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Conductive pen technique and substrate

Discussion in 'Electronic Design' started by Ken Marsh, Jan 30, 2012.

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  1. Ken Marsh

    Ken Marsh Guest

    Our lab will be evaluating fractal-like antenna. For the initial
    (simple) designs, we are considering to use conductive ink pens,
    primary to save artwork/fabrication time and cost.

    Does anyone have firsthand experience with these, ie. the best pen
    brands, and what type of substrate material to use so the tracks stay

    Ken Marsh
  2. Ecnerwal

    Ecnerwal Guest

    What Phil said. "conductive" ink is often a poor conductor, and very
    expensive compared to either copper tape or attacking a bare copper
    board with an Xacto knife (or paint and ferric chloride - if you can
    paint the pattern you want, you can paint it on copper with a paint
    marker or a brush and etch the copper you don't want off, and have a
    real conductor.)

    I do have firsthand experience, and I hate the stuff.
  3. : Well,if he were to go that route, the silver filled conductive epoxy
    : would be the choice. Mill tiny groves in G-10 plates (milling is cheap)
    : and fill them with it. Makes for precise uniformity of trace dimensions.

    : You can get grooves down to 0.035 easy. Some will do 0.015 for you.
    : Those are mils.

    Do you really mean 0.9um and 0.4um (metric)? We do have a milling machine
    (FEI Helios) that can do it, but I would not call this easy, or a subtitute
    for an xacto knife. Filling the grooves with epoxy would be even more
    difficult. A typo maybe?

    One would need a squeegee of some sort to remove the extra
    epoxy even if you meant 35 mils i.e. 0.035 inch grooves - sounds a bit

  4. Ken Marsh

    Ken Marsh Guest

    Yes, it might be fine for straight lines, but we are wanting to do
    tight curves, zig zags, crosses, etc. That could be tricky with tape.

    Won't bend uniformly. Have to solder cross-overs, etc.

    If anyone ever came up with a laser printer cartridge that deposited
    (real) conductive ink on flexible plastic sheet, they would make a

  5. Ecnerwal

    Ecnerwal Guest

    Conductive particles have a problem with working in an electrostatic process - the fact that the toner is non-conductive plastic is not irrelevant to the process working. Some fairly crude efforts in inkjet have been made, as I recall. Perhaps they have even got a bit less crude - here's one.


    But any of these are likely to provide a result that is not going to behave the same way that copper on FR4 (or flex if that's what you are prototyping for) will. So they may be of limited value as prototypes, anyway.
    Tim left out (though I find it horribly crude - it's quick) Print out the pattern you want in reverse, and iron it onto a board, then etch (soaking the paper off first.) Laser printer toner is actually decent resist (though pinholes are an issue.)

    You could also probably have your local screen-printing place zap out a quick screen of your design and print that onto boards for etching.

    In the "old tech you'd be lucky to find working" line, one of our labs used to plot resist pen directly on copper-clad with a flatbed pen plotter. The rise of the pesky roll and inkjet plotters makes that harder to manage now. Optimists would then think that a conductive ink pen in such a plotter would solve all your issues - good luck with that if you head there.

    Or the old way - printout a laserprinter transparency and expose a photo-resist board, develop, then etch - but that's work, and more importantly in many places these days, a bunch of moderately nasty chemicals. One reason quick-turn board houses get so much business - in any regulated work environment, setting up to be compliant for handling and disposing of and having all the chemistry on hand costs the company more than letting the quickturn house deal with all that. The good ones really are quick, too.

    You're not going to get terribly precise geometry hand-painting the things, that's for sure. And the "conductivity" needs the quotation marks, and costs the earth with all that silver that's mostly not touching all that other silver, so it mostly doesn't conduct much.

    Press-n-peel blue. Stick it in a laser printer, print, then iron onto
    copperclad board. Etch.

  7. Jasen Betts

    Jasen Betts Guest

    the tricky bit would be getting the conductive particles to stick to
    the charged drum (conductive particles won't stick to a charged surface)
    and then they need to fuse at about 100C

    Perhaps indium microspheres coated with some sort of flux-wax, but I think the
    particles need to be magnetic too, lace them with iron fibres ...

    perhaps toner loaded with carbon nanotubes instead, the particles
    still need to be non-conductive until fused.

    You might have more luck with a foil printer, buy you'd need to use a
    metal less reactive than aluminium so it can be plated up to a
    reasonable thickness after printing.

    as I understand it foil printers work the same as thermal transfer
    faxes. the back of a "web" is heated and a fusible adhesive binds it
    to the paper, I don't know if you can put a foil cartridge in an
    ordinary thermal printer.
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