How does the membrane switch work?

The membrane switch  is a multi-layer structure (plane) type (non-locking) key switch composed of a certain elastic insulating material layer, which integrates the functions of key, indicating element and instrument panel. The action of the Membrane switch is only realized by the vertical elastic motion of the elastic film, although the elastic film has millions of peristalsis, and the amplitude of peristalsis is very small, only 0.1-0.3MM, coupled with the rationality of material selection, so the film material can withstand more than one million times of large life without deformation, which determines the durability of the Membrane switch.

The membrane switch  has beautiful appearance, long service life, simple structure, easy installation, good feel, small occupation area and other characteristics, and is widely used in all walks of life, from small household appliances to high-tech products, slowly replacing some of the market of the tap switch, occupying a large share in the market.

Generally speaking, the common membrane switch  is mainly composed of 6 layers of material, in accordance with the order from the table to the panel, the surface glue, the upper circuit, the isolation layer, the lower circuit, the substrate. The structure of each layer is described below:

1) Panel: The panel is the "coat" of the entire membrane switch . On the basis of properly arranging the keys, it plays the necessary decorative role for the entire membrane switch  through different colors, patterns and key shapes. The most important role of the panel layer is to play the role of identification and buttons, so the selection of materials must have high transparency, high ink adhesion, high elasticity, folding resistance and other characteristics.

2) The upper circuit, the lower circuit: the upper circuit and the lower circuit are the electrical components of the membrane switch , and the "off" and "key" of the switch, whose performance directly affects the performance of the switching appliance, mainly formed by printing a layer of conductive material on the film. The upper and lower circuits play the two electric shock roles necessary for switch closure, and their thickness is generally within 0.05-0.175mm, the most common is 0.125mm PET.

3) Surface adhesive, isolation layer, base adhesive: the materials of these three layers are double-sided adhesive, which have different names because of their different positions in the switch structure. The three layers of double-sided tape have different thicknesses by different levels, which are mainly determined by the thickness of the switch and the operating force of the key.

The basic working principle of the membrane switch  in the factory is as follows: when the panel is not pressed down, the membrane switch  is in a normal state, and the upper and lower contacts are disconnected, and the isolating layer acts as an isolating effect on the upper and lower lines; When the panel is pressed down, the contact of the upper circuit deforms downward, recombines with the lower line to make the line on, and the line after the conduction gives a signal to the external connecting instrument (substrate), so as to realize its corresponding function; When the finger is released, the upper circuit contact bounces back, the circuit breaks, and the loop triggers a signal.