It's always good to get a view from a cross-section of our Industry, regardless of how well polished it was or not.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephen gregory
Sent: Friday, June 11, 2010 8:21 AM
To: [log in to unmask]
Subject: Re: [TN] Weird formation of voids

Hi Bev!
 
Got your picture today, and have it posted now:
 
http://stevezeva.homestead.com/Bevs_Ball.jpg
 
Almost looks like little pieces of dross. I wonder if something is going on with the solder paste? Or leaded reflow profile with a lead-free BGA?
 
Steve

--- On Wed, 6/9/10, Bev Christian <[log in to unmask]> wrote:


From: Bev Christian <[log in to unmask]>
Subject: [TN] Weird formation of voids
To: [log in to unmask]
Date: Wednesday, June 9, 2010, 9:51 AM


TechNetters,
I am sending a picture to Steve to post.  I have labs in three locations.  One of them has seen weird voids in cross-sections of BGAs while the other two locations have not.  For the lab that has seen them, the cross-sections were prepared by different people on different days for different products, using the same equipment. The voids are not in all balls cross-sectioned but may be only in one of two of the balls in a row of multiple solder joints examined.

Have you seen anything like this?  Do you know the root cause?

Vlad,
You know what is going on, so please don't respond.

Bev


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