Investigation of Pressure Assisted Nanosilver Sintering Process for Application in Power Electronics

Abstract

High power electronics with wide band gap semiconductors are becoming the most promising devices in new energy power suppliers and converters. Highly reliable die attach materials, serving as one of interconnections, play critical roles in power electronic packages and modules. Among which, the nanosilver paste/film has become a promising die attach material with main advantages of a high thermal and electrical conductivity, as well as high temperature stability. Previous works are mostly focusing on the pressure free sintered silver nanoparticles, which has a low bonding strength and high porosity. Alternatively, pressure assisted sintering has exhibited great advantages in enhancing the bonding quality of nanosilver sintered joint. But the sintering properties of pressure sintered silver nanoparticles and the application of this technology in power electronics packaging are still lacking. In this thesis, a comprehensive research is performed on the pressure assisted sintering of silver nanoparticles. The results indicate that the sintering pressure demonstrates significant effect on enhancing the bonding strength of sintered silver nanoparticles. Furthermore, the increase of sintering pressure from 5 MPa to 30 MPa improves the resistance to plastic deformation and creep of nanosilver sintered joint. In addition, the designed nanosilver sintering technology is successfully employed in fabricating the double side sintered power package. Besides, the nanosilver sintering process is designed and employed in the ceramic packaging.