@article{a8c54e846fad493dad1d8974416a40ae,
title = "An integrated liquid metal thermal switch for active thermal management of electronics",
abstract = "Heat dissipation is a key obstacle to achieving reliable, high-power-density electronic systems. Thermal devices capable of actively managing heat transfer are desired to enable heat dissipation optimization and enhanced reliability through device isothermalization. Here, we develop a millimeter-scale liquid metal droplet thermal switch capable of controlling heat transfer spatially and temporally. We demonstrate the thermal switch by integrating it with gallium nitride (GaN) devices mounted on a printed circuit board (PCB) and measure heat transfer and temperature of each device for a variety of switch positions and heat dissipation levels. When integrated with a single GaN device (2.6 mm × 4.6 mm face area) dissipating 1.8 W, the thermal switch shows the ability to actively control heat transfer by conducting 1.3 W in the ON mode with the GaN device at 51 °C ± 1 °C, and 0.5 W in the OFF mode with the GaN device at 95 °C ± 1 °C. To elucidate the heat transfer physics, we developed a 1-D system thermal resistance model in conjunction with an independent 3-D finite-element method (FEM) simulation, showing excellent agreement with our experimental data. Finally, we demonstrated that when the switch is integrated with two GaN devices, the switch can balance the device heat transfer rate and enhance junction temperature uniformity and system reliability by lowering the device-to-device temperature difference from > 10 °C (no switch) to 0 °C.",
keywords = "Active thermal management, Galinstan, gallium nitride (GaN), isothermalization, liquid metal, power electronics, reliability, thermal switch",
author = "Tianyu Yang and Thomas Foulkes and Beomjin Kwon and Kang, {Jin Gu} and Braun, {Paul V.} and King, {William P.} and Nenad Miljkovic",
note = "Funding Information: Dr. Kang was a recipient of the Kwanjeong Educational Foundation Scholarship. Funding Information: Manuscript received February 6, 2019; revised May 18, 2019; accepted June 25, 2019. Date of publication July 19, 2019; date of current version December 6, 2019. This work was supported by the National Science Foundation Engineering Research Center for Power Optimization of ElectroThermal Systems (POETS) under Cooperative Agreement EEC-1449548. The work of T. Foulkes was supported by the National Science Foundation Graduate Research Fellowship Program under Grant DGE-1144245. The work of N. Miljkovic was supported by the International Institute for Carbon-Neutral Energy Research, Kyushu University, through the Japanese Ministry of Education, Culture, Sports, Science and Technology, under Grant WPI-I2CNER. Recommended for publication by Associate Editor B. Barabadi upon evaluation of reviewers{\textquoteright} comments. (Corresponding authors: William P. King; Nenad Miljkovic.) T. Yang, W. P. King, and N. Miljkovic are with the Department of Mechanical Science and Engineering, University of Illinois at Urbana– Champaign, Urbana, IL 61801 USA (e-mail: tianyuy2@illinois.edu; wpk@illinois.edu; nmiljkov@illinois.edu). Funding Information: This work was supported by the National Science Foundation Engineering Research Center for Power Optimization of Electro- Thermal Systems (POETS) under Cooperative Agreement EEC-1449548. The work of T. Foulkes was supported by the National Science Foundation Graduate Research Fellowship Program under Grant DGE-1144245. The work of N. Miljkovic was supported by the International Institute for Carbon- Neutral Energy Research, Kyushu University, through the Japanese Ministry of Education, Culture, Sports, Science and Technology, under Grant WPII2CNER. Publisher Copyright: {\textcopyright} 2011-2012 IEEE.",
year = "2019",
month = dec,
doi = "10.1109/TCPMT.2019.2930089",
language = "English (US)",
volume = "9",
pages = "2341--2351",
journal = "IEEE Transactions on Components, Packaging and Manufacturing Technology",
issn = "2156-3950",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "12",
}