Gerald,
I suspect ACI Technologies has some data on this, though I don't have it
at my fingertips. Try Fred Verdi: [log in to unmask]

Li, Poranki, Srihari et al at SUNY Binghamton coauthored a paper with a
couple of Sanmina-SCI folks at SMTAI in 2009: "Reliability Assessment of
Reballed BGAs." A quick Google search suggests lots of places have
decided to "borrow" it from SMTA ( :-) )
Here's one:
ftp://wilbur.eng.auburn.edu/pub/zhangj2/experiment%20paper/reliability%2
0assessment%20of%20reballed%20BGAs.pdf


There also are described methods that avoid some of the heat cycles
associated with desoldering and resoldering.

BEST has written about its manual wicking braid process, which
eliminates one of the thermal excursions:
http://circuitsassembly.com/cms/component/content/article/201/8397-bga-r
eballing-reliability

And our (TechNet, I mean) own Dean Stadem has written about a laser
method that avoids two thermal excursions:
http://circuitsassembly.com/cms/component/content/article/199/7193-solde
r-ball-attachment-using-laser-soldering

Best,
Mike

Mike Buetow
Circuits Assembly
w/m 617-327-4702

>>> The CIRCUITS ASSEMBLY EMS Directory -- over 2,100 listings, in Excel
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerald Bogert
Sent: Wednesday, June 01, 2011 3:22 PM
To: [log in to unmask]
Subject: [TN] Re-balling BGAs

June 1, 2011

 

Anyone have technical data to support (or not support) re-balling of
BGAs to change from SAC balls to Pb balls???

 

My understanding is that because of the extra heat cycle involved, BGA
manufacturers may not stand behind their part warranty if re-balling is
done.  I also seem to recall a technical poster or paper presented at
IPC several years ago which I believe indicated a reduction in
reliability of the part if it is re-balled.

 

Also seems to me that if one were to re-ball a BGA, this would be a
repair and not a reqork process and as such may require specific
customer approval.


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