Murata Manufacturing Co., Ltd.

Ikuya Taniguchi

Masahiko Kawase

Hidenobu Kimoto

Norimitsu Kito

Norimitsu Kitoh

Ryoichi Urahara

A thermistor chip is made by first forming first metal layers with a three-layer structure at both end parts of a thermistor block and then forming second metal layers with a three-layer structure on the first metal layers so as to have edge parts that are formed directly in contact with a surface area of the thermistor block and will reduce its normal temperature resistance value. The first and second metal layers are each of a three-layer structure with a lower layer made of a metal with resistance against soldering heat, a middle layer made of a metal with both wettability to solder and resistance against soldering heat, and an upper layer made of a metal having wettability to solder.

Methods of making thermistor chips

Electrodes on both ends of a thermistor chip element each have a first metal layer formed on the thermistor chip element and a second metal layer which has a smaller area than the first metal layer and is formed on the first metal layer such that the mutually opposite edge parts of the first metal layers are exposed. Third metal layers are formed over the second metal layers. A fourth metal layer may be formed between the first and second metal layers.

Thermistor chips and methods of making same

After a plurality of electronic devices such as thermistor elements are produced, each having electrodes formed on the surface of a ceramic body, they are separated into groups according to their measured resistance values. Those with resistance values smaller than a specified allowable range are repaired, having their electrodes abraded such that their resistance values are increased and brought into the specified allowable range.

Method of producing electronic devices with uniform resistance values

A thermistor chip is made by first forming first metal layers with a three-layer structure at both end parts of a thermistor element and then forming second metal layers with a three-layer structure on the first metal layers so as to have edge parts that are formed directly in contact with a surface area of the thermistor element and will reduce its normal temperature resistance value. The first and second metal layers are each of a three-layer structure with a lower layer made of a metal with resistance against soldering heat, a middle layer made of a metal with both wettability to solder and resistance against soldering heat, and an upper layer made of a metal having wettability to solder.

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Shiga, Japan

Ikuya Taniguchi