Effect of adding Ge on rapid whisker growth of Sn-3Ag-0.5Cu-0.5Ce alloy

Although solders doped with rare earth elements have been reported to show many beneficial effects, tin whisker growth has been observed to grow at an extremely high rate on the surface of such novel solder alloys. This study shows that adding 0.5 wt.% Ge into a Sn-3Ag-0.5Cu-0.5Ce alloy effectively decreased whisker growth. This inhibition effect is attributed to alleviation of oxidation in the CeSn3 intermetallic phase in this alloy as a result of Ge-alloying. Compressive stress in this case is insufficient to extrude tin atoms out of the solder to form whiskers.