Lifetime Distribution and Reliability Analysis of High-Power LED Assembly of Street Light Under Thermal Environments

Abstract

High-power light emitting diodes (HPLEDs) have been applied extensively in lighting industry. This study proposes a procedure for analyzing the reliability of a typical HPLED assembly of street light under thermal environments. The junction temperature of a single package component under a canonical thermal environment is found through finite element analysis. The lifetime of the package component is then estimated with the help of the life prediction rule after the junction temperature is obtained. To reflect real situation, the uncertainty of thermal environments is further considered by assuming that the mixed convection heat transfer coefficient is a random variable. To simplify the analysis of the assembly, the circuit configuration of the assembly is addressed and discussed from the viewpoint of a system and its components. It is found that uncertainty of thermal environments does make the lifetime distributions more dispersed. With regard to the reliability, the assembly degrades faster than that of its package components; however, the reliability distribution of assembly is more concentrated than that of its package components. The results of this study can provide information for a street-light engineer to plan a maintenance strategy in advance.