Willis, Welcome to the black group of the black pads. We've experienced the phenomena lately. The balls were left on the PCB, while the BGA, leg-less, fell off after the soldering. Failure analysis showed clearly balck pads phenomena on the BGA substrate. Ofer Cohen Siemens > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of WTSJ-Willis Tam > Sent: Friday, November 11, 2005 08:31 > To: [log in to unmask] > Subject: [TN] urgent issue BGA fall out > Importance: High > > > Dear All, > > > > Recently, we found a very strange defect with the BGA IC. > > > > Here's our process flow: SMT---> De-panel (by V-cut machine)---> > > Functional test--->final inspection > > > > We found around 10 pcs BGA falling out either at the process of > > de-panel or functional test, defect rate less than 0.1%. The defect > > only happened in 2 days, It's very strange, all the solder > balls adhere to PCB. there's no > > solder ball adhere to the BGA substrate. > > > > Investigations from our side: > > 1. We have been built the same product since April 2004. no > issue before. > > 2. Since May 2005, the SMT process was converted to RoHS, > BGA also has > > been changed to green type since then, monthly output around 200K. > > 3. The BGAs were 100% baked under 110 degreeC for 24 hrs before SMT. > > 4. We use Loctite LF318 solder paste for SMT, the time between 70 > > degreeC to peak 245 degreec is around 250 seconds. > > 5. The BGA only subjected to 1 time reflow (only 1 side with > > components) 6, We have reflow fixture to support the board during > > reflow. there's no warpage issue. > > 7, Use Vcut machine to separate the units from a 6 up-panel PCB, no > > extra stress to the board. > > 8. Use pogo pin to make connection for functional test fixture, no > > extra stress. > > > > Information of BGA. > > 1. It's a solder mask defined substrate. with ENIG surface > finishes. > > 2. 0.8mm pitch, pad size 0.35mm. > > 3. IC supplier apply solder ball with flux only, without > solder paste. > > > > Would anybody give me some advices, what shall be the most possible > > root cause? it's a BGA IC issue or a SMT process issue? How > to improve? > > > > > > Thanks > > Willis Tam > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------- > 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 -----------------------------------------------------