EP4166690A1 - Electroless gold plating bath - Google Patents
Electroless gold plating bath Download PDFInfo
- Publication number
- EP4166690A1 EP4166690A1 EP22197168.2A EP22197168A EP4166690A1 EP 4166690 A1 EP4166690 A1 EP 4166690A1 EP 22197168 A EP22197168 A EP 22197168A EP 4166690 A1 EP4166690 A1 EP 4166690A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- good good
- electroless
- plating film
- gold
- gold plating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000007747 plating Methods 0.000 title claims abstract description 345
- 239000010931 gold Substances 0.000 title claims abstract description 203
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 197
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 197
- 150000002429 hydrazines Chemical class 0.000 claims abstract description 22
- SRCZENKQCOSNAI-UHFFFAOYSA-H gold(3+);trisulfite Chemical compound [Au+3].[Au+3].[O-]S([O-])=O.[O-]S([O-])=O.[O-]S([O-])=O SRCZENKQCOSNAI-UHFFFAOYSA-H 0.000 claims abstract description 17
- IBVAQQYNSHJXBV-UHFFFAOYSA-N adipic acid dihydrazide Chemical compound NNC(=O)CCCCC(=O)NN IBVAQQYNSHJXBV-UHFFFAOYSA-N 0.000 claims abstract description 10
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine hydrate Chemical compound O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims abstract description 10
- XSXYESVZDBAKKT-UHFFFAOYSA-N 2-hydroxybenzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1O XSXYESVZDBAKKT-UHFFFAOYSA-N 0.000 claims abstract description 5
- QSBINWBNXWAVAK-PSXMRANNSA-N PE-NMe(16:0/16:0) Chemical compound CCCCCCCCCCCCCCCC(=O)OC[C@H](COP(O)(=O)OCCNC)OC(=O)CCCCCCCCCCCCCCC QSBINWBNXWAVAK-PSXMRANNSA-N 0.000 claims abstract description 5
- QYCSNMDOZNUZIT-UHFFFAOYSA-N benzhydrylidenehydrazine Chemical compound C=1C=CC=CC=1C(=NN)C1=CC=CC=C1 QYCSNMDOZNUZIT-UHFFFAOYSA-N 0.000 claims abstract description 5
- PRBLRLQZOKOQCQ-UHFFFAOYSA-N benzylhydrazine;hydron;chloride Chemical compound Cl.NNCC1=CC=CC=C1 PRBLRLQZOKOQCQ-UHFFFAOYSA-N 0.000 claims abstract description 5
- PTYMQUSHTAONGW-UHFFFAOYSA-N carbonic acid;hydrazine Chemical compound NN.OC(O)=O PTYMQUSHTAONGW-UHFFFAOYSA-N 0.000 claims abstract description 5
- ZWLIYXJBOIDXLL-UHFFFAOYSA-N decanedihydrazide Chemical compound NNC(=O)CCCCCCCCC(=O)NN ZWLIYXJBOIDXLL-UHFFFAOYSA-N 0.000 claims abstract description 5
- GRGBENNNGZARRZ-UHFFFAOYSA-N dodecanedihydrazide Chemical compound NNC(=O)CCCCCCCCCCC(=O)NN GRGBENNNGZARRZ-UHFFFAOYSA-N 0.000 claims abstract description 5
- KJDJPXUIZYHXEZ-UHFFFAOYSA-N hydrogen sulfate;methylaminoazanium Chemical compound CN[NH3+].OS([O-])(=O)=O KJDJPXUIZYHXEZ-UHFFFAOYSA-N 0.000 claims abstract description 5
- ILULYDJFTJKQAP-UHFFFAOYSA-N hydron;propan-2-ylhydrazine;chloride Chemical compound [Cl-].CC(C)N[NH3+] ILULYDJFTJKQAP-UHFFFAOYSA-N 0.000 claims abstract description 5
- HKOOXMFOFWEVGF-UHFFFAOYSA-N phenylhydrazine Chemical compound NNC1=CC=CC=C1 HKOOXMFOFWEVGF-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229940067157 phenylhydrazine Drugs 0.000 claims abstract description 5
- DXGIRFAFSFKYCF-UHFFFAOYSA-N propanehydrazide Chemical compound CCC(=O)NN DXGIRFAFSFKYCF-UHFFFAOYSA-N 0.000 claims abstract description 5
- FUSNOPLQVRUIIM-UHFFFAOYSA-N 4-amino-2-(4,4-dimethyl-2-oxoimidazolidin-1-yl)-n-[3-(trifluoromethyl)phenyl]pyrimidine-5-carboxamide Chemical compound O=C1NC(C)(C)CN1C(N=C1N)=NC=C1C(=O)NC1=CC=CC(C(F)(F)F)=C1 FUSNOPLQVRUIIM-UHFFFAOYSA-N 0.000 claims abstract description 4
- BIVUUOPIAYRCAP-UHFFFAOYSA-N aminoazanium;chloride Chemical compound Cl.NN BIVUUOPIAYRCAP-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000012493 hydrazine sulfate Substances 0.000 claims abstract description 4
- 229910000377 hydrazine sulfate Inorganic materials 0.000 claims abstract description 4
- LIAWOTKNAVAKCX-UHFFFAOYSA-N hydrazine;dihydrochloride Chemical compound Cl.Cl.NN LIAWOTKNAVAKCX-UHFFFAOYSA-N 0.000 claims abstract description 4
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 claims abstract 4
- 238000005260 corrosion Methods 0.000 claims description 48
- 239000008139 complexing agent Substances 0.000 claims description 39
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 32
- 239000003795 chemical substances by application Substances 0.000 claims description 29
- 150000001412 amines Chemical class 0.000 claims description 25
- 235000010323 ascorbic acid Nutrition 0.000 claims description 20
- 229960005070 ascorbic acid Drugs 0.000 claims description 20
- 239000011668 ascorbic acid Substances 0.000 claims description 20
- 150000000996 L-ascorbic acids Chemical class 0.000 claims description 15
- RHUYHJGZWVXEHW-UHFFFAOYSA-N 1,1-Dimethyhydrazine Chemical compound CN(C)N RHUYHJGZWVXEHW-UHFFFAOYSA-N 0.000 claims description 5
- JYSUYJCLUODSLN-UHFFFAOYSA-N 1,3-benzothiazol-2-ylhydrazine Chemical compound C1=CC=C2SC(NN)=NC2=C1 JYSUYJCLUODSLN-UHFFFAOYSA-N 0.000 claims description 4
- GBHCABUWWQUMAJ-UHFFFAOYSA-N 2-hydrazinoethanol Chemical compound NNCCO GBHCABUWWQUMAJ-UHFFFAOYSA-N 0.000 claims description 4
- IOMZCWUHFGMSEJ-UHFFFAOYSA-N 4-(azaniumylamino)benzenesulfonate Chemical compound NNC1=CC=C(S(O)(=O)=O)C=C1 IOMZCWUHFGMSEJ-UHFFFAOYSA-N 0.000 claims description 4
- OFLXLNCGODUUOT-UHFFFAOYSA-N acetohydrazide Chemical compound C\C(O)=N\N OFLXLNCGODUUOT-UHFFFAOYSA-N 0.000 claims description 4
- WARCRYXKINZHGQ-UHFFFAOYSA-N benzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1 WARCRYXKINZHGQ-UHFFFAOYSA-N 0.000 claims description 4
- VYSYZMNJHYOXGN-UHFFFAOYSA-N ethyl n-aminocarbamate Chemical compound CCOC(=O)NN VYSYZMNJHYOXGN-UHFFFAOYSA-N 0.000 claims description 4
- WFJRIDQGVSJLLH-UHFFFAOYSA-N methyl n-aminocarbamate Chemical compound COC(=O)NN WFJRIDQGVSJLLH-UHFFFAOYSA-N 0.000 claims description 4
- MLSJBGYKDYSOAE-DCWMUDTNSA-N L-Ascorbic acid-2-glucoside Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O[C@@H]2[C@@H]([C@@H](O)[C@H](O)[C@@H](CO)O2)O)=C1O MLSJBGYKDYSOAE-DCWMUDTNSA-N 0.000 claims description 3
- 229940078752 magnesium ascorbyl phosphate Drugs 0.000 claims description 3
- YRWWOAFMPXPHEJ-OFBPEYICSA-K sodium L-ascorbic acid 2-phosphate Chemical compound [Na+].[Na+].[Na+].OC[C@H](O)[C@H]1OC(=O)C(OP([O-])([O-])=O)=C1[O-] YRWWOAFMPXPHEJ-OFBPEYICSA-K 0.000 claims description 3
- 229940048058 sodium ascorbyl phosphate Drugs 0.000 claims description 3
- HTJNEBVCZXHBNJ-XCTPRCOBSA-H trimagnesium;(2r)-2-[(1s)-1,2-dihydroxyethyl]-3,4-dihydroxy-2h-furan-5-one;diphosphate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.OC[C@H](O)[C@H]1OC(=O)C(O)=C1O HTJNEBVCZXHBNJ-XCTPRCOBSA-H 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 76
- 125000003289 ascorbyl group Chemical class [H]O[C@@]([H])(C([H])([H])O*)[C@@]1([H])OC(=O)C(O*)=C1O* 0.000 abstract 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 112
- 239000000758 substrate Substances 0.000 description 60
- 229910052759 nickel Inorganic materials 0.000 description 56
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 52
- 230000008021 deposition Effects 0.000 description 52
- -1 sodium gold sulfite) Chemical compound 0.000 description 30
- 229910052763 palladium Inorganic materials 0.000 description 26
- 239000003638 chemical reducing agent Substances 0.000 description 23
- 230000007797 corrosion Effects 0.000 description 20
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 19
- 235000019345 sodium thiosulphate Nutrition 0.000 description 19
- 238000007772 electroless plating Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 230000015572 biosynthetic process Effects 0.000 description 14
- 238000011156 evaluation Methods 0.000 description 14
- OAKJQQAXSVQMHS-UHFFFAOYSA-N hydrazine Substances NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 14
- 229910000838 Al alloy Inorganic materials 0.000 description 10
- 229910000881 Cu alloy Inorganic materials 0.000 description 10
- WPPDFTBPZNZZRP-UHFFFAOYSA-N aluminum copper Chemical compound [Al].[Cu] WPPDFTBPZNZZRP-UHFFFAOYSA-N 0.000 description 10
- OFNHPGDEEMZPFG-UHFFFAOYSA-N phosphanylidynenickel Chemical compound [P].[Ni] OFNHPGDEEMZPFG-UHFFFAOYSA-N 0.000 description 10
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 10
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 10
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 9
- 229940074404 sodium succinate Drugs 0.000 description 9
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 description 9
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 description 8
- 239000011574 phosphorus Substances 0.000 description 7
- 229910052698 phosphorus Inorganic materials 0.000 description 7
- 101100133719 Caenorhabditis elegans npr-18 gene Proteins 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 229910000531 Co alloy Inorganic materials 0.000 description 5
- 229910052697 platinum Inorganic materials 0.000 description 5
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- LGRDPUAPARTXMG-UHFFFAOYSA-N bismuth nickel Chemical compound [Ni].[Bi] LGRDPUAPARTXMG-UHFFFAOYSA-N 0.000 description 3
- ZDQYSKICYIVCPN-UHFFFAOYSA-L sodium succinate (anhydrous) Chemical compound [Na+].[Na+].[O-]C(=O)CCC([O-])=O ZDQYSKICYIVCPN-UHFFFAOYSA-L 0.000 description 3
- ZWZLRIBPAZENFK-UHFFFAOYSA-J sodium;gold(3+);disulfite Chemical compound [Na+].[Au+3].[O-]S([O-])=O.[O-]S([O-])=O ZWZLRIBPAZENFK-UHFFFAOYSA-J 0.000 description 3
- VILCJCGEZXAXTO-UHFFFAOYSA-N 2,2,2-tetramine Chemical compound NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 description 2
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 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
- CPJYFACXEHYLFS-UHFFFAOYSA-N [B].[W].[Co] Chemical compound [B].[W].[Co] CPJYFACXEHYLFS-UHFFFAOYSA-N 0.000 description 2
- FEBFYWHXKVOHDI-UHFFFAOYSA-N [Co].[P][W] Chemical compound [Co].[P][W] FEBFYWHXKVOHDI-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- UYMKPFRHYYNDTL-UHFFFAOYSA-N ethenamine Chemical compound NC=C UYMKPFRHYYNDTL-UHFFFAOYSA-N 0.000 description 2
- 150000002344 gold compounds Chemical class 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- LSHROXHEILXKHM-UHFFFAOYSA-N n'-[2-[2-[2-(2-aminoethylamino)ethylamino]ethylamino]ethyl]ethane-1,2-diamine Chemical compound NCCNCCNCCNCCNCCN LSHROXHEILXKHM-UHFFFAOYSA-N 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 150000003464 sulfur compounds Chemical class 0.000 description 2
- FAGUFWYHJQFNRV-UHFFFAOYSA-N tetraethylenepentamine Chemical compound NCCNCCNCCNCCN FAGUFWYHJQFNRV-UHFFFAOYSA-N 0.000 description 2
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 2
- AFBBKYQYNPNMAT-UHFFFAOYSA-N 1h-1,2,4-triazol-1-ium-3-thiolate Chemical compound SC=1N=CNN=1 AFBBKYQYNPNMAT-UHFFFAOYSA-N 0.000 description 1
- JVVRJMXHNUAPHW-UHFFFAOYSA-N 1h-pyrazol-5-amine Chemical compound NC=1C=CNN=1 JVVRJMXHNUAPHW-UHFFFAOYSA-N 0.000 description 1
- NSPMIYGKQJPBQR-UHFFFAOYSA-N 4H-1,2,4-triazole Chemical compound C=1N=CNN=1 NSPMIYGKQJPBQR-UHFFFAOYSA-N 0.000 description 1
- KLSJWNVTNUYHDU-UHFFFAOYSA-N Amitrole Chemical compound NC1=NC=NN1 KLSJWNVTNUYHDU-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 229910001152 Bi alloy Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- PQUCIEFHOVEZAU-UHFFFAOYSA-N Diammonium sulfite Chemical compound [NH4+].[NH4+].[O-]S([O-])=O PQUCIEFHOVEZAU-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- XYXNTHIYBIDHGM-UHFFFAOYSA-N ammonium thiosulfate Chemical compound [NH4+].[NH4+].[O-]S([O-])(=O)=S XYXNTHIYBIDHGM-UHFFFAOYSA-N 0.000 description 1
- 239000012964 benzotriazole Substances 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 125000004093 cyano group Chemical group *C#N 0.000 description 1
- FGRVOLIFQGXPCT-UHFFFAOYSA-L dipotassium;dioxido-oxo-sulfanylidene-$l^{6}-sulfane Chemical compound [K+].[K+].[O-]S([O-])(=O)=S FGRVOLIFQGXPCT-UHFFFAOYSA-L 0.000 description 1
- WPUMTJGUQUYPIV-JIZZDEOASA-L disodium (S)-malate Chemical compound [Na+].[Na+].[O-]C(=O)[C@@H](O)CC([O-])=O WPUMTJGUQUYPIV-JIZZDEOASA-L 0.000 description 1
- ZUDYLZOBWIAUPC-UHFFFAOYSA-L disodium;pentanedioate Chemical compound [Na+].[Na+].[O-]C(=O)CCCC([O-])=O ZUDYLZOBWIAUPC-UHFFFAOYSA-L 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002762 monocarboxylic acid derivatives Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 1
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
- BHZRJJOHZFYXTO-UHFFFAOYSA-L potassium sulfite Chemical compound [K+].[K+].[O-]S([O-])=O BHZRJJOHZFYXTO-UHFFFAOYSA-L 0.000 description 1
- 235000019252 potassium sulphite Nutrition 0.000 description 1
- NGXSWUFDCSEIOO-UHFFFAOYSA-N pyrrolidin-3-amine Chemical compound NC1CCNC1 NGXSWUFDCSEIOO-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 235000019265 sodium DL-malate Nutrition 0.000 description 1
- HELHAJAZNSDZJO-OLXYHTOASA-L sodium L-tartrate Chemical compound [Na+].[Na+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O HELHAJAZNSDZJO-OLXYHTOASA-L 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- 239000001394 sodium malate Substances 0.000 description 1
- PRWXGRGLHYDWPS-UHFFFAOYSA-L sodium malonate Chemical compound [Na+].[Na+].[O-]C(=O)CC([O-])=O PRWXGRGLHYDWPS-UHFFFAOYSA-L 0.000 description 1
- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 description 1
- 229940039790 sodium oxalate Drugs 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 239000001433 sodium tartrate Substances 0.000 description 1
- 229960002167 sodium tartrate Drugs 0.000 description 1
- 235000011004 sodium tartrates Nutrition 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000010186 staining Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 description 1
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical compound [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 description 1
- 229940038773 trisodium citrate Drugs 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
Classifications
-
- 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
- C23C18/16—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 reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
-
- 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
- C23C18/16—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 reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
- C23C18/44—Coating with noble metals using reducing agents
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- 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
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
- C23F11/14—Nitrogen-containing compounds
- C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom
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- 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
- C23C18/16—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 reduction or substitution, e.g. electroless plating
- C23C18/1601—Process or apparatus
- C23C18/1633—Process of electroless plating
- C23C18/1646—Characteristics of the product obtained
- C23C18/165—Multilayered product
- C23C18/1651—Two or more layers only obtained by electroless plating
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- 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
- C23C18/16—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 reduction or substitution, e.g. electroless plating
- C23C18/18—Pretreatment of the material to be coated
- C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
Definitions
- the present disclosure relates to an electroless gold plating bath.
- Gold has high electrical conductivity next to silver and copper, and is excellent in physical properties such as connectivity in thermocompression bonding, and is also excellent in chemical properties such as oxidation resistance and chemical resistance. Therefore, gold plating with gold is widely used as a final surface treatment method for circuits on printed wiring boards, mounting portions and terminal portions of IC packages, and the like in the field of the electronics industry. In recent years, along with the improvement of electronic components to be smaller and denser, electroless plating methods attaining excellent functionality without the need of lead wiring have been used preferably.
- an Electroless Nickel Immersion Gold (ENIG) process.
- ENIG Electroless Nickel Immersion Gold
- ENEPIG Electroless Nickel Electroless Palladium Immersion Gold
- ENEPIG Electroless Nickel Electroless Palladium Immersion Gold
- an electroless gold plating bath which contains a water-soluble gold compound, a complexing agent, and a reducing agent as well as polyvinyl alcohol and/or polyvinylpyrrolidone added as a stabilizer. It is described that such a configuration makes it possible to form a good gold plating film only in metal portions and is preferably applicable to gold plating for ceramics IC, packages, and the like (For example, see Japanese Patent No.2927142 ).
- an object of the present disclosure is to provide an electroless gold plating bath, which is capable of forming a uniform gold plating film with a sufficient thickness in one step in both the ENIG process and the ENEPIG process.
- the electroless gold plating bath of the present disclosure includes a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,
- an electroless gold plating bath which is capable of forming a uniform gold plating film with a sufficient thickness in one step in both the ENIG process and the ENEPIG process.
- the electroless gold plating bath of the present disclosure is an electroless gold plating bath including a gold sulfite as a gold source, a thiosulfate as a complexing agent, ascorbic acid compounds as a reducing agent, and hydrazine compounds as a reducing agent.
- the electroless gold plating bath of the present disclosure is a cyanide-free bath (non-cyanide bath), and includes, as the gold source, gold sulfite (e.g., sodium gold sulfite), which is a water-soluble gold compound with no cyano group.
- gold sulfite e.g., sodium gold sulfite
- the concentration of the gold sulfite in the plating bath may be preferably 0.5 g/L to 2 g/L based on gold.
- a concentration of the gold sulfite of less than 0.5 g/L would result in a low plating deposition rate, while a concentration of the gold sulfite of more than 2 g/L would result in a poor adhesion of the gold plating film to the electroless nickel plating film.
- the complexing agent is used to stabilize the solubility of gold in the electroless gold plating bath.
- the electroless gold plating bath of the present disclosure includes a sulfur compound as the complexing agent.
- the sulfur compound may be a thiosulfate (such as sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, or the like) a sulfite (such as sodium sulfite, potassium sulfite, ammonium sulfite, or the like).
- thiosulfate such as sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, or the like
- a sulfite such as sodium sulfite, potassium sulfite, ammonium sulfite, or the like.
- the concentration of the thiosulfate (which may be thiosulfates) in the plating bath may be in a range of 0.5 g/L to 10 g/L, preferably. If the concentration of the thiosulfate is less than 0.5 g/L. the effect of the complexing agent would be insufficient, and if the concentration of the thiosulfate is greater than 10 g/L, local corrosion of the electroless nickel plating film would be increased, which would cause a gap between the corroded portion of the electroless nickel plating film and the electroless gold plating film, thereby reducing adhesion of the gold plating film to the electroless nickel plating film.
- the reducing agent is used to reduce the gold sulfite, which is the gold source, in order to precipitate gold.
- the reducing agent includes hydrazine compounds and ascorbic acid compounds in combination used at once.
- the hydrazine compounds are for facilitating the formation of the gold plating film on the nickel plating film or the palladium plating film, especially for facilitating the formation of the gold plating film on the palladium plating film in the ENEPIG process.
- hydrazine compounds examples include adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,1-dimethyhydrazine, 2-hydrazinobenzothiazole, acetohydrazide, 2-hydroxyethylhydrazine, ethoxycarbonylhydrazine, methoxycarbonylhydr
- the concentration of the hydrazine compound (which may be hydrazine compounds) in the plating bath may be in a range of 0.5 g/L to 15 g/L., preferably. If the concentration of the hydrazine is less than 0.5 g/L, a plating rate would become insufficient. Moreover, in general, the plating rate is increased proportionally to the concentration of the reducing agent. However, if the concentration of the hydrazine is greater than 15 g/L, the plating rate would not be improved so significantly regardless of the concentration, while bath stability of the plating bath would be deteriorated.
- the ascorbic acid compounds are for improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine compounds so as to facilitate the formation of the gold plating film, and the ascorbic acid compounds make it possible to form a gold plating film with a sufficient thickness (of 0.1 ⁇ m or thicker).
- ascorbic acid compounds examples include alkali metal salts such as ascorbic acid and sodium ascorbyl phosphate, alkali earth metal salts such as magnesium ascorbyl phosphate, esters such as ascorbic acid 2-glucoside, and the like. These ascorbic acid compounds may be used solely, or a combination of two or more thereof may be used.
- the concentration of the ascorbic acid compound (which may be ascorbic acid compounds) in the plating bath may be in a range of 1 g/L to 20 g/L, preferably. If the concentration of the ascorbic acid is less than 1 g/L, the plating rate would become insufficient, and if the concentration of the ascorbic acid is greater than 20 g/L, the plating rate would not be improved so significantly regardless of the concentration, while bath stability of the plating bath would be deteriorated.
- the electroless gold plating bath of the present disclosure is configured as follows:
- the reducing agent includes a combination of the hydrazine compounds and the ascorbic acid compounds used at once, the hydrazine compounds being capable of facilitating the formation of the gold plating film on the nickel plating film and the palladium plating film, and the hydrazine compounds being capable of facilitating the formation of the gold plating film by improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine compounds, thereby making it possible to form a uniform gold plating film (that is, uniform in outer appearance and excellent in the deposition property) with a sufficient thickness (of 0.1 ⁇ m or thicker) in one step process either in the ENIG process or ENEPIG process.
- An amine-based complexing agent is for improving the adhesion of the gold plating film to the electroless nickel plating film, and the electroless gold plating bath of the present disclosure includes an ethyleneamine as the amine-based complexing agent.
- ethyleneamine examples include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and the like. These polyethyleneamines may be used solely, or a combination of two or more thereof may be used.
- the concentration of the amine-based complexing agent in the plating bath may be in a range of 0.5 g/L to 10 g/L, preferably.
- the plating bath of the present disclosure may be configured such that the electroless gold plating bath further includes a known additive(s) of various kinds, if necessary.
- the additive include an anti-corrosion agent, an electric conducting salt, and the like.
- the anti-corrosion agent is an agent for preventing the corrosion on the surfaces of the nickel plating film and palladium plating film.
- the anti-corrosion agent is not particularly limited, but for example, the anti-corrosion agent may be 1,2,3-benzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-carboxamido-1,2,4-triazole, 3-aminopyrrolidine, 3-aminopyrazole, or the like.
- the concentration of the anti-corrosion agent in the plating bath may be in a range of 0.1 g/L to 2 g/L, preferably.
- examples of the electric conducting salt include sodium succinate, trisodium citrate, sodium malate, disodium malonate, sodium oxalate, disodium glutarate, sodium tartrate, and the like.
- the concentration of the electric conducting salt in the plating bath may be in a range of 5 g/L to 100 g/L, preferably.
- the formation of the gold plating film with the sufficient thickness (of 0.1 ⁇ m or thicker) on the surface of the nickel plating film and/or the palladium plating film would result in deterioration of the adhesion of the gold plating film to the electroless nickel plating film and/or corrosion on the surface of the electroless nickel plating film and/or the electroless palladium plating film.
- pH of the electroless gold plating bath of the present disclosure is in a range of 6 to 9. If the pH is less than 6, the plating rate would be insufficient, and if pH is greater than 9, the plating bath would be unstable.
- the pH of the plating bath can be adjusted by a pH adjuster such as sodium hydroxide, potassium hydroxide, ammonia water, tetramethyl ammonium hydroxide, sulfuric acid, hydrochloric acid, boric acid, phosphoric acid, monocarboxylic acid, or dicarboxylic acid.
- a pH adjuster such as sodium hydroxide, potassium hydroxide, ammonia water, tetramethyl ammonium hydroxide, sulfuric acid, hydrochloric acid, boric acid, phosphoric acid, monocarboxylic acid, or dicarboxylic acid.
- the temperature of the plating bath is not particularly limited, but may be in a range of 50°C to 80°C, preferably. If the temperature of the plating bath is less than 50°C, a deposition rate would be excessively slow, which would result in a long plating time, undesirably. If the temperature of the plating bath is higher than 80°C, the deposition rate would be excessively fast, which would produce coarse films, which would cause warping of a substrate due to thermal shrinkage of the films after the plating. Thus, such a high temperature of the plating bath is not preferable.
- the electroless gold plating bath of the present disclosure is applicable to any kinds of plating objects, and is applicable to plating objects which have been treated with known electroless gold plating processes (for example, wiring circuits, terminal portions, and the like of electronic parts such as printed wiring boards, ceramics substrates, semiconductor substrates, IC packages, and the like).
- the electroless gold plating bath according to the present disclosure is, for example, electroless gold plating process in the ENIG process and the ENEPIG process.
- an electroless gold plating film can be formed on a palladium plating film by implementing the electroless gold plating bath according to the present disclosure in such a way that a surface of a palladium plating film is subjected to the electroless gold plating process by immersing the palladium plating film in the electroless gold plating film.
- the temperature of the electroless gold plating process is adjusted to the bath temperature of the electroless gold plating bath described above.
- a process time of the electroless gold plating process is not particularly limited and may be adjusted as appropriate to attain a desired film thickness. More specifically, the electroless gold plating process may be, for example in a range of 30 sec to 15 hours, approximately.
- An electroless gold plating bath of Example 1 was prepared by mixing and stirring a gold sulfite (sodium gold sulfite), sodium succinate as the electric conducting salt, sodium thiosulfate and disodium sulfite as the complexing agent, 1,2,3-benzotriazole as the anti-corrosion agent, ethylenediamine as the amine-based complexing agent, and ascorbic acid and adipic dihydrazide as the reducing agent with concentrations listed in Table 1.
- the plating bath was set to a temperature (i.e., temperature of the plating processing) of 70°C, and the pH was set to 7.5.
- Step 1 A substrate (TEG wafer) was treated with a degreasing cleaning treatment (50°C, 300 sec) with a degreasing cleaner (EPITHAS MCL-16 (product name) available from C. Uyemura & Co., Ltd.).
- a degreasing cleaning treatment 50°C, 300 sec
- a degreasing cleaner EPITHAS MCL-16 (product name) available from C. Uyemura & Co., Ltd.
- Step 2 Next, the substrate was treated with a pickling treatment (21°C, 30 sec) with a nitric acid solution of 30 wt%, thereby forming an oxide film on the surface of the substrate.
- Step 3 Next, the substrate was treated with a primary zincate treatment (21°C, 20 sec) with a zincate treatment bath (with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.).
- a primary zincate treatment 21°C, 20 sec
- a zincate treatment bath with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.
- Step 4 The substrate was treated with a pickling treatment (21°C, 60 sec) with the nitric acid solution of 30 wt%, so as to peel off the zincate film and forming an oxide film on the surface of the substrate.
- Step 5 Next, the substrate was treated with a secondary zincate treatment (21°C, 40 sec) with a zincate treatment bath (with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.).
- a secondary zincate treatment 21°C, 40 sec
- a zincate treatment bath with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (a nickel plating film with a phosphorus concentration of 6% to 8% in the film and a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate thus treated with the electroless gold plating process was visually observed in terms of tonal change of the outer appearance of the substrate due to the gold deposition, so as to evaluate the deposition property of the gold plating film formed by the plating process.
- the evaluation found that the surface color of the substrate had been changed to yellow, confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NLL-1 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (a nickel plating film with a phosphorus concentration of 2% to 4% in the film and a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NLL-1 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-bismuth plating bath (with EPITHAS KSB-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-bismuth plating bath with EPITHAS KSB-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate was treated with an electroless plating process (56°C, 15 min) with a palladium plating bath (with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.3 ⁇ m) on the nickel plating film.
- a palladium plating bath with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the palladium plating film was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the plating object was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate thus prepared was treated with an electroless plating process (50°C, 15 min) with a palladium-phosphorus plating bath (with EPITHAS TFP-30 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.15 ⁇ m) on the nickel plating film.
- a palladium-phosphorus plating bath with EPITHAS TFP-30 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the palladium plating film was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate thus prepared was treated with an electroless plating process (78°C, 7 min) with a platinum plating bath (with EPITHAS TAE-30 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a platinum plating film (with a thickness of 0.2 ⁇ m) on the nickel plating film.
- a platinum plating bath with EPITHAS TAE-30 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the platinum plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (75°C, 60 min) with a cobalt-tungsten-phosphorus plating bath (with EPITHAS HWP-5 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a cobalt alloy plating film (with a thickness of 0.3 ⁇ m) on the substrate.
- a cobalt-tungsten-phosphorus plating bath with EPITHAS HWP-5 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the cobalt alloy plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the substrate thus prepared was treated with an electroless plating process (75°C, 60 min) with a cobalt-tungsten-boron plating bath (with EPITHAS HWB-31 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a cobalt alloy plating film (with a thickness of 0.5 ⁇ m) on the substrate.
- a cobalt-tungsten-boron plating bath with EPITHAS HWB-31 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the cobalt alloy plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- the substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- the electroless gold plating bath according to the present disclosure As described above, it was confirmed that gold was successfully deposited by the use of the electroless gold plating bath according to the present disclosure in any of the cases where the base plating film was the electroless nickel-phosphorus plating film, the electroless nickel-bismuth plating film, the electroless palladium plating film, the electroless palladium-phosphorus plating film, the electroless platinum plating film, or the electroless cobalt alloy plating film, thereby confirming that the electroless gold plating bath according to the present disclosure could work usefully.
- Electroless gold plating baths of Examples 1 to 48 and Comparative Examples 1 to 9 were prepared by mixing and stirring a gold sulfite (sodium gold sulfite), sodium succinate as the electric conducting salt, sodium thiosulfate and disodium sulfite as the complexing agent, 1,2,3-benzotriazole as the anti-corrosion agent, an amine-based complexing agent, and ascorbic acid compounds and hydrazine compounds as the reducing agent with concentrations listed in Tables 2 to 6.
- the plating bath was set to a temperature (i.e., temperature of the plating processing) in a range of 50°C to 80°C, and the pH was set in a range of 6 to 9.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath of one of Examples 1 to 48 and Comparative Examples 1 to 9, thereby forming an electroless gold plating film on the nickel plating film.
- the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 ⁇ m) on the substrate.
- a nickel-phosphorus plating bath with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.
- the substrate was treated with an electroless plating process (56°C, 15 min) with a palladium plating bath (with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.3 ⁇ m) on the nickel plating film.
- a palladium plating bath with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.
- the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath of one of Examples 1 to 48 and Comparative Examples 1 to 9, thereby forming an electroless gold plating film on the palladium plating film.
- a sample of the electroless gold plating film with a size of 2.5 cm ⁇ 2.5 cm was prepared.
- An adhesive cellophane tape with a width of approximately 2 cm was adhered to a surface of the electroless gold plating film and manually peeled off from the surface. If the electroless gold plating film was not peeled off together with the tape, the electroless gold plating film was evaluated as good, and if peeled off, the electroless gold plating film was evaluated as poor.
- the results of the evaluation are presented in Tables 2 to 6.
- the surfaces of the electroless gold plating film were observed with a scanning electron microscope (SEM, available from JEOL Ltd.) to evaluate in such a way that films with uniform gold plating deposition were evaluated as good, and films with non-uniform gold plating deposition, in which gold deposition was partially unsuccessful, were evaluated as poor.
- SEM scanning electron microscope
- the electroless gold plating film was peeled off, and a base film of the electroless gold plating film (the surface of the electroless nickel plating film in the case of the ENIG process and the electroless nickel plating film under the electroless palladium plating film in the case of ENEPIG process) was observed by a scanning electron microscope, and a cross-section thereof was observed with a focused ion beam (FIB) device (available from Hitachi High-Tech Corporation), evaluating as poor if the electroless nickel plating film has corrosion on the surface or the cross-section thereof (that is, if the electroless nickel plating film has a hole on the surface or a hole or staining on the cross-section) and evaluating as good if the electroless nickel plating film had no such corrosion.
- the results of the evaluation are presented in Tables 2 to 6.
- the electroless gold plating baths of Examples 1 to 48 including a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, wherein a combination of the hydrazine compounds and the ascorbic acid serve as a reducing agent, make it possible to form a uniform gold plating film (that is, uniform in outer appearance and excellent in the deposition property) with a sufficient thickness (of 0.1 ⁇ m or thicker) by a single-step process either in the ENIG process or ENEPIG process, because the hydrazine compounds capable of facilitating the formation of the gold plating film on the nickel plating film or the palladium plating film and the ascorbic acid compounds capable of facilitating the formation of the gold plating film by improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine are used at once.
- Comparative Example 1 without hydrazine compounds was poor in the outer appearance and deposition property, and the gold plating film thereof was not uniform, as understood from Table 6.
- Comparative Example 2 without ascorbic acid compounds was poor in the deposition property, and the gold plating film thereof was not uniform.
- Comparative Example 3 without a sodium thiosulfate was unstable in gold solubility in the electroless gold plating bath and poor in the outer appearance and deposition property, and the gold plating film thereof was not uniform.
- Comparative Example 6 without ethylene diamine was poor in the adhesion of the gold plating film to the electroless nickel plating film.
- Comparative Example 8 without an anti-corrosion agent was poor in the adhesion of the gold plating film to the electroless nickel plating film, because local corrosions increased on the electroless nickel plating film, causing gaps between the corroded portion of the electroless nickel plating film and the electroless gold plating film.
- the electroless gold plating bath according to the present disclosure is suitably applicable especially to formation of an electroless gold plating film in the ENIG process and the ENEPIG process.
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Abstract
An electroless gold plating bath is presented, which is capable of forming a uniform gold plating film with a sufficient thickness in one step in both the ENIG process and the ENEPIG process.The electroless gold plating bath includes a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, and isopropylhydrazine hydrochloride.
Description
- The present disclosure relates to an electroless gold plating bath.
- Gold has high electrical conductivity next to silver and copper, and is excellent in physical properties such as connectivity in thermocompression bonding, and is also excellent in chemical properties such as oxidation resistance and chemical resistance. Therefore, gold plating with gold is widely used as a final surface treatment method for circuits on printed wiring boards, mounting portions and terminal portions of IC packages, and the like in the field of the electronics industry. In recent years, along with the improvement of electronic components to be smaller and denser, electroless plating methods attaining excellent functionality without the need of lead wiring have been used preferably.
- One example of such an electroless plating method thus used is an Electroless Nickel Immersion Gold (ENIG) process. By using the ENIG process, a plating film sequentially including an electroless nickel plating film and a substitution gold plating film can be obtained. Moreover, for example, an Electroless Nickel Electroless Palladium Immersion Gold (ENEPIG) process has been also used as such an electroless plating method. By using the ENEPIG process, a plating film sequentially including an electroless nickel plating film, an electroless palladium plating film, and a substitution gold plating film can be obtained.
- As a reduction substitution type electroless gold plating bath used in these electroless plating methods, for example, an electroless gold plating bath has been proposed, which contains a water-soluble gold compound, a complexing agent, and a reducing agent as well as polyvinyl alcohol and/or polyvinylpyrrolidone added as a stabilizer. It is described that such a configuration makes it possible to form a good gold plating film only in metal portions and is preferably applicable to gold plating for ceramics IC, packages, and the like (For example, see
Japanese Patent No.2927142 - In the known electroless gold plating bath described above, it is difficult to deposit gold on the palladium plating film, so that formation of the gold plating film would be insufficient in minute portions such as terminal portions, thereby leading to difficulty in forming a uniform gold plating film.
- Moreover, in order to form a gold plating film with a sufficient thickness (thickness of 0.1 µm or thicker) on the nickel plating film, there has arisen the following problem: It is necessary to form the electroless gold plating film with the electroless gold plating bath after the formation of the substitution gold plating film on a plating object, so that the gold plating needs to be performed in two steps.
- In view of the problems described above, an object of the present disclosure is to provide an electroless gold plating bath, which is capable of forming a uniform gold plating film with a sufficient thickness in one step in both the ENIG process and the ENEPIG process.
- In order to attain the object, the electroless gold plating bath of the present disclosure includes a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,1-dimethyhydrazine, 2-hydrazinobenzothiazole, acetohydrazide, 2-hydroxyethylhydrazine, ethoxycarbonylhydrazine, methoxycarbonylhydrazine, phenylhydrazine-4-sulfonic acid, and benzohydrazide.
- According to the present disclosure, it becomes possible to provide an electroless gold plating bath, which is capable of forming a uniform gold plating film with a sufficient thickness in one step in both the ENIG process and the ENEPIG process.
- In the following, an electroless gold plating bath of the present disclosure will be described.
- The electroless gold plating bath of the present disclosure is an electroless gold plating bath including a gold sulfite as a gold source, a thiosulfate as a complexing agent, ascorbic acid compounds as a reducing agent, and hydrazine compounds as a reducing agent.
- The electroless gold plating bath of the present disclosure is a cyanide-free bath (non-cyanide bath), and includes, as the gold source, gold sulfite (e.g., sodium gold sulfite), which is a water-soluble gold compound with no cyano group.
- The concentration of the gold sulfite in the plating bath may be preferably 0.5 g/L to 2 g/L based on gold. A concentration of the gold sulfite of less than 0.5 g/L would result in a low plating deposition rate, while a concentration of the gold sulfite of more than 2 g/L would result in a poor adhesion of the gold plating film to the electroless nickel plating film.
- The complexing agent is used to stabilize the solubility of gold in the electroless gold plating bath. The electroless gold plating bath of the present disclosure includes a sulfur compound as the complexing agent. The sulfur compound may be a thiosulfate (such as sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, or the like) a sulfite (such as sodium sulfite, potassium sulfite, ammonium sulfite, or the like). These complexing agents may be used solely, or a combination of two or more thereof may be used.
- Moreover, the concentration of the thiosulfate (which may be thiosulfates) in the plating bath may be in a range of 0.5 g/L to 10 g/L, preferably. If the concentration of the thiosulfate is less than 0.5 g/L. the effect of the complexing agent would be insufficient, and if the concentration of the thiosulfate is greater than 10 g/L, local corrosion of the electroless nickel plating film would be increased, which would cause a gap between the corroded portion of the electroless nickel plating film and the electroless gold plating film, thereby reducing adhesion of the gold plating film to the electroless nickel plating film.
- From the viewpoint of suppressing the decrease in adhesion of the gold plating film to the electroless nickel plating film and suppressing the corrosion on the surfaces of the electroless nickel plating film and electroless palladium plating film, it is preferable that a mass ratio of gold in the gold sulfite to thiosulfate be gold: thiosulfate = 1: 0.5 to 1: 10.
- The reducing agent is used to reduce the gold sulfite, which is the gold source, in order to precipitate gold. In the electroless gold plating bath of the present disclosure, the reducing agent includes hydrazine compounds and ascorbic acid compounds in combination used at once.
- The hydrazine compounds are for facilitating the formation of the gold plating film on the nickel plating film or the palladium plating film, especially for facilitating the formation of the gold plating film on the palladium plating film in the ENEPIG process.
- Examples of the hydrazine compounds include adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,1-dimethyhydrazine, 2-hydrazinobenzothiazole, acetohydrazide, 2-hydroxyethylhydrazine, ethoxycarbonylhydrazine, methoxycarbonylhydrazine, phenylhydrazine-4-sulfonic acid, benzohydrazide, and the like. These hydrazine compounds may be used solely, or a combination of two or more thereof may be used.
- Moreover, the concentration of the hydrazine compound (which may be hydrazine compounds) in the plating bath may be in a range of 0.5 g/L to 15 g/L., preferably. If the concentration of the hydrazine is less than 0.5 g/L, a plating rate would become insufficient. Moreover, in general, the plating rate is increased proportionally to the concentration of the reducing agent. However, if the concentration of the hydrazine is greater than 15 g/L, the plating rate would not be improved so significantly regardless of the concentration, while bath stability of the plating bath would be deteriorated.
- The ascorbic acid compounds are for improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine compounds so as to facilitate the formation of the gold plating film, and the ascorbic acid compounds make it possible to form a gold plating film with a sufficient thickness (of 0.1 µm or thicker).
- Examples of the ascorbic acid compounds include alkali metal salts such as ascorbic acid and sodium ascorbyl phosphate, alkali earth metal salts such as magnesium ascorbyl phosphate, esters such as ascorbic acid 2-glucoside, and the like. These ascorbic acid compounds may be used solely, or a combination of two or more thereof may be used.
- Moreover, the concentration of the ascorbic acid compound (which may be ascorbic acid compounds) in the plating bath may be in a range of 1 g/L to 20 g/L, preferably. If the concentration of the ascorbic acid is less than 1 g/L, the plating rate would become insufficient, and if the concentration of the ascorbic acid is greater than 20 g/L, the plating rate would not be improved so significantly regardless of the concentration, while bath stability of the plating bath would be deteriorated.
- The electroless gold plating bath of the present disclosure is configured as follows: The reducing agent includes a combination of the hydrazine compounds and the ascorbic acid compounds used at once, the hydrazine compounds being capable of facilitating the formation of the gold plating film on the nickel plating film and the palladium plating film, and the hydrazine compounds being capable of facilitating the formation of the gold plating film by improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine compounds, thereby making it possible to form a uniform gold plating film (that is, uniform in outer appearance and excellent in the deposition property) with a sufficient thickness (of 0.1 µm or thicker) in one step process either in the ENIG process or ENEPIG process.
- An amine-based complexing agent is for improving the adhesion of the gold plating film to the electroless nickel plating film, and the electroless gold plating bath of the present disclosure includes an ethyleneamine as the amine-based complexing agent.
- Examples of the ethyleneamine include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and the like. These polyethyleneamines may be used solely, or a combination of two or more thereof may be used.
- Moreover, the concentration of the amine-based complexing agent in the plating bath may be in a range of 0.5 g/L to 10 g/L, preferably.
- The plating bath of the present disclosure may be configured such that the electroless gold plating bath further includes a known additive(s) of various kinds, if necessary. Examples of the additive include an anti-corrosion agent, an electric conducting salt, and the like.
- More specifically, the anti-corrosion agent is an agent for preventing the corrosion on the surfaces of the nickel plating film and palladium plating film. In the electroless gold plating bath of the present disclosure, the anti-corrosion agent is not particularly limited, but for example, the anti-corrosion agent may be 1,2,3-benzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-carboxamido-1,2,4-triazole, 3-aminopyrrolidine, 3-aminopyrazole, or the like.
- Moreover, the concentration of the anti-corrosion agent in the plating bath may be in a range of 0.1 g/L to 2 g/L, preferably.
- Moreover, examples of the electric conducting salt include sodium succinate, trisodium citrate, sodium malate, disodium malonate, sodium oxalate, disodium glutarate, sodium tartrate, and the like.
- Moreover, the concentration of the electric conducting salt in the plating bath may be in a range of 5 g/L to 100 g/L, preferably.
- Moreover, the formation of the gold plating film with the sufficient thickness (of 0.1 µm or thicker) on the surface of the nickel plating film and/or the palladium plating film would result in deterioration of the adhesion of the gold plating film to the electroless nickel plating film and/or corrosion on the surface of the electroless nickel plating film and/or the electroless palladium plating film. Therefore, in order to suppress the deterioration of the adhesion of the gold plating film to the electroless nickel plating film and to suppress the corrosion on the surface of the electroless nickel plating film and/or the electroless palladium plating film, it is preferable that a mass ratio between the anti-corrosion agent and the amine-based complexing agent be anti-corrosion agent: amine-based complexing agent = 1: 0.5 to 1: 10.
- It is preferable that pH of the electroless gold plating bath of the present disclosure is in a range of 6 to 9. If the pH is less than 6, the plating rate would be insufficient, and if pH is greater than 9, the plating bath would be unstable.
- The pH of the plating bath can be adjusted by a pH adjuster such as sodium hydroxide, potassium hydroxide, ammonia water, tetramethyl ammonium hydroxide, sulfuric acid, hydrochloric acid, boric acid, phosphoric acid, monocarboxylic acid, or dicarboxylic acid.
- The temperature of the plating bath is not particularly limited, but may be in a range of 50°C to 80°C, preferably. If the temperature of the plating bath is less than 50°C, a deposition rate would be excessively slow, which would result in a long plating time, undesirably. If the temperature of the plating bath is higher than 80°C, the deposition rate would be excessively fast, which would produce coarse films, which would cause warping of a substrate due to thermal shrinkage of the films after the plating. Thus, such a high temperature of the plating bath is not preferable.
- The electroless gold plating bath of the present disclosure is applicable to any kinds of plating objects, and is applicable to plating objects which have been treated with known electroless gold plating processes (for example, wiring circuits, terminal portions, and the like of electronic parts such as printed wiring boards, ceramics substrates, semiconductor substrates, IC packages, and the like).
- The electroless gold plating bath according to the present disclosure is, for example, electroless gold plating process in the ENIG process and the ENEPIG process. For example, an electroless gold plating film can be formed on a palladium plating film by implementing the electroless gold plating bath according to the present disclosure in such a way that a surface of a palladium plating film is subjected to the electroless gold plating process by immersing the palladium plating film in the electroless gold plating film. The temperature of the electroless gold plating process is adjusted to the bath temperature of the electroless gold plating bath described above.
- Moreover, a process time of the electroless gold plating process is not particularly limited and may be adjusted as appropriate to attain a desired film thickness. More specifically, the electroless gold plating process may be, for example in a range of 30 sec to 15 hours, approximately.
- The following describes the present disclosure more specifically based on Examples and Comparative Examples. However, the present invention is not limited to the following Examples.
- First, to confirm that the electroless gold plating bath according to the present disclosure works usefully, the deposition property of gold plating films formed by plating process using the electroless gold plating bath according to the present disclosure was evaluated.
- An electroless gold plating bath of Example 1 was prepared by mixing and stirring a gold sulfite (sodium gold sulfite), sodium succinate as the electric conducting salt, sodium thiosulfate and disodium sulfite as the complexing agent, 1,2,3-benzotriazole as the anti-corrosion agent, ethylenediamine as the amine-based complexing agent, and ascorbic acid and adipic dihydrazide as the reducing agent with concentrations listed in Table 1. The plating bath was set to a temperature (i.e., temperature of the plating processing) of 70°C, and the pH was set to 7.5.
[Table 1] Composition of Plating Bath Example 1 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 Electric Conducting Salt Sodium Succinate g/L 30 Complexing Agent Sodium Thiosulfate g/L 1 Disodium Sulfite g/L 30 Anti-Corrosion Agent 1,2,3-Benzotriazole g/L 1 Amine-based Complexing Agent Ethylenediamine g/L 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 Reducing Agent (Hydrazine Compounds) Adipic Dihydrazide g/L 5 Process Temperature (°C) 70 pH 7.5 - A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the following pretreatment steps 1 to 5 in this order.
- Step 1: A substrate (TEG wafer) was treated with a degreasing cleaning treatment (50°C, 300 sec) with a degreasing cleaner (EPITHAS MCL-16 (product name) available from C. Uyemura & Co., Ltd.).
- Step 2: Next, the substrate was treated with a pickling treatment (21°C, 30 sec) with a nitric acid solution of 30 wt%, thereby forming an oxide film on the surface of the substrate.
- Step 3: Next, the substrate was treated with a primary zincate treatment (21°C, 20 sec) with a zincate treatment bath (with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.).
- Step 4: The substrate was treated with a pickling treatment (21°C, 60 sec) with the nitric acid solution of 30 wt%, so as to peel off the zincate film and forming an oxide film on the surface of the substrate.
- Step 5: Next, the substrate was treated with a secondary zincate treatment (21°C, 40 sec) with a zincate treatment bath (with EPITHAS MCT-51 (product name) available from C. Uyemura & Co., Ltd.).
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (a nickel plating film with a phosphorus concentration of 6% to 8% in the film and a thickness of 3 µm) on the substrate.
- Next, the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate thus treated with the electroless gold plating process was visually observed in terms of tonal change of the outer appearance of the substrate due to the gold deposition, so as to evaluate the deposition property of the gold plating film formed by the plating process. The evaluation found that the surface color of the substrate had been changed to yellow, confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NLL-1 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (a nickel plating film with a phosphorus concentration of 2% to 4% in the film and a thickness of 3 µm) on the substrate.
- Next, the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-bismuth plating bath (with EPITHAS KSB-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate was treated with an electroless plating process (56°C, 15 min) with a palladium plating bath (with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.3 µm) on the nickel plating film.
- Next, the substrate with the palladium plating film was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The plating object was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate thus prepared was treated with an electroless plating process (50°C, 15 min) with a palladium-phosphorus plating bath (with EPITHAS TFP-30 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.15 µm) on the nickel plating film.
- Next, the substrate with the palladium plating film was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate thus prepared was treated with an electroless plating process (78°C, 7 min) with a platinum plating bath (with EPITHAS TAE-30 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a platinum plating film (with a thickness of 0.2 µm) on the nickel plating film.
- Next, the substrate with the platinum plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (75°C, 60 min) with a cobalt-tungsten-phosphorus plating bath (with EPITHAS HWP-5 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a cobalt alloy plating film (with a thickness of 0.3 µm) on the substrate.
- Next, the substrate with the cobalt alloy plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (75°C, 60 min) with a cobalt-tungsten-boron plating bath (with EPITHAS HWB-31 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a cobalt alloy plating film (with a thickness of 0.5 µm) on the substrate.
- Next, the substrate with the cobalt alloy plating film thereon was immersed for 15 min in the plating bath prepared as above, thereby forming an electroless gold plating film on the plating object.
- The substrate was evaluated in terms of the deposition property of the plating, finding a surface color change of the substrate to yellow and thereby confirming gold deposition.
- As described above, it was confirmed that gold was successfully deposited by the use of the electroless gold plating bath according to the present disclosure in any of the cases where the base plating film was the electroless nickel-phosphorus plating film, the electroless nickel-bismuth plating film, the electroless palladium plating film, the electroless palladium-phosphorus plating film, the electroless platinum plating film, or the electroless cobalt alloy plating film, thereby confirming that the electroless gold plating bath according to the present disclosure could work usefully.
- Next, properties of gold plating films formed by the plating process with the electroless gold plating bath in the ENIG Process and ENEPIG process were evaluated.
- Electroless gold plating baths of Examples 1 to 48 and Comparative Examples 1 to 9 were prepared by mixing and stirring a gold sulfite (sodium gold sulfite), sodium succinate as the electric conducting salt, sodium thiosulfate and disodium sulfite as the complexing agent, 1,2,3-benzotriazole as the anti-corrosion agent, an amine-based complexing agent, and ascorbic acid compounds and hydrazine compounds as the reducing agent with concentrations listed in Tables 2 to 6. The plating bath was set to a temperature (i.e., temperature of the plating processing) in a range of 50°C to 80°C, and the pH was set in a range of 6 to 9.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath of one of Examples 1 to 48 and Comparative Examples 1 to 9, thereby forming an electroless gold plating film on the nickel plating film.
- A TEG wafer with electrodes made from an aluminum-copper alloy, which is an aluminum alloy, was provided and the electrodes were treated with the aforementioned pretreatment steps 1 to 5 in this order.
- Next, the substrate thus prepared was treated with an electroless plating process (80°C, 15 min) with a nickel-phosphorus plating bath (with EPITHAS NPR-18 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a nickel plating film (with a thickness of 3 µm) on the substrate.
- Next, the substrate was treated with an electroless plating process (56°C, 15 min) with a palladium plating bath (with EPITHAS TFP-25 (product name) available from C. Uyemura & Co., Ltd.), thereby forming a palladium plating film (with a thickness of 0.3 µm) on the nickel plating film.
- Next, the substrate with the nickel plating film thereon was immersed for 15 min in the plating bath of one of Examples 1 to 48 and Comparative Examples 1 to 9, thereby forming an electroless gold plating film on the palladium plating film.
- The surfaces of the electroless gold plating film were visually observed to evaluate in such a way that films with uniform gold color outer appearance were evaluated as good, and films with color changes to red instead of gold were evaluated as poor. The results of the evaluation are presented in Tables 2 to 6.
- A sample of the electroless gold plating film with a size of 2.5 cm × 2.5 cm was prepared. An adhesive cellophane tape with a width of approximately 2 cm was adhered to a surface of the electroless gold plating film and manually peeled off from the surface. If the electroless gold plating film was not peeled off together with the tape, the electroless gold plating film was evaluated as good, and if peeled off, the electroless gold plating film was evaluated as poor. The results of the evaluation are presented in Tables 2 to 6.
- The surfaces of the electroless gold plating film were observed with a scanning electron microscope (SEM, available from JEOL Ltd.) to evaluate in such a way that films with uniform gold plating deposition were evaluated as good, and films with non-uniform gold plating deposition, in which gold deposition was partially unsuccessful, were evaluated as poor. The results of the evaluation are presented in Tables 2 to 6.
- By using COPKIARIP AU-1 (available from C. Uyemura & Co., Ltd.), the electroless gold plating film was peeled off, and a base film of the electroless gold plating film (the surface of the electroless nickel plating film in the case of the ENIG process and the electroless nickel plating film under the electroless palladium plating film in the case of ENEPIG process) was observed by a scanning electron microscope, and a cross-section thereof was observed with a focused ion beam (FIB) device (available from Hitachi High-Tech Corporation), evaluating as poor if the electroless nickel plating film has corrosion on the surface or the cross-section thereof (that is, if the electroless nickel plating film has a hole on the surface or a hole or staining on the cross-section) and evaluating as good if the electroless nickel plating film had no such corrosion. The results of the evaluation are presented in Tables 2 to 6.
- Next, the thicknesses of the electroless gold plating films were measured by using an X-ray fluorescence thickness meter available from FISCHER INSTRUMENTS K.K. The results of the evaluation are presented in Tables 2 to 6.
[Table 2] Compositions of Plating Baths Examples 1 2 3 4 5 6 7 8 9 10 11 12 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 1 1 1 1 1 1 1 1 1 1 1 Electric Conducting Salt Sodium Succinate g/L 30 30 30 30 30 30 30 30 30 30 30 30 Complexing Agent Sodium Thiosulfate g/L 1 1 1 1 1 1 1 1 1 1 1 1 Disodium Sulfite g/L 30 30 30 30 30 30 30 30 30 30 30 30 Anti-Corrosion Agent 1.2.3 -Benzotriazole g/L 1 1 1 1 1 1 1 1 1 1 1 1 Amine-based Complexing Ethylenediamine g/L 1 1 1 1 1 1 1 1 1 1 1 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 5 5 20 1 5 5 5 5 Ascorbic Acid 2-Glucoside g/L 5 Magnesium Ascorbyl Phosphate g/L 5 Sodium Ascorbyl Phosphate g/L 5 Reducing Agent (Hydrazine Compounds) Adipic Dihydrazide g/L 5 15 0.5 5 5 5 5 5 Propionic Hydrazide g/L 5 Hvdrazine Sulfate g/L 5 Hvdrazine Monohvdrochloride g/L 5 Hvdrazine Dihvdrochloride g/L 5 Hvdrazine Carbonate g/L Gold: Sodium Thiosulfate 1:1 Anti-Corrosion Agent: Amine-based Complexing Agent 1:1 Process Temperature (°C) 70 pH 7.5 ENIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 ENEPIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 [Table 3] Compositions of Plating Baths Examples 13 14 15 16 17 18 19 20 21 22 23 24 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 1 1 1 1 1 1 1 1 1 1 1 Electric Conducting Salt Sodium Succinate g/L 30 30 30 30 30 30 30 30 30 30 30 30 Complexing Agent Sodium Thiosulfate g/L 1 1 1 1 1 1 1 1 1 1 1 1 Disodium Sulfite g/L 30 30 30 30 30 30 30 30 30 30 30 30 Anti-Corrosion Agent 1,2,3 -Benzotriazole g/L 1 1 1 1 1 1 1 1 1 1 1 1 Amine-based Complexing Agent Ethylenediamine g/L 1 1 1 1 1 1 1 1 1 1 1 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 5 5 5 5 5 5 5 5 5 5 5 Reducing Agent (Hydrazine Compounds) Hydrazine Carbonate g/L 5 Hydrazine Monohydrate g/L 5 Sebacic Dihydrazide g/L 5 Dodecanediohydrazide g/L 5 Isophthalic Dihydrazide g/L 5 Salicylic Hydrazide g/L 5 3-Hydro-2-Naphthoic Hydrazide, g/L 5 Benzophenone Hydrazone g/L 5 Phenylhydrazine g/L 5 Benzylhydrazine Monohydrochloride g/L 5 Methylhydrazine Sulfate g/L 5 Isopropylhydrazine Hydrochloride g/L 5 Gold: Sodium Thiosulfate 1:1 Anti-Corrosion Agent: Amine-based Complexing Agent 1:1 Process Temperature (°C) 70 pH 7.5 ENIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 ENEPIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 [Table 4] Compositions of Plating Baths Examples 25 26 27 28 29 30 31 32 33 34 35 36 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 1 1 1 1 1 1 1 1 1 0.5 2 Electric Conducting Salt Sodium Succinate g/L 30 30 30 30 30 30 30 30 30 30 30 30 Complexing Agent Sodium Thiosulfate g/L 1 1 1 1 1 1 1 1 0.5 10 1 1 Disodium Sulfite g/L 30 30 30 30 30 30 30 30 30 30 30 30 Anti-Corrosion Agent 1,2,3 -Benzotriazole g/L 1 1 1 1 1 1 1 1 1 1 1 1 Amine-based Complexing Ethylenediamine g/L 1 1 1 1 1 1 1 1 1 1 1 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 5 5 5 5 5 5 5 5 5 5 5 Reducing Agent (Hydrazine Compounds) Adipic Dihydrazide g/L 5 5 5 5 1,1-Dimethylhydrazine g/L 5 2-Hydrazinobenzothiazole g/L 5 Acetohydrazide g/L 5 2-Hydroxyethylhydrazine g/L 5 Ethoxycarbonylhydrazine g/L 5 Methoxycarbonylhydrazine g/L 5 Phenylhydrazine-4-Sulfonic acid g/L 5 Benzohydrazide g/L 5 Gold: Sodium Thiosulfate 1:1 1:1 1:1 1:1 1:1 1:1 1:1 1:1 2:1 1:10 1:2 2:1 Anti-Corrosion Agent: Amine-based Complexing Agent 1:01 Process Temperature (°C) 70 pH 7.5 ENIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 ENEPIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 [Table 5] Compositions of Plating Baths Examples 37 38 39 40 41 42 43 44 45 46 47 48 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 1 1 1 1 1 1 1 1 1 1 1 Electric Conducting Salt Sodium Succinate g/L 30 30 30 30 30 30 30 30 30 30 30 30 Complexing Agent Sodium Thiosulfate g/L 1 1 1 1 1 1 1 1 1 1 1 1 Disodium Sulfite g/L 30 30 30 30 30 30 30 30 30 30 30 30 Anti-Corrosion Agent 1,2,3 -Benzotriazole g/L 1 1 1 1 1 1 0.1 2 1 1 1 1 Amine-based Complexing Agent Ethylenediamine g/L 0.5 10 1 1 1 1 1 1 Diethylenetriamine g/L 1 Triethylenetetramine g/L 1 Tetraethylenepentamine g/L 1 Pentaethylenehexamine g/L 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 5 5 5 5 5 5 5 5 5 5 5 Reducing Agent (Hydrazine Compounds) Adipic Dihydrazide g/L 5 5 5 5 5 5 5 5 5 5 5 5 Gold: Sodium Thiosulfate 1:1 Anti-Corrosion Agent: Amine-based Complexing Agent 1:1 1:1 1:1 1:1 2:1 1:10 1:10 2:1 1:1 1:1 1:1 1:1 Process Temperature (°C) 70 70 70 70 70 70 70 70 70 70 50 80 pH 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 6 9 7.5 7.5 ENIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 ENEPIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Good Good Good Good Good Good Good Good Good Good Good Good Deposition Property Good Good Good Good Good Good Good Good Good Good Good Good No Corrosion Good Good Good Good Good Good Good Good Good Good Good Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 [Table 6] Compositions of Plating Baths Comparative Examples 1 2 3 4 5 6 7 8 9 Gold Sulfite Sodium Gold Sulfite (as Au) g/L 1 1 1 1 5 1 1 1 1 Electric Conducting Salt Sodium Succinate g/L 30 30 30 30 30 30 30 30 30 Complexing Agent Sodium Thiosulfate g/L 1 1 15 1 1 1 1 1 Disodium Sulfite g/L 30 30 30 30 30 30 30 30 30 Anti-Corrosion Agent 1,2,3 -Benzotriazole g/L 1 1 1 1 1 1 1 3 Amine-based Complexing Agent Ethylenediamine g/L 1 1 1 1 1 15 1 1 Reducing Agent (Ascorbic Acid Compounds) Ascorbic Acid g/L 5 5 5 5 5 5 5 5 Reducing Agent (Hydrazine Compounds) Adipic Dihydrazide g/L 5 5 5 5 5 5 5 5 Gold: Sodium Thiosulfate 1:1 1:1 - 1:15 5:1 1:1 1:1 1:1 1:1 Anti-Corrosion Agent: Amine-based Complexing Agent 1:1 1:1 1:1 1:1 1:1 - 1:15 - 3:1 Process Temperature (°C) 70 70 70 70 70 70 70 70 70 pH 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 ENIG Process Uniform Outer Appearance Good Good Good Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Poor Poor Poor Poor Poor Poor Deposition Property Poor Poor Poor Good Good Good Good Good Good No Corrosion Good Good Good Poor Good Good Poor Poor Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.03 0.03 0.1 0.1 0.1 0.1 0.1 0.1 ENEPIG Process Uniform Outer Appearance Poor Good Poor Good Good Good Good Good Good No Peeling-Off of Electroless Gold Plating Film Good Good Good Good Good Good Good Good Good Deposition Property Poor Poor Poor Good Good Good Good Good Good No Corrosion Good Good Good Poor Good Good Poor Poor Good Film Thickness of Electroless Gold Plating Film (µm) 0.1 0.03 0.03 0.1 0.1 0.1 0.1 0.1 0.1 - As demonstrated in Tables 2 to 5, the electroless gold plating baths of Examples 1 to 48, including a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds, wherein a combination of the hydrazine compounds and the ascorbic acid serve as a reducing agent, make it possible to form a uniform gold plating film (that is, uniform in outer appearance and excellent in the deposition property) with a sufficient thickness (of 0.1 µm or thicker) by a single-step process either in the ENIG process or ENEPIG process, because the hydrazine compounds capable of facilitating the formation of the gold plating film on the nickel plating film or the palladium plating film and the ascorbic acid compounds capable of facilitating the formation of the gold plating film by improving the deposition property of the gold plating on the gold plating film deposited by the hydrazine are used at once.
- On the other hand, the Comparative Example 1 without hydrazine compounds was poor in the outer appearance and deposition property, and the gold plating film thereof was not uniform, as understood from Table 6.
- Moreover, the Comparative Example 2 without ascorbic acid compounds was poor in the deposition property, and the gold plating film thereof was not uniform.
- Moreover, the Comparative Example 3 without a sodium thiosulfate was unstable in gold solubility in the electroless gold plating bath and poor in the outer appearance and deposition property, and the gold plating film thereof was not uniform.
- Moreover, the Comparative Example 4, in which the mass ratio of the gold in the gold sulfite to the sodium thiosulfate was 1: 15 out of the range of gold: sodium thiosulfate = 1: 0.5 to 1: 10, was poor in the adhesion of the gold plating film to the electroless nickel plating film and corrosion occurred on the surface of the electroless nickel plating film.
- Moreover, the Comparative Example 5, in which the mass ratio of the gold in the gold sulfite to the sodium thiosulfate was 5: 1 out of the range of gold: sodium thiosulfate = 1: 0.5 to 1: 10, was poor in the adhesion of the gold plating film to the electroless nickel plating film.
- Moreover, the Comparative Example 6 without ethylene diamine was poor in the adhesion of the gold plating film to the electroless nickel plating film.
- Moreover, the Comparative Example 7, in which the mass ratio of the anti-corrosion agent to amine-based complexing agent was 1: 15 out of the range of anti-corrosion agent: amine-based complexing agent = 1: 0.5 to 1: 10, was poor in the adhesion of the gold plating film to the electroless nickel plating film and corrosion occurred on the surface of the electroless nickel plating film.
- Moreover, the Comparative Example 8 without an anti-corrosion agent was poor in the adhesion of the gold plating film to the electroless nickel plating film, because local corrosions increased on the electroless nickel plating film, causing gaps between the corroded portion of the electroless nickel plating film and the electroless gold plating film.
- Moreover, the Comparative Example 9, in which the mass ratio of the anti-corrosion agent to the amine-based complexing agent was 3: 1 out of the range of anti-corrosion agent: amine-based complexing agent = 1: 0.5 to 1: 10, was poor in the adhesion of the gold plating film to the electroless nickel plating film.
- The electroless gold plating bath according to the present disclosure is suitably applicable especially to formation of an electroless gold plating film in the ENIG process and the ENEPIG process.
Claims (5)
- An electroless gold plating bath, comprising a gold sulfite, a thiosulfate, ascorbic acid compounds, and hydrazine compounds,
the hydrazine compounds being at least one selected from the group consisting of adipic dihydrazide, propionic hydrazide, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine carbonate, hydrazine monohydrate, sebacic dihydrazide, dodecanediohydrazide, isophthalic dihydrazide, salicylic hydrazide, 3-hydro-2-naphthoic hydrazide, benzophenone hydrazone, phenylhydrazine, benzylhydrazine monohydrochloride, methylhydrazine sulfate, isopropylhydrazine hydrochloride, 1,1-dimethyhydrazine, 2-hydrazinobenzothiazole, acetohydrazide, 2-hydroxyethylhydrazine, ethoxycarbonylhydrazine, methoxycarbonylhydrazine, phenylhydrazine-4-sulfonic acid, and benzohydrazide. - The electroless gold plating bath of claim 1, wherein
the ascorbic acid compounds are at least one selected from the group consisting of ascorbic acid, sodium ascorbyl phosphate, magnesium ascorbyl phosphate, and ascorbic acid 2-glucoside. - The electroless gold plating bath of claim 1 or 2, wherein
a concentration of the hydrazine compounds is in a range of 0.5 g/L to 15 g/L and a concentration of the ascorbic acid compounds is in a range of 1 g/L to 20 gL. - The electroless gold plating bath of any one of claims 1 to 3, wherein
a mass ratio of gold in the gold sulfite to the thiosulfate is in a range of gold: thiosulfate = 1: 0.5 to 1: 10. - The electroless gold plating bath of any one of claims 1 to 4, further comprising:an anti-corrosion agent and an amine-based complexing agent, whereina mass ratio of the anti-corrosion agent to the amine-based complexing agent is in a range of anti-corrosion agent: amine-based complexing agent = 1: 0.5 to 1: 10.
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JP2021168259A JP2023058312A (en) | 2021-10-13 | 2021-10-13 | Electroless gold plating bath |
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EP (1) | EP4166690A1 (en) |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US5364460A (en) * | 1993-03-26 | 1994-11-15 | C. Uyemura & Co., Ltd. | Electroless gold plating bath |
EP0618308B1 (en) * | 1993-03-26 | 1998-06-17 | C. Uyemura & Co, Ltd | Electroless gold plating bath |
JP2013224496A (en) * | 2013-08-07 | 2013-10-31 | Japan Pure Chemical Co Ltd | Gold sulfite salt aqueous solution for gold plating solution |
JP2017025399A (en) * | 2015-07-28 | 2017-02-02 | 上村工業株式会社 | Non-cyanide electroless gold plating bath, and electroless gold plating method |
-
2021
- 2021-10-13 JP JP2021168259A patent/JP2023058312A/en active Pending
-
2022
- 2022-09-22 EP EP22197168.2A patent/EP4166690A1/en not_active Withdrawn
- 2022-09-30 CN CN202211209004.1A patent/CN115961273A/en active Pending
- 2022-10-04 US US17/959,847 patent/US20230111446A1/en active Pending
- 2022-10-07 KR KR1020220128622A patent/KR20230052819A/en unknown
- 2022-10-12 TW TW111138582A patent/TW202331000A/en unknown
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5364460A (en) * | 1993-03-26 | 1994-11-15 | C. Uyemura & Co., Ltd. | Electroless gold plating bath |
EP0618308B1 (en) * | 1993-03-26 | 1998-06-17 | C. Uyemura & Co, Ltd | Electroless gold plating bath |
JP2927142B2 (en) | 1993-03-26 | 1999-07-28 | 上村工業株式会社 | Electroless gold plating bath and electroless gold plating method |
JP2013224496A (en) * | 2013-08-07 | 2013-10-31 | Japan Pure Chemical Co Ltd | Gold sulfite salt aqueous solution for gold plating solution |
JP2017025399A (en) * | 2015-07-28 | 2017-02-02 | 上村工業株式会社 | Non-cyanide electroless gold plating bath, and electroless gold plating method |
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JP2023058312A (en) | 2023-04-25 |
TW202331000A (en) | 2023-08-01 |
CN115961273A (en) | 2023-04-14 |
KR20230052819A (en) | 2023-04-20 |
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