Controlling thermal uniformity among LED chips assembly packages for high-power solid state lighting

We report on the thermal analysis of high-power LED arrays used for solid state lighting (SSL). Variety of assemblies using high-power LED chips, were considered along with different heat-sink designs. Chip-on-plate (COP) packaging technique was used for all the LED chips attached to variety of heat-sinks. The 3D modeling and simulations were carried out to study the thermal behavior of LED chips. The cause of non-uniform chips temperature was analyzed based on thermal resistance circuit (TRC) model and thermal diffusion equations. Comparative study of our simulation results showed that conventional packages can cause temperature differences up to ~7 °C among the chip-array elements at operating at 1.25 W. The temperature difference was found to be less than 1°C for our enhanced assembly design. These findings are of great importance in designing larger LED array packages where thermal uniformity effects would be much significant for color rendering and lifetime.