CA1069850A

CA1069850A - Low temperature bright nickel and bright nickel alloy plating

Info

Publication number: CA1069850A
Application number: CA265,465A
Authority: CA
Inventors: Sidney C. Beach; Jack D. Fellman
Original assignee: Mcgean Chemical Co
Current assignee: Mcgean Chemical Co
Priority date: 1975-12-04
Filing date: 1976-11-12
Publication date: 1980-01-15
Also published as: AU513891B2; BR7608097A; JPS5268827A; ES453817A1; IT1076845B; FR2333875A1; FR2333875B1; DE2654040A1; GB1550876A; AU2025776A

Abstract

LOW TEMPERATURE BRIGHT NICKEL
AND BRIGHT NICKEL ALLOY PLATING

Abstract of the Disclosure A method of obtaining satisfactory bright electrodepo-sits of nickel, nickel-cobalt and nickel-iron while minimizing the amount of energy necessary to heat the plating bath to a suitable plating temperature is provided which comprises controlling the basic plating bath formulation, including addi-tion agents, and electrodepositing the desired metal at a temperature ranging from about 85°F to 115°F.

Description

'' '~'' ~c~c~ u~_~___the Lnver~tion ln the art of nickeL an~ ni.ckel alloy pl~tin~, a con-siderable amount of energy is expended for hea~ing solu~ions, as - most such plating processes operate wi~h op~iTnum bath ~emperatures ranging from 140F to 165F. ~lost of the heating is done by steam which requires fossil fuels, such as gas or oil.
In view of the potential shorta~e of fuels, this inyen-tion has been directed toward the conservation of energy primarily in the area of platlng bright deposits of nickel, nickel-cobalt and nickel iron.
In ~he past, operating bright nickel formulations at low tempera~ures has created such problems as'burned or nodular ' deposits in the high current densi~y regions and the inability to build good deposit brightness and achieve leveling. In fact, recent experiments have shown that the basic c'hemical formulations normally employed in nickel plating, such as the Watts solution containing approximately 300 grams/liter of nickel sulfate, 60 grams/liter of nickel chloride, and 6.ounces/gallon of boric ~ ' ~ ' ' , , . . . . ..
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.f ~ , ~o~ o acicl, where the pll ranges rom ~bout 2.8 to about 4 5, wil~ not give satisfactory bright deposits a~ temperature6 below about 120F, primarily because of severe burned and nodular deposi~s that have a tendency to ~orm in the high curr~nt density regions.
It is to be noted that the prior art is replete with literature concerning various methods and techniques from the electrodeposition of nickel and nickel alloys. However,.the literature does not provide any teaching which could be said ~o even remotely suggest the instant invention as it is hereinaEter described and claimed.
Summary of the Inven~ion .
It has been found that with certain modifications of the basic bath formulations entirely satisfactory deposits of bright nickel and certaln alloys of nickel can be obtained while operat-ing at plating bath temperatures ranging Erom about 85F to 115F
thus saving signiEicant amounts oE energy. Experiments have sho~m that it is possible ~or a nickel or nickel alloy plating operation to be started at temperatures as low as about 75F and that the heat generated by the wattage expended during the course of plat-20 ing is all that is required to m~intain the bath temperature at a level where satisEactory deposits are obtained. It is recog-nized that slightly more electrical energy is required when `~ operating at lower temperatures, due to the decrease in conduc-tivity in the solution, but this additional energy usage is minute compared to the savings that are realized by the reduction or elimination of the external heat requirements that are needed : to maintain pri.or art nickel plaLin~ solutlons a~ the optimum temperatures.
In connection with the practice oE the :instant invention, it has been unexpectedly discovered that by reclucing the total .. ~ .

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35~) nickel ion concentrat:i.on, as clescr:i.be(l h--reina~l-er in de~ail, of the ylating bath and by the incorpora~ion therein of uni~lUe combina~ions o~ organic addition agents (hereinaf~er discussed) satisfactory deposits can be obtainecl while minlrni~ing the amount of energy necessary to heat the plating bath to a fiuitable plating temperature. The combination of lo~ nickel lon and addition agents taught by the instant invention produces suf.~'icient polarization of these high current density areas and thereby' . alters the normal pattern of current distribution so that burned' or nodular deposits are avoided. Extensive testing indicates that the deposits of the invention a~e achieved without loss o either cathode or anode efficiency as eompared to a Watts formu-lation'bath.
Also, in the praetice of the present invention, it is .15 noted that the reduction in the required amounts of nickel 'chemi-cals further reduces the cost of the operation of a nickel platlng solution, as salt losses due to drag out and spillage are auto-- matically recluced which, in turn, reduces waste treatment and replacement costs proportionately.
20 ' ' In one aspect, the invention concerns a method of obtaining a bright nickel base deposi-t, i.e., a deposit of nickel, nickel-cobalt or nickel-iron on a substrate by controlling the bath charaeteristics in order to minimiæe the amount of energy necessary to heat the bath to a suitable pla-tin~ temperature.
More specifically the presen-t invention concerns a method of obtalning a bright nickel base electrodeposit on a substrate by passing electric current through an aqueous acidic plating bath containing ions of the metal to be electrodeposited while minimizing the amount oE energy necess~ry ~o heat the plating bath to a suita'ble platin~ temperatllre which methocl .

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comprises prov;ding an aqueous ac:idic plating ba~h having a pH
ranging from al~out 2.~ to about 5.0 (usuall~ stabili~ed by means of a buffering agent, such as boric acid) which conLains fro~ about 25 to about 60 ~/1 of nickel ions, an efEective amount o~ ' chloride ions to cause satisfac~ory anode corrosion during the formation of ~he electrodeposit, an efective amount o~ at least one bath soluble primary 'brightener of the first class containing a sulfo-oxygen group, and an effective amount of at least.one bath soluble secondary brightener (as described herein), and main-.
taining the platlng bath at a temperature rangln~, from about 85F to about 115F whlle passing sufficient.electric current through said bath to cause the desired metal ta be deposited on -the substrate.
' . In the foregolng practlce of the lnventlon, the plating 15 bath contains from about 25 to about 60 g/l of the metal lons to .
be plated.. Accordlngly, when lt is desired to obtain a nlckel-cobalt deposlt, an approprlate amount of the nickel lons are - replaced wlth cobalt ions with the cobalt ions being present ln an amount ranging from about a trace amount to lS g/l. Likewlse, .when lt is deslred to obtain a nickel-iron deposit, an appropr,iate amount of the nlckel ions are replaced with ferrous ions with the ferrous ions being present in an amount ranglng from a trace amount to about 15 g/l. Obviously, when ferrous lons are included 'in the bath an effective amount of chelating'agent must be used to prevent the ferrous ions from precipitating.
. In connection with the above description oE the practlce of the subject lnventlon lt should be noted that the term "nickel base" ls intended to include nic'kel, nickel-coba'lt al'loys and nlckel-lron alloys.
'~ ' 30 In addition, the present invent:ion relates to novel .

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platiny, batlls WtliCh are utill~ed i.n connec~ion with the various me~hods gene~ally discussed above.
Description of the Pre:~erred Embodiments of the -rnvention - '' .
As before noted, a~tempts to o~erate conventional Watts type bright plating 'baths at low, energy saving temperatures have ' 5 been unsuccessful due in the main to the ~orma~ion of nodular deposits and the inability to build good deposit brightness-and achieve levelin~. In an attempt to overcome these problems it has been unexpectedly discovered that bright, level dèposits of nickel and nickel alloys can be obtained while operating at low, energy saving temperatures if (1) the p~l of the bath is'maintained in the range oE from about 2.8 to about 5.0 (usually by means of a buffering agent such as boric acid), (2) the concentration of-the metal ion to be plated is in the range of from about 25 to about 60 g/l, (3) the bath temperature is regulated so as to 15-- range from about 85 to about 115F, (4) an effective amount of chloride ion is present to cause satisfactory corrosion of the anode during plating, (5) a primary brightener of the first class is utilized'to obtain a fine grain deposit, and (6) a secondary brightener (of the described type) is utilized to obtain a fully bright and ductile deposit.
~- ' By utilizing the forego'in~ technique, a deposit is obtained which has leveling and.brightne~s properties which are equivalent to those obtained from conventional high temperature bright nickel baths.
The primary addition agents or bri~,hteners of the first class employed in the practice oE this invent-ion include the aryl.
and a'lkyl sulfo-oxygen compounds, such clS sulfonic aclds and their metal salts, sulfoxides, sulEonamides, suL~onimides, and sulfones Prillcipa'lly, these compounds are used to obtain a fine ~' : ,, ~ '' ', .
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~rain deposit. Since such co~npourlds a~e well known ~o those skilled in ~he art they wil1 I~O~ be discussed herein in.~urther detail.
Speci~ic compounds which have been ~ound to be especially efective ~or this purpose are set ~orth in ~he following Table I.
The concentrations of these materials and combinations thereof will vary widely, but generally the total concentration thereof in the bath ranges from abou~ 0.1 to about 30.0 g/-L.
Table 1 Sodium Benzene Sulfonate Sodium Meta-benzene Disulfonate Benzene ~ulfonamide p-Toluene Sul-~onamide Sodium p-Toluene Sulfonate Naphthalene Sulfonate

2,7-Naphthalene Dlsulfonate 1,5-Naphthalene Disulfonate Sodium Naphthalene Trisulfonate o-Sulfobenzoic Imide (saccharin) .` 20 Sodium Vinyl Sulfonate Sodium Al~yl Sul~onate ~ Sodium 2-Butene-1,4-Diol-2-Sulfonic Acid : Sodium Butane-].,4-Diol-2,3-DisulEonate . Sodium Thiophene Sulfonate 2-5 Sodium Styrene Sulfonate Pyridine-.3-Sulfonic Acid Dibenzene Sul-fonamide Not all known secondary brightening agents can be ~ employed with the compounds of Table I to give a full bright ....... ... ... .30 deposit in the practice of the instant invention. For exam~le, such well-known materials as triphenylmethane dyes, derivatives of pyridine and the like generally give a deposit that is defi-- cient in the degree of brightness, leveling and ductility. That is, deposits so obtained do not exhibit physical characteristics which are necessary for a commercially acceptable deposit.
Secondary brighteners that give ~he desired degree of brightness, leveling and dwcti]ity when used in combination with primary addition agents in the practice oE the. present ;.nvention . , .

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are the lo~er molecular weigh~ ace~ylenic alcohols (rnore speci-fically propargyl and bu~ne diol) and ~heir epo~ide adducts, their sulfona~ed adcluc~s, and their alkyl ether sul~onic acid.
~erivatives. The epoxide adducts are col~lmon'Ly formed,by condens-, 5 ing the appropriate acetylenic alcohol with alkylene oxides, such - as ethyiene oxide, propylene oxide and epichlorohydrin. Addition' agents or bri~hteners containing both tlle acetylenic linkage and' the sulfonic acid group are commonly preparecl,b~ reacting the.
' appropriate acetylenic alcohol wi~h cer~ain alkane sul'tones ,(such as propane sultone), or by condensing the appropriate acetylenic.
alcohol with a halogen-containing epoxide (such as epichlorohydrin) followed by replacement of the halogen atom with a sulfonate-group.
' . The generic formula for the secondary brightener used `: in the practice of the present invention is as follows:
' 15 , , RlC--ccH2OR2 ~ wherein Rl is selected from the group consisting oE H, CH2OH, CH2OR2; R2 is'selected from the group consistin~, of H, (CH2CH2O)nH, (CH2CH(OH)CH2)nl~, (C~12)mS03M, (C~12CH(O~)CH2)nS03M, (CH2CH ? (CH2CH(OH)CH2)SO3M, and (CH2CH2O)n(CH2)m 3 , . 20 an integer from 1 to 10; m is an integer rom 1 to 4; and M is~' selected from the group consisting oE hydro~en, ammonium, alkali , metal, nickel and cobalt.
'Speciic examples of these materials are set forth ln the . following Table II:

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Table II ' ' (See next pa~e).

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To ~la~e, experimen~al da~l has indicated that in connec-t:ion Witil the practice of the subject in-vention i~ is preferred to employ the secondary brightener in total concentra~on ranging froM about O.OOL to about 3.0 g/l.
In the evaluation of the nickel and nickel alloys deposited in accordance with che teachings of the instant inven-' tion, the op~imum bath temperature ranges from about 85'~o 115F.
At such te~peratures, the preferred range for nickel'metal ions is ~; u~ from about 25 to about 60 g/l (with cobalt or iron ion being present as described herein). In addition, :Erom a'bout 5 g/l to CR ~ about 50 g/l of chloride ions should be present, preEerably ' '~
obtained from nickel chloride, in order to ensure satisfactory corrosion of the nickel metal anode and increase the conductivity oE the solution. Any balance of nickel ion being made up either 15 '~ . as nickel sulfate, nickel sulfamate, nickel fluoborate, or other ~ . suitable nickel-containing compounds The p~l of the plating solution can be varied over a . . .
range of from about 2.8 to about 5.0, but optimum leveling and brightness is obtained in the range of about 3.6 to about 4.8.' For best results, the bath of the present invention should also:`~
'include boric acid as a buffering agentj with the preferred amount being àbout 60 g/l. However, it should be noted that any amount of buffering agent ranging from about 35 g/l (grams per liter) to saturation results in satisfactory system perormance, provided the pH of the bath is maintained within the be:Eore specified limits. Wetting agents can also be used in order to guard against - the possibility of pitted cleposlts from hydrogen evolution at the cathode surface or :oreign organic contaminat:ion o:E the bath.
In all nicke:L plating, some form of agitation or solution move-ment is preferably employed and it has been Eouncl thclt the standard method o air agitat:ion of the soL-l~ion, or continuous movement of the cathode, is necessary.
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In order ~o evaluate the presen~ inven~ion, ~he nickel solutions were put in 1000 ml air-agitated'~lull Cells, employing electrolytic nickel as the anode material and 3 1/~" x 5", ~7P-3'0 brass or polished steel test panels as the cathode. In theSe cells, the 40 angle of the cathode gives a current density ranging from 1 to 200 ASF when the applied current to the panel is 5 amperes. Specific examples of some preferred formulations used in the prac~ice of the invention are se~ forth in the following examples.

'' NiS04 6~l2 '75 grams/liter (Ni apPr.ox. 16.5 g/l) NiC12 6H2O 112 grams/liter (Ni approx. 26.5 g/l) Boric Acid 52 grams/liter ' pH Range 3.8 to 4.2 -15 Temperature range100F. to 110F.
- Saccharin. 3.2 grams/liter Sodium Benzene Suifonate2.0 grams/liter Sodium Allyl'Sulfonate2 0 grams/liter Sodium 2-Ethyl Hexyl Sulfonate 0.1 grams/liter Optimum concentrations of the various compounds set forth in Table II.

The deposits from these solutions were fully bright at all current densities and had good'ductility and leveling properties.
It was found that the leveling and brightness qualities ; could be increased to some degree by employing certain combina-tions of the acetylenic compounds of Table II The best of such combin.ations were primarily those that ernployed the acetylenic sulf~onates with an acetylenic alcohol or epoxide adduct ~hereof.
Specific examples of plating baths ~imilar to those ' described in '~xample 'L which employecl at 'least two secondary brighteners are described below.

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liXAMPL,E II
When 0.0~ g/l o:E compound 7 from Table II (Bis-B-hydroxyethyl ether-2-butyn-1,4-diol) was used wi~h 0.05 g/l of compound 10 of Table II (1~4-Dl(~ -hydroxy-A-sulfonic propo~y)-2-5' butyne), a deposit was obtained which was full-bright, leveled and ductile from 0.5 to 200 ASF (amps per square :~oot) and with no burning on the HCD (high current denslty) edge. 'The leveling in the LCD (low current density) region (0.5 to 40 AS~) was better than when the compounds were used by themselves, as in Example I.
EXAMPLE III
' ' When 0.02 g/l of compound 2 from Table II (hydroxy-ethyl, propynl ether) was used with 0.025 g/l of compound 9 cf Table II
(l-y-Sulfopropoxy-2-butyn-~-ol), a deposit was obtained which was ' full-bright, leveled and ductile from 0.5 to 200 ASE and with no burning on the HCD edge. The leveling in the LCD ~egion (0.5 to - 40 ASF) was better than when ~the compounds were used'by themselves, as in Example I. The results were comparable to those of ' Example II.
' EXAMPLE IV
. When 0.01 ~/1 of compound 1 from Table Il (Prop'argyl'~
alcohol) was used with 0.025 g/l of compound 9 o Table II
ulfopropoxy-2-butyn-4-ol), a deposit was obtained which was full-bright and comparable to Examples II and III in all respects.
EXAMPLE V
When 0.05 g/l of compound 8 from Table II (Bis-~
-~ hydroxpropyl ether-2-butyn-1,4-diol) was used with 0.025 g/l of compound 9 o~ Table II (l-Y-SulEopropoxy-%-~utyn-~-ol), a deposit was obtained which was full-bright and equivcilent to the previous examples.

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In colmec~ion wi~h the practice of the invent:ion, lt has been discovered that cobal~ or iron (toge~her ~ith a sui~able chelating agent) can be subs~ituted for up to about 25% of the nickel lon. Such alloy deposi~s are bright and duc~ile and commercially acceptable.
The substitution of cobalt ion for a portion or the nickel metal ion was shown to be possible, and the following example describes a method for producing an alloy deposit contain-ing approximately 40% cobalt and 60% nickel which is ful.ly bright with good leveling and ductility properties.
EXAMPLE VI
4 2 33.0 grams/liter CoS04 ~H2O 32.0 grams/liter NiC12 6H2o 75.0 grams/liter 15 . Boric Acid . 45.0 grams/liter - pH range 3.8 to 4 2 ~~Temperature range . . 100 to I10F.
Saccharin 3 2 grams/liter 2,7-Naphthalene Disulfonate .4.0 grams/liter 20. So~ium Allyl Sulfonate 2.0 grams/liter Bis-Hydroxyethylether-2-butyne-1,4.-diol: 0.04 grams/liter ` - 1,4-di(~ -hydroxy-~ -sulfonic ~- propoxy)-2-butyne: 0.06 grams/liter It has also been found that iron, as ferrous sulfate or : ferrous chloride, may be substituted for a portion of the nlckel ion to give a nickel-iron alloy deposit that contains 20 - 30%
iron, and 70 - 80% nickel, depending upon the ratio of nickel ion to iron ion in the solution. I:lowever, :in addition to the pre-` viously described additives, it is nece~sary that a suitable `- ` chelating agent be employed in order to keep the iron in a , _ 1'1 _ ,, 10~;~8SV
solubilizecl for~ plcal chela~:i.n~ ~Ig,erl~s i.nc'lutle such rnaterials as ~he alkall (~r nickel metal salts of cit'ric, ascorbic or gluconic aci~s.
The ~ol'Lowing example gave a brlght, duc~ile and level' alloy deposit that analyzed as 13.4% lron, with the balance nickel.
EXAMPLE VII
4 2 llZ grams/liter 6ll2o 60 grams/liter .. FeS04 7H20 20 grams/llter: ' Sodium Gluconate 22 grams/liter Boric Acid 45 grams/liter -~
p~ range 3.5 to 3.8 -Temperature 100F.
Saccharin 3.0 grams/li.-ter ' 15 Monobenzene Sulfonate 2.5 grams/liter ._ Sodium Allyl Sulfonate 2.0 gramsjliter Bis I-lydroxyethylether-2- .
' ' butyne-1,4-diol 0.04 grams/liter ' '1,4-di(~ -hydraxy- ~-sulfonic - propoxy)-2-butyne 0.06 grams/liter Whi]e there have been described herein what are, at present, considered to be the preferred embodiments of the inven-.. tion, 'it will be obvious to those skilled in the art that various changes and modi~ications may be made therein without departing from the spirit and scope of the invention as hereinafter claimed.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of obtaining a bright nickel base electro-deposit on a substrate by passing electric current through an aqueous acidic plating bath containing ions of the metal to be electrodeposited while minimizing the amount of energy necessary to heat the plating bath to a suitable plating temperature which method comprises:
providing an aqueous acidic plating bath having a pH
ranging from about 2.8 to about 5.0 which contains from about 25 to about 60 g/l of nickel ions, chloride ions in an amount sufficient to effect satisfactory anode corrosion during the formation of said electrodeposit, an effective amount of at least one bath soluble primary brightener of the first class containing a sulfo-oxygen group, and an effective amount of at least one bath soluble secondary brightener having the formula:
R1C?CCH2OR2 wherein R1 is selected from the group consisting of H, CH2OH, CH2OR2; R2 is selected from the group consisting of H, (CH2CH2O)nH, (CH2CH(OH)CH2)nH,(CH2)mSO3M, (CH2CH(OH)CH2)nSO3M, (CH2CH2O)n(CH2CH(OH)CH2)SO3M, and (CH2CH2O)n(CH2)mSO3M, where n s an integer from 1 to 10; m is an integer from 1 to 4, and M is selected from the group consisting of hydrogen, ammonium, alkali metal, nickel and cobalt;
maintaining said plating bath at a temperature ranging from about 85°F to about 115°F. while passing sufficient electric current through said bath to cause the desired metal to be deposited on said substrate.

2. The method of claim 1 including the step of substitut-ing at least a part of said nickel ions with cobalt ions, said cobalt ions being present in an amount ranging from a trace amount to about 15 grams per liter.

3. The method of claim 1 inciuding the steps of (a) substituting at ieast part of said nickel ions with ferrous ions with said ferrous ions being present in an amount ranging from a trace amount to 15 grams per liter and (b) provlding an effective amount of chelating agent for said ferrous ions.

4. The method of claim 1 wherein said brightbner o the first class is selected from the group consisting of sulfonic acids, metallic salts of sulfonic acids, sulfoxides, sulfonamides, sulfonimides, and sulfones.

5. The method of claim 1 wherein said brlghtener of the first class is present in an amount ranging from 0.1 to about 30.0 grams per liter.

6. The method of claim 1 wherein said secondary brightener is present in an amount ranging from about 0.001 to about 3.0 grams per liter.

7. The method of claim 1 wherein the pH of said bath is malntained in the range of from about 3.6 to about 4.8.

8. The method of claim 1 wherein said chloride ion is present in an amount ranging from about 5 to about 50 grams per liter.

9. The method of claim 1 wherein a buffering agent is present in said bath.

10. The method o claim 9 wherein said buffering agent is boric acid.

11. The method of claim 10 wherein boric acid is present in an amount ranging from about 35 grams per liter to about an amount sufficient to saturate said bath.

12. The method of claim 10 wherein the concentration of boric acid in said bath is about 60 grams per liter

13. The method of claim 1 wherein at least two secondary brighteners are present.

14. The method of claim 3 wherein said chelating agent is selected from the group consisting of alkali or nickel salts of citric acid, ascorbic acid, gluconic acid and mixtures thereof.

15. An aqueous acidic plating bath for forming nickel base electrodeposits and having a pH ranging from about 2.8 to about 5.0 which contains from about 25 to about 60 g/l of nickel ions, from about 5 to about 50 g/l of chloride ions, an effective amount of at least one bath soluble primary brightener of the first class containing a sulfo-oxygen group, and an effective amount of at least one bath soluble secondary brightener having the formula, R1C?CCH2OR2 wherein R1 is selected from the group consisting of H, CH2OH, CH2OR2; R2 is selected from the group consisting of H, (CH2CH2O)nH, (CH2CH(OH)CH2)nH, (CH2)mSO3M, (CH2CH(OH)CH2)nSO3M, (CH2CH2O)n(CH2CH(OH)CH2)SO3M, and (CH2CH2O)n(CH2)mSO3M, where n is an integer from 1 to 10; m is an intcger from 1 to 4, and M is selected from the group consisting of hydrogen, ammonium, alkali metal, nickel and cobalt.

16. The plating bath of claim 15 wherein at least part of said nickel ions have been replaced with cobalt ion, with said cobalt ion being present in an amount ranging from about a trace amount to 15 grams per liter.

17. The plating bath of claim 15 wherein (a) at least part of said nickel ions have been replaced with ferrous ions with said ferrous ions being present in an amount ranging from a trace amount to 15 grams per liter and (b) an effective amount of chelating agent for said ferrous ions is present.

18. The plating bath of claim 15 wherein boric acid is present as a buffering agent.

19. The plating bath of claim 18 wherein said boric acid is present in an amount ranging from about 35 grams/per liter to an amount necessary to saturate said bath.