I'm going back 15 years or so, when cupric chloride etching was becoming a
common system. I don't remember anyone replenishing their etchants with
anything other than hydrogen peroxide and hydrochloric acid. These are
cheap chemicals and the waste can be easily converted to copper oxide
(hydroxide) and sent off for reclaimation. A production etch line was 4 ft
wide and ran 4 to 6 ft per minute with 18 x 24" boards spaced 2" apart.
That's a lot of copper going into solution so the etchant had to be
replenished at a high rate. For the hobbist who etches a board once a week,
simply bubbling air through CuCl etchant and adding a bit of HCl is the
easiest method to regenerate the etchant. If you want to run bigger batches
of boards, get a bigger sump of etchant and let it regenerate for a few
days. One of the links on the list suggested using a picnic cooler as an
etch tank - IMHO a good idea.
The addition of any additional salt content, either sodium or calcium, can
be a problem. I'd have to dig way back to get the details, but in general,
its a good policy to avoid adding stuff to a chemical system if it can be
avoided. There are side reactions that can be really bad news - like
hydrogen gas generation that can cause big BOOMS.
----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 20, 2004 4:03 AM
Subject: [Homebrew_PCBs] CuCl pool stuff
> at tha classic CuCl page:
>
> <http://users.rcn.com/rexa/Projects/CuCl_ech.html>
>
> I found
>
>> It should be noted that in commercial high-volume applications
>> regeneration of cupric > chloride by air oxidation is too slow to be
>> completely practical, so faster methodsare used to reverse the reaction,
>> such as direct chlorination, electrolytic action, or > intense oxidation
>> with hydrogen peroxide or sodium hypochlorite.
>
> see, sodium hypochlorite! that's bleach, well, one kinds of bleach.
> I wonder if calcium hypochlorite does the same.
>
>
> ST
>
>
>
>
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