But what I read says that given two needle points at sea level in dry air the maximum is about 46V/mil (Handbook of Chemistry and Physics, or "CRC"). Two conductors on a circuit board can sometimes form something closely resembling needle points. Now add some moisture, altitude, dust, defects in your solder mask and my personal experience and your rule of thumb becomes 5V/mil!!!!!! Have fun, Ahne Oosterhof A-Laser, Inc. (503)641-9428 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Dave Hoover Sent: Monday, August 09, 1999 8:23 AM To: [log in to unmask] Subject: Re: [TN] High Voltage test -1.2kV AC on PCB Everything I've read says 50 Volts per mil (.00002" X volts) . If it's an outerlayer, you should make sure your supplier can double coat soldermask because you need as much insulation you can get there. Air tends to be a great conductor especially with certain temp and humidity. Dave Hoover -----Original Message----- From: Anil Kher [mailto:[log in to unmask]] Sent: Friday, August 06, 1999 8:44 PM To: [log in to unmask] Subject: [TN] High Voltage test -1.2kV AC on PCB I need to hold 1.2kV across tracks - covered with Solder resist masking. Operating temp. 20-35deg C and RH upto 99 %. PCB matl. is FR-4 1.0mm DS. Could you advise me as to the minimum gap to be kept between the tracks ( they run close to each other for 30 mms) Could somebody help me with arcing distance for 1.2 kV in 95% RH conditions. Thanks Anil Kher ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################