47 µF, 4 V, 1206 — the BOM fit check
The TAJA476K004Y: This is a 47 µF molded tantalum capacitor rated at 4 VDC in the 1206 (3216 Metric) case size — the three numbers a buyer checks first against the BOM. The ±10% tolerance covers the standard decoupling and bulk-storage needs on a 3.3 V or 1.8 V rail where the 4 V rating provides 20% derating margin. The 2.6 Ohm ESR is typical for a size-A case at this capacitance and voltage. For a low-frequency bulk cap on a power input, the ESR is less critical than for a high-ripple switching regulator output.
Active production — no EOL clock ticking
The TAJ series is a long-running KYOCERA AVX line, so replacement risk is low for existing designs.
In an avionics black-box or a downhole tool that cycles from cold soak to internal heat, the capacitance shift stays within the ±10% tolerance band. The molded epoxy construction resists moisture ingress better than conformal-coated chips, though a vacuum bake before reflow is still recommended if the tape has been exposed to high humidity.
1206 footprint — board layout notes
The 1206 case measures 3.20 mm x 1.60 mm with a seated height of 1.80 mm max. The size-A code matches the standard KYOCERA AVX TAJ footprint — no special land pattern required.