US3649343A - Chloride concentration control in immersion copper coating - Google Patents

Chloride concentration control in immersion copper coating Download PDF

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Publication number
US3649343A
US3649343A US79101A US3649343DA US3649343A US 3649343 A US3649343 A US 3649343A US 79101 A US79101 A US 79101A US 3649343D A US3649343D A US 3649343DA US 3649343 A US3649343 A US 3649343A
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Prior art keywords
coating
bath
copper
chloride
concentration
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US79101A
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English (en)
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Stuart Reed
Louis Schiffman
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Henkel Corp
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Amchem Products Inc
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Assigned to AMCHEM PRODUCTS, INC. A CORP. OF DEL. reassignment AMCHEM PRODUCTS, INC. A CORP. OF DEL. MERGER (SEE DOCUMENT FOR DETAILS). Assignors: AMCHEM PRODUCTS, INC. (MERGED INTO), HHC, INC. (CHANGED TO)
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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

Definitions

  • FIG. 4 9S i E 9 $25 5 5 WEIGHT OF STEEL COATED IN POUNDS (THOUSAND)
  • This invention relates to the deposition of copper from an aqueous acidic solution ofa copper salt, onto the surface ofa metal with a higher electrode potential than that of copper. More particularly, the invention concerns increasing the life of the coating bath by maintaining chloride ion concentration within predetermined bounds. This requires that the concentrate for makeup of the original bath as well as the composition employed to replenish the bath contain certain initial and predetermined concentrations of chloride so that chloride ion concentration may be established and controlled in the bath within predetermined critical limits.
  • the metals are rolled, drawn or otherwise subjected to pressures to change their size and shape.
  • a lubricating film or coating is first deposited on the surface ofthe metal so that the effect of frictional forces which develop may be avoided.
  • a relatively ductile and soft metal such as copper can provide suitable lubrication when deposited on the metal by plating the copper out onto the metal surface by immersion deposition from a suitable aqueous acidic solution ofa copper salt.
  • the copper content of the bath diminishes through its inclusion in the coating deposited on the surface.
  • the specific losses of the coating producing ingredients must be replaced so that the coating bath is maintained within its prescribed operating limits.
  • An operating bath is usually replenished with the original makeup formulation and the amount used for replenishing depends on how much copper has been depleted. Since there are other ingredients in the makeup formulation, they too are carried into the bath when replenishment occurs.
  • the bath is eventually dumped when coating color or quality deteriorates or coating weight drops off to an unacceptable level. When an operating bath is dumped it usually still contains quantities of essential ingredients sufficient to produce adherent coatings which have some lubricating ability.
  • U.S. Pat. No. 2,217,921 teaches that the coating bath is insensitive to wide variations in halide ion content, except that too low-halide concentration in the bath results in nonadherent coatings and too high a concentration slows down the coating process considerably.
  • a bath may be replenished many more times than is normally practiced, without loss of coating quality.
  • a coating bath can be operated for a longer period of time at the same rate of throughput.
  • the principal object ofthis invention is to provide a coating process which will prevent early and wasteful dumping of copper-coating baths.
  • An added object of this invention is to increase the work load in terms of total surface area coated by the same copper coating bath.
  • Yet another object of this invention is to provide a coating process which produces good quality copper coatings using less copper in the makeup material and to produce good visible quality coatings with lower coating weights.
  • This invention increases coating bath life of an aqueous acidic coating solution of a copper salt by maintaining chloride ion concentration within certain predetermined critical limits.
  • the chloride concentration when controlled in accordance with the teachings of this invention, allows for the production of coatings essentially uniform in weight throughout the life of the bath.
  • the bath life is extended considerably which ameliorates the considerable waste disposal problem inherent in the present day operation of copper coating baths.
  • the ferrous ion concentration in the bath is measured at certain intervals. This measurement is made in order to determine when to replenish the bath with a dry admixture ofthe original makeup formulation. Iron content is readily determined by a titration ofa bath sample with 0.1 N potassium permanganate. A 1 ml. titration corresponds to 5.6 grams/liter concentration of ferrous ion.
  • chloride can be added at each replenishment step at a predetermined rate as a function of iron buildup in the bath.
  • chloride ion can be added at an overall rate of from about 0.5 gram-ion/liter to about 6 gram-ions/liter for each 5.6 gram-ions/liter increase in ferrous ion concentration.
  • chloride ion should be added at an overall rate of from about 0.8 to about 2.0 gram-ions/liter for every 1 ml. increase in iron titration or 5.6 gram-ions/liter increase in ferrous ion concentration. This addition may be continued until total chloride concentration reaches from about 35 gramions/liter to about 40 gram-ions/liter at which time the bath is no longer useful.
  • the chloride salt in the makeup material should be that amount which, when added to water or the aqueous acidulated solution, will produce a chloride concentration in the coating solution of not more than 6 gram-ions/liter.
  • the initial chloride concentration should be from about 2.5 to 4.5 gram-ions/liter for acceptable coating weights to be initially produced and to facilitate a prolonged coating bath life.
  • a makeup material containing a source of copper, an inhibitor, and a water-soluble chloride salt is to be used for the bath startup and can be used as well for replenishing the bath as necessary.
  • a replenishing material consisting essentially of the same constituents, but present in different proportions, can be employed to replenish the working bath.
  • the depleted copper in the coating solution must be replaced to maintain the bath within its optimum operating limits.
  • the bath is maintained by suitable addition of makeup concentrate or replenishing concentrate.
  • chloride and copper should be added in definite proportions. As we have indicated, for each I ml. increase in iron titration or 5.6 gram-ions/liter increase in ferrous ion concentration, from about 4 g./l to about g./l of copper should be added. For each part by weight of copper added. from about 0.1 to about 0.6 parts by weight of chloride should be added to the operating bath. In the makeup material and replenishment material the amounts of copper and chloride present should be within these definite weight proportions. i.e., for each part by weight of copper present. from about 0.1 to about 0.6 parts by weight ofchloride should be present.
  • the source for copper can be any conveniently available copper salt employed in the art.
  • Preferred sources for the ad dition of copper to the coating bath are copper sulfate monohydrate, copper sulfate pentahydrate. tetraamine copper sulfate, or copper ammonium sulfate heptahydrate.
  • the amount of copper used in the bath may vary over a fairly wide range depending, of course, on quality and coating weight desired.
  • one of the advantages of the present invention is that it is possible to get high-quality coatings, previously requiring high-copper concentrations in the bath, by using much lower quantities of copper.
  • an original makeup bath containing as little as 10 lbs. of copper sulfate monohydrate per 100 gallons of bath or lbs. copper ammonium sulfate heptahydrate per lOO gallons of bath will produce coatings of high quality in the preferred weight range of from about 650 mg./ft to about 1.400 mgJft?
  • the source for chloride ion in the aqueous acidic coating solution can be any conveniently available water soluble chloride salt. Examples ofchloride salts which can be used are sodium chloride. potassium chloride and ammonium chloride.
  • the inhibitors employed in the process of the present invention are those which regulate the deposition of copper on the metal surface and control the acid attack on ferriferous surfaces.
  • Basic organic nitrogenous substances have proven to be most effective as inhibitors for copper coating processes.
  • the amount of the particular inhibitor in the concentrated formulations specified herein can vary from 0.5 to 3 percent by weight depending upon the strength of the inhibitor that is employed.
  • the inhibitor present in the coating will be depleted during operation of the process by such factors as dragout and Chemical breakdown. it is common practice to include the inhibitor in the replenishing admixture to replace the inhibitor loss.
  • the improved process of this invention is normally em ployed after cleaning of the metal surface has been accom plished.
  • the cleaning steps can be carried out by conventional methods which form no part of the present invention.
  • a conventional alkaline cleaner can be employed followed by a water rinse.
  • a detergent cleaner additive can be employed in the cleaning step.
  • scale or rust is present on the surface, a conventional pickling operation would be necessary followed by a water rinse.
  • the substrate is brought into contact with the aqueous acidic coating solution under suitable conditions of pH. temperature. and contact time.
  • the time of treatment of the metal surface with the coating solution need only be long enough to insure complete wetting of the surface and can be as long as 5 minutes.
  • contact time between the surface and the coating solution should range from about 1 minute to 5 minutes.
  • the coating solution is preferably applied by conventional immersion methods. ln certain specialized applications, spray or flow-coating techniques can be employed.
  • the coating solution should be maintained at a pH below 2.0.
  • the strong mineral acid employed to make up the initial aqueous acidulated solution should be selected from the group of sulfuric, phosphoric and nitric acid.
  • Hydrochloric acid can be employed as the strong mineral acid to make up the initial aqueous acidulated solution. Should hydrochloric acid be employed as the source of strong acid, the chloride ion present through addition of the acid must be taken into account when the makeup admixture is added to the aqueous acidulated solution. The use of hydrochloric acid is not preferred since it complicates the critical control of chloride ion concentration during the coating process.
  • the temperature at which the coating process can be operated is from about to about F. It is preferable to operate the coating bath at a temperature of from about l00 F. to about l50 F.
  • the treating solution can be prepared using a concentrated liquid admixture or a dry powder makeup formulation which, when added to an aqueous acidulated solution, will produce the operative bath with constituent concentrations within the preferred ranges.
  • the coating solution can be replenished with a concentrated admixture having constituents present in different proportions than the makeup material.
  • Formula 4 is presented as an example of such a concentrated admixture suitable for replenishing an operating coating bath.
  • EXAMPLE I The purpose of this work was to produced by a bath as a function of iron ion concentration in centrations. The results are illustrated in FIG. I.
  • FIG. 1 illustrates the effect and importance of chloride concentration on coating weight. It demonstrates that at a given ferrous ion concentration, coating weight will differ for each bath with different chloride concentrations. The coating baths are, therefore, not insensitive to wide variations of halide concentrations.
  • Formula A is a commonly used copper coating formulation.
  • Formula B is a copper-coating formulation where chloride product of orthotoluidine F. was maintained The panels were point at which the coating'produced by the-bath was nolonger acceptable requiring that the bath be dumped.
  • FIG. 3 plots coating weight produced during the coating operation as a func- Table 3 illustrates the quality and appearance ofthe coating produced during the coating operation.
  • the preceding results illustrate the importance of chloride control during a coating bath operation.
  • the makeup formulation. in this case Formula B must contain a specific quantity of chloride so that when used to prepare a bath and for replenishment. the rate at which chloride concentration will increase in the bath can be predetermined and controlled.
  • EXAMPLE lll Coating baths A and B were employed to demonstrate the longer bath life capability, in a practical application, when increasing chloride concentration is critically monitored. It can be observed from the following results that substantially increased bath life is obtained while equal or better quality coatings are maintained.
  • a 1,200 gal. coating bath (Bath A) was prepared with Formula A employed as the makeu material and replenishment material. 335 lbs. of Formula A were added to a bath at 2.5 percent B.V. H 50, and was operated at l20 F. Coating time was from about 2% min. to about 3 min. It was necessary to dump the bath when iron titration with O.l N potassium permanganate reached 4.8 ml., and ferrous ion concentration was 26.88 gram-ions/liter.
  • Another L200 gal. coating bath (Bath B) was prepared, with Formula B employed as the makeup and replenishment material. 250 lbs. of Formula B were added to a bath at 2.5 percent BM. H SO and was operated at 120 F. with a coating time from about 2 /2 min. to about 3 min. It was necessary to dump the bath when iron titration with 0.1 N potassium permanganate reached 7.3 ml, and ferrous ion concentration was 40.88 gram-ions/liter.
  • reaction product of orthotoluidinc H6. 4 plots chloride concentration as a function of the weight of steel coated during the operation of the respective baths.
  • the chloride control during the operation of Bath B enabled operation of the bath to continue for more than double the time, and the weight of metal coated was more than twice that coated by coating Bath A.
  • said coating solution consisting essentially of a copper salt selected from the group of copper sulfate monohydrate, copper sulfate pentahydrate, and copper ammonium sulfate heptahydrate, a basic organic nitrogenous inhibitor, a water-soluble chloride salt, and a strong mineral acid selected from the group of sulfuric, phosphoric and nitric acid, and wherein as the coating process continues iron is supplanted on the surface ofthe metal by an equivalent amount of copper thereby causing a steady increase in ferrous ion concentration in the acidic aqueous solution; the improvement which comprises increasing the life ofthe acidic aqueous solution by using as the makeup material for said coating solution a dry makeup admixture consisting essentially ofa copper salt, a basic organic nitrogenous inhibitor and a water soluble chloride salt which when added to an aqueous acidulated solution consisting essentially of water and a strong mineral acid selected from the group of nitric.
  • a dry makeup admixture consisting essentially of
  • sulfuric and phosphoric acid provides an aqueous acidic coating solution such that for each part by weight of copper in said coating solution there is present from about 0.1 to about b 0.6 parts by weight of chloride and the chloride ion concentration initially does not exceed 6 gram-ions/liter, and thereafter replenishing the said aqueous acidic coating solution by the periodic addition of sufficient amounts of a dry replenishing admixture consisting essentially of a copper salt, a basic organic nitrogenous inhibitor, and a water-soluble chloride salt, at a rate such that the chloride ion concentration in the aqueous acidic coating solution is increased by the addition of the dry replenishing admixture from 0.5 gram-ions/liter to 6 gram-ions/liter for each 5.6 gram-ions/liter increase in ferrous ion concentration.
  • a dry replenishing admixture consisting essentially of a copper salt, a basic organic nitrogenous inhibitor, and a water-soluble chloride salt

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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)
  • Paints Or Removers (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Chemically Coating (AREA)
US79101A 1970-10-08 1970-10-08 Chloride concentration control in immersion copper coating Expired - Lifetime US3649343A (en)

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JP (1) JPS5139178B1 (US07223432-20070529-C00017.png)
DE (1) DE2150080A1 (US07223432-20070529-C00017.png)
FR (1) FR2110311B1 (US07223432-20070529-C00017.png)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4563216A (en) * 1984-06-15 1986-01-07 Amchem Products, Inc. Compositions and processes for coating ferrous surfaces with copper
WO2012022660A1 (de) * 2010-08-17 2012-02-23 Chemetall Gmbh Verfahren zum stromlosen verkupfern von metallischen substraten
US11846026B2 (en) 2021-01-15 2023-12-19 General Electric Company Coated article for hot hydrocarbon fluid and method of preventing fuel thermal degradation deposits

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61183346U (US07223432-20070529-C00017.png) * 1985-05-04 1986-11-15

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2217921A (en) * 1938-03-23 1940-10-15 American Chem Paint Co Art of drawing ferrous metal

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2217921A (en) * 1938-03-23 1940-10-15 American Chem Paint Co Art of drawing ferrous metal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4563216A (en) * 1984-06-15 1986-01-07 Amchem Products, Inc. Compositions and processes for coating ferrous surfaces with copper
WO2012022660A1 (de) * 2010-08-17 2012-02-23 Chemetall Gmbh Verfahren zum stromlosen verkupfern von metallischen substraten
US11846026B2 (en) 2021-01-15 2023-12-19 General Electric Company Coated article for hot hydrocarbon fluid and method of preventing fuel thermal degradation deposits

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FR2110311B1 (US07223432-20070529-C00017.png) 1974-03-29
FR2110311A1 (US07223432-20070529-C00017.png) 1972-06-02
DE2150080A1 (de) 1972-04-13
JPS5139178B1 (US07223432-20070529-C00017.png) 1976-10-26

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Owner name: AMCHEM PRODUCTS, INC. A CORP. OF DEL.

Free format text: MERGER;ASSIGNORS:AMCHEM PRODUCTS, INC. (MERGED INTO);HHC, INC. (CHANGED TO);REEL/FRAME:004102/0461

Effective date: 19810320