JP6799936B2 - Nickel particles, conductive paste, internal electrodes and multilayer ceramic capacitors - Google Patents
Nickel particles, conductive paste, internal electrodes and multilayer ceramic capacitors Download PDFInfo
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- JP6799936B2 JP6799936B2 JP2016072630A JP2016072630A JP6799936B2 JP 6799936 B2 JP6799936 B2 JP 6799936B2 JP 2016072630 A JP2016072630 A JP 2016072630A JP 2016072630 A JP2016072630 A JP 2016072630A JP 6799936 B2 JP6799936 B2 JP 6799936B2
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- Prior art keywords
- nickel
- particles
- nickel particles
- copper
- mass
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims description 451
- 239000002245 particle Substances 0.000 title claims description 304
- 229910052759 nickel Inorganic materials 0.000 title claims description 230
- 239000003985 ceramic capacitor Substances 0.000 title claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 58
- 239000002184 metal Substances 0.000 claims description 52
- 229910052802 copper Inorganic materials 0.000 claims description 42
- 239000010949 copper Substances 0.000 claims description 42
- -1 amine compound Chemical class 0.000 claims description 41
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 39
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 239000000919 ceramic Substances 0.000 claims description 16
- 230000004580 weight loss Effects 0.000 claims description 16
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 12
- 239000012298 atmosphere Substances 0.000 claims description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 12
- 239000011164 primary particle Substances 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 9
- 239000001257 hydrogen Substances 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- 229910052709 silver Inorganic materials 0.000 claims description 7
- 239000004332 silver Substances 0.000 claims description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 239000010931 gold Substances 0.000 claims description 6
- 229910052763 palladium Inorganic materials 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims description 6
- 239000003989 dielectric material Substances 0.000 claims description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 239000011574 phosphorus Substances 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 3
- 239000011593 sulfur Substances 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 description 56
- 238000000034 method Methods 0.000 description 38
- 125000001931 aliphatic group Chemical group 0.000 description 36
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 33
- 239000003960 organic solvent Substances 0.000 description 26
- 239000002002 slurry Substances 0.000 description 26
- 239000000243 solution Substances 0.000 description 25
- 229920000642 polymer Polymers 0.000 description 24
- 239000002270 dispersing agent Substances 0.000 description 23
- 238000006722 reduction reaction Methods 0.000 description 23
- 238000006243 chemical reaction Methods 0.000 description 19
- 230000009467 reduction Effects 0.000 description 18
- 150000001412 amines Chemical class 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 14
- 229910001453 nickel ion Inorganic materials 0.000 description 14
- 239000003981 vehicle Substances 0.000 description 13
- 230000002776 aggregation Effects 0.000 description 11
- 239000010419 fine particle Substances 0.000 description 11
- 238000005755 formation reaction Methods 0.000 description 11
- 239000000463 material Substances 0.000 description 11
- 230000008569 process Effects 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 9
- 239000011362 coarse particle Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 238000002156 mixing Methods 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 150000002815 nickel Chemical class 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 125000004432 carbon atom Chemical group C* 0.000 description 8
- 239000011162 core material Substances 0.000 description 8
- 238000009826 distribution Methods 0.000 description 8
- 239000003446 ligand Substances 0.000 description 8
- 150000002739 metals Chemical class 0.000 description 8
- 239000011259 mixed solution Substances 0.000 description 8
- 229920005989 resin Polymers 0.000 description 8
- 239000011347 resin Substances 0.000 description 8
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 7
- 238000004220 aggregation Methods 0.000 description 7
- 230000009918 complex formation Effects 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 230000006866 deterioration Effects 0.000 description 6
- 230000005389 magnetism Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000007639 printing Methods 0.000 description 6
- 238000005245 sintering Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 238000011282 treatment Methods 0.000 description 6
- 238000009835 boiling Methods 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000007772 electrode material Substances 0.000 description 5
- 229910021645 metal ion Inorganic materials 0.000 description 5
- 239000003921 oil Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000011946 reduction process Methods 0.000 description 5
- 239000006228 supernatant Substances 0.000 description 5
- QGLWBTPVKHMVHM-KTKRTIGZSA-N (z)-octadec-9-en-1-amine Chemical compound CCCCCCCC\C=C/CCCCCCCCN QGLWBTPVKHMVHM-KTKRTIGZSA-N 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 238000010494 dissociation reaction Methods 0.000 description 4
- 230000005593 dissociations Effects 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- 125000001302 tertiary amino group Chemical group 0.000 description 4
- 239000004034 viscosity adjusting agent Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 3
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 3
- 239000001856 Ethyl cellulose Substances 0.000 description 3
- 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 3
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 125000003277 amino group Chemical group 0.000 description 3
- 150000001879 copper Chemical class 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000032798 delamination Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229920001249 ethyl cellulose Polymers 0.000 description 3
- 235000019325 ethyl cellulose Nutrition 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 229940078487 nickel acetate tetrahydrate Drugs 0.000 description 3
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 3
- OINIXPNQKAZCRL-UHFFFAOYSA-L nickel(2+);diacetate;tetrahydrate Chemical compound O.O.O.O.[Ni+2].CC([O-])=O.CC([O-])=O OINIXPNQKAZCRL-UHFFFAOYSA-L 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 description 3
- 125000000467 secondary amino group Chemical group [H]N([*:1])[*:2] 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000001308 synthesis method Methods 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 2
- 229920000178 Acrylic resin Polymers 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- PLZVEHJLHYMBBY-UHFFFAOYSA-N Tetradecylamine Chemical compound CCCCCCCCCCCCCCN PLZVEHJLHYMBBY-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- QXZUUHYBWMWJHK-UHFFFAOYSA-N [Co].[Ni] Chemical compound [Co].[Ni] QXZUUHYBWMWJHK-UHFFFAOYSA-N 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 2
- 239000004480 active ingredient Substances 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000008135 aqueous vehicle Substances 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 2
- 229910002113 barium titanate Inorganic materials 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 229910001431 copper ion Inorganic materials 0.000 description 2
- HFDWIMBEIXDNQS-UHFFFAOYSA-L copper;diformate Chemical compound [Cu+2].[O-]C=O.[O-]C=O HFDWIMBEIXDNQS-UHFFFAOYSA-L 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 2
- JRBPAEWTRLWTQC-UHFFFAOYSA-N dodecylamine Chemical compound CCCCCCCCCCCCN JRBPAEWTRLWTQC-UHFFFAOYSA-N 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- IIEWJVIFRVWJOD-UHFFFAOYSA-N ethylcyclohexane Chemical compound CCC1CCCCC1 IIEWJVIFRVWJOD-UHFFFAOYSA-N 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000007646 gravure printing Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 239000012770 industrial material Substances 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- UAEPNZWRGJTJPN-UHFFFAOYSA-N methylcyclohexane Chemical compound CC1CCCCC1 UAEPNZWRGJTJPN-UHFFFAOYSA-N 0.000 description 2
- 229940078494 nickel acetate Drugs 0.000 description 2
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 2
- BMGNSKKZFQMGDH-FDGPNNRMSA-L nickel(2+);(z)-4-oxopent-2-en-2-olate Chemical compound [Ni+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O BMGNSKKZFQMGDH-FDGPNNRMSA-L 0.000 description 2
- HZPNKQREYVVATQ-UHFFFAOYSA-L nickel(2+);diformate Chemical compound [Ni+2].[O-]C=O.[O-]C=O HZPNKQREYVVATQ-UHFFFAOYSA-L 0.000 description 2
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 2
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 2
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 2
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 description 2
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 239000002798 polar solvent Substances 0.000 description 2
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 2
- 229920002635 polyurethane Polymers 0.000 description 2
- 239000004814 polyurethane Substances 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229940116411 terpineol Drugs 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 239000003643 water by type Substances 0.000 description 2
- WUOACPNHFRMFPN-SECBINFHSA-N (S)-(-)-alpha-terpineol Chemical compound CC1=CC[C@@H](C(C)(C)O)CC1 WUOACPNHFRMFPN-SECBINFHSA-N 0.000 description 1
- NKJOXAZJBOMXID-UHFFFAOYSA-N 1,1'-Oxybisoctane Chemical compound CCCCCCCCOCCCCCCCC NKJOXAZJBOMXID-UHFFFAOYSA-N 0.000 description 1
- FJLUATLTXUNBOT-UHFFFAOYSA-N 1-Hexadecylamine Chemical compound CCCCCCCCCCCCCCCCN FJLUATLTXUNBOT-UHFFFAOYSA-N 0.000 description 1
- HBNHCGDYYBMKJN-UHFFFAOYSA-N 2-(4-methylcyclohexyl)propan-2-yl acetate Chemical compound CC1CCC(C(C)(C)OC(C)=O)CC1 HBNHCGDYYBMKJN-UHFFFAOYSA-N 0.000 description 1
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 description 1
- FERIUCNNQQJTOY-UHFFFAOYSA-M Butyrate Chemical compound CCCC([O-])=O FERIUCNNQQJTOY-UHFFFAOYSA-M 0.000 description 1
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Natural products CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 description 1
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- DQEFEBPAPFSJLV-UHFFFAOYSA-N Cellulose propionate Chemical compound CCC(=O)OCC1OC(OC(=O)CC)C(OC(=O)CC)C(OC(=O)CC)C1OC1C(OC(=O)CC)C(OC(=O)CC)C(OC(=O)CC)C(COC(=O)CC)O1 DQEFEBPAPFSJLV-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
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- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- REYJJPSVUYRZGE-UHFFFAOYSA-N Octadecylamine Chemical compound CCCCCCCCCCCCCCCCCCN REYJJPSVUYRZGE-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- UWHCKJMYHZGTIT-UHFFFAOYSA-N Tetraethylene glycol, Natural products OCCOCCOCCOCCO UWHCKJMYHZGTIT-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- OVKDFILSBMEKLT-UHFFFAOYSA-N alpha-Terpineol Natural products CC(=C)C1(O)CCC(C)=CC1 OVKDFILSBMEKLT-UHFFFAOYSA-N 0.000 description 1
- 229940088601 alpha-terpineol Drugs 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
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- LSIWWRSSSOYIMS-UHFFFAOYSA-L copper;diformate;tetrahydrate Chemical compound O.O.O.O.[Cu+2].[O-]C=O.[O-]C=O LSIWWRSSSOYIMS-UHFFFAOYSA-L 0.000 description 1
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
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- 229920000609 methyl cellulose Polymers 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
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- XTAZYLNFDRKIHJ-UHFFFAOYSA-N n,n-dioctyloctan-1-amine Chemical compound CCCCCCCCN(CCCCCCCC)CCCCCCCC XTAZYLNFDRKIHJ-UHFFFAOYSA-N 0.000 description 1
- SMAMDWMLHWVJQM-UHFFFAOYSA-L nickel(2+);diformate;dihydrate Chemical compound O.O.[Ni+2].[O-]C=O.[O-]C=O SMAMDWMLHWVJQM-UHFFFAOYSA-L 0.000 description 1
- JMWUYEFBFUCSAK-UHFFFAOYSA-L nickel(2+);octadecanoate Chemical compound [Ni+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O JMWUYEFBFUCSAK-UHFFFAOYSA-L 0.000 description 1
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- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
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- 239000004014 plasticizer Substances 0.000 description 1
- CLSUSRZJUQMOHH-UHFFFAOYSA-L platinum dichloride Chemical compound Cl[Pt]Cl CLSUSRZJUQMOHH-UHFFFAOYSA-L 0.000 description 1
- 229920000083 poly(allylamine) Polymers 0.000 description 1
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- 229910052700 potassium Inorganic materials 0.000 description 1
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical group [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Description
本発明は、例えば積層セラミックコンデンサ（ＭＬＣＣ）の内部電極材料、電力用半導体素子の接合材料などの用途に利用できるニッケル粒子、並びに、それを用いた、導電性ペースト、内部電極及び積層セラミックコンデンサに関する。 The present invention relates to nickel particles that can be used, for example, as an internal electrode material for a multilayer ceramic capacitor (MLCC), a bonding material for a power semiconductor element, and a conductive paste, an internal electrode, and a multilayer ceramic capacitor using the same. ..
金属微粒子は、バルク金属とは異なる物理的・化学的特性を有することから、例えば、導電性ペーストや透明導電膜などの電極材料、高密度記録材料、触媒材料、インクジェット用インク材料等の様々な工業材料に利用されている。近年では、電子機器の小型化や薄型化に伴い、金属微粒子も、数十〜数百ｎｍ程度まで微粒子化が進んでいる。 Since metal fine particles have different physical and chemical properties from bulk metals, various materials such as electrode materials such as conductive pastes and transparent conductive films, high-density recording materials, catalyst materials, and ink materials for inkjets are used. It is used as an industrial material. In recent years, as electronic devices have become smaller and thinner, metal fine particles have also been made into fine particles of several tens to several hundreds of nm.
例えば、電子機器の小型化に伴い、積層セラミックコンデンサ（ＭＬＣＣ）の電極は薄膜多層化が進んでいる。このことに伴い、電極層の材料には、例えば平均粒子径が１５０ｎｍを下回る程度に小さく、粒子径が均一で、そのばらつきが小さく、かつ、出来るだけ分散性に優れたナノ粒子が好ましいと考えられている。なぜなら、平均粒子径と比較して極端に大きい粗大粒子が含まれていたり、その量が多かったりすると、電極層の厚みが均一でない、粗大粒子が誘電体層を貫通して隣接する内部電極層と接触し、ショートによる製品不良、または信頼性及び寿命低下、または十分な容量が得られなくなる、等の問題が起こる恐れがあるからである。 For example, with the miniaturization of electronic devices, the electrodes of multilayer ceramic capacitors (MLCCs) are becoming thin and multi-layered. Along with this, it is considered preferable that the material of the electrode layer is nanoparticles having an average particle diameter as small as less than 150 nm, a uniform particle diameter, a small variation thereof, and excellent dispersibility as much as possible. Has been done. This is because if coarse particles that are extremely large compared to the average particle diameter are contained or the amount is large, the thickness of the electrode layer is not uniform, and the coarse particles penetrate the dielectric layer and are adjacent to the internal electrode layer. This is because there is a risk that the product may be defective due to a short circuit, the reliability and life may be shortened, or a sufficient capacity may not be obtained.
粒子形状、粒子径が揃っており、二次凝集が少ない金属微粒子を製造する方法として、例えば特許文献１では、金属塩の溶液に還元剤を添加することにより、独立単分散状態にある金属超微粒子（核）を生成させる工程と、この核に、還元剤の存在下、金属塩の溶液から金属を還元析出させる工程を含む多段階の製造方法が提案されている。 As a method for producing metal fine particles having the same particle shape and particle size and less secondary aggregation, for example, in Patent Document 1, by adding a reducing agent to a solution of a metal salt, a metal super in an independent monodisperse state is obtained. A multi-step production method including a step of generating fine particles (nucleus) and a step of reducing and precipitating a metal from a solution of a metal salt in the presence of a reducing agent has been proposed.
また、異種金属のコアとシェルを含む金属微粒子の多段階製造方法として、例えば特許文献２では、ニッケル粒子、コバルト塩および１級アミンを含む混合物を加熱して錯化反応液を得る工程と、この錯化反応液を加熱してニッケル−コバルトナノ粒子スラリーを得る工程と、を含むニッケル−コバルトナノ粒子の製造方法が提案されている。 Further, as a multi-step production method of metal fine particles containing a dissimilar metal core and shell, for example, in Patent Document 2, a step of heating a mixture containing nickel particles, a cobalt salt and a primary amine to obtain a complexing reaction solution is used. A method for producing nickel-cobalt nanoparticles including a step of heating this complexing reaction solution to obtain a nickel-cobalt nanoparticles slurry has been proposed.
特許文献１の実施例では、核となる金属超微粒子の大きさが１００ｎｍを超えており、最終的に製造される金属微粒子の平均粒子径も１μｍ程度であることから、凝集が発生しにくく、粒子径のばらつきに対する許容範囲も広い。そのため、特許文献１の技術は、現在の工業材料に求められる、例えば平均粒子径が１５０ｎｍ以下の小さな金属微粒子の製造に適用できるものではない。 In the examples of Patent Document 1, since the size of the core metal ultrafine particles exceeds 100 nm and the average particle size of the finally produced metal fine particles is about 1 μm, aggregation is unlikely to occur. The permissible range for variations in particle size is also wide. Therefore, the technique of Patent Document 1 is not applicable to the production of small metal fine particles having an average particle diameter of 150 nm or less, which are required for current industrial materials.
また、平均粒子径が１５０ｎｍ以下の金属微粒子では、例えばニッケルなどの磁性材料を主成分とする場合、磁性によって凝集が生じやすくなり、分散性が低下することが懸念される。しかしながら、磁性材料を主要な成分とする金属微粒子において、磁性による分散性への影響を考慮した粒子設計はこれまでなされていない。 Further, in the case of metal fine particles having an average particle diameter of 150 nm or less, when a magnetic material such as nickel is used as a main component, there is a concern that agglomeration is likely to occur due to magnetism and the dispersibility is lowered. However, in metal fine particles containing a magnetic material as a main component, no particle design has been made in consideration of the influence of magnetism on the dispersibility.
本発明の目的は、平均粒子径が１５０ｎｍ以下であり、粒子径が均一でそのばらつきが小さく、かつ分散性に優れた金属微粒子を提供することである。 An object of the present invention is to provide metal fine particles having an average particle size of 150 nm or less, a uniform particle size, a small variation thereof, and excellent dispersibility.
上記課題を解決するため、本発明のニッケル粒子は、金属元素成分の含有量が９０〜９９質量％であり、前記金属元素以外の成分の含有量が１〜１０質量％であるニッケル粒子であって、
走査型電子顕微鏡観察により測定された、前記ニッケル粒子の一次粒子の平均粒子径Ｄ５０が２０ｎｍ〜１５０ｎｍであり、一次粒子径の変動係数が、０．２以下であり、前記平均粒子径Ｄ５０の２．０倍以上の粒子が、全粒子個数の０．１％以下である、
を備えている。
In order to solve the above problems, the nickel particles of the present invention are nickel particles having a metal element component content of 90 to 99% by mass and a component other than the metal element content of 1 to 10% by mass. hand,
The average particle size D 50 of the primary particles of the nickel particles measured by scanning electron microscope observation is 20 nm to 150 nm, the coefficient of variation of the primary particle size is 0.2 or less, and the average particle size D 50. 2.0 times or more of the total number of particles is 0.1% or less.
Is equipped with.
また、本発明のニッケル粒子は、前記金属元素成分が、ニッケル、又は、ニッケル及び銅であってもよい。 Further, in the nickel particles of the present invention, the metal element component may be nickel, or nickel and copper.
また、本発明のニッケル粒子は、前記金属元素成分において、ニッケル及び銅の質量比（ニッケル：銅）が、９９．９９〜８０．００：０．０１〜２０．００であってもよい。 Further, the nickel particles of the present invention may have a mass ratio of nickel to copper (nickel: copper) of 99.99 to 80.00: 0.01 to 20.00 in the metal element component.
また、本発明のニッケル粒子は、前記一次粒子の平均粒子径Ｄ５０が３０〜１００ｎｍであってもよい。 Further, the nickel particles of the present invention may have an average particle diameter D 50 of the primary particles of 30 to 100 nm.
また、本発明のニッケル粒子は、前記金属元素以外の成分が、炭素、窒素、水素、酸素、硫黄及びリンからなる群から選ばれたいずれか１種又は２種以上であってもよい。 Further, the nickel particles of the present invention may contain any one or more components other than the metal element selected from the group consisting of carbon, nitrogen, hydrogen, oxygen, sulfur and phosphorus.
また、本発明のニッケル粒子は、その表面に、アミン化合物、アミド化合物及びニトリル化合物からなる群から選ばれたいずれか１種又は２種以上が付着していてもよい。 Further, the nickel particles of the present invention may have any one or more selected from the group consisting of amine compounds, amide compounds and nitrile compounds attached to the surface thereof.
また、本発明のニッケル粒子は、還元雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、６００℃〜１０００℃における重量減少率が、０．１％未満であってもよい。 Further, the nickel particles of the present invention have a weight loss rate of less than 0.1% at 600 ° C. to 1000 ° C. when the temperature is raised from 25 ° C. at a heating rate of 15 ° C./min under a reducing atmosphere. There may be.
また、本発明のニッケル粒子は、不活性雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、２００℃〜４００℃における重量減少率が、２５℃〜１０００℃における重量減少率の５０％〜７０％であり、かつ、還元雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、２５℃〜３００℃の重量減少率が、２５℃〜１０００℃における重量減少率の８５％以上であってもよい。 Further, the nickel particles of the present invention have a weight loss rate of 25 ° C. to 1000 ° C. at 200 ° C. to 400 ° C. when the temperature is raised from 25 ° C. at a temperature rising rate of 15 ° C./min in an inert atmosphere. The weight loss rate of 25 ° C. to 300 ° C. is 50% to 70% of the weight loss rate in the above, and when the temperature is raised from 25 ° C. to a temperature rise rate of 15 ° C./min in a reducing atmosphere. It may be 85% or more of the weight loss rate at 25 ° C. to 1000 ° C.
本発明の導電性ペーストは、上記いずれかのニッケル粒子を含有する。 The conductive paste of the present invention contains any of the above nickel particles.
本発明の積層セラミックコンデンサ用の内部電極は、上記いずれかのニッケル粒子をペースト化し、セラミック基板上に印刷したものである。 The internal electrode for the multilayer ceramic capacitor of the present invention is obtained by pasting any of the above nickel particles and printing them on a ceramic substrate.
本発明の積層セラミックコンデンサは、上記内部電極とセラミック誘電体とを交互に層状に重ねて圧着し、焼成して一体化させたものである。 In the multilayer ceramic capacitor of the present invention, the internal electrodes and ceramic dielectrics are alternately layered and pressure-bonded, fired and integrated.
本発明のニッケル粒子は、その一次粒子の平均粒子径Ｄ５０が１５０ｎｍ以下であり、一次粒子径の変動係数が、０．２以下であるため、粒子径が均一でそのばらつきが小さく、かつ分散性に優れている。特に、前記平均粒子径Ｄ５０の２．０倍以上の粒子が、全粒子個数の０．１％以下であるため、粗大粒子が極めて少ない。そのため、このニッケル粒子は、例えばＭＬＣＣの内部電極材料、電力用半導体素子の接合材料などの用途として好適に利用できる。また、本発明の内部電極を用いたＭＬＣＣは、従来のニッケル粒子を使用した電極の膜厚をより薄くすることが可能であることから、小型高容量を実現でき、長寿命性、高信頼性に優れる。そのため、携帯電話、携帯端末、パーソナルコンピュータ、ドローンやスマートウオッチ等の電気・電子製品、オーディオ、通信、コンピュータ制御等の自動車用部品に好適に用いることができる。 Since the average particle diameter D 50 of the primary particles of the nickel particles of the present invention is 150 nm or less and the coefficient of variation of the primary particle diameter is 0.2 or less, the particle diameter is uniform, the variation is small, and the particles are dispersed. Excellent in sex. In particular, since the number of particles 2.0 times or more the average particle diameter D 50 is 0.1% or less of the total number of particles, the number of coarse particles is extremely small. Therefore, the nickel particles can be suitably used, for example, as an internal electrode material for MLCCs and a bonding material for power semiconductor elements. Further, the MLCC using the internal electrode of the present invention can realize a small size and a high capacity because the film thickness of the electrode using the conventional nickel particles can be made thinner, and has a long life and high reliability. Excellent for. Therefore, it can be suitably used for mobile phones, mobile terminals, personal computers, electric / electronic products such as drones and smart watches, and automobile parts such as audio, communication, and computer control.
［ニッケル粒子］
本実施の形態に係るニッケル粒子は、下記の構成ａ〜ｄを備えている。
＜構成ａ＞
本実施の形態に係るニッケル粒子は、ニッケル元素を主成分とする金属元素成分の含有量が８５〜９９質量％であり、前記金属元素以外の成分の含有量が１〜１５質量％である。好ましくは、金属元素成分の含有量が９０〜９８質量％であり、前記金属元素以外の成分の含有量が２〜１０質量％である。
ここで、「ニッケル元素を主成分とする」とは、金属元素成分中、ニッケル元素を８０重量％以上、より好ましくは９０重量％以上、さらに好ましくは９０重量％以上９９．９重量％以下の範囲内で含有することを意味する。本実施の形態に係るニッケル粒子は、ニッケル以外の金属を含有していてもよい。そのような金属としては、例えば、チタン、コバルト、クロム、マンガン、鉄、アルミニウム、ナトリウム、カリウム、マグネシウム、ジルコニウム、スズ、タングステン、モリブデン、バナジウム、バリウム、カルシウム、ストロンチウム。シリコン、アルミニウム、リン等の卑金属、金、銀、白金、パラジウム、イリジウム、オスミウム、ルテニウム、ロジウム、レニウム、ネオジウム、ニオブ、ホロニウム、ディスプロヂウム、イットリウム等の貴金属、希土類金属を挙げることができる。これらのニッケル以外の金属は、単独でもよく、又は２種以上含有していてもよい。好ましくは、「粗大粒子が極めて少なく、粒度分布のシャープな粒子を合成しやすい」などいう理由から、銅、銀、金、白金又はパラジウムであり、より好ましくは、銅である。ニッケル以外の金属として、銅を含有する場合、ニッケル及び銅の質量比（ニッケル：銅）が、９９．９９〜８０．００：０．０１〜２０．００であることが好ましい。より好ましくは、９９．９９〜９８．００：０．０１〜２．００である。さらに好ましくは、９９．９９〜９８．５０：０．０１〜１．５０である。銅、銀、金、白金又はパラジウムを含有する場合、上記の銅、銀、金、白金又はパラジウム以外の金属を、さらに含有しても良い。前記ニッケル以外の金属は、凝集の原因となるニッケル粒子の磁性を弱め、分散性の向上に寄与する。従って、例えばニッケル元素に対する銅元素の含有割合が０．０１質量％未満であると、分散性の改善効果が得られない。一方、２０質量％を超えると、加熱還元による粒子成長の効率が悪くなる。マイクロ波による加熱還元をする場合は、マイクロ波を吸収し難くなるため、効率の悪化が特に顕著である。また、前記ニッケル以外の金属として銅を用いた場合は、銅元素の存在による粒子の酸化安定性の低下が生じ、さらには、ＭＬＣＣの内部電極用の導電性ペースト材料として用いる場合に、脱バインダー工程において、銅の酸化が急速に起こり、クラックや層間剥離などの不具合が発生しやすくなる。
また、金属元素以外の成分としては、炭素、窒素、水素、酸素、硫黄及びリンからなる群から選ばれたいずれか１種又は２種以上が挙げられる。好ましくは、炭素、窒素、水素又は酸素である。これらの金属元素以外の成分を含むことで、ニッケル粒子において、良好な分散性を発現する。より好ましくは、炭素が０．１質量％〜８質量％、窒素が０．００１質量％〜０．５質量％、水素が０．０１質量％〜１質量％、酸素が０．１質量％〜１０質量％である。さらに好ましくは、炭素が０．１質量％〜５質量％、窒素が０．００１質量％〜０．３質量％、水素が０．０５質量％〜０．７質量％、酸素が０．１質量％〜７質量％である。さらに好ましくは、炭素が０．５質量％〜４質量％、窒素が０．０１質量％〜０．２質量％、水素が０．０５質量％〜０．５質量％、酸素が０．５質量％〜５質量％である。
これらの金属元素以外の成分として、前記ニッケル粒子の表面に、アミン化合物、アミド化合物及びニトリル化合物からなる群から選ばれたいずれか１種又は２種以上が付着していることが、ニッケル粒子において、良好な分散性を発現するため好ましい。より好ましくは、炭素数１〜２０のアルキル基を含む、アミン化合物、アミド化合物又はニトリル化合物からなる群から選ばれたいずれか１種又は２種以上である。また、これらの化合物の他に、これらの化合物同士の反応物や重合物が含まれていても良い。これらの化合物の含有量は、これらの化合物の合計量として、０．１質量％〜５．０質量％であることが好ましく、より好ましくは、０．３質量％〜４．０質量％である。
[Nickel particles]
The nickel particles according to the present embodiment have the following configurations a to d.
<Structure a>
The nickel particles according to the present embodiment have a content of a metal element component containing a nickel element as a main component of 85 to 99% by mass, and a content of a component other than the metal element of 1 to 15% by mass. Preferably, the content of the metal element component is 90 to 98% by mass, and the content of the component other than the metal element is 2 to 10% by mass.
Here, "mainly composed of nickel element" means that the nickel element is 80% by weight or more, more preferably 90% by weight or more, still more preferably 90% by weight or more and 99.9% by weight or less in the metal element component. It means that it is contained within the range. The nickel particles according to the present embodiment may contain a metal other than nickel. Such metals include, for example, titanium, cobalt, chromium, manganese, iron, aluminum, sodium, potassium, magnesium, zirconium, tin, tungsten, molybdenum, vanadium, barium, calcium, strontium. Examples include base metals such as silicon, aluminum and phosphorus, precious metals such as gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, rhenium, neodium, niobium, holonium, disprodium and ittrium, and rare earth metals. These metals other than nickel may be used alone or may contain two or more kinds of metals. Copper, silver, gold, platinum or palladium is preferable, and copper is more preferable, for the reason that "there are very few coarse particles and it is easy to synthesize particles having a sharp particle size distribution". When copper is contained as a metal other than nickel, the mass ratio of nickel to copper (nickel: copper) is preferably 99.99 to 80.00: 0.01 to 20.00. More preferably, it is 99.99 to 98.00: 0.01 to 2.00. More preferably, it is 99.99 to 98.50: 0.01 to 1.50. When copper, silver, gold, platinum or palladium is contained, a metal other than the above-mentioned copper, silver, gold, platinum or palladium may be further contained. The metal other than nickel weakens the magnetism of the nickel particles that cause agglomeration and contributes to the improvement of dispersibility. Therefore, for example, if the content ratio of the copper element to the nickel element is less than 0.01% by mass, the effect of improving the dispersibility cannot be obtained. On the other hand, if it exceeds 20% by mass, the efficiency of particle growth due to heat reduction deteriorates. In the case of heat reduction by microwaves, it becomes difficult to absorb microwaves, so that the deterioration of efficiency is particularly remarkable. Further, when copper is used as a metal other than nickel, the oxidation stability of the particles is lowered due to the presence of the copper element, and further, when it is used as a conductive paste material for the internal electrode of MLCC, the binder is removed. In the process, copper is rapidly oxidized, and defects such as cracks and delamination are likely to occur.
In addition, examples of components other than metal elements include any one or more selected from the group consisting of carbon, nitrogen, hydrogen, oxygen, sulfur and phosphorus. Preferred are carbon, nitrogen, hydrogen or oxygen. By containing components other than these metal elements, good dispersibility is exhibited in nickel particles. More preferably, carbon is 0.1% by mass to 8% by mass, nitrogen is 0.001% by mass to 0.5% by mass, hydrogen is 0.01% by mass to 1% by mass, and oxygen is 0.1% by mass to 0.1% by mass. It is 10% by mass. More preferably, carbon is 0.1% by mass to 5% by mass, nitrogen is 0.001% by mass to 0.3% by mass, hydrogen is 0.05% by mass to 0.7% by mass, and oxygen is 0.1% by mass. % To 7% by mass. More preferably, carbon is 0.5% by mass to 4% by mass, nitrogen is 0.01% by mass to 0.2% by mass, hydrogen is 0.05% by mass to 0.5% by mass, and oxygen is 0.5% by mass. % To 5% by mass.
As a component other than these metal elements, one or more selected from the group consisting of amine compounds, amide compounds and nitrile compounds is attached to the surface of the nickel particles in the nickel particles. , It is preferable because it exhibits good dispersibility. More preferably, any one or more selected from the group consisting of amine compounds, amide compounds and nitrile compounds containing an alkyl group having 1 to 20 carbon atoms. Further, in addition to these compounds, a reactant or a polymer of these compounds may be contained. The content of these compounds is preferably 0.1% by mass to 5.0% by mass, more preferably 0.3% by mass to 4.0% by mass, as the total amount of these compounds. ..
＜構成ｂ＞
本実施の形態に係るニッケル粒子は、走査型電子顕微鏡（ＳＥＭ）により測定された、前記ニッケル粒子の一次粒子の平均粒子径Ｄ５０（以下、単に「平均粒子径」ともいう。）が２０ｎｍ〜１５０ｎｍである。好ましくは、３０ｎｍ〜１００ｎｍであり、より好ましくは、４０ｎｍ〜１００ｎｍである。ニッケル粒子の平均粒子径が２０ｎｍ未満であると、相対的にニッケル以外の金属の含有量が多くなり、加熱還元による粒子成長の効率が悪くなる、熱収縮率が大きくなる、（ニッケル以外の金属として銅を使用した場合、）酸化しやすくなる等の問題が起こり得る。マイクロ波による加熱還元をする場合は、マイクロ波を吸収し難くなるため、効率の悪化が特に顕著である。
また、平均粒子径が２０ｎｍ未満では凝集しやすくなり、例えばＭＬＣＣの内部電極材料用の導電性ペーストとして用いる場合に、導電性ペーストの作製が困難になるばかりでなく、誘電体層の積層後の焼成時に誘電体との収縮率差が大きくなり、クラック等の問題が生じやすい。一方、ニッケル粒子の平均粒子径が１５０ｎｍを超えると、例えばＭＬＣＣの内部電極材料用の導電性ペーストとして用いる場合に、電極層の表面に凹凸が発生し、電極層の薄層化及び多層化が困難になったり、電気的特性を低下させたりする原因となるなど、微細化への対応が困難になる。
<Structure b>
Nickel particles according to the present embodiment was measured by a scanning electron microscope (SEM), the average particle diameter D 50 of the primary particles of the nickel particles (hereinafter, simply referred to as "average particle diameter".) Is 20nm~ It is 150 nm. It is preferably 30 nm to 100 nm, and more preferably 40 nm to 100 nm. When the average particle size of nickel particles is less than 20 nm, the content of metals other than nickel is relatively large, the efficiency of particle growth due to heat reduction is lowered, and the heat shrinkage rate is increased (metals other than nickel). When copper is used as a metal, problems such as easy oxidation may occur. In the case of heat reduction by microwaves, it becomes difficult to absorb microwaves, so that the deterioration of efficiency is particularly remarkable.
Further, if the average particle size is less than 20 nm, agglomeration is likely to occur. For example, when used as a conductive paste for an internal electrode material of MLCC, not only is it difficult to prepare the conductive paste, but also after the dielectric layers are laminated, it becomes difficult to prepare the conductive paste. During firing, the difference in shrinkage rate from the dielectric becomes large, and problems such as cracks are likely to occur. On the other hand, when the average particle size of the nickel particles exceeds 150 nm, irregularities occur on the surface of the electrode layer when used as a conductive paste for an internal electrode material of MLCC, and the electrode layer becomes thin and multi-layered. It becomes difficult to deal with miniaturization, which causes difficulty and deterioration of electrical characteristics.
本実施の形態に係るニッケル粒子は、例えば球状、擬球状、長球状、立方体様、切頭四面体様、双角錐状、正八面体様、正十面体様、正二十面体様等の種々の形状であってよいが、例えばニッケル粒子を電子部品の電極に使用した場合の充填密度の向上という観点から、球状又は擬球状が好ましく、球状がより好ましい。ここで、ニッケル粒子の形状は、例えば、ＳＥＭで観察することにより確認できる。また、ニッケル粒子の平均粒子径は、ＳＥＭにより試料の写真を撮影して、その中から無作為に１０００個〜１０００００個を抽出してそれぞれの粒子について面積を求め、真球に換算したときの粒子径から、個数基準にて求めることができる。 The nickel particles according to the present embodiment include various types such as spherical, pseudospherical, oblong spherical, cubic, truncated tetrahedron, bipyramid, regular octahedron, regular dodecahedron, and regular dodecahedron. Although it may have a shape, it is preferably spherical or pseudo-spherical, and more preferably spherical, for example, from the viewpoint of improving the packing density when nickel particles are used for the electrodes of electronic parts. Here, the shape of the nickel particles can be confirmed by, for example, observing with an SEM. In addition, the average particle size of nickel particles is when a sample photograph is taken by SEM, 1000 to 100,000 particles are randomly selected from the sample, the area of each particle is calculated, and converted into a true sphere. It can be obtained from the particle size on the basis of the number of particles.
＜構成ｃ＞
本実施の形態に係るニッケル粒子は、走査型電子顕微鏡により測定された、一次粒子径の変動係数（標準偏差／平均粒子径；ＣＶ値）が、０．２以下である。ＣＶ値が０．２を超えると、例えばＭＬＣＣの内部電極用の導電性ペースト材料として用いる場合に、電極層の表面に凹凸が発生し、電極層の薄層化及び多層化が困難になったり、電気的特性を低下させたりする原因となることがある。
<Structure c>
The nickel particles according to the present embodiment have a coefficient of variation (standard deviation / average particle size; CV value) of the primary particle size measured by a scanning electron microscope of 0.2 or less. When the CV value exceeds 0.2, for example, when used as a conductive paste material for the internal electrode of MLCC, unevenness is generated on the surface of the electrode layer, and it becomes difficult to make the electrode layer thin and multi-layered. , May cause deterioration of electrical characteristics.
＜構成ｄ＞
本実施の形態に係るニッケル粒子は、走査型電子顕微鏡により測定された、平均粒子径Ｄ５０の２．０倍以上の粒子が、全粒子個数の０．１％以下である。好ましくは、０．０１％以下である。ここで、平均粒子径Ｄ５０の２．０倍以上の粒子（以下、「粗大粒子」ともいう。）が０．１％を超えると、例えばＭＬＣＣの内部電極用の導電性ペースト材料として用いる場合に、電極層の表面に凹凸が発生し、電極層の薄層化及び多層化が困難になったり、電気的特性を低下させたりする原因となることがある。粗大粒子は、平均粒子径と比較して極端に大きいため、電極層の厚みのばらつきや、粗大粒子が誘電体層を貫通して隣接する内部電極層と接触し、ショートによる製品不良、または信頼性及び寿命低下、または十分な容量が得られなくなる、等の問題を引き起こす傾向にあるため、できるだけ少ない方が好ましい。
<Structure d>
As for the nickel particles according to the present embodiment, the particles having an average particle diameter D of 50 or more as measured by a scanning electron microscope are 0.1% or less of the total number of particles. Preferably, it is 0.01% or less. Here, when particles (hereinafter, also referred to as “coarse particles”) 2.0 times or more the average particle diameter D 50 exceed 0.1%, for example, when used as a conductive paste material for an internal electrode of MLCC. In addition, the surface of the electrode layer may have irregularities, which may make it difficult to thin or multi-layer the electrode layer, or may cause deterioration of electrical characteristics. Since the coarse particles are extremely large compared to the average particle size, the thickness of the electrode layer varies, and the coarse particles penetrate the dielectric layer and come into contact with the adjacent internal electrode layer, resulting in product failure or reliability due to a short circuit. It tends to cause problems such as deterioration of properties and life, or insufficient capacity, so it is preferable to reduce the number as much as possible.
また、ＭＬＣＣの製造工程では、酸化反応や還元反応によってニッケル粒子が膨張・収縮して体積変化が生じる。また、セラミックス誘電体も焼結により膨張・収縮し、体積変化が生じる。ところが、ニッケル粒子とセラミックス誘電体とでは、焼結時における膨張・収縮による体積変化の挙動が異なる。すなわち、ニッケル粒子の焼結開始温度（約５００℃）とセラミックス誘電体の焼結開始温度（約１０００℃）が大きく異なるために、デラミネーションやクラック等の欠陥を生じるおそれがある。特に、粒子径が１５０ｎｍ以下のニッケル粒子は、ＭＬＣＣ製造時の焼結過程で誘電体層との熱収縮の差が従来の大粒子径のニッケル粒子に比べてより拡大し、内部電極層と誘電体層とのデラミネーションや内部電極層の膜切れが多くなり、やはり製品としての歩留まりに問題があった。
従って、ニッケル粒子は、特に、焼結開始温度以上の高温領域における熱収縮が小さい方が好ましい。その観点で、本実施の形態に係るニッケル粒子は、還元雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、６００℃〜１０００℃における重量減少率が、０．１％未満であることが好ましい。より好ましくは、０％以下（つまり、０％又はマイナスの値）であることが、より好ましい。ここで、マイナスの値である場合、６００℃〜１０００℃において重量が増加していることを意味する。
また、本実施の形態に係るニッケル粒子は、不活性雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、２００℃〜４００℃における重量減少率が、２５℃〜１０００℃における重量減少率の５０％〜７０％であり、かつ、還元雰囲気下で、２５℃から、昇温速度１５℃／分で昇温させた際の、２５℃〜３００℃の重量減少率が、２５℃〜１０００℃における重量減少率の８５％以上であることが好ましい。
詳細は明らかではないが、本実施の形態に係るニッケル粒子は、６００℃以下で、金属元素以外の成分の大部分が除去されるため、従来のニッケル粒子と比較して、特に６００℃以上の高温領域における熱収縮が抑えられていると考えられる。
Further, in the MLCC manufacturing process, nickel particles expand and contract due to an oxidation reaction or a reduction reaction to cause a volume change. In addition, the ceramic dielectric also expands and contracts due to sintering, causing a volume change. However, the behavior of volume change due to expansion and contraction during sintering differs between nickel particles and ceramic dielectrics. That is, since the sintering start temperature (about 500 ° C.) of the nickel particles and the sintering start temperature (about 1000 ° C.) of the ceramic dielectric are significantly different, defects such as delamination and cracks may occur. In particular, nickel particles having a particle size of 150 nm or less have a larger difference in thermal shrinkage from the dielectric layer during the sintering process during the production of MLCC, and the difference between the internal electrode layer and the dielectric layer is larger than that of the conventional large particle size nickel particles. Delamination with the body layer and film breakage of the internal electrode layer increased, and there was also a problem in the yield as a product.
Therefore, it is preferable that the nickel particles have a small heat shrinkage in a high temperature region equal to or higher than the sintering start temperature. From this point of view, the nickel particles according to the present embodiment have a weight loss rate of 0 at 600 ° C. to 1000 ° C. when the temperature is raised from 25 ° C. at a temperature rising rate of 15 ° C./min under a reducing atmosphere. It is preferably less than 1%. More preferably, it is 0% or less (that is, 0% or a negative value). Here, when it is a negative value, it means that the weight is increased at 600 ° C. to 1000 ° C.
Further, the nickel particles according to the present embodiment have a weight loss rate of 25 ° C. at 200 ° C. to 400 ° C. when the temperature is raised from 25 ° C. at a temperature rising rate of 15 ° C./min in an inert atmosphere. Weight loss of 25 ° C. to 300 ° C. when the temperature is 50% to 70% of the weight loss rate at ~ 1000 ° C. and the temperature is raised from 25 ° C. at a heating rate of 15 ° C./min under a reducing atmosphere. The rate is preferably 85% or more of the weight loss rate at 25 ° C. to 1000 ° C.
Although the details are not clear, the nickel particles according to the present embodiment have a temperature of 600 ° C. or lower, and most of the components other than the metal elements are removed. Therefore, the nickel particles have a temperature of 600 ° C. or higher as compared with the conventional nickel particles. It is considered that the heat shrinkage in the high temperature region is suppressed.
［導電性ペースト］
本実施の形態に係る導電性ペーストは、上記構成ａ〜ｄを備えたニッケル粒子及び有機ビヒクルを含有する。
[Conductive paste]
The conductive paste according to the present embodiment contains nickel particles and an organic vehicle having the above configurations a to d.
＜有機ビヒクル＞
本実施の形態で用いる有機ビヒクルとしては、例えば有機溶媒、有機バインダー、非水系高分子分散剤などを含むことができる。
<Organic vehicle>
The organic vehicle used in the present embodiment may include, for example, an organic solvent, an organic binder, a non-aqueous polymer dispersant, and the like.
（有機溶媒）
例えば水と混和しない有機溶媒として、トルエン、キシレン、エチルベンゼン等の芳香族系炭化水素系、ヘキサン、ヘプタン、デカン、オクタン、ヘプタン、シクロヘキサン、メチルシクロヘキサン、エチルシクロヘキサン等の脂肪族系炭化水素系、酢酸エチル、酢酸ブチル、ジヒドロターピニルアセテート、イソボニルアセテート、イソボニルプロキネート、イソボニルブチレート、イソボニルイソブチレート等のエステル系、α−テルピネオール、ブチルカルビトール等の長鎖アルコール系、長鎖アルコールとカルボン酸とのエステル等が挙げられる。また、上記の有機溶媒の他に、一部が水と混和する有機溶媒、例えばアセトン、メチルエチルケトン、メチルイソブチルケトン等のケトン系も使用可能である。
(Organic solvent)
For example, as an organic solvent immiscible with water, aromatic hydrocarbons such as toluene, xylene and ethylbenzene, aliphatic hydrocarbons such as hexane, heptane, decane, octane, heptane, cyclohexane, methylcyclohexane and ethylcyclohexane, and acetates. Esters such as ethyl, butyl acetate, dihydroterpinyl acetate, isobonyl acetate, isobonyl propylate, isobonyl butyrate, isobonyl isobutyrate, long chain alcohols such as α-terpineol and butyl carbitol, long Examples thereof include esters of chain alcohol and carboxylic acid. In addition to the above organic solvents, organic solvents that are partially miscible with water, such as ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, can also be used.
（有機バインダー）
有機バインダーとしては、例えばメチルセルロース、エチルセルロース、ニトロセルロース、酢酸セルロース、プロピオン酸セルロース等のセルロース系樹脂、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル等のアクリル酸エステル類、アルキッド樹脂、及びポリビニルアルコール等が使用できる。また、有機バインダーは、エタノール、ブタノール等の有機溶媒を添加した状態で使用してもよく、あるいは、上述の水と混和しない有機溶媒に溶解して使用してもよい。なお、有機ビヒクルの配合量は、目的とする導電性ペーストのレベリング性や垂れ性の粘度特性に応じて適宜調節することができる。
(Organic binder)
Examples of the organic binder include cellulosic resins such as methyl cellulose, ethyl cellulose, nitrocellulose, cellulose acetate, and cellulose propionate, and acrylate esters such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , Alkid resin, polyvinyl alcohol and the like can be used. Further, the organic binder may be used in a state where an organic solvent such as ethanol or butanol is added, or may be used by dissolving it in the above-mentioned organic solvent immiscible with water. The blending amount of the organic vehicle can be appropriately adjusted according to the leveling property and the dripping viscosity property of the target conductive paste.
（非水系高分子分散剤）
非水系高分子分散剤は、主骨格に低極性溶媒との親和性が高く、低極性基を有する高分子化合物であり、更に官能基としてアミノ基を有するものである。このような高分子化合物は、例えばポリアミド系、ポリアリルアミン系、ポリエステル系、ポリウレタン系、ポリオキシアルキレン系などの分子骨格を有するものが挙げられ、この中でも特に好ましくはポリウレタン系、ポリオキシエチレン系の分子骨格を有するものがよい。また、その分子構造は、線状の直鎖型若しくは櫛型、又は線状の主鎖に線状の側鎖が結合した三叉分岐点を有する櫛型、あるいはブロック共重合体、又はグラフト共重合体でもよいが、その分子内に２級又は３級のアミノ基を１以上有するものである。
(Non-aqueous polymer dispersant)
The non-aqueous polymer dispersant is a polymer compound having a high affinity for a low polar solvent in the main skeleton and having a low polar group, and further has an amino group as a functional group. Examples of such polymer compounds include those having a molecular skeleton such as polyamide-based, polyallylamine-based, polyester-based, polyurethane-based, and polyoxyalkylene-based, and among them, polyurethane-based and polyoxyethylene-based are particularly preferable. Those having a molecular skeleton are preferable. The molecular structure thereof is a linear linear type or comb type, or a comb type having a three-pronged branch point in which a linear side chain is bonded to a linear main chain, a block copolymer, or a graft copolymer. It may be coalesced, but it has one or more secondary or tertiary amino groups in the molecule.
本実施の形態で用いる非水系高分子分散剤の２級又は３級のアミノ基は、ニッケル粒子の表面に固定化された脂肪族１級モノアミンとの置換反応が可能であるため、ニッケル粒子の表面において脂肪族１級モノアミンの少なくとも一部分と容易に置換し、ニッケル粒子を被覆できると考えられる。この非水系高分子分散剤は、ニッケル粒子に対し、強い凝集抑制作用を有することから、少量でも優れた分散効果が期待できる。一方、ニッケル粒子の表面に脂肪族１級モノアミンが存在しない場合には、非水系高分子分散剤を添加しても脂肪族１級モノアミンとの置換による被覆が生じにくく、強い凝集抑制作用や優れた分散効果が得られない。なお、非水系高分子分散剤に含まれる３級アミノ基は、その一部にアルキル基が結合して４級アンモニウムイオンとして存在していてもよい。また、これらのアミノ基は、線状の主鎖に櫛状に有するか、又は線状の主鎖の末端に有するものが好ましく、これらに存在する個々のアミノ基がニッケル粒子の表面に点在的に固定化されるものと考えられる。 Since the secondary or tertiary amino group of the non-aqueous polymer dispersant used in the present embodiment can undergo a substitution reaction with the aliphatic primary monoamine immobilized on the surface of the nickel particles, the nickel particles can be replaced with the nickel particles. It is believed that the surface can be easily replaced with at least a portion of the aliphatic primary monoamine to coat the nickel particles. Since this non-aqueous polymer dispersant has a strong aggregation inhibitory effect on nickel particles, an excellent dispersion effect can be expected even in a small amount. On the other hand, when the aliphatic primary monoamine is not present on the surface of the nickel particles, even if a non-aqueous polymer dispersant is added, coating by substitution with the aliphatic primary monoamine is unlikely to occur, and a strong aggregation inhibitory effect and excellent The dispersion effect cannot be obtained. The tertiary amino group contained in the non-aqueous polymer dispersant may be present as a quaternary ammonium ion with an alkyl group bonded to a part thereof. Further, these amino groups preferably have a comb shape in the linear main chain or at the end of the linear main chain, and individual amino groups present in these are scattered on the surface of the nickel particles. It is considered to be fixed.
非水系高分子分散剤のアミン価（又は塩基価）は、分散性を向上させるという観点から、好ましくは１０〜１００ｍｇＫＯＨ／ｇの範囲内がよい。アミン価（又は塩基価）は、非水系高分子分散剤の固形分（又は溶媒を除いた有効成分）１ｇを中和するのに必要なＨＣｌ量に対して当量となるＫＯＨのｍｇ数を意味し、ＪＩＳ Ｋ７２３７の方法により測定される。また、非水系高分子分散剤の酸価は、分散性を向上させるという観点から、好ましくは１５ｍｇＫＯＨ／ｇ以下、より好ましくは１０ｍｇＫＯＨ／ｇ以下とすることがよい。酸価は、固形分（又は溶媒を除いた有効成分）１ｇを中和するのに必要なＫＯＨのｍｇ数を意味し、ＪＩＳ Ｋ００７０の方法により測定される。 The amine value (or base value) of the non-aqueous polymer dispersant is preferably in the range of 10 to 100 mgKOH / g from the viewpoint of improving dispersibility. The amine value (or base value) means the number of mg of KOH equivalent to the amount of HCl required to neutralize 1 g of the solid content (or the active ingredient excluding the solvent) of the non-aqueous polymer dispersant. Then, it is measured by the method of JIS K7237. The acid value of the non-aqueous polymer dispersant is preferably 15 mgKOH / g or less, more preferably 10 mgKOH / g or less, from the viewpoint of improving dispersibility. The acid value means the number of mg of KOH required to neutralize 1 g of the solid content (or the active ingredient excluding the solvent), and is measured by the method of JIS K0070.
非水系高分子分散剤の重量平均分子量は、好ましくは１,０００〜２００,０００の範囲内、より好ましくは５,０００〜１００,０００の範囲内がよい。重量平均分子量が、上記下限未満であると、低極性溶媒に対し分散安定性が十分ではない場合があり、上記上限を超えると、粘度が高くなりすぎて取り扱いが困難になる場合がある。 The weight average molecular weight of the non-aqueous polymer dispersant is preferably in the range of 1,000 to 200,000, more preferably in the range of 5,000 to 100,000. If the weight average molecular weight is less than the above lower limit, the dispersion stability may not be sufficient with respect to the low polar solvent, and if it exceeds the above upper limit, the viscosity may become too high and handling may be difficult.
非水系高分子分散剤は、単独又は２種以上を組み合わせて使用することもできる。また、発明の効果を損なわない範囲で、他の化合物からなる分散剤と組み合わせて使用することもできる。好適に使用することができる市販の非水系高分子分散剤としては、例えば、日本ルーブリゾール社製のＳｏｌｓｐｅｒｓｅ１１２００（商品名）、同Ｓｏｌｓｐｅｒｓｅ１３９４０（商品名）、同Ｓｏｌｓｐｅｒｓｅ１３２４０（商品名）、ビッグケミー・ジャパン社製のＤＩＳＰＥＲＢＹＫ−１６１（商品名）、同ＤＩＳＰＥＲＢＹＫ−１６３（商品名）、ＤＩＳＰＥＲＢＹＫ−２１６４（商品名）、ＤＩＳＰＥＲＢＹＫ−２１５５（商品名）等が挙げられる。 The non-aqueous polymer dispersant may be used alone or in combination of two or more. Further, it can be used in combination with a dispersant composed of other compounds as long as the effects of the invention are not impaired. Examples of commercially available non-aqueous polymer dispersants that can be preferably used include Solspace 11200 (trade name), Solspace 13940 (trade name), Solspace 13240 (trade name) manufactured by Japan Lubrizol Co., Ltd., and Big Chemie Japan Co., Ltd. DISPERBYK-161 (trade name), DISPERBYK-163 (trade name), DISPERBYK-2164 (trade name), DISPERBYK-2155 (trade name), etc.
導電性ペーストにおける非水系高分子分散剤の添加量は、ニッケル粒子１００質量部に対して０．０１〜２０質量部の範囲内、好ましくは０．１〜１０質量部の範囲内がよい。添加量が上記下限未満では分散性が低下する傾向があり、上記上限を超えると、凝集が生じ易くなる傾向がある。 The amount of the non-aqueous polymer dispersant added to the conductive paste is preferably in the range of 0.01 to 20 parts by mass, preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the nickel particles. If the addition amount is less than the above lower limit, the dispersibility tends to decrease, and if it exceeds the above upper limit, aggregation tends to occur easily.
本実施の形態の導電性ペーストは、上記構成ａ〜ｄを備えたニッケル粒子を含有することによって、導電性ペースト中のニッケル粒子を高い分散状態に維持できる。その結果、導電性ペーストを塗布して電極膜を形成した場合の表面粗さを小さくすることができ、電気信頼性も向上させることができる。例えば、後記実施例に示す方法で測定される導電性ペーストの表面粗さの評価において、算術平均粗さＲａを０．００５μｍ以下、好ましくは、０．００２μｍ以下に抑制できる。 By containing the nickel particles having the above configurations a to d, the conductive paste of the present embodiment can maintain the nickel particles in the conductive paste in a highly dispersed state. As a result, the surface roughness when the conductive paste is applied to form the electrode film can be reduced, and the electrical reliability can be improved. For example, in the evaluation of the surface roughness of the conductive paste measured by the method shown in Examples described later, the arithmetic average roughness Ra can be suppressed to 0.005 μm or less, preferably 0.002 μm or less.
＜導電性ペーストの調製＞
ニッケル粒子及び有機ビヒクルを含有する導電性ペーストを調製する方法は、特に制限はない。例えば、公知の導電性ペーストの製造と同様に、各成分を混合した後、撹拌、混練などの処理を行うことにより導電性ペーストを調製できる。ここで、各成分を混合する順序の好ましい例を挙げれば、以下のとおりとなる。まず、上記構成ａ〜ｄを備えたニッケル粒子と有機溶媒のスラリーに、非水系高分子分散剤を適用する。スラリーへの非水系高分子分散剤の適用方法は、特に制限はなく、例えば、ｉ）スラリー中に所定量の非水系高分子分散剤を添加する方法、ii）高圧ホモジナイザー、超音波ホモジナイザー、ビーズミル分散機などの分散機を用い、スラリーの状態で、脂肪族１級モノアミンで被覆されたニッケル粒子を機械的に解砕し、その解砕の前又は後に、所定量の非水系高分子分散剤を添加し分散させる方法など、様々な方法が挙げられる。このようにスラリーの状態で、非水系高分子分散剤を適用することにより、非水系高分子分散剤の２級又は３級のアミノ基を、ニッケル粒子の表面に固定化された脂肪族１級モノアミンの少なくとも一部分と置換し、非水系高分子分散剤によってニッケル粒子を被覆できる。次に、スラリーに所定量の有機バインダー（有機溶媒に溶解させた状態でもよい）を添加し、混合、混練等を行うことによって、導電性ペーストを製造することができる。
<Preparation of conductive paste>
The method for preparing the conductive paste containing the nickel particles and the organic vehicle is not particularly limited. For example, as in the production of a known conductive paste, the conductive paste can be prepared by mixing each component and then performing treatments such as stirring and kneading. Here, a preferable example of the order in which each component is mixed is as follows. First, a non-aqueous polymer dispersant is applied to a slurry of nickel particles and an organic solvent having the above configurations a to d. The method of applying the non-aqueous polymer dispersant to the slurry is not particularly limited. For example, i) a method of adding a predetermined amount of the non-aqueous polymer dispersant to the slurry, ii) a high-pressure homogenizer, an ultrasonic homogenizer, and a bead mill. Using a disperser such as a disperser, nickel particles coated with an aliphatic primary monoamine are mechanically crushed in a slurry state, and a predetermined amount of a non-aqueous polymer dispersant is used before or after the crushing. There are various methods such as a method of adding and dispersing the above. By applying the non-aqueous polymer dispersant in the state of the slurry in this way, the secondary or tertiary amino group of the non-aqueous polymer dispersant is immobilized on the surface of the nickel particles, which is an aliphatic primary. The nickel particles can be coated with a non-aqueous polymer dispersant by substituting at least a part of the monoamine. Next, a conductive paste can be produced by adding a predetermined amount of an organic binder (which may be dissolved in an organic solvent) to the slurry and mixing, kneading, or the like.
上記のようにして導電性ペーストを得ることができるが、本発明の効果を損なわない範囲で、可塑剤、潤滑剤、分散剤、帯電防止剤、ゲル化防止剤等を添加してもよい。 Although the conductive paste can be obtained as described above, a plasticizer, a lubricant, a dispersant, an antistatic agent, an antigelling agent and the like may be added as long as the effects of the present invention are not impaired.
［ニッケル粒子の製造方法］
本実施の形態に係るニッケル粒子の製造方法は、例えば、下記の工程I〜IVを含むことができる。
[Manufacturing method of nickel particles]
The method for producing nickel particles according to the present embodiment can include, for example, the following steps I to IV.
＜工程Ｉ＞
本工程は、走査型電子顕微鏡観察による平均粒子径が１０ｎｍ以上３０ｎｍ以下の範囲内、ニッケル元素に対する銅元素の含有割合が３重量％以上３０重量％以下の範囲内である種粒子を準備する工程である。
<Step I>
This step is a step of preparing seed particles having an average particle diameter of 10 nm or more and 30 nm or less and a copper element content ratio of 3% by weight or more and 30% by weight or less of nickel element by scanning electron microscope observation. Is.
種粒子は、工程IVにおいて、ニッケル粒子の成長の核として機能するものである。種粒子は、例えば、ニッケル塩及び銅塩を含む原料から、有機アミンの存在下で加熱による湿式還元によって製造することが好ましい。この場合、銅とニッケルとの標準電極電位の相違から、まず、核となる銅粒子が形成され、次に、銅粒子の表面にニッケル被膜が形成されることによって、種粒子が得られる。 The seed particles serve as the core of nickel particle growth in step IV. The seed particles are preferably produced from, for example, a raw material containing a nickel salt and a copper salt by wet reduction by heating in the presence of an organic amine. In this case, seed particles are obtained by first forming core copper particles and then forming a nickel film on the surface of the copper particles from the difference in standard electrode potential between copper and nickel.
（銅塩）
銅塩としては、例えばカルボン酸銅を用いることが好ましい。また、カルボン酸銅としては、例えば、還元過程での解離温度（分解温度）が比較的低いギ酸銅、酢酸銅などを用いることが好ましい。また、カルボン酸銅は、無水物であってもよく、水和物であってもよい。銅塩を配合することによって、種粒子の形成を促進できるとともに、種粒子の粒子径の制御が容易になる。また、工程IVで得られるニッケル粒子の分散性を改善することができる。
(Copper salt)
As the copper salt, for example, copper carboxylate is preferably used. Further, as the copper carboxylate, for example, copper formate, copper acetate or the like having a relatively low dissociation temperature (decomposition temperature) in the reduction process is preferably used. Further, the copper carboxylate may be an anhydride or a hydrate. By blending the copper salt, the formation of seed particles can be promoted, and the particle size of the seed particles can be easily controlled. In addition, the dispersibility of the nickel particles obtained in step IV can be improved.
（ニッケル塩）
ニッケル塩としては、例えばカルボン酸ニッケルを用いることが好ましい。また、カルボン酸ニッケルとしては、例えば、還元過程での解離温度（分解温度）が比較的低いギ酸ニッケル、酢酸ニッケルなどを用いることが好ましい。カルボン酸ニッケルは、無水物であってもよく、また水和物であってもよい。なお、カルボン酸ニッケルに代えて、塩化ニッケル、硝酸ニッケル、硫酸ニッケル、炭酸ニッケル、水酸化ニッケル等の無機塩を用いることも考えられるが、無機塩の場合、解離(分解)が高温であるため、還元過程で高温での加熱が必要であり好ましくない。また、Ｎｉ（ａｃａｃ）２（β−ジケトナト錯体)、ステアリン酸イオン等の有機配位子により構成されるニッケル塩を用いることも考えられるが、これらのニッケル塩を用いると、原料コストが高くなり好ましくない。
(Nickel salt)
As the nickel salt, for example, nickel carboxylate is preferably used. Further, as the nickel carboxylate, for example, nickel formate or nickel acetate having a relatively low dissociation temperature (decomposition temperature) in the reduction process is preferably used. Nickel carboxylate may be anhydrous or hydrated. It is conceivable to use inorganic salts such as nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, and nickel hydroxide instead of nickel carboxylate, but in the case of inorganic salts, the dissociation (decomposition) is high. , Heating at high temperature is required in the reduction process, which is not preferable. It is also conceivable to use nickel salts composed of organic ligands such as Ni (acac) 2 (β-diketonato complex) and stearate ion, but if these nickel salts are used, the raw material cost becomes high. Not preferable.
なお、種粒子は、ニッケル及び銅以外の金属を含有していてもよい。その場合、種粒子の調製に際して、例えば、銀、金、白金及びパラジウムから選ばれる１種以上の金属の塩を使用してもよい。これらの金属の塩としては、例えば酢酸パラジウムなどのカルボン酸塩、硝酸銀などの硝酸塩、塩化金酸、塩化白金酸などの塩化物などを用いることが好ましい。金属塩は、無水物であってもよく、また水和物であってもよい。 The seed particles may contain a metal other than nickel and copper. In that case, in preparing the seed particles, for example, a salt of one or more metals selected from silver, gold, platinum and palladium may be used. As the salts of these metals, for example, carboxylic acid salts such as palladium acetate, nitrates such as silver nitrate, and chlorides such as chloroauric acid and platinum chloride acid are preferably used. The metal salt may be anhydrous or hydrated.
種粒子における銅元素の含有量は、例えば３重量％以上３０重量％以下の範囲内とすることが好ましい。種粒子における銅元素の含有量が３重量％未満であると、銅の核材としての効果が低下し、微細な球状で粒度分布が均一な種粒子を作りにくくなり、また、成長したニッケル粒子の磁性を抑制する効果が十分に得られず、凝集が生じやすくなる傾向がある。一方、種粒子における銅元素の含有量が３０重量％を超えると、銅の核材としての効果が飽和し、微細な種粒子を作る為の効果は得にくく、種粒子の段階で表面が酸化しやすくなる。また、金属として、銅以外のものを用いる場合、例えば、銀などのニッケル以外の異種金属によるマイグレーションによるショートや静電容量の低下などの製品不良を防止する観点から、銅以外の金属元素の含有量を０．０１重量％以上２重量％以下の範囲内とすることが好ましい。 The content of the copper element in the seed particles is preferably in the range of, for example, 3% by weight or more and 30% by weight or less. If the content of the copper element in the seed particles is less than 3% by weight, the effect of copper as a core material is reduced, it becomes difficult to produce seed particles having fine spheres and a uniform particle size distribution, and the grown nickel particles. The effect of suppressing the magnetism of copper is not sufficiently obtained, and agglomeration tends to occur easily. On the other hand, when the content of the copper element in the seed particles exceeds 30% by weight, the effect of copper as a core material is saturated, it is difficult to obtain the effect of producing fine seed particles, and the surface is oxidized at the stage of the seed particles. It will be easier to do. When a metal other than copper is used, for example, from the viewpoint of preventing product defects such as short circuit due to migration by a dissimilar metal other than nickel such as silver and a decrease in capacitance, the inclusion of a metal element other than copper. The amount is preferably in the range of 0.01% by weight or more and 2% by weight or less.
（有機アミン）
有機アミンは、ニッケルイオンとの錯体を形成できるものであれば、特に限定されず、常温で固体又は液体のものが使用できる。ここで、常温とは、２０℃±１５℃をいう。常温で液体の有機アミンは、ニッケル錯体を形成する際の有機溶媒としても機能する。なお、常温で固体の有機アミンであっても、加熱によって液体であるか、又は有機溶媒を用いて溶解するものであれば、特に問題はない。
(Organic amine)
The organic amine is not particularly limited as long as it can form a complex with nickel ions, and a solid or liquid amine can be used at room temperature. Here, the normal temperature means 20 ° C. ± 15 ° C. The organic amine, which is liquid at room temperature, also functions as an organic solvent when forming a nickel complex. Even if it is an organic amine that is solid at room temperature, there is no particular problem as long as it is a liquid by heating or is dissolved by using an organic solvent.
有機アミンとしては、脂肪族１級モノアミンを用いることが好ましい。一方、２級アミンは立体障害が大きいため、ニッケル錯体の良好な形成を阻害するおそれがあり、３級アミンはニッケルイオンの還元能を有しないため、いずれも使用できない。また、ジアミンは、金属イオンの中でも特にニッケルイオンと形成した錯体の安定性が高く、その還元温度は高くなるため反応性が非常に低く、生成するニッケル粒子に歪が生じやすくなるため好ましくない。 As the organic amine, it is preferable to use an aliphatic primary monoamine. On the other hand, since the secondary amine has a large steric hindrance, it may hinder the good formation of the nickel complex, and since the tertiary amine does not have the reducing ability of nickel ions, neither of them can be used. Further, diamine is not preferable because the stability of the complex formed with the nickel ion is particularly high among the metal ions, the reduction temperature is high, the reactivity is very low, and the generated nickel particles are easily distorted.
脂肪族１級モノアミンは、例えばその炭素鎖の長さを調整することによって生成する種粒子の粒径を制御することができる。種粒子の粒径を制御する観点から、脂肪族１級モノアミンは、その炭素数が６〜２０程度のものから選択して用いることが好適である。炭素数が多いほど得られる種粒子の粒径が小さくなる。このようなアミンとして、例えばオクチルアミン、トリオクチルアミン、ジオクチルアミン、ヘキサデシルアミン、ドデシルアミン、テトラデシルアミン、ステアリルアミン、オレイルアミン、ミリスチルアミン、ラウリルアミン等を挙げることができる。 Aliphatic primary monoamines can control the particle size of seed particles produced, for example, by adjusting the length of their carbon chains. From the viewpoint of controlling the particle size of the seed particles, it is preferable to select and use the aliphatic primary monoamine from those having about 6 to 20 carbon atoms. The larger the number of carbon atoms, the smaller the particle size of the obtained seed particles. Examples of such amines include octylamine, trioctylamine, dioctylamine, hexadecylamine, dodecylamine, tetradecylamine, stearylamine, oleylamine, myristylamine, laurylamine and the like.
脂肪族１級モノアミンは、種粒子の生成時に表面修飾剤として機能するため、脂肪族１級モノアミンの除去後においても二次凝集を抑制できる。また、脂肪族１級モノアミンは、還元反応後の生成した種粒子の固体成分と溶剤又は未反応の脂肪族１級モノアミン等を分離する洗浄工程における処理操作の容易性の観点からも好ましい。更に、脂肪族１級モノアミンは、ニッケル錯体を還元して種粒子を得るときの反応制御の容易性の観点からは還元温度より沸点が高いものが好ましい。すなわち、脂肪族１級モノアミンは、沸点が１８０℃以上のものが好ましく、２００℃以上のものがより好ましい。また、脂肪族１級モノアミンは、炭素数が９以上であることが好ましい。ここで、例えば炭素数が９である脂肪族１級モノアミンのＣ９Ｈ２１Ｎ(ノニルアミン)の沸点は２０１℃である。 Since the aliphatic primary monoamine functions as a surface modifier during the formation of seed particles, secondary aggregation can be suppressed even after the removal of the aliphatic primary monoamine. The aliphatic primary monoamine is also preferable from the viewpoint of ease of treatment operation in the washing step of separating the solid component of the seed particles produced after the reduction reaction from the solvent or the unreacted aliphatic primary monoamine. Further, the aliphatic primary monoamine preferably has a boiling point higher than the reduction temperature from the viewpoint of ease of reaction control when reducing the nickel complex to obtain seed particles. That is, the aliphatic primary monoamine preferably has a boiling point of 180 ° C. or higher, and more preferably 200 ° C. or higher. Further, the aliphatic primary monoamine preferably has 9 or more carbon atoms. Here, for example, the boiling point of C 9 H 21 N (nonylamine) of an aliphatic primary monoamine having 9 carbon atoms is 201 ° C.
脂肪族１級モノアミンは、還元反応後の生成した種粒子の固体成分と溶剤または未反応の脂肪族１級モノアミン等を分離する洗浄工程における処理操作の容易性の観点から、室温で液体のものが好ましい。更に、脂肪族１級モノアミンは、銅錯体を還元して種粒子を得るときの反応制御の容易性の観点から、還元温度より沸点が高いものが好ましい。脂肪族１級モノアミンの量は、金属イオン（ニッケルイオン及び銅イオンの合計）１ｍｏｌに対して５ｍｏｌ以上用いることが好ましく、８ｍｏｌ以上用いることがより好ましい。脂肪族１級モノアミンの量が５ｍｏｌ未満では、得られるニッケル粒子の粒子径の制御が困難となり、粒子径がばらつきやすくなる。また、脂肪族１級モノアミンの量の上限は特にはないが、例えば生産性の観点からは、金属イオン１ｍｏｌに対して２０ｍｏｌ以下とすることが好ましく、１５ｍｏｌ以下とすることがより好ましい。つまり、脂肪族１級モノアミンの量は、金属イオン１ｍｏｌに対して５〜２０ｍｏｌの範囲内が好ましく、８〜１５ｍｏｌの範囲内がより好ましい。 Aliphatic primary monoamines are liquid at room temperature from the viewpoint of ease of treatment in the washing step of separating the solid component of the seed particles produced after the reduction reaction from the solvent or unreacted aliphatic primary monoamines. Is preferable. Further, the aliphatic primary monoamine preferably has a boiling point higher than the reduction temperature from the viewpoint of easiness of reaction control when reducing the copper complex to obtain seed particles. The amount of the aliphatic primary monoamine is preferably 5 mol or more, more preferably 8 mol or more, with respect to 1 mol of the metal ion (total of nickel ion and copper ion). If the amount of the aliphatic primary monoamine is less than 5 mol, it becomes difficult to control the particle size of the obtained nickel particles, and the particle size tends to vary. The upper limit of the amount of the aliphatic primary monoamine is not particularly limited, but for example, from the viewpoint of productivity, it is preferably 20 mol or less, and more preferably 15 mol or less with respect to 1 mol of the metal ion. That is, the amount of the aliphatic primary monoamine is preferably in the range of 5 to 20 mol, more preferably in the range of 8 to 15 mol with respect to 1 mol of the metal ion.
（有機溶媒）
脂肪族１級モノアミンは、有機溶媒として反応を進行させることができるが、均一溶液での反応をより効率的に進行させるために、工程Ｉの種粒子の調製において、脂肪族１級モノアミンとは別の有機溶媒を新たに添加してもよい。使用できる有機溶媒としては、脂肪族１級モノアミンと、ニッケルイオン、銅イオンなどの金属イオンとの錯形成を阻害しないものであれば、特に限定するものではなく、例えば炭素数４〜３０のエーテル系有機溶媒、炭素数７〜３０の飽和又は不飽和の炭化水素系有機溶媒、炭素数８〜１８のアルコール系有機溶媒等を使用することができる。また、マイクロ波照射による加熱条件下でも使用を可能とする観点から、使用する有機溶媒は、沸点が１７０℃以上のものを選択することが好ましく、より好ましくは２００〜３００℃の範囲内にあるものを選択することがよい。このような有機溶媒の具体例としては、例えばテトラエチレングリコール、ｎ−オクチルエーテル、炭素数が２０〜４０の範囲内にあるポリアルファオレフィン等が挙げられる。
(Organic solvent)
The aliphatic primary monoamine can proceed as an organic solvent, but in order to proceed the reaction in a uniform solution more efficiently, in the preparation of the seed particles in step I, the aliphatic primary monoamine is used. Another organic solvent may be newly added. The organic solvent that can be used is not particularly limited as long as it does not inhibit the complex formation between the aliphatic primary monoamine and metal ions such as nickel ion and copper ion, and is not particularly limited, for example, an ether having 4 to 30 carbon atoms. A system-based organic solvent, a saturated or unsaturated hydrocarbon-based organic solvent having 7 to 30 carbon atoms, an alcohol-based organic solvent having 8 to 18 carbon atoms, or the like can be used. Further, from the viewpoint of enabling the use even under heating conditions by microwave irradiation, it is preferable to select an organic solvent having a boiling point of 170 ° C. or higher, more preferably in the range of 200 to 300 ° C. It is better to choose one. Specific examples of such an organic solvent include tetraethylene glycol, n-octyl ether, polyalphaolefin having a carbon number in the range of 20 to 40, and the like.
（加熱還元）
工程Ｉにおいて、種粒子を形成するための加熱還元方法は、特に制限されず、例えばオイルバスなどの熱媒体による加熱であっても、マイクロ波照射による加熱であってもよいが、均一、かつ急速な加熱が可能なマイクロ波照射による加熱が好ましい。マイクロ波の使用波長は、特に限定するものではなく、例えば２．４５ＧＨｚである。
(Heat reduction)
In step I, the heating reduction method for forming the seed particles is not particularly limited, and may be heating with a heat medium such as an oil bath or heating with microwave irradiation, but it is uniform and Heating by microwave irradiation, which enables rapid heating, is preferable. The wavelength used for microwaves is not particularly limited, and is, for example, 2.45 GHz.
種粒子を形成するための加熱温度は、種粒子の形状のばらつきを抑制するという観点から、好ましくは１７０℃以上、より好ましくは１８０℃以上とすることがよい。加熱温度の上限は特にないが、処理を能率的に行う観点から、例えば２７０℃以下とすることが好適である。 The heating temperature for forming the seed particles is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, from the viewpoint of suppressing variations in the shape of the seed particles. There is no particular upper limit to the heating temperature, but from the viewpoint of efficient treatment, it is preferably 270 ° C. or lower, for example.
以上のようにして、種粒子を含有するスラリーを得ることが出来る。なお、工程Ｉでは、種粒子を含有するスラリーを、例えば、静置分離し、上澄み液を取り除いた後、適当な溶媒を用いて洗浄し、乾燥することで種粒子を分取してもよい。 As described above, a slurry containing seed particles can be obtained. In step I, the seed particles may be separated by, for example, statically separating the slurry containing the seed particles, removing the supernatant, washing the slurry with an appropriate solvent, and drying the slurry. ..
（種粒子）
工程Ｉで得られる種粒子の走査型電子顕微鏡観察による平均粒子径は、１０ｎｍ以上３０ｎｍ以下の範囲内である。種粒子の平均粒子径が１０ｎｍ未満では、ハンドリング性が低下するとともに、凝集しやすくなって、核材として用いた場合に、粒子径分布がシャープなニッケル粒子を安定的に製造することが難しくなる。一方、種粒子の平均粒子径が３０ｎｍを超えると、種粒子の段階での粒子径のばらつきが大きくなって、やはり、核材として用いた場合に、粒子径分布がシャープなニッケル粒子を安定的に製造することが困難になる。また、種粒子の平均粒子径は、ＳＥＭ（走査型電子顕微鏡）により試料の写真を撮影して、その中から無作為に２００個を抽出してそれぞれの粒子について面積を求め、真球に換算したときの粒子径から、個数基準にて求めることができる。
(Seed particle)
The average particle size of the seed particles obtained in step I by scanning electron microscope observation is in the range of 10 nm or more and 30 nm or less. If the average particle size of the seed particles is less than 10 nm, the handleability is lowered and the seed particles are easily aggregated, and when used as a core material, it becomes difficult to stably produce nickel particles having a sharp particle size distribution. .. On the other hand, when the average particle size of the seed particles exceeds 30 nm, the variation in the particle size at the stage of the seed particles becomes large, and when used as a core material, nickel particles having a sharp particle size distribution are stable. It becomes difficult to manufacture. The average particle size of the seed particles is converted to a true sphere by taking a picture of the sample with a SEM (scanning electron microscope), randomly extracting 200 particles from the sample, calculating the area of each particle, and converting it into a true sphere. It can be obtained on the basis of the number of particles from the particle size at that time.
また、工程Ｉで得られる種粒子は、粒子径の変動係数（ＣＶ値）が、０．２以下であることが好ましく、０．１５以下であることがより好ましい。ＣＶ値が０．２を超えると、後の工程IVで得られるニッケル粒子の粒子径のばらつきが大きくなることがある。 Further, the seed particles obtained in step I preferably have a coefficient of variation (CV value) of 0.2 or less, and more preferably 0.15 or less. If the CV value exceeds 0.2, the variation in particle size of the nickel particles obtained in the subsequent step IV may become large.
＜工程II＞
本工程は、ニッケル塩を有機アミンに溶解させたニッケル錯体溶液を準備する工程である。
<Process II>
This step is a step of preparing a nickel complex solution in which a nickel salt is dissolved in an organic amine.
（ニッケル塩）
工程IIにおいて、ニッケル塩の種類は特に限定されず、例えば水酸化ニッケル、塩化ニッケル、硝酸ニッケル、硫酸ニッケル、炭酸ニッケル、カルボン酸ニッケル、Ｎｉ（ａｃａｃ）２（β−ジケトナト錯体）、ステアリン酸ニッケル等が挙げられるが、この中でも、塩化ニッケル又はカルボン酸ニッケルが好ましく、還元過程での解離温度（分解温度）が比較的低いカルボン酸ニッケルを用いることが有利である。カルボン酸ニッケルは単独で用いてもよいし、他のニッケル塩と併用することもできる。工程IIにおけるニッケル塩としては、工程Ｉと同様のものを用いることができる。
(Nickel salt)
In step II, the type of nickel salt is not particularly limited, and for example, nickel hydroxide, nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, nickel carboxylate, Ni (acac) 2 (β-diketonato complex), nickel stearate. Among these, nickel chloride or nickel carboxylate is preferable, and it is advantageous to use nickel carboxylate having a relatively low dissociation temperature (decomposition temperature) in the reduction process. Nickel carboxylate may be used alone or in combination with other nickel salts. As the nickel salt in step II, the same nickel salt as in step I can be used.
（有機アミン）
工程IIにおける有機アミンとしては、工程Ｉと同様のものを用いることができる。
(Organic amine)
As the organic amine in step II, the same organic amine as in step I can be used.
（ニッケル錯体溶液）
ニッケル錯体溶液中のニッケル錯体濃度は、例えば２〜１１重量％の範囲内とすることが好ましく、４〜８重量％の範囲内とすることがより好ましい。本実施の形態の製造方法では、種粒子を形成する工程Ｉと、種粒子からニッケル粒子を成長させる工程IVを区別する多段階の反応によって、一段階の合成法に比べ、均一な粒子径を有するニッケル粒子を製造できる。一段階の合成法では、ニッケル錯体濃度が１０重量％を超えると、反応性が低下するとともに、粒子径の制御が難しくなる。
(Nickel complex solution)
The nickel complex concentration in the nickel complex solution is preferably in the range of, for example, 2 to 11% by weight, and more preferably in the range of 4 to 8% by weight. In the production method of the present embodiment, a uniform particle size is obtained as compared with the one-step synthesis method by a multi-step reaction that distinguishes between step I for forming seed particles and step IV for growing nickel particles from seed particles. Nickel particles can be produced. In the one-step synthesis method, when the nickel complex concentration exceeds 10% by weight, the reactivity is lowered and the particle size is difficult to control.
２価のニッケルイオンは配位子置換活性種として知られており、形成する錯体の配位子は温度、濃度によって容易に配位子交換により錯形成が変化する可能性がある。例えばカルボン酸ニッケルおよび脂肪族１級モノアミンの混合物を加熱して反応液を得る工程において、用いるアミンの炭素鎖長等の立体障害を考慮すると、例えば、カルボン酸イオンが二座配位または単座配位のいずれかで配位する可能性があり、さらにアミンの濃度が大過剰の場合は外圏にカルボン酸イオンが存在する構造をとる可能性がある。目的とする反応温度（還元温度）において均一溶液とするには、配位子のうち少なくとも一箇所は脂肪族１級モノアミンが配位している必要がある。その状態をとるには、脂肪族１級モノアミンが過剰に反応溶液内に存在している必要があり、少なくともニッケルイオン１ｍｏｌに対し２ｍｏｌ以上存在していることが好ましく、２．２ｍｏｌ以上存在していることがより好ましい。また、脂肪族１級モノアミンの量の上限は特にはないが、例えば生産性の観点からは、ニッケルイオン１ｍｏｌに対して２０ｍｏｌ以下とすることが好ましく、４ｍｏｌ以下とすることがより好ましい。つまり、脂肪族１級モノアミンの量は、ニッケルイオン１ｍｏｌに対して２〜２０ｍｏｌの範囲内が好ましく、２〜４ｍｏｌの範囲内がより好ましく、２．２〜４ｍｏｌの範囲内が最も好ましい。 The divalent nickel ion is known as a ligand-substituted active species, and the ligand of the complex to be formed may easily change the complex formation by ligand exchange depending on the temperature and concentration. For example, in the step of heating a mixture of nickel carboxylate and an aliphatic primary monoamine to obtain a reaction solution, considering steric hindrance such as the carbon chain length of the amine used, for example, the carboxylate ion is coordinated or monodentate. It may be coordinated at any of the positions, and if the amine concentration is too large, it may have a structure in which carboxylic acid ions are present in the outer zone. In order to obtain a uniform solution at the target reaction temperature (reduction temperature), at least one of the ligands needs to be coordinated with an aliphatic primary monoamine. In order to take that state, the aliphatic primary monoamine needs to be excessively present in the reaction solution, preferably at least 2 mol or more with respect to 1 mol of nickel ions, and 2.2 mol or more is present. Is more preferable. The upper limit of the amount of the aliphatic primary monoamine is not particularly limited, but for example, from the viewpoint of productivity, it is preferably 20 mol or less, and more preferably 4 mol or less with respect to 1 mol of nickel ions. That is, the amount of the aliphatic primary monoamine is preferably in the range of 2 to 20 mol, more preferably in the range of 2 to 4 mol, and most preferably in the range of 2.2 to 4 mol with respect to 1 mol of nickel ions.
錯形成反応は室温においても進行させることができるが、反応を確実かつより効率的に行うために、１００℃以上の温度で加熱を行うことが好ましい。この加熱は、カルボン酸ニッケルとして、例えば酢酸ニッケル４水和物のようなカルボン酸ニッケルの水和物を用いた場合に特に有利である。加熱温度は、好ましくは１００℃を超える温度とし、より好ましくは１０５℃以上の温度とすることで、カルボン酸ニッケルに配位した配位水と脂肪族１級モノアミンとの配位子置換反応が効率よく行われ、この錯体配位子としての水分子を解離させることができ、更にその水を系外に出すことができるので効率よく錯体を形成させることができる。例えば、酢酸ニッケル４水和物は、室温では２個の配位水と２座配位子である２個の酢酸イオン、外圏に２つの水分子が存在した錯体構造をとっているため、この２つの配位水と脂肪族１級モノアミンの配位子置換により効率よく錯形成させるには、１００℃より高い温度で加熱することでこの錯体配位子としての水分子を解離させることが好ましい。また、加熱温度は、後に続く還元の過程と確実に分離し、錯形成反応を完結させるという観点から、１７５℃以下が好ましい。工程IIでの加熱温度が高すぎると、ニッケル錯体の生成とニッケル(０価)への還元反応が同時に進行し、新たにニッケルの核が発生してしまうことで、粒子径の分布が狭いニッケル粒子の生成が困難となるおそれがある。従って、工程IIにおける加熱温度は１０５℃〜１７５℃の範囲内が好ましく、より好ましくは、１２５〜１６０℃の範囲内である。 Although the complex formation reaction can proceed at room temperature, it is preferable to heat at a temperature of 100 ° C. or higher in order to carry out the reaction reliably and more efficiently. This heating is particularly advantageous when a nickel carboxylate hydrate, such as nickel acetate tetrahydrate, is used as the nickel carboxylate. The heating temperature is preferably a temperature exceeding 100 ° C., more preferably a temperature of 105 ° C. or higher, so that the ligand substitution reaction between the coordinated water coordinated to nickel carboxylate and the aliphatic primary monoamine can be carried out. This is efficiently performed, the water molecule as the complex ligand can be dissociated, and the water can be discharged to the outside of the system, so that a complex can be efficiently formed. For example, nickel acetate tetrahydrate has a complex structure in which two coordinated waters, two bidentate ligands, acetate ions, and two water molecules exist in the outer sphere at room temperature. In order to efficiently form a complex by the ligand substitution of these two coordinated waters and the aliphatic primary monoamine, it is necessary to dissociate the water molecule as the complex ligand by heating at a temperature higher than 100 ° C. preferable. Further, the heating temperature is preferably 175 ° C. or lower from the viewpoint of surely separating from the subsequent reduction process and completing the complex formation reaction. If the heating temperature in step II is too high, the formation of a nickel complex and the reduction reaction to nickel (zero valence) proceed at the same time, and new nickel nuclei are generated, resulting in a narrow particle size distribution of nickel. It may be difficult to generate particles. Therefore, the heating temperature in step II is preferably in the range of 105 ° C to 175 ° C, more preferably in the range of 125 to 160 ° C.
加熱時間は、加熱温度や、各原料の含有量に応じて適宜決定することができるが、錯形成反応を確実に完結させるという観点から、１５分以上とすることが好ましい。加熱時間の上限は特にないが、長時間加熱することは、エネルギー消費及び工程時間を節約する観点から無駄である。加熱の方法は、特に制限されず、例えばオイルバスなどの熱媒体による加熱であっても、マイクロ波照射による加熱であってもよいが、マイクロ波照射による加熱が好ましい。マイクロ波照射による加熱は、混合液内の均一加熱を可能とし、かつエネルギーをニッケルイオンに直接与えることができるため、急速加熱を行なうことができる。マイクロ波の使用波長は、特に限定するものではなく、例えば２．４５ＧＨｚである。 The heating time can be appropriately determined according to the heating temperature and the content of each raw material, but is preferably 15 minutes or more from the viewpoint of surely completing the complex formation reaction. There is no particular upper limit to the heating time, but heating for a long time is wasteful from the viewpoint of saving energy consumption and process time. The heating method is not particularly limited, and may be heating by a heat medium such as an oil bath or heating by microwave irradiation, but heating by microwave irradiation is preferable. Heating by microwave irradiation enables uniform heating in the mixed solution and can directly apply energy to nickel ions, so that rapid heating can be performed. The wavelength used for microwaves is not particularly limited, and is, for example, 2.45 GHz.
カルボン酸ニッケルと脂肪族１級モノアミンとの錯形成反応は、カルボン酸ニッケルと脂肪族１級モノアミンを混合して得られる溶液を加熱したときに、溶液の色の変化によって確認することができる。また、この錯形成反応は、例えば紫外・可視吸収スペクトル測定装置を用いて、３００ｎｍ〜７５０ｎｍの波長領域において観測される吸収スペクトルの吸収極大の波長を測定し、原料の極大吸収波長（例えば酢酸ニッケル四水和物ではその極大吸収波長は７１０ｎｍである。）に対する錯化反応液のシフトを観測することによって確認することができる。 The complex formation reaction between nickel carboxylate and the aliphatic primary monoamine can be confirmed by the change in color of the solution when the solution obtained by mixing nickel carboxylate and the aliphatic primary monoamine is heated. Further, in this complex formation reaction, for example, an ultraviolet / visible absorption spectrum measuring device is used to measure the maximum absorption wavelength of the absorption spectrum observed in the wavelength region of 300 nm to 750 nm, and the maximum absorption wavelength of the raw material (for example, nickel acetate) is measured. The maximum absorption wavelength of tetrahydrate is 710 nm), which can be confirmed by observing the shift of the complex reaction solution.
＜工程III＞
本工程は、工程Ｉで得た種粒子と、工程IIで得たニッケル錯体溶液とを混合して混合液を得る工程である。
<Process III>
This step is a step of mixing the seed particles obtained in step I with the nickel complex solution obtained in step II to obtain a mixed solution.
工程IIIでは、種粒子又は種粒子を含むスラリーを、ニッケル錯体溶液に添加してもよいし、種粒子を含むスラリーに、ニッケル錯体溶液を添加してもよい。工程IIIで混合されたニッケル錯体は、新たな核の形成には利用されず、次の工程IVで種粒子からニッケル粒子への成長に利用される。つまり、混合液中のニッケル錯体の濃度が、核形成の臨界濃度を超えない限り、ニッケル錯体は粒子成長にのみ利用される。従って、工程IVで目的とする粒子径のニッケル粒子を得るためのニッケル錯体の量は、種粒子の粒子径に基づき、計算上、算出することができる。 In step III, the seed particles or the slurry containing the seed particles may be added to the nickel complex solution, or the nickel complex solution may be added to the slurry containing the seed particles. The nickel complex mixed in step III is not used for the formation of new nuclei, but is used for the growth of seed particles to nickel particles in the next step IV. That is, the nickel complex is used only for particle growth unless the concentration of the nickel complex in the mixture exceeds the critical concentration of nucleation. Therefore, the amount of the nickel complex for obtaining the nickel particles having the target particle size in the step IV can be calculated and calculated based on the particle size of the seed particles.
＜工程IV＞
本工程は、工程IIIで得た混合液中のニッケルイオンを加熱還元し、前記種粒子を核としてニッケル粒子に成長させるとともに、該ニッケル粒子中の銅原子を拡散させてニッケル粒子を得る工程である。
<Process IV>
In this step, the nickel ions in the mixed solution obtained in step III are heated and reduced to grow into nickel particles with the seed particles as nuclei, and the copper atoms in the nickel particles are diffused to obtain nickel particles. is there.
（加熱還元）
工程IVにおける加熱方法は、特に制限されず、例えばマイクロ波照射による加熱でもよく、オイルバスなどの熱媒体による加熱であってもよい。マイクロ波照射によるニッケル錯体の加熱では、ニッケル錯体の均一加熱を可能とし、かつエネルギーをニッケル錯体に直接与えることができるため、急速加熱を行なうことができる。これにより、反応液全体を所望の温度に均一にすることができ、ニッケル錯体（又はニッケルイオン）の還元と成長を溶液全体において同時に生じさせ、結果として粒子径分布の狭い単分散な粒子を短時間で容易に製造することができる。マイクロ波の使用波長は、特に限定するものではなく、例えば２．４５ＧＨｚである。一方、オイルバスなどの熱媒体による加熱では、簡便な装置で行うことができるという利点があるが、マイクロ波照射による加熱と比較して、ニッケル錯体の均一加熱の効率や、エネルギーを与える効率は低い。そのため、マイクロ波照射による加熱よりも長時間の加熱を要する。加熱時間を短縮するために、加熱時の撹拌速度を上げても良い。また、加熱時間を長くすることで、加熱時の撹拌速度を下げることもできる。
(Heat reduction)
The heating method in the step IV is not particularly limited, and may be, for example, heating by microwave irradiation or heating by a heat medium such as an oil bath. In the heating of the nickel complex by microwave irradiation, uniform heating of the nickel complex is possible, and energy can be directly applied to the nickel complex, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and the reduction and growth of the nickel complex (or nickel ion) occur simultaneously in the entire solution, resulting in short monodisperse particles having a narrow particle size distribution. It can be easily manufactured in time. The wavelength used for microwaves is not particularly limited, and is, for example, 2.45 GHz. On the other hand, heating with a heat medium such as an oil bath has the advantage that it can be performed with a simple device, but the efficiency of uniform heating of the nickel complex and the efficiency of giving energy are higher than those of heating with microwave irradiation. Low. Therefore, heating for a longer time is required than heating by microwave irradiation. In order to shorten the heating time, the stirring speed during heating may be increased. Further, by lengthening the heating time, the stirring speed during heating can be lowered.
工程IVにおける加熱還元の温度は、得られるニッケル粒子の形状のばらつきを抑制するという観点から、好ましくは１７０℃以上、より好ましくは１８０℃以上とすることがよい。また、工程IVにおける加熱温度が低すぎると、ニッケル錯体からニッケル(０価)への還元反応速度が遅くなり、種粒子を覆う金属ニッケルの成長が遅くなる傾向がある。加熱温度の上限は特にないが、処理を能率的に行う観点からは例えば２７０℃以下とすることが好適である。また、２７０℃を超えると炭化反応が進行して炭化ニッケルが生成しやすくなるので、好ましくない。 The temperature of the heat reduction in the step IV is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, from the viewpoint of suppressing variation in the shape of the obtained nickel particles. Further, if the heating temperature in step IV is too low, the reduction reaction rate from the nickel complex to nickel (zero valence) becomes slow, and the growth of metallic nickel covering the seed particles tends to be slow. There is no particular upper limit to the heating temperature, but from the viewpoint of efficient treatment, it is preferably 270 ° C. or lower, for example. Further, if the temperature exceeds 270 ° C., the carbonization reaction proceeds and nickel carbide is easily produced, which is not preferable.
工程IVでは、加熱還元時の熱処理によって、ニッケル粒子中の銅元素を拡散させる。工程IVにおいて、ニッケルイオンの還元処理を加熱還元によって行うことによって、加熱還元と同時に銅元素を拡散させることができる。 In step IV, the copper element in the nickel particles is diffused by heat treatment during heat reduction. In step IV, by performing the reduction treatment of nickel ions by heat reduction, the copper element can be diffused at the same time as the heat reduction.
工程IVでは、得られたニッケル粒子のスラリーを、例えば、静置分離し、上澄み液を取り除いた後、適当な溶媒を用いて洗浄し、乾燥する処理を含むことができる。このようにして、上記の構成ａ〜ｄを備えたニッケル粒子が得られる。 Step IV can include, for example, static separation of the obtained nickel particle slurry, removal of the supernatant, washing with a suitable solvent, and drying. In this way, nickel particles having the above configurations a to d can be obtained.
上記の工程IIIの一部分と工程IVは、複数回繰り返し行うことも可能である。すなわち、工程IVを行った後で、さらにニッケル錯体溶液を添加し、再度工程IVを行ってもよい。この場合も、後から追加されたニッケル錯体は、新たな核の形成には利用されず、種粒子からニッケル粒子への成長に利用される。つまり、工程IIIの一部分と工程IVを繰り返し行う場合でも、混合液中へのニッケル錯体の追加速度が、粒子成長に消費される速度を超えない限り、ニッケル錯体の濃度が核形成の臨界濃度を超えることはないため、追加されたニッケル錯体は粒子成長にのみ利用される。従って、目的とする粒子径を得るためのニッケル錯体の量は、種粒子の粒子径に基づき、計算上、算出することができる。 A part of the above step III and step IV can be repeated a plurality of times. That is, after performing step IV, a nickel complex solution may be further added and step IV may be performed again. In this case as well, the nickel complex added later is not used for the formation of new nuclei, but is used for the growth of seed particles to nickel particles. That is, even when a part of step III and step IV are repeated, the concentration of the nickel complex is the critical concentration of nucleation as long as the rate of addition of the nickel complex to the mixed solution does not exceed the rate consumed for particle growth. Since it does not exceed, the added nickel complex is used only for particle growth. Therefore, the amount of the nickel complex for obtaining the target particle size can be calculated and calculated based on the particle size of the seed particles.
（ニッケル粒子）
工程IVで得られるニッケル粒子は、上記の構成ａ〜ｄを備えたものである。なお、工程Ｉで得られる種粒子の平均粒子径をｄ１、工程IVで得られるニッケル粒子の平均粒子径をｄ２とすると、ｄ１とｄ２の関係は、所定の粒子径のニッケル粒子を効率よく製造するという観点から、例えば２≦ｄ２／ｄ１であることが好ましい。それに対し、２＞ｄ２／ｄ１である場合は、銅元素の拡散が不十分となるおそれがある。
(Nickel particles)
The nickel particles obtained in step IV have the above configurations a to d. Assuming that the average particle size of the seed particles obtained in step I is d1 and the average particle size of the nickel particles obtained in step IV is d2, the relationship between d1 and d2 is that nickel particles having a predetermined particle size can be efficiently produced. From the viewpoint of this, for example, 2 ≦ d2 / d1 is preferable. On the other hand, when 2> d2 / d1, the diffusion of the copper element may be insufficient.
以上のように、工程I〜工程IVを実施することによって、平均粒子径が１５０ｎｍ以下であり、粒子径分布がシャープでＣＶ値が小さく、かつ分散性に優れたニッケル粒子を安定的に製造することができる。より具体的には、工程I〜工程IVを実施することによって、ニッケル元素を主成分とし、銅元素を含有するとともに、上記の構成ａ〜ｄを備えたニッケル粒子を製造することができる。構成ａ〜ｄを備えたニッケル粒子は、粒子内部に銅元素が拡散していることから、ニッケルの磁性を緩和し、磁性による凝集を抑制して分散性が向上するものと推察される。 As described above, by carrying out Steps I to IV, nickel particles having an average particle size of 150 nm or less, a sharp particle size distribution, a small CV value, and excellent dispersibility are stably produced. be able to. More specifically, by carrying out Steps I to IV, nickel particles containing nickel element as a main component, containing copper element, and having the above configurations a to d can be produced. Since the copper element is diffused inside the nickel particles having the configurations a to d, it is presumed that the nickel magnetism is relaxed, the aggregation due to the magnetism is suppressed, and the dispersibility is improved.
このようなニッケル粒子を用いて製造される導電性ペーストは、例えばＭＬＣＣ等の内部電極の形成に使用する場合、電極層の表面（誘電体層との境界面）の凹凸の発生を防ぎ、平坦化できることから、電極層の薄層化及び多層化が容易であり、電気的な信頼性も向上させることができる。従って、本実施の形態のニッケル粒子は、例えば積層セラミックスコンデンサ（ＭＬＣＣ）の内部電極形成用導電性ペースト、電力用半導体素子の接合材料などの電子材料として好適に利用できる。 When the conductive paste produced by using such nickel particles is used for forming an internal electrode such as MLCC, the surface of the electrode layer (the interface with the dielectric layer) is prevented from being uneven and is flat. Therefore, the electrode layer can be easily thinned and multi-layered, and the electrical reliability can be improved. Therefore, the nickel particles of the present embodiment can be suitably used as an electronic material such as a conductive paste for forming an internal electrode of a laminated ceramic capacitor (MLCC) and a bonding material for a power semiconductor element.
［積層セラミックコンデンサ用の内部電極］
本実施の形態の積層セラミックコンデンサ用の内部電極（以下、単に「内部電極」ともいう。）は、本実施の形態のニッケル粒子をペースト化し、セラミック基板上に印刷することで製造される。
前記ペースト化する際、有機ビヒクル、水系ビヒクル等の公知の粘度調整剤を混合させても良い。粘度調整剤を混合することで、前記ペーストに適度な流動性や揮発性が付与され、セラミック基板上に平滑な内部電極を形成することができる。
有機ビヒクルは、例えば、樹脂を有機溶剤中に溶解したものである。有機ビヒクルに用いる樹脂は特に限定されず、エチルセルロース、ポリビニルブチラール等の通常の各種樹脂から適宜選択すればよい。また、用いる有機溶剤も特に限定されず、印刷法やシート法など、利用する方法に応じて、テルピネオール、ブチルカルビトール、アセトン、トルエン等の各種有機溶剤から適宜選択すればよい。
また、水系ビヒクルは、例えば、ポリビニルアルコール、セルロース、水溶性アクリル樹脂が挙げられる。
セラミック基板は、公知のものが用いられ、例えば、ペロブスカイト系の誘電体で、チタン酸バリウムや、そのチタンの一部がジルコンに置換したもの、バリウムの一部がストロンチウムやカルシウム等に置換した誘電体が挙げられる。
内部電極の印刷方法は、層を均一に形成できる方法であれば特に限定されず、例えば、スクリーン印刷法、グラビア印刷法、蒸着法、スパッタリング法、インクジェット法が挙げられる。
[Internal electrodes for multilayer ceramic capacitors]
The internal electrode for the multilayer ceramic capacitor of the present embodiment (hereinafter, also simply referred to as “internal electrode”) is manufactured by pasting the nickel particles of the present embodiment and printing them on a ceramic substrate.
At the time of making the paste, a known viscosity modifier such as an organic vehicle or an aqueous vehicle may be mixed. By mixing the viscosity modifier, appropriate fluidity and volatility are imparted to the paste, and a smooth internal electrode can be formed on the ceramic substrate.
The organic vehicle is, for example, a resin dissolved in an organic solvent. The resin used for the organic vehicle is not particularly limited, and may be appropriately selected from various ordinary resins such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent to be used is not particularly limited, and various organic solvents such as terpineol, butyl carbitol, acetone, and toluene may be appropriately selected depending on the method to be used such as a printing method and a sheet method.
Examples of the water-based vehicle include polyvinyl alcohol, cellulose, and water-soluble acrylic resin.
Known ceramic substrates are used. For example, perovskite-based dielectrics such as barium titanate, a part of titanium replaced with zircon, and a part of barium replaced with strontium, calcium, etc. The body is mentioned.
The printing method of the internal electrode is not particularly limited as long as it can form a uniform layer, and examples thereof include a screen printing method, a gravure printing method, a vapor deposition method, a sputtering method, and an inkjet method.
［積層セラミックコンデンサ］
本実施の形態の積層セラミックコンデンサは、前記内部電極とセラミックス誘電体とを交互に層状に重ねて圧着し、焼成して一体化させることに製造される。
セラミックス誘導体は、公知のものが用いられ、前記のチタン酸バリウム等が挙げられる。これをペースト化し、前記内部電極上に層を形成する。ペースト化する際、有機ビヒクル、水系ビヒクル等の公知の粘度調整剤を混合させても良い。粘度調整剤を混合することで、前記ペーストに適度な流動性や揮発性が付与され、セラミック基板上に平滑な内部電極を形成することができる。有機ビヒクルは、例えば、樹脂を有機溶剤中に溶解したものである。有機ビヒクルに用いる樹脂は特に限定されず、エチルセルロース、ポリビニルブチラール等の通常の各種樹脂から適宜選択すればよい。また、用いる有機溶剤も特に限定されず、印刷法やシート法など、利用する方法に応じて、テルピネオール、ブチルカルビトール、アセトン、トルエン等の各種有機溶剤から適宜選択すればよい。
また、水系ビヒクルは、例えば、ポリビニルアルコール、セルロース、水溶性アクリル樹脂が挙げられる。
セラミックス誘電体の印刷方法は、層を均一に形成できる方法であれば特に限定されず、例えば、スクリーン印刷法、グラビア印刷法、蒸着法、スパッタリング法、インクジェット法が挙げられる。
内部電極とセラミックス誘導体の層及び層厚は限定しないが、例えば、数層〜１０００層であり、各層厚が、０．１μｍ〜２μｍである。
次に、このようにして得られた、内部電極とセラミックス誘導体の多層構造を、圧着し一体成型し、所定の大きさ（チップのサイズ）にカットし、焼成してチップを形成する。焼成温度は、例えば１０００℃〜１３００℃である。焼成後、チップの両端面に金属ペーストを塗布、熱処理し、その表面にメッキをすることで、外部電極を形成する。
[Multilayer ceramic capacitor]
The multilayer ceramic capacitor of the present embodiment is manufactured by alternately stacking the internal electrodes and ceramic dielectrics in layers, crimping them, and firing them to integrate them.
Known ceramic derivatives are used, and examples thereof include the above-mentioned barium titanate. This is made into a paste to form a layer on the internal electrode. When forming a paste, a known viscosity modifier such as an organic vehicle or an aqueous vehicle may be mixed. By mixing the viscosity modifier, appropriate fluidity and volatility are imparted to the paste, and a smooth internal electrode can be formed on the ceramic substrate. The organic vehicle is, for example, a resin dissolved in an organic solvent. The resin used for the organic vehicle is not particularly limited, and may be appropriately selected from various ordinary resins such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent to be used is not particularly limited, and various organic solvents such as terpineol, butyl carbitol, acetone, and toluene may be appropriately selected depending on the method to be used such as a printing method and a sheet method.
Examples of the water-based vehicle include polyvinyl alcohol, cellulose, and water-soluble acrylic resin.
The printing method of the ceramic dielectric is not particularly limited as long as it can form a uniform layer, and examples thereof include a screen printing method, a gravure printing method, a vapor deposition method, a sputtering method, and an inkjet method.
The layer and layer thickness of the internal electrode and the ceramic derivative are not limited, but are, for example, several layers to 1000 layers, and each layer thickness is 0.1 μm to 2 μm.
Next, the multilayer structure of the internal electrode and the ceramic derivative thus obtained is pressure-bonded, integrally molded, cut into a predetermined size (chip size), and fired to form a chip. The firing temperature is, for example, 1000 ° C to 1300 ° C. After firing, a metal paste is applied to both end faces of the chip, heat treatment is performed, and the surface is plated to form an external electrode.
このようにして製造された本発明の実施形態に係る積層セラミックコンデンサは、ハンダ付等によりプリント基板上などに実装され、各種電子機器等に使用される。
このような電子機器は、本発明のニッケル粒子を使用しているため、小型高容量化が可能であり、信頼性、高寿命性に優れ、電子部品の高温負荷寿命を向上させることができる。
The multilayer ceramic capacitor according to the embodiment of the present invention manufactured in this manner is mounted on a printed circuit board or the like by soldering or the like, and is used in various electronic devices and the like.
Since such electronic devices use the nickel particles of the present invention, they can be made smaller and have a higher capacity, are excellent in reliability and long life, and can improve the high temperature load life of electronic components.
以下、本発明を実施例により具体的に説明するが、本発明はこれらの実施例によって何ら限定されるものではない。なお、以下の実施例において、特にことわりのない限り各種測定、評価は下記によるものである。 Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.
［粒子径及び粒度分布の測定］
ＳＥＭにより試料の写真を撮影して、その中から無作為に４０００個のニッケル粒子を抽出してそれぞれの面積を求め、真球に換算したときの粒子径を個数基準として、一次粒子の９０％径Ｄ９０及び平均粒子径（メディアン径）Ｄ５０を算出した。なお、Ｄ５０が７０ｎｍ以上の場合はＳＥＭの倍率を５万倍として、７０ｎｍ未満の場合はＳＥＭの倍率を１０万倍として、無作為に８視野以上撮影した。
また、ＣＶ値（変動係数）は、（一次粒子径の標準偏差）÷（Ｄ５０）によって算出した。ＣＶ値が小さいほど、粒子径がより均一であることを示す。
[Measurement of particle size and particle size distribution]
A photograph of the sample is taken by SEM, 4000 nickel particles are randomly extracted from the sample, the area of each is calculated, and 90% of the primary particles are based on the particle size when converted to a true sphere. The diameter D 90 and the average particle diameter (median diameter) D 50 were calculated. When D 50 was 70 nm or more, the SEM magnification was 50,000 times, and when it was less than 70 nm, the SEM magnification was 100,000 times, and 8 or more fields of view were randomly photographed.
The CV value (coefficient of variation) was calculated by (standard deviation of primary particle size) ÷ (D 50 ). The smaller the CV value, the more uniform the particle size.
［粗大粒子及び最大粒子径の確認］
ＳＥＭにより試料の写真を撮影して、その中から無作為に１００００個のニッケル粒子を抽出して、その中で、Ｄ５０の２倍以上のニッケル粒子の個数を求めた。また、最大粒子径Ｄｍａｘを求めた。なお、Ｄ５０が７０ｎｍ以上の場合はＳＥＭの倍率を２万倍として、７０ｎｍ未満の場合はＳＥＭの倍率を５万倍として、無作為に１０視野以上撮影した。
[Confirmation of coarse particles and maximum particle size]
By taking a sample photo by SEM, and extracts random 10000 nickel particles from them in that, to determine the number of more than twice the nickel particles of D 50. Moreover, the maximum particle diameter D max was determined. When D 50 was 70 nm or more, the SEM magnification was 20,000 times, and when it was less than 70 nm, the SEM magnification was 50,000 times, and 10 or more fields of view were randomly photographed.
［元素分析］
ニッケル粒子の金属元素成分の含有量は、ＩＣＰ（誘導結合プラズマ発光分光分析法）で測定した。また、金属元素以外の成分の含有量は、元素分析装置ＦＬＡＳＨ２０００（ジェイサイエンスラボ製）で測定した。
[Elemental analysis]
The content of the metal element component of the nickel particles was measured by ICP (inductively coupled plasma emission spectroscopy). The content of components other than metal elements was measured with an elemental analyzer FLASH2000 (manufactured by J-Science Lab).
［ニッケル粒子表面の有機物分析］
ソックスレー抽出器を用いて、２ｇの乾燥したニッケル粒子を、２００ｍｌのトルエンで、１２時間抽出を行った。そして、得られた抽出液を、ＧＣ−ＭＳ（ＧＣユニット ６８９０Ｎ Ａｇｉｌｅｎｔ Ｔｅｃｈｎｏｌｏｇｉｅｓ製、ＭＳユニット ＪＭＳ−Ｋ９ 日本電子製）で測定し、ニッケル粒子表面に付着している有機物を分析した。
[Analysis of organic matter on the surface of nickel particles]
Using a Soxhlet extractor, 2 g of dried nickel particles were extracted with 200 ml of toluene for 12 hours. Then, the obtained extract was measured by GC-MS (GC unit 6890N Agilent Technologies, MS unit JMS-K9 JEOL Ltd.), and the organic substances adhering to the surface of the nickel particles were analyzed.
［重量減少率の測定］
示差熱天秤Ｒ−ＴＧ−ＤＴＡ／Ｈ８１２０（リガク製）を用いて、昇温速度１５℃／分で測定した。なお、不活性雰囲気下の測定は、窒素雰囲気下で測定し、還元雰囲気下の測定は、水素−窒素の混合ガス雰囲気（水素は３％）下で測定した。
[Measurement of weight loss rate]
Measurement was performed at a heating rate of 15 ° C./min using a differential thermal balance R-TG-DTA / H8120 (manufactured by Rigaku). The measurement under the inert atmosphere was performed under the nitrogen atmosphere, and the measurement under the reducing atmosphere was performed under the mixed gas atmosphere of hydrogen and nitrogen (hydrogen is 3%).
［表面平滑性］
ニッケル粒子Ａ〜Ｅについては、ニッケル粒子合成後の反応液（ニッケル粒子スラリー）に対し、トルエン洗浄と遠心分離を５回繰り返し行った後、エバポレーターでトルエンを一部除去して、スラリー中のニッケル粒子が５０質量％になるまで濃縮した。この濃縮物をガラス板上に塗布して、８０℃で乾燥後、接触式の表面粗さ計で算術平均粗さＲａを測定した。
ニッケル粒子Ｆについては、乾燥したニッケル粒子を、超音波ホモジナイザーを用いてトルエンに分散させてスラリー状にした後、エバポレーターでトルエンを一部除去して、スラリー中のニッケル粒子が５０質量％になるまで濃縮した。この濃縮物をガラス板上に塗布して、８０℃で乾燥後、接触式の表面粗さ計で算術平均粗さＲａを測定した。
[Surface smoothness]
For nickel particles A to E, the reaction solution (nickel particle slurry) after nickel particle synthesis was repeatedly washed with toluene and centrifuged five times, and then a part of toluene was removed with an evaporator to remove nickel in the slurry. The particles were concentrated to 50% by weight. This concentrate was applied onto a glass plate, dried at 80 ° C., and then the arithmetic average roughness Ra was measured with a contact-type surface roughness meter.
Regarding the nickel particles F, the dried nickel particles are dispersed in toluene using an ultrasonic homogenizer to form a slurry, and then a part of the toluene is removed by an evaporator to make the nickel particles in the slurry 50% by mass. Concentrated to. This concentrate was applied onto a glass plate, dried at 80 ° C., and then the arithmetic average roughness Ra was measured with a contact-type surface roughness meter.
［ニッケル粒子の合成］
実施例１〜４及び比較例１のニッケル粒子は、以下の工程I〜工程IVを通して合成した。この合成方法は、本発明のニッケル粒子を製造する方法の一例であり、製造方法は限定しない。
工程I：種粒子を形成する工程
工程II：ニッケル錯体溶液を準備する工程
工程III：前記種粒子と前記ニッケル錯体溶液とを混合して混合液を得る工程
工程IV：前記混合液中のニッケルイオンを加熱還元し、前記種粒子を核として金属ニッケルを析出・成長させてニッケル粒子を形成する工程
また、比較例２におけるニッケル粒子は、ＪＦＥミネラル製 ＮＦＰ２０１Ｓ（平均粒子径：２００ｎｍ）を用いた。
[Synthesis of nickel particles]
The nickel particles of Examples 1 to 4 and Comparative Example 1 were synthesized through the following steps I to IV. This synthesis method is an example of a method for producing nickel particles of the present invention, and the production method is not limited.
Step I: Forming seed particles Step II: Preparing a nickel complex solution Step III: Mixing the seed particles with the nickel complex solution to obtain a mixed solution Step IV: Nickel ions in the mixed solution Was heated and reduced to form nickel particles by precipitating and growing metallic nickel around the seed particles as nuclei. Further, as the nickel particles in Comparative Example 2, NFP201S (average particle diameter: 200 nm) manufactured by JFE Mineral was used.
＜工程I＞
（実施例１〜４及び比較例１）
６．０ｋｇのオレイルアミンに７０ｇのギ酸銅四水和物と３５０ｇのギ酸ニッケル二水和物を加え、窒素フロー下で１２０℃、６０分間加熱することでギ酸銅とギ酸ニッケルをオレイルアミンに溶解した。
<Process I>
(Examples 1 to 4 and Comparative Example 1)
70 g of copper formate tetrahydrate and 350 g of nickel formate dihydrate were added to 6.0 kg of oleylamine, and copper formate and nickel formate were dissolved in oleylamine by heating at 120 ° C. for 60 minutes under a nitrogen flow.
上記の溶解液にマイクロ波を照射して１９０℃、１０分間加熱して、６．１ｋｇのニッケル粒子スラリー（１−Ａ）を調製した。得られたニッケル粒子スラリー（１−Ａ）の１００ｇを分取して、上澄み液を取り除いた後、トルエンとメタノールを用いてそれぞれ２回洗浄した後、６０℃に維持される真空乾燥機で６時間乾燥してニッケル種粒子ａを調製した。 The above solution was irradiated with microwaves and heated at 190 ° C. for 10 minutes to prepare 6.1 kg of nickel particle slurry (1-A). 100 g of the obtained nickel particle slurry (1-A) was separated, the supernatant was removed, and the mixture was washed twice with toluene and methanol, respectively, and then in a vacuum dryer maintained at 60 ° C. 6 Nickel seed particles a were prepared by drying for hours.
ニッケル種粒子ａのＳＥＭ写真を参照すると、ニッケル種粒子ａの平均粒子径は１５ｎｍ、ＣＶ値は０．１４、銅元素の含有量は１５．０６質量％であった。 With reference to the SEM photograph of the nickel seed particle a, the average particle diameter of the nickel seed particle a was 15 nm, the CV value was 0.14, and the copper element content was 15.06 mass%.
＜工程II＞
（実施例１〜４及び比較例１）
５０．１ｋｇのオレイルアミンに２０．６ｋｇの酢酸ニッケル四水和物を加え、窒素フロー下で１４０℃、４時間加熱することでニッケル錯体溶液（２−Ａ）を調製した。
<Process II>
(Examples 1 to 4 and Comparative Example 1)
A nickel complex solution (2-A) was prepared by adding 20.6 kg of nickel acetate tetrahydrate to 50.1 kg of oleylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
＜工程III＞
（実施例１）
２５．０ｇの（１−Ａ）及び、１０５０ｇの（２−Ａ）を、反応容器中で撹拌し、混合液Ａを得た。
（実施例２及び比較例１）
２５０ｇの（１−Ａ）及び、１０５００ｇの（２−Ａ）を、反応容器中で撹拌し、混合液Ｂ、Ｅを得た。
（実施例３）
１０００ｇの（１−Ａ）及び、１０１３０ｇの（２−Ａ）を、反応容器中で撹拌し、混合液Ｃを得た。
（実施例４）
２５００ｇの（１−Ａ）及び、８０００ｇの（２−Ａ）を、反応容器中で撹拌し、混合液Ｄを得た。
<Process III>
(Example 1)
25.0 g (1-A) and 1050 g (2-A) were stirred in a reaction vessel to obtain a mixture A.
(Example 2 and Comparative Example 1)
250 g (1-A) and 10500 g (2-A) were stirred in a reaction vessel to obtain mixtures B and E.
(Example 3)
1000 g (1-A) and 10130 g (2-A) were stirred in a reaction vessel to obtain a mixture C.
(Example 4)
2500 g (1-A) and 8000 g (2-A) were stirred in the reaction vessel to obtain a mixture D.
＜工程IV＞
（実施例１）
混合液Ａを、撹拌しながら、オイルバスで、２３５℃、１５分間加熱することによって、ニッケル粒子スラリーＡを得た。このニッケル粒子スラリーＡを静置分離し、上澄み液を取り除いた後、トルエン及びメタノールを用いてそれぞれ２回洗浄し、真空乾燥機で６０℃、６時間乾燥して、ニッケル粒子Ａを得た。このニッケル粒子の物性を表１〜４に示した。また、実施例１で得たニッケル粒子のＳＥＭ写真を図１に示した。図１から、実施例１で得たニッケル粒子は、粗大粒子が観察されず、粒子径がほぼ揃っていた。
<Process IV>
(Example 1)
The mixture A was heated in an oil bath at 235 ° C. for 15 minutes with stirring to obtain a nickel particle slurry A. The nickel particle slurry A was separated by allowing it to stand, and the supernatant was removed. Then, the nickel particle slurry A was washed twice with toluene and methanol, and dried in a vacuum dryer at 60 ° C. for 6 hours to obtain nickel particles A. The physical properties of these nickel particles are shown in Tables 1 to 4. Moreover, the SEM photograph of the nickel particles obtained in Example 1 is shown in FIG. From FIG. 1, the nickel particles obtained in Example 1 had no coarse particles observed and had substantially the same particle size.
（実施例２、３及び４）
それぞれ別個の反応容器中の混合液Ｂ、Ｃ、Ｄを、マイクロ波を照射して、２３５℃、１５分間加熱することによって、ニッケル粒子スラリーＢ、Ｃ、Ｄを得た。これらのニッケル粒子スラリーを静置分離し、上澄み液を取り除いた後、トルエン及びメタノールを用いてそれぞれ２回洗浄し、真空乾燥機で６０℃、６時間乾燥して、ニッケル粒子Ｂ、Ｃ、Ｄを得た。これらのニッケル粒子の物性を表１〜４に示した。
(Examples 2, 3 and 4)
Nickel particle slurries B, C and D were obtained by irradiating the mixed solutions B, C and D in separate reaction vessels with microwaves and heating them at 235 ° C. for 15 minutes. These nickel particle slurries were separated by allowing them to stand, and after removing the supernatant, they were washed twice with toluene and methanol, respectively, and dried in a vacuum dryer at 60 ° C. for 6 hours to obtain nickel particles B, C, D. Got The physical properties of these nickel particles are shown in Tables 1 to 4.
（比較例１）
反応容器中の混合液Ｅを、マイクロ波を照射して、２８０℃、３０分間加熱した他は、実施例２と同様にして、ニッケル粒子スラリーＥ及びニッケル粒子Ｅを得た。ニッケル粒子Ｅの物性を表１〜４に示した。
(Comparative Example 1)
Nickel particle slurry E and nickel particles E were obtained in the same manner as in Example 2 except that the mixed solution E in the reaction vessel was irradiated with microwaves and heated at 280 ° C. for 30 minutes. The physical properties of the nickel particles E are shown in Tables 1 to 4.
以上、本発明の実施の形態を例示の目的で詳細に説明したが、本発明は上記実施の形態に制約されることはなく、種々の変形が可能である。 Although the embodiments of the present invention have been described in detail for the purpose of exemplification, the present invention is not limited to the above embodiments and can be modified in various ways.
Claims (11)
走査型電子顕微鏡観察により測定された、前記ニッケル粒子の一次粒子の平均粒子径Ｄ５０が２０ｎｍ〜１５０ｎｍであり、一次粒子径の変動係数が、０．２以下であり、前記平均粒子径Ｄ５０の２．０倍以上の粒子が、全粒子個数の０．１％以下であるニッケル粒子。 The content of the metal element component is 85 to 99% by mass, the content of the component other than the metal element is 1 to 12% by mass , and the nickel element is contained in the metal element component in an amount of 80% by mass or more. Nickel particles containing 20% by mass or less of one or more metal elements selected from copper, silver, gold, platinum or palladium .
The average particle size D 50 of the primary particles of the nickel particles measured by scanning electron microscope observation is 20 nm to 150 nm, the coefficient of variation of the primary particle size is 0.2 or less, and the average particle size D 50. The number of particles 2.0 times or more of the total number of particles is 0.1% or less of the total number of particles.
A multilayer ceramic capacitor in which the internal electrodes according to claim 10 and ceramic dielectrics are alternately layered and pressure-bonded, fired and integrated.
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| JP6546309B1 (en) * | 2018-03-19 | 2019-07-17 | 株式会社ノリタケカンパニーリミテド | Conductive paste with stable viscosity over time |
| KR102147408B1 (en) * | 2018-08-23 | 2020-08-24 | 삼성전기주식회사 | Multi-layered ceramic electronic component and method for manufacturing the same |
| JP7157597B2 (en) * | 2018-08-31 | 2022-10-20 | 花王株式会社 | Water-based fine metal particle dispersion |
| KR20200064350A (en) * | 2018-11-29 | 2020-06-08 | 솔브레인 주식회사 | Method for manufacturing conductive ink composition for internal electrode of multilayer ceramic capacitor and method for manufacturing internal electrode of multilayer ceramic capacitor using the same |
| CN116981526A (en) | 2021-04-26 | 2023-10-31 | 三井金属矿业株式会社 | Nickel powder and method for producing nickel particles |
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| KR102292897B1 (en) * | 2014-04-08 | 2021-08-24 | 도호 티타늄 가부시키가이샤 | Nickel powder |
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