Investigation of thermal properties of power LED illumination assemblies

The reliability and long-term stability of solid-state lighting devices strongly depend on successful thermal management. It is well known that junction temperature instability negatively impacts the lightning properties of LED illuminators. However, for prediction of life time and longterm stability the temperature distribution also inside the color converter must be known. A deeper understanding of these demanding thermal issues is provided in our paper on the base of measurements and simulations also taking into account the spatial power loss distribution due to absorption of light and Stokes shift within the color converter. For this purpose 3-dimensional models were set-up and examined to thermally characterize high-power LED assemblies. Two different types of set-ups were investigated. Moreover, an efficient solution is presented where a junction-to-case thermal resistance below 10 K/W is achieved.