JP2017182932A - Manufacturing method of metal powder paste, screen printing method of metal powder paste, manufacturing method of electrode, manufacturing method of tip laminate ceramic capacitor, and metal powder paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a manufacturing method of a metal powder paste suitably usable for manufacturing an internal electrode or the like of a tip laminate ceramic capacitor, excellent in vaporizability, resolvability, and coating performance, high in chemical stability and having sintering delay; a screen printing method of the metal powder paste; a manufacturing method of an electrode; a manufacturing method of the tip laminate ceramic capacitor; and the metal powder paste.SOLUTION: The manufacturing method of a metal powder paste includes: a surface treatment process for obtaining a metal powder (A1) to which one or more kind of metal of Si, Ti, Al, Zr, Ce, and Sn of 100 to 2000 μg based on 1 g of a metal powder (A), and N are adsorbed; and a paste preparation process for preparing a paste by dispersing the metal powder (A1) in a hydrocarbon compound (B) having kinetic viscosity at 40°C of 500 to 30000 mm/s.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a metal powder paste used for forming conductive circuits and electrodes provided on the surface, inside or outside of various substrates, a screen printing method for a metal powder paste, a method for producing an electrode, and a chip multilayer ceramic capacitor. The present invention relates to a method and a metal powder paste.

  The metal powder paste generally refers to a fluid in which metal powder is dispersed in a vehicle composed of an organic binder and a solvent. The metal powder paste is used, for example, for manufacturing a chip multilayer ceramic capacitor. Chip monolithic ceramic capacitors have a structure in which ceramic dielectrics and internal electrodes are stacked and integrated in layers, and each laminated layer constitutes a capacitor element, and these elements are electrically connected in parallel by external electrodes. Connected to become a small, large-capacity capacitor.

In the manufacture of a chip multilayer ceramic capacitor, a dielectric sheet is manufactured as follows. First, an organic binder and a solvent as a dispersing agent and a molding aid are added to a dielectric raw material powder such as BaTiO ₃ , and a slurry is obtained through pulverization, mixing, and defoaming steps. Thereafter, the slurry is thinly applied to a carrier film such as a PET film by a coating method such as a die coater. It is dried to obtain a thin dielectric sheet (green sheet).

  On the other hand, the metal powder that is a raw material of the internal electrode of the chip multilayer ceramic capacitor is mixed with an organic binder and a solvent as a dispersing agent and a molding aid, as in the case of the dielectric raw material powder, through a defoaming process, It is made into a metal powder paste. This is mainly printed on a green sheet (dielectric sheet) by screen printing to form an internal electrode. After drying, the printed green sheet is peeled off from the carrier film, and a large number of such green sheets are laminated. Let

  After the laminated green sheets are integrated by applying a press pressure of several tens to several hundreds of MPa, they are cut into individual chips. Thereafter, the internal electrode layer and the dielectric layer are sintered at a high temperature of about 1000 ° C. in a firing furnace to manufacture a chip multilayer ceramic capacitor.

  Various metals have been used for internal electrodes of chip multilayer ceramic capacitors from the viewpoint of cost and environmental regulations. Further, as the size of the capacitor is reduced, the internal electrode tends to be thinned, and it is desired that the particle size of the metal powder for the internal electrode be smaller.

  However, reducing the diameter of the metal powder lowers the melting point, starts melting at a lower temperature during sintering, and induces the generation of cracks in the electrode layer itself. In addition, since the electrode layer rapidly shrinks after the temperature is lowered, there is a possibility that the dielectric layer and the electrode layer are peeled off (delamination), and the metal powder for the internal electrode is required to have a heat shrinkage characteristic equivalent to that of the dielectric. . As an index representing this, there is a sintering start temperature.

  In response to such a demand, in order to obtain a metal powder suitable for the internal electrode of the chip multilayer ceramic capacitor by adding dielectric particles or glass frit to the metal powder paste to reduce the contact between the metal powders, or A method for performing surface treatment on metal powder has been proposed.

  In the technique of adding dielectric particles or glass frit to the metal powder paste, if it is not smaller than the metal powder, these become resistance in the sintered conductor layer, and the function as an electrode is lowered. For this reason, dielectric particles and glass frit must be smaller than metal powder. When the metal powder itself is 0.1 μm, the dielectric particles and the glass frit need to be several tens of nm in size. For this reason, handling becomes difficult and the raw material cost of the paste becomes high.

On the other hand, as a technique for performing surface treatment on metal powder, a technique for forming an SiO ₂ gel coating film by subjecting alkoxysilane hydrolyzed on the surface of copper powder to condensation polymerization with an ammonia catalyst (see, for example, Patent Document 1), a specific method Technology for coating copper powder with silicone oil having functional groups (see, for example, Patent Document 2), covering nickel powder with nickel complex ions with a silane coupling agent having amino groups, and further heat-treating the silica layer The technique (for example, refer patent documents 3-7) and the technique (for example, refer patent documents 4-7) which surface-treat copper powder with the silane coupling agent which has an amino group (for example, refer patent document 3) are disclosed.

Japanese Patent No. 3646259 Japanese Patent No. 4164209 Japanese Patent No. 4588688 JP 2013-171745 A International Publication No. 2013/125659 JP2015-36445A JP-A-2015-36439

  According to the above-mentioned patent document, the oxidation resistance can be improved and the sintering start temperature can be set to a desired range by surface-treating the metal powder. When such metal powder is dispersed in a solvent together with an organic binder to form a metal powder paste, and coated on a green sheet and sintered, a carbonaceous component that is a decomposition product such as an organic binder remains, The sinterability of the metal powder may be impaired. In order to solve this problem, there is a debinding process in which oxygen is mixed into the inert gas atmosphere to burn and remove carbonaceous components derived from organic binders, etc., or metal powder oxidized after the debinding process is reduced. Although a reduction process for reducing in a gas atmosphere is provided, it has been pointed out that the process becomes longer and that the final product may be adversely affected by the oxidation and reduction of metal powder.

  The present invention has been made in view of the above, and can be suitably used for the production of internal electrodes and the like of chip multilayer ceramic capacitors, and is excellent in evaporability and decomposability, so there is no need to provide a debinding step. To provide a metal powder paste manufacturing method, a metal powder paste screen printing method, an electrode manufacturing method, a chip multilayer ceramic capacitor manufacturing method, and a metal powder paste that are excellent in coating properties and have a sintering delay. It is in.

  As a result of intensive studies, the present inventors have solved the above problem by dispersing a metal powder adsorbing a predetermined amount of element by surface treatment in a hydrocarbon compound having a predetermined kinematic viscosity to obtain a metal powder paste. The present inventors have found that this can be done and have completed the present invention.

The manufacturing method of the metal-powder paste concerning this invention is 100-2000 micrograms in any one metal among Si, Ti, Al, Zr, Ce, and Sn with respect to 1g of metal powder (A), and N. A paste is prepared by dispersing a surface treatment step for obtaining an adsorbed metal powder (A1) and the metal powder (A1) in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s. And a paste preparation step.

  Moreover, the method for producing a metal powder paste according to the present invention is characterized in that, in the above invention, the surface treatment step adsorbs N to 0.02% by mass or more with respect to the metal powder (A1). To do.

Moreover, the method for producing a metal powder paste according to the present invention is characterized in that, in the above-mentioned invention, the hydrocarbon compound (B) has a kinematic viscosity at 40 ° C. of 500 to 10,000 mm ² / s.

  Moreover, the manufacturing method of the metal powder paste concerning this invention is the said invention, The said hydrocarbon compound (B) contains polybutene (B1), It is characterized by the above-mentioned.

  Moreover, the screen printing method of the metal powder paste according to the present invention includes a filtration step of filtering the metal powder paste produced by the method for producing a metal powder paste according to any one of the above, and the filtration. And a printing step of screen-printing the metal powder paste filtered in the step on a green sheet.

  Moreover, the manufacturing method of the electrode concerning this invention is an application process which apply | coats the said metal powder paste manufactured by the manufacturing method of any one of said metal powder paste to a base material, and the said application | coating process. And a sintering step of heating and sintering the metal powder paste applied to the substrate to form an electrode.

  The electrode manufacturing method according to the present invention is characterized in that, in the above invention, the sintering step heats and sinters the metal powder paste to form an electrode having a metallic luster.

  Moreover, the manufacturing method of the chip multilayer ceramic capacitor according to the present invention includes an application step of applying the metal powder paste manufactured by the metal powder paste manufacturing method according to any one of the above to a base material, After laminating the base material coated with the metal powder paste and integrating by applying pressure, it comprises a singulation step for dividing into chips, and a sintering step for heating and sintering the chips. It is characterized by that.

Further, in the metal powder paste according to the present invention, 100 to 2000 μg of any one or more metals of Si, Ti, Al, Zr, Ce, and Sn are adsorbed to 1 g of the metal powder (A) and N. In addition, a surface-treated metal powder (A1) having a D50 of 0.5 μm or less and a Dmax of 1.0 μm or less is dispersed in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s. Thus, the metal powder (A1) is characterized in that N is adsorbed by 0.02% by mass or more.

  In the metal powder paste according to the present invention, the sintering start temperature of the metal powder (A1) is 350 ° C. or higher.

  The metal powder paste according to the present invention is excellent in coating properties without the addition of an organic binder and can flatten the coating film of the metal powder paste. Moreover, since no organic binder is blended, there is no need to perform a debinding step and a subsequent reduction step. In addition, the hydrocarbon compounds used have high evaporability, decomposability and chemical stability, and the metal powder paste has excellent sintering delay and metal powder dispersibility. In this case, it is excellent in workability and productivity, avoiding manufacturing problems such as electrode peeling, and can advantageously manufacture a chip multilayer ceramic capacitor electrode or the like to be thinned.

FIG. 1 is an SEM image of the sintered body according to Example 2. As shown in FIG. FIG. 2 is a view showing an SEM image of a sintered body according to Comparative Example 1.

  The metal powder paste production method, metal powder paste screen printing method, electrode production method, chip multilayer ceramic capacitor production method and metal powder paste preferred embodiment according to the present invention will be described in more detail below. The description of the constituent requirements described in the above is an example of embodiments of the present invention, and the present invention is not limited to these contents, and various modifications can be made within the scope of the gist.

In the metal powder paste according to the present invention, 100 to 2000 μg of any one or more metals among Si, Ti, Al, Zr, Ce, and Sn are adsorbed on 1 g of the metal powder (A), and N is adsorbed. A surface-treated metal powder (A1) having a D50 of 0.5 μm or less and a Dmax of 1.0 μm or less is dispersed in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s. It is characterized by becoming.

<Metal powder (A)>
First, the metal powder (A) will be described. As the metal of the metal powder (A) used in the present invention, for example, a metal selected from Ag, Pd, Pt, Ni and Cu can be used, and preferably selected from Ag, Ni and Cu. Used metal can be used. As the metal powder (A), copper powder, silver powder, and nickel powder are preferable.
As the metal powder (A), a metal powder (A) produced by a known method can be used. In a preferred embodiment, for example, a metal powder (A) produced by a wet method or a metal powder (A) produced by a dry method can be used. In a preferred embodiment, copper powder produced by a wet method, for example, copper powder produced by a disproportionation method, a chemical reduction method, or the like can be used. The copper powder produced by the wet method is suitable in that it is a wet process consistently with the surface treatment according to the present invention.

<Manufacture of copper powder by wet method>
In a preferred embodiment, as a method of producing copper powder by a wet method, a step of preparing a slurry by adding cuprous oxide in an aqueous solvent containing an additive of gum arabic, and dilute sulfuric acid in the slurry within 5 seconds The copper powder manufactured by the method including the process of adding at once and performing a disproportionation reaction can be used. In a preferred embodiment, the slurry can be kept at room temperature (20 to 25 ° C.) or lower, and dilute sulfuric acid kept at room temperature or lower can be added to perform a disproportionation reaction. In a preferred embodiment, the slurry can be maintained at 7 ° C. or lower, and dilute sulfuric acid maintained at 7 ° C. or lower can be added to perform a disproportionation reaction. In a preferred embodiment, dilute sulfuric acid can be added so that the pH is 2.5 or less, preferably pH 2.0 or less, and more preferably pH 1.5 or less. In a preferred embodiment, the addition of dilute sulfuric acid to the slurry is within 5 minutes, preferably within 1 minute, more preferably within 30 seconds, more preferably within 10 seconds, more preferably within 5 seconds. , Can be added. In a preferred embodiment, the disproportionation reaction can be completed in 10 minutes. In a preferred embodiment, the concentration of gum arabic in the slurry can be 0.229 to 1.143 g / L. As the cuprous oxide, it is possible to use cuprous oxide used in a known method, preferably cuprous oxide particles, and the particle size of the cuprous oxide particles is a copper powder produced by a disproportionation reaction. Since it is not directly related to the particle size of the particles, coarse cuprous oxide particles can be used. The principle of this disproportionation reaction is as follows.
Cu ₂ O + H ₂ SO ₄ → Cu ↓ + CuSO ₄ + H ₂ O
The copper powder obtained by this disproportionation can be washed, rust-prevented, filtered, dried, crushed and classified, if desired, and then mixed with an aqueous solution of a coupling agent having an amino group. In a preferred embodiment, after washing, rust prevention and filtration, it can be directly mixed with an aqueous solution of a coupling agent having an amino group without drying.

The copper powder obtained by the disproportionation reaction has an average particle size (D50) measured by a laser diffraction particle size distribution measuring device of 0.25 μm or less. In a preferred embodiment, the copper powder obtained by the disproportionation reaction has a D10, D90, and Dmax measured by a laser diffraction particle size distribution measuring apparatus satisfying the following formula and having a single particle size distribution: Has a peak.
[Dmax ≦ D50 × 3, D90 ≦ D50 × 2, D10 ≧ D50 × 0.5]
In a preferred embodiment, the copper powder obtained by the disproportionation reaction has a single particle size distribution (having a single peak) as measured by a laser diffraction particle size distribution analyzer. In a preferred embodiment, the value measured by a laser diffraction particle size distribution analyzer is [D50 ≦ 1.5 μm], preferably [D50 ≦ 1.0 μm], and more preferably [D50 ≦ 0. 5 μm, Dmax ≦ 1.0 μm]. As a laser diffraction type particle size distribution measuring device, for example, SALD-2100 manufactured by Shimadzu Corporation can be used.

<Silver powder>
When using silver powder as metal powder (A), silver powder can be manufactured according to Unexamined-Japanese-Patent No. 2007-291513. For example, 12.6 g of silver nitrate is dissolved in 0.8 L of pure water, 24 mL of 25% aqueous ammonia and 40 g of ammonium nitrate are added to prepare a silver ammine complex salt aqueous solution. 1 g / L of gelatin was added thereto, and this was used as an electrolyte solution. Electrodeposited silver particles were electrolyzed at a current density of 200 A / m ² and a solution temperature of 20 ° C. using a DSE plate for both the anode and cathode. Was electrolyzed for 1 hour while scraping off the electrode plate. The silver powder thus obtained may be filtered with Nutsche and washed in the order of pure water and alcohol. The obtained silver powder has the following characteristics. The measurement used the laser diffraction type particle size distribution measuring apparatus (SALD-2100 made by Shimadzu Corporation).
D50: 0.10 μm, Dmax: 0.50 μm, distribution: one mountain

<Nickel powder>
When nickel powder is used as the metal powder (A), nickel powder can be produced according to JP 2010-59467 A. For example, after gelatin is dissolved in 6 L of pure water, hydrazine is mixed so that the concentration becomes 0.02 g / L, and a mixed solution of palladium and a small amount of silver is dropped to form a colloidal solution. The pH is adjusted to 10 or more by addition, and hydrazine is further added until the hydrazine concentration becomes 26 g / L.
On the other hand, chromium chloride and magnesium chloride are added to a nickel chloride aqueous solution having a nickel concentration of 100 g / L so that the concentrations of chromium and magnesium with respect to nickel are 0.03% by mass. To this, 0.5 L of the hydrazine solution is dropped and nickel is deposited by reduction to obtain nickel powder. The obtained nickel powder has the following characteristics. The measurement used the laser diffraction type particle size distribution measuring apparatus (SALD-2100 made by Shimadzu Corporation).
D50: 0.17 μm, Dmax: 0.51 μm, distribution: one mountain

<Elements adsorbed on metal powder (A)>
One or more elements selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn are adsorbed on the surface of the metal powder (A) by the surface treatment to form a surface treatment layer. . In a preferred embodiment, the element thus adsorbed by the surface treatment is one element selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn, preferably Al, Si, and One element selected from the group consisting of Ti, more preferably Si or Ti. In addition to the above elements, N adsorbs to the metal powder (A).

<Coupling agent (C) having an amino group forming the surface treatment layer>
The surface-treated metal powder (A1) in the present invention has a surface treatment layer containing N and at least one element selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn. Yes, these elements are derived from the coupling agent (C) having an amino group. In a preferred embodiment, examples of the coupling agent (C) having an amino group may include one or more coupling agents selected from the group consisting of aminosilane, amino-containing titanate, and amino-containing aluminate. . In a preferred embodiment, the coupling agent (C) having an amino group has a structure having an amino group at the end of a molecular chain coordinated with Al, Ti, or Si as a central atom. The present inventor believes that the amino group positioned at this end brings about a suitable surface treatment.

<Aminosilane>
In a preferred embodiment of the present invention, the coupling agent (C) having an amino group is represented by the following formula I:
H ₂ N—R ¹ —Si (OR ² ) ₂ (R ³ ) (Formula I)
(In the above formula I, R ¹ is linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, having a heterocyclic ring or having a heterocyclic ring. no, a divalent radical of a hydrocarbon of Cl -C 12, ^{R 2} is an alkyl group of C1 to C5, ^{R 3} is an alkyl group, or an alkoxy group of C1 to C5 of C1 to C5.)
The aminosilane represented by these can be used.

In the above formula I, R ¹ is linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, having a heterocyclic ring or not having a heterocyclic ring, C1 -C12 hydrocarbon divalent group, preferably R ¹ is a substituted or unsubstituted C1-C12 linear saturated hydrocarbon divalent group, substituted or unsubstituted C1-C12 Branched saturated hydrocarbon divalent group, substituted or unsubstituted, C1-C12 linear unsaturated hydrocarbon divalent group, substituted or unsubstituted C1-C12 branched unsaturated hydrocarbon A divalent group of a substituted or unsubstituted C1-C12 cyclic hydrocarbon, a substituted or unsubstituted C1-C12 heterocyclic hydrocarbon divalent group, a substituted or unsubstituted, It can be a group selected from the group consisting of C1-C12 aromatic hydrocarbon divalent groups. In a preferred embodiment, R ¹ is a C1-C12 saturated or unsaturated chain hydrocarbon divalent group, and more preferably two atoms having free valences at both ends of the chain structure. It is a valent group. In a preferred embodiment, the carbon number of the divalent group can be, for example, C1 to C12, preferably C1 to C8, preferably C1 to C6, preferably C1 to C3.

In a preferred embodiment, R ¹ represents — (CH ₂ ) _n —, — (CH ₂ ) _m — (CH═CH) — (CH ₂ ) _j —, — (CH ₂ ) _m — (C≡C). _{- (CH 2) j -,} - (CH 2) m + 1 -NH- (CH 2) j + 1 -, - (CH 2) s -NH- (CH 2) t + 1 -NH- (CH 2) u -, - ( _{CH 2) m - (CH)} NH 2 - (CH 2) j + 1 -, - (CH 2) s - (CH) NH 2 - (CH 2) t -NH- (CH 2) u -, - CO-NH — (CH ₂ ) _n —, —CO—NH— (CH ₂ ) _{m + 1} —NH— (CH ₂ ) _{j + 1} — is a group selected from the group consisting of n (where n is an integer of 1-12), m , J is an integer greater than or equal to 1 and m + j ≦ 10, s, t, u are integers greater than or equal to 1, s t + a u ≦ 11. Moreover, the (CH = CH) represents a double bond between C and C, the (C [identical to] C) represents the triple bond of the C and C). In a preferred embodiment, R ¹ can be — (CH ₂ ) _n —, or — (CH ₂ ) _{m + 1} —NH— (CH ₂ ) _{j + 1} —. In a preferred embodiment, the hydrogen of R ¹ as the above divalent group may be substituted with an amino group, for example 1 to 3 hydrogens, for example 1 to 2 hydrogens, for example 1 hydrogen. May be substituted by an amino group.

  In a preferred embodiment, n is preferably an integer of 1 to 6, more preferably an integer of 1 to 4, for example, an integer selected from 1, 2, 3, 4 For example, it can be 1, 2 or 3. M and j are integers of 1 or more, preferably m + j ≦ 8, and more preferably m + j ≦ 6. s, t, u are integers of 1 or more, preferably s + t + u ≦ 8, and more preferably s + t + u ≦ 6.

In the above formula I, R ² can be a C1-C5 alkyl group, preferably a C1-C3 alkyl group, more preferably a C1-C2 alkyl group, for example, a methyl group, an ethyl group, an isopropyl group. Or a propyl group, and more preferably a methyl group or an ethyl group.

In the above formula I, R ³ can be a C1-C5 alkyl group, preferably a C1-C3 alkyl group, more preferably a C1-C2 alkyl group, for example, a methyl group, an ethyl group, an isopropyl group. Or a propyl group, and more preferably a methyl group or an ethyl group. R ³ may be a C1-C5 alkoxy group, preferably a C1-C3 alkoxy group, more preferably a C1-C2 alkoxy group as an alkoxy group. For example, methoxy group, ethoxy group, It can be a propoxy group or a propoxy group, more preferably a methoxy group or an ethoxy group.

<Amino group-containing titanate>
In a preferred embodiment, the coupling agent having an amino group has the following formula II:
(H ₂ N—R ¹ —O) _p Ti (OR ² ) _q (Formula II)
(However, in the above formula II,
R ¹ is linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic, C1-C12 hydrocarbon A divalent group of
R ² is a linear or branched C1-C5 alkyl group,
p and q are integers of 1 to 3, and p + q = 4. )
An amino group-containing titanate represented by the formula can be used.

In a preferred embodiment, as R ¹ of the above formula II, the groups exemplified as R ¹ of the above formula I can be preferably used. As ^{R 1} in the formula II, for _{example, - (CH 2) n -} , - (CH 2) m - (CH = CH) - (CH 2) j -, - (CH 2) m - (C≡C) _{- (CH 2) j -,} - (CH 2) m + 1 -NH- (CH 2) j + 1 -, - (CH 2) s -NH- (CH 2) t + 1 -NH- (CH 2) u -, - ( _{CH 2) m - (CH)} NH 2 - (CH 2) j + 1 -, - (CH 2) s - (CH) NH 2 - (CH 2) t -NH- (CH 2) u -, - CO-NH — (CH ₂ ) _n —, —CO—NH— (CH ₂ ) _{m + 1} —NH— (CH ₂ ) _{j + 1} — is a group selected from the group consisting of n (where n is an integer of 1-12), m , J is an integer greater than or equal to 1 and m + j ≦ 10, s, t, u are integers greater than or equal to 1, s + t A u ≦ 11. Moreover, the (CH = CH) represents a double bond between C and C, the (C [identical to] C) represents the triple bond of the C and C). As particularly suitable R ¹ , — (CH ₂ ) _{m + 1} —NH— (CH ₂ ) _{j + 1} — can be mentioned (where m + j = 4, particularly preferably m = j = 2).

In the formula II, R ² may be preferably used a group exemplified as R ² in formula I. In a preferred embodiment, a C3 alkyl group can be exemplified, and particularly preferably, a propyl group and an isopropyl group can be exemplified.

  In the above formula II, p and q are integers of 1 to 3, and p + q = 4, preferably a combination of p = q = 2, a combination of p = 3 and q = 1. As an amino group-containing titanate in which a functional group is arranged in this way, plain act KR44 (manufactured by Ajinomoto Fine Techno Co., Ltd.) can be exemplified.

<Formation of surface treatment layer>
A metal powder dispersion is prepared by mixing the metal powder (A) with an aqueous solution of a coupling agent (C) having an amino group. In a preferred embodiment, the metal powder dispersion is 0.005 g or more, 0.025 g or more, preferably 0.050 g or more of the coupling agent (C) having an amino group with respect to 1 g of the metal powder (A). More preferably, it may be 0.075 g or more, and more preferably 0.10 g or more. From the viewpoint of adjusting the amount of adsorption of one or more elements selected from the group consisting of Si, Ti, Al, Zr, Ce and Sn to the metal powder (A), an amino group is added to 1 g of the metal powder (A). The coupling agent (C) having a ratio of 0.005 g to 0.500 g, preferably 0.025 g to 0.250 g, and more preferably 0.025 g to 0.100 g. . The metal powder (A) and the aqueous solution of the coupling agent (C) having an amino group can be mixed by a known method. In this mixing, stirring can be appropriately performed by a known method. In a preferred embodiment, the mixing can be performed, for example, at room temperature, for example, at a temperature in the range of 5-80 ° C, 10-40 ° C, 20-30 ° C.

  In a preferred embodiment, a step of stirring the metal powder dispersion can be performed after the step of preparing the metal powder dispersion. In a preferred embodiment, a step of ultrasonicating the metal powder dispersion can be performed after the step of preparing the metal powder dispersion. This stirring and sonication can be performed only in either one, but both can be performed simultaneously or before and after. The ultrasonic treatment can be performed at an output of preferably 50 W to 600 W, more preferably 100 W to 600 W per 100 ml of the metal powder dispersion. In a preferred embodiment, the sonication can be performed at a frequency of preferably 10 MHz to 1 MHz, more preferably 20 MHz to 1 MHz, more preferably 50 MHz to 1 MHz. The treatment time of the ultrasonic treatment is selected according to the state of the metal powder dispersion, but is preferably 1 minute to 180 minutes, more preferably 3 minutes to 150 minutes, further preferably 10 minutes to 120 minutes, more preferably. It can be 20 minutes to 80 minutes.

  After the metal powder (A) in the metal powder dispersion is sufficiently in contact with the coupling agent (C) by mixing, stirring and / or sonication, the metal powder dispersion is separated from the metal powder ( The step of recovering A ′) as a residue and the step of washing the metal powder (A ′) recovered as a residue with an aqueous solvent are performed. Recovery as a residue can be performed by a known means. For example, filtration, decantation, centrifugation, or the like can be used, and filtration can be preferably used. Washing with an aqueous solvent can be performed by a known means using an aqueous solvent. For example, it can be carried out by adding an aqueous solvent to the residue and stirring and then collecting it again as a residue, or, for example, by continuously adding an aqueous solvent to the residue placed on the filtration filter Can also be done.

  In a preferred embodiment, washing with an aqueous solvent is carried out by ICP analysis in the filtrate obtained after adding 5 times the mass of the aqueous solvent to the dry mass of the metal powder (A ′) after washing. Metal powder recovered as a residue until at least one element selected from the group consisting of Si, Ti, Al, Zr, Ce and Sn to be detected has a concentration of 50 ppm or less, preferably 30 ppm or less. This can be done by washing (A ′) with an aqueous solvent. Although there is no restriction | limiting in particular in the minimum of the said density | concentration, For example, it can be 1 ppm or more, for example, 5 ppm or more.

  As an aqueous solvent used for washing, pure water or an aqueous solution can be used. Examples of the aqueous solution include an aqueous solution in which one or more solutes or solvents selected from inorganic acids, inorganic acid salts, organic acids, organic acid salts, water-soluble alcohols, and water-soluble esters are dissolved or dispersed. Can be used. Examples of inorganic acids and salts thereof include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and carbonic acid, and salts thereof. Examples of the salt include sodium salt, potassium salt, and calcium salt. Examples of organic acids and salts thereof include 1 to 3 valent C1 to C7 carboxylic acids and salts thereof, such as formic acid, acetic acid, lactic acid, malic acid, citric acid, oxalic acid, benzoic acid, And phthalic acid and their salts. Examples of the salt include sodium salt, potassium salt, and calcium salt. Examples of water-soluble alcohols include 1 to 3 valent C1 to C6 alcohols, and examples include methanol, ethanol, isopropyl alcohol, ethylene glycol, glycerin, and phenol. Examples of the water-soluble ester include C1 to C12 esters, and examples thereof include the above-described esters of an acid and an alcohol. The pH of the aqueous solvent is preferably pH 7 to 14, more preferably pH 8 to 12. As pure water, highly purified high-purity water can be used, but water that is industrially pure and has no intentional addition of compounds, Can be used. The content of the solute dissolved in the aqueous solution is a content in a range where the solute can be dissolved, and a content that can make the concentration of the element detected by the ICP analysis described above within the above range. Can be used. Within the range satisfying such conditions, the solute can be contained, for example, in the range of 0.0001% by mass to 20% by mass and 0.001% by mass to 10% by mass with respect to the mass of the aqueous solution.

  The washed metal powder (A ′) can be separated from the aqueous solvent and proceed to the next step without being dried if desired, but is dried as desired to obtain the surface-treated metal powder (A1). You can also. A known means can be used for this drying. In a preferred embodiment, this drying can be performed in an oxygen atmosphere or an inert atmosphere. Drying can be performed by heating, for example, and can be performed at a temperature of 50 to 90 ° C. or 60 to 80 ° C., for example, by a heat treatment for 30 to 120 minutes or 45 to 90 minutes. Following the heat drying, if necessary, the surface-treated metal powder (A1) may be further pulverized.

  In a preferred embodiment, the recovered surface-treated metal powder (A1) may be subjected to further surface treatment as a post-treatment. For the purpose of preventing rust or improving dispersibility in the paste, an organic substance or the like may be further adsorbed on the surface of the surface-treated metal powder (A1). As such a surface treatment, for example, an antirust treatment with an organic antirust agent such as benzotriazole or imidazole can be given, and even with such a normal treatment, the surface with a coupling agent (C) having an amino group The treatment layer is not detached. Those skilled in the art can perform such known surface treatments as desired within the limits that do not lose the excellent sintering retardancy. To the surface of the surface-treated metal powder (A1), the metal powder (A2) obtained by further surface treatment within the limit that does not lose the excellent sintering delay property, that is, 1 g of the metal powder (A) On the other hand, the metal powder (A2) in which at least one metal of Si, Ti, Al, Zr, Ce, and Sn is adsorbed in an amount of 100 to 2000 μg and N is within the scope of the present invention.

<Sintering start temperature of metal powder (A1)>
The surface-treated metal powder (A1) is dispersed in a hydrocarbon compound (B) described later to form a conductive metal powder paste, and an electrode can be manufactured by sintering this. The surface-treated metal powder (A1) according to the present invention has an excellent sintering delay. As an index of the sintering delay property, there is a sintering start temperature. This is the temperature at which a certain volume change (shrinkage) occurs when the green compact made of the metal powder (A1) is heated in a reducing atmosphere. In the present invention, the temperature at which 1% volume shrinkage occurs is the sintering start temperature. It means that the higher the sintering start temperature of the metal powder (A1), the better the metal powder paste has a sintering delay property.

The sintering start temperature of the metal powder (A1) can be measured using a TMA (Thermomechanical Analyzer) by preparing a sample of the surface-treated metal powder (A1). For example, a predetermined amount of zinc stearate is added to and mixed with metal powder (A1), this mixture is loaded into a cylinder having a diameter of 7 mm, a punch is pushed in from the top, and held at 1 Ton / cm ² for 3 seconds, A cylindrical shaped sample corresponding to a height of about 5 mm is prepared. This molded body sample was loaded into a heating furnace under the condition that the axis was set in the vertical direction and a load of 98.0 mN was applied in the axial direction, and the sample was raised in a flow rate of ₂ vol% H ₂ -N ₂ (300 cc / min). The temperature is continuously increased to a temperature rate of 5 ° C./minute and a measurement range: 50 to 1000 ° C., and the height change (expansion / shrinkage change) of the molded body is automatically recorded. The temperature at which the height change (shrinkage) of the molded body sample starts and the shrinkage rate reaches 1% is defined as “sintering start temperature”.

  In a preferred embodiment, the sintering start temperature of the surface-treated metal powder (A1) according to the present invention is 450 ° C. or higher, preferably 500 ° C. or higher, more preferably 600 ° C. or higher, more preferably 700 ° C. or higher. More preferably 780 ° C. or higher, more preferably 800 ° C. or higher, more preferably 810 ° C. or higher, more preferably 840 ° C. or higher, more preferably 900 ° C. or higher, more preferably 920 ° C. or higher, more preferably 950 ° C. or higher. can do. In particular, the sintering start temperature of Ni ultrafine powder (average particle size of 0.2 μm to 0.4 μm) that has been conventionally used when a high sintering start temperature is required is in the range of 500 ° C. to 600 ° C. Compared with, the surface-treated copper powder according to the present invention uses Cu, which is cheaper and easier to obtain than Ni, and has fine particles, but has superior or better sintering delay. Yes. Moreover, the nickel powder which performed the surface treatment concerning this invention also has the sintering delay property outstanding from the past.

<Thickness of surface treatment layer of metal powder (A1)>
In a preferred embodiment of the present invention, the thickness x (nm) of the surface treatment layer formed by adsorbing one or more elements selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn is: It can be determined by a concentration profile of EDS (Energy Dispersive X-ray Spectroscopy) near the surface obtained by STEM (Scanning Transmission Electron Microscope). The thickness of the surface treatment layer, for example, when Si is included as an element, the thickness of the Si-containing layer (Si thickness) is measured by EDS in the cross section of the surface of the surface-treated metal powder, When the abundance of Si atoms at a depth where the abundance ratio of atoms is maximum is 100%, the abundance of Si atoms is defined as being in a range of 10% or more. The cross section of the surface of the surface-treated metal powder (A1) is selected from among at least 100 or more metal powder (A1) particles observed in the sample section, and the most clear boundary is selected on the surface. Measurement and counting can be performed by treating the cross section as being perpendicular to the surface of the treated metal powder (A1). The thickness of the surface treatment layer can be obtained in the same manner as the thickness of the Si-containing layer (Si thickness) even in the case of the thickness of the Ti-containing layer (Ti thickness), the thickness of the Al-containing layer (Al thickness), or the like.

In a preferred embodiment, the surface-treated metal powder (A1) is a surface containing one or more elements selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn measured by the above method. It is preferable that the thickness x (nm) of the treatment layer and the sintering start temperature y (° C.) of the metal powder (A1) satisfy the following formula.
0.5 ≦ x ≦ 10, 25x + 620 ≦ y
When the thickness x of the surface treatment layer is smaller than 0.5 nm, the sintering delay effect of the metal powder (A1) is small, and when it is larger than 10 nm, the metal powder (A1) is likely to aggregate.

<Amount of elements adsorbed on metal powder (A1)>
The surface-treated metal powder (A1) contains 100 to 2000 μg of one or more elements selected from the group consisting of Al, Si, Ti, Zr, Ce, and Sn with respect to 1 g of the metal powder (A). Adsorbed. By setting the adsorption amount of the element to 1 g of the metal powder (A) within the above range, a metal powder paste having excellent sintering delay and dispersibility can be obtained. The amount of the element adsorbed on 1 g of the metal powder (A) is preferably 100 to 600 μg. The amount of adsorbed element was surface-treated by dissolving the surface-treated metal powder (A1) with an acid and quantifying it with ICP-AAS (Inductively Coupled Plasma-Atomic Absorption Spectrometry). It can obtain | require from the mass (microgram) of the adsorbed element with respect to the unit mass (g) of metal powder (A1).

In a preferred embodiment, the surface-treated metal powder (A1) has an adsorption amount of 1 element selected from the group consisting of Al, Si, Ti, Zr, Ce and Sn to 1 g of the metal powder. μg), and when the sintering start temperature is y (° C.), it is preferable to satisfy the following formula.
100 ≦ z ≦ 2000, y ≧ 0.2z + 600
When the adsorption amount z of the element is smaller than 100 μg, the sintering delay effect of the metal powder (A1) is reduced, and when it is larger than 2000 μg, the metal powder (A1) is likely to aggregate.

The metal powder (A1) contains N (nitrogen) derived from the amino group at the terminal of the coupling agent (C) having an amino group used when forming the surface treatment layer. In a preferred embodiment, the ratio of N (nitrogen) to the surface-treated metal powder (A1) can be preferably 0.02% by mass or more, more preferably 0.03% by mass or more, and the upper limit. Is preferably 0.50% by mass, more preferably 0.20% by mass, and still more preferably 0.15% by mass. By setting the amount of N adsorbed on the metal powder (A1) within the above range, a metal powder paste having excellent workability without aggregation of the metal powder (A1) can be obtained. The mass% of N (nitrogen) adsorbed on the surface-treated metal powder (A1) can be calculated from NO ₂ generated by melting the metal powder (A1) at a high temperature.

<Particle size of metal powder (A1)>
The surface-treated metal powder (A1) can have an average particle diameter D50 measured by a laser diffraction particle size distribution analyzer of 0.05 to 1 μm, preferably 0.05 to 0.5 μm. The maximum particle diameter Dmax is 1.0 μm or less, and no secondary particles can be present. As a laser diffraction type particle size distribution measuring device, for example, SALD-2100 manufactured by Shimadzu Corporation can be used. In the present invention, secondary particles refer to particles in the vicinity of a large maximum value side when there are a plurality of maximum values when the particle size distribution is measured by the above method. When the maximum value of the particle size distribution is only one in the above method, secondary particles are not present.

<Manufacture of metal powder paste>
The surface-treated metal powder (A1) is dispersed in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s to produce a metal powder paste.

<Hydrocarbon compound (B)>
The hydrocarbon compound (B) is not particularly limited as long as the kinematic viscosity at 40 ° C. is 500 to 30000 mm ² / s. The hydrocarbon compound (B) may be a single compound, but is usually a mixture of a plurality of hydrocarbons, and preferably used if the mixture has a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s. Is possible. If the kinematic viscosity at 40 ° C. of the hydrocarbon compound (B) is smaller than 500 mm ² / s, the coating film may be cut off when the metal powder paste is applied to the substrate. Further, if the kinematic viscosity at 40 ° C. of the hydrocarbon compound (B) is larger than 30000 mm ² / s, the viscosity of the metal powder paste becomes too large, so that it is difficult to print a wiring pattern with a narrow pitch and difficult to downsize. It becomes. The kinematic viscosity of 40 ° C. hydrocarbon compound (B) is preferably from 500~20000mm ² / s, more preferably 500~10000mm ² / s.

  The kinematic viscosity at 40 ° C. of the hydrocarbon compound (B) was measured according to JIS K2283 “Crude oil and petroleum products—Kinematic viscosity test method and viscosity index calculation method”.

  The hydrocarbon compound (B) preferably contains polybutene (B1). Polybutene is a polymer mainly composed of repeating units of isobutene, in addition to a polymer consisting of only repeating units of isobutene, in addition to isobutene repeating units, butene isomers other than isobutene such as butene-1, and the like. Polymers containing butadiene repeating units may also be included.

  The proportion of isobutene repeating units in the polybutene (B1) is preferably 60 mol% or more, and more preferably 80 mol% or more.

  In a preferred embodiment, the proportion of polybutene (B1) contained in the hydrocarbon compound (B) is preferably in the range of 80 to 100% by mass.

  In a preferred embodiment, the number average molecular weight of the polybutene (B1) may be in the range of 500-1500.

  The number average molecular weight of polybutene (B1) can be measured by gel permeation chromatography (GPC).

  The chlorine content of polybutene (B1) is preferably a low chlorine concentration from the viewpoint of the stability of the metal powder paste. The chlorine concentration is preferably 100 ppm or less, and particularly preferably 10 ppm or less.

  The chlorine of polybutene (B1) can be measured by a combustion ion chromatograph.

<Solvent (D)>
In a preferred embodiment of the present invention, the metal powder paste is used for screen printing of electronic materials in addition to the metal powder (A1) and the hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s or more. The solvent (D) used for the paste may be included. As the solvent (D), a solvent used in a paste for screen printing of electronic materials can be used. Examples of such a solvent include an alcohol solvent, a glycol ether solvent, an acetate solvent, and a ketone solvent. Can do. Examples of the alcohol solvent include terpineol, isopropyl alcohol, and butyl carbitol. Examples of terpineol include α-terpineol, β-terpineol, and γ-terpineol, and α-terpineol is particularly preferable. Examples of the glycol ether solvent include butyl carbitol. Examples of the acetate solvent include butyl carbitol acetate. Examples of the ketone solvent include methyl ethyl ketone. In addition, the solvent (D) was added to the hydrocarbon compound (B) whose kinematic viscosity of 40 degreeC is 500-30000 mm < ² > / s or more from a viewpoint of maintaining the coating-film performance at the time of apply | coating a metal powder paste to a base material. It is preferable to add the mixture so that the kinematic viscosity at 40 ° C. does not become smaller than 500 mm ² / s.

<Preparation of metal powder paste>
When the surface-treated metal powder (A1) is a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s or more, or a solvent (D), the hydrocarbon compound (B) and the solvent The operation of preparing the metal powder paste by dispersing in the mixture of (D) can be performed by a known dispersing means, and if desired, stirring, kneading, and ultrasonic treatment may be performed.

<Filter filtration of metal powder paste>
In a preferred embodiment of the present invention, it is preferable to perform a step of filtering the prepared metal powder paste with a filter after preparing the metal powder paste. Filtration with such a filter is performed in order to form a fine wiring or an extremely thin conductive layer (electrode) with a metal powder paste. In a preferred embodiment, for example, a filter having a pore size of 1-8 μm, preferably 1-5 μm can be used. In a preferred embodiment, filtration through a filter is performed by vacuum filtration or pressure filtration. The pressure when performing vacuum filtration can be, for example, in the range of 0.1 to 1.0 atm, preferably 0.2 to 0.6 atm. The pressure in the case of performing pressure filtration can be, for example, 1.0 to 2.0 atm, preferably 1.0 to 1.6 atm.

In a preferred embodiment, the filtration rate is 0.3 atm with a filter having a pore size of 5 μm and an effective area of 9.0 cm ² , and the ratio (permeability) of the permeated metal powder paste to the input metal powder paste is, for example, 30 After 2 seconds, it is 35% by mass or more, preferably 40% by mass or more, more preferably 45% by mass or more, particularly preferably 50% by mass or more, and after 8 minutes, for example, 55% by mass or more, preferably 60% by mass. % Or more.

<Dispersed state of metal powder (A1) in metal powder paste>
In order to form a fine wiring or an ultrathin conductive layer (electrode), it is preferable to remove excessively or aggregated metal powder (A1) contained therein. According to the present invention, the metal powder paste before filtration is in an easily filtered state, that is, the particle size of the contained metal powder (A1) is sufficiently small and the aggregation is sufficiently reduced, and the filtration operation is easy. And it is excellent in that it is in a dispersed state of the metal powder (A1) so that a sufficiently high transmittance can be achieved. Moreover, the dispersion state of the metal powder (A1) is excellent so that the metal powder paste according to the present invention can be used without filtration if desired.

<Flatness of coating film with metal powder paste>
The flatness of the coating film by the metal powder paste is measured by n = 3 in accordance with JIS-BO601 using a contact type surface roughness meter (SE-3400, manufactured by Kosaka Laboratory) with the maximum peak height Rz of the coating film. And it can evaluate by calculating | requiring an average value. The metal powder paste reflects the low cohesiveness and high dispersibility of the surface-treated metal powder, and the coating film has a small Rz and can exhibit high flatness.

<Electrode with metal powder paste>
In a preferred embodiment, the metal powder paste according to the present invention can be applied to a substrate and then sintered to produce an electrode. A sintered body (electrode) produced by sintering is suitable as a flat thin layer electrode. Therefore, in particular, it can be suitably used as an internal electrode of a chip multilayer ceramic capacitor. Since this chip multilayer ceramic capacitor can be mounted in a small and high density, it can be suitably mounted and used on the inner layer or outermost layer of a multilayer board, and can be preferably mounted on an electronic component. it can.

According to a preferred embodiment of the present invention, the electrode (sintered body) manufactured by sintering is preferably SiO ₂ , TiO ₂ , or Al ₂ O having a diameter of 10 nm or more in its cross section. Any of ₃ may be present. In a preferred embodiment, the sintered body is present in a cross-section in which any one of SiO ₂ , TiO ₂ , or Al ₂ O ₃ having a maximum diameter of 0.5 μm or more is present at 0.5 pieces / μm ² or less. Or may be present, for example, in the range of 0.1 to 0.5 / μm ² . This maximum diameter means the diameter of the minimum circumscribed circle of the SiO ₂ , TiO ₂ , or Al ₂ O ₃ particles. In a preferred embodiment of the present invention, the deposition of SiO ₂ , TiO ₂ , or Al ₂ O ₃ particles is thus controlled, allowing the formation of ultrathin electrodes, while at the same time providing electrode reliability ( Quality).

  As described above, a metal powder paste (conductive paste) can be produced using the surface-treated metal powder (A1). Even when the surface-treated metal powder (A1) is dispersed in the hydrocarbon compound (B) to produce a metal powder paste, the metal powder (A1) is easily dispersed without agglomeration in the paste. And since the obtained electroconductive paste has reduced aggregation of metal powder (A1) particle | grains, the flat coating film calculated | required by a thin layer electrode can be formed easily, and a flat thin layer Suitable for forming electrodes. Thus, the surface-treated metal powder (A1) and the conductive paste using the same are excellent in workability, productivity, and sintering delay, and are used as a dispersion medium for the metal powder (A1). Since the hydrogen compound (B) is excellent in evaporability and decomposability, an electrode having excellent conductivity can be obtained without affecting the sintering of the metal powder (A1).

<Manufacture of metal powder (A)>
Copper powder, nickel powder, and silver powder were prepared as metal powder.

(Copper powder)
20 g of copper powder subjected to the surface treatment was produced by a wet method using a disproportionation method. Specifically, this was performed according to the following procedure.
(1) Addition of 50 g of cuprous oxide to 0.2 g of gum arabic + 350 mL of pure water.
(2) Add 50 mL of dilute sulfuric acid (25 wt%) at a time.
(3) After stirring with a rotating blade (300 rpm × 10 minutes), left for 60 minutes.
(4) The produced precipitate is washed.
The obtained copper powder had the following characteristics. The measurement used the laser diffraction type particle size distribution measuring apparatus (SALD-2100 made by Shimadzu Corporation).
D50: 0.12 μm, Dmax: 0.28 μm, distribution: one mountain

(Nickel powder)
As the nickel powder, NF32 (D50 0.3 μm) manufactured by Toho Titanium was used.

(Silver powder)
Milling according to JP 2007-291513 A. That is, 12.6 g of silver nitrate was dissolved in 0.8 L of pure water, 24 mL of 25% ammonia water and 40 g of ammonium nitrate were added to prepare a silver ammine complex salt aqueous solution. 1 g / L of gelatin was added thereto, and this was used as an electrolyte solution. Electrodeposited silver particles were electrolyzed at a current density of 200 A / m ² and a solution temperature of 20 ° C. using a DSE plate for both the anode and cathode. Was electrolyzed for 1 hour while scraping off the electrode plate. The silver powder thus obtained was filtered with Nutsche, washed with pure water and alcohol in that order, and dried at 70 ° C. for 12 hours in an air atmosphere. This silver powder was subjected to dry classification to finally obtain a silver powder having a D50 of 0.1 μm and a Dmax of 0.4 μm.

<Coupling agent aqueous solution>
The following silane was used as a coupling agent (C) having an amino group, and 50 mL of a 2 vol% coupling agent aqueous solution was prepared.
Silane: Diaminosilane A-1120 (made by MOMENTIVE)
Aminosilane A-1110 (made by MOMENTIVE)
Epoxy silane Z-6040 (manufactured by Toray Dow Corning)

The structural formula of diaminosilane used is as follows.
Diaminosilane _{A-1120: H 2 N-} C 2 H 4 -NH-C 3 H 6 -Si (OCH 3) 3
Aminosilane _{A-1110: H 2 N-} C 3 H 6 -Si (OCH 3) 3
Epoxysilane Z-6040:

[Examples 1 to 12, Comparative Examples 1 to 9]
<Preparation of surface-treated metal powder (A1)>
The supernatant liquid is removed from the copper powder slurry obtained by the above wet method, and 20 g of the copper powder is put into 50 mL of the coupling agent aqueous solution prepared without drying, and the coupling agent aqueous solution and the copper powder are added for 60 minutes. Mixing under stirring and sonication under conditions.
Stirring conditions: Rotating feathers (300 rpm)
Ultrasonic treatment: output 100 W, frequency 100 kHz (ultrasonic cleaner 3 frequency type / W-113, manufactured by Techjam Corporation)
Next, the aqueous coupling agent solution in which the copper powder was dispersed was suction filtered with an aspirator, and then pure water was added to the separated copper powder and further filtered. Washing by filtration is performed when ICP analysis is performed on a filtrate obtained by adding pure water 5 times the dry mass of the copper powder after washing and filtering, and Si, Ti, Al, Zr, Ce derived from the coupling agent Or it carried out until the element of Sn became a density | concentration of 50 ppm or less. In the above case, about 350 mL of pure water for cleaning was required. Therefore, the ICP analysis was performed on about 100 mL of the filtrate by filtering about 100 mL after filtering the last about 350 mL. The obtained copper powder was dried at 70 ° C. for 1 hour under a nitrogen atmosphere, and crushed in a mortar to obtain a surface-treated copper powder.
Nickel powder and silver powder were respectively added to 50 mL of a coupling agent aqueous solution in which 20 g was prepared, and surface-treated nickel powder and silver powder were obtained in the same manner as the above copper powder.
About the metal powder (A1) of Examples 1-12 and Comparative Examples 1-9, the kind of metal powder and coupling agent which were used are shown in Table 1.

<Evaluation of surface-treated metal powder (A1)>
The surface-treated copper powder, nickel powder, and silver powder obtained by the above-described operation were evaluated by the following methods.

<Size of metal powder (A1)>
About the magnitude | size of the metal powder, it measured by the laser diffraction type particle size distribution measurement (Shimadzu Corporation SALD-2100). The copper powder after the surface treatment was D50: 0.12 μm, Dmax: 0.29 μm, and distribution: one mountain.

<Thermomechanical characteristics of metal powder (A1)>
A sample was prepared for the surface-treated metal powder, and the sintering start temperature was measured using TMA (Thermomechanical Analyzer). The conditions for sample preparation and thermomechanical properties are as follows.
Sample preparation conditions Compact size: 7 mmφ x 5 mm Height Molding pressure: 1 Ton / cm ² (1000 kg weight / cm ² )
(0.5 wt% zinc stearate added as a lubricant)
Measurement condition equipment: Shimadzu Corporation TMA-50
Temperature rise: 5 ° C./min Atmosphere: ₂ vol% H ₂ —N ₂ (300 cc / min)
Load: 98.0mN

As described above, 0.5% by mass of zinc stearate is added to the metal powder and mixed, and this mixture is loaded into a cylinder with a diameter of 7 mm. The punch is pushed in from the top and held at 1 Ton / cm ² for 3 seconds. And it shape | molded in the column shape of about 5 mm in height. This molded body was loaded into a temperature raising furnace under a condition that the axis was vertical and a load of 98.0 mN was applied in the axial direction, and the temperature was raised at a flow rate of ₂ vol% H ₂ -N ₂ (300 cc / min). The temperature was continuously raised to a rate of 5 ° C./minute and a measurement range: 50 to 1000 ° C., and the height change (change in expansion / contraction) of the compact was automatically recorded. The temperature at which the height change (shrinkage) of the molded body started and the shrinkage rate reached 1% was defined as “sintering start temperature”.
Table 1 shows sintering start temperatures of the metal powders (A1) of Examples 1 to 12 and Comparative Examples 1 to 9.
The sintering start temperatures of the metal powders surface-treated with diaminosilane A-1120 and aminosilane A-1110 were both 600 ° C. or higher. On the other hand, the sintering start temperature of the metal powder surface-treated with epoxysilane Z-6040d did not exceed 450 ° C.

<Element amount in the surface treatment layer>
Si, N, and C adsorbed on the surface of the surface-treated metal powder were analyzed under the following conditions.
Si adsorption amount: The surface-treated metal powder is dissolved with an acid, quantified by ICP (inductively coupled plasma atomic emission spectrometry), and the mass of Si relative to the unit mass (g) of the surface-treated metal powder ( μg) was calculated.
N, C adsorption amount: The surface treated copper powder is melted at a high temperature, the N, C adsorption amount is calculated from the amount of NO ₂ and CO ₂ generated, and N attached to the entire surface of the copper powder The amount of N and C relative to the surface-treated copper powder was determined by measuring the amount of C.
Table 1 shows the amounts of Si adsorption and N adsorption of the metal powders (A1) of Examples 1 to 12 and Comparative Examples 1 to 9.
In any of the metal powders surface-treated with diaminosilane A-1120 and aminosilane A-1110, 100 g or more of Si as the central element of the coupling agent is 1 g of metal powder, and N is 0 with respect to the metal powder. .02% by mass or more was adsorbed. On the other hand, any metal powder surface-treated with epoxysilane Z-6040d adsorbed 100 μg or more of Si, which is the central element of the coupling agent, to 1 g of metal powder, but the amount of N adsorbed to the metal powder was 0. It was mass%.

<Manufacture of metal powder paste>
Two types of polybutene (HV300: number average molecular weight Mn = 1400, kinematic viscosity (40 ° C.) = 26,000 mm ² / s, HV15: Mn = 630, metal powder surface-treated with aminosilane or diaminosilane were used as dispersion media. Kinematic viscosity (40 ° C.) = 655 mm ² / s, all manufactured by JX Energy Co., Ltd.) and kneaded with a mixer to produce metal powder pastes according to Examples 1-12. The mass ratio of metal powder: polybutene at this time was 76:24. As a comparative example, the surface-treated metal powder is dispersed in a solvent (α-terpineol: TPO) in which a fatty acid (oleic acid; C18, one double bond) and a binder (ethylcellulose) are dissolved as a dispersion medium. A metal powder paste was produced. The metal powder: solvent: binder: fatty acid mass ratio of Comparative Examples 1, 2, 4, 5, 7, and 8 was 60: 37: 2: 1. Furthermore, the metal powder surface-treated with epoxysilane was mixed with polybutene (HV300: number average molecular weight Mn = 1400, kinematic viscosity (40 ° C.) = 26,000 mm ² / s, manufactured by JX Energy Co., Ltd.), and a mixer The metal powder paste according to Comparative Examples 3, 6, and 9 was produced.

<Coating film of metal powder paste>
The metal powder paste obtained by the above procedure was applied on an alumina substrate by screen printing. The coating films produced with the metal powder pastes of Examples 1 to 12 and Comparative Examples 1, 2, 4, 5, 7 and 8 were all free from coating film failure and had good coatability. On the other hand, with respect to the coating films prepared from the metal powder pastes of Comparative Examples 3, 6 and 9, the coatability was poor.

<Sintering of coating film and evaluation of sintered body>
The coating films produced from the metal powder pastes of Examples 1 to 12 and Comparative Examples 1 to 9 were dried at 120 ° C. for 10 minutes in an air atmosphere. Thereafter, firing was performed at 850 ° C. for 30 minutes in a firing furnace in a nitrogen atmosphere to obtain a sintered body. The sintered body was subjected to visual appearance and SEM observation. The results are listed in Table 1. The SEM images of Example 2 and Comparative Example 1 are shown in FIGS. 1 and 2, respectively.

As shown in FIGS. 1 and 2 and Table 1, in the sintered bodies prepared from the metal powder pastes of Comparative Examples 1, 2, 4, 5, 7, and 8, the metal powder shape was observed in SEM observation. It can be confirmed that the sintered bodies prepared from the metal powder pastes of Examples 1 to 12 and the comparative example are excellent in sinterability without the shape of the metal powder being observed under the same firing conditions.
Moreover, the base | substrate was exposed by the external appearance (visual observation) of the sintered compact produced from the metal powder paste of Comparative Examples 3, 6, and 9.

  The metal powder paste of the present invention is excellent in evaporability, decomposability, and coatability, has high chemical stability, and has a sintering delay. Therefore, for example, it can be suitably used for the production of internal electrodes of chip multilayer ceramic capacitors.

Claims (10)

Surface treatment to obtain metal powder (A1) in which 100 to 2000 μg of any one or more metals among Si, Ti, Al, Zr, Ce, and Sn and N are adsorbed to 1 g of metal powder (A) Process,
A paste preparation step of preparing a paste by dispersing the metal powder (A1) in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s. Manufacturing method of paste.   The said surface treatment process makes it adsorb | suck so that N may be 0.02 mass% or more with respect to the said metal powder (A1), The manufacturing method of the metal-powder paste of Claim 1 characterized by the above-mentioned. 3. The method for producing a metal powder paste according to claim 1, wherein the hydrocarbon compound (B) has a kinematic viscosity at 40 ° C. of 500 to 10,000 mm ² / s.   The said hydrocarbon compound (B) contains polybutene (B1), The manufacturing method of the metal-powder paste as described in any one of Claims 1-3 characterized by the above-mentioned. A filtration step of filtering the metal powder paste produced by the method for producing a metal powder paste according to any one of claims 1 to 4 with a filter;
A printing process in which the metal powder paste filtered in the filtration process is screen-printed on a green sheet;
A method for screen printing a metal powder paste, comprising: An application step of applying the metal powder paste manufactured by the method of manufacturing a metal powder paste according to any one of claims 1 to 4 to a substrate;
A sintering step of heating and sintering the metal powder paste applied to the substrate in the application step to form an electrode;
The manufacturing method of the electrode characterized by including.   The method of manufacturing an electrode according to claim 6, wherein in the sintering step, the metal powder paste is heated and sintered to form an electrode having a metallic luster. An application step of applying the metal powder paste manufactured by the method of manufacturing a metal powder paste according to any one of claims 1 to 4 to a substrate;
Laminating the base material coated with the metal powder paste, integrating by applying pressure, and then singulation into chips,
A sintering step of heating and sintering the chip;
A method for manufacturing a chip multilayer ceramic capacitor, comprising: One to one metal of Si, Ti, Al, Zr, Ce, and Sn is adsorbed to 100 to 2000 μg and N adsorbed to 1 g of metal powder (A), D50 is 0.5 μm or less, and Dmax is The surface-treated metal powder (A1) having a size of 1.0 μm or less is dispersed in a hydrocarbon compound (B) having a kinematic viscosity at 40 ° C. of 500 to 30000 mm ² / s, and the metal powder (A1) is dispersed. Is a metal powder paste characterized in that N is adsorbed by 0.02% by mass or more.   The metal powder paste according to claim 9, wherein a sintering start temperature of the metal powder (A1) is 350 ° C or higher.