Modified Anand constitutive model for lead-free solder Sn-3.5Ag

An improved Anand constitutive model is proposed to describe the inelastic deformation of lead free solder Sn-3.5Ag used in solder joints of microelectronic packaging. The new model accurately predicted the overall trend of steady-state stress-strain behavior of the solder for the temperature range from 233 K to 398 K and the strain rate range from 0.005 s^-1 to 0.1 s^-1·h₀, a constant in the original Anand model, was set to a function of temperature and strain rate in the proposed model. Comparison of the experimental results and simulated results verified that the improved Anand model with modifying h₀ to a function reasonably simulated the inelastic stress-strain relationships.