Sony Mathew, Weiqiang Wang, Michael Osterman and Michael Pecht
Center for Advanced Life Cycle Engineering (CALCE)
University of Maryland, College Park, MD, 20742
Tin whiskers have been brought back into the spotlight due to the transition of the electronics industry to lead-free solders. Many different tin whisker failure mitigation strategies are being evaluated by researchers. This paper investigates the technique of solder dipping as a tin whisker mitigation strategy for tin-based lead-free finished surfaces used in electronic products. Tin finished Alloy 42 lead-frame parts were subjected to solder dip process. For this study, solders included eutectic tin-lead and tin-silver-copper. In addition, tin-bismuth finished alloy 42 lead-frame parts were also examined to assess the effectiveness of the tin-bismuth finish in mitigating tin whisker growth. Parts under study were subjected to temperature cycling conditions to promote whisker formation. It was observed that whiskers were formed on all treatment surfaces, with the longest whiskers occurring on the pure tin finished parts. The solder dipped parts showed better mitigation of tin whiskers than the pure tin finished parts.
Keywords: Solder dipping, tin whiskers, Alloy 42 leads, tin plating, SAC, SnPb, SnBi, temperature cycling.
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