Rate-dependent indentation behavior of solder alloys

Finite element (FE) simulations of visco-plastic indentation in Sn-37Pb eutectic solder alloy are performed to investigate the influence of loading rate on its creep characteristic. The resulting indentation load-displacement curves are rate-dependent and have varying creep penetration depths during the same hold time. Creep indentation hardness H, defined from the concept of “work of indentation”, varies with volume strain occurring during the creep hold time, which is a measure of creep strain rate ˙εcr. Thus, creep stress sensitivity can be determined from the H versus ˙εcr curve. This analysis can be verified by the good agreement between the derived value and the predefined value, and then be used to analyze the Berkovich indentation load-displacement curves of Sn-3.5Ag-0.75Cu lead-free solder. Such indentation tests and physical analysis provide a cheaper and more convenient method to determine the mechanical properties of the upcoming lead-free solder alloys. C 2005 Springer Science + Business Media, Inc