Murata Manufacturing Co., Ltd.

Mitsutoshi Kawamoto

Hideaki Niimi

Akira Ando

Masahiro Kodama

Shinsuke Tani

Ryouichi Urahara

Yukio Sakabe

Yukio Hamaji

Atsushi Kishimoto

Akinori Nakayama

Tatsuya Ishikawa

Satoshi Ueno

Yoshihiro Fujita

Yuichi Kusano

Atsushi Sano

Yuki Kimura

Yasutomo Kobayashi

A component body is obtained by alternately laminating and sintering a plurality of semiconductor ceramic layers formed of a SrTiO-based grain boundary insulated semiconductor ceramic and a plurality of internal electrode layers. The average grain diameter of crystal grains is 1.0 &#x221d;m or less and a coefficient of variation representing variations in a grain diameter of the crystal grains is 30% or less. To prepare the semiconductor ceramic an Sr compound, a Ti compound and a donor compound are weighed in predetermined amounts and mixed/pulverized. A calcined powder is prepared and a dispersant is added with an acceptor compound to the calcined powder. The resulting mixture is wet-mixed and a heat-treated powder is prepared. The heat-treated powder is formed into slurry and subjected to a filter treatment. The filtered slurry is used to prepare a semiconductor ceramic. The resulting laminated semiconductor ceramic capacitor has a varistor function having excellent durability, which can suppress a reduction of insulating properties and ensure desired electrical characteristics even when ESD occurs repeatedly.

Laminated semiconductor ceramic capacitor with varistor function and method for manufacturing the same

A ceramic powder for use in a grain boundary insulated semiconductor ceramic that has an excellent ESD withstanding voltage, a semiconductor ceramic capacitor using the ceramic powder, and a manufacturing method therefor. The ceramic powder for use in a SrTiObased grain boundary insulated semiconductor ceramic has a specific surface area of 4.0 m/g or more and 8.0 m/g or less, and a cumulative 90% grain size D90 of 1.2 &#x3bc;m or less.

Ceramic powder, semiconductor ceramic capacitor, and method for manufacturing same

A semiconductor ceramic contains a donor element solid-solved in crystal grains of a SrTiO-based compound, and an acceptor element in a grain boundary layer. The number of tetravalent acceptor elements is 1&#xd7;10/g or more, as determined from an electron spin resonance absorption spectrum. A mixture of a calcined powder and an acceptor compound is pulverized to a specific surface area of 5.0 to 7.5 m/g before mixing with a binder. Semiconductor ceramic layers having a varistor function are formed by using the semiconductor ceramic forming a highly reliable capacitor which can suppress characteristics variations to stably obtain good electrical characteristics.

Semiconductor ceramic and method for manufacturing the same, and laminated semiconductor ceramic capacitor with varistor function and method for manufacturing the same

A semiconductor ceramic having a compounding molar ratio m between a Sr site and a Ti site that satisfies 1.000 &#x2266;m&#x2266;1.020, has a donor element present as a solid solution in crystal grains, has an acceptor element present in a grain boundary layer in the range of 0.5 mol or less with respect to 100 mol of the Ti element, contains a Zr element in the range of 0.15 mol or more and 3.0 mol or less with respect to 100 mol of the Ti element, and has the crystal grains of 1.5 &#x3bc;m or less in average grain size.

Laminate type semiconductor ceramic capacitor with varistor functionality and method for manufacturing the same

A laminate type semiconductor ceramic capacitor with a varistor function is achieved which allows for an improvement in product yield while ensuring such insulation performance that can withstand practical use, and is suitable for mass production with a favorable ESD withstanding voltage. The semiconductor ceramic forming the semiconductor ceramic layers has a compounding molar ratio m between the Sr site and the Ti site of 0.990&#x2266;m&#x3c;1.000, has a donor element such as La present as a solid solution in crystal grains, has an acceptor element such as Mn present in a grain boundary layer in the range of 0.5 mol or less (preferably 0.3 mol to 0.5 mol) with respect to 100 mol of the Ti element, and has the crystal grains with an average grain size of 1.5 &#x3bc;m or less.

Laminate type semiconductor ceramic capacitor with varistor function

A SrTiO-based grain boundary insulation type semiconductor ceramic contains a donor element in solid solution in crystal grains, an acceptor element at least in crystal grain boundaries, an integral width of (222) face of the crystal face of 0.500&#xb0; or less, and an average powder grain size of crystal grains of 1.0 &#x3bc;m or less. A semiconductor ceramic is obtained by firing this ceramic, and a monolithic semiconductor ceramic capacitor is obtained by using the semiconductor ceramic. The SrTiO-based grain boundary insulation type semiconductor ceramic powder has a large apparent relative dielectric constant &#x2208;rof 5,000 or more even when the average ceramic grain size of crystal grains is 1.0 &#x3bc;m or less and which has an excellent insulating property. The monolithic semiconductor ceramic capacitor is capable of having a large capacity through reduction in thickness and multilayering.

Semiconductor ceramic powder, semiconductor ceramic, and monolithic semiconductor ceramic capacitor

A semiconductor ceramic has a mixing molar ratio m between the Sr site and the Ti site satisfying the relationship 1.000&#x2266;m&#x3c;1.020, a donor element in an amount of 0.8 to 2.0 moles relative to 100 moles of the Ti element dissolved in the Sr site to form a solid solution, the donor element having a higher valency than the Sr element, a transition metal element, such as Mn, incorporated in an amount of 0.3 to 1.0 mole relative to 100 moles of the Ti element so as to be segregated in grain boundaries, and an average grain size of crystal grains is 1.0 &#x3bc;m or less. A component body in which semiconductor ceramic layers are stacked and internal electrodesare embedded provides a SrTiO-based grain boundary insulation type semiconductor ceramic having a high apparent relative dielectric constant of 5,000 or more even if the average grain size of crystal grains is decreased to 1 &#x3bc;m or less, and a semiconductor ceramic capacitor in which it is possible to achieve both a reduction in layer thickness and improvement in dielectric characteristics by using the SrTiO-based grain boundary insulation type semiconductor ceramic.

Semiconductor ceramic and multilayered-type semiconductor ceramic capacitor

A semiconductor ceramic comprising a donor element within the range of 0.8 to 2.0 mol relative to 100 mol of Ti element contained as a solid solution with crystal grains, a first acceptor element in an amount less than the amount of the donor element is contained as a solid solution with the crystal grains, a second acceptor element within the range of 0.3 to 1.0 mol relative to 100 mol of a Ti element is present in crystal grain boundaries, and the average grain size of the crystal grains is 1.0 &#x3bc;m or less. A monolithic semiconductor ceramic capacitor is obtained by using this semiconductor ceramic. To form the semiconductor ceramic, in a first firing treatment to conduct reduction firing, a cooling treatment is conducted while the oxygen partial pressure at the time of starting the cooling is set at 1.0&#xd7;10times or more the oxygen partial pressure in the firing process. In this manner, a SrTiObased grain boundary insulation type semiconductor ceramic having a large apparent relative dielectric constant &#x2208;rof 5,000 or more and a large resistivity log &#x3c1; (&#x3c1;: &#x3a9;&#xb7;cm) of 10 or more even when crystal grains are made fine to have an average grain size of 1.0 &#x3bc;m or less, a monolithic semiconductor ceramic capacitor including the semiconductor ceramic, and methods for manufacturing them are realized.

Semiconductor ceramic, monolithic semiconductor ceramic capacitor, method for manufacturing semiconductor ceramic, and method for manufacturing monolithic semiconductor ceramic capacitor

A monolithic semiconductor ceramic capacitor includes semiconductor ceramic layers made of a semiconductor ceramic having a Sr site and a Ti site. The semiconductor ceramic satisfies the inequality 1.000&#x3c;m&#x2266;1.020, wherein m represents the molar ratio of the Sr site to the Ti site. The semiconductor ceramic contains crystal grains and has grain boundary layers. The crystal grains contain a donor element such as La or Sm in the form of a solid solution. The grain boundary layers contain an acceptor element such as Mn, Co, Ni or Cr. The amount of the acceptor element therein is equal to or less than 0.5 mol (preferably 0.3 to 0.5 mol) per 100 mol of Ti. The crystal grains have an average size of 1.0 &#x3bc;m or less (preferably 0.5 to 0.8 &#x3bc;m). Therefore, the monolithic semiconductor ceramic capacitor has good electrical properties, good resistivity, good dielectric strength, and high reliability and is suitable for thin or compact apparatuses.

Monolithic semiconductor ceramic capacitor having varistor function and method for manufacturing monolithic semiconductor ceramic capacitor

A BaTiO-type semiconducting ceramic material which has undergone firing in a reducing atmosphere and re-oxidation, wherein the relative density of the ceramic material after sintering is about 85&#x2013;90%. A process for producing the semiconducting ceramic material of the present invention and a thermistor containing the semiconducting ceramic material are also disclosed.

Semiconducting ceramic material, process for producing the ceramic material, and thermistor

A ceramic electronic component includes a component body having semiconductive ceramic layers and internal electrodes. The semiconductive ceramic layers and the internal electrodes are alternately laminated. The semiconductive ceramic layers have a relative density of about 90% or less and contain no sintering additives. The component body is provided with an external electrode on each side thereof. The ceramic electronic component has a low resistance and a high withstand voltage.

Ceramic electronic component

A method for producing a lead ferroelectric film having high relative dielectric constant and low dielectric loss by a hydrothermal process is disclosed. The method includes the step of hydrothermally forming a ferroelectric layer on a substrate, followed by the step of hydrothermally treating the resulting film in an aqueous solution having a pH of about 5 to 7.

Film production method and film-element production method

A monolithic semiconducting ceramic electronic component includes barium titanate-based semiconducting ceramic layers and internal electrode layers alternately deposited, and external electrodes electrically connected to the internal electrode layers. The semiconducting ceramic layers contain ceramic particles having an average particle size of about 1 &mgr;m or less and the average number of ceramic particles per layer in the direction perpendicular to the semiconductor layers is about 10 or more. The internal electrode layers are preferably composed of a nickel-based metal.

Monolithic semiconducting ceramic electronic component

The semiconducting ceramic material of the present invention containing BaTiO and having a positive temperature coefficient of resistance is endowed with high withstand voltage. In the semiconducting ceramic material, a boundary temperature defined at the boundary between a first temperature range and a second temperature range is 180&deg; C. or more (e.g., 370&deg; C.) higher than the Curie temperature, wherein the first temperature range is higher than the Curie temperature and the ceramic material has a positive temperature coefficient of resistance in the range, and the second temperature range is higher than the first temperature range and the ceramic material has a negative temperature coefficient of resistance in the range.

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Otsu, Japan

Mitsutoshi Kawamoto