Al,

The IPC-RB-276 is a performance specification similar to the Mil-P-55110,
that the military uses. It is a sister document to the design standard,
IPC-D-275. The designer designs to IPC-D-275 which invokes manufacturing
provisions. The IPC-RB-276 is the standard that the fabricator uses to make
the board, in accordance with the design features of IPC-D-275. It tells the
fabricator what the acceptable defect levels are, for eachg of the provisions
of IPC-D-275. As designers, we live in a perfect world of nominals. In
actuality, there is a tolerance of manufacture associated with every step
ofthe process.

The reason that the standard is referenced, is to inform the designer of how
some things are measured, such as laminate thickness, annular ring, etc.

The IPC-T-50 is the terms and definitions document. It has been around for
quite a number of years. It was adopted by the government moons ago. It has
been translated and renumbered as IEC-194, for international use, under the
IEC.

Regards,

Gary Ferrari
Tech Circuits