JPH0653009A - Multilayered thermistor - Google Patents

Abstract

PURPOSE:To reduce the resistance of a multilayered thermistor, and restrain the irregularity of the resistance value, by arranging inner electrodes for lowering the resistance between the first outer electrode and the second outer electrode. CONSTITUTION:A first and a second outer electrodes 12 and 13 are arranged on a thermistor resistor 11. In order to lower the resistance between the first and the second outer electrodes 12 and 13, inner electrodes 14 are arranged in the resistor 11, so as not to come into contact with the outer electrodes 12, 13 but to keep intervals L1, L2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to temperature compensation of electronic equipment,
The present invention relates to a laminated thermistor for use in current control, temperature detection, etc.

[0002]

2. Description of the Related Art A typical thermistor comprises a prismatic or plate-shaped thermistor resistor and a pair of electrodes formed at both ends by a dipping method or the like. This type of thermistor has an advantage that it can be manufactured at low cost due to its simple structure, but it has a drawback that the resistance value varies because it makes it difficult to set the mutual distance between the pair of electrodes to a predetermined value. . Further, it is difficult for this thermistor to secure a predetermined breakdown voltage and obtain a low resistance value.

In order to solve the above problems, FIG.
As shown in FIG.
It is described, for example, in Japanese Examined Patent Publication No. 50-11585, that the internal electrodes 2 and 3 are arranged and connected to the first and second external electrodes 4 and 5 to form a laminated structure.

[0004]

However, in the case of the laminated structure shown in FIG. 6, a connection failure occurs between the internal electrodes 2 and 3 and the external electrodes 4 and 5, and a desired resistance value cannot be obtained. Sometimes. In addition, since the internal electrodes 2 and 3 have a different thermal expansion coefficient from the thermistor resistor, when a heat cycle is applied to the thermistor, cracks occur in the internal electrodes 2 and 3 and the resistor 1, resulting in poor adhesion to each other and the internal electrode 2. 3 and the external electrodes 4, 5 may be defectively connected.

Therefore, an object of the present invention is to provide a laminated type thermistor which does not cause a problem of connection failure between the internal electrode and the external electrode and which can reduce the resistance.

[0006]

In order to achieve the above object, the present invention provides a thermistor resistor made of a resistance material whose resistance value changes in accordance with a temperature change, and a first thermistor resistor provided on the outer peripheral surface of the resistor. The first and second external electrodes are embedded in the resistor so as not to be connected to the first and second external electrodes, and are shorter than the mutual interval with respect to the first and second external electrodes. The present invention relates to a laminated thermistor including internal electrodes that are spaced apart from each other.

[0007]

In the present invention, the space between the first and second external electrodes and the internal electrode is used as the thermistor resistance. The internal electrode has a function of reducing the resistance between the first and second external electrodes. Since the internal electrode is not connected to the external electrode, the problem of poor connection to the external electrode does not occur at all. Further, since the internal electrodes are embedded in the resistor, it is possible to suppress the occurrence of cracks in the internal electrodes due to heat cycles.

[0008]

EXAMPLE A laminated NTC thermistor according to an example of the present invention will now be described with reference to FIGS. The thermistor shown in FIG. 1 has a resistor 11 made of an NTC thermistor material, first and second external electrodes 12 and 13, and a plurality of internal electrodes 14. The internal electrode 14 is composed of Ag-Pd conductor layers formed in a pattern shown in FIG. 3 on a plurality of virtual planes parallel to the upper surface of the rectangular parallelepiped-shaped resistor 11, and one end of the internal electrode 14 is distanced from the first external electrode 12. The second end is separated from the second external electrode 13 by a distance L2 which is substantially the same as L1. Therefore, the internal electrode 1
4 and the problem of poor connection between the first and second external electrodes 12 and 13 does not occur at all. The distances L1 and L2 are smaller than the mutual distance L3 between the first and second outer electrodes 12 and 13.
Therefore, the withstand voltage between the first and second external electrodes 12 and 13 is sufficiently secured. The first and second external electrodes 12 and 13 are formed on the pair of side surfaces of the resistor 11 and extend to the upper surface and the lower side of the resistor 11.

Next, a method of manufacturing the thermistor will be described with reference to FIG. First, a valence control agent and a sintering aid are added to a predetermined amount of manganese oxide and cobalt oxide, stirred in a wet ball mill, dehydrated and dried, calcined, and again stirred in a wet ball mill and dehydrated. Then, the powder was dried to obtain a powder of ceramic / NTC thermistor material.
Next, a predetermined amount of a polyvinyl butyral-based organic binder, a plasticizer, and a toluene-based solvent were added to this powder, and the mixture was stirred with a wet ball mill to remove the cells to obtain a slurry. Next, using this slurry, a thickness of 100 is obtained by the doctor blade method.
A plurality of μm green sheets (unfired ceramic sheets) were formed. As shown in FIG. 5, the green sheet 11a
11d are formed in a large area so that a large number of thermistors can be obtained from one sheet. Next, the conductor layers 14a for obtaining the internal electrodes 14 were formed on the first to third green sheets 11a to 11c by screen printing of Ag-Pd paste. Next, the first, second, third and fourth
4. The green sheets 11a, 11b, 11c and 11d are laminated in the order shown in FIG. 4, pressure-bonded, and then the position shown by the broken line in FIG. 4 is cut to obtain a thermistor molded body, and a molded body for debinding. Was heated in the air at 400 ° C. for 2 hours, and then fired in the air at 1200 ° C. for 2 hours to obtain a resistor 11 shown in FIGS. Finally, resistor 1
The first and second external electrodes 12 and 13 were formed by applying Ag—Pd paste on both side surfaces of No. 1 and baking.

FIG. 5 shows an equivalent circuit of the thermistor shown in FIG. The terminals 12a and 13a of FIG. 5 correspond to the first and second outer electrodes 12 and 13 of FIG. 1, and the resistors R1, R2 and R3 are between the left ends of the three inner electrodes 14 and the first outer electrode 12. And the resistances R4, R5, and R6 represent resistances between the right ends of the three internal electrodes 14 and the second external electrode 13.
Left resistors R1, R2, R3 and right resistors R4, R5,
An internal electrode 14 is provided between R6 and each other. If there is no inner electrode 14, the first and second outer electrodes 12, 13
The resistance value is determined depending on the mutual distance L3 between the two electrodes. However, when the internal electrode 14 is provided as in the present embodiment, it is equivalent to reducing the mutual distance L3 between the first and second external electrodes 12 and 13 by the internal electrode 14. And the resistance value becomes smaller. Further, since the plurality of internal electrodes 14 are provided, a resistance parallel connection circuit is formed, and the resistance value between the pair of external electrodes 12 and 13 is further reduced.

Since the internal electrode 14 is formed by screen printing as shown in FIG. 4, the error in the resistance value is small.
Further, since the portions of the green sheets 11a to 11d where the conductor layer 14a for the internal electrodes 14 is not provided are pressure-bonded to each other, it is possible to obtain a relatively stable laminated body with less peeling phenomenon.

[0012]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible. (1) In FIG. 1, L1 and L2 can have different values. (2) Without forming the first and second outer electrodes 12 and 13 after firing, the conductor paste can be applied to the molded body before firing to simultaneously form the inner electrodes and the outer electrodes. Alternatively, the first and second external electrodes 12 and 13 can be formed by a plating method, a dipping method, or the like.

[Brief description of drawings]

FIG. 1 is a central longitudinal sectional view showing a laminated thermistor according to an embodiment of the present invention.

FIG. 2 is a perspective view of the thermistor of FIG.

3 is a plan view showing a pattern of internal electrodes of FIG. 1. FIG.

FIG. 4 is a diagram showing a method of manufacturing the thermistor of FIG.

5 is an equivalent circuit diagram of the thermistor of FIG.

FIG. 6 is a sectional view showing a conventional laminated type thermistor.

[Explanation of symbols]

 11 Resistor 12 First External Electrode 13 Second External Electrode 14 Internal Electrode

Claims (1)

[Claims] 1. A thermistor resistor made of a resistance material whose resistance value changes in accordance with a temperature change, first and second external electrodes provided on an outer peripheral surface of the resistor, and the first and second And an internal electrode embedded in the resistor so as not to be connected to the external electrode and spaced from the first and second external electrodes by a distance shorter than the mutual distance therebetween. Type thermistor.