Why the molded case matters for your reflow and wash
The molded epoxy case gives consistent dimensions for pick-and-place and survives board washing solvents better than a dipped part, which can wick moisture along the leads.
ESR and ripple—what 6.5 Ohm buys you
ESR is specified at 6.5 Ohm at 100 kHz. For a 1 µF part at 35 V, that ESR is typical for a MnO2 tantalum in this case size. It sets the AC ripple current the capacitor can handle before internal heating becomes a derating factor—higher ESR means lower ripple capability, so check your ripple current against the datasheet power dissipation curve.
2000-hour life at 125 °C—derating is not optional
Rated life is 2000 hours at 125 °C with full rated voltage applied. Derate the applied voltage to improve field reliability beyond that window.