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August 2000

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Subject:
From:
Steve Underwood <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 10 Aug 2000 18:51:57 -0400
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I'm interested to know how y'all interpret IPC-2221, section 12.4.1
"Specimen A and B (Plated Hole Evaluation)..."
"Spacing between holes shall be representative of the printed board.
Conductors shall be included in between the holes on each signal layer."

I have the interpretation that the spacing between the holes (with the
traces between them) will be determined by the worst case pad to trace
spacing on the design.  So, if there are 6 mil lines and 6 mil spaces on
the internal layers but only 8 mil lines and 8 mil spaces on the outer
layers, I would have to set up the coupon with the 6 mil line and space
throughout the entire coupon stack.  This seems to make the outer layer
of the coupon then NOT match the outer layer of the board and the coupon
may fail where the board may not.

Do you make an extra set of A & B coupons for each different spacing
configuration?

Do you mix the hole to hole and pad to trace spacings on the coupons and
potentially increase the size and/or complexity of the coupon?

Steve Underwood
Engineering Manager
Circuit Center, Inc.
4738 Gateway Circle
Kettering, Ohio 45440
937-435-2131 ext. 127
937-435-7698 fax
[log in to unmask]

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