Preparation And Performance Of Organic Silicone Materials For LED Encapsulation

The research and development of organic silicone materials with excellentmechanical properties and bonding performance, which were used for light emittingdiode (LED) encapsulation, have gained the interest of researchers. In this dissertation,the effects of major components of addition-type curable (ATC) liquid silicone rubberand the addition of mono-vinyl POSS on the mechanical properties of ATC liquidsilicone rubbers were fully investigated. In addition, combining the advantages ofepoxy resins and organic silicone materials, novel organic silicone LED encapsulationmaterials with high refractive index and high adhesion were synthesized, and theirapplication in LED encapsulation was also investigated. The main results aresummarized as follows:1. Through formula design, the influence of the type of vinyl silicone oil (linearvinyl silicone oil and branched vinyl silicone oil), the vinyl content of vinyl siliconeoil, the type of cross-linking agent (hydrosilicone oils containing side groups ofhydrogen, hydrosilicone oils containing end groups of hydrogen andhydrogen-containing MQ silicone resins), the hydrogen content and the added contentof cross-linking agents on the mechanical properties of ATC liquid silicone rubberwere systematically researched.2.1,3,5,7,9,11,13-Heptaphenyl phenyl-15-vinyl cage half siloxane (Phenyl-Vinyl-POSS) was synthesized via the corner capping reaction of incompletelycondensed silsesquioxane,[(C6H5)7Si7O9(OH)3], and trichlorovinylsilane. Phenyl-Vinyl-POSS/ATC silicone rubber organic-inorganic hybrid materials were preparedby hydrosilylation between Phenyl-Vinyl-POSS and ATC liquid silicone rubber. Theresults indicate that both mechanical properties and thermal properties of Phenyl-Vinyl-POSS/ATC silicone rubber hybrid materials have been improved compared toneat silicone rubber.3. Under the catalysis of an anion exchange resin, the phenyl-polysiloxane resincontaining epoxy groups has been successfully synthesized by a sol-gel condensationprocess of2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and diphenylsilanediol.Then the epoxy resin modified by organic silicone encapsulation materials have alsobeen fabricated by the curing reaction of methylhexahydrophthalic anhydride and the synthesized polysiloxane resin. The prepared encapsulation materials had goodadhesive property to LED lead frames. Meanwhile, this encapsulation material has asufficient shore A hardness (75A-85A), higher refractive index (1.529-1.545),excellent optical transparency (90%,450nm) and good thermostability. The rigidityand brittleness of epoxy resin could be improved by the introduction of organic siliconchain segments, which results in the decrease of the glass transition temperature (Tg)of epoxy resin.4. Under the catalysis of an anion exchange resin, phenyl-vinyl-polysiloxaneresin containing epoxy groups has been successfully synthesized by a sol-gelcondensation process of methacryloxy propyl trimethoxyl silane, γ-(2,3-epoxypropoxy)propytrimethoxysilane and diphenylsilanediol. Then the ATCresin-type encapsulation materials have also been prepared by hydrosilylation ofmethylphenyl hydrogen-containing silicone resin and the synthesized polysiloxaneresin. The prepared encapsulation materials exhibited a sufficient shore D hardness(32D-38D), good adhesive property, higher refractive index (1.543-1.546), excellentoptical transparency (90%,450nm) and good thermostability (the5%weight losstemperature is above350oC). These characteristics showed that these materials couldbe used in LED encapsulation.