US3060059A - Electroless nickel-phosphorous alloy plating bath and method - Google Patents
Electroless nickel-phosphorous alloy plating bath and method Download PDFInfo
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- US3060059A US3060059A US111170A US11117061A US3060059A US 3060059 A US3060059 A US 3060059A US 111170 A US111170 A US 111170A US 11117061 A US11117061 A US 11117061A US 3060059 A US3060059 A US 3060059A
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- 238000007747 plating Methods 0.000 title claims description 56
- 238000000034 method Methods 0.000 title description 21
- 229910045601 alloy Inorganic materials 0.000 title description 14
- 239000000956 alloy Substances 0.000 title description 14
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 19
- DAPUDVOJPZKTSI-UHFFFAOYSA-L ammonium nickel sulfate Chemical compound [NH4+].[NH4+].[Ni+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DAPUDVOJPZKTSI-UHFFFAOYSA-L 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 17
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 claims description 14
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 claims description 14
- 239000001509 sodium citrate Substances 0.000 claims description 12
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 12
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 11
- 239000001632 sodium acetate Substances 0.000 claims description 11
- 235000017281 sodium acetate Nutrition 0.000 claims description 11
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 claims description 10
- 229910001379 sodium hypophosphite Inorganic materials 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 35
- 229910052759 nickel Inorganic materials 0.000 description 18
- 229910052751 metal Inorganic materials 0.000 description 17
- 239000002184 metal Substances 0.000 description 17
- 230000009471 action Effects 0.000 description 13
- 229960001790 sodium citrate Drugs 0.000 description 11
- 235000011083 sodium citrates Nutrition 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 238000006722 reduction reaction Methods 0.000 description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
- 239000003638 chemical reducing agent Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- 239000004615 ingredient Substances 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 239000000872 buffer Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000010960 commercial process Methods 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 235000011056 potassium acetate Nutrition 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910001369 Brass Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000001464 adherent effect Effects 0.000 description 2
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- ZRUWFKRETRELPY-UHFFFAOYSA-N azane;nickel(2+) Chemical compound N.[Ni+2] ZRUWFKRETRELPY-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 2
- 239000004327 boric acid Substances 0.000 description 2
- 239000010951 brass Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- -1 nickel cations Chemical class 0.000 description 2
- 239000001508 potassium citrate Substances 0.000 description 2
- 229960002635 potassium citrate Drugs 0.000 description 2
- QEEAPRPFLLJWCF-UHFFFAOYSA-K potassium citrate (anhydrous) Chemical compound [K+].[K+].[K+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O QEEAPRPFLLJWCF-UHFFFAOYSA-K 0.000 description 2
- 235000011082 potassium citrates Nutrition 0.000 description 2
- 229910001380 potassium hypophosphite Inorganic materials 0.000 description 2
- CRGPNLUFHHUKCM-UHFFFAOYSA-M potassium phosphinate Chemical compound [K+].[O-]P=O CRGPNLUFHHUKCM-UHFFFAOYSA-M 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 230000001603 reducing effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
- 239000006172 buffering agent Substances 0.000 description 1
- 235000019846 buffering salt Nutrition 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- FGRVOLIFQGXPCT-UHFFFAOYSA-L dipotassium;dioxido-oxo-sulfanylidene-$l^{6}-sulfane Chemical compound [K+].[K+].[O-]S([O-])(=O)=S FGRVOLIFQGXPCT-UHFFFAOYSA-L 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- GQZXNSPRSGFJLY-UHFFFAOYSA-N hydroxyphosphanone Chemical compound OP=O GQZXNSPRSGFJLY-UHFFFAOYSA-N 0.000 description 1
- 229940005631 hypophosphite ion Drugs 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001235 sensitizing effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000007779 soft material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
- C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
- C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
- Y10T428/266—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension of base or substrate
Definitions
- This invention relates to nickel alloy plating by the socalled electroless action involving chemical reduction, to the bath and plating methods used for such action, and to the plating produced upon the receiving surface, the alloy composition of which is within the percentage range set forth hereinafter.
- This surface may be catalytic in nature or may be made so by various sensitizing procedures used to initiate the plating reaction. These commercial processes are usually of a continuous flow type, wherein the plating bath is heated in a container, and the reserve solution is contained in a reservoir. Additional reagent may be added to the reservoir during processing to replenish the active agents in the solution which are used up during plating.
- Another result desired in these plating actions is to obtain a leveling action on irregular base sheets when given a nickel alloy coating.
- Some commercial organic brighteners and leveling agents have been provided heretofore, but such organic agents function normally to produce a plate coating deposit in which the particles are deposited with tensional forces therebetween and consequently such deposits normally have poor ductility and adhesion both in the deposited material and to the base sheet or member used.
- One of such organic type nickel plating processes and baths is disclosed in Patent No. 2,819,187.
- the general object of the present invention is to provide a novel and improved plating bath for the electroless plating of nickel alloy and where the plating bath and process are characterized by the provision of improved brightness, ductility, adhesion and continuity in the plated finish obtained.
- Yet another object of the invention is to use an ammonium nickel salt in association with nickel sulfate for obtaining an improved plating bath and plating method, and where additional buffering agents are present in the atet ice
- a further object of the invention is to provide an electroless nickel plating bath and method where the initial deposit obtained is a hard, bright plate, which plate can be improved in hardness by ordinary heat treating operations and where conventional precipitation hardening action is obtained.
- Yet a further object of the invention is to provide a stress-free, continuous, non-porous nickel plate by an improved process using nickel ammonium sulfate.
- Nickel-phosphorous alloy plating will be deposited from the bath, depending on specific bath makeup, heat, pH and regularity of additions, at a rate within the thickness range of about .00045 to about .00052 inch per hour of immersion time.
- a leveling action is that a liquid honed surface, which had an initial 25 microinches of surface roughness was reduced to 18 microinches of surface roughness by a chemical deposit of nickel alloy of between 2 and 2.5 thousandths of an inch.
- Another example of a test indicating the very desirable and unusual hardness obtained by use of the chemical plating method of the invention is that a typical soft brass sample with a matt finish was nickel alloy plated in accordance with the invention. Thereafter, it was heat treated for approximately 2 hours at a temperature of 450 F. This sample, after its initial nickel plating, had a Rockwell hardness of C 50, which, after the heat treating, had increased to C 56. This additional hardness is obtained because of a conventional precipitation hardening action. However, the hardness'of C 50 on the inital plated sample gave such original soft material a very desirable shiny, hard finish. Initially the unplated sample had not appreciable reading on the Rockwell 0 scale.
- a plated brass part has no appreciable hardness reading before plating, and a reading of C 57 after plating.
- the test plating was approximately .0005" thick, and had good adhesion and flexibility through bends up to
- the ductility of the plate obtained in accordance with the invention is shown, for example, by the fact that copper foil of a thickness of .0014 inch, and weighing 1 oz. to the square foot was nickel alloy plated by the method of the invention. This nickel alloy plate was of a thickness between .0008 to .001 inch. Thereafter this copper foil plate was bent and creased over 180 many times in different directions with no indication of cracking, flaking, or peeling of the nickel alloy deposit. In other tests, the copper foil has failed before the plate deposit. A plated round bar has been bent around a member of the same diameter without any cracking or failure of the nickel plate.
- the composition or bath of the invention and particularly by the use of ammonium nickel salts, I am able to control the reducing action of the hypophosphite ion in the bath. This consequently retards the rapid and random reduction of the dissolved plating salt or salts and afiords a controlled plating action. It is believed that the nickel ammonium sulfate used in the reaction functions both as a buffer ingredient and in combination with the sodium acetate, aids in imparting brightening and leveling characteristics to the bath.
- the baths are continuously filtered to remove any precipitates forming therein.
- the addition of the nickel ammonium sulfate to the bath, where a continuous plating action is to be obtained is through some type of a liquid communication system only, preferably from a reserve supplytank or container.
- a supply container is provided and is connected to the plating bath for intermittent flow of renewal constituents thereto.
- the solid nickel ammonium sulfate is added to the supply container, as by through a filter, so that only the soluble portion of such nickel ammonium sulfate passes from the original supply barrel, or container into the plating bath.
- the plating baths are maintained, for example, by hourly, or more frequent additions of nickel sulfate, nickel ammonium sulfate, sodium hypophosphite and buffering salts as needed, from the supply container that contains plating bath ingredients corresponding to the rates of depletion of such materials in the plating action.
- Distilled water preferably preheated to about 190 F., may be directly added to maintain the plating bath level.
- the amounts for all ingredients should be varied substantially proportionally. That is, for 45 grams/liter of nickel sulfate, grams/liter of nickel ammonium sulfate, 15 grams per liter of sodium citrate, etc. or grams/ liter of nickel sulfate, 10 grams/liter of nickel ammonium sulfate, etc.
- Sodium citrate is needed in the solution because of its function as a primary buffer.
- the sodium acetate is used to reduce stresses in the nickel alloy deposit and to promote ductility and uniformity of plating, but in our bath, a novel function of this salt is attained by its combination with nickel ammonium sulfate and sodium citrate, which combination produces a grain refinement, ductility, uniformity and brightness not ordinarily found in prior formulations.
- the potassium salts may be substituted for the sodium salts listed hereinbefore.
- the process of the invention may at least be used for nickel plating iron, steel, aluminum and its alloys, copper and copper base alloys, and on nickel and nickel alloys, as well as on other metal and alloys, or plated surfaces Percent Nickel 91 to 93 Phosphorous 7 to 8.9 Carbon .02 to 1.0 Iron .02 to .10
- a bath for use in electroless nickel alloy plating comprising between about 30 to 50 grams/liter of nickel sulfate, about 10 to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/liter of sodium acetate, and about 5 to 20 grams/liter of sodium hypophosphite, the amounts of the materials used being all substantially proportionally varied within the limits stated.
- a bath for use in electrloess nickel alloy plating comprising between about 35 grams/liter of nickel sulfate, about 17.5 grams/liter of nickel ammonium sulfate, about 10 grams/ liter of sodium citrate, about 7 grams/ liter of sodium acetate, and about 10 grams/ liter of sodium hypophosphite.
- a method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 30 to 50 grams/liter of nickel sulfate, about 10 to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/ liter of sodium acetate, and about 9 to 15 grams/liter of sodium hypophosphite, and immersing an article made from the group of metals consisting of iron, steel, aluminum and its alloys, copper and its alloys, and nickel and its alloys into the bath, the bath being maintained at a pH of between about 4.8 and 5.4 and at a temperature of about F. to F., the amounts of the materials used being substantially proportionately varied Within the limits stated.
- a method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of sodiumcitrate, about 7 to 14 grams/ liter of sodium acetate, and about 9 to 15 grams/liter of sodium hypophosphite, and immersing a metal article into the bath, the bath being maintained at a pH of between about 4.8 to 5.4 and at a temperature of about 185 F. to 195 F.
- a method of nickel plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of material of the group consisting of potassium citrate and sodium citrate, about 10 to 15 grams/ liter of materials of the group consisting of potassium acetate and sodium acetate, and about 9 to 15 grams/liter of material of the group consisting of potassium hypophosphite and sodium hypophosphite, and immersing a metal article into the bath while heated until a nickel plating is obtained on the article.
- a method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 30 to 50 grams/liter of nickel sulfate, about to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/liter of a material from the group of potassium acetate and sodium acetate, and about 9 to grams/ liter of a material from the group consisting of potassium hyposulfite and sodium hypophosphite, and immersing an article made from the group of metals consisting of iron, steel, aluminum and its alloys, copper and its alloys, and nickel and its alloys into the bath, the bath being maintained at a pH of between about 4.8 to 5.4 and at a temperature of about 185 F. to 195 F.
- a method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of sodium citrate, about 7 to 14 grams/ liter of sodium acetate, and about 9 to 15 grams/ liter of sodium hypophosphite, and immersing a metal article into the bath, the bath being maintained at a pH of between about 4.8 and 5.4 and at a temperature of about 185 F. to 195 F. to obtain a plating Within the following ranges by Weight: nickel-91 to 93%, phosphorus 7 to 8.9%, carbon-.02 to 1.0%, iron .02 to .10% and only traces of other materials.
- a method of nickel plating a metal by chemical reduction comprising the steps of forming a bath from about to grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of material of the group consisting of potassium citrate and sodium citrate, about 10 to 15 grams/ liter of materials of the group consisting of potassium acetate and sodium acetate, and about 9 to 15 grams/liter of material of the group consisting of potassium hypophosphite and sodium hypophosphite, immersing a metal article into the bath until a nickel plating is obtained on the article, and replenishing the bath from a supply of the bath ingredients in solution form.
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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemically Coating (AREA)
Description
tates This invention relates to nickel alloy plating by the socalled electroless action involving chemical reduction, to the bath and plating methods used for such action, and to the plating produced upon the receiving surface, the alloy composition of which is within the percentage range set forth hereinafter.
Various commercial processes for nickel alloy plating have been proposed. In these commercial processes, the usual mode of operation is to maintain a chemical plating solution at an elevated temperature, close to the boiling point of the solution, and to immerse the object to be coated in the solution for a period of time which is suitable for the thickness of deposit'desired, ranging up to several hours. The process depends upon the reduction of nickel cations by hypophosphite anions in the presence of a catalyst, at temperatures near the boiling point of water. As is understood in the art, the cations of the dissolved salt are reduced to metal in the presence of an excess of anions from the dissolved catalyst, the other agent in the autocatalytic process being the surface upon which metal is deposited. This surface may be catalytic in nature or may be made so by various sensitizing procedures used to initiate the plating reaction. These commercial processes are usually of a continuous flow type, wherein the plating bath is heated in a container, and the reserve solution is contained in a reservoir. Additional reagent may be added to the reservoir during processing to replenish the active agents in the solution which are used up during plating.
Heretofore in the electroless plating of various base materials with nickel alloy, it has been very difficult, if not impossible to obtain uniform coverage of a ductile, but hard, bright plated finish on the desired article.
Some previous patents have suggested the use of various materials for obtaining hard, smooth and bright coatings by a nickel plating action, and one of such patents is U.S. Patent No. 2,774,688 which uses boric acid and ammonium chloride in a plating bath for obtaining a nickel deposit which can be easily buffed to have a high luster. The ammonium chloride and boric acid are supposed to produce a low stress, adherent electroless deposited plate.
Another result desired in these plating actions is to obtain a leveling action on irregular base sheets when given a nickel alloy coating. Some commercial organic brighteners and leveling agents have been provided heretofore, but such organic agents function normally to produce a plate coating deposit in which the particles are deposited with tensional forces therebetween and consequently such deposits normally have poor ductility and adhesion both in the deposited material and to the base sheet or member used. One of such organic type nickel plating processes and baths is disclosed in Patent No. 2,819,187.
The general object of the present invention is to provide a novel and improved plating bath for the electroless plating of nickel alloy and where the plating bath and process are characterized by the provision of improved brightness, ductility, adhesion and continuity in the plated finish obtained.
Yet another object of the invention is to use an ammonium nickel salt in association with nickel sulfate for obtaining an improved plating bath and plating method, and where additional buffering agents are present in the atet ice
bath to provide to the plating solution a correlated reducing bufiering action in the presence of a catalyst, or catalysts.
A further object of the invention is to provide an electroless nickel plating bath and method where the initial deposit obtained is a hard, bright plate, which plate can be improved in hardness by ordinary heat treating operations and where conventional precipitation hardening action is obtained.
Yet a further object of the invention is to provide a stress-free, continuous, non-porous nickel plate by an improved process using nickel ammonium sulfate.
The foregoing and other objects and advantages of the invention will be made more apparent as the specification proceeds.
Nickel-phosphorous alloy plating will be deposited from the bath, depending on specific bath makeup, heat, pH and regularity of additions, at a rate within the thickness range of about .00045 to about .00052 inch per hour of immersion time.
The theories of operation of the plating bath and the method of the invention are given heretofore, and tests of the plating baths are set forth hereinafter have given very desirable, improved results in the type of bond secured between the coating and the base sheet. The ductility, and brightness of the deposit have been improved greatly in relation to other known processes, and a substantially stress-free, adherent deposit has been obtained.
One example of a leveling action is that a liquid honed surface, which had an initial 25 microinches of surface roughness was reduced to 18 microinches of surface roughness by a chemical deposit of nickel alloy of between 2 and 2.5 thousandths of an inch.
Another example of a test indicating the very desirable and unusual hardness obtained by use of the chemical plating method of the invention is that a typical soft brass sample with a matt finish was nickel alloy plated in accordance with the invention. Thereafter, it was heat treated for approximately 2 hours at a temperature of 450 F. This sample, after its initial nickel plating, had a Rockwell hardness of C 50, which, after the heat treating, had increased to C 56. This additional hardness is obtained because of a conventional precipitation hardening action. However, the hardness'of C 50 on the inital plated sample gave such original soft material a very desirable shiny, hard finish. Initially the unplated sample had not appreciable reading on the Rockwell 0 scale. In another test, a plated brass part has no appreciable hardness reading before plating, and a reading of C 57 after plating. The test plating was approximately .0005" thick, and had good adhesion and flexibility through bends up to The ductility of the plate obtained in accordance with the invention is shown, for example, by the fact that copper foil of a thickness of .0014 inch, and weighing 1 oz. to the square foot was nickel alloy plated by the method of the invention. This nickel alloy plate was of a thickness between .0008 to .001 inch. Thereafter this copper foil plate was bent and creased over 180 many times in different directions with no indication of cracking, flaking, or peeling of the nickel alloy deposit. In other tests, the copper foil has failed before the plate deposit. A plated round bar has been bent around a member of the same diameter without any cracking or failure of the nickel plate.
It is believed by the use of the composition or bath of the invention, and particularly by the use of ammonium nickel salts, I am able to control the reducing action of the hypophosphite ion in the bath. This consequently retards the rapid and random reduction of the dissolved plating salt or salts and afiords a controlled plating action. It is believed that the nickel ammonium sulfate used in the reaction functions both as a buffer ingredient and in combination with the sodium acetate, aids in imparting brightening and leveling characteristics to the bath.
In using the plating baths of the invention, it will be understood that the baths are continuously filtered to remove any precipitates forming therein.
It is an important feature of the present invention that the addition of the nickel ammonium sulfate to the bath, where a continuous plating action is to be obtained, is through some type of a liquid communication system only, preferably from a reserve supplytank or container. Such a supply container is provided and is connected to the plating bath for intermittent flow of renewal constituents thereto. The solid nickel ammonium sulfate is added to the supply container, as by through a filter, so that only the soluble portion of such nickel ammonium sulfate passes from the original supply barrel, or container into the plating bath. The plating baths are maintained, for example, by hourly, or more frequent additions of nickel sulfate, nickel ammonium sulfate, sodium hypophosphite and buffering salts as needed, from the supply container that contains plating bath ingredients corresponding to the rates of depletion of such materials in the plating action. Distilled water, preferably preheated to about 190 F., may be directly added to maintain the plating bath level.
In practice of the invention, it is very desirable and necessary to control the pH of the solution within the limits of 4.8 to about 5.4.
In working with the plating bath of the invention, it has been found that the following compositions stated provide a specific bath composition, the preferred range, and the maximum range of deviation or variation in mixing quantities of the components listed and still obtain the improved plating action described:
Plating Bath pH of 4.8 to 5.4. Temperature 185 F. to
In varying the amounts of the ingredients used in the plating bath, the amounts for all ingredients should be varied substantially proportionally. That is, for 45 grams/liter of nickel sulfate, grams/liter of nickel ammonium sulfate, 15 grams per liter of sodium citrate, etc. or grams/ liter of nickel sulfate, 10 grams/liter of nickel ammonium sulfate, etc.
Sodium citrate is needed in the solution because of its function as a primary buffer. The sodium acetate is used to reduce stresses in the nickel alloy deposit and to promote ductility and uniformity of plating, but in our bath, a novel function of this salt is attained by its combination with nickel ammonium sulfate and sodium citrate, which combination produces a grain refinement, ductility, uniformity and brightness not ordinarily found in prior formulations.
In making up the baths of the invention, the potassium salts may be substituted for the sodium salts listed hereinbefore.
The process of the invention may at least be used for nickel plating iron, steel, aluminum and its alloys, copper and copper base alloys, and on nickel and nickel alloys, as well as on other metal and alloys, or plated surfaces Percent Nickel 91 to 93 Phosphorous 7 to 8.9 Carbon .02 to 1.0 Iron .02 to .10
Plus traces of aluminum, copper, silicon and/or other elements discharged into the bath from plating salts, catalysts, buffers, or surfaces being plate.
Use of nickel sulfate alone as a nickel source provides a dull, weak deposit, and use of nickel ammonium sulfate alone provides a brittle, alloy deposit. Only by use of both such materials in accord with this invention is the new and improved alloy deposit obtained.
While a certain representative embodiment and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein Without departing from the spirit or scope of the invention.
What is claimed is:
l. A bath for use in electroless nickel alloy plating and comprising between about 30 to 50 grams/liter of nickel sulfate, about 10 to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/liter of sodium acetate, and about 5 to 20 grams/liter of sodium hypophosphite, the amounts of the materials used being all substantially proportionally varied within the limits stated.
2. A bath for use in electrloess nickel alloy plating and comprising between about 35 grams/liter of nickel sulfate, about 17.5 grams/liter of nickel ammonium sulfate, about 10 grams/ liter of sodium citrate, about 7 grams/ liter of sodium acetate, and about 10 grams/ liter of sodium hypophosphite.
3. A method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 30 to 50 grams/liter of nickel sulfate, about 10 to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/ liter of sodium acetate, and about 9 to 15 grams/liter of sodium hypophosphite, and immersing an article made from the group of metals consisting of iron, steel, aluminum and its alloys, copper and its alloys, and nickel and its alloys into the bath, the bath being maintained at a pH of between about 4.8 and 5.4 and at a temperature of about F. to F., the amounts of the materials used being substantially proportionately varied Within the limits stated.
4. A method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of sodiumcitrate, about 7 to 14 grams/ liter of sodium acetate, and about 9 to 15 grams/liter of sodium hypophosphite, and immersing a metal article into the bath, the bath being maintained at a pH of between about 4.8 to 5.4 and at a temperature of about 185 F. to 195 F.
5. A method of nickel plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of material of the group consisting of potassium citrate and sodium citrate, about 10 to 15 grams/ liter of materials of the group consisting of potassium acetate and sodium acetate, and about 9 to 15 grams/liter of material of the group consisting of potassium hypophosphite and sodium hypophosphite, and immersing a metal article into the bath while heated until a nickel plating is obtained on the article.
6. A method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 30 to 50 grams/liter of nickel sulfate, about to 30 grams/liter of nickel ammonium sulfate, about 5 to 20 grams/liter of sodium citrate, about 5 to 20 grams/liter of a material from the group of potassium acetate and sodium acetate, and about 9 to grams/ liter of a material from the group consisting of potassium hyposulfite and sodium hypophosphite, and immersing an article made from the group of metals consisting of iron, steel, aluminum and its alloys, copper and its alloys, and nickel and its alloys into the bath, the bath being maintained at a pH of between about 4.8 to 5.4 and at a temperature of about 185 F. to 195 F.
7. A method of nickel alloy plating a metal by chemical reduction comprising the steps of forming a bath from about 35 to 45 grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of sodium citrate, about 7 to 14 grams/ liter of sodium acetate, and about 9 to 15 grams/ liter of sodium hypophosphite, and immersing a metal article into the bath, the bath being maintained at a pH of between about 4.8 and 5.4 and at a temperature of about 185 F. to 195 F. to obtain a plating Within the following ranges by Weight: nickel-91 to 93%, phosphorus 7 to 8.9%, carbon-.02 to 1.0%, iron .02 to .10% and only traces of other materials.
8. A method of nickel plating a metal by chemical reduction comprising the steps of forming a bath from about to grams/liter of nickel sulfate, about 15 to 25 grams/liter of nickel ammonium sulfate, about 10 to 15 grams/liter of material of the group consisting of potassium citrate and sodium citrate, about 10 to 15 grams/ liter of materials of the group consisting of potassium acetate and sodium acetate, and about 9 to 15 grams/liter of material of the group consisting of potassium hypophosphite and sodium hypophosphite, immersing a metal article into the bath until a nickel plating is obtained on the article, and replenishing the bath from a supply of the bath ingredients in solution form.
References Cited in the file of this patent UNITED STATES PATENTS 2,819,187 Gutzeit et al. Jan. 7, 1958 FOREIGN PATENTS 607,615 Canada Oct. 25, 1960 OTHER REFERENCES Metal Finishing Guidebook 1960, published by Metals & Plastics Publications, Inc. (November 23, 1959, page 453 relied on).
Claims (1)
1. A BATH FOR USE IN ELECTROLESS NICKEL ALLOY PLATING AND COMPRISING BETWEEN ABOUT 30 TO 50 GRAMS/LITER OF NICKEL SULFATE, ABOUT 10 TO 30 GRAMS/LITER OF NICKEL AMMONIUM SULFATE, ABOUT 5 TO 20 GRAMS/LITER OF SODIUM CITRATE, ABOUT 5 TO 20 GRAMS/LITER OF SODIUM ACETATE, AND ABOUT 5 TONTS OF 20 GRAMS/LITER OF SODIUM HYPOPHOSPHITE, THE AMOUNTS OFLLY THE MATERIALS USED BEING ALL SUBSTANTIALLY PROPORTIONALLY VARIED WITHIN THE LIMITS STATED.
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US111170A US3060059A (en) | 1961-05-19 | 1961-05-19 | Electroless nickel-phosphorous alloy plating bath and method |
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US111170A US3060059A (en) | 1961-05-19 | 1961-05-19 | Electroless nickel-phosphorous alloy plating bath and method |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3887732A (en) * | 1970-10-01 | 1975-06-03 | Gen Am Transport | Stress controlled electroless nickel deposits |
FR2486064A1 (en) * | 1980-07-04 | 1982-01-08 | Bacs Megyei Allami Epitoipari | PROCESS FOR COATING GLASS METAL GLASS FIBERS |
US4636255A (en) * | 1984-05-24 | 1987-01-13 | Aisin Seiki Kabushiki Kaisha | Electroless plating bath for forming a nickel alloy coating having a high phosphorus content |
US20040144285A1 (en) * | 2002-10-04 | 2004-07-29 | Enthone Inc. | Process and electrolytes for deposition of metal layers |
US20220293914A1 (en) * | 2021-03-12 | 2022-09-15 | National Cheng Kung University | Method for the fabrication of an electroless-metal-plated sulfur nanocomposite, an electroless-metal-plated sulfur cathode which is made from the nanocomposite, and a battery that uses the cathode |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2819187A (en) * | 1955-03-03 | 1958-01-07 | Gen Am Transport | Chemical nickel plating processes and baths therefor |
CA607615A (en) * | 1960-10-25 | R. Ramirez Ernest | Nickel plating |
-
1961
- 1961-05-19 US US111170A patent/US3060059A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA607615A (en) * | 1960-10-25 | R. Ramirez Ernest | Nickel plating | |
US2819187A (en) * | 1955-03-03 | 1958-01-07 | Gen Am Transport | Chemical nickel plating processes and baths therefor |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3887732A (en) * | 1970-10-01 | 1975-06-03 | Gen Am Transport | Stress controlled electroless nickel deposits |
FR2486064A1 (en) * | 1980-07-04 | 1982-01-08 | Bacs Megyei Allami Epitoipari | PROCESS FOR COATING GLASS METAL GLASS FIBERS |
US4368221A (en) * | 1980-07-04 | 1983-01-11 | Bacs Megyei Allami Epitoipari Vallalat | Process for coating fibrous glass with amorphous nickel phosphorous glass metal |
US4636255A (en) * | 1984-05-24 | 1987-01-13 | Aisin Seiki Kabushiki Kaisha | Electroless plating bath for forming a nickel alloy coating having a high phosphorus content |
US20040144285A1 (en) * | 2002-10-04 | 2004-07-29 | Enthone Inc. | Process and electrolytes for deposition of metal layers |
US7846503B2 (en) * | 2002-10-04 | 2010-12-07 | Enthone Inc. | Process and electrolytes for deposition of metal layers |
US20220293914A1 (en) * | 2021-03-12 | 2022-09-15 | National Cheng Kung University | Method for the fabrication of an electroless-metal-plated sulfur nanocomposite, an electroless-metal-plated sulfur cathode which is made from the nanocomposite, and a battery that uses the cathode |
US11996551B2 (en) * | 2021-03-12 | 2024-05-28 | National Cheng Kung University | Method for the fabrication of an electroless-metal-plated sulfur nanocomposite, an electroless-metal-plated sulfur cathode which is made from the nanocomposite, and a battery that uses the cathode |
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