Murata Manufacturing Co., Ltd.

Wataru Aoto

Atsushi Kishimoto

Akinori Nakayama

Hayato Katsu

Yasuhiro Nabika

Yumin Saigo

A laminated PTC thermistor element that includes a ceramic substrate including a plurality of ceramic layers, a plurality of internal electrodes within the ceramic substrate, and external electrodes on the surface of the ceramic substrate that provide electrical conduction to the internal electrodes. The ceramic substrate is 0.3 [&#x3bc;m] or more and 1.2 [&#x3bc;m] or less in average porcelain grain size. Furthermore, the relative density of the ceramic substrate has a lower limit of 70 [%], and an upper limit of &#x2212;6.43d+97.83 [%] when the average porcelain grain size is denoted by d.

Laminated PTC thermistor element

A semiconductor ceramic and a positive-coefficient characteristic thermistor are provided which have a stable PTC characteristic, a high double point, and a wide operating temperature range. The semiconductor ceramic contains, as a main component, a barium titanate-based composition having a perovskite structure expressed by a general formula ABO. Out of 100 mol % of the Ti, an amount in a range of 0.05 mol % or more to 0.3 mol % or less of Ti is replaced with W as a semiconductor forming agent, the ratio m of A sites mainly to B sites is 0.99&#x2266;m&#x2266;1.002, and an actually-measured sintered density is 70% or more and 90% or less of the theoretical sintered density. In the positive-coefficient characteristic thermistor, a component body is formed of the semiconductor ceramic.

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Nagaokakyo, Japan

Wataru Aoto