Soldering process of the SiC-Cu joint and its microstructure and properties

Research on the application requirements of low-temperature packaging based on high-power SiC devices, and develop a low-temperature connection process between SiC ceramics and heat dissipation Cu plates. The SiC-Cu brazing joint was successfully achieved by surface metallization of silicon carbide through magnetron sputtering technology and low-temperature vacuum soldering with Sn-based fillers. The influence of the thickness of metallized Cu layer on SiC and the composition of the Sn-based fillers on microstructure and mechanical properties of the SiC-Cu joint was analyzed and realized. It is proposed that the shear strength of SiC-Cu joints depends on the degree of metallurgical reaction close to the boundary between SiC and Sn-based fillers, which is influenced by the composition of Sn-based filler and the thickness of the metallized Cu layer on the surface of SiC. In general, the SnCu alloy was recommended to serve as the filler due to its nice metallurgical reaction wtih the Cu film on SiC. In this case, the intermetallic compound (IMC) near SiC in the SiC-Cu joint is mainly Cu₆Sn₅ and its quantity increases with the increasing thickness of the Cu film, leading to the improvement of shear strength of the joint. As a result, the SiC-Cu joint soldered by SnCu filler has a peak shear strength of about 14 MPa when the thickness of Cu film on surface of SiC is about 2000 nm.