HI Jeffry but you can manufacture much better line resoultion then 15 mils in 3 oz of plated copper , using the method I stated even 3/3 is possible, through my research we found thick dry film up to 20 mils, produced almost as good a line resolution as thin 1.5 mil dry film did, in fact I made many boards for IBM with 20 oz of plated copper at 10/10 technology. we started with thin base copper and in fact did not use a tin protective layer but just a quick etch as the 1/8 oz base copper etched very quickly with no damage to the plated copper. The exposure and developing is not tricky but does require a bit of the "out of the box" additude. robert Tarzwell megadawn.com --------------------------------------------------- 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 -----------------------------------------------------