Homebrew PCBs

-trim-

> you to search the net on muriatic acid pcb etching to see how 
others have
> done it.
> 
> -Tony

Tony, 
Your ratio is WAY off. There was a recent thread on this and I 
suggest you look over the archives of the past couple (3) weeks.

The basic jist is 15% Muratic (hydrochloric) acid and about 2% H2O2. 
This isn't the acid etching, it's Cupric Chloride. The free oxygen in 
the H2O2 breaks the hydrogen from the hydro-chloric acid, producing 
water and free chlorine. The free chlorine recombines with copper 
from the board and produces copper-chloride. There's more to it, but 
I'm not going to reprint it here. There's a lot of great technical 
details on previous posts and in the links section. Do note though 
that acid from the hardware store is about 30% to start with and 
various H2O2 supplies are different percentages too.

Others reccomend against medical 3% H2O2, saying that it's not strong 
enough. I'm using it successfully. I've a solution of 1 part 32% 
acid, and 2 parts 3% medical H2O2 and it works fine. Stronger H2O2 
can be used to recharge the etchant, but you can also recharge it by 
bubbling air through it. THERE IS NO NEED TO EVER DISPOSE OF ETCHANT 
AGAIN. It can be rejuvinated endlessly. Again, read about it in the 
links section.

-Denny