From aerospace and video gaming to medical and industrial, membrane switches are used in a variety of industries. Like other switches, they are designed to control an electrical circuit. Membrane switches are unique, however, because they are made of a soft and flexible material, such as polyester. While different membrane switches are designed in different ways, most are manufactured with the five following layers.
Most membrane switches are designed with an overlay layer on the outside. The overlay layer features the keys and legends of a membrane switch. Without this essential layer, you wouldn’t be able to see the buttons, thereby rendering the membrane switch useless. The overlay layer is made of a soft and flexible material to provide a superior level of comfort and performance.
After the overlay layer is the spacer layer. As the name suggests, this is simply a layer of open space. The purpose of the spacer layer is to separate the overlay layer from the printed circuit layer. With the added space between these two layers, pressing a key or legend on the overlay layer will force it to make contact with a printed circuit, allowing for the completion of the circuit.
#3) Printed Circuit
Below the spacer layer is the printed circuit layer. This is the primary circuitry powering the membrane switch. The printed circuit layer contains conductive ink or traces that closes the electrical switch when a key or legend is pressed. When you press a key, for example, the conductive ink on the bottom of the key will push through the spacer layer before contacting the printed circuit layer. When you release the key, the electrical circuit reverts back to its default, open position.
The adhesive layer is designed to secure the membrane switch to the container or product in which it’s installed. While the adhesive layer may sound insignificant, it still plays a key role in the function and overall performance of a membrane switch. If the wrong adhesive is used, the membrane switch may pull or break away from the container or product in which it’s installed.
Some membrane switches also have a fifth layer — the filler layer. The filler layer doesn’t serve any functional purpose. Rather, it’s used to “fill” any voided space surrounding the membrane switch.