Neil, I echo Dave Hillman's response, but with a few caveats. Up to January, 2005, I thought that it was required to use Nitrogen with Lead Free solders. Since then, having run hardware without Nitrogen and with Nitrogen in our Demostration Factory, plus the work done on the JG-PP / JCAA Lead Free Program, I feel that Nitrogen is not required but a good option to have. Controlling your inventory environment will reduce the probability of hardware becoming oxidized which will lead to poor solderability. The GIGO - garbage in garbage out - rule applies in this case. Hardware thought to be acceptable with Tin Lead (SnPb) may not be acceptable for Lead Free alloys because these alloys do not wet as well as Tin Lead (SnPb). Of course you can use a really active solder flux to get the alloy to wet better, but then your cleaning processes would have to become more aggressive to remove the residues. Nitrogen will reduce the amount of residues on the board and the solder joints will look brighter. It will open that process window to solder hardware which may be marginal. With Tin Lead (SnPb), using Nitrogen it may be possible to solder marginal material (boards, components, etc.)depending on how bad the material is. However, since most Lead Free alloys do not wet as well as Tin Lead (SnPb), if you have marginal material, Lead Free soldering may be more difficult. If you don't have Nitrogen, you probably would have to control your inventory tighter than for Tin Lead (SnPb). If you have Nitrogen, then save it for emergencies and use it as required. A potential thought would be to use a Nitrogen Generator but I don't know if there are any available that can support a reflow oven or wave soldering system. I heard some rumors that there are but I have no first hand knowledge. Hope this helps. Good luck. Lee Whiteman Senior Manufacturing Engineer American Competitiveness Institute E-Mail: [log in to unmask] Ph: (610) 362-1200 x208 Fax: (610) 362-1290 This message is for informational purposes only and does not supersede, modify, or create any agreements with ACI. Information contained in this message does not bind ACI or its affiliates to any commitment, either express or implied, unless ratified in writing by an authorized representative. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Neil Maloney Sent: Wednesday, January 18, 2006 3:32 PM 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/> --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------