Regarding annular ring: The main reason for annular ring in the original printe board specs was to provide a space for the solder to filet between the teminal or eyelet and the land. All of the current IPC specs., IPC-RB-276 and IPC-6012 allow breakouts in the Class 2 (90 degree) and Class 1 (180 degree). Many tests have been run to determine if breakout was a real or cosmetic defect. Several that I am aware of showed that an annular ring circumscribing the hole had no effect long term life or reliability. However, until the past few years when more circuitry in less space became a necessity, some of us die-hards said that we like the totally circumscribng annular ring. No one seems to know if tangency, 1 mil, 2 mils or 5 mils if better, one test that I heard about said that there was no significant difference. The majority of circuit board product unless it is Military spec. has a 90 degree breakout acceptable. There is a test program that was done by ITRI on "landless holes" and the data is presently or soon to be available. We hope to be reviewing this data with possibility of incorporating it in IPC-6012 at the Rigid Board Performance Task Group meeting in San Jose. Meeting is Sun Mar 9th. Phil Hinton *************************************************************************** * 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. * *************************************************************************** * 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] * ***************************************************************************