Utilising PET film as the circuit substrate and integrating metal dome contacts, this design achieves circuit switching through mechanical deformation. It offers stable conductivity and extended press endurance, delivering over 500,000 press cycles within a 0.5–1.2mm travel range, with contact resistance below 50mΩ.
Metal Dome: This constitutes the core element of the dome switch, typically crafted from stainless steel or phosphor bronze. It adopts a circular or elliptical dome shape, resembling a miniature pot lid – hence the name ‘pot lid switch’.
PCB Contact Point: Positioned beneath the switch, this corresponds to the contact point on the circuit board, generally located at the gold-plated contact area on the PCB. When the dome switch is depressed, the base of the metal dome contacts the PCB contact point, completing the electrical circuit.
Keycap: Some dome switches incorporate a keycap positioned above the metal dome. Users directly press the keycap to operate the switch. Keycaps vary in shape, size, and material; for instance, plastic keycaps are injection-moulded and may feature surface treatments such as silk-screen printing for text or graphics.
Single-layer structure: The most basic and original design, where the metal dome is positioned beneath a single layer of adhesive-backed PET (Mylar), featuring ventilation holes to ensure fundamental tactile feedback and functionality.
Double-layer structure: Compared to the single-layer design, this incorporates an additional spacer layer. The metal dome sheet adheres more effectively to the Mylar and maintains superior contact with the circuit board, delivering enhanced tactile feedback. The ventilation holes also provide more effective protection against scratches from burrs on the metal dome sheet potentially damaging the PET layer, whilst simultaneously preventing dust ingress.
EMI Printed Structure: A layer of silver paste, known as ESD (Electrostatic Discharge) control, is printed onto the Mylar. This primarily prevents damage to target electrical equipment caused by static electricity generated by electronic devices and their peripherals.
Raised Dot Structure: Single- or double-layer conductive foil Mylar is further enhanced with raised dots measuring 0.1–0.25mm in height and 0.5–1.5mm in diameter. This configuration accommodates specific structural requirements while improving tactile feedback.
High sensitivity: The dome switch responds to minimal pressure, enabling rapid circuit closure with minimal force applied. This makes it suitable for devices requiring high operational responsiveness.
Excellent tactile feedback: Users experience distinct feedback when pressing the dome switch. The clear tactile sensation as the spring-loaded membrane depresses and returns provides immediate confirmation of successful operation.
Durability: The metal dome leaf exhibits high wear resistance and corrosion resistance. Under normal usage, it maintains excellent performance even after repeated presses.
Compact Design: The relatively compact structure of dome switches enables key functionality within limited space, effectively conserving area.
Ease of customisation: By adjusting parameters such as the material, thickness, and shape of the metal dome, customisation in terms of form, dimensions, and spring force can be readily achieved to meet the requirements of different devices.
