Effect of Thermomechanical Treatment with Single Compression on Microstructural and Micromechanical Properties of Sn-0.7Cu Solder Alloy

Lead-free solder alloys have been widely used as interconnection materials for electronic devices that provide electrical connections for functionality and mechanical support for structural integrity. Thermomechanical treatment is a metallurgical process that involves a combination of thermal treatment and mechanical loading. This study aimed to investigate the effect of thermomechanical treatment with single compression on the microstructural changes and micromechanical properties of the Sn-0.7Cu solder alloy. A bar-shaped Sn-0.7Cu solder alloy was cut up into eight samples cube-shaped with dimensions of 6 mm (l) x 6 mm (w) x 10 mm (h). The first four samples were subjected to heat treatment for 20 min at 30 degrees C, 60 degrees C, 90 degrees C, and 120 degrees C, followed by single compression of 20% and water medium. The next four samples were subjected to heat treatment only, followed by quenching in a water medium used as control samples. Microstructural observation shows that small and uniform grains of Sn-0.7Cu solder alloy was formed from thermomechanical treatment with single compression at 120 degrees C due to grain recrystallization. The hardness result for Sn-0.7Cu solder alloy after thermomechanical treatment with single compression at 120 degrees C has shown tiny changes of 19% as compared to heat-treated samples with 64%. Reduced modulus results also showed the same trend whereby the lesser changes for the thermomechanical treatment sample were about 52% while the heat-treated sample was about 69%. The findings of this study indicate that the temperature in thermomechanical treatment with single compression has been able to alter the microstructure and give stability to the micromechanical properties of Sn-0.7Cu as opposed to heat treatment.