JPH09162006A - Manufacturing method of positive temperature coefficient thermistor - Google Patents

Abstract

(57) An object of the present invention is to provide a method for manufacturing a positive temperature coefficient thermistor, in which variations in resistance value are small and a temperature coefficient of resistance is large. SOLUTION: By using TiNb ₂₄ O ₆₂ as a raw material of niobium added as a semiconducting element, TiNb ₂₄ O ₆₂ is uniformly mixed at the time of mixing the raw materials, and thus the distribution of niobium atoms is uniform. Is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a characteristic that the resistance value rapidly increases at a specific temperature and is widely applied to a constant temperature heating element, a current control element, etc. It is about.

[0002]

2. Description of the Related Art A method of manufacturing a conventional PTC thermistor will be described below.

A conventional positive temperature coefficient thermistor weighs and mixes main raw materials such as barium carbonate and titanium oxide, additives such as lead oxide, aluminum oxide and silicon oxide, and a trace amount of semiconducting elements such as niobium oxide. The mixing is carried out by a wet method in order to disperse them uniformly, and calcination forms barium titanate as a main component. After that, crushing, granulation, and molding are performed by a general porcelain manufacturing method, and firing is performed in the air to obtain a desired positive temperature coefficient thermistor.

[0004]

However, in the above-mentioned conventional manufacturing method, since the amount of niobium oxide which is a semiconducting element is extremely small, it is possible to disperse the niobium oxide uniformly only by wet mixing. It is difficult, and the distribution of niobium atoms inside the PTC thermistor becomes non-uniform. Therefore, the progress of semiconductivity is likely to be heterogeneous inside, a slight difference in the firing conditions causes a large variation in the resistance value at room temperature, and the resistance temperature coefficient α at a temperature at which the resistance value sharply increases. There was a problem that it was difficult to obtain a large one.

The present invention solves the above-mentioned problems of the prior art by making the distribution of niobium atoms inside the PTC thermistor uniform and reducing the variation in resistance value.
An object of the present invention is to provide a manufacturing method capable of obtaining an excellent positive temperature coefficient thermistor having a large temperature coefficient of resistance α.

[0006]

In order to achieve this object, the method for producing a positive temperature coefficient thermistor of the present invention uses TiNb ₂₄ O ₆₂ as a raw material of niobium used as a semiconductor element.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION TiN according to claim 1 of the present invention
By using b ₂₄ O ₆₂ , when a certain amount of niobium is added, the amount of the niobium compound can be increased because the volume of the niobium compound is larger than that in the conventional method of adding only niobium oxide. It becomes easy to uniformly mix a small amount of additive niobium. Therefore, even in the PTC thermistor porcelain after firing, the niobium atoms are evenly distributed, the variation of the resistance value is reduced, and the resistance temperature coefficient is also increased.

[0008]

An embodiment of the present invention will be described below. In this embodiment, the compositional formula of the positive temperature coefficient thermistor (Formula 1) is used.
In, the positive temperature coefficient thermistor porcelain with various x values was manufactured as follows.

[0009]

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First, barium carbonate, lead oxide, titanium oxide, niobium oxide, titanium niobate, silicon oxide, aluminum oxide, and manganese nitrate are weighed so as to have a predetermined composition, and these are mixed and then calcined, It was crushed and formed into a disk shape. Then, it was fired in the atmosphere at a maximum temperature of 1380 ° C. to obtain a disk-shaped positive temperature coefficient thermistor porcelain having a diameter of 14 g and a thickness of 2.5 g. Electrodes were provided on this by aluminum spraying, and the resistance value and its variation and the temperature coefficient of resistance were measured.

Further, as a conventional example, a sample in which TiNb ₂₄ O ₆₂ was not used was prepared and the same measurement as this example was performed.

The resistance values of the samples of the present example and the conventional example, their variations, and the measurement results of the temperature coefficient of resistance are shown in Table 1 below.
Shown in

[0013]

[Table 1]

In (Table 1), x is the x value in the above composition formula (Formula 1), the resistance value is the average value of 20 resistance values for each sample, and the dispersion is the standard deviation and average value of the resistance values. It is shown by the coefficient of variation, which is the ratio with. Further, sample numbers 1 to 7 are according to the present invention, and 8 is a conventional example.

As is clear from this (Table 1), the positive temperature coefficient thermistor porcelain according to the present embodiment has excellent characteristics that the variation in resistance value is small and the temperature coefficient of resistance is large.

[0016]

As described above, according to the present invention, in the method of manufacturing a positive temperature coefficient thermistor containing barium titanate as a main component and niobium as a semiconductor element, Ti is used as a raw material of niobium.
By using Nb ₂₄ O ₆₂ , it is possible to obtain an excellent positive temperature coefficient thermistor with a small resistance value variation and a large resistance temperature coefficient.

Claims (1)

[Claims] 1. A method for producing a positive temperature coefficient thermistor containing barium titanate as a main component, wherein when niobium is added as a semiconductor-forming element, TiNb ₂₄ O is used as a raw material for niobium.
_A method for manufacturing a positive temperature coefficient thermistor, which is characterized by using ₆₂ .