Techniques Of Predicting Life Of LED

Semiconductor lighting is supported by the state’s emerging industries, in recent years, LED technology has made dramatic improvement in performance, and then the optical efficiency LED lighting has been improved. Further improvement of the LED and the kit is designed to optimize the LED performance, and promote LED lighting market. LED reliability of the research is to improve the reliability of the premise and foundation, this thesis related to the mechanism of LED reliability prediction life prediction part, try a stress condition in both the accelerated life test, to achieve the reliability of LED Quantitative prediction of the new method can save the life test costs for screening and early failure of LED products provide the basis for quality management, research and industry for LED have important academic value and practical value.Based on the derivation of a large number of calculations and laboratory accelerated life testing, the system of the LED’s reliability has been life test and failure analysis results, the greatest impact on device reliability, thermal characteristics were analyzed. Specific studies include:1Accelerated life test:designed the accelerated life tests, combined with the life test model, extrapolated to accelerate under high temperature accelerated life and current methods, and deduced the double-stress accelerated life test, determined the experimental program, drawn life-stress curve. Should be noted that in the current test samples are LED units, and does not include the driver and shell lamps, etc., so the actual application of the outer wall due to the light, drive life and wire bonding the lead with the reliability of Department will make this value than the life of the device low.2LED thermal characteristics of analysis:analyzed the performance of high temperature LED and the resulting loss of principle, that the ambient temperature and operating current is the main cause. According to life-stress curve analysis of the thermal effect on the life of that will accelerate the thermal effect of LED device failure, greatly reduced during the life of, and proposed solutions.3Failure analysis:study design and failure to accelerate test samples, the resulting failure mechanism is as follows:high junction temperature causes the degradation of epoxy packaging material reduces light extraction efficiency; white LED, YAG phosphor degradation occurred at high temperatures; LED active region or limit the level of point defects generated due to defects in growth level; high-density defect caused by metal electro migration causes the device to open or short circuit; p gold electrode weld quality is not high; packaging materials and other materials of different coefficient of thermal expansion caused by cause device failure and other mechanical stress.