Ⅰ. What is Multilayer Ceramic Capacitors？
Ⅱ. MLCC structure
Ⅲ. MLCC manufacturing
Ⅳ. The characteristics of MLCC
Ⅴ. Advantages and disadvantages of MLCC
Ⅵ. MLCC performance
Ⅶ. Industry prospect
Ⅷ. Development trends of MLCC
Ⅰ. What is Multilayer Ceramic Capacitors？
Multilayer Ceramic Capacitors (MLCC ) is one of the main passive chip components in the electronic machine. It was born in the 1960s and was first successfully developed by an American company. Later, it was rapidly developed and industrialized by Japanese companies (such as Murata, TDK, Taiyo Yuden, etc.), and it still maintains an advantage in the global MLCC field. The main performance is that the produced MLCC has the characteristics of high reliability, high precision, high integration, high frequency, intelligence, low power consumption, large capacity, miniaturization and low cost.
It is a new type of surface mount component, which is the basic component of a new generation of communication and information terminals. It is an electronic component developed along with mobile communication, global satellite positioning system, wireless broadband, satellite broadcasting equipment, digital transmission system and other industries, and has been widely used in microwave communication circuits and optical communication circuits. MLCC electronic components are also widely used in civilian technology and military fields related to national security. They are irreplaceable key electronic components in military equipment such as missiles, phased radars, military satellites, and advanced fighters.
Multilayer ceramic capacitors are capacitors made by stacking the ceramic dielectric diaphragms of the inner electrodes in a dislocation manner, forming a ceramic chip through one-time high-temperature sintering, and then sealing the metal layer (external electrode) at both ends of the chip.
1. Material selection
(1) End pulp: it is an important factor for product performance. If the terminal paste is not selected properly, the electrical and mechanical properties of the produced terminal electrode will be low.
(2) Imported materials: North American medium-temperature sintered porcelain powder and Japanese high-temperature sintered porcelain powder are relatively mature. Domestic materials: Class I low K value porcelain powder is more mature.
(3) Porcelain powder: it is the decisive factor for the level of product quality. The use of technically immature porcelain powder materials will have major hidden dangers of quality accidents.
(4) Inner slurry: it is the key factor of product quality level, and the basic requirement is a good match with porcelain powder materials. If the MLCC is made of an inner slurry that is poorly matched with the porcelain powder material, its reliability will be greatly reduced.
2. Process flow
Multilayer ceramic capacitors have two characteristics: high frequency characteristics and temperature characteristics. Multilayer ceramic capacitors have good high-frequency characteristics, low ESR and low ESL. The temperature characteristic means that the capacitance of a multilayer ceramic capacitor changes with temperature.
1. High frequency characteristics of ceramic capacitors
The capacitor is not an ideal capacitor, it also has an equivalent series resistance ESR and an equivalent series inductance ESL. An ideal capacitor has no ESR and ESL. Compared with other types of capacitors, multilayer ceramic capacitors have excellent high-frequency characteristics, with low ESR and ESL, which can effectively reduce resistance and residual inductance, so that they can still guarantee good working performance in high-frequency circuits. At the same time, its low impedance at high frequency is beneficial to achieve decoupling effect and give full play to high-performance filtering capabilities.
2. Temperature characteristics of ceramic capacitors
Ceramic capacitors are divided into temperature-compensated ceramic capacitors and high-inductance ceramic capacitors according to temperature characteristics. Due to different temperature conditions, the capacitance of ceramic capacitors varies with temperature.
Temperature-compensated capacitors: The capacitance change rate caused by temperature changes is small. As the temperature changes, the capacitance value remains basically unchanged. Moreover, it has small capacitance loss in a high temperature and high frequency environment, and is suitable for resonant circuits and circuits that need to compensate for excessive effects, as well as places that require low loss or high stability of capacitance.
High dielectric constant type ceramic capacitor: BaTiO3 ferroelectric material barium titanate is used as the dielectric, with high relative dielectric constant at room temperature, small volume and large capacity. As the temperature changes, the capacitance change rate is large, and the relative permittivity also changes. Therefore, when used in circuits, we need to first determine the state in the electronic circuit.
Ⅴ. Advantages and disadvantages of MLCC
(1) It will not burn and explode when it breaks down, so it has high safety.
(2) Non-polarity, can be used in circuits with very high ripple or AC circuits.
(3) It does not need a large derating when used in low-impedance circuits.
(4) Due to the superimposed structure of multi-layer dielectric, the inductance is very low at high frequency, and it has a very low equivalent series resistance, so it can be used in high frequency and very high frequency circuit filtering.
(1) Poor toughness, easy to break when squeezed.
(2) For non-Class 1 capacitors, the capacitance changes greatly with temperature.
(3) The volume ratio is small, and the capacity is not as large as tantalum capacitors and aluminum capacitors.
1. Several parameters worthy of attention
(1) ESL: Equivalent Series Inductance
(2) ESR: Equivalent Series Resistance
(3) TCC: Temperature Capacitance Characteristics
2. Conventional electrical properties
(1) Capacity and error: the maximum deviation range allowed between the actual capacitance and the nominal capacitance. The capacity errors generally used are: J grade ±5%, K grade ±10%, M grade ±20%. Precision capacitors have smaller allowable errors, while electrolytic capacitors have larger errors, and they use different error levels. Commonly used capacitors have the same precision rating as resistors. Expressed in letters: Grade D—±0.5%; Grade F—±1%; Grade G—±2%; Grade J—±5%; Grade K—±10%; Grade M—±20%.
(2) Rated operating voltage: The maximum DC voltage that a capacitor can withstand in a circuit that can work stably and reliably for a long time, also known as withstand voltage. For devices with the same structure, medium, and capacity, the higher the withstand voltage, the larger the volume.
(3) Insulation resistance (IR): It is used to indicate the size of leakage. Generally, the insulation resistance of small-capacity capacitors is very large, in the hundreds of megaohms or several gigaohms. The insulation resistance of electrolytic capacitors is generally small. Relatively speaking, the larger the insulation resistance, the better, and the smaller the leakage. Generally C0G type >1000ΩF, X7R and Y5V type >500ΩF.
(4) Loss: Under the action of an electric field, the energy consumed by the capacitor to generate heat per unit time. These losses mainly come from dielectric loss and metal loss. We usually use the loss tangent value to express.
(5) Frequency characteristics: The nature of the electrical parameters of the capacitor changing with the frequency of the electric field. For capacitors working under high frequency conditions, since the dielectric constant is smaller at high frequencies than at low frequencies, the capacitance also decreases accordingly. Losses also increase with frequency. In addition, when working at high frequency, the distribution parameters of the capacitor, such as the resistance of the electrode, the resistance between the lead and the electrode, the self-inductance of the electrode, and the inductance of the lead will affect the performance of the capacitor. All of these make the frequency of use of capacitors limited.
The maximum frequency of use of different types of capacitors is different. Small mica capacitors are within 250MHZ; disc type ceramic capacitors are 300MHZ; round tube type ceramic capacitors are 200MHZ; disc type ceramic capacitors can reach 3000MHZ; small paper capacitors are 80MHZ; medium paper capacitors are only 8MHZ.
Ⅶ. Industry prospect
1. 5G communication field
With the continuous upgrading of communication standards, the substantial increase in communication frequency bands will also bring about a surge in demand for MLCC. At present, major countries and regions around the world have proposed 5G trial plans and commercial timetables to jointly promote the development of global 5G standards and industries.
The MLCC requirements brought about by 5G communications fall into two categories. The first is the demand for base stations. 5G has high-frequency and short-wave characteristics, and the transmission distance is shortened. We must add more base stations to ensure coverage. The number of base stations laid is more than double that of 4G base stations, and the increase in communication equipment will increase the demand for MLCC. Secondly, 5G is expected to add a large number of new frequency bands based on the existing frequency bands of 2G-4G. At the same time, carrier aggregation technology also increases the demand for new frequency bands. The increase in the frequency band has the greatest impact on the structure of mobile phones is the radio frequency end of the mobile phone. As the number of RF front-ends increases, the usage of stand-alone MLCC will also increase, thereby expanding the demand for MLCC.
2. The field of consumer electronics
The growth in demand for electronic components such as MLCC mainly depends on the development of the downstream consumer electronics market. In the past decade or so, the rapid popularization of smartphones has been the most important driving force for the growth of electronic components such as MLCC. However, the growth rate of the smartphone market has declined in recent years after experiencing rapid growth, and the overall scale has stabilized and entered the stock market stage. With the advent of cloud computing, big data, 5G and other technological waves, smartphones will be more widely used in smart homes, game entertainment, smart cities and other scenarios.
With the continuous upgrading of the functions of smartphone products, the usage of stand-alone MLCC is increasing. Taking the iPhone as an example, according to the data from the China Electronic Components Industry Association, the number of MLCC used in a single iPhone5S is about 400, that of the iPhone6 is about 780, that of the iPhone7 is about 850, that of the iPhone8 is about 1,000, and that of the iPhoneX is about 1,100. The proportion of high-end MLCC continues to grow, and the demand for MLCC in smartphones is expected to continue to increase in the future. And the functional upgrade of the iPhone represents a change in the industry chain, thereby expanding the demand for MLCC. At the same time, due to the increasing demand for thinner and lighter smartphones, MLCC is also developing towards miniaturization and high capacity. Ultra-small, high-capacity MLCC is increasingly used in high-end models, and their demand is expected to increase significantly. Therefore, although smartphones have entered the stock market, with technological breakthroughs, high-end smartphones will bring customers a better user experience, which will continue to drive the increase in demand for MLCC.
3. Automotive electronics field
As one of the important application fields of electronic components such as MLCC, the demand for electronic components such as MLCC in the automotive electronics industry is mainly reflected in two aspects: the increase in the rate of automotive electronics and the rapid development of the field of new energy vehicles.
① The impact of the rapid development of new energy vehicles on the demand for MLCC
MLCC is usually used in multiple links such as power engine, steering engine, idle stop, regenerative braking, engine drive, etc. The amount of MLCC used in different models varies greatly. According to the data from the China Electronic Components Industry Association, the new energy of automobiles has increased the number of MLCC per vehicle from 1,000-3,000 to 3,000-6,000, and up to 10,000. Among them, the MLCC increment brought by the power system is the largest. According to Murata's data, the number of MLCC used in electric vehicle power systems is 2,700-3,100, and they are mainly high-end products. The number of MLCC used in traditional fuel vehicle power systems is 450-600, and they are all conventional products.
② The impact of the increase in the rate of automotive electronics on the demand for MLCC
Automotive electronic products include car body electronic control devices and vehicle electronic control devices, including satellite positioning systems, central control systems, radio navigation systems, body stability control systems, etc., which help to improve the safety, comfort and economy of automobiles. sex and entertainment. It is expected that the value proportion of automotive electronic equipment in low-end and mid-to-high-end cars will increase in the future. Different from consumer electronics products, automotive electronics has higher safety requirements, and progress in this field has also continuously promoted the development of electronic components such as MLCC in the direction of high-end and refined.
With the development of information technology and the acceleration of intelligent processes such as automotive driverless technology, the automotive industry and the Internet industry continue to integrate, and the trend of increasing the rate of automotive electronics will continue in the future, thereby driving the continuous release of market demand for MLCC.
Ⅷ. Development trends of MLCC
1. 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 5V to 3V and 1.5V. On the other hand, the miniaturization of power supplies requires small and large capacitance crystal products to replace bulky aluminum electrolytic capacitors. In order to meet the development and application of this kind of low-voltage large-capacity MLCC, in terms of materials, we have developed a high-relaxation high-dielectric material with a relative permittivity 1~2 times higher than that of BaTiO3.
For pocket-sized electronic products such as camcorders and mobile phones, we need more miniaturized MLCC products. On the other hand, due to the advancement of precision printed electrodes and stacking processes, ultra-small MLCC products have gradually appeared and been applied.
3. Low cost
Due to the use of expensive palladium electrodes or silver alloy electrodes in traditional MLCC, 70% of its manufacturing costs are taken up by electrode materials, and a new generation of MLCC including high-voltage MLCC. It uses metal materials nickel and copper as electrodes, which greatly reduces the cost of MLCC, but the metal inner electrode 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 The semiconducting tendency of dielectric ceramics is not conducive to the insulation and reliability of components.