Feasibility Design of Tight Integration of Low Inductance SiC Power Module with Microchannel Cooler

Abstract

Traditional power module packaging becomes a limiting factor to fully exploit the benefits offered by high speed and high-temperature silicon carbide (SiC) devices. Especially in the automotive applications, the parasitic oscillation and localized hot spots have become unneglected problems. In this paper, an ultra-low inductance wire bondless power module with an integrated microchannel cooler is proposed. Flip-chip bonding with solder balls is used to replace traditional wire bonds to realize ultra-low inductance paths for both power- and gate-loop connections. As a result, the parasitic inductance of the proposed 1200 V, 300 A half-bridge SiC power module can be reduced to 0.93 nH. Then, to achieve high power density, an advanced low thermal resistance packaging architecture with an integrated microchannel cooler is proposed. Through femtosecond laser etching of the microchannels into the power module DBC ceramic layer, the microchannel cooler can be tightly embedded into the power module, resulting in a very high cooling capability. This method drives the module junction-to-coolant thermal resistance down to 0.073 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ·K/W, which leads to approximately 65% reduction of thermal resistance compared with the conventional cooling integration structure. Moreover, a corresponding fabrication process is developed to enable the tight integration of the microchannel cooler structure.