Too much paste?  Errant ball from somewhere else merged?  Size can be deceptive for the detective work.  Measure carefully and calculate the excess solder volume so you can start figuring out what the suspect looks like.  Or maybe gas evolved from the board somehow during reflow (assuming the overall volume is correct, and the only reason for the oversize diameter is the void inside).

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Tuesday, July 30, 2013 2:18 PM
To: [log in to unmask]
Subject: [TN] Singular 30% Void and Oversize Ball Diameter

Folks,

We run thousands of boards a day, and almost every one carries a BGA.  We inspect each with inline X-ray.

Last week, we had one single ball to fail for a 30% void and an oversize diameter.  We contacted the supplier, and they said their process was incapable of sending out such a defect.

We've never had a void over 5%, and even those are incredibly rare.

What within our process might have caused this, and do you agree with the statement of the supplier?  How do you recommend we analyze the failure?

Thanks in advance for your help!

Leland

________________________________

“Confidentiality Notice:
This transmission (including any attachments) may contain confidential information belonging to the sender and is intended only for the use of the party or entity to which it is addressed. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, retention or the taking of action in reliance on the contents of this transmission is strictly prohibited. If you have received this transmission in error, please immediately notify the sender and erase all information and attachments.”

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________