Covers qualification and performance requirements for flexible printed boards designed to IPC-2221 and IPC-2223. The flexible printed board may be single-sided, double-sided, multilayer or rigid-flex multilayer. All of these constructions may include stiffeners, plated-through holes (PTH) and blind/buried vias. Revision B incorporates updated requirements for surface plating, measles, foreign inclusions, adhesive squeeze-out, solderable annular ring, PTH copper wrap, plating folds, microsection evaluations, acceptance testing frequency and more. Supersedes IPC-6013A with Amendment 2. For use with IPC-6011