As a PCB expert, understanding the importance of designing flexible PCBs with the ability to bend is crucial, with factors such as bending radius, lamination structure, substrate thickness, number of layers, and covering material flexibility all impacting the overall functionality and durability of the circuit board. Calculating the bending radius can be done using standard guidelines or formulas, with the minimum bending radius typically between 1mm and 6mm for single-layer and double-layer flexible PCBs to ensure reliable dynamic bending stress.