What Are Multilayer PCBs? Multilayer PCBs contain three or more copper conductive layers — usually with plated through holes. If a board is constructed with both flexible and rigid materials, it’s known as a rigid-flex PCB. A rigid-flex circuit board is a 3D interconnect that can be bent and folded into almost any shape. Rigid-flex technology allows designers to replace multiple PCBs... https://www.pcbhamal.com/what-are-the-advantages-of-multilayer-pcb/