JP2018198259A - Composition for negative characteristic resistor, resistance paste for negative characteristic resistor, and negative characteristic thermistor - Google Patents

Abstract

To provide a composition for a negative characteristic resistor, a resistive paste for a negative characteristic resistor, and a negative characteristic thermistor which do not contain a lead component and are excellent in negative temperature coefficient of resistance with small variations in resistance values.SOLUTION: In a composition for a negative characteristic resistor containing conductive particles and glass frit, which is a raw material of a negative characteristic thermistor, the conductive particles are represented by the general formula: BiRuNbO(0.06≤x≤0.50), and the content of Pb in the glass frit is less than 0.1% by mass.SELECTED DRAWING: None

Description

  The present invention relates to a negative characteristic resistor composition, a negative characteristic resistor resistive paste, and a negative characteristic thermistor using the negative characteristic resistor resistive paste. More specifically, a negative characteristic resistor composition used to form a lead-free thick film type negative characteristic thermistor on a ceramic substrate, a negative characteristic resistor resistive paste, and the negative characteristic resistor The present invention relates to a thick film negative characteristic thermistor using a resistance paste.

  The thermistor is a resistor whose resistance value changes greatly according to temperature change, and is an electronic component widely applied to temperature detection, temperature control, a self-temperature control heater, a power meter, and the like. The thermistor is classified into a negative characteristic thermistor (NTC thermistor, CTR thermistor) whose resistance value decreases as the temperature increases, and a positive characteristic thermistor (PTC thermistor) whose resistance value increases as the temperature increases. Of these, NTC thermistors, which are negative characteristic thermistors, are most commonly used. Thermistors can take various shapes such as disk type, thin film type, and thick film type. Of these, the thick film type thermistor applies a paste containing conductive particles and glass frit to an insulating ceramic substrate. It is manufactured by firing and has the advantage of being small and inexpensive.

Japanese Patent Application Laid-Open No. 08-253342 describes a resistor composition comprising a Ru (ruthenium) -based conductive material and a glass frit containing Bi ₂ O ₃ as a resistor composition that does not contain lead. ing. However, in recent years, as electronic components have been miniaturized, it has been required to improve the accuracy of electrical characteristics, and the demand is no exception for thermistors. From the viewpoint of regulating resistance value variations and current noise in such a thermistor, the resistor composition described in Japanese Patent Application Laid-Open No. 08-253342 sufficiently satisfies the required characteristics. I can't.

Japanese Patent Application Laid-Open No. 2008-192784 discloses at least one ruthenium selected from Y ₂ Ru ₂ O ₇ , Nd ₂ Ru ₂ O ₇ , Sm ₂ Ru ₂ O ₇ , and Gd ₂ Ru ₂ O _7. A composition comprising system conductive particles and glass frit containing no lead and Bi ₂ O ₃ is described. However, in recent years, there has been a demand for higher electrical response speed as well as downsizing of electronic components. From this viewpoint, the negative temperature in the thermistor obtained by using the composition described in Japanese Patent Application Laid-Open No. 2008-192784. There is a demand for a negative temperature coefficient thermistor having a negative temperature characteristic larger than the characteristic.

JP 08-253342 A JP 2008-192784 A

  As described above, various negative resistor thermistor compositions and resistor pastes using conductive particles and lead-free glass powder have been disclosed. Resistor compositions and resistor pastes having sufficiently satisfactory characteristics for accuracy have not been mass-produced.

  The present invention has been made in view of such circumstances, and has a small variation in resistance value, an excellent negative resistance temperature coefficient, a composition for negative characteristic resistors that does not contain a lead component, and for negative characteristic resistors The object is to provide a resistance paste and a negative thermistor.

As a result of intensive studies, the present inventor has found that in a composition for negative characteristic resistor containing conductive particles and glass frit, Bi ₂ Ru ₂ O _{7 in} which Ru is partially substituted with Nb as the conductive particles. And using the powder, that is, particles made of a ruthenium niobium-containing composite oxide powder represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50), and the glass frit When the Pb content is less than 0.1% by mass, the resistance value variation is small, the negative temperature coefficient of resistance is excellent, the composition for negative characteristic resistors not containing a lead component, the resistance paste, and The inventors have found that a negative characteristic thermistor can be obtained, and have reached the present invention.

That is, the negative characteristic resistor composition of the present invention is composed of a ruthenium niobium-containing composite oxide powder represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50). And the Pb content in the glass frit is less than 0.1% by mass. The range of the value of x indicating the Nb content in the general formula is preferably 0.10 ≦ x ≦ 0.40.

The glass frit is made of Si—B—Al—Ba—Zn—O-based glass powder containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO, and B ₂ in the glass powder. the content of O ₃ is preferably in the range of 14 to 25 mass%.

  The mass ratio of the ruthenium niobium-containing composite oxide powder and the glass frit is preferably in the range of 25:75 to 65:35.

  The negative characteristic resistor resistor paste of the present invention comprises a negative characteristic resistor composition and an organic vehicle, and the negative characteristic resistor composition comprises the negative characteristic resistor composition of the present invention, The negative characteristic resistor composition is dispersed in the organic vehicle.

The negative characteristic thermistor of the present invention has a ceramic substrate and a thick film negative characteristic resistor provided on the ceramic substrate, and the thick film negative characteristic resistor comprises a conductor component and a caking agent. The composition of the conductor component is represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50), and the content of Pb in the binder is 0. Less than 1% by mass. The range of the value of x indicating the Nb content in the general formula is preferably 0.10 ≦ x ≦ 0.40.

The caking agent is made of Si—B—Al—Ba—Zn—O-based glass containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO, and B in the glass The content of ₂ O ₃ is preferably in the range of 14% by mass to 25% by mass.

  The negative characteristic thermistor manufactured using the composition for negative characteristic resistor of the present invention has a small variation in resistance value, an excellent negative temperature coefficient of resistance, and is substantially free of Pb. In recent years, the negative characteristic thermistor has sufficiently satisfactory characteristics for miniaturization and high accuracy.

(1) Composition for negative characteristic resistor In the present invention, a ruthenium niobium-containing composite oxide powder represented by a general formula: Bi ₂ Ru _2-x Nb _x O ₇ and a glass frit are used. By using the main component of the resistor, the fact that the resistance temperature coefficient of the resistor obtained by firing the resistor paste containing the composition for negative characteristic resistor greatly becomes negative is utilized.

(A) Conductive Particles In the composition for negative characteristic resistor of the present invention, the conductive particles are represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50). It is comprised by the ruthenium niobium containing complex oxide powder. The range of the value of x indicating the Nb content is preferably 0.10 ≦ x ≦ 0.40.

As the ruthenium niobium-containing composite oxide powder, powders obtained by various production methods can be used. For example, it can be produced by replacing a part of Ru in Bi ₂ Ru ₂ O ₇ with Nb. Specifically, it can be produced by a method in which powders of Nb ₂ O ₅ , RuO ₂ and Bi ₂ O ₃ are mixed, baked and then pulverized.

  The range of x indicating the Nb content is 0.06 ≦ x ≦ 0.50. That is, the molar ratio of Nb: Ru ranges from 3:97 to 25:75. If the value of x is smaller than 0.06, the expected sufficient thermistor characteristics cannot be obtained. On the other hand, even if the value of x is made larger than 0.50, Ru is not replaced with Nb any more, and the remaining Nb adversely deteriorates the thermistor characteristics. The value range of x indicating the Nb content is preferably 0.10 ≦ x ≦ 0.40.

  The conductive particles are not limited by the particle size, but the average particle size of the conductive particles is preferably 0.1 μm or less, and more preferably in the range of 0.01 μm to 0.08 μm. . By controlling the average particle size of the conductive particles to 0.1 μm or less, in the negative characteristic thermistor manufactured using the negative characteristic resistor composition using the conductive particles, the resistance value variation and voltage It becomes possible to suppress deterioration due to the load. The lower limit value of the conductive particles is not limited, but usually the lower limit value of the average particle diameter of the conductive particles is about 0.01 μm.

(B) Glass frit A glass frit is softened by firing to form a thick film while bonding conductive particles, and as a caking agent that adheres the thick film to a substrate such as a ceramic substrate. Take on the function.

  In the present invention, the glass frit constituting the composition for negative characteristic resistors is not particularly limited to the composition as long as the Pb content is 0.1% by mass or less.

Preferably, the glass frit of the present invention is made of Si—B—Al—Ba—Zn—O-based glass powder containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO as main components. Composed. By configuring the glass frit with the glass powder having such a composition, it is possible to suppress deterioration due to moisture or voltage load in the finally obtained thermistor.

In the glass frit having this composition, the content of B ₂ O ₃ in the glass frit is preferably in the range of 14% by mass to 25% by mass, and more preferably in the range of 14% by mass to 20% by mass. . If the B ₂ O ₃ content is 14 wt% or more, the thermistor characteristic becomes better. However, if the content of B ₂ O ₃ exceeds 25% by mass, the water resistance and weather resistance of the glass deteriorate.

  From the viewpoint of suppressing deterioration due to moisture or voltage load in the thermistor, it is desirable that the glass frit does not contain an alkali metal component.

  The average particle size of the glass frit is desirably 5.0 μm or less, and more desirably in the range of 0.5 μm to 3.0 μm. By setting the average particle size of the glass frit to 5.0 μm or less, it is possible to suppress variations in resistance value of the thermistor finally obtained and deterioration due to voltage load. The lower limit value of the average particle size of the glass frit is not limited, but since the glass frit is obtained by pulverizing raw materials using a ball mill, a bead mill or the like, the lower limit value of the average particle size of the glass frit is usually used. Is about 0.5 μm.

In the composition for negative characteristic resistor of the present invention, in addition to conductive particles and glass frit, various additives and dispersions conventionally used for adjusting the electrical characteristics of the thermistor finally obtained. It is possible to contain an agent, a plasticizer and the like. That is, the composition for negative characteristic resistors of the present invention may contain additives for the purpose of adjusting the sheet resistance value and the temperature coefficient of resistance, adjusting the expansion coefficient, improving the voltage resistance, and other modifications. it can. Examples of such additives include 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. The content of these additives is about 0.05% by mass to 20% by mass with respect to the total mass of the conductive particles and the glass frit.

(C) Mixing ratio of conductive particles and glass frit The mixing ratio of conductive particles, that is, ruthenium niobium-containing composite oxide powder and glass frit is in a range of 25:75 to 65:35 in terms of mass ratio. It is preferable that it is in the range of 25:75 to 50:50. That is, the compounding ratio of the conductive particles is in the range of 25% to 65% by mass, preferably in the range of 25% to 50% by mass, and the compounding ratio of the glass frit is in the range of 35% to 75% by mass. Preferably, it is the range of 50 mass%-75 mass%.

  When a resistive paste for negative characteristic resistors is printed and fired using ruthenium niobium-containing composite oxide powder as conductive particles, the conductive particles themselves are sintered because the resistor is formed by sintering glass frit. Never do. For this reason, when the content of the ruthenium niobium-containing composite oxide powder exceeds 65% by mass with respect to the total mass of the conductive particles and the glass frit, cracks and the like occur in the resistor during firing, and the final result In the thermistor obtained in (1), there may be a large variation in resistance value.

  On the other hand, the ruthenium niobium-containing composite oxide powder has a higher specific resistance of the conductive particles itself due to substitution of part of Ru with Nb, so the content of the ruthenium niobium-containing composite oxide powder is If the amount is less than 25% by mass with respect to the total mass of the conductive particles and the glass frit, the resistance value of the thermistor may become too high.

(2) Negative Characteristic Resistor Resistive Paste The negative characteristic resistor resistive paste of the present invention is composed of a negative characteristic resistor composition and an organic vehicle. The negative characteristic resistor composition of the present invention is used. In the negative characteristic resistor paste, the negative characteristic resistor composition is dispersed in an organic vehicle.

  The organic vehicle has a function of making conductive particles and glass frit constituting the resistor composition into a paste suitable for printing. As an organic vehicle, the material generally used for resistance paste can be used. For example, a resin obtained by dissolving a resin such as ethyl cellulose, butyral, or acrylic in a solvent such as terpineol, butyl carbitol, or butyl carbitol acetate is used.

  The resistance paste for negative characteristic resistors is not limited by the blending amount of the organic vehicle, but when the blending amount of the composition for negative characteristic resistors is 100 parts by mass, the blending amount of the organic vehicle is It is preferably 15 parts by mass or more. When the blending amount of the organic vehicle is less than 15 parts by mass, the viscosity of the negative characteristic resistor paste becomes too high, and printing may not be possible. The amount of the organic vehicle is preferably 20 parts by mass or more, and more preferably 30 parts by mass or more. However, since the volatility at the time of firing is impaired, the upper limit of the amount of the organic vehicle is about 100 parts by mass.

  Further, the method for producing the resistance paste for negative characteristic resistor of the present invention is not particularly limited, and generally used when producing a resistance paste, using a roll mill, a ball mill, a bead mill, etc. The paste for negative characteristic resistors can be obtained by pulverizing and dispersing various materials containing the composition for negative characteristic resistors in an organic vehicle.

(3) Negative characteristic thermistor The negative characteristic thermistor of this invention has a ceramic substrate and the thick film negative characteristic resistor provided on this ceramic substrate. This thick film negative characteristic resistor is obtained by applying a negative characteristic resistor paste containing a negative characteristic resistor composition to a ceramic substrate and firing at a temperature in the range of 750 ° C. to 900 ° C. in an oxidizing atmosphere. It is formed by doing.

This thick film negative characteristic resistor comprises a conductor component and a caking agent, and each composition corresponds to the composition of conductive particles and glass frit in the negative characteristic resistor composition. That is, in the negative characteristic thermistor of the present invention, the composition of the conductor component is represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50), and The content of Pb in the binder is less than 0.1% by mass. In addition, it is preferable that the range of the value of x which shows content of Nb in general formula is 0.10 <= x <= 0.40.

The caking agent is made of Si—B—Al—Ba—Zn—O-based glass containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO, and this glass The content of B ₂ O ₃ in is preferably in the range of 14% by mass to 25% by mass.

  The film thickness of the thick film negative characteristic resistor constituting the negative characteristic thermistor of the present invention is arbitrary, and the present invention is not limited by this film thickness. Therefore, the average film thickness of the thick film negative characteristic resistor involved in the characteristics of the negative characteristic thermistor can be 5 μm or less, or an average film thickness exceeding this can be adopted. Furthermore, a thick film negative characteristic resistor having an average film thickness of 10 μm or more is also within the scope of the present invention.

  Since the negative characteristic thermistor of the present invention has a small variation in resistance value and an excellent negative resistance temperature coefficient, the thermistor has sufficient thermistor characteristics to satisfy the miniaturization and high accuracy of the negative characteristic thermistor. ing. Specifically, the converted area resistance value, which is the resistance value when the film thickness is 7 μm, is in the range of 100Ω / □ to 10 MΩ / □, and the variation in resistance value is less than 5% in this region. And a negative temperature coefficient of resistance is a temperature coefficient of resistance (COLD-TCR: hereinafter referred to as “C-TCR”) from 25 ° C. to −55 ° C., and is −2000 ppm / ° C. or lower, and 25 ° C. to 125 ° C. The temperature coefficient of resistance up to ℃ (HOT-TCR: hereinafter referred to as “H-TCR”) is −1000 ppm / ° C. or less. Note that the variation in resistance value is preferably 4% or less, and more preferably 3% or less.

  Hereinafter, the present invention will be described more specifically using examples thereof. However, the present invention is not limited to these examples.

First, K ₂ RuO ₄ obtained by alkali-melting Ru was dissolved in pure water, ethanol was added, and then washed with water and dried to obtain Ru hydrated oxide. The hydrated oxide of Ru, Nb ₂ O ₅ powder, and Bi ₂ O ₃ powder are mixed at a predetermined ratio and roasted at 800 ° C. for 5 hours to obtain a general formula: Bi ₂ Ru _2-x A ruthenium niobium-containing composite oxide powder represented by Nb _x O ₇ was synthesized.

  The obtained ruthenium niobium-containing composite oxide powder was pulverized with a ball mill for 24 hours and then dried at 200 ° C. for 24 hours to obtain a fine ruthenium niobium-containing composite oxide powder.

Table 1 shows the mixing ratio of the hydrated oxide of Ru, the Nb ₂ O ₅ powder, and the Bi ₂ O ₃ powder in terms of the molar ratio of each metal element. The average particle diameter of the obtained conductive particles (ruthenium niobium-containing composite oxide powder) was in the range of 50 nm to 60 nm. The specific surface area of the conductive particles was in the range of ^{10m 2} / ^g~12m 2 / g.

  Two types of glass frit were prepared as the glass frit for evaluation of the present invention. Table 2 shows the composition of the two types of prepared glass frit. The average particle size of the glass frit was in the range of 1 μm to 2 μm.

  A ruthenium niobium-containing composite oxide powder shown in Table 1, a glass frit shown in Table 2, and an organic vehicle mainly composed of ethyl cellulose and terpineol were kneaded using a three-roll mill, and various resistances for negative characteristic resistors. The paste was produced and it was set as Examples 1-8 and Comparative Examples 1 and 2. Table 3 shows the composition of the prepared resistance paste.

  The produced resistance paste was screen-printed with a width of 1.0 mm between Ag electrodes previously formed on an alumina substrate at intervals of 1.0 mm, then dried at 150 ° C. for 10 minutes, and then a peak temperature of 850 ° C. and a peak time. Firing was performed using a belt furnace set to 9 minutes. By adjusting the thickness of the resistance paste, the thickness of the thick film negative characteristic resistor in the obtained negative characteristic thermistor was adjusted. As a result, the average film thickness of the thick film negative characteristic resistor was about 7 μm.

  About the thick film negative characteristic resistor which comprises the obtained negative characteristic thermistor, about Examples 1-8 and Comparative Examples 1 and 2, the film thickness and resistance value were measured, respectively, and the baking film thickness was 7 micrometers. The converted area resistance value, variation in resistance value, C-TCR and H-TCR were calculated.

  Hereinafter, each measurement method and calculation method will be described.

  The film thickness was measured using a stylus type surface roughness / contour shape measuring instrument, and the average value of the film thickness measurement values of each of the five thick film negative characteristic resistors was taken as the “measured film thickness” and converted as follows: It used for calculation of sheet resistance.

  The resistance value was measured by the four-terminal method, and the variation of the resistance value was calculated using the measured value of the resistance value of the 25 thick film negative characteristic resistors. Furthermore, the average value of the measured values of the resistance values of the 25 thick film negative characteristic resistors was defined as the “measured resistance value”, which was used for the calculation of the following converted area resistance value.

The converted area resistance value is the value when the converted film thickness is 7 μm using the “measured film thickness” and “measured resistance value” calculated for each sample, according to the calculation formula shown in the following formula (1). Calculated.
Converted area resistance value (kΩ) = actual resistance value × (actual film thickness / converted film thickness) (1)

  For the variation in resistance value, a value obtained by dividing the standard deviation of the resistance values of the 25 thick film negative characteristic resistors by the average value was used.

The temperature coefficient of resistance (C-TCR, H-TCR) is determined by measuring the resistance value after holding the thick film negative characteristic resistor at −55 ° C., 25 ° C. and 125 ° C. for 15 minutes, respectively. _Was calculated from five thick film negative characteristic resistors, using values calculated by the following formulas (2) and (3) when R is R- ₅₅ , R ₂₅ , and R ₁₂₅ . The average value was used.
C-TCR (ppm / ° C.) = [(R ₋₅₅ −R ₂₅ ) / R ₂₅ ] / (− 80) × 10 ⁶ (2)
H-TCR (ppm / ° C.) = [(R ₁₂₅ −R ₂₅ ) / R ₂₅ ] / (100) × 10 ⁶ (3)

  Table 4 shows the converted area resistance value, variation in resistance value, and resistance temperature coefficient (C-TCR, H-TCR) value of each sample obtained by the above calculation method.

When only Example 1 and Example 2, Example 3 and Example 4, Example 5 and Example 6, Example 7 and Example 8 are compared, respectively, only the glass component is different, Example 2, Example 4, Example 6, and Example 8 using glass B, which has a temperature coefficient of resistance and in particular the content of B ₂ O ₃ in the glass is within the preferred range, It can be understood that the value of the temperature coefficient of resistance is more negative, indicating a more preferable thermistor characteristic as a negative characteristic thermistor.

  In contrast, Comparative Example 1 is an example using a ruthenium niobium-containing composite oxide powder in which the Nb content is 2:98 (Nb content ratio is 2 mol%) in the molar ratio of Nb: Ru. It is. In Comparative Example 1, the value of the resistance temperature coefficient in the negative direction becomes small, and it cannot be said that sufficient thermistor characteristics are obtained. Comparative Example 2 is an example using a ruthenium niobium-containing composite oxide powder in which the Nb content is 30:70 (the Nb content ratio is 30 mol%) in terms of the Nb: Ru molar ratio. . In Comparative Example 2, it is understood that since the variation in the resistance value of the thermistor is large, there arises a problem that the yield in manufacturing the thermistor is greatly reduced.

Claims (6)

Containing conductive particles and glass frit,
The conductive particles are composed of a ruthenium niobium-containing composite oxide powder represented by the general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0.50), and
The Pb content in the glass frit is less than 0.1% by mass.
Composition for negative characteristic resistor. The glass frit is made of Si—B—Al—Ba—Zn—O-based glass powder containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO, and B ₂ in the glass powder. The composition for negative characteristic resistors according to claim 1, wherein the content of O ₃ is in the range of 14% by mass to 25% by mass.   The composition for negative characteristic resistors according to claim 1 or 2, wherein a mass ratio of the ruthenium niobium-containing composite oxide powder and the glass frit is in a range of 25:75 to 65:35. An organic vehicle and a composition for negative characteristic resistor dispersed in the organic vehicle,
The composition for negative characteristic resistors is the composition for negative characteristic resistors according to any one of claims 1 to 3.
Resistance paste for negative characteristic resistors. A ceramic substrate;
A thick film negative characteristic resistor provided on the ceramic substrate;
Have
The thick film negative characteristic resistor includes a conductor component and a caking agent, and the composition of the conductor component is represented by a general formula: Bi ₂ Ru _2-x Nb _x O ₇ (0.06 ≦ x ≦ 0. 50), and the content of Pb in the caking agent is less than 0.1% by mass,
Negative characteristic thermistor. The caking agent is made of Si—B—Al—Ba—Zn—O-based glass containing SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, and ZnO, and B in the glass The negative characteristic thermistor according to claim 5, wherein the content of ₂ O ₃ is in the range of 14% by mass to 25% by mass.