Printed Wiring Board Industry: Description of Project
1.1 Overview of DfE PWB Project
This report presents an analysis of the results of a pollution prevention and control survey for printed wiring board (PWB) manufacturers. The survey was conducted by CAI Engineering, with assistance from the Institute for Interconnecting and Packaging Electronic Circuits. The survey results were analyzed and this report was prepared by CAI Engineering, under a subcontract to Microelectronics and Computer Technology Corporation. The Design for the Environment Printed Wiring Board Project stakeholders provided significant input to the final report. The work was funded by grant #X 823856-01-0 under EPA's Environmental Technology Initiative program.
The DfE PWB project is a voluntary cooperative partnership with EPA, industry, and other interested parties that promotes implementation of environmentally beneficial and economically feasible alternatives by PWB manufacturers. The ultimate goal of this project is to help the PWB industry increase efficiency and reduce risk in the PWB industry by giving individual PWB manufacturers the information they need to make informed decisions that fit their particular needs. The initial focus of the project is to evaluate processes or technologies for "making holes conductive" (MHC), the process of depositing a conductive surface in drilled through-holes prior to electroplating. In support of these efforts, the DfE project is conducting a Cleaner Technologies Substitutes Assessment (CTSA) of several alternative MHC processes and tests are being conducted to test the performance of alternative processes. The goal of the CTSA and testing phase is to offer a complete picture of the trade-offs between the potential environmental and health risks, performance, and costs of alternative processes so that PWB manufacturers can make informed business decisions that fit their particular situations. The CTSA will focus on alternatives such as electroless copper, graphite-based, carbon-based, and palladium-based processes.
1.2 Purpose of the Survey
The pollution prevention and control survey was performed to gather and organize information about the current state of environmental technology and practices for this industry segment. The focus of the survey was on determining the types of technologies and alternative processes used, the extent of their use, key factors with regard to implementation, including costs, and their success and failure rate. Pollution prevention and control technologies covered by the survey include substitute raw materials and manufacturing processes, reuse and recycle technologies, procedural changes, and innovative treatment/disposal methods that reduce chemical use or water use and/or prevent the production of hazardous waste material and its release to the air, water, or land.
The survey results are for the use of all those associated with the printed wiring board manufacturing industry. PWB manufacturers can use the results of the survey to compare their own manufacturing operations to those of the survey respondents. Using the survey results, manufacturers can evaluate how their operations compare in terms of chemical and other raw material usage rates, water use, waste generation, technology level used, and other key factors. The results also show which treatment, recovery and bath maintenance technologies have been most successful and the costs for purchasing and operating these technologies, trends in chemical substitution, the identification of regulated pollutants, sludge generation rates, off-site sludge recovery and disposal options, and many other pertinent topics. In addition to the manufacturing segment, the results will also be very useful to companies that service the PWB industry including engineering firms, chemical suppliers, manufacturers/vendors of pollution prevention and control equipment, and off-site recycling and disposal sites.
1.3 Survey Procedures
The survey of PWB manufacturing facilities was accomplished using a mailed questionnaire. To ensure that the survey adequately addressed the key production processes and pollution prevention methods, a draft form was prepared and reviewed by various industry participants, EPA, and other interested parties. The questionnaire was then tested by surveying a selected group of five PWB facilities. Based on these responses, the survey form was revised. The final survey form (Appendix A) was then distributed by IPC to all IPC PWB manufacturing facility members (approximately 400).a The survey form covers eight major areas:
- Facility and Point of Contact Identification. In order to maintain confiden-tiality, this portion of the survey form was kept separate from other portions of the form. Used only in the event that clarification to responses was needed, a procedure was employed that prevented anyone from connecting responses to their originator.
- Facility Characterization. Requests data concerning facility size, product type, base materials used, process capabilities, and technology level.
- Wastewater Discharges. Requests data concerning the type of discharge (i.e., direct, indirect, zero), flow rates, discharge limitations, compliance problems, and costs for water and sewer use.
- Process Data. Requests data concerning various elements of the manufacturing process, including etch resist, inner- and outer-layer etching, through-hole metalization, oxide, etchback/desmear, solder mask, and chemical usage.
- Recovery, Recycle, or Bath Maintenance Technology. Requests data concerning pollution prevention technologies, including costs, savings, labor needs, maintenance requirements, residuals generation, and other important information.
- Pollution Prevention Methods. Requests data concerning pollution preven-tion (P2) methods used by the facilities for improving operating procedures, reducing water use, preventing the loss of chemicals, and making other improvements.
- End-of-Pipe Treatment. Requests data concerning the type of treatment processes used, capital and operating costs, sludge generation, and compliance problems.
- Identification of Problems and Needs. Requests data concerning environ-mental and occupational health challenges, technology needs, and information needs.
The recipients of the questionnaire were given approximately three weeks to complete and return the form. An "800 hotline" was established at the outset of the survey to handle recipients' questions. To increase the response rate, non-respondents were contacted by fax communications at the end of the three week response period and given additional time to complete the form.
Recipients of the questionnaire were clearly notified that all information and data that they supplied in survey form are confidential and that any use or publication of the data will not identify the name or location of the respondent company or the individual completing the form. The source of each response is not known by CAI Engineering or other project participants.
Most of the data collected during this project are summarized in tables presented in this report. The basic repository for the storage and use of questionnaire respondent raw data is a database developed using a commercial software package (Microsoft Access®). The database file is available to the public in its native format, and utilization therefore requires a licensed copy of the original program.
Some tables presented in this report contain the names of manufacturers and/or commercial products or services used by respondents of the survey. Mention of companies or commercial products or services is not intended to constitute endorsement for use.
1.4 Overview of Results
The survey form was mailed to approximately 400 PWB manufacturing sites (there are a total of approximately 750 in the U.S.). A total of 40 responses were received (i.e., 10% response rate). Based on dollar sales, the 40 responses represent approximately 17% of the total U.S. PWB production (ref. 2).
This report organizes and presents the majority of the data collected during the PWB survey project; however, it does not contain an exhaustive evaluation of those data. The detailed evaluation of the data will be conducted in a subsequent project and the results will be published separately.
The following are some important findings from the survey:
- The survey respondents span the range of PWB facilities found in the U.S. in terms of production rates, but are more representative of the mid- to larger-sized facilities. This circumstance should be considered with any use or interpretation of the data.
- Based on the survey results, it is apparent that the electroless copper process is still entrenched as the predominate method of making holes conductive. Eighty-six (86%) percent of the survey respondents are still using electroless copper on all or nearly all of their product. Fourteen (14%) percent indicated they are using palladium-only systems on all of their product and only one respondent is using the graphite-based system, while another was evaluating it. No respondents reported using the carbon-based system and one respondent is evaluating an electroless nickel system.
- The range of water use among respondents is very large and there is evidence that some facilities have significantly better water use practices than other facilities. One reason for high water use variability among PWB manufacturers appears to be variable water and sewer use charges paid by the respondents. A relationship exists between the adjusted production-based flow rates and the cost of water and sewer use. For facilities that have very high combined water and sewer costs, the adjusted production-based flow rates are very low. Alternatively, facilities with very low combined water and sewer costs have high adjusted production-based flow rates.
- Low water use rates have been achieved by some survey respondents through the implementation of simple water conservation techniques and/or by using technologies such as ion exchange that recycle water. The lowest production-based flow rate among survey respondents was achieved without the use of any sophisticated recycling technology. Rather, they use flow controllers, rinse timers, and reactive or cascade rinsing. The data also indicate that facilities that have implemented the ion exchange technology within their processes have a lower average flow rate than those that have not implemented this technology.
- The data indicate that the use of water conservation methods does not always result in low water use. The four facilities with the highest production-based flow rates do not use ion exchange recycling, but they all indicated that they employ counterflow rinsing, plus some other methods of water conservation. In such cases, it is probable that water is simply being wasted by having unnecessarily high flow rates in their rinse tanks.
- The survey data show that the majority of the respondents are indirect dischargers (i.e., facilities that discharge process wastewaters to a publicly owned treatment works or POTW). This is especially true for the small to mid-sized PWB manufacturing facilities. Seventy-seven percent of all respondents indicated that they are indirect dischargers, whereas 94% of the shops with an annual production rate below 300,000 board ft2 are indirect dischargers.
- The data indicate that the majority of respondents (63%) must meet local wastewater discharge limitations that are more stringent than the Federal standards. Very few respondents reported any wastewater compliance difficulties.
- One-half of the survey respondents have a formal pollution prevention plan. Most facilities have implemented common pollution prevention methods and procedures.
- Three-quarters of the survey respondents have implemented recycle, recovery, or bath maintenance technologies that conserve water and/or prevent pollution. The most common of these technologies is the use of porous pots for maintenance of permanganate desmear, ion exchange for water recycle, and electrowinning for metal recovery and reuse. Very few advanced technologies such as diffusion dialysis, membrane electrolysis, or solvent extraction are used.
- Off-site recycling is a commonly used method for PWB manufacturers to manage spent etchant solutions and wastewater treatment sludges.
- The most common regulated pollutants found in PWB wastewater are copper, lead, nickel, silver, and total toxic organics (TTO).
- Two basic wastewater treatment configurations are present at the respondent's facilities: conventional metals precipitation and ion exchange systems. Sixty-one percent (61%) of the respondents reported having conventional metals precipitation systems. Thirty-three percent (33%) of the respondents reported using ion exchange as their basic waste treatment technology and 6.1% installed ion exchange in conjunction with conventional metals precipitation units.