Membrane switches have become an increasingly popular electrical switching solution. Even if you’re unfamiliar with them, you’ve probably seen or used a membrane switch. A common example is the buttons on a typical microwave. The buttons have a low profile and made of a flexible material. As a result, they are considered a type of membrane switch. In this post, we’re going to take a closer look at the construction of membrane switches, revealing how they differ from conventional switches as well as the process by which they are manufactured.
What Is a Membrane Switch?
A membrane switch is a type of electrical switch that’s characterized by the presence of at least one conductive contact made of a flexible material. Unlike with mechanical switches, membrane switches aren’t made of copper or plastic. Rather, they use conductive ink to create the contacts. With the ink consisting of copper, silver or graphite, it’s able to conduct electricity, which is the basis on which membrane switches work.
How Membrane Switches Are Made: What You Should Know
Different membrane switches are made using different techniques. With that said, most membrane switches consist of a few basic layers. The uppermost layer, known as the membrane overlay, is found at the top of a membrane switch. Below the membrane overlay is a spacer layer, which as the name suggests, is simply intended to create space. Below the spacer layer is the printed circuit layer. Also known as a printed circuit board (PCB), the printed circuit layer consists of conductive ink on a circuit board.
Below the printed circuit layer is the rear adhesive layer, which consists of adhesive used to bind the membrane switch’s components and hold them together. Finally, below the rear adhesive layer is the tail filler layer, which consists of filler materials to fill the empty remaining space.
What About Backlighting?
In addition to the aforementioned layers, it’s not uncommon for membrane switches to feature backlighting. Backlighting for membrane switches is achieved using one of several options, including light-emitting diode (LED) light guides, fiber optics or electroluminescent (EL). Of those options, LED is often preferred because it offers the highest level of energy efficiency, meaning it lasts longer than other types of backlighting.
Membrane switches are typically designed using five layers. This includes the overlay layer, the spacer layer, the printed circuit layer, the adhesive layer and the tail filler. When combined, the end result is a superior switching solution that can be used in a variety of commercial and consumer applications.