Nitrogen reduces the oxide burden on the flux (good), but also tends to
increase solder surface tension (not so good). So the total overall benefit
you will get depends (as usual ) on your specific circumstances (work type,
reflow machine abilities, as well as fluxing abilities of your paste). Just
about all paste suppliers have set out to make their lead free pastes air
reflowable and I would suggest that the cost benefit ratio is probably only
a little different to that for leaded pastes given a competent supplier.
Certainly we have very virtually no nitrogen users [in reflow]. Off the top
of my head I would say the only ones using nitrogen lead free were the ones
using it when soldering leaded.
Hope this helps.
Regards
Mike Fenner
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
E: [log in to unmask]
W: www.indium.com
Pb-free: www.Pb-Free.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Neil Maloney
Sent: 18 January 2006 20:32
To: [log in to unmask]
Subject: [TN] Time to fish or cut bait
Greetings, Technet!
My company is making the transition from leaded to lead -free assembly in
the US (we have already converted our overseas facility) Now we are
in the throes of the N2 vs. air battle. Our overseas unit uses air
only without any problems (ENIG boards, 0602s to QFPs, no BGAs) In
the US we are looking to start designing BGA and flip-chip assemblies with
the same type ENIG and Entek boards. We are buying a new 10 zone reflow
oven, and battle begins. Do we start with nitrogen or not? Can a small
company make lead-free BGA assemblies without going to an N2 atmosphere?
Does air make the process window too small for BGA?
Our smallest PCB is about 8x12cm.
Thanks in advance
Neil Maloney, Manufacturing Engineer
Contemporary Control Systems, inc
2431 Curtiss St Downers Grove, IL 60515
(630) 963-7070 x132
[log in to unmask]
http://www.ccontrols.com <http://www.ccontrols.com/> http://www.ctrlink.com
<http://www.ctrlink.com/>
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