Flex & Rigid-Flex circuits can be shaped to fit where no other design can.Flexible circuits (also variously referred to around the globe as flex circuits, flexible printed circuit boards, flex print, flexi-circuits) are members of electronic and interconnection family. They consist of a thin insulating polymer film having conductive circuit patterns affixed thereto and typically supplied with a thin polymer coating to protect the conductor circuits. The technology has been used for interconnecting electronic devices since the 1950s in one form or another. It is now one of the most important interconnection technologies in use for the manufacture of many of today's most advanced electronic products.In practice there are many different kinds of flexible circuits, including one metal layer, double sided, multilayer and rigid flex circuits. The circuits can be formed by etching metal foil cladding (normally of copper) from polymer bases, plating metal or printing of conductive inks among other processes. Flexible circuits may or may not have components attached. When components are attached, they are considered by some in the industry to be flexible electronic assemblies.Rigid-flex PCB is rigid part + flex part.usually,the material is FR4+PI.Most are multilayer board,but some single and double sided rigid-flex board as well.