That may be the specified limit, but 1200 V/mm is one helluva gradient. I certainly would not tolerate such a gradient for high-impedance applications. I went as low as 25 V/mm when working at impedances of >1E12 ohms with FR-4. So, to plagiarise an outstanding contributor to this forum, I would say, "it depends". Brian McGlaughlin, Jeffrey A wrote: > Phil - > > IPC-2221 Table 6-1 covers electrical spacing column B1 applies to bare > boards internal traces. The calculated spacing for 600V would be 0.5mm > [0.020"]. > > > Jeffrey McGlaughlin, CID > Engineering Designer > Battelle > 505 King Avenue > Columbus Ohio 43201-2693 > (614)424-7582 Phone > (614)458-7582 Fax > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting > Sent: Monday, October 15, 2007 10:29 AM > To: [log in to unmask] > Subject: [TN] inner layer spacing for voltage > > Good morning, > > One of our engineers posed this question; > > " I have an inner ground plane in an area with high voltage (to 600 V). > My question is this: What is the recommended spacing between the > plated-though hole with this voltage and the internal ground plane > relief outline? I will go with 10 V/mil as a default, but I am hoping > the safe limit might be a bit higher than this." > > Can you point me to an IPC spec for this? I was thinking it might be in > 2222. > > Thanks in advance. > > Phil > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 847-615-7100 > ext.2815 > ----------------------------------------------------- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 847-615-7100 ext.2815 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 -----------------------------------------------------