A constitutive model for a high lead solder

High lead solders have been widely used in chip scale packaging. This paper presents a comprehensive study of the various properties, such as Young's moduli, creep, plasticity, cyclic hardening and softening, fatigue, of a typical high lead solder, 96.5Pb-3.5Sn. Based on these studies, a unified creep and plasticity approach, incorporating damage, is adopted to construct a three-dimensional constitutive model for this solder. The model is then used to simulate cyclic hardening and softening behavior, isothermal and nonisothermal loading, and damage during the fatigue process. Experimental results from uniaxial tension tests are used to verify the model and good agreement has been achieved.