High performance encapsulants for ultra high-brightness LEDs

Abstract

The performance requirements for packaging ultra high-brightness LEDs are extremely demanding. These include high continuous use temperatures and light fluxes. Polymer encapsulants play a critical role in the extraction of light, as a host medium for the phosphors to convert blue to white light, and as capping lenses. Encapsulants must also meet critical requirements for viscosity, modulus, and optical transmission under varying environmental conditions, while having a high refractive index to maximize device efficiency. We describe the development of robust one-pot encapsulants having refractive indices of 1.57 and greater than 1.6. These encapsulants are stable at 200 °C for time periods greater than 4 weeks.