Homebrew PCBs

On Thu, 11 Jan 2007 16:27:23 +0100, Roland Harriston <rolohar@...>  
wrote:

>
> And speaking of outgassing and corrosion: Consider the
> approximately 1 liter of sulphuric acid that almost everyone
> has sitting in the garage most of the time. I'm referring to
> the acid in your car battery, and car battery acid is much
> stronger (Baume) than domestic Muriatic acid.  And besides
> some car batteries are vented!
> To date, I have not noticed any of my tools, electronic
> test equipment, photolab stuff being attacked by the
> gaseous products from batteries in the two cars
> residing in my garage, nor have I seen any ill-effects
> on the automobiles, paint, wiring, trim,etc.


You make the assumption here that the two acids would be similar.

Sulphuric acid does not evaporate and form fumes in the same way as  
hydrochloric acid.

I don't pretend to understand all those complicated things like vapor  
pressure, but maybe someone else is qualified to elaborate.
Look at the boiling points though, over 300C for sulphuric acid and  
something like 50 or 60C for HCl. That'll tell you something about how  
well is evaporating at room temperature.

I can confirm from first hand experience, not assumption, that HCl will  
cause stuff to rust, if left open, in a significant area. Even a closed  
plastic bottle made a spray can rust which was inches away.

ST