The melting temp for pure Sn is 232C and Pb is 327C. The combination of the two @ 60/40 is about 183C. Something caused melt separation into their pure states?. Mislabeled solder paste? It was actually Sn100. 2 cents -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord Sent: Friday, May 04, 2007 1:22 PM To: [log in to unmask] Subject: [TN] Metalurgists, need assistance Have an issue with (randomly) lifted FPGA leads. Pic 1: good joint after pull test Pic 2: ditto but high magnification Pic 3: "rotten" joint after pull test Pic 4: ditto but high magnification Pic 5: "rotten" cross section Pic 6: ditto but high magnification 60Sn on ENIG, obviously a brittle region. Suspect Kirkendall voids, but the pockets with zillions of Tin spheres (0.1 to 2 um in size) points at insufficient peak temperature to make 100% melt and good solidifying. If these little balls were Lead, I could understand, but they are Tin! Never seen like. Any "quickhead" out there, need fast advice. Note: Pic 2, you can see the underlying board pad nickel as dark areas. An experienced analyst will hopefully recognize. No Phosphorous peaks! My Friday headache. Inge --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 -----------------------------------------------------