Thermal Design Methodology for an Embedded Power Electronic Module Using Double-Sided Microchannel Cooling

Abstract

This paper presents a thermal design methodology for an integrated power electronic module (IPEM) using embedded, single-phase, and laminar-flow rectangular microchannels. Three-dimensional packaging of electronic components in a small and compact volume makes thermal management more challenging, but IPEMs also offer the opportunity to extract heat from both the top and the bottom side of the module, enabling double-sided cooling. Although double-sided cooling of IPEMs can be implemented using traditional aluminum heat sinks, microchannels offer much higher heat transfer coefficients and a compact cooling approach that is compatible with the shrinking footprint of electronic packages. The overall goal of this work was to find the optimal microchannel configuration for the IPEM using double-sided cooling by evaluating the effect of channel placement, channel dimensions, and coolant flow rate. It was found that the high thermal conductivity copper of the direct bonded copper (DBC) layer is the most feasible location for the channels. Based on a new analytical heat transfer model developed for microchannels in IPEM structures, several design configurations were proposed in this study that employ the microchannels in the copper layers of the top and bottom DBCs. The designs included multiple parallel channels in copper as well as a single wide microchannel. The analytical model was verified using a finite element model, and the competing design configurations were compared against a commercial cooler. For a typical IPEM structure dissipating on the order of 100W of heat, it was concluded that a single microchannel DBC heat sink is preferable to multiple parallel channels under a double-sided cooling configuration, considering thermal performance, pressure drop and fabrication trade-offs.