Your comment about how you have days without any shorts, then start observing them might lead you to look at your etchant process, chemical condition, line speed, etc etc... ...something to consider, could those days you begin seeing shorts possibly correlate to just before the etchant was replenished? replaced? or otherwise have maintenance performed? Aside from etch related conditions, drill or layer mis-registration in my experience, is the second most likely cause of such unusual occuring shorts Franklin --------------------------------------------------- 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 -----------------------------------------------------