Printed Circuit Design & Fab - March 2008 - (Page 29)

OPTICAL INTERCONNECT latchability is required, similar to the latchable MPO or MPX style connector housings that are commercially available. A conceptual schematic for this housing is shown in FIGURE 10. Balancing daughter board insertion forces with latching of electronic and optical connections requiring a zero air gap are a challenge, and important step in achieving low loss connections with multiple insertion capability. Capitalizing on the bend flex capability inherent with some waveguide films enables the required flex as the daughter board is inserted. In addition, the bending capability has opened opportunities for through-hinge connectivity for cell phones and lap top computers. Alternative techniques using a lensto-lens coupling at the daughter board-to-backplane optical interface allows an air gap for more forgiving positioning. In Type Five, waveguide film edge ferrule couplings are used with self-supporting links and/or stand alone functional devices. Arrays of single or multi-layer waveguides are precisely centered or positioned within the ferrule. FIGURE 11 shows several MT ferrule connected flex jumpers and board edge substrate links that are fully inspected and ready for installation. The critical connectivity issues for this type include alignment, precision, and coupling issues as previously described. A backplane/motherboard array that is 40 cm long interconnects with high-density waveguide arrays that have been created to interconnect two daughter boards. The 47 cm waveguide optical path (7 cm included for the daughter board) used multiple connections while still operating within the loss budget of 15 dB. The flex circuit shown previously has the substrate attached for the demo board in FIGURE 12. Summary Optoelectronic substrate connectivity is sufficiently advanced, practical and available for consideration in near term applications. For many in the industry, the evolution of optical interconnectivity at the substrate level is sufficient to begin initial prototyping. Technologies continue to develop and improve, opening up new application opportunities. We believe that the approaches outlined in this article suggest that the creation of self-supporting polymer waveguide structures are both achievable and cost effective for many applications. PCD&F ACKNOWLEDGEMENTS The authors appreciate the useful additions, suggestions and comments from Davis Hartman of General Dynamics, Dale Murray of W.L. Gore, Diana Williams of Rogers Corporation, and Silvio Bertling of Parkelectrochemical that have been incorporated in this article. In addition, the extensive help in editing and organizing from Kevin Hair of Optical InterLinks was most appreciated. DR. BRUCE BOOTH is president, founder and CTO of Optical Interlinks. He can be reached at blbooth@opticalinterlinks. com. JACK FISHER is a consultant at Interconnect Technology Analysis. He can be reached at fish5er@mindspring.com. B P O SE EX RIN OT E U PO TE H 1 S 3A LA D C 26 T S IR IP VE CU C G IT AS IMAGECURE® EVER INCREASING RANGE OF COLOURS Imagecure and ImagecureSMART (SolderMask Advanced Resin Technology) are: Halogen free Available in Screen, Spray or Curtain Coat formulations Identical process conditions to green formulation of Imagecure® or ImagecureSMART® Excellent resistance to all final finishes including lead free solder Fast exposing systems giving better depth of cure to achieve finer lines Primary colours are compatible and can be mixed to create secondary colours RoHs compliant Sun Chemical Circuits Norton Hill Midsomer Norton Bath BA3 4RT United Kingdom Tel: +44 (0) 1761 414 471 Fax: +44 (0) 1761 416 609 www.sunchemicalcircuits.com MARCH 2008 PRINTED CIRCUIT DESIGN & FAB 29 http://www.sunchemicalcircuits.com http://www.sunchemicalcircuits.com

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - March 2008

Printed Circuit Design & Fab - March 2008 Contents Our Line Market Watch Around the World Happenings ROI EMC for the Real World Positive Plating FPGA/PCB Co-design Increases Fabrication Yields Optoelectronics Comes of Age, Part 2 Implementation of Buried Capacitance in High-Speed Designs Ad Index Improved Innerlayer Bonding for Sequential Lamination Off the Shelf Marketplace BGA Bulletin

Printed Circuit Design & Fab - March 2008

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