US2495668A - Electrodeposition of copper - Google Patents

Electrodeposition of copper Download PDF

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Publication number
US2495668A
US2495668A US717800A US71780046A US2495668A US 2495668 A US2495668 A US 2495668A US 717800 A US717800 A US 717800A US 71780046 A US71780046 A US 71780046A US 2495668 A US2495668 A US 2495668A
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per liter
grams per
copper
case
cyanide
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US717800A
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Karl S Willson
David G Ellis
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Harshaw Chemical Co
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Harshaw Chemical Co
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    • 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
    • C25D3/38—Electroplating: Baths therefor from solutions of copper
    • C25D3/40—Electroplating: Baths therefor from solutions of copper from cyanide baths, e.g. with Cu+

Definitions

  • This invention relates to electrodeposition of copper and more particularly to improved processes and solutions for electrodeposition of bright copper.
  • HOCI-IzCHzSI-I Di thio diglycol (HOCI-IzCI-IzSSCHzCHzOH) B,B dihydroxyethyl sulfide (HOCH26H2SCH2CH2OH) Thioglycollic acid (HOCOCI-IzSI-I) That is, when such a deposit is made, it can be built up to substantial thickness, three ten-thousandths of an inch and more, and still exhibit greatly improved lustre as compared with the usual cyanide copper bath. Agitation of the solution results in improvement in lustre and makes possible the use of much higher current density, e. g. increase from a. s. f. to 60 a.
  • the compound to be suitable should have adequate solubility in the copper cyanide bath to make possible the maintenance in solution of a sufiici'ent quantity of the addition agent to achieve the desired result.
  • concentration of addition agent required for best results varies among the above indicated addition agents. In the case of B-mercapto ethanol the concentration should not be less than 0.05 gram per liter nor more than 10 grams per liter, a preferred range being from about 1 to 4 grams per liter. In the case of dithio diglycol, the concentration should not be less than 0.04 gram per liter nor more than 1.8 grams per liter, the optimum being from about 0.6 to 1.0 gram per liter.
  • the concentrations may be rather low, not less than about 0.007 gram per liter but may also be as high as 35 grams per liter, a, preferred range being from 0.25 to grams per liter.
  • the concentration may run from 1 gram per liter to as high as 240 grams per liter, a preferred range being from 4 to 70 grams per liter.
  • An aqueous alkaline plating bath may be employed containing 4 to ounces to 150 grams per liter) of CuCN per gallon and the requisite amount of NaCN.
  • the preferred pH range is 9.5 to 11.5 but good results may be had from 8.5 to 12.5.
  • Free cyanide content may be from 0 to 11.5 grams per liter or more, the preferred range being 2 to 12 grams per liter. In general, increase of free cyanide is desirable with increasing CuCN content.
  • the temperature is preferably maintained between 130 F. and 150 F. although good results can be had between 120 F. and 160 F.
  • Preferred solutions and plating conditions would be, for example:
  • Example I CuCN grams per liter 30 Free cyanide do 12 B-mercapto ethanol do 4 Water Remainder pH 8.5 CD (continuous current) a. s. f 30 Temperature F 140
  • Example II CuCN "grams per liter" Free cyanide do 5 Dithiodiglycol do 0.6 Water Remainder pI-I 12.5 CD (continuous current) a. s. f 20 Temperature F
  • Example III CuCN grams per liter 120 Free cyanide do 12 BB dlhydroxyethyl sulfide do 70 Water Remainder pH 12.5 C. D. (interrupted current, 30 sec. on; 10 sec.
  • Example IV CuCN grams per Men. 30 Free cyanide do 2 Thioglycollic acid do 20 Water Remainder pH 10.0 CD (continuous current) a. s. f 20 Temperature ..F 140 Having thus described our invention, what we claim is:
  • An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and an amount of a brightening addition agent of the class consisting of B-mercapto ethanol, dithiodiglycol, B,B dihydroxyethyl sulfide and thioglycollic acid sufiicient to permit a brilliant cathodic deposit of copper upon the passage of an electric current from a copper anode to a cathode through the bath, the concentration of said brightening addition agent being from 0.05 gram per liter to grams per liter in the case of B-mercapto ethanol, from 0.04 gram per liter to 1.8 grams per liter in the case of dithiodiglycol, from 0.007 gram per liter to 35 grams per
  • a method which comprises electrodepositing copper from an aqueous, alkaline copper cyanide solution containing from 30 to 150 grams per liter of copper cyanide and from 2 to 12 grams per liter of free cyanide, there being added to such solution as a brightening agent a substance of the class consisting of B-mercapto ethanol, dithiodiglycol, B,B' dihydroxyethyl sulfide and thioglycollic acid, the concentration of said brightening addition agent being from 0.05 gram per liter to 10 grams per liter in the case of B-mercapto ethanol, from 0.04 gram per liter to 1.8 grams per liter in the case of dithiodiglycol, from 0.007 gram per liter to 35 grams per liter in the case of thioglycollic acid, and from 1 gram per liter to 240 grams per liter in the case of B,B' dihydroxyethyl sulfide.
  • a brightening agent a substance of the class
  • An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to grams per liter, 2. sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and containing as an organic brightening addition agent B-mercapto ethanol in concentration from 0.05 to 10 grams per liter.
  • An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and containing as an organic brightening addition agent 3,13 dihydroxyethyl sulfide in concentration from 1 to 240 grams per liter.
  • An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solu tion and containing as an organic brightening addition agent dithiodiglycol in concentration from 0.04 to 1.8 grams per liter.

Description

latented Jan. 24, 1950 SATES PATENT OFFICE Ohio, assignors to The Harshaw Chemical Company, Elyria, Ohio, a corporation of Ohio No Drawing. Application December 21, 1946, Serial No. 717,800
Claims. I
This invention relates to electrodeposition of copper and more particularly to improved processes and solutions for electrodeposition of bright copper.
We have now discovered that excellent bright copper deposits can be made by the inclusion in the copper cyanide plating solution of a suitable quantity of an organic compound of the class consisting of:
B-mercapto ethanol (HOCI-IzCHzSI-I) Di thio diglycol (HOCI-IzCI-IzSSCHzCHzOH) B,B dihydroxyethyl sulfide (HOCH26H2SCH2CH2OH) Thioglycollic acid (HOCOCI-IzSI-I) That is, when such a deposit is made, it can be built up to substantial thickness, three ten-thousandths of an inch and more, and still exhibit greatly improved lustre as compared with the usual cyanide copper bath. Agitation of the solution results in improvement in lustre and makes possible the use of much higher current density, e. g. increase from a. s. f. to 60 a. s. f. Interruption of the current at intervals, e. g. 1 minute on, 10 seconds off, reversal of the current every few seconds or use of alternating current superimposed on the direct current, all tend to produce improved lustre and more uniform deposits.
The compound to be suitable should have adequate solubility in the copper cyanide bath to make possible the maintenance in solution of a sufiici'ent quantity of the addition agent to achieve the desired result. The concentration of addition agent required for best results varies among the above indicated addition agents. In the case of B-mercapto ethanol the concentration should not be less than 0.05 gram per liter nor more than 10 grams per liter, a preferred range being from about 1 to 4 grams per liter. In the case of dithio diglycol, the concentration should not be less than 0.04 gram per liter nor more than 1.8 grams per liter, the optimum being from about 0.6 to 1.0 gram per liter. In the case of thicglycollic acid, the concentrations may be rather low, not less than about 0.007 gram per liter but may also be as high as 35 grams per liter, a, preferred range being from 0.25 to grams per liter. In the case of 3,18 dihydroxyethyl sulfide the concentration may run from 1 gram per liter to as high as 240 grams per liter, a preferred range being from 4 to 70 grams per liter.
An aqueous alkaline plating bath may be employed containing 4 to ounces to 150 grams per liter) of CuCN per gallon and the requisite amount of NaCN. The preferred pH range is 9.5 to 11.5 but good results may be had from 8.5 to 12.5. Free cyanide content may be from 0 to 11.5 grams per liter or more, the preferred range being 2 to 12 grams per liter. In general, increase of free cyanide is desirable with increasing CuCN content. The temperature is preferably maintained between 130 F. and 150 F. although good results can be had between 120 F. and 160 F.
Current is passed through the above indicated solutions from a copper anode to acathode at a cathode current density of from a very low value up to amperes per square foot.
Preferred solutions and plating conditions would be, for example:
Example I CuCN grams per liter 30 Free cyanide do 12 B-mercapto ethanol do 4 Water Remainder pH 8.5 CD (continuous current) a. s. f 30 Temperature F 140 Example II CuCN "grams per liter" Free cyanide do 5 Dithiodiglycol do 0.6 Water Remainder pI-I 12.5 CD (continuous current) a. s. f 20 Temperature F Example III CuCN grams per liter 120 Free cyanide do 12 BB dlhydroxyethyl sulfide do 70 Water Remainder pH 12.5 C. D. (interrupted current, 30 sec. on; 10 sec.
Off a. s. f 15 This bath gave brighter deposits with interrupted current than with continuous current.
Example IV CuCN grams per Men. 30 Free cyanide do 2 Thioglycollic acid do 20 Water Remainder pH 10.0 CD (continuous current) a. s. f 20 Temperature ..F 140 Having thus described our invention, what we claim is:
1. An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and an amount of a brightening addition agent of the class consisting of B-mercapto ethanol, dithiodiglycol, B,B dihydroxyethyl sulfide and thioglycollic acid sufiicient to permit a brilliant cathodic deposit of copper upon the passage of an electric current from a copper anode to a cathode through the bath, the concentration of said brightening addition agent being from 0.05 gram per liter to grams per liter in the case of B-mercapto ethanol, from 0.04 gram per liter to 1.8 grams per liter in the case of dithiodiglycol, from 0.007 gram per liter to 35 grams per liter in the case of thioglycollic acid, and from 1 gram per liter to 240 grams per liter in the case of B,B dihydroxyethyl sulfide.
2. A method which comprises electrodepositing copper from an aqueous, alkaline copper cyanide solution containing from 30 to 150 grams per liter of copper cyanide and from 2 to 12 grams per liter of free cyanide, there being added to such solution as a brightening agent a substance of the class consisting of B-mercapto ethanol, dithiodiglycol, B,B' dihydroxyethyl sulfide and thioglycollic acid, the concentration of said brightening addition agent being from 0.05 gram per liter to 10 grams per liter in the case of B-mercapto ethanol, from 0.04 gram per liter to 1.8 grams per liter in the case of dithiodiglycol, from 0.007 gram per liter to 35 grams per liter in the case of thioglycollic acid, and from 1 gram per liter to 240 grams per liter in the case of B,B' dihydroxyethyl sulfide.
3. An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to grams per liter, 2. sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and containing as an organic brightening addition agent B-mercapto ethanol in concentration from 0.05 to 10 grams per liter.
4. An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solution and containing as an organic brightening addition agent 3,13 dihydroxyethyl sulfide in concentration from 1 to 240 grams per liter.
5. An aqueous, alkaline electroplating bath which comprises an aqueous medium to which has been added a metal ion yielding material essentially consisting of copper cyanide in concentration from 30 to 150 grams per liter, a sufficient amount of sodium cyanide to produce from 2 to 12 grams per liter of free cyanide in the solu tion and containing as an organic brightening addition agent dithiodiglycol in concentration from 0.04 to 1.8 grams per liter.
KARL S. VIILLSON. DAVID G. ELLIS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,147,415 Tucker Feb. 14, 1939 2,195,409 Flett July 29, 1940 2,402,640 Lazier et al June 25, 1945 2,410,844 Signaigo et al Nov. 12, 1946 2,424,887 Henricks Apr. 2, 1947 OTHER REFERENCES The Metal Industry, March 1943, pages 134- 137, and Apr. 1, 1943, page 206.

Claims (1)

1. AN AQUEOUS, ALKALINE ELECTROPLATING BATH WHICH COMPRISES AN AQUEOUS MEDIUM TO WHICH HAS BEEN ADDED A METAL ION YIELDING MATERIAL ESSENTIALLY CONSISTING OF COPPER CYANIDE IN CONCENTRATION FROM 30 TO 150 GRAMS PER LITER, A SUFFICIENT AMOUNT OF SODIUM CYANIDE TO PRODUCE FROM 2 TO 12 GRAMS PER LITER OF FREE CYANIDE IN THE SOLUTION AND AN AMOUNT OF A BRIGHTENING ADDITION AGENT OF THE CLASS CONSISTING OF B-MERCAPTO ETHANOL, DITHIODIGLYCOL, B,B'' DIHYDROXYETHYL SULFIDE AND THIOGLYCOLLIC ACID SUFFICIENT TO PERMIT A BRILLIANT CATHODIC DEPOSIT OF COPPER UPON THE PASSAGE OF AN ELECTRIC CURRENT FROM A COPPER ANODE TO A CATHODE THROUGH THE BATH, THE CONCENTRATION OF SAID BRIGHTENING ADDITION AGENT BEING FROM 0.05 GRAM PER LITER TO 10 GRAMS PER LITER IN THE CASE OF B-MERCAPTO ETHANOL, FROM 0.04 GRAM PER LITER TO 1.8 GRAMS PER LITER IN THE CASE OF DITHIODIGLYCOL, FROM 0.007 GRAM PER LITER TO 35 GRAMS PER LITER IN THE CASE OF THIOGLYCOLLIC ACID, AND FROM 1 GRAM PER LITER TO 240 GRAMS PER LITER IN THE CASE OF B,B'' DIHYDROXYETHYL SULFIDE.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2612469A (en) * 1948-09-28 1952-09-30 Wire Coating And Mfg Company Rapid fine-grained copper electrodeposition
US2677654A (en) * 1951-05-10 1954-05-04 Poor & Co Copper electroplating and compositions therefor
DE1017001B (en) * 1953-10-14 1957-10-03 Metal & Thermit Corp Galvanic copper bath containing pyrophosphate
DE1017000B (en) * 1953-11-12 1957-10-03 Du Pont Bath and process for the electrodeposition of copper coatings
DE1055314B (en) * 1956-01-19 1959-04-16 Harshaw Chem Corp Cyanide bath and process for the galvanic deposition of shiny copper coatings
DE1087424B (en) * 1958-04-15 1960-08-18 Schering Ag Cyanide copper bath for galvanic deposition of uniformly glossy coatings
US3238112A (en) * 1962-07-03 1966-03-01 Du Pont Electroplating of metals using mercapto-metal complex salts

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147415A (en) * 1937-05-11 1939-02-14 Eastman Kodak Co Electroplating
US2195409A (en) * 1936-07-31 1940-04-02 Nat Aniline & Chem Co Inc Electrodeposition
US2402640A (en) * 1940-09-19 1946-06-25 Du Pont Chemical processes and product
US2410844A (en) * 1942-01-14 1946-11-12 Du Pont Metal plating process
US2424887A (en) * 1941-10-11 1947-07-29 Houdaille Hershey Corp Method and electrolyte for the electrodeposition of metals

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2195409A (en) * 1936-07-31 1940-04-02 Nat Aniline & Chem Co Inc Electrodeposition
US2147415A (en) * 1937-05-11 1939-02-14 Eastman Kodak Co Electroplating
US2402640A (en) * 1940-09-19 1946-06-25 Du Pont Chemical processes and product
US2424887A (en) * 1941-10-11 1947-07-29 Houdaille Hershey Corp Method and electrolyte for the electrodeposition of metals
US2410844A (en) * 1942-01-14 1946-11-12 Du Pont Metal plating process

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2612469A (en) * 1948-09-28 1952-09-30 Wire Coating And Mfg Company Rapid fine-grained copper electrodeposition
US2677654A (en) * 1951-05-10 1954-05-04 Poor & Co Copper electroplating and compositions therefor
DE1017001B (en) * 1953-10-14 1957-10-03 Metal & Thermit Corp Galvanic copper bath containing pyrophosphate
DE1017000B (en) * 1953-11-12 1957-10-03 Du Pont Bath and process for the electrodeposition of copper coatings
DE1055314B (en) * 1956-01-19 1959-04-16 Harshaw Chem Corp Cyanide bath and process for the galvanic deposition of shiny copper coatings
DE1087424B (en) * 1958-04-15 1960-08-18 Schering Ag Cyanide copper bath for galvanic deposition of uniformly glossy coatings
US3238112A (en) * 1962-07-03 1966-03-01 Du Pont Electroplating of metals using mercapto-metal complex salts

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