Scott,

Internal layer breakout is allowed in Class 2 and Class 1 of IPC-RB-276 and
the superseding document, IPC-6012, but not at the interconnect.  I think
that Class 3 in the specification will retain the no breakout condition for
some time  One of the fears is not just electrical shorts, but potential
shorts where spacing is reduced down to 0.001 inch by breakout.  The
integrity of the interconnection of the completely circumferential annular
ring seems to be less of a problem per the ITRI report.

Phil Hinton

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