Instrumentation analysis The structure and characteristics of commonly used capacitors
Publisher：admin Date：2017-06-13 【Large Medium Small
Capacitors are electronic components commonly used in electronic equipment, the following is a brief introduction to the structure and characteristics of several commonly used capacitors, for your reference.
1, aluminum electrolytic capacitors:
It is made of aluminum cylinder as the negative electrode, which contains a liquid electrolyte, inserted into a bent aluminum strip as the positive electrode. It also needs to be processed by DC voltage to form a layer of oxide film on the piece of positive electrode to do dielectric. Its characteristics are large capacity, but leakage, poor stability, positive and negative polarity, suitable for power supply filtering or low frequency circuit, when used, positive and negative do not reverse.
2, tantalum-niobium electrolytic capacitors:
It is made of tantalum or niobium metal as the positive electrode, with dilute sulfuric acid and other liquid to do the negative electrode, with tantalum or niobium surface generated by the oxide film made of medium. Its characteristics are: large volume filial capacity, stable performance, long life. Insulation resistance is large. Good temperature performance, used in equipment with high requirements.
3、Film capacitor
The structure is similar to paper capacitors, but low-loss plastic materials such as polyester and polystyrene are used as dielectric materials with good frequency characteristics, small dielectric loss, which can not be made into large capacity, and poor heat resistance filters, integration, oscillation and timing circuits.
4、Ceramic dielectric capacitor
Through-core or pillar structure porcelain dielectric capacitor, one of its electrodes is the mounting screw. Lead inductance is very small, good frequency characteristics, small dielectric loss, temperature compensation can not be made into a large capacity, vibration will cause capacity changes, especially for high frequency bypass.
5、Monolithic capacitors
(Multilayer ceramic capacitors) in a number of ceramic film blanks are covered with electrode paddle material, laminated once wound into an inseparable whole, and then sealed with resin outside into a small volume, large capacity, high * and high temperature resistant new capacitors, high dielectric constant of low frequency monolithic capacitors also have stable performance, very small size, high Q capacity error larger noise bypass, filter, integration, oscillation circuit.
6、Paper capacitor
Generally two aluminum foil as the electrode, the middle of the thickness of 0.008 ~ 0.012mm capacitor paper separated by overlapping winding. Manufacturing process is simple, cheap, can get a large capacity; generally in the low-frequency circuit, usually can not be used in the frequency higher than 3 ~ 4MHz. Oil-immersed capacitors have higher withstand voltage than ordinary paper capacitors, and their stability is also good, which is suitable for high-voltage circuits.
7、Trimmer capacitor
The capacitance can be adjusted in a small range and fixed at a certain capacitance value after adjustment. The Q value of porcelain dielectric trimmer capacitor is high and the volume is small, and it is usually divided into two types: round tube type and round piece type.
8、Mica and polystyrene capacitors
Mica and polystyrene dielectric capacitors are usually spring type, simple structure, but the stability is poor.
The wire-wound porcelain dielectric trimmer capacitor is to remove the copper wire (outer electrode) to change the electric capacity, so the capacity can only be small, not suitable for use in the occasion of repeated debugging.