When researching the different types of electrical switches, you’ll probably come across membrane switches. Featuring a flexible and elastic construction for at least one of the two contacts, they’ve become a popular alternative to traditional switches. With that said, you may have some questions about membrane switches and how they work.
#1) Do They Feature Circuits?
Like all electrical switches, including mechanical switches, membrane switches feature a circuit. The circuit used in membrane switches, however, is printed on either PET or ITO using electrically conductive ink. The use of conductive ink essentially turns the circuit board into an electrical contact.
#2) How Do They Work?
Membrane switches work by completing or breaking the circuit when pressed. They contain two contacts: One is underneath the button while the other is on the printed circuit board. When the button is pressed, the two contacts will meet to open or close the circuit.
#3) Do They Produce Tactile Feedback?
Some types of membrane switches are designed to produce tactile feedback when pressed. Known tactile membrane keypads, They typically snap or “pop” back after being pressed. It’s a subtle force, but it’s enough to help reduce typing and input errors.
#4) How Many Layers Are They Made of?
Membrane switches are made of multiple layers. Although there are exceptions, most contain a membrane overlay layer, followed by a spacer layer, a printed circuit layer and back layer. The overlay layer, of course, is the layer on which the button’s keys or legends are printed. Below this layer is the space layer filled with air or inert gas. Pressing the button causes the top contact to push below the space layer where it touches the underlying printed circuit layer to complete the circuit.
#5) Do They Support Backlighting?
All types of membrane switches support backlighting. Backlighting is used to illuminate the switch’s keys from underneath. There are several different backlighting solutions available for membrane switches. Light-emitting diodes (LEDs) offer a highly effective, as well as efficient, backlighting solution for membrane switches. In addition to LEDs, other types of backlighting supported by membrane switches include light guides, optical fiber and electroluminescent (EL).
#6) What Industries Use Them?
You can find membrane switches used in a wide range of industries. In the medical industry, for instance, they are frequently used on health-monitoring machines. In the aerospace industry, they are used on cockpit control interfaces. In the retail industry, membrane switches are used on point-of-sale (POS) systems.