High Quality Polyimide Material Flexible PCB Double Layer Flex PCB FPC ♦ What is Flexible PCB Flexible PCB (FPC) , also called a "soft board" or flexible circuit , is a type of printed circuit board (PCB) made from flexible insulating materials , such as polyimide (PI) or polyester (PET) , instead of rigid fiberglass (FR4). This unique construction allows FPCs to bend, fold, and twist without breaking, enabling compact, lightweight,