The key switch mainly refers to the light-touch key switch, also known as the touch switch. The key switch is an electronic switch and belongs to electronic components. It first appeared in Japan and was called a sensitive switch. When in use, the switch function is turned off, and the switch is turned on according to the operating direction to meet the operating force. When the pressure is released, the switch is closed, and its internal structure is made and closed by the stress change of the metal spring. The key is composed of an insert, a base, an elastic sheet, a button and a cover plate, in which a layer of polyimide film is added to the elastic sheet of the waterproof touch switch.

The key switch has the advantages of precise operating force error, low contact resistance, and diversified specifications. It is widely used in electronic equipment and white appliances, such as household appliances, communication products, remote controls, digital products, audio-visual products, security products, toys, computer products, medical equipment, fitness equipment, banknote detectors, laser pen keys, etc. Because of the environmental conditions of the key switch, large equipment and high-load keys are directly replaced with conductive rubber or metal shrapnel of pot switches, such as TV remote controls, medical equipment, etc.

The volume of the early key switch was 12mm*12mm and 8mm*8mm, and now it is 6mm*6mm. The key switch is a 4th generation product developed with the development of electronic technology. The products are vertical, horizontal, and horizontal with grounding terminals. There are now two combinations (3M, 4M, SM, 6M, SM) and potentiometer key switch combinations to meet the requirements of various home electronic products. The installation sizes are 6.5mm*4.5mm, 5.5mm*4mm and 6mm*4mm. There are 4.5mm*4.5mm small key switches and sheet key switches abroad. Sheet key switches are suitable for surface assembly. Now there are 5 generations of products-membrane switches, which are mainly used in electronic instruments and CNC machine tools. The functions are the same as key switches, but the resistance is large and the feel is poor. In order to overcome the phenomenon of poor feel, some membrane switches use contact reeds instead of silver layers as contacts.

Key switches are divided into two categories: key switches with metal reeds as switch contacts, which have good feel, low contact resistance and "tick" sound. Switches that use conductive rubber as contact paths are usually called conductive rubber switches. The switch feels good, but the contact resistance is large, generally between 100 and 300n. The structure of the key is that the key moves downward, so that the contact reed or conductive rubber block contacts the pad to form a path.

The operating force of the key switch is related to the state of the reed. At first, the force is proportional to the compression distance of the reed. When the reed is compressed to 5%-70%, the operating force suddenly decreases, accompanied by a "ticking" sound. There are generally two structures of key switches, and the operating force curve varies greatly with the geometry of the rubber block.

The main uses of key switches are color TVs, black and white TVs, audio equipment, video recorders, cameras, computers, fax machines, intercoms, batons, machine tool control devices, copiers, printers, electronic instruments, meters and other household appliances.