Thick film resistor paste, thick film resistors, and electronic components

Abstract

To provide: a thick film resistor paste for resistors, which is excellent in surge resistance with a smaller resistance change rate for an electronic component that is reduced in size furthermore; a thick film resistor using the thick film resistor paste; and an electronic component including the thick film resistor.SOLUTION: Provided is a thick film resistor paste containing a conductive particle, glass powder, an organic vehicle, and an additive. The additive contains at least one of zinc oxide or silicon oxide, and the content of the zinc oxide and the content of the silicon oxide which are added as the additive each are 1 mass% or more and 19 mass% or less with respect to 100 mass% of the glass powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thick film resistor paste, and more particularly to a thick film resistor paste capable of forming a thick film resistor having excellent surge resistance, a thick film resistor using the thick film resistor paste, and an electronic component including the thick film resistor. [Background technology]

[0002] Thick-film resistor pastes generally consist of conductive powder, glass powder, and an organic vehicle for forming them into a paste suitable for printing. This thick-film resistor paste is printed in a desired pattern, and the glass is sintered at a high temperature, typically 800 to 1000°C, to produce thick-film resistors that constitute electronic components such as thick-film chip resistors. Ruthenium oxide powder and lead ruthenate powder are widely used as the conductive powder, as their resistance value can be gradually changed by adjusting the mixing ratio with the glass powder.

[0003] For example, Patent Document 1 describes a technology for a thick-film resistor formed using a resistor paste obtained by adding a vehicle using ethyl cellulose as a binder and toluene and alcohol as a solvent to a mixture of mullite as inorganic particles, lead borosilicate glass as glass particles, and ruthenium dioxide as conductive particles.

[0004] Furthermore, Patent Document 2 describes a resistor paste obtained by adding a vehicle using ethyl cellulose as a binder and terpineol and butyl carbitol acetate as a solvent to a mixture using zircon as inorganic particles, borosilicate lead glass as glass particles, and ruthenium dioxide as conductive particles, and also describes a technology for a thick-film resistor formed using the resistor paste.

[0005] In recent years, the miniaturization of electronic components such as thick-film chip resistors has led to demand for improved electrical properties in thick-film resistors, particularly those with excellent voltage resistance, such as surge resistance. When a momentary high voltage (surge voltage) is applied to a thick-film resistor, it typically exhibits a negative resistance change. However, a small change in resistance is desirable. This negative resistance change is thought to be the result of heat generated when voltage is applied. In conventional thick-film resistor pastes, the glass powder particles bond together during sintering, but softening of the glass powder is limited to the surface layer. As a result, a dielectric layer equivalent to the diameter of the glass particles exists in the thick-film resistor after sintering the thick-film resistor paste. Conductive powder is distributed around this dielectric layer, providing electrical conductivity to the thick-film resistor. When a surge voltage is applied to such a structure, current flows through the conductive portion, locally heating the surrounding area and causing a change in resistance.

[0006] One method for improving the surge resistance of thick-film resistors is to increase the amount of lead ruthenate contained in the thick-film resistor paste. By increasing the amount of lead ruthenate contained in the thick-film resistor paste, a thick, strong conductive part with a thick conductive path is formed in the thick-film resistor after sintering the thick-film resistor paste, which is thought to suppress heat generation when a surge voltage is applied and mitigate changes in resistance value. However, an increase in the amount of lead ruthenate as conductive powder results in a change in resistance value. For this reason, a technique is known in which additives such as titanium compounds are added as disclosed in Patent Document 3 to improve electrical characteristics including voltage resistance characteristics.

[0007] As another method for improving the surge resistance of thick-film resistors, for example, Patent Document 4 discloses a technology for a thick-film resistor composition that uses plate-shaped ruthenium oxide powder to minimize change in resistance value even when a surge current is applied. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 4-320003 [Patent Document 2] Japanese Patent Application Publication No. 6-163202 [Patent Document 3] Japanese Patent Application Laid-Open No. 1986-206201 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-053030 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in recent years, thick-film resistors for electronic components have become increasingly smaller, and conventional additives have not been able to sufficiently improve their characteristics, requiring higher surge resistance. Furthermore, as miniaturization continues, thick-film resistors are also required to be thinner, but plate-shaped materials have poor fluidity when applied. The present invention has been made in view of such problems, and aims to provide a thick film resistor paste for resistors with a smaller rate of resistance change and excellent surge resistance for electronic components that are becoming increasingly smaller, a thick film resistor using this thick film resistor paste, and an electronic component equipped with this thick film resistor. [Means for solving the problem]

[0010] As a result of various studies, the inventors of the present invention found that thick film resistors formed from thick film resistor pastes to which zinc oxide or silicon oxide is added separately from the constituent elements of glass powder have superior surge resistance compared to thick film resistors formed from conventional thick film resistor pastes, leading to the development of the present invention.

[0011] That is, the thick film resistor paste according to the present invention has the following properties: Composed of ruthenium oxide and lead ruthenate A thick film resistor paste containing conductive particles, glass powder, an organic vehicle, and an additive, wherein the additive is zinc oxide. and silicon oxide The base The content of the zinc oxide and the content of the silicon oxide added as the additive are, relative to 100% by mass of the glass powder, 9.6 Mass% or more 18.8It is characterized in that the proportion is % by mass or less.

[0012] In the thick film resistor paste of the present invention, the zinc oxide and silicon oxide preferably each have an average particle size of 100 nm or less, and the conductive particles preferably comprise one or more of ruthenium oxide and lead ruthenate.

[0013] The thick film resistor according to the present invention is characterized by comprising a fired body of any of the above thick film resistor pastes according to the present invention.

[0014] An electronic component according to the present invention is characterized by comprising the above-described thick film resistor according to the present invention. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a thick film resistor paste having better surge resistance than conventional thick film resistor pastes, a thick film resistor using the thick film resistor paste, and an electronic component including the thick film resistor. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments within the scope of the present invention. The thick film resistor paste of this embodiment contains conductive particles, glass powder, an organic vehicle, and additives. Each component will be described in detail below.

[0017] (Conductive particles) The conductive particles in the thick film resistor paste of the present invention are ,acid Ruthenium chloride or ruthenic acid Lead Use do. Ruthenic acid Lead The particle size is not particularly limited, but the specific surface area is preferably 5m 2 It is desirable to have a particle size of 5m / g or more. 2If the particle size is less than 1 / g, the particle size of lead ruthenate is too large, which may reduce the uniformity of the conductive region in the thick film resistor and deteriorate the surge resistance. Ruthenium oxide Mu's The particle size is not particularly limited, but a specific surface area of ​​20 m 2 It is desirable to have a particle size of 20m / g or more. 2 If the ruthenium oxide content is less than 1 / g, the particle size of the ruthenium oxide will be too large, which may reduce the uniformity within the thick film resistor and deteriorate the surge resistance.

[0018] (glass component) The glass component in the thick-film resistor paste of the present invention is not particularly limited, and glass components conventionally used in thick-film resistor pastes can be used. For example, glass commonly referred to as lead borosilicate glass, which contains silicon oxide (SiO), lead oxide (PbO), and boron oxide (BO), can be used. Other glass components may also include magnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), strontium oxide (SrO), cadmium oxide (CdO), tin oxide (SnO), zinc oxide (ZnO), and bismuth oxide (BiO). Aluminum oxide (AlO) may also be included.

[0019] (Silicon oxide: SiO2) SiO2 is a component that is often used as the skeleton of glass components. SiO2 is preferably contained in an amount of 3% by mass or more and 60% by mass or less based on 100% by mass of the glass component. If the amount is more than 60% by mass, the softening point of the glass formed will be too high. If the amount is less than 3% by mass, chemically stable glass will not be obtained.

[0020] (Lead oxide: PbO) PbO is a component that lowers the softening point, promotes wetting with ruthenium oxide, improves dispersibility, and chemically stabilizes lead ruthenate and inhibits decomposition. PbO is preferably contained in an amount of 30% by mass to 90% by mass based on 100% by mass of the glass components. If it is less than 30% by mass, the softening point of the resulting glass will be too high. If it is more than 90% by mass, it will be difficult to obtain a chemically stable glass state.

[0021] (boron oxide: B2O3) B2O3, together with SiO2, is a component often used as the framework of glass components, and has the effect of lowering the softening point of the glass that is formed. B2O3 is preferably contained in an amount of 5% by mass or more and 50% by mass or less, based on 100% by mass of the glass component. If it is less than 5% by mass, the toughness of the formed glass decreases, cracks tend to occur, and laser trimming properties deteriorate. Furthermore, if it is more than 50% by mass, phase separation of the glass component tends to occur, and water resistance also decreases.

[0022] (Total content of major glass components) The total content of SiO2, PbO, and B2O3 in 100% by mass of the glass component is preferably 50% by mass or more. If the content is less than 50% by mass, it becomes difficult to stably form the glass, and it becomes difficult to obtain satisfactory surge resistance as an electrical characteristic of the thick-film resistor.

[0023] (Other glass components) In addition to the above main glass components, other oxides may be further contained as glass components to improve various properties. Specifically, Al2O3, MgO, CaO, BaO, SrO, CdO, SnO, ZnO, Bi2O3, etc. may be contained. These glass components are preferably contained in an amount of 20 mass% or less each based on 100 mass% of the glass components.

[0024] (organic vehicle) There are no particular restrictions on the organic vehicle used in the thick-film resistor paste of the present invention, and it is possible to use a solvent such as terpineol, which is used in general resistor pastes, in which a resin such as ethyl cellulose or rosin is dissolved. The amount of the organic vehicle to be blended may be adjusted appropriately depending on the printing method, etc., but it is generally preferable that the organic vehicle be contained in an amount of 20% by mass or more and 50% by mass or less relative to 100% by mass of the total amount of the resistor paste.

[0025] (additives) The additive in the thick film resistor paste of the present invention is zinc oxide. and silicon oxide The base Zinc oxide and silicon oxide are also part of the materials that make up the glass component, but the inventors have discovered that zinc oxide is contained in addition to the components that form the glass. and silicon oxide The base It has been discovered that by adding a predetermined amount of a single oxide as an additive to a thick film resistor paste, the resistance decrease rate of the thick film resistor formed from the thick film resistor paste can be more efficiently suppressed and the surge resistance can be improved. The content of zinc oxide and the content of silicon oxide added as additives are each 1% by mass or more and 19% by mass or less, based on 100% by mass of the glass powder. 1 If the content is less than 19% by mass, the rate of decrease in resistance cannot be sufficiently suppressed, and if the content exceeds 19% by mass, not only is it not possible to suppress the rate of decrease in resistance, but the increase in resistance becomes more pronounced. The particle sizes of zinc oxide and silicon oxide are not particularly limited and may be selected according to the shape and size of the electronic components to be used. However, for the same content, the smaller the particle size, the greater the effect of suppressing the rate of resistance decline. In addition, as electronic components become smaller, thinner resistor films are required. Therefore, it is preferable to set the average particle size to 100 nm or less. The average particle sizes of zinc oxide and silicon oxide are values ​​obtained by the BET method.

[0026] (Other additives) The thick-film resistor paste of the present invention may further contain conductive-free lead borosilicate glass, which has traditionally been used to improve the resistance, TCR, and voltage resistance of thick-film resistors, as well as commonly used additives. A dispersant may also be added to improve dispersion. Typical additives include niobium oxide (NbO), tantalum oxide (TaO), titanium oxide (TiO), copper oxide (CuO), manganese oxide (MnO), zirconium oxide (ZrO), and aluminum oxide (AlO). The content of these additives can be adjusted depending on the desired characteristics, but it is preferable to include no more than 10% by mass of the total inorganic materials (100% by mass).

[0027] (Method of manufacturing thick film resistor paste) Conductive particles, glass powder, organic vehicle, and additives were mixed in various proportions to prepare several resistive paste samples, which were then fired to form thick-film resistors, and their electrical properties were evaluated.

[0028] (Manufacturing method of thick film resistors) The resulting thick film resistor paste is printed on a ceramic substrate, the organic solvent is removed by drying, and then the substrate is fired at a temperature of, for example, 800° C. to 900° C. to obtain a thick film resistor. [Example]

[0029] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. It is not something that can be determined. It should be noted that Examples 1 to 10 and 14 described below are reference examples.

[0030] [Test 1] (Comparative Example 1) A comparative sample, a resistive paste of Comparative Example 1, which corresponds to a conventional resistive paste, was prepared. Ruthenium oxide and lead ruthenate were used as conductive particles. Lead borosilicate glass was used as glass powder. Niobium oxide and copper oxide were used as other additives, and an organic vehicle mainly composed of ethyl cellulose and terpineol was used. The conductive particles, glass powder, other additives, and organic vehicle were weighed out in the blending ratios shown in Table 1 and kneaded in a three-roll mill to prepare a resistive paste of Comparative Example 1.

[0031] (Examples 1 to 5, Comparative Example 2) In addition to the materials used to prepare the resistive paste of Comparative Example 1, zinc oxide having a particle size of 20 nm was further prepared as an additive, and copper oxide was also prepared in addition to niobium oxide as other additives. These materials were kneaded in the blending ratios shown in Table 1 in the same manner as in Comparative Example 1 to prepare the resistive pastes of Examples 1 to 5 and Comparative Example 2.

[0032] (Examples 6 to 10, Comparative Example 3) In addition to the materials used to prepare the resistive paste of Comparative Example 1, silicon oxide with a particle size of 28 nm was further prepared as an additive, and copper oxide was also prepared in addition to niobium oxide as another additive. These materials were kneaded in the blending ratios shown in Table 1 in the same manner as in Comparative Example 1 to prepare the resistive pastes of Examples 6 to 10 and Comparative Example 3.

[0033] Examples 11 to 13 In addition to the materials used to prepare the resistive paste of Comparative Example 1, both zinc oxide with a particle diameter of 20 nm and silicon oxide with a particle diameter of 28 nm were prepared as additives, and copper oxide was also prepared in addition to niobium oxide as other additives. These materials were kneaded in the blending ratios shown in Table 1 in the same manner as in Comparative Example 1 to prepare the resistive pastes of Examples 11 to 13.

[0034] Comparative Example 4 As a comparative sample for Examples 3 and 8, aluminum oxide having a particle size of 15 nm, which can be used as another additive, was prepared in place of zinc oxide, which is an essential additive in the present invention. These materials were kneaded in the proportions shown in Table 1 in the same manner as in Example 3 to prepare a resistive paste for Comparative Example 4.

[0035] <Evaluation test> (Preparation of evaluation samples) Using each of the resistor pastes of Examples 1 to 13 and Comparative Examples 1 to 4, the thick-film resistor paste was printed with a width of 1.0 mm on an alumina substrate on which electrodes (five pairs of electrodes spaced 1.0 mm apart) had been formed in advance using Ag / Pd paste, and the paste was dried in a belt furnace at a peak temperature of 150°C for 5 minutes. Then, the paste was fired in a belt furnace at a peak temperature of 850°C for 9 minutes to produce five thick-film resistors as evaluation samples. Five similar evaluation samples were produced per alumina substrate, yielding 25 thick-film resistors as evaluation samples.

[0036] (film thickness measurement) The film thickness was measured by using a stylus-type surface roughness meter to randomly select one alumina substrate from the evaluation samples, measure the film thickness of each of the five thick-film resistors, and record the average value of the five points as the measured film thickness.

[0037] (converted area resistance value) The resistance values ​​at 25°C of five evaluation samples (25 samples in total) formed on five alumina substrates were measured using a circuit meter (2001 MULTIMETER, manufactured by KEITHLEY), and the average value was used as the actual measured resistance value. The converted sheet resistance when the film thickness was 7 μm was calculated using the following formula (1). The calculated converted sheet resistance values ​​are shown in Table 1. Converted sheet resistance (kΩ) = measured resistance (kΩ) × (measured film thickness (μm) / 7 (μm) (1)

[0038] (Surge resistance evaluation: resistance change rate) An electrostatic discharge test was performed on the thick-film resistor used as the evaluation sample using a semiconductor device electrostatic tester (ESS-6008, manufactured by Noise Laboratory) by applying a voltage under the conditions of a capacitance of 200 pF and an internal resistance of 0 Ω. A voltage of 5 kV was applied to the thick-film resistor used as the evaluation sample five times at one-second intervals, and the resistance value Rs before and the resistance value Re after the voltage application were measured. The resistance change rate was calculated using the following formula (2). The average resistance change rate calculated at five points is shown in Table 1. Resistance change rate (%) = (Re-Rs) / Rs × 100 (2)

[0039] [Table 1] (*1): The content of zinc oxide, silicon oxide, and aluminum oxide added as additives (ratio (mass%) relative to 100% by mass of glass powder). However, in Examples 11 to 13, the content of zinc oxide and the content of silicon oxide added as additives (ratio (mass%) relative to 100% by mass of glass powder are the same, so only one of the data is shown).

[0040] As shown in Table 1, the thick-film resistors formed with the thick-film resistor pastes of Examples 1 to 5, which were prepared using zinc oxide as an additive in addition to the components that form the glass, had a lower rate of change in resistance value before and after the electrostatic discharge test and were found to have better surge resistance than the thick-film resistor formed with the thick-film resistor paste of Comparative Example 1, which corresponds to a conventional thick-film resistor paste prepared without using zinc oxide as an additive. Also, the thick-film resistor formed with the thick-film paste of Comparative Example 2, in which the amount of zinc oxide added was greater than the range of the present invention, had a rate of change in resistance similar to that of the conventional thick-film resistor, and it was found that no improvement in surge resistance was achieved. Furthermore, it was also confirmed that the resistance change rates of the thick-film resistors formed using the thick-film resistor pastes of Examples 6 to 10, which were produced using silicon oxide as an additive in addition to the components that form the glass, had the same excellent surge resistance effect as the thick-film resistors formed using the thick-film resistor pastes of Examples 1 to 5. It was also confirmed that the thick-film resistor formed using the thick-film paste of Comparative Example 3, in which the amount of silicon oxide added was greater than the range of the present invention, had a resistance change rate similar to that of a conventional thick-film resistor, and did not achieve the effect of improving surge resistance. Furthermore, as shown by the results of the resistance change rate of the thick film resistors formed using the thick film resistor pastes of Examples 11 to 13, which were produced using zinc oxide and silicon oxide as additives separately from the components that form the glass, the resistance change rate of the thick film resistor formed using the thick film resistor paste of Example 13, which contains each additive at a ratio of 18.8 mass% relative to 100 mass% of the glass powder, for a total ratio of 37.6 mass%, exhibits a good effect.This shows that the contents of zinc oxide and silicon oxide added as additives of the present invention, when they each satisfy the ratio of 1 mass% to 19 mass% relative to 100 mass% of the glass powder, individually exhibit the effect of improving surge resistance. Furthermore, the thick film resistor formed using the thick film resistor paste of Comparative Example 4, in which aluminum oxide, a type of other additive conventionally used, was added in the same manner as the additive of the present invention, had a slightly lower resistance change rate than Comparative Example 1, but it was found that the surge resistance was not sufficiently improved compared to the thick film resistors formed using the thick film resistor pastes of Examples 3 and 8, in which zinc oxide or silicon oxide of the present invention was added.

[0041] [Test 2] Example 14 To confirm the effect of the particle size of the additive, a thick film resistor was formed using the thick film resistor paste of Example 14, which had a composition similar to that of Example 3, except that the average particle size of zinc oxide, an additive separate from the glass-forming component, was changed from 20 nm to 35 nm. The converted sheet resistance and resistance change rate of the formed thick film resistor were determined in the same manner as in Test 1, and surge resistance was confirmed. The obtained evaluation results are shown in Table 2, along with the results of Comparative Example 1 and Example 3.

[0042] [Table 2] (*2): The amount of zinc oxide added as an additive (percentage (mass%) relative to 100% glass powder).

[0043] As shown in Table 2, Example 14, which had a different particle size from Example 3, had a lower resistance change rate than Comparative Example 1 and was found to have the same excellent surge resistance as Example 3. The particle size of the additive affects the viscosity characteristics, so it can be selected appropriately depending on the conditions of use. However, given the trend toward smaller electronic components and the demand for thinner resistors, it is preferable that the particle size of the additive be 100 nm or less.

[0044] From the above test results, it is recognized that the thick film resistor formed using the thick film resistor paste of the present invention has excellent surge resistance and can be suitably used in electronic components that have become increasingly smaller in recent years.

Claims

1. A thick film resistor paste containing conductive particles consisting of ruthenium oxide and lead ruthenate, glass powder, an organic vehicle, and additives, the additive contains zinc oxide and silicon oxide; the content of the zinc oxide and the content of the silicon oxide added as the additive are each in a ratio of 9.6 mass% or more and 18.8 mass% or less with respect to 100 mass% of the glass powder; A thick film resistor paste characterized by:

2. 2. The thick film resistor paste according to claim 1, wherein the zinc oxide and silicon oxide each have an average particle size of 100 nm or less.

3. A thick film resistor comprising a fired body of the thick film resistor paste according to claim 1 or 2.

4. An electronic component comprising the thick film resistor according to claim 3.

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