US2839456A

US2839456A - Electroplating

Info

Publication number: US2839456A
Application number: US622529A
Authority: US
Inventors: Foulke Donald Gardner; Kardos Otto
Original assignee: Hanson Van Winkle Munning Co
Current assignee: Hanson Van Winkle Munning Co
Priority date: 1956-11-16
Filing date: 1956-11-16
Publication date: 1958-06-17
Anticipated expiration: 1975-06-17

Description

2,839,456 Patented June 17, 1958 ELECTROPLATIN G Donald Gardner Foulke, Watchung, and Otto Kardos,

Red Bank, N. J., assignors to Hanson-Van Winkle- Munning Company, a corporation .of New Jersey No Drawing. Application November 16, 1956 Serial No. 622,529

6 Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepositing nickel from an acidic nickel plating bath. The invention is based on our discovery that 2-(4-pyridyl) ethyl sulfonic acid, and certain of its salts, when incorporated in a nickel electroplating bath in combination with various sulfo-oxygeu compounds, is capable of producing excellent bright ductile nickel electrodeposits over a wide current density range. We have found that in all instances the combined use of 2-(4-pyridyl) ethyl sulfonic acid and the sulfo-oxygen compound exerts a synergistic effect on the brightening capacity of the bath as compared with the use of either compound alone.

A preferred process according to this invention for producing bright nickel deposits comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt, in which there is dissolved from about 0.1 to about 10 grams per liter of 2-(4-pyridyl) ethyl sulfonic acid or an alkali metal, magnesium, ammonium, or nickel salt thereof, together with from about A to about 80 grams per liter of a water-soluble sulfo-oxygen compound of the group consisting of mononuclear and binuclear aromatic sulfonic acids, mononuclear aromatic sulfinic acids, the alkali metal, magnesium, ammonium,

and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides.

The compounds listed in Table I are examples of sulfo-oxygen compounds which, when used in combination with 2-(4-pyridyl) ethyl sulfonic acid and its abovementioned salts, promote the formation of brilliant and ductile nickel deposits. These sulfo-oxygen compounds may be used over a wide range of concentrations 4 to 80 grams per liter), but preferably are used in an amount in the range from about 1 to 20 grams per liter.

TABLE I Organic sulfa-oxygen compounds (1) Unsaturated aliphatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Sodium vinyl sulfonate, H C=CHSO Na Sodium allyl sulfonate, H C=CHCH SO Na (2) Mononuclear aromatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Benzene monosulfonic acid, C H SO H Sodium benzene monosulfonate, C H SO Na Nickel benzene mouosulfonate, (C H SO Ni Sodium p-toluene monosulfonate, CH C H SO Na p-Chlorobenzene sulfonic acid, ClC H SO I-I Sodium p-chlorobenzene sulfonate, ClC H,SO Na Sodium p-bromobenzene sulfonate, BrC H SO Na 1,2-dichlorobenzene sulfonic acid, Cl C H SO H 1,2- or 2,5-dichlorobenzene sulfonates, sodium salt,

m-Benzene disulfonic acid, C H (SO H) Sodium m-benzene disulfonate, C H (SO Na) 2 Nickel m-benzene disulfonate, C H (SO Ni o-Sulfobenzoic acid monoammonium salt,

l-amino-2,5-benzene disulfonic acid, H NC H (SO H) o-Aminobenzene sulfonic acid, H NC H SO H (3) Mononuclear aromatic sulfinic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Sodium benzene sulfinate, C H SO Na Sodium p-toluene sulfinate, CI-I C H SO Na.

(4) ltlononuclear aromatic sulfonamides and sulfonimides Benzene sulfonamide, C H SO NH p-Toluene sulfonamide, CH C H SO NH o-Sulfobenzoic imide CaHiC ONHSOZ Benzyl sulfonamide, C H CH SO NH Benzene sulfhydroxamic acid, C H SO NHOH N,N-dimethylp-toluene sulfonamide,

CH C H SO N(CH N,N-dicarboxyethyl benzene sulfonamide,

C H SO N(C H COOH) (5)Binuclear aromatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

(6) Heterocyclic sulfonic acids, and alkali metal, ammonium, magnesium, andlnickel salts thereof:

Thiophene sulfonic acid, C H S SO H Sodium thiophene sulfonate, C H S-SO Na ,For the most part, only free sulfonic acids are listed in Table I. However, the alkali metal, ammonium, magnesium, and nickel salts are in all cases thetfull equivalent of the acids, and may be used in their place in carrying out the process of this invention. i

Brightener additions according to this invention have, of course, been used successfully in the standard Watts nickel electroplating bath. However, these brightener additions are also efifective in all other acid. nickel electroplating baths, and consequently the invention is applicable to any nickel electrodeposition from an aqueous acidic solution of one or more nickel salts.

To illustrate the applicability of using 2-(4-pyridyl) ethyl sulfonic acid in diiferent nickel electroplating baths under a variety of conditions, Table II lists the basic compositions of several types of plating baths which were employed in carrying out the examples of the invention that are set forth below.

TABLE II Bath concentrations in grams per liter Bath A Bath 0 Bath 0 Nickel sulfate l 300 Nickel chloride. Nickel sulfamata Nickel fluoborate Boric acid In each of the following examples of the invention, the electrodeposit was formed in a Hull test cell on brass cathodes so that the effect of a wide range of current densities could be observed. The pH of the bath was adjusted to about 3.5 to 4 inxeach case, and the electrodeposit was formed at a temperature of 50 C.

EXAMPLE I To the'Watts bath (bath A) described in Table II were added 2 grams .per liter'of sodium 2-(4-pyridy'l) ethyl sulfonate. After adjusting the voltage through the Hull test cell to give a total current of two amperes, the test panel received a nickel electroplate which was only fairly bright over the lower 70 percent of the entire current density range.

In a comparative operation, 0.3 gram per liter of so dium 2-(4-pyridyl) ethyl sulfonate and 16 grams per liter of sodium 1,3,6-naphthalene triisulfonate were added to a freshly prepared plating solution having the composition of bath A. Again at a total current of two amperes, the nickel electroplate formed on the panel was very bright, over the entire current density range, and distinctly brighter than the control panels plated from a Watts bath containing 16 grams per liter of the trisulfonate alone. Increasing the concentration of sodium 2-(4-.pyridyl) ethyl sulfonate to 0.6 and 0.8 gram per liter in a bath also containing the naphthalene trisulfonate substantially increased the brightness of the electroplate.

EXAMPLE II As a general rule, the synergistic effect of 2-(4-pyridyl) ethyl sulfonic acid on the brightening capacity of sulfooxygen compounds is most pronounced at high current densities. The test panel of a Hull cell received a nickel electrodeposit from bath A which contained 4 grams per liter of sodium benzene sulfonate. Although the plated panel was fairly bright in the central and lower current density ranges, it was streaked and matted at the upper current density range. By adding 1 gram per liter of sodium 2-(4-pyridyl) ethyl sulfonate to the electroplating solution, the nickel dcposit became very bright over substantially the entire current density range. Increasing the sodium benzene sul'fonate to 8 grams per liter had no eitect on the brightness, but improved the ductility of the electrodeposit.

EXAMPLE III Brilliant nickel deposits are formed when the 1pyridyl ethyl sulfonic acid is used in conjunction with aromatic sulfonamides or sulfonimides. Table III sets forth in detail the results achieved when nickel is electrodeposited Sulfo-Oxygen Compound (2 grams/liter) Sodium 2- i-pyridyl) ethyl Results sulionate (grams/liter) Very bright. Brilliant and ductile.

Do. Very bright with no brittleness.

o-Sulfobenzoic imide Benzene sulfonamidc Benzyl sulfonamide EXAMPLE IV To a sulfamate nickel plating bath (bath B), which had been properly purified, was added 1.6 grams per liter of sodium Z M-pyridyl) ethyl sulfonate, and nickel electrodeposited on a Hull test panel. The deposit was brittle and moderately bright over only the lower 60 percent of the test panel. Increasing the sodium 2-(4- 'pyridyl) ethyl sulfonate to 3.2 grams per liter did not increase the brightness nor extend the range. Upon the addition of 15 grams per liter of sodium 1,3,6-naphthalene trisuiionate to this bath, the brightening range was markedly extended, and the brittleness of the deposit reduced.

When 15 grams per liter of sodium 1,3,6-naphthalenc trisulfonate were added to a plating solution of the same basic composition but not containing the ethyl sulfonate, the deposit was only semi-bright over a wide current density range with a strong haze at the middle and low current densities. Addition of 0.4 to 0.8 gram per liter of 2-(4-pyridyl) ethyl sulfonic acid to this bath strongly reduced this haze.

EXAMPLE V Using a nickel fiuoborate bath (bath C) which had een previously purified, the electrodeposition of nickel from such bath at 50 C. and at a pH of about 3.0 in 8. Hull cell was scarcely affected by adding 3.2 grams per liter of Z-( i-pyridyl) ethyl sulfonic acid to the bath. The useof 15 grams per liter of sodium 1,3,6-naphtha1ene trisultonate alone in the same iluoborate bath produced only a hazy semi-brightness. When, however, both 15 grams per liter of sodium 1,3,6-naphthalene trisulfonate and 1.6 grams per liter of sodium 2-(4-pyridyl) ethyl sulfonate Were combined in a freshly prepared nickel fluoborate bath, the resulting nickel deposits were bright over a Wide current density range.

Although the examples have, for the most part, illustrated the use of sodium 2-(4-pyridyl) ethyl sulfonate, or the free acid, the remaining alkali metal, ammonium,

' magnesium and nickel salts of this acid are fully equivalent, and may be used to carry out the process of this invention.

The synergistic effect of 2-(4-pyridyl) ethyl sulfonic acid, or its aforementioned salts, may be obtained by using concentrations as low as 0.1 gram per liter in the plating bath. Although concentrations in excess of 10 grams per liter may be employed, there is no particular advantage to be gained from the higher concentrations.

We claim:

1. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 grams per liter of a heterocyclic organic compound of the group consisting of 2-(4-pyridyl) ethyl sulfonic acid and the alkali metal, magnesium, ammonium, and nickel salts thereof, and from about A to about 80 grams per liter of a watersoluble sulfo-oxygcn compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, mononuclear aromatic sulfinic acids, the alkali metal, magnesium, ammonium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides.

2. The method according to claim 1, in which the concentration of the sulfo-oxygen compound is in the range from i to 20 grams per liter.

3. The process for producting bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 10 grains per liter of a heterocyclic organic compound of the group consisting of 2-(4-pyridyl) ethyl sulfonic acid and the alkali metal, magnesium, ammonium, and nickel salts thereof} and from about /4 to about 20 grams per liter of o-sulfobenzoic imide. I

4. An aqueous acidic nickel electroplating bath in which there is dissolved from about 0.1 to about 10 grams per liter of a heterocyclic organic compound of the group consisting of 2-(4-pyridyl) ethyl sulfonic acid and the alkali metal, magnesium, ammonium, and nickel salts thereof, and from about to about 80 grams per liter of a Water-soluble sulfo-oxygen compound of the group consisting of-unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, mononuclear aromatic sulfinie acids, the alkali metal, magnesium, ammonium, and nickel salts of said acids, and mononuclear aromatic sulfonarnides and sulfonimides.

5. An aqueous acidic nickel electroplating bath according to claim 4, in Which the concentration of the sulfo-oxygen compound is in the range from 1 to 20 grams per liter.

6. An aqueous acidic nickel electroplating bath in Which there is dissolved from about 0.1 to about 10 grams per liter of a hetero-cyclic organic compound of the group consisting of 2-(4-pyridyl) ethyl sulfonic acid and the alkali metal, magnesium, ammonium, and nickel salts thereof, and from about A to about 20 grams per liter of osulfobenzoic imide.

References Cited in the file of this patent UNITED STATES PATENTS 2,513,280 Brown July 4, 1950 2,550,449 Brown Apr. 24, 1951 2,644,788 Shenk July 7, 1953 2,647,866 Brown Aug. 4, 1953

Claims

1. THE PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT IN WHICH THERE IS DISSOLVED FROM ABOUT 0.1 TO ABOUT 10 GRAMS PER LITER OF A HETEROCYCLIC ORGANIC COMPOUND OF THE GROUP CONSISTING OF 2-(4-PYRIDYL) ETHYL SULFONIC ACID AND THE ALKALI METAL, MAGNESIUM, AMMONIUM, AND NICKEL SALTS THEREOF, AND FROM ABOUT 1/4 TO ABOUT 80 GRAMS PER LITER OF A WATERSOLUBLE SULFO-OXYGEN COMPOUND OF THE GROUP CONSISTING OF UNSATURATED ALIPHATIC SULFONIC ACIDS, MONONUCLEAR AND BINUCLEAR AROMATIC SULFONIC ACIDS, MONONUCLEAR AROMATIC SULFINIC ACIDS, THE ALKALI METAL, MAGNESIUM, AMMONIUM, AND NICKEL SALTS OF SAID ACIDS, AND MONONUCLEAR AROMATIC SULFONAMIDES AND SULFONIMIDES.