Chip on Board Packaging and Thermal Solutions for a 100 W Large Monolithic LED

Thermal challenges are now widely recognized as one of the key barriers to LED's fast penetration to broader market. This paper demonstrates an effective packaging and thermal solution for a commercial realization of a large area monolithic LED of 12 mm2, with high current operation and total input power as high as 100 W. A direct chip on board (COB) die attach method was used to eliminate one level of interface such as existed in an SMD LED on an insulated metal substrate. High thermal conductivity LED submount and copper core board were designed for effective heat spreading without a dielectric in the thermal path. The thermal resistance of the 12 mm2 LED from junction to heat sink, including core board and associated TIM1 and TIM2, is as low as 0.7°C/W. A thermal model was developed using FEA to describe the temperature and thermal resistance at each interface, and is shown to be in agreement with measured data. The LED chipsets described here have been used to power systems such as rear projection TVs...