Was it a powered thermal cycle? In case yes, I agree with Rigo, CAF is one possibility as well as ECM is (was humidity available as well?), in case not powered, a Tin Whisker might be another potential root cause...

-----Ursprüngliche Nachricht-----
Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Garcia, Rigo (GSFC-300.0)[MANTECH SRS TECHNOLOGIES]
Gesendet: Dienstag, 27. März 2012 14:27
An: [log in to unmask]
Betreff: Re: [TN] Short after assembly

CAFs?

Rigo

Sr. Quality Assurance Engineer
Workmanship Standards, Code 300
NASA, Goddard Space Flight Center
Greenbelt, MD  20771
Phone. (301) 286-6129
Fax.       (301) 286-6576

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pradeep Menon
Sent: Tuesday, March 27, 2012 7:33 AM
To: [log in to unmask]
Subject: [TN] Short after assembly

We had supplied a PCb to one of our high reliability customers 2-3 years back. Now we understand that in one of the PCB they have observed a low resistance short after thermal cycling. The bare PCB was BBT tested at our end and was also cross verified as a bare board by the customer. They had populated the board and the tests were all found compliant. After some time they say they observed a low resistance short. We are a bit perplexed on this. Can anyone share what can be the possible reasons for the same. We feel it may be even something to do with assembly as well. Can you pls provide some inputs

Rgds

Pradeep

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