Rapid whisker growth on the surface of Sn–3Ag–0.5Cu–1.0Ce solder joints

In spite of the many beneficial effects obtained from the addition of rare earth elements to solder alloys, rapid growth of tin-whiskers has been found in Sn–3Ag–0.5Cu–1.0Ce solder joints. The morphology of the whiskers changes from fiber-shaped to hillock-shaped when the storage temperature increases from 25 to 150 °C. The driving force for the whisker growth is the compressive stress resulting from the volume expansion of the oxidized CeSn3 phase, which is constrained by the surrounding solder matrix.