We are having a discussion about putting traces under a mounting screw or
standoff in the INNER layers of a multi-layer board.  The question is mostly
mechanical and concerns drop test breakage of the internal tracks.  I'd like
to find out what others have experienced with the following conditions:

Inner layers (1/2oz copper) have traces under the standoff pads (or pad area
if unsupported), 5x5 design rules.

1)      4 layers, top & bottom pwr planes, 0 inner pwr planes.  Can traces
break during drop test?
        With supported holes -
        With unsupported holes -

2)      8 layers, top & bottom pwr planes, 2 inner pwr planes.  Can traces
break during drop test?
        With supported holes -
        With unsupported holes -

3)      16 layers (or more), top & bottom pwr planes, 4 inner pwr planes.
Can traces break during drop test?
        With supported holes -
        With unsupported holes -

If the design rules were 8x8 or 10x10, would this be any more robust?  Or
would the thickness of the copper be the controlling factor?

Thanks,
Cherie Litson, CID
President, IPC Cascade Chapter
PCB Designer / Librarian, SonoSite, Inc.
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