An Epoxy adhesive for attaching the Light emitting diodes (LEDs) and the LED lens is composed of Epoxy resin and hardener. The LED adhesive is essential to stick the light diffusion lens on the substrate for smooth and bright light of the LED. It is required different characteristics with general epoxy adhesives such as low-temperature and fast curing. In this study, Hardener with copolymer-based mercaptan silane and Long chain (octyl) silane synthesized by sol-gel condensation reaction. The thermal properties were investigated by Thermo gravimetric analyzer (TGA). Curing behaviors were evaluated by Differential Scanning Calorimetry (DSC) at dynamic and isothermal conditions.