WO2015098284A1 - タングステンコンデンサ用陽極体の製造方法 - Google Patents
タングステンコンデンサ用陽極体の製造方法 Download PDFInfo
- Publication number
- WO2015098284A1 WO2015098284A1 PCT/JP2014/078951 JP2014078951W WO2015098284A1 WO 2015098284 A1 WO2015098284 A1 WO 2015098284A1 JP 2014078951 W JP2014078951 W JP 2014078951W WO 2015098284 A1 WO2015098284 A1 WO 2015098284A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- tungsten
- dielectric layer
- sintered body
- powder
- alkoxide compound
- Prior art date
Links
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 239000003990 capacitor Substances 0.000 title claims abstract description 41
- 229910052721 tungsten Inorganic materials 0.000 title claims abstract description 38
- 239000010937 tungsten Substances 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000010410 layer Substances 0.000 claims abstract description 61
- 229910052751 metal Inorganic materials 0.000 claims abstract description 48
- 239000002184 metal Substances 0.000 claims abstract description 48
- -1 alkoxide compound Chemical class 0.000 claims abstract description 40
- 239000002344 surface layer Substances 0.000 claims abstract description 15
- 239000000126 substance Substances 0.000 claims abstract description 13
- 238000005245 sintering Methods 0.000 claims abstract description 12
- 238000004455 differential thermal analysis Methods 0.000 claims abstract description 7
- 239000010936 titanium Substances 0.000 claims description 29
- 229910052719 titanium Inorganic materials 0.000 claims description 24
- 238000004519 manufacturing process Methods 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 18
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 14
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 5
- 238000004458 analytical method Methods 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 23
- 239000000843 powder Substances 0.000 description 22
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten trioxide Chemical compound O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 description 20
- JMXKSZRRTHPKDL-UHFFFAOYSA-N titanium ethoxide Chemical compound [Ti+4].CC[O-].CC[O-].CC[O-].CC[O-] JMXKSZRRTHPKDL-UHFFFAOYSA-N 0.000 description 13
- 150000004703 alkoxides Chemical class 0.000 description 11
- 238000010438 heat treatment Methods 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- 230000036571 hydration Effects 0.000 description 9
- 238000006703 hydration reaction Methods 0.000 description 9
- 239000002245 particle Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- CMPGARWFYBADJI-UHFFFAOYSA-L tungstic acid Chemical compound O[W](O)(=O)=O CMPGARWFYBADJI-UHFFFAOYSA-L 0.000 description 7
- 229910044991 metal oxide Inorganic materials 0.000 description 6
- 150000004706 metal oxides Chemical class 0.000 description 6
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 6
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 5
- 150000001875 compounds Chemical class 0.000 description 5
- 238000003795 desorption Methods 0.000 description 5
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 239000012298 atmosphere Substances 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000012300 argon atmosphere Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 239000011863 silicon-based powder Substances 0.000 description 3
- 238000003980 solgel method Methods 0.000 description 3
- 229910001930 tungsten oxide Inorganic materials 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- WQJQOUPTWCFRMM-UHFFFAOYSA-N tungsten disilicide Chemical compound [Si]#[W]#[Si] WQJQOUPTWCFRMM-UHFFFAOYSA-N 0.000 description 2
- 229910021342 tungsten silicide Inorganic materials 0.000 description 2
- OFEAOSSMQHGXMM-UHFFFAOYSA-N 12007-10-2 Chemical compound [W].[W]=[B] OFEAOSSMQHGXMM-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- HHFAWKCIHAUFRX-UHFFFAOYSA-N ethoxide Chemical compound CC[O-] HHFAWKCIHAUFRX-UHFFFAOYSA-N 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004949 mass spectrometry Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- IKNCGYCHMGNBCP-UHFFFAOYSA-N propan-1-olate Chemical compound CCC[O-] IKNCGYCHMGNBCP-UHFFFAOYSA-N 0.000 description 1
- HKJYVRJHDIPMQB-UHFFFAOYSA-N propan-1-olate;titanium(4+) Chemical compound CCCO[Ti](OCCC)(OCCC)OCCC HKJYVRJHDIPMQB-UHFFFAOYSA-N 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 235000010215 titanium dioxide Nutrition 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/0029—Processes of manufacture
- H01G9/0032—Processes of manufacture formation of the dielectric layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
- C23C18/1208—Oxides, e.g. ceramics
- C23C18/1216—Metal oxides
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/125—Process of deposition of the inorganic material
- C23C18/1254—Sol or sol-gel processing
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
- C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
- C23C18/125—Process of deposition of the inorganic material
- C23C18/1295—Process of deposition of the inorganic material with after-treatment of the deposited inorganic material
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/02—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using non-aqueous solutions
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/20—Electrolytic after-treatment
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/24—Chemical after-treatment
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/26—Anodisation of refractory metals or alloys based thereon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/07—Dielectric layers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
- B22F2003/241—Chemical after-treatment on the surface
- B22F2003/242—Coating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/20—Refractory metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
Definitions
- the present invention relates to a method for manufacturing an anode body of a capacitor made of a tungsten sintered body. More specifically, the present invention relates to a method for manufacturing an anode body of a tungsten capacitor with reduced capacitance change (bias voltage dependency) with respect to a direct current (DC) voltage, and a method for manufacturing a solid electrolytic capacitor.
- a solid electrolytic capacitor has, for example, a conductive body (anode body) made of a sintered body of valve foil metal powder such as aluminum foil, tantalum, niobium, tungsten, etc. as one electrode, and the surface layer of the electrode is an electrolyte such as phosphoric acid. It is composed of a metal oxide dielectric layer formed on the surface by electrolytic oxidation in an aqueous solution and the other electrode (semiconductor layer) composed of a semiconductor layer formed thereon by electrolytic polymerization or the like.
- an electrolytic capacitor using a sintered body of tungsten powder as an anode body is more resistant to DC voltage than an electrolytic capacitor using an aluminum foil and a sintered body of tantalum powder or niobium powder as an anode body.
- An object of the present invention is to provide an anode body of a tungsten capacitor with reduced capacitance change (bias voltage dependency) with respect to a DC voltage in an electrolytic capacitor using the sintered body of tungsten powder as an anode body, and the anode body. It is providing the electrolytic capacitor using this.
- anode body for an electrolytic capacitor in which a sintered body (anode body) obtained by sintering tungsten powder is formed and a dielectric layer is formed on the surface.
- a sintered body anode body obtained by sintering tungsten powder
- a dielectric layer is formed on the surface.
- this invention relates to the manufacturing method of the anode body of the following tungsten capacitor, and the manufacturing method of a solid electrolytic capacitor.
- a sintering process for forming a sintered body of tungsten powder, a chemical conversion process for forming a dielectric layer on the surface of the sintered body, and an alkoxide compound of the dielectric layer and the valve metal after forming the dielectric layer The ratio of the mass loss at 100 to 300 ° C. in the differential thermal analysis of the sintered body on which the dielectric layer is formed to the mass before the analysis is 0.
- a method for producing an anode body for a capacitor characterized by being performed so as to be 0.02% or less.
- valve metal alkoxide compound is a titanium alkoxide compound or a tungsten alkoxide compound.
- a sintering process for forming a sintered body of tungsten powder, a chemical conversion process for forming a dielectric layer on the surface of the sintered body, and a valve metal other than the dielectric layer and tungsten after the formation of the dielectric layer A step of bringing the alkoxide compound into contact with the alkoxide compound, wherein the ratio of the number of valve metal atoms other than tungsten to tungsten atoms in the surface layer of the dielectric layer is 0.05 to 0.35.
- a process for producing a capacitor anode body characterized in that: [4] A sintering process for forming a sintered body of tungsten powder, a chemical conversion process for forming a dielectric layer on the surface of the sintered body, and a valve metal other than the dielectric layer and tungsten after the formation of the dielectric layer A step of contacting the alkoxide compound with a mass reduction at 100 to 300 ° C. in a differential thermal analysis of the sintered body on which the dielectric layer is formed relative to the mass before the analysis.
- the capacitor is characterized in that the ratio is 0.02% or less, and the atomic ratio of valve metal atoms other than tungsten to tungsten atoms in the surface layer of the dielectric layer is 0.05 to 0.35.
- a method for producing an anode body [5] The method for producing an anode body for a capacitor as described in [3] or [4] above, wherein the alkoxide compound of the valve metal other than tungsten is an alkoxide compound of titanium. [6] A method for producing a solid electrolytic capacitor using the method for producing an anode body according to any one of 1 to 5 above.
- the present invention provides a method for manufacturing an anode body in which a dielectric layer is processed with a valve metal alkoxide in the manufacture of a capacitor anode body in which a dielectric layer made of a tungsten oxide compound is formed by forming a tungsten sintered body.
- the capacitor using the anode body according to the manufacturing method of the present invention can be preferably used in a circuit for precision equipment because the fluctuation of the capacitor capacity (bias voltage dependency) with respect to DC is low.
- tungsten powder raw tungsten powder, hereinafter referred to as “primary powder” as a raw material of the tungsten sintered body is commercially available with a lower limit of the average particle size of up to about 0.5 ⁇ m.
- the tungsten powder can produce a sintered body (anode) with smaller pores as the particle size is smaller.
- Tungsten powder with a particle size smaller than that of commercially available products can be obtained by pulverizing tungsten trioxide powder in a hydrogen atmosphere, or by using a reducing agent such as hydrogen or sodium for tungstic acid or tungsten halide. It can be obtained by appropriately selecting and reducing. It can also be obtained by obtaining directly from a tungsten-containing mineral or a plurality of steps, and selecting and reducing the conditions.
- the tungsten powder as a raw material may be granulated (hereinafter, the granulated tungsten powder may be simply referred to as “granulated powder”).
- Granulated powder is preferable because it has good fluidity and is easy to perform operations such as molding.
- the granulated powder described above may be prepared by adjusting the pore distribution by the same method as disclosed in JP 2003-213302 A for niobium powder, for example.
- the granulated powder can also be obtained, for example, by adding at least one liquid such as water or liquid resin to the primary powder to form granules of an appropriate size, and then heating and sintering under reduced pressure.
- Easy to handle granulated granulated powder under reduced pressure conditions for example, 10 kPa or less in a non-oxidizing gas atmosphere such as hydrogen
- high temperature conditions for example, 1100 to 2600 ° C., 0.1 to 100 hours
- Such granulated powder can be classified by sieving to make the particle size uniform. If the average particle size is preferably in the range of 50 to 200 ⁇ m, more preferably 100 to 200 ⁇ m, it is convenient for smooth flow from the hopper of the molding machine to the mold.
- the capacity of the electrolytic capacitor made from the granulated powder can be particularly increased.
- the specific surface area (by the BET method) of the granulated powder is preferably 0.2 to 20 m 2 / g, more preferably 1.
- the capacity of the electrolytic capacitor can be increased, which is preferable.
- the tungsten material may contain some impurities described later.
- tungsten powder having tungsten silicide in the surface layer so that the silicon content is in a specific range is preferably used.
- the tungsten powder having tungsten silicide in the surface layer is mixed with, for example, 0.05 to 7% by mass of silicon powder and heated under reduced pressure to react at 1100 to 2600 ° C. or in a hydrogen stream. After pulverizing tungsten with, and further mixing silicon powder, it can be prepared by heating at 1100-2600 ° C. under reduced pressure for reaction.
- tungsten powder those having at least one selected from tungsten nitride, tungsten carbide, and tungsten boride in the surface layer are also preferably used.
- the above tungsten powder is preferably formed into a molded body having a density of 8 g / cm 3 or more, and the molded body is preferably heated at a temperature of 1480 to 2600 ° C., preferably for 10 minutes to 100 hours.
- a sintered body is formed (sintering process).
- the surface layer of the sintered body is subjected to electrolytic oxidation (chemical conversion) in an aqueous electrolyte solution (chemical conversion step).
- tungsten oxide (VI) that is, tungsten trioxide (WO 3 ) is formed on the surface of the sintered body (outer surface and inner surface of the void portion), and this becomes a dielectric coating (dielectric layer).
- the three in the tungsten oxide compound in addition to WO 3, tungstic acid (e.g., H 2 WO 4, H 4 WO 5) the WO 3 is a hydrated compound hydrated water with exists.
- Tungsten trioxide (WO 3 ) is industrially produced by thermally decomposing tungstic acid in the atmosphere at 900 to 1000 K (powder powder metallurgy glossary, page 312, Nikkan Kogyo Shimbun, 2001). ). Tungstic acid is also commercially available as a powder.
- H 2 WO 4 , H 4 WO 5 and the like which are hydrated compounds of tungsten trioxide (WO 3 ), are formed during the chemical conversion.
- the inventors of the present invention have immersed a tungsten anode body in which a dielectric layer is formed in an ethanol solution of titanium ethoxide for 1 hour, that is, performed a process of bringing the dielectric layer into contact with an alkoxide compound of titanium.
- the capacitance at the bias voltage of 3V was almost the same as the capacitance at the bias voltage of 0V, and it was confirmed that the bias dependence as normally seen was not observed. It was also confirmed that when titanium ethoxide was allowed to act, titanium (IV) oxide was generated on the surface layer of the dielectric coating.
- the surface layer said here is an area
- the reason why the hydration water exists and causes the bias voltage dependency is that, for example, a dielectric made of tungstic acid has a distortion in symmetry due to the presence of hydration water and exhibits spontaneous polarization. Conceivable. On the other hand, it is considered that tungsten trioxide from which hydration water has been removed has no distortion in symmetry and does not exhibit bias voltage dependency.
- titanium tetraethoxide titanium tethoxide
- titanium tetraisopropoxide titanium isopropoxide
- titanium tetrabutoxide titanium butoxide
- Titanium ethoxide and titanium propoxide are liquid at room temperature, and can be suitably acted upon by immersing the anode body, and can be appropriately diluted with ethanol, so that ethoxide and propoxide are preferred. It is preferable that the titanium alkoxide compound solution is easily used before it is immersed in absolute ethanol before the anode body is immersed.
- titanium remains in the dielectric coating as an oxide.
- the hydrated compound of tungsten trioxide has a great influence on the capacitor characteristics, the amount of titanium oxide is very small, and titanium is a valve metal, and the influence of the oxide on the capacitor characteristics is small.
- the temperature for immersing in the titanium alkoxide solution may be at least the melting point of the titanium alkoxide compound and the solvent and less than the boiling point. From the viewpoint of ease of handling, it is preferable to act at room temperature, and from the viewpoint of accelerating the reaction, it can be carried out by heating to about 50 to 70 ° C.
- the treatment time can be appropriately adjusted according to the temperature. If it is too short, there is no effect, but if it is too long, the effect is not added.
- the anode body after the titanium alkoxide treatment is preferably subjected to heat treatment.
- the heat treatment temperature is preferably 100 to 250 ° C, more preferably 160 to 230 ° C.
- the alkoxide compound used by embodiment of this invention is not limited to this,
- the alkoxide compound of a valve metal can be used.
- examples of the valve metal include aluminum, tantalum, niobium, titanium, hafnium, vanadium, zirconium, zinc, molybdenum, tungsten, bismuth, and antimony.
- a tungsten alkoxide compound, which is the same metal as the anode body, is preferable, and a titanium alkoxide compound is preferable because the oxide has a high dielectric constant and is easy to handle.
- the hydrolysis reaction of metal alkoxide compounds is used for the synthesis of metal oxides by the sol-gel method.
- the metal alkoxide deprives the hydrated water of the hydrated compound of tungsten trioxide in the dielectric layer and hydrolyzes it, and the metal oxide is finally converted by heating through a reaction similar to the sol-gel method. It is thought that it is generated and remains in the dielectric layer.
- the metal of the metal alkoxide is a valve metal
- the generated metal oxide becomes an oxide of the valve metal, so that the characteristics as a capacitor are not impaired.
- the higher the dielectric constant of the metal oxide that is produced the higher the dielectric constant of tungsten trioxide is not impaired.
- the hydration water of the hydrated compound of tungsten trioxide in the dielectric layer is removed by performing the treatment of bringing the dielectric layer of the tungsten anode body into contact with the metal alkoxide compound.
- the degree of removal of the hydrated water can be evaluated by differential thermal analysis (TG-DTA).
- TG-DTA differential thermal analysis
- the mass reduction at room temperature ⁇ 100 °C (W RT -W 100 ) corresponds to a desorption amount of adsorbed water
- mass loss at 100 ⁇ 300 °C (W 100 -W 300) is de-waters of hydration This is considered to correspond to the separation amount (amount of hydrated water remaining in the dielectric layer). Therefore, the remaining amount of hydrated water in the dielectric layer can be known from the ratio of mass reduction at 100 to 300 ° C. with respect to the mass before heating “(W 100 ⁇ W 300 ) / W RT ”.
- the value of (W 100 -W 300 ) / W RT (mass reduction rate) needs to be 0.02% or less for the dielectric layer of the anode body treated with the metal alkoxide. It is. When this value exceeds 0.02%, the bias voltage dependency of the capacity increases.
- metal atoms of the metal alkoxide finally remain on the surface of the dielectric layer.
- the atomic ratio of metal atoms derived from metal alkoxide and tungsten atoms remaining in the surface layer of the dielectric layer is determined by X-ray photoelectron spectroscopy (XPS) as described later. Can be measured.
- the metal alkoxide treatment is performed so that the atomic ratio of the metal atom to the tungsten atom (the number of metal atoms / the number of tungsten atoms) is in the range of 0.05 to 0.35. Do. When the ratio of the number of metal atoms to tungsten atoms is less than 0.05, the capacity dependency of the bias voltage increases.
- the (W 100 -W 300 ) / W RT value (mass reduction rate) of the anode dielectric layer treated with metal alkoxide is 0.02% or less.
- the atomic ratio of the metal alkoxide-derived metal atoms and tungsten atoms remaining on the surface of the dielectric layer is in the range of 0.05 to 0.35. Treatment with metal alkoxide is performed.
- Ti / W ratio When the XPS spectrum of the anode dielectric layer was measured using an XPS analyzer (Shimadzu Corporation AXIS-NOVA), most of titanium ( ⁇ i) was tetravalent. The atomic ratio was calculated from the peak intensity ratio with the peak near 35 eV as the hexavalent tungsten peak and the peak near 460 eV as the tetravalent titanium peak. Further, by analyzing the dielectric layer while performing argon etching, it was found that titanium exists in a range from the particle surface of the granulated powder to 30 nm. When argon etching was performed, partial reduction occurred and the peak position changed.
- the detection depth without etching was about 15 nm, and it was assumed that the atomic ratio did not change up to a depth of 30 nm. Note that the Ti peak is weak because the number of atoms is small, and overlaps with the W background, so the measured value has an error of calculated value ⁇ 0.05.
- Examples 1-5, Comparative Examples 1-2 A commercial tungsten powder with a volume average particle size of 0.65 ⁇ m was left in a vacuum furnace at 1400 ° C. for 30 minutes and then taken out to room temperature to break up the agglomerate to produce a granulated powder with a volume average particle size of 75 ⁇ m did. This powder was formed by planting a tantalum wire having a diameter of 0.29 mm using a molding machine, and further sintered in a vacuum furnace at 1470 ° C.
- An 80% by volume solution was prepared by adding absolute ethanol as a solvent to titanium ethoxide.
- the formed sintered body was immersed in a titanium ethoxide solution stirred with a magnetic stirrer under an argon atmosphere under the temperature and time conditions described in Examples 1 to 5 and Comparative Example 1 in Table 1. After removing from the titanium ethoxide solution, it was dried at 190 ° C. for 30 minutes in an argon atmosphere and washed with ethanol. 50 masses of the formed sintered body (anode body) prepared in each Example and Comparative Example 1 and the formed sintered body (anode body) of Comparative Example 2 that was not immersed in the titanium ethoxide solution.
- Capacitor capacity was measured with 0%, 2V, and 3V bias voltages using a 1% sulfuric acid aqueous solution as an electrolyte.
- Table 1 shows the measurement results (average value of 30 samples for each example) together with the presence or absence of mass loss determined by TG-DTA and the Ti / W atomic ratio (average value of 2 samples for each example) determined from XPS measurement. Show.
- “mass loss by TG-DTA” is the ratio of the mass reduction at 100 to 300 ° C. with respect to the mass before heating (the value of (W 100 ⁇ W 300 ) / W RT described above) is 0. The case of 02% or less is indicated as “none”, and the case of exceeding 0.02% is indicated as “present”.
- Example 1 commercial tungsten powder was mixed with 0.4 mass% of commercially available silicon powder having an average particle size of 1 ⁇ m to produce granulated powder at 1450 ° C., and further, the sintering temperature was changed to 1540 ° C. Sintering was carried out in the same manner as in Example 1. Further, in Example 1, conversion was performed in the same manner as in Example 1 except that 4% by mass of potassium persulfate aqueous solution was used as a chemical conversion solution, and the initial current density per sintered body was 5 mA, the voltage was 15 V, and the temperature was 40 ° C. went.
- Example 2 shows the measurement results (average value of 30 samples for each example) together with the presence or absence of mass loss determined by TG-DTA and the Ti / W atomic ratio (average value of 2 samples for each example) determined from XPS measurement. Show. The notation of “mass loss by TG-DTA” in the table is the same as in Table 1.
- the anode body processed under the conditions of the example has a smaller capacity change when a DC bias voltage is applied than the anode body processed under the conditions of the comparative example. Good results were shown.
- the anode body treated under the conditions of the example shows no mass reduction corresponding to desorption of hydrated water as evaluated by TG-DTA, and the water in the dielectric layer is treated by treatment with titanium alkoxide. It can be seen that the Japanese water has been removed. Further, the bias voltage dependency is small when the atomic ratio Ti / W of titanium to tungsten in the surface layer of the dielectric layer is 0.05 to 0.35 (considering an error of 0.05). was gotten.
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Abstract
Description
固体電解コンデンサは、例えば、アルミニウム箔や、タンタル、ニオブ、タングステンなどの弁作用金属粉の焼結体からなる導電体(陽極体)を一方の電極とし、その電極の表層をリン酸などの電解質水溶液中で電解酸化して表面に形成した金属酸化物の誘電体層とその上に電解重合等により形成した半導体層からなる他方の電極(半導体層)とで構成される。
[1]タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層と弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層が形成された焼結体についての示差熱分析における100~300℃での質量減少の当該分析前の質量に対する割合が0.02%以下となるように行うことを特徴とするコンデンサの陽極体の製造方法。
[2]前記弁金属のアルコキシド化合物がチタンのアルコキシド化合物またはタングステンのアルコキシド化合物である前項1に記載のコンデンサの陽極体の製造方法。
[3]タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層とタングステン以外の弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層の表層中におけるタングステン原子に対するタングステン以外の弁金属原子の原子数比が0.05~0.35となるように行うことを特徴とするコンデンサ陽極体の製造方法。
[4]タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層とタングステン以外の弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層が形成された焼結体についての示差熱分析における100~300℃での質量減少の当該分析前の質量に対する割合が0.02%以下となり、かつ前記誘電体層の表層中におけるタングステン原子に対するタングステン以外の弁金属原子の原子数比が0.05~0.35となるように行うことを特徴とするコンデンサ陽極体の製造方法。
[5]前記タングステン以外の弁金属のアルコキシド化合物がチタンのアルコキシド化合物である前項3または4に記載のコンデンサの陽極体の製造方法。
[6]前項1~5のいずれかに記載の陽極体の製造方法を用いる固体電解コンデンサの製造方法。
本発明の製造方法による陽極体を用いたコンデンサは、DCに対するコンデンサ容量の変動(バイアス電圧依存性)が低いため精密機器用の回路に好ましく使用できる。
また、タングステン含有鉱物から直接または複数の工程を得て、条件を選択して還元することによっても得ることもできる。
前述の造粒粉は、例えばニオブ粉について特開2003-213302号公報に開示されている方法と同様の方法により細孔分布を調整したものでもよい。
このような造粒粉は、ふるいで分級して粒径を揃えることができる。平均粒径が好ましくは50~200μm、より好ましくは100~200μmの範囲であれば、成形機のホッパーから金型にスムーズに流れるために好都合である。
このような造粒粉を得る場合、例えば、前記一次粒子径を調整して、造粒粉の比表面積(BET法による)が、好ましくは0.2~20m2/g、より好ましくは1.5~20m2/gになるようにすると、電解コンデンサの容量をより大きくすることができ好ましい。
例えば、ケイ素含有量が特定の範囲となるよう表層中にケイ化タングステンとしたタングステン粉が好ましく用いられる。表層中にケイ化タングステンとしたタングステン粉は、例えばタングステン粉に0.05~7質量%のケイ素粉を混合し、減圧下で加熱して1100~2600℃で反応させることにより、あるいは水素気流中でタングステンを粉砕後、さらに、ケイ素粉を混合した後、減圧下で1100~2600℃の温度にて加熱して反応させることにより調製することができる。
次いで、焼結体の表層を電解質水溶液中にて電解酸化(化成)する(化成工程)。この化成により、焼結体の表面(外表面と空孔部の内表面)に酸化タングステン(VI)つまり三酸化タングステン(WO3)が形成され、これが誘電体被膜(誘電体層)となる。
チタンエトキシドを作用させると、誘電体被膜の表層に酸化チタン(IV)が生じていることも確認された。なお、ここで言う表層とは、後述のように、誘電体被膜(誘電体層)の表面から30nmの深さまでの領域である。また、チタンエトキシドで処理を行った陽極体について、後述する示差熱質量分析(TG-DTA)で加熱時の質量減少を調べたところ、水和水の脱離に相当する質量減少は確認できなかった。すなわち、化成後にチタンエトキシドを作用させることにより、誘電体層中に存在するタングステン酸から水和水が除去された三酸化タングステン(WO3)となることによりコンデンサとしての特性が良くなっていると考えられる。また、チタンエトキシド処理を行うと水和水が脱離するが、大気下放置しても吸着水が付着することはあっても、再び水和水が入って特性を落とすことはない。
陽極体を浸漬させる前に予め無水エタノールに浸漬させておくとチタンアルコキシド化合物溶液がなじみやすく好ましい。
処理時間は温度に応じて適宜調節することができる。短すぎると効果がないが、長すぎても効果は上乗せされない。
チタンアルコキシド処理後の陽極体は熱処理を行うことが好ましい。熱処理温度は100~250℃が好ましく、160~230℃がより好ましい。
陽極体の誘電体層から水和水が除去されたことの確認は、示差熱分析(TG-DTA)によりアルゴン雰囲気で陽極体を300℃まで加熱して行った。ここで、前述のように、室温から100℃における質量減少は吸着水の脱離量に相当し、100℃から300℃における質量減少がタングステン酸の水和水の脱離量に相当するとした。そして、加熱前の陽極体の質量に対する100~300℃での質量減少の割合(質量減少率)を求めた。
XPS分析装置(島津製作所AXIS-NOVA)を用いて陽極体誘電体層のXPSスペクトルを測定したところ、チタン(Тi)の殆どは4価であった。35eV付近のピークを6価のタングステンピークとして、460eV付近のピークを4価のチタンピークとしてピークの強度比から原子数比を算出した。また、誘電体層をアルゴンエッチングしながら分析することにより、チタンは造粒粉の粒子表面から30nmまでの範囲に存在することが分かった。アルゴンエッチングすると部分的に還元され、ピーク位置が変化した。エッチングなしの状態での検出深さは15nm程度であり、30nmの深さまで原子数比は変わらないものと仮定した。なお、Tiのピークは原子数が少ないため弱く、かつWのバックグラウンドに重なるため測定値には算出値±0.05の誤差がある。
体積平均粒子径0.65μmの市販タングステン粉を1400℃で30分、真空炉中に放置した後に室温に取り出して得た塊状物を解砕して、体積平均粒子径75μmの造粒粉を作製した。この粉を成形機を使用して直径0.29mmのタンタル線を植立させて成形し、さらに1470℃で20分真空炉中で焼結して、大きさ1.0×3.0×4.4mm(質量120mg、タンタル線は、1.0×3.0mmの面中央で内部に3.4mm侵入し、外部に6mm突出している)の焼結体を1000個作製した。3質量%の過硫酸アンモニウム水溶液を化成液として、焼結体1個あたり初期電流密度2mA、電圧10V、温度50℃で5時間化成し、焼結体の表面(外表面と空孔部の内表面)に誘電体層を形成し、水洗、次いでエタノール洗浄し、化成済み焼結体を作製した。チタンエトキシドに無水エタノールを溶媒として加えて80体積%溶液を作製した。表1の実施例1~5及び比較例1に記載した温度及び時間条件でアルゴン雰囲気下マグネティックスターラーで撹拌したチタンエトキシド溶液に化成済み焼結体を浸漬させた。チタンエトキシド溶液から取り出した後、アルゴン雰囲気下190℃で30分間乾燥させ、エタノール洗浄した。
各実施例及び比較例1で作製した化成済み焼結体(陽極体)、及びチタンエトキシド溶液への浸漬処理を行わなかった比較例2の化成済み焼結体(陽極体)について、50質量%の硫酸水溶液を電解液として、0V、2V、3Vの各バイアス電圧でコンデンサ容量を測定した。この測定結果(各例30個の平均値)を、TG-DTAにより調べた質量減少の有無、XPS測定から求めたTi/Wの原子数比(各例2個の平均値)と共に表1に示す。なお、表中の「TG-DTAでの質量減少」は、加熱前の質量に対する100~300℃における質量減少分の割合(前述の(W100-W300)/WRTの値)が0.02%以下の場合を「なし」と表記し、0.02%を超える場合を「あり」と表記している。
実施例1で、市販のタングステン粉に平均粒径1μmの市販ケイ素粉を0.4質量%混合して1450℃で造粒粉を作製し、さらに、焼結温度を1540℃にした以外は実施例1と同様にして焼結を行った。また、実施例1で、4質量%の過硫酸カリウム水溶液を化成液として、焼結体1個あたり初期電流密度5mA、電圧15V、温度40℃とした以外は実施例1と同様にして化成を行った。続いて、実施例1で、チタンアルコキシドとしてチタンイソプロポキシドを用いた以外は実施例1と同様にして、表2の実施例6~9及び比較例3、4に記載した処理条件でチタンアルコキシドによる処理を行った。その後、各バイアス電圧での容量を測定した。この測定結果(各例30個の平均値)を、TG-DTAにより調べた質量減少の有無、XPS測定から求めたTi/Wの原子数比(各例2個の平均値)と共に表2に示す。なお、表中の「TG-DTAでの質量減少」の表記については表1と同様である。
Claims (6)
- タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層と弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層が形成された焼結体についての示差熱分析における100~300℃での質量減少の当該分析前の質量に対する割合が0.02%以下となるように行うことを特徴とするコンデンサの陽極体の製造方法。
- 前記弁金属のアルコキシド化合物がチタンのアルコキシド化合物またはタングステンのアルコキシド化合物である請求項1に記載のコンデンサの陽極体の製造方法。
- タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層とタングステン以外の弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層の表層中におけるタングステン原子に対するタングステン以外の弁金属原子の原子数比が0.05~0.35となるように行うことを特徴とするコンデンサ陽極体の製造方法。
- タングステン粉の焼結体を形成する焼結工程、前記焼結体の表面に誘電体層を形成する化成工程、及び前記誘電体層の形成後に当該誘電体層とタングステン以外の弁金属のアルコキシド化合物とを接触させる処理工程を有し、前記処理工程を、前記誘電体層が形成された焼結体についての示差熱分析における100~300℃での質量減少の当該分析前の質量に対する割合が0.02%以下となり、かつ前記誘電体層の表層中におけるタングステン原子に対するタングステン以外の弁金属原子の原子数比が0.05~0.35となるように行うことを特徴とするコンデンサ陽極体の製造方法。
- 前記タングステン以外の弁金属のアルコキシド化合物がチタンのアルコキシド化合物である請求項3または4に記載のコンデンサの陽極体の製造方法。
- 請求項1~5のいずれかに記載の陽極体の製造方法を用いる固体電解コンデンサの製造方法。
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JPH0442519A (ja) * | 1990-06-08 | 1992-02-13 | Toyo Alum Kk | アルミニウム電解コンデンサの電極およびその製造方法 |
JP2002158141A (ja) * | 2000-11-20 | 2002-05-31 | Hitachi Maxell Ltd | 電気化学キャパシタ用の電極材料、およびこれを用いた電気化学キャパシタ、ならびにその電極材料の製造方法 |
JP2013530908A (ja) * | 2010-04-22 | 2013-08-01 | ビーエーエスエフ ソシエタス・ヨーロピア | グラフェンに基づいた2次元サンドウィッチナノ材料の製造方法 |
JP2013232403A (ja) * | 2012-04-06 | 2013-11-14 | Semiconductor Energy Lab Co Ltd | 蓄電装置用負極、その製造方法及び蓄電装置 |
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JPH0442519A (ja) * | 1990-06-08 | 1992-02-13 | Toyo Alum Kk | アルミニウム電解コンデンサの電極およびその製造方法 |
JP2002158141A (ja) * | 2000-11-20 | 2002-05-31 | Hitachi Maxell Ltd | 電気化学キャパシタ用の電極材料、およびこれを用いた電気化学キャパシタ、ならびにその電極材料の製造方法 |
JP2013530908A (ja) * | 2010-04-22 | 2013-08-01 | ビーエーエスエフ ソシエタス・ヨーロピア | グラフェンに基づいた2次元サンドウィッチナノ材料の製造方法 |
JP2013232403A (ja) * | 2012-04-06 | 2013-11-14 | Semiconductor Energy Lab Co Ltd | 蓄電装置用負極、その製造方法及び蓄電装置 |
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