Analysis of Thermal Performance of High Power Light Emitting Diodes Package

This paper reports on the thermal characteristics of the high power LED package. The increment of input power generates more heat in the chip, decreasing the luminance and life span of LEDs. To enhance the efficiency of high power LEDs, challenges related to thermal management need to be addressed. In this research, a detailed finite element model of the high power LED package with proper input power and boundary condition is established using the ANSYS
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finite element analysis program. The applied input power is 1W on GaN, and the convection coefficient is adopted from William's experimental results. Radiation is also included in the FEM model. Additionally, forward voltage methods used to indirectly measure the junction temperature are also performed to validate the finite element model with predicted input power. The simulation results closely match the experimental data, with only 5% error. Various thermal performances under different design parameters of the high power LED package are developed following verification of the simulation analysis. Five design factors including (a) the substrate of the chip, (b) the thickness of the die attach material (c) the electro-optical conversion efficiency (d) the thickness of the copper slug and (e) the area of the copper slug are chosen to determine themost dominant factor in this study. The factorial design provides a guide line for the compromise between thermal enhanced design and manufacturing process in the future.