近年來LED發光效率逐漸提升，應用的產品也由傳統指示燈轉變為背光照明用途。由於LED的接面溫度限制較低，故熱量多以傳導與對流形式向外釋出。隨著驅動電流的增加，LED封裝形式的熱管理也逐漸受到重視。而建立一條暢通的散熱途徑，可維持LED接面溫度在容許的範圍內，以確保元件的可靠度。
本研究使用有限體積分析軟體Flotherm對高功率LED模擬熱場分析，分別探討Luxeon LED內部Slug面積與厚度間之關係及四種PCB基板對整體散熱效益之影響。結果顯示，欲將接面溫度降至120℃以下，1W與2W的LED所需Slug面積不得小於25、70mm2。而厚度在2~4mm時有較低的熱阻值。簡化介電層層數與使用高導熱性銲錫取代導熱膠能有效改善溫度變化劇烈的現象，有效提昇散熱效益。實驗部份紀錄LED重複啟動後，在固定電流400mA的條件下，紅光電壓下降0.4V，晶片表面上升6.2℃；綠光電壓下降0.4V，晶片表面上升9.1℃。

Light Emitting Diodes (LEDs) have progressed from being indicators to general and back lighting applications in recent years due to increase of their emitting efficiency. LED junction temperatures are considerably lower than those of light bulbs and hence the heat transfer mechanism depends on conduction and convection primarily. With the increased electrical currents, the thermal managements have been focused in developments of LED packaging. A good thermal path can help an LED chip to OK its junction temperature low to maintain the reliability of LED.
A finite volume method package (Flotherm) is used to analyze the temperature field of the high power LEDs. Both package and system level thermal managements are discussed. The junction temperature of 120℃ can be obtained. Packages with the slug of 25 and 70 mm2 in cross sectional areas, 2~4mm thick for 1W and 2W’s LED, respectively, with the same cooling system. By removing the dielectric layers and using solder in place of epoxy can lower the junction temperature. Experimental results show that the voltages of the red and green LEDs decrease 0.4 Volt with a fixed current of 400mA. The surface temperatures of the red and green LED increase 6.2℃ and 9.1℃.

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