The 20 V rating gives you 1.33× derating on a 15 V rail — standard practice for tantalum caps to keep the failure rate low. The 3 Ohm ESR sets the ripple current ceiling; at 1 µF the self-heating from ripple is modest, but if this cap sits on a switching regulator output, the ESR limits the ripple voltage to about 300 mV at 100 kHz with 100 mA ripple current.
Housed in a 1206 (3216 Metric) surface-mount case, 3.20mm x 1.60mm footprint, 1.80mm seated height.
