Brief introduction to tantalum electrolytic capacitor


Solid tantalum capacitor was first successively developed by Baylor laboratory in the United States in 1956. It has excellent performance, which is the only product that has small volume and can achieve large capacitance among all the capacitors. It has various shapes and can be easily made into small and sheet type components that are suitable for surface mounting, which can meet the demands of automotive electronic technology and miniaturization development at present. Although tantalum raw material is scarce and tantalum capacitor is expensive, tantalum electrolytic capacitor still develops rapidly and increases its application range as high capacitive tantalum powder (30KuF.g-100KuF.V/g) is largely used and the capacitor manufacturing process is improved. Tantalum capacitor is not only widely used in the military communication, aerospace and other fields, but also largely used in the industrial control, video equipment, communication instrument and other products.

Tantalum electrolytic capacitor which is produced currently mainly includes sintered solid, foil-shaped winding solid and sintered liquid. Among them, the sintered solid occupies about more than 95 percents of total production at present, which is mainly packaged in resin encapsulation method. With the ascendant technology that combines miniaturization, chip-based technology and SMT technology, chip sintered tantalum capacitor has gradually become the mainstream.

Solid tantalum capacitor has good electrical property, wide operating temperature range and excellent volumetric efficiency. Besides, its unique characteristics are as follows:

The working medium of tantalum capacitor is a layer of paper-thin tantalum pentoxide film that is generated on the surface of metal tantalum. This kind of oxide film layer is completely combined with one of the capacitor terminals and cannot exist individually, thus it will have particularly large capacitance in unit volume, which means that it has very high specific capacity and is especially suitable for miniaturization.

In the working process of tantalum capacitor, it can automatically repair or isolate the defect of oxide film, thus it can ensure that the oxide film medium will be reinforced and restore its insulating ability at any time instead of suffering continuous cumulative damage. Due to its unique self-healing performance, it will have long service life and good reliability.

Tantalum electrolytic capacitor has very high electric field strength, which is higher than any type of capacitor. Therefore, its miniaturization can be realized.

Tantalum electrolytic capacitor is very easy to obtain large capacitance, which is superior to other capacitors when used in the power smoothing and AC bypass.

Tantalum capacitor has unilateral conductivity, which is so called “polarity”. When used, it should be accessed into the current according to the positive and negative direction of the power, in which the anode (positive pole) of capacitor is connected to “+”pole of the power, while the capacitor cathode (negative pole) is connected to the “-“pole of the power; if it is wrongly connected, the capacitor cannot play its effect and will lead to electric leakage at the same time. Within a short time, the capacitor slug will release heat, destroy the oxide film and lose its effect immediately.

Although the working voltage has a certain upper limit value, it will not influence on the cooperation with the translator or the integrated circuit power. Electrolytic capacitor is usually considered to be a kind of electronic component that has good performance and long service life, ordinary, its failure rate can reach 7 levels. However, it is still conforms to the failure universal rule of electronic components, which is called bathtub failure curve. As its early failure can be removed in the ageing process, it will only lose efficacy in random.