Flexible circuit boards combine elements from both flexible and rigid circuit boards, resulting in a board that can be folded or continuously flexed and is typically shaped into a flexed shape or curve during the manufacturing process.
Rigid PCBs are composed of multiple layers including a substrate layer, a copper layer, a solder mask layer, and a silk screen layer which are adhered together with adhesive and heat.
Rigid-Flex PCBs are designed in a 'sandwich' fashion, with several double-sided conductive layers divided by an equal number of insulating material sheets.