A padless PTH is not a blind via unless it is closed off at one end; than it would be unplateable in an .093" PWB. Occlusion of either PTH opening would indeed result in mass transport limited plating were the Cu ions in inadequately replenished. The quality of the copper deposit would suffer in terms of greatly diminished physical properties (strength, ductility) and plating thickness uniformity (dog-boning) with reduced reliability consequences. A padless PTH may require for processing reasons a small pad of a size dictated by the registration accuracy. A padless PTH by definition has a rim void on the padless side and therefor there is no weak 'knee' or shoulder; without any connections on the O/L that is of no concern. I would not recommend reducing the PTH diameter; smaller diameter PTHs have lower reliability (see IPC-TR-579). 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. * ***************************************************************************