Flexible circuit boards (FPCs) are bendable PCBs commonly used in flip phones and battery protection circuits. They typically use polyimide for the base material and cover layer, with copper foil pressed together. The thickness is indicated by the copper foil weight (e.g., 1.5oz or 2.0oz). Unlike regular PCBs, FPCs have smaller cover layer openings over the copper foil, and resin bonding may cause solder issues if excessive. Cutting FPCs along contours with Micro Joints prevents burrs and warping during SMT processes, crucially maintaining flatness using supports like tape and synthetic materials.