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August 2014

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From:
Robert Kondner <[log in to unmask]>
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Date:
Wed, 6 Aug 2014 15:11:11 -0400
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Newbie Question:

 Why do the images look like vanilla ice cream with cookie crumbs?  

 Why the very inconsistent mixture in the solder?  At first I thought it was
just some coloring issue but the cracks seem to propagate along the
interfaces.

I would think the solder would be a better amorphous mixture. Could that
solder filled with dross?
 
Bob K.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Wednesday, August 06, 2014 2:49 PM
To: [log in to unmask]
Subject: [TN] SJ fracture signature

We see hundreds of cracked solder joints every year, but I can't say that
I've ever seen one quite like this.  I have some suspicions, but I'll keep
them to myself, as to not prejudice the crowd.
EDS maps are forthcoming.

This is a caught in-the-wild field failure of a 48-pin BGA Reballed to SnPb
ENIG on board side Ni barrier on component side

http://stevezeva.homestead.com/45268-1.JPG

http://stevezeva.homestead.com/45268-2.JPG

http://stevezeva.homestead.com/45268-8.JPG

Thoughts?  And Thanks to Steve!


Chris Mahanna
President, Technical Manager
Robisan Laboratory Inc.


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