US3033703A - Electroless plating of copper - Google Patents

Electroless plating of copper Download PDF

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Publication number
US3033703A
US3033703A US778736A US77873658A US3033703A US 3033703 A US3033703 A US 3033703A US 778736 A US778736 A US 778736A US 77873658 A US77873658 A US 77873658A US 3033703 A US3033703 A US 3033703A
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United States
Prior art keywords
copper
bath
solution
mol
salt
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
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US778736A
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English (en)
Inventor
Jr Frederick W Schneble
Mccormack John
Rudolph J Zeblisky
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Kollmorgen Corp
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Photocircuits Corp
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Publication date
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Priority to US778736A priority Critical patent/US3033703A/en
Priority to GB25498/59A priority patent/GB924049A/en
Priority to CH8136959A priority patent/CH413539A/de
Priority to BE585448A priority patent/BE585448A/fr
Application granted granted Critical
Publication of US3033703A publication Critical patent/US3033703A/en
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    • 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
    • C23C18/38—Coating with copper
    • C23C18/40—Coating with copper using reducing agents
    • C23C18/405—Formaldehyde

Definitions

  • the present invention represents an advance over prior electroless plating baths and the processes in which they are used in that the process of plating may be stopped or started at will and the bath composition is such that it may be used continuously and is not limited to batch usage since it can be replenished.
  • This quality of the bath solutions also allows the composition thereof to be maintained uniform which results in the production of an even, uniformly grained plate.
  • the present invention further represents an advance over those processes and baths used heretofore in that the present process can be used to deposit metallic copper without resort to electricity on ordinarily unreceptive surfaces such as plastic surfaces, and on surfaces of metallic copper, iron, nickel, cobalt, aluminum, silver, gold and alloys thereof, such as stainless steel, brass, sterling silver, etc.
  • Surfaces on which copper is to be deposited are generally activated or sensitized by a pretreatment step.
  • the treatment depends upon the chemical nature of the material to be treated and upon its wettability. Readily wetted surfaces require no such pretreatment.
  • the pretreatment of plastic surfaces consists in wetting the surfaces, as by means of a detergent'such as Triton X-l00 a product of the Rohm & Haas Company, of Philadelphia, in a concentration of about 1 ml. of detergent per liter of water. Instead of wetting the surfaces they may be pretreated by roughening said surfaces slightly by the application thereto of abrasive material. The treated surface whether it has been wetted or roughened by abrasion is rinsed thoroughly with water.
  • the rinsed surface is then preferably initially sensitized by treating it with a solution containing grams of stannous chloride (SnCl .2H O) and 40 ml. of hydrochloric acid (37% HCl) per liter of water.
  • stannous chloride SnCl .2H O
  • hydrochloric acid 37% HCl
  • the ranges within which these two ingredients may be varied is from 5 to 150 grams of stannous chloride and which may be further acidified by the addition of up to ml. of hydrochloric acid.
  • the surface to be sensitized is usually contacted with this solution for about 10 minutes.
  • stannous chloride other stannous tin compounds such as stannous fluoborate and stannous sulphate would be suitable in this formulation.
  • sensitized surfaces are removed from contact with this solution and thoroughly rinsed with water to insure the complete removal of stannous ions from the surfaces. Occasionally it may be desirable to use a rinse Water containing from 0.5 to 25 ml. 'of hydrochloric acid (37% HCl) per liter of water. The removal of soluble stannous ions is necessary since their presence in the second sensitizer or seeder bath would result in its contamination and loss of effectiveness.
  • the surface to be plated is then preferably further I sensitized by using a second sensitizer or seeder bath which is contacted with the surface which is to receive the copper plating.
  • This bath solution consists of 010 gram per liter of palladium chloride PdCl 1 ml. per liter of hydrochloric acid (37% HQ) and 1 ml. per liter of Triton X-100.
  • the palladium chloride may be substituted for by auric chloride HAuCl in amounts ranging from 0.045 to upwards of 1.8 grams per liter.
  • This preferred composition of the second sensitizer solution or seeder bath may be varied such that the metal content will range from 0.025 gram per liter to 1 gram per liter.
  • the amount of acid may also be increased up to 25 ml. of acid per liter, although the best results are obtained using about 1 ml. of acid per liter.
  • the use of a wetting agent is essential in instances in which the base materials are not easily wetted but are not necessary where the base materials are easily wetted. Contact of the surface with this second sensitizer solution or seeder bath normally lasts for at least two minutes.
  • the second sensitizer or seeder bath is thoroughly rinsed from the surface which has been in contact with it.
  • the preferred electroless copper plating bath composition has been found to be the following:
  • the amount of sodium hydroxide present in this bath is such that it will provide a pH in excess of 11.0, preferably from 11.6 to 12.5, and optimally 11.75, when diluted with water to make one liter. 1
  • the foregoing compounds are preferably dissolved in 1 liter of water.
  • concentration of this solution may be varied, however, by using as little water as 250 mls. and as much as 2000 ads, and the pH will vary accordingly, but always above pH 11.0.
  • Salts other than copper sulphate may be used which contain either cupn'c or cuprous ions if they are used on the basis of equivalent mols of copper and in a concentration of from 0.02 to 0.25 mol of copper per liter of solution.
  • these salts which are suitable for use in place of copper sulphate are cupric and cuprous chloride, cupric carbonate, cupric acetate and cupric and cuprous oxides.
  • Potassium hydroxide may be used in place of sodium hydroxide on a chemically equivalent basis.
  • the tartrate salts are preferably used as complexing agents, because of their economy but sodium citrate or sodium gluconate may be substituted on an equivalent basis with from 0.002 to 0.25 mol of the complexing agent per liter.
  • the critical relation which must be observed is that the pH must be adjusted so that there is a proper balance between the strength of the alkalinity of the solution and the amount of such complexing agent as may be present.
  • the diagrammatic figure shows the relation of the molar concentrations of an alkali metal hydroxide, sodium hydroxide as the ordinate, plotted against the molar concentrations of the complexing agent, Rochelle salts 'as the abscissa, up to the maximum concentration of 0.25 mol of Rochelle salts per liter, a value which is not to be exceeded in view of the limit of 0.25 mol of copper per liter of solution.
  • the concentration of copper salt in the bath be kept below 0.25 mol and that there also be more copper ions in solution than Rochelle salts on an equivalent basis. Under these conditions the bath will have a clouded appearance.
  • the pH of the bath be at least 11.0 and that the equivalent concentration of the sodium or potassium hydroxide be at least five times that of the Rochelle salts. It is also important that the mol concentration of the sodium hydroxide or potassium hydroxide should not exceed seven times the mol concentration of the Rochelle sa1ts.
  • a fast working concentrated bath according to the present invention is a fast working concentrated bath according to the present invention.
  • Formaldehyde 120.0 Water to make 1000 ml. solution.
  • a more dilute bath, which is economical to establish has the composition:
  • the replenishment of certain compounds in the baths composition over periods of use usually comprise the addition of a suitable copper salt, the addition of a complexing agent, the renewal of the reducing agent and addition of alkali to maintain the desired pH in excess of pH 11.0.
  • a bath for the electroless plating of copper which consists essentially of from 0.02 to 0.25 mol of a water soluble copper salt, from 0.25 to 2.1 mols of formaldehyde, from 0.002 to 0.25 mol and in an amount less than that necessary to completely complex said copper salt of a copper complexing salt selected from the group consisting of Rochelle salts, sodium gluconate, and sodium citrate, alkali metal hydroxide from 5 to 7 times the number of mols of the copper complexing salt and sufficient to give the bath a pH of at least 11.0 and water sufficient to give one liter of bath solution.
  • a copper complexing salt selected from the group consisting of Rochelle salts, sodium gluconate, and sodium citrate, alkali metal hydroxide from 5 to 7 times the number of mols of the copper complexing salt and sufficient to give the bath a pH of at least 11.0 and water sufficient to give one liter of bath solution.
  • a bath as set forth in claim 1 wherein the complexing agent is Rochelle salts.
  • a bath for the electroless deposition of copper which consists of:
  • a process for the electroless plating of copper which comprises immersing a surface to be plated in an aqueous bath consisting essentially of a water soluble copper salt in an amount from 0.02 to 0.25 mol, from 0.25 to 2.1 mols of formaldehyde, a copper complexing salt selected from the group consisting of Rochelle salts, sodium gluconate and sodium citrate from 0.002 to 0.25 mol and less than that necessary to completely complex said copper salt, an alkali metal hydroxide sufiicient to give the bath a pH of at least 11.0 and in a molar quantity of from 5 to 7 times the number of mols of the copper complexing salt in each liter of solution, maintaining the surface in said bath until a deposit of the tion containing stannous ions, washing said surface, seeding the sensitized surface with a solution containing ions selected from the group consisting of palladium and gold, washing said surface preliminary to contacting the surface thus prepared with an electroless copper plating bath as claimedv in claim

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemically Coating (AREA)
US778736A 1958-12-08 1958-12-08 Electroless plating of copper Expired - Lifetime US3033703A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US778736A US3033703A (en) 1958-12-08 1958-12-08 Electroless plating of copper
GB25498/59A GB924049A (en) 1958-12-08 1959-07-24 Electroless plating of copper
CH8136959A CH413539A (de) 1958-12-08 1959-12-02 Verfahren zum stromlosen Verkupfern
BE585448A BE585448A (fr) 1958-12-08 1959-12-08 Procédé de cuivrage non électrolytique et solution utilisées.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US778736A US3033703A (en) 1958-12-08 1958-12-08 Electroless plating of copper

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US3033703A true US3033703A (en) 1962-05-08

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US (1) US3033703A (fr)
BE (1) BE585448A (fr)
CH (1) CH413539A (fr)
GB (1) GB924049A (fr)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3164908A (en) * 1961-09-18 1965-01-12 United Aircraft Corp Measurement methods and gauges
US3222195A (en) * 1962-02-23 1965-12-07 Pearlstein Fred Stabilized electroless copper solution
US3313642A (en) * 1964-01-17 1967-04-11 Thomas Bonar & Co Canada Ltd Process of modifying the surface properties of polyolefin film
US3340161A (en) * 1964-02-19 1967-09-05 Sperry Rand Corp Printed circuits and method of manufacture thereof
US3340164A (en) * 1963-12-26 1967-09-05 Sperry Rand Corp Method of copper plating anodized aluminum
US3341350A (en) * 1964-09-30 1967-09-12 Philip D Anderson Method of preparing a uranium article for a protective coating
US3370974A (en) * 1965-10-20 1968-02-27 Ivan C. Hepfer Electroless plating on non-conductive materials
US3421922A (en) * 1965-03-08 1969-01-14 Bruce W Wilson Process for preconditioning a nonmetallic surface for chemically depositing a metal thereon
US3449176A (en) * 1966-01-14 1969-06-10 Minnesota Mining & Mfg Coating of solid substrates
US3725108A (en) * 1969-03-05 1973-04-03 Enthone Chemical reduction metal plated diallylphthalate polymer and preparation process
US3791848A (en) * 1972-05-19 1974-02-12 Western Electric Co A method of improving the adherence of a metal deposit to a polyimide surface
US3853589A (en) * 1970-11-09 1974-12-10 Ici Ltd Metal deposition process
US3867167A (en) * 1970-10-07 1975-02-18 Fuji Photo Film Co Ltd Method for production of photographic material
USRE29039E (en) * 1969-11-26 1976-11-16 Imperial Chemical Industries Limited Metal deposition process
US4002779A (en) * 1974-05-24 1977-01-11 Hoechst Aktiengesellschaft Process for the manufacture of electroconductive non-woven fabrics
US4039714A (en) * 1971-05-28 1977-08-02 Dr. -Ing. Max Schloetter Pretreatment of plastic materials for metal plating
US4066804A (en) * 1969-11-26 1978-01-03 Imperial Chemical Industries Limited Metal deposition process
US4272570A (en) * 1980-04-11 1981-06-09 Sunbeam Corporation Provision of surface layers of copper or copper alloyed with zinc on die castings of zinc or zinc alloys
USRE31694E (en) * 1976-02-19 1984-10-02 Macdermid Incorporated Apparatus and method for automatically maintaining an electroless copper plating bath
US4710224A (en) * 1983-03-05 1987-12-01 Degussa Aktiengesellschaft Process for introducing bath components into electrolytic and currentless baths
US4839023A (en) * 1987-09-16 1989-06-13 Exxon Research And Engineering Company Once-through coking with hydrotreating and fluid catalytic cracking
US4981725A (en) * 1972-07-11 1991-01-01 Amp-Akzo Corporation Process and composition for sensitizing articles for metallization
US5419926A (en) * 1993-11-22 1995-05-30 Lilly London, Inc. Ammonia-free deposition of copper by disproportionation
US20080148904A1 (en) * 2004-08-20 2008-06-26 Masanori Tomonari Copper Microparticle and Process for Producing the Same

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BR112013008950A2 (pt) * 2010-10-13 2019-09-24 Univ Of Windsor processo para galvanização eletroquímica de um metal galvânico sobre um substrato, processo para galvanização eletroquímica de metal galvânico de níquel ou de liga de nível sobre um substrato metálico de magnésio, processo para galvanização eletroquímica de sobre sobre um substrato, processo para galvanização eletroquímica de cibre galvânico sobre um substrato, e processo para galvanização eletroquímica de metal galvânico de níquel-boro sobre um substrato de magnésio
US8900998B2 (en) 2012-11-21 2014-12-02 University Of Windsor Process for electroless deposition of gold and gold alloys on silicon

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454610A (en) * 1946-08-13 1948-11-23 Narcus Harold Method for metalization on nonconductors
US2702253A (en) * 1950-11-01 1955-02-15 Gasaccumulator Svenska Ab Surface metallizing method
US2872359A (en) * 1956-12-03 1959-02-03 Sylvania Electric Prod Copper sensitizers
US2874072A (en) * 1956-09-17 1959-02-17 Gen Electric Autocatalytic copper plating process and solution
US2930106A (en) * 1957-03-14 1960-03-29 American Felt Co Gaskets

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454610A (en) * 1946-08-13 1948-11-23 Narcus Harold Method for metalization on nonconductors
US2702253A (en) * 1950-11-01 1955-02-15 Gasaccumulator Svenska Ab Surface metallizing method
US2874072A (en) * 1956-09-17 1959-02-17 Gen Electric Autocatalytic copper plating process and solution
US2872359A (en) * 1956-12-03 1959-02-03 Sylvania Electric Prod Copper sensitizers
US2930106A (en) * 1957-03-14 1960-03-29 American Felt Co Gaskets

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3164908A (en) * 1961-09-18 1965-01-12 United Aircraft Corp Measurement methods and gauges
US3222195A (en) * 1962-02-23 1965-12-07 Pearlstein Fred Stabilized electroless copper solution
US3340164A (en) * 1963-12-26 1967-09-05 Sperry Rand Corp Method of copper plating anodized aluminum
US3313642A (en) * 1964-01-17 1967-04-11 Thomas Bonar & Co Canada Ltd Process of modifying the surface properties of polyolefin film
US3340161A (en) * 1964-02-19 1967-09-05 Sperry Rand Corp Printed circuits and method of manufacture thereof
US3341350A (en) * 1964-09-30 1967-09-12 Philip D Anderson Method of preparing a uranium article for a protective coating
US3421922A (en) * 1965-03-08 1969-01-14 Bruce W Wilson Process for preconditioning a nonmetallic surface for chemically depositing a metal thereon
US3370974A (en) * 1965-10-20 1968-02-27 Ivan C. Hepfer Electroless plating on non-conductive materials
US3449176A (en) * 1966-01-14 1969-06-10 Minnesota Mining & Mfg Coating of solid substrates
US3725108A (en) * 1969-03-05 1973-04-03 Enthone Chemical reduction metal plated diallylphthalate polymer and preparation process
US4066804A (en) * 1969-11-26 1978-01-03 Imperial Chemical Industries Limited Metal deposition process
USRE29039E (en) * 1969-11-26 1976-11-16 Imperial Chemical Industries Limited Metal deposition process
US3867167A (en) * 1970-10-07 1975-02-18 Fuji Photo Film Co Ltd Method for production of photographic material
US3853589A (en) * 1970-11-09 1974-12-10 Ici Ltd Metal deposition process
US4039714A (en) * 1971-05-28 1977-08-02 Dr. -Ing. Max Schloetter Pretreatment of plastic materials for metal plating
US3791848A (en) * 1972-05-19 1974-02-12 Western Electric Co A method of improving the adherence of a metal deposit to a polyimide surface
US4981725A (en) * 1972-07-11 1991-01-01 Amp-Akzo Corporation Process and composition for sensitizing articles for metallization
US4002779A (en) * 1974-05-24 1977-01-11 Hoechst Aktiengesellschaft Process for the manufacture of electroconductive non-woven fabrics
USRE31694E (en) * 1976-02-19 1984-10-02 Macdermid Incorporated Apparatus and method for automatically maintaining an electroless copper plating bath
US4272570A (en) * 1980-04-11 1981-06-09 Sunbeam Corporation Provision of surface layers of copper or copper alloyed with zinc on die castings of zinc or zinc alloys
US4710224A (en) * 1983-03-05 1987-12-01 Degussa Aktiengesellschaft Process for introducing bath components into electrolytic and currentless baths
US4839023A (en) * 1987-09-16 1989-06-13 Exxon Research And Engineering Company Once-through coking with hydrotreating and fluid catalytic cracking
US5419926A (en) * 1993-11-22 1995-05-30 Lilly London, Inc. Ammonia-free deposition of copper by disproportionation
US20080148904A1 (en) * 2004-08-20 2008-06-26 Masanori Tomonari Copper Microparticle and Process for Producing the Same
US7828872B2 (en) * 2004-08-20 2010-11-09 Ishihara Sangyo Kaisha, Ltd. Copper microparticle and process for producing the same

Also Published As

Publication number Publication date
GB924049A (en) 1963-04-18
CH413539A (de) 1966-05-15
BE585448A (fr) 1960-06-08

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