Research And Reliability Evaluation Of COB-LED Junction Temperature Based On Different Factors

LED has developed into a new generation of green lighting source,among which,COB-LED is favored by everyone because of its advantages such as high power and high integration.For a highly integrated LED products,high junction temperature and how to assess the reliability problems restricting its development,the current for high power LED chip junction temperature of exploration,design and research,mainly concentrated in the chip radiator and the actual work,junction temperature of LED products usually work by the environmental temperature,humidity,the input current of load,the structure of the chip itself,and many other factors.Therefore,it is of great significance to study the changing trend of influence of different factors on LED junction temperature for effectively reducing the junction temperature of LED chips.Therefore,this paper will conduct simulation and experimental research on the change of junction temperature of COB-LED under the influence of different factors,and conduct reliability evaluation on LED sample chip under the combined double stress load of temperature and current.This paper,by means of finite element simulation,studied the COB and LED lightemitting chip number the sealed and luminescence chip spacing both the influence of different factors on the COB-LED junction temperature,in order to ensure the accuracy of simulation results,the design COB-LED junction temperature measurement sample room temperature environment,and through the contrast with simulation data,and3.302? to verify the simulation of the established model has very high accuracy,and ensure the reliability of the finite element simulation.By optimizing the chip arrangement,the junction temperature of the COB-LED sample was reduced by 1.62%compared with that before optimization,which showed that the optimization effect was obvious and conducive to prolong the service life of LED.This paper adopts the method of experiments combined with simulation,explores the COB-LED products-two working environment temperature and input current load,the influence of different factors on its junction temperature tube pin junction temperature measurement method,measure the different environmental temperature and electric current of load under the COB-LED junction temperature value,compared with simulation data,the error is within 5%,confirms the simulation results are reliable.Results showed that the COB-LED chip junction temperature increase with the increase of input current,and the growth of the junction temperature basic consistent,junction temperature increased with the increase of ambient temperature increase,and adding the value of the numerical value is equal to the ambient temperature increase basic,namely ? Tj = ? Ta,high-power chip change with environment temperature on the junction temperature rise is greater than the small power chip,high junction temperature rise faster.This paper,a temperature and current double stress accelerated life test was designed.Through analyzing the color temperature change track of the sample,it was found that one of the main factors for COB-LED product failure was the decline of the luminescence efficiency of the encapsulated phosphor.Then according to the experimental data,the model of Irene derived temperature-current double stress accelerated life model,predict the product's life under normal circumstances,the reliability of the new assessment of COB-LED samples,and successfully predict the type of LED chips in the normal condition when life is 49658.55 hours,differ with manufacturer to provide test report 50000 hours life 341.45 hours.To sum up,this paper explored the influence of different factors on the junction temperature of COB-LED through the method of combining simulation and experiment,and proposed an optimization scheme to effectively reduce the junction temperature.The accelerated life test of COB-LED is of great significance for the rapid life prediction of other LED products by analyzing the failure causes of samples,predicting the normal life of LED and effectively evaluating its reliability.