Low temperature bonding with high shear strength using micro-sized Ag particle paste for power electronic packaging

Bonding technology using a Ag nanoparticle paste has been a promising substitute for high-Pb-containing solder joining. However, it has some drawbacks, such as high cost and low compatibility, due to its high sintering temperature. Recently, the bonding process using the micro-sized Ag particle paste has been studied for cost-effectiveness, but it is limited in terms of high applied pressure or relatively low joint strength. In this study, a low pressure of 0.4 MPa was applied during bonding by micro-sized Ag particle paste for lower bonding temperature and higher joint strength. The micro-sized Ag paste was composed of chestnut-burr-like and spherical particles. Under low applied pressure, the joint with a high shear strength of 54.6 MPa was achieved when the bonding temperature and time were 260 °C and 10 min, respectively. It was also possible to reduce the bonding temperature and time for the joints having similar strength to that of the pressureless process. The microstructure showed a linear relationship to the shear strength, regardless of the bonding conditions.