| Light emitting diode(LED) application was extended to all aspects ofpeople’s daily life with the development of semiconductor technology, andLED had been the fourth-generation lighting source. However, in practicalapplications, the heating value of lighting LED modules(especially highpower products) were very high, reliability assessments had became the keyresearch direction, especially for the white LED, which luminous fluxattenuation was very severe under high temperature.In current, it is very difficult to use traditional life test method for LEDlife test which the life is up to5×104h. Traditional life test will consume alot of time and human and material resources. And the life test standard ofLED illumination module is still very indefinite, the detection methods arealso different. Now life test methods mainly depend on the following twoarticles: first, the life test and reliability evaluate method for traditionalsemiconductor electronic devices; second, the international traditional LEDlife test method. According to the shortcoming of the current life test, theaccelerated life test method based on temperature stress and data processingmethod were proposed and demonstrated in this paper. The method describesthe life distribution by Weibull distribution function, analyses test date byusing the least square method and Arrhenius equation. Weibull distributionfunction was used to describe the life distribution, and the least squaremethod combined with Arrhenius acceleration model was used to gatherstatistics and analyze the test data. The results show that the method weproposed can greatly decrease the time of life testing, make it sure to estimateaccurately the life of lighting LED module at the normal working stress in ashort time by this method.The main topics of this research work have the following aspects:(1) In this paper, we set up a program of accelerated life test for lighting LEDmodule, which based on the relevant rules and the characteristics of LED;If the major premise is that the tests do not destroy the failure mechanism, we select the temperature as the accelerated stress for accelerated life test,which can shortly cut down the test time, and implement the rapiddetection of working time.(2) In the high-temperature-stress experiment, we can get the data ofluminous flux, and calculate the accelerated life using degradationcoefficient extrapolated analytical method; combining the theory ofmathematical statistics, using least square method and a principle of linearregression of experimental data to achieve the fast processing, we cancalculate the respectively working time under the stress, which is40301h(60℃)、39466h(80℃)、40267h(100℃); the use of high-speedthermal stress test data under the realization of LED lighting modules,under normal use conditions, the use of rapid assessment of life;(3) The paper describes accelerated life test of the theory applied to LEDmodules life detection, and overcomed the test for a long time operationof complex faults, so that we can make experiment more scientific nature;and the paper analyse the measurement uncertainty of acceleration lifefrom the experiment, pointing out that the activation energy measurementuncertainty is the major impact, which can produce the error on lifeexpectancy projections. |
PDF Full Text Request