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Slightly OT?: CuCl PCB heater & bubbler

Discussion in 'Electronic Design' started by Mark Jones, Jan 10, 2005.

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  1. Mark Jones

    Mark Jones Guest

    I was wondering, if one were using a typical aquarium-style heater in
    a cupric-chloride etching tank, could the bubbler be placed underneath
    the heater during operation? (Would the "cool" bubbles cause any
    problem with the "hot" heater?)

    Furthermore, did I read somewhere that PCB's should not be bubbled in
    CuCl etchant?

  2. Nico Coesel

    Nico Coesel Guest

    Etching with CuCl is not something to be done at home. The process
    requires constant balancing of the chemicals. It is a very good
    production process and environmentally friendly (the etchant is
    constantly recycled).

    Aren't you referring to ferric chloride (FeCl)?

    Anyway, I don't think placing the bubbler underneatch the heaters is a
    problem. Depending on the size of you tank you may need quite big
    heaters though. My tank needed 2 300W heaters to get 12 liters (small
    miscalculation) of etchant warm in 20 minutes.
  3. Dmitri

    Dmitri Guest

    Mark Jones wrote:

    I would assume you are talking about FeCl (Radio Shack stuff ;-) )

    The aquarium bubble stone will work for awhile, but is not reliable (at
    least to me). Just make sure you cover the container: the bubbles produce
    VERY nasty mist. You don't want it to get on anything around the tank.

    There is a newsgroup that's more narrowly focuses on PCBs and related
    stuff: sci.electronics.cad We keep its Web interface here:
    You may want to try your question there as well.

    Dmitri Abaimov, RCDD
    Cabling Forum, color codes, pinouts and other useful resources for
    premises cabling users and pros
    Residential Cabling Guide

    Article posted with Newsgroup Archive
    no-spam read and post WWW interface to your favorite newsgroup - - 11511 messages and counting!
  4. Mark Jones

    Mark Jones Guest

    No sir, I'm indeed designing a Cu+++Cl etching tank. I've used ferric
    chloride in the past and while cheap and effective, its messy, slow,
    non-renewable, and a disposal hazard. CuCl has its drawbacks too, but
    it also has several marked advantages like its renewability and
    neturalization characteristics. Perhaps I am a little insane. :)

    Indeed! Anyone here not experience "orange finger" syndrome yet? I'm
    designing this new tank with a sealed cover to avoid this very issue.
    For the bubbler I was thinking of a length of polypropylene tubing
    with many fine holes drilled in it. The exhaust will be further
    filtered to remove the HCl fumes.

    Thank you, I will look into it. :)

    -- "God might not play dice with the universe, but he sure can bowl
    when it's raining!" MCJ 20041222
  5. Mark Jones

    Mark Jones Guest

    No sir. I'm aware of the necessary parameters for CuCl3 etchant. With
    the assistance of a microcontroller, maintaining the etchant should be
    pretty straightforward.

    Oh good, that simplifies things. 12L is a big tank! I'm aiming for a
    board capacity of 12"x9" with intermittent use, so only a fraction of
    that volume should be required.

    I saw a design on the web where someone converted a plastic cooler
    (ice chest) into a CuCl etching tank. (Heaven forbid anyone thinking
    there were party punch in there!) The website is gone, but you can
    still see thumbnails if you google for images called "CuCl etching".

    Mark Jones
  6. xray

    xray Guest

    Yes, that was probably my web page. I copied that stuff from a book
    published in 1983, but I did get permission from the author.

    I have used it to etch with a bubbler. It worked but seemed slower than
    FeCl. I still have all the stuff, but haven't found the reason to use it
    lately. In theory, you can rejuvenate the solution just by bubbling air
    through it (to add O2) but in emails with the author, he says he now
    uses strong hydrogen peroxide. You also need to add HCl and water either

    I got myself a web domain and a place to resurrect my pages, but after
    dumping my old ISP, I have been lazy about putting up pages. I want to
    redo them using CSS but I haven't found a style I like yet. When I get
    it finished, I'll post a message here with CuCl in the subject, and give
    a link.
  7. xray

    xray Guest

    In the one I built, I went to the aquarium supply store and found some
    stuff designed for bubbling. Its some kind of porous plastic tubing
    about .25 in dia. I think it is meant for burying under gravel in a fish
    tank. In the bubbler, I ran several rows of it in parallel about 1 in
    apart. Needs a strong pump to feed it all.

    It seems to survive in the etchant ok.
  8. Mark Jones

    Mark Jones Guest

    Oh cool. From what I've found, it looks like the optimum temperature
    for Cu++Cl2 etchant is 130 degrees F. Were you using a heater? (Could
    an ice chest withstand a heater?)

    H2O2 would be an ideal rejuvinator. That extra oxygen atom would
    really do the trick. It seems like nearly all reactions involving CuCl
    produce H20 - with the addition of H2O2 doesn't the solution end up
    being "watered down?"

    This fall I etched a board outside using FeCl... it took nearly 50
    minutes with no heater. I even put a lamp over it, but it still
    undercut noticably. I used a ziplock baggie so no yellow finger
    syndrome and poured the used etchant back into the bottle. Eventually
    it will have to be disposed of. I've learned that if you neutralize
    FeCl etchant with sodium hydroxide, it produces NaCl and Fe3(OH)2,
    which can be burned (reduced) to rust and hydrogen gas. This is still
    a big hassle, and one reason CuCl is looking so interesting. :)

    Great, thanks. Eventually I'll put my design up on the web also. It's
    gonna take awhile though.

    Oh, and for CSS perhaps you'd like - they have a demo, very handy
    for rapid CSS design.

    Mark Jones

    -- "If necessity is the mother of invention, then is experimentation
    the father?" MCJ 20041116
  9. There wouldn't be much water produced if there was no peroxide. The
    basic action is:

    Cupric chloride CuCl2 + Cu -> 2CuCl Cuprous chloride

    You need other stuff, including HCl, because the basic reaction goes
    slowly and CuCl is poorly soluble in water so the reaction stops. The
    peroxide, and oxygen from the air, help to re-convert the CuCl and HCl
    into CuCl2.
    The etchant is ferric chloride, FeCl3. You don't need to use sodium
    hydroxide to kill it, the carbonate (washing soda) is quite OK and less
    dodgy to handle. You get a disgusting-looking mass of ferrous hydroxide
    Fe(OH)2 and carbonate FeCO3. You don't need to burn it; just heat it up
    well until it's dry.
    No hydrogen; you get salty rust (Fe(OH)3 mixture with Fe3(OH)4) or salty
    ferric oxide if you heat it strongly, and water (steam). (In any case,
    burning is oxidation, not reduction.)
    It's not much of a hassle. You could use excess powdered slaked lime
    instead of the soda, which gives a solid mass without heating, but it
    still looks disgusting. It disintegrates as the calcium chloride
    attracts water from the air and dissolves in it.

    The majority advice seems to be that cupric chloride etching is not
    really suitable for small-scale use, but this year is Y MMV.
  10. Nico Coesel

    Nico Coesel Guest

    You'll need at least a heater and a pump. The best way to use FeCl is
    in a spray etching machine though. Etching times of 5 minutes or less
    are achievable.
    You don't need to dispose FeCl. It can be regenerated with
    Hydrochloric acid (HCl). 10% HCl is available in a lot of stores.
    Don't worry about the extra water, you'll need it to compensate for
    loss of fluid due to evaporation.

    I have been using the same FeCl for about 12 years (or more) now.
  11. I read in that Nico Coesel <>
    How do you get rid of the dissolved copper? If you don't, you may
    actually be using CuCl2 as the etchant without knowing it!
  12. Nico Coesel

    Nico Coesel Guest

    I know, but it is not quite the same. When the solution is
    regenerated, a mix from FeCl and CuCl is doing the etching (if I
    remember correctly from my etching bible).
  13. xray

    xray Guest

    I took a fish tank heater -- adjusted to some hottish temp (I can't
    remember the details) and replanted it in a large test tube with
    chemistry rubber stopper and tight sealing enforced for wires and all
    junctions with some kind of "glue" - might have been silicone. I think I
    sealed it hot to minimize expansion pressure.

    With the tight sealing, I got the whole heater horizontal at the bottom
    of the tank. The cooler container has survived so far - only a few
    attempts really, but I don't see problems from the heat.

    On the rejuvenating -- the original article (none of it my work-I just
    provided what I found interesting) has the details. It is not simple.
    You need to monitor both specific gravity and the acid level, by

    I accumulated enough chemical supplies and kludgy apparatus to get it
    done. It is not simple. I doubt if a dash of this or that each time
    would suffice very long.

    On the FeCl side, the original author of my method offered one of the
    best sounding suggestions I ever heard for disposing of spent FeCl
    solution -- Use it to mix with cement (concrete). Send the resulting
    brick to the dump. Any bad stuff should be tied pretty tightly inside
    this brick. Way better than pouring down the drain or somewhere else.

    All these methods have potential negatives. It was mentioned earlier
    that either solution in a bubbler creates corrosive or staining spray if
    not carefully contained or cleaned. The HCl in in the CuCl will creap
    out and attack nearby metals if not tightly sealed, even just sitting

    I'm no real expert on any of this, but I have tried it.
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