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High-efficiency cooling via the monolithic integration of copper on electronic devices

Abstract

Electrification is critical to decarbonizing society, but managing increasing power densification in electrical systems will require the development of new thermal management technologies. One approach is to use monolithic-metal-based heat spreaders that reduce thermal resistance and temperature fluctuation in electronic devices. However, their electrical conductivity makes them challenging to implement. Here we report co-designed electronic systems that monolithically integrate copper directly on electronic devices for heat spreading and temperature stabilization. The approach first coats the devices with an electrical insulating layer of poly(2-chloro-p-xylylene) (parylene C) and then a conformal coating of copper. This allows the copper to be in close proximity to the heat-generating elements, eliminating the need for thermal interface materials and providing improved cooling performance compared with existing technologies. We test the approach with gallium nitride power transistors, and show that it can be used in systems operating at up to 600 V and provides a low junction-to-ambient specific thermal resistance of 2.3 cm2 K W–1 in quiescent air and 0.7 cm2 K W–1 in quiescent water.

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Fig. 1: Cu-coated heat spreader fabrication.
Fig. 2: Photographs of the tested configurations.
Fig. 3: Thermal performance of EPC2034 monolithically integrated with copper.
Fig. 4: Heat-spreading analysis.
Fig. 5: Coating effect on thermomechanical reliability.

Data availability

Data supporting the findings of this study are available at https://zenodo.org/record/6471515#.Yl8-v-jMLHo. All other data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

MATLAB, Ansys Static Structural and Ansys Icepak input files generated for this work are available at https://zenodo.org/record/6471515#.Yl8-v-jMLHo. All other files that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We gratefully acknowledge funding support from the Advanced Research Projects Agency-Energy (ARPA-E) with cooperative agreement no. DE-AR0000900. N.M. and T.G. gratefully acknowledge funding support from the Power Optimization of Electro-Thermal Systems (POETS) National Science Foundation Engineering Research Center with cooperative agreement no. EEC-1449548. T.G. gratefully acknowledges funding support from a PPG-MRL assistantship. N.M. gratefully acknowledges funding support from the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology. We thank S. Robinson of the Microscopy Suite at the Beckman Institute for Advanced Science and Technology (part of the University of Illinois at Urbana-Champaign) for help with thermal evaporation. Laser scanning confocal microscopy, scanning electron microscopy, four-point probe and parylene C coating were carried out in part at the Materials Research Laboratory’s Central Research Facilities, University of Illinois.

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T.G. and N.M. conceived the initial idea and designed the experiments. T.G., J.L. and J.M. fabricated the samples and carried out the material characterization. T.G., A.R.G., J.M., N.M., J.S., L.H. and R.P.-P. performed the experimental and theoretical analyses and wrote the manuscript. R.P.-P. and N.M. edited the manuscript and guided the work.

Corresponding author

Correspondence to Nenad Miljkovic.

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Nature Electronics thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary Sections 1–11, Tables 1–18, Figs. 1–11 and refs. 1–40.

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Gebrael, T., Li, J., Gamboa, A.R. et al. High-efficiency cooling via the monolithic integration of copper on electronic devices. Nat Electron 5, 394–402 (2022). https://doi.org/10.1038/s41928-022-00748-4

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