JP2003013103A - Method for manufacturing electroconductive powder, electroconductive powder, electroconductive paste and laminated ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing an electroconductive powder having oxidation resistance, the electroconductive powder, and an electroconductive paste using such electroconductive powder, thereby to enable a binder removing treatment in an oxidative atmosphere at a temperature favorable for decomposing and removing organic materials, and to improve the yield and the productivity of a laminated ceramic electronic component in forming an inner electrode with the use of the electroconductive paste. SOLUTION: The method for manufacturing the electroconductive powder is characterized by adding and mixing reduced solution containing hydrogenated boride or/and amine borane to and with a metallic solution which contains at least one base-metal powder selected from the group consisting of Ni powder, Cu powder, and alloy powders mainly consisting of Ni and/or Cu, as well as a Co salt, to precipitate Co-B alloy powder of 50 pts. wt. against the base-metal powder 100 pts. wt., having an average particle diameter smaller than that of the base-metal powder, on the base-metal powder.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a conductive powder having oxidation resistance, a conductive powder obtained by the above-mentioned production method, a conductive paste containing the above-mentioned conductive powder, and the above-mentioned conductive powder. The present invention relates to a laminated ceramic electronic component in which internal electrodes are formed using a paste,
In particular, the present invention relates to a method for producing an electrically conductive powder having oxidation resistance, which is used as an electrically conductive paste suitable for forming internal electrodes of a laminated ceramic capacitor, an electrically conductive powder, an electrically conductive paste, and a laminated ceramic capacitor.

[0002]

2. Description of the Related Art Conventionally, a conductive paste for forming internal electrodes, which is used when a raw ceramic laminate and a paste coating film are simultaneously fired and sintered, such as a monolithic ceramic electronic component such as a monolithic ceramic capacitor. As the conductive paste, a conductive paste containing a noble metal powder such as Pd, Ag—Pd, Pt, etc., which is stable against oxidation even at high temperature and has a melting point higher than the firing temperature of the elemental ceramic, and an organic vehicle is used. Has been. However, since these precious metal powders are expensive and the price is not stable, in recent years, Ni powder, Cu powder, or a conductive paste containing a base metal powder such as a powder containing these as a main component is used. Multilayer ceramic electronic components such as low-cost monolithic ceramic capacitors and multilayer ceramic substrates on which internal electrodes are formed are produced.

In the manufacturing process of the above-mentioned monolithic ceramic electronic component, in order to prevent the oxidation of Ni powder and Cu powder, the atmosphere control in the debinding process and the main firing process is very important. Among these, in the binder removal step, in order to prevent the oxidation of these base metal powders, a neutral atmosphere such as in a nitrogen stream, or an oxidizing atmosphere at a very low temperature such that these base metal powders are not oxidized is used for the purpose of decomposing organic substances. The heat treatment is performed.

[0004]

In order to thermally decompose an organic substance, a sufficient amount of oxygen and temperature necessary for its combustion are required, but in the case of using a conventional conductive paste containing a base metal powder. However, as described above, the binder removal must be performed in a neutral atmosphere such as a nitrogen stream or in an oxidizing atmosphere at an extremely low temperature at which these base metal powders are not oxidized. Therefore, if the decomposition or removal of organic substances due to variations in the process atmosphere becomes insufficient, the residual carbon component hinders the sintering of the ceramic during the main firing, resulting in insufficient sintering of the ceramic, resulting in insufficient capacitance and insulation resistance. There is a problem that it cannot be obtained.

On the contrary, in order to ensure the thermal decomposition of the organic matter, if sufficient oxygen is supplied and the heat treatment is performed at a high temperature,
The base metal powder is oxidized at the time of debinding, and the structural failure such as layer peeling at the time of debinding due to the oxidative expansion of the base metal powder, the decrease in acquisition capacity due to insufficient sintering of the base metal powder due to oxidation, the increase in equivalent series resistance and tan δ, etc. A problem occurs. Therefore, there is a problem that delicate atmosphere management is required at the time of binder removal, process management becomes complicated and causes process defects.

As a method for solving such a problem, Japanese Patent Laid-Open Nos. 1-258306 and 1-265406 are available.
In Japanese Patent Laid-Open No. 1-80008 and Japanese Patent Laid-Open No. 1-80008,
To prevent oxidation of the base metal powder, a conductive paste containing Ni powder containing one or more kinds of B powder or B compound powder and an inorganic filler and an organic vehicle is disclosed. However, this method has a problem that when the paste kneading is insufficient, the dispersion state of the B powder or the B compound becomes non-uniform, and the oxidation resistance of the base metal powder varies.

Therefore, a method of improving the dispersion state of the B powder or the B compound by depositing the B powder or the B compound on the surface of the base metal powder can be considered. As a method of depositing a metal (alloy) on the surface of the base metal powder, for example, as disclosed in JP-A-63-27567,
A conventional electroless plating method can be mentioned. The so-called electroless plating method is a guess or experience by immersing an object to be plated in an electroless plating solution consisting of one solution obtained by appropriately adjusting a metal salt, a reducing agent, a complexing agent, a pH adjusting agent and the like. It is a method of stopping the reaction after the reaction for a time determined by the rule. However, in the case of the conventional electroless plating method, when the object to be plated is a powder, for example, since the specific surface area is larger than that of a plate-shaped object to be plated, the rate of the plating reaction is abnormally fast, and the desired metal deposition amount There is a problem that is difficult to control. In addition, the conventional electroless plating solution has a low metal salt concentration, and in the case of an object to be plated having a large specific surface area such as powder,
There is a problem that the plating solution is rapidly decomposed when the powder is charged, and the deposition of metal on the powder surface becomes insufficient.

As means for solving such a further problem, for example, in JP-A-60-59070,
A method of adding an electroless plating solution to a solution in which powder to be plated is dispersed is disclosed, and JP-A-62-62 is disclosed.
No. 30885 discloses a method of simultaneously adding two solutions, a reducing solution and a metal solution, to an aqueous solution in which a powder to be plated is dispersed. However, whichever method is used, there is a problem that reaction precipitation occurs in a place other than the vicinity of the surface of the powder to be plated, for example, the inner wall of the reaction vessel or by itself.

An object of the present invention is to solve the above-mentioned problems, and to provide a method for producing a conductive powder having oxidation resistance, a conductive powder, and a conductive paste using such a conductive powder. By providing a debinding process in an oxidizing atmosphere at a temperature sufficient for decomposing and removing organic substances, the yield and productivity of multilayer ceramic electronic components that form internal electrodes using such a conductive paste can be improved. To improve.

[0010]

In order to achieve the above object, the method for producing a conductive powder of the present invention is selected from the group consisting of Ni powder, Cu powder, and alloy powder containing Ni or / and Cu as a main component. At least one base metal powder and C
A reducing solution containing a borohydride or / and an amine borane is added to and mixed with a metal solution containing an o salt to form 100 parts by weight of the base metal powder on the surface of the base metal powder, which is smaller than the average particle size of the base metal powder. 50 parts by weight or less of Co-
It is characterized in that B alloy powder is deposited.

The conductive powder manufacturing method of the present invention preferably further comprises a heat treatment step of heat-treating the base metal powder having the Co-B alloy powder deposited on the surface thereof at 100 ° C. or higher after the above-mentioned precipitation step.

Further, it is preferable that the method for producing a conductive powder of the present invention further comprises a crushing step of crushing the base metal powder having Co-B alloy powder deposited on the surface after the above-mentioned precipitation step.

In the method for producing a conductive powder of the present invention, the average particle size of the base metal powder is preferably 1.0 μm or less.

Further, in the method for producing the conductive powder of the present invention, the average particle size of the Co--B alloy powder is preferably 0.1 μm or less and 1/2 or less of the average particle size of the base metal powder. .

The conductive powder of the present invention is characterized by being obtained by the above-mentioned production method of the present invention.

The conductive paste of the present invention is characterized by containing the above-mentioned conductive powder of the present invention and an organic vehicle.

The laminated ceramic electronic component of the present invention comprises a ceramic laminated body formed by laminating a plurality of ceramic layers,
A multilayer ceramic electronic component including a plurality of internal electrodes formed between ceramic layers, wherein the internal electrodes are formed using the conductive paste of the present invention.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION
Base metal powder to be plated, specifically Ni powder, C
A metal solution containing at least one base metal powder selected from the group consisting of u powder, an alloy powder containing Ni and / or Cu as a main component, and a Co salt is prepared, and a borohydride or By adding and mixing a reducing solution containing / and amine borane, on the surface of the base metal powder,
Smaller than the average particle size of the base metal powder, 100 base metal powder
It is characterized in that 50 parts by weight or less of Co-B alloy powder is deposited with respect to parts by weight. By mixing the base metal powder and the Co salt in advance, the reducing agent is decomposed on the powder surface by the catalytic action of the surface of the base metal powder and electrons are emitted when the reducing solution is added and mixed. Therefore, since Ni ions are present in high concentration near the base metal powder,
Immediate reduction of ions occurs, causing Co on the surface of the base metal powder.
-B alloy powder is precipitated. The average particle size and the amount of precipitation of the Co-B alloy powder can be adjusted by adjusting the concentration of borohydride or amine borane in the reducing solution and the reaction temperature of the liquid-phase reduction reaction. Although not limited, for example, a Co-B alloy powder of 0.10 μm or less can be deposited.

When depositing the Co-B alloy powder on the surface of the base metal powder, it is preferable to perform a heat treatment at 100 ° C. or higher after the precipitation and further perform a crushing treatment. By performing the heat treatment, it is possible to suppress the Co-B alloy powder from being separated from the surface of the base metal powder during the pulverization process of the powder and during the paste preparation, and the effect of the present invention becomes remarkable. Further, the precipitation of the Co-B alloy powder and the heat treatment tend to cause the powder to agglomerate. Therefore, it is preferable to perform the pulverization treatment after the heat treatment.

The average particle size of the Co-B alloy powder obtained by precipitation needs to be smaller than the average particle size of the base metal powder. When the average particle size is smaller than that of the base metal powder, the effect of the present invention is obtained in that the boron oxide coats the base metal powder as described above, and the oxidation resistance of the base metal powder is enhanced. On the other hand, when the average particle diameter of the base metal powder is equal to or larger than the average particle diameter of the base metal powder, the multilayer ceramic electronic component in which the internal electrode is formed by using the conductive paste containing the conductive powder has a property of removing the binder due to oxidative expansion of the base metal powder. Problems such as structural failure such as layer peeling, decrease in acquisition capacity due to insufficient sintering of base metal powder due to oxidation, and increase in equivalent series resistance and tan δ occur.

The amount of the Co-B alloy powder deposited on the surface of the base metal powder is 50 with respect to 100 parts by weight of the base metal powder.
It is necessary to be less than or equal to parts by weight. When the precipitation amount of the Co-B alloy powder is 50% by weight or less, an appropriate amount of Co-B alloy powder is melted and the internal electrode does not impair the function as an electrode. The lower limit of the precipitation amount of the Co-B alloy powder is not particularly limited, but the precipitation amount of the Co-B alloy powder is 0.1.
If it is about wt%, the oxidation start temperature of the conductive powder will rise,
That is, the effect of improving the oxidation resistance of the base metal powder is obtained, and in a laminated ceramic electronic component in which internal electrodes are formed using a conductive paste containing such a conductive powder, the conductive powder is oxidized by expansion. It is possible to suppress the occurrence of structural defects such as layer peeling at the time of debinding, the decrease in acquisition capacity due to insufficient sintering of conductive powder due to oxidation, the increase in equivalent series resistance and tan δ, and the like.

The average particle size of the base metal powder is 1.0 μm.
It is preferably m or less. Generally, as the average particle size of the base metal powder becomes smaller, the specific surface area increases and becomes active, so that oxidation easily occurs. In particular, when the average particle size of the base metal powder is 1.0 μm or less, oxidation tends to occur. Therefore, in the present invention, the oxidation resistance effect of the present invention is sufficiently exhibited when the average particle size of the base metal powder is 1.0 μm or less. The average particle size of the base metal powder is 1.
Although the oxidation resistance effect of the present invention can be obtained even when a powder having a particle size of more than 0 μm is used, the oxidation resistance effect is not so remarkable as that of the powder having a particle size of 1.0 μm or less because the specific surface area is originally small and it is not sensitive to oxidation. .

The average particle size of the Co-B alloy powder is 0.
It is preferably 10 μm or less and 1/2 or less of the average particle diameter of the base metal powder. If within the above range, C
The o-B alloy powder can coat the surface of the base metal powder more uniformly, and the oxidation resistance of the base metal powder can be sufficiently obtained.

Next, the conductive powder in one embodiment according to the present invention will be described in detail with reference to FIGS. 1 (a) and 1 (b). As shown in FIG. 1A, the conductive powder 1 includes a base metal powder 2, a Co-B alloy powder 3a,
Consists of.

The base metal powder 2 is, for example, Ni powder or Cu.
Powder, Ni-P alloy powder, Ni-Cr alloy powder, Cu-
Zn alloy powder, Ni powder with Pd powder attached, Ni powder with Ag attached, Ni powder with Pd-Ag alloy powder attached, Ni powder with Pt powder attached, Cu powder with Pd powder attached, Ag attached Examples thereof include Cu powder, Cu powder to which Pd-Ag alloy powder is attached, Cu powder to which Pt powder is attached, and the like, which are appropriately selected according to the ceramic characteristics of the laminated ceramic electronic component.

The Co-B alloy powder 3a is deposited on the surface of the base metal powder 2 and is smaller than the average particle size of the base metal powder 2, and the deposition amount is 50 parts by weight or less based on 100 parts by weight of the base metal powder. . Co-B constituting the conductive powder of the present invention
As a result of analyzing the alloy powder 3a, the alloy powder was amorphous, and the composition ratio of the B component contained in the alloy powder was about 25 mol%. The composition ratio of the B component contained in the Co-B alloy powder is not particularly limited.

Next, the case where heat is applied to the above-mentioned conductive powder 1 in one embodiment according to the present invention is shown in FIG.
A detailed description will be given based on (b). The heated conductive powder 1a is composed of the base metal powder 2 and the boron oxide film 3b.

The boron oxide film 3b is a Co-B alloy powder 3a.
After oxidizing the B component contained in (3), it is melted and left so as to substantially cover the surface of the base metal powder. C
In the o-B alloy powder 3a, when the temperature rises, the B component is first oxidized to boron oxide, and when the temperature further rises, the boron oxide melts. As described above, the boron oxide substantially covers the surface of the base metal powder to prevent the base metal powder from being oxidized. That is, the conductive paste containing the conductive powder in which the Co-B alloy powder is deposited on the surface of the base metal powder is in the paste as compared with the conductive paste in which the B powder or the B compound is added and dispersed. The Co-B alloy powder is uniformly dispersed in the powder, and the variation in the oxidation resistance of the base metal powder is reduced. Further, the presence of the Co-B alloy powder in the vicinity of the base metal powder increases the ratio of boron oxide coating the base metal powder, and the internal electrode is formed by using a conductive paste containing such conductive powder. In the formed multilayer ceramic electronic component, since the surface of the base metal powder is substantially covered with boron oxide in the firing step which is a manufacturing process thereof, the oxidation resistance of the base metal powder is enhanced.

Next, the conductive paste of the present invention will be described. The conductive paste of the present invention contains the above-mentioned conductive powder of the present invention and an organic vehicle. The material of the organic vehicle is not particularly limited, but is conventionally an organic vehicle that is generally used for a conductive paste suitable for forming internal electrodes of multilayer ceramic electronic components, specifically, an organic vehicle such as ethyl cellulose resin. It is possible to appropriately use a binder dissolved in a solvent such as terpineol.

Next, one embodiment of the monolithic ceramic electronic component of the present invention will be described in detail with reference to FIG. That is, the laminated ceramic electronic component 11 includes the ceramic laminated body 12, the internal electrodes 13 and 13, and the terminal electrode 1.
4, 14 and plated films 15, 15.

The ceramic laminated body 12 is formed by firing a raw ceramic laminated body in which a plurality of ceramic layers 12a made of a dielectric material containing BaTiO ₃ as a main component are laminated.

The internal electrodes 13, 13 are located between the ceramic layers 12a in the ceramic laminate 12, and the conductive paste of the present invention is printed on a plurality of raw ceramic layers 12a and laminated together with the raw ceramic layers. The internal electrodes 13, 1 are made by co-firing with the raw ceramic laminate.
The respective edges of 3 are formed so as to be exposed on either end surface of the ceramic laminate 12.

The conductive paste for forming the terminal electrodes is laminated on the ceramic so that the terminal electrodes 14, 14 are electrically and mechanically bonded to one end of the internal electrodes 13, 13 exposed on the end surface of the ceramic laminated body 12. It is applied to the end surface of the body 12 and baked.

The plating films 15 and 15 are made of, for example, Sn or N.
At least one layer is formed on the terminal electrodes 14, 14 by electroless plating such as i or solder plating.

The material of the ceramic laminated body 12 of the laminated ceramic electronic component of the present invention is not limited to the above-mentioned embodiment, and other dielectric materials such as PbZrO ₃ and insulators, magnetic bodies, semiconductors, etc. It does not matter if it is made of material. Further, the number of the internal electrodes 13 of the laminated ceramic electronic component of the present invention is not limited to the above-mentioned embodiment, and any number of layers may be formed. Further, the formation position and the number of terminal electrodes are not limited to those in the above-described embodiment. Further, the plating films 5 and 5 are not necessarily provided, and any number of layers may be formed.

[0036]

Example 1 First, Ni powder having an average particle size (0.5 μm or 1.0 μm) shown in Table 1 and a Co salt (CoSO ₄ .7H ₂ O) were dissolved in pure water. Of the Co-B alloy powder shown in Table 1 was prepared by adjusting the metal solution and a reducing solution obtained by dissolving sodium borohydride and sodium hydroxide in pure water, and adding the reducing solution to the metal solution. Samples 1 to 7 in which Co-B alloy powder was reduced and deposited on the surface of Ni powder so that the deposition amount and the average particle size were obtained, and this was thoroughly washed with pure water to deposit Co-B alloy powder.
Was obtained.

As a comparative example of three-liquid mixing, a Ni aqueous solution in which Ni powder having an average particle diameter of 0.5 μm is dispersed in pure water and a Co salt (CoSO ₄ .7H ₂ O) are dissolved in pure water. And a reducing solution prepared by dissolving sodium borohydride and sodium hydroxide in pure water.
At the same time, the metal solution and the reducing solution are added to the i aqueous solution,
Co-B alloy powder was reduced and precipitated on the surface of the i powder, and this was thoroughly washed with pure water to obtain a conductive powder of Sample 8 in which the Co-B alloy powder was precipitated.

As a comparative example of mixing two liquids, Ni powder having an average particle size of 0.5 μm and Co salt (CoSO ₄ .7H)
₂ O) in a pure water and a reducing solution in which pure sodium borohydride and sodium hydroxide are dissolved in pure water are prepared, and Ni powder is dispersed in the reducing solution. , A metal solution was added to the surface of the Ni powder to form Co-
The B alloy powder was reduced and precipitated, and was thoroughly washed with pure water to obtain a conductive powder of Sample 9 in which the Co—B alloy powder was precipitated.

As the conventional conductive powder, Ni powder having the average particle diameter shown in Table 1 was prepared, and this powder was used as samples 10-14.
Of conductive powder.

Therefore, the Ni containing the Co--B alloy powder is precipitated.
In order to confirm the oxidation resistance of the powder, samples 1-9, 13, 14
As for the oxidation start temperature of the conductive powder, the mass change from room temperature to 1000 ° C. in an air stream is measured using a differential thermal balance, and the temperature at which the weight increase due to the oxidation of the conductive powder starts is defined as the oxidation start temperature, This is summarized in Table 1. Regarding the conductive powders of Samples 10 to 12, after the conductive paste was prepared, it was dried and pulverized again, and the same measurement as that of Samples 1 to 9, 13 and 14 was performed using the differential thermal balance. This was summarized in Table 1.

[0041]

[Table 1]

As is clear from Table 1, the oxidation starting temperature of the conductive powder of Sample 2 obtained by adding the reducing solution containing the reducing agent to the metal solution containing the Ni powder and the Co salt is 355 ° C. The oxidation starting temperature of the conductive powder of Sample 8 obtained by simultaneously adding the metal solution containing the Co salt and the reducing solution containing the reducing agent to the aqueous solution containing the Ni powder was 315 ° C., and the reducing solution containing the Ni powder and the reducing agent contained Co. The oxidation starting temperature of the conductive powder of Sample 9 obtained by adding the metal solution containing salt was also 315 ° C.
It can be seen that the oxidation start temperature of the conductive powder is high. The conductive powders of Samples 2, 8 and 9 are the average particle diameter of Ni powder, Co-
The grain size ratio between the B alloy powder and the Ni powder, and the amount of the Co—B alloy powder deposited were 0.5 μm, 0.10, 1.
Since 0 wt% is common, the oxidation resistance efficiency of the conductive powder can be increased by the method of reaction deposition, that is, by adding a reducing solution containing a reducing agent to a metal solution containing Ni powder and Co salt. I understand.

In addition, the average particle diameter of the Ni powder was 0.5 μm, and Co-B alloy powder was deposited on the surface of Samples 1 to 1.
In the conductive powder of No. 5, the average particle size of Ni powder is 0.5 μm
m, and sample 13 in which Co-B alloy powder is not deposited
It can be seen that the oxidation starting temperature is shifted to a higher temperature than that of the conductive powder of No. 1 and the degree thereof is proportional to the amount of precipitation of the Co-B alloy powder.

The average particle size of the Ni powder is 0.5 μm,
Co-B alloy powder having an average particle diameter of 0.05 μm, Co-B
Conductive powders of Sample 1 and Sample 10, Sample 2 and Sample 11, Sample 3 and Sample 12 in which the amount of precipitation and the amount of addition of alloy powder are 0.1% by weight, 1.0% by weight and 10.0% by weight, respectively. Comparing these, the oxidation initiation temperatures were 325 ° C and 3 respectively.
It is 05 ° C., 355 ° C. and 310 ° C., 495 ° C. and 455 ° C., and it can be seen that the conductive powders of Samples 1 to 3 in which the Co—B alloy powder is deposited on the surface of the Ni powder are superior in oxidation resistance. .

Also, with respect to the conductive powder of Sample 7 in which the average particle diameter of the Ni powder was 1.0 μm and the Co-B alloy powder was deposited on the surface, the average particle diameter of the Ni powder was 1.
It is 0 μm, and it can be seen that the oxidation start temperature shifts toward a high temperature as compared with the conductive powder of Sample 14 in which the Co—B alloy powder is not precipitated. (Example 2) Next, a conductive paste was prepared using the conductive powders of Samples 1 to 14. That is, as shown in Table 2, after mixing 50% by weight of the conductive powder, 50% by weight of an organic vehicle obtained by mixing 20 parts by weight of an ethyl cellulose resin as an organic binder and 80 parts by weight of a terpineol as a solvent, Dispersion treatment was performed with three rolls to prepare conductive pastes of Samples 1 to 14. In addition,
Regarding the conductive pastes of Samples 10 to 12, 0.1% by weight, 1.0% by weight, and 1% by weight, respectively, were added during the above mixing.
Sample 1 was prepared by further adding 0.0 wt% Co-B alloy powder and mixing them at the same time, and then performing dispersion treatment with a three-roll mill.
The conductive paste was 0-12.

[0046]

[Table 2]

Then, the internal electrodes were formed using the conductive pastes of Samples 1 to 14, and the capacitance at the design stage was 2.
A multilayer ceramic capacitor of 0 μF is manufactured. That is, a ceramic layer containing BaTiO ₃ as a main component was prepared, and the conductivity of each of Samples 1 to 14 was adjusted so that one edge was exposed on the surface of a predetermined number of ceramic layers on either side of the ceramic layer. An electrode film to be an internal electrode was printed using a paste, and a predetermined number of these ceramic layers were laminated and pressure-bonded to prepare a plurality of raw ceramic laminates of Samples 1 to 14.

Next, in debinding the raw ceramic laminates of Samples 1 to 14, conditions were set as shown in Table 3. That is, in the case of a conductive paste using a conductive powder having no oxidation resistance, the conditions are that oxidation of the conductive powder is likely to occur: top temperature: 450 ° C., keep for 1 hour, Air
The atmosphere was set, and this was designated as binder removal condition A. On the other hand, although oxidation of the conductive powder is unlikely to occur, the top temperature of 30
It was set as 0 ° C., keep for 1 hour, and N ₂ atmosphere, and this was set as binder removal condition B.

[0049]

[Table 3]

Next, after the above binder removal treatment, firing is performed, and further, a conductive paste for forming a terminal electrode containing Ag as a conductive component is dip-coated on both end faces of the ceramic laminate,
Samples 1 to 1 provided with a pair of terminal electrodes electrically and mechanically bonded to internal electrodes after drying after baking
10,000 monolithic ceramic capacitors of No. 4 were obtained.

Therefore, first, the conductive pastes of Samples 1 to 14 were applied on a glass plate with a doctor blade to a thickness of 5 μm, dried at 100 ° C., and then applied with a stylus type film thickness meter. Ten-point surface roughness (Rz) was measured and summarized in Table 4. Next, 100 monolithic ceramic capacitors of Samples 1 to 14 were sampled one by one, and the capacitance (average of 100), short-circuit failure occurrence rate, and layer peeling failure occurrence rate were measured. 4 including Sa (Rz)
The items are comprehensively evaluated and summarized in Table 4.

The evaluation is that the capacitance is 2.0 ± 0.2.
μF, short-circuit failure occurrence rate 0%, layer peeling failure occurrence rate 0%, and surface roughness compared to the multilayer ceramic capacitors using the conductive powders of Samples 13 and 14 in which Co-B alloy powder was not deposited. Samples within the range of the present invention having substantially the same value are marked with a circle, and samples outside the range of the invention are marked with a circle.

[0053]

[Table 4]

As is apparent from Table 4, the average particle size of the Ni powder was measured by the reaction precipitation method of the present invention, which is a method of adding a reducing solution containing a reducing agent to a metal solution containing Ni powder and a Co salt. The multilayer ceramic capacitors using the conductive powders of Samples 1 to 4 and 7, in which 50 parts by weight or less of the Co-B alloy powder was deposited with respect to 100 parts by weight of Ni powder, had a capacitance of 1.8 to. 2.0 μF, the short-circuit defect occurrence rate and the layer peeling defect occurrence rate are both 0%,
Compared with the monolithic ceramic capacitors using the conductive powders of Samples 13 and 14 in which the Co-B alloy powder was not precipitated, the surface roughness was substantially equal to or lower than that of the monolithic ceramic capacitor, and thus it was within the scope of the present invention.

On the other hand, it is a comparative example of three-liquid mixing,
By the method of simultaneously adding the metal solution containing the Co salt and the reducing solution containing the reducing agent to the aqueous solution containing the Ni powder, the Co particle size is smaller than the average particle size of the Ni powder and is 50 parts by weight or less based on 100 parts by weight of the Ni powder. -Sample 8 in which B alloy powder was deposited
The multilayer ceramic capacitor using the conductive powder of No. 1 had a capacitance of 1.8 μF and a short circuit defect occurrence rate of 0%, but a layer peeling defect occurrence rate of 3% occurred. became.

Further, by the method of adding a metal solution containing a Co salt to a reducing solution containing Ni powder and a reducing agent, which is a comparative example of mixing two liquids, the average particle diameter of Ni powder is smaller than that of Ni powder.
50 parts by weight or less of Co-B based on 100 parts by weight of i powder
The multilayer ceramic capacitor using the conductive powder of Sample 9 in which the alloy powder was deposited had a capacitance of 1.8 μF,
Although the short-circuit failure occurrence rate was 0%, the layer peeling failure occurrence rate was 5%, which was outside the scope of the present invention.

Further, according to the reactive deposition method of the present invention, Ni
A multilayer ceramic capacitor using the conductive powder of Sample 5 in which 70 parts by weight of Co-B alloy powder was deposited with respect to 100 parts by weight of Ni powder, although the average particle size of the powder was smaller,
Since the capacitance was low at 0.9 μF and outside the allowable range,
It was outside the scope of the present invention.

Further, according to the reactive deposition method of the present invention, Ni
50 parts by weight or less of Co-B alloy powder was deposited with respect to 100 parts by weight of the powder, and the conductive powder of Sample 6 in which the average particle size of the Co-B alloy powder was equal to the average particle size of Ni powder was used. The multilayer ceramic capacitor used has an electrostatic capacity of 0.
It was out of the range of the present invention because the layer peeling defect occurrence rate was as high as 35%, which was low at 5 μF and out of the allowable range.

The multilayer ceramic capacitors of Samples 10 to 12 in which the Co--B alloy powder was added to the conductive paste had a low capacitance of 1.4 μF, which was outside the allowable range.
The rate of defective layer peeling was 25 to 35%, which was inferior.

Samples 13 and 1 which are conventional Ni powders
Samples 13A, 13B, 14A, 1 using the conductive powder of No. 4
In the 4B multilayer ceramic capacitor, when the binder removal condition is high in the air atmosphere and the top temperature is high, the electrostatic capacitance becomes extremely low and the layer peeling defect occurrence rate increases.
It can be seen that when the top temperature is low in the N ₂ atmosphere, the short-circuit defect occurrence rate becomes high.

[0061]

As described above, according to the present invention, at least one base metal powder selected from the group consisting of Ni powder, Cu powder, alloy powder containing Ni or / and Cu as a main component, and Co salt are used. A reducing solution containing a borohydride or / and an amine borane is added to and mixed with the metal solution containing the base metal powder, and the surface of the base metal powder is smaller than the average particle size of the base metal powder. It is possible to provide a conductive powder having oxidation resistance and a conductive paste using such a conductive powder by precipitating Co-B alloy powder in an amount of 1 part or less, and to decompose and remove organic substances. It is possible to remove the binder in an oxidizing atmosphere at a sufficient temperature, and the yield and yield of multilayer ceramic electronic components that form internal electrodes using such a conductive paste. Thereby improving the productivity.

The average particle size of the above base metal powder is
Since the base metal powder is characterized by having a particle size of 1.0 μm or less, generally, the smaller the particle size, the larger the specific surface area of the base metal powder, which becomes active and becomes more susceptible to oxidation, but the base metal powder is improved in oxidation resistance. The effect of the invention becomes remarkable,
Further, there is an effect that it can contribute to further thinning and multilayering of the monolithic ceramic electronic component.

The average particle size of the Co-B alloy powder is 0.1 μm or less, and is 1/2 or less of the average particle size of the base metal powder.
The alloy powder has an effect that the surface of the base metal powder can be coated more uniformly and the oxidation resistance of the base metal powder can be sufficiently obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conductive powder according to one embodiment of the present invention, (a) is an explanatory view of a state in which a Co—B alloy powder is deposited on the surface of a base metal powder, and (b) is an oxide. It is explanatory drawing of the state in which the surface of the base metal powder was substantially covered with boron.

FIG. 2 is a cross-sectional view of a monolithic ceramic electronic component according to an embodiment of the present invention.

[Explanation of symbols]

1 Conductive powder 2 Base metal powder 3a Co-B alloy powder 11 Multilayer ceramic electronic components 12a ceramic layer 12 Ceramic laminate 13 internal electrodes

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01B 1/00 H01B 1/00 L 1/22 1/22 A 13/00 501 13/00 501Z H01G 4/12 361 H01G 4/12 361 4/30 311 4/30 311Z F term (reference) 4K017 AA02 BA03 BA05 BB06 DA07 DA08 EA03 4K018 BA02 BA04 BC01 BC22 BD04 5E001 AB03 AH01 AJ01 5E082 AB03 EE31 5G301 DA02 DA06 DA10 DD01 DE03

Claims (8)

[Claims] 1. A metal solution containing at least one base metal powder selected from the group consisting of Ni powder, Cu powder, Ni or / and alloy powder containing Cu and / or Cu as a main component, and a borohydride or a metal salt. And / or a reducing solution containing amine borane is added and mixed, and the average particle size of the base metal powder is smaller than the average particle size of the base metal powder on the surface of the base metal powder.
A method for producing a conductive powder, which comprises depositing Co-B alloy powder by weight or less. 2. The conductive material according to claim 1, further comprising a heat treatment step of heat-treating the base metal powder having the Co—B alloy powder deposited on the surface thereof at 100 ° C. or higher after the precipitation step. Powder manufacturing method. 3. The conductive powder according to claim 1, further comprising a crushing step of crushing the base metal powder having the Co-B alloy powder deposited on the surface after the depositing step. Manufacturing method. 4. The average particle size of the base metal powder is 1.0 μm.
It is m or less, The manufacturing method of the electrically conductive powder in any one of Claims 1-3 characterized by the above-mentioned. 5. The average particle diameter of the Co—B alloy powder is
It is 0.1 micrometer or less, and is 1/2 or less of the average particle diameter of the said base metal powder, The manufacturing method of the electrically conductive powder in any one of Claims 1-4 characterized by the above-mentioned. 6. A conductive powder obtained by the manufacturing method according to any one of claims 1 to 5. 7. A conductive paste containing the conductive powder according to claim 6 and an organic vehicle. 8. A monolithic ceramic electronic component comprising: a ceramic laminated body formed by laminating a plurality of ceramic layers; and a plurality of internal electrodes formed between the ceramic layers, wherein the internal electrodes are A multilayer ceramic electronic component, characterized by being formed using the conductive paste according to (4).