Hi Arnaud, Along with what Werner mentioned, have you checked into using a fatigue ductility tester? In a previous company that I worked for during the late 80's, we had flex circuit failures on a multi-chip unit assembly. I assisted some folks with testing RA copper using a ductility tester (if memory serves) from Universal. I think if you search the web, some of these testers may still be available, and can be used as an additional data point to test your copper. Again as Werner mentioned, proper metallurgical x-sects of the Cu should also be done. Regards, Garry Morand Symmetrix Hardware Engineering EMC2 176 South Street Hopkinton, MA 01748-9103 ' 508-249-4329 * mailto:[log in to unmask] Pager: 888-377-9799 or mailto:[log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier Sent: Wednesday, November 09, 2005 7:14 AM To: [log in to unmask] Subject: Re: [TN] Copper Ductility Characterization - UPDATE Hi Arnaud, You do not give much of a description of your flex circuit. Thickness? Layer count? History? Bookbinder folds? Are you sure you have RA copper? It may be rolled, but not annealed and thus have high ductility in one direction and not the other. One way to determine that is to do an X-section--long needle-like grains are an indication opf insufficient annealing. Are there any unassembled circuits left? You could used IPC TM 2.4.3.2 "Flexural Fatigue and Ductility, Flexible Metal-Clad Dielectrics." Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- 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 -----------------------------------------------------