多晶片COB封裝之高功率LED的散熱分析

Heat Dissipation Analysis of High Power Multi-Chip COB Package LEDs

本研究比較五種不同晶片間距之「多晶片 （chip on board, COB） 封裝之高功率LED 元件」的晶片溫度 （chip temperature, Tchip） 及熱阻 （thermalresistance, Rth），以評估LED 的散熱效能。實驗除了以紅外線熱顯像儀實際測量晶片溫度，並使用計算流體力學軟體 （computational fluid dynamics, CFD） 進行模擬比對。此外也探討不同材質散熱基板、不同散熱鰭片厚度以及不同晶片尺寸對於COB 封裝高功率LED 元件晶片溫度的影響。結果顯示消耗功率為9.92 W （350 mA） 時，A、B、C、D 及E Type 試片的晶片溫度分別是84.32°C、82.87°C、81.91°C、81.36°C 與81.20°C，晶片間距最小的A Type 與最大的EType，兩者的晶片溫度相差3.12°C，顯示晶片間距較小者具有較高的晶片溫度以及熱阻，當GaN-base晶片的間距從0.5 mm增加至2.0 mm時，可以有效地將晶片產生的熱能傳導出來。

Five different chip gaps of multi-chip COB (chip on board) packagesof high power LED components were compared chip temperature andthermal resistance to evaluate the thermal performance of LEDs in thisstudy. The junction temperature was measured not only by using an IRcamera but also the Computational Fluid Dynamics (CFD) simulationsoftware for comparison. Furthermore, the effects of different heat slugs,the thickness of heat sinks and chip size on the junction temperature ofhigh power LED components were discussed. Experimental results showthat for power consumption of 9.92 W (350 mA) the chip temperature of A, B, C, D and E-Type structure was 84.32°C, 82.87°C, 81.91°C, 81.36°C and81.20°C, respectively. The chip temperature difference between theA-Type and E-Type structure was 3.12°C. Thus, a chip with a smaller gapa higher chip temperature and more thermal resistance. The gap of aGaN-base chip increased from 0.5 mm to 2.0 mm, resulting in an efficientincrease in heat dissipation.