Recent Advances in Mitigation of Whiskers from Electroplated Tin

Abstract

Tin whiskers pose an electrical reliability risk in the form of potential short circuits. This problem was solved in the past by adding a few percent of Pb during Sn electroplating, but with the ban on Pb in Europe and elsewhere, it has resurfaced. While various mitigation strategies have been formulated based on known whisker growth mechanisms, the electronic industry is still awaiting a satisfactory solution to the whisker growth problem in Pb-free electronics. Recent advances in the understanding and mitigation of whiskers are reviewed herein. The effects of various alloying elements/dopants are discussed in terms of the mechanisms that impact whisker growth kinetics and mitigation. Most recently, indium addition to Sn has been found to eliminate whiskers with even better mitigation performance than Pb addition. The mechanisms are discussed, and the important role of indium on the surface oxide and subsurface enrichment is highlighted.