Microstructural change and hardness of lead free solder alloys

Abstract

Two types of Pb free solder, Sn-Ag eutectic alloy and Sn-Zn eutectic alloy, as potential replacements for Sn-Pb eutectic solder and Sn-Pb eutectic alloy were found to age-soften during storage at room temperature (25 C, 298 K, 77 F) and high temperature (100 C, 373 K 212 F). The hardness of another type of Pb free solder, Sn-Bi eutectic alloy, did not change during storage at room and high temperature. However, the microstructure of Sn-Bi eutectic alloy coarsened unusually during storage at room and high temperature.