TEMPERATURE-INDUCED THICKNESS REDUCTION OF MICROMECHANICAL PROPERTIES OF Sn-0.7Cu SOLDER ALLOY

Abstract

Solders are used in electronic packaging for metallurgical interconnections. Thermomechanical methods are used to modify the properties of a material. Cubic Sn-0.7Cu solder alloy was subjected to heat treatment at 30–150 °C for 20 min, followed by 80 % compression. The control samples used in this study were only subjected to heat treatment. This study used the nanoindentation approach to investigate the reductions in the modulus and hardness of the lead-free Sn-0.7Cu solder alloy after thermomechanical treatment. Samples with 80 % compression showed slight changes in the reduced modulus (approximately 24 %) and hardness (approximately 14 %) after thermomechanical treatment. In contrast, the solder alloy that underwent heat treatment alone (the control sample) showed shifts in the hardness and reduced modulus of approximately 54 % and 66 %, respectively. The production of new recrystallized grains resulted in smaller changes in the micromechanical properties. These findings demonstrated that thermomechanical treatment can both modify and stabilize the properties of the Sn-0.7Cu solder alloy, such as micromechanical properties.