As the "fourth generation new light source", LED has the characteristics of long theoretical life, high luminous efficiency and low energy consumption. It has gradually entered the field of general lighting, and its market share has increased year by year. The ideal life expectancy of LED is more than 50000 hours, but the actual life is far from it, which seriously affects the large-scale application of LED. The reliability test and life prediction of LED are the key to solve this problem. Reliability test and life test can help LED manufacturers find the design defects of LED products and the reasons affecting their actual life in time, so as to optimize LED products and prolong their actual service life.
The life test is carried out by simulating various service conditions in the laboratory. In order to shorten the test time, the test is carried out by increasing the stress without changing the failure mechanism, which is the accelerated life test. The luminous brightness of LED appears the phenomenon of light intensity or brightness attenuation with long-time operation. The aging degree of the device is related to the size of the external constant current source. It takes a long time to actually measure the service life of LED, so it is necessary to carry out accelerated aging test method.
Generally, there are three methods to calculate the life of LED:
1. Extrapolation method of ordinary condition experiment
2. Temperature accelerated life test method
3. Current accelerated life test method
