High-temperature shear strength and hardness of cast lead-free solders

Abstract

This paper compares the shear strength and hardness of the tin-based cast lead-free Sn-2Bi, Sn-5Sb, and Sn-9Zn binary solder alloys. This was achieved respectively by the shear punch testing (SPT) and Vickers hardness measurement in the temperature range 298-370 K. The results showed that the shear yield stress (SYS), ultimate shear strength (USS), and hardness (Hv) of all three alloys decrease with increasing test temperature. Among all tested materials, Sn-2Bi showed the highest strength and hardness over the whole testing temperature range. This is ascribed to the strong solid solution effect of Bi in the Sn matrix, which is superior to the weak solution hardening and particle strengthening effects of Sb in Sn-5Sb, and particle hardening of Zn in Sn-9Zn.