Impedance-controlled FPC is a special type of flexible printed circuit board (FPC) that achieves impedance differential through a layered method, thus meeting needs of specific circuit specifications control. This type of circuit board is widely used in high-speed data transmission, high-frequency applications, medical, industrial, military, and other fields The main function of impedance-controlled FPC is to precisely control circuit specifications to ensure that the circuit can operate stably and efficiently. Its features include flexibility, thinness, miniization, and other advantages, making it suitable for space-constrained occasions, such as medical devices and handheld devices.