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PCB Etching with Muratic Acid, etc. Does it really work? — Parallax Forums

PCB Etching with Muratic Acid, etc. Does it really work?

Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
edited 2009-07-18 19:29 in General Discussion
Has anyone here done any PCB etching with muriatic acid, etc?
(As shown here: hackaday.com/2008/07/28/how-to-etch-a-single-sided-pcb/)

Questions: Does it work as indicated? How small can the traces be? Close enough surface mount?

OBC

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Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2009-07-15 02:06
    Oldbitcollector - aka stunt man

    I would be curious also... I don't think HCl by itself will work, you need the Hydrogen Peroxide to initially get things going. The reason I say that ... as a kid I hollowed out a few pennies by scuffing the side of a penny and allowing pool acid to eat away at the inside portion of the penny. If it's just HCl, the copper is relatively inert.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • Computer Geek 101Computer Geek 101 Posts: 179
    edited 2009-07-15 02:55
    I use HCL and hydrogen peroxide to make all my boards. You need to be careful with the HCL, but it works well.
  • chaosgkchaosgk Posts: 322
    edited 2009-07-15 13:27
    I agree, I've done pretty fine traces with the HCL/peroxide and it's cheap. He is correct, HCL by itself doesn't do much to the copper and peroxide by itself is useless as well. It has to be a combination of both of them. If you have a large board to do, you can use distilled water to get more coverage without losing much effect on the etching.
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2009-07-15 13:46
    How are you guys disposing of the solution after you've used it?
    Do I need to neutralize it in some way to make it safe for dumping?

    Thanks
    OBC

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  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2009-07-15 15:19
    Oldbitcollector,

    The whole idea from the instructables, was that you just kept re-using the "green" solution. Towards the end there was a suggestion to precipitate the copper out of the solution in addition to adding more HCL and Peroxide.

    I believe that there was even the possibility of applying an electrolysis technique, leaving Copper on one of the electrodes. Not sure what you would use for the initial electrode however... Carbon maybe.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • pwillardpwillard Posts: 321
    edited 2009-07-15 15:46
    1) Do it all the time.
    2) I don't throw it away. (but if I did want to... I'm getting real curious if I could electroplate the copper out of the solution and just dilute the rest with water)
    3) I get much better results with PCB etched this way versus FECL. (Mainly because I can see exactly when the etching has completed.)

    It's very affordable...

    Sample of RS485 board with .4mm to .8mm track widths

    pwillard.com/?p=60

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    There's nothing like a new idea and a warm soldering iron.

    Post Edited (pwillard) : 7/15/2009 3:53:16 PM GMT
  • Computer Geek 101Computer Geek 101 Posts: 179
    edited 2009-07-15 19:42
    I use baking soda to neutralize the acid when I'm done with it.
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2009-07-15 23:33
    Here in indiana where our gravel is basically limestone I just pour it out and wash it down.

    I have had some trouble with a strong HCI solution washing the photoetch off. It works quite well otherwise.
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-16 01:45
    This looks fun - I've got gallons of HCl around here and all the other stuff too - except the "magainze paper" [noparse]:)[/noparse]) well OK, you don't have to know how to spell to pour acid. I'll let you know what happens as I've not tried this before.

    All the acids containers I have are stored in a locked cabinet - the bottom of the cabinet is filled with about 10 big boxes of baking soda.·Yeap, if·a container·comes open,·the·spill isn't a problem - and I have·foaming evidence that somethings happening.

    OBC: If you had to·neutralize the solution, I'd add *it* slowly to a large bucket of water (never water to acid!) and then dump in a few handfulls of baking soda until it didn't foam much, then a bit more water, a dash of baking soda again, more water, then all down the street drain or in the sewer. This is fine as long as the pH has gotten near 7 which is what the baking soda, after all, is doing.· (And if that still bugs anyone, realize that it's an old plumbers trick to pour muratic acid in the commode to clear it out - DON'T do this unless you really know what you're doing!) freaked.gif

    - H

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    Post Edited (CounterRotatingProps) : 7/16/2009 1:56:12 AM GMT
  • pwillardpwillard Posts: 321
    edited 2009-07-16 02:48
    If I decide to chuck my bucket of etchant, do I need to worry?

    The real concern though is... you can neutralize the acid... but can you deal with the copper. In these small quanties... is it not worth worrying about?

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    There's nothing like a new idea and a warm soldering iron.
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-16 16:49
    hey pwillard - why worry?

    You know there's probably enough chromated copper arsenate (CCA) in people's yards from pressure treated wood that everyone using it may qualify for their own personal toxic waste dump. (Just kidding - or am I? Guess it depends on the EPA's definition of toxicity - government definitions are a moving target. [noparse]:)[/noparse]) Soooo ...

    Spread it around the yard - it'll give the bugs something yumming to chew on :-P

    - Howard

    http://www.epa.gov/oppad001/reregistration/cca/

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  • $WMc%$WMc% Posts: 1,884
    edited 2009-07-17 01:41
    Quick question

    Will " chromated copper arsenate " work for chinchbugs ???

    Derzban has become almost imposable to get anymore, And I'm tiered of making my own E.D.B. !


    ___________$WMc%__________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • pwillardpwillard Posts: 321
    edited 2009-07-17 02:01
    Worrying over... what's a little copper gonna do?

    Now if somebody beside MG chemicals can make a tinning solution... I'd be in heaven doing my etching...

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    There's nothing like a new idea and a warm soldering iron.
  • KatyBriKatyBri Posts: 171
    edited 2009-07-17 03:13
    What ratio (weight or volume) do you mix the HCL and hydrogen peroxide?
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-17 03:35
    Generally, I use about 1 part HCL to 2 parts H202. I'm not sure of the concentrations, but this is the general, run-of-the-mill HCL found in pool supplies and the Hydrogen Peroxide found in the pharmacy. I think the H202 is something around 3%... Very diluted, but works fantastic.
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-17 15:56
    $WMc% said...

    Will " chromated copper arsenate " work for chinchbugs ???

    Derzban has become almost imposable to get anymore, And I'm tiered of making my own E.D.B. !
    Probably not, it's not really available for retail, AFAICT. It's ment for pressure treating wood, to stop rot and discourage termites, not as as pesticide. Chinchbugs are a PITA - especially for us in Florida, eh?· There's a pellitized treatment for a· spreader that your local hardware store should have. ACE people usually know better than Lowes or Home Depot - I can't recall at the moment what it's called.

    Sorry, what's "E.D.B." --- Electronic Destroyer of Bugs ?·· (First we had the carnivorous robot that fuels itself by eating flys - next we're gonna have a Prop-based bug zapping 'bot... mini-ping with mini-laser ... seeks out and destroys one bug at a time - LOL [noparse]:)[/noparse]

    OK before we risk hijacking OBC's thread with that, I'm researching why the HCl + H202 work together when HCl alone really doesn't.

    - H

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    Post Edited (CounterRotatingProps) : 7/17/2009 11:35:14 PM GMT
  • $WMc%$WMc% Posts: 1,884
    edited 2009-07-18 00:57
    H2O2~HCL

    I've used Hydrochloric acid for years to clean rust off of antique metal parts (iron), I have found that the HCL reaction stops when all the "rust" is gone. Pull the sample out and its just plain gray metal, with only the rusty stuff removed.

    I plain to run a series of test with different H2O2~HCL solutions to see what works best.
    I'll post My findings here!

    I think anything would better than FECL.


    Be careful with HCL as it will attack silver,lower grade gold and platinum.


    E.D.B. = Ethylene DiBromide, It kills chinchbugs on contact, and anything else it gets on.


    _______________$WMc%_________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-18 04:56
    Errr, WMc, are you sure you're using HCL with your iron? It's late and I haven't had much sleep the last few days, but I'm 99% sure HCL reacts with iron vigorously. I don't know what H202/HCl solution would do for rust. The H202 is an oxidizing agent when etching copper(otherwise, copper is VERY resistant to HCl, while copper oxide is not), but I doubt it does much with rust as rust is just iron oxide - i.e. it's already oxidized.

    I never knew we'd be having a chemistry convo in a microcontroller forum. Good stuff though! [noparse]:D[/noparse]
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2009-07-18 04:59
    Philldapill,

    "I never knew we'd be having a chemistry convo in a microcontroller forum." - lol

    Better watch out or someone might come up with a semiconductor.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-18 06:27
    Ha! Well, in my defense, I DID say chemistry - not magic. Semiconductors don't have any electrons. The have magicrons.
  • $WMc%$WMc% Posts: 1,884
    edited 2009-07-18 17:15
    Philldapill

    sorry for the confusion, I was taking about etching copper. I have found that HCL does not attack copper or iron, but will attack copper oxide or iron oxide. Its the H2O2 that makes the HCL useful for copper etching.

    I haven't seen an exact mixture of the two, What is it?


    ________________$WMc%______________

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    The Truth is out there············································ BoogerWoods, FL. USA
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-18 18:43
    Well, the muratic acid from the hardware store - you know the kind for cleaning concrete and balancing pH for swimming pools - is usually ~ %31.5 HCl.

    The H2O2 is drug store "topical" USP grade, about %3. (Anything over %7 is a tad dangerious, >%30 and you can start your own DIY rocket-fuel factory [noparse]:)[/noparse]

    The mix is about 2 to 1 H2O2 to HCl.

    - H

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  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-18 19:29
    anyone know off hand what the purity of the copper cladding is on most of these boards is? I'm guessing it got to be #1 copper and up.

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