Castellated edges are semi-circular cutouts along the edge of a printed circuit board (PCB). These notches allow the PCB to be mounted and soldered directly onto another board, similar to how surface-mount components are attached. In cybersecurity hardware, castellated edges facilitate the integration of security modules or chips onto motherboards, enabling secure hardware upgrades or modular security features. This design ensures reliable electrical connections and simplifies the manufacturing process for devices requiring embedded security solutions.