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US3238112A - Electroplating of metals using mercapto-metal complex salts - Google Patents

Electroplating of metals using mercapto-metal complex salts Download PDF

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US3238112A
US3238112A US207401A US20740162A US3238112A US 3238112 A US3238112 A US 3238112A US 207401 A US207401 A US 207401A US 20740162 A US20740162 A US 20740162A US 3238112 A US3238112 A US 3238112A
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metals
electroplating
mercapto
grams
solution
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US207401A
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John H Haslam
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EIDP Inc
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EI Du Pont de Nemours and Co
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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00Electroplating: Baths therefor
    • C25D3/02Electroplating: Baths therefor from solutions

Definitions

  • plating baths containing mercapto compounds have a number of advantages not possessed by conventional plating baths. For example, the need for using such highly toxic substances as cyanide in the baths is eliminated.
  • the baths give high efiiciency, both at the anode and at the cathode. They can be used at high pH levels, with their attendant advantages.
  • These baths have excellent throwing power, give a high quality plate, and have good conductivity. They also permit the use of copper and tin in their lower valence states, thereby saving plating current.
  • the mercapto compounds which can be used according to this invention are those of the formula where R is hydrogen, COOH, an alkyl radical containing from 1 to 4 carbon atoms, or a hydroyalkyl radical containing from 1 to 5 carbon atoms;
  • R is hydrogen, COOH, a hydroxyalkyl radical containing from 1 to 4 carbon atoms, or an alkyl radical containing from 1 to 4 carbon atoms;
  • n 1 or 2.
  • Z-mercaptoethanol Z-mercaptopropanol l-mercaptopropanol-Z Z-mercaptobutanol 2-mercaptobutanol-3 l-thioglycerol 2 thioglycerol a-Thiosorbitol Mercaptoacetic acid Z-mercaptosuccinic acid Mercaptoethylamine
  • the metals which can be electrically deposited according to this invention are copper, tin, silver, gold, cadmium and zinc. Alloys of these metals, such as brass, can also be deposited. These metals can be deposited on such other metals as steel, copper and brass.
  • the electroplating bath is prepared by dissolving a conventional amount of a salt of the metal to be deposited in an aqueous solution of a mercapto compound which has been previously brought to pH l011 with a stoichiometric amount of sodium or potassium hydroxide.
  • the mercapto compound should ordinarily be present at a concentration of from 2 to moles per mole of the metal to be deposited.
  • the metals to be deposited are naturally present as salts with the mercapto compound.
  • Excess sodium or potassium hydroxide in the bath generally improves plate quality and increases the conductivity of the bath.
  • Conventional brightening 3,238,112 Patented Mar. 1, 1966 agents, such as Rochelle salts or sodium hydroxyacetate and other additives, can also be added if desired.
  • the plating is then carried out with conventional electr oplating equipment, using ordinary electroplating techmques.
  • Example 1 A solution of 45 grams of SnC1 -2H O, milliliters of water and 10 milliliters of concentrated hydrochloric acid was prepared and then diluted to 500 milliliters and adjusted to pH 7 with sodium hydroxide. The resulting precipitate of stannous hydroxide which formed was filtered under vacuum and washed several times with distilled water to remove sodium chloride.
  • This precipitate was dissolved in a solution of 75 grams of 2-mercaptoethanol and 150 milliliters of water, previously adjusted to pH 10 with sodium hydroxide.
  • This solution was then diluted to 267 milliliters with water and placed in a Hull cell. Five grams of sodium hydroxide were added to the bath.
  • This method can also be used to plate silver and gold on brass or copper by substituting 30 grams of Ag(NO or 20 grams of HAuCl -3H O for the SnCl' -2H O. The tallow treatment is omitted.
  • Example 2 An electroplating bath was prepared by dissolving 15 grams of cupr-ous oxide in a solution of 75 grams of mercaptoacetic acid in milliliters of water, previously adjusted to pH 10 with sodium hydroxide.
  • the resulting copper was bright and attractive over the whole current density range.
  • Mercaptoethylamine can be substituted for mercaptoacetic acid in this process, in equivalent amounts, with similar results.
  • Example 3 A solution of 20 grams of l-thioglycerol and 20 milliliters of water was adjusted to pH 10 with sodium hydroxide. Ten grams of cadmium oxide were then added to this solution in small quantities and the whole was made up to 267 milliliters with water.
  • Example 4 Eight grams of ZnO were dissolved in 200 milliliters of water, and sodium hydroxide was added until the pH of the solution was 9. The resulting precipitate was filtered and washed with water.
  • This precipitate was then dissolved in a solution of 200 milliliters of water and 25 grams of Z-mercaptoethanol. The pH of this solution was adjusted to 10 with sodium hydroxide and the solution was then made to 267 milliliters with water.
  • This solution was used as an electroplating bath, using a steel cathode, a zinc anode and a current of 0.5 ampere and volts.
  • the resulting zinc plate was bright in the intermediate current density range.
  • An improved electroplating bath consisting essentially of an aqueous solution of a metal salt of a compound of the formula where R is selected from the group consisting of hydrogen, COOH, alkyl radicals containing from 1 to 4 carbon atoms, and hydroxyalkyl radicals containing from 1 to 5 carbon atoms; and
  • X is selected from the group consisting of (CHR),,OH,
  • R' is selected from the group consisting of hydrogen, COOH, hydroxyalkyl radicals containing from 1 to 4 carbon atoms and alkyl radicals containing from 1 to 4 carbon atoms;
  • n is a whole positive number less than 3 the metal in said salt being selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
  • An electroplating bath consisting essentially of an aqueous solution of a Z-mercaptoethanol salt of a metal selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
  • a method for the electrodeposition of tin, copper, silver, gold, cadmium and zinc comprising passing an electric current from a suitable anode to a cathode to be plated, through a bath consisting essentially of an aqueous solution of a metal salt of a compound of the formula where R is selected from the group consisting of hydrogen,
  • X is selected from the group consisting of (CHR'),,OH,
  • R is selected from the group consisting of hydrogen, COOH, hydr-oxyalkyl radicals containing from 1 to 4 carbon atoms and alkyl radicals containing from 1 to 4 carbon atoms;
  • n is a whole positive number less than 3 the metal in said salt being selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
  • a method for the electrodeposition of tin, copper, silver, gold, cadmium and Zinc comprising passing an electric current from a suitable anode to a cathode to be plated, through an aqueous bath consisting essentially of a Z-mercaptoethanol salt of the metal to be thus deposited.

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  • 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)

Description

United States Patent 3,238,112 ELECTROPLATIN G OF METALS USING MER- CAPTO-METAL COMPLEX SALTS John H. Haslam, Landenberg, P2,, assignor to E. I. du
Pont de Nemours and Company, Wilmington, Del., a
corporation of Delaware No Drawing. Filed July 3, 1962, Ser. No. 207,401
4 Claims. (Cl. 20445) {This invention relates to compositions and processes for the electrodeposition of metals. It is more particularly directed to electroplating methods using baths containing mecapto compounds.
It has been found that plating baths containing mercapto compounds have a number of advantages not possessed by conventional plating baths. For example, the need for using such highly toxic substances as cyanide in the baths is eliminated. The baths give high efiiciency, both at the anode and at the cathode. They can be used at high pH levels, with their attendant advantages. These baths have excellent throwing power, give a high quality plate, and have good conductivity. They also permit the use of copper and tin in their lower valence states, thereby saving plating current.
The mercapto compounds which can be used according to this invention are those of the formula where R is hydrogen, COOH, an alkyl radical containing from 1 to 4 carbon atoms, or a hydroyalkyl radical containing from 1 to 5 carbon atoms;
where R is hydrogen, COOH, a hydroxyalkyl radical containing from 1 to 4 carbon atoms, or an alkyl radical containing from 1 to 4 carbon atoms; and
n is 1 or 2.
Preferred for use are Z-mercaptoethanol Z-mercaptopropanol l-mercaptopropanol-Z Z-mercaptobutanol 2-mercaptobutanol-3 l-thioglycerol 2 thioglycerol a-Thiosorbitol Mercaptoacetic acid Z-mercaptosuccinic acid Mercaptoethylamine The metals which can be electrically deposited according to this invention are copper, tin, silver, gold, cadmium and zinc. Alloys of these metals, such as brass, can also be deposited. These metals can be deposited on such other metals as steel, copper and brass.
The electroplating bath is prepared by dissolving a conventional amount of a salt of the metal to be deposited in an aqueous solution of a mercapto compound which has been previously brought to pH l011 with a stoichiometric amount of sodium or potassium hydroxide. The mercapto compound should ordinarily be present at a concentration of from 2 to moles per mole of the metal to be deposited. In the baths, the metals to be deposited are naturally present as salts with the mercapto compound. Excess sodium or potassium hydroxide in the bath generally improves plate quality and increases the conductivity of the bath. Conventional brightening 3,238,112 Patented Mar. 1, 1966 agents, such as Rochelle salts or sodium hydroxyacetate and other additives, can also be added if desired.
The plating is then carried out with conventional electr oplating equipment, using ordinary electroplating techmques.
In order that this invention be better understood, the following examples are submitted:
Example 1 A solution of 45 grams of SnC1 -2H O, milliliters of water and 10 milliliters of concentrated hydrochloric acid was prepared and then diluted to 500 milliliters and adjusted to pH 7 with sodium hydroxide. The resulting precipitate of stannous hydroxide which formed was filtered under vacuum and washed several times with distilled water to remove sodium chloride.
This precipitate was dissolved in a solution of 75 grams of 2-mercaptoethanol and 150 milliliters of water, previously adjusted to pH 10 with sodium hydroxide.
This solution was then diluted to 267 milliliters with water and placed in a Hull cell. Five grams of sodium hydroxide were added to the bath.
Steel plates were used as a cathode and a tin plate was used as an anode. These plates were immersed in the bath and a current of 1 /2 volts Was passed through.
The resulting tin plate was matte-white. Both cathode and anode efliciency were These steel plates were then brightened by dipping them into hot tallow, maintained at 207 C., for approximately 15 seconds.
i This method can also be used to plate silver and gold on brass or copper by substituting 30 grams of Ag(NO or 20 grams of HAuCl -3H O for the SnCl' -2H O. The tallow treatment is omitted.
Example 2 An electroplating bath was prepared by dissolving 15 grams of cupr-ous oxide in a solution of 75 grams of mercaptoacetic acid in milliliters of water, previously adjusted to pH 10 with sodium hydroxide.
This solution was then placed in a Hull cell, 10 grams of sodium hydroxide were added, and the resulting bath was used to electroplate copper on steel, using a copper anode and a current of 2 /2 volts and 1 ampere.
The resulting copper was bright and attractive over the whole current density range.
Mercaptoethylamine can be substituted for mercaptoacetic acid in this process, in equivalent amounts, with similar results.
Example 3 A solution of 20 grams of l-thioglycerol and 20 milliliters of water was adjusted to pH 10 with sodium hydroxide. Ten grams of cadmium oxide were then added to this solution in small quantities and the whole was made up to 267 milliliters with water.
This solution was then placed in a Hull cell, 5 grams of sodium hydroxide were added, and the bath was electrolyzed using a steel cathode, a cadmium anode and a current of 0.5 ampere and 1 volt. The resulting plate was bright and the anode and cathode plating efficiencies were essentially 100%.
Example 4 Eight grams of ZnO were dissolved in 200 milliliters of water, and sodium hydroxide was added until the pH of the solution was 9. The resulting precipitate was filtered and washed with water.
This precipitate was then dissolved in a solution of 200 milliliters of water and 25 grams of Z-mercaptoethanol. The pH of this solution was adjusted to 10 with sodium hydroxide and the solution was then made to 267 milliliters with water.
This solution was used as an electroplating bath, using a steel cathode, a zinc anode and a current of 0.5 ampere and volts.
The resulting zinc plate was bright in the intermediate current density range.
The embodiments of the invention in which an exclusive property or privilege is claimed are:
1. An improved electroplating bath consisting essentially of an aqueous solution of a metal salt of a compound of the formula where R is selected from the group consisting of hydrogen, COOH, alkyl radicals containing from 1 to 4 carbon atoms, and hydroxyalkyl radicals containing from 1 to 5 carbon atoms; and
X is selected from the group consisting of (CHR),,OH,
(CHR'),,'NH and (OHR),, COOH where R' is selected from the group consisting of hydrogen, COOH, hydroxyalkyl radicals containing from 1 to 4 carbon atoms and alkyl radicals containing from 1 to 4 carbon atoms; and
n is a whole positive number less than 3 the metal in said salt being selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
2. An electroplating bath consisting essentially of an aqueous solution of a Z-mercaptoethanol salt of a metal selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
3. A method for the electrodeposition of tin, copper, silver, gold, cadmium and zinc, said method comprising passing an electric current from a suitable anode to a cathode to be plated, through a bath consisting essentially of an aqueous solution of a metal salt of a compound of the formula where R is selected from the group consisting of hydrogen,
COOH, alkyl radicals containing from 1 to 4 carbon atoms, and hydroxyalkyl radicals containing from 1 to 5 carbon atoms; and
X is selected from the group consisting of (CHR'),,OH,
(CHRO NH and (CHR) COOH where R is selected from the group consisting of hydrogen, COOH, hydr-oxyalkyl radicals containing from 1 to 4 carbon atoms and alkyl radicals containing from 1 to 4 carbon atoms; and
n is a whole positive number less than 3 the metal in said salt being selected from the group consisting of tin, copper, silver, gold, cadmium and zinc.
4. A method for the electrodeposition of tin, copper, silver, gold, cadmium and Zinc, said method comprising passing an electric current from a suitable anode to a cathode to be plated, through an aqueous bath consisting essentially of a Z-mercaptoethanol salt of the metal to be thus deposited.
References Cited by the Examiner UNITED STATES PATENTS 1,857,507 5/1932 Hichman et al. 20446 2,113,517 4/1938 Powell et al. 20446 2,495,668 1/1950 Wilson et al 204-52.l
FOREIGN PATENTS 690,978 4/ 1953 Great Britain.
JOHN H. MACK, Primary Examiner.
JOHN R. SPECK, Examiner.

Claims (1)

1. AN IMPROVED ELECTROPLATING BATH CONSISTING ESSENTIALLY OF AN AQUEOUS SOLUTION OF A METAL SALT OF A COMPOUND OF THE FORMULA
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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3520785A (en) * 1969-04-14 1970-07-14 Robert Duva Electroplating gold and thiomalate electrolyte therefor
JPS5148731A (en) * 1974-10-24 1976-04-27 Nippon Dento Kogyo Kk Kin parajiumugokinmetsukiho
JPS5337149A (en) * 1976-09-20 1978-04-06 Toho Kasei Kougiyou Kk Gold plating method
US4126524A (en) * 1975-03-12 1978-11-21 Technic, Inc. Silver complex, method of making said complex and method and electrolyte containing said complex for electroplating silver and silver alloys
DE2829979A1 (en) * 1977-07-08 1979-01-18 Systemes Traitements Surfaces ELECTROLYSIS BATH FOR THE DEPOSITION OF GOLD-COPPER-CADMIUM ALLOYS AND ITS APPLICATION IN GALVANO TECHNOLOGY
US4246077A (en) * 1975-03-12 1981-01-20 Technic, Inc. Non-cyanide bright silver electroplating bath therefor, silver compounds and method of making silver compounds
US4247372A (en) * 1978-08-29 1981-01-27 Learonal, Inc. Silver plating
US4399006A (en) * 1978-08-29 1983-08-16 Learonal, Inc. Silver plating
US4502927A (en) * 1981-11-18 1985-03-05 International Business Machines Corporation Electrodeposition of chromium and its alloys
USH1136H (en) 1991-11-29 1993-02-02 The United States Of America As Represented By The Secretary Of The Air Force Electrolytic deposition and recovery of silver
WO2010142437A1 (en) * 2009-06-09 2010-12-16 Coventya S.P.A. Cyanide-free electrolyte for galvanic deposition of gold or alloys thereof
WO2012076174A3 (en) * 2010-12-07 2013-02-14 Coventya S.P.A. Electrolyte for the electrochemical deposition of gold alloys and process for the production thereof
CN105648486A (en) * 2014-11-28 2016-06-08 李婧 Preparation method of electroplating liquid of mercapto carboxylic acid metal complex and surface treatment method thereof
US20210009785A1 (en) * 2018-02-19 2021-01-14 Arkema Inc. Accelerator solutions useful for resin curing

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1857507A (en) * 1929-10-22 1932-05-10 Eastman Kodak Co Process for the separation of silver by electrolysis
US2113517A (en) * 1935-01-26 1938-04-05 Johnson Matthey Co Ltd Electrodeposition of silver
US2495668A (en) * 1946-12-21 1950-01-24 Harshaw Chem Corp Electrodeposition of copper
GB690978A (en) * 1950-09-15 1953-04-29 Hanson Van Winkle Munning Co Bright silver plating

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1857507A (en) * 1929-10-22 1932-05-10 Eastman Kodak Co Process for the separation of silver by electrolysis
US2113517A (en) * 1935-01-26 1938-04-05 Johnson Matthey Co Ltd Electrodeposition of silver
US2495668A (en) * 1946-12-21 1950-01-24 Harshaw Chem Corp Electrodeposition of copper
GB690978A (en) * 1950-09-15 1953-04-29 Hanson Van Winkle Munning Co Bright silver plating

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3520785A (en) * 1969-04-14 1970-07-14 Robert Duva Electroplating gold and thiomalate electrolyte therefor
JPS5148731A (en) * 1974-10-24 1976-04-27 Nippon Dento Kogyo Kk Kin parajiumugokinmetsukiho
US4126524A (en) * 1975-03-12 1978-11-21 Technic, Inc. Silver complex, method of making said complex and method and electrolyte containing said complex for electroplating silver and silver alloys
US4246077A (en) * 1975-03-12 1981-01-20 Technic, Inc. Non-cyanide bright silver electroplating bath therefor, silver compounds and method of making silver compounds
JPS5337149A (en) * 1976-09-20 1978-04-06 Toho Kasei Kougiyou Kk Gold plating method
DE2829979C3 (en) * 1977-07-08 1990-06-21 Systemes Traitements Surfaces AQUEOUS BATH FOR GALVANIC DEPOSITION OF GOLD COPPER CADMIUM ALLOYS
DE2829979A1 (en) * 1977-07-08 1979-01-18 Systemes Traitements Surfaces ELECTROLYSIS BATH FOR THE DEPOSITION OF GOLD-COPPER-CADMIUM ALLOYS AND ITS APPLICATION IN GALVANO TECHNOLOGY
US4247372A (en) * 1978-08-29 1981-01-27 Learonal, Inc. Silver plating
US4399006A (en) * 1978-08-29 1983-08-16 Learonal, Inc. Silver plating
US4502927A (en) * 1981-11-18 1985-03-05 International Business Machines Corporation Electrodeposition of chromium and its alloys
USH1136H (en) 1991-11-29 1993-02-02 The United States Of America As Represented By The Secretary Of The Air Force Electrolytic deposition and recovery of silver
WO2010142437A1 (en) * 2009-06-09 2010-12-16 Coventya S.P.A. Cyanide-free electrolyte for galvanic deposition of gold or alloys thereof
WO2012076174A3 (en) * 2010-12-07 2013-02-14 Coventya S.P.A. Electrolyte for the electrochemical deposition of gold alloys and process for the production thereof
CN105648486A (en) * 2014-11-28 2016-06-08 李婧 Preparation method of electroplating liquid of mercapto carboxylic acid metal complex and surface treatment method thereof
CN105646305A (en) * 2014-11-28 2016-06-08 李婧 Preparation method of mercapto carboxylic acid metal complex
US20210009785A1 (en) * 2018-02-19 2021-01-14 Arkema Inc. Accelerator solutions useful for resin curing

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