Film materials suitable for making film panel layers, according to their types, we know from the above content that there are often three types: PC, PVC, and PET:
The comprehensive index of physical and chemical properties of PC material is good, and it is suitable for a wide range of inks. It is the most commonly used material for thin film panel layers in Shanghai.
The price of PVC film material is relatively low, about one-half of that of PC material. When producing civilian and popular products, if PVC material is selected, the production cost can be reduced. At the same time, PVC material has good ductility and can be processed by cold pressing. Three-dimensional graphics.
The surface state of the PET film is generally a smooth transparent film, and a few cases also have a sandy surface.
Materials and characteristics of film panels
Membrane buttons of membrane panels occupy most of the market due to their advantages of low cost, simple process and good hand feeling. The buttons used in daily life are basically membrane buttons. The structure of membrane buttons is very simple and can be directly touched. After the upper and lower covers and keycaps, you can see the silicone caps, thin film circuits and circuit boards under the keys.
By looking at the thin-film circuit, it can be found that it is composed of upper, middle and lower layers. The upper and lower layers use conductive paint to print out the circuit. There are corresponding contacts under the buttons, and the middle layer is an isolation layer. The button part is also provided with a circular contact (or hollowed out), and when the keycap is pressed, the connection between the upper and lower circuits is realized and a corresponding signal is generated.
The buttons of the membrane panel button can be divided into two structures: crater and scissor foot (X structure). Among them, the crater structure is the most commonly used design in the button. After the button is inserted into the interface on the button, the bottom is directly in contact with the silicone cap. , the feel is affected by the length of the key column and the elasticity of the silicone cap. The buttons with the crater structure are designed with high key caps and long key travel, so that you can get a good sense of feedback. The disadvantage is that the corresponding body needs to be well-made. It is thicker, and the stability of the keys is slightly poor, and it is easy to shake, so you can't get a very consistent feel when clicking. The substrates suitable for making membrane switch panels include PC, PVC, PET, etc.:
Polycarbonate film (PC)
PC material can be divided into sand surface and glossy surface. The comprehensive index of physical and chemical properties of PC material is better, and it is suitable for a wide range of inks. It is the most commonly used material for thin film panel layers in Shanghai. The polycarbonate film has a wide temperature range (-135~135°C). When the temperature or humidity changes, the performance of this material does not change much, thus ensuring that the panel can be used in various instruments and various harsh environments. . However, its disadvantage is that it is more sensitive to solvents, and solvents with strong solvation effect are easy to make it embrittled and cracked.
Polyvinyl chloride film (PVC)
The price of PVC film material is relatively low, about one-half of that of PC material. When producing civilian and popular products, if PVC material is selected, the production cost can be reduced. At the same time, PVC material has good ductility and can be processed by cold pressing. Three-dimensional graphics. The temperature resistance of polyvinyl chloride film is poor, especially under high temperature conditions, its softening temperature is 59 ℃, and its elasticity is not as good as that of polycarbonate film. But it has a high elongation (130%), and because of its low price, it is suitable for use under normal conditions.
Polyester film (PET)
The surface state of the PET film is generally a smooth transparent film, and in a few cases, there are also products with a sandy surface, such as the KB product of Japan's Kimoto Company. Polyester film has better elasticity and temperature resistance, and its price is between polycarbonate film and polyvinyl chloride film. However, because the surface of the film is difficult to process into a matte texture, most of them are transparent sheets. At the same time, the surface of the polyester film cannot obtain satisfactory printing effects for most plastic inks. Generally, specific special inks are required. Ensure good subsequent processing performance. Because the general performance of PET film can be replaced by PC film, so there are not too many cases for Shanghai film panel materials, unless in some special occasions, such as insulation, resilience, solvent resistance, etc., other films cannot There are only a small number of applications when it is satisfied.
The main type of membrane switch membrane switch panel is a rigid or flexible printed circuit board as the substrate, the device has a feel or no feel, and then covered with printed colorful decorative material Shanghai film panel, which integrates switch functions and The electronic component with decorative function is a new type of human body dialogue interface, and the connection method between the switch circuit and the whole machine can be completed by welding or plugging.
What factors should be considered in the selection of film panels
There are many processing methods for film panels, but most of them use printing technology on raw materials to print some exquisite patterns and signs required by customers. The most important thing is to play a decorative role, and it is still on the surface, so it must remain undamaged for a long time. Because printing has requirements for materials, not all film materials are suitable for ink printing. The film material should not be too thin, because the surface cannot be flattened when the material is too thin to print, which will affect the printing effect. It is also necessary to ensure that the material is suitable for most of the inks on the market. Different ink manufacturers have different processes, so the quality cannot be guaranteed to be the same.
The film panel is mainly for aesthetics and decoration, so the transparency of the material is very important. At least a transparency of more than 90% must be achieved. Only such materials can be used as materials for film panels, and they must also be able to resist high temperature, sunscreen, waterproof, and friction for a long time. Membrane panels and membrane buttons are used in a wide range of applications, and each area must have different characteristics. For example, large-scale high-temperature machinery requires high-temperature resistance, and outdoor decorations require sunscreen and waterproof features.
In the same membrane switch, the size of the metal shrapnel below is generally the same, but the button area on the panel layer is different in size. In such a situation, some problems are prone to occur. Since the size of the metal shrapnel of the button is limited, the problem of inaccurate buttons will appear. But how can we avoid this and solve these problems in the process of production and production?
First of all, because the size of the metal shrapnel is limited, but the drawings provided by our customers are different, and the size of the button display area on the drawings is not the same. Generally speaking? In the same product, only Using the same type of metal shrapnel, such an operator has no way to accurately find the position of the lower metal shrapnel during the operation, and cannot make the current of the lower conductive layer complete the return flow of the circuit, and form a current order. instruction.
During the installation process of the film panel, the center point of the metal shrapnel must be aligned with the center point of the conductive circuit, and it must be fixed. The letters on the button display area of the panel layer are generally abbreviated in order to save space, and their size is generally no larger than twice the size of the lower metal shrapnel. If it is too large, the balance force will be lost, and the precise position of the metal shrapnel cannot be found during the operation.
Types and Structures of Membrane Switch Panels
1. Flat non-touch type: service life of about 300,000 times, but no touch (affected by the use environment).
2. Shanghai membrane switch panel bulging touch and pressing type: it has a good touch, but its service life is relatively short, about 300,000-500,000 times (the use environment is affected).
3. Convex frame type non-touch type: beautiful appearance, strong three-dimensional feeling, but no touch feeling (same lifespan as the flat type).
4. The dome type of the key on the membrane switch panel on the surface: the appearance is beautiful, has a strong sense of three-dimensionality, and has a pressing feel of 280g (the life span is more than 600,000 times, and the life span is the longest).
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