Susan, in your expert opinion, will passing this float method test preclude delamination and z-axis expansion leading to via cracking in a standard 63/37 SMT oven reflow process? What about for a 250 C Pb-free reflow process or condensation reflow process? The reason I ask this question is because many BGAs now come only with lead free solder spheres, but they are soldered using tacky flux (no solder paste) in a slightly elevated temperature profile (TALT = ~230C for 60 sec) along with all of the other standard 63/37 components. Also, many CMs and OEMs are going back to using condensation reflow to get more uniform heating for a lead-free process. Is the float test good enough to qualify the pwb to withstand these assembly processes? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Susan Mansilla Sent: Tuesday, May 30, 2006 7:16 AM To: [log in to unmask] Subject: [TN] Dip or Float Thanks for confirming what you are actually doing in this test. We have come up against the two different styles and have had trouble correlating results. By dipping the process simulates a Hot Air Solder Leveling process. All of the stresses are equal since both "sides" of the board see the same heat at the same time. The float has a really hot bottom and a relatively cool top. This allows (causes) z-axis expansion that weeds out both barrel cracks and inner layer separations. There are no IPC test methods that call for dipping other than the solderability tests. Thanks again for the clarification Susan --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------