A membrane switch is an electrical switch for turning a circuit on and off. It differs from a mechanical switch, which is usually made of copper and plastic parts: a membrane switch is a circuit printed on PET or ITO. The ink used for screen printing is usually copper / silver / graphite filled and therefore conductive.
Membrane switches are user-equipment interface utilities that allow for the communication of commands from users to electronic devices. Membrane switches can be thought of as one category of interface utilities alongside touch screens, plastic keyboards, toggle switches and many other kinds of control systems. Interface utilities can be as simple as tactile switches for controlling lighting, and they can be as complicated as membrane keyboards and switch panels for use with computers.
Construction
A membrane switch typically has 4 or more layers. The top layer of a membrane switch is the graphic interface between the user and the machine. The another critical layer is a printed circuit. This can also be a flex circuit made of copper and polyimide material. The layers are normally assembled using pressure-sensitive adhesives although inexpensive designs can be held together by other mechanical means such as a keyboard housing. Contact between two traces can be made through a printed shorting pad or through a metal dome that stands on legs.
Application
Classic applications of membrane switches include microwave oven panel, air conditioner control panel, TV remote control etc. Tactile feedback of keys can be provided by embossing the top PET layer or embedding metal snap domes, polyester domes or forming the graphic layer.
The benefits of membrane switches include ease of cleaning, sealing ability and their low profile. Membrane switch can be used together with other control systems such as touch screens, keyboards, lighting, and they can also be complicated like the membrane keyboards and switch panels in mobiles and computers. They are reliable, effective, low-cost user interfaces, suitable for a wide range of products, and available with many creative options.
Depending on industry and application, membrane switches are also referred to as membrane keyboards and membrane keypads.