Here's a question for the noise experts:

I've designed a 4-layer pcb running a 16LF876A at 4MHz to be used in a VERY 
noisy environment.  Fortunately there's no A/D functionality needed but 
there's some timing-critical functions to be upheld (20Hz to 1000Hz CCP 
events).  Every trick that I could find to make the design immune to EMI has 
been included or at least considered.  But one consideration that I don't 
know enough about is the need for a copper pour.  Until now, my 
understanding is that a copper pour can be considered as a "poor man's 
ground plane" on 1 or 2-layer boards.  But if my board already has a ground 
plane, am I going to see any benefit by adding a copper pour on any or every 
other layer, or am I just wasting my time thinking about it?

Rick 


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