The question is one of what the shop would like to see, as all solder mask requires some clearance, the PCB shop will have to determen the actuall pull back based on there method of appling solder mask, for shops that use slik screening they need at least .008 clearance both sides. for shops using photo imagable they can get closer at .002-.003 each side. But it all depends on the type of board, if its flex thaen we need more because it moves more in processing and is hard to align. for longer boards the growth is enough to give aligmnet problems at even .008 spacing. If a board shop gets a file with no clerance it has to use its software and change the size of the solder mask openings ( pads reversed)to get the desired spacing, if you supply a over size pad opening with out consulting the shop then they may have to change it to make the board. if there is no tolerance then you will get solder mask on the pads which is a major problem in assembily. Remenber when we make a printed circuit board everything is moving around, the best we can work to is about +-.003 to +-.004 tolerance any where to any thing. hope that helps robert Tarzwell Megadawn.com ,pcb books --------------------------------------------------- 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 -----------------------------------------------------