Spacer Layer

Purpose and Function of the Membrane Switch Spacer Layer

Diagram of a membrane switch spacer layer

The spacer layer provides the gap between the circuits of the membrane and static layers. For non-tactile membrane switches, the spacer controls the travel duration and keeps the circuit open between actuations. In addition to these function, tactile switches require a spacer layer to provide clearance for the domes.

The thickness of the spacer layer is an important consideration in designing membrane switches for proper functioning. If it is too thick, the switch will be difficult or impossible to operate. If the spacer is too thin, the switch may be actuated inadvertently.

Membrane Switch Venting

Another important function of the spacer is to provide venting for the switches. Venting allows air to flow in and out of the switches during actuation. Without venting trapped air can cause excessive pressure preventing switch operation or create a vacuum that distorts the graphic layer and domes after actuation preventing them from returning to their original position. Careful consideration must be given to the placement of venting lines to maintaining proper air pressure, prevent contaminants from disrupting circuitry and to preserve ideal operating temperature.