Homebrew PCBs

Gustavo Villada wrote:
>  
>
> http://www.instructables.com/id/Professional-Home-Brew-PCB-Creating-a-solder-mask/?ALLSTEPS
> the secret is the UV paint.
>

Make sure you read the comments on that instructables.  The guy who 
wrote the instructions advocates drying the paint first, in short, he's 
doing it wrong.

Also, cellophane bags are good for the plastic covering (at least true 
cellophane).  Some plastics are no good as the ink bonds to them just as 
well as to the board. 

Spread ink thinly, too thick and it doesn't cure to the bottom.

Exposure time is long (25-30 minutes), although a short exposure during 
your initial experimentinng will be strong enough to see how it went but 
easier to clean off and re-use your test piece.

After cleaning off the pads, give the board another healthy dose of UV 
to really be sure that it's cooked to perfection.