Hi Dave,
Yes, I do think that inner layer foil cracks are more probable with1/2 oz
copper as compared to 1 oz, especially with Standard E1 foil which can be
shipped down to 2% elongation under IPC-MF-150. While foil with such lousy
ductility is not shipped very often, it does happen. And when it happens,
that foil also will have lower strength, higher etch rates, and higher
electrical resistivity.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 973-543-2747
E-mail: [log in to unmask]