Homebrew PCBs

> There also seems to be photo-process liquid resist but i do not know how
> they prevent it from filling the holes. You could drill after, but
that is
> not an option for a commercial setup with PTH.
> 


I just thought about this. You mask the areas that you want to remove.
So all the pads are masked off. Then you expose it to UV. Then you
clean it and all the areas that were masked wash away. So all the
stuff in the holes will simply wash away as well. I think that is the
way it would work. 

Trev