First-Principles Study on IMC Formation and Interface Failure of Electronic Packaging Solder Joints

Abstract At present, Sn-3.0Ag-0.5Cu (SAC305) solder is one of the commonly used lead-free solders, and copper-clad laminate PCB substrate. SAC copper substrate mainly generate two intermetallic compounds (IMCs) Cu6Sn5 Cu3Sn during soldering process. Based on first principles, this paper analyzes formation difficulty kinds IMCs generated in soldering, failure mechanism Sn/IMC IMC/Cu interfaces. Firstly, based density functional theory (DFT), “CASTEP” module Material Studio (MS) to analyze from point states, population analysis, energy. The results show that easier generate, which also explains reason for generation initial stage soldering. Then, Sn / IMC Cu interfaces were established MS, why joint occurred at interface was explained by energy analysis.