Reliability Issues of Mid-Power LEDs

The presence of mid- and high-power LEDs in lighting applications is ordinary and widespread. Appropriate life testing and modelling techniques have a great potential in further optimizing both the efficiency and reliability of LED based light sources. A combined electrical, thermal and optical simulation in a Spice-like environment allows fast and accurate system level modelling of even a whole LED based luminaire, provided that the compact models of necessary circuit elements are already available. The work described in this paper aims to make a step forward in LED multi-domain modelling and incorporate elapsed lifetime dependence into an existing LED model. For this purpose, a set of blue mid-power LEDs of a well-recognised vendor were exposed to a cyclic moisture resistance test and an LM-80-08 based life test combined with the latest LED modelling techniques.