Whisker growth on annealed and recrystallized tin platings

The aim of this research is to examine the effects of annealing and recrystallization of electroplated tin layers on mitigating the growth of tin whiskers. Tin plating electroplated on copper substrate has been tested. Three different groups of samples have been investigated: reference, annealed and recrystallized. Three types of ageing were being used to accelerate the whisker appearance: two life-like circumstances with a constant elevated temperature in low humidity and a temperature cycling test. The whisker growth was observed by using scanning electron microscopy and was evaluated by the average and maximum whisker length and the average whisker density. It is shown that at different ageing temperatures whisker appearance and growth are decreasing in aspect of the applied pre-treatments. The effects of the pre-treatments were explained by changes of the grain structure in the tin layer which were observed with focused ion beam.

► Whisker mitigation of annealing and recrystallization was examined on tin platings.
► The treatment methods delay the time of the first whisker appearance.
► The different treatment methods resulted in different tin grain structures.
► Large amount of voids were observed under the developed hillocks and nodules.