Etching brass and copper with The Etchinator

If you’re in to making your own PCBs at home, you know the trials of etching copper clad boards. It’s slow, even if you’re gently rocking your etch tank or even using an aquarium pump to agitate your etching solution. [cunning_fellow] over on Instructables has the solution to your etching problems, and can even produce printmaking plates, jewelry, photochemically machine small parts, and make small brass logos of your second favorite website.

The Etchinator is a spray etcher, so instead of submerging a copper clad board into a vat of ferric or cupric chloride, etching solution is sprayed onto the board. We’ve seen this technique before, but previous builds use pumps to spray the etching solution and cost a bundle. [cunning_fellow]‘s Etchinator doesn’t used pumps; it’s driven by two cordless drill motors sucking up etching solution through a hollow tube.

The basic idea behind the build is sticking a vertical PVC pipe in a box with etching solution. Mount an impeller in the bottom of the tube, drill many small holes in the side of the tube, and spin it with a motor up top. The solution is sucked up the tube, sprayed out the sides, and falls back down into the reservoir. Put a masked off copper board in the tank and Bob’s your uncle.

Not only did [cunning_fellow] come up with an awesome PCB etching solution, but the same machine can be used for etching brass plate for printmaking, and even photoetching brass sheets for model planes, trains, and automobiles. The quality is really amazing; the Instructables robot above was etched out of 0.7 mm thick brass, with an etch depth of 0.35 mm with only 0.05 mm of undercut. A very awesome build that is already on our ‘to build’ project list.

Comments

  1. Wow, I was trying to design a spray-etch tank recently (Because I’m sick and goddam tired of bubble etching) and I had been wondering if a piece of PVC pipe with a bunch of tiny holes would be sufficient or if I’d need actual nozzles… This sure answers that question!

    And then it goes a few miles past my wildest dreams by not even having a pump! DC motors? Really? Yeah, i think I can scrounge a couple of THOSE up! ;P

    Awesome build, gonna help me IMMENSELY.

    • pcf11 says:

      Bubbling isn’t working for you? How hot are you running your tank? I’ve had boards etch in under 2 minutes bubbling with a hot tank. If you’re not seeing fumes rising you’re etching too cold.

  2. Munch says:

    Why does everyone say there’s no pump, when I see two? Something has to get the etchant up from the bottom of the reservoir, and that something is a pump, even if it works on a vacuum somehow.

    • Munch says:

      More precisely, the “pumps” are the same kind as used in perfume spray bottles, where high-pressure air is used to draw up perfume through a venturi and out a nozzle. Same idea applies here. But, it’s still a pump.

    • Saying “it doesn’t use a pump” is simpler than saying “it uses a piece of PVC pipe and a DC motor to effect a pumping apparatus, in place of a larger and more expensive commercial solution”, and everyone ELSE got it.

      As someone who often argues for the sake of arguing, I’m not one to talk…but there’s a time and place for being that pedantic.

  3. rus says:

    @Brain,

    Normally, you have the best grammar on the site, and I appreciate that. When you are done being an ass though, the very first definition of “pump” is;

    pump1    [puhmp] Show IPA
    noun
    1.
    an apparatus or machine for raising, driving, exhausting, or compressing fluids or gases by means of a piston, plunger, or set of rotating vanes.

    So, @Munch is right.

    Also, your statement “The Etchinator is a spray etcher, so instead of submerging a copper clad board into a vat of ferric or cupric chloride.” is missing the rest of your thought. Yes you get to it later, but it’s confusing to read. Then there is ” Nearly daily HaD reader I’ve talked to…”, and I have to ask, do you mean “Nearly every HaD reader…”? As a nonnative english speaker, it is very hard to understand what is conveyed when those that are can’t use it properly.

  4. Andrew says:

    It’s a pump.

  5. n0lkk says:

    I was sort of expecting to see a finer spray, why I don’t, when the best you cab expect from pumping water through holes drilled in a pipe is a streams of water. Maybe I’m having one of those days pump I’m not seeing the pump lifts water along with providing enough volume, and pressure to force the fluid out of all the holes to pride even coverage. No matter, I don’t etch enough boards to construct this anyway, and any artistic use really doesn’t interest me. Not to mention I’m fare enough into the boonies that scrounging up some of the materials would be a challenge

  6. snurfel says:

    make small brass logos of your second favorite website
    not!

  7. hospadar says:

    THE SOLUTION to your etching problems!
    oh man, I’m sure that wasn’t intended, but it got me good.

  8. pcf11 says:

    Maybe aquarium bubblers suck? I never tried one. I use a cheap 12V tire inflater pump to bubble etchant. Works great!

  9. technodream says:

    to the workshop-deprived, I would suggest another route – print a peristaltic pump from thingiverse. the throughput is small, but the pressure is high, so you can use a descent nozzle to get a fine mist-like spray.

  10. cunning_fellow says:

    But a fine mist is not what you want.

  11. technodream says:

    actually i took a look at the end of the post where he talks troubleshooting and the biggest problem is non-uniform spraying , which makes some areas etch faster than others. wouldn’t mist give much higher uniformity than the ~0.3″ – spaced streams he is using now?

  12. cunning_fellow says:

    I think the spacing is actually more like 0.08″

    There needs to be enough weight behind the impact to disturb the insoluble film of spent etchant. Maybe if your only going to use amonium persulfate then do a mist. If your using either of the chlorides then is suggest going with volume.

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