Development of UV stable LED encapsulants

Abstract

In recent years, high power white LED devices (LEDs) have been developed and widely used in display, display backlight module and general lightings. UV LED pumped RGB phosphors is one of the methods to generate white light. It shows some advantages, such as: excellent color rendering index (CRI), tolerant to LED variation, etc. However, the high energy of UV or near UV based LED lighting source leads to encapsulated transparent epoxy resin chain scission and forms some chromatic sites. The discolored epoxy materials decreases the light output and accumulates heat inside to speed up material degradation. Moreover, LED display and LED lighting devices also suffer UV irradiation from sunlight in the outdoor applications. In order to avoid the UV-degraded problem of LED encapsulating materials, we developed UV resistant material technology. Our developing strategies included evaluating UV stabilizer, synthesis of silicone modified epoxy or curing agent to enhance the bonding energy of encapsulating material.