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, PTHs, microvias, and blind/buried vias. Revision C incorporates new and updated requirements for final finishes, surface and hole plating, stiffeners, copper filled microvias, cap plating of holes, thermal stress testing, smear removal, and conductor thickness. Supersedes IPC-6013B. For use with IPC-6011. 50 pages. Released November 2013.