Investigation on high-temperature long-term aging of Cu-Sn intermetallic joints for power device packaging

This paper conducted high-temperature aging to investigate the thermal reliability of Cu-Sn full intermetallic compound joints. Microstructural evolution, interfacial reactions, and mechanical property of aged joints were analyzed. Results demonstrated that porosity and the thicknesses of interfacial Cu3Sn were increased with aging time and temperature. For joints aged at 250 °C, after 360 h, joints consisted of Cu6Sn5 and Cu3Sn. For joints aged at 350 °C, after 240 h, full Cu3Sn joints were obtained. The shear strength was initially enhanced and subsequently reduced with aging duration. After 360 h, aged joints had excellent mechanical reliability (17.61 MPa at 250 °C and 15.47 MPa at 350 °C). The kinetics of the Cu3Sn growth and Cu substrate dissolution was investigated. The relationship between the thicknesses of interfacial Cu3Sn and the square root of aging time obeyed the linear law. The activation energy for Cu3Sn growth was 87.421 kJ/mol.