Electrolyte residue with no droplets or visible flow is permitted. Aluminum electrolytic capacitors are polarized and must be connected in the correct polarity. They can withstand reverse voltages up to 1.5 V. Higher reverse voltage can cause failure by pressure build up and rupture of the capacitor’s safety vent structure.
Except for a few surface-mount technology (SMT) aluminum electrolytic capacitor types with solid electrolyte systems, an aluminum electrolytic capacitor consists of a wound capacitor element, impregnated with liquid electrolyte, connected to terminals and sealed in a can.
In non-polar aluminum electrolytic capacitors and motor-start aluminum electrolyte capacitors a second anode foil substitutes for the cathode foil to achieve a non-polar capacitor in a single case. These figures show typical constructions of the non-surface-mount aluminum electrolytic capacitors.
While tolerances of ±5% and ±10% are routine for ceramic capacitors, ±20% and –10% +50% are the norms for aluminum electrolytic. This makes aluminum electrolytics the choice for high-capacitance applications like rectification filters and power hold up where more capacitance is a bonus.
ial consideration must be given.(18) If more than 2 aluminum electrolytic capacitors are used in series, make sure the applied voltage will be lower than the rated voltage and that voltage will be applied to each capacitor equally using a balancing resistor
In SMT capacitors and miniature capacitors with rubber-bungs, extensions of the tabs are the capacitor terminals. But in large-can capacitors like snap-ins and screw-terminal styles, the tabs are riveted or welded on the underside of the capacitor tops to terminal inserts. Welding produces the lowest contact resistance and highest current handling.