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
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