Monolithic capacitor

Monolithic capacitors (multilayer capacitors):

Monolithic capacitors are another name for multilayer ceramic capacitors. The English name is monolithic ceramic capacitor or multi-layer ceramic capacitor, referred to as MLCC. There are two types of plug-in discrete and horizontal.

 

structure

The basic structure of a simple parallel plate capacitor is an insulated intermediate dielectric layer plus two conductive metal electrodes. The basic structure is as follows:
Therefore, the structure of the multilayer chip ceramic capacitor mainly includes three parts: ceramic dielectric, metal internal electrode, and metal external electrode. The multilayer chip ceramic capacitor is a multilayer

The structure is simply a parallel body of a plurality of simple parallel plate capacitors.

classification

one type
For temperature compensated NPO dielectrics
This capacitor has the most stable electrical performance. It basically does not change with temperature, voltage, and time. It is an ultra-stable, low-loss capacitor material type, suitable for high-frequency, ultra-high-frequency, and even high-reliability requirements. High-frequency circuits.
Second class
High dielectric constant X7R dielectric
Because X7R is a ferroelectric, it can produce capacitors with a larger capacity than NPO dielectrics. The performance of this capacitor is relatively stable. With the change of temperature, voltage and time, its unique performance changes are not significant. It belongs to the type of stable capacitor material. It is used in DC-blocking, coupling, bypass, filter circuits and high-reliability requirements Frequency circuit.
Three categories
For semiconductor type Y5V dielectric
This capacitor has a high dielectric constant and is often used to produce large-capacity capacitors with a large specific capacitance and a high nominal capacity. However, its capacity stability is worse than X7R, and its capacity and loss are more sensitive to test conditions such as temperature and voltage. It is mainly used in the oscillation, coupling, filtering, and bypass circuits of electronic complete machines.
Monolithic capacitors are larger than ordinary ceramic dielectric capacitors (10pF ~ 10μF), and have the advantages of large capacitance, small size, high reliability, stable capacitance, high temperature resistance, good insulation, and low cost, so they are widely used. Monolithic capacitors not only replace mica capacitors and paper dielectric capacitors, but also replace some tantalum capacitors, which are widely used in small and ultra-small electronic devices such as liquid crystal watches and miniature instruments.

Features and functions

Features
Good temperature characteristics and good frequency characteristics. In general, as the frequency increases, the capacitance shows a regular decrease. The monolithic capacitance decreases less and the capacity is more stable.
effect
1. Energy storage exchange
This is the most basic function of a monolithic capacitor. It mainly generates and discharges an electric energy through its charging and discharging process. This is mainly based on large-capacity type Ⅱ monolithic capacitors. In some cases, it can even replace small aluminum electrolytic capacitors and tantalum electrolytic capacitors.
2. Through straight traffic (bypass and coupling)

 


Because the monolithic capacitor is not a conductive body, it reflects the phenomenon of charging at both ends through the regular turning of the AC. Therefore, it can be connected in parallel with other components in the circuit to allow the AC to pass, and the DC is blocked. To play the role of bypass.
In the AC circuit, the monolithic capacitor is charged and discharged according to the polarity change of the input signal, so that the circuit connected to the two ends of the monolithic capacitor appears to be conducting, and plays a role of coupling.
Generally speaking, the monolithic capacitor connected to the amplifier or op amp input is a coupled monolithic capacitor; the monolithic capacitor connected to the amplifier or op amp emitter is a bypass monolithic capacitor.
Both are mainly type II monolithic capacitors, especially 0.1uF capacitors.
3.Frequency Discrimination Filter
In an AC circuit, for a multi-frequency mixed signal, we can separate it with a monolithic capacitor. In general, we can use a monolithic capacitor with reasonable capacitance to filter out most of the low-frequency signals. This is mainly based on high-frequency or ultra-high-frequency monolithic capacitors.
4. Surge voltage suppression
Because the monolithic capacitor is an energy storage element, in the circuit, it can remove those transient surge pulse signals, and it can also absorb the excess energy generated by the voltage fluctuation in the circuit. Filtering is mainly based on high-frequency products.

Application Status

Application:
Widely used in electronic precision instruments. Various small electronic devices are used for resonance, coupling, filtering and bypassing.
Capacity range:
10pF ~ 100μF
Withstand voltage:
Double the rated voltage.
Monolithic capacitors have the characteristics of small size, large specific capacity, long life, high reliability, suitable for surface mounting, etc., in addition to the common characteristics of the capacitors, which are "separated through". With the rapid development of the world's electronics industry, as a basic component of the electronics industry, monolithic capacitors are also developing at an alarming rate, increasing at a rate of 10 [%] ~ 15 [%] every year. The demand for monolithic capacitors in the world is more than 200 billion, 70 [%] comes from Japan, followed by Europe, America and Southeast Asia (including China). With the improvement of the reliability and integration of chip-capacity products, the range of its use is becoming wider and wider, and it is widely used in various military and civilian electronic machines and electronic equipment. Such as computers, telephones, program-controlled switches, precision test instruments, radar communications, etc.