This section provides overview, applications, and principles of monolithic ceramic capacitors. Also, please take a look at the list of 23 monolithic ceramic capacitor manufacturers and their company rankings.
A multilayer ceramic capacitor (Monolithic Ceramic Capacitor) is a chip component type capacitor with multiple layers of internal electrodes and dielectric layers. Further evolution of miniaturization and capacitance is projected in the capacitor industry.
Barium titanate and titanium oxide are mainly used as dielectric, and the inner electrode and dielectric are formed in multiple layers. Increasing the number of layers makes it possible to increase the capacitance, leading to the miniaturization of MLCCs.
Multilayer ceramic capacitors are available in chip and radial types. Compared to other capacitors, multilayer ceramic capacitors have low high-frequency impedance and ESR (equivalent series resistance) and good high-frequency characteristics.
Multilayer ceramic capacitors are available with a variety of features. The size, voltage withstand levels, temperature characteristics, and other factors must be taken into consideration when determining the type of capacitor to be used for a particular application. Multilayer ceramic capacitors can be classified into two main categories from the standpoint of characteristics: Class 1 and Class 2.
Class 1 capacitors are also called temperature-compensated capacitors, and can be compensated relatively easily due to their extremely low ESR and capacitance that does not vary much with temperature. The variation is linear.
However, the capacitance is usually small, ranging from 1pF to 1μF. ESRs are mainly used in applications where changes in capacitance are undesirable, such as oscillator circuits and time-constant circuits.
Class 2 is also called ferroelectric type, and its main material is barium titanate, which provides a large capacitance of about 100 μF even in the smaller size. However, there are many points to keep in mind when using it, such as a large ESR, vast temperature fluctuations in capacitance, and a decrease in actual capacitance when a DC bias is applied.
Therefore, when adopting Class 2 multilayer ceramic capacitors, circuit design must take their characteristics into consideration. The main applications of Class 2 multilayer ceramic capacitors are in circuits where slight changes in capacitance have little effect, such as for smoothing power sources and decoupling capacitors.
Multilayer ceramic capacitors have a wide range of applications because their performance can be selected according to the number of layers and their lineup is broad. Multilayer ceramic capacitors are used in cell phones, televisions, and industrial equipment for decoupling, coupling, and smoothing circuits, for smoothing in DC/AC converters, in computer power supplies, and for noise reduction.
For automotive applications, long-life and failure-resistant products are selected. For industrial equipment, high-capacitance and small capacitors are widely used, and in recent years they have been replacing other capacitors.
The capacitance C of a capacitor is proportional to the dielectric constant ε and the electrode area S, and inversely proportional to the distance d between electrodes. When capacitors are connected in parallel, the overall capacitance is equal to the sum of the capacitance of each capacitor.
Therefore, the key to increasing the capacitance of a capacitor is to use a dielectric with a high dielectric constant, increase the electrode area, and make the distance between electrode plates as small as possible. A multilayer ceramic capacitor has a structure consisting of many layers of very thin electrode plates, which can be thought of as many capacitors with a close distance between electrode plates connected in parallel.
In other words, the number of layers N is proportional to the capacitance C of the capacitor. Therefore, by increasing the capacitance with the number of layers N, a multilayer ceramic capacitor can be made both smaller and larger.
Although barium titanate has a very high dielectric constant and is used as a dielectric in most cases, its performance is expected to eventually plateau. Therefore, the development of materials that have a superior dielectric constant and are less prone to wear and tear is expected in the future.
Nickel is used for the electrodes and barium titanate is mainly used for the dielectric. Nickel paste, which serves as the internal electrode, is applied to the dielectric in the form of a sheet, and the sheet is then layered and formed under pressure.
It is then cut into small pieces and sintered at about 1000°C. When the external electrodes are attached, the capacitor becomes a multilayer ceramic capacitor. By ensuring that the internal electrodes are connected to the external electrodes alternately on the left and right, the layers are in the same state as if they were joined in parallel.
Since they are produced in sheet form, they have become more efficient, smaller, and thinner. The number of layers can be as many as 1,000. The dielectric materials are classified into two types: low dielectric constant type, which mainly uses titanium oxide, and high dielectric constant type, which uses barium titanate.
Class 1 is used for temperature compensation and low capacitance in signal circuits, etc. Class 2 has a high dielectric constant and a large temperature coefficient, and is used for power supply decoupling and smoothing circuits.
The capacitance of a multilayer ceramic capacitor varies with temperature. Therefore, when selecting a multilayer ceramic capacitor, it is necessary to consider not only the capacitance and voltage rating but also the temperature in the operating environment.
Multilayer ceramic capacitors are characterized by low equivalent series resistance (ESR) due to the use of metals such as nickel and copper in the electrodes. Also, due to their structure, multilayer ceramic capacitors are characterized by low parasitic inductance (ESL), which makes them suitable for use at high frequencies.
By taking advantage of these features of low ESR and ESL, it is possible to form resonant circuits with high Q-values and low-loss matching circuits, making MLCCs an indispensable component in the field of high-frequency circuit products, as well as in power supply decoupling and noise suppression applications.
By changing the number of layers of electrode plates, it is possible to control the capacitance from small to large. Therefore, the multilayer ceramic capacitor as a product is also characterized by a very wide range of capacitance in the available lineup.
*Including some distributors, etc.
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