Switches typically require a top layer. Known as an overlay, it often contains conductive contacts on the underside. Pressing a button on a switch will force these conductive contacts to touch a lower set of conductive contacts, thus completing the circuit.
While you can find switches in different styles, most of them have one of two types of overlays: panel or membrane. Panel and membrane overlays are both top layers, and they serve the same purpose of providing conductive contacts for the circuits. With that said, panel and membrane overlays feature different designs.
What Is a Panel Overlay?
A panel overlay is a type of switch overlay that features a traditional design with a mechanical method of operation. You can find them in different materials. Some panel overlays are made of hard plastic, whereas others are made of metal. Regardless, panel overlays serve as the top layer for a switch. It features the buttons for the switch’s keys that, when pressed, will open or close the circuit.
What Is a Membrane Overlay?
A membrane overlay is a type of switch overlay that essentially wraps around the circuit or circuits with which it’s used. They are separate layers. Like panel overlays, membrane overlays are available in different materials. Some of the most common materials for membrane overlays include polyester and plastic. Polyester is often preferred because of its natural resistance to solvents. Polyester can withstand solvents — as well as other chemicals — without degrading.
Differences Between Panel and Membrane Overlays
While they both serve as the top layer for a given switch, panel and membrane overlays aren’t the same. Membrane overlays are always separate layers, whereas panel overlays may or may not be separate layers.
You typically won’t find panel overlays in polyester. Rather, panel overlays are usually made of plastic. In comparison, membrane overlays are available in both plastic and polyester. Polyester is the preferred choice of material for membrane overlays because of its solvent- and chemical-resistant properties.
Membrane overlays support embossing. Embossing, in fact, is commonly used to create tactile feedback. The surface of a membrane overlay can be embossed so that it provides a physical sensation when pressed. Known as tactile feedback, this physical sensation can improve input accuracy.
You’ll have multiple backlighting options to choose from when buying a membrane overlay. They support several types of backlighting, including light-emitting diode (LED), electroluminescent (EL) and fiber optics. Backlighting leverages another layer that’s printed behind the membrane overlay.