Research On Reliability Of LED Lighting Products

The photonics industry is one of the most competitive high-tech fields in the world, and it will become a significant symbol of economy development of a country. The development of LED, Lighting Emitting Diode, has attracted worldwide attention. With the improvement of LED’s performance, the application fields extend continuously. And it will be expected to become the fourth-generation light source which replaced incandescent, fluorescent and high intensity gas discharge lamps. The LED light source will become the preferred way of lighting in the coming future.However, LED lighting encounters some bottlenecks in its development process. Such as low light efficiency, high prices, short lifetime. And there are misunderstanding in LED reliability judgment because lacking of credible criteria as well as certification bodies. Most manufacturers only pursued the initial performance. For the sake of low prices, they didn’t attached importance to the quality and reliability of LED products.Based on the above reasons, I mainly focus on the research work as follows:Firstly, I introduced the light-emitting principle of LED and the main parameters. And then I described the main advantage of LED lighting products, such as environmental friendly, safety, long lifetime and energy conservation. There were also some problems faced by LED lighting products including cooling, reliability and price.Secondly, I introduced the basic concepts of reliability including reliability rate, failure rate, bathtub curve. Through some reliability problem cases, I emphasized the importance of LED reliability studies. I analyzed the potential failure mode of the various parts of LED products, and described the testing standards and testing methods of LED products in terms of reliability.Thirdly, I got the activation energy value of product A by the accelerated life test with temperature stress. By taking the advantage of Arrhenius acceleration model, I predicted the effective lifetime of product A which provide reference for other similar products. And then I listed the reason of lumen decay for LED products.Fourthly, I described the thermal shock test and the failure mode of LED products in the test. And I introduced a new lead-free solder called Innolot and its advantage. Through the thermal shock test for product S, I studied the influence on solder fatigue which caused by different materials and different Thermal Expansion Coefficient.Fifthly, I introduced Highly Accelerated Life Test and its application with detailed description of HALT test procedure and test method. Through HALT test for Product T, I found that an electrolytic capacitor on the driver is the weak link of the product design. And then I analyzed the factors affecting the lifetime of electrolytic capacitors. Finally, the improvement measure was proposed.