Rigid flex printed circuit boards are boards using a combination of flexible and rigid board technologies in an application. Most rigid flex boards consist of multiple layers of flexible circuit substrates attached to one or more rigid boards externally and/or internally, depending upon the design of the application. The flexible substrates are designed to be in a constant state of flex and are usually formed into the flexed curve during Flexible PCB manufacturer producing .

Rigid flex designs are more challenging than the design of a typical rigid board environment, as these boards are designed in a 3D space, which also offers greater spatial efficiency. By being able to design in three dimensions designers can twist, fold and roll the flexible board substrates to achieve their desired shape for the final application's package.