US3149057A - Acid gold plating - Google Patents

Acid gold plating Download PDF

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Publication number
US3149057A
US3149057A US808913A US80891359A US3149057A US 3149057 A US3149057 A US 3149057A US 808913 A US808913 A US 808913A US 80891359 A US80891359 A US 80891359A US 3149057 A US3149057 A US 3149057A
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US
United States
Prior art keywords
gold
solution
acid
cobalt
chelate
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
Application number
US808913A
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English (en)
Inventor
Edward A Parker
James A Powers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Technic Inc
Original Assignee
Technic Inc
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Filing date
Publication date
Application filed by Technic Inc filed Critical Technic Inc
Priority to US808913A priority Critical patent/US3149057A/en
Priority to GB37258/59A priority patent/GB880656A/en
Priority to DET17650A priority patent/DE1213697B/de
Application granted granted Critical
Publication of US3149057A publication Critical patent/US3149057A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/62—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of gold

Definitions

  • the present invention relates to the electrolytic deposition of gold on surfaces and more particularly to the electrodeposition of gold and gold alloys from solutions of the same onto objects to develop a gold or gold alloy appearance.
  • Gold baths of this conventional type containing free alkali cyanide are never allowed to operate on the acid side, because of the formation and elimination from the bath of the extremely toxic hydrogen cyanide gas.
  • An additional chemical reason for maintaining alkaline baths resides in the fact that where an alkali metal aurocyanide solution is contacted with a strong mineral acid, one cyanide radical is displaced from the aurocyanide complex anion and there separates from the solution insoluble aurous cyanide.
  • Such 24 karat baths must be operated hot and are usually limited to rather low current densities. It is also diflicult to obtain bright deposits in heavy thicknesses, i.e. greater than .000050". It, therefore, has been common practice in the prior art to add to such a bath certain soluble metal salts which are co-deposited with the gold in order to impart certain qualities to the plate such as color, hardness, wear resistance, etc.
  • cobalt (II) chelate of ethylenediamine tetra-acetic acid, or other chelating agent giving with cobalt (II) a chelate having a stability constant of the same order of magnitude, to an alkali metal aurocyanide at a relatively low pH will produce a bright, smooth electrodeposit of gold which is better than 99.8% pure.
  • the amount of cobalt chelate employed in the solution of gold to effect this result may vary from 1 gram per liter up to 50 grams per liter.
  • Gold alloy plates may also be obtained from this bath by incorporating into the bath certain metal salts, complexes, or chelates, because such other metals plate out with the gold.
  • certain metal salts, complexes, or chelates may be men tioned antimony tartrate, nickel or cadmium ethylenediamine tetra-acetic acid.
  • Similar compounds of indium, zinc, copper, iron may be used to obtain alloy plates.
  • a primary object of the present invention to provide an aqueous acid solution from which gold may be electrodeposited in which the harmful consequences of the formation of free hydrogen cyanide are eliminated.
  • the present invention accordingly, comprises a bath from which gold may be electrolytically deposited, the bath essentially consisting of an aqueous solution of an alkali metal aurocyanide, with or without additional a1 loying salts, the cobalt chelate of ethylenediarnine tetraacetic acid, or a cobalt che-late of a chelating agent having a stability constant of about the same order of magnitude, and at least one buffer material to maintain the pH between 3.0 and 4.5 during the deposition of the gold from the solution.
  • the maintenance of the pH value between 3.0 and 4.5 is most easily accomplished by incorporating into the bath 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 electro-deposition of the gold or its alloy.
  • 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 electro-deposition of the gold or its alloy.
  • 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 buffer region in the specified pH range, when properly neutralized with the appropriate amount of base.
  • the acids most useful are the soluble aliphatic acids containing 2 to 8 C atoms, and also may carry hydroxyl groups in functional relationship to the carboxylic groups.
  • Typical useful acids are citric, citraconic, itaconic, lactic, gluconic, glutaric and glycollic.
  • the electrolytic deposition can be carried out using insoluble anodes such as platinum, gold, stainless steel or carbon, and replenishment of the gold and its alloying components can be accomplished during plating to maintain these materials at their original concentrations as the bath is used.
  • the ratio of anode surface area to cathode surface area should be most preferably not less than 1:1.
  • the temperature of the bath should be held within the limits of 55 to F. during the electrodeposition. It has been found that mechanical agitation of the bath, such as with a stirrer, serves to facilitate clean, smooth deposition, and at the same time permits the use of higher current densities without smutting the plated surface.
  • the electrical tension between the anodes and the wares is held between 2 and 4 volts.
  • Example I Into an amount of water suificient to form 1 liter of solution is dissolved:
  • ethylenediamine The pH is then adjusted with either phosphoric acid or potassium hydroxide to a value near 4.0, but no lower than 3.0 nor higher than 4.5.
  • Example i V Into an amount of water suflicient to form 1 liter of solution is dissolved:
  • the preferre gold plating formula of this invention includes a very substantial molar excess of the organic acid over the amount of gold present. Generally it may be said that at least two moles of the acid or mixture of acids being used per mole of gold is a preferred range. Within said range the gold is held in complex form, hydrogen cyanide is not released, optimum pH in the range of 3-5 is achieved and gold plate of mirror-bright finish is consistently produced.
  • Typical ethylenediaminetriacetic acid compounds which are useful chelating agents for holding the cobalt in the form of a complex of the requisite of stability to accomplish the results of the invention are ethylenediaminetetraacetic acid, hydroxyethyl ethylenediaminetriacetic acid, hydroxypropyl ethylenediaminetriacetic acid, ethylenediaminediacetic acid and the like. It seems that the essential element of structure in the compound is a spaced acetic acid moiety which will form a cobalt com plex of the desired level of stability.
  • a bright gold plating bath consisting essentially of a Water solution of gold cyanide
  • the improvement which comprises incorporating and maintaining in said solution a cobaltous chelate of an ethylenediamine acetic acid compound, the cobaltous chelate having a stability such that it is not electrodeposited with the gold under plating conditions, the solution being buffered at a pH level in the range from about 3 to about 5, the chelate being such that cobalt is not deposited under plating conditions.
  • a composition suitable for formulation of acid gold plating solutions comprising a mixture of potassium gold cyanide and potassium cobaltous ethylenediamine tetraacetate, the ratio of the two being about 1-50 parts of the gold by weight to as much as 25 parts of cobalt by weight.
  • An aqueous gold plating solution in accordance with claim 2 consisting essentially of:
  • An aqueous gold plating solution in accordance with claim 2 consisting essentially of:
  • An aqueous gold plating solution in accordance with claim 2 consisting essentially of:
  • indium as the indium chelate of ethylenediaminetetraacetic acid, and sufiicient citric acid and potassium hydroxide to maintain the pH in the range from 3 to 4.5.
  • An aqueous gold plating solution in accordance with claim 2 consisting essentially of:
  • An aqueous gold plating solution in accordance with claim 2 consisting essentially of:
  • cobalt as potassium cobaltous chelate of ethylenediaminetetraacetic acid, and sufficient monopotassium phosphate, citric acid and potassium hydroxide to maintain the pH of said solution at a level in the rangefrom 3 to 4.
  • the improvement comprising forming a water solution of gold cyanide and maintaining in said solution a minor amount of cobalt of valence II as a chelate of an ethylenediamine acetic acid compound, said solution containing buifering ingredients suitable to maintain the pH of the solution in the range from about 3 to about 5, so that at current densities up to 100 amperes per square foot'a bright gold plate is achieved at temperatures up to 100 F. without deposition of cobalt.
  • the improvement comprising formulating said gold as the auro (I) cyanide in an aqueous medium wherein the pH of said medium is maintained in the range from about 3 to about 5, in the presence of organic acids selected from the group consisting of acetic, citric, citratonic, itaconic, glutaric, lactic succinic and gluconic acidsand mixtures thereof, and also in the presence of a cobaltous chelate of a compound selected from the group consisting of ethylenediaminetetraacetic acid, hydroxyethyl ethylenediamine triacetic' acid, hydroxypropylethylenediaminetriacetic acid, and ethylenediaminediacetic'acid.
  • the improvement which comprises maintaining the gold in solution as the auro (I) cyanide at a pH in the range from about 3 to about 5 in the presence of an alloying metal for simultaneous electrodepo'sition with gold, the improvement comprising acetic acid, hydroxyethyl ethylenediamine triacetic acid,
  • acobaltous chelate selected from the group consisting of ethylenediaminetetrahydroxypropylethylenediaminetriacetic acid, and ethylenediaminediacetic acid.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
US808913A 1959-04-27 1959-04-27 Acid gold plating Expired - Lifetime US3149057A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US808913A US3149057A (en) 1959-04-27 1959-04-27 Acid gold plating
GB37258/59A GB880656A (en) 1959-04-27 1959-11-03 Acid gold plating
DET17650A DE1213697B (de) 1959-04-27 1959-12-23 Saures cyanidisches Bad, Mischung zur Herstellung des Bades und Verfahren zum galvanischen Abscheiden von glaenzenden Gold- oder Goldlegierungsueberzuegen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US808913A US3149057A (en) 1959-04-27 1959-04-27 Acid gold plating

Publications (1)

Publication Number Publication Date
US3149057A true US3149057A (en) 1964-09-15

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US808913A Expired - Lifetime US3149057A (en) 1959-04-27 1959-04-27 Acid gold plating

Country Status (3)

Country Link
US (1) US3149057A (de)
DE (1) DE1213697B (de)
GB (1) GB880656A (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303112A (en) * 1963-10-28 1967-02-07 American Chem & Refining Co Acidic gold cyanide electroplating bath and process
US3423295A (en) * 1966-02-23 1969-01-21 Engelhard Ind Inc Gold plating
US3460953A (en) * 1966-05-27 1969-08-12 Pennsalt Chemicals Corp Process for depositing brasslike coatings and composition therefor
US3475292A (en) * 1966-02-10 1969-10-28 Technic Gold plating bath and process
US3902977A (en) * 1973-12-13 1975-09-02 Engelhard Min & Chem Gold plating solutions and method
US4076598A (en) * 1976-11-17 1978-02-28 Amp Incorporated Method, electrolyte and additive for electroplating a cobalt brightened gold alloy
DE2831756A1 (de) * 1977-07-20 1979-02-01 Technic Cobalt- und nickelorganophosphonate als glanzbildner fuer die elektroplattierung
DE3244092A1 (de) * 1981-12-14 1983-06-23 American Chemical & Refining Co., Inc., 06720 Waterbury, Conn. Waessriges bad zur galvanischen abscheidung von gold und verfahren zur galvanischen abscheidung von hartgold unter seiner verwendung
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
WO1988009401A1 (en) * 1987-05-29 1988-12-01 Vanguard Research Associates, Inc. Electrolyte solution and process for gold electroplating
US5575900A (en) * 1995-07-03 1996-11-19 Antelman Technologies Ltd. Gold plating solutions

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3562120A (en) * 1966-09-07 1971-02-09 Sel Rex Corp Plating of smooth,semibright gold deposits

Citations (3)

* Cited by examiner, † Cited by third party
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

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE731102C (de) * 1941-12-13 1943-02-03 Dr Herbert Brintzinger Verfahren zur Erzeugung metallischer UEberzuege
NL103564C (de) * 1956-09-08

Patent Citations (3)

* Cited by examiner, † Cited by third party
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 (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303112A (en) * 1963-10-28 1967-02-07 American Chem & Refining Co Acidic gold cyanide electroplating bath and process
US3475292A (en) * 1966-02-10 1969-10-28 Technic Gold plating bath and process
US3423295A (en) * 1966-02-23 1969-01-21 Engelhard Ind Inc Gold plating
US3460953A (en) * 1966-05-27 1969-08-12 Pennsalt Chemicals Corp Process for depositing brasslike coatings and composition therefor
US3902977A (en) * 1973-12-13 1975-09-02 Engelhard Min & Chem Gold plating solutions and method
US4076598A (en) * 1976-11-17 1978-02-28 Amp Incorporated Method, electrolyte and additive for electroplating a cobalt brightened gold alloy
DE2831756A1 (de) * 1977-07-20 1979-02-01 Technic Cobalt- und nickelorganophosphonate als glanzbildner fuer die elektroplattierung
US4186064A (en) * 1977-07-20 1980-01-29 Technic, Inc. Method and electrolyte for electrodeposition of bright gold and gold alloys
DE3244092A1 (de) * 1981-12-14 1983-06-23 American Chemical & Refining Co., Inc., 06720 Waterbury, Conn. Waessriges bad zur galvanischen abscheidung von gold und verfahren zur galvanischen abscheidung von hartgold unter seiner verwendung
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
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
US5575900A (en) * 1995-07-03 1996-11-19 Antelman Technologies Ltd. Gold plating solutions

Also Published As

Publication number Publication date
GB880656A (en) 1961-10-25
DE1213697B (de) 1966-03-31

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