It is difficult to unring a bell.  If there are laminate voids anywhere in the coupon that is in the mount, they should be evaluated to determine compliance.  You must rely on the test lab to have separated the individual coupons from the strip and you must rely on the board shop to have separated the strip from the panel in the manner that will not cause defects.  It seems like your reasoning is to "excuse" the presence of laminate voids rather than to have the board shop determine first of all if the voids are in their coupons and secondly how they got there.  It might also be relevant to examine a couple of boards near the coupons on the panel to determine if the voids are present within actual boards on the panel.
 
Susan Hott
Robisan Lab

________________________________

From: IPC-600-6012 on behalf of Menuez, Pete (IE) @ CIN
Sent: Thu 7/20/2006 4:05 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