Abstract
Accelerated aging tests are the main method used in the evaluation of LED reliability, and can be performed in either online or offline modes. The goal of this study is to provide the difference between the two test modes. In the experiments, the sample is attached to different heat sinks to acquire the optical parameters under different junction temperatures of LEDs. By measuring the junction temperature in the aging process (), and the junction temperature in the testing process (), we achieve consistency with an online test of and and a difference with an offline test of and . Experimental results show that the degradation rate of the luminous flux rises as increases, which yields a difference of projected life of 8% to 13%. For color shifts over 5000 h of aging, the online test shows a larger variation of the distance from the Planckian locus, about 40% to 50% more than the normal test at an ambient temperature of 25°C.
© 2015 Optical Society of America
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