Reliability estimation of plastic LED package with different types of silicone encapsulant and adhesive

To estimate reliability of plastic LED packages based on different types of silicone encapsulant and adhesive, we designed two plastic LED package models using normal refractive index (NRI) silicone or high refractive index (HRI) silicone as encapsulant with epoxy or silicone as bonding adhesive. And then, thermal acceleration tests were performed during 1,000 hours in three different temperatures and optical characteristics were measured at every 250 hours. Exponential decay of luminous flux of plastic LED package was assumed and extrapolation was used to analyze the time-to-failure (TTF) of plastic LED packages. From TTF data, statistical analysis was performed and the reliability parameters such as acceleration factor (AF) and B10 lifetime at 40°C were estimated according to what types of silicone encapsulant and bonding adhesive were applied in plastic LED packages with 90% confidence.