Development of Electro-optical PCBs with Polymer Waveguides for High-Speed on-Board Optical Interconnects

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 opticalPCBs on a production scale panels in a modern HDIPCB (high-density interconnect-PCB) process environment. Impacts on board design and manufacturing were studied with the developed optical technology verif iers. One verif ier is an optical-PCB 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 opt i ca l wavegu ides were success fu l l y embedded in conventional PCBs. Optical layer sustained undamaged during pressing used for multilayer PCB fabrication. Process was found capab le o f p roduc ing ve r sa t i l e mu l t imode waveguides 25-50 m 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, capabil it ies of a modern production infrastructure to fabricate optical-PCBs and board assemblies are discussed. Ke y w o r d s : O p t i c a l i n t e r c o n n e c t s , o p t i c a l backplanes, optical PCB, optical waveguides, μ Development of Electro-optical PCBs with Polymer Waveguides for High-Speed on-Board Optical Interconnects