JP5576318B2 - Copper particles - Google Patents
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- JP5576318B2 JP5576318B2 JP2011044538A JP2011044538A JP5576318B2 JP 5576318 B2 JP5576318 B2 JP 5576318B2 JP 2011044538 A JP2011044538 A JP 2011044538A JP 2011044538 A JP2011044538 A JP 2011044538A JP 5576318 B2 JP5576318 B2 JP 5576318B2
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims description 223
- 239000010949 copper Substances 0.000 title claims description 220
- 229910052802 copper Inorganic materials 0.000 title claims description 220
- 239000002245 particle Substances 0.000 title claims description 203
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 224
- 229910052759 nickel Inorganic materials 0.000 claims description 110
- 239000003638 chemical reducing agent Substances 0.000 claims description 71
- 239000002002 slurry Substances 0.000 claims description 48
- 229910017052 cobalt Inorganic materials 0.000 claims description 38
- 239000010941 cobalt Substances 0.000 claims description 38
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 38
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(I) oxide Inorganic materials [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 claims description 37
- 229940112669 cuprous oxide Drugs 0.000 claims description 37
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 claims description 37
- 238000004519 manufacturing process Methods 0.000 claims description 22
- 150000001875 compounds Chemical class 0.000 claims description 17
- 239000000470 constituent Substances 0.000 claims description 12
- 239000011164 primary particle Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 11
- 230000007423 decrease Effects 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- QUQFTIVBFKLPCL-UHFFFAOYSA-L copper;2-amino-3-[(2-amino-2-carboxylatoethyl)disulfanyl]propanoate Chemical compound [Cu+2].[O-]C(=O)C(N)CSSCC(N)C([O-])=O QUQFTIVBFKLPCL-UHFFFAOYSA-L 0.000 claims description 2
- 230000007704 transition Effects 0.000 description 42
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 24
- 229910052709 silver Inorganic materials 0.000 description 24
- 239000004332 silver Substances 0.000 description 24
- 230000003647 oxidation Effects 0.000 description 19
- 238000007254 oxidation reaction Methods 0.000 description 19
- 238000006722 reduction reaction Methods 0.000 description 18
- 230000009467 reduction Effects 0.000 description 15
- 239000002243 precursor Substances 0.000 description 13
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 12
- 239000007788 liquid Substances 0.000 description 11
- 229910001453 nickel ion Inorganic materials 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000009826 distribution Methods 0.000 description 7
- -1 lithium aluminum hydride Chemical compound 0.000 description 7
- 239000011162 core material Substances 0.000 description 6
- 239000007771 core particle Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000011521 glass Substances 0.000 description 5
- 238000013507 mapping Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine hydrate Chemical compound O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000002411 thermogravimetry Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910000365 copper sulfate Inorganic materials 0.000 description 3
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 3
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 3
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 3
- 239000012279 sodium borohydride Substances 0.000 description 3
- 229910000033 sodium borohydride Inorganic materials 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000011668 ascorbic acid Substances 0.000 description 2
- 229960005070 ascorbic acid Drugs 0.000 description 2
- 235000010323 ascorbic acid Nutrition 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910001429 cobalt ion Inorganic materials 0.000 description 2
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 238000007641 inkjet printing Methods 0.000 description 2
- 229910052809 inorganic oxide Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- UODXCYZDMHPIJE-UHFFFAOYSA-N menthanol Chemical compound CC1CCC(C(C)(C)O)CC1 UODXCYZDMHPIJE-UHFFFAOYSA-N 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 229940100890 silver compound Drugs 0.000 description 2
- 150000003379 silver compounds Chemical class 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 1
- JKFYKCYQEWQPTM-UHFFFAOYSA-N 2-azaniumyl-2-(4-fluorophenyl)acetate Chemical compound OC(=O)C(N)C1=CC=C(F)C=C1 JKFYKCYQEWQPTM-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- 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 1
- 239000012448 Lithium borohydride Substances 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- REYJJPSVUYRZGE-UHFFFAOYSA-N Octadecylamine Chemical compound CCCCCCCCCCCCCCCCCCN REYJJPSVUYRZGE-UHFFFAOYSA-N 0.000 description 1
- 241001596784 Pegasus Species 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 229910021612 Silver iodide Inorganic materials 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- GJYJYFHBOBUTBY-UHFFFAOYSA-N alpha-camphorene Chemical compound CC(C)=CCCC(=C)C1CCC(CCC=C(C)C)=CC1 GJYJYFHBOBUTBY-UHFFFAOYSA-N 0.000 description 1
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- RJTANRZEWTUVMA-UHFFFAOYSA-N boron;n-methylmethanamine Chemical compound [B].CNC RJTANRZEWTUVMA-UHFFFAOYSA-N 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- 229920003064 carboxyethyl cellulose Polymers 0.000 description 1
- 239000003985 ceramic capacitor Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- 229910021446 cobalt carbonate Inorganic materials 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- XXJWXESWEXIICW-UHFFFAOYSA-N diethylene glycol monoethyl ether Chemical compound CCOCCOCCO XXJWXESWEXIICW-UHFFFAOYSA-N 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009429 electrical wiring Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000004210 ether based solvent Substances 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000012280 lithium aluminium hydride Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 1
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 1
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 1
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- ACVYVLVWPXVTIT-UHFFFAOYSA-N phosphinic acid Chemical compound O[PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-N 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- CQLFBEKRDQMJLZ-UHFFFAOYSA-M silver acetate Chemical compound [Ag+].CC([O-])=O CQLFBEKRDQMJLZ-UHFFFAOYSA-M 0.000 description 1
- 229940071536 silver acetate Drugs 0.000 description 1
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 1
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 description 1
- 229940098221 silver cyanide Drugs 0.000 description 1
- 229940045105 silver iodide Drugs 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 229960001516 silver nitrate Drugs 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- BEOOHQFXGBMRKU-UHFFFAOYSA-N sodium cyanoborohydride Chemical compound [Na+].[B-]C#N BEOOHQFXGBMRKU-UHFFFAOYSA-N 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 150000003505 terpenes Chemical class 0.000 description 1
- 235000007586 terpenes Nutrition 0.000 description 1
- 229940116411 terpineol Drugs 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
- Conductive Materials (AREA)
- Non-Insulated Conductors (AREA)
Description
本発明は、ニッケル及びコバルトのうちの少なくとも一方を含有する銅粒子に関する。 The present invention relates to copper particles containing at least one of nickel and cobalt.
スクリーン印刷、ディスペンシング、インクジェット印刷等での微細配線形成において、印刷性や配線の緻密性を高める観点から、粒子径の小さい金属粒子が求められている。そのような金属粒子としては、主に、導電性が高い金属である銀や銅の粒子が用いられている。しかし銀は高価な材料であり、かつマイグレーションが起こりやすい問題がある。銅は表面活性が高く、容易に酸化する傾向を有するので、経時変化や脱媒工程中の酸化による高抵抗化が起こりやすい問題がある。 In the formation of fine wiring in screen printing, dispensing, ink jet printing, etc., metal particles having a small particle diameter are required from the viewpoint of improving printability and wiring density. As such metal particles, silver or copper particles, which are highly conductive metals, are mainly used. However, silver is an expensive material and has a problem that migration tends to occur. Since copper has a high surface activity and has a tendency to be easily oxidized, there is a problem in that high resistance is likely to occur due to aging and oxidation during the removal process.
そこでこの問題を解決するために、従来、銅粒子の表面を有機物や無機物酸化物で被覆したり、金属めっきしたりすることで、銅粒子に耐酸化性を付与することが行われている(特許文献1ないし5参照)。しかし有機物は高温で分解しやすいため、脱媒工程での耐酸化性を維持できないという問題を有する。無機物酸化物を被覆すれば、有機物を被覆した場合に比べて高温域まで耐酸化性が向上するが、電気抵抗値が高くなるという問題がある。また金属めっきは高価な試薬を使うだけでなく、廃液による環境負荷等の問題がある。 Therefore, in order to solve this problem, conventionally, the surface of the copper particle is coated with an organic substance or an inorganic oxide, or metal plating is performed to impart oxidation resistance to the copper particle ( (See Patent Documents 1 to 5). However, since organic substances are easily decomposed at a high temperature, there is a problem that the oxidation resistance in the removal process cannot be maintained. When the inorganic oxide is coated, the oxidation resistance is improved to a high temperature range as compared with the case where the organic material is coated, but there is a problem that the electric resistance value is increased. Metal plating not only uses expensive reagents, but also has problems such as environmental impact due to waste liquid.
本発明の課題は、前述した従来技術が有する種々の欠点を解消し得る銅粒子を提供することにある。 The subject of this invention is providing the copper particle which can eliminate the various fault which the prior art mentioned above has.
本発明は、ニッケル及びコバルトのうちの少なくとも一方を含み、ニッケル又はコバルトが粒子の表面域に偏在している銅粒子であって、
前記銅粒子の中心域は、主要構成元素が銅であり、
前記中心域から粒子表面に向かうに連れてニッケル又はコバルトの割合が漸増しているとともに銅の割合が漸減しており、
前記表面域は、銅と、ニッケル及びコバルトのうちの少なくとも一方とを含み、かつ銅の割合よりもニッケル及びコバルトの合計量の割合の方が高くなっており、
中心域においては、粒子の径方向での銅と、ニッケル及びコバルトの合計量との比率が略一定になっている銅粒子を提供するものである。
The present invention is a copper particle comprising at least one of nickel and cobalt, wherein nickel or cobalt is unevenly distributed in the surface area of the particle,
In the central region of the copper particles, the main constituent element is copper,
As the ratio of nickel or cobalt gradually increases from the central area toward the particle surface, the ratio of copper gradually decreases.
The surface area includes copper and at least one of nickel and cobalt, and the ratio of the total amount of nickel and cobalt is higher than the ratio of copper ,
In the central region, copper particles in which the ratio of copper in the radial direction of the particles to the total amount of nickel and cobalt is substantially constant are provided.
また本発明は、前記の銅粒子の好ましい製造方法として、
亜酸化銅粒子と、ニッケル及びコバルトのうちの少なくとも一方の水溶性化合物とを含む水性スラリーに、25℃での標準電極電位が0.34〜−0.36(E/V)である第1の還元剤を添加し、次いで、
25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する工程を有する銅粒子の製造方法を提供するものである。
In addition, the present invention provides a preferable method for producing the copper particles as described above.
A first electrode whose standard electrode potential at 25 ° C. is 0.34 to −0.36 (E / V) in an aqueous slurry containing cuprous oxide particles and a water-soluble compound of at least one of nickel and cobalt. Of reducing agent, and then
The present invention provides a method for producing copper particles, which comprises a step of adding a second reducing agent having a standard electrode potential at 25 ° C. of less than −0.36 (E / V) together with the first reducing agent. .
更に本発明は、前記の銅粒子の別の好ましい製造方法として、
亜酸化銅粒子を含む水性スラリーに、25℃での標準電極電位が0.34〜−0.36(E/V)である第1の還元剤を添加し、
ニッケル及びコバルトのうちの少なくとも一方の水溶性化合物を添加し、次いで、
25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する工程を有する銅粒子の製造方法を提供するものである。
Furthermore, the present invention provides another preferred method for producing the copper particles as described above.
A first reducing agent having a standard electrode potential of 0.34 to −0.36 (E / V) at 25 ° C. is added to the aqueous slurry containing cuprous oxide particles,
Adding at least one water-soluble compound of nickel and cobalt;
The present invention provides a method for producing copper particles, which comprises a step of adding a second reducing agent having a standard electrode potential at 25 ° C. of less than −0.36 (E / V) together with the first reducing agent. .
本発明によれば、耐酸化性が高く、かつ銅単体に近い導電性を有するニッケル又はコバルト含有の銅粒子が提供される。 According to the present invention, nickel or cobalt-containing copper particles having high oxidation resistance and conductivity close to that of simple copper are provided.
以下本発明を、その好ましい実施形態に基づき説明する。本発明の銅粒子は、銅を主要構成元素として含み、添加元素としてニッケル及びコバルトのうちの少なくとも一方を少量含有するものである。ニッケル又はコバルトは粒子の表面域に偏在している。以下の説明においては、ニッケル及びコバルトを総称して「ニッケル等」ともいう。「ニッケル等」というときには文脈に応じてニッケル及びコバルトの双方を意味する場合と、ニッケル又はコバルトを択一的に意味する場合とがある。 Hereinafter, the present invention will be described based on preferred embodiments thereof. The copper particles of the present invention contain copper as a main constituent element and contain a small amount of at least one of nickel and cobalt as an additive element. Nickel or cobalt is unevenly distributed in the surface area of the particles. In the following description, nickel and cobalt are collectively referred to as “nickel etc.”. “Nickel etc.” may mean both nickel and cobalt depending on the context, and may alternatively mean nickel or cobalt.
本発明の銅粒子は、その径方向に沿っていくつかの部位に大別される。該部位は、中心域及び表面域である。中心域とは、銅粒子の最も内側に位置している部位のことである。表面域とは、銅粒子の最表面を含み、かつ該最表面から所定の深さにわたる部位のことである。また本発明の銅粒子は、その用途によっては、中心域と表面域との間に位置する遷移域を有していてもよい。図1には、本発明の銅粒子における銅及びニッケル等の径方向の分布と、中心域A、遷移域B及び表面域Cとの関係の一例が示されている。同図に示す銅粒子は、ニッケル等としてニッケルを含有するものである。以下、これら各域について説明する。 The copper particles of the present invention are roughly divided into several parts along the radial direction. The part is a central region and a surface region. The central region is a portion located on the innermost side of the copper particles. The surface area is a portion including the outermost surface of the copper particles and extending from the outermost surface to a predetermined depth. Moreover, the copper particle of this invention may have the transition area located between a center area | region and a surface area depending on the use. FIG. 1 shows an example of the relationship between the radial distribution of copper, nickel, and the like in the copper particles of the present invention, and the central area A, transition area B, and surface area C. The copper particles shown in the figure contain nickel as nickel or the like. Hereinafter, each of these areas will be described.
本発明の銅粒子においては、主要構成元素である銅は、該銅粒子の主として中心域Aに多量に存在している。このことによって本発明の銅粒子は、ニッケル等を含有するものでありながら、全体としては銅単体に近い性質を発現するものとなる。銅粒子の中心域は、銅のみから構成されているか、又は銅を主要構成元素として含み、かつ少量構成元素としてニッケル等を含んでいる部位である。主要構成元素とは、当該元素の存在割合が60atm%以上、特に70atm%以上である元素のことをいう。一方、少量構成元素とは、当該元素の存在割合が40atm%以下、特に30atm%以下である元素のことをいう。 In the copper particles of the present invention, copper, which is a main constituent element, is present in a large amount mainly in the central region A of the copper particles. As a result, the copper particles of the present invention, which contain nickel or the like, exhibit properties close to those of copper alone as a whole. The central region of the copper particles is composed of only copper or contains copper as a main constituent element and nickel or the like as a small constituent element. The main constituent element refers to an element having a presence ratio of the element of 60 atm% or more, particularly 70 atm% or more. On the other hand, the minor constituent element refers to an element in which the presence ratio of the element is 40 atm% or less, particularly 30 atm% or less.
中心域Aが銅のみから構成されている場合、該中心域Aとは、本発明の銅粒子における内部に位置し、かつ銅のみからなる部位のことである。中心域Aが銅を主要構成元素として含み、かつ少量構成元素としてニッケル等を含んでいる場合、該中心域Aとは、銅粒子における内部に位置し、かつ銅粒子の径方向での銅とニッケル等との比率が略一定になっている部位のことである。 When the central area A is composed only of copper, the central area A is a portion that is located inside the copper particles of the present invention and is composed only of copper. When the central area A contains copper as a main constituent element and nickel or the like as a minor constituent element, the central area A is located inside the copper particles and the copper in the radial direction of the copper particles It is a part where the ratio to nickel or the like is substantially constant.
中心域Aに少量構成元素であるニッケル及びコバルトのうちの少なくとも一方が含まれている場合、これらの元素は、いずれか一方のみを用いてもよく、両方を併用してもよい。中心域Aが銅及びニッケル等を含有する場合、該中心域Aは銅とニッケル等との合金から構成されることが好ましい。 When the central region A contains at least one of nickel and cobalt, which are small constituent elements, only one of these elements may be used, or both may be used in combination. When the central area A contains copper and nickel, the central area A is preferably composed of an alloy of copper and nickel.
銅に加えてニッケル等を含有する中心域Aを有する銅粒子は、銅のみからなる中心域Aを有する銅粒子に比べて、中心域Aと、後述する遷移域Bや表面域Cとが剥離しづらくなるという利点がある。 Copper particles having a central region A containing nickel or the like in addition to copper are separated from a central region A and a transition region B or a surface region C described later, compared to a copper particle having a central region A made of only copper. There is an advantage that it becomes difficult to do.
中心域Aが、ニッケル等を含むか否かにかかわらず、該中心域Aにおける銅の割合は、銅とニッケル等との合計量に対して80atm%以上であることが好ましく、90atm%以上であることが更に好ましい。一方、ニッケル及びコバルトの合計量の割合は、銅とニッケル等との合計量に対して20atm%以下であることが好ましく、10atm%以下であることが更に好ましい。 Regardless of whether or not the central region A contains nickel or the like, the ratio of copper in the central region A is preferably 80 atm% or more with respect to the total amount of copper and nickel, and is 90 atm% or more. More preferably it is. On the other hand, the ratio of the total amount of nickel and cobalt is preferably 20 atm% or less, and more preferably 10 atm% or less with respect to the total amount of copper and nickel.
中心域Aが、銅に加えてニッケル等を含んでいる場合、銅とニッケル及びコバルトの合計量との比率がほぼ一定になっている該中心域Aにおける銅の割合は、銅とニッケル等との合計量に対して80〜99atm%であることが好ましく、90〜99atm%であることが更に好ましい。一方、ニッケル及びコバルトの合計量の割合は、銅とニッケル等との合計量に対して1〜20atm%であることが好ましく、1〜10atm%であることが更に好ましい。中心域における銅及びニッケル等の割合がこの範囲内であることによって、本発明の銅粒子は、ニッケル等を含有するものでありながら、全体としては銅単体に近い導電性を発現するものとなる。 When the central area A contains nickel or the like in addition to copper, the ratio of copper to the total amount of nickel and cobalt is substantially constant. The ratio of copper in the central area A is copper and nickel, etc. It is preferable that it is 80-99 atm% with respect to the total amount of, and it is still more preferable that it is 90-99 atm%. On the other hand, the ratio of the total amount of nickel and cobalt is preferably 1 to 20 atm% and more preferably 1 to 10 atm% with respect to the total amount of copper and nickel. When the ratio of copper, nickel, and the like in the central region is within this range, the copper particles of the present invention, as a whole, exhibit conductivity close to that of simple copper, while containing nickel and the like. .
中心域Aが、銅に加えてニッケル等を含んでいる場合、銅とニッケル及びコバルトの合計量との比率がほぼ一定になっている該中心域Aの直径は、銅粒子の一次粒子径の45〜90%であることが好ましく、48〜75%であることが更に好ましい。中心域Aが銅のみからなる場合にも、銅粒子の一次粒子径に対する該中心域Aの直径はこの範囲内であることが好ましい。銅粒子の一次粒子径に対する該中心域Aの直径がこの範囲内であることによって、本発明の銅粒子は、銅よりも導電性の低い金属であるニッケル等を含有するものでありながら、全体としては銅単体に近い導電性を発現するものとなる。 When the central area A contains nickel or the like in addition to copper, the ratio of the total amount of copper and nickel and cobalt is substantially constant. The diameter of the central area A is the primary particle diameter of the copper particles. It is preferably 45 to 90%, and more preferably 48 to 75%. Even when the central area A is made of only copper, the diameter of the central area A with respect to the primary particle diameter of the copper particles is preferably within this range. When the diameter of the central region A with respect to the primary particle diameter of the copper particles is within this range, the copper particles of the present invention contain nickel or the like, which is a metal having a conductivity lower than that of copper. As such, it exhibits conductivity close to that of copper alone.
ニッケル等は、本発明の銅粒子の表面近傍、すなわち表面域C及び遷移域Bに偏在している。表面域C及び遷移域Bに偏在しているニッケル等は、本発明の銅粒子の耐酸化性を高める目的で用いられている。詳細には、ニッケル等は、銅よりも耐酸化性の高い元素である。このような元素が本発明の銅粒子の表面近傍に偏在していることによって、本発明の銅粒子の耐酸化性が高められる。そして、該銅粒子の中心域Aは、先に述べたとおり銅を主要構成元素として含んでいるので、本発明の銅粒子は、銅の有する高い導電性が維持される。これらの結果、本発明の銅粒子は、銅単体に近い導電性を有するものでありながら、銅単体よりも高い耐酸化性を有するものとなる。 Nickel and the like are unevenly distributed near the surface of the copper particles of the present invention, that is, in the surface region C and the transition region B. Nickel and the like that are unevenly distributed in the surface region C and the transition region B are used for the purpose of improving the oxidation resistance of the copper particles of the present invention. Specifically, nickel or the like is an element having higher oxidation resistance than copper. Such elements are unevenly distributed near the surface of the copper particles of the present invention, whereby the oxidation resistance of the copper particles of the present invention is enhanced. And since the center area | region A of this copper particle contains copper as a main structural element as stated above, the high electroconductivity which copper has of the copper particle of this invention is maintained. As a result, the copper particles of the present invention have higher oxidation resistance than copper alone, while having conductivity close to that of copper alone.
ニッケル等が偏在している遷移域Bは、必要に応じて形成される部位である。遷移域Bは、中心域Aと表面域Cとの間に位置する部位であり、一定の厚みを有する略球殻をなしている。遷移域Bには、ニッケル等に加えて銅が含まれている。ニッケル等と銅とは好ましくは合金を形成している。遷移域Bにおいては銅の割合がニッケル等の割合以上になっている。また、遷移域Bにおいては粒子表面に向かうに連れてニッケル等の割合が漸増している。これとともに遷移域Bにおいては、粒子表面に向かうに連れて銅の割合が漸減している。このように遷移域Bにおいては、銅及びニッケル等の割合が連続的に変化しており、銅のみの領域やニッケルのみの領域は存在していない。 The transition region B where nickel or the like is unevenly distributed is a part formed as necessary. The transition region B is a portion located between the central region A and the surface region C, and forms a substantially spherical shell having a certain thickness. The transition region B contains copper in addition to nickel and the like. Nickel or the like and copper preferably form an alloy. In the transition zone B, the proportion of copper is equal to or greater than the proportion of nickel or the like. In the transition region B, the proportion of nickel or the like gradually increases toward the particle surface. At the same time, in the transition region B, the ratio of copper gradually decreases toward the particle surface. Thus, in the transition area B, the ratio of copper, nickel, etc. changes continuously, and there is no copper-only area or nickel-only area.
遷移域Bにおける中心域A寄りの部位においては、粒子内部に向かうに連れてニッケル等の存在割合が漸減しており、遷移域Bと中心域Aとの境界を挟んで、遷移域Bと中心域Aとでニッケル等の存在割合が連続的に変化している。銅に関しても同様に、遷移域Bにおける中心域A寄りの部位においては、粒子内部に向かうに連れて銅の存在割合が漸増しており、遷移域と中心域との境界を挟んで、遷移域Bと中心域Aとで銅の存在割合が連続的に変化している。これによって、遷移域Bと中心域Aとの一体性が高まり、両域の境界における剥離が起こりづらくなる。 In the region close to the central region A in the transition region B, the abundance ratio of nickel and the like gradually decreases toward the inside of the particle, and the transition region B and the center are located across the boundary between the transition region B and the central region A. The existence ratio of nickel or the like continuously changes in the area A. Similarly for copper, in the region close to the central region A in the transition region B, the proportion of copper gradually increases toward the inside of the particle, and the transition region is sandwiched between the transition region and the central region. The existence ratio of copper continuously changes between B and the central area A. Thereby, the integrity of the transition area B and the central area A is increased, and separation at the boundary between the two areas is less likely to occur.
一方、遷移域Bにおける表面域C寄りの部位においては、粒子表面に向かうに連れてニッケル等の存在割合が漸増しており、遷移域Bと表面域Cとの境界を挟んで、遷移域Bと表面域Cとでニッケル等の存在割合が連続的に変化している。銅に関しても同様に、遷移域Bにおける表面域C寄りの部位においては、粒子表面に向かうに連れて銅の存在割合が漸減しており、遷移域Bと表面域Cとの境界を挟んで、遷移域Bと表面域Cとで銅の存在割合が連続的に変化している。これによって、遷移域Bと表面域Cとの一体性が高まり、両域の境界における剥離が起こりづらくなる。 On the other hand, in the region close to the surface region C in the transition region B, the abundance ratio of nickel and the like gradually increases toward the particle surface, and the transition region B sandwiches the boundary between the transition region B and the surface region C. And the surface region C, the abundance ratio of nickel or the like continuously changes. Similarly for copper, in the region close to the surface region C in the transition region B, the proportion of copper gradually decreases toward the particle surface, with the boundary between the transition region B and the surface region C sandwiched between them, The proportion of copper present in the transition zone B and the surface zone C changes continuously. As a result, the integrity of the transition region B and the surface region C is increased, and separation at the boundary between both regions is less likely to occur.
このように、遷移域Bにおいて、銅及びニッケル等の割合が連続的に変化していることで、中心域Aと表面域Cとが遷移域Bを介して連続体となるので、表面域Cの剥離が効果的に防止される。これとは対照的に、例えば銅の芯材粒子の表面にニッケル等をめっきによって被覆したり、銅の芯材粒子の表面に酸化物の微粒子を付着させたりすると、芯材粒子と、めっき部分又は酸化物の微粒子との剥離が起こりやすい。遷移域Bの機能を効果的に発現させる観点から、該遷移域Bの厚みを2倍した値は、本発明の銅粒子の一次粒子径の9.9〜54.9%であることが好ましく、24.5〜51.5%であることが更に好ましい。 As described above, since the ratio of copper, nickel, and the like continuously changes in the transition region B, the central region A and the surface region C become a continuous body via the transition region B. Is effectively prevented from peeling. In contrast, for example, when the surface of the copper core particle is coated with nickel or the like, or the oxide fine particles are attached to the surface of the copper core particle, the core particle and the plated portion Alternatively, the oxide is easily separated from the fine particles. From the viewpoint of effectively expressing the function of the transition region B, the value obtained by doubling the thickness of the transition region B is preferably 9.9 to 54.9% of the primary particle diameter of the copper particles of the present invention. More preferably, it is 24.5 to 51.5%.
次に表面域Cについて説明する。表面域Cとは、先に述べた遷移域Bよりも粒子の外側に位置し、かつ本発明の銅粒子の表面を含む領域である。表面域Cは一定の厚みを有する略球殻をなしている。表面域Cは、遷移域Bと同様にニッケル等及び銅を含んでいる。本発明の銅粒子の耐酸化性を高める観点からは、表面域はニッケル等のみで構成されることが有利であるが、ニッケル等は銅に比べて導電性が低いことから、表面域Cをニッケル等のみで構成すると、本発明の銅粒子の導電性を、銅単体に近づけることが容易でなくなる。そこで、表面域Cにも銅を含有させることで、導電性低下の防止を図っている。尤も表面域Cにおける銅の割合はニッケル等の割合よりも低くなっている。つまり、表面域Cにおいては、銅の割合よりもニッケル等の割合の方が高くなっている。こうすることで、耐酸化性を損なうことなく、導電性を維持することができる。 Next, the surface area C will be described. The surface area C is an area that is located outside the transition area B and includes the surface of the copper particles of the present invention. The surface area C forms a substantially spherical shell having a certain thickness. Similar to the transition region B, the surface region C contains nickel or the like and copper. From the viewpoint of enhancing the oxidation resistance of the copper particles of the present invention, it is advantageous that the surface area is composed only of nickel or the like. However, since nickel or the like has lower conductivity than copper, the surface area C is reduced. If it consists only of nickel etc., it will become difficult to make the electroconductivity of the copper particle of this invention close to a copper simple substance. Therefore, the surface region C is also made to contain copper, thereby preventing the decrease in conductivity. However, the proportion of copper in the surface area C is lower than the proportion of nickel or the like. That is, in the surface area C, the ratio of nickel or the like is higher than the ratio of copper. By doing so, the conductivity can be maintained without impairing the oxidation resistance.
表面域Cにおいては、銅とニッケル等が共存していることは上述のとおりであるところ、該表面域Cにおいて、銅とニッケル等とは合金を形成していることが好ましい。また、表面域Cにおいては、該表面域Cの厚み方向において、銅及びニッケルの存在割合の傾斜は、遷移域におけるそれらの存在割合の傾斜よりも小さくなっている。 In the surface region C, copper and nickel coexist as described above, and in the surface region C, it is preferable that copper and nickel form an alloy. Further, in the surface region C, in the thickness direction of the surface region C, the inclination of the existence ratio of copper and nickel is smaller than the inclination of the existence ratio in the transition region.
表面域Cはその厚みを2倍した値が、銅粒子の一次粒子径の0.1〜45.1%であることが好ましく、0.5〜27.5%であることが更に好ましい。銅粒子の一次粒子径に対する表面域Cの厚みがこの範囲内であることによって、本発明の銅粒子は、耐酸化性と導電性の双方が両立したものとなる。 In the surface area C, the value obtained by doubling the thickness is preferably 0.1 to 45.1%, more preferably 0.5 to 27.5% of the primary particle diameter of the copper particles. When the thickness of the surface area C with respect to the primary particle diameter of the copper particles is within this range, the copper particles of the present invention have both oxidation resistance and conductivity.
表面域Cにおける銅の割合は、銅とニッケル等との合計量に対して1〜49atm%であることが好ましく、2〜30atm%であることが更に好ましい。一方、ニッケル及びコバルトの合計量の割合は、銅とニッケル等との合計量に対して51〜99atm%であることが好ましく、70〜98atm%であることが更に好ましい。表面域Cにおける銅及びニッケル等の割合がこの範囲内であることによって、本発明の銅粒子は、ニッケル等を含有するものでありながら、全体としては銅単体に近い導電性を発現するものとなる。 The proportion of copper in the surface region C is preferably 1 to 49 atm%, more preferably 2 to 30 atm%, based on the total amount of copper and nickel. On the other hand, the ratio of the total amount of nickel and cobalt is preferably 51 to 99 atm% and more preferably 70 to 98 atm% with respect to the total amount of copper and nickel. When the ratio of copper and nickel in the surface area C is within this range, the copper particles of the present invention contain nickel and the like, and as a whole, develop conductivity close to that of copper alone. Become.
前記の表面域C及び遷移域Bの厚みや表面域C及び遷移域Bでの銅及びニッケル等の割合、並びに先に述べた中心域Aの直径や該中心域Aでの銅及びニッケル等の割合は、FIBを用いて銅粒子の断面のサンプルを作製し、該断面をSEM−STEM−EDXを用いて元素分析することで求めることができる。 The thickness of the surface area C and the transition area B, the ratio of copper and nickel in the surface area C and the transition area B, the diameter of the central area A described above, the copper and nickel in the central area A, etc. The ratio can be obtained by preparing a sample of a cross section of a copper particle using FIB and conducting elemental analysis of the cross section using SEM-STEM-EDX.
本発明の銅粒子全体に占めるニッケル及びコバルトの合計量の割合は、導電性と耐酸化性とのバランスの点から、10〜40atm%であることが好ましく、10〜30atm%であることが更に好ましい。この割合は、本発明の銅粒子を硝酸や硫酸等の溶媒に全溶解させて溶液を調製し、その溶液をICP発光分光分析装置によって分析することによって測定することができる。 The ratio of the total amount of nickel and cobalt in the entire copper particles of the present invention is preferably 10 to 40 atm%, more preferably 10 to 30 atm%, from the viewpoint of the balance between conductivity and oxidation resistance. preferable. This ratio can be measured by preparing a solution by completely dissolving the copper particles of the present invention in a solvent such as nitric acid or sulfuric acid, and analyzing the solution with an ICP emission spectrometer.
本発明の銅粒子は、その用途に応じて粒径を適宜調整できる。本発明の銅粒子を、例えばスクリーン印刷、ディスペンシング及びインクジェット印刷等の手段で微細電気配線形成に用いる場合には、一次粒子径を50〜2000nmに設定することが好ましく、200〜1000nmに設定することが更に好ましい。銅粒子の一次粒子径は、例えば画像解析式粒度分布測定ソフトウェアMacView(株式会社マウンテック製)によって測定することができる。 The particle size of the copper particles of the present invention can be appropriately adjusted according to the application. When the copper particles of the present invention are used for forming fine electrical wiring by means such as screen printing, dispensing and ink jet printing, the primary particle diameter is preferably set to 50 to 2000 nm, and set to 200 to 1000 nm. More preferably. The primary particle diameter of the copper particles can be measured by, for example, image analysis type particle size distribution measurement software MacView (manufactured by Mountec Co., Ltd.).
本発明の銅粒子は、その用途に応じて形状を適宜調整できる。典型的には等方形状、例えば球状の形状を採用することができる。 The shape of the copper particles of the present invention can be appropriately adjusted according to the application. Typically, an isotropic shape such as a spherical shape can be employed.
本発明の銅粒子は例えば導電性ペーストの原料として用いることができる。この導電性ペーストは、本発明の銅粒子と、有機ビヒクルと、ガラスフリットとを含有するものである。この有機ビヒクルは、樹脂成分と溶剤とを含む。樹脂成分としては、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。溶剤としては、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。ガラスフリットとしては、ホウケイ酸ガラス、ホウケイ酸バリウムガラス、ホウケイ酸亜鉛ガラス等が挙げられる。導電性ペーストにおける銅粒子の割合は例えば36〜97.5質量%とすることが好ましい。ガラスフリットの割合は例えば1.5〜14質量%とすることが好ましい。有機ビヒクルの割合は例えば1〜50質量%とすることが好ましい。 The copper particles of the present invention can be used as a raw material for conductive paste, for example. This conductive paste contains the copper particles of the present invention, an organic vehicle, and glass frit. This organic vehicle includes a resin component and a solvent. Examples of the resin component include acrylic resin, epoxy resin, ethyl cellulose, carboxyethyl cellulose, and the like. Examples of the solvent include terpene solvents such as terpineol and dihydroterpineol, and ether solvents such as ethyl carbitol and butyl carbitol. Examples of the glass frit include borosilicate glass, borosilicate barium glass, and borosilicate zinc glass. The ratio of the copper particles in the conductive paste is preferably, for example, 36 to 97.5% by mass. The ratio of the glass frit is preferably 1.5 to 14% by mass, for example. The ratio of the organic vehicle is preferably 1 to 50% by mass, for example.
このようにして得られた導電性ペーストは、例えば、プリント配線板の回路形成、セラミックコンデンサの外部電極等の電気的導通確保、EMI対策のために好適に使用される。 The conductive paste thus obtained is preferably used for, for example, circuit formation of a printed wiring board, ensuring electrical continuity of an external electrode of a ceramic capacitor, and measures against EMI.
本発明においては、これまで説明してきた銅粒子の導電性を一層高める用い方を採用することができる。この目的のために、本発明によれば、上述の銅粒子を芯材粒子として用い、該芯材粒子の表面を銀の層で被覆してなる銀被覆銅粒子も提供される。この銀被覆銅粒子における芯材粒子は、上述の銅粒子そのものである。芯材粒子の表面を被覆する銀の層は、該芯材粒子の表面を連続して被覆していてもよく、あるいは不連続に(例えば島状に)被覆していてもよい。銀の層が芯材粒子の表面を連続して被覆している場合には、銀被覆銅粒子の表面には、芯材粒子の表面が露出していない。銀の層が芯材粒子の表面を不連続に被覆している場合には、銀被覆銅粒子の表面には、芯材粒子の表面の一部が露出しており、例えば特性X線を用いた元素マッピングによって銅及びニッケル等が検出される。銀は銅よりも導電性の高い金属なので、銅粒子の表面を銀の層で被覆することで、導電性が一層高まる。また銀は銅よりも酸化されづらい元素なので、耐酸化性も高まる。しかも銀は、銅粒子の表面を被覆するに足る量を用いればよいので、銅よりも高価な金属である銀を用いても経済的に不利とはならない。この銀被覆銅粒子も、先に述べた銅粒子と同様に導電性ペーストの原料として用いることができる。つまり、この銀被覆銅粒子を用いて、該銀被覆銅粒子を含む導電性ペーストを調製することができる。 In this invention, the usage which raises the electroconductivity of the copper particle demonstrated so far can be employ | adopted. For this purpose, according to the present invention, there is also provided silver-coated copper particles obtained by using the above-mentioned copper particles as core material particles and coating the surface of the core material particles with a silver layer. The core particles in the silver-coated copper particles are the above-described copper particles themselves. The silver layer covering the surface of the core material particles may continuously cover the surface of the core material particles, or may be discontinuously (for example, in an island shape). In the case where the silver layer continuously covers the surface of the core material particles, the surface of the core material particles is not exposed on the surface of the silver-coated copper particles. When the silver layer covers the surface of the core particle discontinuously, a part of the surface of the core particle is exposed on the surface of the silver-coated copper particle, for example, using characteristic X-rays. Copper, nickel and the like are detected by the element mapping. Since silver is a metal having a higher conductivity than copper, the conductivity is further increased by covering the surface of the copper particles with a silver layer. Moreover, since silver is an element which is harder to oxidize than copper, oxidation resistance also increases. And since silver should just use the quantity sufficient to coat | cover the surface of a copper particle, even if it uses silver which is a metal more expensive than copper, it will not become economically disadvantageous. The silver-coated copper particles can also be used as a raw material for the conductive paste in the same manner as the copper particles described above. That is, a conductive paste containing the silver-coated copper particles can be prepared using the silver-coated copper particles.
次に、本発明の銅粒子の好適な製造方法について説明する。本発明の銅粒子は、主として、以下に述べる製造方法1及び製造方法2に従い好適に製造することができる。 Next, the suitable manufacturing method of the copper particle of this invention is demonstrated. The copper particles of the present invention can be suitably produced mainly in accordance with production method 1 and production method 2 described below.
〔製造方法1〕
本製造方法においては、(1−1)亜酸化銅粒子と、ニッケル及びコバルトのうちの少なくとも一方の水溶性化合物とを含む水性スラリーに、25℃での標準電極電位が0.34〜−0.36(E/V)である第1の還元剤を添加し、次いで、(1−2)25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する。以下、本製造方法について詳細に説明する。
[Production Method 1]
In this production method, (1-1) an aqueous slurry containing cuprous oxide particles and at least one water-soluble compound of nickel and cobalt has a standard electrode potential of 0.34 to −0 at 25 ° C. A first reducing agent that is .36 (E / V) is added, and then (1-2) a second reducing agent whose standard electrode potential at 25 ° C. is less than −0.36 (E / V) Together with the first reducing agent. Hereinafter, this production method will be described in detail.
(1−1)の工程においては、亜酸化銅粒子と、ニッケル及びコバルトのうちの少なくとも一方の水溶性化合物とを用意する。亜酸化銅粒子は、その粒径に制限はなく、該亜酸化銅粒子から銅が首尾よく還元する程度の粒径を有していればよい。ニッケル等の水溶性化合物としては、ニッケルに関しては例えば硫酸ニッケル、塩化ニッケル、硝酸ニッケル、炭酸ニッケル、酢酸ニッケル、水酸化ニッケル等が挙げられ、コバルトに関しては例えば、塩化コバルト、硫酸コバルト、炭酸コバルト、酢酸コバルト等が挙げられる。 In the step (1-1), cuprous oxide particles and at least one water-soluble compound of nickel and cobalt are prepared. The particle size of the cuprous oxide particles is not limited as long as it has a particle size such that copper can be successfully reduced from the cuprous oxide particles. Examples of water-soluble compounds such as nickel include nickel sulfate, nickel chloride, nickel nitrate, nickel carbonate, nickel acetate, nickel hydroxide and the like, and cobalt includes, for example, cobalt chloride, cobalt sulfate, cobalt carbonate, Examples include cobalt acetate.
水性スラリー中における亜酸化銅粒子の濃度は、還元を首尾よく行う観点から、0.1〜20質量%とすることが好ましく、1〜10質量%とすることが更に好ましい。ニッケル等の水溶性化合物の濃度は、目的とする銅粒子に含まれるニッケル等の割合に応じて、亜酸化銅粒子の濃度との関係で決定される。 The concentration of the cuprous oxide particles in the aqueous slurry is preferably 0.1 to 20% by mass, and more preferably 1 to 10% by mass from the viewpoint of successful reduction. The concentration of the water-soluble compound such as nickel is determined in relation to the concentration of the cuprous oxide particles according to the ratio of nickel or the like contained in the target copper particles.
亜酸化銅粒子及びニッケル等の水溶性化合物を水と混合して水性スラリーが得られたら、これに第1の還元剤を添加する。第1の還元剤は、先に述べたとおり25℃での標準電極電位が0.34〜−0.36(E/V)であるものである。このような標準電極電位を有する還元剤を用いることで、亜酸化銅を還元させることができ、かつニッケルイオン又はコバルトイオンの還元を可能な限り抑えることができる。そのような還元剤としては、例えばヒドラジン、グルコース、アスコルビン酸、ホルムアルデヒド、アルコールなどが挙げられる。これらの還元剤は、単独で用いてもよく、あるいは2種以上を組み合わせて用いてもよい。水性スラリーに第1の還元剤を添加するに際しては、該還元剤が所望の還元力を発現するようにするために、水性スラリー中の温度等を調整することが好ましい。例えば第1の還元剤としてヒドラジンを用いる場合には、水性スラリーを50〜80℃に加熱することが好ましい。第1の還元剤の添加は一括添加でもよく、あるいは一定時間にわたる逐次添加でもよい。還元のコントロールのしやすさの点からは、逐次添加を行うことが有利である。 When an aqueous slurry is obtained by mixing water-soluble compounds such as cuprous oxide particles and nickel with water, a first reducing agent is added thereto. As described above, the first reducing agent has a standard electrode potential at 25 ° C. of 0.34 to −0.36 (E / V). By using a reducing agent having such a standard electrode potential, cuprous oxide can be reduced, and reduction of nickel ions or cobalt ions can be suppressed as much as possible. Examples of such a reducing agent include hydrazine, glucose, ascorbic acid, formaldehyde, alcohol, and the like. These reducing agents may be used alone or in combination of two or more. When adding the first reducing agent to the aqueous slurry, it is preferable to adjust the temperature or the like in the aqueous slurry so that the reducing agent exhibits a desired reducing power. For example, when hydrazine is used as the first reducing agent, the aqueous slurry is preferably heated to 50 to 80 ° C. The first reducing agent may be added all at once, or may be added sequentially over a certain period of time. From the viewpoint of ease of control of reduction, it is advantageous to perform sequential addition.
第1の還元剤の添加量は、該還元剤の添加完了後の水性スラリー中に、未還元の亜酸化銅粒子が残存する量とする。こうすることで、後述する(1−2)の工程においても、亜酸化銅粒子の還元が生じるからである。 The first reducing agent is added in such an amount that unreduced cuprous oxide particles remain in the aqueous slurry after completion of the addition of the reducing agent. This is because reduction of the cuprous oxide particles occurs also in the step (1-2) described later.
第1の還元剤の添加が完了した時点では、亜酸化銅粒子の還元によって生成した銅の粒子(この粒子を、目的とする銅粒子と区別する目的で「前駆体粒子」という。)が水性スラリー中に含まれている。また、未還元の亜酸化銅粒子が残存している。第1の還元剤は消費されて、水性スラリー中には実質的に存在していない。更に、第1の還元剤によるニッケルイオン等の還元はほとんど生じておらず、イオンの状態で水性スラリー中に存在している。尤も、一部のニッケルイオン等が第1の還元剤によって還元されることがあり、その場合には、亜酸化銅粒子の還元によって生成した前駆体粒子中に、ニッケル等が銅との合金を形成して少量含有された状態になっている。この状態の前駆体粒子におけるニッケル等の分布は該粒子の径方向において略均一になっている。前駆体粒子は、目的とする銅粒子における中心域Aにほぼ対応する。 When the addition of the first reducing agent is completed, the copper particles produced by the reduction of the cuprous oxide particles (referred to as “precursor particles” for the purpose of distinguishing these particles from the intended copper particles) are aqueous. Contained in the slurry. Further, unreduced cuprous oxide particles remain. The first reducing agent is consumed and is substantially absent from the aqueous slurry. Furthermore, the reduction | restoration of nickel ion etc. by the 1st reducing agent has hardly arisen, and exists in the aqueous slurry in the state of an ion. However, some nickel ions and the like may be reduced by the first reducing agent. In that case, nickel or the like may form an alloy with copper in the precursor particles generated by reduction of the cuprous oxide particles. It is formed and contained in a small amount. The distribution of nickel or the like in the precursor particles in this state is substantially uniform in the radial direction of the particles. The precursor particles substantially correspond to the central region A in the target copper particles.
第1の還元剤の添加が完了したら、次いで前記の(1−2)の工程を行う。本工程においては、還元力の異なる2種の還元剤を用いる。これら2種の還元剤としては、先に述べた第1の還元剤と、25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤とを用いる。本工程で用いる第1の還元剤は、先に述べた(1−1)の工程で用いた第1の還元剤と同種でもよく、あるいは異種でもよい。第2の還元剤を用いることで、亜酸化銅並びにニッケルイオン及びコバルトイオンを還元させることができる。そのような第2の還元剤としては、例えば水素化ホウ素ナトリウム、シアノ水素化ホウ素ナトリウム、水素化ホウ素リチウム、水素化ホウ素亜鉛、水素化アルミニウムリチウム、水素化ビスアルミニウムナトリウムなどが挙げられる。これら第2の還元剤は、単独で用いてもよく、あるいは2種以上を組み合わせて用いてもよい。第1の還元剤についても同様である。 When the addition of the first reducing agent is completed, the above step (1-2) is then performed. In this step, two reducing agents having different reducing powers are used. As these two reducing agents, the first reducing agent described above and the second reducing agent having a standard electrode potential at 25 ° C. of less than −0.36 (E / V) are used. The first reducing agent used in this step may be the same as or different from the first reducing agent used in the step (1-1) described above. By using the second reducing agent, cuprous oxide, nickel ions, and cobalt ions can be reduced. Examples of such second reducing agent include sodium borohydride, sodium cyanoborohydride, lithium borohydride, zinc borohydride, lithium aluminum hydride, sodium bisaluminum hydride, and the like. These second reducing agents may be used alone or in combination of two or more. The same applies to the first reducing agent.
第1の還元剤と第2の還元剤の添加は、どちらか一方を先行して添加し、他方を後から添加してもよく、あるいは両還元剤を同時に添加してもよい。いずれの場合であっても、第1及び第2の還元剤の添加は一括添加でもよく、あるいは一定時間にわたる逐次添加でもよい。還元のコントロールのしやすさの点からは、逐次添加を行うことが有利である。 As for the addition of the first reducing agent and the second reducing agent, either one may be added in advance, and the other may be added later, or both reducing agents may be added simultaneously. In either case, the first and second reducing agents may be added all at once, or may be added sequentially over a certain period of time. From the viewpoint of ease of control of reduction, it is advantageous to perform sequential addition.
第1及び第2の還元剤を水性スラリーに添加するに際しては、これらの還元剤が所望の還元力を発現するように、水性スラリー中の温度等を調整することが好ましい。例えば第1の還元剤としてヒドラジンを用い、かつ第2の還元剤として水素化ホウ素ナトリウムを用いる場合には、水性スラリーを50〜80℃に加熱することが好ましい。 When the first and second reducing agents are added to the aqueous slurry, it is preferable to adjust the temperature and the like in the aqueous slurry so that these reducing agents exhibit a desired reducing power. For example, when hydrazine is used as the first reducing agent and sodium borohydride is used as the second reducing agent, the aqueous slurry is preferably heated to 50 to 80 ° C.
第1及び第2の還元剤の添加によって、前駆体粒子の表面に、銅及びニッケル等が析出する。これによって目的とする銅粒子における遷移域B及び表面域Cが形成される。遷移域B及び表面域Cを首尾よく形成するためには、上述した水性スラリーの温度等を調整することが必要であるほかに、第1の還元剤と第2の還元剤との使用比率を適切に調整することも必要である。この観点から、第1の還元剤と第2の還元剤との使用比率(質量比)を、第1の還元剤:第2の還元剤=500:1〜50:1とすることが好ましい。こうすることで、本工程において、亜酸化銅粒子の還元の程度が時間の経過とともに徐々に低下し、それとは対照的にニッケルイオン等の還元の程度が徐々に高まる。その結果、前駆体粒子の表面に遷移域Bが形成され、引き続き表面域Cが形成される。 By adding the first and second reducing agents, copper, nickel and the like are deposited on the surface of the precursor particles. Thereby, the transition region B and the surface region C in the target copper particle are formed. In order to successfully form the transition zone B and the surface zone C, it is necessary to adjust the temperature and the like of the aqueous slurry described above, and the use ratio of the first reducing agent and the second reducing agent is It is also necessary to adjust appropriately. From this point of view, it is preferable that the use ratio (mass ratio) of the first reducing agent and the second reducing agent is first reducing agent: second reducing agent = 500: 1 to 50: 1. By doing so, in this step, the degree of reduction of the cuprous oxide particles gradually decreases with time, and in contrast, the degree of reduction of nickel ions and the like gradually increases. As a result, a transition region B is formed on the surface of the precursor particles, and a surface region C is subsequently formed.
このようにして目的とする銅粒子が得られる。この銅粒子の中心域における銅及びニッケル等の径方向の分布は、第1の還元剤の種類によっては、先に述べた図1に示すとおり、中心域が銅を主要構成元素とし、かつニッケル等が少量含有されたものとなる。もちろん、第1の還元剤の種類によっては、中心域が実質的に銅のみからなるものを得ることもできる。「実質的に」とは、意図せず不可避的に銅以外の元素が混入することを許容する趣旨である。 In this way, the intended copper particles are obtained. Depending on the type of the first reducing agent, the radial distribution of copper, nickel, etc. in the central region of the copper particles is as shown in FIG. Etc. are contained in a small amount. Of course, depending on the type of the first reducing agent, it is also possible to obtain a material whose central region is substantially made only of copper. “Substantially” means that elements other than copper are inevitably mixed in unintentionally.
〔製造方法2〕
本製造方法においては、(2−1)亜酸化銅粒子を含む水性スラリーに、25℃での標準電極電位が0.34〜−0.36(E/V)である第1の還元剤を添加し、(2−2)該水性スラリーにニッケル及びコバルトのうちの少なくとも一方の水溶性化合物を添加し、次いで、(2−3)25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する。
[Production Method 2]
In this production method, (2-1) a first reducing agent having a standard electrode potential at 25 ° C. of 0.34 to −0.36 (E / V) is added to an aqueous slurry containing cuprous oxide particles. And (2-2) at least one water-soluble compound of nickel and cobalt is added to the aqueous slurry, and then (2-3) a standard electrode potential at −25 ° C. is −0.36 (E / A second reducing agent that is less than V) is added along with the first reducing agent.
(2−1)の工程において用いられる亜酸化銅粒子及び第1の還元剤としては、製造方法1の工程(1−1)で用いたものと同様のものを用いることができる。水性スラリー中の亜酸化銅粒子の濃度や、水性スラリーの温度も工程(1−1)と同様とすることができる。また、水性スラリーに添加する第1の還元剤の量は、工程(1−1)と同様に、該還元剤の添加完了後の水性スラリー中に、未還元の亜酸化銅粒子が残存する量とする。 As a cuprous oxide particle and a 1st reducing agent used in the process of (2-1), the thing similar to what was used at the process (1-1) of the manufacturing method 1 can be used. The concentration of the cuprous oxide particles in the aqueous slurry and the temperature of the aqueous slurry can be the same as in step (1-1). The amount of the first reducing agent added to the aqueous slurry is the amount of unreduced cuprous oxide particles remaining in the aqueous slurry after completion of the addition of the reducing agent, as in step (1-1). And
(2−1)の工程において生成する前駆体粒子は、目的とする銅粒子における中心域にほぼ対応する。この前駆体粒子は、先に述べた製造方法1の(1−1)の工程で生成する前駆体粒子と異なり、該粒子中にニッケル等を含有することはない。前駆体粒子の生成時においては、反応系内にニッケルイオン等は存在していないからである。 The precursor particles generated in the step (2-1) substantially correspond to the central region of the target copper particles. Unlike the precursor particle produced | generated at the process of (1-1) of the manufacturing method 1 mentioned previously, this precursor particle | grain does not contain nickel etc. in this particle | grain. This is because nickel ions or the like do not exist in the reaction system when the precursor particles are generated.
第1の還元剤の添加が完了した時点では、亜酸化銅粒子の還元によって生成した前駆体粒子が水性スラリー中に含まれている。また、未還元の亜酸化銅粒子が残存している。第1の還元剤は消費されて、水性スラリー中には実質的に存在していない。この状態下に、(2−2)の工程を行い、水性スラリー中にニッケル及びコバルトのうちの少なくとも一方の水溶性化合物を添加する。該水溶性化合物としては、製造方法1の工程(1−1)で用いたものと同様のものを用いることができる。また、水性スラリー中における該水溶性化合物の濃度は、目的とする銅粒子に含まれるニッケル等の割合に応じて、仕込みの亜酸化銅粒子の濃度との関係で決定される。水性スラリー中にニッケル等の水溶性化合物を添加した時点では還元反応はほとんど生じず、該スラリー中には、前駆体粒子、亜酸化銅粒子及びニッケルイオン等が存在している。 When the addition of the first reducing agent is completed, precursor particles generated by reduction of the cuprous oxide particles are contained in the aqueous slurry. Further, unreduced cuprous oxide particles remain. The first reducing agent is consumed and is substantially absent from the aqueous slurry. Under this state, the step (2-2) is performed, and at least one water-soluble compound of nickel and cobalt is added to the aqueous slurry. As the water-soluble compound, the same compounds as those used in the step (1-1) of production method 1 can be used. The concentration of the water-soluble compound in the aqueous slurry is determined in relation to the concentration of the charged cuprous oxide particles according to the ratio of nickel or the like contained in the target copper particles. When a water-soluble compound such as nickel is added to the aqueous slurry, the reduction reaction hardly occurs, and the precursor particles, cuprous oxide particles, nickel ions, and the like are present in the slurry.
次いで(2−3)の工程を行う。本工程では、製造方法1の工程(1−2)と同様の操作を行う。したがって、本工程の詳細については、製造方法1の工程(1−2)に関する説明が適宜適用される。 Next, the step (2-3) is performed. In this step, the same operation as in step (1-2) of manufacturing method 1 is performed. Therefore, for the details of this step, the description regarding the step (1-2) of the manufacturing method 1 is appropriately applied.
製造方法2を採用すると、中心域が実質的に銅のみからなる銅粒子を容易に得ることができる。「実質的に」とは、意図せず不可避的に銅以外の元素が混入することを許容する趣旨である。 When the production method 2 is adopted, copper particles whose center region is substantially made of only copper can be easily obtained. “Substantially” means that elements other than copper are inevitably mixed in unintentionally.
製造方法1及び2のいずれを採用した場合であっても、その後に付加的な工程を更に行うことで、先に述べた銀被覆銅粒子を得ることができる。この付加的な工程としては、製造方法1又は2で得られた銅粒子及び銀の水溶性化合物を含む水性スラリーに、銀イオンの還元剤を添加する工程が挙げられる。この工程に用いられる銀の水溶性化合物としては、例えば硝酸銀、酢酸銀、ヨウ化銀、塩化銀、酸化銀、臭化銀、シアン化銀等が挙げられる。これらの化合物は、単独で又は2種以上を組み合わせて用いることができる。また、銀イオンの還元剤としては、例えば次亜リン酸、ジメチルアミンボラン、ヒドラジン、アスコルビン酸、ホルムアルデヒド、グルコース、アルコール等、銀の標準電極が0.799V以下の物質の溶液が挙げられる。これらの還元剤は、単独で又は2種以上を組み合わせて用いることができる。 Even if it employs any one of production methods 1 and 2, the silver-coated copper particles described above can be obtained by further performing additional steps thereafter. As this additional step, there is a step of adding a silver ion reducing agent to the aqueous slurry containing the copper particles and the silver water-soluble compound obtained in the production method 1 or 2. Examples of the water-soluble silver compound used in this step include silver nitrate, silver acetate, silver iodide, silver chloride, silver oxide, silver bromide, and silver cyanide. These compounds can be used alone or in combination of two or more. Examples of the silver ion reducing agent include solutions of substances having a standard silver electrode of 0.799 V or less, such as hypophosphorous acid, dimethylamine borane, hydrazine, ascorbic acid, formaldehyde, glucose, alcohol, and the like. These reducing agents can be used alone or in combination of two or more.
還元剤による銀イオンの還元工程においては、水性スラリーに含まれる銀の水溶性化合物の濃度や、水性スラリーに添加する還元剤の種類及び/又は量を適宜調整することで、銅粒子の表面に析出する銀の析出状態をコントロールすることができる。つまり、銅粒子の表面を連続して被覆する銀の層が形成されるように還元を行うこともでき、あるいは銅粒子の表面を不連続に(例えば島状に)被覆する銀の層が形成されるように還元を行うこともできる。そのような還元の条件は、当該技術分野における当業者の知識の範囲内であり、特に説明するまでもない。 In the silver ion reduction step with the reducing agent, the concentration of the water-soluble silver compound contained in the aqueous slurry and the type and / or amount of the reducing agent added to the aqueous slurry are adjusted as appropriate to the surface of the copper particles. It is possible to control the deposition state of the deposited silver. In other words, the reduction can be performed so that a silver layer continuously covering the surface of the copper particles is formed, or a silver layer covering the surface of the copper particles discontinuously (for example, in an island shape) is formed. Reduction can also be performed. Such reduction conditions are within the knowledge of those skilled in the art and need not be specifically described.
以上、本発明をその好ましい実施形態に基づき説明したが、本発明は前記の実施形態に制限されない。例えば前記の説明は、銅粒子の中心域と表面域との間に遷移域が存在する好ましい実施形態に基づくものであったが、銅粒子の用途によっては、遷移域を形成しなくてもよい。 As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, the above description is based on a preferred embodiment in which a transition region exists between the central region and the surface region of the copper particles, but depending on the use of the copper particles, the transition region may not be formed. .
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。 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.
〔実施例1〕
純水0.73リットルに、40.4gの亜酸化銅粒子及び67.1gの硫酸ニッケルを加えて70℃で混合して水性スラリーを得た。この温度条件下に、42.4gのヒドラジン(25℃における標準電極電位:0.11E/V)を30分間にわたり逐次添加した。これによって、亜酸化銅粒子に由来する前駆体粒子が水性スラリー中に生成した。また、水性スラリーには、未還元の亜酸化銅粒子が残存し、かつニッケルイオンが存在していた。
[Example 1]
40.4 g of cuprous oxide particles and 67.1 g of nickel sulfate were added to 0.73 liter of pure water and mixed at 70 ° C. to obtain an aqueous slurry. Under this temperature condition, 42.4 g of hydrazine (standard electrode potential at 25 ° C .: 0.11 E / V) was sequentially added over 30 minutes. Thereby, precursor particles derived from cuprous oxide particles were produced in the aqueous slurry. In the aqueous slurry, unreduced cuprous oxide particles remained and nickel ions were present.
次に、水性スラリーの温度を上述の条件に調整した状態で、57.5gのヒドラジンと、0.1gの水素化ホウ素ナトリウム(25℃における標準電極電位:−1.241E/V)とを同時に、かつ1分間にわたり逐次添加した。このようにして、目的とする銅粒子を得た。 Next, 57.5 g of hydrazine and 0.1 g of sodium borohydride (standard electrode potential at −25 ° C .: −1.241 E / V) are simultaneously applied with the temperature of the aqueous slurry adjusted to the above-described conditions. And sequentially added over 1 minute. In this way, target copper particles were obtained.
〔実施例2〕
実施例1において、硫酸ニッケルの使用量を22.3gに減量した。これ以外は実施例1と同様にして銅粒子を得た。
[Example 2]
In Example 1, the amount of nickel sulfate used was reduced to 22.3 g. Except this, it carried out similarly to Example 1, and obtained the copper particle.
〔比較例1〕
本比較例は銅のみからなる粒子の例である。この粒子は、特開2009−74152号公報の実施例1に準じて製造した。まず純水6.5Lに硫酸銅6000gを投入して撹拌し、その後、液温を50℃に保持しつつ、硫酸銅水溶液の液量が9リットルとなるように、更に水を添加して、濃度を調整した。当該硫酸銅水溶液に、アンモニア水溶液(濃度25質量%)2537ミリリットルを30分で添加して中和し、銅塩化合物スラリーを得た。そして、銅塩化合物スラリーを30分静置して熟成させた。ここまでは銅塩化合物スラリーの液温を50℃に保持したが、熟成後は液温を45℃に調整した。次に、銅塩化合物スラリーの銅濃度が2.0mol/リットルとなるように水を添加して液量を調整した。この銅塩化合物スラリーをpH6.3、液温50℃の条件に保ち、ここに、ヒドラジン1水和物450gとpH調整剤としてのアンモニア水溶液(濃度25質量%)591mリットルとを30分間かけて連続添加し、亜酸化銅スラリーとした。そして、還元反応を完全に行うため、更に30分間撹拌を続けた。その後、リパルプ洗浄のため、亜酸化銅スラリーに純水を加えて18リットルに液量調整した後、静置して亜酸化銅粒子を沈殿させ、静置後の上澄液を14リットル抜く操作を、pHが4.7になるまで繰り返した。そして、温めた純水8リットルを加えて全液量を12リットルにし、液温を45℃に維持して、銅濃度を2.0mol/リットルに調整し、これを洗浄亜酸化銅スラリーとした。銅濃度調整後の洗浄亜酸化銅スラリーに、次亜リン酸アンモニウム3.02gを添加し、5分間撹拌した。再び、洗浄亜酸化銅スラリーの銅濃度が2.0mol/リットルとなるように水を添加して液量を調整した。この洗浄亜酸化銅スラリーに、ヒドラジン一水和物1200gを30分間で添加した。次に、更に15分間撹拌を行い、還元反応を完全に行わせ銅粉を還元析出させた。析出した銅粒子を濾過して採取した。そして、洗浄後、当該銅粉に、オクタデシルアミン1.5gを溶解させたメタノール溶液5リットルに入れ有機表面処理を施し、濾別分離後、70℃、5時間の加熱乾燥を行い、更に解砕処理を施して銅粒子を得た。
[Comparative Example 1]
This comparative example is an example of particles made only of copper. These particles were produced according to Example 1 of JP2009-74152A. First, 6000 g of copper sulfate was added to 6.5 L of pure water and stirred, and then water was further added so that the liquid volume of the copper sulfate aqueous solution was 9 liters while maintaining the liquid temperature at 50 ° C. The concentration was adjusted. To the copper sulfate aqueous solution, 2537 ml of an aqueous ammonia solution (concentration 25% by mass) was added in 30 minutes for neutralization to obtain a copper salt compound slurry. The copper salt compound slurry was allowed to stand for 30 minutes for aging. Up to this point, the liquid temperature of the copper salt compound slurry was maintained at 50 ° C., but after aging, the liquid temperature was adjusted to 45 ° C. Next, the amount of liquid was adjusted by adding water so that the copper concentration of the copper salt compound slurry was 2.0 mol / liter. The copper salt compound slurry was maintained at a pH of 6.3 and a liquid temperature of 50 ° C., and 450 g of hydrazine monohydrate and 591 ml of an aqueous ammonia solution (concentration 25% by mass) as a pH adjuster were taken over 30 minutes. Continuously added to obtain a cuprous oxide slurry. Then, in order to complete the reduction reaction, stirring was continued for another 30 minutes. Thereafter, pure water is added to the cuprous oxide slurry to adjust the volume to 18 liters for repulp washing, and then left to stand to precipitate cuprous oxide particles, and 14 liters of the supernatant liquid after standing is drained. Was repeated until the pH was 4.7. Then, 8 liters of warm pure water was added to make the total liquid volume 12 liters, the liquid temperature was maintained at 45 ° C., the copper concentration was adjusted to 2.0 mol / liter, and this was used as a washed cuprous oxide slurry. . To the washed cuprous oxide slurry after adjusting the copper concentration, 3.02 g of ammonium hypophosphite was added and stirred for 5 minutes. Again, the amount of liquid was adjusted by adding water so that the copper concentration of the washed cuprous oxide slurry was 2.0 mol / liter. To this washed cuprous oxide slurry, 1200 g of hydrazine monohydrate was added over 30 minutes. Next, the mixture was further stirred for 15 minutes to complete the reduction reaction and to reduce and precipitate the copper powder. The precipitated copper particles were collected by filtration. After washing, the copper powder is put into 5 liters of a methanol solution in which 1.5 g of octadecylamine is dissolved, subjected to organic surface treatment, separated by filtration, dried by heating at 70 ° C. for 5 hours, and further crushed. Treatment was performed to obtain copper particles.
〔比較例2〕
本比較例は、銅のみからなる粒子の表面に二酸化ケイ素からなる微粒子を付着させてなる粒子の例である。この粒子は、特許文献1(特開2004−84069号公報)の〔0037〕〜〔0040〕に準じて製造した。具体的には銅粒子1kgと酸化ケイ素粒子0.05kgとを、ハイブリタイザーを用いて、回転数6000rpmで、5分間のメカノケミカルな固着処理を行い、酸化ケイ素コート銅粒子を製造した。
[Comparative Example 2]
This comparative example is an example of particles obtained by attaching fine particles made of silicon dioxide to the surface of particles made only of copper. These particles were produced according to [0037] to [0040] of Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-84069). Specifically, 1 kg of copper particles and 0.05 kg of silicon oxide particles were subjected to mechanochemical fixing treatment at a rotation speed of 6000 rpm for 5 minutes using a hybridizer to produce silicon oxide-coated copper particles.
〔評価〕
実施例及び比較例で得られた粒子について、その一次粒子径、及び粒子中に占めるニッケルの割合を、上述の方法で測定した。また、粒子断面における径方向での銅及びニッケルの元素マッピングから中心域の直径並びに遷移域及び表面域の厚みを測定した。更に、熱重量測定(TG)によって粒子の耐酸化性を以下の手順で評価した。また、粒子の導電性を以下の手順で測定した。それらの結果を以下の表1に示す。また、実施例1の粒子について、粒子断面における径方向での銅及びニッケルの分布状態を元素マッピングによって測定した。その結果を図2に示す。更に銅及びニッケルの量の分析を行った。その結果を図3に示す。粒子の断面作製にはFIB(株式会社日立製作所製のFB−2100A)を用いた。また銅及びニッケルのマッピング並びに銅及びニッケルの量の分析には、SEM(Carl Zeiss製のSUPRA55VP)、EDX(EDAX製のPegasus System(GenesisXM4))を用いた。
[Evaluation]
About the particle | grains obtained by the Example and the comparative example, the primary particle diameter and the ratio of the nickel which occupy in particle | grains were measured by the above-mentioned method. Further, the diameter of the central region and the thickness of the transition region and the surface region were measured from elemental mapping of copper and nickel in the radial direction in the particle cross section. Furthermore, the oxidation resistance of the particles was evaluated by the following procedure by thermogravimetry (TG). Further, the conductivity of the particles was measured by the following procedure. The results are shown in Table 1 below. Moreover, about the particle | grains of Example 1, the distribution state of the copper and nickel in the radial direction in a particle cross section was measured by element mapping. The result is shown in FIG. Furthermore, the amount of copper and nickel was analyzed. The result is shown in FIG. FIB (FB-2100A manufactured by Hitachi, Ltd.) was used for the cross-sectional preparation of the particles. Moreover, SEM (SUPRA55VP made by Carl Zeiss), EDX (Pegasus System (GenesisXM4 made by EDAX)) were used for the mapping of copper and nickel and the analysis of the amount of copper and nickel.
〔TGによる耐酸化性の評価〕
熱重量測定装置(セイコーインスツルメンツ株式会社製のTG/DTA6300)を用いた。試料の質量を13mgとし、大気雰囲気中、昇温速度10℃/minで試料を加熱し、質量変化を測定した。質量が1%増加した時点での温度を求め、耐酸化性の指標とした。この温度が高いほど耐酸化性が良好であることを意味する。
[Evaluation of oxidation resistance by TG]
A thermogravimetric apparatus (TG / DTA6300 manufactured by Seiko Instruments Inc.) was used. The mass of the sample was 13 mg, and the sample was heated in the air atmosphere at a temperature rising rate of 10 ° C./min, and the change in mass was measured. The temperature when the mass increased by 1% was determined and used as an index of oxidation resistance. Higher temperature means better oxidation resistance.
〔粒子の導電性の測定〕
粒子の導電性は、圧粉抵抗測定による体積抵抗率で評価した。測定装置として三菱化学製のロレスタGP MCP−T600を用い、4端子4探針法に従い測定した。測定時の圧力負荷は1000kgf/cm2とした。
[Measurement of conductivity of particles]
The conductivity of the particles was evaluated by the volume resistivity based on the dust resistance measurement. A Loresta GP MCP-T600 manufactured by Mitsubishi Chemical Corporation was used as a measuring device, and the measurement was performed according to a 4-terminal 4-probe method. The pressure load at the time of measurement was 1000 kgf / cm 2 .
図2及び図3に示すように、実施例1の銅粒子は、中心域の主要構成元素が銅であり、ニッケルが少量含まれていることが判る。また、中心域の外側に、ニッケルの割合が漸増するとともに銅の割合が漸減する遷移域が存在し、その外側に銅の割合よりもニッケル又はコバルトの割合の方が高くなっている表面域が存在することが判る。なお図には示していないが、実施例2の銅粒子も、実施例1の銅粒子と同様の元素分布を有していた。 As shown in FIGS. 2 and 3, the copper particles of Example 1 are found to have copper as the main constituent element in the central region and a small amount of nickel. In addition, a transition region in which the proportion of nickel gradually increases and the proportion of copper gradually decreases outside the central region, and a surface region in which the proportion of nickel or cobalt is higher than the proportion of copper on the outside thereof It can be seen that it exists. Although not shown in the figure, the copper particles of Example 2 also had the same element distribution as the copper particles of Example 1.
また表1に示す結果から明らかなように、各実施例の銅粒子は、各比較例の粒子に比べて耐酸化性が高いことが判る。また、各実施例の銅粒子は、銅のみからなる比較例1の粒子に近い実用的な導電性を有することが判る。 Further, as is apparent from the results shown in Table 1, it can be seen that the copper particles of each example have higher oxidation resistance than the particles of each comparative example. Moreover, it turns out that the copper particle of each Example has practical electroconductivity close | similar to the particle | grains of the comparative example 1 which consists only of copper.
Claims (8)
前記銅粒子の中心域は、主要構成元素が銅であり、
前記中心域から粒子表面に向かうに連れてニッケル又はコバルトの割合が漸増しているとともに銅の割合が漸減しており、
前記表面域は、銅と、ニッケル及びコバルトのうちの少なくとも一方とを含み、かつ銅の割合よりもニッケル及びコバルトの合計量の割合の方が高くなっており、
中心域においては、粒子の径方向での銅と、ニッケル及びコバルトの合計量との比率が略一定になっている銅粒子。 A copper particle comprising at least one of nickel and cobalt, wherein nickel or cobalt is unevenly distributed in the surface area of the particle,
In the central region of the copper particles, the main constituent element is copper,
As the ratio of nickel or cobalt gradually increases from the central area toward the particle surface, the ratio of copper gradually decreases.
The surface area includes copper and at least one of nickel and cobalt, and the ratio of the total amount of nickel and cobalt is higher than the ratio of copper ,
In the central region, copper particles in which the ratio of copper in the radial direction of the particles to the total amount of nickel and cobalt is substantially constant .
中心域の直径が一次粒子径の45〜90%である請求項1に記載の銅粒子。 The primary particle size is 50-2000 nm,
Copper particles of claim 1 the diameter of the central zone is 45 to 90% of the primary particle size.
25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する工程を有する銅粒子の製造方法。 A first electrode whose standard electrode potential at 25 ° C. is 0.34 to −0.36 (E / V) in an aqueous slurry containing cuprous oxide particles and a water-soluble compound of at least one of nickel and cobalt. Of reducing agent, and then
The manufacturing method of the copper particle which has the process of adding the 2nd reducing agent whose standard electrode potential in 25 degreeC is less than -0.36 (E / V) with a 1st reducing agent.
ニッケル及びコバルトのうちの少なくとも一方の水溶性化合物を添加し、次いで、
25℃での標準電極電位が−0.36(E/V)未満である第2の還元剤を、第1の還元剤ととともに添加する工程を有する銅粒子の製造方法。 A first reducing agent having a standard electrode potential of 0.34 to −0.36 (E / V) at 25 ° C. is added to the aqueous slurry containing cuprous oxide particles,
Adding at least one water-soluble compound of nickel and cobalt;
The manufacturing method of the copper particle which has the process of adding the 2nd reducing agent whose standard electrode potential in 25 degreeC is less than -0.36 (E / V) with a 1st reducing agent.
A conductive paste comprising the copper particles according to any one of claims 1 to 5 .
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WO2015122345A1 (en) * | 2014-02-12 | 2015-08-20 | 東レ株式会社 | Conductive paste, method for producing pattern, method for producing conductive pattern, and sensor |
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