| Abstract Scope |
Advanced electronic packaging requires solder alloys with reduced processing temperatures and stable interfacial reactions. In this study, Bi and In were added to the Sn-Ag-Cu system to develop Sn-Ag-Cu-In-Bi medium-temperature lead-free solders. The effects of Bi and In on melting behavior, phase formation, thermal aging stability, and Cu/solder interfacial reactions were investigated. Differential scanning calorimetry, X-ray diffraction, electron probe microanalysis, and cross-sectional microscopy were used for characterization. The results showed that In and Bi effectively reduced the melting temperature of SAC-based solders and slower the growth of intermetallic compound at the interface. After reflow, the interfacial layer was mainly Cu6(Sn,In)5, while limited Cu3(Sn,In) formation was observed after aging. Kinetic analysis showed that Bi-In addition influenced IMC growth behavior, suggesting the importance of composition control for interfacial stability. |