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PCB Etching with Hydrochloric Acid

Discussion in 'PCB Layout, Design and Manufacture' started by blackstone, May 14, 2013.

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  1. blackstone


    May 14, 2013
    Hi Everyone.

    I've normally been using pre-sensitised PCBs that you expose to UV and then put in developer. However I've decided to try and use the Laser printer=>transfer=>etch method using Hydrochloric Acid and Hydrogen Peroxide.

    I have plenty of peroxide, and bought hydrochloric acid today, the smallest amount I could buy was 5L.

    For protection, I wore jeans and a long sleeve shirt, rubber gloves, and safety goggles that have a foam sealing ring around the eyes.

    I opened the bottle of acid, and it started fuming immediately, a thick white mist came out. This was unexpected and I immediately sealed the container.

    Is the acid perhaps too strong or something? The fuming scares me, has anyone else had a similar experience and gone through with the etching process?
  2. shrtrnd


    Jan 15, 2010
    It's not the 5Liter volume that worried me, what's the CONCENTRATION of the
    hydrochloric acid that you bought?
    Check what's recommended for your application, compared to what you bought.
  3. BobK


    Jan 5, 2010
    Well, I have never heard of using HCl for etching. Ferric Chloride is the normal etchant, and is not nearly as nasty.

  4. CocaCola


    Apr 7, 2012
    Even in low concentrations hydrochloric will fume chlorinated gas when exposed to the atmosphere especially if the humidity is high... This is normal, but don't take it as 'safe' you don't want to breath the fumes!

    Don't breath it, do it in a VERY well ventilated area and follow all safety precautions... Cloth clothing offers little protection, BTW... If you are doing this indoors even with ventilation (and even outdoors) I would suggest a respirator (gas mask), chlorine gas is nothing to downplay it will tear up your lungs in no time flat...

    As for using it for PC board etching, I have read about it but never done it before, Ferric Chloride is easy enough to get and works well without corroding everything in the immediate area... BTW, I'm serious a container of hydrochloric acid left open will rust and corrode anything in the immediate area...
  5. eKretz


    Apr 8, 2013
    Yeah I wouldn't mess with HCl anywhere except outdoors or under a serious exhaust hood. Coca-Cola isn't joking about the rusting issue. It will rust any ferrous metal anywhere near the fumes. Muriatic will do the same as it's just another name for HCl.
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Boiling ferric chloride will do a really good job too. I have a colleague that found out the hard way.
  7. DuctDuck


    Jan 26, 2013
    I only have a little understanding of the HCl peroxide etching process...what you are after is CuCl2 to form taking away material from your board.

    You could burn up a precise amount of Cu with HCl for CuCl product. Add that to a volume of water with peroxide and your board: viola!

    Have you read something about CuCl in an etchant tank and a fish aerator? You may omit peroxide. But do your own reading first, and please post again!
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