Fatigue failure modeling of wire bonds of high power LED packages with a multiphysics simulation method

Today, high-power LED packages have been widely used in many fields by virtue of its high efficiency, long service life and small size etc. A LED package consists of many different components, which are made of different materials being operated under different conditions. As a result, each component has its own pattern of impact on the reliability problem of LED packages, such as chip failure, package failure, and interconnection failure and so on. Among these failures, the fatigue failure of wire bonds those work as the interconnection is a common but severe issue that will cause a catastrophic failure of the LED package. Therefore developing a precise prediction method for the fatigue lifetime of the wire bonds has attracted many attentions of LED manufacturers and researchers. In this paper, the thermal, mechanical stress distributions on a high power LED package driven by different currents were simulated from a thermal-mechanical finite element simulation with the ANSYS Multiphysics module. Then the mean cycles to failure could be estimated based on the semi-empirical fatigue model.