Liquid-Cooled Aluminum Silicon Carbide Heat Sinks for Reliable Power Electronics Packages

Abstract

With recent advances in the state-of-the-art of power electronic devices, packaging has become one of the critical factors limiting the performance and durability of power electronics. To this end, this study investigates the feasibility of a novel integrated package assembly, which consists of copper circuit layer on an aluminum nitride (AlN) dielectric layer that is bonded to an aluminum silicon carbide (AlSiC) substrate. The entire assembly possesses a low coefficient of thermal expansion (CTE) mismatch which aids in the thermal cycling reliability of the structure. The new assembly can serve as a replacement for the conventionally used direct bonded copper (DBC) - Cu base plate - Al heat sink assembly. While improvements in thermal cycling stability of more than a factor of 18 has been demonstrated, the use of AlSiC can result in increased thermal resistance when compared to thick copper heat spreaders. To address this issue, we demonstrate that the integration of single-phase liquid cooling in the AlSiC layer can result in improved thermal performance, matching that of copper heat spreading layers. This is aided by the use of heat transfer enhancement features built into the AlSiC layer. It is found that, for a given pumping power and through analytical optimization of geometries, microchannels, pin fins, and jets can be designed to yield a heat transfer coefficients (HTCs) of up to 65,000 W m-2 K-1, which can result in competitive device temperatures as Cu-baseplate designs, but with added reliability.