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July 2009

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Subject:
From:
Steven Creswick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steven Creswick <[log in to unmask]>
Date:
Sat, 4 Jul 2009 13:16:09 -0400
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text/plain (78 lines)
Gaby,

I took the images and played with the contrast and gamma a bit.  One can not
tweak too much because of the small image size to begin with, but this
allowed me to see the solder mask, etc.

Of particular interest is image "small1".  It appears that the anomaly
actually extends beyond the body of the solder bump and out into the
underfill/potting and re-surfaces as the 'hole' to the right of the defect.

My first reaction was that these were inclusions of some type of foreign
matter in the solder joint.  It did not look like alloy constituents from
the photos provided.

Steve

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gabriela
Sent: Saturday, July 04, 2009 3:54 AM
To: [log in to unmask]
Subject: [TN] Weird solder joints

Dear all,
By cross sectioning BGA solder joints on a failed assembly, I found that the
suspected joints are not uniform and that they contain unusual separation
areas.

I suspect mixed assembly and/or bad reflow profile.

Steve was so kind and enabled me to send the links.
Please may I have your opinion?
http://stevezeva.homestead.com/files/small.jpg

 

 <http://stevezeva.homestead.com/files/small1.jpg>
http://stevezeva.homestead.com/files/small1.jpg

 

 <http://stevezeva.homestead.com/files/small2.jpg>
http://stevezeva.homestead.com/files/small2.jpg

http://stevezeva.homestead.com/files/small3.jpg

 <http://stevezeva.homestead.com/files/small4.jpg>
http://stevezeva.homestead.com/files/small4.jpg

 


Gaby


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