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Membrane Switch Layers
Posted by Nancy Figueroa | July 2021
If you've ever operated a microwave oven, washing machine, or any device with a keyboard, you've likely interacted with a membrane switch without even realizing it. As end-users, we often only engage with the functionality of these devices without delving into their technical aspects. However, have you ever wondered how communication occurs between us and these devices? How exactly does a keyboard function, and what materials are involved? In this article, we'll explore some key features and provide a basic overview of a membrane switch.
What is a Membrane Switch?
A membrane switch, also referred to as a flexible keyboard or membrane keypad, serves as the intermediary between a machine and its user, enabling the transmission of instructions from the user to the machine.
It comprises thin, flexible layers and can come in tactile or non-tactile variations.
Tactile switches feature metal domes to simulate the sensation of pressing a button, while non-tactile switches lack domes but frequently incorporate LED indicators.
Applications
Membrane switches are found in many devices and machines from different industries such as:
Home appliances (washing machines, microwave ovens, fridges, etc)
Medical equipment (instruments, beds, monitoring systems, etc.)
Food processing equipment (fryers, ovens, etc.)
Industrial machinery
Membrane Switch Components
A membrane switch may incorporate various materials such as polyester, polycarbonate, conductive inks, metal domes, adhesives, resistors, and LEDs. These materials are typically arranged in thin layers, typically ranging from 4 to 6 layers.
Below, we'll illustrate an example of a membrane switch featuring a basic keyboard design.
Graphic Overlay
This layer is what the user sees and interacts with. In this example, the design is that of a keyboard.
Graphics are applied using either screen printing or digital printing methods.
Adhesive
This layer is used to join the graphic overlay layer and the dome retainer layer.
Dome Retainer
This layer keeps the domes from the previous layer fixed in place.
Spacer and Metal Domes
This layer contains metal domes that, when pressed, complete the circuit. Concurrently, the spacer provides room for the domes beneath the graphic overlay.
Circuit
This layer contains the circuit- a set of conductive paths that are screen printed using a conductive ink.
Mounting Adhesive
This layer is used to facilitate the assembly of the finished membrane switches to any device or machine.
Additional Components
Illumination features such as indicator LEDs, backlighting, or electroluminescence, can be implemented to enhance the look and operation of our products. To learn more, click here.