Interpretation of seventeen common capacitors in detail

01 ceramic capacitor

This capacitor uses a ceramic material as a medium, which covers a layer of metal (silver) film on surface of ceramic, and then sintered at high temperature as an electrode. Ceramic capacitors are classified into Class 1 Dielectric Ceramic Capacitors (NPO, CCG), Class 2 Dielectric Capacitors (X7R, 2X1) and Class 3 Dielectric Capacitors (Y5V, 2F4).

Functions

Type 1 ceramic capacitors have advantages of small temperature coefficient, high stability, low loss and high withstand voltage. The maximum capacitance does not exceed 1,000 pF, CC1, CC2, CC18A, CC11, CCG and others series are commonly used.

Class 2 and 3 ceramic capacitors are characterized by high material permittivity, large capacitance (up to 0.47uF), small size and lower loss and insulation performance than class 1 capacitors.

Goal

Class 1 capacitors are mainly used in high frequency circuits. Types 2 and 3 are widely used in medium and low frequency circuits as DC blocking, isolation, bypass and filter capacitors. CT1, CT2, CT3 and other three series are commonly used.

Polyester Capacitor 02

The polyester capacitor is a non-polar positive temperature coefficient capacitor (that is, capacitance increases as temperature rises) made with polar polyester film as medium.

High temperature resistance, high pressure resistance, moisture resistance, low price. Typically used in medium and low frequency circuits. Commonly used models are CL11, CL21 and other series.

Polystyrene capacitor 03

These capacitors are available in both foil and metallized versions.

The foil type has high insulation resistance, small dielectric loss, stable capacitance and high accuracy, but it is large in size and has poor temperature resistance; The metallized type has better moisture resistance and stability than foil type, and can self-repair after breakdown, but insulation resistance is low and high-frequency performance is poor.

Usually used in medium and high frequency circuits. Commonly used models include CB10, CB11 (non-sealed foil type), CB14~16 (precision type), CB24, CB25 (non-pressure plating type), CB80 (high pressure type), CB40 (sealed plating type) and other series.

04 polypropylene capacitor

Non-polar NTC capacitor made with non-polar polypropylene film as medium. There are two types: non-sealed (usually used for sealing with colored resin paint) and sealed (sealed with a metal or plastic shell). Small loss, stable performance, good isolation and large capacitance.

It is commonly used in medium and low frequency electronic circuits or as a start capacitor for motors. Commonly used polypropylene foil capacitors: CBB10, CBB11, CBB60, CBB61, etc. Metallized polypropylene capacitors: CBB20, CBB21, CBB401 and other series.

05 monolithic capacitor

Monolithic capacitors are multilayer laminated ultra-small capacitors made from barium titanate ceramic materials and sintered.

The advantages are reliable performance, resistance to high temperatures and humidity, large capacitance (capacitance range 1pF ~ 1uF) and low leakage current. The disadvantage is low operating voltage (withstanding voltage below 100V).

Widely used in resonance, bypass, coupling, filtering, etc. Commonly used are CT4 (low frequency), CT42 (low frequency), CC4 (high frequency), CC42 (high frequency) and other series.

06 mica capacitor

Mica capacitors use mica as a medium, spray a layer of metal film (silver) on surface of mica as an electrode, and laminate them according to the required capacitance, then impregnate and press them into a bakelite shell (or ceramic, plastic case).

Good stability, small distributed inductance, high accuracy, low loss, large insulation resistance, good temperature and frequency performance, high operating voltage (50V~7kV), etc.

Commonly used for signal interconnection, bypass, tuning, etc. in high frequency circuits. Commonly used series are CY, CYZ, CYRX and others.

07 paper capacitor

Paper-dielectric capacitors are made by using thinner special capacitor paper as medium, using aluminum foil or lead foil as electrode, winding and forming, impregnating and packing. Large capacitance (100pF~100uF), wide operating voltage range, and maximum withstand voltage can reach 6.3kV.

Large volume, low capacitance accuracy, high loss and low stability. There are CZ11, CZ30, CZ31, CZ32, CZ40, CZ80 and other series.

Metalized paper capacitor 08

The metallized paper capacitor uses vacuum evaporation technology, whereby a layer of metal film is deposited on paper coated with ink film as an electrode.

Compared with ordinary paper capacitors, it has small volume, large capacitance and strong self-recovery ability after failure.

09 aluminum electrolytic capacitor

A polarized aluminum electrolytic capacitor is formed by winding an aluminum foil with an oxide film (positive electrode) and an electrolyte-impregnated backing paper together with a foil laminated cathode (negative electrode). The outer package is of tube type and vertical type. And on outside of aluminum case, there are blue or black plastic grommets.

The advantage is that capacitance range is large, typically 1 to 10,000uF, and rated operating voltage range is 6.3 to 450V. , -20%), poor resistance to high temperatures and long storage time, prone to failure.

Usually in DC power circuit or medium and low frequency circuits, it plays role of filtering, decoupling, signal coupling, time constant setting, DC blocking, etc. Note. Cannot be used on AC power circuits. When used as a filter capacitor in a DC power supply, polarity cannot be reversed.

10 tantalum electrolytic capacitor

Tantalum electrolytic capacitors are of two types:

Foil-type tantalum electrolytic capacitors. Inside, a winding core is used, negative electrode is a liquid electrolyte, and medium is tantalum oxide. Models CA30, CA31, CA35, CAk35 and other series.

Sintered type tantalum powder. The anode (positive electrode) is made of fine particle tantalum powder and then sintered. There are many types of packaging. Models include CA40, CA41, CA42, CA42H, CA49, CA70 (non-polar) and other series.

The advantages are low dielectric loss, good frequency response, high temperature resistance and low leakage current. The disadvantage is high production cost and low pressure resistance. It is widely used in various medium and low frequency and time constant circuits in communications, aerospace, military and household appliances.

11 mica trimmers

The fine-tuning mica capacitor consists of a fixed part and a moving part. The fixed part is a fixed metal part, and a layer of mica sheet is pasted on its surface as a medium. The moving part is an elastic copper or aluminum part, which can be adjusted by adjusting screw on moving part. The distance between moving part and fixed part is used to change the capacitance. Mica trimmer capacitors are divided into single and double trimmers.

The advantage is that capacity can be adjusted multiple times. Used in transistor radios, electronic instruments and electronic equipment.

12 ceramic trimmers

Porcelain trimmer capacitors use ceramic as a carrier. Both movable piece (porcelain piece) and fixed piece (porcelain piece) are coated with a semi-circular layer of silver, and capacitance can be changed by changing relative position between two silver pieces by rotating movable piece.

Small size, multiple adjustment, easy to use. Used in transistor radios, electronic instruments and electronic equipment.

13-film trimmer capacitor

Film trim capacitors use organic plastic film as carrier, that is, add an organic plastic film between moving part and fixed part (the moving part and fixed part are semi-circular metal parts), and adjust screw moving part to make moving part The capacity can be changed by turning slice. Film trimmer capacitors are usually divided into double trimmer and quad trimmer. Some sealed two-circuit or sealed four-terminal variable capacitors have their own thin-film trimmer capacitors, with trimmer capacitors mounted on top of case, which is more convenient to use and adjust.

Small size, light weight, multiple adjustment, easy to use. Used in transistor radios, electronic instruments and electronic equipment.

Air variable condenser 14

The electrodes consist of two sets of metal sheets. One group is fixed part and other is movable part, and air is used as a medium between movable part and fixed part. When movable part rotates so that it is fully screwed into fixed part, its capacity is largest, and vice versa, when movable part is completely unscrewed from fixed part, capacity is the smallest. Air variable capacitors are available in single and double configurations (see figure below).

The advantages are easy adjustment, stable operation and difficult to wear. The disadvantage is that it is bulky. Used in radio receivers, electronic instruments, RF signal generators and communication electronic equipment.

15-film variable capacitor

The film variable capacitor is a plastic film between moving part and fixed part as a medium, and body is a transparent or translucent plastic package, so it is also called sealed single connection or sealed double connection and sealed four-wire connection. variable capacitors are connected.

The advantages are small size and light weight. The downside is that noise is loud and easy to wear. The single connection is mostly used in simple radios or electronic instruments; double connection is used in transistor radios, electronic instruments and electronic equipment; four connections are commonly used in multi-band AF/FM radios.

16 polypropylene capacitor

CBB capacitors adopt a metallized polypropylene film series structure, which can withstand impact of high voltage and high current with little loss, excellent electrical performance, high reliability and self-healing.

The advantages are high dielectric constant, small size, large capacitance, good stability, high voltage and high current shock resistance, low loss, excellent electrical performance, high reliability and self-healing ability. The disadvantage is large temperature coefficient. Instead of most polyphenylene or mica capacitors, it is used in more demanding circuits.

17 safety capacitor

A protective capacitor usually consists of five parts: a dielectric, an electrode, a sheath, a body, and a pin. The medium is usually made of polypropylene film, electrode is made of metal vacuum evaporative layer, shell is usually made of flame retardant PBT plastic (UL94V-0), body is usually made of flame retardant epoxy resin (UL94V-0). -0) and pins consist of tinned steel wires clad with copper.

Once rejected, this will not result in electric shock and will not endanger personal safety. Capacitor x is a capacitor connected between two lines (L-N) of a power line. It is used to suppress differential interference. Typically, a metal film capacitor is used. Y capacitors are capacitors that are connected between two lines of power line and ground (L-E, N-E). They usually appear in pairs to suppress common mode noise. They are used at input terminal of power supply, that is, after failure of capacitor, it will not cause electric shock. Do not endanger personal safety.