Aluminium electrolytic capacitors are polarized capacitors that have a low level of tolerance and large capacitance values. They consist of aluminium foil which is an anode, electrodes which are an electrolyte, a separator and paper that encase the components. The paper turns into a barrier between the anode and cathode and allows ions to move in between, thus forming an electrical connection. The capacitance of the electrolytic capacitors is affected by the layer of oxide that is present on the anode. This layer is only one atom thick and can easily be oxidised if not handled properly.
Axial-lead aluminium electrolytic capacitors typically come in two types: those with straight leads and those with snap-in leads. These snap-in leads are designed for the easier assembling of printed circuit boards (PCBs). Axial-lead aluminium electrolytic capacitors offer higher capacitance than radial lead types and are suitable for higher frequency applications. As a result, these capacitors are popular in audio amplifiers and other similar electronics. They are also suitable for use in power conversion equipment, DC converters and power supplies.