GB2114159A - Method and bath for the electroless plating of gold - Google Patents
Method and bath for the electroless plating of gold Download PDFInfo
- Publication number
- GB2114159A GB2114159A GB08232572A GB8232572A GB2114159A GB 2114159 A GB2114159 A GB 2114159A GB 08232572 A GB08232572 A GB 08232572A GB 8232572 A GB8232572 A GB 8232572A GB 2114159 A GB2114159 A GB 2114159A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bath
- gold
- litre
- aminoborane
- moles
- 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.)
- Granted
Links
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 42
- 239000010931 gold Substances 0.000 title claims abstract description 42
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims abstract description 12
- 238000007772 electroless plating Methods 0.000 title claims abstract description 11
- TVJORGWKNPGCDW-UHFFFAOYSA-N aminoboron Chemical group N[B] TVJORGWKNPGCDW-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003446 ligand Substances 0.000 claims abstract description 13
- 239000003381 stabilizer Substances 0.000 claims abstract description 12
- 239000007864 aqueous solution Substances 0.000 claims abstract description 9
- 239000000243 solution Substances 0.000 claims description 20
- 238000007747 plating Methods 0.000 claims description 12
- UFXPFCDHJCIVDO-UHFFFAOYSA-N [di(propan-2-yl)amino]boron Chemical group CC(C)N([B])C(C)C UFXPFCDHJCIVDO-UHFFFAOYSA-N 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 7
- 150000003839 salts Chemical class 0.000 claims description 6
- 229910019142 PO4 Inorganic materials 0.000 claims description 5
- 235000011180 diphosphates Nutrition 0.000 claims description 5
- -1 gold ions Chemical class 0.000 claims description 5
- 235000021317 phosphate Nutrition 0.000 claims description 5
- 230000003197 catalytic effect Effects 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 3
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 3
- 239000002574 poison Substances 0.000 claims description 3
- 231100000614 poison Toxicity 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- UOMBONFALRJTIP-UHFFFAOYSA-N morpholin-4-ylborane Chemical class BN1CCOCC1 UOMBONFALRJTIP-UHFFFAOYSA-N 0.000 claims description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims 2
- 150000001450 anions Chemical class 0.000 claims 2
- 150000001642 boronic acid derivatives Chemical class 0.000 claims 2
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 claims 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims 2
- 239000010452 phosphate Substances 0.000 claims 2
- 150000001449 anionic compounds Chemical class 0.000 claims 1
- 229910001412 inorganic anion Inorganic materials 0.000 claims 1
- 150000002500 ions Chemical class 0.000 claims 1
- 229940071240 tetrachloroaurate Drugs 0.000 claims 1
- 239000003638 chemical reducing agent Substances 0.000 abstract description 11
- HOASVNMVYBSLSU-UHFFFAOYSA-N 6-ethoxy-3h-1,3-benzothiazole-2-thione Chemical compound CCOC1=CC=C2N=C(S)SC2=C1 HOASVNMVYBSLSU-UHFFFAOYSA-N 0.000 abstract description 4
- YXIWHUQXZSMYRE-UHFFFAOYSA-N 1,3-benzothiazole-2-thiol Chemical compound C1=CC=C2SC(S)=NC2=C1 YXIWHUQXZSMYRE-UHFFFAOYSA-N 0.000 description 12
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- BORTXUKGEOWSPS-UHFFFAOYSA-N n-dimethylboranylmethanamine Chemical compound CNB(C)C BORTXUKGEOWSPS-UHFFFAOYSA-N 0.000 description 8
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 3
- NVIFVTYDZMXWGX-UHFFFAOYSA-N sodium metaborate Chemical compound [Na+].[O-]B=O NVIFVTYDZMXWGX-UHFFFAOYSA-N 0.000 description 3
- 229940005648 tetrachloroaurate ion Drugs 0.000 description 3
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910003252 NaBO2 Inorganic materials 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 150000002825 nitriles Chemical class 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 235000017550 sodium carbonate Nutrition 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 2
- 235000019801 trisodium phosphate Nutrition 0.000 description 2
- APGLXTXFTYAQKC-UHFFFAOYSA-N 2,5-dihydroxybenzonitrile Chemical class OC1=CC=C(O)C(C#N)=C1 APGLXTXFTYAQKC-UHFFFAOYSA-N 0.000 description 1
- MPAIWVOBMLSHQA-UHFFFAOYSA-N 3,6-dihydroxybenzene-1,2-dicarbonitrile Chemical compound OC1=CC=C(O)C(C#N)=C1C#N MPAIWVOBMLSHQA-UHFFFAOYSA-N 0.000 description 1
- ZILKBTSQUZJHOI-UHFFFAOYSA-N 3-ethyl-2-sulfanylidene-1,3-oxazolidin-4-one Chemical compound CCN1C(=O)COC1=S ZILKBTSQUZJHOI-UHFFFAOYSA-N 0.000 description 1
- YEMFHJFNJPXYOE-UHFFFAOYSA-N 3-iodo-1h-pyridin-2-one Chemical compound OC1=NC=CC=C1I YEMFHJFNJPXYOE-UHFFFAOYSA-N 0.000 description 1
- XOKVMSCOQFMZNC-UHFFFAOYSA-N 6-ethoxysulfanyl-1,3-benzothiazole Chemical compound CCOSC1=CC=C2N=CSC2=C1 XOKVMSCOQFMZNC-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- RRGHOLNUZYWMCL-UHFFFAOYSA-N CBN1CCOCC1 Chemical compound CBN1CCOCC1 RRGHOLNUZYWMCL-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 206010070834 Sensitisation Diseases 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- KKAXNAVSOBXHTE-UHFFFAOYSA-N boranamine Chemical group NB KKAXNAVSOBXHTE-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 1
- 230000005802 health problem Effects 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 210000003692 ilium Anatomy 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000005527 organic iodine compounds Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000008313 sensitization Effects 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 235000011008 sodium phosphates Nutrition 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003512 tertiary amines Chemical class 0.000 description 1
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical class Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 description 1
- 230000007306 turnover Effects 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
Abstract
The invention relates to a method and bath for the electroless plating of gold using an aqueous solution of trivalent gold, a ligand and a tertiary or secondary aminoborane as a reducing agent. Preferably, a stabilizer such as 6-ethoxy-2-mercaptobenzothiazole is used in the bath.
Description
SPECIFICATION
Method and bath for the electroless plating of gold
The invention relates to a the electroless plating of gold without the use of a cyanide complex.
Electroless gold plating, that is where gold is deposited on a catalytic surface without the use of electricity, is becoming a known and recognized method. Many of the methods of electroless gold plating utilize a cyanide to form a complex with the gold (see U.S. Patents Nos.
3,700,469 and 4,162,337) or utilize a cyanide to stabilize the bath (see U.S. Patent No. 3,589,916).
Where a cyanide is used, a strong reducing agent such as an alkali metal borohydride or an alkylaminoborane must also be used. The use of cyanides, however creates disposal and health problems which are preferably avoided.
One method for the electroless deposition of gold without the use of cyanide has been described in U.S. Patent No. 4,142,902.
Disclosed therein is the use of a soluble ethersubstituted tertiary aminoborane as a reducing agent. The plating baths of that invention meet the environmental objectives, but the plating rate has been slower than commercially desirable, and bath stability at elevated temperature is poor.
According to the present invention there is provided a bath for the electroless plating of gold upon a substrate, the bath comprising an aqueous solution of (a) gold complexed with an inorganic ligand, and (b) a secondary or tertiary aminoborane, the solution having a pH of from 8.5 to 14.
The bath of the present invention affords commercially desirable plating rates at elevated temperatures, but does not involve the use of cyanides either as a complexing agent or as a bath stabilizer.
Generally, the present invention involves the use of a stable aqueous bath comprising a soluble salt of tetrachloroaurate ion and at least one inorganic ligand which complexes with the gold.
A water soluble tertiary aminoborane or the secondary aminoborane diisopropylaminoborane is used as the reducing agent. Preferably, catalytic poison stabilizers are added when bath temperatures above 350C are used. These stabilizers inhibit the spontaneous decomposition of the bath. The pH of the bath is maintained between 8.5 and 14.
In a method preparing the-bath of the present invention, it is necessary to heat, preferably to boiling, an aqueous solution containing the gold anion and the ligand. The reducing agent and stabilizer are then added to the solution after it has cooled. In the event the gold anion and ligand are mixed together without heating, the bath will rapidly decompose upon the addition of the reducing agent.
It is preferable to use soluble salts such as
KAuCI4 or NaAuCI4 to prepare the gold solution.
The preferred range of gold concentration is from 0.001 to 0.05 moles/litre, more preferably from 0.003 to 0.006 moles/litre. The most desirable inorganic ligands to buffer the gold and to complex with it include inorganic berates, o- and m-silicates, phosphates, pyrophosphates and carbonates. Specifically, sodium metaborate in an amount from 0.06 to 6.0 moles/litre, sodium phosphate in an amount from 0.02 to 1.0 moles/litre and sodium carbonate in an amount from 0.02 to 1.5 moles/litre have been found to be desirable.
The reducing agents used in the present invention are soluble tertiary aminoboranes, preferably in an amount of from 0.004 to 0.020 moles/litre, or diisopropylaminoborane, preferably in an amount of from 0.002 to 0.08 moles/litre.
The tertiary amines described in U.S. Patent No.
4,255,194, namely trialkylaminoboranes having the formula R1R2R3NBH3, where R1, R2 and R3 are methyl or ethyl groups, and N-alkyl-substituted morpholinoboranes having the general formula:
where R is an alkyl group preferably having from 1 to 3 carbon atoms, but having a solubility of at least 0.004 moles/litre, are preferred.
The most preferred reducing agents are trimethylaminoborane (TMAB), preferably in an amount from 0.004 to 0.15 moles/litre; methylmorpholinoborane, preferably in an amount from 0.065 to 0.12 moles/litre; and diisopropylaminoborane, preferably in an amount from 0.0002 to 0.08 moles/litre.
For baths of the present invention maintained above 350C it is desirable to utilize a catalytic poison stabilizer. Suitable stabilizers include mercaptans, such as 6-ethoxymercaptobenzothiazole (EMBT), the preferred stabilizer; cyanohydroquinones, such as 2,3-dicyanohydroquinone; organic iodine compounds, such as iodopyridinol; alkali metal iodates; and organic compounds containing sulphur double bonded to carbon, such as 3-ethyl-3-thioxo-4-oxazolidinone or ethylaxanthic acid. Other types of compounds, especially sulphur-containing organic compounds, also stabilize the baths of the present invention.
Most of the stabilizers are effective in an amount of 1 to 5 ppm. The cyanide ion is not effective as a stabilizer, and amounts less than on ppm will stop plating altogether.
Regeneration of the bath may be accomplished by addition of a solution of a gold complex and solid reducer to the depleted bath at room temperature. The gold solution may be made by dissolving the soluble salt of tetrachloroaurate ion in a small quantity of water, adding proportionally about half as much ligand as was used in the original make up of the bath, and then heating to boiling to complex the gold. More than one complete turnover of gold in the bath has been accomplished without a reduction in plating rate or a loss of plate quality.
In the preferred method of preparation of the bath, a soluble salt of tetrachloroaurate ion is dissolved in water and a solid salt containing the inorganic ligand is added. When the resulting solution is heated to a gentle boil, the colour of the solution will change from yellow to either very light yellow or become colourless. Failure to heat the solution as described, however, will result in catastrophic bath decomposition when the reducer is added.
After cooling to room temperature, a stabilizer is preferably added to the solution of the gold complex. Thereafter an aqueous solution of aminoborane reducing agent is added and the combined solutions are stirred. The resulting bath is brought up to the desired volume, if necessary, with distilled water and thereafter filtered through a medium porosity paper to remove any undissolved material.
Copper, nickel mild steel and stainless steel can be plated in accordance with the present invention without pre-treatment (apart from optional degreasing or oxide removal by the use of, for example, a solution of concentrated hydrochloric acid). Electrolessly plated nickel and palladium, as well as gold (plated from a cyanidefree bath) can be directly plated in accordance with the present invention without pretreatment.
ABS plastic, on the other hand, may be first etched and treated with tin chlorides and palladium chloride or gold chloride solutions, as may be ceramics such as aluminium oxide. Glass may be first abraded and then treated in the same manner as ceramics. Other substrates may require sensitization procedures, as commonly known in the art.
The invention will now be illustrated by the following Examples.
Example 1
A bath was made up using preparation procedures set forth above, the bath containing KAuCI4.3H2O (2.0 g/litre), Na3PO4 12H2O (20
g/litre), 2-mercaptobenzothiazole (MBT) (1.2 mg/ml), and trimethylaminoborane (TMAB) (2.0 g/litre). The pH was about 11.9. The bath, maintained at 500C, was used to plate a palladium chloride sensitized nickel workpiece at a rate of 25 ,uin/hr (0.635 m/hr), with a plating load of 36 cm2/litre.
The resulting plate was very smooth and shiny, and the plate hardness was found to be 94 DPN using a 25 gram load.
Example 2
A bath was made up as in Example 1, the bath containing KAuCI 3H20 (2.7 g/litre), Na2CO3 (15 g/litre), MBT (10 mg/litre) and TMAB (4.0 g/litre).
The bath pH was about 10.8. Tin chloridepalladium chloride treated mildly etched glass was plated at 450C. Chemical analysis of the plate showed that it contained about 0.15% boron.
Example 3
A bath was made up as in Example 1, the bath containing KAuCI4 3H20 (2.0 g/litre), NaBO2 (10 g/litre), methylmorpholinoborate (5 g/litre) and
MBT (1.6 g/litre). The pH was adjusted to 12.6 with sodium hydroxide solution. At 600 C, the observed plating rate was 1 5 zin/hr (0.38 ym/hr) on palladium chloride sensitized nickel sheet.
Example 4
A bath was made up as in Example 1, the bath containing KAuCI4 2H20 (4.0 g/litre),
Na3PO4 1 2H20 (40 g/litre), TMAB (4.0 g/litre) and 6-ethoxy-2-mercaptobenzothiazole (EMBT) (2.0 mg/litre). Then, 50 yin (1.3 ym) of electroless nickel-phosphorous was first plated on a copper sheet, and then the workpiece was rinsed with distilled water and placed in the electroless gold bath. Plating rates of 20 to 25 ,uin/hr (0.51 to 0.635 ,um/hr) were observed at 550C.
Example 5
A bath was made up as in Example 1, the bath containing KAuCI4 2H20 (4.0 g/litre), Na3PO4.12H20 (20 g/litre), TMAB (1.0 g/litre) and 3-ethyl-2-thioxo-4-oxazolidinone (5.5 mg/litre).
At 550 C, the bath plated at 31 yin/hr (0.79 ym/hr) at a plating load at 24 cm2/litre. The plate was very smooth and shiny and adhered well to the nickel substrate.
Example 6
A bath was made up as in Example 1, the bath containing KAuCI4 2H2O (5.2 g/litre), MBT (1.2 mg/litre), NaBO2 (10 g/litre) and diisopropylaminoborane (8 g/litre). At a bath temperature of 600C, gold was plated on catalyzed nickel sheet at 1 5 juin/hr (0.38 ym/hr).
Example 7
A bath was made up as in Example 1, the bath containing KAuCI4. 2H20 (2.0 g/litre), NABO (10 g/litre), MBT (1.5 mg/litre), and TMAB (2.0 g/litre).
An ABS plastic sample was etched and catalyzed, and plated at 550C at a rate of 25 ,uin/hr (0.0635 Hm/hr).
Microhardness measurements were made with a 25 g load on electroless gold plate at least 1.5 mil (39 Mm) in thickness. The microhardness was found to be 90-100 DPN, which is slightly harder than pure gold.
Poration as determined by a standard nitric acid fume test was one por/cm2 or less at 50 yin (1.3 ilium) plate thickness over smooth, clean substrates. Rougher or improperly cleaned substrates showed greater poration.
Claims (13)
1. A bath for the electroless plating of gold upon a substrate, the bath comprising an aqueous solution of (a) gold complexed with an inorganic ligand, and (b) a secondary or tertiary aminoborane, the solution having a pH of from 8.5 to 14.
2. A bath as claimed in claim 1, wherein the inorganic ligand is selected from borate, carbonate, phosphate, pyrophosphate, o-silicate and m-silicate.
3. A bath as claimed in claim 1 or 2, wherein the gold is present in an amount of from 0.001 to 0.05 moles/litre.
4. A bath as claimed in any of claims 1 to 3, wherein the aminoborane is a secondary aminoborane, and is present in an amount of from 0.002 to 0.08 moles/litre.
5. A bath as claimed in any of claims 1 to 4, wherein the aminoborane is diisopropylaminoborane.
6. A bath as claimed in any of claims 1 to 3, wherein the aminoborane is a tertiary aminoborane, and is present in an amount of from 0.004 to 0.02 moles/litre.
7. A bath as claimed in any of claims 1, 2, 3 and 6, wherein the aminoborane is a trialkylaminoborane or an N-alkyl-substituted morpholinoborane.
8. A bath as claimed in any of claims 1 to 7, the gold being derived from a soluble salt of tetrachloroaurate ions.
9. An aqueous bath for the electroless plating of gold, comprising an aqueous solution of (a) gold complexed with an anion selected from borates, carbonates, phosphates, pyrophosphates, o-silicates and m-silicates, and (b) a tertiary aminoborane or diisopropylaminoborane in an amount of at least 0.002 moles/iitre, and the solution having a pH of from 8.5 to 14.
1 0. An aqueous bath for the electroless plating of gold, comprising (a) trivalent gold in a concentration of about 0.001 to 0.05 moles/litre; (b) an inorganic ligand selected from soluble borates, o-silicates, m-silicates, phosphates, pyrophosphates and carbonates, in an amount of from 0.02 to 6.0 moles/litre; and (c) a tertiary aminoborane having a solubility of at least 0.004 moles/litre or at least 0.002 mole/litre of diisopropylaminoborane; the bath having a pH of from 8.5 to 14.
1 A bath as claimed in any of claims 1 to 10, the aqueous solution further comprising a catalytic poison stabilizer.
12. A bath as claimed in any of claims 1 to 11, prepared by heating an aqueous solution comprising gold ions and inorganic anions so as to form a complex, by cooling the solution, and by adding a secondary or tertiary aminoborane to the solution.
13. A method of preparing an aqueous bath for the electroless plating of gold, comprising (a) preparing a solution comprising an aqueous solution of trivalent gold and adding thereto an inorganic ligand comprising a borate, phosphate, carbonate, pyrophosphate or o- or m-silicate anion; (b) heating said solution to complex said gold and ligand anion; and (c) adding to said solution after it cools a tertiary aminoborane in an amount of from 0.004 to 0.020 moles/litre or diisopropylaminoborane in an amount of from 0.002 to 0.08 mole/litre to form the plating bath.
1 4. A bath for the electroless plating of gold, prepared by a method as claimed in claim 13.
1 5. A bath as claimed in claim 1, substantially as described in any of the foregoing Examples.
1 6. A substrate provided with gold plate produced by electroless plating using a bath as claimed in any of claims 1 to 12, 14 and 15.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US34246882A | 1982-01-25 | 1982-01-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2114159A true GB2114159A (en) | 1983-08-17 |
| GB2114159B GB2114159B (en) | 1986-02-12 |
Family
ID=23341958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08232572A Expired GB2114159B (en) | 1982-01-25 | 1982-11-15 | Method and bath for the electroless plating of gold |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS602387B2 (en) |
| CA (1) | CA1182953A (en) |
| DE (1) | DE3247144C2 (en) |
| FR (1) | FR2520385B1 (en) |
| GB (1) | GB2114159B (en) |
| IT (1) | IT1160454B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830668A (en) * | 1986-11-24 | 1989-05-16 | W. C. Heraeus Gmbh | Acidic bath for electroless deposition of gold films |
| US5470381A (en) * | 1992-11-25 | 1995-11-28 | Kanto Kagaku Kabushiki Kaisha | Electroless gold plating solution |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW467770B (en) * | 2000-10-24 | 2001-12-11 | Huei-Tang Liou | Gold plating method for quartz or high alumina tube of high heat resistance and high voltage resistance, and gold-plated quartz and high alumina tube for the application of ozone generator |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52151637A (en) * | 1976-04-29 | 1977-12-16 | Trw Inc | Aqueous solution for gold plating and method of applying gold film onto nickel surface at room temperature |
| US4091128A (en) * | 1976-10-08 | 1978-05-23 | Ppg Industries, Inc. | Electroless gold plating bath |
| GB1547028A (en) * | 1976-11-19 | 1979-06-06 | Mine Safety Appliances Co | Electroless gold plating baths |
-
1982
- 1982-11-15 GB GB08232572A patent/GB2114159B/en not_active Expired
- 1982-11-23 FR FR8219596A patent/FR2520385B1/en not_active Expired
- 1982-11-29 JP JP57207768A patent/JPS602387B2/en not_active Expired
- 1982-12-21 DE DE3247144A patent/DE3247144C2/en not_active Expired
- 1982-12-23 CA CA000418444A patent/CA1182953A/en not_active Expired
-
1983
- 1983-01-21 IT IT19210/83A patent/IT1160454B/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830668A (en) * | 1986-11-24 | 1989-05-16 | W. C. Heraeus Gmbh | Acidic bath for electroless deposition of gold films |
| US5470381A (en) * | 1992-11-25 | 1995-11-28 | Kanto Kagaku Kabushiki Kaisha | Electroless gold plating solution |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3247144C2 (en) | 1985-01-10 |
| IT1160454B (en) | 1987-03-11 |
| FR2520385A1 (en) | 1983-07-29 |
| GB2114159B (en) | 1986-02-12 |
| JPS602387B2 (en) | 1985-01-21 |
| FR2520385B1 (en) | 1986-03-14 |
| CA1182953A (en) | 1985-02-26 |
| JPS58133367A (en) | 1983-08-09 |
| IT8319210A0 (en) | 1983-01-21 |
| DE3247144A1 (en) | 1983-08-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |