Hi Paul, A good start for some background and 'Design for Reliability' information can made be looking at Appendix B of IPC-D-279, "Design Guidelines for Reliable Surface Mount Technology Printed Board Assemblies." If you need more information, I give a workshop "Design, Manufacturing and Reliability Issues of Small-Diameter/High-Aspect-RatioPlated-Through-Holes and Vias" ( just gave it at IPCWorks'97) it interested clients. 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] ############################################################## 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 ##############################################################