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

In requirement of the low-temperature packaging applications for high-power SiC devices, a low-temperature bonding process for SiC ceramics and heat-dissipating Cu plate is put forward in this research. The SiC-Cu 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. 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.