Development of Electro-optical Pcbs with Polymer Waveguides

We have developed technologies to embedded high-speed polymer optical interconnects on printed circuit boards for 850 nm applications. In this paper, we show results of fabricating optical-PCBs on a production scale panels in a modern HDI-PCB (high-density interconnect-PCB) process environment. Impacts on board design and manufacturing were studied with the developed optical technology verifiers. One verifier is an opticalPCB with 3-D optical routings realized with embedded waveguides, integrated i/o couplers and optical vias. Another one is a system level optical board assembly with 12.5 Gb/s Tx/Rx devices on surface mounted ball grid array (BGA) modules implemented for optical link analysis. Results show that optical waveguides were successfully embedded in conventional PCBs. Optical layer sustained undamaged during pressing used for multilayer PCB fabrication. Process was found capable of producing versatile multimode waveguides 25-50 μm microns square with step index structures with low-loss and tight bending radius. This paper describes design and fabrication of OE-PCB boards and waveguide termination by out-of-plane optical coupling structures. Fabricated boards are characterized of their functionality, physical characteristics and optical alignment throughout the critical optical path. Based on the results, capabilities of a modern production infrastructure to fabricate optical-PCBs and board assemblies are discussed.