Working principle and process flow of membrane switch

Thin film switch is a multi-layer structure (flat) type (non lock) key switch composed of insulating material layers with certain elasticity, but integrated with circuits The functions of buttons, indicator components, instrument panel, etc. are integrated. The action of the membrane switch is only achieved by the vertical movement of the elastic membrane. Although the elastic membrane undergoes millions of times of peristalsis, the amplitude of peristalsis is very small.

Membrane switch is an operating system that integrates button functions, indicator components, and dashboard. It consists of four parts: panel, upper circuit, isolation layer, and lower circuit. When the membrane switch is pressed, the contacts of the upper circuit deform downwards and make contact with the plates of the lower circuit. After releasing the finger, the contact springs back, the circuit is disconnected, and the trigger signal is triggered. The membrane switch has a rigorous structure, beautiful appearance, and good sealing performance. It has the characteristics of moisture resistance and long service life. Widely used in fields such as electronic communication, electronic measuring instruments, industrial control, medical devices, automotive industry, smart toys, household appliances, etc.

1. The panel layer is usually made of PET, PC or other colorless transparent boards with screen printing of exquisite patterns and text below 0.25mm. Because its function is to serve as a symbol and button, the selected material must have characteristics such as high transparency, high ink adhesion, high elasticity, and high toughness.

2. The main function of surface adhesive and layer adhesive is to tightly connect the panel layer and the circuit layer, achieving a sealed connection effect. This layer is generally required to be 0.05-0.15MM thick, with high viscosity and aging resistance. Special film switch double-sided tape is generally used for production. Some membrane switches require waterproofing and high temperature resistance, so the surface adhesive must also use materials with different properties according to the needs.

3. The upper and lower layers of the control circuit use high-performance polyester film (PET) as the carrier for the switch circuit pattern, and a special process is used to shield conductive silver paste and conductive carbon paste on it to make it conductive. Its thickness is generally within 0.05-0.175mm, with the most common being 0.125MM PET.

4. The sandwich layer is located between the upper circuit layer and the lower circuit layer, serving to seal and connect. Generally, PET double-sided tape with a thickness of 0.05-0.2mm is used; When selecting this layer of material, full consideration should be given to the overall thickness, insulation, circuit key packaging feel, and sealing of the product.

5. The use of adhesive layer on the back is closely related to the raw materials used for attaching the film switch. Commonly used adhesives include regular double-sided tape, 3M tape, waterproof tape, etc.