Rigid Printed Circuit Board. We all know that a PCB can be Single Sided PCB, Double Sided PCB or Multilayer PCB. At the same time a PCB can be Rigid, Flexible or Rigid-Flex (Combination or Rigid and Flexible PCB). Rigid PCB is Solid, inflexible Printed Circuit Board. So, Rigid Circuit Board is a PCB that we cannot bend or force out of shape.