JP6389628B2 - Copper powder, method for producing the same, and conductive composition containing the same - Google Patents
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims description 185
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000000203 mixture Substances 0.000 title claims description 15
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- 229910052802 copper Inorganic materials 0.000 claims description 89
- 239000010949 copper Substances 0.000 claims description 89
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(I) oxide Inorganic materials [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 claims description 23
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 claims description 23
- 229940112669 cuprous oxide Drugs 0.000 claims description 23
- 239000011164 primary particle Substances 0.000 claims description 23
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- 238000010296 bead milling Methods 0.000 claims description 3
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- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000004220 aggregation Methods 0.000 description 3
- 150000002894 organic compounds Chemical class 0.000 description 3
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- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 2
- 239000001856 Ethyl cellulose Substances 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 2
- 229920001249 ethyl cellulose Polymers 0.000 description 2
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- UODXCYZDMHPIJE-UHFFFAOYSA-N menthanol Chemical compound CC1CCC(C(C)(C)O)CC1 UODXCYZDMHPIJE-UHFFFAOYSA-N 0.000 description 2
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- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 241000282341 Mustela putorius furo Species 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
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- 229920003064 carboxyethyl cellulose Polymers 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 229910000365 copper sulfate Inorganic materials 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
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- YWXYYJSYQOXTPL-SLPGGIOYSA-N isosorbide mononitrate Chemical compound [O-][N+](=O)O[C@@H]1CO[C@@H]2[C@@H](O)CO[C@@H]21 YWXYYJSYQOXTPL-SLPGGIOYSA-N 0.000 description 1
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- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
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Description
本発明は銅粉に関する。また本発明は、銅粉の製造方法、及び銅粉を含む導電性組成物に関する。 The present invention relates to copper powder. Moreover, this invention relates to the manufacturing method of copper powder, and the electroconductive composition containing copper powder.
銅粉を構成する個々の銅粒子の形状には、一般に球形状や扁平形状、不定形状などがあり、銅粉の具体的な用途に応じて適切な形状を有するものが選択されている。そのような銅粒子の形状の一つとして、立方体形状のものが提案されている（特許文献１参照）。同文献に記載の技術は、立方体形状の銅粒子を用いることで、該銅粒子から形成される配線における粒子間に空隙が発生することを防止して電気抵抗を低減させたり、配線の高さを高くしたりすることを目的としている。 In general, the shape of each copper particle constituting the copper powder includes a spherical shape, a flat shape, an indefinite shape, and the like, and those having an appropriate shape are selected according to the specific use of the copper powder. As one of the shapes of such copper particles, a cubic shape has been proposed (see Patent Document 1). The technology described in the same document uses cubic copper particles to prevent voids from being generated between the particles in the wiring formed from the copper particles, thereby reducing electrical resistance or increasing the height of the wiring. The purpose is to raise.
また、銅そのものではないが、亜酸化銅に関し、本出願人は先に、立方体形状を有する亜酸化銅粒子から構成される亜酸化銅粉を提案した（特許文献２参照）。 Moreover, although it is not copper itself, regarding the cuprous oxide, this applicant previously proposed the cuprous oxide powder comprised from the cuprous oxide particle which has a cube shape (refer patent document 2).
特許文献１に記載の立方体形状の銅粉は、それを構成する粒子の大きさが５ｎｍ以上５０ｎｍ以下という微小なナノサイズのものなので、そのことに起因して粒子どうしの凝集が起こりやすい。その結果、立方体形状の粒子を採用しているにもかかわらず、粒子間に空隙が発生しやすく、導電体の表面を平滑にすることが容易でない。また導電体の充填率を高くすることが困難となり、抵抗率が高くなる。凝集を抑制する目的で、有機化合物からなる表面処理剤を粒子の表面に施すことが考えられるが、その場合には、導電体を製造するときに加わる熱によって、表面処理剤の分解ガスが発生し、導電体にブリスターが発生しやすくなる。そのことによっても、導電体の平滑性が損なわれやすく、また充填率も低くなるため低抵抗化が困難となる。 The cube-shaped copper powder described in Patent Document 1 is a fine nano-sized particle having a particle size of 5 nm or more and 50 nm or less. Therefore, aggregation of particles tends to occur. As a result, although cubic particles are employed, voids are likely to be generated between the particles, and it is not easy to smooth the surface of the conductor. Moreover, it becomes difficult to increase the filling rate of the conductor, and the resistivity increases. In order to suppress agglomeration, it is conceivable to apply a surface treatment agent made of an organic compound to the surface of the particles. In this case, decomposition gas of the surface treatment agent is generated by the heat applied when the conductor is produced. In addition, blisters are likely to occur in the conductor. This also makes it difficult to reduce the resistance because the smoothness of the conductor is liable to be impaired and the filling rate is lowered.
特許文献２には、立方体形状の亜酸化銅粒子が記載されているにとどまり、該亜酸化銅粒子を用いてどのような方法で立方体形状の銅粒子を製造するかについては言及されていない。 Patent Document 2 only describes cube-shaped cuprous oxide particles, and does not mention how to produce the cube-shaped copper particles by using the cuprous oxide particles.
したがって本発明の課題は、表面の平滑性が高い導電体を形成し得る銅粉その製造方法、及びそれを含む導電性組成物を提供することにある。 Therefore, the subject of this invention is providing the copper powder which can form the conductor with high surface smoothness, its manufacturing method, and an electroconductive composition containing the same.
本発明は、直方体形状を有する銅粒子から構成され、一次粒子の平均粒径が１μｍ以上１５μｍ以下である銅粉を提供することにより前記の課題を解決したものである。 This invention solves the said subject by providing the copper powder which is comprised from the copper particle which has a rectangular parallelepiped shape, and whose average particle diameter of a primary particle is 1 micrometer or more and 15 micrometers or less.
また本発明は、前記の銅粉の好適な製造方法として、一次粒子の平均粒径が１．０μｍ以上１５．０μｍ以下である直方体形状を有する亜酸化銅粒子を、−８００ｍＶ以下にすることによって湿式還元する工程を有する銅粉の製造方法を提供するものである。 Moreover, this invention makes the cuprous oxide particle which has a rectangular parallelepiped shape whose average particle diameter of a primary particle is 1.0 micrometer or more and 15.0 micrometers or less as a suitable manufacturing method of the said copper powder by making it -800 mV or less. The present invention provides a method for producing a copper powder having a wet reduction process.
また本発明は、前記の銅粉の別の好適な製造方法として、体積累積粒径一次粒子の平均粒径が１．０μｍ以上１５．０μｍ以下である球形状を有する銅粒子を含むスラリーを、ビーズミル処理する工程を有する銅粉の製造方法を提供するものである。 Further, the present invention provides a slurry containing copper particles having a spherical shape in which the average particle size of primary particles having a volume cumulative particle size of 1.0 μm or more and 15.0 μm or less, as another preferred method for producing the copper powder, The present invention provides a method for producing copper powder having a step of bead milling.
更に本発明は、前記の銅粉と、樹脂と、有機溶媒とを含む導電性組成物を提供するものである。 Furthermore, this invention provides the electroconductive composition containing the said copper powder, resin, and an organic solvent.
本発明の銅粉を用いて導電体を製造すると、該導電体はその表面が平滑で、かつ充填密度が高くなり抵抗率が低いものとなる。 When a conductor is produced using the copper powder of the present invention, the conductor has a smooth surface, a high packing density, and a low resistivity.
以下本発明を、その好ましい実施形態に基づき説明する。本発明の銅粉は、それを構成する銅粒子の形状に特徴の一つを有する。具体的には銅粒子は直方体形状を有する。直方体形状を有する銅粒子は、六つの平面を有する六面体であり、各平面は略矩形をしている。略矩形とは、矩形を構成する四辺のうち、互いに交差する二辺のなす角度が９０度である場合、及び９０度に対してプラスマイナス２０度の範囲内である場合の双方を包含する。 Hereinafter, the present invention will be described based on preferred embodiments thereof. The copper powder of this invention has one of the characteristics in the shape of the copper particle which comprises it. Specifically, the copper particles have a rectangular parallelepiped shape. The copper particles having a rectangular parallelepiped shape are hexahedrons having six planes, and each plane has a substantially rectangular shape. The “substantially rectangular” includes both the case where the angle formed by two sides intersecting each other among the four sides constituting the rectangle is 90 degrees and the case where the angle is within a range of plus or minus 20 degrees with respect to 90 degrees.
直方体形状を有する銅粒子が有する六つの平面は、隣り合う平面とのなす角度が概ね９０度になっている。概ね９０度とは、隣り合う平面とのなす角度が９０度である場合、及び９０度に対してプラスマイナス２０度の範囲内である場合の双方を包含する。 The six planes of the copper particles having a rectangular parallelepiped shape have an angle of 90 degrees with an adjacent plane. About 90 degrees includes both the case where the angle between adjacent planes is 90 degrees and the case where the angle is within the range of plus or minus 20 degrees with respect to 90 degrees.
直方体形状を有する銅粒子は、略矩形状である各面を観察したときに、図１に示すとおり、各面を画定する四辺のうち、互いに交差する二辺ａ，ｂの長さの比率であるａ／ｂの値（以下「アスペクト比」とも言う。）が１以上５以下であることが好ましく、１以上３以下であることが更に好ましく、１以上２以下であることが一層好ましい。この関係は、六つの面のうちの少なくとも一つの面で成立していることが好ましく、最も好ましくは六つの面のすべてで成立している。 The copper particles having a rectangular parallelepiped shape have a ratio of the lengths of two sides a and b intersecting each other among the four sides defining each surface, as shown in FIG. The value of a / b (hereinafter also referred to as “aspect ratio”) is preferably 1 or more, 5 or less, more preferably 1 or more and 3 or less, and even more preferably 1 or more and 2 or less. This relationship is preferably established on at least one of the six surfaces, and most preferably on all six surfaces.
また、直方体形状を有する銅粒子は、略矩形状である各面を観察したときに、図１に示すとおり最大長ＬＭと長軸長ＬＡとの比率であるＬＭ／ＬＡの値が、１．０５以上１．４１以下であることが好ましく、１．１０以上１．４１以下であることが更に好ましく、１．１２以上１．４１以下であることが一層好ましい。この関係は、六つの面のうちの少なくとも一つの面で成立していることが好ましく、最も好ましくは六つの面のすべてで成立している。 Further, the copper particles having a rectangular shape, when observed the surfaces is substantially rectangular, the value of L M / L A is the ratio of the maximum length L M and the major axis length L A as shown in FIG. 1 Is preferably 1.05 or more and 1.41 or less, more preferably 1.10 or more and 1.41 or less, and still more preferably 1.12 or more and 1.41 or less. This relationship is preferably established on at least one of the six surfaces, and most preferably on all six surfaces.
直方体形状を有する銅粒子は、最も好ましくは略立方体形状を有している。略立方体形状とは、六つの平面のいずれもが略同寸法の略正方形をしており、隣り合う平面とのなす角度が概ね９０度になっている立体形状である。特に、図１に示すとおり、各面を画定する四辺のうち、互いに交差する二辺ａ，ｂの長さの比率であるａ／ｂの値が１以上５以下であることが好ましい。また、最大長ＬＭと長軸長ＬＡとの比率であるＬＭ／ＬＡの値が、１．０２以上１．４１以下であることが好ましい。 The copper particles having a rectangular parallelepiped shape most preferably have a substantially cubic shape. The substantially cubic shape is a three-dimensional shape in which each of the six planes has a substantially square shape with substantially the same size, and an angle between adjacent planes is approximately 90 degrees. In particular, as shown in FIG. 1, it is preferable that the value of a / b, which is the ratio of the lengths of two sides a and b intersecting each other, among the four sides defining each surface is 1 or more and 5 or less. The value of the ratio of the maximum length L M and the major axis length L A L M / L A is preferably 1.02 or more 1.41 or less.
上述した直方体形状を有する銅粒子の集合体から構成される本発明の銅粉は、該銅粒子の形状に起因して、粒子が規則正しく積み上げられるので、該銅粉から形成される導電体の表面が平滑なものとなるという有利な効果を奏する。特に、銅粒子が立方体形状である場合、粒子の積み上げが一層規則正しくなるので、導電体の表面が一層平滑になる。また、その形状に起因して、及び表面炭素量が少ないことに起因して、導電体の充填密度を高くすることができ、それによって導電体は低抵抗なものとなる。導電体の表面が平滑でかつ充填密度が高いことは、該導電体と電気的な導通を行うための他の導電体との電気的な接触の信頼性が高まる点や、電気抵抗の上昇が抑制される点、及び回路表面粗さに起因する高周波伝送ノイズが抑制される点等から有利である。 The copper powder of the present invention composed of an aggregate of copper particles having the above-mentioned rectangular parallelepiped shape is such that the particles are regularly stacked due to the shape of the copper particles, so the surface of the conductor formed from the copper powder Has an advantageous effect of smoothing. In particular, when the copper particles have a cubic shape, the accumulation of particles becomes more regular, and the surface of the conductor becomes smoother. Further, due to the shape and due to the small amount of surface carbon, the filling density of the conductor can be increased, and thereby the conductor has a low resistance. The surface of the conductor is smooth and the packing density is high, which means that the reliability of electrical contact with other conductors for electrical conduction with the conductor is increased, and that the electrical resistance is increased. This is advantageous because it is suppressed and high-frequency transmission noise due to circuit surface roughness is suppressed.
本発明の銅粉は、上述した直方体形状を有する銅粒子の集合体から構成され、好ましくは立方体形状を有する銅粒子の集合体から構成される。また、直方体形状を有する銅粒子及び立方体形状を有する銅粒子の集合体から構成されていてもよい。更に、本発明の銅粉においては、上述した本発明の効果を損なわない範囲において、直方体形状及び立方体形状以外の形状を有する銅粒子を含むことが許容される。直方体形状及び立方体形状以外の形状とは、例えば球形状、鱗片形状及び樹状などが挙げられる。 The copper powder of this invention is comprised from the aggregate | assembly of the copper particle which has a rectangular parallelepiped shape mentioned above, Preferably it is comprised from the aggregate | assembly of the copper particle which has a cube shape. Moreover, you may be comprised from the aggregate | assembly of the copper particle which has a rectangular parallelepiped shape, and the copper particle which has a cube shape. Furthermore, the copper powder of the present invention is allowed to contain copper particles having shapes other than a rectangular parallelepiped shape and a cubic shape within a range not impairing the above-described effects of the present invention. Examples of shapes other than the rectangular parallelepiped shape and the cubic shape include a spherical shape, a scale shape, and a tree shape.
本発明の銅粉を構成する銅粒子は、それが直方体形状及び立方体形状のいずれの場合であっても、本発明の効果を損なわない範囲において、八箇所の角部のうちのいずれかが欠けていてもよい。例えば、銅粒子が立方体形状である場合、正方形の見かけの一辺長（つまり、角欠け部が存在しないとみなしたときの一辺長さ）に対して、角欠け部の長さが５０％以下、特に３０％以下であれば、本発明の効果は十分に奏される。 The copper particles constituting the copper powder of the present invention are missing any of the eight corners as long as the effect of the present invention is not impaired, regardless of whether the copper particles are rectangular or cubic. It may be. For example, when the copper particles have a cubic shape, the length of the corner chipped portion is 50% or less with respect to the apparent one side length of the square (that is, the one side length when the corner chipped portion is regarded as not present), In particular, if it is 30% or less, the effect of the present invention is sufficiently exhibited.
また本発明の銅粉を構成する銅粒子は、銅粒子の集合体に占める直方体形状（立方体形状を含む）の粒子の割合が、好ましくは７０個数％以上１００個数％以下、より好ましくは７５個数％以上１００個数％以下であることで、導電体表面との平滑性を発揮することができる。この場合、銅粒子の集合体を日本電子（株）製ＪＳＭ−６３３０Ｆを使った電子顕微鏡写真から、ＭＡＣ−Ｖｉｅｗ（Ｍｏｕｎｔｅｃｈ Ｃｏ．， Ｌｔｄ．製）を使って画像解析することで。粒子個々の形状及び集合体中での存在割合を求めることができる。 Further, the copper particles constituting the copper powder of the present invention preferably have a ratio of a rectangular parallelepiped shape (including a cubic shape) in the aggregate of copper particles, preferably 70 number% to 100 number%, more preferably 75 numbers. % Or more and 100% by number or less can exhibit smoothness with the conductor surface. In this case, by analyzing the image of the aggregate of copper particles from an electron micrograph using JSM-6330F manufactured by JEOL Ltd. using MAC-View (Mounttech Co., Ltd.). The shape of each particle and the existence ratio in the aggregate can be obtained.
本発明の銅粉は、一次粒子の平均粒径が１μｍ以上１５μｍ以下である。この範囲の値を有する銅粉は、これを構成する銅粒子の表面に、有機化合物からなる表面処理剤による表面処理を行わなくても、粒子どうしの凝集を抑制することができる。表面処理を不要にするという観点からは、本発明の銅粉は、前記の値が、１μｍ以上１０μｍ以下であることが更に好ましい。 The copper powder of the present invention has an average primary particle size of 1 μm or more and 15 μm or less. The copper powder having a value within this range can suppress aggregation of particles without performing surface treatment with a surface treatment agent comprising an organic compound on the surface of the copper particles constituting the copper powder. From the viewpoint of eliminating the need for surface treatment, the copper powder of the present invention more preferably has a value of 1 μm or more and 10 μm or less.
一次粒子の平均粒径の値は、走査型電子顕微鏡（日本電子（株）製ＪＳＭ−６３３０Ｆ）を用い、倍率１０，０００倍又は３０，０００倍で、銅粉を観察し、視野中の粒子２００個について水平方向フェレ径を測定し、測定した値から、球に換算した体積平均粒径を算出して求められる。 The average particle size of the primary particles was determined by observing copper powder at a magnification of 10,000 or 30,000 times using a scanning electron microscope (JSM-6330F manufactured by JEOL Ltd.). The horizontal ferret diameter is measured for 200 pieces, and the volume average particle diameter converted to a sphere is calculated from the measured value.
上述のとおり、本発明の銅粉は、有機化合物からなる表面処理剤による表面処理を行わなくても、粒子どうしの凝集を抑制することができるものである。このことに起因して、本発明の銅粉は、表面処理剤に由来する炭素の含有量の少ないものである。具体的には、本発明の銅粉における炭素の含有量は、好ましくは０．２質量％以下という少量であり、更に好ましくは０．１５質量％以下、一層好ましくは０．１質量％以下という少量である。本発明の銅粉における炭素の含有量は、例えば炭素・硫黄分析装置（堀場製作所製、ＥＭＩＡ−３２０Ｖ）を用いて測定することができる。 As described above, the copper powder of the present invention can suppress aggregation of particles without performing a surface treatment with a surface treatment agent comprising an organic compound. Due to this, the copper powder of the present invention has a low carbon content derived from the surface treatment agent. Specifically, the carbon content in the copper powder of the present invention is preferably a small amount of 0.2% by mass or less, more preferably 0.15% by mass or less, and even more preferably 0.1% by mass or less. A small amount. The carbon content in the copper powder of the present invention can be measured, for example, using a carbon / sulfur analyzer (manufactured by Horiba, Ltd., EMIA-320V).
また本発明の銅粉においては、上述した炭素の含有量とＢＥＴ比表面積の比である〔炭素の含有量（質量％）／ＢＥＴ比表面積（ｍ２／ｇ）〕の値が、好ましくは１．０以下という少量であり、更に好ましくは０．６以下、一層好ましくは０．４以下という少量である。この比が、このような小さな値であることは、銅粉焼成時のガス発生量が少なくなるという点から有利である。 In the copper powder of the present invention, the value of [carbon content (mass%) / BET specific surface area (m 2 / g)], which is the ratio of the above-described carbon content and BET specific surface area, is preferably 1 The amount is as small as 0.0 or less, more preferably 0.6 or less, and still more preferably 0.4 or less. It is advantageous that this ratio is such a small value because the amount of gas generated during copper powder firing is reduced.
本発明の銅粉は、これを構成する銅粒子の表面を観察したときに、該表面が、微細な凹凸形状となっていることが好ましい。つまり銅粒子は、これをその全体形状が把握できる程度の拡大倍率で顕微鏡観察を行うと、該銅粒子の各面の表面は平坦であるものの、各面を拡大観察すると、微細な凹凸形状が観察されるものである。微細な凹凸形状は、略矩形ないし略正方形を有する平坦面の全域にわたっていることが好ましい。また微細な凹凸形状は、直方体形状ないし立方体形状を有する銅粒子の六つの面のうち、少なくとも一面において観察されることが好ましく、六つの面のすべてにおいて観察されることが最も好ましい。粒子の表面が微細な凹凸形状となっていることによって、本発明の銅粉は、これを構成する銅粒子どうし、あるいは銅粒子−基板間での摩擦力が高まることに起因して接着力が向上することで、低抵抗率や高密着性に優れた特性を示すという有利な効果を奏する。 When the copper powder of this invention observes the surface of the copper particle which comprises this, it is preferable that this surface is a fine uneven | corrugated shape. In other words, when the copper particles are observed with a microscope at an enlargement magnification at which the overall shape can be grasped, the surface of each surface of the copper particles is flat. What is observed. It is preferable that the fine concavo-convex shape extends over the entire flat surface having a substantially rectangular or substantially square shape. The fine uneven shape is preferably observed on at least one of the six surfaces of the copper particles having a rectangular parallelepiped shape or a cubic shape, and is most preferably observed on all six surfaces. Because the surface of the particles has a fine uneven shape, the copper powder of the present invention has an adhesive force due to an increase in frictional force between the copper particles constituting the particles or between the copper particles and the substrate. By improving, there is an advantageous effect of exhibiting characteristics excellent in low resistivity and high adhesion.
また本発明の銅粉は、これを構成する銅粒子が多孔質体であることも好ましい。銅粒子が多孔質体である場合、該多孔質体に形成されている孔は、オープンセル型のものであってもよく、あるいはクローズドセル型のものであってもよい。好ましくは、孔はオープンセル型のものである。銅粒子が多孔質体であると、本発明の銅粉は、微小粒径でないにもかかわらず、その焼結開始温度が低くなるという点で有利なものとなる。 Moreover, it is preferable that the copper particle which comprises this copper powder of this invention is a porous body. When the copper particles are a porous body, the pores formed in the porous body may be an open cell type or a closed cell type. Preferably, the holes are of the open cell type. When the copper particle is a porous body, the copper powder of the present invention is advantageous in that the sintering start temperature is lowered although the particle size is not small.
上述の効果を一層顕著なものとする観点から、多孔質体からなる銅粒子から構成される本発明の銅粉は、そのＢＥＴ比表面積が０．１ｍ２／ｇ以上１０ｍ２／ｇ以下であることが好ましく、０．１５ｍ２／ｇ以上９．０ｍ２／ｇ以下であることが更に好ましく、０．２ｍ２／ｇ以上８．０ｍ２／ｇ以下であることが一層好ましい。ＢＥＴ比表面積は、例えば、本発明の銅粉２．０ｇを、７５℃で１０分間の脱気処理を行った後、モノソーブ（カンタクロム社製）を用いてＢＥＴ１点法で測定することができる。 From the viewpoint of making the above-mentioned effect more remarkable, the copper powder of the present invention composed of copper particles made of a porous body has a BET specific surface area of 0.1 m 2 / g or more and 10 m 2 / g or less. It is preferably 0.15 m 2 / g or more and 9.0 m 2 / g or less, and more preferably 0.2 m 2 / g or more and 8.0 m 2 / g or less. The BET specific surface area can be measured by, for example, BET one-point method using a monosorb (manufactured by Kantachrome Co., Ltd.) after degassing treatment of 2.0 g of the copper powder of the present invention at 75 ° C. for 10 minutes.
本発明の銅粉においては、上述したＢＥＴ比表面積と、銅粒子の一次粒子径の平均粒径との比である〔ＢＥＴ比表面積（ｍ２／ｇ）／一次粒子径の平均粒径（μｍ）〕の値が、好ましくは０．０１以上１０．０以下、更に好ましくは０．０１５以上５．０以下、一層好ましくは０．０２以上３．０以下であることも、上述の効果を更に一層顕著なものとする観点から好ましい。 In the copper powder of the present invention, the ratio of the BET specific surface area and the average particle diameter of the primary particle diameter of the copper particles [BET specific surface area (m 2 / g) / average particle diameter of primary particle diameter (μm )] Is preferably not less than 0.01 and not more than 10.0, more preferably not less than 0.015 and not more than 5.0, and still more preferably not less than 0.02 and not more than 3.0. It is preferable from the viewpoint of making it more remarkable.
次に、本発明の銅粉の好適な製造方法について説明する。本発明の銅粉は、（イ）湿式法、及び（ロ）乾式法のいずれかの方法で製造することができる。以下、これらの方法について説明する。 Next, the suitable manufacturing method of the copper powder of this invention is demonstrated. The copper powder of the present invention can be produced by any one of (a) a wet method and (b) a dry method. Hereinafter, these methods will be described.
（イ）の湿式法においては、直方体形状、好ましくは立方体形状を有する亜酸化銅粒子を湿式還元する操作を行う。直方体形状ないし立方体形状を有する亜酸化銅粒子の製造方法は公知であり、例えば本出願人の先の出願に係る特開２００５−２５５４４６号公報に記載されている。具体的には、硫酸銅などの銅塩含有溶液にアルカリ溶液を加え、濃度（酸化銅（ＣｕＯ）換算）０．３モル／Ｌ以上１．８モル／Ｌ以下のスラリーを調製し、その後、該スラリーに還元糖を添加時間７０分〜４８０分の条件で添加し撹拌することで製造される。還元糖としてはグルコースを用いることが好ましい。グルコースは好適には水溶液の形態で用いる。この場合、グルコース濃度が０．１モル／Ｌ以上５モル／Ｌ以下であり、グルコース添加量はスラリー中の銅元素１モルに対してグルコース０．２モル以上２モル以下であることが好ましい。アルカリ溶液としては、例えば水酸化ナトリウム溶液、水酸化カリウム溶液、水酸化リチウム溶液、炭酸カリウム溶液又はこれらの混合溶液を用いることが好ましい。 In the wet method (i), an operation of wet-reducing cuprous oxide particles having a rectangular parallelepiped shape, preferably a cubic shape, is performed. A method for producing cuprous oxide particles having a rectangular parallelepiped shape or a cubic shape is known, and is described in, for example, Japanese Patent Application Laid-Open No. 2005-255446 related to the previous application of the present applicant. Specifically, an alkali solution is added to a copper salt-containing solution such as copper sulfate to prepare a slurry having a concentration (in terms of copper oxide (CuO)) of 0.3 mol / L to 1.8 mol / L, It is produced by adding reducing sugar to the slurry under conditions of an addition time of 70 minutes to 480 minutes and stirring. Glucose is preferably used as the reducing sugar. Glucose is preferably used in the form of an aqueous solution. In this case, the glucose concentration is preferably 0.1 mol / L or more and 5 mol / L or less, and the amount of glucose added is preferably 0.2 mol or more and 2 mol or less of glucose with respect to 1 mol of copper element in the slurry. As the alkaline solution, for example, a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, a potassium carbonate solution, or a mixed solution thereof is preferably used.
このようにして得られた亜酸化銅粒子を水に分散させてスラリーを得る。スラリーは必要に応じて加温してもよい。加温する場合、スラリー温度を２５℃以上８０℃以下にすることが好ましい。このスラリーと還元剤とを混合して亜酸化銅粒子の湿式還元を行う。本発明者の検討の結果、還元剤として系中の還元電位を−８００ｍＶ以下にできるものを用いると、原料である亜酸化銅粒子の形状及び寸法を維持したまま、銅粒子を生成させ得ることが判明した。この観点から、本発明においては還元剤として水素化ホウ素ナトリウムを用いることが有利である。これに対して、後述する比較例１から明らかなとおり、還元剤として、系中の還元電位を−８００ｍＶ以下にできないもの、例えばヒドラジンは還元電位が−３００ｍＶと高いため、原料が直方体形状ないし立方体形状を有する亜酸化銅粒子であっても、直方体形状ないし立方体形状を有する銅粒子を得ることはできない。 The cuprous oxide particles thus obtained are dispersed in water to obtain a slurry. The slurry may be heated as necessary. When heating, it is preferable to make slurry temperature into 25 degreeC or more and 80 degrees C or less. This slurry and a reducing agent are mixed to perform wet reduction of the cuprous oxide particles. As a result of the study by the present inventor, when a reducing agent capable of reducing the reduction potential in the system to −800 mV or less is used, copper particles can be generated while maintaining the shape and dimensions of the cuprous oxide particles as a raw material. There was found. From this point of view, it is advantageous to use sodium borohydride as a reducing agent in the present invention. On the other hand, as will be apparent from Comparative Example 1 described later, as the reducing agent, a reduction potential in the system that cannot be reduced to −800 mV or less, for example, hydrazine has a high reduction potential of −300 mV, so Even with cuprous oxide particles having a shape, copper particles having a rectangular parallelepiped shape or a cubic shape cannot be obtained.
上述のとおり、直方体形状ないし立方体形状を有する亜酸化銅粒子の湿式還元を、系中の還元電位が−８００ｍＶ以下にすることができる、例えば水素化ホウ素ナトリウムによって行うことで、原料である亜酸化銅粒子の形状及び寸法を維持したまま、銅粒子が生成する。したがって、目的とする銅粒子の粒径の制御のためには、原料である亜酸化銅粒子として適切な粒径を有するものを使用すればよい。例えば一次粒子の平均粒径が好ましくは１．０μｍ以上１５．０μｍ以下、更に好ましくは１．０μｍ以上１０．０μｍ以下である直方体形状ないし立方体形状を有する亜酸化銅粒子を用いる。 As described above, by performing wet reduction of cuprous oxide particles having a rectangular parallelepiped shape or a cubic shape with a reduction potential in the system of −800 mV or less, for example, by using sodium borohydride, suboxide which is a raw material Copper particles are produced while maintaining the shape and dimensions of the copper particles. Therefore, what is necessary is just to use what has a suitable particle size as a cuprous oxide particle which is a raw material in order to control the particle size of the target copper particle. For example, cuprous oxide particles having a rectangular parallelepiped shape or a cubic shape with an average primary particle size of preferably 1.0 μm or more and 15.0 μm or less, and more preferably 1.0 μm or more and 10.0 μm or less are used.
上述した方法で製造された亜酸化銅粒子は中実のものであり、多孔質体ではない。しかし、驚くべきことに、この亜酸化銅粒子を、系中の還元電位が−８００ｍＶ以下にすることができる水素化ホウ素ナトリウムによって湿式還元すると、形状及び寸法を維持したまま、表面に微細な凹凸形状を有し、また多孔質体である銅粒子が生成することが、本発明者らの検討の結果判明した。特に、湿式還元の条件として、亜酸化銅粒子のスラリーの温度を、上述した範囲に設定した状態下に、水素化ホウ素ナトリウムをスラリー中に、所定の時間にわたって連続的に添加するという条件を採用することで、表面に微細な凹凸形状を有し、また多孔質体である銅粒子を首尾よく生成させ得ることが判明した。 The cuprous oxide particles produced by the method described above are solid and not porous. Surprisingly, however, when the cuprous oxide particles are wet-reduced with sodium borohydride capable of reducing the reduction potential in the system to -800 mV or less, fine irregularities are formed on the surface while maintaining the shape and dimensions. As a result of the study by the present inventors, it was found that copper particles having a shape and a porous body were formed. In particular, as a condition for wet reduction, a condition is adopted in which sodium borohydride is continuously added to the slurry over a predetermined period of time while the temperature of the cuprous oxide particle slurry is set to the above-described range. As a result, it was found that copper particles having a fine irregular shape on the surface and being a porous body can be successfully generated.
次に、（ロ）の乾式法について説明する。乾式法においては、球形状を有する銅粒子を含むスラリーを、ビーズミル処理する操作に付す。通常、このような操作は、球形状を有する銅粒子から、扁平形状を有する銅粒子を製造するときに行われるものであるところ、本発明者の検討の結果、ビーズミルの処理条件を適切に制御し、従来よりも低エネルギー条件を採用することで、球形状を有する銅粒子から、直方体形状ないし立方体形状を有する銅粒子が塑性変形によって生成することが判明した。 Next, the dry method (b) will be described. In the dry method, a slurry containing copper particles having a spherical shape is subjected to an operation of bead milling. Usually, such an operation is performed when producing copper particles having a flat shape from copper particles having a spherical shape. As a result of the present inventors' investigation, the processing conditions of the bead mill are appropriately controlled. And it became clear that the copper particle which has a rectangular parallelepiped shape or a cube shape is produced | generated by plastic deformation from the copper particle which has a spherical shape by employ | adopting a low energy condition conventionally.
球形状を有する銅粒子を塑性変形させて直方体形状ないし立方体形状を有する銅粒子を生成させるためのビーズミルの処理条件には、ビーズの大きさ、充填率、ビーズミルに印加するエネルギーなどが挙げられる。ビーズの大きさに関しては、０．１０ｍｍ以上１．０ｍｍ以下、特に０．１５ｍｍ以上０．５ｍｍ以下、とりわけ０．２０ｍｍ以上０．５０ｍｍ以下のものを用いることが好ましい。ビーズの充填率に関しては、４０％以上８０％以下、特に４５％以上７０％以下、とりわけ５０％以上７０％以下に設定することが好ましい。 The processing conditions of the bead mill for plastically deforming the copper particles having a spherical shape to generate copper particles having a rectangular parallelepiped shape or a cubic shape include the size of the beads, the filling rate, and the energy applied to the bead mill. Regarding the size of the beads, it is preferable to use a bead having a size of 0.10 mm to 1.0 mm, particularly 0.15 mm to 0.5 mm, particularly 0.20 mm to 0.50 mm. The bead filling rate is preferably set to 40% to 80%, particularly 45% to 70%, particularly 50% to 70%.
ビーズミルに供する球形状の銅粒子は、スラリーの状態とすることが、目的とする形状の銅粒子を首尾よく得ることができる点から好ましい。銅粒子のスラリーの液媒体としては、例えば水、メタノール等の水溶性有機溶媒、及び水と水溶性有機溶媒との混合溶媒などが挙げられる。スラリー中の銅粒子の割合は、１０％以上６０％以下、特に２０％以上５０％以下、とりわけ３０％以上４０％以下であることが好ましい。 The spherical copper particles used in the bead mill are preferably in a slurry state from the viewpoint that the desired shape of copper particles can be successfully obtained. Examples of the liquid medium of the copper particle slurry include water, a water-soluble organic solvent such as methanol, and a mixed solvent of water and a water-soluble organic solvent. The ratio of the copper particles in the slurry is preferably 10% or more and 60% or less, particularly 20% or more and 50% or less, and particularly preferably 30% or more and 40% or less.
目的とする粒径の銅粒子を首尾よく得る観点から、原料である球形状の銅粒子は、その一次粒子の平均径が、１．０μｍ以上１５．０μｍ以下であることが好ましく、１．５μｍ以上１４．５μｍ以下であることが更に好ましく、２．０μｍ以上１４．０μｍ以下であることが一層好ましい。 From the viewpoint of successfully obtaining copper particles having a target particle size, the spherical copper particles as a raw material preferably have an average primary particle diameter of 1.0 μm or more and 15.0 μm or less, and 1.5 μm. The thickness is more preferably 14.5 μm or less and even more preferably 2.0 μm or more and 14.0 μm or less.
以上の各方法によって製造された本発明の銅粉は、これを樹脂及び有機溶媒と混合することで、導電性組成物となされる。樹脂及び有機溶媒としては、導電性組成物に従来用いられてきたものと同様のものを用いることができる。樹脂としては、例えばアクリル樹脂、エポキシ樹脂、エチルセルロース、カルボキシエチルセルロース等が挙げられる。有機溶媒としては、ターピネオール及びジヒドロターピネオール等のテルペン系溶剤や、エチルカルビトール及びブチルカルビトール等のエーテル系溶剤が挙げられる。 The copper powder of the present invention produced by each of the above methods is made into a conductive composition by mixing it with a resin and an organic solvent. As the resin and the organic solvent, those similar to those conventionally used in the conductive composition can be used. Examples of the resin include acrylic resin, epoxy resin, ethyl cellulose, carboxyethyl cellulose, and the like. Examples of the organic solvent include terpene solvents such as terpineol and dihydroterpineol, and ether solvents such as ethyl carbitol and butyl carbitol.
前記の導電性組成物は、これを基材の表面に塗布することで塗膜となされ、該塗膜を、好ましくは加熱下に乾燥させることで導電体が形成される。この導電体においては、導電性組成物中に含まれる銅粉を構成する銅粒子の形状に起因して、該導電体の表面が平坦なものとなる。また、銅粉に含まれる炭素分が少ない場合には、導電体を製造するときに加えられる熱に起因するブリスターの発生が抑制されるので、このことに起因しても、導電体の表面が平坦なものとなる。具体的には、前記の導電性組成物から形成された導電体は、ＪＩＳ Ｂ０６０１に準拠して測定された算術平均粗さＲａが好ましくは１．０μｍ以下、更に好ましくは０．７μｍ以下、一層好ましくは０．５μｍ以下という平滑なものになる。算術平均粗さＲａは、例えば（株）東京精密社のサーフコム １３０Ａを用いて測定することができる。 The conductive composition is applied to the surface of a substrate to form a coating film, and the coating film is preferably dried by heating to form a conductor. In this conductor, the surface of the conductor becomes flat due to the shape of the copper particles constituting the copper powder contained in the conductive composition. In addition, when the carbon content in the copper powder is small, since the generation of blisters due to the heat applied when the conductor is produced is suppressed, the surface of the conductor is also caused by this. It will be flat. Specifically, the conductor formed from the conductive composition preferably has an arithmetic average roughness Ra measured in accordance with JIS B0601 of preferably 1.0 μm or less, more preferably 0.7 μm or less, and more The smoothness is preferably 0.5 μm or less. The arithmetic average roughness Ra can be measured using, for example, Surfcom 130A manufactured by Tokyo Seimitsu Co., Ltd.
前記の導電性組成物から形成された導電体は、導電性組成物中に含まれる銅粉を構成する銅粒子の形状及び炭素分の少なさに起因して、該導電体中での銅粒子の充填率が高くなる。具体的には、前記の導電性組成物から形成された導電体の密度が好ましくは５．０ｇ／ｃｍ３以上、更に好ましくは６．０ｇ／ｃｍ３以上、一層好ましくは６．５ｇ／ｃｍ３以上、更に一層好ましくは７．５ｇ／ｃｍ３以上という高充填なものになる。導電体の密度は、例えば導電体を１ｃｍ×１ｃｍの大きさに切り出し、その厚みと質量を測定し、質量を体積で除すことで算出される。導電体の形成は、導電体組成物をアルミナ基板上に５ｃｍ×５ｃｍの面積で膜厚が５０μｍとなるように印刷等の手段によって施した後、１２０℃で１０分間にわたり空気中で乾燥させることで得られる。 The conductor formed from the conductive composition is a copper particle in the conductor due to the shape of the copper particles constituting the copper powder contained in the conductive composition and the low carbon content. The filling rate becomes higher. Specifically, said the density of the conductive formed from the composition the conductors preferably 5.0 g / cm 3 or more, more preferably 6.0 g / cm 3 or more, more preferably 6.5 g / cm 3 As mentioned above, it becomes still more preferably a high filling of 7.5 g / cm 3 or more. The density of the conductor is calculated, for example, by cutting the conductor into a size of 1 cm × 1 cm, measuring its thickness and mass, and dividing the mass by the volume. The conductor is formed by applying the conductor composition on an alumina substrate by printing or the like so as to have a film thickness of 50 μm in an area of 5 cm × 5 cm, and then drying in air at 120 ° C. for 10 minutes. It is obtained by.
また、前記の導電性組成物から形成された導電体は、その抵抗率が好ましくは、６．０×１０−４Ω・ｃｍ以下、更に好ましくは４．０×１０−４Ω・ｃｍ以下、一層好ましくは３．０×１０−４Ω・ｃｍ以下という低抵抗なものになる。導電体の抵抗率は、例えば、（株）三菱アナリテック社のロレスタＧＰ ＭＣＰ−Ｔ６１０型を用いて、４端子４探針法によって測定することができる。 In addition, the electric conductor formed from the conductive composition preferably has a resistivity of 6.0 × 10 −4 Ω · cm or less, more preferably 4.0 × 10 −4 Ω · cm or less, More preferably, the resistance is as low as 3.0 × 10 −4 Ω · cm or less. The resistivity of the conductor can be measured by, for example, a 4-terminal 4-probe method using a Loresta GP MCP-T610 model manufactured by Mitsubishi Analytech Co., Ltd.
以下、実施例により本発明を更に詳細に説明する。しかしながら本発明の範囲は、かかる実施例に制限されない。特に断らない限り、「％」は「質量％」を意味する。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass%”.
〔実施例１〕
立方体形状銅粒子から構成される銅粉の湿式合成
原料となる立方体状亜酸化銅粒子から構成される銅粉を、特開２００５−２５５４４６号公報の実施例１に記載のとおりに合成した。合成された亜酸化銅粒子の一次粒子の平均径は５．５μｍであった。得られた亜酸化銅粉２００ｇを４０℃の純水１０００ｍＬに分散させた。そこへ７５ｇの水素化ホウ素ナトリウムを純水１５０ｇに溶解させた溶液を、１０分かけて連続的に添加した。その後、反応スラリーを１時間撹拌することで、立方体形状銅粒子から構成される銅粉を湿式合成した。反応終了後、反応液全量を固液分離した。得られた固形分について、純水を用いたデカンテーションを行い、上澄み導電率が１０００μＳ／ｃｍ以下になるまで繰り返した。洗浄物を固形分離し、得られた固形分を常温で減圧乾燥し、目的とする銅粉を得た。得られた銅粉の一次粒子の平均粒径は５．８μｍであり、炭素含有量は０．０８％であった。銅粒子は多孔質体であり、表面に微細な凹凸が形成されていた。得られた銅粉の走査型電子顕微鏡像を図２（ａ）及び（ｂ）に示す。銅粉のＢＥＴ比表面積は４．７ｍ２／ｇであり、〔ＢＥＴ比表面積（ｍ２／ｇ）／一次粒子の平均粒径（μｍ）〕の値が０．８１０であり、〔炭素含有量（％）／ＢＥＴ比表面積（ｍ２／ｇ）〕の値が０．０２であった。また、立方体状銅粒子は、銅粒子の集合体の中で９４個数％であった。
[Example 1]
Wet synthesis of copper powder composed of cubic copper particles Copper powder composed of cubic cuprous oxide particles as a raw material was synthesized as described in Example 1 of JP-A-2005-255446. The average primary particle diameter of the synthesized cuprous oxide particles was 5.5 μm. 200 g of the obtained cuprous oxide powder was dispersed in 1000 mL of pure water at 40 ° C. A solution prepared by dissolving 75 g of sodium borohydride in 150 g of pure water was continuously added thereto over 10 minutes. Thereafter, the reaction slurry was stirred for 1 hour to wet-synthesize copper powder composed of cubic copper particles. After completion of the reaction, the entire reaction solution was separated into solid and liquid. The obtained solid content was decanted with pure water and repeated until the supernatant conductivity was 1000 μS / cm or less. The washed product was separated into solids, and the resulting solid content was dried under reduced pressure at room temperature to obtain the intended copper powder. The average particle diameter of the primary particles of the obtained copper powder was 5.8 μm, and the carbon content was 0.08%. The copper particles were a porous body, and fine irregularities were formed on the surface. Scanning electron microscope images of the obtained copper powder are shown in FIGS. 2 (a) and 2 (b). The copper powder has a BET specific surface area of 4.7 m 2 / g, a value of [BET specific surface area (m 2 / g) / average primary particle diameter (μm)] of 0.810, and [carbon content] (%) / BET specific surface area (m 2 / g)] was 0.02. Further, the number of cubic copper particles was 94% by number in the aggregate of copper particles.
得られた銅粉２０ｇを、エチルセルロース５．０％を含むターピネオール５．０ｇに加えて混練することでペーストを調製した。得られたペーストを、アルミナ基板上に、ギャップ５０μｍのアプリケーターを用いて塗布することで塗膜を形成した。この塗膜を、大気下１２０℃で１０分間乾燥させて導電体を得た。得られた導電体の算術平均粗さＲａを測定したところ、０．２５μｍであった。また、得られた導電体の密度は７．１ｇ／ｃｍ３であり、抵抗率は２．５×１０−４Ω・ｃｍであった。 A paste was prepared by adding 20 g of the obtained copper powder to 5.0 g of terpineol containing 5.0% of ethylcellulose and kneading. The obtained paste was applied on an alumina substrate using an applicator with a gap of 50 μm to form a coating film. This coating film was dried at 120 ° C. for 10 minutes in the air to obtain a conductor. When arithmetic mean roughness Ra of the obtained conductor was measured, it was 0.25 μm. Moreover, the density of the obtained conductor was 7.1 g / cm 3 and the resistivity was 2.5 × 10 −4 Ω · cm.
〔実施例２〕
立方体形状銅粒子から構成される銅粉のビーズミル処理による製造
原料となる球形状銅粒子から構成される銅粉を、特開平１０−３３０８０１号公報の実施例１に記載のとおりに合成した。この原料銅粉の一次粒子の平均粒径は５．５μｍであった。この銅粉１．０ｋｇとメタノール５．０ｋｇとを混合してスラリーとなし、このスラリーを媒体分散ミルであるダイノーミル内に入れた。また、メディアとして直径０．２ｍｍのジルコニア製ビーズを用い、これを充填率７０％でダイノーミル内に入れた。この状態下にダイノーミルを５分間にわたり運転して、球形状銅粒子を塑性変形させてその立方体化を行った。ミル処理後、固形分を分離し、得られた固形分を常温で減圧乾燥した。得られた銅粉の一次粒子の平均粒径は５．６μｍであり、炭素含有量は０．０４％であった。得られた銅粉の走査型電子顕微鏡像を図３に示す。この銅粉を用い、実施例１と同様にして導電体を形成し、この導電体の算術平均粗さＲａ、充填率及び抵抗率を測定した。その結果を以下の表１に示す。また、直方体状銅粒子は、銅粒子の集合体の中で８１個数％であった。
[Example 2]
Production of copper powder composed of cubic copper particles by bead mill treatment Copper powder composed of spherical copper particles as a raw material was synthesized as described in Example 1 of JP-A-10-330801. The average particle diameter of the primary particles of this raw material copper powder was 5.5 μm. 1.0 kg of this copper powder and 5.0 kg of methanol were mixed to form a slurry, and this slurry was put into a dyno mill which is a medium dispersion mill. Further, zirconia beads having a diameter of 0.2 mm were used as media, and this was put in a dyno mill at a filling rate of 70%. Under this condition, the dyno mill was operated for 5 minutes to plastically deform the spherical copper particles and to form a cube. After milling, the solid content was separated, and the obtained solid content was dried under reduced pressure at room temperature. The average particle diameter of the primary particles of the obtained copper powder was 5.6 μm, and the carbon content was 0.04%. A scanning electron microscope image of the obtained copper powder is shown in FIG. Using this copper powder, a conductor was formed in the same manner as in Example 1, and the arithmetic average roughness Ra, filling rate, and resistivity of this conductor were measured. The results are shown in Table 1 below. Moreover, the rectangular parallelepiped copper particles were 81% by number in the aggregate of copper particles.
〔実施例３〕
立方体形状銅粒子から構成される銅粉のビーズミル処理による製造
実施例２において、ダイノーミルの運転時間を１０分に延ばした以外は、実施例２と同様にして、立方体形状銅粒子から構成される銅粉を製造した。得られた銅粉の一次粒子の平均粒径は６．２μｍであり、炭素含有量は０．０４％であった。得られた銅粉の走査型電子顕微鏡像を図４に示す。この銅粉を用い、実施例１と同様にして導電体を形成し、この導電体の算術平均粗さＲａ、充填率及び抵抗率を測定した。その結果を以下の表１に示す。また、直方体状銅粒子は、銅粒子の集合体の中で８８個数％であった。
Example 3
Production of copper powder composed of cube-shaped copper particles by bead mill treatment In Example 2, copper composed of cube-shaped copper particles was performed in the same manner as in Example 2 except that the operation time of the dyno mill was extended to 10 minutes. Powder was produced. The average particle diameter of primary particles of the obtained copper powder was 6.2 μm, and the carbon content was 0.04%. A scanning electron microscope image of the obtained copper powder is shown in FIG. Using this copper powder, a conductor was formed in the same manner as in Example 1, and the arithmetic average roughness Ra, filling rate, and resistivity of this conductor were measured. The results are shown in Table 1 below. Moreover, the rectangular parallelepiped copper particle was 88 number% in the aggregate | assembly of a copper particle.
〔比較例１〕
本比較例は、実施例１において、亜酸化銅の還元を、水素化ホウ素ナトリウムではなくヒドラジンを用いて行った例である。それ以外は、実施例１と同様にして銅粉を製造した。得られた銅粉を構成する銅粒子は、略球形状のものであった。銅粉の一次粒子の平均粒径は２．１μｍであり、炭素含有量は０．３５％であった。得られた銅粉の走査型電子顕微鏡像を図５に示す。この銅粉を用い、実施例１と同様にして導電体を形成し、この導電体の算術平均粗さＲａ、充填率及び抵抗率を測定した。その結果を以下の表１に示す。
[Comparative Example 1]
This comparative example is an example in which the reduction of cuprous oxide in Example 1 was performed using hydrazine instead of sodium borohydride. Other than that produced the copper powder like Example 1. FIG. The copper particles constituting the obtained copper powder were substantially spherical. The average particle diameter of the primary particles of the copper powder was 2.1 μm, and the carbon content was 0.35%. A scanning electron microscope image of the obtained copper powder is shown in FIG. Using this copper powder, a conductor was formed in the same manner as in Example 1, and the arithmetic average roughness Ra, filling rate, and resistivity of this conductor were measured. The results are shown in Table 1 below.
〔比較例２〕
本比較例は、実施例２で用いた原料の銅粉そのものを用いた例である。この銅粉の一次粒子の平均粒径は５．５μｍであり、炭素含有量は０．２２％であった。この銅粉の走査型電子顕微鏡像を図６に示す。この銅粉を用い、実施例１と同様にして導電体を形成し、この導電体の算術平均粗さＲａ、充填率及び抵抗率を測定した。その結果を以下の表１に示す。
[Comparative Example 2]
This comparative example is an example using the raw material copper powder itself used in Example 2. The average particle size of the primary particles of the copper powder was 5.5 μm, and the carbon content was 0.22%. A scanning electron microscope image of this copper powder is shown in FIG. Using this copper powder, a conductor was formed in the same manner as in Example 1, and the arithmetic average roughness Ra, filling rate, and resistivity of this conductor were measured. The results are shown in Table 1 below.
〔比較例３〕
本比較例は、特許文献１の実施例３に記載のとおりに銅粉を合成した例である。得られた銅粉の一次粒子の平均粒径は５２ｎｍであり、炭素含有量は２．１％であった。この銅粉を用い、実施例１と同様にして導電体を形成し、この導電体の算術平均粗さＲａ、充填率及び抵抗率を測定した。その結果を以下の表１に示す。また、直方体状銅粒子は、銅粒子の集合体の中で９５個数％であった。
[Comparative Example 3]
This comparative example is an example in which copper powder was synthesized as described in Example 3 of Patent Document 1. The average particle diameter of the primary particles of the obtained copper powder was 52 nm, and the carbon content was 2.1%. Using this copper powder, a conductor was formed in the same manner as in Example 1, and the arithmetic average roughness Ra, filling rate, and resistivity of this conductor were measured. The results are shown in Table 1 below. Moreover, the rectangular parallelepiped copper particles were 95% by number in the aggregate of copper particles.
表１に示す結果から明らかなとおり、各実施例で得られた銅粉を用いて形成された導電体は、比較例で得られた銅粉を用いて形成された導電体に比べて、表面の平滑性及び充填率が高く、また抵抗率が低いものであることが判る。特に、比較例３は、導電体の表面粗さが他の比較例に比べて低いものの、充填性が悪く密度が低いことに起因して、抵抗率が高くなってしまった。 As is clear from the results shown in Table 1, the conductor formed using the copper powder obtained in each example is a surface compared to the conductor formed using the copper powder obtained in the comparative example. It can be seen that the smoothness and filling rate of the film are high and the resistivity is low. In particular, although Comparative Example 3 had a lower surface roughness than the other Comparative Examples, the resistivity was high due to poor filling properties and low density.
Claims (9)
一次粒子の平均粒径が１μｍ以上１５μｍ以下であり、
前記粒子の六つの面すべてでアスペクト比が１以上５以下であり、
炭素の含有量（質量％）／ＢＥＴ比表面積（ｍ ２ ／ｇ）の値が１．０以下であり、
ＢＥＴ比表面積（ｍ ２ ／ｇ）／一次粒子径の平均粒径（μｍ）の値が０．０２以上３．０以下である銅粉。 Consists of copper particles having a rectangular parallelepiped shape,
Ri average particle diameter der than 15μm below 1μm of primary particles,
The aspect ratio is 1 or more and 5 or less on all six faces of the particle,
The value of carbon content (mass%) / BET specific surface area (m 2 / g) is 1.0 or less,
BET specific surface area (m 2 / g) / primary particle diameter average particle diameter ([mu] m) value is 0.02 to 3.0 der Ru copper powder of.
一次粒子の平均粒径が１．０μｍ以上１５．０μｍ以下である直方体形状を有する亜酸化銅粒子を、系中の還元電位を−８００ｍＶ以下とすることによって湿式還元する工程を有する銅粉の製造方法。 A copper powder production method comprising copper particles having a rectangular parallelepiped shape, wherein the average particle size of primary particles is 1 μm or more and 15 μm or less ,
Production of copper powder having a step of wet-reducing cuprous oxide particles having a rectangular parallelepiped shape having an average primary particle size of 1.0 μm or more and 15.0 μm or less by reducing the reduction potential in the system to −800 mV or less. Method.
一次粒子の平均粒径が１．０μｍ以上１５．０μｍ以下である球形状を有する銅粒子を含むスラリーを、ビーズミル処理する工程を有する銅粉の製造方法。 It is a manufacturing method of the copper powder according to claim 1,
The manufacturing method of copper powder which has the process of carrying out the bead mill process of the slurry containing the copper particle which has a spherical shape whose average particle diameter of a primary particle is 1.0 micrometer or more and 15.0 micrometers or less.
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