SUBSTRATE FOR LED WITH TOTAL-INTERNAL REFLECTION LAYER SURROUNDING LED

摘要

A packaged LED module includes an LED die mounted on a substrate surface. A first layer of low refractive index material is formed on the substrate surface and surrounds the die. A lens of higher refractive index material is molded over the LED die and the first layer. The interface of the first layer and the lens reflects light by total internal reflection (TIR) according to Snell's law when the LED light impinges at an angle greater than the critical angle. The first layer may be a low refractive index epoxy, silicone or other material. In another embodiment, the layer surrounding the LED die is processed after the lens is formed to create an air/lens interface for TIR. The LED die may include a phosphor layer, which allows much more side light to be reflected at the interface rather than absorbed by the substrate surface.