Membrane switches have become a popular alternative to traditional plastic switches. Defined by ASTM International as being an electrical switch with at least one flexible substrate, they offer an unparalleled level of performance compared to plastic switches. Membrane switches are comfortable to use, produce natural tactile feedback and offer moisture and liquid resistance.

When exploring the inner working of membrane switches, you’ll probably discover that most are designed with conductive ink. The ink used for printing the circuit, for example, is made of a material that conducts electricity, with copper, silver and graphite being the most common. So, why do membrane switches use conductive ink?

Conductive Ink: The Basics

To better understand why membrane switches, you must first understand how conductive ink works. Conductive ink is used like any other type of ink to produce circuits. The difference between conductive ink and other types of ink, however, is that only former allows electricity to flow through it.

Conductive Ink Allows for a Controlled Circuit

Using conductive ink allows for a controlled circuit in membrane switches. When you press a key, the conductive ink will come into contact with an underlying conductor, thereby closing the circuit and registering your command. When you release the key, the circuit will revert back to its default open position.

Without the use of conductive ink, electrical contact would have to occur using an alternative method. There are other ways to design membrane switches, but conductive ink allows for a simple and effective design.

Does the Type of Conductive Ink Matter?

As previously mentioned, there are several types of conductive ink, some of which include silver, copper and graphite. While there are nuances between them, they all serve the same purpose of allowing for a controlled circuit. As a result, the type of conductive ink used in a membrane switch won’t affect the switche’s performance or functionality.

Other Things to Consider When Choosing a Membrane Switch

Along with whether it has conductive ink, there are a few other things to consider when choosing a membrane switch. Some membrane switches, for example, feature backlighting. Membrane switches support light-emitting diode (LED), fiber optics and electroluminescent (EL) backlighting. Of course three options, LED is often preferred because of its energy-efficient properties combined with a long lifespan.

To recap, conductive ink is used in membrane switches because it allows for a controlled circuit. When you press a key, a circuit containing the conductive ink will come into contact with an underlying conductor to close the circuit.