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]

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