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Capacitors are the most widely used, with the largest amount, and can not be replaced by electronic components, the output of about 40% of the electronic components, while the aluminum electrolytic capacitors (three) of the major categories of capacitors (electrolytic capacitors, ceramic capacitors, organic film capacitors) output 36.8%. Electrolytic capacitor is one of the most rapidly developing components in our country in 10 years. At present, the annual production of electrolytic capacitors is close to 25000000000, and the annual average growth rate is 28%, which accounts for 1/3 of the output of electrolytic capacitors. In the development process, the aluminum electrolytic capacitor also comes from the integrated circuit, the whole machine circuit and the other capacitor in the field of high voltage, high frequency, long life and small capacity. Aluminum electrolytic capacitor itself is constantly improving, improving and innovation. Especially with the development of science and technology, the improvement of the social demand, the improvement of the environment, the birth of the new type of machine, the application field of small scale, chip and high voltage and large capacity aluminum electrolytic capacitor is widening. Therefore, the aluminum electrolytic capacitor not only will not shrink, but also has a stronger vitality and a wider space for development, there will be a faster growth rate.
Aluminum electrolytic capacitor structure and performance characteristics of aluminum electrolytic capacitor device by after corrosion and formation of the anodic oxide film of aluminum foil, after corrosion of the cathode aluminum foil, intermediate across the electrolytic paper rolls around, then soaked in the electrolyte and then sealed in aluminum shell made of. Its performance characteristics are as follows.
1.1 unit volume power capacity is very large
Capacitor capacitance C = epsilon 0 epsilon rS/d. Among them, and epsilon 0 is the vacuum Permittivity (constant), epsilon R is the relative permittivity of dielectric materials, and S is the effective electrode area, D is the thickness of the dielectric material. For aluminum electrolytic capacitor, epsilon r=8 ~ 10. The anode aluminum foil and the cathode foil can be increased by corrosion to several times to hundreds of times. D= alpha Vf, alpha = 1.4nm/V, Vf=10V ~ 600V, D is about 0.014 m ~ 0.9 m, than the other capacitor several times to hundreds of times. Therefore, the electrolytic capacitor of the unit volume capacity than other capacitors, a few times to several times.
1.2 rated capacity is very large due to the use of electrolytic capacitors winding structure, it is easy to expand the volume, therefore, can be easily done tens of thousands of micro or even hundreds of thousands of micro method of rated capacity.
1.3 with self-healing effect due to the electrolyte inside the capacitor. Therefore, in work, dielectric capacitor anode aluminum foil in the event of local failure, electrolyte O2 or - or radical ion under the action of electric field force quickly arrived at the damage location, will undermine the position of the clog up, and will damage the film repair, the capacitor to return to a normal state.
1.4 high electric field strength due to the anodic oxide film during the formation of about 1.4nm, that is, the electric field intensity of the anodic film is about 7 * 107V/cm, the electric field intensity of the electric field is about 5 * 107V/cm, which is much higher than the electric field strength of the ceramic capacitor and thin film.
1.5 price advantage due to the main raw materials used in the manufacture of aluminum electrolytic capacitors are common industrial materials, the equipment used in general industrial equipment, automation is also higher, so manufacturing costs are relatively low, especially the manufacturing cost of the unit capacity than other types of capacitors has an overwhelming advantage.
2 aluminum electrolytic capacitors
2.1 polarity and leakage of the possibility of leakage due to the presence of the electrolytic capacitor, the use of positive and negative electrode must pay attention to the correct method, otherwise not only can not play a role, and leakage current is very large, short time capacitor will heat, damage the oxide film, with damage. Aluminum electrolytic capacitor with aluminum shell and rubber seal, when the working electrolyte is heated vaporization, easy to get from the root of the lead. After a long period of time in the capacitor, the electrolyte is dry, so that the capacitor is invalid. This is one of the main failure modes of aluminum electrolytic capacitor.
2.2 loss angle tangent value larger, temperature and frequency characteristics of relative poor working electrolyte in aluminum electrolytic capacitor plays a role of cathode, due to the working electrolyte is an ionic conductor, and the velocity of ions than the velocity of the electrons much slower, resulting in working electrolyte conductivity is lower than that of the conductivity of the electronic conductor. Dipped and electrolytic paper, a further decline in the conductivity. Therefore, working electrolyte caused by the equivalent series resistance ratio caused by the metal electrodes of the other capacitor equivalent series resistance is large, resulting in aluminum electrolytic capacitor loss angle tangent value is larger, and the frequency characteristics of relatively poor. In addition, the temperature characteristics of the aluminum electrolytic capacitor are relatively poor due to the temperature of the electrical conductivity of the liquid material.
2.3 Aging Working Electrolyte despite the weak acid and weak base salt as electrolyte, water and organic solvent as the solvent, but still has certain corrosion, the capacitor anodic oxide film and a rubber stopper has a certain erosion. In addition, there is a certain chemical reaction between the salt and the solvent. These phenomena will lead to the deterioration of the electrical performance of the capacitor. In short, although the aluminum electrolytic capacitor has some disadvantages, it limits its application in some occasions, but because of its high capacity and price advantage, it has a significant advantage in the competition of ceramic capacitors, film capacitors, tantalum electrolytic capacitors.
