High temperature deformation characteristics of tin-based solder alloys: Application to electronic packaging

Deformation characteristics of pure tin metal, Sn-3.5Ag and Sn-5Sb have bee n investigated at various temperatures between ambient and 473 K from const ant load creep tests in order to understand the deformation behaviors of th ese materials. Automated ball indentation (ABI) studies were also carried o ut as a non-destructive testing technique to characterize the mechanical pr operties of these alloys. Power-law relationships between strain rate and s tress were observed under both loading conditions. The stress exponents and the activation energies were determined and the values correspond to creep deformation by dislocation climb controlled by lattice diffusion in pure t in and Sn-3.5Ag, and viscous glide controlled by pipe diffusion in Sn-5Sb a lloy. Excellent agreement was found between creep and ABI results of Sn-5Sb alloy but such a correlation was not evident in the case of pure tin and S n-3.5Ag alloy. Agreement between creep and ABI data indicates that ABI can be successfully applied for studying the deformation behavior of Sn-5Sb sol der joints in actual components in the electronic packaging industry. These results on bulk materials are compared with the initial results on the cre ep behavior of solder bump arrays.