US3032436A - Method and composition for plating by chemical reduction - Google Patents
Method and composition for plating by chemical reduction Download PDFInfo
- Publication number
- US3032436A US3032436A US70129A US7012960A US3032436A US 3032436 A US3032436 A US 3032436A US 70129 A US70129 A US 70129A US 7012960 A US7012960 A US 7012960A US 3032436 A US3032436 A US 3032436A
- Authority
- US
- United States
- Prior art keywords
- gold
- bath
- plating
- per liter
- grams per
- 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.)
- Expired - Lifetime
Links
- 238000007747 plating Methods 0.000 title claims description 30
- 238000000034 method Methods 0.000 title claims description 29
- 239000003638 chemical reducing agent Substances 0.000 title description 17
- 239000000203 mixture Substances 0.000 title description 9
- 238000006722 reduction reaction Methods 0.000 title description 7
- XTFKWYDMKGAZKK-UHFFFAOYSA-N potassium;gold(1+);dicyanide Chemical compound [K+].[Au+].N#[C-].N#[C-] XTFKWYDMKGAZKK-UHFFFAOYSA-N 0.000 claims description 15
- 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 claims description 14
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims description 14
- YWYZEGXAUVWDED-UHFFFAOYSA-N triammonium citrate Chemical compound [NH4+].[NH4+].[NH4+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O YWYZEGXAUVWDED-UHFFFAOYSA-N 0.000 claims description 12
- 229910052709 silver Inorganic materials 0.000 claims description 7
- 239000004332 silver Substances 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 50
- 229910052737 gold Inorganic materials 0.000 description 50
- 239000010931 gold Substances 0.000 description 50
- 229910052751 metal Inorganic materials 0.000 description 17
- 239000002184 metal Substances 0.000 description 17
- 239000000243 solution Substances 0.000 description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- 238000000151 deposition Methods 0.000 description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 230000008021 deposition Effects 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 4
- 229910052783 alkali metal Inorganic materials 0.000 description 4
- 239000000908 ammonium hydroxide Substances 0.000 description 4
- 239000000470 constituent Substances 0.000 description 4
- -1 ferrous metals Chemical class 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 229910001369 Brass Inorganic materials 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000010951 brass Substances 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
- 238000009472 formulation Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- ACVYVLVWPXVTIT-UHFFFAOYSA-M phosphinate Chemical compound [O-][PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-M 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910000906 Bronze Inorganic materials 0.000 description 2
- YCKAUIGWBYGLHB-UHFFFAOYSA-M C(CC(O)(C(=O)O)CC(=O)[O-])(=O)[O-].[NH4+].[Au](C#N)(C#N)C#N.[K+] Chemical compound C(CC(O)(C(=O)O)CC(=O)[O-])(=O)[O-].[NH4+].[Au](C#N)(C#N)C#N.[K+] YCKAUIGWBYGLHB-UHFFFAOYSA-M 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 239000010974 bronze Substances 0.000 description 2
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- SDKPSXWGRWWLKR-UHFFFAOYSA-M sodium;9,10-dioxoanthracene-1-sulfonate Chemical compound [Na+].O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2S(=O)(=O)[O-] SDKPSXWGRWWLKR-UHFFFAOYSA-M 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 150000005208 1,4-dihydroxybenzenes Chemical class 0.000 description 1
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 241001156002 Anthonomus pomorum Species 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 241000982035 Sparattosyce Species 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000007933 aliphatic carboxylic acids Chemical class 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 239000013040 bath agent Substances 0.000 description 1
- 239000006172 buffering agent Substances 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical group [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 150000002344 gold compounds Chemical class 0.000 description 1
- 150000002429 hydrazines Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910021652 non-ferrous alloy Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 229910001379 sodium hypophosphite Inorganic materials 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 238000006557 surface reaction Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 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
Definitions
- Metals have heretofore been plated with gold by several known procedures, including electrolytic plating, immersion in gold salt solutions, and by reduction of gold from gold solutions. Each of these known procedures has certain disadvantages.
- Electrolytic processes require careful control of bath compositions, plating current and voltage in order to obtain bright uniform deposits, particularly on irregularly shaped objects and in addition, electrolytic processes require expensive electrical apparatus.
- One object of this invention is to provide a bath which rapidly and uniformly deposits a bright, smooth gold plate on metal articles immersed therein.
- a further object is to provide a bath which is simple to operate andwhichwill deposit thicknesses of upwards of 0.001 inch of gold as a plating on metal articles.
- Still another object is to provide a bath which will operate satisfactorily when loaded with 0.1 square inch and more of surface area to be plated per gallon of bath.
- Still another object is to provide a plating process which eliminates the need for expensive or complicated apparatus and which produces gold plating in which the gold content is at least 99% of the total plated deposit.
- the process comprises: (1) preparing a suitable complexed gold-bearing solution including one'or more: buffering agents, additives to adjust the pH of the bath, and reducing agents and (2) maintaining the bath composition and temperature within definite ranges to produce a desirable rate of deposition of a gold plating with desired characteristics.
- the process is applicable to the plating of gold on both ferrous and non-ferrous metals, but since the coating is most advantageously accomplished on nickel, copper or silver to which metals the gold plating adheres best, it is preferred to provide an intermediate layer of nickel, copper or silver on metallic or non-metallic articles which it is desired to coat with gold.
- gold may be plated directly on iron, steel and other ferrous alloys as well as silver, brass, bronze or other non-ferrous alloys.
- the plating baths of this invention provide a gold plating on metal articles or metal coated non-metallic articles immersed therein by chemical reduction and do not require any impressed potential as in electrolytic plating.
- the preferred gold bearing constituent is potassium gold cyanide which is commercially available in sutficient purity for the present processes.
- the second essential constituent of our electroless plating bath is a reducing agent for the gold compound dissolved.
- a reducing agent for the gold compound dissolved.
- reducing agents any of a wide variety of reducing agents may be employed, hydrazine hydrate is the reducing agent preferred by us.
- Other reducing agents which have been used to satisfactorily deposit gold on metal surfaces include other hydrazine derivatives, alkali metal borohydrides, glucose and other sugars, hydroquinones, alkali metal hypophosphites and the like.
- a buffer in our bath is ammonium citrate, but other alkali metal salts of acetic, citric or other similar carboxylic acids may also be used to this end.
- the bath may contain a relatively weak acid or base added to produce the desired pH.
- Ammonia, ammonium hydroxide, citric acid and other acids and bases have been found suitable.
- a plating bath was prepared consisting of the following:
- Ammonium hydroxide was added to adjust the pH.
- the amount of gold deposited has been found to vary with changes in temperature, concentration of reducing agent and the pH of the bath.
- compositions of the plating baths, of Example 1 indicated below have been operated at temperatures ranging from 70 C. to 100 C.:
- the above baths operated satisfactorily at temperatures from 70 C. up to 100 C. and at pH values ranging from 3 to 12.
- Optimum gold plating was obtained at pHs from 7 to 7.5 and the preferred bath temperature range was found to be from 92 C. to 95 C.
- Example 1 Grams per liter Potassium gold cyanide Ammonium citrate 8-0 Hydrazine .0001 Potassium gold cyanide 3 Ammonium citrate 90 Hydroquinone .001 Potassium gold cyanide 3 Ammonium citrate 90 Sodium hypophosphite 8
- the formulation described in Example 1 produced the best-appearing gold and was much more stable over longer periods of time than those in Examples 2-4.
- the bath should be replenished by addition of reducing agent and pH adjusting material in small amounts.
- a gold bearing material must also be added to maintain the gold concentration in the range indicated and to thereby maintain the bath effectiveness.
- a method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in a bath containing from 0.2 to 10 grams per liter of potassium gold cyanide, from 10 to 200 grams per liter of ammonium citrate, and from 0.0001 to 1.0 gram per liter of hydrazine hydrate; and in further adding a small quantity of pH adjusting substance, sufficient to adjust the pH of the bath to a desired value between 3 and 12 and in adding constantly to the bath a solution of hydrazine hydrate, and small quantities of the potassium gold cyanide to replenish the gold content of the bath and in maintaining the bath at a temperature between 70 C. and 100 C.
- the method of gold plating metallic surfaces which consists in immersing an article consisting of metallic constituents selected from the group consisting of iron, steel, silver, copper, brass, br0 nze and nickel in a bath containing from .2 to 10 grams per liter potassium gold cyanide, from 10 to 200 grams per liter ammonium citrate, and from 0.0001 to 1.0 gram per liter hydrazine hydrate; and in adding to the bath a gold replenisher solution of potassium gold cyanide and ammonium citrate sufiicient to maintain the gold content of the bath and a solution of hydrazine hydrate sufiicient to continue deposition of the gold, while maintaining the pH of the bath between 3 and 12 and the temperature of the bath between 70 C. and 100 C.
- a method of gold plating metallic surfaces which consists in immersing an article consisting of metallic constituents selected from the group consisting of iron, steel, silver, copper, brass, bronze and nickel in a bath containing from 0.2 to 10 grams per liter potassium gold cyanide, from 10 to 200 grams per liter ammonium citrate, and from 0.0001 to 1.0 gram per liter hydrazine hydrate; and in adding ammonium hydroxide to adjust the pH of the bath to a value of between 3-12 while maintaining the bath at a temperature of between 70-100 C. and in replenishing constantly the bath forming chemicals and the pH adjusting ammonium hydroxide to maintain the pH at a constant value.
- the method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in a bath containing 3 grams per liter potassium gold cyanide, grams per liter ammonium citrate, and 0.0002 gram per liter hydrazine hydrate, maintaining the bath at a temperature of approximately 92 to 94 C. and at a pH of between 7-7.5.
- a method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in an aqueous bath containing from 0.2 to 10 grams per liter of potassium gold cyanide, a buffer consisting of an alkali metal salt of an aliphatic carboxylic acid and a pH adjusting substance in sufiicient amount to provide a pH in the bath of between 3 and 12, and from 0.001 to 1.0 gram per liter of hydrazine hydrate reducing agent, and in maintaining the metallic surface to be gold plated in the bath while the bath is maintained at a temperature between 70 C. and C.
- a plating bath for depositing gold on a metallic substrate wherein the bath comprises: 0.2 to 10 grams per liter of potassium gold cyanide 10 to 200 grams per liter of ammonium citrate 0.0001 to 1 grams per liter of hydrazine hydrate 5 balance water.
- hydroxide in an amount sufiicient to provide a pH between 3 and 12.
Description
United States Patent 9 3,032,436 METHOD AND COMPOSITION FOR PLATING BY CHEMICAL REDUCTION Ernest L. Gostin, Boonton, and Stewart D. Swan, Coytesville, N.J., assignors to Metal Processing Co., Inc., Cedar Grove, N.J., a corporation of New Jersey No Drawing. Filed Nov. 18, 1960, Ser. No. 70,129 9 Claims. (Cl. 117-71) This invention relates to plating by chemical reduction and more particularly to a method and bath for plating metallic articles and metallic coated articles with a tenacious relatively thick smooth bright gold coating and without the use of electricity by simple immersion of the article in a bath of suitable composition.
Metals have heretofore been plated with gold by several known procedures, including electrolytic plating, immersion in gold salt solutions, and by reduction of gold from gold solutions. Each of these known procedures has certain disadvantages.
Electrolytic processes require careful control of bath compositions, plating current and voltage in order to obtain bright uniform deposits, particularly on irregularly shaped objects and in addition, electrolytic processes require expensive electrical apparatus.
Formulas and methods for using common immersion plates, including gold are described in the Metal Finishing Guide Book, 27th edition (1959), page 469 et seq. These are used when extremely thin plating thicknesses are de sired, e.-g. those a few millionths of an inch in thickness. In these processes no reducing agents are used and because of the relative nobility of gold as compared with most common metals, articles of copper, copper alloys or zinc may be plated by immersion in a bath containing a gold salt in solution. In the process, the deposition of metals depends entirely on replacement, that is, an exchange occurs in which a slight amount of metal from the surface of the article passes into the solution and an equivalent amount of gold plates out from the plating solution and onto the article. This is a surface reaction and does not proceed after the surface is covered with the metal in solution. Hence the process operates only for a brief interval after which the gold deposited on the surface effectively prevents the base metal from entering the solution, and hence the plating ceases and is extremely thin.
Another procedure which has been employed, particularly in the manufacture of gold mirrors has involved the use of solutions of reducing agents to react with the gold in a gold solution and to deposit elemental gold from the solution. These also are very thin.
Since the work of Brenner and Riddell at the U.S. Bureau of Standards describing the deposition of cobalt and nickel through chemical reduction in a hypophosphite bath, there has been a growing demand for the deposition of gold by a chemical reduction process. Specifically there exists a need for an effective system for the coating of electronic components having intricate or deep-seated configurations, and particularly for an improved process for depositing gold in coating thicknesses exceeding those obtainable by the electroless hypophosphite process taught in Roux Patent 1,207,218. The life of such hypophosphite baths has been found to be limited due primarily to the phosphite and a phosphate build-up and auto-degeneration of the reducing agent.
One object of this invention is to provide a bath which rapidly and uniformly deposits a bright, smooth gold plate on metal articles immersed therein.
A further object is to provide a bath which is simple to operate andwhichwill deposit thicknesses of upwards of 0.001 inch of gold as a plating on metal articles.
"ice
Still another object is to provide a bath which will operate satisfactorily when loaded with 0.1 square inch and more of surface area to be plated per gallon of bath.
Still another object is to provide a plating process which eliminates the need for expensive or complicated apparatus and which produces gold plating in which the gold content is at least 99% of the total plated deposit.
These and other objects of the invention will be apparent from the following description and the appended claims.
In general the process comprises: (1) preparing a suitable complexed gold-bearing solution including one'or more: buffering agents, additives to adjust the pH of the bath, and reducing agents and (2) maintaining the bath composition and temperature within definite ranges to produce a desirable rate of deposition of a gold plating with desired characteristics. The process is applicable to the plating of gold on both ferrous and non-ferrous metals, but since the coating is most advantageously accomplished on nickel, copper or silver to which metals the gold plating adheres best, it is preferred to provide an intermediate layer of nickel, copper or silver on metallic or non-metallic articles which it is desired to coat with gold. However, gold may be plated directly on iron, steel and other ferrous alloys as well as silver, brass, bronze or other non-ferrous alloys.
As noted above, the plating baths of this invention provide a gold plating on metal articles or metal coated non-metallic articles immersed therein by chemical reduction and do not require any impressed potential as in electrolytic plating.
In the plating baths of this invention, the preferred gold bearing constituent is potassium gold cyanide which is commercially available in sutficient purity for the present processes.
The second essential constituent of our electroless plating bath is a reducing agent for the gold compound dissolved. Although any of a wide variety of reducing agents may be employed, hydrazine hydrate is the reducing agent preferred by us. Other reducing agents which have been used to satisfactorily deposit gold on metal surfaces include other hydrazine derivatives, alkali metal borohydrides, glucose and other sugars, hydroquinones, alkali metal hypophosphites and the like.
The presence of a buffer has also been found to be desirable because deposits obtained from nearly neutral baths appear to be superior to deposits obtained from very acid or very alkaline baths. A preferred buffer in our bath is ammonium citrate, but other alkali metal salts of acetic, citric or other similar carboxylic acids may also be used to this end.
Finally the bath may contain a relatively weak acid or base added to produce the desired pH. Ammonia, ammonium hydroxide, citric acid and other acids and bases have been found suitable. 1
The following examples are intended to further illus trate this invention and are not to be taken as lirnitative.
EXAMPLE 1 A plating bath was prepared consisting of the following:
Ingredient: Concentration (grams per liter) Potassium gold cyanide Ammonium citrate 9O Hydrazine hydrate .0002
Water, balance to make 1 liter.
Ammonium hydroxide was added to adjust the pH.
The amount of gold deposited has been found to vary with changes in temperature, concentration of reducing agent and the pH of the bath. Y
The compositions of the plating baths, of Example 1 indicated below have been operated at temperatures ranging from 70 C. to 100 C.:
Ingredient: Concentration (grams per liter) Potassium gold cyanide 0.210 Ammonium citrate 10-200 Hydrazine hydrate 0.0001-1 NH OH, to give pH between 3 and 12.
The above baths operated satisfactorily at temperatures from 70 C. up to 100 C. and at pH values ranging from 3 to 12. Optimum gold plating was obtained at pHs from 7 to 7.5 and the preferred bath temperature range was found to be from 92 C. to 95 C.
EXAMPLES 2-4 Three other specific formulations which plated gold on metal substrates in accordance with this invention had the following formulations:
Grams per liter Potassium gold cyanide Ammonium citrate 8-0 Hydrazine .0001 Potassium gold cyanide 3 Ammonium citrate 90 Hydroquinone .001 Potassium gold cyanide 3 Ammonium citrate 90 Sodium hypophosphite 8 The formulation described in Example 1 produced the best-appearing gold and was much more stable over longer periods of time than those in Examples 2-4.
The gold deposition was continuous as evidenced by an increase in the weight of gold deposited on test panels left in the specific bath of Example 1 for longer intervals Deposits having considerable thicknesses of about 0.001 inch of gold have been obtained by leaving the articles in the bath for a sufiicient length of time as shown by the following data in Table 2:
Table 2 Panel A (92-94 0.) Panel B (92-95" C.)
Time (1118.) Total Thiek- Time (hrs) Total Thickness (in) ness (in) From time to time, and preferably continuously, the bath should be replenished by addition of reducing agent and pH adjusting material in small amounts. For continued operation, a gold bearing material must also be added to maintain the gold concentration in the range indicated and to thereby maintain the bath effectiveness.
Each of the above described baths has been successfully employed to deposit gold on resistors and other electronic components, of metal or of ceramic, plastic or other non-metallic materials, coated with an intermediate metallic layer.
In accordance with the patent statutes we have described the invention and the best method of practicing the same. The above description is intended to be illustrative and we do not desire to be limited to the order of steps of such process as herein recited, or to the specific proportions of such parts employed therein, or to the precise ingredients named therein, as it is evident that each of these ingredients has a considerable range of equivalents, and as it is also evident that the order and proportions of the process may be carried out without departing from its scope and purposes.
What is claimed as new is as follows:
1. A method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in a bath containing from 0.2 to 10 grams per liter of potassium gold cyanide, from 10 to 200 grams per liter of ammonium citrate, and from 0.0001 to 1.0 gram per liter of hydrazine hydrate; and in further adding a small quantity of pH adjusting substance, sufficient to adjust the pH of the bath to a desired value between 3 and 12 and in adding constantly to the bath a solution of hydrazine hydrate, and small quantities of the potassium gold cyanide to replenish the gold content of the bath and in maintaining the bath at a temperature between 70 C. and 100 C.
2. The method of gold plating metallic surfaces as claimed in claim 1, wherein the article to be gold plated is first coated with a coating of a metal selected from the group consisting of copper, silver and nickel, before being immersed into the bath.
3. The method of gold plating metallic surfaces which consists in immersing an article consisting of metallic constituents selected from the group consisting of iron, steel, silver, copper, brass, br0 nze and nickel in a bath containing from .2 to 10 grams per liter potassium gold cyanide, from 10 to 200 grams per liter ammonium citrate, and from 0.0001 to 1.0 gram per liter hydrazine hydrate; and in adding to the bath a gold replenisher solution of potassium gold cyanide and ammonium citrate sufiicient to maintain the gold content of the bath and a solution of hydrazine hydrate sufiicient to continue deposition of the gold, while maintaining the pH of the bath between 3 and 12 and the temperature of the bath between 70 C. and 100 C.
4. A method of gold plating metallic surfaces which consists in immersing an article consisting of metallic constituents selected from the group consisting of iron, steel, silver, copper, brass, bronze and nickel in a bath containing from 0.2 to 10 grams per liter potassium gold cyanide, from 10 to 200 grams per liter ammonium citrate, and from 0.0001 to 1.0 gram per liter hydrazine hydrate; and in adding ammonium hydroxide to adjust the pH of the bath to a value of between 3-12 while maintaining the bath at a temperature of between 70-100 C. and in replenishing constantly the bath forming chemicals and the pH adjusting ammonium hydroxide to maintain the pH at a constant value.
5. The method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in a bath containing 3 grams per liter potassium gold cyanide, grams per liter ammonium citrate, and 0.0002 gram per liter hydrazine hydrate, maintaining the bath at a temperature of approximately 92 to 94 C. and at a pH of between 7-7.5.
6. A method of gold plating metallic surfaces which consists in immersing an article having a metallic surface in an aqueous bath containing from 0.2 to 10 grams per liter of potassium gold cyanide, a buffer consisting of an alkali metal salt of an aliphatic carboxylic acid and a pH adjusting substance in sufiicient amount to provide a pH in the bath of between 3 and 12, and from 0.001 to 1.0 gram per liter of hydrazine hydrate reducing agent, and in maintaining the metallic surface to be gold plated in the bath while the bath is maintained at a temperature between 70 C. and C.
7. A plating bath for depositing gold on a metallic substrate wherein the bath comprises: 0.2 to 10 grams per liter of potassium gold cyanide 10 to 200 grams per liter of ammonium citrate 0.0001 to 1 grams per liter of hydrazine hydrate 5 balance water.
8. The plating bath of 01am 7 wherein the proportlons 2,915,406
are:
3 grams per liter potassium gold cyanide 2 7 1 1 90 grams per liter ammonium citrate and 0.0002 grams per liter hydrazine hydrate.
9. The bath of claim 7 including in addition ammonium 1,681
hydroxide in an amount sufiicient to provide a pH between 3 and 12.
References Cited in the file of this patent UNITED STATES PATENTS Roux Dec. 5, 1916 McNally May 27, 1958 Rhoda Dec. 1, 1959 Crishal et al. J an. 24, 1961 Brookshire Mar. 21, 1961 FOREIGN PATENTS Great Britain 1855
Claims (2)
1. A MEHTOD OF GOLD PLATING METALLIC SURFACES WHICH CONSISTS IN IMMERSING AN ARTICLE HAVING A METALLIC SURFACE IN A BOTH CONTAINING FROM 0.2 TO 10 GRAMS PER LITER OF POTASSIUM GOLD CYANIDE, FROM 10 TO 200 GRAMS PER LITER OF AMMONIUM CITRATE, AND FROM 0.0001 TO 1.0 GRAM PER LITER OF HYDRAZINE HYDRATE; AND IN FURTHER ADDING A SMALL QUANTITY OF PH ADJUSTING SUBSTANCE, SUFFICIENT TO ADJUST THE PH OF THE BATH TO A DESIRED VALUE BETWEEN 3 AND 12 AND IN ADDING CONSTANTLY TO THE BATH A SOLUTION OF HYDRAZINE HYDRATE, AND SMALL QUANTITIES OF THE POTASSIUM GOLD CYANIDE TO REPLENISH THE GOLD CONTENT OF THE BATH AND IN MAINTAINING THE BATH AT A TEMPERATURE BETWEEN 70*C. AND 100*C.
2. THE METHOD OF GOLD PLATING METALLIC SURFACES AS CLAIMED IN CLAIM 1, WHEREIN THE ARTICLE TO BE GOLD PLATED IS FIRST COATED WITH A COATING OF A METAL SELECTED FROM THE GROUP CONSISTING OF COPPER, SILVER AND NICKEL, BEFORE BEING IMMERSED INTO THE BATH.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US70129A US3032436A (en) | 1960-11-18 | 1960-11-18 | Method and composition for plating by chemical reduction |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US70129A US3032436A (en) | 1960-11-18 | 1960-11-18 | Method and composition for plating by chemical reduction |
Publications (1)
Publication Number | Publication Date |
---|---|
US3032436A true US3032436A (en) | 1962-05-01 |
Family
ID=22093306
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US70129A Expired - Lifetime US3032436A (en) | 1960-11-18 | 1960-11-18 | Method and composition for plating by chemical reduction |
Country Status (1)
Country | Link |
---|---|
US (1) | US3032436A (en) |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3198659A (en) * | 1962-04-09 | 1965-08-03 | Lockheed Aircraft Corp | Thin nickel coatings |
US3214292A (en) * | 1962-09-12 | 1965-10-26 | Western Electric Co | Gold plating |
US3230098A (en) * | 1962-10-09 | 1966-01-18 | Engelhard Ind Inc | Immersion plating with noble metals |
US3266929A (en) * | 1962-12-17 | 1966-08-16 | Shipley Co | Gold plating by immersion |
US3300328A (en) * | 1963-11-12 | 1967-01-24 | Clevite Corp | Electroless plating of gold |
DE1281221B (en) * | 1962-09-12 | 1968-10-24 | Western Electric Co | Process for the electroless deposition of gold coatings on metallic and semiconducting surfaces through ion exchange |
US3468676A (en) * | 1963-09-09 | 1969-09-23 | Photocircuits Corp | Electroless gold plating |
US3470074A (en) * | 1964-08-18 | 1969-09-30 | Siemag Siegener Masch Bau | Depositing zinc coatings |
US3515571A (en) * | 1963-07-02 | 1970-06-02 | Lockheed Aircraft Corp | Deposition of gold films |
US3862850A (en) * | 1973-06-08 | 1975-01-28 | Ceramic Systems | Electroless gold plating on refractory metals |
US3992211A (en) * | 1968-07-15 | 1976-11-16 | Trans-Metals Corporation | Electroless plating composition |
US4091128A (en) * | 1976-10-08 | 1978-05-23 | Ppg Industries, Inc. | Electroless gold plating bath |
DE3029785A1 (en) * | 1980-08-04 | 1982-03-25 | Schering Ag, 1000 Berlin Und 4619 Bergkamen | ACID GOLD BATH FOR ELECTRIC DEPOSIT OF GOLD |
DE3614090C1 (en) * | 1986-04-25 | 1987-04-30 | Heraeus Gmbh W C | Bath for the currentless deposition of gold layers |
DE3640028C1 (en) * | 1986-11-24 | 1987-10-01 | Heraeus Gmbh W C | Acid bath for the electroless deposition of gold layers |
US4832743A (en) * | 1986-12-19 | 1989-05-23 | Lamerie, N.V. | Gold plating solutions, creams and baths |
US4863766A (en) * | 1986-09-02 | 1989-09-05 | General Electric Company | Electroless gold plating composition and method for plating |
WO2000025136A1 (en) * | 1998-10-27 | 2000-05-04 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
EP1026285A2 (en) * | 1999-01-27 | 2000-08-09 | Shipley Company LLC | Electroless gold plating solution and process |
EP1209958A2 (en) * | 2000-11-24 | 2002-05-29 | Millennium Gate Technology Co., Ltd. | Laminated structure for electronic equipment and method of electroless gold plating |
US20060083850A1 (en) * | 2004-10-18 | 2006-04-20 | Enthone Inc. | Cobalt and nickel electroless plating in microelectronic devices |
US20060211136A1 (en) * | 1999-10-27 | 2006-09-21 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
US7589047B1 (en) * | 2006-06-08 | 2009-09-15 | Los Alamos National Security, Llc | Composite materials and method of making |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1207218A (en) * | 1914-01-19 | 1916-12-05 | L Aluminium Francais Soc | Process of producing metallic deposits. |
US2836515A (en) * | 1953-04-30 | 1958-05-27 | Westinghouse Electric Corp | Gold immersion solution for treating silver and method of applying same |
US2915406A (en) * | 1958-03-03 | 1959-12-01 | Int Nickel Co | Palladium plating by chemical reduction |
US2969295A (en) * | 1958-05-05 | 1961-01-24 | Pacific Semiconductors Inc | Chemical gold plating |
US2976181A (en) * | 1957-12-17 | 1961-03-21 | Hughes Aircraft Co | Method of gold plating by chemical reduction |
-
1960
- 1960-11-18 US US70129A patent/US3032436A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1207218A (en) * | 1914-01-19 | 1916-12-05 | L Aluminium Francais Soc | Process of producing metallic deposits. |
US2836515A (en) * | 1953-04-30 | 1958-05-27 | Westinghouse Electric Corp | Gold immersion solution for treating silver and method of applying same |
US2976181A (en) * | 1957-12-17 | 1961-03-21 | Hughes Aircraft Co | Method of gold plating by chemical reduction |
US2915406A (en) * | 1958-03-03 | 1959-12-01 | Int Nickel Co | Palladium plating by chemical reduction |
US2969295A (en) * | 1958-05-05 | 1961-01-24 | Pacific Semiconductors Inc | Chemical gold plating |
Cited By (35)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3198659A (en) * | 1962-04-09 | 1965-08-03 | Lockheed Aircraft Corp | Thin nickel coatings |
US3214292A (en) * | 1962-09-12 | 1965-10-26 | Western Electric Co | Gold plating |
DE1281221B (en) * | 1962-09-12 | 1968-10-24 | Western Electric Co | Process for the electroless deposition of gold coatings on metallic and semiconducting surfaces through ion exchange |
US3230098A (en) * | 1962-10-09 | 1966-01-18 | Engelhard Ind Inc | Immersion plating with noble metals |
US3266929A (en) * | 1962-12-17 | 1966-08-16 | Shipley Co | Gold plating by immersion |
US3515571A (en) * | 1963-07-02 | 1970-06-02 | Lockheed Aircraft Corp | Deposition of gold films |
DE1521357B1 (en) * | 1963-07-02 | 1970-06-04 | Lockheed Aircraft Corp | Process for the electroless deposition of a gold layer |
US3468676A (en) * | 1963-09-09 | 1969-09-23 | Photocircuits Corp | Electroless gold plating |
US3300328A (en) * | 1963-11-12 | 1967-01-24 | Clevite Corp | Electroless plating of gold |
US3470074A (en) * | 1964-08-18 | 1969-09-30 | Siemag Siegener Masch Bau | Depositing zinc coatings |
US3992211A (en) * | 1968-07-15 | 1976-11-16 | Trans-Metals Corporation | Electroless plating composition |
US3862850A (en) * | 1973-06-08 | 1975-01-28 | Ceramic Systems | Electroless gold plating on refractory metals |
US4091128A (en) * | 1976-10-08 | 1978-05-23 | Ppg Industries, Inc. | Electroless gold plating bath |
DE3029785A1 (en) * | 1980-08-04 | 1982-03-25 | Schering Ag, 1000 Berlin Und 4619 Bergkamen | ACID GOLD BATH FOR ELECTRIC DEPOSIT OF GOLD |
US4352690A (en) * | 1980-08-04 | 1982-10-05 | Schering Aktiengesellschaft | Acid gold bath for the electroless deposition of gold |
DE3614090C1 (en) * | 1986-04-25 | 1987-04-30 | Heraeus Gmbh W C | Bath for the currentless deposition of gold layers |
US4863766A (en) * | 1986-09-02 | 1989-09-05 | General Electric Company | Electroless gold plating composition and method for plating |
DE3640028C1 (en) * | 1986-11-24 | 1987-10-01 | Heraeus Gmbh W C | Acid bath for the electroless deposition of gold layers |
US4830668A (en) * | 1986-11-24 | 1989-05-16 | W. C. Heraeus Gmbh | Acidic bath for electroless deposition of gold films |
US4832743A (en) * | 1986-12-19 | 1989-05-23 | Lamerie, N.V. | Gold plating solutions, creams and baths |
US20040033626A1 (en) * | 1998-10-27 | 2004-02-19 | Erez Braun | Method for gold deposition |
WO2000025136A1 (en) * | 1998-10-27 | 2000-05-04 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
US7851149B2 (en) | 1998-10-27 | 2010-12-14 | Erez Braun | Method for gold deposition |
US7056748B1 (en) | 1998-10-27 | 2006-06-06 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
KR100712261B1 (en) * | 1999-01-27 | 2007-04-26 | 롬 앤드 하스 일렉트로닉 머트어리얼즈, 엘.엘.씨 | Electroless gold plating solution and process |
US6383269B1 (en) | 1999-01-27 | 2002-05-07 | Shipley Company, L.L.C. | Electroless gold plating solution and process |
EP1026285A3 (en) * | 1999-01-27 | 2001-12-12 | Shipley Company LLC | Electroless gold plating solution and process |
EP1026285A2 (en) * | 1999-01-27 | 2000-08-09 | Shipley Company LLC | Electroless gold plating solution and process |
US20060211136A1 (en) * | 1999-10-27 | 2006-09-21 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
US7364920B2 (en) | 1999-10-27 | 2008-04-29 | Technion Research And Development Foundation Ltd. | Method for gold deposition |
EP1209958A2 (en) * | 2000-11-24 | 2002-05-29 | Millennium Gate Technology Co., Ltd. | Laminated structure for electronic equipment and method of electroless gold plating |
EP1209958A3 (en) * | 2000-11-24 | 2004-04-21 | Millennium Gate Technology Co., Ltd. | Laminated structure for electronic equipment and method of electroless gold plating |
US20060083850A1 (en) * | 2004-10-18 | 2006-04-20 | Enthone Inc. | Cobalt and nickel electroless plating in microelectronic devices |
US7332193B2 (en) | 2004-10-18 | 2008-02-19 | Enthone, Inc. | Cobalt and nickel electroless plating in microelectronic devices |
US7589047B1 (en) * | 2006-06-08 | 2009-09-15 | Los Alamos National Security, Llc | Composite materials and method of making |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3032436A (en) | Method and composition for plating by chemical reduction | |
Barker | Electroless deposition of metals | |
US4600609A (en) | Method and composition for electroless nickel deposition | |
US5614003A (en) | Method for producing electroless polyalloys | |
US4374876A (en) | Process for the immersion deposition of gold | |
US5322553A (en) | Electroless silver plating composition | |
US4567066A (en) | Electroless nickel plating of aluminum | |
US3870526A (en) | Electroless deposition of copper and copper-tin alloys | |
US6183546B1 (en) | Coating compositions containing nickel and boron | |
US4242180A (en) | Ammonia free palladium electroplating bath using aminoacetic acid | |
US3230098A (en) | Immersion plating with noble metals | |
US4780342A (en) | Electroless nickel plating composition and method for its preparation and use | |
US3024134A (en) | Nickel chemical reduction plating bath and method of using same | |
US6020021A (en) | Method for depositing electroless nickel phosphorus alloys | |
US5435838A (en) | Immersion plating of tin-bismuth solder | |
US4913787A (en) | Gold plating bath and method | |
CA1188458A (en) | Electroless gold plating | |
US20070175359A1 (en) | Electroless gold plating solution and method | |
US3468676A (en) | Electroless gold plating | |
US2976180A (en) | Method of silver plating by chemical reduction | |
US3697296A (en) | Electroless gold plating bath and process | |
US3661596A (en) | Stabilized, chemical nickel plating bath | |
US3667972A (en) | Chemical nickel plating baths | |
EP0359784A1 (en) | Stabilized electroless baths for wear-resistant metal coatings | |
US3674516A (en) | Electroless codeposition of nickel alloys |