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High junction temperature accelerates the degradation of the chips and the package materials of high power light emitting diodes (LEDs). In this paper, two experiments were conducted to investigate the fluctuation of junction temperature in the aging process. At the ambient temperature of 65°C, the samples from four different types of LED packages were used to investigate the variation of junction...
High power light-emitting diodes (LED) are widely applied in many fields for their special advantages compared with other light sources. Many researches on LED reliability have been conducted in order to build the better LED design. However, seldom detailed reasons for the LED performance degradation are illustrated in the previous research when LED modules work under a certain thermal and moisture...
To analyze the effect of moisture on the reliability of LED modules, diffusivity of packaging materials must be provided. Polycarbonate (PC) is an important material for LED lens. Its diffusivity measurement is usually based on the solution of one-dimensional diffusion. In this paper, the diffusivity measurement of PC was conducted. Simulation and analytical close-form solution (CFS) were also used...
As thermal performance is importance for high-power LED devices, there exists a need to build a validated model to clarify the thermal transfer mechanisms in the LED chip in terms of the chip materials and structures. High-power LED was numerically investigated using the finite element method. A series of substrate materials with different thermal conductivity and thicknesses were studied. The impact...
Aiming to study dynamic mechanical properties of the transparent silicone resins for LEDs packaging and the effects of dynamic mechanical properties on the reliability of high power LEDs, dynamic mechanical analysis (DMA) has been adopted to study one silicone resin used for packaging high power white light LEDs. The viscoelastic behavior of silicone resin was obtained from multi-frequencies dynamic...
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