Investigation of reliability of EMC and SMC on reflectance for UV LED applications

Conventional packaging materials for light-emitting diodes (LED) are susceptible to UV radiation and high temperature. Therefore, for developing UV LED packages, new materials with better UV and high temperature resistance are required. There are two candidates, namely, epoxy molding compound (EMC) and silicone molding compound (SMC), being considered by the industry. This paper focuses on the change in reflectance of EMC and SMC over time as a measure of reliability. Aging was performed on EMC and SMC culls under high temperature, and combination of UV exposure and high temperature simultaneously. Reflectance of EMC and SMC culls before and after aging were compared. It was concluded that both EMC and SMC degrade under simultaneous UV radiation and high temperature aging, and that SMC is more UV and thermally resistant than EMC based on change in reflectance, surface morphology, and roughness.