Mobile phone film switch is mainly based on Metal dome array, which is a piece of PET chip containing metal shrapnel, used as a switch on PCB or FPC circuit boards. It plays an important role of touch switch between users and instruments. Compared with the traditional silicone buttons, the conductive film has better handle, longer life, and can indirectly improve the production efficiency of various types of switches using conductive film.
The working principle of the mobile phone film switch: The metal shrapnel on the conductive film of the metal shrapnel is located on the conductive part of the PCB board (mostly above the golden finger on the circuit board). When pressed, the central point of the shrapnel is concave and touches the circuit on the PCB, thus forming a circuit. The current passes through, and the whole product can work normally.
Make the irregular membrane switch according to the customer's request. In fact, these products are based on customer's drawings or requirements, there is no so-called standard parts or inventory.
However, according to the different structure of cell phone membrane switch, it can be divided into four categories:
1. Single layer structure
This is the simplest structure in the beginning. The metal shrapnel is located below Mylar (a layer of adhesive PET) and has air vents to ensure the basic feel and use.
Two, double-layer structure
Unlike single-layer conductive film, it has a layer of Spacer (spacer). The shrapnel is better attached to Mylar and keeps good contact with the circuit board. It has a better handle. In addition, the ventilation holes on the double-layer conductive film can effectively prevent the PET layer from being scratched by the razor burrs of the shrapnel, and also prevent the dust from entering the PET layer.
Three, EMI printing
There is a layer of silver paste printed on the top of Yalr, namely ESD (Electrostatic Discharge Control). EMI is mainly used to prevent electrostatic damage to the target electrical appliances caused by electronics and its surrounding products.
Four, Rubber glue
Rubber gel is printed on the top of the Mylar or EMI layer, so this type of product can be firmly adhered to PCB / FPC and other circuit boards.
