In recent years there has been a growth in the optronic (optical, photonic and optoelectronic or OE) content of board-level assemblies, particularly for telecom applications. This trend is likely to accelerate and widen to high speed datacom applications. Examples of optical components include passives, such as couplers, isolators and filters, and active components, including laser transmitters, transceivers and optical amplifiers. These components are typically “pig-tailed” with one or more lengths of optical fiber for optical coupling, and electrical socket or solder interconnects for the OE actives. Assembly and test with these components presents several challenges. Optical fiber requires careful handling to avoid entanglement, damage and maintain required bend radii. Fusion splicing of fiber involves a sequence of manual operations, several of which are critical to the quality of the splice. OE components are often expensive and incompatible with solder reflow temperatures because of distortion of the adhesive bonding materials used to maintain the alignment of the optical elements inside the package. Optical testing involves measurement of power output, insertion loss and for modulated signals, parameters such as extinction ratio and bit error rate. The ability to test and diagnose defects in complex optical networks depends on the repeatability of test equipment, component performance and optical connectors, which are prone to contamination. This paper describes the issues facing the board-level assembler, offers some practical solutions and discusses trends in OE component packaging and assembly.
Key words: optoelectronics, assembly, test, fiber optics, splicing.