When we've had a copper pour around microstrips the rule was that the clearance should be no less than the width of the transmission line. In your case, that is 10mils Min. -----Original Message----- From: Ray Dwyer [mailto:[log in to unmask]] Sent: Thursday, February 05, 2004 9:58 AM To: [log in to unmask] Subject: [DC] copper pour stand-off Greetings, I am concerned about rules for stand-off distance for copper pour on an outer layer to provide added isolation to a pair of sensitive low current traces. There are other traces on the top layer as well. The basic info is 50 ohm impedance, 10 mil wide microstrip, digital TTL signal current as low as in 10s of mili-amps, FR-4 material, 1 oz copper. Ray Dwyer 972-371-4046 Maxim 4401 Beltwood Parkway Dallas, Tx. 75244 --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------