On Thu, 01 Aug 2013 02:19:35 +0100, you wrote:
>On 29/07/13 02:01, kabowers@... wrote:
>> This is often considered the best writeup on the subject.
>> He mentions starting with HCl, Cu, and H2O2, but I've never
>> found a copy where he completed that section
>> He does cover starting with HCl, Cu and air.
>>
>> href="http://techref.massmind.org/techref/pcb/etch/CuCl2.htm"
>
>Ah. Looks like I should expect a ~10 day wait then.
>
>I have managed to get my hands on 200ml of 9% H2O2 ("look, that's all I
>can sell you, the law says so"), though I'm not convinced this will be
>enough to start a 1-litre tank.
>
>A quick scan through one of my old threads (from 2010, yeesh!) suggests
>the mix ratio for 9% H2O2 / 17.5% HCl should be around 2 parts acid to
>one peroxide. That gives me (2x200)+200 = 600ml of etchant, all being well.
>
>I've got a few small boards to start with - I'll probably chuck in some
>(stripped) scrap copper wire I have lying around, then the peroxide,
>then the acid ("add acid to water"), give it an hour and maybe chuck in
>the PCB.
Why bother to go that way when the copper from the boards you would
etch would do the same, and get the boards etched? With a lot of
oxygen available, you'll find that these boards will etch rapidly in
the fresh mixture. As the O2 from the peroxide dies off, the bubbled
air will substitute for that and you're building your CuCL2 etchant.
Around here it's used for reducing the PH of pools, and concrete
cleaning, still available in the big box home stores and pool supply
stores under both uses.
Worked for me.
Harvey
>
>That said, I suspect my heavily used FeCl3 bath is mostly CuCl2 at this
>point. After getting rid of the precipitates a few months ago and adding
>what I'd describe as "way too much" HCl, it turned green with a hint of
>brown to betray its iron content. Very strange stuff and very prone to
>foaming if the air pump is turned up to full...