Zhang Kai

The Hong Kong University of Science and Technology, Kowloon, Hong Kong

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Publications (2)0 Total impact

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    ABSTRACT: With more and more high power high brightness LEDs adopted in general lighting applications, the state-of-the-art packages cannot meet the requirement of thermal management. Over-heating of an LED will cause premature failure because the efficiency, the spectrum, the reliability and the life of solid state lighting devices strongly depend on successful thermal management. Therefore, the requirement for improving the performance and the reliability poses a significant challenge for novel cooling solutions including applications of heat sinks with active cooling methods and high thermal performance materials. Conventional mechanical fans are not preferred in LED devices due to its high energy consumption, short life and high noise. In this study, cooling fixtures with piezoelectric units are designed to be integrated with high power LED modules. The cooling effect of high performance TIM and piezoelectric units are investigated using numerical modeling method.
    Electronic Packaging Technology and High Density Packaging (ICEPT-HDP), 2011 12th International Conference; 01/2011
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    ABSTRACT: Vertically aligned carbon nanotube (VACNT) arrays were synthesized directly on aluminum alloy substrates by thermal chemical vapor deposition (CVD). Iron nitrate (Fe(NO<sub>3</sub>)<sub>3</sub>ldr9H<sub>2</sub>O) was used as the catalyst. Parameters influencing CNT synthesis were studied and optimized. Several surface treatment methods were proposed to improve the quality of CNTs synthesized on aluminum alloy substrates. The grown CNT arrays were used as thermal interface material (TIM) while the aluminum alloy substrate used as the heat sink in high brightness LED packages. The measured thermal resistance of the grown CNT-TIM was 38 mm<sup>2</sup>-K/W. The output light power testing demonstrated CNT-TIM is an attractive thermal management solution for HB- LED packages.
    Electronic Components and Technology Conference, 2008. ECTC 2008. 58th; 06/2008