Effects of Ce and Zn additions on the microstructure and mechanical properties of Sn–3Ag–0.5Cu solder joints

Abstract: It has been reported that the rapid growth of tin whiskers occurring on the surface of rare earth containing solders can be prevented by the addition of 0.5wt.% Zn into a Sn–3Ag–0.5Cu–0.5Ce alloy. The present study shows that the tensile strength of Sn–3Ag–0.5Cu–0.5Ce alloy alloyed with Zn increases significantly in comparison to the Zn-free Sn–3Ag–0.5Cu and Sn–3Ag–0.5Cu–0.5Ce solder. Moreover, the growth of intermetallic compounds at the solder/pad interfaces during the thermal aging at 100°C and 150°C was inhibited by the Zn addition. Nevertheless, the excess of Zn addition to 0.5wt.% causes poor junction in the Sn–3Ag–0.5Cu–0.5Ce packages. An optimized addition amount of Zn in Sn–3Ag–0.5Cu–0.5Ce solders is 0.2wt.% for both inhibiting the growth of tin whiskers and strengthening the solder joints, although its ductility is still lower than that of the original Sn–3Ag–0.5Cu. [Copyright &y& Elsevier]