Effects of temperature and strain rate on tensile properties of (Ag,Cu)-Sn intermetallic compounds: A molecular dynamics study

With the advent of environment friendly microelectronic packaging technologies, the demand of lead-free solders alloy has escalated. Leadfree solder material is an alloy of Tin (Sn), Silver (Ag) and Copper (Cu) and is widely known as SAC solder. Intermetallic compounds (IMC) like Ag3Sn, Cu3Sn and Cu6Sn5 are proven to adversely affect the mechanical properties of lead-free solder joints. This study presents the effects of temperature and strain rate on mechanical performances of these IMCs found in SAC solders. In addition, weakest and most sensitive IMC among these is detected. Modified embedded atom method potential parameters are used in LAMMPS to simulate the stress-strain behavior with deformation evolution of intermetallic compounds in different temperature and strain rates. The simulation was performed at 298 K–498 K with 50 K regular increment and at the strain rates of 108 s−1, 109 s−1, and 1010 s−1. Insight from this study suggest that the tensile properties of these IMCs increased with the increased in strain rates and decrease in temperature. Furthermore, the effect of temperature on tensile strength is observed to be higher at low strain rate whereas strain rate influence is lower at low temperatures. Among all the intermetallic, Ag3Sn exhibits lowest tensile properties with lowest stability, conversely Cu3Sn exhibits highest tensile properties with highest stability.