Proceedings of the Sixteenth International Electronics Manufacturing Technology Symposium (IEMT),
Austin, TX, Oct. 1996.

Cost and Environmental Metrics for a High Density Laminate Technology

C. Murphy and P. Sandborn


Printed wiring boards (PWBs), including laminate substrates for MCM-L's, are used to interconnect components in most electronic products. Yet the amount of waste generated in the fabrication of these substrates significantly exceeds the amount of material in the final fabricated substrate, with a large portion of the waste considered hazardous. In a typical PWB, it is estimated that up to 5 times more waste than product (by weight) is generated during the board production process. Therefore, it is becoming increasingly important that PWB manufacturers consider the waste stream created when boards are fabricated, the costs associated with the waste stream and the potential impact on the environment

Design for environment (DFE) is a collection of design practices aimed at assessing and creating "eco-efficient" and "eco-economic" products and processes. THe objective of DFE is to facilitate the systematic consideration of design performance with respect to environmental, health, and safety objective over the full product life cycle. Successful design for environment requires the coordination of many design and data management activities including life cycle assessment (material and waste inventory and impact analysis) and detailed cost modeling to assess the economic impacts of design and manufacturing alternatives concurrent with environmental assessment.

Unfortunately, environmental impact is not a system attribute that can be easily modified after the products design is completed. Therefore if the environmental impact of product manufacturing is to be considered, it must be treated during system planning and synthesis activities when designers have the flexibility to make major design changes without significantly effecting the time-to-market for the product. In an ideal design flow, DFE activities must be part of a broader interdisciplinary tradeoff analysis and the concurrent engineering process.

This study focuses on the fabrication of multilayer printed wiring boards. Fabrication of multilayer PWBs typically includes common processes and materials, such as epoxy glass laminate with plated through holes for side-to-side connection. However, there are emerging technologies aimed chiefly at improving performance and reducing cost. Although not necessarily design to do so, these new processes and/or materials have the potential to have a positive impact on environmental metrics as well. Many overall product volume (either layer count or size). THis in turn decreases the amount of waste, water, and energy usage associated with the manufacture of the board. Several of these processes are additive or semi-additive, which eliminates waste associated with removal (subtraction) of large areas of unwanted material during etch and strip processes.

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