12-button, embossed key, membrane switch with integrated window, designed and manufactured for Baxter Healthcare

A membrane switch is a type of electrical switch that’s made of a flexible material. Like all electrical switches, it’s used to turn a circuit on and off. Membrane switches are distinguished from their counterparts, however, by featuring a flexible construction. With that said, they also contain conductive ink. Some membrane switches use copper ink, whereas others use silver or graphite ink. Regardless, most membrane switches are designed with conductive ink. So, what’s the purpose of this conductive ink exactly?

The Basics of Membrane Switches

To better understand why membrane switches have conductive ink, you must first take a closer look at how they are constructed. While different membrane switches are constructed in different ways, most consist of a few basic layers. There’s the top layer that features the printed graphics, followed by a spacer layer and then a printed circuit layer.

Underneath the top layer of a membrane switch is an electrical contact. There’s also an electrical contact on the underlying printed circuit layer. When you press a membrane switch, the two contacts will meet, thereby completing the circuit. When you release your finger from the switch, the top contact will pull away from the bottom contact, thereby breaking the circuit.

Conductive Ink Completes the Circuit

The electrical contacts used in membrane switches typically consist of conductive ink because it allows for the completion of a circuit. The term “conductive,” of course, refers to an object’s or material’s ability to transfer electricity. Not all materials are conductive. Some materials are significantly more conductive than others.

Conductive ink is used in membrane switches to facilitate the flow of electricity, which in turn allows for the completion of the circuit. If membrane switches used a non-conductive ink, they wouldn’t function as intended. Pressing the membrane switch essentially wouldn’t do anything. Conductive ink, on the other hand, allows membrane switches to complete the circuit when pressed.

Conductive Ink Saves Space

There are other types of conductive materials that can be used instead of conductive ink. Conductive ink, however, is often preferable because it consumes little or no space. Membrane switches are typically small, so they require equally small components. Thankfully, conductive ink is the perfect solution because it consumes little or no space.

Membrane switches use conductive ink to complete the circuit. Some use copper ink, whereas others use silver or graphite ink. The conductive contacts allow the switch to function as intended.