Joanne,

Could it be possible that you have plating up to the
edges of the mounting holes on internal layers? When
the boards were tested the edges were not in contact,
however, when hardware is installed and tightened the
screws become a conductor.

You can check your database or artwork to see if you have
sufficient clearance on all layers for nonplated  holes.
If you find a problem area, you will have to clean and
insulate the hole.

Good Luck


Tom Obarski
Harris Corp

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