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Publication numberUS2916401 A
Publication typeGrant
Publication dateDec 8, 1959
Filing dateFeb 10, 1958
Priority dateFeb 10, 1958
Publication numberUS 2916401 A, US 2916401A, US-A-2916401, US2916401 A, US2916401A
InventorsPuls Lawrence V, Vincent William R
Original AssigneeGen Motors Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Chemical reduction nickel plating bath
US 2916401 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

nited States Patent CHEMICAL REDUCTION NICKEL PLATING BATH Lawrence V. Puls, Ferndale, and William R. Vincent,

Birmingham, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware No Drawing. Application February '10, 1958 Serial No. 714,077

13 Claims. (Cl. 117'130) This invention relates to an improved bath and process for nickel plating by chemical reduction.

It is well known that various metals may be nickel plated by chemical reduction in an aqueous bath containing nickel ion and hypophosphite ion, the plating reaction being:

This reaction whereby the plating occurs is catalytic and autocatalytic, its initiation usually being accomplished by way of the catalytic effect of the article being plated and its continuance being catalyzed by the nickel which is deposited. Various metals may be plated by the process, for example, copper, gold, aluminum, iron, nickel, silver, cobalt, palladium, platinum. Magnesium and thorium also display the catalytic effect and theoretically, therefore, may be plated by the process; however, the plating of these metals has presented a serious problem in that when they are immersed in baths such as have heretofore been used, they are chemically attacked by the solution with the result that a satisfactory plate is not obtained.

It is an object of the present invention to provide an improved electroless nickel plating bath and process which is particularly useful for nickel plating magnesium and also thorium. Another object of the invention is the provision of an electroless nickel plating bath and process which provides an improved nickel deposition and which has improved stability even in the presence of magnesium and thorium. While the bath and process have particular utility and advantages in the plating of magnesium and thorium, other metals such as those mentioned above may also be plated, the improved stability and the high plating rate of the bath and process being highly advantageous irrespective of the precise metal being plated. Other objects and advantages of the invention will appear more fully from the following description of various embodiments thereof.

In accordance with the invention the aqueous nickel plating bath is formulated to contain the following ingredients in the concentration indicated:

Nickel ion From .005 to .20 mole per liter. Hypophosphite ion From .01 to .40 mole per liter. Fluoride ion From .20 to 1.0 mole per liter.

Alkyl or alkanol amine Sufficient to provide an N to Ni++ ratio of from 1:1 to :1.

Carboxylie acid or salt thereof as a Suifieient; to produce a carboxyl buffer. group-toypophosphite ion ratio from 1:1 to 10:1. Initial pH 7 to 11.

amples, the carboxylic acid used as the buffer may be a polycarboxylic acid or an hydroxy carboxylic acid. Sincea polycarboxylic acid furnishes more carboxyl groups per mole than, does a monocarboxylic acid, their use is generally desirable. We prefer to use citric acid as the buffer.

The amine must be sutficiently soluble in the bath to provide the desired concentration, and must also have a sufficiently high boiling point so that it is not lost due to evaporation at the desired bath temperature which should be in the range of F. to 210 F., preferably above F. Amines which are satisfactory are any of the primary, secondary or tertiary ethyl amines or propyl amines, ethylene or propylene 'diamine, ethanol amine, di or tri ethanol amine, methanol amine, di ortri methanol amine, propanol amine, or di or tri propanol amine.

The initial pH of the bath, which is on the alkaline side, may be adjusted-by addition of the amine ingredient or by the addition of sodium or potassium hydroxide. For optimum results, however, it is preferred that the N to N ratio be on the order of 5:1 and thus it is desirable to add just suflicient amine to provide this preferred ratio and then adjust the initial pH by the addition of potassium hydroxide or sodium hydroxide.

The following specific examples will serve to illustrate, Example I being the preferred bath by way of its precise ingredients and also by way of the amounts thereof which are used:

Example I Nickel sulfate -grams per liter.- 5.5 Sodium hypophosphite --do-- 8.3 Citric acid (in 10 Triethanolamine N(C H OH) -ml. per liter... 20 Ammonium bifluoride (NH F-HF) grams per liter 10 pH (adjusted by addition of NaOH) 8.0 Temperature F-. 205

Example II Nickel sulfate "grams per liter 5 Sodium hypophosphite do---- 8. Acetic acid do- 10 Triethanolamine --ml. per liter Approx. 60 Ammonium bifluoride -grams per liter.- 10 pH (adjusted by the amine added) 8.0 Temperature F..- 190 Example III Nickel sulfate grams per liter..- 5.5 Sodium hypophosphite ..do..... 83 Citric acid dn 9 Potassium fluoride do 11.8 Ethanolamine NH (C H OH) -ml. per liter-- pH (adjusted by addition of KOH) 8-0 Temperature F -190 Example IV Nickel sulfate grams per liter 11 Sodium hypophosphite do 16.6 Citric acid dn 17 Potassium fluoride do 21.7 Triethanolamine mls. per liter..- 40 pH (adjusted with KOH) 8.1 Temperature F 185-190 Example V Nickel sulfate "grams per liter-- 5 Sodium hypophosphite do 8.3 Citric acid do- 8 Ammonium bifluoride do.. 8 Triethylamine N(C H --mls. per liter-- Approx. 80 pH (adjusted by the amine added) 10.85 Temperature F... 210

To practice the process of the invention, the magnesi- ;ll ,1- thn m. or other metalarticle to be plated :is first t roughly .cleaned by conventional degreasing and chemical. cleaning procedures and .is then immersed. into the bath until the desired :plating. thickness is obtained.

The. precise plating. rate attained is dependentupon the concentrations .of -thefbath :ingredients and also upon hathtemperature. :In general,.the' higher the nickel in concentration .and the higher the temperature, thefaster the:plating ratmkhowever =with increased nickel concentration =and- ;with increased: temperature the greater is the possibility-of bath instability. The preferred bath as set forth in ExampleI-provides an initial plating rate ofabout .0015 inch per hour .which is excellent; at the same time, this bathis verystableand can therefore be operated on a production basis-without the hazardof precipitation occurring.

After the bath hasbeen operated -for-a time it may, if desired, be'replenished 'bythe addition-of nickel ion, -hypophosphite ion and potassium or sodium hydroxide. For example a bath as specified in Example V above was operated untilthere was substantial depletion of the nickel ion (at which point the pH of the bath was 6.4) and then replenished by the addition of 9 grams nickel sulfate,,9 .grams sodium hyphosphite and suflicient sodium hydroxide to raise .the pH to 10.9. The replenished bath wasjhen ,used again for furtherplating until the nickel was once more. depleted. Also, replenishment may, if desired, be on acontinuous basis so as to keep the bath-in continuous operation for an extended period.

It is to be nnderstoodthat while the-inventionhas been described chiefly by reference to particular embodiments thereof, it is not so limited since various changes and modifications may be made, all within the full and intended scope of the claims which follow.

We-claim:

1. Achemicalreduction type-nickelplating bath comprisingran aqueous-solution having an initial pH of between 7-and 11 and containing the following in the concentrations indicated:

Nickel ion From .005 to .20 mole per liter. Hypophosphite ion... From .01 to .40 mole per liter. Fluoride ion From .20 to 1.0 mole per liter. Alkyl or alkanol amine .-Suflicient to provide an N to Ni++ ratio 01 from 1:1to 10:1. Cajrlbggrylic acid or salt thereof as a Sufiicicnt to produce .a carboxyl group-to-hypophosphite ion ratio of from 1:1.to l0:1.

2. A chemical reduction type nickelplating bath comprising an aqueous-solutionhavingan initial pH of between 7 and lland containing from-.005 to .20 mole per liter nickel ion, from .01 to .40 mole-per liter hypophosphite ion, from .20 to 1.0 mole per liter fluoride ion, sutficient amine to provide an N to Ni++ ratio of from 1:1 to 10:1 and sufiicient carboxylic acid'bufier to produce a carboxyl grOUp-to-hypophosphite ion ratio of'from 1:1 to 10:1, said aminebeing selected from the group consisting of the methyl, ethyl and propyl amines, the methanol, ethanol and propanol amines and the ethylene and propylene diamines.

3. A chemical reduction type-nickel plating bath comprising an aqueous. solution having an initial pH of between 7 and 11 and containing from .005 to .20-m ole per liter nickel ion, from .01 to .40 mole per liter hypo- ;phosphite ion, from .20 to 1.0 mole per liter fluoride ion, sufficient amine to provide an N to Ni++ ratio of from ;1:1.to 10:1 and suflicient carboxylic acid buffer to pro- 4 duce a carboxyl group-to-hypophosphite ion ratio of from 1:1 to 10:1, said ,amine being selected from the group consisting of the methyl, ethyl and propyl amines, the methanol, ethanol and propanol amines and the ethylene and propylene diamines, and said butter being selected from the group consisting of acetic acid, propionic acid, succinic acid, lactic acid, glycolic acid, citric acid and the soluble saltsthereof.

4. A hemical reduction type nickel plating bath comprising an aqueous solution having an initial pH of between 7 and 11 and containing nickel sulfate sufficient to produce from .005 to .20 mole per liter nickel ion, sodium hypophosphite sufiicient to produce from .01 to .40 mole per liter hypophosphite tion, ammonium bifiuoride sufficient to produce from .20 to 1.0 mole per liter fluoride ion, triethanolamine sufficient to provide an N to Ni++ ratio of from 1:1 to 10:1 and citric acid sufficient to produce a carboxyl group-to-hypophosphite ion ratio ofirom 1:1 to 10:1.

5. A chemicalreduction type tnickel plating bath comprising an aqueous solution having an initial pH of between 7 and 11 and containing the .following in the concentrations indicated:

Nickel ion From .005 to .20 mole per liter. Hypophosphlte ion From .01 to .40 mole per liter. Fluoride ion From .20 to 1.0 mole per liter. Alkyl or elkanol amin Sufficient to provide an N to N ratio of about 5:1. Cerboxylic acid or salt thereof as a Sufficient to produce a carboxyl buiier. group-to-hypophosphite ion ratio of from 1:1 to 10:1.

6. Achemical reduction type nickel plating bath comprising an aqueous solution having an initial pH of about 8 and containing the following-in the concentrationsindicated:

Nickel sulfate grams per liter-.. 5.5 Sodium hypophosphite do 8.3 Citric acid do 10 Triethanolamine ml. per liter 20 Ammonium bifluoride grams per liter 10 7. A process for depositing nickel by chemical reduction comprising immersing the article to be plated in a bath maintained at a temperature of between and 210 F., having an initial pH of between 7 and 11 and containing the following in the'concentrations indicated:

Nickel ion From .005 to .20 mole per liter. Hypophosphite ion From .01 to .40 mole per liter. Fluoride ion From .20 to 1.0 mole per liter. Alkyl or alkanol amine Sufficient to provide an N to Ni- Nickel ion Hypophosphite ion From .01 to .40 mole per liter Fluoride ion From .20 to 1.0 mole per liter. Alkyl or alkanol amine.-. Sufficient to provide an N' to Ni++ ratio of from 1:1 to 10:1. Carboxylic acid or salt thereof as a Sufiicient to produce a carboxyl er. group-to-liypopliosphite ion ratio of from 1:1 to 10:1. 9. A process for nickel plating by chemical reduction an article made of a metal selected from the group consisting of magnesium and thorium, said process comprising immersing said article in a solution having an initial pH of between 7 and 11 and containing from .005 to .20 mole per liter nickel ion, .from .01 to .40 mole per liter hypophosphite ion, from .20 to 1.0 mole per liter fluoride ion, suflicient amine to provide. an N to Ni++ ratio of from 1:1 to 10:1 and sufficient carboxylic acid buffer to producea carboxyl grouprto-hypophosphite ion ratio of-from 1:1 to 10:1, said amine being selected from the group consisting of the methyl, ethyl and propyl amines,

the methanol, ethanol and propanol amines and the ethylene and propylene diamines.

10. A process for nickel plating by chemical reduction an article made of a metal selected from the group consisting of magnesium and thorium, said process comprising immersing said article in a solution having an initial pH of between 7 and 11 and containing from .005 to .20 mole per liter nickel ion, from .01 to .40 mole per liter hypophosphite ion, from .2 to 1.0 mole per liter fluoride ion, suflicient amine to provide an N to Ni++ ratio of from 1:1 to 10:1 and sufiicient carboxylic acid buifer to produce a carboxyl group-to-hypophosphite ion ratio of from 1:1 to 10:1, said amine being selected from the group consisting of the methyl, ethyl and propyl amines, the methanol, ethanol and propanol amines and the ethylene and propylene diamines, and said buffer being selected from the group consisting of acetic acid, propionic acid, succinic acid, lactic acid, glycolic acid, citric acid and the soluble salts thereof.

11. A process for nickel plating by chemical reduction an article made of a metal selected from the group consisting of magnesium and thorium, said process comprising immersing said article in a solution having an initial pH of between 7 and 11 and containing nickel sulfate sufiicient to produce from .005 to .20 mole per liter nickel ion, sodium hypophosphite suflicient to produce from .01 to .40 mole per liter hypophosphite ion, ammonium bifiuoride suflicient to produce from .2 to 1.0 mole per liter fluoride ion, triethanolamine sufficient to provide an N to Ni++ ratio of from 1:1 to 10:1 and citric acid sufiicient to produce a carboxyl group-to-hypophosphite ion ratio of from 1:1 to 10:1.

12. A process for nickel plating by chemical reduction an article made of a metal selected from the group consisting of magnesium and thorium, said process comprising immersing said article in a solution having an initial pH of between 7 and 11 and containing the following in the concentrations indicated:

Nickel ion From .005 to .20 mole per liter. Hypophosphite ion From .01 to .40 mole per liter. Fluoride ion From .2 to 1.0 mole per liter.

Nickel sulfate "grams per liter 5.5 Sodium hypophosphite do 8.3 Citric acid do 10 Triethanolamine ml. per liter 20 Ammonium bifluoride grams per liter 10 References Cited in the file of this patent UNITED STATES PATENTS 2,694,017 Reschan et a1. Nov. 9, 1954 2,694,019 Gutzeit Nov. 9, 1954 2,772,183 Talmey et a1. Nov. 27, 1956

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2694017 *Sep 16, 1952Nov 9, 1954Gen American Transporation CorProcess of chemical nickel plating of aluminum and its alloys and baths therefor
US2694019 *Apr 23, 1952Nov 9, 1954Gen Am TransportProcesses of chemical nickel plating and baths therefor
US2772183 *Sep 24, 1953Nov 27, 1956Gen Am TransportChemical nickel plating processes
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3121644 *Dec 15, 1961Feb 18, 1964Gen Am TransportChemical nickel plating of magnesium and its alloys
US3148072 *Sep 22, 1960Sep 8, 1964Westinghouse Electric CorpElectroless deposition of nickel
US3152009 *May 17, 1962Oct 6, 1964Dow Chemical CoElectroless nickel plating
US3373054 *Jun 18, 1964Mar 12, 1968Bayer AgChemical plating
US3418143 *Aug 15, 1967Dec 24, 1968Burroughs CorpBath for the electroless deposition of palladium
US3419419 *Feb 19, 1965Dec 31, 1968Atomic Energy Commission UsaNickel-plating bath for thorium
US3915716 *Mar 18, 1970Oct 28, 1975Schering AgChemical nickel plating bath
US4038085 *Mar 3, 1976Jul 26, 1977Chromium Industries, Inc.Method of treating electroless nickel plating bath
US4371573 *Nov 18, 1981Feb 1, 1983Siemens AktiengesellschaftElectroless deposition of nickel coatings and depositing baths therefor
US5855993 *Feb 22, 1994Jan 5, 1999International Business Machines CorporationElectronic devices having metallurgies containing copper-semiconductor compounds
DE2027404A1 *Jun 4, 1970Jan 7, 1971 Title not available
Classifications
U.S. Classification427/438, 106/1.27
International ClassificationC23C18/31, C23C18/36
Cooperative ClassificationC23C18/36
European ClassificationC23C18/36