Homebrew PCBs

On 15/05/14 20:15, Peter Johansson rockets4kids@... 
[Homebrew_PCBs] wrote:
>
> Interesting.  What about the liquid stuff?  I have seen an application 
> technique where you put a dollop in the center of your board, cover it 
> with a piece of cellophane, and then squeegee it out to the edges.  I 
> don't even think you need to wait for it to dry, you expose it right 
> through the cellophane.
>

That's the theory.  The practice is it's a complete PITA to work with 
the liquid stuff, very messy, hard to get a good smooth surface without 
bubbles, exposure time varies radically with colour, thickness of 
application etc.

There was discussion on this list recently about air-brushing it on and 
pre-baking to dry it before exposure which would give better results, 
but you need to quite precisely control the temperature (apparently, I 
can't reproduce the results yet, don't have a good enough oven) in order 
to hit a temperature which will dry it, but not kill it's ability to cure.

For very small boards it's not too bad, but anything over 2 or 3cm per 
side, it's just frustration city for me.