Hi Myke,
You will also find, that your PTV barrel cracks are at locations within the
prepreg layers (higher resin content) closest to the MLB center (highest load
& thinnest Cu (dog-boning)=higest stress). Higher Tg resins will definitely
help, as will reduction in soldering temperatures, particularly manual
operations which are notorious for causing the most problems, and high-
temperature processing steps. also check the ductility of your plated copper;
note that the ductility of the copper in the hole is always lower than the
ductility of mandrel plated samples for electrolytic Cu.
For some more information, you should check Appendix B of IPC-D-279, Design
Guidelines for Reliable Surface Mount Technology Printed Board Assemblies.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]

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