Pressureless Silver Nanopowder Sintered Bond for Liquid Cooled IGBT Power Module for EVs and HEV

Pressureless silver nanopowder sintering of the bonding layer between the insulated gate bipolar transistor (IGBT) and the direct bonded copper (DBC) for the liquid cooled power modules in electric vehicles and hybrid electric vehicles is studied. The pressureless silver nanopowder sintering is analysed using the Differential Scanning Calorimeter / Thermogravimetry / Simultaneous Thermal Analysis and the Scanning Electron Microscopy. Based on the analysis results, the sintering is optimized at 200 °C for 60 minutes for reliable die attachments. The bonding of the sintered silver to the IGBT is confirmed by intermetallic layers composition analysis. The nanopowders are classified by the average sizes into the micro and nano-meter scaled groups. The porosity of 30% is computed within the sintered silver layer. Overall, the experimental results verify the feasibility of the pressureless silver nanopowder sintering of the bonding layer between the IGBT and the DBC.