Viscoplastic Deformation of 40 Pb/60Sn Solder Alloys—Experiments and Constitutive Modeling

This study first proposes a simple constitutive model for viscoplasticity, which includes the elastic, plastic, and creep strains independently. The plastic strain is evaluated by the flow rule employing back stresses evolved with a Ziegler type of hardening rule. The creep strain is evaluated by the modified Norton’s law. The applicability of this constitutive model is evaluated with pure tensile tests, creep tests and cyclic tension-compression loading tests, to demonstrate the progress of viscoplastic deformation of 40Pb/60Sn solder alloys. The tests were conducted over both several temperature ranges and strain rates. As a result, it was found that the material constants used in the constitutive model could be determined by simple tests such as pure tensile and cyclic tension-compression loading tests. The simulation by the constitutive model explains accurately the viscoplastic deformation of the 40Pb/60Sn solder alloys.