發光二極體最佳化散熱模組研究

A Study of LED Optimum Thermal Module

陳楨鈺(Chen-Yu Chen)

指導教授 ： 蘇艾

元智大學/工程學院/機械工程學系/碩士(2007年)

摘要

本文實驗研究三原色發光二極體與白光發光二極體的特性，以及白光發光二極體發熱功率與散熱座面積之關係，藉此設計最佳的組合比。實驗得知，三原色LED的電性特性中，紅光晶粒的內電阻值較低，藍綠光的電性特性相近。三色光的發光特性，等同輸入電功率條件下，綠光的照度結果最高，藍光的照度值僅約為綠光的1/5。單位面積發光能量，藍綠光結果相近，紅光為最高，約為藍綠光的3.5倍。三色光晶粒，尤以紅光晶粒受外部環境溫度影響最明顯，當基板溫度升高25℃時，紅光照度減少約12％，藍綠光照度下降約2∼3％。
白光發光二極體實驗得知，晶粒之發光照度與光強度結果於溫度直接相關，此外其頻譜結果並未明顯受功率提升而產生色偏情形。對於功率使用範圍2W的RGB 白光LED而言，1W及3W晶粒各反應結果相近，5W有較佳的光效能結果，但三者溫度結果接近。不同合成白光方式之比較，同等功率條件YAG LED之發光性能高於RGB LED。
再由實驗結果得知LED輸入功率與必要之散熱面積值的關係曲線，以500cm2散熱面積散熱座為例，限制LED基板的最高溫度上限為70℃時，散熱座可容忍的最大輸入電功率值約為14.3W。散熱座與外部環境間的熱傳途徑，包含熱傳導及熱對流，當散熱鰭片表面溫度增高時，即增加熱對流熱傳效益。

關鍵字

發光二極體 ； 照度 ； 光強度 ； 散熱鰭片

並列摘要

Investigations of thermal characteristics of Red, Green, Blue LED and White LED and diffusion area for the LED module were conducted experimentally. Results show that red LED has lower internal resistance than that of green and blue. However, green LED shows higher luminous flux than the others. The luminous flux of blue LED is only one fifth than that of green LED, its lighting power energy is closed to green LED. In these three kinds of lighting LED, red LED is more sensitive to the thermal environment. Red lighting efficiency will decrease almost 12% when the substrate temperature increases 25℃.
From the White LED result, The luminous flux and UV Energy are relative to temperature, and the spectrum doesn’t have any departure. For 2W input power, 5W LED have better thermal characteristics .To compare different packaging LED, YAG LED have better effect than RGB LED on the same input power.
Thermal diffusion experimental results show a closed correlation between thermal power and diffusion area of module. If the up limit temperature of LED substrate is 70℃, for a 500 cm2 area, the higher limit of electric power is 14.3 watts. Diffusion processes for LED substrate to environment include thermal conduction and convection. Thermal convection will dominate as increasing surface temperature of thermal module.

並列關鍵字

LED(Light Emitting Diode) ； luminous flux ； UV Energy ； thermal module

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