JP2010077501A - Nickel-copper alloy powder, method for producing the same, conductive paste and electronic component - Google Patents
Nickel-copper alloy powder, method for producing the same, conductive paste and electronic component Download PDFInfo
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- H—ELECTRICITY
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- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
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- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
- B22F1/054—Nanosized particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0425—Copper-based alloys
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- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0433—Nickel- or cobalt-based alloys
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- C22C19/00—Alloys based on nickel or cobalt
- C22C19/002—Alloys based on nickel or cobalt with copper as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
- C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
- H01B1/026—Alloys based on copper
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
Abstract
Description
本発明は、微粒のニッケル−銅合金粉末とその製法、および、この合金粉末を用いた導体ペースト、並びに、その導体ペーストを用いて形成される導体膜を備えた電子部品に関する。 The present invention relates to a fine nickel-copper alloy powder and a manufacturing method thereof, a conductor paste using the alloy powder, and an electronic component including a conductor film formed using the conductor paste.
近年、電子機器の小型化および薄型化に伴い、積層セラミックコンデンサ、インダクタおよびＩＣパッケージなどの電子部品は、これらを構成する誘電体層などの絶縁体の薄層化および多層化が図られている。この場合、絶縁体の薄層化に伴って、その表面に形成される導体膜との厚み差が小さくなってきていることから、導体膜の厚みによる段差に起因して絶縁体と導体膜との間でデラミネーション等の不良が発生しやすくなってきている。そのため絶縁体の表面に設けられる導体膜についても薄層化の要求が高まっており、以下に示すように、大量生産に適した液相法を用いた微粒の卑金属粉末の製法が提案されている。 2. Description of the Related Art In recent years, electronic components such as multilayer ceramic capacitors, inductors, and IC packages have been made thinner and multi-layered with insulators such as dielectric layers, etc., as electronic devices have become smaller and thinner. . In this case, as the thickness of the insulator is reduced, the difference in thickness from the conductor film formed on the surface of the insulator has been reduced. Delamination and other defects are likely to occur between the two. Therefore, there is an increasing demand for thinning the conductor film provided on the surface of the insulator. As shown below, a method for producing fine base metal powder using a liquid phase method suitable for mass production has been proposed. .
例えば、出発原料として水酸化ニッケルを用い、これにアルカリ土類金属の酸化物を混合し、水素還元雰囲気中にて、８００℃以上の温度に加熱することにより、１粒子の最大投影直径が５００〜３０００ｎｍで、厚みが５０〜９００ｎｍの扁平な形状のニッケル粉末を得る技術が開示されている（例えば、特許文献１参照）。 For example, nickel hydroxide is used as a starting material, and an alkaline earth metal oxide is mixed therewith and heated to a temperature of 800 ° C. or higher in a hydrogen reduction atmosphere, whereby the maximum projected diameter of one particle is 500. A technique for obtaining a flat nickel powder having a thickness of ˜3000 nm and a thickness of 50 to 900 nm is disclosed (for example, see Patent Document 1).
また、出発原料として塩化ニッケルを用い、これにチタンイソプロポキシド、水酸化バリウムおよび水酸化ナトリウムを加え、これらをイオン交換水に溶解させて、６０℃にて、１時間放置することにより、粒子径１００ｎｍのニッケルを主成分とする卑金属粉末を得る技術が開示されている（例えば、特許文献２参照）。 Further, by using nickel chloride as a starting material, titanium isopropoxide, barium hydroxide and sodium hydroxide were added thereto, and these were dissolved in ion-exchanged water and left at 60 ° C. for 1 hour, whereby particles were obtained. A technique for obtaining a base metal powder mainly composed of nickel having a diameter of 100 nm is disclosed (for example, see Patent Document 2).
さらに、出発原料として、水酸化ニッケルにパラジウムなどの貴金属を添加し、これをエチレングリコール溶液中に投入して加熱して還元することにより、平均粒径が２０〜１００ｎｍで、かつ粒径のばらつきの小さいニッケル粉末を得る技術が開示されている（例えば、特許文献３参照）。 Furthermore, by adding a noble metal such as palladium to nickel hydroxide as a starting material, this is put into an ethylene glycol solution, heated and reduced, so that the average particle size is 20 to 100 nm and the particle size varies. Has been disclosed (see, for example, Patent Document 3).
一方、銅については、平均粒径が１〜１００μｍの微粉末を得る手法として、酢酸を含む水溶液中で銅化合物をヒドラジンで還元する方法が開示されている（例えば、特許文献４参照）。
しかしながら、これまで平均粒径が３０ｎｍ以下で、かつ高純度のニッケルと銅とを含む合金粉末、および、このような超微粒で高純度の合金粉末を製造する方法については何ら知られていない。 However, nothing is known about an alloy powder having an average particle diameter of 30 nm or less and containing high-purity nickel and copper, and a method for producing such ultrafine and high-purity alloy powder.
従って本発明は、超微粒のニッケル−銅合金粉末と、このような超微粒の合金粉末を大量に生産するための製法を提供することを目的とするものであり、また、こうして得られた超微粒のニッケル−銅合金粉末を導体ペーストに用いて、絶縁体の表面に薄層の導体膜を有し、デラミネーション等の発生を抑制できる電子部品を提供することを目的とする。 Accordingly, an object of the present invention is to provide an ultrafine nickel-copper alloy powder and a production method for mass-producing such an ultrafine alloy powder. An object of the present invention is to provide an electronic component that uses fine nickel-copper alloy powder as a conductor paste, has a thin conductor film on the surface of an insulator, and can suppress the occurrence of delamination or the like.
本発明のニッケル−銅合金粉末は、ニッケルと銅とを９９質量％以上含有する合金粉末であって、平均粒径が５〜３０ｎｍであり、Ｘ線回折パターンにおいて、前記ニッケルと前記銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、前記ニッケルの酸化物の主ピークおよび前記銅の酸化物の主ピークのうちの最も強い回折強度の割合が、前記ニッケルと前記銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の１０％以下であることを特徴とする。 The nickel-copper alloy powder of the present invention is an alloy powder containing 99% by mass or more of nickel and copper, and has an average particle size of 5 to 30 nm. In the X-ray diffraction pattern, the nickel-copper alloy powder is obtained from the nickel and the copper. The ratio of the strongest diffraction intensity among the main peak of the alloy having a hexagonal close-packed structure (hcp), the main peak of the nickel oxide, and the main peak of the copper oxide is from the nickel and the copper. It is characterized by being 10% or less of the diffraction intensity of the main peak of an alloy having a cubic close-packed structure (ccp).
また、本発明では、そのニッケル−銅合金粉末の平均粒径が７〜１０ｎｍであることが望ましい。 Moreover, in this invention, it is desirable that the average particle diameter of the nickel-copper alloy powder is 7 to 10 nm.
また、本発明のニッケル−銅合金粉末の製法は、（ａ）ニッケルおよび銅の硝酸塩と、オレイン酸ナトリウムまたはマレイン酸ナトリウムとを、水および該水よりも極性の低い溶媒との混合溶媒中に溶解してニッケルおよび銅を含有する溶液を調製する工程と、（ｂ）該溶液から、前記ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る工程と、（ｃ）前記ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を、還元雰囲気中にて、２５０〜４００℃の温度で加熱する工程とを具備することを特徴とする。 The method for producing the nickel-copper alloy powder of the present invention comprises (a) nickel and copper nitrate, sodium oleate or sodium maleate in a mixed solvent of water and a solvent having a polarity lower than that of water. Dissolving and preparing a solution containing nickel and copper; (b) obtaining from the solution a precursor of oleic acid or maleic acid containing nickel and copper; and (c) the nickel And a step of heating a precursor of oleic acid or maleic acid containing copper at a temperature of 250 to 400 ° C. in a reducing atmosphere.
また、本発明のニッケル−銅合金粉末の製法では、前記水よりも極性の低い溶媒として、ヘキサンおよびエタノールを用いることが望ましい。 Moreover, in the manufacturing method of the nickel-copper alloy powder of this invention, it is desirable to use hexane and ethanol as a solvent whose polarity is lower than the said water.
また、本発明の導体ペーストは、上記ニッケル−銅合金粉末と有機ビヒクルとを含むことを特徴とする。 Moreover, the conductor paste of this invention is characterized by including the said nickel-copper alloy powder and an organic vehicle.
また、本発明の電子部品は、絶縁体と該絶縁体の表面に設けられた上記導体ペーストを焼成して形成された導体膜とを具備していることを特徴とする。 The electronic component of the present invention includes an insulator and a conductor film formed by firing the conductor paste provided on the surface of the insulator.
本発明のニッケル−銅合金粉末および導体ペーストによれば、極めて薄い導体膜を形成できる。このため絶縁体と導体膜とが多層に積層された電子部品においてデラミネーション等の発生を抑制できる。 According to the nickel-copper alloy powder and conductor paste of the present invention, an extremely thin conductor film can be formed. For this reason, generation | occurrence | production of a delamination etc. can be suppressed in the electronic component by which the insulator and the conductor film were laminated | stacked in multiple layers.
また、本発明のニッケル−銅合金粉末の製法によれば、極めて薄い導体膜を形成することが可能な超微粒で高純度のニッケル−銅合金粉末を大量生産の工程で容易に得ることができる。 Further, according to the method for producing a nickel-copper alloy powder of the present invention, an ultrafine and high-purity nickel-copper alloy powder capable of forming an extremely thin conductor film can be easily obtained in a mass production process. .
本発明の電子部品によれば、さらなる小型化および薄型化を図ることが可能になる。 According to the electronic component of the present invention, it is possible to further reduce the size and thickness.
図１は、本発明のニッケル−銅合金粉末の一例を示す電子顕微鏡写真である。本発明のニッケル−銅合金粉末（以下、合金粉末という）は、ニッケルと銅とを９９質量％以上含むものである。この場合、ニッケルと銅とは全率固溶を示す任意の組成を有するものであり、このためニッケルの融点（１４５３℃）と銅の融点（１０８３℃）との間で融点を任意に変化させることが可能となる。 FIG. 1 is an electron micrograph showing an example of the nickel-copper alloy powder of the present invention. The nickel-copper alloy powder (hereinafter referred to as alloy powder) of the present invention contains 99% by mass or more of nickel and copper. In this case, nickel and copper have an arbitrary composition showing a complete solid solution, and therefore the melting point is arbitrarily changed between the melting point of nickel (1453 ° C.) and the melting point of copper (1083 ° C.). It becomes possible.
この場合、絶縁体としてチタン酸バリウムを主成分とする材料を用いる場合にはニッケルの含有量が５０質量％以上、特に７０質量％以上であるものを用いるのが望ましく、一方、絶縁体に微粒の原料粉末を用いるかまたは多くのガラス成分等の焼結助剤を含み１０００℃以下の温度での焼成を必要とする場合銅の含有量が５０質量％よりも多いことが望ましい。こうして微粒の誘電体粉末などを用いた場合や焼結助剤等の添加量により焼成温度が変化した場合においても、設定される焼成温度に合わせた合金組成で焼成することが可能になる。また、ニッケルの含有量が５０モル％よりも少ないニッケル−銅合金は透磁率を低くできることから高周波部品用の導体膜としても有用となる。 In this case, when a material mainly composed of barium titanate is used as the insulator, it is desirable to use a nickel content of 50% by mass or more, particularly 70% by mass or more. When the raw material powder is used or a sintering aid such as many glass components is included and firing at a temperature of 1000 ° C. or less is required, the copper content is preferably more than 50% by mass. Thus, even when a fine dielectric powder or the like is used, or when the firing temperature changes depending on the addition amount of a sintering aid or the like, firing can be performed with an alloy composition that matches the set firing temperature. Further, a nickel-copper alloy having a nickel content of less than 50 mol% can be used as a conductor film for high-frequency components because the permeability can be lowered.
本発明の合金粉末は不可避不純物を除き、元素としてニッケルと銅とを合計で９９質量％以上含有するものであり、これによりニッケルと銅との合金において立方最密構造の割合の多い合金粉末を得ることができる。一方、合金粉末中のニッケルおよび銅の含有量が９９質量％よりも少ない場合には、異相が生成しやすくなるためニッケル−銅の立方最密構造の割合が低下するため焼結時に凝集等が起こりやすく、絶縁体との積層体を形成した場合にデラミネーションが発生しやすくなるおそれがある。 The alloy powder of the present invention contains 99% by mass or more of nickel and copper as elements in total, excluding inevitable impurities, whereby an alloy powder having a high cubic close-packed structure ratio in an alloy of nickel and copper can be obtained. Obtainable. On the other hand, when the content of nickel and copper in the alloy powder is less than 99% by mass, a heterogeneous phase is likely to be formed, so that the proportion of the nickel-copper cubic close-packed structure is reduced, so that aggregation or the like occurs during sintering. It tends to occur, and there is a risk that delamination is likely to occur when a laminate with an insulator is formed.
なお、合金粉末中に含まれるニッケルおよび銅の合計の含有量はそれぞれの標準液を用いてＩＣＰ（Inductively coupled Plasma）発光分光分析により求める。 The total content of nickel and copper contained in the alloy powder is determined by ICP (Inductively coupled Plasma) emission spectroscopic analysis using each standard solution.
また、ニッケルと銅との合金はニッケルのみの場合または銅のみの場合に比較して耐酸化性が増すことから、例えば、大気中など酸素濃度の高い雰囲気で脱脂する温度を高められることから、これによっても積層型の電子部品におけるデラミネーションを抑制できるという利点がある。 In addition, since the oxidation resistance of an alloy of nickel and copper is increased compared to the case of nickel alone or copper alone, for example, the degreasing temperature can be increased in an atmosphere with a high oxygen concentration such as in the atmosphere. This also has an advantage that delamination in the multilayer electronic component can be suppressed.
さらに、ニッケルおよび銅は、金、銀、パラジウムおよび白金などの貴金属に比較して安価であることから、内部電極層が多層化された積層型の電子部品を構成する導体膜に適用した場合に製造コストを低減できるという利点がある。 Furthermore, since nickel and copper are less expensive than noble metals such as gold, silver, palladium, and platinum, when applied to a conductor film that constitutes a multilayer electronic component with a multilayered internal electrode layer There is an advantage that the manufacturing cost can be reduced.
本発明の合金粉末は平均粒径が５〜３０ｎｍである。合金粉末の平均粒径が５ｎｍ以上であると結晶性が高くなり、不均一な反応が抑えられ加熱時の凝集を抑制できる。合金粉末の平均粒径が３０ｎｍ以下であると、誘電体層等の絶縁体の表面に、きわめて薄い導体膜を形成できることから導体膜による段差を低減でき、このため絶縁体と導体膜とが多層に積層された電子部品においてデラミネーション等の発生を抑制できる。 The alloy powder of the present invention has an average particle size of 5 to 30 nm. When the average particle size of the alloy powder is 5 nm or more, the crystallinity is increased, nonuniform reaction is suppressed, and aggregation during heating can be suppressed. If the average particle size of the alloy powder is 30 nm or less, an extremely thin conductor film can be formed on the surface of an insulator such as a dielectric layer, so that the step difference due to the conductor film can be reduced. Therefore, the insulator and the conductor film are multilayered. It is possible to suppress the occurrence of delamination or the like in the electronic component laminated on the substrate.
そして、より好ましい合金粉末の平均粒径としては７〜１０ｎｍが良い。合金粉末の平均粒径がこの範囲であると合金粉末の反応性をより安定化できることから凝集が抑制され薄層化が容易になり、デラミネーションの発生をさらに低減することが可能になる。 A more preferable average particle diameter of the alloy powder is 7 to 10 nm. When the average particle diameter of the alloy powder is within this range, the reactivity of the alloy powder can be further stabilized, so that aggregation is suppressed, thinning is facilitated, and the occurrence of delamination can be further reduced.
これに対して、平均粒径が５ｎｍよりも小さいと結晶性が低くなり、立方最密構造の割合が低下し、さらには、合金粉末の形状が不揃いになりやすいことから不均一な反応が起こりやすく、このため凝集しやくなり、その結果、導体膜を薄層化することが困難となる。 On the other hand, when the average particle size is smaller than 5 nm, the crystallinity is lowered, the ratio of the cubic close-packed structure is lowered, and furthermore, the shape of the alloy powder is likely to be uneven, causing a non-uniform reaction. As a result, it tends to agglomerate, and as a result, it is difficult to thin the conductor film.
合金粉末の平均粒径が３０ｎｍよりも大きい場合には、誘電体層等の絶縁体の表面に薄層の導体膜を形成することが困難となり、このため絶縁体と導体膜とが多層に積層された電子部品において、導体膜の厚みによる段差が大きくなり、デラミネーション等の不良が発生しやすくなる。 When the average particle size of the alloy powder is larger than 30 nm, it is difficult to form a thin conductor film on the surface of an insulator such as a dielectric layer. For this reason, the insulator and the conductor film are laminated in multiple layers. In the manufactured electronic component, a step due to the thickness of the conductor film is increased, and defects such as delamination are likely to occur.
なお、本発明において、合金粉末の平均粒径とは、この合金粉末を構成する個々の粒子を複数個集めたときの各粒子径の平均値のことである。この場合、合金粉末の平均粒径は、走査型電子顕微鏡を用いて合金粉末の写真を撮り、その写真上で粒子が約３０個入る円を描き、円内および円周にかかった粒子を選択し、各粒子の輪郭を画像処理し、各粒子を円と見立てて円相当径を算出し、その平均値より求める。 In the present invention, the average particle diameter of the alloy powder is an average value of the particle diameters when a plurality of individual particles constituting the alloy powder are collected. In this case, the average particle diameter of the alloy powder is determined by taking a photograph of the alloy powder using a scanning electron microscope, drawing a circle containing about 30 particles on the photograph, and selecting the particles that fall within and around the circle. Then, the contour of each particle is image-processed, each particle is regarded as a circle, a circle equivalent diameter is calculated, and the average value is obtained.
図２は、本発明の合金粉末のＸ線回折パターンの例である。図２に示すＸ線回折パターンのうち（ａ）は、実施例における試料Ｎｏ．３の加熱温度が３００℃の場合、（ｂ）は、実施例における試料Ｎｏ．６の加熱温度が４００℃の場合である。図２の（ａ）のＸ線回折パターンでは、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの最も強い回折強度を示したものはニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金であったため、この六方最密構造（ｈｃｐ）のピークを選択して、立方最密構造（ｃｃｐ）を有する合金の主ピークに対する割合を求めたものである。図２の（ｂ）のＸ線回折パターンについては、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの最も強い回折強度を示したものは銅の酸化物であったため、この銅の酸化物の主ピークを選択して、立方最密構造（ｃｃｐ）を有する合金の主ピークに対する割合を求めたものである。 FIG. 2 is an example of an X-ray diffraction pattern of the alloy powder of the present invention. Of the X-ray diffraction patterns shown in FIG. When the heating temperature of No. 3 is 300 ° C., FIG. This is a case where the heating temperature of 6 is 400 ° C. In the X-ray diffraction pattern of FIG. 2 (a), the main peak of an alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), the main peak of nickel oxide, and the main peak of copper oxide Since the alloy having the strongest diffraction intensity was an alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), the peak of this hexagonal close-packed structure (hcp) was selected and a cubic close-packed structure ( The ratio with respect to the main peak of the alloy having (ccp) is obtained. As for the X-ray diffraction pattern of FIG. 2B, the main peak of the alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), the main peak of the nickel oxide, and the main peak of the copper oxide. Since the one showing the strongest diffraction intensity was a copper oxide, the main peak of this copper oxide was selected, and the ratio of the alloy having a cubic close-packed structure (ccp) to the main peak was determined. Is.
本発明の合金粉末は、Ｘ線回折パターンにおいて、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの最も強い回折強度の割合が、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の１０％以下である。 In the X-ray diffraction pattern, the alloy powder of the present invention includes a main peak of an alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), a main peak of nickel oxide, and a main peak of copper oxide. The ratio of the strongest diffraction intensity is 10% or less of the diffraction intensity of the main peak of an alloy composed of nickel and copper and having a cubic close-packed structure (ccp).
本発明の合金粉末は、上述のような平均粒径を有していても、金属として高い最密充填構造を有する立方最密構造の割合が多いために、金属のすべり面が現れやすいことから展性や延性に富み、かつ導電性の高いものを得ることができる。 Even if the alloy powder of the present invention has the average particle size as described above, since the ratio of the cubic close-packed structure having a high close-packed structure as a metal is large, a metal slip surface is likely to appear. A product having high malleability and ductility and high conductivity can be obtained.
この場合、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの最も強い回折強度の割合がニッケルと銅とからなる立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の５％以下であることがより望ましく、これによりニッケル−銅合金粉末の焼結体中における異相の生成を抑制でき、これにより展性や延性および導電性を高めることが可能になる。 In this case, the ratio of the strongest diffraction intensity among the main peak of the alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), the main peak of nickel oxide, and the main peak of copper oxide is nickel and copper. It is more desirable to be 5% or less of the diffraction intensity of the main peak of an alloy having a cubic close-packed structure (ccp) made of copper, and this can suppress the formation of heterogeneous phases in the sintered body of the nickel-copper alloy powder. This makes it possible to improve malleability, ductility and conductivity.
これに対して、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの最も強い回折強度の割合が、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度に対して１０％よりも高い場合には展性や延性および高い導電率を得ることが困難となる。 On the other hand, the ratio of the strongest diffraction intensity among the main peak of an alloy composed of nickel and copper and having a hexagonal close-packed structure (hcp), the main peak of nickel oxide, and the main peak of copper oxide is When the diffraction intensity of the main peak of an alloy composed of nickel and copper and having a cubic close-packed structure (ccp) is higher than 10%, it becomes difficult to obtain malleability, ductility and high conductivity.
次に、本発明のニッケル−銅合金粉末（以下、合金粉末という）の製法について説明する。 Next, a method for producing the nickel-copper alloy powder (hereinafter referred to as alloy powder) of the present invention will be described.
（ａ）工程では、ガラス製容器に、それぞれ純度が９９％以上（質量比）のニッケルおよび銅の硝酸塩と、オレイン酸ナトリウムまたはマレイン酸ナトリウムとを入れ、さらに水および水よりも極性の低い２種の溶媒とを加えて、これら３種の混合溶媒中にニッケルおよび銅の成分が溶解したニッケル−銅を含有する溶液を調製する。 In the step (a), nickel and copper nitrates each having a purity of 99% or more (mass ratio) and sodium oleate or sodium maleate are placed in a glass container, and water and water 2 having a lower polarity than water 2 The seed solvent is added to prepare a solution containing nickel-copper in which the components of nickel and copper are dissolved in the mixed solvent of these three kinds.
本発明ではニッケルおよび銅の硝酸塩として硝酸ニッケルおよび硝酸銅を用いる。これらの硝酸塩は水和物であっても良いが、高純度の合金粉末が得られるという理由から、用いる硝酸塩の純度は９９％以上であることが好ましい。 In the present invention, nickel nitrate and copper nitrate are used as nickel and copper nitrates. These nitrates may be hydrates, but the purity of the nitrate used is preferably 99% or more because high purity alloy powder can be obtained.
また、添加剤として、オレイン酸ナトリウムまたはマレイン酸ナトリウムを、硝酸塩１００質量部に対して５〜２０質量部添加する。オレイン酸ナトリウムまたはマレイン酸ナトリウムの添加量が上記範囲であると、反応終了後に生成するニッケルおよび銅を含む前駆体の凝集を抑制できるとともに、前駆体を構成する有機物の分解反応を促進でき、微粒の合金粉末が得られるという利点がある。 Moreover, 5-20 mass parts of sodium oleate or sodium maleate is added as an additive with respect to 100 mass parts of nitrates. When the addition amount of sodium oleate or sodium maleate is within the above range, aggregation of the precursor containing nickel and copper generated after the completion of the reaction can be suppressed, and the decomposition reaction of organic substances constituting the precursor can be promoted. There is an advantage that an alloy powder can be obtained.
また、本発明の合金粉末の製法では、上記ニッケルおよび銅を含む硝酸塩を溶解させ、かつ反応終了後にこれらの金属成分を含む前駆体を形成するための溶媒として、水と、水よりも極性の低い２種の溶媒を用いる。 Moreover, in the method for producing the alloy powder of the present invention, water and a solvent more polar than water are used as a solvent for dissolving the nitrate containing nickel and copper and forming a precursor containing these metal components after completion of the reaction. Two lower solvents are used.
第１の溶媒である水（極性：２１）はイオン交換水を用いるのが良い。水よりも極性の低い溶媒である第２の溶媒としては、ブチルアルコール（極性：１０．７）、ヘキサン（極性：７．３）およびオクタン（極性：７．０）から選ばれる１種の溶媒を用いることが好ましい。なお、溶媒の極性とは、成分原子の電気陰性度の違いのために電子雲の分布が偏り、正負の電荷の重心が一致しないで双極子が形成された状態を表す量であり、溶媒のモル蒸発エネルギーを１モル当たりの体積で除した値の平方根で表される値である。 Water (polarity: 21) that is the first solvent is preferably ion-exchanged water. As the second solvent which is a solvent having a polarity lower than that of water, one solvent selected from butyl alcohol (polarity: 10.7), hexane (polarity: 7.3) and octane (polarity: 7.0) Is preferably used. The polarity of the solvent is an amount representing the state in which the distribution of electron clouds is biased due to the difference in electronegativity of component atoms, and the dipoles are formed without the centroids of positive and negative charges being coincident. It is a value represented by the square root of the value obtained by dividing the molar evaporation energy by the volume per mole.
また、水よりも極性の低い第３の溶媒としては、水と第２の溶媒との中間の極性を持つ溶媒を選択するのがよく、例えば、メチルアルコール、エチルアルコールおよびプロピルアルコールから選ばれる１種の溶媒をもちいることが好ましい。 In addition, as the third solvent having a polarity lower than that of water, a solvent having an intermediate polarity between water and the second solvent is preferably selected. For example, 1 selected from methyl alcohol, ethyl alcohol, and propyl alcohol. It is preferable to use a seed solvent.
本発明の合金粉末の製法において、極性の異なる３種の溶媒を用いるのは以下の理由からである。第１の溶媒として、極性の高い水を溶媒として用いるのはニッケルおよび銅を含む硝酸塩を溶解し易く、また、後述のオレイン酸ナトリウムまたはマレイン酸ナトリウムに含まれるナトリウム成分を水に溶解させておくことができるからである。第２の溶媒として水よりも極性の低いブチルアルコール、ヘキサンおよびオクタンから選ばれる１種の溶媒を用いるのは、上述のオレイン酸ナトリウムまたはマレイン酸ナトリウムが溶解しやすく、またオレイン酸ナトリウムまたはマレイン酸ナトリウムを核として形成されるニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体が形成されすいからである。 In the manufacturing method of the alloy powder of the present invention, three solvents having different polarities are used for the following reason. The use of highly polar water as the first solvent facilitates dissolution of nitrates including nickel and copper, and the sodium component contained in sodium oleate or sodium maleate described below is dissolved in water. Because it can. The use of one solvent selected from butyl alcohol, hexane, and octane, which is less polar than water, as the second solvent facilitates dissolution of the above-mentioned sodium oleate or sodium maleate, and also provides sodium oleate or maleic acid. This is because a precursor of oleic acid or maleic acid containing nickel and copper formed with sodium as a nucleus is formed.
さらに、水と第２の溶媒との中間の極性を有する第３の溶媒を用いるのは、第１の溶媒である水と第２の溶媒であるメチルアルコール（極性：１２．９）、エチルアルコール（極性：１１．２）およびプロピルアルコール（極性：１１．５）から選ばれる１種の溶媒とを分離することなく均一に混合するためであり、これにより、水に溶解しやすいニッケルおよび銅の硝酸塩と第２の溶媒に溶解しやすいオレイン酸ナトリウムまたはマレイン酸ナトリウムとを均一に混合することが可能になる。 Furthermore, the third solvent having a polarity intermediate between water and the second solvent uses water as the first solvent and methyl alcohol (polarity: 12.9) as the second solvent, ethyl alcohol. (Polarity: 11.2) and a solvent selected from propyl alcohol (polarity: 11.5) are uniformly mixed without separation. It becomes possible to uniformly mix the nitrate and sodium oleate or sodium maleate that is easily dissolved in the second solvent.
図３は、本発明の合金粉末の製法における（ｂ）工程において、生成するオレイン酸の前駆体またはマレイン酸の前駆体が溶液中で分離した状態を示す模式図である。 FIG. 3 is a schematic view showing a state in which a precursor of oleic acid or a precursor of maleic acid produced is separated in a solution in the step (b) in the method for producing an alloy powder of the present invention.
（ｂ）工程では、ニッケルおよび銅を含有する溶液を放置して、これらの金属成分を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る。ニッケルおよび銅を含有する溶液を放置することにより、この金属含有溶液は、水と、ブチルアルコール、ヘキサンおよびオクタンから選ばれる１種の溶媒との間で分離していき、生成するオレイン酸の前駆体またはマレイン酸の前駆体が第２の溶媒中に生成する。このときオレイン酸の前駆体およびマレイン酸の前駆体は重合体となっている。 In the step (b), a solution containing nickel and copper is allowed to stand to obtain a precursor of oleic acid or maleic acid containing these metal components. By leaving the solution containing nickel and copper, the metal-containing solution is separated between water and one solvent selected from butyl alcohol, hexane and octane, and the precursor of oleic acid to be produced Or a precursor of maleic acid is formed in the second solvent. At this time, the precursor of oleic acid and the precursor of maleic acid are polymers.
ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を放置するときの条件は、ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体の収率を高めるとともに、これらの前駆体の加熱による分解性を高めるという理由から、温度１０〜５０℃にて１〜４８時間が好ましい。 The conditions when leaving the precursors of oleic acid or maleic acid containing nickel and copper to increase the yields of precursors of oleic acid or maleic acid containing nickel and copper as well as the precursors of these For the reason of improving the decomposability by heating the body, 1 to 48 hours are preferable at a temperature of 10 to 50 ° C.
次に、ガラス製容器の排出口を開けて分離した下層側の溶液を排出させて、ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を含む第２の溶媒のみを抽出する。この後、ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を含む溶液から溶媒を乾燥させてニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る。この後、水洗を行いアルカリ成分などのイオンを除去し、さらにエチルアルコールとヘキサンとの混合溶液を用いて除くことのできる有機成分を除去する。 Next, the lower side solution separated by opening the outlet of the glass container is discharged, and only the second solvent containing the precursor of oleic acid or nickel acid containing nickel and copper is extracted. Thereafter, the solvent is dried from a solution containing a precursor of oleic acid containing nickel and copper or a precursor of maleic acid to obtain a precursor of oleic acid containing nickel and copper or a precursor of maleic acid. Thereafter, washing with water is performed to remove ions such as alkali components, and further, organic components that can be removed using a mixed solution of ethyl alcohol and hexane are removed.
次に、（ｃ）工程では、得られたニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を還元雰囲気（Ｎ２／５％Ｈ２）中にて２５０〜４００℃の温度で加熱する。加熱する温度が２５０℃よりも低くなると、オレイン酸の前駆体またはマレイン酸の前駆体の分解反応が促進されず前駆体が残留しやすくなる。一方、加熱する温度が４００℃よりも高い場合には、オレイン酸の前駆体またはマレイン酸の前駆体の分解反応が進み、残留する前駆体の量は少なくなるものの、得られる合金粉末が粒成長するため、超微粒の合金粉末を得ることが困難となる。この場合、得られる合金粉末において、立方最密構造の割合が高く、平均粒径を７〜１０ｎｍにできるという点で、加熱する温度は２７０〜３７０℃がより好ましい。 Next, in the step (c), the obtained precursor of oleic acid or maleic acid containing nickel and copper is reduced to a temperature of 250 to 400 ° C. in a reducing atmosphere (N 2 /5% H 2 ). Heat. When the heating temperature is lower than 250 ° C., the decomposition reaction of the precursor of oleic acid or the precursor of maleic acid is not accelerated and the precursor tends to remain. On the other hand, when the heating temperature is higher than 400 ° C., the decomposition reaction of the precursor of oleic acid or the precursor of maleic acid proceeds and the amount of the remaining precursor is reduced, but the obtained alloy powder grows. Therefore, it becomes difficult to obtain an ultrafine alloy powder. In this case, in the obtained alloy powder, the heating temperature is more preferably 270 to 370 ° C. in that the ratio of the cubic close-packed structure is high and the average particle size can be 7 to 10 nm.
上述したように、本発明の合金粉末の製法は、超微粒の合金粉末を得ることができるものであるが、この製法はニッケルおよび銅に限らず、コバルト，亜鉛，クロム，バナジウム，ニオブ，モリブデン，タングステン，チタン，ジルコニウムおよび鉄等の他の元素を主成分とする金属粉末ならびにこれらの合金粉末にも適用できるものである。 As described above, the manufacturing method of the alloy powder of the present invention can obtain an ultrafine alloy powder, but this manufacturing method is not limited to nickel and copper, but cobalt, zinc, chromium, vanadium, niobium, molybdenum. Further, the present invention can be applied to metal powders mainly composed of other elements such as tungsten, titanium, zirconium and iron, and alloy powders thereof.
次に、本発明の合金粉末を用いて得られる導体ペーストについて説明する。本発明の導体ペーストは上記の合金粉末と有機ビヒクルとを含むものである。このとき、必要に応じて、導体ペースト本来の導電性（低抵抗率）、半田耐熱性、接着強度等を著しく損なわない限りにおいて種々の無機添加剤を副成分として含ませることができる。有機ビヒクルとしては、例えば、エチルセルロース等のセルロース系高分子、エチレングリコールおよびジエチレングリコール誘導体、トルエン、キシレン、ミネラルスピリット、ブチルカルビトール、ターピネオール等の有機溶媒が挙げられる。また、無機添加剤としては、ガラス粉末、無機酸化物、その他種々のフィラー等が挙げられる。この場合、無機添加剤は平均粒径が合金粉末と同等かもしくはそれ以下の平均粒径を有するものが好ましい。 Next, the conductor paste obtained using the alloy powder of the present invention will be described. The conductor paste of the present invention contains the above alloy powder and an organic vehicle. At this time, if necessary, various inorganic additives can be included as subcomponents as long as the original conductivity (low resistivity), solder heat resistance, adhesive strength and the like of the conductor paste are not significantly impaired. Examples of the organic vehicle include cellulosic polymers such as ethyl cellulose, organic solvents such as ethylene glycol and diethylene glycol derivatives, toluene, xylene, mineral spirit, butyl carbitol, and terpineol. Examples of the inorganic additive include glass powder, inorganic oxide, and other various fillers. In this case, the inorganic additive preferably has an average particle diameter equal to or less than that of the alloy powder.
導体ペーストを調製する場合には、例えば、三本ロールミルその他の混練機を用いて、合金粉末および各種添加剤を有機ビヒクルとともに所定の配合比で直接混合し、相互に練り合わせる。 When preparing the conductor paste, for example, using a three-roll mill or other kneader, the alloy powder and various additives are directly mixed together with the organic vehicle at a predetermined blending ratio and kneaded with each other.
導体ペースト中の合金粉末の含有量は、特に限定するものではないが、好ましくは、主成分たる合金粉末の含有率がペースト全体の６０〜９５質量％となるように各材料を混練するのがよい。 The content of the alloy powder in the conductor paste is not particularly limited, but preferably, each material is kneaded so that the content of the alloy powder as a main component is 60 to 95% by mass of the entire paste. Good.
導体ペーストの調製に用いられる有機ビヒクルの添加量は、ペースト全体のほぼ１〜４０質量％となる量が適当であり、１〜２０質量％となる量が特に好ましい。また、無機添加剤としてガラス粉末やセラミック粉末を加える場合には、合金粉末１００質量部に対して５質量部以下の割合で添加するのが好ましい。 The amount of the organic vehicle used for the preparation of the conductor paste is suitably about 1 to 40% by mass of the total paste, and particularly preferably 1 to 20% by mass. Moreover, when adding glass powder and ceramic powder as an inorganic additive, it is preferable to add in the ratio of 5 mass parts or less with respect to 100 mass parts of alloy powder.
図４は、本発明の電子部品の一例として積層セラミックコンデンサを示す断面模式図である。本発明の導体ペーストを用いて、以下のようなコンデンサを形成できる。 FIG. 4 is a schematic cross-sectional view showing a multilayer ceramic capacitor as an example of the electronic component of the present invention. The following capacitors can be formed using the conductor paste of the present invention.
本発明における積層セラミックコンデンサはコンデンサ本体１の端部に外部電極２が設けられている。コンデンサ本体１は、絶縁体である誘電体層３（絶縁体３）と導体膜である内部電極層４とが交互に積層され構成されている。ここでの内部電極層４（導体膜４）は上述した本発明の導体ペーストによって形成されるものであり、その厚みは１００ｎｍ以下、特に、５０ｎｍ以下であることが望ましい。この場合、誘電体層３の厚みは絶縁性を確保できる厚みとして０．３μｍ以上、一方、電子部品の小型化に、より有利な厚みとして１μｍ以下である範囲が好ましい。これにより本発明の合金粉末を用いて得られる電子部品を薄型にでき、導体膜による段差を低減でき、これによりデラミネーションなどの発生を抑制することが可能になる。 In the multilayer ceramic capacitor according to the present invention, an external electrode 2 is provided at the end of the capacitor body 1. The capacitor body 1 is configured by alternately laminating dielectric layers 3 (insulators 3) that are insulators and internal electrode layers 4 that are conductor films. The internal electrode layer 4 (conductor film 4) here is formed by the above-described conductor paste of the present invention, and the thickness thereof is desirably 100 nm or less, particularly 50 nm or less. In this case, the thickness of the dielectric layer 3 is preferably in a range of 0.3 μm or more as a thickness that can ensure insulation, and 1 μm or less as a thickness that is more advantageous for downsizing of electronic components. As a result, an electronic component obtained by using the alloy powder of the present invention can be made thin, and a step due to the conductor film can be reduced, thereby suppressing the occurrence of delamination and the like.
次に、本発明の導体ペーストを用いて得られる電子部品の一例である積層セラミックコンデンサの製造方法について以下に説明する。 Next, the manufacturing method of the multilayer ceramic capacitor which is an example of the electronic component obtained using the conductor paste of this invention is demonstrated below.
まず、上述の導体ペーストを、焼成後に絶縁体となるセラミックグリーンシート上に印刷し、焼成後に導体膜となる導体パターンを形成する。このとき導体パターンの乾燥後の厚みは１００ｎｍ以下、特に、５０ｎｍ以下が好ましい。次いで、上述の導体パターンが形成されたセラミックグリーンシートを複数層積層し、加圧加熱して一体化させて母体積層体を形成する。 First, the above-described conductor paste is printed on a ceramic green sheet that becomes an insulator after firing, and a conductor pattern that becomes a conductor film after firing is formed. At this time, the thickness of the conductor pattern after drying is preferably 100 nm or less, particularly preferably 50 nm or less. Next, a plurality of ceramic green sheets on which the above-described conductor pattern is formed are stacked, and are heated and integrated to form a base laminate.
次に、得られた母体積層体を所定の寸法に切断し、焼成後にコンデンサ本体となる生の状態の積層体を得る。次に、この生の積層体を、大気中もしくは窒素雰囲気中にて脱脂した後、水素−窒素の混合ガスの還元雰囲気中にて１０００〜１３００℃の範囲で１〜５時間の条件で焼成する。なお、必要に応じて、焼成温度よりも低い温度（９００〜１１００℃）にて再加熱して酸化処理を行ってもよい。こうして絶縁体である誘電体層３と導体膜である内部電極層４とが交互に積層され一体化されたコンデンサ本体１が得られる。次に、このコンデンサ本体１の対向する端部に、外部電極ペーストを塗布して焼付けを行い外部電極２が形成される。また、この外部電極２の表面には実装性を高めるためにメッキ膜が形成される。 Next, the obtained base material laminate is cut into a predetermined size to obtain a raw material laminate that becomes a capacitor body after firing. Next, this raw laminate is degreased in the air or in a nitrogen atmosphere, and then fired in a reducing atmosphere of a hydrogen-nitrogen mixed gas at a temperature of 1000 to 1300 ° C. for 1 to 5 hours. . If necessary, the oxidation treatment may be performed by reheating at a temperature lower than the firing temperature (900 to 1100 ° C.). In this way, the capacitor body 1 is obtained in which the dielectric layers 3 that are insulators and the internal electrode layers 4 that are conductor films are alternately laminated and integrated. Next, an external electrode paste is applied to the opposite end portions of the capacitor body 1 and baked to form the external electrodes 2. A plating film is formed on the surface of the external electrode 2 in order to improve mountability.
まず、金属源として、純度が９９．１％の硝酸ニッケル（Ｎｉ（ＮＯ３）２）および純度が９９．２％の硝酸銅（Ｃｕ（ＮＯ３）２を準備し、これら硝酸ニッケルおよび硝酸銅を表１に示す割合になるように加え、さらに各種溶媒および添加剤をガラス製容器に投入し、室温（２５℃）にて混合して、ニッケルおよび銅を含有する溶液を調製した。これらの混合割合は、金属源としての硝酸塩１００質量部に対して、添加剤を１０質量部とし、これに第１の溶媒としてイオン交換水を用い、表１に示した第２の溶媒および第３の溶媒の添加量はそれぞれ３００質量部とした。その後、３５℃で、５時間放置して、ニッケルおよび銅を含む溶液を上下２層に分離させて、上部側の溶液中にオレイン酸の前駆体またはマレイン酸の前駆体を形成した。 First, as a metal source, nickel nitrate (Ni (NO 3 ) 2 ) having a purity of 99.1% and copper nitrate (Cu (NO 3 ) 2 having a purity of 99.2% were prepared, and these nickel nitrate and copper nitrate were prepared. Then, various solvents and additives were added to a glass container and mixed at room temperature (25 ° C.) to prepare a solution containing nickel and copper. The mixing ratio is 10 parts by mass of the additive with respect to 100 parts by mass of the nitrate as the metal source, and ion-exchanged water is used as the first solvent for the second solvent and the third solvent shown in Table 1. The amount of the solvent added was 300 parts by mass, and then left at 35 ° C. for 5 hours to separate the solution containing nickel and copper into two upper and lower layers, and the precursor of oleic acid in the upper solution. Or form maleic acid precursor Made.
次に、ガラス製容器の下部側の排出口を開けて容器の下層側の溶媒を排出し、次いで、オレイン酸の前駆体またはマレイン酸の前駆体を含む溶液からデカンテーションにより溶媒を排出してオレイン酸の前駆体またはマレイン酸の前駆体を得た。この後、水洗を行いアルカリ成分などのイオンを除去し、さらにエチルアルコールとヘキサンとの混合溶液を用いて有機成分を除去した。 Next, the lower side outlet of the glass container is opened to discharge the solvent on the lower side of the container, and then the solvent is discharged from the solution containing the oleic acid precursor or the maleic acid precursor by decantation. An oleic acid precursor or maleic acid precursor was obtained. Thereafter, washing with water was performed to remove ions such as alkali components, and organic components were removed using a mixed solution of ethyl alcohol and hexane.
次に、得られたオレイン酸の前駆体またはマレイン酸の前駆体を石英の容器に入れ、これを加熱炉内に置き、Ｎ２−５％Ｈ２の混合ガスを供給して、表１に示す温度に加熱して、前駆体を分解させて超微粒の合金粉末を得た。そして、得られた合金粉末の平均粒径、結晶構造、および異相の割合を求めた。 Next, the obtained precursor of oleic acid or maleic acid was put in a quartz container, and this was placed in a heating furnace, and a mixed gas of N 2 -5% H 2 was supplied. The precursor was decomposed by heating to the indicated temperature to obtain an ultrafine alloy powder. And the average particle diameter of the obtained alloy powder, the crystal structure, and the ratio of the different phase were calculated | required.
得られた合金粉末の平均粒径は、走査型電子顕微鏡を用いて合金粉末の写真を撮り、その写真上で粒子が約３０個入る円を描き、円内および円周にかかった粒子を選択し、各粒子の輪郭を画像処理し、各粒子を円と見立てて円相当径を算出し、その平均値より求めた。 The average particle size of the obtained alloy powder is obtained by taking a photograph of the alloy powder using a scanning electron microscope, drawing a circle containing about 30 particles on the photograph, and selecting particles that fall within and around the circle. Then, the contour of each particle was image-processed, each particle was regarded as a circle, the equivalent circle diameter was calculated, and the average value was obtained.
合金粉末について、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピーク（１１１）のＸ線回折強度に対する、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク（１１１）、ニッケルの酸化物の主ピーク、銅の酸化物の主ピークのうちの最も強いＸ線回折強度の割合は、Ｘ線回折装置（Ｃｕｋα）を用いて、２θ＝３０〜８０°の範囲にて回折し、Ｘ線回折装置から出力される回折強度値を比較して求めた。 The alloy powder is composed of nickel and copper and has an hexagonal close-packed structure (hcp) with respect to the X-ray diffraction intensity of the main peak (111) of the alloy having a cubic close-packed structure (ccp). The ratio of the strongest X-ray diffraction intensity among the main peak (111), the main peak of nickel oxide, and the main peak of copper oxide is 2θ = 30 to 80 using an X-ray diffractometer (Cukα). The diffraction intensity was diffracted in the range of °, and the diffraction intensity values output from the X-ray diffractometer were compared.
次に、上記した合金粉末を用いて導体ペーストを調製し、この導体ペーストを内部電極用のペーストに用いて積層セラミックコンデンサを作製した。まず、上記合金属粉末４０質量％、エチルセルロース５．５質量％とα−テルピネオール９４．５重量％からなるビヒクル５５質量％を３本ロールミルで混練して導体ペーストを作製した。 Next, a conductor paste was prepared using the above-described alloy powder, and a multilayer ceramic capacitor was produced using this conductor paste as an internal electrode paste. First, a conductor paste was prepared by kneading, in a three-roll mill, 40% by mass of the mixed metal powder, 5.5% by mass of ethyl cellulose, and 55% by mass of a vehicle consisting of 94.5% by mass of α-terpineol.
次に、ニッケルの含有量が５０モル％以上の組成の合金粉末およびニッケルの含有量が５０モル％よりも低い組成の合金粉末にそれぞれ適用させる絶縁体を用意した。導体膜にニッケルの含有量が５０モル％以上の組成の合金粉末を用いる場合は、ＢａＴｉＯ３ ９７．５モル％とＣａＺｒＯ３ ２．０モル％とＭｎＯ０．５モル％とからなる主成分１００モル部に対して、Ｙ２Ｏ３を０．５モル部添加した組成とした。ニッケルの含有量が５０モル％よりも低い組成の合金粉末を用いる場合は、上記組成１００質量部に対してホウ珪酸ガラス粉末（ＳｉＯ２：５０モル％，Ａｌ２Ｏ３：５モル％，ＭｇＯ：３０モル％，Ｂ２Ｏ３：１０モル％，ＣａＯ：５モル％）を６０質量部の割合で加えて、それぞれセラミックスラリを調製し、次いで、これらのセラミックスラリをポリエステルの合成樹脂より成る帯状のキャリアフィルム上に、ダイコータ法で成膜し、乾燥させることにより厚みが０．６μｍのセラミックグリーンシートを得た。 Next, an insulator to be applied to an alloy powder having a composition with a nickel content of 50 mol% or more and an alloy powder having a composition with a nickel content lower than 50 mol% was prepared. If the content of nickel conductive film of an alloy powder of the composition of more than 50 mol%, 100 mol of the main component consisting of BaTiO 3 97.5 mol% and CaZrO 3 2.0 mol% and MnO0.5 mol% The composition was 0.5 mol part of Y 2 O 3 added to the part. When using an alloy powder having a nickel content lower than 50 mol%, a borosilicate glass powder (SiO 2 : 50 mol%, Al 2 O 3 : 5 mol%, MgO based on 100 parts by mass of the composition) : 30 mol%, B 2 O 3 : 10 mol%, CaO: 5 mol%) at a ratio of 60 parts by mass, respectively, to prepare a ceramic slurry, and then the ceramic slurry is made of a synthetic resin of polyester. A ceramic green sheet having a thickness of 0.6 μm was obtained by forming a film on a band-shaped carrier film by a die coater method and drying the film.
次に、セラミックグリーンシートをキャリアフィルムから剥離し、縦２００ｍｍ、横２００ｍｍのサイズに打ち抜き、次いで、得られたセラミックグリーンシートの一方主面に、グラビア印刷装置を用いて、上記した導体ペーストを印刷して、印刷厚みで２０〜１５０ｎｍになるように導体パターンを形成した。印刷後の導体パターンの厚みは用いた合金粉末の平均粒径の１０倍以下の厚みを設定した。 Next, the ceramic green sheet is peeled off from the carrier film, punched out to a size of 200 mm in length and 200 mm in width, and then the above-mentioned conductor paste is printed on one main surface of the obtained ceramic green sheet using a gravure printing device. Then, a conductor pattern was formed so that the printed thickness was 20 to 150 nm. The thickness of the conductor pattern after printing was set to a thickness not more than 10 times the average particle diameter of the alloy powder used.
次に、導体パターンが形成されたセラミックグリーンシートを３６０枚積層し、その上下面に導体パターンを印刷していないセラミックグリーンシートをそれぞれ２０枚積層し、プレス機を用いて温度６０℃、圧力１０７Ｐａ、時間１０分の条件で一括積層し、所定の寸法に切断し、生の積層体を得た。 Next, 360 ceramic green sheets on which conductor patterns are formed are stacked, 20 ceramic green sheets on which no conductor patterns are printed are stacked on each of the upper and lower surfaces, and the temperature is 60 ° C. and the pressure is 10 Lamination was performed under conditions of 7 Pa and time 10 minutes, and cut into predetermined dimensions to obtain a raw laminate.
次に、生の積層体を、大気中にて４００℃までの温度範囲で脱脂を行い、還元雰囲気中にて焼成した。導体膜を、ニッケルの含有量が５０モル％以上の組成の合金粉末を含む導体ペーストで形成する場合には１２５０℃で、ニッケルが５０モル％よりも低い組成の合金粉末を含む導体ペーストで形成する場合には９２０℃でそれぞれ２時間焼成してコンデンサ本体を得た。 Next, the raw laminate was degreased in the temperature range up to 400 ° C. and fired in a reducing atmosphere. When the conductor film is formed of a conductor paste containing an alloy powder having a nickel content of 50 mol% or more, the conductor film is formed of a conductor paste containing an alloy powder having a composition of nickel lower than 50 mol% at 1250 ° C. In this case, each capacitor was baked at 920 ° C. for 2 hours to obtain a capacitor body.
このようにして得られたコンデンサ本体の外形寸法は、長さ３．２ｍｍ、幅１．６ｍｍ、厚さ１．０ｍｍであり、内部電極層間に介在する誘電体層の厚みは０．４μｍであった。
また、誘電体層の一層当たりの対向内部電極層の有効面積は２．１ｍｍ２であった。
The external dimensions of the capacitor body thus obtained are 3.2 mm in length, 1.6 mm in width, and 1.0 mm in thickness, and the thickness of the dielectric layer interposed between the internal electrode layers is 0.4 μm. It was.
The effective area of the counter internal electrode layer per layer of the dielectric layer was 2.1 mm 2 .
上述のようにして得られたコンデンサ本体を、各試料１００個ずつ樹脂で固めて研磨し、倍率４００倍の金属顕微鏡観察を行いデラミネーションの有無を検査した。 The capacitor body obtained as described above was solidified with 100 samples of each sample and polished, and observed with a metal microscope at a magnification of 400 times to inspect for the presence of delamination.
なお、作製した合金粉末中のニッケルおよび銅の合計の含有量は、それぞれの標準液を用いてＩＣＰ（Inductively coupled Plasma）発光分光分析により求めた。表１に結果を示した。 The total content of nickel and copper in the produced alloy powder was determined by ICP (Inductively coupled Plasma) emission spectroscopic analysis using each standard solution. Table 1 shows the results.
表１の結果から明らかなように、本発明の製法により得られた合金粉末は、平均粒径が５〜３０ｎｍであり、Ｘ線回折パターンにおいて、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの強い方の回折強度が、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の１０％以下であった。また、このような超微粒の合金粉末を用いて作製した積層セラミックコンデンサでは内部電極層の周囲に段差解消用のセラミックパターンを形成しなくても３６０層の積層体においてもデラミネーションの発生数が１００個中１個以下であった。 As is apparent from the results in Table 1, the alloy powder obtained by the production method of the present invention has an average particle size of 5 to 30 nm, and in the X-ray diffraction pattern, it consists of nickel and copper and has a hexagonal close-packed structure (hcp Of the alloy having a cubic close-packed structure (ccp) composed of nickel and copper, and having the strongest diffraction intensity among the main peak of the alloy having), the main peak of nickel oxide, and the main peak of copper oxide. It was 10% or less of the diffraction intensity of the main peak. In addition, in a multilayer ceramic capacitor manufactured using such an ultrafine alloy powder, the number of occurrences of delamination is increased even in a 360-layer laminate without forming a ceramic pattern for eliminating a step around the internal electrode layer. It was 1 or less out of 100.
特に、本発明の合金粉末の製法により得られたオレイン酸の前駆体およびマレイン酸前駆体を３００〜３５０℃とした試料は、合金粉末の平均粒径が１０ｎｍ以下であり、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの強い方の回折強度が、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の７％以下であり、また、３６０層の積層体においてもデラミネーションの発生が無かった。本発明の製法により作製した合金粉末に含まれるニッケルおよび銅の含有量は、いずれの試料も９９．１％であった。 In particular, a sample in which the precursor of oleic acid and the maleic acid precursor obtained by the method for producing the alloy powder of the present invention is 300 to 350 ° C. has an average particle diameter of the alloy powder of 10 nm or less, and is obtained from nickel and copper. The strongest diffraction intensity of the main peak of the alloy having the hexagonal close-packed structure (hcp), the main peak of the nickel oxide, and the main peak of the copper oxide is a cubic close-packed structure consisting of nickel and copper. It was 7% or less of the diffraction intensity of the main peak of the alloy having (ccp), and no delamination occurred even in the 360-layer laminate. The content of nickel and copper contained in the alloy powder produced by the production method of the present invention was 99.1% for all samples.
これに対して、オレイン酸の前駆体およびマレイン酸の前駆体を２００℃で加熱したものは前駆体の残留があり、また、２３０℃の加熱においても、ニッケルと銅とからなり六方最密構造（ｈｃｐ）を有する合金の主ピーク、ニッケルの酸化物の主ピークおよび銅の酸化物の主ピークのうちの強い方の回折強度が、ニッケルと銅とからなり立方最密構造（ｃｃｐ）を有する合金の主ピークの回折強度の１７％以上であった。また、加熱の温度を４００℃よりも高くした場合には合金粉末の平均粒径が３０ｎｍを遙かに越えるものとなり、評価したコンデンサ本体においてデラミネーションの発生割合が１００個中１０個もあった。なお、試料Ｎｏ．３の条件にて合金粉末を作製する際に、中間の生成物であるオレイン酸の前駆体の水洗を行わずに合金粉末を調製し、この合金粉末を用いて試料Ｎｏ．３の合金粉末と同様の条件でコンデンサ本体を作製した試料ではデラミネーションの発生割合が１００個中１５個であった。この合金粉末におけるニッケルおよび銅の含有量は９８．８質量％であった。 On the other hand, when the precursor of oleic acid and the precursor of maleic acid are heated at 200 ° C., the precursor remains, and even when heated at 230 ° C., it consists of nickel and copper and has a hexagonal close-packed structure. The higher diffraction intensity of the main peak of the alloy having (hcp), the main peak of nickel oxide, and the main peak of copper oxide is made of nickel and copper and has a cubic close-packed structure (ccp). It was 17% or more of the diffraction intensity of the main peak of the alloy. In addition, when the heating temperature was higher than 400 ° C., the average particle size of the alloy powder was much larger than 30 nm, and the evaluated capacitor body had a delamination generation rate of 10 out of 100. . Sample No. When the alloy powder was produced under the conditions of No. 3, an alloy powder was prepared without washing the precursor of oleic acid, which is an intermediate product, with Sample No. In the sample in which the capacitor main body was produced under the same conditions as the alloy powder of No. 3, the occurrence rate of delamination was 15 out of 100. The alloy powder contained 98.8% by mass of nickel and copper.
１ コンデンサ本体
２ 外部電極
３ 誘電体層（絶縁体）
４ 内部電極層（導体膜）
1 Capacitor body 2 External electrode 3 Dielectric layer (insulator)
4 Internal electrode layer (conductor film)
Claims (6)
（ｂ）該溶液から、前記ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を得る工程と、
（ｃ）前記ニッケルおよび銅を含むオレイン酸の前駆体またはマレイン酸の前駆体を、還元雰囲気中にて、２５０〜４００℃の温度で加熱する工程と、
を具備することを特徴とするニッケル−銅合金粉末の製法。 (A) A step of preparing a solution containing nickel and copper by dissolving nickel nitrate and copper nitrate and sodium oleate or sodium maleate in a mixed solvent of water and a solvent having a polarity lower than that of water. When,
(B) obtaining a precursor of oleic acid or maleic acid containing nickel and copper from the solution;
(C) heating the precursor of oleic acid or maleic acid containing nickel and copper at a temperature of 250 to 400 ° C. in a reducing atmosphere;
A process for producing a nickel-copper alloy powder, comprising:
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| PCT/JP2009/063389 WO2010035573A1 (en) | 2008-09-26 | 2009-07-28 | Nickel-copper alloy powder, process for producing the nickel-copper alloy powder, conductive paste, and electronic component |
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| JP2015141860A (en) * | 2014-01-30 | 2015-08-03 | 株式会社豊田中央研究所 | Joint material and semiconductor device using the same |
| JP2016145422A (en) * | 2012-01-17 | 2016-08-12 | Ｄｏｗａエレクトロニクス株式会社 | Silver coated copper alloy powder and manufacturing method therefor |
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| WO2015060119A1 (en) * | 2013-10-21 | 2015-04-30 | 東洋紡株式会社 | Nickel-copper alloy thin layer laminate film |
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| JPH0320907A (en) * | 1989-06-16 | 1991-01-29 | Kawasaki Steel Corp | Conductive paste |
| JPH0711367A (en) * | 1993-06-24 | 1995-01-13 | Sumitomo Electric Ind Ltd | Co alloy wire rod and its production |
| JPH10183207A (en) * | 1996-12-19 | 1998-07-14 | Tomoe Seisakusho:Kk | Ultrafine grain and production thereof |
| JP2006169559A (en) * | 2004-12-14 | 2006-06-29 | Sumitomo Metal Mining Co Ltd | Copper alloy fine-particle and method for producing the same |
| JP2008197852A (en) * | 2007-02-10 | 2008-08-28 | Phifit Kk | Analysis device and analysis system for structure development of workpiece in plastic working, and recording medium |
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| JPH0320907A (en) * | 1989-06-16 | 1991-01-29 | Kawasaki Steel Corp | Conductive paste |
| JPH0711367A (en) * | 1993-06-24 | 1995-01-13 | Sumitomo Electric Ind Ltd | Co alloy wire rod and its production |
| JPH10183207A (en) * | 1996-12-19 | 1998-07-14 | Tomoe Seisakusho:Kk | Ultrafine grain and production thereof |
| JP2006169559A (en) * | 2004-12-14 | 2006-06-29 | Sumitomo Metal Mining Co Ltd | Copper alloy fine-particle and method for producing the same |
| JP2008197852A (en) * | 2007-02-10 | 2008-08-28 | Phifit Kk | Analysis device and analysis system for structure development of workpiece in plastic working, and recording medium |
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| JP2016145422A (en) * | 2012-01-17 | 2016-08-12 | Ｄｏｗａエレクトロニクス株式会社 | Silver coated copper alloy powder and manufacturing method therefor |
| JP2017150086A (en) * | 2012-01-17 | 2017-08-31 | Ｄｏｗａエレクトロニクス株式会社 | Silver coated copper alloy powder and manufacturing method therefor |
| JP2015141860A (en) * | 2014-01-30 | 2015-08-03 | 株式会社豊田中央研究所 | Joint material and semiconductor device using the same |
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