JP6746321B2 - Ni powder, method of manufacturing Ni powder, internal electrode paste, and electronic component - Google Patents

Description

The present invention relates to Ni powder, a method for manufacturing Ni powder, an internal electrode paste, and an electronic component.

In a monolithic ceramic capacitor, dielectric layers and internal electrode layers are alternately laminated, and external electrodes are formed on both end surfaces of a laminated body obtained by firing treatment. With such a structure, it is possible to obtain a small size and a large capacity, so that it is widely used for various applications with the recent increase in demand for mobile devices and the like.

Patent Document 1 discloses a multilayer ceramic capacitor in which internal electrodes have high continuity and are made thin.

JP, 2010-103198, A

In Patent Document 1, the continuity of the internal electrodes is enhanced by alternately applying the internal electrodes containing the ceramic particles and the internal electrodes containing no ceramic particles. However, Patent Document 1 does not make detailed reference to the paste forming the internal electrodes.

According to a study made by the present inventors, it is considered important that the metal powder contained in the internal electrode paste has a small aspect ratio and a narrow particle size distribution in order to improve the continuity of the internal electrodes.
In order to improve the continuity of the internal electrodes, when metal powder with a large aspect ratio is used, voids occur near the metal powder due to the excluded volume effect of the metal powder, so metal powder with a small aspect ratio is required. is there. When the maximum diameter of the metal powder having a large aspect ratio is large, when the metal powder is oriented perpendicular to the plane direction of the dielectric layer, it may break through the dielectric layer and short-circuit internal electrodes to cause a short circuit defect. is there. On the other hand, by mixing fine particles and large particles, the continuity of the internal electrode before sintering can be improved, but because of the difference in the sintering characteristics of particles with different particle sizes, the electrode continuity after sintering is A metal powder with a narrow particle size distribution is required because it decreases.
Classification is one of the methods for obtaining the metal powder. However, in the classification treatment, it is possible to remove a metal powder larger than the classification point at a classification point of an arbitrary value of about 0.6 μm to 2 μm, but a part of the metal powder smaller than the classification point is also removed at the same time. Therefore, there is a drawback that the actual product yield is significantly reduced. Therefore, when the classification treatment is performed, the cost increase of the product is inevitable including the above-mentioned expensive equipment introduction.
Furthermore, when Ni powder having an average particle size of 0.2 μm or less is used as the metal powder, it becomes difficult to remove the coarse particles by the classification treatment, so that it cannot be applied to further thinning of the internal electrode in the future.

The present invention has been made to solve the above problems, and provides a Ni powder as a metal powder that can increase the continuity of internal electrodes and prevent short-circuit defects from occurring. And a method for producing Ni powder, an internal electrode paste, and an electronic component. Further, according to the method for producing Ni powder of the present invention, since classification treatment is not required, it is possible to inexpensively produce Ni powder suitable for the internal electrode paste of the laminated ceramic capacitor and the internal electrode produced using the same. You can

That is, the Ni powder of the present invention for achieving the above object has a spherical Ni powder having an average particle diameter of 0.05 μm or more and 0.4 μm or less and an aspect ratio of 1.5 or less, and an aspect ratio of 1 The CV value of the particle diameter of the spherical Ni powder is 20% or less, and the maximum diameter thereof is 20% or less, including a connected Ni powder having one or more constricted portions in the longitudinal direction. The content of the connected Ni powder exceeding 0.8 μm is 0.3% by weight or less.

In the Ni powder of the present invention, when the average particle diameter of the spherical Ni powder is X (unit is μm) and the content of the connected Ni powder is Y (unit is wt %),
When the average particle diameter of the spherical Ni powder is 0.3<X≦0.4, Y≦0.3, and the maximum diameter of the connected Ni powder exceeds 0.8 μm,
When the average particle diameter of the spherical Ni powder is 0.05≦X≦0.3, Y≦0.1, and the maximum diameter of the connected Ni powder exceeds 0.8 μm,
When the average particle diameter of the spherical Ni powder is 0.05≦X≦0.2, Y≦0.1, and the maximum diameter of the connected Ni powder is preferably more than 0.6 μm.

In the Ni powder of the present invention, it is preferable that the average value of the diameter of the portion other than the constricted portion of the Ni powder constituting the above-mentioned connected Ni powder is in the range of 0.05 μm or more and 0.4 μm or less.

The Ni powder of the present invention preferably contains sulfur (S) on its surface. When the Ni crystallized powder obtained in the crystallization step is contacted with a treatment liquid containing a sulfur coating agent (S coating agent), the surface can be modified with sulfur (S). As the sulfur coating agent (S coating agent), various water-soluble sulfur compounds containing any of a mercapto group (-SH) and a disulfide group (-SS-) can be applied. For example, sodium hydrogen sulfide (NaSH). ) Or the like, or an organic sulfur compound such as thiomalic acid (HOOCCH(SH)CH ₂ COOH).
The surface of the Ni powder acts catalytically to accelerate the thermal decomposition of the binder resin such as ethyl cellulose contained in the internal electrode paste. May be decomposed and a large amount of decomposed gas may be generated to generate cracks. Since the action of promoting the thermal decomposition of the binder resin is suppressed when sulfur (S) is present on the surface of the Ni powder, the surface treatment (sulfur coating treatment (S coating treatment) for modifying the Ni powder with sulfur (S) is performed. )) is preferably applied.
The sulfur content in the sulfur-coated Ni powder is preferably 1.0% by weight or less, and on the other hand, even if the sulfur content exceeds 1.0% by weight, the effect of suppressing thermal decomposition of the binder resin is improved. However, a gas containing sulfur is likely to be generated during firing during the production of the monolithic ceramic capacitor, which may corrode the monolithic ceramic capacitor producing apparatus, which is not preferable.

The method for producing Ni powder according to the present invention comprises a first solution containing a water-soluble nickel salt, a metal salt containing at least one element selected from the group consisting of Au, Cu, Pd and Pt, and a complexing agent. And a step of preparing a second solution containing an alkali metal hydroxide, a step of preparing a third solution containing hydrazine, the first solution, the second solution, the second The method for producing a Ni powder, comprising: mixing the solution of No. 3 to produce a fourth solution; and depositing Ni powder in the fourth solution, wherein the step of producing the fourth solution is Depending on the number of moles of Ni precipitated from the fourth solution, the number of moles of the complexing agent contained in the first solution is within the range of 0.26 moles to 0.44 moles per mole of Ni. The second solution is controlled such that the mixing amount of the solution of No. 1 is controlled so that the number of moles of the alkali metal hydroxide contained in the second solution becomes 2.84 to 4.26 mol per 1 mol of Ni. Is controlled so that the number of moles of the hydrazine contained in the third solution is 1.66 moles or more and 2.50 moles or less per 1 mole of Ni. Is characterized by.

In the method for producing Ni powder of the present invention, the complexing agent is preferably an organic acid having at least one carboxy group.

In the step of producing the fourth solution of the method for producing Ni powder of the present invention, the temperatures of the first solution, the second solution, and the third solution are set to 45° C. or higher and 65° C. or lower. It is preferable. In the step of producing the fourth solution of the method for producing Ni powder of the present invention, the second solution and the third solution are mixed in advance, and the mixed solution is added to the first solution. It is preferable to carry out the procedure of dropping and mixing with the solution. Further, when the mixed solution of the second solution and the third solution is added dropwise to the first solution, the time for dropping the mixed solution is preferably 160 seconds or less.

In the method for producing Ni powder of the present invention, it is preferable to add a sulfur coating agent (S coating agent) to the Ni powder slurry that is an aqueous solution containing the Ni powder to obtain Ni powder surface-treated with sulfur (S). The sulfur coating agent (S coating agent) is preferably a water-soluble sulfur compound containing at least one of a mercapto group (-SH) and a disulfide group (-SS-).

The internal electrode paste of the present invention is characterized by containing the Ni powder of the present invention and an organic solvent.

An electronic component of the present invention is an electronic component formed by forming an internal electrode layer using the internal electrode paste of the present invention, including a plurality of laminated dielectric layers and a plurality of internal electrode layers, A first main surface and a second main surface which face each other, a first side surface and a second side surface which face each other in a width direction orthogonal to the stacking direction, a first end surface which faces a length direction orthogonal to the stacking direction and the width direction, and A laminated body having a second end face, and the internal electrode layer being exposed at the first end face and the second end face; and an external portion connected to the internal electrode layer and provided on the end face of the laminated body. And an electrode.

According to the present invention, it is possible to provide the Ni powder as the metal powder, which can increase the continuity of the internal electrodes and can prevent the occurrence of a short circuit defect.

FIG. 1 is a perspective view schematically showing an example of a laminated ceramic capacitor which is an electronic component of the present invention. FIG. 2 is a perspective view schematically showing an example of a laminated body of the laminated ceramic capacitor shown in FIG. FIG. 3 is an LT cross-sectional view including the L direction and the T direction of the monolithic ceramic capacitor shown in FIG. FIG. 4 is a WT sectional view including the W direction and the T direction of the monolithic ceramic capacitor shown in FIG. FIG. 5 is an example of a scanning electron micrograph (SEM image) of the Ni powder of the present invention. FIG. 6A is a schematic diagram showing an example of spherical Ni powder, and FIG. 6B is a schematic diagram showing an example of connected Ni powder. 7(a), 7(b) and 7(c) are examples of the production flow of the Ni powder of the present invention.

Hereinafter, the Ni powder, the method for manufacturing the Ni powder, the internal electrode paste, and the electronic component of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following configurations, and may be appropriately modified and applied without departing from the scope of the present invention. It should be noted that a combination of two or more of the respective desirable configurations of the present invention described below is also the present invention.

Examples of electronic components of the present invention that can be manufactured using the internal electrode paste containing the Ni powder of the present invention include multilayer ceramic capacitors, inductors, piezoelectric components, thermistors, and the like. Hereinafter, a laminated ceramic capacitor will be described as an example of the electronic component of the present invention.

The monolithic ceramic capacitor includes a laminated body and external electrodes provided on the end faces of the laminated body. FIG. 1 is a perspective view schematically showing an example of a laminated ceramic capacitor which is an electronic component of the present invention. The monolithic ceramic capacitor 1 is provided with an external electrode 100 on an end surface of a laminated body 10. In the laminated body 10, the length direction, the width direction, and the laminating direction are defined by double-headed arrows L, W, and T, respectively.

FIG. 2 is a perspective view schematically showing an example of a laminated body of the laminated ceramic capacitor shown in FIG. 3 is an LT sectional view including the L direction and the T direction of the monolithic ceramic capacitor shown in FIG. 1, and FIG. 4 is a WT sectional view including the W direction and the T direction of the monolithic ceramic capacitor shown in FIG.

The laminated body 10 includes a plurality of laminated dielectric layers 20 and a plurality of internal electrode layers 30, and has a first principal surface 11 and a second principal surface 12 facing each other in the laminating direction and a width direction orthogonal to the laminating direction. The first side surface 13 and the second side surface 14 that face each other, and the first end surface 15 and the second end surface 16 that face each other in the length direction orthogonal to the stacking direction and the width direction are included. The laminate 10 preferably has rounded corners and ridges. The corner portion is a portion where the three surfaces of the laminated body 10 intersect, and the ridge portion is a portion where the two surfaces of the laminated body 10 intersect.

The length direction, the width direction, and the stacking direction shown in FIG. 1 are orthogonal to each other. The stacking direction is a direction in which the plurality of dielectric layers 20 and the plurality of internal electrode layers 30 forming the stack 10 are stacked. Further, the length direction is a direction in which the external electrodes face each other when the external electrodes are provided at both ends of the laminated body (direction in which a plurality of different external electrodes exist).

A cross section of an electronic component or a multilayer body represented by a multilayer ceramic capacitor, which intersects the first end surface 15 or the second end surface 16 of the multilayer ceramic capacitor 1 or the multilayer body 10 and is along the stacking direction, is referred to as an LT section. FIG. 3 is an LT sectional view of the monolithic ceramic capacitor 1. In addition, a cross section of the electronic component (multilayer ceramic capacitor) or the multilayer body which intersects the first side surface 13 or the second side surface 14 of the multilayer ceramic capacitor 1 or the multilayer body 10 and is along the stacking direction is referred to as a WT cross section. FIG. 4 is a WT sectional view of the monolithic ceramic capacitor 1.

As shown in FIG. 2, the first end surface 15 and the second end surface 16 are surfaces where the internal electrode layer 30 is exposed, and the external electrodes 100 can be provided on the first end surface 15 and the second end surface 16, respectively. .. The internal electrode layer 30 may be exposed on the first side surface 13 and the second side surface 14.

As shown in FIG. 3, the laminated body 10 has a plurality of laminated dielectric layers 20 and a plurality of internal electrode layers 30, and the plurality of internal electrode layers 30 are exposed at least on the first end surface 15 of the laminated body 10. Then, the plurality of first internal electrode layers 35 connected to the external electrodes 100 provided on the first end surface 15 and the external electrodes 100 provided on the second end surface 16 exposed at least on the second end surface 16 of the stacked body 10. And a plurality of second internal electrode layers 36 connected to each other. With such a configuration, it is possible to exhibit good performance as a monolithic ceramic capacitor.

The average thickness of the plurality of dielectric layers 20 is preferably 0.1 μm or more and 5 μm or less, for example. As a material of each dielectric layer, for example, a ceramic material containing barium titanate (BaTiO ₃ ), calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), calcium zirconate (CaZrO ₃ ), or the like as a main component. including. In addition, each dielectric layer 20 is a component having a smaller content than the main component, such as a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Ni compound, as a sub-component having a smaller content than the main component. You may use what added.

Further, the outer layer portion 40 formed by only the dielectric layers 20 may be provided outside the laminated dielectric layers 20 and the internal electrode layers 30. The outer layer portion 40 is a dielectric layer located on both main surface sides of the laminated body 10 and between the main surface and the inner electrode layer 30 closest to the main surface. The region sandwiched between both outer layer portions 40 can also be called an inner layer portion. The thickness of the outer layer portion 40 is preferably 5 μm or more and 30 μm or less.

The number of dielectric layers to be laminated on the laminated body 10 is preferably 20 or more and 1500 or less. This number includes the number of dielectric layers that will be the outer layer portion 40.

Regarding the dimensions of the laminate 10, the length along the length direction is 80 μm or more and 3200 μm or less, the length along the width direction is 80 μm or more and 2600 μm or less, and the length along the stacking direction is 80 μm or more and 2600 μm or less. preferable.

The plurality of internal electrode layers 30 include first internal electrode layers 35 and second internal electrode layers 36 that are alternately arranged in the stacking direction. The first internal electrode layer 35 has a facing portion that faces the second internal electrode layer 36 with the dielectric layer 20 interposed therebetween, and a lead portion that is drawn from the facing portion to the first end surface 15 and is exposed to the first end surface 15. Have. The second internal electrode layer 36 has a facing portion facing the facing portion of the first internal electrode layer 35 with the dielectric layer 20 interposed therebetween, and a lead-out portion that is drawn from the facing portion to the second end face 16 and exposed to the second end face 16. And a department. Each internal electrode layer 30 has a substantially rectangular shape when viewed in a plan view from the stacking direction. In this way, the capacitance is formed by the internal electrode layers facing each other across the dielectric layer in each facing portion. As a result, the monolithic ceramic electronic component functions as a capacitor.

As shown in FIG. 3, a portion that is located between the facing portion and the end surface and that includes the lead portion of either the first internal electrode layer or the second internal electrode layer is the L gap of the stacked body. The length in the lengthwise direction of the L gap of the laminate is preferably 5 μm or more and 30 μm or less. The length of the L gap in the length direction of the stacked body is the length indicated by a double-headed arrow L _Gap in FIG. 3.

Further, as shown in FIG. 4, the portion located between the facing portion and the side surface is the W gap of the stacked body. The widthwise length of the W gap of the laminate is preferably 5 μm or more and 100 μm or less. The widthwise length of the W gap of the stacked body is the length indicated by a double-headed arrow W _Gap in FIG. 4.

The external electrode 100 is provided on the end faces (first end face 15 and second end face 16) of the stacked body 10, and further, the first main surface 11, the second main surface 12, the first side surface 13 and the second side surface 14. To cover a portion of each surface. The external electrode 100 is connected to the first internal electrode layer 35 at the first end surface 15 and to the second internal electrode layer 36 at the second end surface 16.

As shown in FIG. 3, the external electrode 100 has a base layer 60 and a plating layer 61 arranged on the base layer 60. The underlayer 60 shown in FIG. 3 is a baking layer containing glass and a metal, and the glass forming the baking layer preferably contains Si and other elements (B, Ba, Al). The metal forming the baking layer preferably contains at least one element selected from the group consisting of Cu, Ni, Ag, Pd, Ag-Pd alloy, and Au.

The baking layer is one in which a conductive paste containing glass and a metal is applied to a laminated body and baked, and may be baked at the same time as the internal electrode layers, or may be baked after baking the internal electrodes. Good. The thickness of the baking layer (thickness of the thickest part) is preferably 5 μm or more and 300 μm or less. Further, a plurality of baking layers may be provided.

The base layer forming the external electrode is not limited to the baking layer, and may be a resin layer or a thin film layer. When the underlayer is a resin layer, the resin layer is preferably a resin layer containing conductive particles and a thermosetting resin. When the resin layer is formed as the base layer, the resin layer may be directly formed on the laminate without forming the baking layer. The thickness of the resin layer (thickness of the thickest part) is preferably 5 μm or more and 300 μm or less. Moreover, the resin layer may be a plurality of layers.

When the underlayer is a thin film layer, the thin film layer is formed by a thin film forming method such as a sputtering method or a vapor deposition method, is a layer on which metal particles are deposited, and has a thickness of 1 μm or less. preferable.

The plating layer 61 disposed on the underlayer 60 preferably contains, for example, at least one element selected from the group consisting of Cu, Ni, Sn, Ag, Pd, Ag-Pd alloy, and Au. The plating layer may be a plurality of layers. A two-layer structure of a Ni plating layer and a Sn plating layer is preferable. The Ni plating layer can prevent the underlayer from being eroded by the solder when mounting the electronic component, and the Sn plating layer improves the wettability of the solder when mounting the electronic component, and easily Can be implemented. The thickness of one plating layer is preferably 5 μm or more and 50 μm or less.

The external electrode does not have to have a base layer, and may be a plating layer that is directly provided on the laminate and is directly connected to the internal electrode layer. However, as a pretreatment, a catalyst may be provided on the laminated body and a plated layer provided thereon may be used.

The plating layer directly connected to the internal electrode layer preferably includes a first plating layer and a second plating layer provided on the first plating layer. The first plating layer and the second plating layer are, for example, plated with at least one metal selected from the group consisting of Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi and Zn, or an alloy containing the metal. It is preferable to include. Since the electronic component of the present invention uses Ni as the metal forming the internal electrode layers, it is preferable to use Cu, which has good bonding properties with Ni, as the first plating layer. Moreover, it is preferable to use Sn or Au having good solder wettability as the second plating layer. In addition, it is preferable to use Ni having a solder barrier performance as the first plating layer.

The second plating layer is formed as needed, and the external electrode may be composed of only the first plating layer. The second plating layer may be provided as the outermost layer of the plating layer, or another plating layer may be provided on the second plating layer. The thickness of each plated layer is preferably 1 μm or more and 50 μm or less. Further, it is preferable that the plating layer does not contain glass. The metal ratio per unit volume of the plating layer is preferably 99% by volume or more. The plating layer is formed by grain growth along the thickness direction and is preferably columnar.

The internal electrode layer 30 is a layer including the first internal electrode layer 35 and the second internal electrode layer 36. The internal electrode layer 30 is a layer containing Ni formed by using the internal electrode paste of the present invention containing the Ni powder of the present invention. A detailed description of the Ni powder of the present invention and the internal electrode paste of the present invention will be given later. The internal electrode layer 30 may include, in addition to Ni, another type of metal, or dielectric particles having the same composition as the ceramic contained in the dielectric layer.

The number of the internal electrode layers 30 laminated on the laminate 10 is preferably 2 or more and 1000 or less. The average thickness of the plurality of internal electrode layers 30 is preferably 0.1 μm or more and 3 μm or less.

The average thickness of each of the plurality of internal electrode layers 30 and the plurality of dielectric layers 20 is measured as follows. First, a cross section orthogonal to the length direction of the laminate exposed by polishing is observed with a scanning electron microscope (SEM). Next, the thickness is measured on a total of 5 lines including a center line along the stacking direction that passes through the center of the cross section of the stack and two lines drawn from this center line at equal intervals on both sides. The average of these five measurements is used. In order to obtain a more accurate average thickness, the above five measured values are obtained for each of the upper part, the central part and the lower part in the stacking direction, and the average value of these measured values is taken as the average thickness.

The electronic component of the present invention can be used as an electronic component built in a board and also as an electronic component mounted on the surface of the board.

Hereinafter, the Ni powder, the method for producing the Ni powder, and the internal electrode paste of the present invention will be described.

The Ni powder of the present invention has a spherical Ni powder having an average particle size of 0.05 μm or more and 0.4 μm or less and an aspect ratio of 1.5 or less, and an aspect ratio of more than 1.5, and one position in the longitudinal direction. The CV value of the particle diameter of the spherical Ni powder including the above-mentioned connected Ni powder having the constricted portion is 20% or less, and the maximum diameter of the connected Ni powder exceeds 0.8 μm. Is less than 0.3% by weight. FIG. 5 is an example of a scanning electron micrograph (SEM image) of the Ni powder of the present invention. That is, the Ni powder of the present invention is a powder containing two kinds of Ni powder, that is, spherical Ni powder and connected Ni powder.

FIG. 6A is a schematic diagram showing an example of spherical Ni powder, and FIG. 6B is a schematic diagram showing an example of connected Ni powder.
The spherical Ni powder is a Ni powder having an average particle diameter of 0.05 μm or more and 0.4 μm or less and an aspect ratio of 1.5 or less. The CV value of the particle diameter of the spherical Ni powder is 20% or less. The CV value is an index showing variation in particle size, and is calculated based on the formula of (standard deviation/average value)×100[%].
When the average particle diameter of the spherical Ni powder is 0.4 μm or less, it can be suitably used for the internal electrode of the laminated ceramic capacitor having a thin layer. When the average particle diameter of the spherical Ni powder is 0.05 μm or more, handling of the dried Ni powder becomes easy.
If the CV value of the spherical Ni powder exceeds 20%, it may be difficult to apply it to a laminated ceramic capacitor having a thin layer due to the wide particle size distribution. Since the narrower the particle size distribution is, the better the lower limit of the CV value is not particularly limited.
When the aspect ratio of the spherical Ni powder exceeds 1.5, voids are likely to be formed in the vicinity of the particles due to the excluded volume effect, which deteriorates the electrode continuity. The lower the aspect ratio, the better, so the lower limit is not particularly limited.
The particle size and CV value are measured by observing the Ni powder with a scanning electron microscope (SEM) at a magnification of 20,000 times or more and 50,000 times or less. Then, the observed image can be obtained by image analysis using image analysis software. For example, it is taken in by A image-kun (registered trademark), which is an integrated application of IP-1000PC manufactured by Asahi Kasei Engineering Co., Ltd., and the circularity threshold value 100 (the circularity threshold value 100 detects only spherical Ni powder). By performing image analysis, the particle diameter of the spherical Ni powder can be obtained, and the “average particle diameter” and “CV value” can be calculated from the results.

The aspect ratio of spherical Ni powder can be measured as follows. The Ni powder is observed using a scanning electron microscope (SEM), and 100 single-particle Ni powders (non-connected Ni powders) are extracted from the SEM image at a magnification of 10,000 times. In the SEM image of each Ni powder, the longest diameter is the long axis, and the longest diameter in the direction perpendicular to the long axis direction is the short axis. The long axis/short axis ratio (value obtained by dividing the long axis by the short axis) Ask. Next, the average value of the major axis/minor axis ratios of the 100 Ni powders is calculated, and the average value is used as the aspect ratio.

The connected Ni powder is an Ni powder having an aspect ratio of more than 1.5 and having one or more constricted portions in the longitudinal direction. Typically, it is Ni powder formed by connecting a plurality of spherical Ni powders, and the part where the spherical Ni powders are connected to each other becomes a part having a diameter smaller than the diameter of the sphere and becomes a constricted part. The presence or absence of the constricted portion can be determined by observing the Ni powder with a scanning electron microscope (SEM).

The aspect ratio of the connected Ni powder is calculated in the same manner as that of the spherical Ni powder by extracting 10 connected Ni powders from the SEM image in the same manner as the aspect ratio of the spherical Ni powder. be able to.

In the Ni powder of the present invention, the content of the linked Ni powder having a maximum diameter exceeding 0.8 μm is 0.3% by weight or less. If the average particle diameter of the spherical Ni powder is X (unit is μm) and the content of the connected Ni powder is Y (unit is mass %), the average particle diameter of the spherical Ni powder is 0.3< In the case of X≦0.4, Y≦0.3, and it is preferable that the maximum diameter of the linked Ni powder exceeds 0.8 μm. Similarly, when the average particle diameter of the spherical Ni powder is 0.05≦X≦0.3, Y≦0.1, and the maximum diameter of the connected Ni powder is preferably more than 0.8 μm. .. When the average particle diameter of the spherical Ni powder is 0.05≦X≦0.2, Y≦0.1, and the maximum diameter of the connected Ni powder is preferably more than 0.6 μm. ..
Since it is a manufacturing method in which the amount of connected Ni powder can be reduced as the particle size becomes smaller, it can be suitably used for the internal electrode of a laminated ceramic capacitor having a thin layer. The lower limit value is better as it is smaller, and is not particularly limited.
The content of linked Ni powder having a maximum diameter exceeding 0.8 μm can be evaluated by filtration with an isopore membrane filter. Specifically, 0.1 g of Ni powder is dispersed in 100 mL of water, and the Ni powder remaining on the isopore membrane filter having a pore diameter of 0.8 μm is a connected Ni powder having a maximum diameter of 0.8 μm. It can be evaluated by quantifying the remaining Ni powder by ICP (high frequency inductively coupled plasma emission). In addition, in the case of spherical Ni powder having an average particle diameter of 0.05 μm or more and 0.2 μm or less, the maximum diameter of the connected Ni powder may be 0.8 μm or less, but any isopore membrane filter may be used. Can be evaluated by. For example, it is possible to quantify the connected Ni powder exceeding 0.6 μm.

In the Ni powder of the present invention, the content of the linked Ni powder having a maximum diameter exceeding 0.8 μm is as small as 0.3% by weight or less. Then, the average particle size is controlled within a predetermined range, and spherical Ni powder having a small variation (CV value) of the particle size of 20% or less occupies most of the range, and the ratio of the connected Ni powder is low. Therefore, the continuity of the internal electrodes is improved when used as a metal powder forming the internal electrode paste. Further, unlike the flat metal powder, the spherical Ni powder does not break through the dielectric layer and cause a short circuit defect. Therefore, the Ni powder of the present invention can be made into the Ni powder as the metal powder which can enhance the continuity of the internal electrodes and prevent the occurrence of short circuit failure.

Further, it is preferable that the average value of the diameter of the portion other than the constricted portion of the Ni powder forming the connected Ni powder is in the range of 0.05 μm or more and 0.4 μm or less.
The Ni powder of the present invention preferably contains sulfur (S) on its surface. As will be described later, when the Ni-containing precipitate obtained in the reaction solution is washed, when it is brought into contact with a treatment solution containing a sulfur coating agent (S coating agent), its surface is modified with sulfur (S). be able to. As the sulfur coating agent (S coating agent), various water-soluble sulfur compounds containing any of a mercapto group (-SH) and a disulfide group (-SS-) can be applied. For example, sodium hydrogen sulfide (NaSH). ) Or the like, or an organic sulfur compound such as thiomalic acid (HOOCCH(SH)CH ₂ COOH).
The surface of the Ni powder acts catalytically to accelerate the thermal decomposition of the binder resin such as ethyl cellulose contained in the internal electrode paste. May be decomposed and a large amount of decomposed gas may be generated to generate cracks. Since the action of promoting the thermal decomposition of the binder resin is suppressed when sulfur (S) is present on the surface of the Ni powder, the surface treatment (sulfur coating treatment (S coating treatment) for modifying the Ni powder with sulfur (S) is performed. )) is preferably applied.
The sulfur content of the sulfur-coated Ni powder is preferably 1.0% by weight or less, more preferably 0.03% by weight or more and 0.5% by weight or less, and 0.04% by weight or more and 0.3% by weight or less. More preferable. On the other hand, even if the sulfur content exceeds 1.0% by weight, the effect of suppressing the thermal decomposition of the binder resin cannot be expected to improve, and on the contrary, a gas containing sulfur is generated during firing during the production of the monolithic ceramic capacitor. This is not preferable because it may easily occur and may corrode the monolithic ceramic capacitor manufacturing apparatus.

The method for producing Ni powder according to the present invention comprises a first solution containing a water-soluble nickel salt, a metal salt containing at least one element selected from the group consisting of Au, Cu, Pd and Pt, and a complexing agent. And a step of preparing a second solution containing an alkali metal hydroxide, a step of preparing a third solution containing hydrazine, the first solution, the second solution, the second The method for producing a Ni powder, comprising: mixing the solution of No. 3 to produce a fourth solution; and depositing Ni powder in the fourth solution, wherein the step of producing the fourth solution is Depending on the number of moles of Ni deposited from the fourth solution, the number of moles of the complexing agent contained in the first solution is 0.26 moles or more and 0.44 moles or less per mole of Ni. The second solution is controlled such that the mixing amount of the solution of No. 1 is controlled so that the number of moles of the alkali metal hydroxide contained in the second solution becomes 2.84 to 4.26 mol per 1 mol of Ni. Is controlled so that the number of moles of the hydrazine contained in the third solution is 1.66 moles or more and 2.50 moles or less per 1 mole of Ni. Is characterized by.

By producing the Ni powder under such conditions, the proportion of the connected Ni powder is reduced, and the spherical Ni particles having the average particle diameter, the aspect ratio, and the variation (CV value) of the particle diameter in the preferable ranges are obtained. It is possible to produce Ni powder, which is mostly powder.

The water-soluble nickel salt is not particularly limited as long as it is a water-soluble nickel salt, and examples thereof include nickel sulfate, nickel chloride, nickel acetate and the like.

Examples of the metal salt containing at least one element selected from the group consisting of Au, Cu, Pd and Pt include nitrates, sulfates, chlorides and the like of each metal. Examples thereof include copper sulfate, palladium chloride, hexachloroplatinic acid and the like. Hydrates of these salts may be used.

The amount of the metal salt blended is preferably such that the metal ion concentration derived from the metal salt is 5 wtppm or more and 30 wtppm or less per mol of Ni. When the metal ion concentration is within this range, the proportion of the connected Ni powder can be reduced, and the effect of suppressing short circuit defects is high.

When palladium or hexachloroplatinic acid is used as the metal salt, the average particle size of the spherical Ni powder can be reduced. Particularly, when the compounding amount of hexachloroplatinic acid is increased, the average particle size of the spherical Ni powder is 0.05 μm. Can be as small as If the compounding amount of hexachloroplatinic acid is set to 15 wtppm or more and 30 wtppm or less per 1 mol of Ni, the average particle diameter of the spherical Ni powder can be reduced to 0.05 μm, but even if it is further blended, the spherical Ni powder The average particle size does not become smaller.

The complexing agent is preferably an organic acid having at least one carboxy group, and examples thereof include trisodium citrate, malic acid, malonic acid, and succinic acid.
The complexing agent may be added in the form of a hydrate (eg trisodium citrate dihydrate).

Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. Examples of hydrazine include hydrazine hydrate.

7(a), 7(b) and 7(c) are examples of the production flow of the Ni powder of the present invention.
In the method for producing Ni powder of the present invention, Ni powder is precipitated in the fourth solution when producing the fourth solution. When the fourth solution is prepared, it is preferable that the second solution and the third solution are mixed in advance, and the mixed solution is dropped and mixed into the first solution. When the fourth solution is produced by this procedure, the CV value of the spherical Ni powder can be made particularly low. This is due to the fact that the higher the alkali, the stronger the reducing power of hydrazine, as is clear from the above-mentioned reduction reaction of hydrazine such as N ₂ H ₄ →N ₂ ↑+4H ⁺ +4e ⁻ which is a 4-electron reaction. There is. That is, as shown in FIG. 7B, a mixed solution of a second solution and a third solution which are strong alkalis, that is, a mixed solution of an alkali metal hydroxide and hydrazine is added to a metal salt as a nucleating agent and an aqueous solution. When the first solution containing a soluble nickel salt is dropped and mixed, the dropping and mixing region of the first solution always becomes a strong alkali immediately after the dropping, so that the strong reducing power of hydrazine makes the dropping solution particularly effective. Nucleation continues to occur in the dropping mixing region. In other words, local nucleation occurs for a long time, resulting in non-uniform nucleation spatially and temporally. Therefore, there is a tendency that the particle size distribution, which is an increase in the CV value, becomes broad and the proportion of the connected Ni powder increases. On the other hand, according to the procedure of FIGS. 7(a) and 7(c), the dropping mixing region at the start of dropping is weakly acidic to weakly alkaline, and the alkali becomes stronger as the dropping progresses. The generation will occur only at the end of the dropping, when the alkali becomes strong. In other words, nucleation occurs in a short time in the entire mixed fourth solution, so that the nucleation is uniform both spatially and temporally. Therefore, the particle size distribution, which is a decrease in the CV value, becomes narrow, and the proportion of the connected Ni powder can be reduced.

In addition, in the step of producing the fourth solution, it is preferable that the temperatures of the first solution, the second solution, and the third solution be 45° C. or higher and 65° C. or lower. By setting the temperature of each solution within this range, the CV value of the spherical Ni powder can be made particularly low.

In addition, when the mixed solution of the second solution and the third solution is added dropwise to the first solution, the time for dropping the mixed solution is preferably 160 seconds or less. When the time for dropping the mixed solution is 160 seconds or less, the CV value of the spherical Ni powder can be made particularly low.

When the fourth solution is prepared in this manner, Ni powder is precipitated in the fourth solution, but Ni is precipitated after dropping and mixing the mixed solution of the second solution and the third solution into the first solution. It is preferable to set the time to be not shorter than 120 minutes and not longer than 120 minutes. A precipitate containing Ni can be obtained by aging the thus obtained precipitate.

Next, it is preferable to wash the Ni powder by cooling the reaction solution containing the Ni-containing precipitate and then replacing the supernatant with pure water several times. Further, during this cleaning, the surface of the Ni powder can be modified with sulfur (S) by bringing it into contact with a treatment liquid containing a sulfur coating agent (S coating agent). The sulfur coating agent (S coating agent) is preferably an aqueous solution of a water-soluble sulfur compound containing any of a mercapto group (-SH) and a disulfide group (-SS-), and thiomalic acid (HOOCCH(SH)CH ₂ COOH), L-cysteine (HSCH ₂ CH(NH ₂ )COOH), thioglycerol (HSCH ₂ CH(OH)CH ₂ OH), dithiodiglycolic acid (HOOCH ₂ S-SCH ₂ COOH), and the like are preferable. is there. Further, it is preferable to obtain Ni powder by substituting water with acetone, drying and then crushing with an airflow crusher. The drying temperature is preferably 80°C or higher and lower than 90°C. A desired Ni powder can be obtained by the above procedure.

The internal electrode paste of the present invention is characterized by containing the Ni powder of the present invention and an organic solvent. As the organic solvent, α-terpineol, butyl carbitol, butyl carbitol acetate, alcohols and the like can be used. Further, an organic binder may be further included, and as the organic binder, ethyl cellulose resin, acrylic resin, polyvinyl butyral, methacrylic resin, or the like can be used. The internal electrode paste of the present invention can be used for forming an internal electrode layer in the electronic component of the present invention, and by using the internal electrode paste of the present invention, the continuity of the internal electrodes can be increased, In addition, it is possible to prevent a short circuit from occurring. The proportion of Ni powder in the internal electrode paste is preferably 40% by weight or more and 70% by weight or less.

Hereinafter, a method for manufacturing a laminated ceramic capacitor will be described as an example of a method for manufacturing an electronic component of the present invention.

First, a dielectric sheet and an internal electrode paste are prepared. The dielectric sheet and the internal electrode paste include a binder and a solvent, but known organic binders and organic solvents can be used. The internal electrode paste of the present invention can be used as the internal electrode paste. Next, the internal electrode paste is printed on the dielectric sheet in a predetermined pattern by, for example, screen printing or gravure printing to form an internal electrode pattern. Next, a predetermined number of outer layer dielectric sheets on which the internal electrode patterns are not printed are laminated, on top of which the dielectric sheets on which the internal electrode patterns are printed are sequentially laminated, and then the outer layer dielectric sheet is laminated thereon. A predetermined number of sheets are laminated to produce a laminated sheet. Next, the laminated sheet is pressed in the laminating direction by means such as isostatic pressing to produce a laminated block. The laminated block is cut into a predetermined size, and the laminated chip is cut out. At this time, the corners and ridges of the laminated chip may be rounded by barrel polishing or the like. Next, the laminated chip is fired to produce a laminated body. The firing temperature is preferably 900° C. or higher and 1300° C. or lower, though it depends on the materials of the dielectric and the internal electrode.

Next, external electrodes are formed on the end faces of the laminated body. When forming an external electrode having a baking layer, a conductive paste for the external electrode is applied to both end faces of the laminated body and baked to form a baking layer of the external electrode. The baking temperature is preferably 700° C. or higher and 900° C. or lower. Next, if necessary, the surface of the baking layer is plated to form a plating layer.

When a plating layer is directly formed on the surface of the laminated body as an external electrode without providing a baking layer, a plating process is performed to form a base plating film on the exposed portion of the internal electrode. Either electroplating or electroless plating may be adopted for the plating treatment, but electroless plating requires a pretreatment with a catalyst or the like in order to improve the plating deposition rate, which complicates the process. There is a disadvantage. Therefore, it is usually preferable to employ electrolytic plating. Barrel plating is preferably used as the plating method.

When forming the surface conductor, a surface conductor pattern may be printed on the outermost dielectric sheet in advance and co-firing with other dielectric sheets, etc. The surface conductor may be printed on the surface and then baked.

Hereinafter, examples in which the Ni powder of the present invention, an example of the internal electrode paste, and a laminated ceramic capacitor as an example of an electronic component are disclosed more specifically will be shown. The present invention is not limited to these examples.

(Example 1)
100 g of nickel sulfate hexahydrate and 40.3 g of trisodium citrate dihydrate were dissolved in 270 g of water so that the number of moles of trisodium citrate was 0.36 mol per 1 mol of Ni. A nickel salt solution containing copper ions was prepared by adding 0.18 g of a copper sulfate pentahydrate solution diluted to 0.4 wt% so as to be 8.2 wtppm per mol of Ni. This solution was used as the first solution.

Next, 54 g of sodium hydroxide was dissolved in 250 g of water so that the number of moles of sodium hydroxide was 3.55 mol per 1 mol of Ni contained in the first solution to be mixed, and the second solution was added. Prepared. Next, 66 g of 60% hydrazine hydrate was prepared so that the number of moles of hydrazine was 2.03 moles per 1 mole of Ni contained in the first solution to be mixed. This solution was used as the third solution.

The first solution, the second solution, and the third solution were heated to 55° C., and the second solution and the third solution were premixed. Then, the mixed solution was added to the first solution at a dropping time of 100 seconds to prepare a fourth solution, and Ni powder was deposited in the fourth solution. Then, it was aged for 30 minutes to obtain a precipitate containing Ni. Next, after cooling the reaction liquid, the supernatant liquid was replaced twice with pure water, and then thiomalic acid (other name: mercaptosuccinic acid) (HOOCCH(SH)CH ₂ ) as a sulfur coating agent (S coating agent). COOH, molecular weight: 150.15) aqueous solution was added, and the supernatant was replaced with pure water several times to treat the surface of the Ni powder with sulfur (S) and wash it. Further, after substituting water with acetone, the Ni powder was dried in an oven set at a temperature of 80° C., and crushed by an airflow crusher to obtain Ni powder.

<Measurement of average particle size and CV value>
The obtained Ni powder was observed with a scanning electron microscope (SEM) at a magnification of 20000 times, and from the SEM image, A image Kun (registered trademark) which is an integrated application of IP-1000PC manufactured by Asahi Kasei Engineering Co., Ltd. Using the image analysis, the average particle diameter of the spherical Ni powder and the CV value of the particle diameter were calculated by the above method. When the CV value was 15% or less, it was judged as ⊚, when it exceeds 15% and 20% or less is judged as ◯, and when it exceeds 20%, it is judged as x. The results are shown in Table 1.

<Sulfur content measurement>
The sulfur content of the obtained Ni powder was measured using a sulfur analyzer (manufactured by Horiba Ltd.). The results are shown in Table 1.

<Quantity of connected Ni powder>
0.1 g of Ni powder was dispersed in 100 mL of water, and the Ni powder remaining on the isopore membrane filter having a pore diameter of 0.8 μm was quantified by ICP (high frequency inductively coupled plasma emission) to obtain a maximum diameter of 0. The content of linked Ni powder exceeding 8 μm was quantified.
For the examples in which the average particle size of the spherical Ni powder was 0.2 μm or less, the same operation was performed for an isopore membrane filter having a pore size of 0.6 μm, and the maximum diameter of the connected Ni powder was 0.6 μm. The content was quantified.
The results are shown in Table 1.

<Preparation of internal electrode paste>
Next, an internal electrode paste containing this Ni powder was prepared. First, an ethyl cellulose resin as a binder resin and α-terpineol as an organic solvent are prepared, and the ethyl cellulose resin is dissolved in α-terpineol so that the mixing ratio of the ethyl cellulose resin and α-terpineol is 1:9 by volume. Then, an organic vehicle was produced. Next, the Ni powder and the organic vehicle were mixed so that the content of the Ni powder was 45% by weight, and the mixture was dispersed and kneaded using a three-roll mill, whereby the Ni powder was used as a conductive material. An electrode paste was prepared.

<Calculation of electrode coverage>
A polyvinyl butyral binder, a plasticizer, and ethanol as an organic solvent were added to BaTiO ₃ as a ceramic raw material, and these were wet mixed by a ball mill to prepare a ceramic slurry. Then, this ceramic slurry was formed into a sheet by a lip method to obtain a rectangular dielectric sheet. Next, an internal electrode paste containing Ni powder was screen-printed on the dielectric sheet to form a conductive film to be an internal electrode layer. Next, a plurality of dielectric sheets having the conductive film formed thereon were laminated so that the sides from which the conductive films were drawn out were staggered to obtain a laminated sheet. Next, this raw laminated sheet was pressure-molded and divided by dicing to obtain chips. The obtained chip was heated in an N ₂ atmosphere to burn the binder, and then fired in a reducing atmosphere containing H ₂ , N ₂ and H ₂ O gas to obtain a sintered laminated body. .. The structure of the laminated body is a structure having a plurality of dielectric layers and a plurality of internal electrode layers.

The electrode coverage of the internal electrode layers of the thus obtained laminate was calculated. The electrode coverage of the internal electrode layer was measured for each of the five samples by the following method. That is, each sample after sintering was cut at the central portion in the stacking direction, the cut surface was observed with an optical microscope, image analysis was performed to calculate the area ratio of the measured area to the theoretical area of the internal electrode layer, and the average The value was determined and used as the electrode coverage. 80% or more was judged as O and less than 80% was judged as X. The results are shown in Table 1. The electrode coverage is an index showing the continuity of the internal electrodes, and it can be said that the higher the electrode coverage, the higher the continuity of the internal electrodes.

<Calculation of short circuit defect rate>
An external electrode was formed on the obtained laminated body, a voltage of 2 V was applied using an insulation resistance measuring instrument, and a resistance value of 10 ⁵ Ω or less was determined to be a short circuit defect. N=1000 pieces were evaluated, and a short circuit defect rate of less than 1% was evaluated as ◯ and 1% or more was evaluated as x. The results are shown in Table 1.

In the following examples and comparative examples, Ni powder was obtained as follows. Each property was evaluated in the same manner as in Example 1 except for the step of obtaining Ni powder.
(Example 2)
Ni powder was obtained in the same manner as in Example 1 except that the dropping procedure of the solution of Example 1 was reversed, that is, the first solution was dropped into the mixed solution of the second solution and the third solution. ..
(Example 3)
Ni powder was obtained in the same manner as in Example 1 except that the addition amount of the copper sulfate pentahydrate solution in Example 1 was changed to 0.12 g.
(Example 4)
Ni powder was obtained in the same manner as in Example 1 except that the copper sulfate aqueous solution was added so that the copper ion concentration in Example 1 was 15 wtppm per 1 mol of Ni.
(Example 5)
Ni powder was obtained in the same manner as in Example 1 except that an aqueous palladium chloride solution was added so that the palladium ion concentration was 15 wtppm per mol of Ni, instead of the copper sulfate pentahydrate solution of Example 1.
(Example 6)
Ni powder was obtained in the same manner as in Example 1 except that hexachloroplatinic acid was added so that the platinum ion concentration was 15 wtppm per mol of Ni, instead of the copper sulfate pentahydrate solution of Example 1.
(Example 7)
Ni powder was obtained in the same manner as in Example 1 except that the amount of trisodium citrate dihydrate added in Example 1 was changed to 49.2 g so that the amount was 0.44 mol per 1 mol of Ni.
(Example 8)
Ni powder was obtained in the same manner as in Example 1 except that the amount of trisodium citrate dihydrate added in Example 1 was changed to 28.7 g so that it was 0.26 mol per mol of Ni.
(Example 9)
Ni powder was obtained in the same manner as in Example 1 except that the amount of sodium hydroxide added in Example 1 was changed to 64.8 g so as to be 4.26 mol per 1 mol of Ni.
(Example 10)
Ni powder was obtained in the same manner as in Example 1 except that the amount of sodium hydroxide added in Example 1 was changed to 43.2 g so that it was 2.84 mol per 1 mol of Ni.
(Example 11)
Ni powder was obtained in the same manner as in Example 1 except that the amount of hydrazine added in Example 1 was changed to 79.2 g of 60% hydrazine hydrate so that it was 2.50 mol per mol of Ni.
(Example 12)
Ni powder was obtained in the same manner as in Example 1 except that the addition amount of hydrazine in Example 1 was changed to 52.8 g of 60% hydrazine hydrate so that the amount of hydrazine added was 1.66 mol per 1 mol of Ni.
(Example 13)
Ni powder was obtained in the same manner as in Example 1 except that the dropping time of the mixed solution of the second solution and the third solution was changed to 160 seconds in Example 1.
(Example 14)
Ni powder was obtained in the same manner as in Example 1 except that the heating temperature of the first solution, the second solution, and the third solution in Example 1 was changed from 55°C to 65°C.
(Example 15)
Ni powder was obtained in the same manner as in Example 1 except that the heating temperatures of the first solution, the second solution, and the third solution in Example 1 were changed from 55°C to 45°C.

(Comparative Example 1)
Ni powder was obtained in the same manner as in Example 1 except that the amount of trisodium citrate added in Example 1 was changed to 53.3 g of trisodium citrate dihydrate so as to be 0.48 mol per 1 mol of Ni. Got
(Comparative example 2)
Ni powder was obtained in the same manner as in Example 1 except that the amount of trisodium citrate added in Example 1 was changed to 24.6 g so that the amount of trisodium citrate added was 0.22 mol per 1 mol of Ni. Got
(Comparative example 3)
Ni powder was obtained in the same manner as in Example 1 except that the amount of sodium hydroxide added in Example 1 was changed to 70.2 g so that it was 4.62 mol per mol of Ni.
(Comparative example 4)
Ni powder was obtained in the same manner as in Example 1 except that the amount of sodium hydroxide added in Example 1 was changed to 37.8 g so that it was 2.49 mol per mol of Ni.
(Comparative example 5)
Ni powder was obtained in the same manner as in Example 1 except that the amount of hydrazine added in Example 1 was changed to 85.8 g of 60% hydrazine hydrate so that the amount of hydrazine added was 2.70 mol per mol of Ni.
(Comparative example 6)
Example 1 was repeated except that the amount of hydrazine added in Example 1 was changed to 39.6 g of 60% hydrazine hydrate so that the amount of hydrazine added was 1.25 mol per 1 mol of Ni. No precipitate containing Ni could be obtained.

* The dropping procedure was "forward" when the mixed solution of the second solution and the third solution was dropped, and "reverse" when the first solution was dropped.

The Ni powder obtained in each example has a low CV value and a small amount of connected Ni powder, so that the electrode continuity is high, the electrode coverage is excellent, and the occurrence of short circuit defects is prevented. It was In addition, preferable results were obtained regardless of whether copper, palladium or platinum was used as the type of metal salt.

1 Multilayer ceramic capacitors (electronic parts)
10 laminated body 11 1st main surface 12 2nd main surface 13 1st side surface 14 2nd side surface 15 1st end surface 16 2nd end surface 20 Dielectric layer 30 Internal electrode layer 35 1st internal electrode layer 36 2nd internal electrode layer 40 Outer layer portion 60 Underlayer 61 Plating layer 100 External electrode

Claims (7)

Providing a first solution containing a water-soluble nickel salt, a metal salt containing at least one element selected from the group consisting of Au, Cu, Pd and Pt, and a complexing agent,
Providing a second solution containing an alkali metal hydroxide,
Providing a third solution containing hydrazine;
A step of mixing the first solution, the second solution, and the third solution to prepare a fourth solution,
A method for producing Ni powder, which comprises depositing Ni powder in the fourth solution, comprising:
The step of producing the fourth solution includes
Depending on the number of moles of Ni deposited from the fourth solution,
The mixing amount of the first solution is controlled within a range in which the number of moles of the complexing agent contained in the first solution is 0.26 mol or more and 0.44 mol or less per 1 mol of Ni,
The mixed amount of the second solution is controlled in a range in which the number of moles of the alkali metal hydroxide contained in the second solution is 2.84 mol or more and 4.26 mol or less per 1 mol of Ni,
Ni powder characterized by controlling the mixing amount of the third solution in a range in which the number of moles of the hydrazine contained in the third solution is 1.66 moles or more and 2.50 moles or less per 1 mole of Ni. Manufacturing method. The method for producing Ni powder according to claim 1, wherein the complexing agent is an organic acid having at least one carboxy group. The temperature of the said 1st solution, the said 2nd solution, and the said 3rd solution in the process of producing the said 4th solution shall be 45 degreeC or more and 65 degrees C or less, The Ni powder of Claim 1 or 2. Production method. The step of producing the fourth solution is performed by a procedure of previously mixing the second solution and the third solution and dropping and mixing the mixed solution with the first solution. 4. The method for producing Ni powder according to any one of 3 above. The production of Ni powder according to claim 4, wherein when the mixed solution of the second solution and the third solution is added dropwise to the first solution, the time for which the mixed solution is dropped is 160 seconds or less. Method. The Ni powder according to any one of claims 1 to 5, wherein a sulfur coating agent (S coating agent) is added to a Ni powder slurry that is an aqueous solution containing the Ni powder to obtain a Ni powder surface-treated with sulfur (S). Production method. The method for producing Ni powder according to claim 6, wherein the sulfur coating agent (S coating agent) is a water-soluble sulfur compound containing at least one of a mercapto group (-SH) and a disulfide group (-SS-). ..