Kyocera Corporation

Youichi Yamazaki

Yoshihiro Fujioka

Daisuke Fukuda

Hideyuki Osuzu

Yoshihiro Nakao

Kiyoshi Matsubara

Kousei Kamigaki

Naoki Kikuchi

Yumiko Itoh

Yusuke Azuma

Hiromi Seki

A film capacitor includes a main body portion and external electrodes. The main body portion includes a dielectric film and a metal film that is disposed on one surface of the dielectric film. The metal film has surface roughnesses of Sand Swhere Sdenotes a surface roughness of the metal film in a first direction, and Sdenotes a surface roughness of the metal film in a second direction. The first direction is perpendicular to the second direction. Sis greater than S. The main body portion includes a pair of ends in the first direction thereof. The external electrodes are disposed on the pair of ends in the first direction of the main body portion, respectively. An average value of fractal dimensions of irregularity boundary lines due to wrinkles of the metal film is 1.08 or more.

Film capacitor, combination type capacitor, inverter, and electric vehicle

A film capacitor includes a body including a core body formed of an insulating material and metalized films which are wound around the core body; and first and second terminal electrodes disposed on both end surfaces in an axial direction of the body, respectively, a cross section perpendicular to an axial direction, i.e., z direction, of the core body having an oval outer periphery having a major axis and a minor axis, and an inner periphery defining a slit extending along the major axis. The provision of the core body makes it possible to suppress loosening of the metalized films or occurrence of a gap between the metalized films, thus making the film capacitor having a high insulation property.

A dielectric ceramic exhibiting a high dielectric constant is provided. The relative dielectric constant of the dielectric ceramic is stable with respect to temperature dependence and exhibits insulation resistance having a reduced voltage dependence. The dielectric ceramic of the invention can be used to form a multilayer ceramic capacitor that has a long life.

Dielectric ceramics and multilayer ceramic capacitor

A crystal constituting a dielectric porcelain, comprised of a first crystal group composed of crystal grains of 0.2 atomic % or less calcium concentration and a second crystal group composed of crystal grains of 0.4 atomic % or more calcium concentration, wherein the ratio of concentration of each of magnesium and a first rare earth element contained in a center portion to that contained in a surface layer portion of crystal grains constituting the first crystal group is greater than the corresponding concentration ratio of crystal grains constituting the second crystal group, and wherein on a polished surface resulting from polishing of the surface of the dielectric porcelain, when the area of crystal grains of the first crystal group is referred to as a and the area of crystal grains of the second crystal group referred to as b, the ratio of b/(a+b) is in the range of 0.5 to 0.8.

Laminated ceramic capacitor

To provide a dielectric ceramics achieving a high insulation resistance even at a low applied voltage, and minimizing insulation resistance drop when the voltage is increased, and also provide a multilayer ceramic capacitor including the dielectric ceramics as a dielectric layer, and having excellent life characteristics in a high temperature load test. The dielectric ceramics has crystal grains composed mainly of barium titanate and containing vanadium, and a grain boundary phase existing between the crystal grains. The dielectric ceramics contains 0.0005 to 0.03 moles of vanadium in terms of VO, with respect to 1 mole of barium constituting the barium titanate. In the X-ray diffraction chart of the dielectric ceramics, the diffraction intensity of (004) plane indicating the tetragonal system of barium titanate is larger than the diffraction intensity of (400) plane indicating the cubic system of barium titanate.

Disclosed is a multilayer ceramic capacitor which has a dielectric ceramic having a dielectric layer, wherein the dielectric layer mainly comprises barium titanate, contains a crystalline particle having an average crystal diameter of 0.15 to 0.3 &#x3bc;m, and contains Mg in an amount of 0.5 to 2 parts by mol in terms of MgO, Mn in an amount of 0.2 to 0.5 part by mol in terms of MnO, and a first rare earth element (RE) selected from Ho, Y, Er, Tm, Yb and Lu and a second rare earth element (RE) selected from Sm, Eu, Gd, Tb and Dy in a total amount of 0.7 to 3 parts by mol in terms of REOrelative to 100 parts by mol of barium titanate, the crystalline particle contains the first rare earth element and the second rare earth element in such a manner that the amount of the first rare earth element is larger than that of the second rare earth element, and the density gradients of the first rare earth element and the second rare earth element in the crystalline particle as determined from the particle boundary toward the center of the crystalline particle are &#x2212;0.005 to &#x2212;0.05 atm %/mm and &#x2212;0.0005 to &#x2212;0.005 atm %/mm, respectively. Also disclosed is a method for producing the multilayer ceramic capacitor.

Multilayer ceramic capacitor and method for production thereof

The invention relates to a multilayer ceramic capacitor having dielectric layers and internal electrode layers disposed alternately. The dielectric layers include a dielectric ceramic containing barium titanate as a main component, and also calcium, magnesium, vanadium, manganese, and a rare-earth element. Crystals constituting the dielectric ceramic are constituted by grains containing barium titanate as their main component and containing calcium in a concentration of 0.2 atomic % or less or containing the calcium in a concentration of 0.4 atomic % or more. The crystals grains are also distinct in their relative distributions of magnesium and rare-earth elements between the center of the grain and the surface of the grain. Finally, the relative areas of the two kinds of crystals observed in the plane of a polished surface of the dielectric ceramic are described by a ratio b/(a+b), which is 0.5 to 0.8.

Multilayered ceramic capacitor

A multilayer ceramic capacitor includes a plurality of ceramic dielectric layers, a plurality of inner electrode layers and and external electrodes. The ceramic dielectric layers includes barium titanate crystal grains having pores inside. The inner electrode layers are between the ceramic dielectric layers. The external electrodes are electrically connected to the inner electrode layers. The barium titanate crystal grains each have a core-shell structure which include a core and a shell around the core. The the pores are mainly formed in the cores.

Multilayer ceramic capacitor

Crystal grains mainly composed of barium titanate have a mean grain size of not more than 0.2 &#x3bc;m. The volume per unit cell V that is represented by a product of lattice constant (a, b, c) figured out from the X-ray diffraction pattern of the crystal grains is not more than 0.0643 nm. Thereby, a dielectric ceramics having high relative dielectric constant can be obtained. A multilayer ceramic capacitor comprises a capacitor body and an external electrode that is formed at both ends of the capacitor body. The capacitor body comprises dielectric layers composed of the dielectric ceramics, and internal electrode layers. The dielectric layers and the internal electrode layers are alternately laminated.

Dielectric ceramics, multilayer ceramic capacitor and method for manufacturing the same

In a chip-type electronic component of the present invention, at least one surface of a ceramic body is a convexly curved surface. Specifically, at least one surface in a thickness direction of the ceramic body may be convexly curved, and the side surface of the ceramic body may be concavely curved. Alternatively, only one surface may be a convexly curved surface. This chip-type electronic component has a high visibility and a high mechanical strength, though it is small. Moreover, in a chip-type electronic component comprising a ceramic body that is formed by alternately laminating insulating layers and conductor layers, and a pair of external electrodes, the thickness in a laminate direction at the central part between external electrodes of the ceramic body is made greater than the thickness of the end surface. This prevents breakage of the external electrodes and also enlarges the ceramic body.

Growing community of inventors

Kirishima, Japan

Youichi Yamazaki