Classification
Semi-conductive film
Semi-conductive film only has semi-insulating polysilicon film. Semiconductor thin films mainly include epitaxially grown Si single crystal thin films, CVD grown doped polysilicon thin films, and semi-insulating polysilicon thin films. Insulator films mainly include silicon oxide films and silicon nitride films. Metal thin films mainly include Al, Au, NiCr and other thin films. The thin film technology photoresist film used in the process.
and membrane keyboard
The base material of the circuit should be made of polyester (polyethylene phthalate) film (Potyester, referred to as PET). It has good insulation and heat resistance, high mechanical strength, transparency and air tightness, especially bending resistance and high elasticity. It is an ideal material for making membrane keyboard circuits.
Material
Type
The material of membrane keyboard and panel, in addition to flatness and printing adaptability, is more importantly flexible And the characteristics of high flexibility.
Polyvinyl chloride PVC is stable to acids, alkalis and salts at room temperature. Good abrasion resistance, flame resistance and self-extinguishing, noise reduction and shock absorption, and good electrical insulation. Poor thermal stability. Low-cost ordinary signs, panel polycarbonate PC glossy surface has high light transmittance, low water absorption, good dimensional stability, excellent bending, tensile, and compressive strength, heat resistance, cold resistance, electrical insulation, and atmospheric aging resistance Excellent sex. The resistance to chemicals is poor, fatigue resistance is poor, and stress cracking is easy to occur. The output interface terminal circuit is generally printed with carbon material and has no protective coating. It will gradually form a peeling layer due to air oxidation, which will eventually cause a circuit breaker. End of life, this is the most prone to failure of the membrane keyboard, mainly determined by the environment, no matter whether it is used or not, the physical damage time is 3-10 years. Generally, the scope of application is the widest. In addition to meeting the requirements of most membrane keyboard panels, the high light transmittance of glossy PC can also meet the requirements of LCD windows.
Polyester smooth surface has good chemical resistance, is insoluble in general organic solvents, and is not resistant to alkalis. It has excellent mechanical properties, electrical properties, rigidity, hardness and the greatest toughness among thermoplastics, low water absorption, excellent wear resistance and friction resistance, and high dimensional stability. The tensile strength is comparable to that of aluminum film, much higher than that of PC and PVC. Inexpensive Because the surface is difficult to process into a matte type, textured PET is more expensive. It is the most ideal substrate for making membrane keyboard circuits. Among them, textured PET is suitable for products with higher surface requirements or liquid crystal display windows.
Thickness
Plastic substrate thickness of 0.25mm and below is called film, which is mainly used as the panel layer of membrane keyboard, and various indicative patterns and texts are printed on the back of it. Indicates the operating area of the corresponding switch key position. The thickness selection should depend on the size of the panel and the button. The material is thick, the touch force is increased, and the response is slow; the material is too thin, the hand feels bad when touched, and the rebound is not obvious. The thickness of 0.25mm or more is called a plate, which is not suitable for three-dimensional key forming. It can be used as an indicative sign panel for a keyless operation area, and can also be used as a lining board for a membrane keyboard to improve its hardness.
Preparation technology
The following is the preparation technology of transparent conductive film. These technologies can also be used to prepare antistatic film, antirust film, heat shrinkable film, easy-opening film and so on.
Magnetron sputtering
Magnetron sputtering is for high-speed sputtering under low pressure, and the ionization rate of the gas must be effectively increased. A method of increasing the plasma density by introducing a magnetic field on the surface of the target cathode and using the magnetic field to confine the charged particles to increase the sputtering rate.
The sol-gel method
The sol-gel method uses compounds containing highly chemically active components as precursors, mixes these raw materials uniformly in the liquid phase, and performs hydrolysis, The condensation chemical reaction forms a stable transparent sol system in the solution. The sol slowly polymerizes between the aged colloidal particles to form a gel with a three-dimensional network structure. The gel network is filled with solvents that lose fluidity to form a gel. The gel is dried, sintered and solidified to prepare molecular and even nano-substructure materials.
Pulsed laser deposition
Pulsed laser deposition (Pulsed Laser Deposition, PLD), also known as pulsed laser ablation (PLA), is a kind of laser The object is bombarded, and then the bombarded material is deposited on different substrates to obtain a method of precipitation or thin film.
Vacuum evaporation
In a vacuum environment, heating and plating the material on the substrate is called vacuum evaporation, or vacuum coating.
Chemical vapor deposition
Chemical vapor deposition (CVD) is the chemical reaction of reactant substances under gaseous conditions to produce solid substances deposited on the surface of a heated solid substrate. And then the process technology of making solid materials. It is essentially a gaseous mass transfer process in the atom category. The opposite is physical vapor deposition (PVD).