Mechanical Characterization and Viscoplastic-Damage Constitutive Model of SnAgCu Solder

Due to the toxicity of Pb present in Sn-Pb solders used in many electronic products, alternative solders need to be considered. Recently, there has foucused its interedt on Sn-Ag-Cu(SAC) alloy because of its comparative low melting temperature, the competitive price, and apparently good mechanical properties. The time- and temperature-dependent deformation behavior of Sn4.0Ag0.5Cu solder alloy was determined over strain rates ranging from 10-5s^-1 to 10-2s^-1 and temperatures ranging from 25degC to 150degC. A viscoplastic-damage model incorrporating the effect of microstructural was developed for capturing the complex hierarchy of damage mechanisms, coupled with viscoplastic and stress state effects. The temperature and rate dependent flow properties of the matrix material have been obtained by inverse procedure. The model was also implemented into finite element program ABAQUS through its user defined material subroutine. The model is validated by comparing the predictions to the experimental data involving temperature, loading rate. The predictions have shown the ability of the modified viscoplastic-damage model coupled with microstructural damage to correctly describe the experimental observations: nonlinearity, strain rate sensitivity and damage evolution.