I have a 4 layer design which includes significant areas of solid
     plane on every layer.  Our design guidelines call for clearances
     between the plane and any other conductor (trace or pad) of 0.015" on
     outer layers and 0.012" on inner layers.  Clearance trace-trace,
     trace-pad, and pad-pad is 0.008".  The design Engineer wants 0.008"
     clearance between planes and oher conductive features.  Can anyone
     explain the  reason for the difference between clearance to planes and
     to other features?  We're using 1 oz. copper on the inner layers and
     0.5oz. (1.5oz finninshd) on the outers.  Thanks in advance for any
     words of wisdom you can provide.

     Paul Ziarek

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