Types of Capacitors - Fixed, Array, Network, Variable & Supercapacitors | Questcomp.com

06 Nov, 2019 | Quest Components

Types of Capacitors

A capacitor is an electrical component that is capable of storing energy within an electromagnetic field. Capacitors are used for a variety of reasons and those reasons determine which type is best to use.

Each type of capacitor is uniquely designed to hold a certain amount of energy or adjust the amount of energy it can hold based on the immediate need. A capacitor’s makeup will determine its capacitance, meaning the amount of energy it can keep within the electromagnetic field.

Choosing the right capacitor can protect your equipment and save you money. Here’s what you need to know about the types of capacitors on the market.

 

Mounting: Through-hole vs. Surface Mount

One way that capacitors are characterized is by the way they are mounted.

Through-hole: In the through-hole mounting process the leads are placed in drilled holes on the printed circuit board (PCB) and are soldered to the board on the back of the PCB.

Surface mount: In the surface mount process the leads are soldered to the front surface of the PCB.

Fixed Capacitors

A fixed capacitor has a set capacitance that cannot be modified. Essentially, a fixed capacitor will only be able to hold a certain amount of energy or voltage within its electromagnetic field. There are a few different types of fixed capacitors that are characterized by the dielectric material (the non-conducting material separating the two charged plates).

Mica Capacitor. In this capacitor the metal foil plates are separated by mica, a silicate mineral. The capacitor is typically encased in molded plastic to prevent corrosion. Mica makes an effective dielectric because it can support a high voltage.

Ceramic Capacitor. A basic ceramic capacitor comes in two forms. One consists of a ceramic cylinder which serves as the base of the capacitor’s construction and the dielectric. The leads enter in one end of the cylinder and out the other end. Another type is disk-shaped, still using ceramic as the dielectric, where both leads exit from one side of the disk. Ceramic disk capacitors are mostly available in through-hole mounting style.

Monolithic Ceramic Capacitor. This capacitor uses multiple layers of ceramic as the dielectric, which reduces equivalent series inductance. The ceramic layers are pressed together forming a block. As with the ceramic disk capacitor, through-hole mounting is more readily available, such as this capacitor: SR205C104KAA.

Paper Capacitor. Wax paper is the dielectric used between the two plates in this capacitor encased in a wax coating. Paper capacitors have the lowest capacitance of any of the fixed capacitors.

Electrolytic Capacitor. When a large amount of capacitance is needed, an electrolytic capacitor is ideal. An electrolytic capacitor contains an electrolyte as the dielectric. The electrolyte can be wet or dry, although wet electrolytic capacitors are used less because of the high risk of spillage. Electrolytic capacitors are available in both through-hole and surface mount options. This is an example of a through-hole mounted aluminum electrolytic capacitor: UVX1C471MPA.

Tantalum Capacitor. This is a subtype of electrolytic capacitor, where tantalum metal acts as the dielectric. The advantage of using tantalum is that a very thin layer can be used, reducing the capacitor’s footprint on the PCB. Tantalum capacitors are available in both through-hole and surface mount options. This through-hole capacitor, T350E106K016AS, is a solid tantalum capacitor.

Oil Capacitor. Ideal for high-powered electronics, an oil capacitor is basically a paper capacitor where the paper has been soaked in oil. The oil-soaked paper increases the capacitance of the paper dielectric, making it possible for it to withstand a higher voltage. A major advantage to the oil capacitor is that it is a self-correcting system, as the oil tends to seal any holes that may be created by arcing plates.

Multi-Layer Chip Capacitor. Best for small capacitance use, multi-layer chip capacitors consist of alternating layers of electrodes and dielectrics. These perform better in high-frequency situations and have greater temperature stability than other types, such as this surface mount multilayer ceramic capacitor: GRM155R71C104KA88D.

Film Capacitor. A film capacitor uses a very thin plastic layer as the dielectric. These capacitors can be made with very precise capacitance values that hold their capacitance over time. There are different types of film used, such as polyester, metallized, polypropylene, PTFE, and polystyrene. The purpose and cost may be the biggest determinants in which type to choose

Glass Capacitor. Using glass as the dielectric, this capacitor is known for its excellent performance. Capacitance is usually low, and the cost of these capacitors tend to be high because of their reliability and precision.

Variable Capacitors

A variable capacitor is capable of being adjusted so that the capacitance can vary.

Rotor and Stator. Some variable capacitors operate with a rotor and stator system using air as the dielectric. As the rotor turns and changes position the amount of air is increased or decreased, the capacitance changes.

Trimmer capacitor. This capacitor consists of two plates separated by mica, the dielectric. It is easily adjusted using a screw mechanism to change the distance between the plates, which changes the capacitance.

Arrays and Network Capacitors

A way to reduce cost and simplify design is with array or network capacitors. An array consists of a set of multiple capacitors in unified packaging. In an array the capacitors are not connected.

Special Capacitors / Industrial Capacitors

Supercapacitors. These have an extremely high capacitance when compared to other capacitors. Their capacitance lies somewhere between an electrolytic capacitor and a rechargeable battery. They charge more quickly than batteries and can operate under a wider range of temperatures. Supercapacitors can be used for a wide range of industrial applications from public transportation to computer electronics. This electrolytic double layer capacitor is a super capacitor with a through-hole mount: DB-5R5D105.

Get the Right Capacitor for your Needs at Quest Components

Whatever type of capacitor you’re looking for from small to large capacitance, you can find it in the wide inventory capacitor electrical components at Quest Components. Order online or call (626) 333-5858 today to speak with a representative who can help you choose the right capacitor for your needs.

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