The Study on Thermal Aging Mechanism of Silicone Materials for LED Encapsulation

Light-Emitting Diode (LED) has been widely used in various fields owing to their outstanding properties, such as high efficiency, long service life, diverse colors and environmental friendliness. With the rapid development of LED, the requirements of materials for LED encapsulation are getting higher and higher. Currently, silicone resins are widely used for LED encapsulation because of their unique performance. However, in the process of application, silicone resins suffer from aging due to the thermal produced by LED. In this paper, through analyzing the characteristics in aging based on a failure case, the aging mechanism of silicone materials for LED encapsulation is studied. After thermal aging, silicone packaging materials become hard and brittle, leading to the cracking. Furthermore, the proportion of silicon near the crack increases obviously. In the FT-IR spectra, there is an obvious carbonyl absorption peak near 1720cm
^-1
. In TGA, silicone packaging materials degrade in advance, and the residual mass increase eventually. In DSC, there is an obvious endothermic peak during the first heating process. The fundamental causes of above characteristics can be attributed to the degradation of main chain and the oxidation of side chain.