A membrane switch is a printed electronic circuit that uses pressure to open and close a circuit. The membrane switch circuitry is most often screen printed using conductive inks, which are typically made of silver, carbon, and/or graphite.
Membrane switches are part of a range of devices considered to be user interfaces (also called operator interfaces, or man-machine interfaces) along with display-based touch screens, and mechanical switches such as push-button, toggle, rocker, and slide switches. The ultimate purpose of a membrane switch is to serve as the interface between man and machine, enabling an operator to communicate with a piece of equipment, instrument, or machinery.
Completely sealed surface – easily cleaned and sterilized
Low Profile – no crevices that can trap contaminants
A cost-effective alternative – less costly than rubber keypad assemblies and capacitive touch keypads
Thin profile – saves valuable space in your product design
Easy to interface with existing controllers – no special electronics required, as with touch screens
Versatile graphic interface – overlays can be screen or digitally printed with stunning, photo-quality graphic effects
Protection by design – Easier to protect from UV radiation than rubber keypads
Water-resistant designs – meets NEMA 4 and IP 67 specifications
Membrane switches are essentially a sandwich of thin layers that are bonded together using pressure sensitive adhesives. Depending on the application requirements, a membrane switch will consist of as few as 4, and as many as 9 layers. In contrast to mechanical switches, membrane switches offer the advantage of lower cost, they consume less design space with their low profile, are easy to clean, and they offer a sleeker, ergonomic, and aesthetically pleasing appearance.
The visible top layer of a membrane switch is the graphic overlay, with printed circuitry underneath the overlay. The circuitry can also incorporate different layers such as polyester, polycarbonate etc. Activation of a switch occurs when a printed shorting pad or metal dome makes contact with the bottom circuit layer thus, closing the circuit.