What are aluminum electrolytic capacitors?

Aluminum electrolytic capacitors are (usually) polarized electrolytic capacitors whose anode electrode (+) is made of a pure aluminum foil with an etched surface. The aluminum forms a very thin insulating layer of aluminum oxide by anodization that acts as the dielectric of the capacitor.

Why do aluminum electrolytic capacitors have a safety vent?

To reduce the risk of violent rupturing of the case itself, aluminum electrolytic capacitors are usually equipped with pressure-relief vent structures that limit the maximum internal pressure. These safety vents are intended to rupture and release the gas pressure. After rupture the capacitor has limited life because its electrolyte evaporates.

What insulating layer is used in a capacitor?

The aluminum forms a very thin insulating layer of aluminum oxide by anodization that acts as the dielectric of the capacitor. A non-solid electrolyte covers the rough surface of the oxide layer, serving in principle as the second electrode (cathode) (-) of the capacitor.

What influenced the development of aluminum electrolytic capacitors?

The development of tantalum electrolytic capacitors in the early 1950s with manganese dioxide as solid electrolyte, which has a 10 times better conductivity than all other types of non-solid electrolytes, also influenced the development of aluminum electrolytic capacitors.

What are the different types of aluminum capacitors?

Aluminum capacitors with liquid electrolytes based on borax or organic solvents have a large range of types and ratings. Capacitors with water-based electrolytes are often found in digital devices for mass production. Types with solid manganese dioxide electrolyte have served in the past as a "tantalum replacement".

What does a radial capacitor look like?

Radial or single-ended electrolytic capacitors have a bar across the side of the capacitor to indicate the negative terminal. The negative terminal lead may be shorter than the positive terminal lead (similar to LEDs). In addition, the negative terminal may have a knurled surface stamped on the top of the connecting lug.