A PCB electromagnetic relay is an electromechanical switch mounted directly onto a printed circuit board. It consists of an electromagnetic coil, a set of contacts, and a movable armature. When an electric current passes through the coil, it creates a magnetic field that causes the armature to move, thereby opening or closing the contacts. These switches are used for controlling a circuit’s power by turning on or off electrical devices in response to a control signal. The compact design of PCB relays allows them to be easily integrated into various electronic devices, making them ideal for space-constrained applications.