Shunong Zhang, Rui Kang, and Michael G. Pecht, Fellow, IEEE
This paper discusses the corrosion process of immersion silver (ImAg) board finish on printed circuit boards subjected to elemental sulfur environments in the presence of high-sulfur content clay and moisture. The tests induced various types of metal migration processes and corrosion products.Migration phenomena ranged from short dendrites of Ag2S, Cu2S, and CuS, which grew fromImAg surface edges without solder masks, to long dendrites of Cu2S growing from ImAg surface edges with solder masks that had copper traces beneath them.
Index Terms—Clay test, elemental sulfur environment, immersion silver (ImAg), printed circuit boards (PCBs).
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