Fast life-time assessment of LED luminaries

The life-time assessment is becoming one of the major concerns for LED industry. It is highly requested to develop an effective and fast life-time qualification method to support and drive LED industry. In this paper, firstly an overview of the life-time assessment methods for LED products is conducted. A comparison has been made among the methods. Traditional constant stress accelerated test (CSAT) requires long test duration, with complication to select stress level, large sample size, high test cost and so on. The step stress accelerated test (SSAT) method has several advantages, such as suitable for long life field, short test time and few sample size, showing the potential for application to the reliability testing for LED products. Secondly, SSAT study was conducted on LED module and LED products. A design of experiments was performed based our preliminary SSAT results. Then a series of tests have been carried out. The effective accelerated degradation paths demonstrated that a fast life-time qualification procedure could be developed with step stress testing. Based on the test results, a step stress based fast life-time assessment approach is proposed for LED Products.