The Study of Thermal Resistance Deviation of High-Power LEDs

The high-power light-emitting diode (LED) lighting is especially essential in the high-temperature applications, such as the street lighting and automotive lighting. However, there is more than 70% of electrical power converted into heat due to the low electrical-optical conversion efficiency. Because of the characteristics of the semiconductor, the electrical property of LEDs is sensitively varying with operating temperature. These deviations affect the measurement of light and electricity. In this paper, the steady-state thermal measurement techniques developed by the National Institute of Standards and Technology are used to study the deviation of thermal resistance in different electrical and thermal conditions. The consistent trends of simulations and experiments represent that the design of the heat dissipating path and geometry affects the measurement of thermal resistance.