Heat Dissipation Research And Radiator Design Of High Power COB-LED

In recent years,with the rapid development of semiconductor technology,LED has become the ideal light source for household lighting,auto lamps and outdoor lighting because of its energy saving,environmental protection,small volume,high luminous efficiency and so on.Human beings have entered the fourth generation of green technology light revolution.The high power LED packaged by COB(Chip on board)has attracted much attention due to its high efficiency,high integration and low cost.However,because of the large number of integrated chips in the COB package,the heat accumulation is easy to appear in the process of use,which leads to the high temperature of the chip.It will seriously affect its reliability.So it is necessary to research on the heat dissipation of high power COB-LED.In order to get the thermal resistance of all parts of the high power COB-LED,the T3 Ster semiconductor thermal characteristic tester is used to test the thermal characteristics of the COB-LED.The material parameters of each part are obtained by the relationship between thermal resistance and thermal conductivity.The finite element analysis software ANSYS Workbench is used to make a steady thermal analysis on the high power COB-LED by using the sun flower type and the fin type radiator.The simulation results are compared with the experimental results,which proves that the simulation model is accurate and ANSYS Workbench is suitable for the thermal analysis of high power COB-LED.The transient thermal analysis is carried out by ANSYS Workbench.The reasons for the burning of high power COB-LED without adding external radiator are explained.It indicates that heat dissipation is crucial for improving the reliability of high power COB-LED.The curves of highest temperature distribution of each chip are fitted.The influence of thermal conductivity,thickness,section area and cavity on the highest temperature of COB-LED chips is simulated.The relationship between the four aspects and the highest temperature of the chips is found out.The formation mechanism of the cavity is analyzed.Some suggestions are put forward for theimprovement of the coating process of thermal conductive adhesive.According to the characteristics of high power COB-LED heat diffusion and its structure,a hemispherical radiator with grooves is designed.The radiator is optimized by the orthogonal experiment method from the groove depth,fin number,fin thickness and fin length.The optimized hemispherical radiator can reduce the highest temperature of the COB-LED chips to 63.705?,which greatly improves the reliability of high power COB-LED and its volume is less than the sun flower and the fin type radiator.In summary,the heat dissipation performance of high power COB-LED is studied by thermal characteristics test and finite element simulation.A kind of radiator with high heat dissipation efficiency is designed.The reliability of finite element simulation in high power COB-LED heat dissipation design is verified.The relationship between the coating technology of heat conductive adhesive and the highest temperature of high power COB-LED chips is found.The data obtained from analysis simulation and experiments is capable to guide the reliability design of high power COB-LED.