CuAgSnIn composite joints with rapid bonding and high shear strength for power electronic packaging

Solid-liquid interdiffusion bonding (SLID) technology offers the advantages of low-temperature preparation and high-temperature operation, making it suitable for the operation requirements of wide-bandgap semiconductor devices under high junction temperature and high-power conditions. Nevertheless, existing technology still suffers from drawbacks such as the excessively long bonding time (>4 h) and the formation of holes and cracks during phase transformations, limiting their application.In this work, a high-strength full intermetallic compound (IMC) joint was rapidly (30 min) fabricated using the Cu20Ag20Sn20In composite paste as the interlayer material by SLID process. The microstructure evolution, interfacial reaction, and shear behavior of the joints under different bonding temperatures were investigated. The results demonstrate that the composite paste can achieve a rapid bonding with the Cu substrate at 200°C within just 30 min. As the temperature increases to 300°C, the microstructure is entirely composed of a network structure of Cu₆(Sn, In)₅, Cu₃(Sn, In), and Ag₃(Sn, In) IMCs with high bonding quality. The shear strength of the joints increases to over 80 MPa. In addition, the thermal aging reliability was preliminarily evaluated by shear strength. After aging at 300°C for 168h, the shear strength of the joints remains above 60 MPa. This SLID strategy with multi-principal low-melting-point and high-melting-point components is an effective method to shorten the bonding time and improve the bonding quality for full IMC joints in power electronics packaging.