What Are Aluminum Electrolytic Capacitors?

An aluminum electrolytic capacitor, commonly referred to as just an electrolytic capacitor, is a specialized component used in numerous network applications which operate with direct current (DC) power supplies. This includes implementation within systems used by industrial power supplies, various other electronic devices like DC converters to buff or smooth rectified current,  and standard power supplies. Although they have a tendency to exhibit low impedance values at lower frequencies, they find great use among power supplies, drives, inverters, certain converters, and more.

While the building blocks that construct capacitors vary based on use, aluminum electrolytic capacitors are fabricated with an anode, cathode, electrolyte, separator, encapsulation apparatus, and sealant, those of which can be found described below:

Andode: Anodes constructed for aluminum electrolytic capacitors are typically made from thin strips of foil between 20–100 micrometers (µm) in thickness with a purity rating of at least 99.99%. To give them their acquired characteristic, the surface of anodes are etched or “roughened” by an electromechanical process known as anodic oxidation which expands a foil’s total area to create a desired surface for electrons to travel.

Cathode: Often referred to as the cathode foil or “second foil,” cathodes are designed to make contact with the electrolytes present in the capacitor to facilitate current transfer.

Electrolyte: Electrolytes are what inspired the name for electrolytic capacitors, and they serve as the conductive liquid inside a capacitor. Generally, this solution consists of a particular ratio of solvents based on the product's intended application, meaning it can be adapted to suit conductivity requirements of various anodes with particular porous structures. Additionally, as  electrolytes aid a capacitor’s chemical stability, solvents chosen must be chemically compatible with aluminum to promote ion-conductivity of fluids. In turn, this bolsters the solvent’s flash point while having minimal negative environmental impact.

Separator: While containing both an anode and cathode, these individual parts must be separated within the electrolytic capacitor assembly. This is because close contact between both parts can cause a short circuit, even in low-voltage systems. To best prevent interference, a seperator or spacer made from a highly-absorbent, purified paper is routinely used and recommended.

Encapsulation Apparatus: It is standard for aluminum electrolytic capacitors to be encased in aluminum to mitigate unwanted galvanic reactions, a phenomenon where an electric current is spontaneously generated as a direct result of oxidation-reduction chemical reactions.

Sealant: The final step in assembling an electrolytic capacitor is the process of sealing the assembly in a material which protects the device from outside contaminants. Depending on the style of capacitor being constructed, different sealant materials and methods can be used, ranging from adhering plastic to applying a sealing washer made of phenolic resin and laminated rubber. However, other non-soluble compounds that are unaffected by chemical components residing within the capacitor can also be used.

When maintenance or item failure demands the replacement of parts, make sure action is immediately taken to safeguard electronics and personnel from potential accidents brought on by equipment malfunction. No matter what your particular capacitor part needs are, whether that be a tantalum capacitor, hermetic capacitor, or wet tantalum capacitor, among others, Aerospace 3sixty is here to assist you with any one of your individual product requirements. Moreover, to ensure the quality and authenticity of all our components, we operate with strict AS9120B, ISO 9001:2015, and FAA AC 00-56B accreditation, supported by unparalleled cost savings and rapid lead times on all orders. Promoting confident purchasing solutions through all avenues of the procurement process, experience premium items of the highest caliber when you choose to source from Aerospace 3sixty. For additional service inquiries, our representatives are available to assist you through phone or email 24/7x365! 

1. david johnson
2. Posted on October 20, 2022
aviation

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