Fellow techNetters, In the above IPC I did not see a correlation table of drill bit size to nominal external supported annular ring. Is there such a TABLE available anywhere. I do not have easy access to design guidelines/ground rules. I did review IPC-2221 section 9.1.2. By the way I concluded that SUPPORTED meant PLATED and UNSUPPORTED meant UNPLANTED. Was this a good assumption. Victor, --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------