JP2001028302A - Electrode for ptc thermistor, manufacture thereof, and ptc thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for a PTC thermistor which can have large bonding strength to conductive polymer and can be easily manufactured, a method for manufacturing the electrode, and a PTC thermistor. SOLUTION: An electrode includes a conductive substrate 11 and a sintered layer 12 formed on the substrate 11. The sintered layer 12 is a conductive sintered layer, which is formed by sintering conductive powder and has a uneven surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode for a PTC thermistor, a method for manufacturing the same, and a PTC thermistor.

[0002]

2. Description of the Related Art In recent years, overcurrent protection elements that can be used like return-type fuses have been actively used for protection of lithium batteries, protection of interfaces of electronic devices, and protection of charging circuits.

One of the overcurrent protection elements is a positive temperature coefficient (positive temperature coefficient).
thermistor (hereinafter, PT)
C thermistor) is known. The PTC thermistor includes a conductive polymer in which conductive particles are filled in a crystalline polymer, and a pair of electrodes disposed on both sides of the conductive polymer. When an overcurrent flows through the PTC thermistor, the temperature of the conductive polymer rises to near the melting point of the crystalline polymer due to self-heating, and the crystalline polymer expands in volume. And when the crystalline polymer expands rapidly near its melting point,
The conductive path of the conductive particles in the crystalline polymer is cut, the resistance between the electrodes increases, and the current flowing through the PTC thermistor is attenuated. Thus, the PTC thermistor
Overcurrent is attenuated.

[0004] In a PTC thermistor, if the adhesive force between the electrode and the conductive polymer is weak, the electrical resistance between the electrode and the conductive polymer increases when repeated overcurrent is applied, and the reliability decreases. Or it does not function as an element. Therefore, a strong adhesive force is required between the metal foil serving as an electrode and the conductive polymer.

As a method for increasing the adhesive force between a metal foil and a conductive polymer, a PTC thermistor using a metal foil having irregularities formed by electrodeposition has been reported (registered patent publication No. 2788968). The above patent publication discloses a method in which a metal foil is exposed to an electrolytic solution and a microrough surface is formed by electrodeposition.

[0006]

However, the above-mentioned conventional method of forming an uneven shape on a metal foil surface by electrodeposition has a problem that the adhesive force between the conductive polymer as a resin and the metal foil is not always sufficient. Was. Therefore, the conventional PTC thermistor has a problem that the rate of change in resistance increases when an overcurrent is repeatedly applied.

Further, since the electrodeposition process requires a long time,
There was a problem that the manufacturing cost was high. Further, there is a problem that it is difficult to control the plating solution during the electrodeposition process, and it is not possible to obtain a stable quality metal foil.

[0008] In order to solve the above-mentioned conventional problems, the present invention provides a P film which has a large adhesive force with a conductive polymer and is easy to manufacture.
Electrode for TC thermistor, method for manufacturing the same, and P
It is an object to provide a TC thermistor.

[0009]

In order to achieve the above object, an electrode for a PTC thermistor according to the present invention comprises a conductive substrate and a sintered layer formed on the substrate. Is a sintered layer having conductivity formed by sintering a conductive powder, and is a sintered layer having an uneven shape on the surface. The above PT of the present invention
According to the electrode for a C thermistor, an electrode for a PTC thermistor which has a large adhesive force with a conductive polymer and is easy to manufacture can be obtained.

In the above-mentioned electrode for a PTC thermistor according to the present invention, the center line average roughness Ra of the sintered layer is preferably 0.5 μm or more and 20 μm or less. According to the above configuration, it is possible to obtain an electrode for a PTC thermistor having a particularly large adhesive force with the conductive polymer.

In the above-mentioned electrode for a PTC thermistor of the present invention, the conductive powder has an average particle size of 0.1 μm or more and 50 μm or more.
m or less. According to the above configuration, it is possible to obtain an electrode for a PTC thermistor having a particularly large adhesive force with the conductive polymer.

In the PTC thermistor electrode of the present invention, it is preferable that a metal film is formed on the surface of the conductive powder. According to the above configuration, an electrode for a PTC thermistor in which a sintered layer can be easily formed can be obtained.

In the PTC thermistor electrode of the present invention, the base may be made of a metal material, and the metal film may be made of the same metal material as the base. According to the above configuration, since the diffusion speed of the sintering of the base and the conductive powder is equal, the joining between the base and the conductive powder by sintering proceeds in a short time, and the formation of a sintered layer is particularly easy for a PTC thermistor. An electrode is obtained.

In the electrode for a PTC thermistor according to the present invention, the base may be made of a metal material, and the metal film may be made of a metal material having a lower melting point than the base. According to the above configuration, since the conductive powder can be sintered at a low temperature, an electrode for a PTC thermistor in which formation of a sintered layer is particularly easy can be obtained.

In the above-mentioned electrode for a PTC thermistor according to the present invention, it is preferable that the conductive powder includes a powder in which a plurality of conductive particles are formed in a chain. According to the above configuration, since the volume of the voids occupying the sintered layer can be increased, an electrode for a PTC thermistor having particularly large adhesive force with the conductive polymer can be obtained.

In the above-mentioned electrode for a PTC thermistor according to the present invention, the conductive powder includes a conductive first powder and a conductive second powder, and the first powder has an average particle diameter. It is preferable that the average particle diameter of the second powder is twice or more. According to the above configuration, the first particle having a large particle size is used.
Since the second powder having a small particle size is arranged in the voids formed by the powders of the above, it is particularly easy to form the sintered layer.
An electrode for a C thermistor is obtained.

In the PTC thermistor electrode of the present invention, the content of the second powder contained in the conductive powder is preferably 60 wt% or less. According to the above configuration, since the adhesive force with the conductive polymer is ensured by the first powder having a large particle diameter, the PTC thermistor having sufficient adhesive force with the conductive polymer and particularly easy to form a sintered layer. Electrode is obtained.

The PTC thermistor electrode of the present invention preferably further comprises a metal film formed between the base and the sintered layer. According to the above configuration, it is possible to obtain a PTC thermistor electrode in which the base and the conductive powder can be easily sintered.

In the electrode for a PTC thermistor of the present invention, the metal film is made of nickel, copper, silver, gold, palladium, titanium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt and indium. It preferably contains at least one selected element. According to the above configuration, it is possible to obtain a PTC thermistor electrode in which sintering of the base and the conductive powder is particularly easy.

In the electrode for a PTC thermistor according to the present invention, it is preferable that the base has an uneven shape on the surface. According to the above configuration, an electrode for a PTC thermistor having a large adhesive force between the base and the sintered layer can be obtained.

In the electrode for a PTC thermistor of the present invention, the sintered layer includes a first sintered layer and a second sintered layer laminated from the substrate side, and the first sintered layer Is a sintered layer formed by sintering a conductive powder having an average particle size of 0.1 μm or more and 1 μm or less, and the second sintered layer is formed by sintering a conductive powder having an average particle size of 1 μm or more. It is preferable that the sintered layer is formed by bonding. According to the above configuration, the adhesive strength between the base and the sintered layer can be increased by the first sintered layer. Further, the PTC thermistor electrode having a large adhesive force between the sintered layer and the conductive polymer can be obtained by the second sintered layer.

In the electrode for a PTC thermistor according to the present invention, the conductive powder is iron, nickel, copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt, molybdenum. ,
It is preferable to use a metal material containing at least one element selected from tungsten, manganese, indium and titanium. According to the above configuration, since the conductive powder has good conductivity, the contact resistance with the conductive polymer can be reduced, and an electrode for a PTC thermistor having excellent electric conductivity can be obtained.

In the electrode for a PTC thermistor of the present invention, it is preferable that the base is made of a metal material containing at least one element selected from iron, copper and nickel. According to the above configuration, PT having particularly excellent electric conductivity is used.
An electrode for a C thermistor is obtained.

According to the method of manufacturing an electrode for a PTC thermistor of the present invention, a first step of applying a paste containing a conductive powder to the surface of a conductive substrate, and a step of heat-treating the paste to form the conductive powder And a second step of forming a sintered layer. According to the method for manufacturing an electrode for a PTC thermistor, the electrode for a PTC thermistor of the present invention can be easily manufactured. Furthermore, according to the method for manufacturing an electrode for a PTC thermistor, the particle size and shape of the conductive powder contained in the paste,
By changing the thickness or the like of the sintered layer, a sintered layer having various center line average roughnesses Ra can be easily formed.

In the method of manufacturing an electrode for a PTC thermistor, the conductive powder has an average particle size of 0.1 μm or more and 50 μm or more.
m or less. According to the above configuration, it is possible to manufacture an electrode for a PTC thermistor having a particularly large adhesive force with the conductive polymer.

Preferably, the method of manufacturing an electrode for a PTC thermistor further comprises a step of forming a metal film on the surface of the base before the first step. According to the above configuration, the sintering of the base and the conductive powder can be particularly easily performed.

[0027] The method of manufacturing an electrode for a PTC thermistor preferably further comprises, before the first step, a step of forming irregularities on the surface of the base. According to the above configuration, it is possible to manufacture a PTC thermistor electrode having a large adhesive force between the base and the sintered layer.

[0028] In the above method for producing an electrode for a PTC thermistor, the conductive powder has an average particle diameter of 0.1 µm or more and 1 µm or more.
m or less, and after the second step, the average particle size is 1 μm.
It is preferable to include a third step of forming a sintered layer laminated on the sintered layer by applying a paste containing a conductive powder of m or more to the sintered layer and then performing a heat treatment. According to the above configuration, a dense sintered layer and a sintered layer having many voids can be laminated from the substrate side, and a PTC thermistor electrode including a sintered layer having a large adhesive force between the substrate and the conductive polymer is provided. Can be manufactured.

In the above method of manufacturing an electrode for a PTC thermistor, it is preferable that the first step further includes a step of applying the paste and then drying and rolling the paste applied to the base. According to the above configuration, sintering of the base and the conductive powder can be easily performed.

In the above-mentioned method for producing an electrode for a PTC thermistor, the heat treatment is preferably performed in a reducing atmosphere. According to the above configuration, a sintered layer whose surface is not oxidized can be formed. By using a PTC thermistor electrode having such a sintered layer, a PTC thermistor having a particularly small rate of change in resistance value can be manufactured.

[0031] In the above method for manufacturing an electrode for a PTC thermistor, the conductive powder may be iron, nickel, copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt, indium. And a metal material containing at least one element selected from titanium.

In the method of manufacturing an electrode for a PTC thermistor, the base is preferably made of a metal material containing at least one element selected from iron, copper and nickel. According to the above configuration, an electrode for a PTC thermistor having excellent electric conductivity can be manufactured.

The PTC thermistor of the present invention is a PTC thermistor including at least one pair of electrodes and a conductive polymer disposed between the pair of electrodes (the PTC thermistor may include a plurality of pairs of electrodes). The present invention is characterized in that it is an electrode for a PTC thermistor of the present invention. According to the above configuration, since the adhesive force between the electrode and the conductive polymer is large, the resistance value change rate when the overcurrent is repeatedly applied is small.
A TC thermistor is obtained.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In Embodiment 1, an example of an electrode for a PTC thermistor of the present invention will be described. FIG. 1 schematically shows a partial cross-sectional view of the PTC thermistor electrode 10 according to the first embodiment.

Referring to FIG. 1, PTC thermistor electrode 10 includes a conductive base 11 and a sintered layer 12 formed on base 11 (hatching is omitted).

The base 11 is made of a conductive material, and is, for example, a foil (metal or alloy or a compound of a non-metal element and a metal element; the same applies hereinafter), a metal plate, a punching metal. , A conductive resin, a conductive ceramic, or the like can be used. Among them, the base 11 is preferably made of a metal material. Specifically, for the base 11, a metal material containing at least one element selected from copper, nickel and iron can be used. For example, the base 11 can be made of copper, nickel, iron, an alloy thereof, or a compound of these with a nonmetallic element. Among them, copper or copper alloy is particularly preferable.

The metal film 13 may be formed on the surface of the base 11 (between the base 11 and the sintered layer 12).
FIG. 2 shows an example of the PTC thermistor electrode 10a in this case. The metal film 13 is made of nickel, copper, silver,
It is preferable to include at least one element selected from gold, palladium, titanium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt and indium. For example, nickel, copper, nickel boron, nickel phosphorus, or the like can be used for the metal film 13. The thickness of the metal film 13 is preferably from 0.1 μm to 10 μm, and particularly preferably about 2 μm.

The substrate 11 may have an uneven shape 14 on its surface (in this case, the substrate 11 and particularly the substrate 11a). Regarding the PTC thermistor 10b in this case,
An example is shown in FIG. Note that the metal film 13 may be further formed on the uneven shape 14.

The sintered layer 12 is a sintered layer having conductivity formed by sintering a conductive powder, and is a sintered layer having an uneven shape on the surface. The sintered layer 12 is formed on at least one main surface of the base 11. Sintered layer 12
Is preferably 0.5 μm or more and 20 μm or less (the center line average roughness Ra will be described at the end of the first embodiment). In particular, the sintered layer 12
Is preferably 1 μm or more and 5 μm or less. As a result, an electrode for a PTC thermistor having particularly large adhesion to the conductive polymer can be obtained.

The conductive powder as the material of the sintered layer 12 includes:
Although a variety of particle sizes can be used, it is preferable to use a conductive powder having an average particle size of 0.1 μm or more and 50 μm or less.

Various materials having conductivity can be used for the conductive powder. For example, metal materials, conductive resins, conductive ceramics, and the like can be used. For example, the conductive powder includes iron, nickel,
Copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt,
A metal material containing at least one element selected from indium and titanium can be used. Specifically, for example, iron, nickel, copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead,
Chromium, platinum, tin, cobalt, indium, or titanium, or an alloy thereof, or a compound of any of these and a nonmetallic element can be used. Among them, nickel is particularly preferred.

The conductive powder contains a first powder having conductivity and a second powder having conductivity, and the average particle size of the first powder is the average particle size of the second powder. May be twice or more. At this time, it is preferable that the content of the second powder contained in the conductive powder is 60 wt% or less.

The conductive powder may have various shapes such as a true sphere, a needle, an ellipsoid or a chain. As the conductive powder, in particular, a powder having a value of (major axis) / (minor axis) of 1.3 or more, a powder having a value of (long side) / (short side) of 1.3 or more, A powder formed by forming a plurality of particles having conductivity in a chain shape is preferable. Thereby, the sintered layer 12 in which the ratio of the voids is large can be formed, and an electrode for a PTC thermistor having a particularly large adhesive force with the conductive polymer can be obtained.

The conductive powder may have a metal film formed on the surface. For example, the same metal material as the base 11 or the base 11
For example, a metal material having a lower melting point can be used.
The metal film can be formed by a plating method, an evaporation method, or the like.

Further, the sintered layer 12 may include two sintered layers. FIG. 4 shows an example of the PTC thermistor 10c in this case. Referring to FIG. 4, sintered layer 12 of PTC thermistor 10c includes a first sintered layer 12a and a second sintered layer 12b laminated from base 11 side. The first sintered layer 12a has an average particle size of 0.1 μm or more and 1 μm
It is a sintered layer (dense sintered layer) having conductivity formed by sintering the following conductive powder. Also, the second sintered layer 12
b is a conductive sintered layer formed by sintering a conductive powder having an average particle size of 1 μm or more. The sintered layer 12
It is particularly preferable that b is a sintered layer formed by sintering a conductive powder having an average particle size of 2.2 μm or more and 3.3 μm or less. As a result, when the PTC thermistor is formed, an electrode for a PTC thermistor having a particularly large adhesive force with the conductive polymer can be obtained.

In the PTC thermistor electrode 10 of the first embodiment, the sintered layer 12 is formed on the base 11 to form an uneven shape on the surface. Therefore, P
According to the TC thermistor electrode 10, when the PTC thermistor is formed, the adhesive force with the conductive polymer can be increased. In addition, the PTC thermistor electrode 10
Can be easily manufactured.

The method of measuring the center line average roughness Ra (JIS B-0601) will be described below. The center line average roughness Ra is a parameter representing the surface roughness. Specifically, the center line average roughness Ra is obtained by taking the x-axis in the direction of the average line and the y-axis in the vertical direction for a roughness curve extracted by the reference length L, and defining the roughness curve as y = f ( x), the value determined by the following equation is expressed in micrometers (μ
m) (see FIG. 5 which is a schematic diagram).

[0049]

(Equation 1)

The center line average roughness Ra can be measured using a commercially available measuring device (for example, Surfcom 5 manufactured by Tokyo Seimitsu Co., Ltd.).
50A) can be easily measured.

(Embodiment 2) In Embodiment 2, an example of a method for manufacturing a PTC thermistor electrode of the present invention will be described. In addition, about the part demonstrated in Embodiment 1,
A duplicate description will be omitted.

First, as shown in FIG.
Prepare At this time, the PTC thermistor electrode 10a
Is used, the substrate 11 having the metal film 13 formed on the surface is used. The metal film 13 can be formed by a plating method or a vapor deposition method. Also, the PTC thermistor electrode 10b
Is used, a substrate 11a having an uneven shape formed on the surface is used. The base 11a can be formed by subjecting the base 11 to a process such as a chemical etching process, an electrolytic etching process, a sand blast process, a press process, or a metallikon (metal spray coating method).

Thereafter, as shown in FIG. 6B, a paste 62 containing a conductive powder 61 (hatching is omitted).
Is applied to the surface of the substrate 11.

The paste 62 is obtained by adding the conductive powder (the material of the sintered layer 12) described in the first embodiment to a solvent in which a polymer compound (binder) is dissolved and kneading the mixture. As a solvent that is a material of the paste 62, an organic solvent such as butyl acetate, butyl cellosolve, butyl carbitol, α-terpineol, or an alcohol, or water can be used. Examples of the polymer compound (binder) that is a material of the paste 62 include cellulose resins such as methyl cellulose, ethyl cellulose, and nitrocellulose, polyvinyl alcohol resins, butyral resins,
Acrylic resin such as methyl methacrylate, polyacetal resin, rosin and the like can be used.

Specifically, first, a polymer compound of about 1 wt% to 15 wt% is added to a solvent, and then the polymer compound is dissolved by heating, and the vehicle (v
vehicle). Then, 50 parts by weight to 1
For 50 parts by weight of the vehicle, the conductive powder 100
The paste 62 is obtained by adding parts by weight and kneading well with a kneader. The paste 62 thus obtained is applied to the substrate 11. As a coating method, a doctor blade method, a dip coater method, a die coater method, a reverse roll coater method, a screen printing method, a bar coater method, or the like can be used.
In addition, the vehicle may contain a plasticizer, an antifoaming agent, a dispersant, and the like as necessary.

Thereafter, the substrate 1 on which the paste 62 was applied
1 is heat-treated in a neutral atmosphere or an oxidizing atmosphere to dry the paste 62 and to remove the binder. Examples of the neutral atmosphere gas include a nitrogen gas and a carbon dioxide gas. As an oxidizing atmosphere gas,
An example is air. Note that nitrogen gas to which steam is added is particularly preferable.

After applying the paste 62 and before removing the binder, a step of drying and rolling the paste 62 may be performed. Rolling can be performed using a press device such as a rolling roll, for example. At this time, for example, by performing rolling at a temperature of 40 ° C. or more, the adhesion between the conductive powder and the base 11 can be improved.

Thereafter, the paste 62 is fired to form the sintered layer 12 as shown in FIG. The firing is performed in a reducing atmosphere at 200 ° C. to 1200 ° C.
The heat treatment is carried out at a temperature of 0.5 ° C. for about 30 minutes. As the gas in the reducing atmosphere, for example,
Examples thereof include a hydrogen-nitrogen mixed gas, a hydrogen-carbon dioxide gas mixed gas, and a gas obtained by adding steam thereto. After the firing, the base 11 is cooled in a reducing atmosphere, if necessary. Thus, the PTC thermistor electrode 1
0 can be produced.

When manufacturing the PTC thermistor electrode 10c shown in FIG.
Paste 6 containing conductive powder having a size of not less than 1 μm and not more than 1 μm
2 is used to form a sintered layer 12a. Then, a paste containing a conductive powder having an average particle size of 1 μm or more is applied to the sintered layer 12.
a, and the sintered layer 12b may be formed by the same method as described in the step of FIG.

An example of the sintering apparatus used in the above manufacturing method is as follows.
FIG. 7 schematically shows this.

Referring to FIG. 7, the sintering apparatus includes a coater section 71, a binder removing section 72, a firing section 73, and a cooling section 7.
4 is provided.

The coater 71 is formed by adding the paste 6 to the base 11.
2 is a part to be applied.

The binder removal section 72 is a section for drying the paste 62 applied to the base 11 and removing the binder by performing a heat treatment at a temperature of about 400 ° C. The binder removal section 72 is preferably filled with a neutral atmosphere gas (such as nitrogen gas or carbon dioxide gas) or an oxidizing atmosphere gas (such as air). In particular, it is preferable that the gas is filled with nitrogen gas to which steam is added.
When the paste 62 is rolled, a pressing device such as a roll is used to form the coater 71 and the binder removing unit 72.
And placed between.

The firing part 73 is a part for forming the sintered layer 12 by performing a heat treatment at a temperature of about 200 ° C. to 1200 ° C. The firing section 73 is preferably filled with a reducing atmosphere gas (a mixed gas of hydrogen and nitrogen, a mixed gas of hydrogen and carbon dioxide, or a mixed gas obtained by adding steam to these gases).

The cooling section 74 is a section for cooling the substrate 11 on which the sintered layer 12 is formed at a temperature of, for example, 100 ° C. to 500 ° C. The cooling section 74 is preferably filled with a reducing atmosphere gas or a neutral atmosphere gas.

The substrate 11 on which the sintering layer 12 has been formed by the sintering apparatus is cut into a predetermined size, and
It becomes the TC thermistor electrode 10.

According to the manufacturing method of the second embodiment, the PTC thermistor electrodes 10 and 10 described in the first embodiment are used.
a, 10b and 10c can be easily manufactured. In particular, the center line average roughness of the sintered layer 12 can be easily controlled by changing the particle size or shape of the conductive powder 61 contained in the paste 62 or by changing the applied film thickness.

Embodiment 3 In Embodiment 3, an example of a PTC thermistor of the present invention will be described.

Referring to FIG. 8, a PTC thermistor 80 according to the third embodiment includes at least a pair of PTC thermistor electrodes 10 (including PTC thermistor electrodes 10a, 10b and 10c) and a pair of PTC thermistor electrodes 10. Conductive polymer 81 and solder 82
And a lead wire 83 connected to the PTC thermistor electrode 10.

The PTC thermistor electrode 10 is the PTC thermistor electrode described in the first embodiment or the PTC thermistor electrode manufactured by the manufacturing method of the second embodiment. The PTC thermistor electrode 10 has a sintered layer 12
Are arranged so as to be in contact with the conductive polymer 81.

The conductive polymer 81 is a conductive polymer having PTC characteristics. As the conductive polymer 81, for example, a crystalline polymer containing conductive particles can be used. The conductive particles in the conductive polymer 81 include, for example,
Carbon black can be used. The crystalline polymer that is the material of the conductive polymer 81 includes, for example,
HDPE (high density polyeth)
ylene), LDPE (low density p)
polyethylene), PP (polypropyly)
(lene) polypropylene, EVA (ethylene)
vinyl acetate copolymer)
Etc. can be used.

The PTC thermistor 80 according to the third embodiment
Since the PTC includes the PTC thermistor electrode 10 of the present invention, the adhesive force between the PTC thermistor electrode 10 and the conductive polymer 81 is large. For this reason, according to the PTC thermistor 80, a PTC thermistor with a small change in resistance value is obtained even when an overcurrent is repeatedly applied.

Note that the PTC thermistor of the present invention
What is necessary is just to provide the electrode 10 for C thermistors, and it is not limited to the structure shown in FIG. For example, in FIG.
Although the PTC thermistor including the pair of PTC thermistor electrodes 10 has been described, the PTC thermistor of the present invention may include two or more pairs of PTC thermistor electrodes. Also,
The PTC thermistor of the present invention may be a surface mount type or an axial type PTC thermistor, or may be a multilayer PTC thermistor having three or more PTC thermistor electrodes.

[0074]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrode for a PTC thermistor of the present invention will be described below.
A specific example of manufacturing a PTC thermistor using the same will be described.

(Example 1) 5% by weight of butyral resin,
2 wt% of dibutyl phthalate as a plasticizer, 45 wt% of butyl acetate as a solvent and 48 w of butyl cellosolve
and t% to obtain a vehicle (hereinafter, a vehicle having this mixing ratio is referred to as a vehicle A). This vehicle A100
1 parts by weight of nickel powder (conductive powder) with an average particle size of 4 μm
And 100 parts by weight to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method (application speed was 10 mm / sec, which is the same in the following examples) so as to have a film thickness of 30 μm. . Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, heat treatment is performed at 900 ° C. for 5 minutes in a mixed gas of 55% hydrogen and 45% nitrogen (% of the mixed gas represents a volume ratio; the same applies to the following description).
An electrode for a PTC thermistor was obtained by forming a sintered layer. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was measured using Surfcom 550A (manufactured by Tokyo Seimitsu Co., Ltd.) (cutoff value 0.8 mm, reference length 2.5 m).
m) was 5.5 μm. In addition, also in the following examples, the center line average roughness Ra of the sintered layer surface is
It measured by the same method.

Thereafter, a PTC thermistor was manufactured using the PTC thermistor electrode. Specifically, first,
HDPE (Mitsui Chemicals) 48, a kind of crystalline polymer
wt% and 52 wt% of carbon black (manufactured by Mitsubishi Chemical Corporation) were mixed using two heat rolls heated to 190 ° C., and then formed into a sheet having a thickness of 0.5 mm to obtain a conductive polymer sheet. Was. This conductive polymer sheet is sandwiched between the two PTC thermistor electrodes and thermocompression-bonded (150 ° C.,
490 N / cm ² (50 kgf / cm ² )) to obtain a laminate. Lead wires were attached to the copper foil on both sides of the laminate by soldering to obtain a PTC thermistor.

The PTC thermistor thus obtained was subjected to an overcurrent application cycle test. The overcurrent application cycle test was performed by repeating 1000 cycles of one-minute energization and five-minute interruption of energization as one cycle. At this time, energization was performed by connecting the PTC thermistor to a 12 V DC power supply and a load resistor so that an overcurrent of 40 A could be applied.

P before and after the overcurrent application cycle test
The resistance of the TC thermistor was measured, and the rate of change in resistance before and after the overcurrent application cycle test was calculated. Here, the resistance value change rate is a value represented by (resistance value after test−resistance value before test) / (resistance value before test) × 100 (%). Table 1 shows the average value of the values measured for the 10 PTC thermistors of Example 1 (in the following Examples and Comparative Examples, all the values shown in Table 1 are the average values of 10 PTC thermistors).

[0079]

[Table 1]

Further, with respect to the PTC thermistor of Example 1, the peel strength between the conductive polymer and the PTC thermistor electrode was measured (peel test). Example 1
Table 2 shows the average value of the values measured for the five PTC thermistors (in the following Examples and Comparative Examples, all the values shown in Table 2 are the average values of five PTC thermistors).

[0081]

[Table 2]

Example 2 100 g of an aqueous solution containing 3.5 wt% of methylcellulose and 90 g of silver powder (conductive powder) having an average particle size of 2 μm were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, in nitrogen gas or air, 45
The binder was removed by heat treatment at 0 ° C. Thereafter, a sintered layer was formed by performing a heat treatment at 870 ° C. for 5 minutes in a mixed gas (hydrogen 35% -nitrogen 65%) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintering layer thus formed is:
It was 2 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. That is, a conductive polymer sheet prepared under the same conditions as in Example 1 was sandwiched between the two PTC thermistor electrodes, and was heated at 150 ° C. and 490 N / cm ² (50 kgf / c).
m ² ), a laminate was obtained by thermocompression bonding, and lead wires were attached to metal foils on both sides of the laminate by soldering to obtain a PTC thermistor (similarly in the following examples). A PTC thermistor was made). And
Under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 3 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were kneaded well to obtain a paste. This paste is 60μ thick
m of nickel foil (substrate) was applied to a thickness of 100 μm by a doctor blade method. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a sintered layer was formed by performing a heat treatment at 900 ° C. for 5 minutes in a mixed gas (5% hydrogen-95% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 4 100 g of vehicle A and 100 g of chromium powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste has a thickness of 60 μm
Was applied by a doctor blade method to a film thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a sintered layer was formed by performing a heat treatment at 1000 ° C. for 5 minutes in a mixed gas (65% hydrogen-35% nitrogen) to obtain an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Note that, even when copper foil was used as the substrate, the same results as those of Example 4 shown in Tables 1 and 2 were obtained. As the conductive powder, gold powder, platinum powder, palladium powder, brass powder, bronze powder, cobalt powder, nickel silver powder, copper powder, nickel-plated copper powder, tin powder, zinc powder, tungsten powder, molybdenum powder, manganese powder , The same result as in Example 4 was obtained.

Example 5 100 g of vehicle A and 100 g of conductive powder (a mixture of 3 g of zinc powder having an average particle diameter of 0.3 μm and 97 g of copper powder having an average particle diameter of 2 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a nickel foil (substrate) having a thickness of 60 μm by a doctor blade method.
It was applied to a thickness of μm. Thereafter, the binder was removed by performing a heat treatment at 390 ° C. in a mixed gas (steam 10% -nitrogen 90%). Then, in a mixed gas (hydrogen 50% -nitrogen 50%),
A heat treatment was performed at 800 ° C. for 5 minutes to form a sintered layer, and an electrode for a PTC thermistor was obtained. The center line average roughness Ra of the surface of the sintered layer formed in this way is 2.
It was 5 μm. The same center line average roughness Ra was obtained even when a copper foil having a thickness of 60 μm was used as the substrate.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 6 80 g of vehicle A and 100 g of gold powder (conductive powder) having an average particle size of 3 μm were kneaded well.
A paste was obtained. This paste was applied to a nickel foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
m. Thereafter, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas or air. Then, the mixed gas (hydrogen 50%
(Nitrogen 50%) was subjected to a heat treatment at 980 ° C. for 5 minutes to form a sintered layer to obtain an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 2 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 7 100 g of vehicle A and 100 g of cobalt powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 60μ thick
m on a copper foil (substrate) by the doctor blade method.
It was applied to a thickness of μm. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, the mixed gas (hydrogen 25
% -Nitrogen 75%) at 900 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 4 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In Example 7, similar results were obtained when a copper foil or a nickel foil was used as the substrate. Further, in Example 7, sintering could be performed in a gas having a hydrogen gas content of 0.1% to 100% (the same applies to other examples). Further, by performing the binder removal in the nitrogen gas, the sintering time could be shortened as compared with the case where the binder removal was performed in the air. When the binder was removed in a gas obtained by adding water vapor to nitrogen gas, the sintering time could be further reduced.

Example 8 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 60μ thick
m of stainless steel (substrate made of SUS304) was applied to a thickness of 27 μm by a doctor blade method. Then, in nitrogen gas or air
The binder was removed by heat treatment at 50 ° C. Thereafter, a sintered layer was formed by performing a heat treatment at 900 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 9 A paste was obtained by thoroughly kneading 120 g of vehicle A and 100 g of conductive powder (a mixture of 80 g of nickel powder having an average particle diameter of 3 μm and 20 g of nickel powder having an average particle diameter of 1 μm or less). This paste has a thickness of 1
It was applied to a substrate (60 μm thick copper foil) plated with 0 μm nickel by a doctor blade method so as to have a thickness of 27 μm. Thereafter, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a sintered layer was formed by performing a heat treatment at 890 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 4 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Similar results were obtained when a chromium-plated copper foil was used as the substrate.

Example 10 120 g of vehicle A and 100 g of conductive powder (a mixture of 80 g of nickel powder having an average particle diameter of 3 μm and 20 g of nickel powder having an average particle diameter of 1 μm or less) were sufficiently kneaded to obtain a paste. This paste was applied to a 1.5 μm-thick nickel-plated substrate (60 μm-thick
Was applied by a doctor blade method to a film thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a sintered layer was formed by performing a heat treatment at 890 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

The thickness of the nickel plating is 0.01 μm.
Similar results were obtained with m.

Further, by setting the content of nickel powder having an average particle size of 0.7 μm or less to 60 wt% or less in the conductive powder, an electrode for a PTC thermistor having a strong bonding force with a conductive polymer can be obtained. Was.

Particularly preferable results were obtained by using a columnar powder or a rectangular parallelepiped powder as the conductive powder. Specifically, a PTC thermistor having a small rate of change in resistance was obtained by using elliptic particle powder having an oblateness of 2 or more and acicular particle powder having an acicular ratio of 1.3 or more. In particular, when a conductive powder having a structure in which a plurality of particles are connected in a chain is used, a PTC thermistor having a very small resistance value change rate was obtained. When these conductive powders are used, the voids in the sintered layer become large,
It is considered that the adhesive strength with the conductive polymer is improved.

Example 11 120 g of vehicle A and 100 g of conductive powder (a mixture of 80 g of copper powder having an average particle diameter of 3 μm and 20 g of nickel powder having an average particle diameter of 1 μm or less) were sufficiently kneaded to obtain a paste. This paste has a thickness of 60 μm
20μ by the doctor blade method on the copper foil (substrate)
m. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, the mixed gas (hydrogen 50
% -Nitrogen 50%) at 900 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 2 μm. The same center line average roughness Ra was obtained even when a nickel foil having a thickness of 100 μm or a nickel plate having a thickness of 1 mm was used as the substrate.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 12 120 g of vehicle A and 100 g of conductive powder (a mixture of 80 g of copper powder having an average particle diameter of 3 μm and 20 g of nickel powder having an average particle diameter of 2 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
Was applied so as to have a film thickness. Then, by heat treatment at 450 ° C. in nitrogen gas or air,
Binder removal was performed. Then, the mixed gas (hydrogen 50%-
A sintered layer was formed by performing a heat treatment at 900 ° C. for 5 minutes in nitrogen (50%) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

As the conductive powder, instead of copper powder and nickel powder, titanium powder, chromium powder, platinum powder, cobalt powder, silver powder, gold powder, brass powder, bronze powder, nickel silver powder, tungsten powder, molybdenum powder, Manganese powder, palladium powder,
Similar results were obtained using zinc powder, tin powder, and metal powder plated with nickel phosphorus or nickel boron.

(Example 13) 5 g of rosin and α as a solvent
The vehicle was obtained by mixing with 100 g of terpineol.
105 g of this vehicle and 100 g of conductive powder (90 g of copper powder having an average particle size of 3 μm and tin powder 10 having an average particle size of 1 μm or less)
g) to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, at 700 ° C. in a mixed gas (50% hydrogen—50% nitrogen) at 5 ° C.
A sintered layer is formed by heat treatment for
The thermistor electrode was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Good results were obtained when conductive powder having a tin powder content of 30 wt% or less (copper powder content of 70 wt% or more) was used as the conductive powder.

Further, gold, palladium, silver,
Similar results were obtained using metal foil plated with zinc, tin, iron, copper, nickel, cobalt, chromium, platinum, titanium, nickel silver, brass, bronze, nickel phosphorus or nickel boron. Further, when the same material was plated on the base and the conductive powder, the heat treatment time could be reduced.

Example 14 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were kneaded well to obtain a paste. This paste is 2μ thick
m was coated on a substrate (a copper foil having a thickness of 60 μm) plated with palladium to a thickness of 27 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a mixed gas (50% hydrogen-50 nitrogen)
%), A heat treatment was performed at 950 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 4.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 15 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
m was coated on a substrate (copper foil having a thickness of 60 μm) plated with indium to a thickness of 27 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a mixed gas (50% hydrogen-50 nitrogen)
%), A heat treatment was performed at 850 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 4 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 16 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
m tin-plated substrate (60 μm thick copper foil)
It was applied to a thickness of 27 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, a sintered layer was formed by performing a heat treatment at 850 ° C. for 5 minutes in a mixed gas (hydrogen 50% -nitrogen 50%) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 17 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
m zinc-plated substrate (60 μm thick copper foil)
It was applied to a thickness of 90 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, a sintered layer was formed by performing a heat treatment at 870 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 4.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 18 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
Substrate plated with nickel (m) (copper foil with a thickness of 60 μm)
Was applied to a thickness of 27 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. After that, a mixed gas (hydrogen 50% -nitrogen 50%)
By performing a heat treatment at 900 ° C. for 5 minutes in the inside, a sintered layer was formed and an electrode for a PTC thermistor was obtained. The center line average roughness R of the surface of the sintered layer thus formed is
a was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 19 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
It was applied to a substrate (a copper foil having a thickness of 60 μm) plated with m gold by a doctor blade method so as to have a thickness of 27 μm. Then, in nitrogen gas or air
The binder was removed by heat treatment at 50 ° C. Thereafter, a sintered layer was formed by performing a heat treatment at 950 ° C. for 5 minutes in a mixed gas (5% hydrogen-95% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Similar results were obtained when platinum was plated on the substrate instead of gold.

Example 20 100 g of vehicle A and 100 g of zinc powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste has a thickness of 60 μm
27μ by the doctor blade method on the copper foil (substrate)
m. Thereafter, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas or air. Then, the mixed gas (hydrogen 50
% -Nitrogen 50%) to form a sintered layer by performing a heat treatment at 418 ° C for 5 minutes to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 4.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 21 100 g of vehicle A and 100 g of platinum powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste has a thickness of 60 μm
27μ by the doctor blade method on the copper foil (substrate)
m. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, the mixed gas (hydrogen 50
% -Nitrogen 50%) at 1000 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the thus formed sintered layer was 2.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 22 100 g of vehicle A and 100 g of palladium powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste was applied to a 0.1 μm-thick Co-plated substrate (60 μm-thick iron foil) by a doctor blade method to a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a mixed gas (50% hydrogen-50 nitrogen)
%), A heat treatment was performed at 950 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm. The same center line average roughness Ra was obtained even when a copper foil or a nickel foil was used as the base.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 23 100 g of Vehicle A and 100 g of titanium powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 60μ thick
m nickel foil by the doctor blade method
It was applied to a thickness of μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, a sintered layer was formed by performing a heat treatment at 1050 ° C. for 5 minutes in a mixed gas (50% hydrogen—50% carbon dioxide gas) to obtain an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 24 100 g of vehicle A and 100 g of conductive powder (nickel-plated copper powder having a thickness of 0.5 μm and copper powder having an average particle diameter of 2 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick iron foil) by a doctor blade method to a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Thereafter, a sintered layer was formed by performing a heat treatment at 900 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm. In addition, even when the copper foil was used as the substrate, the same center line average roughness Ra was obtained.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

(Example 25) 100 g of vehicle A and conductive powder (average particle diameter of 2 μm plated with tin having a thickness of 0.5 μm)
(g copper powder) and kneaded well to obtain a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, the mixed gas (hydrogen 1
(0% -90% nitrogen) at 850 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

(Example 26) 100 g of vehicle A and conductive powder (average particle size of 2 μm plated with tin having a thickness of 0.5 μm)
(g of nickel powder of 100 µm) was sufficiently kneaded to obtain a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, a sintered layer was formed by performing a heat treatment at 830 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

(Example 27) 100 g of vehicle A and conductive powder (average particle size 2 plated with platinum having a thickness of 0.5 μm)
(μm iron powder) and 100 g, to give a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, the mixed gas (hydrogen 5
(0% -nitrogen 50%) at 950 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Similar results were obtained by using copper powder plated with zinc, gold, platinum, silver, chromium, cobalt, tin, indium or palladium as the conductive powder. Similar results were obtained by using copper powder plated with nickel phosphorus or nickel boron as the conductive powder. Also, as conductive powder, zinc, gold, platinum, chromium, cobalt, indium, copper, palladium,
Similar results were obtained using nickel powder plated with nickel phosphorus or nickel boron. Similar results were obtained using iron powder plated with tin, zinc, platinum, nickel, copper, silver, chromium, cobalt, indium, palladium, nickel phosphorus or nickel boron as the conductive powder. Also, as conductive powder, tin, zinc, platinum, nickel, copper, silver, cobalt, indium,
Similar results were obtained using chromium powder plated with gold, palladium, nickel phosphorus or nickel boron.
Also, tin, zinc, nickel, platinum, gold, copper, chrome,
Similar results were obtained using silver powder plated with cobalt, indium, palladium, nickel phosphorus or nickel boron. In addition, as conductive powder, tin, zinc,
Similar results were obtained using cobalt powder plated with platinum, nickel, copper, silver, chromium, indium, gold, palladium, nickel phosphorus or nickel boron. Similar effects were obtained by plating the above metal or alloy on zinc powder, platinum powder, gold powder, manganese powder, tungsten powder or molybdenum powder as conductive powder. The plating thickness of the conductive powder was preferably about 0.1 μm to 2 μm.

Example 28 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of silver powder having an average particle diameter of 3 μm and 5 g of tin powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, a sintered layer was formed by performing a heat treatment at 800 ° C. for 5 minutes in a mixed gas (hydrogen 15% -nitrogen 85%) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Good results were obtained when conductive powder having a silver powder content of 40 wt% or more (tin powder content of 60 wt% or less) was used as the conductive powder.

Example 29 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of copper powder having an average particle diameter of 3 μm and 5 g of zinc powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, a sintered layer was formed by performing a heat treatment at 825 ° C. for 5 minutes in a mixed gas (50% hydrogen—50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In the above example, good results were obtained even when the contents of copper powder and zinc powder in the conductive powder were changed.

Example 30 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of silver powder having an average particle size of 3 μm and 5 g of zinc powder having an average particle size of 2 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, a sintered layer was formed by performing a heat treatment at 825 ° C. for 5 minutes in a mixed gas (hydrogen 8% -nitrogen 92%) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 2.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In the conductive powder, good results were obtained even when the contents of silver powder and zinc powder were changed.

Example 31 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of nickel powder having an average particle diameter of 3 μm and 5 g of zinc powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
Was applied so as to have a film thickness. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. After that, a mixed gas (hydrogen 50% -nitrogen 50%)
In the inside, a heat treatment was performed at 825 ° C. for 5 minutes to form a sintered layer, and an electrode for a PTC thermistor was obtained. The center line average roughness Ra of the surface of the thus formed sintered layer was 2.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In the conductive powder, good results were obtained even when the contents of nickel powder and zinc powder were changed.

Example 32 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of nickel powder having an average particle diameter of 3 μm and 5 g of tin powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
Was applied so as to have a film thickness. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, a mixed gas (hydrogen 20% -nitrogen 80%)
In the inside, a heat treatment was performed at 825 ° C. for 5 minutes to form a sintered layer, and an electrode for a PTC thermistor was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Good results were obtained by using a conductive powder having a nickel powder content of 40% by weight or more (tin powder content of 60% by weight or less) as the conductive powder.

Example 33 100 g of vehicle A and 100 g of conductive powder (a mixture of 95 g of cobalt powder having an average particle diameter of 3 μm and 5 g of zinc powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
Was applied so as to have a film thickness. After that, about 6670 Pa
(50 mmHg) in nitrogen gas containing water vapor
The binder was removed by heat treatment at 00 ° C. Thereafter, a heat treatment was performed in a mixed gas (1% hydrogen-99% nitrogen) at 845 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In the above examples, good results were obtained even when the contents of nickel powder and zinc powder in the conductive powder were changed.

Example 34 100 g of vehicle A and 100 g of conductive powder (a mixture of 50 g of nickel powder having an average particle diameter of 3 μm and 50 g of copper powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. 0.5 μm thick paste
Nickel-plated substrate (copper foil with a thickness of 60 μm)
Was applied to a thickness of 100 μm by a doctor blade method. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Thereafter, a mixed gas (50% hydrogen-50 nitrogen)
%), A heat treatment was performed at 950 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the sintered layer thus formed was 6 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 35 100 g of Vehicle A and 100 g of conductive powder (a mixture of 5 g of indium powder having an average particle diameter of 3 μm and 95 g of copper powder having an average particle diameter of 3 μm) were sufficiently kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method for 27 μm.
Was applied so as to have a film thickness. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. After that, a mixed gas (hydrogen 50% -nitrogen 50%)
In the inside, a heat treatment was performed at 700 ° C. for 5 minutes to form a sintered layer, thereby obtaining a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In addition, good results were obtained by using a conductive powder having a copper powder content of 40 wt% or more (indium powder content of 60 wt% or less) as the conductive powder.

Example 36 100 g of vehicle A and 100 g of conductive powder (5 g of tin powder having an average particle size of 3 μm, 5 g of copper powder having an average particle size of 2 μm, and nickel powder 90 having an average particle size of 3 μm)
g) to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, at 700 ° C. in a mixed gas (10% hydrogen-90% nitrogen) at 5 ° C.
A sintered layer is formed by heat treatment for
The thermistor electrode was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

[0170] By using a conductive powder having a tin powder content of 60 wt% or less as the conductive powder,
Good results were obtained.

Example 37 100 g of vehicle A, 92 g of conductive powder (1 g of tin powder having an average particle size of 2 μm, 1 g of zinc powder having an average particle size of 2 μm, and nickel powder 90 having an average particle size of 2 μm)
g) and kneaded well to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, at 750 ° C. in a mixed gas (10% hydrogen-90% nitrogen),
A sintered layer is formed by heat treatment for
The thermistor electrode was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 2 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 38 100 g of Vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 6 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
Substrate plated with nickel (m) (copper foil with a thickness of 60 μm)
Was applied to a thickness of 60 μm by a doctor blade method. Then, in nitrogen gas, 400
The binder was removed by performing a heat treatment at a temperature of ° C. Then, a sintered layer was formed by performing a heat treatment at 900 ° C. for 10 minutes in a mixed gas (20% hydrogen-80% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed is
Was 7 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 39 130 g of vehicle A, 100 g of conductive powder (5 g of tin powder having an average particle size of 0.2 μm, 5 g of zinc powder having an average particle size of 0.2 μm, and 90 g of nickel powder having an average particle size of 0.2 μm) And kneaded well to obtain a paste. This paste is applied to a substrate (a copper foil having a thickness of 60 μm) by a die coater method (application speed: 10 mm / sec).
Was applied to a thickness of 5 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. Then, the mixed gas (hydrogen 5
(0% -nitrogen 50%) at 700 ° C. for 5 minutes to form a dense sintered layer.

Next, 5 wt% of butyral resin, 25 wt% of butyl acetate as a solvent and butyl cellosolve 70 were used.
wt% to obtain a vehicle. This vehicle 1
00 g and 100 g of conductive powder (a mixture of 5 g of tin powder having an average particle diameter of 2 μm, 5 g of zinc powder having an average particle diameter of 2 μm, and 90 g of nickel powder having an average particle diameter of 2 μm) were sufficiently kneaded to obtain a paste. This paste was applied on the dense sintered layer by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 400 ° C. in a nitrogen gas. afterwards,
70% in a mixed gas (50% hydrogen-50% nitrogen)
A heat treatment was performed at 0 ° C. for 5 minutes to form a sintered layer. Thus, an electrode for a PTC thermistor having two sintered layers, a dense sintered layer and a coarse sintered layer, was produced. The center line average roughness Ra of the surface of the sintered layer is 1.5 μm.
m.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

In addition, even when a conductive powder containing four or more kinds of metal powders added with copper powder or the like is used as the conductive powder,
The same results as those shown in Tables 1 and 2 were obtained.

In forming the dense sintered layer,
When a metal powder having an average particle size of 0.7 μm is used instead of the metal powder having an average particle size of 0.2 μm as the conductive powder, the firing temperature needs to be increased by 30 ° C., and the center line average roughness Although Ra was increased, the same results as in Tables 1 and 2 were obtained.

It is to be noted that a PTC thermistor electrode having two sintered layers can also be manufactured by the following method. That is,
First, 130 g of vehicle A and 100 g of conductive powder (a mixture of 5 g of tin powder having an average particle diameter of 0.2 μm, 5 g of zinc powder having an average particle diameter of 0.2 μm, and 90 g of nickel powder having an average particle diameter of 0.2 μm) are well kneaded. Thus, a first paste was obtained. This first paste is applied to a substrate (a copper foil having a thickness of 60 μm) by a die coater method (application speed: 10 mm / sec).
It was applied to a thickness of 5 μm, and the applied first paste was dried. Next, 5% of butyral resin was mixed with 25% of butyl acetate as a solvent and 70% of butyl cellosolve to obtain a vehicle. A mixture of 100 g of this vehicle, 5 g of 2 μm tin powder, 5 g of 2 μm zinc powder and 90 g of 2 μm nickel powder (conductive powder) was kneaded well to obtain a second paste. This second paste was applied to a copper foil on which the first paste was applied by a doctor blade method (application speed) to a thickness of 10 μm / sec to a thickness of 27 μm.
The binder was applied by applying the heat treatment at 400 ° C. and heat-treated at 400 ° C. in a nitrogen gas to remove the binder. Then, a sintered layer is formed by performing a heat treatment at 700 ° C. for 5 minutes in a mixed gas (50% of hydrogen-50% of nitrogen).
An electrode for a C thermistor was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 1.7 μm. A PTC thermistor was manufactured using the PTC thermistor electrode formed by the above manufacturing method. As a result, the resistance value before the test was 46 mΩ, the resistance value after the test was 68 mΩ, the rate of change in the resistance value was 48%, and the peel strength was 21.6 N / cm ^2.
A PTC thermistor of (2.2 kgf / cm ² ) was obtained.

Example 40 100 g of Vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
Substrate plated with nickel (m) (copper foil with a thickness of 60 μm)
Was applied to a thickness of 27 μm by a doctor blade method. Prior to plating, the copper foil as the base body was subjected to sandblasting using alumina having a 220 mesh pass to form irregularities on the surface. Then, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas. Then, at 890 ° C. in a mixed gas (hydrogen 50% -nitrogen 50%) at 5%.
A sintered layer is formed by heat treatment for
The thermistor electrode was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

In the above examples, good results were obtained irrespective of the type of the metal foil as the substrate, the presence or absence of plating, and the presence or absence of plating of the conductive powder.

Further, a PTC thermistor was produced in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 41 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is applied to the substrate (3
Chemical etching was performed using a specified nitric acid, and a 60 μm-thick copper foil having irregularities formed on its surface) was applied to a thickness of 27 μm by a doctor blade method. Thereafter, the binder was removed by performing a heat treatment at 500 ° C. in a nitrogen gas. Then, the mixed gas (hydrogen 5
(0% -nitrogen 50%) at 1000 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Various etchants can be used for etching the substrate to form irregularities. By using a sulfuric acid-hydrogen peroxide-based etchant, particularly large irregularities can be formed. Could be formed. By selecting the etchant, good results were obtained irrespective of the type of the base metal foil, the presence or absence of plating, and the presence or absence of plating of the conductive powder.

Example 42 100 g of vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 2 μm were sufficiently kneaded to obtain a paste. This paste is applied to a thickness of 0.
Substrate plated with 1 μm nickel (3
It was applied to a thickness of 27 μm by a doctor blade method on a 60 μm-thick copper foil having irregularities formed on the surface by performing electrolytic etching in a prescribed sodium chloride aqueous solution. Then, in nitrogen gas 39
The binder was removed by heat treatment at 0 ° C.
Thereafter, a sintered layer was formed by performing a heat treatment at 890 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintering layer thus formed is:
It was 3.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Similar results were obtained by using a copper foil having an uneven surface formed by metallikon (metal spray coating method) as the substrate.

(Example 43) 4% by weight of ethylcellulose
And 48 wt% of ethanol as a solvent and toluene 4
And 8 wt% to obtain a vehicle. 100 g of this vehicle and nickel powder (conductive powder) having an average particle size of 2 μm
100 g were kneaded well to obtain a paste. This paste was coated on a 1 μm-thick nickel-plated substrate (thickness: 6 μm).
0μm copper foil) by the doctor blade method
m. Then, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas. Thereafter, a mixed gas (50% hydrogen-50 nitrogen)
%), A heat treatment was performed at 900 ° C. for 5 minutes to form a sintered layer, thereby obtaining an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the thus formed sintered layer was 2.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 44 100 g of vehicle A and 100 g of conductive powder (5 g of iron powder having an average particle diameter of 2 μm plated with nickel having a thickness of 0.5 μm and nickel having an average particle diameter of 2 μm plated with nickel having a thickness of 0.5 μm) Copper powder 5g and average particle size 2
mixture with 90 g of nickel powder of 90 μm),
A paste was obtained. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 27 μm. Thereafter, the binder was removed by heat treatment at 450 ° C. in a nitrogen gas. Then, a sintered layer is formed by performing a heat treatment at 900 ° C. for 5 minutes in a mixed gas (50% hydrogen—50% nitrogen) to form a sintered layer.
An electrode for a C thermistor was obtained. The center line average roughness Ra of the surface of the sintered layer thus formed was 2 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 45 80 g of vehicle A, 100 g of conductive powder (5 g of tin powder having an average particle size of 2 μm, 5 g of zinc powder having an average particle size of 2 μm, and nickel powder 9 having an average particle size of 50 μm)
And a mixture with 0 g) to obtain a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 150 μm. Then, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas. Then, the mixed gas (hydrogen 5
(0% -nitrogen 50%) at 700 ° C. for 15 minutes to form a sintered layer to obtain an electrode for a PTC thermistor. The center line average roughness Ra of the surface of the thus formed sintered layer was 20 μm.

The conductive powder has an average particle diameter of 50.
By using a conductive powder having a size of not more than μm, the precipitation of the conductive powder in the paste could be suppressed, and the paste could be easily applied to the substrate.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

By using a conductive powder having a nickel powder content of 40 wt% or more as the conductive powder, the adhesive strength with the copper foil was particularly increased.

Example 46 110 g of vehicle A, 100 g of conductive powder (5 g of tin powder having an average particle diameter of 0.7 μm, 5 g of zinc powder having an average particle diameter of 0.7 μm, and 90 g of nickel powder having an average particle diameter of 0.7 μm) And kneaded well to obtain a paste. This paste was applied to a 1 μm-thick nickel-plated substrate (60 μm-thick copper foil) by a doctor blade method to a thickness of 27 μm.
Then, the binder was removed by performing a heat treatment at 390 ° C. in a nitrogen gas. Thereafter, a sintered layer was formed by performing a heat treatment at 700 ° C. for 15 minutes in a hydrogen gas to obtain a PTC thermistor electrode. The center line average roughness R of the surface of the sintered layer thus formed is
a was 0.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

[0200] By using a conductive powder having a nickel powder content of 70 wt% or more as the conductive powder, the adhesion to the copper foil was particularly increased.

In the above embodiment, a cellulose resin such as methylcellulose, ethylcellulose, nitrocellulose, acrylic resin, polyacetal resin, polyvinyl alcohol resin or rosin may be used instead of butyral resin.

Example 47 100 g of an aqueous solution containing 3.5% by weight of methylcellulose and an average particle size of 2 μm
And 90 g of nickel powder (conductive powder) was well kneaded to obtain a paste. This paste was applied to a copper foil (substrate) having a thickness of 60 μm by a doctor blade method, a reversible roll method or a screen printing method so as to have a film thickness of 27 μm (application speed: 10 mm / sec). Thereafter, rolling roll treatment or hot press treatment was performed at a temperature of 350 ° C. in a nitrogen gas containing preferably 5% or less of hydrogen gas. Thereafter, the binder was removed by heat treatment at 450 ° C. Then, the mixed gas (hydrogen 35
% -Nitrogen 65%) at 950 ° C. for 5 minutes to form a sintered layer to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 2 μm.

It is to be noted that a higher temperature (for example, 350.degree. C.)
Above), the adhesion between the substrate and the nickel powder was increased.

As the substrate, nickel foil, nickel-plated iron foil, nickel-plated copper foil, nickel, copper, silver, gold, palladium, zinc, chromium, platinum, tin, cobalt, indium, Similar results were obtained using phosphor bronze, brass, nickel silver, nickel phosphorus, nickel boron, or a metal foil plated with these alloys or their compounds.

Further, as the conductive powder, copper, silver, zinc,
Palladium, gold, platinum, cobalt, iron, titanium, nickel phosphorus, nickel boron, molybdenum, tungsten,
Good results were obtained using conductive powders of manganese, lead, or alloys containing these, or conductive powders plated with these.

In particular, good results were obtained when the substrate and the conductive powder were plated with nickel phosphorus or nickel boron.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

Example 48 100 g of Vehicle A and 100 g of nickel powder (conductive powder) having an average particle size of 3 μm were sufficiently kneaded to obtain a paste. This paste is 1μ thick
substrate with a thickness of 60 μm
m of copper foil) by a doctor blade method so as to have a thickness of 27 μm. Then, the binder was removed by performing a heat treatment at 450 ° C. in a nitrogen gas or air. Then, a sintered layer was formed by performing a heat treatment at 800 ° C. for 5 minutes in a mixed gas (50% hydrogen-50% nitrogen) to obtain a PTC thermistor electrode. The center line average roughness Ra of the surface of the sintered layer thus formed was 3.5 μm.

Similar results were obtained when using a substrate plated with nickel boron instead of nickel phosphorus.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

As the substrate, nickel foil, nickel-plated iron foil, nickel-plated copper foil, nickel, copper, silver, gold, palladium, zinc, chromium, platinum, tin, cobalt, indium, Similar results were obtained using phosphor bronze, nickel silver, nickel phosphorus, nickel boron, or an alloy or a metal foil plated with these compounds.

Further, as the conductive powder, copper, silver, zinc,
Good results were obtained using conductive powders made of palladium, gold, platinum, cobalt, iron, titanium, nickel phosphorus, nickel boron, or plated conductive powders.

Comparative Example A copper foil (electrolytic copper foil) formed by a plating method was plated with nickel having a thickness of 1 μm.
The current density was increased, and nickel was further deposited on the nickel plating by electrodeposition to roughen the surface. The center line average roughness Ra of the surface of the nickel plating layer thus formed was 1.5 μm.

Further, a PTC thermistor was manufactured in the same manner as in Example 1 using the two PTC thermistor electrodes. Then, under the same conditions as in Example 1, an overcurrent application cycle test and a peeling test were performed (see Tables 1 and 2).

As shown in Table 1, in the PTC thermistor of the comparative example, the rate of change in resistance was as large as 50% or more. Then, in the PTC thermistor of the comparative example, after the overcurrent application cycle test, even if an attempt was made to apply a guaranteed energizing current (specifically, 1 A), it could not be applied. On the other hand, in the PTC thermistors of Examples 1 to 48, the resistance value change rate was 50%.
% Or less. In addition, the PT of Examples 1 to 48
With the C thermistor, a guaranteed energizing current could be applied even after the overcurrent application cycle test.

Further, as shown in Table 2, the PT of the comparative example was
In the C thermistor, the peel strength between the PTC thermistor electrode and the conductive polymer was low, whereas in the PTC thermistors of Examples 1 to 48, 9.8 N /
A peel strength of at least cm ² (1 kgf / cm ² ) (a value having no practical problem) was obtained.

The embodiments of the present invention have been described with reference to the examples. However, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

[0218]

As described above, the PTC thermistor electrode of the present invention includes a conductive base and a sintered layer formed on the base, and the sintered layer is formed by firing a conductive powder. This is a conductive sintered layer formed by tying. Therefore, according to the PTC thermistor of the present invention,
PTC with high adhesion to conductive polymer and easy to manufacture
The thermistor electrode is obtained.

The method of manufacturing an electrode for a PTC thermistor of the present invention comprises a first step of applying a paste containing a conductive powder on the surface of a conductive substrate, and a heat treatment of the paste to form the conductive layer. Forming a sintered layer containing a conductive powder. Therefore, according to the above manufacturing method, the electrode for a PTC thermistor of the present invention can be easily manufactured. In particular, according to the above manufacturing method, the center line average roughness can be easily controlled by changing the shape and particle size of the conductive powder in the paste.

[0220] The PTC thermistor of the present invention is a PTC thermistor including a pair of electrodes and a conductive polymer disposed between the pair of electrodes, wherein the electrode is the above-mentioned electrode for a PTC thermistor of the present invention. It is characterized by. Therefore, according to the PTC thermistor of the present invention, the PT
A PTC thermistor having a large adhesive strength between the C thermistor electrode and the conductive polymer and having a small rate of change in resistance even when an overcurrent is repeatedly applied is obtained.

[Brief description of the drawings]

FIG. 1 shows an electrode for a PTC thermistor of the present invention.
It is sectional drawing which shows an example.

FIG. 2 shows the PTC thermistor electrode of the present invention.
It is sectional drawing which shows another example.

FIG. 3 shows the PTC thermistor electrode of the present invention.
It is sectional drawing which shows another example.

FIG. 4 shows the PTC thermistor electrode of the present invention.
It is sectional drawing which shows another example.

FIG. 5 is a schematic view showing a method for measuring a center line average roughness Ra.

FIG. 6 is a process chart showing an example of a method for producing an electrode for a PTC thermistor of the present invention.

FIG. 7 is a schematic view showing an example of a manufacturing apparatus for a method for manufacturing an electrode for a PTC thermistor of the present invention.

FIG. 8 is a sectional view showing an example of a PTC thermistor of the present invention.

[Explanation of symbols]

 10, 10a, 10b, 10c PTC thermistor 11, 11a Base 12 Sintered layer 12a First sintering layer 12b Second sintering layer 13 Metal film 14 Concavo-convex shape 61 Conductive powder 62 Paste 80 PTC thermistor 81 Conductive polymer Ra center line average roughness L reference length

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiro Kume 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Junji Kojima 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. CA33 JA22 JA30 JA38 KA37 5E034 AA07 AB01 AC10 DA02 DC03 DC05 DC09 DE07 DE09 DE16

Claims (25)

[Claims] 1. A sintering device comprising: a conductive substrate; and a sintered layer formed on the substrate, wherein the sintered layer is formed by sintering a conductive powder. An electrode for a PTC thermistor, wherein the electrode is a sintered layer having an uneven shape on the surface. 2. The sintered body according to claim 1, wherein said sintered layer has a center line average roughness Ra.
2. The P according to claim 1, wherein the P is 0.5 μm or more and 20 μm or less.
Electrode for TC thermistor. 3. The conductive powder has an average particle size of 0.1 μm.
2. The electrode for a PTC thermistor according to claim 1, which is at least 50 μm. 4. The electrode for a PTC thermistor according to claim 1, wherein a metal film is formed on a surface of said conductive powder. 5. The PTC thermistor electrode according to claim 4, wherein said base is made of a metal material, and said metal film is made of the same metal material as said base. 6. The PTC thermistor electrode according to claim 4, wherein the base is made of a metal material, and the metal film is made of a metal material having a lower melting point than the base. 7. The PTC thermistor electrode according to claim 1, wherein the conductive powder includes a powder in which a plurality of conductive particles are formed in a chain. 8. The conductive powder comprises a first conductive powder.
And a second powder having conductivity, wherein the first
The PTC according to any one of claims 1 to 3, wherein the average particle size of the powder is 2 times or more the average particle size of the second powder.
Electrode for thermistor. 9. The PTC thermistor electrode according to claim 8, wherein the content of the second powder contained in the conductive powder is 60 wt% or less. 10. The PTC thermistor electrode according to claim 1, further comprising a metal film formed between said base and said sintered layer. 11. The metal film is formed of nickel, copper, silver,
The PTC thermistor electrode according to claim 10, comprising at least one element selected from gold, palladium, titanium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt and indium. 12. The electrode for a PTC thermistor according to claim 1, wherein the substrate has an uneven shape on the surface. 13. The sintered layer includes a first sintered layer and a second sintered layer laminated from the substrate side, wherein the first sintered layer has an average grain size of 0.1 mm. 1 μm or more and 1 μm
The second sintered layer is a sintered layer formed by sintering a conductive powder having an average particle diameter of 1 μm or more. Item 4. An electrode for a PTC thermistor according to any one of Items 1 to 3. 14. The method according to claim 14, wherein the conductive powder is iron, nickel,
Copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt,
14. The PTC thermistor electrode according to claim 1, comprising a metal material containing at least one element selected from indium and titanium. 15. The PTC thermistor electrode according to claim 14, wherein the base is made of a metal material containing at least one element selected from iron, copper and nickel. 16. A first step of applying a paste containing a conductive powder on the surface of a substrate having conductivity, and forming a sintered layer in which the conductive powder is sintered by heat-treating the paste. A method for manufacturing an electrode for a PTC thermistor, comprising: 17. The conductive powder has an average particle size of 0.1 μm.
The method for producing an electrode for a PTC thermistor according to claim 16, wherein the diameter is not less than m and not more than 50 µm. 18. The method of manufacturing an electrode for a PTC thermistor according to claim 16, further comprising a step of forming a metal film on the surface of the base before the first step. 19. The method according to claim 16, further comprising a step of forming a concavo-convex shape on the surface of the base before the first step.
Or a method for producing a PTC thermistor electrode according to item 17. 20. The conductive powder has an average particle size of 0.1.
μm or more and 1 μm or less, after the second step, a paste containing a conductive powder having an average particle size of 1 μm or more was applied to the sintered layer and then heat-treated, whereby the paste was laminated on the sintered layer. The method for producing an electrode for a PTC thermistor according to claim 16 or 17, further comprising a third step of forming a sintered layer. 21. The method of manufacturing an electrode for a PTC thermistor according to claim 16, wherein the first step further comprises a step of drying and rolling the paste applied to the base after applying the paste. . 22. The method for manufacturing an electrode for a PTC thermistor according to claim 16, wherein the heat treatment is performed in a reducing atmosphere. 23. The conductive powder is composed of iron, nickel,
Copper, silver, gold, palladium, zinc, molybdenum, tungsten, manganese, lead, chromium, platinum, tin, cobalt,
The method for producing an electrode for a PTC thermistor according to any one of claims 16 to 22, comprising a metal material containing at least one element selected from indium and titanium. 24. The method of manufacturing an electrode for a PTC thermistor according to claim 23, wherein said base is made of a metal material containing at least one element selected from iron, copper and nickel. 25. A PTC thermistor including at least a pair of electrodes and a conductive polymer disposed between the pair of electrodes, wherein the electrodes are for the PTC thermistor according to claim 1. PT characterized by being an electrode
C thermistor.