Hello Lina,

Were you continually monitoring resistance change throughout temperature cycling or only at room temperature outside of chamber?

If only at room temperature, you are not seeing the z-axis thermal expansion which would open up the barrel crack completely to see an open circuit at elevated temperature, there is a proximity contact evidenced by increased resistance at room temperature.

Best Regards,
Phil.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of li na
Sent: 07 September 2006 07:40
To: [log in to unmask]
Subject: [TN] PTH barrel crack

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Hello All,

We recently met one problem when we were doing 1000 cycles thermal cycle
test(-40C to +125C) on daisy chain boards.  The resistance change after
1000 cycles is less than 10%, however we see complete barrel crack on PTH
hole walls. Should I accept or reject this test result?  Have you ever met
this kind of problem before?  What did you do on it?

Your advice are highly appreciated.

Best regards,
Lina

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