Effects of Cooling Rate on the Stress-Strain Behavior of SAC305 Solder: An Atomistic Study

Abstract

Abstract SAC305 (96.5Sn-3.0Ag-0.5Cu) is a lead-free solder alloy that has gained popularity as a replacement for traditional lead-based solders due to its lower melting point, environmental benefits, and compatibility with common electronic components. In this study, Molecular Dynamics simulations are used to investigate the effects of cooling rate on the mechanical properties and stress-strain behavior of SAC305 at the nanoscale. The simulations utilize an atomistic model of the material, where a beta-tin (β-Sn) matrix is modified with Ag and Cu atoms. Four different cooling rates such as 2.5 K/ps, 10 K/ps, 50 K/ps, and 100 K/ps are used to examine the effects on the micro structure and mechanical properties of the solder material. The results of the simulations are analyzed in terms of ultimate tensile strength, Young’s modulus, modulus of resilience, modulus of toughness, and coefficient of thermal expansion. The stress-strain behavior is found to be more strongly affected at slower cooling rates (2.5 K/ps and 10 K/ps), while at higher cooling rates (50 K/ps and 100 K/ps) have less of an impact. An inverse relationship is observed between cooling rate and the ultimate tensile strength of the material, as well as its Young’s modulus and modulus of resilience. Furthermore, as the cooling rate increases, the modulus of toughness of the material has also been observed to increase. The coefficient of thermal expansion has been observed to decline as the rate of cooling increases.