Woodcut Stamps and Conductive Ink

circuit

Even though it’s been a while since the Rome Maker Faire, we’re still getting some tips from the trenches of Europe’s largest gathering of makers. One of these is a 30-minute experiment from [Luong]. He wondered if it would be possible to create SMD circuit boards by using a 3D printer to fabricate a stamp for conductive ink.

[Luong] told this idea  to a few folks around the faire, and the idea eventually wound up in the laps of the guys from TechLab. the Chieri, Italy hackerspace. They suggested cutting a wooden stamp using a laser cutter and within 30 minutes of the idea’s inception a completed stamp for an Atari Punk Console PCB was in [Luong]‘s hands.

As an experiment, the idea was a tremendous success. As a tool, the stamp didn’t perform as well as hoped; the traces didn’t transfer properly, and there’s no way this wooden laser cut stamp could ever create usable PCBs.

That being said, we’re thinking [Luong] is on the right track here with printed PCBs. One of the holy grails of home fabrication is the creation of printed circuit boards, and even a partial success is too big to ignore.

This idea for CNC-created PCB stamps might work with a different material – linoleum or other rubber stamp material, or even a CNC milled aluminum plate. If you have any ideas on how to use this technique for PCB creation, leave a note in the comments, or better yet, try it out for yourself.

Comments

  1. Khordas says:

    Sound like what you’re looking for is a stencil. Could cut one with a laser cutter, squeegee the conductive ink through it.

  2. Richard says:

    I have experimented with linoleum, until I realized that it off gassed with Chlorine gas, to make stamps for HackerSpace passports. The quality of the stamps, even just experimenting and doing initial tests, was very good. We are, however, not equipped to to handle such toxic materials and so, when we actually discovered the makeup of the linoleum we stopped using it in the laser. Finding a material that is flexible and does not contain dangerous off gasses is a challenge and something that I would like. Another member used the same linoleum in a ShapeOKO CNC mill to make a stamp and there it worked very well.
    The only caution I would have is to know the materials that you are using and absolutely ensure that the process does not create hazardous by-products.

    • Quin says:

      Linoleum tile is how my grandfather taught me wood cutting. His technique was to put a thin tile on the wood block, and cut both.

      I suspect that with a small punch tool, you could create the hole marks. And the larger areas could be done with an xacto or similar blade. The lines wouldn’t be as neat as with a laser cutter, but it would be a good way to integrate another hobby or to pick up a new skill if you didn’t already do small wood cuts and stamps.

    • Whatnot says:

      In the old (not that old though) days they used to use asbestos in the backing of linoleum, so it could be (even) worse.

  3. Joejoedancer says:

    How about using that new flexible 3D printer filament, it would make a better stamp.

  4. Norren says:

    A number of years ago, at an Adaptive Technologies conference, I saw what looked like a Vinyl plotter where the cutting bit was replaced with a ballpoint pen. I have to wonder if you could use that type of pen-tip plotter configuration with conductive ink to create a PCB, the company showcasing it was using it to both emboss and ink on translucent plastic with good precision and consistency.

  5. Okian Warrior says:

    Where can we get conductive paint?

    Conductive paste is available in lots of places, but is there something with less viscosity? Something with the consistency of paint, or less?

    Also, the conductive pastes are expensive. Is there a cheaper alternative?

    • Mike says:

      Look for “Bare conductive”

    • Tony says:

      There’s a few varieties around.

      The stuff Mike mentions is probably what people use to electroplate non-conductive stuff, you spray it on cloth/wood/plastic etc and them plate with silver or something.

      The traditional stuff is silver based, mainly used to repair cracks. It’s rather expensive. You can also get a copper-based version that’s a bit cheaper.

      You also have nickel-based paint used for RF shielding where you want to use a plastic case rather than a metal one.

      One problem with these is they tend to be high resistance (compared to bare copper).

      Some people have had the idea of electroplating the paint with copper, I’m not sure if anyone has ever bothered. It’ll work, one minor hiccup is to meed to connect all the the tracks, any left isolated won’t plate.

  6. hue says:

    Well, if you wanted to use a rubber stamp, there are actually places that make material that’s designed to be put into a laser cutter/engraver and be made into stamps. i’ve never messed with that stuff myself. My one time doing laser-cur rubber stamping was with neoprene, and while it made a great working stamp, good LORD does that stuff reek! It’s like a skunk pooping in a rubber boot! But if you want to check out what I did, you can look here: http://weaselsgonarf.blogspot.com/2012/11/first-try-w-rubber-stamps.html

  7. Randy says:

    Silk Screen it? You could possibly have smd t-shirts (hand wash only of course.)

  8. schlem says:

    Are there conductive plastic filaments, and how hard to make same? For that matter, combining non-conductive and conductive filament into a design could render a usable PCB if the electrical connections were sound and robust. Which leads me to ponder semiconducting plastic filaments and 3D printed processors and other components built layer-by-layer like the silicon variety. Cool Stuff!

  9. Truth says:

    How about a 3 step process:
    1 print conductive ink.
    2 cover conductive ink in powered solder dust, using a stencil
    (make the dust using a ball mill)
    3 apply enough heat to melt the solder

    If there is enough conductive ink on the insulating (non flammable) surface the solder should fill in the gaps, you may even be able to place the SMD’s at the same time as the conductive paths are being made if the process works.

  10. aayotee says:

    Why not 3d print directly on to copper laminate and then etch? You only need one or two layers, providing it’s completely covered, then once etched if ABS is used the etch resist can be removed easily with acetone.

  11. RunnerPack says:

    How about CNCing a mold in machinable wax or polyurethane modeling board and casting the rubber stamp from 2-part silicone (or Sugru/Oogoo)?

    Assuming the problem of making a usable stamp is figured out, how about using it to simply stamp some kind of resist (ink, paint, glue, etc.) on copper-clad and etch as usual?

  12. arachnidster says:

    How about lasercutting a stamp, then using resist as ink? Apply to the PCB, then proceed with the regular home-PCB-etch process.

    Alternately, simply using conductive ink with a rubber stamp could be used to make some really cool wearable or flexible circuits.

  13. Phil says:

    For a better transfer of the ink, you could spray liquid rubber onto the wooden stamp. I think the product I have in mind is called PlastiDip.

  14. While this is cool, I’m maybe missing the point – there’s surely a lot easier and more reliable ways of producing PCBs, no? E.g. modding an inkjet printer to print directly on to board stock and then etching.

    Laser-cutting a vinyl sticker works pretty well for coarse boards.

    laser-engraving on rubber – as others have mentioned, there are lots of places with rubber designed for laser engraving. For example http://www.readyforlaser.com/. I have seen stamp engraving in action and it is damn nice! I’d try and get hold of some proper stamp material before messing around with any homebrew solutions.

  15. Kris Lee says:

    I think that they should sand the stamp, then it would provide more even contact.

    But in general this idea feels sound and would allow easy mass production of cheap circuits on paper (just as an example). SMD components could be fixed with conductive glue.

    Then again why not just use inkjet to create the circuits as this would allow more precision and that would allow more tricks like producing proper size stencils.

    Still, the stamp method would allow easy one time but sequent creation of cheap circuits (take paper, stamp it, glue the components).

    • medix says:

      Sanding would definitely help, however I would add a second step to seal the pores of the wood to keep the ink from soaking in. This should help (at least partially) with the inconsistency of the traces. From the photo, it looks like the the ink is too thin. A thicker ink solution would likely coat the stamp better, but there’s some experimentation involved with getting the right thickness (viscosity?) and application volume.

  16. aayotee says:
  17. minifig404 says:

    Rubber stamps are three-part; there’s the wood base, the flexible but not compressible rubber, and the compressible foam between the wood and the rubber. Some 3D printed structure that compresses evenly would probably boost the quality quite a bit.

  18. Taylorian says:

    I am actually working on a kit I plan to bring to market this next spring, that will allow anyone to make professional level PCB’s. I have kits put together for through hole, single and double sided rigid and single sided flex circuits. Keep your eyes open for an upcoming kickstarter for the EasyFab.

  19. butterfly says:

    Jesus h cripes, what the fuck is wrong with copper clad? People have been home-fabbing PCBs since before the editors were born.

    • arachnidster says:

      Yes, god forbid anyone try to innovate!

      • Butterfly23 says:

        go ahead and innovate, but don’t claim your shitty ‘solution’ is solving a problem which has had a perfectly workable solution longer than you’ve been alive.

        • Quin says:

          isn’t hacking about finding a new way to do something with the tools on hand, instead of going out in search of the tolls you already know will work but that someone else controls?

          And if the article upsets you, there is a perfectly workable solution of “don’t read it.” But you had to go and get innovative and claim your solution of ranting was better. ;-p

        • Greenaum says:

          The guy admits it has a few small problems. If your experiments never fail, you’re probably never going to learn anything!

  20. CyberScann says:

    as an idea for stamped pcb’s . stamp an adhesive the rub on a foil gold or whatever even gum and other candy wrappers that use foil covered paper would work you will have a quick easy solder-able pcb’s in a matter of minutes and spray with a non conductive enamel. imoo better concept then conductive inks. they can move power but making a sturdy connection you will need conductive glue’s and using any chip with tight tolerances is impossible glue does not behave like solder

    • Trui says:

      Gold foil is too thin for any serious current. Typical copper on a PCB is about 35 microns. Typical gold foil is 0.1 – 0.2 microns.

      • rj says:

        Just for reference: a trace made of gold foil 1mm (39mil) wide and 0.1 micron thick is about 2.5ohm/cm, which if I’m doing the math correctly would be good for about somewhere around 10-20mA given no more than 25K rise of the trace at 300 K.

  21. It actually worked!
    You can see the result here http://youtu.be/NH0kzoAms5Y
    And you can read Luong summing up the story here http://luongbui.com/circuit-stamping-a-follow-up/

    Thanks for all your comments, precious tips :)
    The result is a bit different that the initial idea, we wanted to use materials we had at our disposal and techniques we were familiar with.
    We didn’t use SMD this time, but we plan future iterations.

    To reply to some of the comments asking why such an idea came out, if you read both Luong’s posts it’s clear we wanted to have something you can print to people in no time, and with no technology like inkjet printers or sorta.
    Basically an analog way to create a flexible PCB on the fly!

    This is just a first step, we wanted to see if it’s possible.
    Now we need to define a better design process, and this will take more time.

    Mostly it’s been cool to see how an idea could start into a Maker Faire, and be prototyped, iterated, transformed, shared in a matter of less than a couple of days of work.
    This processes, techniques and technologies are what makes personal fabrication such an interesting area to explore.
    I’m so excited about what can be done and what we’ll see next!

  22. admin says:

    It actually works!

    You can see the result here http://youtu.be/NH0kzoAms5Y
    
And you can read Luong summing up the story herehttp://luongbui.com/circuit-stamping-a-follow-up/

    Thanks for all your comments, precious tips :)

    The result is a bit different that the initial idea, we wanted to use materials we had at our disposal and techniques we were familiar with.

    We didn’t use SMD this time, but we plan future iterations.

    To reply to some of the comments asking why such an idea came out, if you read both Luong’s posts it’s clear we wanted to have something you can print to people in no time, and with no technology like inkjet printers or sorta.
Basically an analog way to create a flexible PCB on the fly!

    This is just a first step, we wanted to see if it’s possible.

    Now we need to define a better design process, and this will take more time.

    Mostly it’s been cool to see how an idea could start into a Maker Faire, and be prototyped, iterated, transformed, shared in a matter of less than a couple of days of work.

    This processes, techniques and technologies represents what makes personal fabrication such an interesting area to explore.

    
I’m so excited about what can be done and what we’ll see next!

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