US 4,071,415 A · Method of electroplating aluminum and its alloys

Abstract

Aluminum or an alloy thereof is electroplated upon electrically conductive substrates by immersing the substrate as a cathode in a novel stable electrolyte, made as follows: A. reacting aluminum with a hydrogen halide such as HCl, HBr, or HI (but preferably hydrogen bromide) or reacting aluminum with a halogen such as Cl.sub.2, Br.sub.2, or I.sub.2 (but preferably bromine), in the absence of water, but in one of the following single organic, non-Lewis base solvents or mixtures thereof: benzene, toluene, carbon disulfide, cyclohexane, dimethyl sulfide, tetrahydrofuran, diiodoethane, toluene-cyclohexane (1:1), benzene-cyclohexane (1:1), tetrahydrofuran (THF): benzene (4:1) and toluene-CS.sub.2 (3:1) to form an intermediate aluminum halide cation in solution, the concentration of the aluminum cation and the concentration of hydrogen ion, in solution being respectively, below about 7.5 M and 0.5 M and preferably being, respectively, below about 4.2 M and 0.1 M; and B. then adding a restricted amount, preferably less than about 16 mole % relative to the initial quantity of aluminum added, of a metal halide, MX where M=Li, Na, or K and X=Cl, Br, or I; or where MX is a special halide such as beryllium bromide, magnesium bromide, or quaternary ammonium bromide to form a different, stable aluminum-cationic plating species. The novel electrolyte is then directed to a plating chamber, utilized in the plating chamber until it is aluminum ion poor, transferred to a regeneration chamber, filtered and returned to the plating chamber for further plating operations.

Claims23

Dependent claims

In a continuous plating process, the steps of:

a. forming a fresh electroplating solution containing an aluminum cationic plating species;
b. transferring said fresh electroplating solution to a plating cell;
c. depositing aluminum onto a cathodic substrate within said plating cell at low voltages on the order of less than five volts to produce an electroplating solution which is aluminum-cation poor;
d. transferring said aluminum-cation poor electroplating solution to a regeneration zone including activated aluminum for reaction of said aluminum-cation poor electroplating solution with said activated aluminum to produce an enriched electroplating solution, having an aluminum cationic plating species with an aluminum ion molarity greater than that of said aluminum-cation poor electroplating solution;
and
e. returning said thusly enriched electroplating solution, to said plating cell for further plating of aluminum therefrom.

3 more elements

In a continuous plating process, the steps of:

a. forming a fresh electroplating solution by
reacting a given quantity of aluminum, in the presence of an organic, substantially anhydrous, non-Lewis base solvent, with
i. a member of the group consisting essentially of a halogen and a hydrogen halide in a quantity in excess of that required to produce an aluminum halide but below that required to produce a hydrogen ion concentration of less than about 0.5 molar, and with (ii) about 0.5 - 20 mole % metallic halide, based on the initial mole quantity of said aluminum, said metallic halide being selected from the group consisting of the halides of Lithium, Sodium, Potassium, Beryllium, Magnesium and the Ammonium ion, to form a plating solution containing an aluminum cationic plating species having an aluminum ion molarity of below about 7.5 molar;
b. transferring said fresh electroplating solution to a plating cell;
c. depositing aluminum onto a cathodic substrate within said plating cell at low voltages, on the order of less than five volts, to produce an electroplating solution that is aluminum-cation poor;
d. transferring said aluminum-cation poor electroplating solution to a regeneration zone including activated aluminum for reaction of said aluminum-cation poor electroplating solution with said activated aluminum to produce an enriched electroplating solution, having an aluminum cationic plating species with an aluminum ion molarity substantially greater than that of said aluminum-cation poor electroplating solution;
and
e. returning said thusly enriched electroplating solution, to said plating cell for further plating of aluminum therefrom.

5 more elements

Dependencies are inferred from the claim text.

Method of electroplating aluminum and its alloys

Life of this patent

Method of electroplating aluminum and its alloys

Life of this patent

Abstract

Claims23