What is rigid flex pcb board?

Rigid-flex PCB board, it is a circuit board that combines flexible and rigid circuit board technology in the application. Most rigid-flex boards are composed of multiple layers of flexible circuit boards, which are attached to one or more rigid boards from the outside and/or from the inside, depending on the design of the application. The flexible substrate is designed to be in a constant deflection state, and is usually formed as a deflection curve during rigid flex pcb manufacturing or assembly.

https://hitechcircuits.com/pcb....-products/rigid-flex

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