Matsushita Electric Industrial Co., Ltd.

Junji Kojima

Takashi Ikeda

Toshiyuki Iwao

Kohichi Morimoto

Kiyoshi Ikeuchi

Koichi Morimoto

Naohiro Mikamoto

Masakazu Tanahashi

Emiko Igaki

Toshiro Kume

Kouichi Morimoto

Akira Tanaka

Masahiro Ito

Masahiko Ito

Chip PTC thermistors that can easily be inspected the soldered portions after it is mounted on a printed circuit board and that can be used in a flow soldering process, and methods of making same. A chip PTC thermistor of the present invention includes: a first main electrode and a first sub-electrode on first surface of a cuboidal form conductive polymer having the PTC characteristics, a second main electrode and a second sub-electrode on a second surface opposite the first surface of the conductive polymer. Between the first sub-electrode and the second sub-electrode, and between the first sub-electrode and the second main electrode are electrically connecting with a first side electrode and a second side electrode, respectively.

Chip PTC thermistor and method for manufacturing the same

Method of manufacturing a chip PTC thermistor

A chip PTC thermistor comprising a conductive polymer having PTC properties, a first outer electrode, a second outer electrode, one or more inner electrodes sandwiched between the conductive polymer, a first electrode electrically directly coupled with the first outer electrode, and a second electrode. The odd-numbered inner electrode among the one-or-more inner electrodes is directly coupled with the second electrode, while the even-numbered inner electrode, with the first electrode. When total number of the inner electrodes is an odd number the second outer electrode makes direct electrical contact with the first electrode, when it is an even number the second outer electrode makes direct electrical contact with the second electrode. Defining a distance from the odd-numbered inner electrode to the first electrode, or from the even-numbered inner electrode to the second electrode, as &ldquo;a&rdquo;, while a distance between the adjacent inner electrodes, or a distance between the inner electrode placed the most adjacent to the first outer electrode, or the second outer electrode, and the first outer electrode, or the second outer electrode, as &ldquo;t&rdquo;; the PTC thermistors are constituted so that a ratio a/t is within 3-6. The chip PTC thermistors in accordance with the present invention effectively prevent an overcurrent in large current circuits.

PTC chip thermistor

An electrode for a PTC thermistor of the present invention includes a base layer having electrical conductivity and a sintered layer formed on the base layer. The sintered layer is formed by sintering a conductive powder and has electrical conductivity, and has roughness on a surface thereof. Thus, the present invention can provide an electrode for a PTC thermistor that has a large adhesion to the conductive polymer and can be produced easily.

Electrode for PTC thermistor and method for producing the same, and PTC thermistor

A chip PTC thermistor is provided which is capable of increasing the rate of increase in resistance when an overcurrent is applied, thereby increasing the breakdown voltage. The PTC thermistor comprises: a first main electrode and a first sub-electrode disposed on a first face of a conductive polymer with PTC properties; a second main electrode and a second sub-electrode disposed on a second face of the conductive polymer, which is facing the first face; and first and second side electrode and disposed on side faces of the conductive polymer. Cut-off sections are provided to the vicinity of joints of the first main electrode and the first side electrode, and joints of the second main electrode and the second side electrode.

Polymer chip PTC thermistor

A method of manufacturing a chip PTC thermistor utilizes a piece of conductive polymer having a PTC characteristic and metal foils formed by patterning and provided on the upper and the lower sides of the piece under pressure integrally into a sheet, making a hole part in the sheet, applying a protective coating serving as plating resist to upper and lower sides of the sheet, forming an electrode on the sheet by electroplating, and cutting the sheet into a chip. The protective coating is made of a material applicable at a temperature equal to or lower than the melting point of the conductive polymer. The processing temperatures at the step from the step of making a hole part in the sheet to the pre-processing step of the step of forming an electrode by electroplating on the sheet are not above the melting point of the conductive polymer.

Method of manufacturing chip PTC thermistor

A chip polymer PTC thermistor for surface mount assembly having a superior long-term connection reliability between side electrode and main and sub electrodes. The thermister comprises; a rectangular parallelepiped conductive polymer( ) having PTC properties; a first main electrode( ) and a first sub electrode( ) disposed on a first face of the conductive polymer; a second main electrode( ) and a second sub electrode( ) disposed on a second face opposite the first face of the conductive polymer; and first and second side electrodes( ) folding around and over the entire surface of side faces of the conductive polymer, the side electrodes electrically coupling the electrodes disposed on the two faces of the conductive polymer, and a thickness of the side electrodes is not less than one twentieth of the distance between the first main electrode( ) and the second sub electrode( ) and the distance between the first sub electrode( ) and second main electrode( ).

PTC thermister chip

The present invention aims to provide a PTC thermister which uses a conductive polymer having a positive temperature coefficient and has a high withstand voltage and high reliability and in which no failure in electrical connection occurs in side electrode even when a mechanical stress occurs due to the thermal shock by repeated thermal expansion of the conductive polymer sheet. It also aims to provide a method to manufacture the above PTC thermister. To achieve the above purpose, the PTC thermister of the present invention comprises (1)a laminated body made by alternately laminating conductive polymer sheets and inner electrodes, (2) outer electrodes disposed on tops and bottoms of said laminated body and (3) multi-layered side electrodes disposed at the center of both sides of said laminated body and is electrically coupled with said inner electrodes and said outer electrodes. And, a side of laminated body having an area on which a side electrode layer is formed and areas on which side electrode is not formed. A method for manufacturing a PTC thermistor comprises the steps of (1) forming a laminated body by sandwiching a conductive polymer sheet with metal foils, and then integrating them by heat pressing, (2) sandwiching the laminated body and conductive polymer sheets from the top and bottom by metal foils, and integrating them by heat pressing. A multi-layered PTC thermistor is obtained by repeating above processes.

PTC thermistor and method for manufacturing the same

The PTC thermistor chip of the present invention comprises a conductive polymer having PTC properties, a first outer electrode, a second outer layer electrode, not less than one inner electrode sandwiched between the conductive polymer, a first electrode electrically directly coupled with the first outer electrode, and a second electrode disposed electrically independently from the first electrode. When counting from one of the inner electrodes closest to the first outer layer electrode, and defining the inner layer electrode in a &ldquo;n&rdquo;th position as the &ldquo;n&rdquo;th inner electrode, the odd-numbered inner layer electrodes are directly coupled with the second electrode and the even-numbered inner layer electrodes, with the first electrode. In this PTC thermistor, the cross sections where the odd-numbered and even numbered inner electrodes are respectively in contact with the second and first electrodes are thicker than the other sections.

Chip PTC thermistor and method of manufacturing the same

The present invention aims to provide a PTC thermister which uses a conductive polymer having a positive temperature coefficient and has a high withstand voltage and high reliability and in which no failure in electrical connection occurs in side electrode even when a mechanical stress occurs due to the thermal shock by repeated thermal expansion of the conductive polymer sheet. It also aims to provide a method to manufacture the above PTC thermister. To achieve the above purpose, the PTC thermister of the present invention comprises (,) a laminated body made by alternately laminating conductive polymer sheets and inner electrodes, (,) outer electrodes disposed on tops and bottoms of said laminated body and (,) multi-layered side electrodes disposed at the center of both sides of said laminated body and is electrically coupled with said inner electrodes and said outer electrodes. And, a side of laminated body having an area on which a side electrode layer is formed and areas on which side electrode is not formed. A method for manufacturing a PTC thermistor comprises the steps of (,) forming a laminated body by sandwiching a conductive polymer sheet with metal foils, and then integrating them by heat pressing, (,) sandwiching the laminated body and conductive polymer sheets from the top and bottom by metal foils, and integrating them by heat pressing. A multi-layered PTC thermistor is obtained by repeating above processes.

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Hirakata, Japan

Junji Kojima