Effect of Ni content on the creep properties of Cu/Sn–0.3Ag–0.7Cu/Cu solder micro-joints

The tensile creep properties of line-type Cu/Sn–0.3Ag–0.7Cu(SAC0307)–xNi (x = 0, 0.02, 0.05 and 0.10 wt%)/Cu solder micro-joints were comparatively investigated via dynamic mechanical analysis. The effect of Ni content on the creep behaviour of the solder micro-joints was analysed and discussed. The creep behaviour of the joints at various temperatures and applied stresses was described by a power law. The results showed that the creep lifetime, creep activation energy and creep stress exponent of the Ni-containing solder micro-joints were greater than those of the Ni-free joint. Hence, adding Ni to the SAC0307 solder can enhance the creep resistance of the solder joints. The creep activation energy and the creep stress exponent of the solder micro-joints at 353–398 K and under a tensile stress of 8–15 MPa were 82.44–93.36 kJ/mol and 4.35–4.75, respectively. As the Ni content increased, the creep activation energy and the creep stress exponent first increased and then decreased. The Cu/SAC0307–0.05Ni/Cu solder micro-joint exhibited the strongest creep resistance among the tested joints. The creep deformation mechanisms of all solder micro-joints were mainly controlled by dislocation climbing, and the main creep failure mode was mixed brittle/ductile fracture.