Multilayer ceramic capacitor (MLCC for short) is one of the main passive chip components in electronic equipment. It was born in the 1960s and was first successfully developed by an American company. Later, Korean companies (such as Murata, TDK, Taiyo Yuden, etc.) developed and industrialized rapidly. So far, it is expected to maintain its advantages in the MLCC field, mainly manifested in the characteristics of high reliability, high precision, high integration, high frequency, intelligence, low cost, large capacity, miniaturization and high-end.

MLCC - short for capacitor, is formed by a ceramic dielectric film with printed electrodes (inner electrodes) in the right way, and then a ceramic chip is formed by a one-time high-temperature sintering, and then a metal layer (outer electrode) is sealed at both ends of the chip to form a structure similar to a monolith, so it is also called a monolithic capacitor.

In addition to the common characteristics of capacitors "blocking DC and passing AC", MLCC also has the characteristics of small size, large capacity, long life, high reliability, and suitable for surface mounting. With the rapid development of the world's electronics industry, as the basic component of the electronics industry, chip capacitors are also developing at an astonishing speed, increasing at a rate of 10% to 15% per year. At present, the world's demand for chip capacitors is more than 200 billion, 70% of which come from Japan (such as MLCC giant Murata), followed by Europe, America and Southeast Asia (including China). With the improvement of the reliability and integration of chip capacitor products, its scope of use is becoming wider and wider, and it is widely used in various military and civilian electronic equipment and electronic equipment, such as computers, telephones, program-controlled switches, precision test instruments, radar communications, etc.

The basic principle is that it consists of an insulating middle layer plus two conductive metal electrodes

MLCC has also developed rapidly: the types are increasing, the volume is shrinking, the performance is improving, the technology is advancing, the materials are constantly updated, and the thin and short series of products have tended to be standardized and universal. Its application has gradually penetrated and developed from consumer equipment to investment equipment. Mobile communication equipment uses chip components in large quantities.

With the rapid development of the world's electronic information industry, the development direction of MLCC is as follows:

1. In order to meet the needs of portable communication tools, chip multilayer capacitors are also developing towards low voltage, large capacity, ultra-small and ultra-thin.

2. In order to adapt to the development of some electronic equipment and electronic equipment towards high power and high withstand voltage (mostly military communication equipment), high withstand voltage, high current, high power, ultra-high Q value and low ESR type medium and high voltage chip capacitors are also the most common development direction.

3. In order to meet the requirements of highly integrated lines, multifunctional composite chip capacitors (LTCC) are becoming a hot spot in technical research.

Main materials and core technologies of MLCC and characteristics of LCC

1. Material technology (preparation of ceramic powder)

Ceramic powder for MLCC is now mainly divided into three categories (Y5V, X7R and COG). Among them, X7R material is the most competitive specification among countries, and it is also one of the varieties with the largest market demand and electronic equipment consumption. Its manufacturing principle is based on the modification of nano-level barium titanate ceramic material (BaTiO3). Japanese manufacturers (such as Murata) add rare earth metal oxides to the wet BaTiO3 with a D50 of 100 nanometers to produce high-reliability X7R ceramic powders based on the demand for large capacity (above 10μF), and finally produce 10μF-100μF small-size (such as 0402, 0201, etc.) MLCCs. Domestic manufacturers add rare earth metal oxides to BaTiO3 with a D50 of 300-500 nanometers to produce X7R ceramic powders, which is still a long way from the advanced powder technology abroad.

2. Multilayer dielectric thin film technology (multilayer dielectric)

Since manufacturing MLCC with higher capacitance value based on small sizes such as 0805, 0603, and 0402 has always been one of the important topics in the MLCC industry, with the continuous improvement of materials, processes and equipment levels in recent years, Japanese companies have stacked 1000 layers of process practice on 2μm thin film dielectrics, and produced 100μF MLCC with a single-layer dielectric thickness of 1μm, which has a lower ESR value than chip tantalum capacitors and a wider operating temperature (-55℃-125℃). Fenghua Hi-Tech, which represents the highest level of MLCC manufacturing in China, can complete the casting of 3μm thick thin film dielectrics and execute MLCC with 2μm thick dielectrics after porcelainization, which is still a certain distance from the advanced layer printing technology abroad. Of course, in addition to the powder that can be used for multi-layer dielectric thin film layer printing, the automation and accuracy of the equipment need to be improved.

3. Co-firing technology (co-firing of ceramic powder and metal electrode)

The structural basis of MLCC components consists of three metal layers: ceramic dielectric, inner electrode metal layer and outer electrode. MLCC is made of multi-layer ceramic dielectric printed with internal electrode slurry and co-fired. To this end, it is inevitable to solve the problem that ceramic dielectrics and internal electrode metals with different shrinkage rates will not be delaminated or cracked after high-temperature firing, that is, the co-firing of ceramic powder and metal electrodes. Co-firing technology is the key technology to solve this problem. Mastering good co-firing technology can produce MLCC with thinner dielectrics (below 2μm) and higher voltage layers (more than 1000 layers). At present, Japanese companies are ahead of other countries in the technology of MLCC sintering special equipment. They not only have various nitrogen deposition kilns (bell furnaces and tunnel furnaces), but also have obvious advantages in equipment automation and precision.

Advantages of MLCC:

1. Due to the use of multi-layer dielectric superposition structure, the inductance is very low at high frequency and has a very low equivalent series resistance, so it can be used in high-frequency and high-frequency circuits without rivals

2. Non-polarity, it can be used in circuits with very high ripple or AC circuits;

3. It does not require a large reduction in rating when used in low-impedance circuits;

4. It does not burn when broken down and has high safety.