Development of a Life Model for Light Emitting Diodes Stressed by Forward Current

This paper illustrates the development and the experimental validation of a life model for light emitting diodes (LEDs) able to predict the time to failure under different stress conditions associated with the value and time dependence of applied forward current. In the paper, three different life models are derived by exploiting the results of tests under constant forward current. Then, experiments performed by subjecting LEDs to simple load cycles characterized by step-varying forward current are carried out, and the results are employed as a benchmark for the predictions provided by the combined use of the life models derived under constant stress and cumulative damage theory.