A Rapid Test Method for Evaluating the Lifetime of LED Lighting Products

The attenuation of luminous flux is a key indicator for judging the lifespan of LED lighting products. Energy Star (ES) in the United States defines the end of the lifespan of LED lighting products as the luminous flux maintenance rate dropping below 70%. Energy Star proposed to measure the luminous flux maintenance rate for 6000 hours at 25 ℃± 1 ℃ and infer the lifespan of LED lighting products based on this (the luminous flux maintenance rate for 6000 hours is not less than 91.8%). Compared to the development of LED lighting technology and the speed of product updates, the testing time of 6000 hours (or more) is still too long to meet the requirements of rapid industrial development.

Developing a fast reliability testing method for evaluating the lifespan of LED lighting products has become a crucial issue in the industry. In response to this problem, the State Key Laboratory of Semiconductor Lighting Joint Innovation has developed the Test Method for Accelerated Attenuation of Luminous Flux Output of CSA020 LED Lighting Products after two years of research.

On August 9, 2013, DOE reliability research expert Fan Xuejun provided an in-depth and systematic explanation of the principle of the accelerated attenuation test method for light flux output, the validated test data, and the significance of the standard's publication in this far-reaching research achievement.

Based on the experimental methods of Energy Star, LM-79, LM-80H, and TM-21 in the United States, CSA020 proposes a new accelerated decay test method based on the theoretical foundations of the "e-index model", "Arrhenius acceleration model", and "Poisson distribution": by increasing the ambient temperature during testing (to increase the LED junction temperature), the test time is further shortened. Under testing conditions with a recommended maximum temperature of 55 ℃, data within 2000 hours can be used as a substitute for the 6000 hour data required by the ES method at room temperature. This method not only greatly reduces the traditional 6000 hour testing time to within 2000 hours, but also maintains the quality and accuracy of the ES method. Fan Xuejun stated that the feasibility and rationality of the accelerated attenuation test method used in this standard have not only been theoretically proven, but also verified with actual test data of LED lighting fixtures.

At present, CSA020 has been discussed and solicited opinions from a wide range of enterprises within more than 400 member units of the National Semiconductor Lighting Engineering Research and Development and Industry Alliance. It has been voted by more than 80 formal member units and officially released, gradually promoted and applied in domestic testing institutions. As a rapid testing method for determining the lifespan of LED lighting products, it will better support the implementation of national financial subsidies and will undoubtedly play a huge role in promoting the research and development of LED lighting products and industrial development.