The membrane switch has push button cap (2) formed in an elastic material and on the inner surface of the cap is a contact element (4). When finger pressure is applied the contact is pressed against a contact foil (3). The contact foil is formed on a porous filter mat (8) on a base plate (11). The base plate and the contact foil have ventilation holes (7,9) to allow air to be expelled when the push button is pressed.
