All capacitors, including Tantalum Capacitors, have some degree of DC leakage. The leakage current value depends on the capacitor rating (capacitance-voltage), applied voltage, charging time and ambient temperature.
For accurate DC leakage measurements, the capacitors must be removed from the PC board and tested individually. The specified DC leakage is measured at 25 °C with the rated voltage applied through a 1000 Ω series resistance. The 1000 Ω resistor limits the possibility of damage and provides a convenient measurement point. The voltage drop across the resistor can be used to calculate DC leakage using Ohm’s law. For example, a voltage drop of 10 mV across a resistor corresponds to a DC leakage of 10 μA with the rated voltage applied. After the leakage current has stabilized (three to five minutes is the industry standard), the leakage current must not exceed the maximum value indicated in the data sheet.
Please note that Leakage current varies with temperature and voltage. Below example is the typical leakage current temperature factor of Solid Tantalum Surface Mount Chip Capacitors. 293D106X0016A2TE3 from Vishay.
