Keith,

Other "tricks-of-the-trade" include picking a short (length) suspected trace
and trying to pinpoint the open location. Either using a TDR, ToneOhm,
DMM, xray, dremmel, or whatever....cross section down to the location
to perform failure analysis. I have even seen people use portable belt
sanders with fine sand paper to remove a layer at a time to determine the
inner layer issues. (It's not easy)  I think there are facilities out there
that
might perform this task.

Good Luck,

-David Hoover
----- Original Message -----
From: "Keith Calhoun" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, November 12, 2003 7:15 AM
Subject: [TN] Inner layer open trace


> hoping that Technet could once again help me with a vexing problem.  We
> have had a number of boards which have been returned from the field that
> fail during our testing.  We have identified the problem as an open
> trace on an inner layer between one or more IC's and the card edge
> connector.  All of these opens appear to be found on the same inner
> layer, and all the boards which show this failure have the same date
> code on the bare boards.  We have tried to have these boards x-rayed to
> determine if we could find any problems, but we were unable to locate
> any problems.  We can identify the area on the boards as being somewhere
> in about a 2-3 sq. in. area.  I am interested in finding out about any
> other methods, sources, etc which we can use prior to destructive
> investigation of this problem.  Again your help is greatly appreciated.
>
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