Basics

- How Electrolytic Capacitors are Made

The figure above is the internal structure diagram of a commonly used electrolytic capacitor. Most electrolytic capacitors (also known as e-caps) are polarized capacitors that are mainly formed of two thin layers of metal foil and paper spacer filled with electrolyte. A dielectric oxide layer acts as a dielectric medium - electrical insulation amid anode and cathode foil.

- Electrolytic Capacitors Symbol

The most common symbol for an electrolytic capacitor (polarized capacitor). The left diagram is by IEC standard (Europe) while the right one is by ANSI standard (the US).

- Why Choose Electrolytic Capacitors

An electrolytic capacitor can adapt to higher frequency circuits than a usual ceramic capacitor can do because of its high capacitance values. Besides, they do a better job than super-capacitors in handling ripple current. And they are built to low volume which saves lots of space on a board, saving direct cost.

Types & Applications

The electrolytic capacitor is a big family and has developed for nearly a century as a classic passive electronic component. Among the wide spectrum of e-cap, there are 3 kinds of them widely used in industry practice. They vary from each other in size, capacitance, and applications.

Aluminum, Tantalum and Niobium Electrolytic Capacitor

- Aluminum Electrolytic Capacitor

This kind of electrolytic capacitor has passed the longest period of design and manufacture, from the “Wet” type to the “Dry” type. They are named from the aluminum can which rolls up the anode and cathode and can be divided into the solid type and the non-solid type.

Nowadays, aluminum capacitors are largely used in camera flashes, automotive airbags, power-factor correction, etc. 

- Tantalum Electrolytic Capacitor

Tantalum capacitors are much more long-price than aluminum electrolytic capacitors. They produce low leakage with a high capacity and are often used with ceramic or film capacitors in power supply decoupling targets. Tantalum electrolytic capacitors feature a self-healing mechanism that functions to reduce MnO2 electrolytes into insulating Mn2O3. In addition, they behave superiorly stable in harsh environments (especially high-temperature ambient). 

- Niobium Electrolytic Capacitor

The niobium capacitor is relatively a young competitor in the market for the tantalum capacitor. They have a thicker dielectric layer and a lower breakdown voltage than tantalum capacitors. Besides the self-healing mechanism as tantalum capacitors inherent, niobium capacitors have one more feature: self-arresting mechanism. The mechanism operates to protect the chip from short circuits fault on account of local breakdown. What's more, they excel in resisting vibrations and shocks.

Niobium electrolytic capacitors favor their use in consumer, industrial, automotive, aircraft fields, and so on.