Reliability Analysis of High-Power LED Assemblies of Street Light under Thermal Environments  
Author Yao Hsu
Co-Author(s) Wen-Fang Wu; Cheng-Hua Wang
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. In the first part of study, the junction temperature of a single package component under a canonical thermal environment is found through finite element analysis without considering uncertainties of the environmental factors. The lifetime of the package component is estimated after the junction temperature is obtained. In the second part of study, the design of a local street light is considered and illustrated as an example. The circuit configuration of the assembly is addressed and discussed from the viewpoint of a system and its components. To reflect real situation, the uncertainty of thermal environments is considered by assuming the mixed convection heat transfer coefficient is a random variable. It is found that the more of the 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.
Keywords High-power light emitting diodes (HPLEDs), Street light, Thermal environments, Uncertainty, Reliability.
    Article #:  23-167
Proceedings of the 23rd ISSAT International Conference on Reliability and Quality in Design
August 3-5, 2017 - Chicago, Illinois, U.S.A.