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Subject: Re: Printing pcb patterns negative or positive

From: "Steve" <alienrelics@...>
Date: 2003-12-16

--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
> Steve wrote:
>
> >
> > I'm really confused. Black areas are where copper is.
>
> Exactly.
>
> But black areas
> > over the emulsion result in it washing away.
>
> Again exactly.
>
> This isn't making sense
> > to me.
>
>
> If black areas are where the copper is, but instead you need black
> areas over what to remove, then you need a negative of the copper areas
> image to expose the emulsion.

Well, I was answering Tom and he said:


> 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.

Which doesn't make sense. What -you- said makes sense. Use a negative
image with negative resist.

Steve