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Date: | Fri, 20 Oct 95 22:02:40 EST |
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I can think of a few good reasons for having coupons. The
most striking one is that it allows for process/product
checks without destroying a perfectly good board. A
cross-section of a coupon designed to the same parameters of
the circuit board and placed on the panel should closely
reflect what a cross-section of live product would look
like. Another good application is with measuring controlled
impedance. Today's designs make it very difficult to do a
good TDR test. Ideally, a 4" to 6" trace with no treeing or
branching makes for the best test. These are not always
evident on board designs, but a coupon can be designed that
way. I hope this helps.
Regards,
Tom Coyle
Field Services Engineer
HADCO Corporation
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