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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2879

    Title: 高功率發光二極體於自然對流環境下之熱流場分析;Thermal-Fluid analysis of HBLEDs under the natural convection
    Authors: 葉隆興;Long-Sing Ye
    Contributors: 機械工程研究所
    Keywords: 電子封裝散熱;熱流數值分析;有限元素法;LED熱阻量測;Thermal-Fluid Analysis;FEM;Rth Measurement
    Date: 2007-07-05
    Issue Date: 2009-09-21 11:59:06 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 能源短缺及溫室效應等議題,是世界各國在目前甚至是未來的五十年內所需面臨的問題。其中,傳統照明光源(白熾燈、日光燈)直接或間接造成了能源消耗。相較之下,在LED能達到150 lm/W的前提下預估可有效的降低這些問題。然而,材料匹配與應用、電路配置與電力之供應以及封裝材料散熱結構設計等等都直接的阻礙了此目標,其中又以散熱問題最為嚴重。因此,有效的熱管理是必要的。 本研究藉由熱阻量測系統的建立再配合數值分析軟體的應用,針對高功率LED在不同的操作條件下進行實驗及模擬分析,進而找出較適當的基板結構設計及操作條件,以降低整體熱阻及接面溫度。由數值方法模擬出之元件外部熱流場可得知,因特殊的幾何結構、輸入功率(大於1W)及自然對流環境,使得元件擺置角度角度於水平MCPCB基板朝下時,LED元件上方有二次流動的現象產生。當元件擺置角度於垂直方向時的自由流速較水平方向增加近2倍的流動速率,接面溫度及熱阻分別約降低4℃及2.4℃/W,又由於基板結構的改變(切槽及開孔設計),使得LED基板在水平擺置角度時,接面溫度及熱阻分別約降低4℃及4℃/W,而模擬與實驗結果比對後之準確率達90%。另外,本研究完成標準熱阻量測系統之建立,並與業界量測結果比對後有約有98%的相似率,並透過實驗方式歸納出適用於LED之對流熱傳係數估算經驗公式,期望本研究能作為日後設計時參考指標與努力方向。 In the 21st century, lack of energy or greenhouse effect has become one of top ten problems not only in global but also in many countries for next 50 years in which light is one of main reason that takes a high number of total energy consumption with traditional light equipments like fluorescent lamp and incandescent bulb etc…. When LEDs is invented, it has been used in many fields of living and industry in order to replace for foregoing light since it runs with high efficiency and save more energy. By the advanced technique at moment, it can be expected to reach over 150lumens/W, and as a result it reaches to the luminous efficiency. Because of this, it is essential to study the heat problems as well as the effective of thermal management for white light LEDs. In this study, the Measurement System of Thermal Resistance and Numerical Analysis Module have been done via experiment and simulation analysis in which focus on the high power LEDs at different work conditions in order to find out better MCPCB structure design and operated condition, that for the purpose of reduce the thermal resistance and junction temperature. In numerical simulation of the LED device outside thermal-fluid field, there is phenomenon of secondary flow that emerges above LED device when keep the horizontal downward of MCPCB, the velocity of free flow in the vertical angle orientation of device increased nearly 2 times of the efficiency than the horizontal, and the junction temperature as well as the total thermal resistance reduce around by 4℃ and 2.4℃/W respectively. In addition, due to the change of the structure of the substrate(slice, via…), junction temperature as well as the total thermal resistance reduce around by 4℃ and 4℃/W respectively. Simulation results are accurate more than 90% if compare to the experimental results. On the other hand, in this study the Standard Measurement System of Thermal Resistance has been finished that results are similar and closed to 98%compare with the industry and define the thermal convection coefficient correlation module of LED device by experiment data. These results may give the directions for LED’s design in the future.
    Appears in Collections:[機械工程研究所] 博碩士論文

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