The newest IPC solder mask specification is the IPC-SM-840C. This spec breaks the solder masks into two classes:\ A. Class "T" - Similar to the Bellcore TSY-000078 specification B. Class "H" - Similar to the MIL-P-55110D military spec Class "T" is similar to the old class 2 of the IPC-SM-840B spec which covered masks for computer, telecommunications, instruments, etc type applications. Class "H" is similar to the old class 3 wich covered masks for high reliability and military type applications. Hope this helps. For more info, please call me. Larry Fisher Dexter Electronic Materials Phone: (317)-628-7401 [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. * *************************************************************************** * 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] * ***************************************************************************