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Custom Membrane Switches and Keypads

What is a Membrane Switch?

A membrane switch is a momentary electrical contact on/off switch that activates or deactivates an electric circuit. These are sometimes called single pole, single throw, normally open (SPSTNO) switches. Custom membrane switches are manufactured by screen printing the circuit directly onto a plastic substrate with silver or carbon conductive ink. The simple, versatile, durable, and economical design of a custom membrane switch makes it a superior alternative to the mechanical switch.

Membrane switches are used in a wide variety of industrial and consumer applications such as:

  • Medical testing and diagnostic equipment
  • Any industrial manufacturing equipment with a control panel
  • Household appliances such as microwave ovens and stoves
  • Retail/consumer applications such as vending machines, kiosks, exercise equipment, and gasoline pumps
  • Military equipment to handle rogue treatments

Membrane Switch Components

Membrane switches typically have the following basic layers:

  • Graphic overlay with subsurface printed text/graphics and a polyester or polycarbonate layer with or without embossed keys
  • ESD shielding layer (optional)
  • Spacer and/or dome retainer
  • Polyester printed circuit layer
  • Rear adhesive with liner
A membrane switch produced by Design Mark Industries

Optional features on membrane switches include:

  • Custom printing, logos, and graphics
  • Surface texture materials
  • Custom shapes
  • Backlighting (fiber optic or electroluminescent)
  • Multiple tactile dome options for tactile feedback or non-tactile option
  • EMI/ESD/RFI shielding options (for electro-magnetic interference, electro-static discharge and radio frequency interference shielding)
  • Embossing
  • Embedded LEDs and/or resistors
  • Multiple connector styles
  • Sealed to keep out incidental dust and moisture
  • Window lens coating
  • Many more options are available

Membrane Switch Materials

The graphic overlay surface or faceplate material is one of the main considerations in designing a custom membrane switch, with polycarbonate and polyester being the most commonly used materials. Polycarbonate is clearer, easier to fabricate and print but is less durable in constant use. Polyester is more challenging in its manufacturing, yet it is more durable and has better resistance to environmental conditions. Polycarbonate is slightly less expensive than polyester, but the difference is minimal and not usually a major consideration.

Our membrane switch design and engineering team will guide you to help you chose the best membrane switch product based on your needs and the conditions in which the membrane switch will be used. Hard-coated materials are also available to reduce gloss/glare and provide added durability, scratch-resistance, and chemical resistance.

Membrane Switch Characteristics

Membrane switches are available in various forms and are capable of providing different feedback levels to the user. When you work with us, you’ll notice we use terms such as audible, tactile, snap acting dome and poly-dome when discussing the feel and behavior of your membrane switch.

A membrane switch produced by Design Mark Industries
  • Characteristics of traditional membrane switches – Traditional switches use a printed polyester membrane with a printed layer of conductive silver ink as the circuit and actuation layers. Membrane layers are separated by a spacer that provides a gap between the upper and lower circuit to keep the switch in an open state. Pressing on the switch location compresses the upper circuit and causes the printed silver contact area to bridge the gap, close the contact, and complete the circuit. When pressure is released, this restores the gap. This type of membrane switch does not provide any feedback to the user other than the event taking place.
  • How to provide audible and tactile feedback – We can employ a physical contact in the form of a plated metal contact disc, commonly referred to as a dome. When pressed, this dome will snap through a centerline and contact the lower circuit, which can produce an audible “click” and tactile “thump.” This closure action provides tactile and audible feedback to the user on the successful completion of the circuit closure.
  • Additional options – We can also incorporate a thermal-formed polyester switch layer at the contact locations (printed with conductive silver) that are embossed (raised) to form a dome. These poly-domes then take on some of the behavior of a snap acting metal dome to provide positive tactile feedback, but they generally do not provide audible feedback. Another option is to employ a hybrid design that incorporates a printed circuit board (PCB) as the lower circuit and any combination of membrane, dome or poly-dome employed as the upper circuit.

When you collaborate with Design Mark’s membrane switch design and engineering team, we’ll work with you to determine the appropriate specifications and options for your product’s membrane switch.