Why the 9.6 Ohm ESR matters on this 1.5 µF tantalum
At 1.5 µF and 20 V, the TAJP155M020RNJ carries a 9.6 Ohm ESR — that is high enough to limit ripple current to roughly 200 mA RMS before self-heating becomes a concern. For a decoupling cap on a 20 V rail pulling fast transients, the ESR dominates the impedance at frequencies above a few hundred kHz; the cap will still filter bulk ripple but won't short high-frequency noise the way a lower-ESR MLCC would. The molded 0805 case (2.05 mm x 1.35 mm footprint, 1.50 mm seated height) is a standard size for high-density boards — rework with hot air is straightforward, though the tantalum body is more sensitive to thermal shock than a ceramic cap, so a preheat to 150°C before removal is worth the extra minute.
Active production — no obsolescence scramble
The TAJ series is a long-running molded tantalum line; the P case code (EIA 0805) is a common size that distributors carry across multiple capacitance/voltage combinations.
Temperature range and board fit
The ±20% tolerance is loose enough that the capacitance at -55°C (which typically drops 10-15% from the 25°C value) still stays within the 1.2 µF to 1.8 µF window.