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Extreme copper p.c.b.s

Discussion in 'Electronic Design' started by [email protected], Mar 14, 2013.

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  1. Guest

    These guys can make pcbs with selective 30oz. copper on FR4...very
    cool. I possibly could've used this last year on my 500A switch.

    I couldn't find a direct link or any decent equivalent articles on the
    web...load the digital version here, then search on "extreme copper":

    See fig. 2, pg. M6.
  2. Bill Sloman

    Bill Sloman Guest

    I wonder what sort of copper to insulator ratio's they can get in
    printed transformer windings? They might be able to do better than
    round enamelled copper wire for low resistance windings.

  3. They say they can make 200oz (which is over 7mm/0.28" thick)!
    That's a fairly hefty bus bar, and might be challenging to solder.

    No online pricing over a few oz.

    This presentation has more information, including the limits on
    spacing etc.. PWB Presentation 20070222.pdf

    Starting with 1-oz and going to 20oz (28 mils) final they recommend
    0.04" minimum width and spacing minimum 0.029".
  4. Guest

    a bit hard to do both at the same time ;)

    I think the guide I've seem the limit is already
    something like 6/6 for 2oz, 12/12 for 4oz

    40oz would be something like ~100 I guess

  5. Bill Sloman

    Bill Sloman Guest

    Interesting stuff. The article does talk explicitily about plated
    windings for transformers, but the web-site doesn't seem to, though
    I'd imagine it to be an appreciable fraction of their business.

    The point that extra-thick copper is a lot more resistant to thermal
    cycling came as a surprise - presumably it's thick enough to
    accommodate differential expansion by deformation, rather than
  6. Tim Williams

    Tim Williams Guest

    Advanced ( is also offering it. They got a new factory up in MN
    that does it, I think. I've heard of UPE before, too (owned by Methode,
    who make buses the conventional way).

    The aspect ratios are pretty much the same, so don't count on making a 20
    mil copper layer with 5 mil gaps and 5 mil prepreg. You might be able to
    get a 20 mil core between 10-20 mil copper, with 10-20 mil design rules.

    Vias are similarly inflated, AFAIK, which probably means smaller ones are
    filled (or nearly so; probably want to check with them first to make sure
    it doesn't, say, trap electrolyte and corrode later on).

  7. Guest

    I'm not sure. I wonder about the skin effect losses in thick plated
    copper. As another factor, the rectangular cross-section gives a good
    fill factor, but not if the multilayer construction adds too much
    space between windings.

    So, could be pretty interesting, but I'm not sure. Somehow I suspect
    it's too pricey for casual uses.
  8. Guest

    Yes, depending on who "they" is, and what "do" means. :)
  9. Guest

    I don't know. I looked hard last year for bus bars and couldn't find
    any suitable standard products--they seem to have faded away. Lots of
    companies make custom, laminated, multi-conductor buss bars to your
    spec, but I couldn't find a simple, thru-hole part with"-spaced

    I had to pass 1kA peak. Total resistance budget was 2 milliohms, with
    1 milliohm allocated for the switch. Rather than mess around I spec'd
    a 3mm copper bar part, 12.5x30mm, surface-mounted. That served as
    conductor and connector, as posted here in sed. Commanded "closed,"
    the proto measured 450e-6 ohms, terminal-to-terminal.

    Here's what it wound up looking like:

    / washer
    crimp _ /_ /
    wire / _|_\/_|_/ ring terminal
    ______ |__|--|__| /
    ------| |------- |--| ---. copper bus bar, soldered to FR-4
    ..'.'.'| | \ \ \ \|--| \ \| /
    ------|_____|------- |--| ---'______________________. FR-4
    | @ @ @|--|@ @ @ @ @ @ @ @ @ @ @ @ @ @| /
    |[email protected][email protected]_|--|[email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected][email protected]_|_____/ /________
    |x| |__|--|__| |x x x x x x x x x x x x x / /x x x x x|
    | | /| |--| | | x x x x x x x x x x x x / /x x x x x |
    |x|/ |_|--|_| |x_x_x_x_x_x_x_x_x_x_x_x_/ /x_x_x_x_x_x|
    / '--' \ / /
    split nut .
    washer .
  10. Guest

    look at something like this:

    claims hundreds of amps and it is press fit not soldered

  11. Guest

    I was thinking copper sheet etched or laser cut to the shape of the
    needed, might even be possible to place and solder with a more or
    standard smd process

  12. Should work if you give it some compliance, eg. a Belleville washer.
  13. Guest

    That's what ovens are for. It gets to be a pain with RoHS but
  14. Jasen Betts

    Jasen Betts Guest

    ? A 60W Hakko works ok here for through-hole, perhaps the 2oz I
    ordered isn't?
  15. Guest

    One of the boards I'm working on now has four layers of 4oz and two
    2oz. There are a few places that it takes a huge iron but not too
    bad. Of course the devices (e.g SON power FETs) that are really using
    the planes for dissipation are a PITA to remove. It's mostly SMT, so
    normal devices are no problem.
  16. Guest

  17. Guest

    Ugh? Copper is beautiful, especially moving big amps. Not ugh(ly)!
    I reflowed the custom 3x12x30mm bus bar onto the proto with an ordinary Hakko--it was easy. I tinned both surfaces, then warmed up the bar. The heat spread wonderfully well. Copper's magic. I even moved it a few times with the same technique.

    Now had the parts been soldered on the bar, that would've been tricky.
  18. Guest

    High current modules, such as 6 pulse rectifier stacks usually have
    screw terminals.

    I guess that you might save something in the assembly work, by
    connecting the device with a few screws to a PCB, instead of manually
    preparing some wire harnesses and then install these to the device.
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