What is a membrane switch and how does it work?
Learn more about this versatile user interface.
Nelson Miller Group has been a leading membrane switch manufacturer since the technology was commercialized in the 1980s. Membrane switches are user interfaces (also called operator interfaces or human machine interfaces). By pressing a button on an overlay, the operator can achieve a desired effect in a piece of equipment, instrument, or machinery.
Membrane switches are used in a variety of domestic, commercial, and industrial applications. They're preferred to purely mechanical switches because of their compact profile, simple construction, reliability, resistance to harmful elements, and low cost. Unlike mechanical switches, which are generally constructed with copper and plastics, membrane switches are composed of several thin, flexible layers, including printed circuits on film.
The different layers of a membrane switch
A membrane switch is an electrical switch assembly that uses contact or pressure to open or close a circuit. They're constructed from several layers of flexible materials that can be customized to fit your specific design and operating characteristics. However, no matter the design or function, there are a few primary components that can be found in all membrane switches:
Graphic overlay
The overlay is the top layer of the membrane switch. This is the layer that shows the operator what they're pressing.
The graphic overlay is the exposed part of the switch and is made from materials that have excellent flexibility, clarity, toughness. Manufacturing processes use digital print, screen-print, or a combination of both to ensure the right colors, textures, and finishes.
Spacer
This layer separates the top circuit from the bottom circuit, so the switch remains open until the keypad is pressed. The spacer ensures that the circuit isn't activated without intent-the button only registers when it is intentionally pressed.
Circuit
The circuit is what makes a membrane switch operational and controls the electronic device. They're printed with conductive inks and may use some dielectric inks to protect the circuitry. This bottom circuit layer terminates as a flexible tail that serves as the interconnect to controller PCBs or other electronics.
Adhesives
Adhesives are crucial since they attach the entire assembly to the end product and bond the graphic overlay layer to the circuit layer.
