Effect of Microstructure Size on Deformation Kinetics and Thermo-Mechanical Fatigue of 63Sn37Pb Solder Joints

Abstract

An increased cooling rate following reflow produced a decrease in the microstructure size including the size of the colonies, the Pb-rich dendrites and the eutectic phases. The decrease in microstructure size gave an increased creep rate at room temperature and a decrease in the creep stress exponent. Also, thermo-mechanical fatigue crack growth rate decreased and fatigue life increased with the decrease in microstructure size. These effects of the increased cooling rate were attributed to an increase in boundary sliding which could occur from the increase in boundary area with decrease in microstructure size.