LED (light emitting diode) has the characteristics of energy saving and environmental protection, long service life, low voltage, short switching time and so on. It is widely used in lighting, display, backlight and many other fields. As a connecting link in the LED industry chain, LED packaging plays an important role in the whole industry chain. Among them, packaging material is one of the key factors affecting the performance and service life of LED. Due to the high requirements of packaging material selection, there are high requirements for its light transmittance. Epoxy resin, silicone, polycarbonate, glass, polymethacrylate and other high transparency materials are the main materials in the market. However, due to their high hardness and inconvenient processing, these materials are basically used for outer lens materials.

Compared with the traditional LED epoxy resin packaging materials with high internal stress, poor heat resistance, aging and other defects, silicone resin for packaging has better high temperature resistance or radiation performance, and the Si-O bond angle is larger, which can make the molecular chain of the material soft. Silicone resin is usually prepared by hydrolysis and polycondensation of organosilane in the presence of solvent. The synthetic raw materials are chlorosilane or aChinaoxysilane. Silicone materials have many advantages, especially in heat resistance, anti yellowing and other aspects. Due to the easy modification of silicone materials, functional groups with high refractive index can be introduced into the side chain to improve the refractive index of packaging materials, improve the luminous efficiency of LED, and improve the application range of products.

Silicone material is a kind of material with high UV resistance, high aging resistance and low stress, which has become an ideal choice for LED packaging materials. The transmittance of silicone is directly proportional to the luminous intensity and efficiency of LED devices. The higher the transmittance is, the higher the luminous intensity and efficiency of LED devices will be. Due to the high refractive index (about 2.2) of Gan chip, the refractive index of general silicone material is only 1.4. Therefore, improving the refractive index of silicone material can reduce the difference between the refractive index of Gan chip and that of Gan chip, reduce the light loss caused by interface reflection and refraction, and enhance the light taking efficiency of LED devices.