Study of microstructure and mechanical properties of Cu/In-45Cu/SiC joints connected by ultrasonic-assisted TLP

Abstract

With the application of the third-generation semiconductor SiC in high-power, high-current-density devices, the service temperature of electronic devices is getting higher and higher, and the traditional soldering materials and technologies are facing many technical problems, making it difficult to achieve the goal of “low-temperature connection and high-temperature service.” In this paper, a new type of In45Cu composite solder paste was developed to address this problem, and all-Cu2In IMC can be obtained at a service temperature of 600 °C by using ultrasonic-assisted TLP at 260 °C. In this paper, the effects of ultrasonic action time on the microstructure evolution, shear strength, and growth mechanism of intermetallic compounds (IMCs) of the joints were investigated. The results showed that the cavitation effect and acoustic flow effect of ultrasound accelerated the reaction between liquid In and Cu particles, and when the ultrasound action time was 30 s, all In and Cu particles in the joint were transformed into Cu2In, and the shear strength of the joint was 19.69 MPa, at which time the joint was dense due to the expansion of the volume of Cu2In, which eliminated the voids caused by the volume shrinkage of Cu11In9, making it possible for the electronic device to serve for a long time at high temperature.