Jeff,

By inerting the solder pot only is a method to reduce nitrogen consumption
but still retain 95% of the benefits of the process.  Most of the benifits
of using nitrogen are at the wave and most important at the point of exit
from the wave.  Inerting the preheat section is more to reduce any
oxidation that may occur during this part of the process that the flux does
not prevent.  With good quality board plating and the right flux and
preheat the use of nitrogen in the preheat section is not required.  If
running copper/OSP boards that have already been through a couple of
reflow/cure cycles then having an inert preheat section will help retain
what solderability is left and prevent futher oxidation.  If your system is
operating correctly and the waves are inerted try this test and it will
make a beliver out of you.  Run a board with parts through your machine but
do not flux the board. Now run a board without flux and with the nitrogen
turned off.  WOW is what most people say.

Ken Kirby
Wavesolder product specialist
Speedline Technologies





 (Embedded
 image moved   Jeff Guynn <[log in to unmask]>
 to file:      08/27/99 05:47 AM
 pic26856.pcx)




To:   [log in to unmask]
cc:    (bcc: Kenneth Kirby/ElectrovertUS/Cookson)
Subject:  [TN] Nitrogen use with Solder Wave?




Hi everybody!

I was just wondering how much nitrogen folks are using in their low-residue
wave
solder process. How many of your solder wave stages are you using nitrogen
for?
I'm pretty much a solder wave newbie where I work. We're running nitrogen
over
the solder pot only. I know that nitrogen is supposed to "open up" the
process
window, which is especially critical with a low-residue (no clean) process.
Seems to me that just pumping it over the solder pot doesn't do much to
open up
the window prior to soldering.

Any input is greatly appreciated. Now that I've actually asked a question
I'll
have to try and come out of my lurker shadows a little bit more. :)

Thanks!

Jeff Guynn
Manufacturing Engineer
United Technologies Electronic Controls

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