Flexible circuits, also known as flex circuits, FPC or flexible printed circuit boards (FPCBs), are electronic circuits that can be bent, twisted, and folded to fit into tight spaces and complex geometries. Unlike traditional rigid PCBs, flexible circuits use a flexible substrate material, such as polyimide or polyester film, to support the conductive traces and components. They are bendable to complete three-dimensional (3D) wiring that rigid circuit boards cannot achieve. The lightweight and thin profile contribute to space-saving designs. Additionally, flexible circuits exhibit enhanced durability, reliability, and the capability to withstand dynamic applications, making them crucial in the evolving landscape of electronic design. Because of this flexibility, flexible circuits have many advantages over other wiring methods and have many applications in electronic equipment that require high-density wiring in a small space. They are popular used in a wide range of electronic applications, including smartphones, tablets, wearable devices, medical devices, automotive electronics, aerospace and defense systems etc. Most flexible circuits have cabling functions rather than the mounting functions of electronic components.