JPH10208902A - Production of organic ptc thermistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable organic PTC(positive temperature coefficient of resistivity) thermistor exhibiting low resistance at the nonoperating time and having high degree of freedom in the selection of material. SOLUTION: The method for producing an organic PTC having a thermistor element where conductive particles are diffused into a crystalline polymer and an electrode provided on the surface comprises a step for removing the crystalline polymer selectively to expose the conductive particles to the surface of the thermistor element, and a step for forming electrodes. The selective removing step utilizes a reactive ion etching method, UV-irradiation, exposure to atmosphere containing ozone, combination of UV-irradiation and exposure to atmosphere containing ozone, laser irradiation, or the like. The electrode comprises a resin electrode layer where conductive electrode material particles are dispersed into a resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive temperature coefficient of resistance (PTC).
The present invention relates to a method for producing an organic PTC thermistor using a crystalline high-molecular polymer among PTC thermistors exhibiting high sensitivity.

[0002]

2. Description of the Related Art An organic PTC thermistor has a structure in which conductive particles such as carbon black and metal are dispersed in a crystalline polymer, and electrodes are provided on the surface of a thermistor body. Compared to thermistors,
Since the specific resistance at room temperature (the specific resistance during non-operation) is low, it is suitable for applications in which a large current flows, and can be miniaturized, and the resistance change rate (maximum resistance value / room temperature resistance value) is large. It is known to have excellent properties. Organic PT
The C thermistor can be used, for example, for a self-control type heater, a temperature detector, an overcurrent protection element, and the like.

[0003] As a method of providing an electrode on a body of an organic PTC thermistor, a method of pressing a metal foil (US Pat. No. 4,426,633) is widely known. However, when this method is used, the electrical contact between the element body and the electrode cannot be made uniform, so that the contact resistance of the electrode increases. For this reason, the resistance value during non-operation becomes high, which is not preferable for an application in which a large current flows.

For this reason, in Japanese Patent Publication No. 4-44401, an electrode is formed by an electroplating method or a chemical plating method after a surface of a body is etched in advance to expose a conductive filler near the surface of the body. A method has been proposed. In this publication, a chromic acid mixed solution as an etching means,
Surface treatment with para-xylene, sandblasting,
Surface treatment with sandpaper is mentioned.

However, when a wet method using a chromic acid mixed solution or para-xylene is used for etching the thermistor body surface, for example, if metal, oxide, or non-oxide particles are used as the conductive particles, high crystallinity is obtained. Since it is difficult to selectively etch only the molecular polymer, it is practically applicable only when using limited conductive particles such as carbon black. The wet etching method is not preferable when a water-soluble crystalline polymer is used. For example, an organic solvent having an aromatic ring such as para-xylene cannot be used for polyethylene oxide or the like. Also, even if the crystalline polymer is water-insoluble,
Since infiltration of the etching solution into the element body is unavoidable, thermistor characteristics may become unstable and reliability may be reduced.

When sandblasting is used for etching the surface of the thermistor body, the selectivity at the time of selectively removing the polymer becomes insufficient. Further, physical damage to the thermistor body and contamination with impurities may occur, which may cause deterioration of the thermistor characteristics.

[0007] The plating solution is usually a strongly alkaline or strongly acidic aqueous solution, which comes into direct contact with the thermistor body during plating. Therefore, when the plating method is used, a water-soluble polymer material such as polyethylene oxide cannot be used as the crystalline polymer of the thermistor body. In addition, even when a water-insoluble polymer material such as polyethylene is used, there is a problem that the plating solution is unavoidably infiltrated into the element body, which causes instability of the thermistor characteristics and a decrease in reliability. In particular, when metal particles or particles having a conductive coating on the surface are used as the conductive particles to be contained in the thermistor body, the conductivity of the conductive particles is deteriorated, and the reliability is significantly reduced.

When the conductive particles are exposed by etching the surface of the thermistor body, irregularities are formed on the surface of the body. When a plating layer is formed directly on these irregularities, it is difficult to make the thickness uniform. Specifically, the plating layer grows in an island shape in a manner emphasizing irregularities on the surface of the element body. For this reason, the electrical resistance in the in-plane direction of the plating layer increases, and the mechanical strength decreases. In such a state, for example, in the case of a PTC thermistor having a relatively large area used for flowing a large current, the current flowing through the thermistor element becomes small at a position far from the lead wire, and conversely, near the lead wire In this case, the resistance becomes excessively large, which causes a decrease in the non-linearity of the electric resistance change and a decrease in the allowable current value.

In the organic PTC thermistor, PTC
During operation, the element body undergoes significant thermal expansion, causing excessive stress on the electrodes. Since the electrode composed of the plating layer has low mechanical strength, cracks may occur in the electrode due to repetition of the PTC operation, or the electrode may be partially peeled off, resulting in reliability problems such as an increase in electric resistance. It is a factor that arises.

US Pat. No. 4,689,475 describes an organic PTC thermistor having an electrode with a microrough surface. The electrode having the fine rough surface is a metal foil formed by electroplating, electrodeposition, or the like. Also in this specification, the effect of improving the adhesiveness of the electrode is described.

However, a metal foil having a specific rough surface capable of improving the adhesion and contact resistance of the electrode, particularly a Ni foil, is expensive, while a Cu foil is relatively inexpensive but has insufficient corrosion resistance. It is. Also, according to the study of the present inventors,
In the organic PTC thermistor, only a few conductive particles existing near the element body surface are exposed from the element body surface, and most of the conductive particles are coated with a high-molecular polymer having a thickness of about several micrometers. I understand. For this reason, roughening of the electrode alone is not enough to stably reduce the contact resistance.

Also, in US Pat. No. 4,444,708, two electrodes are covered with an amorphous high-conductivity rubber and embedded in a PTC material, thereby improving the adhesion strength between the electrodes and the PTC material. Improvements have been made to improve the stability of the resistance value and the reliability. The amorphous high-conductivity rubber in the specification has non-PTC characteristics. In this publication, epichlorohydrin containing a large amount of carbon black is mentioned as a preferable example of the amorphous high conductivity rubber. The specification states that if necessary, the electrode surface may be formed in a projecting shape (for example, a minute projecting shape) to improve the contact resistance and the adhesive force.

However, the specification does not disclose that the interface between the PTC material and the amorphous high-conductivity rubber may be etched. In a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer, the conductive particles near the element surface are covered with the polymer as described above, so that the thermistor element and the electrode If the amorphous high-conductivity rubber described in the same specification is interposed between them, simply joining them together will increase the contact resistance.

[0014]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a highly reliable organic P which has a low resistance value during non-operation and a high reliability.
To provide a TC thermistor. A second object of the present invention is to provide an organic PTC thermistor having a low resistance value during non-operation, high reliability, and a high degree of freedom in material selection.

[0015]

This and other objects are achieved by any one of the following constitutions (1) to (13). (1) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element, comprising: The crystalline polymer is selectively removed from the surface of the thermistor body by a treatment method,
Organic P having a selective removal step of exposing conductive particles to the thermistor body surface and an electrode forming step of forming an electrode
Manufacturing method of TC thermistor. (2) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the thermistor element surface, the method comprising: A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by a reactive ion etching method to expose conductive particles to the surface of the thermistor body; and an electrode forming step of forming an electrode. A method for producing an organic PTC thermistor. (3) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the thermistor element surface, the method comprising: A selective removal step of selectively removing the crystalline high molecular polymer from the surface of the thermistor body by irradiating the same and exposing the conductive particles to the surface of the thermistor body, and an electrode forming step of forming an electrode. A method for producing an organic PTC thermistor. (4) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the thermistor element surface, the method comprising: And selectively exposing the conductive particles to the thermistor body surface by selectively removing the crystalline high-molecular polymer from the surface of the thermistor body by exposing to the ozone-containing atmosphere and exposing the electrode. A method for producing an organic PTC thermistor having an electrode forming step of forming. (5) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the thermistor element surface, comprising: A selective removal step of selectively removing the crystalline high molecular polymer from the surface of the thermistor body by exposing to the containing atmosphere to expose conductive particles to the thermistor body surface; and an electrode forming step of forming an electrode A method for producing an organic PTC thermistor comprising: (6) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer, and an electrode provided on the surface of the thermistor element, comprising: A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by irradiating light to expose conductive particles to the surface of the thermistor body; and an electrode forming step of forming an electrode. A method for producing an organic PTC thermistor having: (7) In the electrode forming step, when forming an electrode including a resin electrode layer having a configuration in which conductive electrode material particles are dispersed in a resin and operating as a PTC thermistor, the resistance value of the electrode is reduced by the thermistor. 1/10 of the element's resistance
The method for producing an organic PTC thermistor according to any one of the above (1) to (6), wherein the organic PTC thermistor is 0 or less. (8) A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer, and an electrode provided on the surface of the thermistor element, the method comprising: A selective removal step of selectively removing the crystalline polymer from the surface of the element to expose the conductive particles to the surface of the thermistor element; and a resin having a configuration in which conductive electrode material particles are dispersed in the resin. An electrode forming step of forming an electrode including an electrode layer, wherein when operating as a PTC thermistor, an organic PTC thermistor in which the resistance value of the electrode is 1/100 or less of the resistance value of the thermistor body is manufactured. A method for producing an organic PTC thermistor. (9) The method for producing an organic PTC thermistor according to the above (8), wherein a reverse sputtering method is used in the selective removal step. (10) The method for producing an organic PTC thermistor according to the above (8), wherein the selective removal step uses a sandblast method. (11) The method according to (7) to (10), wherein the electrode includes a metal electrode layer, and the metal electrode layer is formed on the resin electrode layer.
The method for producing an organic PTC thermistor according to any one of the above. (12) The method for manufacturing an organic PTC thermistor according to (11), wherein the metal electrode layer is formed by a plating method. (13) The method for producing an organic PTC thermistor according to the above (11), wherein the resin electrode layer has adhesiveness, and the metal electrode layer is a metal foil.

[0016]

According to the present invention, in order to reduce the contact resistance between the thermistor element and the electrode to reduce the resistance value during non-operation, plasma treatment, reactive ion etching, ultraviolet light, an ozone-containing atmosphere, laser light Is used to selectively remove the crystalline high molecular polymer on the thermistor body surface. Each of these methods is different from a physical removal method such as a sand blast method described in Japanese Patent Publication No. 4-44401 or a wet etching method, and has substantially no adverse effect on the thermistor body. An organic PTC thermistor having high reliability and a low resistance value during non-operation can be obtained because of good selectivity when etching a polymer.

In Japanese Patent Publication No. Hei 4-44401, since the electrodes are formed by plating, the usable crystalline high molecular polymer and conductive particles are limited.
Even when a crystalline polymer or conductive particles that can be used are used, deterioration of these characteristics due to the plating solution becomes a problem. On the other hand, in the present invention, if the electrode is composed of the resin electrode layer and the metal electrode layer, the plating method can be used for forming the metal electrode regardless of the type of the crystalline polymer and the conductive particles, Deterioration can also be suppressed. Therefore, an organic PTC thermistor having a high degree of freedom in material selection and high reliability is realized.

This publication describes, as pretreatments for electroplating, surface oxidation with an ozone-containing gas and imparting hydrophilicity by plasma irradiation. However, the pretreatment of electroplating is a treatment for modifying the surface to be plated, and only changes the surface at a depth of the order of submicrons, which is completely different from the selective removal treatment of the crystalline polymer in the present invention. different.

Further, Japanese Patent Application Laid-Open No. 63-321601 describes a method of forming an electrode on a roughened element body surface to strengthen the bonding of the electrode and improve the ohmic property. . In this publication, reverse sputtering and sand blast are mentioned as surface roughening means, and a sputtering method or an ion plating method is mentioned as an electrode forming method. However, there is no description about the resin electrode layer used in the present invention. In addition, the sandblast method has poor selectivity when etching a crystalline polymer, and the reverse sputtering method has poor selectivity as compared with the reactive ion etching method.

[0020]

DETAILED DESCRIPTION OF THE INVENTION Organic PT produced according to the present invention
FIG. 1 shows a configuration example of the C thermistor. The organic PTC thermistor shown in FIG. 1 has a thermistor element 2 having a configuration in which conductive particles are dispersed in a crystalline polymer (hereinafter, sometimes simply referred to as a polymer), and the thermistor element interposed therebetween. And a pair of electrodes 3 provided.

Production of the Thermistor Element The polymer used in the present invention is not particularly limited, and any polymer can be used without limitation as long as it can exhibit PTC characteristics when the conductive particles are dispersed to form an element.

The polymer usable in the present invention includes, for example, polyethylene, polyethylene oxide, t-4-polybutadiene, polyethylene acrylate, ethylene-
Ethyl acrylate copolymer, ethylene-acrylic acid copolymer, polyester, polyamide, polyether, polycaprolactam fluorinated ethylene-propylene copolymer, chlorinated polyethylene, chlorosulfonated ethylene,
Ethylene-vinyl acetate copolymer, polypropylene, polystyrene, styrene-acrylonitrile copolymer, polyvinyl chloride, polycarbonate, polyacetal, polyalkylene oxide, polyphenylene oxide, polysulfone, fluorine-based resin and the like, and at least one of these. It may be used. Specifically, it may be appropriately selected according to the method of forming the electrodes, the required PTC thermistor characteristics, and the like. For example, when the thermistor body contacts the plating solution in the manufacturing process, it is preferable to avoid using a water-soluble polymer. However, when a resin electrode layer is provided on the surface of the element body and a metal electrode layer is formed on the surface by a plating method, a water-soluble polymer can be used without any problem.

Preferred specific examples of the polymer include nylon 12 and polyethylene oxide (PEO). Of these, polyethylene oxide is preferable when the operation is performed at a relatively low temperature of about 60 to 70 ° C, and nylon 12 is preferable when the operation is performed at a temperature of about 140 to 160 ° C. In particular, polyethylene oxide is preferred for the purpose of lowering the operating temperature.

The polyethylene oxide has a weight average molecular weight Mw of preferably 2,000,000 or more, more preferably 300,000,000 or more.
10,000 to 6 million. If Mw is too small, the viscosity at the time of melting will be too low, and the dispersibility of the conductive particles will deteriorate, making it difficult to lower the resistance at room temperature. Mw20
Polyethylene oxide having a melting point of 65 to 70
At about ° C, the density is about 1.15 to 1.22 g / cm ³ .

Nylon 12 is a lactam polymer of 12-aminododecanoic acid, having a melting point of 177 ° C. and a density of 1.
It is preferably 0.3 g / cm ³ and Mw of 20,000 to 50,000.

As the fluorine resin, polyvinylidene fluoride is preferred. Polyvinylidene fluoride exhibits self-extinguishing properties. The self-extinguishing property is a property that, even after ignition, the fire extinguishes naturally when the flame is kept away. For this reason, polyvinylidene fluoride is suitable for applications in which ignition is possible.

The conductive particles used in the present invention are not particularly limited, and may be used without limitation as long as they have the necessary conductivity.

The conductive particles usable in the present invention include: carbon-based particles: carbon black, graphite, etc .; metal particles: Ni, Ti, Cu, Ag, Pd, Au, Pt.
Oxide-based conductive particles: ZnO, SnO ₂ , ITO, In ₂
O ₃ etc .; non-oxide conductive particles: TiN, WC, TiC, TiB
₂ , ZrC, ZrN, etc .; conductive coating particles: carbon black, Al
Examples include particles in which an Ag plating layer is formed on particles such as ₂ O ₃ and TiO ₂ , and particles in which a Pd plating layer is formed on particles such as BaTiO ₃ . At least one kind may be selected from these conductive particles. Specifically, it may be appropriately selected according to the electrode forming method, the required PTC thermistor characteristics, and the like. For example, when the thermistor body contacts the plating solution in the manufacturing process, it is preferable to avoid using metal particles or conductive coating particles. However,
When a resin electrode layer is provided on the surface of the element body and a metal electrode layer is formed on the surface by plating, metal particles and conductive coating particles can be used without any problem.

Although the specific resistance of WC among the above-mentioned conductive particles is not particularly low as compared with other non-oxide-based conductive particles, when dispersed in the thermistor body, the volume in the body is small. Even if the ratio is the same as that of the other non-oxide-based conductive particles, the resistance of the entire element at room temperature is significantly reduced. Therefore, when WC is used, a sufficiently low room temperature resistance can be obtained even if the ratio of the conductive particles in the element body is reduced.
For this reason, the torque at the time of kneading the conductive particles and the polymer becomes small, and molding becomes easy.

The shape of the conductive particles is not particularly limited, and may be any of flakes, spheres, irregular shapes, etc., but is preferably, for example, disclosed in JP-A-5-47503 or Japanese Patent Application No. 8-332799. The one having a spike-shaped protrusion as described in (1) is used.

The preferred average particle size of the conductive particles varies depending on the type, shape, diameter measuring method and the like, but is usually about 0.01 to 10 μm, preferably 0.04 to 5 μm.
It is about μm.

The ratio (volume ratio) of the conductive particles in the body is
What is necessary is just to determine appropriately so that the required PTC thermistor characteristics are obtained and the resistance value is sufficiently low during non-operation. The preferred ratio of the conductive particles {conductive particles / (polymer + conductive particles)} varies depending on various conditions such as the type and shape of the conductive particles, but is preferably 15 to 65% by volume, more preferably. 20 to 50% by volume. If the ratio of the conductive particles is too low, the resistance value of the element increases, which is not preferable for use in flowing a large current. Further, when the electrodes are formed by the electroplating method, it is difficult to form the electrodes. On the other hand, if the ratio of the conductive particles is too high, uniform dispersion becomes difficult when kneading the conductive particles with the polymer, and characteristics such as withstand voltage tend to deteriorate. Also, PT
The C characteristic may not be exhibited.

The thermistor body is usually manufactured by the following procedure. First, conductive particles are added to a crystalline polymer, and the mixture is kept at a temperature equal to or higher than the softening point of the polymer and sufficiently kneaded until the conductive particles are uniformly dispersed. Next, it is formed into a sheet or the like using an extrusion molding machine or a roll molding machine or the like, and is subjected to a crosslinking treatment as necessary, to obtain a thermistor body.

Selective Removal Step After the production of the thermistor body, the crystalline polymer is selectively removed from the surface of the thermistor body to expose the conductive particles to the thermistor body surface. The reason for providing the selective removal step is as follows.

It is expected that both are distributed on the surface of the thermistor body manufactured by the above-described method in accordance with the mixing ratio of the conductive particles and the crystalline polymer. However, according to the study of the present inventors, it was found that the surface of the conductive particles near the element body surface was covered with a polymer thin film as described above. Specifically, although it depends on the combination of the conductive particles and the polymer, the results of surface observation with a scanning electron microscope and measurement of the surface conductivity with an atomic force microscope show that the conductivity existing near the element body surface is high. It was found that at most about 90% of the particles were covered by a polymer layer having a thickness of about 0.1 to 3 μm.

When electrodes are formed on the surface of such a body,
The contact resistance between the electrode and the element body is significantly increased, which is not preferable. Therefore, in the present invention, a selective removal step is provided in order to remove the polymer film covering the conductive particles existing near the element body surface.

The removal depth of the polymer may be appropriately determined according to the combination of the conductive particles and the polymer so that the conductive particles are sufficiently exposed, but is preferably 0.1 to 20.
μm, more preferably 0.5 to 10 μm. If the depth of the selective removal is too shallow, the effect of the selective removal becomes insufficient. On the other hand, if the depth for selective removal is too deep, the conductive particles completely float from the polymer, which causes a decrease in electrode adhesion strength and an increase in electrode resistance.

The method used for the selective removal of the polymer is such that the combination of the two can be selectively removed from the thermistor body composed of the polymer and the conductive particles so as not to damage the thermistor body. The method may be appropriately selected in consideration of the method, and is not particularly limited. However, in the present invention, for example, a method described below is preferably used.

[0039] In the selective removal method This method utilizes a gas discharge plasma, to generate a gas plasma by introducing a discharge gas into the vacuum chamber was placed a thermistor body, it is produced by plasma ion bombardment and plasma The polymer is selectively removed by the active oxidizing gas. As the discharge gas, an inert gas such as Ar, an oxidizing gas such as oxygen, or a mixed gas thereof may be used, but a gas containing at least an oxidizing gas is preferably used. Specifically, a plasma treatment method, a reactive ion etching method, a reverse sputtering method, or the like may be used. In the reactive ion etching method, an oxidizing gas such as oxygen is used as a discharge gas, and in the reverse sputtering method, an inert gas such as Ar is used as a discharge gas. In both methods, an object to be etched is used as an electrode. On the other hand, unlike the reactive ion etching method and the reverse sputtering method, the plasma processing method is a method of simply exposing an etching target to a plasma atmosphere without using an etching target as an electrode.

The processing apparatus used for the plasma processing method is not particularly limited, but it is usually preferable to use a barrel-type plasma processing apparatus. In a barrel-type plasma processing apparatus, unlike a reactive ion etching apparatus or a sputter etching apparatus used for a reverse sputtering method, a sample to be etched is not disposed on an electrode, but is exposed to plasma while being electrically insulated from the surroundings. You. Specifically, for example, the counter electrode is arranged in a quartz chamber. In this apparatus, first, after inserting a sample to be etched into the chamber, the inside of the chamber is evacuated to, for example, 10 Pa or less.
Next, a discharge gas containing an oxidizing gas such as oxygen is introduced into the chamber, and the pressure in the chamber is maintained at about 100 Pa by adjusting the pumping speed of the vacuum pump. In this state, plasma is generated by applying high frequency power to the electrodes. By heating the sample to about 100 ° C. during the etching, the etching time can be reduced to ３ or less.
The high-frequency power used for plasma excitation is not limited to the normally used frequency of 13.56 MHz, but may be any frequency that can generate plasma from a relatively low frequency of about 100 kHz to a microwave of about 2.45 GHz. An equivalent etching effect can be obtained.

No proposal has been made to use a plasma processing method or a reactive ion etching method for elementary etching of an organic PTC thermistor. The plasma processing method has a slightly lower etching rate than the reactive ion etching method or the reverse sputtering method, but the plasma processing method does not directly apply a high voltage for plasma generation to the sample, so the apparatus configuration is simple. The fact that it is possible to simultaneously etch a large number of samples, that it is easy to simultaneously etch both sides of the sample, and that the continuous processing of a sheet-like sample in a roll-up manner is a structural aspect of the apparatus. It has advantages such as being easy. That is, the method using the plasma processing method is low cost,
Good productivity. On the other hand, the reactive ion etching method is preferable because it has excellent selectivity when etching a polymer as compared with the reverse sputtering method.

In the method using gas discharge plasma, depending on the composition of the polymer, it is possible to selectively remove the polymer on the surface of the element from tens of seconds to tens of minutes to a depth of about 20 μm at the maximum. It is possible.

UV irradiation and exposure to an ozone-containing atmosphere
By irradiating the thermistor body with the selective removal method utilizing at least one of the dew rays with ultraviolet light, the bonds between atoms in the polymer can be broken. If the ultraviolet irradiation is performed in an oxidizing atmosphere, the decomposed product can be oxidized and removed by a surrounding oxidizing gas. On the other hand, the polymer can also be removed by performing ultraviolet irradiation in an inert gas, followed by washing with water or etching. In addition,
The etching in this case may be performed using an organic solvent or the like.

Further, the polymer can be selectively removed by exposing the thermistor body to an atmosphere containing ozone having a strong oxidizing power to directly react the ozone with the polymer.

In addition, ultraviolet irradiation and exposure to an ozone-containing atmosphere can be used in combination. In the combined method, bonds between atoms in the polymer are cut by irradiation with ultraviolet rays, and the bonds are strongly oxidized and removed by ozone.

The oxidizing atmosphere used for the ultraviolet irradiation method is not particularly limited, and may be, for example, air. Also,
The ozone concentration in the ozone-containing atmosphere used in each of the above methods is not particularly limited, and may be appropriately determined so as to obtain a necessary removal rate.

In the method using ultraviolet irradiation and the method of exposing to an ozone-containing atmosphere, the etching rate is lower than that in the method using gas discharge plasma, but the cost is reduced because no vacuum device is used. It is also excellent in that a large area etching process can be performed. In addition, in the method using both the ultraviolet irradiation and the exposure to the ozone-containing atmosphere, an etching rate comparable to the method using gas plasma can be obtained. Specifically, for example, if a commercially available UV ozone cleaner is used, a maximum of 20 μm
Selective removal is possible to a certain depth. The UV ozone cleaner is a device that oxidizes oxygen in the air with ultraviolet rays at the same time as irradiating a sample with ultraviolet rays by an ultraviolet lamp, and reacts the generated ozone with the sample.

Selective Removal Method Utilizing Laser Light Irradiation of laser light to the thermistor body breaks intermolecular bonds of the polymer due to strong photochemical excitation of the laser light, and the polymer separates, decomposes, and scatters. By utilizing this, the polymer can be selectively removed from the element body surface. This method is generally called a laser ablation method, and is a type of photolytic removal processing. The etching rate is high for resins having relatively weak intermolecular bonds, and generally low for inorganic materials such as metals. It is excellent in selectivity when the polymer is selectively removed from the element body. Further, since there is almost no rise in the temperature of the element body during processing, high-quality processing is possible. Further, deep etching can be performed in a short time. In addition, a large area can be processed by scanning with a laser beam.

As a laser processing apparatus used in this method, an excimer laser processing apparatus is preferable. The excimer laser may be any of KrF, ArF, NeF, XeF and the like, and the same effect can be obtained in any case. The power of the excimer laser is not particularly limited, and may be appropriately determined depending on the combination of the polymer and the conductive particles, and is usually 0.1 to 6 J / cm ² as the energy density.
Degree, preferably about 0.5 to ⁴ J / cm ² .

The etching principle is different from that of the excimer laser, and the etching selectivity is inferior to the case of using the excimer laser.
Etching can also be performed with a laser or the like.

Selective Removal Method Using Sandblast By subjecting the surface of the thermistor body to sandblasting, the polymer near the surface of the body can be removed. However, this method is inferior in selectivity when selectively removing the polymer. Further, physical damage to the thermistor body and contamination with impurities may occur, which may cause deterioration of the thermistor characteristics. However, for example, Japanese Patent Application Laid-Open No. Hei 4-444
Unlike the wet etching method described in Japanese Patent Application Publication No. 01-301, there is no damage to the inside of the element body.

Electrode forming step After the polymer is selectively removed, an electrode is formed on the thermistor body surface.

The electrode may be a metal foil pressed or a metal layer formed by a vapor phase growth method such as sputtering or ion plating, but preferably includes a resin electrode layer.

The resin electrode layer has a structure in which conductive electrode material particles are dispersed in a resin.

The resin electrode layer has the same structure as the thermistor body in that it contains particles having conductivity. However, in the resin electrode layer, a resin or an amorphous resin having a lower crystallinity than the crystalline polymer used for the thermistor element is used, or the content of the electrode material particles is increased, or these are used in combination. Thus, the operation as the organic PTC thermistor is suppressed. With such a configuration, the resin electrode layer can be made to substantially exhibit no PTC characteristics.

The resin used for the resin electrode layer may be appropriately selected from those which do not substantially cause the PTC operation when the electrode material particles are dispersed as described above, and a resin having adhesiveness is particularly preferable. Specifically, for example, epoxy resin, phenol resin, urethane resin, silicone resin,
What is necessary is just to select from polyester, polyimide, acrylic resin, etc. Of these, epoxy resins are particularly preferred.

The electrode material particles are not particularly limited, and may be appropriately selected from the various conductive particles mentioned in the description of the thermistor body, but preferably metal particles are used. In addition, preferably, particles having the same composition as the conductive particles contained in the element body, for example, metal particles are used as the electrode material particles if the conductive particles are metal particles, and more preferably particles having the same composition are used. The shape of the electrode material particles is not particularly limited, and may be any of flakes, spheres, irregular shapes, or those having the above-described spike-shaped protrusions, but in order to increase the conductivity of the resin electrode layer, It is preferable to use a flake-like or spike-like protrusion.

The preferred average particle size of the electrode material particles varies depending on the type, shape, diameter measuring method and the like, but is usually about 0.01 to 10 μm.

The ratio (volume ratio) of the electrode material particles in the resin electrode layer is appropriately determined so that the conductivity required for the resin electrode layer is obtained and the PTC characteristics are not substantially exhibited during operation. Good. The preferred ratio of the electrode material particles {electrode material particles / (resin + electrode material particles)} varies depending on various conditions such as the shape of the electrode material particles, but is preferably from 60 to 60%.
It is 95% by volume, more preferably 70 to 90% by volume.
If the ratio of the electrode material particles is too low, the resistance value of the resin electrode layer increases, and PTC characteristics may be exhibited depending on the type of the resin to be combined. On the other hand, if the ratio of the electrode material particles is too high, uniform dispersion becomes difficult when kneading with the resin, and the adhesive force and workability decrease.

The paste or paint for forming the resin electrode layer may be prepared by kneading the above-mentioned resin and electrode material particles, and may be prepared from a commercially available conductive adhesive, conductive paint, conductive paste, or the like. You may choose.

When the resin electrode layer is formed on the surface of the thermistor body where the conductive particles are exposed by selective removal of the polymer, the conductive particles are embedded in the resin electrode layer, so that the adhesive strength of the resin electrode layer is extremely high. Get higher. In particular, when a conductive particle having a spike-shaped protrusion is used,
Adhesive strength is significantly improved.

The electrode may be composed of only the resin electrode layer, but preferably, a metal electrode layer is provided on the resin electrode layer to have a constitution as shown in FIG. In the figure, a pair of resin electrode layers 31, 31 are provided in contact with the surface of the thermistor body 2, and the metal electrode layers 32,
32 are provided. In this configuration, the electrode 3 is composed of the resin electrode layer 31 and the metal electrode layer 32.

When an electrode is composed of only the resin electrode layer,
Since the resin electrode layer has a large in-plane resistance, for example, when a large current is applied, local current concentration occurs in the thermistor body, causing abnormal heat generation, local damage, and reduced reliability during repeated operation. There is. Further, the resin electrode layer has low mechanical strength. Also, when connecting the electrode and the external circuit,
In some cases, it is difficult to connect a lead wire with an electrode composed of only a resin electrode layer. On the other hand, if the metal electrode layer is laminated on the resin electrode layer, the in-plane resistance of the entire electrode will be low, it will be mechanically strong, and the problem of lead wire connection will be solved. I do.

The method for forming the metal electrode layer is not particularly limited.
Any of a method of thermocompression bonding a metal foil and a method of forming a metal layer by a vapor phase growth method such as sputtering or ion plating may be used. When a material having adhesive properties such as a conductive adhesive is used for the resin electrode layer, the metal foil can be firmly bonded. Further, by providing the resin electrode layer, the plating method can be used. At the time of plating, since the resin electrode layer is interposed between the thermistor body and the plating solution, the plating solution is prevented from directly touching the body, and the body is not affected by the plating solution. Since irregularities are formed on the surface of the thermistor body by selective removal of the polymer, when a plating layer is formed directly on the surface of the body, the surface of the plating layer has a shape in which the irregularities of the body surface are enlarged as described above. Will be. However, even if there are irregularities on the surface of the element body, the surface of the resin electrode layer formed thereon becomes flat, so that a smooth plating layer can be formed. For this reason, it is possible to solve the problem of the abnormal growth of the plating electrode due to the roughening of the plating electrode forming surface, the increase in the in-plane resistance, the decrease in the mechanical strength, and the like, which have conventionally been problems. In addition,
In order to prevent the intrusion of the plating solution from the element body side surface (the surface on which the resin electrode layer is not formed), a protective coating layer may be formed on the element body side surface.

The lower the resistance of the electrode, the better.
It is preferable that the resistance value hardly increases in a temperature range in which the C thermistor operates. That is, PT
When operating as a C thermistor, it is preferable that the resistance of the electrode be significantly lower than the resistance of the thermistor body. Specifically, at the PTC operating temperature, the resistance value of the electrode may be 1/100 or less of the resistance value of the thermistor body. In addition, during non-operation (25 ° C.), the resistance value of the electrode is preferably equal to or less than the resistance value of the thermistor body,
It is more preferably 1/10 or less. Here, the resistance value at PTC operating temperatures _{say, (R max + R 25)} / 2
Means R _max is the maximum resistance value when the temperature is raised, and R ₂₅ is the resistance value at 25 ° C. Further, the resistance value of the electrode as referred to herein means the resistance value of the entire electrode. For example, when the electrode is formed of a resin electrode layer and a metal electrode layer, the resin electrode layer alone must satisfy the above conditions There is no.

[0066]

Example 1 An organic PTC thermistor sample was prepared according to the procedure shown below for Sample No. 101 . Preparation of the thermistor body A polyethylene oxide (melting point 67 ° C.) having a weight average molecular weight Mw of 430 to 4.8 million was prepared as a polymer, and filamentous nickel powder (INCO Type 255 nickel powder manufactured by Inco Corporation) was used as conductive particles. ) Was prepared. The filament-like powder is composed of particles formed by connecting particles having spike-like projections. The particles having spike-like projections have an average particle size of 2.2 to 2.8 μm and an apparent density of 0.5 to 0.2 μm.
It is 65 g / cm ³ and the specific surface area is 0.68 m ² / g.

Next, conductive particles were added to the polymer and kneaded in a mill at 80 ° C. for 5 minutes. The obtained kneaded material was molded by a press molding machine to obtain a sheet-shaped thermistor body having a thickness of 1 mm. The ratio of the conductive particles in the thermistor body was 24% by volume.

Selective Removal Step The thermistor body was irradiated with ultraviolet rays in an ozone-containing atmosphere using a UV ozone cleaner (VUM-3073-13-00, manufactured by Oak Manufacturing Co., Ltd.). This UV ozone cleaner is provided with four 40 W low-pressure mercury lamps, and has an effective irradiation area of 20 cm × 20 cm. The polymer was selectively removed from the thermistor body surface to a depth of about 10 μm by ultraviolet irradiation for 5 minutes and exposure to an ozone-containing atmosphere.

FIGS. 3 and 4 show scanning electron microscope photographs of the thermistor body surface before and after the selective removal, respectively. Since the electron beam transmits through the polymer to some extent, the brightness of the polymer is low and the brightness of the conductive particles is high. In FIG. 3 before the selective removal treatment, it can be clearly seen that the conductive particles near the element body surface are covered with a thin film-like polymer. FIG. 4 after the selective removal process clearly shows that the conductive particles are exposed.

Further, the conductivity of the element body surface before and after the selective removal treatment was evaluated using the current application mode of the atomic force microscope. FIG. 5 shows an output image of the surface before the selective removal processing, and FIG.
Shows output images after the selective removal processing. FIG. 5 shows that the surface of the element body before the selective removal treatment was almost insulated, and FIG. 6 shows that the conductivity of the surface was significantly improved by the selective removal treatment.

Electrode Forming Step Spherical Ag particles having a diameter of 0.1 to 5 μm were prepared as electrode material particles. These electrode material particles and an acrylic resin were kneaded to prepare a conductive paint. This conductive paint is applied to both sides of the thermistor body and has a thickness of 100 μm.
Of the resin electrode layer. The ratio of the electrode material particles in the resin electrode layer was 80% by volume.

Then, a 16 μm thick Ni plating layer was formed as a metal electrode layer on the surface of the resin electrode layer. As the plating bath, a sulfamic acid bath having a pH of 4.5 and a liquid temperature of 50 ° C. was used, the current density was 5 A / cm ² , and the plating time was 20 minutes.

After forming the metal electrode layer, a disk having a diameter of 10 mm was punched out to obtain an organic PTC thermistor sample.

Sample No. 102 Sample No. 101 except that no metal electrode layer was formed
In the same manner as in the above, Sample No. 102 was produced.

Sample No. 103 (Comparative Example) Sample No. 1 except that the polymer was not selectively removed.
Sample No. 103 was produced in the same manner as Sample No. 01.

For each of the above samples, at 25 ° C. and 8 ° C.
The resistance value (initial resistance value) was measured at 5 ° C. Next, after repeating a cycle test in which heating and cooling were repeated between room temperature and 120 ° C. 1000 times, a resistance value (resistance value after the cycle test) was measured in the same manner. The resistance value was measured using a four-terminal method. Table 1 shows the results.

[0077]

[Table 1]

Table 1 clearly shows the effect of the present invention.
Comparing the initial resistance value at 25 ° C. and the resistance value after the cycle test, Sample Nos. 101 and 102 in which the polymer was selectively removed from the thermistor body surface were compared with Sample No. 103 in which the selective removal was not performed. It is significantly lower. In each sample, a sufficiently high resistance value was obtained at 85 ° C. As described above, the organic PTC thermistor manufactured by the method of the present invention has a sufficiently low initial resistance value, and the fluctuation of the resistance value due to the repetition of the PTC operation is so small as to be practically negligible.

The above-mentioned heating / cooling cycle is for heating the entire sample. Even when heating was performed by energizing the sample, the same result as in Table 1 was obtained after 1000 repetitions. .

With respect to the electrodes used for each of the above samples,
Resistance values in the range of 5 to 120 ° C were determined. Since the resistance value of the electrode alone cannot be directly measured, first, the conductive paint used for forming the resin electrode layer was applied on an insulating substrate, and the specific resistance was measured using a four-probe probe method. As a result, the specific resistance of the conductive paint is 1 × 10 ⁻³ to 1 × 10 ^3
−2 Ωcm, and no change in specific resistance was observed between room temperature and 120 ° C. When the specific resistance of the Ni plating layer formed in the same manner as the above-mentioned metal electrode layer was measured, it was about 1 × 10 ⁻⁵ Ωcm,
No change in specific resistance was observed up to 0 ° C. From these results, the electrode resistance value in this example was 0.1 m
It can be seen that it is estimated to be Ω, and the electrode resistance does not show temperature dependence. From the electrode resistance value and the sample resistance values shown in Table 1, the resistance value R ₂₅ at 25 ° C. and the PTC
It can be seen that the resistance {(R _max + R ₂₅ ) / 2} at the operating temperature is sufficiently lower for the electrode than for the thermistor body.

A sample was prepared in the same manner as in Sample No. 101 except that the resin electrode layer was not provided. However, when the metal electrode layer was formed by plating, the weight of the element in a plating bath was reduced. Since the coalescence swelled and partially dissolved, it was impossible to form a metal electrode layer.

Example 2 Preparation of Sample No. 201 Thermistor Element Nylon 12 having Mw of 30,000 as a polymer (melting point: 180 ° C.)
And a thermistor body was produced in the same manner as in Example 1 except that the kneading temperature was 190 ° C.

Selective Removal Step This thermistor body was set in a reactive ion etching type ashing apparatus and etched. O ₂ was used as a discharge gas, the discharge pressure was 20 Pa, the power density was 0.25 W / cm ² , and the discharge time was 2 minutes. As a result, the polymer from the thermistor body surface to a depth of about 10 μm was selectively removed.

Electrode Forming Step Ni particles having spike-like projections (average particle size of 2.2 to 2.8 μm) were prepared as electrode material particles. The electrode material particles and the epoxy resin were kneaded to prepare a conductive adhesive. This conductive adhesive was applied to both surfaces of the thermistor body to form a resin electrode layer having a thickness of 100 μm. The ratio of the electrode material particles in the resin electrode layer was 80% by volume.

Next, a 30 μm-thick Ni foil was bonded as a metal electrode layer to the surface of the resin electrode layer.

After bonding of the metal electrode layer, a disk having a diameter of 10 mm was punched out to obtain an organic PTC thermistor sample.

Sample No. 202 (Comparative Example) Sample No. 2 except that the polymer was not selectively removed and the metal electrode layer was thermocompressed to the element without providing the resin electrode layer.
Sample No. 202 was produced in the same manner as in Sample No. 01.

Sample No. 203 No resin electrode layer was provided, and the sample was used as a metal electrode layer.
Sample No. 203 was prepared in the same manner as Sample No. 201 except that the same Ni plating layer as that of No. 101 was formed.

For each of the above samples, 25 ° C. and 1
At 90 ° C., the resistance value (initial resistance value) was measured. Next, after repeating a cycle test in which heating and cooling were repeated between room temperature and 200 ° C. 1000 times, a resistance value (resistance value after the cycle test) was measured in the same manner. The resistance value was measured using a four-terminal method. Table 2 shows the results.

[0090]

[Table 2]

Table 2 clearly shows the effect of the present invention.
That is, comparing the initial resistance value at 25 ° C. and the resistance value after the cycle test respectively, Sample No. 201 and No. 203 where the polymer was selectively removed were compared with Sample No. 202 where the selective removal was not performed. It is significantly lower. In addition, the increase in the resistance value by the cycle test was the same as in Sample No. 201 in which the resin electrode layer was provided, but in Sample No.
It is less than 203. This is considered to be due to stress absorption by the resin electrode layer. Sample No.
It is considered that the increase in the resistance value by the cycle test of 203 also relates to the deterioration due to the penetration of the plating solution. in this way,
The organic PTC thermistor manufactured by the method of the present invention has a sufficiently low initial resistance value and a resistance value variation due to repetition of the PTC operation is practically negligible.
Extremely reliable.

The heating / cooling cycle described above heats the entire sample. Even when heating was performed by applying a current to the sample, the same result as in Table 2 was obtained after 1000 repetitions. .

The specific resistance of the electrodes used for each sample in Table 2 was
When measured in the same manner as in Example 1, the same as in Example 1 was obtained.
The electrode resistance is estimated to be 0.1 mΩ, and the electrode resistance is
Showed no temperature dependence. This electrode resistance
From the values and the resistance values of the samples shown in Table 2, at 25 ° C
Resistance R of_{twenty five}And the resistance 温度 (R
_max+ R_{twenty five}) / 2｝ indicates that the electrode is a thermistor body
It can be seen that this is sufficiently lower than.

Example 3 The thermistor element used for Sample No. 101 was etched using a reactive ion etching type ashing apparatus. The discharge gas used was O ₂ or Ar, the discharge pressure was 20 Pa, the power density was 0.25 W / cm ² , and the discharge time was 1 minute. As a result, the polymer was selectively removed from the thermistor body surface to a depth of about 5 μm.
FIG. 7 shows a scanning electron micrograph of the thermistor body surface when the reactive ion etching method using O ₂ is used.
FIG. 8 shows a scanning electron micrograph of the thermistor body surface when the reactive ion etching method using Ar is used. As described above, in FIG. 3 before the selective removal treatment, it can be clearly seen that the conductive particles near the element body surface are covered with a thin film-like polymer. 7 and 8 after the selective removal process, it can be clearly seen that the conductive particles are exposed. Using an atomic force microscope, the conductivity of the element body surface before and after the selective removal treatment was evaluated. did it.

An organic PTC thermistor was prepared in the same manner as in Sample No. 101 except for the selective removal method, and the same measurement as in Example 1 was performed. As a result, a result equivalent to that of Sample No. 101 was obtained.

Example 4 Preparation of a Thermistor Element Polyvinylidene fluoride (PVDF: Kayner 71 manufactured by Elf Atochem North America, Inc., USA)
1) was prepared. A silane coupling agent (KBC100 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by weight of the polymer.
3) was added in an amount of 10 parts by weight.
5-dimethyl-2,5-di (t-butylperoxin)
Hexin-3 was added in an amount of 1 part by weight, and heated to 200 ° C. to obtain a graft resin using a twin screw extruder. Next, WC particles having an average particle diameter of 0.65 μm (WC-F manufactured by Nippon Shinkin Co., Ltd.) were mixed with the graft resin so as to be 20% by volume of the whole, and kneaded for 1 hour at 200 ° C. did.
Thereafter, a thermistor body was obtained in the same manner as in Sample No. 101 of Example 1.

Selective Removal Step The thermistor body was set in a reactive ion etching type ashing apparatus and etched. O ₂ was used as the discharge gas, the discharge pressure was 20 Pa, the power density was 0.25 W / cm ² , and the discharge time was 1 minute. As a result, the polymer was selectively removed from the thermistor body surface to a depth of about 5 μm. Note that Ar gas is used as a discharge gas.
When etching was used, the etching rate was slightly reduced, but O ₂
The polymer was selectively removed almost in the same manner as in the case of using.

FIG. 9 is a scanning electron micrograph of the surface of the thermistor element before selective removal, and FIG. 10 is a scanning electron micrograph of the surface of the thermistor element after selective removal using O ₂ as a discharge gas. FIG. 11 shows a scanning electron micrograph of the sample after the selective removal using Ar as the working gas.
In FIG. 9 before the selective removal treatment, it can be clearly seen that the conductive particles near the element body surface are covered with a thin film-like polymer.
Then, in FIGS. 10 and 11 after the selective removal processing, it can be clearly seen that the conductive particles are exposed. In addition, as a result of evaluating the conductivity of the element body surface before and after the selective removal treatment using an atomic force microscope, it was confirmed that the conductivity was substantially improved before the selective removal treatment, and the conductivity was significantly improved by the selective removal treatment. did it.

Electrode Forming Step The electrode was formed in the same manner as in Sample No. 201.

The organic PTC thermistor sample thus prepared was measured in the same manner as in Example 1. The resistance R ₂₅ at 25 ° C. was 9.5Ω, and the resistance R ₁₂₀ at 120 ° C. was ₁₃₀ MΩ. there were. For comparison where, to prepare a sample directly Ni foil was heat pressed in the thermistor element, was also subjected to measurement of the resistance values for this, R ₂₅
Is 20 [Omega, R ₁₂₀ was 150Emuomega. For these samples, after repeating a cycle test of repeating heating and cooling between room temperature and 140 ° C. 1000 times, the resistance values were measured in the same manner. In the samples of the present invention, R ₂₅ and R ₁₂₀ were both the initial values. While the rate of change was kept at + 50% or less, the electrode was completely peeled off in the comparative sample, making it impossible to evaluate the characteristics.

Example 5 A thermistor element used for Sample No. 101 was applied to a barrel-type plasma processing apparatus (DE manufactured by Plasma System Co., Ltd.).
(S-106-254AEN) using the following procedure.
In this apparatus, a counter electrode is arranged in a cylindrical quartz chamber having a diameter of 25 cm and a length of 40 cm, and the sample to be etched is not arranged on the electrode as described above. First, after inserting the thermistor body into the chamber, the inside of the chamber was evacuated to 10 Pa or less. Then O
_2, and the pressure inside the chamber was kept at 100 Pa by adjusting the pumping speed of the vacuum pump. In this state, plasma was generated by applying high-frequency power of 13.56 MHz to 400 W to the electrodes, and the thermistor body was exposed to the plasma for 15 minutes. As a result, the polymer from the thermistor body surface to a depth of about 10 μm was selectively removed.

An organic PTC thermistor was manufactured in the same manner as in Sample No. 101 except that the thermistor element thus selectively removed was used, and the same measurement as in Example 1 was performed. A result equivalent to 101 was obtained.

Example 6 The thermistor element used for Sample No. 101 was etched by a laser ablation method using a KrF excimer laser having a wavelength of 248 nm. The energy density was ² J / cm ² , and the pulse irradiation frequency was 10 times. As a result, the polymer from the thermistor body surface to a depth of about 10 μm was selectively removed.

An organic PTC thermistor was prepared in the same manner as in Sample No. 101 except that the thermistor element thus selectively removed was used, and the same measurement as in Example 1 was performed. A result equivalent to 101 was obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration example of an organic PTC thermistor.

FIG. 2 is a cross-sectional view illustrating a configuration example of an organic PTC thermistor.

FIG. 3 is a drawing substitute photograph showing a particle structure, and is a scanning electron micrograph of the thermistor body surface before a polymer (polyethylene oxide) is selectively removed.

FIG. 4 is a drawing substitute photograph showing a particle structure, and is a scanning electron micrograph of the thermistor body surface after a polymer (polyethylene oxide) is selectively removed by a UV ozone cleaner.

FIG. 5 is a drawing substitute photograph showing a particle structure, and is an output image of the thermistor element body surface before selective removal of a polymer, which is taken by an atomic force microscope.

FIG. 6 is a drawing substitute photograph showing a particle structure, and is an output image of the thermistor element body surface after selective removal of a polymer, which is taken by an atomic force microscope.

FIG. 7 is a drawing substitute photograph showing a particle structure, and is a scanning electron micrograph of a thermistor element surface after a polymer (polyethylene oxide) is selectively removed by reactive ion etching using O _2. .

FIG. 8 is a drawing substitute photograph showing a particle structure, and is a scanning electron micrograph of the thermistor body surface after a polymer (polyethylene oxide) is selectively removed by reactive ion etching using Ar.

FIG. 9 is a drawing-substitute photograph showing the particle structure, and is a scanning electron micrograph of the thermistor element surface before the polymer (polyvinylidene fluoride) is selectively removed.

FIG. 10 is a drawing substitute photograph showing a particle structure, and is a scanning electron microscope photograph of the surface of a thermistor element body after a polymer (polyvinylidene fluoride) is selectively removed by reactive ion etching using O _2. is there.

FIG. 11 is a drawing substitute photograph showing a particle structure, and is a scanning electron micrograph of the thermistor body surface after a polymer (polyvinylidene fluoride) is selectively removed by reactive ion etching using Ar. .

[Description of Signs] 2 Thermistor element 3 Electrode 31 Resin electrode layer 32 Metal electrode layer

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[Procedure amendment]

[Submission date] April 9, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

Claims (13)

[Claims] 1. A method for producing an organic PTC thermistor having a thermistor element having a structure in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by a plasma treatment method to expose conductive particles to the surface of the thermistor body; and an electrode forming step of forming an electrode. A method for producing an organic PTC thermistor. 2. A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by reactive ion etching to expose the conductive particles to the thermistor body surface;
An electrode forming step of forming an electrode. 3. A method for producing an organic PTC thermistor having a thermistor element having a structure in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A step of selectively removing the crystalline polymer from the surface of the thermistor body by irradiating ultraviolet rays to expose conductive particles to the surface of the thermistor body; and an electrode forming step of forming an electrode. A method for producing an organic PTC thermistor comprising: 4. A method for producing an organic PTC thermistor having a thermistor element having a structure in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by irradiating ultraviolet rays and exposing to an ozone-containing atmosphere to expose the conductive particles to the thermistor body surface; An electrode forming step of forming an electrode. 5. A method for producing an organic PTC thermistor having a thermistor body having a structure in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor body. A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by exposing to an ozone-containing atmosphere to expose conductive particles to the thermistor body surface; and forming an electrode. Organic PT having a forming step
Manufacturing method of C thermistor. 6. A method for producing an organic PTC thermistor having a thermistor element having a configuration in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A selective removal step of selectively removing the crystalline polymer from the surface of the thermistor body by irradiating a laser beam to expose the conductive particles to the thermistor body surface;
An electrode forming step of forming an electrode. 7. An electrode including a resin electrode layer having a configuration in which conductive electrode material particles are dispersed in a resin in the electrode forming step, and when operating as a PTC thermistor, the resistance of the electrode is reduced. The method for producing an organic PTC thermistor according to any one of claims 1 to 6, wherein an organic PTC thermistor having a resistance of 1/100 or less of said thermistor body is produced. 8. A method for producing an organic PTC thermistor having a thermistor element having a structure in which conductive particles are dispersed in a crystalline polymer and an electrode provided on the surface of the thermistor element. A selective removal step of selectively removing the crystalline high molecular polymer from the surface of the thermistor body to expose conductive particles to the surface of the thermistor body; and a structure in which conductive electrode material particles are dispersed in a resin. An electrode forming step of forming an electrode including the resin electrode layer of the above, wherein when operating as a PTC thermistor, an organic PTC thermistor having a resistance value of 1/100 or less of a resistance value of the thermistor element body A method for producing an organic PTC thermistor to be produced. 9. The method of manufacturing an organic PTC thermistor according to claim 8, wherein said selective removing step uses a reverse sputtering method. 10. The method for producing an organic PTC thermistor according to claim 8, wherein a sand blast method is used in said selective removing step. 11. The method according to claim 7, wherein the electrode includes a metal electrode layer, and the metal electrode layer is formed on the resin electrode layer.
The method for producing an organic PTC thermistor according to any one of the above. 12. The method for manufacturing an organic PTC thermistor according to claim 11, wherein said metal electrode layer is formed by plating. 13. The method for manufacturing an organic PTC thermistor according to claim 11, wherein said resin electrode layer has adhesiveness, and said metal electrode layer is a metal foil.