Cooling performance enhancement of LED (Light Emitting Diode) using nano-pastes for energy conversion application

Abstract

LED (Light Emitting Diode) has been expected as the next generation of lighting system due to its high efficiency. However, the hot spot problem of the LED is very critical for its lifetime and efficiency. TIMs (Thermal Interface Materials) have been used to enhance the cooling performance of the LED. However its thermal conductivity is not high enough to overcome the hot spot problem. In this study, nano-pastes are made by adding CNT (carbon nanotube) and graphene to the thermal grease to enhance the heat dissipation. It is found that the thermal conductivities of CNT grease and graphene grease enhance up to 16% and 6% at 0.75 wt% of the nanoparticles, respectively, compared with the pure thermal grease. The cooling performances of the LED package with applied CNT paste and graphene paste are enhanced by reducing the LED chip temperature 7.5 degrees C and 5.5 degrees C at 0.75 wt% of nanoparticles, respectively. It is also found that the nano-paste materials help the enhancement of heat spreading to remove the hot spot problem. (C) 2014 Elsevier Ltd. All rights reserved.