Woodruff School of Mechanical Engineering



Single-Phase Liquid Cooling for Thermal Management of Power Electronic Devices


Kenechi Agbim


Georgia Institute of Technology


Thursday, July 13, 2017 at 2:00:00 PM


MRDC Building, Room 3515


Courtney Aiken


Power electronic devices such as MOSFETs, HEMTs, and IGBTs often face reliability challenges due to poor thermal management during device operation at high power densities. Conventional power devices incorporate a silicon layer that has certain operational temperature limits (e.g 150C). Device operation beyond these limits can result in thermal runaway, thermal fatigue of the material, and delamination of the device substrate. These issues are largely due to the mismatch of the coefficient of thermal expansion (CTE) between the device material layers, and the build up of thermal stresses due to thermal cycling of these devices. To address the increase in device temperature with high heat fluxes, conventional power devices are often attached to a cold plate cooler using solder. However, this stack usually employs thermal interface material layers that have been found to increase the thermal resistance in the device package. This thermal resistance built in this stack limits the heat dissipation needed to maintain safe temperatures for the power devices. The integration of a liquid cooling technique has shown promise to significantly reduce (up to 2.3x) the thermal resistance in power electronic cooling systems as compared to the thermal resistance found using a conventional cold plate cooler design. Thus, the main objective of this work is to evaluate vertical (jet impingement) and horizontal (microchannel) cooling schemes with integrated cooling. The cooling systems in this work apply novel direct integration of cooling electronics (DICE) techniques, to reduce buildup of thermal resistance, enhance heat transfer through microstructure features integrated into the substrate material, and reduce the chip temperature in power electronic devices. For this work, each cooling method underwent a pseudo-optimization design analysis to identify the relevant contributors to the performance of the heat sink designs. Parameters such as pressure drop, pumping power, and heat transfer coefficient were used to assess industry and manufacturing tradeoffs associated with each design. Through experiments, the pressure drop, chip junction temperature, and inlet and outlet temperatures were measured. This presentation reviews both the horizontal and vertical cooling techniques that were tested and evaluated experimentally. To validate the experimental results, numerical and analytical models were developed to simulate the experimental environment. Heat flux conditions ranging from 1 W/m2 to 100W/m2 were applied to these test coupons, and the performance of each of the cooling schemes was evaluated.


Kenechi received her M.S. in Mechanical Engineering from Georgia Institute of Technology in 2017 and her B.S. in Mechanical Engineering and certificates in Nuclear Engineering and Product Realization from the University of Pittsburgh in 2014. Her research at Tech focused on thermal management of power electronics for efficient cooling in hybrid electric vehicles. In her undergraduate, she worked as a co-op and intern for Mine Safety Appliances, Westinghouse Electric Company, and was a research fellow through the Toshiba-Westinghouse Fellows Program. At the University of Pittsburgh, Kenechi became interested in developing systems to reduce fossil fuel dependence and she worked on projects implementing thermoelectric devices and semiconducting materials for use in efficient energy conversion processes. This research inspired her exploration of other areas of thermal management and energy conversion.


Refreshments will be served.