US3862019A

US3862019A - Composition of electroplating bath for the electrodeposition of bright nickel

Info

Publication number: US3862019A
Application number: US464558A
Authority: US
Inventors: William E Rosenberg; William J Saas
Original assignee: Hull R O and Co Inc
Current assignee: Hull R O and Co Inc
Priority date: 1974-04-26
Filing date: 1974-04-26
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: AU7394874A; JPS50139035A; JPS5646559B2

Abstract

An aqueous, acid electroplating bath which contains as brightening agents the synergistic combination of N-(3sulfopropyl) pyridinium inner salt and an acetylenic alcoholethylene oxide adduct.

Description

United States Patent Rosenberg et al.

[ 1 Jan. 21, 1975 COMPOSITION OF ELECTROPLATING BATH FOR THE ELECTRODEPOSITION OF BRIGHT NICKEL Inventors: William E. Rosenberg, Strongsville;

William J. Saas, Fairview Park, both of Ohio Assignee: R. 0. Hull & Company, Inc.,

Cleveland, Ohio Filed: Apr. 26, 1974 Appl. No.: 464,558

U.S. Cl. 204/49 Int. Cl. C23b 5/08, C23b 5/46 Field of Search 204/49, 43 T, 43 N, 43 P,

Primary Examiner-G. L. Kaplan Attorney, Agent, or FirmO1dham & Oldham C0.

[57] ABSTRACT An aqueous, acid electroplating bath which contains as brightening agents the synergistic combination of N-(3-su1fopropy1) pyridinium inner salt and an acetylenic alcohol-ethylene oxide adduct.

8 Claims, No Drawings BACKGROUND OF THE INVENTION This invention relates to an aqueous acid electroplating bath for producing extremely bright, level electrodeposits of nickel. The use of N-(3-sulfopropyl) pyridinium inner salts as a bath additive is disclosed in US. Pat. No. 2,876,l77. It is used alone or in combination with diarylsulfimides. The deposits obtained using a bath containing this combination or the pyridinium inner salt alone are level but only semibright. However, the deposit is somewhat brittle and if more brightener is added to achieve a higher degree of brightness and leveling, the brittleness increases and there is a definite darkening of the plate in low current density areas. Such brittleness and plate discoloration is totally unacceptable for suitable plating.

The use of acetylenic alcohol-ethylene oxide adducts is also known in the electroplating industry and is disclosed in U.S. Pat. No. 3,140,988. They are used alone and in combination with allyl sulfonic acid, and aryl sulfonic amides and acids. US. Pat. No. 3,366,557 discloses similar combinations and U.S. Pat. No. 3,11 1,466 discloses the combination of coumarin and ethylene oxide adducts of acetylenic alcohols.

However, in all three of these disclosures utilizing the acetylenic alcohol adducts at best only semibright and moderately level electrodeposits are obtained. Moreover. it has been found that by excessively increasing the concentration of the brighteners in the electroplating baths, electrodeposits exhibiting extremely high brightness and leveling cannot be obtained.

These brightening systems, therefore are limited in at least the following aspects:

1. The system using the pyridinium inner salt is limited in that increasing the concentration to achieve extremely high luster and leveling produces unacceptable, brittle and dark electrodeposits; and

2. The systems using the acetylenic alcohol adducts cannot produce electrodeposits of extremely high brightness and leveling even at very high concentrations in the electroplating bath.

SUMMARY OF THE INVENTION Accordingly, it is an object of the invention to provide brightening agents which produce extremely bright, level and ductile electrodeposits of nickel.

It is another object of the present invention to produce an extremely bright electrodeposit of nickel, as above, through the synergistic combination of two groups of compounds, even in low current density areas.

These and other objects of the present invention, together with the advantages thereof over existing prior art compounds and methods which will become apparent from the following specification are accomplished by the compounds and methods herein described and claimed.

In general, a plating bath for the electrodeposition of nickel. comprises, an aqueous acidic solution of at least one nickel salt and. as brightening agents, from 0.02 to about 0.5 grams/liter of N-(3-sulfopropyl) pyridinium inner salt and from 0.005 to about 0.2'grams/liter of an acetylenic alcohol-ethylene oxide adduct having the general formula where R, is hydrogen, hydroxymethyl, and 2-hydroxyethoxymethyl and R is 2-hydroxyethoxymethyl.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the concepts of the present invention, it has been found that the synergistic combination of an N-(3-sulfopropyl) pyridinium inner salt and an acetylenic alcohol-ethylene oxide adduct produces both extremely bright and level electrodeposits of nickel at very low concentrations in an aqueous acidic nickel plating bath. Additionally, the electrodeposit is extremely ductile. The effect is truly synergistic in that the results obtained with this combination far exceed those of using the two types of compounds separately and at brightener concentrations of only a small fraction of previously required amounts.

The pyridinium inner salt of the present invention has the following formula:

All-12011: AII:

This specific salt is generally not commercially available but may be readily synthesized by the condensation of pyridine and propane sultone.

The aceylenic alcohol-ethylene oxide adducts of the present invention are available in commerce and have the following general formula:

where R, is hydrogen, hydroxymethyl, and Z-hydroxyethoxymethyl, and R is Z-hydroxyethoxymethyl. The chemical structures of these compounds are set forth in Table I.

TABLE I 1. HOCH CH OCH C CCH OH 2. HOCH- CH OCH C CH 3. HOCH CH OCH C"CCH OCH CH OH The brighteners of this invention can readily be used in conjunction with other known conventional brighteners in generally small or conventional amounts such as allyl sulfonic acid, aromatic sulfonic acids, and aromatic sulfonamides and sulfonimides; specific examples include saccharin, dibenzenesulfonimide and naphthalene trisulfonic acid.

The pyridinium inner salt and acetylenic alcoholethylene oxide adducts of this invention are generally added as aqueous solutions, but they can be added in concentrated form or dissolved in another suitable solvent such as methanol or ethanol. A general range extends from 0.02 to about 0.5 grams/liter of plating bath for the pyridinium inner salt and from 0.005 to about 0.20 grams/liter of the plating bath for the acetylenic alcohol-ethylene oxide adduct. More specifically, the preferred concentrations are about 0.05 to about 0.3 gms with roughly 0.18 gms being an optimum amount of the' pyridinium inner salt and about 0.01 to about 0.10 gms with roughly 0.03 gms being an optimum amount of the acetylenic alcohol-ethylene oxide adduct per liter of bath.

Continued pH 4.2 Temperature I4()F.

Table I shows the tests that were run in this bath under the above mentioned conditions to demonstrate the unique synergism between the N-(3-sulfopropyl) pyridinium inner salt and the ethylene oxide adducts of amount of time will, of course, vary depending upon m the acetylenic alcohols.

TABLE I] Test Brighteners Used Concentration Results in g/l 1 HC 5 cCH OCH CH OH 0.03 Very dull deposit 2 HC ii CCH OCH CH OH 0.15 Very dull deposit 3 IAI%CHH CH OCH,C I CCH OCH C- 0.03 Very dull deposit 2 4 go ci-ucl-uocu c i CCH,OCH,C- 0.15 Very dull deposit H 2 5 N-(3-sulfopropyl) pyridinium 0.06 Very dull deposit inner salt 6 N-(3-sulfopropyl) pyridinium 0.l8 Semibri ht and inner salt cloudy eposit 7 N-(3-sulfopropyl) pyridinium 0.48 Sembri ht but inner salt brittle eposit and dark in low current density 8 HC CCH,OCH CH OH 0.03 Semibright, very Soluble saccharin 3 little leveling 9 HOCH,CH OCH C CC- 0.03 Semibright, very H OCH CH OH Soluble saccharin 3 little leveling l0 HOCH,CH,OCH C CH OH 0.03 Semibright, very Soluble saccharin 3 little leveling l l HC I CCH OCH CH,OH 0.03 Extremely bright,

N-(3-sulfopropyl) pyridinium 0. 18 excellent leveling, inner salt and bright in low and bright in low current density 12 II II%CHH CH OCH C Ii CCH OCH C- 0.03 Extremely bright,

2 N-(3-sulfopropyl) pyridinium 0.l8 excellent leveling, inner salt and bright in low current density [3 HOCH,CH 0CH C n CCH OH 0.03 Extremely bright,

N( 3-sulfopropyl) pyridinium 0.l8 excellent leveling,

and bright in low current density 14 :(6CH CH,OCH C I CCH OCH c- 0.03 Extremely bright,

H z N-(3-sulfopropyl) pyridinium 0. 18 excellent leveling inner salt and bright in low Soluble saccharin 3 current density Note: All test baths contained 0.3 g Sodium Lauryl Sulfate/liter to prevent gas streaking and pitting. Generally, any suitable surfactant may be used. A suitable surfactant is one that prevents gas streaking and pitting but does not interfere with brightness of the electrodeposit.

INGREDIENT CONCENTRATION Nickel Sulfate 36 ozJgal Nickel Chloride l0 ozJgal Boric Acid 6.5 o7./gal

As can be seen from the results of Table H, the ethylene oxide adducts of acetylenic alcohols and N-(3- sulfopropyl) pyridinium inner salt act synergistically when both are added to an aqueous acid nickel electroplating bath to produce extremely bright, level electrodeposits of nickel. When these compounds are added separately, even in large amounts, only semi-bright, cloudy, and in some cases brittle deposits result.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carrying out this invention in accordance with the Patent Statutes, the subject matter which is regarded as being our invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or substitutions for, parts of the above specifically described embodiment of the where R is hydrogen, hydroxymethyl. or Z-hydroxyethoxymethyl, and R is Z-hydroxyethoxymethyl.

2. A plating bath according to claim 1 including a suitable surfactant in an amount sufficient to prevent gas streaking and pitting.

3. A plating bath according to claim 2, including at least one compound selected from the group consisting of allyl sulfonic acids, aromatic sulfonic acids, aromatic sulfonamides and aromatic sulfonimides in an amount sufficient to further enhance the nickel deposit brightness.

4. A plating bath according to claim 2, wherein there is also present saccahrin in an amount sufficient to prevent gas streaking and pitting.

5. A plating bath according to claim 2, wherein there is also present dibenzenesulfonimide in an amount sufficient to prevent gas streaking and pitting.

6. A plating bath according to claim 2, wherein there is present naphthalene trisulfonic acid in an amount sufficient to prevent gas streaking and pitting.

7. A plating bath according to claim 1, wherein the amount of said N-( 3-sulfopropyl) pyridinium inner salt ranges from about 0.05 to about 0.3g/l and the amount of said acetylenic alcohol-ethylene oxide adduct ranges from about 0.01 to about 0.lg/l.

8. A plating bath according to claim I, wherein the amount of said N-(3-sulfopropyl) pyridinium inner salt is approximately 0.]8g/l and the amount of said acctylenic alcohol-ethylene oxide adduct is approximately 0.03g/l.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 019 Dated January 1975 Inventor) William E. Rosenberg and William J. Saas It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 9 delete "0.02" and, in its place, insert O.2.

Signed and Scaled this Tenth D a y Of September 1985 [SEAL] A nest:

DONALD J. QUIGG A nesting Officer Acting (Lommissioner of Patents and Trademarks Designate UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 362,019 DATED January. 21, 1975 INVENTOR(S) William E. Rosenberg and William J. Saas It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 8, after "N-(3-si1lfopropyl)" insert .pyridinium Signed and Scalcd this second Day of December1975 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN A nesting Offirtr (0mm issiuner ofPatnls and Tmdemarks

Claims

2. A plating bath according to claim 1 including a suitable surfactant in an amount sufficient to prevent gas streaking and pitting.
3. A plating bath according to claim 2, including at least one compound selected from the group consisting of allyl sulfonic acids, aromatic sulfonic acids, aromatic sulfonamides and aromatic sulfonimides in an amount sufficient to further enhance the nickel deposit brightness.
4. A plating bath according to claim 2, wherein there is also present saccahrin in an amount sufficient to prevent gas streaking and pitting.
5. A plating bath according to claim 2, wherein there is also present dibenzenesulfonimide in an amount sufficient to prevent gas streaking and pitting.
6. A plating bath according to claim 2, wherein there is present naphthalene trisulfonic acid in an amount sufficient to prevent gas streaking and pitting.
7. A plating bath according to claim 1, wherein the amount of said N-(3-sulfopropyl) pyridinium inner salt ranges from about 0.05 to about 0.3g/l and the amount of said acetylenic alcohol-ethylene oxide adduct ranges from about 0.01 to about 0.1g/l.
8. A plating bath according to claim 1, wherein the amount of said N-(3-sulfopropyl) pyridinium inner salt is approximately 0.18g/l and the amount of said acctylenic alcohol-ethylene oxide adduct is approximately 0.03g/l.