MLCC is the abbreviation of Multi-layer ceramic capacitor. Although its size is small, its capacity is large. It is often used in various circuits such as decoupling, smoothing of power supply voltage, and filtering. It is a component that cannot be obtained to improve the performance of home appliances such as mobile phones and TVs.
It is the most widely used type of chip components. It is a multi-layer alternate stack of internal electrode materials and ceramic bodies in parallel, and co-fired into a whole, also known as chip monolithic capacitors, with small size, With the characteristics of high specific volume and high precision, it can be mounted on printed circuit boards and hybrid integrated circuit substrates, effectively reducing the volume and weight of electronic information terminal products and improving product reliability.
In line with the development direction of miniaturization, light weight, high performance and multi-function of the IT industry, MLCC not only has simple packaging and good sealing performance, but also can effectively isolate opposite electrodes.
MLCC can play the role of storing charge, blocking DC, filtering, combining, distinguishing different frequencies and tuning circuits in electronic circuits. It can partially replace organic film capacitors and electrolytic capacitors in high-frequency switching power supplies, computer network power supplies and mobile communication equipment, and greatly improve the filtering performance and anti-interference performance of high-frequency switching power supplies.
Features of MLCCs
1. Bypass
MLCC has many functions. The primary function is bypass, which is an energy storage device that provides energy for local devices. It can make the output of the voltage stabilizer uniform and reduce the load demand. Like a small rechargeable battery, the bypass capacitor can be charged and discharged to the device. To minimize impedance, bypass capacitors should be placed as close as possible to the power supply and ground pins of the load device. This is a good protection against ground potential rise and noise caused by excessive input values. Ground potential is the voltage drop across the ground connection through a high current glitch.
2. Decoupling
The second is decoupling. The decoupling capacitor acts as a "battery" to meet the change of the current of the drive circuit and avoid mutual coupling interference. It will be easier to understand by combining bypass and decoupling capacitors. The bypass capacitor is actually decoupled, but the bypass capacitor generally refers to the high-frequency bypass, which is to improve a low-impedance leakage prevention way for the high-frequency switching noise.
3. Energy storage
In addition, the most important role is energy storage. The energy storage capacitor collects the charge through the rectifier and transfers the stored energy to the output of the power supply through the inverter leads. Aluminum electrolytic capacitors (such as B43504 or B43505 from EPCOS) with a voltage rating of 40 to 450 VDC and a capacitance of 220 to 150 000 μF are commonly used. Depending on the power supply requirements, devices are sometimes used in series, parallel, or a combination thereof. For power supplies with power levels exceeding 10KW, bulky can-shaped screw terminal capacitors are usually used.
Main application areas of MLCC
Compared with other ceramic capacitors, MLCC has gradually become the mainstream application of current ceramic capacitors because it can better meet the capacity requirements of modern electronic products without increasing the number and volume of components. At present, chip multilayer ceramic capacitors (MLCC) account for more than 90% of the ceramic capacitor market.
The main application areas of MLCC products are:
Consumer electronics - mobile phones, computers, tablets, cameras, smart wear, etc.
Automotive electronics - automotive, electronic products
Home appliances - LCD TVs, monitors, etc.
Among them, consumer electronics occupy more than 70% of the application space of the industry. On the smartphone side, multi-frequency bands increase the usage of passive components; the number of MLCCs in the flagship mobile phones of Apple and Samsung has exceeded 1,000. High-end smart flagship phones that support more frequency bands and are equipped with NFC modules are often equipped with a larger number of MLCCs, which expands the demand for passive components in the smart phone market.
With the in-depth development of science and technology, MLCC has gradually expanded to new energy power generation, new energy vehicles, energy-saving lamps, rail transit, DC power transmission and transformation, triple play, high-definition TV, set-top box, mobile TV and other industries.
Three Trends in MLCC
1、Miniaturization
For pocket-sized electronic products such as camcorders and mobile phones, more miniaturized MLCC products are required. On the other hand, due to the advancement of precision printed electrodes and lamination processes, ultra-small MLCC products have also gradually become available and applied. Taking the development of rectangular MLCCs in Japan as an example, the external dimensions have been reduced from 3216 in the early 1980s to 0603 now. The mainstream product of MLCC produced by domestic enterprises is Type 0603, which has broken through the technical difficulties of mass production of Type 0402 MLCC.
2、Cost Reduction
Due to the use of expensive palladium electrodes or palladium-silver alloy electrodes, 70% of the manufacturing cost of traditional MLCCs is occupied by electrode materials. The new generation of MLCCs, including high-voltage MLCCs, use cheap base metal materials such as nickel and copper as electrodes, which greatly reduces the cost of MLCCs. However, the base metal inner electrode MLCC needs to be sintered at a lower oxygen partial pressure to ensure the conductivity of the electrode material, and too low oxygen partial pressure will bring about the semiconducting tendency of the dielectric ceramic material, which is not conducive to the insulation and reliability.
3、Large capacity and high frequency
On the one hand, with the low-voltage drive and low power consumption of semiconductor devices, the operating voltage of integrated circuits has been reduced from 5 V to 3 V and 1.5 V; on the other hand, the miniaturization of power supplies requires small and large-capacity products to replace bulky aluminum Electrolytic capacitors. In order to meet the development and application of such low-voltage and large-capacity MLCCs, in terms of materials, relaxation-type high-dielectric materials with relative dielectric constants 1 to 2 times higher than BaTiO3 have been developed.
In the process of developing new products, three key technologies have been developed at the same time, namely, the technology of producing ultra-thin green sheet powder, the technology of improving the film-forming technology of the green sheet, and the technology of matching the shrinkage rate of the inner electrode and the ceramic green sheet. Recently, Japan's Panasonic Electronic Components Company has successfully developed a large-capacity MLCC with a maximum capacitance of 100 μF and a maximum withstand voltage of 25 V, which can be used in the power supply line of liquid crystal displays (LCDs).
The main advantages of MLCC are as follows:
1. Suitable for high frequency or ultra-high frequency
MLCCs have a structure that reduces resistance (ESR*1) and residual inductance (ESL*2), so normal operation is guaranteed even at high frequencies. When the frequency is higher, the impedance of the MLCC is lower, which is very beneficial to decoupling and can exert high-performance filtering ability.
2, No polarity
Can be used in circuits with very high ripple or AC circuits.
3. High security
Chip multilayer ceramic capacitors will not burn and explode even if they break down, so the safety factor is relatively high.
4. Wide range of application
MLCC can be applied to various circuits, such as oscillation circuit, timing or delay circuit, coupling circuit, decoupling circuit, smoothing filter circuit, high frequency noise suppression circuit, bypass, etc. In recent years, it has also been widely used in DC/DC converter circuits and charge pump converter circuits. The operating frequency in these power supply circuits has been increased to 1~3MHz. In this frequency range, MLCC has excellent performance. It not only reduces energy loss, ripple voltage, but also improves switching frequency, and is small in size and low in cost ( replaces tantalum electrolysis), which has important implications for portable products.
Major MLCC manufacturers
Manufacturers of MLCC products mainly include Kemet, Kyocera, Murata, Taiyo Yuden,TDK Corporation, Samsung Electro-Mechanics,Walsin, Yageo, etc.
