Membrane Switch Construction
The ASTM defines a membrane switch as "a momentary switch device in which at least one contact is on, or made of, a flexible substrate."
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.
Membrane Switch Applications
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.
Depending on industry and application, membrane switches are also referred to as membrane keyboards and membrane keypads.