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Direct metallization has been gaining attention in the printed wiring board (PWB) industry as an environmentally preferable alternative to electroless copper. Even though many PWB manufacturers are currently using these alternatives, there is still a lack of available information on successfully implementing them. Some of the best sources of information about alternative technologies for Making Holes Conductive (MHC) are those PWB manufacturers who have actually installed and used the direct metallization systems under real-world operating conditions. By sharing information, PWB manufacturers can benefit from others' experiences with the relatively new technologies. This report details the specific experiences of these companies, along with their recommendations for successful implementation.

This guide presents first-hand accounts of the problems, solutions, time, and effort involved in implementing alternative MHC technologies. The information presented is based on telephone interviews with PWB manufacturers currently using these technologies, manufacturers who have used and discontinued these technologies, and the vendors of these alternative technologies. When a respondent is directly cited, their comments appear in quotes. With the information from these interviews, manufacturers considering a switch to an alternative technology can benefit from the lessons learned by those who have already made the change.

Twenty PWB manufacturers and seven vendors were interviewed. Appendix A provides background information on these facilities, such as annual production, types of boards produced, highest aspect ratio normally run, and conveyorized (horizontal) or non-conveyorized (vertical) configuration.

Carbon, graphite (two types), palladium (five types), and conductive polymer technologies are discussed in this guide. Each section begins with a description of the technology, presents a flow chart of the technology's typical process steps, and provides a summary of the interviews. This document was developed as part of the Design for the Environment (DfE) Printed Wiring Board Project. The DfE PWB Project is a voluntary, cooperative partnership which identifies and assesses environmentally beneficial technologies and practices for the PWB industry. Project partners include the U.S. Environmental Protection Agency (U.S. EPA), the printed wiring board industry, Microelectronics and Computer Technology Corporation (MCC), the University of Tennessee Center for Clean Products and Clean Technologies, the Institute for Interconnecting and Packaging Electronic Circuits (IPC), and other stakeholders. The primary focus of the project has been the evaluation of environmentally preferable MHC technologies. Quantitative performance testing (both electrical and mechanical), risk characterizations, and cost analyses were conducted on a comparative basis for several MHC technologies, including electroless copper. The results of these analyses will be presented in a Cleaner Technologies Substitute Assessment (CTSA) report.

Throughout the document, the facilities interviewed are not mentioned by name. Instead, each company has been given a code, Facility A, Facility B, etc. It was the opinion of the project participants that using the actual facility names might distract the reader from the information presented on the technologies. However, the information in Appendix A will assist the reader in understanding some of the circumstances governing production at each of the facilities interviewed. This information includes the surface square feet produced annually, the types of PWBs produced, and the highest aspect ratio run for each facility.

It should be noted that mention of trade names in this report does not constitute endoresement or recommendation for use. Instead, the reader is encouraged to contact the individual companies for more information on their products.

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