The Study Of Reliability Of Power LED In LCD Backlight Module

Light Emitting Diode （referred to as LED） is a solid-state semiconductorlighting device. Because of its unique advantages of high lighting efficiency, longlife-span, solid-state and environmental-friendly, it has become a research focus in thefield of illumination technology in the recent years. However, the junctiontemperature has a great influence on the performance of high power LED. The risenjunction temperature will not only reduce the light efficiency, but also directly affectthe reliability of power LED, even shorten the service life of it. In this paper, takingthe power SMD LED in LCD backlight module as the experimental subject，theresearch has three parts of contents.Firstly in this paper, on the basis of test results of LED optical and electricalproperties, an analysis on the optical and electrical properties influenced by the risencurrent and junction temperature was proposed, found that the large current and highjunction temperature will pose a serious threat to the reliability of LED.In this paper,on the basis of a thorough investigation on the methods of LEDjunction temperature measurement, especially the forward voltage method.， ameasurement system was set up based on high-speed data acquisition card andLabVIEW. With it the paper has mearured the voltage temperature coefficient of LEDin different types and analyzed the law and difference of them. With the mearurementof voltage temperature coefficient has been done, this paper also has done amearurement of LED junction temperature,especially the junction temperature ofLED on the radiator of LCD backlight module. This paper has verified the feasibilityof the application of measurement system to monitor LED the junction temperature inLCD backlight module, and offered a test method of the reliability level of LEDtemperature.In this paper, a long-term aging experiment of SMD LED has been done, and inthe aging process also testing the variation of the light output of the LED. According to the resulting data and the corresponding mathematical model a prediction of the SLED effective life has been done. In this paper, a research of the influence ofintensifying the current stress of aging and application of it to evaluate the reliabilityof LED has been done.