Starr, The specification is IPC-D-275, Design Standard for Rigid Printed Boards and Rigid Printed Board Assemblies. The Section is 3.8.4.3, and it calls for 1.3 um [0.00005 in] minimum, 2.5 um [0.0001 in] maximum. Regards, Gary Ferrari IPC Staff *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************