Hi Phil,
This describes the whole process with cupric chloride:
http://members.optusnet.com.au/eseychell/PCB/etching_CuCl/index.htmlI have been using it for several years. Too much acid leads to undercutting, but the amount of acid is difficult for most DIY'ers to access. Go by specific gravity and color.
John
----- Original Message -----
From: Philip Pemberton
To: Homebrew_PCBs@yahoogroups.com
Sent: Monday, March 19, 2012 4:39 PM
Subject: [Homebrew_PCBs] Rejuvenating ferric chloride etchants (was: Darkening laser printer toner?)
On 19/03/12 08:00, Russell Shaw wrote:
> On 19/03/12 12:18, Leon Heller wrote:
>> If it's dark green, it's probably exhausted.
>
> If it's dark green, it will etch perfectly well using a different chemistry if
> you use bubble agitation, and add a bit of hydrochloric acid from the hardware
> shop every few weeks.
>
> I get full etch in 10-15mins at room temperature like that.
Well, I've just filtered the etchant through a piece of kitchen roll (my
first choice was coffee filter paper -- I didn't have any, so I figured
kitchen roll would work as an alternate).
I ended up with a green liquid, and brown paper...
So I think it's a fair bet there's some kind of copper salt in the
solution, along with a tiny bit of iron (it's got a yellowish tint to it).
I've thrown in 200ml of brick cleaner (10% HCl, ~£10 for five litres
from B&Q) and set the valve on the air pump to full. Right now I have
foamy green etchant... I'm going to leave it for an hour or so and see
what happens when I throw some FR4 board offcuts in (lord knows I have
plenty of those after last night's complete abortion of a PCB etching
attempt).
This should be interesting...
Thanks,
--
Phil.
ygroups@...
http://www.philpem.me.uk/
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