One, key switch shrapnel understanding
  1. The button switch shrapnel (also commonly known as the metal dome, snap dome) is made of ultra-thin (0.05mm-0.1mm thickness) and ultra-thick (generally higher hardness) stainless steel 301 or 304 materials. The button shrapnel is an important part of the switch.
  2. The button shrapnel is mainly used in membrane switches, dome contact switches, PCB boards, FPC boards, medical equipment and other products.
  The working principle of the button shrapnel: The button shrapnel on the membrane button is located on the conductive part of the PCB board (mostly located above the golden fingers on the circuit board). When pressed, the center point of the shrapnel is concave and touches the circuit on the PCB. , Thus forming a loop, the current passes through, and the whole product can work normally.
  3. Generally, conventional button shrapnels can be divided into round metal shrapnel, cross-shaped metal shrapnel, triangular metal shrapnel, and oval metal shrapnel according to their different shapes. The diameter ranges from 3mm to 20mm, and the strength ranges from 100gf to 600gf.
  4. The button switch shrapnel can be divided into gold plating, nickel plating, silver plating, bright surface, etc. according to the surface electroplating treatment. There are two types of single-sided electroplating and double-sided electroplating.
Second, the role of the button switch shrapnel
  1. Shrapnel is an important part of the key switch. When it is used to meet the conditions of operating force, apply pressure to the switch operation direction. The switch function is closed and connected. When the pressure is removed, the switch is opened. Its internal structure is stressed by the metal shrapnel. Change to realize the on-off of the circuit.
  2. At present, the shrapnel of the key switch can be divided into domestic shrapnel and imported shrapnel according to the quality area. Imported shrapnel is relatively better in quality, but the price is also higher.
  3. According to the material, it can be divided into stainless steel shrapnel and ordinary shrapnel. According to the shape, it can be divided into square shrapnel and round shrapnel. However, since the quality of the shrapnel will directly affect the normal use of the key switch, the shrapnel needs to undergo aging test, salt spray test and other tests to ensure that it is not easy to be rusted and aged.
  4. The choice of square and round shrapnel should be considered according to the needs of the key switch. In the case of the same material, the service life of round shrapnel is generally longer than that of square shrapnel, but the price of square shrapnel is relatively cheaper. Compared with round shrapnel, it is easier to process and save materials.
  5. So if the button switch wants to have the price advantage, you can consider the square shrapnel, and the round shrapnel is more recommended for those with higher requirements on the life quality.
  6. The shrapnel is an important part of the key switch to realize the circuit on and off, so the quality of the switch shrapnel must be paid great attention to, otherwise it will easily affect the normal use of the key switch.