ZhiJian Hardware

Metal dome array, which is a PET sheet containing metal shrapnel (dome), is used as a switch on circuit boards such as PCB or FPC, and plays an important role between the user and the instrument. The role of tactile switches.

Compared with traditional silicone buttons, the conductive film has a stronger tactile feeling, longer service life, and can indirectly improve the productivity of various types of power switches using the conductive film. The metal shrapnel on the button of the dome is located in the conductive position on the PCB (most of them are located on the fiery red gold finger on the pcb circuit board). When it is lightly pressed, the positioning point of the spring is concave and touch The route on the PCB, and then the control loop is generated. According to the amount of current, all the products are in normal operation. That's how it works. According to the different structure of the product, it can be divided into two four categories:

1. One-sided structure

This is also the original relatively simple structure, the metal dome is located under the Mylar (a layer of glued PET), and there are vents to ensure the basic touch and application.

2. Double-layer structure

Unlike the single-sided conductive film, it has an additional layer of Spacer (spacer), the spring sheet is stronger than the glass attached to the Mylar, and maintains a stable touch with the pcb circuit board, with a stronger touch (some Similar to the 'packing' of the membrane switch) In addition, the vent on the double-layer conductive film can more reasonably prevent the PET layer from being scratched by the burrs of the spring sheet, and at the same time, it can also prevent dust from entering the PET layer. .

3. EMI packaging and printing

On the top of Myalr (viewed from the front of the device), a layer of conductive silver paste is printed on the package - that is, ESD (Electrostatic Discharge Control). The key to EMI is to avoid electrostatic induction caused by electronic devices and derived products to the overall target household appliances. damage. ,

4. Rubber glue

A layer of Rubber glue (special type for silicone paste) is packaged and printed on the Mylar or EMI layer, so this type of product can stick firmly to PCB/FPC and other pcb circuit boards.

5. Dome button with Plunger

On the Myalr of the single-sided or two-layer spring sheet conductive film, a protruding point with a relative height of 0.1~0.25mm and a diameter of 0.5mm~1.5mm is added to achieve a special structural composition and improve the tactile feel of the spring sheet. Use 4mm or 5mm annular spring leaf or oval spring leaf with convex conductive film products, the total relative height is 0.35~0.50mm.

It is suitable for mobile phones, virtual phones, various smart remote controls, MP3/MP4, tape recorders, digital cameras, children's learning machines, mobile game control keyboards, microwave heating, car dashboards, looking glasses, small toys, etc. Compared with the pvc membrane power switch used before, it has a stronger touch and a longer service life.

Metal shrapnel (dome), English metal dome, is made of stainless steel. It is a main component of the power switch. With the conductivity of the metal shrapnel, there is a high-quality power switch between the operator and the product. effect. At the same time, using the stable resilience of the dome pieces (self-returning after pressing and holding), and a long service life, give the operator excellent tactile feedback. Leaf springs are suitable for membrane switches on rigid boards such as printed circuit boards.