EP2143820B1 - An electroless gold plating solution - Google Patents
An electroless gold plating solution Download PDFInfo
- Publication number
- EP2143820B1 EP2143820B1 EP08160251A EP08160251A EP2143820B1 EP 2143820 B1 EP2143820 B1 EP 2143820B1 EP 08160251 A EP08160251 A EP 08160251A EP 08160251 A EP08160251 A EP 08160251A EP 2143820 B1 EP2143820 B1 EP 2143820B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- gold plating
- plating solution
- electroless gold
- pyridinium
- compound
- 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.)
- Ceased
Links
- 238000007747 plating Methods 0.000 title claims description 149
- 229910052737 gold Inorganic materials 0.000 title claims description 143
- 239000010931 gold Substances 0.000 title claims description 143
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims description 136
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 56
- 239000010953 base metal Substances 0.000 claims description 45
- -1 gold cyanide compound Chemical class 0.000 claims description 31
- 229910052759 nickel Inorganic materials 0.000 claims description 28
- 150000003839 salts Chemical class 0.000 claims description 27
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 26
- 150000001875 compounds Chemical class 0.000 claims description 21
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims description 14
- 125000003710 aryl alkyl group Chemical group 0.000 claims description 13
- 239000008139 complexing agent Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- 239000012756 surface treatment agent Substances 0.000 claims description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 10
- 229910052802 copper Inorganic materials 0.000 claims description 10
- 239000010949 copper Substances 0.000 claims description 10
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 10
- 229940120146 EDTMP Drugs 0.000 claims description 9
- NFDRPXJGHKJRLJ-UHFFFAOYSA-N edtmp Chemical group OP(O)(=O)CN(CP(O)(O)=O)CCN(CP(O)(O)=O)CP(O)(O)=O NFDRPXJGHKJRLJ-UHFFFAOYSA-N 0.000 claims description 9
- AVWFAACIXBQMBF-UHFFFAOYSA-N 1-benzylpyridin-1-ium-3-carboxylate Chemical compound [O-]C(=O)C1=CC=C[N+](CC=2C=CC=CC=2)=C1 AVWFAACIXBQMBF-UHFFFAOYSA-N 0.000 claims description 8
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical group OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 7
- KXDHJXZQYSOELW-UHFFFAOYSA-N Carbamic acid Chemical group NC(O)=O KXDHJXZQYSOELW-UHFFFAOYSA-N 0.000 claims description 6
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 5
- 235000019253 formic acid Nutrition 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical class NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 4
- 150000007942 carboxylates Chemical class 0.000 claims description 2
- 150000007513 acids Chemical class 0.000 claims 1
- 239000000243 solution Substances 0.000 description 79
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 30
- 238000005260 corrosion Methods 0.000 description 24
- 230000007797 corrosion Effects 0.000 description 24
- 239000007864 aqueous solution Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 16
- 238000000151 deposition Methods 0.000 description 16
- 230000008021 deposition Effects 0.000 description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 12
- 238000006467 substitution reaction Methods 0.000 description 12
- 238000012360 testing method Methods 0.000 description 11
- RVOHXVFJUMOILH-UHFFFAOYSA-N 1-benzylpyridin-1-ium-3-carboxylate;sodium Chemical compound [Na].[O-]C(=O)C1=CC=C[N+](CC=2C=CC=CC=2)=C1 RVOHXVFJUMOILH-UHFFFAOYSA-N 0.000 description 10
- 125000000217 alkyl group Chemical group 0.000 description 8
- 229910000679 solder Inorganic materials 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 239000001508 potassium citrate Substances 0.000 description 6
- QEEAPRPFLLJWCF-UHFFFAOYSA-K potassium citrate (anhydrous) Chemical compound [K+].[K+].[K+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O QEEAPRPFLLJWCF-UHFFFAOYSA-K 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 235000015870 tripotassium citrate Nutrition 0.000 description 6
- GSMCZRMXOTVCGF-UHFFFAOYSA-N 2-bromo-1-(5-methyl-1,2-oxazol-3-yl)ethanone Chemical compound CC1=CC(C(=O)CBr)=NO1 GSMCZRMXOTVCGF-UHFFFAOYSA-N 0.000 description 5
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 5
- 150000003863 ammonium salts Chemical class 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 5
- 229910052700 potassium Inorganic materials 0.000 description 5
- 239000011591 potassium Substances 0.000 description 5
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 5
- WFIZEGIEIOHZCP-UHFFFAOYSA-M potassium formate Chemical compound [K+].[O-]C=O WFIZEGIEIOHZCP-UHFFFAOYSA-M 0.000 description 5
- 229920002873 Polyethylenimine Polymers 0.000 description 4
- 235000014113 dietary fatty acids Nutrition 0.000 description 4
- 239000000194 fatty acid Substances 0.000 description 4
- 229930195729 fatty acid Natural products 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 4
- ABLZXFCXXLZCGV-UHFFFAOYSA-N phosphonic acid group Chemical group P(O)(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 4
- 159000000000 sodium salts Chemical class 0.000 description 4
- 239000000080 wetting agent Substances 0.000 description 4
- 230000002087 whitening effect Effects 0.000 description 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 3
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 125000003277 amino group Chemical group 0.000 description 3
- 125000003118 aryl group Chemical group 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229940071106 ethylenediaminetetraacetate Drugs 0.000 description 3
- 150000004665 fatty acids Chemical class 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 159000000001 potassium salts Chemical class 0.000 description 3
- 238000013112 stability test Methods 0.000 description 3
- CEGDSRUGKSIHHO-UHFFFAOYSA-N 1,2-diaminoethane-1,1,2,2-tetrol Chemical compound NC(O)(O)C(N)(O)O CEGDSRUGKSIHHO-UHFFFAOYSA-N 0.000 description 2
- KWYJDIUEHHCHCZ-UHFFFAOYSA-N 3-[2-[bis(2-carboxyethyl)amino]ethyl-(2-carboxyethyl)amino]propanoic acid Chemical compound OC(=O)CCN(CCC(O)=O)CCN(CCC(O)=O)CCC(O)=O KWYJDIUEHHCHCZ-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- 0 CC(C)(C)N(*)* Chemical compound CC(C)(C)N(*)* 0.000 description 2
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- YNAVUWVOSKDBBP-UHFFFAOYSA-N Morpholine Chemical compound C1COCCN1 YNAVUWVOSKDBBP-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- JTPLPDIKCDKODU-UHFFFAOYSA-N acetic acid;2-(2-aminoethylamino)ethanol Chemical compound CC(O)=O.CC(O)=O.CC(O)=O.NCCNCCO JTPLPDIKCDKODU-UHFFFAOYSA-N 0.000 description 2
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 235000015165 citric acid Nutrition 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- XLJMAIOERFSOGZ-UHFFFAOYSA-N cyanic acid Chemical compound OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 2
- TWBYWOBDOCUKOW-UHFFFAOYSA-N isonicotinic acid Chemical compound OC(=O)C1=CC=NC=C1 TWBYWOBDOCUKOW-UHFFFAOYSA-N 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- DNIAPMSPPWPWGF-UHFFFAOYSA-N monopropylene glycol Natural products CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 150000003009 phosphonic acids Chemical class 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- FBBHPHRBJLLIFM-UHFFFAOYSA-N pyridin-1-ium-1-carboxylate Chemical class [O-]C(=O)[N+]1=CC=CC=C1 FBBHPHRBJLLIFM-UHFFFAOYSA-N 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 description 1
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 1
- XRDDOFNRQAQXBV-UHFFFAOYSA-N 1-(3-phenylpropyl)pyridin-1-ium-3-carboxylate Chemical compound C1=CC=C(C=C1)CCC[N+]2=CC=CC(=C2)C(=O)[O-] XRDDOFNRQAQXBV-UHFFFAOYSA-N 0.000 description 1
- XSIJMXDLJWJXQI-UHFFFAOYSA-N 1-(3-phenylpropyl)pyridin-1-ium-4-carboxylate Chemical compound C1=CC=C(C=C1)CCC[N+]2=CC=C(C=C2)C(=O)[O-] XSIJMXDLJWJXQI-UHFFFAOYSA-N 0.000 description 1
- PLRVOBVOIXPSQQ-UHFFFAOYSA-N 1-(4-phenylbutyl)pyridin-1-ium-2-carboxylate Chemical compound C1=CC=C(C=C1)CCCC[N+]2=CC=CC=C2C(=O)[O-] PLRVOBVOIXPSQQ-UHFFFAOYSA-N 0.000 description 1
- XAMFKAGYDUTQTH-UHFFFAOYSA-N 1-(4-phenylbutyl)pyridin-1-ium-3-carboxylate Chemical compound C1=CC=C(C=C1)CCCC[N+]2=CC=CC(=C2)C(=O)[O-] XAMFKAGYDUTQTH-UHFFFAOYSA-N 0.000 description 1
- DWWALEJFQQTTOG-UHFFFAOYSA-N 1-(5-phenylpentyl)pyridin-1-ium-2-carboxylate Chemical compound C1=CC=C(C=C1)CCCCC[N+]2=CC=CC=C2C(=O)[O-] DWWALEJFQQTTOG-UHFFFAOYSA-N 0.000 description 1
- XTNVMDSYIHAHKK-UHFFFAOYSA-N 1-(5-phenylpentyl)pyridin-1-ium-3-carboxylate Chemical compound C1=CC=C(C=C1)CCCCC[N+]2=CC=CC(=C2)C(=O)[O-] XTNVMDSYIHAHKK-UHFFFAOYSA-N 0.000 description 1
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- CMWBVPFKUMRZPY-UHFFFAOYSA-N 1-benzylpyridin-1-ium-2-carboxylate Chemical compound [O-]C(=O)C1=CC=CC=[N+]1CC1=CC=CC=C1 CMWBVPFKUMRZPY-UHFFFAOYSA-N 0.000 description 1
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- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
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- 229910021529 ammonia Inorganic materials 0.000 description 1
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- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 150000001649 bromium compounds Chemical class 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 150000001913 cyanates Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229940090960 diethylenetriamine pentamethylene phosphonic acid Drugs 0.000 description 1
- DUYCTCQXNHFCSJ-UHFFFAOYSA-N dtpmp Chemical compound OP(=O)(O)CN(CP(O)(O)=O)CCN(CP(O)(=O)O)CCN(CP(O)(O)=O)CP(O)(O)=O DUYCTCQXNHFCSJ-UHFFFAOYSA-N 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 235000011087 fumaric acid Nutrition 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- JGLCONSOSSTGDG-UHFFFAOYSA-N gold(3+);tetracyanide Chemical compound [Au+3].N#[C-].N#[C-].N#[C-].N#[C-] JGLCONSOSSTGDG-UHFFFAOYSA-N 0.000 description 1
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 description 1
- 239000012493 hydrazine sulfate Substances 0.000 description 1
- 229910000377 hydrazine sulfate Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910000378 hydroxylammonium sulfate Inorganic materials 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 239000001630 malic acid Substances 0.000 description 1
- 235000011090 malic acid Nutrition 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 description 1
- 125000001624 naphthyl group Chemical group 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 125000001147 pentyl group Chemical group C(CCCC)* 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- AQSJGOWTSHOLKH-UHFFFAOYSA-N phosphite(3-) Chemical class [O-]P([O-])[O-] AQSJGOWTSHOLKH-UHFFFAOYSA-N 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 229920001281 polyalkylene Polymers 0.000 description 1
- 229920001515 polyalkylene glycol Polymers 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 229920002503 polyoxyethylene-polyoxypropylene Polymers 0.000 description 1
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 1
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 125000002914 sec-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 description 1
- 235000019254 sodium formate Nutrition 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 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
- C23C18/44—Coating with noble metals using reducing agents
-
- 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
- C23C18/54—Contact plating, i.e. electroless electrochemical plating
Definitions
- the present invention relates to an electroless gold plating solution. Furthermore, the present invention relates to an electroless gold plating solution which can be used to deposit gold on the surface of a metal such as nickel or copper.
- gold plating is used as a final surface treatment for electronic industrial components such as printed circuit boards, ceramic IC packages, ITO boards, and IC cards, and the like, from the standpoint of electrical conductance of gold, solderability, physical characteristics such as connectivity by thermal crimping, and oxidation resistance.
- electroless plating rather than electroplating is preferable for most of these electronic industrial components because of the need to perform gold plating on electrically independent components and components with complex shapes.
- a printed circuit board normally has electroless nickel plating on the surface of a base metal such as copper wiring, and often electroless gold plating is performed on the surface of the nickel.
- substitution gold plating solutions which deposit gold while dissolving the base metal such as nickel, and self-catalyzing electroless gold plating solutions which deposit gold by the effects of a reducing agent which has catalytic activity towards gold, are widely known.
- Substitution gold plating deposits gold by a substitution reaction between gold and the base metal, and even when self-catalyzing electroless gold plating is used, a substitution gold plating reaction is used when initiating the self catalyzing electroless gold plating reaction.
- deposition of gold begins because of a substitution reaction between the base metal and the gold.
- the substitution reaction in electroless gold plating uses the dissolution of the base metal as a driving force for depositing the gold.
- This substitution reaction is affected by the structure of the base metal such as the crystalline grain boundary, and the like, so there are differences in the level of dissolution of the base metal.
- the substitution reaction proceeds preferentially compared to other regions, and in other words, inconsistencies occur in the dissolution of the base metal. Corrosion of the base metal, beginning with the nonuniform dissolution of the base metal, causes problems such as local embrittlement of the base metal adhesion of the gold plating film obtained is degraded, and lower solder bonding strength.
- Substitution gold plating solutions with a cyan group further containing ammonium chloride in order to control the localized corrosion of the base metal for example, see Japanese unexamined patent application S59-6365 ), or further containing a nitrogen-containing compound as a gold deposition controlling agent (for example, see Japanese unexamined patent application 2000-144441 ), or further containing polyethyleneimine (for example, Japanese unexamined patent application 2003-13248 ) have been proposed.
- these electroless gold plating solutions have been able to reduce the corrosion of the nickel film, which is the base metal layer, to some degree, but there are problems with a reduction in the deposition speed of the gold plating film because the dissolution speed of the nickel film is decreased.
- WO 00/28108 discloses a non-electrolytic gold plating composition comprising an anti-gold agent such as pyridine that can inhibit excess local etching or corrosion by substitution reaction between the metal surface and gold during the plating process.
- An object of the present invention is to resolve the aforementioned problems, and to provide an electroless gold plating solution that can uniformly plate and can increase the adhesion to the base metal without corroding the base metal.
- the present invention is an electroless gold plating solution that is used to perform metal plating on the surface of a metal, comprising:
- the electroless gold plating solution of the present invention that is used to perform gold plating on the surface of a metal preferably, comprises:
- the electroless gold plating solution of the present invention By using the electroless gold plating solution of the present invention, undesired dissolving, or in other words corrosion, of the base metal can be suppressed, adhesion can be increased, a uniform gold plating film can be formed, and the deposition rate of the gold can be increased.
- the electroless gold plating solution of the present invention can deposit a favorable gold film with good appearance and solder bonding strength without causing localized corrosion of the base metal such as nickel.
- the electroless gold plating solution of the present invention is an aqueous solution containing a water soluble gold cyanide compound, a complexing agent, a pyridinium carboxylate compound having a phenyl group or a aralkyl group at the first position, and optionally containing a polycarboxylate, and at least one type of base metal surface treatment agent, such as formic acid or salt thereof, or a hydrazine or derivative thereof.
- the water soluble gold cyanide compound used with the present invention can be any gold cyanide compound without restrictions in particular so long as the gold cyanide compound is water soluble, can provide gold ions to the plating solution, and is conventionally used in gold plating solutions.
- Examples of this type of water soluble gold cyanide compound include potassium dicyanoaurate (I) and potassium tetracyanoaurate (III).
- the water soluble gold cyanide compound may be a single type, or two or more types may be blended and used.
- the electroless gold plating solution of the present invention suitably contains these water soluble gold cyanide compounds with a gold ion concentration of between 0.1 and 10 g/L, for example, and preferably between 0.5 and 5 g/L.
- the complexing agent used with the present invention can be any substance used in publicly known gold plating solutions so long as the substance is water soluble, can stably maintain the gold ion in the plating solution, and a plating bath containing this complexing agent will essentially not dissolve nickel, cobalt, or palladium.
- these complexing agents include organic phosphonic acids or salts thereof which have a plurality of phosphonic acid groups or salts thereof in a molecule, and aminocarboxylic acid or salt thereof, and the like. Phosphonic acids or salts thereof preferably have a group with the structure shown below for example.
- M and M' may be either the same or different, and is selected from a group consisting of hydrogen atom, sodium, potassium, and ammonium.
- the number of phosphoric acid groups or salts thereof in the compound is between 2 and 6, preferably between 2 and 5.
- the organic phosphonic acid used with the present invention preferably is a compound with the following construction.
- X 1 is a hydrogen atom, a C 1 through C 5 alkyl group, an aryl group, an arylalkyl group, an amino group, or a C 1 through C 5 alkyl group substituted with -OH, -COOM, or PO 3 MM'.
- M and M' are as defined above.
- m and n are integers and are either 0 or 1.
- alkyl group includes those with a straight chain or a branched chain.
- a "C 1 through C 5 alkyl” refers to an alkyl group with between 1 and 5 carbon atoms.
- An example of a C 1 through C 5 alkyl group is a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, or pentyl group, or the like.
- An example of an aryl group is a phenyl group or a naphthyl group or the like.
- An example of an arylalkyl group is one of the aforementioned alkyl groups with the aforementioned aryl groups as a substitution group.
- An example of an amino group is an amino group that has hydrogen atoms, and the aforementioned alkyl groups, or the like, on a nitrogen atom.
- X 2 is, for example, -CH 2 -, -CH(OH)-, -C(CH 3 )(OH)-, -CH(PO 3 MM')-, -C(CH 3 )(PO 3 MM')-, -CH(CH(COOM)- or -C(CH 3 )(COOM)-, or the like, and M and M' are as defined above.
- X 3 through X 7 are similar to the aforementioned X 1 . However, at least two of X 3 through X 7 are -PO3MM'.
- organic phosphonic acid examples include aminotrimethylene phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetramethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, as well as the sodium salt, potassium salt, or ammonium salt, or the like, thereof
- the complexing agent used in the present invention may be a single type, or maybe a blend of two or more types.
- aminocarboxylate examples include glycerin, imino diacetate, hydroxyethylethylenediamine triacetate, tetrahydroxyethylenediamine, dihydroxymethylethylenediamine diacetate, ethylenediamine tetraacetate, ethylenediaminetetrapropionic acid as well as sodium salts, potassium salts, and ammonium salts thereof.
- Examples of the aforementioned ethylenediamine derivative having a phosphoric acid group or salt thereof or an aminocarboxylate group or salt thereof included ethylenediaminetetramethylene phosphonic acid, hydroxyethylethylenediamine triacetate, tetrahydroxyethylenediamine, hydroxymethylethylenediamine diacetate, ethylenediamine tetraacetate, but ethylenediaminetetrapropionic acid, as well as sodium, potassium, and ammonium salts thereof, are preferably used as complexing agents with the present invention.
- the complexing agent used in the present invention is preferably used in a range between 0.005 and 0.8 mol/L, more preferably between 0.02 and 0.6 mol/L.
- the number of moles of complexing agent contained is preferably equivalent to or higher than the number of moles of gold ion present in the plating solution.
- the electroless gold plating solution of the present invention contains a pyridinium carboxylate compound with a phenyl group or an aralkyl group at the first position.
- These pyridinium carboxylate compounds with a phenyl group or an arylkyl group at the first position cause a uniform gold plating film to be deposited with fine deposition particles of gold that adhere to the base metal surface that is the surface of the plating subject, and suppresses the elution of the base metal by the action of suppressing the substitution reaction between the gold ions and the base metal in the electroless gold plating solution, while increasing the gold deposition rate.
- Examples of the pyridinium carboxylate compound with a phenyl group or an aralkyl group at the first position include 1-phenyl-pyridinium-2- carboxylic acid, 1-phenyl-pyridinium-3-carboxylic acid, and 1-phenyl-pyridinium-4-carboxylic acid, as well as 1-phenylalkylene-pyridinium carboxylate compounds such as 1-benzyl-pyridinium-2-carboxylic acid, 1-benzyl-pyridinium-3-carboxylic acid, 1-benzyl-pyridinium-4-carboxylic acid, 1-(phenylether)-pyridinium-2-carboxylic acid, 1-(phenylethyl)-pyridinium-3-carboxylic acid, 1-(phenylether)-pyridinium-4-carboxylic acid, 1-(phenylether)-pyridinium-4-carboxylic acid, 1-(phenylpropyl)-pyridinium-2-
- One of the preferable compounds of the pyridinium carboxylate compounds having a phenyl group or an aralkyl group at the first position is 1-benzyl-pyridinium-3-carboxylic acid or carboxylate thereof. These compounds may be used independently, or two or more types may be blended and used together.
- the pyridinium carboxylate compound having a phenyl group or an aralkyl group at the first position used with the present invention is used in a range between 0.1 and 100 g/L, preferably in a range between 5 and 30 g/L.
- the electroless gold plating solution of the present invention also comprises a base metal surface treatment agent.
- the base metal surface treatment agent used with the present invention is a substance which has the effect of reducing a metal that is in the oxidized state which is formed on the surface of a base metal selected from a group consisting of nickel, copper, cobalt, palladium, as well as alloys comprising these metals.
- These substances act as a reducing agent and preferentially oxidize the base metal over the gold ion, and when combined with a pyridinium carboxylate compound which has a phenyl group or an arakyl group at the first position, corrosion of the base metal is suppressed, adhesion is increased, a uniform gold plating film is formed, and the gold deposition rate is increased.
- Examples of the base metal surface treatment agent include formic acid and salts thereof, such as formic acid, sodium formate, potassium formate, ammonium formate; and hydrazine and derivatives thereof such as a hydrazine, hydrazine hydrate, as well as hydrazine sulfate, hydrazine chloride, and salts thereof.
- the base metal surface treatment agent used with the present invention may be used individually, or two or more types may be blended and used together.
- the base metal surface treatment agent used with the present invention is used in a range between 0.1 and 20 g/L, preferably in a range between 1 and 15 g/L.
- the electroless gold plating solution of the present invention preferably also comprises a polycarboxylic acid or salt thereof
- the polycarboxylic acid or salt thereof suppresses pinhole-type corrosion by adhering to the surface of the base metal, and stabilizes the plating solution by forming a salt that complexes with the base metal ions which have eluted into the plating solution.
- this polycarboxylic acid or salt thereof include oxalic acid, maleic acid, fumaric acid, malic acid, citric acid, adipic acid, as well as the sodium salt, potassium salts, or ammonium salt thereof, and the like. Citric acid or tripotassium citrate are preferable.
- the polycarboxylic acid or salt thereof may be used individually, or two or more types may be blended and used together.
- the polycarboxylic acid or salt thereof used with the present invention is present in a range, for example, between 0 and 100 g/L, preferably in a range between 30 and 75 g/L.
- the pH of the electroless gold plating solution of the present invention is between 5 and less than 7.
- the pH of the gold plating solution of the present invention is adjusted using, for instance, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sulfuric acid, sulfurous acid, HCl, phosphoric acid, cyanic acid, sulfamic acid, organic sulfonic acid, a phosphonic acid, or carboxylic acid, or the like.
- a pH stabilizer may also be provided. Examples of pH stabilizers include phosphates, phosphites, borates, carbonates, and cyanates, and the like.
- the electroless gold plating solution of the present invention may comprise a wetting agent in order to increase the wetness of the base metal that is the coating subject.
- the wetting agent can be used without restriction in particular so long as the wetting agent is a substance which has been conventionally used in gold plating solutions.
- wetting agent examples include nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether, polyoxyethylene polyoxy propylene glycol, fatty acid polyalkylene glycol, fatty acid polyalkylene sorbitans, and fatty acid alkanolamides; anionic surfactants such as fatty acid carboxylates, alkanesulfonates, alkylbenzene sulfonates; and cationic surfactants such as alkylamines, and the like.
- nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether, polyoxyethylene polyoxy propylene glycol, fatty acid polyalkylene glycol, fatty acid polyalkylene sorbitans, and fatty acid alkanolamides
- anionic surfactants such as fatty acid carboxylates, alkanesulfonates, alkylbenzene sulfonates
- the electroless gold plating solution of the present invention can also contain a glossing agent in order to further increase the gloss off the gold plating film and then to make the gold plating film particles more compact.
- the glossing agent can be used without restrictions in particular, so long as the glossing agent is a substance which has conventionally been used in gold plating solutions. Examples of the glossing agent include thallium, arsenic, lead, copper, antimony, and the like.
- the electroless gold plating solution of the present invention can contain other compounds than the aforementioned, to the degree that a negative effect is not had on the properties of the plating solution.
- the process can be the same as a normal electroless plating method.
- the plating subject is immersed in the electroless gold plating solution, and the electroless gold plating film can be formed on the surface of the base metal made of nickel, cobalt, copper, palladium, or alloys containing these metals, by maintaining the temperature of the plating solution within a prescribed range.
- the gold plating solution of the present invention can be suitably used as an electroless gold plating solution in order to deposit gold on the surface of a metal such as nickel or copper.
- the temperature (liquid temperature) of the gold plating solution is between 50°C and 100°C, preferably between 70°C and 95°C.
- the plating time is normally between 1 and 60 minutes, and preferably is between 10 and 30 minutes.
- the plating solution can be mixed, exchange filtered, or reflux filtered, but reflux filtering of the plating solution using a filter is particularly preferable.
- the electroless gold plating solution of the present invention has good stability, and can form a uniform gold plating film with good appearance at an increased gold deposition rate that has excellent adhesion to the base metal. Furthermore, the electroless gold plating solution of the present invention has excellent properties for minimizing grain boundary corrosion and pinhole corrosion of nickel plating when nickel is the base metal.
- an electroless nickel plating film with a thickness of approximately 5 ⁇ m was formed on a 5 cm x 10 cm patterned copper clad laminate using a commonly known electroless nickel plating solution (Ronamax (trademark) SMT-115 at electroless nickel plating solution, product of Rohm & Haas Electronic Materials Co. Ltd.).
- An electroless gold plating solution was prepared as an aqueous solution wherein water was added to 1.5 g/L of potassium dicyanoaurate, 50 mg/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 10 g/L of potassium formate, 94.3 g/L of potassium hydroxide, and 0.5 g/L of a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate.
- This electroless gold plating solution was adjusted to a pH of 5.3 by adding additional potassium hydroxide.
- the aforementioned test piece was immersed for 10 minutes in the electroless gold plating solution at a liquid temperature of 90°C to form a gold plating film.
- the film thickness of the gold plating film that was formed was measured using a fluorescent x-ray thickness meter, and the gold plating deposition rate was calculated. Furthermore, the color and the occurrence of a lack of deposition was evaluated by visually observing the gold plating film that was formed. The results are shown in Table 1.
- Electroless gold plating solutions were prepared similarly to Embodiment 1 with the exception that the compounds shown in the following Table 1 were used in the amounts shown in the table in place of the aqueous solution containing a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, electroless gold plating was performed, and the coating was observed. The results are shown in Table 1.
- Table 1 when the plating solutions of Embodiments 1 through 3 containing 1-benzyl-pyridinium-3-carboxylic acid were used, corrosion of the nickel plating which is the base metal was suppressed, and the gold plating deposition rate was clearly increased.
- the aqueous solutions shown in Table 2 and 3 were prepared as electroless gold plating solutions.
- the pH of each of the electroless gold plating solutions was adjusted by adding additional potassium hydroxide.
- a test piece was immersed in the electroless gold plating solution, and the appearance of the gold plating film that was obtained and the occurrence of corrosion of the nickel plating film was evaluated. The results are shown in Table 2 and Table 3.
- Electroless gold plating solutions were prepared similar to Embodiment 1, except that the amount of 1-benzyl-pyridinium-3-carboxylic acid added, the base metal treatment agent, and the pH of the plating solution were as shown in Table 5.
- the solder bonding strength was evaluated by the following method, and the bath stability was also evaluated.
- a test piece on which an electroless gold plating film was formed was subjected to reflow processing three times with a preheat temperature of 170°C and a reflow temperature of 240°C, and then a bowl mount was performed at the conditions shown in the following Table 4, and the solder bonding strength was measured.
- the test was performed using ten test pieces at each condition, and average value was calculated as the bonding strength. The results are shown in Table 5.
- Base metal surface treatment agent Amount of 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate (g/L) pH Bonding strength average value N Potassium formate 5 6.3 23.0 6.5 21.8 6.7 17.6 10 6.3 22.3 6.5 22.5 6.7 18.8 20 6.3 24.4 6.5 21.8 6.7 22.6 Hydrazine 15 6.3 23.4 6.5 24.2 6.7 22.8 20 6.3 23.9 6.5 23.9 6.7 24.0 25 6.3 24.2 6.5 22.6 6.7 23.1
- An aqueous solution with a pH of 6.5 was prepared as an electroless gold plating solution by adding 1.5 g/L of potassium dicyanoaurate, 50 m g/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 3.5 g/L of hydrazine, 20 g/L of a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, and 94.3 g/L of potassium hydroxide.
- electroless gold plating bath was prepared similar to the electroless gold plating bath of Embodiment 24, except that 20 g of potassium formate was used in place of the hydrazine.
- the stability test was performed on these plating solutions. The results are shown in Table 6.
- a plating solution was prepared by adding 56 g of tripotassium citrate to an aqueous solution of 1.5 g/L of potassium dicyanoaurate (I), 100 mg/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 7 g of hydrazine, 20 g/L of 48% aqueous solution containing a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, and 94.3 g/L of potassium hydroxide.
- the pH of the electroless gold plating solution was adjusted to 6.5 by adding additional potassium hydroxide.
- a gold plating film was formed similar to Embodiment 1, and the various tests were performed as described above.
- the gold plating solution which contained tripotassium citrate did not have a particularly noticeable difference for the deposition rate of the gold plating film, the appearance of the gold plating film, the solder bonding strength, and the bath stability, when compared with a gold plating solution which did not contain tripotassium citrate.
- a gold plating solution which contains tripotassium citrate is used, pinhole-type corrosion of the nickel plating film is significantly reduced.
- a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate as shown in the following Table 6 was added to an aqueous solution where 2 g/L of potassium dicyanoaurate (I), 45 g/L of ethylenediaminetetraacetate and 67.5 g/L of tripotassium citrate were added to water, and the pH of the aqueous solution was adjusted using potassium hydroxide.
- the test piece used in Embodiment 1 was immersed for 10 minutes in an electroless gold plating solution with a liquid temperature of 85°C to form a gold plating film.
- the gold plating film that was formed was stripped using a gold plating-stripping solution Enstrip AU-78M (product of Meltex Inc.), and the presence of corrosion on the surface of the nickel which was the base metal was observed using an FE-SEM JSM-7000F (product of JEOL, Ltd.).
- Pinhole-type corrosion of the nickel plating film was confirmed to be reduced by the addition of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate to the electroless gold plating solution.
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Description
- The present invention relates to an electroless gold plating solution. Furthermore, the present invention relates to an electroless gold plating solution which can be used to deposit gold on the surface of a metal such as nickel or copper.
- Conventionally, gold plating is used as a final surface treatment for electronic industrial components such as printed circuit boards, ceramic IC packages, ITO boards, and IC cards, and the like, from the standpoint of electrical conductance of gold, solderability, physical characteristics such as connectivity by thermal crimping, and oxidation resistance. Use of electroless plating rather than electroplating is preferable for most of these electronic industrial components because of the need to perform gold plating on electrically independent components and components with complex shapes.
- A printed circuit board normally has electroless nickel plating on the surface of a base metal such as copper wiring, and often electroless gold plating is performed on the surface of the nickel. For this case, substitution gold plating solutions which deposit gold while dissolving the base metal such as nickel, and self-catalyzing electroless gold plating solutions which deposit gold by the effects of a reducing agent which has catalytic activity towards gold, are widely known. Substitution gold plating deposits gold by a substitution reaction between gold and the base metal, and even when self-catalyzing electroless gold plating is used, a substitution gold plating reaction is used when initiating the self catalyzing electroless gold plating reaction. In other words, immediately after the self-catalyzing electroless gold plating solution and the plating subject come in contact, deposition of gold begins because of a substitution reaction between the base metal and the gold. The substitution reaction in electroless gold plating uses the dissolution of the base metal as a driving force for depositing the gold. This substitution reaction is affected by the structure of the base metal such as the crystalline grain boundary, and the like, so there are differences in the level of dissolution of the base metal. In regions where the metal is materially weaker such as at the crystalline grain boundaries, or the like, of the base metal, the substitution reaction proceeds preferentially compared to other regions, and in other words, inconsistencies occur in the dissolution of the base metal. Corrosion of the base metal, beginning with the nonuniform dissolution of the base metal, causes problems such as local embrittlement of the base metal adhesion of the gold plating film obtained is degraded, and lower solder bonding strength.
- Substitution gold plating solutions with a cyan group further containing ammonium chloride in order to control the localized corrosion of the base metal (for example, see Japanese unexamined patent application
S59-6365 2000-144441 2003-13248
WO 00/28108 - An object of the present invention is to resolve the aforementioned problems, and to provide an electroless gold plating solution that can uniformly plate and can increase the adhesion to the base metal without corroding the base metal.
- As result of diligent investigations to resolve the aforementioned problems, the present inventors have discovered that the aforementioned objective can be achieved by using an electroless gold plating solution that comprises a combination of specific components, and have thus achieved the present invention. In other words, the present invention is an electroless gold plating solution that is used to perform metal plating on the surface of a metal, comprising:
- (i) a water soluble gold cyanide compound;
- (ii) a complexing agent selected from ethylene diamine derivatives which have a phosphoric acid group or salt thereof, or an aminocarboxylic acid group or salt thereof;
- (iii) a pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position; and
- (iv) at least one compound selected from formic acid and salt thereof as well as hydrazine and derivative thereof, as a base metal surface treatment agent, and wherein the pH of the solution is between 5 and less than 7.
- Furthermore, the electroless gold plating solution of the present invention that is used to perform gold plating on the surface of a metal preferably, comprises:
- (i) a water soluble gold cyanide compound;
- (ii) a complexing agent with at least one type selected from ethylenediaminetetramethylene phosphonic acid or derivative thereof;
- (iii) at least one compound selected from a pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position;
- (iv) at least one compound selected from hydrazine and derivative thereof, as a base metal surface treatment agent; and
- (v) at least one compound selected from polycarboxylic acid and salts thereof.
- By using the electroless gold plating solution of the present invention, undesired dissolving, or in other words corrosion, of the base metal can be suppressed, adhesion can be increased, a uniform gold plating film can be formed, and the deposition rate of the gold can be increased.
- Furthermore, the electroless gold plating solution of the present invention can deposit a favorable gold film with good appearance and solder bonding strength without causing localized corrosion of the base metal such as nickel.
- The present invention will be described below in detail. The electroless gold plating solution of the present invention is an aqueous solution containing a water soluble gold cyanide compound, a complexing agent, a pyridinium carboxylate compound having a phenyl group or a aralkyl group at the first position, and optionally containing a polycarboxylate, and at least one type of base metal surface treatment agent, such as formic acid or salt thereof, or a hydrazine or derivative thereof.
- The water soluble gold cyanide compound used with the present invention can be any gold cyanide compound without restrictions in particular so long as the gold cyanide compound is water soluble, can provide gold ions to the plating solution, and is conventionally used in gold plating solutions. Examples of this type of water soluble gold cyanide compound include potassium dicyanoaurate (I) and potassium tetracyanoaurate (III). The water soluble gold cyanide compound may be a single type, or two or more types may be blended and used.
- The electroless gold plating solution of the present invention suitably contains these water soluble gold cyanide compounds with a gold ion concentration of between 0.1 and 10 g/L, for example, and preferably between 0.5 and 5 g/L.
- The complexing agent used with the present invention can be any substance used in publicly known gold plating solutions so long as the substance is water soluble, can stably maintain the gold ion in the plating solution, and a plating bath containing this complexing agent will essentially not dissolve nickel, cobalt, or palladium. Examples of these complexing agents include organic phosphonic acids or salts thereof which have a plurality of phosphonic acid groups or salts thereof in a molecule, and aminocarboxylic acid or salt thereof, and the like. Phosphonic acids or salts thereof preferably have a group with the structure shown below for example.
-PO3MM'
wherein M and M' may be either the same or different, and is selected from a group consisting of hydrogen atom, sodium, potassium, and ammonium. The number of phosphoric acid groups or salts thereof in the compound is between 2 and 6, preferably between 2 and 5. - The organic phosphonic acid used with the present invention preferably is a compound with the following construction.
-
- wherein X1 is a hydrogen atom, a C1 through C5 alkyl group, an aryl group, an arylalkyl group, an amino group, or a C1 through C5 alkyl group substituted with -OH, -COOM, or PO3MM'. M and M' are as defined above. Furthermore, m and n are integers and are either 0 or 1.
- Herein, the term "alkyl group" includes those with a straight chain or a branched chain. A "C1 through C5 alkyl" refers to an alkyl group with between 1 and 5 carbon atoms. An example of a C1 through C5 alkyl group is a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, or pentyl group, or the like. An example of an aryl group is a phenyl group or a naphthyl group or the like. An example of an arylalkyl group is one of the aforementioned alkyl groups with the aforementioned aryl groups as a substitution group. An example of an amino group is an amino group that has hydrogen atoms, and the aforementioned alkyl groups, or the like, on a nitrogen atom.
-
- wherein X2 is, for example, -CH2-, -CH(OH)-, -C(CH3)(OH)-, -CH(PO3MM')-, -C(CH3)(PO3MM')-, -CH(CH(COOM)- or -C(CH3)(COOM)-, or the like, and M and M' are as defined above.
-
- wherein X3 through X7 are similar to the aforementioned X1. However, at least two of X3 through X7 are -PO3MM'.
- Examples of the aforementioned organic phosphonic acid include aminotrimethylene phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetramethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, as well as the sodium salt, potassium salt, or ammonium salt, or the like, thereof The complexing agent used in the present invention may be a single type, or maybe a blend of two or more types.
- Examples of the aminocarboxylate include glycerin, imino diacetate, hydroxyethylethylenediamine triacetate, tetrahydroxyethylenediamine, dihydroxymethylethylenediamine diacetate, ethylenediamine tetraacetate, ethylenediaminetetrapropionic acid as well as sodium salts, potassium salts, and ammonium salts thereof.
- Examples of the aforementioned ethylenediamine derivative having a phosphoric acid group or salt thereof or an aminocarboxylate group or salt thereof, included ethylenediaminetetramethylene phosphonic acid, hydroxyethylethylenediamine triacetate, tetrahydroxyethylenediamine, hydroxymethylethylenediamine diacetate, ethylenediamine tetraacetate, but ethylenediaminetetrapropionic acid, as well as sodium, potassium, and ammonium salts thereof, are preferably used as complexing agents with the present invention.
- The complexing agent used in the present invention is preferably used in a range between 0.005 and 0.8 mol/L, more preferably between 0.02 and 0.6 mol/L. The number of moles of complexing agent contained is preferably equivalent to or higher than the number of moles of gold ion present in the plating solution.
- The electroless gold plating solution of the present invention contains a pyridinium carboxylate compound with a phenyl group or an aralkyl group at the first position. These pyridinium carboxylate compounds with a phenyl group or an arylkyl group at the first position cause a uniform gold plating film to be deposited with fine deposition particles of gold that adhere to the base metal surface that is the surface of the plating subject, and suppresses the elution of the base metal by the action of suppressing the substitution reaction between the gold ions and the base metal in the electroless gold plating solution, while increasing the gold deposition rate.
- Examples of the pyridinium carboxylate compound with a phenyl group or an aralkyl group at the first position include 1-phenyl-pyridinium-2- carboxylic acid, 1-phenyl-pyridinium-3-carboxylic acid, and 1-phenyl-pyridinium-4-carboxylic acid, as well as 1-phenylalkylene-pyridinium carboxylate compounds such as 1-benzyl-pyridinium-2-carboxylic acid, 1-benzyl-pyridinium-3-carboxylic acid, 1-benzyl-pyridinium-4-carboxylic acid, 1-(phenylether)-pyridinium-2-carboxylic acid, 1-(phenylethyl)-pyridinium-3-carboxylic acid, 1-(phenylether)-pyridinium-4-carboxylic acid, 1-(phenylether)-pyridinium-4-carboxylic acid, 1-(phenylpropyl)-pyridinium-2-carboxylic acid, 1-(phenylpropyl)-pyridinium-3-carboxylic acid, 1-(phenylpropyl)-pyridinium-4-carboxylic acid, 1-(phenylbutyl)-pyridinium-2-carboxylic acid, 1-(phenylbutyl)-pyridinium-3-carboxylic acid, 1-(phenylbutyl)-pyridinium-4-carboxylic acid, 1-(phenylpentyl)-pyridinium-2-carboxylic acid, 1-(phenylpentyl)-pyridinium-3-carboxylic acid, 1-(phenylpentyl)-pyridinium-4-carboxylic acid, as well as sodium salt, potassium salts, or ammonium salt of these carboxylic acids, as well as hydroxides, chlorides, and bromides of these compounds and the like. One of the preferable compounds of the pyridinium carboxylate compounds having a phenyl group or an aralkyl group at the first position is 1-benzyl-pyridinium-3-carboxylic acid or carboxylate thereof. These compounds may be used independently, or two or more types may be blended and used together.
- The pyridinium carboxylate compound having a phenyl group or an aralkyl group at the first position used with the present invention is used in a range between 0.1 and 100 g/L, preferably in a range between 5 and 30 g/L.
- The electroless gold plating solution of the present invention also comprises a base metal surface treatment agent. The base metal surface treatment agent used with the present invention is a substance which has the effect of reducing a metal that is in the oxidized state which is formed on the surface of a base metal selected from a group consisting of nickel, copper, cobalt, palladium, as well as alloys comprising these metals. These substances act as a reducing agent and preferentially oxidize the base metal over the gold ion, and when combined with a pyridinium carboxylate compound which has a phenyl group or an arakyl group at the first position, corrosion of the base metal is suppressed, adhesion is increased, a uniform gold plating film is formed, and the gold deposition rate is increased.
- Examples of the base metal surface treatment agent include formic acid and salts thereof, such as formic acid, sodium formate, potassium formate, ammonium formate; and hydrazine and derivatives thereof such as a hydrazine, hydrazine hydrate, as well as hydrazine sulfate, hydrazine chloride, and salts thereof. The base metal surface treatment agent used with the present invention may be used individually, or two or more types may be blended and used together.
- The base metal surface treatment agent used with the present invention is used in a range between 0.1 and 20 g/L, preferably in a range between 1 and 15 g/L.
- The electroless gold plating solution of the present invention preferably also comprises a polycarboxylic acid or salt thereof The polycarboxylic acid or salt thereof suppresses pinhole-type corrosion by adhering to the surface of the base metal, and stabilizes the plating solution by forming a salt that complexes with the base metal ions which have eluted into the plating solution. Examples of this polycarboxylic acid or salt thereof include oxalic acid, maleic acid, fumaric acid, malic acid, citric acid, adipic acid, as well as the sodium salt, potassium salts, or ammonium salt thereof, and the like. Citric acid or tripotassium citrate are preferable. The polycarboxylic acid or salt thereof may be used individually, or two or more types may be blended and used together.
- The polycarboxylic acid or salt thereof used with the present invention is present in a range, for example, between 0 and 100 g/L, preferably in a range between 30 and 75 g/L.
- The pH of the electroless gold plating solution of the present invention is between 5 and less than 7. The pH of the gold plating solution of the present invention is adjusted using, for instance, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sulfuric acid, sulfurous acid, HCl, phosphoric acid, cyanic acid, sulfamic acid, organic sulfonic acid, a phosphonic acid, or carboxylic acid, or the like. Furthermore, if necessary a pH stabilizer may also be provided. Examples of pH stabilizers include phosphates, phosphites, borates, carbonates, and cyanates, and the like.
- If necessary, the electroless gold plating solution of the present invention may comprise a wetting agent in order to increase the wetness of the base metal that is the coating subject. The wetting agent can be used without restriction in particular so long as the wetting agent is a substance which has been conventionally used in gold plating solutions. Examples of the wetting agent include nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether, polyoxyethylene polyoxy propylene glycol, fatty acid polyalkylene glycol, fatty acid polyalkylene sorbitans, and fatty acid alkanolamides; anionic surfactants such as fatty acid carboxylates, alkanesulfonates, alkylbenzene sulfonates; and cationic surfactants such as alkylamines, and the like.
- If necessary, the electroless gold plating solution of the present invention can also contain a glossing agent in order to further increase the gloss off the gold plating film and then to make the gold plating film particles more compact. The glossing agent can be used without restrictions in particular, so long as the glossing agent is a substance which has conventionally been used in gold plating solutions. Examples of the glossing agent include thallium, arsenic, lead, copper, antimony, and the like. The electroless gold plating solution of the present invention can contain other compounds than the aforementioned, to the degree that a negative effect is not had on the properties of the plating solution.
- When performing the gold plating using the electroless gold plating solution of the present invention, the process can be the same as a normal electroless plating method. Generally, the plating subject is immersed in the electroless gold plating solution, and the electroless gold plating film can be formed on the surface of the base metal made of nickel, cobalt, copper, palladium, or alloys containing these metals, by maintaining the temperature of the plating solution within a prescribed range. For instance, the gold plating solution of the present invention can be suitably used as an electroless gold plating solution in order to deposit gold on the surface of a metal such as nickel or copper.
- When performing gold plating using the electroless gold plating solution of the present invention, the temperature (liquid temperature) of the gold plating solution is between 50°C and 100°C, preferably between 70°C and 95°C. The plating time is normally between 1 and 60 minutes, and preferably is between 10 and 30 minutes. When performing gold plating using the electroless gold plating solution of the present invention, the plating solution can be mixed, exchange filtered, or reflux filtered, but reflux filtering of the plating solution using a filter is particularly preferable.
- The electroless gold plating solution of the present invention has good stability, and can form a uniform gold plating film with good appearance at an increased gold deposition rate that has excellent adhesion to the base metal. Furthermore, the electroless gold plating solution of the present invention has excellent properties for minimizing grain boundary corrosion and pinhole corrosion of nickel plating when nickel is the base metal.
- Embodiments of the present invention will be presented below, but the present invention is not restricted to these embodiments.
- For a test piece, an electroless nickel plating film with a thickness of approximately 5 µm was formed on a 5 cm x 10 cm patterned copper clad laminate using a commonly known electroless nickel plating solution (Ronamax (trademark) SMT-115 at electroless nickel plating solution, product of Rohm & Haas Electronic Materials Co. Ltd.).
- An electroless gold plating solution was prepared as an aqueous solution wherein water was added to 1.5 g/L of potassium dicyanoaurate, 50 mg/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 10 g/L of potassium formate, 94.3 g/L of potassium hydroxide, and 0.5 g/L of a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate. This electroless gold plating solution was adjusted to a pH of 5.3 by adding additional potassium hydroxide.
- The aforementioned test piece was immersed for 10 minutes in the electroless gold plating solution at a liquid temperature of 90°C to form a gold plating film. The film thickness of the gold plating film that was formed was measured using a fluorescent x-ray thickness meter, and the gold plating deposition rate was calculated. Furthermore, the color and the occurrence of a lack of deposition was evaluated by visually observing the gold plating film that was formed. The results are shown in Table 1.
- The gold plating film that was formed was peeled using a gold plating stripping solution Enstrip AU-78M (product of Meltex Inc.), and the occurrence of corrosion on the surface of the nickel which was the base metal was observed using a FE-SEM JSM-7000F (product of JEOL Ltd.). The observation results are shown in Table 1 where 1 = good, 2 = fairly good (minimal corrosion), 3 = partially corroded, 4 = fairly heavily corroded, and 5 = heavy corrosion.
- Electroless gold plating solutions were prepared similarly to Embodiment 1 with the exception that the compounds shown in the following Table 1 were used in the amounts shown in the table in place of the aqueous solution containing a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, electroless gold plating was performed, and the coating was observed. The results are shown in Table 1.
-
Table 1 Compound Amount g/L Deposition Rate µm/10 minutes Gold Plating Film Appearance Nickel Plating Film Corrosion Embodiment 1 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate (g/L) 0.5 0.092 Good 2 Comparative Example 1 Reaction product of imidazole and epichlorohydrin 0.5 0.029 Good 3 Comparative Example 2 Sulfopropylpolyethyleneimine 0.5 0.041 Good 2 Comparative Example 3 Reaction product of morpholine and epichlorohydrin 0.5 0.036 Good 3 Comparative Example 4 Dimethylaminoethylmethacrylate quaternary compound 0.5 0.029 Good 3 Comparative Example 5 Reaction product of dimethylamine, ammonia, and epichlorohydrin 0.5 0.026 Good 3 Comparative Example 6 Polyethyleneimine (weighted average molecular weight 1300) 0.5 0.010 Good 1 Comparative Example 7 Polyethyleneimine (weighted average molecular weight 2000) 0.5 0.012 Good 1 Embodiment 2 48% aqueous solution of a chloride of 1-benzyl-pyridinium-3-carboxylate (g/L) 1.0 0.090 Good 2 Embodiment 3 48% aqueous solution of a chloride of 1-benzyl-pyridinium-3-carboxylate (g/L) 5.0 0.071 Good 2 Comparative Example 8 Polyvinylpyrrolidone (weighted average molecular weight 5000) 0.5 0.066 Good 3 Comparative Example 9 Picoric acid 5.0 0.120 Good 4 Comparative Example 10 Isonicotinic acid 5.0 0.109 Good 4 Comparative Example 11 3-picorinamine 5.0 0.111 Good 5 Comparative Example 12 4-phenylpropyl-pyiidine N.A. N.A. N.A. N.A. - The gold plating solution containing 4-phenylpropyl-pyridine which was used as Comparative Example 12 separated as oil, and gold plating was not possible.
As shown in Table 1, when the plating solutions of Embodiments 1 through 3 containing 1-benzyl-pyridinium-3-carboxylic acid were used, corrosion of the nickel plating which is the base metal was suppressed, and the gold plating deposition rate was clearly increased. - The aqueous solutions shown in Table 2 and 3 were prepared as electroless gold plating solutions. The pH of each of the electroless gold plating solutions was adjusted by adding additional potassium hydroxide. Similar to Embodiment 1, a test piece was immersed in the electroless gold plating solution, and the appearance of the gold plating film that was obtained and the occurrence of corrosion of the nickel plating film was evaluated. The results are shown in Table 2 and Table 3.
-
Table 2 Embodiments Comparison Examples 4 5 6 7 8 9 10 11 12 13 14 15 13 14 Potassium dicyanoaurate (I) (g/L) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 L.5 1.5 1.5 1.5 1.5 Potassium cyanide (mg/L) 50 50 50 50 50 50 50 50 50 50 50 50 50 50 Ethylenediaminetetramethylene phosphonic acid (g/L) 150 150 150 150 150 150 150 150 150 150 150 150 150 150 Potassium hydroxide (g/L) 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 Potassium formate (g/L) 10 10 10 10 10 10 10 10 10 10 10 10 10 10 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate (g/L) 5 5 10 10 10 20 20 20 30 30 50 50 pH 5.0 6.0 5.0 6.0 7.0 6.0 6.5 7.0 6.5 7.0 6.5 7.0 5.3 6.0 Gold deposition rate (µm/10 0 minutes) 0.084 0.090 0.069 0.089 0.100 0.061 0.061 0.079 0.064 0.075 0.055 0.061 0.111 0.104 Appearance of gold plating film Good Good Good Good Good Good Good Good Good Good Good Good Good Good Corrosion of nickel plating film 2 2 2 2 2-3 2 2 2-3 2 2-3 2 2-3 3 3 -
Table 3 Embodiments Comparison Examples 16 17 18 19 20 21 22 15 16 17 18 Potassium dicyanoaurate (I) (g/L) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Potassium cyanide (mg/L) 50 50 50 50 50 50 50 50 50 50 50 Ethylenediaminetetramethylene phosphonic acid (g/L) 150 150 150 150 150 150 150 150 150 150 150 Potassium hydroxide (g/L) 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 94.3 Hydrazine (g/L) 3.5 3.5 3.5 3.5 3.5 3.5 3.5 Hydroxylamine sulfate (g/L) 1 1 Hydroxylamine chloride (g/L) 1 1 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate (g/L) 5 5 5 15 20 20 20 20 20 20 20 pH 5.0 6.5 7.0 6.5 6.0 6.5 6.7 6.0 6.5 6.0 6.5 Gold deposition rate (µm/10 minutes) 0.073 0.081 0.093 0.068 0.056 0.079 0.065 0.098 0.105 0.114 0.120 Appearance of gold plating film Good Good Good Good Good Good Good White ning White ning White ning White ning Corrosion of nickel plating film 2 2 2 2 2 1-2 2 5 5 5 5 - Electroless gold plating solutions were prepared similar to Embodiment 1, except that the amount of 1-benzyl-pyridinium-3-carboxylic acid added, the base metal treatment agent, and the pH of the plating solution were as shown in Table 5. The solder bonding strength was evaluated by the following method, and the bath stability was also evaluated.
- A test piece on which an electroless gold plating film was formed was subjected to reflow processing three times with a preheat temperature of 170°C and a reflow temperature of 240°C, and then a bowl mount was performed at the conditions shown in the following Table 4, and the solder bonding strength was measured. The test was performed using ten test pieces at each condition, and average value was calculated as the bonding strength. The results are shown in Table 5.
-
Table 4 Pad diameter 0.50 mm Solder ball Diameter 0.76 mm lead free solder (96.5% tin, 3% silver, 0.5% copper) Pre-heat 170°C Reflow 240°C/30 seconds Peak 270°C Flux Sparkle flux ES-1061 (product of Senju Metal Industry Co., Ltd.) -
Table 5 Base metal surface treatment agent Amount of 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate (g/L) pH Bonding strength average value N Potassium formate 5 6.3 23.0 6.5 21.8 6.7 17.6 10 6.3 22.3 6.5 22.5 6.7 18.8 20 6.3 24.4 6.5 21.8 6.7 22.6 Hydrazine 15 6.3 23.4 6.5 24.2 6.7 22.8 20 6.3 23.9 6.5 23.9 6.7 24.0 25 6.3 24.2 6.5 22.6 6.7 23.1 - 100 mL of electroless gold plating solution was poured into a screw tube without a lid, heated to a liquid temperature of 90°C using a water bath, and the time until the electroless gold plating solution separated under these conditions was measured in order to evaluate the stability of the bath.
- An aqueous solution with a pH of 6.5 was prepared as an electroless gold plating solution by adding 1.5 g/L of potassium dicyanoaurate, 50 m g/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 3.5 g/L of hydrazine, 20 g/L of a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, and 94.3 g/L of potassium hydroxide.
- As electroless gold plating bath was prepared similar to the electroless gold plating bath of Embodiment 24, except that 20 g of potassium formate was used in place of the hydrazine. The stability test was performed on these plating solutions. The results are shown in Table 6.
- As a conventional electroless gold plating solution, a plating solution that contained polyethyleneimine in place of the 1-benzyl-pyridinium-3-carboxylic acid (Aurolectroless (trademark) SMT-250 electroless gold plating solution, product of Rohm & Haas Electronic Materials Co. Ltd.) was subjected to a stability test as a comparative example. The results are shown in Table 6.
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Table 6 Decomposition start time Appearance Embodiment 24 24 hours black precipitate Embodiment 25 28 hours black precipitate Comparative example 19 22 hours decomposition - As an electroless gold plating solution, a plating solution was prepared by adding 56 g of tripotassium citrate to an aqueous solution of 1.5 g/L of potassium dicyanoaurate (I), 100 mg/L of potassium cyanide, 150 g/L of ethylenediaminetetramethylene phosphonic acid, 7 g of hydrazine, 20 g/L of 48% aqueous solution containing a chloride of sodium 1-benzyl-pyridinium-3-carboxylate, and 94.3 g/L of potassium hydroxide. The pH of the electroless gold plating solution was adjusted to 6.5 by adding additional potassium hydroxide. Using this electroless gold plating solution, a gold plating film was formed similar to Embodiment 1, and the various tests were performed as described above.
- The gold plating solution which contained tripotassium citrate did not have a particularly noticeable difference for the deposition rate of the gold plating film, the appearance of the gold plating film, the solder bonding strength, and the bath stability, when compared with a gold plating solution which did not contain tripotassium citrate. However, when a gold plating solution which contains tripotassium citrate is used, pinhole-type corrosion of the nickel plating film is significantly reduced.
- As an electroless gold plating solution, a 48% aqueous solution of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate as shown in the following Table 6 was added to an aqueous solution where 2 g/L of potassium dicyanoaurate (I), 45 g/L of ethylenediaminetetraacetate and 67.5 g/L of tripotassium citrate were added to water, and the pH of the aqueous solution was adjusted using potassium hydroxide.
- The test piece used in Embodiment 1 was immersed for 10 minutes in an electroless gold plating solution with a liquid temperature of 85°C to form a gold plating film. The gold plating film that was formed was stripped using a gold plating-stripping solution Enstrip AU-78M (product of Meltex Inc.), and the presence of corrosion on the surface of the nickel which was the base metal was observed using an FE-SEM JSM-7000F (product of JEOL, Ltd.). The observation results are shown in Table 7 where 1 = good, 2 = fair good (minimal corrosion), 3 = partially corroded, 4 = fairly heavily corroded, and 5 = heavy corrosion.
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Table 7 Amount added pH Corrosion of nickel plating film Comparative Example 20 0 5.5 5 Embodiment 27 10 5.5 3 Embodiment 28 20 5.5 3 Embodiment 29 30 5.5 3 Embodiment 30 40 5.5 3 Embodiment 31 20 5.0 3 - Pinhole-type corrosion of the nickel plating film was confirmed to be reduced by the addition of a chloride of sodium 1-benzyl-pyridinium-3-carboxylate to the electroless gold plating solution.
Claims (8)
- An electroless gold plating solution that is used to perform metal plating on the surface of a metal, comprising:(i) a water soluble gold cyanide compound;(ii) a complexing agent selected from ethylene diamine derivatives which have a phosphoric acid group or salt thereof, or an aminocarboxylic acid group or salt thereof;(iii) at least on compound selected from a pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position; and(iv) at least one compound selected from formic acid and salts thereof as well as hydrazine and derivatives thereof, as a base metal surface treatment agent, and wherein the pH of the solution is between 5 and less than 7.
- The electroless gold plating solution according to claim 1, wherein the base metal surface treatment agent is a compound selected from hydrazine and derivatives thereof.
- The electroless gold plating solution according to claim 1, wherein the complexing agent is at least one compound selected from ethylene diamine derivatives which have a phosphoric acid group or salt thereof or an aminocarboxylic acid group or salt thereof.
- The electroless gold plating solution according to claim 1, wherein the pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position is at least one compound selected from 1-phenylarakylene-pyridinium carboxylate compound.
- The electroless gold plating solution according to claim 1, further containing (v) at least one compound selected from polycarboxylic acid and salts thereof.
- An electroless gold plating solution of claim 1, that is used to perform gold plating on the surface of nickel or copper, wherein:(ii) the a complexing agent is selected from ethylenediaminetetramethylene phosphonic acid or derivative thereof;(iv) the at least one compound (iv) is selected from hydrazine and derivative thereof; and further comprising(v) at least one compound selected from polycarboxylic acids and salts thereof.
- The electroless gold plating solution according to claim 6, wherein the pyridinium carboxylate compound having a phenyl group or an aralkyl group in the first position is 1-benzyl-pyridinium-3-carboxylic acid or carboxylate thereof.
- A method of electrolessly plating gold on nickel or copper using the electroless gold plating solution of claim 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP08160251A EP2143820B1 (en) | 2008-07-11 | 2008-07-11 | An electroless gold plating solution |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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EP08160251A EP2143820B1 (en) | 2008-07-11 | 2008-07-11 | An electroless gold plating solution |
Publications (2)
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EP2143820A1 EP2143820A1 (en) | 2010-01-13 |
EP2143820B1 true EP2143820B1 (en) | 2012-03-07 |
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EP08160251A Ceased EP2143820B1 (en) | 2008-07-11 | 2008-07-11 | An electroless gold plating solution |
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Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS596365A (en) | 1982-06-30 | 1984-01-13 | Toshiba Corp | Electroless gold plating method |
CH662583A5 (en) * | 1985-03-01 | 1987-10-15 | Heinz Emmenegger | GALVANIC BATH FOR THE ELECTROLYTIC DEPOSITION OF GOLD-COPPER-CADMIUM-ZINC ALLOYS. |
JP4116718B2 (en) | 1998-11-05 | 2008-07-09 | 日本リーロナール有限会社 | Electroless gold plating method and electroless gold plating solution used therefor |
JP4932094B2 (en) | 2001-07-02 | 2012-05-16 | 日本リーロナール有限会社 | Electroless gold plating solution and electroless gold plating method |
JP4421367B2 (en) * | 2004-04-23 | 2010-02-24 | 日本高純度化学株式会社 | Replacement type electroless gold plating solution |
JP4932542B2 (en) * | 2007-03-05 | 2012-05-16 | ローム・アンド・ハース・エレクトロニック・マテリアルズ,エル.エル.シー. | Electroless gold plating solution |
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2008
- 2008-07-11 EP EP08160251A patent/EP2143820B1/en not_active Ceased
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