Organosilicone / epoxy encapsulation material
With LED power and brightness increase, epoxy light, heat aging and other aspects have been difficult to meet the packaging requirements. However, epoxy resins have excellent dielectric, adhesive properties, especially have cheap price and low cost. So over the period of time, researchers did not abandon the use of epoxy resin but took advantage of organosilicone to modify epoxy to develop packaging materials with both the advantages of the two materials.
Considering the heat and shining of LED chip is the main reason to cause the adding of encapsulating material, some manufacturers use materials with silicone in the package sheet adjacent the brush inner, an epoxy resin and the outer lens material selection, PC, PMMA and the like. However, practical application discovery, epoxy, PC, PMMA and aging resistance is not enough, and the inner silicone material exists and poor interfacial compatibility. When silicone-modified epoxy resin for packaging materials used, the material toughness and resistance to high temperature has obviously improved.
Silicone packaging materials
Although a large number of studies have proved modified silicone can improve the performance of epoxy resin material, but the molecular structure of silicone-modified materials contains epoxy, which is adverse to radiation resistance of material and is easy to the yellowing problem. Optical clarity and thermal stability of silicone materials play an important role in the high light and high reliability of LED applications. Silicone materials are rapidly replacing epoxy and other organic materials, providing a wide range of potting materials, lens materials, adhesives, sealants and protective coating products for a variety of LED applications.
Currently silicone sealant on the market can be divided into two types: organosilicone material of high index of refraction and ordinary index of refraction, which includes gels, silicone rubber and silicone. Ordinary refractive index of the silicone is mainly of polydimethylsiloxane while high refractive index is sufficient with phenylmethyl silicone based Dun alkyl cyanide. The products of three international Silicon companies Dow Corning Silicone, Momentive and Shin-Etsu Silicones are mainly high refractive index based packaging materials, which have an absolute dominance in the domestic high-end market.