A flexible circuit refers to one of the processes used to manufacture electronics. In electronic manufacturing, there are two primary types of electronic assemblies: the printed circuit boards and flexible circuit boards. Printed circuit boards are several layers of copper sheets laminated together to form a rigid platform for component wiring. A flexible circuit board is made of a layer of plastics like polymide film that can be run with electronic flexible circuits.
The primary difference is that printed circuit boards cannot be bent where flexible printed circuit boards can be flexed during use and not cause harm to the componentry. The most common uses for flexible printed circuits are in consumer applications such as cameras and cell phones.
Cameras are being built in smaller and smaller packages. The consumer wants a camera that is lightweight and easy to carry in a purse or pocket. By using printed flexible circuits, the manufacturer is able to achieve a very small package that continues to have more features, such as additional memory and video capability.
Cell phones also use a flexible circuit to accomplish a smaller package to meet consumer demand. Known as dynamic application, the flexible printed circuit board in a cell phone is actually folded with every use in the flip phone variety. The circuit runs the entire length of the phone and when in use is open so the person can dial and talk. When the call ends and the phone is not in use, the flexible circuit is folded close inside the phone's case.
Printed flexible circuit boards also have uses in industrial applications. Since a flexible circuit does not require the many layers like a printed circuit board, it can be used in places where there is not sufficient clearance to fit a printed circuit board. Some of the most common uses for the narrow flexible circuits is in solar cells for satellites.
Solar cells are used to capture sunlight and convert it to energy. This type of energy conversion, known as photovoltaics, requires lightweight materials that can be used for power in satellites. The flexible circuits are ideal for this application because they can be formed to whatever shape is needed and folded and stored when not in use. This is especially helpful on manned spaceflights where space is at a premium but a significant amount of energy is needed to support the crew's activities.