Various types of LED based luminaire have been released in the market attracting considerable interest due to advantages such as compact size, high color quality, high luminaire efficacy, and long lifetime compared to conventional light sources. Although LEDs are attractive for lighting applications due to the aforementioned advantages, the extreme sensitivity of light output and useful lifetime to the LED junction temperature remains a unique technical challenge. To overcome this challenge, innovative passive and active cooling solutions have been developed continuously and thus the appropriate methodologies to assess the reliability of LED-based luminaires are required.
Typical LED-based luminaires consist of LED light engine, cooling device, optical component, and power electronics. Each component has unique degradation mechanisms. In order to assess the reliability of the luminaire a hierarchical reliability model has been proposed.