Homebrew PCBs

Yes, check the links section.
The two-eyedropper method is best to check molarity sometimes while you  
start the solution.

You don't need to put in any copper or copper oxyde or something, it's OK  
to start with a slightly strong acid and add H2O2 each time in small  
quantities. The CuCl will build up all by itself from the boards.

When way too strong it is mostly oxygen gas, yes, but it also can get hot.  
HCl boils very low, and you can quickly get loads of HCl fumes. There have  
been some accidents with this etchant industrially, where it elegedly did  
"go through walls" and even killed people when way too strong. This is not  
so dangerous in household quantities, but you should not have a violent  
bubbling and you should always have it inside a second larger container  
that also takes some diluting water in an emergency.
Note that when it is so strong it will also underetch and eat all markers  
easily. I know what i'm talking about, when i started with it i once timed  
this etchant at 11 seconds a board (luckily in tiny size/quantity).

ST


On Wed, 08 Feb 2006 23:12:12 +0100, mycroft2152 <mycroft2152@...>  
wrote:

> Definitely too strong!
>
>
> The Muriatic Acid from the Hardware store was 31% and the Hydrogen
>
> Peroxide from a beayt supplies store was listed at 40 volume.
>
>
> I got the formula proportions from googling. I'll eat my own words,
>
> so much for accurate info when when googling.
>
>
> Fortunately, there was very little chlorine gas. I'm familiar with
>
> the odor, the bubbles were probably oxygen from them excess peroxide.
>
>
> I've already diluted the solution and it has stopped bubblng.
>
>
> A six or seven minute etch from the reference in the files section,
>
> seems a lot more reasonable and controllable. I remember reading the
>
> about acid etching in the fioes section, a while back, before I was
>
> actually interested in trying it. Thanks for the reminder.
>
>
> I'll try it the 'right' way next time.
>
>
> And yes, I had goggles and gloves on while working with it.
>
>
> Myc