With rapid development of lighting emitting diode (LED) market, more people are focusing on reliability testing method of LED luminaries system. However, it is difficult to use traditional reliability testing method for electronic products to assess LED luminaries with high reliability and long life. In this paper, reliability testing methods applied on LED, LED luminaries and other fields are reviewed shortly, and step stress accelerated life test (SSAL T) and step stress accelerated degradation test (SSADT) are selected for exploring reliability testing on commercial available LED systems. According to special characteristic of LED system and advantage of each method, both of methods are combined into one testing plan for evaluating system life. Proposed methods are also conducted on one thermal testing example by focused on commercial available LED bulb and lamp-cup systems. Explored results suggest that step stress accelerated test is an effective accelerated test method for LED luminaries. At the same time, there are still many challenging aspects for system reliability test, such as complicated failure mechanisms, Life gap among subsystems and also product manufacturers and lack of appropriate models to extrapolate. To assess the system reliability in future, an assessment procedure to subsystems is proposed by combining mentioned step stress accelerated test and system statistics analysis methodologies recommended in recent literature.

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This article describes research on changes of glass transition temperature of electron encapsulated polymer-epoxy molding compound (EMC) after thermal oxidation under high-temperature air storage conditions. The evolutions of glass transition temperature of two EMCs with different compositions (different filling contents) under different temperatures (175, 200, and 225 °C) and different aging times (100, 500, and 1500 h) were analyzed by dynamic mechanical analysis (DMA) technology. Research results demonstrated that two glass transition temperatures occurred during thermal aging. These two temperatures were the glass transition temperature of the unaged core material (Tg1) and the glass transition temperature of completely oxidized surface material (Tg2). Tg2 increased continuously with the increase of temperature and the prolonging of the aging time. The filling content could have significantly influenced the aging degree of materials.

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