Active production — 0.22 µF, 35 V, 1206 molded tantalum
The TAJA224M035RNJ is an active-production KYOCERA AVX TAJ series molded tantalum capacitor, rated 0.22 µF at 35 V with ±20% tolerance, in a standard 1206 (3216 Metric) surface-mount package.
ESR and temperature profile — what 18 Ohm at 100 kHz means for decoupling
ESR is specified at 18 Ohm at 100 kHz — this is the series resistance that limits ripple current handling and sets the self-heating under AC load. For a 0.22 µF cap in a decoupling role, the ESR is high enough that the capacitor's own dissipation will dominate over the PCB trace resistance at switching frequencies above 100 kHz. The 2000-hour endurance at 125°C is the rated life under full rated voltage and temperature — derate the voltage or ambient temperature and the useful life extends well beyond that figure, which is common practice in designs where long-term reliability is a priority.