JP2002146401A - Nickel powder and manufacturing method - Google Patents
Nickel powder and manufacturing methodInfo
- Publication number
- JP2002146401A JP2002146401A JP2000341649A JP2000341649A JP2002146401A JP 2002146401 A JP2002146401 A JP 2002146401A JP 2000341649 A JP2000341649 A JP 2000341649A JP 2000341649 A JP2000341649 A JP 2000341649A JP 2002146401 A JP2002146401 A JP 2002146401A
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- Japan
- Prior art keywords
- nickel powder
- particles
- nickel
- less
- alkaline earth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明はニッケル粉及びその
製造方法に関し、より詳しくは、導電ペースト用途に特
に適しており、ニッケル粉の粒度分布がシャープである
ことに起因して積層セラミックコンデンサの薄くて突起
がない内部電極を形成することができ且つニッケル粒子
内の平均結晶子径が大きいことに起因して熱収縮が抑制
された内部電極を形成することができるニッケル粉及び
その製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel powder and a method for producing the same, and more particularly, to a nickel powder and a method for producing the same. The present invention relates to a nickel powder capable of forming an internal electrode having no projections and capable of forming an internal electrode in which thermal shrinkage is suppressed due to a large average crystallite diameter in nickel particles, and a method for producing the same.
【０００２】また、本発明は、導電ペースト用途に特に
適しており、凝集が少なく単分散状態に近いことに起因
して導電ペーストの製造の際の有機ビヒクル中での分散
性が優れており且つニッケル粒子内の平均結晶子径が大
きいことに起因して熱収縮が抑制された内部電極を形成
することができるニッケル粉及びその製造方法に関す
る。Further, the present invention is particularly suitable for use in conductive pastes, and has excellent dispersibility in an organic vehicle in the production of conductive pastes due to little aggregation and close to a monodispersed state. The present invention relates to a nickel powder capable of forming an internal electrode in which thermal shrinkage is suppressed due to a large average crystallite diameter in nickel particles, and a method for producing the same.
【０００３】[0003]
【従来の技術】積層セラミックコンデンサは交互に積層
された複数のセラミック誘電体層と内部電極層とが一体
化したものであり、このような積層セラミックコンデン
サの内部電極を形成させる方法としては、内部電極材料
である金属微粉末をペースト化して導電ペーストを調製
し、該導電ペーストを用いてセラミック誘電体グリーン
シート上に印刷し、このセラミック誘電体グリーンシー
トと導体ペースト層とを交互に層状に複数層積層し、加
熱圧着して一体化させた後、還元性雰囲気中、高温で焼
成してセラミック誘電体層と内部電極層とを一体化させ
ることが一般的である。2. Description of the Related Art A multilayer ceramic capacitor has a structure in which a plurality of ceramic dielectric layers alternately stacked and an internal electrode layer are integrated with each other. A conductive paste is prepared by forming a metal fine powder as an electrode material into a paste, and is printed on a ceramic dielectric green sheet using the conductive paste, and the ceramic dielectric green sheet and the conductive paste layer are alternately layered in a plurality of layers. It is general that the layers are laminated, heat-pressed and integrated, and then fired at a high temperature in a reducing atmosphere to integrate the ceramic dielectric layer and the internal electrode layer.
【０００４】この内部電極材料として、従来は白金、パ
ラジウム、銀−パラジウム等の貴金属が使用されていた
が、コスト低減のために、近時にはこれらの貴金属の代
わりにニッケル等の卑金属を用いる技術が開発され、進
歩してきている。また、一般的には、積層セラミックコ
ンデンサの内部電極を形成するのに用いる導電ペースト
は、導電性を付与するニッケル粉等の金属粉の他に、必
要に応じてガラス物質等の無機材料やその他の添加剤を
有機ビヒクル中に添加し、均一に混合、分散させて製造
される。Conventionally, noble metals such as platinum, palladium, and silver-palladium have been used as the internal electrode material. However, in order to reduce costs, a technique using a base metal such as nickel instead of these noble metals has recently been used. Developed and evolving. In general, the conductive paste used to form the internal electrodes of the multilayer ceramic capacitor is not only a metal powder such as a nickel powder that imparts conductivity, but also an inorganic material such as a glass material or the like, if necessary. Is added to an organic vehicle and uniformly mixed and dispersed.
【０００５】近年、導電ペーストを用いて製造される電
子部品、例えば積層セラミックコンデンサ等はますます
小型化しており、それで、必然的に、セラミック誘電体
層及び内部電極層の薄膜化、多層化が進み、現在積層部
品、特に積層セラミックコンデンサでは誘電体層２μｍ
以下、内部電極膜厚１．５μｍ以下、積層数１００層以
上の部品が作られている。In recent years, electronic components manufactured using conductive pastes, for example, multilayer ceramic capacitors and the like have been increasingly miniaturized. Therefore, it is inevitable that ceramic dielectric layers and internal electrode layers are made thinner and multilayered. Now, multilayer parts, especially multilayer ceramic capacitors, have a dielectric layer of 2 μm
Hereinafter, components having an internal electrode film thickness of 1.5 μm or less and a lamination number of 100 or more are manufactured.
【０００６】薄い内部電極層を得るためにはそれに見合
った平均粒子径の小さい金属粉、例えばニッケル粉を用
いればよいと考えられるが、金属粉の平均粒子径が所定
の範囲内にあっても粗粒子が混入していると、そのよう
な金属粉を含む導電ペーストを用いて内部電極層を形成
すると、その粗粒子が内部電極層上に突起を形成し、そ
の突起が薄いセラミック誘電体層を突き破って内部電極
間の短絡を引き起こすことがある。このような内部電極
間の短絡を防止するためには、薄い内部電極層を得るの
に見合った平均粒子径のニッケル粉よりもかなり小さい
平均粒子径のニッケル粉を用いる必要がある。To obtain a thin internal electrode layer, it is considered appropriate to use a metal powder having a small average particle size, for example, a nickel powder. However, even if the average particle size of the metal powder is within a predetermined range, it is considered appropriate. When coarse particles are mixed, when the internal electrode layer is formed using a conductive paste containing such metal powder, the coarse particles form projections on the internal electrode layer, and the projections are thin ceramic dielectric layers. May cause a short circuit between the internal electrodes. In order to prevent such a short circuit between the internal electrodes, it is necessary to use a nickel powder having an average particle diameter considerably smaller than a nickel powder having an average particle diameter suitable for obtaining a thin internal electrode layer.
【０００７】また、特に積層セラミックコンデンサの内
部電極を形成するのに用いる導電ペーストの用途のニッ
ケル粉においては、ニッケル粉の有機ビヒクル中への分
散性は、形成される内部電極の善し悪しに多大な影響を
及ぼす。即ち、分散性が悪いニッケル粉を用いて得た導
電ペーストでは、当然導電ペースト中に凝集粉が残留し
てしまうので、そのような導電ペーストを用いて内部電
極を形成すると内部電極層上に凹凸が生じたり、隣接す
る内部電極間で短絡が生じたりするという不具合が起き
やすい。従って、導電ペースト中でのニッケル粉の分散
性については、有機ビヒクル中へのニッケル粉の分散性
が高いことが重要である。In particular, in nickel powder for use as a conductive paste used to form internal electrodes of a multilayer ceramic capacitor, the dispersibility of nickel powder in an organic vehicle depends on the quality of the formed internal electrodes. affect. That is, in a conductive paste obtained using nickel powder having poor dispersibility, agglomerated powder naturally remains in the conductive paste. Therefore, when an internal electrode is formed using such a conductive paste, irregularities are formed on the internal electrode layer. Or a short-circuit occurs between adjacent internal electrodes. Therefore, regarding the dispersibility of the nickel powder in the conductive paste, it is important that the nickel powder be highly dispersible in the organic vehicle.
【０００８】ニッケル粉は湿式法、乾式法の何れの方法
によっても製造可能である。液相還元析出法に代表され
る湿式法の場合には、粒度分布がシャープなニッケル粉
が容易に得られる。そのような製法で得られたニッケル
粉を導電ペースト化し、得られた導電ペーストを用いて
積層セラミックコンデンサの内部電極を形成させた場合
には、粗粉の混入が少ないので内部電極層上に突起が形
成されることがほとんどなく、従って、内部電極間の短
絡が発生することはほとんどない。しかし、この湿式法
により得られるニッケル粉の粒子形状は多面体形状を呈
する場合が多いので、粒子間の凝集や粉末の流動性の面
で劣っている。[0008] Nickel powder can be produced by any of a wet method and a dry method. In the case of a wet method typified by a liquid phase reduction precipitation method, a nickel powder having a sharp particle size distribution can be easily obtained. When the nickel powder obtained by such a manufacturing method is converted into a conductive paste, and the obtained conductive paste is used to form the internal electrodes of the multilayer ceramic capacitor, projections on the internal electrode layers are reduced because coarse powder is little mixed. Are rarely formed, and therefore, a short circuit between the internal electrodes hardly occurs. However, the particle shape of the nickel powder obtained by this wet method often exhibits a polyhedral shape, and thus is inferior in terms of agglomeration between particles and fluidity of the powder.
【０００９】一方、気相還元法に代表される乾式法の場
合には、粒子間の凝集や粉末の流動性の面では良好なニ
ッケル粉が得易いものの、例えば特開平１１−８０８１
７号公報に記載されているように、粒子形状を制御する
ために硫黄等の添加を必要とする。また、そのような製
法で得られたニッケル粉を導電ペースト化し、得られた
導電ペーストを用いて積層セラミックコンデンサの内部
電極を形成させた場合には、内部電極にボイド（膨れ）
等の発生が生じる他に、粒度分布がブロードであること
に起因して前記したような粗粉による悪影響や分散性へ
の影響も免れない。On the other hand, in the case of a dry method typified by a gas phase reduction method, good nickel powder can be easily obtained in terms of agglomeration between particles and fluidity of the powder.
As described in Japanese Patent Publication No. 7, the addition of sulfur or the like is required to control the particle shape. In addition, when the nickel powder obtained by such a manufacturing method is converted into a conductive paste, and the obtained conductive paste is used to form the internal electrodes of the multilayer ceramic capacitor, voids (swelling) occur in the internal electrodes.
In addition to the occurrence of such a problem, the above-mentioned adverse effects of coarse powder and the influence on dispersibility due to the broad particle size distribution are inevitable.
【００１０】以上に述べたように、従来技術においては
粒度分布がよりシャープで、凝集がより少なく且つ分散
性に優れたニッケル粉を得ることは困難であった。ま
た、積層セラミックコンデンサの内部電極材料としてニ
ッケル粉を用いる場合には、セラミック基材と金属ニッ
ケルとの熱収縮特性の相違に起因して、焼成の際にデラ
ミネーションやクラック等の欠陥が発生し易いので、こ
のニッケル粉の熱収縮も抑制する必要がある。As described above, in the prior art, it has been difficult to obtain a nickel powder having a sharper particle size distribution, less aggregation and excellent dispersibility. Further, when nickel powder is used as the internal electrode material of the multilayer ceramic capacitor, defects such as delamination and cracks occur during firing due to the difference in heat shrinkage characteristics between the ceramic substrate and metallic nickel. Therefore, it is necessary to suppress the heat shrinkage of the nickel powder.
【００１１】以上に述べた従来のニッケル粉の問題点を
改善する技術、即ち粒度分布がよりシャープで、凝集が
より少なくて分散性に優れ、且つ熱収縮特性にも優れた
ニッケル粉を得る技術については、例えば、特開平８−
２４６００１号公報に記載の技術を挙げることができ
る。該公報には、平均粒子径が０．１〜１．０μｍの範
囲で個数基準の粒度分布における５０％粒子径（Ｄ50）
と積算ふるい下８４．３％粒子径（Ｄ84.3）との比（Ｄ
84.3／Ｄ50）で求められた幾何標準偏差が２．０以下
で、平均結晶子径が平均粒子径の０．２倍以上であるニ
ッケル超微粉が開示されている。A technique for solving the problems of the conventional nickel powder described above, that is, a technique for obtaining a nickel powder having a sharper particle size distribution, less aggregation, excellent dispersibility, and excellent heat shrinkage characteristics. Regarding, for example,
The technique described in Japanese Patent Publication No. 246001 can be mentioned. The publication discloses a 50% particle size (D 50 ) in a number-based particle size distribution with an average particle size in the range of 0.1 to 1.0 μm.
And the ratio (D 84.3 ) of the 84.3% particle size (D 84.3 )
84.3 / D 50 ) discloses a nickel ultrafine powder having a geometric standard deviation of 2.0 or less and an average crystallite size of 0.2 times or more the average particle size.
【００１２】このニッケル超微粉は、凝集したニッケル
粉が少ないという点で粒度分布に優れ、平均結晶子径が
比較的大きく、金属ニッケルの過焼結が抑制されること
から熱収縮特性に優れているものの、ニッケル粉の一次
粒子に関する粒度分布、特に微粉の粒度については何ら
改善がなされていないので、上記の問題点を充分に解決
し得る技術とは言い難い。The ultrafine nickel powder has an excellent particle size distribution in that the amount of agglomerated nickel powder is small, has a relatively large average crystallite diameter, and has excellent heat shrinkage characteristics because of suppressing oversintering of metallic nickel. However, since the particle size distribution of the primary particles of the nickel powder, particularly the particle size of the fine powder, has not been improved at all, it cannot be said that the technology can sufficiently solve the above problems.
【００１３】また、熱収縮特性を改善する技術として、
塩化ニッケル粉からなる原料粉末を、特定のアルカリ金
属又は特定のアルカリ土類金属からなる還元剤粉体と、
これらのアルカリ金属塩化物又は特定のアルカリ土類金
属塩化物の粉粒体とに混合して固相還元する微細ニッケ
ル粉の製造方法（特開平１１−２３６６３１号公報）等
も開示されている。この製造方法においては、結晶性や
分散性に優れたニッケル粉が得られると記載されてい
る。As a technique for improving the heat shrinkage property,
A raw material powder composed of nickel chloride powder, a reducing agent powder composed of a specific alkali metal or a specific alkaline earth metal,
Also disclosed is a method for producing fine nickel powder which is mixed with powders of these alkali metal chlorides or specific alkaline earth metal chlorides and solid-phase reduced (Japanese Patent Application Laid-Open No. 11-236631). In this production method, it is described that a nickel powder excellent in crystallinity and dispersibility can be obtained.
【００１４】しかしながら、上記の製造方法により得ら
れるニッケル粉では、熱収縮特性はある程度改善される
ものの、出発原料がニッケル塩であることにより還元速
度の制御が困難であるのみならず、粒度分布がよりシャ
ープで、凝集がより少なくて分散性に優れたニッケル粉
とは言い難かった。[0014] However, in the nickel powder obtained by the above-mentioned production method, although the heat shrinkage property is improved to some extent, the control of the reduction rate is difficult because the starting material is a nickel salt, and the particle size distribution is also difficult. It was hard to say that the nickel powder was sharper, had less aggregation, and had excellent dispersibility.
【００１５】[0015]
【発明が解決しようとする課題】本発明は、上記した従
来技術の問題点に鑑み、積層セラミックコンデンサの薄
くて突起がなく、熱収縮が抑制された内部電極の形成に
用いる導電ペースト用途に特に適しているニッケル粉及
びその製造方法を提供すること、並びに導電ペーストの
製造の際の有機ビヒクル中での分散性が優れており、熱
収縮が抑制された内部電極の形成に用いる導電ペースト
用途に特に適したニッケル粉及びその製造方法を提供す
ることを課題としている。SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention is particularly applicable to a conductive paste used for forming an internal electrode of a multilayer ceramic capacitor which is thin, has no protrusions, and has reduced heat shrinkage. Providing a suitable nickel powder and a method for producing the same, and a conductive paste used for forming an internal electrode having excellent dispersibility in an organic vehicle at the time of producing a conductive paste and suppressing heat shrinkage. It is an object of the present invention to provide a particularly suitable nickel powder and a method for producing the same.
【００１６】[0016]
【課題を解決するための手段】本発明者等は上記の課題
を達成するために鋭意検討した結果、粒度分布がシャー
プであり且つニッケル粒子内の平均結晶子径が大きいニ
ッケル粉は積層セラミックコンデンサの薄くて突起がな
く、熱収縮が抑制され内部電極の形成に用いる導電ペー
スト用途に特に適しており、又凝集が少なくて単分散状
態に近く且つニッケル粒子内の平均結晶子径が大きいニ
ッケル粉は導電ペーストの製造の際の有機ビヒクル中で
の分散性が優れており、熱収縮が抑制された内部電極の
形成に用いる導電ペースト用途に特に適していることを
見いだし、発明を完成した。Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, it has been found that nickel powder having a sharp particle size distribution and a large average crystallite size in nickel particles is a multilayer ceramic capacitor. Nickel powder that is thin, has no protrusions, suppresses heat shrinkage, is particularly suitable for use as a conductive paste used for forming internal electrodes, has low aggregation, is close to a monodispersed state, and has a large average crystallite diameter in nickel particles. Have excellent dispersibility in an organic vehicle in the production of a conductive paste and have been found to be particularly suitable for use in a conductive paste used for forming an internal electrode with reduced heat shrinkage, and have completed the invention.
【００１７】即ち、本発明のニッケル粉は、ＳＥＭ観察
による平均粒子径の１．２倍以上の粒子径を持つ粒子個
数が全粒子個数の１０％以下であり、該平均粒子径の
０．８倍以下の粒子径を持つ粒子個数が全粒子個数の１
０％以下であり、且つニッケル粒子内の平均結晶子径が
４００Å以上であることを特徴とする。That is, in the nickel powder of the present invention, the number of particles having a particle diameter of 1.2 times or more the average particle diameter by SEM observation is 10% or less of the total number of particles, and the average particle diameter is 0.8% or less. The number of particles having a particle diameter of twice or less is 1 of the total number of particles.
0% or less, and the average crystallite size in the nickel particles is 400 ° or more.
【００１８】また、本発明のニッケル粉は、レーザ回折
散乱式粒度分布測定による平均粒子径（Ｄ50値）の１．
５倍以上の粒子径を持つ粒子個数が全粒子個数の２０％
以下であり、該平均粒子径（Ｄ50値）の０．５倍以下の
粒子径を持つ粒子個数が全粒子個数の５％以下であり、
且つニッケル粒子内の平均結晶子径が４００Å以上であ
ることを特徴とする。Further, the nickel powder of the present invention, the first average particle diameter measured by a laser diffraction scattering particle size distribution measurement (D 50 value).
20% of the total number of particles with a particle diameter of 5 times or more
Or less, and the number of particles having a particle diameter of 0.5 times or less of the average particle diameter (D 50 value) is 5% or less of the total number of particles,
In addition, the average crystallite diameter in the nickel particles is 400 ° or more.
【００１９】また、本発明のニッケル粉の製造方法は、
ニッケル粉とアルカリ土類金属の酸化物、水酸化物、炭
酸塩及び炭酸水素塩よりなる群から選ばれたアルカリ土
類金属化合物の微粉末とを混合した後、またはニッケル
粉の各粒子表面に該アルカリ土類金属化合物を被覆させ
た後、不活性ガス又は微還元性ガス雰囲気中で、該アル
カリ土類金属化合物の溶融温度未満の温度で熱処理を実
施することを特徴とする。Further, the method for producing nickel powder of the present invention comprises:
After mixing nickel powder and fine powder of alkaline earth metal compound selected from the group consisting of oxides, hydroxides, carbonates and bicarbonates of alkaline earth metals, or on the surface of each particle of nickel powder After coating the alkaline earth metal compound, a heat treatment is performed in an atmosphere of an inert gas or a slightly reducing gas at a temperature lower than the melting temperature of the alkaline earth metal compound.
【００２０】[0020]
【発明の実施の形態】本発明のニッケル粉においては、
１万倍程度のＳＥＭ観察による平均粒子径の１．２倍以
上の粒子径を持つ粒子個数が全粒子個数の１０％以下、
好ましくは７％以下、より好ましくは５％以下であり、
該平均粒子径の０．８倍以下の粒子径を持つ粒子個数が
全粒子個数の１０％以下、好ましくは７％以下、より好
ましくは５％以下であることが重要である。BEST MODE FOR CARRYING OUT THE INVENTION In the nickel powder of the present invention,
The number of particles having a particle diameter of 1.2 times or more of the average particle diameter by SEM observation of about 10,000 times is 10% or less of the total number of particles,
Preferably at most 7%, more preferably at most 5%,
It is important that the number of particles having a particle diameter of 0.8 times or less of the average particle diameter is 10% or less, preferably 7% or less, more preferably 5% or less of the total number of particles.
【００２１】即ち、本発明のニッケル粉においては、粗
粒の割合が比較的小さく、ニッケル粉中の各ニッケル粒
子の粒子径が相当に均一であるので、そのようなニッケ
ル粉を含む導電ペーストを用いて得られる積層部品例え
ば積層セラミックコンデンサにおいては、ニッケル粉の
平均粒子径に比較してかなり薄い内部電極層を形成する
ことができ、しかも内部電極層の表面に突起が形成され
ることはなく、従って内部電極間の短絡が起こることが
ない。更に、微細粒の割合も比較的小さいので、そのよ
うなニッケル粉を含む導電ペーストの粘度が上昇すると
いう問題が発生せず、また熱焼結が均一に起こるので電
極面積が減少したり、電極が消失したりすることもな
い。That is, in the nickel powder of the present invention, the proportion of coarse particles is relatively small, and the particle diameter of each nickel particle in the nickel powder is considerably uniform. In a multilayer component obtained by using, for example, a multilayer ceramic capacitor, an internal electrode layer that is considerably thinner than the average particle size of nickel powder can be formed, and furthermore, no projection is formed on the surface of the internal electrode layer. Therefore, no short circuit occurs between the internal electrodes. Further, since the ratio of the fine particles is relatively small, the problem that the viscosity of the conductive paste containing nickel powder increases does not occur, and since the heat sintering occurs uniformly, the electrode area decreases, Does not disappear.
【００２２】また、本発明のニッケル粉においては、上
記の条件に加えて、ニッケル粒子内の平均結晶子径が４
００Å以上であること、好ましくは４５０Å以上である
ことが重要である。即ち、本発明のニッケル粉は平均結
晶子径が大きいことにより、結晶性が改善されており、
従って積層セラミックコンデンサを製造する際の焼成時
において、過焼結による収縮を抑制することができる。Further, in the nickel powder of the present invention, in addition to the above conditions, the average crystallite diameter in the nickel particles is 4
It is important that it is not less than 00 °, preferably not less than 450 °. That is, the nickel powder of the present invention has improved crystallinity due to a large average crystallite diameter,
Therefore, shrinkage due to oversintering can be suppressed during firing when manufacturing a multilayer ceramic capacitor.
【００２３】更に、本発明のニッケル粉においては、レ
ーザ回折散乱式粒度分布測定による平均粒子径（Ｄ
50値）の１．５倍以上の粒子径を持つ粒子個数が全粒子
個数の２０％以下、好ましくは１５％以下、より好まし
くは１０％以下であり、平均粒子径（Ｄ50値）の０．５
倍以下の粒子径を持つ粒子個数が全粒子個数の５％以
下、好ましくは３％以下、より好ましくは１％以下であ
る。Further, in the nickel powder of the present invention, the average particle size (D
The number of particles having a particle diameter of 1.5 times or more of ( 50 value) is 20% or less, preferably 15% or less, more preferably 10% or less of the total number of particles, and is 0% of the average particle diameter (D50 value). .5
The number of particles having a particle diameter of twice or less is 5% or less, preferably 3% or less, more preferably 1% or less of the total number of particles.
【００２４】このような粒度分布を有するニッケル粉で
あれば、ニッケル粉の各粒子間の凝集が抑制されている
ので、導電ペーストの製造時において有機ビヒクル中へ
の分散性に優れている。また、このニッケル粉において
は、上記の条件に加えて、ニッケル粒子内の平均結晶子
径が４００Å以上であること、好ましくは４５０Å以上
であることが重要である。その理由は上記した通りであ
る。The nickel powder having such a particle size distribution is excellent in dispersibility in an organic vehicle during the production of a conductive paste because the aggregation between the particles of the nickel powder is suppressed. Further, in addition to the above conditions, it is important that the average crystallite diameter in the nickel particles is 400 ° or more, preferably 450 ° or more. The reason is as described above.
【００２５】また、本発明のニッケル粉においては、下
記の式（１）により求められる変動係数（ＣＶ）が好ま
しくは４０％未満、より好ましくは３５％未満、最も好
ましくは３０％未満である。In the nickel powder of the present invention, the coefficient of variation (CV) determined by the following equation (1) is preferably less than 40%, more preferably less than 35%, and most preferably less than 30%.
【００２６】[0026]
【数２】 (Equation 2)
【００２７】このような変動係数を有するニッケル粉を
含む導電ペーストを用いて積層セラミックコンデンサの
内部電極を形成する場合には、上記のような粒度分布を
有するニッケル粉を含む導電ペーストを用いて積層セラ
ミックコンデンサの内部電極を形成する場合と同等、又
はそれ以上の薄層化、高容量化が達成できる。In the case where the internal electrodes of the multilayer ceramic capacitor are formed using the conductive paste containing nickel powder having such a coefficient of variation, the conductive paste containing nickel powder having the above-mentioned particle size distribution is used. It is possible to achieve a thinner and higher capacity equivalent to or more than the case where the internal electrodes of the ceramic capacitor are formed.
【００２８】導電ペーストに用いるニッケル粉中のアル
カリ金属の含有量が高い場合には、例えば、導電ペース
ト中のニッケル粉を加熱溶融させて積層セラミックコン
デンサの内部電極を形成する際に、アルカリ金属が金属
ニッケル表面に析出し、またそのアルカリ金属不純物が
電解質成分であるので、近隣の電極間で導通が生じ、遂
には絶縁破壊を生じせしめることがある。When the content of the alkali metal in the nickel powder used for the conductive paste is high, for example, when the nickel powder in the conductive paste is heated and melted to form the internal electrodes of the multilayer ceramic capacitor, the alkali metal may be removed. Since it is deposited on the surface of metallic nickel and the alkali metal impurity is an electrolyte component, conduction occurs between neighboring electrodes, and eventually dielectric breakdown may occur.
【００２９】従って、本発明のニッケル粉においては、
ニッケル粉中のアルカリ金属の総量、特にリチウム、ナ
トリウム及びカリウムの１種又は２種以上の合計量はな
るべく低い方が好ましく、総量が５００ｐｐｍ以下であ
ることが好ましく、４００ｐｐｍ以下であることがより
好ましく、３００ｐｐｍ以下であることが一層好まし
い。Therefore, in the nickel powder of the present invention,
The total amount of alkali metals in the nickel powder, particularly the total amount of one or more of lithium, sodium and potassium, is preferably as low as possible, and the total amount is preferably 500 ppm or less, more preferably 400 ppm or less. , 300 ppm or less.
【００３０】導電ペーストに用いるニッケル粉中の塩素
の含有量が高い場合には、この塩素不純物が電解質成分
であるので、上記のアルカリ金属の場合と同様に絶縁破
壊が生じることがある。従って、本発明のニッケル粉に
おいては、ニッケル粉中の塩素含有量はなるべく低い方
が好ましく、１００ｐｐｍ以下であることが好ましく、
５０ｐｐｍ以下であることがより好ましく、１０ｐｐｍ
以下であることが一層好ましい。When the content of chlorine in the nickel powder used for the conductive paste is high, the chlorine impurity is an electrolyte component, so that dielectric breakdown may occur as in the case of the alkali metal. Therefore, in the nickel powder of the present invention, the chlorine content in the nickel powder is preferably as low as possible, preferably 100 ppm or less,
More preferably 50 ppm or less, 10 ppm
It is more preferred that:
【００３１】導電ペーストに用いるニッケル粉中の硫黄
の含有量が高い場合には、積層セラミックコンデンサ製
造時の焼成の際に、この硫黄成分が酸素と反応して亜硫
酸ガスを発生してボイド（膨れ）を惹き起こすのみなら
ず、この硫黄成分が誘電体成分と反応し、その硫化物は
半導体としての挙動を示すので、絶縁特性が著しく劣化
する。If the sulfur content in the nickel powder used for the conductive paste is high, the sulfur component reacts with oxygen to generate sulfurous acid gas during firing during the production of the multilayer ceramic capacitor, resulting in voids (swelling). ), The sulfur component reacts with the dielectric component, and the sulfide exhibits the behavior as a semiconductor, so that the insulating property is significantly deteriorated.
【００３２】従って、本発明のニッケル粉においては、
ニッケル粉中の硫黄含有量はなるべく低い方が好まし
く、１００００ｐｐｍ以下であることが好ましく、１０
００ｐｐｍ以下であることがより好ましく、２００ｐｐ
ｍ以下であることが一層好ましい。Therefore, in the nickel powder of the present invention,
The sulfur content in the nickel powder is preferably as low as possible, more preferably 10,000 ppm or less, and
More preferably, it is 200 ppm or less.
m or less.
【００３３】また、本発明のニッケル粉は、ＳＥＭ観察
による平均粒子径が０．０５〜１μｍであることが好ま
しく、０．１〜０．８μｍであることが一層好ましい。
このようなニッケル粉を含む導電ペーストは積層セラミ
ックコンデンサの内部電極を形成するのに特に適してい
る。なお、本発明のニッケル粉は純ニッケル粉であって
も、ニッケル粉の各微粒子の内部に金属酸化物を含有す
るニッケル粉であってもよい。The nickel powder of the present invention preferably has an average particle size of 0.05 to 1 μm, more preferably 0.1 to 0.8 μm, as observed by SEM.
Such a conductive paste containing nickel powder is particularly suitable for forming internal electrodes of a multilayer ceramic capacitor. The nickel powder of the present invention may be pure nickel powder or nickel powder containing a metal oxide inside each fine particle of the nickel powder.
【００３４】次に、本発明のニッケル粉の製造方法につ
いて述べる。本発明の製造方法は、ニッケル粉とアルカ
リ土類金属の酸化物、水酸化物、炭酸塩及び炭酸水素塩
よりなる群から選ばれたアルカリ土類金属化合物の微粉
末とを混合した後、またはニッケル粉の各粒子表面に該
アルカリ土類金属化合物を被覆させた後、不活性ガス又
は微還元性ガス雰囲気中で、該アルカリ土類金属化合物
の溶融温度未満の温度で熱処理を実施することを特徴と
する。Next, the method for producing nickel powder of the present invention will be described. The production method of the present invention, after mixing nickel powder and fine powder of an alkaline earth metal compound selected from the group consisting of oxides, hydroxides, carbonates and bicarbonates of alkaline earth metals, or After coating the surface of each particle of the nickel powder with the alkaline earth metal compound, performing a heat treatment at a temperature lower than the melting temperature of the alkaline earth metal compound in an inert gas or slightly reducing gas atmosphere. Features.
【００３５】前記したように、特開平１１−２３６６３
１号公報等に記載の公知技術においては、出発原料とし
て塩化ニッケル等のニッケルの塩や化合物を用いてい
る。かかる方法によれば、直接還元でニッケル粉を製造
することができるが、均一な還元反応を進め、粒径制御
を行い且つ焼結を防止するためには充分に注意を払う必
要がある。従って、原料混合から反応に至るまでの操作
や制御が非常に煩雑であり、製品の出来ばえにバラツキ
が生じ易い。As described above, JP-A-11-23663
In the known technique described in JP-A No. 1-No. 1 and the like, a salt or compound of nickel such as nickel chloride is used as a starting material. According to this method, nickel powder can be produced by direct reduction. However, sufficient care must be taken to promote a uniform reduction reaction, control the particle size, and prevent sintering. Therefore, the operation and control from the mixing of the raw materials to the reaction are very complicated, and the quality of the product tends to vary.
【００３６】これに対し、本発明の製造方法において
は、出発原料としてニッケル粉を用いるので、焼結の防
止のみを制御すればよく、熱処理の際に共存させるアル
カリ土類金属化合物の溶融温度未満の温度で熱処理する
ことによりニッケル粒子内の平均結晶子径を効率よく大
きくすることが可能である。On the other hand, in the production method of the present invention, since nickel powder is used as a starting material, only prevention of sintering can be controlled, and the temperature is lower than the melting temperature of the alkaline earth metal compound coexisting during the heat treatment. By performing the heat treatment at the above temperature, the average crystallite diameter in the nickel particles can be efficiently increased.
【００３７】本発明の製造方法で出発原料として用いる
ニッケル粉は、液相還元析出法、気相化学反応法、ガス
中蒸発法等の湿式法、乾式法の何れの製造方法で得られ
たものでもよい。湿式法で得られるニッケル粉は粒度分
布に優れているので、湿式法で得られるニッケル粉を出
発原料として用いれば既に粒度分布に優れた状態になっ
ており、また、乾式法で得られるニッケル粉は形状が球
形に近いので、乾式法で得られるニッケル粉を出発原料
として用いれば既に形状が球形に近い状態になってお
り、従って、本発明で目的とする効果の何れに重点を置
くかによって出発原料を適宜選択すればよく、また両者
を配合したり、前処理として風力分級を行って粒度分布
をよりシャープにしたりすることができる。The nickel powder used as a starting material in the production method of the present invention is obtained by any of a wet method such as a liquid phase reduction precipitation method, a gas phase chemical reaction method, a gas evaporation method, and a dry method. May be. Since the nickel powder obtained by the wet method has an excellent particle size distribution, if the nickel powder obtained by the wet method is used as a starting material, the nickel powder already has an excellent particle size distribution, and the nickel powder obtained by the dry method Since the shape is close to a sphere, the shape is already close to a sphere if nickel powder obtained by a dry method is used as a starting material, and therefore, depending on which of the effects targeted in the present invention is emphasized. The starting materials may be appropriately selected, and both may be blended, or the particle size distribution may be sharpened by performing air classification as a pretreatment.
【００３８】本発明の製造方法で用いことのできるアル
カリ土類金属化合物は、アルカリ土類金属の酸化物、水
酸化物、炭酸塩及び炭酸水素塩よりなる群から選ばれた
ものであり、その例としては酸化マグネシウム、酸化カ
ルシウム、水酸化マグネシウム、水酸化カルシウム、炭
酸マグネシウム、炭酸カルシウム、炭酸バリウム、炭酸
水素マグネシウム、炭酸水素カルシウム等を挙げること
ができ、それらは単独で又は２種以上の混合物として使
用することができる。The alkaline earth metal compound which can be used in the production method of the present invention is selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates and hydrogen carbonates. Examples thereof include magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, magnesium carbonate, calcium carbonate, barium carbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, and the like, and these may be used alone or as a mixture of two or more. Can be used as
【００３９】本発明の製造方法においては、先ず、ニッ
ケル粉とアルカリ土類金属化合物の微粉末とを良く混合
するか、又はニッケル粉の個々の粒子の表面にアルカリ
土類金属化合物を被覆させることが重要である。上記の
アルカリ土類金属化合物は融点が高く、且つニッケル粉
との反応性も殆どない上、両者が焼結してしまうことも
ないので、熱処理によりニッケル粒子内の平均結晶子径
を大きくさせる際の焼結防止剤として極めて有効であ
る。従って、アルカリ土類金属化合物の微粉末がニッケ
ル粉中に比較的均一に混合されているか、又はアルカリ
土類金属化合物がニッケル粉の個々の粒子の表面を被覆
していると、この効果が一層良く発揮される。In the production method of the present invention, first, the nickel powder and the fine powder of the alkaline earth metal compound are mixed well, or the surface of each nickel powder particle is coated with the alkaline earth metal compound. is important. The above alkaline earth metal compound has a high melting point, has little reactivity with nickel powder, and does not sinter both. Therefore, when the average crystallite diameter in nickel particles is increased by heat treatment, Is extremely effective as a sintering inhibitor. Therefore, when the fine powder of the alkaline earth metal compound is relatively uniformly mixed in the nickel powder, or when the alkaline earth metal compound covers the surface of each particle of the nickel powder, this effect is further enhanced. It works well.
【００４０】上記の混合方法としては、例えばヘンシェ
ルミキサー等の圧縮作用の少ない混合機を使用する乾式
法を採用することができ、また上記の被覆方法として
は、アルカリ土類金属化合物の水溶液中にニッケル粉を
分散させたニッケル粉含有スラリーを中和処理して共沈
させる方法、スプレードライヤーで造粒する方法により
ニッケル粉表面にアルカリ土類金属化合物を被覆化する
方法等の湿式法を採用することができる。特に、乾式法
ではアルカリ土類金属化合物の微粉末の粒子形状が板状
である場合、湿式法ではアルカリ土類金属化合物が水溶
性、又は酸もしくはアルカリに可溶で溶液として用いる
ことによりアルカリ土類金属化合物がニッケル粉の表面
を薄く均一に被覆している場合、ニッケル粉同士の焼結
が一層有効に防止される。As the above mixing method, for example, a dry method using a mixer having a small compression action such as a Henschel mixer can be adopted. As the above coating method, an aqueous solution of an alkaline earth metal compound is used. A wet method such as a method of neutralizing and coprecipitating a nickel powder-containing slurry in which nickel powder is dispersed, and a method of coating an alkaline earth metal compound on the nickel powder surface by a method of granulating with a spray dryer is employed. be able to. In particular, in the dry method, when the particle shape of the fine particles of the alkaline earth metal compound is plate-like, in the wet method, the alkaline earth metal compound is soluble in an acid or alkali and used as a solution in an alkaline earth metal compound. When the similar metal compound covers the surface of the nickel powder thinly and uniformly, sintering of the nickel powders is more effectively prevented.
【００４１】また、ニッケル粉同士の融着を防止するた
めにはアルカリ土類金属化合物の均一な付着が必要であ
るので、少量のアルカリ土類金属化合物の微粉末を用い
てこの効果を達成するためには、アルカリ土類金属化合
物の微粉末のＳＥＭ観察による平均粒子径がニッケル粉
のＳＥＭ観察による平均粒子径の１／５以下であること
が好ましく、１／８以下であることが一層好ましい。In order to prevent the fusion of nickel powders with each other, it is necessary to uniformly adhere the alkaline earth metal compound. Therefore, this effect can be achieved by using a small amount of fine powder of the alkaline earth metal compound. For this purpose, the average particle diameter of the fine powder of the alkaline earth metal compound by SEM observation is preferably 1/5 or less, more preferably 1/8 or less of the average particle diameter of the nickel powder by SEM observation. .
【００４２】このようにして得られたニッケル粉とアル
カリ土類金属化合物の微粉末との混合物又はアルカリ土
類金属化合物で被覆されたニッケル粉を、引き続き、不
活性ガス又は微還元性ガス雰囲気中で、該アルカリ土類
金属化合物の溶融温度未満の温度で熱処理を実施する。
この熱処理の際に用いることのできる不活性ガス又は微
還元性ガスとしては、窒素、アルゴン、ヘリウムや、一
酸化炭素、水素含有窒素等がある。The thus obtained mixture of the nickel powder and the fine powder of the alkaline earth metal compound or the nickel powder coated with the alkaline earth metal compound is then placed in an inert gas or slightly reducing gas atmosphere. The heat treatment is performed at a temperature lower than the melting temperature of the alkaline earth metal compound.
Examples of the inert gas or slightly reducing gas that can be used in this heat treatment include nitrogen, argon, helium, carbon monoxide, and hydrogen-containing nitrogen.
【００４３】上記のように不活性ガス又は微還元性ガス
雰囲気中で熱処理することによりニッケル粉の酸化を防
止しながら、ニッケル粒子内の平均結晶子径を効率よく
大きくすることができ、また、アルカリ土類金属化合物
の微粉末がニッケル粉の個々の粒子の表面に存在してい
るので、ニッケル粉同士の無用の焼結を抑制することが
できる。As described above, the heat treatment in an atmosphere of an inert gas or a slightly reducing gas can prevent the nickel powder from being oxidized while efficiently increasing the average crystallite size in the nickel particles. Since the fine particles of the alkaline earth metal compound are present on the surfaces of the individual particles of the nickel powder, unnecessary sintering of the nickel powder can be suppressed.
【００４４】なお、熱処理はアルカリ土類金属化合物の
溶融温度未満の温度、好ましくは３００〜８００℃、よ
り好ましくは４００〜６００℃で実施する。また、熱処
理の際の保持時間は好ましくは０．１〜２時間、より好
ましくは０．５〜１時間である。このように熱処理して
得られるニッケル粉においては、ニッケル粒子内の平均
結晶子径が大きくなっている。The heat treatment is performed at a temperature lower than the melting temperature of the alkaline earth metal compound, preferably at 300 to 800 ° C, more preferably at 400 to 600 ° C. The holding time during the heat treatment is preferably 0.1 to 2 hours, more preferably 0.5 to 1 hour. In the nickel powder obtained by the heat treatment as described above, the average crystallite diameter in the nickel particles is large.
【００４５】なお、熱処理はアルカリ土類金属化合物の
溶融温度未満の温度で実施するので、アルカリ土類金属
化合物が溶融してニッケル粒子の微細な窪みや微細な亀
裂中に入り込むことがなく、従ってアルカリ土類金属化
合物は希硫酸等での洗浄、水洗により完全に除去され、
ニッケル粉を汚染する危険性は極めて少ない。Since the heat treatment is performed at a temperature lower than the melting temperature of the alkaline earth metal compound, the alkaline earth metal compound does not melt and enter into the fine dents and fine cracks of the nickel particles. The alkaline earth metal compound is completely removed by washing with dilute sulfuric acid, etc., and washing with water.
The risk of contaminating the nickel powder is extremely low.
【００４６】この熱処理の後、ニッケル粉とアルカリ土
類金属化合物の微粉末との混合物又はアルカリ土類金属
化合物で被覆されたニッケル粉からアルカリ土類金属化
合物を溶解させて除去する。この溶解処理には、アルカ
リ土類金属化合物を溶解することができるものであれば
いかなる液体でもよく、例えば希硫酸等の酸溶液、アン
モニア水等のアルカリ溶液を用いることができる。従っ
て、アルカリ土類金属化合物が水溶性、又は酸もしくは
アルカリに可溶であることが好ましい。この溶解処理の
後充分に水洗し、乾燥して本発明のニッケル粉を得る。After the heat treatment, the alkaline earth metal compound is dissolved and removed from the mixture of the nickel powder and the fine powder of the alkaline earth metal compound or the nickel powder coated with the alkaline earth metal compound. For this dissolution treatment, any liquid may be used as long as it can dissolve the alkaline earth metal compound. For example, an acid solution such as dilute sulfuric acid or an alkaline solution such as aqueous ammonia can be used. Therefore, it is preferable that the alkaline earth metal compound is water-soluble or soluble in acid or alkali. After this dissolving treatment, it is sufficiently washed with water and dried to obtain the nickel powder of the present invention.
【００４７】[0047]
【実施例】以下に実施例及び比較例に基づいて本発明を
具体的に説明する。 比較例１ 硫酸ニッケル・六水和物（品位２２．２質量％）４４．
８ｋｇを純水８０Ｌに溶解して得た水溶液を、水酸化ナ
トリウム濃度２００ｇ／Ｌの水溶液１００Ｌにその液温
を６０℃に維持しながらゆっくりと滴下して、ニッケル
の水酸化物を析出させた。The present invention will be specifically described below based on examples and comparative examples. Comparative Example 1 Nickel sulfate hexahydrate (grade 22.2% by mass)
An aqueous solution obtained by dissolving 8 kg in 80 L of pure water was slowly added dropwise to 100 L of an aqueous solution having a sodium hydroxide concentration of 200 g / L while maintaining the solution temperature at 60 ° C. to precipitate nickel hydroxide. .
【００４８】この懸濁液にその液温を６０℃に維持しな
がらヒドラジン・一水和物３０ｋｇを３０分間にわたっ
て添加してニッケルの水酸化物をニッケルに還元した。
この生成ニッケル粒子含有スラリーを濾過した後、洗浄
液のｐＨが９以下になるまで純水で洗浄し、その後乾燥
してニッケル粉を得た。While maintaining the temperature of the suspension at 60 ° C., 30 kg of hydrazine monohydrate was added over 30 minutes to reduce nickel hydroxide to nickel.
The resulting nickel particle-containing slurry was filtered, washed with pure water until the pH of the washing solution became 9 or less, and then dried to obtain a nickel powder.
【００４９】このニッケル粉について、下記の方法によ
って各特性を求めた。 （１）平均結晶子径 自動Ｘ線回折装置ＲＩＮＴ２２００（株式会社リガク
製）を用いて、Ｘ線回折ピークの半値幅から平均結晶子
径を求めた。The characteristics of the nickel powder were determined by the following methods. (1) Average crystallite diameter Using an automatic X-ray diffractometer RINT2200 (manufactured by Rigaku Corporation), the average crystallite diameter was determined from the half width of the X-ray diffraction peak.
【００５０】（２）ＳＥＭ観察による平均粒子径、粗粒
比率及び微粒比率 １万倍のＳＥＭによって観察し、無作為に選んだ５視野
の合計で１５００個の粒子の粒子径をそれぞれ測定し、
平均粒子径を求めた。また、この平均粒子径の１．２倍
以上の粒子径を持つ粒子個数、及び平均粒子径の０．８
倍以下の粒子径を持つ粒子個数をそれぞれ計測し、全粒
子個数に対する比率を計算した。(2) Average particle diameter, coarse particle ratio, and fine particle ratio by SEM observation Observed by SEM at 10,000 times, and the particle diameters of 1500 particles in a total of five randomly selected visual fields were measured.
The average particle size was determined. Further, the number of particles having a particle diameter of 1.2 times or more of this average particle diameter, and 0.8 of the average particle diameter
The number of particles having a particle diameter of twice or less was measured, and the ratio to the total number of particles was calculated.
【００５１】（３）レーザ回折散乱式粒度分布測定によ
る平均粒子径（Ｄ50値）、粗粒比率、微粒比率及びＣＶ
（％） 試料０．１ｇをＳＮディスパーサント５４６８（サンノ
プコ社製）０．１％水溶液と混合し、超音波ホモジナイ
ザで５分間分散させた後、レーザ回折散乱式粒度分布測
定装置 Micro Trac HRA 9320-X100型（Leeds & Northr
up製）を用いて平均粒子径（Ｄ50値）、Ｄ50値の１．５
倍以上の粒子径を持つ粒子の比率、Ｄ50値の０．５倍以
下の粒子径を持つ粒子の比率、及び個数分布の標準偏差
を測定した。ＣＶはＤ50値及び個数分布の標準偏差を用
いて前記の式（１）に従って計算した。[0051] (3) Average particle diameter (D 50 value) by a laser diffraction scattering particle size distribution measurement, coarse ratio, fine ratio and CV
(%) 0.1 g of a sample was mixed with a 0.1% aqueous solution of SN Dispersant 5468 (manufactured by San Nopco), dispersed with an ultrasonic homogenizer for 5 minutes, and then subjected to laser diffraction scattering type particle size distribution analyzer Micro Trac HRA 9320- X100 (Leeds & Northr
The average particle diameter using a manufactured Stay up-) (D 50 value), 1.5 D 50 value
Proportion of particles with more than twice the particle size, the proportion of particles having a particle size of 0.5 times or less of the D 50 value, and the standard deviation of the number distribution was measured. CV was calculated according to equation (1) of using said standard deviation of the D 50 value and the number distribution.
【００５２】（４）化学分析値 試料を溶解し、Ｎａ及びＳはＩＣＰによって測定し、Ｃ
ｌは比濁法によって測定した。上記（１）〜（４）の測
定、計算結果は第１表に示す通りであった。(4) Chemical analysis value The sample was dissolved, and Na and S were measured by ICP.
l was measured by turbidimetry. The measurement and calculation results of the above (1) to (4) are as shown in Table 1.
【００５３】実施例１ 比較例１で得たニッケル粉１００ｇと板状炭酸水素マグ
ネシウム１００ｇとをヘンシェルミキサーで混合した
後、窒素通気量１Ｌ／分の窒素雰囲気中で、６００℃で
１時間加熱した。その後、希硫酸で洗浄してマグネシウ
ム成分を除去し、水洗し、濾過し、乾燥して目的とする
ニッケル粉を得た。このニッケル粉について、比較例１
の場合と同様にして各特性を求めた。その結果は第１表
に示す通りであった。Example 1 100 g of the nickel powder obtained in Comparative Example 1 and 100 g of plate-shaped magnesium hydrogen carbonate were mixed with a Henschel mixer, and heated at 600 ° C. for 1 hour in a nitrogen atmosphere with a nitrogen flow rate of 1 L / min. . Thereafter, the magnesium component was removed by washing with dilute sulfuric acid, washed with water, filtered, and dried to obtain a desired nickel powder. About this nickel powder, Comparative Example 1
Each characteristic was determined in the same manner as in the above case. The results were as shown in Table 1.
【００５４】実施例２ 比較例１で得たニッケル粉１００ｇと酸化マグネシウム
（一次粒子径５０ｎｍ）３０ｇとをヘンシェルミキサー
で混合した後、アルゴン通気量１Ｌ／分のアルゴン雰囲
気中で、８００℃で１時間加熱した。その後、希硫酸で
洗浄してマグネシウム成分を除去し、水洗し、濾過し、
乾燥して目的とするニッケル粉を得た。このニッケル粉
について、比較例１の場合と同様にして各特性を求め
た。その結果は第１表に示す通りであった。Example 2 100 g of the nickel powder obtained in Comparative Example 1 and 30 g of magnesium oxide (primary particle diameter: 50 nm) were mixed by a Henschel mixer, and then mixed at 800 ° C. in an argon atmosphere at an argon flow rate of 1 L / min. Heated for hours. After that, it is washed with dilute sulfuric acid to remove the magnesium component, washed with water, filtered,
After drying, the desired nickel powder was obtained. The characteristics of the nickel powder were determined in the same manner as in Comparative Example 1. The results were as shown in Table 1.
【００５５】実施例３ 比較例１で得たニッケル粉１００ｇを水１Ｌ中に良く分
散させた後、この分散スラリーに硝酸カルシウム・四水
和物２３６ｇを添加し、攪拌して均一に溶解させた。更
に、この分散スラリーに水酸化ナトリウム水溶液を添加
してｐＨを８に調整し、１時間攪拌した後、濾過し、乾
燥した。このようにして得た水酸化カルシウム被覆ニッ
ケル粉を窒素通気量１Ｌ／分の窒素雰囲気中で、５００
℃で１時間加熱した。その後、希硫酸で洗浄してカルシ
ウム成分を除去し、水洗し、濾過し、乾燥して目的とす
るニッケル粉を得た。このニッケル粉について、比較例
１の場合と同様にして各特性を求めた。その結果は第１
表に示す通りであった。Example 3 After 100 g of the nickel powder obtained in Comparative Example 1 was well dispersed in 1 L of water, 236 g of calcium nitrate tetrahydrate was added to this dispersion slurry, and the mixture was stirred and uniformly dissolved. . Further, an aqueous sodium hydroxide solution was added to the dispersion slurry to adjust the pH to 8, and the mixture was stirred for 1 hour, filtered, and dried. The calcium hydroxide-coated nickel powder thus obtained is placed in a nitrogen atmosphere at a nitrogen flow rate of 1 L / min in a nitrogen atmosphere.
Heated at 0 ° C. for 1 hour. Then, the calcium component was removed by washing with dilute sulfuric acid, washed with water, filtered, and dried to obtain the desired nickel powder. The characteristics of the nickel powder were determined in the same manner as in Comparative Example 1. The result is the first
As shown in the table.
【００５６】比較例２ 板状炭酸水素マグネシウムを使用しなかった以外は実施
例１の場合と同様に処理してニッケル粉を得た。このニ
ッケル粉について、比較例１の場合と同様にして各特性
を求めた。その結果は第１表に示す通りであった。Comparative Example 2 A nickel powder was obtained by treating in the same manner as in Example 1 except that the plate-like magnesium bicarbonate was not used. The characteristics of the nickel powder were determined in the same manner as in Comparative Example 1. The results were as shown in Table 1.
【００５７】比較例３ 特開平１１−２３６６３１号公報に記載の実施例２の方
法に準じて、無水塩化ニッケル粉２２１ｇ、還元剤とし
てマグネシウム金属２７ｇ（１．１当量）及び無水塩化
カルシウム１５１ｇをグローボックス中で充分に混合し
た後、純ニッケル製の反応容器に入れ、蓋をし、その後
ステンレス製の反応容器に入れてアルゴンガスで置換し
た後、３０分間で１０００℃まで昇温させ、１０００℃
に３０分間保持した後８００℃まで降温させ、次いで電
気炉から反応容器を取り出して室温まで空冷した。Comparative Example 3 According to the method of Example 2 described in JP-A-11-236631, 221 g of anhydrous nickel chloride powder, 27 g (1.1 equivalents) of magnesium metal and 151 g of anhydrous calcium chloride as a reducing agent were glowed. After thoroughly mixing in a box, put in a reaction vessel made of pure nickel, cover, and then put in a reaction vessel made of stainless steel and replace with argon gas.
After the temperature was lowered to 800 ° C., the reaction vessel was taken out of the electric furnace and air-cooled to room temperature.
【００５８】その後、その還元生成物をクラッシャーで
数ミリ程度の粒状に粉砕後、レパルプ、沈降を繰り返す
ことにより水洗し、塩化カルシウムを除去した後、固液
分離することにより微細ニッケル粉を回収した。固液分
離で回収したスラリー又はケーキ状の湿潤な微細ニッケ
ル粉を１５０℃の気流中で解砕しながら乾燥した。この
ニッケル粉について、比較例１の場合と同様にして各特
性を求めた。その結果は第１表に示す通りであった。Thereafter, the reduced product was pulverized by a crusher into granules of about several millimeters, washed with water by repeating repulping and sedimentation, removing calcium chloride, and then solid-liquid separated to recover fine nickel powder. . The slurry or cake-like wet fine nickel powder recovered by solid-liquid separation was dried while being crushed in an air stream at 150 ° C. The characteristics of the nickel powder were determined in the same manner as in Comparative Example 1. The results were as shown in Table 1.
【００５９】[0059]
【表１】 [Table 1]
【００６０】第１表のデータから明らかなように、実施
例１〜３で得られたニッケル粉は、出発原料のニッケル
粉と比較して平均結晶子径が大きくなっており、また平
均粒子径に対する粗粒、微粒の比率少なく、粒度分布が
シャープである。また、ナトリウム、硫黄、塩素等の不
純物の含有量も充分に低い。As is clear from the data in Table 1, the nickel powders obtained in Examples 1 to 3 had a larger average crystallite diameter and a larger average particle diameter than the nickel powder as the starting material. And the particle size distribution is sharp. Further, the content of impurities such as sodium, sulfur, and chlorine is sufficiently low.
【００６１】これに対して、比較例１で得られたニッケ
ル粉は熱処理を加えていないため、粒度分布はシャープ
であるものの、平均結晶子径が小さいものであった。比
較例２で得られたニッケル粉は、平均結晶子径がかなり
大きいものの、アルカリ土類金属化合物の微粉末を使用
していないため、出発原料のニッケル粉の焼結が進み、
導電ペースト用途には全く適さないニッケル粉になって
いた。また、比較例３で得られたニッケル粉は、平均結
晶子径がかなり大きいものの、出発原料としてニッケル
塩を用いたことに起因して還元生成されたニッケルの粒
径を制御しきれずにバラツキが大きかった。On the other hand, since the nickel powder obtained in Comparative Example 1 was not heat-treated, the particle size distribution was sharp but the average crystallite diameter was small. Although the nickel powder obtained in Comparative Example 2 has a considerably large average crystallite size, the sintering of the nickel powder as a starting material proceeds because fine powder of an alkaline earth metal compound is not used,
The nickel powder was completely unsuitable for conductive paste applications. In addition, the nickel powder obtained in Comparative Example 3 has a considerably large average crystallite diameter, but has a variation in the particle size of the nickel produced and reduced due to the use of the nickel salt as a starting material, and thus cannot be controlled. It was big.
【００６２】[0062]
【発明の効果】本発明のニッケル粉は、粒度分布がシャ
ープであることに起因して積層セラミックコンデンサの
薄くて突起がない内部電極を形成することができ且つニ
ッケル粒子内の平均結晶子径が大きいことに起因して熱
収縮が抑制された内部電極を形成することができ、導電
ペースト用途に特に適している。また、凝集が少なく単
分散状態に近いことに起因して導電ペーストの製造の際
の有機ビヒクル中での分散性が優れており且つニッケル
粒子内の平均結晶子径が大きいことに起因して熱収縮が
抑制された内部電極を形成することができ、導電ペース
ト用途に特に適している。また、本発明の製造方法によ
れば、出発原料のニッケル粉の長所を損なうことなし
で、平均結晶子径の大きいニッケル粉を製造することが
できる。The nickel powder of the present invention can form a thin, projection-free internal electrode of a multilayer ceramic capacitor due to its sharp particle size distribution, and has an average crystallite diameter in nickel particles. An internal electrode in which thermal shrinkage is suppressed due to its large size can be formed, which is particularly suitable for a conductive paste application. In addition, the dispersibility in the organic vehicle during the production of the conductive paste is excellent due to little aggregation and close to the monodispersed state, and the heat due to the large average crystallite size in the nickel particles is large. An internal electrode with suppressed shrinkage can be formed, which is particularly suitable for conductive paste applications. Further, according to the production method of the present invention, nickel powder having a large average crystallite diameter can be produced without impairing the advantages of nickel powder as a starting material.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 林 尚男 山口県下関市彦島西山町１−１−１ 三井 金属鉱業株式会社ケミカル事業部内 (72)発明者 島村 宏之 東京都品川区大崎１−11−１ 三井金属鉱 業株式会社内 Ｆターム(参考） 4K018 BA04 BB04 BB06 BC20 BC28 BD04 5G301 DA10 DD01 DE03 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nao Hayashi 1-1-1 Hikoshima Nishiyamacho, Shimonoseki City, Yamaguchi Prefecture Mitsui Metal Mining Co., Ltd. Chemical Division (72) Inventor Hiroyuki Shimamura 1-11-1 Osaki, Shinagawa-ku, Tokyo 1 Mitsui Mining & Mining Co., Ltd. F term (reference) 4K018 BA04 BB04 BB06 BC20 BC28 BD04 5G301 DA10 DD01 DE03
Claims (9)
上の粒子径を持つ粒子個数が全粒子個数の１０％以下で
あり、該平均粒子径の０．８倍以下の粒子径を持つ粒子
個数が全粒子個数の１０％以下であり、且つニッケル粒
子内の平均結晶子径が４００Å以上であることを特徴と
するニッケル粉。1. The number of particles having a particle diameter of 1.2 times or more the average particle diameter by SEM observation is 10% or less of the total number of particles, and has a particle diameter of 0.8 times or less of the average particle diameter. A nickel powder, wherein the number of particles is 10% or less of the total number of particles, and the average crystallite size in the nickel particles is 400 ° or more.
粒子径（Ｄ50値）の１．５倍以上の粒子径を持つ粒子個
数が全粒子個数の２０％以下であり、該平均粒子径（Ｄ
50値）の０．５倍以下の粒子径を持つ粒子個数が全粒子
個数の５％以下であり、且つニッケル粒子内の平均結晶
子径が４００Å以上であることを特徴とするニッケル
粉。Wherein the number of particles having a particle size of 1.5 times or more the average particle diameter measured by a laser diffraction scattering particle size distribution measurement (D 50 value) is not more than 20% of the total number of particles, the average particle size ( D
Nickel powder characterized in that the number of particles having a particle diameter of 0.5 times or less of ( 50 value) is 5% or less of the total number of particles, and the average crystallite diameter in the nickel particles is 400 ° or more.
（ＣＶ）が４０％未満であることを特徴とする請求項１
又は２記載のニッケル粉。 【数１】 3. The coefficient of variation (CV) determined by the following equation (1) is less than 40%.
Or the nickel powder according to 2. (Equation 1)
０ｐｐｍ以下であり、塩素量が１００ｐｐｍ以下であ
り、硫黄量が１００００ｐｐｍ以下であることを特徴と
する請求項１、２又は３記載のニッケル粉。4. The total amount of the alkali metal in the nickel powder is 50.
The nickel powder according to claim 1, wherein the nickel powder is 0 ppm or less, the chlorine content is 100 ppm or less, and the sulfur content is 10000 ppm or less.
水酸化物、炭酸塩及び炭酸水素塩よりなる群から選ばれ
たアルカリ土類金属化合物の微粉末とを混合した後、ま
たはニッケル粉の各粒子表面に該アルカリ土類金属化合
物を被覆させた後、不活性ガス又は微還元性ガス雰囲気
中で、該アルカリ土類金属化合物の溶融温度未満の温度
で熱処理を実施することを特徴とするニッケル粉の製造
方法。5. An oxide of nickel powder and an alkaline earth metal,
After mixing with a fine powder of an alkaline earth metal compound selected from the group consisting of hydroxide, carbonate and bicarbonate, or after coating the surface of each particle of nickel powder with the alkaline earth metal compound A heat treatment in an atmosphere of an inert gas or a slightly reducing gas at a temperature lower than a melting temperature of the alkaline earth metal compound.
状が板状である請求項５記載のニッケル粉の製造方法。6. The method according to claim 5, wherein the fine particles of the alkaline earth metal compound have a plate-like particle shape.
観察による平均粒子径が、ニッケル粉のＳＥＭ観察によ
る平均粒子径の１／５以下である請求項５又は６記載の
ニッケル粉の製造方法。7. SEM of fine powder of alkaline earth metal compound
The method for producing nickel powder according to claim 5 or 6, wherein the average particle diameter by observation is not more than 1/5 of the average particle diameter by SEM observation of the nickel powder.
もしくはアルカリに可溶である請求項５、６又は７記載
のニッケル粉の製造方法。8. The method for producing nickel powder according to claim 5, wherein the alkaline earth metal compound is water-soluble or soluble in an acid or an alkali.
る請求項５、６、７又は８記載のニッケル粉の製造方
法。9. The method for producing nickel powder according to claim 5, wherein the heat treatment is performed at a temperature of 300 to 800 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000341649A JP3945740B2 (en) | 2000-11-09 | 2000-11-09 | Nickel powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000341649A JP3945740B2 (en) | 2000-11-09 | 2000-11-09 | Nickel powder |
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|---|---|---|---|
| JP2007056264A Division JP2007197836A (en) | 2007-03-06 | 2007-03-06 | Nickel powder |
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| Publication Number | Publication Date |
|---|---|
| JP2002146401A true JP2002146401A (en) | 2002-05-22 |
| JP2002146401A5 JP2002146401A5 (en) | 2006-06-29 |
| JP3945740B2 JP3945740B2 (en) | 2007-07-18 |
Family
ID=18816359
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| Application Number | Title | Priority Date | Filing Date |
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| JP2000341649A Expired - Lifetime JP3945740B2 (en) | 2000-11-09 | 2000-11-09 | Nickel powder |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004084069A (en) * | 2002-06-28 | 2004-03-18 | Mitsui Mining & Smelting Co Ltd | Inorganic oxide coated metal powder and its manufacturing method |
| JP2005154861A (en) * | 2003-11-27 | 2005-06-16 | Mitsui Mining & Smelting Co Ltd | Double layer-coated copper powder, method of producing the double layer-coated copper powder, and electrically conductive paste using the double layer-coated copper powder |
| JP2009052146A (en) * | 2008-11-26 | 2009-03-12 | Dowa Holdings Co Ltd | Copper powder and its manufacturing method |
| WO2011037150A1 (en) * | 2009-09-24 | 2011-03-31 | 住友金属鉱山株式会社 | Nickel powder and production method thereof |
| WO2014073082A1 (en) * | 2012-11-08 | 2014-05-15 | エム・テクニック株式会社 | Fine metal particles provided with projections |
| JP2015086469A (en) * | 2013-08-07 | 2015-05-07 | ニホンハンダ株式会社 | Method of producing metal fine particle continuously, conductive curable composition and electronic apparatus |
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2000
- 2000-11-09 JP JP2000341649A patent/JP3945740B2/en not_active Expired - Lifetime
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004084069A (en) * | 2002-06-28 | 2004-03-18 | Mitsui Mining & Smelting Co Ltd | Inorganic oxide coated metal powder and its manufacturing method |
| JP2005154861A (en) * | 2003-11-27 | 2005-06-16 | Mitsui Mining & Smelting Co Ltd | Double layer-coated copper powder, method of producing the double layer-coated copper powder, and electrically conductive paste using the double layer-coated copper powder |
| JP2009052146A (en) * | 2008-11-26 | 2009-03-12 | Dowa Holdings Co Ltd | Copper powder and its manufacturing method |
| WO2011037150A1 (en) * | 2009-09-24 | 2011-03-31 | 住友金属鉱山株式会社 | Nickel powder and production method thereof |
| JPWO2011037150A1 (en) * | 2009-09-24 | 2013-02-21 | 住友金属鉱山株式会社 | Nickel fine powder and method for producing the same |
| JP5626217B2 (en) * | 2009-09-24 | 2014-11-19 | 住友金属鉱山株式会社 | Nickel fine powder and method for producing the same |
| WO2014073082A1 (en) * | 2012-11-08 | 2014-05-15 | エム・テクニック株式会社 | Fine metal particles provided with projections |
| JPWO2014073082A1 (en) * | 2012-11-08 | 2016-09-08 | エム・テクニック株式会社 | Metal fine particles with protrusions |
| US9928932B2 (en) | 2012-11-08 | 2018-03-27 | M. Technique Co., Ltd. | Metal microparticles provided with projections |
| JP2015086469A (en) * | 2013-08-07 | 2015-05-07 | ニホンハンダ株式会社 | Method of producing metal fine particle continuously, conductive curable composition and electronic apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3945740B2 (en) | 2007-07-18 |
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