Thermal Management Design from Chip to Package for High Power InGaN/Sapphire LED Applications

Device performances were investigated for InGaN/sapphire light-emitting diodes (LEDs) with advanced heat dissipation design from chip to package. By directly contacting a copper heat spreader with sapphire, the maximum junction temperature of the LED chip was reduced from 62.9 degrees C of a conventional LED to 48.3 degrees C at an injection current of 350 mA. Further temperature reduction to 37.3 degrees C could be achieved by packaging the copper-surrounded LED chip on the heat sink coated with a diamond-like layer which acts as the second heat spreader. The reduced junction temperature was attributed to good heat dissipation from both the copper and the diamond-like layer due to their low thermal resistance. The copper heat spreader not only extracts heat efficiently, but also enhances the light extraction of the LED, as the copper was designed with a proper geometry such as cup-shaped profile. The improved LED performance suggests that the proposed thermal management from chip to package is an efficient alternative for high power applications.