Study On Heat Dissipation Performance And Reliability Evaluation Of High Power LED Based On COB Package

Light emitting diode(LED)as a new generation of green lighting source,has the advantages of long life,high conversion efficiency,energy saving and environmental protection.Among them,LED encapsulated in COB have the advantages of high power,high integration,and low cost,and are widely used in the current.However,due to the problems of low conversion efficiency,poor heat dissipation performance and how to effectively evaluate the reliability of LED is high-power LED restrict the further development of the LED lighting industry in the current,especially heat dissipation issues and life assessment are urgently needed for LED lighting products solved problem.LED are susceptible to environmental factors during operation,and temperature and current are the key factors that always affect the operation of LED.Therefore,this article will conduct simulation research on the heat dissipation of highpower LED based on COB packaging and explore the reliability of LED under the combined load of temperature and current.This article uses the method of comparing the experimental and simulation results to verify the accuracy of the finite element simulation,provides a theoretical basis for optimizing the heat dissipation performance of COB-LED through simulation,and on this basis,optimizes the structure of the high-power COB-LED radiator.Through the finite element thermal simulation analysis of COB-LED,the temperature distribution inside the LED is studied,and the junction temperature measurement experiment is carried out on the LED.The analysis results show that the difference between the simulated junction temperature and the experimentally measured junction temperature is only 3.959?,It can be seen that the results of the two are very close,which also verifies the accuracy of the built finite element model and the reliability of the simulation.By optimizing the structural parameters of the heat sink,the heat dissipation performance of COB-LED is improved.The simulation results show that the junction temperature of the COB-LED is reduced by 10.58?compared with before optimization.It can be seen that the optimization effect is very obvious.By optimizing the heat sink structure,the junction temperature of the LED chip is reduced,which is beneficial to prolong the service life of the LED.In this paper,three sets of accelerated life tests with temperature-current combined loading at different stress levels are designed.According to the color coordinates of the COB-LED sample measured during the test,the main factors for the failure of the sample are analyzed by analyzing the color coordinates of the sample.The luminous efficiency of the phosphor encapsulated inside the sample is degraded;then the parameter of the generalized logarithmic linear model is estimated,and the accelerated life model of the sample under the temperature-current combined stress load is obtained according to the parameter estimation result,and each LED sample is predicted The service life at normal stress levels evaluated the reliability of the LED samples.The results show that the temperature-current dual-stress accelerated life model derived from the generalized logarithmic linear model can accurately predict the life of the COB-LED,and the life of the COB-LED under normal operating conditions is predicted to be 31559 hours.According to the report provided by the LED manufacturer,the reliability life of this type of LED under normal operating conditions is about 30,000 hours,the difference between the two is only 1559 hours,and the error is 5.2%.It can be seen that it is derived by the generalized logarithmic linear model LED life is relatively accurate.In summary,this paper verifies the accuracy of the built finite element model by measuring the junction temperature experiment,and uses the finite element simulation to optimize the structure of the COB-LED heat sink,which reduces the junction temperature of the chip and helps improve the working reliability of COB-LED.The temperature-current double-stress accelerated life test of high-power COB-LED was conducted,the main reason for the failure of the sample during accelerated aging was analyzed,the normal working life of the COB-LED was predicted,and its reliability was evaluated.The manufacturer and the rapid life evaluation of other types of LED in the future are of great significance.