Bob Vanech The statement in IPC-D-275 requiring 0.001 annular ring is for design purposes. You always design to have an annular ring, you do not design for breakout. IPC-RB-276 accepts no breakout for Class 3, but allows a 90 degree breakout for Class 2 and a 180 degree breakout for Class 1. This is the manufacturing acceptance criteria which allows some "not entirely perfection" in the board for some Classes. If you read the same paragraph in the forthcoming issue of the replacement for IPC-D-275 which is IPC-2221 you will find words to the effect that the annular ring number is for desig calculation and that the performance specifications may allow breakouts for some classes. Phil Hinton Hinton "PWB" Engineering [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************