Near-junction cooling for next-generation power electronics

This article focuses on chip-scale single-phase cooling for high heat flux and high temperature power device operation. This technology is focused on future wide band-gap semiconductors, which are expected to survive harsh environments. To this end, strategies for near-junction cooling of vertical current power electronics devices are briefly reviewed, and two chip-scale coolers are experimentally investigated. Using single-phase water at an inlet temperature of 50 °C, a 40 mm × 20 mm straight microchannel (quantity 200, 38 μm × 313 μm) cooling chip is shown to dissipate up to 127.5 W/cm2 over a 1 cm2 area with a pressure drop of 40.2 kPa at 100 ml/min. A second 75% downsized 20 mm × 10 mm cooling chip based on a unique 500 μm × 500 μm unit cell microchannel plus jet impingement array architecture is then introduced. At the same inlet temperature and in single-phase operation, this chip-scale cooler is shown to dissipate up to 1.02 kW/cm2 over a 0.25 cm2 area. A maximum average heat transfer coefficient of 120.2 kW/m2K and a pressure drop of 81.2 kPa is further established at a 450 ml/min fluid flow rate. The unit cell jet impingement-based design is shown to additionally support average heater temperatures of 177.1 °C. Such technologies are anticipated to enable a 5-to-10-fold reduction in power package size when compared with traditional remote cooling strategies.