0.1 µF, 20 V, 25 Ohm ESR — decoupling or filter fit
The TAJS104M020RNJ: This is a Molded tantalum capacitor from the TAJ series, 0.1 µF ±20% at 20 V rated, with a 25 Ohm ESR. The 25 Ohm ESR is the thermal bottleneck: it limits the ripple current the part can handle before self-heating shifts the capacitance or dries the dielectric. For a 20 V rail decoupling a low-noise analog supply, the 0.1 µF value provides local charge storage at high frequency, but the ESR means the effective impedance at resonance is dominated by the resistive term, not the capacitive reactance.
-55 to 125°C — full military temp range
The 25 Ohm ESR at 25°C rises at cold and hot extremes, widening the impedance peak.
1206 case — footprint and reflow
The 1206 (3216 Metric) case, size code S, measures 3.20 mm x 1.60 mm with a seated height of 1.20 mm max. This is a standard footprint for tantalum chip capacitors — the land pattern matches the EIA 1206 solder pad geometry. The Molded construction gives a flat top for pick-and-place nozzle grip.