Lifetime Modeling And Reliability Analysis Of LED Luminaires

Semiconductor light-emitting diode(LED) luminaires,as a fourth-generation lighting device, is characterized by small volume, long lifetime and high efficiency. Owing to those properties, its application fields extend greatly. However, there is a huge gap between the working time of LED luminaires and its theoretical life,due to short development history, less experience of product design and effective reliability detection method.The effective way of increasing working time and reliability level of LED luminaires is to analyse main failure mechanism and failure mode. The same type experimental samples were provided by a company and the failure mechanism was unveiled under high stress test. In order to build high accurate life model with short time and provide theory basis of screening test, accelerated life test and finite element simulation was used to explore the LED luminaires reliability indexes under high stress. Therefore, those methods had great scientific significance and economic benefits for the improvement the reliability of the LED luminaires.The main works in this paper can be summarized as following:1. Staring from the working principle of LED luminaires, the test sample internal structure and performance characteristics were introduced. Based on the reliability analysis method, the failure mode and mechanism under high stress was discovered. What’s more, the LED luminaires were divided into three sub-systems to determine the weakness and assess the reliability level of the whole system.2. Based on the failure model analysis method, the exploratory test was carried out to determine the accelerated test stress level. The reasonable experiment scheme and testing system was designed to test the LED encapsulation subsystem and LED luminaires. By aid of constant temperature aging test and accelerated life test, the main environmental factors were found by analyzing the test results.3. Finite element thermal and modal analysis of LED packaging and PCBA subsystem were carried out, respectively. The failure causes and corresponding component of LED luminaires were explored according to the test results. It is obvious that the chips and electrolytic capacitor were the weaknesses of LED encapsulation and Printed Circuit Board Assembly components, respectively.4. Based on a large mounts of experimentally obtained data and Arrhenius function, life models of LED luminaires were built by using mathematical reasoning(least square method and unary linear regression method). The FMECA reliability analysis method was used to unveil primary failure modes of LED luminaires. The main reasons that cause the failure include Chip material defect,Silica gel performance degradation and so on. The improvement measures were proposed aim at dominating vulnerable spot of LED luminaires. Those optimization solutions laid a solid foundation for improving the quality and reliability of LED luminaires.