Thermal Parameter Extraction Method for Light-Emitting Diode (LED) Systems

This paper proposes a thermal parameter extraction method for light-emitting diode (LED) devices and LED systems (LEDs mounted on a heatsink). The proposed method provides a simple tool to find out the essential thermal parameters involved in the LED systems, including thermal resistance of LEDs, thermal capacitance of LEDs and thermal time constant of LEDs. All of these thermal parameters are essential for both reliability research and optimal design of LEDs. The concept and significance of the Tau (thermal time constant) of LEDs are emphasized in this paper. Heat transfer equations are initially used for LED devices and LED systems to predict the rising-up junction temperature and cooling-down junction temperature of the LED device and the LED system. Experiments on several LEDs and heatsinks at different time frames are conducted and the practical measurements confirmed the validity of this method and accuracy of the predicted thermal parameters of LEDs.