US3149058A - Bright gold plating process - Google Patents
Bright gold plating process Download PDFInfo
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- US3149058A US3149058A US863111A US86311159A US3149058A US 3149058 A US3149058 A US 3149058A US 863111 A US863111 A US 863111A US 86311159 A US86311159 A US 86311159A US 3149058 A US3149058 A US 3149058A
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- gold
- nickel
- acid
- chelate
- solution
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- 238000000034 method Methods 0.000 title claims description 12
- 238000007747 plating Methods 0.000 title claims description 9
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title description 39
- 229910052737 gold Inorganic materials 0.000 title description 38
- 239000010931 gold Substances 0.000 title description 38
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 44
- 229910052759 nickel Inorganic materials 0.000 claims description 22
- 239000013522 chelant Substances 0.000 claims description 19
- 239000002253 acid Substances 0.000 claims description 14
- 230000008021 deposition Effects 0.000 claims description 7
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 claims description 6
- 150000007524 organic acids Chemical class 0.000 claims description 6
- 229910052783 alkali metal Inorganic materials 0.000 claims description 4
- 230000000717 retained effect Effects 0.000 claims description 4
- 150000001340 alkali metals Chemical class 0.000 claims description 3
- IZLAVFWQHMDDGK-UHFFFAOYSA-N gold(1+);cyanide Chemical compound [Au+].N#[C-] IZLAVFWQHMDDGK-UHFFFAOYSA-N 0.000 claims description 3
- 239000002738 chelating agent Substances 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 19
- 238000000151 deposition Methods 0.000 description 8
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 239000003513 alkali Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910001020 Au alloy Inorganic materials 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 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- FJAAKDGALOFQSO-UHFFFAOYSA-N [K].[Ni] Chemical compound [K].[Ni] FJAAKDGALOFQSO-UHFFFAOYSA-N 0.000 description 4
- 150000007513 acids Chemical class 0.000 description 4
- 238000004070 electrodeposition Methods 0.000 description 4
- 239000003353 gold alloy Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 239000000872 buffer Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000002659 electrodeposit Substances 0.000 description 3
- XTFKWYDMKGAZKK-UHFFFAOYSA-N potassium;gold(1+);dicyanide Chemical compound [K+].[Au+].N#[C-].N#[C-] XTFKWYDMKGAZKK-UHFFFAOYSA-N 0.000 description 3
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- IFQUWYZCAGRUJN-UHFFFAOYSA-N ethylenediaminediacetic acid Chemical compound OC(=O)CNCCNCC(O)=O IFQUWYZCAGRUJN-UHFFFAOYSA-N 0.000 description 2
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 2
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 2
- 235000019796 monopotassium phosphate Nutrition 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 2
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- -1 valence II) Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BDDLHHRCDSJVKV-UHFFFAOYSA-N 7028-40-2 Chemical compound CC(O)=O.CC(O)=O.CC(O)=O.CC(O)=O BDDLHHRCDSJVKV-UHFFFAOYSA-N 0.000 description 1
- 239000004135 Bone phosphate Substances 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- 238000007547 Knoop hardness test Methods 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 241000220010 Rhode Species 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- OBITVHZFHDIQGH-UHFFFAOYSA-N [Au].[K]C#N Chemical compound [Au].[K]C#N OBITVHZFHDIQGH-UHFFFAOYSA-N 0.000 description 1
- ZFVMPHOLEJVJPJ-UHFFFAOYSA-N acetic acid;azane Chemical compound N.N.CC(O)=O.CC(O)=O.CC(O)=O ZFVMPHOLEJVJPJ-UHFFFAOYSA-N 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910000318 alkali metal phosphate Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000002650 laminated plastic Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- NKCCODPFBDGPRJ-UHFFFAOYSA-N nitridocarbon(1+) Chemical compound N#[C+] NKCCODPFBDGPRJ-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- 239000001508 potassium citrate Substances 0.000 description 1
- 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 1
- 238000002360 preparation method Methods 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 235000015870 tripotassium citrate Nutrition 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/48—Electroplating: Baths therefor from solutions of gold
Definitions
- the present invention relates to gold plated products and to a process for electrodepositing gold and gold alloys and more particularly to the electrolytic preparation of gold and gold alloy plates presenting hard, heat-resistant, smooth, mirror-bright surfaces.
- free alkali cyanide alkali metal hydroxides and carbonates, and, almost always, a di-basic or tri-basic alkali metal phosphate.
- Gold and gold alloy baths have always been operated on the alkaline side, however, for reasons which are well founded. For instance, most gold baths contain free cyanide as an aid to throwing power. Consequently, these baths must remain alkaline or the extremely toxic hydrogen cyanide gas would be generated in situ and released from the bath. Still another reason is that soluble metal aurocyanide solutions are unstable with respect to strong mineral acids, as one cyanide radical is displaced from the complex and there separates from solution insoluble gold cyanide.
- nickel (II) nickel of valence l1
- chelate of the aminopolycarboxylic acid type having a stability constant of the order of magnitude of about 10, i.e., stability of the order of that of nickel ll nitrilo triacetic acid
- an alkali metal aurocyanide solution at a relatively low pH will produce an electrodeposit of gold, which is more than 99.8% pure gold, i.e. 24K gold.
- the amount of nickel chelate employed in the solution may range up to grams of nickel per liter.
- Gold content of the bath is preferably in the range from about 2 grams per liter to about saturation, with about 8 grams per liter preferred.
- the plates so obtained are of high reflectivity, increased hardness generally at least 120 Knoop, and exhibit better wear resistance, and tarnish resistance than gold deposited from conventional aurocyanide baths. That is, with respect to tarnish, the gold plate we obtain is so hard and heat resistant that it can withstand temperatures of 300 C. for periods of two hours and more without discoloration.
- the present invention accordingly, essentially consists of an improved plate or article, characterized by its I bright, smooth, hard, pure gold plate and a bath from which such gold may be electrolytically deposited to form the article, the bath comprising an aqueous solution of an alkali metal aurocyanide with or without additional alloying metal compounds, the nickel (Il) (nickel, valence II), chelate of an appropriate amino polycarboxylic acid, preferably one selected from the group consisting of nitrilo triacetic acid, ethylene diarnine tetraacetic acid, fl-hy droxyethylethylene diamine triacetic acid, and ethylene diamine diacetic acid, and at least one buffer material to maintain the pH between 3.5 and 5.5 during the deposition of the gold from the solution. While generally we use a single chelate of this group, it is perfectly appropriate to use mixtures of the nickel chelates.
- the electrolytic deposition can be carried out using insoluble anodes such as platinum, gold, stainless steel, or carbon. Replenishment of the gold and its alloying components can be effected by any convenient means, such as ampere-minutes, as is well known in the art.
- the ratio of anode to cathode surface area, while not critical, should be most preferably at least 1:1.
- the temperature of the bath should be held within the limits of 60 to F. during the electrodeposition as a preferred operating range. It has been found that mechanical agitation of the bath, such as with a stirrenserves to facilitate clean, smooth deposition, and at the same time permits the use of higher current densities without smutting the pleated surface.
- Q9 electrical tension between the anode and the wares will usually lie between 2 and 6 volts.
- Example 1 Into an amount of water sufiicient to form one liter of solution is dissolved:
- Example ll Into an amount of water suflicient to form one liter of solution is added:
- the plate obtained on any basis metal, whether over barrier layers or not, is mirror bright, hard, tarnish resistant at temperatures of the order of 300 C. for 2-3 hours. That is, in terms of this process, the basis metal is that which is in direct contact with the gold layer, whether the basis thus in contact be massive piece or mere layer.
- Knoop hardness tests of samples of the plate made according to Examples 1 and II consistently showed values of 120-160, for plates as thin as could be measured up to 2-3 mils (i.e. 0002-0003 inch).
- Heating tests of the samples showed they remained mirror bright, in thickness approaching a flash (0.000003 inch) up to 1 and 2 thousandths inch after 2 and 3 hours at 300 C.
- Specimens of heavy plates i.e., those up to 2-3 thousandths remained mirror bright at temperatures of 400-500" C. even after 4 hours. This, of course, emphasizes the unusual property of these gold plates when compared with other so called bright gold plates which will tarnish at 200 C. in 10 minutes.
- any of the nickel chelates mentioned or any combination of the chelates as a mixture may be used.
- a method of electrodepositing bright, hard gold in substantially pure form which comprises electrolyzing a solution comprising a weak, stable, organic acid in amount sufficient to provide a pH of 3-5, goldas an alkali metal gold cyanide, and a nickel (H) chelate of an aminopolycarboxylic acid chelating agent, said nickel being in a substantially non-ionized form, and being retained in solution without significant deposition under plating conditions.
- nickel chelate is the 1:1 chelate of ethylenediarninetetraacetic acid.
- nickel chelate is the 1:1 chelate of hydroxyethylethylenediarninetriacetic acid.
- nickel chelate is a mixture of the 1:1 chelate of nitrilotriacetic acid and ethylenediaminetetraacetic acid.
- nickel chelate is a mixture of the 1:1 chelate of ethylenediaminetetraacetic acid and nitrilotriacetic acid.
- An electrolyte for depositing bright,- heat resistant substantially pure gold coatings on surfaces comprising a weak, stable, organic acid in amount sufiicient to provide a pH of 3-5, gold as a gold cyanide, a nickel (II) chelate of a compound selected from the group consisting of: nitrilotriacetic acid, ethylenediaminetetraacetic acid, fi-hydroxyethylethylenediaminetriacetic acid, ethylenediaminediacetic acid and mixtures thereof, said nickel being in a substantially non-ionized form, retained in solution Without significant deposition under plating conditions.
- An electrolyte for depositing bright, heat resistant, gold coatings of substantially 24K fineness on surfaces comprising an organic acid in amount suflicient to provide a pH of 3-5, about 2 grams per liter to saturation of gold as potassium gold cyanide, about 1-10 grams per liter of nickel (II) as nickel chelate of an aminopolycarboxylic acid selected from the group consisting of: nitrilotriacetic acid, ethylenediaminetetraacetic acid, ,B-hydroxyethylethylenediaminetriacetic acid, ethylenediarninediacetic acid and mixtures thereof, said nickel being in a substantially non-ionized form and retained in solution without significant deposition under plating conditions.
- an organic acid in amount suflicient to provide a pH of 3-5, about 2 grams per liter to saturation of gold as potassium gold cyanide, about 1-10 grams per liter of nickel (II) as nickel chelate of an aminopolycarboxylic acid selected from the group consisting of: n
Description
United States Patent 3,14%,053 BRIGHT GGLD PLATHJG PROCESS Edward A. Parker, Qranston, and James A. Powers, East Providence, 5.2.1., assignors to Technic, ind, Cranston, R1,, a corporation of Rhode Island No Drawing. Filed Dec. 31, 1959, Ser. No. 863,111 8 Claims. (Cl. 204-46) The present invention relates to gold plated products and to a process for electrodepositing gold and gold alloys and more particularly to the electrolytic preparation of gold and gold alloy plates presenting hard, heat-resistant, smooth, mirror-bright surfaces.
For many years, it has been common practice in the electrodeposition of gold to use a bath consisting of potassium gold cyanide, along with other alkali or alkali producing materials. These ancillary products were included in the bath for various reasons, such as to increase conductivity; to obtain good throwing power; to maintain color; or to buffer the bath on the alkaline side.
Among these products may be mentioned free alkali cyanide, alkali metal hydroxides and carbonates, and, almost always, a di-basic or tri-basic alkali metal phosphate.
These gold baths must be operated at elevated temperatures, and are usually limited to rather low current densities. It is also difficult to obtain bright deposits in heavy thickness, i.e. greater than 0.000050 inch, which will be hard, heat-resistant, bright, etc. 7
Gold and gold alloy baths have always been operated on the alkaline side, however, for reasons which are well founded. For instance, most gold baths contain free cyanide as an aid to throwing power. Consequently, these baths must remain alkaline or the extremely toxic hydrogen cyanide gas would be generated in situ and released from the bath. Still another reason is that soluble metal aurocyanide solutions are unstable with respect to strong mineral acids, as one cyanide radical is displaced from the complex and there separates from solution insoluble gold cyanide.
In recent years, the manufacture of printed circuits has created an expanding demand for a gold plating process which would utilize solutions not detrimental to the plastic laminate used as the base for the printed circuit. Heat and alkali are two of the most severe agents in the deterioration of this material.
We have found that the addition of a nickel (II) (nickel of valence l1), chelate of the aminopolycarboxylic acid type having a stability constant of the order of magnitude of about 10, i.e., stability of the order of that of nickel ll nitrilo triacetic acid, to an alkali metal aurocyanide solution at a relatively low pH will produce an electrodeposit of gold, which is more than 99.8% pure gold, i.e. 24K gold. The amount of nickel chelate employed in the solution may range up to grams of nickel per liter. Gold content of the bath is preferably in the range from about 2 grams per liter to about saturation, with about 8 grams per liter preferred.
However, we prefer to operate in the region of 1-5 grams of nickel per liter. Heavy deposits of gold may also be obtained which are brilliant in character. The speed of plating is also increased so that current densities of 60 amperes per square foot are possible. Furthermore, the plates so obtained are of high reflectivity, increased hardness generally at least 120 Knoop, and exhibit better wear resistance, and tarnish resistance than gold deposited from conventional aurocyanide baths. That is, with respect to tarnish, the gold plate we obtain is so hard and heat resistant that it can withstand temperatures of 300 C. for periods of two hours and more without discoloration.
Accordingly, it is a primary object of the present invention to provide a bath from which gold may be electrodeposited without the harmful effects of alkali and alkali producing materials.
It is a further object of the present invention to provide a solution from which gold may electrodeposit to produce an electroplate of high reflectivity and which will provide the mirror image of an object placed before it.
It is a further object of the present invention to provide a solution from which gold may be electrodeposited in a smooth fashion at room temperature.
It is a further object of the present invention to provide a solution from which gold may be electrodeposited to give bright, lustrous, thick plates at fast plating speeds, which plates will show a high Knoop hardness, at least about 120, and temperature resistance of about 300 C. for two hours.
Other objects and advantages of the invention will in part be obvious and in part appear hereinafter.
The present invention, accordingly, essentially consists of an improved plate or article, characterized by its I bright, smooth, hard, pure gold plate and a bath from which such gold may be electrolytically deposited to form the article, the bath comprising an aqueous solution of an alkali metal aurocyanide with or without additional alloying metal compounds, the nickel (Il) (nickel, valence II), chelate of an appropriate amino polycarboxylic acid, preferably one selected from the group consisting of nitrilo triacetic acid, ethylene diarnine tetraacetic acid, fl-hy droxyethylethylene diamine triacetic acid, and ethylene diamine diacetic acid, and at least one buffer material to maintain the pH between 3.5 and 5.5 during the deposition of the gold from the solution. While generally we use a single chelate of this group, it is perfectly appropriate to use mixtures of the nickel chelates.
Since the brightening action of the nickel (II) chelate has been found to be a function of pI-Lit is essential that this parameter be controlled. The maintennace of the pH value of the plating bath between 3.5 and 5.5 is most easily accomplished by incorporation into the bath of salts of moderately strong organic acids whose acid dissociation constants are of such a nature that they serve as buffers in restricting the pH of the solution to limits as defined during the electrodeposition of the gold or its alloy. Among these substances may be listed, as representative, certain organic acids which have at least one ionization constant of such a value as to create a buifer range in the specified pH range, when properly neutralized with the appropirate amount of base.
In general, the acids most useful are the aliphatic acids containing 2 to 8 carbon atoms, and also may carry hy droXyl groups in functional relationship to the carboXylic groups. Typical useful acids are acetic, glycollic, lactic, citric, gluconic, tartaric, kojic.
This list, while not all inclusive of the substances which may be employed, is indicative of the general kinds of acid compounds which have been found to be useful. It is also possible to use mixtures of the acids, provided the pH of the final gold bath lies in the range of 3.5 to 5.5.
The electrolytic deposition can be carried out using insoluble anodes such as platinum, gold, stainless steel, or carbon. Replenishment of the gold and its alloying components can be effected by any convenient means, such as ampere-minutes, as is well known in the art. The ratio of anode to cathode surface area, while not critical, should be most preferably at least 1:1. The temperature of the bath should be held within the limits of 60 to F. during the electrodeposition as a preferred operating range. It has been found that mechanical agitation of the bath, such as with a stirrenserves to facilitate clean, smooth deposition, and at the same time permits the use of higher current densities without smutting the pleated surface. The
. Q9 electrical tension between the anode and the wares will usually lie between 2 and 6 volts.
The following examples are typical of the types of solutions from which hardplates having the properties indicated may be detained;
Example 1 Into an amount of water sufiicient to form one liter of solution is dissolved:
8 grams potassium gold cyanide 30 grams monopotassium phosphate 35 grams tri-potassium citrate 25 grams citric acid I 3.0 grams nickel as nickel (II), N,N'-ethylenediaminediacetate The pH of this solution may be adjusted to a value between 3.2 and 4.4 with'either phosphoric acid or potassium hydroxide. The electrodeposition of gold is then accomplished in the conventional manner. The bath temperature may lie from 70 F. to 120 F. The plate ob tained on brass, or other basis metal, with or without barrier layers of other plated metals, is hard, mirror bright, and tarnish resistant at temperatures of the order of 300 C. for two to three hours.
Example ll Into an amount of water suflicient to form one liter of solution is added:
12 grams of potassium gold (I) cyanide 60 grams acetic acid and potassium acetate 30 grams monopotassium phosphate 3 gramsnickel as potassium nickel (ll) nitrilotriacetate The pH should be adjusted to a value between 3.0 and 5.0 with phosphoric acid or potassium hydroxide. Thick, bright, lustrous electrodeposits of substantially pure 24K gold are obtained from this bath at current densities up to 60 amperes per square foot. Current efficiencies of 60% are also realized.
The plate obtained on any basis metal, whether over barrier layers or not, is mirror bright, hard, tarnish resistant at temperatures of the order of 300 C. for 2-3 hours. That is, in terms of this process, the basis metal is that which is in direct contact with the gold layer, whether the basis thus in contact be massive piece or mere layer.
Samples of gold plate, plated under conditions of EX- arnples I and II, were analyzed spectrographically by an independent laboratory and the following results reported:
Percent Gold 99.78 Nickel 0.18
By spectrographic analysis:
Silver 0.007 Cobalt 0.005 Copper 0.01 Iron 0.02 Manganese 0.001 Silicon 0.001
Knoop hardness tests of samples of the plate made according to Examples 1 and II consistently showed values of 120-160, for plates as thin as could be measured up to 2-3 mils (i.e. 0002-0003 inch).
Heating tests of the samples showed they remained mirror bright, in thickness approaching a flash (0.000003 inch) up to 1 and 2 thousandths inch after 2 and 3 hours at 300 C. Specimens of heavy plates, i.e., those up to 2-3 thousandths remained mirror bright at temperatures of 400-500" C. even after 4 hours. This, of course, emphasizes the unusual property of these gold plates when compared with other so called bright gold plates which will tarnish at 200 C. in 10 minutes.
For formulating other solutions in accordance with these examples, any of the nickel chelates mentioned or any combination of the chelates as a mixture may be used.
Though the invention has been described with reference to only a few examples, it is to be understood that variants thereof may be developed without departing from its spirit or scope.
We claim:
1. A method of electrodepositing bright, hard gold in substantially pure form which comprises electrolyzing a solution comprising a weak, stable, organic acid in amount sufficient to provide a pH of 3-5, goldas an alkali metal gold cyanide, and a nickel (H) chelate of an aminopolycarboxylic acid chelating agent, said nickel being in a substantially non-ionized form, and being retained in solution without significant deposition under plating conditions.
2. A method as claimed in claim 1, in which the nickel chelate is the 1:1 chelate of ethylenediarninetetraacetic acid.
3. A method as claimed in claim 1, in which the nickel chelate is the 1:1 chelate of nitrilotriacetic acid.
4. A method as claimed in claim 1, in which the nickel chelate is the 1:1 chelate of hydroxyethylethylenediarninetriacetic acid.
5. A method as claimed in claim 1, in which the nickel chelate is a mixture of the 1:1 chelate of nitrilotriacetic acid and ethylenediaminetetraacetic acid.
6. A method as claimed in claim 1, in which the nickel chelate is a mixture of the 1:1 chelate of ethylenediaminetetraacetic acid and nitrilotriacetic acid.
7. An electrolyte for depositing bright,- heat resistant substantially pure gold coatings on surfaces comprising a weak, stable, organic acid in amount sufiicient to provide a pH of 3-5, gold as a gold cyanide, a nickel (II) chelate of a compound selected from the group consisting of: nitrilotriacetic acid, ethylenediaminetetraacetic acid, fi-hydroxyethylethylenediaminetriacetic acid, ethylenediaminediacetic acid and mixtures thereof, said nickel being in a substantially non-ionized form, retained in solution Without significant deposition under plating conditions.
8. An electrolyte for depositing bright, heat resistant, gold coatings of substantially 24K fineness on surfaces comprising an organic acid in amount suflicient to provide a pH of 3-5, about 2 grams per liter to saturation of gold as potassium gold cyanide, about 1-10 grams per liter of nickel (II) as nickel chelate of an aminopolycarboxylic acid selected from the group consisting of: nitrilotriacetic acid, ethylenediaminetetraacetic acid, ,B-hydroxyethylethylenediaminetriacetic acid, ethylenediarninediacetic acid and mixtures thereof, said nickel being in a substantially non-ionized form and retained in solution without significant deposition under plating conditions.
References Cited in the file of this patent UNITED STATES PATENTS 2,724,687 Spreter et al. Nov. 22, 1955 2,905,601 Rinker et al. Sept. 22, 1959 2,967,135 ()strow et al. Jan. 3, 1961
Claims (1)
1. A METHOD OF ELECTRODEPOSITING BRIGNT, HARD GOLD IN SUBSTANTIALLY PURE FORM WHICH COMPRISES ELECTROLYZING A SOLUTION COMPRISING A WEAK, STABLE, ORGANIC ACID IN AMOUNT SUFFICIENT TO PROVIDE A PH OF 3-5, GOLD AS AN ALKALI METAL GOLD CYANIDE, AND A NICKEL (II) CHELATE OF AN AMINOPOLYCARBOXYLIC ACID CHELATING AGENT, SAID NICKEL BEING IN A SUBSTANTIALLY NON-IONIZED FORM, AND BEING RETAINED IN SOLUTION WITHOUT SIGNIFICANT DEPOSITION UNDER PLATING CONDITIONS.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US863111A US3149058A (en) | 1959-12-31 | 1959-12-31 | Bright gold plating process |
GB38961/60A GB921960A (en) | 1959-12-31 | 1960-11-14 | Improvements in or relating to electrodepositing bright hard gold |
DET19317A DE1222348B (en) | 1959-12-31 | 1960-11-23 | Galvanic gold or gold alloy bath |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US863111A US3149058A (en) | 1959-12-31 | 1959-12-31 | Bright gold plating process |
Publications (1)
Publication Number | Publication Date |
---|---|
US3149058A true US3149058A (en) | 1964-09-15 |
Family
ID=25340283
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US863111A Expired - Lifetime US3149058A (en) | 1959-12-31 | 1959-12-31 | Bright gold plating process |
Country Status (3)
Country | Link |
---|---|
US (1) | US3149058A (en) |
DE (1) | DE1222348B (en) |
GB (1) | GB921960A (en) |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3284175A (en) * | 1964-03-09 | 1966-11-08 | Neville S Spence | Gold coated steel article |
US3427231A (en) * | 1965-07-21 | 1969-02-11 | Litton Systems Inc | Method of electroplating and electroforming gold in an ultrasonic field |
US3460953A (en) * | 1966-05-27 | 1969-08-12 | Pennsalt Chemicals Corp | Process for depositing brasslike coatings and composition therefor |
US3669852A (en) * | 1969-10-23 | 1972-06-13 | Bell Telephone Labor Inc | Electroplating gold |
US3893896A (en) * | 1973-07-02 | 1975-07-08 | Handy & Harman | Gold plating bath and process |
US3902977A (en) * | 1973-12-13 | 1975-09-02 | Engelhard Min & Chem | Gold plating solutions and method |
US3929595A (en) * | 1973-11-07 | 1975-12-30 | Degussa | Electrolytic burnished gold bath with higher rate of deposition |
US4076598A (en) * | 1976-11-17 | 1978-02-28 | Amp Incorporated | Method, electrolyte and additive for electroplating a cobalt brightened gold alloy |
US4093349A (en) * | 1976-10-27 | 1978-06-06 | Northrop Corporation | High reflectivity laser mirrors |
DE2831756A1 (en) * | 1977-07-20 | 1979-02-01 | Technic | COBALT AND NICKEL ORGANOPHOSPHONATES AS GLOSS FORMS FOR ELECTROPLATING |
US4168371A (en) * | 1977-02-04 | 1979-09-18 | Westvaco Corporation | Process for making lignin gels in bead form |
DE3244092A1 (en) * | 1981-12-14 | 1983-06-23 | American Chemical & Refining Co., Inc., 06720 Waterbury, Conn. | AQUEOUS BATH FOR GALVANIC DEPOSITION OF GOLD AND METHOD FOR GALVANIC DEPOSIT OF HARD GOLD USING ITS USE |
US4670107A (en) * | 1986-03-05 | 1987-06-02 | Vanguard Research Associates, Inc. | Electrolyte solution and process for high speed gold plating |
US4744871A (en) * | 1986-09-25 | 1988-05-17 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
US4755264A (en) * | 1987-05-29 | 1988-07-05 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
CN105506684A (en) * | 2016-02-19 | 2016-04-20 | 苏州市华婷特种电镀有限公司 | Electroplating solution for obtaining coating of gold |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2724687A (en) * | 1952-05-08 | 1955-11-22 | Spreter Victor | Baths for the deposit of gold alloys by electroplating |
US2905601A (en) * | 1957-08-13 | 1959-09-22 | Sel Rex Corp | Electroplating bright gold |
US2967135A (en) * | 1960-06-08 | 1961-01-03 | Barnet D Ostrow | Electroplating baths for hard bright gold deposits |
-
1959
- 1959-12-31 US US863111A patent/US3149058A/en not_active Expired - Lifetime
-
1960
- 1960-11-14 GB GB38961/60A patent/GB921960A/en not_active Expired
- 1960-11-23 DE DET19317A patent/DE1222348B/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2724687A (en) * | 1952-05-08 | 1955-11-22 | Spreter Victor | Baths for the deposit of gold alloys by electroplating |
US2905601A (en) * | 1957-08-13 | 1959-09-22 | Sel Rex Corp | Electroplating bright gold |
US2967135A (en) * | 1960-06-08 | 1961-01-03 | Barnet D Ostrow | Electroplating baths for hard bright gold deposits |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3284175A (en) * | 1964-03-09 | 1966-11-08 | Neville S Spence | Gold coated steel article |
US3427231A (en) * | 1965-07-21 | 1969-02-11 | Litton Systems Inc | Method of electroplating and electroforming gold in an ultrasonic field |
US3460953A (en) * | 1966-05-27 | 1969-08-12 | Pennsalt Chemicals Corp | Process for depositing brasslike coatings and composition therefor |
US3669852A (en) * | 1969-10-23 | 1972-06-13 | Bell Telephone Labor Inc | Electroplating gold |
US3893896A (en) * | 1973-07-02 | 1975-07-08 | Handy & Harman | Gold plating bath and process |
US3929595A (en) * | 1973-11-07 | 1975-12-30 | Degussa | Electrolytic burnished gold bath with higher rate of deposition |
US3902977A (en) * | 1973-12-13 | 1975-09-02 | Engelhard Min & Chem | Gold plating solutions and method |
US4093349A (en) * | 1976-10-27 | 1978-06-06 | Northrop Corporation | High reflectivity laser mirrors |
US4076598A (en) * | 1976-11-17 | 1978-02-28 | Amp Incorporated | Method, electrolyte and additive for electroplating a cobalt brightened gold alloy |
US4168371A (en) * | 1977-02-04 | 1979-09-18 | Westvaco Corporation | Process for making lignin gels in bead form |
DE2831756A1 (en) * | 1977-07-20 | 1979-02-01 | Technic | COBALT AND NICKEL ORGANOPHOSPHONATES AS GLOSS FORMS FOR ELECTROPLATING |
DE3244092A1 (en) * | 1981-12-14 | 1983-06-23 | American Chemical & Refining Co., Inc., 06720 Waterbury, Conn. | AQUEOUS BATH FOR GALVANIC DEPOSITION OF GOLD AND METHOD FOR GALVANIC DEPOSIT OF HARD GOLD USING ITS USE |
US4396471A (en) * | 1981-12-14 | 1983-08-02 | American Chemical & Refining Company, Inc. | Gold plating bath and method using maleic anhydride polymer chelate |
US4670107A (en) * | 1986-03-05 | 1987-06-02 | Vanguard Research Associates, Inc. | Electrolyte solution and process for high speed gold plating |
US4744871A (en) * | 1986-09-25 | 1988-05-17 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
US4755264A (en) * | 1987-05-29 | 1988-07-05 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
WO1988009401A1 (en) * | 1987-05-29 | 1988-12-01 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
WO1988009834A1 (en) * | 1987-06-01 | 1988-12-15 | Vanguard Research Associates, Inc. | Electrolyte solution and process for gold electroplating |
CN105506684A (en) * | 2016-02-19 | 2016-04-20 | 苏州市华婷特种电镀有限公司 | Electroplating solution for obtaining coating of gold |
Also Published As
Publication number | Publication date |
---|---|
GB921960A (en) | 1963-03-27 |
DE1222348B (en) | 1966-08-04 |
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