Thermally stable conformal encapsulation material for high-power ultraviolet light-emitting diodes

A conformal encapsulation material for use in high-power, thermally stable ultraviolet (UV) light-emitting diodes was successfully developed. For silicone, thermal degradation started at similar to 200 degrees C, and the transmittance was 85.5% at 365 nm. The transmittance decreased by 55% after thermal aging at 250 degrees C for 72 h and it decreased further by 2.5%, even at room temperature, under continuous exposure to UV light at 365 nm for 72 h. By contrast, for the sol-gel material, thermal degradation started at similar to 300 degrees C, and the transmittance was 90% at 365 nm. The transmittance decreased negligibly after thermal aging at 250 degrees C for 72 h and it did not decrease further even at 75 degrees C under continuous exposure to UV light at 365 nm for 72 h. (c) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)