Interesting, you dare use FR-4 for such voltage (and perhaps high current possibility)? We use Teflon and other materials (that absorb little water) when doing with such levels. Thought wall thickness wasn't most important, but creep distance across. Regards Ingemar Hernefjord Ericsson Microwave Systems -----Original Message----- From: Ted J. Casper [mailto:[log in to unmask]] Sent: den 26 juni 2002 15:13 To: [log in to unmask] Subject: [TN] Voltage Breakdown of Thick Laminates I am looking for help in determining how to specify the thickness of a layer that must handle 7kV. For discussion purposes lets say the material is FR4 with a dielectric strength of 750V/mil. (NOTE: mil=0.001 inches) I also realize that this dielectric strength number is thickness dependent. For other types of insulators I have used a square root relationship to calculate actual voltage breakdown. For instance: If I have a piece of Teflon with a dielectric strength of 1000V per mil measured at 5mil, the breakdown for a 20mil thick piece would be approximately 1000V/mil * 20mil /[(20mil/5mil)^.5] = 10000V. Now for my questions: 1) Is there a standard thickness that is used to test dielectric strength of PCB materials? 2) Does the square root of thickness function apply to PCB material? 3) If not, how would I estimate how much voltage could be applied from one side to the opposite of a 20mil thick laminate (FR-4)? I have been reading the postings for voltage breakdown and dielectric strength that are in these forums. One posting (actually written in two parts) by Ralph Hersey was very interesting but cautioned about using thin single sheet laminates. Does this caution apply to thicker laminates? Thank you! Ted Casper LECO Corporation Phone 262-338-2191 e-mail: [log in to unmask] --------------------------------------------------------------------------------- Technet 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 Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet 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 Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------