Hi Ashok,
What you are seeing is the result of BGA PCB warping during cooling from reflow, resulting 
in different solder joint heights, and therefore different ball diameters looking down on the BGA.

 This can be a problem if the more squeezed balls are on the periphery, because SJ height is one of the four major parameters determining 
SJ reliability.

Werner


 

 

-----Original Message-----
From: Ashok Dhawan <[log in to unmask]>
To: [log in to unmask]
Sent: Fri, Jan 22, 2010 2:22 pm
Subject: Re: [TN] X-Ray Inspection


Bob

We are currently doing XRAY Inspection of BGAs. The XRAY TestEngineer
noticed that solder ball size on outer rows is different from the ball size
on inner core areas. 
"We are still seeing a bi-modal data distribution of ball volume between the
middle and periphery balls? Is that normal for BGAs. "

I would appreciate your expert comments as there is not much XRAY related
information on web.

Regards

Ashok Dhawan
Manuf. Specialist
Parker hannifin Electronic Controls
Winnipeg Canada
[log in to unmask]

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to 
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to 
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for 
additional information, or contact Keach Sasamori at [log in to unmask] or 
847-615-7100 ext.2815
-----------------------------------------------------

 

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------