Medical Electronics Symposium Conference Proceedings


PROCESS CONSIDERATIONS IN TRANSITIONING RoHS-EXEMPT ELECTRONIC ASSEMBLIES TO LEAD-FREE PROCESSES

Authors: Chrys Shea and Tim Luke
Company: ALPHA – A Cookson Electronics Company
Date Published: 5/3/2007   Conference: Medical Electronics Symposium


Abstract: Although the majority of high reliability devices are exempt from RoHS legislation, many manufacturers are being forced to investigate lead-free products and processes. As component suppliers change their products over to lead-free finishes, many of them discontinue the availability of tinlead plating totally. The unavailability of tin-lead component finishes forces the exempt manufacturer to invest either in identifying substitute sources or in qualifying parts with alternative finishes.

To further exacerbate the issue, more assembly processes transition to lead-free every day. Current projections indicate that by 2010, 90% of all circuits assembled will be lead-free. Although tin lead-processes will continue to exist, their associated costs can be expected to rise as tinlead processing evolves into a niche market.

There are plenty of case studies on how to transition to leadfree; the real question for exempt manufacturers is when to transition. If an assembler transitions in the near term, they will face more of the lead-free assembly issues that are not yet resolved. Conversely, if the assembler delays transition, they will continue to face increased pressures of component changes. This paper reviews the process considerations exempt manufacturers should think about when determining the future of their assembly processes.

Key words: lead-free, high reliability, mixed metals, copper erosion, blow holes



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