US2839459A

US2839459A - Electroplating

Info

Publication number: US2839459A
Application number: US622532A
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

United States PatentO Red Bank, N. 1., assignors to Hanson-Van Winkle-Munning Company, a corporation of New Jersey No Drawing. Application November 16, 1956 Serial No. 622,532

6 Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepositing nickel from an aqueous acidic nickel plating bath. The invention is based on our discovery that a-amino N-heterocyclic compounds, when incorporated in a nickel electroplating bath, particularly in conjunction with various sulfo-oxygen compounds, are capable of promoting the formation of excellent bright and ductile electrodeposits of nickel over a wide current density range.

The electrodeposition of nickel from a plating bath containing a sulfo-oxygen carrier brightener additive yields deposits of limited intensity. Moreover, such brightness as is produced using these agents is obtained only over a limited current density range. When, however, a small quantity of an oa-amino N-heterocyclic compound is incorporated in the plating bath together with a sulfooxygen compound, the brightness capacity of the bath is extended, and the electrodeposit is 'ductile and bright over a very wide current density range.

The common structural feature of these. u-amino-N- heterocyclic compounds is the presence of an amino group on an unsaturated carbon in a position alpha to the heterocyclic nitrogen atom, as represented by the following structural formula: I r

Only relatively small quantities of the a-amino N-heterocyclic compounds are required in the plating bath, especially when they are used in conjunction with sulfooxygen carrier brightener, forwe have found that the highly polarized spatial configuration of an ot-amino N- heterocyclic compound appears to exert a pronounced synergistic eifect on the brightening capacity of the sulfooxygen compound. In general, concentrations of the ocamino N-heterocyclic compound as loW as 0.005 gram per liter are effective, but in many cases at least 0.08 gram per liter should be employed to secure the full benefit of their presence in the bath. Increasing the concentration of these amino compounds may produce brittle and perhaps cloudy deposits, and hence there is no advantage generally in using more than 1 gram perliter, and in most baths substantially full benefit of their presence is achieved with 0.3 gram per liter or less.

Any a-amino N-heterocyclic compound which is capable of being dissolved by acid and does not undergo decomposition upon protonation may be selected for inclusion in the plating solution. We have obtained particularly satisfactory results by using a carbon-nitrogen heterocyclic compound having an aromatic six-membered cyclic nucleus containing from 1 to 3 nitrogen atoms and at least one amino group. attached to a carbon atom in a position alpha to the heterocyclic nitrogen. The basic ring structure for such a-amino N-heterocyclic compounds may be chosen from pyridines, pyridazines, pyrimidiues, pyrazines, and 1,3,54riazines.

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 2,839,459 Patented June 17, 1958 0.08 to about 0.3 gram per liter of a nitrogen-containing heterocyclic compound of the group consisting of:

(a) a-Aminopyridines having the structure (b) a-Aminopyridazines having the structure NH: R1

(d) a-Aminopyrazines having the structure N N H: and

(e) a-Amino-1,3,5-triazines having the structure I R LN/ NH:

in which Z is a substituent selected from the group con sisting of hydrogen and Z-pyridyl radicals,and R and R are substituents selected from the group consisting of hydrogen, amino, methyl, ethyl, and propyl radicals. The synergistic eitect of these compounds on the brightening capacity of various sulfo-oxygen compounds is especially pronounced when they are used in the nickel plating solution together with from about A to about 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides.

Preparation of the a-amino N-heterocyclic compounds may be effected by a variety of standard organic reactions. For example, the a-aminopyridines may be prepared by heating pyridine or an alky -substituted pyridine with sodamide, since the sodamido ion attacks the pyridine nucleus at the carbon atom alpha to the ring nitrogen. One general technique which is useful in preparing all of the u-amino N-heterocyclic compounds is based on initialy forming the a-carboxamide of the: N-heterocyclic compound. Upon treatment with sodium hypobromite, the carboxamide undergoes decarbonylation to form the corresponding OL'aInlnO N-heterocyclic compound.

Examples of the ooaminopyridines, ot-aminopyridazines,, a-aminopyrimidines, ot-aminopyrazines, and aamino-1,3,5-triazines, which may be used successfully in embodiments of this invention are listed in Table I. Although these oa-amino N-heterocyclic compounds may be used in concentrations as high as one gram per liter, or even more, there is no particular advantage to be gained from the higher concentrations, and they are preferably TABLE I Alpha-amino N-heterocyclic compounds Compounds R1 R2 R3 R4 Z (1) a-Aminopyridincs Ra- R1 R4- NH-Z Z-aminopyridine H H H H H 2-amino-3-methylpyridine .7 CH H H H H 2-ammo-4-n1cthy1pyridine H CH H H H 2-amin0-5-methylpyridine .7 H H3 CH H 1-]. 2-amin0-6-methylpyridine H H H CH H 2-amino-4-ethylpyridine H H Cal-l5 H H H 2-amin0-4-isopropylpyridine H C21I5 H H H 2-amino-4,fi-dimethylpyridinc.. H CH3 H OH; H H NH? H H H H H H NH; H H H H H Cal-LN amine .7 H CH H H CsHiN 2- (4-aminopyridyl) -2-pyridylamine H NH2 H H csHiN 2,4-diamino-6methylpyridine H NH; H CH3 H (2) a-Aminopyridazines 1 Rr w NHa I N R3 \N/ 3-aminopyridazine H H H 3-amino-G-methylpyridazine H H CH3 3-amino-6-ethylpyridazinc M H H C 11,; 3-amino-fi-isopropylpyridazine H H C3H1 3,6-diaminopyridazine H H NH (3) a-Aminopyrimidines 2-amjnopyrimidine H H H 2-ami110-4-methylpyrimidine H H CH 2-a min0-4,6-dimethylpyrimi- (11110 CH3 Ii CIL; 2-amino-3-ethylpyrimidine H H C2115 2,6-diaminopyrimidine NH H H 2,6 diamino 3 mcthylpyrimi dine NHQ CH H 2,6 diamino 4 methylpyrimi dine is NHZ H CH (4) a-Aminopyrazines N R R1 R3 N NH2 2-aminopyrazin H H H 2-amin0-5-mcthylpyrazine H CH H 2,6-diaminopyrazinc H 2,3-diaminopyrazinc NH H 2-amino-5,6-dimethylpyr 2-amino-3,5-dimethylpyrazine (5) a-Amino-1,3,5-triazines I L H RrLN N 2 2-amino-1,3,5-triazine H H 2,4-diamino1,3,5-triazinc H NH 2,4 diamino 6 methyl 1,3,5

triazine CH3 NH? v c 2-ami110-4,6-dimethyl-1,3,5-

triazine CH CH 2-a1nin0-4,6-diethyl-1,3,5-trifiZl-HQ C2115 C2111; a a a a The compounds listed in Table II are examples of sulfo-oxygen compounds which, when used in the plating bath in combination with the ii -amino N-heterocyclic 4 compounds, extend the current density range over which the formation of bright and ductile nickel deposits may be obtained. These sulfo-oxygen compounds may be used over a very wide range of concentrations (M1, to 80 grams per liter), but preferably are used in an amount in the range from about 1 to about grams per liter. TABLE II Organic sulfo-oxygcn compounds -(1) Unsaturated aliphatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof: Sodium vinyl sulfonate, H CCHSO Na Sodium allyl sulfonate, H CCHCH 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 monosulfonate, (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, B1'C H SO Na Sodium p toluene sulfinate, CH C H SO Na magnesium, and nickel salts are in all (4) Mononuclear aromatic sulfonamides and sulfonimides Benzene sulfonamide, C H SO NH p-Toluene sulfonamide, CH C H SO NH o-Sulfobenzoic imide, CtlH4C ON HS 0 2 Benzyl sulfonamide, C I-I CH SO NH Benzene sulfhydroxamic acid, C H SO NHOH N,N-dimethyl-p-toluene sulfonamide,

(zu c mso iucn, N,N-dicarboxyethyl benzene sulfonamide,

C H SO N C H COOH) 2 (5.) Binuclear aromatic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof:

Z-naphthalene monosulfonic acid, CmI'IqSOgli 1,5- or 2,7-naphthalene disulfonic acid, C H (SO H) Nickel 1,5- or 2,7-naphthalene disulfonate,

Sodium naphthalene trisulionate, C H (SO Na) Naphthalene trisulfonic acid, C H (SO H) Diphenyl p,p'-disulfonic acid, HSO C H -C H SO H 2-naphthol-3,6-disulfonic acid, HOC iI (SO H) Sodium 2-naphthol-3,6-disulfonate, HGC H (SO Na) 1-naphthylamine-3,6,8-trisulfonic acid,

(6) Heterocyclic sulfonic acids, and alkali metal, ammonium, magnesium, and nickel salts thereof: Thiophene sulfonic acid, 0 11 860 3 Sodium thiophene sulfonate, C fi S-SO h-ia 2 -(4-pyridyl)ethyl sulfonic acid, C H I-I-Q H SO I-I For the most part, only free sulfonic acids listed. in Table II. However, the alkali i am? uium,

i the full equivalent of the acids, and may be used in their place in carrying out the process of the invention.

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 effective in all other nickel electroplating baths, and consequently the invention is applicable to electrodeposition from any aqueous acidic plating solution of one or more nickel salts.

To illustrate the applicability of using the ot-amino N-heterocyclic compounds in different nickel electroplating baths under a variety of conditions, Table III 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 III Bath concentrations in grams per liter Bath A Bath B Bath Nickel sulfate Nickel chloride Nickel sulfamate Nickel tiuoborate"- Boric acid 37. 30 15 EXAMPLE I To the Watts bath (bath A) described in Table III were added 16 grams per liter of sodium naphthalenel,3,6-trisulf0nate. A test panel which received a nickel electroplate from this bath was semi-bright over a wide current density range, but exhibited slight haziness in the low and middle current density range. Upon the addition of various concentrations of representative a-amino N-heterocyclic compounds to this bath, exceptionally bright electroplates were formed in each case over a very wide current density range.

Table IV sets forth in detail the concentrations of specific ct-amino N-heterocyclic compounds added to a Watts bath (bath A) which also contained 16 grams per liter of sodium naphthalene-1,3,6-trisulfonate, and the character of the deposit produced from the bath.

TABLE IV Efiect of a-amino N-heterocyclic compounds on bright nickel plating Identical results were obtained when only 8 grams per liter of sodium naphthalene1,3,6-trisulfonate were used in the plating solution in combination with the various ct-amino N-heterocyclic compounds.

EXAMPLE II As a general rule, the effect of the ot-amino N-heterocyclic compounds on the brightening capacity of the bath is more pronounced at the low and medium current densities. The testpanel of a Hull cell received a nickel electrodeposit from Bath A which contained 15 grams per liter of benzene disulfonic acid. The plated panel was fairly bright except at and near the high current density end, when it was streaked and matted. By adding 0.2 gram per liter of 2-aminopyrimidine to the electroplating solution, the nickel deposit became very bright almost over the entire current density range of the panel. Increasing the concentration of 2-aminopyrimidine to 0.3 gram per liter did not increase the brightness nor extend the range further.

EXAMPLE III Brilliant nickel deposits are formed when the a-amino N-heterocyclic compounds are used in conjunction with aromatic sulfonamides or sulfonimides. Table V summarizes the results obtained when the electroplate was formed from a Standard Watts plating solution (bath A) containing 2 grams per liter of o-sulfobenzoic imide (saccharin) together with varying concentrations of representative ot-arniuo N-heterocyclic compounds.

TABLE V Concen- Compound tration Character (grams) of deposit liter) 2-am1no-3-methy1pyridine 0. (l3 Brilliant. 2,2-dipyridylamine 8: E1 g8; 0.1. Do. 2-amn1opyr1m1dme 0 Do EXAMPLE IV To a sulfamate plating bath (bath B) which had been properly purified were added 15 grams per liter of so dium naphthalene-l,3,6-trisulfonate, and nickel electrodeposited on a Hull test panel at a total current of two amperes per 250 ml. Hull cell. The deposit was semibright over a wide current density range with a strong haze at the middle and low current densities. Upon the addition of 0.08 to 0.26 gram per liter of 2-aminopyridine to this bath, a very bright deposit was obtained over the entire current density range of the test panel. Similarly, when 0.008 to 0.016 gram per liter of 2,2- dipyridylamine or 0.06 gram per liter of 2-arninopyrimidine was added to the bath in place of the 2-aminopyridine, an equally bright electrodeposit was obtained over substantially as wide a current density range.

Substitution of 2 grams per liter of o-sulfobenzoic imide (saccharin) in the sulfamate bath. in place of sodium naphthalene-1,3,6-trisulfonate yielded brilliant electrodeposits when used in conjunction with the aforementioned concentrations of 2-arninopyridine, 2,2-dipyridylamine, and Z-aminopyrimidine.

EXAMPLE V Using a previously purified nickel fiuoborate bath (bath C) which contained 2 grams per liter of o-sulfobenzoic imide, a fairly bright electroplate was deposited on the test panel of a Hull cell operated at 50 C. and a pH of about 3.5. When, however, 0.08 to 0.26 gram per liter of 2-aminopyridine was added to the bath, the brightness range was substantially increased and a brilliant deposit formed. Similar results were obtained when 0.008 to 0.016 gram per liter of 2,2-dipyridylamine and 0.06 gram per liter of Z-aminopyrimidine were separately added to the bath in place of 2-aminopyridine.

We claim:

1. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aque ous acidic nickel electroplating solution in which there is dissolved from about 0.005 to about 1 gram per liter of an aromatic heterocyclic carbon-nitrogen compound having a six-membered cyclic nucleus containing from 1 to 3 nitrogen atoms and at least one amino group attached to a carbon atom in a position alpha to the heterocyclic nitrogen, and from about A1 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclcar aromatic sulfonamides and sulfonimides.

2. 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 A 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 0.08 to about 0.3 gram per liter of a nitrogen-containing heterocyclic compound of the group consisting of:

(a) a-Aminopyridines having the structure ([2) a-Aminopyridazines having the structure t at (c) wAminopyrimidines having the structure N -Rr (d) tt-Aminopyrazines having the structure lit-H R1 N NHZ and,

(e) otAmino-l,3,5-triazines having the structure wherein Z is a substituent selected from the group consisting of hydrogen and Z-pyridyl radicals, and R and R are substituents selected from the group consisting of hydrogen, amino, methyl, ethyl, and propyl radicals.

3, An aqueous acidic electroplating solution of at least one nickel salt in which there is dissolved from about 0.005 to about 1 gram per liter of an aromatic heterocyclic carbon-nitrogen compound having a six-membered cyclic nucleus containing from 1 to 3 nitrogen atoms and at least one amino group attached to a carbon atom in a position alpha to the heterocyclic nitrogen, and'from about A 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides.

4. An aqueous acidic electroplating solution of at least one nickel salt in which there is dissolved from about Mi to about grams per liter of a water-soluble sulfooxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic salfonamides and sulfonimides, and from about 0.08 to about 0.3 gram per liter of a nitrogen-containing heterocyclic compound of the group consisting of:

(a) ot-Aminopyridines having the structure N Nn-z (b) a-Aminopyridazines having the structure (c) a-Aminopyrimidines having the structures (d) ot-Aminopyrazines having the structure (e) a-Amino-l,3,5-triazines having the structure wherein Z is a substituent selected from the group consisting of hydrogen and Z-pyridyl radicals, and R and R are substituents selected from the group consisting of hydrogen, amino, methyl, ethyl, and propyl radicals.

5. 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 A1 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 0.08 to about 0.3 gram per liter of an a-aminopyridine having the structure wherein Z is a substituent selected from the group consisting of hydrogen and Z-pyridyl radicals, and R and R are substituents selected from the group consisting of hydrogen, amino, methyl, ethyl, and propyl radicals.

6. The process for producing bright nickel deposits which comprises clectrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about A to 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, heterocyclic sulfonic acids, mononuclear sulfinic acids, the alkali metal, ammonium, magnesium, and nickel salts of said acids, and mononuclear aromatic sulfonamides and sulfonimides, and from about 0.08 to about 0.3 gram per liter of an waminopyrimidine having the structure References Cited in the file of this patent UNITED STATES PATENTS 2,644,788 Shenk July 7, 1953 2,644,789 Shenk July 7, 1953 2,647,866 Brown Aug. 4, 1953 2,658,867 Little -2 Nov. 10, 1953

Claims

1. THE PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSIT WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC NICKEL ELECTROPLATING SOLUTION IN WHICH THERE IS DISSOLVED FROM ABOUT 0.005 TO ABOUT 1 GRAM PER LITER OF AN AROMATIC HETEROCYCLIC CARBON-NITROGEN COMPOUND HAVING A SIX-MEMBERED CYCLIC NUCLEUS CONTAINING FROM 1 TO 3 NITROGEN ATOMS AND AT LEAST ONE AMINO GROUP ATTACHED TO A CARBON ATOM IN A POSITION ALPHA TO THE HETEROCYCLIC NITROGEN, AND FROM ABOUT 1/4 TO ABOUT 80 GRAMS PER LITER OF WATER-SOLUBLE SULFO-OXYGEN COMPOUND OF THE GROUP CONSISTING OF UNSATURATED ALIPHATIC SULFONIC ACIDS, MONONUCLEAR AND BINUCLEAR AROMATIC SULFONIC ACIDS, HETEROCYCLIC SULFONIC ACIDS, MONONUCLEAR SULFINIC ACIDS, THE ALKALI METAL, AMMONIUM, MAGNESIUM, AND NICKEL SALTS OF SAID ACIDS, AND MONONUCLEAR AROMATIC SULFONAMIDES AND SULFONIMIDES.