Shear punch creep behavior of cast lead-free solders

Creep behavior of the tin-based lead-free Sn-2Bi, Sn-5Sb, and Sn-9Zn, binary alloys was studied by the newly-developed shear punch creep testing (SPCT) technique in the temperature range 298-375 K. Assuming a power law relationship between the creep rate and shear stress, stress exponents of 8.4-11.4, 8.5-11.5, and 6.4-9.3 and average activation energies of 63.4, 61.4 and 40.2 kJ mol−1 were obtained for Sn-2Bi, Sn-5Sb, and Sn-9Zn, respectively. These creep parameters are in good agreement with those determined by tensile, impression, and indentation creep testing of the same materials reported in the literature. Among all tested materials, as indicated by their minimum creep rates, the solution hardened Sn-2Bi showed the highest creep resistance followed by Sn-5Sb with weak solution and particle hardening effects, and Sn-9Zn that benefits merely from particle hardening. Different creep behaviors of the materials were discussed in terms of their microstructural features.