Dave,

I can not comment with respect to waves, etc., but in previous life when working with Sn62/36/2 on Pd/Ag metallization on LTCC, using a water soluble flux system, I found that <20 PPM oxygen made for much better looking joints than say 50 ppm.  It also resulted in much better wetting.  It was a real small reflow set-up, was tightly sealed, and did not consume much nitrogen

We used cryogenic nitrogen.  Getting down to 5-10 ppm oxygen was the best that I could ever do (based on the old Teledyne oxygen analyzer with a 'fuel' cell).

I believe that I did my conversions correctly below.  Let me know if I am in error - 


99.998% - 20 ppm contaminate
99.5% - 5000 ppm contaminate
99.99% - 100 ppm

Steve Creswick - Gentex Corporation


-----Original Message-----
From: Dave Hillman [mailto:[log in to unmask]]
Sent: Tuesday, March 09, 2004 1:00 PM
To: [log in to unmask]
Subject: [TN] Nitrogen Purity Question/Survey


Hi folks! Question for those folks using nitrogen for an inert atmosphere
in their reflow processes or as a blanket gas on their wave solder
processes. Cryogenic nitrogen is typically 99.998% purity (in terms of O2
content). On-site nitrogen generation equipment can deliver N2 gas ranging
from 99.5% to 99.99% purity (again, in terms of O2 content). What gas
purity level are you using in your processes and do you have a rationale
for selecting that purity level?  The reason for the question is that I am
involved in an exercise of comparing on-site nitrogen generation versus
cryogenic nitrogen supplies.

Thanks in advance for you assistance.

Dave Hillman
Rockwell Collins
[log in to unmask]

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------