Office of Research and
Development
Washington, DC 20460
EPA/600/R-92/114
July 1992
&EPA
Modifications to Reduce
Drag Out at a Printed
Circuit Board
Manufacturer
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EPA/600/R-92/114
'July 1992
MODIFICATIONS TO REDUCE DRAG OUT
AT A PRINTED CIRCUIT BOARD MANUFACTURER
by
Paul Pagel
Minnesota Technical Assistance Program
Minneapolis, Minnesota 55455
and
Teresa Harten
Project Officer
Pollution Prevention Research Branch
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
CR-815821-01-0
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
Printed on Recycled Paper
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DISCLAIMER
The information in this document has been funded wholly or in part by
the United States Environmental Protection Agency under Contract No. CR-
815821-01-0 to the University of Minnesota, Minnesota Technical Assistance
Program. It has been subjected to the Agency's peer and administrative
review, and it has been approved for publication as an EPA document. Mention
of trade names or commercial products does not constitute endorsement or
recommendation for use.
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FOREWORD
Today's rapidly developing technologies and industrial products and
practices frequently carry with them the increased generation of materials
that, if improperly dealt with, can threaten both public health and the
environment. The U.S. Environmental Protection Agency is charged by Congress
with protecting the Nation's land, air, and water resources. Under a mandate
of national environmental laws, the Agency strives to formulate and implement
actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. These laws direct the
EPA to perform research to define our environmental problems, measure the
impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for
planning, implementing, and managing research, development, and demonstration
programs to provide an authoritative, defensible engineering basis in support
of the policies, programs, and regulations of the EPA with respect to drinking
water, wastewater, pesticides, toxic substances, solid and hazardous wastes,
and Superfund-related activities. This publication is one of the products of
that research and provides a vital communication link between the researcher
and the user community.
This report, "Modifications to Reduce Drag Out at a Printed Circuit
Board Manufacturer," discusses evaluation of two low cost, low technology
modifications to rinsing operations at a printed circuit board manufacturer.
Both modifications reduce waste by reducing drag out of process chemicals from
the line. The information contained in this report should be helpful to
operators and designers of circuit board lines, and other closely related
metal finishing processes, in identifying and implementing waste reduction
technologies within their operations.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
iii
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ABSTRACT
The MnTAP/EPA WRITE project at Mi com, Inc. demonstrated the waste
reducing capability of two simple rinsing modifications on two processes that
are typically found within electronic circuit board manufacturing operations.
The simple, low (or no) cost, low technology changes that were made were
1) slowing the withdrawal rate of the racks containing the printed circuit
boards as they are pulled from concentrated process tanks and 2) combining an
intermediate withdrawal rate with a longer drain time over the process tanks
before transfer to the rinse tanks. As compared to baseline sampling, both
modifications significantly reduced drag out of concentrated copper containing
bath solutions into the rinse water systems that followed the bath tanks.
The two processes tested were: an etchant bath and the countercurrent
rinsing system following it and an electroless copper plating bath and the
countercurrent rinsing system following it. The reduction in drag out for the
micro-etch bath was 45% as a result of the first modification and 41% as a
result of the second modification. For the electroless bath, drag out was
reduced by 50% after the first modification and 52% after the second
modification.
By reducing drag out in these amounts, 203 and 189 grams of copper
per day were prevented from being discharged as waste in the rinse water waste
stream, for modifications 1 and 2 respectively. Because copper concentration
in rinse water was reduced, the potential for conserving rinse water flows was
also shown, although this was not directly tested. Rinse water flows could be
turned down proportionate to the reduction in drag out and still maintain the
same rinsing efficiencies.
The economic savings due to these reductions were calculated by
considering avoided cost of treatment of the rinse water and avoided charges
for water and sewer service. If implemented, the first modification would
save the company $3350 $2640 savings in treatment costs and $710 in avoided
water and sewer costs. The same figures for implementing the second
modification would be $3120 - $2460 in treatment costs and $660 in avoided
water and sewer charges. Since no capital costs were incurred in making the
changes, payback would be immediate.
This report is submitted in fulfillment of EPA Cooperative Agreement
No. CR-815821-01-0 by Minnesota Technical Assistance Program, University of
Minnesota, under the sponsorship of the U. S. Environmental Protection Agency.
The report covers a period from June 26, 1989 to December 30, 1990 and work
was completed as of December 30, 1990.
IV
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CONTENTS
DISCLAIMER ii
FOREWORD iii
ABSTRACT iv
CONTENTS v
INTRODUCTION 1
Program Objectives 1
Rinsing Operations at Plating Facilities 1
WRITE Company Selection '. . 2
WRITE Company Description 2
TECHNOLOGY DESCRIPTION: DRAG OUT REDUCTION 5
Benefits of Reducing Drag Out 5
Modifications for Micom 5
SAMPLING AND ANALYSIS 8
Baseline Sampling 9
First Modification Sampling 9
Second Modification Sampling 9
RESULTS 11
Differences in Drag Out Due to Rinsing Modifications 14
Quality Assurance Project Plan Results 15
DISCUSSION 18
Technical Evaluation 18
Economic Analysis 18
Implementation 19
Future Modifications 19
Transferring Project Results 20
RECOMMENDATIONS 21
BIBLIOGRAPHY 22
APPENDIX - Raw Data and Calculated Drag Out Values 23
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INTRODUCTION
The Waste Reduction Innovative Technology Evaluation (WRITE) Program
is a national research demonstration program designed to evaluate the use of
innovative engineering and scientific technologies to reduce the volume and/or
toxicity of wastes produced from the manufacture, processing, and use of toxic
materials. The U.S. EPA Office of Research and Development, Risk Reduction
Engineering Laboratory, and the Minnesota Technical Assistance Program (MnTAP)
entered into a cooperative agreement as part of the "WRITE Pilot Program with
State and Local Governments" in July, 1989. Funding of the WRITE program is
provided jointly by the EPA and the state and local governments. The joint
approach was chosen because state and local government officials are familiar
with local industry practices and regional manufacturing interests, and these
factors can affect the potential success and widespread applicability of
proposed pollution prevention technologies.
PROGRAM OBJECTIVES
The Minnesota/EPA WRITE program is one of seven such programs
nationwide. The program in Minnesota targets the metal finishing industry,
specifically rinsing processes within metal finishing operations, as the focus
of waste reduction evaluations. The two most effective methods for reducing
wastes from these rinsing processes are 1) reducing drag out, the carryover of
concentrated solutions from plating baths, and 2) practicing water
conservation.
The present report discusses the results of the first project
performed under the Minnesota/EPA WRITE program. The project evaluated
modifications which reduce drag out at a single plating line within a printed
circuit board manufacturing facility. It is hoped that by demonstrating the
success of the modification in a fully operational setting, the technology
will be transferred to other plating/rinsing systems within the company as
well as to other facilities within the metal finishing industry.
RINSING OPERATIONS AT PLATING FACILITIES
The basic plating operation involves submerging parts in a process
solution, then rinsing off the excess film of plating chemicals known as drag
out. This rinsing process can waste several pounds per day of expensive
plating chemicals which must be removed from the rinse water before rinse
waters can be discharged to the sewer to comply with effluent limit
requirements. More efficient rinsing operations could reduce the loss of
plating chemicals, saving on the material cost and reducing the amount of
waste to be managed (Cushnie, 1985).
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Rinsing is essentially an operation of dilution; its objective is to
dilute the dissolved chemicals on the surface of the work to the point where
they are insignificant, not only in their effect on the quality of the work
being processed, but also with respect to plating solution contamination in
the operation of a plating line over a long period of time. Efficient rinsing
is obtained when this objective is accomplished with the minimum use of water
(Durney, 1984). Reducing drag out should reduce treatment needs and allow for
reductions in the flow of water required for rinsing.
WRITE COMPANY SELECTION
Solicitation of metal plating companies for participation in the
WRITE Program began in early 1989 through newsletter articles, metal finishing
association presentations, and direct mailings. Twenty-five companies
responded with interest in evaluating source reduction opportunities via
rinsing modifications. Work began in mid-August 1989 when site visits were
conducted to assess each company's interest and applicability to the project.
Companies were evaluated for inclusion in the WRITE Program on the basis of a
number of criteria which included potential for pollution prevention,
willingness to make modifications, willingness to share information,
production variability, and measurable quantity and concentration of
contaminant to be reduced.
WRITE COMPANY DESCRIPTION
Micom Inc. was selected largely because of its willingness to make
changes and because of its relatively stable production. Micom is a medium-
sized job shop in New Brighton, Minnesota, employing approximately 240 people.
The company manufactures printed circuit boards under a number of military and
commercial contracts. Annual revenues for 1989 were $17 million. An average
production day consists of two eight-hour shifts with a work load of 1,000-
1,200 square feet (ft ) of panels.
Micom manufactures double-sided and multilayered printed circuit
boards. The average circuit board size is 18 inches by 21 inches with 8000
holes per panel. Printed circuit boards are produced by depositing and
etching metal from a fiberglass sheet (board). The steps in this process
include: cutting the boards to size, coating the boards with a photosensitive
material (resist), developing the resist, drilling holes, deburring, cleaning,
etching, plating the inside of the holes (using an electroless plating
process), and plating the boards; inspections are performed at many points
along the way. Water rinses follow many of these steps. All printed circuit
boards at Micom pass through the sensitize line (Figure 1). This line is used
to deposit copper onto the inside of the circuit board holes and consists of
micro-etch, activator, accelerator, electroless copper and rinse tanks.
The WRITE project tested changes to the operation of the micro-etch
bath and the two countercurrent rinses which follow it, and the electroless
copper bath and the two countercurrent rinses which follow it. Micom was
interested in evaluating modifications to the micro-etch and electroless
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^^^ Represents primary valve on each water line.
A Represents a sampling point.
Figure 1. Micom Sensitize Line
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copper plating and rinsing processes because these processes are significant
contributors of copper to the ion exchange system used to treat metal bearing
wastewaters. Softened water at a restricted flow of about 3 gallons per
minute makes up the influent to the countercurrent rinses following the micro-
etch bath and the electroless copper bath. The copper bearing waste stream
from the rinse tanks is piped to an ion exchange system for copper removal and
then sewered. The ion exchange canisters are regenerated off site.
The printed circuit boards enter the sensitive line in racks which
hold 24 boards each. The boards vary in size with the largest being 18 inches
by 24 inches. The racks are 34 inches by 19.5 inches wide by 13 inches deep
and are transported by a hoist from tank to tank. The operator controls the
hoist and allows the rack to drain 3-5 seconds before proceeding to the next
tank. The approximate residence time is 75 seconds in the micro-etch bath, 30
minutes in the electroless copper bath, and 2 to 3 minutes in each rinse bath.
The electroless copper plating process is the rate determining step
for production throughput. The plating tank holds two racks of printed
circuit boards which remain in the bath for 30 minutes each. In order to
maximize production, each pair of racks are started in the line at
approximately 30 minute intervals. This allows the electroless copper bath to
remain in use and minimizes the delay between plating each rack.
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TECHNOLOGY DESCRIPTION: DRAG OUT REDUCTION
BENEFITS OF REDUCING DRAG OUT
The micro-etch process prepares the printed circuit board for plating
by removing oxidized copper from its surface. Reducing the drag out from the
micro-etch process solution will also reduce the amount of water required for
rinsing and reduce the operating costs of the ion exchange wastewater
treatment system. However, the micro-etch process solution may require more
frequent replacement due to the additional buildup of copper which was
previously removed by drag out.
Reducing the copper drag out from the electroless copper plating
solution results in three possible benefits. If copper in the rinse water is
reduced by capturing the process solution before rinsing, raw material costs
may be reduced, since the need for chemical additions could be reduced by
returning process solution to the bath. Treatment costs may also be reduced,
especially where relatively expensive treatment is used to remove copper from
the rinse waters. In addition, reducing copper discharge by capturing process
solution can reduce the amount of water needed for rinsing, since less process
solution requiring dilution (rinsing) will be present.
Disposal of spent micro-etch and electroless baths included copper
recovery in both cases and regeneration of etchant in the case of the micro-
etch solution. When the micro-etch bath had to be removed from the line and
replaced with fresh bath it was company practice to reclaim copper from the
bath as copper sulfate and reuse it in another copper plating solution on
site. The etchant was regenerated and also used on site for less critical
operations such as stripping copper from carrier racks. The company also
recovered copper from the spent electroless copper bath, although the copper
was sent off site for reuse. Thus, copper-containing bath solution retained
in the process baths due to implementing drag out reduction changes would
ultimately be subjected to the company's recovery operations.
MODIFICATIONS FOR MICOM
At Micom, the criteria for selecting implementable rinsing process
modifications included: availability of equipment, impact of a modification
on process solutions, maintaining product quality, and effect on production
throughput. Production objectives (quality and throughput) were paramount, as
might be expected.
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Before the WRITE Program's involvement with Micom, the company had
already made modifications which reduced rinse water requirements including
the installation of countercurrent rinses, water flow restrictors, softened
water, air agitation and mechanical agitation. Countercurrent rinses had been
installed following the micro-etch and electroless copper process baths, and
water flow restrictors on rinse tank inlets maintained an approximate flow of
3 gallons per minute (gpm). Softened water was used in the copper bearing
rinses to improve rinsing and the efficiency of the ion exchange system. The
filled racks were mechanically agitated in each tank to force solution through
the circuit board holes, and some rinses were air agitated to increase the
dilution of the drag out by mixing the rinse.
The first modification that was evaluated at Micom was slowing the
rate of withdrawal of the racks from the process solution tanks. This was
accomplished by lowering the speed of the motor on the mechanical hoist used
for raising, lowering and transporting racks of circuit boards. The slower
rate of withdrawal allows the process solution viscosity to aid solution
removal by pulling the solution from boards like a squeegee. The total drain
time is also increased as the boards are being withdrawn more slowly, thereby
allowing the part to drain longer.
The effects of reducing the drag out on process solutions is an
important consideration. The micro-etch bath removes copper from the printed
circuit boards and continually builds up copper in the solution until it no
longer is able to remove copper. At this point, the bath is replaced with new
solution. For an etchant bath, retaining solution which was formerly lost to
drag out could mean the etchant bath must be replaced more often due to the
increased build-up of copper. However, managing the concentrated waste stream
which results from bath replacement is preferable to managing diluted rinse
waters because opportunities for metals recovery are improved if the
wastestream is concentrated. As previously discussed, at Micom, spent
concentrated micro-etch and electroless bath solutions were subjected to on-
site copper recovery processes, and for the micro-etch bath, an etchant
recovery process. Another advantage of reducing drag out to rinse water is
that rinse water can be reduced proportionate to drag out reduction, thereby
requiring less treatment chemicals and reducing sludge generation at on-site
wastewater treatment systems.
Retaining electroless plating solution which was formerly lost to
drag out could increase the life of the plating bath. Since fewer plating
chemicals are lost to drag out of solution, fewer chemical additions will be
required to maintain the chemical composition of the bath. However, a
filtration step may have to be added to remove impurities which were
previously removed by drag out. Drag out reduction from preceding tanks could
also lower the amount of impurities carried into the plating bath.
The second modification evaluated was increasing the drain time over
the process bath before transferring the racks into the rinse tanks. This was
accomplished by having the line operator wait longer (10 seconds for this
evaluation) before moving the draining rack to the rinse. The baseline
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withdrawal rate was not reproduced, for the second modification due to the
installation of a new air hoist, which could not be adjusted to exactly the
same withdrawal rate as the original hoist. This resulted in a withdrawal
rate that was slower than the baseline and faster than the first modification
This rate will be referred to as the "intermediate" withdrawal rate. The
combination of increased drain times and the intermediate withdrawal rate
allow solutions to drip back into the process tank, thus reducing the drag
out.
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SAMPLING AND ANALYSIS
To evaluate the modifications of the rinsing process, MnTAP
established a baseline for process solution drag out, rinse water use, rate of
rack withdrawal, and drain time for the Micom sensitize line. To measure the
drag out of solution from the process tank, the incoming softened water flow
to the rinse tanks was temporarily shut off. To account for copper already
present in the rinse tanks (Figure 1), samples were taken before and after a
known quantity of printed circuit boards were rinsed (one or two racks of 24
boards). The total copper concentration in the samples was analytically
determined by atomic absorption. The change in copper concentration was
calculated by subtracting the initial (before rinsing) concentration of copper
in each rinse from the final (after rinsing) concentration. The process tank
was sampled immediately after a rack of boards was removed. The surface area
of the printed circuit boards rinsed during the sample period was calculated
to enable a comparison based on square footage of production. The additional
mass of copper in the rinses is equal to the change in copper concentration in
the rinses multiplied by the volume of each rinse. The drag out was
calculated, as shown below, by dividing the total amount of copper in the
rinses by the concentration of the process solution and then normalizing the
result by dividing by the surface area of the boards processed. (Quality
Assurance Project Plan, Section III, page 7, 1990)
(change in copper
concentration in rinses) X (volume of rinses)
Drag out = mq/L ' m]
(ml/ftf)
(copper concentration (surface area
in process solution) X of boards)
mg/L ft2
The tank following the countercurrent rinses was sampled to check the amount
of copper build-up. This was monitored during the baseline period to indicate
the effectiveness of these rinses. This measurement provides a standard to
use while comparing rinse water reduction modifications.
The water flow rate was calculated by measuring the time it took to
fill a five gallon container from the rinse tank discharge. The rinse water
flow rate is expressed in gallons per minute. The withdrawal time was
determined by measuring the time it took to lift a rack of boards from the
process bath to the height needed to clear the wall of the tank (A to B in
Figure 2). The withdrawal height was 34 inches. The average withdrawal rate
was determined by dividing the height by the average withdrawal time.
8
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withdrawal height
Withdrawal Rate =
(ft/min)
average withdrawal time
The drain time was determined by measuring the time after the rack was
withdrawn until the rack was halfway over the next tank (B to C in Figure 3).
The total time is the sum of the withdrawal time and the drain time (A to C in
Figures 2 & 3).
BASELINE SAMPLING
The baseline samples were collected from March 12-23, 1990. The
micro-etch bath and rinses were sampled before and after a single rack of
printed circuit boards were rinsed. The electroless copper plating bath and
rinses were sampled before and after each pair of racks were rinsed. One
hundred thirty-six samples were analyzed to determine the volume of drag out
from the micro-etch and the electroless copper baths for twelve pairs of racks
over a two week period. The withdrawal time and total drain time were
measured for each rack transfer. The withdrawal rate was calculated from the
average withdrawal time. The flow rates of the rinses following the micro-
etch and electroless copper baths were monitored twelve times over two days.
The surface area of the boards in each rack was calculated from measurements
of the boards.
FIRST MODIFICATION SAMPLING
The first modification, slowing the rate of withdrawal, was tested on
November 15, 1990. One hundred thirty-six (136) samples were analyzed in
order to determine the volume of drag out from the micro-etch and the
electroless copper baths for twelve pairs of racks over a one day period. The
withdrawal time and total drain time were measured for each rack transfer.
The flow rates of the rinses were not sampled due to the water being turned
off to determine the drag out. The surface area of the boards in each rack
was calculated from measurements of the boards.
SECOND MODIFICATION SAMPLING
The second modification, increasing the drain time with an
intermediate withdrawal rate, was tested on December 10 and 11, 1990. One
hundred and nine samples (109) were analyzed in order to calculate the volume
of drag out from the micro-etch and the electroless copper baths for nine
pairs of racks over a two day period. The withdrawal time and total drain
time were measured for each rack transfer. During chemical sampling of the
rinse tanks, rinse water was turned off; flow rates were measured after the
rinse waters had been turned back on. The surface area of the boards in each
rack was calculated from measurements of the boards.
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Rinse
Tank
Process
Tank
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Figure 2. Rack Positions Used in Determining
Withdrawal Rate
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Figure 3. Rack Positions Used in Determining
Drain Time
10
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RESULTS
The calculated amount of drag out during the baseline evaluation was
12.1 ml/ft from the micro-etch bath and 6.0 ml/ft from the electroless
copper bath. Racks of printed circuit boards were withdrawn from the tanks
very quickly, usually taking less than two seconds. The average drain time
for racks being removed from the electroless copper bath was longer than those
removed from the micro-etch bath because of an additional distance some racks
travel while still draining over the wider electroless copper tank. The
results of the baseline evaluation are summarized in Tables 1 & 2.
TABLE 1. RESULTS OF BASELINE MICRO-ETCH EVALUATION
Average
Range
n Std.
Dev.
Low High
Drag out (ml/ft2) 12.1 9.3 14.5 12 1.5
Withdrawal Time (seconds) 1.7 1.0 3.2 12 0.8
Withdrawal Rate (ft/min) 100 - - -
Drain Time (seconds) 3.4 1.2 7.6 12 2.1
Total Time (seconds) 5.1 2.3 8.9 12 2.3
Surface Area/Rack (ft2) 88 48 126 12 24
Water Flow Rate (GPM) 2.6 2.5 2.7 6 0.04
11
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TABLE 2. RESULTS OF BASELINE ELECTROLESS COPPER EVALUATION
Average
Drag out (ml/ft2) 6.0
Withdrawal Time (seconds) 1.8
Range
Low
4.7
1.0
High
7.6
3.2
n
12
23
Std.
Dev.
1.1
1.6
Withdrawal Rate (ft/min) 94 - - '
Drain Time (seconds) 5.2 0.8 10.2 23 2.6
Total Time (seconds) 7.0 1.3 11.4 23 3.1
Surface Area/Rack (ft2) 169 124 234 12 33
Water Flow Rate (GPM) 3.3 3.2 3.3 6 0.05
The calculated amount of drag out during the evaluation of the first
modification was 6.7 ml/ft2 from the micro-etch bath and 3.0 ml/ft from the
electroless copper bath. Racks of printed circuit boards were withdrawn from
the tanks slowly, taking from thirteen to sixteen seconds. The results of the
first modification evaluation are summarized in Tables 3 & 4.
TABLE 3. RESULTS OF MODIFICATION 1 MICRO-ETCH EVALUATION -
SLOWED RATE OF WITHDRAWAL
Average Range
Drag out (ml/ft2)
Withdrawal Time (seconds)
Withdrawal Rate (ft/min)
Drain Time (seconds)
Total Time (seconds)
Surface Area/Rack (ft2)
6.7
14.9
11
2.5
17.4
83
Low
5.2
13.6
1.4
15.5
56
High
9.7
16.0
4.6
19.4
114
n
12
11
-
11
11
12
Std.
Dev.
1.3
0.7
-
0.9
1.1
14
12
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TABLE 4. RESULTS OF MODIFICATION 1 ELECTROLESS COPPER EVALUATION
SLOWED RATE OF WITHDRAWAL
Average Range n Std.
Dev.
Low High
Drag out (ml/ft2) 3.0 2.1 3.4 12 0.4
Withdrawal Time (seconds) 13.9 13.1 15.4 23 0.7
Withdrawal Rate (ft/min) 12 ...
Drain Time (seconds) 3.2 1.1 8.7 23 2.1
Total Time (seconds) 17.1 14.4 23.0 23 2.3
Surface Area/Rack (ft2) 162 104 220 12 32
The calculated amount of drag out during the evaluation of the second
modification was 7.1 ml/ft from the micro etch bath and 2.9 ml/ft from the
electroless copper bath. Racks of printed circuit boards were withdrawn from
the tanks slightly faster than the baseline but much slower than the first
modification, taking from two to five seconds. The results of the second
modification evaluation are summarized in Tables 5 & 6.
TABLE 5. RESULTS OF MODIFICATION 2 MICRO-ETCH EVALUATION
LONGER DRAIN TIME WITH INTERMEDIATE WITHDRAWAL RATE
Drag out (ml/ft2)
Withdrawal Time (seconds)
Withdrawal Rate (ft/min)
Drain Time (seconds)
Total Time (seconds)
Surface Area/Rack (ft2)
Average
7.1
4.3
40
12.1
16.4
92
Range
Low
5.5
2.1
-
11.2
13.7
60
High
8.2
5.6
-
13.7
18.0
119
n
12
10
-
10
10
10
Std.
Dev.
0.9
0.9
0.9
1.3
17
13
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TABLE 6 RESULTS OF MODIFICATION 2 ELECTROLESS COPPER EVALUATION
LONGER DRAIN TIME WITH INTERMEDIATE WITHDRAWAL RATE
Average Range n Std.
Dev.
Low High
Drag out (ml/ft2) 2.9 1.9 3.7 12 0.5
Withdrawal Time (seconds) 4.3 3.5 4.9 19 0.4
Withdrawal Rate (ft/min) 40 -
Drain Time (seconds) 11.9 11.1 16.4 19 1.2
Total Time (seconds) 16.3 15.0 20.5 19 1.2
Surface Area/Rack (ft2) 175 60 228 10 49
DIFFERENCES IN DRAG OUT DUE TO RINSING MODIFICATIONS
Slowing the rate of withdrawal (modification 1) lowered the drag out
from the micro-etch solution from the baseline drag out of 12.1 ml/ft to
6.7 ml/ft , while extending the drain time combined with an intermediate
withdrawal rate (modification 2) yielded a similar drag out of 7.1 ml/ft .
The drag out from the electro!ess copper plating bath was reduced from 6.0
ml/ft to 3.0 ml/ft2 when the withdrawal rate was slowed and reduced to 2.9
ml/ft2 after the drain time was lengthened using an intermediate withdrawal
rate.
These lower drag out volumes represent a 45 percent reduction for
modification 1 and 41 percent reduction for modification 2 from the micro-
etch; for the elecroless copper, modification 1 resulted in a 50 percent
reduction, while modification 2 resulted in a 52 percent reduction in drag
out. The differences in drag out are summarized in Table 7 and Table 8.
Comparisons of the baseline to each modification using statistical
analysis confirm significant reduction at an a error level less than 0.005.
This yields a confidence level greater than 99.5% when each modification is
compared to the baseline. The evaluation indicates a significant reduction in
drag out when the withdrawal rate is slowed or the drain time is increased
with an intermediate withdrawal rate. A statistical analysis to determine the
significance of the difference between modifications 1 and 2 was not
performed.
The reduction in drag out from the first modification was equivalent
to preventing 194 grams of copper from the micro-etch bath and 9 grams of
copper from the electroless bath per day from entering the rinse water waste
stream, for a total of 203 grams/day. The figures for the second modification
14
-------
TABLE 7. SUMMARY OF MICRO-ETCH RESULTS
BASELINE
MODIFICATION 1
slower rate of
withdrawal
MODIFICATION 2
longer drain time
with intermediate
withdrawal rate
Withdrawal
Rate
(ft/min)
100
11
40
TABLE 8. SUMMARY
BASELINE
MODIFICATION 1
Withdrawal
Rate
(ft/min)
94
12
Time
Withdrawal
(seconds)
1.7
14.9
4.3
Drain
Time
(seconds)
3.4
2.5
12.1
OF ELECTROLESS COPPER
Time
Withdrawal
(seconds)
1.8
13.9
Drain
Time
(seconds)
5.2
3.2
Total
Time
(seconds)
5.1
17.4
16.4
RESULTS
Total
Time
(seconds)
7.0
17.1
Dragout
(ml/ft2)
12.1
6.7
7.1
Dragout
(ml/ft2)
6.0
3.0
slower rate of
withdrawal
MODIFICATION 2
longer drain time
with intermediate
withdrawal rate
40
4.3
11.9
16.3
2.9
15
-------
are 180 grams prevented from leaving the micro-etch bath and 9 grams, for a
total of 189 grams/day, prevented from leaving the electroless bath. These
figures assumed a copper concentration of 30 grams/liter in the micro-etch
bath and 2.4 grams/liter in the electroless bath and a production level of
1200 ft of printed circuit board per day.
Because copper concentration in rinse water was reduced, the
potential for conserving rinse water flows was also shown, although this was
not directly tested. Rinse water flows could be turned down proportionate to
the reduction in drag out and still maintain the same rinsing efficiencies.
QUALITY ASSURANCE PROJECT PLAN RESULTS
Sampling procedures were followed according to the Quality Assurance
Project Plan (QAPjP). The baseline sampling was performed over a two week
period, the first modification was tested and sampled over a two shift period,
and the second modification was sampled over a two day period. A wide variety
of printed circuit boards were being manufactured during each of the sampling
periods. Although the boards were not identical in each case, they were
representative of the work at Micom.
To assure compliance with the QAPjP, field audits were conducted by
Barb Loida, MnTAP engineer. The auditor reviewed the field activities at
Micom such as sample collection, chain of custody, and sample information.
Analytical methods were followed according to the approved QAPjP by
PACE Laboratories, Inc., with the exception of the electroless copper plating
bath samples. These samples, when preserved with nitric acid according to
instructions from the laboratory, precipitated out the copper as the solution
cooled. The analytical procedure was modified to include preservation with a
hydrochloric/nitric acid mixture, digestion of the sample, and analysis for
total copper.
The analytical results for the electroless copper bath samples for
the baseline evaluation averaged 1600 mg/1 and one sample was lost due to a
laboratory accident during the digestion process. Despite additional
validation of the procedure, the results from the samples taken during the
first modification period averaged only 1800 mg/1 with one sample as low as
900 mg/1. The samples during the second modification averaged 2200 mg/1 after
the laboratory recalculated the results to account for the 30 ml of acid that
had been added to each sample per the modified analytical procedure.
These results do not compare well with the electroless copper bath
operating concentrations according to Micom's laboratory analysis and line
operating procedures. It should also be pointed out that an electroless
copper plating solution will not plate at such low copper concentrations.
This led to the decision to accept an average bath copper concentration of
2400 mg/L as determined by Micom process control charts and results from the
Micom laboratory. The control charts show an operating range of ± 100 mg/L of
copper; additions are automatically pumped into the plating bath as required.
16
-------
This average of 2400 mg/L was used in place of analytical results for the
electroless copper solution only, and was used for baseline, modification 1,
and modification 2 evaluation calculations.
Although the reason for the poor analytical results for the
electroless copper samples is not clear, several possibilities include:
improper acidification, plate out of sample on container walls, sample not
maintained at bath temperature of 103 F, or the results may not have been
adjusted to account for the addition of acid.
Quality control samples were analyzed for copper. Field blank,
precision - relative percent difference (RPD), and percent recovery - matrix
spike/matrix spike duplicates (MS/MSDs) were analyzed. Copper was not
detectable at the method detection limit in the field blanks. All of the RPDs
between duplicates were less than the 20 percent QC target range. All of the
percent recoveries were within the 75 to 125 percent recovery target range.
17
-------
DISCUSSION
TECHNICAL EVALUATION
Although possible, the ability to slow the mechanical hoist's rate of
withdrawal is complicated by a few items. The mechanical hoist at Mi com is
capable of a slower vertical rate, but this not only slows the rate of
withdrawal but also slows the rate of insertion. The slower overall rate
therefore demands more of the hoist's operating time, making it difficult to
move the hoist to the opposite end of the line in time to transfer another
rack, thus slowing production. The maximum horizontal speed of 40 feet per
minute is not fast enough to allow travel from one end to the other and still
maintain current production levels. The mechanical hoist was also prone to
breakdown, requiring repair.
The extended drain time was tested by manually signaling the rack
transfer after a ten second drain time over the copper bearing process
solutions. The line operator could implement this by counting to ten slowly
before transferring the rack.
ECONOMIC ANALYSIS
An economic evaluation showed that the company could save $2640 per
year in rinse water treatment and disposal costs by implementing modification
1 or $2460 per year by implementing modification 2. Rinse water was treated
using on-site ion exchange cannisters which had a capacity of 46 pounds of
copper before requiring off-site regeneration at a cost of $1096 per
cannister. Savings were calculated using the following formula:
(amount of copper prevented) (cost of canister)
Savings =
capacity of ion exchange canister
The savings do not take into account the time required to change the
peed of the hoist or train the operators to extend the drain time. The
additional time required to withdraw or drain the racks could be offset by
shortening some rinsing and/or holding times or by reducing the spacing
between production runs. One production run consists of a pair of racks which
enter the electroless copper bath at approximately the same time. Filled
racks are often held in rinse tanks or placed at the loading area before
entering the sensitize line. The electroless copper plating process is the
18
-------
rate determining step and a production run remains in this bath for 30 minutes
before being rinsed.
IMPLEMENTATION
For a number of site specific reasons the company decided to
implement a longer drain time to reduce drag out instead of altering the
withdrawal rate. As discussed above, the programmable mechanical hoist used
for modification 1 at Micom was unreliable and often broke down. Another
problem with the mechanical hoist at Micom was its inflexibility in
programming. To slow the withdrawal rate for modification 1 the vertical
speed had to be adjusted, thus slowing not only the withdrawal rates but also
the insertion rates; these rates were slowed for insertion and withdrawal into
all tanks on the sensitize line, not just the micro-etch and the electroless
tanks. In order to maintain production rates at previous levels, operators
supplemented the mechanical hoist with an air-assisted hoist.
As a result of recurrent break downs of the mechanical hoist and the
inability to specifically target and program slower withdrawal rates for the
two bath tanks, the company took the mechanical hoist out of service. Air-
assisted hoists were used as replacements. With this type operation it made
more sense for the company to implement a longer drain time to achieve drag
out reduction. The company believed that it would be easier to train
operators to increase the drain time over the two tanks rather than have them
slow withdrawal rates.
For modification 2 the additional time added to the sensitize line to
allow the intermediate withdrawal rate and longer drain time as compared to
baseline was 21 seconds. This amount was negligible when compared to the 60
minute total production time through the sensitize line. Minor modifications
to the operation of the line could offset the added time so that the baseline
production rate could be maintained. At Micom, filled racks were often held
beyond the necessary times in rinse tanks while processing in the sensitize
line or placed at the loading area before entering the line. Changes such as
shortening the timing between rack starts and/or reducing holding times in
rinse tanks that were known to be more than adequate could makeup for the
added 21 seconds.
FUTURE MODIFICATIONS
Once drag out reduction has been optimized, less water would be
required to maintain the cleanliness of the rinses. Using less water will
decrease water and sewer charges, which is especially important at Micom where
incoming water must be softened before use on the sensitize line. Decreased
rinse water volumes may reduce treatment costs by making the ion exchange
system at Micom more effective at removing copper from rinse water and by
reducing the amount of water which must pass through the resin beds.
19
-------
Water use can be reduced proportionately with contaminant reduction.
An additional savings of $710 per year for modification 1, or $660 for
modification 2, could be realized in avoided water and sewer charges if the
company reduced rinse water flow rates proportional to the reduced copper
contamination of the rinse water that would result from implementing the drag
out reducing modifications tested. Less water would also need to be softened,
but lower costs would not be evident as water softening is billed as a monthly
fee independent of water use. This fee may also be reduced through
negotiations with the water softening company.
MnTAP intended to maintain or improve the current rinsing
effectiveness. This was monitored during the baseline by checking the amount
of copper build-up in the non-flowing tank which follows the countercurrent
rinses. Copper buildup in tank 4, Figure 1, ranged between zero and 12 mg/1
over eight hours while copper buildup in tank 8 ranged between 0.01 and 0.08
mg/1. This monitoring was not continued during the modifications as the rinse
water was turned off for a considerable amount of time during the drag out
evaluations. These rinses should be monitored when the rinse water flow rates
are reduced. The buildup of copper in these tanks can be a good monitor of
the quality of the rinsing when it is compared to a baseline.
TRANSFERRING PROJECT RESULTS
For the Micom project, not only is the work centered on one process
line, but also further narrowed to concentrate on two process steps within
that line, the micro-etch and the electroless copper plating solution. The
reason for the narrow focus was first a matter of available budget for
performing the evaluation, since a limited amount of time and money is
available to perform the necessary sampling, analysis and data reduction for
such an evaluation. Another reason is that these two processes are the most
concentrated copper sources on the process line. The focus is also part of a
larger philosophy, one which MnTAP calls "planting seeds." The hope is that
if rinsing process modifications are demonstrated to be successful in one
location in a plating operation, plant management will be more likely to
attempt similar modifications on other process lines. Rather than attempting
plant-wide modifications, or changes applied to large, aggregated waste
streams, a staged approach is not only more manageable, but may improve
accuracy of cost and product quality assessments.
20
-------
RECOMMENDATIONS
Besides the two objectives of reducing copper discharge and water
use, in the future MnTAP plans to develop and test a procedure for evaluating
and modifying rinsing processes which will be transferable to and useful to
other operations. This procedure would address such imperatives as protecting
product quality while modifying the production process, evaluating the impact
of modifications on production throughput, and providing a "rule-of-thumb" for
such decisions as number of samples required for evaluation. This procedure
will be an important product of the project. By evaluating various rinsing
modifications at additional companies and additional process lines, MnTAP
intends to collect the information necessary for companies to attempt a
modification to their rinsing practices.
21
-------
BIBLIOGRAPHY
Control and Treatment Technology for the Metal Finishing Industry - In-Plant
Changes. EPA 625/8-82-08.
Cushnie, George C., Jr. Electroplating Wastewater Pollution Control
Technology. Noyes Publications, Park Ridge, NJ, 1985.
Durney, Lawrence Jr., ed. Electroplating Engineering Handbook (4th Edition),
Van Nostrand Reinhold, NY, 1984.
Environmental Pollution Control Alternatives -- Reducing Water Pollution
Control Costs in the Electroplating Industry. EPA 625/5-85-016.
Foecke, Terence. Personal interview with Terence Foecke, Director, WRITAR,
Minneapolis, Minnesota, Feb. 13, 1991.
In-Process Pollution Assessment: Upgrading Metal-Finishing Facilities to
Reduce Pollution. EPA 625/3-73-546.
Kushner, Joseph B. Hater and Waste Control for the Plating Shop. Gardner
Publications, Cincinnati, OH, 1981.
Lowenheim, Frederick, Modern Electroplating. Wiley Interscience. Meltzer,
Michael, Ph.D., "Reducing Environmental Risk: Source Reduction for the
Electroplating Industry." Dissertation, UCLA.
Minnesota Technical Assistance Program (MnTAP). Quality Assurance Pro.iect
Plan for the WRITE Program With States: Evaluation of Modified Rinsing
Technologies at Micom, Inc., New Brighton, Minnesota. March 1, 1990.
Nunno, T., et. al. Toxic Waste Minimization in the Printed Circuit Board
Industry, Noyes Data Corporation, Park Ridge, NJ, 1988.
The Minnesota Technical Assistance Program (MnTAP) was created in 1984 with
support from the Minnesota Office of Waste Management (OWM). MnTAP is located
at the University of Minnesota and is a non-regulatory program designed to
help Minnesota business and industry prevent pollution at its source and
properly manage industrial wastes. These services include: telephone
assistance, on-site visits, student interns, and an information clearinghouse.
22
-------
APPENDIX
Raw Data and Calculated Drag Out Values
23
-------
Laboratory Data and Calculations for Baseline - March 12-23, 1990
number board area
date time rack # of boards In rack
In rack oqft
03/12/90 14:00 9 24 56.0
10 21 71.2
9&10 45 127.2
03/13/90 13:00 1 24 48.0
2 24 76.0
1&2 48 124
03/13/90 16:30 8 24 108.5
9 20 32.4
8&9 44 140.9
03/14/90 16:00 11 24 84.0
10 24 89.0
10&11 48 173
tank #
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Cu cone. Cu cone change In dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/eqft mg/sqtt mg/sqft
160
4.8
38
3
0.07
0.05
0.63
0.03
2.2
0.02
9
0.07
54
0.17
0.07
0.1
240
2.5
8
0.26
33800
250
7
44
240
9.1
0.14
0.11
33700
68
0.56
250
8.4
0.1
31400
205
1.7
62
380
11
0.16
0.12
30600
370
4.55
2200
18
0.36
90 21483 895 384
2.2
6
6.1 1450 32 11
0.07
0.06
67.37 15821 659 330
0.53
6.2 1476 31 12
0.08
196 46048 1919 424
1.63
8
10.83 2566 58 18
0.09
0.02
130 30768 1282 366
2.05
10 2373 49 14
0.1
dragout
volume
ml/sqft
11.3
4.7
9.8
5.0
13.5
7.6
12.0
5.7
-------
Baseline
IX)
en
number board area
date time rack # of boards in rack tank #
in rack sqft
1
03/14/90 16:30 12 24 88.5 2
13 24 84.0 3
12&13 48 172.5 4
5
6
7
8
1
03/15/90 13:00 6 24 86.0 2
5 24 96.0 3
5&6 48 182 4
5
6
7
8
1
03/16/90 16:00 12 24 126.0 2
13 25 107.5 3
12&13 49 233.5 4
5
6
7
8
1
03/19/90 16:15 7 24 84.0 2
6 24 84.0 3
6&7 48 168 4
5
6
7
8
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/sqft mg/sqft
220
2.7
70
8.3
0.19
0.08
440
7.4
86
7.8
0.06
0.07
1
0.02
100
0.17
0.05
0.15
140
1.3
88
1
0.07
0.16
29000
355
4.8
79
2400
17
0.37
0.15
38500
570
9.4
88
2100
17
0.21
0.14
31400
200
1.5
110
1800
18
0.26
0.22
31600
290
3.2
100
1300
11
0.19
0.17
135 31944 1331 361
2.1
9
8.7 2086 43 12
0.18
0.07
130 30756 1282 358
2
2
9.2 2197 46 12
0.15
0.07
199 46712 1946 371
1.48
10
17.83 4239 87 18
0.21
0.07
150 35393 1475 421
1.9
12
10 2378 50 14
0.12
0.01
dragout
volume
ml/sqft
12.4
5.0
9.3
5.0
11.8
7.6
13.3
5.9
-------
Baseline
number boa'd area
date time rack # of boards in rack tank #
in rack sqft
1
03/2O/90 12:45 1 24 64.0 2
2 24 64.0 3
1&2 48 128 4
5
6
7
8
1
03/20/90 14:30 8 24 84.0 2
7 24 107.8 3
7&8 48 191.8 4
5
6
7
8
1
03/22/90 14:15 3 24 105.0 2
4 23 74.5 3
3&4 47 179.5 4
5
6
7
8
1
03/23/90 14:00 7 24 115.5 2
8 24 85.8 3
7&8 48 201.25 4
5
6
7
8
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/scrft mg/sqft
0.03
0.37
1.1
0
340
4.4
120
3.7
0.06
0.09
91
2.5
140
2.4
0.02
0.06
300
7.9
160
4.1
0.05
31900
110
1.6
NA
9
0.1
25400
470
7
120
2400
18
0.28
0.12
34000
290
4.7
160
2200
11
0.16
0.09
38200
510
14
160
2300
18
0.25
0.1
109.97 25910 1080 405
1.23
7.9 1880 39 15
0.1
130 30896 1287 368
2.6
0
14.3 3412 71 18
0.22
0.03
199 46880 1953 446
2.2
20
8.6 2053 44 11
0.14
0.03
210 50351 2098 436
6.1
0
13.9 3313 69 16
0.2
0.1
dragout
volume
ml/sqft
12.7
6.1
14.5
7.4
13.1
4.8
11.4
6.9
-------
Laboratory Data and Calculations for Modification 1 • November 15, 1990
ro
number board area
date time rack # of boards In rack tank #
In rack sqft
1
11/15/90 08:30 2 24 80.0 2
1 20 140.0 3
1 &2 44 220 4
5
6
7
8
1
11/15/90 10:15 3 19 66.5 2
4 24 84.0 3
3&4 43 150.5 4
5
6
7
8
1
11/15/90 11:00 5 24 84.0 2
6 24 84.0 3
5&6 48 168 4
5
6
7
8
1
11/15/90 11:45 7 24 84.0 2
8 24 104.0 3
8 24 104 4
5
6
7
8
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/sqft mg/sqft
91
0.78
190
0
0
0.15
40
0.55
0.45
0
55
0.93
2
0.24
110
1.1
4
0.09
22000
150
2.5
210
2100
4.7
0.09
0.215
32400
100
2.45
2100
4.8
0.09
35700
140
1.7
1900
6.8
0.14
29700
180
2.5
900
7.4
0.13
59 14148 589 177
1.72
20
4.7 1125 26 5
0.09
0.065
60 14423 759 217
1.9
4.35 1043 24 7
0.09
85 19984 833 238
0.77
4.8 1105 23 7
-0.1
70 16636 693 198
1.4
3.4 808 34 8
0.04
dragout
volume
ml/sqft
8.0
2.1
6.7
2.9
6.7
2.7
6.7
3.2
-------
Modification 1
ro
CO
number board area
date time rack # of boards in rack tank #
in rack sqft
1
11/15/90 13:15 10 24 84.0 2
9 24 94.0 3
9&10 48 178 4
5
6
7
8
1
11/15/90 14:00 12 24 84.0 2
11 13 45.5 3
11&12 37 129.5 4
5
6
7
8
1
11/15/90 14:45 13 24 84.0 2
14 24 84.0 3
13&14 48 168 4
5
6
7
8
1
11/15/90 15:15 15 24 84.0 2
16 24 100.0 3
15&16 48 184 4
5
6
7
8
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/sqft mg/sqft
170
2
2.8
0
200
2.8
4.55
0.09
190
3.9
5.7
0.2
320
9.2
7.2
0.33
32400
280
5.1
1600
8.8
0.18
37600
270
5.2
2100
8.1
0.18
39900
275
5.5
1500
11
0.32
36100
400
9.7
2000
12
0.41
110 26352 1098 314
3.1
6 1452 30 8
0.18
70 16869 703 201
2.4
3.55 855 23 7
0.09
85 20178 841 240
1.6
5.3 1273 27 8
0.12
80 18757 782 223
0.5
4.8 1147 24 6
0.08
dragout
volume
ml/sqft
9.7
3.4
5.3
2.8
6.0
3.2
6.2
2.6
-------
Modification 1
date time
11/15/90 16:00
11/15/90 16:45
11/15/90 17:30
11/15/90 18:00
11/15/90 13:10
rack*
17
16
17&18
20
19
19&20
21
22
21 8.22
23
24
23&24
9
number
of boards
In rack
24
24
46
25
24
49
26
24
50
24
17
41
24
board area Cu cone. Cu cone change in dragout/
In rack tank # before rinse after rinse Cu cone rack
sqtt mg/l mg/l mg/l mg/sqtt
1
64.0 2
84.0 3
168 4
5
6
7
8
1
55.5 2
84.0 3
139.5 4
5
6
7
8
1
114.0 2
84.0 3
198 4
5
6
7
8
1
84.0 2 X
51.6 3 X
135.6 4
5
6
7
8
1
94.0 2
3
27800
290 350 60 14155
5.8 6.55 0.75
1400
4.9 9.2 4.3 1133
0.14 0.67 0.53
41400
290 340 50 11860
4.1 5 0.9
2300
4.5 8.7 4.2 1003
0.15 0.22 0.07
39500
170 300 130 30593
2.5 3.8 1.3
2800
4.1 8.7 4.6 1107
0.11 0.22 0.11
40600
430 430 101355
5 5
1500
5.7 9 3.3 794
0.14 0.22 0.08
32400
72 170 98 23300
022
dragout/ dragout/ dragout
board area volume
mg/sqft mg/Eqft ml/eqft
590 169 6.1
24 7 2.8
474 214 5.2
20 7 3.0
1177 268 6.8
22 6 2.3
4223 1207 |X
19 6 2.4
971 248 7.7
-------
Laboratory Data and Calculations for Modification 2 - December 10 & 11, 1990
00
o
number
date time rack # of boards
in rack
12/10/90 11:00 5 24
6 24
58,6 48
1 1 :30 7 24
8 24
7&8 48
12/10/90 12:00 9 21
10 24
9&10 45
12/10/90 13:15 11 24
12 24
11 & 12 48
12/10/90 13:20 12 24
11&12 48
board area
in rack
sqft
108.0
108.0
216
108.0
108.0
216
94.5
108.8
203.25
87.5
93.5
181
93.5
181
tank*
5
6
7
5
6
7
1
2
3
4
5
6
7
B
1
2
3
4
5
6
7
8
1
2
3
1
2
3
Cu cone. Cu cone change in dragout/ dragout/
before rinse after rinse Cu cone rack board
mg/l mg/l mg/l mg/sqft mg/sqft
3.8
0
7
0.2
250
8
4.5
0.08
140
3.3
1.8
0
240
5.2
140
3.3
2300
9.3
0.17
2100
14
0.32
36200
340
11
2000
10.4
0.22
33200
240
5.2
2300
6.4
0.06
33200
330
8.1
33200
330
8.1
5.5 1332 28
0.17
7 1673 35
0.12
90 21669 1032
3
5.9 1419 32
0.14
100 23743 989
1.9
4.6 1095 23
0.06
90 21646 902
2.9
190 45764 953
4.8
dragout/ dragout
area volume
mg/sqft ml/sqft
6 2.6
B 3.2
229 6.3
7 2.9
271 8.2
6 2.5
232 7.0
253 7.6
-------
Modification 2
number board area
date time rac'< # °' boards in rack tank #
in rack sqft
1
12/10/90 14:45 13 24 108.5 2
14 24 119.0 3
13&14 48 227.5 4
5
6
7
8
1
12/10/90 14:50 14 24 119.0 2
3
13&14 48 227.5
1
2
3
1
12/11/90 09:30 4 21 59.5 2
3
4 21 59.5 4
5
6
7
8
1
12711/90 10:15 5 24 108.0 2
6 11 49.5 3
5&6 35 157.5 4
5
6
7
8
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/sqft mg/sqft
54
1.4
0.95
0
170
3.5
54
1.4
160
4.7
7.9
0
120
2.9
6.5
0.04
31100
170
3.5
2000
7.95
0.08
31100
290
7.4
31100
290
7.4
32950
220
4.7
2200
10
0.13
32900
200
7.2
2300
9.5
0.14
116 27517 1147 254
2.1
7 1664 35 7
0.08
120 28869 1203 243
3.9
236 56852 1184 250
6
60 13980 666 235
0
2.1 524 25 9
0.13
80 19642 818 182
4.3
3 728 21 5
0.1
dragout
volume
ml/sqft
8.2
3.0
7.8
8.0
7.1
3.7
5.5
1.9
-------
Modification 2
Co
no
number board area
date time rack # of boards in rack
In rack sqft
12/11/90 11:00 7 24 84.0
8 24 84.0
7&8 48 168
12/11/90 11:45 9 24 80.0
10 24 64.0
98,10 48 144
12/11/90 12:15 11 25 87.5
12 26 91.0
11&12 51 178.5
12/11/90 12:15 11 25 87.5
12 26 91.0
tank*
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
5
6
7
5
6
7
Cu cone. Cu cone change in dragout/ dragout/ dragout/
before rinse after rinse Cu cone rack board area
mg/l mg/l mg/l mg/sqft mg/sqft mg/sqft
135
5.4
4.2
0
190
6.4
9.5
0.12
240
9.3
4.1
0.12
4.1
0.12
6.7
0.19
36000
230
7
2300
8
0.09
33300
255
8.7
2200
13
0.31
35700
320
11
2500
9.9
0.32
2500
6.7
0,19
2500
9.9
0.32
95 22508 938 268
1.6
3.8 914 19 5
0.09
65 15681 653 196
2.3
3.5 867 18 6
0.19
80 19036 761 218
1.7
5.8 1409 28 8
0.2
2.6 622 25 7
0.07
3.2 782 30 9
0.13
dragout
volume
ml/sqft
7.4
2.3
5.9
2.5
6.1
3.3
3.0
3.6
notes:
03/20/90
11/15/90
12:45 The sample from tank #5 was destroyed in a laboratory accident.
18:00 Tank #2 & tank #3 were not sampled before the racks were rinsed - Sampling error.
Dragout volumes could not be calculated.
-------
CO
CO
Dragout and Withdrawal/Drain Time
Micro Etch Baseline
04/23/91
dragout withdrawal
DATE
03/12/90
03/13/90
03/13/90
03/14/90
03/14/90
03/15/90
03/16/90
03/19/90
03/20/90
03/20/90
03/22/90
03/23/90
standard
TIME
14:00
13:00
16:30
16:00
16:30
13:00
16:00
16:15
12:45
14:30
14:15
14:00
RACK#
9
1
8
11
12
6
12
7
1
8
3
7
total
average
deviation(n-l)
range
9.3
volume
ml/sqft
11.3
9.8
13.5
12.0
12.4
9.3
11.8
13.3
12.7
14.5
13.1
11.4
145.2
12.1
1.5
14.5
time
(s)
1
1.5
2.9
1.3
1.5
3.2
2.7
1.8
1.2
1
1.7
1
20.8
1.7
0.8
drain
time
(s)
3.4
5.5
2.7
7.6
6.2
3.2
4.3
1.2
1.5
1.3
1.5
2.3
40.7
3.4
2.1
total
time
(s)
4.4
7
5.6
8.9
7.7
6.4
7
3
2.7
2.3
3.2
3.3
61.5
5.1
2.3
-------
Dragout and Withdrawal/Drain Time
Electroless Copper Baseline
04/23/91
DATE TIME RACK #
03/12/90 14:00 9 & 10
03/13/90 13:00 1 & 2
03/13/90 16:30 8 & 9
03/14/90 16:00 10&11
03/14/90 16:30 12 & 13
03/15/90 13:00 5 & 6
03/16/90 16:00 12 & 13
03/19/90 16:15 6 & 7
03/20/90 12:45 1 & 2
03/20/90 14:30 7 & 8
03/22/90 14:15 3 & 4
03/23/90 14:00 7 & 8
Total
Average
Standard deviation (n-1)
Range 4.7
dragout
volume
ml/sqft
4.7
5.0
7.6
5.7
5.0
5.0
7.6
5.9
6.1
7.4
4.8
6.9
71.7
6.0
1.1
7.6
Withdrawal Time
(seconds)
first second
1
1.6 2.2
8.7 0.5
1 1
1.3 0.8
1.9 1.6
3.7 1.1
1.6 1.2
0.7 1.3
1.7 1.4
2.2 1.5
1.8 1.3
26.2 14.9
2.4 1.2
2.2 0.4
0.5 8.7
ave. 1.8
stds. 1.6
Drain Time
(seconds)
first second
9.7
4.7 8.3
6.3 0.8
2.7 9.8
5.2 7.5
4.1 5.5
1.4 2.9
4.4 10.2
7.6 4
3.3 3.8
4.8 6.5
2.9 4
47.4 73.0
4.3 6.1
1.7 3.1
0.8 10.2
5.2
2.6
Total Time
(seconds)
first second
10.7
6.3 10.5
15 1.3
3.7 10.8
6.5 8.3
6 7.1
5.1 4
6 11.4
8.3 5.3
5 5.2
7 8
4.7 5.3
73.6 87.9
6.7 7.3
3.0 3.2
1.3 11.4
7.0
3.1
-------
CO
en
Dragout and Withdrawal/Drain Time
Micro Etch - Modification 1
04/24/91
dragout withdrawal
DATE
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
Standard
TIME
08:30
10:15
11:00
11:45
13:10
13:15
14:00
14:45
15:15
16:00
16:45
17:30
Average
Deviation
Range
RACK#
2
3
5
7
9
10
12
13
15
17
20
21
Total
(n-1)
5.2
volume
ml/sqft
8.0
6.7
6.7
6.7
7.7
9.7
5.3
6.0
6.2
6.1
5.2
6.8
81.0
6.7
1.2
9.7
time
(s)
13.6
14.6
14.8
14.5
14.8
14.8
14.4
16.0
15.0
15.6
15.6
163.7
14.9
0.7
drain
time
(s)
1.9
3.0
2.2
1.6
4.6
3.0
2.4
1.8
3.0
1.4
2.4
27.3
2.5
0.9
total
time
(s)
15.5
17.6
17.0
16.1
19.4
17.8
16.8
17.8
18.0
17.0
18.0
191.0
17.4
1.1
-------
Dragout and Withdrawal/Drain Time
Electroless Copper - Modification 1
04/23/91
DATE
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
11/15/90
Standard
TIME
09:30
11:15
12:00
13:00
14:15
15:00
15:30
16:15
17:00
17:42
18:30
19:00
Average
RACK#
1&2
3&4
5&6
8
9&10
11&12
13&14
15&16
17&18
19&20
21&22
23&24
Total
Deviation(n-l)
Range
2.1
dragout
volume
ml/sqft
2.1
2.9
2.7
3.2
3.4
2.8
3.2
2.6
2.8
3.0
2.3
2.4
33.49
3.04
0.4
3.4
Withdrawal
(seconds)
first
14.9
13.8
13.5
13.4
13.1
13.2
14.9
13.8
14.1
14.0
14.1
152.8
13.9
0.6
13.1
ave.
stds.
Time
second
14.3
13.5
14.8
13.2
13.1
13.4
13.4
14.2
13.8
15.4
13.5
13.2
165.8
13.8
0.7
15.4
13.9
0.7
Drain
Time
(seconds)
first
3.7
2.3
1.4
2.0
4.3
2.2
1.1
1.6
1.1
2.6
2.1
24.4
2.2
1.0
1.1
second
8.7
2.2
4.8
6.7
1.3
2.3
3.0
4.5
6.6
5.9
2.4
1.9
50.3
4.2
2.4
8.7
3.2
2.1
Total
Time
(seconds)
first
18.6
16.1
14.9
15.4
17.4
15.4
16.0
15.4
15.2
16.6
16.2
177.2
16.1
1.1
14.4
second
23.0
15.7
19.6
19.9
14.4
15.7
16.4
18.7
20.4
21.3
15.9
15.1
216.1
18.0
2.8
23.0
17.1
2.3
CO
CTi
-------
GO
Dragout and Withdrawal/Drain Time
Micro Etch - Modification 2
04/24/91
dragout withdrawal drain
DATE
12/10/90
12/10/90
12/10/90
12/10/90
12/10/90
12/10/90
12/10/90
12/11/90
12/11/90
12/11/90
12/11/90
12/11/90
Standard
TIME
12:00
13:15
13:15
13:20
14:45
14:45
14:50
09:30
10:15
11:00
11:45
12:15
Average
RACK#
9
11
11&12
12
13
13&14
14
4
5
7
9
11
total
deviation(n-l)
Range
5.5
volume
ml/sqft
6.3
8.2
7.6
7.0
8.2
7.8
8.0
7.1
5.5
7.4
5.9
6.1
85.17
7.1
0.9
8.2
time
(s)
4.5
4.5
4.3
2.1
5.6
4.3
4.4
4.7
4.2
4.1
42.70
4.3
0.9
time
(s)
13.5
11.4
11.1
11.6
11.8
11.8
11.8
12.2
13.7
12
120.90
12.1
0.9
total
time
(s)
18
15.9
15.4
13.7
17.4
16.1
16.2
16.9
17.9
16.1
163.60
16.4
1.3
-------
GO
oo
JO
z
n
z
H
2
Z
f>
O
Dragout and Withdrawal/Drain Time
Electroless Copper - Modification 2
04/24/91
DATE
12/10/90
12/10/90
12/10/90
12/10/90
12/10/90
12/11/90
12/11/90
12/11/90
12/11/90
12/11/90
12/11/90
12/11/90
Standard
TIME
11:00
11:30
12:00
13:15
14:45
09:30
10:15
11:00
11:45
12:15
12:20
12:25
RACK#
5&6
7&8
9&10
11&12
13&14
4
5&6
7&8
9&10
11
12
11&12
total
Average
deviation(n-l)
Range 1.9
dragout
volume
ml/sqft
2.6
3.2
2.9
2.5
3.0
3.7
1.9
2.3
2.5
3.0
3.6
3.3
34.47
2.9
0.5
3.7
Withdrawal
(seconds)
first
4.9
4.0
3.5
3.9
4.2
4.3
4.4
4.9
3.5
37.6
4.2
0.5
3.5
ave.
stds.
Time
second
4.4
4.8
4.2
4.1
4.9
4.2
4.0
4.9
4.4
4.4
44.3
4.4
0.3
4.9
4.3
0.4
Drain Time
(seconds)
first second
11.2
11.4
11.6
12.1
11.8
12.4
11.9
11.1
11.5
105.0
11.7
0.4
11.1
11.2
11.8
12.8
16.4
11.8
11.3
11.9
11.4
11.1
11.6
121.3
12.1
1.6
16.4
11.9
1.2
Total Time
(seconds)
first second
16.1
15.4
15.1
16.0
16.0
16.7
16.3
16.0
15.0
142.6
15.8
0.6
15.0
15.6
16.6
17.0
20.5
16.7
15.5
15.9
16.3
15.5
16.0
165.6
16.6
1.5
20.5
16.2
1.2
------- |