Hi Ramon, What do u mean by wet? Do you mean melt? ........What reflow profile was used? If SnPb temperatures were used, then SAC balls will not reflow and form a homogenous joint, which creates reliability issues........a sort of a hybrid profile is needed to solder backward compatible BGAs using SnPb solder.....depending upon the % of solder volume of SAC BAG to the % of solder volume of SNPb on the pad, the SAC can melt anywhere from 210 to 215 degree C. the key is to hold it above that temp just enough to melt all the SAC and dissolve it in the SnPb to form a homogenous microstructure, but not to overheat the SnPb components Wow! Haven't seen the Mixed BGA scenario....not yet atleast! Amol Kane M.S (Industrial Eng.) Process Engineer Harvard Custom Manufacturing 941 Route 38 Owego, NY 13827 Phone: (607) 687-7669 x349 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon Sent: Friday, June 02, 2006 9:55 AM To: [log in to unmask] Subject: [TN] BGA solder Two experiences were shared with me and would like them to be known for comments. In one instance a COTS BGA was used on a prototype. It would not wet to SN63Pb37 after several attempts and profile temperature increments It was found out that it had SAC 305 balls. Has anyone experienced that SAC does not wet well with eutectic tin lead solder paste? In another instance balls from SAC and Tin Lead were found in the same BGA. Apparently solder balls were inadvertently mixed. Ramon --------------------------------------------------- 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 -----------------------------------------------------