JP7002483B2 - Conductive composition - Google Patents

Description

The present disclosure relates to conductive compositions.

Conventionally, as a conductive material for producing a composite of a ceramic and a conductor, such as when forming an electrode or a circuit on the surface of a ceramic substrate, metal particles such as Ag, Cu, Ni or Pt and a glass powder having a low softening point are used. A conductive composition in which and is mixed in an organic vehicle is generally known. As a method for producing a composite of ceramic and a conductor, a method of simultaneously firing a green sheet containing ceramic and a conductive composition (cofire method) is known. For example, a chip laminated ceramic capacitor is manufactured by printing a conductive composition for an electrode layer on a green sheet (dielectric sheet) by a screen printing method and then performing a firing step at a high temperature of about 1000 ° C.

Such a conductive composition is required to have excellent adhesion to a ceramic substrate after firing. Therefore, for example, Japanese Patent Application Laid-Open No. 2006-73836 (Patent Document 1) describes a conductive composition for ceramic electronic parts containing rosin or terpene oil polymerized resin that can be obtained from pine fat in order to improve the adhesion to the ceramic prime field. Is disclosed.

Further, Japanese Patent Application Laid-Open No. 2005-267858 (Patent Document 2) describes a conductive paste for an internal electrode containing nickel powder, in order to suppress delamination generated in the sintered body when the temperature is lowered after the completion of firing. Disclosed is a technique of adding a ceramic powder of the same type or similar to the body layer to a conductive paste as a co-material to suppress a difference in thermal shrinkage behavior between the dielectric layer and the internal electrode layer.

Japanese Unexamined Patent Publication No. 2006-73836 Japanese Unexamined Patent Publication No. 2005-267858

When industrially producing a composite of ceramic and conductor, high adhesion between the two is of course an important characteristic, but not only that, but also the high conductivity and high productivity of the conductor. It is desirable to combine them.

Therefore, an object of the present disclosure in one aspect is to provide a conductive composition having the following three properties.
(1) The conductor obtained by sintering is excellent in conductivity.
(2) Contributes to improving the productivity of the composite of ceramic and conductor.
(3) Excellent adhesion to ceramic when a composite of ceramic and conductor is manufactured by the cofire method.

In order to solve the above problems, the present inventor first examined the improvement of productivity in the case of producing a composite of a ceramic and a conductor by using the cofire method. Then, they have found that it is effective to bake in a steam atmosphere in order to improve the desorption rate of the binder resin contained in the green sheet and the binder resin contained in the conductive composition. This is due to the large permeation action of the heated steam into the object to be fired.

Next, the present inventor examined means for improving the adhesion between the ceramic and the conductor. In order to suppress the peeling of the ceramic and the conductor during the cooling process after firing (≈ deterioration of adhesion), it is possible to reduce the difference in heat shrinkage behavior between the metal powder contained in the conductive composition and the ceramic. Desired. As one of the means, it is effective to raise the sintering start temperature of the metal powder contained in the conductive composition, in other words, to increase the sintering delay property.

In this regard, the present inventor has studied diligently and found that it is effective to mix at least one of cuprous oxide powder and copper oxide powder in a conductive composition containing copper powder in a predetermined amount. According to this method, it was found that even when the conductive composition is fired in a steam atmosphere, the effect of improving the sintering delay property is exhibited and a sintered body having excellent conductivity can be obtained.

The present invention has been completed based on the above findings, and is exemplified below.
(1)
A conductive composition comprising copper powder, one or both oxidation fillers selected from the group consisting of cuprous oxide powder and copper oxide powder, a binder resin, and a dispersion medium.
The conductive composition is applied onto a slide glass at a moving speed of 5 cm / sec using an applicator with a 25 μm gap, dried at 120 ° C. for 10 minutes, and then coated with a stylus type roughness meter. Arithmetic mean roughness Ra in the direction is 0.2 μm or less,
In the XRD of the coating film, the ratio of the peak area corresponding to the oxide filler on the (111) plane to the peak area corresponding to the copper powder on the (111) plane was 0.05 to 0.5.
From 0.5 g of powder obtained by crushing the coating film, a columnar green compact having a density of 4.7 ± 0.2 gcm ^-3 and a diameter of 5 mm was formed, and a load of 98 mN was applied to the green compact. The volume shrinkage at 650 ° C. is 15% or less when TMA is measured at a temperature rise rate of 1 ° C./min in a residual nitrogen atmosphere with a total pressure of 1 atm and a partial pressure of water vapor of 0.05 atm while being applied to the upper bottom surface.
Conductive composition.
(2)
A sintered body obtained by heating the conductive composition to 850 ° C. at a heating rate of 1 ° C./min at a residual nitrogen atmosphere with a total pressure of 1 atm and a partial pressure of water vapor of 0.03 atm, and firing at 850 ° C. for 30 minutes. The conductive composition according to (1), wherein the total concentration of Si, Ti, Al and Zr is 1000 to 10000 mass ppm when measured by ICP emission spectroscopic analysis method.
(3)
A sintered body obtained by heating the conductive composition to a total pressure of 1 atm, a residual nitrogen atmosphere of a water vapor partial pressure of 0.03 atm, a rate of 0.75 ° C./min to 850 ° C., and firing at 850 ° C. for 20 minutes. The conductive composition according to (1) or (2), which has a specific resistance of 3.0 μΩ · cm or less.
(4)
The conductive composition according to any one of (1) to (3), wherein the copper powder and / or the oxide filler is surface-treated with a coupling agent.
(5)
Any of (1) to (4), which comprises kneading a copper powder, one or both oxide fillers selected from the group consisting of cuprous oxide powder and copper oxide powder, a binder resin, and a dispersion medium. The method for producing a conductive composition according to item 1.
(6)
The method for producing a conductive composition according to (5), wherein the copper powder has a bulk density of 3.0 g / cm ³ or less.
(7)
The production method according to (5) or (6), wherein the ratio of the BET specific surface area of the oxide filler to the BET specific surface area of the copper powder is 0.2 to 3.0.
(8)
The production method according to any one of (5) to (7), wherein the ratio of the mass of the oxide filler to the total mass of the copper powder and the oxide filler is 0.05 to 0.35.
(9)
A composite of a ceramic and a conductor produced by using the conductive composition according to any one of (1) to (4).
(10)
A laminated ceramic capacitor manufactured by using the conductive composition according to any one of (1) to (4).
(11)
A ceramic circuit board manufactured by using the conductive composition according to any one of (1) to (4).

In one embodiment, the conductive composition according to the present disclosure is excellent in conductivity when made into a sintered body. Further, the conductive composition according to the present disclosure is suitable for firing in a steam atmosphere for improving productivity in one embodiment. Further, in one embodiment, the conductive composition according to the present disclosure is excellent in adhesion to the ceramic when a composite of the ceramic and the conductor is produced by the cofire method.

The present disclosure will be described in detail below with reference to embodiments. The present disclosure is not limited to the specific embodiments listed below.

[Conductive composition]
In one embodiment, the conductive composition according to the present disclosure contains copper powder, one or more oxidation fillers selected from the group consisting of cuprous oxide powder and copper oxide powder, a binder resin, and a dispersion medium. The conductive composition can be produced by kneading these various components. Kneading can be performed using known means. The conductive composition is provided as a paste in one embodiment.

In one embodiment, the stylus roughness of the coating film after the conductive composition is applied onto a glass slide at a moving speed of 5 cm / sec using a 25 μm gap applicator and dried at 120 ° C. for 10 minutes. The arithmetic mean roughness Ra in the coating direction by the meter is 0.2 μm or less. The arithmetic mean roughness Ra is expressed as an average value when measured at a plurality of points with a stylus type roughness meter in accordance with JIS B0633: 2001. When the arithmetic mean roughness Ra becomes large, voids are likely to occur at the interface between the conductor and the ceramic when the composite of the ceramic and the conductor is manufactured by the cofire method, and the bonding strength between the two is likely to decrease. The arithmetic mean roughness Ra is preferably 0.1 μm or less, and more preferably 0.05 μm or less.

In one embodiment, when XRD (X-ray diffraction) measurement is performed on the coating film, the ratio of the peak area corresponding to the oxide filler on the (111) plane to the peak area corresponding to the copper powder on the (111) plane is determined. It is 0.05 to 0.5. When the ratio is 0.05 or more, preferably 0.1 or more, the sintering delay property is significantly improved. Further, when the ratio is 0.5 or less, preferably 0.3 or less, excellent conductivity can be ensured.

The peak area corresponding to the copper powder on the (111) plane represents the peak area of copper on the (111) plane. The peak area corresponding to the oxide filler on the (111) plane represents the peak area of the cuprous oxide on the (111) plane when only the cuprous oxide powder is used as the oxide filler, and when only the copper oxide powder is used as the oxide filler. Represents the peak area of copper oxide on the (111) plane, and when both cuprous oxide powder and copper oxide powder are used as the oxide filler, the peak area of cuprous oxide and the peak area of copper oxide on the (111) plane Represents the total.

In one embodiment, a columnar green compact having a density of 4.7 ± 0.2 gcm ^-3 and a diameter of 5 mm is formed from 0.5 g of the powder obtained by crushing the coating film, and a load of 98 mN is applied. The volume shrinkage at 650 ° C. is 15% or less when TMA is measured at a temperature rise rate of 1 ° C./min in a residual nitrogen atmosphere with a total pressure of 1 atm and a partial pressure of water vapor of 0.05 atm while applying Is. The small volume shrinkage means that the sintering delay property in a water vapor atmosphere is excellent. The volume shrinkage is preferably 15% or less, and more preferably 10% or less. The volume shrinkage is most preferably 0%, but is usually 2% or more, typically 5% or more.

In a preferred embodiment, the conductive composition is heated to 850 ° C. with a residual nitrogen atmosphere at a total pressure of 1 atm and a steam partial pressure of 0.03 atm at a heating rate of 1 ° C./min and calcined at 850 ° C. for 30 minutes. The total concentration of Si, Ti, Al and Zr when the obtained sintered body is measured by ICP emission spectroscopic analysis is 1000 to 10000 mass ppm. When the total concentration is 1000 mass ppm or more, the sintering delay property in a steam atmosphere is further improved. When the total concentration is 10,000 mass ppm or less, it is possible to suppress deterioration of the conductivity and heat dissipation of the sintered body. The total concentration is preferably 1500 to 7000 mass ppm, more preferably 1500 to 4000 mass ppm.

Sintering obtained by heating the conductive composition to a total pressure of 1 atm, a residual nitrogen atmosphere of a water vapor partial pressure of 0.03 atm, a rate of 0.75 ° C./min to 850 ° C., and firing at 850 ° C. for 20 minutes. The specific resistance of the body is preferably 3.0 μΩ · cm or less, more preferably 2.5 μΩ · cm or less, and can be, for example, 1.7 to 3.0 μΩ · cm.

In one embodiment, the conductive composition according to the present disclosure can be used to produce a composite of a ceramic and a conductor. As a method for producing a composite of ceramic and a conductor, a method of simultaneously firing a green sheet (dielectric sheet) containing ceramic and a conductive composition (cofire method) can be preferably adopted. In particular, by using the conductive composition according to the present disclosure, even if firing is performed in a steam atmosphere in order to increase productivity, the specific resistance of the conductor is small and the adhesion between the ceramic and the conductor is improved. An excellent conductor / ceramic composite can be obtained. This property is at least partially due to the fact that the oxide filler contained in the conductive composition has excellent sintering delay even in a steam atmosphere.

Since the sintered body obtained by firing the conductive composition according to the present disclosure is a conductor, it can be used, for example, as an electrode or a circuit. For example, a laminated ceramic capacitor can be manufactured by applying a conductive composition for an electrode layer on a green sheet by a screen printing method or the like, and then undergoing a firing step of, for example, 500 to 1000 ° C. In this case, the sintered body of the conductive composition is used as an internal electrode of a laminated ceramic capacitor. Similarly, the ceramic circuit board can be manufactured by applying a conductive composition for circuit formation on a green sheet by a screen printing method or the like, and then undergoing a firing step of, for example, 400 to 1000 ° C.

[Copper powder]
The copper powder includes pure copper powder and copper alloy powder (particularly, copper alloy powder having a Cu content of 80% by mass or more).

The BET specific surface area of the copper powder is preferably 1.5 to 10 m ² / g, more preferably 1.5 to 5 m ² / g. Here, the BET specific surface area is measured according to JIS Z 8830: 2013 after degassing the copper powder in vacuum at 200 ° C. for 5 hours. The BET specific surface area can be measured using, for example, BELSORP-miniII manufactured by Microtrac Bell.

The concentration of the copper powder in the conductive composition is preferably 20% by mass or more, more preferably 25% by mass or more, from the viewpoint of improving the coating film density and, by extension, the electrode density. Further, the concentration of the copper powder in the conductive composition is preferably 90% by mass or less, more preferably 85% by mass or less, from the viewpoint of printability.

The higher the dispersibility of the copper powder, the easier it is for the oxide filler described later to enter the gaps of the copper powder, and the higher the sintering delay property. In addition, the surface roughness of the coating film can be reduced. Therefore, it is preferable that the bulk density, which is an index of the dispersibility of the copper powder, is low. Specifically, the bulk density of the copper powder is preferably 3.0 g / cm ³ or less, and more preferably 2.5 g / cm ³ or less. However, the bulk density of the copper powder is preferably 1.0 g / cm ³ or more because if the bulk density of the copper powder is too low, the bulk of the copper powder becomes large and it is difficult to handle when adjusting the conductive composition. More preferably, it is 5 g / cm ³ or more. The bulk density can be lowered, for example, by performing a pH treatment step in which the copper powder is brought into contact with an alkaline aqueous solution having a pH of 8 to 14.

Bulk density is measured by the following procedure. A guide is attached to a 10 cc cup having a diameter of 2 cm, powder exceeding 10 cc is put in, and tapping is performed 1000 times. Next, leaving the guide, the portion exceeding the volume of 10 cc is scraped off, and the density obtained based on the weight of the powder contained in the cup and the volume of the cup (10 cc) in this state is the solid bulk density. The bulk density can be measured using, for example, Powder Tester PT-X (Hosokawa Micron).

As the copper powder, either the copper powder produced by the dry method or the copper powder produced by the wet method can be used. When the copper powder produced by the wet method is used, it is suitable in that the wet process is consistently performed up to the surface treatment with the coupling agent described later.

A suitable method for producing copper powder by a wet method will be exemplified. The production method involves adding a dispersant (for example, gum arabic, gelatin, collagen peptide, surfactant, etc.) to the cuprous oxide powder slurry, and then adding dilute sulfuric acid to the slurry at once within 5 seconds. The step of performing the disproportionation reaction is included. In a preferred embodiment, the slurry can be kept at room temperature (20 to 25 ° C.) or lower, and dilute sulfuric acid similarly kept at room temperature or lower can be added to carry out a disproportionation reaction. The BET specific surface area (size, bulk density) of the copper powder can be controlled by the addition amount of the dispersant, the addition rate of dilute sulfuric acid, and the like. As an example, when the amount of organic matter such as gum arabic is large, the BET specific surface area tends to be large, and when the addition rate of dilute sulfuric acid is high, the BET specific surface area tends to be large. In a preferred embodiment, the dilute sulfuric acid can be added so that the slurry has a pH of 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 should be within 5 minutes, preferably within 1 minute, more preferably within 30 seconds, even more preferably within 10 seconds, still more preferably within 5 seconds. , Can be added. In a preferred embodiment, the disproportionation reaction can be completed within 10 minutes, for example, within 5 seconds if the addition of dilute sulfuric acid to the slurry is instantaneous. In a preferred embodiment, the concentration of the dispersant such as gum arabic in the slurry before the addition of dilute sulfuric acid can be 0.2 to 1.2 g / L. The principle of this disproportionation reaction is as follows:
Cu ₂ O + H ₂ SO ₄ → Cu ↓ + Cu SO ₄ + H ₂ O
The copper powder obtained by this disproportionation can be washed, rust-proofed, filtered, dried, crushed, and classified, if desired. When the surface is treated with an aqueous solution of a coupling agent, the copper powder slurry obtained after cleaning, rust prevention, and filtration can be mixed with the aqueous solution of the coupling agent as it is without drying.

[Oxidation filler]
Along with copper powder, one or both oxide fillers selected from the group consisting of cuprous oxide powder (Cu ₂ O powder) and copper oxide powder (CuO), preferably reduced to Cu during firing, contribute to improving conductivity. By blending the easily liable cuprous oxide powder (Cu ₂ O powder) into the conductive composition, the sintering start temperature of the copper powder is significantly increased. Although not intended to limit the present invention by theory, when the particle size is the same, the cuprous oxide powder and the copper oxide powder are less likely to be sintered than the copper powder in a non-reducing atmosphere, and shrink at a higher temperature side. Since the sintering of copper powder proceeds from the portion where the copper powders are in contact with each other, such sub-copper oxide powder and copper oxide enter between the copper powders, thereby hindering the contact between the copper powders. It is considered to inhibit sintering.

The BET specific surface area of the oxide filler is preferably 1 to 5 m ² / g, more preferably 1.5 to 4.5 m ² / g. Here, the BET specific surface area is measured according to JIS Z 8830: 2013 after degassing the oxide filler (measured for each oxide filler when a plurality of types are used) in a vacuum at 200 ° C. for 5 hours. Ru.

The ratio of the BET specific surface area of the oxide filler to the BET specific surface area of the copper powder is preferably 0.2 or more because the larger the ratio, the easier it is for the oxide filler to enter the gaps of the copper powder. However, when the particle size of the oxide filler is reduced and the ratio becomes too large, the difference between the sintering start temperature of the oxide filler and the sintering start temperature of the copper powder becomes small, and the oxide filler is contained in the conductive composition. As a result, the effect of improving the sintering delay may be reduced. Therefore, the ratio of the BET specific surface area of the oxide filler to the BET specific surface area of the copper powder is preferably 3.0 or less, more preferably 2.0 or less, and further preferably 1.5 or less. More preferred.

The ratio of the mass of the oxide filler to the total mass of the copper powder and the oxide filler is preferably 0.05 or more from the viewpoint of enhancing the sintering delay. Further, the ratio is preferably 0.35 or less, and more preferably 0.30 or less, from the viewpoint of increasing the conductivity of the sintered body.

[Coupling agent]
It is desirable that at least one of the copper powder and the oxide filler, preferably both, is surface-treated with a coupling agent. Specifically, it is more preferable that the surface is treated with a coupling agent containing one or more elements selected from the group consisting of Si, Ti, Al and Zr. When the copper powder and / or the oxide filler is surface-treated with a coupling agent, the adhesion between the ceramic and the conductor can be improved in the conductor-ceramic composite.

Examples of the coupling agent include a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a zirconate coupling agent. One type of coupling agent may be used, or two or more types may be used in combination. As the coupling agent, Si was used when a silane coupling agent was used, Ti was used when a titanate coupling agent was used, Al was used when an aluminate coupling agent was used, and a zirconate coupling agent was used. In some cases, Zr can be attached to the surfaces of the copper powder and the oxide filler, respectively.

As the silane coupling agent, aminosilane can be preferably used. In a preferred embodiment, a silane containing one or more amino groups and / or imino groups can be used as the aminosilane. The number of amino groups and imino groups contained in the aminosilane can be, for example, 1 to 4, preferably 1 to 3, and more preferably 1 to 2, respectively. In a preferred embodiment, the number of amino groups and imino groups contained in aminosilane can be one each. Aminosilane having a total number of amino groups and imino groups contained in aminosilane of 1 can be referred to as monoaminosilane in particular, aminosilane having 2 can be referred to as diaminosilane, and aminosilane having 3 can be referred to as triaminosilane. .. In particular, monoaminosilane and diaminosilane can be preferably used. In a preferred embodiment, a monoaminosilane containing one amino group can be used as the aminosilane. In a preferred embodiment, the aminosilane can contain at least one, eg, one amino group, at the end of the molecule, preferably at the end of a linear or branched chain molecule.

Examples of the aminosilane include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 1-. Aminopropyltrimethoxysilane, 2-aminopropyltrimethoxysilane, 1,2-diaminopropyltrimethoxysilane, 3-amino-1-propenyltrimethoxysilane, 3-amino-1-propynyltrimethoxysilane, 3- Aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl- 3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- (N-phenyl) amino Propyltrimethoxysilane can be mentioned.

In a preferred embodiment, the aminosilane represented by the following formula I can be used.
H ₂ N-R ¹ -Si (OR ² ) ₂ (R ³ ) (Equation I)
In the above formula I,
R ¹ is a hydrocarbon of C1 to C12 having a linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic. It is a divalent group of
R ² is an alkyl group of C1 to C5.
R ³ is an alkyl group of C1 to C5 or an alkoxy group of C1 to C5.

In a preferred embodiment, R ¹ of the above formula I has a linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic ring or heterocyclic ring. C1-C12 hydrocarbon divalent groups without, more preferably R ¹ is a substituted or unsubstituted, C1-C12 linear saturated hydrocarbon divalent group, substituted or unsubstituted. , C1 to C12 branched saturated hydrocarbon divalent groups, substituted or unsubstituted, C1 to C12 linear unsaturated hydrocarbon divalent groups, substituted or unsubstituted, C1 to C12 minutes. Divalent groups of branched unsaturated hydrocarbons, substituted or unsubstituted, divalent groups of cyclic hydrocarbons of C1 to C12, substituted or unsubstituted, divalent groups of heterocyclic hydrocarbons of C1 to C12, It can be a group selected from the group consisting of substituted or unsubstituted divalent groups of aromatic hydrocarbons of C1 to C12. In a preferred embodiment, R ¹ of the above formula I is a divalent group of saturated or unsaturated chain hydrocarbons of C1 to C12, more preferably atoms at both ends of the chain structure are free atoms. It is a divalent group with a valence. In a preferred embodiment, the number of carbon atoms of the divalent group can be, for example, C1 to C12, preferably C1 to C8, preferably C1 to C6, and preferably C1 to C3.

In a preferred embodiment, R ¹ of the above formula I is − (CH ₂ ) _n −, − (CH ₂ ) _n − (CH) _m − (CH ₂ ) _j-1- , − (CH ₂ ) _n −. (CC)-(CH ₂ ) _n-1 -,-(CH ₂ ) _n -NH- (CH ₂ ) _m -,-(CH ₂ ) _n -NH- (CH ₂ ) _m -NH- (CH ₂ ) _j -,-(CH ₂ ) _n-1- (CH) NH _2- (CH ₂ ) _m-1 -,-(CH ₂ ) _n-1- (CH) NH _2- (CH ₂ ) _m-1- It can be a group selected from the group consisting of NH- (CH ₂ ) _j- (where n, m, j are integers of 1 or more). (However, the above (CC) represents a triple bond of C and C.) In a preferred embodiment, R ¹ is-(CH ₂ ) n- or-(CH ₂ ) n-NH- (CH ₂ ). ) M-. (However, the above (CC) represents a triple bond of C and C.) In a preferred embodiment, the hydrogen of R ¹ which is the above divalent group may be substituted with an amino group, for example, 1. Up to 3 hydrogens, such as 1-2 hydrogens, such as 1 hydrogen, may be substituted with amino groups.

In a preferred embodiment, n, m, and j in the above formula I may be independently an integer of 1 or more and 12 or less, preferably an integer of 1 or more and 6 or less, and more preferably an integer of 1 or more and 4 or less. It can be, for example, an integer selected from 1, 2, 3, 4 and can be, for example, 1, 2 or 3.

In a preferred embodiment, R ² of the above formula I can be an alkyl group of C1 to C5, preferably an alkyl group of C1 to C3, more preferably an alkyl group of C1 to C2, for example, a methyl group. It can be an ethyl group, an isopropyl group, or a propyl group, preferably a methyl group or an ethyl group.

In a preferred embodiment, R ³ of the above formula I can be an alkyl group of C1 to C5, preferably an alkyl group of C1 to C3, more preferably an alkyl group of C1 to C2, for example. , Methyl group, ethyl group, isopropyl group, or propyl group, preferably a methyl group or an ethyl group. Further, R ³ of the above formula I can be an alkoxy group of C1 to C5, preferably an alkoxy group of C1 to C3, more preferably an alkoxy group of C1 to C2, and for example, a methoxy group. It can be an ethoxy group, an isopropoxy group, or a propoxy group, preferably a methoxy group or an ethoxy group.

Examples of the titanate-based coupling agent include the following formula II:
(H ₂ N-R ¹ -O) _p Ti (OR ² ) _q (Equation II)
(However, in the above formula II,
R ¹ is a hydrocarbon of C1 to C12 having a linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic. It is a divalent group of
R ² is an alkyl group of C1 to C5 having a linear or branched structure.
p and q are integers of 1 to 3, and p + q = 4. )
Examples thereof include amino group-containing titanates represented by.

As R ¹ of the above formula II, the group listed as R ¹ of the above formula I can be preferably used. As R ¹ of the above formula II, for example,-(CH ₂ ) _n -,-(CH ₂ ) _n- (CH) _m- (CH ₂ ) _j-1 -,-(CH ₂ ) _n- (CC)- (CH ₂ ) _n-1 －, － (CH ₂ ) _n －NH－ (CH ₂ ) _m －, － (CH ₂ ) _n －NH－ (CH ₂ ) _m －NH－ (CH ₂ ) _j －, － (CH ₂ ) _n-1- (CH) NH _2- (CH ₂ ) _m-1 -,-(CH ₂ ) _n-1- (CH) NH _2- (CH ₂ ) _m-1 -NH- (CH 2) ₂ ) It can be a group selected from the group consisting of _j − (where n, m, j are integers of 1 or more). As a particularly suitable R ₁ ,-(CH ₂ ) _n -NH- (CH ₂ ) _m- (where n + m = 4, particularly preferably n = m = 2) can be mentioned.

As R ^{2 of the above formula II, the group listed as R 2 of} the above formula I can be preferably used. In a preferred embodiment, an alkyl group of C3 can be mentioned, and particularly preferably a propyl group and an isopropyl group. P and q in the above formula II are integers of 1 to 3, p + q = 4, and preferably a combination of p = q = 2 and a combination of p = 3 and q = 1.

In the above, the description has been made using a coupling agent having an amino group at the end, but the surface treatment of copper powder and the oxide filler with the coupling agent is a coupling agent having no amino group at the end (non-amino acid coupling). It can also be suitably carried out by using an agent). Examples of the non-amino-based coupling agent include coupling agents having an organic functional group such as an epoxy group, a mercapto group, an acryloyl group, a methacryloyl group, a vinyl group and an acid anhydride group at the terminal.

Examples of the silane coupling agent having an epoxy group include 3-glycidoxytrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldiethoxy. Examples thereof include silane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

Examples of the silane coupling agent having a mercapto group include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

Examples of the silane coupling agent having an acryloyl group include 3-acryloxypropyltrimethoxysilane.

Examples of the silane coupling agent having a methacryloyl group include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane. Can be mentioned.

Examples of the silane coupling agent having a vinyl group include vinyltrimethoxysilane and vinyltriethoxysilane.

Examples of the silane coupling agent having an acid anhydride group include 3-trimethoxysilylpropyl succinic acid anhydride and the like.

The coupling agent is preferably pretreated to promote the self-condensation reaction before being mixed with the copper powder and / or the oxidative filler. In one embodiment, in the pretreatment, an alkaline aqueous solution such as an aqueous ammonia solution, an aqueous NaOH solution, an aqueous KOH solution, or an aqueous monoethanolamine solution is added to the coupling agent, preferably pH 11.5 or more and 13.5 or less, more preferably pH 12. It includes a step of preparing an aqueous solution of a coupling agent adjusted to 0 or more and 13.5 or less, and a step of stirring while maintaining the aqueous solution of the coupling agent at 10 ° C to 40 ° C.

A higher pH can promote the self-condensation reaction of the coupling agent, but if the self-condensation reaction is promoted too much, the coupling agent gels and the dispersibility of the copper powder and / or the oxide filler decreases. As a result, the coating film becomes rough. Further, a longer stirring time can promote the self-condensation reaction to some extent, but a longer stirring time deteriorates productivity. Therefore, the stirring time can be preferably 1 to 72 hours, more preferably 6 to 24 hours.

The aqueous solution of the coupling agent after the pretreatment can be applied to the surface treatment of the copper powder and / or the oxide filler by a known method. For example, the pretreated aqueous coupling agent is mixed with copper powder and / or an oxide filler to form a dispersion, and then stirred by a known method as appropriate to obtain a coupling reaction with the copper powder and / or the oxide filler. Can be promoted. In a preferred embodiment, stirring can be performed, for example, at room temperature, for example, at temperatures in the range of 5-80 ° C, 10-40 ° C, 20-30 ° C. Further, stirring is preferably carried out for 1 minute or longer, more preferably 30 minutes or longer, in order to promote the coupling reaction between the copper powder and / or the oxide filler and the coupling agent.

The concentration of the coupling agent in the aqueous solution of the coupling agent is preferably 10% by volume or more, more preferably 20% by volume or more in order to promote the self-condensation reaction. Further, the concentration of the coupling agent in the aqueous solution of the coupling agent is preferably 60% by volume or less, preferably 45% by volume or less in order to prevent the self-condensation reaction from progressing excessively and gelling. Is more preferable.

In certain embodiments, stirring may be performed by sonication. The treatment time of the ultrasonic treatment is selected depending on the state of the dispersion liquid, but is preferably 1 to 180 minutes, more preferably 3 to 150 minutes, still more preferably 10 to 120 minutes, and most preferably 20 to 80 minutes. Can be. In a preferred embodiment, the sonication can be carried out at an output of preferably 50-600 W, more preferably 100-600 W per 100 mL. In a preferred embodiment, the sonication can be carried out at a frequency of preferably 10 to 1 MHz, more preferably 20 to 1 MHz, even more preferably 50 to 1 MHz.

After the surface treatment with the coupling agent, the surface-treated copper powder and / or the oxide filler can be separated and recovered from the copper powder and / or the oxide filler dispersion liquid. Known means can be used for this separation / recovery, and for example, filtration, centrifugation, decantation, or the like can be used.

Known means can be used for drying the cake after separation and recovery, and for example, drying by heating can be performed. The heat drying can be performed, for example, by heat treatment at a temperature of 50 to 400 ° C. and 60 to 350 ° C. for, for example, 5 to 180 minutes and 30 to 120 minutes. Following the heat drying, the copper powder and / or the oxidized filler may be further crushed, if desired. Further, for the recovered surface-treated copper powder and / or oxide filler, copper having an organic substance or the like further surface-treated for the purpose of preventing rust or improving dispersibility in the paste. It may be adsorbed on the surface of the powder and / or the oxide filler.

In a preferred embodiment, the surface-treated copper powder and / or the oxide filler may be further surface-treated after being surface-treated with a coupling agent. As such a surface treatment, for example, a rust preventive treatment with an organic rust preventive agent such as benzotriazole or imidazole can be mentioned, and even by such a normal treatment, the surface treatment layer with a coupling agent is desorbed or the like. There is no such thing. Therefore, those skilled in the art can optionally perform such known surface treatments to the extent that excellent sintering delay is not lost. That is, the copper powder and / or the oxide filler obtained by further surface-treating the surface of the surface-treated copper powder and / or the oxide filler according to the present disclosure within the limit of not losing the excellent sintering delay property. Is also within the scope of this disclosure.

[Binder resin]
Examples of the binder resin used in the conductive composition include cellulose-based resin, acrylic resin, alkyd resin, polyvinyl alcohol-based resin, polyvinyl acetal, ketone resin, urea resin, melamine resin, polyester, polyamide, and polyurethane. can. One type of binder resin may be used alone, or two or more types may be used in combination. The binder resin in the conductive composition can be contained in a ratio of, for example, 0.1 to 10%, preferably 1 to 8%, based on the mass of the copper powder. By setting the blending ratio of the binder resin within the above range, the structural stability and uniform coating property of the conductive composition can be improved.

[Dispersion medium]
As the dispersion medium used in the conductive composition, for example, one or more selected from the group consisting of alcohol solvents (for example, terpineol, dihydroterpineol, isopropyl alcohol, butyl carbitol, terpineloxyethanol, dihydroterpineloxyethanol). ), Glycol ether solvent (eg butyl carbitol), acetate solvent (eg butyl carbitol acetate, dihydro turpineol acetate, dihydro carbitol acetate, carbitol acetate, linaryl acetate, turpinyl acetate 1) Species or more), ketone solvent (for example, methyl ethyl ketone), hydrocarbon solvent (for example, one or more selected from the group consisting of toluene and cyclohexane), cellosolves (for example, one or more selected from the group consisting of ethyl cellosolve and butyl cellosolve). , Diethylphthalate, or a propineauto solvent (for example, one or more selected from the group consisting of dihydroterpinyl propine auto, dihydrocarbyl propine auto, and isovonyl propine auto). One type of dispersion medium may be used alone, or two or more types may be used in combination. The conductive composition may contain a dispersion medium at a ratio of, for example, 10 to 400% with respect to the mass of the copper powder.

[Other additives]
The conductive composition according to the present disclosure may appropriately contain known additives such as glass frit, dispersant, thickener and defoamer.

Glass frit is useful for improving the adhesion between the ceramic and the conductor. As the glass frit, for example, a glass frit having a BET specific surface area of 1 to 10 m ² g ^-1 , preferably 2 to 10 m ² g ^-1 , and more preferably 2 to 8 m ² g ^-1 can be used. The conductive composition may contain glass frit at a ratio of, for example, 0 to 5% with respect to the mass of the copper powder.

Examples of the dispersant include oleic acid, stearic acid and oleylamine. The conductive composition may contain a dispersant at a ratio of, for example, 0 to 5% with respect to the mass of the copper powder.

Examples of the defoaming agent include organically modified polysiloxane and polyacrylate. The conductive composition may contain an antifoaming agent at a ratio of, for example, 0 to 5% with respect to the mass of the copper powder.

The ratio of the copper powder, the oxide filler, the binder resin, and the dispersion medium in the conductive composition may be appropriately determined within a range that does not impair the coatability according to the use of the conductive composition.

The present disclosure will be described in more detail with reference to examples below. The present disclosure is not limited to the following examples.

(Procedure 1: Copper powder of Examples 1 to 4, Comparative Examples 1 and 2)
6 L of pure water was added to a 50 L container and heated so that the liquid temperature became 70 ° C. 3.49 kg of copper sulfate pentahydrate was added thereto, and it was visually confirmed that all the crystals of copper sulfate were dissolved while stirring at 350 rpm. To this, 1.39 kg of D-glucose was added. A 5 wt% aqueous ammonia solution was added thereto by a liquid feed pump at a rate of 300 mL / min until pH 5 was reached. When the pH reached 5, an aqueous ammonia solution was added dropwise with a dropper to raise the pH to 8.4. From here, the liquid temperature was maintained at 70 ± 2 ° C. and pH 8.5 ± 0.1 for 3 hours. The pH was adjusted with an aqueous ammonia solution. After completion of the reaction, decantation, discharge of the supernatant, and washing with pure water were repeated until the pH of the supernatant was below 8.0 to obtain a cuprous oxide powder slurry. A part of the solid content was taken out and dried in nitrogen at 70 ° C., and it was confirmed by XRD that this solid content was cuprous oxide.

The water content of the cuprous oxide powder slurry obtained above was adjusted to 20% by mass, and pure water (25) was added to the cuprous oxide powder slurry (25 ° C.) so that the water content was 7 L per 1 kg of solid content. ° C.) was added, 4 g of Nikawa was further added, and the mixture was stirred at 500 rpm. To this, 2 L (25 ° C.) of dilute sulfuric acid of 25 vol% was instantaneously added to adjust the pH to 0.7. The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the Cu concentration derived from Cu ²⁺ in the supernatant was less than 1 g / L. Then, it was put into 3L of ammonia water prepared to pH 13, and stirred. Stirring was performed at 25 ° C. for 1 hour. Then, solid-liquid separation was performed by suction filtration to obtain a pH-treated copper powder cake. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill.

(Procedure 2: Measurement of bulk density)
The bulk density of the obtained copper powder was measured by the method described above using Powder Tester PT-X manufactured by Hosokawa Micron Co., Ltd.

(Procedure 3: Measurement of BET specific surface area)
The BET specific surface area of the obtained copper powder was measured after pretreatment by heating at 200 ° C. for 5 hours in vacuum using BELSORP-miniII manufactured by Microtrac Bell.

(Procedure 4: Examples 1 to 6 (However, Example 6 is a reference example) , 10 to 13 , 15, and the cuprous oxide powder of Comparative Examples 1 to 3)
6 L of pure water and 9 g of gum arabic were added to a 50 L container and heated so that the liquid temperature became 70 ° C. 3.49 kg of copper sulfate pentahydrate was added thereto, and it was visually confirmed that all the crystals of copper sulfate were dissolved while stirring at 350 rpm. To this, 1.39 kg of D-glucose was added. A 5 wt% aqueous ammonia solution was added thereto by a liquid feed pump at a rate of 300 mL / min until pH 5 was reached. When the pH reached 5, an aqueous ammonia solution was added dropwise with a dropper to raise the pH to 8.4. From here, the liquid temperature was maintained at 70 ± 2 ° C. and pH 8.5 ± 0.1 for 3 hours. The pH was adjusted with an aqueous ammonia solution. After completion of the reaction, decantation, discharge of the supernatant, and washing with pure water were repeated until the pH of the supernatant was below 8.0. Then, the cake was obtained by solid-liquid separation by suction filtration. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The obtained powder was confirmed to be cuprous oxide powder by XRD. The bulk density and BET specific surface area were determined according to the procedures of Step 2 and Step 3.

(Procedure 5: Surface-treated copper powder of Examples 9 to 11 and 14 to 16)
Dilute sulfuric acid was instantaneously added to the cuprous oxide powder slurry (25 ° C.) prepared in step 1. The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the pH of the supernatant exceeded 4. An appropriate amount of the supernatant was removed to obtain a copper powder slurry having a water content of 20% by mass. Further, as a coupling agent, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) (hereinafter referred to as "diaminosilane") was prepared. This coupling agent and pure water were mixed, and the pH was further adjusted to 12.5 with aqueous ammonia to obtain an aqueous coupling agent solution. The concentration of diaminosilane in the aqueous coupling agent solution was 15 wt%. This was stirred at 25 ° C. for 14 hours to promote the self-condensation reaction of the coupling agent. Next, the pretreated aqueous solution and 550 g of the copper powder slurry having a water content of 20% by mass were mixed and stirred at 25 ° C. and 500 rpm for 1 hour. Then, solid-liquid separation was performed by suction filtration, and the copper powder was recovered as cakes having different water content according to the test number. The amount of Si adhered was adjusted by increasing or decreasing the water content of the cake after solid-liquid separation. The higher the water content of the cake, the greater the amount of Si attached to the copper powder. The obtained cake was dried at 100 ° C. for 2 hours under a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 6: Surface-treated cuprous oxide powder of Examples 9 and 14)
Pure water was added to the cuprous oxide powder cake washed with the pure water obtained in step 4 to prepare a cuprous oxide powder slurry having a water content of 20% by mass. Further, as a coupling agent, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) (hereinafter referred to as "diaminosilane") was prepared. This coupling agent and pure water were mixed, and the pH was further adjusted to 12.5 with aqueous ammonia to obtain an aqueous coupling agent solution. The concentration of diaminosilane in the aqueous coupling agent solution was 15 wt%. This was stirred at 25 ° C. for 14 hours to promote the self-condensation reaction of the coupling agent. Next, 1250 g of the cuprous oxide powder slurry having a water content of 20% by mass was mixed with the aqueous solution that had undergone this pretreatment, and the mixture was stirred at 25 ° C. and 500 rpm for 1 hour. Then, the cake of cuprous oxide powder was recovered by solid-liquid separation by suction filtration. The obtained cake was dried at 100 ° C. for 2 hours under a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The BET specific surface area was determined according to the same procedure as in step 3.

(Procedure 7: Copper powder of Example 5)
Dilute sulfuric acid was instantaneously added to the cuprous oxide powder slurry (25 ° C.) prepared in step 1. The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the Cu concentration derived from Cu ²⁺ in the supernatant was less than 1 g / L. Then, it was put into 3L of ammonia water adjusted to pH 8 and stirred. Stirring was performed at 25 ° C. for 1 hour. Then, solid-liquid separation was performed by suction filtration to obtain a pH-treated copper powder cake. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 8: Copper powder of Example 6 (reference example) )
Dilute sulfuric acid was instantaneously added to the cuprous oxide powder slurry (25 ° C.) prepared in step 1. The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the pH of the supernatant reached 7. Then, solid-liquid separation was performed by suction filtration, and the obtained cake was dried at 100 ° C. for 2 hours under a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 9: Copper powder of Example 7)
In step 1, a collagen peptide having a molecular weight of 5000 was used instead of glue, and dilute sulfuric acid was instantaneously added to the cuprous oxide powder slurry (25 ° C.). The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the Cu concentration derived from Cu ²⁺ in the supernatant was less than 1 g / L. Then, it was put into 3L of ammonia water adjusted to pH 13 and stirred. Stirring was performed at 25 ° C. for 1 hour. Then, solid-liquid separation was performed by suction filtration to obtain a pH-treated copper powder cake. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 10: Copper powder of Example 8)
In step 1, dilute sulfuric acid was added to the cuprous oxide powder slurry (25 ° C.) at 50 mL / min. The decantation and washing operations were repeated until the Cu concentration derived from Cu ²⁺ in the supernatant was less than 1 g / L. Then, it was put into 3L of ammonia water adjusted to pH 13 and stirred. Stirring was performed at 25 ° C. for 1 hour. Then, solid-liquid separation was performed by suction filtration to obtain a pH-treated copper powder cake. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 11: Surface-treated copper powder of Example 12)
A surface-treated copper powder was prepared in the same procedure as in step 5 except that the coupling agent in step 5 was the following titanium aminoethylaminoethanolate (manufactured by Matsumoto Fine Chemical Co., Ltd., Organtics TC-510), and the surface-treated copper powder was prepared in steps 2 and 3. The bulk density and the BET specific surface area were determined according to the above.

(Procedure 12: Surface-treated copper powder of Example 13)
Same as step 5 except that the coupling agent of step 5 was changed to a mixed solution of diaminosilane and the following zirconium lactate ammonium salt (manufactured by Matsumoto Fine Chemical Co., Ltd., Olgatics ZC-300) at 70:30 (mass ratio). The surface-treated copper powder was prepared according to the above procedure, and the bulk density and the BET specific surface area were determined according to the procedures 2 and 3.

(Procedure 13: Copper powder of Comparative Example 3)
Dilute sulfuric acid was instantaneously added to the cuprous oxide powder slurry (25 ° C.) prepared in step 1. The powder was settled by decantation, the supernatant was drained, 7 L of pure water (25 ° C.) was added, and the mixture was stirred at 500 rpm for 10 minutes. The decantation and washing operations were repeated until the pH of the supernatant reached 7. Then, solid-liquid separation was performed by suction filtration, and the obtained cake was dried at 100 ° C. for 2 hours under a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.1 mm. The bulk density and BET specific surface area were determined according to the same procedure as in Step 2 and Step 3.

(Procedure 14: Copper oxide powder of Example 7)
6 L of pure water and 9 g of gum arabic were added to a 50 L container and heated so that the liquid temperature became 70 ° C. 3.49 kg of copper sulfate pentahydrate was added thereto, and it was visually confirmed that all the crystals of copper sulfate were dissolved while stirring at 350 rpm. To this, 1.39 kg of D-glucose was added. A 5 wt% aqueous ammonia solution was added thereto by a liquid feed pump at a rate of 300 mL / min until pH 5 was reached. When the pH reached 5, an aqueous ammonia solution was added dropwise with a dropper to raise the pH to 8.4. From here, the liquid temperature was maintained at 70 ± 2 ° C. and pH 8.5 ± 0.1 for 3 hours. The pH was adjusted with an aqueous ammonia solution. After completion of the reaction, decantation, discharge of the supernatant, and washing with pure water were repeated until the pH of the supernatant was below 8.0. Then, the cake was obtained by solid-liquid separation by suction filtration. The obtained cake was dispersed in an aqueous solution containing 6 L of pure water and 9 g of gum arabic in a 50 L container, and heated so that the liquid temperature became 70 ° C. 3.49 kg of copper sulfate pentahydrate was added thereto, and it was visually confirmed that all the crystals of copper sulfate were dissolved while stirring at 350 rpm. To this, 1.39 kg of D-glucose was added. A 5 wt% aqueous ammonia solution was added thereto by a liquid feed pump at a rate of 300 mL / min until pH 5 was reached. When the pH reached 5, an aqueous ammonia solution was added dropwise with a dropper to raise the pH to 8.4. From here, the liquid temperature was maintained at 70 ± 2 ° C. and pH 8.5 ± 0.1 for 3 hours. The pH was adjusted with an aqueous ammonia solution. After completion of the reaction, decantation, discharge of the supernatant, and washing with pure water were repeated until the pH of the supernatant was below 8.0. Then, the cake was obtained by solid-liquid separation by suction filtration. The obtained cake was washed with pure water with the pH of the pure water after filtration as a guideline of less than 8. The washing cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. The obtained powder was confirmed to be cuprous oxide powder by XRD. The BET specific surface area was determined according to the same procedure as in step 3.

(Procedure 15: Copper oxide powder of Example 8)
A cuprous oxide powder was prepared according to the procedure 4 except that gum arabic was used as a collagen peptide having a molecular weight of 5000 in the procedure 4. The BET specific surface area was determined according to the same procedure as in step 3.

(Procedure 16: Copper oxide powder of Example 16)
A cuprous oxide powder slurry was prepared according to step 4, and washed until the pH fell below 8. Then, pure water was added so as to have a solid content of 20% by mass, the mixture was heated to 40 ° C., and stirred for 2 hours at 300 rpm. Then, the cake was obtained by solid-liquid separation by suction filtration. The cake was dried at 100 ° C. for 2 hours in a nitrogen atmosphere. The obtained dry powder was crushed in a mortar and pestle until it passed through a sieve having a hole of 0.7 mm, and further crushed by a jet mill. It was confirmed by XRD that the obtained powder was copper oxide powder. The BET specific surface area was determined according to the same procedure as in Step 2 and Step 3.

(Procedure 17: Amount of metal adhered from the coupling agent in the surface treatment powder)
The surface-treated copper powder, the surface-treated cuprous oxide powder, and the surface-treated copper oxide powder (hereinafter referred to as "surface-treated copper powder") obtained in the above procedure of Examples and Comparative Examples are dissolved with an acid to emit light from ICP. The mass (μg) of attached Si, Ti, and Zr with respect to the unit mass (g) of the surface-treated powder was determined by a spectroscopic analysis method (ICP-OES manufactured by Hitachi High-Tech Science Co., Ltd.). The results are shown in Table 1. The table does not describe the element concentration below the lower limit of detection.

(Procedure 18: Paste preparation)
A vehicle was prepared by thoroughly kneading terpineol and ethyl cellulose through a rotating revolution mixer AR-100 and three rolls in advance. Next, various copper powders, cuprous oxide powders, and copper oxide powders prepared in steps 1 to 16 were mixed according to the oxide filler / (copper powder + oxide filler) ratio in the table. The powder after this mixing is referred to as an inorganic powder. Inorganic powder: Ethyl cellulose: Oleic acid: Terpineol = 80: 2.3: 1.6: 16.1 (weight ratio), pre-kneaded with a rotating revolution mixer, and then passed through 3 rolls (finishing). Roll gap 5 μm), defoaming using a rotation / revolution mixer to prepare each paste of Example (excluding Example 15) and Comparative Example.
For Example 15, an inorganic powder obtained by mixing the surface-treated copper powder prepared in step 5 and the sub-copper oxide powder prepared in step 4 at the oxide filler / (copper powder + oxide filler) ratio shown in Table 1 was used. , Inorganic powder: Ethyl cellulose: Tarpineol = 35: 1.8: 63.2 (weight ratio) A paste was prepared according to the same procedure as above.

(Procedure 19: Surface roughness (Ra) of the paste coating film)
Each of the pastes of Examples and Comparative Examples obtained in the above procedure was applied onto a slide glass at a moving speed of 5 cm / sec using an applicator with a 25 μm gap, and dried at 120 ° C. for 10 minutes. Ra (JIS B0633: 2001 compliant) in the coating direction of the obtained coating film was measured at 5 points with a stylus type roughness meter, and the average value was taken as the measured value. The results are shown in Table 1.

(Procedure 20: XRD of paste coating film)
The paste prepared in step 19 was applied onto a slide glass at a moving speed of 5 cm / sec using an applicator with a 25 μm gap, and dried at 120 ° C. for 10 minutes to obtain a dry coating film. XRD measurement was performed on this dry coating film under the following conditions, the peak area of (111) of cuprous oxide, copper oxide, and copper was calculated, and Cu ₂ O (111) / Cu (111) or CuO (111) / Cu (111) was determined. When both cuprous oxide powder and copper oxide powder are used as the oxide filler, {Cu ₂ O (111) + CuO (111)} / Cu (111) is obtained.
The background processing for calculating the peak area was performed by the automatic processing mode of the integrated powder X-ray analysis software PDXL2 manufactured by RIGAKU. By selecting this mode, the software performs a simple peak search, removes the peak portion, and then fits a polynomial to the rest of the data to remove the background.
Equipment: Rint 2200 Ultima (manufactured by RIGAKU)
X-ray: CuKα
X-ray output: 40kV, 40mA
Scan speed: 4 ° / min Step width: 0.02 °
Scan range: 20-80 °
Divergence slit: 2 °
Divergence vertical limiting slit: 10 mm
Scattering slit: 2 °
Light emitting slit: 0.6 mm
Peak area calculation software: PDXL2

(Procedure 21: Steam firing of paste)
The dry coating film obtained in step 20 is peeled off from the slide glass, sufficiently crushed with a pestle and a mortar, and 0.5 g of the obtained powder is hand-pressed using a mold having an inner diameter of φ5 mm to 4.7 ± 0. A columnar green compact having a density of 2 gcm ^-3 was formed. This green compact is removed from the mold, loaded into a thermomechanical analyzer (TMA4000 (Netch Japan)) so that the central axis is in the vertical direction, and the total pressure is 1 atm with a steam generator (HC9800 (Netch Japan)). , Nitrogen gas with a partial pressure of water vapor of 0.05 atm is flowed at 100 mL / min (22 ° C conversion), and the temperature rises from 20 ° C at a rate of 1 ° C / min while applying a load of 98 mN to the upper and lower surfaces of the green compact. Then, the volume shrinkage was determined from the height shrinkage of the green compact at 650 ° C. Shrinkage of the green compact represents combustion, decomposition and sintering of copper powder of the binder resin. The results are shown in Table 1.

(Procedure 22: resistivity of sintered body)
Using the pastes and screen plates (stainless mesh, wire diameter 18 μm, gauze thickness 38 μm, opening 33 μm, aperture ratio 42%) of the examples and comparative examples obtained in the above procedure, a green sheet (GCS71 manufactured by Yamamura Photonics). Three lines having a width of 5 mm and a length of 20 mm were printed on the surface. While supplying the remaining nitrogen gas having a total pressure of 1 atm and a steam partial pressure of 0.03 atm at 2 L / min, the temperature was raised to 850 ° C. at a rate of 0.75 ° C./min and maintained at 850 ° C. for 20 minutes. Then, it was cooled to room temperature at a rate of 5 ° C./min in a pure nitrogen atmosphere containing no water vapor. In this way, the sintered body of the paste was formed on the ceramic substrate to obtain a sintered body / ceramic laminate. The surface resistivity and thickness of the circuit having a width of 5 mm and a length of 20 mm obtained by cooling to room temperature were measured, and the specific resistance was obtained by averaging three points. The results are shown in Table 1.

(Procedure 23: Tape peeling test)
After attaching carbon double-sided tape (manufactured by Nissin EM) to the circuit and substrate obtained by the above procedure, the tape peeling test was performed at a peeling angle of 90 ° and a peeling speed of 5 mm / s according to JIS Z 0237: 2009. , It was confirmed that the circuit did not adhere to the adhesive surface of the tape. When at least a part of the circuit (sintered body) was peeled off from the substrate in one peeling test, it was judged as ×, when it was peeled off in two or three times, it was judged as Δ, and when it was peeled off in four or more times, it was judged as ○.

(Procedure 24: Analysis of metal concentration derived from coupling agent in sintered body)
Each of the pastes of Examples and Comparative Examples obtained in the above procedure was heated to 850 ° C. at a residual nitrogen atmosphere of 1 atm of total pressure and 0.03 atm of water vapor partial pressure at a heating rate of 1 ° C./min, and at 850 ° C. It was fired for 30 minutes and then cooled to room temperature at a rate of 10 ° C./min to obtain a sintered body. This sintered body was dissolved with an acid, and the concentrations of Si, Ti, and Zr in the sintered body were analyzed by ICP emission spectroscopy (ICP-OES manufactured by Hitachi High-Tech Science Co., Ltd.). The results are shown in Table 1. The table does not describe the element concentration below the lower limit of detection.

[Discussion]
Examples 1 to 1 in which the compounding ratio (peak area ratio) of the copper powder and the oxide filler (copper oxide and / or copper oxide), the surface roughness (Ra) of the coating film, and the volume resistivity at the time of firing were appropriate. When the paste of 16 was used, a conductor-ceramic laminate having a small resistivity of the conductor and excellent adhesion between the conductors was obtained even when firing in a steam atmosphere.
On the other hand, in Comparative Example 1, the specific resistance became large because the compounding ratio of the oxide filler was too high.
In Comparative Example 2, since the compounding ratio of the oxide filler was too low, the sintering delay property was insufficient, and the adhesion between the ceramic and the conductor was insufficient.
In Comparative Example 3, since the bulk density of the copper powder used was too high, the surface roughness of the coating film became large, and the adhesion between the ceramic and the conductor was insufficient.

Claims (11)

A conductive composition comprising copper powder, one or both oxidation fillers selected from the group consisting of cuprous oxide powder and copper oxide powder, a binder resin, and a dispersion medium.
The conductive composition is applied onto a slide glass at a moving speed of 5 cm / sec using an applicator with a 25 μm gap, dried at 120 ° C. for 10 minutes, and then coated with a stylus type roughness meter. Arithmetic mean roughness Ra in the direction is 0. It is less than 1 μm and
In the XRD of the coating film, the ratio of the peak area corresponding to the oxide filler on the (111) plane to the peak area corresponding to the copper powder on the (111) plane was 0.05 to 0.5.
From 0.5 g of powder obtained by crushing the coating film, a columnar green compact having a density of 4.7 ± 0.2 gcm ^-3 and a diameter of 5 mm was formed, and a load of 98 mN was applied to the green compact. The volume shrinkage at 650 ° C. is 15% or less when TMA is measured at a temperature rise rate of 1 ° C./min in a residual nitrogen atmosphere with a total pressure of 1 atm and a partial pressure of water vapor of 0.05 atm while being applied to the upper bottom surface.
Conductive composition. A sintered body obtained by heating the conductive composition to 850 ° C. at a heating rate of 1 ° C./min at a residual nitrogen atmosphere with a total pressure of 1 atm and a partial pressure of water vapor of 0.03 atm, and firing at 850 ° C. for 30 minutes. The conductive composition according to claim 1, wherein the total concentration of Si, Ti, Al and Zr is 1000 to 10000 mass ppm when measured by ICP emission spectroscopic analysis method. A sintered body obtained by heating the conductive composition to a total pressure of 1 atm, a residual nitrogen atmosphere of a water vapor partial pressure of 0.03 atm, a rate of 0.75 ° C./min to 850 ° C., and firing at 850 ° C. for 20 minutes. The conductive composition according to claim 1 or 2, wherein the specific resistance of the above is 3.0 μΩ · cm or less. The conductive composition according to any one of claims 1 to 3, wherein the copper powder and / or the oxide filler is surface-treated with a coupling agent. A copper powder having a compact bulk density of 3.0 g / cm ³ or less, one or both oxide fillers selected from the group consisting of cuprous oxide powder and copper oxide powder, a binder resin, and a dispersion medium are kneaded. The method for producing a conductive composition according to any one of claims 1 to 4, which comprises the above. The method for producing a conductive composition according to claim 5, wherein the copper powder has a bulk density of 2.5 g / cm ³ or less. The production method according to claim 5 or 6, wherein the ratio of the BET specific surface area of the oxide filler to the BET specific surface area of the copper powder is 0.2 to 3.0. The production method according to any one of claims 5 to 7, wherein the ratio of the mass of the oxide filler to the total mass of the copper powder and the oxide filler is 0.05 to 0.35. A method for producing a composite of a ceramic and a conductor, which comprises using the conductive composition according to any one of claims 1 to 4. A method for manufacturing a laminated ceramic capacitor, which comprises using the conductive composition according to any one of claims 1 to 4. A method for manufacturing a ceramic circuit board, which comprises using the conductive composition according to any one of claims 1 to 4.