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US2678876A - Conditioning of metal surfaces - Google Patents

Conditioning of metal surfaces Download PDF

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Publication number
US2678876A
US2678876A US202827A US20282750A US2678876A US 2678876 A US2678876 A US 2678876A US 202827 A US202827 A US 202827A US 20282750 A US20282750 A US 20282750A US 2678876 A US2678876 A US 2678876A
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United States
Prior art keywords
metal
solution
copper
ammonium persulfate
mat finish
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Expired - Lifetime
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US202827A
Inventor
Don G Burnside
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RCA Corp
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RCA Corp
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Priority to US202827A priority Critical patent/US2678876A/en
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Classifications

    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
    • H05K3/382—Improvement of the adhesion between the insulating substrate and the metal by special treatment of the metal
    • H05K3/385—Improvement of the adhesion between the insulating substrate and the metal by special treatment of the metal by conversion of the surface of the metal, e.g. by oxidation, whether or not followed by reaction or removal of the converted layer

Definitions

  • This invention relates to the conditioning of metal surfaces and, more particularly, to improved processes of treating the surfaces of certain metals in order to both clean and roughen them.
  • the present invention is a method of cleaning and roughening a metal surface in a single-step chemical operation in order to obtain a mat finish.
  • the process comprises treating the metal surface, which is assumed to have been freed of any grease or oil, with a solution of ammonium persulfate containing a small per cent-age of hydrogen peroxide.
  • This solution has proven effective with metals such as copper, zinc, brass, cadmium, tin, alloys of copper and tin, and alloys of copper and nickel. It may also he applied to aluminum or magnesium or alloys of the two, if these metals are first treated with a solution of hydrofluoric acid.
  • One object of the present invention is to provide an improved process of conditioning metal surfaces to receive certain coating materials.
  • Another object of the invention is to provide an improved process of cleaning and roughening the surfaces of various metals in a single operation.
  • Another object of the invention is to provide an improved method of chemically abrading metal surfaces.
  • Another object of the invention is to provide all 2, an improved process of preparing metal surfaces for photoengraving or etching.
  • Another object of the invention is to provide a chemical method of obtaining a mat finish on various metals.
  • Still another object of the present invention is to provide an improvement in the process of forming a metal screen by the etching method.
  • Example 1 A polished brass plate which is to have a design applied to one of its surfaces by a process of photoengraving is first freed of any adhering oil or grease in conventional manner. This may be immersed in a solution consisting essentially of water, ammonium persulfate [(NI-I4)2S20s], and hydrogen peroxide.
  • the solution comprises the proportions of about 1 liter of water, 250 grams ammonium persulfate and 3 milliliters H202.
  • the hydrogen peroxide may be added as 1% by volume of the usual 30% aqueous solution of H202.
  • the brass sheet is permitted to remain in this solution for about 1 to 2 minutes at room temperature. It is then removed and rinsed with water to remove all residual traces of the treating solution ingredients.
  • the plate is then dried, preferably as rapidly as possible to avoid staining.
  • the surfaces of the brass sheet will 1 be found to have been given'a fine mat finish especially suitable to receive a light-sensitive gelatine emulsion of conventional type.
  • mat finish is meant one which is even and velvety but dull or lacking in luster.
  • the presence of the hydrogen peroxide in the treating solution is essential to obtain the desired roughening action on the metal surface.
  • the range of peroxide content may be from about .3% to 1.5% by volume.
  • a solution of ammonium persulfate alone will clean but not abrade.
  • a solution of hydrogen peroxide, alone will produce no roughening action on the metal. Both ingredients are necessary in combination to pro-- Jerusalem the abrading action and cleaning is accomplished at the same time.
  • the manner in which the persulfate and the peroxide cooperate to produce the abrading action is not understood. Morevoer, not all strong oxidizing agents are suitable to combine with the persulfate in this process since most of them attack the metal producing undesirable reaction products.
  • the time of treatment may be varied from about 1 minute to about 30 minutes.
  • the temperature may also be higher than room'temperature and is not critical. With higher temperatures, however, shorter treating times are required and the process is, somewhat more difficult to control.
  • the H202 also decomposes more rapidly at higher: temperatures; Room temperature is therefore preferred.
  • the concentration of ammonium persulfate can also-bevaried from about to about 40% by Weight, that is, from about 100-to 400 grams or ammonium persulfate per liter of water. Within this percentage-range, the treating time maybe" varied within'the time stated above, provided the solutions .are at room temperature.
  • the solution may be flowed over the' plate or an even film appliedby spraying.
  • Ezcample- 2 A sheet of aluminumwhich'is to have one'of its water-and the freshly exposed surface of thealuminum sheet is then treated'as described in Example l. By this process, the aluminum sheet is given a mat finish-suitable to receive a coating of bichromated gelatin.
  • Other metals which can be treated by this process are magnesium andany one of the many alloys of magnesium and aluminum.
  • the purpose of the additional pre-treatment with hydrofluoric acid is to remove the thin oxide layer which always forms on unprotected aluminum surfaces. Any conventional' method of removing theoxide, other than use of hydrofl'uoric acid, maybe used in this step.
  • a conventional method of making screens of this type is to coat a copper or brass plate with bichromated gelatin, expose the coated plate through a pattern of dots corresponding to the openings desired in the screen, Wash off the parts of the coating not exposed to light (the dots) and etch the metal thus exposed, entirely-through to the other surface.
  • the hardened portions of the gelatin sharply define limits of the holes and that the'coating of' gelatin adhere so well that none of the etching solution can flow beneath it, making ragged edges.
  • ammonium persulfate is present in the amount of about 25% by weight and the hydrogen peroxide is present in the amount of about 0.3% by volume.
  • a method 02 imparting a mat finish to a surface of a metal from the class consisting of aluminum, magnesium, and alloys consisting essentially of aluminum magnesium, the steps of removing the oxide film from said surface and then treating the freshly exposed surface of the metal with a solution consisting. essentially of Water, about. 10 to about 40% by weight ammonium persulfate, and about 0.3to 1.5% by volume'of hydrogen peroxide.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • ing And Chemical Polishing (AREA)

Description

Patented May 18, 1954 UNITED STAT. ATENT OFFICE CONDITIONING F METAL SURFACES 1 Don Burnside, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware 6 Claims.
This invention relates to the conditioning of metal surfaces and, more particularly, to improved processes of treating the surfaces of certain metals in order to both clean and roughen them.
Many processes utilizing sheet metals require the application of coating materials to the metal surfaces. Before the coating materials can be applied, the metal surfaces may have to be, first, carefully cleaned and then roughened somewhat so that the coating will adhere well. In a commonly used process of photoengraving or etching, for example, a coating of a light-sensitive emulsion is applied to the surface of a metal plate. To achieve successful application of the emulsion, it is necessary to clean the metal surface and abrade it slightly, producing a particular type of smooth, velvety, mat finish.
In the past, the surfaces of metal plates have been conditioned for photoengraving by cleaning with a solution of a material such as trisodium phosphate, and roughening by rubbing the surface with pumice powder. This produced a dull surface having a large number of hair-line scratches per inch. Although this method has proved successful and has become Widely used, the process obviously necessitates use of two distinct steps of cleaning and abrading, with the latter being a somewhat time-consuming mechanical operation, even when done with a rotating polishing wheel.
The present invention is a method of cleaning and roughening a metal surface in a single-step chemical operation in order to obtain a mat finish. The process comprises treating the metal surface, which is assumed to have been freed of any grease or oil, with a solution of ammonium persulfate containing a small per cent-age of hydrogen peroxide. This solution has proven effective with metals such as copper, zinc, brass, cadmium, tin, alloys of copper and tin, and alloys of copper and nickel. It may also he applied to aluminum or magnesium or alloys of the two, if these metals are first treated with a solution of hydrofluoric acid.
One object of the present invention is to provide an improved process of conditioning metal surfaces to receive certain coating materials.
Another object of the invention is to provide an improved process of cleaning and roughening the surfaces of various metals in a single operation.
Another object of the invention is to provide an improved method of chemically abrading metal surfaces.
Another object of the invention is to provide all 2, an improved process of preparing metal surfaces for photoengraving or etching.
Another object of the invention is to provide a chemical method of obtaining a mat finish on various metals.
Still another object of the present invention is to provide an improvement in the process of forming a metal screen by the etching method.
These and other objects will be more apparent and the invention will be more readily understood from the following detail description:
Example 1 A polished brass plate which is to have a design applied to one of its surfaces by a process of photoengraving is first freed of any adhering oil or grease in conventional manner. This may be immersed in a solution consisting essentially of water, ammonium persulfate [(NI-I4)2S20s], and hydrogen peroxide. The solution comprises the proportions of about 1 liter of water, 250 grams ammonium persulfate and 3 milliliters H202. The hydrogen peroxide may be added as 1% by volume of the usual 30% aqueous solution of H202. The brass sheet is permitted to remain in this solution for about 1 to 2 minutes at room temperature. It is then removed and rinsed with water to remove all residual traces of the treating solution ingredients. The plate is then dried, preferably as rapidly as possible to avoid staining. The surfaces of the brass sheet will 1 be found to have been given'a fine mat finish especially suitable to receive a light-sensitive gelatine emulsion of conventional type. By mat finish is meant one which is even and velvety but dull or lacking in luster. When the treated plate is examined microscopically, the mat appearance is found to be due to the formation of a multitude of tiny projecting crystals.
The presence of the hydrogen peroxide in the treating solution is essential to obtain the desired roughening action on the metal surface. The range of peroxide content may be from about .3% to 1.5% by volume. A solution of ammonium persulfate alone will clean but not abrade. Also, a solution of hydrogen peroxide, alone, will produce no roughening action on the metal. Both ingredients are necessary in combination to pro-- duce the abrading action and cleaning is accomplished at the same time. The manner in which the persulfate and the peroxide cooperate to produce the abrading action is not understood. Morevoer, not all strong oxidizing agents are suitable to combine with the persulfate in this process since most of them attack the metal producing undesirable reaction products.
The process of: which the aboveexample is a typical preferred embodiment may be applied in the same manner to sheets of other metals such as copper, alloys of copper and nickel, such as that containing 70% copper and 30% nickel, cadmium, and tin, also any of the copper-tin alloys.
The time of treatment may be varied from about 1 minute to about 30 minutes. The temperature may also be higher than room'temperature and is not critical. With higher temperatures, however, shorter treating times are required and the process is, somewhat more difficult to control. The H202 also decomposes more rapidly at higher: temperatures; Room temperature is therefore preferred.
The concentration of ammonium persulfate can also-bevaried from about to about 40% by Weight, that is, from about 100-to 400 grams or ammonium persulfate per liter of water. Within this percentage-range, the treating time maybe" varied within'the time stated above, provided the solutions .are at room temperature.
Insteadofimmersing the-platein the treatingsolution, the solution may be flowed over the' plate or an even film appliedby spraying.
Ezcample- 2 A sheet of aluminumwhich'is to have one'of its water-and the freshly exposed surface of thealuminum sheet is then treated'as described in Example l. By this process, the aluminum sheet is given a mat finish-suitable to receive a coating of bichromated gelatin. Other metals which can be treated by this process are magnesium andany one of the many alloys of magnesium and aluminum. The purpose of the additional pre-treatment with hydrofluoric acid is to remove the thin oxide layer which always forms on unprotected aluminum surfaces. Any conventional' method of removing theoxide, other than use of hydrofl'uoric acid, maybe used in this step.
Use'of the solutions and the methods of the present invention produce surfaces on metals which are especially adapted'to be processed into screens having a large number of holes per square inch; In order to make screenssuitable foroptical. equipment, the holesmust'be uniform insize and regular in outline: A conventional method of making screens of this type is to coat a copper or brass plate with bichromated gelatin, expose the coated plate through a pattern of dots corresponding to the openings desired in the screen, Wash off the parts of the coating not exposed to light (the dots) and etch the metal thus exposed, entirely-through to the other surface. To make a screen of good optical quality by this method, it is necessary that the hardened portions of the gelatin sharply define limits of the holes and that the'coating of' gelatin adhere so well that none of the etching solution can flow beneath it, making ragged edges.
I claim as myinvention:
1. In a method'of imparting a mat finish to a polishedsurface ofa metal of the class consisting of copper and brass, the steps of treating said surfacewith a solution consisting essentially of water, about 10-40% byv weight of ammonium persulfate, and about 0.3 to about 1.5% by volume of hydrogen peroxide, and continuing said treatment until said mat finish has been formed.
2. A method according to claim 1 in which the ammonium persulfate is present in the amount of about 25% by weight and the hydrogen peroxide is present in the amount of about 0.3% by volume.
3. A method according to claim 1 in which said metal is brass.
4. A method according to claim 1 in whichsaid metal is copper.
5. In a method 02 imparting a mat finish to a surface of a metal from the class consisting of aluminum, magnesium, and alloys consisting essentially of aluminum magnesium, the steps of removing the oxide film from said surface and then treating the freshly exposed surface of the metal with a solution consisting. essentially of Water, about. 10 to about 40% by weight ammonium persulfate, and about 0.3to 1.5% by volume'of hydrogen peroxide.
6. In a method of imparting a mat finish to a polished surface of a metal of the'class consisting of aluminum, magnesium and alloys of aluminum and'magnesium, the steps of treating said sur face with a solution consisting essentially of water, about'10- i0% by weight of ammonium persulfate, and about 0.3 to about 1.5% by volume of hydrogen peroxide, and'continuing said treatmentuntil said mat finish has been formed.
References Cited in the file of this patent- UNITED STATES PATENTS- Number Name Date 2,000,576 Boller May 7, 1935 2,154,455 Kepfer Apr. 18, 1939 2,409,271 Goldowski Oct. 15, 1946

Claims (1)

1. IN A METHOD OF IMPARTING A MAT FINISH TO A POLISHED SURFACE OF A METAL OF THE CLASS CONSISTING OF COPPER AND BRASS, THE STEPS OF TREATING SAID SURFACE WITH A SOLUTION CONSISTING ESSENTIALLY OF WATER, ABOUT 10-40% BY WEIGHT OF AMMONIUM PERSULFATE, AND ABOUT 0.3 TO ABOUT 1.5% BY VOLUME OF HYDROGEN PEROXIDE, AND CONTINUING SAID TREATMENT UNTIL SAID MAT FINISH HAS BEEN FORMED.
US202827A 1950-12-26 1950-12-26 Conditioning of metal surfaces Expired - Lifetime US2678876A (en)

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2942954A (en) * 1955-10-20 1960-06-28 Gen Motors Corp Non-hazardous etching solutions
US2982625A (en) * 1957-03-22 1961-05-02 Sylvania Electric Prod Etchant and method
US3125474A (en) * 1964-03-17 Pickling zirconium and zirconium base alloys
US3137600A (en) * 1960-09-12 1964-06-16 Fmc Corp Dissolution of copper
US3140203A (en) * 1961-04-24 1964-07-07 Macdermid Inc Method of and composition for treating aluminum and aluminum alloys
US3193423A (en) * 1962-09-25 1965-07-06 Goffredo Daniel Louis Etching printing plates
US3281293A (en) * 1963-07-19 1966-10-25 Chemcut Corp Method of etching aluminum
US3476624A (en) * 1966-02-08 1969-11-04 Fmc Corp Process of etching copper circuits
US3954498A (en) * 1974-10-03 1976-05-04 Motorola, Inc. Aluminum foil cleaning process
US4076564A (en) * 1974-09-16 1978-02-28 Xerox Corporation Roughened imaging surface for cleaning
US4754803A (en) * 1987-02-02 1988-07-05 Phelps Dodge Industries, Inc. Manufacturing copper rod by casting, hot rolling and chemically shaving and pickling
US4946520A (en) * 1987-02-02 1990-08-07 Phelps Dodge Industries, Inc. Copper rod manufactured by casting, hot rolling and chemically shaving and pickling
US5052421A (en) * 1988-07-19 1991-10-01 Henkel Corporation Treatment of aluminum with non-chrome cleaner/deoxidizer system followed by conversion coating
WO2004027120A1 (en) * 2002-09-17 2004-04-01 Omg Galvanotechnik Gmbh Dark layers

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2000576A (en) * 1934-03-01 1935-05-07 Grasselli Chemical Co Mordant
US2154455A (en) * 1934-02-08 1939-04-18 Du Pont Cadmium bright dip
US2409271A (en) * 1943-03-22 1946-10-15 Welding Research Inc Process for cleaning aluminum

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2154455A (en) * 1934-02-08 1939-04-18 Du Pont Cadmium bright dip
US2000576A (en) * 1934-03-01 1935-05-07 Grasselli Chemical Co Mordant
US2409271A (en) * 1943-03-22 1946-10-15 Welding Research Inc Process for cleaning aluminum

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3125474A (en) * 1964-03-17 Pickling zirconium and zirconium base alloys
US2942954A (en) * 1955-10-20 1960-06-28 Gen Motors Corp Non-hazardous etching solutions
US2982625A (en) * 1957-03-22 1961-05-02 Sylvania Electric Prod Etchant and method
US3137600A (en) * 1960-09-12 1964-06-16 Fmc Corp Dissolution of copper
US3140203A (en) * 1961-04-24 1964-07-07 Macdermid Inc Method of and composition for treating aluminum and aluminum alloys
US3193423A (en) * 1962-09-25 1965-07-06 Goffredo Daniel Louis Etching printing plates
US3281293A (en) * 1963-07-19 1966-10-25 Chemcut Corp Method of etching aluminum
US3476624A (en) * 1966-02-08 1969-11-04 Fmc Corp Process of etching copper circuits
US4076564A (en) * 1974-09-16 1978-02-28 Xerox Corporation Roughened imaging surface for cleaning
US3954498A (en) * 1974-10-03 1976-05-04 Motorola, Inc. Aluminum foil cleaning process
US4754803A (en) * 1987-02-02 1988-07-05 Phelps Dodge Industries, Inc. Manufacturing copper rod by casting, hot rolling and chemically shaving and pickling
US4946520A (en) * 1987-02-02 1990-08-07 Phelps Dodge Industries, Inc. Copper rod manufactured by casting, hot rolling and chemically shaving and pickling
US5052421A (en) * 1988-07-19 1991-10-01 Henkel Corporation Treatment of aluminum with non-chrome cleaner/deoxidizer system followed by conversion coating
WO2004027120A1 (en) * 2002-09-17 2004-04-01 Omg Galvanotechnik Gmbh Dark layers

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