IPC-2223E used in conjunction with IPC-2221, IPC-2223 establishes the specific requirements for the design of flexible printed boards and forms of component mounting and interconnecting structures. The flexible materials used in the structures are comprised of insulating films, reinforced and/or non-reinforced dielectric in combination with metallic materials. IPC-2223E provides new design guidance and requirements for fabrication drawings, hole to edge spacing, bend area conductor considerations, dielectric thickness between rigid and flexible regions and dual row zero insertion force (ZIF) connectors.