High Temperature Resistant Packaging Technology for SiC Power Module by Using Ni Micro-Plating Bonding

摘要

New bonding technologies, which can deliver high-temperature thermal resistance that replaces solder bonding or Al wire bonding, have been strongly expected in order to maximize the performance of SiC power device. Aiming for application to the inverter system of HEV and EV, we have developed a new micro-plating interconnection technology named Nickel Micro Plating Bonding (NMPB), which enables the interconnection in a narrow space between electrodes and SiC devices via our newly designed lead frame, whose lead surface is formed into chevron shape. As for the bonding strength of NMPB, it was confirmed by shear tests that the bonds showed higher bonding strength than ordinary Pb free solder die bonding and no degradation even after HTS at 250°C for 1000hrs and after 1000cycle TCT(250°C/-45°C). The NMPB was applied to the manufacture of one leg SiC inverter power module using two pairs of SiC MOS-FETs and SBDs, which were interconnected with a newly designed lead frame for double sided cooling structure. After molding resin copper heat spreaders were formed on the outer surfaces of both sides of the NMPB leads by additive method. The module showed stable I-V characteristics at 250°C and lower switching loss. The reliability of the modules was confirmed by TCTs and power cycle tests.