1. Characteristics, Applications and Classification of Membrane Switches 1. Characteristics As we all know, switches in electronic products play a role in transmitting command information. There are many types of switches, and their development is constantly updated with the advancement of electronic machine products. In the 1950s, the toggle Switch of the struggling component was used to toggle the switch, and the changeover switch dominated; in the 1960s, a combination switch represented by a key switch was introduced to accomplish a simple function conversion; as the application field expanded and the function of the whole machine increased. In the 1970s, there was a switch of conductive rubber. The switch was a new type of electronic device that was developed in the late 1970s and early 1980s. It was a miniaturization and digitization of products conforming to the electronics industry. Intelligent, multi-functional development needs products.
The Membrane Switch is a switch made by printing a contact circuit with a conductive paste on a flexible polycarbonate or a polyester film and is a type of contact switch.
Membrane switch is a flat type, multi-layer combination, and a sealed structure. It is an assembly of an electronic whole machine operating system that incorporates key switches, panel function marks, readings display transparent windows, indicator window holes and circuits.
It has the following features:
(1) The durability of the durable membrane switch can generally reach more than one million times. The reason for such long life is that the action of the switch is only achieved by the elastic membrane in the vertical direction. Although the elastic film has been previsualized by millions of times, the creep range is only 0.1 to 0.3 mm (both switching strokes), and the material selection is far from the yield limit of the film. Can withstand more than one million lives without deformation. On the other hand, the contact of the switch is vertical, and the amount of wear is very small; the Screen -printed contacts can form a sufficient thickness, and a layer of conductive carbon is added on the silver paste contacts to achieve high Wear-resistant, self-lubricating purpose, so the life of the membrane switch is more than a dozen times more than the mechanical contact switch.
(2) Good sealing performance Because the membrane switch is an overall hermetic structure, the contacts of the switch are not eroded by harmful gases and are not easily oxidized. The waterproof and dustproof features make the contacts of the switch more suitable for various harsh environments.
(3) Small size, light weight and reliable structure the membrane switch can be arranged and assembled into a Membrane Keyboard in design, and its arrangement density is high, and it is a sealed sheet structure formed by a combination of multiple layers of membranes, and the connection between all the switches. The lines and leads are completed by screen printing at one time, with a total thickness of 1 to 3mm, thus reducing the volume, reducing the quality and improving the reliability.
(4) Rich color and beautiful appearance Membrane switch can be personalized according to the user's design concept in the design of the color pattern. The decorative effect reflects the comprehensive characteristics of material beauty, decorative beauty, and craft beauty.
(5) Reducing the cost of supporting electromechanical products Traditional mechanical switches require welding during installation, even with fixed brackets. The membrane switch is installed as a paste type, as long as the adhesive paper is peeled off, it can be firmly stuck on the surface of the whole machine, and the lead outlet of the membrane switch is inserted into the socket of the rear circuit of the complete machine, and the circuit can be connected in an instant. Provincial workers, provincial materials, reduce the overall cost of the machine.
2. The application of a membrane switch is a non-trivial switch. Suitable for switching power less than 1W ah, maximum operating voltage: 42V (DC) or 25V (DC), maximum operating current is less than 100mA working. Can be widely used in all microcomputers, CNC. Intelligent instruments | Meters, meters, and electronic circuits that combine discrimination and memory functions.
3. Classification of Membrane Switches Membrane switches can be classified according to the two characteristics of the environment or circuit substrate. According to the environmental classification can be divided into reward film switch and military membrane switch two categories; if the circuit substrate, that is, according to the circuit formation can be divided into conductive printed circuit and copper foil etching circuit two major categories of membrane switch.
(1) Commercial membrane switch was released on July 1, 1991, and the assessment standards for high, low temperature, constant moist heat, and temperature change of membrane switch in the mechanical industry standard JB5045-91 of the People's Republic of China in 1992 were implemented. for:
High temperature: (55+/-2) degrees (72h)
Low temperature: (-40+/-3) degrees (16h)
Constant heat and humidity: (40+/-2) degrees {Relative humidity 96% +/- (2-3%), duration 96h}
Temperature change: -40 to 50 degrees (after 2 cycles of 5 cycles, 2 hours recovery under normal atmospheric conditions
Any membrane switch that can pass this type of assessment and has the general function of a membrane switch can usually be called a commercial membrane switch. It is the most common membrane switching device featured in a membrane switch.
The panel layer of a commercial membrane switch is usually a PC or PET film as a substrate, the circuit substrate is a conductive silver paste, or a conductive silver carbon paste slurry; the conductive print carrier is a PET film. Due to the application environment and the reduction of manufacturing cost, the separator is usually made of an inexpensive PVC film.
(2) The biggest difference between the two types of military membrane switches is the use of different environments, and the use of military membrane switches is rather harsh. As far as the ambient temperature is concerned, its operating conditions not only need to meet -54 to 70 degrees, but it also needs to receive a temperature shock of -55 to 100 degrees for three cycles. Moreover, in foreign military standards, the high temperature test specifies a working temperature of 125 degrees and a high temperature storage temperature of 150 degrees. It is clear that commercial membrane switches are not suitable for working in such a harsh military environment.
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