Types of Capacitor

Capacitors are most commonly used component in most of electronic circuits. Whatever Types of Capacitor and its capacitance value, a correct selection of capacitor resolves many issues in a circuit application.

Please visit below links of my previous blogs to get more details about Capacitor;

"Capacitor and Working of Capacitor"

"Uses of Capacitor"

Different Types of Capacitors and Their Applications

There are many Types of Capacitor and according to the advantages, disadvantages and applications we can select capacitor type and capacitance value. In this article, we will discuss about different Types of Capacitor.

Ceramic capacitors

Ceramic capacitors are non-polarized fixed capacitors. They are made by two layers or some times more than two layers of ceramic and metal. Here finely powdered granules of ceramic material are used as dielectric and both the side two metal electrodes are attached.

Ceramic Capacitors

Type of Capacitor – Class 1 Ceramic

Used Dielectric Material – Para-electric ceramic combination of Titanium dioxide amended by additives.
Advantages – These types of capacitors gives predictable linear and low capacitance value change with working temperature. These capacitor types have superb high frequency characteristics with low losses.
Drawbacks – Used ceramic have low permittivity, low volumetric efficiency these types of capacitors have, compare to Class2 capacitors these have larger dimensions.
Applications – These capacitors can be use for temperature compensation in resonant circuit. These capacitors can support voltages up to 15,000V.

Type of Capacitor – Class 2 Ceramic

Used Dielectric Material – Ferroelectric ceramic mixture of Barium Titanate and appropriate additives
Advantages – These types of capacitors have high permittivity and high volumetric efficiency. These capacitors are smaller in dimensions as compare to Class 1 ceramic capacitors. These are available in voltages up to 50,000V.
Drawbacks – As compare to Class 1 ceramic these capacitors have lower stability and higher losses. Capacitance of these capacitor changes with change in the applied voltage, frequency and aging effects. These are slightly microphonic. Microphonics or microphony defines the process or phenomenon where some components in electronic devices change mechanical vibrations into an undesired electrical signal i.e. noise.
Applications – Applications of these capacitors are mostly for buffer, for by-pass and also used as coupling capacitor.

Film capacitors

Film capacitors or plastic film capacitors have no polarity. This capacitor type uses thin layer of an insulating plastic film as the dielectric. This thin dielectric film wound in cylindrical shape and at both the side metallic electrodes is attached.

Film Capacitors

Type of Capacitor – Film/foil based film capacitors

Used Dielectric Material – Polypropylene (PP), Polyester (PET), Polytetrafluoroethylene (PTFE)
Advantages – These capacitors can sustain highest surge ratings/pulse voltages. As compare to metallized types here peak currents are higher.
Drawbacks – These capacitors don’t have self-healing properties. These capacitors have larger dimensions than metallized film capacitors.
Applications – These capacitors are widely used in power electronics applications like DC Link, DC output filtering and as IGBT snubbers.

Type of Capacitor – Metallized film capacitors

Used Dielectric Material – Polypropylene (PP), Polyester (PET), Polyethylene naphthalate (PEN), Polyphenylene Sulfide (PPS), Polytetrafluoroethylene (PTFE)
Advantages – These capacitors are considerably smaller in size as compare to film/foil types and these capacitors have self-healing characteristics.
Drawbacks – Thin metallized electrodes limits the full current carrying ability of these capacitors.
Applications – These capacitors are widely used in power electronics applications like DC Link, DC output filtering and as IGBT snubbers.

Type of Capacitor – Polypropylene (PP) film capacitors

Used Dielectric Material – Polypropylene
Advantages – This dielectric is most common film for capacitor. Here in these capacitors low capacitance change with operating temperature. Class – 1 application like frequency-determining circuits and precision analog applications these capacitors are suitable. Capacitance range in these capacitors is in narrow range and have low dissipation factor. Advantage of low moisture absorption makes it suitable for the designs where coating is not needed. Also these capacitors have high insulation resistance.
Drawbacks – These capacitors have maximum operating temperature of 105 °C and also have relatively low permittivity of 2.2. As compare to other capacitors these capacitors are larger than other film capacitors. For pulsed power applications these capacitors mostly damaged from transient over-voltages or voltage reversals as compare to MKV-capacitors.
Applications – Mostly these capacitors are used in high power applications such as snubber or IGBT and in AC power applications for power factor correction in motors. We can see these capacitors in high frequency and high power applications like induction heating. Also they are used for safety/EMI suppression.

Type of Capacitor – Polyethylene naphthalate (PEN) film capacitors

Used Dielectric Material – Polyethylene naphthalate (Kaladex®)
Advantages – As compare to PET capacitors these capacitors are more stable at high temperatures. More appropriate for high temperature applications.
Drawbacks – As compare to PET capacitors they have lower relative permittivity and lower dielectric strength, which results in larger dimensions for a capacitance value and rated voltage.
Applications – As temperature requirements are not important they are mainly used for non-critical filtering, coupling and decoupling.

Type of Capacitor – Polyester (PET) film (Mylar) capacitors

Used Dielectric Material – Polyester (Hostaphan®, Mylar®), Polyethylene terephthalate
Advantages – These capacitors are in smaller in size as compare to polypropylene film capacitors. Advantage of low moisture absorption makes them to appear in most DC applications. They can work up to 60,000Vdc.
Drawbacks – We can use them only for frequency application. Restricted use in power electronics because of higher losses, which appears because of increase in temperature and frequency.
Applications – They are mainly used for general purpose applications or semi-critical circuits with operating temperatures up to 125°C.

Type of Capacitor – Polyphenylene Sulfide (PPS) film capacitors

Used Dielectric Material – Polyphenylene (Torelina®)
Advantages – These capacitors have quality of small temperature dependency over the whole temperature range and also they have narrow frequency dependency in a wide frequency range. The dissipation factor of these capacitors is relatively small and steady. Working temperature of this capacitor is up to 270 °C.
Drawbacks – The dissipation factor increases when the temperature crosses 100°C, which further increases capacitor temperature, but it will not cause any critical problem and can work without degradation. Cost is usually higher than Polypropylene (PP) film capacitors.
Applications – Mostly suitable for SMD package application.

Type of Capacitor – Polytetrafluoroethylene (PTFE) capacitors (Teflon film capacitors)

Used Dielectric Material – Polytetrafluoroethylene (Teflon®)
Advantages – These capacitors have less loss and have working temperature up to 250°C. These capacitors have very high insulation resistance and good constancy.
Drawbacks – Because of low dielectric constant they have large size. As compare to other film capacitors these capacitors have high cost.
Applications – Used in critical applications.

Type of Capacitor – Polystyrene (PS) film capacitors

Used Dielectric Material – Polystyrene (Styroflex)
Advantages – This capacitor have good thermal stability and high insulation along with low distortion.
Drawbacks – As these capacitors are replaced by Polyester (PET) film (Mylar) capacitors so, limited manufacturers produce this capacitor.
Applications – Same like Polyester (PET) film (Mylar) capacitors

Type of Capacitor – Polycarbonate (PC) film capacitors

Used Dielectric Material – Polycarbonate
Advantages – Advantages are same like Polypropylene (PP) film capacitors.
Drawbacks – As these capacitors are replaced by Polypropylene (PP) film capacitors so, limited manufacturers produce this capacitor.
Applications – Same like Polypropylene (PP) film capacitors

Type of Capacitor – Polysulfone film capacitors

Used Dielectric Material – Polysulfone
Advantages – Endure full voltage at relatively high temperatures.
Drawbacks – Only development and hard to find.
Applications – Same like Polycarbonate (PC) film capacitors and Polypropylene (PP) film capacitors

Type of Capacitor – Polyamide film capacitors

Used Dielectric Material – Polyamide
Advantages – Operating temperatures of up to 200°C. High insulation resistance. Good stability. Low dissipation factor.
Drawbacks – Only development and hard to find.
Applications – These capacitors are used in critical applications.

Type of Capacitor – Polyimide film (Kapton) capacitors

Used Dielectric Material – Polyimide (Kapton)
Advantages – Highest dielectric strength of any known plastic film dielectric.
Drawbacks – Only development and hard to find.
Applications – These capacitors are used in critical applications.

Power film capacitors

The construction of this capacitor is same like normal film capacitors, but this type of capacitor supports high voltage application in electrical installations. As, it deals with high voltage and may cause safety risk to people and applications, a certification or product approval from local regulating authority is must needed.

Power Film Capacitors

Type of Capacitor – Metallized paper power capacitors

Used Dielectric Material – Paper impregnated with insulating oil or epoxy resin
Advantages – These capacitors supports self-healing. Mostly wax or oil is used but for high voltage applications oil-Kraft paper is used.
Drawbacks – Size of this capacitor is large and heavy as compare to PP dielectric. These capacitors are very hygroscopic i.e. it absorbs moisture from the air which causes dielectric losses and decreases insulation resistance.
Applications – High voltage applications and supports all Polypropylene (PP) film capacitor applications.

Type of Capacitor – Paper film/foil power capacitors

Used Dielectric Material – Kraft paper impregnated with oil
Advantages – Low cost because of paper covered with metal foils as electrodes.
Drawbacks – Size of this capacitor is large and heavy as compare to PP dielectric. Not support self-healing. High stored energy may cause catastrophic failure.
Applications – These capacitors are used in the applications related to high discharge voltage.

Type of Capacitor – Single- or double-sided metallized PP power capacitors

Used Dielectric Material – PP as dielectric, impregnated with insulating oil, epoxy resin or insulating gas.
Advantages – This capacitor supports high capacitance value and also heals it-self.
Drawbacks – This type of capacitor are not reliable for high voltage operation and very high inrush current loads. Supported heat resistance is 105°C.
Applications – This type of capacitors are used in general purpose applications, AC applications, motors, filtering, snubbing, series resonant DC circuits, DC discharge, AC commutation, power factor correction, AC damping and DC links.

Type of Capacitor – PP dielectric, field-free paper power capacitors (MKV power capacitors)

Used Dielectric Material – Double-sided (field-free) metallized paper as electrode carrier. PP as dielectic, impregnated with insulating oil, epoxy resin or insulating gas.
Advantages – These capacitors supports self-healing and low losses. These have high insulation resistance and can sustain inrush current.
Drawbacks – Size of this capacitor is larger than PP power capacitors.
Applications – These types of capacitors are used in heavy duty applications like; commutating with high reactive power, high frequencies and high peak current load.

Type of Capacitor – PP film/foil power capacitors

Used Dielectric Material – Impregnated PP or insulating gas, epoxy resin or insulating gas, insulating oil
Advantages – It can sustain highest inrush current.
Drawbacks – Size of this capacitor is more as compare to the PP metallized versions and also didn’t heal it-self.
Applications – This type of capacitors are used in general purpose applications, AC applications, motors, filtering, snubbing, series resonant DC circuits, DC discharge, AC commutation, power factor correction, AC damping and DC links.

Electrolytic capacitors

Electrolytic capacitors are polarised capacitors and for proper identification negative (-) sign is marked on the capacitor body. These types of capacitor are generally used when very high capacitance values are needed.

Electrolytic Capacitors

This capacitor type has a metal anode concealed with an oxidized layer which is used as dielectric material. The second electrode is in the form of non-solid or semi-liquid or solid electrolyte. This is usually the cathode.

The dielectric is a very thin layer of oxide sometimes less than ten microns. Because of this there is very small distance between plates and hence we can get large capacitance value with small size of capacitor.

Type of Capacitor – Electrolytic capacitors with non-solid (wet, liquid) electrolyte

In this there are two types of dielectric materials are used;

1st Type;

Used Dielectric Material – Aluminium oxide Al2O3
Advantages – These capacitors are available with high capacitance which ranges up to 2,700,000µF. Voltage level is available from 6.3V to 550 V. Cost varies from low to high as according to capacitance and voltage value.
Drawbacks – These capacitors have polarized connections and have leakage. These capacitors have high ESR and ESL values which limits its use in high ripple current and high frequency uses. Because of drying out characteristic we have to perform lifetime calculation. It burst when it is overheated, overloaded or wrongly connected (polarity connection).
Applications – These capacitors are used where the low losses and high capacitance constancy are not important criteria, particularly for lower frequencies applications like coupling, by-pass, smoothing and buffer applications in switched mode power supplies and DC-links.

2nd Type;

Used Dielectric Material – Tantalum pentoxide Ta2O5
Advantages – Wet tantalum electrolytic capacitors (wet slug) have lowest leakage among all electrolytes. It supports voltage level up to 630V (tantalum film) or 125V (tantalum sinter body). These are sealed hermetically sealed.
Drawbacks – These capacitors have polarized connections and are costly. Burst when voltage, ripple current or slew rates are surpassed or under reverse voltage.
Applications – Military and space applications.

Type of Capacitor – Electrolytic capacitors with solid Manganese dioxide electrolyte

Used Dielectric Material – Aluminium oxide Al2O3, Tantalum pentoxide Ta2O5, Niobium pentoxide Nb2O5.
Advantages – These capacitors give constant electrical parameters and good temperature performance for long-term.
Drawbacks – These capacitors have polarized connections and supports voltage level only up to 125V. These capacitors support limited transient, reverse or surge voltage.
Applications – These capacitors are used for smoothing and buffering application in power supplies.

Type of Capacitor – Electrolytic capacitors with solid Polymer electrolyte (Polymer capacitors)

Used Dielectric Material – Aluminium oxide Al2O3, Tantalum pentoxide Ta2O5, Niobium pentoxide Nb2O5.
Advantages – These capacitors have less ESR as compared to manganese or non-solid (wet) electrolytes. They have higher ripple current ratings which increases operational life. They support stable electrical parameters along with self-healing.
Drawbacks – These capacitors have polarized connections and have highest leakage current among electrolytes. They are costly and limit voltage level up to 100V. If voltage, current, or slew rates are exceeded or under reverse voltage these capacitors may explode.
Applications – These capacitors are used for smoothing and buffering application in power supplies.

Supercapacitors

The supercapacitor, also sometimes called as ultracapacitor or electric double-layer capacitor (ELDC). Also, we can hear name as pseudocapacitors and hybrid capacitors. This type of capacitor is from a family of electrochemical capacitors and has very high capacitance. They don't have a normal used solid dielectric.

Supercapacitors

Type of Capacitor - Supercapacitors Pseudo-capacitors

Used Dielectric Material – Helmholtz double-layer plus faradaic pseudo-capacitance
Advantages – These are more like batteries as these have energy density typically from tens to hundreds of times more than nominal electrolytic capacitors. The capacitance value we can get in thousands of farads along with low ESR. They rapidly absorb and deliver much more currents as compare to batteries and support hundreds of thousands of charge and discharge cycles.
Drawbacks – These capacitors have polarized connection and have low operating voltage per cell, but stacked cells provide higher operating voltage. They come with high price.
Applications – These capacitors are used for RAM memory backup, short-term power during battery replacement and hybrid vehicles.

Type of Capacitor – Hybrid capacitors Lithium ion capacitors (LIC)

Used Dielectric Material – Helmholtz double-layer plus faradaic pseudo-capacitance. Lithium ions are use to dope anode.
Advantages – These capacitors support higher operating voltage and higher energy density. These are smaller than lithium ion batteries. Also, there are no thermal runaway reactions.
Drawbacks – These capacitors have polarized connection and have low operating voltage per cell, but stacked cells provide higher operating voltage. Also have high price.
Applications – These capacitors are used for RAM memory backup, short-term power during battery replacement and hybrid vehicles.

Class X and Class Y capacitors

Whenever Lightning strikes happen it causes high voltage surges in mains power. Class X and Class Y safety capacitors safeguard humans and electronic devices from high voltage surges by moving the high surge voltage to the ground.

Class X and Class Y Capacitors

Class X and Class Y should be connect in the circuit in a pre-define manner as mentioned in the safety regulations.

Type of Capacitor – Class X and Class Y

Used Dielectric Material – Any dielectric could be used. Normally ceramic or plastic film is used mostly.
Advantages – It provides galvanic isolation even when the capacitor fails.
Drawbacks – Very high cost.
Applications – RFI/EMI suppression.

Miscellaneous capacitors

These are some newly developed or special application specific designed capacitors.

Type of Capacitor – Air gap capacitors

Used Dielectric Material - Air
Advantages – These capacitors have low dielectric losses.
Drawbacks – These capacitors are large in size and have low capacitance.
Applications – They are used for resonating circuits for high power high frequency welding.

Type of Capacitor – Vacuum capacitors

Used Dielectric Material – Vacuum
Advantages – These capacitors support very low losses. If arc-over current is limited then they can self-heal.
Drawbacks – Very high cost and are fragile. Comparatively they have low capacitance.
Applications – These capacitors we can see in applications related to high voltage, high power RF applications; like transmitters and induction heating.

Type of Capacitor – Metallized mica (Silver mica) capacitors

Used Dielectric Material – Mica
Advantages – These capacitors have very high stability along with low losses. They have long life. They can be replaced easily by Class 1 ceramic capacitors.
Drawbacks – Higher cost than class 1 ceramic capacitor.
Applications – These capacitors are used for HF and low VHF RF circuits and as standard capacitance in measuring bridge circuits.

Type of Capacitor – SF6 - gas filled capacitors

Used Dielectric Material – SF6 gas
Advantages – These are high précised capacitors and have very low losses. These capacitors can support voltage level up to 1600kV.
Drawbacks – They have very high price.
Applications – They can be used as standard capacitance in measuring bridge circuits.

Type of Capacitor – Glass capacitors

Used Dielectric Material – Glass
Advantages – These capacitors have better stability and frequency than silver mica capacitor. They are ultra-reliable, ultra-stable and resistant to nuclear radiation. There working temperature ranges from: −75 °C to +200 °C and some time they support up to +250 °C.
Drawbacks – Cost is high than class 1 ceramic.
Applications – These capacitors we can found in the circuits like; tuners, oscillators, crystal oscillators and filters.

Type of Capacitor – Integrated capacitors

Used Dielectric Material – oxide-nitride-oxide (ONO)
Advantages – These capacitors are thin (up to 100µm). Also have smaller footprint as compare to most MLCC. Low ESL, high reliability and very high stability up to 200°C are other advantages.
Drawbacks – Personalized production
Applications – These capacitors we can found in the circuits like; tuners, oscillators, crystal oscillators and filters.

Variable capacitors

The capacitance of Variable capacitors is changed by mechanical variation. This mechanical construction changes the distance between the plates and hence the capacitance change. Dielectric medium is used here is mostly air.

Tuning capacitor and Trimmer capacitor are the two variations of variable capacitors.

Variable Capacitors

Type of Capacitor – Air gap tuning capacitors

Used Dielectric Material – Air
Advantages – These capacitors have circular or numerous logarithmic cuts of the rotor electrode for different capacitance bends. These capacitors have split rotor or stator cut for symmetric tuning. Also have ball bearing axis for reducing noise.
Drawbacks – They have large dimensions and have high cost.
Applications – Used mostly for high specialized applications.

Type of Capacitor – Vacuum tuning capacitors

Used Dielectric Material – Vacuum
Advantages – Extremely low losses. If arc-over current is limited then they can self-heal.
Drawbacks – Very high cost and are fragile. They have large dimensions.
Applications – These capacitors we can see in applications related to high voltage, high power RF applications; like transmitters and induction heating.

Type of Capacitor – Air gap trimmer capacitors

Used Dielectric Material – Air
Advantages – Semi-conductive variable capacitance diodes replaced these capacitors.
Drawbacks – Cost is high
Applications – These capacitors we can see in very high voltage high power RF applications.

Type of Capacitor – SF6 gas filled tuning capacitor

Used Dielectric Material – SF6
Advantages – Very low losses.
Drawbacks – Very high price, delicate, big dimensions
Applications – These capacitors we can see in very high voltage high power RF applications.

Type of Capacitor – Ceramic trimmer capacitors

Used Dielectric Material – Class 1 ceramic
Advantages and Applications – Linear and stable frequency behaviour over wide temperature range.
Drawbacks – High cost
Applications – They are used when there is a need of matching capacitance value to a predefined value or as per circuit requirement. They are usually used in various RF circuits, VHF through microwave. Non-magnetic types of capacitors are used in medical instruments such as MRI and NMR scanners. Also, these capacitors we can found in the circuits like; tuners, oscillators, crystal oscillators and filters. We can see these capacitors in communication apparatus like; mobile radios and aerospace transmitters-receivers, CATV amplifiers and signal splitters.

Conclusion

Now we know all types of capacitor, and now we are familiar with their advantages, disadvantages and their applications. Capacitor is a critical component in a circuit. Correct selection of capacitor and its capacitance value decides life of your circuit.