Transfer molding of primary LED optics; High aspect ratio domes

Miniaturization of clustered high power LEDs by direct molded optics is an upcoming development. This paper discusses the transfer molding process of high aspect ratio optical domes for high brightness multi-LED packages. The fabrication process is separated in three subjects; First mold-cavity manufacturing techniques are discussed. Secondly the mechanics of the hyper-elastic release foils are characterized and analyzed using finite element analysis. Thirdly, silicone flow behavior is characterized for the optimization of the silicone injection parameters and package design. Finally the results are combined to produce an operational demonstrator containing 45 domes, with a height of 7 mm, molded directly on a single board containing LEDs.