Determination of the junction temperature of Gallium Nitride (GaN)-based high power LED under thermal with current loading conditions

This In recent years, high brightness with low power consumption green power device, Light emitting diodes (LEDs), has become more and more popular. In this highly competitive area, how to effectively let the LED product meet the spec requirements and shorten the design cycle becomes more and more important. Currently, the common reliability test of LED is according to IES LM80-08, which is time consuming and will prolong the time-to-market schedule. In our previous researches, a modified accelerated aging test algorithm which can shorten the testing time on high power LEDs using different high temperature stress without input current was successfully proposed. The effect of input current with temperature loading may have to consider in accelerated aging test. For the accelerated aging test with the loading conditions of temperature and current, this research proposed a methodology to simulate the junction temperature of the LED using finite element (FE) method with thermal theories. The junction temperature of LED chip can be obtained by JEDEC standard EIA/JESSD51-1, which is based on the forward voltage method, and the simulation result was validated with the experiment result. In summary, the predicted temperature would help the accelerated aging test essentially. It significantly reduced the try-and-error time in experiment. The model can simulate the junction temperature under working current in different ambient temperature. Based on this methodology, the simulation result would apply to the accelerated aging test with developed degradation prediction model in the future.