Mechanical property of the epoxy-contained Sn–58Bi solder with OSP surface finish

Abstract

In the electronic packaging technology, lead-free solders have been widely used to replace lead-based solders because of the toxicity of lead. Among the investigated lead-free solders, the Sn–58Bi solder has been considered as a highly promising candidate because of its low-melting temperature, high tensile strength and good creep resistance. However, the Sn–58Bi solder has poor ductility and shock absorbance. To enhance the mechanical properties of the Sn–58Bi solder, epoxy resin is mixed with the Sn–58Bi solder. The advantages of the Sn–58Bi solder with epoxy are good reliability and no need of a cleaning process. This study elucidated not only the mechanical properties of the Sn–58Bi epoxy solder but also the effects of the epoxy during the reflow process by conducting a shear test and a board-level drop test. The shear strength of the Sn–58Bi epoxy solder was about 2 times higher than that of the Sn–58Bi solder. In result of the drop test, the Sn–58Bi solder specimen failed under the 10th drop. However, the number of drops of the Sn–58Bi epoxy solder was over 100 drops without failure.