Classifications

• • 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
  • C25D3/30—Electroplating: Baths therefor from solutions of tin
  • C25D3/32—Electroplating: Baths therefor from solutions of tin characterised by the organic bath constituents used
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/04—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
  • C07D233/06—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
  • C07D233/08—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms with alkyl radicals, containing more than four carbon atoms, directly attached to ring carbon atoms
  • C07D233/12—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms with alkyl radicals, containing more than four carbon atoms, directly attached to ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms
  • C07D233/14—Radicals substituted by oxygen atoms

Definitions

• An aqueous bath. for electroplating tin upon metal surfaces contains stannous ion, sulfate radical, a surfaceactive sulfated polyoxyalkyl carbinamine and an imidazoline derivative.
• the bath has a hydrogen ion concentration of about 0.9 to 4.1 grams per liter, and it operates effectively over a wide range of current densities to produce desirable deposits at relatively high plating rates.
• a variety of baths have been employed for electrodepositing tin upon metallic substrates, possibly the most widely used of which are the stannous fluoborate and caustic stannate solutions. Although these prior art baths have proven generally satisfactory and have been widely utilized, they are usually deficient in one or more desirable operating characteristics, and the deposits which they produce frequently fail to provide the levels of brightness, smoothness, ductility, adherance, solde-rability, porosity, or stability against ageing which are desired. Some of the baths are relatively expensive and many tend to be difiicult to maintain since fairly critical control of the concentrations of the components thereof is normally required. In addition, they often exhibit a tendency to be relatively slow and to operate properly only in fairly narrow ranges of current density.
• Another object is to provide a bath for electrodepositing tin at relatively high rates which is operable over a broad range of current densities.
• a specific object is to provide a convenient and rapid method for electroplating tin upon metallic workpieces utilizing an improved sulfate plating bath to obtain highly desirable tin deposits at relatively low cost.
• aqueous bath containing about 15.0 to 100.0 grams per liter of stannous ion, about 30.0 to 280.0 grams per liter of sulfate ion, about 0.5 to 6.0 grams per liter of a surface-active sulfated polyoxyalkyl carbinamine, and about 0.5 to 3.0 grams per liter of an imidazoline derivative.
• the hydrogen ion concentration of the bath should be maintained at about 0.9 to 4.1 grams per liter and the carbinamine and imidazoline are present in a ratio of their respective weights of about 0.753.0: 1.
• the imidazoline derivative included in the bath corresponds to the formula:
• R is an alkyl radical having 5 to 24 carbon atoms
• G is a radical selected from the group consisting of OH, acid salt radicals, anionic surface active sulfate salt radicals and anionic surface active sulfonate salt radicals;
• Z is a radical selected from the group consisting of COOM, CH COOM, and
• M is a substituent selected from the group consisting of hydrogen, alkali metals and organic bases;
• Y is selected from the group consisting of OR' and (6) each R substituent is independently selected from the group consisting of hydrogen, alkali metals, and (CH COOM;
• A is an anionic monovalent radical
• n is an integer from 1 to 4.
• the aqueous bath is prepared and maintained at a temperature of about to Fahrenheit.
• a workpiece having a metallic surface and a suitable anode are immersed in the bath and a voltage providing a current density of about 150 to 2000 amperes per square foot at the surface of the workpiece is applied across the anode and workpiece to deposit tin upon the latter.
• the baths of the present invention require the stannous ion, the sulfate radical, a surface-active sulfated polyoxyalkyl carbinamine, and an imidazoline derivative for proper operation.
• the stannous ion and the sulfate radical may be furnished to the bath by any combination of compounds suitable for use in tin plating solutions, but to avoid the presence of unnecessary and possibly interfering ions, these components are desirably introduced in the form of stannous sulfate and sulphuric acid.
• the former compound will provide both the stannous ion and the sulfate radical, whereas the latter compound provides additional sulfate radical which is present in the bath.
• the use of sulphuric acid is also desirable from the standpoint of control of the hydrogen ion concentration, although other acids providing non-interfering radicals may also be used for that purpose.
• Tin compounds other than stannous sulfate, e.g., stannous fiuoborate may be employed, but preferably they are used in conjunction with at least an equal weight of the sulfate compound.
• the amount of stannous ion present in the baths may vary between about 15.0 and 100.0 grams per liter, it is preferably about 35.0 to 80.0 grams per liter.
• the concentration of sulfate ion may normally be between about 30.0 and 280.0, it is preferably about 50.0 to 150.0 grams per liter.
• a broad range of about 0.9 to 4.1 grams per liter is suitable for the hydrogen ion concentration, it is most desirably maintained at about 1.0 and 3.0 grams per liter. If the concentration of stannous ion in the bath is too low, the efiiciency of plating and the quality of the deposit produced will be unsatisfactory.
• the surface-active carbinamine component In addition to the stannous ion and sulfate radical, the acid baths of the present invention require an effective amount of a combination of surface-active agents, one necessary member of which is an amphoteric sulfated polyoxyalkyl carbinamine which is stable under the conditions of plating.
• a combination of surface-active agents one necessary member of which is an amphoteric sulfated polyoxyalkyl carbinamine which is stable under the conditions of plating.
• carbinamines are produced by sulfating the terminal hydroxyl group on the polyoxyalkyl chain, and they may be in the form of an alkali metal salt thereof.
• R R and R are alkyl groups having a total of 7 to 23, and preferably 11 to 14, carbon atoms; m has a value of from 8 to 25, and preferably from 12.5 to 17.5; and X is a substituent selected from the class consisting of monovalent cations of hydrogen and of alkali metals.
• Surface active agents of this type are described in detail in U.S. Pat. No. 3,079,416, granted to Rohm & Haas Company on Feb. 26, 1963 as the assignee of John Dupre et al., and a particularly beneficial material is the sulfated polyoxyalkyl tertcarbinamine sold by Rohm & Haas under the trade name Triton QS-15.
• the baths preferably contain about 0.75 to 3.0 grams per liter. Not only is there insufficient benefit to justify the cost of using more than about 6 grams per liter of this material, but also higher amounts tend to produce dullness and roughness in the deposit. Use of less than about 0.5 gram per liter is generally found inadequate to produce the results desired. It will be appreciated that a combination of such carbinamines may be employed in a single bath, or combinations of the type disclosed in Boettner Pat. No.
• 3,079,348, assigned to Rohm & Haas Company may be r utilized beneficialally so long as the amount of the sulfated carbinamine is within the limits defined hereinbefore.
• Particularly good results have been obtained utilizing a combination of the sulfated polyoxyalkyl carbinamine (such as the Rohm & Haas QS15) and about 0.06 to 0.5 gram per liter of an amine polyglycol condensate (such as that sold by Rohm & Haas Company under the designation Triton CF-32).
• the indicated combination serves not only to provide a low foaming bath, but the bath is surprisingly effective in producing a tin deposit which is of increased brightness as compared to baths from which the amine polyglycol condensate is omitted.
• the imidazoline derivative The second essential component of the combination of surface-active agents is an imidazoline derivative corresponding to the formula:
• R represents an alkyl radical having to 24 carbon atoms
• G is OH ion, an acid salt radical, an anionic surface-active sulfate salt radical such 4 as preferably -OSO OR, or an anionic surface-active sulfonate salt radical
• Z is a --COOM, CH COOM,
• the substituent designated M in the foregoing formulae is a hydrogen atom, an alkali metal or an organic base, and that designated Y is either an -OR or N(R') A group.
• Each R substituent is independently selected from the group consisting of hydrogen, alkali metals, and (CH COOM; A represents an anionic monovalent radical and n represents an integer from 1 to 4.
• Use of the dotted line representation for the bonds connecting the substituents G and CH Z to the nitrogen atom indicates that the substituents are optionally present or absent, but it should be understood that'they are either both present or both absent.
• G represents the radical OSO OR, particularly in which R is a C to C alkyl group, and Z is a COOM radical in which M is preferably an alkali metal cation.
• Exemplary of the compounds corresponding to the foregoing formula which are satisfactory for use in the baths described herein are 2-alkyl-l-(ethyl-beta-oxypropanoic acid) imidazolines wherein the alkyl group is capryl, undecyl or a mixture of C -C chains, and the disodium salt of lauroyl-cycloimdinium-lethoxyethanoic acid-Z-ethanoic acid.
• the amount of the imidazoline constituent may be about 0.5 to 3.0 grams per liter of solution, it is preferably about 0.75 to 2.0 grams per liter. Less than about 0.5 gram per liter of this material is found to be relatively ineffective, whereas more than about 3.0 grams is economically undesirable and tends to produce dull, rough deposits. Regardless of the specific amounts of the carbinamine and imidazoline derivatives which are utilized, the ratio of their respective weights should be about 0.75 to 3.0:1, and most desirably the ratio therebetween will be about 1.0 to 2.0:-l.0.
• Exemplary of the brighteners which may be added are the aryl aldehydes, polyvinyl alcohol, gelatin, animal glue, evaporated milk, etc., and generally they will be added in a concentration of about 0.04 to 1.5 grams per liter. Brightness may also be enhanced by the inclusion of certain antioxidants, which also serve to reduce the tendency for insoluble precipitates to form in the bath. Such antioxidants include pyrocatechol, resorcinol and naphthol and may be employed in amounts of about 0.5 to 5.0, and preferably about 1.0 to 2.0 grams per liter. These additives are particularly effective in baths used at the higher plating rates in which the stannous ion concentration is relatively high.
• buffers, chelating agents and other additives commonly employed in baths of this type may also be included if desired.
• Chelating agents such as citric acid, malic acid, and the aminopolyacetic acids (i.e., ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid, nitriloacetic acid) are particularly beneficial to improve operation of the baths and to enhance the levels of brightness which may be obtained in the lower ranges of current density; they will normally be used in amounts of about 10.0 to 50.0 grams per liter.
• stannous ion, hydrogen ion, and sulfate radical concentrations specified herein are based upon the use of stannous sulfate and sulfuric acid, and that complete disassociation thereof is assumed. These factors should be borne in mind when determining the necessary amounts of other compounds which may be used in lieu thereof.
• the baths of the present invention are operable over a wide range of cathode current densities, and more specifically this range is about 150 to 2000 amperes per square foot (a.s.f.).
• the baths are preferably operated at current densities of about 200 to 1200 a.s.f. and, will be more fully described hereinafter, the concentrations of the components of the the baths may be varied considerably so as to obtain optimum results at the various current densities employed.
• the rate at which the tin is deposited is about 0.2 to 1.3 mils per minute; at the higher current densities, i.e., about 600 and 2000 a.s.f., plating occurs at a rate of about 1.3 to 3.8 mils per minute.
• plating efiiciency may be as high as 98 percent, based upon the theoretical rate of deposition.
• the baths which provide the best results at the lower current densities contain a relatively low concentration of stannous ion as compared to baths best operated in the higher ranges of current densities.
• Exemplary of the baths which are most suitable for use at about 150 to 600 a.s.f. is one which contains about 50.0 grams per liter of stannous ion, about 65.0 grams per liter of sulfate radical, about 0.75 gram per liter of the carbinamine and about 1.0 gram per liter of the imidazoline derivative, the hydrogen ion concentration therein being about 1.0 gram per liter.
• a chelating agent such as EDTA
• Exemplary of the baths which are most desirably operated at the higher current densities is one which contains about 75.0 grams per liter of stannous ion, about 110.0 grams per liter of sulfate radical, about 3.0 grams per liter of carbinamine, and about 1.5 grams per liter of the imidazoline derivative.
• This bath should have a hydrogen ion concentration of about 2.0 grams per liter; most desirably, it also contains about 2.0 grams per liter of pyrocatechol and about 0.06 gram per liter of an amine polyglycol condensate (such as Rohm & Haas Triton CF- 32).
• the baths should be operated at temperatures between about 75 and 150 Fahrenheit, and preferably about 90 to 120 Fahrenheit. Operation below about 75 Fahrenheit tends to be inefiicient and to produce undesirable deposits, whereas temperature higher than about 150 Fahrenheit tend to produce dull, rough and generally unacceptable deposits.
• the best temperature for operation of the bath of lower stannous ion concentration is about 100 Fahrenheit, whereas that for the bath of higher stannous ion concentration is about 120 Fahrenheit.
• the cathode i.e., the workpiece
• the cathode is moved relative to the bath at a high rate of speed. It will be appreciated that this may be accomplished by rotating the workpiece in the bath or by moving it linearly at a high rate of speed therethrough, such as in wire plating operations; it may also be achieved by agitating the bath or by rapid circulation thereof. Without such movement the deposits produced tend to be dark, spongy and poorly adherent, and, although the theory is not clearly understood, it is believed that this is due to the formation of a film about the cathode through which the stannous ion must diffuse.
• the relative motion tends to decrease the effect of such a cathode film barrier by eliminating it or by decreasing its thickness, thus facilitating movement of the ions to the cathode.
• the rate of relative movement may vary considerably, but most desirably the workpiece is moved relative to the bath at a linear rate equivalent to at least about 200 feet per minute. Rates as high as 800 feet per minute, and even higher, may be employed depending upon the characteristics of the bath and the workpiece, and the type of apparatu employed.
• Any metallic substrate or metal-surfaced article which can be plated with tin using prior art baths may be coated in accordance with the present invention. For example, good deposits of tin may be produced upon articles of copper, nickel, iron and steel.
• Filtration of the bath is not essential but is normally beneficial particularly when contamination is encountered from air-borne impurities and by carry-over from other operations.
• various filter media including fabrics, porous stoneware and other conventional materials may be utilized.
• the need for correction of the depletion of the various components of the bath is best determined by a periodic quantitative analysis for the several components, the frequency thereof being a function of the size of the bath and the plating rates employed.
• the baths are relatively low in cost and utilize additives which may be used in relatively non-critical ranges of concentration, so that they may be readily maintained in condition for proper operation.
• the baths and the components are easily stored as stable solutions, which may be readily prepared.
• An aqueous bath is prepared containing about grams per liter of stannous sulfate, about 45 grams per liter of sulfuric acid, about one gram per liter of 2-alkyl-1-(ethylbeta-oxypropanoic acid)-imidazoline, sold by Mona Industries, Inc. under the tradename Monateric CYA, and about 0.75 gram per liter of sulfated polyoxyalkyl tertcarbinamine, sold by Rohm and Haas under the tradename Triton QS-15; it has a hydrogen ion concentration of about 0.9 gram per liter.
• a cathode consisting of a length of copper wire and a pure tin anode are inunersed in the bath, which is heated to a temperature of about 80 Fahrenheit; the cathode is rotated in the bath at a rate equivalent to about 200 linear feet per minute.
• a voltage is applied across the anode and cathode to produce a current density of about 200 a.s.f. at the cathode and to cause tin to plate thereupon, the anode being of a size relative to the cathode sufficient to maintain the current density thereat below 80 a.s.f.
• the same bath is heated to a temperature of 120 Fahrenheit and a second wire anode is immersed along with a cathode which is rotated at a rate equivalent to about 600 linear feet per minute.
• the voltage applied is sufiicient to produce a cathode current density of about 400 a.s.f. and the relative size of the anode and cathode are suflicient to maintain the anode current density below 80 a.s.f.
• the deposits produced exhibit excellent adherence to the copper wire, and the ductility, solderability and resistance to ageing thereof are found to be good.
• the workpiece plated at a current density of 400 a.s.f. is tested in accordance with ASTM Method B-33 and found to be nonporous.
• EXAMPLE TWO A bath of the same composition as that prepared in accordance with Example One is prepared, with the sole exception that the 0.75 gram per liter of the carbinamine used therein is substituted with an equal weight of the imidazoline derivative specified so that the total amount of that compound in the bath amounts to 1.75 grams per liter. Plating with this bath under the conditions specified in Example One produces a deposit which is rough and streaked and which is generally unacceptable.
• a second bath is prepared comparable to the bath of Example One, the sole difference being that the quantity of imidazoline used therein is substituted by an equal weight of the carbinamine, so that the total amount of carbinamine contained in the bath is 1.75 grams per liter. Use of this bath under the conditions indicated in Example One results in a deposit which is very coarse and completely unacceptable.
• EXAMPLE THREE An aqueous bath is prepared as in Example One utilizing 120 grams per liter of stannous sulfate, about 45 grams per liter of sulfuric acid, about 1.0 gram per liter of the same carbinamine, and about 0.75 gram per liter of the same imidazoline derivative. This bath, maintained at a temperature of about 120 Fahrenheit and operated under cathode current densities of 1200 and 1800 a.s.f. produces semi-bright deposits upon a length of steel tubing one inch in diameter spun at 2250 rpm. during plating.
• Adding about 1.0 gram per liter of pyrocatechol to the bath increases the brightness of the deposit, and about 0.1 gram per liter of an amine polyglycol condensate (Rohm and Haas Triton (IF-32) enhances the brightness even further while also reducing the tendency for foaming the bath.
• IF-32 an amine polyglycol condensate
• EXAMPLE FOUR Baths similar to those prepared in accordance with Example Three are prepared, substituting about 40 grams per liter of the stannous sulfate used therein with an equal amount of stannous fiuoborate and utilizing lauroyl cycloimidinium-l-ethoxy ethanoic acid-2-ethanoic acid-disodium salt (Miranol C2M sold by Miranol Chemical Company) instead of the imidazoline derivative specified. In all instances the deposits obtained are of comparable quality.
• EXAMPLE FIVE An aqueous bath is prepared as in Example One by dissolving in water about 180 grams per liter of stannous sulfate, about 18 grams per liter of sulfuric acid, about 1.0 gram per liter of the same carbinamine, about 0.75
• Example One a gram per liter of the same imidazoline derivative and about 1.0 gram per liter of pyrocatechol.
• the bath is heated and operated as in Example One, with the exception that the voltage applied produces current densities of 900 to 1200 a.s.f. at the cathode; in each instance the temperature employed is Fahrenheit. Although dull deposits are obtained at both plating rates, they are very smooth; increasing the concentration of pyrocatechol to 3.0 grams per liter produces semi-bright deposits under the same conditions.
• the present invention provides a bath for producing a smooth, adherent and relatively non-porous deposit of tin which may in addition be bright or semi-bright.
• the bath is relatively inexpensive and is convenient to maintain since it does not require a high level of control of the concentration of the components thereof within critical limits.
• the bath may be used for depositing tin at relatively high rates and over a broad range of current density so as to aiford operating and economic advantages.
• An aqueous acid bath for producing an adherent electroplated tin deposit comprising about 15.0 to 100.0 grams per liter of stannous ion; about 30.0 to 280.0 grams per liter of sulfate radical; about 0.5 to 6.0- grams per liter of a surface-active sulfated polyoxyalkyl carbinamine; about 0.5 to 3.0 grams per liter of a surface-active imidazoline derivative; about 0.9 to 4.1 grams per liter of hydrogen ion, said carbinamine and imidazoline derivative being present in a ratio of their respective weights of about 0.75 to 3.0: 1.0.
• the bath of claim 1 comprising about 35.0 to 80.0 grams per liter of stannous ion, about 50.0 to 150.0 grams per liter of sulfate radical, about 0.75 to 3.0 grams per liter of said carbinamine and about 0.75 to 2.0 grams per liter of said imidazoline derivative, said ratio of carbinamine to imidazoline being about 1.0- to 2.0210, and the hydrogen ion concentration in said bath being about 1.0 to 3.0 grams per liter.
• R R and R are alkyl groups having a total of 7 to 23 carbon atoms, m is a number from 8 to 25 and X is a substituent selected from the class consisting of mono valent cations of hydrogen and of alkali metals.
• (l) R is an alkyl radical having 5 to 24 carbon atoms
• G is a radical selected from the group consisting of OH, acid salt radicals, anionic surface active sulfate salt radicals, and anionic surface active sulfonate salt radicals;
• Z is a radical selected from the group consisting of COOM, CH COOM, and
• M is a substituent selected from the group con sisting of hydrogen, alkali metals and organic bases;
• Y is selected from the group consisting of OR and N(R') A;
• each R substituent is independently selected from the group consisting of hydrogen, alkali metals, and (CH COOM;
• A is an anionic monovalent radical
• n is an integer from 1 to 4.
• said imidazoline derivative is selected from the group consisting of 2-alkyl-1- (ethyl-beta-oxypropanoic acid)-imidazolines wherein the alkyl group is selected from the class consisting of capryl, undecyl and mixtures of C C chains, and the disodium (salt) of lauroyl-cyclo-imidinium-l-ethoxy-ethanoic acid- 2- ethanoic acid.
• the bath of claim 1 additionally containing about 0.5 to 5.0 grams per liter of an antioxidant selected from the group consisting of pyrocatechol, resorcinol and naphthol.
• the bath of claim 1 additionally containing about 0.06 to 0.5 gram per liter of an amine polyglycol condensate brightening and defoaming agent.
• the bath of claim 1 additionally containing about 10.0 to 50.0 grams per liter of a chelating agent selected from the group consisting of malic acid, citric acid and aminopolyacetic acids.
• a chelating agent selected from the group consisting of malic acid, citric acid and aminopolyacetic acids.
• said imidazoline derivative has a structure wherein G is an anionic surfaceactive sulfate salt radical having the formula OSO OR in which sulfate salt radical R is an alkyl group containing 10 to 18 carbon atoms, and wherein Z is a COOM radical in which M is an alkali metal cation.
• (A) preparing an aqueous acid bath comprising about 15.0 to 100.0 grams per liter of stannous ion; about 30.0 to 280.0 grams per liter of sulfate radical; about 0.5 to 6.0 grams per liter of a surface-active sulfated polyoxyalkyl carbinamine; about 0.5 to 3.0 grams per liter of a surface-active imidazoline derivative; and about 0.9 to 4.1 grams per liter of hydrogen ion, said carbinamine and imidazoline derivative being present in a ratio of their respective weights of about 0.75 to 3.0: 1.0;
• said bath comprises about 35.0 to 80.0 grams per liter of stannous ion, about 50.0 to 150.0 grams per liter of sulfate radical, about 0.75 to 3.0 grams per liter of said carbinamine, about 0.75 to 2.0 grams per liter of said imidazoline derivative and about 1.0 to 3.0 grams per liter of hydrogen ion, said ratio of carbinamine to imidazoline being about 1.0 to 2021.0.
• R R and R are alkyl groups having a total of 7 to 23 carbon atoms, m is a number from 8 to 25 and X is a substituent selected from the class consisting of monovalent cations of hydrogen and of alkali metals.
• R is an alkyl radical having 5 to 24 carbon atoms
• G is a radical selected from the group consisting of OH, acid salt radicals, anionic surface active sulfate salt radicals, and anionic surface active sulfonate salt radicals;
• Z is a radical selected from the group consisting of COOM, CH COOM, and
• M is a substituent selected from the group consisting of hydrogen, alkali metals and organic bases;
• Y is selected from the group consisting of OR and N(R) A;
• each R substituent is independently selected from the group consisting of hydrogen, alkali metals, and (CH COOM;
• n is an integer from 1 to 4.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electroplating And Plating Baths Therefor (AREA)

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• 0
  • NL NL134759D patent/NL134759C/xx active
• 1968
  • 1968-10-16 US US768181A patent/US3575826A/en not_active Expired - Lifetime
• 1969
  • 1969-09-17 JP JP44073897A patent/JPS4924326B1/ja active Pending
  • 1969-10-10 NL NL6915347A patent/NL6915347A/xx unknown
  • 1969-10-16 GB GB50950/69A patent/GB1224966A/en not_active Expired
  • 1969-10-16 DE DE1952218A patent/DE1952218C3/de not_active Expired
  • 1969-10-16 FR FR6935494A patent/FR2020856A1/fr not_active Withdrawn

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