On 03 Sep 2013 15:32:43 -0700, you wrote:
>OK, I tried bubbling air through the mixture for about 24 hours with no change.
I wonder about the original proportions, I used about 4 parts H202
(standard drugstore) and 1 part muriatic acid (standard box store).
>I heated to about 40 C and placed a PCB in just to test and after about 25 minutes it had just started to turn pink from etching. The volume was at about 1/2 gallon and to this I added about 1/2 cup of HCL and left the board in for another 30 minutes with little change.
you need to have the oxygen supplied as the solution heats.
I apply the oxygen (bubbler) and allow it to heat. That generally
(with my heater, etc) takes about half an hour to 45 minutes (rough
guess, it may be ready earlier).
∗then∗ I put in the boards. Etching a board takes about 20 minutes to
25 minutes for the first one (not sure what is lacking), and as the
time goes on, I put in boards and overlap them. I've got a population
of boards going through at about 10 minute intervals in completion,
but no idea of how long an individual board takes.
I suspect that within half an hour, the first board would be done, but
I've never bothered to time them. The temperature locally is up to 30
degrees (C) and as such, the bath heats with the air temperature and
the sun. The bubbling air tends to cool off the solution, and I'll
admit that I do not monitor the temperature all that much... perhaps I
will later on..
>
> I think I will now put a lot of copper wire in, at 40 C and let it run to see if it will "take off", as you put it.
it may be a problem with not enough oxygen, which I'd think needs to
have the solution both oxygenated and heated at the same time. Not
obvious from your description that you are.
Harvey
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>--- In homebrew_pcbs@yahoogroups.com, <madyn@...> wrote:
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> On Sat, 17 Aug 2013 00:24:49 -0000, you wrote:
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>>I have a question about CuCl etchant. I mixed up a galon of the stuff using the standard off the pharmacy shelf H2O2 and HCl I normally use in my swimming pool. It worked great in my etchant tank the first time, but I have been unable to get it working again. I've added more H2O2 and HCl but to no avail. The liquid is a nice transparent lime green. Any suggestions on how to recharge the stuff?
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>When first you mix it, it's transparent. The peroxide provides lots
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>of oxygen. After anything from a few days to a few weeks, the
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>peroxide stops providing oxygen to the etchant. (which etchant will
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>turn green as it etches).
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>bubble air through it to provide oxygen and it should take off again.
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>I heat mine to about 105 degrees F to about 110 F.
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>Harvey
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>>--- In Homebrew_PCBs@yahoogroups.com , Philip Pemberton <ygroups@...> wrote:
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>>>
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>>> Right then, time for a quick update...
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>>>
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>>> My CuCl etching bath seems to be well on its way. As of last night, it
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>>> was dark green in colour with white foam and looked like it had oxidised
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>>> as much as it was going to. I added the last few bits of copper wire
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>>> (which were left over from the startup attempt) and turned the air
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>>> bubbler back on.
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>>>
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>>> This evening I found the liquid in the tank was completely opaque -
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>>> white with a hint of green. Almost like someone had dumped a bag of
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>>> plaster mix in there... Oh dear. This one isn't in the manual...
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>>>
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>>> I don't have a hydrometer, so I can't check the specific gravity of the
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>>> solution. For bonus points, I'm still trying to track down some suitable
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>>> containers to do the titration test Adam Seychell describes on his webpage.
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>>>
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>>> ... However the photos of the "you've added far too much NaOH" titration
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>>> looked oddly like the contents of my HCl+CuCl tank... which got me
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>>> wondering -- was the tank low on acid?
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>>>
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>>> Turns out it was. I added a bit of acid (by the highly unscientific
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>>> "just add some with the bubbler on until it's not cloudy any more"
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>>> method) and the cloudiness vanished, leaving the green-black liquid I
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>>> had before.
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>>>
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>>> It's now back on the air bubbler (and foaming like crazy), though given
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>>> the colour of the solution I think it may have already oxidised as it's
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>>> going to (although it went a heck of a lot brighter when I last threw in
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>>> some peroxide, though I'm all out of that at the moment).
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>>>
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>>> --
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>>> Phil.
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>>> ygroups@...
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>>> http://www.philpem.me.uk/
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>>>
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>>