We have studied the relation between light extraction from light-emitting diodes (LEDs) and the characteristics and shape of resin by using ray tracing simulations. Light extraction efficiency (ηext) was calculated for various resins of with different refraction indexes, transmittances and radii of curvature of the air-resin interface of a fixed LED package. The models of the LED packages included the packaging substrate, reflector, resin, and LED chip, which consisted of an InGaN chip on a patterned sapphire substrate (PSS). It was found that light extraction from LED packages is enhanced by optimization of the extraction paths of the rays by changing the resin characteristics or curvatures.
2009 The Illuminating Engineering Institute of Japan