Comparative study of nickel-tin and copper-tin transient liquid phase bondings for power electronics packaging

摘要

Recently, the eco-friendly vehicles such as Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) have been spotlighted. EV has power semiconductors which generate a lot of heat. So, the power semiconductors have to guarantee reliability because it is driven at high temperature. Furthermore, it was able to be driven at a higher temperature by developing the semiconductor devices such as SiC and GaN. Thus, power electronics packaging requires die-attach methods which have reliability and are suitable at high temperature. Vehicles also require long life-time to use 5 to10 years. Therefore, in this study, Transient Liquid Phase (TLP) bonding technology was studied as high temperature die-attach method. TLP bonding technology is suitable at high temperature but require reliability verification. For this reason, we performed the TLP bonding process to evaluate the possibility of the method for high power applications. We compared Cu-Sn to Ni-Sn TLP bonded joints in this study. We first evaluated the interfacial reaction and transformation of solder (Sn) to intermetallic compound (IMC) phase according to different bonding conditions. IMC phases in the TLP bonded joints were observed by SEM. In addition, the distribution and transformation of IMC phases were analysed by EDS element mapping method.