The heat dissipation conditions of high-power 5 watt LEDs-based searchlight modules were optimized with varying LED bar’shape, materials, and ambient temperature. The LED junction temperature was estimated by using Computational Fluid Dynamics simulation. The optimal heat dissipation conditions were found as follows; LED bar’ shape: L=80 mm, W=4 mm, t=10 mm, copper material, LED junction temperature of 116.6℃, ambient temperature of 50℃, total mass of 184 g, and shadowing area of 320 mm2. The difference between the junction temperatures of our fabricated and simulated LEDs-based searchlight modules is about 3℃, which confirms the validity of our thermal simulation results.

Because of the development of LED technology, products due to high output and compact, thematerial with high thermal conductivity has been developed. Now that heat radiating part of the LEDlamp is currently used for die casting of aluminum. The development of aluminum with excellent thermalconductivity is required. In this study, we measured the thermal properties and compared them while weproduced the alloy by changing the component of die casting aluminum. From this study, the thermalconductivity and thermal resistance of the developed alloy were superior to die casting aluminum.

In this study, the heat transfer capability have been improved by using via-holes in FR4 PCB, when the LED lighting is designed to solve the thermal problem. The thermal resistance and junction temperature were measured by changing the dimension of FR4 PCB and size of via hole. As a result, when the dimension was increased initially, the thermal resistance and junction temperature was decreased rapidly, the ones was stabilized after the dimension of 200 [mm2]. Also, the light output was improved up to maximum 17% by formation of via-hole and expansion of dimension in FR4 PCB. Therefore, the thermal resistance and junction temperature could be improved by expansion of PCB dimension and configuration of via-hole ability.

The temperature of junction in LED affects the life time and performance. however, the measurement of junction temperature in module is very difficult. In this paper, to measure the junction temperature in LED module, optical and electrical properties is measured in single package in temperature from 25 [℃] to 85 [℃], and then junction temperature can is estimated in module with measuring the average voltage of single package. As results, the junction temperature of single package is measured the temperature of 61.2 [℃] in ambient temperature, also, the junction temperature of LED module is measured the temperature of 72.5 [℃] in ambient temperature.