Robust bonding at 175°C of pressureless Ag nanoparticle sinter joint on Ni/Au finished Cu substrates in air

Ag sinter joining which has exceptional characteristics is promising as a die-attach material for wide band-gap (WBG) power devices in electric vehicles (EVs). So far, many Ag sinter joining technologies in the range of 250 °C to 300 °C have been developed, but the industry still requires lower die-attach temperatures and more accessible processing methods. We have been pursuing technology that minimizes die-attach temperature and pressure to minimize the warpage of the power module structure. In this work, a pressureless Ag sintering was carried out in air at 175 °C without any pressure, and the bonding strength achieved approximately 37 MPa. The robust bonding mechanism of the Ag sinter joining was investigated using EBSD and XRD analysis on the microscale. This study can provide a solution for the possibility of the diebonding process at 175 °C and effective heat dissipation design of the power module.