I am not an expert but I can speak from experience in a previous life.
We used to use 99.999% N2 from a cyrogenic tank on a selective and as a
cost cutting measure we went to 99.9% N2 from our membrane generated
system and there about every solder joint was bridged. We went back to
the higher purity level and made absolutely no other process changes and
the bridging disappeared. 



Tom  

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Todd, Richard
Sent: Thursday, December 13, 2007 10:39 AM
To: [log in to unmask]
Subject: [TN] Nitrogen Generation for Wave & Selective Soldering

TechNet,

We currently have 3 Pb-free wave solder lines (in air) and 5 Pb-free
selective solder machines (using N2).  I expect the number of selective
solder machines to increase.  Currently, our N2 is stored as liquid and
converted to gas for the soldering applications.
I am looking at using a nitrogen generator instead of the costly liquid.
I did a search of the TechNet archives but didn't find anything that
really answered my questions.
Can anyone provide any assistance?  What levels of purity are required
for Pb-free soldering?  What types of systems are available (membrane
and PSA)?  Pros and cons?  Suggested vendors?

Any and all assistance and suggestions would be most welcome.

Regards,

Rick Todd
Senior Engineer
Panasonic Automotive Systems


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