Renewable Energy Global Innovations features: Enhancement of heat dissipation of LED module with cupric-oxide composite coating on aluminum-alloy heat sink

Significance Statement

Heat dissipation using thermal radiation is a novelty and clean method to energy conversion technology in electronics and mechanics. Most of the heat dissipation methods have been developed based on the principle of conduction and convection, whereas radiative heat transfer has not been considered because the emissivity of metallic aluminum surface is relatively low, approximately 0.1 ~ 0.2.  In the context of LEDs, various approaches, such as solder, thermal interface materials and metal-core printed circuit boards (MCPCBs), have been used to solve the heat dissipation problems.

 Our research group have been studied about more effective method for heat dissipation of LEDs, then the surface of aluminum alloy substrate was modified to increase the emissivity. The cupric oxide (CuO) has the higher emissivity in the whole materials around 0.96, a various distribution of particle size was implemented to evaluate the heat dissipation performance. Thermal resistance, emissivity, and continuous operation were carried out to investigate the possibility that a suitable coating layer of low thermal resistance can enhance the radiative heat dissipation and hence the overall heat dissipation performance.

 Lower LED operating temperatures and thermal resistances indicate superior heat dissipation performance. The significantly improved heat dissipation performance of the LED system was achieved by applying a composite coating with high radiative emissivity on an aluminum-alloy heat sink. The composite coating was composed of CuO nano-powders and silicon-based resin, having the thermal emissivity of ∼0.9 which is nine times greater than that of bare aluminum. The densely-coated composite layer with the enhanced the thermal emissivity of the surface improved the radiative heat dissipation significantly, enabling to reduce the thermal resistance of the heat sink and hence the total thermal resistance of the LED module up to ∼15%. Coating thickness affected the heat dissipation performance of the heat sink. In this study, the coating thickness of ∼200 μm showed the best performance. The composite coating, having the emissivity close to a black body, not only reduced the operating temperature of the LED chip but also allowed the stable heat dissipation with no significant degradation of the performance even under the elongated operation time. In conclusion, the use of a CuO-composite coating on a heat sink provides an effective means of enhancing radiative heat dissipation and increasing the LED life-time. 

About The Author

Donghyun Kim received his bachelor (2011), master, and doctoral (2016) degree in Department of Materials Science and Engineering (Nano-electrochemistry Lab) at Pusan National University, South Korea. His research field is “Electrochemistry”, “Wet Surface Treatment”, and “Heat dissipation via Thermal Radiation”. He published lots of paper about electrochemical surface and thermal radiation performance in SCI(E) journal.

About The Author

Wonsub Chung is currently a Professor in Department of Materials Science and Engineering at Pusan National University. He received his Ph. D. (1989) at Kyushu University, major is a chemical metallurgy. He teaches now “Corrosion and Anti-corrosion”, “Chemical Metallurgy”, and “Making Steel and Iron” and is a leader in Nano-electrochemistry Lab. In addition, his research is focused on thermal radiation performance, eco-friendly environmentally process, and wet surface treatment.  

Journal Reference

Energy Conversion and Management, Volume 106, December 2015, Pages 958–963.

Donghyun Kim¹, Junghoon Lee², Junho Kim³, Chang-Hwan Choi², Wonsub Chung¹

Show Affiliations

1. Department of Materials Science and Engineering, Pusan National University, Busan 46241, South Korea
2. Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
3. Korea Institute of Industrial Technology (KITECH), Busan 46742, South Korea

Abstract

A composite coating composed of cupric oxide (CuO) and silicon-based resin was applied to an aluminum-alloy heat sink for a light emitting diode (LED) module. The purpose of the composite coating is to improve the heat dissipation performance of heat sink by enhancing thermal radiation emission. The heat dissipation performance was investigated in terms of LED junction temperature and thermal resistance using a thermal transient method. The CuO and silicon-based resin composite coating showed higher emissivity, and the lower junction temperature and thermal resistance of the heat sink was achieved. In addition, a continuous operation test of the LED chip with the heat sink revealed that the surface treated with the CuO composite coating stably dissipated heat without degradation. In conclusion, the composite coating proposed here showed a significant improvement of the heat dissipation performance of the aluminum-alloy heat sink due to the enhanced thermal radiation property.

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