US3917464A - Electroless deposition of cobalt boron - Google Patents
Electroless deposition of cobalt boron Download PDFInfo
- Publication number
- US3917464A US3917464A US381121A US38112173A US3917464A US 3917464 A US3917464 A US 3917464A US 381121 A US381121 A US 381121A US 38112173 A US38112173 A US 38112173A US 3917464 A US3917464 A US 3917464A
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- United States
- Prior art keywords
- cobalt
- electroless
- bath
- boron
- deposit
- Prior art date
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- HZEIHKAVLOJHDG-UHFFFAOYSA-N boranylidynecobalt Chemical group [Co]#B HZEIHKAVLOJHDG-UHFFFAOYSA-N 0.000 title abstract description 30
- 230000008021 deposition Effects 0.000 title description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 13
- 229910017052 cobalt Inorganic materials 0.000 claims description 13
- 239000010941 cobalt Substances 0.000 claims description 13
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 13
- 239000010959 steel Substances 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 230000002195 synergetic effect Effects 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 abstract description 22
- 239000002184 metal Substances 0.000 abstract description 22
- 239000000203 mixture Substances 0.000 abstract description 8
- 239000002253 acid Substances 0.000 abstract description 6
- 150000002739 metals Chemical class 0.000 abstract description 4
- 238000005260 corrosion Methods 0.000 description 18
- 230000007797 corrosion Effects 0.000 description 18
- 239000000758 substrate Substances 0.000 description 13
- 150000003839 salts Chemical class 0.000 description 10
- 239000007921 spray Substances 0.000 description 10
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- 238000007654 immersion Methods 0.000 description 6
- KDYFGRWQOYBRFD-UHFFFAOYSA-L succinate(2-) Chemical compound [O-]C(=O)CCC([O-])=O KDYFGRWQOYBRFD-UHFFFAOYSA-L 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910000521 B alloy Inorganic materials 0.000 description 5
- 238000007772 electroless plating Methods 0.000 description 5
- 229910052763 palladium Inorganic materials 0.000 description 5
- OFNHPGDEEMZPFG-UHFFFAOYSA-N phosphanylidynenickel Chemical compound [P].[Ni] OFNHPGDEEMZPFG-UHFFFAOYSA-N 0.000 description 5
- 238000007747 plating Methods 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 229940044175 cobalt sulfate Drugs 0.000 description 3
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 3
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- -1 palladium-activated copper Chemical class 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 229940046892 lead acetate Drugs 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000615 nonconductor Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000002574 poison Substances 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 229940074404 sodium succinate Drugs 0.000 description 2
- ZDQYSKICYIVCPN-UHFFFAOYSA-L sodium succinate (anhydrous) Chemical compound [Na+].[Na+].[O-]C(=O)CCC([O-])=O ZDQYSKICYIVCPN-UHFFFAOYSA-L 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- 238000005494 tarnishing Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- WMNZZBSRXYECBA-UHFFFAOYSA-L CNC.S(=O)(=O)([O-])[O-].[Na+].[Na+] Chemical compound CNC.S(=O)(=O)([O-])[O-].[Na+].[Na+] WMNZZBSRXYECBA-UHFFFAOYSA-L 0.000 description 1
- 101100039010 Caenorhabditis elegans dis-3 gene Proteins 0.000 description 1
- 229910020674 Co—B Inorganic materials 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- KQNKJJBFUFKYFX-UHFFFAOYSA-N acetic acid;trihydrate Chemical compound O.O.O.CC(O)=O KQNKJJBFUFKYFX-UHFFFAOYSA-N 0.000 description 1
- 238000005903 acid hydrolysis reaction Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- RJTANRZEWTUVMA-UHFFFAOYSA-N boron;n-methylmethanamine Chemical compound [B].CNC RJTANRZEWTUVMA-UHFFFAOYSA-N 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- PXKJWDWAWLXQGJ-UHFFFAOYSA-N butanedioic acid hexahydrate Chemical compound O.O.O.O.O.O.C(CCC(=O)O)(=O)O PXKJWDWAWLXQGJ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 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
-
- 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
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/922—Static electricity metal bleed-off metallic stock
- Y10S428/923—Physical dimension
- Y10S428/924—Composite
- Y10S428/926—Thickness of individual layer specified
-
- 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
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/922—Static electricity metal bleed-off metallic stock
- Y10S428/9335—Product by special process
- Y10S428/936—Chemical deposition, e.g. electroless plating
-
- 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
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12771—Transition metal-base component
- Y10T428/12861—Group VIII or IB metal-base component
- Y10T428/12937—Co- or Ni-base component next to Fe-base component
-
- 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
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12986—Adjacent functionally defined components
Definitions
- This invention relates to electroless deposition and more particularly concerns improved bath compositions for the electroless deposition of cobaltboron.
- An object of the present invention is to provide an improved acid bath solution yielding an electroless cobalt-boron alloy deposit which is sound, decorative, and free of pits and cracks.
- Another object of the invention is to provide such an alloy deposit which is particularly useful in protecting basis metals against corrosive attack.
- Still another object of the invention is to provide such an alloy deposit which may readily be chromate treated to provide exceptional resistance to tarnishing.
- Yet another object of the invention is to provide such an alloy deposit which is useful for providing magnetic deposits of low coercive force.
- an improved acid electroless cobalt-boron plating bath consisting of cobalt sulfate, sodium succinate, dimethylamine borane (hereinafter referred to as DMAB), and sodium sulfate.
- the succinate prevents formation of highly stressed, cracked deposits, which characterized prior art cobalt-boron deposits made from acetate-containing solutions.
- sodium sulfate very substantially reduces pit- -ting in cobalt-boron alloy deposits.
- improved bath compositions de- DMAB 4 The bath will normally be used at a pH of about 5.0
- Electroless cobalt-boron deposition rates were only slightly affected by cobalt concentration within the range of to 45 g/l; reduced deposition rates resulted beyond those limits.
- DMAB concentration on deposition rate was determined from solutions containing g/l cobalt sulfate.7- H O and 15 g/l sodium succinate.6H O.
- the baths were adjusted to pH 5.0 with H 80 solution and were operated at 80C.
- Deposition rates increased essentially linearly with concentration to a maximum of about 4g/l. Above, this concentration, catalytic particles of cobalt formed in the solution which settled and resulted in rapid bath decomposition.
- the rate of cobalt-boron deposition increased with increasing bath temperature in a manner typical of most electroless plating baths.
- the bath was subject to spontaneous production of cobaltboron particles and rapid decomposition.
- the bath was stable during one hour plating tests. A tendency for catalytic particle formation in the bath was observed during more extended plating periods at 80C causing bath decomposition.
- the bath will be less susceptible todecomposition if trace amounts of a catalytic poison such as l to 2 mg/l of lead acetate trihydrate, or thiorea, are introduced therein.
- Deposition rates are comparatively low at bath temperatures of 40 C and lower.
- the baths are usable even at room temperatures of 22 to 27C for applying thin, electrically conductive deposits to palladium-activated nonconductors, provided the bath pH is increased to I about 6.3. u-
- v pH 5.0 and C are steel, electrolessn'ickel, palladium rate was determined from solutions containing 25 g/l i cobalt sulfate.7H O and 4 g/l DMAB'at pH 5.0"and placementdeposit of cobalt initially formed on the and gold. Alurr'iinum is spontaneously plated by a dis- 3 metal during immersion in the bath.
- Our electroless cobalt-boron alloy deposit when made from our acid bath, pH 5.0, 70C, of preferred concentrations, has the following composition, by weight:
- the coercive force of our electroless cobalt-boron deposits was generally constant, at about 8 oersteds, over the range of thicknesses tested, i.e., at 17500 to 47100 Angstroms.
- the corrosion potential of electroless cobalt-boron deposits, immersed in g/l NaCl solution for 24 hours is -0.60 volts versus the saturated calomel electrode (S.C.E.).
- steel has a corrosion potential of 0.63 volts (S.C.E.) and electroless nickelphosphorus has a corrosion potential of 0.35 volts (S.C.E.).
- Our cobalt-boron deposit, with a corrosion potential of 0.60 volts (S.C.E.) is substantially more compatible electrochemically with steel than the electroless nickel deposit having a corrosion potential of 0.35 volts (S.C.E.).
- Double-layer deposits i.e., 7.5 microns of electroless nickel and 2.5 microns of electroless cobalt-boron, on a substrate of steel were found capable of preventing basis metal attack (even at edges) after 168 hours salt spray exposure and were superior to the same total thickness of either layer alone.
- Electroless cobalt-boron deposits tarnish rapidly during salt spray exposure to produce a tenacious, mottled Corrosion Rating* Deposlt After Exposure to Salt Spray Deposit Thickness, Microns 24hrs 48hrs 7 2hrs 96hrs l68hrs Electroless Co-B 3 5 4 3+ 3(sl.E) 2(5) 5 '5 5 4 3+ 3(sl.E)
- each of the electroless cobalt-boron or nickel-phosphorus deposits were protective to steel for 48 hours salt spray exposure. With longer exposure times, the protective value of the coatings tended to improve as coating thickness increased.
- Oxide or corrosion products will now be removed from the substrate surfaces, such as by immersion in a 50% (vol) l-lCl solution.
- a 10% (vol) H 50 dip, or a chemical polishing operation is satisfactory for copper or copper alloy substrates.
- Aluminum may be immersed in 50% -(vol) HNO for removal of oxides and a thin zinc immersion deposit on aluminum by treatment in zincate solution is desirable for rapid, uniform coverage with cobalt.
- the cleaned substrate metal may now be directly immersed in our solution, or if the metal does not initiate electroless cobalt-boron deposition, then one of the steps outlined above for this class of substrates should be followed. Deposit thickness will depend, among other things, upon the amount of time the metal is permitted to remain in the bath.
- Thickness of deposit 13 microns (about 0.5 mil) EXAMPLE II Bath composition Preferred (1 mg/l lead acetate added) Substrate Copper Bath temperature C Bath pH 5.5 Deposition time l hour Thickness of deposit 25 microns (about 1.0 mil) Preferred Palladium-activated glass (glass initially abrasive blasted for better deposit adhesion) 30 min.
- a double layer deposit on steel for providing synergistic protection to said steel against corrosive attack in a saline environment comprising an initial electroless nickel-phosphorus layer and a coating thereover of electroless cobalt comprising by weight, 960% cobalt, 1.7% boron, 0.97% carbon, and 0.05% nitrogen.
- Double layer deposit as described in claim 1 further characterized by said nickel-phosphorous layer being about 7.5'microns in thickness and said electroless cobalt layer being about 2.5 microns in thickness.
Abstract
Improved electroless deposits of cobalt-boron which find particular use in protecting basis metals against corrosive attack, the deposits being prepared from an acid bath having the following preferred composition:
D R A W I N G
D R A W I N G
Description
United States Patent 1 Pearlstein et al.
[ Nov. 4, 1975 ELECTROLESS DEPOSITION OF COBALT BORON [75] Inventors: Fred Pearlstein; Robert F.
,Weightman, both of Philadelphia,
[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.
[22] Filed: July 20, 1973 [21] Appl. No.: 381,121
[52] US. Cl. 29/l96.6; 148/62; 427/438; 427/405; 427/ 131 [51] Int. Cl. C23B 3/00 [58] FieldofSearch 117/130 E, 130 8,71 M; 148/62, 6.21; 106/1; 29/1966; 204/38 B, 38
[56] References Cited UNITED STATES PATENTS 5/1959 Duvall 117/130 E X 3/1961 De Long et al.... 4/1966 Klein et a1. 148/62 X Primary Examiner-Ralph S. Kendall Assistant Examiner-Charles R. Wolfe, Jr. Attorney, Agent, or Firm-Arthur M. Suga; Nathan Edelberg; Robert P. Gibson 57 ABSTRACT I Improved electroless deposits of cobalt-boron which find particular use in protecting basis metals against corrosive attack, the deposits being prepared from an acid bath having the following preferred composition:
Cobalt sulfateJHiO Sodium succinatebH O Sodium sulfate Dimethylamine botane 2*Claims, No Drawings ELECTROLESS DEPOSITION OF COBALT BORON The invention described herein may be -manufactured, used and licensed by or for the Government for governmental purposes without the payment to. us of any royalty thereon. v
This inventionrelates to electroless deposition and more particularly concerns improved bath compositions for the electroless deposition of cobaltboron.
An object of the present invention is to provide an improved acid bath solution yielding an electroless cobalt-boron alloy deposit which is sound, decorative, and free of pits and cracks.
Another object of the invention is to provide such an alloy deposit which is particularly useful in protecting basis metals against corrosive attack.
Still another object of the invention is to provide such an alloy deposit which may readily be chromate treated to provide exceptional resistance to tarnishing.
Yet another object of the invention is to provide such an alloy deposit which is useful for providing magnetic deposits of low coercive force.
These and other objects of the invention will become apparent as the invention is further described hereinafter.
We have discovered an improved acid electroless cobalt-boron plating bath consisting of cobalt sulfate, sodium succinate, dimethylamine borane (hereinafter referred to as DMAB), and sodium sulfate. The succinate prevents formation of highly stressed, cracked deposits, which characterized prior art cobalt-boron deposits made from acetate-containing solutions. Even with the improved cobalt-boron deposits provided by succinate baths, however, pitted deposits resulted therefrom which offered only minimal resistance to corrosive attack of the basis or substrate metal. We have discovered that sodium sulfate very substantially reduces pit- -ting in cobalt-boron alloy deposits.
More specifically, improved bath compositions de- DMAB 4 The bath will normally be used at a pH of about 5.0
and about 70C.
Electroless cobalt-boron deposition rates were only slightly affected by cobalt concentration within the range of to 45 g/l; reduced deposition rates resulted beyond those limits.
DMAB concentration on deposition rate was determined from solutions containing g/l cobalt sulfate.7- H O and 15 g/l sodium succinate.6H O. The baths were adjusted to pH 5.0 with H 80 solution and were operated at 80C. Deposition rates increased essentially linearly with concentration to a maximum of about 4g/l. Above, this concentration, catalytic particles of cobalt formed in the solution which settled and resulted in rapid bath decomposition.
The effect of succinate concentration on deposition 80C. When no succinate was present, spongy cobalt formed within the solution accompanied by rapid bath decomposition and virtually no deposition was produced 'on palladium-activated copper test specimens. Satisfactory bath stability however was provided by the presence of lO g/l, up to about 30 g/l, of the succinate in the bath. The succinate also provided buffering action, i.e., prevented rapid change in bath pH during deposition. Deposition rates were highest and essentially constant at succinate hexahydrate concentrations of about 15 to 30 g/l, with about 2.5 g/l appearing to yield the best deposition characteristics.
15 g/] or more of Na SO provided effective anti-pitting characteristics to the deposits. At Na SO concentration of 10 g/l or less, pitting could be observed in the final cobalt-boron alloy deposit.
The effect of bath pH on deposition rate at 80C was determined. Deposition rate increased markedly with an increase in bath pH, but above 5.5, baths tended to be unstable and deposits formed on the walls and the bottom of the beaker.
It is interesting to note that baths at pH 4.5 and lower, increased in pH during the deposition tests, while baths at pH 5.5 and above, decreased. Normally, electroless plating baths decrease in pH during use because hydrogen ions will be formed as a product of the electroless reaction. DMAB, however, is subject to acid catalyzed hydrolysis: I (CH' HNBH +3I-l O-l-H C H NH +H BO +3H Indeed, we have found that even when no electroless plating was occurring, baths (80C) at pH 4.5 and below increased in pH with passage of time and that gassing was evident within the solutions. At bath pH of 5.0, our baths were very stable, and little or no change in pH resulted during deposition. Unless otherwise noted, all bath compositions hereinafter used and tested had a pH of 5.0.
The rate of cobalt-boron deposition increased with increasing bath temperature in a manner typical of most electroless plating baths. At 90C or above, the bath was subject to spontaneous production of cobaltboron particles and rapid decomposition. At 80C, the bath was stable during one hour plating tests. A tendency for catalytic particle formation in the bath was observed during more extended plating periods at 80C causing bath decomposition. The bath will be less susceptible todecomposition if trace amounts of a catalytic poison such as l to 2 mg/l of lead acetate trihydrate, or thiorea, are introduced therein. However, at bath temperatures of 80C and above, consumption of DMAB by hydrolysis is significantly wasteful and it is thus advisable, from a practical standpoint, to operate the bath at lower temperatures unless very high deposition rates are needed. At 70C, the bath is operable without the necessity for addition of catalytic poison stabilizers and hydrolysis losses are minimized.
Deposition ratesare comparatively low at bath temperatures of 40 C and lower. The baths are usable even at room temperatures of 22 to 27C for applying thin, electrically conductive deposits to palladium-activated nonconductors, provided the bath pH is increased to I about 6.3. u-
spontaneously initiate deposition by immersion in our preferred acid electroless cobalt-boron plating bath, at
v pH 5.0 and C, are steel, electrolessn'ickel, palladium rate was determined from solutions containing 25 g/l i cobalt sulfate.7H O and 4 g/l DMAB'at pH 5.0"and placementdeposit of cobalt initially formed on the and gold. Alurr'iinum is spontaneously plated by a dis- 3 metal during immersion in the bath.
Copper, brass, silver, platinum, titanium, stainless steels and nonconductors usually do not initiate electroless cobalt-boron deposition unless one of the following steps is taken:
a. activation of the surfaces by nucleation with a catalytically active metal such as palladium, for example.
b. contacting the metal in the electroless plating bath with an actively plating metal which initiates deposition by galvanic action.
c. momentary application of sufficient cathodic current to the metal in the electroless plating bath to apply a thin cobalt-boron film electrolytically, thus initiating deposition by electrolytic action.
Our electroless cobalt-boron alloy deposit, when made from our acid bath, pH 5.0, 70C, of preferred concentrations, has the following composition, by weight:
Co 96.0% B 1.7% C 97% N 05% Carbon and nitrogen indicate the presence of organic or organometallic compounds in the deposit.
Our electroless cobalt-boron deposits possessed a hardness of 270 kg/mm (Vickers) in the as-plated condition. After heating the deposit however, for 24 hours at 250C, hardness of the deposit increased to 480 kglmm Additional heating at 250C further increased hardness to a maximum of about 640 kg/mm after a total heating period of 4 days.
The coercive force of our electroless cobalt-boron deposits was generally constant, at about 8 oersteds, over the range of thicknesses tested, i.e., at 17500 to 47100 Angstroms.
The salt spray corrosion resistance of steel plated with our deposits is compared to that of electroless nickel-phosphorus plated steel, also highly resistant to salt spray, and, is presented in Table II below:
TABLE ll Salt Spray Exposure Test 4 Edge corrosion of the substrate was very pronounced with the electroless nickel-phosphorus plated steel whereas the electroless cobalt-boron deposits provided good resistance to substrate edge corrosion. Good edge corrosion resistance of substrate metals is vital when used in sensitive mechanisms such as fuses and other military items where any dislodging of corrosive products could readily cause serious malfunctioning. Secondarily, discoloration due to edge corrosion, incipient or advanced, might be considered aesthetically unappealing.
The corrosion potential of electroless cobalt-boron deposits, immersed in g/l NaCl solution for 24 hours is -0.60 volts versus the saturated calomel electrode (S.C.E.). In the same solution, steel has a corrosion potential of 0.63 volts (S.C.E.) and electroless nickelphosphorus has a corrosion potential of 0.35 volts (S.C.E.). Our cobalt-boron deposit, with a corrosion potential of 0.60 volts (S.C.E.) is substantially more compatible electrochemically with steel than the electroless nickel deposit having a corrosion potential of 0.35 volts (S.C.E.). Parenthetically, a deposit having a corrosion potential identical with the steel under these conditions would not accelerate corrosion of the steel substrate. Thus, our cobalt-boron deposit, having a more favorable corrosion potential than electroless nickel deposits, will tend to better resist corrosion of basis metal exposed at any coating defect or pore by adverse galvanic cell action.
A double-layer deposit of electroless nickel-phosphorus followed by a coating of electroless cobaltboron will provide synergistic protection to the basis metal because of the ability of the cobalt to sacrificially protect the nickel layer from corrosive penetration. Double-layer deposits, i.e., 7.5 microns of electroless nickel and 2.5 microns of electroless cobalt-boron, on a substrate of steel were found capable of preventing basis metal attack (even at edges) after 168 hours salt spray exposure and were superior to the same total thickness of either layer alone.
Electroless cobalt-boron deposits tarnish rapidly during salt spray exposure to produce a tenacious, mottled Corrosion Rating* Deposlt After Exposure to Salt Spray Deposit Thickness, Microns 24hrs 48hrs 7 2hrs 96hrs l68hrs Electroless Co-B 3 5 4 3+ 3(sl.E) 2(5) 5 '5 5 4 3+ 3(sl.E)
l0 5 5 5 5 3-H sl. E) Electroless NH 3 4(E) 4(E) 4 E) 3+(E) -HE) (from acid-type bath) 6 5(E) 5(E) 5( 12 5 5(E) 5(E) 5(E) 5(E) Rating: 5 no basis metal attack 4 traces of basis metal attack 3 slight basis metal attack 2 moderate basis metal attack I considerable basis metal attack E edge corrosion sl. E slight edge corrosion All results are expressed as an average of 3 tested blue-brown film. Some success was achieved in providspecimens. Salt spray exposure test is described in ASTM Designation B-l l7-64, 31 August 1964, Standard Method of Salt Spray Testing.
As is apparent from Table ll, each of the electroless cobalt-boron or nickel-phosphorus deposits were protective to steel for 48 hours salt spray exposure. With longer exposure times, the protective value of the coatings tended to improve as coating thickness increased.
ing a black non-reflective surface so often desired in military equipment by immersing the deposit for 10- minutes in a 10 g/l potassium persulfate solution at 25C.
Immersion of the cobalt-boron deposit in a solution consisting of 200 g/l Na Cr O .2H O and 6 ml/l H sp. gr. 1.84, greatly improved the resistance of the deposit surfaces to tarnishing, the surfaces remaining.
bright and untamished after 72 hours salt spray exposure. The above solution however, is mildly corrosive to the cobaltboron deposit and will remove about 0.1 micron of deposit thickness during a second immersion. No visible film is produced by this treatment.
In the production of our improved cobalt-boron alloy deposit, the following steps should be observed:
a. Remove any organic contaminants such as oils, greases, etc. from the metal substrate surfaces by soak-alkaline cleaning, or if heavy contamination exists, a vapor degrease prior to soak-alkaline cleaning may be desirable. Electro-cleaning operations may also be applied.
b. Oxide or corrosion products will now be removed from the substrate surfaces, such as by immersion in a 50% (vol) l-lCl solution. A 10% (vol) H 50 dip, or a chemical polishing operation, is satisfactory for copper or copper alloy substrates. Aluminum may be immersed in 50% -(vol) HNO for removal of oxides and a thin zinc immersion deposit on aluminum by treatment in zincate solution is desirable for rapid, uniform coverage with cobalt.
c. The cleaned substrate metal may now be directly immersed in our solution, or if the metal does not initiate electroless cobalt-boron deposition, then one of the steps outlined above for this class of substrates should be followed. Deposit thickness will depend, among other things, upon the amount of time the metal is permitted to remain in the bath.
There is set forth hereinbelow for purposes of illustration, examples of our cobalt-boron deposits prepared under varying conditions:
Thickness of deposit 13 microns (about 0.5 mil) EXAMPLE II Bath composition Preferred (1 mg/l lead acetate added) Substrate Copper Bath temperature C Bath pH 5.5 Deposition time l hour Thickness of deposit 25 microns (about 1.0 mil) Preferred Palladium-activated glass (glass initially abrasive blasted for better deposit adhesion) 30 min.
0.3 micron (approx) Bath composition Substrate Bath temperature Bath pH Deposition time Thickness of deposit We wish it :to be understood that we do not 'desire to be limited to the exact details described for obvious modifications will occur to a person skilled in the art.
We claim:
1. A double layer deposit on steel for providing synergistic protection to said steel against corrosive attack in a saline environment, said double layer deposit comprising an initial electroless nickel-phosphorus layer and a coating thereover of electroless cobalt comprising by weight, 960% cobalt, 1.7% boron, 0.97% carbon, and 0.05% nitrogen.
2. Double layer deposit as described in claim 1 further characterized by said nickel-phosphorous layer being about 7.5'microns in thickness and said electroless cobalt layer being about 2.5 microns in thickness.
Claims (2)
1. A DOUBLE LAYER DEPOSIT ON STEEL FOR PROVIDING SYNERGISTIC PROTECTION TO SAID STEEL AGAINST CORROSIVE ATTACK IN A SALINE ENVIRONMENT, SAID DOUBLE LAYER DEPOSIT COMPRISING AN INITIAL ELECTROLESS NICKEL-PHISPHOROUS LAYER AND A COATING THEREOVER OF ELECTROLESS COBALT COMPRISING BY WIGHT, 96.0% COBALT, 1.7% BORON. 0.9% CARBON, AND 0.05% NITROGEN.
2. DOUBLE LAYER DEPOSIT AS DESCRIBED IN CLAIM 1 FURTHER CHARACTERIZED BY SAID NICKEL-PHOSPHOROUS LAYER BEING ABOUT 7.5 MICRONS IN THICKNESS AND SAID ELECTROLESS COBALT LAYER BEING ABOUT 2.5 MICRONS IN THICKNESS.
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US381121A US3917464A (en) | 1973-07-20 | 1973-07-20 | Electroless deposition of cobalt boron |
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US381121A US3917464A (en) | 1973-07-20 | 1973-07-20 | Electroless deposition of cobalt boron |
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Cited By (9)
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US4055706A (en) * | 1974-07-16 | 1977-10-25 | Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) | Processes for protecting refractory metallic components against corrosion |
US4910096A (en) * | 1987-08-10 | 1990-03-20 | Hille & Muller | Cold-rolled steel strip with electrodeposited nickel coating exhibiting a great diffusion depth |
WO1992005952A1 (en) * | 1990-10-09 | 1992-04-16 | Diamond Technologies Company | Nickel-cobalt-boron alloy, implement, plating solution and method for making |
US6183546B1 (en) | 1998-11-02 | 2001-02-06 | Mccomas Industries International | Coating compositions containing nickel and boron |
WO2002099164A2 (en) * | 2001-06-01 | 2002-12-12 | Ebara Corporation | Electroless-plating solution and semiconductor device |
US20040157441A1 (en) * | 2001-06-01 | 2004-08-12 | Hiroaki Inoue | Electroless plating liquid and semiconductor device |
US20050266165A1 (en) * | 2004-05-27 | 2005-12-01 | Enthone Inc. | Method for metallizing plastic surfaces |
US20090196821A1 (en) * | 2008-02-06 | 2009-08-06 | University Of Delaware | Plated cobalt-boron catalyst on high surface area templates for hydrogen generation from sodium borohydride |
US20100291312A1 (en) * | 2007-10-22 | 2010-11-18 | National Institute For Materials Science | Electroless plating method for alloy coating film and plating liquid |
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US2975073A (en) * | 1958-02-06 | 1961-03-14 | Dow Chemical Co | Corrosion resistance of electroless nickel plate |
US3247028A (en) * | 1961-06-28 | 1966-04-19 | Bayer Ag | Processes for improving the corrosion resistance of ni-co-metal coatings containing boron |
US3338726A (en) * | 1958-10-01 | 1967-08-29 | Du Pont | Chemical reduction plating process and bath |
US3745039A (en) * | 1971-10-28 | 1973-07-10 | Rca Corp | Electroless cobalt plating bath and process |
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US2886452A (en) * | 1958-01-17 | 1959-05-12 | Gen Am Transport | Processes of regenerating chemical nickel plating solutions |
US2975073A (en) * | 1958-02-06 | 1961-03-14 | Dow Chemical Co | Corrosion resistance of electroless nickel plate |
US3338726A (en) * | 1958-10-01 | 1967-08-29 | Du Pont | Chemical reduction plating process and bath |
US3247028A (en) * | 1961-06-28 | 1966-04-19 | Bayer Ag | Processes for improving the corrosion resistance of ni-co-metal coatings containing boron |
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Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
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US4055706A (en) * | 1974-07-16 | 1977-10-25 | Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) | Processes for protecting refractory metallic components against corrosion |
US4910096A (en) * | 1987-08-10 | 1990-03-20 | Hille & Muller | Cold-rolled steel strip with electrodeposited nickel coating exhibiting a great diffusion depth |
WO1992005952A1 (en) * | 1990-10-09 | 1992-04-16 | Diamond Technologies Company | Nickel-cobalt-boron alloy, implement, plating solution and method for making |
US5213907A (en) * | 1990-10-09 | 1993-05-25 | Diamond Technologies Company | Nickel-cobalt-boron-alloy deposited on a substrate |
US5314608A (en) * | 1990-10-09 | 1994-05-24 | Diamond Technologies Company | Nickel-cobalt-boron alloy, implement, plating solution and method for making same |
US6183546B1 (en) | 1998-11-02 | 2001-02-06 | Mccomas Industries International | Coating compositions containing nickel and boron |
WO2002099164A2 (en) * | 2001-06-01 | 2002-12-12 | Ebara Corporation | Electroless-plating solution and semiconductor device |
WO2002099164A3 (en) * | 2001-06-01 | 2004-05-21 | Ebara Corp | Electroless-plating solution and semiconductor device |
US20040157441A1 (en) * | 2001-06-01 | 2004-08-12 | Hiroaki Inoue | Electroless plating liquid and semiconductor device |
US6821902B2 (en) | 2001-06-01 | 2004-11-23 | Ebara Corporation | Electroless plating liquid and semiconductor device |
US20050266165A1 (en) * | 2004-05-27 | 2005-12-01 | Enthone Inc. | Method for metallizing plastic surfaces |
US20100291312A1 (en) * | 2007-10-22 | 2010-11-18 | National Institute For Materials Science | Electroless plating method for alloy coating film and plating liquid |
US20090196821A1 (en) * | 2008-02-06 | 2009-08-06 | University Of Delaware | Plated cobalt-boron catalyst on high surface area templates for hydrogen generation from sodium borohydride |
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