TWI547325B - A surface-treated metal powder, and a method for producing the same - Google Patents

Description

Surface treated metal powder, and method of producing the same

The present invention relates to a surface-treated copper powder suitable for producing an electrode for a wafer-laminated ceramic capacitor, and a method of manufacturing the same.

Wafer-layered ceramic capacitors are characterized by their small size and large capacity, and are therefore electronic components used in many electronic devices. The wafer-stacked ceramic capacitor has a structure in which a ceramic dielectric body and an internal electrode are stacked in a layered manner, and each layer of the laminated layer constitutes a capacitor element, and the elements are electrically connected in parallel by external electrodes. Thus, the whole becomes a small and large-capacity capacitor.

In the manufacture of a wafer-stacked ceramic capacitor, a sheet of a dielectric is manufactured in the following manner. In other words, first, an organic binder and a solvent as a dispersing agent or a forming aid are added to a dielectric raw material powder such as BaTiO ₃ , and a slurry is obtained by a pulverization, mixing, and defoaming step. Thereafter, the slurry is applied to the carrier film such as a PET film by a coating method such as a film coater so as to be thinly spread. It was dried to obtain a thin dielectric sheet (green sheet).

On the other hand, the metal powder which is the internal electrode raw material of the wafer laminated ceramic capacitor is formed into a slurry by mixing and defoaming steps with an organic binder and a solvent as a dispersing agent or a forming aid, similarly to the dielectric raw material powder. material. The internal electrode is printed on the green sheet (dielectric sheet) mainly by screen printing, and after drying, the printed green sheet is peeled off from the carrier film, and a plurality of such green sheets are laminated.

The green sheets laminated in the above manner are applied to a green sheet having a pressure of 10 to several 100 MPa, and are formed into a single wafer. Thereafter, the internal electrode layer and the dielectric layer are sintered at a high temperature of about 1000 ° C in a firing furnace. Thus, a wafer-stacked ceramic capacitor can be manufactured.

At the time of development of the technology, Pt was used in the internal electrodes of such a wafer-stacked ceramic capacitor, but from the viewpoint of cost, Pd and Pd-Ag alloys were mainly used, and Ni was mainly used at present. However, in recent years, in terms of environmental control, it has been gradually required to replace Ni with Cu. Moreover, if Ni is replaced by Cu, in principle, low inductance can be achieved in high frequency applications. Also, Cu has the advantage of being lower in cost than Ni.

On the other hand, as the capacitor is miniaturized, the internal electrode tends to be thinned, and it is considered that the next-generation type internal electrode will be about 1 μm. Therefore, it is expected that the particle size of the powder for internal electrodes is smaller.

However, the melting point of the original Cu is already lower than Pt, Pd, and Ni. Further, the melting point caused by the increase in surface area due to the small diameter reduction of the particles as expected is such that when Cu is used as the internal electrode powder, the Cu powder starts to melt at a lower temperature at the time of firing. This condition causes cracks in the electrode layer itself. Further, since the electrode layer is rapidly contracted after the temperature is lowered, there is a possibility that the dielectric layer and the electrode layer are peeled off (layered). In order to avoid such a problem, the metal powder for internal electrodes is required to have heat shrinkage characteristics equivalent to those of the dielectric material, and as an index indicating the heat shrinkage characteristics, there is a sintering start temperature.

In response to the above requirements, a method of surface-treating Cu powder in order to obtain Cu powder suitable for an internal electrode of a wafer-stacked ceramic capacitor has been proposed.

Patent Document 1 (Japanese Patent No. 4001438) is a technique of making Cu The powder is dispersed in a liquid, an aqueous solution of a water-soluble salt of a metal element is added thereto, and the pH value is adjusted to fix the metal oxide on the surface of the Cu powder, thereby causing the surface-treated copper powder to collide with each other to strengthen the surface treatment layer. With. However, since the steps are composed of adsorption and fixation strengthening of the copper oxide by the metal oxide, there is a problem in terms of productivity. Further, it is expected that if the particle diameter of the copper powder is further less than 0.5 μm, the size of the adsorbed metal oxide particles is similar, and thus the adsorption of the copper powder by the oxide itself becomes difficult.

Patent Document 2 (Japanese Patent No. 4164009) is a technique of coating copper powder by a polyoxygenated oil having a specific functional group. However, since the oil is mixed with the Cu powder, it tends to aggregate, and there is a problem in workability. Further, when the oil is separated from the Cu powder, the filtration is difficult, and there is a problem in workability.

Patent Document 3 (Japanese Patent No. 3646259) is a technique in which a hydrolyzed alkoxysilane is subjected to condensation polymerization on an ammonia catalyst on a surface of a copper powder to form an SiO ₂ gel-coated film. However, when the technique is applied to copper powder having a particle diameter of 1 μm or less, it is necessary to continuously add NH ₃ as a catalyst to prevent aggregation, and the reaction control depends on the merits of the specific operation skill added, and thus it is very difficult in workability and production. There are problems with sex.

Patent Document 1: Japanese Patent No. 4001438

Patent Document 2: Japanese Patent No. 4164009

Patent Document 3: Japanese Patent No. 3646259

Thus, there is a need for a copper powder which is preferably used for producing an internal electrode of a wafer-laminated ceramic capacitor which is excellent in sintering retardation, workability, and productivity.

Accordingly, an object of the present invention is to provide a surface-treated copper powder which is preferably used for producing an electrode for a wafer-laminated ceramic capacitor and which is excellent in sintering retardation, and a method for producing the same.

The present inventors conducted intensive studies and found that by mixing copper powder with an aqueous solution of amino decane to adsorb the amino decane on the surface of the copper powder, there is no coagulation after surface treatment, and the sintering delay is remarkably improved. The present invention has been completed. This operation is very simple, requires no high level of skill, is excellent in workability, and is excellent in productivity. Further, the surface-treated copper powder obtained in the above manner exhibits a high sintering onset temperature although it is a small particle copper powder. Further, when the surface treatment of the metal powder other than the copper powder is performed in the same manner, and the surface treatment is performed by a coupling agent other than the amine decane, the surface-treated metal powder having the same excellent properties can be obtained. .

Therefore, the present invention is the following (1) to (27).

(1) A surface-treated copper powder in which a photoelectron of N is detected to be 1000 cps or more in a survey of XPS, and a photoelectron of Si is detected to be 1000 cps or more.

(2) A surface-treated copper powder having a surface N of 1% or more and a Si content of 0.6% or more detected in the Survey of XPS.

(3) The copper powder according to (1) or (2) above, wherein in the measurement of XPS, the surface N is detected to be 1% or more, and the photoelectron of N is detected to be 1000 cps (count per second) or more, and the detection is performed. The Si content was 0.6% or more, and the photoelectron of Si was detected to be 1000 cps or more.

(4) The copper powder according to any one of the above (1) to (3) wherein the copper powder is a copper powder surface-treated with a decane coupling agent.

(5) The copper powder according to (4) above, wherein the decane coupling agent is an amino decane.

(6) The copper powder according to any one of the above (1) to (5), which has a sintering start temperature of 400 ° C or higher.

(7) A copper powder obtained by heat-treating the copper powder according to any one of the above (1) to (6) to remove N.

(8) A copper powder obtained by heat-treating the copper powder according to any one of the above (1) to (7) in an oxygen atmosphere or an inert atmosphere.

(9) The copper powder according to any one of the above (1) to (8), which is obtained by mixing an aqueous solution of amino decane with copper powder, stirring it, and drying it.

(10) The copper powder according to any one of the above (1) to (9), wherein the amount of the amine decane to be surface-treated is 0.01 mL or more with respect to 1 g of the copper powder.

(11) The copper powder according to the above (10), wherein the amount of the amino decane is 0.05 mL or more, and the mixture is mixed with the copper powder, and the stirring time is 30 minutes or shorter.

(12) The copper powder according to any one of the above (5) to (11), wherein the amino decane is monoamino decane or diamino decane.

(13) The copper powder according to any one of (1) to (12) above, wherein the raw material copper powder is obtained by a wet method.

(14) The copper powder according to any one of the above (1) to (13), which has a D50 ≦ 1.5 μm.

(15) The copper powder according to any one of the above (1) to (13), which has a D50 ≦ 1.0 μm.

(16) The copper powder according to any one of (1) to (13) above which has a D50 ≦ 0.5 μm and a Dmax ≦ 1.0 μm.

(17) The copper powder according to any one of the above (1) to (16), wherein the particle size distribution is a single peak.

(18) A copper powder for internal electrodes, which is characterized by any one of the above (1) to (17).

(19) A copper powder for external electrodes, which is characterized by any one of the above (1) to (17).

(20) A surface-treated copper powder obtained by subjecting the copper powder according to any one of the above (1) to (19) to further surface treatment with an organic compound.

(21) A conductive paste using the copper powder according to any one of the above (1) to (20).

(22) A wafer laminated ceramic capacitor produced by using the paste of the above (21).

(23) The wafer multilayer ceramic capacitor according to the above (22), wherein SiO ₂ having a diameter of 10 nm or more exists in a cross section of the internal electrode.

(24) The wafer-layered ceramic capacitor according to the above (22) or (23), wherein SiO ₂ having a maximum diameter of 0.5 μm or more exists in a cross section of the internal electrode of 0.5/cm ² or less.

(25) A multilayer substrate in which the wafer laminated ceramic capacitor according to any one of the above (22) to (24) is attached to the outermost layer.

(26) A multilayer substrate in which the wafer laminated ceramic capacitor according to any one of the above (22) to (24) is laminated to an inner layer.

(27) An electronic component in which the multilayer substrate of the above (25) or (26) is mounted.

Further, the present invention is also the following (31) to (50).

(31) A method of producing a surface-treated copper powder comprising the steps of mixing a copper powder with an aqueous solution of an amino decane to prepare a copper powder dispersion.

(32) The method according to (31) above, which comprises the step of stirring the copper powder dispersion.

(33) A method according to (31) or (32) above, which comprises the step of ultrasonically treating the copper powder dispersion.

(34) The method of (33) above, wherein the step of performing the ultrasonic processing is a step of performing ultrasonic processing for 1 to 180 minutes.

(35) The method according to any one of the above (31) to (34), comprising the steps of: filtering a copper powder dispersion to recover copper powder; and drying the filtered copper powder to obtain a surface The step of treating the copper powder.

(36) The method according to (35) above, wherein the drying is carried out by heat treatment at 50 to 90 ° C for 30 to 120 minutes.

(37) The method according to the above (35) or (36), wherein the drying is carried out in an oxygen atmosphere or an inert environment.

The method of any one of the above (31) to (37), wherein the copper dispersion liquid phase contains 0.025 g or more of the amine decane for 1 g of the copper powder.

The method of any one of the above (31) to (38), wherein the aqueous solution of the amino decane is an aqueous solution of the amino decane represented by the following formula I: H ₂ NR ¹ -Si(OR ² ) ₂ ( R ³ ) (Formula I)

(In the above formula I, R1 is a linear or branched saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic C1~C12 A divalent group of a hydrocarbon, R2 is an alkyl group of C1 to C5, and R3 is an alkyl group of C1 to C5 or an alkoxy group of C1 to C5.

(40) The method according to the above (39), wherein R1 is a group selected from the group consisting of a substituted or unsubstituted C1-C12 linear saturated hydrocarbon, a divalent group, a substituted or Divalent group of unsubstituted C1~C12 branched saturated hydrocarbon, divalent group of substituted or unsubstituted linear unsaturated hydrocarbon of C1~C12, substituted or unsubstituted C1~C12 branch a divalent group of a monounsaturated hydrocarbon, a divalent group of a substituted or unsubstituted C1 to C12 cyclic hydrocarbon, a divalent group of a substituted or unsubstituted C1 to C12 heterocyclic hydrocarbon, substituted or not A divalent group of an aromatic hydrocarbon substituted with C1 to C12.

(41) The method according to the above (39), wherein R1 is a group selected from the group consisting of -(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 ) _j - (wherein n, m, j are integers of 1 or more).

(42) The method according to the above (39), wherein R1 is -(CH ₂ ) _n - or -(CH ₂ ) _n -NH-(CH ₂ ) _m -.

(43) The method of (41) or (42) above, wherein n, m, and j are each independently 1, 2 or 3.

The method of any one of the above (39) to (43), wherein R2 is a methyl group or an ethyl group.

The method of any one of the above (39) to (44), wherein R3 is a methyl group, an ethyl group, a methoxy group or an ethoxy group.

(46) The method according to any one of the above (31) to (45) wherein the copper powder is copper powder produced by a wet method.

(47) A method of producing a conductive copper paste by blending a surface-treated copper powder produced by the production method according to any one of the above (31) to (46) with a solvent and/or a binder A conductive copper paste is produced.

(48) A method of producing an electrode, comprising the step of blending a surface-treated copper powder produced by the production method according to any one of the above (31) to (46) with a solvent and/or a binder a step of obtaining a conductive copper paste; a step of applying a conductive copper paste to the substrate; and a step of heating and baking the conductive copper paste applied to the substrate.

(49) The method according to (48) above, wherein the electrode is an electrode for a wafer laminated ceramic capacitor.

(50) The method according to any one of (31) to (49) above comprising the step of surface-treating the surface-treated copper powder further by an organic compound.

Further, the present invention is also the following (51) to (54).

(51) A surface-treated copper powder produced by the production method according to any one of the above (31) to (46).

(52) A conductive copper paste produced by the production method of the above (45).

(53) An electrode produced by the production method of the above (46).

(54) An electrode for a wafer laminated ceramic capacitor produced by the method of the above (47).

Further, the present invention is also the following (61) to (63).

(61) A copper powder obtained by the surface-treated copper powder produced by the method of any one of the above (31) to (46), wherein a surface N of 1% is detected in a survey of XPS As described above, the photoelectron of N is 1000 cps (count per second), and Si is 0.6% or more, the photoelectron of Si is 1000 cps or more, and the sintering start temperature is 400 ° C or more.

(62) A conductive copper paste obtained by blending the surface-treated copper powder of the above (61).

(63) An electrode obtained by applying the conductive copper paste of the above (62) and firing it by heating; and having SiO ₂ having a maximum diameter of 0.5 μm or more in an electrode cross section of 0.5/cm ² or less .

Further, the present invention is also the following (71) to (78).

(71) A surface-treated metal powder having a surface N of 1% or more detected in a survey of XPS, and detecting any one or more of Ti, Al, Si, Zr, Ce, and Sn is 0.6% the above.

(72) The metal powder according to (71) above, wherein the metal powder is any one of Cu, Pt, Pd, Ag, and Ni.

(73) The metal powder according to (71) or (72) above, wherein Ti, Al, Si, Zr, Ce, and Sn are adsorbed by the treatment with a coupling agent.

(74) The metal powder according to (73) above, wherein the coupling agent is any one of decane, titanate, and aluminate.

(75) The metal powder according to (74) above, which is treated by a coupling agent having an amine group at the end.

(76) A metal powder having a surface N of 1% or more and a Ti, Al, Si, Zr, Ce, and Sn of 0.6% or more and a sintering start temperature of 400 ° C or more in the measurement of XPS.

(77) A conductive copper paste obtained by blending the surface-treated metal powder of any one of the above (71) to (76).

(78) An electrode obtained by applying the conductive copper paste of the above (77) and firing it by heating; and having SiO ₂ having a maximum diameter of 0.5 μm or more in an electrode cross section of 0.5/μm ² or less , TiO ₂ , Al ₂ O ₃ .

Further, the present invention is also the following (101) to (143).

(101) A surface-treated metal powder, wherein in the survey of XPS, the photoelectron of N is detected to be 1000 cps (count per second) or more, and any one of Ti, Al, Si, Zr, Ce, and Sn is detected. The photoelectron is above 1000 cps.

(102) A surface-treated metal powder having a surface N of 1% or more detected in a survey of XPS, and detecting any one or more of Ti, Al, Si, Zr, Ce, and Sn is 0.6% the above.

(103) The surface-treated metal powder according to (101) or (102) above, wherein in the measurement of XPS, the surface N is detected to be 1% or more, and Si, Ti or Al is detected to be 0.6% or more. .

(104) The metal powder according to any one of the above (101) to (103), wherein in the measurement of XPS, the surface N is detected to be 1% or more, and the photoelectron of N is detected to be 1000 cps (count per second) As described above, Si or Ti was detected to be 0.6% or more, and photoelectrons of Si, Ti or Al were detected to be 1000 cps or more.

The metal powder according to any one of the above (101), wherein the metal powder is any one of Cu, Pt, Pd, Ag, and Ni.

The metal powder according to any one of the above (101), wherein the metal powder is copper powder.

(107) The metal powder according to any one of (101) to (106) above which is adsorbed with Ti, Al, Si, Zr, Ce, and Sn by a coupling agent treatment.

(108) The metal powder according to (107) above, wherein the coupling agent is any one of decane, titanate, and aluminate.

(109) A metal powder according to the above (108) which is treated with a coupling agent having an amine group at the end.

The metal powder according to any one of the above (101) to (109) wherein the metal powder is a metal powder surface-treated with a decane coupling agent.

(111) The metal powder according to (110) above, wherein the decane coupling agent is an amino decane.

(112) The metal powder according to any one of the above (101) to (111), which has a sintering start temperature of 400 ° C or higher.

(113) The metal powder according to (111) or (112) above, wherein the amino decane is monoamine decane or diamino decane.

(114) A surface-treated metal powder obtained by further surface-treating a metal powder according to any one of the above (101) to (113).

(115) A conductive metal powder paste using the metal powder according to any one of the above (101) to (114).

(116) A wafer laminated ceramic capacitor produced by using the paste of the above (115).

(104) The wafer-stacked ceramic capacitor according to the above (116), wherein SiO ₂ , TiO ₂ or Al ₂ O ₃ having a diameter of 10 nm or more is present in the internal electrode cross section.

(118) The wafer-stacked ceramic capacitor of the above (116) or (117), wherein SiO ₂ , TiO ₂ or Al ₂ O ₃ having a maximum diameter of 0.5 μm or more exists in a cross section of the internal electrode of 0.5/μm ² or less. .

(119) A multilayer substrate in which the wafer laminated ceramic capacitor according to any one of the above (116) to (118) is attached to the outermost layer.

(120) A multilayer substrate in which the wafer laminated ceramic capacitor according to any one of the above (116) to (118) is attached to the inner layer.

(121) An electronic component in which the multilayer substrate of the above (119) or (120) is mounted.

(122) A method of producing a surface-treated metal powder comprising the steps of mixing a metal powder with an aqueous solution of a coupling agent to prepare a metal powder dispersion.

(123) The method according to the above (122), wherein the metal powder is any one of Cu, Pt, Pd, Ag, and Ni.

(124) The method of (122) above, wherein the metal powder is copper powder.

(125) The method according to any one of the above (122) to (124), comprising the step of stirring the metal powder dispersion.

(126) The method according to any one of the above (122) to (125) comprising the step of ultrasonically treating the metal powder dispersion.

(127) The method of (126) above, wherein the step of performing the ultrasonic processing is a step of performing ultrasonic processing for 1 to 180 minutes.

The method of any one of the above (122) to (127), comprising the steps of: filtering the metal powder dispersion to recover the metal powder; and drying the filtered metal powder to obtain a surface. The step of treating the metal powder.

(129) The method of (128) above, wherein the drying is carried out in an oxygen atmosphere or an inert environment.

The method of any one of the above-mentioned (122) to (129), wherein the metal powder dispersion liquid phase contains 0.025 g or more of a coupling agent for 1 g of copper powder.

The method of any one of the above (122) to (130), wherein the aqueous solution of the coupling agent is an aqueous solution of an amino decane represented by the following formula I: H ₂ NR ¹ -Si(OR ² ) ₂ (R ³ ) (Formula I)

(In the above formula I, R1 is a linear or branched saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic C1~C12 a divalent group of a hydrocarbon, R2 is an alkyl group of C1 to C5; and R3 is an alkyl group of C1 to C5 or an alkoxy group of C1 to C5.

(132) The method according to the above (131), wherein R1 is a group selected from the group consisting of: -(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 ) _j - (wherein n, m, j are integers of 1 or more).

The method of any one of the above (122) to (130), wherein the aqueous solution of the coupling agent is an aqueous solution of an amine group-containing titanate represented by the following formula II: (H ₂ NR ¹ -O) _P Ti(OR ² ) _q (Formula II)

(In the above formula II, R1 is a linear or branched saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic C1~C12 a divalent group of a hydrocarbon, R2 is a linear or branched C1 to C5 alkyl group; p and q are integers of 1 to 3, and p+q=4).

(134) The method according to the above (133), wherein R1 is a group selected from the group consisting of -(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 ) _j - (wherein n, m, j are integers of 1 or more).

The method of any one of the above (122) to (134), wherein the metal powder is copper powder produced by a wet method.

(136) A method of producing a conductive metal powder paste by mixing the surface-treated metal powder produced by the production method according to any one of the above (122) to (135) with a solvent and/or a binder A conductive metal powder paste is produced in combination.

(137) A method of producing an electrode, comprising the step of blending a surface-treated metal powder produced by the production method according to any one of the above (122) to (135) with a solvent and/or a binder a step of obtaining a conductive metal powder paste; a step of applying a conductive metal powder paste to the substrate; and a step of heating and baking the conductive metal powder paste applied to the substrate.

(138) A surface-treated metal powder produced by the production method according to any one of the above (122) to (135).

(139) A conductive metal powder paste produced by the production method of the above (136).

(140) An electrode produced by the production method of the above (137).

(141) A metal powder which is a surface-treated metal powder produced by the method of any one of (122) to (135) above; in the survey of XPS, a surface N of 1% is detected. Above, the photoelectron of N is 1000 cps (count per second), and Si, Ti or Al is 0.6% or more, and the light of Si, Ti or Al The electrons are 1000 cps or more, and the sintering start temperature is 400 ° C or more.

(142) A conductive metal powder paste obtained by blending the surface-treated metal powder of the above (141).

(143) An electrode obtained by applying the conductive metal powder paste of the above (142) and firing it by heating; and having SiO having a maximum diameter of 0.5 μm or more in an electrode cross section of 0.5/μm ² or less ₂ , TiO ₂ or Al ₂ O ₃ .

The surface-treated copper powder of the present invention does not aggregate after surface treatment, and is excellent in sintering retardation, and even a small particle copper powder exhibits a high sintering onset temperature. Therefore, when a conductive copper paste obtained by blending the surface-treated copper powder of the present invention is used, it is possible to avoid problems in manufacturing such as electrode peeling, and it is advantageous to manufacture an electrode for a wafer laminated ceramic capacitor. Further, the surface-treated copper powder of the present invention can be produced by very simple treatment of copper powder, and the manufacturing method does not require a high degree of skill, and is excellent in workability and productivity. Further, according to the present invention, the metal powder other than the copper powder can have the same excellent characteristics.

Figure 1 is a TEM image of a cross section of a sintered body obtained from surface-treated copper powder.

Fig. 2 is a graph showing the results of XPS survey of the surface of the surface-treated copper powder (Example).

Fig. 3 is a graph showing the results of XPS survey of the surface of the surface-treated copper powder (Comparative Example).

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

In the present invention, a step of preparing a copper powder dispersion by mixing copper powder with an aqueous solution of an amino decane, and obtaining a surface-treated copper powder from the copper powder dispersion may be carried out.

As the copper powder for surface treatment, copper powder produced by a known method can be used. For example, the copper powder may be any of copper powder produced by a dry method or copper powder produced by a wet method. As far as the surface treatment of the present invention is consistently a wet process, copper powder produced by a wet process is preferred.

The aqueous solution of amino decane is an aqueous solution of an amino decane which can be used as a decane coupling agent. In a preferred embodiment, the amount of the amino decane used may be set to be 0.025 g or more, preferably 0.050 g, based on 1 g of the mass of the copper powder when the copper powder dispersion is prepared. The above is more preferably 0.075 g or more, further preferably 0.10 g or more, or may be, for example, an amount in the range of 0.025 to 0.500 g, 0.025 to 0.250 g, and 0.025 to 0.100 g. In a preferred embodiment, the amount of the amino decane used may be 1 g relative to the mass of the copper powder when the copper powder dispersion is prepared, and the volume of the amino decane at 25 ° C is 0.01 mL or more and 0.025 mL or more. It is preferably 0.050 mL or more, more preferably 0.075 mL or more, further preferably 0.10 mL or more, or may be, for example, in an amount ranging from 0.025 to 0.500 mL, 0.025 to 0.250 mL, and 0.025 to 0.100 mL.

In a preferred embodiment, as the aminodecane, a decane containing one or more amine groups and/or an imido group can be used. The number of amine groups and imine groups contained in the amino decane, for example It may be 1 to 4, preferably 1 to 3, and more preferably 1 to 2. In a preferred embodiment, the number of amine groups and imine groups contained in the amino decane may be one. The amino decane which is a total of the number of the amine group and the imine group contained in the amino decane may be specifically referred to as a monoamino decane, and the two amino decane may be specifically referred to as a diamino decane. The three amino decanes are specifically referred to as triamine decanes. Monoamine decane or diamino decane can be preferably used in the present invention. In a preferred embodiment, as the aminodecane, a monoamine decane containing one amine group can be used. In a preferred embodiment, the aminodecane may be at least one, for example, one amine group at the end of the molecule, preferably at the end of a linear or branched chain molecule.

As the amino decane, for example, N-2-(aminoethyl)-3-aminopropylmethyldimethoxydecane, N-2-(aminoethyl)-3-aminopropyl Trimethoxy decane, 3-aminopropyltrimethoxy decane, 1-aminopropyltrimethoxydecane, 2-aminopropyltrimethoxydecane, 1,2-diaminopropyltrimethoxy Baseline, 3-amino-1-propenyltrimethoxydecane, 3-amino-1-propynyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-triethoxy矽alkyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxydecane, N-(vinylbenzyl)-2-amino Ethyl-3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3- Aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-(N-phenyl)aminopropyltrimethoxydecane .

In a preferred embodiment, the amino decane represented by the following formula I can be used.

H ₂ NR ¹ -Si(OR ² ) ₂ (R ³ ) (Formula I)

In the above formula I, R1 is linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or a divalent group of a hydrocarbon having a heterocyclic ring or a heterocyclic ring or a C1 to C12 group having no hetero ring, R 2 is an alkyl group of C1 to C5, and R 3 is an alkyl group of C1 to C5 or an alkoxy group of C1 to C5.

In a preferred embodiment, R1 of the above formula I is linear or branched, saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, heterocyclic or non-heterocyclic. The divalent group of the hydrocarbon of C1 to C12, and more preferably R1 may be a group selected from the group consisting of a divalent group of a substituted or unsubstituted linear saturated hydrocarbon of C1 to C12, a divalent group of a substituted or unsubstituted C1 to C12 branched saturated hydrocarbon, a substituted or unsubstituted C1 to C12 linear unsaturated hydrocarbon, a divalent group, a substituted or unsubstituted C1 to C12 a divalent group of a branched unsaturated hydrocarbon, a divalent group of a substituted or unsubstituted C1 to C12 cyclic hydrocarbon, a divalent group of a substituted or unsubstituted C1 to C12 heterocyclic hydrocarbon, substituted Or a divalent group of an aromatic hydrocarbon which is not substituted with C1 to C12. In a preferred embodiment, R1 of the above formula I is a divalent group of a saturated or unsaturated chain hydrocarbon of C1 to C12, and further preferably the atom at both ends of the chain structure is a divalent having a free valence. base. In a preferred embodiment, the carbon number of the divalent group is, for example, C1 to C12, preferably C1 to C8, preferably C1 to C6, preferably C1 to C3.

In a preferred embodiment, R1 of the above formula I may be a group selected from the group consisting of: -(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 ) _j - (wherein n, m, j are integers of 1 or more) (wherein (CC) represents a triple bond of C and C) . In a preferred embodiment, R1 may be -(CH ₂ ) _n - or -(CH ₂ ) _n -NH-(CH ₂ ) _m - (wherein (CC) represents a triple bond of C and C). In a preferred embodiment, the hydrogen of the divalent group R1 may be substituted with an amine group, for example, 1 to 3 hydrogens, for example, 1 to 2 hydrogens, for example, 1 hydrogen, is substituted with an amine group.

In a preferred embodiment, n, m, and j of the above formula I may each independently be 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. For example, it may be an integer selected from 1, 2, 3, and 4, and may be 1, 2, or 3, for example.

In a preferred embodiment, R2 of the above formula I may be a C1~C5 alkyl group, preferably a C1~C3 alkyl group, and further preferably a C1~C2 alkyl group, for example, a methyl group or a B group. The group, isopropyl or propyl group is preferably a methyl group or an ethyl group.

In a preferred embodiment, R3 of the above formula I may be an alkyl group of C1 to C5, preferably an alkyl group of C1 to C3, and more preferably an alkyl group of C1 to C2, for example, It is a methyl group, an ethyl group, an isopropyl group or a propyl group, preferably a methyl group or an ethyl group. Further, R3 of the above formula I may 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, Methoxy, ethoxy, isopropoxy or propoxy is preferably methoxy or ethoxy.

The aqueous solution of the aminodecane can be mixed with the copper powder by a known method. Stirring can be suitably carried out by a known method at the time of mixing. In a preferred embodiment, the mixing can be carried out, for example, at room temperature, for example, at a temperature in the range of 5 to 80 ° C, 10 to 40 ° C, and 20 to 30 ° C.

In a preferred embodiment, the copper powder dispersion can be ultrasonically treated after mixing. The processing time of the ultrasonic treatment is selected according to the state of the copper powder dispersion, preferably from 1 to 180 minutes, more preferably from 3 to 150 minutes, further preferably from 10 to 120 minutes, and further preferably from 20 to 20 minutes. 80 minutes.

In a preferred embodiment, the ultrasonic treatment can be carried out on average at a power of preferably 50 to 600 W, and more preferably 100 to 600 W per 100 ml. In a preferred embodiment, the ultrasonic processing may preferably be 10 to 1 MHz, more preferably 20 to 1 MHz, and still preferably 50 to 1 MHz.

The copper powder in the copper powder dispersion can be separated from the dispersion by surface treatment with an amino decane in the above manner, and the surface-treated copper powder can be recovered. A known method can be used for the separation and recovery, and for example, filtration, centrifugation, decantation, or the like can be used. After separation and recovery, drying can be carried out as needed. Drying can be carried out by a known method, for example, drying can be carried out by heating. The heat drying can be carried out by, for example, heat treatment at a temperature of 50 to 90 ° C and 60 to 80 ° C, for example, 30 to 120 minutes and 45 to 90 minutes. After heating and drying, the copper powder may be pulverized as needed. Further, for the purpose of preventing rust or improving the dispersibility in the paste, the surface-treated copper powder obtained may be further adsorbed on the surface of the surface-treated copper powder.

As described above, in the preferred embodiment, the copper powder for surface treatment can be made of copper powder produced by a wet method. In a preferred embodiment, as a method for producing copper powder produced by a wet method, copper powder produced by the following method may be used, which comprises the steps of: adding oxidation to an aqueous solvent containing an acacia additive; a step of preparing a slurry by cuprous copper; and a step of disproportionation reaction by adding dilute sulfuric acid to the slurry at a time within 5 seconds. In a preferred embodiment, the slurry may be kept at room temperature (20 to 25 ° C) or lower, and a disproportionation reaction may be carried out by adding dilute sulfuric acid which is also kept at room temperature or lower. In a preferred embodiment, the slurry may be maintained at 7 ° C or lower, and a disproportionation reaction may be carried out by adding dilute sulfuric acid which is also kept at 7 ° C or lower. In a preferred embodiment, the addition of dilute sulfuric acid may be carried out at a pH of 2.5 or less, preferably at a pH of 2.0 or less, and more preferably at a pH of 1.5 or less. In a preferred embodiment, the addition of dilute sulfuric acid in the slurry may be within 5 minutes, preferably within 1 minute, further preferably within 30 seconds, further preferably within 10 seconds, and further preferably 5 minutes. Added within seconds. In a preferred embodiment, the disproportionation reaction can be completed within 10 minutes. In a preferred embodiment, the concentration of gum arabic in the slurry may be from 0.229 to 1.143 g/L. As the cuprous oxide, cuprous oxide used in a known method can be used, and it is preferable to use cuprous oxide particles, the particle size of the cuprous oxide particles, and the like, and particles of copper powder formed by disproportionation reaction. Since the particle diameter and the like are not directly related, coarse-grained cuprous oxide particles can be used. The principle of the disproportionation reaction is as follows: Cu ₂ O+H ₂ SO ₄ →Cu↓+CuSO ₄ +H ₂ O.

The copper powder obtained by the disproportionation may also be washed, rustproof, filtered, dried, crushed, classified, and then mixed with an amino decane, but in a preferred embodiment, it may be washed as needed. After being cleaned, rustproof, and filtered, it is directly mixed with an aqueous solution of amino decane without drying.

In a preferred embodiment, the copper powder obtained by the disproportionation reaction has an average particle diameter of 0.25 μm or less as measured by a laser diffraction type particle size distribution measuring apparatus. In a preferred embodiment, the D10, D90, and Dmax of the copper powder obtained by the disproportionation reaction determined by the laser diffraction type particle size distribution measuring device satisfy [Dmax≦D50×3, D90≦D50×2. The relationship of D10 ≧ D50 × 0.5], and the distribution of the particle diameter has a single peak. In a preferred embodiment, the copper powder obtained by the above disproportionation reaction has a particle size distribution of a single peak (having a single peak) in the measurement using a laser diffraction type particle size distribution measuring apparatus. In a preferred embodiment, the value measured by the laser diffraction type particle size distribution measuring apparatus is [D50 ≦ 1.5 μm], preferably [D50 ≦ 1.0 μm], and further preferably [D50 ≦ 0.5 μm, Dmax ≦ 1.0 μm]. Laser diffraction type As the degree distribution measuring device, for example, SALD-2100 manufactured by Shimadzu Corporation can be used.

The surface-treated copper powder obtained by the present invention has excellent sintering retardation. As an index of the sintering retardation, there is a sintering start temperature. It refers to the temperature at which the powder compact composed of the metal powder is heated in a reducing environment and when a certain volume change (shrinkage) occurs. In the present invention, a temperature at which a volume shrinkage of 1% is generated is taken as a sintering start temperature. Specifically, the measurement was carried out as described in the examples. The sintering start temperature is high, indicating that the sintering retardation is excellent.

In a preferred embodiment, the surface-treated copper powder of the present invention may have a sintering start temperature of 450 ° C or higher, preferably 500 ° C or higher, more preferably 600 ° C or higher, and still more preferably 700 ° C or higher. Further, it is preferably 780 ° C or higher, more preferably 800 ° C or higher, further preferably 810 ° C or higher, further preferably 840 ° C or higher, further preferably 900 ° C or higher, further preferably 920 ° C or higher, and further Good for 950 ° C or more. The surface-treated copper of the present invention is used in the range of 500 to 600 ° C of the conventional ultrafine powder (average particle diameter of 0.2 to 0.4 μm) which has been used for the case where a high sintering start temperature is required. The powder system uses Cu which is cheaper and more easily available than Ni, which is fine particles and has an excellent sintering retardation equivalent to or higher.

In a preferred embodiment, the surface treated copper powder of the present invention allows the compact to be heated in a reducing environment to form a sintered body. The obtained sintering system was formed into an excellent electrode. The sintering process is particularly preferably used to fabricate internal electrodes of a wafer-stacked ceramic capacitor. The sintered body is particularly preferably used as an internal electrode of a wafer laminated ceramic capacitor. In a preferred embodiment, the sintered body may have SiO ₂ having a diameter of 10 nm or more in its cross section. In a preferred embodiment, the sintered body may have SiO _{2 having} a maximum diameter of 0.5 μm or more in a cross section of 0.5/μm ² or may have a maximum diameter of 0.5 in a range of 0.0 to 0.5 / μm ² , for example. the above μm SiO _2, for example, present in the range of 0.1 to 0.5 / μm ² or more of the maximum diameter of 0.5μm SiO _2. The maximum diameter refers to the diameter of the smallest circumscribed circle of the SiO ₂ particles. In a preferred embodiment of the present invention, the precipitation of SiO ₂ particles is controlled as such, and it becomes possible to form an extremely thin electrode without deteriorating the reliability (quality) of the electrode.

In a preferred embodiment, the surface-treated copper powder may be set to 1 g with respect to the copper powder, and the adhesion amount of Si is generally 500 to 16,000 μg, preferably 500 to 3000 μg. The Si adhesion amount can be determined by ICP (Inductively Coupled Plasma Atomic Emission Spectrometry). In a preferred embodiment, it may be further set to contain 0.05% by weight or more of N based on the weight of the copper powder. The mechanism by which the decane coupling agent is adsorbed to the copper powder is not clear, and the inventors believe that it is adsorbed by the interaction between the nitrogen of the amine group at the end of the decane coupling agent and copper.

In a preferred embodiment, the surface-treated copper powder has a thickness (Si thickness) of the Si-containing layer formed by surface treatment, which is usually 0.6 to 25 nm, preferably 1.0 to 25 nm, and more preferably 1.5. ~20nm. The thickness (Si thickness) of the Si-containing layer in the present invention may be defined as a profile of the surface of the surface-treated copper powder, which will be measured by EDS (energy dispersive X-ray analysis) and will be relative to all atomic Si When the existence ratio of the Si atom having the largest depth is 100%, the amount of the Si atom present is in the range of 10% or more. Regarding the cross-section of the surface of the surface-treated copper powder, five of the at least 100 copper powder particles observed on the sample slice are selected as the surface-treated copper powder. The cross section perpendicular to the surface is measured and totaled.

In a preferred embodiment, the surface-treated copper powder may have a weight % of N relative to the copper powder of, for example, 0.05% by weight or more, preferably 0.06% by weight or more, more preferably 0.07% by weight or more, for example, It is 0.05 to 0.50% by weight, preferably 0.06 to 0.45% by weight, and more preferably in the range of 0.08 to 0.40% by weight. The weight % of N relative to the copper powder allows the copper powder to be melted at a high temperature, and the amount of adhesion of N is calculated from the NO ₂ produced.

In a preferred embodiment, the surface-treated copper powder may have a surface N of, for example, 1.0% or more, preferably 1.4% or more, in a survey by XPS (X-ray photoelectron spectroscopy) analysis, and more preferably 1.5% or more, further preferably 1.6% or more, or may be, for example, 1.0 to 6.0%, preferably 1.4 to 6.0%, more preferably 1.5 to 6.0%, still more preferably 1.6 to 6.0%, The photoelectron of N may be, for example, 1000 cps (count per second) or more, preferably 1200 cps or more, or may be, for example, 1000 to 9000 cps, preferably 1200 to 8000 cps.

In a preferred embodiment, the surface-treated copper powder may have a surface Si of, for example, 0.6% or more, preferably 0.8% or more, in a survey by XPS (X-ray photoelectron spectroscopy) analysis, and more preferably 1.0% or more, further preferably 1.1% or more, further preferably 1.2% or more, further preferably 1.3% or more, further preferably 1.4% or more, or may be, for example, 0.6 to 4.0%, preferably 0.8 to 4.0%, further preferably 1.0 to 4.0%, further preferably 1.1 to 4.0%, further preferably 1.2 to 4.0%, further preferably 1.3 to 4.0%, and further preferably 1.4 to 4.0%. The photoelectron of Si can be measured to be 1000 cps (count per second) or more, preferably 1200 cps or more, or, for example, 1000 to 12,000 cps, by irradiating a circle having a diameter of 800 μm (irradiation area: 502655 μm ² ). Good range of 1200~12000cps.

In a preferred embodiment, the surface treated copper powder may be subjected to a surface treatment after being subjected to surface treatment with an amino decane. As such a surface treatment, for example, an rust-preventing treatment using an organic rust preventive agent such as benzotriazole or imidazole can be used, and even if these ordinary treatments are carried out, the surface treatment by the amino decane does not cause detachment or the like. . Therefore, the ability The skilled artisan can perform the above-described known surface treatment as needed without losing the excellent sintering retardation. Namely, it is also within the scope of the present invention to further obtain the copper powder obtained by subjecting the surface of the surface-treated copper powder of the present invention to surface treatment without losing the excellent sintering retardation.

In the case of using a metal powder other than copper powder, the present invention can also obtain excellent characteristics by the surface treatment described above with respect to copper powder. In the case of using a metal powder other than copper powder, the present invention can also be carried out by the preferred embodiment described above with respect to the copper powder. As the metal powder, for example, any one of Pt, Pd, Ag, Ni, and Cu can be used. Preferred metal powders containing copper powder include any one of Ag, Ni, and Cu.

The present invention can be preferably carried out as described above by the adhesion of Si, and can be preferably carried out by adhesion of elements other than Si. In the case where an element other than Si is attached, the present invention can be carried out by the above-described preferred embodiment described in relation to Si. Examples of the element other than Si include any one of Ti, Al, Zr, Ce, and Sn. In addition, any one or more of Si, Ti, Al, Zr, Ce, and Sn may be mentioned as the preferable element, and any one or more of Si, Ti, and Al may be preferably used.

As described above with respect to the copper powder, the present invention can be preferably carried out by surface treatment with a decane coupling agent, but it can be preferably carried out by surface treatment with a coupling agent other than a decane coupling agent. Examples of the coupling agent other than the decane coupling agent include titanate and aluminate. When a decane coupling agent is used as a coupling agent, Si can be preferably attached; when a titanate is used as a coupling agent, Ti can be preferably attached; when an aluminate is used as a coupling agent, Preferably, Al is attached. The use of the coupling agents can be as described above for the decane coupling agent. As with the structure of the decane coupling agent, titanate and aluminate The structure is also preferably a structure in which a substituent having an amine group at the terminal is bonded to a central atom of Ti and Al.

In a preferred embodiment, the preferred adhesion amount of Si, Ti or Al adhered by the coupling agent is as described above for the copper powder, and further, for example, 1 g with respect to the metal powder, for example, 200~ The range of 16000 μg, 300-16000 μg, and 500-16000 μg is, for example, in the range of 200 to 3000 μg, 300 to 3000 μg, and 500 to 3000 μg, for example, in the range of 200 to 1500 μg, 300 to 1500 μg, and 500 to 1500 μg.

In a preferred embodiment, the thickness (Si thickness) of the Si-containing layer formed by the surface treatment of the metal powder is as described above for the copper powder, and further, the thickness of the Ti-containing layer (Ti thickness), including The thickness (Al thickness) of the Al layer may be as described above with respect to the thickness (Si thickness) of the Si-containing layer.

In a preferred embodiment, the surface Si of the surface-treated metal powder in the Survey of XPS (X-ray photoelectron spectroscopy) analysis can be set as described above for the copper powder. Further, in addition to Si adhered by surface treatment, Ti and Al may be measured by the same measurement method as Si to the same numerical range as that specified for Si.

In a preferred embodiment, the surface N of the surface-treated metal powder in the Survey of XPS (X-ray photoelectron spectroscopy) analysis can be set as described above for the copper powder.

As the titanate which can be preferably used in the present invention, an amine group-containing titanate represented by the following formula II: (H ₂ NR ¹ -O) _p Ti(OR ² ) _q (Formula II)

(wherein, in the above formula II, R1 is a linear or branched or saturated, unsaturated or unsubstituted, cyclic or acyclic, divalent or heterocyclic group having a heterocyclic or non-heterocyclic C1 to C12 hydrocarbon, R2 is A linear or branched C1-C5 alkyl group, p and q are integers from 1 to 3, p+q=4).

As R1 of the above formula II, a group exemplified as R1 of the above formula I can be preferably used. R1 of the above formula II may be, for example, a group selected from the group consisting of -(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 ) _j - (wherein n, m, j are integers of 1 or more). As a more preferable R1, -(CH ₂ ) _n -NH-(CH ₂ ) _m - (wherein n + m = 4, particularly preferably n = m = 2) can be cited.

As R2 of the above formula II, a group exemplified as R2 of the above formula I can be preferably used. In a preferred embodiment, an alkyl group of C3 may be mentioned, and a propyl group and an isopropyl group are particularly preferable.

p and q of the above formula II 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. Plenact KR44 (manufactured by AJINOMOTO FINE-TECHNO Co., Ltd.) is exemplified as the amine group-containing titanate in which the functional group is disposed in such a manner.

The metal powder of the present invention has a high sintering initiation temperature as described above in relation to the copper powder of the present invention, and by blending it, an excellent conductive metal powder paste can be produced by sintering the conductive metal powder paste. Excellent electrodes can be manufactured. The sintering start temperature of the metal powder of the present invention is as described above for the copper powder. In a preferred embodiment, the electrode obtained by the present invention is as described above for SiO _{2 of} the electrode cross section, and similarly to the TiO ₂ of the electrode cross section and/or the Al ₂ O _{3 of the} electrode cross section. It is also possible to set the size, the number, and the density as described above for the SiO _{2 of} the electrode cross section. In a preferred embodiment, the SiO ₂ of the electrode profile corresponds to the case where a decane coupling agent is used as a coupling agent for the surface treatment, and the TiO ₂ of the electrode profile corresponds to the case where the titanate is used as a coupling agent for the surface treatment, and the electrode profile Al ₂ O ₃ corresponds to the case where an aluminate is used as a coupling agent for surface treatment.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples. The invention is not limited to the following examples.

[Manufacture of surface treated copper powder]

The surface treated copper powder was produced in the following manner.

[Using wet method for milling]

20 g of copper powder for surface treatment was produced by a wet method. The copper powder obtained has the characteristics as described below. For the measurement, a laser diffraction type particle size distribution measuring apparatus (SALD-2100 manufactured by Shimadzu Corporation) was used.

D50: 0.12μm

Distribution: single peak

[Preparation of decane aqueous solution]

50 ml of an aqueous solution of decane was separately prepared using each of the following decanes.

矽: diamino decane A-1120 (manufactured by MOMENTIVE)

Amino decane A-1110 (manufactured by MOMENTIVE)

Epoxy decane Z-6040 (manufactured by DOW CORNING TORAY)

Methyltrimethoxydecane KBM-13 (manufactured by SHIN-ETSU SILICONES)

3-phenylaminopropyltrimethoxydecane (manufactured by MOMENTIVE)

Regarding the concentration, the preparation was carried out in the range of 0.5 to 15 vol%. Further, the pH was adjusted to 4 using dilute sulfuric acid except for the amine decane.

The structural formula of various decanes is as follows.

Diaminodecane A-1120: H ₂ NC ₂ H ₄ -NH-C ₃ H ₆ -Si(OCH ₃ ) ₃

Amino decane A-1110: H ₂ NC ₃ H ₆ -Si(OCH ₃ ) ₃

Epoxy decane Z-6040:

Methyltrimethoxydecane KBM-13:H ₃ C-Si(OCH ₃ ) ₃

3-phenylaminopropyltrimethoxydecane: C ₆ H ₅ -NH-C ₃ H ₆ -Si(OCH ₃ ) ₃

[Surface treatment by mixing with decane aqueous solution]

20 g of copper powder and 50 ml of each decane aqueous solution were mixed and stirred to prepare a copper powder dispersion, which was immediately subjected to ultrasonic treatment for 60 minutes (or 120 minutes) (manufactured by TECH-JAM Co., Ltd., ultrasonic cleaner, three Frequency type / W-113) (power is 100W, frequency is 100kHz). In Table 1, the time required for the 60 minutes is described as the mixing and stirring time. The operation is carried out at room temperature.

Further, as described in Table 1, agitating mixing using rotating blades will be used in several embodiments. (300 rpm) was used in combination with the above-described ultrasonic agitation, or the decane coupling agent was adsorbed to the copper powder only by stirring with a rotating blade.

The copper powder dispersion was filtered to recover the surface-treated copper powder, and dried by heating at 70 ° C for 1 hour to obtain a surface-treated copper powder.

The treatments performed on the surface-treated copper powder of each of the examples and the comparative examples are summarized in Table 1.

[Evaluation of surface treated copper powder]

The surface-treated copper powder obtained by the above operation was evaluated by the following method.

[Measurement of copper powder size]

The size of the copper powder was measured by the following means. The results are summarized in Table 2.

Laser diffraction type particle size distribution measurement (Shimadzu SLAD-2100)

[Measurement by TMA]

A sample was prepared using the surface-treated copper powder, and the sintering start temperature was measured under the following conditions using a TMA (Thermomechanical Analyzer).

Sample preparation conditions

Powder size: 7mm × height 5mm

Forming pressure: 1Ton/cm ² (1000kg weight/cm ² )

(Adding 0.5% by weight of zinc stearate as a lubricant)

Measuring condition

Installation: Shimadzu Corporation TMA-50

Heating: 5 ° C / min

Environment: 2vol% H ₂ -N ₂ (300cc/min)

Load: 98.0mN

Thus, 0.5 wt% of zinc stearate was added to the copper powder to be measured and mixed, and the mixture was packed in a cylinder having a diameter of 7 mm, and pressed into the press from the upper portion to give 1 Ton/cm ² and hold for 3 seconds. Pressurized and formed into a cylindrical shape having a height of about 5 mm. The molded body was placed in a heating furnace under the condition that the shaft was placed in the vertical direction and the load was applied to the axial direction at a rate of 98.0 mN, and the temperature was increased at a rate of 5 vol% H ₂ -N ₂ (300 cc/min). °C/min, measurement range: continuous heating in 50~1000 °C, and automatically record the height change (change in expansion and contraction) of the molded body. The temperature at which the molded body starts to change in height (shrinkage) and the shrinkage ratio thereof reaches 1% is referred to as "sintering start temperature". The measurement results of the sintering start temperatures of the surface-treated copper powders of the respective examples and comparative examples are summarized in Table 3.

The sintered body formed by raising the temperature by this TMA was observed by TEM, and the number of SiO ₂ having a maximum diameter of 0.5 μm or more was counted. The results obtained are summarized in Table 3.

Device: STEM

Profile TEM image magnification: 200000 times (200,000 times)

[analysis]

Si and N attached to the surface of the surface-treated copper powder were analyzed under the following conditions. The results are summarized in Table 3.

Surface N and surface Si: 0.5 g of copper powder was filled in a cylindrical container having a diameter of 0.5 mm, and the bottom surface was covered with a gap-free covering. The XPS survey was conducted on the top of the copper powder covered with a cylindrical container. (Semi-quantitative analysis of N and Si attached to the surface of the upper half of the copper powder sphere)

Device: 5600MC manufactured by ULVAC-PHI

Ultimate vacuum: 5.7×10 ^-9 Torr

Excitation source: monochromatic AlK α

Power: 210W

Detection area: 800μm

Incident angle, take-out angle: 45°

Use neutralizing gun

[Anti-rust treatment of surface treated copper powder]

In order to confirm that the sintering delay of the present invention can be maintained even after the surface-treated copper powder obtained in the above Example 4 is subjected to the rust-preventing treatment, the following experiment (Example 9) was carried out.

[Method of anti-rust treatment]

After the copper powder of Example 4 was obtained, it was dispersed in 100 mL of a benzotriazole aqueous solution (0.1 g/L) for rust-preventing treatment, and stirred and rotated at 500 rpm for 10 minutes by a rotating blade to carry out filtration and drying (nitrogen environment). Under 70 ° C × 1 h), copper powder which was further subjected to rust prevention treatment (Example 9) was obtained.

[Evaluation of copper powder by anti-rust treatment]

The rust-proof treated copper powder was evaluated in the same manner as in the above-described Example 4, and the results are summarized in Tables 1 to 3. Further, regarding Example 9, the size of the treated copper powder in Table 2 is the size of the copper powder after the rust-preventing treatment, and the evaluations in Table 3 are also the results regarding the rust-proof treated copper powder.

In addition to the above Comparative Examples 1 to 4, tetraethoxy decane (TEOS) was used as a decane coupling agent, and copper powder was surface-treated with ammonia as a catalyst to carry out a comparative experiment, but in the case of using tetraethoxy decane At the time, the surface-treated copper powder obtained was agglomerated, and was formed into a state in which it was considered that the surface treatment and the particle diameter were not uniformly obtained by visual observation. In this case, D50 = 0.13 μm and Dmax = 0.44 μm before surface treatment, but D50 = 0.87 μm and Dmax = 3.1 μm after surface treatment, and either of them increased by about 7 times. Further, regarding the particle size distribution, a single peak before the surface treatment becomes a double peak.

As a representative example, a TEM image (40,000 times) of the cross section of the sintered body obtained from the surface-treated copper powder of Example 5 is shown in Fig. 1 . The white portion is sintered copper and the black portion is SiO ₂ particles. It was confirmed by separately performing EDS analysis for the SiO ₂ particles. Further, in order to polish the cross section, the surface was subjected to precision focused ion beam (FIB) processing to obtain a scanning electron microscope (SEM) photograph, thereby counting the number of SiO ₂ particles.

As a representative example, the results of XPS measurement of the surface of the surface-treated copper powder of Example 5 are shown in Fig. 2, and the results of XPS measurement of the surface of the surface-treated copper powder of Comparative Example 2 are shown in Fig. 3. In Fig. 2, a peak indicating the presence of N on the surface was observed in the vicinity of the horizontal axis 400eV, but in Fig. 3, no peak indicating the presence of N on the surface was observed in the vicinity of the corresponding horizontal axis 400eV. Thus, a peak indicating the amount of N present on the surface was observed on the surface of the surface-treated copper powder of Example 5, and on the other hand, no surface was observed on the surface of the surface-treated copper powder of Comparative Example 2. The peak of the amount of N.

According to these results, it is understood that the surface-treated copper powder produced by the mixed amine decane aqueous solution of the present invention has an extremely simple method of production, and is a copper powder having a small size, but has the same level as the fine powder obtained from the nickel alloy. High sintering start temperature. Further, the surface-treated copper powder can be produced by sintering the same electrode as the electrode of the wafer-laminated ceramic capacitor, and the sintered body produced (formed) in this manner is used in the above-described surface treatment. Copper powder, but in the cross section of the sintered body, the number (number/μm ² ) of SiO ₂ particles having a large diameter (the diameter of the smallest circumscribed circle of the particles) is small.

Further, from the above results, it has been found that in order to achieve sufficient sintering retardation, it is necessary to use an amino group-containing decane having an amine group as a decane coupling agent. Further, it is understood that the amino decane is preferably an amino decane having an amine group at the terminal. In Comparative Example 4, although it appeared that a sufficient amount of Si was adhered to the copper powder, sufficient sintering retardation was not achieved. The reason for this is not clear, but the inventors speculate that the reason may be that, in Comparative Example 4, the aminodecane is not formed into a structure having an amine group at the terminal, and the benzene ring is present at the end of the amine group, thus producing In the state of steric hindrance, in the middle of the temperature rise for sintering, the amino decane or Si temporarily attached to the copper powder has been detached from the copper powder at an early stage.

Further, according to the results of the above-described Example 9, it is understood that the surface-treated copper powder of the present invention can maintain its excellent properties even after being subjected to surface treatment with an amine-based decane and further subjected to a surface treatment such as rust-preventing treatment. In other words, it is also within the scope of the present invention that the surface of the surface-treated copper powder of the present invention is obtained by surface treatment with an organic substance or the like in a range in which the surface treatment by the amino decane is not removed or the like. .

[Manufacturing example]

As described below, fine copper powder is produced, and the copper powder produced is surface-treated with an amino decane, whereby the surface-treated copper powder of the present invention is consistently produced by a wet method.

(1) 50 g of cuprous oxide was added to 0.2 g of gum arabic and 350 mL of pure water.

(2) Then, 50 mL of dilute sulfuric acid (25 wt%) was added in one portion.

(3) After stirring it by rotating blades (300 rpm x 10 minutes), it was allowed to stand for 60 minutes.

(4) Then, the precipitate is washed.

The washing was carried out by first removing the supernatant, adding 350 mL of pure water, stirring (300 rpm × 10 minutes), leaving it for 60 minutes, removing the supernatant, and adding 350 mL of pure water and stirring (300 rpm × After 10 minutes), leave for 60 minutes and remove the supernatant.

(5) Subsequently, treatment with an amino decane was carried out.

Amino decane treatment was carried out by adding an aqueous solution of amino decane (50 mL) and stirring for 60 minutes, at which time a rotating blade (300 rpm) + ultrasonic wave (manufactured by TECH-JAM Co., Ltd., ultrasonic cleaner three-frequency type / W-113) was used. ) (power is 100W, frequency is 100kHz). In addition to this, processing using only rotating blades (300 rpm) and processing using only ultrasonic waves were performed. As the amino decane, diaminodecane A-1120 (manufactured by MOMENTIVE Co., Ltd.) and amino decane A-1110 (manufactured by MOMENTIVE Co., Ltd.) were used.

(6) Subsequently, filtration was carried out to separate the precipitate.

(7) The separated precipitate is then dried. Drying (70 ° C × 2 h) was carried out in an air atmosphere and drying in nitrogen.

Thus, the surface-treated fine copper powder is obtained by consistent production. The surface-treated copper powder thus obtained has excellent sintering retardation similarly to the surface-treated copper powders of the above-described Examples 1 to 9, and the number of large particles of SiO ₂ present in the cross section of the sintered body is small. Moreover, this consistent production can be carried out without drying before obtaining the final product, and is simple and excellent in workability.

[Examples]

In addition to the embodiments described above, the present invention will be described in more detail by way of the following examples. The invention is not limited to the following examples.

[metal powder]

Copper fine powder, nickel powder, and silver powder were prepared as metal powder in the following order.

(copper powder) . Examples 15 to 17, Comparative Example 9

20 g of copper powder for surface treatment was produced by the above wet method. which is,

(1) 50 g of cuprous oxide was added to 0.5 g of gum arabic + 350 mL of pure water.

(2) Then, 50 mL of dilute sulfuric acid (25 wt%) was added in one portion.

(3) After stirring it by rotating blades (300 rpm x 10 minutes), it was allowed to stand for 60 minutes.

(4) Then, the precipitate is washed.

The washing system first removes the supernatant, adds 350 mL of pure water, and stirs (300 rpm × 10 minutes), and then left for 60 minutes, removes the supernatant, and adds 350 mL of pure water and stirs (300 rpm × 10 minutes). It was allowed to stand for 60 minutes to precipitate copper fine powder. In this state, particle size measurement was carried out by laser diffraction type particle size distribution measurement (Shimadzu Corporation SLAD-2100), and the particle size measurement before surface treatment was performed.

The particle size (D50, Dmax) of the obtained copper powder is shown in Table 3. For the measurement, a laser diffraction type particle size distribution measuring apparatus (SALD-2100 manufactured by Shimadzu Corporation) was used.

. Example 10

Copper powder is obtained by a chemical reduction method in accordance with Japanese Patent No. 4164009. Specifically, 2 g of gum arabic was added to 2900 mL of pure water, and then 125 g of copper sulfate was added, and 360 mL of 80% hydrazine monohydrate was added while stirring. After the addition of the hydrazine monohydrate, the temperature was raised from room temperature to 60 ° C over a period of 3 hours, and the copper oxide was further reacted for 3 hours. After completion of the reaction, the obtained slurry was filtered by a Buchner funnel (Nutsche), followed by washing with pure water and methanol, and further dried to obtain copper powder. The copper powder was mixed with an aqueous solution of a diamine decane coupling agent in the order of Example 1 to obtain a surface-treated copper powder. The characteristics were evaluated in the order of Example 1.

(nickel powder)

As the nickel powder, NF32 (D50 of 0.3 μm) manufactured by TOHO TITANIUM was used.

(silver powder)

Powdering according to Japanese Patent Laid-Open No. 2007-291513. Specifically, 12.6 g of silver nitrate was dissolved in 0.8 L of pure water, 24 mL of 25% ammonia water was added, and 40 g of ammonium nitrate was further added to prepare an aqueous solution of a silveramine wrong salt. Gelatin was added in a ratio of 1 g/L, and this was used as an electrolyte. Both the anode and the cathode were subjected to electrolysis at a current density of 200 A/m ² and a solution temperature of 20 ° C, and the electrodeposited silver particles were self-deposited. The plates were scraped off and electrolyzed for 1 hour. The silver powder obtained in this manner was filtered through a Buchner funnel, washed successively with pure water and ethanol, and dried at 70 ° C for 12 hours under an atmosphere. The silver powder was subjected to dry classification to finally obtain a silver powder having a D50 of 0.1 μm and a Dmax of 0.5 μm.

(Preparation of coupling agent aqueous solution)

50 ml of an aqueous solution of decane was separately prepared using various decanes described below.

矽: diamino decane A-1120 (manufactured by MOMENTIVE)

Methyltrimethoxydecane KBM-13 (manufactured by SHIN-ETSU SILICONES)

Titanate: Plenact KR44 containing an amine group (manufactured by AJINOMOTO FINE-TECHNO)

Plenact KR TTS (manufactured by AJINOMOTO FINE-TECHNO Co., Ltd.) which does not contain an amine group

The concentration is prepared in the range of 1 to 10 vol%. Further, the pH was adjusted to 4 using dilute sulfuric acid except for the amine-based coupling agent.

The structural formula of various decanes is as follows.

Diaminodecane A-1120: H ₂ NC ₂ H ₄ -NH-C ₃ H ₆ -Si(OCH ₃ ) ₃

Methyltrimethoxydecane KBM-13:H ₃ C-Si(OCH ₃ ) ₃

Amine-containing Plenact KR44

Side chain organic functional group

(CH ₃ ) ₂ CH-O-

Hydrophilic side chain organic functional group

-O-(C ₂ H ₄ )-NH-(C ₂ H ₄ )-NH ₂

Plenact KR TTS without amine groups

Side chain organic functional group

(CH ₃ ) ₂ CH-O-

Hydrophilic side chain organic functional group

-O-CO-(C ₁₇ H ₃₅ )

(surface treatment)

The supernatant is removed from the copper micropowder slurry obtained by the above (copper micropowder) sequence, and the copper micropowder is not dried, and is mixed with the coupling agent prepared in the above (preparation of the coupling agent aqueous solution) by any of the following methods. 60 minutes (Examples 15 to 17, Comparative Example 9).

(1) Rotating blade (300 rpm) + ultrasonic (manufactured by TECH-JAM Co., Ltd., ultrasonic cleaner three-frequency type / W-113) (power is 100 W, frequency is 100 kHz)

(2) Rotate the blade only (300 rpm)

(3) Ultrasonic only

Then, the coupler aqueous solutions were separately suction-filtered by an aspirator, and then 350 mL of pure water was added to the copper fine powder, followed by filtration. This was dried at 70 ° C for 1 hour in a nitrogen atmosphere and pulverized in a mortar. The particle size measurement was performed again in this state.

In Example 10, the surface treatment was carried out in the order of the above (1) as described in the above (copper powder).

The nickel powder obtained in the above (nickel powder) and the silver powder obtained in the above (silver powder) order are mixed with the coupling agent prepared in the above (preparation of a coupling agent aqueous solution) by the above procedure (1). The surface treatment was carried out in minutes (Examples 11 to 14 and 18 to 23, and Comparative Examples 6, 8, 10, and 11).

The results obtained are shown in Tables 4 to 6 below.

As described above, according to the present invention, in the case of using a metal powder other than copper powder, and in the case of using a coupling agent other than a decane coupling agent, a surface-treated metal powder having excellent characteristics can be obtained.

[Industrial availability]

The present invention provides a surface-treated copper powder which does not aggregate after surface treatment, and which is excellent in sintering retardation, and exhibits a high sintering onset temperature even in the case of copper particles of small particles. The surface-treated copper powder of the present invention can be produced by very simple treatment of copper powder, and the manufacturing method does not require a high degree of skill, and is excellent in workability and productivity. The present invention is an industrially useful invention.

Claims (43)

A surface-treated metal powder in which a photoelectron of N is detected above 1000 cps (count per second) in a survey of XPS, and photoelectrons of any of Ti, Al, Si, Zr, Ce, and Sn are detected. It is above 1000cps. A surface-treated metal powder having a surface N of 1% or more is detected in a survey of XPS, and any one or more of Ti, Al, Si, Zr, Ce, and Sn is detected to be 0.6% or more. The surface-treated metal powder according to the first or second aspect of the patent application is found to have a surface N of 1% or more and an average of 0.6% or more of Si, Ti or Al detected in the Survey of XPS. For the metal powder of claim 1 or 2, in the survey of XPS, the surface N is detected to be 1% or more, and the photoelectron of N is detected to be 1000 cps (count per second) or more, and Si or Ti is 0.6% or more, and photoelectrons of Si, Ti or Al are detected to be 1000 cps or more. The metal powder according to claim 1 or 2, wherein the metal powder is any one of Cu, Pt, Pd, Ag, and Ni. The metal powder according to claim 1 or 2, wherein the metal powder is copper powder. The metal powder according to claim 1 or 2, wherein at least one of Ti, Al, Si, Zr, Ce, and Sn is adsorbed by a coupling agent treatment. The metal powder according to claim 7, wherein the coupling agent is any one of decane, titanate or aluminate. The metal powder of claim 8 is treated with a coupling agent having an amine group at the end. For example, the metal powder of claim 1 or 2, wherein the metal powder is a decane coupling agent. Metal powder that has been surface treated. The metal powder of claim 10, wherein the decane coupling agent is an amino decane. The metal powder according to claim 1 or 2 has a sintering start temperature of 400 ° C or higher. The metal powder according to claim 11, wherein the amino decane is monoamino decane or diamino decane. A surface-treated metal powder obtained by further surface-treating a metal powder according to any one of claims 1 to 13 with an organic compound. A conductive metal powder paste using the metal powder of any one of claims 1 to 14. A wafer-stacked ceramic capacitor manufactured by using the paste of claim 15 of the patent application. A wafer-stacked ceramic capacitor according to claim 16, wherein SiO ₂ , TiO ₂ or Al ₂ O _{3 having} a diameter of 10 nm or more is present in the internal electrode cross section. The wafer-stacked ceramic capacitor according to claim 16 or 17, wherein SiO ₂ , TiO ₂ or Al ₂ O _{3 having} a maximum diameter of 0.5 μm or more is present in the internal electrode cross section at 0.5/μm ² or less. A multilayer substrate which is constructed by laminating a wafer laminated ceramic capacitor according to any one of claims 16 to 18. A multilayer substrate which is constructed by laminating a wafer-layered ceramic capacitor according to any one of claims 16 to 18. An electronic component mounted on a multilayer substrate of claim 19 or 20. A method for producing a surface treated metal powder comprising a metal powder and a coupling agent aqueous solution The step of preparing a metal powder dispersion by mixing. The method of claim 22, wherein the metal powder is any one of Cu, Pt, Pd, Ag, and Ni. The method of claim 22, wherein the metal powder is copper powder. The method of any one of claims 22 to 24, which comprises the step of agitating the metal powder dispersion. The method of any one of claims 22 to 24, which comprises the step of ultrasonically treating the metal powder dispersion. The method of claim 26, wherein the step of performing ultrasonic processing is the step of performing ultrasonic processing for 1 to 180 minutes. The method of any one of claims 22 to 24, comprising the steps of: filtering a metal powder dispersion to recover metal powder; and drying the filtered metal powder to obtain a surface-treated metal The step of powder. The method of claim 28, wherein the drying is carried out in an oxygen atmosphere or an inert environment. The method according to any one of claims 22 to 24, wherein the metal powder dispersion liquid phase contains 0.025 g or more of a coupling agent for 1 g of copper powder. The method of any one of claims 22 to 24, wherein the aqueous solution of the coupling agent is an aqueous solution of an amino decane represented by the following formula I: H ₂ NR ¹ -Si(OR ² ) ₂ (R ³ ) ( Formula I) (wherein, in the formula I, R1 is a linear or branched saturated or unsaturated, substituted or unsubstituted, cyclic or acyclic, C1 having a heterocyclic ring or a heterocyclic ring a divalent group of a hydrocarbon of -C12, R2 is an alkyl group of C1 to C5, and R3 is an alkyl group of C1 to C5 or an alkoxy group of C1 to C5. The method of claim 31, wherein R1 is a group selected from the group consisting of: -(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 ) _j - (wherein n, m, j are integers of 1 or more). The method of any one of claims 22 to 24, wherein the aqueous solution of the coupling agent is an aqueous solution of an amine group-containing titanate represented by the following formula II: (H ₂ NR ¹ -O) _P Ti (OR ² ) _q (Formula II) (wherein, in the formula II, R1 is linear or has a saturated or unsaturated, branched or unsubstituted, cyclic or acyclic, heterocyclic or non-cyclic a divalent group of a hydrocarbon of a heterocyclic ring C1 to C12, R2 is a linear or branched C1 to C5 alkyl group, and p and q are integers of 1 to 3, p+q=4). The method of claim 33, wherein R1 is a group selected from the group consisting of: -(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 ) _j - (wherein n, m, j are integers of 1 or more). The method of any one of claims 22 to 24, wherein the metal powder is wet Copper powder produced by the method. A method of producing a conductive metal powder paste, which is produced by blending a surface-treated metal powder produced by the manufacturing method of any one of claims 22 to 35 with a solvent and/or a binder. Conductive metal powder paste. A method of producing an electrode, comprising the steps of: blending a surface-treated metal powder produced by the manufacturing method of any one of claims 22 to 35 with a solvent and/or a binder to obtain a step of applying a conductive metal powder paste; a step of applying a conductive metal powder paste to the substrate; and a step of heating and baking the conductive metal powder paste applied to the substrate. A surface-treated metal powder manufactured by the manufacturing method of any one of claims 22 to 35. A conductive metal powder paste which is manufactured by the manufacturing method of claim 36 of the patent application. An electrode produced by the manufacturing method of claim 37 of the patent application. A metal powder which is a surface-treated metal powder produced by the manufacturing method of any one of claims 22 to 35; in the survey of XPS, the surface N is detected to be 1% or more, N The photoelectron is 1000 cps (count per second), and Si, Ti or Al is 0.6% or more, and photoelectrons of Si, Ti or Al are 1000 cps or more, and the sintering start temperature of the metal powder is 400 ° C or more. A conductive metal powder paste which is surface-treated in accordance with claim 41 of the scope of the patent application Metal powder is the original. An electrode obtained by coating a conductive metal powder paste of claim 42 and heating and firing the same; and having SiO _{2 having} a maximum diameter of 0.5 μm or more in an electrode cross section of 0.5/μm ² or less, TiO ₂ or Al ₂ O ₃ .