JPH07297008A - Positive temperature coefficient thermistor and thermistor device using the same - Google Patents

Abstract

PURPOSE:To provide a high reliable positive temperature coefficient thermistor capable of avoiding silver migration even under high temperature and humidity environment. CONSTITUTION:The first characteristics of the positive temperature coefficient thermistor is to provide on both main surfaces thereof with the first electrode layers 2a, 2b, 3a, 3b including silver layers formed so that the ends may come inside the periphery of the thermistor base material 1 as well as the second electrode layers 4a, 4b comprising aluminum formed as if covering the surface and sides of the first electrode layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive temperature coefficient thermistor and a thermistor device using the same, and more particularly to the structure of its electrode.

[0002]

2. Description of the Related Art Y, Nd, etc. are added to BaTiO ₃ in an amount of 0.1-0.1%.
The oxide semiconductor added with 0.3 at% has a large positive temperature coefficient, and is therefore called a PTC thermistor.

Since this PTC thermistor can adjust the temperature range having a large positive temperature coefficient by adding Sr, Pb, etc., it can be used for temperature measurement and overcurrent prevention, motor startup, color TV degaussing, etc. It has become an essential element in a wide variety of fields such as circuit elements and low-temperature heating heaters.

An example of such a thermistor is shown in FIG.
As shown in FIG. 3 (a), a thermistor body 11 formed by sintering oxides, carbonates, nitrates, chlorides, etc. of metals such as Ba, Ti, Nd, etc. into a thin columnar shape, and It is composed of first electrode layers 12a and 12b made of Ni plating layers formed on the upper and lower surfaces, and second electrode layers 13a and 13b having silver as a main component formed thereon.

By the way, such a positive temperature coefficient thermistor is
Normally, a voltage is applied between the second electrode layers 13a and 13b for use, but at this time, a so-called migration phenomenon occurs in which silver in the second electrode layer moves and precipitates in the direction of the electric field. In particular, when the outer peripheral edge of the second electrode layer is formed so as to reach the outer peripheral edge of the positive temperature coefficient thermistor element body 1, silver moves and precipitates in the direction of the electric field on the outer peripheral surface of the positive temperature coefficient thermistor element body 1. Finally, there was a problem of causing a short circuit.

Therefore, in order to solve this problem, FIG.
As shown in (b), a positive temperature coefficient thermistor has been proposed in which the outer diameter of the second electrode layer is smaller than the outer diameter of the first electrode layer. However, in this structure, since the outer shape of the second electrode layer is smaller than the outer shape of the first electrode layer, the portion of the first electrode layer that is not covered by the second electrode layer is directly Since it is exposed to the air, it is easily oxidized and the contact resistance gradually increases.

Further, since silver migration is a phenomenon of moving along the direction of the electric field, even if only the second electrode layer is provided inside the outer periphery as in the conventional example, the silver in the second electrode layer is exposed. As a result, although a slight amount of migration occurred, the problem of short circuit was mitigated but could not be completely prevented.

Further, in the conventional PTC thermistor, the electrodes are formed by using the plating method.
The characteristics of the sintered body may change, such as the plating solution permeating into the inside of the sintered body when Ni plating is performed during electrode formation, and the resistance value decreases. This may appear as a property change immediately after formation, or may gradually appear with time. As mentioned above, the thermistor is used for temperature measurement and control, compensation, gain adjustment, power measurement, overcurrent prevention, motor startup, color TV degaussing, etc., all of which require highly accurate resistance control. And
It is necessary to use those within the range of R ± α%. Therefore, the problem of resistance value change due to permeation of the plating solution is becoming more serious.

In order to avoid such penetration of the plating solution, a method of forming a low melting point metal such as aluminum by a metal spraying method and using this as an electrode has also been proposed. However, this method also cannot avoid the problem that a crack is generated in the thermistor element body or the electrode itself, because the temperature changes rapidly when the electrode is formed. Therefore, in order to solve this problem, the inventors of the present invention disclosed in Japanese Patent Laid-Open No. 6-
No. 5403 proposes a thermistor electrode structure using a printed electrode or a vapor deposition film containing aluminum as a main component. According to this structure, since aluminum is the main component, migration is completely eliminated. Further, since the printed or vapor-deposited film is used, the element body is not cracked and the durability is improved. However, since the first electrode is made of aluminum or the like, the resistance of the electrode itself increases, which is not suitable for a circuit in which a relatively large current flows.

Further, a nickel electrode is formed as a first electrode on both main surfaces of the thermistor element body, and a second electrode containing silver as a main component is formed around the nickel electrode, leaving a gap region around the nickel electrode. An electrode structure has also been proposed in which a third electrode made of aluminum-silicon is formed so as to cover the region to prevent migration (Japanese Patent Laid-Open No. 5-109503). However, this structure has a problem that the residual current is large because unevenness is formed on the surface and sufficient thermal contact cannot be obtained when two elements are used in a stacked manner.

Further, there has been proposed a method of heating the positive temperature coefficient thermistor for coils with a positive temperature coefficient thermistor for heaters in order to reduce the residual current. The heat contact deteriorates,
There is a problem that the residual current cannot be reduced.

[0012]

As described above, the conventional electrode structure has a problem that the contact resistance increases when aluminum is used to avoid migration and silver is used to prevent migration.

Further, in a structure in which an electrode containing silver as a main component is formed while leaving a gap region at the outer edge and the gap region is covered with an electrode made of aluminum-silicon, there is a portion where silver is exposed. There is a problem that the prevention of migration is insufficient, and that unevenness is formed on the surface and sufficient thermal contact cannot be obtained when two elements are used in a stacked manner, so that the residual current is large.

The present invention has been made in view of the above circumstances, and is a positive temperature coefficient thermistor suitable for a large current circuit, which has good assembling workability, is stable, has high reliability, and can completely prevent migration. The purpose is to provide.

[0015]

Therefore, a first feature of the present invention is that the positive characteristic thermistor element body is formed on both main surfaces so that the ends are located inside the outer peripheral edge of the positive characteristic thermistor element body. A first electrode layer including a formed silver layer, and a second electrode layer including a layer containing aluminum as a main component formed so as to cover the surface and the side surface of the first electrode layer. is there.

Preferably, the second electrode layer is 5-60.
It is composed of a thick film printing layer containing vol% conductive boron compound ceramics and aluminum. The conductive boron compound used here is not only TiB _{2 but also} ZrB.
₂ , HfB ₂ , VbB ₂ , TaB ₂ , CrB ₂ , MoB
2 borides, such as _{2, TiB, ZrB, HfB,} VBN
bB, TaB, CrB, MoB, WB, NiB mono-element boride or V ₃ B ₄ , V ₃ B ₂ , Nb ₂ B ₃ , Nb _{3
B 4, Ta 3 B 2,} Ta 3 B 2, Cr 3 B 4, Mo 3 B
₂ , at least one selected from the group of Mo ₂ B ₅ , W ₂ B ₅ , Ni ₄ B ₃ , and B ₄ C compounds, or compounds thereof.

A second feature of the present invention is that both ends of the positive temperature coefficient thermistor element body are formed so that their ends are inside the outer peripheral edge of the positive temperature coefficient thermistor element body, and the single layer including a silver layer. A plurality of layers of the first electrode layer, and a second electrode layer formed of a layer whose main component is aluminum and which is formed so as to cover the side surface from the vicinity of the edge of the first electrode layer. Especially.

A third feature of the present invention is that the positive characteristic thermistor element body is formed on both main surfaces so that the ends are located inside the outer peripheral edge of the positive characteristic thermistor element body, and includes a silver layer. Layer or a plurality of layers of the first electrode layer, a second electrode layer containing silver as a main component formed so as to cover the surface and the side surface of the first electrode layer, and an end of the second electrode layer. An aluminum layer formed to cover the side surface from the vicinity of the edge, or
The third electrode layer is composed of a layer containing 5 to 60 vol% of a conductive boron compound and aluminum.

A fourth feature of the present invention is that the first electrode layer formed on both main surfaces of the positive temperature coefficient thermistor body and the edge are located inside the edge of the first electrode layer. It is provided with the second electrode layer formed of the formed silver layer and the third electrode layer formed of the aluminum layer formed so as to cover the second electrode layer.

A fifth feature of the present invention is that a positive temperature coefficient thermistor formed on both main surfaces of the thermistor element body and having an outermost layer made of an aluminum layer and a terminal sandwiching the positive temperature coefficient thermistor. At least the region of this terminal that is in contact with the positive temperature coefficient thermistor is made of a substance that does not form an alloy with a melting point of 300 ° C. or lower with respect to aluminum.

Preferably this material is nickel, silver,
It is characterized by being any one of copper, aluminum, and titanium, or an alloy thereof.

[0022]

According to the above construction, since the silver electrode having good electric conductivity is used and the silver electrode is completely covered with the aluminum electrode, there is no possibility of short circuit due to migration.

In the above structure, the electrodes are formed by a dry process such as a vapor deposition method or a thick film printing method. Therefore, it is possible to form an electrode having a high adhesiveness and a low contact resistance without causing a characteristic change due to contamination of the exposed portion of the front surface and the back surface of the thermistor element body by a solution or the like when forming the electrode.

According to the first configuration, the first electrode layer including the silver layer is formed so that the end portion is located inside the outer peripheral edge of the positive temperature coefficient thermistor body, and the first electrode layer is formed. Since the second electrode layer made of the aluminum layer is formed so as to cover the surface and the side surface of the electrode layer, good electrical conductivity can be maintained and migration can be completely prevented. Desirably, the second electrode layer is 5-6
If a thick film printed layer containing 0 vol% of a conductive boron compound and aluminum is used, the conductivity does not decrease even if oxygen is trapped during the firing process of the electrode. Good electrical contactability can be maintained even in the region where the electrode layer contacts.

According to the second structure of the present invention, since the contact can be formed on most of the surface of the thermistor element body, the contact resistance can be further reduced. Further, since the edge portions of the first and second electrode layers are covered with the third electrode layer, cracks and cracks in the thermistor element body are further reduced.

According to the third structure of the present invention, the third electrode layer is formed so as to cover the edge and the side surface excluding a part of the entire surface of the second electrode layer, and the first structure. same as,
The contact resistance is reduced and good electrical contact can be maintained.

According to the fourth structure of the present invention, the entire surface of the thermistor element body is covered with the first electrode layer, and the second layer is formed on the first electrode layer.
Since the electrode layer of is formed, similar to the first configuration,
The occurrence of cracks and cracks in the thermistor body is further reduced.

According to the fifth aspect of the present invention, at the point where the terminal and the electrode come into contact with each other, that is, at the contact, heat is generated by a large current each time the voltage is turned on, so that the temperature locally rises and the temperature rises to 200. Although the temperature rises to some extent, at least the surface of the region of the terminal that comes into contact with the positive temperature coefficient thermistor is made of a material that does not form an alloy with aluminum at 300 ° C. or less, so that it can be maintained well without peeling. Desirably, the elastic terminal uses nickel, silver, copper, aluminum, titanium, or one of those alloys, which is a substance having a high melting point with an alloy with aluminum, or an alloy thereof for the surface layer.

[0029]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a diagram showing a positive temperature coefficient thermistor according to a first embodiment of the present invention.

This positive temperature coefficient thermistor comprises a thermistor element body 1 containing barium titanate as a main component, and silver formed by a printing method on the upper and lower surfaces of the thermistor body 1 so that the edges are located slightly inward from the outer peripheral edge. First electrode layers 2a and 2b made of a zinc (Ag-Zn) layer and the first electrode layers 2a and 2b
And second electrode layers 3a and 3b made of a silver layer (Ag) formed by a printing method so as to cover the second electrode layers 3a and 3
Third electrode layer 4 made of an aluminum-titanium boride (Al-TiB ₂ ) layer formed by a printing method so as to cover b.
It is composed of a and 4b. The thickness of each electrode layer is about 1
It was set to 0 μm. Next, the manufacturing process of this positive temperature coefficient thermistor will be described.

2 (a) and 2 (b) are process drawings showing the manufacturing process of the thermistor of the embodiment of the present invention.

First, as shown in FIG. 2 (a), TiO ₂ ,
Mix powders of BaCO ₃ and Nd ₂ O _{3 at} a predetermined ratio,
After calcination in the temperature range of 700 ° C to 1000 ° C, crushed, pressure-molded into a disk shape by the cold pressing method, and then sintered at 1300 ° C, a disk-shaped thermistor body having a diameter of 4.47 mm. 1 is formed.

Subsequently, as shown in FIG. 2B, the first to third electrode layers are sequentially applied to the end surface (electrode formation surface) of the thermistor element body 1 by the screen printing method. First, screen printing was performed using Ag-Zn paste, and 1
After the drying process at 80 ° C for 10 minutes, the Ag paste is used for screen printing, 180 ° C for 10 minutes, and finally the Al-TiB ₂ paste is used for the screen printing, and 180 ° C for 10 minutes. After that, it is formed through a firing process at 550 ° C. for 10 minutes.

Here, the Al-TiB ₂ paste is composed of aluminum powder having an average particle size of about 5 μm and Ti having an average particle size of 3 μm.
B ₂ and the ceramic powder 7 were mixed at a mixing ratio of 3, mixed with a binder, after a paste is obtained by adjusting the viscosity.

In the thermistor thus obtained, the electrode layer whose main component is Al that is not ionized in dew condensation water is Ag.
Since the electrode layer containing is completely covered, reliability can be maintained without migration of silver even when used for a long time in a high temperature and high humidity environment. And the electrical contact between the thermistor element and the electrode is good.

Since aluminum does not cause migration, electrodes can be applied to the entire main plane of the device. Therefore, the flow of rush current to the element becomes uniform, and the surge current or voltage when applying voltage is higher than before.
It is hard to get cracked.

Embodiment 2 FIG. 3 is a diagram showing a positive temperature coefficient thermistor according to a second embodiment of the present invention.

This positive temperature coefficient thermistor is a thermistor element body 1 containing barium titanate as a main component and a film thickness of 0.
From the first electrode layers 2m and 2m 'composed of a nickel (Ni) layer having a thickness of 3 to 2 μm, and the silver layer (Ag) formed by the screen printing method so that the edge comes slightly inward from the outer peripheral edge. Second electrode layers 3a, 3b and a third electrode layer 4a made of an aluminum-titanium boride (Al-TiB ₂ ) layer formed by a printing method so as to cover the second electrode layers 3a, 3b, 4b and. The film thickness of each of the second and third electrode layers was set to about 10 μm.

The formation is performed in the same manner as in the first embodiment.

The thermistor thus obtained also exhibits the above-mentioned effects as in the first embodiment.

For comparison, the thermistor element bodies 1 similar to those used in the first and second embodiments of the present invention were sequentially laminated by the printing method so that the edges were located slightly inward from the outer edges. A first electrode layer 2a composed of a silver-zinc layer,
An electrode structure having b and the second electrode layers 3a and 3b made of a silver layer was formed as Comparative Example 1 (FIG. 4).

Also, as Comparative Example 2, the third electrode layer of the thermistor of Example 2 was omitted, and the others were formed in the same manner.
(Fig. 5).

Next, in order to perform a migration test,
Using a test apparatus as shown in the explanatory diagram of FIG.
It was turned on for 30 minutes, turned off for 30 minutes, and applied for 1000 cycles. After the test, the side surface of the device was analyzed by EPMA to detect silver migration. The results are shown in a table in FIG. As is clear from this table, no migration was observed in the structures of Examples 1 and 2 of the present invention, whereas silver was slightly detected on the side surface in Comparative Examples 1 and 2.

Next, as shown in FIG.
Using the test equipment as shown in Fig.
At 0 ° C, turn on the voltage of 250V for 1 minute, turn off for 5 minutes, and
After application for 00 cycles, the cracking of the device after the test, the presence or absence of chipping, and the rate of change of resistance were measured. The results are tabulated in FIG. As is clear from this table, none of the examples showed any evidence of resistance, the rate of change in resistance was about -2.6 to -1.9%, and all were rated as "good".

Next, as shown in FIG.
0 using the test equipment as shown in Fig.
FIG. 11 shows the results of examining the presence or absence of cracking of the device after the test by applying the voltage at 20 ° C. while sequentially increasing the voltage from 250 V to every 50 V. As can be seen from this result, after the test was completed, the element was free from cracks.

Next, the thermistor of the first embodiment is shown in FIG.
A low temperature intermittent load test was performed to measure the terminal material. If the surface material of the terminal is composed of nickel or silver plating layer
As shown in the table of No. 3, there was no peeling of the electrode after the test. However, when the terminal was formed of solder or tin, peeling occurred at the terminal contact portion. Here, peeling means that peeling R occurs on the electrode surface corresponding to the contact portion with the terminal 10 as shown in FIG. In the low temperature intermittent load test, it is considered that aluminum and tin or solder are alloyed due to local temperature rise due to heat generation due to large current flowing each time voltage is applied. From these results, it can be seen that it is desirable to use nickel or silver that does not alloy with aluminum as the material used for the terminal surface.

The melting points of alloys of aluminum with nickel, silver and tin are shown in the table of FIG. 16 to 18
3 shows a relationship between the composition and melting point of the aluminum-tin alloy, a relationship between the composition and melting point of the silver-aluminum alloy, and a relationship between the composition of aluminum-nickel and the melting point.

By the way, at the contact, heat is generated by a large current each time the voltage is turned on, so that the temperature locally rises to about 200.degree. C.
It is desirable to use a material that does not form an alloy with aluminum below 300 ° C. As for the structure of the terminal, as shown in FIG. 19, the whole surface plating method in which the entire surface of the elastic terminal or the central terminal is composed of a plating layer of nickel, copper, silver, aluminum or the like, and only the contact area with the positive temperature coefficient thermistor are described above. There is a partial plating method in which a plating layer made of such a metal is used. In addition, it is possible to use a commonly used terminal made of tin and further provide a layer that does not alloy with tin on at least a portion of the aluminum electrode layer that is in contact with the terminal.

Next, in the first and second embodiments,
An example of adding TiB ₂ to Al has been described.
By changing the amount of B ₂ added, the relationship between the element resistance and the maximum surge voltage, which does not cause a crack, was measured. The results are shown in the table in FIG.

As is clear from this result, the addition amount is 5 vo
When the content is l% or more, the effect is exhibited, but when it is 70 vol% or more, firing becomes difficult. This is considered to be because the addition of TiB ₂ improves the ohmic contact between the thermistor element body and aluminum, so that the maximum surge voltage is improved. In the structure shown in Example 2, since the ohmic contact with the thermistor element was obtained by the nickel electrode, the addition of TiB ₂ had almost no effect on the maximum surge voltage.

From these comparisons as well, according to the present invention, a thermistor having stable specific resistance and high reliability can be obtained.

Next, a third embodiment of the present invention will be described. As shown in FIG. 21, this positive temperature coefficient thermistor comprises a thermistor element body 1 containing barium titanate as a main component, and a printing method sequentially applied to the upper surface and the lower surface of the thermistor element body 1 so that the edges are located slightly inward from the outer peripheral edge. Silver-zinc (Ag-
Zn) first electrode layers 2a, 2b and a silver layer (A
g) second electrode layers 3a, 3b, and aluminum-borides formed by a printing method so as to cover the side surfaces of the first and second electrode layers from the vicinity of the edge portions of the second electrode layers. Third electrode layer 4 made of a titanium (Al-TiB ₂ ) layer
It is composed of a and 4b. The thickness of each electrode layer is about 1
It was set to 0 μm.

According to this structure, since the first and second electrode layers are laminated in the same pattern shape, it is possible to bring both main surfaces of the PTC thermistor element body into contact with the first electrode layer more. Therefore, the contact resistance is reduced. In addition, since it is formed without covering the entire second electrode layer,
Since there are few materials, the cost can be reduced.

Next, a fourth embodiment of the present invention will be described. As shown in FIG. 22, this positive temperature coefficient thermistor has a thermistor element body 1 mainly composed of barium titanate and a top surface and a bottom surface so that the edges are located slightly intruded from the outer peripheral edge by a printing method. Formed silver-zinc (Ag-Z
n) first electrode layers 2a and 2b made of a layer, second electrode layers 3a and 3b made of a silver layer (Ag) formed by a printing method so as to cover the first electrode layer, and a second electrode layer edges of aluminum is formed by printing so as to cover the side surface from the vicinity of the electrode layer - the third electrode layer 4a made of titanium boride (Al-TiB ₂₎ layers, and a 4b. The film thickness of each electrode layer was about 10 μm. Also with this configuration, an inexpensive and highly reliable positive temperature coefficient thermistor can be obtained.

In the present invention, the aluminum layer means
It is not limited to pure aluminum, but refers to a layer containing aluminum as a main component.

[0057]

As described above, according to the present invention, it is possible to obtain a positive temperature coefficient thermistor which is easy to assemble and has stable characteristics without the risk of short circuit due to migration.

[Brief description of drawings]

FIG. 1 is a diagram showing a thermistor according to a first embodiment of the present invention.

[FIG. 2] Manufacturing process drawing of the thermistor

FIG. 3 is a diagram showing a thermistor according to a second embodiment of the present invention.

FIG. 4 is a view showing a conventional thermistor (comparative example).

FIG. 5 is a view showing a conventional thermistor (comparative example).

FIG. 6 is a diagram showing a test apparatus for a migration test.

FIG. 7 is a diagram showing the results of a migration test performed using the apparatus shown in FIG.

FIG. 8 is a diagram showing a test device for performing a low temperature intermittent load test.

9 is a diagram showing the results of a low temperature intermittent load test conducted using the apparatus shown in FIG.

FIG. 10 is a diagram showing a test device for performing a surge current test.

FIG. 11 is a diagram showing the results of a surge current test performed using the device shown in FIG.

FIG. 12 is a diagram showing a test device for measuring the dependency of a low temperature intermittent load test result on the terminal material.

13 is a diagram showing the results of a low temperature intermittent load test conducted using the apparatus shown in FIG.

14 is a diagram showing a state of peeling by a low temperature intermittent load test using the apparatus shown in FIG.

FIG. 15 is a diagram showing melting points of alloys of aluminum and nickel, silver, and tin.

FIG. 16 is a graph showing the relationship between the composition and melting point of an aluminum-tin alloy.

FIG. 17 is a diagram showing the relationship between the composition and the melting point of a silver-aluminum alloy.

FIG. 18 is a graph showing the relationship between aluminum-nickel composition and melting point.

FIG. 19 is a diagram showing an example of a terminal structure.

FIG. 20 is a diagram showing the results of measuring the relationship between element resistance and maximum surge voltage.

FIG. 21 is a diagram showing a thermistor according to a third embodiment of the present invention.

FIG. 22 is a diagram showing a thermistor according to a fourth embodiment of the present invention.

FIG. 23 is a diagram showing a conventional thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor body 2a, 2b 1st electrode layer 3a, 3b 2nd electrode layer 4a, 4b 3rd electrode layer 11 Thermistor body, 12a, 12b 1st electrode layer 13a, 13b 2nd electrode layer

Claims (7)

[Claims] 1. A positive temperature coefficient thermistor element body, and both main surfaces of the positive temperature coefficient thermistor element body are formed so that their ends are inside the outer peripheral edge of the positive temperature coefficient thermistor element body, and include a silver layer. A single layer or a plurality of layers of the first electrode layer; and a second electrode layer formed of a layer containing aluminum as a main component formed so as to cover the surface and the side surface of the first electrode layer. Characteristic PTC thermistor. 2. The second electrode layer comprises 5 to 60 vol%
The positive temperature coefficient thermistor according to claim 1, wherein the positive temperature coefficient thermistor is formed of a thick film printing layer containing the conductive boron compound and aluminum. 3. A positive temperature coefficient thermistor body, and both main surfaces of the positive temperature coefficient thermistor body are formed so that their ends are located inside the outer peripheral edge of the positive temperature coefficient thermistor body, and include a silver layer. A single layer or a plurality of layers of the first electrode layer, and a second electrode layer formed of a layer containing aluminum as a main component formed so as to cover the side surface from the vicinity of the edge portion of the first electrode layer. A positive temperature coefficient thermistor. 4. A positive temperature coefficient thermistor element body, and both main surfaces of the positive temperature coefficient thermistor element body are formed so that their ends are inside the outer peripheral edge of the positive temperature coefficient thermistor element body, and include a silver layer. A single layer or a plurality of layers of the first electrode layer, a second electrode layer containing silver as a main component formed so as to cover the surface and the side surface of the first electrode layer, and the second electrode layer Third layer composed of an aluminum layer formed so as to cover the side surface from the vicinity of the edge portion or a layer containing 5 to 60 vol% of a conductive boron compound and aluminum
A positive temperature coefficient thermistor. 5. A positive temperature coefficient thermistor element body, and a first member formed on both main surfaces of the positive temperature coefficient thermistor element body.
Electrode layer, a second electrode layer containing silver as a main component, the second electrode layer being formed so that its edge portion is located inside the edge of the first electrode layer, and the second electrode layer. A positive temperature coefficient thermistor, comprising: the aluminum layer formed in 1) or a third electrode layer comprising a layer containing 5 to 60 vol% of a conductive boron compound and aluminum. 6. A PTC thermistor body, and an outermost layer formed on both main surfaces of the PTC thermistor body, the outermost layer being an aluminum layer or a layer containing 5 to 60 vol% of a conductive boron compound and aluminum. Formed of a positive temperature coefficient thermistor and a terminal sandwiching the positive temperature coefficient thermistor, and at least a region of the terminal in contact with the positive temperature coefficient thermistor is a substance that does not form an alloy having a melting point of 300 ° C. or less with respect to aluminum. A thermistor device characterized by being configured. 7. The thermistor device according to claim 6, wherein the substance is any one of nickel, silver, copper, aluminum, titanium, or an alloy of two or more thereof.