hi, could you possibly mean permittivity rather that permeability? permittivity is commonly known as dielectric constant. i would expect permeability to be meaningless with fr-4; it isn't ferromagnetic. phil -----Original Message----- From: Barbara Burcham [mailto:[log in to unmask]] Sent: Friday, May 12, 2000 11:09 AM To: [log in to unmask] Subject: [TN] Fr4 Board materials have a permeability of? I was unclear when I asked this question, earlier. Can anyone tell me how to find the permability of the FR4 family of board materials in relationship to frequency? Barbara Burcham ############################################################## 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 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 1.8c ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################