Etching agitator

It might be a little bit of overkill, but this etching container agitator sure looks convenient. There’s not much to it technically, a small circuit with an ATtiny45. For those beginning with this stuff, he has written a pretty good tutorial on working with basic microcontrollers. If you are more interested in a tutorial on etching, we did a  guide on how to etch a single sided PCB.

22 thoughts on “Etching agitator

  1. An aquarium/air pump is an easy way to agitate etch solution. I used an airstone to get really fine bubbles, but the etch solution dissolved them every few months. Now I just use a bare plastic tube, it does the job but tends to jump around.

  2. Cool, but over design,a simple DC motor and a shaped cam will do the same thing, for $2 in plug and play parts. I too am guilty of forgetting simple mechanical mechanisms that have existed for years for a reason.

  3. I agree with alan. Especially since in my opinion quieter is better. I’d rather not hear the grating sound of a servo while I’m working on something else, or waiting for the etch to finish.

  4. When I etch copper for printing, I use the aquarium pump method in a vertical tank. I suspend the plates so there is no touching of the sides. The pump is connected to a plastic tube with a bunch of tiny holes poked through it with a hot needle. It’s the best method I’ve ever used.

  5. I’ve said it before, but certain etchants (persulphates I think) Don’t benefit from agitation; this should be remembered.

  6. @ ch

    Persulfates do benefit from agitation, at least that is what I have noticed. I use sodium persulfate. Agitation helps delivering new persulfate to the etching site.

    Agitation is also needed to keep temperature of the etchant near the heater below 50 degrees. Higher then this, the etchant can decompose.

  7. Agreeing with posters above, microcontroller not necessary. Here’s a version I made using a gearmotor from an old photocopier.

    http://reboots.g-cipher.net/agitator.mov

    Every moving part rides on precision ball bearings scavenged from defunct hard drives. The carrier was made for a smaller container; for larger boards I use the dish in the video, which rides on rubber tubing and double-stick tape. It looks precarious but it’s actually very stable.

    Air agitation is probably more effective. I prefer the mechanical method because it minimizes clean-up (just the board and dish) and because the motion is so sexy.

  8. Here’s a high-res pic showing the original container if you have trouble viewing the video. Sorry about the messy bench.

  9. It’s a great agitation method for large boards (PC motherobard size) and panels. I’ve built a similar agitatior, though bigger than the one in the video. The etch is consistant over the entire surface of the board which was never the case with air bubbler systems I have used in the past.

    I also used a servo + micro, it was the cheaper and less time consuming option after checking what was in the junk box. It makes a quite a noise though!

  10. Well, I have an aquarium pump waiting, just haven’t looked for a suitable vertical container yet. Maybe I’ll need to go and buy a few pieces of plexy glass and glue them together with something suitable.

    I used a servo in this agitator because I didn’t have any suitable dc motors lying around.

  11. For the people that use a horizontal agitator like the one presented here. What about splashing? Some setups do not have a cover. Even if the waves are small some splashing can occur. I have a cover for my vertical bubbling tank.

    @ reboots: We probably all have messy benches ;-), when you create something, you always create a mess too.

  12. re. airstone. I found some flexible tubing at an aquarium which does the same job.
    If you are going to do this MAKE SURE that the lid is sealed.. or else you will get fine bubbles of corrosive etchant everywhere.

    Re. DC motors, one source is broken VCRs, the loading motor + a bit of polymorph works fine.

    For temperature control, obtain a surplus car cigarette lighter and remove the nichrome tape from inside, then wind it round a glass or mica former and seal it into a glass test tube.

    Works well, and you can use an old soldering iron’s thermocouple as the sensor.

  13. I use a rumble motor from a defunct PS1 controller fixed to the etching tray with a stout rubber band and powered with a single D-cell. It sets up a standing wave. This works beautifully, better than an aquarium pump in my experience, there is no electronics to go wrong and if the corrosive fluid ruins it (I use ferric chloride), I don’t really care as it cost practically nothing to make.

  14. bartb, I’ve had no problems with splashing in my horizontal setup. I use a shallow tray (80mm or so) with no lid.

    nes, That’s a cleaver idea, i’ll give that a try some time.

    For anyone designing a vertical bubbler tank, take care with the lid. It can’t be air tight(you’re pumping the tank full of air, after all) and it must have a lip around the inside. Like the lid on a teapot.

  15. Yeah, I have been looking to make a simple agitator for my etching. I’m not sure mine will need a microcontroller, however. I could match this with the sponge idea for fast, accurate etches.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s