JP6922648B2 - Composite copper particles, copper ink, and methods for manufacturing composite copper particles - Google Patents
Composite copper particles, copper ink, and methods for manufacturing composite copper particles Download PDFInfo
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims description 448
- 239000010949 copper Substances 0.000 title claims description 448
- 229910052802 copper Inorganic materials 0.000 title claims description 448
- 239000002245 particle Substances 0.000 title claims description 275
- 239000002131 composite material Substances 0.000 title claims description 78
- 238000000034 method Methods 0.000 title claims description 17
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 239000010419 fine particle Substances 0.000 claims description 81
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 44
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 28
- 125000004432 carbon atom Chemical group C* 0.000 claims description 28
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 claims description 28
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 22
- 235000019253 formic acid Nutrition 0.000 claims description 22
- 150000001735 carboxylic acids Chemical class 0.000 claims description 15
- 229960000583 acetic acid Drugs 0.000 claims description 14
- 239000012362 glacial acetic acid Substances 0.000 claims description 14
- 235000019260 propionic acid Nutrition 0.000 claims description 14
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000012266 salt solution Substances 0.000 claims description 12
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 9
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 7
- 239000003638 chemical reducing agent Substances 0.000 claims description 7
- 229910001431 copper ion Inorganic materials 0.000 claims description 7
- 150000002763 monocarboxylic acids Chemical class 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 58
- 239000000976 ink Substances 0.000 description 51
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 29
- 230000000052 comparative effect Effects 0.000 description 26
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 24
- 238000004381 surface treatment Methods 0.000 description 24
- 235000014113 dietary fatty acids Nutrition 0.000 description 16
- 229930195729 fatty acid Natural products 0.000 description 16
- 239000000194 fatty acid Substances 0.000 description 16
- 150000004665 fatty acids Chemical class 0.000 description 16
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 15
- 238000002360 preparation method Methods 0.000 description 15
- 239000000126 substance Substances 0.000 description 15
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 12
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 9
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 9
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 9
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 9
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine hydrate Chemical compound O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- 238000000746 purification Methods 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 239000000758 substrate Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 150000002762 monocarboxylic acid derivatives Chemical class 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- 238000013459 approach Methods 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000012298 atmosphere Substances 0.000 description 4
- 238000009835 boiling Methods 0.000 description 4
- 239000011246 composite particle Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- WWZKQHOCKIZLMA-UHFFFAOYSA-N Caprylic acid Natural products CCCCCCCC(O)=O WWZKQHOCKIZLMA-UHFFFAOYSA-N 0.000 description 3
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 3
- GONOPSZTUGRENK-UHFFFAOYSA-N benzyl(trichloro)silane Chemical compound Cl[Si](Cl)(Cl)CC1=CC=CC=C1 GONOPSZTUGRENK-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000012046 mixed solvent Substances 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- HXKKHQJGJAFBHI-UHFFFAOYSA-N 1-aminopropan-2-ol Chemical compound CC(O)CN HXKKHQJGJAFBHI-UHFFFAOYSA-N 0.000 description 2
- GYSCBCSGKXNZRH-UHFFFAOYSA-N 1-benzothiophene-2-carboxamide Chemical compound C1=CC=C2SC(C(=O)N)=CC2=C1 GYSCBCSGKXNZRH-UHFFFAOYSA-N 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 2
- GHVNFZFCNZKVNT-UHFFFAOYSA-N Decanoic acid Natural products CCCCCCCCCC(O)=O GHVNFZFCNZKVNT-UHFFFAOYSA-N 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 150000001721 carbon Chemical group 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229940102253 isopropanolamine Drugs 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 239000003223 protective agent Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000009918 complex formation Effects 0.000 description 1
- LTYZGLKKXZXSEC-UHFFFAOYSA-N copper dihydride Chemical compound [CuH2] LTYZGLKKXZXSEC-UHFFFAOYSA-N 0.000 description 1
- 229910000050 copper hydride Inorganic materials 0.000 description 1
- -1 for example Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
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- Conductive Materials (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Description
本発明は、銅ベース粒子の表面に銅微粒子が被着された複合銅粒子に関する。 The present invention relates to composite copper particles in which copper fine particles are adhered to the surface of copper base particles.
また、本発明は、本発明の複合銅粒子を含んだ銅インクに関する。 The present invention also relates to a copper ink containing the composite copper particles of the present invention.
また、本発明は、本発明の複合銅粒子を製造するのに適した、複合銅粒子の製造方法に関する。 The present invention also relates to a method for producing composite copper particles, which is suitable for producing the composite copper particles of the present invention.
電子機器などに内蔵される基板などに導電膜を形成するために、金属粒子を溶媒やバインダーに分散させた導電インク（「導電ペースト」と呼ばれる場合もある）が、広く使用されている。具体的には、基板などに、導電インクを所望のパターン形状に塗布したうえで、加熱して焼付けをおこない、導電膜を形成する。 Conductive ink (sometimes called "conductive paste") in which metal particles are dispersed in a solvent or a binder is widely used in order to form a conductive film on a substrate or the like built in an electronic device or the like. Specifically, a conductive ink is applied to a substrate or the like in a desired pattern shape, and then heated and baked to form a conductive film.
導電インクにおいては、通常、できるだけ焼付けに必要な温度が低いことが好ましい。容易に、導電膜を形成することができるからである。また、導電膜を形成する対象（基板など）の材質の選択自由度が高まるからである。 In conductive inks, it is usually preferable that the temperature required for baking is as low as possible. This is because the conductive film can be easily formed. In addition, the degree of freedom in selecting the material of the object (such as the substrate) on which the conductive film is formed is increased.
特許文献１（特開２０１０-２８５６７８号公報）に、焼付けに必要な温度が低い銅インク（銅ペースト）が開示されている。特許文献１に開示された銅インクは、平均粒子径が１μｍ〜２０μｍの銅ベース粒子（金属銅粒子）の表面に、平均粒子径が２０ｎｍ〜３５０ｎｍの銅微粒子（水素化銅微粒子）を被着させた複合銅粒子（銅複合粒子）を、樹脂バインダーに分散させたものからなる。 Patent Document 1 (Japanese Unexamined Patent Publication No. 2010-285678) discloses a copper ink (copper paste) having a low temperature required for baking. In the copper ink disclosed in Patent Document 1, copper fine particles (copper hydride fine particles) having an average particle diameter of 20 nm to 350 nm are adhered to the surface of copper base particles (metal copper particles) having an average particle diameter of 1 μm to 20 μm. It is composed of the composite copper particles (copper composite particles) dispersed in a resin binder.
特許文献１に開示された銅インクは、基板などに塗布した後、たとえば１５０℃程度の低温で焼付けることにより、銅微粒子が融解して銅ベース粒子と接合するとともに、銅微粒子どうしが接合して、銅導電膜が形成される。 The copper ink disclosed in Patent Document 1 is applied to a substrate or the like and then baked at a low temperature of, for example, about 150 ° C., so that the copper fine particles are melted and bonded to the copper base particles, and the copper fine particles are bonded to each other. A copper conductive film is formed.
特許文献１に開示された複合銅粒子は、銅イオンを含む金属塩溶液（水溶液）に、銅ベース粒子を分散させたうえ、還元剤を添加することによって、銅ベース粒子の表面に銅微粒子を析出させて作製されている。 In the composite copper particles disclosed in Patent Document 1, copper-based particles are dispersed in a metal salt solution (aqueous solution) containing copper ions, and a reducing agent is added to form copper fine particles on the surface of the copper-based particles. It is produced by precipitating.
複合銅粒子を作製する場合、通常、先に銅ベース粒子となる銅粒子を作製しておき、時間をおいてから、銅ベース粒子の表面に銅微粒子を形成する（析出させる）場合が多い。あるいは、市販されている銅粒子を購入し、その銅粒子を銅ベース粒子に使用し、その表面に銅微粒子を形成する場合もある。一方、銅粒子は、表面が非常に酸化しやすい。 When producing composite copper particles, it is often the case that copper particles to be copper-based particles are produced first, and after a while, copper fine particles are formed (precipitated) on the surface of the copper-based particles. Alternatively, commercially available copper particles may be purchased and used as copper base particles to form copper fine particles on the surface thereof. On the other hand, the surface of copper particles is very easy to oxidize.
そこで、従来、銅ベース粒子に使用する銅粒子は、作製過程において、あるいは、作製後に、表面にデカン酸などの脂肪酸を配位させる場合が多かった。 Therefore, conventionally, copper particles used for copper-based particles are often coordinated with fatty acids such as decanoic acid on the surface during or after the production.
しかしながら、表面に脂肪酸が配位された銅粒子を銅ベース粒子に使用し、その表面に銅微粒子を形成して複合銅粒子を作製し、その複合銅粒子を含む銅インクを作製した場合には、次のような問題があった。 However, when copper particles in which fatty acids are coordinated on the surface are used as copper base particles, copper fine particles are formed on the surface to produce composite copper particles, and a copper ink containing the composite copper particles is produced. , There was the following problem.
まず、脂肪酸は、主鎖が長く、沸点も高いため、熱分解性が悪いという問題があった。そのため、表面に脂肪酸が配位された銅粒子を銅ベース粒子に使用し、その表面に銅微粒子を形成した複合銅粒子を含む銅インクは、焼付け後に、銅ベース粒子の表面に炭素などが残渣として残ってしまい、導電性パスの形成を妨げ、銅導電膜のシート抵抗率が高くなってしまうという問題があった。 First, fatty acids have a long main chain and a high boiling point, so that they have a problem of poor thermal decomposability. Therefore, copper ink containing composite copper particles in which copper particles in which fatty acids are coordinated on the surface are used as copper base particles and copper fine particles are formed on the surface of the copper ink has carbon and the like remaining on the surface of the copper base particles after baking. There is a problem that the sheet resistivity of the copper conductive film becomes high, which hinders the formation of the conductive path.
また、脂肪酸は、主鎖が長いため、銅微粒子の接近を妨げるという問題があった。そのため、複合銅粒子を含む銅インクを焼付けても、銅ベース粒子に銅微粒子が十分に接合せず、良好な導電性パスが形成されず、銅導電膜のシート抵抗率が高くなってしまうという問題があった。 Further, since the fatty acid has a long main chain, there is a problem that it hinders the approach of copper fine particles. Therefore, even if the copper ink containing the composite copper particles is baked, the copper fine particles are not sufficiently bonded to the copper base particles, a good conductive path is not formed, and the sheet resistivity of the copper conductive film becomes high. There was a problem.
本発明は、上述した従来の問題を解決するためになされたものであり、その手段として本発明の複合銅粒子は、銅ベース粒子と、銅ベース粒子の表面に被着された、銅ベース粒子よりも粒子径が小さい銅微粒子と、を備え、銅ベース粒子は、表面の少なくとも一部に、炭素数が１以上、３以下の低級カルボン酸が配位され、銅微粒子が、低級カルボン酸を介して銅ベース粒子に被着され、低級カルボン酸が、ギ酸、氷酢酸、プロピオン酸のいずれか１つであるものとする。 The present invention has been made to solve the above-mentioned conventional problems, and as a means thereof, the composite copper particles of the present invention are the copper-based particles and the copper-based particles adhered to the surface of the copper-based particles. The copper-based particles are provided with copper fine particles having a particle size smaller than that of the copper-based particles, in which a lower carboxylic acid having 1 or more and 3 or less carbon atoms is coordinated on at least a part of the surface, and the copper fine particles contain the lower carboxylic acid. It is assumed that the lower carboxylic acid is one of formic acid, glacial acetic acid, and propionic acid, which is adhered to the copper-based particles through the particles.
なお、炭素数が１以上、３以下の低級カルボン酸は、一般に、デカン酸などの脂肪酸に比べて、主鎖が短く、沸点が低く、熱分解性に優れている。 Lower carboxylic acids having 1 or more and 3 or less carbon atoms generally have a shorter main chain, a lower boiling point, and excellent thermal decomposability as compared with fatty acids such as decanoic acid.
低級カルボン酸は、モノカルボン酸、または、ジカルボン酸であることが好ましい。炭素数が少なくても、カルボキシ基の数が多くなると、熱分解性が悪くなる傾向にあり、また銅微粒子の接近を妨げる傾向にあるからである。 The lower carboxylic acid is preferably a monocarboxylic acid or a dicarboxylic acid. This is because even if the number of carbon atoms is small, if the number of carboxy groups is large, the thermal decomposability tends to be deteriorated, and the approach of copper fine particles tends to be hindered.
低級カルボン酸は、ギ酸、氷酢酸、プロピオン酸のいずれか１つであるものとする。これらの低級カルボン酸が表面に配位された銅粒子を銅ベース粒子に使用し、その表面に銅微粒子を形成して複合銅粒子を作製し、その複合銅粒子を使用して作製した銅インクを使用することにより、シート抵抗率の低い銅導電膜を形成できることが確認できた。 Lower carboxylic acid is formic acid, glacial acetic acid, as is any one of propionic acid. Copper particles in which these lower carboxylic acids are coordinated on the surface are used as copper base particles, copper fine particles are formed on the surface to prepare composite copper particles, and a copper ink prepared by using the composite copper particles. It was confirmed that a copper conductive film having a low sheet resistivity can be formed by using the above.
銅ベース粒子の平均粒径が、０．１μｍ以上、１０μｍ以下であり、銅微粒子の平均粒径が、０より大きく、１００ｎｍ以下であることが好ましい。銅ベース粒子の平均粒径が０．１μｍよりも小さいと、銅ベース粒子の表面に析出させる銅微粒子の量が、非常に多く必要になるからである。また、銅ベース粒子の平均粒径が１０μｍを超えると、銅インクを焼付けても、銅ベース粒子と銅微粒子との接合が不十分になり、良好な導電性パスを形成することができず、銅導電膜のシート抵抗率が高くなる虞があるからである。また、銅微粒子の平均粒径が０であると（銅微粒子が被着されないと）、銅インクを焼付けても、銅ベース粒子と銅微粒子との接合および銅微粒子どうしの接合による導電性パスを形成することができないからである。また、銅微粒子の平均粒径が１００ｎｍを超えると、銅インクを焼付けても、銅微粒子が十分に融解せず、良好な導電性パスを形成することができず、銅導電膜のシート抵抗率が高くなる虞があるからである。 It is preferable that the average particle size of the copper-based particles is 0.1 μm or more and 10 μm or less, and the average particle size of the copper fine particles is larger than 0 and 100 nm or less. This is because if the average particle size of the copper-based particles is smaller than 0.1 μm, a very large amount of copper fine particles to be precipitated on the surface of the copper-based particles is required. Further, when the average particle size of the copper-based particles exceeds 10 μm, even if the copper ink is baked, the bonding between the copper-based particles and the copper fine particles becomes insufficient, and a good conductive path cannot be formed. This is because the sheet resistivity of the copper conductive film may increase. Further, when the average particle size of the copper fine particles is 0 (when the copper fine particles are not adhered), even if the copper ink is baked, the conductive path due to the bonding between the copper base particles and the copper fine particles and the bonding between the copper fine particles is performed. This is because it cannot be formed. Further, when the average particle size of the copper fine particles exceeds 100 nm, even if the copper ink is baked, the copper fine particles are not sufficiently melted and a good conductive path cannot be formed, and the sheet resistivity of the copper conductive film cannot be formed. This is because there is a risk that
なお、銅ベース粒子の平均粒径は、透過型電子顕微鏡（Transmission Electron Microscope；以下ＴＥＭと記す。）像または走査型電子顕微鏡（Scanning Electron Microscope；以下ＳＥＭと記す。）の中から無作為に選ばれた１００個の銅ベース粒子の粒子径を測定し、平均することにより算出することができる。また、銅微粒子の平均粒径は、ＴＥＭ像またはＳＥＭ像の中から無作為に選ばれた１００個の銅微粒子の粒子径を測定し、平均することにより算出することができる。 The average particle size of the copper-based particles is randomly selected from a transmission electron microscope (hereinafter referred to as TEM) image or a scanning electron microscope (hereinafter referred to as SEM). It can be calculated by measuring and averaging the particle diameters of the 100 copper-based particles. The average particle size of the copper fine particles can be calculated by measuring and averaging the particle sizes of 100 copper fine particles randomly selected from a TEM image or an SEM image.
また、本発明の銅インクは、本発明の複合銅粒子と、溶媒と、を含むものからなる。 Further, the copper ink of the present invention comprises the composite copper particles of the present invention and a solvent.
また、本発明の複合銅粒子の製造方法は、ベース銅粒子を用意する工程と、ベース銅粒子を炭素数が１以上、３以下の低級カルボン酸に浸漬し、銅ベース粒子の表面の少なくとも一部に、低級カルボン酸を配位させる工程と、銅イオンを含む金属塩溶液を用意する工程と、金属塩溶液に、表面に低級カルボン酸が配位された銅ベース粒子を分散させる工程と、銅ベース粒子が分散された金属塩溶液に還元剤を添加し、銅ベース粒子の表面に、低級カルボン酸を介して、銅ベース粒子よりも粒子径が小さい銅微粒子を析出させる工程と、を備えたものとする。 Further, the method for producing composite copper particles of the present invention includes a step of preparing base copper particles and a step of immersing the base copper particles in a lower carboxylic acid having 1 or more and 3 or less carbon atoms, and at least one of the surfaces of the copper base particles. A step of coordinating a lower carboxylic acid in a portion, a step of preparing a metal salt solution containing copper ions, and a step of dispersing copper-based particles in which the lower carboxylic acid is coordinated on the surface in the metal salt solution. A step of adding a reducing agent to a metal salt solution in which copper-based particles are dispersed and precipitating copper fine particles having a particle size smaller than that of the copper-based particles on the surface of the copper-based particles via a lower carboxylic acid is provided. It shall be.
本発明の複合銅粒子の製造方法において、低級カルボン酸は、モノカルボン酸、または、ジカルボン酸であることが好ましい。また、低級カルボン酸は、ギ酸、氷酢酸、プロピオン酸のいずれか１つであることが好ましい。また、銅ベース粒子の平均粒径が、０．１μｍ以上、１０μｍ以下であり、銅微粒子の平均粒径が、０より大きく、１００ｎｍ以下であることが好ましい。それぞれの好ましい理由は、本発明の複合銅粒子の説明において、上述したとおりである。 In the method for producing composite copper particles of the present invention, the lower carboxylic acid is preferably a monocarboxylic acid or a dicarboxylic acid. The lower carboxylic acid is preferably any one of formic acid, glacial acetic acid, and propionic acid. Further, it is preferable that the average particle size of the copper-based particles is 0.1 μm or more and 10 μm or less, and the average particle size of the copper fine particles is larger than 0 and 100 nm or less. The preferred reasons for each are as described above in the description of the composite copper particles of the present invention.
本発明の複合銅粒子は、銅ベース粒子の表面の少なくとも一部に、炭素数が１以上、３以下の低級カルボン酸が配位され、その低級カルボン酸を介して銅微粒子が被着されているため、本発明の複合銅粒子を含む銅インクを使用すれば、シート抵抗率の低い銅導電膜を形成することができる。 In the composite copper particles of the present invention, a lower carboxylic acid having 1 or more and 3 or less carbon atoms is coordinated on at least a part of the surface of the copper-based particles, and copper fine particles are adhered via the lower carboxylic acid. Therefore, if a copper ink containing the composite copper particles of the present invention is used, a copper conductive film having a low sheet resistivity can be formed.
また、本発明の複合銅粒子の製造方法によれば、本発明の複合銅粒子を容易に製造することができる。 Further, according to the method for producing composite copper particles of the present invention, the composite copper particles of the present invention can be easily produced.
以下、本発明を実施するための形態について説明する。 Hereinafter, modes for carrying out the present invention will be described.
（複合銅粒子）
本発明の複合銅粒子は、銅ベース粒子を備える。銅ベース粒子は、表面に銅微粒子を析出させる、ベースとなる銅粒子である。
(Composite copper particles)
The composite copper particles of the present invention include copper-based particles. Copper-based particles are base copper particles that precipitate copper fine particles on the surface.
銅ベース粒子は、平均粒径が、０．１μｍ以上、１０μｍ以下であることが好ましい。銅ベース粒子の平均粒径が０．１μｍよりも小さいと、銅ベース粒子の表面に析出させる銅微粒子の量が、非常に多く必要になるからである。また、銅ベース粒子の平均粒径が１０μｍを超えると、銅インクを焼付けても、銅ベース粒子と銅微粒子との接合が不十分になり、良好な導電性パスを形成することができず、銅導電膜のシート抵抗率が高くなる虞があるからである。 The copper-based particles preferably have an average particle size of 0.1 μm or more and 10 μm or less. This is because if the average particle size of the copper-based particles is smaller than 0.1 μm, a very large amount of copper fine particles to be precipitated on the surface of the copper-based particles is required. Further, when the average particle size of the copper-based particles exceeds 10 μm, even if the copper ink is baked, the bonding between the copper-based particles and the copper fine particles becomes insufficient, and a good conductive path cannot be formed. This is because the sheet resistivity of the copper conductive film may increase.
銅ベース粒子の表面の少なくとも一部に、炭素数が１以上、３以下の低級カルボン酸が配位されている。炭素数１のカルボン酸としては、たとえば、ギ酸をあげることができる。炭素数２のカルボン酸としては、たとえば、氷酢酸、シュウ酸をあげることができる。炭素数３のカルボン酸としては、たとえば、プロピオン酸、マロン酸をあげることができる。 A lower carboxylic acid having 1 or more and 3 or less carbon atoms is coordinated on at least a part of the surface of the copper-based particles. As the carboxylic acid having 1 carbon atom, formic acid can be mentioned, for example. Examples of the carboxylic acid having 2 carbon atoms include glacial acetic acid and oxalic acid . Examples of the carboxylic acid having 3 carbon atoms include propionic acid and malonic acid .
炭素数が１以上、３以下の低級カルボン酸は、脂肪酸などに比べて、主鎖が短く、沸点も低く、熱分解性に優れている。そのため、本発明の複合銅粒子を含む銅インクは、焼付けた後に、銅ベース粒子の表面に、炭素などの残渣が残りにくい。したがって、本発明の複合銅粒子を含む銅インクを使用すれば、炭素などの残渣が導電性パスの形成の妨げとなりにくく、シート抵抗率の低い銅導電膜を形成することができる。 Lower carboxylic acids having 1 or more and 3 or less carbon atoms have a shorter main chain, a lower boiling point, and excellent thermal decomposability as compared with fatty acids and the like. Therefore, the copper ink containing the composite copper particles of the present invention is unlikely to leave residues such as carbon on the surface of the copper-based particles after baking. Therefore, if the copper ink containing the composite copper particles of the present invention is used, the residue such as carbon does not easily hinder the formation of the conductive path, and a copper conductive film having a low sheet resistivity can be formed.
また、炭素数が１以上、３以下の低級カルボン酸は、脂肪酸などに比べて、主鎖が短く、銅微粒子の接近を妨げにくい。そのため、本発明の複合銅粒子を含む銅インクは、焼付けにより、銅ベース粒子と銅微粒子とが良好に接合する。したがって、本発明の複合銅粒子を含む銅インクを使用すれば、良好な導電性パスを形成することができ、シート抵抗率の低い銅導電膜を形成することができる。 Further, a lower carboxylic acid having 1 or more and 3 or less carbon atoms has a shorter main chain than fatty acids and the like, and is less likely to prevent the approach of copper fine particles. Therefore, in the copper ink containing the composite copper particles of the present invention, the copper base particles and the copper fine particles are satisfactorily bonded by baking. Therefore, if the copper ink containing the composite copper particles of the present invention is used, a good conductive path can be formed, and a copper conductive film having a low sheet resistivity can be formed.
炭素数が１以上、３以下の低級カルボン酸は、モノカルボン酸、または、ジカルボン酸であることが好ましい。炭素数が少なくても、カルボキシ基の数が多くなると、熱分解性が悪くなる傾向にあり、また銅微粒子の接近を妨げる傾向にあるからである。 The lower carboxylic acid having 1 or more and 3 or less carbon atoms is preferably a monocarboxylic acid or a dicarboxylic acid. This is because even if the number of carbon atoms is small, if the number of carboxy groups is large, the thermal decomposability tends to be deteriorated, and the approach of copper fine particles tends to be hindered.
モノカルボン酸として、ギ酸、氷酢酸、プロピオン酸をあげることができる。ジカルボン酸として、シュウ酸、マロン酸をあげることができる。 Examples of monocarboxylic acids include formic acid, glacial acetic acid, and propionic acid. Examples of the dicarboxylic acid include oxalic acid and malonic acid.
本発明の複合銅粒子は、銅微粒子を備える。銅微粒子は、上述した、炭素数が１以上、３以下の低級カルボン酸を介して銅ベース粒子に被着されている。 The composite copper particles of the present invention include copper fine particles. The copper fine particles are adhered to the copper base particles via the above-mentioned lower carboxylic acid having 1 or more and 3 or less carbon atoms.
銅微粒子は、平均粒径が、０より大きく、１００ｎｍ以下であることが好ましい。銅微粒子の平均粒径が０であると（銅微粒子が被着されないと）、銅インクを焼付けても、銅ベース粒子と銅微粒子との接合および銅微粒子どうしの接合による導電性パスを形成することができないからである。また、銅微粒子の平均粒径が１００ｎｍを超えると、銅インクを焼付けても、銅微粒子が十分に融解せず、良好な導電性パスを形成することができず、銅導電膜のシート抵抗率が高くなる虞があるからである。 The average particle size of the copper fine particles is preferably larger than 0 and preferably 100 nm or less. When the average particle size of the copper fine particles is 0 (when the copper fine particles are not adhered), even if the copper ink is baked, a conductive path is formed by joining the copper base particles and the copper fine particles and joining the copper fine particles to each other. Because it cannot be done. Further, when the average particle size of the copper fine particles exceeds 100 nm, even if the copper ink is baked, the copper fine particles are not sufficiently melted and a good conductive path cannot be formed, and the sheet resistivity of the copper conductive film cannot be formed. This is because there is a risk that
（銅インク）
銅インクは、上述した複合銅粒子を、溶媒に分散させたものからなる。
(Copper ink)
The copper ink comprises the above-mentioned composite copper particles dispersed in a solvent.
溶媒の種類や、量は任意である。溶媒には、たとえば、プロピレングリコールや、グリセロールや、両者が混合されたものなどを使用することができる。 The type and amount of solvent are arbitrary. As the solvent, for example, propylene glycol, glycerol, or a mixture of both can be used.
（銅導電膜）
銅導電膜は、上述した銅インクを、基板などに所望のパターン形状に塗布したうえで、加熱して焼付けをおこなうことにより形成することができる。
(Copper conductive film)
The copper conductive film can be formed by applying the above-mentioned copper ink to a substrate or the like in a desired pattern shape, and then heating and baking the copper ink.
銅インクの焼付け温度は任意であるが、１５０℃程度の低温で焼付けることができる。銅インクの焼付け温度は、１５０℃よりも、大幅に低温にできる場合がある。 The baking temperature of the copper ink is arbitrary, but it can be baked at a low temperature of about 150 ° C. The baking temperature of the copper ink may be significantly lower than 150 ° C.
銅インクを焼付けることにより、銅微粒子が融解して銅ベース粒子と接合するとともに、銅微粒子どうしが接合して導電性パスが形成される。 By baking the copper ink, the copper fine particles are melted and bonded to the copper base particles, and the copper fine particles are bonded to each other to form a conductive path.
上述したとおり、銅インクに含まれる複合銅粒子において、銅ベース粒子の表面に配位された、炭素数が１以上、３以下の低級カルボン酸は、熱分解性に優れている。そのため、焼付け後に、銅ベース粒子の表面に、炭素などの残渣が残りにくい。したがって、本発明の銅インクを使用すれば、炭素などの残渣によって導電性パスの形成が妨げられにくく、シート抵抗率の低い銅導電膜を形成することができる。 As described above, among the composite copper particles contained in the copper ink, the lower carboxylic acid having 1 or more and 3 or less carbon atoms coordinated on the surface of the copper-based particles is excellent in thermal decomposability. Therefore, after baking, residues such as carbon are unlikely to remain on the surface of the copper-based particles. Therefore, when the copper ink of the present invention is used, the formation of a conductive path is less likely to be hindered by residues such as carbon, and a copper conductive film having a low sheet resistivity can be formed.
同じく上述したとおり、銅インクに含まれる複合銅粒子において、銅ベース粒子の表面に配位された、炭素数が１以上、３以下の低級カルボン酸は、主鎖が短く、銅微粒子の接近を妨げにくい。そのため、焼付けにより、銅ベース粒子と銅微粒子とが良好に接合する。したがって、本発明の銅インクを使用すれば、良好な導電性パスを形成することができ、シート抵抗率の低い銅導電膜を形成することができる。 Similarly, as described above, in the composite copper particles contained in the copper ink, the lower carboxylic acid having 1 or more and 3 or less carbon atoms coordinated on the surface of the copper base particles has a short main chain, and the copper fine particles approach each other. Hard to interfere. Therefore, the copper base particles and the copper fine particles are satisfactorily bonded by baking. Therefore, if the copper ink of the present invention is used, a good conductive path can be formed, and a copper conductive film having a low sheet resistivity can be formed.
以下に、実施例および比較例を示して、本発明を具体的に説明する。ただし、本発明は実施例には限定されない。 Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.
〈実施例１〉
（銅ベース粒子のギ酸による表面処理）
銅ベース粒子として、Ｄ５０が１μｍの銅粒子（高純度化学研究所製）を２ｇ用意した。銅ベース粒子の表面には、酸化防止などのために脂肪酸が配位されている。
<Example 1>
(Surface treatment of copper-based particles with formic acid)
As copper-based particles, 2 g of copper particles having a D50 of 1 μm (manufactured by the Institute of High Purity Chemistry) were prepared. Fatty acids are coordinated on the surface of the copper-based particles to prevent oxidation.
低級カルボン酸として、ギ酸（和光純薬工業製）を２０ｍＬ用意した。なお、ギ酸は、炭素数１のモノカルボン酸である。 As a lower carboxylic acid, 20 mL of formic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared. Formic acid is a monocarboxylic acid having 1 carbon atom.
以下の操作により、銅ベース粒子に対し、ギ酸による表面処理を施した。 The copper-based particles were surface-treated with formic acid by the following operations.
２ｇの銅ベース粒子を２０ｍＬのギ酸に浸漬させ、分散させた。 2 g of copper-based particles were immersed in 20 mL of formic acid and dispersed.
ギ酸に銅ベース粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離をおこない、銅ベース粒子が沈殿した溶液を得た。 A solution in which copper-based particles were dispersed in formic acid was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which copper-based particles were precipitated.
溶液を除去したうえ、沈殿した銅ベース粒子に２‐プロパノール（和光純薬工業製）を加え、銅ベース粒子を２‐プロパノールに分散させた。 After removing the solution, 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the precipitated copper-based particles, and the copper-based particles were dispersed in 2-propanol.
２‐プロパノールに銅ベース粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離をおこない、銅ベース粒子が沈殿した溶液を得た。遠心分離後には、銅が溶解したと見られる緑青色の溶液が見られた。この溶液の色が透明になるまで、２‐プロパノールを添加することによる遠心分離操作を複数回おこなった。 A solution in which copper-based particles were dispersed in 2-propanol was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which copper-based particles were precipitated. After centrifugation, a green-blue solution appeared in which copper appeared to have dissolved. Centrifugation by adding 2-propanol was performed multiple times until the color of this solution became transparent.
溶液の色が透明になった後、溶液を除去したうえで、銅ベース粒子を分離して回収した。 After the color of the solution became transparent, the solution was removed, and then the copper-based particles were separated and recovered.
表面処理前の銅ベース粒子の表面に酸化層が形成されていたとしても、得られた銅ベース粒子の表面からは、酸化層が除去されている。また、得られた銅ベース粒子の表面には、主鎖の長い脂肪酸に代わり、主鎖の短いギ酸が配位されている。 Even if an oxide layer is formed on the surface of the copper-based particles before the surface treatment, the oxide layer is removed from the surface of the obtained copper-based particles. Further, on the surface of the obtained copper-based particles, formic acid having a short main chain is coordinated instead of a fatty acid having a long main chain.
（酢酸銅溶液（銅イオンを含む金属塩溶液）の調製）
以下の操作により、銅イオンを含む金属塩溶液として、酢酸銅溶液を調整した。
(Preparation of copper acetate solution (metal salt solution containing copper ions))
A copper acetate solution was prepared as a metal salt solution containing copper ions by the following operations.
溶媒として、エチレングリコール（和光純薬工業製）を４２ｍＬ用意した。 As a solvent, 42 mL of ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared.
析出される銅微粒子の粒径を維持させるための保護剤として、イソプロパノールアミン（和光純薬工業製）を３．８５ｍＬ用意した。 3.85 mL of isopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared as a protective agent for maintaining the particle size of the precipitated copper fine particles.
エチレングリコール４２ｍＬに、イソプロパノールアミン３．８５ｍＬを溶解させ，混合溶液を作製した。 3.85 mL of isopropanolamine was dissolved in 42 mL of ethylene glycol to prepare a mixed solution.
混合溶液に、酢酸銅（II）（和光純薬工業製）０．９１ｇを溶解させ、０．１Ｍの酢酸銅溶液を調整した。溶液は、錯形成にともない、濃い青色に変化した。 0.91 g of copper (II) acetate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in the mixed solution to prepare a 0.1 M copper acetate solution. The solution turned dark blue with complex formation.
（ギ酸による表面処理をおこなった銅ベース粒子の酢酸銅溶液への添加）
酢酸銅溶液に、ギ酸による表面処理をおこなった銅ベース粒子１ｇを分散させた。銅ベース粒子の添加にともない、溶液は茶色に変化した。以下、この溶液を「原料溶液」と呼ぶ。
(Addition of copper-based particles surface-treated with formic acid to copper acetate solution)
1 g of copper-based particles surface-treated with formic acid was dispersed in a copper acetate solution. With the addition of copper-based particles, the solution turned brown. Hereinafter, this solution is referred to as a "raw material solution".
原料溶液を、スターラー回転数５００ｒｐｍで撹拌しながら、大気雰囲気下で、２５℃において、２４時間放置した。 The raw material solution was left at 25 ° C. for 24 hours in an atmospheric atmosphere while stirring at a stirrer rotation speed of 500 rpm.
（銅ベース粒子の表面への銅微粒子の析出）
還元剤として、銅モル換算で約１５倍量のヒドラジン一水和物（和光純薬工業製）２．４３ｍＬを用意した。
(Precipitation of copper fine particles on the surface of copper-based particles)
As a reducing agent, 2.43 mL of hydrazine monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared in an amount of about 15 times the amount in terms of copper molars.
２４時間放置した原料溶液に、ヒドラジン一水和物２．４３ｍＬを添加した。ヒドラジン一水和物の添加直後に、原料溶液から大量の気泡が発生して、瞬時に赤みのある黒色へと変化した。 2.43 mL of hydrazine monohydrate was added to the raw material solution left for 24 hours. Immediately after the addition of hydrazine monohydrate, a large amount of bubbles were generated from the raw material solution, and the color instantly changed to reddish black.
還元剤を添加した原料溶液を、スターラー回転数５００ｒｐｍで撹拌しながら、大気雰囲気下で、２４時間放置した。この反応の結果、ギ酸による表面処理をおこなった銅ベース粒子の表面に、銅微粒子が析出し、銅ベース粒子の表面に銅微粒子が被着した複合銅粒子が、溶液中で得られた。 The raw material solution to which the reducing agent was added was left to stand for 24 hours in an air atmosphere while stirring at a stirrer rotation speed of 500 rpm. As a result of this reaction, copper fine particles were precipitated on the surface of the copper-based particles surface-treated with formic acid, and composite copper particles in which the copper fine particles were adhered to the surface of the copper-based particles were obtained in the solution.
（複合銅粒子の分離、精製、回収）
以下の操作により、複合銅粒子が分散した溶液から、複合銅粒子を分離、精製、回収した。
(Separation, purification, recovery of composite copper particles)
The composite copper particles were separated, purified, and recovered from the solution in which the composite copper particles were dispersed by the following operations.
複合銅粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離を行ない、複合銅粒子が沈殿した溶液を得た。 The solution in which the composite copper particles were dispersed was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which the composite copper particles were precipitated.
溶液を除去したうえ、沈殿した複合銅粒子にジメチルアセトアミド（Ｎ、Ｎ‐ＤＭＡ；和光純薬工業製）を加え、複合銅粒子をジメチルアセトアミドに分散させた。 After removing the solution, dimethylacetamide (N, N-DMA; manufactured by Wako Pure Chemical Industries, Ltd.) was added to the precipitated composite copper particles, and the composite copper particles were dispersed in dimethylacetamide.
ジメチルアセトアミドに複合銅粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離をおこない、複合銅粒子が沈殿した溶液を得た。 The solution in which the composite copper particles were dispersed in dimethylacetamide was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which the composite copper particles were precipitated.
溶液を除去したうえ、沈殿した複合銅粒子にトルエン（和光純薬工業）を加え、複合銅粒子をトルエンに分散させた。 After removing the solution, toluene (Wako Pure Chemical Industries, Ltd.) was added to the precipitated composite copper particles, and the composite copper particles were dispersed in toluene.
トルエンに複合銅粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離をおこない、複合銅粒子が沈殿した溶液を得た。 The solution in which the composite copper particles were dispersed in toluene was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which the composite copper particles were precipitated.
溶液を除去したうえ、沈殿した複合銅粒子にヘキサン（和光純薬工業）を加え、複合銅粒子をヘキサンに分散させた。 After removing the solution, hexane (Wako Pure Chemical Industries, Ltd.) was added to the precipitated composite copper particles, and the composite copper particles were dispersed in hexane.
ヘキサンに複合銅粒子が分散した溶液に対して、１００００ｒｐｍ、５分間の条件で遠心分離をおこない、複合銅粒子が沈殿した溶液を得た。 The solution in which the composite copper particles were dispersed in hexane was centrifuged at 10000 rpm for 5 minutes to obtain a solution in which the composite copper particles were precipitated.
溶液を除去することによって、ギ酸による表面処理をおこなった銅ベース粒子の表面に銅微粒子が被着した複合銅粒子を、分離して回収した。 By removing the solution, the composite copper particles in which the copper fine particles were adhered to the surface of the copper base particles surface-treated with formic acid were separated and recovered.
図１に、ギ酸による表面処理をおこなった銅ベース粒子の表面に銅微粒子が析出した複合銅粒子を示す。 FIG. 1 shows composite copper particles in which copper fine particles are precipitated on the surface of copper-based particles that have been surface-treated with formic acid.
（銅インクの作製）
溶媒として、プロピレングリコール（和光純薬工業製）およびグリセロール（和光純薬工業製）を用意した。
(Copper ink production)
Propylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) and glycerol (manufactured by Wako Pure Chemical Industries, Ltd.) were prepared as solvents.
プロピレングリコールとグリセロールとを、５０体積比（１：１）で混合し、混合溶媒を作製した。 Propylene glycol and glycerol were mixed in a 50 volume ratio (1: 1) to prepare a mixed solvent.
混合溶媒に、上記の複合銅粒子を、固形分濃度が８０重量比となるように加えて、複合銅粒子が均一に分散した銅インクを得た。 The above-mentioned composite copper particles were added to the mixed solvent so that the solid content concentration was 80% by weight to obtain a copper ink in which the composite copper particles were uniformly dispersed.
（銅導電膜の形成）
銅インク（約８０重量比の複合銅粒子を含有）を、ポリイミド製の基板上に製膜し、塗膜を形成した。
(Formation of copper conductive film)
A copper ink (containing composite copper particles having a weight ratio of about 80) was formed on a polyimide substrate to form a coating film.
銅インクの塗膜が形成された基板を、窒素雰囲気下にて、１５０℃で、３０分間、低温加熱し、銅インクの焼付けをおこなった。この結果、銅微粒子が融解して、銅ベース粒子と強固に接合し、かつ、銅微粒子どうしが接合して導電性パスが形成され、クラックのない赤茶色の銅導電膜が形成された。図２に、銅微粒子が銅ベース粒子と接合するとともに、銅微粒子どうしが接合して導電性パスが形成された状態を示す。 The substrate on which the copper ink coating film was formed was heated at a low temperature of 150 ° C. for 30 minutes in a nitrogen atmosphere to bake the copper ink. As a result, the copper fine particles were melted and firmly bonded to the copper base particles, and the copper fine particles were bonded to each other to form a conductive path, and a crack-free reddish brown copper conductive film was formed. FIG. 2 shows a state in which the copper fine particles are bonded to the copper base particles and the copper fine particles are bonded to each other to form a conductive path.
（銅導電膜のシート抵抗率の測定）
三菱化学アナリティックロレスタを用いて、四探針法により、形成された銅導電膜の電気抵抗を測定した。実施例１にかかる銅導電膜のシート抵抗率は、１０ｍΩ／ｓｑであった。実施例１にかかる銅導電膜のシート抵抗率を、図３に示す。なお、実施例１にかかる銅導電膜のシート抵抗率の評価は、次に説明する比較例１にかかる銅導電膜のシート抵抗率の評価、および、比較例２にかかる銅導電膜のシート抵抗率の評価と合せて、後でおこなう。
(Measurement of sheet resistivity of copper conductive film)
Using a Mitsubishi Chemical Analytical Rolexta, the electrical resistance of the formed copper conductive film was measured by the four-probe method. The sheet resistivity of the copper conductive film according to Example 1 was 10 mΩ / sq. The sheet resistivity of the copper conductive film according to Example 1 is shown in FIG. The evaluation of the sheet resistivity of the copper conductive film according to Example 1 includes the evaluation of the sheet resistivity of the copper conductive film according to Comparative Example 1 described below and the sheet resistance of the copper conductive film according to Comparative Example 2. It will be done later together with the evaluation of the rate.
〈比較例１〉
（銅ベース粒子の用意）
銅ベース粒子として、Ｄ５０が１μｍの銅粒子を１ｇ用意した。銅ベース粒子の表面には、酸化防止などのために脂肪酸が配位されている。比較例１においては、銅ベース粒子の表面処理はおこなわない。
<Comparative example 1>
(Preparation of copper-based particles)
As copper-based particles, 1 g of copper particles having a D50 of 1 μm was prepared. Fatty acids are coordinated on the surface of the copper-based particles to prevent oxidation. In Comparative Example 1, the surface treatment of the copper-based particles is not performed.
（酢酸銅溶液（銅イオンを含む金属塩溶液）の調製）
実施例１と同様の方法によって、０．１Ｍの酢酸銅溶液を調整した。
(Preparation of copper acetate solution (metal salt solution containing copper ions))
A 0.1 M copper acetate solution was prepared by the same method as in Example 1.
（銅ベース粒子の酢酸銅溶液への添加）
実施例１と同様の方法によって、酢酸銅溶液に、表面処理をおこなっていない銅ベース粒子１ｇを分散させ「原料溶液」を作製した。そして、実施例１と同様に、原料溶液を、スターラー回転数５００ｒｐｍで撹拌しながら、大気雰囲気下で、２５℃において、２４時間放置した。
(Addition of copper-based particles to copper acetate solution)
By the same method as in Example 1, 1 g of unsurface-treated copper-based particles was dispersed in a copper acetate solution to prepare a “raw material solution”. Then, in the same manner as in Example 1, the raw material solution was left at 25 ° C. for 24 hours in an atmospheric atmosphere while stirring at a stirrer rotation speed of 500 rpm.
（銅ベース粒子の表面への銅微粒子の析出）
実施例１と同様に、還元剤を添加したうえ、銅ベース粒子が分散された原料溶液を、スターラー回転数５００ｒｐｍで撹拌しながら、大気雰囲気下で、２５℃において、２４時間放置した。この反応の結果、銅ベース粒子の表面に、銅微粒子が析出し、銅ベース粒子の表面に銅微粒子が被着した複合銅粒子が、溶液中で得られた。
(Precipitation of copper fine particles on the surface of copper-based particles)
In the same manner as in Example 1, the raw material solution in which the reducing agent was added and the copper-based particles were dispersed was left at 25 ° C. for 24 hours in an air atmosphere while stirring at a stirrer rotation speed of 500 rpm. As a result of this reaction, copper fine particles were precipitated on the surface of the copper-based particles, and composite copper particles in which the copper fine particles were adhered to the surface of the copper-based particles were obtained in the solution.
（複合銅粒子の分離、精製、回収）
実施例１と同様の方法によって、複合銅粒子が分散した溶液から、複合銅粒子を分離、精製、回収した。
(Separation, purification, recovery of composite copper particles)
The composite copper particles were separated, purified, and recovered from the solution in which the composite copper particles were dispersed by the same method as in Example 1.
（銅インクの作製）
実施例１と同様の方法によって、混合溶媒に、複合銅粒子を、固形分濃度が８０重量比となるように加えて、複合銅粒子が均一に分散した銅インクを得た。
(Copper ink production)
By the same method as in Example 1, composite copper particles were added to a mixed solvent so that the solid content concentration was 80% by weight to obtain a copper ink in which the composite copper particles were uniformly dispersed.
（銅導電膜の形成）
実施例１と同様の方法によって、ポリイミド製の基板上に、銅導電膜を形成した。
(Formation of copper conductive film)
A copper conductive film was formed on a polyimide substrate by the same method as in Example 1.
（銅導電膜のシート抵抗率の測定）
実施例１と同様の方法によって、銅導電膜の電気抵抗を測定した。銅ベース粒子の表面処理をおこなわなかった比較例１にかかる銅導電膜のシート抵抗率は、２５ｍΩ／ｓｑであった。比較例１にかかる銅導電膜のシート抵抗率を、図３に示す。
(Measurement of sheet resistivity of copper conductive film)
The electrical resistance of the copper conductive film was measured by the same method as in Example 1. The sheet resistivity of the copper conductive film according to Comparative Example 1 in which the surface treatment of the copper-based particles was not performed was 25 mΩ / sq. The sheet resistivity of the copper conductive film according to Comparative Example 1 is shown in FIG.
〈比較例２〉
（銅ベース粒子のヘキサン酸による表面処理）
銅ベース粒子として、Ｄ５０が１μｍの銅粒子（高純度化学研究所製）を２ｇ用意した。銅ベース粒子の表面には、酸化防止などのために脂肪酸が配位されている。
<Comparative example 2>
(Surface treatment of copper-based particles with caproic acid)
As copper-based particles, 2 g of copper particles having a D50 of 1 μm (manufactured by the Institute of High Purity Chemistry) were prepared. Fatty acids are coordinated on the surface of the copper-based particles to prevent oxidation.
ヘキサン酸（東京化成工業製）を２０ｍＬ用意した。なお、ヘキサン酸は、炭素数６のモノカルボン酸である。 20 mL of caproic acid (manufactured by Tokyo Chemical Industry) was prepared. Caproic acid is a monocarboxylic acid having 6 carbon atoms.
実施例１と同様の方法によって、銅ベース粒子に対し、ヘキサン酸による表面処理を施した。 The copper-based particles were surface-treated with caproic acid by the same method as in Example 1.
（酢酸銅溶液の調製、銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定）
実施例１と同様の方法によって、酢酸銅溶液の調製、ヘキサン酸による表面処理をおこなった銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定をおこなった。
(Preparation of copper acetate solution, addition of copper-based particles to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, separation, purification and recovery of composite copper particles, preparation of copper ink, formation of copper conductive film , Measurement of sheet resistance of copper conductive film)
Preparation of copper acetate solution, addition of copper-based particles surface-treated with hexanoic acid to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, composite copper particles by the same method as in Example 1. Separation, purification, recovery, preparation of copper ink, formation of copper conductive film, and measurement of sheet resistivity of copper conductive film were performed.
ヘキサン酸による銅ベース粒子の表面処理をおこなった比較例２にかかる銅導電膜のシート抵抗率は、１７ｍΩ／ｓｑであった。比較例１にかかる銅導電膜のシート抵抗率を、図３に示す。 The sheet resistivity of the copper conductive film according to Comparative Example 2 in which the surface treatment of the copper-based particles with caproic acid was performed was 17 mΩ / sq. The sheet resistivity of the copper conductive film according to Comparative Example 1 is shown in FIG.
＜実施例１と比較例１と比較例２の各シート抵抗率の比較＞
図３に示すように、ギ酸による銅ベース粒子の表面処理をおこなった実施例１にかかる銅導電膜のシート抵抗率は、１０ｍΩ／ｓｑであった。銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜のシート抵抗率は、２５ｍΩ／ｓｑであった。ヘキサン酸による銅ベース粒子の表面処理をおこなった比較例２にかかる銅導電膜のシート抵抗率は、１７ｍΩ／ｓｑであった。
<Comparison of each sheet resistivity of Example 1, Comparative Example 1 and Comparative Example 2>
As shown in FIG. 3, the sheet resistivity of the copper conductive film according to Example 1 in which the surface treatment of the copper-based particles with formic acid was performed was 10 mΩ / sq. The sheet resistivity of the copper conductive film according to Comparative Example 1 in which the surface treatment of the copper-based particles was not performed was 25 mΩ / sq. The sheet resistivity of the copper conductive film according to Comparative Example 2 in which the surface treatment of the copper-based particles with caproic acid was performed was 17 mΩ / sq.
銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜に対して、ギ酸による銅ベース粒子の表面処理をおこなった実施例１にかかる銅導電膜、および、ヘキサン酸による銅ベース粒子の表面処理をおこなった比較例２にかかる銅導電膜は、いずれも、シート抵抗率が改善した（シート抵抗率が小さくなった）。しかしながら、炭素数１のカルボン酸であるギ酸によって銅ベース粒子の表面処理をおこなった実施例１にかかる銅導電膜は、炭素数６のカルボン酸であるヘキサン酸によって銅ベース粒子の表面処理をおこなった比較例２にかかる銅導電膜に比べて、シート抵抗率が大きく改善した。この結果から、表面の少なくとも一部に、炭素数が１以上、３以下の低級カルボン酸が配位され銅ベース粒子に、低級カルボン酸を介して銅微粒子が被覆された本発明の複合銅粒子を、銅インクの銅粒子として使用することにより、銅インクを焼付けて形成した銅導電膜のシート抵抗を大きく改善できることが分かった。 In contrast to the copper conductive film according to Comparative Example 1 in which the surface treatment of the copper-based particles was not performed, the copper conductive film according to Example 1 in which the surface treatment of the copper-based particles was performed with formic acid and the copper-based particles using hexanoic acid. In all of the copper conductive films according to Comparative Example 2 which had undergone the surface treatment of (1), the sheet resistivity was improved (the sheet resistivity was reduced). However, in the copper conductive film according to Example 1 in which the surface treatment of the copper-based particles was performed with formic acid, which is a carboxylic acid having 1 carbon atoms, the surface treatment of the copper-based particles was performed by hexanoic acid, which is a carboxylic acid having 6 carbon atoms. Compared with the copper conductive film according to Comparative Example 2, the sheet resistivity was greatly improved. From this result, the composite copper particles of the present invention in which lower carboxylic acids having 1 or more and 3 or less carbon atoms are coordinated on at least a part of the surface and copper fine particles are coated on copper-based particles via lower carboxylic acids. It was found that the sheet resistance of the copper conductive film formed by baking the copper ink can be greatly improved by using the above as the copper particles of the copper ink.
〈実施例２〉
（銅ベース粒子の氷酢酸による表面処理）
銅ベース粒子として、Ｄ５０が１μｍの銅粒子（高純度化学研究所製）を２ｇ用意した。銅ベース粒子の表面には、酸化防止などのために脂肪酸が配位されている。
<Example 2>
(Surface treatment of copper-based particles with glacial acetic acid)
As copper-based particles, 2 g of copper particles having a D50 of 1 μm (manufactured by the Institute of High Purity Chemistry) were prepared. Fatty acids are coordinated on the surface of the copper-based particles to prevent oxidation.
氷酢酸（和光純薬工業製）を２０ｍＬ用意した。なお、氷酢酸は、炭素数２のモノカルボン酸である。 20 mL of glacial acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared. Glacial acetic acid is a monocarboxylic acid having 2 carbon atoms.
実施例１と同様の方法によって、銅ベース粒子に対し、氷酢酸による表面処理を施した。 The copper-based particles were surface-treated with glacial acetic acid by the same method as in Example 1.
（酢酸銅溶液の調製、銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定）
実施例１と同様の方法によって、酢酸銅溶液の調製、氷酢酸による表面処理をおこなった銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定をおこなった。
(Preparation of copper acetate solution, addition of copper-based particles to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, separation, purification and recovery of composite copper particles, preparation of copper ink, formation of copper conductive film , Measurement of sheet resistance of copper conductive film)
Preparation of copper acetate solution, addition of copper-based particles surface-treated with glacial acetic acid to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, composite copper particles by the same method as in Example 1. Separation, purification, recovery, preparation of copper ink, formation of copper conductive film, and measurement of sheet resistance of copper conductive film were performed.
氷酢酸による銅ベース粒子の表面処理をおこなった実施例２にかかる銅導電膜のシート抵抗率は、１０ｍΩ／ｓｑであった。実施例２にかかる銅導電膜のシート抵抗率を、図４に示す。なお、図４には、銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜のシート抵抗率を、併せて示している。 The sheet resistivity of the copper conductive film according to Example 2 in which the surface treatment of the copper-based particles with glacial acetic acid was performed was 10 mΩ / sq. The sheet resistivity of the copper conductive film according to Example 2 is shown in FIG. Note that FIG. 4 also shows the sheet resistivity of the copper conductive film according to Comparative Example 1 in which the surface treatment of the copper-based particles was not performed.
図４から分かるように、炭素数２のカルボン酸である氷酢酸によって銅ベース粒子の表面処理をおこなった実施例２にかかる銅導電膜は、銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜に比べて、シート抵抗率が大きく改善している。 As can be seen from FIG. 4, the copper conductive film according to Example 2 in which the surface treatment of the copper-based particles was performed with glacial acetic acid, which is a carboxylic acid having 2 carbon atoms, was compared with Comparative Example 1 in which the surface treatment of the copper-based particles was not performed. The sheet resistivity is greatly improved as compared with the copper conductive film applied to the above.
〈実施例３〉
（銅ベース粒子のプロピオン酸による表面処理）
銅ベース粒子として、Ｄ５０が１μｍの銅粒子（高純度化学研究所製）を２ｇ用意した。銅ベース粒子の表面には、酸化防止などのために脂肪酸が配位されている。
<Example 3>
(Surface treatment of copper-based particles with propionic acid)
As copper-based particles, 2 g of copper particles having a D50 of 1 μm (manufactured by the Institute of High Purity Chemistry) were prepared. Fatty acids are coordinated on the surface of the copper-based particles to prevent oxidation.
プロピオン酸（和光純薬工業製）を２０ｍＬ用意した。なお、プロピオン酸は、炭素数３のモノカルボン酸である。 20 mL of propionic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was prepared. Propionic acid is a monocarboxylic acid having 3 carbon atoms.
実施例１と同様の方法によって、銅ベース粒子に対し、プロピオン酸による表面処理を施した。 The copper-based particles were surface-treated with propionic acid by the same method as in Example 1.
（酢酸銅溶液の調製、銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定）
実施例１と同様の方法によって、酢酸銅溶液の調製、プロピオン酸による表面処理をおこなった銅ベース粒子の酢酸銅溶液への添加、銅ベース粒子の表面への銅微粒子の析出、複合銅粒子の分離、精製、回収、銅インクの作製、銅導電膜の形成、銅導電膜のシート抵抗率の測定をおこなった。
(Preparation of copper acetate solution, addition of copper-based particles to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, separation, purification and recovery of composite copper particles, preparation of copper ink, formation of copper conductive film , Measurement of sheet resistance of copper conductive film)
Preparation of copper acetate solution, addition of copper-based particles surface-treated with propionic acid to copper acetate solution, precipitation of copper fine particles on the surface of copper-based particles, composite copper particles by the same method as in Example 1. Separation, purification, recovery, preparation of copper ink, formation of copper conductive film, and measurement of sheet resistivity of copper conductive film were performed.
プロピオン酸による銅ベース粒子の表面処理をおこなった実施例３にかかる銅導電膜のシート抵抗率は、１２ｍΩ／ｓｑであった。実施例３にかかる銅導電膜のシート抵抗率を、図５に示す。なお、図５には、銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜のシート抵抗率を、併せて示している。 The sheet resistivity of the copper conductive film according to Example 3 in which the surface treatment of the copper-based particles with propionic acid was performed was 12 mΩ / sq. The sheet resistivity of the copper conductive film according to Example 3 is shown in FIG. Note that FIG. 5 also shows the sheet resistivity of the copper conductive film according to Comparative Example 1 in which the surface treatment of the copper-based particles was not performed.
図５から分かるように、炭素数２のカルボン酸であるプロピオン酸によって銅ベース粒子の表面処理をおこなった実施例３にかかる銅導電膜は、銅ベース粒子の表面処理をおこなっていない比較例１にかかる銅導電膜に比べて、シート抵抗率が大きく改善している。 As can be seen from FIG. 5, the copper conductive film according to Example 3 in which the surface treatment of the copper-based particles was performed with propionic acid, which is a carboxylic acid having 2 carbon atoms, was compared with Comparative Example 1 in which the surface treatment of the copper-based particles was not performed. The sheet resistivity is greatly improved as compared with the copper conductive film applied to the above.
以上の実施例１〜３、比較例１、２の結果から、次のことが分かった。 From the results of Examples 1 to 3 and Comparative Examples 1 and 2 described above, the following was found.
銅ベース粒子の表面に銅微粒子を析出させて銅複合粒子を作製するにあたり、予め、銅ベース粒子の表面を、炭素数１から３の低級カルボン酸で表面処理をすれば、当該銅複合粒子を含む銅インクを焼付けて銅導電膜を形成した場合に、シート抵抗率を大きく改善できることが分かった。 In order to prepare copper composite particles by precipitating copper fine particles on the surface of copper base particles, if the surface of the copper base particles is surface-treated with a lower carboxylic acid having 1 to 3 carbon atoms in advance, the copper composite particles can be obtained. It was found that the sheet resistivity can be greatly improved when the contained copper ink is baked to form a copper conductive film.
炭素数が１以上、３以下の低級カルボン酸は、脂肪酸などに比べて、主鎖が短く、沸点も低く、熱分解性に優れているため、銅インクの焼付け後に、銅ベース粒子の表面に炭素などの残渣が残りにくい。そのため、実施例１〜３では、炭素などの残渣によって導電性パスの形成が妨げられなかったため、銅導電膜のシート抵抗率が大きく改善したものと考えられる。 Lower carboxylic acids having 1 or more and 3 or less carbon atoms have a shorter main chain, a lower boiling point, and excellent thermal decomposability than fatty acids. Residues such as carbon are unlikely to remain. Therefore, in Examples 1 to 3, it is considered that the sheet resistivity of the copper conductive film was greatly improved because the formation of the conductive path was not hindered by the residue such as carbon.
また、炭素数が１以上、３以下の低級カルボン酸は、脂肪酸などに比べて、主鎖が短いため、銅微粒子の接近を妨げにくい。そのため、実施例１〜３では、焼付けにより、銅ベース粒子と銅微粒子とが良好に接合し、良好な導電性パスが形成され、銅導電膜のシート抵抗率が大きく改善したものと考えられる。 Further, a lower carboxylic acid having 1 or more and 3 or less carbon atoms has a shorter main chain than a fatty acid or the like, so that it is difficult to prevent the approach of copper fine particles. Therefore, in Examples 1 to 3, it is considered that the copper base particles and the copper fine particles were satisfactorily bonded by baking, a good conductive path was formed, and the sheet resistivity of the copper conductive film was greatly improved.
以上、本発明の実施形態および実施例について説明した。ただし、実施形態および実施例は、本発明の理解を容易にするためのものであり、本発明が実施形態および実施例の内容に限定されることはない。たとえば、銅イオンを含む金属塩溶液は、酢酸銅溶液には限定されず、他の種類のものを使用しても良い。また、金属塩溶液の溶媒や保護剤の種類も任意であり、他の種類のものを使用しても良い。また、還元剤もヒドラジン一水和物には限定されず、他の種類のものを使用しても良い。
The embodiments and examples of the present invention have been described above. However, the embodiments and examples are for facilitating the understanding of the present invention, and the present invention is not limited to the contents of the embodiments and examples. For example, the metal salt solution containing copper ions is not limited to the copper acetate solution, and other types may be used. Further, the type of the solvent and the protective agent of the metal salt solution is arbitrary, and other types may be used. Further, the reducing agent is not limited to hydrazine monohydrate, and other types may be used.
Claims (7)
前記銅ベース粒子の表面に被着された、前記銅ベース粒子よりも粒子径が小さい銅微粒子と、を備えた複合銅粒子であって、
前記銅ベース粒子は、表面の少なくとも一部に、炭素数が１以上、３以下の低級カルボン酸が配位され、
前記銅微粒子が、前記低級カルボン酸を介して前記銅ベース粒子に被着され、
前記低級カルボン酸が、ギ酸、氷酢酸、プロピオン酸のいずれか１つである、
複合銅粒子。 With copper-based particles,
A composite copper particle comprising copper fine particles having a particle diameter smaller than that of the copper-based particles, which is adhered to the surface of the copper-based particles.
In the copper-based particles, a lower carboxylic acid having 1 or more and 3 or less carbon atoms is coordinated on at least a part of the surface thereof.
The copper fine particles are adhered to the copper base particles via the lower carboxylic acid, and the copper fine particles are adhered to the copper base particles .
The lower carboxylic acid is any one of formic acid, glacial acetic acid, and propionic acid.
Composite copper particles.
前記銅微粒子の平均粒径が、０より大きく、１００ｎｍ以下である、請求項１に記載された複合銅粒子。 The average particle size of the copper-based particles is 0.1 μm or more and 10 μm or less.
The composite copper particles according to claim 1 , wherein the average particle size of the copper fine particles is larger than 0 and 100 nm or less.
溶媒と、を含んだ銅インク。 The composite copper particles according to claim 1 or 2,
Copper ink containing solvent.
前記ベース銅粒子を炭素数が１以上、３以下の低級カルボン酸に浸漬し、前記銅ベース粒子の表面の少なくとも一部に、前記低級カルボン酸を配位させる工程と、
銅イオンを含む金属塩溶液を用意する工程と、
前記金属塩溶液に、表面に前記低級カルボン酸が配位された前記銅ベース粒子を分散させる工程と、
前記銅ベース粒子が分散された前記金属塩溶液に還元剤を添加し、前記銅ベース粒子の表面に、前記低級カルボン酸を介して、前記銅ベース粒子よりも粒子径が小さい銅微粒子を析出させる工程と、を備えた複合銅粒子の製造方法。 The process of preparing the base copper particles and
A step of immersing the base copper particles in a lower carboxylic acid having 1 or more and 3 or less carbon atoms and coordinating the lower carboxylic acid on at least a part of the surface of the copper base particles.
The process of preparing a metal salt solution containing copper ions,
A step of dispersing the copper-based particles in which the lower carboxylic acid is coordinated on the surface in the metal salt solution, and
A reducing agent is added to the metal salt solution in which the copper-based particles are dispersed, and copper fine particles having a particle size smaller than that of the copper-based particles are precipitated on the surface of the copper-based particles via the lower carboxylic acid. A method for producing composite copper particles, which comprises a process.
前記銅微粒子の平均粒径が、０より大きく、１００ｎｍ以下である、請求項４ないし６
のいずれか１項に記載された複合銅粒子の製造方法。 The average particle size of the copper-based particles is 0.1 μm or more and 10 μm or less.
Claims 4 to 6 in which the average particle size of the copper fine particles is larger than 0 and 100 nm or less.
The method for producing composite copper particles according to any one of the above items.
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