Homebrew PCBs

Tom - Many thanks, again.

Grant

--- In Homebrew_PCBs@yahoogroups.com, "twb8899" <twb8899@y...> wrote:

> Grant,
> 
> Most screen printing emulsions are negative acting. Expose them using 
> a postive image of your circuit board where opaque black is the 
> copper and clear areas are etched away. The black areas on your film 
> positive will prevent the UV exposure from making the emulsion hard.  
> The areas that didn't get UV light will wash out leaving an open area 
> in the screen for ink to go through during printing. The film 
> positive should also have it's emulsion on the side that contacts the 
> screen emulsion when UV exposing. This is really important if you are 
> doing fine line work.
> 
> Tom