JP4147657B2 - Nickel powder for internal electrode paste of multilayer ceramic capacitor - Google Patents
Nickel powder for internal electrode paste of multilayer ceramic capacitor Download PDFInfo
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Description
【0001】
【発明の属する技術分野】
本発明は積層セラミックコンデンサーの内部電極材料のペースト用として用いられるニッケル粉に関するものである。
【0002】
【従来の技術】
現在、電子機器の小型化に伴い電子部品の小型化が急速に進められたおり、このような状況において積層セラミックコンデンサー(MLCC)が小型・高容量のコンデンサーとして大量に使用されている。このような積層セラミックコンデンサーの内部電極材料には従来、パラジウム、白金などの貴金属が主として使用されていた。
しかしコンデンサーの高容量化のために積層数が増加し、前述のような貴金属粉末を使用したのではコストが高くなるという問題があり、最近ではコスト低減のために内部電極材料としてニッケル粉が多用されている。
【0003】
内部電極材料として使用されるニッケル粉はバインダー中に分散させてペーストとし、このペーストを基板上に印刷塗布し、多層積み重ねて圧着し、還元雰囲気中で約1300℃で焼成して電極を形成させ、コンデンサーとしての特性を発揮させる。
通常この内部電極の厚みは、焼成後で2〜3μmであるが近年、コンデンサーの高容量化・小型化の進展に伴いより薄い電極を形成する必要が生じてきた。
しかしながらニッケル塗膜中のニッケル粉の充填密度は粉末冶金における成形体の充填密度に比べてはるかに低く、しかも基板となるセラミックスグリーンシー卜の焼結に伴う収縮量がニッケル電極膜の収縮に比べて小さいために、焼結の進行に伴ってニッケル膜が島状に途切れるという問題が発生した。このようにニッケル電極が途切れた場合は、コンデンサーとして機能しなくなるため、コンデンサーの小型・大容量化のためには、焼結時の収縮をできるだけ小さく抑えながら、緻密で薄い電極を形成することが不可欠である。
【0004】
また、電極を薄層化したときの他の問題点は、絶縁破壊による信頼性の低下である。これはニッケル電極の突起部分の層間距離が短くなることによって発生する場合が多く、薄層化が進むほど、誘電体層の厚みは薄くなるためニッケル電極表面の突起の影響を受け易くなるからである。
【0005】
【発明が解決しようとする課題】
本発明は積層セラミックコンデンサーの製造工程において、ニッケル電極厚みを薄くしたときに生じる電極途切れによるコンデンサーとしての機能停止や、ニッケル電極表面に突起が生成することによる寿命・信頼性の低下を防止するために有効な積層セラミックコンデンサーの内部電極ペースト用ニッケル粉を提供することにある。
【0006】
【課題を解決するための手段】
上記課題を解決するため本発明は、TiまたはSiのうち少なくとも1種を、少なくともその表面に0.02〜1質量%含有したニッケル粉であって、
1)前記ニッケル粉は、空気中400℃で2時間保持したときの酸化重量増加率が15%未満であり、
2)前記ニッケル粉は、XRD法により求めた結晶子サイズが300オングストローム以上であり、
3)前記ニッケル粉の粉末の真比重が8.5以上であり、且つ、
4)前記ニッケル粉のSEM写真観察において、その平均粒径の2倍以上の粒径を有する粒子が、全体の100分の1以下、
であることを特徴とするものである。
【0007】
【発明の実施の形態】
つぎに本発明を具体的に説明する。
本発明では以下の構成を有することを特徴とする。
(1)空気中で2時間保持したときの酸化重量増加率が15%未満であること;
ニッケル粉はバインダーとなる樹脂と混合してペースト化され、誘電体シート上に塗工され、乾燥される。この後該シートは積層され、焼成工程に入るが、焼成の初期段階においてバインダー成分を除去する工程が組み込まれる。脱バインダーの方式は殆どの場合、酸化雰囲気で400℃以下で加熱し、樹脂を分解・揮発させる方式が取られるが、この際ニッケル粉までが酸化されてしまう。
酸化されたニッケル粉表面は続く還元雰囲気下での焼結工程で再度還元されるが、その際に0.1μm以下の極めて微細なニッケル粉を生じる。このような微細なニッケル粉は焼結の開始温度を低下させる働きがあり、その結果焼結時に電極と誘電体層との収縮の間に大きな時間差が発生して、これに起因するクラックなど構造欠陥が発生し易くなる。
【0008】
本発明者らはニッケル粉の耐酸化性の指標として空気中400℃で2時間保持したときの酸化重量増加率を用いて、この値が15%以上になる酸化雰囲気での脱バインダー工程ではクラックが発生し易くなり、一方15%未満、好ましくは13%を下回る酸化雰囲気ではクラックの発生が極めて少なくなること、および前記酸化重量増加率はニッケル粉のX線回折(XRD)法により求めた結晶子サイズと密接に関連し、該サイズを300オングストローム以上とすると酸化重量増加率が15%未満となることを見出した。
【0009】
従来より、耐酸化性の高いニッケル粉としては気相法により得られた粒子径の大きいものが好適であることが知られており、該気相法により得られたニッケル粉ではXRD法により求めた結晶子サイズが1000オングストローム以上である。そしてこの方法で得られた大きな結晶子サイズを有するニッケル粉は、結晶粒界が少なく、酸素の粒界拡散による内部酸化の進行が遅いために耐酸化性が高いといわれていたが、粒子の表面積が広いため空気中400℃で2時間保持したときの酸化重量増加率は15%以上となり、脱バインダー時の酸素分圧によってはクラックが発生し易いという問題は解消されずにそのまま残っている。
【0010】
一方通常の水酸化ニッケルの湿式還元法で得られるニッケル粉の結晶子サイズは平均粒径により変動するものの、XRD法で求めたサイズは100〜500オングストロームと小さく本来本発明で使用するニッケル粉として好適でないと考えられていた。しかし湿式還元法で得られるニッケル粉の結晶子サイズが300オングストロームに満たない場合は、加熱保持による結晶成長や、好ましくは特願平10−268160号記載の方法を実施することにより、結晶子サイズを300オングストローム以上とすることができるので、これにより耐酸化性向上効果をより確実に実現できることが判明した。
なお、結晶成長はTiおよび/またはSiの添加処理後に、非酸化性雰囲気中400〜600℃で加熱保持することによっても実現できる。
【0011】
(2)Ti、Siのうちいずれか一方、または両方を0.02質量%〜1質量%含有すること;
結晶子サイズは300オングストローム以上であれば、大きいほど好ましいが、大きい結晶子サイズのニッケル粉でも粒子表面の耐酸化性を高めなければ上記問題は克服することができない。本発明者らはニッケル粒子表面にTiあるいはSiのうちいずれか一方、または両方を0.02質量%〜1質量%を存在させる
ことによりニッケル粉粒子表面の耐酸化性が向上することを見出した。
Tiおよび/またはSiを添加することによる耐酸化性の向上効果は、粒子表面付近にこれら元素が存在することでTi、Siを含む酸化ニッケル層が粒子表面に形成され、これにより内部まで酸化が進行することを抑制できるものと推定される。
これら元素の添加方法は、ニッケル粉を水溶液に懸濁させ、Siを含む有機化合物もしくはTiを含む有機化合物を加え撹拌混合することによって、ニッケル粉の表面に前記元素を吸着させた後、濾過乾燥することにより得られる。
【0012】
TiまたはSiの添加量が、それぞれ単独もしくは合計で0.02質量%未満では、前記効果が得られず、一方1質量%を超えて添加するとニッケル焼結を阻害する可能性があるので好ましくない。特にTiの量が多い場合は、相手となるチタン酸バリウムの誘電体の組成を変えてしまう恐れがあり、設計通りの誘電率が得られないこととなる。
【0013】
(3)粉末の真比重が8.2以上であること;
ニッケル粉の真比重が8.2を上回った時点で焼結時の収縮が小さくなり1μmの電極でも途切れが発生し難いことを見出した。そしてニッケル粉の真密度は高いほど有利である。
(4)SEM写真観察において平均粒径の2倍以上の粒径を有する粒子の割合が100分の1以下であること;
【0014】
真密度の高いニッケル粉としては気相法による結晶子サイズの大きいニッケル粉が知られている。しかしこのニッケル粉はそのプロセス上の特徴により平均粒子径の2倍以上の大きさを持つ粒子の混入を避けることができない。
そして電極を薄層化した場合には、これら粗大粒子が電極の突起の原因となり、この電極の突起部分はそのまま層間距離が短くなるため絶縁破壊を起こし易く、コンデンサーの寿命、信頼性を低下させるため好ましくない。また薄層化が進むほど、誘電体厚みは薄くなるため電極の突起に対して敏感となる。問題となる粗大粒子の大きさは、一般的には設計電極厚みを超えなければよいとされているが、実際にはそれ以下の大きさであっても平均粒径の粒子の大きさとの差が大きい粒子が多く存在した場合には突起の原因になる場合が多い。本発明者らは検討の結果、ニッケル粉に含まれる粒子のうち平均粒径の2倍以上の粒径を有する粒子が多く存在するものは電極突起の原因となり易いこと、換言すると平均粒径の2倍以上の粒子粒径を有する粒子を全体の100分の1以下とすると電極における絶縁破壊を防止できることを見出した。
【0015】
実用的には、電極の厚みは焼成後で2〜3μmであるので、SEM写真観察による平均粒径が1μm以下であり、その2倍である2μm以上の粒径を有する粒子量を極力抑えること、具体的には100分の1以下とすることでこの問題は解決できることが分かった。
【0016】
【実施例】
[実施例1]
結晶子サイズが800オングストロームであるニッケル粉(住友金属鉱山(株)製)を水溶液中に懸濁させてチタネート系カップリング剤(味の素(株)製 KR−ET:商品名)を添加し、pH7、室温で撹拌保持し、Tiを吸着させてTiの含有量が500ppmであるニッケル粉を得た。
このニッケル粉は、真比重が8.5、SEM写真対角線法による平均粒径0.56μmであって1μm以上の粒子の存在が見られず、空気中400℃で2時間保持したときの酸化重量増加率が11%であった。
このニッケル粉を用いて熱機械分析(TMA)による1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に示す。
【0017】
[実施例2]
結晶子サイズが800オングストロームであるニッケル粉(住友金属鉱山(株)製)を水溶液中に懸濁させてシランカップリング剤の1種であるγ−グリシドキシプロピルトリメトキシシランのエタノール溶液を加え、pH10、70℃で撹拌保持し、Siを吸着させてSiの含有量が500ppmであるニッケル粉を得た。
このニッケル粉は、真比重が8.8、SEM写真対角線法による平均粒径0.56μmであって1μm以上の粒子の存在が見られず、空気中400℃で2時間保持したときの酸化重量増加率が8%であった。
このニッケル粉を用いてTMAによる1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に併せて示す。
【0018】
[実施例3]
結晶子サイズが150オングストロームであるニッケル粉を使用した以外は実施例1と同様にTiの含有量が500ppmであるニッケル粉を得た。このニッケル粉を水素2%、窒素98%の気流中、600℃で1時間加熱保持し、結晶子サイズを900オングストロームとした。このニッケル粉は、真比重が8.5、SEM写真対角線法による平均粒径0.58μmであって1μm以上の粒子の存在が見られず、空気中400℃で2時間保持したときの酸化重量増加率が13%であった。
このニッケル粉のTMAによる1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に併せて示す。
【0019】
[比較例1]
結晶子サイズが700オングストローム、真比重が7.9、SEM写真対角線法による平均粒径0.56μmであって1μm以上の粒子の存在が見られず、空気中400℃で2時間保持したときの酸化重量増加率が20%でTiおよびSiの含有量が10ppm未満であるニッケル粉(住友金属鉱山(株)製)を用いてTMAによる1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に併せて示す。
【0020】
[比較例2]
結晶子サイズが800オングストローム、真比重が8.5、SEM写真対角線法による一次粒子の平均粒径0.57μmであって1μm以上の二次凝集体を多く含み、空気中400℃で2時間保持したときの酸化重量増加率が11%で、Tiの含有量が500ppmであるニッケル粉(住友金属鉱山(株)製)を用いてTMAによる1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に併せて示す。
【0021】
[比較例3]
結晶子サイズが700オングストローム、真比重が8.5、SEM写真対角線法による平均粒径0.56μmであって1μm以上の粒子の存在が見られず、空気中400℃で2時間保持したときの酸化重量増加率が20%で、TiおよびSi含有量が10ppm未満であるニッケル粉(住友金属鉱山(株)製)を用いてTMAによる1000℃における収縮挙動の調査および塗膜焼成後の電極状態を観察した。その結果を下記する表1に併せて示す。
【0022】
【表1】
【0023】
表1から分かる通り、本発明の実施例では1000℃における収縮率は、いずれも15%以下でクラックの発生もなく、ニッケル電極の途切れもなかった。一方比較例1、2では収縮率が20%、25%と高くクラックが生じ、かつニッケル電極の途切れが発生し、また比較例3は収縮率は15%であったが、ニッケル電極の途切れが発生してしまった。
【0024】
【発明の効果】
以上述べた通り本発明によれば、積層セラミックコンデンサーの製造工程において、電極途切れによるコンデンサーとしての機能停止や、絶縁破壊による寿命・信頼性の低下を防止することができ、極めて有効な積層セラミックコンデンサーの内部電極ペースト用ニッケル粉を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to nickel powder used as a paste for internal electrode material of a multilayer ceramic capacitor.
[0002]
[Prior art]
At present, electronic components have been rapidly miniaturized as electronic devices have been miniaturized. In such a situation, multilayer ceramic capacitors (MLCCs) are used in large quantities as small-sized and high-capacitance capacitors. Conventionally, noble metals such as palladium and platinum have been mainly used as internal electrode materials for such multilayer ceramic capacitors.
However, the number of laminated layers has increased due to the increase in the capacity of capacitors, and there is a problem that the use of the above-mentioned precious metal powder increases the cost. Recently, nickel powder is frequently used as an internal electrode material to reduce the cost. Has been.
[0003]
Nickel powder used as an internal electrode material is dispersed in a binder to form a paste. This paste is printed and applied onto a substrate, stacked and pressure-bonded, and fired at about 1300 ° C. in a reducing atmosphere to form an electrode. , To exhibit the characteristics as a capacitor.
Normally, the thickness of the internal electrode is 2 to 3 μm after firing, but in recent years, it has become necessary to form a thinner electrode with the progress of higher capacity and smaller size of the capacitor.
However, the packing density of the nickel powder in the nickel coating is much lower than the packing density of the compact in powder metallurgy, and the amount of shrinkage associated with the sintering of the ceramic green sheet used as the substrate is smaller than that of the nickel electrode film. Therefore, there was a problem that the nickel film was cut into islands as the sintering progressed. If the nickel electrode breaks in this way, it will not function as a capacitor. Therefore, in order to reduce the size and increase the capacity of the capacitor, it is possible to form a dense and thin electrode while minimizing the shrinkage during sintering. It is essential.
[0004]
Another problem when the electrode is thinned is a decrease in reliability due to dielectric breakdown. This is often caused by a decrease in the interlayer distance between the protrusions of the nickel electrode, and the thinner the layer, the thinner the dielectric layer, and the more easily affected by the protrusions on the nickel electrode surface. is there.
[0005]
[Problems to be solved by the invention]
In the manufacturing process of the multilayer ceramic capacitor, the present invention prevents a function stop as a capacitor due to electrode interruption that occurs when the nickel electrode thickness is reduced, and a decrease in life and reliability due to the formation of protrusions on the surface of the nickel electrode. An object of the present invention is to provide nickel powder for internal electrode paste of a multilayer ceramic capacitor which is effective for the above.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a nickel powder containing at least one of Ti and Si at least 0.02 to 1% by mass on the surface thereof,
1) The nickel powder has an oxidation weight increase rate of less than 15% when held in air at 400 ° C. for 2 hours,
2) The nickel powder has a crystallite size determined by an XRD method of 300 angstroms or more,
3) The true specific gravity of the nickel powder powder is 8.5 or more, and
4) In the SEM photograph observation of the nickel powder, particles having a particle size of twice or more of the average particle size are 1/100 or less of the total,
It is characterized by being.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be specifically described.
The present invention has the following configuration.
(1) Oxidized weight increase rate when kept in air for 2 hours is less than 15%;
Nickel powder is mixed with a resin serving as a binder to form a paste, which is coated on a dielectric sheet and dried. After this, the sheets are laminated and enter the firing step, but a step of removing the binder component is incorporated in the initial stage of firing. In most cases, the debinding method is such that the resin is decomposed and volatilized by heating at 400 ° C. or lower in an oxidizing atmosphere, but even the nickel powder is oxidized at this time.
The oxidized nickel powder surface is reduced again in the subsequent sintering step under a reducing atmosphere, and at that time, extremely fine nickel powder of 0.1 μm or less is produced. Such fine nickel powder has the function of lowering the starting temperature of the sintering, and as a result, a large time difference occurs between the contraction of the electrode and the dielectric layer during sintering, resulting in cracks and other structures Defects are likely to occur.
[0008]
The inventors used the rate of increase in oxidized weight when kept at 400 ° C. in air for 2 hours as an index of oxidation resistance of nickel powder. In the binder removal step in an oxidizing atmosphere in which this value is 15% or more, cracks occur. On the other hand, the occurrence of cracks is extremely reduced in an oxidizing atmosphere of less than 15%, preferably less than 13%, and the rate of increase in oxidized weight is determined by the X-ray diffraction (XRD) method of nickel powder. It was closely related to the child size, and it was found that the oxidation weight increase rate was less than 15% when the size was 300 angstroms or more.
[0009]
Conventionally, it has been known that a nickel powder having a large particle diameter obtained by a vapor phase method is suitable as a nickel powder having high oxidation resistance, and the nickel powder obtained by the vapor phase method is obtained by an XRD method. The crystallite size is 1000 angstroms or more. The nickel powder having a large crystallite size obtained by this method was said to have high oxidation resistance because it has few crystal grain boundaries and the progress of internal oxidation due to oxygen grain boundary diffusion is slow. Since the surface area is large, the rate of increase in oxidized weight when kept in air at 400 ° C. for 2 hours is 15% or more, and the problem that cracks are likely to occur depending on the oxygen partial pressure at the time of debinding remains as it is. .
[0010]
On the other hand, although the crystallite size of the nickel powder obtained by the usual wet reduction method of nickel hydroxide varies depending on the average particle diameter, the size obtained by the XRD method is as small as 100 to 500 angstroms, and is originally used as the nickel powder used in the present invention. It was considered unsuitable. However, when the crystallite size of the nickel powder obtained by the wet reduction method is less than 300 angstroms, the crystallite size can be reduced by carrying out crystal growth by heating and holding, preferably by the method described in Japanese Patent Application No. 10-268160. Can be made 300 angstroms or more, and it has been found that the effect of improving the oxidation resistance can be realized more reliably.
Crystal growth can also be realized by heating and holding at 400 to 600 ° C. in a non-oxidizing atmosphere after the addition treatment of Ti and / or Si.
[0011]
(2) containing 0.02% by mass to 1% by mass of one or both of Ti and Si;
If the crystallite size is 300 angstroms or more, the larger the crystallite size, the better. However, even with a large crystallite size nickel powder, the above problem cannot be overcome unless the oxidation resistance of the particle surface is increased. The present inventors have found that the oxidation resistance of the nickel powder particle surface is improved by allowing 0.02% by mass to 1% by mass of either or both of Ti and Si on the nickel particle surface. .
The effect of improving the oxidation resistance by adding Ti and / or Si is that a nickel oxide layer containing Ti and Si is formed on the particle surface due to the presence of these elements in the vicinity of the particle surface. It is estimated that progress can be suppressed.
These elements are added by suspending nickel powder in an aqueous solution, adding an organic compound containing Si or an organic compound containing Ti, and admixing the element to the surface of the nickel powder, followed by filtration and drying. Can be obtained.
[0012]
If the addition amount of Ti or Si is singly or in total less than 0.02% by mass, the above effect cannot be obtained. On the other hand, if it exceeds 1% by mass, nickel sintering may be inhibited, which is not preferable. . In particular, when the amount of Ti is large, there is a risk of changing the composition of the dielectric material of barium titanate as a counterpart, and the designed dielectric constant cannot be obtained.
[0013]
(3) The true specific gravity of the powder is not less than 8.2 ;
It was found that when the true specific gravity of the nickel powder exceeded 8.2, the shrinkage during sintering was reduced and breakage did not easily occur even with a 1 μm electrode. The higher the true density of nickel powder, the more advantageous .
(4) The ratio of particles having a particle size of at least twice the average particle size in SEM photo observation is 1/100 or less;
[0014]
As nickel powder with high true density, nickel powder having a large crystallite size by a vapor phase method is known. However, this nickel powder cannot avoid mixing particles having a size more than twice the average particle size due to the process characteristics.
When the electrode is thinned, these coarse particles cause the projection of the electrode, and the protruding portion of the electrode directly shortens the interlayer distance, so that dielectric breakdown is likely to occur, reducing the life and reliability of the capacitor. Therefore, it is not preferable. Further, the thinner the layer is, the thinner the dielectric thickness becomes, so that it becomes more sensitive to electrode protrusions. In general, the size of the coarse particles in question should not exceed the thickness of the designed electrode, but in practice, even if the size is smaller than that, the difference from the average particle size When many large particles are present, they often cause protrusions. As a result of the study, the present inventors have found that many particles having a particle size more than twice the average particle size among the particles contained in the nickel powder are likely to cause electrode protrusions, in other words, the average particle size It has been found that dielectric breakdown in the electrode can be prevented when the particles having a particle size of 2 times or more are less than 1/100 of the total.
[0015]
Practically, since the thickness of the electrode is 2 to 3 μm after firing, the average particle diameter by SEM photograph observation is 1 μm or less, and the amount of particles having a particle diameter of 2 μm or more, which is twice that, is minimized. Specifically, it has been found that this problem can be solved by setting it to 1/100 or less.
[0016]
【Example】
[Example 1]
Nickel powder (Sumitomo Metal Mining Co., Ltd.) having a crystallite size of 800 angstroms is suspended in an aqueous solution and a titanate coupling agent (KR-ET manufactured by Ajinomoto Co., Inc.) is added, pH 7 The nickel powder having a Ti content of 500 ppm was obtained by stirring and holding at room temperature to adsorb Ti.
This nickel powder has a true specific gravity of 8.5, an average particle size of 0.56 μm by SEM photographic diagonal method, no presence of particles of 1 μm or more, and an oxidized weight when kept at 400 ° C. in air for 2 hours. The increase rate was 11%.
The nickel powder was used to investigate the shrinkage behavior at 1000 ° C. by thermomechanical analysis (TMA) and observe the electrode state after firing the coating film. The results are shown in Table 1 below.
[0017]
[Example 2]
Nickel powder (made by Sumitomo Metal Mining Co., Ltd.) with a crystallite size of 800 angstroms is suspended in an aqueous solution, and an ethanol solution of γ-glycidoxypropyltrimethoxysilane, which is a kind of silane coupling agent, is added. The mixture was stirred and held at pH 10 and 70 ° C., and Si was adsorbed to obtain nickel powder having a Si content of 500 ppm.
This nickel powder has a true specific gravity of 8.8, an average particle diameter of 0.56 μm by SEM photographic diagonal method, and no particles larger than 1 μm are observed, and an oxidized weight when kept at 400 ° C. in air for 2 hours. The increase rate was 8%.
Using this nickel powder, the shrinkage behavior at 1000 ° C. by TMA and the electrode state after firing the coating film were observed. The results are also shown in Table 1 below.
[0018]
[Example 3]
A nickel powder having a Ti content of 500 ppm was obtained in the same manner as in Example 1 except that a nickel powder having a crystallite size of 150 Å was used. This nickel powder was heated and held at 600 ° C. for 1 hour in an air stream of 2% hydrogen and 98% nitrogen, and the crystallite size was set to 900 Å. This nickel powder has a true specific gravity of 8.5, an average particle size of 0.58 μm by SEM photographic diagonal method, no presence of particles of 1 μm or more, and an oxidized weight when held at 400 ° C. in air for 2 hours. The increase rate was 13%.
Investigation of the shrinkage behavior of this nickel powder by TMA at 1000 ° C. and the electrode state after firing the coating film were observed. The results are also shown in Table 1 below.
[0019]
[Comparative Example 1]
When the crystallite size is 700 angstroms, the true specific gravity is 7.9, the average particle diameter is 0.56 μm by the SEM photograph diagonal line method, and the presence of particles of 1 μm or more is not observed, and when kept at 400 ° C. in air for 2 hours Investigation of shrinkage behavior at 1000 ° C by TMA and electrode state after coating film firing using nickel powder (Sumitomo Metal Mining Co., Ltd.) with an increase in oxidized weight of 20% and a Ti and Si content of less than 10 ppm Was observed. The results are also shown in Table 1 below.
[0020]
[Comparative Example 2]
The crystallite size is 800 angstroms, the true specific gravity is 8.5, the average particle size of primary particles by SEM photo diagonal method is 0.57 μm, contains many secondary aggregates of 1 μm or more, and kept in air at 400 ° C. for 2 hours. Of the shrinkage behavior at 1000 ° C. by TMA and the electrode after firing the coating film using nickel powder (manufactured by Sumitomo Metal Mining Co., Ltd.) having an increase in oxidized weight of 11% and a Ti content of 500 ppm. The condition was observed. The results are also shown in Table 1 below.
[0021]
[Comparative Example 3]
When the crystallite size is 700 angstroms, the true specific gravity is 8.5, the average particle size is 0.56 μm by SEM photograph diagonal line method, and the presence of particles of 1 μm or more is not observed, and when kept in air at 400 ° C. for 2 hours Investigation of shrinkage behavior at 1000 ° C. by TMA and electrode state after coating film firing using nickel powder (Sumitomo Metal Mining Co., Ltd.) with an increase in oxidized weight of 20% and a Ti and Si content of less than 10 ppm Was observed. The results are also shown in Table 1 below.
[0022]
[Table 1]
[0023]
As can be seen from Table 1, in the examples of the present invention, the shrinkage rate at 1000 ° C. was 15% or less, no crack was generated, and there was no breakage of the nickel electrode. On the other hand, in Comparative Examples 1 and 2, the shrinkage ratios were as high as 20% and 25%, and cracks occurred and the nickel electrodes were interrupted. In Comparative Example 3, the shrinkage ratio was 15%, but the nickel electrodes were interrupted. It has occurred.
[0024]
【The invention's effect】
As described above, according to the present invention, in the production process of a multilayer ceramic capacitor, it is possible to prevent a function stop as a capacitor due to electrode breakage and a decrease in lifetime and reliability due to dielectric breakdown, and an extremely effective multilayer ceramic capacitor. The nickel powder for internal electrode paste can be provided.
Claims (1)
1)前記ニッケル粉は、空気中400℃で2時間保持したときの酸化重量増加率が15%未満であり、
2)前記ニッケル粉は、XRD法により求めた結晶子サイズが300オングストローム以上であり、
3)前記ニッケル粉の粉末の真比重が8.5以上であり、且つ、
4)前記ニッケル粉のSEM写真観察において、その平均粒径の2倍以上の粒径を有する粒子が、全体の100分の1以下、
であることを特徴とする積層セラミックコンデンサーの内部電極ペースト用ニッケル粉。A nickel powder containing at least one of Ti and Si at least 0.02 to 1% by mass on the surface thereof,
1) The nickel powder has an oxidation weight increase rate of less than 15% when held in air at 400 ° C. for 2 hours,
2) The nickel powder has a crystallite size determined by an XRD method of 300 angstroms or more,
3) The true specific gravity of the nickel powder powder is 8.5 or more, and
4) In the SEM photograph observation of the nickel powder, particles having a particle size of twice or more of the average particle size are 1/100 or less of the total,
Nickel powder for internal electrode paste of multilayer ceramic capacitor, characterized in that
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Cited By (3)
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EP1860695A2 (en) | 2006-05-24 | 2007-11-28 | Raytheon Company | System and method of jet impingement cooling with extended surfaces |
KR20190121167A (en) | 2018-09-05 | 2019-10-25 | 삼성전기주식회사 | Multilayer ceramic electronic component |
KR20200043323A (en) | 2018-09-05 | 2020-04-27 | 삼성전기주식회사 | Multilayer ceramic electronic component |
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US6954350B2 (en) | 2002-10-15 | 2005-10-11 | Matsushita Electric Industrial Co., Ltd. | Ceramic layered product and method for manufacturing the same |
US20130107419A1 (en) * | 2011-10-28 | 2013-05-02 | Kemet Electronics Corporation | Multilayered ceramic capacitor with improved lead frame attachment |
JP5986117B2 (en) * | 2012-02-08 | 2016-09-06 | Jx金属株式会社 | Surface-treated metal powder and method for producing the same |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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EP1860695A2 (en) | 2006-05-24 | 2007-11-28 | Raytheon Company | System and method of jet impingement cooling with extended surfaces |
KR20190121167A (en) | 2018-09-05 | 2019-10-25 | 삼성전기주식회사 | Multilayer ceramic electronic component |
KR20200043323A (en) | 2018-09-05 | 2020-04-27 | 삼성전기주식회사 | Multilayer ceramic electronic component |
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