Oxidation-Free Bonding of Cu Sintering in the Air on Cold-Rolled Bare Cu Substrate

Inhalt:
This study was carried out to realize Cu sintering in air atmosphere and investigate the driving force of oxidation-free Cu sintering. Cu sintered joints were successfully achieved at 250 °C in the air with a uniform pressure bonding 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 54.53 MPa with sintering for 30 min. In particular, it is interesting to note that no oxidation layers of Cu sintered joints were 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 joint structure involved in the Cu substrate rolling percentage and the mech-anism of bonding strength, considering the relationship between microstructures and mechanical behaviors.