Can't give much of an insight from experience, but I know that PBGA's
solder beautifully simply using flux. Paste is used to mount them during
initial assembly, simply because all the other components require it and
it's difficult to just flux the BGA's alone.
For re-work, though, you can concentrate on the BGA alone. You don't need
mini stencils and little squeegees - you just remove the old component,
clean up the site with a solder sucker (don't use wicks), apply flux to the
component contacts, place and reflow. The experts (Atmel/Thomson) tell me
it works a treat and have it written up as a guideline.
It doesn't work for CBGA's, which have 90/10 solder balls that don't melt
during reflow. These do require solder paste to replace them.
Peter
Jeff Ferry
<jferry@CIRCUITTE To: [log in to unmask]
CHCTR.COM> cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST
Sent by: TechNet Aero/ST Group)
<[log in to unmask]> Subject: [TN] BGA Rework Using Paste vs. No
Paste
02/01/02 12:54 AM
Please respond to
"TechNet E-Mail
Forum."; Please
respond to Jeff
Ferry
Fellow TechNetters,
We nearly always apply solder paste to the circuit board when we replace
BGA components during rework. Yet, after speaking with a handfull of BGA
equipment companies at APEX, seems like they all recommend using flux only
vs. paste, unless the circuit board is used in a high rel application.
What do ya'all do/recommend for BAG rework? Can you point me to any
studies/reports on the subject?
Thanks,
Jeff Ferry
CEO
Circuit Technology Center, Inc.
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