A Silicon-Based LED Packaging Substrate With an Island Structure for Phosphor Encapsulation Shaping

This paper proposes an encapsulation shaping method for white light-emitting diode packaging, using a silicon substrate with an island structure and using a simple yttrium aluminum garnet phosphor dispensing process. The technology utilizes the interaction of the interfacial tension between silicon island structure and silicone phosphor material for encapsulation shaping at an appropriate curing temperature. Various encapsulation structures, such as hemispherical and shell-type lenses, are fabricated using different encapsulation doses, which allow specific optical requirements to be fulfilled. The experimental results show that a hemispherical encapsulation lens with a radius of curvature of 0.9 mm is formed, when the diameter of the island structure is 1.8 mm and the dispensing dose is 1.5 mL. When the dispensing doses are 2.5 and 4.0 mL, shell-type lens structures with short and long cylinders, respectively, are fabricated. In terms of optical characteristics of the shell-type structure, there is a large measured variation in chromaticity at different view angles, but for the short encapsulation cylinder the uniformity of the lighting is significantly improved. The simulation result for the luminance profile is in agreement with the experimental results.