What are the types of ceramic capacitors?
1. Semiconductor ceramic capacitor
Capacitor miniaturization means that the capacitor gets as large a volume as possible in the smallest possible volume, which is one of the trends in capacitor development. For the separation capacitor assembly, there are two basic ways of miniaturization, even if the dielectric constant of the dielectric material is increased as much as possible and the thickness of the dielectric layer is as thin as possible.
Among ceramic materials, ferroelectric ceramics have a high dielectric constant, but when ferroelectric ceramics are used to make ordinary ferroelectric ceramic capacitors, ceramic dielectrics are difficult to make very thin. First of all, because the strength of ferroelectric ceramics is low, it is easy to be broken when it is thin, and it is difficult to carry out actual production operations. Secondly, when the ceramic medium is thin, it is easy to cause various kinds of tissue defects, and the production process is very difficult.
The surface layer ceramic capacitor is a dielectric layer formed by using a very thin insulating layer formed on the surface of a semiconductor ceramic such as BaTiO3, and the semiconductor ceramic itself can be regarded as a series circuit of dielectrics. The thickness of the insulating surface layer of the surface layer ceramic capacitor fluctuates between 0.01 and 100 μm depending on the formation method and conditions. This not only utilizes the high dielectric constant of the ferroelectric ceramics, but also effectively reduces the thickness of the dielectric layer, and is an effective solution for preparing micro-miniature ceramic capacitors.
2, grain boundary layer ceramic capacitor
On the surface of BaTiO3 semiconducting ceramics with sufficient grain development, apply appropriate metal oxides (such as CuO or Cu2O, MnO2, Bi2O3, Tl2O3, etc.), heat treatment under oxidizing conditions at appropriate temperature, and coat the oxidation. The material will form a low co-solution phase with BaTiO3, rapidly diffuse into the interior of the ceramic along the open pores and grain boundaries, and form a thin solid solution insulating layer on the grain boundaries. This thin solid solution insulating layer has a high electrical resistivity (up to 1012 to 1013 Ω·cm). Although the ceramic grains are still semiconductor inside, the entire ceramic body exhibits a dielectric constant of up to 2×104 to 8×. 104 dielectric medium. A capacitor prepared using such a porcelain is referred to as a boundarg layer ceramic capacitor, abbreviated as a BL capacitor.
3, high voltage ceramic capacitor
With the rapid development of the electronics industry, it is urgent to develop high-voltage ceramic capacitors with high breakdown voltage, low loss, small size, and high reliability. In the past 20 years, high-voltage ceramic capacitors successfully developed at home and abroad have been widely used in power systems, laser power supplies, video tape recorders, color TVs, electron microscopes, photocopiers, office automation equipment, aerospace, missiles, and navigation.
Barium titanate-based ceramic materials have the advantages of high dielectric constant and good AC withstand voltage characteristics, but there are also disadvantages such as a change in capacitance with an increase in dielectric temperature and a decrease in insulation resistance. The titanate temperature of barium titanate crystal is -250 ° C, which is a cubic crystal perovskite structure at normal temperature. It is a paraelectric body, and there is no spontaneous polarization phenomenon. The dielectric constant of barium titanate-based ceramic material under high voltage. The small variation, tg δ and small rate of change in capacitance make these advantages very advantageous as high voltage capacitor dielectrics.
4, multilayer ceramic capacitor
Multilayer Ceramic Capacitor (MLCC) is the most widely used type of chip component. It is a combination of internal electrode material and ceramic body in multiple layers and is co-fired into one whole. Chip monolithic capacitors with small size, high specific capacitance and high precision, can be mounted on printed circuit board (PCB) and hybrid integrated circuit (HIC) substrates, effectively reducing electronic information terminal products (especially The volume and weight of portable products) improve product reliability. It conforms to the development direction of miniaturization, light weight, high performance and multifunction of the IT industry.
The national 2010 long-term goal outline clearly proposes new components such as surface mount components as the development focus of the electronics industry. It is not only simple in packaging, good in sealing, but also effectively isolates the opposite electrode. MLCC can play the role of storing charge, blocking DC, filtering, coordinating, distinguishing different frequencies and tuning the circuit in the electronic circuit. It can partially replace organic film capacitors and electrolytic capacitors in high-frequency switching power supplies, computer network power supplies and mobile communication devices, and greatly improve the filtering performance and anti-interference performance of high-frequency switching power supplies.
Ceramic capacitor application
1. Military industry
Military MLCC, as a basic electronic component, is used more and more in military, electronic equipment such as aviation, aerospace, military mobile communication equipment, pocket military computers, weapon warhead control and military signal monitoring, radar, artillery fuze, warships, and weapon systems. . With the digitization of China's national defense equipment, the acceleration of information construction, and the strong localization of the military industry, the market prospects for military high-reliability MLCC are very broad. In 2009, the market size of China's military MLCC products was 750 million yuan, and by 2013 it had grown to 1.44 billion yuan, nearly doubled. It is expected to maintain a stable and high growth rate in the future. It is expected to reach 3 billion in 2019. yuan.
2, industry
The industrial capacitor market mainly includes system communication equipment, industrial control equipment, medical electronic equipment, automotive electronics, precision instrumentation, and petroleum exploration equipment. Industrial equipment is developing towards mechatronics and intelligence. The application of electronic control, data analysis, and interface display information is increasing, which will provide a broad market prospect for industrial high-reliability MLCC products.
3. Consumer
The consumer market includes general consumer products and high-end consumer products. The former includes electronic products such as notebook computers, televisions, telephones, ordinary mobile phones, and ordinary digital cameras. The latter includes professional recording equipment, professional video equipment, and high-end smartphones. High-end electronic products. Compared with the demand for military and industrial MLCC products, the consumer products market has the largest demand.
From a global perspective, Japanese manufacturers have a clear lead. Among the top ten MLCC manufacturers in the world, Japanese manufacturers have a global market share of more than 40%, mainly because Japanese manufacturers are leading other countries and regions in cutting-edge high-capacity products and ceramic powder technology. Compared with well-known foreign manufacturers, domestic ceramic capacitor manufacturers are mostly small and medium-sized enterprises, and most of the products are at the middle and low level.
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