Design and analysis of heat dissipation of LED back light module

High junction temperature in the LEDs would lead to the reliability problems, such as low quantum efficiency, wavelength shifts, short lifetime, and even catastrophic failure. The effects of various parameters, such as thermal properties of substrates, thermal interface materials (TIM) and heat sinks on the thermal performance of the LED backlight module are investigated experimentally and numerically in this study. These LED backlight modules are evaluated in terms of T_j and thermal resistance experimentally by junction temperature tester and IR Thermal Imager, and numerically by CF design simulation. The related junction temperature (T_j) and thermal resistances (R_j-a) for these LED modules are obtained from experimental measurements and simulation. It is found that R_j-a can be significantly reduced by using the heat sinks for all the cases. The results also indicate that the use of Al or Fe heat sinks with any substrates and TIMs do not show any difference in heat dissipation of the module. However, the use of Al or Flex substrate can lower the thermal resistance (R_j-a) by ~32% compared with that using PCB substrate. Furthermore, the simulation validated by surface temperature data of IR Thermal Imager can predict a similar trend of thermal behaviour of LED modules with different substrates and heat sinks and also provides detailed temperature fields of full-scale LED backlight modules.