Bismuth-Antimony as an Alternative for High Temperature Lead Free Solder

Abstract

The development works on high temperature lead free solder are mostly discussed nowadays. To replace the current high temperature lead free solders, further research need to be done. A great deal of effort has been put into the development of lead free solder alloys. Bi (Bismuth) and Sb (Antimony) solder system proved as one of the promising candidates for electronic assembly. Melting temperature of three Bi-Sb solder alloys studied in this research enhanced their potential as the alternative solder candidates for high temperature lead free solder. At interface, Cu3Sb IMC layer was formed for 95Bi-5Sb solder alloy. Spallation of Cu3Sb IMC layer took placed with the results of Cu3Sb IMC also found in the solder bulk. Analysis of 97.5Bi-2.5Sb solder alloy classified as no metallurgical reaction at the interface and only the mechanical joining existed at the interface. The dissolution of Cu from subtrate affected the formation of Cu rich phase and the unstable Bi-Cu rich phase phenomena act as the isothermal product found in solder bulk. Mechanical grain boundary grooving observed in 98.5Bi-1.5Sb solder alloys at interface. Different compositions of Bi-Sb solder alloys resulted in different types of microstructures at interface and in solder bulk after reflow.