FOR
THE
                                                                           PRINTED WIRING BOARD CASE STUDY 1
A Cooperative Project
between the
U.S. Environmental
Protection Agency
and PWB
Manufacturers
Nationwide
                                 PRINTED WIRING  BOARD
                                       CASE   STUDY   1
                                            Pollution
                                          Prevention
                                      Work  Practices
                                      The Design for the Environment (DfE)
                                      Printed Wiring Board Project is a vol-
                                      untary, cooperative effort between the
                                 printed wiring board (PWB) industry, the
                                 U.S. Environmental Protection Agency (EPA),
                                 and other stakeholders dedicated to helping
                                 PWB manufacturers find cost-effective ways
                                 to incorporate environmental concerns into
                                 business decisions. To help PWB manufac-
                                 turers improve environmental performance,
                                 the DfE project is developing a series of case
                                 studies highlighting industry-specific pollu-
                                 tion prevention information.
                                      Successful pollution prevention focuses
                                 on reducing or eliminating pollution at the
                                 source through changes in materials,
                                 processes, practices, or products. Source
                                 reduction is at the top of the pollution pre-
                                 vention hierarchy, and is preferred by EPA
                                 over closed-loop recycling,  treatment,  and
                                 disposal. As specified in the Pollution Pre-
                                 vention Act, EPA prefers that companies
                                 investigate recycling and treatment only after
                                 every attempt has been made to implement
                                 source reduction options.
             Implementing viable pollution preven-
        tion alternatives can result in economic as well
        as environmental benefits for your manufac-
        turing operation. This case study, the first of a
        series, focuses on improved work practices
        and minor process changes that PWB manu-
        facturers have found reduced their chemical
        and water use, lowered workplace chemical
        exposures, or reduced waste generation and
        resulting disposal and compliance costs. These
        changes have reduced the environmental
        impact of the facilities' manufacturing process-
        es and have  cut costs at the same time. For
        example, after implementing some simple
        water conservation measures, one PWB manu-
        facturing plant with a throughput of 1,000
        boards per week was able to save over
        850,000 gallons of water per year. The $250
        implementation cost of purchasing and
        installing the flow reducers used to  achieve
        these savings led to an extremely short pay-
        back period of only two months.
             As you think about the production
        processes and work practices in your plant,
        this case study may give you some new ideas
        for preventing pollution in your facility. There
        are many more techniques that PWB manufac-
        turers have used to prevent pollution than
        space available in this publication allows. In
        addition, many manufacturers have  invested
           Pollution Prevention Hierarchy
                                                                                               July 1995

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          Pollution
        Prevention
    Work Practices
     The Design for the Environment (DfE)
     Printed Wiring Board Project is a vol-
     untary, cooperative effort between the
printed wiring board (PWB) industry, the
U S Environmental Protection Agency (EPA),
and other stakeholders dedicated to helping
PWB manufacturers find cost-effective ways
to incorporate environmental concerns into
business decisions. To help PWB manufac-
turers improve environmental performance,
the DfE project is developing a series of case
studies highlighting industry-specific pollu-
tion prevention information.
      Successful pollution prevention focuses
 on reducing or eliminating pollution at the
 source through changes in materials,
 processes, practices, or products. Source
 reduction is at the top of the pollution pre-
 vention hierarchy, and is preferred by EPA
 over closed-loop recycling, treatment, and
 disposal.  As specified in the Pollution Pre-
 vention Act, EPA prefers that companies
 investigate recycling  and treatment only after
 every attempt has been  made to implement
 source reduction options.
  and have cut costs at the same time. For
example, after implementing some simple
"uer conservation measures, one PWB manu-
facturing plant with a throughput of 1,000
boards per week was able to save over
850 000 gallons of water per year. The ^U
implementation cost of purchasing  and
installing the flow reducers used to achieve
these savings led to an extremely short pay-
back period of only two months.
      As you think about the production
 processes and work practices in your plant,
 this case study  may  give you some new ideas
 for preventing pollution in your facility. There
 are many more techniques that PWB manufac-
 turers have used to  prevent pollution than
 space available in this publication allows. In
 addition, many manufacturers have  invested
     Pollution Prevention Hierarchy
                                                                 July  1995

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in more capital intensive changes, such as on-site etchant
regeneration (the focus of Case Study #2) or an ion
exchange/electrowinning system for metals recovery from
wastewater, which can significantly reduce waste generation.
Getting Started
      The most successful pollution prevention programs are
developed as an integral part of a facility's decision-making
process, where the opportunities to prevent pollution are
considered with each decision to install new equipment, to
make process changes, or to purchase new chemicals.
   The Benefits of Preventing Pollution  Include
   Reductions in:

    Raw materials use, exposures, and costs
    Waste generation and disposal costs
    Regulatory compliance costs
    Treatment costs
    Transportation risks and costs
      In planning a pollution prevention program, it is essen-
tial to first obtain the full support of management and to
define the goals of the program. Next, examine each step of
your manufacturing process and identify the raw materials
used, wastes generated, potential occupational exposures,
and environmental releases. This assessment will allow you to
take a comprehensive look at your process and to prioritize
and select areas where pollution prevention and cost savings
are most feasible and most easily accomplished.
      Once the most promising opportunities have been
implemented, evaluations of the project engineering, equip-
ment design, and performance should be conducted.
      The process does not end after implementation of the
selected opportunity. Pollution prevention is an efficient
way of doing business because there is continuous evalua-
tion of pollution prevention opportunities in working
toward the goal of eliminating risk to workers and the envi-
ronment, while maintaining or improving product quality
and process efficiency.

Preventing Pollution

      While the materials used, releases, exposures, and
wastes generated will vary from one facility to another, the
pollution prevention ideas presented  in this case study have
been successfully implemented under a variety  of operating
conditions. This case study concentrates on relatively simple
changes that PWB manufacturers have found to be helpful in
reducing chemical losses, increasing bath life, conserving
water, reducing sludge volume, or recovering materials that
otherwise  would have  been disposed.
      By reducing dragout between the process baths and
the rinsewater, both the amount of chemical removed from
the bath and the amount of chemical added to the rinsewa-
ter can be reduced. The following options will help to
reduce dragout:

   Withdraw racks at a slower rate: lengthen dragout time to
   allow more chemical to drip back to the process tank.
   Tilt racks at an angle to allow dragout chemicals to collect
   and drain back into the tank.
   Install drainboards  between process and rinse tanks.
   Drainboards will minimize spillage between tanks. By
   sloping the drainboards away from rinse tanks, dragout
   chemicals drain back into the process tank.
       WORK
       PIECE
                PROCESS
                 TANK
   Using a cam, add a slight bump at the end of the rack
   withdrawal stroke to shake excess chemical back into
   the bath.
   Install an under-rack tray that travels with the rack from
   one tank to the next and empties dragout back into
   the tank.
      In addition to reducing dragout, process bath chemi-
cals and replenisher can be conserved by maximizing the
useful life of process baths. Sludge generated from treatment
of spent baths will also be reduced with the lengthening of
bath life.

   Useful bath life can be maximized by understanding the
   bath conditions through monitoring. With some process-
   es such as electroless lines, cupric chloride etching, and
   ammoniacal etching, continuous monitoring (pH, con-
   ductivity,  specific gravity, colorimetric, or on-line titra-
   tion) allows the operator to maintain consistent,
   optimum  conditions. Other types of baths (e.g., copper
   plating and tin-lead plating) can be maintained through
   periodic monitoring.
                                                                                        July  1995

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   Facilities that currently send bath samples off-site for test-
   ing may find it cost-effective to test the bath chemistry
   on-site. This allows for improved control of process baths
   through shorter turnaround times between  the bath mea-
   surement and the bath adjustment. The capital required
   for equipment and personnel may  be justified through the
   savings associated with improved process control and
   reduced fees for laboratory testing.

   Baths that require dumping due to particle  build-up, such
   as the resist build-up in the stripper for photoresist, can
   be filtered to increase the bath life.

   Use rinse water as make-up to top off the bath.

   Using a ''drain and fill" system as an alternative to a "feed
   and bleed" system for process bath replenishment can
   reduce chemical use while still allowing for in-process
   replenishment. The drain and fill system automatically
   removes a measured volume of the spent process solution
   (draining) by lowering the level slightly in the process tank
   and then replacing (filling) the removed solution with
   fresh chemical without interrupting production. Unlike a
   feed and bleed system where a  portion of the fresh solu-
   tion is bled with the spent solution, the drain and fill sys-
   tem does not waste fresh solution. This technology  can be
   applied to the feed and bleed process in photoresist devel-
   oping and photoresist stripping  operations,  electroless cop-
   per bath growth, and ammoniacal etchant replenishment,
   as well as to rinse tanks where water use can be reduced.
                                     Oft
      By taking steps to prevent copper build-up on your
plating racks, you can reduce the amount of stripping solu-
tion needed, thereby reducing the amount of plating sludge
generated.
   One facility converted to polyethylene racks on their elec-
   trolytic plating lines and reduced the amount of strip-
  ping solution needed (and spent stripper) by 75%.
   Plating rack design and material choice can reduce cop-
    per build-up. Using polyethylene-coated plating racks in
    the electrolytic copper plating lines can significantly
    reduce copper build-up.

   Some facilities have found they can easily scrape the cop-
   per build-up from racks with a knife instead of chemical-
   ly removing it. This option may only be feasible for
   smaller facilities.

   Check racks periodically for wear. Replace insulation
   where it has worn out and, when necessary, rebuild and
   recoat racks.
                                    from
      Process chemicals lost through evaporation contribute
to your environmental releases and increase your raw materi-
al costs.

   Verify that your ventilation and air circulation system is
   engineered to achieve an optimal balance between
   increasing ventilation to reduce employee exposure and
   decreasing ventilation to reduce chemical losses and
   releases to the environment through evaporation.

   Float polypropylene balls on plating baths to reduce
   evaporation from process tanks.  The success of this
   technique depends on the type of bath and the tank
   configuration.
      Improvements in your rinsing efficiency can reduce the
amount of water required for rinsing while reducing the
amount of wastewater sent to treatment.

   Install flow controls. For example, use spray rinsing in the
   first rinse tank or use flow restrictors to reduce the quanti-
   ty of water used. Additionally, installing contact switches
   automatically turns off the fresh water supply when the
   rinse is not in use.

   Use a countercurrent rinse configuration.

   Use an evaporator to concentrate the wastewater from the
   first tank after the copper plating tank and return the cop-
   per to the plating tank as a make-up.

   Install a rinse tank controller to measure conductivity
   dynamically. As acidic rinsewater indicates contamination,
   a conductivity sensor provides information on the cleanli-
   ness of the rinsewater, and can be set to trigger the flow
   of fresh water only when necessary.

   Install turbulence devices, such as mixers or agitators to
   increase contact between the rinse water and the board.
   Air agitation or workpiece agitation can also improve
   rinse efficiency.
      Workpiece
      Movement
                      Work
                     Product
         1
                       T
         Process
          Tank
Rinse
          Rinse
                    Rinse
                                              '
                                            T
             Effluent to recycle,
             resource recovery
               or treatment
                      Rinse
                      Water
                     Influent
                                                                                           July 1995

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