Bonding Parameter-Dependent Microstructural and Mechanical Capabilities of Ag Porous Sheet Bonding

Our group successfully achieved sintered bonding at 145 °C, which is the lowest temperature known to be "theoretically" possible for the Ag sintering, and by uniformly pressing with 10 MPa for 5 and 10 min at 145 and 175 °C, respectively. Consequently, we achieved bonding strengths exceeding approximately 20 MPa with a bonding time of only 5 min at 145 °C. In particular, it is interesting to note that in the pressure sintering bonding process at 145 °C, bonding times of 5 and 10 min had no significant difference in strength. Even with a bonding temperature of 175 °C, the difference in average bonding strength between bonding times of 5 min (i.e., 37.6 MPa) and 10 min (i.e., 43.0 MPa) was only 5 MPa. The bonding strength was fundamentally attributed to the interfacial connection ratio between the Ag sheet and Ag surface finish. This study systematically investigated the mechanism of bonding strength in extremely low-temperature pressure Ag sinter bonding, considering the relationship between microstructures and mechanical behaviors.