The melting point of tin-zinc based lead-free solders is low. Therefore it might be adequate to substitute tin-zinc solders for tin-lead solders. However, the mechanical properties of tin-zinc solders have not been fully investigated. The tensile strength of tin-zinc eutectic solder is higher and the elongation is not smaller than tin-lead eutectic solder. The fatigue life of tin-zinc eutectic solder is longer than tin-lead eutectic solder. Microstructure of tin-zinc eutectic solder is unique because micro-needles and large linear phases of zinc disperse at random on matrix of tin phase. We investigated the microstructures both before and after fatigue tests.
