US3300335A - Electroless metal plating with foam - Google Patents

Description

United States Patent 3,300,335 ELECTROLESS METAL PLATING WITH FOAM Jack W. Horvath, Angleton, and Arthur C. Doumas, Lake Jackson, Tex., assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware No Drawing. Filed Nov. 20, 1963, Ser. No. 325,127 9 Claims. (Cl. 117130) This invention relates to an improved method for electroless plating of various materials, and more particularly to an electroless method utilizing a foamed plating solution.

Known methods of electroless plating usually require large excess amounts of solution per unit area of surface to be plated. For instance, when it is desired to plate the interior surface of a large vessel, the vessel usually must be filled with solution. The volume of solution required to fill the vessel is generally greatly in excess of the amount of solution required to give the desired plate, Because the life of most electroless plating solutions is usually not very long, the use of substantial excess amounts of solution can be extremely wasteful.

We have discovered a method wherein electroless plating may be accomplished employing a fraction of the volume of plating solution heretofore required. In accordance with our method, a quantity of a foaming agent, preferably from about 0.01 to about 1.0 percent by volume is added to the desired plating solution and a gas is then passed through the solution to become admixed with said solution thereby to form a foam. The foam is then applied to the basis material to be plated, spent solution and spent foam being removed after the desired plating is accomplished. In certain situations, such as plating large surface areas and the like, it may be desirable to continuously add new foam to the plating surface and withdraw spent solution and residual foam.

Suitable foaming agents are generally those which are not reactive with the plating metal or the basis material receiving the plate and do not form a precipitate with the bath. Water dispersa-ble soaps, common household detergents, and many other foama ble surfactants are generally satisfactory. Examples of some suitable foaming agents, to which the present invention is not limited, are sodium lauryl sulfate, organic salts of lauryl sulfate, sodium lauryl ethoxylated sulfate, nonyl phenol ethylene oxide adduct, fatty alcohol sodium sulfate, sodium dodecyl diphenyl oxide disulfonate, lauric diethanolamide, ethoxylated tridecyl alcohol, and the like.

Examples of some of the commercially available foaming agents, useful in the present invention are:

Trade Name Manufacturer Class and Formula Acetoquat CTAB Aceto Chemical Company Cetyl trimethyl ammonium bonnide.

CTAC do Cetyl trimethyl ammonium chloride.

ODAO Cctyl dimethyl benzylammonium chloride. Acetoquat CPO Cetyl pyridinium chloride.

CPB. do Cetyl pyridinium bromide. Aeidol 25A Onyx Chemical Corporation. Alkyl dimethyl amine acetate. Aerosol C-61 American Cyanamid Company. An ethanolated allgylguanidine amine complex. Alamine 4, 5, 6, 7, 11, 15, 21, 26, 1126, 33 General Mills, Inc Primary fatty amines, RNHz. Alamine 204, 205, 206, 207, 215, 221, H226". .do Secondary fatty amines, RQNH- Aliquat 204, 205, 206, 207, 215, 221, H226 ..do N-dllatty dimethyl quaternary ammonium Alkanol S Flakes. Amine E. I. du Pont de Nemours & Co Geigy Chemical Corporation Ony: Chemical Corporation o chlorides.

Sodium tetrahydronaphthalene sulfonate. Hetero cyclic tertiary amine,

Stearyl dimethyl benzyl annnonium chloride.

Cetyl dimethyl amine oxide. Cetyl dimethyl ethyl ammonium bromide.

Arquad 2HT-75 Arquad 28-75 Benax 2A1 Catanac SN Cerfak 1300 Comperlan l Comperlan LM Comperlan LP Comperlan RM Armour dz Company o The Dow Chemical Company American Cyauamid Company 0. L. King & Company Fallek Products Company Di-stearyl dimethyl ammonium chloride.

Di-soya dimethyl ammonium chloride.

Na Dodecyldiphenyl oxide disulfonate oxyethylated alkylphenols.

Stcaramido propyl di-methyl-B-hydroxy ethyl ammonium nitrate.

Fatty amido diarnine.

Alkyl polyoxyethylene thioether.

Coco fatty acid monoethanolamide.

Laurie acid monoethanolamide.

Laurie acid isopropanolamide.

Fatty acid ethanolamide.

Coco fatty acid polydiethanolamide.

Comperlan PD DBI O me Or anics Incorporated N-dodccyl benzyl N NN trimethyl ammonium chloride.

Dehyquart C Diam 21 Dichloran Dowfax 9N series Monamid l-L Monamid -M.

Fallek Products Company General Mills, Inc Fine Organics, Inc.

lhe Dow Chemical Company Fallek Products Company Hooker Chemical Corp Mon: Industries, Inc

Nalcamine G-l2 Nalco Chemical Co Sodium Vinyl Benzene Sulfona e Surfynol 61 Surtynol 82.

Rohm & Haas Co Air Reduction Chemical Co Tergitol 08 Union Carbide Chemicals Co Lauryl pyridinium chloride. N-fatty propylene diamine. Alkyl dimethyl diehlorobenzyl ammonium Trade Name Manufacturer Class and Formula Tergitol Ell .do

Wetting Agent F-126 acids, principally, perfiuoroeaprylie acid.

Gases appropriate for use in foaming the plating bath in accordance with the present invention are those which are not generally reactive with the plate metal, the material receiving the plate, or the plating bath. Usually, the relatively non-oxidizing gases such as hydrogen, carbon dioxide, nitrogen, the noble gases and, under most conditions air, are preferred.

Foaming is preferably accomplished by bubbling a gas, as described above, through the plating bath. Gas may be introduced to the bath by any suitable means, a sparge tube being one appropriate method. Other known means of foaming or frothing may be employed in addition to or in place of the preferred gas-foaming method, if desired.

Materials appropriately plated by the method of the present invention are those which are capable of being plated by electroless plating methods. Typical of such basis materials, but to which the present invention is not limited, are: metals, plastics, glass, quartz, wood, silicon carbide, porcelain, graphite, refractory materials, and the like.

Within the scope of the method of the present invention is included the use of any metal ion such as, for example, arsenic, cadmium, copper, gold, lead, nickel, silver, tin, rhodium, and a palladium, in any suitable electroless plating solution. The metal ion may be reduced by immersion plating in which the surface being plated is the reducing agent, or the metal ion may be reduced by a chemical reducing agent such as, forexample, sodium hypophosphite, formaldehyde, Rochelle salt, hydrazine, or an acid.

The following examples are set forth to further illustrate, and are not to be construed to limit, the present invention.

Example ].An aqueous plating bath was prepared having the following composition:

Grams per liter Sodium hypophosphite 20 Basic nickel carbonate Hydrofluoric acid (70% HF) 6 Citric acid 5.5 Ammonium acid fluoride Nonyl phenol ethylene oxide adduct 5 Steel coupons of dimensions of 2% inches by 4 inches by A inch and having'the nominal designation SAE 1020 were cleaned and pickled in percent HCl solution, then rinsed and dried.

Two liters of the above solution were poured into a container having dimensions 4 inches by 4 inches by 60 inches in height the solution being maintained at a temperature of from about 180 to 185 degrees Fahrenheit. Four of the steel coupons were suspended in the container above the solution. Air Was bubbled int-o the solution to produce a foam having sufficient height to cover the coupons.

After exposure of the coupons to the foam for about one hour, the coupons were removed from the container, rinsed, and examined. Asatisfactory coating of nickel had been deposited on each of the coupons.

Example 2.An aqueous plating bath was prepared having the following compositions:

Grams per liter Sodium hypophosphite 27 Nickel chloride 10 Sodium succinate 16 Lead chloride 0.004 Nonyl phenol ethylene oxide adduct 5 Coupons of SAE 1020 steel having the dimensions 1 inch by 4 inches by ,--inch were prepared as in Example 1 and placed in a long glass tube having a diameter of 1% inches. Foam was generated by bubbling hot air through the plating solution and passed through the tube. Temperature of the solution and foam varied from about 205 to about 210 degrees Fahrenheit. Solution was passed through the tube for a period of one hour and forty-five minutes.

After exposure to the foam for the above period, the coupons were removed from the glass tube, rinsed and examined. A satisfactory coating of nickel had been deposited on each coupon.

Example 3.- An aqueous plating bath was prepared having the following composition:

Grams per liter Sodium hypophosphite 27 Nickel chloride 20 Aminoacetic acid 15 Tetrasodium salt of ethylene diamine tetra acetic acid 8 Lead chloride 0.004 Sodium dodecyl diphenyl oxide disulfonate 5 Coupons of SAE 1020 steel of the size used in Example 2 were degreased, pickled, rinsed with a 2 percent solution of sodium salt of ethylene diamine tetraacetic acid, and dried. Employing substantially the method and solution of Example 2, except that nitrogen was the foaming gas, the coupons were exposed to foam individually in separate runs. The conditions were varied and the results tabulated as follows:

TABLE Trial N 0. Duration, Temperature, Thicknc ss,

Minutes Degrees F. Inches X10 Observation of the coupons after the coatings indicated that the nickel plating was uniform and free of pin holes and satisfactory in all respects.

Example 4.An 8-inch length of admiralty brass tube was degreased, pickled, and rinsed with a tetrasodium ethylene diamine tetraacetic acid solution. The length of brass tube was then immersed in an acid palladium chloride solution and rinsed thoroughly. Employing the method substantially as outlined in Example 2 and the bath of Example 3, foam at 180 degrees Fahrenheit was run through the tube for 2 /2 hours. The inside of the tube received a uniformly bright, electroless nickel coating 2.04 mils thick. The plate was uniform and free of pin holes.

Example 5.A graphite rod /2-inch in diameter and 4 inches long was was degreased with perchloroethylene, dipped in a stannous chloride solution, dipped in a palladium chloride solution, and thoroughly rinsed. Using substantially the method outline in Example 2 and the solution of Example 3, the graphite rod was exposed to plating foam, said foam having a temperature of about 180 degrees Fahrenheit, for a time of about /2-hour. A smooth, pin hole-free nickel coating 0.4 mil thick was deposited on the graphite rod.

Example 6.In substantially the same manner described above, arsenic, cadmium, copper, gold, lead, silver, tin, rhodium and palladium may be plated on suitable basis materials byernploying a conventional and appropriate electroless plating solution containing from about 0.01 to about 1.0 percent by volume of a foaming agent.

Various modifications may be made in the present invention without departing from the spirit or scope thereof, and it is to be understood that we limit ourselves only as defined in the appended claims.

We claim:

1. In a method wherein a basis material is plated with metal by contacting said basis material with an electroless plating solution, the improvement which comprises adding to said plating solution an amount of a foaming agent sufficient to permit foaming, foaming said solution, contacting the basis material with said foam, and removing spent solution from contact with the basis material.

2. In a method wherein a basis material is plated with metal by contacting said basis material with an electroless plating solution, the improvement which comprises adding to said plating solution from about 0.01 to about 1.0 percent by volume of a foaming agent, foaming said solution, contacting the basis material with said foam, and removing spent solution from contact with the basis material.

3. In a method wherein a basis material is plated with metal by contacting said basis material with an electroless plating solution, the improvement which comprises adding to said plating solution an amount of a foaming agent suificient to permit foaming, passing gas through said solution thereby to form a foam, contacting the basis material with said foam, and removing spent solution from contact with the basis material.

4. In a method wherein a basis material is plated with metal by contacting said basis material with an electroless plating solution, the improvement which comprises adding to said plating solution from about 0.01 to about 1.0 percent by volume of a foaming agent, passing gas through said solution, thereby to form a foam, contacting the basis material with said foam, and removing spent solution from contact with the basis material.

5. In a method wherein a basis material is plated with nickel by contacting said basis material with an electroless nickel plating solution, the improvement which comprises adding to said nickel plating solution from about 0.01 to about 1.0 percent by volume of a foaming agent, passing gas through said solution, thereby to form a foam, contacting the basis material with said foam, and removing spent solution from contact with the plated surface.

6. In a method wherein a steel surface is plated with nickel by contacting said steel surface with an electroless nickel plating solution, the improvement which comprises adding to said nickel solution from about 0.01 to about 1.0 percent by volume of nonyl phenol ethylene oxide adduct, passing air through said solution, thereby to form a foam, contacting the steel surface with said foam, and removing spent solution from contact with the plated surface.

7. In a method wherein a steel surface is plated with nickel by contacting said steel surface with an electroless nickel plating solution, the improvement which comprises adding to said nickel solution from about 0.01 to about 1.0 percent by volume of sodium do-decyl di phenyl oxide disulfonate, passing :air through said solution, thereby to form a foam, contacting the steel surface with said foam, and removing spent solution from contact with the plated surface.

8. In a method wherein a brass surface is plated with nickel by contacting said brass surface with an electroless nickel plating solution, the improvement which comprises adding to said nickel solution from about 0.01 to about 1.0 percent by volume of nonyl phenol ethylene oxide adduct, passing air through said solution, thereby to form a foam, contacting the brass surface with said foam, and removing spent solution from contact with the plated surface.

9. In a method wherein a graphite surface is plated with nickel by contacting said graphite surface with an electroless nickel plating solution, the improvement which comprises adding to said nickel solution from about 0.01 to about 1.0 percent by volume of nonyl phenol ethylene oxide adduct, passing air through said solution, thereby to form a foam, contacting the graphite surface with said foam, and removing spent solution from contact with the plated surface.

ALFRED L. LEAVITT, Primary Examiner.

R. S. KENDALL, Assistant Examiner.

Claims (1)

1. IN A METHOD WHEREIN A BASIS MATERIAL IS PLATED WITH METAL BY CONTACTING SAID BASIS MATERIAL WITH AN ELECTROLESS PLATING SOLUTION, THE IMPROVEMENT WHICH COMPRISES ADDING TO SAID PLATING SOLUTION AN AMOUNT OF A FOAMING AGENT SUFFICIENT TO PERMIT FOAMING, FOAMING SAID SOLUTION, CONTACTING THE BASIS MATERIAL WITH SAID FOAM, AND REMOVING SPENT SOLUTION FROM CONTACT WITH THE BASIS MATERIAL.