Dielectric medium of ceramic capacitor and preparation method thereof

Abstract

The invention provides a dielectric medium of a ceramic capacitor, which is prepared from the following raw materials in percentage by weight: 54 to 91 percent of BaTiO3, 2 to 13 percent of SrTiO3, 2 to 15 percent of BaZrO3, 0.05 to 1 percent of Nb2O5, 0.03 to 1.0 percent of CeO2, 0.1 to 1.0 percent of ZnO, 0.03 to 1.0 percent of Co2O3, and 2 to 15 percent of BaSiO3. The invention also provides apreparation method of the dielectric medium of the ceramic capacitor. The dielectric medium of the ceramic capacitor has high dielectric constant and high withstand voltage, generates no pollution tothe environment in the process of preparation and use, and can reduce the cost of the ceramic capacitor, so the dielectric medium is suitable for preparing monolithic ceramic capacitors and multilayer chip ceramic capacitors.

Description

technical field [0001] The invention relates to a dielectric of a capacitor, in particular to a dielectric of a ceramic capacitor and a preparation method thereof. Background technique [0002] Color TV, computer, communication, aerospace, missile, navigation and other fields urgently need ceramic capacitors with high breakdown voltage, good temperature stability, high reliability, miniaturization and large capacity. In order to realize the miniaturization and large capacity of ceramic capacitors, the dielectric of ceramic capacitors is required to have a high dielectric constant; in order to achieve a high breakdown voltage of ceramic capacitors, the dielectric withstand voltage of ceramic capacitors is required to be high; at the same time, with people's health and The increasing attention to environmental protection requires that the dielectric of ceramic capacitors will not cause harm to the human body and the environment during the process of preparation, use and dispos...

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Problems solved by technology

Another example is the Chinese Invention Patent Application Publication Note CN1212443A (the name of the invention is "high dielectric high performance medium temperature sintered chip type multilayer ceramic capacitor ceramic material", the patent application number is 97117286.2), although the disclosed ceramic capacitor ceramic material has a dielectric constant High (dielectric constant ≥ 16000), but poor withstand voltage (withstand voltage 700V / mm), and its components contain a certain amount of lead

Also have, Chinese invention patent application public specification CN1212444A (invention name is " high-performance mid-temperature sintered chip type multilayer ceramic dielectric capacitor ceramic material ", and the patent application number is 97117287.0), the disclosed capacitor ceramic material dielectric constant is too small (dielectric The electric constant is 3000), the dielectric loss is less than 1.5%, and the withstand voltage is low (the withstand voltage is 860V / mm), and its components contain a certain amount of lead

[0004] Although the dielectric of some ceramic capacitors does not contain lead, it is less harmful to the human body and the environment during the production, use and disposal of ceramic capacitors, but its dielectric constant is too small and / or the withstand voltage is low

For example, the Chinese journal "Electronic Components and Materials" in the fifth issue of 1989 in "High Dielectric High Voltage 2B 4 A kind of high-voltage ceramic capacitor dielectric material is disclosed in the dielectric ceramic " article, and the dielectric constant of this dielectric material is too small (dielectric constant ε=2500-2600), tgδ=0.5-1.4%, and voltage resistance is relatively poor (DC The compressive strength is 7KV / mm)

Another example is the Chinese Invention Patent Application Publication Specification CN1306288A (the name of the invention is "a high-voltage ceramic capacitor dielectric", and the patent application number is 00112050.6). Although the disclosed capacitor ceramic dielectric is a lead-free dielectric material, its DC withstand voltage can reach 10kV / mm Above, but the dielectric constant is too small (dielectric constant is 1860-3300), and the sintering temperature is higher (sintering temperature is 1260-1400°C)

In addition, the Chinese invention patent application publication specification CN1619726A (invention name is "a medium-low temperature sintered high-voltage ceramic capacitor medium", the patent application number is 200410041863.x), the weight percentage content of each component is: BaTiO 3 60-90%, SrTiO 3 1-20%, CaZrO 3 0.1-10%, Nb 2 o 5 0.01-1%, MgO 0.01-1%, CeO 2 0.01-0.8%, ZnO 0.01-0.6%, Co 2 o 3 0.03-1%, bismuth-lithium solid solution 0.05-10%, the dielectric constant is 2000-3000, the withstand voltage is above 6kV / mm, the dielectric constant and withstand voltage are still not ideal

[0005] In summary, the existing dielectrics for ceramic capacitors cannot meet the requirements of high dielectric constant, high withstand voltage and environmental protection at the same time.

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