This sounds like either typical black pad problem, or a passivated Ni surface under the very thin immersion gold layer. A determination of the failure interface as suggested by another respondent is necessary. A cross-section of a failed interface and an unseparated interface from the same sample set would help in making a diagnosis (SEM / EDX map and line scans for O, Ni, Sn, P). A scanning Auger map of the surface can help in seeing if the Au deposit is low density or porous, and if it has allowed Ni to oxidize and prevent good wetting after the Au is dissolved in the solder. Regards, Leo ------------------------------------ Leo M. Higgins III, Ph.D. ASAT Inc. Central Region Mgr. / Director of Sales [log in to unmask] 3755 Capital of Texas Hwy-So Suite 100 Austin, TX USA 78726 tel: 512-383-4593 fax: 512-383-1590 mobile: 512-423-2002 ------------------------------------ -----Original Message----- From: karpinski [mailto:[log in to unmask]] Sent: Wednesday, February 18, 2004 3:38 PM To: [log in to unmask] Subject: Re: [TN] Ni/Au solderability on kapton Hi Vladimir, As I know it is Pd. regards Vladimir Igoshev schrieb: >Hi Waclaw, > >Do you know what material (Pd or Ru) your board supplier uses to deposit electroless Ni? > >Vladimir Igoshev, >Research in Motion > >Voice: (+1) 519-888-7465, ext. 5283 >Fax: (+1) 519-886-0863 >E-mail: [log in to unmask] <mailto:[log in to unmask]> > > >-----Original Message----- >From: karpinski [mailto:[log in to unmask]] >Sent: Wednesday, February 18, 2004 4:15 PM >To: [log in to unmask] >Subject: [TN] Ni/Au solderability on kapton > > >Recently we have solderability problems with Ni/Au kapton flex boards >(0,1 µm Au, 3 µm Ni, 35m Cu). >We have produced and assembled large number of boards. >On 10 % of the boards we observe interconnection failures after final >assembly of the pcbs. If the suspected solder joints are lightly >stressed , the connections are easily broken, leaving an open circuits. > It is easy to peel these parts with solder material from the boards. >The pads below the removed parts are discolored dark gray and are sleek . >Some times the handsoldering of the broken joins was successful but >after small strain the joints broke again. >Additional vapor phase soldering did not improved the the strength of >the joints. >This is new problem for us. Does anyone have any experience with this? >How to rework the boards? How to determine when a board should be >reworked or >scrapped? What about reliability issues? Latent failures? >I would appreciate your help very much > regards > >-- >Waclaw Karpinski >I. Physikalisches Institut >RWTH Aachen >D - 52074 Aachen > >--------------------------------------------------- >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 847-509-9700 ext.5315 >----------------------------------------------------- > >--------------------------------------------------- >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 847-509-9700 ext.5315 >----------------------------------------------------- > > > > -- Waclaw Karpinski I. Physikalisches Institut RWTH Aachen D - 52074 Aachen Sommerfeldstr 14, Turm 28 Tel.: +241 802 7181 Fax.: +241 802 2623 Mobil: 0049 173 70 22 548 --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------