Hi Jonathan! One possible cause for the nonreflow would be oxidation of the solder spheres in the solderpaste. (your photo didn't make it thru the IPC server - could you have Steve post it on his website?). If you can reflow the paste in a forming gas environment but not in a standard N2 blanket environment then either your solderpaste flux is defective or that the solder spheres are so heavily oxidized that the solderpaste flux doesn't have a chance to do its job. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Jonathan A Noquil <[log in to unmask]>@IPC.ORG> on 07/25/2001 07:07:03 AM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to [log in to unmask] Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: [TN] Non-Reflow Hello Friends, Can anybody explain why there is always a non-reflow of solder paste as shown by the drawing below? (Embedded image moved to file: pic07711.pcx) The solder paste used for assembly was 88Pb10Sn2Ag and it is an Indium No clean paste. Its liquidus temp was 290 C and solidus temp of 268 C. Reflow Atmosphere: N2 purge as hot gas and cool gas (shown at the above drawing) although we tried to increase the temp to over than 300 C, it is still the same results. I tried the paste to other oven with a forming gas blanket, and reflow it to a peak of 295 C the results were good (All reflowed). We had profiled the above oven at 3 points Left edge, Midle and. Right edge and temperature difference vs setting was ± 5 degree C on that three points. Was the non-reflow due to the blanket? O2 ppm level? But why on the left side only? Does a localized heating have occured? But the temp profile was okay? Do you have any insights that you can share? God Bless You All... Thanks --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------