ภาษาอังกฤษเพื่อการทำงาน
aCharacteristics
General characteristics
Tantalum capacitors are made with capacitance values ranging from 1nF all the way to 72mF and they are much smaller in size than aluminum electrolytic capacitors of the same capacitance. The voltage rating for tantalum capacitors varies from 2V to more than 500V. They have an equivalent series resistance (ESR) ten times smaller than the ESR of aluminum electrolytic capacitors, which allows for larger currents to pass through the capacitor with less heat generated. Tantalum capacitors are very stable over time and their capacitance doesn’t change with age significantly, especially when compared to aluminum electrolytic capacitors. They are very reliable when handled properly and their shelf life is virtually unlimited.
Polarity
Tantalum electrolytic capacitors are exceptionally polarized devices. While aluminum electrolytic capacitors, which are polarized as well, might survive a briefly applied reverse voltage, tantalum capacitors are very sensitive to reverse polarization. If a reverse polarity voltage is applied, the dielectric oxide breaks down, sometimes forming a short circuit. This short circuit may later cause thermal runaway and destruction of the capacitor.
It should be noted that tantalum capacitors usually have their positive terminal marked, in contrast to aluminum electrolytic capacitors, which have their negative terminal marked on the casing.
Failure mode
Tantalum capacitors have a potentially dangerous failure mode. In case of voltage spikes, the tantalum anode may come in contact with the manganese dioxide cathode, and if the energy of the spike is sufficient it may start a chemical reaction. This chemical reaction produces heat and is self-sustaining and may produce smoke and flame. To prevent this thermal runaway from happening, external failsafe circuitry such as current limiters and thermal fuses should be used in conjunction with tantalum capacitors.
Read more http://www.capacitorguide.com/tantalum-capacitor/