Technetters, let me ask a question that has puzzled me for longer than I would like to admit.

6012 requires measurement of internal annular ring on multilayer boards, via coupons taken from opposite corners and in mutually perpendicular directions. This approach makes sense in checking registration of internal signal planes.

What does one do for reference (power and ground) planes, where connections, when required, are to the sheet of copper? Registration for the power connections is not a problem for such a plane. What about registration of signal vias or ground-plane vias, with respect to a power plane? I've looked at IPC-2221 and don't get a clear picture of how to design a coupon for registration check in the latter case.

Thanks for any help. I know designers follow this forum and may have solutions.

Louis Hart
Compunetics
Monroeville, PA
USA
[log in to unmask]<mailto:[log in to unmask]>
412-858-1232


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