What is a Membrane Switch and How Does it Work?Learn more about this versatile user interface.
Nelson Miller Group has been a leading membrane switch manufacturer since the technology was commercialized in the 1980s. Membrane switches are user interfaces (also called operator interfaces or human machine interfaces). By pressing a button on an overlay, the operator can achieve a desired effect in a piece of equipment, instrument, or machinery.
Membrane switches are used in a variety of domestic, commercial, and industrial applications. They’re preferred to purely mechanical switches because of their compact profile, simple construction, reliability, resistance to harmful elements, and low cost. Unlike mechanical switches, which are generally constructed with copper and plastics, membrane switches are composed of several thin, flexible layers, including printed circuits on film.
The Different Layers of a Membrane Switch
A membrane switch is an electrical switch assembly that uses contact or pressure to open or close a circuit. They’re constructed from several layers of flexible materials that can be customized to fit your specific design and operating characteristics. However, no matter the design or function, there are a few primary components that can be found in all membrane switches:
The overlay is the top layer of the membrane switch. This is the layer that shows the operator what they’re pressing. The graphic overlay is the exposed part of the switch and is made from materials that have excellent flexibility, clarity, toughness. Manufacturing processes use digital print, screen-print, or a combination of both to ensure the right colors, textures, and finishes.
This layer separates the top circuit from the bottom circuit, so the switch remains open until the keypad is pressed. The spacer ensures that the circuit isn’t activated without intent—the button only registers when it is intentionally pressed.
The circuit is what makes a membrane switch operational and controls the electronic device. They’re printed with conductive inks and may use some dielectric inks to protect the circuitry. This bottom circuit layer terminates as a flexible tail that serves as the interconnect to controller PCBs or other electronics.
Adhesives are crucial since they attach the entire assembly to the end product and bond the graphic overlay layer to the circuit layer.
Membrane Switches Offer Superior Versatility with Design Features
Tactile or Non-Tactile Feedback
Tactile feedback is created by incorporating metal or plastic domes into the membrane switch assembly. When pressing on a dome beneath the graphic overlay, the dome provides the feeling that a “button” is being pressed. The tactile feedback can be designed for various shapes and sizes and different amounts of actuation force, depending on the operator’s needs. In contrast, non-tactile membrane switches are used in applications when a tactile response is not needed. Non-tactile switches typically trigger sound or light to indicate to the operator that function has been activated. Non-tactile switches are preferred when a thin profile is more valuable than tactile feedback.
Backing Panel or Support Layer (optional)
The switch design may require additional rigidity for structural integrity. In many applications, a backing layer isn’t needed because the keypad is already supported by the panel or enclosure of the device itself.
Finishes for Membrane Switches
Finishes add another dimension to the membrane switches. They can augment the durability of the switch (heavy use and chemical resistance), accentuate the graphic elements, improve aesthetics, and/or add tactile dimensions. The different types of finishes are:
- Selective texturing: application of a transparent, scratch-resistant, matte finish.
- Hard coating: a layer of ultraviolet-curable polymer.
- Surface embossing: raising some of the switch’s surface with various heights and patterns.
- Dead front: a cosmetic feature of a graphic overlay in which a membrane switch (or a portion of it) is only visible when activated or backlit.
Nelson Miller Group has tremendous expertise in finishes; our excellent record makes us a preferred membrane switch manufacturer for OEMs.
Benefits of Membrane Switches
- Extremely long lifespan
- Low cost through significantly reduced tooling costs and assembly time
- Thin/low profile, which saves space and reduces crevices that can trap dirt and contaminants
- Strong protection by sealing the device from harsh conditions
- Flexibility of the material
- Ability to produce intricate shapes
- Versatile graphic interface to create an intuitive and appealing visual for the end user
- Long list of features and options available to make the product user-ready
NMG has more than 85 years of experience partnering with organizations to bring their industrial, IoT, lighting, medical, telecommunications, consumer, and aerospace products to life. We solve your most complex challenges in engineering design, manufacturing, and supply chain management.
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