JP2013053030A - Plate-like ruthenium oxide powder, method for producing the same, and thick film resistor composition using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, as a conductive component of a thick film resistor composition, plate-like ruthenium oxide powder having a strong structure of a baked film even when a compounding ratio to a glass bonding agent is heightened, and having a small resistance value change even when a load of static electricity or surge current is put thereon, and to provide a method for producing the same, and a thick film resistor composition using the same.SOLUTION: This invention relates to a method for producing plate-like ruthenium oxide powder including a process for thermally treating a mixture of a ruthenium compound and a barium compound under an acid atmosphere at a temperature of ≥400°C, to thereby synthesize a plate-like composite oxide of ruthenium and barium; then, a process for, after mixing boron oxide or boric acid with the obtained plate-like composite oxide, performing heat treatment at a temperature of ≥500°C, to thereby produce a plate-like composite oxide in a melt of plate-like ruthenium oxide powder, boron oxide and barium oxide; and a process for adding a solvent into the obtained melt to dissolve the boron oxide and barium oxide, to thereby recover the plate-like ruthenium oxide powder.

Description

  The present invention relates to a plate-like ruthenium oxide powder, a method for producing the same, and a thick film resistor composition using the same. As a conductive component of the thick film resistor composition, firing is performed even when the compounding ratio is increased with respect to the glass binder. The present invention relates to a plate-like ruthenium oxide powder having a strong film structure and having a small resistance change even when static electricity or surge current is applied, a method for producing the same, and a thick film resistance composition using the same.

Thick film resistors are widely used in chip resistors, thick film hybrid ICs, resistor networks, and the like. In recent years, the miniaturization of electronic components has progressed, and in chip resistors, the mainstream size used to be 1.6 mm long × 0.8 mm wide, but now it is 1.0 mm long × 0.5 mm wide. In recent years, the production amount of chip resistors having a length of 0.6 mm and a width of 0.3 mm is also increasing. Accordingly, the thickness of the thick film resistor is also changed from 0.5 mm length × 0.5 mm width to 0.3 mm length × 0.3 mm width, and further shifted to 0.2 mm × width 0.2 mm or less.
However, when the resistor size is reduced, the resistance value change due to an electrical load increases, and there is a concern about the reliability of the resistor. For this reason, consideration is generally given to reducing the rated power of a small resistor. However, static electricity, surge current, etc. cannot be reduced even with a small resistor. Therefore, there is a demand for a thick film resistor that has a small change in resistance value due to static electricity or surge current even if the size of the resistor is small.

  A thick film resistor composition, which is a material of the thick film resistor, is manufactured by dispersing a conductive component and a glass binder in an organic medium called a vehicle. Of these, the conductive component has the most important role of determining the electrical characteristics of the thick film resistor, and Ru oxide powder is widely used as the conductive component of the thick film resistor. The thick film resistor composition is printed on an insulating ceramic substrate and then fired to obtain a thick film resistor having a film structure in which conductive components are dispersed in an insulating matrix.

In general, in the case of a thick film resistor using only Ru oxide powder as a conductive component, a thick film resistor having a specific resistance value of 1 × 10 ⁻³ to 1 × 10 ⁴ Ω · cm can be formed.
In a thick film resistor having a specific resistance value of 1 × 10 ⁻² Ω · cm or more, the resistance value generally changes to negative due to static electricity or surge current. However, in the case of a thick film resistor smaller than 1 × 10 ⁻² Ω · cm, the resistance value may greatly change positively. This is expected to be caused by the structure of the thick film resistor in which the Ru oxide is a conductive component and the glass binder is an insulating component. Generally, in order to reduce the specific resistance value, it is necessary to increase the blending of the conductive component and reduce the blending of the insulating component. However, since the Ru oxide itself does not sinter, the thick film resistor containing a large amount of the conductive component is likely to have a brittle film structure, and fine cracks are likely to occur. For this reason, when a thick film resistor having a low specific resistance value is loaded with static electricity or a surge current, fine cracks spread and become large cracks, and the resistance value changes positively.

By the way, in a thick film resistance composition having a specific resistance value of 1 × 10 ⁻² Ω · cm or less, it is generally performed to add Ag and Pd as conductive components in order to lower the specific resistance value (Japanese Patent Laid-Open No. Hei 05- 90006: Patent Document 1). In such a thick film resistor in which Ag and Pd are added as conductive components, since the Ag and Pd are sintered, the fired film becomes strong and cracks and the like are difficult to enter. However, in the material system containing Ag and Pd as conductive components, there is a problem that the resistance value largely changes negatively by a surge current.
For this reason, in the thick film resistor having a specific resistance value of 1 × 10 ⁻² Ω · cm or more, in order to form a thick film resistor having a small resistance value change due to static electricity or surge current, Although the compounding of the Ru oxide is increased, it is necessary to form a fired film having a strong film structure and hardly cracking after firing.

Conventionally, as the ruthenium oxide powder used as the conductive component of the thick film resistance composition, generally 1 × 10 ⁻⁸ m to 3 × 10 ⁻⁷ m of granular material is used. Such granular ruthenium oxide is obtained by heat-treating a hydrated oxide obtained by reducing an alkali oxide of Ru with a neutralization reaction or an organic substance, or a hydrated oxide obtained by neutralizing a Ru chloride aqueous solution in an oxidizing atmosphere. (Japanese Patent Laid-Open No. 06-345441: Patent Document 2).
Ruthenium oxide does not sinter and remains a powder even when heat-treated at a high temperature of 500 ° C. or higher in an oxidizing atmosphere. Since ruthenium oxide is not sintered, the film structure is maintained by being hardened by a glass binder that softens during the firing process of preparing the thick film resistor. Therefore, a certain amount of glass binder is required to solidify fine non-sintered ruthenium oxide and maintain the film structure. However, if the compounding amount of the glass binder is increased, the specific resistance value of the thick film resistor is increased. It becomes high and it is difficult to obtain a low resistance value. Conversely, in order to reduce the amount of the glass binder, a ruthenium oxide powder having a large particle diameter may be used, but the number of contact points between the ruthenium oxides which are conductive components is reduced, and a low resistance value can be obtained even in this case. Absent.

Japanese Patent Laid-Open No. 05-90006 Japanese Patent Laid-Open No. 06-345441

  In view of the problems of the conventional method, the present invention has a strong structure of the fired film and is loaded with static electricity and surge current even when the compounding ratio is increased with respect to the glass binder as a conductive component of the thick film resistor composition. It is an object of the present invention to provide a plate-like ruthenium oxide powder having a small change in resistance value, a method for producing the same, and a thick film resistor composition using the same.

  As a result of intensive studies to solve the above-described conventional problems, the present inventors synthesized a complex oxide of ruthenium and barium in the form of a plate, and then mixed this with boron oxide and heat-treated. The ruthenium oxide powder maintaining the shape of the plate-like composite oxide of ruthenium and barium was found to be dispersed in the melt of boron oxide and barium oxide, and the plate-like shape separated from the melt by a solvent. Since the ruthenium oxide powder forms a resistor having a low specific resistance value, it was confirmed that the ruthenium oxide powder was useful as a conductive component of the thick film resistor composition, and the present invention was completed.

  That is, according to the first invention of the present invention, a step of synthesizing a plate-shaped composite oxide of ruthenium and barium by heat-treating a mixture of a ruthenium compound and a barium compound at an oxidizing atmosphere and a temperature of 400 ° C. or higher, Then, boron oxide or boric acid is mixed with the obtained plate-like composite oxide, and then heat treatment is performed at a temperature of 500 ° C. or more to melt the plate-like composite oxide into plate-like ruthenium oxide powder, boron oxide, and barium oxide. Production of a plate-like ruthenium oxide powder characterized by comprising a step of forming in a product, a step of adding a solvent to the resulting melt, and dissolving the boron oxide and barium oxide to recover the plate-like ruthenium oxide powder A method is provided.

According to a second aspect of the present invention, in the first aspect, the ruthenium compound is a Ru oxide that is wet-synthesized from a solution containing Ru. A method for producing ruthenium oxide powder is provided.
According to a third aspect of the present invention, in the first aspect, the barium compound is at least one selected from barium oxide, barium carbonate, barium nitrate, barium chloride, or barium sulfate. A method for producing a plate-like ruthenium oxide powder is provided.
According to the fourth aspect of the present invention, in the first aspect, the mixing ratio of the ruthenium compound and the barium compound is 0.8: 1.2 to 1.2: 0. A method for producing a plate-like ruthenium oxide powder is provided.
On the other hand, according to the fifth invention of the present invention, in the first invention, in the step of synthesizing the plate-like composite oxide, the heat treatment temperature of the mixture is 400 to 1000 ° C. A method for producing a powder is provided.
According to the sixth invention of the present invention, in the first invention, boron oxide or boric acid is 20 parts by weight or more with respect to 100 parts by weight of the plate-like composite oxide in terms of boron oxide. A method for producing a plate-like ruthenium oxide powder is provided.
According to a seventh aspect of the present invention, in the first aspect, in the step of melting the plate-shaped composite oxide, the heat treatment temperature is 500 to 1000 ° C. A manufacturing method is provided.
According to the eighth invention of the present invention, in the first invention, the boron oxide or boric acid is further mixed with a compound containing at least one selected from Mn, Nb, Ta, Ti, or Sn. By performing the heat treatment, a plate-like ruthenium oxide powder manufacturing method is provided, in which a plate-like ruthenium oxide powder in which Mn, Nb, Ta, Ti, or Sn element is dissolved is obtained.
According to a ninth aspect of the present invention, in the first aspect, the solvent added in the step of recovering the plate-like ruthenium oxide powder is an aqueous solution of a mineral acid or an organic acid. A method for producing plate-like ruthenium oxide powder is provided.
Furthermore, according to the tenth invention of the present invention, the major axis obtained by the production method of the first to ninth inventions is 1 × 10 ^{−6 to} 5 × 10 ⁻⁶ m, and the thickness is 1.5 ×. A plate-like ruthenium oxide powder that is 10 ^{−7 to} 5 × 10 ⁻⁷ m is provided.

On the other hand, according to the eleventh aspect of the present invention, there is provided a thick film resistor composition obtained by blending glass powder with the plate-like ruthenium oxide powder of the tenth aspect.
According to the twelfth aspect of the present invention, there is provided a thick film resistance composition obtained by blending the plate-like ruthenium oxide powder of the tenth aspect with a thermosetting resin and / or a thermoplastic resin.

According to the method of the present invention, a plate-like composite oxide of ruthenium and barium is formed, and the composite oxide is decomposed in its shape to synthesize a plate-like ruthenium oxide powder. A plate-like ruthenium oxide powder, which was difficult to manufacture by the technique, can be easily manufactured. The particle size of the ruthenium-barium plate-like composite oxide can be changed depending on the type of ruthenium raw material or barium raw material and the heat treatment conditions, and the size of the finally obtained plate-like ruthenium oxide can also be changed.
Furthermore, according to the present invention, by using this plate-like ruthenium oxide powder, a thick film resistor having no defects such as cracks can be formed even if the proportion of the conductive material is very high. Further, a resin-based thick film resistor having a low resistance value can be formed by mixing the plate-like ruthenium oxide powder with a thermosetting resin or a thermoplastic resin.

It is the photograph which observed an example of the plate-like ruthenium oxide powder of this invention with TEM (transmission electron microscope). It is the photograph which observed an example of the plate-like ruthenium oxide powder of this invention with TEM (transmission electron microscope). It is the photograph which observed an example of the plate-like ruthenium oxide powder of this invention with TEM (transmission electron microscope).

  Hereinafter, the plate-like ruthenium oxide powder of the present invention and the production method thereof will be described.

1. Production method of plate-like ruthenium oxide powder (1) Synthesis of plate-like composite oxide In the production method of the present invention, a ruthenium compound and a barium compound are mixed and heat-treated in an oxidizing atmosphere, whereby a plate-like ruthenium and barium plate is formed. A composite oxide is formed. Depending on the type of ruthenium raw material or barium raw material or the heat treatment method, the particle size of the plate-like composite oxide of ruthenium and barium changes, and the size of the finally obtained plate-like ruthenium oxide can also be changed.

The Ru compound used as a raw material in the present invention is not limited by its form, but it is possible to use a Ru oxide hydrate synthesized from a solution containing Ru or a Ru oxide obtained by baking this in an oxidizing atmosphere. it can. Typical examples of the Ru solution and synthesis method for synthesizing a hydrate of Ru oxide include a method of adding ethanol to a K ₂ RuO ₄ aqueous solution and a method of neutralizing a RuCl ₃ aqueous solution with KOH or the like. It is done. In the present invention, a Ru oxide obtained by roasting a Ru oxide hydrate in an oxidizing atmosphere is more preferable than a Ru oxide hydrate. This is because when a hydrate of Ru oxide is mixed with a barium compound and heat-treated in an oxidizing atmosphere, a large hexagonal plate-like crystal tends to be formed.
Examples of the Ba compound used as a raw material in the present invention include oxides, hydroxides, and carbonates. Ba oxide and Ba hydroxide are most suitable for the method of the present invention from the viewpoint of easy mixing with a Ru compound. Moreover, since Ba carbonate is also highly stable against the humidity of the raw material, it is particularly easy to use in an atmosphere with high humidity. Ba carbonate is relatively stable even at high temperatures, but when it is heat-treated in an oxidizing atmosphere together with a Ru compound, it decomposes at a temperature of 800 ° C. or lower to form a composite oxide with ruthenium.

The method for mixing the ruthenium raw material and the barium raw material is not particularly limited as long as both can be sufficiently mixed. Common methods are ball mills, rabies, shaker mixers and the like.
The ratio of the barium compound to the ruthenium compound is not particularly limited, but a molar ratio of ruthenium: barium is preferably in the range of 0.8: 1.2 to 1.2: 0.8. If it is out of this range, in addition to BaRuO ₃ , ruthenium oxide or a barium compound derived from the raw material may remain. The particle size and shape of the composite oxide of ruthenium and barium can be controlled by the starting material and the heat treatment temperature. It affects the particle size and shape. A more preferable range of the barium compound with respect to the ruthenium compound is 0.9: 1.1 to 1.1: 0.9 in terms of a ruthenium: barium molar ratio.

Next, the mixture of the ruthenium raw material and the barium raw material is heat-treated at a temperature of 400 ° C. or higher in an oxidizing atmosphere. Thereby, a complex oxide of ruthenium and barium is obtained. Here, the oxidizing atmosphere is a gas containing 10% by volume or more of oxygen, and for example, air can be used.
When the temperature of the heat treatment is lower than 400 ° C., the composite oxide of ruthenium and barium is not completely generated, which is not desirable. On the other hand, when the heat treatment temperature exceeds 1000 ° C., the particle size of the ruthenium-barium composite oxide becomes too large, or the ratio of volatilization of ruthenium as a hexavalent or octavalent oxide increases, which is not preferable. Therefore, a preferable heat treatment temperature is 500 to 900 ° C. The heat treatment time is 15 minutes or more, preferably 30 to 120 minutes, depending on the heat treatment temperature.

(2) Decomposition of composite oxide The composite oxide of ruthenium and barium obtained in this way is revealed to be a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic> from the X-ray diffraction pattern. The complex oxide of ruthenium and barium has conductivity, but the specific resistance value is an order of magnitude higher than that of ruthenium oxide, and the stability of the resistance value is inferior when a thick film resistor is formed. Therefore, in the present invention, ruthenium and barium composite oxide is mixed with boron oxide and heat-treated to decompose the ruthenium and barium composite oxide to form ruthenium oxide and a melt composed of barium oxide and boron oxide. To do.

Instead of boron oxide, boric acid or the like that becomes boron oxide during heat treatment may be used. Here, the amount of boron oxide to be mixed is such that boron oxide or boric acid is boron oxide with respect to 100 parts by weight of the Ru and Ba plate-like composite oxide synthesized by mixing a ruthenium compound and a barium compound and heat-treating in an oxidizing atmosphere. It needs to be 20 parts by weight or more in terms of. When the amount of boron oxide or boric acid is less than 20 parts by weight relative to the composite oxide of Ru and Ba, the decomposition of the composite oxide of Ru and Ba may be incomplete and remain. On the other hand, the larger the amount of boron oxide or boric acid, the more effective, but the economic merit is lost when it exceeds 200 parts by weight in terms of boron oxide. A more preferred amount of boron oxide or boric acid is 30 to 150 parts by weight.
The method of mixing boron oxide into the composite oxide of ruthenium and barium is not particularly limited as long as both can be mixed sufficiently. Common methods are ball mills, rabies, shaker mixers and the like. When this ruthenium and barium composite oxide is mixed with boron oxide, a compound containing one or more selected from Mn, Nb, Ta, Ti, or Sn can be mixed at the same time.

In this step, heat treatment is performed in an oxidizing atmosphere and at a temperature of 500 ° C. or higher. Here, the oxidizing atmosphere is a gas containing 10% by volume or more of oxygen, and for example, air can be used. When the temperature is lower than 500 ° C., the ruthenium-barium composite oxide is not completely decomposed. Further, when the temperature exceeds 1000 ° C., the rate of volatilization of ruthenium as a hexavalent or octavalent oxide increases, which is not preferable. The heat treatment time is 15 minutes or more although it depends on the heat treatment temperature. Therefore, a preferable heat treatment temperature is 600 to 1000 ° C. The heat treatment time is 15 minutes or more, preferably 30 to 120 minutes, depending on the heat treatment temperature.
When the heat treatment is performed, the composite oxide of ruthenium and barium is decomposed to become a glass composed of ruthenium oxide and barium oxide and boron oxide. Further, when the composite oxide of ruthenium and barium is a mixture of a compound selected from Mn, Nb, Ta, Ti, or Sn, the ruthenium oxide in which Mn, Nb, Ta, Ti, or Sn is dissolved and It becomes a melt composed of barium oxide and boron oxide. Even if the plate-like complex oxide is decomposed, the plate-like shape is maintained.

(3) Recovery of ruthenium oxide Lastly, from the obtained ruthenium oxide and glass composed of barium oxide and boron oxide, the glass components are dissolved with a solvent, and ruthenium oxide fine powder is recovered and washed as necessary. ·dry.
A method for dissolving boron oxide is not particularly limited, but a method using a mineral acid such as nitric acid, hydrochloric acid or sulfuric acid, or an organic acid aqueous solution such as formic acid or acetic acid as a solvent is simple. Among these, the use of mineral acids such as nitric acid, hydrochloric acid and sulfuric acid is preferred. The glass composed of ruthenium oxide and barium oxide and boron oxide is immersed in these acidic aqueous solutions, so that only the glass component is dissolved, and ruthenium oxide not dissolved in the acid can be recovered as a powder. The acid used for glass dissolution can be removed by washing with water.

2. Ruthenium oxide powder The plate-like ruthenium oxide powder obtained by the production method of the present invention is substantially composed of ruthenium oxide. When the ruthenium-barium composite oxide is mixed with boron oxide, Mn, Nb, Ta, When compounds containing at least one of Ti and Sn are mixed at the same time, a plate-like ruthenium oxide powder in which Mn, Nb, Ta, Ti, and Sn are dissolved can be obtained. The mixing amount of the compound is not particularly limited, but is preferably 5 to 30 wt%, more preferably 10 to 20 wt% with respect to the whole plate-like ruthenium oxide powder.

The plate-like ruthenium oxide powder has a shape as shown in FIGS. 1 and 2 when observed with a TEM (transmission electron microscope). The major axis is 1 × 10 ^{−6 to} 5 × 10 ⁻⁶ m and the thickness is 2 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. Further observation of the magnification shows that the plate-like powder is not a single crystal but a polycrystalline body in which fine primary particles are firmly bonded. When the substance is identified by X-ray diffraction, it is RuO ₂ (rutile), and the crystallite diameter is 1.0 × 10 ^{−8 to} 2.5 × 10 ⁻⁸ m.

3. Thick film resistor composition The present invention synthesizes a plate-like ruthenium oxide powder and uses it as a conductive component of the thick film resistor composition, thereby reducing the compounding of the glass binder and further between the conductive components. The specific resistance value of the thick film resistor is to be lowered by making the contact of the surface from point to surface.

So far, a method of obtaining a low resistance value with a thick film using a plate-like or flake-like Ag powder as a conductive component has been used for the production of a conductive resin paste made of a liquid thermosetting resin or thermoplastic resin. . The flaky Ag powder can be produced by adding a surfactant such as a fatty acid to the surface of the Ag powder obtained by a wet or dry process, and then crushing it with a ball mill or a stamp mill. This is a method that can be used because Ag has ductility unique to metals.
However, since ruthenium oxide has almost no ductility unlike Ag powder, it is not possible to obtain a plate-like or flake-like powder by crushing with a ball mill or a stamp mill. In addition, as described above, the ruthenium oxide powder can be synthesized by hydration oxidation in which an alkali oxide of Ru is hydrated by reduction with an organic reaction or an organic substance, or an aqueous chloride of Ru can be synthesized by a neutralization reaction. A method of baking an object in an oxidizing atmosphere is common (Patent Document 2). However, it is not possible to control the ruthenium oxide powder into a plate shape or flake shape by this general method.

  For this reason, in the present invention, as described above, a ruthenium compound and a barium compound are mixed and heat-treated in an oxidizing atmosphere to synthesize a plate-like ruthenium and barium composite oxide, which is again combined with boron oxide in an oxidizing atmosphere. Plate-like ruthenium oxide is synthesized by heat treatment. And glass powder is mix | blended with plate-like ruthenium oxide powder, or a thermosetting resin and / or a thermoplastic resin are mix | blended, and it is set as a thick film resistance composition.

(1) Glass powder When glass powder is blended with ruthenium oxide (RuO ₂ ) powder, the ratio of the two can be arbitrarily changed according to the intended sheet resistance value. That is, when the target resistance value is high, a small amount of ruthenium oxide (RuO ₂ ) powder is blended, and when the target resistance value is low, a large amount of ruthenium oxide (RuO ₂ ) powder is blended. A general weight ratio is ruthenium oxide (RuO ₂ ) powder: glass powder = 5: 95 to 50:50. If there is less ruthenium oxide (RuO ₂ ) powder than this, the resistance value becomes too high and becomes unstable. Further, if there is more ruthenium oxide (RuO ₂ ) powder than this, the formed resistor film becomes brittle. A preferred weight ratio is in the range of ruthenium oxide (RuO ₂ ) powder: glass powder = 5: 95 to 30:70.

The thick film resistor composition of the present invention may contain conductive particles other than ruthenium oxide (RuO ₂ ) powder, if necessary. These conductive particles include ruthenium oxides such as lead ruthenate having a pyrochlore crystal structure, bismuth ruthenate, calcium ruthenate having a perovskite crystal structure, strontium ruthenate, barium ruthenate, lanthanum ruthenate, and the like. , Ag, Pd and the like.
The thick film resistor composition of the present invention includes, in addition to ruthenium oxide (RuO ₂ ) powder and glass powder, adjustment of area resistance value and resistance temperature coefficient, adjustment of expansion coefficient, improvement of voltage resistance and other modifications. There may be any additives for quality purposes. The additives of the thick film resistor _{composition, MnO 2, CuO, TiO 2} , Nb 2 O 5, SiO 2, Al 2 O 3, ZrO 2, etc. ZrSiO ₄ are generally used. Moreover, the ratio of the additive is generally 0.05 to 20% with respect to the total weight of the ruthenium oxide (RuO ₂ ) powder and the glass powder.

(2) Resin Component The thick film resistor composition of the present invention is dispersed in a solvent in which a resin component called a vehicle is dissolved to form a thick film resistor paste. In the present invention, the present invention is not limited by the type and composition of the vehicle resin and solvent. As the resin component, ethyl cellulose, maleic resin, rosin and the like are generally used, and terpineol, butyl carbitol, butyl carbitol acetate and the like are generally used as the solvent. These blending ratios are adjusted according to the desired viscosity. Also, a solvent having a high boiling point can be added for the purpose of delaying the drying of the paste. The ratio of the vehicle to the resistor composition is not particularly limited, but is generally 30% to 100% by weight. A preferred vehicle amount is 30% to 80% by weight, and a more preferred vehicle amount is 30% to 50% by weight.

  In order to produce a thick film resistor paste by dispersing the composition for a thick film resistor of the present invention in a vehicle, a three-roll mill can be used, and in addition, a planetary mill, a bead mill, etc. can be used. The method for producing the paste is not limited. The thick film resistor composition of the present invention can be previously mixed with a ball mill or a rough machine and then dispersed in a vehicle.

In the thick film resistor paste, it is desirable to disaggregate the inorganic raw material powder and disperse it in a solvent in which the resin component is dissolved. In general, when the particle size of the powder becomes smaller, the aggregation becomes stronger and it becomes easier to form secondary particles. In particular, in the case of ruthenium oxide (RuO ₂ ) powder having a primary particle specific surface area of 3 × 10 ⁻⁹ m to 1.5 × 10 ⁻⁸ m, it is difficult to loosen the secondary particles and disperse them in the primary particles.
In order to produce such a thick film resistor paste by dispersing such ruthenium oxide (RuO ₂ ) powder and glass powder, it is effective to use a fatty acid as a dispersant. It is considered that the fatty acid has a function of adhering to the surface of ruthenium oxide (RuO ₂ ) powder and facilitating dispersion.
The fatty acid used in the present invention may be saturated or unsaturated, but higher fatty acids having 12 or more carbon atoms are more preferable from the viewpoint of dispersing ruthenium oxide (RuO ₂ ) powder and preventing aggregation again. The fatty acid may be added when the inorganic raw material powder is dispersed in the vehicle, or may be dispersed in the vehicle after preliminarily adhering to the ruthenium oxide (RuO ₂ ) powder.

Hereinafter, the method for producing a plate-like ruthenium oxide powder according to the present invention will be described with reference to examples, but the present invention is not limited to these examples.
In order to evaluate the shape and physical properties of the powder, the substance was identified by X-ray diffraction and the crystallite diameter was measured. The crystallite diameter can be calculated from the broadening of the peak of X-ray diffraction. Here, the peak of the rutile structure obtained by X-ray diffraction was waveform-separated into Kα1 and Kα2, and then the half width was measured as the spread of the peak of Kα1, and calculated from the Scherrer equation.

Example 1
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed in advance and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of Ru oxide hydrate thus obtained and 153 g of the barium oxide reagent were mixed with a raking machine and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>.
Moreover, when this composite oxide is observed by TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. It could be confirmed.
Next, the obtained composite oxide of ruthenium and barium was mixed with 60 g of boron oxide using a cracker and heat-treated at 800 ° C. for 1 hour in air.
Thereafter, the obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 130 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. Moreover, the crystallite diameter was 1.7 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate-like powder having a major axis of 2 × 10 ^{−6 to} 3 × 10 ⁻⁶ m and a thickness of 2 × 10 ^{−7 to} 3 × 10 ⁻⁷ m. Was confirmed.
Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.7 × 10 ⁻⁸ m.

(Example 2)
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. This Ru oxide hydrate was heat-treated at 600 ° C. for 1 hour to obtain a Ru oxide. 131 g of this Ru oxide and 195 g of the barium carbonate reagent were mixed with a cracker and baked in air at 800 ° C. for 1 hour to obtain 283 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 10 × 10 ⁻⁶ to 15 × 10 ⁻⁶ m and a thickness of 5 × 10 ^{−7 to} 7 × 10 ⁻⁷ m. Was confirmed.
The obtained composite oxide of ruthenium and barium was mixed with 283 g of boron oxide using a cracking machine, and heat-treated at 800 ° C. for 1 hour in air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 128 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. The crystallite diameter was 2.0 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate-like powder having a major axis of 3 × 10 ^{−6 to} 5 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm that there was.
Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 2.0 × 10 ⁻⁸ m.

(Example 3)
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of the hydrate of Ru oxide and 153 g of the barium oxide reagent were mixed with a cracker, and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm.
The obtained composite oxide of ruthenium and barium and 86 g of manganese dioxide powder were mixed with 150 g of boron oxide using a cracking machine and heat-treated at 800 ° C. for 1 hour in the air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 157 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. Further, the crystallite diameter was 1.5 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate-like powder having a major axis of 2 × 10 ^{−6 to} 3 × 10 ⁻⁶ m and a thickness of 2 × 10 ^{−7 to} 3 × 10 ⁻⁷ m. I was able to confirm that there was. Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.5 × 10 ⁻⁸ m.
Moreover, when the obtained ruthenium oxide fine powder was alkali-fused with sodium peroxide and sodium carbonate, the melt was made into a solution with hydrochloric acid and analyzed by IPC, the Mn content was 11 wt%.

Example 4
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of the hydrate of Ru oxide and 153 g of the barium oxide reagent were mixed with a cracker, and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm.
The obtained composite oxide of ruthenium and barium and 60 g of niobium pentoxide powder were mixed with 150 g of boron oxide using a cracking machine, and heat-treated at 800 ° C. for 1 hour in air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 150 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. The crystallite diameter was 1.2 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, a plate having a major axis of 1.5 × 10 ⁻⁶ to 2 × 10 ⁻⁶ m and a thickness of 1.5 × 10 ⁻⁷ to 2 × 10 ⁻⁷ m. It was confirmed that the powder was a powder. Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.2 × 10 ⁻⁸ m.
The obtained ruthenium oxide fine powder was alkali-melted with sodium peroxide and sodium carbonate, and the melt was made into a solution with hydrochloric acid and analyzed by IPC. As a result, the Nb content was 20 wt%.

(Example 5)
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of the hydrate of Ru oxide and 153 g of the barium oxide reagent were mixed with a cracker, and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm.
The obtained composite oxide of ruthenium and barium, and 50 g of tantalum pentoxide powder were mixed with 150 g of boron oxide using a cracker, and heat-treated at 800 ° C. for 1 hour in air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 172 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. Further, the crystallite diameter was 1.5 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate-like powder having a major axis of 2 × 10 ^{−6 to} 3 × 10 ⁻⁶ m and a thickness of 2 × 10 ^{−7 to} 3 × 10 ⁻⁷ m. I was able to confirm that there was. Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.5 × 10 ⁻⁸ m.
The obtained ruthenium oxide fine powder was alkali-fused with sodium peroxide and sodium carbonate, and the melt was made into a solution with hydrochloric acid and analyzed by IPC. The Ta content was 20 wt%.

(Example 6)
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of the hydrate of Ru oxide and 153 g of the barium oxide reagent were mixed with a cracker, and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm.
The obtained composite oxide of ruthenium and barium and 64 g of titanium dioxide powder were mixed with 150 g of boron oxide using a cracker and heat-treated at 800 ° C. for 1 hour in air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 193 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. The crystallite diameter was 1.2 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate having a major axis of 2 × 10 ^{−6 to} 2.5 × 10 ⁻⁶ m and a thickness of 2 × 10 ^{−7 to} 2.5 × 10 ⁻⁷ m. It was confirmed that the powder was a powder. Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.2 × 10 ⁻⁸ m. Moreover, when the obtained ruthenium oxide fine powder was alkali-fused with sodium peroxide and sodium carbonate, the melt was made into a solution with hydrochloric acid and analyzed by IPC, the Ti content was 21 wt%.

(Example 7)
Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The total amount of the hydrate of Ru oxide and 153 g of the barium oxide reagent were mixed with a cracker, and baked in air at 800 ° C. for 1 hour to obtain 285 g of a ruthenium-barium composite oxide powder. It was confirmed from the X-ray diffraction pattern that this ruthenium-barium composite oxide was a mixture of BaRuO ₃ <Hexagonal> and BaRuO ₃ <Cubic>. Further, when this composite oxide is observed with a TEM, it is a plate-like powder having a major axis of 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ m and a thickness of 3 × 10 ^{−7 to} 5 × 10 ⁻⁷ m. I was able to confirm.
The obtained composite oxide of ruthenium and barium and 50 g of tin dioxide powder were mixed with 150 g of boron oxide using a cracker and heat-treated at 800 ° C. for 1 hour in air.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 165 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. Moreover, the crystallite diameter was 1.7 × 10 ⁻⁸ m. When the obtained ruthenium oxide powder is observed with a TEM, it is a plate-like powder having a major axis of 2 × 10 ^{−6 to} 3 × 10 ⁻⁶ m and a thickness of 2 × 10 ^{−7 to} 3 × 10 ⁻⁷ m. I was able to confirm that there was. Further observation of a TEM image at a higher magnification confirmed that the plate-like powder was not a single crystal but a polycrystalline body in which fine primary particles were firmly bonded. This is supported by the fact that the crystallite diameter by X-ray diffraction is 1.7 × 10 ⁻⁸ m.
The obtained ruthenium oxide fine powder was alkali-melted with sodium peroxide and sodium carbonate, and the melt was made into a solution with hydrochloric acid and analyzed by IPC. As a result, the Sn content was 17 wt%.

(Comparative Example 1)
In the same manner as in Example 1, Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. Next, unlike Example 1, 60 g of boron oxide was added to the total amount of the Ru oxide hydrate obtained and 153 g of the barium oxide reagent, and the mixture was mixed with a separator and mixed in air at 800 ° C. for 1 hour. Heat treatment was performed.
The obtained melt was put into a solution of 4.5 L of pure water and 500 cm ³ of nitric acid, and 129 g of ruthenium oxide fine powder was recovered. When this ruthenium oxide fine powder was identified by X-ray diffraction, it was confirmed that it was a single phase of RuO ₂ <Rutile>. The crystallite diameter was 1.0 × 10 ⁻⁸ m. Even when the obtained ruthenium oxide powder was observed by TEM, it was not a plate-like powder. Further, when a TEM image with a higher magnification was observed, the powder was a fine powder almost identical to the crystallite diameter.

(Example 8)
36 parts by weight of the ruthenium oxide powder obtained in Example 1 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO: A resistance paste was made as a trial by kneading 24 parts by weight of glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three-roll mill.
Next, the resistor paste thus produced was printed on an alumina substrate on which electrodes were previously formed by Ag / Pd paste (Ag / Pd = 98.5 / 1.5), and the peak temperature was 850 ° C. and the peak time was 9 minutes. The resistor was formed by firing in a belt firing furnace. The resistor size was 0.3 mm width and 0.3 mm between the electrodes. The formed resistor was subjected to discharge of static electricity charged at 1 kV, 2 kV, and 3 kV to a 200 pF capacitor 10 times, and a change in resistance value was measured (this test is called an ESD test).
Film thickness of the formed resistor, resistance value before electrostatic discharge (initial resistance value), resistance temperature coefficient (TCR) between 25 ° C. and 125 ° C., and resistance value change rate (ESD change rate) after electrostatic discharge Are summarized in Table 1.

Example 9
36 parts by weight of the ruthenium oxide powder obtained in Example 3 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO A resistor paste was produced by kneading 24 parts by weight of glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three-roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Example 10)
36 parts by weight of the ruthenium oxide powder obtained in Example 4 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO A resistor paste was produced by kneading 24 parts by weight of glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three-roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Example 11)
36 parts by weight of the ruthenium oxide powder obtained in Example 5 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO A resistor paste was produced by kneading 24 parts by weight of glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three-roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Example 12)
36 parts by weight of the ruthenium oxide powder obtained in Example 6 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO A resistor paste was produced by kneading 24 parts by weight of glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three-roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Example 13)
36 parts by weight of the ruthenium oxide powder obtained in Example 7 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO A resistor paste was made by kneading 24 parts by weight of a glass frit of 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle by a three-roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Comparative Example 2)
According to a conventional method, Ru powder: 100 g, KOH: 800 g, KNO ₃ : 100 g were mixed and melted in a silver crucible at 700 ° C. for 3 hours to obtain potassium ruthenate (K ₂ RuO ₄ ). This potassium ruthenate was dissolved in pure water, 100 cm ³ of ethanol was added, washed with water and dried to obtain a Ru oxide hydrate. The ruthenium oxide hydrate was heat-treated at 600 ° C. for 1 hour to obtain ruthenium oxide. The shape of the ruthenium oxide was granular.
36 parts by weight of the obtained ruthenium oxide powder, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: 20 wt%, ZnO: 15 wt%. 24 parts by weight of glass frit and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle were kneaded by a three-roll mill to produce a resistor paste.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Comparative Example 3)
36 parts by weight of the non-plate-like ruthenium oxide powder obtained in Comparative Example 1 above, SiO ₂ : 35 wt%, B ₂ O ₃ : 20 wt%, Al ₂ O ₃ : 5 wt%, CaO: 5 wt%, BaO: A resistor paste was prototyped by kneading 24 parts by weight of glass frit of 20 wt% and ZnO: 15 wt% and 40 parts by weight of organic cellulose dissolved in terpineol as an organic vehicle using a three roll mill.
Next, in the same manner as in Example 8, a resistor was formed from the prototype resistor paste, an ESD test was performed, and the results are summarized in Table 1.

(Example 14)
70 parts by weight of the ruthenium oxide powder obtained in Example 1, 10 parts by weight of a resol type phenol resin, and 20 parts by weight of butyl cellosolve were kneaded by a three-roll mill to produce a resistor paste.
Next, the prototype resistor paste was printed on an alumina substrate on which an electrode was previously formed with an Ag / Pd paste (Ag / Pd = 98.5 / 1.5) and placed in an oven maintained at a temperature of 200 ° C. for 30 minutes. The phenol resin was cured to form a resistor. The resistor size was 0.3 mm width and 0.3 mm between the electrodes.
Table 2 shows the film thickness, resistance value, and resistance temperature coefficient (TCR) between 25 ° C. and 125 ° C. of the formed resistor.

(Comparative Example 4)
70 parts by weight of the ruthenium oxide powder obtained in Comparative Example 1, 10 parts by weight of a resol type phenol resin, and 20 parts by weight of butyl cellosolve were kneaded by a three-roll mill to produce a resistor paste.
Next, in the same manner as in Example 14, a resistor was formed from the prototype resistor paste, and the film thickness, resistance value, and resistance temperature coefficient (TCR) between 25 ° C. and 125 ° C. were formed. The results are summarized in Table 2.

"Evaluation"
As is apparent from the results in Table 1, the thick film resistors (Examples 8 to 13) using the ruthenium oxide (Examples 1 to 7) produced according to the present invention as conductive materials have a ruthenium oxide plate shape. Therefore, there was little change in the resistance value due to electrostatic discharge, and no crack was observed in the fired film of the resistor even when the resistor film was discharged with 3 kV static electricity. On the other hand, in the resistors of Comparative Examples 2 and 3 in which the ruthenium oxide manufactured by the conventional method is a conductive material, the ruthenium oxide is granular or non-plate-like, so that fine cracks are generated in the fired film. However, when static electricity is discharged, this fine crack spreads and the resistance value changes to positive, and when the discharge voltage is further increased, the crack further spreads and the resistor film is destroyed, resulting in a large positive resistance value change. Indicated.
Further, it can be seen from Table 2 that the resin-cured thick film resistor using the ruthenium oxide of the present invention produced in Example 14 as a conductive material has a low resistance value and a resistance temperature coefficient close to 0. On the other hand, the resin-cured thick film resistor using the ruthenium oxide manufactured in Comparative Example 4 as a conductive material has an extremely high resistance value and a large negative temperature coefficient of resistance. In Example 14, the conductive particles are in contact with each other because the plate-like conductive powder is used, whereas in Comparative Example 4, the conductive particles are in contact with each other at points. It is thought that it became unstable.

  The thick film resistor composition using the plate-like ruthenium oxide powder of the present invention has a strong structure of the fired film even when the compounding ratio of the plate-like ruthenium oxide powder, which is a conductive component, to the glass binder is increased. Since the change in resistance value is small even when a current is applied, it can be widely used in the manufacture of thick film resistors such as chip resistors, thick film hybrid ICs, and resistor networks. As a result, the thick film resistor composition is useful for the manufacture of electronic components such as chip resistors whose size has been miniaturized in recent years.

Claims (12)

A step of synthesizing a plate-shaped composite oxide of ruthenium and barium by heat-treating a mixture of a ruthenium compound and a barium compound at an oxidizing atmosphere and at a temperature of 400 ° C. or higher. After mixing boric acid, a heat treatment is performed at a temperature of 500 ° C. or higher to form a plate-like composite oxide in the plate-like ruthenium oxide powder, boron oxide and barium oxide melt, and the resulting melt A method for producing a plate-like ruthenium oxide powder comprising a step of adding a solvent, dissolving boron oxide and barium oxide, and collecting the plate-like ruthenium oxide powder. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein the ruthenium compound is a Ru oxide wet-synthesized from a solution containing Ru. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein the barium compound is at least one selected from barium oxide, barium carbonate, barium nitrate, barium chloride, or barium sulfate. 2. The plate-like ruthenium oxide powder according to claim 1, wherein a mixing ratio of the ruthenium compound and the barium compound is 0.8: 1.2 to 1.2: 0.8 in a molar ratio of ruthenium: barium. Manufacturing method. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein, in the step of synthesizing the plate-like composite oxide, the heat treatment temperature of the mixture is 400 to 1000 ° C. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein the boron oxide or boric acid is 20 parts by weight or more based on 100 parts by weight of the plate-like composite oxide in terms of boron oxide. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein the heat treatment temperature is 500 to 1000 ° C in the step of melting the plate-like composite oxide. By mixing the boron oxide or boric acid with a compound further containing at least one selected from Mn, Nb, Ta, Ti, or Sn and performing a heat treatment, the Mn, Nb, Ta, Ti, or Sn element is changed. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein a solid-form plate-like ruthenium oxide powder is obtained. The method for producing a plate-like ruthenium oxide powder according to claim 1, wherein in the step of collecting the plate-like ruthenium oxide powder, the solvent added is an aqueous solution of a mineral acid or an organic acid. The major axis obtained by the production method according to claim 1 is 1 × 10 ^{−6 to} 5 × 10 ⁻⁶ m, and the thickness is 1.5 × 10 ^{−7 to} 5 × 10 ^−7. A plate-like ruthenium oxide powder which is m. A thick film resistance composition obtained by blending glass powder with the plate-like ruthenium oxide powder according to claim 10. A thick film resistor composition obtained by blending the plate-like ruthenium oxide powder of claim 10 with a thermosetting resin and / or a thermoplastic resin.

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