Integral micro-channel liquid cooling for power electronics

A novel integral micro-channel heat sink was developed, featuring an array of sub-millimeter channels fabricated directly in the back-metallization layer of the direct bond copper or active metal braze ceramic substrate, thus minimizing the material between the semiconductor junction and fluid and the overall junction-to-fluid thermal resistance. The ceramic substrate is bonded to a baseplate that includes a set of interleaved inlet and outlet manifolds for uniform fluid distribution across the actively cooled area of the heat sink. The interleaved manifolds greatly reduce the pressure drop and minimize temperature gradient across the heat sink surface. After performing detailed simulations and design optimization, a 200 A, 1200 V IGBT power module with the integral heat sink was fabricated and tested. The junction-to-fluid thermal resistivities for the IGBTs and diodes were 0.17°C*cm²/W and 0.14°C*cm²/W, respectively. The design is superior to all reported liquid cooled heat sinks with a comparable material system, including the micro-channel designs. It is also easily scaleable to larger heat sink surfaces without compromising the performance.