Transient Analysis of Partial Thermal Characteristics of Multistructure Power LEDs

The performance of a high-power light-emitting diode (LED) strongly depends on the effectiveness of thermal management. Electrical, thermal, and optical measurements were combined to analyze the complex thermal structure and interface effects inside the LED package. Thermal network synthesis and 3-D finite element modeling simulations are used to simulate the heat flow path and temperature gradient from junction to environment. The exponential curve is applied to model the radiant flux and thermal resistance as a function of heating power. In addition, the results of peak wavelength obviously indicate the blue-shifted phenomena with driving current due to band filling effect and tend to be saturated when the injection current is higher than 0.5 A. The radiant flux showed the opposite behavior as driving current increases. Results demonstrated that partial thermal characteristics of the chip, die-attached layer, and heat slug can be determined individually in the LED packages.