OK - I don't know much about this FPC - it is 3-4 suppliers back in the chain, still working my way back... I do now know that there is actually a Ni Layer (3microns thick) with 3microns of Au on top. The copper is 34microns and the crack on one part (as I have received it) goes through the Ni and about 25% of the way through the Cu. I will try to get a photo to Steve. Neil>----Original Message----> From: [log in to unmask]> Date: May 2, 2008 11:41:12 AM> To: [log in to unmask], [log in to unmask]> Subj: Re: [TN] Fw: [TN] Brittle FPC Tracks> > Hi Neil,> Indeed, Au over Ni will result in diffusion. However, while AuSn IMC is indeed brittle and weak and weakens the solder structure, I do not know whether Cu-Au is particularly brittle. it would also be very thin. Ni barrier would stop the Au diffusion, but brings with it a whole new set of problems, among which are a thicker possibly equally brittle Ni layer, Black Pad with too muc P, Ni 'hyper-galvanic' corrosion with too little P, etc.> My question about your problem is—have you determined whether the Cu is not brittle itself. If you use un-annealed rolled Cu, it will be brittle in the cross-rolling direction.> > > > Werner> >>>**************>Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.> (http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001) --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------