發光二極體的操作溫度之討論

Study of LED Operating Temperature

黃兆中(Chao-Chung Huang)

指導教授 ： 陳隆建

國立臺北科技大學/電資學院/光電與能源產業研發碩士專班/碩士(2011年)

摘要

由於高功率LED輸入功率約有15~20%轉換成光，其餘80~85%的輸入功率則轉換成熱，若熱能無法正常排出至外界，將會導致LED晶粒接面溫度過高而影響發光效率及發光壽命。若能有效地量測LED的接面溫度(junction temperature)，將可使LED製造商研發製造更有發光效率及散熱更佳的高功率LED，故本文將探討操作溫度對發光二極體的影響。
本文使用兩種可測量發光二極體接面溫度儀器，分別為Acorn Technology LED Junction Temperature Tester及Fluke Ti25 Ti 25 Infrared IR Thermal Imaging Camera Imager，測量三種不同條件(散熱基板)下之LED 溫度，依序為(1) 未加散熱基板；(2) 使用鋁基板；(3) 使用銅基板。
由量測結果可以看到當溫度大過基板的散熱能力的時候，紅外線熱像儀測得的溫度就會比接面溫度測試儀來的低，這是因為熱全部集中在LED晶片，故要測量LED的接面溫度必須使用接面溫度測試儀較為準確度較高，且也不易受外界因素影響。此外，由結果顯示，欲降低LED的接面溫度，必須從LED封裝階段就要考慮其散熱問題，由於散熱模組負責最後將熱傳至空氣中，因此散熱模組散熱的效能將決定LED元件散熱的能力，且可提升LED的發光效率與壽命。

關鍵字

發光二極體 ； 操作溫度

並列摘要

Because of the high-power LED input about 15 ~ 20% of power into light, and the 80 to 85% of power is converted into heat. The luminous efficiency and the lifetime of chip will decrease at the high temperature condition. If we can effectively measure the interface temperature (junction temperature) of the LED, the LED manufacturers will be able to make luminous effective, better heat dissipated and high power LED. This article explains operating temperature impacts on light-emitting diodes.
This test using two interfaces measures check the temperature of light-emitting diode , Acorn Technology LED Junction Temperature Tester and the Fluke Ti25 Ti 25 Infrared IR Thermal Imaging Camera Imager, measuring LED temperature in three different conditions (cooling substrate) , (1) substrate without additional heat; (2) the use of aluminum plate; (3) the use of copper substrates.
The measurement results show if the temperature is greater than the substrate heat conductivity, the temperature that measured by infrared IR thermal imaging system is lower than the temperature that measured by Junction Temperature Tester , Because of the heat concentrated in the LED chip, using Junction Temperature Tester will be more accurate for checking the LED interface temperature. The test result also shows, in order to lower the interface LED temperature, the heat dissipation problem must be considered from LED beginning packaging stage. The thermal module efficiency is responsible for the final heat conductivity, it will determine the efficiency of LED device, and enhance the LED luminous efficiency and lifetime.

並列關鍵字

LED ； Operating Temperature

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