Bill, 

Personally I think these types of anomalies are a minor concern as for as functionality or reliability. However, depending on your customers end use, the cosmetics of the part may be critical. Perhaps the "finished" product is only the assembly and it doesn't get  hidden in a case. I have had parts such as you describe rejected using the following logic.  My customer believed that if the if the dent was created after lamination, then either the glass/resin could have possibly fractured under the dent or the copper has been mashed which would spread the copper outward and reduce the copper thickness in the center of the dent. The logic seemed sound. In any case he was uncomfortable with using the part. Since the only way to disproved the logic was to cross section the parts and therefore scrap the boards, It simply was not worth the effort since the quantity was only a few parts. Fortunately I had another parts in stock so I simple replaced them. Anyway, that's my experience with dents.

Ed Cosper
Graphic Electronics Inc. 

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From:  72030,3271[SMTP:[log in to unmask]]
Sent:  Thursday, September 04, 1997 7:37 AM
To:  [log in to unmask]
Subject:  [TECHNET] FAB: Acceptabilty of dents

Fellow Tech-Netters:

Some of the high-volume single-sided boards we produce are punched. At times
we find repetitive dents on the surface of each board where a laminate chip
has lodged on the face of the die, causing a slight depression with each hit
until it is cleared away. These dents are typically no more than .050" in
diameter and do not cut foil or reduce cross section, just depress it a bit
into the base laminate (1/0 .062" CEM-1 or FR-4). Is anyone aware of an IPC
spec or other reason why these class 1 and 2 boards should be rejected?
In the absence of these, personal opinions on acceptability would also be
appreciated.

Bill Parlin