Hi Richard, Ingemar is absolutely correctthe only way you know what the t's are at the solder balls is to put thermocouples in them. It is indeed standar5d procedure see IPC-7530, 7.9.5. BGA solder balls get heated by conduction through the PCBmany people do not realize thisand BGA component body is in fact a heat sink and a shield preventing both convection and radiation heat transfer. Regards, Werner Engelmaier 可靠性先生 Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Cell: 386-316-5904 Werner Engelmaier --------------------------------------------------- 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 -----------------------------------------------------