Hi 'pete,'
In answer to your questions.
1. Yes, cross-head speed will affect alongation—the higher the speed the
lower the elongation.
2. For the same material, if you anneal it, elongation will increase and
strength will decrease.
3. This pre-bake has some annealing capability, but also is designed to
eliminate plating stresses of the foil samples plated onto and peeled from
stainless steel mandrels.
Having said this, elongation values will also vary with foil thickness for
the same material; and sample preparation is critical.
2.4.18.1A is a decent test method for process control with the point being
that the test is performed the same way by the same laboratory on essentially
identical specimens. It is not designed to give good physical properties. It
does a good job with tensile strength, but a "tensile test" is a lousy test to
determine the ductility of foil specimens. For foil specimens, only elastic
strains are measured and the whole plastic deformation regime is neglected. That
is why IPC TM-2.4.2.1 "Flexural Fatigue and Ductility, Foil,” was developed.
Regards,
Werner Engelmaier, former chaiman of the IPC Copper Foil Committee
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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