Silicone rubber keypads (also known as Elastomeric Keypads) are used extensively in both consumer and industrial electronic products as a low cost and reliable switching solution.
The technology uses the compression molding properties of silicone rubber to create angled webbing around a switch center. On depression of the switch the webbing uniformly deforms to produce a tactile response. When pressure is removed from the switch the webbing returns to its neutral position with positive feedback. In order to make an electronic switch a carbon or gold pill is placed on the base of the switch center which contacts onto a PCB when the web has been deformed.
Common applications of Silicone rubber keypads include remote controls for TV, Video and HIFI units, Electronic toys and games and industrial control equipment.
With the increased use of low current switching within automobiles, silicone rubber keypads are being used extensively as switch mechanisms for various function buttons such as window lifts and steering wheel mounted controls. With the availability of low resistance pills such as SC pills (produced by Abatek)and Gold pills, short-stroke metal dome contacts (produced by Shin-Etsu Polymer) application of keypad in automotive market has increased significantly.
source: Wikipedia, the free encyclopedia