Homebrew PCBs

On Tue, 11 Apr 2006 23:53:49 +0200, Ronald Vanschoren  
<yahoogroups@...> wrote:

> Would I use a test patter or just expose the whole board? How do I see
>
> what the correct time is then? Will it be as clear as copper on one part
>
> (not exposed long enough) no copper on the other (exposed long enough)?
>


no test pattern is needed, although you might put a transparency on the  
exposure unit to add in the attenuation.

You will see after developing clearly the areas that are blank copper,  
which is exposed enough, and areas that will not develop well, some resist  
will be left, those are not exposed enough. The time is selected so it is  
surely long enough to achieve full exposure, but not unnecessarily  
overexpose.

ST