Among capacitors, tantalum capacitor is a product with small volume and high capacitance. Tantalum capacitors are made of tantalum metal with tantalum as the anode, a layer of oxide as the dielectric, and a surrounding conductive cathode.
Tantalum capacitors offer excellent performance, come in a variety of shapes, and are manufactured as small and chip components suitable for surface mounting. Tantalum capacitors are not only used in aerospace and other fields, but also widely used in industrial control, video equipment, communication instruments, automobiles and other electronic equipment.
Advantages of Tantalum Capacitors
The full name of tantalum capacitor is tantalum electrolytic capacitor, which is a kind of electrolytic capacitor. It uses metal tantalum as the medium. itself has almost no inductance.
The dielectric layer of tantalum capacitors is formed by oxidation of the anode metal in the electrolyte, and the resulting dielectric film generates heat under the action of an applied voltage, which easily produces oxides with high resistivity. This is equivalent to repairing defects such as defects and cracks in the oxide film, and in simple terms, it has a self-healing effect. This unique self-healing property ensures its advantages of long life and reliability.
Solid tantalum capacitors have excellent electrical properties, wide operating temperature range, various forms, and excellent volume efficiency. They have unique characteristics: the working medium of tantalum capacitors is a very thin layer of tantalum pentoxide film formed on the surface of tantalum metal. This layer of oxide film dielectric is combined with one end of the capacitor and cannot exist alone. Since the anode block has a lot of microporous structures, it has a particularly large capacitance per unit volume, that is, a high specific capacity, so it is suitable for miniaturized circuit boards.
Disadvantages of Tantalum Capacitors
Tantalum capacitors are more expensive than aluminum electrolytic capacitors with the same capacity and withstand voltage, and their withstand voltage and current capabilities are weaker. It is used in large-capacity filtering or rectification, but due to its ability to withstand voltage and current, tantalum capacitors will not appear near the CPU socket.
At present, common tantalum capacitors have three failure modes: voltage type, current type and heating type, which are prone to burst and burn after failure, which limits its application in fire and explosion-proof scenarios.
Filter performance
Tantalum capacitors have excellent performance. They are small in size and can achieve large capacitance among capacitors. They play a huge role in power filtering, AC bypass and other applications.
Tantalum electrolytic capacitors have the functions of storing electricity, charging and discharging, and are mainly used in filtering, energy storage and conversion, number bypass, coupling and decoupling, and as time constant components.
Pay attention to its performance characteristics in the application, correct use will help to give full play to its functions, such as considering the working environment of the product and its heating temperature, and taking measures such as derating use, if used improperly, it will affect the working life of the product.
During the working process of tantalum capacitors, it has the function of automatically repairing or isolating the defects in the oxide film, so that the oxide film medium can be strengthened at any time and restore its proper insulation ability without continuous cumulative damage. This unique self-healing property ensures its advantages of long life and reliability.
Chip Tantalum Capacitors
Surface mount tantalum capacitors are frequently used in modern electronics where they enhance reliable service and allow high capacitance values to be achieved in the small package sizes required by modern equipment.
Aluminum electrolytes were not initially available in surface mount packages due to their inability to withstand the temperatures required for soldering. Therefore, tantalum capacitors that can withstand the soldering process are almost the only choice for high-value capacitors in surface mount assemblies. Although surface mount electrolytes are available, tantalum remains the preferred choice for chip capacitors due to its favorable cost, size and performance parameters.
The difference between tantalum capacitors and ceramic capacitors
The materials of this kind of capacitor are different. Tantalum capacitors use tantalum as the medium, and ceramic capacitors use ceramics as the medium.
The capacitance of ceramic capacitors is much smaller than that of tantalum capacitors. Tantalum electrolytic capacitors can achieve small capacities, while ceramic capacitors with large capacities are difficult to achieve ideal performance. Most of the physical properties of tantalum capacitors are better than ceramic capacitors.
The uses of the two are also different: tantalum capacitors can be used as coupling, filter oscillation bypass and other circuits with a wide operating frequency range, while ceramic capacitors are mostly used in high-frequency circuits.
The difference between tantalum capacitors and ceramic capacitors is that under the same capacity, tantalum capacitors are much smaller in size, and tantalum capacitors have lower ESR than electrolytic capacitors, longer life, and high temperature resistance. However, since the main material of tantalum capacitors is tantalum, this metal is very expensive, so the price of tantalum capacitors is also very expensive, and generally only high-end products that are not sensitive to prices will be used.
Moreover, the capacity of ceramic capacitors is generally not large, and they are generally used in conjunction with electrolytic capacitors, and they are often used as decoupling. Ceramic capacitors are also relatively cheap capacitors. The ceramic capacitors inserted directly into wafers are the cheapest, and many low-end home appliances use them.
Multilayer ceramic capacitors are now the most widely used and can be used in almost all electronic products. In recent years, with the continuous advancement of technology, the capacity of ceramic capacitors has become larger and larger. There have been 47UF multilayer ceramic capacitors. Large-capacity ceramic capacitors are gradually replacing tantalum capacitors, but now there are only a few large-capacity ceramic capacitors in Japan. Only big brands can do it, so the price is still a bit more expensive, about the same price as tantalum capacitors.
In addition, there are several differences between tantalum capacitors and ceramic capacitors in terms of performance:
Ageing:
The aging of a capacitor is the logarithmic decrease in capacitance over time. Tantalum capacitors do not age, and there is no known wear mechanism for tantalum capacitors, whereas ceramic capacitors do.
polarization:
Most tantalum capacitors are polarized, meaning they can only be connected to a DC supply while maintaining proper terminal polarity. Non-polarized ceramic capacitors can be safely connected to AC mains. Ceramic capacitors have a higher frequency response because they are not polarized.
Temperature response:
Tantalum capacitors have a linear capacitance change over temperature, while ceramic capacitors have a nonlinear response. Ceramic capacitors can achieve linear trend by reducing the operating temperature range and considering the temperature response during the design stage.
Voltage response:
The capacitance of tantalum capacitors changes significantly with the applied voltage, while ceramic capacitors do not. The dielectric constant within a ceramic capacitor shrinks as the applied voltage increases, causing a change in capacitance. While the change in capacitance of most ceramic capacitors is linear, some high-permittivity dielectrics lose 70% of their initial capacitance when operated at rated voltage.
