KR20140025338A - Ruthenium oxide powder, composition for thick film resistor elements using same, and thick film resistor element - Google Patents

Abstract

Provides ruthenium oxide powder which can be manufactured at low cost as an electronic component material such as a tip resistor, a hybrid IC, or a resistance network having a sufficient performance even with a low ruthenium content, a composition for thick film resistors using the same, and a thick film resistor do.
Ruthenium oxide (RuO ₂ ) powder having a rutile crystal structure, characterized in that the crystallite diameter measured by its X-ray diffraction method (110) is 3 to 10 nm, and the Ru content is not less than 73 mass%. Ruthenium powder; A composition for thick film resistors comprising a conductive powder composed of ruthenium oxide powder and a glass powder as main components; The thick film resistor composition is a thick film resistor paste dispersed in an organic vehicle containing a fatty acid, and the content of the fatty acid is provided by a thick film resistor paste or the like, which is 0.1 to 10 parts by weight based on 100 parts by weight of ruthenium oxide.

Description

Ruthenium oxide powder, composition for thick film resistor elements using same, and thick film resistor element}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ruthenium oxide powders, compositions for thick film resistors and thick film resistors using the same, and are inexpensive as electronic component materials such as tip resistors, hybrid ICs, or resistance networks that have sufficient performance even if the ruthenium content is low. A ruthenium oxide powder that can be produced, a composition for thick film resistors and a thick film resistor using the same.

Generally, thick film resistors, such as a tip resistor, a hybrid IC, or a resistance network, are formed by printing and baking a thick film resistor paste on a ceramic substrate. As the composition for thick film resistors, those having main components as ruthenium oxide powder and glass powder represented by ruthenium oxide as the conductive particles are widely used.

The reason that ruthenium oxide and glass powder are used for the thick film resistor is that the firing in the air can be performed, and the resistance temperature coefficient (TCR) can be brought close to zero. Etc. can be mentioned.

In the composition for thick film resistances which consist of ruthenium oxide and glass powder, resistance value changes with the compounding ratio. If the compounding ratio of the ruthenium oxide which is a conductive particle is large, a resistance value will fall, and reducing a compounding ratio of a conductive material will raise a resistance value. By using this, a thick film resistor adjusts the compounding ratio of ruthenium oxide and glass powder, and expresses a desired resistance value.

The most common ruthenium oxide is ruthenium oxide (RuO ₂ ) having a rutile crystal structure, and has the lowest resistivity among the types of ruthenium oxide described below. In the combination of ruthenium oxide (RuO ₂ ) powder and glass powder, generally, a resistor in a region of 10 ⁻² Ω · cm to 10 ⁴ Ω · cm (10 ^-4 Ω · m to 10 ² Ω · m) is formed. can do.

Ruthenium oxides include ruthenium oxide (RuO ₂ ) having a rutile crystal structure, lead ruthenium oxide having a crystal structure of pyrochlore-type, ruthenium acid bismuth, and perovskite crystal structures. Calcium ruthenate, strontium ruthenate, barium ruthenate, and lanterns of ruthenate are all oxides exhibiting metallic conductivity.

Ruthenium oxide (RuO ₂ ) having a rutile type crystal structure is coated with at least one of, for example, KOH and NaOH, and roasted again, for example, to RuO ₂ particles obtained by roasting an amorphous ruthenium oxide hydrate. It is manufactured by the method of washing, washing | cleaning, drying, etc. (refer patent document 4).

Thick film resistance compositions composed of ruthenium oxide and glass powder are widely used because of excellent resistance characteristics, but ruthenium is an expensive precious metal, and thick film resistors using the same have a high price.

For this reason, about the composition for thick film resistance of the low resistance value area | region which is hard to reach | attach with the combination of ruthenium oxide and glass powder, the desired resistance value is expressed by adding palladium and silver as a electrically conductive material. However, palladium is a precious metal that is more expensive than ruthenium, and the thick film resistor in the region having low resistance has a disadvantage in that the price is high. In addition, since ruthenium and palladium have low outputs, price fluctuations are severe and raw material prices for the manufacture of thick film resistors are not stable. In particular, even in a thick film resistor having a low resistance value, since the content of ruthenium or palladium is high, the price is high and the product price becomes unstable. Therefore, a low priced thick film resistor composition which greatly reduces the amount of ruthenium and palladium in a ruthenium and a low resistance region is preferable.

Until now, an example of using ruthenium oxide (RuO ₂ ) having a small particle diameter in a thick film resistor has been disclosed in Japanese Patent Application Laid-Open No. 7-22202 (Patent Document 1). This patent document 1 describes that the durability against electrostatic discharge (ESD) is improved by using ruthenium oxide having a large specific surface area, and the oxidation has a specific surface area of 50 m ² / g or more and a crystallite size of 25 nm or less. Examples of thick film resistor compositions using solids of ruthenium are given. However, in the examples described herein, the largest specific surface area is 51.9 m ² / g, and the smallest crystallite size is 13.3 nm. At such a specific surface area and crystallite size, ruthenium cannot be reduced as long as a sufficient economic effect can be obtained as a composition for thick film resistors.

In addition, Japanese Patent Application Laid-open No. Hei 8-217459 (Patent Document 2) describes an example in which ruthenium oxide powder having a specific surface area of 70 m ² / g or more is produced (Example). However, there is no description of the determinant. In addition, ruthenium oxide having low completeness of crystallized crystals having a maximum ruthenium content of ruthenium oxide of 73.9%, and a thick film resistor using such ruthenium oxide powder has a high resistance value and can reduce ruthenium as a composition for thick film resistors. none.

In addition, Japanese Patent Laid-Open No. 4-290401 (Patent Document 3) also describes a resistor paste containing ruthenium oxide having a specific surface area of 200 m ² / g as conductive particles (Example). However, this also has no description of crystallites, and since it is described as ruthenium oxide to which 20% of H ₂ O is added, the completeness of the hydrated crystal is low.

Prior art literature

<Patent Documents>

-Patent Document 1: Japanese Patent Laid-Open No. 7-22202

-Patent Document 2: Japanese Patent Application Laid-open No. Hei 8-217459

-Patent Document 3: Japanese Patent Application Laid-Open No. 4-290401

-Patent Document 4: Japanese Patent Application Laid-open No. Hei 8-268722

An object of the present invention is a ruthenium oxide powder which can be manufactured at low cost from electronic component materials such as a tip resistor, a hybrid IC, or a resistance network having sufficient performance even with a low ruthenium content, a composition for a thick film resistor using the same, and It is to provide a thick film resistor.

MEANS TO SOLVE THE PROBLEM The present inventors conducted extensive research in order to solve the above-mentioned conventional subject, and, as a result, using ruthenium oxide with high crystallinity in the composition for thick film resistors whose electroconductive particle and glass powder are a main component, It is found that even when the crystallite diameter is minute, grain growth is suppressed during firing of the resist paste, and by using such ruthenium oxide (RuO ₂ ) as a raw material, a low-resistance thick film resistor composition having a low resistance value and a reduced ruthenium content rate It confirmed that it can provide, and came to complete this invention.

That is, according to the first invention of the present invention, it is a ruthenium oxide (RuO ₂ ) powder having a rutile crystal structure, the crystallite diameter measured by the (110) plane by X-ray diffraction method is 3 to 10 nm, Ruthenium oxide powder is provided in which Ru content is 73 mass% or more.

According to the second invention of the present invention, in the first invention, the ruthenium oxide powder is characterized in that the specific surface area of the ruthenium oxide (RuO ₂ ) powder is 70 m ² / g or more and 200 m ² / g or less.

According to the third invention of the present invention, in the first or second invention, the ruthenium oxide (RuO ₂ ) powder has a ratio of the crystallite diameter D1 and the specific surface area diameter D2 satisfying the following formula (1). Is provided.

D1 / D2? (One)

(However, the crystallite diameter D1 is the measured value (nm) in the (110) plane of the rutile crystal structure according to the X-ray diffraction method, and the specific surface area diameter D2 is the specific surface area of the powder S (m ² / g), specific gravity Is a calculated value (nm) of 6 × 10 ⁻⁶ / (ρ · S) when expressed as ρ (g / cm ³ ).

According to the 4th invention of this invention, the composition for thick film resistors which mix | blends electroconductive particle which consists of ruthenium oxide powder and glass powder with any one of 1st-3rd invention as a main component is provided.

According to the fifth invention of the present invention, in the fourth invention, at least one of silver (Ag) powder, palladium (Pd) powder, or oxide powder of silver powder coated with palladium and precious metal powder is further blended as conductive particles. A composition for thick film resistors is provided.

According to the 6th invention of this invention, in 4th or 5th invention, electroconductive particle and glass powder are mix | blended in the range of 5: 95-70: 30 by mass ratio, The composition for thick film resistors is provided.

According to the 7th invention of this invention, the composition for thick film resistors in any one of 4th-6th invention whose glass powder has a 50% cumulative particle size of 5 micrometers or less is provided.

According to the eighth invention of the present invention, the thick film resistor composition according to any one of the fourth to seventh inventions is a thick film resistor paste dispersed in an organic vehicle containing a fatty acid, and the fatty acid content is 100 parts by weight of ruthenium oxide. It is provided with a thick film resistor paste, characterized in that 0.1 to 10 parts by weight relative to.

According to the ninth invention of the present invention, in the eighth invention, a thick film resistor paste is provided wherein the fatty acid is a higher fatty acid having 12 or more carbon atoms.

According to the 10th invention of this invention, in 8th invention, electroconductive particle and glass powder are mix | blended in the range of 5: 95-70: 30 by mass ratio, The thick film resistor paste is provided.

According to the eleventh invention of the present invention, there is provided a thick film resistor formed by baking the composition for a thick film resistor according to any one of the fourth to seventh inventions on a ceramic substrate.

According to the twelfth invention of the present invention, there is provided a thick film resistor formed by applying the thick film resistor paste according to any one of the eighth to tenth inventions to a ceramic substrate and then baking.

According to the method of the present invention, ruthenium oxide (RuO ₂ ) powder having a rutile crystal structure has a crystallite diameter of 3 to 10 nm and its Ru content is measured by measuring its (110) plane by X-ray diffraction. Since it is 73 mass% or more and high crystallinity, grain growth is suppressed at the time of baking the resist paste while being fine. The effect of this is that the specific surface area of ruthenium oxide (RuO ₂ ) is larger than a specific range, and the specific surface area diameter calculated from the specific surface area and specific gravity is determined in the crystallite diameter in which the (110) plane is measured by the X-ray diffraction method. If it exists in a specific range, a larger effect will be acquired.

Therefore, by using the ruthenium oxide (RuO ₂ ) powder of this invention as a raw material, the composition for thick film resistors and thick film resistor paste which are excellent in cost efficiency at low cost can be provided.

Moreover, according to the present invention, by using such a ruthenium oxide powder as a composition for thick film resistors and baking on a ceramic substrate, a high performance thick film resistor can be formed.

Hereinafter, the ruthenium oxide powder of this invention, the composition for thick film resistors, and thick film resistor using the same are demonstrated in detail.

1. Ruthenium Oxide Powder

The ruthenium oxide powder of the present invention is a ruthenium oxide (RuO ₂ ) powder having a rutile crystal structure, having a crystallite diameter of 3 to 10 nm and its Ru content of 73 measured by its X-ray diffraction method. It is characterized by the above-mentioned mass%.

Ruthenium oxide (RuO ₂ ) powder for thick film resistors is generally produced by heat treating a hydrated ruthenium oxide powder synthesized by wet, and the particle size and crystallinity are different depending on the synthesis method and heat treatment conditions. In addition, the characteristics also vary depending on the particle size and crystallinity. An object of the present invention is to provide a thick film resistor having a desired resistance value at low cost by satisfying the following condition (a) in the particle size and crystallinity of ruthenium oxide (RuO ₂ ) powder.

(a) Ruthenium oxide (RuO ₂ ) powder whose crystallite diameter is 3-10 nm and Ru content is 73 mass% or more, measured by the (110) plane of a rutile crystal structure by X-ray diffraction method.

Ruthenium oxide (RuO ₂ ) powder, which is a raw material for a thick film resistor, has a small particle size of the primary particles, and when the primary particles can be regarded as almost single crystals, the particle diameter can be substituted by the crystallite diameter measured by the X-ray diffraction method. In ruthenium oxide (RuO ₂ ) having a rutile crystal structure, although the diffraction peaks of the (110), (101), (211), (301) and (321) planes of the crystal structure are relatively large among the diffraction peaks, In the present invention, the crystallite diameter measured in the (110) plane must be 3 to 10 nm.

The resistance value of the thick film resistor is evaluated as an area resistance value in which the ratio of the resistor width and the resistor length is 1: 1. In the composition for thick film resistors whose ruthenium oxide (RuO ₂ ) powder and the glass powder are the main constituents, even if these compounding ratios are the same, the area resistance values represented by the particle size of the raw material powder are different. As described above, ruthenium oxide powder having a particle size of 15 nm to 500 nm and glass powder having a particle size of 500 nm to 10 μm are generally used in the thick film resistor.

When ruthenium oxide (RuO ₂ ) powder having a particle size of 15 nm or more is used, the smaller the particle size, the lower the resistance value is. Although this may not be the case, examples of thick film resistors made from ruthenium oxide (RuO ₂ ) powder having a particle diameter of 3 nm to 15 nm are hardly noticeable.

In ruthenium oxide (RuO ₂ ) powder having a small particle diameter, it is considered that the distance between the ruthenium oxide (RuO ₂ ) particles in the thick film resistive film formed by firing the resistance paste becomes small, and the area resistance value is lowered. However, if the particle size of the ruthenium oxide (RuO ₂ ) powder is made too small, the growth of ruthenium oxide (RuO ₂ ) particles occurs during the firing of the resist paste, and the distance between the ruthenium oxide (RuO ₂ ) increases, resulting in a high area resistance value. I think.

Because of this, in the present invention, particle size is small and the resistance paste firing the ruthenium oxide grain growth is inhibited in (RuO ₂₎ low-thick film resistor composition of the powder by using as a raw material, a low resistance value reducing the ruthenium content To get. If the crystallite diameter of the ruthenium oxide (RuO ₂ ) powder is less than 3 nm, the growth of particles occurs during firing as described above, resulting in a problem that the area resistance value becomes high. On the contrary, when the crystallite diameter exceeds 10 nm, the area resistance value becomes high. there is a problem. Ruthenium oxide (RuO ₂₎ crystallite diameter of the powder is more preferably 3.2 ~ 9.8 nm.

In the present invention, and should the Ru content of ruthenium oxide (RuO ₂₎ be at least 73% by weight. If the Ru content is less than 73% by mass, the crystallinity is low, so that there is a problem that growth of ruthenium oxide particles occurs during firing of the resistance paste, resulting in an increase in the area resistance value. It is preferable that Ru content is 74 mass% or more.

In the present invention, the ruthenium oxide (RuO ₂ ) powder for a thick film resistor needs to satisfy the above conditions, but more preferably satisfies the following condition (b), and more preferably satisfies the condition (c). Do. Thereby, the area resistance value of a thick film resistor does not become high and a lower cost thick film resistor can be provided.

(b) Ruthenium oxide (RuO ₂ ) powder having a specific surface area of at least 70 m ² / g and at most 200 m ² / g.

(c) The crystallite diameter measured on the (110) plane of the rutile crystal structure according to the X-ray diffraction method, D1 (nm), the specific surface area of the conductive particles S (m ² / g), specific gravity ρ (g / cm ³⁾ nd represented ^{by, 6 × 10 -6 / (ρ} · S) to calculate a specific surface area diameter D2 (nm) D1 / D2≥0.70 a ruthenium oxide (RuO ₂₎ as a powder that is.

Ruthenium oxide (RuO _2), if the specific surface area of the powder was 70 m ² / g less than the higher the resistance value when a thick film resistor can not be obtained the effect of reducing the ruthenium content. Moreover, when it exceeds 200 m <^2> / g, since dispersion in a thick film resistor paste will fall and the ruthenium oxide powder will aggregate, the resistance value of a thick film resistor will become high and a reduction effect of a ruthenium content rate cannot be acquired. Preferred specific surface areas are 75 to 190 m ² / g.

Since the particle size of the primary particles of ruthenium oxide (RuO ₂ ) powder used for the thick film resistor is small, it can be represented by the crystallite diameter or the specific surface diameter. And when a primary particle can be seen as a nearly single crystal, a particle diameter can be substituted by the crystallite diameter measured by the X-ray-diffraction method. As the crystallite becomes smaller, the crystal lattice that completely satisfies the Bragg condition is reduced, and the diffraction line profile when the X-ray is irradiated is spread. If there is no lattice distortion, the crystallite diameter is measured from the Scherrer equation below with a crystallite diameter of D1 (nm), an X-ray wavelength of λ (nm), an extension of the diffraction line profile to β, and a diffraction angle of θ. .

D 1 (nm) = (K · λ) / (β · cosθ)... (2)

(Where K is a Scherrer integer, using 0.9)

As described above, in ruthenium oxide (RuO ₂ ) having a rutile crystal structure, the diffraction peaks of the (110), (101), (211), (301) and (321) planes of the crystal structure are among the diffraction peaks. Is relatively large, and it is possible to calculate the crystallite diameter from the enlargement of this diffraction line profile.

On the other hand, the specific surface diameter becomes larger when the particle diameter of the powder becomes finer. Thus, if the particle size of the powder is D2 (nm), the density is ρ (g / cm ³ ), and the specific surface area is S (m ² / g), the following relation holds when the powder is in the shape of a sphere or a cube. do. The particle diameter calculated by this D2 is called a specific surface area diameter.

D ² (nm) = 6 × 10 ³ / (ρ · S). (3)

When the powder of ruthenium oxide (RuO ₂ ) is polycrystalline, or when crystal integrity is insufficient due to hydration or the like, the specific surface area diameter D2 becomes larger than the crystallite diameter D1, and the ratio of D1 to D2, that is, D1 / D2 Is less than 1. Therefore, the value of D1 / D2 serves as a criterion of crystal integrity of the particles, and it can be judged that the integrity of the crystals forming particles as low as D1 / D2 is low, and the integrity of crystals as high as D1 / D2 is high. In general, as the powder becomes finer, the integrity of the crystals forming the particles decreases, and the value of D1 / D2 tends to decrease. In the present invention, since the crystallinity is high and close to the single crystal, it is preferable that D1 / D2? 0.70. More preferably, D1 / D2 ≧ 0.73.

2. Manufacturing Method of Ruthenium Oxide Powder

The ruthenium oxide (RuO ₂ ) powder for the thick film resistor is not limited by its production method, but is preferably produced by heat-treating the hydrated ruthenium oxide powder synthesized in a wet manner. In such a manufacturing method, particle size and crystallinity differ depending on the synthesis method and heat treatment conditions.

Examples of the Ru solution and synthesis method for synthesizing the Ru oxide hydrate include a method of adding ethanol to a K ₂ Ru ₂ O ₄ aqueous solution, or a method of neutralizing the RuCl ₃ aqueous solution with KOH or the like.

The hydrated ruthenium oxide powder is subjected to heat treatment at a temperature exceeding 400 ° C. in an oxidizing atmosphere, whereby crystallized water can be taken up, thereby increasing the crystallinity of the powder. Here, an oxidizing atmosphere is gas containing 10 volume% or more of oxygen, For example, air can be used.

If the temperature of the heat treatment is lower than 400 ° C, ruthenium oxide is not completely produced, and if it exceeds 800 ° C, the ruthenium oxide becomes too large or the ruthenium becomes hexavalent or octavalent oxide (RuO ₃ or RuO ₄ ) and volatilizes. The ratio is high, which is undesirable. Therefore, the heat treatment temperature is generally set to 500 to 800 ° C. In addition, the time of appropriate heat processing is appropriately set by heat processing temperature, the atmosphere of heat processing, a heat processing method, etc. If the heat treatment time is 1 hour or more, the particle size of the ruthenium oxide becomes large, especially at high temperatures, and ruthenium tends to volatilize into a hexavalent or octavalent oxide (RuO ₃ or RuO ₄ ). 40 minutes or less are preferable and 30 minutes or less are more preferable.

3. Thick Film Resistor Composition

The present invention synthesizes a ruthenium oxide powder having a specific crystallite diameter and has a specific ruthenium content, and uses it as a conductive component of a composition for thick film resistors, thereby reducing the compounding amount of ruthenium oxide and obtaining an inexpensive thick film resistor. will be.

That is, this invention provides the composition for thick film resistors which mix | blends electroconductive particle which consists of ruthenium oxide powder, and glass powder as a main structural component.

(1) conductive particles

The present invention, use of the ruthenium oxide as the conductive powder in front of the particle, but is for a thick film resistor composition of the present invention, it may include conductive particles, other than ruthenium (RuO ₂₎ oxide powder, if necessary. As such electroconductive particle, the silver powder (Ag) powder, the palladium (Pd) powder, or the oxide powder of silver powder coated with palladium, and a noble metal powder are mentioned. The shape is not particularly limited in terms of spherical shape, flake shape and the like, and the average particle diameter is preferably 0.1 to 10 µm.

In addition, ruthenium oxides such as lead ruthenate, bismuth ruthenic acid, calcium ruthenate, strontium ruthenate, barium ruthenate, and ruthenate lantern having a pyrochroma type crystal structure can be used. Can be mentioned.

(2) glass powder

Glass powder is not limited by the composition and the manufacturing method. Lead aluminoborosilicates containing lead are generally used for thick film resistors, and lead-free compositions such as zinc borosilicate, calcium borosilicate, and barium borosilicate are used. Glass powder is also used. Generally, glass is manufactured by mixing a predetermined component or such a precursor in the same compound | mixing which can obtain a desired resistance value, melt | dissolving these, and quenching them. The melting temperature is about 1400 degreeC, and quenching is often performed by pouring a melt into cold water and flowing it on the belt. The grinding of the glass is carried out to a desired particle size with a ball mill, a vibration mill, a planetary mill, a bead mill, or the like.

The particle diameter of the glass powder is not limited, but the 50% cumulative particle size of the particle size distribution system using laser diffraction is preferably 5 µm or less, more preferably 3 µm or less. If the particle size of the glass powder is too large, the area resistance value of the fired thick film resistor is lowered, but the imbalance of the area resistance value is increased, so that inconveniences such as a decrease in product yield and a load characteristic are increased.

Of the conductive particles and the glass powder such as ruthenium oxide (RuO ₂₎ powder may optionally be replaced by an area resistance value of interest. That is, electroconductive particle is mix | blended little when the target resistance value is high, and electroconductive particle is mix | blended many when the target resistance value is low. Preferable weight ratio is the range of electroconductive particle: glass powder = 5: 95-70: 30. If there is less electroconductive particle than this, resistance value becomes high too much and becomes unstable. On the contrary, when there are more electroconductive particles than this, the resistive film formed will fall.

In addition to ruthenium oxide (RuO ₂ ) powder and glass powder, the composition for thick film resistors of the present invention may contain additives for the purpose of adjusting the area resistance value, the resistance temperature coefficient, the adjustment of the expansion coefficient, the improvement of the voltage resistance and other modifications. There is no obstacle. As an additive of the composition for thick film resistors, MnO ₂ , CuO, TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrSiO _4, and the like are generally used. In addition, the proportion of the additive is generally 0.05 to 20% based on the total weight of the ruthenium oxide (RuO ₂ ) powder and the glass powder.

(3) resin components

When the composition for thick film resistors of this invention is disperse | distributed in the solvent which melt | dissolved the resin component called a vehicle, it becomes a thick film resistor paste. In this invention, it is not limited by the kind or compounding of resin of a vehicle, and a solvent. As the resin component, ethyl cellulose, maleic acid resin, rosin, and the like are generally used. As a solvent, terpineol, butyl carbitol, butyl carbitol acetate and the like are generally used. This blending ratio is adjusted by the desired viscosity. Moreover, a solvent with high boiling point can also be added for the purpose of slowing drying of a paste. The ratio of the vehicle to the composition for the resistor is not particularly limited, but is 30% to 100% by weight.

In order to manufacture the thick film resistor paste by dispersing the composition for thick film resistors of the present invention in a vehicle, an oil mill, a bead mill, or the like can be used in addition to the three-roll mill, but is not limited to the method for producing the paste. The composition for thick film resistors of the present invention may be previously mixed with a ball mill or brain trachea, and then dispersed in a vehicle.

In the thick-film resistor paste, it is preferable to loosen the inorganic raw material powder and disperse in the solvent in which the resin component is dissolved. In general, the smaller the particle size of the powder, the stronger the aggregation and the easier it is to form secondary particles. In the ruthenium oxide (RuO ₂ ) powder of the present invention, it is effective to use a fatty acid as a dispersant in order to facilitate dissociation of secondary particles into primary particles. Fatty acid is believed to have a function of adhering to the surface of ruthenium oxide (RuO ₂ ) powder to facilitate dispersion.

Fatty acid used in the present invention include, but are not ask whether saturated, unsaturated, in terms dispersing ruthenium (RuO ₂₎ oxide powder that prevents re-agglomeration, it is the number of carbon atoms is more preferred more than 12 higher fatty acid. The fatty acid may be added when the inorganic raw material powder is dispersed in the vehicle, or may be previously attached to the ruthenium oxide (RuO ₂ ) powder and then dispersed in the vehicle.

4. Thick Film Resistor

The thick film resistor of the present invention is a thick film resistor obtained by baking the composition for thick film resistors on a ceramic substrate, and is a thick film resistor formed by applying the thick film resistor paste to a ceramic substrate and then baking.

Ru content in the inorganic component in a thick film resistor is adjusted with the magnitude | size of a desired resistance value. For example, in order to obtain a thick film resistor having a resistance value of around 1 KΩ, it is economical to have a Ru content of 18% or less, particularly 15% or less. It is necessary to make content rate high. In the present invention, the Ru content in the inorganic component of the thick film resistor is set to 23% by mass or less, so that a wide range of resistance values can be met.

Hereinafter, the preparation of the ruthenium oxide powder according to the present invention, a composition for thick film resistors and a thick film resistor using the same will be described based on Examples, but the present invention is not limited to these Examples.

In order to evaluate the shape and physical properties of the ruthenium oxide powder, the material classification and crystallite diameter were measured by X-ray diffraction. The crystallite diameter can be calculated from the peak of X-ray diffraction. Here, the peaks of the rutile structure obtained by X-ray diffraction are separated into waveforms of Kα1 and Kα2, and then the half-value width is measured by the magnification of the peak of Kα1 which is corrected by the optical system of the measuring instrument. Calculated.

The formed thick film resistors discharged film thickness, resistance value, resistance temperature coefficient (COLD-TCR) from 25 ° C to 55 ° C, resistance temperature coefficient (HOT-TCR) from 25 ° C to 125 ° C, current noise, and static electricity. The resistance change rate (ESD characteristic) at the time of evaluation was evaluated.

The film thickness averaged the value which measured the film thickness of five thick film resistors with the thickness roughness meter of a stylus.

In addition, the resistance value averaged the value which measured the resistance values of 25 thick film resistors with the digital multimeter.

The resistance temperature coefficient was maintained at -55 ° C, 25 ° C, and 125 ° C for 15 minutes in each of the thick film resistors, and then measured the respective resistance values (R _-55 , R ₂₅ , R ₁₂₅ ), and the following equation (4) And (5), the average of five thick film resistors was taken.

COLD-TCR (ppm / ° C) = (R _-55 -R ₂₅ ) / R ₂₅ / (-80) x 10 ⁶ . (4)

HOT-TCR (ppm / ° C.) = (R ₁₂₅ -R ₂₅ ) / R ₂₅ / (100) x 10 ⁶ . (5)

The current noise was measured by applying a voltage of 1/10 W in a Quan-Tech company MODEL315C, represented by a noise index, and averaged at five thick film resistors.

The ESD characteristics are charged to a 200 pF-0Ω unit at a voltage of 1 KV, and then discharged to a thick film resistor, whereby the resistance value before discharge is R ₀ and the resistance value after discharge is R ₁ . It calculated by following formula (6). The change rate was measured and averaged with five thick film resistors.

ESD characteristic (%) = (R ₁ -R ₀ ) / R ₀ × 100... (6)

(Examples 1 to 12)

In Example 1, ruthenium oxide was synthesize | combined in aqueous solution using the aqueous solution which melt | dissolved potassium ruthenate as a raw material, this was solid-liquid separated, and it washed and dried at 80 degreeC, and obtained the ruthenium oxide powder. Ruthenium oxide after drying had a ruthenium content rate of 61.5 mass%, and was an oxidized hydrate. Heat treatment for 10 min this ruthenium oxide powder after drying to 650 ℃ to, Ru content of the ruthenium oxide to give a 73.8 mass% (RuO ₂₎ powder. On the other hand, in Examples 2-12, unlike Example 1, the ruthenium oxide powder after drying changed the heat processing conditions in the range of 680-800 degreeC for 10 to 30 minutes, as Table 1 shows.

The obtained ruthenium oxide (RuO ₂ ) powder was dispersed together with a glass powder having an average particle diameter of 1.5 μm in a three-roll mill in a vehicle composed of 5% by mass to 15% by mass of ethyl cellulose and 75% by mass to 95% by mass of terpineol. A resist paste was prepared. Glass powder A (PbO: 50 mass%, SiO ₂ : 35 mass%, B ₂ O ₃ : 10 mass%, Al ₂ O ₃ : 5 mass%) was used as the glass powder. In Examples 4 and 7, glass powder B (SiO ₂ : 35 mass%, B ₂ O ₃ : 20 mass%, Al ₂ O ₃ : 5 mass%, CaO: 5 mass%, BaO: 20 mass%, ZnO : 15 mass%). The combination of ruthenium oxide (RuO ₂₎ powder and the glass powder of Example 1-10, the area resistance value of the thick-film resistor formed was adjusted to be about 1 KΩ.

In preparation of the thick film resistance paste, 43 parts by weight of the vehicle was added to 100 parts by weight of the total of the ruthenium oxide (RuO ₂ ) powder and the glass powder. At this time, in addition to Example 10, stearic acid was dispersed in a vehicle with a three-roll mill to prepare a thick film resistance paste. This thick film resistance paste was printed, dried, and baked on an alumina substrate having a purity of 96% by mass to form and evaluate a thick film resistor.

The prepared thick film resistance paste was printed on an electrode of 1% by mass Pd and 99% by mass of Ag which was previously baked on an alumina substrate, dried at 150 ° C for 5 minutes, and then at a peak temperature of 850 ° C for 9 minutes for a total of 30 minutes. It baked and formed the thick film resistor. The thick film resistor was made to have a resistor width of 0.3 mm, a resistor length of 0.3 mm, and a thickness of 10 μm. The evaluation results are shown in Table 1 below.

(Comparative Examples 1 to 7)

In the same manner as in Example 1, an aqueous solution in which potassium ruthenate was dissolved was used as a raw material, and a precipitate of ruthenium oxide was synthesized in an aqueous solution. Next, unlike Example 1, the ruthenium oxide powder after drying was changed in heat treatment conditions in the range of 200 to 850 ° C for 10 to 60 minutes, as shown in Table 2 below.

Then, the thick film resistance paste was prepared like Example 1, the thick film resistor was formed and evaluated. In addition, glass powder A was used in all the comparative examples. The combination of ruthenium oxide (RuO ₂₎ powder and the glass powder Comparative Example 1-5, the area resistance value of the thick-film resistor formed was adjusted to be about 1 KΩ. Further, in addition to Comparative Examples 2 and 5, stearic acid was used to disperse in the vehicle with a three-roll mill to prepare a thick film resist paste.

(Examples 13-18)

In addition to the raw materials used in Examples 1 to 12, silver (Ag) powder having an average particle diameter of 1.0 µm, palladium (Pd) powder and an additive having an average particle diameter of 0.3 µm were used, and in Examples 13 to 18, the area resistance of the thick film resistor formed. The value was adjusted to be approximately 5Ω.

In preparation of the thick film resistance paste, 43 parts by weight of the vehicle was added to 100 parts by weight of the conductive powder of ruthenium oxide (RuO ₂ ) powder, Ag powder, and Pd powder, and the glass powder and the additive powder in total. At this time, stearic acid was dispersed in the vehicle with a three-roll mill to prepare a thick film resist paste. Such thick film resistance pastes were evaluated by printing, drying and baking as in Examples 1 to 12. The evaluation results are shown in Table 3 below.

In Examples 13-18, it evaluated by the same method as Examples 1-12 except having changed the applied voltage of the ESD characteristic of a thick-film resistor into 3 KV.

(Comparative Examples 8-12)

In the same manner as in Comparative Examples 1 to 7, the heat treatment conditions of the obtained ruthenium oxide powder after drying were changed in the range of 200 to 850 ° C for 10 to 60 minutes as shown in Table 4.

Thereafter, as in Examples 13 to 18, in addition to the raw materials used in Examples 1 to 12, silver (Ag) powder having an average particle diameter of 1.0 µm, palladium (Pd) powder having an average particle diameter of 0.3 µm, and additives were used. In Examples 8-12, it adjusted so that the area resistance value of the formed thick film resistor might be set to about 5 ohms. Further, in addition to Comparative Examples 2 and 5, stearic acid was used to disperse in the vehicle with a three-roll mill to prepare a thick film resist paste. These thick film resistance pastes were evaluated by the same method as Comparative Examples 13-18.

<Evaluation>

As shown in the examples of Table 1 and the comparative examples of Table 2, in Examples, since the ruthenium oxide (RuO ₂ ) powder having a specific crystallite diameter and high crystallinity of the present invention was used, the Ru content in the inorganic component was carried out. Except Example 12, it is less than a comparative example. Further, in the embodiment, the value of the current noise is low, and the resistance value change (ESD characteristic) at the time of discharging static electricity is also excellent.

In addition, in the low resistance region in which palladium and silver were added in addition to ruthenium oxide, as shown in the examples of Table 3 and the comparative examples of Table 4, in the examples, the specific crystallite diameter and the high crystallinity of the present invention were oxidized. Since ruthenium (RuO ₂ ) powder was used, it is supposed to reduce the Ru content in the inorganic component. Moreover, the resistance value change (ESD characteristic) at the time of discharge of static electricity is also excellent. Therefore, according to the present invention, it can be seen that it is possible to obtain a thick film resistor composition which is not only economically advantageous by reducing the amount of expensive ruthenium, but also excellent in electrical characteristics.

On the other hand, in Comparative Example because the use of ruthenium oxide missing from the scope of the crystallite size of the present invention, inorganic component content of ruthenium oxide (RuO ₂₎ generally greater than the embodiment of, it was not possible to obtain a desired result.

Claims (12)

Ruthenium oxide (RuO ₂ ) powder having a rutile crystal structure, the crystallite diameter measured by the (110) plane by X-ray diffraction method is 3 to 10 nm, Ru content is characterized in that more than 73% by mass Ruthenium Oxide Powder. The ruthenium oxide powder according to claim 1, wherein the ruthenium oxide (RuO ₂ ) powder has a specific surface area of 70 m ² / g or more and 200 m ² / g or less. The ruthenium oxide powder according to claim 1 or 2, wherein the ruthenium oxide (RuO ₂ ) powder satisfies the following formula 1 with a ratio of crystallite diameter D1 and specific surface area diameter D2:
D1 / D2? (One)
(However, the crystallite diameter D1 is the measured value (nm) in the (110) plane of the rutile crystal structure according to the X-ray diffraction method, and the specific surface area diameter D2 is the specific surface area of the powder S (m ² / g), specific gravity Is a calculated value (nm) of 6 × 10 ⁻⁶ / (ρ · S) when expressed as ρ (g / cm ³ ). The composition for thick film resistors which consisted of the electroconductive particle which consists of the ruthenium oxide powder in any one of Claims 1-3, and glass powder as a main component. The thick film resistor composition according to claim 4, further comprising at least one of silver (Ag) powder, palladium (Pd) powder, or silver powder coated with palladium as an electroconductive particle and at least one of a noble metal powder. . The composition for thick film resistors according to claim 4 or 5, wherein the conductive particles and the glass powder are blended in a mass ratio of 5:95 to 70:30. The composition for thick film resistors according to any one of claims 4 to 6, wherein the glass powder has a 50% cumulative particle size of 5 µm or less. The thick film resistor composition according to any one of claims 4 to 7 is a thick film resistor paste dispersed in an organic vehicle containing a fatty acid, the fatty acid content is 0.1 to 10 parts by weight based on 100 parts by weight of ruthenium oxide. Thick film resistor paste. 9. The thick film resistor paste according to claim 8, wherein the fatty acid is a higher fatty acid having 12 or more carbon atoms. The thick film resistor paste according to claim 8, wherein the conductive particles and the glass powder are blended in a mass ratio of 5:95 to 70:30. The thick film resistor formed by baking the composition for thick film resistors in any one of Claims 4-7 on the ceramic substrate. The thick film resistor formed by baking the thick film resistor paste according to any one of claims 8 to 10 on a ceramic substrate.