Membrane Switch Connector Options

Membrane Switch Connector Options

 

Membrane switch connectors connect the keypad to the product, device or machine. Connectors consist of contacts and molded plastic housings. Membrane switches are connected utilizing a flexible tail that is cut from the circuit material. This flexible tail can be inserted or connected to a printed circuit board with a variety of single row connectors designed for flex circuits. Alternatively, the tail can be designed to connect with a Zero Insertion Force (ZIF) connector. ZIF connectors have become extremely popular and industry norm. Solder tabs are also an option that can be considered

Connector Options:

  • Bare tail: interfaces to .100” center LIF or ZIF style connector
  • Female connector: Plain – interfaces to a .100” center, .025” square posted header
  • Female connector: Latching – interfaces to a .100” center latching header
  • Male connector: Plain – interfaces to a .100” center female header
  • Male connector: Latching – interfaces to a .100” center latching header
  • Solder tabs – .100” centers and can be directly soldered to PCB or wires
 

ZIF Connectors

ZIF connectors are assembled to the PCB end and therefore there is no physical connector on your membrane switch side (the end of the flex tail is bare). ZIF connectors typically have a low profile, are lightweight, secure, and removable connections. ZIF connectors are appropriate for more complex applications and allow for higher levels of integration. The tail of the circuit is inserted into the ZIF connector to create the contact, and a stiffener is laminated under the tail to ensure stability and maintenance of the electrical contact. ZIF connectors may have anywhere from 2 to 30 positions on a single row, and distances of between 1mm and 2.54 mm are available.

Male, Female, or Solder Tab Housings

These types of connectors are considered to be more reliable against heavy shock and vibration. They also are known for more ease of assembly. With a much larger connection, male, female, and solder connectors have pins crimped to the circuit and are available with many different housing features. The tail pitch is available in .100” spacing.

Crimpflex Connecting System by Nicomatic

Nicomatic Crimpflex connectors conform to Berg, Molex, and Amp membrane switch connecting specifications by utilizing common pins in a specific housing to meet connection requirements. The Crimpflex crimping presses are dedicated to the manual and pneumatic crimping of male and female contacts and are known for their reliability, ruggedness, simplicity of use, speed, and precision. The Crimpflex contacts ensure mechanical retention and electrical contact by piercing the conductor in six points. The contacts are available in male, male solder tab, and female versions; the female contacts are selective gold or tin-plated. Crimpflex connectors’ standing housings are available in the OF series, which fits with the most common interfaces, or the OM series, which interfaces with cables and comes with an locking system that can be oriented to meet your specifications.

Membrane Switch Construction

Membrane Switch Construction

 

Typically a membrane switch assembly typically consists of six to seven main layers:

 

  1. Graphic Overlay – Graphic overlays are typically constructed of polyester, the material of choice due to its superior chemical resistance and flex life compared to polycarbonate. CSI can either digitally print, screen-print, or employ a combination of both methods to insure you get the right colors, textures, and finishes your Silver Flex membrane switch design requires.
  2. Overlay Adhesive – The overlay adhesive layer bonds the graphic overlay to the top circuit layer. This overlay adhesive is typically an acrylic adhesive, selected for its durability and ability to maintain adherence in atypical environments, such as moist environments.
  3. Top Circuit Layer – Typically a .005″ – .007″ heat-stabilized, polyester printed layer with silver-filled, electrically conductive inks and dielectric inks. This layer can also encapsulate metal domes or incorporate polydomes, which are used to achieve tactile feedback, an important design consideration impacting usability.
  4. Circuit Spacer – This layer separates the top circuit from the bottom circuit, so the switch remains normally open until the keypad is pressed. The circuit spacer is a polyester spacer with adhesive on both sides.
  5. Bottom Circuit Layer – The lower circuit layer is typically a .005″ – .007″ heat-stabilized, polyester-printed layer with silver-filled electrically conductive inks and dielectric inks. This layer terminates as a flexible tail that serves as the interconnect to controller PCB’s or other electronics.
  6. Rear Adhesive Layer – This adhesive layer bonds the entire membrane switch package to the product enclosure, housing, or to a rigid support panel. CSI can specify the appropriate adhesive type and thickness to bond your membrane keypad to your equipment.
  7. Rigid Support Layer – This optional layer can add structural integrity to the membrane switch assembly. Materials can be aluminum, FR-4, steel, etc. Mounting hardware such as studs and standoffs can also be utilized in this layer.
CSI Keyboards Membrane Switch Construction and Layers

General Considerations When Designing a Membrane Switch

General Considerations When Designing a Membrane Switch

 

Environmental

• What temperature and humidity range will this product experience?
• What types of contaminants or chemicals will come into contact
with this product?
• Will this product be subjected to moisture and/or U.V. exposure?

Mechanical

• Will tactile response be required?
• To what material will the switch be laminated?
• What number of actuations will this product receive?

Electrical

• How many contact points will there be?
• What type pinout or matrix will be used? (common bus, X-Y matrix)
• What closed loop resistance will be acceptable?
• Will electrostatic or EMI shielding be necessary?

Appearance

• Will edges be exposed, recessed, or covered with a bezel?
• Will embossing be required?
• Will there be different parts to the same product? (sets)
• How many colors will be needed?

Benefits of Using Membrane Switches

Benefits of Using Membrane Switches

 

Thin Construction: Membrane switches are extremely thin in construction, especially in comparison to other technologies such as mechanical switches.

Environmentally Sealed Construction: Membrane switches can be designed with a sealed construction design preventing moisture or contaminant ingress.

Low Profile: Membrane switches have a low profile surface which allows for easy cleaning.

Cost Effective: Membrane switches are extremely cost effective especially in comparison to other user interface technologies. 

Customizable: Membrane switches are easy to customize, giving customers the ability to achieve the look and feel that they desire including customizable graphics, domes, keys, texture, size/shape, windows, etc.

CSI Keyboards Membrane Switch
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