Membrane switch is an operating system which integrates key function, indicating element and instrument panel. It consists of panel, upper circuit, isolation layer and lower circuit. In order to touch the on type normally open switch lightly, the upper and lower contacts of the membrane switch are in the open state under normal conditions. Press the membrane switch, the contact of the upper circuit is deformed downward, and the contact with the electrode plate of the lower circuit is conductive. When the finger is released, the contact of the upper circuit bounces back, the circuit is disconnected, and the circuit triggers a signal. The membrane switch has strict structure, beautiful appearance and good sealing performance. It has the characteristics of moisture-proof and long service life. It is widely used in electronic communication, electronic measuring instruments, industrial control, medical equipment, automobile industry, intelligent toys, home appliances and other fields.
Types of membrane switch materials:
In addition to flatness and printing adaptability, the material of membrane switch and panel should be flexible and highly elastic.
1. PVC \ 60 ℃ \ 0.175 ~ 0.5/smooth \ stable to acid, alkali and salt at room temperature. It has good wear resistance, flame resistance and self extinguishing, noise elimination and shock absorption, and good electrical insulation. Poor thermal stability. Low cost common signs and panels. The membrane switch, also known as light touch keyboard, adopts the integrated sealing structure composed of flat and multi-layer. It is a new type of electronic component that integrates light, machine and electricity, and seals the key switch, panel, mark, symbol display and board together. It is a fundamental change in the appearance and structure of electronic products. It can replace the key of conventional discrete components. Perform operating system tasks more reliably.
2. Polycarbonate PC \ - 60 ~ 120 ℃ \ 0.175 ~ 1.0 \ has high light transmittance, low water absorption, good dimensional stability, excellent bending, tensile and compressive strength, excellent heat resistance, cold resistance, electrical insulation and atmospheric aging resistance. The circuit of output interface terminal is generally made of carbon material and printed without protective coating. It is oxidized by air to form falling off layer gradually, which eventually leads to open circuit and end of service life. This is the place where membrane switch is most prone to failure. It is mainly determined by the environment. Whether it is used or not, the physical damage time is 3 -10. Generally, it has the most extensive application range. In addition to meeting the requirements of most membrane switch panels, the high transmittance of glossy PC can meet the requirements of LCD windows.
3. Sanding polyester (PET) \ - 30 ~ 120 ℃ \ 0.1 ~ 0.2 glossy drug resistance is good, insoluble in general organic solvents, alkali resistant. It has excellent mechanical properties, electrical properties, rigidity, hardness and the largest strength and toughness of thermoplastic, low water absorption, excellent wear resistance and friction resistance, and high dimensional stability. The tensile strength is comparable to that of aluminum film, much higher than that of PC and PVC. Because the surface is difficult to be processed into Matt type, textured pet is the most ideal substrate for making thin film switch circuit. Among them, textured pet is suitable for products with high surface requirements or LCD windows.