The microstructure evolution and activation energy study of Cu₆Sn₅ and Cu₃Sn intermetallic compound layer of Sn-10Cu/Cu solder joint

The electronic packaging industry is gradually moving away from lead solder to lead-free solder, which is more environmentally friendly. However, there is still work to be done to ensure that lead-free solder meets the demands and requirements of the latest technology. The present study demonstrates the analysis of the microstructure formation of Cu₆Sn₅ and Cu₃Sn intermetallic compound layers in Sn-10Cu/Cu solder joints. Therefore, the key objective of this research is to determine the growth rate and activation energy of the Cu₆Sn₅ and Cu₃Sn intermetallic compound layer of the Sn-10Cu/Cu solder joint. The investigation on the bulk solder microstructure which consists of Cu₆Sn₅ and Cu₃Sn intermetallic compound layer was carried out using Optical Microscope (OM), Scanning Electron Microscope (SEM) with EDX and ImageJ software. The IMC layer undergoes rapid growth with increasing aging temperature and duration and the two main IMC layers (Cu₆Sn₅ and Cu₃Sn) grew thicker. The growth kinetic solder joints for Sn-10Cu and Sn-0.7Cu are 22.44 kJ/mol and 31.20 kJ/mol, respectively. Hence, the findings from this study may offer useful information for the development of high-reliability solder joints in future applications.