What this 0.68 µF 20 V tantalum covers on the board
The TAJA684K020RNJ: This is a molded tantalum capacitor from the TAJ series, rated 0.68 µF at 20 V with ±10% tolerance, in a standard 1206 (3216 Metric) footprint.
The 1206 case measures 3.20 mm x 1.60 mm with a seated height of 1.80 mm max — standard two-terminal chip, no hidden thermal pad. Molded epoxy body handles hot-air rework fine; the orientation mark is on the top face. No moisture sensitivity level is listed, so a standard 24-hour bake at 125 °C before reflow is safe practice if the reel has been open.