Novel substrates for improved cooling of power electronics

Abstract

The thermal management of power electronics is critical to the long term reliability of these devices. In this work, three concepts which allow the placement of advanced cooling solutions close to power electronic die are investigated through the creation of advanced substrate technologies. First, two phase cooling was integrated with direct bonded copper power substrates by sintering copper particles directly onto the back side to allow for evaporative two phase cooling. The work experimentally investigated the impact of the thickness of the copper microporous layer as well as its size relative to the thermal test die on the heat transfer performance. The second methodology developed a novel substrate that replaces the DBC by having a cold plate with integrated AlN dielectric and circuit layer. A low-cost bonding method which created a low thermal resistance composite bonding layer was developed and demonstrated which allows low thermal resistance between the die and the cooling fluid. Finally, a third technique which uses a glass interposer with copper vias to bond the power die was investigated as a third packaging methodology. This strategy was explored through finite element analysis. Overall, this thesis presents several new pathways to improving the thermal management of wide bandgap power electronic and RF devices.