Novel Cu@Ag Micro/Nanoparticle Hybrid Paste and Its Rapid Sintering Technique via Electromagnetic Induction for High-Power Electronics

Abstract

Due to the harsh working environments up to 600 °C, the exploration of high-temperature interconnection materials is significantly important for high-power devices. In this study, a hybrid paste including Cu@Ag core–shell microparticles (MPs) and Ag nanoparticles (NPs) was designed to achieve Cu–Cu bonding. The Cu@Ag MPs exhibited excellent oxidation stability in an air atmosphere with the Ag layer coating on the Cu core. Ag NPs fill the pores among the Cu@Ag MPs and reduce the sintering temperature of the hybrid paste. The Cu–hybrid paste–Cu joints were formed via electromagnetic induction heating within approximately 15 s. When sintered at 26 kW, the shear strength of the joint reached 48 MPa, the porosity decreased to 0.73%, and the resistivity was down to 13.25 μΩ·cm. Furthermore, a possible interconnection mechanism at the contact interface between the Cu substrate and the sintered hybrid paste was proposed, which is related to the melting point of metal particles and the effect of magnetic eddy currents. This fast bonding technology inspires a new approach to interconnection for high-power devices under high operation temperatures.