Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/38—Electroplating: Baths therefor from solutions of copper

Definitions

• this invention relates to novel compositions and to a process for electrodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member independently selected from each of the following groups:
• R is independently a divalent aliphatic or aromatic non-heterocyclic group of 1-l0 carbon atom;
• R is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups -R--SC M or R(S) RSO M wherein q is an integer 2-5;
• M is a cation;
• Z is 0 or 1;
• R" is hydrogen, a metal ion or one of the groups where R is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group.
• This invention relates to novel processes and compositions for the electrodeposition of copper from aqueous acidic baths. More particularly, this invention relates to certain bath compositions containing specified combinations of chemical ingredients and to the use of such compositions to obtain bright, ductile, strongly leveled copper electrodeposits.
• a further object of the invention is to provide novel plating bath compositions from which bright copper electrodeposits may be obtained wherein said electrodeposits exhibit good leveling and ductility over wide current density ranges.
• this invention relates to novel compositions and to a process for elec- 3,804,729 Patented Apr. 16, 1974 trodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member from each of the following groups:
• R'" is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group.
• the term leveled denotes a surface which is smoother than its substrate.
• the high degree and rate of leveling leads to an important economy in finishing costs and materials.
• the improved low current density brightness i.e. the widening of the bright current density range
• the polysnlfide sulfonates, as defined herein, have been found to be much more effective when employed according to the invention than the corresponding monosul'fides.
• these classes of additives may be found to be deficient in one or more aspects.
• the copper deposits obtained may not be bright, smooth, and may not exhibit adequate leveling properties over a sufficient current density range.
• Combinations utilizing two of the additives may give fairly bright copper deposits, but the current density range of brightness may be limited and/or the rate of leveling (decrease of surface roughness) may be low.
• Other double combinations of additives may give striated deposits and limited bright current density ranges.
• novel compositions of the invention may be employed in combination with aqueous acidic copper plating baths.
• Typical aqueous acidic copper plating baths which may be employed in combination with the novel additive compositions (A, B, and C) of the invention include the following:
• the basis metals which may be electroplated in accordance with the process of this invention may include ferrous metals, such as steel, iron, etc., bearing a surface layer of nickel or cyanide copper; zinc and its alloys including zinc-base die-cast articles bearing a surface layer of cyanide copper or pyrophosphate copper; nickel, including nickel alloys with other metals such as cobalt; aluminum, including its alloys, after suitable pretreatment, etc.
• the bright leveled copper deposit of this invention After the deposition of the bright leveled copper deposit of this invention, generally a bright nickel deposit and a chromium deposit (which may be microporous or microcracked) may be applied.
• the bright acid copper deposit of this invention contributes to the appearance and performance of the composite coating because of its very high rate of leveling, its excellent pore-filling capac ity, its high luster, good ductility and low internal stress. It improves corrosion resistance and permits economy in nickel use.
• the bright acid copper electrodeposits of this invention may be used for industrial applications such as electroforming, the plating of memory drums, printing rolls, etc.
• the process gives very good results also for the plating of non-conducting materials, such as plastics, after the usual pretreatment.
• the plating conditions for electrodeposition from the aforementioned baths may, for example, include temperatures of C.-60 C. (preferably C.40 C.); pH (electrometric) of less than about 2.5; and a cathode current density of .1-50.0 amperes per square decimeter (asd).
• Typical average current densities may be 2-20 asd for the sulfate bath and about 4-40 asd for the fluoborate bath. Air agitation, volume agitation, or mechanical agitation may increase the effective current density ranges and enhance the uniformity of the copper deposit.
• this invention relates to novel compositions and to a process for electrodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member independently selected from each of the following groups:
• R is independently a divalent aliphatic or aromatic non-heterocyclic group of 1-10 carbon atoms;
• R' is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups -R-SO M or -R--(S)q-RSO M wherein q is an integer 2-5; M is a cation; Z is 0 or 1, R" is hydrogen, a
• R' is hydrogen, an alkyl group of l-6 carbon atoms, aryl, alkaryl or aralkyl group.
• R may be a divalent hydrocarbon group (including such hydrocarbon groups containing inert substituents such as hydroxyl, alkoxy, polyoxyalkylene, halogen, etc.) of 1-10 carbon atoms such as an alkylene group of 1-10 carbon atoms (i.e. CH -CH CH (CH (CH and, in general, (CH wherein p is an integer 1-1-0.
• R may be a divalent non-heterocyclic group of 1-10 carbon atoms containing 1-3 oxygen, 1-3 sulfur, or 1-3 nitrogen atoms (such as mac @wg @CH..
• R may be a hydrocarbon radical preferably selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aryl, alkaryl, including such radicals when inertly substituted.
• R When R is alkyl, it may typically be straight chain alkyl or branched alkyl, including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-amyl, neopentyl, isoamyl, n-hexyl, isohexyl, heptyls, octyls, decyls, dodecyls, etc.
• Preferred alkyl includes lower alkyl, i.e. having less than about 8 carbon atoms, i.e. octyls and lower.
• R When R is alkenyl, it may typically be vinyl, allyl, methallyl, buten-l-yl, buten-2-yl, butyn-3-yl, penten-l-yl, hexenyl, heptenyl, octenyl, decenyl, dodecenyl, tetra-decenyl, octadecenyl, etc.
• R' When R' is alkynyl, it may typically be ethynyl, propargyl, butynyl, etc.
• R When R is cycloalkyl, it may typically be cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.
• R When R is aralkyl, it may typically be tolyl, xyly, p-ethyphenyl, pnonylphenyl, etc.
• R may be inertly substituted, e.g. may bear a nonreactive substituent such as alkyl, aryl, cycloalkyl, aralkyl, alkaryl, alkenyl, ether, etc.
• Polysulfide compounds of the Formula A may typically be prepared by the reaction of an alkali metal salt of a hydropolysulfide and a sultone according to the reaction:
• R, R, M, and n are as previously defined.
• Specific illustrative reactions may include the following reactions wherein all unsubstituted carbon atoms are attached to hydrogen atoms:
• sulfide compounds employed according to the invention include the direct sulfonation of an organo polysulfide (i.e. direct sulfonation of diphenyl disulfide, ditolyl disulfide, etc.).
• the polysulfide compounds also may be prepared by the reaction of epichlorohydrin and an alkali metal bisulfite followed by reaction with a polysulfide (such as Na S- R'SNa, wherein R is as previously defined).
• Typical polysulfide compounds which may be employed according to the invention include the following compounds which are summarized in Table II.
• M represents a sodium cation and R, R, and N are as indicated in Table II.
• Aliphatic R"(S),,Na compounds are prepared by reaction of R'Q with Na s, where Q is Cl, Br, I, OSO C H OSO C H -CH OSO CH (e.g. compounds A-17, A-l8, A-19).
• a typical procedure is: To a stirred methanol solution (150 ml.) containing sodium disulfide (0.1 m.) is added dropwise a solution of R'Q (0.1 m.) in methanol (50 ml.) at room temperature. The reaction is slightly exothermic. After the addition is completed the mixture is stirred for 30 minutes. Propane sultone (0.12 m.), which may be dissolved in methanol (50 ml.), is added to the stirred mixture. During the addition of propane sultone a white solid usually precipitates from the solution. The mixture may be heated and stirred at 65 C. for 30 minutes and then cooled. Acetone is added and the solid is filtered and dried.
• Compounds of the type of A-9, A-10, A-ll, A-12 are prepared by the reaction of an alkali metal polysulfide (Na S Na S etc.) with a sultone.
• an alkali metal polysulfide Na S Na S etc.
• haloalkane sulfonates including e.g. ClCH- CHOHCH SO Na (prepared by reaction of epichlorohydrin with sodium bisulfite), and in general compounds of the type QSRO M, may be used.
• Some polysulfide compounds may also be prepared by the direct sulfonation of an organic polysulfide (e.g. A-7; or A-21 by sulfonation of A-).
• an organic polysulfide e.g. A-7; or A-21 by sulfonation of A-.
• Symmetrical disulfides may be prepared by careful oxidation of compounds of the type HRSO Na.
• the sulfide compounds of the invention may be present in the copper bath in effective amounts of about 0.001 g./l.-1.0 g./l., preferably 0.005 g./l.0.2 g./l.-0.2 g./l.
• heterocyclic sulfur-containing cooperating additives of this invention contain the grouping:
• heterocyclic sulfur compound containing the grouping -N- -e l l g, l CODZ n and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring wherein Z is O or 1;
• R is hydrogen, a metal ion or one of the groups and/or tautomers thereof, N-oxides of said compound, isothlourea derivatives, isothioamide derivatives and di- 8 v thiocarbamate derivatives thereof where R; is hydrogen, a metal cation, or the groups NRlfzI RI!
• R" is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl, or aralkyl;
• Typical parent substances are: Z-mercapto pyridine, 2- mercapto quinoline, 1- or 4-mercapto isoquinoline; their N-oxides; alkyl, hydroxy, alkoxy, mercapto derivatives of these compounds derived by substitution on the ring carbon atoms; isothioureas, isothioamides and their salts with acids, dithiocarbomates derived by substitution on the bivalent sulfur atom.
• thiocaprolactam gives especially good results.
• the mercapto compounds may be dissolved before addition to the copper bath in water containing equivalent amounts of alkali hydroxides, in dilute acids or in suitably organic solvents, e.g. alcohols.
• the isothiourea, isothioamide, dithiocarbamate derivatives are dissolved in water, dilute acids or in suitable solvents such as alcohols, but not in alkali hydroxides as they may decompose therein.
• the function of the heterocyclic compounds of group (B) is to produce, in conjunction with the sulfonated polysulfides of group (A) and the polyethers of group (C), leveling and to increase the brightness of the deposits obtained, especially in the low and medium current density range.
• heterocyclic compounds of formula group (B) may be employed in effective amounts, typically 0.1-50 mg./l. and preferably 0.5-20 mg./l. of total aqueous bath composition.
• Typical heterocyclic group (B) compounds which may be employed according to the invention are given in Table III.
• the heterocyclic cooperating additives of Table III are 0 available commercially.
• the heterocyclic compounds of 12 Table III with the exception of B-21) are generally prepyrldyl pared from the corresponding halogen compounds, e.g. NH'HCI g flz f gg 2-chloropyridine either by direct reaction with alkali metal mcs0 N-oxlde. hydrosulfide or more frequently just with thiourea join- N NE, ing the respective isothiouronium compounds, which may 1 be converted by alkaline hydrolysis into the corresponding 0 mercapto compounds.
• Polyethers which may be used according to the process of the invention may have at least 5 ether oxygen atoms V-SH and include polyethers of the formulae:
• Suitable polyethers which may be used according to the invention include polyethers set forth in Table IV.
• the polyether additives may be employed in eflective amounts, typically 0.005-10.0 g./l. and preferably 0.1-1.0 g./l. of total aqueous bath compositions.
• the chloride ion content of the aqueous copper plating bath compositions of the invention may be at least about 0.5 mg./l. and typically from 1.0 mg./l. to 500 mg/l. of aqueous copper plating bath. Good results may be obtained using a chloride ion concentration of from about 3 mg/l. to 100 mg./l. of aqueous copper plating bath composition, and preferably a chloride ion concentration of from 20 mg./l. to mg./l. of aqueous copper plating solution.
• aqueous copper plating bath contains unless noted otherwise:
• the plating experiments were performed in a Hull Cell containing 250 ml. of this acid copper sulfate bath.
• the Hull Cell allows one to observe the appearance of the deposit over a wide current density range.
• the plating temperature used in these experiments was the ambient room temperature (24-30 C.), unless otherwise stated.
• the total current was 2 amperes and the plating time 10 minutes.
• Air agitation or mechanical agitation with an oscillating paddle was used as specified in Table VI.
• the sulfonated polysulfide compounds used are described in Table II, the heterocyclic sulfur compounds in Table III, and the polyethers in Table IV.
• Table VI For convenience, the results shown in Table VI are classified according to (1) the width of the lustrous current density range (semi-bright to bright) and according to (2) the degree of leveling under the indicated experimental conditions (i.e. a 250 ml. Hull Cell, 2 amperes current, and a ten minute plating time on a metal strip having a band uniformly scratched with 4/0 grit emery paper).
• Each property in groups (1) and (2) is independently Property (1) Rating-.- Width of lustrous current density range Poor Less than one half of Poor No visual change in length of test panel. original roughness of scratched band. Fair More than one half and Falr...-- Noticeable decrease in less than two thirds roughness, but of length of test panel. scratches still visible. Good-.... More than two thirds Good. Roughness decreased but less than entire and portions of length of test panel. scrailzches completely eve Very Entire length of test Very Scratches on the portion good. panel ISIUSUOHS. good. of the panel having a current density greater than 2.5 asd. are practically invisible.
• Example Amounts Type of Example Amounts, Type of number Additive g./l. agitation Results number Additive g./l. agitation Results 1 ⁇ A-l Air Poor. A-11 0.02 Air. Good.
• Dispersing agents 20 :3 15131: ig gf" Addition of a dispersing agent such as D-l to the B-1 0.003 Air Do A B C corn on om i es im 1' ve the ratin b A-9 0.015 Air Very good bmatl s p O s g y 21 M Mr increasing the rate of leveling and/or the lustrous current -3 0004 r density range (Examples 51 and 52 A-9 22 ⁇ C-22 0 i 1 iii----. Emelggflt In other cases, addition of D-l does not appreciably (W03 change the rating but increases the degree of brightness A-9 0.015 Air Good. 23 M pm or eliminates microroughness. (Examples 23 and 24.)
• R is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group
• X is CR": or CR
• Y is a divalent organo group of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group wherein X and R" are as hereinbeforedefined.
• heterocyclic sulfur compound is Z-mercaptopyridine (Z-pyridinethiol).
• heterocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride.
• heterocyclic sulfur compound is Z-mercaptopyridine-n-oxide (l-hydroxy-2-pyridinethione).
• heterocyclic sulfur compound is 2-S-p'yridyl isothiouronium chloride N-oxide.
• heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride.
• heterocyclic sulfur compound is 2-mercapto-4-methylpyridine-N-oxide.
• heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride N-oxide.
• heterocyclic sulfur compound is 2-mercapto-6-methylpyridine.
• heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride.
• heterocyclic sulfur compound is 2-mercapto-6-methyl pyridine-N- oxide.
• heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride N-oxide.
• heterocyclic sulfur compound is Z-mercaptoquinoline N-oxide.
• heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride N-oxide.
• heterocyclic sulfur compound is 2-mercapto-6-hydroxy pyridine.
• heterocyclic sulfur compound is 6-hydroxy-2-S-pyridyl isothiouronium chloride.
• heterocyclic sulfur compound is 2,6-SS-pyridyl bis-isothiouronium chloride.
• heterocyclic sulfur compound is Z-S-pyridyl-N-diethyl dithiocarbamate.
• R is independently a divalent aliphatic or aromatic non-heterocyclic group of 11() carbon atoms, n is an integer 24; R is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups R-SO M or -R-(S)q-RSO M wherein q is an integer 2-5; M is a cation; R is hydrogen, a metal ion or one of the groups:
• R is hydrogen, an alkyl group of 1- 6 carbon atoms, aryl, alkaryl or aralkyl group;
• Y is a divalent organo group of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group wherein X and R" are as hereinbefore defined.
• An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride N-oxide.
• An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 6-methyl-2-SPpyridyl isothiouronium chloride N-oxide.
• An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-S-pyridy1-N-diethyl dithiocarbamate.

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• 1972
  • 1972-06-19 US US00264193A patent/US3804729A/en not_active Expired - Lifetime
• 1973
  • 1973-05-23 JP JP5765773A patent/JPS5727189B2/ja not_active Expired
  • 1973-05-29 CA CA172,595A patent/CA1038326A/en not_active Expired
  • 1973-05-30 AR AR248296A patent/AR200018A1/es active
  • 1973-06-05 GB GB2685273A patent/GB1433039A/en not_active Expired
  • 1973-06-06 ZA ZA733838A patent/ZA733838B/xx unknown
  • 1973-06-18 BR BR4502/73A patent/BR7304502D0/pt unknown
  • 1973-06-18 IT IT9504/73A patent/IT988460B/it active
  • 1973-06-19 FR FR7322212A patent/FR2190943B1/fr not_active Expired
  • 1973-06-19 DE DE2331180A patent/DE2331180C2/de not_active Expired
  • 1973-06-19 NL NL7308515A patent/NL7308515A/xx not_active Application Discontinuation

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