WO2009119154A1 - Base metal powder, process for producing the base metal powder, conductor paste, and electronic component - Google Patents

Base metal powder, process for producing the base metal powder, conductor paste, and electronic component Download PDF

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Publication number
WO2009119154A1
WO2009119154A1 PCT/JP2009/051356 JP2009051356W WO2009119154A1 WO 2009119154 A1 WO2009119154 A1 WO 2009119154A1 JP 2009051356 W JP2009051356 W JP 2009051356W WO 2009119154 A1 WO2009119154 A1 WO 2009119154A1
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Prior art keywords
base metal
metal powder
main peak
insulator
conductor
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PCT/JP2009/051356
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French (fr)
Japanese (ja)
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寺師　吉健
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京セラ株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0545—Dispersions or suspensions of nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
    • H01B1/026—Alloys based on copper
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/005—Electrodes
    • H01G4/008—Selection of materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/005—Electrodes
    • H01G4/008—Selection of materials
    • H01G4/0085—Fried electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics

Definitions

  • the present invention relates to a fine base metal powder and a manufacturing method thereof, a conductor paste using the base metal powder, and an electronic component including a conductor film formed using the conductor paste.
  • Patent Document 1 nickel hydroxide is used as a starting material, an alkaline earth metal oxide is mixed with the starting material, and heated to a temperature of 800 ° C. or higher in a hydrogen reducing atmosphere, whereby the maximum of one particle is obtained.
  • a production method for obtaining a flat nickel powder having a projected diameter of 500 to 3000 nm and a thickness of 50 to 900 nm is described.
  • Patent Document 2 nickel chloride is used as a starting material, titanium isopropoxide, barium hydroxide and sodium hydroxide are added thereto, and these are dissolved in ion-exchanged water at 60 ° C. for 1 hour. A process for obtaining a base metal powder mainly composed of nickel having a particle diameter of 100 nm is described.
  • Patent Document 3 as a starting material, a noble metal such as palladium is added to nickel hydroxide, and this is put into an ethylene glycol solution and heated to reduce, so that the average particle diameter is 20 to 100 nm. A process for obtaining nickel powder with small particle size variation is described.
  • the base metal powder of the present invention has a base metal as a main component and an average particle size of 5 to 30 nm.
  • the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the base metal oxide main peak is a cubic close-packed structure of the base metal (ccp). Is 10% or less of the diffraction intensity of the main peak.
  • the method for producing a base metal powder of the present invention includes the following steps (a) to (c).
  • (A) A step of preparing a base metal-containing solution by dissolving a nitrate of base metal and sodium oleate or sodium maleate in a mixed solvent of water and two kinds of solvents having a polarity lower than that of water.
  • (B) A step of obtaining a precursor of oleic acid or maleic acid containing the base metal from the base metal-containing solution.
  • C A step of heating the oleic acid precursor or maleic acid precursor containing the base metal at a temperature of 250 to 400 ° C. in a reducing atmosphere.
  • the conductor paste of the present invention contains the base metal powder and an organic vehicle.
  • the electronic component of the present invention includes an insulator and a conductor film provided on the surface of the insulator. And the said conductor film is formed by baking the said conductor paste provided in the surface of the said insulator.
  • the base metal powder and the conductor paste of the present invention an extremely thin conductor film can be formed. For this reason, it is possible to suppress the occurrence of delamination or the like in an electronic component in which an insulator and a conductor film are laminated in multiple layers. Moreover, according to the manufacturing method of the base metal powder of the present invention, it is possible to easily mass-produce ultrafine and high-purity base metal powder capable of forming an extremely thin conductor film. According to the electronic component of the present invention, it is possible to further reduce the size and thickness.
  • nickel powder which is an example of the base metal powder of the present invention. It is an X-ray-diffraction pattern of the nickel powder which is an example of the base metal powder of this invention. It is a schematic diagram which shows the state which the precursor of the oleic acid or maleic acid to produce
  • the base metal powder of this embodiment is mainly composed of base metals such as nickel, copper and cobalt.
  • the base metal component is preferably nickel or copper. Since nickel or copper is less expensive than noble metals such as gold, silver, palladium, and platinum, there is an advantage that the manufacturing cost can be reduced when applied to a conductor film constituting a multilayer electronic component.
  • the base metal powder of this embodiment has an average particle size of 5 to 30 nm (see FIG. 1).
  • the average particle size of the base metal powder is 5 nm or more, the crystallinity is high and the base metal powder has high purity, non-uniform reaction is suppressed, and aggregation during heating can be suppressed.
  • the average particle size is 30 nm or less, a very thin conductor film can be formed on the surface of an insulator such as a dielectric layer, so that a step due to the conductor film can be reduced. Therefore, it is possible to suppress the occurrence of delamination or the like in an electronic component in which an insulator and a conductor film are laminated in multiple layers.
  • the average particle diameter of the base metal powder is preferably 7 to 10 nm.
  • the reactivity of the base metal powder can be further stabilized, so that aggregation is suppressed and thinning is possible.
  • the average particle diameter of the base metal powder is smaller than 5 nm, the crystallinity is lowered and the ratio of the cubic close-packed structure (ccp) is lowered. Furthermore, since the shape of the base metal powder is likely to be uneven, a non-uniform reaction is likely to occur. For this reason, it becomes easy to aggregate, and as a result, it becomes difficult to make a conductor film thin.
  • the average particle size of the base metal powder is larger than 30 nm, it is difficult to form a thin conductor film on the surface of an insulator such as a dielectric layer. For this reason, in an electronic component in which an insulator and a conductor film are laminated in multiple layers, a step due to the thickness of the conductor film is increased, and defects such as delamination are likely to occur.
  • the average particle diameter is a value measured using a scanning electron microscope, as will be described later. Moreover, the said average particle diameter can be controlled to a desired value in the manufacturing method of this embodiment mentioned later by adjusting the heating temperature in the reducing atmosphere in (c) process, for example.
  • the base metal powder of the present embodiment has a diffraction intensity of the stronger one of the main peak of the base metal hexagonal close-packed structure (hcp) and the main peak of the base metal oxide in the base metal cubic. It is 10% or less of the diffraction intensity of the main peak of the closest packed structure (ccp).
  • FIG. 2 is an X-ray diffraction pattern of nickel powder which is an example of the base metal powder of this embodiment.
  • FIG. 2 is an X-ray diffraction pattern of nickel powder which is an example of the base metal powder of this embodiment.
  • the heating temperature of No. 3 is 250 ° C.
  • FIG. This is a case where the heating temperature of 6 is 400 ° C.
  • the base metal powder of the present embodiment has a base metal (nickel: Ni) hexagonal close-packed structure (hcp) main peak (111) and base metal oxide (nickel oxide: nickel oxide) in an X-ray diffraction pattern.
  • the stronger diffraction intensity of the main peak (200) of NiO) is 10% or less of the diffraction intensity of the main peak (111) of the base metal cubic close-packed structure (ccp).
  • the base metal powder of this embodiment has the average particle size as described above, since the ratio of the cubic close-packed structure having a high close-packed structure as a metal is large, a metal slip surface is likely to appear. Therefore, it is possible to obtain a highly conductive material having high malleability and ductility.
  • the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the main peak of the base metal oxide is 5% of the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp).
  • the content of the base metal in the base metal powder is preferably 99% or more.
  • the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the base peak of the base metal oxide is the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp).
  • it is higher than 10% it becomes difficult to obtain malleability, ductility and high electrical conductivity.
  • the diffraction intensity in the X-ray diffraction pattern is a value measured using an X-ray diffractometer, as will be described later.
  • the diffraction intensity of the stronger one of the main peak of the base metal hexagonal close-packed structure (hcp) and the base peak of the base metal oxide is 10% of the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp).
  • the heating temperature in the reducing atmosphere in the step (c) can be adjusted to a desired value.
  • the method for producing a base metal powder of the present embodiment includes the following steps (a) to (c).
  • step (a) base metal nitrate and sodium oleate or sodium maleate are placed in a glass container 10 shown in FIG. Further, water and two kinds of solvents having a polarity lower than that of water are added to prepare a base metal-containing solution in which base metal components are dissolved in these three kinds of mixed solvents.
  • nickel nitrate, copper nitrate or cobalt nitrate is preferably used, and nickel nitrate or copper nitrate is more preferably used.
  • nickel nitrate or copper nitrate is more preferably used.
  • These nitrates may be hydrates, but the purity of the nitrate used is preferably 99% or more because high-purity base metal powder can be obtained.
  • water and a polar than the water are used as a solvent for dissolving the nitrate containing the base metal and forming a precursor containing the base metal after the reaction is completed. And two low solvents.
  • water is described as a first solvent, and two kinds of solvents having a polarity lower than that of water are described as second and third solvents.
  • the first solvent water (polarity: 21), is preferably ion-exchanged water.
  • the second solvent which is a solvent having a polarity lower than that of water, one solvent selected from butyl alcohol (polarity: 10.7), hexane (polarity: 7.3) and octane (polarity: 7.0) Is preferably used.
  • the polarity of the solvent is an amount representing a state in which the distribution of the electron cloud is biased due to the difference in electronegativity of the component atoms, and the dipole is formed without the center of gravity of the positive and negative charges being matched. This is a value represented by the square root of the value obtained by dividing the molar evaporation energy by the volume per mole.
  • a solvent having an intermediate polarity between water and the second solvent is preferably selected.
  • 1 selected from methyl alcohol, ethyl alcohol, and propyl alcohol. It is preferred to use a seed solvent.
  • three types of solvents having different polarities are used for the following reason. That is, the use of highly polar water as the first solvent facilitates the dissolution of nitrates containing base metals, and also dissolves the sodium component contained in sodium oleate or sodium maleate described below in water. Because you can.
  • one solvent selected from butyl alcohol, hexane, and octane, which is less polar than water, as the second solvent facilitates dissolution of the above-mentioned sodium oleate or sodium maleate, and also provides sodium oleate or maleic acid. This is because an oleic acid precursor or a maleic acid precursor containing a base metal formed with sodium as a nucleus is easily formed.
  • the third solvent having a polarity intermediate between water and the second solvent uses water as the first solvent and methyl alcohol (polarity: 12.9) as the second solvent, ethyl alcohol. (Polarity: 11.2) and one solvent selected from propyl alcohol (polarity: 11.5) are mixed uniformly without separation. This makes it possible to uniformly mix base metal nitrate that is easily dissolved in water and sodium oleate or sodium maleate that is easily dissolved in the second solvent.
  • the base metal-containing solution is gently left to obtain an oleic acid precursor 20 or a maleic acid precursor 20 containing a base metal, as shown in FIG.
  • the base metal-containing solution is separated between the water 21 and one solvent selected from butyl alcohol, hexane, and octane.
  • a maleic acid precursor 20 is formed in the second solvent.
  • the precursor 20 of oleic acid and the precursor 20 of maleic acid are polymers.
  • the reason why the base metal-containing solution is allowed to stand gently is to increase the yield of the oleic acid precursor 20 or maleic acid precursor 20 containing the base metal, and to increase the decomposability of these precursors 20 by heating. Therefore, 1 to 48 hours at a temperature of 10 to 50 ° C. is preferable.
  • the lower layer solution separated by opening the discharge port 11 of the glass container 10 is discharged, and only the second solvent containing the oleic acid precursor 20 containing the base metal or the maleic acid precursor 20 is extracted. . Thereafter, the solvent is dried from the solution containing the base metal-containing oleic acid precursor 20 or the maleic acid precursor 20 to obtain the base metal-containing oleic acid precursor 20 or the maleic acid precursor 20.
  • the obtained oleic acid precursor 20 or maleic acid precursor 20 containing the base metal is heated at a temperature of 250 to 400 ° C. in a reducing atmosphere (N 2 /5% H 2 ). Heat with.
  • the base metal powder of this embodiment with ultrafine particles and high purity is obtained.
  • the base metal powder manufacturing method of the present embodiment including the steps (a) to (c) is suitable for mass production.
  • the heating temperature is preferably 270 to 370 ° C., more preferably 300 to 350 ° C. in that the ratio of the cubic close-packed structure (ccp) is high and the average particle size can be 7 to 10 nm. preferable.
  • the heating temperature is lower than 250 ° C.
  • the decomposition reaction of the precursor 20 of oleic acid or the precursor 20 of maleic acid is not accelerated and the precursor 20 tends to remain.
  • the heating temperature is higher than 400 ° C.
  • the decomposition reaction of the precursor 20 of oleic acid or the precursor 20 of maleic acid proceeds and the amount of the remaining precursor 20 is reduced, but the obtained base metal powder is granulated. Since it grows, it becomes difficult to obtain ultrafine base metal powder.
  • the conductor paste of this embodiment contains the base metal powder and the organic vehicle.
  • the organic vehicle include cellulosic polymers such as ethyl cellulose, organic solvents such as ethylene glycol and diethylene glycol derivatives, toluene, xylene, mineral spirits, butyl carbitol, and ⁇ -terpineol (terpineol). Alternatively, two or more kinds may be mixed and used.
  • the conductive paste may contain various inorganic additives as subcomponents as necessary as long as the original conductivity (low resistivity), solder heat resistance, adhesive strength, etc. of the conductive paste are not significantly impaired. be able to.
  • the inorganic additive include glass powder, inorganic oxide, and various other fillers.
  • the inorganic additive preferably has an average particle diameter equal to or less than that of the base metal powder.
  • the conductive paste may be prepared by, for example, directly mixing the base metal powder and various additives together with the organic vehicle at a predetermined mixing ratio using a three-roll mill or other kneader, and kneading them together.
  • the content of the base metal powder in the conductor paste is not particularly limited, but each material is preferably kneaded so that the content of the base metal powder as the main component is 60 to 95% by mass of the entire paste. .
  • the amount of the organic vehicle used for the preparation of the conductor paste is suitably about 1 to 40% by mass, particularly preferably 1 to 20% by mass of the entire paste. Moreover, when adding glass powder and ceramic powder as an inorganic additive, it is preferable to add in the ratio of 5 mass parts or less with respect to 100 mass parts of base metal powder.
  • the electronic component of this embodiment will be described by taking the multilayer ceramic capacitor shown in FIG. 4 as an example.
  • the following multilayer ceramic capacitor can be formed using the conductor paste of the present embodiment.
  • the multilayer ceramic capacitor in the present embodiment is provided with external electrodes 2 at both ends of the capacitor body 1.
  • the capacitor body 1 is configured by alternately laminating dielectric layers 3 that are insulators and internal electrode layers 4 that are conductor films.
  • the internal electrode layer 4 is formed of the above-described conductor paste of the present embodiment, and the thickness thereof is 100 nm or less, particularly 50 nm or less when the thickness of the dielectric layer 3 is 1 ⁇ m or less. desirable. Thereby, the electronic component obtained using the base metal powder of this embodiment can be made thin, the level
  • the above-described conductor paste is printed on a ceramic green sheet that becomes an insulator after firing, and a conductor pattern that becomes a conductor film after firing is formed.
  • the thickness of the conductor pattern after drying is preferably 100 nm or less, particularly preferably 50 nm or less.
  • a plurality of ceramic green sheets on which the above-described conductor pattern is formed are stacked, and are heated and integrated to form a base laminate.
  • the obtained base laminate is cut into a predetermined size to obtain an unsintered laminate that becomes the capacitor body 1 after firing.
  • this unfired laminate is degreased in the air or in a nitrogen atmosphere, and then fired in a reducing atmosphere of a hydrogen-nitrogen mixed gas at a temperature of 1000 to 1300 ° C. for 1 to 5 hours.
  • the oxidation treatment may be performed by reheating at a temperature lower than the firing temperature (900 to 1100 ° C.).
  • the capacitor body 1 in which the dielectric layers 3 as insulators and the internal electrode layers 4 as conductor films are alternately laminated and integrated is obtained.
  • an external electrode paste is applied to the opposite end portions of the capacitor body 1 and baked to form the external electrodes 2.
  • a plated film for improving the mountability is formed on the surface of the external electrode 2 to obtain a multilayer ceramic capacitor.
  • Ni (NO 3 ) 2 nickel nitrate (Ni (NO 3 ) 2 ), copper nitrate (Cu (NO 3 ) 2 ), and cobalt nitrate (Co (NO 3 ) 2 ) were prepared as metal sources.
  • this metal source and various solvents and additives shown in Table 1 were put into a glass container and mixed at room temperature (25 ° C.) to prepare a base metal-containing solution.
  • the mixing ratio is 10 parts by mass of the additive with respect to 100 parts by mass of the nitrate as the metal source, and 200 parts by mass of ion-exchanged water as the first solvent.
  • the addition amounts of the solvent and the third solvent were 300 parts by mass, respectively.
  • the base metal-containing solution was then separated into two upper and lower layers at 35 ° C. for 5 hours to form an oleic acid precursor or maleic acid precursor in the upper solution.
  • the lower side of the glass container was opened to discharge the solvent on the lower side of the container.
  • the solvent was discharged from the solution containing the oleic acid precursor or the maleic acid precursor by decantation to obtain an oleic acid precursor or a maleic acid precursor.
  • the obtained precursor of oleic acid or maleic acid was placed in a quartz vessel, placed in a heating furnace, and a mixed gas of N 2 -5% H 2 was supplied.
  • the precursor was decomposed by heating to the indicated temperature to obtain base metal powder (Sample Nos. 1 to 20 in Table 1).
  • the average particle diameter of the obtained base metal powder was calculated
  • ⁇ Evaluation> Average particle size
  • a photograph of the internal structure was taken using a scanning electron microscope (magnification: 200,000 times), and a circle containing 30 crystal particles was drawn on the photograph.
  • select the crystal particles in and around the circle image processing the contour of each crystal particle, calculate the equivalent circle diameter by assuming each particle as a circle, the average particle diameter from the average value Asked.
  • a conductor paste was prepared using the above-described base metal powder, and a multilayer ceramic capacitor was produced using this conductor paste as an internal electrode paste.
  • the base metal powder is 40% by mass
  • the organic vehicle ethylcellulose: 5.5% by mass, ⁇ -terpineol 94.5% by weight
  • an appropriate amount of solvent ⁇ - Terpineol
  • insulators to be applied to nickel powder, copper powder and cobalt powder were prepared.
  • the insulator is added to 100 mol parts of the main components (BaTiO 3 : 97.5 mol%, CaZrO 3 : 2.0 mol%, MnO: 0.5 mol%). in contrast, using the composition in which the Y 2 O 3 was added 0.5 parts by mole.
  • borosilicate glass powder with respect to the composition 100 parts by weight (SiO 2: 50 mol%, Al 2 O 3: 5 mol%, MgO: 30 mol%, B 2 O 3: 10 mol% , CaO: 5 mol%) was added at a ratio of 60 parts by mass to prepare ceramic slurry.
  • these ceramics were formed on a belt-like carrier film made of a synthetic resin of polyester by a die coater method and dried to obtain a ceramic green sheet having a thickness of 0.6 ⁇ m.
  • the above-mentioned conductor paste is applied to one main surface of the obtained ceramic green sheet using a gravure printing device.
  • a conductor pattern was formed by printing so that the printed thickness was 20 to 150 nm.
  • the thickness of the conductor pattern after printing was set to a thickness of 10 times or less the average particle diameter of the used base metal powder.
  • this unfired laminate was degreased in the temperature range up to 400 ° C. and fired in a reducing atmosphere.
  • the conductor film is formed at 1250 ° C. when formed with a conductor paste containing nickel powder, at about 1200 ° C. when formed with a conductor paste containing cobalt powder, and 920 when formed with a conductor paste containing copper powder.
  • the capacitor body was obtained by firing at 2 ° C. for 2 hours.
  • the external dimensions of the capacitor body thus obtained are 3.2 mm in length, 1.6 mm in width, and 1.0 mm in thickness, and the thickness of the dielectric layer interposed between the internal electrode layers is 0.4 ⁇ m. It was.
  • the effective area of the counter internal electrode layer per layer of the dielectric layer was 2.1 mm 2 .
  • the capacitor body obtained as described above was solidified with 100 samples of each sample and polished, and observed with a metal microscope at a magnification of 400 times to inspect for delamination. Table 1 shows the results.
  • the base metal powders (samples Nos. 3 to 6, 8 to 12, 15 to 18 and 20) obtained by the production method of the present invention have an average particle size of 5 to 30 nm.
  • the diffraction intensity of the stronger one of the main peak (111) of the hexagonal close-packed structure (hcp) and the main peak (200) of the base metal oxide with respect to the diffraction intensity of the main peak (111) of the cubic close-packed structure (ccp) It was 10% or less.
  • the sample No. which is the base metal powder of the present invention. 3 and 6 are found to be highly pure. Similarly to this, it was confirmed that the other base metal powder according to the present invention was of high purity from the result of the X-ray diffraction pattern.
  • a 360-layer laminate can be used without forming a step-resolving ceramic pattern around the internal electrode layer.
  • the number of laminations was 1 or less out of 100.
  • Nos. 4, 5, 8 to 12, 16, 17, and 20 have an average particle diameter of the base metal powder of 10 nm or less, and a hexagonal close-packed structure (hcp) with respect to the diffraction intensity of the main peak (111) of the cubic close-packed structure (ccp).
  • the diffraction intensity of the stronger one of the main peak (111) and the main peak (200) of the base metal oxide is 7% or less, and no delamination occurred in the 360-layer laminate. .
  • sample No. 1 was obtained by heating a precursor of oleic acid at 200 ° C. 1 and 13 had precursors remaining.
  • Sample No. obtained by heating the precursor at 230 ° C. 2 and 14 the stronger peak intensity of the (111) peak of the hexagonal close-packed structure (hcp) or the (200) peak of the base metal oxide was 17% or more.
  • Sample No. with heating temperature higher than 400 ° C was used. In Nos. 7 and 19, the average particle size of the base metal powder far exceeded 30 nm, and the evaluated capacitor body had a delamination generation rate of 10 out of 100.

Abstract

Disclosed is a base metal powder that is composed mainly of a base metal, has an average particle diameter of 5 to 30 nm, and exhibits such an X-ray diffraction pattern that the diffracted intensity of one of a main peak in a hexagonal closest packing structure (hcp) of the base metal and a main peak of an oxide of the base metal, which is a higher diffracted intensity, is not more than 10% of the diffracted intensity of a main peak in a cubic closest packing structure (ccp) of the base metal. Also disclosed are a process for producing the base metal powder, a conductor paste, and an electronic component. The conductor paste comprises the base metal powder and an organic vehicle. The electronic component comprises an insulator and a conductor film provided on a surface of the insulator. The conductor film is formed by firing the conductor paste provided on the surface of the insulator.

Description

卑金属粉末およびその製法、導体ペースト、ならびに電子部品Base metal powder and its manufacturing method, conductor paste, and electronic component
　本発明は、微粒の卑金属粉末およびその製法、この卑金属粉末を用いた導体ペースト、ならびにその導体ペーストを用いて形成される導体膜を備えた電子部品に関する。 The present invention relates to a fine base metal powder and a manufacturing method thereof, a conductor paste using the base metal powder, and an electronic component including a conductor film formed using the conductor paste.
　近年、電子機器の小型化および薄型化に伴い、積層セラミックコンデンサ、インダクタおよびＩＣパッケージなどの電子部品において、これらを構成する誘電体層などの絶縁体の薄層化および多層化が図られている。この絶縁体の薄層化に伴って、該絶縁体と、その表面に形成される導体膜との厚み差が小さくなってきている。その結果、前記導体膜の厚みによる段差に起因して、絶縁体と導体膜との間でデラミネーション等の不良が発生しやすくなってきている。そのため前記導体膜についても薄層化の要求が高まっており、以下に示すように、大量生産に適した液相法を用いた微粒の卑金属粉末の製法が種々提案されている。 In recent years, as electronic devices have become smaller and thinner, electronic components such as multilayer ceramic capacitors, inductors, and IC packages have been made thinner and multi-layered with insulators such as dielectric layers constituting them. . As the thickness of the insulator is reduced, the thickness difference between the insulator and the conductor film formed on the surface of the insulator is becoming smaller. As a result, defects such as delamination are likely to occur between the insulator and the conductor film due to the step due to the thickness of the conductor film. Therefore, there is an increasing demand for thinning the conductor film, and various methods for producing fine base metal powders using a liquid phase method suitable for mass production have been proposed as described below.
　特許文献１には、出発原料として水酸化ニッケルを用い、これにアルカリ土類金属の酸化物を混合し、水素還元雰囲気中にて、８００℃以上の温度に加熱することにより、１粒子の最大投影直径が５００～３０００ｎｍで、厚みが５０～９００ｎｍの扁平な形状のニッケル粉末を得る製法が記載されている。 In Patent Document 1, nickel hydroxide is used as a starting material, an alkaline earth metal oxide is mixed with the starting material, and heated to a temperature of 800 ° C. or higher in a hydrogen reducing atmosphere, whereby the maximum of one particle is obtained. A production method for obtaining a flat nickel powder having a projected diameter of 500 to 3000 nm and a thickness of 50 to 900 nm is described.
　また、特許文献２には、出発原料として塩化ニッケルを用い、これにチタンイソプロポキシド、水酸化バリウムおよび水酸化ナトリウムを加え、これらをイオン交換水に溶解させて、６０℃にて、１時間放置することにより、粒子径１００ｎｍのニッケルを主成分とする卑金属粉末を得る製法が記載されている。 Further, in Patent Document 2, nickel chloride is used as a starting material, titanium isopropoxide, barium hydroxide and sodium hydroxide are added thereto, and these are dissolved in ion-exchanged water at 60 ° C. for 1 hour. A process for obtaining a base metal powder mainly composed of nickel having a particle diameter of 100 nm is described.
　さらに、特許文献３には、出発原料として、水酸化ニッケルにパラジウムなどの貴金属を添加し、これをエチレングリコール溶液中に投入して加熱還元することにより、平均粒径が２０～１００ｎｍで、かつ粒径ばらつきの小さいニッケル粉末を得る製法が記載されている。 Further, in Patent Document 3, as a starting material, a noble metal such as palladium is added to nickel hydroxide, and this is put into an ethylene glycol solution and heated to reduce, so that the average particle diameter is 20 to 100 nm. A process for obtaining nickel powder with small particle size variation is described.
　しかしながら、これまで平均粒径が３０ｎｍ以下で、かつ高純度の卑金属粉末、および、このような超微粒で高純度の卑金属粉末を製造する方法については何ら知られていない。 However, until now, there is no known method for producing a high-purity base metal powder having an average particle diameter of 30 nm or less and such ultrafine and high-purity base metal powder.
特開平１１－１５２５０５号公報JP-A-11-152505 特開２００３－１２９１０６号公報JP 2003-129106 A 特開２００６－３３６０６０号公報JP 2006-336060 A
　本発明の課題は、超微粒の卑金属粉末と、このような超微粒の卑金属粉末を大量に生産するための製法を提供することである。また、こうして得られた超微粒の卑金属粉末を導体ペーストに用いて、絶縁体の表面に薄層の導体膜を有し、デラミネーション等の発生を抑制できる電子部品を提供することである。 An object of the present invention is to provide an ultrafine base metal powder and a production method for producing such an ultrafine base metal powder in large quantities. Another object of the present invention is to provide an electronic component that uses the ultrafine base metal powder thus obtained as a conductor paste, has a thin conductor film on the surface of the insulator, and can suppress the occurrence of delamination or the like.
　本発明の卑金属粉末は、卑金属を主成分とし、平均粒径が５～３０ｎｍである。そして、Ｘ線回折パターンにおいて、前記卑金属の六方最密構造（ｈｃｐ）の主ピークおよび前記卑金属の酸化物の主ピークのうちの強い方の回折強度が、前記卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度の１０％以下である。 The base metal powder of the present invention has a base metal as a main component and an average particle size of 5 to 30 nm. In the X-ray diffraction pattern, the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the base metal oxide main peak is a cubic close-packed structure of the base metal (ccp). Is 10% or less of the diffraction intensity of the main peak.
　本発明の卑金属粉末の製法は、以下の（ａ）～（ｃ）の工程を具備する。
（ａ）卑金属の硝酸塩と、オレイン酸ナトリウムまたはマレイン酸ナトリウムとを、水と、該水よりも極性の低い２種の溶媒との混合溶媒中に溶解して卑金属含有溶液を調製する工程。
（ｂ）該卑金属含有溶液から、前記卑金属を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る工程。
（ｃ）前記卑金属を含むオレイン酸の前駆体またはマレイン酸の前駆体を、還元雰囲気中にて、２５０～４００℃の温度で加熱する工程。 The method for producing a base metal powder of the present invention includes the following steps (a) to (c).
(A) A step of preparing a base metal-containing solution by dissolving a nitrate of base metal and sodium oleate or sodium maleate in a mixed solvent of water and two kinds of solvents having a polarity lower than that of water.
(B) A step of obtaining a precursor of oleic acid or maleic acid containing the base metal from the base metal-containing solution.
(C) A step of heating the oleic acid precursor or maleic acid precursor containing the base metal at a temperature of 250 to 400 ° C. in a reducing atmosphere.
　本発明の導体ペーストは、前記卑金属粉末と、有機ビヒクルとを含む。
　本発明の電子部品は、絶縁体と、該絶縁体の表面に設けられた導体膜とを具備する。そして、前記導体膜が、前記絶縁体の表面に設けられた前記導体ペーストを焼成して形成されている。 The conductor paste of the present invention contains the base metal powder and an organic vehicle.
The electronic component of the present invention includes an insulator and a conductor film provided on the surface of the insulator. And the said conductor film is formed by baking the said conductor paste provided in the surface of the said insulator.
　本発明の卑金属粉末および導体ペーストによれば、極めて薄い導体膜を形成できる。このため、絶縁体と導体膜とが多層に積層された電子部品において、デラミネーション等の発生を抑制できる。
　また、本発明の卑金属粉末の製法によれば、極めて薄い導体膜を形成可能な超微粒で高純度の卑金属粉末を容易に大量生産できる。
　本発明の電子部品によれば、さらなる小型化および薄型化を図ることが可能になる。 According to the base metal powder and the conductor paste of the present invention, an extremely thin conductor film can be formed. For this reason, it is possible to suppress the occurrence of delamination or the like in an electronic component in which an insulator and a conductor film are laminated in multiple layers.
Moreover, according to the manufacturing method of the base metal powder of the present invention, it is possible to easily mass-produce ultrafine and high-purity base metal powder capable of forming an extremely thin conductor film.
According to the electronic component of the present invention, it is possible to further reduce the size and thickness.
本発明の卑金属粉末の一例であるニッケル粉末の電子顕微鏡写真である。It is an electron micrograph of nickel powder which is an example of the base metal powder of the present invention. 本発明の卑金属粉末の一例であるニッケル粉末のＸ線回折パターンである。It is an X-ray-diffraction pattern of the nickel powder which is an example of the base metal powder of this invention. 本発明の卑金属粉末の製法における（ｂ）工程において、生成するオレイン酸の前駆体またはマレイン酸の前駆体が溶液中で分離した状態を示す模式図である。It is a schematic diagram which shows the state which the precursor of the oleic acid or maleic acid to produce | generate isolate | separated in the solution in the (b) process in the manufacturing method of the base metal powder of this invention. 本発明の電子部品の一例である積層セラミックコンデンサを示す断面模式図である。It is a cross-sectional schematic diagram which shows the multilayer ceramic capacitor which is an example of the electronic component of this invention.
　本実施形態の卑金属粉末は、ニッケル，銅およびコバルト等の卑金属を主成分とするものである。卑金属の成分としてはニッケルまたは銅であることが望ましい。ニッケルまたは銅は、金、銀、パラジウムおよび白金などの貴金属に比較して安価であることから、積層型の電子部品を構成する導体膜に適用した場合に製造コストを低減できるという利点がある。 The base metal powder of this embodiment is mainly composed of base metals such as nickel, copper and cobalt. The base metal component is preferably nickel or copper. Since nickel or copper is less expensive than noble metals such as gold, silver, palladium, and platinum, there is an advantage that the manufacturing cost can be reduced when applied to a conductor film constituting a multilayer electronic component.
　本実施形態の卑金属粉末は、平均粒径が５～３０ｎｍである（図１参照）。卑金属粉末の平均粒径が５ｎｍ以上であると、結晶性が高く、かつ高純度の卑金属粉末となり、不均一な反応が抑えられ、加熱時の凝集を抑制できる。また、前記平均粒径が３０ｎｍ以下であると、誘電体層等の絶縁体の表面に、きわめて薄い導体膜を形成できることから、導体膜による段差を低減できる。それゆえ、絶縁体と導体膜とが多層に積層された電子部品において、デラミネーション等の発生を抑制できる。 The base metal powder of this embodiment has an average particle size of 5 to 30 nm (see FIG. 1). When the average particle size of the base metal powder is 5 nm or more, the crystallinity is high and the base metal powder has high purity, non-uniform reaction is suppressed, and aggregation during heating can be suppressed. Further, when the average particle size is 30 nm or less, a very thin conductor film can be formed on the surface of an insulator such as a dielectric layer, so that a step due to the conductor film can be reduced. Therefore, it is possible to suppress the occurrence of delamination or the like in an electronic component in which an insulator and a conductor film are laminated in multiple layers.
　特に、卑金属粉末の平均粒径としては７～１０ｎｍが好ましい。平均粒径がこの範囲であると、卑金属粉末の反応性をより安定化できることから凝集が抑制され、薄層化が可能になる。 In particular, the average particle diameter of the base metal powder is preferably 7 to 10 nm. When the average particle size is within this range, the reactivity of the base metal powder can be further stabilized, so that aggregation is suppressed and thinning is possible.
　これに対して、卑金属粉末の平均粒径が５ｎｍよりも小さいと、結晶性が低くなり、立方最密構造（ｃｃｐ）の割合が低下する。さらには、卑金属粉末の形状が不揃いになりやすいことから、不均一な反応が起こりやすくなる。このため凝集しやくなり、その結果、導体膜を薄層化することが困難となる。 On the other hand, when the average particle diameter of the base metal powder is smaller than 5 nm, the crystallinity is lowered and the ratio of the cubic close-packed structure (ccp) is lowered. Furthermore, since the shape of the base metal powder is likely to be uneven, a non-uniform reaction is likely to occur. For this reason, it becomes easy to aggregate, and as a result, it becomes difficult to make a conductor film thin.
　また、卑金属粉末の平均粒径が３０ｎｍよりも大きいと、誘電体層等の絶縁体の表面に薄層の導体膜を形成することが困難となる。このため、絶縁体と導体膜とが多層に積層された電子部品において、導体膜の厚みによる段差が大きくなり、デラミネーション等の不良が発生しやすくなる。 If the average particle size of the base metal powder is larger than 30 nm, it is difficult to form a thin conductor film on the surface of an insulator such as a dielectric layer. For this reason, in an electronic component in which an insulator and a conductor film are laminated in multiple layers, a step due to the thickness of the conductor film is increased, and defects such as delamination are likely to occur.
　前記平均粒径は、後述するように、走査型電子顕微鏡を用いて測定される値である。また、前記平均粒径は、後述する本実施形態の製法において、例えば（ｃ）工程における還元雰囲気中の加熱温度を調節することによって、所望の値に制御することができる。 The average particle diameter is a value measured using a scanning electron microscope, as will be described later. Moreover, the said average particle diameter can be controlled to a desired value in the manufacturing method of this embodiment mentioned later by adjusting the heating temperature in the reducing atmosphere in (c) process, for example.
　本実施形態の卑金属粉末は、Ｘ線回折パターンにおいて、前記卑金属の六方最密構造（ｈｃｐ）の主ピークおよび前記卑金属の酸化物の主ピークのうちの強い方の回折強度が、前記卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度の１０％以下である。 In the X-ray diffraction pattern, the base metal powder of the present embodiment has a diffraction intensity of the stronger one of the main peak of the base metal hexagonal close-packed structure (hcp) and the main peak of the base metal oxide in the base metal cubic. It is 10% or less of the diffraction intensity of the main peak of the closest packed structure (ccp).
　具体例を挙げると、図２は、本実施形態の卑金属粉末の一例であるニッケル粉末のＸ線回折パターンである。図２に示すＸ線回折パターンのうち（ａ）は、後述する実施例における試料Ｎｏ．３の加熱温度が２５０℃の場合、（ｂ）は、実施例における試料Ｎｏ．６の加熱温度が４００℃の場合である。 As a specific example, FIG. 2 is an X-ray diffraction pattern of nickel powder which is an example of the base metal powder of this embodiment. Among the X-ray diffraction patterns shown in FIG. When the heating temperature of No. 3 is 250 ° C., FIG. This is a case where the heating temperature of 6 is 400 ° C.
　同図に示すように、本実施形態の卑金属粉末は、Ｘ線回折パターンにおいて、卑金属（ニッケル：Ｎｉ）の六方最密構造（ｈｃｐ）の主ピーク（１１１）および卑金属の酸化物（酸化ニッケル：ＮｉＯ）の主ピーク（２００）のうちの強い方の回折強度が、卑金属の立方最密構造（ｃｃｐ）の主ピーク（１１１）の回折強度の１０％以下である。 As shown in the figure, the base metal powder of the present embodiment has a base metal (nickel: Ni) hexagonal close-packed structure (hcp) main peak (111) and base metal oxide (nickel oxide: nickel oxide) in an X-ray diffraction pattern. The stronger diffraction intensity of the main peak (200) of NiO) is 10% or less of the diffraction intensity of the main peak (111) of the base metal cubic close-packed structure (ccp).
　本実施形態の卑金属粉末は、上述のような平均粒径を有していても、金属として高い最密充填構造を有する立方最密構造の割合が多いために、金属のすべり面が現れやすいことから展性や延性に富み、かつ導電性の高いものを得ることができる。 Even if the base metal powder of this embodiment has the average particle size as described above, since the ratio of the cubic close-packed structure having a high close-packed structure as a metal is large, a metal slip surface is likely to appear. Therefore, it is possible to obtain a highly conductive material having high malleability and ductility.
　特に、卑金属の六方最密構造（ｈｃｐ）の主ピークおよび卑金属の酸化物の主ピークのうちの強い方の回折強度が、卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度の５％以下であることがより望ましく、その卑金属粉末における卑金属の含有量は９９％以上であることが好ましい。これにより、卑金属粉末の焼結体中における異相の生成を抑制でき、展性や延性および導電性を高めることが可能になる。 In particular, the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the main peak of the base metal oxide is 5% of the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp). More preferably, the content of the base metal in the base metal powder is preferably 99% or more. Thereby, the production | generation of the heterogeneous phase in the sintered compact of base metal powder can be suppressed, and it becomes possible to improve malleability, ductility, and electroconductivity.
　これに対して、卑金属の六方最密構造（ｈｃｐ）の主ピークおよび卑金属の酸化物の主ピークのうちの強い方の回折強度が、卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度に対して１０％よりも高いと、展性や延性および高い導電率を得ることが困難となる。 On the other hand, the stronger diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the base peak of the base metal oxide is the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp). On the other hand, if it is higher than 10%, it becomes difficult to obtain malleability, ductility and high electrical conductivity.
　前記Ｘ線回折パターンにおける回折強度は、後述するように、Ｘ線回折装置を用いて測定される値である。また、卑金属の六方最密構造（ｈｃｐ）の主ピークおよび卑金属の酸化物の主ピークのうちの強い方の回折強度を、卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度の１０％以下とするには、本実施形態の製法において、例えば（ｃ）工程における還元雰囲気中の加熱温度を調節することによって、所望の値に制御することができる。 The diffraction intensity in the X-ray diffraction pattern is a value measured using an X-ray diffractometer, as will be described later. The diffraction intensity of the stronger one of the main peak of the base metal hexagonal close-packed structure (hcp) and the base peak of the base metal oxide is 10% of the diffraction intensity of the main peak of the base metal cubic close-packed structure (ccp). In order to make the following, in the manufacturing method of the present embodiment, for example, the heating temperature in the reducing atmosphere in the step (c) can be adjusted to a desired value.
　次に、本実施形態の卑金属粉末の製法について説明する。本実施形態の卑金属粉末の製法は、以下の（ａ）～（ｃ）の工程を具備する。
　（ａ）工程では、図３に示すガラス製容器１０に、卑金属の硝酸塩と、オレイン酸ナトリウムまたはマレイン酸ナトリウムとを入れる。さらに水と、該水よりも極性の低い２種の溶媒とを加えて、これら３種の混合溶媒中に卑金属の成分が溶解した卑金属含有溶液を調製する。 Next, the manufacturing method of the base metal powder of this embodiment is demonstrated. The method for producing a base metal powder of the present embodiment includes the following steps (a) to (c).
In step (a), base metal nitrate and sodium oleate or sodium maleate are placed in a glass container 10 shown in FIG. Further, water and two kinds of solvents having a polarity lower than that of water are added to prepare a base metal-containing solution in which base metal components are dissolved in these three kinds of mixed solvents.
　前記卑金属の硝酸塩としては、硝酸ニッケル、硝酸銅または硝酸コバルトを用いるのが好ましく、硝酸ニッケルまたは硝酸銅を用いるのがより好ましい。これらの硝酸塩は水和物であっても良いが、高純度の卑金属粉末が得られるという理由から、用いる硝酸塩の純度は９９％以上であることが好ましい。 As the base metal nitrate, nickel nitrate, copper nitrate or cobalt nitrate is preferably used, and nickel nitrate or copper nitrate is more preferably used. These nitrates may be hydrates, but the purity of the nitrate used is preferably 99% or more because high-purity base metal powder can be obtained.
　また、添加剤として、オレイン酸ナトリウムまたはマレイン酸ナトリウムを、硝酸塩１００質量部に対して５～２０質量部添加するのが好ましい。これにより、反応終了後に生成する卑金属を含む前駆体の凝集を抑制できるとともに、前駆体を構成する有機物の分解反応を促進でき、微粒の卑金属粉末が得られるという利点がある。 Further, it is preferable to add 5 to 20 parts by mass of sodium oleate or sodium maleate as an additive with respect to 100 parts by mass of nitrate. Thereby, it is possible to suppress aggregation of the precursor containing the base metal generated after the completion of the reaction, promote the decomposition reaction of the organic matter constituting the precursor, and obtain a fine base metal powder.
　また、本実施形態の卑金属粉末の製法では、上記卑金属を含む硝酸塩を溶解させ、かつ反応終了後に卑金属を含む前駆体を形成するための溶媒として、上述の通り、水と、該水よりも極性の低い２種の溶媒とを用いる。以下、水を第１の溶媒、該水よりも極性の低い２種の溶媒を第２，第３の溶媒として説明する。 Further, in the method for producing a base metal powder of the present embodiment, as described above, water and a polar than the water are used as a solvent for dissolving the nitrate containing the base metal and forming a precursor containing the base metal after the reaction is completed. And two low solvents. Hereinafter, water is described as a first solvent, and two kinds of solvents having a polarity lower than that of water are described as second and third solvents.
　第１の溶媒である水（極性：２１）は、イオン交換水を用いるのが良い。水よりも極性の低い溶媒である第２の溶媒としては、ブチルアルコール（極性：１０．７）、ヘキサン（極性：７．３）およびオクタン（極性：７．０）から選ばれる１種の溶媒を用いることが好ましい。なお、溶媒の極性とは、成分原子の電気陰性度の違いのために電子雲の分布が偏り、正負の電荷の重心が一致せずに双極子が形成された状態を表す量であり、溶媒のモル蒸発エネルギーを１モル当たりの体積で除した値の平方根で表される値である。 The first solvent, water (polarity: 21), is preferably ion-exchanged water. As the second solvent which is a solvent having a polarity lower than that of water, one solvent selected from butyl alcohol (polarity: 10.7), hexane (polarity: 7.3) and octane (polarity: 7.0) Is preferably used. The polarity of the solvent is an amount representing a state in which the distribution of the electron cloud is biased due to the difference in electronegativity of the component atoms, and the dipole is formed without the center of gravity of the positive and negative charges being matched. This is a value represented by the square root of the value obtained by dividing the molar evaporation energy by the volume per mole.
　また、水よりも極性の低い第３の溶媒としては、水と第２の溶媒との中間の極性を持つ溶媒を選択するのがよく、例えば、メチルアルコール、エチルアルコールおよびプロピルアルコールから選ばれる１種の溶媒を用いることが好ましい。 In addition, as the third solvent having a polarity lower than that of water, a solvent having an intermediate polarity between water and the second solvent is preferably selected. For example, 1 selected from methyl alcohol, ethyl alcohol, and propyl alcohol. It is preferred to use a seed solvent.
　本実施形態の製法において、極性の異なる３種の溶媒を用いるのは以下の理由からである。すなわち、第１の溶媒として、極性の高い水を用いるのは、卑金属を含む硝酸塩を溶解し易く、また、後述のオレイン酸ナトリウムまたはマレイン酸ナトリウムに含まれるナトリウム成分を水に溶解させておくことができるからである。 In the manufacturing method of the present embodiment, three types of solvents having different polarities are used for the following reason. That is, the use of highly polar water as the first solvent facilitates the dissolution of nitrates containing base metals, and also dissolves the sodium component contained in sodium oleate or sodium maleate described below in water. Because you can.
　第２の溶媒として水よりも極性の低いブチルアルコール、ヘキサンおよびオクタンから選ばれる１種の溶媒を用いるのは、上述のオレイン酸ナトリウムまたはマレイン酸ナトリウムが溶解しやすく、またオレイン酸ナトリウムまたはマレイン酸ナトリウムを核として形成される卑金属を含むオレイン酸の前駆体またはマレイン酸の前駆体が形成されやすいからである。 The use of one solvent selected from butyl alcohol, hexane, and octane, which is less polar than water, as the second solvent facilitates dissolution of the above-mentioned sodium oleate or sodium maleate, and also provides sodium oleate or maleic acid. This is because an oleic acid precursor or a maleic acid precursor containing a base metal formed with sodium as a nucleus is easily formed.
　さらに、水と第２の溶媒との中間の極性を有する第３の溶媒を用いるのは、第１の溶媒である水と第２の溶媒であるメチルアルコール（極性：１２．９）、エチルアルコール（極性：１１．２）およびプロピルアルコール（極性：１１．５）から選ばれる１種の溶媒とを分離することなく均一に混合するためである。これにより、水に溶解しやすい卑金属の硝酸塩と第２の溶媒に溶解しやすいオレイン酸ナトリウムまたはマレイン酸ナトリウムとを均一に混合することが可能になる。 Furthermore, the third solvent having a polarity intermediate between water and the second solvent uses water as the first solvent and methyl alcohol (polarity: 12.9) as the second solvent, ethyl alcohol. (Polarity: 11.2) and one solvent selected from propyl alcohol (polarity: 11.5) are mixed uniformly without separation. This makes it possible to uniformly mix base metal nitrate that is easily dissolved in water and sodium oleate or sodium maleate that is easily dissolved in the second solvent.
　（ｂ）工程では、卑金属含有溶液を静かに放置して、図３に示すように、卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０を得る。卑金属含有溶液を静かに放置することにより、卑金属含有溶液は、水２１と、ブチルアルコール、ヘキサンおよびオクタンから選ばれる１種の溶媒との間で分離していき、生成するオレイン酸の前駆体２０またはマレイン酸の前駆体２０が第２の溶媒中に生成する。このときオレイン酸の前駆体２０およびマレイン酸の前駆体２０は重合体となっている。 In the step (b), the base metal-containing solution is gently left to obtain an oleic acid precursor 20 or a maleic acid precursor 20 containing a base metal, as shown in FIG. By leaving the base metal-containing solution gently, the base metal-containing solution is separated between the water 21 and one solvent selected from butyl alcohol, hexane, and octane. Alternatively, a maleic acid precursor 20 is formed in the second solvent. At this time, the precursor 20 of oleic acid and the precursor 20 of maleic acid are polymers.
　卑金属含有溶液を静かに放置するときの条件は、卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０の収率を高めるとともに、これらの前駆体２０の加熱による分解性を高めるという理由から、温度１０～５０℃にて１～４８時間が好ましい。 The reason why the base metal-containing solution is allowed to stand gently is to increase the yield of the oleic acid precursor 20 or maleic acid precursor 20 containing the base metal, and to increase the decomposability of these precursors 20 by heating. Therefore, 1 to 48 hours at a temperature of 10 to 50 ° C. is preferable.
　次に、ガラス製容器１０の排出口１１を開けて分離した下層側の溶液を排出し、卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０を含む第２の溶媒のみを抽出する。この後、卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０を含む溶液から溶媒を乾燥させて卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０を得る。 Next, the lower layer solution separated by opening the discharge port 11 of the glass container 10 is discharged, and only the second solvent containing the oleic acid precursor 20 containing the base metal or the maleic acid precursor 20 is extracted. . Thereafter, the solvent is dried from the solution containing the base metal-containing oleic acid precursor 20 or the maleic acid precursor 20 to obtain the base metal-containing oleic acid precursor 20 or the maleic acid precursor 20.
　次に、（ｃ）工程では、得られた卑金属を含むオレイン酸の前駆体２０またはマレイン酸の前駆体２０を、還元雰囲気（Ｎ２／５％Ｈ２）中にて２５０～４００℃の温度で加熱する。これにより、超微粒で高純度の本実施形態の卑金属粉末が得られる。また、このような（ａ）～（ｃ）の工程を具備する本実施形態の卑金属粉末の製法は、大量生産に適している。 Next, in the step (c), the obtained oleic acid precursor 20 or maleic acid precursor 20 containing the base metal is heated at a temperature of 250 to 400 ° C. in a reducing atmosphere (N 2 /5% H 2 ). Heat with. Thereby, the base metal powder of this embodiment with ultrafine particles and high purity is obtained. Further, the base metal powder manufacturing method of the present embodiment including the steps (a) to (c) is suitable for mass production.
　特に、得られる卑金属粉末において、立方最密構造（ｃｃｐ）の割合が高く、平均粒径を７～１０ｎｍにできるという点で、加熱する温度は２７０～３７０℃が好ましく、３００～３５０℃がより好ましい。 In particular, in the obtained base metal powder, the heating temperature is preferably 270 to 370 ° C., more preferably 300 to 350 ° C. in that the ratio of the cubic close-packed structure (ccp) is high and the average particle size can be 7 to 10 nm. preferable.
　これに対して、加熱する温度が２５０℃よりも低くなると、オレイン酸の前駆体２０またはマレイン酸の前駆体２０の分解反応が促進されず前駆体２０が残留しやすくなる。また、加熱する温度が４００℃よりも高いと、オレイン酸の前駆体２０またはマレイン酸の前駆体２０の分解反応が進み、残留する前駆体２０の量は少なくなるものの、得られる卑金属粉末が粒成長するため、超微粒の卑金属粉末を得ることが困難となる。 On the other hand, when the heating temperature is lower than 250 ° C., the decomposition reaction of the precursor 20 of oleic acid or the precursor 20 of maleic acid is not accelerated and the precursor 20 tends to remain. Further, when the heating temperature is higher than 400 ° C., the decomposition reaction of the precursor 20 of oleic acid or the precursor 20 of maleic acid proceeds and the amount of the remaining precursor 20 is reduced, but the obtained base metal powder is granulated. Since it grows, it becomes difficult to obtain ultrafine base metal powder.
　次に、本実施形態の卑金属粉末を用いて得られる導体ペーストについて説明する。本実施形態の導体ペーストは、上記卑金属粉末と有機ビヒクルとを含むものである。前記有機ビヒクルとしては、例えばエチルセルロース等のセルロース系高分子、エチレングリコールおよびジエチレングリコール誘導体、トルエン、キシレン、ミネラルスピリット、ブチルカルビトール、α－テルピネオール（ターピネオール）等の有機溶媒が挙げられ、これらは１種または２種以上を混合して用いてもよい。 Next, the conductor paste obtained using the base metal powder of this embodiment will be described. The conductor paste of this embodiment contains the base metal powder and the organic vehicle. Examples of the organic vehicle include cellulosic polymers such as ethyl cellulose, organic solvents such as ethylene glycol and diethylene glycol derivatives, toluene, xylene, mineral spirits, butyl carbitol, and α-terpineol (terpineol). Alternatively, two or more kinds may be mixed and used.
　また、前記導体ペーストには、必要に応じて、導体ペースト本来の導電性（低抵抗率）、半田耐熱性、接着強度等を著しく損なわない限りにおいて、種々の無機添加剤を副成分として含ませることができる。前記無機添加剤としては、例えばガラス粉末、無機酸化物、その他種々のフィラー等が挙げられる。この場合、無機添加剤は、平均粒径が卑金属粉末と同等か、もしくはそれ以下の平均粒径を有するものが好ましい。 In addition, the conductive paste may contain various inorganic additives as subcomponents as necessary as long as the original conductivity (low resistivity), solder heat resistance, adhesive strength, etc. of the conductive paste are not significantly impaired. be able to. Examples of the inorganic additive include glass powder, inorganic oxide, and various other fillers. In this case, the inorganic additive preferably has an average particle diameter equal to or less than that of the base metal powder.
　導体ペーストの調製は、例えば３本ロールミルやその他の混練機を用いて、卑金属粉末および各種添加剤を有機ビヒクルとともに所定の配合比で直接混合し、相互に練り合わせればよい。 The conductive paste may be prepared by, for example, directly mixing the base metal powder and various additives together with the organic vehicle at a predetermined mixing ratio using a three-roll mill or other kneader, and kneading them together.
　導体ペースト中の卑金属粉末の含有量は、特に限定されるものではないが、主成分たる卑金属粉末の含有率が、ペースト全体の６０～９５質量％となるように各材料を混練するのがよい。 The content of the base metal powder in the conductor paste is not particularly limited, but each material is preferably kneaded so that the content of the base metal powder as the main component is 60 to 95% by mass of the entire paste. .
　導体ペーストの調製に用いられる有機ビヒクルの添加量は、ペースト全体のほぼ１～４０質量％となる量が適当であり、１～２０質量％となる量が特に好ましい。また、無機添加剤としてガラス粉末やセラミック粉末を加える場合には、卑金属粉末１００質量部に対して５質量部以下の割合で添加するのが好ましい。 The amount of the organic vehicle used for the preparation of the conductor paste is suitably about 1 to 40% by mass, particularly preferably 1 to 20% by mass of the entire paste. Moreover, when adding glass powder and ceramic powder as an inorganic additive, it is preferable to add in the ratio of 5 mass parts or less with respect to 100 mass parts of base metal powder.
　次に、本実施形態の電子部品について、図４に示す積層セラミックコンデンサを例に挙げて説明する。本実施形態の導体ペーストを用いて、以下のような積層セラミックコンデンサを形成できる。 Next, the electronic component of this embodiment will be described by taking the multilayer ceramic capacitor shown in FIG. 4 as an example. The following multilayer ceramic capacitor can be formed using the conductor paste of the present embodiment.
　本実施形態における積層セラミックコンデンサは、図４に示すように、コンデンサ本体１の両端部に外部電極２が設けられている。コンデンサ本体１は、絶縁体である誘電体層３と導体膜である内部電極層４とが交互に積層され構成されている。 As shown in FIG. 4, the multilayer ceramic capacitor in the present embodiment is provided with external electrodes 2 at both ends of the capacitor body 1. The capacitor body 1 is configured by alternately laminating dielectric layers 3 that are insulators and internal electrode layers 4 that are conductor films.
　内部電極層４は、上述した本実施形態の導体ペーストによって形成されたものであり、その厚みは誘電体層３の厚みが１μｍ以下である場合に、１００ｎｍ以下、特に、５０ｎｍ以下であることが望ましい。これにより、本実施形態の卑金属粉末を用いて得られる電子部品を薄型にでき、導体膜による段差を低減でき、デラミネーション等の発生を抑制することが可能になる。 The internal electrode layer 4 is formed of the above-described conductor paste of the present embodiment, and the thickness thereof is 100 nm or less, particularly 50 nm or less when the thickness of the dielectric layer 3 is 1 μm or less. desirable. Thereby, the electronic component obtained using the base metal powder of this embodiment can be made thin, the level | step difference by a conductor film can be reduced, and generation | occurrence | production of delamination etc. can be suppressed.
　次に、前記積層セラミックコンデンサの製法について説明する。
　まず、上述の導体ペーストを、焼成後に絶縁体となるセラミックグリーンシート上に印刷し、焼成後に導体膜となる導体パターンを形成する。このとき導体パターンの乾燥後の厚みは１００ｎｍ以下、特に、５０ｎｍ以下が好ましい。次いで、上述の導体パターンが形成されたセラミックグリーンシートを複数層積層し、加圧加熱して一体化させて母体積層体を形成する。 Next, a method for manufacturing the multilayer ceramic capacitor will be described.
First, the above-described conductor paste is printed on a ceramic green sheet that becomes an insulator after firing, and a conductor pattern that becomes a conductor film after firing is formed. At this time, the thickness of the conductor pattern after drying is preferably 100 nm or less, particularly preferably 50 nm or less. Next, a plurality of ceramic green sheets on which the above-described conductor pattern is formed are stacked, and are heated and integrated to form a base laminate.
　次に、得られた母体積層体を所定の寸法に切断し、焼成後にコンデンサ本体１となる未焼成の積層体を得る。次に、この未焼成の積層体を、大気中もしくは窒素雰囲気中にて脱脂した後、水素－窒素の混合ガスの還元雰囲気中にて１０００～１３００℃の範囲で１～５時間の条件で焼成する。なお、必要に応じて、焼成温度よりも低い温度（９００～１１００℃）にて再加熱して酸化処理を行ってもよい。 Next, the obtained base laminate is cut into a predetermined size to obtain an unsintered laminate that becomes the capacitor body 1 after firing. Next, this unfired laminate is degreased in the air or in a nitrogen atmosphere, and then fired in a reducing atmosphere of a hydrogen-nitrogen mixed gas at a temperature of 1000 to 1300 ° C. for 1 to 5 hours. To do. If necessary, the oxidation treatment may be performed by reheating at a temperature lower than the firing temperature (900 to 1100 ° C.).
　こうして絶縁体である誘電体層３と導体膜である内部電極層４とが交互に積層され一体化されたコンデンサ本体１が得られる。次に、このコンデンサ本体１の対向する端部に、外部電極ペーストを塗布して焼付けを行い外部電極２が形成される。また、この外部電極２の表面に実装性を高めるためのメッキ膜を形成して積層セラミックコンデンサを得る。 Thus, the capacitor body 1 in which the dielectric layers 3 as insulators and the internal electrode layers 4 as conductor films are alternately laminated and integrated is obtained. Next, an external electrode paste is applied to the opposite end portions of the capacitor body 1 and baked to form the external electrodes 2. Also, a plated film for improving the mountability is formed on the surface of the external electrode 2 to obtain a multilayer ceramic capacitor.
　以下、実施例を挙げて本発明についてさらに詳細に説明するが、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.
＜卑金属粉末の調製＞
　まず、金属源として、硝酸ニッケル（Ｎｉ（ＮＯ３）２）、硝酸銅（Ｃｕ（ＮＯ３）２）、および硝酸コバルト（Ｃｏ（ＮＯ３）２）を準備した。次に、この金属源と、表１に示す各種溶媒および添加剤とをガラス製容器に投入し、室温（２５℃）にて混合して卑金属含有溶液を調製した。これらの混合割合は、金属源としての硝酸塩１００質量部に対して、添加剤を１０質量部とし、これに第１の溶媒としてイオン交換水を２００質量部とし、表１に示した第２の溶媒および第３の溶媒の添加量はそれぞれ３００質量部とした。その後、３５℃で、５時間放置して、卑金属含有溶液を上下２層に分離させて、上部側の溶液中にオレイン酸の前駆体またはマレイン酸の前駆体を形成した。 <Preparation of base metal powder>
First, nickel nitrate (Ni (NO 3 ) 2 ), copper nitrate (Cu (NO 3 ) 2 ), and cobalt nitrate (Co (NO 3 ) 2 ) were prepared as metal sources. Next, this metal source and various solvents and additives shown in Table 1 were put into a glass container and mixed at room temperature (25 ° C.) to prepare a base metal-containing solution. The mixing ratio is 10 parts by mass of the additive with respect to 100 parts by mass of the nitrate as the metal source, and 200 parts by mass of ion-exchanged water as the first solvent. The addition amounts of the solvent and the third solvent were 300 parts by mass, respectively. The base metal-containing solution was then separated into two upper and lower layers at 35 ° C. for 5 hours to form an oleic acid precursor or maleic acid precursor in the upper solution.
　次に、ガラス製容器の下部側の排出口を開けて容器の下層側の溶媒を排出した。次いで、オレイン酸の前駆体またはマレイン酸の前駆体を含む溶液からデカンテーションにより溶媒を排出して、オレイン酸の前駆体またはマレイン酸の前駆体を得た。 Next, the lower side of the glass container was opened to discharge the solvent on the lower side of the container. Next, the solvent was discharged from the solution containing the oleic acid precursor or the maleic acid precursor by decantation to obtain an oleic acid precursor or a maleic acid precursor.
　次に、得られたオレイン酸の前駆体またはマレイン酸の前駆体を石英製容器に入れ、これを加熱炉内に置き、Ｎ２－５％Ｈ２の混合ガスを供給して、表１に示す温度に加熱して、前駆体を分解させて卑金属粉末を得た（表１中の試料Ｎｏ．１～２０）。そして、得られた卑金属粉末の平均粒径を求め、またＸ線回折パターンにより結晶構造および異相の割合を求めた。表１に結果を示すとともに、各評価方法を以下に示す。 Next, the obtained precursor of oleic acid or maleic acid was placed in a quartz vessel, placed in a heating furnace, and a mixed gas of N 2 -5% H 2 was supplied. The precursor was decomposed by heating to the indicated temperature to obtain base metal powder (Sample Nos. 1 to 20 in Table 1). And the average particle diameter of the obtained base metal powder was calculated | required, and the crystal structure and the ratio of the different phase were calculated | required by the X-ray diffraction pattern. While showing a result in Table 1, each evaluation method is shown below.
＜評価＞
（平均粒径）
　得られた卑金属粉末の平均粒径は、まず、走査型電子顕微鏡を用いて内部組織の写真を撮り（倍率：２００，０００倍）、その写真上で結晶粒子が３０個入る円を描いた。次に、該円内および円周にかかった結晶粒子を選択し、各結晶粒子の輪郭を画像処理し、各粒子を円と見立てて円相当径を算出し、その平均値より前記平均粒径を求めた。 <Evaluation>
(Average particle size)
Regarding the average particle diameter of the obtained base metal powder, first, a photograph of the internal structure was taken using a scanning electron microscope (magnification: 200,000 times), and a circle containing 30 crystal particles was drawn on the photograph. Next, select the crystal particles in and around the circle, image processing the contour of each crystal particle, calculate the equivalent circle diameter by assuming each particle as a circle, the average particle diameter from the average value Asked.
（Ｘ線回折パターン）
　卑金属粉末についての、立方最密構造（ｃｃｐ）の主ピーク（１１１）のＸ線回折強度に対する六方最密構造（ｈｃｐ）の主ピーク（１１１）および卑金属の酸化物の主ピーク（ニッケル：（２００），銅：（１１１））のうちの強い方の回折強度は、Ｘ線回折装置（Ｃｕｋα）を用いて、２θ＝３０～８０°の範囲にて回折し、Ｘ線回折装置に付設のコンピュータに出力される回折強度値から求めた。 (X-ray diffraction pattern)
Main peak (111) of hexagonal close-packed structure (hcp) and main peak of oxide of base metal (nickel: (200) with respect to X-ray diffraction intensity of main peak (111) of cubic close-packed structure (ccp) for base metal powder ), Copper: (111)) is diffracted in the range of 2θ = 30 to 80 ° using an X-ray diffractometer (Cukα), and the computer attached to the X-ray diffractometer It was calculated from the diffraction intensity value output to.
＜積層セラミックコンデンサの作製・評価＞
　次に、上記した卑金属粉末を用いて導体ペーストを調製し、この導体ペーストを内部電極用のペーストに用いて積層セラミックコンデンサを作製した。まず、上記した卑金属粉末を４０質量％とし、有機ビヒクル（エチルセルロース：５．５質量％，α－テルピネオール９４．５重量％）を５５質量％とする配合割合とし、これに適量の溶媒（α－テルピネオール）を加えて、３本ロールミルで混練して導体ペーストを作製した。 <Production and evaluation of multilayer ceramic capacitors>
Next, a conductor paste was prepared using the above-described base metal powder, and a multilayer ceramic capacitor was produced using this conductor paste as an internal electrode paste. First, the base metal powder is 40% by mass, the organic vehicle (ethylcellulose: 5.5% by mass, α-terpineol 94.5% by weight) is 55% by mass, and an appropriate amount of solvent (α- Terpineol) was added and kneaded with a three-roll mill to prepare a conductor paste.
　次に、ニッケル粉末，銅粉末およびコバルト粉末にそれぞれ適用させる絶縁体を用意した。導体膜にニッケル粉末またはコバルト粉末を用いる場合は、絶縁体を、主成分（ＢａＴｉＯ３：９７．５モル％，ＣａＺｒＯ３：２．０モル％，ＭｎＯ：０．５モル％）１００モル部に対して、Ｙ２Ｏ３を０．５モル部添加した組成とした。銅粉末を用いる場合は、上記組成１００質量部に対してホウ珪酸ガラス粉末（ＳｉＯ２：５０モル％，Ａｌ２Ｏ３：５モル％，ＭｇＯ：３０モル％，Ｂ２Ｏ３：１０モル％，ＣａＯ：５モル％）を６０質量部の割合で加えて、それぞれセラミックスラリを調製した。 Next, insulators to be applied to nickel powder, copper powder and cobalt powder were prepared. When nickel powder or cobalt powder is used for the conductor film, the insulator is added to 100 mol parts of the main components (BaTiO 3 : 97.5 mol%, CaZrO 3 : 2.0 mol%, MnO: 0.5 mol%). in contrast, using the composition in which the Y 2 O 3 was added 0.5 parts by mole. When using copper powder, borosilicate glass powder with respect to the composition 100 parts by weight (SiO 2: 50 mol%, Al 2 O 3: 5 mol%, MgO: 30 mol%, B 2 O 3: 10 mol% , CaO: 5 mol%) was added at a ratio of 60 parts by mass to prepare ceramic slurry.
　次いで、これらのセラミックスラリをポリエステルの合成樹脂より成る帯状のキャリアフィルム上にダイコータ法で成膜し、乾燥させることにより、厚みが０．６μｍのセラミックグリーンシートを得た。 Next, these ceramics were formed on a belt-like carrier film made of a synthetic resin of polyester by a die coater method and dried to obtain a ceramic green sheet having a thickness of 0.6 μm.
　次に、このセラミックグリーンシートをキャリアフィルムから剥離し、縦２００ｍｍ、横２００ｍｍのサイズに打ち抜いた後、得られたセラミックグリーンシートの一方主面に、グラビア印刷装置を用いて、上記した導体ペーストを印刷して、印刷厚みで２０～１５０ｎｍになるように導体パターンを形成した。印刷後の導体パターンの厚みは、用いた卑金属粉末の平均粒径の１０倍以下の厚みを設定した。 Next, after peeling this ceramic green sheet from the carrier film and punching it into a size of 200 mm in length and 200 mm in width, the above-mentioned conductor paste is applied to one main surface of the obtained ceramic green sheet using a gravure printing device. A conductor pattern was formed by printing so that the printed thickness was 20 to 150 nm. The thickness of the conductor pattern after printing was set to a thickness of 10 times or less the average particle diameter of the used base metal powder.
　次に、導体パターンが形成されたセラミックグリーンシートを３６０枚積層し、その上下面に導体パターンを印刷していないセラミックグリーンシートをそれぞれ２０枚積層し、プレス機を用いて温度６０℃、圧力１０７Ｐａ、時間１０分の条件で一括積層し、所定の寸法に切断し、未焼成の積層体を得た。 Next, 360 ceramic green sheets on which conductor patterns are formed are stacked, 20 ceramic green sheets on which no conductor patterns are printed are stacked on each of the upper and lower surfaces, and the temperature is 60 ° C. and the pressure is 10 using a press. Lamination was performed under the conditions of 7 Pa and time 10 minutes, and cut into predetermined dimensions to obtain an unfired laminate.
　次に、この未焼成の積層体を、大気中にて４００℃までの温度範囲で脱脂を行い、還元雰囲気中にて焼成した。導体膜を、ニッケル粉末を含む導体ペーストで形成する場合には１２５０℃で、コバルト粉末を含む導体ペーストで形成する場合には約１２００℃で、銅粉末を含む導体ペーストで形成する場合には９２０℃でそれぞれ２時間焼成してコンデンサ本体を得た。 Next, this unfired laminate was degreased in the temperature range up to 400 ° C. and fired in a reducing atmosphere. The conductor film is formed at 1250 ° C. when formed with a conductor paste containing nickel powder, at about 1200 ° C. when formed with a conductor paste containing cobalt powder, and 920 when formed with a conductor paste containing copper powder. The capacitor body was obtained by firing at 2 ° C. for 2 hours.
　このようにして得られたコンデンサ本体の外形寸法は、長さ３．２ｍｍ、幅１．６ｍｍ、厚さ１．０ｍｍであり、内部電極層間に介在する誘電体層の厚みは０．４μｍであった。また、誘電体層の一層当たりの対向内部電極層の有効面積は２．１ｍｍ２であった。 The external dimensions of the capacitor body thus obtained are 3.2 mm in length, 1.6 mm in width, and 1.0 mm in thickness, and the thickness of the dielectric layer interposed between the internal electrode layers is 0.4 μm. It was. The effective area of the counter internal electrode layer per layer of the dielectric layer was 2.1 mm 2 .
　上述のようにして得られたコンデンサ本体を、各試料１００個ずつ樹脂で固めて研磨し、倍率４００倍の金属顕微鏡観察を行って、デラミネーションの有無を検査した。表１に結果を示す。 The capacitor body obtained as described above was solidified with 100 samples of each sample and polished, and observed with a metal microscope at a magnification of 400 times to inspect for delamination. Table 1 shows the results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果から明らかなように、本発明の製法により得られた卑金属粉末（試料Ｎｏ．３～６，８～１２，１５～１８および２０）は、平均粒径が５～３０ｎｍであり、立方最密構造（ｃｃｐ）の主ピーク（１１１）の回折強度に対する六方最密構造（ｈｃｐ）の主ピーク（１１１）および卑金属の酸化物の主ピーク（２００）のうちの強い方の回折強度が１０％以下であった。 As is apparent from the results in Table 1, the base metal powders (samples Nos. 3 to 6, 8 to 12, 15 to 18 and 20) obtained by the production method of the present invention have an average particle size of 5 to 30 nm. The diffraction intensity of the stronger one of the main peak (111) of the hexagonal close-packed structure (hcp) and the main peak (200) of the base metal oxide with respect to the diffraction intensity of the main peak (111) of the cubic close-packed structure (ccp) It was 10% or less.
　また、図２から明らかなように、本発明の卑金属粉末である試料Ｎｏ．３，６は、高純度であることがわかる。これと同様に、本発明にかかる他の卑金属粉末についても、Ｘ線回折パターンの結果から、高純度であることを確認できた。 Further, as is apparent from FIG. 2, the sample No. which is the base metal powder of the present invention. 3 and 6 are found to be highly pure. Similarly to this, it was confirmed that the other base metal powder according to the present invention was of high purity from the result of the X-ray diffraction pattern.
　また、このような超微粒の本発明にかかる卑金属粉末を用いて作製した積層セラミックコンデンサでは、内部電極層の周囲に段差解消用のセラミックパターンを形成しなくても、３６０層の積層体においてデラミネーションの発生数が１００個中１個以下であった。 In addition, in the multilayer ceramic capacitor produced using such ultrafine base metal powder according to the present invention, a 360-layer laminate can be used without forming a step-resolving ceramic pattern around the internal electrode layer. The number of laminations was 1 or less out of 100.
　特に、本発明の製法により得られたオレイン酸の前駆体およびマレイン酸前駆体を３００～３５０℃で加熱した試料Ｎｏ．４，５，８～１２，１６，１７および２０は、卑金属粉末の平均粒径が１０ｎｍ以下であり、立方最密構造（ｃｃｐ）の主ピーク（１１１）の回折強度に対する六方最密構造（ｈｃｐ）の主ピーク（１１１）および卑金属の酸化物の主ピーク（２００）のうちの強い方の回折強度が７％以下であり、また、３６０層の積層体においてもデラミネーションの発生数が無かった。 In particular, sample Nos. Obtained by heating the oleic acid precursor and maleic acid precursor obtained by the production method of the present invention at 300 to 350 ° C. Nos. 4, 5, 8 to 12, 16, 17, and 20 have an average particle diameter of the base metal powder of 10 nm or less, and a hexagonal close-packed structure (hcp) with respect to the diffraction intensity of the main peak (111) of the cubic close-packed structure (ccp). The diffraction intensity of the stronger one of the main peak (111) and the main peak (200) of the base metal oxide is 7% or less, and no delamination occurred in the 360-layer laminate. .
　これに対して、オレイン酸の前駆体を２００℃で加熱した試料Ｎｏ．１，１３は、前駆体の残留があった。また、前記前駆体を２３０℃で加熱した試料Ｎｏ．２，１４においても、六方最密構造（ｈｃｐ）の（１１１）のピークもしくは卑金属の酸化物の（２００）ピークのうち強い方のピーク強度が１７％以上であった。また、加熱の温度を４００℃よりも高くした試料Ｎｏ．７，１９では、卑金属粉末の平均粒径が３０ｎｍを遙かに越えるものとなり、評価したコンデンサ本体においてデラミネーションの発生割合が１００個中１０個もあった。 In contrast, sample No. 1 was obtained by heating a precursor of oleic acid at 200 ° C. 1 and 13 had precursors remaining. In addition, Sample No. obtained by heating the precursor at 230 ° C. 2 and 14, the stronger peak intensity of the (111) peak of the hexagonal close-packed structure (hcp) or the (200) peak of the base metal oxide was 17% or more. In addition, Sample No. with heating temperature higher than 400 ° C was used. In Nos. 7 and 19, the average particle size of the base metal powder far exceeded 30 nm, and the evaluated capacitor body had a delamination generation rate of 10 out of 100.

Claims (8)

  1. 　卑金属を主成分とし、
    平均粒径が５～３０ｎｍであり、
    Ｘ線回折パターンにおいて、前記卑金属の六方最密構造（ｈｃｐ）の主ピークおよび前記卑金属の酸化物の主ピークのうちの強い方の回折強度が、前記卑金属の立方最密構造（ｃｃｐ）の主ピークの回折強度の１０％以下であることを特徴とする卑金属粉末。     Based on base metals,
    The average particle size is 5-30 nm,
    In the X-ray diffraction pattern, the strongest diffraction intensity of the main peak of the base metal hexagonal close-packed structure (hcp) and the main peak of the base metal oxide is the main peak of the base metal cubic close-packed structure (ccp). A base metal powder having a peak diffraction intensity of 10% or less.
  2. 　前記平均粒径が７～１０ｎｍであることを特徴とする請求項１に記載の卑金属粉末。 2. The base metal powder according to claim 1, wherein the average particle diameter is 7 to 10 nm.
  3. 　前記卑金属がニッケルまたは銅であることを特徴とする請求項１または２に記載の卑金属粉末。 The base metal powder according to claim 1 or 2, wherein the base metal is nickel or copper.
  4. 　（ａ）卑金属の硝酸塩と、オレイン酸ナトリウムまたはマレイン酸ナトリウムとを、水と、該水よりも極性の低い２種の溶媒との混合溶媒中に溶解して卑金属含有溶液を調製する工程と、
    （ｂ）該卑金属含有溶液から、前記卑金属を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る工程と、
    （ｃ）前記卑金属を含むオレイン酸の前駆体またはマレイン酸の前駆体を、還元雰囲気中にて、２５０～４００℃の温度で加熱する工程と、
    を具備することを特徴とする卑金属粉末の製法。     (A) a step of preparing a base metal-containing solution by dissolving a nitrate of a base metal and sodium oleate or sodium maleate in a mixed solvent of water and two kinds of solvents having a polarity lower than that of the water;
    (B) obtaining a precursor of oleic acid or maleic acid containing the base metal from the base metal-containing solution;
    (C) heating the precursor of oleic acid or maleic acid containing the base metal at a temperature of 250 to 400 ° C. in a reducing atmosphere;
    The manufacturing method of the base metal powder characterized by comprising.
  5. 　前記水よりも極性の低い２種の溶媒として、ヘキサンおよびエチルアルコールを用いることを特徴とする請求項４に記載の卑金属粉末の製法。 The method for producing a base metal powder according to claim 4, wherein hexane and ethyl alcohol are used as the two kinds of solvents having a polarity lower than that of water.
  6. 　前記卑金属の硝酸塩として、硝酸ニッケルまたは硝酸銅を用いることを特徴とする請求項４または５に記載の卑金属粉末の製法。 6. The process for producing a base metal powder according to claim 4, wherein nickel nitrate or copper nitrate is used as the nitrate of the base metal.
  7. 　請求項１～３のうちいずれかに記載の卑金属粉末と、有機ビヒクルとを含むことを特徴とする導体ペースト。 A conductor paste comprising the base metal powder according to any one of claims 1 to 3 and an organic vehicle.
  8. 　絶縁体と、該絶縁体の表面に設けられた導体膜とを具備し、前記導体膜が、前記絶縁体の表面に設けられた請求項７に記載の導体ペーストを焼成して形成されていることを特徴とする電子部品。 It comprises an insulator and a conductor film provided on the surface of the insulator, and the conductor film is formed by firing the conductor paste according to claim 7 provided on the surface of the insulator. An electronic component characterized by that.
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