Denny,
I had similar questions as the ball did not seem to wrap around the right side of the pad as it does on the left side due to slight misregistration.  Actually the foil to laminate adhesion appeared to be excellent as the pad in picture C-1 tore away a huge section of the laminate.

Happy New Year to All.

Regards,
Scott A. Bowles
Director of Engineering and Quality
Hallmark Circuits, Inc.
13500 Danielson Street
Poway, CA 92064
 
858-513-2200 Phone
858-513-2233 Fax
858-437-7827 Cell


-----Original Message-----
From: Dennis Fritz [mailto:[log in to unmask]]
Sent: Tuesday, December 30, 2008 4:35 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Pad to trace interface on BGAs.


Chris - 

Great pictures - my compliments.?? Open the Mahanna school of sectioning. 

Question - slight mis-registration of balls to board seems to initiate trace cracking.? First image is well registered, but obviously cratered.? In image 3 - the "cracked copper" does not seem to come from the attachment pad. Is this a bit of the circuit trace to the pad that has mostly been ground away?? Image 7 looks like the broken copper might? have come from the pad on the board, but again does not quite fit "back together".??? 

Your sections are so precise that we can make these speculations.? 

Denny Fritz
MacDermid, Inc. 

-----Original Message-----
From: Chris Mahanna <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, 30 Dec 2008 11:21 am
Subject: Re: [IPC-600-6012] Pad to trace interface on BGAs.



Some cratering pics are attached.  Note the cracked foil on C-3 and C-7.
Chris



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