SMTA International Conference Proceedings


THE INFLUENCE OF THE PWB FABRICATION ELECTRODEPOSITION PROCESS ON COPPER EROSION DURING WAVE SOLDERING

Authors: Chrys Shea, Jim Kenny, Jean Rasmussen, Shiang Teng, Girish Wable, Quyen Chu, Keith Sweatman, and Kazuhiro Nogita, Ph.D.
Company: Cookson Electronics, Jabil, San Jose State University, Nihon Superior, and University of Queensland
Date Published: 10/11/2007   Conference: SMTA International


Abstract: Lead-free solder alloys, particularly those with higher silver and lower copper contents, have been shown to react with the copper on circuit boards to dissolve the copper much more quickly than tin-lead solders. Rapid dissolution of copper into tin-rich alloys can create hidden defects and reliability issues. As copper is washed off the PWB, the exposed traces, annular rings, and barrel knees can become thinner or even nonexistent.

A series of studies have been developed to gauge the effect of copper erosion on PWBs when exposed to various combinations of time, temperature and alloy in both standard and selective soldering processes. The study was broken in to phases, the first of which aimed to isolate the influence of the copper’s manufacturing process on its likelihood to erode during subsequent soldering processes. The results of phase 1, using SAC305 solder alloy, are presented.

Key words: Lead-free, wave soldering, copper erosion, copper dissolution



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