Hello Vladimir, There is a lot of work going on right now evaluating the impact of the ternary IMCs. In fact some major system companies are banning the use of Ni on pads to receive solder. This is causing a lot of work for BGA product manufacture and second level assembly. With reflow thin Ni3Sn4 layer forms on the Ni. Then a ((Cu(6-x)Ni(x))Sn5 layer forms due to the presence of Cu in the SAC. The risk interface is between the two phases, which have very different microstructures. Going to OSP coated Cu or direct Au on Cu results in other concerns. It appears that such an interface results in a thin Cu3Sn layer on the Cu, and then a thick Cu6Sn5 layer forms between the Cu3Sn and the SAC solder. In SOME cases it appear that Kirkendall voiding develops between the two Cu-Sn IMC layers, and for other PCB lots, the voiding does not appear. Best regards, Leo Leo M. Higgins III, Ph.D. Vice President Technical Support Operations ASAT, Inc. 3755 Capital of Texas Highway, Suite 100 Austin, Texas 78704 ph 512-383-4593 fx 512-383-1590 [log in to unmask] www.asat.com The information contained in this electronic message is CUSTOMER/SUPPLIER PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution and copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by electronic mail. Thank you. -----Original Message----- From: Vladimir Igoshev [mailto:[log in to unmask]] Sent: Friday, November 11, 2005 12:48 PM To: [log in to unmask]; [log in to unmask] Subject: Re: [TN] RE urgent issue BGA fall out Hi Leo, Could you, please, elaborate what you mean? What you've stated sounds rather unusual, at least from what I know. I've never heard of Cu being "a bad element causing embrittlement" in solder joints. Regards, Vladimir Sent from my Blackberry Wireless Vladimir Igoshev, 519-888-7465 ext.5283 -----Original Message----- From: TechNet To: [log in to unmask] Sent: Fri Nov 11 13:35:13 2005 Subject: [TN] RE urgent issue BGA fall out Based upon past experience, it is not necessary for black pad to be present for brittle failure to occur with SnPb solder balls. With use of SAC solder balls, the addition of Cu in the ball could be further complicating the intermetallic phases present at the solder to Ni interface with the formation of ternary Cu-Ni-Sn IMCs. When you commingle this with possible interfacial Ni-Phosphide phases that may result due to variations in P-content in the Ni, and higher reflow temps, you could further embrittle the interface. Best regards, Leo Leo M. Higgins III, Ph.D. Vice President Technical Support Operations ASAT, Inc. 3755 Capital of Texas Highway, Suite 100 Austin, Texas 78704 ph 512-383-4593 fx 512-383-1590 [log in to unmask] www.asat.com The information contained in this electronic message is CUSTOMER/SUPPLIER PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution and copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by electronic mail. Thank you. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of WTSJ-Willis Tam Sent: Friday, November 11, 2005 3:47 AM To: [log in to unmask] Subject: [TN] ??: [TN] urgent issue BGA fall out Hi Ofer, What did you do to fix the issue? Thanks Willis Tam -----原始邮件----- 发件人: TechNet [mailto:[log in to unmask]]代表 Ofer Cohen 发送时间: 2005年11月11日 17:38 收件人: [log in to unmask] 主题: Re: [TN] urgent issue BGA fall out 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] org: 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. Any use of this information by anyone other than the intended recipient is prohibited. If you have received this transmission in error, please immediately reply to the sender and delete this information from your system. Use, dissemination, distribution, or reproduction of this transmission by unintended recipients is not authorized and may be unlawful. --------------------------------------------------- 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 -----------------------------------------------------