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SMD Leadframe, instead of plug

Discussion in 'Electronic Design' started by Klaus Kragelund, Feb 20, 2007.

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  1. Hi

    I have searched for a leadframe that fits into the SMD Pick & Place
    machine and that would angle two PCBs.

    The idea is to not use a plug/socket connectors to angle-connect to
    two PCBs, but to use a leadframe (thin pieces of copper bars) to
    connect the PCBs and to do this in the reflow oven

    The idea is sketched here:

    www.microdesign.dk/tmp/SMD_LeadFrame.pdf

    The two PCBs are in the same panel and the leadframe is mounted and
    soldered in the reflow oven. Then just before assembly in the cabinet,
    the PCBs is cut from the panel and the leadframe along with the PCBs
    are bend to the needed angle. This would remove costly connectors and
    would allow any orientation of the PCBs

    But, I cannot find a manufactor of these parts. Any of you guys tried
    this and know of a supplier?

    Thanks

    Klaus
     
  2. linnix

    linnix Guest

    Do you need to separate the boards?
    If not, why not just solder some wires (holes instead of pads)
    between them.

    I did some boards with 20 mils copper alloys.
    Once in place, they are slightly flexible, but never breaks.
    They would rip pads out, but not holes.
     
  3. Rich Grise

    Rich Grise Guest

    I've seen boards mounted at right angles, but the one was soldered
    to the other. The vertical one had essentially an "edge connector",
    and the base had a pattern; then they'd solder it in place:


    | | <- vertical board
    | |
    | | solder fillet (you'll have to imagine an arrowhead ;-)
    | | /
    __________/____\______
    ______________________ <- horizontal board

    but I have no idea how you'd reflow that - the again, I can't
    imagine getting the FR4 out from under your traces, and how you
    reliably bend them without breaking them, and how you secure it
    in its bent position.

    Good Luck!
    Rich
     
  4. Grumps

    Grumps Guest

    An application for a flexi rigid?
     
  5. Eeyore

    Eeyore Guest

    You've got deep pockets have you ?

    Graham
     
  6. Joerg

    Joerg Guest

    I don't know a supplier but similar leadframes are sometimes used in
    making planar transformers when 4oz copper isn't enough. If you can't
    find them on the open market you could contact a company like this one:
    http://www.nwstamping.com/

    In the end that will probably boil down to amortizing the stamping tools
    over the (large) production run. When we needed leadframes for med
    devices they were always custom made to order.
     
  7. Guest

    I have searched for a leadframe that fits into the SMD Pick & Place

    How about this:

    http://www.flexiblecircuits.co.uk/smi_jump.asp

    The interconnects are also available in 0.5mm pitch, although this
    is a new product and is not yet on the web site.

    John Walliker
    www.walliker.com
     
  8. The idea is to avoid hand soldering and leaded assembly to cut costs

    Regards

    Klaus
     
  9. Great - that looks like 95% of what I was searching for

    Thanks :)
     
  10. Thanks for the link

    I will try to quote this custom solution against the weblink from Mr.
    Walliker

    Regards

    Klaus
     
  11. Joerg

    Joerg Guest

    The tape width for SMT placement would make that tough if you want a
    significant overlap for rigidness. Larger stuff such as common mode
    chokes are often placed by hand even in mass production. Question: How
    will those boards be mounted? Even if you found partial leadframes
    wouldn't vibration and other stress eat away at the solder joints?

    I am facing a similar situation right now, three sections that can be
    stiff and two bends. We are going full flex, Kapton based. Rigid-flex
    combo would get too expensive.
     
  12. Robert Baer

    Robert Baer Guest

    There are a number of flex flat cables that may be viable for this.
    Snoop in the online DigiKey catalog.
     
  13. To me, it looks like 100%. What are the 5% you're missing?

    robert
     
  14. Guest

    The 5% is because I would like to have on that is a single device, so
    there is no plastic on the SMD bridge. Then we may solder a wire onto
    the bridge or even better weld a crimp connection onto this (so we
    avoid any leaded soldering).

    Regards

    Klaus
     
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