Jong, The amount of time the PCB will see 20-30 amps plays a role in copper used and trace size. If the board will see this current all of the time, FR4 will probally not handle it. We are currntly running a 25 amp power board using 2oz. copper on outer layers that is plated up to 3oz. and then tin-lead reflowed. The trace size is a minimum of .325". This PCB only switches 25 amps on for about 10 seconds at a time. Check out www.ultracad.com for a trace width calculator based on IPC-D-275 charts and also an article Mr. Brooks wrote on "melting traces". Best of luck! -----Original Message----- From: jong s kadesch [mailto:[log in to unmask]] Sent: Thursday, February 17, 2000 11:34 AM To: [log in to unmask] Subject: [TN] copper weight Hi Technetters, What is the max. copper weight I can get on the outer layers of the board with the current of 20 to 30A? I'm fairly new to with high current board. Thanks in advance. Jong Kadesch ############################################################## 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 ############################################################## ############################################################## 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 ##############################################################