In-air Cu Sintering with Partial Encapsulation System for SiC Power Module

This study was carried out to realize Cu sintering in the air atmosphere and investigate the driving force of oxidation-free Cu sintering. Cu sintered joints were successfully achieved at the temperature of 250 °C in the air with a uniform pressure below 10 MPa. A mechanism was applied in which oxygen was instantaneously blocked from the entire volume of the die-attach specimen during the sintering process. Consequently, we achieved bonding strengths exceeding approximately 36 MPa with a Cu particles size of 0.3 μm. In particular, it is interesting to note that no oxidation layer was observed at sintered bonding at 250 °C in the air atmosphere. The bonding strength was fundamentally attributed to the interfacial connected ratio between the Cu substrate and Cu sintered layer. This study systematically investigated the Cu-sintered joints structure involved in the size of Cu particles and the mechanism of bonding strength, considering the relationship between microstructures and mechanical behavior.