When shopping for membrane switches, you may come across some otherwise unfamiliar terms. Membrane switches are electrical switches that, like other switches, control a circuit. The difference is that traditional switches are made of a rigid material, whereas membrane switches feature at least one contact that’s made of a flexible material. Here are some common terms associated with membrane switches defined.
The overlay is the top layer of a membrane switch. Membrane switches are made of several layers. The uppermost layer is the overlay. It features the graphics that represent the membrane switch’s button or buttons . To use a membrane switch, you’ll need to press the overlay.
The spacer is exactly what it sounds like: a layer that creates space. It’s located directly underneath the overlay. With the spacer present, the overlay’s contacts won’t touch the contacts on the circuit board — at least not by default. You’ll have to press a button on the overlay to push down the overlay into the circuit board. The space is essentially what separates the overlay from the circuit board.
Printed Circuit Board
Also known simply as a printed circuit, a printed circuit board is an electronic circuit that’s made with etched conductive paths. All circuit boards have conductive paths. Conductive paths, of course, dictate the direction in which electricity travels. For printed circuit boards, these conductive paths are etched into an insulating sheet.
You may discover that some membrane switches have a Kapton circuit. A Kapton circuit is a special type of circuit that’s made of polyimide and copper. Kapton circuits typically offer a higher level of durability. They can withstand harsh environmental conditions without degrading. If you’re looking for a new membrane switch to use outdoors, you may want to choose one with a Kapton circuit.
Many membrane switches feature backlighting. Backlighting is a lighting system that’s installed in the rear of a given device. In membrane switches, backlighting will illuminate the legends or icons on the overlay. Backlighting isn’t limited to membrane switches, however. From touchscreens and TVs to keyboards and more, many devices support backlighting.
Light guides are foils that are used to distribute light. They are designed to distribute the light of a backlighting system. Backlighting systems produce light. Light guides will then pick up and deliver this light throughout the membrane switch. With light guides, membrane switches benefit from even lighting without succumbing to dark or bright spots.