Browsing by Author "Zhang, Wen-Hua"

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A NOVEL LIQUID-PACKAGING TECHNOLOGY FOR HIGHLY RELIABLE UV-LED ENCAPSULATION
(2019-01-01)
Zhang, Wen-Hua
;
Lin, Wei-Keng
;
Yeh, Chih-Ting
;
Chiang, Song-Bor
;
Jao, Chih-Sheng
This paper proposes a liquid-packaging technology for UV LED. Unlike the traditional packaging methods that involve thermosetting silicon or quartz glass, the proposed method primarily uses silicon oil to directly contact the chip, which prevents erosion due to moisture or oxygen. In this study, UV LEDs with high heat dissipation technology were selected, and the experimental results of optical and thermal management were compared between the general packaging and liquid-packaging structures, respectively. The results of the optical experiments showed that the proposed method increases the extraction efficiency by 9.5%. The results of the heat dissipation experiments showed that the liquid-packaging technology can reduce the thermal resistance of the UV-LED package by 31%.
A novel oxidized composite braided wires wick structure applicable for ultra-thin flattened heat pipes
(2017-11-01)
Yang, Kai-Shing
;
Tu, Cheng-Wei
;
Zhang, Wen-Hua
;
Yeh, Chih-Ting
;
Wang, Chi-Chuan
This present study proposed a novel low-cost and high performance braided wire wick structure having superhydrophilic treatment applicable for ultra-thin heat pipe. The test wick structures include mono and composite wick structure. The composite braided wire adopts two different diameter wire design, using a large diameter (0.1 mm) in the core while the exterior of the core is covered by smaller diameter copper wire (0.05 mm). The mono design contains only one uniform wire diameter (0.1 mm) in core region. Test results indicate that via oxidizing the surface of the braided wires can largely enhance the surface roughness and result in a much higher capillary force as comparing to the un-oxidized one. In addition, both mono (m-FHP) and composite braided wire (c-FHP) with oxidization could possess a maximum heat transfer capability over 15 W under horizontal operation, and test results showed that the heat transfer capability of composite design outperforms mono one by more than 32.5% in all orientations. It is also found that the filling loading ratio plays essential role on the overall performance of FHP. Either a low filling loading ratio or a high filling loading ratio may yield a lower maximum heat transfer capability and a higher thermal resistance. An optimum filling loading ratio of 125% yields the lowest thermal resistance around 0.12 K/W with the best heat transfer capability of 20W.