Rigid-flex PCBs represent a cutting-edge technology that seamlessly integrates both rigid and flexible substrates within a single board. This innovation allows designers to create three-dimensional electronic circuits, offering enhanced flexibility and durability compared to traditional rigid PCBs. The rigid sections provide stability and support for components, while the flexible sections enable bending and folding, making them ideal for applications with space constraints or intricate designs. 

The principal applications of rigid-flex PCBs are aerospace and military electronics where weight and reliability are major concerns. Nowadays with the rapid development of electronic packaging, Rigid-flex printed circuit boards have gained wide use in various electronic devices and equipment, particularly in industries like consumer electronics, medical devices, and automotive systems. The ability to design custom shapes and optimize spatial efficiency has spurred their adoption in wearable technology and IoT devices. However, transitioning to rigid-flex PCBs poses challenges, including intricate manufacturing processes, increased complexity in design, and higher production costs.