Effect of Cross-Linking Density of Silicone Encapsulant on Sulfur Compound Gas Permeability of Light-Emitting Diode

To study the effect of cross-linking density of silicone encapsulant on gas permeability, a light-emitting diode (LED) package was produced with two kinds of silicone, methyl-group (silicone A) and phenyl-group (silicone B), and a sulfur compound gas permeability test of the fabricated packages was performed. We found that the main penetration route of sulfur compound gas into the Ag-plated layer in an LED package could be directly observed by inserting Ag wire in an encapsulant. The persistency rate of radiant flux increased as the curing time of the silicone encapsulant became longer. When electron beam is irradiated on an LED package, the persistency of radiant flux is also increased.