Murata Manufacturing Co., Ltd.

Kenjiro Mihara

Hideaki Niimi

Yuichi Takaoka

Atsushi Kishimoto

Takashi Shikama

Yutaka Ikeda

A multilayer thermistor with a positive temperature coefficient is manufactured by stepof forming a green laminate having thermistor green layers and internal electrode layers, stepof heat-treating this laminate at a temperature in the range of from 80 to less than 300&#xb0; C., stepof performing dry-barrel polishing for the heat-treated green laminate, stepof forming external electrode films on respective end surfaces of this laminate, and stepof firing this laminate together with the individual electrode films. According to this method, a highly reliable multilayer thermistor with a positive temperature coefficient can be stably manufactured.

Method for manufacturing multilayer ceramic electronic component

A multilayer ceramic electronic component includes a skittered laminated body including internal electrodes that have a strength that is greater than that of ceramic layers provided therein. End portions of the internal electrodes protrude from end surfaces of the laminated body and are deformed so as to extend along the end surfaces by a barrel polishing process using balls. When external electrodes are formed on the end surfaces of the laminated body, a large contact area with the internal electrodes can be obtained. Therefore, a reliability of the electrical connection between the electrodes is definitely secured.

Multilayer ceramic electronic components and method for manufacturing the same

A positive temperature coefficient thermistor has a non-heating portion which is not heated when a voltage is applied between first and second internal electrodes. The non-heating portion is provided in the approximate center of the positive temperature coefficient thermistor and is arranged to extend along a direction that is substantially perpendicular to a lamination direction of the positive temperature coefficient thermistor. The non-heating portion is arranged at least in the approximate center in the lamination direction of the portion of the laminate where the first and the second internal electrodes are arranged. Thus, a hot spot is reliably prevented from occurring inside the laminate when voltage is applied. As a result, the withstand voltage property is greatly improved. The non-heating portion may include a cavity provided in at least one thermistor layer or an opening or cut portion provided in the internal electrode.

Laminate-type positive temperature coefficient thermistor

An NTC thermistor has an electrically insulating substrate, a temperature-sensitive film on a surface of the substrate containing oxide of rare earth elements such as LaCoO as its principal component by at least 50 weight %, and a pair of electrodes which are separated from each other and are each electrically connected to this film. An NTC thermistor chip is obtained by further forming a pair of outer electrodes which are each on a corresponding end portion and electrically connected to a corresponding one of the surface electrodes.

NTC thermistors and NTC thermistor chips

An NTC thermistor is formed with a planar NTC thermistor element, a pair of power-supply terminals and a case which encloses the thermistor element and the terminals inside. The planar NTC thermistor has electrodes formed on a mutually opposite pair of side surfaces and each contacted by one of the power-supply terminals. At least one of the main surfaces of the planar NTC thermistor makes a surface-to-surface contact with an inner wall of the case such that the effective thermal capacity of the thermistor element is increased. Such an NTC thermistor, when inserted in series between an electrical power source and an electrical heat source, say, of an electronic copier, can effectively suppress rush currents when the power source is switched on.

NTC thermistors

A PTC thermistor element for a heating device has a main body of a layered structure having a thinner layer and a thicker layer, sandwiched between electrodes formed on the main outer surfaces facing away from each other. The thinner layer has a thickness 0.05-0.43 times that of the thicker layer and is made of a PTC thermistor material with a Curie temperature which is lower than that of the thicker layer by 20.degree. C. or more. The center of heat generation is thus shifted towards the electrode formed on the thinner layer, and a heating plate contacting it can be effectively heated.

PTC thermistor elements and heating devices incorporating same

A rush current suppression circuit suppresses a peak value of a rush current flowing into a heater. The rush current suppression circuit includes a parallel circuit formed by a positive-characteristic thermistor and a negative-characteristic thermistor. The negative-characteristic thermistor has a resistance at a normal temperature higher than that of the positive-characteristics thermistor. The parallel circuit is connected in series to the heater.

Rush current suppression circuit

A ceramic element is formed by a rare earth and transition element oxide such as LaCoO.sub.3. The ceramic element is substantially isolated from the atmosphere by a case base, a case, etc.

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Yokaichi, Japan

Kenjiro Mihara