Steve, There has been a renewed interest in nitrogen at the reflow process. Much of this has been the increase in sandwich solder joints as seen with BGA technology. More oxides in the oven create greater flux activation and more outgassing. Some folks have done research that points towards a 180-200ppm level in reflow to reduce BGA voiding. Other than reduction in voiding, the effects of nitrogen are very much a subject of discussion among production. Some parts of questionable solderability (perhaps old parts with quite a bit of oxidation) can benefit from nitrogen. Nitrogen is a good safety net for BGAs because when you look at the area that the flux must clean on the ball and pad, the surface area is probably 3 times greater than that of a QFP lead and pad. If you are not getting into BGA technology, or some old no clean paste that requires an inert atmosphere, then I am not sure if there will be a major benefit- hence, breaching 180ppm would not be that much of a problem for you. Hope this helps. Steve A > -----Original Message----- > From: Shoda, Steve [SMTP:[log in to unmask]] > Sent: Friday,August 31,2001 9:51 AM > To: [log in to unmask] > Subject: [TN] Nitrogen Purity for SMT IR Reflow > > Our facility is considering changing from stored liquid nitrogen at > 99.9999% > purity to onsite generated at 99.5% purity (5000ppm impure). Our reflow > manufacturer recommends a maximum of 180ppm oxygen in the nitrogen > environment. What problems could occur if the 180ppm level is breached? > What maximum impurity levels have been observed without any adverse > effects? > > Thanks in advance for your inputs. > > Steve Shoda > BAE SYSTEMS Controls > Fort Wayne, IN > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > ------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------