Electrical switches play an important role in the function of modern-day electronics. Whether it’s a human machine interface (HMI), control pad, household appliance, etc., it allows the operator to control the flow of electricity to and from the respective device. But there are several different types of electrical switches, one of which is the membrane switch. To learn more about the membrane switch and how it works, keep reading.
Traditional electrical switches fall under the category of being mechanical. A mechanical switch is typically made of copper and/or plastic components, with copper being a highly conductive material through which electricity passes and plastic being a resistive material that prevents the flow of electricity. A membrane switch, however, differs in the sense that it uses a different design. While mechanical switches are made of copper and plastic, membrane switches consist of a circuit printed on either Polyethylene terephthalate (PET) or Indium tin oxide (ITO). Membrane switches also use either copper, silver or graphite materials for the ink.
Why are metals like copper, silver and graphite used for the ink in a membrane switch? Much like copper is used to facilitate the flow of electricity in mechanical switches, copper, silver and graphite also facilitate the flow of electricity in a membrane switch. These metals are conductive in nature, making them a key component in the function of a membrane switch.
As explained by Wikipedia, membrane switches are classified as an “interface utility,” as it allows a human operator to command or otherwise control an electronic device. Other interface utilities include tactile switches, HMIs and touchscreens. The purpose of an interface utility is to provide a means of controlling an electronic device. With a membrane switch, the operator controls the device by switching the flow of electricity either on or off. This doesn’t necessarily mean that a membrane switch only works as an off/off toggle button. Rather, it is designed to either allow or deny the flow of electricity.
According to the ASTM, a membrane switch is characterized by an electrical switch in which “at least one contact is on, or made of, a flexible substrate.” Mechanical switches contain many hard mechanical components, but a membrane switch features a flexible substrate. Most membrane switches also contain at least four years, with the top layer featuring the graphic interface. Another essential layer is the printed circuit, which either allows or restricts the flow of electricity to the respective connected.