Rigid-flex PCBs combine the best of rigid and flexible circuit boards, integrating rigid sections (for component mounting) with flexible segments (for connectivity between rigid parts) in a single, seamless structure. This hybrid design eliminates the need for connectors or cables, reducing assembly complexity, weight, and failure points—making them ideal for compact, high-reliability devices like aerospace equipment, medical implants, and military electronics.

The construction of rigid-flex PCBs involves alternating layers of rigid substrates (typically FR-4) and flexible materials (polyimide). The flexible segments act as hinges, allowing the board to bend or fold into 3D shapes, while rigid sections provide stability for mounting components such as microchips, resistors, and connectors. Copper traces span both rigid and flexible areas, ensuring continuous electrical connectivity across the entire board.

Manufacturing requires precise alignment of layers during lamination to prevent delamination, especially at the interfaces between rigid and flexible sections. The flexible portions are often reinforced with polyimide cover layers to resist wear during bending, while the rigid sections may use thicker copper (2–4 oz) to handle higher currents. Multi-layer rigid-flex designs can include blind or buried vias to connect layers without compromising flexibility.

Applications benefit from the board’s ability to fit into tight spaces: for example, in a satellite, a rigid-flex PCB can fold into a compact launch configuration and then unfold in orbit to connect various subsystems. In medical devices like pacemakers, the flexible segments adapt to body movements without stressing connections. Testing includes thermal cycling (-55°C to 125°C), vibration resistance, and flex testing to validate performance in dynamic environments. Rigid-flex PCBs thus offer a versatile solution for complex, space-constrained electronic systems.