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SMD aluminum electrolytic capacitors are also known as chip capacitors, commonly used are multi-layer ceramic capacitors, high-frequency cylindrical capacitors, chip-like polyester capacitors, chip-like electrolytic capacitors, chip-like tantalum electrolytic capacitors, chip-like micro-adjustable capacitors and so on. It is widely used in circuit design. This paper introduces some matters needing attention in the use of chip capacitors. Flake capacitor is also called chip capacitor, commonly used are multi-layer ceramic capacitor, high-frequency cylindrical capacitor, chip-like polyester capacitor, chip-like electrolytic capacitor, chip-like tantalum electrolytic capacitor, chip-like fine-tuning capacitor and so on. Attention should be paid to the use of flake capacitors. (1) the working voltage of the capacitor must be lower than the rated voltage and should not exceed the rated voltage. For example, when the working voltage is 12V, the rated voltage is 16-25V; when the working voltage is 5V, the rated voltage is 6-10V; when the working voltage is 3.3V, the rated voltage is 4-6V. In addition, the capacitance of the capacitor is also related to the voltage value. For example, the flake tantalum capacitor withstands voltage 4-50V, 0.1-4.7uF small capacity capacitor has rated voltage of 50V, and 10 pF above, withstand voltage value higher than 25V is rarely seen. Therefore, attention should be paid to circuit design. (2) chip capacitors can replace small voltages with large voltages. For example, the circuit needs a 10V 1UF capacitor, which can be replaced by the 1UF capacitor of 16V. (3) capacitor accuracy and material category should be chosen reasonably. The accuracy of commercial chip capacitors below 0.01 uF can reach J (+5%); above 0.01 uF, J class is less, with K class (+lO%) more; above 0.1 uF, M class (+20%) more. (4) The capacity specifications (series) of the chip capacitors with size code 0805 are the most complete on the market, and some of the capacity of 0603 may be out of stock. When the production lot size is small, in order to prevent the shortage of the market and affect production, the pad can be slightly extended, so that it can be applied to 0603 and 0805, to avoid the absence of parts and stop production. (5) Flaky multi-layer ceramic capacitors are all rolled-in, the type is on the tape disc, and there is no sign on the capacitor. Although the capacity can be measured by measuring methods, it is difficult to distinguish the accuracy grade of material categories. Therefore, be careful when using it, especially manual assembly. (6) Open-type slice-type fine-tuning capacitor can not be welded by wave soldering, but closed-type slice-type fine-tuning capacitor can be welded by wave soldering. (7) Lamellar capacitors are generally multi-layer structure, some people use soldering iron manual welding, at this time must pay attention to the welding speed, avoid overheating, resulting in a large temperature difference and fracture of the base end, so that capacity decline. (8) chip capacitors are made of ceramic substrates, thin and crisp. Some of the circuit boards are thin, and the force will be deformed when they are installed, which will easily cause the capacitor to break. Solution: In addition to improving the design process, can also easily cause breakage in places where the use of tubular capacitor, because the strength of tubular capacitor is high, not easy to break

The capacitor is interrupted in the electrified circuit. The capacitor stores a certain amount of voltage. When there are other loads or components in the circuit, it will discharge slowly. It can also discharge quickly by artificial short circuit with small resistance or conductor (low voltage). How to operate it? Let's show you the following: 1. Lead-type small specifications of aluminum electrolytic capacitors, direct short-circuit discharge on the line, but generally we do not recommend. 2. The electrolytic capacitor with a slightly larger capacity can make a 220v/60-100w bulb or discharge slowly with a resistor. 3. Bolted high-voltage large-capacity electrolytic capacitors we recommend the use of discharge coils, not only can discharge all capacitors of electricity, but also in the repair of short-circuit fault is a good helper. Remember, large electrolytic capacitors must not be short-circuit discharged directly, otherwise the instantaneous energy is infinite, the sparks are quite dazzling, the noise is as loud as the shells, hehe, it's not to frighten you, I tried, it's frightening, and life threatening. Our recommendation is that all capacitors use discharge coils, which are safe and do not harm people or equipment. There is a very simple way to find a short wire, about 5m, winding up, two crocodile clamps, directly connected to the capacitor cathode, you can discharge. But remember one thing: first, the wires should not be too short, and two must be wound up. Especially when the aluminum electrolytic capacitors with high voltage and large capacity are discharged, you will find that the wires are hot.

In identifying the use and installation environment, capacitors used within the rated performance range specified in the product sample design specification should be avoided in the following cases: 1.high temperature (temperature exceeds maximum usage temperature). 2. Over-current (current exceeds rated ripple current), when applied ripple current exceeds rated value, the capacitor body will be overheated, the capacity will be reduced, and the life will be shortened. 3. Overvoltage (voltage over rated voltage), when the applied voltage on the patch capacitor is higher than the rated working voltage, the leakage current of the capacitor will rise, and its electro-oxygen properties will deteriorate in a short time until damage; 4. Applying the reverse voltage or alternating current voltage, when the DC aluminum electrolytic capacitor is connected to the circuit according to the reverse polarity, the capacitor will lead to short circuit of the electronic circuit, and the resulting current will cause damage to the capacitor. If a positive voltage is applied to the negative lead in the circuit, a nonpolar capacitor is selected. 5. The service life of the circuit which is used for repeated and rapid charging and discharging, such as fast charging, may be reduced because of the decrease of capacity and the sharp rise of temperature. 6. Capacitors are forbidden to be used in harsh environments where water, salt water, oil or dew are directly in contact with, or are full of harmful gases (sulfides, ammonia, etc.), direct sunlight, ozone, ultraviolet radiation and radioactive substances, vibration and shock conditions exceed the limits specified in the samples and instructions.

The selection of chip capacitors involves many problems. The first is the problem of withstanding voltage. If the voltage at both ends of a patch capacitor exceeds its rated voltage, the patch capacitor will be damaged by breakdown. Generally, the withstand voltage of electrolytic capacitors is 6.3V, 10V, 16V, 25V, 50V and so on. The ability of different patch capacitors to store charges is also different. The amount of charge stored when a chip capacitor is applied with 1 volt DC voltage is called the capacitance of the chip capacitor. The basic unit of capacitance is Fala (F). But in fact, Farad is a very unusual unit, because the capacitance of the patch capacitor is often much smaller than 1 Farad, commonly used micro method (mu F), nano method (nF), skin method (pF) (skin method also known as micro micro method), their relationship is: 1 Farad (F) = 1000000 micro method (mu F) = 1000 nano micro method (nF) = 1000000 skin method (pF) Various kinds of chip capacitors are needed in electronic fabrication, and they play different roles in circuits. Similar to resistors, they are usually referred to as capacitors and are represented by letter C. Chip capacitors, as the name implies, are containers for storing electric charges. Although there are many kinds of patch capacitors, their basic structure and principle are the same. A patch capacitor is formed when two pieces of metal are separated from each other by a substance (solid, gas, or liquid). The two metal is called the polar plate, and the intermediate substance is called the medium. The chip capacitor is also divided into fixed capacity and variable capacity. But the most common ones are fixed capacity capacitors. The most common are electrolytic capacitors and porcelain capacitors.

The construction and production process of tantalum capacitors The solid tantalum electrolysis consists of tantalum powder (positive electrode) + oxide film (independent of tantalum powder) + manganese dioxide + silver powder + graphite + epoxy resin + lead The first step: the tantalum powder and organic solvents are mixed together and pressed to form according to a certain shape, and the tantalum lead is embedded at the same time. Step 2: The tantalum powders doped with organic solvents were sintered in a vacuum to a sponge-like state at high temperatures above 2000 degrees, and The leads really fuse together. Step 3: The spongy tantalum is electrolyzed in a solution of phosphoric acid, and the surface is oxidized to form tantalum pentoxide. The dielectric constant of five oxidized tantalum two is very high. About 27, the performance of the three oxidation two aluminum medium (dielectric constant 7) is higher than that of the aluminum electrolytic capacitor. Step 4: The liquid manganese nitrate is added to the tantalum block and then decomposed into manganese dioxide and nitrogen dioxide by thermal decomposition in the water vapor (catalyst) environment. Manganese nitrate adsorbs well, and the resulting manganese dioxide can be completely adsorbed in the innumerable pores of the surface tantalum block. If we use the two oxidation of the solid directly here Manganese, it can not achieve this effect, which is why manganese dioxide can only be obtained in the manufacturing process. If solid polymers such as PPY/PEDT are used, Its melting point is very low, so it can be melted and put into it directly. Step 5: Finally, silver powder and graphite should be coated on the surface of manganese dioxide to reduce its ESR and enhance its conductivity.