Customized Conductive Rubber Keypad

Molded silicone rubber keypads have been used in the electronics industry for over thirty years. Rubber keypads offer a 3-dimensional operating surface that appeals to end-users. Original Equipment Manufacturers (OEMs) still have complications when trying to specify features that make sense for their requirements. This article goes into detail about the range of design features available while comparing and contrasting the differences between the two basic styles.

Keypad designers need to understand the various features and trade-offs to choose the best design style for their application.

Conductive rubber keypads contain a semi-conductive pill or puck that is pre-molded with a mixture of carbon particles and silicone rubber (Figure 2). The mixture contains enough carbon particles so that the surface is somewhat conductive but with enough silicone rubber to hold the carbon particles together. The pill or puck is permanently attached to the bottom of the keytop at each switch location during the final molding operation. The pills are placed in the mold in a similar fashion to insert molding used for molding terminals in electrical connectors.