Work

Interface and microstructural reliability analysis of cu hybrid sintered joints on Ni/Au-metallized SiC under high-temperature oil and air aging

Year: 2026

Type: article

Abstract: Copper (Cu) sintering has attracted significant attention as a cost-effective alternative to Ag-based die-attach materials for high-temperature power electronics. Oxidation remains one of the most critical issues for Cu sintering, particularly during high-temperature aging. In this study, the interfacial and microstructural reliability of Cu hybrid particles sintered joints formed between Ni/Au-metallized SiC chips and a Cu sintering paste was systematically investigated under isothermal aging in an insulating oil environment at 250 °C for up to 1000 h. In addition, identical joint samples were subjected to aging in air for comparison. While specimens aged in air suffered from oxidation-induced degradation and interfacial delamination, specimens aged in oil exhibited a continuous increase in shear strength, from an initial value of 33.8 MPa to 53.0 MPa after 1000 h. Correspondingly, the fracture mode evolved from brittle granular failure to ductile cohesive fracture within the Cu matrix. Cu-Au interdiffusion occurred during sintering and intensified with aging time. In contrast, the Ni layer exhibited excellent stability during aging, with no observable diffusion into the Au layer, thus preserving the integrity of the bonded interface. These results indicate that without oxygen, the sintered Cu joints with Ni/Au metallized SiC have a good high-temperature reliability, supporting sinter Cu paste applicability to Ni/Au metallized SiC power modules.

Source: Materials Characterization

DOI: 10.1016/j.matchar.2026.116924