Paper Capacitors

Paper capacitors are a type of capacitor with a layered construction of aluminium sheets separated by waxed or oiled paper sheets. The paper between the aluminium acts as the dielectric (insulating) material. Some paper capacitors feature a cardboard cover while others are encapsulated in hard plastic.
What do capacitors do?
Capacitors are a type of passive component that stores an electrical charge. The more charge a capacitor can store, the larger its capacitance is. Capacitance is measured in denominations of farads – such as microfarads or picofarads.
What are the advantages and disadvantages of paper capacitors?
• Paper capacitors have a high working voltage and a high capacitance range. They are suited to high voltage and high current applications.
• The paper dielectric provides excellent stability and reliability of the component.
• Paper capacitors tend to have high leakage rates, making them unsuitable for applications such as AC coupling
• Paper capacitors typically have tolerances between ±10% and ±20%, making them unsuitable for precision timing circuits.

Polyester Film Capacitors

Polyester film capacitors are a type of capacitor (devices made of one or more pairs of conductors separated by an insulator, used to store an electrical charge), where the polyester film (PET) is used as the insulation material. Compared to other capacitors, polyester has great benefits. They’re a very popular and cheap capacitor making them brilliant use for all applications.


Polyester film capacitors are typically used as general purpose capacitors so can be used in a variety of products. They’re low cost, small and most have a high capacitance value. Typically they’re used for DC (Direct Current) applications or semi-critical circuits. Polyester film capacitors are also not polarized so they could be used for AC (Alternating Current) signal and power usage.

Most polyester film capacitors can be used in harsh environments where they need to withstand heat & moisture and some other characteristics. They make a great used for all applications.

Key characteristics

    • High dielectric (insulation) strength - The polyester dielectric used in these capacitors (Also referred to as PET) offers a high level of insulation

    • Operating temperatures - With the properties of the polyester dielectric our polyester capacitors can work up to temperatures of 125°C making them great use for harsh environments.

    • Tolerance - Many polyester film capacitors have a tolerance of 5% or 10%, but this is adequate for plenty of applications where insulation strength or temperature resistance are of greater concern.

  • Humidity resistance - Polyester film capacitors tend to have a brilliant resistance to moisture so makes them a great use in more harsh environments.

Aluminium Capacitors

Aluminium capacitors are a type of electrolytic capacitor. A capacitor is a two-terminal electrical component that can store energy, somewhat like a battery. Aluminium capacitors are polarised, meaning that the energy can only flow in a single direction. High purity grade Aluminium is used to create the anode foil and the cathode foil upon which electrolysis is applied to form an extremely thin insulating layer of aluminium oxide, which acts as the dielectric of the capacitor. Aluminium capacitors are found in many applications such as power supplies, computer motherboards and domestic appliances.

Dependent on the nature of the Electrolyte, capacitors may also be referred to as “wet” meaning they have a liquid electrolyte or solid. Solid Electrolytes may be hybridized with Aluminium but normally refers to Polymer or Tantalum based capacitors

Types of Aluminium Capacitors

Aluminium Electrolytic Capacitors

Electrolytic capacitors consist of an electrolyte which is a liquid or gel that consists of a large concentration of ions, and when voltage is applied across its terminals, it leads to charges being stored on the anode and cathode foils. The electric charge that can be stored by the capacitor is measured in Farads but usually in the range from nanofarads to millifarads. .Aluminium capacitors are used where high capacitance values to provide smoothing and filtering functions in the circuit. Commonly used in DC Power supplies due to their large capacitance and their compact size which helps to reduce the ripple voltage. Aluminium Electrolytic capacitors have reasonable Equivalent Series Resistance (ESR) but have the lowest leakage current from all capacitor types.

Polymer Electrolytic Capacitors

Polymer capacitors (also are known as polymer electrolytic capacitors or polymer e caps) have conductive polymer as their electrolyte material within a layered aluminium design. These capacitors combine unique properties from the polymer material in terms of high conductivity, extended temperature range and no risk of drying out – to make a capacitor that offers large capacitance and very low ESR (equivalent series resistance) with high ripple current capability and offer a longer operating life. Polymer capacitors offer a lot of package options between 2.2 to 470 microfarad

Hybrid Capacitors

Hybrid capacitors (polymer hybrid aluminium capacitors) are a mix of wet electrolyte and solid polymer. In this sense, they combine the best of both electrolytes. These capacitors offer high endurance, low ESR, and a high tolerance for ripple current. Hybrid capacitors also feature stable electric characteristics at high frequencies whilst maintaining reliability. The liquid electrolyte keeps the Leakage current very low and also allows self-repairing of the aluminium foils which prevent a drop in capacitance.

Ceramic Single Layer Capacitors

Ceramic single layer capacitors are ceramic capacitors which use ceramic as the insulating material. They are similar in construction to ceramic multilayer capacitors but have only one layer of insulating material instead of multiple layers.

What are ceramic single layer capacitors used for?

Ceramic single layer capacitors are suitable for high frequency decoupling in switching circuits due to their inductance and series resistance.

Ceramic multilayer capacitors are used when sufficient levels of capacitance need to be obtained within a single capacitor. Consequently, single layer capacitors are more limited when used as stand-alone capacitors. Multiple ceramic single layer capacitors can be used to increase the level of capacitance if this is required in a particular application.

Ceramic single layer capacitors are often used for temperature compensation, coupling and decoupling, resonant circuit, bypassing, AC power supply and filter applications.

Types of ceramic single layer capacitors

Ceramic single layer capacitors can vary in capacitance, voltage, packaging, tolerance and mounting type, for example, from 50 V up to 40 kV, capacitance of 1 pF to 470 nF, and with radial, axial, screw and surface mountings.

Polypropylene Film Capacitors

Polypropylene film capacitors are a commoncapacitor used in electrical equipment. They are made of two pieces of thin plastic film, charged with electrodes as the dielectric. They can replace electrolytic capacitors in applications where the voltage is above 500V.

Types of polypropylene film capacitors

There are two main formats of polypropylene film capacitors. They're distinguished by the type of dielectric (insulating) material used. Firstly, film foil has two metal foil electrodes separated with two plastic films. Whereas metallised film has two very thin layers of metallisation, with plastic film as the dielectric. To get the desired electrical characteristics you need, such as stability or ability to withstand high voltage, you can choose different film materials for the dielectric layer.

What are polypropylene film capacitors used for?

Because of their high tolerance and voltage resistance, polypropylene film capacitors are used in a wide range of electric applications. These include switching power supplies, high voltage circuit applications, lighting ballast systems and circuits with high peak current levels.

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