Homebrew PCBs

On Thu, 14 Jul 2005 17:15:59 +0200, Mike Phillips <mikep_95133@...>  
wrote:

> I should have some time today to get copper clad board from Halted.
> Has anyone tried using copper pot and pan paste for cleaning bare
> copper? I wonder how that would work over an abrasive pad?
> I have a gallon of Muratic acid. Not sure of the strength, but I
> bought it years ago from a wholesaler. It is typically used to help
> deoxidize brass when soldering car radiators. I poured some on a
> driveway stain one time. It makes kind of a yellow smoke. I thought I
> remember the guy telling me it was pure Muratic. Can it be used for
> etching?
> Mike


You could measure the strength of the acid but i'm pretty sure it will  
work.
It's surely not "pure" hydrochloric acid, those sales guys always try to  
fool you.
When you remove the cap, do you see smoke? if you just see a tiny hint of  
smoke escaping it is around 32%, well at least in this climate.

To use it for etching you need to get some hydrogen peroxide (H2O2),  
ideally around 30%. (The 3% medical stuff has so much water that you can't  
really regenerate your etchant, because it gets diluted too much, but it  
is ok for one-time use).
Alternatively, you can use a bubbling system and air oxygen instead of the  
H2O2, but settle in for some wait.

Not sure about the pot paste. In the end you need a clean, grease-free  
surface (real clean), how you get there shouldn't matter. Let us know if  
you try.


ST