10 µF, 20 V, 2.1 Ohm ESR — the ESR is the thermal bottleneck
The TAJB106K020K: This is a 10 µF tantalum capacitor rated at 20 V with a 2.1 Ohm ESR. The ESR figure is the key thermal parameter: at a given ripple current, the power dissipated as heat is I² × ESR. For a 10 µF part in a B case, 2.1 Ohm is a mid-range value — it limits the AC ripple current the capacitor can handle before self-heating exceeds the 125 °C ceiling. In a DC-blocking or bypass role the ESR is less critical; in output filtering of a switching regulator it sets the ripple voltage and the capacitor's own temperature rise.
The capacitance tolerance of ±10% holds across the range, though the ESR rises at low temperature — expect roughly 2× the 25 °C value at -55 °C.
Active production — no end-of-life watch
KYOCERA AVX lists the TAJB106K020K as Active.
B case footprint — 1411 / 1210 land pattern
The capacitor uses the standard B case size: 3.50 mm x 2.80 mm footprint, 2.10 mm seated height. The package is listed as both 1411 (3528 Metric) and 1210 — these refer to the same body dimensions. The land pattern matches the TAJ-series recommended pad layout; reflow profile follows standard tin-lead or lead-free solder paste with a peak temperature of 260 °C.