Tom -

When IPC-2221 was developed, the intent was to give the widest possible
lattitude to the acceptability of conformance test coupons, realizing that
many of us had extensive libraries of perfectly good coupons which had been
developed under MIL-STD-275, IPC-D-275 and others.  This produced the last
sentence of Para. 12.4: "Variations in specified coupon design must meet the
intent of the original design and be representative of the board."

We have just undergone a library update, a result of having gone to a new CAD
package.  The system software predates IPC-2221 and has some minor variances
in the coupons it generates.  Once we determined that these have no bearing on
the actual performance  of  testing (IPC-6012 and/or MIL-PRF-31032), we simply
documented the variances and the rationale for their acceptability and got on
with life.

Interestingly, while working on this task internally and with a number of our
board suppliers, I learned that most of the board suppliers would actually
prefer to generate and place the necessary conformance test and process
control coupons themselves.

Regards - Kelly

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