Introduction of Capacitor.

Capacitors are wide used in electronic equipement, In any place could be seen capacitors. Now, we make a brief introduction of capacitors for your reference.

    1) Tantalum and Niobium Electrolytic Capacitors: It uses tantalum or niobium as positive, dilute sulfuric acid as negative, oxide film of tantalum or niobium as dielectric. Its features are: small size, large capacity, stable performance, long life, high insulation resistance, good temperature performance, etc., used on high level devices.

    2) Aluminum Electrolytic Capacitors: usually simply called an electrolytic capacitor (e-cap), is a capacitor whose anode (+) consists of pure aluminum foil with an etched surface, covered with a uniformly very thin barrier layer of insulating aluminum oxide which operates as a dielectric. The electrolyte, which covers the rough surface of the oxide layer, operates as the second electrode, the cathode (-). Which is characterized by large capacity, but the leakage, poor stability, there are positive and negative polarity, suitable for power supply filtering or low frequency circuits.

    3) Ceramic capacitor:  is a fixed value capacitor in which ceramic material acts as the dielectric. It is constructed of two or more alternating layers of ceramic and a metal layer acting as the electrodes. Its characteristics: small size, good heat resistance, low loss, high insulation resistance, but the capacity is small, suitable for high frequency circuits. Ferroelectric ceramic capacitors larger capacity, but the larger loss and temperature coefficient for low frequency circuits.
widely used ceramic capacitor has: Chip/SMD Mulitilayer Ceramic Capacitor, High voltage ceramic capacitor, disc radial leads ceramic capacitor, high voltage screw terminal ceramic capacitors.

    4) Mica is a group of natural minerals. Silver mica capacitors are capacitors which use mica as the dielectric. There are two types of mica capacitors: clamped mica capacitors and silver mica capacitors. Clamped mica capacitors are now considered obsolete due to their inferior characteristics. Silver mica capacitors are used instead. They are made by sandwiching mica sheets coated with metal on both sides. This assembly is then encased in epoxy in order to protect it from the environment. Mica capacitors are generally used when the design calls for stable, reliable capacitors of relatively small values. They are low-loss capacitors, which allow them to be used at high frequencies, and their value does not change much over time. Its characteristics are: small dielectric loss, insulation resistance, temperature coefficient is small, suitable for high frequency circuits.

    5) Film capacitor: the same structure as in paper capacitor, the medium is polyester or polystyrene. Polyester film capacitors, high dielectric constant, small size, large capacity, good stability, suitable as bypass capacitors. Polystyrene film capacitors, dielectric loss, insulation resistance, but the temperature coefficient, can be used for high-frequency circuits.

    6) Paper dielectric capacitors: two pieces of metal foil as electrode, sandwiched in thin capacitor paper, rolled into a cylindrical or flat cylindrical core, and then sealed in a metal casing made of an insulating material or shell. It is characterized by smaller, capacity can be made larger. But the inherent inductance and loss is relatively large for low frequency circuits.

    7) Metallized paper dielectric capacitors: structure substantially identical to the paper capacitor, which is covered with a layer of metal film capacitor paper to represent metal foil, small size, large capacity, generally used for low-frequency circuits.

    8) Oil paper capacitor: It is the paper dielectric capacitors immersed in oil through special treatment where, can enhance its tolerant. Which is characterized by large capacity, high pressure, but the larger volume. Moreover, in practice, the first to choose a different type of capacitor for different purposes; the second to take into account the nominal capacity of the capacitor, tolerance, pressure value, leakage resistance, and other technical parameters; the third for the positive and negative polar electrolytic capacitors, the positive and negative electrodes in the welding do not reversed.