Advanced molding technique for optical transceivers

Abstract

With the growing use of fiber optics in Local Area Networks (LANs), efforts to cost reduce the optical components has intensified. In general, optoelectronic components for Fiber Distributed Data Interface (FDDI) and Fiber Channel LANs have been LED-based Optical Data Links (ODLs). Due to the bi-directional nature of most links, the trend has been towards the integration of simplex optical transmitters and receivers into Optical Transceivers. Further cost reductions through the use of automated assembly processes such as two step overmolding have also been reported recently. In this paper, we propose a molding technique designed to further cost reduce optoelectronic devices. The technique involves the use of a one-step overmolding process to encapsulate the electronics and injection molded connector receptacle. The injection molded receptacle is designed to provide support and alignment for the Optical Sub-Assemblies (OSAs) prior to overmolding. With the electronics on its substrate (Leadframe/HIC), the optics on the receptacle, and the link between the optics and the electronics complete (wirebonded), the substrate and the receptacle are overmolded in one step. This technique eliminates the need for the first mold process inherent in the two stage overmolding technique. The one step method also removes the need for precision mold features required for optical port alignment and subsequent final assembly (necessary in the two step method). This method, however, combines five active components into one integrated unit-requiring the use of "Known Good Die" to ensure a trouble free device.