Keith,
We use to run down opens like this with a high voltage power supply connected to either side of the open net. If their was a resistive path left that would pass any current (but to small to see in x-ray) it would heat up and a piece of liquid-crystal plastic placed over the area would turn color to show us where the highly-resistive "open" was. Other wise, its a tough search!
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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