Silicone rubber keypad

A silicone keypad is the central component in many keyboards, which determines the feel, the visual and tactile impression and the integrated contact pill also the electrical behavior.

Operation and design

A dome or cone is formed from the base material of silicone rubber, which merges with the central axis in a cylinder. The outer end of the cylinder represents the point of application of pressed or the key cap Represents the inner end of the cylinder consists of a contact pill or a snap disk and provides the electrical contact element represents the electrical connectors of a built with silicone keypad button are mostly conductive paths constructed as a comb or meander on a circuit board, which are bridged by the contact pill / snap disk. Usually, several keys are implemented together in a silicone keypad, but there are also individually placeable buttons based on a silicone keypad, in which the connecting wires are arranged in the housing so that they are bridged by the contact pill.

Via the shape of the dome and of the lands and the material properties of the base material used to set the feel and color of the buttons in a wide range. You can determine the electrical properties of the button on the choice of contact pill:

  • Carbon filled or coated: cheap, contact resistance 10 to 200 Ω, small streams
  • Supra Conductive pill (SC- pill): Specially modified nickel grid, filled with silicone, contact resistance less than 1 Ω, relatively cheap, up to 0.3 A current-carrying capacity
  • Gold plate or film: relatively expensive, sensitive to contamination, very low contact resistance, current-carrying capacity up to several amperes
  • Snap disc: relatively expensive, audible contact operation, small contact resistance

Since you can also hard plastic keycaps directly laminated on the actuating cylinder, it is possible to provide the operator with the key a hard surface available, on the design of the button (painted, laser-etched symbol, etc.) with a search and functional illumination can be fitted.

Use

Almost all mobile devices with movable buttons ( mobile phones, digital cameras, remote control, etc.) use silicone keypads for the design of the buttons and keypads.

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