Homebrew PCBs

On 10/05/2011 6:21 AM, Jim wrote:
>
> Thanks DJ
> Last week I had a 55 oz jar of transparent emerald green etch. Using
> this etch was SLLLOW. I added scrap copper and started bubbling. It took
> about 10 hours to turn OPAQUE. I continued to bubble for another 24
> hours. Removed the copper and continued bubbling. After 2 days, it was
> still OPAQUE. I added 2 oz HCl ... no change ... 1 oz of 27% H2O2 ... it
> turned emerald green. With the additional HCL, I added more copper and
> started bubbling. It took 8 hours for it to turn OPAQUE. I continued
> bubbling for another 4 hours. I removed the copper and continued
> bubbling and after 6 hours it turned transparent emerald green. I don't
> have an hydrometer. The color is a transparent BRIGHT emerald green no
> trouble seeing through the 5 inch diameter jar of etch ... no hint of
> OLIVE green. Should I add more copper? ... When Adam says you can't see
> through but a few mm, Is that the ready to etch transparent state or the
> spent OPAQUE state?
> Jim KI6MZ
>
> On 5/9/2011 11:46 AM, DJ Delorie wrote:
> > The only way to know how "strong" your CuCl etchant is, is to use a
> > hydrometer. The copper makes the solution more dense, by measuring
> > the density you can determine the copper concentration.
> >
> > See http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/ 
> <http://members.optusnet.com.au/%7Eeseychell/PCB/etching_CuCl/>
> > for all the details.
> >
> > Note: my solution looks like the photo at the top of Adam's page.
> >
> > "Spent" etchant is opaque BROWN. This may look like dark green at first
> > because it's mixed, but see Figure 5 on Adam's page.
> >
>
The bright clear green should be ready-to-etch state. Opaque means it's 
spent state. Here's a great resource on the chemistry behind it with 
really good pictures: 
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html 
<http://members.optusnet.com.au/%7Eeseychell/PCB/etching_CuCl/index.html>

Andrew


[Non-text portions of this message have been removed]