Low Temperature Ag Sintering and Driving Force on Au Finished Cu Substrates at 145°C and 175°C Using Ag Nano-Porous Sheets without Organic Solvents

This study investigated the die bonding process with an Ag nano-porous sheet, which eliminates the necessity for organic solvents, reducing the inefficient procedures associated with the current Ag paste sintering process. We evaluated the low temperature sinter bonding at 145°C, which is the lowest temperature known to be “theoretically” possible for Ag sintering. In particular, it is interesting to note that sintering was successfully achieved between Au finished Cu substrates and Ag nano-porous sheets. Consequently, we achieved shear strength of approximately 12 MPa (i.e., bonding temperature of 145°C) and 22 MPa (i.e., bonding temperature of 145°C) with a bonding time of only 10 min. The fundamental attribution of bonding strength was to the interfacial connected ratio between the Au finished surface and the Ag nano-porous sheet. This study systemically investigated the bonding mechanism in extremely low-temperature Ag-Au sinter bonding, with a focus on the relationship between microstructures and the resulting mechanical behaviors.