The TAJS684M020RNJ: This is a KYOCERA AVX TAJ series molded tantalum capacitor, 0.68 µF rated at 20 V with ±20% tolerance, in a standard 1206 (3216 Metric) surface-mount package. General-purpose rating means no special low-ESR or high-reliability screening; the 25 Ohm ESR is typical for a standard tantalum at this density and voltage, so budget the ripple current accordingly — at 20 V and 25 Ohm, self-heating is modest but real in a dense layout.
1206 case (3.20 mm x 1.60 mm footprint, 1.20 mm seated height) — the size code S matches the standard EIA 1206 land pattern; no via-in-pad or fine-pitch rework required. Molded body with no polarity marking ambiguity — the anode band is clearly printed on the top; a rework tech can eyeball orientation without a magnifier.