What is a Tantalum Capacitor?Tantalum Capacitors Use,Advantages & Disadvantages

What is a Tantalum Capacitor?

Tantalum capacitors are electrolytic capacitors that use tantalum metal for the anode. They are polarized capacitors with superior frequency and stability characteristics.

What makes tantalum capacitors unique is the usage of tantalum for the anode of the device. This anode is set up as one chunk of material inside of the case, which is very different from the layering style used in MLCC capacitors where the material is sandwiched on itself and then capped on the ends. Using tantalum results in a very thin dielectric layer, resulting in a higher capacitance per volume and allowing for smaller capacitors that can still meet the needs of modern systems. In addition to the nice gain in capacitance per volume, the tantalum capacitors also have very low ESR or Equivalent Series Resistance reducing system losses. A downside of low ESR is that it may be too low to achieve stability in power supply regulators, which needs to be taken into account.

Why Use Tantalum Capacitors?

The tantalum capacitor also has excellent stability characteristics. The tantalum capacitor will maintain the expected capacitance better. With this stability you get more of the expected behavior of your system, which is especially important for filters; if the capacitance varies too much you may lose frequencies you desire. Beyond the electrical differences the construction of the tantalum capacitor also makes it highly resistant to vibration issues, improving overall system reliability.

The previous characteristics show how tantalum capacitors can be uniquely suited to help in modern electronics, but they are not without their quirks and there are a couple of major ones to take into account when you want to design these in. Tantalum capacitors are generally polarized devices, meaning that during layout and assembly you need to pay more attention to their orientation. This makes them a little more work than a regular ceramic capacitor, which is just a trait of electrolyte base capacitors. When putting tantalum capacitors into a system, you also need to watch out for their failure modes.

Tantalum Capacitor Failure Modes

Tantalum capacitors have a potentially dangerous failure mode. In case of voltage spikes, the tantalum anode could are available contact with the manganese dioxide cathode, and if the energy of the spike is sufficient it should begin a chemical reaction. This chemical process manufactures heat and is self-sustaining and will produce smoke and flame. To prevent this thermal runaway from happening, external failsafe electronic equipment like current limiters and thermal fuses should be utilized in conjunction with tantalum capacitors.

When to Use a Tantalum Capacitor?

So when do you want to use a tantalum capacitor? When you need maximum capacitance in a small space like decoupling next to a microchip, excellent stability over a range of temperatures or voltages, and you are aware of their unique characteristics so they can be designed in properly and not risk your system with a fiery failure.

Tantalum Capacitor advantages

·             High volumetric capacitance

·             High capacitance per unit weight

·            Reliable when used within electrical limits

·           Cost effective

·           Available in SMD format

·           Wide operating temperature range

Tantalum Capacitor disadvantages

·           Must be used within its electrical limits otherwise it can fail catastrophically.

·           High voltages and very high capacitance levels not normally available.

·           Does not like voltage above limits

·          Does not like reverse bias

·          Low ripple current rating