition, the bath sequences (bath order
and rinse tank configuration) were aggregated from data collected from various PWB facilities
using the different MHC technologies. Thus, Figure ES.l lists the types and sequences of baths
in generic process lines, but the types and sequence of baths in actual lines may vary.
ES-3
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EXECUTIVE SUMMARY
ES-4
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EXECUTIVE SUMMARY
Table ES.l presents the processes evaluated in the CTSA. These are distinguished both
by process technology and equipment configuration (e.g., non-conveyorized or conveyorized).
The non-conveyorized electroless copper process is the industry standard for performing the
MHC function and is the baseline process against which alternative technologies and equipment
configurations are compared.
Table ES.l MHC Processes Evaluated in the CTSA'
MHC Technology 1
Electroless Copper (BASELINE)
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
Equipment Configuration
NoH-Coaveyorized
/
/
/
/
Conveyorized
/
/
/
/
/"
/
a The human health and aquatic toxicity hazards and chemical safely hazards of a conductive ink technology were
also evaluated, but risk was not characterized.
III. CLEANER TECHNOLOGIES SUBSTITUTES ASSESSMENT METHODOLOGY
The CTSA methodology is a means of systematically evaluating and comparing human
health and environmental risk, competitiveness (i.e., performance, cost, etc.), and resource
requirements of traditional and alternative chemicals, manufacturing methods, and technologies
that can be used to perform the same function. The publication, Cleaner Technologies
Substitutes Assessment: A Methodology & Resource Guide (Kincaid et al., 1996), presents the
basic CTSA methodology in detail. Chapters 2 through 6 in Volume I of the PWB MHC CTSA
and the appendices in Volume II describe the particular methods used in this assessment.
Key to the successful completion of any CTSA is the active participation of
manufacturers and their suppliers. This assessment was open to any MHC chemical supplier
who wanted to submit a technology, provided the technology met the following criteria:
• It is an existing or emerging technology.
There are equipment and facilities available to demonstrate its performance.
In addition, suppliers agreed to provide information about their technologies, including chemical
product formulation data, process schematics, process characteristics and constraints (e.g., cycle
time, limitations for the acid copper plating process, substrate and drilling compatibilities, aspect
ratio'capacity, range of hole sizes), bath replacement criteria, and cost information.
Issues Evaluated
The CTSA evaluated a number of issues related to the risk, competitiveness, and resource
requirements (conservation) of MHC technologies. These include the following:
ES-5
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EXECUTIVE SUMMARY
Risk: occupational health risks, public health risks, ecological hazards, and process
safety concerns.
• Competitiveness: technology performance, cost, regulatory status, and international
market status.
• Conservation: energy and natural resource use.
Occupational and public health risk information is for chronic exposure to long-term,
day-to-day releases from a PWB facility rather than short-term, acute exposures to high levels of
hazardous chemicals as could occur with a fire, spill, or periodic release. Risk information is
based on exposures estimated for a model facility, rather than exposures estimated for a specific
facility. Ecological hazards, but not risks, are evaluated for aquatic organisms that could be
exposed to MHC chemicals in wastewater discharges. Process safety concerns are summarized
from material safety data sheets (MSDSs) for the technologies and process operating conditions.
Technology performance is based on a snapshot of the performance of the MHC
technologies at volunteer test sites in the U.S. and abroad. Panels were electrically prescreened,
followed by electrical stress testing and mechanical testing, in order to distinguish variability in
the performance of the MHC interconnect. Comparative costs of the MHC technologies were
estimated with a hybrid cost model that combines traditional costs with simulation modeling and
activity-based costs. Costs are presented in terms of dollars per surface square feet (ssf) of PWB
produced.
Federal environmental regulatory information is presented for the chemicals in the MHC
technologies. This information is intended to provide an indication of the regulatory
requirements potentially associated with a technology, but not to serve as regulatory guidance.
Information on the international market status of technologies is presented as an indicator of the
effects of a technology choice on global competitiveness.
Quantitative resource consumption data are presented for the comparative rates of energy
and water use of the MHC technologies. The large amounts of water consumed and wastewater
generated by the traditional electroless copper process have been of particular concern to PWB
manufacturers, as well as to the communities in which they are located.
Data Collection
Determining the risks of the baseline and alternative MHC technologies required
information on the MHC chemical products. Chemical information provided by chemical
suppliers included the following publicly-available sources of information: MSDSs for the
chemical products in their MHC technology lines; Product Data Sheets, which are technical
specifications prepared by suppliers for PWB manufacturers that describe how to mix and
maintain the chemicals baths; and, in some cases, copies of patents. Suppliers were also asked to
provide the identities and concentrations of proprietary chemical ingredients to the project.
Electrochemicals, LeaRonal, and Solution Technology Systems provided information on
proprietary chemical ingredients to the project. Atotech provided information on one proprietary
chemical ingredient in one product line. W.R. Grace was preparing to provide information on
proprietary chemical ingredients in the conductive ink technology when it was determined that
ES-6
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EXECUTIVE SUMMARY
this information was no longer necessary because risk from the conductive ink technology could
not be characterized. The other suppliers participating in the project (Enthone-OMI,
MacDermid, and Shipley) declined to provide any proprietary information on their MHC
technologies The absence of information on proprietary chemical ingredients is a significant
source of uncertainty in the risk characterization. Risk information for proprietary ingredients, as
available, is included in this CTS A, but chemical identities, concentration, and chemical
properties are not listed.
Data Collection Forms
Appendix A in Volume II of the CTSA presents data collection forms used by the project,
including the following:
• The IPC Workplace Practices Questionnaire, which requested detailed information on
facility size, process characteristics, chemical consumption, worker activities related to
chemical exposure, water consumption, and wastewater discharges.
The Facility Background Information Sheet (developed from the IPC Workplace
Practices Questionnaire), which was sent to PWB facilities participating in the
Performance Demonstration prior to their MHC technology test date and requested
detailed information on facility and process characteristics, chemical consumption,
worker activities related to chemical exposure, water consumption, and wastewater
discharges. .
The Observer Data Sheet, which was used by an on-site observer to collect data during
the Performance Demonstration. In addition to ensuring that the performance test was
performed according to the agreed upon test protocol, the on-site observer collected
measured data, such as bath temperature and process line dimensions, and checked survey
data for accuracy. .
The Supplier Data Sheet, which included information on chemical cost, equipment cost,
water consumption rates, product constraints, and the locations of test sites for the
Performance Demonstration.
Chemical Information
Appendix B presents chemical properties and selected environmental fate properties for
the non-proprietary chemicals in MHC chemical products. Proprieties of proprietary chemical
ingredients are not included to protect proprietary chemical identities. Properties that were
measured or estimated (using a variety of standard EPA methods) included melting point,
solubility vapor pressure, octanol-water partition coefficient, boiling point, and flash point.
These properties can be used to determine the environmental fate of the MHC chemicals when
they are released to the environment.
Health
Assessments
Inherent in determining the risk associated with the MHC chemicals is a determination of
the hazard or toxicity of the chemicals. Human health hazard information for non-proprietary
chemicals is presented in Section 3± Detailed toxicity data for proprietary chemicals are not •
included to protect proprietary chemical identities. Many of the chemicals in the MHC chemical
ES-7
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EXECUTIVE SUMMARY
products have been studied to determine their health effects, and data from those studies are
available m published scientific literature. In order to collect available testing data for the MHC
chemicals, literature searches were conducted of standard chemical references and on-line
databases, including EPA's Integrated Risk Information System (IRIS), the National Library of
Medicine's Hazardous Substances Data Bank (HSDB), TOXLINE, TOXLIT, GENETOX and
the Registry of Toxic Effects of Chemical Substances (RTECS).
For many of the chemicals, EPA has identified chemical exposure levels that are known
to be hazardous if exceeded or met (e.g., no- or lowest-observed-adverse-effect level [NOAEL or
LOAEL]), or levels that are protective of human health (reference concentration [RfC] or
reference dose [RfD]). These values were taken from on-line databases and published literature
For many of the chemicals lacking toxicity data, EPA's Structure-Activity Team (SAT) estimated
human health concerns based on analogous chemicals. Hazard information is combined with
estimated exposure levels to develop an estimate of the risk associated with each chemical.
Ecological Hazard Assessments
Similar information was gathered on the ecological effects that may be expected if MHC
chemicals are released to water. Acute and chronic toxicity values were taken from on-line
database searches (TOXNET and ACQUIRE) or published literature, or were estimated using
structure-activity relationships if measured data were not available. Based on the toxicity values
MHC chemicals were assigned concern concentrations (CCs). A CC is the concentration of a
chemical in the aquatic environment which, if exceeded, may result in significant risk to aquatic
organisms. CCs were determined by dividing acute or chronic toxicity values by an assessment
factor (ranging from one to 1,000) that incorporates the uncertainty associated with toxicity data
Chemicals were also ranked according to established EPA criteria for aquatic toxicity of high
moderate, or low concern. '
Section 3.3 of the CTSA presents ecological hazard data, CCs, and aquatic toxicity
concern levels for each of the non-proprietary MHC chemicals. Table ES.2 presents the number
of MHC chemicals evaluated for each technology, the number of chemicals in each technology
with aquatic toxicity of high, moderate, or low concern, and the chemicals with the lowest CC bv
technology.
Limitations
There are a number of limitations to the project, both because of the limit of the project's
resources, the predefined scope of the project, and uncertainties inherent to risk characterization
techniques. Some of the limitations related to the risk, competitiveness, and conservation
components of the CTSA are summarized below. More detailed information on limitations and
uncertainties for a particular portion of the assessment is given in the applicable sections of this
document. A limitation common to all components of the assessment is that the MHC chemical
products assessed in this report were voluntarily submitted by participating suppliers and may not
represent the entire MHC technology market.
ES-8
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EXECUTIVE SUMMARY
Table ES.2 Aquatic Hazard Data
MHC Technology
Blectroless Copper
Carbon
Conductive Ink
Conductive Polymer
Graphite
Non-Formaldehyde
Electroless Copper
Organic-Palladium
Tin-Palladium
No, of Chemicals
Evaluated*
50b
8b
llb
6
13
10
7
26b
Ho. of Chemicals by Aquatic
Hazard Concern Level3
High
9
2
2
0
3
3
2
9
Moderate
19
2
1
1
3
3
3
6
Low
21
3 .
7
5
7
4
2
10
(Chemical with
Lowest CC
copper sulfate
(0.00002 mg/1)
copper sulfate
(0.00002 mg/1)
silver
(0.000036 mg/1)
peroxymonosulfuric acid
(0.030 mg/1)
copper sulfate
(0.00002 mg/1)
copper sulfate
(0.00002 mg/1)
sodium hypophosphite
(0.006 mg/1)
copper sulfate
(0.00002 mg/1)
a This includes chemicals from both publicly-available and proprietary data. This indicates the number of unique
chemicals; there is some overlap between public and proprietary lists for electroless copper. For technologies with
more than one chemical supplier (i.e., electroless copper, graphite, and tin-palladium), all chemicals may not be
present hi any one product line.
b No aquatic hazard data available for one chemical.
Risk
The risk characterization is a screening level assessment of multiple chemicals used in
MHC technologies. The focus of the risk characterization is on chronic (long-term) exposure to
chemicals that may cause cancer or other toxic effects, rather than on acute toxicity from brief
exposures to chemicals. The exposure assessment and risk characterization use a "model
facility" approach, with the goal of comparing the exposures and health risks of the MHC process
alternatives to the baseline non-conveyorized electroless copper technology. Characteristics of
the model facility were aggregated from questionnaire data, site visits, and other sources. This
approach does not result in an absolute estimate or measurement of risk.
In addition, the exposure and risk estimates reflect only a portion of the potential
exposures within a PWB manufacturing facility. Many of the chemicals found in MHC
technologies may also be present in other process steps of PWB manufacturing, and other risk
concerns for human health and the environment may occur from these other process steps.
Incremental reduction of exposures to chemicals of concern from an MHC process, however, will
reduce cumulative exposures from all sources in a PWB facility, provided that increased
production does not increase plant-wide pollution.
Finally, as discussed previously, Enthone-OMI, MacDermid, and Shipley submitted
publicly-available chemistry information for evaluation in the risk characterization, but declined
ES-9
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EXECUTIVE SUMMARY
to submit proprietary information. Atotech submitted publicly-available information and limited
proprietary information for one chemical in one product line. Electrochemicals, LeaRonal, and
Solution Technology Systems submitted both publicly-available and proprietary chemistry
information. The absence of complete information on proprietary chemical ingredients in
products supplied by Atotech, Enthone-OMI, MacDermid, and Shipley is a significant source of
uncertainty in the risk characterization.
Competitiveness
The Performance Demonstration was designed to provide a snapshot of the performance
of different MHC technologies. The test methods used to evaluate performance were intended to
indicate characteristics of a technology's performance, not to define parameters of performance
or to substitute for thorough on-site testing. Because the test sites were not chosen randomly, the
sample may not be representative of all PWB manufacturing facilities in the U.S. (although there
is no specific reason to believe they are not representative).
The cost analysis presents comparative costs of using an MHC technology in a model
facility to produce 350,000 ssf of PWB. As with the risk characterization, this approach results
in a comparative evaluation of cost, not an absolute evaluation or determination. The cost
analysis focuses on private costs that would be incurred by facilities implementing a technology.
It does not evaluate community benefits or costs, such as the effects on jobs from implementing a
more efficient MHC technology. However, the Social Benefits/Costs Assessment (see Section
7.2) qualitatively evaluates some of these external (i.e., external to the decision-maker at a PWB
facility) benefits and costs.
The regulatory information contained in the CTS A may be useful in evaluating the
benefits of moving away from processes containing chemicals that trigger compliance issues.
However, this document is not intended to provide compliance assistance. If the reader has
questions regarding compliance concerns, they should contact their federal, state, or local
authorities.
Conservation
The analysis of energy and water consumption is also a comparative analysis, rather than
an absolute evaluation or measurement. Similar to the cost analysis, consumption rates were
estimated based on using an MHC technology in a model facility to produce 350,000 ssf of PWB.
IV. CLEANER TECHNOLOGIES SUBSTITUTES ASSESSMENT RESULTS
Occupational Exposures and Health Risks
Health risks to workers were estimated for inhalation exposure to vapors and aerosols
from MHC baths and for dermal exposure to MHC bath chemicals. Inhalation exposure
estimates are based on the assumptions that emissions to indoor air from conveyorized lines are
negligible, that the air in the process room is completely mixed and chemical concentrations are
constant over time, and that no vapor control devices (e.g., bath covers) are used in non-
ES-10
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EXECUTIVE SUMMARY
conveyorized lines. Dermal exposure estimates are based on the assumption that workers do not
wear gloves2 and that all non-conveyorized lines are operated by manual hoist. Dermal exposure
to line operators on non-conveyorized lines could occur from routine line operation and
maintenance (e.g., bath replacement, filter replacement). Dermal exposure to line operators on
conveyorized lines was assumed to occur from bath maintenance activities alone.
The exposure assessment for this risk characterization used, whenever possible, a
combination of central tendency and high-end assumptions (i.e., 90 percent of actual values are
expected to be less) to yield an overall high-end exposure estimate. Some values used in the
exposure calculations, however, are better characterized as "what-if,"3 especially pertaining to
bath concentrations, use of gloves, and process area ventilation rates for a model facility.
Because some part of the exposure assessment for both inhalation and dermal exposures qualifies
as a "what-if descriptor, the entire assessment should be considered "what-if."
Risk results indicate that alternatives to the non-conveyorized electroless copper process
pose lower occupational risks due to reduced cancer risks and to the reduced number of
inhalation and dermal risk concerns for the alternatives. However, there are occupational
inhalation risk concerns for some chemicals in the non-formaldehyde electroless copper and tin-
palladium non-conveyorized processes. In addition, there are occupational risk concerns for
dermal contact with some chemicals in the conveyorized electroless copper process, the non-
conveyorized non-formaldehyde electroless copper process, and in the organic-palladium and tin-
palladium processes for either conveyorized or non-conveyorized equipment. Finally,
occupational health risks could not be quantified for one or more of the chemicals used in each of
the MHC technologies. This is due to the fact that proprietary chemicals in the baths were not
identified by suppliers of some chemical products and to missing toxicity or chemical property
data for some chemicals known to be present in the baths.
Table ES.3 presents chemicals of concern for potential occupational risk from inhalation.
Table ES.4 presents chemicals of concern for potential occupational risk from dermal contact.
2 Many PWB manufacturers report that their employees routinely wear gloves in the process area.
However, risk from dermal contact was estimated assuming workers do not wear gloves to account for those workers
who do not wear proper personal protective equipment.
3 A "what-if description represents an exposure estimate based on postulated questions, making
assumptions based on limited data where the distribution is unknown.
ES-11
-------
EXECUTIVE SUMMARY
Table ES.3 MHC Chemicals of Concern for Potential Occupational Inhalation Risk
Chemical3
Alkene Diol
Copper Chloride
Ethanolamine
2-Ethoxyethanol
Ethylene Glycol
Formaldehyde
Formic Acid
Methanol
Sodium Hydroxide
Sulfuric Acidc
^Nott-Coitveyorized Process1"
Electroless Copper
•
•
•
•
•
•
•
•
•
•
Non-Formaldehyde Electroless Copper
•
Tin-Palladiiwti
•
•
8 For technologies with more than one chemical supplier (e.g., electroless copper and tin-palladium), chemicals of
concern that are present hi all of the product lines evaluated are indicated in bold.
b Occupational inhalation exposure from conveyorized lines was assumed to be negligible.
0 Sulfuric acid was listed on the MSDSs for all of the electroless copper lines evaluated and four of the five tin-
palladium lines evaluated.
Table ES.4 MHC Chemicals of Concern for Potential Occupational Dermal Risk
Chemical*
Copper Chloride
Fluoroboric Acid
Formaldehyde
Nitrogen Heterocycle
Palladium11
Palladium Chloride13
Palladium Salt
Sodium Carboxylate
Sodium Chlorite
Stannous Chloride0
Tin Salt
Electroless Copper
Line
Operator
NC
•
•
•
•
•
•
•
•
C
•
•
•
•
•
•
•
•
Lab Tech
(NC or C)
•
•
•
Non-Formaldehyde
Electroless Copper
Line Operator
(NC)
•
•
Tin-Palladium
Line
Operator
NC
•
•
•
•
•
C
•
•
•
•
•
Lab Tech
(NCorC)
•
•
•
•
Organic-Palladium
Line
Operator
NC
•
C
•
Lab Tecfe
(NCorC)
•
* For technologies with more than one chemical supplier (e.g., electroless copper and tin-palladium), chemicals of
concern that are present hi all of the product lines evaluated are indicated in bold.
b Palladium or palladium chloride was listed on the MSDSs for three of the five tin-palladium lines evaluated. The
MSDSs for the two other lines did not list a source of palladium. Palladium and palladium chloride are not listed on
the MSDSs for all of the electroless copper lines evaluated.
0 Stannous chloride was listed on the MSDSs for four of the five tin-palladium lines evaluated. The MSDSs for the
remaining line did not list a source of tin. Stannous chloride is not listed on the MSDSs for all of the electroless
copper lines evaluated.
NC: Non-Conveyorized.
C: Conveyorized.
ES-12
-------
EXECUTIVE SUMMARY
Occupational cancer risks were estimated for inhalation exposure to formaldehyde and
alkyl oxide in the non-conveyorized electroless copper process, and for dermal exposure to cyclic
ether and alkyl oxide in the conveyorized graphite, conveyorized electroless copper, and non-
conveyorized electroless copper processes. Formaldehyde has been classified by EPA as Group
Bl, a Probable Human Carcinogen. Results indicate clear concern for formaldehyde inhalation
exposure; the upper bound excess individual cancer risk estimate for line operators in the non-
conveyorized electroless copper process from formaldehyde inhalation may be as high as one in
1,000, but may be 50 times less, or one in 50,000.4 Inhalation risks to other workers were
assumed to be proportional to the amount of time spent in the process area, which ranged from
three percent to 61 percent of the risk for a line operator. Occupational risks associated with
dermal and inhalatioii exposure to cyclic ether and alkyl oxide were below 1 x 10'6 (one in one
million) for the graphite and electroless copper processes and are therefore considered to be of
low concern.
Other non-proprietary chemicals in the MHC processes are suspected carcinogens.
Dimethylformamide and carbon black have been determined by the International Agency for
Research on Cancer (IARC) to possibly be carcinogenic to humans (IARC Group 2B). Like
formaldehyde, the evidence for carcinogenic effects is based on animal data. However, unlike
formaldehyde, slope factors are not available for either chemical. There are potential cancer risks
to workers from both chemicals, but they cannot be quantified. Dimethylformamide is used in
the electroless copper process. Workplace exposures have been estimated but cancer potency
and cancer risk are unknown. Carbon black is used in the carbon and conductive ink processes.
Occupational exposure due to air emissions from the carbon baths in the carbon process is
expected to be negligible because this process is typically conveyorized and enclosed. There
may be some airborne carbon black, however, from the drying oven steps. Exposures from
conductive ink were not characterized. One proprietary chemical used in the electroless copper
process, trisodium acetate amine B, was determined to possibly be carcinogenic to humans but
does not have an established slope factor.
Public Exposures and Health Risks
Public health risks were estimated for inhalation exposure only for the general population
living near a facility. Environmental releases and risk from exposure to contaminated surface
water were not quantified due to a lack of data; chemical constituents and concentrations in
wastewater resulting only from the MHC process could not be adequately characterized. Public
health risk estimates are based on the assumption that emissions from both conveyorized and
non-conveyorized process configurations are steady-state and vented to the outside. Risk was not
characterized for short-term exposures to high levels of hazardous chemicals when there is a
spill, fire, or other release.
4 To provide further information on the possible variation of formaldehyde exposure and risk, an additional
exposure estimate was provided in the Risk Characterization (Section 3.4) using average and median values (rather
than high-end) as would be done for a central tendency exposure estimate. This results in approximately a 35-fold
reduction in occupational formaldehyde exposure and risk from the estimates presented here.
ES-13
-------
EXECUTIVE SUMMARY
The risk indicators for ambient exposures to humans, although limited to airborne
releases, indicate low concern from all MHC technologies for nearby residents. The upper bound
excess individual cancer risk from formaldehyde inhalation for nearby residents from the non-
conveyorized electroless copper process was estimated to be from approaching zero to 1 x 10"7
(one in ten million), and from approaching zero to 3 x 10'7 (one in three million) for the
conveyorized electroless copper process. Formaldehyde has been classified by EPA as Group
Bl, a Probable Human Carcinogen. The risk characterization for ambient exposure to MHC
chemicals also indicates low concern from the estimated air concentrations for chronic non-
cancer effects. The upper bound excess individual cancer risk for nearby residents from alkyl
oxide in the conveyorized graphite process was estimated to be from approaching zero to
9 x 10'u (one in 11 billion); in the non-conveyorized electroless copper process from
approaching zero to 1 x 10'11 (one in 100 billion); and in the conveyorized electroless copper
process from approaching zero to 3 x 10'11 (one in 33 billion). All hazard quotients are less than
one for ambient exposure to the general population, and all MOEs for ambient exposure are
greater than 1,000 for all processes, indicating low concern from the estimated air concentrations
for chronic non-cancer effects.
Ecological Hazards
The CTSA methodology typically evaluates ecological risks in terms of risks to aquatic
organisms in streams that receive treated or untreated effluent from manufacturing processes.
Stream concentrations of MHC chemicals were not available, however, and could not be
estimated because of insufficient chemical characterization of constituents and their
concentrations in facility wastewater. This is primarily because PWB manufacturers combine
effluent from the MHC process line with effluent from other manufacturing steps prior to on-site
wastewater treatment or discharge. No information was available on the contribution of the
MHC process effluents to overall pollutant discharges. To qualitatively assess risk to aquatic
organisms, MHC chemicals were ranked based on aquatic toxicity values according to
established EPA criteria for aquatic toxicity of high, moderate, or low concern. Aquatic hazards
data are summarized hi Section III of the Executive Summary and Section 3.3 of the CTSA.
Process Safety
In order to evaluate the chemical safety hazards of the various MHC technologies,
MSDSs for chemical products used with each of the MHC technologies were reviewed. Table
ES.5 summarizes the hazardous properties listed on MSDSs for MHC chemical products.
Other potential chemical hazards can occur because of hazardous decomposition of
chemical products, or chemical product incompatibilities with other chemicals or materials.
With few exceptions, most chemical products used in MHC technologies can decompose under
specific conditions to form potentially hazardous chemicals. In addition, all of the MHC
processes have chemical products with incompatibilities that can pose a threat to worker safety if
the proper care is not taken to prevent such occurrences.
ES-14
-------
EXECUTIVE SUMMARY
MfiC Technology
Electroless Copper
Carbon
Conductive Ink
Conductive Polymerb
Graphite
Non-Formaldehyde
Electroless Copper
Organic-Palladium13
Tin-Palladium
Types of Hazardous Properties Reported on MSDS&"
flammable, combustible, explosive, fire hazard, corrosive, oxidizer, reactive,
unstable, acute health hazard, chronic health hazard, eye damage
flammable, corrosive, oxidizer, reactive, acute health hazard, chronic health
hazard, eye damage
explosive, eye damage
flammable, corrosive, eye damage
fire hazard, corrosive, oxidizer, unstable, acute health hazard, chronic health
hazard, eye damage
flammable, corrosive, oxidizer, reactive, acute health hazard, chronic health
hazard, eye damage
unstable, eye damage
flammable, combustible, explosive, fire hazard, corrosive, reactive, sensitizer,
acute health hazard, chronic health hazard, eye damage
hazardous properties may not be listed for any one product line.
b Based on German equivalent of MSDS, which may not have as stringent reporting requirements as U.S. MSDS.
Work-related injuries from equipment, improper use of equipment, bypassing equipment
safety features, failure to use personal protective equipment, and physical stresses that may
appear gradually as a result of repetitive motion are all potential process safety hazards to
workers. Reducing the potential for work-related injuries is critical in an effective and ongoing
safety training program. Without appropriate training, the number of work-related accidents and
injuries is likely to increase, regardless of the technology used.
Performance
The performance of the MHC technologies was tested using production run tests. In
order to complete this evaluation, PWB panels, designed to meet industry "middle-of-the-road"
technology, were manufactured at one facility, run through individual MHC lines at 26 facilities,
then electroplated at one facility. The panels were electrically prescreened, followed by electrical
stress testing and mechanical testing, in order to distinguish variability in the performance of the
MHC interconnect. The Performance Demonstration was conducted with extensive input and
participation from PWB manufacturers, their suppliers, and PWB testing laboratories. The test
vehicle was a 24" x 18" x 0.062" 8-layer panel. (See Section 4.1 for a detailed description of the
test vehicle.) Each test site received three panels for processing through the MHC line.
Test sites were submitted by suppliers of the technologies, and included production
facilities, testing facilities (beta sites), and supplier testing facilities. Because the test sites were
not chosen randomly, the sample may not be representative of all PWB manufacturing facilities
(although there is no specific reason to believe that they are not representative). In addition, the
number of test sites for each technology ranged from one to ten. Due to the smaller number of
test sites for some technologies, results for these technologies could more easily be due to chance
than the results from technologies with more test sites. Statistical relevance could not be
determined.
ES-15
-------
EXECUTIVE SUMMARY
Product performance for this study was divided into two functions: plated through-hole
(PTH) cycles to failure and the integrity of the bond between the internal lands (post) and PTH
(referred to as "post separation5'). The PTH cycles to failure observed in this study is a function
of both electrolytic plating and MHC process. The results indicate that each MHC technology
has the capability to achieve comparable (or superior) levels of performance to electroless
copper. Post separation results indicated percentages of post separation that were unexpected by
many members of the industry. It was apparent that all MHC technologies, including electroless
copper, are susceptible to this type of failure.
Cost
Comparative costs were estimated using a hybrid cost model which combined traditional
costs with simulation modeling and activity-based costs. The cost model was designed to
determine the total cost of processing a specific amount of PWBs through a fully operational
MHC line, in this case, 350,000 ssf. The cost model did not estimate start-up costs for a facility
switching to an alternative MHC technology or the costs of other process changes that may be
required to implement an alternative technology. Total costs were divided by the throughput
(350,000 ssf) to determine a unit cost in dollars per ssf.
The cost components considered include capital costs (primary equipment, installation,
and facility costs), materials costs (limited to chemical costs), utility costs (water, electricity, and
natural gas costs), wastewater costs (limited to wastewater discharge cost), production costs'
(production labor and chemical transport costs), and maintenance costs (tank clean up, bath
setup, sampling and analysis, and filter replacement costs). Other cost components may
contribute significantly to overall costs, but could not be quantified. These include wastewater
treatment cost, sludge recycling and disposal cost, other solid waste disposal costs, and quality
costs.
Table ES.6 presents results of the cost analysis, which indicate all of the alternatives are
more economical than the non-conveyorized electroless copper process. In general,
conveyorized processes cost less than non-conveyorized processes. Chemical cost was the single
largest component cost for nine of the ten processes. Equipment cost was the largest cost for the
non-conveyorized electroless copper process. Three separate sensitivity analyses of the results
indicated that chemical costs, production labor costs, and equipment costs have the greatest effect
on the overall cost results.
ES-16
-------
EXECUTIVE SUMMARY
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ES-17
-------
EXECUTIVE SUMMARY
Regulatory Status
Discharges of MHC chemicals may be restricted by federal, state or local air, water or
solid waste regulations, and releases may be reportable under the federal Toxic Release Inventory
program. Federal environmental regulations were reviewed to determine the federal regulatory
status of MHC chemicals.5 Table ES.7 lists the number of chemicals used in an MHC
technology that are subject to federal environmental regulations. Different chemical suppliers of
a technology do not always use the same chemicals in their particular product lines. Thus, all of
these chemicals may not be present in any one product line.
International Information
Several suppliers indicated that market shares of the MHC alternatives are increasing
internationally quicker than they are increasing in the U.S. The cost-effectiveness of an
alternative has been the main driver causing PWB manufacturers abroad to switch from an
electroless copper process to one of the newer alternatives. In addition to the increased capacity
and decreased labor requirements of some of the MHC alternatives over the electroless copper
process, environmental concerns also affected the process choice. For instance, the rate at which
an alternative consumes water and the presence or absence of strictly regulated chemicals are two
factors which have a substantial effect on the cost-effectiveness of MHC alternatives abroad.
Resource Conservation Summary
Resources typically consumed by the operation of an MHC process include water used for
rinsing panels, process chemicals used on the process line, energy used to heat process baths and
power equipment, and wastewater treatment chemicals. The energy and water consumption rates
of the MHC process alternatives were calculated to determine if implementing an alternative to
the baseline process would reduce consumption of these resources during the manufacturing
process. Process chemical and treatment chemical consumption rates could not be quantified due
to the variability of factors that affect the consumption of these resources. Table ES.8 presents
the energy and water consumption rates of MHC technologies.
The rate of water consumption is directly related to the rate of wastewater generation.
Most PWB facilities discharge process rinse water to an on-site wastewater treatment facility for
pretreatment prior to discharge to a publicly-owned treatment works (POTW). A pollution
prevention analysis identified a number of pollution prevention techniques that can be used to
reduce rinse water consumption. These include use of more efficient rinse configurations, use of
flow control technologies, and use of electronic sensors to monitor contaminant concentrations in
rinse water. Further discussion of these and other pollution prevention techniques can be found
in the Pollution Prevention section of the CTSA (Section 6.1) and in PWB Project pollution
prevention case studies, which are available from the Pollution Prevention Information
Clearinghouse (see p. ii).
In some cases, state or local requirements may be more restrictive than federal requirements. However,
due to resource limitations, only federal regulations were reviewed.
ES-18
-------
EXECUTIVE SUMMARY
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ES-19
-------
EXECUTIVE SUMMARY
Table ES.8 Energy and Water Consumption Rates of MHC Technologies
Process Type
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Water Consumption
(gal/ssf)
11.7
1.15
1.29
0.73
0.45
3.74
1.35
1.13
1.80
0.57
Energy Consumption
(Btu/ssf)
573
138
514
94.7
213
270
66.9
148
131
96.4
Social Benefits/Costs Assessment
The social benefits and costs of the MHC technologies were qualitatively assessed to
compare the benefits and costs of switching from the baseline technology to an alternative, while
considering both the private and external costs and benefits. Private costs typically include any
direct costs incurred by the decision-maker and are generally reflected in the manufacturer's
balance sheet. In contrast, external costs are incurred by parties other than the primary
participants to the transaction. Economists distinguish between private and external costs
because each will affect the decision-maker differently. Although external costs are real costs to
some members of society, they are not incurred by the decision-maker and firms do not normally
take them into account when making decisions.
Table ES.9 compares some of the relative benefits and costs of each technology to the
baseline, including production costs, worker health risks, public health risks, aquatic toxicity
concerns, water consumption, and energy consumption. The effects on jobs of wide-scale
adoption of an alternative is not included in the table because the potential for job losses was not
evaluated in the CTSA. However, the results of the CTSA cost analysis suggest there are
significantly reduced labor requirements for the alternatives. Clearly, if manufacturing jobs were
lost, it would be a significant external cost to the community and should be considered by PWB
manufacturers when choosing among MHC technologies.
While each alternative presents a mixture of private and external benefits arid costs, it
appears that each of the alternatives have social benefits as compared to the baseline. In addition,
at least three of the alternatives appear to have social benefits over the baseline in every category.
These are the conveyorized conductive polymer process and both conveyorized and non-
conveyorized organic-palladium processes. Note, however, that the supplier of these
technologies declined to provide complete information on proprietary chemical ingredients,
meaning health risks could not be fully assessed.
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EXECUTIVE SUMMARY
ES-21
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EXECUTIVE SUMMARY
V. CONCLUSIONS
The CIS A evaluated the risk, competitiveness, and resource requirements of seven
technologies for performing the MHC function during PWB manufacturing. These technologies
are electroless copper, carbon, conductive polymer, graphite, non-formaldehyde electroless
copper, organic-palladium, and tin palladium. Chemical and process information are also
presented for a conductive ink technology.
The results of the CTSA suggest that the alternatives to traditional non-conveyorized
electroless copper processes (the baseline process) not only have environmental and economic
benefits, but also perform the MHC function as well as the baseline. While there appears to be
enough information to show that a switch away from traditional electroless copper processes has
reduced risk benefits, there is not enough information to compare the alternatives to this process
among themselves for all their environmental and health consequences. This is because not all
proprietary chemicals have been identified, and because toxicity values are not available for
some chemicals. In addition, it is important to note that there are additional factors beyond those
assessed in this CTSA which individual businesses may consider when choosing among
alternatives. The actual decision of whether or not to implement an alternative is made outside
of the CTSA process.
To assist PWB manufacturers who are considering switching to an MHC alternative, the
DfE PWB Project has prepared an implementation guide that describes lessons learned by other
PWB manufacturers who have switched from non-conveyorized electroless copper to one of the
alternative processes.6 In addition, the University of Tennessee Department of Industrial
Engineering can provide technical support to facilities that would like to use the cost model
developed for the CTSA to estimate their own manufacturing costs should they switch to an
MHC alternative.
Implementing Cleaner Technologies in the Printed Wiring Board Industry: Making Holes Conductive
(EPA 744-R-97-001, February 1997). This and other DfE PWB Project documents can be obtained by contacting
EPA's Pollution Prevention Information Clearinghouse at (202) 260-1023.
ES-22
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Chapter 1
Introduction
This document presents the results of a cleaner technologies substitutes assessment
(CTS A) of seven technologies for performing the "making holes conductive" (MHC) function
during the manufacture of printed wiring boards (PWBs). MHC technologies are used by PWB
manufacturers to deposit a seed layer or coating of conductive material into the drilled through-
holes of rigid, multi-layer PWBs prior to electroplating. The technologies evaluated here are
electroless copper, carbon, conductive polymer, graphite, non-formaldehyde electroless copper,
organic-palladium, and tin-palladium. Chemical and process information is also presented for a
conductive ink technology, but this technology is not evaluated fully.1
For the purposes of this evaluation, the non-conveyorized electroless copper process is
considered the baseline process against which alternative technologies and equipment
configurations (e.g., non-conveyorized or conveydrized) are compared. This CTSA is the
culmination of over two years of research by the U.S. Environmental Protection Agency (EPA)
Design for the Environment (DfE) PWB Project and the University of Tennessee (UT) Center for
Clean Products and Clean Technologies on the comparative risk, performance, cost, and natural
resource requirements of the alternatives as compared to the baseline.
The DfE PWB Project is a voluntary, cooperative partnership among EPA, industry,
public-interest groups, and other stakeholders to promote implementation of environmentally
beneficial and economically feasible manufacturing technologies by PWB manufacturers.
Project partners participated in the planning and execution of this CTSA by helping define the
scope and direction of the CTSA, developing project workplans, donating time, materials, and
their manufacturing facilities for project research, and reviewing technical information contained
in this CTSA. Much of the process-specific information presented here was provided by
.chemical suppliers to the PWB industry, PWB manufacturers who responded to project
information requests, and PWB manufacturers who volunteered their facilities for a performance
demonstration of the baseline and alternative technologies.
Section 1.1 presents project background information, including summary descriptions of
the EPA DfE Program and the DfE PWB Project. Section 1.2 is 'an overview of the PWB
industry, including the types of PWBs produced, the market for PWBs, and the overall PWB
manufacturing process. Section 1.3 summarizes the CTSA methodology, including a discussion
of how technologies were selected for evaluation in the CTSA, the boundaries of the evaluation,
issues evaluated, data sources, and project limitations. Section 1.4 describes the organization of
the remainder of the CTSA document.
1 Only limited analyses were performed on the conductive ink technology for two reasons: 1) the process
is not applicable to multi-layer boards, which were the focus of the CTSA; and 2) sufficient data were not available
to characterize the risk, cost, and energy and natural resources consumption of all of the relevant process steps (e.g.,
preparation of the screen for printing, the screen printing process itself, and screen reclamation).
1-1
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1.1 PROJECT BACKGROUND
1.1 PROJECT BACKGROUND
The PWB is the underlying link between semiconductors, computer chips, and other
electronic components. Therefore, PWBs are an irreplaceable part of many "high-tech" products
in the electronics, defense, communications, and automotive industries. PWB manufacturing,
however, typically generates a significant amount of hazardous waste, requires a substantial '
amount of water and energy, and uses chemicals that may pose potential environmental and
health risks.
To address these issues, the PWB industry has been actively seeking to identify and
evaluate cleaner technologies and pollution prevention opportunities. However, many PWB
manufacturers are small businesses that cannot afford to independently develop the data needed
to evaluate new technologies and redesign their processes. The DfE PWB Project was initiated
to develop that data, by forming partnerships between the EPA DfE Program, the PWB industry,
and other interested parties to facilitate the evaluation and implementation of alternative
technologies that reduce health and environmental risks and production costs. The EPA DfE
Program and the DfE PWB Project are discussed in more detail below.
1.1.1 EPA DfE Program
EPA's Office of Pollution Prevention and Toxics created the DfE Program in 1991. The
Program uses EPA's expertise and leadership to facilitate information exchange and research on
risk reduction and pollution prevention opportunities. DfE works on a voluntary basis with
small- and mostly medium-sized businesses to evaluate the risks, performance, costs, and
resource requirements of alternative chemicals, processes, and technologies. Additional goals of
the program include:
• Changing general business practices to incorporate environmental concerns.
• Helping individual businesses undertake environmental design efforts through the
application of specific tools and methods.
The DfE Program catalyzes voluntary environmental improvement through stakeholder
partnerships. DfE partners include industry, trade associations, research institutions,
environmental and public-interest groups, academia, and other government agencies! By
involving representatives from each of these stakeholder groups, DfE projects gain the necessary
expertise to perform the project's technical work and improve the quality, credibility, and utility
of the project's results.
1.1.2 DfE Printed Wiring Board Project
The DfE PWB Project is a voluntary, cooperative partnership among EPA, industry,
public-interest groups, and other stakeholders to promote implementation of environmentally
beneficial and economically feasible manufacturing technologies by PWB manufacturers. In
part, the project is an outgrowth of industry efforts to identify key cleaner technology needs in
electronic systems manufacturing. The results of these industry studies are presented in two
reports prepared by Microelectronics and Computer Technology Corporation (MCC), an industry
research consortium: Environmental Consciousness: A Strategic Competitiveness Issue for the
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1.1 PROJECT BACKGROUND
Electronics Industry (MCC, 1993) and Electronics Industry Environmental Roadmap (MCC,
1994).
The first study identified wet chemistry processes, such as those used in PWB fabrication,
as water- and energy-intensive processes that generate significant amounts of hazardous waste.
The study concluded that effective collaboration among government, industry, academia, and the
public is imperative to proactively address the needs of environmental technologies, policies, and
practices (MCC, 1993). As follow-up, the industry embarked on a collaborative effort to develop
an environmental roadmap for the electronics industry. The roadmap project involved more than
100 organizations, including EPA, the Department of Energy, the Advanced Research Projects
Agency, and several trade associations. The PWB industry national trade association, the
Institute for Interconnecting and Packaging Electronic Circuits (IPC), was instrumental in
developing the information on PWBs through its Environmental, Health, and Safety Committee.
The highest priority need identified for PWB manufacturers was for more efficient use,
regeneration, and recycling of hazardous wet chemistries. One proposed approach to meet this
need was to eliminate formaldehyde from materials and chemical formulations by researching
alternative chemical formulations. Another priority need for the industry was to reduce water
consumption and discharge, which can also be accomplished with alternative wet chemistries
that have reduced numbers of rinse steps. Electroless copper technologies for MHC use
formaldehyde as a reducing agent and consume large amounts of water.
The potential for improvement in these areas led EPA's DfE Program to forge working
partnerships with IPC, individual PWB manufacturers and suppliers, research institutions such as
MCC and UT's Center for Clean Products and Clean Technologies, and public-interest
organizations, including the Silicon Valley Toxics Coalition and Communities for a Better
Environment. These partnerships resulted in the DfE PWB Project.
Since its inception in 1994, the primary focus of the Project has been the evaluation of
environmentally preferable MHC technologies. This CTSA is the culmination of this effort. The
project has also:
• Identified, evaluated, and disseminated information on viable pollution prevention
opportunities for the PWB industry through a review of pollution prevention and control
practices in the industry (EPA, 1995a).
• Prepared several case studies of pollution prevention opportunities (EPA, 1995b; EPA,
1995c; EPA, 1996a; EPA, 1996b; EPA, 1996c).
• Prepared a summary of federal environmental regulations affecting the electronics
industry (EPA, 1995d).
• Developed a summary document that profiles the PWB industry and defines and
describes the typical manufacturing steps in the manufacture of rigid, multi-layer PWBs
(EPA, 1995e).
• Prepared an implementation guide for PWB manufacturers interested in switching from
electroless copper to an alternative MHC technology (EPA, 1997).
Future activities will include an evaluation of alternative surface finishes that can substitute for
the hot-air solder leveling process.
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1.2 OVERVIEW OF PWB ES1DUSTRY
1.2 OVERVIEW OF PWB INDUSTRY
1.2.1 Types of Printed Wiring Boards
PWBs may be categorized in several ways, including by layer counts or by substrate.
Layer counts are the number of circuit layers present on a single PWB, giving an indication of the
overall complexity of the PWB. The most common categories of layer counts are multi-layer,
double-sided, and single-sided PWBs. Multi-layer PWBs contain more than two layers of
circuitry, with at least one layer imbedded in the substrate beneath the surface of the board.
Multi-layer boards may consist of 20 or more interconnected layers, but four, six, and eight layer
boards are more common. Double-sided boards have circuitry on both sides of a board, resulting
in two interconnected layers, while single-sided PWBs have only one layer of circuitry. Double-
sided and single-sided PWBs are generally easier to produce than multi-layer boards (EPA,
1995e).
PWB substrates, or base material types, fall into three basic categories: rigid PWBs,
flexible circuits, and rigid-flex combinations. Rigid multi-layer PWBs dominate the domestic
production value of all PWBs (see Section 1.2.2, below) and are the focus of this CTSA.
Rigid PWBs typically are constructed of glass-reinforced epoxy-resin systems that
produce a board less than 0.1" thick. The most common rigid PWB thickness is 0.062", but there
is a trend toward thinner PWBs. Flexible circuits (also called flex circuits) are manufactured on
polyamide and polyester substrates that remain flexible at finished thicknesses. Ribbon cables
are common flexible circuits. Rigid-flex PWBs are essentially combinations or assemblies of
rigid and flexible PWBs. They may consist of one or more rigid PWBs that have one or more
flexible circuits laminated to them during the manufacturing process. Three-dimensional circuit
assemblies can be created with rigid-flex combinations (EPA, 1995e).
1.2.2 Industry Profile
The total world market for PWBs is about $21 billion, with U.S. production accounting
for about one quarter (more than $5 billion). The U.S.-dominated world market for PWBs
eroded from 1980 to 1990, but has come back slightly in recent years. The PWB industry is
characterized by highly competitive global sourcing with low profit margins (EPA, 1995e).
The U.S. has approximately 700 to 750 independent PWB manufacturing plants and
about 70 captive facilities (e.g., original equipment manufacturers [OEMs] that make PWBs for
use internally in their own electronic products) (EPA, 1995e). California, Minnesota, Texas,
Illinois, Massachusetts, and Arizona have the highest number of PWB manufacturing plants, but
there are PWB manufacturing facilities in virtually all 50 states and territories. More than 75
percent of U.S.-made PWBs are produced by independent shops (EPA, 1995e).
Around 90 percent of independent PWB manufacturers are small- to medium-sized
businesses with annual sales under $10 million, but these shops only account for 20 to 25 percent
of total U.S. sales (EPA, 1995e). Conversely, about seven percent of PWB manufacturers are
larger independent shops with annual sales over $20 million, but these shops account for about
55 to 62 percent of total U.S. sales (EPA, 1995e).
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1,2 OVERVIEW OF PWB INDUSTRY
Currently, rigid multi-layer boards dominate the domestic production value of PWBs,
accounting for approximately 66 percent of the domestic market (EPA, 1995e). Double-sided
boards account for about one quarter of the domestic market, with single-sided and flexible
circuits making up the remainder. The market for multi-layer boards was about $3.4 billion in
1993, up from approximately $700 million in 1980 (EPA, 1995e).
The PWB industry directly employs about 75,000 people, with about 68 percent of
employment in production jobs. This is the highest ratio of production jobs for U.S. electronics
manufacturing (EPA, 1995e). Additional jobs related to the industry are generated by PWB
material and equipment suppliers and the OEMs that produce PWBs for internal use. Further
information about the industry may be found in Printed Wiring Board Industry and Use Cluster
Profile (EPA, 1995e).
1.2.3 Overview of Rigid Multi-Layer PWB Manufacturing
Multi-layer boards consist of alternating layers of conductor and insulating material
bonded together. Holes are drilled through the boards to provide layer-to-layer connection on
multi-layered circuits. Since most rigid PWB substrates consist of materials that will not conduct
electricity (e.g., epoxy-resin and glass), a seed layer or coating of conductive material must be
deposited into the hole barrels before electrolytic copper plating can occur. The MHC
technologies evaluated in this report are processes to deposit this seed layer or coating of
conductive material into drilled through-holes prior to electroplating. Traditionally, this has been
done using an electroless copper technology to plate copper onto the hole barrels.
PWBs are most commonly manufactured by etching copper from a solid foil to form the
desired interconnect pattern (subtractive processing). Another processing method, called
additive processing, is used to selectively plate or metallize a board by building the circuits on
catalyzed laminate with no metal foil on the surface. Additive processes to make multi-layer
boards have only recently been under development in this country, and none are in widespread
use (EPA, 1995e). Figure 1.1 illustrates the basic steps to fabricate rigid, multi-layer PWBs by
subtractive processing.
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1.2 OVERVIEW OF PWB INDUSTRY
filfl'
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1.3 CTSA METHODOLOGY
1.3 CTSA METHODOLOGY
The CTSA methodology is a means of systematically evaluating and comparing human
health and environmental risk, competitiveness (i.e., performance, cost, etc.), and resource
requirements of traditional and alternative chemicals, manufacturing methods, and technologies
in a particular use cluster. A use cluster is a set of chemical products, technologies, or processes
that can substitute for one another to perform a particular function. A CTSA document is the
repository for the technical information developed by a DfE project on a use cluster. Thus, MHC
technologies comprise the use cluster that is the focus of this CTSA.
The overall CTSA methodology used in this assessment was developed by the EPA DfE
Program, the UT Center for Clean Products and Clean Technologies, and other partners in
voluntary, industry-specific pilot projects. The publication, Cleaner Technologies Substitutes
Assessment: A Methodology & Resource Guide (Kincaid, et al., 1996) presents the CTSA
methodology in detail. This section summarizes how the various technologies were selected for
evaluation in the CTSA, identifies issues evaluated and data sources, and describes the project
limitations. Chapters 2 through 6, and appendices, describe in detail the methods used to
evaluate the technologies.
1.3.1 Identification of Alternatives and Selection of Project Baseline
Once the use cluster for the CTSA was chosen, industry representatives identified
technologies that may be used to accomplish the MHC function. Initially, nine technology
categories were identified, including seven wet chemistry processes, one screen printing process,
and one mechanical process. These include:
• Wet chemistry: electroless copper, carbon, conductive polymer, electroless nickel,
graphite, non-formaldehyde electroless copper, and palladium.
• Screen printing: conductive ink.
• Mechanical: lomerson.
Suppliers were contacted by EPA and asked to submit their product lines in these
technology categories for evaluation in the CTSA. Criteria for including a technology in the
CTSA were the following:
• It is an existing or emerging technology.
• There are equipment and facilities available to demonstrate its performance.
In addition, suppliers agreed to provide information about their technologies, including chemical
product formulation data, process schematics, process characteristics and constraints (e.g., cycle
time, limitations for the acid copper plating process, substrate and drilling compatibilities, aspect
ratio capacity, range of hole sizes), bath replacement criteria, and cost information.
Product lines and publicly-available chemistry (e.g., product formulation) data were
submitted for all of the technologies except electroless nickel and the lomerson process. Industry
participants indicated the lomerson process is an experimental technology that has not been
successfully implemented, Thus, seven categories of technologies were carried forward for
1-7
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1.3 CTSA METHODOLOGY
further evaluation in the CTSA. After review of publicly-available chemistry data submitted by
the suppliers, the palladium technology category was further divided into two technology
categories—organic-palladium and tin-palladium—bringing the total number of technology
categories slated for evaluation to eight. For the purposes of a Performance Demonstration
conducted as part of this CTSA, however, the organic-palladium and tin-palladium technologies
were grouped together into a single palladium technology category.
Further review of the technologies indicated that the conductive ink technology is not
applicable to multi-layer boards and sufficient data were not available to characterize the risk,
cost, energy, and natural resources consumption of all of the relevant process steps (i.e.,
preparation of screen for printing, the screen printing process itself, and screen reclamation).
Thus, only a process description, chemical hazard data (i.e., safety hazards, human health
hazards, and aquatic toxicity), and regulatory information are presented for the conductive ink
technology.
The electroless copper technology was selected as the project baseline for the following
reasons:
• It is generally regarded to be the industry standard and holds the vast majority of the
market for MHC technologies.
• Possible risk concerns associated with formaldehyde exposure, the large amount of water
consumed and wastewater generated by electroless copper processes, and the presence of
chelators that complicate wastewater treatment have prompted many PWB manufacturers
to independently seek alternatives to electroless copper.
As with other MHC technologies, electroless copper processes can be operated using vertical,
immersion-type, non-conveyorized equipment or horizontal, conveyorized equipment.
Conveyorized MHC equipment is a relatively new innovation in the industry and is usually more
efficient than non-conveyorized equipment. However, most facilities in the U.S. still use a non-
conveyorized electroless copper process to perform the MHC function. Therefore, the baseline
technology was further defined to only include non-conveyorized electroless copper processes.
Conveyorized electroless copper processes, and both non-conveyorized and conveyorized
equipment configurations of the other technology categories are all considered to be alternatives
to non-conveyorized electroless copper.
1.3.2 Boundaries of the Evaluation
For the purposes of the environmental evaluation (e.g., health and environmental hazards,
exposure, risk, and resource consumption), the boundaries of this evaluation can be defined in
terms of the overall life cycle of the MHC products and in terms of the PWB manufacturing
process. The life cycle of a product or process encompasses extraction and processing of raw
materials, manufacturing, transportation and distribution, use/re-use/maintenance, recycling, and
final disposal. As discussed in Section 1.2.3, rigid, multi-layer PWB manufacturing
encompasses a number of process steps, of which the MHC process is one.
The life-cycle stages evaluated in this study are primarily the use of MHC chemicals at
PWB facilities and the release or disposal of MHC chemicals from PWB facilities. However, in
1-8
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1.3 CTSA METHODOLOGY
addition to evaluating the energy consumed during MHC line operation, the analysis of energy
impacts (Section 5.2) also discusses the pollutants generated from producing the energy to
operate the MHC line as well as energy consumed in other life-cycle stages, such as the
manufacture of chemical ingredients. In addition, while information is presented on the types
and quantities of wastewater and solid waste generated by MHC process lines, there was
insufficient information to characterize the risk from these environmental releases. This is
discussed in more detail in Section 3.1, Source Release Assessment.
In terms of the PWB manufacturing process, this analysis focused entirely on the MHC
process, defined as beginning with a panel that has been desmeared2 and freed of all residual
desmear chemistry and ending when a layer of conducting material has been deposited that is
stable enough to proceed to either panel or pattern plating. The MHC process was defined
slightly differently however, for the Performance Demonstration: beginning with the desmear
step, proceeding through the MHC process, and ending with 0.1 mil of copper flash plating. The
slightly different definition was needed to address compatibility issues associated with the
desmear step and to protect the test boards during shipment to a single facility for electroplating
(see Section 4.1, Performance Demonstration Results).
The narrow focus on MHC technologies yields some benefits to the evaluation, but it also
has some drawbacks. Benefits include the ability to collect extremely detailed information on the
relative risk, performance, cost, and resources, requirements of the baseline technology and
alternatives. This information provides a more complete assessment of the technologies than has
previously been available and would not be possible if every step in the PWB manufacturing
process was evaluated. Drawbacks include the inability to identify all of the plant-wide benefits,
costs, or pollution prevention opportunities that could occur when implementing an alternative to
the baseline electroless copper technology. However, given the variability in workplace practices
and operating procedures at PWB facilities, these other benefits and opportunities are expected to
vary substantially among facilities and would be "difficult to assess in a comparative evaluation
such as a CTSA. Individual PWB manufacturers are urged to assess their overall operations for
pollution prevention opportunities when implementing an alternative technology.
1.3.3 Issues Evaluated
The CTSA evaluated a number of issues related to the risk, competitiveness, and resource
requirements (conservation) of MHC technologies. These include the following:
• Risk: occupational health risks, public health risks, ecological hazards, and process
safety concerns.
• Competitiveness: technology performance, cost, regulatory status, and international
market status.
• Conservation: energy and natural resource use.
2 Besmearing is the process step to remove a small amount of epoxy-resin from the hole barrels, including
any that may have been smeared across the copper interface during drilling.
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1.3 CTSA METHODOLOGY
Occupational and public health risk information is for chronic exposure to long-term,
day-to-day releases from a PWB facility rather than short-term, acute exposures to high levels of
hazardous chemicals as could occur with a fire, spill, or other periodic release. Risk information
is based on exposures estimated for a model facility, rather than exposures estimated for a
specific facility. Ecological hazards, but not risks, are evaluated for aquatic organisms that could
be exposed to MHC chemicals in wastewater discharges. Process safety concerns are
summarized from material safety data sheets (MSDSs) for the technologies and process operating
conditions.
Technology performance is based on a snapshot of the performance of the MHC
technologies at volunteer test sites in the U.S. and abroad. Panels were electrically prescreened,
followed by electrical stress testing and mechanical testing, in order to distinguish variability in '
the performance of the MHC interconnect. Comparative costs of the MHC technologies were
estimated with a hybrid cost model that combines traditional costs with simulation modeling and
activity-based costs. Costs are presented in terms of dollars per surface square feet (ssf) of PWB
produced.
Federal environmental regulatory information is presented for the chemicals in the MHC
technologies. This information is intended to provide an indication of the regulatory
requirements associated with a technology, but not to serve as regulatory guidance. Information
on the international market status of technologies is presented as an indicator of the effects of a
technology choice on global competitiveness.
Quantitative resource consumption data are presented for the comparative rates of energy
and water use of the MHC technologies. The large amounts of water consumed and wastewater
generated by the traditional electroless copper process have been of particular concern to PWB
manufacturers, as well as to the communities in which they are located.
1.3.4 Primary Data Sources
Much of the process-specific information presented in this CTSA was provided by
chemical suppliers to the PWB industry, PWB manufacturers who responded to project
information requests, and PWB manufacturers who volunteered their facilities for a performance
demonstration of the baseline and alternative technologies. The types of information provided by
chemical suppliers and PWB manufacturers are summarized below.
Chemical Suppliers
The project was open to any chemical supplier who wanted to participate, provided their
technologies met the criteria described in Section 1.3.1. Table 1.1 lists the suppliers who
participated in the CTSA and the categories of MHC technologies they submitted for evaluation.
It should be noted that this is not a comprehensive list of MHC technology suppliers. EPA made
every effort to publicize the project through trade associations, PWB manufacturers, industry
conferences and other means, but some suppliers did not learn of the project until it was too late
to submit technologies for evaluation.
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1.3 CTSA METHODOLOGY
Table 1 ,1 MHC Technologies Submitted by Chemical Suppliers
Chemical {Supplier
AtotechU.S.A.,Inc.
Electrochemicals, Lac.
Enthone-OML, Inc.
LeaRonal, Inc.
MacDermid, Inc.
Shipley Company
Solution Technology
Systems
MHC Technology
Sftectroless
Copper
/
/
/
/
/
Carbon
/
Conductive
Ink
/
Conductive
Polymer
/
Graphite
/
/
Non-<
Formaldehyde
Electrotess
Copper
/
Organic-
Palladium
Ifo*
Palladium
/
Each of the chemical suppliers provided the following: MSDSs for the chemical products
in their MHC technology lines; Product Data Sheets, which are technical specifications prepared
by suppliers for PWB manufacturers that describe how to mix and maintain the chemicals baths;
and, in some cases, copies of patents.3 Suppliers were also asked to complete a Supplier Data
Sheet designed for the project, which included information on chemical cost, equipment cost,
water consumption rates, product constraints, and the locations of test sites for the Performance
Demonstration. Appendix A contains a copy of the Supplier Data Sheet.
PWB Manufacturers
PWB manufacturers were asked to participate in a study of workplace practices. The IPC
Workplace Practices Questionnaire requested detailed information on facility size, process
characteristics, chemical consumption, worker activities related to chemical exposure, water
consumption, and wastewater discharges. The questionnaire was distributed to PWB
manufacturers by IPC. PWB manufacturers returned the completed questionnaires to IPC, which
removed all facility identification and assigned a code to the questionnaires prior to forwarding
them to the UT Center for Clean Products. In this manner, PWB manufacturers were guaranteed
confidentially of data. However, when Center staff had follow-up questions on a questionnaire
response, many facilities allowed the Center to contact them directly, rather than go through IPC
to discuss the data.
For the Performance Demonstration project the IPC Workplace Practices Questionnaire
was modified and divided into two parts: a Facility Background Information Sheet and an
Observer Data Sheet. The Facility Background Information Sheet was sent to PWB facilities
participating in the Performance Demonstration prior to their MHC technology test date. It
requested detailed information on facility and process characteristics, chemical consumption,
worker activities related to chemical exposure, water consumption, and wastewater discharges.
The Observer Data Sheet was used by an on-site observer to collect data during the Performance
3 In addition, Electrochemicals, LeaRonal, and Solution Technology Systems provided information on
proprietary chemical ingredients to the project. This is discussed further in Section 1.3.5.
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1.3 CTSA METHODOLOGY
Demonstration. In addition to ensuring that the performance test was performed according to the
agreed upon test protocol, the on-site observer collected measured data, such as bath temperature
and process line dimensions, and checked survey data for accuracy. Appendix A contains copies
of the IPC Workplace Practices Questionnaire, the Facility Background Information Sheet, and
the Observer Data Sheet forms.
Table 1.2 lists the number of PWB manufacturing facilities that completed the IPC
Workplace Practices Questionnaire (original forms modified for the Performance Demonstration)
by type of MHC process, excluding responses with poor or incomplete data. Of the 59 responses
to the questionnaire, 25 were Performance Demonstration test sites.
Table 1.2 Responses to the Workplace Practices Questionnaire
MHC Technology
Electroless Copper
Carbon
Conductive Polymer
Graphite
No* of Responses
36
2
1
4
MHC Technology
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
No. of Responses
1
2
13
Information from the pollution prevention and control technologies survey conducted by
the DfE PWB Project was also used in the CTSA. These data are described in detail in the EPA
publication, Printed Wiring Board Pollution Prevention and Control: Analysis of Survey Results
(EPA, 1995a).
1.3.5 Project Limitations
There are a number of limitations to the project, both because of the project's limited
resources, the predefined scope of the project, and data limitations inherent to risk
characterization techniques. Some of the limitations related to the risk, competitiveness and
conservation components of the CTSA are summarized below. More detailed information on
limitations and uncertainties for a particular portion of the assessment is given in the applicable
sections of this document. A limitation common to all components of the assessment is that the
MHC chemical products assessed in this report were voluntarily submitted by participating
suppliers and may not represent the entire MHC technology market. For example, the electroless
nickel and lomerson technologies were not evaluated in the CTSA.
Bisk
The risk characterization is a screening level assessment of multiple chemicals used in
MHC technologies. The focus of the risk characterization is on chronic (long-term) exposure to
chemicals that may cause cancer or other toxic effects, rather than on acute toxicity from brief
exposures to chemicals. The exposure assessment and risk characterization use a "model
facility" approach, with the goal of comparing the exposures and health risks of the MHC process
alternatives to the baseline electroless copper technology. Characteristics of the model facility
were aggregated from questionnaire data, site visits, and other sources. This approach does not
result in an absolute estimate or measurement of risk.
1-12
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1.3 CTSA METHODOLOGY
In addition, the exposure and risk estimates reflect only a portion of the potential
exposures within a PWB manufacturing facility. Many of the chemicals found in MHC
technologies may also be present in other process steps of PWB manufacturing and other risk
concerns for human health and the environment may occur from other process steps. Incremental
reduction of exposures to chemicals of concern from an MHC process, however, will reduce
cumulative exposures from all sources in a PWB facility, provided that increased production does
not increase plant-wide pollution.
Finally, information presented in this CTSA is based on publicly-available chemistry data
submitted by each of the participating suppliers, as well as proprietary data submitted by
Electrochemicals, LeaRonal, and Solution Technology Systems. W.R. Grace was preparing to
submit proprietary data for the conductive ink technology when it was determined that this
information was no longer necessary because risk from the conductive ink technology could not
be characterized. The other suppliers participating in the project (Atotech, Enthone-OMI,
MacDermid, and Shipley) declined to provide proprietary information. The absence of
information on proprietary chemical ingredients is a significant source of uncertainty in the risk
characterization. Risk information for proprietary ingredients, as available, is included in this
CTSA, but chemical identities and chemical properties are not listed.
Competitiveness
The Performance Demonstration was designed to provide a snapshot of the performance of
different MHC technologies. The test methods used to evaluate performance were intended to
indicate characteristics of a technology's performance, not to define parameters of performance or
to substitute for thorough on-site testing. Because the test sites were not chosen randomly, the
sample may not be representative of all PWB manufacturing facilities in the U.S. (although there
is no specific reason to believe they are not representative).
The cost analysis presents comparative costs of using an MHC technology in a model
facility to produce 350,000 ssf of PWBs. As with the risk characterization, this approach results
in a comparative evaluation of cost, not an absolute evaluation or determination. The cost
analysis focuses on private costs that would be incurred by facilities implementing a technology.
It does not evaluate community benefits or costs, such as the effects on jobs from implementing a
more efficient MHC technology. However, the Social Benefits/Costs Assessment (see Section
7.2) qualitatively evaluates some of these external (i.e., external to the decision-maker at a PWB
facility) benefits and costs.
The regulatory information contained in the CTSA may be useful in evaluating the benefits
of moving away from processes containing chemicals that trigger compliance issues. However,
this document is not intended to provide compliance assistance. If the reader has questions
regarding compliance concerns, they should contact their federal, state, or local authorities.
Conservation
The analysis of energy and water consumption is also a comparative analysis, rather than
an absolute evaluation or measurement. Similar to the cost analysis, consumption rates were
estimated based on using an MHC technology in a model facility to produce 350,000 ssf of PWB.
1-13
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1.4 ORGANIZATION OF THIS REPORT
1.4 ORGANIZATION OF THIS REPORT
This CTSA is organized into two volumes: Volume I summarizes the methods and
results of the CTSA; Volume II consists of appendices, including detailed chemical properties
and methodology information, and comprehensive results of the risk characterization.
Volume I is organized as follows:
• Chapter 2 gives a detailed profile of the MHC use cluster, including process descriptions
of the MHC technologies evaluated in the CTSA and the estimated concentrations of
chemicals present in MHC chemical baths.
• Chapter 3 presents risk information, beginning with an assessment of the sources, nature,
and quantity of selected environmental releases from MHC processes (Section 3.1);
followed by an assessment of exposure to MHC chemicals (Section 3.2) and the potential
human health and ecological hazards of MHC chemicals (Section 3.3). Section 3.4
presents quantitative risk characterization results, while Section 3.5 discusses process
safety concerns.
• Chapter 4 presents competitiveness information, including Performance Demonstration
results (Section 4.1), cost analysis results (Section 4.2), regulatory information (Section
4.3), and international market information (Section 4.4).
• Chapter 5 presents conservation information, including an analysis of water and other
resource consumption rates (Section 5.1) and energy impacts (Section 5.2).
• Chapter 6 describes additional pollution prevention and control technology opportunities
(Sections 6.1 and 6.2, respectively).
• Chapter 7 organizes data collected or developed throughout the CTSA in a manner that
facilitates decision-making. Section 7.1 presents a summary of risk, competitiveness and
conservation data. Section 7.2 assesses the social benefits and costs of implementing an
alternative as compared to the baseline. Section 7.3 provides summary profiles for the
baseline and each of the MHC alternatives.
1-14
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REFERENCES
REFERENCES
Kincaid Lori E Jed Meline and Gary Davis. 1996. Cleaner Technologies Substitutes
Assessment: A Methodology & Resource Guide. EPA Office of Pollution Prevention and
Toxics. Washington, D.C. EPA 744-R-95-002. December.
Microelectronics and Computer Technology Corporation (MCC). 1993. Environmental
Consciousness: A Strategic Competitiveness Issue for the Electronics and Computer
Industry. March.
Microelectronics and Computer Technology Corporation (MCC). 1994. Electronics Industry
Environmental Roadmap. December.
US Environmental Protection Agency (EPA). 1995a. Printed Wiring Board Pollution
Prevention and Control: Analysis of Survey Results. Design for the Environment Printed
Wiring Board Project. EPA Office of Pollution Prevention and Toxics. Washington,
D.C. EPA 744-R-95-006. September.
US Environmental Protection Agency (EPA). 1995b. "Printed Wiring Board Case Study 1:
Pollution Prevention Work Practices." Pollution Prevention Information Clearinghouse
(PPIC). Washington, D.C. EPA 744-F-95-004. July.
US Environmental Protection Agency (EPA). 1995c. "Printed Wiring Board Case Study 2.
On-Site Etchant Regeneration." Pollution Prevention Information Clearinghouse (PPIC).
Washington, D.C. EPA744-F-95-005. July.
U S Environmental Protection Agency (EPA). 1995d. Federal Environmental Regulations
Affecting the Electronics Industry. EPA Office of Pollution Prevention and Toxics.
Washington, D.C. EPA 744-B-95-001. September.
US Environmental Protection Agency (EPA). 1995e. Printed Wiring Board Industry and Use
Cluster Profile. Design for the Environment Program Printed Wiring Board Project.
EPA Office of Pollution Prevention and Toxics. Washington, D.C. EPA 744-R-95-005.
September.
US Environmental Protection Agency (EPA). 1996a. "Printed Wiring Board Project:
Opportunities for Acid Recovery and Management." Pollution Prevention Information
Clearinghouse (PPIC). Washington, D.C. EPA 744-F-95-009. September.
US Environmental Protection Agency (EPA). 1996b. "Printed Wiring Board Project: Plasma
Desmear: A Case Study." Pollution Prevention Information Clearinghouse (PPIC).
Washington, D.C. EPA744-F-96-003. September.
US Environmental Protection Agency (EPA). 1996c. "Printed Wiring Board Project: A
Continuous-Flow System for Reusing Microetchant" Pollution Prevention Information
Clearinghouse (PPIC). Washington, D.C. EPA 744-F-96-024. December.
1-15
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REFERENCES
U.S. Environmental Protection Agency (EPA). 1997. Implementing Cleaner Technologies in
the Printed Wiring Board Industry: Making Holes Conductive. EPA Office of Pollution
Prevention and Toxics. Washington, D.C. EPA744-R-97-001. February.
1-16
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Chapter 2
Profile of the Making Holes Conductive Use Cluster
This section of the Cleaner Technologies Substitute Assessment (CTSA) describes the
technologies that comprise the making holes conductive (MHC) use cluster. A use cluster is a
set of chemical products, technologies, or processes that can substitute for one another to perform
a particular function. In this case, the function is "making holes conductive" and the set of
technologies includes electroless copper, carbon, conductive polymer, graphite, non-
formaldehyde electroless copper, organic-palladium, and tin-palladium. Information is also
provided for a conductive ink technology, which can be used to perform the MHC function on
double-sided boards, but not multi-layer boards.
Section 2.1 presents process descriptions for each of the MHC technologies and describes
the chemical composition of MHC chemical products that were evaluated in the CTSA. Section
2.2 briefly describes additional technologies that may be used to perform the MHC function, but
were not evaluated. Section 2.3 summarizes the market for MHC technologies, including
information on the total market value of MHC chemicals, and the market shares of electroless
copper processes as compared to the technologies.
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF MHC TECHNOLOGIES
This section introduces the MHC technologies evaluated in the CTSA and details the
MHC process sequences, including descriptions of individual process baths in each of the
technologies. Typical operating conditions and operating and maintenance procedures are
described in an overview of the MHC manufacturing process. The chemical processes occurring
in each bath are detailed along with additional process information specific to each technology.
Finally, this section describes the sources of bath chemistry information, methods used for
summarizing that information, and use of publicly-available bath chemistry data.
2.1.1 Substitutes Tree of MHC Technologies
Figure 2.1 depicts the eight MHC technologies evaluated in the CTSA. Because the
function of MHC can be performed using any of these technologies, these technologies may
"substitute" for each other in PWB manufacturing. Except for the conductive ink technology,
which is a screen printing technology, each of the MHC technologies is a wet chemistry process,
consisting of a series of chemical process baths, often followed by rinse steps, through which a
rack of panels is passed to apply the conductive coating or seed layer.
For each of the wet chemistry technologies, the process baths depicted in the figure
represent an integration of the various commercial products offered within a category. For
example, chemical suppliers to the PWB industry submitted product data for six different
electroless copper processes for evaluation in the CTSA, and these and other suppliers offer
additional variations to the electroless copper processes that may have slightly different bath
2-1
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
2-2
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
chemistries or bath .sequences. Figure 2.1 lists the types of baths in a typical, or generic,
electroless copper line, but the types of baths in an actual line may vary.
2.1.2 Overview of MHC Technologies
MHC technologies typically consist of a series of sequential chemical processing tanks
separated by water rinse stages. The process can either be operated in a vertical, non-
conveyorized immersion-type mode or in a horizontal, conveyorized mode. In either mode,
selected baths may be operated at elevated temperatures to facilitate required chemical reactions,
or agitated to improve contact between the panels and the bath chemistry. Agitation methods
employed by PWB manufacturers include panel agitation, air sparging, and fluid circulation
pumps.
Most process baths are followed by a water rinse tank to remove drag-out, the clinging
film of process solution covering the rack and boards when they are removed from a tank.
Rinsing is necessary to provide a clean panel surface for further chemical activity, while
preventing chemical drag-out which may contaminate subsequent process baths. PWB
manufacturers employ a variety of rinse water minimization methods to reduce rinse water usage
and consequent wastewater generation rates. The nature and quantity of wastewater generated
from MHC process lines are discussed in Section 3.1, Source Release Assessment, while rinse
water reduction techniques are discussed in Section 6.1, Pollution Prevention.
In non-conveyorized mode, drilled multi-layered panels are desmeared, loaded onto a
rack, and run through the MHC process line. Racks may be manually moved from tank to tank,
moved by a manually or automatically controlled hoist, or moved by other means. Process tanks
are usually open to the atmosphere. To reduce volatilization of chemicals from the bath or
worker exposure to volatilized chemicals, process baths may be equipped with a local ventilation
system, such as a push-pull system, bath covers for periods of inoperation, or floating plastic
balls. Conveyorized systems are typically fully enclosed, with air emissions vented to a control
technology or to the atmosphere outside the plant.
Regardless of the mode of operation, process baths are periodically replenished to either
replace solution lost through drag-out or volatilization, or to return the concentration of
constituents in the bath to within acceptable limits. During the course of normal operations, bath
chemistry can be altered by chemical reactions occurring within the bath, or by contamination
from drag-out. Bath solution may be discarded and replaced with new solution, depending on
analytical sampling results, the number of panel surface square feet (ssf) processed, or the
amount of time elapsed since the last change-out. Process line operators may also clean the tank
or conveyorized equipment during bath change-out operations.
Some process baths are equipped with filters to remove participate matter, such as copper
particles plated out of solution due to the autocatalytic nature of the electroless copper process
(discussed in the following section). Process line operators or other personnel periodically
replace the bath filters based on criteria such as analytical sampling results from the process
baths, elapsed time, or volume of product produced.
2-3
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
2.1.3 Chemistry and Process Descriptions of MHC Technologies
This section describes in detail the processes for adding a conductive coating to the
substrate surfaces of PWB drilled through-holes. A brief description of the chemical
mechanisms or processes occurring in each of the process steps along with other pertinent
process data such as substrate compatibilities and modes of operation (e.g., non-conveyorized or
conveyorized) are presented for each technology. For technologies with more than one chemical
supplier (e.g., electroless copper, graphite, and tin-palladium), a process description for each
chemical product line was developed in consultation with the chemical supplier, and then
combined to form a generic process description for that technology. Notable differences in the
chemical mechanisms or processes employed in a single product line from that of the generic
process are detailed.
Electroless Copper
Electroless copper has been the standard MHC method used in the manufacture of
double-sided and multi-layered boards. A palladium/tin colloid is adsorbed onto the through-
hole walls, which then acts as the catalyst for the electroless plating of copper. The autocatalytic
copper bath uses formaldehyde as a reducing agent in the principle chemical reaction that applies
a thin, conductive layer of copper to the nonconducting barrels of PWB through-holes.
Electroless copper processes are typically operated in a non-conveyorized mode and are
compatible with all types of substrates and desmear processes.
Figure 2.2 is a flow diagram of the process baths in a generic electroless copper process.
The following is a brief description of each of the process steps provided by technology suppliers
(Wood, 1995a; Bayes, 1995a; Thorn, 1995a) shown in the flow diagram.
Step 1: Grease and contaminants are removed from the through-hole walls in a
cleaning/conditioning solution. The solution prepares the through-hole surfaces
for plating and facilitates the adhesion of the palladium catalyst.
Step 2: A microetch solution, which typically consists of dilute hydrochloric or sulfuric
acid, etches the existing copper surfaces to remove any contaminants or oxides to
ensure good copper-to-copper adhesion at all of the copper interconnect points.
Step 3: Etched panels are processed through a predip solution which is chemically similar
to that of the palladium catalyst and is used to protect the catalyst bath from
harmful drag-in.
Step 4: The catalyst, consisting of a colloidal suspension of palladium/tin in solution,
serves as the source of palladium particles. The palladium particles adsorb onto
the glass and epoxy surfaces of the substrate from the colloidal solution, forming a
catalytic layer for copper plating.
Step 5: An accelerator solution prepares the surface for copper plating by chemically
removing, or accelerating, the protective tin coating from the palladium particles,
exposing the reactive surface of the catalyst.
2-4
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Figure 2.2 Generic Process Steps for the Electroless Copper Technology
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palladium catalyst. The electroless copper bath is an alkaline solution containing
a source of copper ions, a chelator to keep the copper ions solubilized, a stabilizer
to prevent the copper solution from plating out, and a formaldehyde reducing
agent. Several chelating agents are currently used in electroless copper baths,
including ethylenediaminetetraacedic acid (EDTA), quadrol, and tartrate. The
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Step 7: A weak acidic solution neutralizes residual copper solution from the board and
prepares the surface for dry film application.
Step 8: The copper surfaces are treated with an anti-tarnish solution to prevent oxidation
and further prepare the panel surfaces for dry film lamination. This process step
may not be needed with some processes; it is required primarily in cases where
long delays in panel processing are encountered.
Several chemical manufacturers market electroless copper processes for use in MHC
applications. Figure 2.3 lists the process baths for each of the electroless copper processes
provided by chemical suppliers for evaluation in the CTSA. The processes differ slightly in
types of chelating agents or stabilizing compounds used, but all are similar to the electroless
copper process described above.
2-5
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Figure 2.3 Electroless Copper Processes Submitted by Chemical Suppliers
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Carbon
Carbon processes utilize a suspension of carbon black particles to deposit a conductive
layer of carbon onto the substrate surface. The spherical carbon black particles form an
amorphous, or noncrystalline, structure of randomly scattered crystallites, which create a
conductive layer. The process is typically operated in a conveyorized fashion, but can be
modified to be run in a non-conveyorized mode. It is compatible with all common substrates
and, in the conveyorized mode, can be fed directly into a put-sheet dry-film laminator (Wood,
1995b).
Figure 2.4 is a flow diagram of the process baths in a generic carbon process. The
following is a brief description of each of the process steps provided by technology suppliers
(Retalick, 1995; Wood, 1995b; Gobhardt, 1993) shown in the flow diagram.
Step 1: A cleaner solution containing a cationic wetting agent removes oil and debris
from the panel while creating a positive charge on the glass and epoxy surfaces of
the drilled through-hole.
Step 2: Carbon black particles are adsorbed onto the positively charged substrate surface
from the alkaline carbon black dispersion. The adsorbed particles form an
amorphous layer of carbon that coats the entire panel including the through-hole
surfaces.
2-6
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2.1 CHEMISTRY AMP PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Figure 2.4 Generic Process Steps for the Carbon Technology
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carbon layer.
Step 4: A conditioner bath cleans and conditions the panel surface and prepares the panel
for a second layer of carbon black.
Steps 5-6: Steps 2-3 are repeated using a similar carbon bath which deposits a second layer
of carbon Hack particles onto the exposed surfaces of the panel. After the second
drying step, a porous layer of carbon black covers the entire panel, including the
outside .copp.er surfaces and the inner-layer interconnects. This carbon layer must
be removed from the copper surfaces before the panel is electroplated or
laminated with dry film in subsequent process steps.
Step 7: A copper micro.etch penetrates the porous layer of carbon and attacks the copper
layer underneath, lifting the unwanted carbon off the copper surfaces while
cleaning the copper surface for plating. Because the microetch does not attack the
glass and epoxy surfaces, it leaves the carbon-coated glass and epoxy surfaces
intact. The etched copper surfaces can also be directly laminated with a dry-film
photoresist without any additional processing.
The non-conveyorized version of carbon is operated in an identical fashion to the process
described above. The carbon direct-plate process may be operated in a single or double pass
configuration depending on the complexity of the product. The double-pass system described
above ensures a high level of reliability for high multi-layer, high aspect ratio hole applications.
2-7
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
A single-pass, conveyorized system has also been developed and is now being utilized in less
rigorous process applications.
Conductive Ink
Conductive ink MHC processes are effective with double-sided, surface mount
applications. This type of process utilizes a mechanical screen printing process to deposit a
special conductive ink into the through-holes of a PWB. Possible screen materials include
stainless steel or polyester, with the former being preferred for high volume or fine registration
applications. Several types of inks have been developed, each with unique properties (e.g.,
solderability, conductivity, cost, etc.), to meet the demands of each specific application. This
process is compatible with most common types of laminate including epoxy glass and phenolic
paper boards.
Figure 2.5 is a process flow diagram of the process steps in a generic conductive ink
process. The following is a brief description of each of the process steps provided by technology
suppliers (Peard, 1995; Holmquest, 1995) shown in the flow diagram.
Step 1: A microetch solution etches the surface of the copper laminate, removing oil and
other contaminants, providing a good copper-to-ink connection.
Step 2: An air knife removes any residual chemistry from the PWB panels before the
panels are dried in a oven. The panels must be dried completely to remove any
moisture from the substrate before screening.
Step 3: The screen with the image of the panel to be processed is created for each side of
the panel. Screen material, mesh size, and screen tension are all factors that must
be considered. After the type of screen is selected, the printing image is
transferred to the screen, using a combination of direct and indirect emulsions, to
achieve an emulsion thickness sufficient for ink deposition. A platen, with holes
slightly larger than the drilled holes, is created to both support the panels while
screening, and to allow uniform ink flow through each hole. Other parameters
such as ink viscosity, screen off-contact distance, and squeegee speed and
hardness are all interdependent and must be optimized.
Step 4: A squeegee is passed over the surface of the ink-flooded screen, effectively
forcing the ink through the screen and into the drilled holes of one side of the
panel. Squeegee angle and speed, ink viscosity, and through-hole size as well as
other factors all contribute to the amount of ink forced into the through-hole.
After processing, the screen may be reclaimed for reuse with another image. For
more information on screen reclamation refer to the Cleaner Technologies
Substitutes Assessment, Industry: Screen Printing (EPA, 1994).
Step 5: Hot air drying removes solvent from the ink deposit, partially curing the ink.
Solvent must be completely removed from the ink prior to curing in order to
prevent voiding and bubbles which develop as residual solvent tries to escape.
2-8
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Figure 2.5 Generic Process Steps for the Conductive Ink Technology
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Step 6: The screened panel is flipped over and the screening step described in Step 4 is
repeated. Ink should completely fill the hole, without the presence of voids, and
should overlap the copper on both top and bottom surfaces to promote good
conductivity. The second screening step is typically needed to get the required
amount of ink into the through-hole, but may not be necessary. The second
screening step may be eliminated through the use of a vacuum while screening
which allows the use of a higher-viscosity ink that improves ink coverage of the
through-hole.
Step 7: Hot air or infrared methods are used to first dry and then cure the conductive ink,
leaving the ink solvent-free while cross-linking the thermoset resins that form the
final polymer.
2-9
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2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Steps 8-11: A final coating of soldermask is applied to cover the printed through-holes on
both sides of the PWB, protecting them against oxidation and potential physical or
chemical damage. The solder mask is typically applied using a screen printing
and drying sequence similar to that described in Steps 4-5. The process is then
repeated for the reverse side.
Conductive Polymer
This MHC process forms a conductive polymer layer, polypyrolle, on the substrate
surfaces of PWB through-holes. The polymer is formed through a surface reaction during which
an immobilized oxidant reacts with an organic compound in solution. The conductive polymer
process can be operated horizontally and is compatible with most common substrates as well as
traditional etch-back and desmear processes. Because of the relative instability of the polymer
layer, the process may be operated with a flash-plating step, but this step was not evaluated hi the
risk characterization (Boyle, 1995c; Boyle, 1995d).
The process steps for the conductive polymer process are shown in Figure 2.6. The
following is a brief description of each of the process steps provided by technology suppliers
(Boyle, 1995c; Boyle, 1995d; Meyer et al., 1994) shown in the flow diagram.
Figure 2.6 Generic Process Steps for the Conductive Polymer Technology
Microetch I
I. ^T' '.*> .
2 Cleaner/ 1
Conditioner 1
w
3 Catalyst [
. ; ifl - -'. ' " ~
4 Conductive 1
Polymer 1
•tyj^V' -.- : :•:
Microetch 1 •.
•-i'V^^-- '• '<"•-'' ' "..-' "•
6 Copper I",
Flash 1
• • •
Step 1:
Step 2:
The microetch solution lightly etches the exposed copper surfaces of the panel,
including the inner layer copper interconnects, to remove any chemical
contamination and metal oxides present.
A cleaner/conditioner step removes any oil or debris from the hole and coats the
glass and epoxy surfaces of the substrate with a water-soluble organic film. The
organic film is designed to both adhere to the substrate surfaces of the hole barrel
and be readily oxidized by permanganate.
2-10
-------
Step 3:
Step 4:
Step 5:
Step 6:
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
The film is then exposed to a permanganate catalyst solution, which deposits
manganese dioxide (MnO2) through the oxidation of the organic film. The MnO2
deposition is selective, only reacting with the film-coated surfaces of the substrate.
This is important, since the final formation of the polymer occurs only on the
glass and epoxy surfaces where MnO2 is present, not on the copper surfaces where
interconnect defects could occur.
Polymerization occurs when a weakly acidic conductive polymer solution
containing a pyrolle monomer is applied to the substrate coated with MnO2. The
polymerization of pyrolle, which forms the conductive polymer polypyrolle,
continues until all of the MnO2 oxidant is consumed. The resulting layer of
conductive polymer on the substrate is thin and relatively unstable, especially in
alkaline solutions.
A microetch solution removes oxides and chemical contamination from all
exposed copper surfaces, preparing them for flash-plating.
The conductive polymer-covered through-holes are flash plated with copper in an
acid copper electroplating bath. A thin layer of copper plating is sufficient to
prepare the panel for lamination with dry film photoresist and subsequent pattern-
plating, or the panel can be fully panel plated. Flash plating may not be required
in instances where minimal hold times are experienced between the formation of
the polymer and the pattern plating step.
The conductive polymer process has been successfully operated in Europe, and has been recently
adopted in the U.S.
Graphite
Graphite processes provide for the deposition of another form of carbon—graphite—onto
the substrate surfaces of the through-holes, in a process similar to the carbon process described
above. Graphite has a three-dimensional, crystalline structure as opposed to the amorphous,
randomly arranged structure found in carbon black (Carano, 1995). One notable difference
between the carbon and graphite processes is that the graphite system requires only one pass of
the panel through the graphite bath to achieve sufficient coverage of the through-hole walls prior
to electroplating.
Figure 2.7 is a flow diagram of the process baths in a generic graphite process. The
following is a brief description of each of the process steps provided by technology suppliers
(Thorn, 1995b; Carano, 1995; Bayes, 1995c) shown hi the flow diagram.
Step 1: A cleaner/conditioner solution removes oil and debris from the panel and creates a
slight positive charge on the exposed surfaces of the through-hole.
Step 2: Graphite particles are flocculated onto the substrate surfaces of the through-hole.
The conductive graphite layer coats the entire panel, including the nonconductive
substrate surfaces, the copper surfaces of the outside layers, and the interconnects.
2-11
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Figure 2.7 Generic Process Steps for the Graphite Technology
Step 3:
Step 4:
1 Cleaner/
Conditioner
Graphite
Fixer
(optional)
3 Air Knife/
Dry
Microetch
An air knife removes the excess graphite dispersion from the through-holes before
a hot air oven dries the conductive graphite layer, causing it to polymerize. After
drying, a porous layer of graphite coats both the copper surfaces and the substrate
surfaces of the through-hole. The graphite must be removed from the copper
surfaces before they are plated with copper or the panels are laminated with dry
film.
A copper microetch undercuts the porous layer of graphite, removing a thin layer
of copper underneath, lifting the unwanted graphite off the copper surfaces while
cleaning the copper surface for plating. Because the microetch does not attack the
glass and epoxy surfaces, it leaves the graphite-coated glass and epoxy surfaces
intact. The etched copper surfaces can also be directly laminated with a dry-film
photoresist without any additional processing.
The graphite process typically is operated in a conveyorized mode but can also be
modified for non-conveyorized applications. When operated in non-conveyorized mode, a fixer
step (the optional step shown in Figure 2.7) is employed directly after the graphite bath and
before the hot air drying. The fixer step promotes the uniform coating of the hole walls by
causing the graphite coating to polymerize and adhere to the substrate. This is necessary to
counteract gravity, which will cause the carbon to deposit more heavily along the lower, bottom
side of the holes.
A fixer step can also be useful in conveyorized process modes where high aspect ratio
holes (small diameter holes in thick panels) are being manufactured. The fixer causes the
graphite to cover the entire hole barrel evenly and prevents the solution from accumulating at one
end.
2-12
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Non-Formaldehyde Electroless Copper
This process is a vertical, non-conveyorized immersion process that allows the
electroless deposition of copper onto the substrate surfaces of a PWB without the use of
formaldehyde. The process uses hypophosphite in place of the standard formaldehyde as a
reducing agent in the electroless copper bath. The hypophosphite electroless bath is not
autocatalytic, which reduces plate-out concerns, and is self-limiting once the palladium catalyst
sites have been plated. Once a thin layer of copper is applied, the panel is placed under an
electrical potential and electroplated while still in the bath, to increase the copper deposition
thickness.
Figure 2.8 is a flow diagram for a typical non-formaldehyde electroless copper process.
The following is a brief description of each of the process steps provided by the technology
suppliers (Retalick, 1995; Wood, 1995a; Wood, 1995b) shown in the flow diagram.
Figure 2.8 Generic Process Steps for the Non-Formaldehyde Electroless Copper
Technology
Steps 1-3:
Step 4:
1 Cleaner/
Conditioner
Microetch
I
|
Predip
Cata|yst
Accelerator
7 Electroless
Copper/
Copper Flash
Anti-Tarnish
Panels are cleaned, conditioned, microetched, and predipped in a chemical process
similar to the one described previously for electroless copper.
The catalyst solution contains a palladium/tin colloidal dispersion that seeds the
nonconductive surfaces of the drilled through-holes. Because the electroless
2-13
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
copper bath is not autocatalytic, the catalyst process is designed to maximize the
adsorption of palladium/tin, which ensures that adequate copper plating of the
substrate will occur.
Step 5: A hydrochloric acid postdip solution partially removes the residual tin, exposing
the palladium seeds.
Step 6: The accelerator oxidizes the remaining tin to a more conductive state, enhancing
the catalytic properties of the palladium layer, before the panel enters the
electroless plating bath.
Step 7: The electroless plating bath uses hypophosphite, instead of formaldehyde, to
promote the reduction of copper onto the palladium catalyzed surfaces. The
nonautocatalytic bath plates copper only in the presence of the palladium seeds.
Copper plating continues until all palladium surfaces have been covered, resulting
in a thin layer (10 to 15 micro inches) of copper covering the hole walls.
Additional copper is added to the thin initial deposit, creating a thicker copper
layer, by a flash-plating step. The flash-plating is typically performed directly hi
the electroless copper bath by placing copper anodes into the bath and applying an
electrical potential. Copper electroplating continues until a total of 80 to 100
micro inches of copper is present on the through-hole surfaces. The panels may
also be flash-plated in an acid copper plating bath, if desired.
Step 8: The copper surfaces are treated with an anti-tarnish solution to prevent oxidation
and further prepare the panel surfaces for dry film lamination. This process step
may not be needed with some processes; it is required primarily in cases where
long delays in panel processing are encountered.
This non-conveyorized immersion process is compatible with all substrate types but requires a
permanganate etchback process prior to desmear.
Organic-Palladium
Two types of alternatives use dispersed palladium particles to catalyze nonconducting
surfaces of PWB through-holes: organic-palladium and tin-palladium. In both of these
processes, the palladium particles are adsorbed from solution directly onto the nonconducting
substrate, creating a conductive layer that can be electroplated with copper. Palladium particles
dispersed in solution tend to agglomerate unless they are stabilized through the formation of a
protective layer, or colloid, which surrounds the individual palladium particles. The organic-
palladium process uses a water-soluble organic polymer to form a protective layer, or colloid,
around the palladium particles. The protective colloid surrounds the individual palladium
particles, preventing them from agglomerating while in solution. The organic-palladium
colloidal suspension is formed when the organic polymer complex and the palladium particles
are combined with a reducing agent. The resulting colloidal suspension must be kept under
reduction conditions to ensure colloidal stability. After the particles have been deposited onto
2-14
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
the board, the protective colloid is removed, making the layer of palladium particles conductive
(Boyles, 1995b; Boyles, 1995d).
Figure 2.9 is a flow diagram of the process baths in a generic organic-palladium process.
The following is a brief description of each of the process steps provided by technology suppliers
(Boyle, 1995a; Boyle, 1995b; Boyle, 1995d) shown in the flow diagram.
Figure 2.9 Generic Process Steps for the Organic-Palladium Technology
Step 1:
Step 2:
Step 3:
Step 4:
r—. : : :
/ * -^
-*' n c ~ ~* ,
' ~d~ V' ^
*- " ",,"**
/— " „ *
' ^ - J' *"
' \ f^!f
,/' / ~ '£•
'*«^
'1 '"* "'*" "
'' *~ , "*" '' r*"
" " ' " "
>' ~ *
"•'* .;-''
v*'""7 " >
/'"*" v "
^ifj /f • fa* #&
Cleaner
.',* ~~y^ -
2 Microetch
\ V" • .
3 Conditioner
y
4 Predip
y
5 Conductor
^
6 Postdip
,i -'
7 Acid Dip
1 ' . X
j *- ^ B ^ X^ '*!
»V~ " ' w*/ '•'
s ;// " > ' «- , " t
X •' ' • ' * ' " - '
Is'" -*1"
*v " .-V"
^X,"1 ^™ *"' •"•" t^
1* ^s
'f , '"
'' »•*" "
1" * ^ ^
/-.•' 'x'
~L r ""_",«"
' - •»
] - - .'-'' -•
J - >.%
,,<•'
A cleaner bath containing a cationic wetting agent removes oil and debris from the
panel while creating a positive charge on the glass and epoxy surfaces of the
drilled through-hole.
The microetch solution lightly etches the exposed copper surfaces of the panel,
including the inner layer copper interconnects, to remove any chemical
contamination and metal oxides present.
Upon entering the conditioner bath, the substrate surfaces of the PWB are
conditioned with a polymer film designed to bond effectively with both the
palladium-tin colloid and the palladium particles themselves. The film adsorbs
from an aqueous solution onto surfaces of the through-holes where it acts as an
adhesion promoter for the tin-palladium colloid, binding strongly to its surface.
The polymer film has no affinity for the copper surfaces, leaving them film-free.
Conditioned panels are processed through a predip solution that is chemically
similar to the following conductor bath. The predip wets the substrate surfaces
with a mild acidic solution and protects the conductor bath from harmful drag-in
chemicals.
2-15
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Step 5: During the conductor step, organic-palladium colloids adsorb onto the film-
covered glass and epoxy surfaces from a colloidal suspension. The adsorbed
colloidal particles form a nonconductive organic-palladium layer across the
substrate surfaces of the through-hole.
Step 6: A postdip solution removes the stabilizing organic sheath from the surface
deposition, uncovering the remaining palladium particles and making them
conductive. The polymer film layer bonds with the conductive palladium
particles, keeping them from returning to solution.
Step 7: A weak acid dip stabilizes the active palladium surface and prepares the
palladium-covered surface for electroplating.
Organic-palladium can be operated successfully in either conveyorized or non-conveyorized
modes. The process is compatible with all common substrates, including Teflon.
Tin-Palladium
Tin-palladium processes also make use of a palladium activation step. These processes
use tin to form the colloid with palladium. After the adsorption of the tin-stabilized palladium
colloid, the tin is removed, creating a layer of conductive palladium particles on the surface of
the substrate.
Figure 2.10 depicts the process baths in a generic tin-palladium process. The following is
a brief description of each of the process steps provided by technology suppliers (Thrasher, 1995;
Harnden, 1995a; Harnden, 1995b; Bayes, 1995a; Bayes, 1995b; Bayes, 1995c; Marks, 1996)
shown in the flow diagram.
Figure 2.10 Generic Process Steps for the Tin-Palladium Technology
; 1
. x ^ ' * 5
1 Cleaner/ I
Conditioner!
i "• *
Microetch
v **
3 Predip
"
]
v
1 - " " • "•
• -t .
4 Catalyst
- -,y .
5 Accelerator
^^ „ ' ^
V '-"' - "
« v
j \
r ' :'s-^
6 Acid Dip 1
2-16
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Steps 1-2: Panels are cleaned, conditioned, and microetched by a chemical process that is
similar to the process described in Steps 1-2 of the organic-palladium method
described previously.
Step 3: Etched panels are processed through a predip solution which is chemically similar
to that of the palladium catalyst and is used to protect the catalyst bath from
harmful drag-in.,
Step 4: Tin-palladium colloids adsorb from the colloidal suspension of the catalyst
solution onto the slightly charged through-hole surfaces. The adsorbed palladium
colloids form a relatively nonconductive coating on the substrate surfaces of the
through-hole.
Step 5: An accelerator solution typically removes the protective tin coating from the
tin/palladium layer, exposing the catalytic surface of the palladium particles,
making the layer conductive.
Step 6: A weak acid dip stabilizes the active palladium surface and prepares the
palladium-covered surface for dry film application and electroplating.
Many tin-palladium processes are similar up through Step 4, but use different methods to
optimize the conductivity of the palladium deposit. Figure 2.11 illustrates the process steps in
each tin-palladium product line submitted by chemical suppliers for evaluation in the CTSA.
Methods used to optimize the conductivity of the palladium layer are discussed below.
Figure 2.11 Tin-Palladium Processes Submitted by Chemical Suppliers
; -'"
& " A
'f ,V W
C-
,
>' r
" "• r
i
,, "\
, 4
i
v
i** «
pfojtssll
Conditioner
Predip
Catalyst
Accelerator
*•>,» 1 s-
Enhancer
Stabilizer
Microetch
High
Pressure
Water Rinse
' " *
V r
t
" 'f
- .1
f
•-[
LA
^ ^
"*
,
Process #2'
' Vrt
Cleaner/
Conditioner
III || || in ^^T"^
Microetch
Predip
Activator
Accelerator
Acid Dip
j f
S**
^:p
' - r
/~>
^f
^
, •; -";
Process #3 " ^ "'
1'.
*
- ~>- '
Mil . ,^ '-^
Microetch 1 / p-
r -V
Predip I/ " f~
| ^->
Catalyst 1 *' * s|7~
(^
x/ 1
Acid Dip 1 :
' » «r ^V ^
*•
-^ >_\, "
Process #4
Microetch
Predip
Catalyst
Accelerator
Acid Dip
tf ^ *
,'',' /
*.
"*"*' *
.-
/ ,
*
* ~ c
<
£
l '
^ ,
2-17
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
One method accelerates, or removes, the protective tin colloid from the palladium,
leaving a coating of fine palladium particles on the surface of the substrate. Sulfide is then
reacted with palladium to form a more stable chemical layer. Sulfidation of the palladium sites is
not selective to the substrate surfaces only, and will adsorb onto the exposed copper of the inner
layers. To prevent plating defects from occurring, a microetch step removes the adsorbed sulfide
from the exposed copper surfaces of the interconnects (Bayes, 1995b; Bayes, 1995c).
A second method converts the positively charged tin colloid to metallic tin, while
simultaneously reducing copper onto the surface of the new tin-palladium layer. Both reductions
are a result of a disproportionation reaction occurring under alkaline conditions and in the
presence of copper ions. The reduction of copper onto the tin-palladium layer creates an
electrically conductive palladium/tin/copper metallic coating that can be subsequently
electroplated to the desired specifications (Nargi-Toth, 1996).
A third method uses a chemical called vanillin in the formation of the tin-palladium
colloid. Vanillin will attach to most other molecules, except another vanillin molecule. As a
consequence, the vanillin on the surface of the palladium/tin colloid prevents the colloidal
suspension from agglomerating while also facilitating the deposition of the colloid onto the
substrate surface. The water-soluble vanillin is then removed along with the tin in the following
water rinse step. Copper ions are complexed with the palladium in an accelerator step, to form a
palladium/copper layer which is then chemically stabilized by a mild acid setter step (Harnden,
1995a; Harnden, 1995b).
2.1.4 Chemical Characterization of MHC Technologies
This section describes the sources of bath chemistry information, methods used for
summarizing that information, and use of publicly-available bath chemistry data. Publicly-
available information alone is used to assess exposure and risk because MHC chemical suppliers
have not fully provided proprietary bath chemistry data.1 This section does not identify any
proprietary ingredients.
Use of Publicly-Available Chemical Formulation Data
Assessment of releases, potential exposure, and characterizing risk for the MHC process
alternatives requires chemical-specific data, including concentrations for each chemical in the
various baths. Although some bath chemistry data were collected in the IPC Workplace
Practices Questionnaire, the decision was made not to use these data because of inconsistencies
hi responses to the questions pertaining to bath chemistry. Instead, the suppliers participating in
the Performance Demonstration each submitted publicly-available data on their respective
product lines. This information includes:
Three suppliers, Electrochemicals, LeaRonal, and Solution Technology Systems, have provided
information on proprietary chemical ingredients to the project. W.R. Grace had been preparing to provide
information on proprietary chemical ingredients in the conductive ink technology when it was determined that this
information was no longer necessary because risk from the conductive ink technology could not be characterized.
The other suppliers participating in the project (Atotech, Enthone-OMI, MacDermid, and Shipley) have declined to
provide proprietary information.
2-18
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Material Safety Data Sheets (MSDSs).
• Product Data Sheets.
• Patent data, in some cases.
MSDSs identify the chemicals in a supplier's product and Product Data Sheets describe
how those products are mixed together to make up the individual baths. The available patents for
the product lines were consulted to identify unlisted ingredients.
Table 2.1 presents all chemicals identified in MHC process lines and the MHC
technologies in which they are used. Methods for summarizing the publicly-available and other
supplier information and calculation of concentrations are described below.
Table 2.1 Non-Proprietary Chemicals and Associated MHC Technologies
Chemical i>ist
2-Ethoxyethanol
1,3-Benzenediol
IH-Pyrrole
2-Butoxyethanol Acetate;
Jutylcellusolve Acetate
Ammonia
Ammonium Chloride
Benzotriazole
Boric Acid
Carbon Black
Copper (I) Chloride; Copper
Copper Sulfate; or Cupric
Sulfate
Diethylene Glycol n-Butyl
Ether
Diethylene Glycol Ethyl Ether
Diethylene Glycol Methyl
Ether
Dimethylaminoborane
Dimethylformamide
ithanolamine;
Vfonoethanolamine;
2-Aminoethanol
Ethylene Glycol
ithylenediaminetetraacetic
Acid (EDTA)
Fluoroboric Acid; Sodium
Bifluoride
Formaldehyde
Formic Acid
Graphite
Hydrochloric Acid
Hydrogen Peroxide
Hydroxyacetic Acid
[sophorone
Etectroless
Copper
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Carbon
•
•
•
•
Conductive
Ink
•
•
.•
•
•
•
•
Condactive
Polymer
•
Graphite
•
•
•
'
•
Non-
Forraaldehycle
Electroless
Copper
•
•
•
QrganJc-
Palladium
•
Tint-
Palladium
•
•
•
•
•
•
•
2-19
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Chemical List
[sopropyl Alcohol; 2-Propanol
Lithium Hydroxide
m-Nitrobenzene Sulfonic Acid
Sodium m-
^Jitrobenzenesulfonate
Vfagnesium Carbonate
Methanol
)-Toluene Sulfonic Acid;
fosic Acid
'alladium
'alladium Chloride
'eroxymonosulfuric Acid;
Potassium Peroxymonosulfate
3henol-Formaldehyde
Copolymer
'hosphoric Acid
'otassium Bisulfate
'otassium Carbonate
'otassium Cyanide
'otassium Hydroxide
Potassium Persulfate
'otassium Sulfate
'otassiurn-Sodium Tartrate
Silver
Sodium Bisulfate
Sodium Carbonate
Sodium Chloride
Sodium Chlorite
Sodium Cyanide
Sodium Hydroxide
iodium Hypophosphite
Sodium Persulfate
Sodium Sulfate
Stannous Chloride; Tin (II)
Chloride
Sulfuric Acid
Fartaric Acid
'riethanolamine; or
2,2',2"-Nitrilotris Ethanol
'risodium Citrate 5.5-Hydrate;
Sodium Citrate
Vanillin
Electroless
Copper
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Carbon
•
•
•
•
Conductive
Ink
•
•
•
Conductive
Polymer
•
•
•
•
•
Graphite
•
•
•
•
Non-
Formaldehyde
Electroless
Copper
•
•
•
•
•
•
•
Orgaak-
PaUadium
•
•
•
•
•
Tin*
Palladium
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Determining Chemical Formulations
The first step in determining chemical formulations was to divide each supplier's product
lines into the basic bath steps identified in Section 2.1.3, Chemistry and Process Descriptions of
MHC Technologies, for each MHC technology. This was accomplished by consulting with
suppliers to determine the MHC technology in which each product is used, as well as the step(s)
2-20
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
in the process in which the product is used (i.e., in which bath). Then, the non-proprietary
chemicals in each bath were identified for each MHG process.
The individual chemical concentrations in the baths were calculated by:
Cb =(CCHEM)(CFoRM)(D)(1000cm3/L)
where:
Cb
CCHEM
CFORM
D
concentration of constituent in bath (g/L)
the chemical concentration, by weight, in the product, from MSDSs (%)
proportion of the product formulation volume to the total bath volume,
from Product Data Sheets (%)
density of the product (g/cm3)
An example calculation for the triethanolamine concentration hi the conditioner/cleaner
bath is shown below for one supplier's tin-palladium process. Each product's MSDS lists the
chemicals that are contained in that product on a weight percentage basis. For triethanolamine,
this is ten percent, or ten grams triethanolamine per 100 grams of product. The supplier's
Product Data Sheet then lists how much of that package is used in the total bath makeup on a
volume percentage basis: in this case, 25 percent, or 25 liters of product per 100 liters of the
total bath. The remaining volume in the bath is made up of deionized water. The MSDSs also
include the specific gravity or density of the product, which was multiplied by the weight and
volume percentages above to obtain the bath concentration for that constituent. (In some cases,
the Product Data Sheets list chemicals or product packages on a mass per volume basis. This
was multiplied by the weight percentage from the MSDS for that product package to obtain a
concentration in the bath.) The example calculation is shown here:
lOOg
After the MSDS and Product Data Sheet data were combined in the above manner for
each supplier's product line, a list of non-proprietary chemicals in each MHC technology
category (electroless copper, tin-palladium, etc.) was compiled. This list shows all chemicals
that might be in each bath, bytechnology, as well as the concentration range for each chemical.
However, some of the alternatives (e.g., electroless copper, graphite, and tin-palladium) have
more than one chemical supplier using different bath chemistries. It was decided to include all of
the identified chemicals in the formulations rather than selecting a typical or "generic" subset of
chemicals.
Estimated concentration ranges (low, high, and average) were determined based on the
publicly-available information and are presented in Appendix B. Concentrations are for each
bath in each MHC process alternative.
2-21
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Data Limitations
Limitations and uncertainties in the chemical characterization data arise primarily from
the use of publicly-available data which do not account for side reactions in the baths, and which
do not always contain a full disclosure of chemical ingredients or concentrations. Side reactions
in the baths may result in changing concentrations over time and/or formation of additional
chemicals in the baths. This information is not reflected in MSDSs or Product Data Sheets but
would affect bath concentrations over time.
MSDSs are required of industry by OSHA (29 CFR 1910.1200). This includes reporting
any hazardous chemicals (as defined in the regulation) making up at least one percent of a
products formulation, or at least 0.1 percent for carcinogens.2 Any other chemical must be
reported if its release poses a hazard, even if <1 percent (or <0.1 percent). There are two basic
limitations to using this data: 1) chemical identity may be withheld from an MSDS if claimed to
be a trade secret; and 2) because the MSDS is focused on human health concerns, chemicals
posing ecological hazards may not be included. Table 2.2 summarizes the available information
on hazardous and carcinogenic trade secret chemicals as provided on the supplier's MSDSs.
Table 2.2 Material Safety Data Sheet Trade Secret Information
MHC Technology
Electroless Copper (BASELINE)
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
No, of Trade Secret
Chemicals Listed as
Hazardous
3a
0
0
lb
0
30
le
No. of Trade Secret
Chemicals Listed as
Carcinogenic
0
0
0
0
0
ld
lf
No. of MSDSs
Reviewed
50
12
7
17
21
5
40
* Confidential ingredient 1: Cationicemulsifier-<10%. Confidential ingredient 2: 1-5%; oral 7460 mg/kg LD50
rat, skin 16 g/kg LD^, rabbit. Confidential ingredient 3: 1-5%, oral 350 mg/kg LD50 mouse.
b Confidential ingredient: surfactant-< 2% by weight.
c Confidential ingredient 1: 5-15%; considered to be "relatively non-hazardous"; toxicity data: oral > 6400 mg/kg
LDj0 rabbit. Confidential ingredient 2: 1-5%; toxicity data: oral 100 g/kg LD50 rat, oral 1040 mg/kg LD50 rabbit.
Confidential ingredient 3: 10-20%; toxicity data: IPR 5600 mg/kg LD50 MUS, INV 2350 mg/kg LD50 MUS.
d Confidential ingredient 2: listed as a Class 3 carcinogen by IARC. A Class 3 carcinogen, as defined by IARC, is
"not classifiable as to human carcinogenicity," which means that there is "inadequate or no evidence."
0 Confidential ingredient: Non-ionic surfactant - <3%.
f An MSDS for one of the tin-palladium technologies states, "This product may contain small amounts of chemicals
listed as being known to the State of California to cause cancer or birth defects or other reproductive harm, under the
California Safe Drinking Water and Toxic Enforcement Act of 1986. It does not contain sufficient amounts of such
chemicals to make it subject to federal rules on hazard communication for carcinogens administered by OSHA [29
CFR 1910.1200 (d), Reference (1)]." The reference to federal rules on hazardous communication for carcinogens
means that it is present at <0.1%.
OSHA requirements apply to a chemical product as sold by a product manufacturer or supplier. Thus, as
referred to here, "product formulation" refers to the concentration of chemical ingredients in an MHC chemical
product prior to being mixed with other products or water in a chemical bath.
2-22
-------
2.1 CHEMISTRY AND PROCESS DESCRIPTION OF THE MHC TECHNOLOGIES
Many of the weight percent data on the MSDSs were reported as a "<" or ">" value. In
these cases the reported value is assumed in estimating bath concentrations. For example, if "<
50 percent" was reported for a constituent on an MSDS, it is assumed that product contained 50
percent by weight of that constituent. Also, some data were reported as ranges. In these cases,
mid-points for the ranges are used to estimate bath concentrations (e.g., if 20 to 30 percent by
weight was reported on the MSDS, 25 percent by weight is assumed).
Some manufacturers did not account for the total mass in each product formulation on
their MSDS report, or the remaining mass was identified simply as "non-hazardous" material. In
these cases, the suppliers were contacted directly for further information on the constituents. As
noted previously, some suppliers have provided additional information on chemical ingredients
to the project, but others have not.
Finally, it should be noted that the bath concentrations are estimated and the actual
chemical constituents and concentrations will vary by supplier and facility. As part of the risk
characterization, two chemicals are assessed further in terms of sensitivity of the risk results to
the possible range of bath concentrations.
Chemical Properties
Appendix C contains chemical properties data for each of the non-proprietary chemicals
identified in MHC baths. For example, properties listed include molecular weight, vapor
pressure, solubility, Henry's Law Constant, and octanol-water partition coefficient. Basic
chemical properties information for each chemical is followed by a summary description of fate
and transport mechanisms for that chemical.
2-23
-------
2.2 ADDITIONAL MHC TECHNOLOGIES
2.2 ADDITIONAL MHC TECHNOLOGIES
The MHC technologies described in Section 2.1 represent the technologies that were
evaluated in this CTS A. However, additional MHC technologies exist which were not evaluated
in the CTS A for one or more of the following reasons:
• A product line was not submitted for the technology by any chemical supplier.
• The technology was not available to be tested in the Performance Demonstration.
• The technology has only recently been commercialized since the evaluation began or was
submitted too late to be included in the evaluation.
Despite not being evaluated, these technologies are important because they are alternative
methods for MHC that accomplish the removal of formaldehyde from PWB manufacturing,
which is a goal of members of the PWB industry. A brief description of two MHC technologies
not evaluated in this CTSA is presented below. Other technologies may exist, but they have not
been identified by the project.
2.2.1 Lomerson Process
The lomerson process utilizes the drilling operation itself as the mechanism to apply a
conductive layer of material to the substrate surface of drilled through-holes. The panels can
then be cleaned and etched as with other MHC processes before undergoing subsequent
manufacturing processes. Completed panels can be assembled and soldered using typical PWB
manufacturing methods.
In this process a drill bit is forced through the substrate and into a block of soft conductor
material, usually indium or an indium-alloy. While the bit is turning, conductive cuttings from
the block are carried up through the hole and smeared throughout the barrel of the drilled hole by
the turning drill bit. The smeared material forms the conductive coating required to connect the
different layers of the PWB. The lomerson process was described several years ago, but is still in
development. However, the process continues to generate interest due to its obvious efficiencies
(EPA, 1995).
2.2.2 Non-Formaldehyde Electroless Nickel
The electroless nickel process uses a non-formaldehyde reducing agent to deposit a
conductive coating of nickel into the barrels of drilled through-holes. The process is similar to
the other wet processes presented earlier in this chapter. It consists of a sequence of chemical
baths separated by water rinse steps through which previously drilled and desmeared PWB panels
are processed. The supplier recommended sequence of process steps are as follows:
• Conditioner.
• Microetch.
• Sensitizer.
• Activator.
• Dry.
2-24
-------
2.2 ADDITIONAL MHC TECHNOLOGIES
» Cleaner.
» Electroless nickel.
The non-formaldehyde electroless nickel process may be operated in either conveyorized
or non-conveyorized modes and is compatible with most types of substrates. While the
electroless nickel process is a mature technology (EPA, 1995) very few PWB facilities currently
use this technology. No suppliers submitted this technology at the beginning of the CTSA,
although one supplier came forward after the Performance Demonstration.
2-25
-------
2.3 MARKET PROFILE OF MHC TECHNOLOGIES
2.3 MARKET PROFILE OF MHC TECHNOLOGIES
The market for MHC chemicals is characterized as being very competitive with slim
profit margins, similar to the PWB manufacturing industry (Nargi-Toth, 1997). The industry
trade association, the Institute for Interconnecting and Packaging Electronic Circuits (IPC), has a
Technology Market Research Council (TMRC) that tracks market, management and technology
trends for the electronic interconnection industry. The TMRC publishes annually information on
the total value of chemicals used in producing PWBs and the total value of chemicals used hi
specific applications, such as plating, solder mask, etching, and imaging. Information on plating
chemicals is further broken down to include additive/full build copper, electroless copper,
electrolytic, etch back/desmear, and oxide process chemicals. Table 2.3 presents TMRC
chemical market data for 1985,1990, and 1995, including the total value of PWB chemicals and
the value of electroless copper chemicals. TMRC does not list market values for the alternative
MHC chemical products separately.
Table 2.3 Market Value of PWB and Electroless Copper Chemicals
Total Value of Chemicals Used to Produce PWBs
Value of Chemicals Used in Electroless Copper Process
(excluding basic chemicals)
Percent of Total Chemicals Market Held by Electroless
Copper Chemicals
1985
$336 million
$48 million
14%
i$n
$495 million
$60 million
12%
1995
$580 million
$52 million
9%
* Source: IPC Assembly Market Research Council Meeting and IPC Technology Market Research Council Meeting
materials provided by Christopher Rhodes/IPC.
For the three years shown hi Table 2.3, the market value of PWB chemicals increased
between 1985 and 1995, but the market value of electroless copper chemicals peaked in 1990
prior to a decline hi 1995. Part of the decline may be due to the increased use of the MHC
alternatives hi this decade.
Until the latter half of the 1980s, all PWB shops were using an electroless copper process
to perform the MHC function (EPA, 1995). Circuit Center in Dayton, Ohio was one of the first
U.S. PWB facilities to use an MHC alternative for full-scale production. Circuit Center began
beta testing a carbon technology in the mid-to-late 1980s, went to full scale use of the technology
hi 1989, and has since implemented a graphite technology (Kerr, 1997). By 1995, one supplier
estimates 80 percent of shops were using electroless copper, with the rest using mainly carbon,
graphite, or tin-palladium (Nargi-Toth, 1997). Another supplier estimates the current market
value of the MHC alternatives at about $7 to $8 million, with carbon and graphite technologies
accounting for about $5 to $5.5 million of that market (Carano, 1997). Currently, the first full-
scale conductive polymer line hi the U.S. is being installed by H-R Industries in Richardson,
Texas.
2-26
-------
REFERENCES
REFERENCES
Bayes, Martin. 1995a. Shipley Company. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. June 1.
Bayes, Martin. 1995b. Shipley Company. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. November 27.
Bayes, Martin. 1995c. Shipley Company. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. December 15.
Boyle, Mike. 1995a. AtotechU.S.A., Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. May 16.
Boyle, Mike. 1995b. Atotech U.S.A., Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. July 7.
Boyle, Mike. 1995c. Atotech U.S.A., Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. November 28.
Boyle, Mike.' 1995d. AtotechU.S.A., Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. November 29.
Carano, Michael. 1995. Electrochemicals, Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. December 12.
Carano, Michael. 1997. Electrochemicals, Inc. Personal communication with Lori Kincaid, UT
Center for Clean Products and Clean Technologies. April 8.
Gobhardt, John. 1993. "The Blackhole Process." Presented at NEC A'93 Conference. March
24.
Harnden, Eric. 1995 a. Solution Technology Systems. Personal communication with Jack
Geibig, UT Center for Clean Products and Clean Technologies. August 9.
Harnden, Eric. 1995b. Solution Technology Systems. Personal communication with Jack
Geibig, UT Center for Clean products and Clean Technologies. November 29.
Holmquest, John. 1995. Dyna Circuits. Personal communication with Jack Geibig, UT Center
for Clean Products and Clean Technologies. December 12.
Kerr, Michael. 1997. Circuit Center, Inc. Personal communication with Lori Kincaid, UT
Center for Clean Products and Clean Technologies. April 8.
Marks, David. 1996. LeoRonal, Inc. Personal communication with Jack Geibig, UT Center for
Clean Products and Clean Technologies. February 8.
2-27
-------
REFERENCES
Meyer, H., RJ. Nicholas, D. Schroer and L. Stamp. 1994. "The Use of Conductive Polymer and
Collards in the Through-Hole Plating of Printed Circuit Boards." Electrochemical
ACTA. Vol. 39, No. 8/9, pp. 1325-1338.
Nargi-Toth, Kathy. 1996. Enthone-OMI, Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. February 14.
Nargi-Toth, Kathy. 1997. Enthone-OMI, Inc. Personal communication with Lori Kincaid, UT
Center for Clean Products and Clean Technologies. April 3.
Peard, David. 1995. W.R. Grace and Co. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. December 7.
Retalick, Rich. 1995. MacDermid, Inc. Personal communication with Jack Geibig, UT Center
for Clean Products and Clean Technologies. December 8.
Thrasher, Hal. 1995. Shipley Company. Personal communication with Jack Geibig, UT Center
for Clean Products and Clean Technologies. March 2.
Thorn, Ed. 1995a. Electrochemicals, Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. May 16.
Thorn, Ed. 1995b. Electrochemicals, Inc. Personal communication with Jack Geibig, UT
Center for Clean Products and Clean Technologies. December 11.
U.S. Environmental Protection Agency (EPA). 1994. Cleaner Technologies Substitutes
Assessment, Industry: Screen Printing. EPA Office of Pollution Prevention and Toxics,
Washington, D.C. EPA744R-94-005. September.
U.S. Environmental Protection Agency (EPA). 1995. Printed Wiring Board Industry and Use
Cluster Profile. Design for the Environment Program. EPA Office of Pollution
Prevention and Toxics, Washington, D.C. EPA 744-R-95-005.
Wood, Mike. 1995a. MacDermid, Inc. Personal communication with Jack Geibig, UT Center
for Clean Products and Clean Technologies. June 25.
Wood, Mike. 1995b. MacDermid, Inc. Personal communication with Jack Geibig, UT Center
for Clean Products and Clean Technologies. December 7.
2-28
-------
Chapter 3
RISK
This chapter of the Cleaner Technologies Substitutes Assessment (CTSA) addresses the
health and environmental hazards, exposures, and risks that may result from using a making
holes conductive (MHC) technology. The information presented here focuses entirely on MHC
technologies. It does not, nor is it intended to, represent the full range of hazards or risks that
could be associated with printed wiring board (PWB) manufacturing.
Section 3.1 identifies possible sources of environmental releases from MHC
manufacturing and, in some cases, discusses the nature and quantity of those releases. Section
3.2 assesses occupational and general population (i.e., the public living near a PWB facility; fish
in streams that receive wastewater from PWB facilities) exposures to MHC chemicals. This
section quantitatively estimates inhalation and dermal exposure to workers and inhalation
exposure to the public living near a PWB facility. Section 3.3 presents human health hazard and
aquatic toxicity data for MHC chemicals. Section 3.4 characterizes the risks and concerns
associated with the exposures estimated in Section 3.2. In all of these sections, the
methodologies or models used to estimate releases, exposures, or risks are described along with
the associated assumptions and uncertainties. In order to protect the identity of the proprietary
chemicals, the chemical concentrations, exposures, and toxicological data for these chemicals are
not given in the report. However, those proprietary chemicals that may present a potential risk to
human health are identified by their generic chemical name in Section 3.4. Section 3.5
summarizes chemical safety hazards from material safety data sheets (MSDSs) for MHC
chemical products and discusses process safety issues.
3.1 SOURCE RELEASE ASSESSMENT . .
This section of the CTSA uses data from the IPC Workplace Practices Questionnaire,
together with other data sources, to identify sources and amounts of environmental releases.
Both on-site releases (e.g., evaporative or fugitive emissions from the process, etc.) and off-site
transfers (e.g., discharges to publicly-owned treatment works [POTWs]) are identified and, if
sufficient data exist, characterized. The objectives of the Source Release Assessment are to:
• Identify potential sources of releases.
• Characterize the source conditions surrounding the releases, such as a heated bath or the
presence of local ventilation.
• Where possible, characterize the nature and quantity of releases under the source
conditions.
Many of these releases may be mitigated and even prevented through pollution prevention
techniques and good operating procedures at some PWB facilities. However, they are included
in this assessment to illustrate the range of releases that may occur from MHC processes.
3-1
-------
3.1 SOURCE RELEASE ASSESSMENT
A material balance approach was used to identify and characterize environmental releases
associated with day-to-day operation of MHC processes. Modeling of air releases that could not
be explicitly estimated from the data is done in the Exposure Assessment (See Section 3.2).
Section 3.1.1 describes the data sources and assumptions used in the Source Release
Assessment. Section 3.1.2 discusses the material balance approach used and release information
and data pertaining to all MHC process alternatives. Section 3.1.3 presents source and release
information and data for specific MHC process alternatives. Section 3.1.4 discusses
uncertainties in the Source Release Assessment.
3.1.1 Data Sources and Assumptions
This section presents a general discussion of data sources and assumptions for the Source
Release Assessment. More detailed information is presented for specific inputs and releases in
Sections 3.1.2 and 3.1.3.
Sources of data used in the Source Release Assessment include:
• IPC Workplace Practices Questionnaire and Performance Demonstration data (see
Appendix A, Data Collection Sheets).
Supplier-provided data, including publicly-available bath chemistry data and supplier
Product Data Sheets describing how to mix and maintain baths (see Appendix B,
Publicly-Available Bath Chemistry Data).
• Engineering estimates.
The DfE PWB Project publication, Printed Wiring Board Pollution Prevention and
Control: Analysis of Survey Results (EPA., 1995a).
Bath chemistry data were collected in the IPC Workplace Practices Questionnaire, but these data
were not used due to inconsistencies in responses to the questions pertaining to bath chemistry.
Instead, MHC chemical suppliers participating in the Performance Demonstration each submitted
publicly-available data on their respective product lines; estimated bath concentration ranges
were determined based on this information. The use of publicly-available bath chemistry data is
discussed in detail in Section 2.1.4.
Several assumptions or adjustments were made to put the IPC Workplace Practices
Questionnaire data in a consistent form for all MHC technologies. These include the following:
To convert data reported on a per day basis to an annual basis, the number of days per
year reported for questionnaire question 1.1 was used. For data on a weekly or monthly
basis, 12 months per year and 50 weeks per year were assumed.
• If data were reported on a per shift basis, the number of shifts per day (from questionnaire
question 1.4) was used to convert to a per day basis.
• Bath names in the questionnaire database were revised to be consistent with the generic
MHC process descriptions in Section 2.1.3.
To facilitate comparison among process alternatives and to adjust for the wide variations in the
data due to differing size of PWB facilities, questionnaire data are presented here both as
—- —- , , _
-------
3.1 SOURCE RELEASE ASSESSMENT
reported in the questionnaires (usually as an annual quantity consumed or produced), and
normalized by annual surface square feet (ssf) of PWB produced. Normalizing the data,
however, may not fully account for possible differences in processing methods that could result
from higher production levels.
3.1.2 Overall Material Balance for MHC Technologies
A general material balance is presented here to identify and characterize inputs to and
potential releases from the MHC process alternatives. Due to limitations and gaps in the
available data, no attempt is made to perform a quantitative balance of inputs and outputs. This
approach is still useful, however, as an organizing tool for discussing the various inputs to and
outputs from MHC processes and presenting the available data. Figure 3.1 depicts inputs to a
generalized MHC process line, along with possible outputs, including PWB product, solid waste,
air emissions, and wastewater discharges. Many PWB manufacturers have an on-site wastewater
treatment system for pretreating wastewaters prior to direct discharge to a stream or lake or
indirect discharge to a POTW. Figure 3.2 describes a simplified PWB wastewater treatment
system, including the inputs and outputs of interest in the Source Release Assessment.
Inputs
Possible inputs to an MHC process line include bath chemicals, copper-clad PWBs that
have been processed through previous PWB manufacturing process steps, water, and cleaning
chemicals. These inputs are described below.
Ij Bath chemicals used. This includes chemical formulations used for initial bath make-up,
bath additions, and bath replacement. Bath formulations and the chemical constituents of
those formulations were characterized based on publicly-available bath chemistry data
and some proprietary bath chemistry data (see Section 2.1.4 and Appendix B). PWB
manufacturers were asked to report the quantity of MHC chemicals they use annually in
the IPC Workplace Practices Questionnaire, but because the resulting data were of
questionable quality, total chemical usage amounts could not be quantified.
I Copper-clad PWBs. PWBs or inner layers with non-conductive drilled through-holes that
come into the MHC line could add a small amount of copper to the MHC process. Trace
amounts of other additives such as arsenic, chromium, and phosphate may also be
introduced. This applies to all process alternatives where copper is etched off the boards
in the microetch step at the beginning of the MHC process. The amount of copper added
from this process is expected to be small, relative to the other chemical inputs. This
would be, however, the only expected source of copper for the MHC processes where
copper is not otherwise used. This input is not quantified.
I3 Water. Water, usually deionized, is typically used in the MHC process for rinse water,
bath make-up, and equipment cleaning. The water consumption of different MHC
technologies varies according to the number of rinse tanks used in the MHC process.
However, the number of rinse tanks can also vary from facility to facility within a
technology category due to differences in facility operating procedures and water
conservation measures.
! 3-3
-------
3.1 SOURCE RELEASE ASSESSMENT
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3-4
-------
3.1 SOURCE RELEASE ASSESSMENT
Figure 3.2 Wastewater Treatment Process Flow Diagram
,9: ; - ^ > vv - rT w^;-;C- & • ' ,- "'".4. /*. _ «/ -\ / t _
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Water usage data collected in the IPC Workplace Practices Questionnaire includes the
annual amount of water used for bath make-up and rinse water. Annual water usage in
gallons was normalized by dividing the annual water usage in gallons by annual
production in ssf of PWB produced. Both annual and normalized water consumption
data are summarized in Table 3.1.
Based on the normalized data, on average the questionnaire respondents with non-
conveyorizedMHC processes use more than ten times as much water as those with
conveyorized processes. Due to the variability in questionnaire data, the relative rate of
water consumption of the MHC technologies was estimated using both the questionnaire
data and a simulation model of the MHC technologies. This is discussed further in
Section 5.1, Resource Conservation.
I4 Cleaning chemicals. This includes chemicals used for conveyor equipment cleaning,
chemical flush, and other cleaning pertaining to the MHC process line. The amount of
cleaning chemicals used is characterized qualitatively based on IPC Workplace Practices
Questionnaire data and could include chemicals used to clean conveyor equipment
(questionnaire question 3.5) and chemicals used in chemical flush (questionnaire question
4.4). Cleaning chemicals are discussed for specific MHC Technologies in Section 3.1.3.
The total inputs (Itot) = It +12 +13 +14-
3-5
-------
3.1 SOURCE RELEASE ASSESSMENT
Process Type
No. of Responses
Water Usage (I3)
(1,000 gal/year)*
Water Usage
-------
3.1 SOURCE RELEASE ASSESSMENT
baths could also contribute to air releases, but these are expected to be small compared to
volatilization and aerosol losses and are not quantified.
Air releases may be affected by bath temperature, bath mixing methods, and vapor control
methods employed. Questionnaire data for bath agitation and vapor control methods are
summarized below:1
• Most facilities using conveyorized processes use fluid circulation to mix the baths.
The only vapor control method reported is enclosure and venting, which is employed
for all baths on the conveyorized lines. The process baths are completely enclosed and
vented to the outside.
• For facilities using non-conveyorized processes, most use panel agitation and many use
fluid circulation. Air sparging is used primarily in electroless copper and microetch
baths. (More than one method can be used simultaneously.) Vapor control methods
include push-pull for about % of the baths, a bath cover for about 1/4 of the baths, with
enclosure and other methods reported for a few baths.2
Table 3.2 lists average bath surface area, volume, and bath temperature data from the IPC
Workplace Practices Questionnaire. Some of this information (both surface area and
temperature) is used to model air releases in the Exposure Assessment. Surface areas are
calculated from reported bath length and width data. Larger bath surface areas enhance
evaporation. Most baths are maintained at elevated temperatures which also enhances chemical
evaporation.
A2 Evaporation from drying/oven. Air losses due to evaporation from drying steps applies
primarily to carbon and graphite processes with air knife/oven steps. Releases are
discussed qualitatively in Section 3.1.3.
The total outputs to air
= Al + A2.
T&ith
No. of
Responses
Length
(in,)
Width
(in.)
Surface Area
(St-in.)
Volume
(ga**>
Temp
fF)
Electroless Copper, non-convevorized
Accelerator
Acid Dip
Anti-Tarnish
Catalyst
Conditioner/Cleaner
31
12
20
35
35
41
38
43
41
41
23
24
22
23
23
874
795
907
890
882
123
105
109
119
119
81
76
84
98
137
1 From questionnaire question 4.1.
2 Push-pull ventilation combines a lateral slot hood at one end of the tank with a jet of push air from the
opposite end. It is used primarily for large surface area tanks where capture velocities are insufficient to properly
exhaust fumes from the tank.
3-7
-------
3.1 SOURCE RELEASE ASSESSMENT
Bath
Electroless Copper
Microetch
Other
Predip
No. of
Responses
35
35
9
35
Length
On-)
45
41
41
40
Width
-------
3.1 SOURCE RELEASE ASSESSMENT
Bath
Microetch
Other
Post Dip
No. of
Responses
1
1
1
Length
(in.)
15
12
15
Width
Cm.)
63
63
63
Surface Area
(sq. in,)
945
756
945
Volume
(gaL)
206
157
206
Temp
C»)
78
74
Organic-Palladium, conveyorized
Acid Dip
Cleaner
Conditioner
Conductor
Microetch
Other
Post Dip
1
1
1
1
1
1
1
12
24
60
98
25
24
26
49
49
49
49
49
49
49
588
1,176
2,940
4,802
1,225
1,176
1,274
24
37
74
108
37
48
45
79
120
100
115
75
81
77
Tin-Palladium, non-conveyorized
Accelerator
Acid Dip
Anti-Tarnish
Catalyst
Conditioner/Cleaner
Microetch
Other
Predip
10
4
3
11
11
9
4
11
35
29
34
31
34
30
31
31
17*
19
10
16
18
17
18
16
580
532
344
515
576
520
593
497
67
59
51
56
65
64
61
53
134
76
73
111
- 164
76
74
75
Tin-Palladium, conveyorized
Accelerator
Acid Dip
Anti-Tarnish
Catalyst
Conditioner/Cleaner
Microetch
Other
Predip
2
2
1
2
2
2
1
2
40
24
30
86
45
25
30
24
33
33
30
33
33
33
30
33
1,341
780
900
2,742
1,410
810
900
780
80
53
80
173
98
58
80 ,
58
103
94
71
117
114
92
75
81
a Based on IPC Workplace Practices Questionnaire data.
Water Releases. Potential outputs to water include chemical-contaminated wastewater
from rinse tanks, spent bath solutions, and liquid discharges from bath sampling and bail-out.
Chemical-contaminated rinse water is the largest source of wastewater from most MHC process
lines and primarily results from drag-out or drag-in. Drag-out or drag-in is the transfer of
chemicals from one bath to the next by dragging bath solution on a PWB out of one bath and into
the subsequent bath. Drag-in or drag-out losses are estimated to be approximately 95 percent of
uncontrolled bath losses (i.e., losses other than from bath replacement, bail-out, and sampling)
(Bayes, 1996). The quantity of chemicals lost can be reduced through operational practices such
as increased drip time (see Section 6.1, Pollution Prevention). Potential water releases are
discussed further below.
3-9
-------
3.1 SOURCE RELEASE ASSESSMENT
Wj Waste-water. MHC line wastewater primarily consists of chemical-contaminated water
from rinse tanks used to rinse residual chemistry off PWBs between process steps. Water
usage and wastewater composition were addressed by several questions in the IPC
Workplace Practices Questionnaire, with resulting data of variable to poor quality.
Because the volume of rinse water used in MHC processes is much greater than water
used in all other applications, the quantity of wastewater generated is assumed to be equal
to water usage (I3). The previous discussion of water usage data also applies to
wastewater amounts.
W2 Spent bath solution. Bath concentrations vary over time (as the bath ages) and as PWBs
are processed through the baths. Spent bath solutions are chemical bath solutions that
have become too contaminated or depleted to properly perform a desired function. Spent
bath solutions are removed from a process bath when a chemical bath is replaced.
As noted above, bath formulations and chemical constituents of those formulations were
characterized based on publicly-available bath chemistry data and some proprietary bath.
chemistry data (see Section 2.1.4 and Appendix B). For the purposes of this assessment,
chemical concentrations within the spent baths were assumed to be the same as bath
make-up concentrations. The amount of spent bath disposed was addressed in the IPC
Workplace Practices Questionnaire question 4.3, Chemical Bath Replacement, but many
respondents did not have this information. Therefore, total chemical disposal amounts
have not been quantified. Table 3.3 presents a summary of spent bath treatment methods
reported in the questionnaire by MHC technology.
W3 Bath sampling and bail-out. This includes bath solutions disposed of after sampling and
analysis and bath bail-out (sometimes done prior to bath additions). In some cases
sampling may be performed at the same time as bail-out if the process bath is on a
controller.
Routine bail-out activities could result in a large amount of bath disposal. Because this
activity was not included in the IPC Workplace Practices Questionnaire there is only
limited information on frequency or amount of bail-out expected. Chemical loss due to
bath sampling was assumed to be negligible.
The total outputs to water (Wtot) = W! + W2 + W3.
Wastewater Treatment. Figure 3.2 showed the overall water and wastewater treatment
flows, including chemical bath solutions and wastewater inputs to treatment, any pre-treatment or
treatment performed on-site or off-site, sludge generated from either on-site or off-site treatment,
and final effluent discharge to surface water. PWB manufacturers typically combine wastewater
effluent from other PWB manufacturing processes prior to on-site wastewater pretreatment. The
pretreated wastewater is then discharged to a POTW.
3-10
-------
3.1 SOURCE RELEASE ASSESSMENT
«
ON
CS
s
as
o
13
•e
1
1
o
03
P
ilities u;
CS
a
H
o
o
o
o
3
cx
e
I
e
4)
a
cc
00
00
u
en
cs
CS
,0
of
per,
orized
Copp
pper,
Electrole
oles
ey
Carbon,
convey
ve Po
zed
Co
con
phite,
conveyorized
ldehyde
Copper,
diu
zed
ey
F
ole
onv
Gra
Non
Elec
P
Org
c-Palladi
Tk-Pall
3-11
-------
3.1 SOURCE RELEASE ASSESSMENT
Table 3.4 summarizes treatment and discharge methods and copper concentrations in
PWB plant discharges reported in Pollution Prevention and Control: Analysis of Survey Results
(EPA, 1995a). The primary purpose of most PWB manufacturer's wastewater treatment systems
is the removal of dissolved metals. This is accomplished with conventional metals precipitation
systems (a series of unit operations using hydroxide precipitation followed by separation of the
precipitated metals), ion exchange-based metals removal systems, and combined
precipitation/ion exchange systems. The most common type is conventional metals precipitation,
which includes precipitation units followed by either clarifiers or membrane filters for solids
separation. The use of clarifiers is the predominant method for separation of precipitated solids
from the wastewater. Wastewater treatment systems are discussed further in Section 6.2,
Recycle, Recovery, and Control Technologies Assessment.
Table 3.4 Treatment and Discharge Methods and Copper Concentration Summarized
from Pollution Prevention and Control Survey
Respondent
Identification No.
By MHC
Technology
Copper Discharge
Limitations
Max
(mg/1)
Avg
(mg/1)
Wastewater
Copper
Concentration
(Wg/l)
Discharge
Type of Wastewater
Treatment
Electroless Copper
31838
36930
44486
955703
36930
237900
502100
358000
959951
t3
44657
55595
3023
42692
6710
41739
955099
t2
947745
42751
3
4.34
4.5
3
2.59
2.7
1
2
3.22
2.7
3
NR
1.5
4.5
4.5
4
1.5
2.2
3.38
3
1.5
2.6
2.7
2.07
1.59
1
1.5
1.5
0.45
2.7
2.07
NR
none
2.7
0.37
0.4
none
2.07
2.07
2.07
NR
NR
NR
0.4
1
1.2
2
2
5
5
7
10
12.5
17.5
20
25
30
30
30
33
indirect
indirect
indirect
indirect
indirect
indirect
indirect
indirect
indirect
indirect
indirect
direct
indirect
direct
indirect
direct
indirect
indirect
indirect
indirect
precipitation
electrowinning/ion exchange
ion exchange
precipitation/clarifier
ion exchange
precipitation/membrane
precipitation/clarifier
precipitation/filter press
ion exchange, precipitation/
membrane, resist strip
ion exchange
precipitation/clarifier
precipitation/membrane
precipitation/clarifier
precipitation/clarifier, sludge
dryer, air scrubber
precipitation/clarifier
precipitation/clarifier, polishing
filter, filter press
3-12
-------
3.1 SOURCE RELEASE ASSESSMENT
Respondent
Identification No.
ByMHC
Technology
tl
946587
25503
965874
273701
953880
133000
32482
107300
33089
3470
Copper Discharge
Limitations
Max
(mg/1)
1
3.4
3 .
3.38
3.38
0.25
1.5
3.38
2
3.38
1.5
AYg
(mg/1)
0.03
none
2.07
2.07
2.07
none
none
2.07
1
2.07
2.07
Wastewater
Copper
Concentration
(tog/1)
35
40
40
40
50
57
60
65
80
300
Discharge
direct
indirect
indirect
indirect
indirect
indirect
indirect
indirect
direct
indirect
indirect
Type of Wastewater
Treatment
precipitation/clarifier, sludge
dryer, chemical tester
precipitation/clarifier
ion exchange
ion exchange/electrowinning
ion exchange, electrowinning
precipitation/clarifier, sludge
dryer
precipitation/clarifier
precipitation/clarifier, sludge
dryer, equalization
precip/clarifier, filter press
ion exchange
Graphite
43841
4.3
2.6
200
indirect
precipitation/filtration, filter
press, equalization, etc.
Palladium
279
37817a
29710
43694
Average
Median
Max
Min
Standard Deviation
3
4.5
0.49
'3
2.75
3
4.50
0.25
1.20
2.02
3.5
0.41
2.07
1.50
2.07
3.50
0.03
0.97
NR
3
4
30
35.7rO
30
300.00
0.2
57.54
direct
indirect
direct
indirect
ion exchange, electrowinning
ion exchange
ion exchange
Respondent 37817 reported Cu max = 5.0 mg/1; assumed 4.5 mg/1 in compliance with Federal regulations.
NR: Not Reported.
Source: EPA, 1995a.
Following any in-house wastewater treatment, facilities release wastewater either directly
to surface water or indirectly to a POTW. Sludge from on-site wastewater treatment is discussed
in the section below (Solid Waste). The data for discharge type (direct or indirect) are discussed
for specific processes in Section 3.1.3.
, Permit data for releases were not collected; this was deleted from the questionnaire upon
request by industry participants. However, PWB manufacturers who responded to the IPC
3-13
-------
3.1 SOURCE RELEASE ASSESSMENT
Workplace Practices Questionnaire were asked to provide the maximum and average metals
concentrations (e.g., copper, palladium, tin) in wastewater from their MHC line (questionnaire
question 2.3, Wastewater Characterization). Several respondents indicated the question could
not be answered, did not respond to this question, or listed their POTW permit discharge limits.
This is because there are many sources of metals, especially copper, in PWB manufacturing.
PWB manufacturers typically combine effluents from different process steps prior to wastewater
treatment. Thus, the chemical constituents and concentration in wastewater could not be
characterized.
Solid Waste. Solid wastes are generated by day-to-day MHC line operation and by
wastewater treatment of MHC line effluents. Some of these solid wastes are recycled, while
others are sent to incineration or land disposal. Solid waste outputs include:
S, Solid waste. Solid wastes could include spent bath filters, chemical precipitates (e.g.,
CuSO4 crystals from etch bath), packaging or chemical container residues, and other solid
waste from the process line, such as off-specification PWBs. Chemical baths are
typically replaced before precipitation occurs. However, if precipitation does occur, some
precipitates, such as copper sulfate crystals, may be recycled. Container residue is
estimated by EPA to be up to four percent of the chemicals use volume (Froiman, 1996).
An industry reviewer indicated this estimate would only occur with very poor
housekeeping practices and is not representative of the PWB industry (Di Margo, 1996).'
The questionnaire data did not include chemical characterization of solid wastes.
S2 Drummed solid or liquid -waste. This includes other liquid or solid wastes that are
drummed for on-site or off-site recycling or disposal. Some spent baths and wastes can
be recycled or recharged, such as etchant. No data were available to characterize these
wastes.
S3 Sludge from on-site wastewater treatment. Questionnaire respondents were asked to
report the amount of sludge they generated during on-site wastewater treatment that could
be attributed to MHC line effluents (questionnaire question 2.4, Wastewater Discharge
and Sludge Data). Both annual quantities and data normalized to pounds of sludge per ssf
of PWB produced are presented hi Table 3.5. However, many PWB manufacturers have
indicated that the amount of sludge from the MHC process cannot be reliably estimated
since effluents from various PWB manufacturing process steps are combined prior to
wastewater treatment. In addition, the amount of sludge generated during wastewater
treatment varies according to the MHC technology used, the treatment method used,
facility operating procedures, the efficiency with which bath chemicals and rinse water
are used, and other factors. Thus, the comparative amount of sludge generated due to the
choice of an MHC technology could not be determined, nor were data available to
characterize the concentrations of metals contributed by the MHC line.
The total solid waste output (Stot) = Sl + S2 + S3.
3-14
-------
3.1 SOURCE RELEASE ASSESSMENT
Table 3.5 Sludge Generation from Wastewater Treatment of MHC Line Effluents
Process Type
No. of Responses
Sl«dge(S4)
(Ibs/year)*
Sludge (S4)
(lbs/1,000 ssf>*
Electroless Copper
Non-conveyorized
Conveyorized
35
1
600 - 100,000 (25,000)
1,000
2-530 (96)
0.31
Carbon
Conveyorized
2
no data
no data
Conductive Polymer
Conveyorized
0
no data
no data
Graphite
Conveyorized
4
5.5 - 920 (380)
0.01 - 5.6 (2.2)
Non-Formaldehyde Electroless Copper
Non-conveyorized
1
200
3.7
Organic-Palladium
Non-conveyorized
Conveyorized
1
1
5,000
21,600
190
45
Tin-Palladium
Non-conveyorized
Conveyorized
11
2
200 - 24,000 (6,700)
17,000
1.3-94(27)
9.5
All Processes
Non-conveyorized
Conveyorized
48
10
200 - 100,000 19,500)
5.5 - 21,600 (6,800)
1.3-530(79)
0.01-45(10)
Range and average values for each from questionnaire data.
Transformations. Transformations within the MHC system boundary could include:
R! Chemical reaction gains or losses. This includes any chemical species consumed,
transformed, or produced in chemical reactions and side reactions occurring in the
process baths. Reactions and side reactions within the baths could result in either
chemical losses or production of new chemicals as degradation products. One important
set of reactions involve formaldehyde in the electroless copper process. Formaldehyde,
which is utilized as a reducing agent, is converted to formic acid. In a secondary or side
reaction formaldehyde also breaks down into methanol and the formate ion. This reaction
is the only source of formate ion in the electroless copper bath. Other side reaction
products include BCME (bis-chloromethyl ether) which is produced in a reaction between
hydrochloric acid and formaldehyde (Di Margo, 1996).
The overall material balance: Itot = A^ + Wtot + Stot + Pt ± R,.
3-15
-------
3.1 SOURCE RELEASE ASSESSMENT
3.1.3 Source and Release Information For Specific MHC Technology Categories
This section describes the specific inputs and outputs in the material balance for each
MHC technology. To facilitate comparison among process alternatives, and to adjust for the
wide variations in the data due to differing sizes of PWB facilities, data are presented both as
reported in the IPC Workplace Practices Questionnaire, and normalized by production amounts
(annual ssf of PWB produced). Average values from the IPC Workplace Practices Questionnaire
database are reported here for summary purposes.
Electroless Copper Process
Figure 3.3 illustrates the generic electroless copper process steps and typical bath
sequence evaluated in the CTSA. The process baths depicted in Figure 3.3 represent an
integration of the various products offered within the electroless copper technology category.
The number and location of rinse steps shown in the figure are based on the IPC Workplace
Practices Questionnaire data. Figure 3.3 lists the types and sequence of baths in a generic
electroless copper line, but the types and sequence of baths in an actual line could vary.
Water Usage (I3) and Wastewater (Wi). Water usage data from the IPC Workplace Practices
Questionnaire were presented in Table 3.1; the amount of wastewater generated is assumed equal
to the amount of water used. Of respondents using an electroless copper process, 1 1 discharge
wastewater directly to a stream or river following the appropriate treatment while 20 facilities use
indirect discharge (e.g., to a POTW). (Five facilities did not respond to the question.) While
several facilities using electroless copper completed the questionnaire, only a single facility used
the conveyorized process. This large facility produces over three million ssf of PWB per year. In
summary:
• Reported water usage for the facility using a conveyorized electroless copper process is
3.3 million gallons per year, or about one gallon per ssf of PWB produced.
• Reported water usage for the facilities using non-conveyorized processes average 4.0
million gallons per year, or 18 gallons per ssf of PWB produced.
Chemical constituents and concentrations in wastewater could not be adequately characterized.
Cleaning Chemicals (I4). Chemicals used for cleaning of electroless copper equipment,
as reported in the IPC Workplace Practices Questionnaire, include water, sodium persulfate,
sulfuric acid, hydrogen peroxide, nitric acid, and "21 1 solvent."
Bath Chemicals Used (It). Appendix B presents estimated bath chemical concentrations
for the electroless copper process. The amount of bath chemicals used could not be quantified
from questionnaire data.
Spent Bath Solutions (W2). The quantity of spent bath solution could not be determined
from the data. Spent bath treatment methods were presented in Table 3.3. Precipitation
pretreatment and on-site recycling are reported treatment methods for the conveyorized
electroless copper process; precipitation pretreatment and pH neutralization were most
commonly reported as methods for the non-conveyorized electroless copper process.
3A6
-------
3.1 SOURCE RELEASE ASSESSMENT
Figure 3.3 Generic Electroless Copper Process Steps, and Typical Bath Sequence
' , , 'If- - . }- ^__-* "
"."* "
' * 'i "
'"' ' " di?
^ . ''
^ 1^ " *^*>
* -
J*
" >. ' ''
'-'f '".'i'
^^ f^ *
^/ _ .. - f
^ t^^~* <' >*~ *
* ~ > ', *
r, "\ " ,::
/" ,
•% " -> fJ * „
• .-" .^' „ "~,
- " ^ ^-" . >/
f " '
* _ ''''
1 Cleaner/Conditioner
JT' H/ x "^'i
2 Water Rinse x 2
.,,£""5 ''V ^ * *" w
" V «c$^
3 Microetch
~~' " l:^-:---
4 Water Rinse x 2
v x •> 1 5
;«"»- W ,-•''" V?
5 Predip
-r"
1^ "^ " ^
*^^^^ \ ^ ~'
"* " ' Jj~
-"•*" -—
Ij , ^ '
J ?/ ..- '-*•
1 ' ;"J? f - - -t -
1* ' 7i-
*^f" t~ , "• Iff <
?"l"'1
x\ "' 5^' <^
', ^ „__ ,, <<_
1' v-^* ™. ' *>? ~
," r^ 'Y J
1, - .-,-/ ,- - - ,
/.- "" .-.
^0 ^;1;,^ ^/T^'xys/ ^/ Af,
6 Catalyst
Xft"^' -^" -?"'"
7 Water Rinse x 2
~" ^ ;' ^^::
* Accelerator
y ,. ;-V-'"l'"^.
» Water Rinse
1- - 4< ; - y
~ , ^ ..
* / >f-^
^ *\ u, "^ *~ >t ^ '
;tX
• •> ~ ^ ^ ^
I^> " - •" „ -
t -J^f^
;"' ;"XV ^X^,^r .--V"' '..,
10 Electroless Copper
-_--;> ,/^vV-' ;.
11 Water Rinse x 2
*** i
12 Acid Dip
^"*X^. , -f ^"?
13 Water Rinse
1) * kit '
»/•• ^ , 'V* , "
2jc ^^y:
*~ // ,-? •*•*• ^
*&- " , ,r"-J - v
I"> " * " ,^
- ^"^
1 ... ,t ;~ sr
< r \ ^-^\ , "^ ^ • - ^ :> _.^ , 2' <-
14 Anti-Tarnish \ /" ,^
s »*'"?x .'HJr :^v- , f::"' .>r ^ * ^
15 Water Rinse 1 " - /f
.»-. " - ^' "
-. -t ^ *>A
3-17
-------
3.1 SOURCE RELEASE ASSESSMENT
Evaporation From Baths (Aj). Air releases are modeled in the Exposure Assessment
(Section 3.2). To summarize questionnaire data:
• For the single conveyorized electroless copper process, fluid circulation is used in all but
the microetch bath. Enclosure is used for vapor control for all baths.
• For non-conveyorized electroless copper facilities, panel agitation is used in most baths,
fluid circulation in about 1/3 of the baths, air sparging is primarily used in electroless
copper and a few microetch baths, and a few baths use other mixing methods. Vapor
control methods include push-pull for about 1A of the baths, a bath cover for about 1/4 of
the baths, with enclosure and other methods reported for a few of the baths.
• Table 3.2 lists bath surface area, volume, and bath temperature data from the IPC
Workplace Practices Questionnaire.
Evaporation From Drying/Oven (A2). This source of air emissions does not apply to
electroless copper processes since oven drying is not required and air drying immediately follows
water rinsing.
Chemicals Incorporated Onto PWBs (P,). Copper is added to the boards in the
electroless copper process. Small quantities of palladium from the catalyst are also deposited on
the PWBs.
Drummed Solid or Liquid Waste (S2). This was reported as a spent bath treatment
method for either solution or sludge for 16 out of 240 baths by the non-conveyorized electroless
copper facilities (see Table 3.3). The total quantity of drummed waste was not reported.
Sludge Amounts From On-Site Treatment (S3). Sludge generation data are presented
in Table 3.5. In general:
• Reported sludge amounts for the facility using a conveyorized process are 1,000 Ibs/year,
or 0.31 Ibs per 1,000 ssf of PWB produced.
• Reported sludge amounts for the facilities using non-conveyorized processes average
25,000 Ibs/year, or 96 Ibs per 1,000 ssf of PWB produced.
Metal concentrations in sludge could not be adequately characterized.
Chemical Reaction Gains or Losses (Ri). The most well-documented chemical
reactions in electroless copper baths involve formaldehyde. Formaldehyde is used as a copper
reducing agent, and in this reaction formaldehyde is converted to formic acid and hydrogen gas.
In a secondary (unwanted) reaction called the Cannizzaro reaction, formaldehyde breaks down to
methanol and the formate ion which in a caustic solution forms sodium formate. A study by
Merix Corporation found that for every one mole of formaldehyde reacting in the intended
copper deposition process, approximately one mole was reacting with hydroxide in the
Cannizzaro reaction. Other studies have found that the side reaction tendency goes up with the
alkalinity of the process bath (Williamson, 1996). A search of literature references failed to
produce sufficient quantifiable data to characterize these reactions.
3-18
-------
3.1 SOURCE RELEASE ASSESSMENT
Carbon Process
Figure 3.4 illustrates the carbon process steps and bath sequence evaluated in the CTSA.
The number and location of rinse steps shown in the figure are based on IPC Workplace
Practices Questionnaire data. Thus, Figure 3.4 lists the types and sequence of baths in a generic
carbon line, but the types and sequence of baths in an actual line could vary. Both carbon
facilities hi the IPC Workplace Practices Questionnaire database use conveyorized equipment.
Figure 3.4 Generic Carbon Process Steps and Typical Bath Sequence
Cleaner
Water Rinse
Carbon Black
4
Air Knife/Dry 1
Water Rinse
6
Conditioner
1
Water Rinse
J
8 Carbon Black I
Air Knife/Dry
10
Microetch
11 Water Rinse
Water Usage (I3) and Wastewater (Wj). Water usage data were summarized in Table
3.1; wastewater generation is assumed equal to water usage. Reported water usage for the two
facilities is 330,000 gallons per year, or 0.28 gallon per ssf of PWB produced. Both carbon
facilities use indirect discharge of wastewater. Chemical constituents and concentrations in
wastewater could not be adequately characterized.
3-19
-------
3.1 SOURCE RELEASE ASSESSMENT
Cleaning Chemicals (I4). Only water is used for equipment cleaning, as reported in the
IPC Workplace Practices Questionnaire.
Bath Chemicals Used (Ij). Appendix B presents estimated bath chemical concentrations
for the carbon process. The amount of bath chemicals used could not be quantified from the
data.
Spent Bath Solutions (W2). The quantity of spent bath solution could not be determined
from available data. Spent bath treatment methods were presented in Table 3.3. Precipitation
pretreatment and pH neutralization are reported methods for carbon processes.
Evaporation From Baths (Aj). Air releases are modeled in the Exposure Assessment
(Section 3.2). For both facilities using conveyorized carbon, fluid circulation is used for bath
agitation and enclosure is used for vapor control for all baths. Table 3.2 lists bath surface area,
volume, and bath temperature data.
Evaporation From Drying/Oven (A2). Air knife/oven drying occurs after the carbon
black and fixer steps. Any solution adhering to the boards would be either blown off the boards
and returned to the sump, or volatilized in the oven. Air emissions from air knife/oven drying
were not modeled.
Chemicals Incorporated Onto PWBs (Px). Carbon black is added to the boards in this
process.
Drummed Solid or Liquid Waste (S2). This was not reported as a spent bath treatment
method for carbon processes (see Table 3.3).
Sludge Amounts From On-Site Treatment (S3). Sludge data were not reported for the
carbon processes.
Conductive Ink Process
A generic conductive ink sequence is shown in Figure 3.5. Source release data for
conductive ink are not available since there are no facilities currently using the process for the
production of multi-layer PWBs.
3-20
-------
3.1 SOURCE RELEASE ASSESSMENT
Figure 3.5 Generic Conductive Ink Process Steps
Microetch
2 Water Rinse
3 Air Knife Dry |
r~ "t ' 1
^ ^ ^.r-<
*^ ,-f fT^ «wv -
_^ f
4 Screen Creation
J
5 Screen Print Ink
(Sidel) |
Dry Ink
7 Screen Print Ink
(Side 2) I
Ink Curing
Overcoat (Side 1)
10
Oven Dry
tAO- 11
Overcoat (Side 2)
«,'•
12 Oven Dry
-«
if «!&& \>s£
Conductive Polvmer Process
Figure 3.6 illustrates the generic conductive polymer process steps and typical bath
sequence evaluated in the CTSA. The number and location of rinse steps shown in the figure are
based on IPC Workplace Practices Questionnaire data. Thus, Figure 3.6 lists the types and
sequence of baths in a generic conductive polymer line, but the types and sequence of baths in an
actual line could vary. The single conductive polymer facility in the IPC Workplace Practices
Questionnaire data uses conveyorized equipment.
Water Usage (I3) and Wastewater (Wj). The single facility using a conductive polymer
process uses indirect discharge of wastewater.
3-21
-------
3.1 SOURCE RELEASE ASSESSMENT
Figure 3.6 Generic Conductive Polymer Process Steps and Typical Bath Sequence
10
Micro etch
±
2 Water Rinse x 3
3 Cleaner/Conditioner
4 Water Rinse x 3
Catalyst
I6 Water Rinse x 2
Conductive Polymer
8 Water Rinse x 2
Microetch
Copper Flash
Cleaning Chemicals (I4). Only water is used for equipment cleaning, as reported in the
IPC Workplace Practices Questionnaire data.
Bath Chemicals Used (Ij). Appendix B presents estimated bath chemical concentrations
for the conductive polymer process. The amount of bath chemicals used could not be quantified
from the data.
Spent Bath Solutions (W2). The quantity of spent bath solution could not be determined
from the data. Spent bath treatment methods are presented in Table 3.3. pH neutralization is
reported as a treatment method for the conductive polymer process.
Evaporation From Baths (Aj). Air releases are modeled in the Exposure Assessment
(Section 3.2). The facility using a conveyorized conductive polymer process reported using fluid
circulation for all baths and enclosure for vapor control for all baths. Table 3.2 shows bath
surface area, volume, and bath temperature data.
3-22
-------
3.1 SOURCE RELEASE ASSESSMENT
Evaporation From Drying/Oven (A2). This source of air emissions does not apply to
the conductive polymer process since oven drying is not required and air drying immediately
follows water rinsing.
Chemicals Incorporated Onto PWBs (Pj). A polymer is added to the boards in this
process.
Drummed Solid or Liquid Waste (S2). This was not reported as a spent bath treatment
method for the conductive polymer process (see Table 3.3).
Sludge Amounts From On-Site Treatment (S3). Sludge amounts were not reported for
this process.
Graphite Process
Figure 3.7 illustrates the generic graphite process steps and typical bath sequence
evaluated in the CTSA. The process baths depicted in Figure 3.7 represent an integration of the
various products offered within the graphite technology category. The number and location of
rinse steps shown in the figure are based on the IPC Workplace Practices Questionnaire data.
Thus, Figure 3.7 lists the types and sequence of baths hi a generic graphite line, but the types and
sequence of baths in an actual line could vary. The four facilities in the IPC Workplace Practices
Questionnaire database use conveyorized equipment.
Figure 3.7 Generic Graphite Process Steps and Typical Bath Sequence
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3-23
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3.1 SOURCE RELEASE ASSESSMENT
Water Usage (I3) and Wastewater (Wj). Water usage data are presented in Table 3.1.
For graphite, two facilities use direct and two facilities use indirect discharge. Reported water
usage for the facilities using a conveyorized process averages 914,000 gallons per year, or 2.2
gallons per ssf of PWB produced.
Cleaning Chemicals (I4). Chemicals used for equipment cleaning, as reported in the IPC
Workplace Practices Questionnaire, include water and ammonia.
Bath Chemicals Used (T^). Appendix B presents estimated bath chemical concentrations
for the graphite process. The amount of chemicals used could not be determined from the data.
Spent Bath Solutions (W2). Spent bath treatment methods are presented in Table 3.3.
Precipitation pretreatment, pH neutralization, and discharge to a POTW are reported methods for
the graphite process.
Evaporation From Baths (Aj). Air releases are modeled in the Exposure Assessment
(Section 3.2). To summarize Workplace Practices data:
• For facilities using a conveyorized graphite process, fluid circulation is used in most
baths. Enclosure for vapor control is employed for all of the baths.
• Table 3.2 lists bath surface area, volume, and bath temperature data from the IPC
Workplace Practices Questionnaire.
Evaporation From Drying/Oven (A2). Air knife/oven drying occurs after the graphite
and fixer steps. Any solution adhering to the boards would be either blown off the boards and
returned to the sump, or volatilized in the oven. Air emissions from air knife/oven drying were
not modeled.
Chemicals Incorporated Onto PWBs (P,). Graphite is added to the boards in this
process.
Drummed Solid or Liquid Waste (S2). This was reported as a spent bath treatment
method for two out of 13 baths by the facilities using a conveyorized graphite process (see Table
3.3).
Sludge Amounts From On-Site Treatment (S3). Sludge generation data are presented
in Table 3.5. Reported sludge amounts for the facilities using a conveyorized process average
380 Ibs/year, or 2.2 Ibs per 1,000 ssf of PWB produced.
Non-Formaldehyde Electroless Copper Process
Figure 3.8 illustrates the generic non-formaldehyde electroless copper process steps and
typical bath sequence evaluated in the CTSA. The number and location of rinse steps shown in
the figure are based on IPC Workplace Practices Questionnaire data. Thus, Figure 3.8 lists the
types and sequence of baths in a generic non-formaldehyde electroless copper line, but the types
and sequence of baths in an actual line could vary. The single non-formaldehyde electroless
3-24
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3.1 SOURCE RELEASE ASSESSMENT
copper facility in the IPC Workplace Practices Questionnaire database uses a non-conveyorized
equipment configuration. This is a small facility that produces just over 50,000 ssf of PWB per
year.
Figure 3.8 Generic Non-Formaldehyde Electroless Copper Process Steps
and Typical Bath Sequence
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Water Usage (I3) and Wastewater (Wj). Water usage data for the single non-
formaldehyde electroless copper facility in the IPC Workplace Practices Questionnaire database
were presented in Table 3.1; wastewater generation is assumed equal to water usage. The non-
formaldehyde electroless copper facility indicated it discharges wastewater directly to a receiving
3-25
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3.1 SOURCE RELEASE ASSESSMENT
stream, rather than a POTW. Chemical constituents and concentrations in wastewater could not
be adequately characterized.
Cleaning Chemicals (I4). Only water is used for equipment cleaning, as reported in the
IPC Workplace Practices Questionnaire.
Bath Chemicals Used (It). Appendix B presents estimated bath chemical concentrations
for the non-formaldehyde electroless copper process. The amount of bath chemicals used could
not be quantified from data.
Spent Bath Solutions (W2). The quantity of spent bath solutions could not be
determined from available data. Spent bath treatment methods are presented in Table 3.3. No
treatment methods were reported for the non-formaldehyde electroless copper process.
Evaporation From Baths (A^. Air releases are modeled in the Exposure Assessment
(Section 3.2). The non-formaldehyde electroless copper facility uses panel agitation in all baths
and fluid circulation in most baths. The only vapor control method reported is the use of a
removable bath cover for the microetch bath. Table 3.2 lists bath surface area, volume, and bam
temperature data from the IPC Workplace Practices Questionnaire.
Evaporation From Drying/Oven (A2). This source of air emissions does not apply to
non-formaldehyde electroless copper processes since oven drying is not required and air drying
immediately follows water rinsing.
Chemicals Incorporated Onto PWBs (Pi). Copper is added to the boards in the non-
formaldehyde electroless copper process.
Drummed Solid or Liquid Waste (S2). This was not reported as a spent bath treatment
method for the non-formaldehyde copper facility (see Table 3.3).
Sludge Amounts From On-Site Treatment (S3). These data are presented in Table 3.5.
Reported sludge amounts for the non-formaldehyde electroless copper facility are 200 Ibs/year,
or 3.7 Ibs per 1,000 ssf of PWB produced. Metal concentrations in sludge were not
characterized.
Organic-Palladium Process
Figure 3.9 illustrates the generic organic-palladium process steps and bath sequence
evaluated in the CTSA. The number and location of rinse steps shown in the figure are based on
IPC Workplace Practices Questionnaire data. Thus, Figure 3.9 lists the types and sequence of
baths in a generic organic-palladium line, but the types and sequence of baths in an actual line
could vary. One organic-palladium facility in the IPC Workplace Practices Questionnaire
database uses conveyorized equipment; the other uses non-conveyorized equipment.
3-26
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3.1 SOURCE RELEASE ASSESSMENT
Figure 3.9 Generic Organic-Palladium Process Steps and Typical Bath Sequence
Cleaner
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Water Rinse
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Water Usage (I3) and Wastewater (Wt). Water usage data from the questionnaire were
presented in Table 3.1; wastewater generation is assumed equal to water usage. Of the two
respondents using organic-palladium, one discharges directly to a stream or river following the
appropriate treatment and one discharges to a POTW. In summary:
• Reported water usage for the facility using a conveyorized process is 881,000 gallons per
year, or 1.8 gallons per ssf of PWB produced.
• Reported water usage for the facility using a non-conveyorized process is 7.7 million
gallons per year, or 300 gallons per ssf of PWB produced.
3-27
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3.1 SOURCE RELEASE ASSESSMENT
Cleaning Chemicals (I4). Chemicals used for equipment cleaning, as reported in the IPC
Workplace Practices Questionnaire, include water, nitric acid, hydrogen peroxide, sulfuric acid,
and iron chloride.
Bath Chemicals Used (Ij). Appendix B presents estimated bath chemical concentrations
for the organic-palladium process. The amount of bath chemicals used could not be quantified
from the data.
Spent Bath Solutions (W2). The quantity of spent bath solution could not be determined
from the data. Spent bath treatment methods are presented in Table 3.3. Precipitation
pretreatment was reported for conveyorized organic-palladium and pH neutralization for non-
conveyorized organic-palladium processes.
Evaporation From Baths (Aj). Air releases are modeled in the Exposure Assessment
(Section 3.2). To summarize the data:
• For the organic-palladium facility using a conveyorized process, fluid circulation is
reported for most of the baths and enclosure is used for vapor control for all baths.
• For the organic-palladium facility using a non-conveyorized process, panel agitation and
fluid circulation are reported for most batiis. Push-pull is used as a vapor control method
for most baths.
• Table 3.2 lists bath surface area, volume, and bath temperature data.
Evaporation From Drying/Oven (A2). This source of air emissions does not apply to
the organic-palladium process since oven drying is not required and air drying immediately
follows water rinsing.
Chemicals Incorporated Onto PWBs (Pj). Palladium is added to the board in this
process.
Drummed Solid or Liquid Waste (S2). This was not reported as a spent bath treatment
method for organic-palladium processes (see Table 3.3).
Sludge Amounts From On-Site Treatment (S3). These data are presented in Table 3.5.
In summary:
• Reported sludge amounts for the facility using a conveyorized process were 21,600
Ibs/year, or 45 Ibs per 1,000 ssf of PWB produced.
* Reported sludge amounts for the facility using a non-conveyorized process were 5,000
Ibs/year, or 190 Ibs per 1,000 ssf of PWB produced.
Metal concentrations in sludge could not be adequately characterized.
3-28
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3.1 SOURCE RELEASE ASSESSMENT
Tin-Palladium Process
Figure 3.10 illustrates the generic tin-palladium process steps and bath sequence
evaluated in the CTSA. The process baths depicted in Figure 3.10 represent an integration of the
various products offered within the tin-palladium technology category. The number and location
of rinse steps shown in the figure are based on IPC Workplace Practices Questionnaire data.
Thus, Figure 3.10 lists the types and sequence of baths in a generic tin-palladium line, but the
types and sequence of baths in an actual line could vary. Thirteen tin-palladium facilities are in
the IPC Workplace Practices'Questionnaire database. Of these, two use convey orized equipment
and 11 use non-conveyorized.
Figure 3.10 Generic Tin-Palladium Process Steps and Typical Bath Sequence
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Water Usage (I3) and Wastewater (W,). Water usage data from the IPC Workplace
Practices Questionnaire were presented in Table 3.1; wastewater generation is assumed equal to
water usage. Of respondents using tin-palladium, two discharge wastewater directly to a stream
or river following the appropriate treatment while ten facilities use indirect discharge (e.g., to a
POTW). (One facility did not respond to the question.) In summary:
3-29
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3.1 SOURCE RELEASE ASSESSMENT
• Reported water usage for the facilities using conveyorized processes average 912,000
gallons per year, or 0.58 gallons per ssf of PWB produced.
• Reported water usage for the facilities using non-conveyorized processes average 1.6
million gallons per year, or 7.1 gallons per ssf of PWB produced.
Cleaning Chemicals (I4). Chemicals used for equipment cleaning, as reported in the IPC
Workplace Practices Questionnaire, include water, sodium hydroxide, hydrochloric acid, and
nitric acid.
Bath Chemicals Used (Ij). Appendix B presents estimated bath chemical concentrations
for the tin-palladium process. The amount of bath chemicals used could not be quantified from
the data.
Spent Bath Solutions (W2). The quantity of spent bath solution could not be determined
from the data. Spent bath treatment methods are presented in Table 3.3. Precipitation
pretreatment and pH neutralization are the only reported methods for the conveyorized process
and are the most commonly reported methods for the non-conveyorized tin-palladium process.
Evaporation From Baths (A^. Air releases are modeled in the Exposure Assessment
(Section 3.2). To summarize questionnaire data:
• For the conveyorized tin-palladium process, fluid circulation is reported as a mixing
method for all of the baths and enclosure is used for vapor control for all baths.
• For the non-conveyorized tin-palladium processes, panel agitation is used in about 2/3 of
the baths, fluid circulation in about 1A of the baths, and air sparging for 1/3 of the
microetch baths. Vapor control methods include push-pull and enclosure for a few baths,
and covering for about 1/3 of the baths.
• Table 3.2 lists bath surface area, volume, and bath temperature data.
Evaporation From Drying/Oven (A2). This source of air emissions does not apply to
tin-palladium processes since oven drying is not required and air drying immediately follows
water rinsing.
Chemicals Incorporated Onto PWBs (Pt). Palladium and small quantities of tin are
added to the board in the tin-palladium process.
Drummed Solid or Liquid Waste (S2). This was reported as a spent bath treatment
method for six out of 64 baths by the facilities with non-conveyorized tin-palladium processes
(see Table 3.3). The total quantity of drummed waste was not reported.
Sludge Amounts From On-Site Treatment (S3). Sludge data are presented in Table 3.5.
In general:
• Reported sludge amounts for the conveyorized facilities average 17,000 Ibs/year, or 9.5
Ibs per 1,000 ssf of PWB produced.
3-30
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3.1 SOURCE RELEASE ASSESSMENT
Reported sludge amounts for the non-conveyorized facilities, average 6,700 Ibs/year, or 27
Ibs per 1,000 ssf of PWB produced.
Metal concentrations in sludge could not be adequately characterized.
3.1.4 Uncertainties in the Source Release Assessment
Uncertainties and variations in the data include both gaps in knowledge (uncertainty) and
variability among facilities and process alternatives. These are discussed below.
For the IPC Workplace Practices Questionnaire and Performance Demonstration data:
• There may be uncertainties due to misinterpretation of a question, not answering a
question that applies to that facility, or reporting inaccurate information. Also, because of
a limited number of responses for the alternative processes, information more typical for
that process may not be reported.
• Variation includes variation within or among process alternatives, or difference due to
PWB ssf produced. Again, for MHC process alternatives with a limited number of
responses, statistical summaries of the data may be precluded, and data may not be
representative of most PWB facilities.
For the supplier-provided data:
• Knowledge gaps include a lack of information on proprietary chemicals, incomplete bath
composition data, and the reporting of wide ranges of chemical concentrations on a
MSDS rather then specific amounts in the formulations.
• Variation includes variation in bath chemistries and process specifications among
suppliers for a given process alternative. The publicly-available bath chemistry data,
chemical concentrations, and supplier recommendations may not apply to a specific
facility due to variation in process set-up and operation procedures.
Other uncertainties pertain to the applicability and accuracy of estimates and assumptions used in
this assessment.
3-31
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3.2 EXPOSURE ASSESSMENT
3.2 EXPOSURE ASSESSMENT
Evaluating exposure for the PWB CTSA involves a series of sequential steps. The first
step is characterizing the exposure setting, which includes describing the physical setting and
characterizing the population(s) of interest and their activities that may result in exposure. These
are described in Section 3.2.1 for both workplace and surrounding population (ambient)
exposure.
The next step is selecting a set of workplace and population exposure pathways for
quantitative evaluation from the set of possible exposure pathways. This is discussed in Section
3.2.2.
Next, chemical concentrations are collected or estimated in all media where exposure
could occur. For the MHC processes, this consists of collecting existing concentration data from
workplace monitoring, estimating the chemical concentrations in the MHC baths, and performing
fate and transport modeling to estimate workplace and ambient air concentrations (Section 3.2.3).
The exposure-point concentrations and other exposure parameters are combined in
exposure models to estimate potential dose rates (PDRs) for all quantified pathways. These
exposure models and parameter values are described in Section 3.2.4. The final step,
characterizing uncertainties, is in Section 3.2.5.
Because this CTSA is a comparative evaluation, and standardization is necessary to
compare results for the alternative processes, this assessment focuses on a "model" (generic)
PWB facility and uses aggregated data. In addition, this assessment focuses on exposure from
chronic, long-term, day-to-day releases from a PWB facility rather than short-term exposures to
high levels of hazardous chemicals as there could be with a fire, spill, or periodic releases. Due
to the limited resources available to the project and the lack of information to characterize such
releases, high level, acute exposures could not be assessed.
3.2.1 Exposure Setting
Characterizing the exposure setting includes the following steps:
• Characterizing the physical environment (in this case, a model PWB facility, its MHC
process area, and the surrounding environment).
• Identifying potentially exposed workers and their activities.
• Identifying any potentially exposed populations, human or ecological, that may be
exposed through releases to the ambient environment from PWB facilities.
• Defining the exposure scenarios to evaluate. (As used here, the term scenario refers to a
specified physical setting, exposed population, and activities that may result in exposure.)
Physical Environment
IPC Workplace Practices Questionnaire and Performance Demonstration data collected
for 59 PWB facilities and their MHC process areas were used to characterize a model PWB
facility. Information obtained from these sources includes the following:
_
-------
3.2 EXPOSURE ASSESSMENT
• Regarding MHC process alternatives, the IPC Workplace Practices Questionnaire
database includes information from 36 electroless copper facilities, two carbon facilities,
one conductive polymer facility, four graphite facilities, one non-formaldehyde copper
facility, two organic-palladium facilities, and 13 tin-palladium facilities.
• Of these facilities, 48 are independent and the other 11 are original equipment
manufacturers (OEMs) who manufacture PWBs solely for use in that company's
products.
The size of the PWB manufacturing area ranges from 3,721 to 400,000 ft2, with a
geometric mean area of 33,800 ft2.
• The size of the MHC process room ranges from 120 to 60,000 ft2, with a geometric mean
of 3,760 ft2.
• The number of days per year the MHC line operates ranges from 80 to 360, with an
average of 250 days/year and a 90th percentile of 306 days/year.
• The total PWB processed per year ranges from 24,000 ssf per year to 6.24 million ssf per
year, with a geometric mean of 351,670 ssf per year.
• Temperature of the process room ranges from 60 to 94 °F, with an average of 75 °F.
• All 59 facilities responding to the question reported the use of some type of ventilation in
the process area. A smaller number of facilities provided more specific information on
the type of ventilation and air flow rates. Reported air flow rates range from 7 to 405,000
ftVmin. with a geometric mean of 6,100 ftVmin. Of the facilities reporting air flow rates,
the types of ventilation reported are as follows:
- Seven facilities reported using both local and general ventilation systems.
- Six facilities reported using only general ventilation.
- Twenty-three facilities reported using only local ventilation. (However, they may not
have consistently reported general ventilation.)
- One facility did not specify either local or general ventilation.
The initial intent was to focus on a generic small- to medium-sized facility that
manufactures < 6,000 ssf of PWB per day. However, larger facilities are now included in the
database to account for all of the performance demonstration sites and all categories of process
alternatives. The conductive ink facility is not included in this assessment.
The data summarized here are used to broadly characterize the exposure setting (i.e., a
model PWB facility and MHC process area). Data used in the exposure models are discussed
further in Section 3.2.4. Based on the workplace practices data and using arithmetic averages or
geometric means, a model facility has the following characteristics:
• Is independent (rather than OEM).
• Uses 33,800 ft2 of facility space in the PWB operation.
• Contains the MHC process in a room 3,760 ft2 in size.
• Operates an MHC line 250 days/year.
Manufactures 350,000 ssf of PWB per year.
• Is 75 °F in the process room.
• Has a typical ventilation air flow rate in the process area of 6,100 ftVmin.
3-33
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3.2 EXPOSURE ASSESSMENT
Potentially Exposed Populations
Potentially exposed populations include both workers in the PWB facilities and
ecological and human populations in the vicinity of the facilities. Each of these populations is
discussed briefly below.
General Employee Information from the IPC Workplace Practices Questionnaire.
A summary of IPC Workplace Practices Questionnaire data pertaining to employees at PWB
facilities includes the following:
• The number of full-time employee equivalents (FTEs) ranges from 8 to 1,700, with a
geometric mean of 103.
• The number of employee work days per year ranges from 200 to 360, with an average of
268 days/year. The number of days per year the MHC line operates is used to
characterize worker exposure from MHC line operation, rather than the overall employee
work days per year, because the latter could include workers not in the MHC process area
or time when the MHC line is not in operation.
• The MHC process line operates from 1 to 12 hours/shift, with an average of 6.8
hours/shift.
• Fifty-eight out of 59 facilities reported a first shift, 52 a second shift, 29 a third shift, and
one reported a fourth shift (one facility operates the second but not a first shift). For
MHC operation, 54 facilities reported a first shift, 43 a second shift, 16 a third shift, and
one reported a fourth shift. This exposure assessment uses first shift data as
representative.
• Types of workers in the MHC process area include:
- Line operators.
- Laboratory technicians.
- Maintenance workers.
- Supervisory personnel.
- Wastewater treatment operators.
- Contract workers.
- Other employees (i.e., manufacturing engineer, process control specialist).
General Population Outside the Facility. PWB facilities included in the IPC
Workplace Practices Questionnaire and Performance Demonstration database are located in
various cities in the U.S. and Europe. Many are in southern California. This assessment
estimates potential exposure to a hypothetical community living near a model PWB facility.
Exposure to ecological populations could also occur outside a PWB facility. In past
CTSAs, concentrations have been estimated for surface water to assess potential exposure to
aquatic organisms. However, as discussed in the Source Release Assessment (Section 3.1), data
limitations preclude estimating releases to surface water. Ecological toxicity and hazard for
potential releases to surface water (based on bath constituents used in each alternative) are
addressed in Section 3.3.
3-34
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3.2 EXPOSURE ASSESSMENT
Workplace Exposure Scenarios
A scenario describes the exposure setting, potentially exposed populations or individuals,
and activities that could lead to exposure. For workplace exposures, the setting involves the
MHC process in a PWB facility. The Workplace Practices data are used here to determine the
types of workers who may be exposed and to characterize those worker's activities. Worker
activities include working in the process area, MHC line operation, chemical bath sampling,
chemical bath additions, chemical bath replacement, rack cleaning, conveyor equipment
cleaning, and filter replacement.
Working in the Process Area. Exposure via inhalation of airborne chemicals is possible
to workers in the MHC process area. Because of this, the questionnaire included questions about
the types of workers who might be present in the area. Out of 59 facilities responding to this
question:
Fifty-nine have line operators in the MHC process area during the first shift.
Fifty-two have laboratory technicians in the MHC process area.
Thirty-eight have maintenance workers in the MHC process area.
Fifty have supervisory personnel in the MHC process area.
Thirty-six have wastewater treatment operators in the MHC process area.
Two have contract workers in the MHC process area.
Six have other employees in the MHC process area.
MHC Line Operation. Potential for exposure during MHC line operation is expected to
vary significantly among process methods. In manual, non-conveyorized methods, a line
operator stands at the bath and manually lowers and raises the panel racks into and out of each
bath. A vertical/automated method is completely automated, where panel racks are lowered and
raised into vertical tanks by a robotic arm; line operators load and unload panels from the racks.
A manually-controlled vertical hoist is a semi-automated system where racks are lowered into
and raised out of a series of vertical chemical baths by a line operator-controlled hoist. The hoist
is controlled by a hand-held control panel attached to the hoist by a cable. The conveyorized
method is an automated method where panels are transported into and out of process baths by
means of a conveyor; line operators load and unload panels from the conveyor system. Based on
the workplace practices data:
• For electroless copper lines, 35 out of 36 are non-conveyorized, of which 19 are
vertical/automated, ten are manually controlled vertical hoist, and six are manual (with no
automation). One facility is conveyorized.
• All carbon and graphite lines in the database are conveyorized.
• The single conductive polymer system is conveyorized.
• The single non-formaldehyde electroless copper system is non-conveyorized, with
manually controlled vertical hoist.
• For organic-palladium lines, one is conveyorized and one is non-conveyorized with a
vertical/automated system.
For tin-palladium lines, 13 are non-conveyorized, of which one is vertical/automated,
four are manually controlled vertical hoist, and six are manual (no automation). Two
facilities are conveyorized.
3-35
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3.2 EXPOSURE ASSESSMENT
Different assumptions are made about worker exposure for non-conveyorized and
conveyorized systems. For the non-conveyorized systems, it is assumed that workers manually
lower and raise panel racks. This is a conservative but consistent assumption made for all non-
conveyorized process alternatives.
Chemical Bath Sampling. Based on the questionnaire database, chemical baths in the
carbon, graphite, and organic-palladium alternatives are normally sampled by use of a drain or
spigot on the bath. For electroless copper, the most common method is to dip a container (ladle,
beaker, or sample bottle) into a bath. For tin-palladium, the most common method reported is to
sample by pipette.
Chemical Bath Additions. Methods of chemical additions from the database are as
follows:
• Most facilities pour chemical additions directly into the bath or tank (63 percent).
• Other reported options include: stirring into a tank (24 percent), pouring into an
automated chemical addition system (20 percent), or other (two percent). Stirring
typically involves fluid agitation while pouring the formulation into the bath.
• For carbon and graphite facilities, 100 percent reported pouring directly into the tanks.
This activity is characterized for a model facility by pouring chemicals directly into the tank for
all process alternatives except conductive polymer, where all additions are made automatically.
Chemical Bath Replacement. This process includes removing the spent bath, cleaning
the empty tank, and making up fresh bath solutions. In this process, a worker could be exposed
to chemicals in the spent bath, on the inside walls of the emptied bath, or to chemicals in the new
bath solution.
Rack Cleaning. Rack cleaning only applies to those process alternatives where a buildup
of material on the panel racks occurs (e.g., copper plating onto the racks). This includes the
electroless copper, non-formaldehyde electroless copper, and tin-palladium processes. Rack
cleaning for these processes could occur either as part of the routine MHC line operation (called
"continuous" rack cleaning) or as a separate step in the process. Of the facilities responding to
this question, only nine out of 36 electroless copper facilities and four out of 13 tin-palladium
facilities reported rack cleaning as a separate step in the process. An additional 17 electroless
copper facilities reported continuous rack cleaning. All of the remaining facilities reported the
question was not applicable, did not respond, or gave an unusable response.
Because there were a low number of applicable or usable responses to the question, and a
majority of the electroless copper facilities responding to the question use continuous rack
cleaning, this activity is not considered quantitatively as a separate worker activity performed at a
model facility.
Conveyor Equipment Cleaning. Conveyor equipment cleaning involves regular
equipment maintenance for conveyorized MHC lines; 11 of the facilities in the database are
conveyorized. Examples include cleaning the fluid circulation heads and rollers for the graphite
process, and vacuuming particulates from the drying areas of graphite and carbon lines.
_
-------
3.2 EXPOSURE ASSESSMENT
Filter Replacement. Filter replacement could result in exposure to the material on the
filter or in the bath. Whether the pathway is significant to worker risk will depend, in part, on the
chemical constituents in the bath.
Use of Personal Protective Equipment (PPE). An overview of the data pertaining to
the use of PPE indicates the following general trends for the various activities:
• Most facilities reported the use of eye protection and gloves, but some did not.
• Use of lab coats or aprons was reported approximately 1/4 to 1/2 of the time.
• Few facilities reported using boots.
• The use of respiratory protection was very rarely reported.
It is assumed that the only PPE used is eye protection and that the line operator's hands
and arms may contact bath solutions. This is a conservative but consistent assumption for all
process alternatives and worker activities, particularly for dermal exposure. While most PWB
facilities reported that line operators do wear gloves, the assumption that the line operator's
hands and arms may contact bath solutions is intended to account for the fraction of workers who
do not. For workers who do wear gloves, dermal contact exposure is expected to be negligible.
Summary of Scenarios. MHC Line Operators. In general, line operators perform
several activities, including MHC line operation (which includes working in the MHC process
area); chemical bath replacement; rack cleaning; conveyor equipment cleaning; filter
replacement; chemical bath sampling; making chemical bath additions; and bail-out of baths.
Some kind of local ventilation is typically used for the process line.
There are two different scenarios for line operators depending on process configuration.
For non-conveyorized processes, dermal exposure could occur through routine line operation as
well as bath maintenance activities. Inhalation exposure could occur throughout the time period
a line operator is in the MHC process area. Conveyorized processes are enclosed and the line
operator does not contact the bath solutions in routine line operation; he or she only loads panels
at the beginning of the process and unloads them at the end of the process. For conveyorized
processes, dermal exposure is primarily expected through bath maintenance activities such as
bath replacement, bath sampling, and conveyor equipment cleaning. Because the conveyorized
lines are enclosed and typically vented to the outside, inhalation exposure to line operators and
other workers is assumed to be negligible for the conveyorized processes.
Laboratory Technicians. In general, laboratory technicians perform one activity
pertaining to the MHC line, chemical bath sampling, in addition to working in the MHC process
area. Bath sampling exposure is quantified separately for laboratory technicians.
Other Workers in the MHC Process Area. Other workers in the MHC process area may
include maintenance workers, supervisory personnel, wastewater treatment operators, contract
workers, and other employees. They perform activities not directly related to the MHC line, but
typically spend some time in the MHC process area. Because the line operators spend the most
amount of time per shift, exposure via inhalation is quantified for them (for non-conveyorized
processes), and characterized for the other employees in terms of the time spent in the process
area relative to line operators.
3-37
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3.2 EXPOSURE ASSESSMENT
3.2.2 Selection of Exposure Pathways
The definition of exposure scenarios leads to selection of the exposure pathways to be
evaluated. An exposure scenario may comprise one or several pathways. A complete exposure
pathway consists of the following elements:
• A source of chemical and mechanism for release.
• An exposure point.
• A transport medium (if the exposure point differs from the source).
• An exposure route.
Tables 3.6 and 3.7 present an overview of the pathways selection for workplace and
surrounding population exposures, respectively. For the workplace, another potential pathway
not quantified is oral exposure to vapors or aerosols. For example, oral exposure could occur if
inhaled chemicals are coughed up and then swallowed.
Population exposures may occur through releases to environmental media (i.e., releases to
air, water, and land). The only pathway for which exposure is estimated is inhalation of
chemicals released from a facility to a nearby residential area. Approaches for the three
environmental media are described below.
Air
Air releases from the MHC process are modeled for the workplace. Those modeled
emission rates are used in combination with an air dispersion model to estimate air
concentrations to a nearby population.
Surface Water
Little reliable data are available for water releases for the MHC alternatives. (This issue
is discussed further in Section 3.2.3.) Exposures and risks from surface water are evaluated
qualitatively by identifying chemicals potentially released to surface water from the publicly-
available bath chemistry data (discussed in Section 2.1.4), bath chemistry data for disclosed
proprietary ingredients, and using ecological toxicity data to highlight those chemicals of highest
ecological concern if released to surface water (Section 3.3).
Land
Possible sources of releases to land from MHC processes include bath filters and other
solid wastes from the process line, chemical precipitates from baths, and sludge from wastewater
treatment. These are discussed in Section 3.1, Source Release Assessment. Reliable
characterization data for potential releases to land are not available; therefore, the exposure
assessment does not estimate the nature and quantity of leachate from landfills or effects on
groundwater.
3-38
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3,2 EXPOSURE ASSESSMENT
Table 3.6 Workplace Activities and Associated Potential Exposure Pathways
Activities
Potential Pathways
Evaluation Approach and Rationale
Line Operators"
MHC Line Operation
Working in Process Area
Chemical Bath Replacement;
Conveyor Equipment
Cleaning; Filter Replacement;
Chemical Bath Sampling
Rack Cleaning
Chemical Bath Additions
Dermal contact with
chemicals in MHC baths.
Inhalation of vapors or
aerosols from MHC baths.
Inhalation of vapors or
aerosols from MHC baths.
Dermal contact with
replacement chemicals.
Inhalation of vapors or
aerosols from MHC baths.
Dermal contact with
chemicals on racks.
Inhalation of vapors or
aerosols from MHC baths.
Dermal contact with
chemicals added.
Inhalation of vapors or
aerosols from MHC baths
or while making bath
additions.
Exposure quantified for non-conveyorized
lines; the highest potential dermal exposure
is expected from this activity. Exposure for
conveyorized lines assumed to be negligible
for this activity.
Exposure quantified for non-conveyorized
lines. Exposure for conveyorized lines
assumed to be negligible.
Exposure quantified for non-conveyorized
lines.
Exposure quantified for conveyorized lines
for all activities together (bath sampling
quantified separately for laboratory
technicians). Exposure not quantified
separately for these activities on non-
conveyorized lines.
Not quantified separately. Included in
"working in process area" for non-
conveyorized lines; not quantified due to
modeling limitations for conveyorized lines.
Not quantified; limited data indicate this is
not performed by many facilities.
Not quantified separately. Included in
"working in process area" for non-
conveyorized lines; not quantified due to
modeling limitations for conveyorized lines.
Not quantified separately from chemicals
already in the baths.
Not quantified separately. Included in
"working in process area" for non-
conveyorized lines; not quantified due to
modeling limitations for conveyorized lines.
Laboratory Technicians
Chemical Bath Sampling
Working in Process Area
Dermal contact with
chemicals in MHC baths.
Inhalation of vapors or
aerosols from MHC baths.
Inhalation of vapors or
aerosols from MHC baths.
Exposure quantified for conveyorized and
non-conveyorized lines.
Not quantified separately (included in
"working in process area").
Exposure quantified for line operators for
non-conveyorized lines; exposure for other
workers is proportional to their exposure
durations.
3-39
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3.2 EXPOSURE ASSESSMENT
Activities
Potential Pathways
Evaluation Approach and Rationale
Maintenance Workers, Supervisory Personnel, Wastewater Treatment Operators, Contract
Workers, and Other Workers
Working in Process Area
Inhalation of vapors or
aerosols from MHC baths.
Dermal contact with
chemicals in MHC baths.
Exposure quantified for line operators for
non-conveyorized lines; exposure for other
workers is proportional to their exposure
durations.
Not quantified.*
* This assumes MHC line operators are the most exposed individuals and perform all direct maintenance on the
MHC line, including filter replacement and equipment cleaning.
Table 3.7 Potential Population Exposure Pathways
Population
Residents Living
NearaPWB
Facility
Ecological
Potential Pathways
Inhalation of chemicals released to air.
Contact with chemicals released to surface
water directly or through the food chain.
Exposure to chemicals released to land or
groundwater.
Exposure to chemicals released to surface
water.
Exposure to chemicals released to air or
land.
Evaluation Approach and Rationale
Exposure quantified for all potential
carcinogens and any other chemical
released at a rate of at least 23 kg/year.
Not evaluated.
Not evaluated.
Evaluated qualitatively in the Human
Health and Ecological Hazards Summary
(Section 3. 3).
Not evaluated.
3.2.3 Exposure-Point Concentrations
The term exposure-point concentration refers to a chemical concentration in its transport
or carrier medium, at the point of contact (or potential point of contact) with a human or
environmental receptor. Sources of data for the Exposure Assessment include monitoring data,
publicly-available bath chemistry data, some proprietary bath chemistry data, and fate and
transport models to estimate air releases and air concentrations. Concentrations for dermal
exposure in the baths are those estimated from publicly-available bath chemistry data, as
described in Section 2.1.4, and from disclosed proprietary ingredient information. Fate and
transport modeling were performed to estimate air concentrations for workplace and surrounding
population exposures as described in this section.
Monitoring Data
Table 3.8 presents a summary of all available Federal Occupational Safety and Health
Administration (OSHA) data for PWB manufacturers (standard industrial code [SIC] 3672).
California OSHA was also consulted for monitoring data; they referred to the Federal OSHA
database. In addition, one facility submitted results of monitoring for formaldehyde at 0.06 ppm
(8 hr. time-weighed average [TWA]) along with their response to the IPC Workplace Practices
Questionnaire.
3-40
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3.2 EXPOSURE ASSESSMENT
It should be noted that OSHA monitoring is typically performed only for those chemicals
which are regulated by OSHA (i.e., chemicals with permissible exposure limits [PELs]).
Monitoring also does not distinguish between the MHC process and other parts of the PWB
process that may be located in the same area.
Table 3.8 Summary of Federal OSHA Monitoring Data for PWB Manufacturers
(SIC 3672)
Chemical
Ammonia
Copper Sulfate, as Copper
Ethanolamine
Formaldehyde
Hydrochloric Acid
Isopropanol
Methanol
Phosphoric Acid
Sodium Hydroxide
Stannous Chloride, as Tin
Sulfuric Acid
No. of Data Points/
No. of Facilities
26/6
11/2
5/1
43/11
26/5
16/4
6/1
3/1
33/6
26/10
28/11
Range
(ppm)
0-27
0-0
0 - 0.09
0 - 4.65
0-0
0-215
0-0
0-0
0-2.3
0-0.113
0 - 0.24
Average
(ppm)"
6.9
0
0.02
0.44
0
41.7
0
0
0.359
0.006
0.045
Standard Deviation
(ppm)
8.24
0
0.04
0.75
0
57.6
0
0
0.614
0.023
0.070
a Zeros were included in averages; detection limits were not reported.
Modeling Workplace Air Concentrations
Bath concentrations estimated from publicly-available chemistry data and disclosed
proprietary chemical data, as well as process configurations from the IPC Workplace Practices
Questionnaire, were used to estimate workplace and ambient air concentrations using fate and
transport models (Robinson et al., 1997). This section describes air transport models to estimate
worker inhalation exposure to chemicals from PWB MHC lines. Three air transport models are
used to estimate worker exposure:
1. Volatilization of chemicals induced by air sparging.
2. Aerosol generation Induced by air sparging.
3. Volatilization of chemicals from the open surface of MHC tanks.
For models 1 and 31 volatilization was modeled only for those chemicals with a vapor
pressure above 10~3 torr (a vapor pressure less than 10"3 torr was assumed for inorganic salts even
if vapor pressure data were not available). Aerosol generation and volatilization from air-sparged
baths were modeled only for those baths that are mixed by air sparging as indicated in the
Workplace Practiceis and Performance Demonstration data; this includes the electroless copper
baths and some cleaning tanks. The total transport of chemicals from the air-sparged baths was
determined by summing the releases from each of the three models. The third model was applied
to determine volatilization of chemicals from un-sparged baths. A review of the relevant
literature, descriptions of the models, and examples demonstrating the use of the models are
available in the December 22,1995 Technical Memorandum, Modeling Worker Inhalation
3-41
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3.2 EXPOSURE ASSESSMENT
Exposure (Appendix D). Modeled emission rates and workplace air concentrations are presented
in Table 3.9. Proprietary chemical results are not presented in order to protect proprietary
chemical identities.
Table 3.9 Results of Workplace Air Modeling
Chemical*
Emission
Rate
(mg/min)
Air
Cone.
(mg/mj)
Federal OSHA and/or NI0SH
Permissible Inhalation Exposure
Limits (mg/rn3)*
Electroless Copper, non-conveyorized
Ammonium Chloride
Benzotriazole
Boric Acid
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Dimethylaminoborane
Dimethylformamide
2-Ethoxyethanol
Ethanolamine
Ethylene Glycol
Ethylenediaminetetraacetic Acid (EDTA)
Fluoroboric Acid
Formaldehyde
Formic Acid
Hydrochloric Acid
Hydrogen Peroxide
Hydroxyacetic Acid
Isopropyl Alcohol; or 2-Propanol
m-Nitrobenzene Sulfonic Acid
Magnesium Carbonate
Methanol
p-Toluene Sulfonic Acid
Palladium
Peroxymonsulfuric Acid
Potassium Bisulfate
Potassium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium Sulfate
Potassium-Sodium Tartrate
Sodium Bisulfate
Sodium Carbonate
Sodium Chlorite
NA
1.24&-01
1.71e-01
7.56e-02
8.31e-02
1.94e+00
1.42e+00
1.46e+03
9.92e+00
3.33e+00
5.11e-01
2.20e+00
1.37e401
3.51e+01
5.43e-03
1.66e-01
3.14e-02
5.24e+02
9.14e-04
9.99e-03
2.31e+02
NA
NA
2.15e-01
1.15e-01
2.52e-03
2.33e-03
8.16e-02
1.60e-01
3.556-01
NA
5.65e-04
NA
NA
5.54e-03
7.64e-03
3.38e-03
3.71e-03
8.66e-02
6.33e-02
6.51e+01
4.44e-01
1.49e-01
2.29e+02
9.82e-02
6.15e-01
1.57e400
2.43e-04
7.41e-03
1.40e-03
2.34e+01
4.09e-05
4.47e-04
1.03e+01
NA
NA
9.60e-03
5.14e-03
1.13e-04
1.046-04
3.65e-03
7.15e-03
1.59e-02
NA
2.53e-05
NA
10 (NIOSH)
1 (as Cu dust and mist; OSHA/NIOSH)
1 (as Cu dust and mist; OSHA/NIOSH)
30 (OSHA/NIOSH)
740 (OSHA); 1.8 (NIOSH)
6 (OSHA)
0.94 (0.75 ppm)° (OSHA)
9 (OSHA/NIOSH)
7 (NIOSH)
1.4 (OSHA/NIOSH)
980 (OSHA)
260 (OSHA/NIOSH)
5 (as CN; OSHA/NIOSH)
2 (NIOSH)
3-42
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3.2 EXPOSURE ASSESSMENT
Chemical8
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Sulfate
Stannous Chloride
Sulfuric Acid
Tartaric Acid
Triethanolamine; or 2,2',2"-Nitrilotris
ithanol
Emission
Rate
(mg/min)
2.61e-03
L18e-01
NA
NA
NA
1.24e+00
1.17e-02
NA
Non-Formaldehyde Electroless Copper, non-conve
Copper Sulfate; or Cupric Sulfate
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or 2-Propanol
Potassium Hydroxide
Potassium Persulfate
Sodium Chlorite
Sodium Hydroxide
Stannous Chloride
Sulfuric Acid
2.74e-01
NA
9.36e-02
7.34e+01
1.49e-03
5.68e-02
NA
1.74e-03
NA
1.48e-01
Air
Cone.
(mg/m3)
1.17e-04
5.26e-03
NA
NA
NA
5.57e-02
5.21e-04
NA
Federal OSHA and/or NIOSH
Permissible Inhalation Exposure
Limits (mg/m3)b
5 (as CN; OSHA/NIOSH)
2 (OSHA/NIOSH)
2 (as Sn; OSHA)
1 (OSHA)
^orized
1.22e-02
NA
4.19e-03
3.28e+00
6.67e-05
2.54e-03
NA
7.78e-05
NA
6.63e-03
1 (as Cu dust and mist; OSHA/NIOSH)
7 (NIOSH)
1.4 (OSHA/NIOSH)
980 (OSHA)
2 (NIOSH)
2 (OSHA/NIOSH)
2 (as Sn; OSHA)
1 (OSHA)
Organic-Palladium, non-conveyorized
Hydrochloric Acid
Sodium Bisulfate
Sodium Carbonate
Sodium Hypophosphite
Sodium Persulfate
Trisodium Citrate 5.5-Hydrate; or
Sodium Citrate
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
7 (NIOSH)
Tin-Palladium, non-conveyorized
1,3-Benzenediol
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Ethanolamine
Fluoroboric Acid
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or 2-Propanol
Lithium Hydroxide
Palladium
NA
NA
7.38e-02
2.00e+01
1.76e+00
NA
9.71e-02
2.94e+02
NA
NA
NA
NA
3.30e-03
8.92e-01
7.89e-02
NA
4.34e-03
1.32e+01
NA
NA
1 (as Cu dust and mist; OSHA/NIOSH)
1 (as Cu dust and mist; OSHA/NIOSH)
6 (OSHA)
7 (NIOSH)
1.4 (OSHA/NIOSH)
980 (OSHA)
3-43
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3.2 EXPOSURE ASSESSMENT
Chemical1*
Palladium Chloride
Potassium Carbonate
Sodium Bisulfate
Sodium Chloride
Sodium Hydroxide
Sodium Persulfate
Stannous Chloride
Sulfuric Acid
Triethanolamine; or 2,2',2"-Nitrilotris
Ethanol
Vanillin
Emission
Rate
(mg/imn)
NA
NA
NA
NA
NA
8.38e-01
NA
1.16e-01
NA
8.09e-02
Air
Cone.
(mg/rn3)
NA
NA
NA
NA
NA
3.75e-02
NA
5.19e-03
NA
3.62e-03
Federal OSHA and/or NIOSH
Permissible Inhalation Exposure
Limits (mg/m3)b
2 (OSHA/NIOSH)
2 (as Sn; OSHA)
1 (OSHA)
* Proprietary chemical results are not presented in order to protect proprietary chemical identities.
b Source: NIOSH, 1994 and 29 CFR 1910.1000, Table Z-l.
0 OSHA has set an "action level" of 0.5 ppm for formaldehyde. At or above that level, people working in the area of
exposure must be monitored, and the area must be segregated. From 0.1 - 0.5 ppm, workers must be notified that
formaldehyde is present (but not that it is suspected of being a carcinogen).
NA: Not Applicable. A number was not calculated because the chemical's vapor pressure is below the 1 x 10"3 ton-
cutoff and is not used in any air-sparged bath. Therefore, ah- concentrations are expected to be negligible.
Note: The numeric format used in these tables is a form of scientific notation, where the "e" replaces the " x 10"" hi
scientific notation. Scientific notation is typically used to present very large or very small numbers. For example,
1.2e-04 is the same as 1.2 x 10"4, which is the same as 0.00012 in common decimal notation.
Volatilization of Chemicals from Air-Sparged MHC Tanks. Mixing in plating tanks
(e.g., the electroless copper plating tank) is commonly accomplished by sparging the tank with
air. The equation used for predicting the mass transfer rate from an aerated system is based on
volatilization models used in research of aeration in wastewater treatment plants:
1 -exp
where:
H
= mass transfer rate of chemical^ out of the system by sparging (mg/min)
= gas flow rate (L/min)
= dimensionless Henry's Law Constant (Hc) for chemical >>
= concentration of chemical y in bulk liquid (mg/L)
= overall mass transfer coefficient for chemical y (cm/min)
a = interfacial area of bubble per unit volume of liquid (cm2/cm3)
VL = volume of liquid (cm3)
Aerosol Generation from Baths Mixed by Sparging with Air. Aerosols or mists are
also a potential source of contaminants from electroless baths. The rate of aerosol generation has
been found to depend on the air sparging rate, bath temperature, air flow rate above the bath, and
the distance between bath surface and the tank rim. The following equation is used to estimate
the rate of aerosol generation (Berglund and Lindh, 1987):
3-44
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3.2 EXPOSURE ASSESSMENT
RA =5.5x10
where:
QG
A
FT
FA
FD
= aerosol generation rate (ml/min/m2)
= air sparging rate (cmVmin)
= bath area (m2)
= temperature correction factor
= air velocity correction factor
= distance between the bath surface and tank rim correction factor.
The emission of contaminants resulting from aerosols depends on both the rate of aerosol
generation and the concentration of contaminants in the aerosol. The following equation is used
to estimate contaminant emission (flux) from aerosol generation:
M.
EI _ £_ f p
r v.a , . JIB r •
IE y,s
where:
• y,a
M
rate of mass transfer from the tank to the atmosphere by aerosols (mg/rnin)
fraction of bubble interface ejected as aerosols (dimensionless)
mass of contaminant at the interface (mg)
mass of contaminant in gas bubble (mg)
The literature on aerosol generation indicates that the typical size of aerosols is one to ten
microns; this is important to note because particles in this range are more inhalable. Larger sized
particles tend to fall back into baths rather than remaining airborne and dispersing throughout the
room.
Volatilization of Chemicals from the Open Surface of MHC Tanks. Most plating
tanks have a free liquid surface from which chemicals can volatilize into the workplace air. Air
currents across the tank will accelerate the rate of volatilization. The EPA's Chemical
Engineering Branch (CEB) Manual (EPA, 199la) suggests the following model for evaporation
of chemicals from open surfaces:
Fy,0 = 1200
Hy A
-10.5
where:
CL,y
Hy
D
y,air
"z
Z
A
= volatilization rate of chemical y from open tanks (mg/min)
= concentration of chemical y in bulk liquid (mg/L)
= dimensionless Henry's Law Constant (Hc) for chemical y
= molecular diffusion coefficient of chemical y in air (cmVsec)
= air velocity (m/sec)
= distance along the pool surface (m)
= bath area (m2)
Some limitations of the model should be pointed out. The model was developed to
predict the rate of volatilization of pure chemicals, not aqueous solutions. The model was also
3-45
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3.2 EXPOSURE ASSESSMENT
derived using pure chemicals. As a result, Hie model implicitly assumes that mass transfer
resistance on the gas side is the limiting factor. The model may overestimate volatilization of
chemicals from solutions when liquid-side mass transfer is the controlling factor.
Calculation of Chemical Concentration in Workplace Air from Emission Rates. The
indoor air concentration is estimated from the following equation (EPA, 199la):
= Fy,T/(VRRvk)
where:
•y,T
^R
\.v
= workplace contaminant concentration (mg/m3)
= total emission rate of chemical from all sources (mg/min)
= room volume (m3)
= room ventilation rate (min"1)
= dimensionless mixing factor
The mixing factor accounts for slow and incomplete mixing of ventilation air with room
air. A value of 1.0 was used for this factor. The CEB Manual commonly uses values of the
ventilation rate Q from 500 ft3/min to 3,500 ft3/min. Ventilation rates for MHC lines were
determined from the facility data. An air turnover rate of 0.021 per minute (1.26 per hour) was
used, which is based on estimated air turnover rates that yield 90th percentile air concentrations
from Monte Carlo analysis. (This is explained in detail in Appendix D.) An average room
volume was used from questionnaire data assuming a ten foot room height.
Other assumptions pertaining to these air models include the following:
Deposition on equipment, condensation of vapors, and photodegadation are negligible.
Incoming air is contaminant-free.
The concentration of contaminant at the beginning of the day is zero.
As much air enters the room as exits through ventilation (mass balance).
• Room air and ventilation air mix ideally.
Sensitivity Analysis. Model sensitivity and uncertainty was examined using Monte
Carlo analysis with the air transport equations outlined above and probability distributions for
each parameter based on data from the IPC Workplace Practices Questionnaire (see Appendix D
for details). This was done with a Monte Carlo software package (Crystal Ball™
[Decisioneering, Inc., 1993]) in conjunction with a spreadsheet program.
This analysis suggested that a few parameters are key to modeling chemical flux from
PWB tanks. These key parameters are air turnover rate, bath temperature, chemical
concentration in the bath, and Henry's Law Constant.
The air model's sensitivity to these parameters and their uncertainty provides a means of
isolating them from less important variables. Isolating these variables allows for additional
scrutiny to be placed upon the point estimate assumptions used for them in the volatilization
models.
3-46
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3.2 EXPOSURE ASSESSMENT
The air turnover rate assumption contributes most to overall model variance. The
chemical bath concentration and bath temperature also contribute variance to the model, but are
less important than air turnover rate. This statement is fortified by the fact that relatively
accurate information is available on their distributions. Hc appears to be least important of the
four, but may have more variability associated with it. The models appear to be largely
indifferent to small changes in most other parameters.
Modeling Air Concentrations for Population Exposure
The following approach was used for dispersion modeling of air emissions from a single
facility:
• Model: Industrial Source Complex Long Term ISC(2)LT model from the
Risk* Assistant™ software.
• Building (release) height: 3m.
» Area source: 10 x 10m.
• Meteorological data: an average emission rate-to-air concentration factor of 2.18 x 10"6
min/m3 was determined using data for Oakland, California; Denver, Colorado; and
Phoenix, Arizona. (These three areas give the highest modeled concentrations around a
facility for any available city data in the model.)
• Other parameters: regulatory default values were used. (These are model defaults
pertaining to plume rise, stack-tip downwash, buoyancy-induced dispersion, wind profile
exponents, vertical temperature gradient, and buildings adjacent to the emission source.)
• Setting: urban mode. (The setting can be either rural or urban. The urban setting is
appropriate for urban areas or for large facilities.)
• Chemical degradation in air: not included in modeling.
• Location for exposure point concentrations: a standard polar grid3 with 36 vector
directions and one distance ring (at 100m) was used; the highest modeled air
concentration in any direction at 100 meters was used to estimate population exposure.
Because of the short time expected for chemical transport to nearby residents, chemical
degradation is not taken into account. The emission rates calculated for workplace inhalation
exposures are used for the source emission rates to ambient air. Ambient air concentrations were
not modeled for those chemicals with facility emission rates less than 23 kg/year (44 mg/min),
with the exception of formaldehyde, which was included because it is a potential carcinogen.
Results of ambient air modeling are presented in Table 3.10. Proprietary chemical results are not
presented to protect proprietary chemical identities.
3 A polar grid is a coordinate system that describes the location of a point by means of direction and distance in
relation to a central point (e.g., two miles northeast of the center). In the model, a series of regularly-spaced
concentric distance rings are defined at chosen intervals along with a defined number of direction vectors (e.g.,
north, south, east, west, northeast, northwest, southeast, and southwest would be eight directions).
£47
-------
3.2 EXPOSURE ASSESSMENT
Table 3.10 Results of Ambient Air Modeling
Chemical"
Emission Rateb
(mg/mitt)
Air Cone,
(mg/rtl3)
Electroless Copper, non-conveyorized
2-Ethoxyethanol
Formaldehyde
Isopropyl Alcohol; or 2-Propanol
Methanol
1.46e+03
1.37e+01
5.24e+02
2.31e+02
3.17e-03
3.00e-05
1.14e-03
5.03e-04
Electroless Copper, conveyorized
2-Ethoxyethanol
Formaldehyde
Formic Acid
Isopropyl Alcohol; or 2-Propanol
Methanol
1.55e+03
3.66e+01
7.90e+01
1.04e+03
4.28e+02
3.38e-03
7.97e-05
1.72e-04
2.26e-03
9.34e-04
Non-Formaldehyde Electroless Copper, non-conveyorized
Isopropyl Alcohol; or 2-Propanol
7.34e+01
1.60e-04
Tin-Palladium, non-conveyorized
Isopropyl Alcohol; or 2-Propanol
2.94e+02
6.42e-04
Tin-Palladium, conveyorized
Ethanolamine
Isopropyl Alcohol; or 2-Propanol
5.23e+01
2.34e+02
1.146-04
5.11e-04
* Proprietary chemical results are not presented in order to protect proprietary chemical identities.
b Only those chemicals with an emission rate at least 23 kg/year (44 mg/min), plus formaldehyde, are listed. Carbon,
conductive polymer, graphite, and organic-palladium had no modeled emission rates above this cut-off.
Note: The numeric format used in these tables is a form of scientific notation, where the "e" replaces the " x 10X" in
scientific notation. Scientific notation is typically used to present very large or very small numbers. For example,
1.2e-04 is the same as 1.2 x 10"4, which is the same as 0.00012 in common decimal notation.
Surface Water
Environmental releases to surface water were not quantified because chemical
constituents and concentrations in wastewater could not be adequately characterized for the MHC
line alone. This is because PWB manufacturers typically combine wastewater effluent from the
MHC process line with effluent from other PWB manufacturing processes prior to on-site
wastewater pretreatment. The pretreated wastewater is then discharged to a POTW. Many PWB
manufacturers measure copper concentrations in effluent from on-site pretreatment facilities in
accordance with POTW discharge permits, but they do not measure copper concentrations in
MHC line effluent prior to pretreatment. Because there are many sources of copper-
contaminated wastewater in PWB manufacturing, the contribution of the MHC line to overall
copper discharges could not be estimated. Furthermore, most of the MHC alternatives contain
copper, but because these technologies are only now being implemented in the U.S., their
influence on total copper discharges from a PWB facility cannot be determined. Finally, while
data are available on copper discharges from PWB facilities, data are not available for some of
the other metals found in alternatives to electroless copper. Although ecological hazards are
assessed in Section 3.3, without exposure or release data ecological risk could not be addressed
in the risk characterization.
3-48
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3.2 EXPOSURE ASSESSMENT
3.2.4 Exposure Parameters and Potential Dose Rate Models
This section contains information on models and parameter values for workplace and
population exposure estimates. First, more detailed data from the IPC Workplace Practices
Questionnaire are presented, then the exposure models and parameter values used in those
models are described.
Workplace Exposure Parameter Values
Data on the frequency and duration of activities indicate the amount of time a worker may
be exposed through workplace activities. Questionnaire data pertaining to various worker
activities follow.
Line Operation. The time per shift that an MHC line operates gives an indication of the
daily exposure duration associated with line operation. Time per shift varies by process type and
degree of automation. It is probably also influenced by the total amount of PWB processed at a
facility and MHC line capacity. Because limited data do not allow differentiation between MHC
line operation needs for the various process alternatives, the same period of time for line
operation is assumed for all process alternatives. This time, for all processes, ranges from one to
12 hours per shift, with an average of 6.8 hours per shift and a 90th percentile value of eight
hours per shift.
Chemical Bath Sampling. Table 3.11 presents questionnaire data pertaining to duration
and frequency of chemical bath sampling. These parameters are assumed to vary by MHC
technology, but not by equipment configuration (e.g., non-conveyorized or conveyorized).
Chemical Additions. Table 3.12 presents questionnaire and supplier data pertaining to
duration and frequency of chemical additions. Duration data indicate the amount of time a
worker may be exposed to the chemicals being added to the bath. Although duration data vary by
process and bath type, greater variation may be due to differences in facility operating procedures
than differences inherent to process alternatives. Therefore, the same duration is assumed for all
facilities, regardless of process, equipment, or bath type. Frequency of chemical additions was
determined from supplier-provided data, typically a supplier's Product Data Sheet, which
recommends a schedule for chemical additions based on time, amount of PWB (ssf) processed,
or bath concentrations determined through sampling. For the purposes of this assessment,
schedules based on time or ssf of PWB processed were used.
Chemical Bath Replacement. Table 3.13 presents questionnaire data pertaining to
duration of chemical bath replacement. Questionnaire data were combined regardless of process
configuration for replacement duration. Bath replacement frequency for conveyorized lines was
determined specifically for type of bath. The 90th percentile frequencies are presented in Table
3.14.
3-49
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3.2 EXPOSURE ASSESSMENT
Table 3.11 Duration and Frequency of Chemical Bath Sampling
Process Alternative
(number responding)9
Electroless Copper (32)
Carbon (2)
Conductive Polymer (1)
Graphite (4)
Non-Formaldehyde Electroless Copper (1)
Organic-Palladium (2)
Tin-Palladium (12)
Duration of
Sampling
(minutes)
Average*
0.44 - 5.4
2.0
1.0
1.0-5.5
1.0
1.5-2
1.2-4.0
90th
Percentile
3
2
1
10
1
2
2
frequency of
Sampling
(occnr./year)
Average*
217-996
220
100 - 460
213-255
50 - 260
230 - 490
210-660
90th
Percentile
720
220
414
260
260
250
520
Total
Responses
for
AH Baths
212
8
3
13
5
13
65
* Five facilities did not respond to this question.
b Range of averages for each bath type.
Table 3.12 Duration and Frequency of Chemical Additions
Facility Type
Electroless Copper
Carbon
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
All Facilities, regardless of process type
Duration of Chemical Additions
(minutes)"
Average
3.6-10°
2- 10C
2- 19°
2, regardless of bath type
20 - 25C
5-15c
8.6
90th Percentile
ND
ND
ND
ND
ND
ND
20
Frequency of
Chemical
Additions
(times/year)"
0.4 - 52°
1-58°
4-44c
1 1 - 52°
0.7- 12°
ND
* From EPC Workplace Practices Questionnaire and Performance Demonstration database.
b Based on supplier-provided information.
c Depending on bath type.
ND: Not Determined.
Table 3.13 Duration of Chemical Bath Replacement
Process Alternative
(number responding)
Electroless Copper (36)
Carbon (2)
Conductive Polymer (1)
Graphite (3)
Non-Formaldehyde Electroless Copper (1)
Organic-Palladium (2)
Tin-Palladium (13)
All Facilities
Duration (minutes)
Average*
41 - 147
15-180
60 - 240
18-240
30
30-360
31-110
78
90th Percentile
180
180
228
219
30
108
180
ND
Total Responses for AH Baths
205
8
3
10
5
13
75
350
* Range of averages for each bath type.
ND: Not Determined.
3-50
-------
3.2 EXPOSURE ASSESSMENT
Table 3.14 Freq
Process Alternative
Electroless Copper
Carbon
Conductive Polymer
Graphite
Organic-Palladium
Tin-Palladium
uency of Chemical Bath Replacement for Conveyorized Processes
Bath Type
Conditioner/Cleaner
Microetch
Predip
Catalyst
Cleaner
Conditioner
Microetch
Cleaner/Conditioner
Cleaner/Conditioner
Graphite
Conditioner
Microetch
Predip
Cleaner/Conditioner
Predip
Catalyst
90th Percentile
Frequency
(oecur./year)
24
50
24
1
30
30
20.5
13
56
7.3
32
1
230
141
151
1
Bath Type
Accelerator
Electroless
Copper
Acid Dip
Anti-Tarnish
Carbon Black
Microetch
Catalyst
Conductive
Polymer
Microetch
Conductor
Post-Dip
Accelerator
Microetch
Acid Dip
99th Pereentile
Frequency
(occur./year)
16
4
50
28
1
145
1
17
145
1
20
47
65
230
Conveyor Equipment Cleaning. For conveyor equipment cleaning, nine facilities
responded out of a total of 11 conveyorized systems. For these facilities:
• Duration of conveyor equipment cleaning ranged from 0.5 to 480 minutes, with an
average of 140 minutes and 90th percentile of 288 minutes.
• Frequency of conveyor equipment cleaning ranged from two to 260 times per year, with
an average of 55 times per year and 90th percentile of 92 times per year.
Bath Filter Replacement. Table 3.15 presents data on duration and frequency of bath
filter replacement. For filter replacement, depending on bath and process types, the average
duration ranges from one to 31 minutes and the average frequency ranges from 12 to 300 times
per year. The frequency data used for intake model parameters is process-specific. Again, the
duration for all facilities is assumed, regardless of process alternative or bath type.
Working in the Process Area. Table 3.16 presents questionnaire data pertaining to the
amount of time various types of workers spend working in the MHC process area. Frequency is
considered to be the days/year the MHC line is in operation (an average of 250 days/year and
90th percentile of 306 days/year).
3-51
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3.2 EXPOSURE ASSESSMENT
Table 3.15 Filter Replacement
Process Alternative
(number responding}3
Electroless Copper (20)
Carbon (2)
Conductive Polymer (1)
Graphite (4)
Non-Formaldehyde Electroless
Copper (1)
Organic-Palladium (2)
Tin-Palladium (3)
All Facilities
Duration
(minutes)
Average"
8-31
5
5-10
7-10
1-5
2-3.5
5-11
13
90tli
PereentUe
ND
ND
ND
ND
ND
ND
ND
20
Total
Responses
for
AH Baths
82
6
4
9
2
10
14
138
Frequency
(0ccur./year)
Average"
37 - 200
12-20
12.5-115
67 - 107
16.7
12-38
24 - 300
ND
90th
Percentile
100
20
74
103
17
50
74
ND
Total
Responses
for
All Baths
76
6
4
9
2
10
14
138
* Sixteen facilities did not respond to this question.
b Range of averages for each bath type.
ND: Not Determined.
Table 3.16 Duration of Working in the Process Area
Worker Type
Line Operators
Laboratory Technicians
Maintenance Workers
Supervisory Personnel
Wastewater Treatment Operators
Contract Workers
Other Employees
Range
(hours/shift)
3.3 - 10
0.1- 10
0.15- 10
0.23 - 10
0.1- 10
0.25
0.18-8
Average
(hours/shift)
7.8
3.9
3.1
4.7
4.4
0.25
3.4
90th Percentile
(hours/shift) ,
8
8
8
8
8
0.25
5.6
Workplace Exposure Models
The general models for calculating inhalation and dermal potential dose rates are
discussed below.
Daily Inhalation Exposures. The general model for inhalation exposure to workers is
from CEB (EPA, 1991a):
I = (Cm)(b)(h)
where:
I = daily inhalation potential dose rate (mg/day)
Cm = airborne concentration of substance (mg/m3) (note: this term is denoted "Cy" in
air modeling equation in Section 3.2.3)
b = inhalation rate (m3/hr)
h = duration (hr/day)
3-52
-------
3.2 EXPOSURE ASSESSMENT
Data for these parameters are in Table 3.17.
Table 3.17 Parameter Values for Daily Workplace Inhalation Exposures
Parameter
Cm
b
Units
mg/m3
. m3/hr
Value
Source of Data, Comments
Modeled from single or average bath concentrations
1.25
EPA, 1991a (data from NIOSH, 1976).
Duration (h)
Line
Operation
Working in
Process Area
hours/day
hours/day
8
8
From IPC Workplace Practices Questionnaire, 90th
percentile for hours of MHC line operation, all process
types (assuming hours/shift = hours/day).
From IPC Workplace Practices Questionnaire, 90th
percentile for hours/shift for first shift, all process types.
Daily Workplace Dermal Exposures. The general model for potential dose rate via
dermal exposure to workers is from CEB (EPA, 199la):
D = SQC
where:
D = dermal potential dose rate (mg/day)
S = surface area of contact (cm2)
Q = quantity typically remaining on skin (mg/cm2)
C = concentration of chemical (percent)
Because a line operator is expected to have dermal contact with the chemicals in a given
bath several times a day in the course of normal operations, the total time of contact combined
with a flux rate (rate of chemical absorption through the skin) is believed to give a more realistic
estimate of dermal exposure. The flux of a material through the skin is estimated in terms of mg
absorbed per cm2 per unit of time. Using flux of material through the skin, (based on EPA,
1992a) the equation is modified to:
D = (S)(C)(f)(h)(0.001)
where:
D = dermal potential dose rate (mg/day)
S = surface area of contact (cm2)
C = concentration of chemical (mg/L)
f = flux through skin (cm/hour)
h = duration (hours/day)
with a conversion factor of 0.001 L/cm3
This second equation was used for all workplace dermal exposure estimates.
Data for duration of contact (h) from the IPC Workplace Practices Questionnaire are
included in Table 3.18.
3-53
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3.2 EXPOSURE ASSESSMENT
Table 3.18 Parameter Values for Daily Workplace Dermal Exposures
Parameter
C
s
Flux
Through
Skin (f)
Unit$
%
cm2
cm/hr
Value
Source of Data, Comments
Range of reported values and average determined from publicly-available
chemistry data and from disclosed proprietary ingredient information (see
Section 2. 1 .4 and Appendix B).
1,300
Default for inorganics: 0.001
estimate for organics by:
log f = -2.72+0.71 log Kow -0.0061(MW)
(K,,w = octanol/water partition coefficient,
MW = molecular weight)
CEB Table 4-13, routine immersion,
2 hands, assuming gloves not worn.
EPA, 1992a.
Duration of Contact (h)
Line
Operation
Chemical
Bath
Replacement
Conveyor
Equipment
Cleaning
Filter
Replacement
Chemical
Bath
Sampling
hours/day
min/occur
min/occur
min/occur
min/occur
8
electroless copper
(19 baths)
non-formaldehyde
electroless copper
(17 baths)
organic-palladium
(12 baths)
tin-palladium
(14 baths)
carbon
conductive polymer
electroless copper
graphite
non-formaldehyde
electroless copper
organic-palladium
tin-palladium
0.42
0.47
0.67
0.57
180
228
180
219
30
108
180
288
20
carbon
conductive polymer
electroless copper
graphite
non-formaldehyde
electroless copper
organic-palladium
tin-palladium
2
1
5
10
1
2
2
90th percentile from IPC Workplace
Practices Questionnaire, hours of
MHC line operation, all process
types excluding conveyorized
processes.
Corrected for typical number of
baths in a process, including rinse
baths.
90th percentile from IPC Workplace
Practices Questionnaire.
90th percentile from IPC Workplace
Practices Questionnaire,
conveyorized lines.
90th percentile from IPC Workplace
Practices Questionnaire, all process
types.
90th percentile from IPC Workplace
Practices Questionnaire, excluding
automated sampling.
3-54
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3.2 EXPOSURE ASSESSMENT
Daily exposures are averaged over a lifetime (70 years) for carcinogens, and over the
exposure duration (e.g., 25 years working in a facility) for non-carcinogens4 using the following
equations. To estimate average daily doses for inhalation:
LADD = (I)(EF)(ED)/[(BW)(ATCAR)]
ADD = (I)(EF)(ED)/[(BW)(ATNC)]
where:
LADD = lifetime average daily dose (mg/kg-day) (for carcinogens)
ADD = average daily dose (mg/kg-day) (for non-carcinogens)
I = daily inhalation potential dose rate (mg/day)
EF = exposure frequency (days/year)
ED = exposure duration (years)
BW = body weight (kg)
ATCAR = averaging time for carcinogenic effects (days)
ATNC = averaging time for non-carcinogenic effects (days)
To estimate average daily doses from dermal contact:
LADD = (D)(EF)(ED)/[(BW)(ATCAR)]
ADD = (D)(EF)(ED)/[(BW)(ATNC)]
where:
D = dermal potential dose rate (mg/day)
Parameter values for estimating worker's potential dose rates are presented hi Table 3.19.
Results of estimating inhalation and dermal ADDs (and the inhalation LADD for formaldehyde)
are presented in Table 3.20 and Appendix E. Proprietary chemical results are not presented in
order to protect proprietary chemical identities. The frequency data for activities pertaining to
operating an MHC line could apply to more than one line worker, although they are assumed here
to apply to a single, typical line operator. For example, facilities reported from one to 18 line
operators working at one time, with an average of three line operators working the first shift.
Therefore, the frequency of various worker activities pertaining to a single line operator may be
overestimated by about a factor of three.
4 Different averaging times are used for characterizing risk for carcinogenic and non-carcinogenic effects. For
carcinogenic agents, because even a single incidence of exposure is assumed to have the potential to cause cancer
throughout an individual's lifetime, the length of exposure to that agent is averaged over a lifetime. An additional
factor is that the cancer latency period may extend beyond the period of working years before it is discernible. For
chemicals exhibiting non-cancer health effects from chronic (longer-term) exposure, where there is an exposure
threshold (a level below which effects are not expected to occur); only the time period when exposure is occurring is
assumed to be relevant and is used as the averaging time.
-------
3.2 EXPOSURE ASSESSMENT
Table 3.19 Parameter Values for Estimating Average Workplace Exposures
(for line operators)
Parameter
Units
Value
Source of Data, Comments
Exposure Frequency (EF): Inhalation Exposure
Line Operation &
Working in Process
Area
days/year
306
90th percentile, days/year MHC line
operates from IPC Workplace
Practices Questionnaire, all process
types (average is 250 days/year).
EF: Dermal Exposure
Line Operation
Chemical Bath
Replacement
Conveyor Equipment
Cleaning
Filter Replacement
Chemical Bath
Sampling
days/year
occur/year
occur/year
occur/year
occur/year
306
electroless copper
carbon
conductive polymer
graphite
organic-palladium
tin-palladium
1-50
1-145
1 - 20.5
7.3 - 145
1-230
1-230
92
electroless copper
carbon
conductive polymer
graphite
non-formaldehyde
electroless copper
organic-palladium
tin-palladium
electroless copper
carbon
conductive polymer
graphite
non-formaldehyde
electroless copper
organic-palladium
tin-palladium
100
20
74
103
17
50
74
720
220
414
260
260
250
520
90th percentile, days/year MHC line
operates from IPC Workplace
Practices Questionnaire, all process
types.
90th percentiles for conveyorized
processes from IPC Workplace
Practices Questionnaire (see Table
3.14).
90th percentile from IPC Workplace
Practices Questionnaire, for
conveyorized lines.
90th percentiles from IPC
Workplace Practices Questionnaire.
90th percentiles from IPC
Workplace Practices Questionnaire,
excluding automated sampling.
Parameters Pertaining to AH Workplace Exposures (for Line Operators)
Exposure Duration
(ED)
Body Weight (BW)
Averaging Time (AT)
"•TcAR
ATNC
years
kg
days
25
70
25,550
9,125
95th percentile for job tenure
(Bureau of Labor Statistics, 1990).
(Median tenure for U.S. males is 4
years; Bureau of Labor Statistics,
1997.)
Average for adults (EPA, 1991b).
70 yrs (average lifetime)*365 d/yr
25 yrs (ED)*365 d/yr
3-56
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3.2 EXPOSURE ASSESSMENT
Table 3.20 Estimated Average Daily Dose (ADD) for Workplace Exposure -
Inhalation and Dermal
Chemical*
ADB
(mg/kg-day)
Inhalation
Line
Operator
Bermal
Line
Operator
Laboratory
Technician
Electroless Copper, non-conveyorized
Ammonium Chloride
Benzotriazole
Boric Acid
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Dimethylaminoborane
Dimethylformamide
Ethanolamine
2-Ethoxyethanol
Ethylene Glycol
Ethylenediaminetetraacetic Acid (EDTA)
Fluoroboric Acid
Formaldehyde
Formaldehyde (LADD)b
Formic Acid
Hydrochloric Acid
Hydrogen Peroxide
Hydroxyacetic Acid
Isopropyl Alcohol; or 2-Propanol
Magnesium Carbonate
Methanol
m-Nitrobenzene Sulfonic Acid
p-Toluene Sulfonic Acid
Palladium
Peroxymonosulfuric Acid
Potassium Bisulfate
Potassium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium Sulfate
Potassium-Sodium Tartrate
Sodium Bisulfate
Sodium Carbonate
Sodium Chlorite
NA
6.64e-04
9.156-04
4.05e-04
4.45e-04
1.04e-02
7.58e-03
5.31e-02
7.79e+00
1.78e-02
2.74e-03
1.18e-02
7.36e-02
2,63e-02
1.88e-01
2.91e-05
8.87e-04
1.68e-04
2.81e+00
5.35e-05
1.24e+00
4.90e-06
NA
NA
1.15e-03
6.15e-04
1.35e-05
1.25e-05
4.37e-04
8.56e-04
1.90e-03
NA
3.03e-06
NA
8.4e-02
2.5e-03
3.3e-02
4.4e-02
4.9e-02
3.9e-03
l.le-03
l.Oe-02
1.4e-01
2.5e-03
1.7e-05
3.9e-01
l.le-02
NA
3.5e-02
9.0e-01
1.3e-01
2.4e-02
3.1e-02
7.8e-03
l.le-02
8.8e-07
4.0e-03
2.4e-03
1.7e-01
9.0e-02
1.5e-03
5.4e-03
6.4e-02
1.3e-01
2.1e-01
4.6e-01
3.3e-04
3.0e-02
2.1e-03
6.1e-05
8.0e-04
l.le-03
1.2e-03
9.6e-05
2.8e-05
2.56-04
3.4e-03
6.06-05
4.2e-07
9.6e-03
2.6e-04
NA
8.5e-04
2.2e-02
3.2e-03
5.9e-04
7.7e-04
1.9e-04
2.8e-04
2.2e-08
9.8e-05
5.8e-05
4.2e-03
2.2e-03
3.6e-05
1.3e-04
1.6e-03
3.1e-03
5.0e-03
l.le-02
8.03-06
7.2e-04
3-57
-------
3.2 EXPOSURE ASSESSMENT
Chemical"
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Sulfate
Stannous Chloride
Sulfuric Acid
Tartaric Acid
Triethanolamine; or 2,2',2"-Nitrilotris Ethanol
AD1>
(mg/kg-day)
Inhalation
Line
Operator
1.40e-05
6.30e-04
NA
NA
NA
6.67e-03
6.24e-05
NA
Dermal
Une
Operator
1.5e-03
8.5e-02
5.6e-02
8.3e-02
6.7e-02
1.2e+00
5.7e-05
3.5e-03
Laboratory
Technician
3.7e-05
2.1e-03
1.4e-03
2.0e-03
1.6e-03
2.9e-02
1.4e-06
8.5e-05
Electroless Copper, conveyorized
Ammonium Chloride
Benzotriazole
Boric Acid
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Dimethylaminoborane
Dimethylformamide
Ethanolamine
2-Ethoxyethanol
Ethylene Glycol
Ethylenediaminetetraacetic Acid (EDTA)
Fluoroboric Acid
Formaldehyde
Formic Acid
Hydrochloric Acid
Hydrogen Peroxide
Hydroxyacetic Acid
Isopropyl Alcohol; or 2-Propanol
Magnesium Carbonate
Methanol
m-Nitrobenzene Sulfonic Acid
p-Toluene Sulfonic Acid
Palladium
Peroxymonosulfuric Acid
Potassium Bisulfate
Potassium Cyanide
Potassium Hydroxide
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
2.1e-02
6.3e-04
9.2e-03
9.8e-03
l.le-02
l.le-03
2.8e-04
2.5e-03
3.5e-02
6.5e-04
3.8e-06
9.4e-02
2.4e-03
8.6e-03
2.1e-01
3.6e-02
6.0e-03
7.8e-03
2.2e-03
2.6e-03
2.2e-07
9.9e-04
5.2e-04
4.7e-02
2.5e-02
3.3e-04
1.4e-03
2.1e-03
6.1e-05
8.0e-04
l.le-03
1.2e-03
9.6e-05
2.8e-05
2.5e-04
3.4e-03
6.0e-05
4.2e-07
9.6e-03
2.6e-04
8.5e-04
2.2e-02
3.2e-03
5.9e-04
7.7e-04
1.9e-04
2.8e-04
2.2e-08
9.8e-05
5.8e-05
4.2e-03
2.2e-03
3.6e-05
1.3e-04
3-58
-------
3.2 EXPOSURE ASSESSMENT
Chemical"
Potassium Persulfate
Potassium Sulfate
Potassium-Sodium Tartrate
Sodium Bisulfate
Sodium Carbonate
Sodium Chlorite
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Sulfate
Stannous Chloride
Sulfuric Acid
Tartaric Acid
Triethanolamine; or 2,2',2"-Nitrilotris Ethanol
ADI>
{mg/kg-day)
Inhalation
Line
Operator
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Dermal
Line
Operator
1.8e-02
3.5e-02
4.6e-02
LOe-01
7.3e-05
7.0e-03
3.4e-04
1.9e-02
1.3e-02
1.8e-02
1.5e-02
3.2e-01
1.3e-05
8.6e-04
Laboratory
Technician
1.6e-03
3.1e-03
5.0e-03
l.le-02
8.0e-06
7.2e-04
3.7e-05
2.1e-03
1.4e-03
2.0e-03
1.6e-03
2.9e-02
1.4e-06
8.5e-05
Carbon, conveyorized
Copper Sulfate; or Cupric Sulfate
Ethanolamine
Potassium Hydroxide
Sodium Persulfate
Sulfuric Acid
NA
NA
NA
NA
NA
1.7e-02
9.6e-03
7.3e-02
7.0e-01
6.4e-03
1.4e-04
1.3e-04
1.2e-03
5.7e-03
5.3e-05
Conductive Polymer, conveyorized
IH-Pyrrole
Peroxymonosulfuric Acid; or Potassium Peroxymonosulfate
Phosphoric Acid
Sodium Carbonate
Sodium Hydroxide
Sulfuric Acid
NA
NA
NA
NA
NA
NA
2.6e-02
7.0e-01
l.Oe-01
2.5e-02
2.7e-03
1.4e-02
3.3e-04
8.8e-03
1.3e-03
3.3e-04
4.0e-05
1.8e-03
Graphite, conveyorized
Ammonia
Copper Sulfate; or Cupric Sulfate
Ethanolamine
Graphite
Peroxymonosulfuric Acid; or Potassium Peroxymonosulfate
Potassium Carbonate
Sodium Persulfate
Sulfuric Acid
NA
NA
NA
NA
NA
NA
NA
NA
4.2e-03
l.le-02
5.3e-03
9.8e-02
1.2e-01
2.1e-02
2.4e-01
2.4e-01
3.3e-04
4.5e-04
3.2e-04
7.7e-03
5.1e-03
1.3e-03
9.7e-03
l.Oe-02
3-59
-------
3.2 EXPOSURE ASSESSMENT
ChemieaP
AD0
(mg/kg-day)
Inhalation
Line
Operator
Dermal
Line
Operator
Laboratory
Technician
Non-Formaldehyde Electroless Copper, non-conveyorized
Copper Sulfate; or Cupric Sulfate •
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or 2-Propanol
Potassium Hydroxide
Potassium Persulfate
Sodium Chlorite
Sodium Hydroxide
Stannous Chloride
Sulfuric Acid
1.47e-03
NA
5.01e-04
3.93e-01
7.99e-06
3.04e-04
NA
9.31e-06
NA
7.94e-04
1.7e-01
2.2e-02
1.2e-01
1.3e-02
2.2e-03
7.2e-02
3.3e-02
2.2e-03
6.9e-02
1.7e-01
2.7e-04
3.4e-05
1.9e-04
2.1e-05
3.5e-06
1.1 e-04
5.2e-05
3.5e-06
1.1 e-04
2.6e-04
Organic-Palladium, non-conveyorized
Hydrochloric Acid
Sodium Bisulfate
Sodium Carbonate
Sodium Hypophosphite
Sodium Persulfate
Trisodium Citrate 5.5-Hydrate; or Sodium Citrate
NA
NA
NA
NA
NA
NA
6.4e-02
7.8e-01
2.3e-01
3.2e-02
7.8e-01
6.7e-03
2.2e-04
2.7e-03
7.8e-04
1.1 e-04
2.7e-03
2.3e-05
Organic-Palladium, conveyorized
Hydrochloric Acid
Sodium Bisulfate
Sodium Carbonate
Sodium Hypophosphite
Sodium Persulfate
Trisodium Citrate 5.5-Hydrate; or Sodium Citrate
NA
NA
NA
NA
NA •
NA
1.8e-02
1.5e-01
4.8e-02
6.1e-03
1.5e-01
1.4e-03
2.2e-04
2.6e-03
7.8e-04
1.1 e-04
2.6e-03
2.3e-05
Tin-Palladium, non-conveyorized
1,3-Benzenediol
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Ethanolamine
Fluoroboric Acid
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or 2-Propanol
Lithium Hydroxide
Palladium
NA
NA
3.95e-04
1.07e-01
9.45e-03
NA
5.20e-04
1.58e+00
NA
NA
9.7e-03
2.3e-02
1.3e-01
2.7e-02
1.7e-01.
2.9e-01
1.6e-01
1.6e-02
1.8e-01
8.5e-03
9.7e-05
2.3e-04
1.2e-03
2.7e-04
1.7e-03
2.9e-03
1.5e-03
1.6e-04
1.8e-03
8.5e-05
3-60
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3.2 EXPOSURE ASSESSMENT
Chemical"
Palladium Chloride
Potassium Carbonate
Sodium Bisulfate
Sodium Chloride
Sodium Hydroxide
Sodium Persulfate
Stannous Chloride
Sulfuric Acid
Triethanolamine; or 2,2',2"-Nitrilotris Ethanol
Vanillin
ADI>
{mg/kg-day)
Inhalation
Line
Operator
NA
NA
NA
NA
NA
4.49e-03
NA
6.21e-04
NA
4.33e-04
Dermal
Line
Operator
5.3e-03
2.9e+00
7.9e-01
9.0e+00
2.6e-01
1.3e+00
2.8e-01
1.9e+00
2.4e-03
3.0e-03
Laboratory
Technician
5.3e-05
2.9e-02
7.9e-03
9.0e-02
2.6e-03
1.3e-02
2.8e-03
1.9e-02
2.4e-05
3.0e-05
Tin-Palladium, conveyorized
1,3-Benzenediol
Copper (I) Chloride
Copper Sulfate; or Cupric Sulfate
Ethanolamine
Fluoroboric Acid
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or 2-Propanol
Lithium Hydroxide
Palladium
Palladium Chloride
Potassium Carbonate
Sodium Bisulfate
Sodium Chloride
Sodium Hydroxide
Sodium Persulfate
Stannous Chloride
Sulfuric Acid
Triethanolamine; or 2,2',2"-Nitrilotris Ethanol
Vanillin
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
2.7e-03
8.1e-03
4.9e-02
1.2e-02
6.0e-02
l.le-01
6.1e-02
8.4e-03
6.5e-02
2.4e-03
1.5e-03
l.Oe+00
3.3e-01
3.3e+00
9.2e-02
5.2e-01
7.9e-02
1.2e+00
1.2e-03
8.4e-04
9.7e-05
2.3e-04
1.2e-03
2.7e-04
1.7e-03
2.9e-03
1.6e-03
1.6e-04
1.8e-03
8.5e-05
5.3e-05
2.9e-02
7.9e-03
9.0e-02
2.6e-03
1.3e-02
2.8e-03
1.9e-02
2.4e-05
3.0e-05
Proprietary chemical results are not presented hi order to protect proprietary chemical identities.
b LADD is calculated using a carcinogen averaging time (ATCAR) of 70 years.
Note: The numeric format used in these tables is a form of scientific notation, where the "e" replaces the
" x 10"" in scientific notation. Scientific notation is typically used to present very large or very small numbers. For
example, 1.2e-04 is the same as 1.2 x 10"4, which is the same as 0.00012 in common decimal notation.
NA: Not Applicable. A number was not calculated because the chemical's vapor pressure is below the 1 x 10"3 torr
cutoff and is not used in any sparged bath. Inhalation exposures are therefore expected to be negligible. LADDs
were not calculated for dermal exposure.
3-61
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3.2 EXPOSURE ASSESSMENT
Population Exposure
The equation for estimating ADDs from inhalation for a person residing near a facility is:
LADD = (Ca)(IR)(EF)(ED)/[(BW)(ATCAR)]
ADD = (Ca)(IR)(EF)(ED)/[(BW)(ATNC)]
where:
LADD = lifetime average daily dose (mg/kg-day) (for carcinogens)
ADD = average daily dose (mg/kg-day) (for non-carcinogens)
Ca = chemical concentration in air (mg/m3) (from air dispersion modeling, described
in Section 3.2.3)
IR = inhalation rate (m3/day)
EF = exposure frequency (day/yr)
ED = exposure duration (years)
BW = average body weight (kg)
ATCAR = averaging time for carcinogenic effects (days)
ATNC = averaging time for non-carcinogenic chronic effects (days)
Table 3.21 presents values used for these parameters.
Table 3.21 Parameter Values for Estimating Nearby Residential Inhalation Exposure
Parameter
Ca
IR
EF
ED
BW
AT
ATcAR
ATNc
Units
mg/m3
mVday
days/year
years
kg
days
Value
Source of Bataf Comments
Modeled, varies by chemical and process type.
15
350
30
70
25,550
10,950
Total home exposures for adults based on activity patterns and
inhalation rates (EPA, 1997).
Assumes 2 weeks per year spent away from home (EPA, 1991b).
National upper 90th percentile at one residence (EPA, 1990).
Average value for adults (EPA, 1991b).
70 yrs*365 days/year
ED * 365 days/year
Results for general population inhalation exposure are presented in Table 3.22 and
Appendix E. Proprietary chemical results are not presented in order to protect proprietary
chemical identities.
3-62
-------
3.2 EXPOSURE ASSESSMENT
Table 3.22 Estimated Average Daily Dose (ADD) for General Population Inhalation
Exposure
Chemical*
ABB
(mg/kg-day)
Electroless Copper, non-conveyorized
2-Ethoxyethanol
Formaldehyde
Formaldehyde (LADD)b
[sopropyl Alcohol; or 2-Propanol
Methanol
6.5e-04
7.4e-06
2.6e-06
2.4e-04
l.Oe-04
Electroless Copper, conveyorized
2-Ethoxyethanol
Formaldehyde
Formaldehyde (LADD)b
Formic Acid
Isopropyl Alcohol; or 2-Propanol
Methanol
7.0e-04
2.0e-05
7.0e-06
3.5e-05
4.6e-04
1.9e-04
Non-Formaldehyde Electroless Copper, non-conveyorized
Isopropyl Alcohol; or 2-Propanol
3.3e-05
Tin-Palladium, non-conveyorized
Isopropyl Alcohol; or 2-Propanol
1.3e-04
Tin-Palladium, conveyorized
Ethanolamine
Isopropyl Alcohol; or 2-Propanol
2.3e-05
l.Oe-04
Only those chemicals with an emission rate at least 23 kg/year (44 mg/min), plus formaldehyde, are listed. Carbon,
conductive polymer, graphite, and organic-palladium had no modeled emission rates above this cut-off. Also,
proprietary chemical results are not presented in order to protect proprietary chemical identities.
b LADD is calculated using a carcinogen averaging time (ATCAR) of 70 years.
Note: The numeric format used in these tables is a form of scientific notation, where the "e" replaces the " x 10X" in
scientific notation. Scientific notation is typically used to present very large or very small numbers. For example,
1.2e-04 is the same as 1.2 x 10"4, which is the same as 0.00012 in common decimal notation.
3.2.5 Uncertainty and Variability
Because of both the uncertainty inherent in the parameters and assumptions used in
estimating exposure, and the variability that is possible within a population, there is no one
number that can be used to describe exposure. In addition to data and modeling limitations,
discussed in Sections 3.2.3, sources of uncertainty in assessing exposure include the following:
• Accuracy of the description of exposure setting: how well the model facility used in the
assessment characterizes an actual facility; the likelihood of exposure pathways actually
occurring (scenario uncertainty).
3-63
-------
3.2 EXPOSURE ASSESSMENT
• Missing data and limitations of workplace practices data: this includes possible effects of
any chemicals that may not have been included (e.g., minor ingredients in the
formulations and proprietary chemical identities not disclosed by suppliers5); possible
effects of side reactions in the baths, which were not considered; and questionnaire data
with limited facility responses.
• Estimating exposure levels from averaged data and modeling in the absence of measured,
site-specific data.
• Data limitations in the Source Release Assessment: releases to surface water and land
could not be characterized quantitatively, as discussed in Section 3.1.
• Chemical fate and transport model applicability and assumptions: how well the models
and assumptions represent the situation being assessed and the extent to which the models
have been validated or verified (model uncertainty).
• Parameter value uncertainty, including measurement error, sampling error, parameter
variability, and professional judgement.
• Uncertainty in combining pathways for an exposed individual.
A method typically used to provide information about the position an exposure estimate
has in the distribution of possible outcomes is the use of exposure (or risk) descriptors. EPA's
Guidelines for Exposure Assessment (EPA, 1992b) provides guidance on the use of risk
descriptors, which include the following:
• High-end; approximately the 90th percentile of the actual (measured or estimated)
distribution. This is a plausible estimate of individual risk for those persons at the upper
end of the exposure distribution, and is not higher than the individual in the population
who has the highest exposure.
• Central tendency: either an average estimate (based on average values for the exposure
parameters) or a median estimate (based on 50th percentile or geometric mean values).
• What-if: represents an exposure estimate based on postulated questions (e.g., what if the
air ventilation rates were ... ), in this case, making assumptions based on limited data so
that the distribution is unknown. If any part of the exposure assessment qualifies as a
"what-if' descriptor, then the entire exposure assessment is considered "what-if."
This exposure assessment uses whenever possible a combination of central tendency
(either an average or median estimate) and high-end (90th percentile)6 assumptions, as would be
used for an overall high-end exposure estimate. The 90th percentile is used for:
5 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary chemical
ingredients to the project. Atotech provided information on one proprietary ingredient. W.R. Grace was making
arrangements to transfer information on proprietary chemical ingredients in the conductive ink technology when it
was determined that this information was no longer necessary because risk from the conductive ink technology could
not be characterized. The other suppliers participating in the project (Enthone-OMI, MacDermid, and Shipley)
declined to provide proprietary information on their MHC technologies. The absence of information on proprietary
chemical ingredients is a significant source of uncertainty in the risk characterization. Risk information for
proprietary ingredients is presented in this CTSA, but chemical identities, concentrations, and chemical properties
are not listed.
6 For exposure data from the IPC Workplace Practices Questionnaire, this means that 90 percent of the facilities
reported a lower value, and ten percent reported a higher value.
__ ,
-------
3.2 EXPOSURE ASSESSMENT
Hours per day of workplace exposure.
Exposure frequency (days per year).
Exposure duration in years (90th percentile for occupational and 95th percentile for
residential exposures).
The time and frequency of chemical bath and filter replacements, conveyor equipment
cleaning and chemical bath sampling (minutes per occurrence and number of occurrences
per year), and estimated workplace air concentrations.
Average values are used for:
Body weight.
Concentration of chemical in bath.
The number of baths in a given process.
However, because some data, especially pertaining to bath concentrations and inhalation
exposure are limited, and this exposure assessment does not apply to a specific facility, the entire
exposure assessment should be considered "what-if."
3.2.6 Summary
This exposure assessment uses a "model facility" approach, with the goal of comparing
the exposures and health risks of one MHC technology to the exposures and risks associated with
switching to another technology. As much as possible, reasonable and consistent assumptions
are used across alternatives. Data to characterize the model facility and exposure patterns for
each MHC technology were aggregated from a number of sources, including PWB shops in the
U.S. and abroad, supplier data, and input from PWB manufacturers at project meetings. Thus,
the model facility is not entirely representative of any one facility, and actual exposure (and risk)
could vary substantially, depending on site-specific operating conditions and other factors.
Chemical exposures to PWB workers and the general population from day-to-day MHC
line operations were estimated by combining information gathered from industry (IPC Workplace
Practices Questionnaire, MSDSs, and other available information) with standard EPA exposure
assumptions for inhalation rate, surface area of dermal contact and other parameters, as discussed
in the exposure assessment. The pathways identified for potential exposure from MHC process
baths were inhalation and dermal contact for workers, and inhalation contact only for the general
populace living near a PWB facility.
Environmental releases to surface water were not quantified due to a lack of data and the
limited scope of this assessment. Chemical constituents and concentrations in wastewater could
not be adequately characterized (see Section 3.2.3). Nor were the possible impacts of short-term
exposures to high levels of hazardous chemicals addressed, such as those that could occur from
chemical fires, spills, or other periodic releases.
Inhalation exposure could occur by breathing air containing vapor or aerosol-phase
chemicals from the MHC process line. Inhalation exposures to workers are estimated only for
non-conveyorized lines; inhalation exposure to workers from conveyorized MHC lines was
assumed to be negligible because the lines are typically enclosed and vented to the outside.
3-65
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3.2 EXPOSURE ASSESSMENT
The daily intake for inhalation exposure to workers was calculated by first modeling
chemical emissions from MHC baths with three air-transport mechanisms: liquid surface
diffusion (desorption), bubble desorption, and aerosol generation and ejection. This chemical
emission rate was combined with information from the IPC Workplace Practices Questionnaire
regarding process room size and air turnover rate to estimate an average indoor air concentration
for the process area. General room ventilation was assumed, although the majority of shops have
local ventilation on chemical tanks. An uncertainty and sensitivity analysis of the air transport
models suggests that the air turnover (ventilation) rate assumption greatly influences the
estimated air concentration in the process area because of its large variability.
Inhalation exposure to the human population surrounding PWB plants was estimated
using the Industrial Source Complex - Long Term (ISCLT) air dispersion model. The modeled
air concentrations of each contaminant were determined at 100 meters radially from a PWB
facility, and the highest estimated air concentration was used. This model estimates air
concentration from the process bath emission rates. These emissions were assumed to be vented
to the ambient environment at the rate emitted from the baths, for all process alternatives.
Inhalation exposures estimated for the public living 100 meters away from a PWB facility were
very low (approximately 10,000 times lower than occupational exposures).
Dermal exposure could occur when skin comes in contact with the bath solution while
dipping boards, adding replacement chemicals, etc. Although the data suggest that most MHC
line operators do wear gloves, it was assumed in this evaluation that workers do not wear gloves
to account for the fraction that do not. Otherwise, dermal exposure is expected to be negligible.
For dermal exposure, the concentration of chemical in the bath and duration of contact for
workers was obtained from the IPC Workplace Practices Questionnaire information. A
permeability coefficient (rate of penetration through skin) was estimated for organics and a
default rate assumption was used for inorganics. Another source of uncertainty in dermal
modeling lies with the assumed duration of contact. The worker is assumed to have potential
dermal contact for the entire time spent in the MHC area, divided equally among the baths. (This
does not mean that a worker has both hands immersed in a bath for that entire time; but that the
skin is in contact with bath solution, i.e., the hands may remain wet from contact.) This
assumption may result in an overestimate of dermal exposure.
Assumptions and parameter values used in these equations are presented throughout this
section. Complete results of the exposure calculations are presented in Appendix E, except
proprietary chemical results are not presented in order to protect proprietary chemical identities.
Exposure estimates are based on a combination of high end (90th percentile)7 and average values,
as would be used for a high-end exposure estimate. The 90th percentile was used for hours per
day of workplace exposure, exposure frequency (days per year), exposure duration in years (90th
percentile for occupational and 95th percentile for residential exposures), and the time and
frequency of chemical bath and filter replacements, conveyor equipment cleaning and chemical
bath sampling (minutes per occurrence and number of occurrences per year) and estimated
workplace ah- concentrations. The average value was used for body weight, concentration of
7 For exposure data from the IPC Workplace Practices Questionnaire, this means that 90 percent of the facilities
reported a lower value, and ten percent reported a higher value.
_
-------
3.2 EXPOSURE ASSESSMENT
chemical in bath, and the number of baths in a given process. However, because some data,
especially pertaining to bath concentrations and inhalation exposure are limited, and this
exposure assessment does not apply to a specific facility, the entire exposure assessment should
be considered "what-if."
3-67
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
This section presents a summary of the human health and ecological hazards data that
were used in the risk characterization.8 This information is summarized from toxicity profiles
prepared for non-proprietary chemicals identified as constituents in the baths for the MHC
technologies evaluated. Table 3.23 lists these chemicals and identifies the MHC process or
processes in which these chemicals are used. The electroless copper process is the predominant
method now used in MHC. Section 2.1.4 includes more detailed information on bath
constituents and concentrations. Throughout this section, toxicity data for proprietary chemicals
are not presented in order to protect proprietary chemical identities.
Table 3.23 Known Use Cluster Chemicals and Associated MHC Processes
Chemical List
2-Ethoxyethanol
1,3-Benzenediol
IH-Pyrrole
2-Butoxyethanol Acetate;
Butylcellusolve Acetate
Ammonia
Ammonium Chloride
Benzotriazole
Boric Acid
Carbon Black
Copper (I) Chloride; Copper
Copper Sulfate; or
Cupric Sulfate
Diethylene Glycol n-Butyl
Ether
Diethylene Glycol Ethyl Ether
Diethylene Glycol Methyl
Ether
3imethylaminoborane
Dimethylformamide
sthanolamine;
Vlonoethanolamine;
2-Aminoethanol
ithylene Glycol
ithylenediaminetetraacetic
Acid (EDTA)
Jluoroboric Acid; Sodium
iifluoride
formaldehyde
Formic Acid
Electroless
Copper
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Carbon
•
•
•
•
Conductive
Ink
•
•
•
•
•
•
Conductive
Polymer
•
Graphite
•
•
•
No»-
FormaMehyde
Electroless
Copper
•
Ourganic-
Pafladium
Titt-
Palladium
•
•
•
•
•
Risk was not characterized for the conductive ink technology but human health and ecological hazards
data are presented here.
3-68
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Ost
Graphite
Hydrochloric Acid
sopropyl Alcohol; :
2-Propanol
Lithium Hydroxide
tn-Nitrobenzene Sulfonic
Acid; Sodium
m-Nitrobenzenesulfonate
Magnesium Carbonate
Methanol
p-Toluene Sulfonic Acid;
Palladium
Palladium Chloride
Peroxymonosulfuric Acid;
Phenol-Formaldehyde
Copolymer
Phosphoric Acid
Potassium Bisulfate
Potassium Carbonate
Potassium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium Sulfate
Potassium-Sodium Tartrate
Silver
Sodium Bisulfate
Sodium Carbonate
Sodium Chloride
Sodium Chlorite
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Persulfate
Sodium Sulfate
Stannous Chloride;
Tin (II) Chloride
Sulfuric Acid
Tartaric Acid
rriethanolamine; or
2,2', 2" -NitrilotrisEthanol
Slectroless
Copper
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
-arton
•
•
•
•
^ondaetive
Ink
•
•
•
•
•
^ondwetive
Polymer
•
•
•
•
•
Sraphite
•
•
•
•
•
Non-
?ormaldehyde
Etectroless
Copper
•
•
•
•
•
•
•
•
•
Organic-
alladium
•
•
•
•
Ttft-
'alladium
•
•
•
•
•
•
•
•
•
•
•
•
•
•
3-69
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical List
Irisodium Citrate 5.5-
Hydrate; Sodium Citrate
Vanillin
Proprietary Chemicals
[no. known for alternative)
Eleetroless
Copper
12
Carbon
Conductive
Ink
Conductive
Polymer
Graphite
5
Non-
Formaldehyde
Efectroless
Copper
Organic-
Palladium
•
1
Tte-
Palladium
•
5
3.3.1 Carcinogenicity
Table 3.24 summarizes the available information pertaining to carcinogenicity for the
MHC chemicals, including classifications describing evidence of chemical carcinogenicity. Due
to the large number of chemicals in commerce, including approximately 15,000 non-polymeric
chemicals produced in significant amounts (i.e., > 10,000 Ibs/year), many chemicals have not yet
been tested or assigned carcinogenicity classifications. The classifications referenced in this risk
assessment are defined below:
EPA Weight-of-Evidence Classification: In assessing the carcinogenic potential of a
chemical, EPA classifies the chemical into one of the following groups, according to the weight-
of-evidence from epidemiologic, animal and other supporting data, such as genotoxicity test
results:
• Group A: Human Carcinogen (sufficient evidence of carcinogenicity in humans).
• Group B: Probable Human Carcinogen (Bl - limited evidence of carcinogenicity in
humans; B2 - sufficient evidence of carcinogenicity in animals with inadequate or lack of
evidence in humans).
• Group C: Possible Human Carcinogen (limited evidence of carcinogenicity in animals
and inadequate or lack of human data).
• Group D: Not Classifiable as to Human Carcinogenicity (inadequate or no evidence).
• Group E: Evidence of Non-Carcinogenicity for Humans (no evidence of carcinogenicity
in adequate studies).
EPA has proposed a revision of its guidelines that would eliminate the above discrete
categories while providing a more descriptive classification.9
International Agency for Research on Cancer (IARC) Classification: This is a similar
weight-of-evidence method for evaluating potential human carcinogenicity based on human date,
animal data, and other supporting data. A summary of the IARC carcinogenicity classification
system includes:
9 The "Proposed Guidelines for Carcinogen Risk Assessment" (EPA, 1996a) propose use of weight-of-
evidence descriptors, such as "Likely" or "Known," "Cannot be determined," and "Not likely," in combination with
a hazard narrative, to characterize a chemical's human carcinogenic potential; rather than the classification system
described above.
3-70
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
• Group 1: Carcinogenic to humans.
• Group 2A: Probably carcinogenic to humans.
• Group 2B: Possibly carcinogenic to humans.
• Group 3: Not classifiable as to human carcinogenicity.
• Group 4: Probably not carcinogenic to humans.
Both of these classification schemes represent judgements regarding the likelihood of
human carcinogenicity. Table 3.24 lists all MHC chemicals which have been classified by EPA
or IARC. The National Toxicology Program (NTP) is an additional source used to classify
chemicals, but its classifications are based only on animal data from NTP studies.
Table 3.24 Available Carcinogenicity Information
Chemical Name"
Formaldehyde
Carbon Black
Dimethylformamide
1,3-Benzenediol
Hydrochloric Acid
Hydrogen Peroxide
Copper (I) Chloride
Copper (II) Chloride
Palladium; Palladium Chloride
Sodium Sulfate
Triethanolamine; or 2,2',2"-
Nitrilotris Ethanol
Cyclic Ether6
Alkyl Oxide8
Trisodium Acetate Amine Bj
Cancer Slope Factor
(mg/kg-dayy1
0.046b
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
not reported11
not reported11
ND
Comments/Classifications
EPA Group Bl (EPA, 1995b)c;
IARC Group 2A (IARC, 1995)°
IARC Group 2B (IARC, 1996)d
IARC Group 2B (IARC, 1989)d
IARC Group 3 (IARC, 1987)e
IARC Group 3 (HSDB, 1995)e
IARC Group 3 (IARC, 1987)e
EPA Group D (EPA, 1995c)f
EPA Group D (EPA, 1995c)f
No classification; rats developed respiratory
tumors and leukemia at 5 ppm in water
(Schroeder & Mitchener, 1971)
No classification; "equivocal evidence" of
tumorigenicity in mice (RTECS, 1995)
No classification; equivocal carcinogenic
evidence in animals (NTP, 1994)
Possible/probable human carcinogen'
Probable human carcinogen1
Possible human carcinogen1
Only those chemicals with available data or classifications are listed.
b Unit risk units were converted from 1.3 x 10~5 jUg/m3 ~l to slope factor units of (mg/kg-day)"1 using 20 mVday
inhalation (breathing) rate and 70 kg body weight.
c EPA Group B: Probable Human Carcinogen (Bl - limited evidence of carcinogenicity in humans); IARC Group
2A: Possibly carcinogenic to humans.
d IARC Group 2B: Possibly carcinogenic to humans.
e IARC Group 3: Not classifiable as to human carcinogenicity.
f EPA Group D: Not classifiable as to human carcinogenicity (inadequate or no evidence).
B In graphite and electroless copper technologies.
h Cancer slope factors are available but not reported in order to protect proprietary chemical identities.
1 Specific EPA and/or IARC groups not reported in order to protect proprietary chemical identities.
J In electroless copper technology.
ND: No Data. A cancer slope factor has not been determined for this chemical.
3-71
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
For carcinogenic effects, there is presumably no level of exposure that does not pose a
small, but finite, probability of causing a response. This type of mechanism is referred to as
"non-threshold." When the available data are sufficient for quantification, EPA develops an
estimate of the chemical's carcinogenic potency expressed as a "slope factor." The slope factor
(q,*) is a measure of an individual's excess risk or increased likelihood of developing cancer if
exposed to a chemical (expressed in units of [mg/kg-day]"1). More specifically, qj* is an
approximation of the upper bound of the slope of the dose-response curve using the linearized
multistage procedure at low doses. "Unit risk" is an equivalent measure of potency for air or
drinking water concentrations and is expressed as the upper bound excess lifetime cancer risk per
yUg/m3 in air, or as risk per //g/L in water, for continuous lifetime exposures. (Unit risk is simply
a transformation of slope factor into the appropriate scale.) Slope factors and unit risks can be
viewed as quantitatively derived judgements of the magnitude of carcinogenic effect. These
estimates will continue to be used whether the current EPA weight-of-evidence guidelines are
retained or the new proposals are adopted. Their derivation, however, may change for future
evaluations.
EPA risk characterization methods require a slope factor or unit risk to quantify the upper
bound excess cancer risk from exposure to a known or suspected carcinogen. Therefore,
formaldehyde is the only non-proprietary chemical for which cancer risk was characterized (see
Section 3.4, Risk Characterization).
3.3.2 Chronic Effects (Other than Carcinogenicity)
Adverse effects other than cancer and gene mutations are generally assumed to have a
dose or exposure threshold. Therefore, a different approach is needed to evaluate toxic potency
and risk for these "systemic effects." Systemic toxicity means an adverse effect on any organ
system following absorption and distribution of a toxicant to a site in the body distant from the
toxicant's entry point. A reference dose (RfD) is an estimate (with uncertainty spanning perhaps
an order of magnitude) of the daily exposure through ingestion to the human population
(including sensitive subgroups) that is likely to be without an appreciable risk of deleterious non-
cancer effects during a lifetime (in mg/kg-day). Similarly, a reference concentration (RfC) is an
estimate (with uncertainty spanning perhaps an order of magnitude) of the daily inhalation
exposure to the human population (including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious non-cancer effects during a lifetime (in mg/m3) (Barnes and
Dourson, 1988). RfDs and RfCs can also be derived from developmental toxicity studies.
However, this was not the case for any of the MHC chemicals evaluated. RfDs and RfCs are
derived from EPA peer-reviewed study results (for values appearing in EPA's Integrated Risk
Information System [IRIS]), together with uncertainty factors regarding their applicability to
human populations. Table 3.25 presents a summary of the available RfC and RfD information
obtained from IRIS and EPA's Health Effects Assessment Summary Tables (HEAST). One
proprietary chemical, in the tin-palladium alternative, has an RfD available; this is not reported to
protect the identity of the proprietary chemical.
3-72
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Table 3.25 Summary of RfC and RED Information
Chemical Name "
2-Butoxyethanol
Acetate
2-Ethoxyethanol
Ammonia
Diethylene Glycol
Ethyl Ether and
Acetate
Diethylene Glycol
n-Butyl Ether
Dimethylformamide
Ethylene Glycol
Formaldehyde
Hydrochloric Acid
Isophorone
Methanol
Potassium Cyanide
Silver
Sodium Cyanide
Inhalation
RfC
(mg/m3)
0.02
0.2
0.1
ND
0.02
0.03
ND
ND
0.007
ND
ND
ND
ND
ND
Comments'
(Inhalation)
Rat, 13 weeks,
hematological and liver
effects (EPA, 1995d)c-d
Rabbit, 13 weeks, reduced
spleen, testicular weights,
and white blood cell counts
(EPA, 1996b)
Occupational study, lack of
irritation to workers
exposed to 9.2 ppm
concentration (EPA, 1997)
Inhalation, rat, 7 hours
(EPA, 1995c,d)d
Inhalation, human, 5+
years, 54 workers for
hepatoxicity effects (EPA,
1996b)
Rat, respiratory tract
hyperplasia, lifetime
exposure (EPA, 1995c)
Oral/Dermal
Rfl>
(mg/kg-day)
ND
0.4
ND
2
ND
ND
2
0.2
ND
0.2
0.5
0.05
0.005
0.04
CQmmentsb
(Oral/Derma!)
Gavage, rat and mouse, 103
weeks, reduced body weight,
testicular degeneration, and
enlargement of adrenal gland
(EPA, 1995d)
Oral, rat, 3-generation study
(chronic reproductive),
kidney and bladder damage
(EPA, 1995d)
Oral, rat, 2 years, decreased
growth, renal calculi (EPA,
1995c)
Oral, rat, 2 years, GI tract
and histopathological
changes (EPA, 1995b)
Oral, dog, 90 days, no signs
of cellular changes (EPA,
1995d)
Gavage, rat, 90 days,
decreased brain weights
(EPA, 1995c)
Oral, rat, 2 years, no
treatment effects on weight
gain (EPA, 1995c)
Oral, human, 2 - 9.75 years,
argyria of skin, eyes, mouth,
and throat (EPA, 1996b)
Oral, rat, 2 years
(EPA, 1995c)
3-73
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3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name1
Inhalation
RfC
(Inhalation)
Oral/Dermal
RfD
(mg/kg-day}
Comments5
(Oral/Dermal)
Stannous Chloride
ND
0.62
Rat, 105 weeks (EPA,
| | | ivy^af
* Only those chemicals with available data are listed. Proprietary chemical data are not presented in order to protect
proprietary chemical identities.
b Comments may include exposure route, test animal, duration of test, effects, and source of data.
c Based on data for 2-butoxyethanol.
d Provisional RfC or RfD.
e Based on data for tin.
ND: No data. An RfD or RfC has not been determined for this chemical.
When an RfD or RfC was not available for a chemical, other toxicity values were used,
preferably in the form of a no-observed-adverse-effect level (NOAEL) or lowest-observed-
adverse-effect level (LOAEL). These toxicity values were obtained from the published scientific
literature as well as unpublished data submitted to EPA on chemical toxicity in chronic or
subchronic studies. Typically, the lowest NOAEL or LOAEL value from a well-conducted study
was used. (If study details were not presented or the study did not appear to be valid, the
reported NOAEL/LOAELs were not used.) But unlike the majority of RfD/RfCs,
NOAEL/LOAELs have not received EPA peer-review of the studies on which the values are
based, and uncertainty factors have not been considered.
The LOAEL is the lowest dose level in a toxicity test at which there are statistically or
biologically significant increases hi frequency or severity of adverse effects in the exposed
population over its appropriate control group (in mg/kg-day, or mg/m3 for inhalation). The
NOAEL is the highest dose level in a toxicity test at which there is no statistically or biologically
significant increase in the frequency or severity of adverse effects in the exposed population over
its appropriate control (in mg/kg-day, or mg/m3 for inhalation). LOAEL values are presented
only where NOAELs were not available. Table 3.26 presents a summary of the available
NOAEL and LOAEL values.
Table 3.26 NOAEL/LOAEL Values
Chemical Name"
1,3-Benzenediol
Ammonium Chloride
Benzotriazole
Boric Acid
Inhalation
NOAEL/
L0AELb
(mg/m3)
ND
ND
ND
ND
Comments
(Inhalation)
Oral/Dermal
NOAEL/
LOAEL"
(mg/kg-day)
100(N)C
1,691 (N)
109 (L)
62.5 (L)
Comments
(Oral/Dermal)
Gavage, rat/mouse, 2 years
(NTP, 1992)
Oral, mouse, developmental
study in drinking water
(Shepard, 1986)
Oral, rat, 26 weeks, induced
anemia, endocrine effects
(RTECS, 1995)
Gavage, rabbit,
developmental study showed
cardiovascular defects (U.S.
Borax Co., 1992)
3-74
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name"
r
Carbon Black
Copper (I) Chloride
Diethylene Glycol
Methyl Ether
Diethylene Glycol
n-Butyl Ether
Dimethylformamide
Ethanolamine
Ethylene Glycol
Fluoroboric Acid
Formaldehyde
Formic Acid
Graphite
Inhalation
NOAEL/
LOAEL1*
(mg/m3)
7.2 (L)
0.6 (L)
ND
NA
NA
12.7 (L)
31
ND
0.1ppm(L)
59.2 (N) .
56 (L)
Comments
(Inhalation)
Human, 14 years,
decrease in lung function:
vital capacity (LARC,
1984)
Human, dust caused
leukocytosis/anemia,
respiratory irritant
(U.S. Air Force, 1990)
Rat, dog, guinea pig, 90
days, skin irritation/
weight loss (ACGIH,
1991)
Human, headache,
respiratory tract irritation,
lymphocytosis (ATSDR,
1993)
Human, eye and upper
respiratory tract irritation
(EPA, 1991c)d
Rat/mouse, 2 weeks,
respiratory epithelial
lesions (Katz and Guest,
1994)
Human effect level for
pneumoconiosis, nuisance
from dust (Pendergrass,
1983)
Oral/Dermal
NOAEL/
LOAELb
(mg/kg-day)
ND
0.07 (L)
1,000 (N)
191
125 (L)
320 (N)
NA
0.77
NA
ND
ND
Comments
(Oral/Dermal)
Oral, human, 1.5 years, GI
tract effects (ATSDR, 1990a)
Oral, rat, 13 weeks, kidney
damage, (HSDB, 1995)
Dermal, rat, 90 days,
hemolytic effects (RM1,
1992)
Oral, rat, 100 days, liver
weight increases and body
weight gains (Trochimowicz
etal., 1994)
Oral, rat, 90 days, altered
liver/kidney weights at higher
concentrations (ACGIH,
1991)
Human, 2 years, bone
disease, GI problems &
osteoarticular pain in women
(HSDB, 1995; based on 50-
100 mg/d, for fluorides,
adjusted for 65 kg body
weight)
3-75
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name1*
lydrogen Peroxide
iydroxyacetic Acid
sopropyl Alcohol,
2-Propanol
Magnesium Carbonate
Vlethanol
Palladium, Palladium
Chloride
Potassium Hydroxide
Potassium Sodium
Tartrate
Potassium Sulfate
Sodium Carbonate
Sodium Chlorite
Sodium Hydroxide
Sodium Sulfate
Sulfuric Acid
Inhalation
NOAEt/
LOAEL11
(mg/m5)
79
ND
980 (N)
Comments
(Inhalation)
Mouse, 7/9 died from 79
mg/m3 in 6 weeks (EPA,
1988)
Rat, 13 weeks (SIDS,
1995)
Oral/Dermal
NOAEt/
LOAEL"
(mg/kg»day)
630 (N)
250 (N)
100 (N)
Comments
(Olral/Dermal)
Oral, developmental and
reproductive studies for 5
weeks (rat) and 3 months
(mouse), respectively (IARC,
1985)
Gavage, developmental rat
study showed lung noise,
reduced weight gain
(DuPont, 1995)
Oral, rat, 2-generation study
(CMA, 1995; RM2, 1996)
Generally regarded as safe (U.S. FDA as cited in HSDB, 1995).
1,596 - 10,640
(1,200-8,000
ppm)
ND
7.1
Human, 4 year
occupational study, vapor
caused vision loss
(ACGIH, 1991)
Human, caused
cough/bronchial effects,
severe eye/skin irritant
(Graham et al., 1984)
NA
0.95 (L)
ND
Oral, rat, 180 days, decreased
weight (Schroeder &
Mitchener, 1971)
Generally regarded as safe (U.S. FDA as cited in HSDB, 1996).
15
(TCLO)°
10 (N)
ND
2(L)
ND
0.066 (N)
Rat, 4 hr/d for 17 weeks,
metabolic effects
(RTECS, 1995)
Rat, 4 hr/d, 5 d/w for 3. 5
months, decreased weight
gain, lung effects (Pierce,
1994)
Human, dyspnea, irritant
(ACGIH, 1991)
Human (EPA, 1994a)
ND
ND
10 (N)
ND
420 (N)
ND
Gavage, rat, 13 weeks,
hematological effects
(Harrington et al., 1995)
Oral, rat, 16 weeks (Young,
1992)
3-76
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name*
Tartaric Acid
Triethanolamine; or
2,2',2"-Nitrilotris
Ethanol
Vanillin
Inhalation
NOAEL/
LOAEL&
(mg/m3)
ND
ND
ND
Comments
(Inhalation)
Oral/Dermal
NOAEL/
JjOAEL"
(mg/kg-aay)
8.7
32 (L)
.64 (L)
Comments
(Oral/Dermal)
Oral, dog study, 3/4
developed casts (color or tint)
in urine, weight changes and
advanced renal tubular
degeneration, at 990 g/kg for
90-114 days (Informatics,
Inc., 1974)
Dermal, mouse, 105 weeks,
irritation effects (NTP, 1994)
Oral, rat, 10 weeks, growth
depression and damage to
kidney, myocardium, liver
and spleen (Kirwin and
Galvin, 1993)
Only those chemicals with available data are listed. Proprietary chemical data are not presented in order to protect
proprietary chemical identities.
b When more than one NOAEL and/or LOAEL was available, only the lowest available NOAEL or LOAEL was
used and is listed here. If both NOAEL and LOAEL data are available, the NOAEL is used and is listed here.
0 (N) = NOAEL; (L) = LOAEL. If neither is indicated, the toxicity measure was not identified as a NOAEL or
LOAEL in the available information.
d This value is highly uncertain; precise thresholds for these irritant effects of formaldehyde have not been
established. Estimates based on a large number of clinical and non-clinical observations indicate that most people
have irritant reaction thresholds over the range of 0.1 to 3.0 ppm formaldehyde (EPA, 1991c).
e TCLO = total concentration resulting in a sublethal effect.
ND: No Data. A NOAEL or LOAEL was not available for this chemical.
NA: Not Applicable. A NOAEL or LOAEL is not required because an RfD or RfD was available for this chemical.
Neither RfDs/RfCs nor LOAELs/NOAELs were available for several chemicals in each
MHC process alternative. For these chemicals, no quantitative estimate of risk could be
calculated. EPA's Structure-Activity Team (SAT)10 has reviewed the chemicals without
relevant toxicity data to determine if these chemicals are expected to present a toxicity hazard.
This review was based on available toxicity data on structural analogues of the chemicals, expert
judgement, and known toxicity of certain chemical classes and/or moieties. Chemicals received
a concern level rank of high, medium, or low. Results of the SAT evaluation are presented in
Table 3.27. A summary of the SAT results for proprietary chemicals is presented in Table 3.28.
An overview of chemicals and available toxicity data is presented in Table 3.29.
10
The SAT is a group of expert scientists at EPA who evaluate the potential health and environmental
hazards of new and existing chemicals.
3-77
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Informatio
Table 3.27 Summarv of Health Effects
•c
o
OH
s '1
11
8 g-
.23 -o
*^ S
B "*
This compou
ental toxicity
Absorption is expected to be good via all routes of exposure.
handled in concentrated form. There is concern for developm
effects for the boron.
1
p
r£>
P
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§"*
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1
3
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8
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£
J
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'C rt ^_»
s<;§ i?
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C_) "*"* ^
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111
ell
13 > 0
Expect no absorption by skin, but expect absorption by lungs ;
chelator and is expected to chelate Ca and Mg. Concerns for <
cardiac arrhythmia due to ability to chelate Ca. Arrhythmia e:
doses.
+3
CO
cj
S
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p
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a
0
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"° 8
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||
^ a
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>• _co
rt ^
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'P
CO
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p p
Expect absorption via the skin following irritation. Expect go
tract. This compound is a severe skin irritant and may be con
for developmental toxicity based on information for fluoride.
"S
Q
^*
.0
a
|
8
P
E
a
o
§
•i
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P
e
^
p
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t3 :»1 &
5 1 III
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g g C 04 §
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ill |i
P a £ ^ §
Absorption is expected to be nil through the skin and good thr
nitro group can be reduced to anamine. There is concern for i
aromatic amine compound. As a nitrobenzene derivative, thei
and developmental toxicity. Serious brain damage was noted
study with nitrobenzene. It is expected to be irritating to muc
respiratory tract.
.a
I
3
^ ^
CH ^^
QJ rj
S 3
^ ^O
*o ^
•| 3
a -^
a
OJ
^J
s
(3
"8
0 g
P 0
•5 3
1— 1 "rt
^ 'g
S3 2
CO r/1
60 is
l|
-3 eS
p 60
Absorption is expected to be nil through the skin and good thi
peroxymonosulfate moiety is reactive with moisture (oxidizin
irritant as a concentrated solution.
+2
§ 3
7 CO
'55 P
,2 ^
Q* 5L
2 ^
c o
S pS
g
u
§
!§
2
1
s
o
c>
CO
5
•5
1
HH
0
1
CO
60
Q /-^s
•£ PQ
ll
Absorption is expected to be nil through the skin and good thi
an irritant and is reported to be a dermal sensitizer in humans
d>
12
o
^^H
o
-rt
.3
"3
PM
_ 1
«s ^
ll
0 0
O Qi
1 £
§ g S
T3 2 S
p C co
^ P 23
<5 O -C3
Expect absorption by all routes. Compound is corrosive.
T3
*Q
^(
O
•c
"f
p
s
3-78
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SDMMAKV
a
I-
2 ^
1 **
>
o
I
o
1
2 *£*
*5 3«
«*J &
1
1
a.
1
B
1
o
s
0
T3
O
CO
si
~j t^ ^
r^ O r^
Absorption is expected to be nil through the skin as the neat material and good throuj
lungs and GI tract. Expect absorption via the skin in solution because of damage to t
This compound is expected to be a severe irritant and/or corrosive to the skin, eyes, s
membranes because of its acidity.
1
2
g
•I
J2
0
PH
5
1
i
12
Absorption is expected to be nil through the skin and good through the lungs and GI
irritating to mucous membranes and may cause dermal sensitization (HSDB).
M
Cfl
i
^
K
P
*o
o
W3
S
!
L<
CD
O
T3 _ f~~
u ° 'o
.p _co f-^
g CO C!j CN
§•§ fr . ^
w . M
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Table 3.28 Summary of EPA Structure-Activity Team Results for Proprietary Chemicals
Technology
Electroless Copper
Graphite
Tin-Palladium
Organic-Palladium
No. of
Additional
Trade Secret
Chemicals"
9
5
5
1
No, of Additional Trade
Secret Chemicals With
. No Human Health
ToxiciiyDatab
4
3
4
0
SAT Human Health Concern Rank
(no. of proprietary chemicals)
Low
1
0
2
0
Low-Moderate
2
2
1
0
Moderate
1
1
1
0
* New chemical for this process alternative.
b The toxicity data required to calculate cancer risk, hazard quotient, and MOE were not available.
Table 3.29 Available Toxicity Data for Non-Proprietary Chemicals
Chemical
2-Ethoxyethanol
1,3-Benzenediol
2-Butoxyethanol Acetate;
Butylcellusolve Acetate
Ammonia
Ammonium Chloride
Benzotriazole
Boric Acid
Carbon Black
Copper (I) Chloride; Copper
Copper Sulfate; or Cupric Sulfate"
Diethylene Glycol n-Butyl Ether
Diethylene Glycol Ethyl Ether
Diethylene Glycol Methyl Ether
Dimethylaminoborane
Dimethylformamide
Ethanolamine; Monoethanolamine;
2-Aminoethanol
Ethylene Glycol
Ethylenediaminetetraacetic Acid
(EDTA)
Fluoroboric Acid; Sodium Bifluoride
Formaldehyde
Formic Acid
Graphite
Hydrochloric Acid
Cancer:
Slope Factor {SF)»
Weight-of-Evideiice
(WOE) Classification
WOE
WOE
WOE
WOE
SF, WOE
WOE
Inhalation;
RfC, NOAEL,
or LOAEJL
RfC
RfC
RfC
LOAEL
LOAEL
RfC
RfC
LOAEL
Other"
LOAEL
NOAEL
LOAEL
RfC
Oral/Bermah
RfD,NQAEL*
or LOAEL
RfD
NOAEL
NOAEL
LOAEL
LOAEL
LOAEL
Otherb
RfD
NOAEL
LOAEL
NOAEL
RfD
Otherb
RfD
SAT
•
•
•
•
3-80
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical
Hydrogen Peroxide
Hydroxyacetic Acid
Isophorone
Isopropyl Alcohol; 2-Propanol
Lithium Hydroxide
m-Nitrobenzene Sulfonic Acid;
Sodium m-Nitrobenzenesulfonate
Magnesium Carbonate
Methanol
p-Toluene Sulfonic Acid; Tosic Acid
Palladium
Palladium Chloride
'eroxymonosulfuric Acid;
Potassium Peroxymonosulfate
Phenol-Formaldehyde Copolymer
Phosphoric Acid
Potassium Bisulfate
Potassium Carbonate
Potassium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium Sulfate
Potassium-Sodium Tartrate0
Silver
Sodium Bisulfate
Sodium Carbonate
Sodium Chlorided
Sodium Chlorite
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Persulfate
Sodium Sulfate
Stannous Chloride; Tin (II) Chloride
Sulfuric Acid
Tartaric Acid
Cancer:
Slope Factor (SF),
Weiglii-af-EvKleiice -
(WOE) Classification
WOE
Inhalation:
RfC, NOAEL,
or LOAEL
Otherb
NOAEL
Otherb
Otherb
Otherb
NOAEL
LOAEL
NOAEL
Oral/Dermal?
RfD, NOAEL,
or LOAEL
NOAEL
NOAEL
RfD
NOAEL
RfD
LOAEL
LOAEL
RfD
RfD
NOAEL
RfD
NOAEL
RfD
Other"
SAT
•
•
•
•
•
•
•
•
•
•
•
•
•
•
3-81
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical
Triethanolamine; or 2,2',2"-Nitrilotris
Ethanol
Trisodium Citrate 5.5-Hydrate;
Sodium Citrate
Vanillin
Cancer:
Slope Factor (SF),
Weight-of-Evidence
(WOE) Classification
Inhalation:
RfC,NGAEL,
orLOAETt;
Qral/Bermaij
RfD,KOAEL,
or LOAEL
LOAEL
LOAEL
SAT
•
" The toxicity data for copper (I) chloride was used to evaluate copper sulfate and cupric sulfate.
b Toxicity data other than an RfC, RfD, NOAEL, or LOAEL was used. See Table 3.26 for description of the
toxicity data.
0 Potassium-sodium tartrate added directly to human food is affirmed as generally regarded as safe when
meeting specified food manufacturing requirements (U.S. FDA as cited in HSDB, 1996).
d Sodium chloride (table salt) is a necessary mineral and electrolyte in humans and animals, and under
normal conditions the body efficiently maintains a systemic concentration of 0.9 percent by retaining or
excreting dietary sodium chloride. It is not generally considered poisonous to humans or animals, its main
systemic effect being blood pressure elevation.
Chemicals having potential developmental toxicity were identified based on the data
provided in the toxicity profiles. The data are summarized in Table 3.30. The values listed in
the table included the no-observable-effect level (NOEL) or, in the absence of a NOEL, the
lowest-observable-effect level (LOEL) concentrations. Chemicals which have inconclusive data
concerning the developmental toxicity, as a result of multiple studies having conflicting
conclusions, are identified as possible developmental toxicants. The chemical is listed as a
possible toxicant given the uncertainty in the data.
3-82
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
fc
OS
CO
T3
h
3
«
"3
1
1
ff
u
2
H
+2
1
I
U
-j
3^
|4
»>« <&
•a
A
j
D^^
-S
52; g
l|
^"^ ^w
i
s
«
*§
^
6
^-i
£
TJ"
1
O M
Drinking water, mice, after day 7
gestation. No congenital effects (
1986).
,_,
o\
VO
<— r
-S
3
S
o
a
sj3
O
c
•<
^
fr
3
llg
4) .S
Oral, rabbits, gestation days 6-19.
mortality, interventricular septal c
unspecified malformations (U.S. 1
Co., 1992).
W>
*-o
i — t
T3
"o
.a
g
m
§ +J "72
1 1 1 1| 2 1*-§ 2
^ *^ ^ ^2 c^ *^-J fe J»-j tsO
l|||l||||||
wn3^ £-5^ cn° S "§ °
o £d w3 *^ "o ffl 'ert ^S^ 'rt *O S
&* O ^5 ^ *^ S *^3 ro *~^ f^-.
S S d a ^*s-£r^^ §^S"
-SOT c h o^s
*5 Q^ OH ^ ^ Ar ^3 V"l i d> (D ON
^f, foQ p^ ,J5 fi^ \,^s tf5 i~H J*-* ^ij T3 r— H
S
PH
Dn
O
^_
• "o
m bo
^J O
g|
If
11
"^ *«? "^
!- 4)
O M o
o
o
1 — t
JB
3
"S
a
"o
ca
S a
J>> O
11
PQ ja
c^ .S
^
^
"Sxf
§ s
IB
*= tn
t>o a
Food, mice, 30 days before matin
day 19 of gestation. Malformatio
1984a).
^""7
i—^
in
a
o
O
<(<
^
i S
•tf ""^
Oral, mice, gestation days 6-15.
Malformation of neural tube, heai
and skeletal systems (Price et al.,
3
§
d
o
I^J
^H
T— <
>»
^S
1
"o
o
O
fl5
'S ; s ON
08 S
1 §-€
§ £§:
jj a> •— i
£p<
o d P1-1
S § w
is *
as:§
>? <« S
S «+-! O
_ o -s
S^3 1
>S i u
^ VO CJ
§
§,
ON
CO
w
Q ^
Oral, rats, gestation days 1-21. Ir
major skeletal malformations (EP
1984b).
• ^
m
ON
"o
C3
t>
^~»
1
W
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Comments
d
o ^
If
*§ ^
Comments
o •»
_ =
c^ B
^^
0)
S
M
«MM
.1
n
•_•'
o
0)
"S
§
"o
ra
•s
W
i— *
d oo £7
O ^—'Ov
> and mice, exposure of 6
rs/day, days 6-15 of gestati
il malformations in mice
mcephaly, cleft palate, and
ormal rib and facial bones)
1992b; Union Carbide, 19!
ll ills
o
T— 1
Oral, mice, gestation days 6-15. Lower
body weights and craniofacial and skeletal
malformations (Shell Oil, 1992a).
o
0
tr>
*o
O
0
J
^
rg
W
g
Diet, rats, gestation days 7-14. Maternal-
toxicity and reduced litters, reduced fetal
weight and malformations (EPA, 1987).
^
O
H-}
i
^.
i/~l
0s*
"8
i
S
§
«
c
1 Q
8 o
">•» "O
^ 'o
W <3
g
Subcutaneous, rats, gestation days 11-21.
Injection of 8 mg/kg/day resulted in
reduced ratio of fetal survivors to
unplantation sites, reduced fetal weight,
and 100% mortality of pups within 24 hrs
of birth (Lee and Aleyassine, 1970).
4*
^
Z
a
* e "§ 3 ^
s, exposure of 1 hour/day f(
16 days prior to mating or c
ation day 9. Adults exhibil
tality. Increased fetal morl
reased fetal weight and
eased fetal lung weights (E
5c).
°5 CS S QJ rt ON
K T-I 60 S T3 .9 ^H
^ ^
O
^— '
o
^(
j^<
^<
"2
'o
^^
.0
Q
s
0
o
>>
W
|
fit
JS .2 J2 cr\
'51^1
"S fe S w
•« •§ 2 2
jj
^J
<2n
§
jS
!/3
0}
.s
§
*>•>
2
K*>
ft
3-84
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
|
i
1
^
°x
g J5
•_2 wo
ctt &•
'S vjjt
1
1
o |
l i
^^ P
s^'
tu
si
1
s
a
-S
U
.s
11
« 0
JS^TS "3
C^ QJ TO
O PH ^
||||
§* .2 I' 5
-y "&5 '!S r "i ,
^ a> 8 H
& SO & <,
g
cL^-s
p^ 1
o p3
§§
rn" O
•y
Oral, rabbits, gestation days 6-18.
Reduced fetal body weights noted in oral
exposure of rats, but at concentrations wi
maternal toxicity. No teratogenic effects
noted (Tyl, et al., 1995, as cited in CMA,
1995).
0
oo
"o
§
2
OH
s
H
_g 0 -u ^
Cj -g _60 rj
s? •<§ .sp '| 2
PlN
^H ( IU ^"j £^
>o m "-; a -a
«H -r & fi i
0 « 1 i 1
P M 2 2 >>
s £> i S Q
g-S |.s^
II § |e
111 SI
w bo S T3 a
g
OH
OH
O
^<
^
8
§
c
o
OH
<;
z
s~\ Cft
•>? ea -!-• .tS w
o^ g « "S i_ O
6a>a>5f||-| 1|| a
Tllpli'i^M!
<4H ^H fgT( OT *» *W ,-rl QJ j^j
"0 1 «
111
lit
CO pj K^
^ .2 H
II1I
i7
^
j
^•^
o
"2
VO
Drinking water, folate-deficient rats,
gestation days 6-15. Maternal toxicity
(decreased weight gain) and
developmental toxicity (increased
resorption) observed at drinking water
concentrations of 1% and
2% (Lington and Bevan, 1994).
•^^
j5
"3
^
D
S
3-85
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
13
o
i
o
0
ti
g.^
^* **«!*
p 8
P
g
^c
(5
1 Comments
M jj»
O if
g M
of
1
S5
1
1
O
ll
2-§
p
H
§
in
o
o
G
Dermal, rats, gestation days 8-16 (EPA,
1986). Hydrocephalus, growth retardatio
post-implantation losses, and increase
mortality in offspring (IARC, 1989).
§
cs
o
IS
1
J
%
1
9
• T,
Iz;
^r
z
Oral, rats, gestation days 6-15. Reduced
fetal body weights (EPA, 1996c).
0
"o
g
J3
S
^T
J^
(!)
c/>
Epidemiology study of 226 males
employed at potash mine. After starting
work underground, mean buth weights
increased slightly and there was a decreai
hi male/female ratio (Wiese and Skipper,
1986).
^•"H
GO
^C
^
Oral, rats, day 5 or 7 pre-conception and
one or more days post-conception.
Unspecified toxic effects noted (RTECS,
1996).
*§
P
o
o
so
in
^
g
6
§
•3
o
00
3-86
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
i
9
u
Jlf
I
1
O "^
j£ j§&
C «6
V •&
1
cs
&
1
B
O
Drinking water, rats, 2.5 months prior to
mating through gestational day 20.
Increase in variation of sternum and
increase in crown-rump length. Same
study, oral dose 200 mg/kg/day and 2,800
mg/kg/day via drinking water, gestational
days 8-15, no developmental effects (Perry
etal., 1994).
$i
a
•^t
i— *
OJ
1
3
-g
Oral, mice, gestation days 8-12. No effect
on body weights or litter sizes (Young,
1992). Parentally admulistered dose of 60
mg/kg on day 8 of gestation produced
developmental abnormalities of the
musculosketal system (RTECS, 1995).
o
o
00
O)
1
3
CO
1
o
CO
Oral, mice, 10 consecutive days, no effect
on gestation of fetal survival (Gitilitz and
Moran, 1983). Method of exposure
unknown, rats, gestation days 7-12. 500
mg/kg resulted in teratogenic effects (Wu,
1990, as reported in TOXLINE, 1995).
0
in
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
3.3.3 Ecological Hazard Summary
Table 3.31 presents a summary of the available ecological hazard information. Concern
concentrations (CCs) were determined only for aquatic species (e.g., Daphnia, algae, and/or fish)
using standard EPA methodology. Methods for determining CCs are summarized below.
(Cleaner Technologies Substitutes Assessment: A Methodology and Resources Guide [Kincaid et
al., 1996] presents the methods in more detail.)
Table 3.31 Aquatic Toxicity Information
Chemical Name*
1,3-Benzenediol
2-Butoxyethanol Acetate
2-Ethoxyethanol
Ammonia
Ammonium Chloride
Boric Acid
Carbon Black
Copper
Copper Chloride (Cuprous)
Copper Sulfate
Diethylene Glycol Methyl
Ether
LCjQ
(mg/L)b
>100
0.25
88.6
262
>100
150
960
>500
> 5,000
> 10,000
7,660
0.42-0.84
1.74
1.58
640
139
50
46-75
22-155
79-100
Test
Information
all 96 hr
48hr
17 hr
72 hr
24 hi
96 hr
48hrIC50d
8hr
24 hr
24 hr
24hrTLme
24-96 hr TLm
96 hr TLm
7 day
9 day
28 day
Species
rainbow trout
water flea
minnow
zebra fish
snail
water flea
protozoa
green algae
goldfish
bluegill &
silversides
water flea
rainbow trout
water flea
snail
carp
bluegill
water flea
goldfish
catfish
rainbow trout
CC
(mg/L)'
AsF = 100W
0.0025
AsF = 100W
1.5
AsF = 1,000PJ
5.0
AsF = 100t2)
CC = 0.0042
AsF = 1,000CT
0.05
AsF = l,OOGw
0.022
Source
AQUIRE,
1995
Verschueren,
1996
AQUIRE,
1996;
EPA, 1985a
AQUIRE,
1995
Verscheureri,
1983
AQUIRE,
1995
No information found in literature
0.8-1.9
0.0885-21
0.13-0.5
0.125
10-33
0.40-2.3
0.18-12
0.096-0.12
0.036-1.38
0.002-160
0.10-0.24
0.002-23.6
0.56-40
> 5,000
7,500
96 hr
96 hr
96 hr
96 hr
24 hr
96 hr
96 hr
96 hr
96 hr
96 hr
96 hr
96 hr
96 hr
24 hr
96 hr
carp
minnow
rainbow trout
salmon
shrimp
mummichog
(fish)
bullhead
zebrafish
goldfish
carp
salmon
minnow
oyster
goldfish
minnow
AsF = 100(2)
0.00088
AsF = l,OOOw
0.0004
AsF = 100(2)
0.00002
AsF = l,OOOw
5.0
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
3-88
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name"
Diethylene Glycol
Ethyl Ether
Diethylene Glycol
n-Butyl Ether
Dimethylformamide
Ethanolamine
Ethylene Glycol
Ethylenediaminetetraacetic
Acid (EDTA)
Fluoroboric Acid
Formaldehyde
Formic Acid
Hydrochloric Acid
Hydrogen Peroxide
Isophorone
LCW
(mg/L)b
9,650-26,500
12,900-13,400
15,200
6,010
1,982-4,670
1,300
3,200
1,000
1.2-2.5
1,300
> 1,000
9,860
18,800
170
40&70
140
0.75
41,000
49,000-57,000
41,000-57,600
> 5,000
330
129
625
59.8
41-532
280
125
(as fluoride)
25.2-40
47.2
6.7
25.5-26.3
175
80-90
151
282
100
180
89
12
155
12.9
79
228
Test
Information
96 hr
96 hr
96 hr
96 hr
48 hr
96 hr
EC50f
decreased cell
multiplication
MATC8, chronic
24 hi
48 hr
96 hr
48 hr EC50
96 hr
24hrLC0h&
T P '
J-'Moo
24 hr
8 day, toxicity
threshold
96hr
96hr
48hr
24 hr
48 hr
96 hr
24 hr
96 hr
96 hr, varying pH
24 hi
48 hr
96 hr
96 hr
96 hr
96 hr
24 hr
48 hr
48 hr
24-96 hr
96 hr produced
no stress effects
96 hr
24 hr
228hrLT50j
24 hr
96 hr
NOECk
96 hr
Species
minnow
rainbow trout
mosquito fish
catfish
water flea
bluegill
water flea
blue-green algae
water flea
guppy
medaka
rainbow trout
water flea
goldfish
creek chub
water flea
green algae
rainbow trout
minnow
water flea
goldfish
African frog
catfish
water flea
minnow
bluegill
shrimp
brown trout
bluegill
rainbow trout
striped bass
catfish
bluegill
green crab
water flea
mosquito fish
green crab
goldfish
mackerel
zebra mussel
gobi
mysid shrimp
green algae
minnow
CC
(«tg/Ly
AsF = 100(2)
CC = 20
AsF = 100P)
10
AsF = 10W
CC = 0.12
AsF = 10W
CC = 0.075
AsF = 100(2)
CC = 3.3
AsF = 100(2)
CC = 0.41
AsF = l,OOOPJ
CC = 0.125
AsF = 1,000W
CC = 0.0067
AsF = l,000(3)
CC = 0.08
AsF = 1,000(3)
CC = 0.1
AsF = 10U}
CC=1.2
AsF = 100CT
CC = 0.13
Source
AQUIRE,
1996
AQUIRE,
1995
EPA, 1986
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
Woodiwiss &
Fretwell, 1974
EPA, 1985b
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1996
3-89
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name*
Isopropanol
Lithium Hydroxide
m-Nitrobenzene Sulfonic
Acid
Methanol
Palladium, Palladium
Chloride
Phenol-Formaldehyde
Copolymer
Phosphoric Acid
Potassium Cyanide,
Sodium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium-Sodium Tartrate
Potassium Sulfate
IH-Pyrrole
Silver
Sodium Bisulfate
Sodium Carbonate
LC5tt
(mg/L)b
> 1,400
900-1,100
1,150
1,800
Test
Information
96 hr
24 hr
96 hr
toxicity threshold
Species
mosquito fish
creek chub
shrimp
green algae
CC
(mg/L)'
AsF = 100CT
CC = 9.0
Source
AQUIRE,
1995
No aquatic toxicity information available
8,600
>500
28,200
20,100
1,700
2.6-3.1%
> 10,000
0.237
0.142
24 &48 hr
48 & 96 hr
96 hr
96 hr
48 hr
10-14dayEC50
24hrLC50
24 hr ECSO
48hrEC50
water flea
trout, guppy,
bluegill,
minnow
minnow
rainbow trout
goldfish
algae
brine shrimp
tubificid worm
AsF = 100(2) •
CC = 5
AsF=100(2)
CC = 17
AsF = l,000(3)
CC = 0.00014
AQUIRE,
1995;
Greim et al.,
1994
AQUIRE,
1995
AQUIRE,
1995
No aquatic toxicity information available. Once cured, PF copolymer is highly
insoluble and is not expected to be toxic to aquatic life.
138
0.052
0.057
0.0079
85
80
80
1,360
234
845
92-251
TLm
96 hr
96 hr
chronic value
24 hr
48 hr
96hr
48 hr
48 hr
48 hr
48 hr
mosquito fish
brook trout
rainbow trout
brook trout
mosquito fish
mosquito fish
guppy
carp
rainbow trout
guppy
water flea
AsF = 1,000W
CC = 0.138
AsF = 10U)
CC = 0.79
AsF = 1,000W
CC = 0.08
AsF = 100w
CC = 0.92
No aquatic toxicity information available.
112
1,180
3,550
2,380
210
856
0.0514
0.064
0.036
58
58-80
190
300-320
297
242
524
all 96 hr
96 hr
72 hr EC50
96 hr
96hr
96 hr
98 hr
24 & 48 hr
immobilized after
48hrs
96 hr
50 hr
5 day
96 hr
mussel
adult snail
bluegill
bleak
minnow
protozoan
rainbow trout
bluegill
minnow
minnow
mosquito larvae
water flea
bluegill
guppy
diatom (algae)
water flea
AsF = l,OOOw
CC = 0.11
AsF-l,OOOl3)
CC = 0.21
AsF - I,000t3)
CC = 0.000036
AsF = l,000C3)
CC = 0.058
AsF = 100CT
CC = 2.4
HSDB, 1995
EPA, 1980
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1996
AQUIRE,
1996
AQUIRE,
1995
AQUIRE,
1995
3-90
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name*
Sodium Chloride
Sodium Chlorite
Sodium Citrate
Sodium Hydroxide
Sodium Persulfate
Sodium Sulfate
Stannous Chloride"1
Sulfuric Acid
Tartaric Acid
Tetrasodium EDTA
LC5tt
(mgtt,)b
4,324-13,750
17,550-18,100
23,000-32,000
280-1,940
1,500-5,000
75
0.65
0.161
3,330
125
30
33-100
>25
1,667
64.6
388
631
200-290
81
204
4,380
3,360
0.6
2.1
0.09
0.4
80-90
42
42.5
20
250-320
200
10
360
663
1,033
11
1,030-2,070
Test
Information
24 hr-10 day
25-96 hr
24-96 hr
>24hr
24-96 hr
96 hr
96 hr
48 hr
24 hr
96 hr
24hrLC40'
48 hr
chronic
48 hr
48 hr
48 hr
48 hr
96 hr
96 hr
96 hr
96 hr
32 day
30 day lethal cone
7 day
7 day
28 day
48 hr
96 hr
48 hr
7 day, no
mortality
LD0n
LD0 longtime
hardwater exp.
LD0 longtime
softwater exp.
72 hr
48 hr
EC50
8 day, decreased
cell
multiplication
96 hr
Species
goldfish
mosquito fish
damsel fly
water flea
striped bass
minnow
mysid shrimp
water flea
water flea
mosquito fish
pikeperch
poacher
guppy
carp
water flea
rainbow trout
guppy
amphipoda
bass larvae
water flea
bluegill
Myriophyllum
spicatum
green algae
goldfish eggs
toad eggs
rainbow trout
eggs
poacher
mosquito fish
prawn
water flea
paramecium
goldfish
protozoa
cryptomonad
water flea
green algae
bluegill
cc
(mg/L)c
AsF = 100(2)
CC = 2.8
AsF = 1,000(3)
CC = 0.00016
AsF = 1,000(3)
CC = 3.3
AsF = 10(1)
CC = 2.5
AsF=l,000(3)
CC = 0.065
AsF = 100(2)
CC = 0.81
AsF = 100(2)
CC = 0.0009
AsF = 10(1)
CC = 2.0
AsF = 10(l)
CC=1.0
AsF = 10(1)
CC = 1.1
Source
AQUIRE,
1996
TR-Metro,
1994; Albright
& Wilson,
1992a,b
AQUIRE,
1995
AQUIRE,
1995;
HSDB, 1995
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
AQUIRE,
1995
Verschueren,
1983
AQUIRE,
1995
3-91
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemical Name*
Triethanolamine; or 2,2', (2"-
Nitrilotris Ethanol
Vanillin
LC5&
(mg/L)b
> 5,000
11,800
176-213 mg/kg
1.8
112-121
57-123
Test
Information
24 hr
96 hr
48 hr, LD0
8 day, decreased
cell
multiplication
96 hr
96 hr
Species
goldfish
minnow
carp
green algae
minnow
minnow
CC
(mg/L)c
AsF=10U)
CC = 0.18
AsF = 1,000(3)
CC = 0.057
Source
AQUIRE,
1995
AQUIRE,
1996;
Verschueren,
1996
Only those chemicals with data are listed. Proprietary chemical data are not presented in order to protect
proprietary chemical identities.
b Lethal concentration (LC50) = the concentration of a chemical in water that causes death or complete immobilization
in 50 percent of the test organisms at the end of the specified exposure period. LC50 values typically represent acute
exposure periods, usually 48 or 96 hours but up to 14 days for fish. Units are mg/L unless otherwise noted.
0 Concern concentration (CC) = most sensitive toxicity value (mg/L) •*• AsF. AsF = Assessment (uncertainty) factor.
d Concentration that immobilizes 50 percent of the test population.
e TLm = Median threshold limit value, or tolerance limit median - equivalent to an LC50 value.
f EC50 = Effective concentration to 50 percent of a test population.
8 MATC = Maximum acceptable toxicant concentration. It is generally defined as the geometric mean of the highest
concentration tested at which no significant deleterious effect was observed and the lowest concentration tested at
which some significant deleterious effect was observed.
h LC0 = Estimated maximum concentration that would not result in death of the exposed organisms.
! LC100 = Lethal concentration to 100 percent of a test population.
j LT50 = Time for 50 percent of the test population to die at a preselected concentration.
k NOEC = No-observed effect concentration.
1 LC,,,, = Lethal concentration to 40 percent of a test population.
m Stannous chloride is expected to rapidly dissociate in water under environmental conditions, followed by formation
of tin complexes and precipitation out of the water column. This process would make stannous chloride much less
available for toxic effects to aquatic organisms.
n LD0 = Estimated maximum dose that would not result in death of the exposed organisms.
(l> Chronic data available and was most sensitive endpoint, AsF =10.
<2) Acute data available for multiple species and trophic levels, AsF = 100.
P) Limited acute data available, AsF = 1,000.
w AsF of 10 used for MATC data.
The CC for each chemical in water was calculated using the general equation:
CC = acute or chronic toxicity value -*- AsF
where:
CC = aquatic toxicity concern concentration, the concentration of a chemical in the
aquatic environment below which no significant risk to aquatic organisms is expected.
AsF = assessment factor (an uncertainty factor), the adjustment value used in the
calculation of a CC that incorporates the uncertainties associated with: 1) toxicity data
(e.g., laboratory test versus field test, measured versus estimated data); 2) acute exposures
versus chronic exposures; and 3) species sensitivity. This factor is expressed as an order
of magnitude or as a power often (EPA, 1984c).
3-92
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
If several acute or chronic toxicity values are available, the lowest one is used (most sensitive
tested species), unless poor or uncertain data quality disqualifies one or more of the values. The
AQUIRE database, an extensive source of aquatic toxicity data, includes a numerical rating of
study quality.
AsFs are dependent on the amount and type of toxicity data contained in a toxicity profile
and reflect the amount of uncertainty about the potential effects associated with a toxicity value.
In general, the more complete the toxicity profile and the greater the quality of the toxicity data,
the smaller the AsF used.
The following approach was used, depending on availability and type of data:
• If the toxicity profile only contained one or two acute toxicity values (no chronic values),
AsF = 1,000 and the CC was calculated by using the lower acute value.
• If the toxicity profile contained three or more acute values (no chronic values), AsF = 100
and the CC was calculated by using the lowest acute value.
• If the toxicity profile contained at least one chronic value, and the value was for the most
sensitive species, AsF = 10 and the CC was calculated by using the lowest chronic value.
Otherwise, AsF =100 and the CC was calculated with the acute value for the most
sensitive species.
• If the toxicity profile contained field toxicity data, AsF = 1 and CC was calculated by
using the lowest value.
Aquatic toxicity values were estimated using the ECOSAR program (EPA, 1994b) for
chemicals without available measured acute or chronic aquatic toxicity data. These values are
presented in Table 3.32. An AsF of 1,000 was used to calculate all CCs based on such estimates.
Table 3.33 presents chemicals with aquatic toxicity CCs. The chemicals are listed in
ascending order (i.e., the chemical with the lowest CC to the chemical with the highest CC for
each of the alternatives). The lowest CC is for copper sulfate, based on fish toxicity data. The
table also presents aquatic hazard concern levels; chemicals were assigned to aquatic toxicity
concern levels according to the following EPA criteria:
For chronic values:
< 0.1 mg/L High concern
> 0.1 to ^ 10 mg/L Moderate concern
> 10 mg/L Low concern
For acute values:
< 1 mg/L High concern
> 1 to ^ 100 mg/L Moderate concern
> 100 mg/L Low concern
Chronic toxicity ranking takes precedence over the acute ranking.
3-93
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
It should be noted that aquatic hazard concern levels are derived from the lowest toxicity
value available. Therefore, these rankings are derived separately from the CCs which are derived
based on the amount of toxicity data available for a given chemical. A summary of the aquatic
toxicity results for the known proprietary chemicals is presented in Table 3.34.
These rankings are based only on chemical toxicity to aquatic organisms, and are not an
expression of risk. The number of chemicals with a high aquatic hazard concern level include
two in carbon, two in conductive ink, none in the conductive polymer process, nine in the
electroless copper process, three in graphite, three in non-formaldehyde electroless copper, two in
organic-palladium, and nine in tin-palladium.
Table 3.32 Estimated Ecological (Aquatic)Toxicity Information for
Non-Proprietary Chemicals
Chemical
Benzotriazole(I)
Dimethylaminoborane(2)
Graphite(2)
Hydroxyacetic Acid(1)
Magnesium Carbonate(2)
Peroxymonosulfuric
Acid(2)
Potassium Bisulfate(2)
Potassium Carbonate(2)
p-Toluene Sulfonic
Acid«
Sodium Hypophosphite(2)
Acute Toxiciiy
(ttlg/L)
Fish (FW)
96 hr
LCSO
45.3
10
*
> 1,000 *
>100
<3.0
> 1,000
1,300
Daphnid
48 hr
LC5a
378.1
0.7
*
> 1,000 *
140
<3.0
>100
330
Green Algae
96 hr
EC5(X
23.4
3.0
*
> 1,000 *
>100
<3.0
>100
100
Chronic Toxicity
(mg/L)
Ffeh
14 day
LCSO
ND
1.0
*
ND
>10
<0.30
>100
100
DaphnM
16 day
ECSO
ND
0.070
*
ND
82
<0.30
>10
190
Green Algae
>96hr
ChV
ND
0.3
*
ND
>10
<1.0
>10
>30
Predicted toxicity values of environmental base set all > 100 mg/L,
chronic values all > 10.0 mg/L based on SARs for anionic LAS
surfactants.
>100
>100
0.030
>10
>10
0.060
AsF,
CC
(mg/L)
1,000
0.023
10
0.007
1,000
1
10
>1.0
10
0.030
10
>1.0
10
>3.0
10
1.0
10
0.006
(1> ECOSAR Program.
p) SAT Report.
* No adverse effects expected in a saturated solution.
ND: No Data. ECOSAR (EPA, 1994b) did not include an estimating component for this endpoint for the chemical
class.
3-94
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Table 3.33 Aquatic Hazard Concern Concentrations (CCs) and Hazard Concern Levels
by MHC Technology for Non-Proprietary Chemicals
Chemicals in MHC Processes"
CCs
(ittg/k)
Aquatic Hazard Concern
LfeV6lfr
Electroless Copper
Copper Sulfate
Palladium; Palladium Chloride
Sodium Chlorite
Copper Chloride
Stannous Chloride0
Sodium Hypophosphite
Formaldehyde
Dimethylaminoborane
Boric Acid
Benzotriazole
Peroxymonosulfuric Acid
Ammonium Chloride
Sodium Bisulfate
Ethanolamine
Potassium Hydroxide
Formic Acid
Potassium Hydroxide
Hydrochloric Acid
Potassium Sulfate
Dimethylformamide
Fluoroboric Acid
Triethanolamine; or 2,2',2"-Nitrilotris
Ethanol
Ethylenediaminetetraacetic Acid (EDTA)
Sodium Cyanide
Potassium Cyanide
Sodium Sulfate
Potassium Persulfate
Hydroxyacetic Acid
Magnesium Carbonate
p-Toluene Sulfonic Acid
Tartaric Acid
Potassium Bisulfate
Hydrogen Peroxide
Sulfuric Acid
0.00002(2)
0.000 14(3)
0.00016(3)
0.0004(3)
0.0009(2)
0.006(5)
0.0067(3)
0.007(5)
0.022(3)
0.023(5)
0.030(5)
0.05<3>
0.058(3)
0.075(I)
0.08(3)
0.08(3)
0.08(3)
0.1(3)
0.11®
0.12(4)
0.125(3)
0.1 8^
0.41®
0.79«
0.79(1)
0.81(2)
0.92(2)
!(5)
1.0(5)
l.O®
1.0(1)
>1.0(5)
1.2<»
2.0(1)
High(A)
High(A)
High(A)
High(A)
High(A)
Low(A)
Moderate(A)
High(c)
Moderate(A)
Moderate0"0
Moderate(c)
Moderate(A)
Moderate(A)
High(A)
Moderate(A)
Moderate(A)
Moderate(A)
Moderate(A)
Low(A)
Moderate(C)
Low(A)
Moderate(C)
Moderate(A)
High
High(C)
Moderate(A)
Moderate(A)
Low(A)
Low(C>
Low(C)
Moderate(C)
Low
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemicals in MHC Processes*
Sodium Carbonate
Sodium Hydroxide
ithylene Glycol
m-Nitrobenzene Sulfonic Acid
2-Ethoxyethanol
sopropanol
Vlethanol
Potassium-Sodium Tartrate
CC$
(mg/L)
2.4<2>
2.5«
3.3(2)
5(2)
5.0(3)
9.0(2)
17®
Aquatic Hazard Concern
Level6
Low(A)
Low(C)
Low(A)
Low(A)
Low(A)
Low(A)
Low(A)
no data available
Carbon
Copper Sulfate
Sodium Persulfate
Ethanolamine
Potassium Hydroxide
Sulfuric Acid
Potassium Carbonate
Ethylene Glycol
Carbon Black
0.00002(2)
0.065(3)
0.075(1)
0.08(3)
2.0'1'
>3.0(5)
3.3(2)
High(A)
Moderate(A)
High(A)
Moderate(A)
Low(c)
Low(C)
Low(A)
no data available
Conductive Ink
Silver
Copper
Isophorone
2-Butoxyethanol Acetate
Diethylene Glycol Methyl Ether
Diethylene Glycol n-Butyl Ether
Methanol
Diethylene Glycol Ethyl Ether
Graphite
Phenol-Formaldehyde Copolymer
Carbon Black
0.00003 6(3)
0.00088(2)
0.13<2>
1.5®
5.0(3)
10(2)
1?(2)
20(2)
not expected to be toxic(5)
not expected to be toxic(5)
High(A)
High(A)
Moderate(A)
Low(A)
Low(A)
Low(A)
Low(A)
Low(A)
Low
Low
no data available
Conductive Polymer
Peroxymonosulfuric Acid
Phosphoric Acid
IH-Pyrrole
Sulfuric Acid
Sodium Carbonate
Sodium Hydroxide
0.03 0(5)
0.138(3)
0.21<3>
2.0(1)
2.4(2)
2.5(1)
Moderate(C)
Low(A)
Low(A)
Low(C)
Low(A)
Low
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemicals in MHC Processes8
CCs
(mg/Ii)
Aquatic Hazard Concern
Levelb
Graphite
Copper Sulfate
Ammonia
'eroxymonosulfuric Acid
Sodium Persulfate
ithanolamine
Sulfuric Acid
Potassium Carbonate
Graphite
0.00002(2)
0.0042(2)
0.030(5)
0.065(3)
0.075(1)
2.0(1)
>3.0(5)
not expected to be toxic(5)
High(A)
High(A)
Moderate(C)
Moderate(A)
High(A)'
Low
Low(C)
Low
Von-Formaldehyde Electroless Copper
Copper Sulfate
Sodium Chlorite
Stannous Chloride0
Potassium Hydroxide
Hydrochloric Acid
Potassium Persulfate
Hydrogen Peroxide
Sulfuric Acid
Sodium Hydroxide
[sopropanol
0.00002(2)
0.00016(3)
0.0009(2)
0.08(3)
0.1®
0.92(2)
1.2<»
2.0«
2.5«
9.0®
High(A)
High(A)
High(A)
Moderate(A)
Moderate(A)
Moderate(A)
Low(C)
Low(C)
Low(C)
Low(A)
Organic-Palladium
Sodium Hypophosphite
Sodium Bisulfate
Sodium Persulfate
Hydrochloric Acid
Sodium Carbonate, Sodium Bicarbonate
Sodium Citrate
0.006(5)
0.058(3)
0.065(3)
0.1<3)
2.4<2>
3.3(3)
High(C)
Moderate(A)
Moderate(A)
Moderate(A)
Low(A)
Low
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
Chemicals in MHC Processes"
Ethanolamine
Hydrochloric Acid
Fluoroboric Acid
Phosphoric Acid
Triethanolamine; or 2,2',2"-NitriIotris
Ethanol
Hydrogen Peroxide
Sulfuric Acid
Sodium Hydroxide
Sodium Chloride
Potassium Carbonate
Isopropanol
Lithium Hydroxide
CCs
(mgyt)
0.075(1)
0.1®
0.125(3)
0.14®
0.1 8«
1.2®
2.0W
2.5<'>
2.8<2>
>3.0(5)
9.0(2)
Aquatic Hazard Concern
Level6
High(A)
Moderate(A)
Low(A)
Low(A)
Moderate(C)
Low
Low(A)
Low(c)
Low(A)
no data available
' Different supplier's product lines do not necessarily include all of the chemicals listed for a process alternative.
b Based on lowest available toxicity data:
(A) indicates the lowest acute value was used for hazard ranking.
(C) indicates the hazard ranking is based on a chronic value, if available and lower than any acute value.
c Stannous chloride is expected to rapidly dissociate in water under environmental conditions, followed by tin
forming complexes and precipitating out of the water column. This process would make stannous chloride much less
available for toxic effects to aquatic organisms.
Basis of Concern Concentrations:
(1) Chronic data.
(2) Acute data for multiple species and taxonomic groups.
w Limited acute data.
(4) Chronic MATC.
(5) Structure-activity relationship estimate using the ECOSAR program or SAT report.
Table 3.34 Summary of Aquatic Toxicitv for Proprietary Chemicals
Technology
Electroless Copper
Graphite
Tin-Palladium
Organic-Palladium
No. of Additional
Trade Secret
Chemicals*
9
5
5
1
Aquatic Toxicity
Concern Rank
Low
6
4
2
0
Moderate
3
1
1
0
High
0
0
2
1
cc
(rog/l)
<10
1
1
1
0
1 Includes chemicals not previously identified in the publicly-available bath chemistry data for a technology.
3.3.4 Summary
For human health hazards, toxicity data in the form of RfDs, RfCs, NOAELs, LOAELs,
and cancer slope (cancer potency) factors were compiled for inhalation and dermal pathways.
Formaldehyde was the only non-proprietary chemical with an established cancer slope (cancer
potency) factor. Other non-proprietary chemicals in the MHC processes are suspected
carcinogens, but do not have established slope factors. Dimethylformamide and carbon black
3-98
-------
3.3 HUMAN HEALTH AND ECOLOGICAL HAZARDS SUMMARY
have been determined by IARC to possibly be carcinogenic to humans (IARC Group 2B).
Dimethylformamide is used by at least one supplier in the electroless copper process. Carbon
black is used in the carbon and conductive ink processes. -Two proprietary chemicals used in the
graphite and electroless copper processes, cyclic ether and alkyl oxide, have cancer slope factors.
Another.proprietary chemical used in the electroless copper process, trisodium acetate amine B, is
possibly carcinogenic to humans but does not have an established slope factor.
An ecological hazards assessment was performed based on chemical toxicity to aquatic
organisms. Concern concentrations (CCs) were estimated for MHC chemicals using an
established EPA method. A CC is an acute or chronic toxicity value divided by an assessment
factor (AsF). AsFs are dependent on the amount and type of toxicity data contained in a toxicity
profile and reflect the amount of uncertainty about the potential effects associated with a toxicity
value. Concern concentrations were determined for aquatic species (e.g., Daphnia, algae, and/or
fish). The lowest CC is for copper sulfate, based on fish toxicity data.
Chemicals were also ranked for aquatic toxicity concern levels using established EPA
criteria (high, moderate, and low concern) based on the available toxicity data. The number of
chemicals with a high aquatic hazard concern level include nine in the electroless copper process,
two in carbon, two in conductive ink, none in conductive polymer, three in graphite, three in non-
formaldehyde eleetroless copper, and nine in the tin-palladium process, and two in the organic
palladium process.
3-99
-------
3.4 RISK CHARACTERIZATION
3.4 RISK CHARACTERIZATION
Risk characterization is the summarizing step of a risk assessment, which integrates the
hazard and exposure assessment components and presents overall conclusions. Risk
characterization typically includes a description of the assumptions, scientific judgments, and
uncertainties that are part of this process. There are several types of risk assessment ranging
from screening level to comprehensive, and differing according to framework: site-specific,
single chemical, or multiple chemical. This risk assessment is best described as a screening level
assessment of multiple chemicals identified as belonging to a particular use cluster (MHC) in the
PWB industry. This is a screening level, rather than a comprehensive risk characterization, both
because of the predefined scope of the assessment and because of exposure and hazard data
limitations. The intended audience of this risk characterization is the PWB industry and others
with a stake in the practices of this industry.
The focus of this risk characterization is on chronic (long-term) exposure to chemicals
that may cause cancer or other toxic effects rather than on acute toxicity from brief exposures to
chemicals. The focus is also on those health effects from chronic exposures that could be used to
measure risk. In addition, this risk characterization does not consider chemical persistence. The
Process Safety Assessment (Section 3.5) includes further information on chemical safety
concerns.
The goals of the PWB project risk characterization are:
• To present conclusions and uncertainties associated with a screening level health risk
assessment of chemicals used in the MHC process of PWB manufacture.
• To integrate chemical hazard and exposure information to assess risks from ambient
environment and occupational exposures from the MHC process.
• To use reasonable and consistent assumptions across alternatives, so health risks
associated with one alternative can be compared to the health risks associated with other
alternatives.
• To identify the areas of concern that differ among the substitutes in a manner that
facilitates decision-making.
This section contains a summary of the exposure assessment (Section 3.4.1), the human
health hazards assessment (Section 3.4.2), a description of methods used to calculate risk
indicators (Section 3.4.3), results (Section 3.4.4), discussion of uncertainties (Section 3.4.5), and
conclusions (Section 3.4.6). Detailed exposure data are presented separately in the Exposure
Assessment (Section 3.2) and in Appendix E.
3.4.1 Summary of Exposure Assessment
The exposure assessment uses a "model facility" approach, where as much as possible,
reasonable and consistent assumptions are used across alternatives. Data to characterize the
model facility and exposure patterns for each process alternative were aggregated from a number
of sources, including PWB shops in the U.S. and abroad, supplier data, and input from PWB
manufacturers at project meetings. Thus, the model facility is not entirely representative of any
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3.4 MSK CHARACTERIZATION
one facility, and actual exposure (and risk) could vary substantially, depending on site-specific
operating conditions and other factors.
Chemical exposures to PWB workers and the general population were estimated by
combining information gathered from industry (EPC Workplace Practices Questionnaire and
Performance Demonstration data, MSDSs, and other available information) with standard EPA
exposure assumptions (e.g., for inhalation rate, surface area of dermal contact, and other
parameters). The pathways identified for potential exposure from MHC process baths were
inhalation and dermal contact for workers, and inhalation contact only for the general populace
living near a PWB facility.
The possible impacts from chemical spills are not addressed due to the pre-defined scope
of this assessment. In addition, environmental releases to surface water were not quantified
because chemical constituents and concentrations in wastewater could not be adequately
characterized for the MHC line alone. This is because PWB manufacturers typically combine
wastewater effluent from the MHC process line with effluent from other PWB manufacturing
processes prior to on-site wastewater pretreatment. The pretreated wastewater is then discharged
to a POTW. Many PWB manufacturers measure copper concentrations in effluent from on-site
pretreatment facilities in accordance with POTW discharge permits, but they do not measure
copper concentrations in MHC line effluent prior to pretreatment. Because there are many
sources of copper-contaminated wastewater in PWB manufacturing, the contribution of the MHC
line to overall copper discharges could not be estimated. Furthermore, most of the MHC
alternatives contain copper, but because these technologies are only now being implemented in
the U.S., their influence on total copper discharges from a PWB facility cannot be determined.
Finally, while data are available on copper discharges from PWB facilities, data are not available
for some of the other metals found in alternatives to electroless copper. Although ecological
hazards are assessed in Section 3.3, without exposure or release data a comparative evaluation of
ecological (aquatic) risk could not be performed.
Inhalation exposure could occur by breathing air containing vapor or aerosol-phase
chemicals from the MHC process line. Inhalation exposures to workers from non-conveyorized
lines are estimated in the exposure assessment. Inhalation exposure to workers from
conveyorized MHC lines is assumed to be negligible because the lines are typically enclosed and
vented to the outside. The model used to estimate daily inhalation exposure is from the EPA
Chemical Engineering Branch Manual for the Preparation of Engineering Assessments (EPA,
1991a):
= (Cm)(b)(h)
where:
I = daily inhalation potential dose rate (mg/day)
Cm = airborne concentration of substance (mg/m3)
b = inhalation rate (nrYhr)
h = duration (hr/day)
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3.4 RISK CHARACTERIZATION
Daily exposures are then averaged over a lifetime (70 years) for carcinogens, and over the
exposure duration (e.g., 25 years working in a facility) for non-carcinogens/1 using the following
equations:
For carcinogens:
LADD = (I)(EF)(ED)/[(BW)(ATCAR)]
For non-carcinogens:
ADD = (I)(EF)(ED)/[(BW)(ATNC)]
where:
LADD
ADD
EF
ED
BW
AT
NC
= lifetime average daily dose (mg/kg-day)
= average daily dose (mg/kg-day)
= exposure frequency (days/year)
= exposure duration (years)
= body weight (kg)
= averaging time for carcinogenic effects (days)
= averaging time for non-carcinogenic chronic effects (days)
The daily intake for inhalation exposure to workers was calculated by first modeling
chemical emissions from MHC baths with three air-transport mechanisms: liquid surface
diffusion (desorption), bubble desorption, and aerosol generation and ejection. This chemical
emission rate was combined with data from the EPC Workplace Practices Questionnaire and
Performance Demonstration regarding process room size and air turnover rate to estimate an
average indoor air concentration for the process area. An uncertainty and sensitivity analysis of
the air transport models suggests that the air turnover (ventilation) rate assumption greatly
influences the estimated air concentration in the process area because of its large variability (see
the Exposure Assessment, Section 3.2.3).
Inhalation exposure to a hypothetical population located near a model PWB facility was
estimated using the Industrial Source Complex - Long Term (ISCLT) air dispersion model. The
modeled air concentrations of each contaminant were determined at 100 meters radially from a
PWB facility, and the highest estimated air concentration was used. This model estimates air
concentrations from the process bath emission rates for all processes. These emissions were
assumed to be vented to the ambient environment at the rate emitted from the baths. Inhalation
exposures estimated for the public living 100 meters away from a PWB facility were very low
(approximately 10,000 times lower than occupational exposures).
11 Different averaging times are used for characterizing risk for carcinogenic and non-carcinogenic effects.
For carcinogenic agents, because even a single incidence of exposure is assumed to have the potential to cause
cancer throughout an individual's lifetime, the length of exposure to that agent is averaged over a lifetime. An
additional factor is that the cancer latency period may extend beyond the period of working years before it is
discernible. For chemicals exhibiting non-cancer health effects from chronic (longer-term) exposure, where there is
an exposure threshold (a level below which effects are not expected to occur), only the time period when exposure is
occurring is assumed to be relevant and is used as the averaging time.
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3.4 RISK CHARACTERIZATION
Dermal exposure could occur when skin comes in contact with the bath solution while
dipping boards, adding bath replacement chemicals, etc. Although the data suggest that most
MHC line operators do wear gloves, it was assumed in this evaluation that workers do not wear
gloves to account for the fraction that do not. Otherwise, dermal exposure is expected to be
negligible. For dermal exposures, the flux of a material through the skin was estimated based on
EPA, 1992a:
D
where:
D
S
c
f
h
= (S)(C)(f)(h)(0.001)
dermal potential dose rate (mg/day)
surface area of contact (cm2)
concentration of chemical in the bath (mg/L)
flux through skin (cm/hour)
duration (hours/day)
with a conversion factor of 0.001 (L/cm3)
It should be noted that the above equation was developed for exposures with an infinite
volume of liquid or boundary layer contacting the skin, such as swimming or bathing.
Occupational conditions of dermal contact are likely to be more finite in comparison, resulting in
possible overestimates of flux through the skin.
As for inhalation, daily dermal exposures were then averaged over a lifetime for
carcinogens, and over the exposure duration for non-carcinogens, using the following equations:
For carcinogens:
LADD = (D)(EF)(ED)/[(BW)(ATCAR)]
For non-carcinogens:
ADD = (D)(EF)(ED)/[(BW)(ATNC)]
For dermal exposure, the concentration of chemical in the bath and duration of contact for
workers was obtained from publicly-available bath chemistry data, disclosed proprietary
chemical information, and IPC Workplace Practices Questionnaire information, respectively. A
permeability coefficient (rate of penetration through skin) was estimated for organics and a
default rate assumption was used for inorganics. Reliance on such estimates in the absence of
data is a source of uncertainty in the exposure assessment.
Key assumptions in the exposure assessment include the following:
• For dermal exposure, it was assumed that line operators do not wear gloves. Although
the data suggests that most MHC line operators do wear gloves, it was assumed for this
evaluation that workers do not wear gloves to account for the subset of workers who do
not wear proper personal protective equipment.
• For dermal exposure, it was assumed that all non-conveyorized lines are manual hoist.
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3.4 RISK CHARACTERIZATION
• The worker is assumed to have potential dermal contact for the entire time spent in the
MHC area, divided equally among the baths. This does not mean that a worker has both
hands immersed in a bath for that entire time; but that the skin is in contact with bath
solution (i.e., the hands may remain wet from contact). This assumption may result in an.
overestimate of dermal exposure.
• For estimating ambient (outdoor) air concentrations, it was assumed that no air pollution
control technologies are used to remove airborne chemicals from facility air prior to
venting it to the outside.
• For inhalation exposure to workers, it was assumed that chemical emissions to air in the
process room from conveyorized lines are negligible, and that no vapor control devices
(e.g., bath covers) are used on baths in non-conveyorized lines.
• For air concentrations, the model assumes complete mixing in the process room and that
concentrations do not change with time (steady state).
• For all exposures, it was assumed that there is one MHC process line and one line
operator per shift in a process area.
• For characterizing the chemical constituents in the MHC process baths, it was assumed
that the form (speciation) and concentration of all chemicals in the baths are constant over
time, and that MSDSs accurately reflect the concentrations in product lines. If reported
constituent weight percents on an MSDS total less than 100 percent, the remainder is
assumed to be water. These assumptions are discussed further below.
The exposure assessment does not account for any side reactions occurring in the baths
(e.g., the Cannizarro side reaction, which involves the reaction of formaldehyde in electroless
copper baths). A study performed by Merix Corporation found that for every one mole of
formaldehyde reacting in the intended copper deposition process, approximately one mole was
reacting with hydroxide in a Cannizarro side reaction to produce formate ion and methanol
(Williamson, 1996). Other studies have found that the Cannizarro reaction tendency increases
with the alkalinity of the bath. The exposure assessment assumed that the formaldehyde in the
bath is not reacted, and is available to be emitted as formaldehyde. This assumption could tend
to overestimate formaldehyde exposures, and thus risk. However, if side reactions are occurring
with other chemicals that result in the formation of other toxic chemicals (such as methanol), risk
from these chemicals could be underestimated. A search for literature references to studies of
side reactions occurring in PWB baths did not produce sufficient information to quantify the risk
of reaction products in this risk characterization.
Chemical concentrations in baths are based on publicly-available chemistry data,
including MSDSs, partial proprietary chemical information, and supplier Product Data Sheets
that describe how to mix and maintain chemical baths. Many MSDSs provided concentration
ranges for chemical constituents instead of absolute concentrations, in which case it was assumed
that a chemical is present at the mid-point of the reported concentration range. This assumption
may either overestimate or underestimate risk for chemicals, depending on their actual
concentrations.
Using MSDS data for an exposure assessment can also lead to an underestimate of overall
risk from using a process because the identities of many proprietary ingredients are not included
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3.4 RISK CHARACTERIZATION
in the MSDSs. Efforts were made to obtain this information from suppliers of MHC bath
formulations and proprietary information has been received from three of the seven suppliers.12
Assumptions and parameter values used in these equations and results of the exposure
calculations are presented in the Exposure Assessment (Section 3.2). In order to provide
information about the position an exposure estimate has in the distribution of possible outcomes,
exposure (or risk) descriptors are used following EPA's (EPA, 1992b) Guidelines for Exposure
Assessment. For this risk characterization, the exposure assessment uses whenever possible a
combination of central tendency (either an average or median estimate) and high-end (90th
percentile)13 assumptions, as would be used for an overall high-end exposure estimate. The 90th
percentile is used for:
• Hours per day of workplace exposure.
• Exposure frequency (days per year).
• Exposure duration in years (90th percentile for occupational and 95th percentile for
residential exposures).
• The time and frequency of chemical bath and filter replacements, conveyor equipment
cleaning and chemical bath sampling (minutes per occurrence and number of occurrences
per year).
• Estimated workplace air concentrations.
Average values are used for:
• Body weight.
• Concentration of chemical in bath.
• The number of baths in a given process.
Some values used in the exposure calculations, however, are better characterized as "what-if,"
especially pertaining to bath concentrations, use of gloves, and process area ventilation rates for
the model facility. ("What-if represents an exposure estimate based on postulated questions,
making assumptions based on limited data where the distribution is unknown.) Because some
part of the exposure assessment for both inhalation and dermal exposures qualifies as a "what-if
descriptor, the entire assessment should be considered "what-if."
12 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project. Atotech provided information on one proprietary ingredient. W.R. Grace was
preparing to transfer information on proprietary chemical ingredients in the conductive ink technology when it was
determined that this information was no longer necessary because risk from the conductive ink technology could not
be characterized. The other suppliers participating in the project (Enthone-OMI, MacDermid, and Shipley) declined
to provide proprietary information on their MHC technologies. The absence of information on proprietary chemical
ingredients is a significant source of uncertainly in the risk characterization. Risk information for proprietary
ingredients, as available, is presented in this CTSA, but chemical identities, concentrations., and chemical properties
are not listed.
13 For exposure data from the IPC Workplace Practices Questionnaire, this means that 90 percent of the
facilities reported a lower value, and ten percent reported a higher value.
__
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3.4 RISK CHARACTERIZATION
3.4.2 Summary of Human Health Hazards Assessment
Toxicity data in the form of RfDs, RfCs, NOAELs, LOAELs, and cancer slope (cancer
potency) factors were compiled for inhalation and dermal pathways. CCs and aquatic toxicity
hazard ranks for aquatic species were calculated from aquatic toxicity data on PWB chemicals,
but ecological risk characterization was not carried out because the aquatic exposure could not be
estimated.
Formaldehyde was the only non-proprietary chemical with an established cancer slope
(cancer potency) factor. Other non-proprietary chemicals in the MHC processes are suspected
carcinogens, but do not have established slope factors. Dimethylformamide and carbon black
have been determined by IARC to possibly be carcinogenic to humans (IARC Group 2B).
Dimethylformamide is used by at least one supplier in the electroless copper process. Carbon
black is used in the carbon and conductive ink processes. Because slope factors (cancer potency
values) are needed for quantitative estimates of cancer risk, cancer risk results are only presented
for formaldehyde. Two proprietary chemicals used in the graphite and electroless copper
processes, cyclic ether and alkyl oxide, have cancer slope factors. One proprietary chemical used
in the electroless copper process, trisodium acetate amine B, was determined to possibly be
carcinogenic to humans but does not have an established slope factor.
3.4.3 Methods Used to Calculate Human Health Risks
Estimates of human health risk from chemical exposure are characterized here in terms of
excess lifetime cancer risk, hazard quotient (HQ), and margin of exposure (MOE). This section
defines these risk indicators and discusses the methods for calculating each of them.
Cancer Risk
Cancer risks are expressed as the excess probability of an individual developing cancer
over a lifetime from chemical exposure. For chemicals classified as carcinogens, an upper bound
excess lifetime cancer risk, expressed as a unitless probability, was estimated by the following
equation:
cancer risk = LADD x slope factor
where:
Cancer Risk = the excess probability of developing cancer over a lifetime as a result ot
exposure to a potential carcinogen. The estimated risks are the upper bound excess
lifetime cancer risks for an individual. (Upper bound refers to the method of determining
a slope factor, where the upper bound value for the slope of the dose-response curve is
used. Excess means the estimated cancer risk is in addition to the already-existing
background risk of an individual contracting cancer from all other causes.)
LADD = the lifetime average daily dose, the estimated potential daily dose rate received
during the exposure duration, averaged over a 70-year lifetime (in mg/kg-day). LADDs
were calculated in the Exposure Assessment (Section 3.2).
Slope factor (q! *) is defined in Section 3.3.1.
^_^___^^^^^___^^^—^^——•^^^^^^^^^^^^••••^^•••••^^^••••^•••'^^•'
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3.4 MSK CHARACTERIZATION
Non-Cancer Risk Indicators
Non-cancer risk estimates are expressed either as a HQ or as a MOE, depending on
whether or not RfDs and RfCs are available. There is generally a higher level of confidence in
the HQ than the MOE, especially if the HQ is based on an RfD or RfC that has been peer-
reviewed by EPA. If an RfD or RfC is available, the HQ is calculated to estimate risk from
chemicals that exhibit chronic, non-cancer toxicity. (RfDs and RfCs are defined in Section
3.3.2.) The HQ is the unitless ratio of the RfD (or RfC) to the potential dose rate. For MHC
chemicals that exhibit non-cancer toxicity, the HQ was calculated by:
HQ = ADD/RfD
where:
ADD = average daily dose rate, the amount of a chemical ingested, inhaled, or applied to
the skin per unit time, averaged over the exposure duration (in mg/kg-day). ADDs were
calculated in the Exposure Assessment (Section 3.2).
The HQ is based on the assumption that there is a level of exposure (i.e., the RfD or RfC)
below which it is unlikely, even for sensitive subgroups, to experience adverse health effects.
Unlike cancer risk, the HQ does not express probability and is not necessarily linear; that is, an
HQ often does not mean that adverse health effects are ten times more likely to occur than for an
HQ of one. However, the ratio of estimated dose to RfD/RfC reflects level of concern.
For chemicals where an RfD or RfC was not available, a MOE was calculated by:
MOE = NOAEL/ADDorLOAEL/ADD
As with the HQ, the MOE is not a probabilistic statement of risk. The ratio for calculating MOE
is the inverse of the HQ, so that a high HQ (exceeding one) indicates a potential concern,
whereas a high MOE (exceeding 100 for a NOAEL-based MOE or 1,000 for a LOAEL-based
MOE) indicates a low concern level. (NOAELS and LOAELs are defined in Section 3.3.2.) As
the MOE increases, the level of concern decreases. (As the HQ increases, the level of concern
also increases.)
Both the exposure estimates and toxicity data are specific to the route of exposure (i.e.,
inhalation, oral, or dermal). Very few RfDs, NOAELs, or LOAELs were available for dermal
exposure. If oral data were available, the following adjustments were made to calculate dermal
values:
RfDDER = (RfDORAL)(GI absorption)
= (NOAEL or LOAELORAL)(GI absorption)
= (SFORAL)/GI absorption)
where:
RfDDER = reference dose adjusted for dermal exposure (mg/kg-day)
NOAEL/LOAELpgR = NOAEL or LOAEL adjusted for dermal exposure (mg/kg-day)
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3.4 RISKC3HARACTERIZATION
SFDER = cancer slope factor adjusted for dermal exposure (mg/kg-day)"1
GI absorption = gastrointestinal absorption efficiency
This adjustment is made to account for the fact that the oral RfDs, NOAELs, and LOAELs are
based on an applied dose, while dermal exposure represents an estimated absorbed dose. The
oral RfDs, NOAELs, and LOAELs used to assess dermal risks were therefore adjusted using
gastro-intestinal (GI) absorption to reflect an absorbed dose. Table 3.35 lists the GI absorption
data used in calculating risk from dermal exposure.
Table 3.35 Absorption Percentages
Chemicals9
1,3-Benzenediol
2-Ethoxyethanol
Ammonium Chloride
Benzotriazole
Boric Acid
Copper (I) Chloride
Diethylene Glycol Ethyl Ether
Diethylene Glycol Methyl Ether
Diethylene Glycol n-Butyl Ether
Dimethylformamide
ithanolamine
Bthylene Glycol
Pluoroboric Acid
Formaldehyde
Hydrogen Peroxide
ftydroxyacetic Acid
Isopropyl Alcohol, 2-Propanol
VIethanol
Palladium
Palladium Chloride
Phenol
Potassium Cyanide
Silver
Sodium Chlorite
Sodium Cyanide
Sodium Sulfate
Stannous Chloride
Vanillin
. GI Tract Absorption
(%)
100
100
97
20
90
60
20
20
20
20
20
100
100
1
5
20
20
100
5
5
20
5
21
5
5
100
3
6
Source of Data
NTP, 1992
assumption11
Reynolds, 1982
assumption13
EPA, 1990
EPA, 1994a
assumption13
assumption11
assumption11
assumption13
assumption15
ATSDR, 1993
Stokinger, 1981
EPA, 1995b
default (EPA, 1989)
assumption11
assumption13
Lington & Bevan, 1994
Beliles, 1994
Beliles, 1994
assumption13
default (EPA, 1989)
ATSDR, 1990b
default (EPA, 1989)
default (EPA, 1989)
HSDB, 1995
ATSDR, 1992
Kirwin and Galvin, 1993
1 Includes only those chemicals where dermal HQs or MOEs were calculated. Proprietary chemical data are not
presented in order to protect proprietary chemical identities.
b An assumption of 20 percent was made for organic chemicals when no other data were available.
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3.4 MSKCHARACTEMZATION
3.4.4 Results of Calculating Risk Indicators
This section presents the results of "calculating risk indicators for both the occupational
setting and the ambient (outdoor) environment. When considering these risk characterization
results, it should be remembered that the results are intended for use in relative risk comparisons
between processes based on a model PWB facility, and should not be used as absolute indicators
for potential health risks to MHC line workers or to the public.
Occupational Setting
Estimated cancer risks and non-cancer risk indicators from occupational exposure to
MHC chemicals are presented below. It should be noted that no epidemiological studies of
health effects among PWB workers were located.
Inhalation Cancer Risk. The electroless copper and graphite processes are the only
processes containing chemicals for which a cancer slope (cancer potency) factor is available.
Formaldehyde, in the electroless copper process, is the only non-proprietary chemical for which
an inhalation cancer risk has been estimated. Formaldehyde has an EPA weight-of-evidence
classification of Group B1, a Probable Human Carcinogen. The EPA Group B1 classification is
typically based on limited evidence of carcinogenicity in humans, sufficient evidence of
carcinogenicity in animals, and additional supporting evidence. The cancer slope factor for
formaldehyde is based exclusively on animal data, and is associated with nasal cancer.
Inhalation exposure estimates are based on the assumptions that emissions to indoor air
from conveyorized lines are negligible, that the air in the process room is completely mixed and
chemical concentrations are constant over time, and that no vapor control devices (e.g., bath
covers) are used in non-conveyorized lines. The exposure estimates use 90th percentile modeled
air concentrations (0.62 mg/m3 for formaldehyde in the non-conveyorized electroless copper
process), which means that, based on the IPC Workplace Practices Questionnaire data and
publicly-available information on bath concentrations, approximately 90 percent of the facilities
are expected to have lower air concentrations and, therefore, lower risks. Using 90th percentile
data is consistent with EPA policy for estimating upper-bound exposures.
With regard to formaldehyde cancer risk, EPA in 1987 issued a risk assessment in which
formaldehyde was classified as a Group Bl Probable Human Carcinogen; in addition it was
determined to be an irritant to the eyes and respiratory tract. A quantitative risk assessment for
cancer was presented using available exposure data and a cancer slope (cancer potency) factor of
0.046 per milligram formaldehyde per kilogram body weight per day. In 1991, EPA proposed a
modification of this assessment using additional animal testing and exposure data that had
become available. Incorporation of this new data would result in an estimated cancer slope factor
of 0.00094 per milligram formaldehyde per kilogram body weight per day, a 50-fold reduction
from the current cancer slope factor. However, EPA's Science Advisory Board recommended
that formaldehyde cancer risk be presented as a range of risk estimates using data from both the
1987 and 1991 assessments, due to the many uncertainties and data gaps that preclude the use of
one assessment to the exclusion of the other. Therefore, upper bound maximum individual
cancer risk over a lifetime is presented as a range from 1 x 10"3 (one in 1,000) to 2 x 10'5 (two in
100,000 or one in 50,000) based on a workplace concentration of 0.62 milligrams formaldehyde
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3.4 RISK CHARACTERIZATION
per cubic meter of air (over an 8 hour-day) for line operators using the non-conveyorized
electroless copper process. It should be pointed out that intensity of exposures to formaldehyde
(air concentration) may be more important than average exposure levels over an 8-hour day in
increasing cancer risk (Hernandez et al., 1994). The use of modeled, steady state, workplace air
concentrations instead of actual monitoring data of average and peak concentrations thus emerges
as a significant source of uncertainty in estimating cancer risk to workers exposed to
formaldehyde La this industry. The available toxicological data do not indicate that dermal
exposure to formaldehyde increases cancer risk, but no dermal cancer studies were located.
To provide further information on the possible variation in occupational formaldehyde
exposure and risk estimates, formaldehyde cancer risk is also estimated using average and
median values, as would be done for a central tendency exposure estimate.14 The following
median or average parameter values are used:
• The 50th percentile air concentration estimated from the quantitative uncertainty analysis
(Section 3.2.3) of 0.055 mg/m3 (compared to the high-end point estimate of 0.62 mg/m3).
• The median job tenure for men in the U.S. of 4.0 years (Bureau of Labor Statistics, 1997)
(compared to the 95th percentile of 25 years).
• The average value of 6.8 hrs/day for a line operator from the IPC Workplace Practices
Questionnaire (compared to the 90th percentile of 8 hrs/day).
• The average exposure frequency of 250 days/year from the IPC Workplace Practices
Questionnaire (compared to the 90th percentile of 306 days/year).
Using these values, there is approximately a 100-fold reduction in estimated exposure with the
estimated "central tendency" LADD of 2.6 x 10'4 mg/kg-day. Combined with the slope factor of
0.046 per mg/kg-day, this results in a cancer risk of 1 x 10"5 (one in 100,000). Considering the
50-fold reduction in cancer potency (with a slope factor of 0.00092 per mg/kg-day) the cancer
risk would be 2 x 10'9 (one in five million).
Inhalation cancer risk was also estimated for one proprietary chemical, alkyl oxide, in the
non-conveyorized electroless copper process. This is discussed to a limited extent, however, to
protect proprietary ingredient identity. The line operator inhalation exposure estimate for alkyl
oxide15 results in an estimated upper bound excess individual lifetime cancer risk of 3 x 10"7
based on high end exposure.
14 This "central tendency" estimate should also be considered a "what-if" exposure estimate, because of the
uncertainty of the process area ventilation rate data.
15 It should be noted that alkyl oxide is present in the electroless copper and graphite baths at trace
concentrations (less than one part per million) and it has a relatively high tendency to evaporate. Based on air
modeling estimates, and assuming 100 liter baths, all of this chemical would be released to air within one hour. The
assumption that chemical concentration in the baths remains constant over time would result, in this case, in large
over-estimates of inhalation exposure. A correction factor was applied to the calculated cancer risks to reflect
exposure from the chemical being present for one hour in the baths, at a yearly frequency equal to the bath
replacement frequency.
.^,_^.•^^^^^^^^^^^^^^•^^^^^^^^•••^^^^^^•••^^^^^^••^•••^^•••••^
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3.4 RISK CHARACTERIZATION
Risks to other workers were assumed to be proportional to the amount of time spent in
the process area. Based on the IPC Workplace Practices Questionnaire data, the average line
operator spends 1,900 hours per year in the MHC process area. Annual average exposure times
(i.e., time spent in the process area) for various worker types from the workplace practices
database are listed below. The number in parenthesis is the ratio of average time for that worker
type to the average time for a line operator.
Contract worker: 62 hours per year (0.033).
Laboratory technician: 1,100 hours per year (0.58).
Maintenance worker: 930 hours per year (0.49).
Supervisor: 1,150 hours per year (0.61).
Wastewater treatment operator: 1,140 hours per year (0.60).
Other: 1,030 hours per year (0.54).
Dermal Cancer Risk. Dermal cancer risks were estimated for two proprietary
chemicals, alkyl oxide and cyclic ether, in the graphite and electroless copper processes. These
results are only discussed to a limited extent, however, in order to protect the identity of the
proprietary ingredients. Both chemicals have oral cancer slope factors, which were converted for
dermal exposure as described in Section 3.4.3. Worker dermal exposure estimates for cyclic
ether result in the following estimated upper bound excess individual lifetime cancer risks:
• For conveyorized electroless copper, 8 x 10"8 for a line operator and 9 x 10"9 for a
laboratory technician.
• For non-conveyorized electroless copper, 4 x 10"7 for a line operator and 9 x 10"9 for a
laboratory technician.
• For graphite, 1 x 10"7 for a line operator and 9 x 10"9 for a laboratory technician.
All of these cancer risk estimates are below the concern level of 1 x 10"6. Worker dermal
exposure estimates for alkyl oxide result in the following estimated upper bound excess
individual lifetime cancer risks:16
• For conveyorized electroless copper, 4 x 10"9 for a line operator and 1 x 10"10 for a
laboratory technician.
• For non-conveyorized electroless copper, 1 x 10"8 for a line operator and 1 x 10"10 for a
laboratory technician.
• For graphite, 8 x 10"8 for a line operator and 6 x 10"9 for a laboratory technician.
Other Potential Cancer Risks. Slope factors (cancer potency values) are needed to
calculate estimates of cancer risk. In addition to the chemicals discussed above,
16 It should be noted that alkyl oxide is present in the electroless copper and graphite baths at trace
concentrations (less than one part per million) and it has a relatively high tendency to evaporate. Based on air
modeling estimates, and assuming 100 liter baths, all of this chemical would be released to air within one hour. The
assumption that chemical concentration in the baths remains constant over time would result in this case, in large
over-estimates of dermal exposure. A correction factor was applied to the calculated cancer risks to reflect exposure
from the chemical being present for one hour in the baths, at a yearly frequency equal to the bath replacement
frequency.
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3.4 RISK CHARACTERIZATION
dimethylformamide and carbon black are classified as probable human carcinogens (IARC Group
2B). Like formaldehyde, the evidence for carcinogenic effects is based on animal data.
However, unlike formaldehyde, slope factors are riot available for either chemical. There are
potential cancer risks to workers from both chemicals, but they cannot be quantified.
Dmethylformamide is used in the electroless copper process. Workplace exposures have been
estimated but cancer potency and cancer risk are unknown. Carbon black is used in the carbon
and conductive ink processes. Occupational exposure due to air emissions from the carbon baths
is expected to be negligible because the carbon process is typically conveyorized and enclosed.
There may be some airborne carbon black, however, from the drying oven steps, which was not
quantified in the exposure assessment. Carbon black is also used in one product line of the
conductive ink process; exposures from conductive ink were not characterized. One proprietary
chemical used in the electroless copper process, trisodium acetate amine B, was determined to
possibly be carcinogenic to humans but does not have an established slope factor.
Non-Cancer Risk. HQs and MOEs for line operators and laboratory technicians from
workplace exposures are presented in Appendix E. An HQ exceeding one indicates a potential
concern. Unlike cancer risk, HQ does not express probability, only the ratio of the estimated
dose to the RfD or RfC, and it is not necessarily linear (an HQ often does not mean that adverse
health effects are ten times more likely than an HQ of one).
EPA considers high MOE values, such as values greater than 100 for a NOAEL-based
MOE or 1,000 for a LOAEL-based MOE, to pose a low level of concern (Barnes and Dourson,
1988). As the MOE decreases, the level of concern increases. Chemicals are noted here to be of
potential concern if a NOAEL-based MOE is lower than 100, a LOAEL-based MOE is lower
than 1,000, or a MOE based on an effect level that was not specified as a LOAEL is less than
1,000. As with HQ, it is important to remember that the MOE is not a probabilistic statement of
risk.
Inhalation risk indicators of concern for non-proprietary chemicals are presented in Table
3.36, and for the known proprietary chemicals in Table 3.37. This includes chemicals of
potential concern based on MOE and/or HQ results, as well as cancer risk results for any
chemical with a cancer slope factor. Inhalation exposure estimates are based on the assumptions
that emissions to air from conveyorized lines are negligible, that the air in the process room is
completely mixed and chemical concentrations are constant over time, and that no vapor control
devices (e.g., bath covers) are used in non-conveyorized lines.
Dermal risk indicators of concern for non-proprietary chemicals are presented in Table
3.38 and for the known proprietary chemicals in Table 3.39. This includes chemicals of potential
concern based on MOE and/or HQ results, as well as cancer risk results for any chemical with a
cancer slope factor. Dermal exposure estimates are based on the assumption that both hands are
routinely immersed in the bath and that the worker does not wear gloves.
It should be noted that Tables 3.36 through 3.39 do not include chemicals for which
toxicity data were unavailable.
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3-115
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3.4 RISK CHARACTERIZATION
Table 3.37 Summary of Human Health Risk Results from Inhalation Exposure for
Selected Proprietary Chemicals
Code Name for
Chemical of
Concern
Alkyl Oxide
Alkene Diol
Risk Indicator
Electroless Copper, non-conveyorized
cancer risk
3 x 10~7, line operator
MOB
97, line operator
LOAEL
Potential Health Effects
Probable human carcinogen.
Exposure to low levels may result in irritation
of the throat and upper respiratory tract.
Note: Baths not specified to protect proprietary chemical identities.
* This table includes results for chemicals and pathways with a MOE less than 1,000 if based on LOAELs (or less
than 100 if based on NOAELs), an HQ greater than one, or a calculated cancer risk. It does not include chemicals
for which toxicity data were unavailable, chemicals which have not been identified or evaluated because of their
proprietary status, or chemicals used in MHC process alternatives which were not included in this evaluation.
* How to read this table:
A: Type of risk indicator for which results are reported (HQ, MOE, or cancer risk)
C: Value calculated for risk indicator (cancer risk, HQ, or MOE).
D: Type of worker for which risk results are presented (line operator or laboratory technician).
E: Type of toxicity data used for MOE: NOAEL, LOAEL or data from human exposures which do not
provide a range of exposures but identify levels which have adverse effects on humans.
0 There is generally a higher level of confidence in the HQ than the MOE because the HQ is based on an RfD or RfC
that has been peer-reviewed by EPA. MOEs are calculated for chemicals without an available RfC or RfD.
For inhalation exposure, 2-ethoxyethanol is the only MHC chemical with an HQ greater
than one; this is for a line operator in the non-conveyorized electroless copper process.
Chemicals with MOEs below the above-mentioned levels for inhalation exposure include the
following:
• For non-conveyorized electroless copper: copper (I) chloride, ethanolamine, ethylene
glycol, formaldehyde, formic acid, methanol, sodium hydroxide, sulfuric acid, and one
proprietary chemical for a line operator.
• For non-conveyorized tin-palladium: ethanolamine and sulfuric acid for a line operator.
• For non-conveyorized non-formaldehyde electroless copper: sulfuric acid for a line
operator.
Dermal risk indicators of concern for non-proprietary chemicals are presented in Table
3.38 and for the known proprietary chemicals in Table 3.39. Dermal exposure estimates are
based on the assumption that workers do not wear gloves and that all non-conveyorized lines are
operated by manual hoist. Chemicals with HQs from dermal exposure greater than one include:
• Formaldehyde for a line operator in the non-conveyorized electroless copper and
conveyorized electroless copper processes.
• Stannous chloride for a line operator in the non-conveyorized electroless copper, non-
formaldehyde electroless copper (non-conveyorized), non-conveyorized tin-palladium,
and conveyorized tin-palladium processes.
• One proprietary chemical for a line operator in the conveyorized electroless copper
process.
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3.4 mSK CHARACTERIZATION
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3.4 RISK CHARACTERIZATION
Chemicals with NOAEL-based MOEs lower than 100, or LOAEL-based MOEs or other MOEs
lower than 1,000 for dermal exposure include the following:
• For non-conveyorized electroless copper: copper (I) chloride, fluoroboric acid,
palladium, sodium chlorite, and two proprietary chemicals for a line operator; copper (I)
chloride, fluoroboric acid, and palladium for a laboratory technician.
• For conveyorized electroless copper: copper (I) chloride, fluoroboric acid, palladium,
sodium chlorite, and two proprietary chemicals for a line operator; copper (I) chloride,
fluoroboric acid, and palladium for a laboratory technician.
• For non-conveyorized non-formaldehyde electroless copper: sodium chlorite for a line
operator.
• For non-conveyorized tin-palladium: copper (I) chloride, fluoroboric acid, palladium and
palladium chloride for a line operator and laboratory technician.
• For conveyorized tin-palladium: copper (I) chloride, fluoroboric acid, palladium and
palladium chloride for a line operator and laboratory technician.
• For non-conveyorized organic-palladium: one proprietary chemical for a line operator
and laboratory technician.
• For conveyorized organic-palladium: one proprietary chemical for a line operator and
laboratory technician.
Ambient (Outdoor) Environment
Cancer Risk. As with the occupational setting, the electroless copper and graphite
processes are the only processes for which a cancer risk to humans in the ambient (outdoor)
environment has been estimated. Formaldehyde is the only non-proprietary chemical with cancer
risks estimated for the general population. These results are for both conveyorized and non-
conveyorized electroless copper processes, assuming that emissions from both process
configurations are vented to the outside. The upper bound excess17 individual lifetime cancer
risk for nearby residents from the non-conveyorized electroless copper process from
formaldehyde inhalation was estimated to range from 2 x 10"9 to 1 x 10'7. The risk for nearby
residents from the conveyorized electroless copper process was estimated to range from 6 x 10'9
to 3 x 10"7. Again, the higher values (3 x 10'7 for conveyorized and 1 x 10"7 for non-
conveyorized) are based on a LADDs of 7.0 x 10'6 mg/kg-day and 2.6 x 10"6 mg/kg-day,
respectively, and a slope (cancer potency) factor of 0.046 per mg/kg-day. The lower values
(6 x 10"9 for conveyorized and 2 x 10"9 for non-conveyorized) take into account a possible 50-fold
reduction in inhalation unit risk.
The discussion of reduction in estimated cancer risk from Section 3.4.1 applies to these
results as well. Formaldehyde has been classified as Group Bl, a Probable Human Carcinogen
based on limited evidence of carcinogenicity in humans, sufficient evidence of carcinogenicity in
animals, and additional supportive evidence. These estimates indicate low concern and are
17 Upper bound refers to the method of determining a slope factor, where the upper bound value (generated
from a certain probability statement) for the slope of the dose-response curve is used. Excess means the estimated
cancer risk is in addition to the already-existing background risk of an individual contracting cancer from all other
causes.
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3.4 RISK CHARACTERIZATION
interpreted to mean that, over a lifetime, an individual resident is expected to have no more than
one excess chance in ten million of developing cancer from exposure to formaldehyde from a
nearby facility using the non-conveyorized electroless copper process, or one excess chance in
three million of developing cancer from exposure to formaldehyde from the conveyorized
electroless copper process. The conveyorized electroless copper risk is slightly higher due to the
larger surface areas of conveyorized baths, resulting in higher modeled air emission rates.
The graphite and electroless copper processes contain one known proprietary chemical,
alkyl oxide, with an inhalation cancer slope factor. Inhalation exposure to cyclic ether, the other
proprietary chemical with a cancer slope factor, is assumed negligible because the chemical is
non-volatile and is not used in an air-sparged bath. The upper bound excess individual lifetime
cancer risk for nearby residents from the (conveyorized) graphite process from inhalation of alkyl
oxide was estimated to be 9 x 10"11. This estimate indicates low concern and is interpreted to
mean that, over a lifetime, an individual resident is expected to have no more than one excess
chance in 11 billion of developing cancer from exposure to alkyl oxide from a conveyorized
graphite process. The upper bound excess individual lifetime cancer risk for nearby residents
from the electroless copper process from inhalation of alkyl oxide was estimated to be 1 x 10"11
for the non-conveyorized process and 3 x 10"11 for the conveyorized electroless copper process.18
These estimates also indicate low concern and are interpreted to mean that, over a lifetime, an
individual resident is expected to have no more than one excess chance of developing cancer in
100 billion for non-conveyorized electroless copper, and no more than one excess chance in 33
billion for conveyorized electroless copper from inhalation exposure to alkyl oxide.
None of the other process alternatives use chemicals for which cancer slope factors were
available, so no other cancer risks were estimated. Other identified chemicals in the MHC
processes are suspected carcinogens, but do not have established slope factors.
Dimethylformamide and carbon black have been determined by IARC to possibly be
carcinogenic to humans (IARC Group 2B). Dimethylformamide is used in the electroless copper
process. Carbon black is used in the carbon and conductive ink processes. Carbon black is not
expected to be released to outside air in any significant amount from a facility using the carbon
process. This is because carbon black is not a volatile compound, and aerosol releases are not
expected because it is not used in an air-sparged bath. Conductive ink exposures and risks were
not characterized. One proprietary chemical used in the electroless copper process, trisodium
acetate amine B, was determined to possibly be carcinogenic to humans but does not have an
established slope factor.
Non-Cancer Risk. Appendix E presents HQs for estimated chemical releases to ambient
air, and subsequent inhalation by residents near a model facility. Chemicals below the emission
rate cutoff of 23 kg/year are not included because below this emission rate exposures are
18 It should be noted that alkyl oxide is present in the electroless copper and graphite baths at trace
concentrations (less than one part per million) and it has a relatively high tendency to evaporate. Based on air
modeling estimates, and assuming 100 liter baths, all of this chemical would be released to air within one hour. The
assumption that chemical concentration in the baths remains constant over time would result, in this case, in large
over-estimates of inhalation exposure. A correction factor was applied to the calculated cancer risks to reflect
exposure from the chemical being present for one hour in the baths, at a yearly frequency equal to the bath
replacement frequency.
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3.4 RISK CHARACTERIZATION
expected to be negligible. All HQs are less than one for ambient exposure to the general
population, indicating low concern.
These results suggest there is low risk to nearby residents, based on incomplete but best
available data. Data limitations include the use of modeled air concentrations using average data
rather than site-specific, measured concentrations. For estimating ambient (outdoor) air
concentrations, one key assumption is that no air pollution control technologies are used to
remove airborne chemicals from facility air prior to venting it to the outside. Other data
limitations are the lack of waterborne and solid waste data to characterize exposure routes in
addition to inhalation, and lack of toxicity data for many chemicals.
Appendix E presents MOEs from ambient air exposures. The chemicals included are
those above the emission rate cutoff and for which NOAEL or LOAEL data were available.
(Also if an HQ could be calculated an MOE was not.) All MOEs for ambient exposure are
greater than 1,000 for all processes, indicating low concern from the estimated air concentrations.
3.4.5 Uncertainties
An important component of any risk characterization is the identification and discussion
of uncertainties. There are uncertainties involved in the measurement and selection of hazard
data, and in the data, models and scenarios used in the Exposure Assessment. Any use of the risk
characterization should include consideration of these uncertainties.
Uncertainties in the Exposure Assessment include the following:
• Accuracy of the description of exposure setting: how well the model facility used in the
assessment characterizes an actual facility; the likelihood of exposure pathways actually
occurring (scenario uncertainty).
• Missing data and limitations of workplace practices data: this includes possible effects of
any chemicals that may not have been included (e.g., minor ingredients in the
formulations, proprietary chemical identities not disclosed by suppliers); possible effects
of side reactions in the baths which were not considered; and questionnaire data with
limited facility responses.
• Estimating exposure levels from averaged data and modeling in the absence of measured,
site-specific data.
• Data limitations in the Source Release Assessment: releases to surface water and land
could not be characterized quantitatively.
• Chemical fate and transport model applicability and assumptions: how well the models
and assumptions represent the situation being assessed and the extent to which the models
have been validated or verified (model uncertainty).
• Parameter value uncertainty, including measurement error, sampling (or survey) error,
parameter variability, and professional judgement.
Key assumptions made in the Exposure Assessment are discussed in Section 3.4.1.
Uncertainties in the hazard data (typically encountered in a hazard assessment) include
the following:
^__^^^^_—^^^^^—••^^^^^^^^^^^^^•••••^^•••^^^^••^••^^••••••^^••«
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3.4 RISK CHARACTERIZATION
Using dose-response data from high dose studies to predict effects that may occur at low
levels.
Using data from short-term studies to predict the effects of long-term exposures.
Using dose-response data from laboratory animals to predict effects in humans.
Using data from homogeneous populations of laboratory animals or healthy human
populations to predict the effects on the general human population, with a wide range of
sensitivities. (This uncertainty is due to natural variations in human populations.)
Using LO AELs and NOAELs in the absence of peer-reviewed RfDs and RfCs.
Possible increased or decreased toxicity resulting from chemical interactions.
Assuming a linear dose-response relationship for cancer risk (in this case for
formaldehyde).
Effects of chemical mixtures not included in toxicity testing (effects may be independent,
additive, synergistic, or antagonistic).
Possible effects of substances not evaluated because of a lack of chronic/subchronic
toxicity data.
Another source of uncertainty comes from use of structure-activity relationships (SARs)
for estimating human health hazards in the absence of experimental toxicity data. Specifically,
this was done for: dimethylaminoborane, EDTA (sodium salt), fluoroboric acid, graphite,
magnesium carbonate, m-nitrobenzene sulfonic acid, monopotassium peroxymonosulfate,
palladium chloride, phosphoric acid, potassium bisulfate, potassium carbonate, potassium
persulfate, potassium sulfate, p-toluene sulfonic acid, sodium bisulfate, sodium hypophosphite,
and sodium persulfate. SARs were also used for ten proprietary chemicals.
Uncertainties in assessing risk from dermal exposure come from the use of toxicological
potency factors from studies with a different route of exposure than the one under evaluation
(i.e., using oral toxicity measures to estimate dermal risk). This was done for nine chemicals
with oral RfDs, 15 chemicals with oral NO AELs (as noted in Tables 3.25 and 3.26), and two
proprietary chemicals with oral cancer slope factors. Uncertainties in dermal risk estimates also
stem from the use of default values for missing gastrointestinal absorption data. Specifically, this
was done for benzotriazole, diethylene glycol ethyl ether, diethylene glycol n-butyl ether,
ethanolamine, 2-ethoxyethanol, hydrogen peroxide, hydroxyacetic acid, isopropyl alcohol,
potassium cyanide, sodium chlorite, and sodium cyanide.
Finally, the risk characterization does not address the potential adverse health effects
associated with acute exposure to peak levels of chemicals. This type of exposure is especially
important when evaluating developmental risks associated with exposure.
3.4.6 Conclusions
This risk characterization uses a health-hazard based framework and a model facility
approach to compare the health risks of one MHC process technology to the risks associated
which switching to an alternative technology. As much as possible, reasonable and consistent
assumptions are used across alternatives. Data to characterize the model facility and exposure
patterns for each process alternative were aggregated from a number of sources, including PWB
shops in the U.S. and abroad, supplier data, and input from PWB manufacturers at project
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3.4 RISK CHARACTERIZATION
meetings. Thus, the model facility is not entirely representative of any one facility, and actual
risk could vary substantially, depending on site-specific operating conditions and other factors.
When using the results of this risk characterization to compare health effects among
alternatives, it is important to remember that this is a screening level rather than a comprehensive
risk characterization, both because of the predefined scope of the assessment and because of
exposure and hazard data limitations. It should also be noted that this approach does not result in
any absolute estimates or measurements of risk, and even for comparative purposes, there are
several important uncertainties associated with this assessment.
Primary among these uncertainties is the incoMplete identification of all chemicals among
the process alternatives because of trade secret considerations. This factor alone precludes any
definitive recommendations among the processes because the health risks from all relevant
chemicals could not be evaluated. It should be noted here also that chemical suppliers to the
PWB industry are in the sole position to fill these data gaps for a more complete assessment.19
Without that, conclusions can only be drawn based on the best available information. It should
also be noted that chemical suppliers are required to report on an MSDS (under 29 CFR Part
1910.1200) that a product contains hazardous chemicals, if present at one percent or greater of a
product composition, or 0.1 percent or greater for carcinogens. The chemical manufacturer may
withhold the specific chemical identity from the MSDS, provided that the MSDS discloses the
properties and effects of the hazardous chemical. A review of the available MSDSs indicates
that there are hazardous chemicals listed as trade secret ingredients: three in electroless copper,
one in graphite, three in organic-palladium, and one in tin-palladium. Section 2.1.4 presents
these results and discusses the use of MSDS information further.
Another significant source of uncertainty is the limited data available for dermal toxicity
and the use of oral to dermal extrapolation when dermal toxicity data were unavailable. There is
high uncertainty in using oral data for dermal exposure and in estimating dermal absorption rates,
which could result in either over- or under-estimates of exposure and risk.
A third significant source of uncertainty is from the use of structure-activity relationships
to estimate toxicity in the absence of measured toxicity data, and the lack of peer-reviewed
toxicity data for many MHC chemicals. Other uncertainties associated with the toxicity data
include the possible effects of chemical interactions on health risks, and extrapolation of animal
data to estimate human health risks from exposure to formaldehyde and other PWB chemicals.
19 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project. Atotech provided information on one proprietary ingredient. W.R. Grace was
preparing to transfer information on proprietary chemical ingredients in the conductive ink technology when it was
determined that this information was no longer necessary because risk from the conductive ink technology could not
be characterized. The other suppliers participating in the project (Enthone-OMI, MacDennid, and Shipley) declined
to provide proprietary information on their MHC technologies. The absence of information on proprietary chemical
ingredients is a significant source of uncertainty in the risk characterization. Risk information for proprietary
ingredients, as available, is presented in this CTSA, but chemical identities, concentrations, and chemical properties
are not listed.
•-^^^^^^^^-^.^^^^^^^^••^^^^^^^^^^^^^^^^^^^^^^••^^••••^^^^•••^^^^^^^^••^^^^•••^•••••^
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3.4 RISKCHARACTERIZATIO1S1
Another major source of uncertainty in estimating exposure is the reliance on modeled
data (i.e., modeled air concentrations) to estimate worker exposure. It should also be noted that
there is no comparative evaluation of the severity of effects for which HQs and MOEs are
reported.
The Exposure Assessment for this risk characterization used, whenever possible, a
combination of central tendency and high-end assumptions, as would be used for an overall high-
end exposure estimate. Some values used in the exposure calculations, however, are better
characterized as "what-if," especially pertaining to bath concentrations, use of gloves, and
process area ventilation rates for a model facility. Because some part of the exposure assessment
for both inhalation and dermal exposures qualifies as a "what-if descriptor, the entire
assessment should be considered "what-if."
Among those health risks evaluated, it can be concluded that alternatives to the non-
conveyorized electroless copper process appear to present a lower overall risk, due to reduced
cancer risk to PWB workers when the use of formaldehyde is eliminated. Other adverse effects
from chronic, low level exposures to chemicals in the alternative processes provide some basis
for additional comparison. While alternatives to electroless copper appear to pose less overall
risk, there is insufficient information to compare these alternatives among themselves to
determine which of the alternatives pose the least risk.
Occupational Exposures and Risks
Health risk to workers are estimated for inhalation exposure to vapors and aerosols from
MHC baths and for dermal exposure to MHC bath chemicals. Inhalation exposure estimates are
based on the assumptions that emissions to indoor air from conveyorized lines are negligible, that
the air in the process room is completely mixed and chemical concentrations are constant over
time, and that no vapor control devices (e.g., bath covers) are used in non-conveyorized lines.
Dermal exposure estimates are based on the assumption that workers do not wear gloves and that
all non-conveyorized lines are operated by manual hoist. Dermal exposure to line operators on
non-conveyorized lines is estimated for routine line operation and maintenance (e.g., bath
replacement, filter replacement, etc.), and on conveyorized lines for bath maintenance activities
alone.
Risk results indicate that alternatives to the non-conveyorized electroless copper process
pose lower occupational risks. However, in addition to several chemicals in the non-
conveyorized electroless copper process,lihere are occupational inhalation risk concerns for some
chemicals in the non-formaldehyde electroless copper and tin-palladium non-conveyorized
processes as well. There are also occupational risk concerns for dermal contact with some
chemicals in the electroless copper, organic-palladium, and tin-palladium processes for either
conveyorized or non-conveyorized equipment.
Cancer Risk. The non-conveyorized electroless copper process contains the only non-
proprietary chemical for which an occupational cancer risk has been estimated (for
formaldehyde). Formaldehyde has been classified by EPA as Group Bl, a Probable Human
Carcinogen. The upper bound excess individual cancer risk estimate for line operators in the
non-conveyorized electroless copper process from formaldehyde inhalation may be as high as
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3.4 RISK CHARACTERIZATION
one in a thousand, but may be 50 times less, or one in 50,000.20 Risks to other workers were
assumed to be proportional to the amount of time spent in the process area, which ranged from
three to 61 percent of the risk for a line operator.
Inhalation cancer risk was also estimated for one proprietary chemical, alkyl oxide, in the
non-conveyorized electroless copper process. The line operator inhalation exposure estimate for
alkyl oxide results in an estimated upper bound excess individual life time cancer risk of 3 x 10"7
(one in three million) based on high end exposure. Cancer risks less than 1 x 10"6 (one in one
million) are generally considered to be of low concern.
Additionally, dermal cancer risks were estimated for two proprietary chemicals, cyclic
ether and alkyl oxide, in the graphite and electroless copper processes. For the conveyorized
graphite process, the dermal cancer risks for a line operator may be as high as 8 x 10"8 (about one
in ten million) for the alkyl oxide and 1 x 10"7 (one in ten million) for the cyclic ether. The upper
bound cancer risks for a laboratory technician were much less than the risks for a line operator.
The cancer risks for a laboratory technician were 6 x 10"9 (one in 200 million) for alkyl oxide and
9 x 10"9 (one hi 100 million) for cyclic ether.
For non-conveyorized electroless copper, the dermal cancer risks for the line operator
may be as high as 4 x 10"7 (one in two million) for cyclic ether and 1 x 10"8 (one in 100 million)
for alkyl oxide. The estimated upper bound cancer risks for a laboratory technician were much
less than the cancer risk for a line operator. The estimated cancer risks for a laboratory
technician were 9 x 10"9 (one in 100 million) for cyclic ether and 1 x 10'10 (one in ten billion) for
alkyl oxide.
For conveyorized electroless copper, the dermal cancer risk for a line operator may be as
high as 8 x 10"8 (about one in ten million) for cyclic ether and 4 x 10"9 (one in 200 million) for
alkyl oxide. The estimated upper bound cancer risks for a laboratory technician were much less
than the cancer risks for a line operator. The estimated cancer risks for a laboratory technician
were 9 x 10'9 (one hi 100 million) for cyclic ether and 1 x 10"10 (one in ten billion) for alkyl
oxide.
Other identified chemicals in the MHC processes are suspected carcinogens.
Dimethylformarnide and carbon black have been determined by IARC to possibly be
carcinogenic to humans (IARC Group 2B). Also, a proprietary trisodium acetate amine has been
classified as a possible human carcinogen. Dimethylformarnide and the proprietary chemical are
used in the electroless copper process and carbon black is used in the carbon and conductive ink
processes. There are potential cancer risks to workers from these chemicals, but because there
are no slope factors, the risks cannot be quantified.
20 To provide further information on the possible variation of formaldehyde exposure and risk, an
additional exposure estimate is provided using average and median values (rather than high-end) as would be done
for a central tendency exposure estimate. This results in approximately a 100-fold reduction in occupational
formaldehyde exposure and risk.
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3.4 MSK CHARACTERIZATION
Non-Cancer Risk. For non-cancer risk, HQs greater than one were estimated for
occupational exposures to chemicals hi the non-conveyorized and conveyorized electroless
copper processes, the non-conveyorized and conveyorized tin-palladium processes, and the non-
conveyorized non-formaldehyde electroless process. Also, several chemicals had estimated
MOEs lower than 100 or LOAEL-based MOEs lower than 1,000 for occupational exposures in
the non-conveyorized and conveyorized electroless copper processes, non-conveyorized and
conveyorized tin-palladium processes, non-conveyorized and conveyorized organic-palladium
processes, and non-conveyorized non-formaldehyde electroless copper process.
Based on calculated occupational exposure levels, there may be adverse health effects to
workers exposed to these chemicals with a HQ exceeding 1.0 or an MOE less than 100 or 1,000.
However, it should be emphasized that these conclusions are based on screening level estimates.
These numbers are used here for relative risk comparisons between processes, and should
not be used as absolute indicators for potential health risks to MHC line workers.
Ambient (Outdoor) Exposures and Risks
Public health risk was estimated for inhalation exposure for the general populace living
near a facility. Public exposure estimates are based on the assumption that emissions from both
conveyorized and non-conveyorized process configurations are vented to the outside. The risk
indicators for ambient exposures to humans, although limited to airborne releases, indicate low
concern for nearby residents. The upper bound excess individual cancer risk for nearby residents
from formaldehyde in the non-conveyorized electroless copper process was estimated to be from
approaching zero to 1 x 10"7 (one in ten million) and from approaching zero to 3 x 10"7 (one in
three million) for the conveyorized electroless copper process. Formaldehyde has been classified
by EPA as Group B1, a Probable Human Carcinogen. The upper bound excess individual cancer
risk for nearby residents from the proprietary alkyl oxide in the conveyorized graphite process
was estimated to be from approaching zero to 9 x 10"11 (one in 11 billion); in the non-
conveyorized electroless copper process from approaching zero to 1 x 10"11 (one in 100 billion),
and in the conveyorized electroless copper process from approaching zero to 3 x 10"11 (one in
33 billion). All hazard quotients are less than one for ambient exposure to the general
population, and all MOEs for ambient exposure are greater than 1,000 for all processes,
indicating low concern from the estimated air concentrations for chronic non-cancer effects.
Ecological Hazards
The CTSA methodology typically evaluates ecological risk in terms of risks to aquatic
organisms in streams that receive treated or untreated effluent from manufacturing processes.
Stream concentrations were not available, however, and could not be estimated because of data
limitations (i.e., insufficient characterization of constituents and their concentrations in facility
wastewater). The upper limit of the aquatic release (and thus, its consequent exposure/risk) is
controlled by regulation; the degree of control varies by site. Section 4.3, Regulatory Status,
discusses the pertinent regulations. Because exposure (i.e., stream concentrations) could not be
quantified, ecological (aquatic) risk is not characterized. Instead, an ecological hazard
assessment was performed (Section 3.3.3), based only on chemical toxicity to aquatic organisms.
The results of this evaluation are summarized briefly here.
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3.4 RISK CHARACTERIZATION
Concern concentrations were estimated for MHC chemicals using an established EPA
method. A CC is an acute or chronic toxicity value divided by an assessment factor (AsF). AsFs
are dependent on the amount and type of toxicity data contained in a toxicity profile and reflect
the amount of uncertainty about the potential effects associated with a toxicity value. CCs were
determined for aquatic species (e.g., Daphnia, algae, and/or fish). The lowest,CC is for copper
sulfate, based on fish toxicity data.
Chemicals are also ranked for aquatic toxicity concern levels using established EPA
criteria (high, moderate, and low concern) based on the available toxicity data. The number of
chemicals with a high aquatic hazard concern level include nine in the electroless copper process,
two in carbon, two in conductive ink, none in conductive polymer, three in graphite, three in non-
formaldehyde electroless copper, two in organic-palladium, and nine in the tin-palladium
process.
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3.5 PROCESS SAFETY ASSESSMENT
3.5 PROCESS SAFETY ASSESSMENT
Process safety is the concern of employers and employees alike. Each company has the
obligation to provide its employees with a safe and healthy work environment, while each
employee is responsible for his/her own safe personal work habits. An effective process safety
program identifies potential workplace hazards and, if possible, seeks to eliminate or at least
reduce their potential for harm. In the MHC process of PWB manufacturing, these hazards may
be either chemical hazards or process hazards. Chemicals used in the MHC process can be
hazardous to worker health and therefore must be handled and stored properly, using appropriate
personal protective equipment and safe operating practices. Automated equipment can be
hazardous to employees if safe procedures for cleaning, maintaining, and operating are not
established and regularly performed. These hazards can result in serious injury and health
problems to employees, and potential damage to equipment.
The U.S. Department of Labor and the Occupational Safety and Health Administration
(OSHA) have established safety standards and regulations to assist employers in creating a safe
working environment and protect workers from potential workplace hazards. In addition,
individual states may also have safety standards regulating chemical and physical workplace
hazards for many industries. Federal safety standards and regulations affecting the PWB industry
can be found in the Code of Federal Regulation (CFR) Title 29, Part 1910 and are available by
contacting your local OSHA field office. State and local regulations are available from the
appropriate state office. This section of the CTSA presents chemical and process safety concerns
associated with the MHC baseline and substitutes, as well as OSHA requirements to mitigate
these concerns.
3.5.1 Chemical Safety Concerns
As part of its mission, OSHA's Hazard Communication Standard (29 CFR 1910.1200)
requires that chemical containers be labeled properly with chemical name and warning
information [.1200(f)], that employees be trained in chemical handling and safety procedures
[.1200(h)], and that a MSDS be created and made available to employees for every chemical or
formulation used in the workplace [.1200(g)]. Each MSDS must be in English and include
information regarding the specific chemical identity of the hazardous chemical(s) involved and
the common names. In addition, information must be provided on the physical and chemical
characteristics of the hazardous chemical; known acute and chronic health effects and related
health information; exposure limits; whether the chemical is a carcinogen; emergency and first-
aid procedures; and the identification of the organization preparing the data sheet. Copies of
MSDSs for all of the chemicals used must be kept and made available to workers who may come
into contact with the process chemicals during their regular work shift.
In order to evaluate the chemical safety concerns of the various MHC processes, MSDSs
for 172 chemical products comprising eight MHC technology categories were collected and
reviewed for potential hazards to worker safety. The results of that review are summarized and
discussed in the categories below. General information on OSHA storage and handling
requirements for chemicals in these hazard categories are located in the process safety section of
this chapter. For a more detailed description of OSHA storage and handling requirements for
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3.5 PROCESS SAFETY ASSESSMENT
MHC chemical products in these categories contact your area OSHA field office or state
technical assistance program for assistance.
Flammable. Combustible, and Explosive MHC Chemical Products
A breakdown of MHC chemical products that when in concentrated form are flammable,
combustible, explosive, or pose a fire hazard is presented in Table 3.40. The following lists
OSHA definitions for chemicals in these categories, and discusses the data presented in the table.
Table 3.40 Flammable, Combustible, Explosive, and Fire Hazard Possibilities
for MHC Processes
MHC Process
Carbon
Conductive Ink
Conductive Polymerb
Electroless Copper
Graphite
Non-Formaldehyde
Electroless Copper
Palladium
Bath Type
Cleaner
Conditioner
Other (Anti-Tarnish)
Print Ink
Polymer
Accelerator
Anti-Tarnish
Cleaner/Conditioner
Electroless Copper
Microetch
Microetch
Accelerator
Anti-Tarnish
Microetch
Accelerator
Cleaner/Conditioner
Other (Anti-Tarnish)
Hazardous Property*
Flammable
2(2)
3(3)
2(2)
1(3)
1(5)
2(4)
1(8)
2(25)
1(9)
1(2)
1(1)
1(4)
1(6)
1(3)
Combustible
1(25)
1(6)
Explosive
5(5)
1(8)
1(10)
Fire Hazard
1(25)
1(4)
1(10)
Table entries are made in the following format - # of products meeting OSHA definition for the given hazardous
property as reported in the products MSDSs (Total # of products in the process bath). A blank entry means that
none of the products for the specific process bath meet the OSHA reporting criteria for the given property.
Example: For the palladium process accelerator bath, 1 (10) means that one of the ten products in the bath were
classified as explosive per OSHA criteria as reported on the products MSDSs.
b Hazardous properties based on German equivalent of MSDS, which may not have same reporting requirements of
U.S. MSDS.
Flammable - A flammable chemical is defined by OSHA [29 CFR 1910.1200(c)] as one of the
following:
• An aerosol that, when tested by the method described in 16 CFR 1500.45, yields a flame
projection exceeding 18 inches at full valve opening, or a flashback at any degree of valve
opening.
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3.5 PROCESS SAFETY ASSESSMENT
• A gas that has: 1) at ambient temperature and pressure, forms a flammable mixture with
air at a concentration of 13 percent by volume or less; or 2) when it, at ambient
temperature and pressure, forms a range of flammable mixtures with air wider than 12
percent by volume, regardless of the lower limit.
• A liquid that has a flashpoint below 100 °F (37.8 °C), except any mixture having
components with flashpoints of 100 °F (37.8 °C) or higher, the total of which make up 99
percent or more of the total volume of the mixture.
• A solid, other than a blasting agent or explosive as defined in 29 CFR 1910.109(a), that is
liable to cause fire through friction, absorption of moisture, spontaneous chemical
change, or retained heat from manufacturing or processing, or which can be ignited
readily and when ignited burns so vigorously and persistently as to create a serious
hazard.
Twenty chemical products are reported as flammable according to MSDS data. While all
of the products have flashpoints near or below 100 °F, several of the products reported as
flammable have flashpoints greater than 200 °F with one as high as 400 °F. Although several
chemical products are flammable in their concentrated form, most chemical baths in the MHC
process line contain non-flammable aqueous solutions.
Combustible Liquid - As defined by OSHA [29 CFR 1910.1200(c)], a liquid that is considered
combustible has a flashpoint at or above 100 °F (37.8 °C), but below 200 °F (93.3 °C), except
any mixture having components with flashpoints of 200 °F (93.3 °C), or higher, the total volume
of which make up 99 percent or more of the total volume of the mixture. Two chemical products
have been reported as combustible by their MSDSs, both with flashpoints above 155 °F.
Explosive - As defined by OSHA [29 CFR 1910.1200(c)], a chemical is considered explosive if
it causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to
sudden shock, pressure, or high temperature. Seven chemical products are reported as explosive
by their MSDSs.
Fire Hazard - A chemical product that is a potential fire hazard is required by OSHA to be
reported on the product's MSDS. According to MSDS data, three chemical products are reported
as potential fire hazards.
3.5.2 Corrosive, Oxidizer, and Reactive MHC Chemical Products
A breakdown of MHC chemical baths containing chemical products that are corrosive,
oxidizers, or reactive in their concentrated form is presented in Table 3.41. The table also lists
process baths that contain chemical products that may cause a sudden release of pressure when
opened. The following lists OSHA definitions for chemicals in these categories and discusses
the data presented in the table.
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3.5 PROCESS SAFETY ASSESSMENT
Table 3.41 Corrosive, Oxidizer, Reactive, Unstable, and Sudden Release of Pressure
Possibilities for MHC Processes
MHC Process
Carbon
Conductive
Polymer1"
Electroless Copper
Graphite
Non-Formaldehyde
Electroless Copper
Palladium
Bath Type
Cleaner
Conditioner
Microetch
Catalyst
Conductive Polymer
Microetch
Accelerator
Catalyst
Cleaner/Conditioner
Electroless Copper
Microetch
Predip
Fixer
Graphite
Microetch
Accelerator
Electroless Copper
Microetch
Accelerator
Catalyst
Cleaner/Conditioner
Microetch
Other
Predip
Hazardous Property"
Corrosive
2(2)
3(3)
2(3)
2(3)
1(1)
1(5)
5(10)
5(8)
11(25)
3(9)
4(6)
1(1)
1(3)
2(4)
2(6)
2(4)
4(10)
4(9)
1(6)
2(3)
1(4)
Oxidizer
2(2)
1(5)
5(9)
1(4)
1(2)
2(4)
Reactive
2(2)
3(5)
2(10)
2(8)
5(25)
2(9)
2(6)
1(2)
1(6)
2(4)
1(10)
1(9)
1(5)
Unstable
1(9)
1(4)
1(5)
Sudden Release
of Pressure
1(9)
1(4)
Table entries are made in the following format - # of products meeting OSHA definition for the given hazardous
property as reported in the product's MSDSs (Total # of products in the process bath). A blank entry means that
none of the products for the specific process bath meet the OSHA reporting criteria for the given property.
Example: For the graphite process microetch bath, 2 (4) means that two of the four products in the bath were
classified as corrosive per OSHA criteria as reported by the products MSDSs.
b Hazardous properties based on German equivalent of MSDS, which may not have same reporting requirements of
U.S. MSDS.
Corrosive - As defined by OSHA (29 CFR 1910.1200 [Appendix A]), a chemical is considered
corrosive if it causes visible destruction of, or irreversible alterations in, living tissue by chemical
action at the site of contact, as determined by the test method described by the U.S. Department
of Transportation 49 CFR Part 173 Appendix A. This term does not apply to chemical action on
inanimate surfaces. A review of MSDS data found that 59 MHC chemical products are reported
as corrosive in their concentrated form. Some MHC baths may also be corrosive, but MSDSs do
not provide data for the process chemical baths once they are prepared.
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3.5 PROCESS SAFETY ASSESSMENT
Oxidizer - As defined by OSHA (29 CFR 1910.1200[c]), an oxidizer is a chemical other than a
blasting agent or explosive as defined by OSHA [29 CFR 1910.109(a)], that initiates or promotes
combustion in other materials, thereby causing fire either of itself or through the release of
oxygen or other gases. Twelve chemical products are reported as oxidizers according to MSDS
data.
Reactive - A chemical is considered reactive if it is readily susceptible to change and the possible
release of energy. EPA gives a more precise definition of reactivity for solid wastes. As defined
by EPA (40 CFR 261.23), a solid waste is considered reactive if it exhibits any of the following
properties: 1) is normally unstable and readily undergoes violent change without detonating; 2)
reacts violently or forms potentially explosive mixtures with water; 3) when mixed with water,
generates toxic gases, vapors, or fumes in a quantity that can present a danger to human health or
the environment (for a cyanide or sulfide bearing waste, this includes exposure to a pH between 2
and 12.5); 4) is capable of detonation or explosive reaction if subjected to a strong initiated
source or if heated under confinement; or 5) is readily capable of detonation or explosive
decomposition or reaction at standard temperature and pressure. A review of MSDS data found
that 25 chemical products from four different MHC processes are considered reactive.
Unstable - As defined by OSHA (29 CFR 1910.1200[c]), a chemical is unstable if in the pure
state, or as produced or transported, will vigorously polymerize, decompose, condense, or will
become self-reactive under conditions of shock, pressure, or temperature. Only three chemical
products are reported as unstable according to MSDS data.
Sudden Release of Pressure - OSHA requires the reporting of chemical products that, while
stored in a container subjected to sudden shock or high temperature, causes a pressure increase
within the container that is released upon opening. MSDS data indicated only two chemical
products that are potential sudden release of pressure hazards.
3.5.3 MHC Chemical Product Health Hazards
A breakdown of MHC process baths that contain chemical products that are sensitizers,
acute or chronic health hazards, or irreversible eye damage hazards in their concentrated form is
presented in Table 3.42. Also discussed in this section are MHC chemical products that are
potential eye or dermal irritants and suspected carcinogens. The following presents OSHA
definitions for chemicals in these categories and discusses the data in Table 3.42 where
appropriate. ;
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3.5 PROCESS SAFETY ASSESSMENT
Table 3.42 Sensitizer, Acute and Chronic Health Hazards, and Irreversible Eye Damage
Possibilities for MHC Processes
MHC Process
Carbon
Conductive Ink
Conductive Polymerb
Electroless Copper
Graphite
Non-Formaldehyde
Electroless Copper
Organic-Palladium15
Tin-Palladium
Bath Type
Carbon Black
Cleaner
Conditioner
Microetch
Other (Anti-Tarnish)
Print Ink
Catalyst
Conductive Polymer
Microetch
Accelerator
Anti-Tarnish
Catalyst
Cleaner/Conditioner
Electroless Copper
Microetch
Predip
Cleaner/Conditioner
Fixer
Graphite
Microetch
Accelerator
Catalyst
Electroless Copper
Microetch
Conductor
Microetch
Postdip
Accelerator
Catalyst
Cleaner/Conditioner
Microetch
Other
Acid Dip
Hazardous Property"
Sensitizer
2(6)
Acute Health
Hazard
3(4)
1(2)
3(3)
2(2)
2(2)
1(5)
2(4)
2(10)
1(8)
5(25)
3(9)
3(4)
2(3)
3(4)
1(2)
2(2)
3(6)
3(4)
1(10)
3(9)
1(6)
2(5)
2(3)
Chronic Health
Hazard
3(4)
1(2)
3(3)
2(2)
2(4)
2(10)
1(8)
4(25)
1(9)
2(4)
2(4)
2(2)
2(6)
1(4)
3(9)
2(5)
Irreversible
Eye Damage
4(4)
2(2)
2(3)
2(2)
2(2),
2(5)
3(3)
2(3)
1(1)
1(5)
2(4)
6(10)
3(8)
13 (25)
4(9)
5(6)
1(1)
1(3)
2(4)
4(6)
3(4)
2(2)
1(1)
KD
9(10)
4(9)
2(6)
3(5)
3(3)
KD
* Table entries are made in the following format - # of products meeting OSHA definition for the given hazardous
property as reported in the product's MSDSs (Total # of products in the process bath). A blank entry means that
none of the products for the specific process bath meet the OSHA reporting criteria for the given property.
Example: For the palladium process cleaner/conditioner bath, 2 (6) means that two of the six products in the bath
were classified as sensitizers per OSHA criteria as reported by the products MSDSs.
b Hazardous properties based on German equivalent of MSDS, which may not have same reporting requirements of
U.S. MSDS.
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3.5 PROCESS SAFETY ASSESSMENT
Sensitizer - A sensitizer is defined by OSHA [29 CFR 1910.1200 Appendix A (mandatory)] as a
chemical that causes a substantial proportion of exposed people or animals to develop an allergic
reaction in normal tissue after repeated exposure to the chemical. Only two chemical products
were reported as sensitizers by MSDS data, both palladium MHC process chemicals.
Acute and Chronic Health Hazards - As defined by OSHA (29 CFR 1910.1200 Appendix A), a
chemical is considered a health hazard if there is statistically significant evidence based on at
least one study conducted in accordance with established scientific principles that acute or
chronic health effects may occur in exposed employees. Health hazards are classified using the
criteria below:
• Acute health hazards are those whose effects occur rapidly as a result of short-term
exposures, and are usually of short duration.
• Chronic health hazards are those whose effects occur as a result of long-term exposure,
and are of long duration.
Chemicals that are considered a health hazard include carcinogens, toxic or highly toxic agents,
reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, nuerotoxins,
agents which act on the hematopoietic system, and agents which damage the lungs, skin, eyes, or
mucous membranes.
A review of MSDS data found 51 chemical products reported as potentially posing acute
health hazards, and 33 chemical products potentially posing chronic health hazards. OSHA does
not require reporting of environmental hazards such as aquatic toxicity data, nor are toxicity data
on MSDSs as comprehensive as the toxicity data collected for the CTSA. OSHA health hazard
data are presented here for reference purposes only, and are not used in the risk characterization
component of the CTSA.
Carcinogen - As defined by OSHA (29 CFR 1910.1200 Appendix A), a chemical is considered to
be a carcinogen if: 1) it has been evaluated by the International Agency for Research on Cancer
(IARC), and found to be a carcinogen or potential carcinogen; 2) it is listed as a carcinogen or
potential carcinogen in the Annual Report on Carcinogens published by the National Toxicology
Program (NTP); or 3) it is regulated by OSHA as a carcinogen. Formaldehyde, which is used as
a reducing agent in the electroless copper process, is a suspected human carcinogen. A review of
MSDS data found that six chemical products were reported as potential carcinogens. All of the
products contain formaldehyde and are utilized in the electroless copper bath of the traditional
electroless copper process.
Dermal or Eye Irritant - An irritant is defined by OSHA [29 CFR 1910.1200 Appendix A
(mandatory)] as a chemical, which is not corrosive, but which causes a reversible inflammatory
effect on living tissue by chemical action at the site of contact. A chemical is considered a
dermal or eye irritant if it is so determined under the testing procedures detailed in 16 CFR
1500.41- 42. A review of MSDS data found that all but six of the 181 MHC chemical products
reviewed are reported as either dermal or eye irritants.
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3.5 PROCESS SAFETY ASSESSMENT
Irreversible Eye Damage - Chemical products that, upon coming in contact with eye tissue, can
cause irreversible damage to the eye are required by OSHA to be identified as such on the
product's MSDS. A review of MSDS data found that 91 chemical products are reported as
having the potential to cause irreversible eye damage.
3.5.4 Other Chemical Hazards
MHC chemical products that have the potential to form hazardous decomposition
products are presented below. In addition, chemical product incompatibilities with other
chemicals or materials are described, and other chemical hazard categories presented. The
following lists OSHA definitions for chemicals in these categories and summarizes the MSDS
data where appropriate.
Hazardous Decomposition - A chemical product, under specific conditions, may decompose to
form chemicals that are considered hazardous. With few exceptions, the MSDS data for the
chemical products in the MHC process indicate the possibility of decomposition to form a
potentially hazardous chemical. Each chemical product should be examined to determine its
decomposition products so that potentially dangerous reactions and exposures can be avoided.
The following are examples of hazardous decomposition of chemical products that are employed
in the MHC alternatives:
• When heated, a chemical product used to create an electroless copper bath can generate
toxic formaldehyde vapors.
• If allowed to heat to dryness, a graphite bath process chemical could result in gas releases
of ammonia, carbon monoxide, and carbon dioxide.
• Thermal decomposition under fire conditions of certain chemical bath constituents of a
palladium cleaner/conditioner bath can result in releases of toxic oxide gases of nitrogen
and carbon.
Incompatibilities - Chemical products are often incompatible with other chemicals or materials
with which they may come into contact. A review of MSDS data found that all of the MHC
processes have chemical products with incompatibilities that can pose a threat to worker safety if
the proper care is not taken to prevent such occurrences. Incompatibilities reported range from
specific chemicals or chemical products, such as acids or cyanides, to other materials, such as
rubber or textiles, like wood and leather. Chemical incompatibilities that are common to
products from all the MHC processes include acids, alkalis, oxidizers, metals, and reducing
agents. Incompatibilities were also found to exist between chemical products used on the same
process line. Individual chemical products for each process bath should be closely examined to
determine specific incompatibilities and care should be taken to avoid contact with incompatible
chemicals and chemical products, textiles, and storage containers.
The following are examples of chemical incompatibilities that exist for chemical products
that are employed in the MHC alternatives:
• An electroless copper bath contains chemical products that, when contacted with
hydrochloric acid which is present in other electroless copper process baths, will result in
reaction forming bis-chloromethyl ether, an OSHA-regulated carcinogen.
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3.5 PROCESS SAFETY ASSESSMENT
• Violent reactions can result when a chemical product of the conductive polymer catalyst
bath comes into contact with concentrated acids or reducing agents, both of which are
used in PWB manufacturing processes.
• A microetch bath of a graphite process contains chemicals that will react to form
hazardous gases when contacted with other chemical products containing cyanides,
sulfides, or carbides.
• Hazardous polymerization of a particular conductive ink product can occur when the
product is mixed with chemicals products containing amines, anhydrides, mercaptans, or
imidazoles.
Other Chemical Hazard Categories - OSHA requires the reporting of several other hazard
categories on the MSDSs for chemicals or chemical products that have not already been
discussed above. These additional categories include chemical products that are:
• Water-reactive (react with water to release a gas that presents a health hazard).
• Pyrophoric (will ignite spontaneously in air at temperatures below 130 °F).
• Stored as a compressed gas.
• Classified as an organic peroxide.
• Chemicals that have the potential for hazardous polymerization.
A review of MSDS data indicated that none of the chemical products are reported as
being water-reactive, pyrophoric, a compressed gas, an organic peroxide, or as having the
potential for hazardous polymerization.
3.5.5 Process Safety Concerns
Exposure to chemicals is just one of the safety issues that PWB manufacturers may have
to deal with during their daily activities. Preventing worker injuries should be a primary concern
for employers and employees alike. Work-related injuries may result from faulty equipment,
improper use of equipment, bypassing equipment safety features, failure to use personal
protective equipment, and physical stresses that may appear gradually as a result of repetitive
motions (i.e., ergonomic stresses). Any or all of these types of injuries may occur if proper
safeguards or practices are not in place and adhered to. An effective worker safety program
includes:
• An employee training program.
• Employee use of personal protective equipment.
• Proper chemical storage and handling.
• Safe equipment operating procedures.
The implementation of an effective worker safety program can have a substantial impact
on business, not only in terms of direct worker safety, but also in reduced operating costs as a
result of fewer days of absenteeism, reduced accidents and injuries, and lower insurance costs.
Maintaining a safe and efficient workplace requires that both employers and employees recognize
and understand the importance of worker safety and dedicate themselves to making it happen.
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Employee Training
A critical element of workplace safety is a well-educated workforce. To help achieve this
goal, the OSHA Hazard Communication Standard requires that all employees at PWB
manufacturing facilities (regardless of the size of the facility) be trained in the use of hazardous
chemicals to which they are exposed. A training program should be instituted for workers,
especially those operating the MHC process, who may come into contact with, or be exposed to,
potentially hazardous chemicals. Training may be conducted by either facility staff or outside
parties who are familiar with the PWB manufacturing process and the pertinent safety concerns.
The training should be held for each new employee, as well as periodic retraining sessions when
necessary (e.g., when a new MHC process is instituted), or on a regular schedule. The training
program should explain to the workers the types of chemicals with which they work and the
precautions to be used when handling or storing them; when and how personal protection
equipment should be worn; and how to operate and maintain equipment properly.
Storing and Using Chemicals Properly
Because the MHC process requires handling of a variety of chemicals, it is important that
workers know and follow the correct procedures for the use and storage of the chemicals. Much
of the use, disposal, and storage information about MHC process chemicals may be obtained
from the MSDSs provided by the manufacturer or supplier of each chemical or formulation. Safe
chemical storage and handling involves keeping chemicals in their proper place, protected from
adverse environmental conditions, as well as from other chemicals with which they may react.
Examples of supplier recommended storage procedures found on the MSDSs for MHC chemicals
are listed below:
• Store chemical containers in a cool, dry place away from direct sunlight and other sources
of heat.
• Chemical products should only be stored in their properly sealed original containers and
labeled with the generic name of the chemical contents.
• Incompatible chemical products should never be stored together.
• Store flammable liquids separately in a segregated area away from potential ignition
sources or in a flammable liquid storage cabinet.
Some products have special storage requirements and precautions listed on their MSDSs
(e.g., relieving the internal pressure of the container periodically). Each chemical product should
be stored in a manner consistent with the recommendation on the MSDS. In addition, chemical
storage facilities must be designed to meet any local, state, and federal requirements that may
apply.
Not only must chemicals be stored correctly, but they must also be handled and
transported in a manner which protects worker safety. Examples of chemical handling
recommendations from suppliers include:
• Wear appropriate protective equipment when handling chemicals.
• While transporting chemicals, do not use open containers.
• Use only spark-proof tools when handling flammable chemicals.
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3.5 PROCESS SAFETY ASSESSMENT
» Transfer chemicals using only approved manual or electrical pumps to prevent spills
created from lifting and pouring.
Proper chemical handling procedures should be a part of the training program given to
every worker. Workers should also be trained in chemical spill containment procedures and
emergency medical treatment procedures in case of chemical exposure to a worker.
Use of Personal Protective Equipment
OSHA has developed several personal protective equipment standards that are applicable
to the PWB manufacturing industry. These standards address general safety and certification
requirements (29 CFR Part 1910.132), the use of eye and face protection (Part 1910.133), head
protection (Part 1910.135), foot protection (Part 1910.136), and hand protection (Part 1910.138).
The standards for eye, face, and hand protection are particularly important for the workers
operating the MHC process where there is close contact with a variety of chemicals, of which
nearly all irritate or otherwise harm the skin and eyes. In order to prevent or minimize exposure
to such chemicals, workers should be trained in the proper use of personal safety equipment.
The recommended personal protective equipment for a worker handling chemicals is also
indicated on the MSDS. For the majority of MHC chemicals, the appropriate protective
equipment indicated by the MSDS includes:
Goggles to prevent the splashing of chemical into the eyes.
Chemical aprons or other impervious clothing to prevent splashing of chemicals on
clothing.
Gloves to prevent dermal exposure while operating the process.
Boots to protect against chemical spills.
Other items less widely suggested include chemically resistant coveralls and hats. In
addition to the personal protective equipment listed above, some MSDSs recommended that
other safety equipment be readily available. This equipment includes first aid kits, oxygen
supplies (SCBA), arid fire extinguishers.
Other personal safety considerations are the responsibility of the worker. Workers should
be discouraged from eating or keeping food near the MHC process. Because automated
processes contain moving parts, workers should also be prohibited from wearing jewelry or loose
clothing, such as ties, that may become caught in the machinery and cause injury to the worker or
the machinery itself: In particular, the wearing of rings or necklaces may lead to injury. Workers
with long hair that may also be caught in the machinery should be required to securely pull their
hair back or wear a hair net.
Use of Equipment Safeguards
In addition to the use of proper personal protection equipment for all workers, OSHA has
developed safety standards (29 CFR Part 1910.212) that apply to the actual equipment used in a
PWB MHC process. Among the safeguards recommended by OSHA that may be used for
conveyorized equipment are barrier guards, two-hand trip devices, and electrical safety devices.
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3.5 PROCESS SAFETY ASSESSMENT
Safeguards for the normal operation of conveyor equipment are included in the standards for
mechanical power-transmission apparatus (29 CFR Part 1910.219) and include belts, gears,
chains, sprockets, and shafts. PWB manufacturers should be familiar with the safety
requirements included in these standards and should contact their local OSHA office or state
technical assistance program for assistance in determining how to comply with them.
In addition to normal equipment operation standards, OSHA also has a lockout/tagout
standard (29 CFR Part 1910.147). This standard is designed to prevent the accidental start-up of
electric machinery during cleaning or maintenance operations that apply to the cleaning of
conveyorized equipment as well as other operations. OSHA has granted an exemption for minor
servicing of machinery provided the equipment has other appropriate safeguards, such as a
stop/safe/ready button which overrides all other controls and is under the exclusive control of the
worker performing the servicing. Such minor servicing of conveyorized equipment can include
clearing fluid heads, removing jammed panels, lubricating, removing rollers, minor cleaning,
adjusting operations, and adding chemicals. Rigid finger guards should also extend across the
rolls, above and below the area to be cleaned. Proper training of workers is required under the
standard whether lockout/tagout is employed or not. For further information on the applicability
of the OSHA lockout/tagout standard to MHC process operations, contact the local OSHA field
office.
Occupational Noise Exposure
OSHA has also developed standards (29 CFR Part 1910.95) that apply to occupational
noise exposure. These standards require protection against the effects of noise exposure when
the sound levels exceed certain levels specified in the standard. No data was collected on actual
noise levels from MHC process lines, but one PWB manufacturer suggested protective measures
may be needed to reduce noise levels from air knife ovens on carbon and graphite lines. This
manufacturer installed baffles on his system to reduce noise levels (Kerr, 1997).
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Chapter 4
Competitiveness
This chapter of the Cleaner Technologies Substitutes Assessment (CTSA) presents
information on basic issues traditionally important to the competitiveness of a printed wiring
board (PWB) manufacturer: the performance characteristics of the making holes conductive
(MHC) technologies relative to industry standards; the direct and indirect production costs
associated with the MHC technologies; the federal environmental regulations affecting chemicals
used in or waste streams generated by a technology; and the implications of an MHC technology
choice on global competitiveness. A CTSA weighs these traditional competitiveness issues
against issues business leaders now know are equally important: the health and environmental
impacts of alternatives products, processes, and technologies. Section 4.1 presents the results of
the Performance Demonstration Project. Section 4.2 presents a comparative cost analysis of the
MHC technologies. Section 4.3 lists the federal environmental regulations affecting chemicals in
the various technologies. Section 4.4 summarizes information pertaining to the international use
of the technologies, including reasons for adopting alternatives to electroless copper worldwide.
4.1 PERFORMANCE DEMONSTRATION RESULTS
4.1.1 Background
This section of the CTSA summarizes performance information collected during
performance demonstrations of MHC technologies. These demonstrations were conducted at 25
volunteer PWB facilities in the U.S. and Europe, between September and November, 1995.
Information from the performance demonstrations, taken in conjunction with risk, cost, and other
information in this document, provides a more complete assessment of alternative technologies
than has previously been available from one source.
In a joint and collaborative effort, Design for the Environment (DfE) project partners
organized and conducted the performance demonstrations. The demonstrations were open to all
suppliers of MHC technologies. Prior to the start of the demonstrations, DfE project partners
advertised the project and requested participation from all interested suppliers through trade
shows, conferences, trade journals, and direct telephone calls.
4.1.2 Performance Demonstration Methodology
The detailed performance demonstration methodology is attached in Appendix F. The
general plan for the demonstrations was to collect information about MHC technologies at
facilities where the technologies were already in use. The information collected through the
demonstrations was intended to provide a "snapshot" of the way the technology was performing
at that particular facility at that particular time. It is important to note that the methodology was
developed by consensus by a technical workgroup, which included suppliers, trade association
representatives, the U.S. Environmental Protection Agency (EPA), and many PWB
manufacturers.
4-1
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4.1 PERFORMANCE DEMONSTRATION RESULTS
Each supplier was asked to submit the names of up to two facilities where they wanted to
see the demonstrations of their technology conducted. This selection process encouraged the
suppliers to nominate the facilities where their technology was performing at its best. This, in
turn, provided for more consistent comparisons across technologies. The sites included 23
production facilities and two supplier testing facilities. While there were no pre-screening
requirements for the technologies, the demonstration facilities did have to meet the requirements
of the performance demonstration methodology.
For the purposes of the Performance Demonstration Project, the MHC process was
defined as everything from the desmear step through 0.1 mil of copper flash plating. In order to
minimize differences in performance due to processes outside this defined MHC function, the
panels used for testing were all manufactured and drilled at one facility. One hundred panels,
described below, were produced. After drilling, three panels were sealed in plastic bags with
desiccant and shipped to each test site to be processed through the site's MHC line. All bags
containing panels remained sealed until the day of processing.
An on-site observer from the DfE project team was present at each site from the point the
bags were opened until processing of the test panels was completed. Observers were present to
confirm that all processing was completed according to the methodology and to record data.
Each test site's process was completed within one day; MHC processing at all sites was
completed over a two month period.
When the MHC processing was completed, the panels were put into sealed bags with
desiccant and shipped to a single facility, where they remained until all the panels were collected.
At this facility, the panels were electroplated with 1.0 mil of copper followed by a tin-lead etch
resist, etched, stripped of tin-lead, solder mask coated, and finished with hot air solder leveling
(HASL). A detailed account of the steps taken in this process is included in Appendix F.
After HASL, the microsection coupons were routed out of the panels and sent to Robisan
Laboratory Inc. for mechanical testing. The Interconnect Stress Test (1ST) coupons were left in
panel format. The panels containing the coupons were passed twice through an IR reflow to
simulate assembly stress. A detailed protocol describing the IR reflow process is also included in
Appendix F. The panels with the 1ST coupons were then sent to Digital Equipment Corporation
of Canada (DEC Canada) for electrical prescreening and electrical testing.
Limitations of Performance Demonstration Methodology
This performance demonstration was designed to provide a snapshot of the performance
of different MHC technologies. Because the test sites were not chosen randomly, the sample
may not be representative of all PWB manufacturing facilities in the U.S. (although there is no
specific reason to believe that they are not representative). In addition, the number of test sites
for each type of technology ranged from one to ten. Due to the smaller number of test sites for
some technologies, results for these technologies could more easily be due to chance than the
results from technologies with more test sites. Statistical relevance cannot be determined.
4-2
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
4.1.3 Test Vehicle Design
All of the test panels were manufactured by H-R Industries, Inc. The test panel measured
24" x 18", laminated to 0.062", with eight layers. Test panels were produced from B and C stage
FR4 materials. Artwork, lamination specifications, and a list of the steps taken to manufacture
the panels are included in Appendix F.
Each test panel contained 54 test coupons: 271ST coupons (used for electrical testing)
and 27 microsection coupons. 1ST coupons measured 6.5" x 3/4" and contained 700
interconnecting vias on a seven row by 100 via 0.050" grid. This coupon contained two
independent circuits: the post circuit and the plated through-hole (PTH) circuit. The post circuit
contained 200 interconnects, and was used to measure post interconnect resistance degradation.
The PTH circuit contained 500 interconnects, and was used to measure PTH (barrel) interconnect
resistance degradation. 1ST coupons had either 0.013" or 0.018" holes (finished).
The microsection coupon measured 2" x 2" and contained 100 interconnected vias on a
10 row by 10 via 0.100" grid. It had internal pads at the second and seventh layer and a daisy
chain interconnect between the two surfaces of the coupon through the via. Microsection
coupons had either 0.013", 0.018", or 0.036" holes (finished).
This study was a snapshot based on products built with B and C stage FR4 materials and
this specific board construction. The data cannot necessarily be extrapolated to other board
materials or constructions.
4.1.4 Electrical and Microsection Testing Methodology
Electrical Testing Methodology
The 1ST coupons in panel format were electrically prescreened to determine defects on
arrival. The panels were then shipped to another facility for routing of the 1ST coupons, and
were shipped back to DEC Canada for completion of electrical testing.
Electrical testing was completed using the 1ST technology. 1ST is an accelerated stress
test method used for evaluating the failure modes of PWB interconnect. This method uses DC
current to create the required temperatures within the interconnect. There are three principal
types of information generated from the 1ST:
• Initial resistance variability.
• Cycles to failure (barrel integrity).
• Post separation/degradation (post interconnect).
The resistance value for the first internal circuit (PTH circuit) for each coupon was
determined. This gives an indication of the resistance variability (plating thickness) between
coupons and between panels. The initial resistance testing was also used to determine which
coupons had defects on arrival, or were unsuitable for further testing.
4-3
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4.1 PERFORMANCE DEMONSTRATION RESULTS
The cycles to failure indicate how much stress the individual coupons can withstand
before failing to function (measuring barrel integrity). 1ST coupons contained a second internal
circuit (post circuit) used to monitor the resistance degradation of the post interconnect.
The level of electrical degradation in conjunction with the number of cycles completed is
used to determine the presence and level of post separation. The relative performance of the
internal circuits indicates which of the two internal circuits, the post circuit or the PTH circuit,
has the dominant failure mechanism. The draft Institute for Interconnecting and Packaging
Electronic Circuits (IPC) 1ST test method is included in Appendix F.
Mechanical Testing Methodology
The coupons for mechanical testing were sent to Robisan Laboratory Inc. for testing.
Mechanical testing consisted of evaluations of metallurgical microsections of plated through-
holes in the "as produced" condition and after thermal stress. One test coupon of each hole size
from each panel was sectioned. The direction the coupons were microsectioned was determined
by visually examining the coupons to determine the direction of best registration to produce the
most inner layer circuitry connections in the microsections.
Microsections were stressed per IPC-TM-650, method 2.6.8, included in Appendix F.
The plated through-holes were evaluated for compliance to the requirements found in IPC-RB-
276. Microsections were examined after final polish, prior to metallurgical microetch, and after
microetch.
The original test plan called for selection of 1ST and microsectioning coupons from
similar locations on each panel. Following prescreening, the coupon selection criteria was
amended to be based on coupons with the best registration. This resulted in some coupons being
selected from areas with known thicker copper (see Results of Electrical Prescreening below).
Four 0.013" 1ST coupons were selected from each of the three test panels from each test
site. Test Site #3 and Test Site #4 had only two available test panels, therefore six coupons were
selected from each panel. Three coupons from within six inches of the 1ST coupons selected
were microsectioned from the same panels. In some cases, the desired microsection coupons
exhibited misregistration, so next-best locations were used. In all cases, coupons selected were
located as close to the center of the panel as possible.
Limitations of Testing Methodology
Fine line evaluations hi microsections have always been a point of contention within the
industry. Current microsection specifications state that any indication of separation between the
hole wall plating and the inner layer is sufficient grounds to reject the product. An indication of
post separation would be a line on the microsection thicker than what normally appears with
electroless copper technology (normal average: 0.02 - 0.04 mils). Separation may also be
determined by a variation in the thickness of the line across the inner layer connection, especially
on electroless deposits that are very thin. The rationale for these rejection criteria is that product
with post separation degrades with time and temperature cycling.
4-4
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
With traditional electroless copper products where post separation is present, it can
usually be determined where the separation occurs: between the electroless and foil, within the
electroless, or between the electroless and the electrolytic plating. This determination often helps
in troubleshooting the plating process. In this study, some of the alternative technologies resulted
in no line at all after microetch on the microsections. This posed a problem in interpretation of
results. If traditional criteria are used to determine inner layer separation (i.e., the line of
demarcation is thicker on some inner connects than others, and the electroless can be seen as
continuous between the inner layer and plated copper), then accurate evaluations of product with
no lines would not be possible. In this study, the criteria used on "no line" products was that if
the sections exhibited any line of demarcation after microetch, the product is considered to have
inner layer separation.
This issue is significant to the PWB industry because there remains a question about the
relationship between the appearance of a line on the microsection to the performance of a board.
Traditionally (with electroless copper products), the appearance of a line thicker than normal
electroless line is considered to be post separation, and the board is scrapped. However, there are
no criteria for how to evaluate "no line" products. In addition, there are no official means of
determining when "a little separation" is significant to the performance of the board.
1ST is not a subjective test and is not dependent upon the presence or absence of a line in
a microsection after microetch. The test provides a relative number of 1ST cycles necessary to
cause a significant rise hi resistance in the post interconnect. This number of cycles may be used
to predict interconnect performance. Tests such as this, when correlated with microsections, can
be useful in determining how to interpret "no line" product characteristics. In addition, 1ST may
be able to determine levels of post separation.
The figures included in Appendix F in the IPC 1ST test method show various failure
mechanisms exhibited by different test sites and panels. Future industry studies must determine
the relevance of these curves to performance, based on number of cycles needed to raise the
resistance as well as the amount of change in resistance. Definitions for "marginal" and "gross"
separations may be tied to life-cycle testing and subsequently related to class of boards produced.
4.1.5 Results
Product performance for this study was divided into two functions: PTH cycles to failure
and the integrity of the bond between the internal lands (post) and the PTH. The PTH cycles to
failure observed in this study is a function of both electrolytic plating and the MHC process. The
results indicate that each MHC technology has the capability to achieve comparable (or superior)
levels of performance to electroless copper.
Results are presented in this section for all three stages of testing conducted:
1. Electrical prescreening, which included tests for:
• Defects on arrival based on resistance measurements.
• Print and etch variability based on resistance distribution of the post circuit.
• Plating variability based on resistance distribution of the PTH circuit.
_ :
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
2. Microsection evaluation, which examined:
• Plating voids.
• Drill smear.
• Resin recession.
• Post separation.
• Average copper plating thickness.
3. Interconnect stress testing, which measured:
• Mean cycles to failure of the PTH interconnect.
• Post degradation/separation within the post interconnect.
Results of Electrical Prescreening
Seventy-four of 75 test panels from 25 test facilities were returned. One of the 74 proved
to be untestable due to missing inner layers. The results of the prescreening will be reported in
the following categories: defects on arrival (unacceptable for testing), print and etch variability,
and plating (thickness) variability.
Defects on Arrival. A total of 1,971 coupons from the 73 panels each received two
resistance measurements using a four wire resistance meter. The total number of holes tested
was 1.4 million. As shown in Table 4.1, one percent (19) of coupons were found to be defective,
and were considered unacceptable for 1ST testing because of opens and shorts.
Test Site #
1
3
11
12
14
16
20
MHC Technology
Electroless
Electroless
Graphite
Graphite
Palladium
Palladium
Palladium
Opens
1
2
1
2
2
Shorts
4
2
5
Following an inspection of the defective coupons, the opens were found to be caused by
voiding, usually within a single via. Shorts were caused by misregistration. The type of MHC
technology did not contribute to the shorts.
Print and Etch Variability. The resistance distribution for the po'st circuit was
determined. Throughout manufacturing, the layers/panels were processed in the same
orientation, which provided an opportunity to measure resistance distributions for each
coupon/panel. The distribution proved very consistent. This result confirms that inner layer
printing and etching did not contribute to overall resistance variability. Table 4.2 depicts the
mean post circuit resistance for five 0.013" coupon locations (in milliohrns) for all 73 panels.
~
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.2 Mean Post Circuit Resistance Measurements, in Milliohms
(coupon locations on panel)
409
415
399
405
411
Plating Variability. The resistance distribution for the PTH circuit was determined as an
indicator of variability. The results indicated that overall resistance variability was due to plating
thickness variability rather than print and etch variability. Table 4.3 depicts the mean PTH
circuit resistance for five 0.013" coupon locations (hi milliohms) for all 73 panels.
Table 4.3 Mean PTH Circuit Resistance Measurements, in Milliohms
(coupon locations on panel)
254
241
244
239
225
The PTH interconnect resistance distribution showed the electrolytic copper plating
increased in thickness from the top to the bottom of each panel. Copper thickness variability was
calculated to be 0.0003" thicker at the bottom compared to the top of each panel. Resistance
variability, based on 54 measurements per panel, was also found from right to left on the panels.
Inconsistent drill registration or outer layer etching was thought to be the most probable cause of
this variability. When a number of holes break out of their pads, it increases the internal copper
area, causing the resistance to decrease. This reduction in resistance creates the impression the
coupons have thicker copper.
\
Table 4.4 lists the means and standard deviation of all PTH resistance measurements and
the levels of correlation among panels observed at each site. As seen in Table 4.4, copper plating
distribution at each site was good. Plating cells and rack/panel locations did not create large
variability that could affect the results of each test site. Because resistance (plating thickness)
distribution was also consistent among test sites, relative comparisons among the different MHC
technology sites can be made. Only one site, Test Site #12, was calculated to have poor
correlation between all three panels.
It was determined during correlation that the variations in hole wall plating thickness
indicated by electrical prescreening were due to variations in the flash plate provided by each test
site and not due to variations in electrolytic plating.
4-7
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.4 Prescreenins Results - 0.013" Vias for All Test Sites8
Site#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Mean Res.
239
252
238
232
236
266
253
230
243
248
226
240
231
247
243
239
240
245
226
229
250
256
253
239
224
StaBev,
14.5
17.6
12.5
11.2
12.1
15.7
14.2
11.6
10.6
13.0
19.0
23.0
16.0
26.8
11.1
15.9
12.8
9.7
10.2
10.2
13.3
8.8
12.5
12.0
13.9
Fnl#l
234
269
227
224
239
255
240
221
247
256
216
254
243
256
236
232
247
245
223
219
258
256
257
241
210
Pal #2
245
251
248
239
241
275
259
228
247
242
221
235
235
227
244
243
243
249
232
238
243
261
257
232
232
Pfli#3
237
234
N/A
N/A
229
266
259
241
235
247
241
231
215
258
248
241
231
240
223
229
249
250
244
246
231
Corr.
All
2
All
All
2
2
All
2
2
All
2
None
2
All
2
All
All
All
2
2
2
All
All
All
All
Site #6, an electroless copper site, may not have performed to its true capability on the day of the test. Due to a
malfunction in the line, the electroless copper bath was controlled by manual lab analysis instead of by the usual
single-channel controller.
Mean Res. - Mean resistance of all coupons on the three panels.
Std Dev. - Standard deviation for all coupons per test site.
Pnl# - Mean resistance for listed panel.
Corr. - Correlation Coefficient >.7 between each panel.
Sample size for each test site: 12.
Remaining test results will be reported for each type of MHC technology, represented by
the following test sites shown in Table 4.5.
4-8
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.5 Correlation of MHC Technologies with Test Site Numbers
Test Site #
1-7
8-9
10-12
13-22
23-24
25
MHC Technology
Electroless Copper
Carbon
Graphite
Palladium
Non-Formaldehyde Electroless Copper
Conductive Polymer
§ of Test Sites
7
2
3
10
2
1
Results of Microsection Evaluation
The only defects reported in this study were voids in hole wall copper, drill smear, resin
recession, and inner layer separation. Average hole wall thickness was also reported for each
panel. Defects present but not included as part of this report are registration, inner layer foil
cracks, and cracks in flash plating at the knees of the holes. These defects were not included
because they were not believed to be a function of the MHC technology. The inner layer foil
cracks appear to be the result of the drilling operation and not a result of z-axis expansion or
defective foil. None of the cracks in the flash plating extended into the electrolytic plate in the
coupons as received or after thermal stress. Therefore, the integrity of the hole wall was not
affected by these small cracks.
Plating Voids. There were no plating voids noted on any of the coupons evaluated. The
electrolytic copper plating was continuous and very even with no indication of any voids.
Drill Smear. The panels exhibited significant amounts of nailheading. Since
nailheading was present on all panels, it was determined that all test sites had received similar
panels to process and therefore, comparisons were possible. The main concern with the presence
of nailheading was that the amount of drill smear might be excessive compared to each test site's
"normal" product. Drill smear negatively impacts inner layer connections to the plated hole wall
if not removed.
Resin Recession. No samples failed current specification requirements for resin
recession. There was, however, a significant difference in the amount of resin recession among
test sites.
Inner Layer Separation. Different chemistries had different appearances after
metallurgical microetch. Electroless copper microsections traditionally have a definite line of
demarcation between foil copper and electrolytic copper after metallurgical microetch. This line
also appeared in electroless copper samples in this study. The line is the width of the electroless
deposit, and is very important in making a determination as to whether inner layers are separated
from the plated hole wall. Many of the products tested in this study had no line of demarcation
or lines which had little, if any, measurable width. For those MHC technologies that should not
have a line after microetch, the determination as to whether inner layer separation was present on
the samples was based on the presence of a line.
4-9
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4.1 PERFORMANCE DEMONSTRATION RESULTS
Over half of the test sites supplied product which did not exhibit inner layer separations
on as received or thermal stressed microsections. Some of the product exhibited inner layer
separation in the as received samples which further degraded after thermal stress. Other test sites
had product that showed very good interconnect as received and became separated as a result of
thermal stress.
The separations ranged from complete, very wide separations to very fine lines which did
not extend across the complete inner layer connection. No attempt was made to track these
degrees of separation because current specification requirements dictate that any separation is
grounds for rejection of the product.
Table 4.6 gives the percentage of panels from a test site that did or did not exhibit a
defect. The data are not presented by hole size because only Test Site #11 had defects on only
one size of hole. In all other test sites exhibiting defects, the defects were noted on all sizes of
holes.
Table 4.6 Proportion of Panels Exhibiting Defects
Test
Site#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Percentage of Panels
Exhibiting Defect
Drill Smr
0
66
0
100
0
0
0
0
0
0
0
0
0
0
0
0
33
0
0
0
0
0
0
0
0
Res Rec
33
66
0
0
0
0
100
0
0
0
33
0
33
0
0
0
33
33
100
0
0
66
0
0
0
Post Sep
0
100
0
0
0
100
0
0
0
0
66
100
0
0
33
100
33
66
0
100
100
0
100
0
0
Percentage of Panels Exhibiting
Defect per Technology
(average of all test sites)
Drill Smr
21
0
0
3.3
0
0
Res Rec
31.6
0
11
26.5
0
0
Post Sep
31.6
0
55.6
43.3
50
0
MHC Technology
Electroless Copper
Carbon
Graphite
Palladium
Non-Formaldehyde
Electroless Copper
Conductive Polymer
4-10
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.7 depicts the average measured copper plating thickness for all panels.
Table 4.7 Microsection Copper Plating Thickness (in mils)
Test Site
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Panel # 1
1.4
0.95
1.3
1.3
1.2
1.1
1.5
1.3
1.2
1.0
1.5
1.3
1.2
1.2
1.1
1.1
1.2
1.1
1.5
1.6
1.1
1.2
1.4
1.3
1.4
Panel #2
1.1
1.1
1.1
1.2
1.3
1.1
1.1
1.3
1.4
1.1
1.5
1.3
1.3
1.1
1.1
1.2
1.3
N/A
1.3
1.4
1.2
1.1
1.1
1.2
1.7
Panel #3
1.2
1.3
N/A
N/A
1.3
1.1
1.1
1.2
1.3
1.3
1.1
1.3
1.3
1.2
1.2
1.3
1.4
1.5
1.3
1.3
1.2
1.1
1.2
1.2
1.4
Average Cu
1.24
1.11
1.2
1.25
1.24
1.1
1.2
1.3
1.3
1.14
1.4
1.3
1.3
1.2
1.13
1.2
1.3
1.3
1.4
1.4
1.14
1.13
1.24
1.23
1.5
Results of Interconnect Stress Testing
Test results will be reported in various formats. Both tables and graphs will be used to
describe 1ST cycles to failure for the PTH interconnect and post degradation/separation within
the post interconnect. 1ST was completed on a total of 12 coupons from each test site.
Mean Cycles to Failure Testing Results. The mean cycles to failure for the PTH
interconnect are established at the point when the coupon exceeds a ten percent increase in the
initial elevated resistance. Mean 1ST cycles to failure and standard deviation by test site are
shown in Table 4.8. Table 4.9 shows the mean 1ST cycles to failure and standard deviations by
MHC technology.
4-11
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.8 Mean 1ST Cycles to Failure, by Test Site
Test Site # & MHC Technology Type
1 Electroless Copper
2 Electroless Copper
3 Electroless Copper
4 Electroless Copper
5 Electroless Copper
6 Electroless Copper
7 Electroless Copper
8 Carbon
9 Carbon
10 Graphite
11 Graphite
12 Graphite
13 Palladium
14 Palladium
15 Palladium
16 Palladium
17 Palladium
18 Palladium
19 Palladium
20 Palladium
21 Palladium
22 Palladium
23 Non-Formaldehyde Electroless Copper
24 Non-Formaldehyde Electroless Copper
25 Conductive Polymer
1ST Cycles to J?ail
346
338
323
384
314
246
334
344
362
317
416
313
439
284
337
171
370
224
467
443
267
232
214
261
289
Standard Deviation
91.5
77.8
104.8
70
50
107
93.4
62.5
80.3
80
73.4
63
55.2
62.8
75.3
145.7
122.9
59.7
38.4
52.5
40.5
86.6
133.3
41.6
63.1
Sample size = 12 coupons from each site.
Table 4.9 Mean 1ST Cycles to Failure, by MHC Technology
MHCTechpology
Electroless Copper
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Palladium
1ST Cycles to Fail
327
354
289
349
238
332
Standard Deviation
92.5
71
63.1
85.3
99.5
126
High standard deviations indicate that high levels of performance variability exist within
and among test sites.
4-12
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figures 4.1 through 4.6 identify the 1ST cycles to failure for each panel and test site for
each MHC technology. The two reference lines on each graph identify the mean cycles to failure
(solid line) for all 300 coupons tested (324 cycles) and the mean resistance (dotted line) for all
coupons measured (241 milliohms). When considering the overall performance of each panel, it
is useful to compare the mean resistance of the coupons to the dotted reference line. As
mentioned before, each test site was instructed to flash plate 0.0001" of electrolytic copper into
the holes. If the sites exceeded this thickness, the total copper thickness would be thicker,
lowering the resistance and increasing the performance of the panels. Therefore, panels with
lower resistance should be expected to perform better, and vice versa. Although each site was
requested to plate 0.0001" of electrolytic copper, the actual range was between 0.00005" and
0.0005".
Figure 4.1 Electroless Copper - 1ST Cycles to Fail vs. Resistance
Ul
a:
< o
UI
HUJ
450
400 -
350-
200-
150
100
50
0
• -t-
• H h
.L
1 1 [
J-t
_L , i.H.l.i
• 1ST CYCLES
HRESISTANCl
n
- •!"• 1 1 f«if
i-»-'-1 1
1 1
J-jM.
TEST SITES
All electroless copper test sites had at least one panel that met or exceeded the mean
performance. As shown in Figure 4.1, for the panels that did not achieve the mean performance,
it can be seen that the mean resistance column was above the reference line (thinner copper).
The exception was Test Site #6, which exhibited a high degree of post separation (see post
separation results section below for an explanation of results). As noted previously, Test Site #6
may not have performed to its true capability on the day of the test. Due to a malfunction in the
line, the electroless copper bath was controlled by manual lab analysis instead of by the usual
single-channel controller.
4-13
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figure 4.2 Carbon - 1ST Cycles to Fail vs. Resistance
500
450
400
350
O < 300 -
rr co
UJ W 250
II Ul
O Di 200
UJ
K
I «"
2i
<2 5
z +
<
UJ
150
100
50
0
• 1ST CYCLES
D RESISTANCE
TEST SITES
As shown in Figure 4.2, both carbon test sites had at least two panels that met or
exceeded the mean performance.
Figure 4.3 Graphite - 1ST Cycles to Fail vs. Resistance
450 -
+
Ul 400 •
o:
_1 uj 350 •
MEAN 1ST CYCLES TO F;
MEAN RESISTAN
-» -» N M U
Ot O Ol O Oi Q
3 O O O O O O
• 1ST CYCLES
D RESISTANCE
10 11 12
TEST SITES
All three graphite test sites had at least one panel that met or exceeded mean
performance, as shown in Figure 4.3.
4-14
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figure 4.4 Palladium - 1ST Cycles to Fail vs. Resistance
100
2 B
•t 32D__
Ifl
IST CYCLES
RESISTANCE
16 17 1B
TEST SITES
As shown in Figure 4.4, most palladium test sites had at least one panel that met or
exceeded the mean performance. Three test sites did not. Those test sites that did not achieve
the mean performance exhibited either high resistance or post separation.
Figure 4.5 Non-Formaldehyde Electroless Copper - 1ST Cycles to Fail vs. Resistance
23
TEST SITES
Neither non-formaldehyde electroless copper test site met or exceeded mean
performance, as shown hi Figure 4.5. Test Site #23 exhibited a high degree of post separation
(see post separation results section below for an explanation of results).
4-15
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figure 4.6 Conductive Polymer - 1ST Cycles to Fail vs. Resistance
500
• 1ST CYCLES
n RESISTANCE
As shown in Figure 4.6, the single conductive polymer test site had one panel that met or
exceeded the mean performance.
Post Separation Testing Results
1ST determines post interconnect performance (post separation) simultaneously with the
PTH cycles to failure performance. The failure criteria for post separation has not been
established. Further work is in progress with the IPC to create an accept/reject criteria. For this
study, the 1ST rejection criteria is based on a 15 milliohm resistance increase derived from the
mean resistance degradation measurement for all 300 coupons tested.
A reliable post interconnect should measure minimal resistance degradation throughout
the entire 1ST. Low degrees of degradation (<15 milliohms) are common and relate to the fatigue
of the internal copper foils. Resistance increases greater than 50 milliohms were reported as 50
milliohms. This was done in order to avoid skewing results.
The mean resistance degradation of the post interconnect is determined at the time the
PTH failed. The readings (in milliohms) for the post interconnect and the standard deviations for
each test site (sample size = 12 coupons from each site) and for each MHC technology are shown
hi Tables 4.10 and 4.11, respectively.
4-16
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.10 Mean Resistance Degradation of Post Interconnect, by Test Site
(in milliohms)
"Test Site # and MHC Technology Type
1 Electroless Copper
2 Electroless Copper
3 Electroless Copper
4 Electroless Copper
5 Electroless Copper
6 Electroless Copper
7 Electroless Copper
8 Carbon
9 Carbon
10 Graphite
11 Graphite
12 Graphite
13 Palladium
14 Palladium
15 Palladium
16 Palladium
17 Palladium
18 Palladium
19 Palladium
20 Palladium
21 Palladium
22 Palladium
23 Non-Formaldehyde Electroless Copper
24 Non-Formaldehyde Electroless Copper
25 Conductive Polymer
Post Degradation
13.1
17.2
6.6
6.7
3.8
34.8
4.1
2.8
2
5.2
8
16
9.5
2.8
7.9
32.2
0.8
7.6
4.7
13.7
40.5
4.5
47.9
4.2
2.8
Standard Deviation
3.5
12.9
3.7
2.7
2.4
13.1
4.6
2.9
2.5
3.9
8.1
15
4.7
2.6
7.4
18.1
1.8
6.4
3.3
5.6
11.3
2.6
7.2
1.9
1.8
Table 4.11 Mean Resistance Degradation of Post Interconnect, by MHC Technology
MHC Technology Type
Electroless Copper
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Palladium
Post Degradation
12.3
2.4
2.75
9.7
26
12.4
Standard Deviation
12.6
2.7
1.8
10.8
22.9
14.3
High standard deviations indicate that high levels of variability exist within and among
test sites and within an MHC technology.
4-17
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figures 4.7 through 4.12 identify the mean (average of four coupons per panel) 1ST post
resistance degradation results. The reference line on each graph identifies the mean resistance
degradation measurement for all 300 coupons tested (15 milliohms). If the mean resistance
degradation column is above the reference line, the panel had coupons that exhibited post
separation. The post resistance change was the value recorded at the point where the PTH
(barrel) failed.
Figure 4.7 Electroless Copper - Post Resistance Degradation
UJ
CD
z
o
111
o f>
Z 5
II
CO -I
UI ^
n: =
\-
tn
o
a.
z
<
HI
E
50 ,
45 •
40 •
35 .
30 •
25 •
20 -
15
10
5
0
ll
I
III ll ll.
,l
TEST SITES
As shown in Figure 4.7, two of the seven electroless copper test sites had at least one
panel that exhibited post separation. All three panels from Test Site #6 clearly exhibited gross
post separation. Both test methods for post separation failed all panels from Test Site #6. As
noted previously, Test Site #6 may not have performed to its true capability on the day of the test.
Due to a malfunction hi the line, the electroless copper bath was controlled by manual lab
analysis instead of by the usual single-channel controller.
4-18
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
ui
o
o
UI
o co
CO
o
a.
Figure 4.8 Carbon - Post Resistance Degradation
50
45
40
35 -
30
25
20
15
10
TEST SITES
No post separation was detected on any carbon panels, as shown in Figure 4.8.
Figure 4.9 Graphite - Post Resistance Degradation
UI
O
O
UI
o co
z S
al
co Zi
UI =
o: =
co
CO
2
I
11
TEST SITES
As shown in Figure 4.9, two of the three graphite test sites had at least one panel that
exhibited post separation.
4-19
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
so
45 •
Cj CO 40 -
Z 5
< I 35
2 § 30
V) _l
g 5 25
CO ~ 20
< I 1°
0
Figure 4.10 Palladium - Post Resistance Degradation
III 1.. ll.
1
13 14 15 16 17 18 19 20
TEST SITES
ill
21 22
As shown in Figure 4.10, four of the ten palladium test sites had at least one panel that
exhibited post separation. Test Site #16 and Test Site #21 clearly exhibited gross post
separation.
Figure 4.11 Non-Formaldehyde Electroless Copper - Post Resistance Degradation
TEST SITES
As shown hi Figure 4.11, all three panels for non-formaldehyde electroless copper Test
Site #23 clearly exhibited gross post separation.
4-20
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Figure 4.12 Conductive Polymer - Post Resistance Degradation
4.12.
UJ
o
z
I
o
UJ
o w
< I
so
45
35 •
30
25 -
= 20
10 .
5
0
25
TEST SITE
No post separation was detected on any conductive polymer panels, as shown in Figure
4.1.6 Comparison of Microsection and 1ST Test Results
Microsection and 1ST were run independently, and test results were not shared until both
sets of data were completed and delivered to EPA. To illustrate the consistency of the test
results, Table 4.12 identifies both test methods and their results for post separation detection.
"Y" or "N" (yes or no) denote whether post separation was detected on any coupon or
panel from each test site. The "panels affected" column refers to how many of the panels within
each test site exhibited post separation. Test Site #17 was the only site with post separation
found in the microsection but not on 1ST.
Post separation results indicated percentages of post separation that were unexpected by
many members of the industry. It was apparent that all MHC technologies, including electroless
copper, are susceptible to this type of failure. The results of this study further suggest that post
separation may occur in different degrees. The level of post separation may play a role in
determining product performance; however, the determination of levels of post separation
remains to be discussed and Confirmed by the PWB industry.
4-21
-------
4.1 PERFORMANCE DEMONSTRATION RESULTS
Table 4.12 IST/Microsection Data Correlation
Test Site #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Mlcrosection
N
Y
N
N
N
Y
N
N
N
N
Y
Y
N
N
Y
Y
Y
Y
N
Y
Y
N
Y
N
N
Panels Affected
0
3
0
0
0
3
0
0
0
0
2
3
0
0
1
3
1
2
0
3
3
0
3
0
0
1ST
N .
Y
N .
N
N
Y
N
N
N
N
Y
Y
N .
N
Y
Y
N
Y
N
Y
Y
N
Y
N
N
Panels Affected
0
3
0
0
0
3
0
0
0
0
1
2
0
0
1
3
0
2
0
2
3
0
3
0
0
4-22
-------
4.2 COST ANALYSIS
4.2 COST ANALYSIS
Operating an efficient and cost-effective manufacturing process with strict control of
material and production costs is the goal of every successful company. Fueled by consumer
demand for smaller and lighter electronics, rapid and continuous advances in circuit technology
make this goal a necessity for PWB manufacturers attempting to compete in today's global
marketplace. The higher aspect-ratio holes and tighter circuit patterns on current PWBs are
forcing manufacturers to continually evaluate and eventually replace aging manufacturing
processes that are unable to keep up with the ever-increasing technology threshold. When
coupled with the typically slim profit margins of PWB manufacturers, these process changes
represent a major capital investment to a company and emphasize the importance of selecting an
efficient, cost-effective process that will allow the company to remain competitive. As a result,
manufacturers are seeking comprehensive and more detailed cost data before investing in
alternative processes.
This section presents a comparative cost analysis of the MHC technologies. Costs were
developed for each technology and equipment configuration (vertical, immersion-type
equipment, or horizontal, conveyorized equipment) for which data were available from the IPC
Workplace Practices Questionnaire and Performance Demonstration. Table 4.13 presents the
processes (alternatives and equipment configurations) evaluated.
Table 4.13 MHC Processes Evaluated in the Cost Analysis
MHC Alternative
Electroless Copper
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
Non-Conveyorized
•
•
•
•
Conveyorized ;
•
•
•
•
•
•
Costs were analyzed using a cost model developed by the University of Tennessee
Department of Industrial Engineering. The model employs generic process steps and functional
groups (see Section 2.1, Chemistry and Process Description of MHC Technologies) and typical
bath sequences (see Section 3.1, Source Release Assessment) for each process alternative.
Figure 4.13 presents the generic process steps and typical bath sequences. To develop
comparative costs on a $/surface square foot (ssf) basis, the cost model was formulated to
calculate the cost of performing the MHC function on a job consisting of 350,000 ssf. This is the
average annual throughput for facilities in the IPC Workplace Practices Questionnaire database.
The cost for each process is compared to a generic non-conveyorized electroless copper process,
defined here as the baseline process.
4-23
-------
4.2 COST ANALYSIS
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1
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&
13
cn
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PH
1
o
4-24
-------
4.2 COST ANALYSIS
The overall objective of this analysis was to determine the comparative costs of the MHC
technologies using a cost model that adheres to fundamental principles of cost analysis. Other
objectives were to make the analysis flexible and to consider environmental costs. The cost
model was designed to estimate the comparative costs of fully operational MHC process lines. It
does not estimate start-up costs for a facility switching to an alternative MHC technology or the
cost of other process changes that may be required to implement a new MHC technology.
Section 4.2.1 gives an overview of the cost methodology. Section 4.2.2 presents simulation
model results. Section 4.2.3 describes details of the cost methodology and presents sample cost
calculations. Section 4.2.4 contains analysis results, while Section 4.2.5 presents a sensitivity
analysis of the results. Section 4.2.6 presents conclusions.
4.2.1 Overview of the Cost Methodology
The costs of the MHC technologies were developed by identifying the steps in each
process, breaking each step down into its cost components, and determining the cost of each
component. Component costs were determined utilizing traditional costing mechanisms,
computer simulation, and ABC. Computer simulation was used to replicate each of the MHC
processes to determine the time required to complete the specified job and other job-specific
metrics. ABC is a cost accounting method that allocates indirect or overhead costs to the
products or processes that actually incur those costs. Activity-based costs are determined by
developing bills of activities (BOAs) for tasks essential to the process. A BOA is a listing of the
component activities involved in the performance of a certain task, together with the number of
times each component activity is performed. The BOA determines the cost of a task by
considering the sequence of actions and the resources utilized while performing that task.
Framework for the Cost Formulation
Figure 4.14 presents the hybrid cost formulation framework used in this analysis. The
first step in the framework was to develop or define the alternatives to be evaluated. The generic
process descriptions, chemical baths, typical bath sequences, and equipment configurations were
defined in Table 4.13 and Figure 4.13. This information was used to identify critical variables
and cost categories that needed to be accounted for in the cost analysis. Cost categories were
analyzed to identify the data required to calculate the costs (i.e., unit costs, utilization or
consumption rates, criteria for performing an activity, such as chemical bath replacement, the
number of times an activity is performed, etc.). For each process, a computer simulation was
then developed using ARENA® computer simulation software and information derived from the
cost components. The simulations were designed to model a MHC manufacturing job consisting
of 350,000 ssf.
4-25
-------
4.2 COST ANALYSIS
Figure 4.14 Hybrid Cost Formulation Framework
MHC
Alternatives
Development of
Cost Categories
Development of
Simulation Model
Traditional Costs
Components
Activity-Based Cost
Components
T
Cost
Analysis
±
Sensitivity
Analysis
Simulation modeling provides a number of advantages to the cost analysis, including the
following:
• Simulation modeling can replicate a production run on the computer screen, allowing an
analyst to observe a process when the actual process does not exist. In this case, the
generic MHC technologies, as they are defined in Figure 4.13, may not exist within any
one facility.
• Simulation allows for process-based modifications and variations, resulting in inherent
flexibility within the system. Simulation models can be designed to vary the sequence of
operations, add or delete operations, or change process times associated with operations,
materials flows, and other variables.
• Data gathered from PWB manufacturers, chemical suppliers, and the Performance
Demonstration have some data gaps and inconsistencies. However, these data must be
aggregated to develop comparative costs of the generic MHC alternatives. Thus, data
collected from one or more facilities may not fully represent a generic MHC alternative or
group of alternatives. Process simulation based on fundamental assumptions and data
helps clear up data inconsistencies and fill data gaps.
• Simulation enables one to study the sensitivity of critical performance measures to
changes in underlying input variables. Constant input variables may be modified in the
sensitivity analysis to determine the uncertainty (in terms of probability distributions)
associated with these input variables.
Direct results of the simulation model and results derived from simulation outputs include
the folio whig:
4-26
-------
4.2 COST ANALYSIS
• The amount of time the MHC line operates to produce the job.
• The number of times an activity is performed during the course of the job.
• Consumption rates (e.g., water, energy, and chemical consumption).
• Production rates (e.g., wastewater generation).
Simulation results were combined with traditional cost components to adjust these costs
for the specified job. An example of this is the determination of equipment cost. Simulation
results were used to calculate a utilization ratio (UR), defined as the amount of time in days
required to produce 350,000 ssf divided by one operating year (defined as 250 days). Annualized
equipment costs were determined utilizing industry sources for equipment price and depreciation
guidelines from the Internal Revenue Service. These costs were multiplied by the UR to
determine the equipment costs for the job being evaluated.
Activity-based costs were determined by combining simulation results for the frequency
of activities with the cost of an activity developed on a BOA. For example, the activity costs of
replacing a particular bath were determined by developing a BOA, developing costs for each
activity on the BOA, and multiplying these costs by the number of bath replacements required to
complete a job of 350,000 ssf. In this manner, the overall analysis combines traditional costs
with simulation outputs and activity-based costs. The effects of critical variables on the overall
costs were then evaluated using sensitivity analysis.
Cost Categories
Table 4.14 summarizes the cost components considered in this analysis, gives a brief
description of each cost component and key assumptions, and lists the primary sources of data for
determining the costs. Section 4.2.3 gives a more detailed accounting of the cost components,
including sample cost calculations for each component.
In addition to traditional costs, such as capital, production, and maintenance costs, the
cost formulation identifies and captures some environmental costs associated with the
alternatives. In this regard, both simulation and ABC assist in analyzing the impact of the MHC
alternatives on the environment. Specifically, the amounts of energy and water consumed as well
as the amount of wastewater generated are determined for each MHC alternative. Environmental
costs that could not be quantified include wastewater treatment and solid waste disposal costs.
Also, the costs of defective boards and the consequent waste of resources were not quantified.
These costs are discussed in more detail, below.
4-27
-------
4.2 COST ANALYSIS
4-28
-------
4.2 COST ANALYSIS
i
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4-29
-------
4.2 COST ANALYSIS
Wastewater Treatment and Sludge Disposal Costs. PWB manufacturing consists of a
number of process steps (see Section 1.2.3 for an overview of rigid multi-layer PWB
manufacturing). In addition to the MHC process line, these steps include electroplating
operations and other steps which consume large quantities of rinse water and, consequently,
generate large quantities of wastewater. Most PWB manufacturers combine the effluents from
various process lines into one wastewater stream which is treated on-site in a continuous process
prior to discharge. As part of the Pollution Prevention and Control Survey (EPA, 1995a), PWB
manufacturers were asked to provide the following about their on-site wastewater treatment
facility:
• A process flow diagram for wastewater treatment.
• The quantity of sludge generated from wastewater treatment.
• The percent solids of the sludge.
• The costs of on-site wastewater treatment.
• The method and costs of sludge recycle and disposal.
Capital costs for wastewater treatment ranged from $1.2 million for a system purchased
in 1980 with a capacity of 135 gallons per minute (gpm) to $4,000 for a system purchased in
1987 with a capacity of nine gpm. Costs for operating an on-site wastewater treatment system
were as high as 3.1 percent of total annual sales. The median cost for wastewater treatment
operation was 0.83 percent and the average was 1.02 percent of annual sales.
Wastewater treatment sludges from PWB electroplating operations are classified as an
F006 hazardous waste under the Resources Conservation and Recovery Act (RCRA); most
facilities combine effluents from the electroplating line with other process wastewaters. Eighty-
eight percent of respondents to the Survey reported that wastewater treatment sludges are sent to
an off-site recycling facility to recover the metals. The average and median costs for off-site
recovery of sludge were $0.48/lb and $0.21/lb, respectively. In general, the lower costs
experienced by some respondents compared to others were due to larger-size shipments and
shorter distances to the recycling sites. In some cases, respondents whose sludge had a higher
solids content also reported lower costs; dewatered sludge has a higher recovery value.
Eighty-six percent of Survey respondents used an electroless copper MHC process, 14
percent used a palladium-based process (the Survey did not distinguish between tin- and organic-
palladium processes), and one respondent used a graphite process. None of the other MHC
alternatives were represented in the Survey.
The IPC Workplace Practices Questionnaire attempted to characterize costs by collecting
information about the percent the MHC line contributes to overall wastewater and sludge
generation rates. However, most manufacturers were unable to provide this information and the
data that were reported were of variable to poor quality.
Since the MHC line is only one of several process lines that discharge effluent to
wastewater treatment and because little or no information is available on the contribution of the
MHC line to overall wastewater effluents, on-site wastewater treatment and sludge disposal costs
could not be reliably estimated. However, costs of wastewater treatment and sludge disposal are
expected to differ significantly among the alternatives. For example, the presence of the chelator
—
-------
4.2 COST ANALYSIS
EDTA in electroless copper wastewater discharges makes these effluents more difficult to treat.
However, complexing agents, such as the ammonia found in other PWB manufacturing steps,
also adversely affect the treatability of wastewater.
Other Solid Waste Disposal Costs. Two other types of solid wastes were identified that
could have significantly different waste disposal costs among the alternatives: filter disposal cost
and defective boards disposal costs. Table 4.15 presents the number of filters that would be
replaced in each process during a job of 350,000 ssf. These data are based on data from the IPC
Workplace Practices Questionnaire and a UR calculated for each process from simulation results.
(Simulation results are discussed further in Section 4.2.2.) While these results illustrate that the
number of waste filters generated by the alternatives differ significantly, no information is
available on the characteristics of the filters used in alternative processes. For example, the
volume or mass of the filters and waste classification of the filters (hazardous or non-hazardous)
would significantly affect the unit cost for disposal. Therefore, filter disposal costs were not
estimated.
Table 4.15 Number of Filter Replacements by MHC Process
MHC Process
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Graphite, conveyorized
Conductive Polymer, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, convevorized
Filter Replacements
per Year*
100
100
20
103
74
17
50
50
74
74
Filter Replacements
per Job"
160
35
7
52
21
12
22
16
35
19
a 90th percentile data based on Workplace Practices Survey data. Data not adjusted for throughput or to account for
differing maintenance policies at individual PWB manufacturing facilities.
b Based on simulation results for a job of 3 50,000 ssf.
The number of defective boards produced by an alternative has significance not only from
the standpoint of quality costs, but also from the standpoint of waste disposal costs. Clearly, a
higher defect rate leads to higher scrap and, therefore, waste of resources. However, the
Performance Demonstration showed that each of the alternatives can perform as well as the
electroless copper process if operated according to specifications. Thus, for the purposes of this
analysis, no differences would be expected in the defect rate or associated costs of the
alternatives.
Simulation Model Assumptions and Input Values
Appendix G presents a graphic representation of the simulation models developed for
each of the MHC alternatives. The assumptions used to develop the simulation models and
model input values are discussed below.
4-31
-------
4.2 COST ANALYSIS
Assumptions. Several assumptions used in the simulation model are based on the
characteristics of a model facility presented in the Source Release Assessment and Exposure
Assessment (Sections 3.1 and 3.2, respectively). Assumptions include the following:
• The facility operates an MHC line 250 days/year, one shift/day. Many facilities operate
two shifts, but the Exposure Assessment and this analysis use first shift data as
representative. This assumption could tend to underestimate labor costs for companies
that pay higher rates to second shift workers. Or it could tend to overestimate equipment
costs for a company running two shifts and using equipment more efficiently. However,
since this assumption is used consistently across alternatives, the effects on the
comparative cost results are expected to be minor.
• The MHC process line operates an average of 6.8 hrs/shift.
• The MHC line is down at least 1.2 hours per day for start-up time and for maintenance,
including lubricating of equipment, sampling of baths, and filter replacement.
• Additional down time occurs when the MHC line is shut down to replace a spent or
contaminated bath.
• PWB panels that have been processed up to the MHC step are available whenever the
MHC process line is ready for panels.
• If a chemical bath is replaced at the end of the day, such that the amount of time required
to replace the bath exceeds the time remaining in the shift hours, employees will stay after
hours and have the bath ready by the beginning of the next shift.
• The entire MHC process line is shut down whenever a bath requires replacing, but
partially processed racks or panels are finished before the line is shut down.
• The MHC process only shuts down at the end of a shift and for bath replacement.
• The process is empty of all panels or racks at the end of each shift and starts the process
empty at the beginning of a shift.
Further simulation assumptions have to be defined separately for conveyorized and non-
conveyorized systems. Conveyorized MHC process assumptions are as follows:
• The size of a panel is 17.7" x 22.9" (from IPC Workplace Practices Questionnaire data for
conveyorized processes).
• Panels are placed on the conveyor whenever space on the conveyor is available, and each
panel requires 18" (including space between panels).
• Conveyor speed is constant, thus, the volume (gallons) of chemicals in a bath varies by
bath type (i.e., microetch, conditioner, etc.) and with the length of the process step (e.g.,
bath or rinse tank) to provide the necessary contact time (see Table 4.16 for bath
volumes).
• The conveyor speed, cycle time, and process down time are critical factors that determine
the time to complete a job.
4-32
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4.2 COST ANALYSIS
Table 4.16 Bath Volumes Used for Conveyorized Processes
Chemical Bath
Cleaner/Conditioner
Cleaner
Carbon
Graphite
Conditioner
Polymer
Microetch
Predip
Catalyst
Accelerator
Conductor
Electroless Copper
Post Dip
Acid Dip
Anti-Tarnish
Bath Volume by MHC Alternative (gallons)
Electroless
Copper
65
NA .
NA
NA
NA
•NA
64
50
139
80
NA
185
NA
79
39
Carbon
NA
44
128
NA
56
NA
64
NA
NA
NA
NA
NA
NA
NA
NA
Conductive
Polymer
65
NA
NA
NA
NA
26
64
NA
139
NA
NA
NA
NA
NA
NA
Graphite
65
NA
NA
37
NA
NA
64
NA
NA
NA
NA
NA
NA
NA
NA
Orgaaio*
Palladium
NA
44
NA
NA
56
NA
64
50
NA
NA
108
NA
45
79
NA
Tin-
Palladium
65
NA
NA
"NA
NA
NA
64
59
139
80
NA
NA
NA
79
NA
NA: Not Applicable.
Non-conveyorized MHC process assumptions are as follows:
• The average volume of a chemical bath is 75 gallons (from IPC Workplace Practices
Questionnaire data for non-conveyorized processes).
• Only one rack of panels can be placed in a bath at any one time.
• A rack contains 20 panels (based on IPC Workplace Practices Questionnaire data,
including the dimensions of a bath, the size of a panel, and the average distance between
panels in a rack).
• The size of apanel is 16.2" x 21.5" to give 96.8 ssf per rack.
• The frequency at which racks are entered into the process is dependent upon the
bottleneck or rate limiting step.
• The duration of the rate limiting step, cycle time, and process down time are critical
factors that determine the time to complete a job.
Inputs Values. Input values for the critical factors identified above (cycle time, down
time, and conveyor speed for conveyorized processes, and cycle tune, down time, and duration of
rate limiting step for non-conveyorized processes) were developed from IPC Workplace Practices
Questionnaire data and Product Data Sheets prepared by suppliers which describe how to mix
and maintain chemical baths. Tables 4.17 and 4.18 present time-related inputs to the simulation
models for non-conveyorized and conveyorized processes, respectively.
4-33
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4.2 COST ANALYSIS
Table 4.17 Time-Related Input Values for Non-Conveyorized Processes3
Non-Conveyorized
MHC Alternative
Electroless Copper
Non-Formaldehyde
Electroless Copper
Organic-Palladium
Tin-Palladium
Time Required to
Replace a Bathb
(minutes)
180
30
180
108
Raie Limiting
Bath
Electroless Copper
Electroless Copper
Accelerator
Conductor
Time in Rate
Limiting Bath"
(minutes)
34
16
9.2
5.3
Process Cycle
Time"
(minutes)
48
51
30
52
1 Values are averages or 90th percentile data from the IPC Workplace Practices Questionnaire and may represent
chemical products from more than one supplier. For example, five suppliers of electroless copper chemical products
participated in the project. Input values may underestimate or overestimate those of any one facility, depending on
factors such as individual operating procedures, the chemical or equipment supplier, and the chemical product used.
b 90th percentile value used in the Exposure Assessment from IPC Workplace Practices Questionnaire data (see
Section 3.2). Used to calculate down time.
c Average values from the IPC Workplace Practices Questionnaire.
Table 4.18 Time-Related Input Values for Conveyorized Processes3
Conveyorized MHC
Alternative
Electroless Copper
Carbon
Conductive Polymer
Graphite
Organic-Palladium
Tin-Palladium
Time Required to
Replace a Bathb
(minutes)
180
180
180
219
108
180
Length of
Conveyor'
(feet)
71
31
34
27
50
47
Process Cycle
Time*
(minutes)
15
13
8.0
7.8
15
8.6
Conveyor
Speed*
(ft/min)
4.7
2.4
4.3
3.5
3.3
5.5
* Values are averages or 90th percentile data from the IPC Workplace Practices Questionnaire and may represent
chemical products from more than one supplier. For example, five suppliers of electroless copper chemical products
participated in the project. Input values may underestimate or overestimate those of any one facility, depending on
factors such as individual operating procedures, the chemical or equipment supplier, and the chemical product used.
b 90th percentile value used in the Exposure Assessment from IPC Workplace Practices Questionnaire data (see
Section 3.2). Used to calculate down time.
c Average values from IPC Workplace Practices Questionnaire.
d Conveyor speed = length of conveyor •*• process cycle time.
The input values for the time required to replace a bath time (in Tables 4.17 and 4.18) are
used together with bath replacement criteria in the calculation of down time. Suppliers provide
instructions with their products (called Product Data Sheets for the purposes of this project) that
describe when a bath should be replaced because it is expected to be spent or too contaminated to
be used. These replacement criteria are usually given in one of three forms:
• As a bath capacity in units of ssf per gallon of bath.
• As a concentration-based criterion that specifies an upper concentration limit for
contaminants in the bath, such as grams of copper per liter in the microetch bath.
• As elapsed time since bath creation.
4-34
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4.2 COST ANALYSIS
Bath replacement criteria submitted by suppliers were supplemented with IPC Workplace
Practices Questionnaire data and reviewed to determine average criteria for use in the simulation
models. Criteria in units of ssf/gallon were preferred because these can be correlated directly to
the volume of a bath. Once criteria in ssf/gallon were determined, these were converted to units
of racks per bath replacement for non-conveyorized processes and panels per bath replacement
for conveyorized processes. The converted values were used as inputs to the simulation models.
As an example, Table 4.19 presents bath replacement criteria used to calculate input values for
electroless copper processes. Appendix G presents the different bath replacement criteria
recommended by chemical suppliers, and the input values used in this analysis.
Table 4.19 Bath Replacement Criteria for Electroless Copper Processes
Chemical Bath
Cleaner/Conditioner
Microetch
Predip
Catalyst
Accelerator
Electroless Copper
Acid Dip
Anti-Tarnish
Bath Replacement Criteria"
(ssf/gal)
510
250
540
Replace once per year
280
430
675
325
Values were selected from data provided by more than one electroless copper chemical supplier. To convert to
units of racks per bath replacement for non-conveyorized processes, multiply by 75 gallons (the average bath size)
and divide by 96.8 ssf (ssf per rack). To convert to units of panels per bath replacement for conveyorized processes,
multiply by the bath size in gallons and divide by 5.6 ssf/panel.
Activity-Based Costing (ABC)
As discussed previously, ABC is a method of allocating indirect or overhead costs to the
products or processes that actually incur those costs. Activity-based costs are determined by
developing BOAs for critical tasks. A BOA is a listing of the component activities involved in
the performance of a certain task, together with the number of times each component activity is
performed. The BOA determines the cost of a task by considering the sequence of actions and
the resources utilized while performing that task. In this analysis, the costs of critical tasks
determined by a BOA are combined with the number of tunes a critical task is performed,
derived from simulation results to determine the total costs of that activity.
BOAs were developed for the following critical tasks performed within MHC
alternatives:
Chemical transport from storage to the MHC process.
Tank cleanup.
Bath setup.
Bath sampling and analysis.
Filter replacement.
4-35
-------
4.2 COST ANALYSIS
These BOAs were developed based on information developed for earlier projects
involving similar tasks and on information gathered through site visits and general process
knowledge. The following discussion uses the BOA for chemical transport, presented in Table
4.20, as an example of how BOAs were developed and used. Appendix G presents the BOAs for
other activities.
Key assumptions were developed to set the limits and to designate the critical activity's
characteristics. For chemical transport, the assumptions were:
Chemical costs are not included in the BOA, but are considered within material costs.
• The portion of labor costs considered are not included within production costs.
• Labor rate used is $10.22 per hour, consistent with the labor rate for an operator level job.
• Multiple chemicals are required for each bath replacement.
• All chemicals for a bath replacement are transported on one forklift trip.
• Chemicals are purchased in containers larger than the line containers used to move
chemicals to the MHC process.
• All chemicals are stored in a central storage location.
• Chemicals are maintained in central storage via inventory tracking and physical
monitoring.
A forklift costs $580/month or $0.06/minute, including leasing, maintenance, and fuel.
• Forklifts are utilized to move all chemicals.
• Forklifts are parked in an assigned area when not in use.
Each critical task was broken down into primary and secondary activities. For chemical
transport, the six primary activities are: paperwork associated with chemical transfer, moving
forklift to chemical storage area, locating chemicals in storage area, preparation of chemicals for
transfer, transporting chemicals to MHC process, and transporting chemicals from MHC process
to actual bath. The secondary activities for the primary activity of "transport chemicals to MHC
process" are: move forklift with chemicals, unload line containers, and park forklift in assigned
parking area. For each secondary activity the labor, material, and forklift costs are calculated.
The sum of the costs of a set of secondary activities equals the cost of the primary activity. The
forklift costs are a function of the time that labor and the forklift are used.
For example, for a chemical transport activity that requires two minutes, the labor cost is
$0.34 (based on a labor rate of $10.22 per hour) and the forklift cost is $0.12 (based on $0.06 per
minute). Materials costs are determined for materials other than chemicals and tools required for
an activity. The total of $9.11 in Table 4.20 represents the cost of a single act of transporting
chemicals to the MHC line. The same BOAs are used for all MHC technologies because either
the activities are similar over all MHC technologies or information is unavailable to distinguish
among the technologies. However, individual facilities could modify a BOA to best represent
their unique situations. Table 4.21 presents costs to perform each of the critical tasks one time.
4-36
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4.2 COST ANALYSIS
Table 4.20 BO As for Transportation of Chemicals to MHC Line
Activities
t
A. Paperwork and Maintenance
1. Request for chemicals
2. Updating inventory logs
3. Safety and environmental record keeping
B. Move Forklift to Chemical Storage Area
1 . Move to forklift parking area
2. Prepare forklift to move chemicals
3. Move to line container storage area
4. Prepare forklift to move line container
5. Move forklift to chemical storage area
C. Locate Chemicals in Storage Area
1 . Move forklift to appropriate areas
2. Move chemical containers from storage to
staging
3. Move containers from staging to storage
D. Preparation of Chemicals for Transfer
1. Open chemical container(s)
2. Utilize correct tools to obtain chemicals
3. Place obtained chemicals in line containers)
4. Close chemical container(s)
5. Place line container(s) on forklift
E. Transport Chemicals to Line
1. Move forklift to line
2. Unload line containers) at line
3. Move forklift to parking area
F. Transport Chemicals from Line to Bath
1. Move line containers) to bath
2. Clean line container(s)
3. Store line container(s) in appropriate area
Time
(nritt)
2
1
2
2
5
2
3
2
1
2
2
1
3
3
1.5
1
2
1
2
1
2
1
Resources
Labor"
$0.34
$0.17
$0.34
$0.34
$0.85
$0.34
$0.51
$0.34
$0.17
$0.34
$0.34
$0.17
$0.51
$0.51
$0.09
$0.17
$0.34
$0.17
$0.34
$0.17
$0.34
$0.17
Materials'1
$0.10
$0.05
$0.10
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.05
$0.05
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.20
$0.00
Forkliff
$0.00
$0.00
$0.00
$0.12
$0.30
$0.12
$0.18
$0.12
$0.06
$0.12
$0.12
$0.00
$0.00
$0.00
$0.00
$0.06
$0.12
$0.06
$0.12
$0.00
$0.00
$0.00
Total Cost per Transport
Cost
(S/transport)
$0.44
$0.22
$0.44
$0.46
$1.15
$0.46
$0.69
$0.46
$0.23
$0.46
$0.46
$0.22
$0.56
$0.51
$0.09
$0.23
$0.46
$0.23
$0.46
$0.17
$0.54
$0.17
$9.11
" Labor rate = $10.22 per hour.
b Materials do not include chemicals or tools.
c Forklift operating cost = $0.06 per minute.
4-37
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4.2 COST ANALYSIS
Table 4.21 Costs of Critical Tasks
Task
Cost
Transportation of Chemicals
$9.11
Tank Cleanup
$67.00
Bath Setup
$15.10
Sampling and Analysis
$3.70
Filter Replacement
$17.50
Fundamental Principles of Cost Analysis
Previous studies have defined seven principles of a fundamentally sound cost analysis
(DeGamo et al., 1996), listed below. This analysis was designed to strictly adhere to these
fundamental principles to increase the validity and credibility of the cost formulation.
Principle 1. Develop the alternatives to be considered: Table 4.13 identified the
MHC technologies and equipment configurations considered in the cost analysis. Figure 4.13
listed the generic process steps and typical bath sequences for each of these technologies. These
process steps and bath sequences are used consistently throughout the CTSA.
Principle 2. Focus on the difference between expected future outcomes among
alternatives: Costs that are the same among all technologies do not need to be considered as
there is no difference among alternatives for these costs. However, all costs that differ should be
considered, provided the costs can be reliably estimated. Costs quantified in this analysis are
capital costs, material costs, utility costs, wastewater costs, production costs, and maintenance
costs. These cost categories were summarized earlier in this section and are discussed in more
detail in Section 4.2.3.
Other cost categories are expected to differ in the future outcomes, but cannot be reliably
estimated. These include waste treatment and disposal costs and quality costs. These costs were
considered qualitatively earlier in this section.
Principle 3. Use a consistent viewpoint: The costs to produce a job consisting of
350,000 ssf are estimated for each technology and equipment configuration. Efficient MHC
technologies with the ability to produce the 350,000 ssf quicker are rewarded by having the cost
rates (i.e., $/hr, etc.) of certain costs held constant, but the overall cost is calculated over a
proportionally shorter time period. For example, if labor rates and the number of workers per
day are the same, a process that takes 50 percent less time than the baseline to complete a job
will have 50 percent lower labor costs than the baseline.
Principle 4. Use a common unit of measurement: Costs are normalized to a common
unit of measurement, $/ssf, to compare the relative costs of technologies.
Principle 5. Consider all relevant criteria: A thorough cost analysis requires the
consideration of all criteria relevant to the overall costs of the technologies. The costs considered
hi this analysis were defined earlier in this section and are discussed in more detail in Section
4.2.3.
4-38
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4.2 COST ANALYSIS
Principle 6. Make uncertainty explicit: Uncertainty is inherent in projecting the future
outcomes of the alternatives and should be recognized in the cost analysis. Sensitivity analysis
techniques are utilized to evaluate the effects of critical variables on cost.
Principle 7. Examine the analysis for accuracy: The cost analysis has been peer
reviewed by industry, EPA, and other stakeholders to assess its accuracy and validity.
4.2.2 Simulation Results
Simulation models were run for each of the MHC processes. Three types of simulation
outputs were obtained for use in the cost analysis:
• The duration and frequency of bath replacements.
• The production time required for each process.
• Down time incurred in producing 350,000 ssf.
The baseline process is used below as an example to explain the results of the simulation.
Table 4.22 presents the bath replacement simulation outputs. The values in the table
represent the actual average time for bath replacement for the baseline process. Reviewing the
table reveals that the cleaner/conditioner bath requires replacement nine times. Each replacement
takes an average of 133 minutes. The total replacement time represents the total time the process
is down due to bath replacements. Summing over all baths, bath replacement consumes 179
hours (10,760 minutes) when using the non-conveyorized electroless copper process to produce
350,000 ssf. Bath replacement simulation outputs for the other MHC processes are presented in
Appendix G.
Table 4.22 Example Simulation Output for Non-Conveyorized Electroless Copper Process:
Frequency and Duration of Bath Replacements
Chemical Bath
Cleaner/Conditioner
Microetch
Predip
Catalyst
Accelerator
Electroless Copper
Acid Dip
Anti-Tarnish
Total
Frequency
9
18
8
1
16
10
6
13
81
Avg, Time/Replacement
(minutes)
138
146
125
230
130
114
146
120
133
Total Time
(minutes)
1,240
2,630
1,000
230
2,080
1,140
876
1,560
10,760
As shown in the example, the bath replacement output value may be more than or less
than the bath replacement input values reported in Tables 4.17 and 4.18. In this case, the input
value for non-conveyorized electroless copper processes is 180 minutes, but the output values
range from 114 to 230 minutes. Bath maintenance output values are less than input values when,
on average, the bath is shut down with less than 180 minutes remaining in the shift. Under this
4-39
-------
4.2 COST ANALYSIS
scenario, the simulation model assumes that the employee will sjtay on past the end of the shift to
complete the bath replacement. Thus, only the time remaining in a normal 8-hour shift is
charged to down time.
Alternately, bath maintenance output values may be greater than input values if more than
180 minutes remain in the shift when the bath is shut down. In this case, the simulation model
assumes that all racks or panels will clear the system prior to shutting down the line for a bath
replacement. Thus, bath replacement times greater than 180 minutes account for the cycle time
required for racks and/or panels to clear the system.
Table 4.23 presents the second and third types of simulation output, the total production
time required for each process, and the down time incurred by each process in producing 350,000
ssf. Total production tune is the sum of actual operating time and down time. Down time
includes the 1.2 hours per day the line is assumed inactive plus the time the process is down for
bath replacements. Again, actual simulation outputs are presented in Appendix G.
Table 4.23 Production Time and Down Time for MHC Processes to Produce 350,000 ssf
MHC Process
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper,
non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin Palladium, conveyorized
Total Production Time*
minutes
163,500
36,100
50,800
29,100
33,400
74,600
31,800
45,300
48,500
26,100
days
401
88.4
125
71.3
82.0
183
77.9
111
119
63.9
Total Down Time"
minutes
33,900
16,300
11,800
7,110
6,490
16,400
10,800
18,000
13,600
9,010
days
83.2
40.0
28.9
17.4
15.9
40.1
26.4
44.1
33.4
22.1
To convert from minutes to days, divide by 6.8 hrs per day (408 minutes)
4.2.3 Cost Formulation Details and Sample Calculations
This section develops and describes in detail the cost formulation used for evaluating the
MHC processes. The overall cost was calculated from individual cost categories that are
common to, but expected to vary with, the MHC process alternatives. The cost model was
validated by cross-referencing the cost categories with Tellus Institute (White et al., 1992), and
Pacific Northwest Pollution Prevention Research Center (Badgett et al., 1995).
The cost model for an MHC alternative is as follows:
TC=
WW
MA
4-40
-------
4.2 COST ANALYSIS
where:
TC = total cost to produce 350,000 ssf
C = capital cost
M = material cost
U = utility cost
WW = wastewater cost
P = production cost
MA = maintenance cost
The unit cost of producing 350,000 ssf is then represented as follows:
Unit Cost ($/ssf) = TC ($) / 350,000 ssf
The following sections presents a detailed description of cost calculation methods
together with sample calculations for the baseline non-conveyorized electroless copper process.
Finally, the results of the sample calculations are summarized and then combined to calculate the
total cost and unit cost for the non-conveyorized electroless copper process.
Capital Costs
This section presents methods and sample calculations for calculating capital costs.
Capital costs are one-time or periodic costs incurred in the purchase of equipment or facilities. In
this analysis, capital costs include the costs of primary equipment, equipment installation, and
facility space utilized by the process. Primary equipment is the equipment vital to the operation
of the MHC process without which the process would not be able to operate (i.e., bath tanks,
heaters, rinse water system, etc.). Installation costs include costs to install the process equipment
and prepare it for production. Facility space is the floor space required to operate the MHC
process.
Total capital costs for the MHC technologies were calculated as follows:
C = (E + I + F)xUR
where:
E = annualized capital cost of equipment ($/yr)
I = annualized capital cost of installation ($/yr)
F = annualized capital cost of facility ($/yr)
UR = utilization ratio, defined as the time in days required to manufacture 350,000
ssf divided by one operating year (250 days)
The UR adjusts annualized costs for the amount of time required to process 350,000 ssf,
determined from the simulation models of each process alternative. The components of capital
costs are discussed further below followed by sample calculations of capital costs.
Equipment and Installation Costs. Primary equipment and installation costs estimates
were provided by equipment suppliers and include delivery of equipment and sales tax.
Equipment estimates were based on basic, no frills equipment capable of processing 100
-------
4.2 COST ANALYSIS
panels/hr. Equipment estimates did not include auxiliary equipment such as statistical process
control or automated sampling equipment sometimes found on MHC process lines.
Annual costs for both the equipment and installation costs were calculated assuming 10-
year, straight-line depreciation of equipment and no salvage value. These annual costs were
calculated using the following equations:
E = equipment cost ($) •*• 10 years
I = installation cost ($) •*• 10 years
Facility Costs. Facility costs are capital costs for the floor space required to operate the
MHC line. Facility costs were calculated assuming industrial floor space costs $65/ft2 and the
facility is depreciated over 25 years using straight-line depreciation. The cost per square foot of
floor space applies to Class A light manufacturing buildings with basements. This value was
obtained from the Marshall Valuation Service (Vishanoff, 1995) and mean square foot costs
(Ferguson, 1996). Facility costs were calculated using the following equation:
F = [unit cost of facility utilized ($/ft2) x footprint area/process step (ftVstep)
x number of steps] •*• 25 years
The "footprint area" is the area of floor space required by MHC equipment, plus a buffer
zone to maneuver equipment or have room to work on the MHC process line.1 The footprint area
per process step was calculated by determining the footprint dimensions of each process
alternative, adjusting the dimensions for working space, and then determining the area per
process step. Because the footprint area depends on the type of process automation, the average
dimensions of both conveyorized (5 ft x 38 ft) and non-conveyorized (6 ft x 45 ft) processes were
determined from IPC Workplace Practices Questionnaire data. Since these dimensions account
for the equipment footprint only, an additional 8 ft was added to every dimension to allow space
for line operation, maintenance, and chemical handling. The floor space required by either
equipment type was calculated (1,134 ft2 for conveyorized processes and 1,342 ft2 for non-
conveyorized processes) and used to determine the area required per process step. This was done
by first identifying the process alternative with the fewest process steps for each automation type,
and then dividing the required floor space by that number of steps. This method conservatively
estimated the amount of floor space required per process step for conveyorized processes at 160
ftVstep and for non-conveyorized processes at 110 ft2/step. The overall area required for each
MHC alternative was then calculated using the following equations:
Conveyorized:
Fc = [$65/ft2 x 160 ft2/step x number of steps per process] -5- 25 years
Non-conveyorized:
FN = [$65/ft2 x 110 ftVstep x number of steps per process] -*- 25 years
1 PWB manufacturers and their suppliers use the term "footprint" to refer to the dimensions of process
equipment, such as the dimensions of the MHC process line.
~~""~' 442
-------
4.2 COST ANALYSIS
Sample Capital Costs Calculations. This section presents sample capital costs
calculations for the baseline process. From Figure 4.13, the non-conveyorized electroless copper
process consists of 19 chemical bath and rinse steps. Simulation outputs in Table 4.23 indicate
this process takes 401 days to manufacture 350,000 ssf of PWB. Equipment vendors estimated
equipment and installation costs at $400,000 and $70,000, respectively (Microplate, 1996;
Coates ASI, 1996; PAL Inc., 1996; Circuit Chemistry, 1996; Western Technology Associates,
1996). The components of capital costs are calculated as follows:
E = $400,000 -s-10 yrs = $40,000/yr
I = $70,000 - 10 yrs = $7,000/yr
FN = ($657^ x 110 ftVstep x 19 steps) - 25 yrs = $5,430/yr
UR =401 days •*- 250 days/yr = 1.60 yrs
Thus, the capital costs for the non-conveyorized electroless copper process to produce
350,000 ssf of PWB are as follows:
C = ($40,000/yr + $7,000/yr + $5,430/yr) x 1.60 yrs = $83,900
Materials Costs
Materials costs were calculated for the chemical products consumed in MHC process
lines through the initial setup and subsequent replacement of process chemical baths. The
following presents equations for calculating materials costs and sample materials cost
calculations for the baseline process.
Materials Cost Calculation Methods. Chemical suppliers were asked to provide
estimates of chemical costs ($/ssf) early in the project. While some suppliers furnished estimates
for one or more of their process alternatives, several suppliers did not provide chemical cost
estimates for all of their MHC process lines being evaluated. Still others provided incomplete
cost estimates or did not provide any supporting documentation of assumptions used to estimate
chemical costs. Therefore, these data could not be used in the comparative cost estimates.
Instead, chemical costs were estimated using the methods detailed below.
Chemical baths are typically made-up of one or more separate chemical products mixed
together at specific concentrations to form a chemical solution. As PWBs are processed by the
MHC line, the chemical baths become contaminated or depleted and require chemical additions
on replacement. Baths are typically replaced according to analytical results or by supplier
recommended replacement criteria specific to each bath. When the criteria are met or exceeded,
the spent bath is removed and a new bath is created. The chemical cost to replace a specific bath
one time is the sum of the costs of each chemical product in the bath and is given by the
following equation:
Chemical cost/bath replacement = Ej [chemical product cost/bath ($/gal) x % chemical product
in bath x total volume of bath (gal)]
where:
= number of chemical products in a bath
4-43
-------
4.2 COST ANALYSIS
The University of Tennessee Department of Industrial Engineering contacted suppliers to
obtain price quotes in $/gallon or $/lb for MHC chemical products. The compositions of the
individual process baths were determined from Product Data Sheets for each bath. The average
volume of a chemical bath for non-conveyorized processes was calculated to be 75 gallons from
IPC Workplace Practices Questionnaire data. For conveyorized processes, however, conveyor
speed is constant, thus, the volume of chemicals in a bath varies by bath type to provide the
necessary contact time (see Table 4.16 for conveyorized process bath volumes). These data were
used in the above equation to calculate the chemical cost per bath replacement for each product
line. The bath replacement costs were then averaged across like product lines (i.e., chemical
costs from various suppliers of electroless copper processes were averaged by bath type, etc.) to
determine an average chemical cost per replacement for each process bath.
To obtain the total materials cost, the chemical cost per bath replacement for each bath
was multiplied by the number of bath replacements required (determined by simulation) and then
summed over all the baths in an alternative. The cost of chemical additions was not included
since no data were available to determine the amount and frequency of chemical additions.
Materials costs are given by the following equation:
M = Ej [chemical cost/bath replacement ($)x number of replacements/bath]
where:
J
= number of baths in a process
The frequency of replacement for individual process baths was determined using supplier
recommended criteria provided on Product Data Sheets and from IPC Workplace Practices
Questionnaire data. Simulation models were used to determine the number of times a bath
would be replaced while an MHC line processes 350,000 ssf of PWB. Appendix G presents bath
replacement criteria used in this analysis and summaries of chemical product cost by supplier and
by MHC technology.
Sample Materials Cost Calculations. Table 4.24 presents an example of chemical costs
per bath replacement for one supplier's electroless copper line. Similar costs are presented in
Appendix G for the six electroless copper chemical product lines evaluated. The chemical costs
per process bath for all six processes were averaged to determine the average chemical cost per
bath for the non-conveyorized electroless copper process.
The chemical cost per bath was then calculated by multiplying the average chemical cost
for a bath by the number of bath replacements required to process 350,000 ssf. The costs for
each bath were then summed to give the total materials cost for the overall non-conveyorized
electroless copper process. Table 4.25 presents the chemical cost per bath replacement, the
number of bath replacements required as determined by simulation, the total chemical cost per
bath, and the total material cost for the non-conveyorized electroless copper process. Similar
material cost calculations for each of the MHC process alternatives are presented in Appendix G.
4-44
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4.2 COST ANALYSIS
Table 4.24 Chemical Cost per Bath Replacement for One Supplier of the
Non-Conveyorized Electroless Copper Process
Bath
^
Cleaner/Conditioner
Microetch
Predip
Catalyst
Accelerator
Electroless Copper
Neutralizer
Anti-Tarnish
Chemical ;
Product
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
Product
Cosecs)
$25.45/gal
$2.57/lb
$7.62/gal
$1.60/gal
$1.31/lb
$2.00/gal
$391.80/gal
$1.31/lb
$2.00/gal
$18.10/gal
$27.60/lb
$16.45/gal
$4.50/gal
$1.60/gal
$39.00/gal
Percentage of
Chemical Product1*
6
13.8 g/1
2.5
18.5
31.7 g/1
1.5
4
0.17 g/1
3.5
» 20
7
8.5
0.22
100
0.25
Chemical Cost/Bath
Replacement6 ($)
$115
$59
$22
$1,186
$273
$252
$120
$7
1 Product cost from supplier of the chemical product.
b The percentage of a chemical product in each process bath was determined from Product Data Sheets provided by
the supplier of the chemical product.
c Cost per bath calculated assuming bath volumes of 75 gallons.
Table 4.25 Materials Cost for the Non-Conveyorized Electroless Copper Process
Bath
Cleaner/Conditioner
Microetch
Predip
Catalyst
Accelerator
Electroless Copper
Neutralizer
Anti-Tarnish
Chemical Cost/Bath
Replacement*
$188
$66
$340
$1,320
$718
$317
$120
$16
Number of Bath
Replacements"
9
18
8
1
16
10
6
13
Total
Chemical Cost
$1,690
$1,190
$2,720
$1,320
$11,500
$3,170
$720
$208
Total Materials Cost $22,500°
Reported data represents the chemical cost per bath replacement averaged over six electroless copper product
lines.
b Number of bath replacements required to process 350,000 ssf determined by simulation.
c Does not include cost of chemical additions.
4-45
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4.2 COST ANALYSIS
Utility Costs
Utility costs for the MHC process include water consumed by rinse tanks,2 electricity
used to power the panel transportation system, heaters and other process equipment, and natural
gas consumed by drying ovens employed by some MHC alternatives. The utility cost for the
MHC process was determined as follows:
U
= W + E + G
where:
W = cost of water consumed ($/ssf) to produce 350,000 ssf
E = cost of electricity consumed ($/ssf) to produce 350,000 ssf
G = cost of natural gas consumed ($/ssf) to produce 350,000 ssf
The following presents utility costs calculation methods and sample utility costs for the
baseline process.
Utility Cost Calculation Methods. The rate of water consumption depends on both the
number of distinct water rinse steps and the flow rate of the water in those steps. The typical
number of water rinse steps for each MHC alternative was determined using supplier provided
data together with data from the IPC Workplace Practices Questionnaire. Cascaded rinse steps
were considered as one rinse step when calculating water consumption since the cascaded rinse
steps all utilize the same water. Based on IPC Workplace Practices Questionnaire data, the
average water flow rate for individual rinse steps was estimated at 1,185 gals/tank for
conveyorized processes and 1,840 gals/tank for non-conveyorized processes. However, it was
assumed that the rinse steps are shut off during periods of process down time. Therefore, daily
water consumption rates were adjusted for the percentage of time the process was in operation.
The cost of water was calculated by multiplying the water consumption rate of the MHC
process by the production time required to produce 350,000 ssf of PWB, and then applying a unit
cost factor to the total. Water consumption rates for MHC alternatives are presented in Section
5.1, Resource Conservation, while production times were determined from the simulation
models. A unit cost of $1.60/1,000 gallons of water was obtained from the Pollution Prevention
and Control Survey (EPA, 1995a). Following is the equation for calculating water cost:
W = quantity of rinse water consumed (gal) x $1.60/1,000 gal
The rate of electricity consumption for each MHC alternative depends upon the
equipment required to operate each alternative. Differences in required process equipment such
as the number of heaters, pumps, and type and extent of panel agitation directly affect electricity
consumption. The cost of electricity is calculated by multiplying the electricity consumption rate
of the MHC process by the production time required to produce 350,000 ssf of PWB, and then
applying a unit cost factor to the total. Electricity consumption rates for MHC alternatives are
2 Water is also used in MHC chemical baths to dilute chemical products to the appropriate concentration,
but this use of water was assumed negligible compared to the water consumed in rinse tanks.
_ -—
-------
4.2 COST ANALYSIS
presented in Section 5.2, Energy Impacts, while the required production time was determined by
simulation. A unit cost of $0.0473/kW-hr was obtained from the International Energy Agency.
Therefore, the energy cost was calculated using the following equation:
E = hourly consumption rate (kW) x required production time (hrs) x
$0.0473/kW-hr
Natural gas is utilized to fire the drying ovens required by both the graphite and carbon
MHC alternatives. The amount of gas consumed was determined by multiplying the natural gas
consumption rate for the MHC process by the amount of operating time required by the process
to produce 350,000 ssf of PWB and then applying a unit cost to the result. Knoxville Utilities
Board (KUB) charges $0.3683 per therm of natural gas consumed (KUB, 1996a). Thus, the cost
of natural gas consumption was calculated by the following equation:
G = natural gas consumption rate (therm/hr) x required production time (hrs) x
$0.3683/therm
The graphite process typically requires a single drying stage while the carbon process
requires two drying oven stages. Natural gas consumption rates hi cubic feet per hour for both
carbon (180 cu.ft./hr) and graphite (90 cu.ft./hr) processes were obtained from Section 5.2,
Energy Impacts. The production time required to produce 350,000 ssf of PWB came from
simulation results.
Sample Utility Cost Calculations. The above methodology was used to calculate the
utility costs for each of the MHC alternatives. This section presents sample utility cost
calculations for the non-conveyorized electroless copper process.
Simulation results indicate the non-conveyorized electroless copper process is down 83.2
days and takes 401 days overall (at 6.8 hrs/day) to produce 350,000 ssf. It is comprised of seven
rinse steps which consume approximately 4.1 million gallons of water during the course of the
job (see Section 5.1, Resource Conservation). Electricity is consumed at a rate of 27.2 kW/hr
(see Section 5.2, Energy Impacts). The non-conveyorized electroless copper process has no
drying ovens and, therefore, does not use natural gas. Based on this information, water,
electricity, and gas costs were calculated as follows:
W =4,089,000 gallons x $ 1.60/1,000 gals = $6,540
E = 27.2 kW x (401 days-83.2 days) x 6.8 hrs/day x $.0473/kW-hr = $2,780
G = $0
Thus, the utility cost for the non-conveyorized electroless copper process was determined
by the calculation:
U = $6,540 + $2,780 + $0 = $9,320
4-47
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4.2 COST ANALYSIS
Wastewater Costs
Wastewater Cost Calculation Methods. Wastewater costs for the MHC processes were
only determined for the cost of discharging wastewater to a POTW. The analysis assumes that
discharges are made in compliance with local allowable limits for chemical concentrations and
other parameters so that no fines are incurred.
Wastewater quantities were assumed equal to the quantity of rinse water used. Rinse
water usage was calculated in Section 5.1, Resource Conservation, and used to calculate water
costs in the Utility Costs section. The unit costs for fees charged by a POTW for both city and
non-city discharges of wastewater were obtained from KUB and averaged for use in calculating
wastewater cost (KUB, 1996b). These average unit costs are not flat rates applied to the total
wastewater discharge, but rather combine to form a tiered cost scale that applies an incremental
unit cost to each level of discharge. The tiered cost scale for wastewater discharges to a POTW
is presented in Table 4.26.
Table 4.26 Tiered Cost Scale for Monthly Wastewater Discharges to a POTW
Wastewater Discharge
Quantity
(ccf/month)
0-2
3-10
11-100
101-400
401 - 5,000
City Discharge
Cost
($/ce£/inonth)
$6.30
$2.92
$2.59
$2.22
$1.85
Non-City
Discharge Cost
($/ce#month)
$7.40
$3.21
$2.85
$2.44
$2.05
Average Discharge
Cost
($/ccf/month)
$6.85
$3.06
$2.72
$2.33
$1.95
Source: KUB, 1996b.
ccf: 100 cubic ft.
The unit costs displayed for each level of discharge are applied incrementally to the
quantity of monthly discharge. For example, the first two cubic feet of wastewater discharged in
a month are assessed a charge of $6.85, while the next eight cubic feet cost $3.06, and so on.
The production time required to produce 350,000 ssf of PWB comes from the simulation models.
Thus, wastewater costs were calculated as follows:
WW = E; [quantity of discharge in tier (ccf/mo) x tier cost factor ($/ccf)] x required
production time (months)
where:
i = number of cost tiers
ccf = 100 cubic ft
Sample Wastewater Cost Calculations. This section presents sample wastewater
calculations for the non-conveyorized electroless copper process. Based on rinse water usage,
the total wastewater release was approximately 4.1 million gallons. The required production
time in months was calculated using the required production time from Table 4.23 and a 250 day
operating year (401 days + 250 days/year x 12 months/yr = 19.2 months). Thus, the monthly
4-48
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4.2 COST ANALYSIS
wastewater release was 285 ccf (4,089,000 gallons -K19.2 months - 748 gal/hundred cu ft). To
calculate the wastewater cost for the non-conveyorized electroless copper process, the tiered cost
scale was applied to the quantity of discharge and the resulting costs per tier were summed, as
follows:
$6.85 x 2 ccf/month = $13.70 ccf/month
$3.06 x 8 ccf/month = $24.48 ccf/month
$2.72 x 90 ccf/month = $245 ccf/month
$2.33 x 185 ccf/month = $431 ccf/month
Monthly discharge cost = $13.70+ $24.48+ $245+ $431 = $714/month
The monthly cost was then multiplied by the number of months required to produce
350,000 ssf of PWB to calculate the overall wastewater treatment cost:
WW = $714/monthx 19.2 month = $13,700
Production Costs
Production Cost Calculation Methods. Production costs for the MHC process include
both the cost of labor required to operate the process and the cost of transporting chemicals to the
production line from storage. Production costs were calculated by the following equation:
where:
LA
TR
= LA + TR
= production labor cost ($/ssf) to produce 350,000 ssf
= chemical transportation cost ($/ssf) to produce 350,000 ssf
Production labor cost is a function of the number and type of employees and the length of
time required to complete a job. The calculation of production labor cost assumes that line
operators perform all of the daily activities, excluding bath maintenance, vital to the operation of
the MHC process. Labor costs associated with bath maintenance activities, such as sampling and
analysis, are presented in the discussion of maintenance costs, below. An average number of line
operators was determined for both conveyorized (one line operator) and non-conveyorized (1.1
line operators) processes from IPC Workplace Practices Questionnaire data and supported by site
visit observations. Although no significant difference in the number of line operators by
automation type was reported in the data, the number of line operators for non-conveyorized
processes was adjusted upward to 1.1 to reflect the greater level of labor content for these
processes as compared to conveyorized processes.
The labor time required to complete the specified job (350,000 ssf) was calculated
assuming an average shift time of eight hours per day and using the number of days required to
produce 350,000 ssf of PWB from simulation results. A labor wage of $10.22/hr was obtained
from the American Wages and Salary Survey (Fisher, 1995) and utilized for MHC line operators.
Therefore, labor costs for MHC alternatives were calculated as follows:
4-49
-------
4.2 COST ANALYSIS
LA = number of operators x $ 10.22/hr x 8 hrs/day x required production
time (days)
The production cost category of chemical transportation cost includes the cost of
transporting chemicals from storage to the MHC process line. A BOA, presented in Appendix G,
was developed and used to calculate the unit cost per chemical transport. Since chemicals are
consumed whenever a bath is replaced, the number of trips required to supply the process line
with chemicals equals the number of bath replacements required to produce 350,000 ssf of PWB.
Chemical transportation cost was calculated as follows:
TR = number of bath replacements x unit cost per chemical transport ($)
Sample Production Cost Calculations. For the example of the non-conveyorized
electroless copper process, production labor cost was calculated assuming 1.1 operators working
for 401 days (see Table 4.23). Chemical transportation cost was calculated based on a cost per
chemical transport of $9.11 (see Table 4.20 and Appendix G) and 81 bath replacements (see
Table 4.22). Thus, the production cost was calculated as follows:
LA = 1.1 x $10.22 x 8 hrs/day x 401 days = $36,100
TR = 81 x $9.11 = $737
thus:
= $36,100+ $737 = $36,800
Maintenance Costs
Maintenance Costs Calculation Methods. The maintenance costs for the MHC process
include the costs associated with tank cleaning, bath setup, sampling and analysis of bath
chemistries, and bath filter replacement. Maintenance costs were calculated as follows:
MA =
where:
TC = tank cleanup cost ($/ssf) to produce 350,000 ssf
BS = bath setup cost ($/ssf) to produce 350,000 ssf
FR = filter replacement cost ($/ssf) to produce 350,000 ssf
ST = sampling cost ($/ssf) to produce 350,000 ssf
The maintenance costs listed above depend on the unit cost per repetition of the activity
and the number of times the activity was performed. For each maintenance cost category, a BOA
was developed to characterize the cost of labor, materials, and tools associated with a single
repetition of that activity. The BOA and unit cost per repetition for each cost category are
presented in Appendix G. It was assumed that the activities and costs characterized on the BOAs
are the same regardless of the MHC process or process baths. Unit costs per repetition for both
tank cleanup and bath setup were determined to be $67.00 and $ 15.10, respectively.
4-50
-------
4.2 COST ANALYSIS
The number of tank cleanups and bath setups equals the number of bath replacements
obtained from process simulation results (see Appendix G). Each time a bath is replaced, the
tank is cleaned before a replacement bath is created. The costs of tank cleanup and bath setup are
thus given by the following:
TC = number of tank cleanups x $67.00
BS = number of bath setups x $15.10
IPC Workplace Practices Questionnaire data for both filter replacement and bath
sampling and analysis were reported in occurrences per year instead of as a function of
throughput. Ninetieth percentile values were calculated from these data and used in dermal
exposure estimates in Section 3.2, Exposure Assessment. These frequencies were adjusted for
this analysis using the URs for the production time required to manufacture 350,000 ssf of PWB.
Using the unit costs determined by the BOAs developed for filter replacement ($17.50 per
replacement) and bath sampling and testing ($3.70 per test), the costs for these maintenance
activities were calculated as follows:
FR = annual number of filter replacement xURx $17.50
ST = annual number of sampling & testing xURx $3.70
The total maintenance cost for each MHC process alternative was determined by first
calculating the individual maintenance costs using the above equations and then summing the
results.
Maintenance Costs Sample Calculations. This section presents sample maintenance
costs calculations for the non-conveyorized electroless copper process. From Table 4.23, this
process has a production time of 401 days, which gives a UR of 1.60 (UR = 401 •*• 250). The
number of tank cleanups and bath setups equals the number of bath replacements reported in
Table 4.22 (81 bath replacements). As reported in Section 3.2, Exposure Assessment, chemical
baths are sampled and tested 720 per year and filters are replaced 100 times per year. Thus, the
maintenance costs for the non-conveyorized electroless copper process are: -
TC
BS
ST
FR
therefore:
= 81 x $67.00 = $5,430
= 81 x $15.10 = $1,220
= 720xl.60x$3.70 = $4,260
= 100 x 1.60 x $17.50 = $2,800
MA = $5,430+ $1,220+ $4,260+ $2,800 - $13,700
Determination Total Cost and Unit Cost
The total cost for MHC process alternatives was calculated by summing the totals of the
individual costs categories. The unit cost (UC), or cost per ssf of PWB produced, can then be
calculated by dividing the total cost by the amount of PWBs produced. Table 4.27 summarizes
4-51
-------
4.2 COST ANALYSIS
the total cost of manufacturing 350,000 ssf of PWB using the non-conveyorized electroless
copper process.
The UC for the non-conveyorized electroless copper process was then calculated as
follows:
UC = total cost (TC) - 350,000 ssf
= $180,000 + 350,000 ssf
= $0.51/ssf
Table 4.27 Summary of Costs for the Non-Conveyorized Electroless Copper Process
Cost Category
Capital Cost
Utility Cost
Production Cost
Maintenance Cost
Total Cost
Component
Primary Equipment
Installation
Facility
Water
Electricity
Natural Gas
Transportation of Material
Labor for Line Operation
Tank Cleanup
Bath Setup
Sampling and Analysis
Component Cost
$64,000
$11,200
$8,690
$22,500
$6,540
$2,780
$0
$13,700
$737
$36,100
$5,430
$1,220
$4,260
$2,800
Totals
$83,900
$22,500
$9,320
$13,700
$36,800
$13.700
$180,000
4.2.4 Results
Table 4.28 presents the costs for each of the MHC technologies. Table 4.29 presents unit
costs ($/ssf). The total cost of producing 350,000 ssf ranged from a high of $180,000 for the
non-conveyorized electroless copper process to a low of $33,500 for the conveyorized conductive
polymer process. Corresponding unit costs ranged from $0.51/ssf for the baseline process to
$0.09/ssf for the conveyorized conductive polymer process. With the exception of the non-
conveyorized, non-formaldehyde electroless copper process, all of the alternatives cost at least 50
percent less than the baseline. Both conveyorized and non-conveyorized equipment
configurations were costed for the electroless copper, tin-palladium, and organic-palladium MHC
alternatives. For the electroless copper technology, the conveyorized process was much more
economical than the non-conveyorized process. Less difference in unit cost was seen between
the tin-palladium technologies ($0.12/ssf for conveyorized processes and $0.14/ssf for non-
conveyorized processes) and the organic-palladium technologies ($0.17/ssf for conveyorized
processes and $0.15/ssf for non-conveyorized processes). Non-conveyorized processes are, on
average, more expensive ($0.30) than conveyorized systems ($0.16).
4-52
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4.2 COST ANALYSIS
Total cost data in Table 4.28 illustrate that chemical cost is typically the largest cost (in
nine out often MHC processes) followed by equipment cost (in one out often MHC processes).
The high costs of the baseline process appear to be primarily due to the length of time it took this
process to produce 350,000 ssf(4,015 days). This is over twice as long as that required by the
next process (183 days for non-conveyorized, non-formaldehyde electroless copper).
Table 4.28 Total Cost of MHC Alternatives
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemical(s)
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Normal Production
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Electroless Copper,
non-conveyorized
$64,000
$11,200
$8,690
$22.500
$6,540
$2,780
$0
$13.700
$737
$36,1.00
$5,430
$1,220
$4,260
$2.800
$180,000
Carbon,
conveyorized
$7,470
$299
$2,690
$32.900
$725
$836
$418
$1.710
$446
$10,200
$3,280
$740
$405
$116
$62,200
Conductive
Polymer,
conveyorized
$5,560
$0
$2,250
$10.400
$410
$460
$0
$965
$673
$5,830
$4,960
$1,120
$436
$376
$33,400
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicalfe")
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Normal Production
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Electroless
Copper,,
conveyorized
$6,190
$212
$2,800
$22.600
$642
$669
$0
$1.450
$883
$7,230
$6,500
$1,460
$942
$612
$52,200
Graphite,
conveyorized
$3,580
$131
$1,090
$59,800
$251
$462
$145
$612
$319
$6,700
$2,350
$529
$316
$901
$77,200
Non-Formaldehyde
Electroless Copper^
non-conveyorized
$29,300
$5,120
$3,350
$69,600
$2,100
$1,310
$0
$4.520
$682
$16,200
$5,030
$1,130
$691
$214
$139,200
4-53
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4.2 COST ANALYSIS
Table 4.28 Total Cost of MHC Alternatives (cont.)
Cost Category
Capital Cost
Utility Cost
Production Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicals')
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Normal Production
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Organic-Palladium,
eonveyorized
$5,780
$356
$2,220
$28,900
$63 5 !
$720
$0
$1,510
$1,260
$6,530
$9,250
$2,080
$411
$271
$59,900
Organic-Palladium,
nott-eottveyorteed
$4,160
$256
$1,100
$27,000
$758
$325
$0
$1,670
$1,050
$7,190
$7,710
$1,740
$288
$385
$53,700
Cost Category
Capital Cost
Utility Cost
Production
Cost
Maintenance
Cost
Total Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicalfs)
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Normal Production
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Tin-Palladium,
conveyorized
$1,280
$205
$1,490
$25,500
$317
$468
$0
$754
$537
$5,230
$3,950
$891
$493
$332
$41,400
Tin-Palladium,
non-conveyorized
$4,760
$381
$1,910
$22,300
$1,010
$635
$0
$2,340
$455
$10,700
$3,350
$755
$916
$616
$50,100
4-54
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4.2 COST ANALYSIS
Table 4.29 MHC Alternative Unit Costs
MHC Alternative
Electroless Copper, non-conveyorized (BASELINE)
Carbon, conveyorized
Conductive Polymer, conveyorized
Electroless Copper, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, conveyorized
Organic-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Production
(ss#yr)
350,000
350,000
350,000
350,000
350,000
350,000
350,000
350,000
350,000
350,000
Total Cost
($)
$180,000
$62,200
$33,400
$52,200
$77,200
$139,200
$59,900
$53,700
$41,400
$50,100
Unit Cost
($/jssf)
$0.51
$0.18
$0.09
$0.15
$0.22
$0.40
$0.17
$0.15
$0.12
$0.14
4.2.5 Sensitivity Analysis
This section presents the results of sensitivity analyses to determine the effects of critical
variables on overall costs. Three separate sensitivity analyses were performed, including
sensitivity analyses to determine the following:
• The effects of the various cost components on the overall cost of the alternatives.
• The effects of down time on the cost of the baseline process.
• The effects of water consumption on the cost of the baseline process.
To determine the effects of the various cost components on overall cost, each cost
component was increased and decreased by 25 percent, 50 percent and 75 percent, and an overall
cost was calculated. Figure 4.15 presents the results of this sensitivity analysis for the baseline
process. Appendix G presents the results of this type of sensitivity analysis for the alternatives.
The results indicate two groupings of cost components: 1) those that have little impact on the
overall cost; and 2) those which have significant impact on the overall cost of an MHC
alternative. The first category includes tank cleanup, electricity, filter replacement, sampling and
analysis, bath setup, transportation, and natural gas costs. The second category includes
equipment, labor, and chemical costs.
To determine the effects of down time on the overall cost of the baseline process, the
duration of bath replacements was reduced by 33 percent and 67 percent. Both the 33 and 67
percent reductions led to a less than one percent reduction in overall cost. These results indicate
the effects of down time on overall costs are small.
Water consumption was also reduced by 33 percent and 67 percent to determine its
effects on the overall cost of the baseline process. Reducing water consumption affects both
water costs and wastewater discharge costs. Reducing water consumption by 33 percent resulted
in an overall cost reduction of 2.8 percent, while reducing water consumption by 67 percent
reduced the overall cost by 5.9 percent.
4-55
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4.2 COST ANALYSIS
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4-56
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4.2 COST ANALYSIS
4.2.6 Conclusions
This analysis developed comparative costs for seven MHC technologies, including
electroless copper, conductive polymer, carbon, graphite, non-formaldehyde electroless copper,
organic-palladium, and tin-palladium processes. Costs were developed for each technology and
equipment configuration for which data were available from the IPC Workplace Practices
Questionnaire and Performance Demonstration, for a total often processes (four non-
conveyorized processes and six conveyorized processes). Costs were estimated using a hybrid
cost model which combines traditional costs with simulation modeling and activity-based costs.
The cost model was designed to determine the total cost of processing a specific amount of
PWBs through a fully operational MHC line, in this case 350,000 ssf. The cost model does not
estimate start-up costs for a facility switching to an MHC alternative. Total costs were divided
by the throughput (350,000 ssf) to determine a unit cost in $/ssf.
The cost components considered include capital costs (primary equipment, installation,
and facility costs), materials costs (limited to chemical costs), utility costs (water, electricity, and
natural gas costs), wastewater costs (limited to wastewater discharge cost), production costs
(production labor and chemical transport costs), and maintenance costs (tank cleanup, bath setup,
sampling and analysis, and filter replacement costs). Other cost components may contribute
significantly to overall costs, but were not quantified because they could not be reliably
estimated. These include wastewater treatment cost, sludge recycling and disposal cost, other
solid waste disposal costs, and quality costs.
Based on the results of this analysis, all of the alternatives are more economical than the
non-conveyorized electroless copper process. In general, conveyorized processes cost less than
non-conveyorized processes. Costs ranged from $0.51/ssf for the baseline process to $0.09/ssf
for the conveyorized conductive polymer process. Seven process alternatives cost less than
$0.20/ssf (conveyorized carbon at $0.18/ssf, conveyorized conductive polymer at $0.09/ssf,
conveyorized electroless copper at $0.15/ssf, non-conveyorized organic palladium at $0.15/ssf,
conveyorized organic-palladium at $0.17/ssf, and conveyorized and non-conveyorized tin-
palladium at $0.12/ssf and $0.14/ssf, respectively). Three processes cost more than $0.20/ssf
(non-conveyorized electroless copper at $0.51/ssf, non-conveyorized non-formaldehyde
electroless copper at $0.40/ssf, and conveyorized graphite at $0.22/ssf).
Chemical cost was the single largest component cost for nine of the ten processes.
Equipment cost was the largest cost for one process. Three separate sensitivity analyses of the
results indicated that chemical cost, production labor cost, and equipment cost have the greatest
effect on the overall cost results.
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4.3 REGULATORY STATUS
4.3 REGULATORY STATUS
This section of the CTSA describes the federal environmental regulations that may affect
the chemicals in the MHC technologies. Discharges of these chemicals may be restricted by air,
water or solid waste regulations, and releases may be reportable under the federal Toxic Release
Inventory (TRI) program. This section discusses pertinent portions of the Clean Water Act
(Section 4.3.1), the Safe Drinking Water Act (Section 4.3.2), the Clean Air Act (Section 4.3.3),
the Resources Conservation and Recovery Act (Section 4.3.4), the Comprehensive
Environmental Response, Compensation and Liability Act (Section 4.3.5), the Superfund
Amendments and Reauthorization Act and Emergency Planning and Community Right-to-Know
Act (Section 4.3.6), and the Toxic Substances Control Act (Section 4.3.7). In addition, it
summarizes pertinent portions of the Occupational Safety and Health Act (Section 4.3.8).
Section 4.3.9 summarizes the federal environmental regulations by MHC technology. This
information is intended to provide an overview of environmental regulations potentially triggered
by MHC chemicals. It is not intended to be used as regulatory guidance.
The primary sources of information for this section were the EPA Register of Lists (EPA,
1996) and the EPA document, Federal Environmental Regulations Affecting the Electronics
Industry (EPA, 1995b). This is a database of federal regulations applicable to specific chemicals
that can be searched by chemical. The latter was prepared by the DfE PWB Project. Of the 62
chemicals used in one or more of the MHC technologies, no regulatory listings were found for 21
chemicals.
4.3.1 Clean Water Act
The Clean Water Act (CWA) is the basic federal law governing water pollution control in
the U.S. today. The various MHC processes used by the PWB industry contain a number of
chemicals that are regulated under the CWA. Applicable provisions, as related to specific
chemicals found in MHC technologies, are presented in Table 4.30; these particular provisions
and process-based regulations are discussed in greater detail below.
CWA Hazardous Substances and Reportahle Quantities
The CWA designates hazardous substances under Section 31 l(b)(2)(a) which, when
discharged to navigable waters or adjoining shorelines, present an imminent and substantial
danger to the public health or welfare, including fish, shellfish, wildlife, shorelines, and beaches.
40 Code of Federal Regulations (CFR) Part 117 establishes the Reportable Quantity (RQ) for
each substance listed in 40 CFR Part 116. When an amount equal to or in excess of the RQ is
discharged, the facility must provide notice to the federal government of the discharge, following
Department of Transportation requirements set forth in 33 CFR Section 153.203. Liability for
cleanup can result from such discharges. This requirement does not apply to facilities that
discharge the substance under a National Pollutant Discharge Elimination System (NPDES)
Permit or a CWA Section 404 dredge and fill permit, or to a Publicly-Owned Treatment Works
(POTW), as long as any applicable effluent limitations or pretreatment standards have been met.
Table 4.30 lists RQs of hazardous substances under the CWA that may apply to chemicals used
in the MHC process.
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4.3 REGULATORY STATUS
Table 4.30 CWA Regulations That May Apply to Chemicals in MHC Technologies
Chemical
Ammonia
Ammonium Chloride
Copper (I) Chloride; Copper
Copper Sulfate
Ethylenediaminetetraacetic Acid (EDTA)
Formaldehyde
Formic Acid
Hydrochloric Acid
Isophorone
Phosphoric Acid
Potassium Cyanide
Potassium Hydroxide
Silver
Sodium Bisulfate
Sodium Cyanide
Sodium Hydroxide
Sulfuric Acid
CWA 31 IRQ
(Ibs.)
100
5,000
10
10
5,000
100
5,000
5,000
5,000
10
1,000
5,000
10
1,000
1,000
CWA Priority
Pollutant
/
/
/
/
/
/
CWA307a
/
/
/
/
/
/
CWA304h
/
/
/
/
/
Abbreviations and definitions:
CWA - Clean Water Act
CWA 311 - Hazardous Substances
RQ - Reportable Quantities of CWA 311 hazardous substances
CWA 307a - Toxic Pollutants
CWA 304b - Effluent Limitations Guidelines
The NPDES permit program (40 CFR Part 122) contains regulations governing the
discharge of pollutants to waters of the U.S. Forty states and one territory are authorized to
administer NPDES programs that are at least as stringent as the federal program; EPA
administers the program in states that are not authorized to do so. The following discussion
covers federal NPDES requirements. Facilities may be required to comply with additional state
requirements not covered in this document.
The NPDES program requires permits for the discharge of "pollutants" from any "point
source" into "navigable waters" (except those covered by Section 404 dredge and fill permits).
CWA defines all of these terms broadly, and a source is required to obtain an NPDES permit if it
discharges almost anything other than dredge and fill material directly to surface waters. A
source that sends its wastewater to a POTW is not required to obtain an NPDES permit, but may
be required to obtain an industrial user permit from the POTW to cover its discharge.
CWA Priority Pollutants
In addition to other NPDES permit application requirements, facilities will need to be
aware of priority pollutants listed in 40 CFR Part 122, Appendix D; this list of 126 compounds
4-59
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4.3 REGULATORY STATUS
was developed by EPA to define a specific list of chemicals to be given priority consideration in
the development of effluent limitations. Each applicant for an NPDES permit must provide
quantitative data for those priority pollutants which the applicant knows or has reason to believe
will be discharged in greater than trace amounts. Each applicant must also indicate whether it
knows or has reason to believe it discharges any of the other hazardous substances or non-
conventional pollutants listed at 40 CFR Part 122, Appendix D. Quantitative testing is not
required for the other hazardous pollutants; however, the applicant must describe why it expects
the pollutant to be discharged and provide the results of any quantitative data about its discharge
for that pollutant. Quantitative testing is required for the non-conventional pollutants if the
applicant expects them to be present in its discharge.
CWA Effluent Limitations Guidelines
A principal means for attaining water quality objectives under the CWA is the
establishment and enforcement of technology-based effluent limitations, which are based on the
pollutant control capabilities of available technologies, taking into consideration the economic
achievability of these limitations and a number of other factors. Because of differences in
production processes, quantities and composition of discharges, separate standards are
established for discharges associated with different industry categories. These standards are
referred to as technology-based effluent limitation guidelines.
The effluent limitation to be applied to a particular pollutant in a particular case depends
on the following:
• Whether the pollutant is conventional, nonconventional, or toxic.
• Whether the point source is a new or existing source.
• Whether the point source discharges directly to the waters of the U.S. or to a POTW.
(Facilities that discharge to POTWs must comply with the pretreatment standards.)
Existing sources must comply with either best practicable control technology currently
available (BPT), best conventional control technology (BCT), or best available control
technology economically practicable (BAT) standards. New facilities must comply with New
Source Performance Standards. NPDES permits must also contain any more stringent permit
limitations based on state water quality standards.
In the absence of effluent limitation guidelines for a facility categoiy, permit writers
establish technology-based controls using their Best Professional Judgement. In essence, the
permit writer undertakes an effluent guideline-type analysis for a single facility. The permit
writer will use information such as permit limits from similar facilities using similar treatment
technology, performance data from actual operating facilities, and scientific literature. Best
Professional Judgement may not be used in lieu of existing effluent guidelines. These guidelines
apply only to direct dischargers of wastewater.
Pretreatment Standards
Only those facilities that discharge pollutants into waters of the U.S. need to obtain an
NPDES permit. Facilities that discharge to POTWs, however, must comply with pretreatment
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4.3 REGULATORY STATUS
requirements, as set out in Section 307 of the CWA. These requirements were developed
because of concern that discharger's waste containing toxic, hazardous, or concentrated
conventional industrial wastes might "pass through" POTWs or that pollutants might interfere
with the successful operation of the POTW.
40 CFRPart 413 contains pretreatment standards for existing sources. Existing sources
are those which, since July 15, 1983, have not commenced construction of any building or
facility that might result in a discharge. For the MHC step of the PWB manufacturing process,
the main pollutant of concern is copper and copper compounds. Table 4.31 describes PWB
pretreatment standards applicable to copper.
Table 4.31 PWB Pretreatment Standards Applicable to Copper
f S
Facilities discharging 38,000 liters or more per day -
Existing Sources
Facilities discharging 38,000 liters or more per day -
Existing Sources
All plants except job shops and independent PWB
manufacturers - Existing Sources (metal finishing)b
New Sources0 Limitations (metal finishing)
Maxinraujlorl day
(mg/l)
4.5
401a
3.38
3.38
Average Daily Value for
4 Consecutive Days
(mg/1)
2.7
24P
2.07
2.07
This category reflects>mass-based standards for rag/square foot operation, and may be applied in place of the
preceding category under prior agreement between a source subject to these standards and the POTW receiving such
regulated wastes.
b "Metal finishing" applies to plants performing any of the following operations on any basis material:
electroplating, electroless plating, anodizing, coating, chemical etching and milling and PWB manufacturing.
Pretreatment standards have been promulgated for Total Toxic Organics (TTO) in this category; none of the
chemicals evaluated in the MHC technologies are listed.
0 Pretreatment standards for new sources applies to facilities that commenced construction after July 15,1983.
4.3.2 Safe Drinking Water Act
The Federal Safe Drinking Water Act (SDWA) was first passed in 1974; it has been
amended several times. The purpose of the SDWA is to make sure the drinking water supplied
to the public is safe and wholesome. It requires water monitoring and limitations on the presence
of chemical contaminants, viruses, and other disease-causing organisms hi public water systems
that serve 25 or more people. The SDWA also includes provisions for protection of groundwater
resources in areas around wells that supply public drinking water. In addition, the injection of
wastes into deep wells that are above or below drinking water sources are regulated by the
SDWA Underground Injection Program (40 CFR Part 144). While most of the regulations under
the SWDA affect public water supplies and suppliers, PWB manufacturers could be affected by
the groundwater protection policies or the regulation of underground injection wells.
SDWA National Primary and Secondary Drinking Water Regulations
The SDWA National Primary Drinking Water Regulations (NPDWR) (40 CFR Part 141)
set maximum concentrations for substances found in drinking water that may have an adverse
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4.3 REGULATORY STATUS
affect on human health. The National Secondary Drinking Water Regulations (NSDWR)(40
CFR Part 143) established guidelines for contaminants in drinking water that primarily affect the
aesthetic qualities related to public acceptance of drinking water. The NSDWR are not federally
enforceable but are intended as guidelines for the states. Table 4.32 presents MHC chemicals
listed by these provisions of the SDWA.
Table 4.32 SWDA Regulations That May Apply to Chemicals in MHC Technologies
Chemical
Copper (I) Chloride; Copper
Copper Sulfate
Fluoroboric Acid (as fluoride)
Silver
JSWDANPDWR
/
/
/
SWDA NSDWR
/
/
/
/
Abbreviations and definitions:
SDWA - Safe Blinking Water Act
SDWA NPDWR - National Primary Drinking Water Rules
SDWA NSDWR - National Secondary Drinking Water Rules
4.3.3 Clean Air Act
The Clean Air Act (CAA), with its 1990 amendments, sets the framework for air
pollution control in the U.S. The various MHC technologies produce a number of pollutants that
are regulated under the CAA. Applicable provisions, as related to specific chemicals, are
presented in Table 4.33; these particular provisions and process-based regulations are discussed
below.
Hazardous Air Pollutants
Section 112 of the CAA established a program of regulation development for 189
hazardous air pollutants and directed EPA to add other compounds to the list as needed. EPA is
authorized to establish Maximum Achievable Control Technology (MACT) standards for source
categories that emit at least one of the pollutants on the list. Chemicals listed in Section 112(b)
of the CAA that are used in PWB manufacturing are shown in Table 4.33. EPA is in the process
of identifying categories of industrial facilities that emit substantial quantities of any of these 189
pollutants and will develop emissions limits for those industry categories.
Section 112(r) of the CAA deals with sudden releases of or accidents involving acutely
toxic, explosive, or flammable chemicals. This provision, added by the CAA Amendments of
1990, establishes a list of substances which, if present in a process in a quantity in excess of a
threshold, would require that the facility establish a Risk Management Program to prevent
chemical accidents. This program would include preparing a risk management plan for
submission to the state and to local emergency planning organizations.
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4.3 REGULATORY STATUS
Table 4.33 CAA Regulations That May Apply to Chemicals in MHC Technologies
Chemical
2-Ethoxyethanol
1,3-Benezenediol
2-Butoxyethanol Acetate; Butylcellusolve Acetate
Ammonia
Diethylene Glycol Ethyl Ether
Diethylene Glycol Methyl Ether
Dimethylformamide
Ethylene Glycol
Fluoroboric Acid (as fluoride)
Formaldehyde
Formic Acid
Hydrochloric Acid
Isophorone
Methanol
p-Tpluene Sulfom'c Acid
Potassium Cyanide
Sodium Cyanide
SulfuricAcid
CAA 111
/
/
/
/
/
/
/
/
/
/
/
/
/
/
CAA112fa
Hazardous Air Pollutants
/
/
/
/
/
/
/
/
/
/
CAA 112r
/
/
/
Abbreviations and definitions:
CAA-Clean Air Act
CAA 111 - Standards of Performance for New Stationary Sources of Air Pollutants-Equipment Leaks Chemical List
CAA 112b - Hazardous Air Pollutant
CAA 112r - Risk Management Program
Minimum Standards for State Operating Permit Programs
The CAA and its implementing regulations (at 40 CFR Part 70) define the minimum
standards and procedures required for state operating permit programs. The permit system is a
new approach established by the 1990 Amendments that is designed to define each source's
requirements and to facilitate enforcement. In addition, permit fees will generate revenue to fond
implementation of the program.
Any facility defined as a "major source" is required to secure a permit. Section 70.2 of
the regulations defines a source as a single point from which emissions are released or as an
entire industrial facility that is under the control of the same person(s). A major source is defined
as any source that emits or has the potential to emit:
• Ten tons per year (TPY) or more of any hazardous air pollutant.
• Twenty-five TPY or more of any combination of hazardous air pollutants.
• One hundred TPY of any air pollutant.
For ozone non-attainment areas, major sources are defined as sources with the potential to
emit:
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4.3 REGULATORY STATUS
• One hundred TPY or more of volatile organic compounds (VOCs) in areas defined as
marginal or moderate.
• Fifty TPY or more of VOCs in areas classified as serious.
• Twenty-five TPY or more of VOCs in areas classified as severe.
• Ten TPY or more of VOCs in areas classified as extreme.
In addition to major sources, all sources that are required to undergo New Source Review
are subject to New Source Performance Standards, or are identified by federal or state
regulations, must obtain a permit.
By November 15, 1993, each state must submit a design for an operating permit program
to EPA for approval. EPA must either approve or disapprove the state's program within one year
after submission. Once approved, the state program goes into effect.
Major sources, as well as the other sources identified above, must submit their permit
applications to the state within one year of approval of the state program. (This was scheduled to
take place near the end of 1995.) Once a source submits an application, it may continue to
operate until the permit is issued. Permit issuance may take years because permit processing
allows time for terms and conditions to be presented to and reviewed by the public and
neighboring states as well as by EPA. Applicants should make certain that their applications
contain a comprehensive declaration of all allowable emissions, because current emissions are
used as the basis for calculating proposed reductions to meet future limits.
When issued, the permit will include all air requirements applicable to the facility.
Among these are compliance schedules, emissions monitoring, emergency provisions, self-
reporting responsibilities, and emissions limitations. Five years is the maximum permit term.
As established in 40 CFR Part 70, the states are required to develop fee schedules to
ensure the collection and retention of revenues sufficient to cover permit program costs. The
CAA sets a presumptive minimum annual fee of $25 per ton for all regulated pollutants (except
carbon monoxide), but states can set higher or lower fees so long as they collect sufficient
revenues to cover program costs.
4.3.4 Resource Conservation and Recovery Act
One purpose of the Resource Conservation and Recovery Act (RCRA) of 1976 (as
amended in 1984) is to set up a cradle-to-grave system for tracking and regulating hazardous
waste. EPA has issued regulations, found in 40 CFR Parts 260-299, which implement the federal
statute. These regulations are Federal requirements. As of March 1994, 46 states have been
authorized to implement the RCRA program and may include more stringent requirements in
their authorized RCRA programs. In addition, non-RCRA-authorized states (Alaska, Hawaii,
Iowa, and Wyoming) may have state laws that set out hazardous waste management
requirements. A facility should always check with the state when analyzing which requirements
apply to their activities.
To be a hazardous waste, a material must first be a solid waste, which is defined broadly
under RCRA and RCRA regulations. Assuming the material is a solid waste, the first evaluation
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4.3 REGULATORY STATUS
to be made is whether it is also considered a hazardous waste. 40 CFR Part 261 addresses the
identification and listing of hazardous waste. The waste generator has the responsibility for
determining whether a waste is hazardous, and what classification, if any, may apply to the
waste. The generator must examine the regulations and undertake any tests necessary to
determine if the wastes generated are hazardous. Waste generators may also use their own
knowledge and familiarity with the waste to determine whether it is hazardous. Generators may
be subject to enforcement penalties for improperly determining that a waste is not hazardous.
RCRA Hazardous Waste Codes
Wastes can be classified as hazardous either because they are listed by EPA through
regulation in 40 CFR Part 261 or because they exhibit certain characteristics: toxicity,
corrosivity, reactivity, or ignitability. Listed hazardous wastes are specifically named (e.g.,
discarded commercial toluene, spent non-halogenated solvents). Characteristic hazardous wastes
are solid waste which "fail" a characteristic test, such as the RCRA test for ignitability.
There are four separate lists of hazardous wastes in 40 CFR Part 261. If any waste from a
PWB facility is on any of these lists, the facility is subject to regulation under RCRA. The listing
is often defined by industrial processes, but all wastes are listed because they contain particular
chemical constituents (these constituents are listed in Appendix VII to Part 261). Section 261.31
lists wastes from non-specific sources and includes wastes generated by industrial processes that
may occur in several different industries; the codes for such wastes always begin with the letter
"F." The second category of listed wastes (40 CFR Section 261.32) includes hazardous wastes
from specific sources; these wastes have codes that begin with the letter "K." The remaining lists
(40 CFR Section 261.33) cover commercial chemical products that have been or are intended to
be discarded; these have two letter designations, "P" and "U." Waste codes beginning with "P"
are considered acutely hazardous, while those beginning with "U" are simply considered
hazardous. Listed wastes from chemicals that are used in an MHC process are shown in Table
4.34. While this table is intended to be-as'comprehensive as possible, individual facilities may
use other chemicals and generate other listed hazardous wastes that are not included in Table
4.34. Facilities may wish to consult the lists at 40 CFR 261.31 -261.33.3
Table 4.34 RCRA Hazardous Waste Codes That May Apply to Chemical Wastes From
MHC Technologies
Chemical
2-Ethoxyethanol
1 ,3 -Benezenediol
Formaldehyde
Formic Acid
Methanol
Potassium Cyanide
Sodium Cyanide
U Waste Code
U359
U201
U122
U123
U154
P Waste Code
P098
P106
Lists of the "F, P, K and U" hazardous wastes can also be obtained by calling the EPA
RCRA/Superfund/EPCRA Hotline at (800) 424-9346.
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4.3 REGULATORY STATUS
Generator Status
The hazardous waste generator is defined as any person, by site, who creates a hazardous
waste or makes a waste subject to RCRA Subtitle C. Generators are divided into three
categories:
• Large Quantity Generators (LQG) - These facilities generate at least 1,000 kg
(approximately 2,200 Ibs) of hazardous waste per month, or greater than 1 kg (2.2 Ibs) of
acutely hazardous waste per month.
• Small Quantity Generators (SQG) - These facilities generate greater than 100 kg
(approximately 220 Ibs) but less than 1,000 kg of hazardous waste per month, and up to 1
kg (2.2 Ibs) per month of acutely hazardous waste.
Conditionally Exempt Small Quantity Generators (CESQG) - These facilities generate no
more than 100 kg (approximately 220 Ibs) per month of hazardous waste and up to 1 kg
(2.2 Ibs) per month of acutely hazardous waste.
Large and small quantity generators must meet many similar requirements. 40 CFR Part
262 provides that SQGs may accumulate up to 6,000 kg of hazardous waste on-site at any one
time for up to 180 days without being regulated as a treatment, storage, or disposal facility
(TSDF) and thereby having to apply for a TSDF permit. The provisions of 40 CFR 262.34(f)
allow SQGs to store waste on-site for 270 days without having to apply for TSDF status provided
the waste must be transported over 200 miles. LQGs have only a 90-day window to ship wastes
off-site without needing a RCRA TSDF permit. Keep in mind that most provisions of 40 CFR
Parts 264 and 265 (for hazardous waste treatment, storage and disposal facilities) do not apply to
generators who send their wastes off-site within the 90- or 180-day window, whichever is
applicable.
Hazardous waste generators that do not meet the conditions for CESQGs must (among
other requirements such as record keeping and reporting):
• Obtain a generator identification number.
• Store and ship hazardous waste in suitable containers or tanks (for storage only).
• Manifest the waste properly.
• Maintain copies of the manifest, a shipment log covering all hazardous waste shipments,
and test records.
• Comply with applicable land disposal restriction requirements.
• Report releases or threats of releases of hazardous waste.
Treatment. Storage, or Disposal Facility Status
As mentioned above, Subtitle C of RCRA (40 CFR Parts 264 and 265) outlines
regulation and permit requirements for facilities that treat, store, or dispose of hazardous wastes.
Any generator (except some CESQGs [see 40 CFR Part 261.5(g)]), no matter what monthly
waste output, who treats, stores, or disposes of waste on site is classified as a TSDF. Every
TSDF must comply with 40 CFR Part 264-267 and Part 270, including requirements to apply for
a permit and meet certain stringent technical and financial responsibility requirements.
Generators who discharge hazardous waste into a POTW or from a point source regulated by an
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4.3 REGULATORY STATUS
NPDES permit are riot required to comply with TSDF regulations, nor are generators who store
waste for short periods (see Generator Status, above).
4.3.5 Comprehensive Environmental Response, Compensation and Liability Act
The Comprehensive Environmental Response, Compensation and Liability Act (also
known as CERCLA, or more commonly as Superfund) was enacted in 1980. CERCLA is the
Act that created the Superfund hazardous substance cleanup program and set up a variety of
mechanisms to address risks to public health, welfare, and the environment caused by hazardous
substance releases.
CERCLA RQs
Substances deemed hazardous under CERCLA are listed in 40 CFR Section 302.4.
Under CERCLA, EPA has assigned a reportable quantity (RQ) to most hazardous substances;
regulatory RQs are either 1, 10, 100, 1,000, or 5,000 pounds (except for radionuclides). If EPA
has not assigned a regulatory RQ to a hazardous substance, its RQ is one pound (Section 102).
Any person in charge of a facility (or a vessel) must immediately (within a 24-hour period) notify
the National Response Center as soon as a person has knowledge of a release of an amount of a
hazardous substance that is equal to or greater than its RQ.4 There are some exceptions to this
requirement, including exceptions for certain continuous releases and for federally permitted
releases. Table 4.35 lists RQs of substances under CERCLA that may apply to chemicals used in
the MHC process.
Table 4.35 CERCLA Reportable Quantities That May Apply to Chemicals in MHC
Technologies
Chemical
1,3-Benezenediol
Ammonia
Ammonia Chloride
Copper (I) Chloride
Copper Sulfate
Dimethylformamide
Ethyl Glycol
Formaldehyde
Formic Acid
Hydrochloric Acid
CERCLA RQ
Obs)
5,000
100
5,000
10
10
100
5,000
100
5,000
5,000
Chemical
Isophorone
Methanol
Phosphoric Acid
Potassium Cyanide
Potassium Hydroxide
Silver
Sodium Cyanide
Sodium Hydroxide
Sulfuric Acid
CERCLA RQ
(Ibs)
5,000
5,000
5,000
10
1,000
1,000
10
1,000
1,000
Abbreviations and definitions:
CERCLA - Comprehensive Environmental Response,
CERCLA RQ - CERCLA reportable quantity
Compensation and Liability Act
4 The national toll-free number for the National Response Center is (800) 424-8802; in Washington, DC., call
(202) 426-2675.
4-67
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4.3 REGULATORY STATUS
CERCLA Liability
CERCLA further makes a broad class of parties liable for the costs of removal or
remediation of the release or threatened release of any hazardous substance at a facility. Section
107 specifies the parties liable for response costs, including the following: 1) current owners and
operators of the facility; 2) owners .and operators of facility at the time hazardous substances
were disposed; 3) persons who arranged for disposal or treatment, or for transportation for
disposal or treatment of such substances; and 4) persons who accepted such substances for
transportation for disposal or treatment. These parties are liable for: 1) all costs of removal or
remedial action incurred by the federal government, a state, or an Indian tribe not inconsistent
with the National Contingency Plan (NCP); 2) any other necessary costs of response incurred by
any person consistent with the NCP; 3) damages for injury to natural resources; and 4) costs of
health assessments.
4.3.6 Superfund Amendments and Reauthorization Act and
Emergency Planning and Community Right-To-Know Act
CERCLA was amended in 1986 by the Superfund Amendments and Reauthorization Act
(SARA). Title III of SARA is also known as the Emergency Planning and Community Right-To-
Know Act (EPCRA). Certain sections of SARA and EPCRA may be applicable to MHC
chemicals and PWB manufacturers. Table 4.36 lists applicable provisions as related to specific
chemicals.
Table 4.36 SARA and EPCRA Regulations That May Apply to Chemicals in MHC
Chemical
2-Ethoxyethanol
Ammonia
Copper (I) Chloride
Copper Sulfate
Dimethylformarnide
Ethylene Glycol
EDTA
Fluoroboric Acid
(as fluoride)
Formaldehyde
Formic Acid
SARA
110
/
/
/
/
/
EPCRA
3Q2a
/
/
EPCRA
313
/
/
/
/
/
/
/
/
/
Chemical
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol
Methanol
Phosphoric Acid
Potassium Cyanide
Silver
Sodium Cyanide
Stannous Chloride (as tin)
Sulfunc Acid
SARA
HO
/
/
/
EPCRA
302a
/
/
/
/
/
EPCRA
313
/
/
/
/
/
/
/
/
Abbreviations and definitions:
SARA - Superfund Amendments and Reauthorization Act
SARA 110 - Superfund Site Priority Contaminant
EPCRA - Emergency Planning & Community Right-To-Know Act
EPCRA 302a - Extremely Hazardous Substances
EPCRA 313 - Toxic Chemical Release Inventory
4-68
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4.3 REGULATORY STATES
SARA Priority Contaminants
SARA Section 110 addresses Superfiind site priority contaminants. This list contains the
275 highest ranking substances of the approximately 700 prioritized substances. These chemical
substances, found at Superfund sites, are prioritized based on their frequency of occurrence,
toxicity rating, and potential human exposure. Once a substance has been listed, the Agency for
Toxic Substances and Disease Registry (ATSDR) is mandated to develop a toxicoldgical profile
that contains general health/hazard assessments with effect levels, potential exposures, uses,
regulatory actions, and further research needs.
EPCRA Extremely Hazardous Substances
Section 302(a) of EPCRA regulates extremely hazardous substances and is intended to
facilitate emergency planning for response to sudden toxic chemical releases. These chemicals,
if present in quantities greater than their threshold planning quantities, must be reported to the
State Emergency Response Commission and Local Emergency Planning Committee and
addressed in community emergency response plans. These same substances are also subject to
regulation under EPCRA Section 304, which requires accidental releases in excess of reportable
quantities to be reported to the same state and local authorities.
EPCRA Toxic Release Inventory
Under EPCRA Section 313, a facility in SIC Codes 20-39 that has ten or more full-time
employees and that manufactures, processes, or otherwise uses more than 10,000 or 25,000
pounds per year of any toxic chemical listed in 40 CFR Section 372.65 must file a toxic chemical
release inventory (TRI) reporting form (EPA Form R) covering releases of these toxic chemicals
(including those releases specifically allowed by EPA or state permits) with the EPA and a state
agency where the facility is located. Beginning with the 1991 reporting year, such facilities must
also report pollution prevention and recycling data for TRI chemicals pursuant to Section 6607 of
the Pollution Prevention Act, 42 ;USC 13106. The threshold for reporting releases is 10,000 or
25,000 pounds, depending onliow the chemical is used (40 CFR Section 372.25). Form R is
filed annually, covers all toxic releases for the calendar year, and must be filed on or before the
first of July of the following year.
4.3.7 Toxic Substances Control Act
The Toxic Substances Control Act (TSCA)(40 CFR Part 700-799), originally passed in
1976 and subsequently amended, applies to the manufacturers, importers, processors,
distributors, users, and disposers of chemical substances or mixtures. Table 4.37 lists TSCA
regulations that may be pertinent to the MHC process.
4-69
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4.3 REGULATORY STATUS
Table 4.37 TSCA Regulations That Maj
Chemical
Benzotriazole
Diethylene Glycol Methyl Ether
Dimethylformamide
Formaldehyde
Isophorone
Isopropyl Alcohol
TSCA
Sd
HSDR
/
/
/
/
TSCA
8a
MTL
/
/
7 Apply to Chemicals in MHC Technologies
TSCA
8a
PAIR
/
/
/
/
Chemical
Palladium Chloride
Silver
Sodium Cyanide
Triethanolamine
Vanillin
TSCA
8d
HSDR
TSCA
8a
MTL
/
/
/
TSCA
8a
PAIR
/
/
/
Abbreviations and definitions:
TSCA - Toxic Substances Control Act
TSCA 8d HSDR - Health & Safely Data Reporting Rules
TSCA MTL - Master Testing List
TSCA 8a PAIR - Preliminary Assessment Information Rule
Testing Requirements
Section 4 authorizes EPA to require the testing of any chemical substance or mixture on
finding that such testing is necessary due to insufficient data from which the chemical's effects
can be predicted and that the chemical either may present an unreasonable risk of injury to health
or the environment or the chemical is produced in substantial quantities or may result in
substantial human exposure.
The TSCA Master Testing List (MTL) is a list compiled by EPA's Existing Chemicals
Program to set the Agency's testing agenda under TSCA Section 4. The major purposes are to:
1) identify chemical testing needs; 2) focus limited EPA resources on those chemicals with the
highest priority testing needs; 3) identify and publicize EPA's testing priorities for existing
chemicals; 4) obtain broad public comments on EPA's testing program and priorities; and 5)
encourage initiatives by industry to help EPA meet those priority needs. Since 1990, EPA has:
1) added 222 specific chemicals and nine categories to the MTL; 2) deleted 45 chemicals from
the MTL; 3) proposed testing for 113 chemicals via proposed rulemaking under TSCA Section 4;
4) required testing for six chemicals and one category via final TSCA Section 4 test rules,
negotiated consent orders, or voluntary testing agreements; and 5) made risk assessment or
management decisions on 41 chemicals based on TSCA Section 4 test results received. The
MTL now contains over 320 specific chemicals and nine categories.
Existing Chemical Requirements
Section 6 authorizes EPA, to the extent necessary to protect adequately against
unreasonable risk using the least burdensome requirements, to prohibit the manufacture,
processing, or distribution in commerce of a chemical substance; to limit the amounts,
concentrations, or uses of it; to require labeling or record keeping concerning it; or to prohibit or
otherwise regulate any manner or method of disposal, on finding there is a reasonable basis to
conclude that the chemical presents or will present an unreasonable risk of injury to human
health or the environment.
4-70
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4.3 REGULATORY STATUS
Preliminary Assessment Information Rules
Section 8(a) of TSCA, the Preliminary Assessment Information Rules (PAIR), establishes
procedures for chemical manufacturers and processors to report production, use, and exposure-
related information on listed chemical substances. Any person (except a "small business") who
imports, manufactures, or processes chemicals identified by EPA by rule must report information
on production volume, environmental releases, and/or chemical releases. Small businesses are
required to report such information in some circumstances.
4.3.8 Occupational Safety and Health Act
OSHA Hazard Communication Standard
The Occupational Safety and Health Administration (OSHA) governs the exposure of
workers to chemicals in the workplace. Any facility that is required by OSHA's Hazard
Communication Standard (29 CFR Section 1910.1200) to have Material Safety Data Sheets
(MSDSs) for certain hazardous chemicals, and that has such chemicals above certain minimum
threshold levels, must provide copies of the MSDSs for these substances or a list of the
substances to the State Emergency Response Commission (SERC), the Local Emergency
Planning Commission (LEPC), and the local fire department. MSDSs must also be made
available to workers. In addition, facilities must annually submit to the SERC, the LEPC, and
the fire department a Tier I report indicating the aggregate amount of chemicals (above threshold
quantities) at their facilities, classified by hazard category. If any agency that receives a Tier I
report requests a Tier II report requiring additional information, facilities must submit this second
report to the agency within 30 days of receiving a request for such a report. Tier II reports
include an inventory of all chemicals at the facility. Most of the chemicals used in the MHC
technologies industry are subject to these MSDS and Tier reporting requirements (40 CFR Part
370).
4.3.9 Summary of Regulations by MHC Technology
Tables 4.38 through 4.45 provide a summary of regulations that may apply to chemicals
in each of the MHC technology categories. Chemicals listed in bold in the tables are used in all
of the technology product lines evaluated. For example, formaldehyde is used in all of the
electroless copper lines evaluated in this study, but dimethylformamide is only used in one
product line. PWB manufacturers should check with their chemical supplier or review their
MSDSs to determine which chemicals are present in the products they use.
Chemicals and wastes from the MHC alternatives appear to be subject to fewer overall
federal environmental regulations than electroless copper. This suggests that implementing an
alternative could potentially improve competitiveness by reducing compliance costs.
4-71
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4.3 REGULATORY STATUS
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4-73
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4.3 REGULATORY STATUS
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4.3 REGULATORY STATUS
Table 4.41 Summary of Regulations That May Apply to Chemicals in the Conductive Polymer Technology
Chemicals Subjectto Applicable Regulation 1
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a Only one conductive polymer technology was evaluated. All chemicals listed were present in that product line.
4-76
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4.3 REGULATORY STATUS
Table 4.42 Summary of Regulations That May Apply to Chemicals in the Graphite Technology
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4-77
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4.3 REGULATORY STATUS
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Table 4.44 Summary of Regulations That May Apply to Chemicals in the Organic-Palladium Technology
1
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S
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palladium.
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4-80
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4.4 INTERNATIONAL INFORMATION
4.4 INTERNATIONAL INFORMATION
Several alternatives to the electroless copper process are being adopted more quickly
abroad than in the U.S. This section discusses the world market for PWBs and the international
use of MHC alternatives. It also discusses factors driving the international use of MHC
alternatives, including economic, environmental and regulatory considerations.
4.4.1 World Market for PWBs
The total world market for PWBs is approximately $21 billion (EPA, 1995c). The U.S.
and Japan are the leading suppliers of PWBs but Hong Kong, Singapore, Taiwan, and Korea are
increasing their market share. In 1994 the U.S. provided 26 percent of the PWBs in the world
market, Japan 28 percent, and Europe 18 percent (EPA, 1995c). IPC estimates that domestic
PWB imports are approximately $500 to $600 million annually (EPA, 1995c). Taiwan
comprises approximately 30 to 35 percent of the import market with Japan, Hong Kong, Korea,
and Thailand comprising 10 percent each. Domestic PWB exports were approximately $100
million in 1993, which represents two to three percent of total domestic production (EPA,
1995c).
4.4.2 International Use of MHC Alternatives
The alternatives to the traditional electroless copper MHC process are in use in many
countries abroad, including England, Italy, France, Spain, Germany, Switzerland, Sweden, Japan,
China, Hong Kong, Singapore, Taiwan, and Canada. In addition, most of the suppliers of these
alternatives have manufacturing facilities located in the-countries to which they sell. One
company provides its palladium alternative to Japan, France, Sweden, the UK, Canada, and
Germany (Harnden, 1996). Another company, which provides a palladium alternative to
electroless copper, provides both processes to England, Italy, France, Spain, Germany,
Switzerland, China, Hong Kong, Singapore, and Taiwan. Presently, that company's electroless
copper process is used more frequently than the palladium alternative (Nargi-Toth, 1996).
However, restrictions on EDTA in Germany are making the use of the palladium alternative
almost equal to the use of the traditional electroless copper process. Similarly, in Taiwan and
China the use of the palladium process is increasing relative to the electroless copper process due
to the high cost of water (Nargi-Toth, 1996). Internationally, one company reports its conductive
polymer and organic-palladium processes make up approximately five percent of the world
market (Boyle, 1996).
Another company provides its graphite alternative in Germany, England, France, Japan,
Taiwan and Hong Kong, and is opening manufacturing facilities in both China and Malaysia
within a few months (Carano, 1996). The company's graphite process is reportedly used more
frequently in Europe than is its electroless copper process. However, in Asia, the electroless
copper process is used more frequently (Carano, 1996).
Several suppliers have indicated that the use of their particular MHC alternative to
electroless copper is increasing throughout the international arena. Some suppliers have
indicated that the international usage of the electroless copper process is also on the rise but that
the MHC alternatives are increasing in usage more rapidly than traditional electroless copper
__
-------
4.4 INTERNATIONAL INFORMATION
processes (Carano, 1996). A pollution prevention and control survey performed under the DIE
PWB Project confirmed that the electroless copper is the predominate method employed in the
U.S. The survey was conducted of 400 PWB manufacturers in the U.S.; 40 responses were
received, representing approximately 17 percent of the total U.S. PWB production (EPA, 1995d).
Eighty-six percent of survey respondents use the electroless copper for most of their products, 14
percent use palladium alternatives, and one respondent uses a graphite system (EPA, 1995d).
The Pollution Prevention and Control Survey is discussed further in Chapter 1 of the CTSA.
Reasons for Use of Particular Alternatives Internationally
For the most part, the alternatives to the electroless copper process appear to be employed
due to reasons other than environmental pressures. According to international manufacturers
who participated in the Performance Demonstration Project, the most common reason for use of
an alternative is economics. According to suppliers, some of the alternatives are in fact less
costly than the traditional electroless copper process (see Section 4.2 for an analysis of the
comparative costs of alternatives developed for the CTSA). An example of this is one
company's graphite process, which reportedly costs less than the company's comparable
electroless copper process (Carano, 1996). Furthermore, several of the performance
demonstration participants in Europe indicated that their use of an alternative MHC process has
resulted in increased throughput and decreased manpower requirements.
Some of the economic drivers for adopting alternatives to the electroless copper process
internationally also relate to environmental issues. Several of the countries adopting the MHC
alternatives have high population densities as compared to the U.S., making water a scarcer
resource. As a result, these companies face high costs to buy and treat their wastewater. In
Germany, for example, companies pay one cent per gallon to have water enter the plant and then
must pay 1.2 cents per gallon to dispose of wastewater (Obermann, 1996). As a result, any
alternative that offers a reduction in the use of wastewater is potentially more attractive from a
cost-effectiveness standpoint. Several MHC alternatives allow wastewater to be reused a number
of times, something that is not available when using the electroless copper process due to the
high levels of chelators and copper that cannot be removed from the water except through
chemical treatment (Obermann, 1996). Therefore, the costs of buying the water and paying to
have it treated are reduced through the use of less water-intensive alternatives.
In some countries there are "pressures" rather than environmental regulations that have
led to the adoption of an alternative to the electroless copper MHC process. Some countries have
identified the use of EDTA and formaldehyde as areas of potential concern. For instance, in
Germany there are restrictions on the use of the chelator EDTA that are making the adoption of
non-EDTA using alternatives more attractive (Nargi-Toth, 1996). Some alternatives do not use
formaldehyde and as such are used with more frequency than the electroless copper process in
countries that are attempting to limit the use of formaldehyde (Harnden, 1996).
Barriers to Trade and Supply Information
The alternatives to the electroless copper process do not suffer from any readily apparent
barriers to trade or tariff restrictions that would make their increased adoption more costly. The
alternatives discussed above are all made from readily available materials. Therefore, if the
4-82
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4.4 INTERNATIONAL INFORMATION
demand for these alternatives should increase there should be no problem with meeting the
increased demand. Most of the suppliers of these alternatives have manufacturing facilities
located in the countries to which they sell and so they face no tariffs from importing these
chemicals. The companies that wish to use the particular alternative simply contact the
manufacturer in their country to purchase the alternatives. Therefore, there are no trade barriers
in the form of tariffs making one alternative more attractive to a potential purchaser (Carano,
1996; Nargi-Toth, 1996; Harnden, 1996). As was indicated above, most alternatives are
available in the same countries so they all appear to be on equal footing in terms of availability
and susceptibility to trade barriers.
4.4.3 Regulatory Framework
Most of the driving forces leading to the use of an alternative to electroless copper are
related to the cost-effectiveness of the alternative. However, there are several regulatory
mechanisms in place internationally that favor alternatives to traditional electroless copper
processes. These include wastewater effluent requirements and water consumption issues,
discussed below.
Wastewater Effluent Requirements
Suppliers and international performance demonstration participants report that
economics, not chemical bans or restrictions on specific chemicals, are the leading cause for the
adoption of an MHC alternative. However, wastewater effluent requirements for certain
chemicals found in electroless copper processes are also speeding the adoption of other MHC
processes. For example, in Germany the chemical EDTA is restricted so that it must be removed
from wastewater before the wastewater is discharged to an off-site wastewater treatment facility.
This restriction led one manufacturer to replace his electroless copper process with an organic-
palladium process (Schwansee, 1996). This restriction is a national one so that all companies
must adhere to it.
Also in Germany, the wastewater leaving a plant cannot contain copper in amounts in
excess of 0.5 mg/L or any ammonia (Obermann, 1996). The German regulation on copper
discharges is much more stringent than comparable regulations in the U.S., where facilities must
at least comply with federal effluent regulations and are sometimes subjected to more stringent
regulations from the states (EPA, 1995d). The federal effluent guidelines for copper discharges
are 3.38 mg/1 maximum and 2.07 mg/1 average monthly concentration (EPA, 1995d). According
to the Pollution Prevention and Control Survey discussed previously, 63 percent of the
respondents must meet discharge limitations that are more stringent than the federal effluent
limitations (EPA, 1995d). However, only 15 percent of the respondents had to meet effluent
limitations that were as stringent as, or more stringent than, the German regulation (EPA, 1995d).
Water Consumption
As indicated above, water usage is a main concern in many of the international arenas that
use these alternatives. While there are few direct regulations on the amount of water that can be
used in a MHC process, the cost of buying and treating the water make a more water-intensive
process less economical. In Germany, the high cost of purchasing water and discharging
4-83
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4.4 INTERNATIONAL INFORMATION
wastewater greatly influences the decision of whether or not to use an alternative. The less water
a process uses, the more likely it is that process will be used. In addition, in certain parts of
Germany, local authorities examine plans for the MHC process and issue permits to allow use of
the line. If the process that is proposed for use is too water-intensive, a permit will not be issued
by the local authorities (Carano, 1996). In addition, local authorities sometimes give specific
time limits in which an older more water-intensive process must be phased out (Carano, 1996).
For example, one international participant in the Performance Demonstration Project uses an
older electroless copper process for some of its products. The local authorities have given the
company four years to cease operation of the line because it uses too much water (Obermann,
1996).
4.4.4 Conclusions
The information set forth above indicates that the cost-effectiveness of an alterative has
been the main driver causing PWB manufacturers abroad to switch from an electroless copper
process to one of the newer alternatives. In addition to the increased capacity and decreased
labor requirements of some of the MHC alternatives over the non-conveyorized electroless
copper process, environmental concerns also affected the process choice. For instance, the rate at
which an alternative consumes water and the presence or absence of strictly regulated chemicals
are two factors which have a substantial affect on the cost-effectiveness of MHC alternatives
abroad. Finally, in some parts of Germany, local authorities can deny a permit for a new MHC
process line if it is deemed too water-intensive, or require an existing MHC process to be
replaced. While environmental regulations do not seem to be the primary forces leading toward
the adoption of the newer alternatives, it appears that the companies that supply these alternatives
are taking environmental regulations and concerns into consideration when designing alternatives
to the electroless copper process.
4-84
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REFERENCES
REFERENCES'
Badgett, Lona, Beth Hawke and Karen Humphrey. 1995. Analysis of Pollution Prevention and
Waste Minimization Opportunities Using Total Cost Assessment: A Study in the
Electronics Industry. Pacific Northwest Pollution Prevention Research Center
Publication, Seattle, Washington.
Boyle, Mike. 1996. Atotech, USA, Inc. 1996. Personal communication to Christine Dummer,
UT Center for Clean Products and Clean Technologies. July 19.
Carano, Mike. 1996. Electrochemicals, Inc. Personal communication to Christine Dummer,
UT Center for Clean Products and Clean Technologies. July 8.
Circuit Chemistry. 1996. Personal Communication with sales representative of Circuit
Chemistry, Golden Valley, MN (612-591-0297). June.
Coates ASI. 1996. Personal communication with sales representative of Coates ASI,
Hutchinson, MN (320-587-7555) and Phoenix, AZ (602-276-7361). June.
DeGarmo, E. Paul, William G. Sullivan and James A. Bontadelli. 1996. Engineering
Economy, 10th ed. New York, New York: Macmillan Publishing Co.
Ferguson, John H. 1996. Means Square Foot Costs: Means-Southern Construction Information
Network. Kingston, MA: R.S. Means Co., Inc. Construction. Publishers and
Consultants. •
Fisher, Helen S. 1995. American Salaries and Wages Survey, 3rd ed. Detroit, MI: Gale
Research Inc. (An International Thompson Publishing Co.)
Harnden, Eric. 1996. Solution Technological Systems. Personal communication to Christine
Dummer, UT Center for Clean Products and Clean Technologies. June 28.
KUB. 1996a; Knoxville Utilities Board. Personal communication with Jim Carmen's (Senior
VP of Gas Division) office, Knoxville, TN (423-524-2911).
KUB. 1996b. Knoxville Utilities Board. Personal communication with Bill Elmore's (VP)
office, Knoxville, TN (423-524-2911).
Microplate. 1996. Personal communication with sales representative of Microplate, Clearwater,
FL (813-577-7777). June.
Nargi-Toth, Kathy. 1996. Enthone-OMI, Inc. Personal communication to Christine Dummer,
UT Center for Clean Products and Clean Technologies. July 2.
Obermann, Alfons. 1996. MetalexGmbH. Personal communication to Christine Dummer,
UT Center for Clean Products and Clean Technologies. July 3.
4-85
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REFERENCES
PAL Inc. 1996. Personal communication with sales representative of PAL, Inc., Dallas, TX
(214-298-9898). June.
Schwansee, Gunther. 1996. Schoeller Elektronik GmbH. Personal communication to Christine
Dummer, UT Center for Clean Products and Clean Technologies. July 3.
U.S. Environmental Protection Agency (EPA). 1995a. Pollution Prevention and Control
Survey. EPA's Office of Prevention, Pesticides, and Toxic Substances, Washington, D.C.
EPA 744-R-95-006.
U. S. Environmental Protection Agency (EPA). 1995b. Federal Environmental Regulations
Affecting the Electronics Industry. EPA Office of Pollution Prevention & Toxics.
Washington, D.C. EPA744-B-95-001. September.
U.S. Environmental Protection Agency (EPA). 1995c. Printed Wiring Board Industry and Use
Cluster Profile. Design for the Environment Printed Wiring Board Project. EPA
Office of Pollution Prevention & Toxics. Washington, D.C. EPA 744-R-95-005.
September.
U.S. Environmental Protection Agency (EPA). 1995d. Printed Wiring Board Pollution
Prevention and Control: Analysis of Survey Results. Design for the Environment Printed
Wiring Board Project. EPA Office of Pollution Prevention & Toxics. Washington,
D.C. EPA 744-R-95-006. September.
U.S. Environmental Protection Agency (EPA). 1996. Register of Lists. ECLIPS Software, 13th
update (Fall, 1995). Version: Government. Washington, D.C.
Vishanoff, Richard. 1995. Marshall Valuation Service: Marshall and Swift the Building Cost
People. Los Angeles, CA: Marshall and Swift Publications.
Western Technology Associates. 1996. Personal communication with sales representative of
Western Technology Associates, Anaheim, CA (714-632-8740).
White, Allan L., Monica Becker and James Goldstein. 1992. Total Cost Assessment:
' Accelerating Industrial Pollution Prevention Through Innovative Project Financial
Analysis: With Application to Pulp and Paper Industry. EPA's Office of Pollution
Prevention and Toxics, Washington, D.C.
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Chapter 5
Conservation
Businesses are finding that by conserving natural resources and energy they can cut costs,
improve the environment, and improve their competitiveness. And due to the substantial amount
of rinse water consumed and wastewater generated by traditional electroless copper processes,
water conservation is an issue of particular concern to printed wiring board (PWB) manufacturers
and to the communities in which they are located. This chapter of the Cleaner Technologies
Substitutes Assessment (CTSA) evaluates the comparative resource consumption and energy use
of the making holes conductive (MHC) technologies. Section 5.1 presents a comparative
analysis of the resource consumption rates of MHC technologies, including the relative amounts
of rinse water consumed by the technologies and a discussion of factors affecting process and
wastewater treatment chemicals consumption. Section 5.2 presents a comparative analysis of the
energy impacts of MHC technologies, including the relative amount of energy consumed by each
MHC process, the environmental impacts of this energy consumption, and factors affecting
energy consumption during other life-cycle stages, such as chemical manufacturing or MHC
waste disposal.
5.1 RESOURCE CONSERVATION
Resource conservation is an increasingly important goal for all industry sectors,
particularly as global industrialization increases demand for limited resources. A PWB
manufacturer can conserve resources through his or her selection of an MHC process and the
manner in which it is operated. By reducing the consumption of resources, a manufacturer will
not only minimize process costs and increase process efficiency, but will also conserve resources
throughout the entire life-cycle chain. Resources typically consumed by the operation of the
MHC process include water used for rinsing panels, process chemicals used on the process line,
energy used to heat process baths and power equipment, and wastewater treatment chemicals.
The focus of this section is to perform a comparative analysis of the resource consumption rates
of the baseline and alternative MHC technologies. Section 5.1.1 discusses the types and
quantities of natural resources (other than energy) consumed during MHC operation. Section
5.1.2 presents conclusions of this analysis.
5.1.1 Natural Resource Consumption
To determine the effects that alternatives have on the rate of natural resource
consumption during the operation of the MHC process, specific data were gathered through the
Performance Demonstration Project, information from chemical suppliers, and dissemination of
the IPC Workplace Practices Questionnaire to industry. Natural resource data gathered through
these means include the following:
« Process specifications (i.e., type of process, facility size, process throughput, etc.).
« Physical process parameters and equipment description (i.e., automation level, bath size,
rinse water system configuration, pollution prevention equipment, etc.).
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5.1 RESOURCE CONSERVATION
• Operating procedures and employee practices (i.e., process cycle-time, individual bath
dwell times, bath maintenance practices, chemical disposal procedures, etc.).
• Resource consumption data (i.e., rinse water flow rates, frequency of bath replacement,
criteria for replacement, bath formulations, frequency of chemical addition, etc.).
Using the collected data, a comparative analysis of the water consumption rates for each
of the MHC alternatives was developed. For both process chemical and treatment chemical
consumption, however, statistically meaningful conclusions could not be drawn from the
compiled data. Differences in process chemicals and chemical product lines, bath maintenance
practices, and process operating procedures, just to name a few possibilities, introduced enough
uncertainty and variability to prevent the formulation of quantifiable conclusions. A qualitative
analysis of these data is therefore presented and factors affecting the chemical consumption rates
are identified. Table 5.1 summarizes the types of resources consumed during the MHC operation
and the effects of the MHC alternatives on resource conservation. Water, process chemicals, and
treatment chemicals consumption are discussed below.
Table 5.1 Effects of MHC Alternatives on Resource Consumption
Resource
Water
Process Chemicals
Energy
Treatment Chemicals
Effects of MHC Alternative on Resource Consumption
Water consumption can vary significantly according to MHC alternative and
level of automation. Other factors such as water and sewage costs and operating
practices also affect water consumption rates.
Reduction in the number of chemical baths comprising MHC substitutes typically
leads to reduced chemical consumption. The quantity of process chemicals
consumed is also dependent on other factors such as expected bath lives (e.g., the
number of surface square feet (ssf) processed before a bath must be replaced or
chemicals added), process throughput, and individual facility operating practices.
Energy consumption rates can differ substantially among the baseline and
alternatives. Energy consumption is discussed in Section 5.2.
Water consumption rates and the associated quantities of wastewater generated
as well as the elimination of chelators from the MHC process can result in
differences in the type and quantity of treatment chemicals consumed.
Water Consumption
The MHC process line consists of a series of chemical baths which are typically separated
by one, and sometimes several, water rinse steps. These water rinse steps account for virtually all
of the water consumed during the operation of the MHC process. The water baths dissolve or
displace residual chemicals from the panel surface, preventing contamination of subsequent
baths, while creating a clean panel surface for future chemical activity. The number of rinse
stages recommended by chemical suppliers for their MHC processes range from two to seven,
but can actually be much higher depending on facility operating practices. The number of rinse
stages reported by respondents to the IPC Workplace Practices Questionnaire ranged from two to
fifteen separate water rinse stages.
The flow rate required by each individual rinse tank to fulfill its role in the process is
dependent on several factors, including the time of panel submersion, the type and amount of
chemical residue to be removed, the type of agitation used in the rinse stage, and the purity of
5-2
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5.1 RESOURCE CONSERVATION
rinse water. Because proper water rinsing is critical to the MHC process, manufacturers often
use more water than is required to ensure that panels are cleaned sufficiently. Other methods,
such as flow control valves and sensors, are available to ensure that sufficient water is available
to rinse PWB panels, while minimizing the amount of water consumed by the process.
PWB manufacturers often use multiple rinse water stages between chemical process steps
to facilitate better rinsing. The first rinse stage removes the majority of residual chemicals and
contaminants, while subsequent rinse stages remove any remaining chemicals. Counter-current
or cascade rinse systems minimize water use by feeding the water effluent from the cleanest rinse
tank, usually at the end of the cascade, into the next cleanest rinse stage, and so on, until the
effluent from the most contaminated, initial rinse stage is sent for treatment or recycle. Other
water reuse or recycle techniques include ion exchange, reverse osmosis, as well as reusing rinse
water in other plant processes. A detailed description of methods to reduce water consumption,
including methods to reuse or recycle contaminated rinse water, is presented in Chapter 6 of this
CTSA.
To assess the water consumption rates of the different process alternatives, data from
chemical suppliers and the IPC Workplace Practices Questionnaire were used and compared for
consistency. Estimated water consumption rates for each alternative were provided by chemical
suppliers for each MHC process. Consumption rates were reported for three categories of
manufacturing facilities based on board surface area processed in ssf per day: small (2,000 to
6,000), medium (6,000 to 15,000), and large (15,000 +). Water consumption rates for each
alternative were also calculated using data collected from the IPC Workplace Practices
Questionnaire. An average water flow rate per rinse stage was calculated for both non-
conveyorized (1,840 gal/day per rinse stage) and conveyorized processes (1,185 gal/day per rinse
stage) from the data collected. The average flow rate was then multiplied by the number of rinse
stages in the standard configuration for each process (see Section 3.1, Source Release
Assessment) to generate a water consumption rate per day for each MHC alternative. The
number of rinse stages in a standard configuration of an alternative, the daily rinse water flow
rate calculated from the IPC Workplace Practices Questionnaire, and the daily water flow rate
reported by chemical suppliers for each MHC alternative are presented in Table 5.2.
To determine the overall amount of rinse water consumed by each alternative, the rinse
water flow rate in Table 5.2 was multiplied by the amount of time needed for each alternative to
manufacture 350,000 ssf of board (the average MHC throughput of respondents to the IPC
Workplace Practices Questionnaire). The operating time required to produce the panels was
simulated using a computer model developed for each MHC alternative. For the purposes of this
evaluation it was assumed that the water flow to the rinse stages was turned off during periods of
MHC process shutdown (e.g., bath replacements). The results of the simulation along with a
discussion of the data and parameters used to define each alternative are presented in Section 4.2,
Cost Analysis. The days of MHC operation required to manufacture 350,000 ssf from the
simulation, the total amount of rinse water consumed for each MHC alternative, and the water
consumption per ssf of board produced are presented in Table 5.3. The amount of rinse water
consumed for each alternative is also displayed in Figure 5.1.
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5.1 RESOURCE CONSERVATION
Table 5.2 Rinse Water Flow Rates for MHC Process Alternatives
MHC Process Alternative
-
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
No, of
Muse
Stages*
7
7
4
4
2
5
5
5
4
4
MHC Rinse Water Mow Rate
(gal/day)
EPC Workplace
Practices
Questionnaire11
12,880
8,300
4,740
4,740
2,370
9,200
9,200
5,930
7,360
4,740
Supplier
Data
Sheet"
5,700 - 12,500
3,840
ND
ND
1,400 - 3,800
ND
ND
ND
4,300 - 9,400
2,900 - 7,200
1 Data reflects the number of rinse stages required for the standard configuration of each MHC alternative as
reported in Section 3.1, Source Release Assessment. Multiple rinse tanks in succession were considered to be
cascaded and thus were counted as a single rinse stage with respect to water usage.
b Rinse water flow rate was calculated by averaging water flow data per stage from both questionnaire and
performance demonstrations data (non-conveyorized = 1,840 gal/day per rinse stage; conveyorized =1,185 gal/day
per rinse stage) and then multiplying by the number of rinse stages in each process.
c Data ranges reflect estimates provided by chemical suppliers for facilities with process throughputs ranging from
2,000 to 15,000 ssf per day.
ND: No Data.
An analysis of the data shows that the type of MHC process, as well as the level of
automation, have a profound effect on the amount of water that a facility will consume during
normal operation of the MHC line. All of the MHC alternatives have been demonstrated to
consume less water during operation than the traditional non-conveyorized electroless copper
process. The reduction in water usage is primarily attributable to the decreased number of rinse
stages required by many of the alternative processes and the decreased operating time required to
process a set number of boards. The table also demonstrates that the conveyorized version of a
process typically consumes less water during operation than the non-conveyorized version of the
same process, a result attributed to the decreased number of rinse steps required and the greater
efficiency of conveyorized processes. Some companies have gone a step farther by developing
equipment systems that monitor water quality and usage in order to optimize water rinse
performance, a pollution prevention technique recommended to reduce water consumption and,
thus, wastewater generation. The actual water usage experienced by manufacturers employing
such a system may be less than that calculated in Table 5.3.
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5.1 RESOURCE CONSERVATION
Table 5.3 Total Rinse Water Consumed by MHC Process Alternatives by Board
Production Rate
MHC Process Alternative
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Process
Operating
Time*
(days)
317.5
48.4
95.6
53.9
66.1
142.8
51.5
67.0
85.5
41.8
Rinse Water
Consumed
(gal/350,000 ssf>
4.09 x 106
4.02 x 105
4.53 x 105
2.55 x 105
1.57xl05
1.31 xlO6
4.74 x 105
3.97 xlO5
6.29 x 105
1.98x1 0s
Water
Consumption
Rate
(gal/ssf)
11.7
1.15
1.29
0.73
0.45
3.74
1.35
1.13
1.80
0.57
Operating time is reported in the number of days required to produce 350,000 ssf of board with a day equal to 6.8
hours of process operating time. Rinse water was assumed to be turned off during periods of process shutdown, thus
the simulated operating time for each alternative was adjusted to exclude these periods of shutdown. For a more
detailed description of the simulation model see Section 4.2, Cost Analysis.
Figure 5.1 Water Consumption Rates of MHC Alternatives
Graphite [c]
Tin-Palladium [c]
Conductive Polymer [c]
Organic-Palladium [c]
Electroless Copper [c]
Carbon [c]
Organic-Palladium [nc]
Tin-Palladium [nc]
Non-Formaldehyde Electroless Copper [nc]
Electroless Copper [nc]
4 6 8 10 12
(gal/ssf)
c: conveyorized
nc: non-conveyorized
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5.1 RESOURCE CONSERVATION
A study of direct metallization processes conducted by the City of San Jose, California
also identified reduced rinse water consumption as one of the many advantages of MHC
alternatives (City of San Jose, 1996). The study, performed by the city's Environmental Services
Department, included a literature search of currently available MHC alternatives, a survey of
PWB manufacturing facilities in the area, and a comparative analysis of the advantages of MHC
alternatives to electroless copper. The study report also presents several case studies of
companies that have already implemented MHC alternatives. The study found that 14 out of 46
(30 percent) survey respondents cited reduced water usage as a prominent advantage of replacing
their electroless copper MHC process with an alternative. On a separate survey question another
five survey respondents indicated that high water use was a prominent disadvantage of operating
an electroless copper MHC process. Although a couple of the companies studied reported little
reduction in water usage, several other companies implementing MHC alternatives indicated
decreases in water consumption. The study concluded that the magnitude of the reduction in
water consumption is site-specific depending on the facility's former process set-up and
operating practices.
Process Chemicals Consumption
Some of the resources consumed through the operation of the MHC process are the
chemicals that comprise the various chemical baths or process steps. These chemicals are
consumed through the normal operation of the MHC process line by either deposition onto the
panels or degradation caused by chemical reaction. Process chemicals are also lost through
volatilization, bath depletion, or contamination as PWBs are cycled through the MHC process.
Process chemicals are incorporated onto the panels, lost through drag-out to the following
process stages, or become contaminated through the build-up of impurities requiring the
replacement of the chemical solution. Methods for limiting unnecessary chemical loss and thus
minimizing the amount of chemicals consumed are presented in Chapter 6 in this CTSA.
Performing a comparative analysis of the process chemical consumption rates is difficult
due to the variability and site-specific nature of many of the factors that contribute to process
chemical consumption. Factors affecting the rate at which process chemicals are consumed
through the operation of the MHC process include:
• Characteristics of the process chemicals (i.e., composition, concentration, volatility, etc.).
• Process operating parameters (i.e., number of chemical baths, process throughput,
automation, etc.).
• Bath maintenance procedures (i.e., frequency of bath replacement, replacement criteria,
frequency of chemical additions, etc.).
The chemical characteristics of the process chemicals do much to determine the rate at
which chemicals are consumed in the MHC process. A chemical bath containing a highly
volatile chemical or mixture of chemicals can experience significant chemical losses to the air.
A more concentrated process bath will lose a greater amount of process chemicals in the same
volume of drag-out than a less concentrated bath. These chemical characteristics not only vary
among MHC alternatives, but can also vary considerably among MHC processes offered by
different chemical suppliers within the same MHC alternative category.
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5.1 RESOURCE CONSERVATION
The physical operating parameters of the MHC process is a primary factor affecting the
consumption rate of process chemicals. One such parameter is the number of chemical baths that
comprise the MHC process. Many of the MHC alternatives have reduced the number of
chemical process baths, not counting rinse stages, through which a panel must be processed to
perform the MHC function. The number of chemical baths in an MHC technology category
range from .eight for electroless copper to four in the graphite substitute. The process throughput,
or quantity of PWBs being passed through the MHC process, also affects chemical usage since
the higher the throughput, the more process chemicals are consumed. However, conveyorized
processes tend to consume less chemicals per ssf than non-conveyorized versions of the same
process due to the smaller bath sizes and higher efficiencies of the automated processes.
The greatest impact on process chemical consumption can result from the bath
maintenance procedures of the facility operating the process. The frequency with which baths
are replaced and the bath replacement criteria used are key chemical consumption factors.
Chemical suppliers typically recommend that chemical baths be replaced using established
testing criteria such as concentration thresholds of bath constituents (e.g., 2 g/L of copper
content). Other bath replacement criteria include ssf of PWB processed and elapsed time since
the last bath replacement. The practice of making regular adjustments to the bath chemistry
through additions of process chemicals consumes process chemicals, but extends the operating
life of the process baths. Despite the supplier recommendations, project data showed a wide
range of bath replacement practices and criteria for manufacturing facilities operating the same,
as well as different, MHC technologies.
A quantitative analysis of the consumption of process chemicals could not be performed
due to the variability of factors that affect the consumption of this resource. Chemical bath
concentration and composition differs significantly among MHC alternatives, but can also differ
considerably among chemical product lines within an MHC alternative category. Facilities
operating the same MHC alternative may have vast differences in both their MHC operating
parameters and bath maintenance procedures which can vary significantly from shop-to-shop and
from process-to-process. Because chemical consumption can be significantly affected by so
many factors not directly attributable to the type of MHC alternative (i.e., process differences
within an alternative, facility operating practices, bath maintenance procedures, etc.) it is difficult
to perform any quantitative analysis of chemical consumption among alternatives. Further
analysis of these issues is beyond the scope of this project and is left to future research efforts.
Wastewater Treatment Chemicals Consumption
The desire to eliminate chelating agents from the MHC process has been a factor in the
movement away from electroless copper processes and toward the development of substitute
MHC processes. Chelators are chemical compounds that inhibit precipitation by forming
chemical complexes with metals, allowing the metals to remain soluble in solution well past their
normal solubility limits. The elimination of chelating compounds from MHC wastewater greatly
simplifies the chemical precipitation process required to effectively treat the streams. A detailed
description of the treatment process for both chelated and non-chelated wastes, as well as a
discussion of the effect of MHC alternatives on wastewater treatment, is presented in Section 6.2,
Recycle, Recovery, and Control Technologies Assessment.
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5.1 RESOURCE CONSERVATION
The extent to which the consumption of treatment chemicals will be reduced, if any, is
dependant on several factors, some of which include the rate at which wastewater is generated
(e.g., the amount of rinse water consumed), the type of treatment chemicals used, composition of
waste streams from other plant processes, percentage of treatment plant throughput attributable to
the MHC process, the resulting reduction in MHC waste volume realized, and the extent to
which the former MHC process was optimized for waste reduction. Because many of the above
factors are site-specific and not dependent on the type of MHC process a quantitative evaluation
would not be meaningful. However, the San Jose study mentioned previously addressed this
issue qualitatively.
The San Jose study found that 21 out of 46 (46 percent) survey respondents cited ease of
waste treatment as a prominent advantage of MHC alternatives. In response to a separate
question, 8 out of 46 (17 percent) respondents cited copper-contaminated wastewater as a
prominent disadvantage of electroless copper. Most of the facilities profiled in the study reported
mixed results with regard to the effects of MHC alternatives on wastewater treatment chemical
usage. Although several companies reported a decrease in the amount of treatment chemicals
consumed, others reported no effect or a slight increase in consumption. It was concluded that
the benefits of the reduction or elimination of chelators and their impact on the consumption of
treatment chemicals is site-specific (City of San Jose, 1996).
5.1.2 Conclusions
A comparative analysis of the water consumption rates was performed for the MHC
process alternatives. The daily water flow rate was developed for the baseline and each
alternative using survey data provided by industry. A computer simulation was used to
determine the operating time required to produce 350,000 ssf of PWB for each technology and a
water consumption rate was determined. Calculated water consumption rates ranged from a low
of 0.45 gal/ssf for the graphite process to a high of 11.7 gal/ssf for the non-conveyorized
electroless copper process. The results indicate all of the alternatives consume significantly less
water than the traditional non-conveyorized electroless copper process. Conveyorized processes
were found to consume less water than non-conveyorized versions of the same process.
A quantitative analysis of both process chemicals and treatment chemicals consumption
could not be performed due to the variability of factors that affect the consumption of these
resources. The role the MHC process has in the consumption of these resources was presented
and the factors affecting the consumption rates were identified.
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5.2 ENERGY IMPACTS
5.2 ENERGY IMPACTS
Energy conservation is an important goal for PWB manufacturers, as companies strive to
cut costs and seek to improve environmental performance and global competitiveness. Energy
use has become an important consideration in the manufacture of PWBs as much of the
manufacturing process requires potentially energy-intensive operations, such as the addition of
heat to process baths. This is especially true in the operation of the MHC process, where energy
is consumed by immersion heaters, fluid pumps, air blowers, agitation devices such as vibrating
motors, and by conveyorized transport systems. The focus of this section is to perform a
comparative analysis of the relative energy consumption rates of the baseline MHC process and
process alternatives and to qualitatively assess their relative energy impacts throughout the
product life cycle.
Data collected for this analysis focus on the use of MHC chemical products in PWB
manufacturing. Although a quantitative life-cycle analysis is beyond the scope and resources of
this project, a qualitative discussion of other life-cycle stages is presented, including a discussion
of the energy impacts of manufacturing or synthesizing the chemical ingredients of MHC
products, as well as a discussion of the relative life-cycle environmental impacts resulting from
energy consumption during the use of MHC chemicals. Section 5.2.1 discusses energy
consumption during MHC process operation. Section 5.2.2 discusses the environmental impacts
of this energy consumption, while Section 5.2.3 discusses energy consumption of other life-cycle
stages. Section 5.2.4 presents conclusions of the comparative energy analysis.
5.2.1 Energy Consumption During MHC Process Operation
To determine the relative rates of energy consumption during the operation of the MHC
technologies, specific data were collected regarding energy consumption through the
Performance Demonstration project and through dissemination of the Workplace Practices
Survey to industry members. Energy data collected include the following:
• Process specifications (i.e., type of process, facility size, etc.).
• Physical process parameters (i.e., number of process baths, bath size, bath conditions such
as temperature and mixing, etc.).
* Process automation (i.e., conveyorized, computer-controlled hoist, manual, etc.).
• Equipment description (i.e., heater, pump, motor, etc.).
• Equipment energy specifications (i.e., electric load, duty, nominal power rating,
horsepower, etc.).
Each of the MHC process alternatives consist of a series of chemical baths which are
typically separated by one or more water rinse steps. In order for the process to perform
properly, each chemical bath should be operated within specific supplier recommended
parameters, such as parameters for bath temperature and mixing. Maintaining these chemical
baths within the desired parameters often requires energy-consuming equipment such as
immersion heaters, fluid circulation pumps, and air blowers. In addition, the degree of process
automation affects the relative rate of energy consumption. Clearly, conveyorized equipment
requires energy to operate the system, but also non-conveyorized systems require additional
equipment not found in conveyorized systems, such as panel agitation equipment.
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5.2 ENERGY IMPACTS
Table 5.4 lists the types of energy-consuming equipment used in MHC process lines and
the function of the equipment. In some cases, one piece of equipment may be used to perform a
function for the entire process line. For example, panel vibration is typically performed by a
single motor used to rock an apparatus that extends over all of the process tanks. The apparatus
provides agitation to each individual panel rack that is connected to it, thus requiring only a
single motor to provide agitation to every bath on the process line that may require it. In other
cases, each process bath or stage may require a separate piece of energy-consuming equipment.
Table 5.4 Energy-Consuming Equipment Used in MHC Process Lines
Type of Equipment
Conveyor Drive Motor
Immersion Heater
Fluid Pump
Air Pump
Panel Agitation Motor
Gas Heater
Ventilation Equipment
Function
Powers the conveyor system required to transport PWB panels through the
MHC process.
Raise and maintain temperature of a process bath to the optimal operating
temperature.
Circulate bath fluid to promote flow of bath chemicals through drilled
through-holes and to assist filtering of impurities from bath chemistries.
Compress and blow air into process baths to promote agitation of bath to
ensure chemical penetration into drilled through-holes. Also provides
compressed air to processes using air knife to remove residual chemicals
from PWB panels.
Agitate apparatus used to gently rock panel racks back and forth in process
baths. Not required for conveyorized processes.
Heat PWB panels to promote drying of residual moisture remaining on the
panel surface.
Provides ventilation required for MHC bath chemistries and to exhaust
chemical fumes.
To assess the energy consumption rate of each of the MHC alternatives, an energy use
profile was developed for each MHC technology that identified typical sources of energy
consumption during the operation of the MHC process. The number of MHC process stages that
result hi the consumption of energy during their operation was determined from Performance
Demonstration and Workplace Practices Survey data. This information is listed in Table 5.5
according to the function of the energy-consuming equipment. For example, a typical non-
conveyorized electroless copper process consists of four heated process baths, two baths
requiring fluid circulation, and a single process bath that is air sparged. The panel vibration is
typically performed by a single motor used to rock an apparatus that extends over all of the
process tanks. Ventilation equipment is not presented in Table 5.5 because the necessary data
were not collected during the Performance Demonstration or in the Workplace Practices Survey.
However, the amount of ventilation required varies according to the type of chemicals, bath
operating conditions, and the configuration of the process line. Because they are enclosed, the
ventilation equipment for conveyorized processes are typically more energy efficient than non-
conveyorized processes.
5-10
-------
5.2 ENERGY IMPACTS
Table 5.5 Number of MHC Process Stages that Consume Energy by Function of
Equipment
Process Type
Electroless Copper, non-conveyorized
(BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper,
non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Function of Equipment3
Conveyor
0
1
1
1
1
0
0
1
0
1
Bath
H«at
4
5
2
2
1
5
3
3
3
3
Fluid
Circulation
2
7
6
4
4
2
3
7
3
9
Air
Sparging*
1
0
0
0
0
0
0
0
1
0
Panel
Agitation*
1
0
0
0
0
1
1
0
1
0
Panel
Prying
0
0
2
0
1
0
0
0
0
0
a Table entries for each MHC alternative represent the number of process baths requiring each specific function. All
functions are supplied by electric equipment, except for drying, which is performed by gas-fired oven.
b Air sparging is used selectively by some manufacturers to enhance bath performance. Sparging may not be
required for all product lines or facilities using an alternative.
c Processes reporting panel agitation for one or more baths are entered as one in the summary regardless of the
number since a single motor can provide agitation for the entire process line.
The electrical energy consumption of MHC line equipment as well as equipment
specifications (power rating, average duty, and operating load), were collected during the
Performance Demonstration. In cases where electricity consumption data were not available, the
electricity consumption rate was calculated using the following equation and equipment
specifications:
EC = NPR x OL x AD x (lkW/0.746 HP)
where:
EC = electricity consumption rate (kWh/day)
NPR = nominal power rating (HP)
OL = operating load (%), or the percentage of the maximum load or output of
the equipment that is being used
AD = average duty (h/day), or the amount of time per day that the equipment is
being operated at the operating load
Electricity consumption data for each equipment category were averaged to determine the
average amount of electricity consumed per hour of operation for each type of equipment per
process. The natural gas consumption rate for a drying oven was supplied by an equipment
vendor. Electricity and natural gas consumption rates for MHC equipment per process stage are
presented in Table 5.6.
5-11
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5.2 ENERGY IMPACTS
Function of Equipment
Conveyorized Automation
Non-Conveyorized Process Line0
Heat
Fluid Circulation
Air Sparging
Drying Oven
Type of Equipment
Conveyor System
Panel Agitation Motor
Immersion Heater
Fluid Pump
Air Pump
Gas Heater
Energy Consumption Kates Per
Process Stage
Electricity*
(kW/hr)
14.1
3.1
4.8
0.7
3.5
-
Natural Gasfa
(frVhr)
-
-
-
-
-
90
X-rlCuU IwlLY WUllOUllllJI'AwlJL Ji wtvis JLVSJ. VI*VJ.A itj ^i** \j*. */%j **.».£»*.** wi.it, n *>«. » »*•«.— »-.«—•«- -^ — • —- —^ ^ ^j i-
per stage from the performance demonstrations. If required, consumption data were calculated from device
specifications and converted to total kW/hr per bath using 1 HP = 0.746 kW.
b Natural gas consumption rate for the gas heater was estimated by an equipment vendor (Exair Corp.).
e Non-conveyorized process lines are assumed to be manually operated with no automated panel transport system.
The electricity consumption rate reported includes the electricity consumed by a panel agitation motor.
The total electricity consumption rate for each MHC alternative was calculated by
multiplying the number of process stages that consume electricity (Table 5.5) by the appropriate
electricity consumption rate (Table 5.6) for each equipment category, then summing the results.
The calculations are described by the following equation:
n
where:
ECR,ota,
NPSi
ECRj
= total electricity consumption rate (kW/h)
= number of process stages requiring equipment i
= energy consumption rate for equipment i (kW/h)
Natural gas consumption rates were calculated using a similar method. The individual
energy consumption rates for both natural gas and electricity were then converted to British
Thermal Units (Btu) per hour and summed for each alternative to give the total energy
consumption rate for each MHC alternative. The individual consumption rates for both natural
gas and electricity, as well as the hourly energy consumption rate calculated for each of the MHC
process alternatives are listed in Table 5.7.
These energy consumption rates only consider the types of equipment listed in Table 5.4,
which are commonly recommended by chemical suppliers to successfully operate an MHC
process. However, equipment such as ultrasonics, automated chemical feed pumps, vibration
units, panel feed systems, or other types of electrically powered equipment may be part of the
MHC process line. The use of this equipment may improve the performance of the MHC line,
but is not required hi a typical process for any of the MHC technologies.
5-12
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5.2 ENERGY IMPACTS
Table 5.7 Hourly Energy Consumption Rates for MHC Alternatives
Process Type
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Energy Consumption
Rates
Electricity
(kW/hr)
27.2
43
27.2
26.5
21.7
28.5
19.6
33.4
23.1
34.8
Natural Gas
(ff/hr)
-
-
180
-
90
-
-
-
-
-
Hourly
Consumption
Rate*
(Btu/hr)
92,830
146,750
276,430
90,440
165,860
97,270
66,890
113,990
78,840
118,770
a Electrical energy was converted at the rate of 3,413 Btu per kilowatt hour where a kWh = 1 kW/hr. Natural gas
consumption was converted at the rate of 1,020 Btu per cubic feet of gas consumed.
To determine the overall amount of energy consumed by each technology, the hourly
energy consumption rate from Table 5.7 was multiplied by the amount of time needed for each
alternative to manufacture 350,000 ssf of board (the average MHC throughput of respondents to
the Workplace Practices Survey). Because insufficient survey data exist to accurately estimate
the amount of time required for each process to produce the 350,000 ssf of board, the operating
time was simulated using a computer model developed for each alternative. The results of the
simulation along with a discussion of the data and parameters used to define each alternative are
presented in Section 4.2, Cost Analysis. The hours of MHC operation required to produce
350,000 ssf of board from the simulation, the total amount of energy consumed, and the energy
consumption rate for each alternative per ssf of board produced are presented in Table 5.8.
Table 5.8 shows that all of the alternatives are more energy efficient than the traditional
non-conveyorized electroless copper process. This is primarily attributable to a process operating
time for non-conveyorized electroless copper that is two to eight times greater than the operating
times of the alternatives. Other processes with high energy consumption rates include non-
formaldehyde electroless copper due to its long operating time and both carbon and graphite due
to their high hourly consumption rates. The three processes consuming the least energy per unit
of production are the organic-palladium non-conveyorized system and the conductive polymer
and tin-palladium conveyorized systems.
The performance of specific MHC processes with respect to energy is primarily
dependent on the hourly energy consumption rate (Table 5.7) and the overall operating time for
the process (Table 5.8). Non-conveyorized processes typically have lower hourly consumption
rates than conveyorized processes because the operation of conveyorized equipment is more
energy-intensive. Although conveyorized processes typically have higher hourly consumption
rates, these differences are more than offset by the shorter operating times that are required to
produce an equivalent quantity of PWBs.
5-13
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5.2 ENERGY IMPACTS
Process Type
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Process
Operating
Time3
(hours)
2,160
329
650
367
450
971
350
456
581
284
Total
Energy
Consumed
(Btu/350?OQQ ssf)
2.01 x 108
4.83 x 107
1.80 xlO8'
3.31 xlO7
7.46 xlO7
9.44 xlO7
2.34 xlO7
5.19 xlO7
4.58 x 107
3.38 xlO7
Energy
Consumption
Elate
(Btu/ssf)
573
138
514
94.7
213
270
66.9
148
131
96.4
Times listed represent the operating time required to manufacture 350,000 ssf of board by each process as
simulated by computer model.
When MHC processes with both non-conveyorized and conveyorized versions are
compared, the conveyorized versions of the alternatives are typically more energy efficient.
Table 5.8 shows this to be true for both the electroless copper and tin-palladium processes. The
organic-palladium processes are the exceptions. The non-conveyorized configuration of this
process not only has a better hourly consumption rate than the conveyorized, but also benefits
from a faster operating time, a condition due to the low number of process baths and its short
rate-limiting step.1 These factors combine to give the non-conveyorized organic-palladium
process a lower energy consumption rate than the conveyorized version and make it the most
energy efficient process evaluated.
Finally, it should be noted that the overall energy use experienced by a facility will
depend greatly upon the operating practices and the energy conservation measures adopted by
that facility. To minimize energy use, several simple energy conservation opportunities are
available and should be implemented. These include insulating heated process baths, using
thermostats on heaters, and turning off equipment when not in use.
5.2.2 Energy Consumption Environmental Impacts
The production of energy results in the release of pollution into the environment,
including pollutants such as carbon dioxide (CO2), sulfur oxides (SOX), carbon monoxide (CO),
sulfuric acid (H2SO4), and particulate matter. The type and quantity of pollution depends on the
method of energy production. Typical energy production facilities in the U.S. include
hydroelectric, nuclear, and coal-fired generating plants.
1 The rate-limiting step is the process step that requires more time than the other steps, thus limiting the
feed rate for the system.
5-14
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5.2 ENERGY IMPACTS
The environmental impacts attributable to energy production resulting from the
differences in energy consumption among MHC alternatives were evaluated using a computer
program developed by EPA National Risk Management Research Laboratory called P2P- version
1.50214 (EPA, 1994). This program can, among other things, estimate the type and quantity of
pollutant releases resulting from the production of energy as long as the differences in energy
consumption and the source of the energy used (i.e., does the energy come from a coal-fired
generating plant, or is it thermal energy from a oil-fired boiler, etc.) are known. The program
uses data reflecting the "national average" pollution releases per kilowatt-hour derived from
particular sources. Electrical power derived from the average national power grid was selected as
the source of electrical energy, while natural gas was used as the source of thermal energy for this
evaluation. Energy consumption rates from Table 5.7 were multiplied by the operating time
required to produce 350,000 ssf of board reported for each alternative in Table 5.8. These totals
were then divided by 350,000 to get the electrical and thermal energy consumed per ssf of board,
which were then used as the basis for the analysis. Results of the environmental impact analysis
from energy production have been summarized and are presented in Table 5.9. Appendix H
contains printouts from the P2P program for each alternative.
Although the pollutant releases reported in Table 5.9 are combined for all media (i.e. air,
water, and land), they often occur in one or more media where they may present different hazards
to human health or the environment. To allow a comparison of the relative effects of any
pollution that may occur, it is necessary to identify the media of releases. Table 5.10 displays the
pollutants released during the production of energy, the media into which they are released, and
the environmental and human health concerns associated with each pollutant.
The information presented in Tables 5.9 and 5.10 show that the generation of energy is
not without environmental consequences. Pollutants released to air, water, and soil resulting
from energy generation can pose direct threats to both human health and the environment. As
such the consumption of energy by the MHC process contributes directly to the type and
magnitude of these pollutant releases. Primary pollutants released from the production of
electricity include carbon dioxide, solid wastes, sulfur oxides and nitrogen oxides. These
pollutants contribute to a wide range of environmental and human health concerns. Natural gas
consumption results primarily in releases of carbon dioxide and hydrocarbons which typically
contribute to environmental problems such as global warming and smog. Because all of the
MHC alternatives consume less energy than the traditional non-conveyorized electroless copper
process, they all decrease the quantity of pollutants released into the environment resulting from
the generation of the energy consumed during the MHC process.
5-15
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S.2 ENERGY IMPACTS
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1
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-------
5.2 ENERGY IMPACTS
Table 5.10 Pollutant Environmental and Human Health Concerns
Pollutant
Carbon Dioxide (CO2)
Carbon Monoxide (CO)
Dissolved Solids
Hydrocarbons
Nitrogen Oxides (NOJ
Participates
Solid Wastes
Sulfur Oxides (SOX)
Sulfuric Acid (H2SO4)
Medium
of Release
Air
Air
Water
Air
Air
Air
Soil
Air
Water
Environmental and Human Health Concerns
Global warming
Toxic organic/ smog
Dissolved solidsb
Odorant, smog
Toxic inorganic/ acid rain, corrosive, global warming, smog
Particulates0
Land disposal capacity
Toxic inorganic,3 acid rain, corrosive
Corrosive, dissolved solidsb
a Toxic organic and inorganic pollutants can result in adverse health effects in humans and wildlife.
b Dissolved solids are a measure of water purity and can negatively affect aquatic life as well as the future use of the
water (e.g., salinity can affect the water's effectiveness at crop irrigation).
c Particulate releases can promote respiratory illness in humans.
5.2.3 Energy Consumption in Other Life-Cycle Stages
When performing a comparative evaluation among MHC technologies, the energy
consumed throughout the entire life cycle of the chemical products in the technology should be
considered. The product use phase is only one aspect of the environmental performance of a
product. A life-cycle analysis considers all stages of the life of a product, beginning with the
extraction of raw materials from the environment, and continuing on through the manufacture,
transportation, use, recycle, and ultimate disposal of the product.
Each stage within this life cycle consumes energy. It is possible for a product to be
energy efficient during the use phase of the life cycle, yet require large amounts of energy to
manufacture or dispose of the product. The manufacture of graphite is an example of an energy-
intensive manufacturing process. Graphite is manufactured by firing carbon black particles to
temperatures over 3000 °F for several hours, which is required to give a crystalline structure to
the otherwise amorphic carbon black particles (Thorn, 1996). There are also energy consumption
differences in the transportation of wastes generated by an MHC line. The transportation of large
quantities of sludge resulting from the treatment of processes with chelated waste streams (i.e.,
electroless copper) will consume more energy than the transportation of smaller quantities of
sludge resulting from processes that do not use chelators. These examples show that energy use
from other life-cycle stages can be significant and should be considered when evaluating the
energy performance of a product. However, a comprehensive assessment of other life-cycle
stages was beyond the scope of this study.
5.2.4 Conclusions
A comparative analysis of the relative energy consumption rates was performed for the
MHC technologies. An hourly energy consumption rate was developed for the baseline and each
alternative using data collected from industry through a survey. A computer simulation was used
to determine the operating time required to produce 350,000 ssf of PWB and an energy
5-17
-------
5.2 ENERGY IMPACTS
consumption rate per ssf of PWB was calculated. The energy consumption rates ranged from
66.9 Btu/ssf for the non-conveyorized organic-palladium process to 573 Btu/ssf for the non-
conveyorized electroless copper process. The results indicate all of the MHC alternatives are
more energy efficient than the traditional non-conveyorized electroless copper process. It was
also found that for alternatives with both types of automation, the conveyorized version of the
process is typically the more energy efficient, with the notable exception of the organic-
palladium process.
An analysis of the impacts directly resulting from the production of energy consumed by
the MHC process showed that the generation of the required energy is not without environmental
consequence. Pollutants released to air, water, and soil can result in damage to both human
health and the environment. The consumption of natural gas tends to result in releases to the air
which contribute to odor, smog and global warming, while the generation of electricity can result
in pollutant releases to all media with a wide range of possible affects. Since all of the MHC
alternatives consume less energy than electroless copper, they all result in less pollutant releases
to the environment from energy production.
5-18
-------
REFERENCES
REFERENCES
City of San Jose, California. 1996. "Direct Metallization Report-Draft." Environmental
Services Dept. June.
Thorn, Ed. Electrochemicals. 1996. Personal communication with Jack Geibig, UT Center for
Clean Products and Clean Technologies. March 18.
U.S. Environmental Protection Agency. 1994. P2P-version 1.50214 computer software
program. Office of Research and Development, National Risk Management Research
Laboratory, Cincinnati, OH.
5-19
-------
REFERENCES
5-20
-------
Chapter 6
Additional Environmental Improvement Opportunities
This chapter of the Cleaner Technologies Substitute Assessment (CTSA) identifies and
qualitatively discusses techniques that can be used by printed wiring board (PWB) manufacturing
facilities to prevent pollution, minimize waste, recycle and recover valuable resources, and
control releases. The Pollution Prevention Act of 1990 set forth the following hierarchy to waste
management in order of desirability:
• Pollution prevention at the source.
• Recycling in an environmentally safe manner.
• Treatment in an environmentally safe manner.
• Disposal or other release into the environment only as a last resort and in an
environmentally safe manner.
This hierarchy has been adopted by EPA as the preferred method of waste management to
reduce or eliminate potential releases by industry. The hierarchy reflects the common sense
notion that preventing pollution is preferable to any subsequent response, be it recycling,
treatment, or disposal. By preventing pollution we also eliminate potential transfers of the
pollution across media (Kling, 1995).
The hierarchy also recognizes that pollution prevention is not always feasible and that
other waste management methods are often required. When pollution prevention is not feasible,
we should turn in order to recycling, treatment, and finally disposal if no other option remains. A
manufacturing facility often combines pollution prevention techniques with these other
approaches to effectively reduce emissions from a production process. While pollution
prevention is clearly the most desirable, all of these methods contribute to overall environmental
improvement (Kling, 1995).
This chapter focuses on the application of the waste management hierarchy to potential
waste streams generated by the making holes conductive (MHC) process of the PWB industry.
Techniques are identified, organized, and presented in an order corresponding to the hierarchy.
Pollution prevention techniques are presented in Section 6.1, while methods for minimizing
waste, recycling or recovering resources, and controlling releases are presented in Section 6.2.
While the focus of this chapter is on the MHC line, many of the techniques described here can be
applied to other processes used in PWB manufacturing. A series of pollution prevention case
studies developed by the EPA DfE Program for the PWB industry present examples of the
successful implementation of techniques available to industry (EPA, 1995a; EPA, 1995b; EPA,
1996a; EPA, 1996b; EPA, 1996c).
6-1
-------
6.1 POLLUTION PREVENTION
6.1 POLLUTION PREVENTION
Pollution prevention, defined in the Pollution Prevention Act of 1990, is the reduction in
the amounts or hazards of pollution at the source and is often referred to as source reduction.
Source reduction, also defined in the Pollution Prevention Act, is any practice which: 1) reduces
the amount of any hazardous substance, pollutant, or contaminant entering any waste stream or
otherwise released into the environment (including fugitive emissions) prior to recycling,
treatment, or disposal; and 2) reduces the hazards to public health and the environment
associated with the release of such substances, pollutants, or contaminants. Source reduction
includes equipment or technology modification, process or procedure modifications,
reformulation or redesign of products, substitution of raw materials, and improvements in
housekeeping, maintenance, training, or inventory control.
Current pollution prevention practices within the PWB industry were identified and data
were collected through contact with industry personnel, extensive review of published accounts,
and through the design and dissemination of two information requests to PWB manufacturers.
The IPC Workplace Practices Questionnaire, conducted as part of this CTSA, specifically
focused on the MHC process to identify important process parameters and operating practices for
the various MHC technologies. For a breakdown of respondents by alternative, refer to Section
1.3.4 of the Introduction. Facility characteristics of respondents are presented in Section 3.2,
Exposure Assessment. The questionnaire used in the IPC Workplace Practices Questionnaire is
presented in Appendix A.
The Pollution Prevention and Control Technology Survey (hereafter referred to as the
Pollution Prevention Survey) was designed to collect information about past and present
pollution prevention procedures and control technologies for the entire PWB manufacturing
process. This Survey was performed by the DfE PWB Project and is documented in the EPA
publication, Printed Wiring Board Pollution Prevention and Control: Analysis of Survey Results
(EPA, 1995c). The Survey results presented periodically throughout this chapter are compiled
from responses to the Pollution Prevention Survey unless otherwise indicated. Results from the
Pollution Prevention Survey pertaining to recycle or control technologies are presented in Section
6.2 of this chapter.
Opportunities for pollution prevention in PWB manufacturing were identified in each of
the following areas:
• Management and personnel practices.
• Materials management and inventory control.
• Process improvements.
The successful implementation of pollution prevention practices can lead to reductions in
waste treatment, pollution control, environmental compliance, and liability costs. Cost savings
can result directly from pollution prevention techniques that minimize water usage, chemical
consumption, and process waste generation.
6-2
-------
6.1 POLLUTION PREVENTION
6.1.1 Management and Personnel Practices
Pollution prevention is an ongoing activity that requires the efforts of both management
and employees to achieve the best results. While management's commitment to reducing
pollution is the foundation upon which a successful pollution prevention program is built, any
pollution prevention measures taken are ultimately implemented by the process employees,
making them an integral part of any pollution prevention effort. Management and employees
must work together to form an effective pollution prevention program.
Approximately half (52.6 percent) of the PWB companies responding to the Pollution
Prevention Survey reported having a formal pollution prevention policy statement while half (50
percent) of the survey respondents reported having a pollution prevention program. Over two
thirds (68.4 percent) of PWB companies surveyed reported conducting employee education for
pollution prevention.
The scope and depth of pollution prevention planning and the associated activities will
vary with the size of the facility. While larger facilities may go through an entire pollution
prevention planning exercise (as described below), smaller facilities may require as little as a
commitment by the owner to pollution prevention along with cooperation and assistance from
employees to meet any stated goals. A list of management and personnel practices that promote
pollution prevention, along with their benefits, are listed in Table 6.1.
Table 6.1 Management and Personnel
Practices Promoting Pollution Prevention
Method
Create a company pollution prevention and waste
reduction policy statement.
Develop a written pollution prevention and waste
reduction plan.
Provide periodic employee training on pollution
prevention.
Make employees accountable for their pollution
prevention performance and provide feedback on
their performance.
Promote internal communication between
management and employees.
Implement total cost accounting or activity-based
accounting system.
Benefits
Communicates to employees and states publicly the
company commitment to achieving pollution
prevention and waste reduction goals.
Communicates to employees how to accomplish the
goals identified in the company's policy statement.
Identifies in writing specific implementation steps
for pollution prevention.
Educates employees on pollution prevention
practices.
Provides incentives to employees to improve
pollution prevention performance.
Informs employees and facilitates input on pollution
prevention from all levels of the company.
Identifies true costs of waste generation and the
benefits of pollution prevention.
A company's commitment to pollution prevention begins with a pollution prevention and
waste reduction policy statement. This statement, which is the company's public proclamation of
its dedication to preventing pollution and reducing waste, should clearly state why a program is
being undertaken, include specific pollution prevention and waste reduction goals, and assign
responsibility for accomplishing those goals. The statement details to the public and to its
employees the depth of the company's commitment to pollution prevention.
6-3
-------
6.1 POLLUTION PREVENTION
A pollution prevention plan is needed to detail how the pollution prevention and waste
reduction goals described in the company's policy statement will be achieved. The pollution
prevention plan builds on the company's policy statement by:
• Creating a list of waste streams and their point sources.
• Identifying opportunities for pollution prevention.
• Evaluating and prioritizing waste reduction options.
• Developing an implementation strategy for options that are feasible.
• Creating a timetable for pollution prevention implementation.
• Detailing a plan for measuring and evaluating pollution prevention and waste reduction
progress.
The plan is best developed with input drawn from the experiences of a team of people
selected from levels throughout the company. The team approach provides a variety of
perspectives to pollution prevention and helps to identify pollution prevention opportunities and
methods for implementing them. Team members should include representatives from
management, supervisory personnel, and line workers who are familiar with the details of the
daily operation of the process. The direct participation of employees in the development of the
pollution prevention plan is important since it is the employees who are responsible for
implementing the plan.
Data should be collected by performing a waste minimization assessment on the
company or process being targeted. Once identified, pollution prevention options should be
evaluated and prioritized based on their cost, feasibility of implementation, and their overall
effectiveness of reducing waste. After an implementation strategy and timetable is established,
the plan, along with expected benefits, should be presented to the remaining company employees
to communicate the company's commitment to pollution prevention.
Once the pollution prevention plan has been finalized and implementation is ready to
begin, employees must be given the skills to implement the plan. Training programs play an
important role in educating process employees about current pollution prevention practices and
opportunities. The goal of the training program is to educate each employee on how waste is
generated, its effects on worker safety and the environment, possible methods for waste
reduction, and on the overall benefits of pollution prevention.
Employee training should begin at the time of new employee orientation, introducing
them to the company's pollution prevention plan, thus highlighting the company's dedication to
reducing waste. More advanced training focusing on process operating procedures, potential
sources of release, and pollution prevention practices already in place should be provided after a
few weeks of work or when an employee starts a new position. Retraining employees
periodically will keep them focused on the company's goal of pollution prevention.
Effective communication between management and employees is an important part of a
successful pollution prevention program. Reports to employees on the progress of implementing
pollution prevention recommendations, as well as the results of actions already taken, reiterate
management's commitment to reducing waste, while keeping employees informed and intimately
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6.1 POLLUTION PREVENTION
involved in the process. Employee input should also be solicited both during and after the
creation of the pollution prevention plan to determine if any changes in the plan are warranted.
Assigning responsibility for each source of waste is an important step in closing the
pollution prevention loop. Making individual employees and management accountable for
chemical usage and waste generated within their process or department provides incentive for
employees to reduce waste. The quantity of waste generated should be tracked and the results
reported to employees who are accountable for the process generating the waste. Progress in
pollution prevention should be an objective upon which employees will be evaluated during
performance reviews, once again emphasizing the company's commitment to waste reduction.
Employee initiative and good performance in pollution prevention areas should be
recognized and rewarded. Employee suggestions that prove feasible and cost effective should be
implemented and the employee recognized either with a company commendation or with some
kind of material award. These actions will ensure continued employee participation in the
company's pollution prevention efforts.
Implementing an activity-based or total cost accounting system will identify the costs of
waste generation that are typically hidden in overhead costs by standard accounting systems.
These cost accounting methods identify cost drivers (activities) within the manufacturing process
and assign the costs incurred through the operation of the process to the cost drivers. By
identifying the cost drivers, manufacturers can correctly assess the true cost of waste generation
and the benefits of any pollution prevention efforts.
6.1.2 Materials Management and Inventory Control
Materials management and inventory control focuses on how chemicals and materials
flow through a facility in order to identify opportunities for pollution prevention. A proper
materials management and inventory control program is a simple, cost-effective approach to
preventing pollution. Table 6.2 presents materials management and inventory control methods
that can be used to prevent pollution.
Table 6.2 Materials Management and Inventory Control Pollution Prevention Practices
Practice
Minimize the amount of chemicals kept on the floor
at one time.
Manage inventory on a first-in, first-out basis.
Centralize responsibility for storing and distributing
chemicals.
Store chemical products in closed, clearly marked
containers.
Use a pump to transfer chemical products from
stock to transportation container.
Benefits
Provides incentives to employees to use less
chemicals.
Reduces materials and disposal costs of expired
chemicals.
Provides incentives to employees to use less
chemicals.
Reduces materials loss; increases worker safety by
reducing worker exposure.
Reduces potential for accidental spills; reduces
worker exposure.
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6.1 POLLUTION PREVENTION
Controlling inventory levels and limiting access to inventory are widely used practices in
the PWB manufacturing industry (78.9 percent of Pollution Prevention Survey respondents).
Keeping track of chemical usage and limiting the amount of chemicals on the process floor
provides process operators an incentive to use the minimum quantity of chemical required to do
the job. Using chemicals on a first-in/first-out basis reduces the time chemicals spend in storage
and the amount of expired chemical that is disposed. Some companies have contracted with a
specific chemical supplier to provide all of their process chemicals and manage their inventory.
In exchange for the exclusive contract, the chemical supplier assumes many of the inventory
management duties including managing the inventory, material safety data sheets (MSDSs),
ordering the chemicals, distributing the chemicals throughout the plant, and disposing of spent
chemicals and packaging (Brooman, 1996).
Chemical storage and handling practices also provide pollution prevention opportunities.
Ensuring that all chemical containers are kept closed when not in use minimizes the amount of
chemical lost through evaporation or volatilization. When transferring chemicals from container
to container, utilizing a hand pump can reduce the amount of chemical spillage. These simple
techniques not only result in less chemical usage representing a cost savings, but also result in
reduced worker exposure and an improved worker environment.
6.1.3 Process Improvements
Improving the efficiency of a production process can significantly reduce waste
generation at the source. Process improvements include process or procedural changes in
operations carried out by employees, process equipment modification or automation, and
redesign of the process altogether. Process improvements that lead to pollution prevention in the
MHC process are categorized by the following goals:
• Extend chemical bath life.
• Reduce water consumption.
• Improve process efficiency through automation.
Pollution prevention through process improvement does not always have to be expensive.
In fact, some of the most cost-effective pollution prevention techniques are simple, inexpensive
changes in production procedures. Process improvements that help achieve the goals listed
above, along with their benefits, are discussed in detail in the sections below.
Extend Chemical Bath Life
The MHC process involves the extensive use of chemicals, many of which are costly and
pose a hazard to human health and the environment. Improvements in the efficient usage of
these chemicals can occur by accomplishing the following:
• Reducing chemical bath contamination.
• Reducing chemical bath drag-out.
• Improving bath maintenance.
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6.1 POLLUTION PREVENTION
Inefficiencies in the use of chemicals can result in increased chemical usage, higher
operating costs, increased releases to the environment, and increased worker exposure.
Techniques to improve the efficient use of chemicals by the MHC and other PWB process steps
are discussed in detail below.
Reduce Bath Contaminants. The introduction of contaminants to a chemical bath will
affect its performance and significantly shorten the life of the chemical bath. Bath contaminants
include chemicals dragged-in from previous chemical baths, chemical reaction by-products, and
particulate matter which may be introduced to the bath from the air. Process baths are replaced
when impurities reach a level where they degrade product quality to an unacceptable level. Any
measure that prevents the introduction of impurities will not only result in better bath
performance, but also will reduce chemical usage and generate less waste. Table 6.3 presents
pollution prevention methods for reducing bath contamination.
Table 6.3 Pollution Prevention Practices to Reduce Bath Contaminants
Practices
Improve the efficiency of the water rinse system.
Use distilled or deionized water during chemical
bath make-up.
Maintain and rebuild panel racks.
Clean process tanks efficiently before new bath
make-up.
Utilize chemical bath covers when process baths
are not in operation.
Filter contaminants continuously from process
baths.
Benefits
Rinses off any residual bath chemistries and
dislodges any particulate matter from panels and
racks.
Reduces chemical contamination resulting from
water impurities.
Prevents the build-up of deposits and corrosion
that can dislodge or dissolve into chemical baths.
Prevents contamination of the new bath from
residual spent bath chemistries.
Reduces the introduction of unwanted airborne
particulate matter; prevents evaporation or
volatilization of bath chemistries.
Prevents the build-up of any contaminants.
Thorough and efficient water rinsing of process panels and the racks that carry them is
crucial to preventing harmful chemical drag-in and to prolonging the life span of the chemical
baths. The results of the IPC Workplace Practices Questionnaire indicate that nearly every
chemical bath in the MHC process is preceded by at least one water rinse tank. Improved rinsing
can be achieved by using spray rinses, panel and/or water agitation, warm water, or by several
other methods that do not require the use of a greater volume of water. A more detailed
discussion of these methods is presented in the reduced water consumption portion in this
section.
A rack maintenance program is also an important part of reducing chemical bath
contamination and is practiced by 87 percent of the respondents to the Pollution Prevention
Survey. By cleaning panel racks regularly and replacing corroded metal parts, preferably with
parts of plastic or stainless steel, chemical deposition and build-up can be minimized.
Respondents to the IPC Workplace Practices Questionnaire typically perform rack cleaning using
a chemical solution, usually acid. Mechanical methods, such as peeling or filing away the
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6.1 POLLUTION PREVENTION
majority of any metal deposits before applying a weak acid solution, can be used to prevent
pollution by reducing the quantity of acid required. An added benefit is that the reclaimed metal
can be sold or reused in the process.
According to the IPC Workplace Practices Questionnaire, 42 percent of the respondents
reported using bath covers on at least some of their baths during periods when the MHC process
was not operating. Respondents were not specifically questioned about the other methods for
reducing bath contamination described above; consequently, no information was collected.
Chemical Bath Drag-Out Reduction. The primary loss of bath chemicals during the
operation of the MHC process comes from chemical bath drag-out (Bayes, 1996). This loss
occurs as the rack full of panels is being removed from the bath, dragging with it a film of
chemical solution still coating the panels. The drag-out is then typically rinsed from the panels
by a water rinse tank, making bath drag-out the primary source of chemical contaminant
introduction into the MHC rinse water. In some cases, however, the panels are deposited directly
into the next process bath without first being rinsed (e.g., predip followed directly by palladium
catalyst in tin-palladium process).
Techniques that minimize bath drag-out also prevent the premature reduction of bath
chemical concentration, extending the useful life of a bath. In addition to extended bath life,
minimizkig or recovering drag-out losses also has the following effects:
• Requires less rinse water.
• Minimizes bath chemical usage.
• Reduces chemical waste.
• Requires less water treatment chemical usage.
Methods for reducing or recovering chemical bath drag-out are presented in Table 6.4 and
then discussed below.
The most common methods of drag-out control employed by respondents to the Pollution
Prevention Survey are slow panel removal from the bath (52.6 percent) and increased panel
drainage time (76.3 percent). Removing the panels slowly from the bath allows the surface
tension of the solution to remove much of the residual chemical from the panels. Most of the
remaining chemicals can be removed from the panel surfaces by increasing the time allowed for
the panels to drain over the process bath. Briefly agitating the panels directly after being
removed from the tank can also help dislodge chemicals trapped in panel through-holes and
result in better drainage. All three methods require no capital investment and when practiced
individually or in combination, these techniques are effective methods for reducing drag-out.
Drain boards catch drag-out chemicals that drip from panels as they are transported to the
next process step. The chemicals are then returned to the original process bath. Chemical loss
due to splashing can be prevented by the use of drip shields, which are plastic panels that extend
the wall height of the process tank. Both drain boards and drip shields are inexpensive, effective
drag-out control options. Unlike drip shields, however, space between process steps is required
to install drain boards, making them impractical where process space is an issue.
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6.1 POLLUTION PREVENTION
Methods
Remove panels slowly from process baths.
Increase panel drainage time over process bath.
Agitate panels briefly while draining.
Install drain boards.
Install drip shields between process baths.
Add static drag-out tanks/drip tanks to process line
where needed.
Utilize non-ionic wetting agents in the process bath
chemistries.
Utilize air knives directly after process bath in
conveyorized system.3
Decrease process bath viscosity.
Employ fog rinses/spray rinses over heated baths.
Benefits
Reduces the quantity of residual chemical on panel
surfaces.
Allows a greater volume of residual bath
chemistries to drip from the panel back into the
process bath.
Dislodges trapped bath chemistries from drilled
through-holes.
Collects and returns drag-out to process baths.
Prevents bath chemical loss due to splashing.
Recovers chemical drag-out for use in bath
replenishment.
Reduces surface tension of bath solutions, thereby
reducing residual chemicals on panel surfaces.
Blows residual process chemistries from process
panels which are recaptured and returned to
process bath.
Reduces quantity of chemical that adheres to panel
surface.
Rinses drag-out from the panels as they are
removed from the solution.
May not be a viable pollution prevention technique unless system is fully enclosed to prevent worker exposure to
bath chemicals introduced to the air.
Much of the chemical solution lost to drag-out can be recovered through the use of either
static drag-out tanks or drip tanks. A static drag-out tank is a batch water bath that immediately
follows the process bath from which the drag-out occurs. The panels are submerged and agitated
in the static rinse water, washing the residual chemicals from the panel's surface. When
sufficiently concentrated, the rinse water and chemical mixture can be used to replenish the
original bath. Drip tanks are similar to static drag-out tanks except that they contain no water.
The drip tank collects chemical drag-out which can then be returned to the process bath. Static
drag-out tanks are most suitably used in conjunction with heated process baths which lose water
by evaporation, requiring frequent replacement.
Bath viscosity can be lowered by increasing bath temperature, decreasing bath
concentration, or both. Both of these methods may negatively affect overall process performance
if done in excess, however, and the chemical supplier should be consulted. In addition, increased
bath temperatures can increase chemical volatilization and worker exposure. Energy
implications of higher temperature baths should also be considered and are discussed in Section
5.2.
Bath Maintenance Improvements. The MHC process and other wet chemistry
processes in PWB manufacturing are series of complex, carefully balanced and formulated
chemical mixtures, each one designed to operate at specific conditions, working together to
perform an overall function. A bath testing and control program is essential in preventing the
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6.1 POLLUTION PREVENTION
chemical breakdown of process baths, thus extending their useful lives and preventing their
premature disposal. The premature disposal of process chemistries results in increased chemical
costs for both bath and treatment chemicals, prolonged process down-time, and increased process
waste.
Bath maintenance, or control, refers to maintaining a process bath in peak operating
condition by identifying and controlling key operating parameters, such as bath temperature,
individual chemical concentrations, pH, and the concentration of contaminants. Proper control
of bath operating parameters will result in more consistent bath operation, less water usage, and
better, more consistent quality of work.
According to Pollution Prevention Survey respondents, the majority of PWB
manufacturing facilities (92.1 percent) have a preventative bath maintenance program already in
place. Typical bath maintenance methods and their benefits are presented in Table 6.5 below.
Table 6.5 Bath Maintenance Improvement Methods To Extend Bath Life
Methods
Monitor bath chemistries by testing frequently.
Replace process baths according to chemical
testing.
Maintain operating chemical balance through
chemical additions according to testing.
Filter process baths continuously.
Employ steady state technologies.
Install automated/statistical process control system.
Utilize temperature control devices.
Utilize bath covers.
Benefits
Determines if process bath is operating within
recommended parameters.
Prevents premature chemical bath replacement of
good process baths.
Maintains recommended chemical concentrations
through periodic chemical replenishment as
required.
Prevents the build-up of harmful impurities that
may shorten bath life.
Maintains steady state operating conditions by
filtering precipitates or regenerating bath solutions
continuously.
Provides detailed analytical data of process
operating parameters, facilitating more efficient
process operation.
Regulates bath temperatures to maintain optimum
operating conditions.
Reduces process bath losses to evaporation and
volatilization.
Frequent monitoring and adjustment of the various chemical concentrations within a
process bath are the foundations on which a good bath maintenance program is built. Monitoring
is done by regularly testing the bath concentrations of key chemicals to ensure that the bath is
chemically balanced. If chemical concentrations are outside of the operating levels
recommended by the supplier, a volume of chemical is added to the bath to bring it back into
balance. When the concentration of contaminants reaches an established critical level, or some
other criteria reported by the supplier, the bath is disposed of and replaced with a new bath.
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6.1 POLLUTION PREVENTION
Bath testing and adjustment can be performed manually or with an automated system that
can perform both functions. Either way, controlling the bath through regular testing and bath
additions is an inexpensive, effective method for extending bath life and reducing pollution.
Nearly all of the PWB facilities surveyed (97.4 percent) report testing chemical bath
concentrations.
Bath replacement should be based upon chemical testing, instead of some other
predetermined criteria. Predetermined criteria, such as times or production volumes, are often
given by suppliers as safe guidelines for bath replacement for facilities that do not regularly test
their process baths. These criteria are conservative estimates of the effective life of the process
bath, but can be exceeded with a proper bath testing and maintenance program. By replacing the
process bath only when chemical testing indicates it is required, bath life can be extended while
chemical usage and waste are reduced. Most (92.1 percent) of the surveyed PWB facilities
reported replacing their process baths only when testing indicated.
The build-up of contaminants in a process bath will eventually require the bath to be
replaced. Bath contaminants can be solid matter, such as particulate matter and precipitates, or
undesired chemical species in solution, such as reaction byproducts or drag-in chemicals. An
effective method of extending bath life is to continuously filter the process bath to remove
undesired bath constituents. Installing standard cartridge or bag filters which remove solid
impurities from the bath is another inexpensive, yet effective method to extend bath life.
Some baths may be maintained at steady state conditions using readily obtainable systems
capable of regenerating or filtering process bath chemistries. For example, a system that
continuously filters the copper sulfate precipitate from peroxide-sulfuric microetch baths can be
used to maintain the microetch bath on a MHC process line, providing a recyclable precipitate.
Regeneration techniques can be used to continuously regenerate both alkaline and cupric chloride
etchants. Maintaining steady state conditions keeps a bath within the optimal operating
conditions resulting in extended bath life (Edwards, 1996).
Statistical process control (SPC) is a method of analyzing the current and past
performance of a process bath, using chemical testing results and operating condition records to
optimize future bath performance. SPC will lead to more efficient bath operation and extended
bath life by indicating when a bath needs maintenance through the tracking and analysis of
individual operating parameters and their effect on past performance (Fehrer, 1996). Only one
quarter (26.3 percent) of the survey respondents reported using a SPC system.
Many of the MHC process baths are heated, making temperature control an important
necessity for proper bath operation. If bath temperature is not controlled properly, the bath may
not be hot enough to perform its function, or may become too hot, leading to chemical and water
losses due to evaporation or volatilization. The bath chemicals that remain become more
concentrated, resulting in increased chemical loss to drag-out. By installing thermostats on all
heated process baths, solution temperature will be kept constant, reducing waste generation and
chemical and energy use, and saving money through decreased energy use, chemical use, and
waste treatment costs.
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6.1 POLLUTION PREVENTION
Another method of limiting evaporative losses from process baths is to cover the surface
of the solution with floating plastic balls that will not react with the process solution. The plastic
balls, which do not interfere with the work pieces being processed, prevent the evaporation of the
bath solution by limiting the surface area of solution exposed to the air. One facility uses ping
pong balls which are made from polystyrene to minimize losses from the electroless copper bath.
Hexagonal-shaped balls are now available that leave even less surface area exposed to the air
(Brooman, 1996). This method is especially effective for higher temperature process baths where
evaporative losses tend to be high. This method is inexpensive, easy to utilize, and will decrease
the air emissions from the bath, limiting the amount of operator exposure to the chemicals.
Reduced Water Consumption
Contaminated rinse water is the primary source of heavy metal ions discharged to waste
treatment processes from the MHC process and other wet chemistry process lines (Bayes, 1996).
These contaminants, which are introduced to the rinse water through chemical drag-out, must be
treated and removed from the water before it can be reused in the process or discharged to the
sewer. Because rinsing is often an uncontrolled portion of the process, large quantities of water
are consumed and treated unnecessarily. Reducing the amount of water used by the MHC
process has the following benefits:
• Decreases water and sewage costs.
• Reduces wastewater treatment requirements, resulting in less treatment chemical usage
and reduced operating costs.
• Reduces the volume of sludge generated from wastewater treatment.
• Improves opportunities to recover process chemicals from more concentrated waste
streams.
The MHC process line consists of a series of chemical baths, which are typically
separated by at least-one, and sometimes more, water rinse steps. These water rinse steps
account for virtually all of the water used during the operation of the MHC line. The water baths
act as a buffer, dissolving or displacing any residual drag-in chemicals from the panels surface.
The rinse baths prevent contamination of subsequent baths while creating a clean surface for
future chemical activity.
Improper rinsing does not only lead to shortened bath life through increased drag-in, as
discussed previously, but can also lead to a host of problems affecting product quality, such as
peeling, blistering and staining. Insufficient rinsing of panels can lead to increased chemical
drag-in'quanthi68 and will fail to provide a clean panel surface for subsequent chemical activity.
Excessive water rinsing, done by exposing the panels too long to water rinsing, can lead to
oxidation of the copper surface and may result in peeling, blistering, and staining. To avoid
insufficient rinsing, manufacturers often use greater water flow rates than are necessary, instead
of using more efficient rinsing methods that reduce water consumption but may be more
expensive to implement. These practices were found to be true among survey respondents,
where facilities with low water and sewage costs typically used much larger amounts of water
than comparable facilities with high water and sewer costs.
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6.1 POLLUTION PREVENTION
Many techniques are available that can reduce the amount of water consumed while
rinsing. These techniques are categorized by the following:
• Methods to control water flow.
• Techniques to improve water rinse efficiency.
• Good housekeeping practices.
Flow control methods focus on controlling the flow of water, either by limiting the
maximum rate that water is allowed to flow into the rinse system, or by stopping and starting the
water flow as it is needed. These methods seek to limit the total water usage while ensuring that
sufficient water is made available to cleanse the PWB panels. Examples of these techniques
include the use of flow restrictors or smaller diameter piping to limit the maximum flow of
water, and control valves that provide water to the rinse baths only when it is needed. Control
valves can be either manually operated by an employee, or automated using some kind of sensing
device such as conductivity meters, pH meters, or parts sensors. All of the methods are effective
water reduction techniques that can be easily installed.
Pollution prevention techniques directed at improving water efficiency in the rinse system
seek to control or influence the physical interaction between the water and the panels. This can
be done by increasing bath turbulence, improving water quality, or by using a more efficient rinse
configuration. All of these methods, discussed below, seek to improve rinsing performance
while using less water.
Increasing bath turbulence can be accomplished through the use of ultrasonics, panel
agitation, or air sparging. All of these agitation methods create turbulence in the bath, increasing
contact between the water and the part, thereby accelerating the rate that residual chemicals are
removed from the surface. Agitating the bath also keeps the water volume well mixed,
distributing contaminants throughout the bath and preventing concentrations of contaminants
from becoming trapped. However, agitating the bath can also increase air emissions from the
bath unless pollution prevention measures are used to reduce air losses.
Water quality can be improved by using distilled or deionized water for rinsing instead of
tap water that may include impurities such as carbonate and phosphate precipitates, calcium,
fluoride, and iron. Finally, utilizing more efficient rinse configurations such as countercurrent
rinse stages, spray rinses, or fog rinses will increase the overall efficiency of the MHC rinse
system while reducing the volume of wastewater generated. PWB manufacturers often use
multiple rinse water stages between chemical process steps to facilitate better rinsing. The first
rinse stage removes the majority of residual chemicals and contaminants, while subsequent rinse
stages remove any remaining chemicals. Counter-current or cascade rinse systems minimize
water use by feeding the water effluent from the cleanest rinse tank, usually at the end of the
cascade, into the next cleanest rinse stage, and so on, until the effluent from the most
contaminated, initial rinse stage is sent for treatment or recycle.
Good housekeeping practices focus on keeping the process equipment in good repair and
fixing or replacing leaky pipes, pumps, and hoses. These practices can also include installing
devices such as spring loaded hose nozzles that shut off when not in use, or water control timers
that shut off water flow in case of employee error. These practices often require little investment
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6.1 POLLUTION PREVENTION
and are effective in preventing unnecessary water usage. For a more detailed discussion on
methods of improving water rinse efficiency and reducing water consumption, refer to Section
5.1, Resource Conservation.
Improve Process Efficiency Through Automation
The operation of the MHC process presents several opportunities for important and
integral portions of the process to become automated. By automating important functions,
operator inconsistencies can be eliminated allowing the process to be operated more efficiently.
Automation can lead to the prevention of pollution by:
Gaining a greater control of process operating parameters.
Performing the automated function more consistently and efficiently.
Eliminating operator errors.
Making the process compatible with newer and cleaner processes designed to be operated
with an automated system.
Automating a part of the MHC process can be expensive. The purchase of some
automated equipment can require a significant initial investment, which may prevent small
companies from automating. Other costs that may be incurred include installing the equipment,
training employees, any lost production due to process down-time, and the cost of redesigning
other processes to be compatible with the new system. Although it may be expensive, the
benefits of automation on productivity and waste reduction will result in a more efficient process
that can save money over the long run.
Installation of automated equipment such as a rack or panel transportation system,
chemical sampling equipment, or an automated system to make chemical additions can have a
major impact on the quantity of pollution generated during the day-to-day operation of the MHC
process and can also reduce worker exposure. MHC process steps or functions that can be
automated effectively include:
• Rack transportation.
• Bath maintenance.
• Water flow control.
Rack transportation systems present an excellent opportunity for automation, due to the
repetitive nature of transporting panel racks. Various levels of automation are available ranging
from a manually operated vertical hoist to a computer controlled robotic arm. All of these
methods allow for greater process control over panel movement through the MHC process line.
By building in drag-out reduction methods such as slower panel withdraw and extended drainage
times into the panel movement system, bath chemical loss and water contamination can be
greatly reduced.
Automating bath maintenance testing and chemical additions can result in longer bath life
and reduced waste. These systems monitor bath solutions by regularly testing bath chemistries
for key contaminants and concentrations. The system then adjusts the process bath by making
small chemical additions, as needed, to keep contaminant build-up to a minimum and the process
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6.1 POLLUTION PREVENTION
bath operating as directed. The resulting process bath operates more efficiently, resulting in
prolonged bath life, less chemical waste, reduced chemical cost, and reduced drag-out.
Controlling rinse water flow is an inexpensive process function to automate. Techniques
for controlling rinse water flow were discussed previously. The reduction in fresh water usage as
a result of automating these techniques will not only reduce water costs, but will also result in
reduced treatment chemical usage and less sludge.
A conveyorized system integrates many of the methods described above into a complete
automated MHC system. The system utilizes a series of process stages connected by a horizontal
conveyor to transport the PWB panels through the MHC process. Drag-out is greatly reduced
due, in part, to the separate process stages, and to the vertical alignment of the drilled holes that
trap less chemicals. Since drag-out is reduced, much less rinse water is required to cleanse the
panel surfaces, resulting in reduced water and treatment costs. A single water tank is sufficient
between process baths where multiple stages may be required in a non-conveyorized process,
thus dramatically reducing the number of process stages required, resulting in a much shorter
cycle time and reduced floor space requirements. The enclosed process stages limit evaporative
losses, reducing chemical costs, while also reducing the amount of chemical to which an
employee is exposed. Several MHC alternative chemistry processes have been designed to
operate effectively using this type of conveyorized system.
A conveyorized system should also take advantage of other pollution prevention
techniques., such as water flow controllers, bath maintenance techniques and other methods
discussed throughout this module, to further reduce waste. By integrating all of these methods
together into a single MHC system, the process operates more efficiently, reducing water and
chemical consumption, resulting in less process waste and employee exposure.
Segregate Wastewater Streams to Reduce Sludge Generation. Another type of
process improvement to prevent pollution relates to segregating the wastewater streams
generated by MHC and other PWB manufacturers process steps. The segregation of wastewater
streams is a simple and cost-effective pollution prevention technique for the MHC process. In a
typical PWB facility, wastewater streams from different process steps are often combined and
then treated by an on-site wastewater treatment process to comply with local discharge limits.
Some waste streams from the MHC process, however, may contain chelating agents.
These chelators, which permit metal ions to remain dissolved in solution at high pH levels, must
first be broken down chemically before the waste stream can be treated and the heavy metal ions
removed. Treatment of waste containing chelators requires extra treatment steps or more active
chemicals to break down the chelating agents and precipitate out the heavy metal ions from the
remaining water effluent. Because the chelator-bearing streams are combined with other non-
chelated streams before being treated, a larger volume of waste must be treated for chelators than
is necessary, which also results in a larger volume of sludge.
To minimize the amount of treatment chemical used and sludge produced, the chelated
waste streams should be segregated from the other non-chelated wastes and collected in a storage
tank. When enough waste has been collected, the chelated wastes should be batch treated to
breakdown the chelator and remove the heavy metals. The non-chelated waste streams can then
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6.1 POLLUTION PREVENTION
be treated by the on-site wastewater treatment facility without additional consideration. By
segregating and batch treating the chelated heavy metal wastes from other non-hazardous waste
streams, the volume of waste undergoing additional treatment is minimized and treatment
chemical usage and sludge generation reduced.
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
While pollution prevention is the preferred method of waste management, the waste
management hierarchy recognizes that pollution prevention is not always feasible. Companies
often supplement their pollution prevention efforts with additional waste management techniques
to further reduce emissions. These techniques, presented in order of preference, include
recycling, treatment, and disposal. This section presents waste management techniques typically
used by the PWB industry in the MHC process to minimize waste, recycle or recover valuable
process resources, and to control emissions to water and air.
6.2.1 Recycle and Resource Recovery Opportunities
PWB manufacturers have begun to reevaluate the merits of recycle and recovery
technologies because of more stringent effluent pretreatment regulations. Recycling is the in-
process recovery of process material effluent, either on-site or off-site, which would otherwise
become a solid waste, air emission, or a wastewater stream. Metals recycling and recovery
processes have become more economical to operate due to the increased cost of managing sludge
containing heavy metals under stricter regulatory requirements. Technologies that recycle water
from waste streams concentrate the final effluent making subsequent treatment more efficient,
thus reducing the volume of waste generated along with overall water and sewer costs. As a
result, these technologies are being used more frequently by industry to recycle or recover
valuable process resources while also minimizing the volume of waste that is sent to disposal.
This trend was supported by the respondents of the Printed Wiring Board Pollution Prevention
and Control: Analysis of Survey Results (EPA, 1995c), 76 percent of whom reported using some
type of recycle or resource recovery technology.
Recycle and resource recovery technologies include those that recover materials from
waste streams before disposal or recycle waste streams for reuse in another process.
Opportunities for both types of technologies exist within the MHC process. Rinse water can be
recycled and reused in further rinsing operations while copper can be recovered from waste
streams before disposal and sold to a metals reclaimer. These recycle and recovery technologies
may be either in-line (dedicated and built into the process flow of a specific process line) or at-
line (employed at the line as desired as well as other places in the plant) technologies depending
on what is required (Brooman, 1996). Each individual waste stream that cannot be prevented
should be evaluated to determine its potential for effective recycle or resource recovery.
The decision on whether to purchase a recycle or resource recovery process should be
based on several factors. Economic factors such as process operating costs and effluent disposal
costs for the current system must be compared with those estimated for the new technology. The
initial capital investment of the new technology along with any potential cost savings and the
length of the payback period must also be considered. Other factors such as the characteristics of
the waste stream(s) considered for treatment, the ability of the process to accept reused or
recycled materials, and the effects of the recycle or recovery technology on the overall waste
treatment process should also be considered.
The entire PWB manufacturing process must be considered when assessing the economic
feasibility of a recycle or resource recovery process. An individual recovery process can recover
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
copper from a single stream originating from the MHC process, or it may recover the metal from
streams that originate from other processes as well. Only by considering the new technology's
impact on the entire process, can an accurate and informed decision be made. While this section
focuses on technologies that could be used to recycle or recover resources from the waste streams
that are generated from the MHC process, many of these technologies are applicable to other
PWB process lines. Workplace practices that can lead to the recycle or reuse of resources (e.g.,
manually recovering copper from panel racks, water recycle using cascade water rinse systems)
are discussed in Section 6.1.
Reverse Osmosis
Reverse osmosis is a recovery process used by the PWB industry to regenerate rinse
waters and to reclaim process bath drag-out for return to the process (EPA, 1990). It relies on a
semi-permeable membrane to separate the water from metal impurities allowing bath solutions to
be reused. It can be used as a recycling or recovery technology to reclaim or regenerate a specific
solution, or it can be part of an overall waste treatment process to concentrate metals and
impurities before final treatment.
The reverse osmosis process uses a semi-permeable membrane which permits only
certain components to pass through it and a driving force to separate these components at a
useful rate. The membrane is usually made of a polymer compound (e.g., nylon) with hole sizes
ranging from 0.0004 to 0.06 microns in diameter. High pressure pumping of the waste stream, at
pressures typically ranging from 300 to 1,500 pounds per square inch (psi) force the solution
through the membrane (Capsule Environmental Engineering, Inc., 1993). The membrane allows
the water to pass while inhibiting the metal ions, collecting them on the membrane surface. The
concentrated metal ions are allowed to flow out of the system where they are reused as bath
make-up solution or are sent to treatment. The relatively pure water can be recycled as rinse
water or directly sewered.
The reverse osmosis process has some limitations. The types of waste streams suitable
for processing are limited to the ability of the plastic membranes to withstand the destructive
nature of the given waste stream. The membranes are sensitive to solutions with extreme pH
values, either low or high, which can degrade the polymer membranes. Pure organic streams are
likewise not treatable. Waste streams with suspended solids should be filtered prior to separation
to keep me solids from fouling the membrane, thus reducing the efficiency of the process.
Process membranes may also have a limited life due to the long-term pressure of the solution on
the membrane (Coombs, 1993). Data regarding the usage of reverse osmosis technology by
industry was not collected by the Pollution Prevention Survey.
Ion Exchange
Ion exchange is a process used by the PWB industry mainly to recover metal ions, such as
copper or palladium, from rinse waters and other solutions. This process uses an exchange resin
to remove the metal from solution and concentrate it on the surface of the resin. It is particularly
suited to treating dilute solutions, because it removes the metal species from the solution instead
of removing the solution from the metal. As a result, the relative economics of the process
improve as the concentration of the feed solution decreases. Aside from recovering copper, ion
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
exchange can also be used for treating wastewater, deionizing feed water, and recovering
chemical solutions.
Ion exchange relies on special resins, either cationic or anionic, to remove the desired
chemical species from solution. Cation exchange resins are used to remove positively charged
ions such as copper. When a feed stream containing copper is passed through a bed of cation
exchange resin, the resin removes the copper ions from the stream, replacing them with hydrogen
ions from the resin. For example, a feed stream containing copper sulfate (CuSO4) is passed
through the ion exchange resin where the copper ions are removed and replaced by hydrogen ions
to form sulfuric acid (H2SO4). The remaining water effluent is either further processed using an
anion exchange resin and then recirculated into the rinse water system, or pH neutralized and
then directly sewered. Ion exchange continues until the exchange resin becomes saturated with
metal ions and must be regenerated.
Special chelating resins have been designed to capture specific metal ions that are in the
presence of chelating agents, such as metal ions in electroless plating baths. These resins are
effective in breaking down the chemical complexes formed by chelators that keep metal ions
dissolved in solution, allowing them to be captured by the resin. They ignore hard water ions,
such as calcium and magnesium that would otherwise be captured, creating a more pure
concentrate. Chelating resins require that the feed stream be pH adjusted to reduce acidity and
filtered to remove suspended solids that will foul the exchange bed (Coombs, 1993).
Regeneration of the cation or chelating exchange resin is accomplished using a
moderately concentrated (e.g., ten percent) solution of a strong acid, such as sulfuric acid.
Regeneration reverses the ion exchange process by stripping the metal ions from the exchange
resin and replacing them with hydrogen ions from the acid. The concentration of metal ions in
the remaining regenerant depends on the concentration of the acid used, but typically ranges from
10 to 40 g/L or more (Coombs, 1993).
Ionic exchange can be combined with electrowinning (electrolytic recovery) to recover
metal from solutions that would not be cost-effective to recover using either technology alone. It
can be used to concentrate a dilute solution of metal ions for electrolytic recovery that would
otherwise be uneconomical to recover. For example, a dilute copper chloride solution can be
treated by an ion exchange unit which is regenerated using sulfuric acid, producing a
concentrated copper sulfate solution. The electrowinning unit can then be used to recover the
copper from the solution while regenerating the acid, which could then be used for the next
regeneration cycle.
A benefit of ion exchange is the ability to control the type of metallic salt that will be
formed by selecting the type of acid used to regenerate the resin. In the previous example, the
copper chloride was converted to copper sulfate while being concentrated by the ion exchange
system. This is particularly useful when electrowinning is used, since it cannot process solutions
containing the chlorine ion without generating toxic chlorine gas.
Twenty-six percent of the respondents to the Pollution Prevention Survey reported using
an ion exchange process as a water recycle/chemical recovery technology. The average capital
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
cost of a unit, which is related to its capacity, reported by the respondents was $47,500 with a
low of $5,000 and a high of $100,000.
Electrolytic Recovery
Electrolytic recovery, also known as electrowinning, is a common metal recovery
technology employed by the PWB industry. Operated either in continuous or batch mode,
electrowinning can be applied to various process fluids including spent microetch, drag-out rinse
water, and ion exchange regenerant. An advantage of electrowinning, which uses an electrolytic
cell to recover dissolved copper ions from solution, is its ability to recover only the metal from
solution without recovering the other impurities that are present. The recovered copper can then
be sold as scrap or reused in the process.
Process waste solutions containing chlorine ions in any form should not be processed
using electrolytic recovery methods since the electrolysis of these solutions could generate
chlorine gas. Solutions containing copper chloride salts should first be converted using ion
exchange methods to a non-chloride copper salt (e.g., copper sulfate) solutions before undergoing
electrowinning to recover the copper content (Coombs, 1993).
Electrowinning is most efficient with concentrated solutions. Dilute solutions with less
than 100 mg/L of copper become uneconomical to treat due to the high power consumption
relative to the amount of copper recovered (Coombs, 1993). Waste streams that are to be treated
should be segregated to prevent dilution and to prevent the introduction of other metal impurities.
Already diluted solutions can be concentrated first using ion exchange or evaporation techniques
to improve the efficiency and cost-effectiveness of metal recovery.
The electrolytic cell is comprised of a set of electrodes, both cathodes and anodes, placed
in the copper laden solution. An electric current, or voltage, is applied across the electrodes and
through the solution. The positively charged metal ions are drawn to the negatively charged
cathode where they deposit onto the surface. The solution is kept thoroughly mixed using air
agitation, or other proprietary techniques, which allow the process to use higher current densities
(the amount of current per surface area of cathode) that speed deposition time and improve
efficiency. As copper recovery continues, the concentration of copper ions in solution becomes
depleted, requiring the current density to be reduced to maintain efficiency. When the
concentration of copper becomes too low for its removal to be economically feasible, the process
is discontinued and the remaining solution is sent to final treatment.
The layers of recovered copper can be sold as scrap to a metals reclaimer. Copper
removal efficiencies of 90 to 95 percent have been achieved using electrolytic methods (EPA,
1990). The remaining effluent will still contain small amounts of copper and will be acidic in
nature (i.e., low pH). Adjusting the pH may not be sufficient for the effluent to meet the
standards of some POTW authorities; therefore, further treatment may be required.
Eighteen percent of the Pollution Prevention Survey respondents reported using
electro winning as a resource recovery technology with nearly all (89 percent) being satisfied.
The median cost of a unit reported by the respondents was $15,000; however, electrowinning
capital costs are dependant on the capacity of the unit.
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_ 6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
6.2.2 Control Technologies
If the release of a hazardous material cannot be prevented or recycled, it may be possible
to treat or reduce the impact of the release using a control technology. Control technologies are
engineering methods that minimize the toxicity and volume of released pollutants. Most of these
methods involve altering either the physical or chemical characteristics of a waste stream to
isolate, destroy, or alter the concentration of target chemicals. While this section focuses on
technologies that are used to control on-site releases from the MHC process, many of these
technologies are also applicable to other PWB process lines.
Control technologies are typically used to treat on-site releases to both water and air from
the operation of the MHC process. Wastewater containing concentrations of heavy metal ions,
along with chelators and complexing agents, are of particular concern. Water effluent standards
require the removal of most heavy metals and toxic organics from the plant effluent before it can
be disposed to the sewer. On-site releases to air of concern include formaldehyde vapors, as well
as acid and solvent fumes. The desire to eliminate both formaldehyde and chelating agents has
led to the development of alternative MHC processes. This section identifies the control
technologies used by PWB manufacturers to treat or control wastewater and air emissions
released by the operation of the MHC process.
Wastewater Treatment
Chemical Precipitation. In the PWB industry, the majority of facilities surveyed (61
percent) reported using a conventional chemical precipitation system to accomplish the removal
of heavy metal ions from wastewater. Chemical precipitation is a process for treating wastewater
that depends on the water solubility of the various compounds formed during treatment. Heavy
metal cations that are present hi the wastewater are reacted with certain treatment chemicals to
form metal hydroxides, sulfides, or carbonates that all have relatively low water solubilities. The
resulting heavy metal compounds are then precipitated from the solution as an insoluble sludge
that is subsequently recycled to reclaim the metals content or sent to disposal. The chemical
precipitation process can be operated as a batch process, but is typically operated in a continuous
process to treat wastewater.
In the chemical precipitation treatment of wastewater from PWB manufacturing, the
removal of heavy metals may be carried out by a unit sequence of rapid mix precipitation,
flocculation, and clarification. The process begins with the dispersion of treatment chemicals
into the wastewater input stream under rapid mixing conditions. The initial mixing unit is
designed to create a high intensity of turbulence in the reactor vessel, promoting encounters
between the metal ions and the treatment chemical species, which then react to form metal
compounds that are insoluble in water. The type of chemical compounds formed depends on the
treatment chemical employed; this is discussed in detail later in this section. These insoluble
compounds form a fine precipitate at low pH levels that remains suspended in the wastewater.
The wastewater then enters the flocculation tank. The purpose of the flocculation step is
to transform smaller precipitation particles into large particles that are heavy enough to be
removed from the water by gravity settling hi the clarification step. This particle growth is
accomplished in a flocculation tank using slow mixing to promote the interparticle collisions of
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
precipitate particles suspended in the wastewater. The degree of flocculation is enhanced
through the use of flocculating chemicals such as cationic or anionic polymers. These chemicals
promote interparticle adhesion by adding charged particles to the wastewater that attach
themselves to the precipitate, thereby increasing the growth rate of the precipitate particles.
Clarification is the final stage of the wastewater treatment process. The wastewater
effluent from the flocculation stage is fed into a clarification tank where the water is allowed to
collect undisturbed. The precipitate then settles out of the water by gravity, forming a blanket of
sludge at the bottom of the clarification tank. A portion of the sludge, typically 10 to 25 percent,
is often recirculated to the head of the flocculation step to reduce chemical requirements, as well
as to enhance the rate of precipitation (Frailey, 1996). The sludge particles provide additional
precipitation nuclei that increase the probability of particle collisions, resulting in a more dense
sludge deposit. When a dense layer of sludge has been formed, the sludge is removed from the
tank and is either dewatered or sent for recycle or disposal. The precipitate-free water is then
either recycled or sewered.
Other process steps are sometimes employed in the case of unusually strict effluent
guidelines. Filtration, reverse osmosis, ion exchange, or additional precipitation steps are
sometimes employed to further reduce the concentration of'chemical contaminants present in the
wastewater effluent.
The heavy metal sludge generated by the wastewater treatment process is often
concentrated, or dewatered, before being sent to recycle or disposal. Sludge can be dewatered in
several methods including sludge thickening, press filtration, and sludge drying. Through the
removal of water, sludge volume can be minimized, thus reducing the cost of disposal.
Treatment of Non-Chelated Wastewater. The absence of complexing chemicals (e.g.,
ammonia) or chelating agents (e.g., EDTA) in the wastewater stream simplifies the removal of
heavy metal ions by precipitation. Heavy metal removal from such waste streams is
accomplished through simple pH adjustment using hydroxide precipitation. Caustic soda
(NaOH) is typically used while other treatment chemicals include calcium hydroxide and
magnesium hydroxide. The heavy metal ions react with the caustic soda to form insoluble metal
hydroxide compounds that precipitate out of solution at a high pH level. After the precipitate is
removed by gravity settling, the effluent is pH adjusted to a pH of seven to nine and then
sewered. The treatment can be performed in a chemical precipitation process similar to the one
described above, resulting in a sludge contaminated with metals that is then sent to recycling or
disposal.
Treatment of Wastewater Containing Chelated Metals. The presence of complexing
chemicals or chelators require a more vigorous effort to achieve a sufficient level of heavy metal
removal. Chelators are chemical compounds that inhibit precipitation by forming chemical
complexes with the metals, allowing them to remain in solution beyond their normal solubility
limits. These chemicals are found in spent MHC plating baths, in cleaners, and in the water
effluent from the rinse tanks following these baths. Treatment chemicals enhance the removal of
chelated metals from water by breaking the chelant-to-metal bond, destroying the soluble
complex. The freed metal ions then react to form insoluble metal compounds, such as metal
hydroxides, that precipitate out of solution. Several different chemicals are currently being used
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6.2 RECYCLE. RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
to effectively treat chelator-contarninated wastewater resulting from the manufacture of PWBs.
Some common chemicals used in the treatment of wastewater produced by the MHC process are
briefly described in Table 6.6. For a more information regarding individual treatment chemicals
and their applicability to treating specific wastes, consult the supplier of the treatment chemical.
Table 6.6 Treatment Chemicals Used to Remove Heavy Metals From
Chelated Wastewater
Chemical
Ferrous Sulfate
DTC
(Dimethyl-dithiocarbamate)
Sodium Sulflde
Polyelectrolyte
Sodium Borohydride
Ferrous Dithionite
Description
Inexpensive treatment that requires iron concentrations in excess of 8: 1 to
form an insoluble metal hydroxide precipitate (Coombs, 1993). Ferrous
sulfate is first used as a reducing agent to breakdown the complexed
copper structures under acidic conditions before forming the metal
hydroxide during subsequent pH neutralization. Drawbacks include the
large volumes of sludge generated and the presence of iron which reduces
the value of sludge to a reclaimer.
Moderately expensive chemical that acts as a complexing agent, exerting
a stronger reaction to the metal ion than the chelating agent, effectively
forming an insoluble heavy metal complex. The sludge produced is light
in density and difficult to gravity separate (Guess, 1992; Frailey, 1996).
Forms heavy metal sulfides with extremely low solubilities that precipitate
even in the presence of chelators. Produces large volume of sludge that is
slimy and difficult to dewater (Guess, 1992).
Polymers that remove heavy metals effectively without contributing to the
volume of sludge. Primary drawback is the high chemical cost (Frailey,
1996).
Strong reducing agent reduces heavy metal ions which then precipitate out
of solution forming a compact, low volume sludge. Drawbacks include its
high chemical cost and the evolution of potentially explosive hydrogen gas
(Guess, 1992; Frailey, 1996).
Reduces heavy metal ions under acidic conditions to form metallic
particles that are recovered by gravity separation. Excess iron is
regenerated instead of being precipitated producing a low volume sludge
(Guess, 1992).
Effects of MHC Alternatives On Wastewater Treatment. The strong desire to remove
both formaldehyde and complexing chemicals, such as chelators, from the MHC process has led
the drive away from traditional electroless copper and toward the development of alternative
MHC processes. These processes eliminate the use of chelating agents that inhibit the
precipitation of heavy metal ions in wastewater. Also eliminated is the need for expensive
treatment chemicals, which are designed to breakdown chelators and which can add to the
quantity of sludge produced. The resulting treatment of the non-chelated waste stream produces
less sludge at a lower chemical treatment cost than it would if chelators were present. A detailed
description of the treatment for both chelated and non-chelated wastes is presented elsewhere in
this chapter.
While MHC alternative processes may reduce or eliminate the presence of chelators in
the wastewater, they do not create any additional treatment concerns that would require any
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
physical changes in the treatment process. The treatment of wastewater generated from the
operation of a MHC alternative can be accomplished using the traditional chemical precipitation
stages of rapid mix precipitation, flocculation, and clarification.
Alternative Treatment Processes. Although chemical precipitation is the most common
process for treating wastewater by PWB manufacturers, other treatment processes exist as well.
Survey respondents reported the use of both ion exchange (33 percent) and/or electro winning (12
percent) to successfully treat wastewater generated from the manufacture of PWBs. These
processes operate separately, or in combination, to efficiently remove heavy metal ions from
chelated or non-chelated waste streams, typically yielding a highly concentrated sludge for
disposal. These processes were discussed in Section 6.2.1.
Batch Treatment of Process Baths. Most spent process baths can be mixed with other
wastewater and treated by the on-site wastewater treatment process using chemical precipitation.
Chemical suppliers, however, recommend that some process baths be treated separately from the
usual waste treatment process. The separate treatment of these baths is usually recommended
due to the presence of strong chelating agents, high heavy metal concentrations, or other
chemicals, such as additives or brighteners, that require additional treatment measures before
they can be disposed of properly. Spent bath solution requiring special treatment measures can
be processed immediately, but is typically collected and stored until enough has accumulated to
warrant treatment. Batch treatment of the accumulated waste is then performed in a single tank
or drum, following the specific treatment procedures provided by the chemical supplier for that
bath.
Despite the supplier's recommendations, PWB facilities sometimes treat individual
process baths using their typical wastewater treatment process. Spent bath solutions can be
mixed slowly, in small quantities, with other wastewater before being treated, thus diluting the
concentration of the chemical species requiring treatment. However, the introduction of
concentrated wastes to the wastewater could result in increased treatment chemical consumption
and more sludge produced than if batch treated separately. Also the introduction of a chemical
species not typically found in the wastewater may adversely affect the treatment process or
require more vigorous treatment chemicals or processes. Factors affecting the success of such
treatment include the type of treatment chemicals used, the contaminant concentrations in the
wastewater, and the overall robustness of the treatment process.
Air Pollution Control Technologies
Air pollution control technologies are often used by the PWB industry to cleanse air
exhaust streams of harmful fumes and vapors. Exactly half (50 percent) of the PWB facilities
surveyed have installed air scrubbers to control air emissions from various manufacturing
processes, and almost a quarter of the facilities (23 percent) scrub air releases from the MHC
process. The first step of any air control process is the effective containment of fugitive air
emissions at their source of release. This is accomplished using fume hoods over the process
areas from which the air release of concern is emanating. These hoods may be designed to
continuously collect air emissions for treatment by one of the methods described below.
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6.2 RECYCLE, RECOVERY, AND CONTROL TECHNOLOGIES ASSESSMENT
Gas Absorption. One method for removing pollutants from an exhaust stream is by gas
absorption in a technique sometimes referred to as air scrubbing. Gas absorption is defined as
the transfer of material from a gas to a contacting liquid, or solvent. The pollutant is chemically
absorbed and dispersed into the solvent leaving the air free of the pollutant. The selection of an
appropriate solvent should be based upon the liquid's solubility for the solute, and the cost of the
liquid. Water is used for the absorption of water soluble gases while alkaline solutions are
typically used for the absorption of acid gases. Air scrubbers are used by the PWB industry to
treat wet process air emissions, such as formaldehyde and acid fumes, and emissions from other
processes outside the MHC process.
Gas absorption is typically carried out in a packed gas absorption tower, or scrubber. The
gas stream enters the bottom of the tower, and passes upward through a wetted bed of packing
material before exiting the top. The absorbing liquid enters the top of the tower and flows
downward through the packing before exiting at the bottom. Absorption of the air pollutants
occurs during the period of contact between the gas and liquid. The gas is either physically or
chemically absorbed and dispersed into the liquid. The liquid waste stream is then sent to water
treatment before being discharged to the sewer. Although the most common method for gas
absorption is the packed tower, other methods exist such as plate towers, sparged towers, spray
chambers, or venturi scrubbers (Cooper, 1990).
Gas Adsorption. The removal of low concentration organic gases and vapors from an
exhaust stream can be achieved by the process of gas adsorption. Adsorption is the process in
which gas molecules are retained on the interface surfaces of a solid adsorbent by either physical
or chemical forces. Activated carbon is the most common adsorbent but zeolites such as alumina
and silica are also used. Adsorption is used primarily to remove volatile organic compounds
from air, but is also used in other applications such as odor control and drying process gas
streams (Cooper, 1990). In the MHC process it can be used to recover volatile organic
compounds, such as formaldehyde.
Gas adsorption occurs when the vapor-laden air is collected and then passed through a
bed of activated carbon, or another adsorbent material. The gas molecules are adsorbed onto the
surface of the carbon, while the clean vapor-free air is exhausted from the system. The adsorbent
material eventually: becomes saturated with organic material and must be replaced or regenerated.
Adsorbent canisters, which are replaced on a regular basis, are typically used to treat small gas
flow streams. Larger flows of organic pollutants require packed beds of adsorbent material,
which must be regenerated when the adsorbent becomes saturated (Cooper, 1990).
Regeneration of the adsorbent is typically accomplished by a steam stripping process.
The adsorbent is contacted with low pressure steam which desorbs the adsorbed gas molecules
from the surface of the packed bed. Following condensation of the steam, the organic material is
recovered from the water by either decanting or distillation (Campbell, 1990).
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REFERENCES
REFERENCES
Bayes, Martin. 1996. Shipley Company. Personal communication to Jack Geibig, UT Center
for Clean Products and Clean Technologies. January.
Brooman, Eric. 1996. Concurrent Technologies Corporation. Personal communication to Lori
Kincaid, UT Center for Clean Products and Clean Technologies. August 5.
Campbell, M. and W. Glenn. 1982. "Profit from Pollution Prevention." Pollution Probe
Foundation.
Capsule Environmental Engineering, Inc. 1993. "Metal Finishing Pollution Prevention Guide."
Prepared for Minnesota Association of Metal Finishers in conjunction with The
Minnesota Technical Assistance Program. Prepared by Capsule Environmental
Engineering, Inc., 1970 Oakcrest Avenue, St. Paul, MN 55113. July.
Coombs, Jr., Clyde. 1993. Printed Circuits Handbook. 4th ed. McGraw-Hill.
Cooper, David C. and F.C. Alley. 1990. Air Pollution Control: A Design Approach. Waveland
Press, Prospect Heights, IL.
Edwards, Ted. 1996. Honeywell. Personal communication to Lori Kincaid, UT Center for
Clean Products and Clean Technologies. July 10.
Fehrer, Fritz. 1996. Silicon Valley Toxics Coalition. Personal communication to Lori Kincaid,
UT Center for Clean Products and Clean Technologies. July 22.
Frailey, Dean. 1996. Morton International. Personal communication to Jack Geibig, UT Center
for Clean Products and Clean Technologies. May 7.
Guess, Robert. 1992. Romar Technologies. United States Patent # 5,122,279. July 16.
Kling, David J. 1995. Director, Pollution Prevention Division, Office of Pollution Prevention
and Toxics. Memo to Regional OPPT, Toxics Branch Chiefs. February 17.
U.S. Environmental Protection Agency (EPA). 1990. Guides to Pollution Prevention: The
Printed Circuit Board Manufacturing Industry. EPA Office of Resource and
Development, Cincinnati, OH. EPA/625/7-90/007. June.
U.S. Environmental Protection Agency (EPA). 1995a. "Printed Wiring Board Case Study 1:
Pollution Prevention Work Practices." Pollution Prevention Information Clearinghouse
(PPIC). Washington, D.C. EPA 744-F-95-004. July.
U.S. Environmental Protection Agency (EPA). 1995b. "Printed Wiring Board Case Study 2:
On-Site Etchant Regeneration." Pollution Prevention Information Clearinghouse (PPIC).
Washington, D.C. EPA 744-F-95-005. July.
6-26
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REFERENCES
U.S. Environmental Protection Agency (EPA). 1995c. Printed Wiring Board Pollution
Prevention and Control: Analysis of Survey Results. Design for the Environment Printed
Wiring Board Project. EPA Office of Pollution Prevention and Toxics. Washington,
D.C. EPA 744-R-95-006. September.
U.S. Environmental Protection Agency (EPA). 1995d. Federal Environmental Regulations
Affecting the Electronics Industry, EPA Office of Pollution Prevention and Toxics.
Washington, D.C. EPA744-B-95-001. September.
U.S. Environmental Protection Agency. (EPA). 1996a. "Printed Wiring Board Project:
Opportunities for Acid Recovery and Management." Pollution Prevention Information
Clearinghouse (PPIC). Washington, D.C. EPA 744-F-95-009. September.
U.S. Environmental Protection Agency. (EPA). 1996b. "Printed Wiring Board Project: Plasma
Desmear: A Case Study." Pollution Prevention Information Clearinghouse (PPIC).
Washington, D.C. EPA744-F-96-003. September.
U.S. Environmental Protection Agency. (EPA). 1996c. "Printed Wiring Board Project: A
Continuous-Flow System for Reusing Microetchant." Pollution Prevention Information
Clearinghouse (PPIC). Washington, D.C. EPA 744-F-96-024. December.
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REFERENCES
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Chapter 7
Choosing Among MHC Technologies
This chapter of the Cleaner Technologies Substitutes Assessment (CTSA) organizes data
collected or developed throughout the assessment of the baseline non-conveyorized electroless
copper process and alternatives in a manner that facilitates decision-making. First, risk,
competitiveness, and conservation data are summarized in Section 7.1. This information is used
in Section 7.2 to assess the net benefits and costs to society of implementing an alternative as
compared to the baseline. Section 7.3 provides summary profiles for the baseline and
alternatives.
Information is presented for eight technologies for performing the making holes
conductive (MHC) function. These technologies are electroless copper, carbon, conductive ink,
conductive polymer, graphite, non-formaldehyde electroless copper, organic-palladium, and tin-
palladium. All of these technologies are wet chemistry processes, except the conductive ink
technology, which is a screen printing technology.1 The wet chemistry processes can be operated
using vertical, immersion-type, non-conveyorized equipment or horizontal, conveyorized
equipment.2 Table 7.1 presents the processes (alternatives and equipment configurations)
evaluated in the CTSA.
Table 7.1 MHC Processes Evaluated in the CTSAa
MHC Technology
Electroless Copper (BASELINE)
Carbon
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
Equipment Coaiigwration
Ntm-Ojwveyorizied
/
/
/
/
Co»veyorizied
/
/
/
/
/
/
The human health and aquatic toxicity hazards and chemical safely hazards of the conductive ink technology were
also evaluated, but risk was not characterized.
1 Only limited analyses were performed on the conductive ink technology for two reasons: 1) the process
is not applicable to multi-layer boards, which were the focus of the CTSA; and 2) sufficient data were not available
to characterize the risk, cost, and energy and natural resources consumption of all of the relevant process steps (e.g.,
preparation of the screen for printing, the screen printing process itself, and screen reclamation).
2 Conveyorized MHC equipment is a relatively new innovation in the industry, and is usually more
efficient than non-conveyorized equipment. Many of the newer technologies are only being used with conveyorized
equipment, while most facilities in the U. S. still use a non-conveyorized electroless copper process to perform the
MHC function.
~
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
The results of the CTSA suggest that the alternatives not only have environmental and
economic benefits compared to the non-conveyorized electroless copper process, but also
perform the MHC function as well as the baseline. While there appears to be enough
information to show that a switch away from traditional electroless copper processes has reduced
risk benefits, there is not enough information to compare the alternatives to this process among
themselves for all their environmental and health consequences. This is due to a lack of
proprietary chemical data from some suppliers3 and because toxicity values are not available for
some chemicals. In addition, it is important to note that there are additional factors beyond those
assessed in this CTSA which individual businesses may consider when choosing among
alternatives. None of these sections make value judgements or recommend specific alternatives.
The actual decision of whether or not to implement an alternative is made outside of the CTSA
process.
7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Earlier sections of the CTSA evaluated the risk, performance, cost, and resource
requirements of the baseline MHC technology as well as the alternatives. This section
summarizes the findings associated with the analysis of MHC technologies. Relevant data
include the following:
• Risk information: occupational health risks, public health risks, ecological hazards, and
process safety concerns.
• Competitiveness information: technology performance, cost and regulatory status, and
international information.
• Conservation information: energy and natural resource use.
Sections 7.1.1 through 7.1.3 present risk, competitiveness, and conservation summaries,
respectively.
7.1.1 Risk Summary
This risk characterization uses a health-hazard based framework and a model (generic)
facility approach to compare the health risks of one MHC process technology to the health risks
associated with switching to an alternative technology. As much as possible, reasonable and
consistent assumptions are used across alternatives. Data to characterize the model facility and
exposure patterns for each process alternative were aggregated from a number of sources,
including printed wiring board (PWB) shops in the U.S. and abroad, supplier data, and input
from PWB manufacturers at project meetings. Thus, the model facility is not entirely
3 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project. Atotech provided information on one proprietary ingredient. W.R. Grace was
preparing to provide proprietary information on chemical ingredients in the conductive ink technology when it was
determined that this information was no longer necessary because risk from the conductive ink technology could not
be characterized. The other suppliers participating in the project (Enthone-OMI, MacDermid, and Shipley) declined
to provide proprietary information.
-_
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
representative of any one facility, and actual risk could vary substantially, depending on site-
specific operating conditions and other factors.
When using the results of the risk characterization to compare health effects among
alternatives, it is important to remember that it is a screening level rather than a comprehensive
risk characterization, both because of the predefined scope of the assessment and because of
exposure and hazard data limitations. It should also be noted that this approach does not result in
any absolute estimates or measurements of risk, and even for comparative purposes there are
several important uncertainties associated with this assessment (see Section 3.4).
The exposure assessment for the risk characterization used, whenever possible, a
combination of central tendency and high-end assumptions (i.e., 90 percent of actual values are
expected to be less) to yield an overall high-end exposure estimate. Some values used in the
exposure calculations, however, are better characterized as "what-if,"4 especially pertaining to
bath concentrations, use of gloves, and process area ventilation rates for a model facility.
Because some part of the exposure assessment for both inhalation and dermal exposures qualifies
as a "what-if descriptor, the entire assessment should be considered "what-if."
As with any risk characterization, there are a number of uncertainties involved in the
measurement and selection of hazard data, and in the data, models, and scenarios used in the
exposure assessment. Uncertainties arise both from factors common to all risk characterizations
(e.g., extrapolation of hazard data from animals to humans, extrapolation from the high doses
used in animal studies to lower doses to which humans may be exposed, missing toxicity data,
including data on the cumulative or synergistic effects of chemical exposure), and other factors
that relate to the scope of the risk characterization (e.g., the MHC characterization is a screening
level characterization rather than a comprehensive risk assessment). Key uncertainties in this
characterization include the following:
• The risk characterization of products supplied by Enthone-OMI, MacDermid, Shipley,
and, to some degree, Atotech, is based on publicly-available bath chemistry data, which
do not include the identity or concentrations of chemicals considered trade secrets by
chemical suppliers.5
• The risk estimates for occupational dermal exposure are based on limited dermal toxicity
data, using oral toxicity data with oral to dermal extrapolation when dermal toxicity data
were unavailable. Coupled with the high uncertainty in estimating dermal absorption
rates, this could result in either over- or under-estimates of exposure and risk.
4 A "what-if' description represents an exposure estimate based on postulated questions, making
assumptions based on limited data where the distribution is unknown.
5 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project for evaluation in the risk characterization. Atotech provided information on one
proprietary ingredient. Risk results for proprietary ingredients in chemical products submitted by these suppliers,
but not chemical identities or concentrations, are included in this CTSA.
_ - :-—
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
• The risk characterization is based on modeled estimates of average, steady-state chemical
concentrations in air, rather than actual monitoring data of average and peak air
concentrations.
• The risk characterization does not account for any side reactions occurring in the baths,
which could either underestimate exposures to toxic reaction products or overestimate
exposures to toxic chemicals that react in the bath to form more benign chemicals.
• Due to resource constraints, the risk characterization does not address all types of
exposures that could occur from MHC processes or the PWB industry, including short-
term or long-term exposures from sudden releases due to fires, spills, or periodic releases.
The Risk Characterization section of the CTSA (Section 3.4) discusses the uncertainties in this
characterization in detail.
Occupational Health Risks
Health risks to workers were estimated for inhalation exposure to vapors and aerosols
from MHC baths and for dermal exposure to MHC bath chemicals. Inhalation exposure
estimates are based on the assumptions that emissions to indoor air from conveyorized lines are
negligible, that the air in the process room is completely mixed and chemical concentrations are
constant over time, and that no vapor control devices (e.g., bath covers) are used in non-
conveyorized lines. Dermal exposure estimates are based on the assumption that workers do not
wear gloves6 and that all non-conveyorized lines are operated by manual hoist. Dermal exposure
to line operators on non-conveyorized lines could occur from routine line operation and
maintenance (e.g., bath replacement, filter replacement, etc.). Dermal exposure to line operators
on conveyorized lines was assumed to occur from bath maintenance activities alone.
Risk results indicate that alternatives to the non-conveyorized electroless copper process
pose lower occupational risks due to reduced cancer risks and to the reduced number of
inhalation and dermal risk concerns for the alternatives. However, there are occupational
inhalation risk concerns for some chemicals in the non-formaldehyde electroless copper and tin-
palladium non-conveyorized processes. In addition, there are occupational risk concerns for
dermal contact with some chemicals in the conveyorized electroless copper process, the non-
conveyorized non-formaldehyde electroless copper process, and tin-palladium and organic-
palladium processes for either conveyorized or non-conveyorized equipment. Finally,
occupational health risks could not be quantified for one or more of the chemicals used in each of
the MHC technologies. This is due to the fact that proprietary chemicals in the baths were not
identified by some suppliers and to missing toxicity or chemical property data for some
chemicals known to be present in the baths.
Table 7.2 presents chemicals of concern for potential occupational risk from inhalation.
Table 7.3 presents chemicals of concern for potential occupational risk from dermal contact.
6 Many PWB manufacturers report that their employees routinely wear gloves in the process area.
However, risk from dermal contact was estimated assuming workers do not wear gloves to account for those
workers who do not wear proper personal protective equipment
__
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7.1 RISK. COMPETITIVENESS,AND CONSERVATION DATA SUMMARY
Table 7.2 MHC Chemicals of Concern for Potential Occupational Inhalation Risk
Chemical"
Alkene Diol
Copper Chloride
Ethanolamine
2-Ethoxyethanol
Ethylene Glycol
Formaldehyde
Formic Acid
Methanol
Sodium Hydroxide
Sulfuric Acid0
Non-Conveyorteed Process1'
FJectroless Copper
•
•
•
•
•
•
•
•
•
•
Non-Formaldehyde Eieetroless Copper
•
Tin-PaHadiam
•
•
J_'\JJ_ LGWlJJLlVJiAJftlwO VVAU11 JJ.l\JJ.\r U.J.U1J. W4..1.V WJ.JLV.U.I-I-WM. hru^r^r^AwA y—.^.j •—-j.— — —. ~~ — ~-~- f ± A '*
concem that are present in all of the product lines evaluated are indicated in bold.
b Occupational inhalation exposure from conveyorized lines was assumed to be negligible.
c Sulfuric acid was listed on the MSDSs for all of the electroless copper lines evaluated and four of the five tin-
palladium lines evaluated.
Table 7.3 MHC Chemicals of Concern for Potential Occupational Dermal Risk
Chemical*
Copper Chloride
Fluoroboric Acid
Formaldehyde
Nitrogen Heterocycle
Palladium11
Palladium Chloride"
Palladium Salt
Sodium Carboxylate
Sodium Chlorite
Stannous Chloride0
Tin Salt
Eleptrolesis Copper
Line
Operator
NC
•
•
•
•
•
•
•
•
C
•
•
•
•
•
•
•
•
Lab Tech
(NCorC)
•
•
•
Non-Formaldehyde
Eleetrofess Copper
Line Operator
•
•
Iltt-PaJladlttm
Line
Operator
NC
•
•
•
•
•
C
•
•
•
•
•
Lah Tech
(NCwC)
•
•
•
•
Organic-Palladium
Line
Operator
NC
•
C
•
Lab Tech
iJ^CorC)
•
J_- tJJL \&\s±m\Jl\JfajL\s\J VV J.LJ.JL Ai-iVyj. w U.J.UJ.J. T~rj.i.v «^j. J.%AI.JL i-i.*- wj. I-F •--J-'^' -"-—•*• \—*O ' JT JT -— - - j. ^-
concern that are present in all of the product lines evaluated are indicated in bold.
b Palladium or palladium chloride was listed on the MSDSs for three of the five tin-palladium lines evaluated. The
MSDSs for the two other lines did not list a source of palladium. Palladium and palladium chloride are not listed on
the MSDSs for all of the electroless copper lines evaluated.
0 Stannous chloride was listed on the MSDSs for four of the five tin-palladium lines evaluated. The MSDSs for the
remaining line did not list a source of tin. Stannous chloride is not listed on the MSDSs for all of the electroless
copper lines evaluated.
NC: Non-Conveyorized.
C: Conveyorized.
7-5
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
The non-conveyorized electroless copper process contains the only non-proprietary
chemical for which an occupational cancer risk has been estimated (for formaldehyde).
Formaldehyde has been classified by EPA as Group Bl, a Probable Human Carcinogen. The
upper bound excess individual cancer risk estimate for line operators in the non-conveyorized
electroless copper process from formaldehyde inhalation may be as high as one in 1,000, but may
be 50 times less, or one in 50,000.7 Risks to other workers were assumed to be proportional to
the amount of time spent in the process area, which ranged from three percent to 61 percent of
the risk for a line operator.
Inhalation cancer risk was also estimated for one proprietary chemical, alkyl oxide, in the
non-conveyorized electroless copper process. The line operator inhalation exposure estimate for
alkyl oxide results in an estimated upper bound excess individual life time cancer risk of 3 x 10"7
(one in three million) based on high end exposure. Cancer risks less than 1 x 10"6 (one in one
million) are generally considered to be of low concern.
Additionally, dermal cancer risks were estimated for two proprietary chemicals, cyclic
ether and alkyl oxide, hi the graphite and electroless copper processes. For the conveyorized
graphite process, the dermal cancer risks for a line operator may be as high as 8 x 10"8 (about one
in ten million) for the alkyl oxide and 1 x 10"7 (one in ten million) for the cyclic ether. The upper
bound cancer risks for a laboratory technician were much less than the cancer risks for a line
operator. The cancer risks for a laboratory technician were 6 x 10"9 (one in 200 million) for alkyl
oxide and 9 x 10"9 (one in 100 million) for cyclic ether.
For non-conveyorized electroless copper, the dermal cancer risks for the line operator
may be as high as 4 x 10"7 (one in two million) for cyclic ether and 1 x 10"8 (one in 100 million)
for alkyl oxide. The estimated upper bound cancer risks for a laboratory technician were much
less than the cancer risks for a line operator. The estimated cancer risks for a laboratory
technician were 9 x 10"9 (one hi 100 million) for cyclic ether and 1 x 10"10 (one in ten billion) for
alkyl oxide.
For conveyorized electroless copper, the dermal cancer risk for a line operator may be as
high as 8 x 10"8 (about one in ten million) for cyclic ether and 4 x 10"9 (one in 200 million) for
alkyl oxide. The estimated upper bound cancer risks for a laboratory technician were much less
than the cancer risks for a line operator. The estimated cancer risks for a laboratory technician
were 9 x 10"9 (one in 100 million) for cyclic ether and 1 x 10"10 (one in ten billion) for alkyl
oxide.
Other non-proprietary chemicals in the MHC processes are suspected carcinogens.
Dimethyh^ormamide and carbon black have been determined by the International Agency for
Research on Cancer (IARC) to possibly be carcinogenic to humans (IARC Group 2B). Like
formaldehyde, the evidence for carcinogenic effects is based on animal data. However, unlike
7 To provide further information on the possible variation of formaldehyde exposure and risk, an
additional exposure estimate was provided in the Risk Characterization (Section 3.4) using average and median
values (rather than high-end) as would be done for a central tendency exposure estimate. This results in
approximately a 35-fold reduction in occupational formaldehyde exposure and risk from the estimates presented
here.
—_
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
formaldehyde, slope factors are not available for either chemical. There are potential cancer risks
to workers from both chemicals, but they cannot be quantified. Dimethylformamide is used in
the electroless copper process. Workplace exposures have been estimated but cancer potency
and cancer risk are unknown. Carbon black is used in the carbon and conductive ink processes.
Occupational exposure due to air emissions from the carbon baths in the carbon process is
expected to be negligible because this process is typically conveyorized and enclosed. There
may be some airborne carbon black, however, from the drying oven steps. Exposures from
conductive ink were not characterized. One proprietary chemical used in the electroless copper
process, trisodium acetate amine B, was determined to possibly be carcinogenic to humans but
does not have an established slope factor.
Public Health Risks
Public health risk was estimated for inhalation exposure only for the general populace
living near a facility. Environmental releases and risk from exposure to contaminated surface
water were not quantified due to a lack of data; chemical constituents and concentrations in
wastewater could not be adequately characterized. Public health risk estimates are based on the
assumption that emissions from both conveyorized and non-conveyorized process configurations
are steady-state and vented to the outside. Risk was not characterized for short-term exposures to
high levels of hazardous chemicals when there is a spill, fire, or other releases.
The risk indicators for ambient exposures to humans, although limited to airborne
releases, indicate low concern from all MHC technologies for nearby residents. The upper bound
excess individual cancer risk from formaldehyde inhalation for nearby residents from the non-
conveyorized electroless copper process was estimated to be from approaching zero to 1 x 10'7
(one in ten million), and from approaching zero to 3 x 10 '7 (one in three million) for the
conveyorized electroless copper process. Formaldehyde has been classified by EPA as Group
Bl, a Probable Human Carcinogen. The risk characterization for ambient exposure to MHC
chemicals also indicates low concern from the estimated air concentrations for chronic non-
cancer effects. The upper bound excess individual cancer risk for nearby residents from alkyl
oxide in the conveyorized graphite process was estimated to be from approaching zero to
9 x 10'11 (one in 11 billion); in the non-conveyorized electroless copper process from
approaching zero to 1 x 10'11 (one in 100 billion); and in the conveyorized electroless copper
process from approaching zero to 3 x 10'11 (one in 33 billion). All hazard quotients are less than
one for ambient exposure to the general population, and all MOEs for ambient exposure are
greater than 1,000 for all processes, indicating low concern from the estimated air concentrations
for chronic non-cancer effects.
Ecological Hazards
The CTSA methodology typically evaluates ecological risks in terms of risks to aquatic
organisms in streams that receive treated or untreated effluent from manufacturing processes.
Stream concentrations of MHC chemicals were not available, however, and could not be
estimated because of insufficient chemical characterization of constituents and their
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
concentrations in facility wastewater.8 To qualitatively assess risk to aquatic organisms, MHC
chemicals were ranked based on aquatic toxicity values according to established EPA criteria for
aquatic toxicity of high, moderate, or low concern (see Section 3.3.3).
Table 7.4 presents the number of MHC chemicals evaluated for each alternative, the
number of chemicals in each alternative with aquatic toxicity of high, moderate, or low concern,
the chemicals with the lowest concern concentration (CC) by alternative, and the bath
concentrations of the chemicals with the lowest CC. The aquatic toxicity concern level could
not be evaluated for some chemicals that have no measured aquatic toxicity data or established
structure-activity relationships to estimate their aquatic toxicity. Aquatic toxicity rankings are
based only on chemical toxicity to aquatic organisms, and are not an expression of risk.
Table 7.4 Aquatic Hazard Data
Alternative
Electro-less Copper
Carbon
Conductive Ink
Conductive
Polymer
Graphite
Non-Formaldehyde
Electroless Copper
Organic-Palladium
Tin-Palladium
No. of
Chemicals
Evaluated9
50C
8°
11°
6
13
10
7
26°
No. of Chemicals
by Aquatic Hazard
Concern Level"
High
9
2
2
0
3
3
2
9
Moderate
19
2
1
1
3
3
3
6
Low
21
3
7
5
7
4
2
10
Chemical wMh
Lowest CC
copper sulfate
(0.00002 mg/1)
copper sulfate
(0.00002 mg/1)
silver
(0.000036 mg/1)
peroxymonosulfuric acid
(0.030 mg/1)
copper sulfate
(0.00002 mg/1)
copper sulfate
(0.00002 mg/1)
sodium hypophosphite
(0.006 mg/1)
copper sulfate
(0.00002 mg/1)
Bath
Concentration
of Chemical
With Lowest CCb
4.8 to 12 g/1
5.0 g/1
NA
26.85 g/1
2.7 g/1
22 g/1
75 g/ld
0.2 to 13 g/1
* This includes chemicals from both publicly-available and proprietary data. This indicates the number of unique
chemicals; there is some overlap between public and proprietary lists for electroless copper. For technologies with
more than one chemical supplier (e.g., electroless copper, graphite, and tin-palladium), all chemicals may not be
present in any one product line.
b Bath concentrations are shown as a range for technologies supplied by more than one chemical supplier and are
based on publicly-available bath chemistry data.
0 No aquatic hazard data available for one chemical.
4 Chemical is in microetch bath. Concentration in bath may be overestimated, because MSDS reports both
chemicals in bath (sodium persulfate and sodium bisulfate) are present in concentrations < 75 percent (< 75 g/1).
NA: Not Applicable.
8 There are well-documented copper pollution problems associated with discharges to surface waters and
many of the MHC alternatives contain copper compounds. However, there were no data available to estimate the
relative concentration of copper in different MHC line effluents. In addition, no data were available for surface
water concentrations of other chemicals, especially chemicals in alternatives to electroless copper processes. Thus,
risk to aquatic organisms were not characterized.
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7.1 RISK. COMPETITIVENESS) AND CONSERVATION DATA SUMMARY
A CC is the concentration of a chemical in the aquatic environment which, if exceeded,
may result in significant risk to aquatic organisms. CCs were determined by dividing acute or
chronic toxicity values by an assessment factor (ranging from one to 1,000) that incorporates the
uncertainty associated with toxicity data. CCs are discussed in more detail in Section 3.3.3.
The number of chemicals with a high aquatic hazard concern level include nine in the
electroless copper process, two in carbon, two in conductive ink, none in conductive polymer,
three in graphite, three in non-formaldehyde electroless copper, two in organic-palladium, and
nine in tin-palladium. However, for technologies supplied by more than one chemical supplier
(e.g., electroless copper, graphite, and tin-palladium), all chemicals of high aquatic toxicity
concern may not be present in any one product line. The lowest CC is for copper sulfate, which
is found in five of the MHC technology categories: carbon, electroless copper, graphite, non-
formaldehyde electroless copper, and tin-palladium. Bath concentrations of copper sulfate vary,
ranging from a high of 22 g/1 for the non-formaldehyde electroless copper technology to a low of
0.2 g/1 in one of the tin-palladium processes (and, based on MSDS data, not present in the
conductive ink, organic-palladium, or conductive polymer processes).
Process Safety
Workers can be exposed to two types of hazards affecting occupational safety and health:
chemical hazards and process hazards. Workers can be at risk through exposure to chemicals and
because they work in proximity to automated equipment. In order to evaluate the chemical
safety hazards of the various MHC technologies, MSPSs for chemical products used with each
of the MHC technologies were reviewed. Table 7.5 summarizes the hazardous properties of
MHC chemical products.
Table 7.5 Hazardous Properties of MHC Chemical Products
MHC Technology
Electroless Copper
Carbon
Conductive Ink
Conductive
Polymer0
Graphite
Non-Formaldehyde
Electroless Copper
Organic-Palladium0
Tin-Palladium
No. of
MSDSs
Reviewed11
68
11
5
8
12
19
8
38
Number of Chemical Products with Hazardous Properties*
Flammable
7
7
0
1
0
3
0
2
Combustible
1
0
0
0
0
0
0
1
Explosive
1
0
5
0
0
0
0
1
Fire
Hazard
1
0
0,
0
1
0
0
1
Corrosive
29
5
0
5
4
4
0
12
Qxidizer
6
2
0
0
1
3
0
0
For technologies with more than one chemical supplier (e.g., electroless copper, graphite, and tin-palladium), all
chemicals with hazardous properties may not be present in any one product line.
b Reflects the combined number of MSDSs for all product lines evaluated in a technology category.
c Based on German equivalent of MSDS, which may not have as stringent reporting requirements as U.S. MSDS.
7-9
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Table 7.5 Hazardous Properties of MHC Chemical Products (cont.)
MHC Technology
Electroless Copper
Carbon
Conductive Ink
Conductive
Polymer0
Graphite
Non-Formaldehyde
Slectroless Copper
Organic-Palladium0
Fin-Palladium
No, of
usms
Reviewed11
68
11
5
8
12
19
8
38
Number of Chemical Products with Hazardous Properties'
Reactive
16
2
0
0
0
4
0
3
Unstable
1
0
0
0
1
0
1
0
Sensirizer
0
0
0
0
0
0
0
2
Acute Health
Hazard
14
11
0
0
8
9
0
9
Chrome Health
Hazard
10
9
0
0
4
5
0
5
Eye
Damage
34
12
2
6
4
7
4
22
*^ ^^ -—--—-~- ——j-j..j.j.->j. \*"^>3 v*.wt*.*jj.**tjtj v\jj./j,/WAJ gji t*pj.jj.t,v^j cu.jx* 1.1 ii—i J
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
7.1.2 Competitiveness Summary
The competitiveness summary provides information on basic issues traditionally
important to the competitiveness of a business: the performance characteristics of its products
relative to industry standards; the direct and indirect costs of manufacturing its products; its need
or ability to comply with environmental regulations; and factors influencing world-wide markets
for its products or technologies that may affect its competitiveness. The final evaluation of a
technology involves considering these traditional competitiveness issues along with issues that
business leaders now know are equally important competitiveness issues: the health and
environmental impacts of alternative products, processes, and technologies.
Performance
The performance of the MHC technologies was tested using production run tests. In
order to complete this evaluation, PWB panels, designed to meet industry "middle-of-the-road"
technology, were manufactured at one facility, run through individual MHC lines at 26 facilities,
then electroplated at one facility. The panels were electrically prescreened, followed by
electrical stress testing and mechanical testing, in order to distinguish variability in the
performance of the MHC interconnect. The test methods used to evaluate performance were
intended to indicate characteristics of a technology's performance, not to define parameters of
performance or to substitute for thorough on-site testing; the study was intended to be a
"snapshot" of the technologies. The Performance Demonstration was conducted with extensive
input and participation from PWB manufacturers, their suppliers, and PWB testing laboratories.
The technologies tested included electroless copper (the baseline), carbon, conductive
ink9, conductive polymer, graphite, non-formaldehyde electroless copper, and palladium.10 The
test vehicle was a 24 x 18" 0.062" 8-layer panel. (See Section 4.1 for a detailed description of
the test vehicle.) Each test site received three panels for processing through the MHC line.
Test sites were submitted by suppliers of the technologies, and included production
facilities, testing facilities (beta sites), and supplier testing facilities. Because the test sites were
not chosen randomly, the sample may not be representative of all PWB manufacturing facilities
(although there is no specific reason to believe that they are not representative). In addition, the
number of test sites for each technology ranged from one to ten. Due to the smaller number of
test sites for some technologies, results for these technologies could more easily be due to chance
than the results from technologies with more test sites. Statistical relevance could not be
determined.
9 The conductive ink test panels were processed through the MHC process and sent for testing. The
supplier of the technology felt that because the test vehicle used was incompatible with the capabilities of the
conductive ink technology, the test results were not indicative of the capabilities of the technology. Therefore, the
results of the conductive ink technology are not reported.
10 The Performance Demonstration included both organic and tin-palladium processes in the overall
palladium category.
___
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Product performance for this study was divided into two functions: plated-through hole
(PTH) cycles to failure and the integrity of the bond between the internal lands (post) and PTH
(referred to as "post separation"). The PTH cycles to failure observed in this study is a function
of both electrolytic plating and the MHC process. The results indicate that each MHC
technology has the capability to achieve comparable (or superior) levels of performance to
electroless copper. Post separation results indicated percentages of post separation that were
unexpected by many members of the industry. It was apparent that all MHC technologies,
including electroless copper, are susceptible to this type of failure.
Cost
Comparative costs were estimated using a hybrid cost model which combined traditional
costs with simulation modeling and activity-based costs. The cost model was designed to
determine the total cost of processing a specific amount of PWB through a fully operational
MHC line, in this case, 350,000 surface square feet (ssf). Total costs were divided by the
throughput (350,000 ssf) to determine a unit cost in $/ssf. The cost model did not estimate start-
up costs for a facility switching to an MHC alternative or the cost of other process changes that
may be required to implement an MHC alternative.
The cost components considered include capital costs (primary equipment, installation,
and facility costs), materials costs (limited to chemical costs), utility costs (water, electricity, and
natural gas costs), wastewater cost (limited to wastewater discharge cost), production costs
(production labor and chemical transport costs), and maintenance costs (tank cleanup, bath setup,
sampling and analysis, and filter replacement costs). Other cost components may contribute
significantly to overall costs, but were not quantified because they could not be reliably
estimated. These include wastewater treatment cost, sludge recycling and disposal cost, other
solid waste disposal costs, and quality costs. However, Performance Demonstration results
indicate that each MHC technology has the capability to achieve comparable levels of
performance to electroless copper. Thus, quality costs are not expected to differ among the
alternatives.
Table 7.6 presents results of the cost analysis, which indicate all of the alternatives are
more economical than the non-conveyorized electroless copper process. In general,
conveyorized processes cost less than non-conveyorized processes. Costs ranged from $0.51/ssf
for the baseline process to $0.09/ssf for the conveyorized conductive polymer process. Seven
process alternatives cost less than or equal to $0.20/ssf (conveyorized carbon at $0.18/ssf,
conveyorized conductive polymer at $0.09/ssf, conveyorized electroless copper at $0.15/ssf,
conveyorized organic-palladium at $0.17/ssf, non-conveyorized organic-palladium at $0.15/ssf,
and conveyorized and non-conveyorized tin-palladium at $0.12/ssf and $0.14/ssf, respectively).
Three processes cost more than $0.20/ssf; all of these processes are non-conveyorized (non-
conveyorized electroless copper at $0.51/ssf, non-conveyorized non-formaldehyde electroless
copper at $0.40/ssf, and conveyorized graphite at $0.22/ssf).
TIT
-------
7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Table 7.6 Cost of MHC Technologies
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicals
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Line Operation
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Unit Cost ($/ssf)
Electroless Copper,
non-eonveyorized
$64,000
$11,200
$8,690
$22,500
$6,540
$2,780
$0
. $13,700
$737
$36,100
$5,430
$1,220
$4,260
$2,800
$180,000
$0.51
Carbon,
conveyorized
$7,470
$299
$2,690
$32,900
$725
$836
$418
$1,710
$446
$10,200
$3,280
$740
$405
$116
$62,200
$0.18
Conductive Polymer,
eoffveyorized
$5,560
$0
$2,250
$10,400
$410
$460
$0
$965
$673
$5,830
$4,960
$1,120
$436
$376
$33,400
$0.09
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
, Cost Components
Primary Equipment
Installation
Facility
Chemicals
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Line Operation
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Unit Cost ($/ssf)
Electroless
Copper,
conveyorized
$6,190
. $212
$2,800
$22,600
$642
$669
$0
$1,450
$883
$7,230
$6,500
$1,460
$942
$612
$52,200
$0.15
Graphite,
coaveyorized
$3,580
$131
$1,090
$59,800
$251
$462
$145
$612
$319
$6,700
$2,350
$529
$316
$901
$77,200
$0.22
Non-Formaldehyde
Electroless Copper^
non-conveyorized
$29,300
$5,120
$3,350
$69,600
$2,100
$1,310
$0
$4,520
$682
$16,200
$5,030
$1,130
$691
$214
$139,200
$0.40
7-13
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7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Table 7.6 Cost of MHC Technologies (cont.)
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicals
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Line Operation
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Unit Cost ($/ssf)
Organic-Palladium,
conveyorized
$5,780
$356
$2,220
$28,900
$635
$720
$0
$1,510
$1,260
$6,530
$9,250
$2,080
$411
$271
$59,900
$0.17
Organic-Palladium,
non-conveyorizfed
$4,160
$256
$1,100
$27,000
$758
$325
$0
$1,670
$1,050
$7,190
$7,710
$1,740
$288
$385
$53,700
$0.15
Cost Category
Capital Cost
Material Cost
Utility Cost
Wastewater Cost
Production
Cost
Maintenance
Cost
Cost Components
Primary Equipment
Installation
Facility
Chemicals
Water
Electricity
Natural Gas
Wastewater Discharge
Transportation of Material
Labor for Line Operation
Tank Cleanup
Bath Setup
Sampling and Testing
Filter Replacement
Total Cost
Unit Cost ($/ssf)
Tin-Palladium,
conveyorjzed
$1,280
$205
$1,490
$25,500
$317
$468
$0
$754
$537
$5,230
$3,950
$891
$493
$332
$41,400
$0.12
Tin-Palladium,
non-conveyorized
$4,760
$381
$1,910
$22,300
$1,010
$635
$0
$2,340
$455
$10,700
$3,350
$755
$916
$616
$50,100
$0.14
7-14
-------
7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
Chemical cost was the single largest component cost for nine of the ten processes.
Equipment cost was the largest cost for the non-conveyorized electroless copper process. Three
separate sensitivity analyses of the results indicated that chemical cost, production labor cost, and
equipment cost have the greatest effect on the overall cost results.
Regulatory Status
Discharges of MHC chemicals may be restricted by federal, state or local air, water or
solid waste regulations, and releases may be reportable under the federal Toxic Release
Inventory program. Federal environmental regulations were reviewed to determine the federal
regulatory status of MHC chemicals.11 Table 7.7 lists the number of chemicals used in an MHC
technology with federal environmental regulations restricting or requiring reporting of their
discharges. Different chemical suppliers of a technology do not always use the same chemicals
in their particular product lines. Thus, all of these chemicals may not be present in any one
product line.
International Information
The total world market for PWBs is approximately $21 billion (EPA, 1995). The U.S.
and Japan are the leading suppliers of PWBs, but Hong Kong, Singapore, Taiwan, and Korea are
increasing their market share. Information on the use of MHC technologies worldwide was
collected to assess whether global trends affect the competitiveness of an alternative.
The alternatives to the traditional electroless copper MHC process are in use in many
countries. Most of the suppliers of these alternatives have manufacturing facilities located in
countries to which they sell. Several suppliers indicated the market shares of the alternatives are
increasing internationally quicker than they are increasing in the U.S. The cost-effectiveness of
an alternative has been the main driver causing PWB manufacturers abroad to switch from an
electroless copper process to one of the newer alternatives. In addition to the increased capacity
and decreased labor requirements of some of the MHC alternatives over the electroless copper
process, environmental concerns also affected the process choice. For instance, the rate at which
an alternative consumes water and the presence or absence of strictly regulated chemicals are two
factors which have a substantial effect on the cost-effectiveness of MHC alternatives abroad.
While environmental regulations do not seem to be the primary forces leading toward the
adoption of the newer alternatives, it appears that the companies that supply these alternatives are
taking environmental regulations and concerns into consideration when designing alternatives.
11 In some cases, state or local requirements may be more restrictive than federal requirements. However,
due to resource limitations, only federal regulations were reviewed.
7-15
-------
7.1 RISK. COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
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7-16
-------
7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
7.1.3 Resource Conservation Summary
Resources typically consumed by the operation of the MHC process include water used
for rinsing panels, process chemicals used on the process line, energy used to heat process baths
and power equipment, and wastewater treatment chemicals. A quantitative analysis of the energy
and water consumption rates of the MHC process alternatives was performed to determine if
implementing an alternative to the baseline process would reduce consumption of these resources
during the manufacturing process. A quantitative analysis of both process chemical and
treatment chemical consumption could not be performed due to the variability of factors that
affect the consumption of these resources. Section 5.1 discusses the role the MHC process has in
the consumption of these resources and the factors affecting the consumption rates.
The relative water and energy consumption rates of the MHC process alternatives were
determined as follows:
• The daily water consumption rate and hourly energy consumption rate of each alternative
were determined based on data collected from the BPC Workplace Practices
Questionnaire.
• The operating time required to produce 350,000 ssf of PWB was determined using
computer simulations models of each of the alternatives.
• The water and energy consumption rates per ssf of PWB were calculated based on the
consumption rates and operating times.
Table 7.8 presents the results of these analyses.
Table 7.8 Energy and Water Consumption Rates of MHC Alternatives
Process Type
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Water
Consumption
(gal/ssf)
11.7
1.15
1.29
0.73
0.45
3.74
1.35
1.13
1.80
0.57
Energy
Consumption
(Bt«/ssf)
573
138
514
94.7
213
270
66.9
148
131
96.4
The energy consumption rates ranged from 66.9 Btu/ssf for the non-conveyorized
organic-palladium process to 573 Btu/ssf for the non-conveyorized electroless copper process.
The results indicate that all of the MHC alternatives are more energy efficient than the baseline
process. They also indicate that for alternatives with both types of automation, the conveyorized
-------
7.1 RISK, COMPETITIVENESS, AND CONSERVATION DATA SUMMARY
version of the process is typically more energy efficient, with the notable exception of the
organic-palladium process.
An analysis of the impacts directly resulting from the consumption of energy by the
MHC process showed that the generation of the required energy has environmental impacts.
Pollutants released to air, water, and soil can result in damage to both human health and the
environment. The consumption of natural gas tends to result in releases to the air which
contribute to odor, smog, and global warming, while the generation of electricity can result in
pollutant releases to all media with a wide range of possible affects. Since all of the MHC
alternatives consume less energy than the baseline, they all result in less pollutant releases to the
environment.
Water consumption rates ranged from 0.45 gal/ssf for the graphite process to 11.7 gal/ssf
for the non-conveyorized electroless copper process. In addition, results indicate that all of the
alternatives consume significantly less water than the baseline process. Conveyorized processes
were found to consume less water than non-conveyorized versions of the same process.
The rate of water consumption is directly related to the rate of wastewater generation.
Most PWB facilities discharge process rinse water to an on-site wastewater treatment facility for
pretreatment prior to discharge to a publicly-owned treatment works (POTW). A pollution
prevention analysis identified a number of pollution prevention techniques that can be used to
reduce rinse water consumption. These include use of more efficient rinse configurations, use of
flow control technologies, and use of electronic sensors to monitor contaminant concentrations in
rinse water. Further discussion of these and other pollution prevention techniques can be found
in the Pollution Prevention section of this CTSA (Section 6.1) and in PWB Project Case Study 1
(EPA, 1995).
7-18
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
7.2.1 Introduction to Social Benefits/Costs Assessment
Social benefits/costs analysis12 is a tool used by policy makers to systematically evaluate
the impacts to all of society resulting from individual decisions. The decision evaluated in this
analysis is the choice of an MHC technology. PWB manufacturers have a number of criteria
they may use to assess which MHC technology they will use. For example, a PWB manufacturer
might ask what impact their choice of an MHC alternative might have on operating costs,
compliance costs, liability costs, and insurance premiums. This business planning process is
unlike social benefit/cost analysis, however, because it approaches the comparison from the
standpoint of the individual manufacturer and not from the standpoint of society as a whole.
A social benefits/costs analysis seeks to compare the benefits and costs of a given action,
while considering both the private and external costs and benefits.13 Therefore, the analysis will
consider both the impact of the alternative MHC processes on the manufacturer itself (private
costs and benefits) and the impact the choice of an alternative has on external costs and benefits,
such as reductions in environmental damage and reductions in the risk of illness for the general
public. External costs are not borne by the manufacturer, rather they are the true costs to society.
Table 7.9 defines a number of terms used in benefit/cost assessment, including external costs and
external benefits.
12 The term "analysis" is used here to refer to a more quantitative analysis of social benefits and costs,
where a monetary value is placed on the benefits and costs to society of individual decisions. Examples of
quantitative benefits/costs analyses are the regulatory impact analyses done by EPA when developing federal
environmental regulations. The term "assessment" is used here to refer to a more qualitative examination of social
benefits and costs. The evaluation performed in the CTSA process is more correctly termed an assessment because
many of the social benefits and costs of MHC technologies are identified, but not monetized.
13 Private costs typically include any direct costs incurred by the decision-maker and are generally
reflected in the manufacturer's balance sheet. In contrast, external costs are incurred by parties other than the
primary participants to the transaction. Economists distinguish between private and external costs because each will
affect the decision-maker differently. Although external costs are real costs to some members of society, they are
not incurred by the decision-maker and firms do not normally take them into account when making decisions. A
common example of these "externalities" is the electric utility whose emissions are reducing crop yields for the
farmer operating downwind. The external costs experienced by the farmer in the form of reduced crop yields are
not considered by the utility when making decisions regarding electricity production. The farmer's losses do not
appear on the utility's balance sheet.
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Table 7.9 Glossary of Benefits/Costs Analysis Terms
Term
Exposed
Population
Exposed Worker
Population
Externality
External Benefits
External Costs
Human Health
Benefits
Human Health
Costs
Illness
Costs
Indirect Medical
Costs
Definition
The estimated number of people from the general public or a specific population
group who are exposed to a chemical through wide dispersion of a chemical in the
environment (e.g., DDT). A specific population group could be exposed to a
chemical due to its physical proximity to a manufacturing facility (e.g., residents
who live near a facility using a chemical), use of the chemical or a product
containing a chemical, or through other means.
The estimated number of employees in an industry exposed to the chemical,
process, and/or technology under consideration. This number may be based on
market share data as well as estimations of the number of facilities and the number
of employees in each facility associated with the chemical, process, and/or
technology under consideration.
A cost or benefit that involves a third party who is not a part of a market
transaction; "a direct effect on another's profit or welfare arising as an incidental
by-product of some other person's or firm's legitimate activity" (Mishan, 1976).
The term "externality" is a general term which can refer to either external benefits
or external costs.
A positive effect on a third party who is not a part of a market transaction. For
example, if an educational program results in behavioral changes which reduce the
exposure of a population group to a disease, then an external benefit is experienced
by those members of the group who did not participate in the educational program.
For the example of nonsmokers exposed to second-hand smoke, an external benefit
can be said to result when smokers are removed from situations in which they
expose nonsmokers to tobacco smoke.
A negative effect on a third party who is not part of a market transaction. For
example, if a steel mill emits waste into a river which poisons the fish in a nearby
fishery, the fishery experiences an external cost as a consequence of the steel
production. Another example of an external cost is the effect of second-hand
smoke on nonsmokers.
Reduced health risks to workers in an industry or business as well as to the general
public as a result of switching to less toxic or less hazardous chemicals, processes,
and/or technologies. An example would be switching to a less volatile organic
compound, lessening worker inhalation exposures as well as decreasing the
formation of photochemical smog in the ambient air.
The cost of adverse human health effects associated with production, consumption,
and disposal of a firm's product. An example is respiratory effects from stack
emissions, which can be quantified by analyzing the resulting costs of health care
and the reduction in life expectancy, as well as the lost wages as a result of being
unable to work.
A financial term referring to the liability and health care insurance costs a company
must pay to protect itself against injury or disability to its workers or other affected
individuals. These costs are known as illness benefits to the affected individual.
Indirect medical costs associated with a disease or medical condition resulting from
exposure to a chemical or product. Examples would be the decreased productivity
of patients suffering a disability or death and the value of pain and suffering borne
by the afflicted individual and/or family and friends.
7-20
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Term
Definition
}rivate
(Internalized)
Costs
The direct costs incurred by industry or consumers in the marketplace. Examples
include a firm's cost of raw materials and labor, a firm's costs of complying with
environmental regulations, or the cost to a consumer of purchasing a product.
Social
:osts
The total cost of an activity that is imposed on society. Social costs are the sum of
the private costs and the external costs. Therefore, in the example of the steel mill,
social costs of steel production are the sum of all private costs (e.g., raw material
and labor costs) and the sum of all external costs (e.g., the costs associated with the
poisoned fish).
Social
Benefits
The total benefit of an activity that society receives, i.e., the sum of the private
benefits and the external benefits. For example, if a new product yields pollution
prevention opportunities (e.g., reduced waste in production or consumption of the
product), then the total benefit to society of the new product is the sum of the
private benefit (value of the product that is reflected in the marketplace) and the
external benefit (benefit society receives from reduced waste).
Willingness-to-Pay
Estimates used in benefits valuation are intended to encompass the full value of
avoiding a health or environmental effect. For human health effects, the
components of willingness-to-pay include the value of avoiding pain and suffering,
impacts on the quality of life, costs of medical treatment, loss of income, and, in
the case of mortality, the value of life.
Private benefits of the alternative MHC processes may include increased profits resulting
from improved worker productivity and company image, a reduction in energy use, or reduced
property and health insurance costs due to the use of less hazardous chemicals. External benefits
may include a reduction in pollutants emitted to the environment or reduced use of natural
resources. Costs of the alternative MHC processes may include private costs such as changes in
operating expenses and external costs such as an increase in human health risks and ecological
damage. Several of the benefit categories considered in this assessment share elements of both
private and external costs and benefits. For example, use of an alternative may result in natural
resource savings. Such a benefit may result in private benefits in the form of reduced water
usage and a resultant reduction in payments for water as well as external benefits in the form of
reduced consumption of shared resources.
7.2.2 Benefits/Costs Methodology and Data Availability
The methodology for conducting a social benefits/costs assessment can be broken down
into four general steps: 1) obtain information on the relative human and environmental risk,
performance, cost, process safety hazards, and energy and natural resource requirements of the
baseline and the alternatives; 2) construct matrices of the data collected; 3) when possible,
monetize the values presented within the matrices; and 4) compare the data generated for the
alternative and the baseline in order to produce an estimate of net social benefits. Section 7.1
presented the results of the first task by summarizing risk, competitiveness, and conservation
information for the baseline and alternative MHC technologies. Section 7.2.3 presents matrices
of private benefits and costs data, while Section 7.2.4 presents information relevant to external
benefits and costs. Section 7.2.5 presents the private and external benefits and costs together to
produce an estimate of net social benefits.
—
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Ideally, the analysis would quantify the social benefits and costs of using the alternative
and baseline MHC technologies, allowing identification of the technology whose use results in
the largest net social benefit. This is particularly true for national estimates of net social benefits
or costs. However, because of resource and data limitations and because individual users of this
CTSA will need to apply results to their own particular situations, the analysis presents a
qualitative description of the risks and other external effects associated with each substitute
technology compared to the baseline. Benefits derived from a reduction in risk are described and
discussed, but not quantified. Nonetheless, the information presented can be very useful in the
decision-making process. A few examples are provided to qualitatively illustrate some of the
benefit considerations. Personnel in each individual facility will need to examine the
information presented, weigh each piece according to facility and community characteristics, and
develop an independent choice.
7.2.3 Private Benefits and Costs
While it is difficult to obtain an overall number to express the private benefits and costs
of alternative MHC processes, some data were quantifiable. For example, the cost analysis
estimated the average manufacturing costs of the MHC technologies, including the average
capital costs (primary equipment, installation, and facility cost), materials costs (limited to
chemical costs), utility costs (water, electricity, and natural gas costs), wastewater costs (limited
to wastewater discharge cost), production cost (production labor and chemical transport costs),
and maintenance costs (tank cleanup, bath setup, sampling and analysis, and filter replacement
costs). Other cost components may contribute significantly to overall manufacturing costs, but
were not quantified because they could not be reliably estimated. These include wastewater
treatment cost, sludge recycling and disposal cost, other solid waste disposal costs, and quality
costs.
Differences in the manufacturing costs estimated in the cost analysis are summarized
below. However, in order to determine the overall private benefit/cost comparison, a qualitative
discussion of the data is also necessary. Following the discussion of manufacturing costs are
discussions of private costs associated with occupational and population health risks and other
private costs or benefits that could not be monetized but are important to the decision-making
process.
Manufacturing Costs
Table 7.10 presents the percent change in manufacturing costs for the MHC alternatives
as compared to the baseline. Only costs that were quantified in the cost analysis are presented.
All of the alternatives result in cost savings in the form of lower total costs; most of the
alternatives result in cost savings in almost every cost category. In addition, the Performance
Demonstration determined that each alternative has the capability to achieve comparable levels
of performance to electroless copper, thus quality costs are considered equal among the
alternatives. This is important to consider in a benefits/costs analysis since changes in
performance necessarily result in changed costs in the market. This is not the case in this
assessment since all alternatives yield comparable performance results.
7-22
-------
7,2 SOCIAL BENEFITS/COSTS ASSESSMENT
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7-23
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Occupational Health Risks
Reduced risks to workers can be considered both a private and external benefit. Private
worker benefits include reductions in worker sick days and reductions in health insurance costs
to the PWB manufacturer. External worker benefits include reductions in medical costs to
workers in addition to reductions in pain and suffering associated with work-related illness.
External benefits from reduced risk to workers are discussed in more detail in Section 7.2.4.
Health risks to workers were estimated for inhalation exposure to vapors and aerosols
from MHC baths and for dermal exposure to MHC bath chemicals. Inhalation exposure
estimates are based on the assumptions that emissions to indoor air from conveyorized lines are
negligible, that the air in the process room is completely mixed and chemical concentrations are
constant over time, and that no vapor control devices (e.g., bath covers) are used in non-
conveyorized lines. Dermal exposure estimates are based on the assumption that workers do not
wear gloves and that all non-conveyorized lines are operated by manual hoist. Dermal exposure
to workers on non-conveyorized lines could occur from routine line operation and maintenance
(i.e., bath replacement, filter replacement, etc.). Dermal exposure to workers on conveyorized
lines was assumed to occur from bath maintenance alone. Worker dermal exposure to all MHC
technologies can be easily minimized by using proper protective equipment such as gloves
during MHC line operation and maintenance. In addition, many PWB manufacturers report that
their employees routinely wear gloves in the process area. Nonetheless, risk from dermal contact
was estimated assuming workers do not wear gloves to account for those workers who do not
wear proper personal protective equipment.
Because some parts of the exposure assessment for both inhalation and dermal exposures
qualify as "what-if' descriptors,14 the entire assessment should be considered "what-if." Table
7.11 summarizes the number of chemicals of concern for the exposure pathways evaluated and
lists the number of suspected carcinogens in each technology.
Based on the results of the risk characterization, it appears that alternatives to the non-
conveyorized electroless copper process have private benefits due to reduced occupational risks.
However, there are also occupational inhalation risk concerns for some chemicals in the non-
formaldehyde electroless copper and tin-palladium non-conveyorized processes. In addition,
there are occupational dermal exposure risk concerns for some chemicals in the conveyorized
electroless copper process, the non-conveyorized non-formaldehyde electroless copper, and the
tin-palladium and organic palladium processes with conveyorized or non-conveyorized
equipment. Finally, occupational health risks could not be quantified for one or more of the
chemicals used in each of the MHC technologies. This is due to the fact that proprietary
chemicals in the baths are not included15 for chemical products submitted by Atotech (except one
14 A "what-if' risk descriptor represents an exposure estimate based on postulated questions, making
assumptions based on limited data where the distribution is unknown.
15 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project for evaluation in the risk characterization. Atotech provided information on one
proprietary chemical ingredient. Risk results for proprietary chemicals in chemical products but not chemical
identities or concentrations, are included in this CTSA.
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
proprietary chemical in one of Atotech's technologies), Enthone-OME, MacDermid and Shipley,
and to a lack of toxicity or chemical property data for some chemicals known to be present in the
baths.
Table 7.11 Summary of Occupational Hazards, Exposures, and Risks of Potential Concern
MHC Technology
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
No. of Chemicals of
Concern by Pathway"
Inhalation
10
0
0
0
0
1
0
0
2
0
Dermal
8
8
0
0
0
2
1
1
5
5
No. of
Suspected
Carcinogens
5b
5b
1
0
2°
0
0
0
0
0
1NU11IUCJ.
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Public Health Risks
In addition to worker exposure, members of the general public may be exposed to MHC
chemicals due to their close physical proximity to a PWB plant or due to the wide dispersion of
chemicals. Reduced public health risks can also be considered both a private and external
benefit. Private benefits include reductions in potential liability costs; external benefits include
reductions in medical costs. External benefits from reduced public health risk are discussed in
more detail in Section 7.2.4.
Public health risk was estimated for inhalation exposure only for the general populace
living near a facility. Environmental releases and risk from exposure to contaminated surface
water were not quantified due to a lack of data; chemical constituents and concentrations in
wastewater could not be adequately characterized. Public health risk estimates are based on the
assumption that emissions from both conveyorized and non-conveyorized process configurations
are steady-state and vented to the outside. Risk was not characterized for short-term exposures to
high levels of hazardous chemicals when there is a spill, fire, or other periodic release.
The risk indicators for ambient exposures to humans, although limited to airborne
releases, indicate low concern from all MHC technologies for nearby residents. The estimated
upper bound excess individual cancer risk for nearby residents exposed to emissions from the
non-conveyorized electroless copper process ranged from values approaching zero to 1 x 10~7
(one in ten million) for formaldehyde, and from approaching zero to 1 x 10"11 (one in 100 billion)
for the alkyl oxide. The estimated cancer risk values for the conveyorized electroless copper
process ranged from values approaching zero to 3 x 10'7 (one in three million) for formaldehyde,
and from approaching zero to 3 x 10"11 (one in 33 billion) for the alkyl oxide. The estimated
cancer risk for nearby residents exposed to emissions from the conveyorized graphite process
ranged from values approaching zero to 9 x 10'11 (one in 11 billion) for the alkyl oxide. The risk
characterization for ambient exposure to other MHC chemicals also indicated low concern from
the estimated air concentrations for chronic non-cancer effects.
These results suggest little change in public health risks and, thus, private benefits or
costs if a facility switched from the baseline to an MHC alternative. However, it is important to
note that it was not within the scope of this comparison to assess all community health risks.
The risk characterization did not address all types of exposures that could occur from MHC
processes or the PWB industry, including short-term or long-term exposures from sudden
releases due to spills, fires, or periodic releases.
Ecological Risks
MHC chemicals are potentially damaging to terrestrial and aquatic ecosystems, resulting
in both private costs borne by the manufacturers and external costs borne by society. Private
costs could include increased liability costs while external costs could include loss of ecosystem
diversity and reductions in the recreational value of streams and rivers. The CTSA evaluated the
ecological risks of the baseline and alternatives in terms of aquatic toxicity hazards. Aquatic risk
could not be estimated because chemical concentrations in MHC line effluents and streams were
not available and could not be estimated. It is not possible to reliably estimate concentrations
7-26
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
only from the MHC process since most PWB manufacturers combine MHC effluents with
effluents from other process lines.
Table 7.12 presents the number of chemicals in each technology with a high aquatic
hazard concern level. There are well documented copper pollution problems associated with
discharges to surface waters and many of the MHC alternatives contain copper compounds. The
lowest CC for an MHC chemical is for copper sulfate, which is found in five of the MHC
technology categories: electroless copper, carbon, graphite, non-formaldehyde electroless
copper, and tin-palladium. Bath concentrations of copper sulfate vary, ranging from a high of
22 g/1 for the non-formaldehyde electroless copper technology to a low of 0.2 g/1 in one of the
tin-palladium processes (and, based on MSDS data, not present in the conductive ink, conductive
polymer, or organic-palladium processes). Because the concentration of copper sulfate in
different MHC line effluents is not known, the benefits or costs of using one of these MHC
alternatives cannot be assessed. For example, the non-formaldehyde electroless copper process
has a higher bath concentration of copper sulfate than the baseline; however, because the non-
formaldehyde electroless copper process does not contain the chelator EDTA, more copper may
be removed during wastewater treatment.
Table 7.12 Number of Chemicals with High Aquatic Hazard Concern Level
MHC Technology
Electroless Copper
Carbon
Conductive Ink
Conductive Polymer
Graphite
Non-Formaldehyde Electroless Copper
Organic-Palladium
Tin-Palladium
No. of Chemicals
9
2
2
0
3
3
2
9
Plant-Wide Benefits or Costs
The CTSA did not determine the PWB plant-wide benefits or costs that could occur from
implementing an alternative to the baseline MHC technology. However, a recent study of the
Davila International PWB plant in Mountain View, California, identified a number of changes to
the PWB manufacturing process that were only possible when an alternative to electroless copper
was installed. These changes reduced copper pollution and water use, resulting in cost savings.
A companion document to this publication, Implementing Cleaner Technologies in the Printed
Wiring Board Industry: Making Holes Conductive (EPA, 1997), describes some of the systems
benefits that can occur from implementing an MHC technology.
Improvements in the efficiency of the overall system not only provide private benefits,
but also social benefits.
In addition, the baseline MHC process is a production bottleneck in many shops, but the
alternative MHC technologies have substantially improved production rates. Thus, switching to
-------
7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
an alternative improves the competitiveness of a PWB manufacturer by enabling the same
number of boards to be produced faster or even enabling an increase in overall production
capacity. However, the increased productivity could have social costs if increased production
rates cause increased pollution rates in other process steps. Greater production rates in all the
processes should be coupled with pollution prevention measures.
Another cost could be incurred if increased production results in increased amounts of
scrap board. The Performance Demonstration determined that all of the alternatives have the
potential to perform as well as electroless copper if operated properly. However, vendors and
manufacturers who have implemented the alternatives stress the importance of taking a "whole-
process" view of new MHC technology installation. Process changes upstream or downstream
may be necessary to optimize alternative MHC processes (EPA, 1997). This is also important
from a societal perspective because an increase in scrap boards can increase pollution generation
off-site. In particular, citizens groups are concerned about potential dioxin emissions from the
off-site process of secondary metal smelting which recycles scrap boards (Smith and Karras,
1997).
Other Private. Benefits and Costs
Table 7.13 gives additional examples of private costs and benefits that could not be
quantified. These include wastewater treatment, solid waste disposal, compliance, liability,
insurance and worker illness costs, and improvements in company image that accrue from
implementing a substitute. Some of these were mentioned above, but are included in the table
due to their importance to overall benefits and costs.
7.2.4 External Benefits and Costs
External costs are those costs that are not taken into account in the manufacturer's pricing
and manufacturing decisions. These costs are commonly referred to as "externalities" and are
costs that are borne by society and not by the individuals who are part of a market transaction.
These costs can result from a number of different avenues in the manufacturing process. For
example, if a manufacturer uses a large quantity of a non-renewable resource during the
manufacturing process, society will eventually bear the costs for the depletion of this natural
resource. Another example of an external cost is an increase in population health effects
resulting from the emission of chemicals from a manufacturing facility. The manufacturer does
not pay for any illnesses that occur outside the plant that result from air emissions. Society must
bear these costs in the form of medical care payments or higher insurance premiums.
Conversely, external benefits are those that do not benefit the manufacturer directly. For
example, an alternative that uses less water results in both private and external benefits. The
manufacturer pays less for water; society in general benefits from less use of a scarce resource.
This type of example is why particular aspects of the MHC process are discussed in terms of
both private benefits and costs and external benefits and costs.
7-28
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Table 7.13 Examples of Private Costs and Benefits Not Quantified
Category
Description of Potential Costs or Benefits
Wastewater
Treatment
Solid Waste
Disposal
Alternatives to the baseline MHC technology may provide cost savings by
reducing the quantity and improving the treatability of process wastewaters. In
turn, these cost savings can enable the implementation of other pollution
prevention measures. Alternatives to the baseline process use less rinse water and,
consequently, produce less wastewater. hi addition, the elimination of the chelator
EDTA found in electroless copper processes simplifies the removal of heavy metal
ions by precipitation. However, other processes may contain complexing agents
that form bonds with metal ions, also making them difficult to remove. For
xample, the graphite technology contains the complexing agent ammonia. All of
these factors—reducing the quantity of wastewater, reducing the amount of
chelated or complexed metals in wastewater effluents, and enabling pollution
prevention measures—provide social benefits as well as private benefits.
All of the alternatives result in the generation of sludge, off-specification PWBs,
and other solid wastes, such as spent bath filters. These waste streams must be
recycled or disposed of, some of them as hazardous waste. For example, many
PWB manufacturers send sludges to a recycler to reclaim metals in the sludge.
Sludges that cannot be effectively recycled will most likely have to be landfilled.
It is likely that the manufacturer will incur costs in order to recycle or landfill these
sludges and other solid wastes, however these costs were not quantified. Three
categories of MHC technologies generate RCRA-listed wastes, including
electroless copper, conductive ink, and tin-palladium. However, other
technologies may generate wastes considered hazardous because they exhibit
certain characteristics. In addition, most facilities combine wastewater from
various process lines prior to on-site treatment, including wastewater from
electroplating operations. Wastewater treatment sludge from copper electroplating
operations is a RCRA F006 hazardous waste. Reducing the volume and toxicity of
solid waste also provides social benefits.
Compliance
Costs
The cost of complying with all environmental and safety regulations affecting the
MHC process line was not quantified. However, chemicals and wastes from the
MHC alternatives are subject to fewer overall federal environmental regulations
tiian the baseline, suggesting that implementing an alternative could potentially
reduce compliance costs. It is more difficult to assess the relative cost of
complying with OSHA requirements, because the alternatives pose similar
occupational safety hazards (although non-automated, non-conveyorized
equipment may pose less overall process hazards than working with mechanized
equipment).
Liability, Insurance,
and Worker Illness
Costs
Based on the results of the risk characterization, it appears that alternatives to the
baseline process pose lower overall risk to human health and the environment.
Implementing an alternative could cause private benefits in the form of lower
liability and insurance cost and increased employee productivity from decreases in
incidences of illness. Clearly, alternatives with reduced risk also provide social
benefits (discussed in Section 7.2.4). ^^^^
Company
Image
Many businesses are finding that using cleaner technologies results in less tangible
benefits, such as an improved company image and improved community relations.
While it is difficult to put a monetary value on these benefits, they should be
considered in the decision-making process.
7-29
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
The potential external benefits associated with the use of an MHC alternative include:
reduced health risk for workers and the general public, reduced ecological risk, and reduced use
of energy and natural resources. Another potential externality is the influence a technology
choice has on the number of PWB plant jobs in a community. Each of these is discussed in turn
below.
Occupational Health Risks
Section 7.2.3 discussed risk characterization results for occupational exposures. Based on
the results of the risk characterization, it appears that alternatives to the non-conveyorized
electroless copper process have private benefits due to reduced occupational risks. However,
there are also occupational inhalation risk concerns for some chemicals in the non-formaldehyde
electroless copper and tin-palladium non-conveyorized processes. In addition, there are
occupational dermal exposure risk concerns for some chemicals in the conveyorized electroless
copper, the non-conveyorized non-formaldehyde electroless copper, and organic-palladium and
tin-palladium processes with conveyorized or non-conveyorized equipment. Finally,
occupational health risks could not be quantified for one or more of the chemicals used in each of
the MHC technologies. This is due to the fact that proprietary chemicals in the baths were not
identified by some suppliers17 and to missing toxicity or chemical property data for some
chemicals known to occur in the baths.
Reduced occupational risks provide significant private as well as social benefits. Private
benefits can include reduced insurance and liability costs, which may be readily quantifiable for
an individual manufacturer. External benefits are not as easily quantifiable. They may result
from the workers themselves having reduced costs such as decreased insurance premiums or
medical payments or society having reduced costs based on the structure of the insurance
industry.
Data exist on the cost of avoiding or mitigating certain illnesses that are linked to
exposures to MHC chemicals. These cost estimates can serve as indicators of the potential
benefits associated with switching to technologies using less toxic chemicals or with reduced
exposures. Table 7.14 lists potential health effects associated with MHC chemicals of concern.
It is important to note that, except for cancer risk from formaldehyde, the risk characterization
did not link exposures of concern with particular adverse health outcomes or with the number of
incidences of adverse health outcomes.18 Thus, the net benefit of illnesses avoided by switching
to an MHC alternative cannot be calculated.
17 Electrochemicals, LeaRonal, and Solution Technology Systems provided information on proprietary
chemical ingredients to the project for evaluation in the risk characterization. Atotech provided information on one
proprietary chemical used in the product line. Enthone-OMI, MacDermid, and Shipley declined to provide
proprietary chemical information. Risk results for proprietary chemicals, as available, but not chemical identities or
concentrations, are included in this CTSA.
18 Cancer risk from formaldehyde exposure was expressed as a probability, but the exposure assessment
did not determine the size of the potentially exposed population (e.g., number of MHC line operators and others
working in the process area). This information would be necessary to estimate the number of illnesses avoided by
switching to an alternative from the baseline.
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Table 7.14 Potential Health Effects Associated with MHC Chemicals of Concern
Chemical of
Concern
Alkene Diol
Copper Chloride
Ethanolamine
2-Ethoxyethanol
Ethylene Glycol
Fluoroboric Acid
Alternatives with
Exposure Levels of
Concetti
Electroless Copper
Electroless Copper
Electroless Copper,
Tin-Palladium
Electroless Copper
Electroless Copper
Electroless Copper,
Tin-Palladiurri
Pathway
of
Concetti*
inhalation
inhalation
dermal
inhalation
inhalation
inhalation
dermal
Potential Health Effects
Exposure to low levels may result in irritation of
the throat and upper respiratory tract.
Long-term exposure to copper dust can irritate
nose, mouth, eyes and cause dizziness. Long-term
exposure to high levels of copper may cause liver
damage. Copper is not known to cause cancer.
The seriousness of the effects of copper can be
expected to increase with both level and length of
exposure.
No data were located for health effects from dermal
exposure in humans.
Ethanolamine is a strong irritant Animal studies
showed that the chemical is an irritant to the
respiratory tract, eyes, and skin. No data were
located for inhalation exposure in humans.
hi animal studies 2-ethoxyethanol caused harmful
blood effects, including destruction of red blood
cells and releases of hemoglobin (hemolysis), and
male reproductive effects at high exposure levels.
The seriousness of the effects of the chemical can
be expected to increase with both level and length
of exposure. No data were located for inhalation
exposure in humans.
hi humans, low levels of vapors produce throat and
upper respiratory irritation. When ethylene glycol
breaks down in the body, it forms chemicals that
crystallize and that can collect in the body and
prevent kidneys from working. The seriousness of
the effects of the chemical can be expected to
increase with both level and length of exposure.
Fluoroboric acid in humans produces strong caustic
effects leading to structural damage to skin and
eyes.
7-31
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Chemical of
Concern
formaldehyde
Vlethanol
Nitrogen
Heterocycle
Palladium
Palladium
Chloride
Palladium Salt
Sodium
Carboxylate
Sodium Chlorite
Stannous
Chloride
Alternatives with
Exposure levels of
Coiicern
Jlectroless Copper
Electroless Copper
Electroless Copper
ilectroless Copper,
Tin-Palladium
Tin-Palladium
Organic-Palladium
Electroless Copper
Electroless Copper,
Non-Formaldehyde
Electroless Copper
Electroless Copper,
Non-Formaldehyde
Electroless Copper,
Tin-Palladium
Pathway
of
Concert!"
inhalation
dermal
inhalation
dermal
dermal
dermal
dermal
dermal
dermal
dermal
Potential Health Effects
EPA has classified formaldehyde as a probable
luman carcinogen (EPA Group Bl). Inhalation
exposure to formaldehyde in animals produces
nasal cancer at low levels. In humans, exposure to
brmaldehyde at low levels in air produces skin
irritation and throat and upper respiratory irritation.
The seriousness of these effects can be expected to
increase with both level and length of exposure.
n humans, exposure to formaldehyde at low levels
in air produces skin irritation. The seriousness of
these effects can be expected to increase with both
level and length of exposure.
Long-term exposure to methanol vapors can cause
leadache, irritated eyes and dizziness at high
levels. No harmful effects were seen when
monkeys were exposed to highly concentrated
vapors of methanol. When methanol breaks down
in the tissues, it forms chemicals that can collect in
the tissues or blood and lead to changes in the
interior of the eye causing blindness.
No data were located for health effects from dermal
exposure in humans.
No specific information was located for dermal
exposure of palladium in humans.
Long-term dermal exposure to palladium chloride
in humans produces contact dermatitis.
Exposure may result in skin irritation and
sensitivity.
No data were located for health effects from dermal
exposure in humans.
No specific information was located for health
effects from dermal exposure to sodium chlorite in
humans. Animal studies showed that the chemical
produces moderate irritation of skin and eyes.
Mild irritation of the skin and mucous membrane
has been shown from inorganic tin salts.
However, no specific information was located for
dermal exposure to stannous chloride in humans.
Stannous chloride is only expected to be harmful at
high doses; it is poorly absorbed and enters and
leaves the body rapidly.
7-32
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Chemical of
Concern
Sulfuric Acid
Tin Salt
Alternatives with
Exposure kevels of
Concern
Electroless Copper,
Non-Formaldehyde
Electroless Copper,
Tin-Palladium
Electroless Copper
Pathway
of
Concern*
inhalation
dermal
Potential Health Effects
Sulfuric acid is a very strong acid and can cause
structural damage to skin and eyes. Humans
exposed to sulfuric acid mist at low levels in air
experience a choking sensation and irritation of
lower respiratory passages.
No data were located for health effects from dermal
exposure in humans. Inorganic tin compounds may
irritate the eyes, nose, throat, and skin.
Inhalation concerns only apply to non-conveyorized processes. Dermal concerns may apply to non-conveyorized
and/or conveyorized processes (see Table 7.3).
Health endpoints potentially associated with MHC chemicals of concern include: nasal
cancer (for formaldehyde), eye irritation, and headaches. The draft EPA publication, The
Medical Costs of Selected Illnesses Related to Pollutant Exposure (EPA, 1996), evaluates the
medical cost of some forms-of cancer, but not nasal cancer. Other publications have estimated
the economic costs associated with eye irritation and headaches. These data are discussed below.
Benefits of Avoiding Illnesses Potentially Linked to MHC Chemical Exposure
This section presents estimates of the economic costs of some of the illnesses or
symptoms associated with exposure to MHC chemicals. To the extent that MHC chemicals are
not the only factor contributing toward the illnesses described, individual costs may overestimate
the potential benefits to society from substituting alternative MHC technologies for the baseline
electroless copper process. For example, other PWB manufacturing process steps may also
contribute toward adverse worker health effects. The following discussion focuses on the
external benefits of reductions in illness. However, private benefits may be accrued by PWB
manufacturers through increased worker productivity and a reduction in liability and health care
insurance costs. While reductions in insurance premiums as a result of pollution prevention are
not currently widespread, the opportunity exists for changes in the future.
Exposure to several of the chemicals of concern is associated with eye irritation. Other
potential health effects include headaches and dizziness. The economic literature provides
estimates of the costs associated with eye irritation and headaches. An analysis by Unsworth and
Neumann summarizes the existing literature on the costs of illness based on estimates of how
much an individual would be willing to pay to avoid certain acute effects for one symptom day
(Unsworth and Neumann, 1993). These estimates are based upon a survey approach designed to
elicit estimates of individual willingness-to-pay to avoid a single incidence and not the lifetime
costs of treating a disease. Table 7.15 presents a summary of the low, mid-range, and high
estimates of individual willingness-to-pay to avoid eye irritation and headaches. These estimates
provide an indication of the benefit per affected individual that would accrue to society if
switching to a substitute MHC technology reduced the incidence of these health endpoints.
7-33
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Table 7.15 Estimated Willingness-to-Pay to Avoid Morbidity Effects for
One Symptom Day (1995 dollars)
Health Endpoint
Eye Irritation8
Headache6
Low
$21
$2
Mid-Range
$21
$13
High
$46
$67
Tolley, G.S., et al. January 1986. Valuation ofReductiom in Human Health Symptoms and Risks. University of
Chicago. Final Report for the U.S. EPA. As cited in Unsworth, Robert E. and James E. Neumann, Industrial
Economics, Incorporated. Memorandum to Jim DeMocker, Office of Policy Analysis and Review. Review of
Existing Value of Morbidity Avoidance Estimates: Draft Valuation Document. September 30,1993.
* Dickie, M., et al. September 1987. Improving Accuracy andReducing Costs of'Environmental Benefit
Assessments. U.S. EPA, Washington, DC. Tolley, G.S., et al. Valuation of Reductions in Human Health Symptoms
andRisks. January 1986. University of Chicago. Final Report for the U.S. EPA. As cited in Unsworth, Robert E.
and James E. Neumann, Industrial Economics, Incorporated. Memorandum to Jim DeMocker, Office of Policy
Analysis and Review. Review of Existing Value of Morbidity Avoidance Estimates: Draft Valuation Document.
September 30,1993.
Public Health Risk
Section 7.2.3 discussed public health risks from MHC chemical exposure. The risk
characterization identified no concerns for the general public through ambient air exposure with
the possible exception of formaldehyde exposure from electroless copper processes. While the
study found little difference among the alternatives for those public health risks that were
assessed, it was not within the scope of this comparison to assess all community health risks.
Risk was not characterized for exposure via other pathways (e.g., drinking water, fish ingestion,
etc.) or short-term exposures to high levels of hazardous chemicals when there is a spill, fire, or
other periodic release.
Ecological Hazards
The CTSA evaluated the ecological risks of the baseline and alternatives in terms of
aquatic toxicity hazards. Aquatic risk could not be estimated because chemical concentrations in
MHC line effluents and streams were not available and could not be estimated. Reduced aquatic
hazards can provide significant external benefits, including improved ecosystem diversity,
unproved supplies for commercial fisheries, and improved recreational values of water resources.
There are well documented aquatic toxicity problems associated with copper discharges to
receiving waters, but this assessment was unable to determine the relative reduction in copper or
other toxic discharges from the baseline to the alternatives. Five processes contain copper
sulfate, the most toxic of the copper compounds found in MHC lines, and other processes contain
copper chloride. In order to evaluate the private and external benefits or costs of implementing
an alternative, PWB manufacturers should attempt to determine what the changes in their mass
loading of copper or other toxic discharges would be.19
19 Copper discharges are a particular problem because of the cumulative mass loadings of copper
discharges from a number of different industry sectors, including the PWB industry.
7-34
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
Energy and Natural Resources Consumption
Table 7.16 summarizes the water and energy consumption rates and percent changes in
consumption from the baseline to the MHC alternatives. All of the alternatives use substantially
less energy and water per ssf of PWB produced, with the exception of the carbon technology
which only has a slight decrease (< ten percent) in energy use from the baseline. While
manufacturers face direct costs from the use of energy and water in the manufacturing process,
society as a whole also experiences costs from this usage. For energy consumption, these types
of externalities can come in the form of increased emissions to the air either during the initial
manufacturing of the energy or the MHC processes themselves. These emissions include CO2,
SOX, NO2, CO, H2SO4, and particulate matter. Table 5.9 in the Energy Impacts section (Section
5.2) details the pollution resulting from the generation of energy consumed by MHC alternatives.
Environmental and human health concerns associated with these pollutants include global
warming, smog, acid rain, and health effects from toxic chemical exposure.
Table 7.16 Energy and Water Consumption of MHC Technologies
MHC Technology
Electroless Copper, non-conveyorized (BASELINE)
Electroless Copper, conveyorized
Carbon, conveyorized
Conductive Polymer, conveyorized
Graphite, conveyorized
Non-Formaldehyde Electroless Copper, non-conveyorized
Organic-Palladium, non-conveyorized
Organic-Palladium, conveyorized
Tin-Palladium, non-conveyorized
Tin-Palladium, conveyorized
Water
Consumption
gal/ssf
11.7
1.15
1.29
0.73
0.45
3.74
1.35
1.13
1.80
0.57
% change
-90
-89
-94
-96
-68
-88
-90
-85
-95
Energy
Consumption
Bto/ssf
573
138
514
94.7
213
270
66.9
148
131
96.4
% change
-76
-9.6
-83
-63
-53
-88
-74
-77
-83
In addition to increased pollution, the higher energy usage of the baseline also results in
external costs in the form of depletion of natural resources. Some form of raw resource is
required to make electricity, whether it be coal, natural gas or oil, and these resources are non-
renewable. While it is true that the price of the electricity to the manufacturer takes into account
the actual raw materials costs, the price of electricity does not take into account the depletion of
the natural resource base. As a result, eventually society will have to bear the costs for the
depletion of these natural resources.
The use of water and consequent generation of wastewater also results in external costs to
society. While the private costs of this water usage are included in the cost estimates in Table
7.10, the external costs are not. The private costs of water usage account for the actual quantities
of water used in the MHC process by each different technology. However, clean water is quickly
becoming a scarce resource, and activities that utilize water therefore impose external costs on
society. These costs can come in the form of higher water costs for the surrounding area or for
higher costs paid to treatment facilities to clean the water. These costs may also come in the
7-35
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
form of decreased water quality available to society. In fact, in Germany, PWB manufacturers
are required to use their wastewater at least three times before disposing of it because of the
scarcity of water.
Effects on Jobs
The results of the cost analysis suggest that alternative MHC technologies are generally
more efficient than the baseline process due to decreased cycle times. In addition, labor costs are
one of the biggest factors causing the alternatives to be cheaper. Neither the Cost Analysis nor
the CTSA analyzed the potential for job losses resulting from implementing an alternative.
However, if job losses were to occur, this could be a significant external cost to the community.
For example, in Silicon Valley, community groups are striving to retain clean, safe jobs through
directing cost savings to environmental improvements that create or retain jobs. While the
effects on jobs of wide-scale adoption of an alternative were not analyzed, anecdotal evidence
from facilities that have switched from the baseline suggests that jobs are not lost, but workers
are freed to work on other tasks (Keenan, 1997). In addition, one incentive for PWB
manufacturers to invest in the MHC alternatives is the increased production capacity of the
alternatives. Some PWB manufacturers who choose to purchase new capital-intensive
equipment are doing so because of growth, and would not be expected to lay off workers
(TCeenan, 1997).
Other External Benefits or Costs
In addition to the externalities discussed above, the baseline and MHC alternatives can
have other external benefits and costs. Many of these were discussed in Table 7.13 because
many factors share elements of both private and external benefits and costs. For example,
regulated chemicals result in a compliance cost to industry, but they also result in an enforcement
cost to society whose governments are responsible for ensuring environmental requirements are
met.
7.2.5 Summary of Benefits and Costs
The objective of a social benefits/costs assessment is to identify those technologies or
decisions that maximize net benefits. Ideally, the analysis would quantify the social benefits and
costs of using the alternative and baseline MHC technologies in terms of a single unit (e.g.,
dollars) and calculate the net benefits of using an alternative instead of the baseline technology.
Due to data limitations, however, this assessment presents a qualitative description of the
benefits and costs associated with each technology compared to the baseline. Table 7.17
compares some of the relative benefits and costs of each technology to the baseline, including
production costs, worker health risks, public health risks, aquatic toxicity concerns, water
consumption, and energy consumption. The effects on jobs of wide-scale adoption of an
alternative are not included in the table because the potential for job losses was not evaluated in
the CTSA. However, the results of the Cost Analysis suggest there are significantly reduced
labor requirements for the alternatives. Clearly, the loss of manufacturing jobs would be a
significant external cost to the community and should be considered by PWB manufacturers
when choosing an MHC technology.
7-36
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
it
O\
00
"S
N
1
13
&
§<
o
m
.S
E
eyori
Graphit
di
g
7-37
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7.2 SOCIAL BENEFITS/COSTS ASSESSMENT
While each alternative presents a mixture of private and external benefits and costs, it
appears that each of the alternatives have social benefits as compared to the baseline. In
addition, at least three of the alternatives appear to have social benefits over the baseline in every
category, but public health risk. These are the conveyorized conductive polymer process and
both conveyorized and non-conveyorized organic-palladium processes. However, the supplier of
these technologies has declined to provide complete information on proprietary chemical
ingredients for evaluation in the risk characterization, meaning health risks could not be fully
assessed. Little or no improvement is seen in public health risks because concern levels were
very low for all technologies, although formaldehyde cancer risks as high as from 1 x 10"7 to
3 x 10~7 were estimated for non-conveyorized and conveyorized electroless copper processes,
respectively.
In terms of worker health risks, conveyorized processes have the greatest benefits for
reduced worker inhalation exposure to bath chemicals; they are enclosed and vented to the
atmosphere. However, dermal contact from bath maintenance activities can be of concern
regardless of the equipment configuration for electroless copper, organic palladium, and tin-
palladium processes. No data were available for conveyorized non-formaldehyde electroless
copper processes (the same chemical formulations were assumed), but the non-conveyorized
version of this technology also has chemicals with dermal contact concerns.
The relative benefits and costs of technologies from changes in aquatic toxicity concerns
were more difficult to assess because only aquatic hazards were evaluated and not risk. Several
of the technologies contain copper sulfate, which has a very low aquatic toxicity concern
concentration (0.00002 mg/1). However, all of the technologies contain other chemicals with
high aquatic toxicity concern levels, although these chemicals are not as toxic as copper sulfate.
All of the alternatives provide significant social benefits in terms of energy and water
consumption, with the exception of energy consumption for the carbon technology. The drying
ovens used with this technology cause this technology to consume nearly as much energy per ssf
as the baseline.
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7.3 TECHNOLOGY SUMMARY PROFILES
7.3 TECHNOLOGY SUMMARY PROFILES
This section of the CTSA presents summary profiles of each of the MHC technologies.
The profiles summarize key information from various sections of the CTSA, including the
following:
• Generic process steps, typical bath sequences and equipment configurations evaluated in
the CTSA.
• Human health and environmental hazards data and risk concerns for non-proprietary
chemicals.
• Production costs and resource (water and energy) consumption data.
• Federal environmental regulations affecting chemicals in each of the technologies.
• The conclusions of the social benefits/costs assessment.
The first summary profile (Section 7.3.1) presents data for both the baseline process and
the conveyorized electroless copper process. Sections 7.3.2 through 7.3.7 present data for the
carbon, conductive polymer, graphite, non-formaldehyde electroless copper, organic-palladium,
and tin-palladium technologies, respectively.
As discussed in Section 7.2, each of the alternatives appear to provide private as well as
external benefits compared to the non-conveyorized electroless copper process (the baseline
process), though net benefits could not be assessed without a more thorough assessment of
effects on jobs and wages. However, the actual decision of whether or not to implement an
alternative occurs outside of the CTSA process. Individual decision-makers may consider a
number of additional factors, such as their individual business circumstances and community
characteristics, together with the information presented in this CTSA.
7.3.1 Electroless Copper Technology
Generic Process Steps and Typical Bath Sequence
>
Cleaner/ I ^
Conditioner I • ^
Catalyst 1 ^
'Water Rinse x2l ~
Water Ringe 1 21 — >•
Water Rinse x2|— >•
Microetch K >
Accelerator 1 — ^
b ^
yaterRinae s:2|— i"
Water Rinse 1 — ^
Predip 1 — i
1
kElectroless |
Copper f~\
\
1
Equipment Configurations Evaluated: Non-conveyorized (the baseline process) and
conveyorized.
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7.3 TECHNOLOGY SUMMARY PROFILES
Risk Characterization
Table 7.18 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the electroless copper technology. The risk characterization identified
occupational inhalation risk concerns for ten chemicals in non-conveyorized electroless copper
processes and dermal risk concerns for eight chemicals for either equipment configuration. No
public health risk concerns were identified for the pathways evaluated, although formaldehyde
cancer risks as high as 1 x 10'7 and 3 x 10"7 were estimated for non-conveyorized and
conveyorized electroless copper processes, respectively.
Table 7.18 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Electroless Copper Technology
Chemical*
Alkene Diol
Alkyl Oxide
Ammonium Chloride
Benzotriazole
Boric Acid
Copper (I) Chloride1
Copper Sulfate1
Cyclic Ether
Dimethylaminoborane
Dimethylformamide
Ethanolamine
2-Ethoxyethanol
Ethylenediaminetetraacetic
Acid (EDTA)
Ethylene Glycol
Fluoroboric Acid
Formaldehyde
Formic Acid
Hydrochloric Acid1
Hydrogen Peroxide
Sydroxyacetic Acid
Human Health Hazard and Occupational
l&fcsh
Inhalation.4
Toxicity"
(mg/m3)
NRf
NRf
ND
ND
ND
0.6
(LOAEL)
ND
ND
ND
0.03 (RfC)
12.7
(LOAEL)
0.2 (RfC)
ND
31
ND
0. 1 ppm
(LOAEL)
59.2
(NOAEL)
0.007 (RfC)
79
ND
Risk
Concerns
no
no
NA
NE
NE
yes
NE
NA
NE
no
yes
yes
NA
yes
NE
yes
yes
no
no
NE
Derittald
Toxieity*
-------
7.3 TECHNOLOGY SUMMARY PROFILES
Chemical3
Isopropyl Alcohol;
or 2-Propanol
m-Nitrobenzene Sulfonic
Acid
Magnesium Carbonate
Methanol
Nitrogen Heterocycle
Palladium
Peroxymonosulfuric Acid
Potassium Bisulfate
Potassium Cyanide
Potassium Hydroxide
Potassium Persulfate
Potassium Sodium Tartrate
Potassium Sulfate
Sodium Bisulfate
Sodium Carbonate
Sodium Carboxylate
Sodium Chlorite
Sodium Cyanide
Sodium Hydroxide
Sodium Hypophosphite
Sodium Sulfate
Stannous Chloride
Sulfuric Acid
Tartaric Acid
Tin Salt
p-Toluene Sulfonic Acid
Triethanolamine
Human Health Hazard and Occupational
Bisfcsh
Inhalation*
Toxicityc
(mg/m3)
980
(NOAEL)
ND
Bisk
Concerns
no
NE
Dermal'1
Toxieity*
(mg/kg-d)
100 (NOAEL)
ND
Risk
Concerns
no
NE
Generally regarded as safe
(U.S. FDA as cited in HSDB, 1995)
1,596 -
10,640
ND
ND
ND
ND
ND
7.1
ND
yes
NA
NA
NA
NE
NE
no
NE
0.5 (RfD)
NR
0.95 (LOAEL)
ND
ND
0.05 (RfD)
ND
ND
no
yes
yes
NE
NE
no
NE
NE
Generally regarded as safe
(U.S. FDA as cited in HSDB, 1996)
15 1.0>
0.79
0.08
0.92
ND
0.11
0.058
2.4
NR
0.00016
0.79
2.5
O.OQ&
0.81
0.0009
2.0
1.0
NR
l.O1
0.18
b Risk concerns are for MHC line operators (the most exposed individual).
0 Inhalation risk concerns for non-conveyorized process only. Inhalation risk from fully enclosed, conveyorized
process is assumed to be negligible,
d Dermal risk concerns apply to both conveyorized and non-conveyorized equipment
7-41
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7.3 TECHNOLOGY SUMMARY PROFILES
' Toxioity measure is RfC, RfD, NOAEL, or LOAEL as indicated. If not indicated, the type of toxicity measure
was not specified in the available information, but assumed to be LOAEL in risk calculations.
f Toxicity data are available but not reported in order to protect proprietary chemical identities.
* Specific EPA and/or IARC groups not reported in order to protect proprietary chemical identities.
h Estimated using ECOSAR computer software, based on structure-activity relationship.
1 Either copper (I) chloride or copper sulfate was in all electroless copper lines evaluated.
j Estimated by EPA's Structure-Activity Team.
k Cancer risk was not evaluated because no slope (unit risk) factor is available.
1 Hydrochloric acid was listed on the MSDSs for five of six electroless copper lines.
ra Chronic dermal toxicity data are not typically developed for strong acids.
ND: No Data. No toxicity measure available for this pathway.
NE: Not Evaluated; due to lack of toxicity measure.
NA: Not Applicable. Inhalation exposure level was not calculated bepause the chemical is not volatile (vapor
pressure below 1 x Id'3 torr) and is not used in any air-sparged bath.
MR: Not Reported.
Performance
The performance of the electroless copper technology was demonstrated at seven test
facilities, including six sites using non-conveyorized equipment and one site using conveyorized
equipment. Performance test results were not differentiated by the type of equipment
configuration used. The Performance Demonstration determined that each of the alternative
technologies has the capability of achieving comparable levels of performance to electroless
copper.
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and
energy) consumed. This information was used with a hybrid cost model of traditional cost (i.e.,
capital costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and
water and energy consumption per ssf. Average manufacturing costs for the baseline process
(the non-conveyorized electroless copper process) were $0.51/ssf, while water and energy
consumption were 11.7 gal/ssf and 573 Btu/ssf, respectively. However, the conveyorized
electroless copper process consumed less water and energy and was more cost-effective than the
baseline process (non-conveyorized electroless copper). Figure 7.1 lists the results of the
production costs and resource consumption analyses for the conveyorized electroless copper
process and illustrates the percent changes in costs and resource consumption from the baseline.
Manufacturing costs, water consumption, and energy consumption are less than the baseline by
71 percent, 90 percent, and 76 percent, respectively.
Regulatory Concerns
Chemicals contained in the electroless copper technology are regulated by the Clean
Water Act, the Safe Drinking Water Act, the Clean Air Act, the Superfund Amendments and
Reauthorization Act, the Emergency Planning and Community Right-to-Know Act, and the
Toxic Substances Control Act. In addition, the technology generates wastes listed as hazardous
(P or U wastes) under RCRA.
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7.3 TECHNOLOGY SUMMARY PROFILES
Figure 7.1 Production Costs and Resource Consumption of Conveyorized Electroless
Copper Technology
(Percent Change from Baseline with Actual Values in Parentheses)
o
-100
Production Costs
Energy Consumption
Con-veyorized
Boa Water Consumption
Social Benefits and Costs
A qualitative assessment of the private and external (e.g., social) benefits and costs of the
baseline and alternative technologies was performed to determine if there would be net benefits
to society if PWB manufacturers switched to alternative technologies from the baseline. It was
concluded that all of the alternatives, including the conveyorized electroless copper process,
appear to have net societal benefits, though net benefits could not be completely assessed without
a more thorough assessment of effects on jobs and wages. For the conveyorized electroless
copper process this is due to reduced occupational inhalation risk as well as to lower production
costs and to reduced consumption of limited resources (water and energy).
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7.3 TECHNOLOGY SUMMARY PROFILES
7.3.2 Carbon Technology
I
L
Clewier 1 >- Water Riase I ^ Carbon Blj
ict • ;jp* Air iLaixc/jJxy • — jp*- Wntei Riusc I -
Coadltioner 1 — >* Water Rinse 1 >. Carbon Ble
. Water Rinse 1
CrV I W. A ir ITflifr/nrv 1 ^- MirrAftfrlh 1
Equipment Configurations Evaluated: Conveyorized.
Risk Characterization
Table 7.19 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the carbon technology. The risk characterization identified no human
health risk concerns for the pathways evaluated. However, proprietary chemicals are not
included in this assessment and toxicity data were not available for some chemicals in carbon
technology baths.
Performance
The performance of the carbon technology was demonstrated at two test facilities. The
Performance Demonstration determined that this technology has the capability of achieving
comparable levels of performance to electroless copper.
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resource (water and energy)
consumed. This information was used with a hybrid cost model of traditional costs (i.e., capital
costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and water
and energy consumption per ssf. The conveyorized carbon technology consumed less water and
energy and was more cost-effective than the baseline process (non-conveyorized electroless
copper). Figure 7.2 lists the results of these analyses and illustrates the percent changes in costs
and resources consumption from the baseline. Manufacturing costs, water consumption, and
energy consumption are less than the baseline by 65 percent, 89 percent, and 9.6 percent,
respectively.
7-44
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7.3 TECHNOLOGY SUMMARY PROFILES
Table 7.19 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Carbon Technology
Chemical*
Carbon Black
Copper Sulfate
Ethanolamine
Ethylene Glycol
Potassium Carbonate
Potassium Hydroxide
Sodium Persulfate
Sulfuric Acid
Human Health Hazard aad Occupational
RIsksb
Inhalation"
Toxic%d
(mg/m3)
7.2 (LOAEL)
ND
12.7 (LOAEL)
31
ND
7.1
ND
0.066 (NOAEL)
Dermal
Toxicity"
(mg/kg-d)
ND
ND
320 (NOAEL)
2(RfD)
ND
ND
ND
ND
Risk
Concerns
NE
NE
no
no
NEe
NE '
NE
NEf
Carcinogetticlty
Weight-of-
Evidence
Clarification
IARC2B
none
none
none
none
none
none
none
Aquatic
ToxMty
CC
(mgfl)
ND
0.00002
0.075
3.3
>3.0
0.08
0.065
2.0
a Only one carbon technology was evaluated. All chemicals listed were present in that product line.
b Risk evaluated for conveyorized process only. Risk concerns are for line operator (the most exposed individual).
0 Exposure and risk not calculated. Inhalation exposure and risk from fully enclosed, conveyorized process is
assumed to be negligible.
d Toxiciry measure is RfC, RfD, NOAEL, or LOAEL, as indicated. If not indicated, the type of toxicity measure
was not specified in the available information, but assumed to be a LOAEL in risk calculations.
e Chemical has very low skin absorption (based on EPA's Structure-Activity Team evaluation); risk from dermal ,
exposure not expected to be of concern.
f Chronic dermal toxicity data are not typically developed for strong acids.
ND: No Data. No toxiciry measure available for this pathway.
NE: Not Evaluated; due to lack of toxiciry measure.
Regulatory Concerns
Chemicals contained in the carbon technology are regulated by the Clean Water Act, the
Safe Drinking Water Act, the Clean Air Act, the Superfund Amendments and Reauthorization
Act, and the Emergency Planning and Community Right-to-Know Act. The technology does not
generate wastes listed as hazardous (P or U waste) under RCRA, but some wastes may have
RCRA hazardous characteristics.
Social Benefits and Costs
A qualitative assessment of the private and external benefits and costs of this technology
suggests there would be net benefits to society if PWB manufacturers switched to the carbon
technology from the baseline. Among other factors, this is due to lower occupational risks to
workers and to reduced consumption of limited resources (water and, to a lesser degree, energy).
T45"
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7.3 TECHNOLOGY SUMMARY PROFILES
Figure 7.2 Production Costs and Resource Consumption of Carbon Technology
(Percent Change from Baseline with Actual Values in Parentheses)
-100
Conveyorizcd
Production Costs
Energy Consumption
Water Consumption
7.3.3 Conductive Polymer Technology
Generic Process^Steps and Typical Bath Sequence
Mioroetch
I—>• Water Rinse r »—>•
H
Catalyst
Water Rinse i 21 — >»
Conductive
Polymer
K
Water Rinse x 2 1 ^
Microeteh 1 — j^»
Copper Flash 1
Equipment Configurations Evaluated: Conveyorized.
Risk Characterization
Table 7.20 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the conductive polymer technology. The risk characterization identified
no human health risk concerns for the pathways evaluated. However, proprietary chemicals are
not included in this assessment and no toxicity data are available for some chemicals in
conductive polymer technology baths.
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7.3 TECHNOLOGY SUMMARY PROFILES
Table 7.20 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Conductive Polymer Technology
Chemical*
IH-Pyrrole
Peroxymonosulfuric Acid
Phosphoric Acid ;
Sodium Carbonate
Sodium Hydroxide
Sulfuric Acid
Human Health Hazard and Occupational
Risks"
Inhalation"
Toxocity*
(mg/m3)
ND
ND
ND
10 (NOAEL)
2 (LOAEL)
0.066 (NOAEL)
Dermal
Toxicity"
(mg/kg-d)
ND
NDe
ND
ND
ND
ND
Risk
Concerns
NE
ND
NEf
NE
NE
NEf
Carcinogenicity
Weight-of-
Evidence
Classification
none
none
none
none
none
none
Aquatic
Toxiclty
CC
(mg/t)
0.21
0.030
0.138
2.4
2.5
2.0
•*• »-"' J. J. •
b Risk evaluated for conveyorized process only. Risk concerns are for line operator (the most exposed individual).
c Exposure and risk not calculated. Inhalation exposure and risk from fully enclosed, conveyorized process is
assumed to be negligible.
d Toxicity measure is RfC, RfD, NOAEL, or LOAEL, as indicated. If not indicated, the type of toxicily measure
was not specified in the available information, but assumed to be a LOAEL in risk calculations.
e Chemical has very low skin absorption (based on EPA's Structure-Activity Team evaluation); risk from dermal
exposure not expected to be of concern.
f Chronic dermal toxicity data are not typically developed for strong acids.
ND: No Data. No toxicity measure available for this pathway.
NE: Not Evaluated; due to lack of toxicity measure.
Performance
The performance of the conductive polymer technology was demonstrated at one test
facility. The Performance Demonstration determined that this technology has the capability of
achieving comparable levels of performance to electroless copper.
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and
energy) consumed. This information was used with a hybrid cost model of traditional costs (i.e.,
capital costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and
water and energy consumption per ssf.
The conveyorized conductive polymer technology consumed less water and energy than
the baseline process (non-conveyorized electroless copper). Figure 7.3 lists the results of these
analyses and illustrates the percent changes in resources consumption from the baseline.
Manufacturing costs, water consumption, and energy consumption are less than the baseline by
82 percent, 94 percent, and 83 percent, respectively.
7-47
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7.3 TECHNOLOGY SUMMARY PROFILES
Figure 7.3 Production Costs and Resource Consumption of Conductive Polymer Technology
(Percent Change from Baseline with Actual Values in Parentheses)
-100
Production Costs
Enargy Conanmption
Conveyorized
8§j W»t»r Consumption
Regulatory Concerns
Chemicals contained in the conductive polymer technology are regulated by the Clean
Water Act, the Clean Air Act, and the Emergency Planning and Community Right-to-Know Act.
The technology does not generate wastes listed as hazardous (P or U waste) under RCRA, but
some wastes may have RCRA hazardous characteristics.
Social Benefits and Costs
A qualitative assessment of the private and external benefits and costs of this technology
suggests there would be net benefits to society if PWB manufacturers switched to the conductive
polymer technology from the baseline. Among other factors, this is due to lower occupational
risks to workers and to reduced consumption of limited resources (water and energy).
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7.3 TECHNOLOGY SUMMARY PROFILES
7.3.4 Graphite Technology
Cleaner/ Ij ^
Conditioner 1 ~
Water Rinse | — ^ Graphite | — ^ Fixer (optic
Microetth 1 — J^>
Water Rinse x 2 1
«tal)|->- AirKnife/Diy j^
1
Equipment Configurations Evaluated: Conveyorized.
Risk Characterization
Table 7.21 summarizes human and environmental hazards and risk concerns for chemicals
in the graphite technology. The risk characterization identified no human health risk concerns for
the pathways evaluated. However, the identification of proprietary chemicals was only provided
by one^of the two companies that submitted information concerning the graphite process. In
addition, toxicity data was not available from some chemicals in the graphite technology baths.
Performance
The performance of the graphite technology was demonstrated at three test facilities. The
Performance Demonstration determined that this technology has the capability of achieving
comparable levels of performance to electroless copper.
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and
energy) consumed., This information was used with a hybrid cost model of traditional costs (i.e.,
capital costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and
water and energy consumption per ssf. The conveyorized graphite technology consumed less
water and energy and was more cost-effective than the baseline process (non-conveyorized
electroless copper). Figure 7.4 lists the results of these analyses and illustrates the percent
changes in costs and resource consumption from the baseline. Manufacturing costs, water
consumption, and energy consumption are less than the baseline by 57 percent, 96 percent, and
63 percent, respectively.
Regulatory Concerns
Chemicals contained in the graphite technology are regulated by the Clean Water Act, the
Safe Drinking Water Act, the Clean Air Act, the Superfund Amendments and Reauthorization
Act, and the Emergency Planning and Community Right-to-Know Act. The technology does not
generate wastes listed as hazardous (P or U waste) under RCRA, but some wastes may have
RCRA hazardous characteristics.
7-49
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7.3 TECHNOLOGY SUMMARY PROFILES
Table 7.21 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Graphite Technology
Chemical8
Alkyl Oxide
Ammonia
Copper Sulfate; or
Cupric Sulfate
Cyclic Ether
Ethanolamine
Graphite
Peroxymonosulfuric Acid
Potassium Carbonate
Sodium Persulfate
Sulfuric Acid
Human Health Hazard and Occupational
Jtpfesb
Inhalation0
Toxicity*
(mg/m3)
ND
0.1 (RfC)
ND
ND
12.7 (LOAEL)
56 (LOAEL)
ND
ND
ND
0.066 (NOAEL)
Dermal
Toxicityd
(mg/kg-d)
NRe
ND
ND
NRS
320 (NOAEL)
ND
NDh
NDh
ND
ND
Risk
Concerns
no
NE
NE
no
no
NE
NE
NE
NE
NEJ
Carcinogenicfty
Weight-^
Evidence
Classification
Probable human
carcinogen*
none
none
Possible/
probable human
carcinogenf
none
none
none
none
none
none
Aquatic
Toxictty
CC
<*»g/l)
NR
0.0042
0.00002
NR
0.075
ND8
0.0301
>3.0
0.065
2.0
* Chemicals in bold were in both graphite technologies evaluated.
b Risk evaluated for conveyorized process only. Risk concerns are for line operator (the most exposed individual).
0 Exposure and risk not calculated. Inhalation exposure and risk from fully enclosed, conveyorized process is
assumed to be negligible.
d Toxicity measure is RfC, RfD, NOAEL, or LOAEL, as indicated.
* Toxicity data are available but not reported in order to protect proprietary chemical identities.
f Specific EPA and/or IARC groups not reported in order to protect proprietary chemical identities.
g Not expected to be toxic at saturation levels (based on EPA Structure-Activity Team evaluation).
K Chemical has very low skin absorption (based on EPA's Structure-Activity Team evaluation); risk from dermal
exposure not expected to be of concern.
1 Estimated by EPA's Structure-Activity Team.
j Chronic toxicity data are not typically developed for strong acids.
ND: No Data. No toxicity measure available for this pathway.
NE: Not Evaluated; due to lack of toxicity measure.
NR: Not Reported.
Social Benefits and Costs
A qualitative assessment of the private and external benefits and costs of this technology
suggests there would be net benefits to society if PWB manufacturers switched to the carbon
technology from the baseline. Among other factors, this is due to lower occupational risks to
workers and to reduced consumption of limited resources (water and energy).
7-50
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7.3 TECHNOLOGY SUMMARY PROFILES
Figure 7.4 Production Costs and Resource Consumption of Graphite Technology
(Percent Change from Baseline with Actual Values in Parentheses)
•100
Production Cent*
Energy Consumption
Ccmveyorized
^ W»Ur Consumption
7.3.5 Non-Formaldehyde Electroless Copper Technology
Generic Process Steps and Typical Bath Sequence
u
L
Cleaner/
Conditioner
}^
Water Rinse x 2|— ?*•
Microetch 1 — ^*
Water Kind* x 2 1 >
Predip 1— i
Cataryet 1— >•
Postdip 1-5^
Water Rinse 1 ^
Accelerator 1 — ^>-
Water Rinie 1-
Electrolese Copper/I ^__
Copper Flash | ^"
Water Rinse jc2|— >«
Anti-Tarnish 1
Equipment Configurations Evaluated: Non-conveyorized.
7-51
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7.3 TECHNOLOGY SUMMARY PROFILES
Risk Characterization
Table 7.22 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the non-formaldehyde electroless copper technology. The risk
characterization identified occupational inhalation risk concerns for one chemical and dermal risk
concerns for two chemicals. No public health risk concerns were identified for the pathways
evaluated. However, proprietary chemicals are not included in this assessment and toxicity values
were not available for some chemicals.
Table 7.22 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Non-Formaldehyde Electroless Copper Technology
Chemical*
Copper Sulfate
Hydrochloric Acid
Hydrogen Peroxide
Isopropyl Alcohol; or
2-Propanol
Potassium Hydroxide
Potassium Persulfate
Sodium Chlorite
Sodium Hydroxide
Stannous Chloride
Sulfuric Acid
Human Health Hazard and Occupational
Risks1'
Inhalation
Toxicity6
(mg/m5)
ND
0.007 (RfC)
79
980
(NOAEL)
7.1
ND
ND
2 (LOAEL)
ND
0.066 (NOAEL)
Risk
Concerns
NE
NA
no
no
no
NE
NA
no
NA
yes
Dermal
Toxicity'
(mg/kg-d)
ND
NDd
630 (NOAEL)
100
(NOAEL)
ND
ND
10 (NOAEL)
ND
0.62 (RID)
NDd
Risk
Concerns
NE
NE
no
no
NE
NE
yes
ND
yes
NE
Carcinogenicity
Weight-of-
Evidence
Classification
none
IARC Group 3
IARC Group 3
none
none
none
none
none
none
none
Aquatic
Toxicity
CC
(«ttg/l>
0.00002
0.1
1.2
9.0
0.08
0.92
0.00016
2.5
0.0009
2.0
* Only one non-formaldehyde electroless copper technology was evaluated. All chemicals listed were present in that
product line.
b Risk evaluated for non-conveyorized process only. Inhalation risk from fully enclosed, conveyorized process is
assumed to be low. Risk concerns are for line operator (the most exposed individual).
0 Toxicity measure is RfC, RfD, NOAEL, or LOAEL, as indicated. If not indicated, the type of toxicity measure
was not specified in the available information, but assumed to be a LOAEL in risk calculations.
d Chronic toxicity data are not typically available for strong acids.
ND: No Data. No toxicity measure developed for this pathway.
NE: Not Evaluated; due to lack of toxicity measure.
NA: Not Applicable. Inhalation exposure level was not calculated because the chemical is not volatile (vapor
pressure below 1 x 10"3 torr) and is not used in any air-sparged bath.
Performance
The performance of the non-formaldehyde electroless copper technology was
demonstrated at two test facilities. The Performance Demonstration determined that this
technology has the capability of achieving comparable levels of performance to electroless
copper.
TBT
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7.3 TECHNOLOGY SUMMARY PROFILES
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and
energy) consumed. This information was used with a hybrid cost model of traditional costs (i.e.,
capital costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and
water and energy consumption per ssf. The non-conveyorized non-formaldehyde electroless
copper process consumed less water and energy and was more cost-effective than the baseline
process (non-conveyorized electroless copper). Figure 7.5 lists the results of these analyses and
illustrates the percent changes in costs and resource consumption from the baseline.
Manufacturing costs, water consumption, and energy consumption are less than the baseline by
22 percent, 68 percent, and 53 percent, respectively.
Figure 7.5 Production Costs and Resource Consumption of Non-Formaldehyde
Electroless Copper Technology
(Percent Change from Baseline with Actual Values in Parentheses)
-100
Non-Coaveyorized
Production Costs
Energy CoiisDmption
Water Consumption
7-53
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7.3 TECHNOLOGY SUMMARY PROFILES
Regulatory Concerns
Chemicals contained in the non-formaldehyde electroless copper technology are regulated
by the Clean Water Act, the Safe Drinking Water Act, the Clean air Act, the Superfund
Amendments and Reauthorization Act, the Emergency Planning and Community Right-to-Know
Act, and the Toxic Substances Control Act. The technology does not generate wastes listed as
hazardous (P or U waste) under RCRA, but some wastes may have RCRA hazardous
characteristics.
Social Benefits and Costs
A qualitative assessment of the private and external benefits and costs of this technology
suggests there would be net benefits to society if PWB manufacturers switched to the non-
formaldehyde electroless copper technology from the baseline. Among other factors, this is due
to lower occupational risks to workers and to reduced consumption of limited resources (water
and energy).
7.3.6 Organic-Palladium Technology
>.
Cleaner j >•
Water Rinse I — ^ Microeteh 1 ^ Water Rin
Water Rinso 1 — >•
Pnsdip 1 >• Conductor 1 ^" Water Ria
Water Rinse |— >
Acid Dip 1
BS 1 — > Postdip |_
Equipment Configurations Evaluated: Non-conveyorized and conveyorized.
Risk Characterization
Table 7.23 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the organic-palladium technology. The risk characterization identified
occupational dermal risk concerns for one chemical, palladium salt. No occupational inhalation
risk concerns were identified. The risk characterization identified public health risk concerns for
the pathways evaluated. However, proprietary chemicals are not included in this table and
toxicity data were not available for some chemicals.
7-54
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7.3 TECHNOLOGY SUMMARY PROFILES
Table 7.23 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Organic-Palladium Technology
Chemical"
Hydrochloric Acid
Palladium Salt
Sodium Bisulfate
Sodium Carbonate
Sodium Bicarbonate
Sodium Hypophosphite
Sodium Persulfate
Trisodium Citrate 5,5-
Hydrate or Sodium Citrate
Human Health Hazard and Occupational
Risks"
Inhalation'
Toxicity*
(mg/m*>
0.007 (RfC)
ND
ND
10 (NOAEL)
10 (NOAEL)1
ND
ND
ND
Risk
Concerns
NA
NA
NA
NA
NA
NA
NA
NA
Dermal*
Toxiehy
(mg/kg-d)
NDf
NRg
NDh
ND
ND
ND
ND11
ND
Risk
Concerns
NE
yes
NE
NE
NE
NE
NE
NE
Carchtogenicity
Weight-ol-
Evidence
Classification
IARC Group 3
none
none
none
none
none
none
none
Aquatic
Toxicity
CC
-------
7.3 TECHNOLOGY SUMMARY PROFILES
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and
energy) consumed. This information was used with a hybrid cost model of traditional cost (i.e.,
capital costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and
water and energy consumption per ssf. With either equipment configuration, the organic-
palladium technology consumed less water and energy and was more cost-effective than the
baseline process (non-conveyorized electroless copper). In addition, the conveyorized organic-
palladium process consumed less water than the non-conveyorized process ($1.13 gal/ssf vs.
$1.35 gal/ssf, respectively), but'consumed more energy (148 Btu/ssf vs. 66.9 Btu/ssf). However,
the conveyorized organic-palladium is not as cost effective as the non-conveyorized process
($0.17/ssf vs. $0.15/ssf, respectively). Figure 7.6 lists the results of these analyses and illustrates
the percent changes in costs and resource consumption for either equipment configuration from
the baseline.
Figure 7.6 Production Costs and Resource Consumption of Organic-Palladium Technology
(Percent Change from Baseline with Actual Values in Parentheses)
(1.35 gal/ssfl (66.9 Btn/ssf)
-100
Conveyoiizsd
Production Costs
Energy Contumption
Non-Conveyorized
Water Consumption
7-56
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7.3 TECHNOLOGY SUMMARY PROFILES
Regulatory Concerns
Chemicals contained in the organic-palladium technology are regulated by the Clean
Water Act, the Clean Air Act, and the Emergency Planning and Community Right-to-Know Act.
The technology does not generate wastes listed as hazardous (P or U waste) under RCRA, but
some wastes may have RCRA hazardous characteristics.
Social Benefits and Costs
A qualitative assessment of the private and external (e.g., social) benefits and costs of this
technology suggests there would be net benefits to society if PWB manufacturers switched to the
organic-palladium technology from the baseline. Among other factors, this is due to lower
occupational risks to workers and to reduced consumption of limited resources (water and
energy).
7.3.7 Tin-Palladium Technology
Generic Process Steps and Typical Bath Sequence
Cleaner/
Conditioner
J^
Water Rinse x 2\ — }»
Mieroeteh. 1 — J^-
W Bter Rinse 1 2 1 >•
Predip ^
C»t«lyrt I >-
Water Rinse is. 2! — j»»
Accelerator 1 — J^>
Water Ria»e x 2 1 — }^-
Acid Dip
1
Equipment Configurations Evaluated: Non-conveyorized and conveyorized.
Risk Characterization
Table 7.24 summarizes human and environmental hazards and risk concerns for non-
proprietary chemicals in the tin-palladium technology. The risk characterization identified
occupational inhalation risk concerns for two chemicals and dermal risk concerns for five
chemicals. No public health risk concerns were identified for the pathways evaluated. However,
five proprietary chemicals are not included in this table and toxicity values were not available for
some chemicals. At least two of these chemicals (potassium carbonate and sodium bisulfate)
have very low skin absorption, indicating risk from dermal exposure is not expected to be of
concern.
Performance
For the purposes of the Performance Demonstration project, the organic-palladium and
tin-palladium technologies were grouped together into a single palladium technology category.
The performance of the palladium technology was demonstrated at ten test facilities. The
Performance Demonstration determined that this technology has the capability of achieving
comparable levels of performance to electroless copper.
7-57
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7.3 TECHNOLOGY SUMMARY PROFILES
Table 7.24 Summary of Human Health and Environmental Hazard Data and Risk
Concerns for the Tin-Palladium Technology
Chemical*
1,3-Benzenediol
Copper (I) Chloride'
Copper Sulfater
Dimethylaminoborane
Ethanolamine
Fluoroboric Acid
Hydrochloric Acid1*
Hydrogen Peroxide
Isopropyl Alcohol;
or 2-Propanol
Lithium Hydroxide
Palladiumj
Palladium Chloride1
Phosphoric Acid
Potassium Carbonate
Sodium Bisulfate
Sodium Chloride
Sodium Hydroxide
Sodium Persulfate
Stannous Chloride™
Sulfuric Acidh
Triethanolamine
Vanillin
Human Health Hazard and Occupational Risksb
Inhalation6
Toxicity"
(mg/m3)
ND
0.6 (LOAEL)
ND
ND
12.7 (LOAEL)
ND
0.007 (RfC)
79
980 (NOAEL)
ND
ND
ND
ND
ND
ND
ND
2 (LOAEL)
ND
ND
0.066 (NOAEL)
ND
ND
Risk
Concerns
NA
no
NE
NA
yes
NE
NA
no
no
NA
NA
NA
NE
NA
NA
NA
NA
NE
NA
yes
NA
NE
Dermal"
Toxkity*
(mg/kg-d)
100 (NOAEL)
0.07 (LOAEL)
ND
ND
320 (NOAEL)
0.77
ND
630 (NOAEL)
100 (NOAEL)
ND
0.95 (LOAEL)
0.95 (LOAEL)
ND
NDk
NDk
ND
ND
ND
0.62 (RfD)
ND
32 (LOAEL)
64 (LOAEL)
Risk
Concerns
no
yes
NE
NE
no
yes
NE1
no
no
NE
yes
yes
ND
NE1
NE
NE1
NE
NE1
yes
NE1
no
no
Carcinogenicity
Weighty*
Evidence
Classification
IARC Group 3
EPA Class D
none
none
none
none
IARC Group 3
IARC Group 3
none
none
none
none
none
none
none
none
none
none
none
none
none
none
Aquatic
Tcwdeity
CC
(mg/l)
0.0025
0.0004
0.00002
0.007s
0.075
0.125
0.1
1.2
9.0
ND
0.00014
0.00014
0.138
>3.0
0.058
2.8
2.5
0.065
0.0009
2.0
0.18
0.057
b Risk concerns are for MHC line operators (the most exposed individual).
0 Inhalation risk concerns for non-conveyorized process only. Inhalation risk from fully enclosed, conveyorized
process is assumed to be negligible.
d Dermal risk concerns apply to both conveyorized and non-conveyorized equipment.
* Toxicity measure is RfC, RfD, NOAEL, or LOAEL as indicated. If not indicated, the type of toxicity measure was
not specified in the available information, but assumed to be a LOAEL in risk calculations.
f Either copper (I) chloride or copper sulfate was listed on the MSDSs for four of five tin-palladium lines evaluated.
8 Estimated by EPA's Structure-Activity Team.
h Hydrochloric and sulfuric acid were listed on the MSDSs for four of five tin-palladium lines evaluated.
1 Chronic dermal toxicity data are not typically developed for strong acids.
S Palladium or palladium chloride was listed on the MSDSs for three of five tin-palladium lines evaluated. The MSDSs
for the two other lines did not list a source of palladium.
k Chemical has very low skin absorption (based on EPA's Structure-Activity Team evaluation); risk from dermal
exposure not expected to be of concern.
T5T
-------
7.3 TECHNOLOGY SUMMARY PROFILES
1 Dermal exposure level for line operator of conveyorized equipment was in top ten percent of dermal exposures for all
MHC chemicals.
m Stannous chloride was listed on the MSDSs for four of the five tin-palladium lines evaluated. The MSDSs for the
remaining tin-palladium product line did not list a source of tin.
ND: No Data. No toxicity measure available for this pathway.
NE: Not Evaluated; due to lack of toxicity measure.
NA: Not Applicable. Inhalation exposure level was not calculated because the chemical is not volatile (vapor pressure
below 1 x 10"3 torr) and is not used in any air-sparged bath.
Production Costs and Resource Consumption
Computer simulation was used to model key operating parameters, including the time
required to process a job consisting of 350,000 ssf and the amount of resources (water and energy)
consumed. This information was used with a hybrid cost model of traditional cost (i.e., capital
costs, etc.) and activity-based costs to determine average manufacturing costs per ssf and water and
energy consumption per ssf. With either equipment configuration, the tin-palladium technology
consumed less water and energy and was more cost-effective than the baseline process (non-
conveyorized electroless copper). In addition, the conveyorized tin-palladium process consumed
less water and energy and was more cost-effective than the non-conveyorized process ($0.12/ssf vs.
$0.14/ssf, respectively). Figure 7.7 lists the results of these analyses and illustrates the percent
changes in costs and resource consumption for either equipment configuration from the baseline.
Figure 7.7 Production Costs and Resource Consumption of Tin-Palladium Technology
(Percent Change from Baseline with Actual Values in Parentheses)
(131 Btu/ssf)
(1.80 gal/ssf)
-100
Conveyorized
Production Costa
Energy Consumption
Non-Conveyorized
Water Consumption
7-59
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7.3 TECHNOLOGY SUMMARY PROFILES
Regulatory Concerns
Chemicals contained in the tin-palladium technology are regulated by the Clean Water Act,
the Safe Drinking Water Act, the Clean Air Act, the Superfund Amendments and Reauthorization
Act, the Emergency Planning and Community Right-to-Know Act, and the Toxic Substances
Control Act. In addition, the technology generates a waste listed as hazardous (U waste) under
RCRA.
Social Benefits and Costs
A qualitative assessment of the private and external (e.g., social) benefits and costs of this
technology suggests there would be net benefits to society if PWB manufacturers switched to the
tin-palladium technology from the baseline. However, this alternative contains chemicals of
concern for occupational inhalation risk (for non-conveyorized equipment configurations) and
occupational dermal contact risks (for either equipment configuration). Among other factors, net
social benefits would be due primarily to lower production costs and to reduced consumption of
limited resources (water and energy).
7-60
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REFERENCES
REFERENCES
HSDB. 1996. Hazardous Substances Data Bank. MEDLARS Online Information Retrieval
System, National Library of Medicine.
Keenan, Cheryl. 1997. Abt Associates, Inc. Personal communication with Lori Kincaid, UT
Center for Clean Products and Clean Technologies. April?.
Mishan, E.J. 1976. Cost-Benefit Analysis. Praeger Publishers: New York.
Smith, Ted, Silicon Valley Toxics Coalition and Greg Karras, Communications for a Better
Environment. 1997. "Air Emissions of Dioxins in the Bay Area." March 27. As cited
in personal communication to Lori Kincaid, UT Center for Clean Products arid Clean
Technologies. March 3.
U.S. Environmental Protection Agency (EPA). 1995. Printed Wiring Board Industry and Use
Cluster Profile. Design for the Environment Program. EPA Office of Pollution
Prevention & Toxics. Washington, D.C. EPA744-R-95-005. September.
U.S. Environmental Protection Agency (EPA). 1996. The Medical Costs of Selected Illnesses
Related to Pollutant Exposure. Draft Report. Prepared for Nicolaas Bouwes, U. S.
EPA Regulatory Impacts Branch, Economics and Technology Division, Office of
Pollution Prevention and Toxics. Washington, D.C. July.
U.S. Environmental Protection Agency (EPA). 1997. Implementing Cleaner Technologies in
the Printed Wiring Board Industry: Making Holes Conductive. EPA Office of Pollution
Prevention & Toxics. Washington, D.C. EPA 744-R-97-001. February.
Unsworth, Robert E. and James E. Neumann, 1993. Industrial Economics, Inc. Memorandum
to Jim DeMocker, Office of Policy Analysis and Review. Review of Existing Value of
Morbidity Avoidance Estimates: Draft Valuation Document. September 30.
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REFERENCES
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