From computers and TVs to calculators, appliances and more, switches are found in all types of electronics. A switch is nothing more than a circuit-controlling device. You can activate a switch to open or close a circuit. Some switches, however, feature an electrical contact that’s either made of or connected to a flexible substrate. Known as membrane switches, they are constructed of multiple layers. For a better understanding of membrane switches, keep reading.
Membrane Switches Defined
A switch is considered a membrane switch if one or more of its electrical contacts are made of or connected to a flexible substrate. Like all switches, membrane switches feature electrical contacts. Electrical contacts are conductive surfaces. Each circuit typically has two electrical contacts. The circuit will close when the two electrical contacts touch each other, and the circuit will open when the electrical contacts separate from each other.
You can find membrane switches in different styles, but they all have a flexible substrate. Membrane switches are made of multiple layers. The layers are stacked together, and they are joined using adhesive and pressure. The defining characteristic of membrane switches, though, is their flexible substrate. All membrane switches feature one or more electrical contacts made of or connected to a flexible substrate.
Membrane Switch Layers Explained
What are the different layers used in a membrane switch’s construction exactly? Most membrane switches feature several thin layers. The top layer is the membrane overlay consisting of the legends and buttons that, when pressed, will control the circuit or circuits. Below the membrane overlay layer is a spacer layer. As the name suggests, the spacer layer simply fills space.
Membrane switches are designed with a circuit layer. The circuit layer is found directly below the spacer layer. The spacer layer, in fact, separates the circuit layer from the membrane overlay layer. Finally, membrane switches feature rear adhesive and tail filler, both of which are located behind the circuit layer.
Silver vs Copper Membrane Switches
While membrane switches feature a flexible substrate, they still use conductive materials for their circuits. You can find silver circuits in membrane switches, and you can find copper circuits in membrane switches.
Kapton circuits leverage a copper and polyimide construction. They typically cost more than silver circuits, but they offer several advantages. With their copper and polyimide construction, Kapton circuits are better protected against the elements. They can withstand moisture without degrading. Kapton circuits also have a higher current carrying capacity than silver circuits.
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