JP2019172555A - Composition for thick film resistor, paste for thick film resistor, and thick film resistor - Google Patents

Abstract

An object of the present invention is to provide a composition for a resistor that does not contain a lead component and that can form a thick film resistor having an excellent temperature coefficient of resistance. A composition for a thick-film resistor including a ruthenium oxide powder containing no lead component and a glass containing no lead component, wherein the ruthenium oxide powder has a crystallite calculated from a peak on a (110) plane. The diameter D1 is 25 nm or more and 80 nm or less, the specific surface area diameter D2 is 25 nm or more and 114 nm or less, and the ratio between the crystallite diameter D1 (nm) and the specific surface area diameter D2 (nm) is expressed by the following equation (1). 0.70 ≦ D1 / D2 ≦ 1.00 (1) The glass contains SiO 2, B 2 O 3 and RO (R is at least one element selected from Ca, Sr and Ba), When the total of SiO2, B2O3, and RO is 100 parts by mass, the proportion of SiO2 is 10 to 50 parts by mass, B2O3 is 8 to 30 parts by mass, and RO is 40 to 65 parts by mass. Contained in For thick film resistors. [Selection diagram] None

Description

  The present invention relates to a thick film resistor composition, a thick film resistor paste, and a thick film resistor.

  In general, a thick film resistor such as a chip resistor, a hybrid IC, or a resistor network is formed by printing and baking a paste for a thick film resistor on a ceramic substrate. As a composition for a thick film resistor, a composition mainly composed of ruthenium-based conductive particles represented by ruthenium oxide and glass as conductive particles is widely used.

  The reason why ruthenium-based conductive particles and glass are used for thick film resistors is that they can be fired in air and the temperature coefficient of resistance (TCR) can be brought close to 0, and the resistance value in a wide region can be reduced. For example, a resistor can be formed.

  Here, the temperature coefficient of resistance is a temperature coefficient obtained from resistance values at −55 ° C. and 125 ° C. with respect to a resistance value of 25 ° C., and is obtained by the following equation. The temperature coefficient of resistance obtained from the resistance values of −55 ° C. and 25 ° C. is called the low temperature side TCR (COLD-TCR), and the temperature coefficient of resistance obtained from the resistance values of 25 ° C. and 125 ° C. is the high temperature side TCR (HOT-TCR). That's it.

COLD-TCR (ppm / ° C.) = (R ₋₅₅ −R ₂₅ ) / R ₂₅ / (− 80) × 10 ⁶
HOT-TCR (ppm / ° C.) = (R ₁₂₅ −R ₂₅ ) / R ₂₅ / (100) × 10 ⁶
For thick film resistors, both COLD-TCR and HOT-TCR are required to be close to zero.

Conventionally, ruthenium-based conductive particles most used in thick film resistors include ruthenium oxide (RuO ₂ ) having a rutile crystal structure and lead ruthenate having a pyrochlore crystal structure (Pb ₂ Ru ₂ O _{6). .5} ). These are all oxides showing metallic conductivity.

  As the glass of the thick film resistor, glass having a softening point lower than the firing temperature of the thick film resistor paste is generally used, and glass containing lead oxide (PbO) has been used conventionally. The reason for this is that lead oxide (PbO) has the effect of lowering the softening point of the glass, and the softening point can be changed over a wide range by changing the content, and that a glass with relatively high chemical durability can be made, It can be mentioned that it has high insulation and excellent breakdown voltage.

  In a composition for a thick film resistor containing ruthenium-based conductive particles and glass, if a low resistance value is desired, a large amount of ruthenium-based conductive particles and a small amount of glass are blended. If a high resistance value is desired, ruthenium The resistance value is adjusted by blending a large amount of glass with less conductive particles. In the low resistance region where a large amount of ruthenium-based conductive particles are blended, the temperature coefficient of resistance tends to increase positively, and in the high resistance region where the blending of ruthenium-based conductive particles is small, the resistance temperature coefficient tends to be negative.

  As described above, the temperature coefficient of resistance represents a change in resistance value due to a temperature change, and is one of important characteristics of a thick film resistor. The temperature coefficient of resistance can be adjusted by adding an additive, which is mainly a metal oxide, to the thick film resistor composition. It is relatively easy to adjust the temperature coefficient of resistance to minus, and examples of the additive include manganese oxide, niobium oxide, and titanium oxide. However, it is difficult to adjust the resistance temperature coefficient to plus, and it is practically impossible to adjust the resistance temperature coefficient of a thick film resistor having a minus resistance temperature coefficient to near zero. Therefore, in a region where the resistance temperature coefficient is likely to be negative and the resistance value is high, a combination of conductive particles and glass having a positive resistance temperature coefficient is desirable.

Lead ruthenate (Pb ₂ Ru ₂ O _6.5 ) is characterized by a higher specific resistance than ruthenium oxide (RuO ₂ ) and a higher temperature coefficient of resistance of the thick film resistor. For this reason, lead ruthenate (Pb ₂ Ru ₂ O _6.5 ) has been used as a conductive particle in a region having a high resistance value.

  Thus, the conventional thick film resistor composition contains a lead component in both the conductive particles and the glass. However, the lead component is undesirable from the viewpoint of influence on the human body and pollution, and there is a strong demand for the development of a composition for thick film resistors that does not contain lead.

  Therefore, conventionally, compositions for thick film resistors not containing lead have been proposed (Patent Documents 1 to 5).

  Patent Document 1 includes a resistor paste containing a glass composition containing at least substantially lead and a conductive material having a predetermined average particle diameter substantially free of lead, and these are mixed with an organic vehicle. It is disclosed. Examples of the conductive material include calcium ruthenate, strontium ruthenate, and barium ruthenate.

  According to Patent Document 1, a desired effect is obtained by setting the particle size of the conductive material to be used within a predetermined range and ensuring the substantial particle size of the conductive material excluding the reaction phase. However, the technique disclosed in Patent Document 1 cannot be said to improve the temperature coefficient of resistance. In addition, when conductive particles having a large particle diameter are used, there is a problem that current noise of the formed resistor is large and good load characteristics cannot be obtained.

In Patent Document 2, a glass material is obtained by previously dissolving a first conductive material containing a metal element for imparting conductivity to a glass composition, the glass material, and a second containing the metal element. A process for kneading the conductive material and the vehicle, wherein the glass composition and the first and second conductive materials do not contain lead. Proposed. Then, Ru 2 _O and the like are mentioned as the first and second conductive material. However, there is a problem that the amount of ruthenium oxide dissolved in the glass varies greatly depending on the manufacturing conditions, and the resistance value is not stable.

  Patent Document 3 contains a base solid of (a) a ruthenium-based conductive material and (b) a glass composition not containing lead and cadmium having a predetermined composition, and all of (a) and (b) are organic. A thick film paste composition characterized by being dispersed in a medium has been proposed. As a ruthenium-based conductive material, bismuth ruthenate is cited. However, with this composition, the temperature coefficient of resistance increases to a minus value, and the temperature coefficient of resistance cannot approach 0.

Patent Document 4 discloses a resistor including a ruthenium-based conductive component that does not include a lead component, a glass that does not include a lead component in which the basicity (Po value) of the glass is 0.4 to 0.9, and an organic vehicle. a composition, which MSi ₂ Al ₂ O ₈ crystal thick film resistor to be obtained by firing at high temperatures (M: Ba and / or Sr) resistor composition, characterized in that there is Proposed.
According to Patent Document 4, it is said that the decomposition suppression effect of the ruthenium composite oxide is large because the basicity of the glass is close to the basicity of the ruthenium composite oxide. Further, it is said that a conductive network can be formed by precipitating a predetermined crystal phase in glass.

  However, Patent Document 4 is based on the premise that a ruthenium composite oxide is used as the conductive particles, and the ruthenium oxide that can be obtained industrially more easily than the ruthenium composite oxide has not been specifically studied. Moreover, the influence of the glass composition on the resistance temperature coefficient of the resistor has not been studied.

JP-A-2005-129806 JP 2003-7517 A JP-A-8-253342 JP 2007-103594 A

  In view of the above-described problems of the prior art, an object of one aspect of the present invention is to provide a resistor composition that does not contain a lead component and can form a thick film resistor having an excellent resistance temperature coefficient.

In order to solve the above problems, the present invention
A composition for a thick film resistor comprising ruthenium oxide powder containing no lead component and glass containing no lead,
The ruthenium oxide powder has a crystallite diameter D1 calculated from a peak of (110) plane measured by X-ray diffraction method is 25 nm or more and 80 nm or less,
The specific surface area diameter D2 calculated from the specific surface area is 25 nm or more and 114 nm or less,
And the ratio of the crystallite diameter D1 (nm) and the specific surface area diameter D2 (nm) satisfies the following formula (1),
0.70 ≦ D1 / D2 ≦ 1.00 (1)
The glass contains SiO ₂ , B ₂ O ₃ and RO (R is one or more elements selected from Ca, Sr and Ba), and the total of SiO ₂ , B ₂ O ₃ and RO is 100 mass. Thick film resistor containing 10 parts by mass to 50 parts by mass of SiO ₂ , 8 parts by mass to 30 parts by mass of B ₂ O ₃ , and 40 parts by mass to 65 parts by mass of RO. A composition is provided.

  According to one aspect of the present invention, it is possible to provide a resistor composition that does not contain a lead component and that can form a thick film resistor having an excellent resistance temperature coefficient.

Hereinafter, an embodiment of the composition for a thick film resistor, the paste for the thick film resistor, and the thick film resistor of the present invention will be described.
[Composition for thick film resistor]
The thick film resistor composition of the present embodiment can include ruthenium oxide powder that does not contain a lead component and glass that does not contain a lead component.

  The ruthenium oxide powder has a crystallite diameter D1 calculated from a peak of (110) plane measured by X-ray diffraction method of 25 nm or more and 80 nm or less, and a specific surface area diameter D2 calculated from a specific surface area of 25 nm or more and 114 nm or less. Is preferred.

  Moreover, it is preferable that the ratio between the crystallite diameter D1 (nm) and the specific surface area diameter D2 (nm) satisfies the following formula (1).

0.70 ≦ D1 / D2 ≦ 1.00 (1)
Meanwhile, glass, SiO ₂ and _B 2 _{O 3} and RO (R is Ca, Sr, and one or more elements selected from Ba) may include a. Then, SiO ₂ and _B 2 _{O 3} and RO and is 100 parts by weight of total SiO ₂ 10 parts by mass or more 50 parts by mass or less in _the, B 2 _{O 3} to 8 parts by mass or more than 30 parts by weight, the RO It can contain in the ratio of 40 to 65 mass parts.

  The inventor of the present invention provides a resistor composition comprising a ruthenium oxide powder having a ratio of crystallite diameter to specific surface area diameter within a predetermined range and a glass containing a predetermined component. It was found that the temperature coefficient of resistance of the thick film resistor obtained by firing the composition can be close to 0, and the present invention has been completed. According to the thick film resistor composition of the present embodiment, it is possible to provide a resistor having a resistance temperature coefficient close to 0 even in a resistance value region where ruthenium oxide has a negative resistance temperature coefficient.

Hereinafter, each component included in the present embodiment will be described.
(Ruthenium oxide powder)
In a thick film resistor composition that does not contain lead, it is not possible to use lead ruthenate (Pb ₂ Ru ₂ O _6.5 ), which is a conductive particle having a large resistance temperature coefficient. The combination of conductive powder and glass that is likely to become important is important.

  As described above, it is difficult to adjust the resistance temperature coefficient to a plus even if an additive is used. For this reason, if the temperature coefficient of resistance becomes too negative, it is difficult to adjust to around 0, for example, ± 100 ppm / ° C. However, if the resistance temperature coefficient is positive, the resistance temperature coefficient can be adjusted to around 0 with an additive such as a regulator even if the resistance temperature coefficient is high.

  As the conductive material of the thick film resistor composition not containing lead, a ruthenium oxide powder having a stable resistance value of the thick film resistor obtained by firing the thick film resistor composition is suitable. However, according to the study by the inventors of the present invention, the temperature coefficient of resistance becomes too negative depending on the crystallite diameter of the ruthenium oxide powder and the specific surface area diameter.

  Further, the conductive mechanism of the thick film resistor containing ruthenium oxide powder and glass as main components is the metallic conductivity of the ruthenium oxide powder having a positive resistance temperature coefficient and the ruthenium oxide having a negative resistance temperature coefficient. It is thought to be due to the combination of semiconducting conductivity due to the reaction phase of powder and glass. For this reason, the resistance temperature coefficient tends to be positive in a low resistance value region where the ratio of ruthenium oxide powder is large, and the resistance temperature coefficient tends to be negative in a high resistance value region where the ratio of ruthenium oxide powder is small. Therefore, it is difficult to bring the temperature coefficient of resistance close to 0 in the high resistance value region.

  Therefore, the inventors of the present invention further examined a thick film resistor manufactured using a composition for a thick film resistor containing ruthenium oxide powder and glass. When a thick film resistor is produced using a composition for a thick film resistor containing ruthenium oxide powder and glass, if the crystallite diameter and specific surface area diameter of the ruthenium oxide powder to be used are different, the thick film resistor is used. It has been found that even when the composition of the composition is the same, the area resistance value and resistance temperature coefficient of the thick film resistor obtained are different.

  Based on the above knowledge, the ruthenium oxide powder contained in the thick film resistor composition of the present embodiment has the crystallite diameter D1, the specific surface area diameter D2, and the ratio D1 / D2 between the crystallite diameter and the specific surface area. The predetermined range can be used. By using such ruthenium oxide powder, the resistance temperature coefficient can be made less likely to be negative when a thick film resistor is formed.

  Usually, the primary particle size of ruthenium oxide powder used in thick film resistors is small, so the crystallites are small, the number of crystal lattices that completely satisfy the Bragg condition is reduced, and the diffraction line profile when irradiated with X-rays. Spread. When it is assumed that there is no lattice distortion, if the crystallite diameter is D1 (nm), the X-ray wavelength is λ (nm), the spread of the diffraction line profile on the (110) plane is β, and the diffraction angle is θ, The crystallite diameter can be measured and calculated from the Scherrer equation shown as the equation (2). In calculating the diffraction line profile spread β on the (110) plane, for example, after waveform separation into Kα1 and Kα2, the spread by the optical system of the measuring instrument is corrected, and the half value of the diffraction peak due to Kα1 is corrected. Width can be used.

D1 (nm) = (K · λ) / (β · cos θ) (2)
In the formula (2), K is a Scherrer constant, and 0.9 can be used.

In the case of ruthenium oxide (RuO ₂ ) powder, when the primary particles can be regarded as substantially single crystals, the crystallite diameter measured by the X-ray diffraction method is approximately equal to the particle diameter of the primary particles. For this reason, the crystallite diameter D1 can also be referred to as the primary particle diameter. In ruthenium oxide (RuO ₂ ) having a rutile crystal structure, the diffraction peaks on the (110), (101), (211), (301), and (321) planes of the crystal structure are relatively large among the diffraction peaks. However, the ruthenium oxide powder used in the thick film resistor composition of the present embodiment has the highest relative strength, and the crystallite diameter calculated from the peak of the (110) plane suitable for measurement is as described above. It can be 25 nm or more and 80 nm or less.

On the other hand, the specific surface area increases as the particle size of the ruthenium oxide powder becomes smaller. When the particle diameter of the ruthenium oxide powder is D2 (nm), the density is ρ (g / cm ³ ), the specific surface area is S (m ² / g), and the powder is regarded as a true sphere, the following formula (3) The following relational expression holds. The particle diameter calculated by D2 is defined as the specific surface area diameter.

D2 (nm) = 6 × 10 ³ / (ρ · S) (3)
In this embodiment, the density of ruthenium oxide is 7.05 g / cm ³ , and the specific surface area diameter calculated by the formula (3) can be 25 nm or more and 114 nm or less. The crystallite diameter D1 of the ruthenium oxide powder is 25 nm or more. By doing so, it can be suppressed that the temperature coefficient of resistance of the thick film resistor becomes negative. Further, the withstand voltage characteristic can be improved by setting the crystallite diameter D1 of the ruthenium oxide powder to 80 nm or less.

  Further, when the specific surface area diameter D2 is set to 25 nm or more, when the thick film resistor paste containing the ruthenium oxide powder and the glass powder is baked to produce the thick film resistor using the ruthenium oxide powder, the oxidation is performed. It is possible to prevent the reaction between the ruthenium powder and the glass powder from proceeding excessively. As described above, the reaction temperature phase between the ruthenium oxide powder and the glass powder has a negative temperature coefficient of resistance. For this reason, it is possible to suppress the resistance temperature coefficient of the resulting thick film resistor from becoming negative by suppressing the reaction between the ruthenium oxide powder and the glass powder from proceeding excessively and increasing the proportion of the reaction phase. .

  However, if the specific surface area diameter of the ruthenium oxide powder becomes excessively large, the number of contact points between the ruthenium oxide particles, which are conductive particles, will decrease, and the conductive path will be reduced, resulting in sufficient electrical characteristics such as noise. There is a risk that the characteristics cannot be obtained. For this reason, it is preferable that the specific surface area diameter D2 is 114 nm or less.

  The crystallinity of ruthenium oxide can be increased by setting the ratio D1 / D2 of the crystallite diameter D1 and the specific surface area diameter D2 to 0.70 or more. However, when D1 / D2 exceeds 1.00, coarse particles and fine particles are mixed. By making D1 / D2 0.70 or more and 1.00 or less, it can suppress that the resistance temperature coefficient of the thick film resistor containing the ruthenium oxide becomes negative.

  In addition, as a ruthenium oxide powder used for the composition for thick film resistors of this embodiment, the ruthenium oxide powder which does not contain a lead component is used. The ruthenium oxide powder containing no lead component means that lead is not intentionally added, and means that the content of lead is zero. However, it is not excluded that it is mixed as an impurity component or an unavoidable component in a manufacturing process or the like.

  Next, one structural example of the manufacturing method of the ruthenium oxide powder used for the composition for thick film resistors of this embodiment is demonstrated.

  In addition, since the above-mentioned ruthenium oxide powder can be manufactured with the manufacturing method of the following ruthenium oxide powder, description of some already demonstrated matters is abbreviate | omitted.

  The production method of the ruthenium oxide powder is not particularly limited as long as it can produce the ruthenium oxide powder described above.

  As a method for producing the ruthenium oxide powder, for example, a method of producing the ruthenium oxide hydrate synthesized by wet treatment by heat treatment is desirable. In such a production method, the specific surface area diameter and crystallite diameter can be changed depending on the synthesis method, heat treatment conditions, and the like.

That is, the method for producing ruthenium oxide powder can include, for example, the following steps.
A ruthenium oxide hydrate production step of synthesizing ruthenium oxide hydrate by a wet method.
A ruthenium oxide hydrate recovery step of separating and recovering ruthenium oxide hydrate in the solution.
A drying step of drying ruthenium oxide hydrate.
A heat treatment process for heat-treating ruthenium oxide hydrate.

  In addition, after manufacturing ruthenium oxide having a large particle diameter, which has been generally used in the past, the ruthenium oxide powder manufacturing method in which ruthenium oxide is pulverized is less likely to have a small particle diameter and has a large variation in particle diameter. It is not suitable for the manufacturing method of the ruthenium oxide powder used for the thick film resistor composition of the embodiment.

In the ruthenium oxide hydrate production step, the method for synthesizing the ruthenium oxide hydrate is not particularly limited, and examples thereof include a method of depositing and precipitating ruthenium oxide hydrate in a ruthenium-containing aqueous solution. Specifically, for example, a method of obtaining a ruthenium oxide hydrate starch by adding ethanol to a K ₂ RuO ₄ aqueous solution or a RuCl ₃ aqueous solution neutralized with KOH or the like to obtain a ruthenium oxide hydrate starch. Methods and the like.

  Then, as described above, the ruthenium oxide hydrate recovery step and the drying step separate solid-liquid precipitates of the ruthenium oxide hydrate, wash as necessary, and then dry the ruthenium oxide water. Japanese powder can be obtained.

  The conditions of the heat treatment step are not particularly limited. For example, ruthenium oxide hydrate powder can be made into ruthenium oxide powder having high crystallinity by removing crystal water by heat treatment at a temperature of 400 ° C. or higher in an oxidizing atmosphere. . Here, the oxidizing atmosphere is a gas containing 10% by volume or more of oxygen, and for example, air can be used.

The temperature at which the ruthenium oxide hydrate powder is heat-treated is preferably 400 ° C. or higher as described above, so that a ruthenium oxide (RuO ₂ ) powder having particularly excellent crystallinity can be obtained. The upper limit of the heat treatment temperature is not particularly limited, but the crystallite diameter and specific surface area diameter of the ruthenium oxide powder obtained when the temperature is excessively high are increased, or ruthenium is a hexavalent or octavalent oxide (RuO ₃ or RuO _{3). 4} ) and the rate of volatilization may increase. For this reason, it is preferable to perform heat processing at the temperature of 1000 degrees C or less, for example.

  In particular, the temperature at which the ruthenium oxide hydrate powder is heat-treated is more preferably 500 ° C. or higher and 1000 ° C. or lower.

  As described above, the specific surface area diameter and crystallinity of the obtained ruthenium oxide powder can be changed according to the synthesis conditions for producing ruthenium oxide hydrate, the conditions for heat treatment, and the like. For this reason, for example, it is preferable to select a condition so that a ruthenium oxide powder having a desired crystallite diameter and specific surface area diameter is obtained by conducting a preliminary test or the like.

  The manufacturing method of ruthenium oxide powder can also have arbitrary processes other than the above-mentioned process.

  As described above, the ruthenium oxide hydrate precipitate is solid-liquid separated in the ruthenium oxide hydrate recovery step, dried in the drying step, and then the obtained ruthenium oxide hydrate is machined before the heat treatment step. It is also possible to obtain a crushed ruthenium oxide hydrate powder by crushing (pulverization step).

  Then, the crushed ruthenium oxide hydrate powder is subjected to a heat treatment step, and is heat-treated at a temperature of 400 ° C. or higher in an oxidizing atmosphere, so that the crystal water is removed as described above, and the crystallinity of the ruthenium oxide powder is improved. Can be increased. By performing the crushing process as described above, the degree of aggregation can be suppressed and reduced in the ruthenium oxide hydrate powder to be subjected to the heat treatment process. And the production | generation of the coarse particle and connection particle | grains by heat processing can be suppressed by heat-processing the crushed ruthenium oxide hydrate powder. For this reason, the ruthenium oxide powder provided with the desired crystallite diameter and specific surface area diameter can also be obtained by selecting the conditions in the crushing step.

  In addition, the crushing conditions in a crushing process are not specifically limited, A preliminary test etc. can be selected arbitrarily so that the target ruthenium oxide powder may be obtained.

Moreover, the manufacturing method of a ruthenium oxide powder can also classify the obtained ruthenium oxide powder after a heat treatment process (classification process). By carrying out the classification step in this way, ruthenium oxide powder having a desired specific surface area diameter can be selectively recovered.
(Glass)
The composition for thick film resistors of this embodiment can contain glass (glass powder) that does not contain a lead component. In addition, the glass which does not contain a lead component means that lead is not intentionally added, and means that the content of lead is zero. However, it is not excluded that it is mixed as an impurity component or an unavoidable component in a manufacturing process or the like.

In the glass of a resistor composition that does not contain a lead component, the fluidity at the time of firing can be adjusted by blending a metal oxide other than SiO _{2 serving as} a skeleton. Examples of the metal oxide other than SiO ₂ include B ₂ O ₃ and RO (R represents one or more alkaline earth elements selected from Ca, Sr, and Ba).

In the glass contained in the thick film resistor composition of the present embodiment, when the total of SiO ₂ , B ₂ O ₃ and RO in the glass composition is 100 parts by mass, SiO ₂ is 10 parts by mass or more and 50 parts by mass or less. B ₂ O ₃ is preferably contained in a proportion of 8 parts by mass or more and 30 parts by mass or less, and RO in a proportion of 40 parts by mass or more and 65 parts by mass or less. According to the study of the inventors of the present invention, by using the glass containing each component in such a ratio, the resistance temperature coefficient can be made less likely to be negative when a thick film resistor is formed.

When the total of SiO ₂ , B ₂ O ₃ , and RO in the glass composition is 100 parts by mass, the fluidity can be sufficiently increased by setting the content ratio of SiO ₂ to 50 parts by mass or less. However, since it may become difficult to become glass when the content ratio of SiO ₂ is smaller than 10 parts by mass, it is preferable to contain SiO ₂ at a ratio of 10 parts by mass or more and 50 parts by mass or less.

Further, by the B ₂ O ₃ and 8 parts by mass or more, it is possible to increase the fluidity sufficiently, it is possible to improve the weather resistance by the following 30 parts by weight.

  By making the content rate of RO 40 mass parts or more, it can fully suppress that the resistance temperature coefficient of the obtained thick film resistor becomes minus. Moreover, crystallization can be suppressed and glass can be easily formed by making the content rate of RO 65 mass parts or less.

  According to the study of the inventor of the present invention, a ruthenium oxide powder whose resistance temperature coefficient is unlikely to be negative or a glass whose resistance temperature coefficient is unlikely to be negative alone makes a thick film resistor whose resistance temperature coefficient is close to zero. Is difficult. However, by combining the two, it is possible to make a thick film resistor having a temperature coefficient of resistance close to zero. In the thick film resistor composition of the present embodiment, the thick film resistor using the thick film resistor composition has a resistance temperature even in a resistance region where the area resistance value is higher than 80 kΩ, which has been difficult in the past. The coefficient can be close to 0, and a particularly high effect can be exhibited.

The composition of the glass contained in the thick film resistor composition of the present embodiment is for the purpose of adjusting the weather resistance of the glass and the fluidity during firing in addition to the above-described SiO ₂ , B ₂ O ₃ and RO. Other components can also be contained. Examples of optional additive components include Al ₂ O ₃ , ZrO ₂ , TiO ₂ , SnO ₂ , ZnO, Li ₂ O, Na ₂ O, K ₂ O, etc., one kind selected from these compounds The above can also be added to glass.

Al ₂ O ₃ tends to suppress phase separation of the glass, and ZrO ₂ and TiO ₂ have a function of improving the weather resistance of the glass. SnO ₂ , ZnO, Li ₂ O, Na ₂ O, K ₂ O, and the like have a function of improving the fluidity of the glass.

  A softening point is a measure that affects the fluidity of glass during firing. Generally, the temperature for firing the thick film resistor composition when manufacturing the thick film resistor is 800 ° C. or higher and 900 ° C. or lower.

  Thus, when the firing temperature of the thick film resistor composition when manufacturing the thick film resistor is 800 ° C. or higher and 900 ° C. or lower, the softening of the glass used for the thick film resistor composition according to this embodiment is performed. The point is preferably from 600 ° C. to 800 ° C., more preferably from 600 ° C. to 750 ° C.

  Here, the softening point is the temperature of the differential thermal curve on the lowest temperature side of the differential thermal curve obtained by heating and heating the glass at 10 ° C./min in the atmosphere by differential thermal analysis (TG-DTA). It is the temperature of the peak at which the next differential heat curve on the higher temperature side than the temperature at which the decrease occurs is decreased.

  Generally, glass can be produced by mixing predetermined components or their precursors in accordance with the intended formulation, and melting and quenching the resulting mixture. Although a melting temperature is not specifically limited, For example, it can be set as about 1400 degreeC. Further, the method of rapid cooling is not particularly limited, but it can be carried out by putting the melt in cold water or flowing it on a cold belt.

  A ball mill, a planetary mill, a bead mill or the like can be used for pulverizing the glass, but wet pulverization is desirable for sharpening the particle size.

Although the particle size of the glass is not limited, the 50% volume cumulative particle size of the glass measured by a particle size distribution meter using laser diffraction is preferably 5 μm or less, and more preferably 3 μm or less. If the particle size of the glass is too large, the resistance variation of the thick film resistor increases and the load characteristics deteriorate. On the other hand, if the particle size of the glass is excessively reduced, the productivity is lowered, and there is a possibility that impurities and the like are increased. Therefore, the 50% volume cumulative particle size of the glass is preferably 0.1 μm or more.
(Composition of thick film resistor composition)
The mixing ratio of the ruthenium oxide powder contained in the thick film resistor composition of the present embodiment and glass is not particularly limited. For example, the mixing ratio of ruthenium oxide powder and glass can be changed according to a desired resistance value or the like. The mass of the ruthenium oxide powder: The mass of the glass can be, for example, 5:95 or more and 50:50 or less. That is, it is preferable that the ratio of the ruthenium oxide powder is 5% by mass or more and 50% by mass or less in the ruthenium oxide powder and the glass.

  This is because when the total of the ruthenium oxide powder and glass contained in the thick film resistor composition of the present embodiment is 100 mass%, the thickness obtained is less than 5 mass%. This is because the resistance value of the film resistor may become too high and become unstable.

  Moreover, when the sum total of the ruthenium oxide powder and glass which the composition for thick film resistors of this embodiment contains is 100 mass%, it is obtained by making the ratio of ruthenium oxide powder 50 mass% or less. This is because the strength of the thick film resistor can be made sufficiently high and brittleness can be particularly reliably prevented.

  The mixing ratio of the ruthenium oxide powder and the glass in the thick film resistor composition of the present embodiment is more preferably in the range of the mass of the ruthenium oxide powder: the mass of the glass = 5: 95 to 40:60. preferable. That is, it is more preferable that the ruthenium oxide powder ratio in the ruthenium oxide powder and the glass is 5% by mass or more and 40% by mass or less.

  In addition, it is preferable that the composition for thick film resistors of this embodiment contains the above-mentioned ruthenium oxide powder and glass as a main component, and can also be comprised only from a ruthenium oxide powder and glass. The thick film resistor composition of the present embodiment preferably contains the aforementioned mixed powder of ruthenium oxide powder and glass in a proportion of, for example, 80% by mass or more and 100% by mass or less, and 85% by mass or more and 100%. It is more preferable to contain in the ratio of the mass% or less.

  The thick film resistor composition of the present embodiment can further contain an optional component as necessary.

An additive generally used for the purpose of improving and adjusting the resistance value, resistance temperature coefficient, load characteristics, trimming property, and the like of the resistor may be added to the resistor composition of the present embodiment. Typical additives include Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , CuO, MnO ₂ , ZrO ₂ , Al ₂ O ₃ , SiO ₂ , ZrSiO _{4 and the} like. By adding these additives, it is possible to create a resistor having more excellent characteristics. The amount to be added is adjusted depending on the purpose, but is preferably 20 parts by mass or less with respect to 100 parts by mass in total of the ruthenium oxide powder and the glass.

Note that these components may not be added. That is, the thick film resistor composition of the present embodiment can also be composed of ruthenium oxide powder and glass. For this reason, these additives can be added so that it may become 0 or more with respect to a total of 100 mass parts of ruthenium oxide powder and glass.
[Thick film resistor paste]
One structural example of the thick film resistor paste of this embodiment will be described.

  The thick film resistor paste of the present embodiment can include the thick film resistor composition and the organic vehicle described above. The thick film resistor paste of the present embodiment preferably has a structure in which the above-described thick film resistor composition is dispersed in an organic vehicle.

  As described above, the thick film resistor paste of the present embodiment is used for a thick film resistor by dispersing the above-described thick film resistor composition in a solvent in which a resin component called an organic vehicle is dissolved. It can be a paste.

  There are no particular limitations on the type and composition of the organic vehicle resin or solvent. As the resin component of the organic vehicle, for example, one or more selected from ethyl cellulose, acrylic acid ester, methacrylic acid ester, rosin, maleic acid ester and the like can be used.

  As the solvent, for example, one or more selected from terpineol, butyl carbitol, butyl carbitol acetate and the like can be used. For the purpose of delaying the drying of the thick film resistor paste, a solvent having a high boiling point may be added. Moreover, a dispersing agent, a plasticizer, etc. can also be added as needed.

  The compounding ratio of the resin component and the solvent can be adjusted according to the viscosity required for the obtained thick film resistor paste. The ratio of the organic vehicle to the thick film resistor composition is not particularly limited, but when the thick film resistor composition is 100 parts by mass, the ratio of the organic vehicle is, for example, 20 parts by mass or more and 200 parts by mass or less. can do.

  The method for producing the thick film resistor paste of the present embodiment is not particularly limited. For example, the thick film described above is used by using one or more types selected from a three roll mill (three roll mill), a planetary mill, a bead mill, and the like. The resistor composition can also be dispersed in an organic vehicle. Further, for example, the above-described thick film resistor composition can be mixed in a ball mill or a crushing machine and then dispersed in an organic 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, that is, in an organic vehicle. In general, when the particle size of the powder becomes smaller, the aggregation becomes stronger and it becomes easier to form secondary particles. For this reason, in the thick film resistor paste of the present embodiment, fatty acid or the like can also be added as a dispersant in order to make it easy to break up the secondary particles and disperse them in the primary particles.
[Thick film resistor]
A configuration example of the thick film resistor according to this embodiment will be described.

  The thick film resistor of this embodiment can be manufactured using the thick film resistor composition and the thick film resistor paste described above. For this reason, the thick film resistor of this embodiment can contain the composition for thick film resistors as described above, and can contain the ruthenium oxide powder as described above and a glass component.

  As described above, in the thick film resistor composition, the ruthenium oxide powder ratio in the ruthenium oxide powder and the glass is preferably 5% by mass or more and 50% by mass or less. And the thick film resistor of this embodiment can be manufactured using this composition for thick film resistors, and the glass component in the thick film resistor obtained is derived from the glass of the composition for thick film resistors. For this reason, the thick film resistor of the present embodiment has a ruthenium oxide powder ratio of 5 mass% or more and 50 mass% or less of the ruthenium oxide powder and the glass component in the same manner as the thick film resistor composition. It is preferable that it is 5 mass% or more and 40 mass% or less.

  Although the manufacturing method of the thick film resistor of this embodiment is not specifically limited, For example, the composition for thick film resistors mentioned above can be baked and formed on a ceramic substrate. Alternatively, the above-described thick film resistor paste can be applied to a ceramic substrate and then fired.

Specific examples and comparative examples will be described below, but the present invention is not limited to these examples.
(Evaluation methods)
First, an evaluation method of the ruthenium oxide powder used in the following examples and comparative examples will be described.
1. Evaluation of Ruthenium Oxide Powder In order to evaluate the shape and physical properties of the ruthenium oxide powder, calculation of the crystallite diameter by the X-ray diffraction method and calculation of the specific surface area diameter by the BET method were performed.
(1) Crystallite diameter The crystallite diameter can be calculated from the peak broadening of the X-ray diffraction pattern. Here, the peak of the rutile structure obtained by X-ray diffraction is waveform-separated into Kα1 and Kα2, and then the half width is measured as the broadening of the peak of Kα1 corrected by the optical system of the measuring instrument. Calculated from

  Specifically, when the crystallite diameter is D1 (nm), the X-ray wavelength is λ (nm), the diffraction line profile spread is β, and the diffraction angle is θ, the following expression (2) is shown. The crystallite size was calculated from the Scherrer equation.

D1 (nm) = (K · λ) / (β · cos θ) (2)
In Equation (2), K is a Scherrer constant, and 0.9 can be used.
(2) Specific surface area diameter The specific surface area diameter can be calculated from the specific surface area and the density. For the specific surface area, a BET one-point method that allows easy measurement was used. When the specific surface area diameter is D2 (nm), the density is ρ (g / cm ³ ), the specific surface area is S (m ² / g), and the powder is regarded as a true sphere, the following relational expression (3) is obtained. It holds. The particle diameter calculated by D2 is defined as the specific surface area diameter.

D2 (nm) = 6 × 10 ³ / (ρ · S) (3)
In this embodiment, the density of ruthenium oxide is 7.05 g / cm ³ .
2. Evaluation of Glass Glass powders A to H were prepared, and compositions for thick film resistors and the like were prepared in Examples and Comparative Examples described later.
(50% volume cumulative particle size)
All the glass powders were pulverized by a ball mill so that the 50% volume cumulative particle size was 1.3 μm or more and 1.5 μm or less. Here, the 50% volume cumulative particle size was measured by a particle size distribution meter using laser diffraction.
(Softening point)
The softening point of the glass powder is the decrease in the differential thermal curve on the lowest temperature side of the differential thermal curve obtained by heating and heating the glass powder at 10 ° C. per minute in the atmosphere by differential thermal analysis (TG-DTA). The temperature of the peak at which the next differential heat curve on the higher temperature side than the temperature at which the temperature appears is reduced.
3. Evaluation of Thick Film Resistor About the obtained thick film resistor, film thickness, sheet resistance value, resistance temperature coefficient from 25 ° C. to −55 ° C. (COLD-TCR), resistance temperature coefficient from 25 ° C. to 125 ° C. ( HOT-TCR) was evaluated. In Table 1, COLD-TCR is described as C-TCR and HOT-TCR is described as H-TCR.
(1) Film thickness The film thickness was measured with a stylus thickness roughness meter (model number: Surfcom 480B, manufactured by Tokyo Seimitsu Co., Ltd.) for five thick film resistors prepared in the same manner in each example and comparative example. It was calculated by measuring the thickness and averaging the measured values.
(2) Area resistance value In addition, the area resistance value was measured with a digital multimeter (No. 2001, manufactured by KEITHLEY) for the resistance values of 25 thick film resistors prepared in the same manner in each of the examples and comparative examples. Calculated by averaging the values.
(3) Resistance temperature coefficient In measuring the temperature coefficient of resistance, the five thick film resistors prepared in the same manner in each of the examples and comparative examples were held at -55 ° C, 25 ° C, and 125 ° C for 15 minutes, respectively. Then, the resistance value was measured, the resistance value at −55 ° C. was R ₋₅₅ , the resistance value at 25 ° C. was R ₂₅ , and the resistance value at 125 ° C. was R ₁₂₅ . And the resistance temperature coefficient in each temperature range was calculated about each thick film resistor by the following formula | equation (4) and Formula (5). Next, the average of the five thick film resistors of the resistance temperature coefficient in each calculated temperature range was calculated, and the resistance temperature coefficient in each temperature range of the thick film resistors obtained in each Example and Comparative Example ( COLD-TCR and HOT-TCR). In either case, the unit is ppm / ° C. It is desirable that the temperature coefficient of resistance is close to 0, and a resistance temperature coefficient ≦ ± 100 ppm / ° C. is regarded as an indication of an excellent resistor.

COLD-TCR = (R− ₅₅₋ R ₂₅ ) / R ₂₅ / (− 80) × 10 ⁶ (4)
HOT-TCR = (R ₁₂₅ -R ₂₅ ) / R ₂₅ / (100) × 10 ⁶ (5)
[Example 1]
As shown in Table 1, 18 parts by mass of ruthenium oxide powder a and 82 parts by mass of glass powder A were mixed to prepare a thick film resistor composition. The ratio of the ruthenium oxide particles to the glass powder was adjusted so that the area resistance value of the obtained thick film resistor was about 100 kΩ. The characteristics of the ruthenium oxide powder a and the components contained in the glass powder A are shown in Tables 2 and 3, respectively.

  Then, 100 parts by mass of the thick film resistor composition and 43 parts by mass of the organic vehicle are kneaded by a three roll mill, and the thick film resistor composition is dispersed in the organic vehicle to obtain a thick film resistor paste. Produced.

  The produced thick film resistor paste was printed on an electrode containing 1% by mass of Pd and 99% by mass of Ag previously formed by firing on an alumina substrate. Next, after drying at 150 ° C. for 5 minutes, a thick film resistor was formed by firing at a peak temperature of 850 ° C. for 9 minutes and a total of 30 minutes including the temperature rise time and the temperature fall time. The size of the thick film resistor was such that the resistor width was 1.0 mm and the resistor length (between electrodes) was 1.0 mm.

The obtained thick film resistor was evaluated. The results are shown in Table 1.
[Example 2 to Example 12]
A thick film resistor composition was prepared in the same manner as in Example 1 except that the ruthenium oxide powder and glass powder shown in Table 1 were mixed at the ratio shown in Table 1 to prepare a thick film resistor composition. A composition for a film resistor, a paste for a thick film resistor, and a thick film resistor were prepared.

  The characteristics of each ruthenium oxide powder and each component contained in the glass powder are shown in Tables 2 and 3, respectively.

In Examples 11 and 12, when preparing the thick film resistor composition, TiO ₂ and Nb ₂ O ₅ were added in addition to the ruthenium oxide powder and the glass powder as shown in Table 1.

The evaluation results of the obtained thick film resistor are shown in Table 1.
[Comparative Examples 1 to 9]
A thick film resistor composition was prepared in the same manner as in Example 1 except that the ruthenium oxide powder and glass powder shown in Table 1 were mixed at the ratio shown in Table 1 to prepare a thick film resistor composition. A composition for a film resistor, a paste for a thick film resistor, and a thick film resistor were prepared.

  The characteristics of each ruthenium oxide powder and each component contained in the glass powder are shown in Tables 2 and 3, respectively.

  The evaluation results of the obtained thick film resistor are shown in Table 1.

表１に示した結果によると、実施例２〜実施例１２は、抵抗温度係数が±１００ｐｐｍ／℃以内となっており、優れた抵抗体を得られることが確認できた。

According to the results shown in Table 1, in Examples 2 to 12, the temperature coefficient of resistance was within ± 100 ppm / ° C., and it was confirmed that an excellent resistor could be obtained.

In Example 1, the H-TCR of the temperature coefficient of resistance exceeds 100 ppm / ° C, but it is easy to adjust the temperature coefficient of resistance to minus by using an additive. For example, as shown in Examples 11 and 12, by adding TiO ₂ and Nb ₂ O ₅ to the thick film resistor composition of Example 1, the resistance temperature coefficient can be adjusted to within ± 100 ppm / ° C. It could be confirmed.

On the other hand, in Comparative Examples 1 to 9, it was confirmed that the temperature coefficient of resistance was more negative than −100 ppm / ° C. For this reason, even if additives such as TiO ₂ and Nb ₂ O ₅ are added, it cannot be adjusted to ± 100 ppm / ° C.

  As can be seen from the above Examples and Comparative Examples, the temperature coefficient of resistance of the thick film resistor using the composition for the thick film resistor containing ruthenium oxide powder not containing a lead component and glass, which has been difficult in the past. Was easily adjusted within ± 100 ppm / ° C., and it was confirmed that an excellent thick film resistor could be formed.

Claims (5)

A composition for a thick film resistor comprising ruthenium oxide powder containing no lead component and glass containing no lead component,
The ruthenium oxide powder has a crystallite diameter D1 calculated from a peak of (110) plane measured by X-ray diffraction method is 25 nm or more and 80 nm or less,
The specific surface area diameter D2 calculated from the specific surface area is 25 nm or more and 114 nm or less,
And the ratio of the crystallite diameter D1 (nm) and the specific surface area diameter D2 (nm) satisfies the following formula (1),
0.70 ≦ D1 / D2 ≦ 1.00 (1)
The glass contains SiO ₂ , B ₂ O ₃ and RO (R is one or more elements selected from Ca, Sr and Ba), and the total of SiO ₂ , B ₂ O ₃ and RO is 100. Thick film resistor containing SiO ₂ in a proportion of 10 to 50 parts by mass, B ₂ O ₃ in an amount of 8 to 30 parts by mass, and RO in a proportion of 40 to 65 parts by mass when it is defined as parts by mass. Body composition.   The composition for thick film resistors according to claim 1, wherein a ratio of the ruthenium oxide powder in the ruthenium oxide powder and the glass is 5% by mass or more and 50% by mass or less.   The composition for thick film resistors according to claim 1, wherein the glass has a 50% volume cumulative particle size of 5 μm or less.   A thick film resistor paste comprising the thick film resistor composition according to any one of claims 1 to 3 and an organic vehicle.   The thick film resistor containing the composition for thick film resistors as described in any one of Claims 1-3.