Pressureless Silver Nanopowder Sintered Bonds for Liquid Cooled IGBT Power Modules

Conference: CIPS 2018 - 10th International Conference on Integrated Power Electronics Systems
03/20/2018 - 03/22/2018 at Stuttgart, Deutschland

Proceedings: ETG-Fb. 156: CIPS 2018

Pages: 6Language: englishTyp: PDF

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Kim, Namjee; Li, Rophina; Ng, Wai Tung (The Edward S. Rogers Sr. Electrical and Computer Engineering Department, University of Toronto, Toronto, Ontario, Canada)
Machler, Meinrad; Burgers, John (Electronics/Battery Thermal Management, Dana Canada Corp. Oakville, Ontario, Canada)
Winkler, Sooky (Metallurgy Department, Dana Canada Corp. Oakville, Ontario, Canada)

An insulated gate bipolar transistor (IGBT) die attachment technique using pressureless silver nanopowder sintering on direct bonded copper (DBC) for liquid cooled heat sink is studied. Henkel (Loctite Ablestik SSP 2020-EN) silver paste is used, and its sintering process is optimized at 200 °C for 60 min with no pressure on the nickel and gold electroplated DBC substrate. A porosity of 29 % is obtained. Irregular shaped particles of micro-meter scale and nano-meter scale sizes are observed via scanning electron microscope (SEM). Differential scanning calorimeter (DSC) / thermogravimetry analysis (TGA) / simultaneous thermal analysis (STA) results indicate that the solvent starts to evaporate at 114 °C and reaches its peak at 133 °C. The temperature for sintering is set at 200 °C to minimize the thermal budget on the fabricated IGBT dies. The isothermal test indicates that a minimum sintering time of 40 min is required to promote sufficient diffusion of atoms. A sintering time of 60 min is found to provide reliable die attachments.