Are you sure that the PTV walls have not pulled away from the drilled epoxy
thru hole walls prior to your cycling as the result of the soldering
processes? The cracking of the copper barrel walls point in that direction
also.  As pointed out by David Arivett, plating thickness is not necessarily
equal to copper quality; it can be uniformly thick, but still have low
ductility. Also I suspect that the Hysol SR 1000 has a large thermal
expansion coefficient, squeezes out of the PTV at 150C and on cooling there
not enough Hysol left to fill the hole so it looks like it is shrinking.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-mail: [log in to unmask]

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************