Conduction reflow would help. In theory, you have few degree difference between the fully formed solder joint (old joint) and fine solder sphere paste for reflow. The paste would reflow a bit lower temperature. As long as all the surface tension still hold for the old joint, you should be OK, unless the components is in the "cavity down" and weight a bit too much = can't hold by surface tension..... ;-(. jk >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of Rick Thompson >Sent: Thursday, April 24, 2003 12:46 PM >To: [log in to unmask] >Subject: [TN] 'Unique' BGA Reflow Problem > > >We have a customer who had a custom BGA built with some >additional components besides the die under the encapsulant. >Unfortunately, these parts were soldered with Sn63Pb37 and the >solder reflows and bridges under the encapsulant during >reflow. Due to time constraints they would like to find a way >to use these while they wait for new parts to be fabbed. >We've tried various types of shielding, but the convection >systems we have heat the entire part causing the internal >reflow. Does anyone know of a focused reflow system that >would allow reflowing the eutectic balls of a BGA but not >apply enough heat to the top of the component to reflow the >other parts? Would one of the focused IR systems (Ersa, PDR) >do this? Other possibilities? > >Thanks in advance. > >Rick Thompson > >Sr. SMT Process Engineer >SMTEK International, Inc. >+1 (805) 532-2800 >[log in to unmask] > >--------------------------------------------------- >Technet Mail List provided as a free 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/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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------