Mechanism of tin whisker morphology

The morphological mechanisms of tin whisker growth on the surface of oxidized CeSn3 and ErSn3 precipitates were investigated during the aging.The results indicate that most tin whiskers have constant cross section and regular shape.However,few irregular tin whiskers with special morphologies are also observed,including the spiral whiskers,whiskers with a non-constant cross section,branch-type whiskers and joining-type whiskers.Since the produced lattice expansion of the rare earth precipitates oxidization provides driving force for the tin whisker growth,and the oxidization is extremely uneven.Therefore,the changes of stress around the tin whisker root will primary cause that results in the growth of irregular tin whiskers.