Structure principle and performance of tantalum capacitor

Tantalum capacitors were first developed in 1956 by baylor laboratories in the United States. With excellent performance, tantalum capacitors are small in size among all capacitors and can reach a large capacity. Tantalum capacitors come in a wide variety of shapes and are easy to be made into small and sheet elements suitable for surface mount. It is suitable for the development of electronic technology automation and miniaturization. Although tantalum raw materials are scarce and tantalum capacitors are expensive, tantalum capacitors have been rapidly developed and widely used due to the large number of tantalum powder with high specific capacity (30kuf.g-100kuf.v /g) and the improvement and perfection of capacitor manufacturing process. Tantalum capacitors are widely used not only in military communication, aerospace and other fields, but also in industrial control, film and television equipment, communication instruments and other products.

At present, tantalum capacitors mainly include sintered solid, foil winding solid and sintered liquid, among which sintered solid accounts for more than 95% of the total production volume, and non-metallic sealed resin encapsulation is the main body. Miniaturization, chip type and SMT technology are in the ascendant, chip sintered tantalum capacitors have gradually become the mainstream.

Solid tantalum capacitors are characterized by excellent electrical performance, wide operating temperature range, diverse forms, excellent volume efficiency and unique features:

The working medium of tantalum capacitor is a very thin tantalum pentoxide film formed on the surface of tantalum metal.

The oxide film dielectric of this layer is completely integrated with the pole of one end of the capacitor and cannot exist alone. Therefore, the electrical capacity per unit volume is particularly large. That is, the specific capacity is very high, so it is particularly suitable for miniaturization.

In the working process of tantalum capacitor, it has the performance of automatically repairing or isolating the defects in the oxide film, so that the oxide film medium can be strengthened and restored at any time without being damaged by continuous accumulation. This unique self-healing performance ensures its long life and reliability advantages.

Tantalum electrolytic capacitor has a very high working electric field intensity and is larger than any other type of capacitor, so as to ensure its miniaturization.

Tantalum capacitors are very convenient for obtaining large capacitance and have few competitors in power filtering, ac bypass and other applications.

Unidirectional conductivity, that is, the so-called "polarity", the application should be in accordance with the positive and negative direction of the power supply access current, capacitor anode (positive pole) connected to the power supply "+" pole, cathode (negative pole) connected to the power supply "-" pole; If the capacitor is not connected properly, and the leakage current is large, the core will be heated in a short time and the oxide film will be damaged and then fail.

The operating voltage has a certain upper limit, but this disadvantage is not important for matching transistor or integrated circuit power supply.

Electrolytic capacitor is generally considered to be a good performance, long service life of electronic components, its failure efficiency can reach seven levels when normal. However, it always conforms to the general law of failure of electronic components, that is, bathtub-shaped failure curve, early failure can be eliminated in the old refining process. So there's only a chance of random failure. And this kind of invalidity has manufacturing technology control problem namely, often accompany a product to be in use process improper or overload be caused by, come to a conclusion about 3 kinds of modes are current type, voltage type and calorific type.

Tantalum capacitors are mainly used for filtering, energy storage and conversion, marking bypass, coupling and decoupling and as time constant elements. Pay attention to its performance characteristics in the application, the correct use will help to give full play to its functions, such as considering the working environment of the product and its heating temperature, as well as taking measures such as reducing the amount of use, if the use of improper will affect the working life of the product.