Today, the global membrane switch market has a market size of approximately $4.2 billion in 2015 and is expected to grow to $13 billion by 2025. Membrane switches are extensively used in industrial, medical, and consumer goods applications.
Membrane switches are extensively used in a variety of applications may it be domestic, commercial, or industrial. There are other types and forms of user interfaces such as touchscreens, keyboards, switches, and selector knobs. Membrane switches are preferred because of their compact profile, simple construction, reliability, resistance to harmful elements, and low cost. These advantages are further elaborated below.
Thin and compact profile: Each plastic layer of a OCA membrane switch can have a thickness of about 0.005 to 0.040 inches. They typically have three to six layers depending on the design. Even applying the conductive and graphic inks and installing other components such as the metallic domes and EMF screens, the final thickness still results in only a fraction of an inch. This makes them suitable for household appliances and equipment controllers with small form factors.
Overlay: Also known as top or graphic overlay, the overlay is the outermost layer of the elevator program control membrane switch. Since this layer is on the exposed side of the membrane switch, it is made from materials that have good flexibility, clarity, durability, chemical resistance, and barrier properties. There are two common materials used for making the overlay,
Spacer Layer: This layer is used to create a break in contact between the two conductors of the switch. This allows the switch to have its open position. In some designs of membrane switch with led, it can also act as a retainer to keep the metallic dome in place. The spacer layer has channels between the empty cavities or the sides of the keypad for venting air. This prevents air from being compressed in the cavity when the key is pressed.
Circuit Layer: This layer is where the conductive paths of the switch are applied. These conductive paths can be produced through two main methods: screen printing and photochemical etching.
Screen Printing: This method uses a stencil containing the pattern of the circuit. Silver conductive ink is flooded on the stencil which is placed above a substrate. The substrate used is typically a polyester film. This method is used for thinner and more flexible membrane keypads.
