Peter, To the best of my knowledge all boards designed by our CAD group use the same "standards" and in this case 0.015 is the spacing. The problems only show up on this one engineers boards and it doesn't seem to matter what the board layout or circuit application is. The Fab house is always the same. Sigh! Thanks, Phil -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Thursday, March 27, 2003 6:52 PM To: TechNet E-Mail Forum.; Phil Nutting Cc: [log in to unmask] Subject: Re: [TN] PTH clearance between pad and gnd plane Hi, Phil, OUr (CLass 3) boards were designed using IPC-2222 guidelines and our pad-to-copper fill area clearance is 0.015". So far we have not experienced any shorts with this clearance, so you should be OK. Do your shorts occur in the same places each time? Is the problem with one product from this engineer of yours or a number of them? Are the problems on every board of the type or just some? Are there any features in his design that don't appear in other designs because design rules haven't been followed - e.g. specified registration tolerances, drill positional tolerances, hole:pad diameter ratios, etc. Sounds like you may have either or both of two things - over-tight tolerances from your designer, or poor process control from your fab house. Do you use the same fab house for all your products? I had something of an issue with our technical director a couple of years ago when I received a number of "comments" from our fab houses that our tolerances were very tight. I discovered that the r.m.s. manufacturing tolerance allowance had not been included in the pad:hole diameter ratio, making it virtually impossible for the fabs to achieve my annular ring requirements. Director's excuse was that as they didn't know what tolerance any given fab house could work to, they didn't specify one at all in the mistaken belief that they were doing the right thing. Maybe you have a similar sort of a problem? Good luck Peter Phil Nutting <[log in to unmask]> 27/03/2003 10:38 PM Sent by: TechNet <[log in to unmask]> Please respond to "TechNet E-Mail Forum."; Please respond to Phil Nutting To: [log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Subject: [TN] PTH clearance between pad and gnd plane Good morning, We sometimes have a problem with PTH leads shorting to the ground plane. The curious thing is we use the same design and assembly methods for all our boards, but the problems only show up on one engineer's product. What is the "recommended" clearance between a pad and the adjacent ground plane? Ours look to be 0.015". TIA Phil Nutting --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------