Nanoparticle/solder hybrid joints for next-generation power semiconductor modules

The properties of hybrid joints between SiC chips and direct-bond Cu (DBC) plates, which were composed of Cu nanoparticles and eutectic Bi-Sn solder particles, have been examined. The produced bonding layer contained metallic Cu, Cu-Sn compounds, and metallic Bi species. The interfacial region of the bonding layer along both the SiC chip and DBC plate was formed by wetting of Bi. The hybrid joint exhibited >30MPa of bonding strength without applying high pressure. The bonding strength is higher than that of conventional Cu nanoparticle joints, and exhibited a lower dependence on the need for additional pressure during firing. The bonding strength was also higher than that of Pb-based solder joints measured at temperatures as high as 498K, although it decreased with the testing temperature. The obtained results indicate that the proposed hybrid bonding method enables a low pressure process of soldering and results in a high heat resistance of nanoparticle joints, which is required for packaging next-generation power semiconductor modules.