Assessment of Solder-Dipping as a Tin Whisker Mitigation Strategy

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 are subjected to the solder-dip process. For this paper, the solders included eutectic tin-lead and tin-silver-copper. In addition, tin-bismuth (Sn-Bi) finished alloy 42 lead-frame parts are also examined to assess the effectiveness of the Sn-Bi finish in mitigating tin whisker growth. Parts under study are subjected to temperature cycling conditions to promote whisker formation. It is observed that whiskers are 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.