Homebrew PCBs

On Thu, 14 Sep 2006 17:57:04 +0200, Hector Garcia  
<hectorogarcia@...> wrote:

>
> Now a question raises up my mind: are there some difference between using
> FeCl versus CuCl?

Yes, differences in etching time and agressiveness, but it all depends on  
the parameters you run both etchants at (concentration, temperature,  
agitation,...).
They are similar in the results they produce. You should however not heat  
CuCl (much) because the HCl will fume/boil at low temperatures (50C  
boiling or so and lotsa fumes even below).

> YD said in his post "... still it seemed to work even better than when
> new...", is that argument giving me an answer?

Probably the answer it gives is the "new" CuCl was stronger than the FeCl.

> In the other side, at the first time i made this mix, before to put the  
> HCL
> on the FeCl, y made a test mixing HCL and H2O2, i got faster etching
> results,

Etching times are greatly depending on concentrations, esp. H2O2  
concentration. I have timed a very small board at 11 or 12 seconds etching  
time years ago when i startet with CuCl and did not understand it well. I  
used WAY too much H2O2. It should not bubble at all or you produce large  
amounts of chlorine gas (bad for all living things, and process engineers,  
as they like to joke).


> but, I still have a kind of romantic feel to that old exhausted
> brown liquid and its blue-or-something colored bottle :-) . Maybe some  
> day,
> I'll finally say goodbye to it.

I have no longing for the "stain in a bottle" to return.
I like the clear CuCl so i can see when a board is finished, i place a  
flourescent light (like for car repair) behind the tank.

The FeCl is probably not hurting, but if it isn't doing any good why  
bother? I mean you could also add food coloring to your etchant - but what  
for?

ST