I will take a shot at this.  The A/B coupons on all IPC-6012/6013
products are supposed to be from the IPC-2221 designs. This coupon is
35.0x14.0 (1.378x0.551 inch) per FIG 12-2 of IPC-2221 and this "little
specimen" is supposed to represent the quality of its associated board.
Per Fig 12-1, this coupon is supposed to be 12.7mm (0.5 in) from the
edges of the actual part.  If there are flaws anywhere within the
"entire A/B coupon", there is a strong probability that there are flaws
in the product as well.  Low pressure areas around a coupon could just
as well exist around a part, since it is indicative that the internal
borders are not well thought out. Coupons are intended to represent the
board.  You do not state whether the lam voids are after thermal stress
(delamination from the edge??) or how the specimens are removed from the
panels--N.C. routed just like the part (I assume), or were they
"sheared" from the routed frames afterwards.  Lots of unanswered
questions that you should work out with the test lab and the supplier.

Dennis J. Cantwell
R & D Liaison
Printed Circuits, Inc.
1200 West 96th Street
Minneapolis, MN 55431-2699
952-888-7900
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-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Menuez,
Pete (IE) @ CIN
Sent: Thursday, July 20, 2006 4:06 PM
To: [log in to unmask]
Subject: [IPC-600-6012] Inspection area of coupons

All:

We have a third part lab perform full Group A inspection on all boards
we buy for Space Flight.  This lab takes unused A and B coupons, pots,
reads and reports. We have recently come up with a situation that is not
clearly identified in either of the board specs 6012 or 6013.  

The question simply stated is 'does the entire mounted coupon get
inspected or is there a defined measurement that says inspect everything
within these boundaries'.  

What happened is this. The lab cross sectioned some rigid flex boards
and rejected them because of laminate voids.  The laminate voids are
located more than .100" from the nearest hole.  6012/6013 do not clearly
state how far away from the hole you inspect the cross section.  In this
case the non conformance is located in a low pressure area - in an area
where there is no copper at all in a .250" thick 27 layer board.  This
lack of foil does not happen on the board itself.  This is a somewhat
irrelevant fact because the lab isn't being asked to be a lamination
expert. I just thought I'd throw it in because someone might ask why
there are lam voids.

The spec defines Zone A as the entire hole/pads plus .003" past the
farthest reaching pad, internal or external.  Zone B is defined as the
space between the holes minus the .003" that was given to Zone A.
Reference figure 3-8 in IPC-6012.

My interpretation is that the evaluation zone therefore extends from
.003" to the left of the farthest left hole to .003" to the right of the
farthest right hole and that any area outside this is not to be
evaluated. Is this the correct interpretation or is there something that
says you have to look at more of the coupon? 

For some reason the picture in IPC-6013 that depicts the inspection area
only shows two holes.  I would assign the same logic as I did for 6012.
No matter how many holes there are in the coupon the inspection zone
stops 3 mils to the left of the left hole and 3 mils to the right of the
right hole.

Finally regardless of which interpretation is correct I believe there
should be a clear statement in each of the specifications stating the
boundaries.

Thanks for your time,



Pete Menuez
Supplier Quality Engineer
L-3 Communications Cincinnati Electronics
7500 Innovation Way
Mason, Ohio 45040
[log in to unmask]

513-573-6401 Voice
513-573-6767 Fax







 



Pete Menuez
Supplier Quality Engineer
L-3 Communications Cincinnati Electronics
7500 Innovation Way
Mason, Ohio 45040
[log in to unmask]

513-573-6401 Voice
513-573-6767 Fax