I have had exactly that conversation with suppliers of direct plate chemistries: If a large nailhead is present, then part of it can be removed after microetch, which is done AFTER key steps in the process. Microetch is done after the application of the carbon/graphite in the Blackhole/ Shadow processes, & after the wetting agent conditioner in the palladium systems. These can leave circumferential voids. The recommendation was to perform a microetch before the key steps if a Fab shop knows that it has nailheading. MB ______________________________ Reply Separator _________________________________ Subject: Fab-Re: More nailheading Author: [log in to unmask] at SMTPLINK-HADCO Date: 5/2/96 05:07 PM Other info on nailheading Received a note on nailheading to the effect: What if a direct-plate process was used and the undercutting that is required to remove the unwanted coating also etched away the thin layer of copper at the extension of the nailhead. Does this result in a circumferential void?. I believe it would; however, it probably does not have have any relation to the often specified 150% of the base foil thickness, and may also happen with a 125% nailhead. Other incidental on nailheading: It is remembered that Bob Lomerson-ex Gen Dynam-Ft. Worth has a patent on a nail heading process wherein he imposed on the top of the drill stack during drilling a layer of another foil and nailheaded (smeared) it all the way through the the hole thus eliminating electroless processing. Phil Hinton hintpwb1.aol.com