On an allied question to the one on inner layer for voltage what is the minimum drilled hole to copper inner layer clearance? I have an engineer wanting 6 mil drill to copper nominal which would, allowing for a 2 mil drilling tolerance give 4 mil drill to copper on the internal layer. I might be off track but to me that is too close even though the voltage is a few volts (crazing, wicking issues etc). What are experiences on this type of high density close drill to copper clearance especially with lead free process temperatures? Inputs gratefully received, John John Burke (408) 515 4992 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 -----------------------------------------------------