Sol-gel synthesized linear oligosiloxane-based hybrid material for a thermally-resistant light emitting diode (LED) encapsulant

A UV transparent and stable fluoro-siloxane hybrid material was prepared for a deep UV-LED encapsulant. The hybrimer was fabricated by hydrosilylation reaction of vinyl-fluoro oligosiloxane resin.

A thermally cured epoxy-siloxane hybrid material that is curable at low temperature (L-expoxy hybrimer) was investigated for use as an LED encapsulant. This new hybrimer was fabricated using thermally initiated, cationic polymerization of cycloaliphatic epoxy oligosiloxane (CAEO) resin, derived from non-hydrolytic sol-gel, mixed with oxetane hardener in the presence of a hexafluoroantimonate-type thermo-cationic initiator. The L-epoxy hybrimer was cured at a lower temperature (below 120 C) than previously reported for an epoxy hybrimer with anhydride hardener (above 180 C). The L-epoxy hybrimer showed high thermal resistance to yellowing under long-term high temperature condition, and maintained good optical transmittance. Also, it had a high refractive index (up to 1.57), as well as the hardness (Shore D 80), and low water-vapor permeability, when the new hybrimer was used to encapsulate an LED, it showed good adhesion without cracks or delamination and maintained their initial performance after the long-term aging tests (120 and 85 C at 85% humidity).