Hi Ken, In addition to what Ray Klein and Jerry Cupples have said, solid power and ground planes without thermal relief spokes, will stress the PTH/PTV copper barrels more than spoked planes or signal layers during the large z-direction thermal expansion differences caused by soldering processes. PWBs with PTH/PTV qualities on the hairy edge for the construction and processing sequence may show barrel failures in the prepreglayer-are ajacent to the solid Cu-plane. 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] ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################