What is Ceramic Capacitor?
A ceramic capacitor is a value which is fixed, that is a capacitor which is where the material ceramic acts as a dielectric. It is constructed of two or more layers which are alternating ceramic and a layer which is metal and acting as the electrodes. The composition which is of the material that is ceramic defines the behaviour which is electrical and therefore applications. These whole things incorporate approximately one trillion that is 1012 pieces per year.
[Image will be Uploaded Soon]
Ceramic Capacitor Material
Titanium or Paraelectric dioxide that is rutile was used as the first dielectric in ceramic capacitors because it had a linear temperature that is dependent on capacitance for temperature compensation. This is a circuit of resonance and can replace mica capacitors. In the year 1926, these capacitors were produced in small quantities with increasing production quantities in the 1940s. The style which is of these early ceramics was disc-shaped with metallization on both sides which is contacted with wires which are tinned. This predates style of the transistor and was used extensively in vacuum-tube equipment that is the radio receivers from about 1930 through the 1950s.
Ceramic Disc Capacitor
The ceramic class 2 capacitors really have a dielectric with high permittivity and therefore we can say that it's a better volumetric efficiency than class 1 capacitors. But we can assume that the lower stability and accuracy of the dielectric ceramic is characterized by a charge which is nonlinear of capacitance over the temperature range. The value of capacitance also depends on the voltage which is applied. They are suitable for we can say that the bypass which is coupling and decoupling applications or we can say for the for frequency circuits discriminating where low losses and high stability of capacitance are less important. They typically exhibit microphones.
The capacitors that are of Class 2 are made of ferroelectric materials such as barium titanate BaTiO3 and the additive which is suitable such as silicon aluminium and the magnesium silicate and aluminium oxide. These ceramics which we have discussed have high to very high permittivity that is 200 to 14,000 which depends on the field strength. Hence we can say that the capacitance value of class 2 capacitors is nonlinear.
Ceramic Capacitor Detail
But these mixtures which we have discussed have a relatively low permittivity so that the value of capacitance which is of these capacitors are relatively small.
These materials which are dielectric have much higher permittivities. but here at the same time, their values of capacitance are less or more nonlinear over the range of temperature and losses at very high frequencies and are much higher. These are different characteristics which are of electrical or ceramic capacitors which are required to group them into "application classes".
Application of Ceramic Capacitor
The ceramic capacitors are divided into two application classes:
The Class 1 which capacitors offer high stability and low losses for resonant circuit applications.
The Class 2 capacitor offers high volumetric efficiency for buffer by-pass and applications which are coupling.
FAQs on Ceramic Capacitors
1. What is a ceramic capacitor and how is it constructed?
A ceramic capacitor is a type of fixed-value capacitor that uses a ceramic material as its dielectric. It is constructed from alternating layers of a conductive metal (acting as electrodes) and thin ceramic material. This layered structure is then sintered at high temperatures to form a compact, monolithic block. Its composition allows for a wide range of capacitance values and performance characteristics in a small physical size.
2. What are the main applications of ceramic capacitors in electronic circuits?
Ceramic capacitors are extremely common in electronics due to their versatility and performance at high frequencies. Their primary applications include:
- Decoupling and Bypassing: Placed near integrated circuits to filter out noise from the power supply.
- Filtering: Used in both high-pass and low-pass filters to block or pass signals of certain frequencies.
- Resonant Circuits: High-stability Class 1 ceramic capacitors are used in oscillators and timing circuits where precise frequency control is essential.
- Coupling: Used to block the DC component of a signal while allowing the AC component to pass between different stages of a circuit.
3. Do ceramic capacitors have polarity?
No, the vast majority of common ceramic capacitors, such as multilayer chip capacitors (MLCCs) and disc capacitors, are non-polarised. This means they can be connected in a circuit in either direction without risk of damage. This is a significant advantage over polarised capacitors like electrolytic types, which must be oriented correctly.
4. How can you identify the value of a ceramic capacitor?
The value of a ceramic capacitor is typically indicated by a three-digit code printed on its body. The first two digits represent the significant figures, and the third digit is the multiplier (the power of 10). The value is given in picofarads (pF). For example, a capacitor marked '104' means 10 × 104 pF, which equals 100,000 pF or 0.1 µF.
5. How does a ceramic capacitor fundamentally differ from an electrolytic capacitor?
The key differences between ceramic and electrolytic capacitors relate to their material, performance, and application.
- Dielectric Material: Ceramic capacitors use solid ceramic, while electrolytic capacitors use a thin oxide layer formed on a metal foil, with a liquid or gel electrolyte.
- Polarity: Ceramic capacitors are non-polarised, whereas electrolytic capacitors are polarised and must be installed correctly.
- Capacitance & Size: Electrolytic capacitors offer very high capacitance values in a small volume, making them ideal for power supply filtering. Ceramic capacitors typically have lower capacitance but perform much better at high frequencies.
- Application: Ceramic capacitors are used for high-frequency bypassing, coupling, and filtering. Electrolytic capacitors are used for low-frequency filtering and energy storage.
6. Why are ceramic capacitors classified into different 'classes' like Class 1 and Class 2?
Ceramic capacitors are classified based on their stability and dielectric constant (permittivity), which dictates their best use. Class 1 capacitors use paraelectric materials, offering very high temperature stability and low electrical losses, making them ideal for resonant circuits and filters. Class 2 capacitors use ferroelectric materials, which have a much higher dielectric constant, allowing for greater capacitance in the same volume (high volumetric efficiency). However, their capacitance changes significantly with temperature and voltage, making them suitable for bypass and decoupling applications where stability is less critical.
7. What physical properties make ceramic a good dielectric for capacitors?
Ceramic is an excellent choice for a dielectric material due to several key properties aligned with capacitor function. Primarily, it has a high dielectric constant (k), which allows for a high capacitance value in a small physical volume, as seen in the formula C = kε₀(A/d). Furthermore, it is a very good electrical insulator, preventing current from leaking between the electrode plates. It is also physically robust and can be manufactured into very thin, uniform layers, which is crucial for modern multilayer ceramic capacitors (MLCCs).
8. Can ceramic capacitors be used in both AC and DC circuits?
Yes, because they are non-polarised, ceramic capacitors can be safely used in both AC and DC circuits. In a DC circuit, they act as an open circuit once fully charged, effectively blocking DC current. In an AC circuit, they exhibit a certain reactance (opposition to current flow) that is inversely proportional to the frequency, allowing them to pass AC signals. This versatility is a major reason for their widespread use.
