JP5576319B2 - Copper particles - Google Patents
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- JP5576319B2 JP5576319B2 JP2011044539A JP2011044539A JP5576319B2 JP 5576319 B2 JP5576319 B2 JP 5576319B2 JP 2011044539 A JP2011044539 A JP 2011044539A JP 2011044539 A JP2011044539 A JP 2011044539A JP 5576319 B2 JP5576319 B2 JP 5576319B2
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims description 232
- 239000010949 copper Substances 0.000 title claims description 228
- 229910052802 copper Inorganic materials 0.000 title claims description 228
- 239000002245 particle Substances 0.000 title claims description 206
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 261
- 229910052759 nickel Inorganic materials 0.000 claims description 129
- 230000007704 transition Effects 0.000 claims description 79
- 229910052709 silver Inorganic materials 0.000 claims description 76
- 239000004332 silver Substances 0.000 claims description 76
- 239000003638 chemical reducing agent Substances 0.000 claims description 64
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 63
- 229910017052 cobalt Inorganic materials 0.000 claims description 53
- 239000010941 cobalt Substances 0.000 claims description 53
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 53
- 239000002002 slurry Substances 0.000 claims description 48
- 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
- -1 silver ions Chemical class 0.000 claims description 22
- 238000004519 manufacturing process Methods 0.000 claims description 21
- 239000000470 constituent Substances 0.000 claims description 20
- 238000007747 plating Methods 0.000 claims description 18
- 150000001875 compounds Chemical class 0.000 claims description 17
- 239000007864 aqueous solution Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 239000011164 primary particle Substances 0.000 claims description 12
- 230000007423 decrease Effects 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 11
- 238000006467 substitution reaction Methods 0.000 claims description 10
- 230000003247 decreasing effect Effects 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 description 21
- 238000007254 oxidation reaction Methods 0.000 description 21
- 238000006722 reduction reaction Methods 0.000 description 15
- 239000007788 liquid Substances 0.000 description 14
- 239000002243 precursor Substances 0.000 description 12
- 230000009467 reduction Effects 0.000 description 12
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 10
- 239000007771 core particle Substances 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 238000006073 displacement reaction Methods 0.000 description 8
- 238000009826 distribution Methods 0.000 description 8
- 229910001453 nickel ion Inorganic materials 0.000 description 8
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-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
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000011162 core material Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000011521 glass Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-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
- 229910001961 silver nitrate Inorganic materials 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
- 230000032683 aging Effects 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 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
- 238000001914 filtration 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
- 238000000926 separation method Methods 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
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-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
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 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
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006243 chemical reaction Methods 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
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000007641 inkjet printing Methods 0.000 description 2
- 229910052809 inorganic oxide Inorganic materials 0.000 description 2
- 238000013507 mapping Methods 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
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-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
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 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
- 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 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
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 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
- 239000002253 acid Substances 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
- 239000011668 ascorbic acid Substances 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 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
- 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 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
- 239000003153 chemical reaction reagent Substances 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
- XXJWXESWEXIICW-UHFFFAOYSA-N diethylene glycol monoethyl ether Chemical compound CCOCCOCCO XXJWXESWEXIICW-UHFFFAOYSA-N 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000009429 electrical wiring Methods 0.000 description 1
- 238000000921 elemental analysis Methods 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
- 239000008103 glucose Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 230000001771 impaired effect Effects 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
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 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
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002994 raw material Substances 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
- 150000003378 silver Chemical class 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
- 229940100890 silver compound Drugs 0.000 description 1
- 150000003379 silver compounds Chemical class 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
- 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
- 239000011975 tartaric acid Substances 0.000 description 1
- 235000002906 tartaric acid Nutrition 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
Images
Description
本発明は、銀とニッケル又はコバルトとを含有する銅粒子に関する。 The present invention relates to copper particles containing silver and nickel or 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、中心域、表面域、及び該中心域と該表面域との間に位置する遷移域を有し、主要構成元素が銅であり、更に銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む銅粒子であって、
前記中心域は、主要構成元素が銅であり、
前記遷移域においては、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、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含んでいる銅粒子を提供するものである。
The present invention has a central region, a surface region, and a transition region located between the central region and the surface region, the main constituent element is copper, and at least one of silver, nickel, and cobalt A copper particle containing
In the central region, the main constituent element is copper,
In the transition region, the ratio of nickel or cobalt gradually increases toward the particle surface and the ratio of copper gradually decreases.
The surface area provides copper particles containing silver and at least one of nickel and cobalt.
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との水溶性化合物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の還元剤を添加して、主要構成元素が銅である中心域を形成し、
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して、中心域の表面に、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いる遷移域を形成し、次いで、
前記遷移域までが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域に含まれる銅を溶解させるとともに該遷移域の表面に銀を還元析出させる置換めっきを行い、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む表面域を形成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 slurry having a standard electrode potential at 25 ° C. of 0.34 to −0.36 (E / V) in an aqueous slurry containing a water-soluble compound of cuprous oxide particles and at least one of nickel and cobalt. To form a central region where the main constituent element is copper,
A second reducing agent having a standard electrode potential of less than −0.36 (E / V) at 25 ° C. is added together with the first reducing agent, and the surface of the central region is moved toward the particle surface. Forming a transition zone in which the proportion of nickel or cobalt is gradually increased and the proportion of copper is gradually decreased;
The particles formed up to the transition region are brought into contact with an aqueous solution containing silver ions to dissolve the copper contained in the transition region and perform substitution plating for reducing and depositing silver on the surface of the transition region. And the manufacturing method of the copper particle which has the process of forming the surface area containing at least one of nickel and cobalt.
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の還元剤を添加して、主要構成元素が銅である中心域を形成し、
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して、中心域の表面に、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いる遷移域を形成し、次いで、
前記遷移域までが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域に含まれる銅を溶解させるとともに該遷移域の表面に銀を還元析出させる置換めっきを行い、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む表面域を形成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 at 25 ° C. of 0.34 to −0.36 (E / V) is added to the aqueous slurry containing cuprous oxide particles, and the main constituent element is copper. Forming a central area,
Adding at least one water-soluble compound of nickel and cobalt;
A second reducing agent having a standard electrode potential of less than −0.36 (E / V) at 25 ° C. is added together with the first reducing agent, and the surface of the central region is moved toward the particle surface. Forming a transition zone in which the proportion of nickel or cobalt is gradually increased and the proportion of copper is gradually decreased;
The particles formed up to the transition region are brought into contact with an aqueous solution containing silver ions to dissolve the copper contained in the transition region and perform substitution plating for reducing and depositing silver on the surface of the transition region. And the manufacturing method of the copper particle which has the process of forming the surface area containing at least one of nickel and cobalt.
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し、銀とニッケル又はコバルトとを含有する銅粒子が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the copper particle which has high oxidation resistance and has the electroconductivity close | similar to a copper simple substance, and contains silver, nickel, or cobalt is 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、添加元素として少量の銀とニッケル又はコバルトとを含有するものである。銀とニッケル又はコバルトと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 silver and nickel or cobalt as additive elements. Silver and nickel or cobalt are 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３つの部位に大別される。この３つの部位は、中心域、表面域、及び該中心域と該表面域との間に位置する遷移域である。中心域とは、これら３つの部位のうち、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。図１には、本発明の銅粒子における銅、銀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 three parts along the radial direction. These three parts are a central region, a surface region, and a transition region located between the central region and the surface region. The central region is a portion located on the innermost side of the copper particles among these three portions. The surface area is a portion including the outermost surface of the copper particles and extending from the outermost surface to a predetermined depth. FIG. 1 shows an example of the relationship between the radial distribution of copper, silver, nickel and the like in the copper particles of the present invention, and the central region A, transition region B, and surface region 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、銀及び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Ａ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。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。なお、本発明における存在割合とはａｔｍ％（原子％）での割合のことである。 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 contain silver, nickel, and the like, but as a whole, develop a property close to copper. The central region A of the copper particles is a portion made of only copper or containing 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. The minor constituent element refers to an element having an existing ratio of the element of 40 atm% or less, particularly 30 atm% or less. In addition, the presence rate in this invention is a rate in atm% (atomic%).
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Ａ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、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 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 and nickel in the central area A is within this range, the copper particles of the present invention contain nickel or the like, which is a metal having lower conductivity than copper, but as a whole, copper. It exhibits conductivity close to a simple substance.
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、４５〜７５％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%, more preferably 45 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とは、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。しかし遷移域Ｂは銀を含有していない。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 in which nickel or the like is unevenly distributed 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. However, transition zone B does not contain silver. 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、２１．５〜５１．５％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 21.5 to 51.5%.
次に表面域Ｃについて説明する。表面域Ｃは、銀、ニッケル及びコバルトのうちの少なくとも一方及び銅を含んでいる。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における銅の存在割合は、ニッケル及びコバルトの合計量の存在割合よりも低くなっている。表面域Ｃにおける最表面、すなわち本発明の銅粒子における最表面は、銀と、ニッケル及びコバルトのうちの少なくとも一方とのみから構成されており、銅は実質的に存在していないことが好ましい。尤も、本発明の効果を損なわない範囲で多少の銅が存在しても良い。一方、表面域Ｃにおける遷移域Ｂ寄りの部位には、銀及びニッケル及びコバルトのうちの少なくとも一方に加えて少量の銅が存在している。 Next, the surface area C will be described. The surface area C contains at least one of silver, nickel, and cobalt and copper. 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. The existing ratio of copper in the surface region C is lower than the existing ratio of the total amount of nickel and cobalt. The outermost surface in the surface region C, that is, the outermost surface in the copper particles of the present invention is composed of only silver and at least one of nickel and cobalt, and it is preferable that copper is not substantially present. However, some copper may be present as long as the effects of the present invention are not impaired. On the other hand, in a portion near the transition region B in the surface region C, a small amount of copper is present in addition to at least one of silver, nickel, and cobalt.
上述したとおり、表面域Ｃの最表面は銀及びニッケル等のみから構成されていることが好ましい。本発明の銅粒子耐酸化性を高める観点からは、表面域Ｃの最表面は、酸化されにくい元素である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、最表面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十分に高めることが容易でなくなる。そこで、最表面にニッケル等に加えて銀を存在させることで、この銀と、遷移域Ｂ及び中心域Ａに含まれる銅とが直接接するようになり、粒子全体の導電性を一層高めることができる。しかも銀は銅よりも酸化されにくい金属なので、銀を最表面に存在させることで、本発明の銅粒子の耐酸化性の低下も防止できる。このような理由によって、本発明の銅粒子によれば、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。 As described above, the outermost surface of the surface region C is preferably composed only of silver, nickel, and the like. From the viewpoint of improving the oxidation resistance of the copper particles of the present invention, the outermost surface of the surface region C is advantageously composed only of nickel, which is an element that is difficult to oxidize, but nickel is more conductive than copper. If the outermost surface is composed only of nickel or the like, it is not easy to sufficiently enhance the conductivity of the copper particles of the present invention. Therefore, by making silver exist in addition to nickel or the like on the outermost surface, this silver and the copper contained in the transition region B and the central region A come into direct contact, and the conductivity of the entire particle can be further enhanced. it can. And since silver is a metal which is harder to oxidize than copper, the fall of the oxidation resistance of the copper particle of this invention can also be prevented by making silver exist in the outermost surface. For these reasons, according to the copper particles of the present invention, conductivity can be maintained without impairing oxidation resistance.
なお図１においては、表面域Ｃにおける最表面は、ニッケル等の存在割合の方が銀の存在割合よりも高くなっている状態が示されているが、これは本発明の一例であって、両者の存在割合の大小は、本発明の銅粒子の具体的な用途に応じて適宜変更することができる。すなわち、最表面における銀の存在割合を、ニッケル等の存在割合よりも高くすることもでき、あるいは両者の存在割合を同じにすることもできる。例えば本発明の銅粒子からペーストを調製して、電気配線を形成する場合に、低めの焼成温度が要求される用途では、最表面における銀の存在割合をニッケル及びコバルトの合計量の存在割合よりも高くすることが有利である。逆に、高めの焼成温度が要求される用途では、最表面におけるニッケル及びコバルトの合計量の存在割合を銀の存在割合よりも高くすることが有利である。また、特に高い耐酸化性が要求される用途の場合も、最表面におけるニッケル及びコバルトの合計量の存在割合を銀の存在割合よりも高くすることが有利である。例えば最表面におけるニッケル及びコバルトの合計量の存在割合を５１〜９９ａｔｍ％、特に６０〜７０ａｔｍ％とすることが好ましく、銀の割合を１〜４９ａｔｍ％、特に３０〜４０ａｔｍ％とすることが好ましい。 In FIG. 1, the outermost surface in the surface region C shows a state in which the abundance ratio of nickel or the like is higher than the abundance ratio of silver, but this is an example of the present invention, The magnitude of the ratio of both can be changed as appropriate according to the specific application of the copper particles of the present invention. That is, the abundance ratio of silver on the outermost surface can be made higher than the abundance ratio of nickel or the like, or the abundance ratio of both can be made the same. For example, when an electric wiring is formed by preparing a paste from the copper particles of the present invention, in applications where a lower firing temperature is required, the proportion of silver on the outermost surface is greater than the proportion of the total amount of nickel and cobalt. Is also advantageous. On the contrary, in applications where a higher firing temperature is required, it is advantageous to make the ratio of the total amount of nickel and cobalt on the outermost surface higher than the ratio of silver. Also, in the case of applications that require particularly high oxidation resistance, it is advantageous to make the existing ratio of the total amount of nickel and cobalt on the outermost surface higher than the existing ratio of silver. For example, the ratio of the total amount of nickel and cobalt on the outermost surface is preferably 51 to 99 atm%, particularly preferably 60 to 70 atm%, and the ratio of silver is preferably 1 to 49 atm%, particularly 30 to 40 atm%.
表面域Ｃにおいて銀は、最表面における存在割合が最も高く、最表面から粒子内部に向かうに連れて存在割合が漸減している。また表面域Ｃにおいてニッケル等も、最表面における存在割合が最も高く、最表面から粒子内部に向かうに連れて存在割合が漸減している。このように、表面域Ｃにおいては、銀及びニッケル等の存在割合が、粒子の径方向に沿って連続的に変化しているので、本発明の銅粒子は、例えば銅の芯粒子の表面に銀を被覆して導電性を高めた従来の銅粒子に比べて、銀の剥離が起こりにくくなっている。 In the surface region C, silver has the highest abundance ratio on the outermost surface, and the abundance ratio gradually decreases from the outermost surface toward the inside of the particle. In the surface area C, nickel and the like are present at the highest ratio on the outermost surface and gradually decrease from the outermost surface toward the inside of the particle. Thus, in the surface area C, since the abundance ratio of silver, nickel, and the like continuously changes along the diameter direction of the particles, the copper particles of the present invention are, for example, on the surface of the copper core particles. Compared with the conventional copper particle which covered silver and improved electroconductivity, peeling of silver becomes difficult to occur.
また表面域Ｃにおける遷移域Ｂ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、表面域と遷移域との境界を挟んで、表面域と遷移域とでニッケル等の存在割合が連続的に変化している。銅に関しても同様であり、表面域Ｃにおける遷移域寄りＢ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Ｂの説明に関して先に述べたとおり、表面域Ｃと遷移域Ｂとの境界を挟んで、表面域Ｃと遷移域Ｂ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、表面域Ｃと遷移域Ｂ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。 Further, in the region close to the transition region B in the surface region C, the abundance ratio of nickel or the like gradually decreases toward the inside of the particle, and the surface region and the transition region are sandwiched between the boundary between the surface region and the transition region. The ratio of nickel and the like continuously changes. The same applies to copper. In the region near the transition region B in the surface region C, the proportion of copper gradually increases toward the inside of the particle. As described above with respect to the explanation of the transition region B, The existing ratio of copper continuously changes between the surface region C and the transition region B across the boundary between the region C and the transition region B. As a result, the integrity of the surface area C and the transition area B is increased, and separation at the boundary between both areas is less likely to occur.
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、３．５〜３３．５％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 3.5 to 33.5% of the primary particle diameter of the copper particles. When the thickness of the surface area 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における銀の割合は、銀とニッケル等と銅との合計量に対して５〜７０ａｔｍ％であることが好ましく、５〜６５ａｔｍ％であることが更に好ましく、５〜６０ａｔｍ％であることが一層好ましい。ニッケル及びコバルトの合計量の割合は、銀とニッケル等と銅との合計量に対して２５〜６０ａｔｍ％であることが好ましく、３０〜５５ａｔｍ％であることが更に好ましく、３５〜５０ａｔｍ％であることが一層好ましい。更に銅の割合は、銀とニッケル等と銅との合計量に対して５〜７０ａｔｍ％であることが好ましく、５〜６５ａｔｍ％であることが更に好ましく、５〜６０ａｔｍ％であることが一層好ましい。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、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。 The ratio of silver in the surface area C is preferably 5 to 70 atm%, more preferably 5 to 65 atm%, and 5 to 60 atm% with respect to the total amount of silver, nickel and the like and copper. Is more preferable. The ratio of the total amount of nickel and cobalt is preferably 25 to 60 atm%, more preferably 30 to 55 atm%, and more preferably 35 to 50 atm% with respect to the total amount of silver, nickel and the like and copper. More preferably. Furthermore, the ratio of copper is preferably 5 to 70 atm%, more preferably 5 to 65 atm%, and further preferably 5 to 60 atm% with respect to the total amount of silver, nickel and the like and copper. . The ratio of copper and nickel in the surface area C is within this range, so that the copper particles of the present invention contain nickel or the like, which is a metal having lower conductivity than copper, but as a whole copper. It exhibits conductivity close to a simple substance.
表面域Ｃの厚みや該表面域Ｃでの銀、ニッケル等及び銅の割合、遷移域Ｂの厚みや該遷移域Ｂでのニッケル等及び銅の割合、並びに中心域Ａの直径や該中心域Ａでのニッケル等及び銅の割合は、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, the ratio of silver, nickel, etc. and copper in the surface area C, the thickness of the transition area B, the ratio of nickel etc. and copper in the transition area B, the diameter of the central area A and the central area The ratio of nickel or the like and copper in A can be obtained by preparing a sample of a cross section of copper particles 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。また、本発明の銅粒子全体に占める銀の割合は、導電性と経済性とのバランスの点から、０．１〜２０ａｔｍ％であることが好ましく、１〜１５ａｔｍ％であることが更に好ましい。これらの割合は、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. Moreover, it is preferable that the ratio of the silver to the whole copper particle of this invention is 0.1-20 atm% from the point of the balance of electroconductivity and economical efficiency, and it is still more preferable that it is 1-15 atm%. These ratios 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 spectroscopic analyzer.
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５０ｎｍ〜２μｍに設定することが好ましく、２００ｎｍ〜１μｍ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 nm to 2 μm, and preferably set to 200 nm to 1 μm. 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.
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の還元剤を添加して、主要構成元素が銅である中心域Ａを形成し、（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して、中心域Ａの表面に、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いる遷移域Ｂを形成し、次いで、（１−３）遷移域Ｂまでが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域Ｂに含まれる銅を溶解させるとともに該遷移域Ｂの表面に銀を還元析出させる置換めっきを行い、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む表面域Ｃを形成する。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 of .36 (E / V) is added to form a central region A in which the main constituent element is copper, and (1-2) the standard electrode potential at −25 ° C. is −0.36. A second reducing agent that is less than (E / V) is added together with the first reducing agent, and the ratio of nickel or cobalt gradually increases toward the particle surface on the surface of the central region A. Together with the transition region B in which the ratio of copper gradually decreases, and then (1-3) the particles formed up to the transition region B are brought into contact with an aqueous solution containing silver ions. A substitution plating that dissolves copper contained and reduces silver on the surface of the transition zone B. It was carried out, to form a silver surface area C and at least one of nickel and cobalt. 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「芯材粒子」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芯材粒子中に、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。この状態の芯材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。芯材粒子は、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 “core material 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 or 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 core material particles generated by reduction of the cuprous oxide particles. It is formed and contained in a small amount. The distribution of nickel and the like in the core particles in this state is substantially uniform in the radial direction of the particles. The core material particles substantially correspond to the central area A of 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、芯材粒子の表面に、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が形成される。遷移域Ｂ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、芯材粒子の表面に遷移域Ｂが形成される。この時点での銅及びニッケルの径方向での分布の一例は図２に示すとおりとなる。 By adding the first and second reducing agents, copper, nickel and the like are deposited on the surface of the core material particles. Thereby, the transition zone B in the target copper particle is formed. In order to successfully form the transition zone B, it is necessary to adjust the temperature of the aqueous slurry as described above, and the usage ratio of the first reducing agent and the second reducing agent is appropriately adjusted. It is also necessary. 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 core particle. An example of the distribution in the radial direction of copper and nickel at this time is as shown in FIG.
遷移域Ｂまでが形成された粒子（以下、この粒子を「前駆体粒子」という。）に対して（１−３）の工程を行う。本工程においては、粒子と、銀イオンを含む水溶液とを接触させて、銀と銅との置換めっきを行う。例えば銀イオンを含む水溶液中に前駆体粒子を投入し、液を攪拌する。銀と銅とのイオン化傾向の違いに起因して、遷移域に含まれる銅が液中に溶解するとともに、液中の銀イオンが還元されて遷移域の表面に銀が析出する。遷移域Ｂに存在しているニッケル等には変化は生じない。その結果、前駆体粒子の表面において、銅と銀とが置換されて、銀の存在割合が増加し、かつ銅の存在割合が減少する。その結果、表面域Ｃが形成される。この場合、置換めっきの条件を適切に調整することで、粒子の最表面を、銀とニッケル等のみから構成することができる。 The step (1-3) is performed on the particles formed up to the transition region B (hereinafter, these particles are referred to as “precursor particles”). In this step, substitution plating of silver and copper is performed by bringing particles into contact with an aqueous solution containing silver ions. For example, precursor particles are put into an aqueous solution containing silver ions, and the liquid is stirred. Due to the difference in ionization tendency between silver and copper, copper contained in the transition region is dissolved in the liquid, and silver ions in the liquid are reduced, so that silver is deposited on the surface of the transition region. There is no change in nickel or the like present in the transition region B. As a result, copper and silver are substituted on the surface of the precursor particles, the silver content increases, and the copper content decreases. As a result, a surface area C is formed. In this case, the outermost surface of the particles can be composed only of silver and nickel by appropriately adjusting the conditions of displacement plating.
銀イオンを含む水溶液は、前駆体粒子を含むスラリー中に一括添加することもでき、あるいは所定の時間にわたって逐次添加することもできる。置換めっきのコントロールのしやすさの観点からは、逐次添加を行うことが好ましい。 The aqueous solution containing silver ions can be added all at once to the slurry containing the precursor particles, or can be added sequentially over a predetermined time. From the viewpoint of ease of control of displacement plating, it is preferable to perform sequential addition.
置換めっきを行うために用いられる銀源としては、水溶性の銀化合物を用いることができる。そのような化合物としては、例えば硝酸銀、酢酸銀、ヨウ化銀、塩化銀、酸化銀、臭化銀、シアン化銀などが挙げられる。水溶液中における銀イオンの濃度は０．００１３〜０．２６モル／リットルとすることが好ましく、0.０１３〜０．１８モル／リットルとすることが更に好ましい。投入する前駆体粒子の量は、水溶液中における銀イオンの濃度が前記の範囲内であることを条件として、水溶液１リットルあたり１０〜６００ｇとすることが好ましく、５０〜３００ｇとすることが更に好ましい。 As a silver source used for displacement plating, a water-soluble silver compound can be used. Examples of such compounds include silver nitrate, silver acetate, silver iodide, silver chloride, silver oxide, silver bromide, and silver cyanide. The concentration of silver ions in the aqueous solution is preferably 0.0013 to 0.26 mol / liter, and more preferably 0.013 to 0.18 mol / liter. The amount of precursor particles to be added is preferably 10 to 600 g, more preferably 50 to 300 g per liter of the aqueous solution, provided that the concentration of silver ions in the aqueous solution is within the above range. .
置換めっきを行うに際しては、液中にＥＤＴＡ（エチレンジアミン四酢酸）、酒石酸、クエン酸、オキシカルボン酸等のカルボキシル化合物、アルコールアミン化合物又はアルキルアミン化合物などを共存させておいてもよい。こうすることで、安定的に粒子表面に存在する銅を錯体化させることができるからである。この目的のために、水溶液中におけるＥＤＴＡ等の濃度は、９．５×１０-4〜１．９×１０-1モル／リットルとすることが好ましく、９．５×１０-3〜１．４×１０-1モル／リットルとすることが更に好ましい。 When performing displacement plating, a carboxyl compound such as EDTA (ethylenediaminetetraacetic acid), tartaric acid, citric acid, and oxycarboxylic acid, an alcoholamine compound, or an alkylamine compound may coexist in the solution. By doing so, copper existing on the particle surface can be stably complexed. For this purpose, the concentration of EDTA or the like in the aqueous solution is preferably 9.5 × 10 −4 to 1.9 × 10 −1 mol / liter, and 9.5 × 10 −3 to 1.4. More preferably, it is set to × 10 −1 mol / liter.
置換めっきの温度は、銀と銅との置換の程度に応じて適宜設定することができる。置換めっきの時間についても同様である。置換量を多くして、目的とする銅粒子における銀の割合を高めたい場合には、比較的長時間にわたり置換めっきを行えばよく、逆に銀の割合をあまり高くしたくない場合には、置換めっきを比較的短時間で終了させればよい。 The temperature of displacement plating can be appropriately set according to the degree of substitution between silver and copper. The same applies to the time for displacement plating. If you want to increase the amount of substitution and increase the proportion of silver in the target copper particles, you only need to perform substitution plating for a relatively long time, and conversely if you do not want to make the proportion of silver too high, The displacement plating may be completed in a relatively short time.
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Ａ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 distribution in the radial direction of the copper particles in the central region A of the copper particles, as shown in FIG. A small amount of nickel or the like is contained. 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の還元剤を添加して、主要構成元素が銅である中心域Ａを形成し、（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、（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して、中心域Ａの表面に、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いる遷移域Ｂを形成し、次いで、（２−４）遷移域Ｂまでが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域Ｂに含まれる銅を溶解させるとともに該遷移域の表面に銀を還元析出させる置換めっきを行い、銀とニッケル又はコバルトとを含む表面域Ｃを形成する。
[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. To form a central region A in which the main constituent element is copper, (2-2) at least one water-soluble compound of nickel and cobalt is added to the aqueous slurry, and (2-3) 25 ° C. A second reducing agent having a standard electrode potential of less than −0.36 (E / V) is added together with the first reducing agent, and toward the surface of the central region A toward the particle surface. A transition region B in which the proportion of nickel or cobalt is gradually increased and the proportion of copper is gradually decreased is formed, and then (2-4) particles formed up to the transition region B, an aqueous solution containing silver ions, In contact with the copper to dissolve copper contained in the transition region B and the surface of the transition region Perform substitution plating to reduction precipitation of silver, to form a surface zone C comprising silver and nickel or cobalt.
（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芯材粒子は、目的とする銅粒子における中心域にほぼ対応する。この芯材粒子は、先に述べた製造方法１の（１−１）の工程で生成する芯材粒子と異なり、該粒子中にニッケル等を含有することはない。芯材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 core particle produced | generated in the process of (2-1) respond | corresponds substantially to the center area | region in the target copper particle. Unlike the core particles produced in the step (1-1) of the production method 1 described above, the core particles do not contain nickel or the like in the particles. This is because nickel ions or the like do not exist in the reaction system when the core material 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芯材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, the core particles generated by the 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）の工程を行い、引き続き（２−４）の工程を行う。本工程では、製造方法１の工程（１−２）及び（１−３）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）及び（１−３）に関する説明が適宜適用される。 Next, the process (2-3) is performed, and then the process (2-4) is performed. In this step, operations similar to those in steps (1-2) and (1-3) of manufacturing method 1 are performed. Therefore, for the details of this step, the description regarding the steps (1-2) and (1-3) 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.
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〕
工程（１−１）
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芯材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]
Step (1-1)
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, core material 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.
工程（１−２）
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、前駆体粒子を得た。
Step (1-2)
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, precursor particles were obtained.
工程（１−３）
得られた前駆体粒子を濾別して５０．０ｇを計り取った。計り取った前駆体粒子を、２．１ｇのＥＤＴＡ等とともに純水０．２５リットルに投入し、５分間攪拌した。次に、硝酸銀２．４ｇを純水０．１２リットルに溶解してなる硝酸銀水溶液を３０分にわたり逐次添加して置換めっき反応を行った。硝酸銀水溶液の添加完了後、５分間熟成させて、目的とする銅粒子を得た。
Step (1-3)
The obtained precursor particles were separated by filtration and weighed 50.0 g. The measured precursor particles were put into 0.25 liter of pure water together with 2.1 g of EDTA, and stirred for 5 minutes. Next, an aqueous solution of silver nitrate obtained by dissolving 2.4 g of silver nitrate in 0.12 liters of pure water was sequentially added over 30 minutes to perform a displacement plating reaction. After completion of the addition of the aqueous silver nitrate solution, aging was performed for 5 minutes to obtain the intended copper particles.
〔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.
〔参考例１及び２〕
本参考例は、実施例１及び２において、工程（１−２）までを行って得られた前駆体粒子である。この前駆体粒子は、銅及びニッケルのみからなるものであり、銀を含んでいない。
[Reference Examples 1 and 2]
This reference example is a precursor particle obtained in Examples 1 and 2 up to step (1-2). This precursor particle consists only of copper and nickel, and does not contain silver.
〔評価〕
実施例及び比較例並びに参考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及び銀の割合を、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、ニッケル及び銀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。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、ニッケル及び銀のマッピング並びに銅、ニッケル及び銀の量の分析には、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, the comparative example, and the reference example, the primary particle diameter and the ratio of nickel and silver 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, nickel and silver 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. FIB (FB-2100A manufactured by Hitachi, Ltd.) was used for the cross-sectional preparation of the particles. SEM (SUPRA55VP manufactured by Carl Zeiss) and EDX (Pegasus System (GenesisXM4 manufactured by EDAX)) were used for mapping copper, nickel, and silver and for analyzing the amounts of copper, nickel, and silver.
〔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 .
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。また、表には示していないが、各実施例の銅粒子は、銅、銀及びニッケルに関し、図１に示す分布を有していた。また、各実施例と各参考例との対比から明らかなように、参考例で得られた前駆体粒子の表面を銀で置換めっきすることで、耐酸化性と導電性とが一層両立することが判る。 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. Moreover, although not shown in the table | surface, the copper particle of each Example had distribution shown in FIG. 1 regarding copper, silver, and nickel. In addition, as is clear from the comparison between each example and each reference example, the surface of the precursor particles obtained in the reference example is replaced with silver so that the oxidation resistance and the conductivity are more compatible. I understand.
Claims (10)
前記中心域は、主要構成元素が銅であり、
前記遷移域においては、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、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含んでいる銅粒子。 Copper having a central region, a surface region, and a transition region located between the central region and the surface region, the main constituent element being copper, and further containing silver and at least one of nickel and cobalt Particles,
In the central region, the main constituent element is copper,
In the transition region, the ratio of nickel or cobalt gradually increases toward the particle surface and the ratio of copper gradually decreases.
The surface region is a copper particle containing silver and at least one of nickel and cobalt.
中心域の直径が一次粒子径の４０〜９０％である請求項３に記載の銅粒子。 The primary particle size is 50 nm to 2 μm,
The copper particle according to claim 3, wherein the diameter of the central region is 40 to 90% of the primary particle diameter.
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して、中心域の表面に、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いる遷移域を形成し、次いで、
前記遷移域までが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域に含まれる銅を溶解させるとともに該遷移域の表面に銀を還元析出させる置換めっきを行い、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む表面域を形成する工程を有する銅粒子の製造方法。 A first slurry having a standard electrode potential at 25 ° C. of 0.34 to −0.36 (E / V) in an aqueous slurry containing a water-soluble compound of cuprous oxide particles and at least one of nickel and cobalt. To form a central region where the main constituent element is copper,
A second reducing agent having a standard electrode potential of less than −0.36 (E / V) at 25 ° C. is added together with the first reducing agent, and the surface of the central region is moved toward the particle surface. Forming a transition zone in which the proportion of nickel or cobalt is gradually increased and the proportion of copper is gradually decreased;
The particles formed up to the transition region are brought into contact with an aqueous solution containing silver ions to dissolve the copper contained in the transition region and perform substitution plating for reducing and depositing silver on the surface of the transition region. And the manufacturing method of the copper particle which has the process of forming the surface area containing at least one of nickel and cobalt.
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して、中心域の表面に、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いる遷移域を形成し、次いで、
前記遷移域までが形成された粒子と、銀イオンを含む水溶液とを接触させて、該遷移域に含まれる銅を溶解させるとともに該遷移域の表面に銀を還元析出させる置換めっきを行い、銀と、ニッケル及びコバルトのうちの少なくとも一方とを含む表面域を形成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 at 25 ° C. of 0.34 to −0.36 (E / V) is added to the aqueous slurry containing cuprous oxide particles, and the main constituent element is copper. Forming a central area,
Adding at least one water-soluble compound of nickel and cobalt;
A second reducing agent having a standard electrode potential of less than −0.36 (E / V) at 25 ° C. is added together with the first reducing agent, and the surface of the central region is moved toward the particle surface. Forming a transition zone in which the proportion of nickel or cobalt is gradually increased and the proportion of copper is gradually decreased;
The particles formed up to the transition region are brought into contact with an aqueous solution containing silver ions to dissolve the copper contained in the transition region and perform substitution plating for reducing and depositing silver on the surface of the transition region. And the manufacturing method of the copper particle which has the process of forming the surface area containing at least one of nickel and cobalt.
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| JP5576318B2 (en) * | 2011-03-01 | 2014-08-20 | 三井金属鉱業株式会社 | Copper particles |
| US10062473B2 (en) * | 2012-01-17 | 2018-08-28 | Dowa Electronics Materials Co., Ltd. | Silver-coated copper alloy powder and method for producing same |
| WO2015133474A1 (en) * | 2014-03-05 | 2015-09-11 | 積水化学工業株式会社 | Conductive filler, method for manufacturing conductive filler, and conductive paste |
| JP2016094665A (en) * | 2014-11-07 | 2016-05-26 | 住友金属鉱山株式会社 | Silver coated copper powder and conductive paste using the same, conductive coating and conductive sheet |
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| JP4853152B2 (en) * | 2006-07-19 | 2012-01-11 | 住友金属鉱山株式会社 | Nickel-coated copper fine particles and manufacturing method thereof, dispersion using the same, manufacturing method thereof, and paste using the same |
| JP5176824B2 (en) * | 2008-09-26 | 2013-04-03 | 住友金属鉱山株式会社 | Silver-coated copper fine particles, dispersion thereof, and production method thereof |
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| JP5576318B2 (en) * | 2011-03-01 | 2014-08-20 | 三井金属鉱業株式会社 | Copper particles |
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