PCB Bath Comes From Russia With Love

[Ruvin Kub] likes magnets, a lot. Most of his projects feature some sort of magnet and his PC board agitation bath is no exception. You can see a video about the device, below. We’ll admit our Russian is pretty rusty, but if you ask YouTube nicely it will translate the Russian subtitles into whatever language you like.

One of the things we liked about the video was that he uses hydrogen peroxide, citric acid, and salt as an etchant. We’ve seen the same mix with vinegar or muriatic acid instead of citric acid. We aren’t sure what the actual  translation is about why he doesn’t like ferric chloride, but YouTube says, “she’s too gloomy for my light souls.”

There are a few translation glitches, but overall the design is straightforward. A motor moves a little see saw in the base with magnets that repel similar magnets in the tank. In that way, the electronics are isolated from the liquid. The whole affair runs on a rechargeable battery.

As a bonus, in the end, there’s a brief tutorial on making a board with toner transfer along with comparing the time to etch the board with agitation and without. Like a Tootsie Roll Pop, he finally got tired of waiting for the non-agitated board and finished it with agitation. The test board that started in the bath had been done for a long time.

If you want to try different etching solutions, we’ve asked people to share their favorites. Or, just break out that CNC machine.

18 thoughts on “PCB Bath Comes From Russia With Love

      1. No wait, I can just make it out, it’s not listening to it, it’s singing it…

        (Death Growl) “We gonna eat the face off some copper, stomp tracks through it’s soul, terminate what’s proper, take our corrosive toll…. “

        1. Brilliant, sounds like a good choice of etchant then..
          Cupric Chloride is what a little lighter? Perhaps a Hard Rock soundtrack? Certainly can’t be from the “Sex, and drugs and Rock ‘n’ Roll” excessive partying crowd, they die rather young and its a very long life etchant.. So its got to be one of the cleaner living Rock bands..

    1. I’m using hydrochloric acid for nice green shades and under a minute etching jobs. Also, ignore all the warnings in video below, he’s using H2O diluted version for the kids with safety gloves. Using only HCl + H2O2 in a closed space gives shitload of pretty bubbles and fumes that will clear your lungs and grow hair on your chest.
      https://youtu.be/mANutb83cBc?t=170

  1. An air bubbler (in cupric chloride, don’t know if it works with any other solution) is more effective than this but there is a problem of making the etching even. Something that rotates the board over a strip of air bubbles is something I’d like to try out.

    1. OMG! Time warp!

      Just for the record, I’m on my second batch of etchant in what, now, 12 years? And I only had to get rid of that first batch because I moved internationally, and didn’t want to bring it on the plane with me…

      I’ve literally got 100+ PCBs worth of copper dissolved in a 1 mL bottle in my bathroom right now.

      It’s not for everyone — you have to toss a capful of acid or peroxide in every once in a while — but it’s a damn good etching solution. (Double entendre.)

    2. About 4 years ago I bought a bottle of 1L of HCl, at 33% concentration, because it was pretty cheap and was preparing to move away from the FeCl2. However, i still had some old solution left and that stuff seems to just work, over and over. So never had a chance to play with the hydrochloric acid and that bottle was left there to rot.

      One year ago I decided to inspect the bottle since the area around it seemed to behave strangely. The bathroom mirrors started getting dark at the edges, glass was getting foggy, bare metal parts were rusting. I had a metal container of paint thinner and it was corroded almost into non-existence. I decided to inspect the HCl, which was double-insulated with HDPE.

      Some little voice in my head told me to put PPE on, and it was right, as the bottle ejected a plume of pressurized HCl once opened. No persons or materials were damaged, but it served as a reminder to not keep dangerous stuff around.

  2. A former electroplating shop laboratory analyst tells me that the mixture used is in the family of solutions called “chloride etches” in the trade.

    HCl, or whatever weak acid you are using, plus copper reacts quite slowly. It will clean surface oxide off straight away but the bright metal will only react fairly slowly.

    Adding hydrogen peroxide oxidises the surface of the copper, which is then very quickly attacked by the weak acid.

    If you don’t have HCl handy, acetic acid, or even citric acid (as in this case), and NaCl will still produce (rather dilute but nevertheless effective) HCl sufficient to do the job.

        1. Etch inside a closed container, like a sandwich box or something. Side benefit: you won’t spill any when you’re agitating either. And if you’re impatient, you can heat it by floating the box in a sink full of warm water.

          No fumes, no mess, no fuss. Shake it as hard as you want.

          Just put it in a tupper.

  3. Nope. HCl will not release sensible chlorine vapours or gases until in concentrations above 35%, heated or electrolized. Chlorine is corrosive but isn’t toxic by itself until it bonds with copper.
    In any case use of safety gloves and glasses is recommended. And remember NOT to use metal tools while dealing with the board.
    As for hydrogen peroxide, it’s a lot effective but it dilutes the solution a lot lowering the chlorine concentration by replacing that with water and increases the amount of the etching solution to store. I’m working in a closed as possible loop without adding any H2O2 solution adding few etching solution and letting the board exposed to the air and to the acid bath until it etches.
    Slow and boring but allows me to recycle as long as possible the etching solution.

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