CA1038326A - Aqueous acidic copper plating bath with chloride ions and sulfur compounds - Google Patents

Abstract

NOVEL PROCESSES AND COMPOSITIONS

Abstract of the Disclosure - In accordance with certain of its aspects, 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:
(A) a polysulfide compound of the formula ;

(B) a heterocyclic sulfur compound containing the grouping and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and (C) a polyether containing at least 5 ether oxygen atoms per molecule;
wherein 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 ( i ) 1 - 20 carbon atoms, or the groups -R-SO3M or -R-(S)q-RSO3M
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.

( ii )

Description

l03s~a6 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 electro-deposits.
In accordance with certain of its aspects, 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 in a concentration of 0.5 to 500 mg/l and at least one ; member from each of the following groups:
(A) a polysulfide compound of the formula R' (S)n R-so3M;

}~' ' ' , ., (B) a heterocyclic sulfur compound containing the grouping - N = C - C
S

( )Z '' and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and tC) a polyether containing at least 5 ether oxygen atoms per molecule; wherein R is independently a divalent ali-phatic 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-S03M or -R-(S)q-RS03M
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 C ~ - C~ - C - N(R"') \ N(R~)2, ~ R~ , S 2 , .

where R"' is hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl or aralkyl group, in which the additive is present in an amount sufficient to obtain a cathodic electro-deposit of bright, strongly levelled, ductile copper, and in which the process is con-tinued for a time period sufficient to obtain a cathodic electro-deposit of bright, strongly levelled, ductile copper.

103832~
The combination of these three additives in a chloride-containing copper plating bath gives unexpected beneficial effects over the use of each additive aLone in a chloride-containing copper plating bath.
Simultaneous use of at least one member from each of the three groups of additives gives bright copper deposits over a wide current density range with strong leveling properties. As used herein, the term "leveled"
denotes a surface which is smoother than its su~strate.
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) is important if strongly profiled objects are to ~e plated. The polysulfide sulfonates, as defined herein, have been found to be much more effective when employed according to the invention than the corresponding monosulfides.
When used alone these classes of additives (denoted A, B, and C herein) may be found to be deficient in one or more aspects. Thus, 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 faixly 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.

_. !

~ 10383,Z6 The 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 (~, B, and C) of the invention include the following:
T~BLE I
Sulfate Bath ~1) CUS04 5H20220 g/l) H2S0410-110 g/l (preferably about 60 ~/1) Cl5-150 mg/l (preferably about 20-80 mg/l) Fluoborate Bath

(2) cu(BF4)2100-600 g/l (preferably about 224 g/l) HBF41-60 g/l (preferably about

3.5 g/l) H3B030-30 g/l (prefer)ablY about Cl5-150 mg/l (preferably about 20-80 mg/l) The basis metals which may be electroplated in accordance with the process of this invention may include ferrous metaLs, such as steel, iron, etc., bearinz 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 pretrentment, etc.

' 1038326 After the deposition of the bright leveled copper deposit of this invention, ~enerally a ~right nickel deposit and a chromium deposit (which may be microporous or microcracked) may be applied. The ~right 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 capacity, its high luster, good ductility and low internal 6tress. It improves corrosion resistance and permits economy in nickel use.
Because of its strong Leveling properties, its very good performance at high current densities, and its very good mechanical properties (especially good ductility and low stress) the bright acid copper electrodeposit9 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 plas~ics, after the usual pretreatment.
The plating conditions for electrodeposition from the aforementioned baths may, for example, include temperatures of 10C. - 60C. (preferably 20C. - 40C.);
pH (electrometric) of less than about 2.5; and a cathode current density of .1 - 50.0 amperes per square decimeter (asd).

_ 5 _ I

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 incrèase the effective current density ranges and enhance the uniformity of the copper deposit.
In accordance with certain of its aspects, this invention relates to noveP 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:
(A) a polysulfide compound of the formula R' ~ ) R-S03M;

(B) a heterocyclic sulfur compound containing the grouping -- ~ = C -- C --t (~ I
\OJz R"
and/or tautomers thereof, . where the nitrogen atom and the two carbon atom~ are part of a heterocyclic . ring; and .
(C) a polyether containing at least 5 ether oxygen atoms per molecule;
wherein R is independently a divalent aliphaticlor aromntic non-heterocyclic group of 1 - 10 carbon ~tom~;

R' is hydrogen, a metaL cation, a monovalent aliphatic or aromatic group of 1 - 20 carbon atoms, or the groups -R-S03M or -R-(S)q-RS03M 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

4 NR"' ~ NR"' - C - C - C - N(R"' )2 N(R"' )2 R"' , S
where R"' i8 hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl or aralkyl group.
Sulfide compounds wherein n is an integer 2 - 4 are preferred. 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. -CH2-, -CH2CH2-, -~CH2)3-, -~CH2)~-, and, in general, -~CH2)p- wherein ~ is an integer 1 - 10. R may be a divalent non-heterocyclic group of 1 - 10 carbon atoms containing 1 - 3 oxygen, 1 - 3 ~ulfur, or 1 - 3 nitrogen atoms (such as -CH2CH20CH2CHz-, ~CHzOCH2CH20-CH2-~ -CH2CH2-, /=\ - /=\ /~\
-CH2 - ~ -CH2-, - ~ -, ~ -CHz-, - ~ -CH3, -CHzCHOHCH2-, -CH2CH2-NHCHzCH2-, -CHzCHzSCH2CH2-, etc.).

In the compound R~ (S)n R-S03M (1), R' may be a hydrocarbon radical preferably ~elected from 103832~;
the group consisting of alkyl, alkenyl, aLkynyl, cycloalkyl, aralkyl, aryl, alkaryl, including such radicals when inertly substituted. When R' is alkyl, it may typically be straight chain alkyl or ~ranched 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. When R' is alkeny~ 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. When R' is alkynyl, it may typically be ethynyl, propargyl, ~utynyl, etc. When R' is cycloalkyl, it may typically be cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc. When R' is aralkyl, it may typically be tolyl, xylyl, p-ethylphenyl, p-nonylphenyl, etc. R' may be inertly substituted, e.g. may bear a non-reactive su~stituent 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~ _ ~S)nM ~ R\-/ o2 ~ R' (S~n _ R-S03M (1) O
wherein R, R', M, and n are as previously defined.

~ _ I03B3a6 Specific illustrative reaction8 may include the following reactions wherein all unsubstituted carbon atoms are attached to hydrogen atom9:

~1> ~ -SSNa I CH~ - C~ -SSCHaCH~CH2SO~Na (2) CH3 (CHz)7SSK ~ (CH2)2~cH~
~SO2 ~ CH3 (CH2)7SS (CH2 )4SO3K

(3) Na2S2 ~ 2 CH2--CH~
~SO2 ~ NaO3S ~CH2 )3SS (CH2 )3SO3Na oOCH2--O
I~ONa (4) ~-SSNa +2 . CH2 4 C8 ~ CO-CH2CH2CH2-SO3Na CHi / O -SSCH2CH2CH2SO3Na 2 CH~ (CH2)3SO3H

-SSNaCH2- O / ~ -SSCH2CH2CH2SO3Na Other preparative reactions which may be u9ed to produce the 3ulfide compounds employed according to the invention include the direct sulfonation of an organo poly9ulfide (i.e. direct sulfonation of diphenyl disulfide, ditolyl di9ulfide, etc. ) . The poLy9ulfide compound9 al~o may be prepared by the reaction of epichlorohydrin and an alkali metal bisulfite followed by reaction with a polrsulfide ~6uch as Na2S2, R'SNa, wherein R' i9 as previously defined).
Other preparative reactions may include the following:
(a) SClz + 2NaS (CH2 )3 S03Na~NaO3 S (CH2 ) 3S -S -S - ~CH2 )3 S03Na (b) S2Cl2 ~ 2NaS(CH2)3SO3Na~NaO3S(CH2)3S-S-S-S-(CH2)3SO3Na (c) ClCH2CH2Cl + 2NaSS(CH2)3SO3Na ~
NaO3 S (CH2 )3 SSCH2 CH2SS (CH2 ) 3Na ~d) CLCH2CH2Cl ~ lYaSS(CH2)3SO3Na ~ NaS(CH2)3SO3Na ~
NaO3S(CH2)3SSCH2CH2S (CH2 )3SO3Na Typical polysulfide compounds which may be employed according to the invention include the following compounds which are summarized in Table II. In the formula : 15 R' (S 3nR-So3M (1) M represents a sodium cation and R, R', and N are a~
lndicated in Table II.
TABLE II
Sulfonated Polysulfide Cooperating Brighteners of the Formula R' (S ~ RSO3Na Additive R' n R
A-l ~ 2 (CH2)3 A-2 ~ 2 (CH2)3 A-3 H3C ~ 2 (CH2)3 A-4 2 (cH2)3 1~
H3C~ J

~ 038326 TABLE II cont.
Additive O n R
A-5 C~ 2 ~C~2 )3 ~CHa )aSO3Na A-6 NH~CH2 )3SO3H 2 ~CH2 )3 SO3Na H,~,~ ~C~13 A-8 NaO3 S ~CH2 ) 2 2 ~CH2 ) 2 A-9 NaO3S~CH2)3 2 ~CH2)3 A-10 NaO3S~CH2)4 2 ~CH2)4 A-ll NAO3S (CH2 )3 ~CH2 )3 A-12 ~a ~or H) 2 ~CH2 )3 A-13 NaO3S(CH2)3S2~CH2)2 2 ~CH2)3 A-14 NaO3S~CH2)3S2CH2CH = CHCH2 2 ~CH2)3 A-15 NaO3S(CH2)3S2CH2c-ccH2 - 2 ~CH2)3 A-16 NaO3S(CH2)3S2(CH2)3 2 ~CHz)3 TW IE II cont.
Additive R' n R

A-17 CH3CH2CH2CH2 2 (CH2)3 A-18 H2C=CHCH2 2 ~CH2)3 A-l9 HC_C~2 2 (CH2)3 A-20 ~ 2 (CH,~, A-21 H03 ~ 2 (CH2)3 A-22 Na03SCH2CH(OH)cH2 2 CH2CH(OH)CH2 The R'(S?nNa compound may be prepared by the reaction of R'SNa with sulfur if R' is an aromatic group , .
~compounds A-l, A-2, A-3, A-4, A-5, A-20). A typical procedure is: To a methanol solution (150 ml) containing sodium methoxide (0.1 m) is added the R'SH (0.1 m) compound.
The mixture is stirred at room temperature until the compound has dissolved. Sulfur powder (0.1 gram-equivalent) is added and the mixture stirred until all the sulfur is dissolved.
Propanesultone ~0.12 mole) is added to the stirred solution.
Stirring is continued for 30 minutes, during which time a solid precipitates from the solution. Acetone (250 ml) is then added to give additional solid, which is then ~iltered, washed with acetone, and dried.

Aliphatic R'(S)nNa compounds are prepared by reaction of R'Q ~ith Na2Sn, where Q is Cl, ~r, I, -OS02C6H~, -OS02C6H4 CH3, -OS02CH3 (e.g. compounds A-17, A-18, A-l9). 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 i8 8 lightly 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 w~ite solid usually precipitates from the solution. The mixture may be heated and stirred at 65 C. for 30 minutes and then cooled. Acetone i8 added and the solid is filtered and dried.
aompounds of the type of A-9, A-10, A-ll, A-12 are prepared by the reaction of an alkali metal polysulfide (Na2S2, Na2S4, etc.) with a sultone.
Compounds of the type of A-L3, A-14, A-15, A-16 are prepared according to the reaction sequence:
(1) QRQ ~ Na2Sz ~ NaS2RS2Na ~ 2NaQ
(2) NaS2RS2Na ~ 2fHaCH2lCH2 ~ NaO3S(CH2)3S2RS2(CH2)3S03Na.

Instead of sultones, haloalkane sulfonates, including e.g. ClCH2CIIOHCI12S03Na ~prepared by reaction of 2S epichlorohydrin with sodium bisulfite), and in general compounds of the type QRS03M, may be used.

Some poLysulEide compounds may also be prepared by the direct sulfonation of an organic polysulfide (e.g. A-7; or A-21 by sulfonation of A-20).
Symmetrical disulfides may be prepared by careful oxidation of compounds o the type HSRS03Na.
It is sometimes advantageous to prepare aqueous stock solutions o the sulfonated polysulfides containing small amounts o copper sulfate and/or sulfuric acid. Some precipitation may occur which is eliminated by filtration.
The suLfide compounds of the invention may be present in the coppeI bath in effective amounts of about 0.001 g/l - 1.0 g/l, preferably 0.005 g/l - 0.2 g/l.
The heterocyclic sulfur-containing cooperating additives o this invention contain the grouping:
a heterocyclic sulfur compound containing the grouping - N = C - C -(~ I , ' .
~ OJz R"
and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring wherein Z is 0 or 1; and R" is hydrogen, a metal ion or one of the ~roups ~ NR"' ~ NR"' c c\ - 8 - N(R"')2 N(R"' )2 ~ R"' , S

where R"' is hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl or aralkyl group.
Alternatively, the heterocyclic sulfur compound is of the formula (Y) - N
(X) - C SRl, and/or tautomers thereof, N-oxides of said compound, isothiourea derivatives, isothioamide derivatives and dithiocarbamate deriv-atives thereof where Rl is hydrogen, a metal cation, or the groups ~NR" ~NR"i - C ~ - C~ - C NR'2 NR"'2, R" , S

wherein R" is hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl, or aralkyl; X is - CR" = or - CR'2 - and Y is a divalent organogroup of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group ~X) - C = N -S

: Rl ; wherein X and Rl are as hereinbefore defined.
Certain of the above subject matter is described in our Canadian Patent No. 924,259 of April 10, 1973.

Typicnl parent substances are:
2-mercapto pyridine, 2-mercapto quinoline, 1- or 4- mercapto isoquinoline; their N-oxides; allcyl, hydroxy, alkoxy, mercapto dexivatives 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. Among the heteroaliphatic ring compounds 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 derivates 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 poly~ulfides' 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.
The heterocyclic compounds of formula group tB) may be employed in effective amounts, typically 0.1 - S0 mg/l and preferably 0.5 - 20 mg/l of total aqueous 'bath composition.
Typical heterocyclic group (B) compounds which may 'be employed accordin~ to the invention are given in Table III.

TI~BLE III
HETEROCYCI.IC COMPOUNDS (13) B FORMUIA NAr~SE

1 ~ 2-Mescaptopyridine N - SH (2-Pyridinethiol) ~ NH. HCl 2 ~ ~ ~ 2-S-Pyridyl isothiouronium -S C\ chloride 3 . ~ 2-Mercaptopyridine-SH ~l-Hydroxy-2-pyridinethione) .. O

4 ~ / NH. HCl 2-S-Pyridyl isothiouro-S-C nium chloride N-oxide . N NH2 O

~ 2-Mercapto-SH 4-methylpysidine N

6 ~ ~ . HCl 4-~Sethyl-2-S-pyridyl S-C i~othiouronium chloride ,! ~ 038326 ~ LE III ~Continued) B FOnMUL~ N~ME
__ _ Cl~3.

7 ~ 2-Mercap~o-4-~ SH metihylpyridine-N-o C~3 8 ~ NH. HCl 4-Methyl-2-S-pyridyl isothiouronium chloride ~ SC N-oxide ~,1 NH2 9 ~ 2-Mercapto-6-H3C ~ SH methylpyridine 10~ / NH. HCl 6-Methyl-2-S-pyridyl H3 ~ SC isothiouronium chloride N \ NH2 11 ~ 2-Mercapto-6-methyl N H pyridine-N-oxide o 12 ~ /~ . HCl 6-Methyl-2-S_pyrid l ~ isothiouronium H3C- ~ - S~ chloride N-oxide ~1, M~2 -- 1~ --" ~038326 T~ III (Continued) B FORMUL~ N~ME

13 ~ SH 2-Merc~ptoquinoline N

14 ~ NH. HCl 2-S-Quinolyl ~ S ~ isothiouronium chloride ~ 2-Mercaptoquinoline ~ SH N-oxide ." ~ .

16 ~ ~ NH. HCl 2-S-Quinolyl ~ SC\ N-oxide ~ NH2 17 ~ 2-Mercapto-6-hydroxy HO ~ SH pyridine N

-- 19 _ ,, TAIlLE IIT. ~Continucd) B FORMNLA N~ME
.

18~ ~ NH. HCl 6-Hydroxy-2-S-: HO~ ~,L-S pyridyl isothiouronium chloride NHz 19 ~ 2,6-Dimercapto HS ~ SH pyridine HCl.HN ~ / NH.HCl 2 ~-SS-Pyridyl C-S ~ ~ S- bis-isothiouronium / ~ \ chloride 21 ~ Thiocaprolactam __ (2-Thioxohexamethylene S imine) .

22 ~ 2-S-Pyridyl-N-S-C N(C2H5)2 diethyL dithiocarbamate S

l03s3a6 The heterocyclic cooperating additives of Table III
nre available commercially. The he~erocyclic compounds of Table III (with the exception of B-21) are generally prepared from the corresponding halogen compounds e.g. 2-chloropyridine S either by direct reaction with alkaLi metal hydrosulfide or more frequently just with thiourea joining the respective isothiouronium compounds, which may be conver~ed by alkaline hydrolysis into the corresponding mercapto compounds. B-22 was synthesized by reaction of 2- chloropyridine with sodium diethyldithiocarbamate.
Polyethers which may be used according to the process of the invention mQy-have at least S ether oxygen atoms and include polyethers of the formulae-R"'-0-Z
R"'-S-Z
R"\
N-Z
R "' R"'-N~

R""(Z)m R""(SZ)m R""(NZ)m R''''(~z )m where R"' is a monovalent radical such as H, allcyl, alkenyl, allcynyl, alkylaryl, arylallcyl or a heterocyclic radical; and - 2]

1 0 ~3~
n~ is a m- valent aliphatic, aromatic or heterocyclic radical; m=2 to 100; and %=(cuH2uo)r(cvH2vo)sT~ where u and v=0 to 4, but at least one o u or v must be greater than zero; r + s = 6 to 200,000; r=0 when u=0; s=0 when v=0;
and T = H, alkyl, benzyl, -S03M, -CuH2uSO3M, -P03H2, or CUH2UNHR ~

Suitable polyethers which may be used according to the invention include polyethers set forth in Table IV.
The polyether additives may be employed in effective amounts, typically 0.005 - 10.0 g/l and preferably 0.1 -1.0 ~/1 of total aqueous bath compositions.

TA~LE IV
Cooperatin~ Polyethers Additive 7H3 ,CH3 ~CH3 CH3 C-l CH3 - CH - CH2 - C - C _ C - C - CH2 - CH - ~l3 O O
H2 1 ~ ~H2 ¦
L o Jm l O ~n H H
m + n = 30 C-2 Formula C-l wherein m + n = 15.
C-3 Formula C-l wherein m + n = 10.

C-4 CH3 - C - CH2 - ~ - ~ - O - (CH2CH20)XH

x = 9 - 10 C-5 Formula C-4 wherein x = 30.
C-6 Formula C-4 wherein x = 40.

C-7 CgUlg- ~ _o~cHzcHso) C-8 n-Cl2H2~0(CH2CH20)2~H
~H
C-9 n-CxH2~ C - CH3 ~ N - (CH2C1l20)~
I (cH2cH2o)zH
x - 9 - 12 y ~ z = 15 _ 23 . ~0383Z6 T~nLE IV (Cont ;nucd ) Additive H(C2H40)y(c3H60)x\ ~(C3H60)X(C2H40)yH

H(CzH40~y~c3H6o)x (C3H60)X~C2H40)yH
wherein x i8 about 3 and y i9 about 3-4 C-ll HO(C2H40)XH
wherein x is about 13 C-12 HO(C2H40)xH
wherein x is about 33 C-13 HO(C3H60)xH
wherein x i9 about 6-7 C-14 HO(c3H60)x H
wherein x is about 12 C-15 CH3CH21 - CHz - CH2 - ~ - CH2CH3 O
CH2~ H

L ~H2~ L ~H2 CH2 nL ~oH2 _ n H H
wherein m = about 12 - 15 n = about 1 - 2 _ 24 103B3~6 l~LE IV (Con~inlled ) AdditiveICH3 CH3 O O
r f ~ 1 L C,U2~l 1 ,CH2 b CN2 m _ ~CIN~
H H
m = about }2 - 15 n = 1 - 2 C-17 Cl2H2ss(cH2cH20)2oH
H H
.. l, , ~
C-18 H2N - IC - CH2 ~OCH2C~p NH2 wherein p is about S - 6.
H H
C-l9 H2N - C - CH2 ~OCH2C~p NH2 wherein p i9 about 16 TABI~ IV ~Continued) Additive C-20 CH3(CH3)5CHCH3 ltc3ll6o)2 (C2H40)20H

C-2} CH3(CH2)70(c2H40)2o(c3H6o)3H

C-22 CH3(CH2)ll O(C3H60)3~C2H40)l.~H

C-23 H(OH4C2)lSO(CH2)l0 O(C2H4o)lsH

C-24 H(OC2H4)8 CH3 CH3 - (C2H40)8H

H(OH4C2 )8 CH3 ~C2H40)8H

C-25 HO(C2H40)x H
. wherein x i8 about 136 (MW i9 about 6,000) C-26 HO(C2H40)x H
wherein x is about 454 (MW is about 20,000) C-27 HO(C2H40)x H
wherein x i9 about 4540 (MW is about 200,000) ; ~038326 The chloride ion content of the aqueous copper sh~, /J
plating bath compositions of the invention ~ be at lea~t about 0.5 mg/l and~typically from 1.0 mg/l to 500 mg/l of aqueous copper plating bath. Good results may ~e obtained S using a chloride ion concentration of from about 3 mg/l to 100 mg/l of aqueous copper plating ~ath composition, and preferably a chloride ion concentration of from 20 mg/l to 80 mg/l of aqueous copper plating solution/is useJ
B Other optional additives used were the following dispersing agents:

TABLE V

Additives D-l C~z ~ SOaNa ) H H
D-2 NaO3S ~ ~ SO3Na I ~ SO3Na C--~ C--H H

SO3Na D-3 ~ SOaNa where n = 3 to 6 _ ~7 TABLE V ~Continued Additives (S03Na)n C4Hg D-4 ~ SOJNa)m n ~ m = 1 - 2 and preferably n = 0 when m = 1 CnH2n+l /CnH2n+.l D-S ~ ~ SO~M, SO3Ml wherein each n i8 an integer 4-12 (preferably 4-8) and each ~1 and M2 is an alkali metal (preferably Na or K) or a hydrogen atom.
The following examples are set forth for the ,purpose of providing those skilled-in-the-art with a better understanding of this invention, and the invention is not to be construed as limited to such examples.
In these examples the aqueous copper plating bath contains unless noted otherwise:
0 CuS04 ' SHzO 220 g/l H2S04 60 g/l chloride ion 0.06 g/l - 2~ _ 10~
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. In order to judge the degree of leveLing the polished ~rass panels used for these plating tests were scratched with 4/0 emery polishing paper over a horizontal ~and of about 10 mm. width. The plating temperature used in these experiments was the ambient room temperature (24 - 30C.), 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 15 in Ta~le IV.
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 measured as "poor", "fair", "good", and "very good" as follows:

r 10383a6 Property (1) Property (2) Rating Width of lustrous current Rating Degree of leveling . density ran~e ~__ ~ . _ _ Poor Less than one halP of Poor No visual change in _ length of test panel _ original roughness _ of scratched band _ Fair More than one half and Fair Noticeable decrease less than two thirds of _ in roughness, but length of test panel scratches still _ _ . _ visible Good More than two thirds but Good Roughness decreased _ less than entire length . and portions of . 10 of test panel scratches completely Entire length of test Very Scratches on the panel i8 lustrous G _ portion of the panel . having a current density greater than 2.5 asd. are . practically . invisible .
The combination of the panel satings given with respect to width of lustrous current density range and degree of leveling determine the final clasQification set forth in the "Results" column of Table VI according to the following:
Results Definition _ _ _ _ Excellent Very good leveling and very good bright current density .20 range Very good Very good leveling and good .bright current density range -- Good Good to very good leveling and good to very good semi-bright current density range or:
good leveling and good to very good ~right current density range Poor Poor leveling and/or poor lustrous current density range Fair All intermediate panels not otherwise cl~ssified ~;
TABLE VI

EXAMPIE AMOUNTS TYPE OF
NO. ADDITIVE g/l AGITATION RESULTS
A-l 0.02 Air Poor C-l 1.0 2 ~-1 0.02 Air Very Good C-l 1.0 B-3 0 . 006 3 A-l 0.02 Air Excellent C-l . 1.0 B-ll O. 004 4 A-l 0. 02 . Air Excellent C-l 1.0 B-12 O. 003 A-l 0.02 Mechanical Poor C-7 1.0 6 A-l 0.02 Mechanical Excellent C-7 1.0 B-5 O. 002 7 A-l 0.02 Mechanical Poor C-8 1.0 8 A-l 0.02 Mechanical Excellent C-8 1.0 B-16 O. 002 9 A-2 O. 02 Ai~ Poor C-13 1.0 A-2 0 . 02 Air Very Good B-21 O. 003 11 A-6 O. 02 Air Poor C-l 1.0 12 A-6 O. 002 Air Good C-l 1.0 B-l 0.003 13 A-6 O. 02 Air Good C-l 1.0 B-3 O. 004 ~ _ 14 A-6 O. 02 Air Very Good C-l 1.0 B-13 O. 002 A-9 O. 015 Air Poor C-13 O. 25 - , TABLE VI (Continued) EXAMPLE AMOUNTS TYPE OF
NO. ADDITIVE g/l AGITATION RESULTS
16 A-9 0.015 Air Very Good C-13 0.25 B-l 0.002 17 A-9 0.015 Air Very Good C-13 0.25 B-2 0.003 18 A-9 0.015 Air Very Good C-13 0.25 B-5 0.003 19 A-9 0.015 Air Poor C-22 1.0 A-9 0.015 Air Excellent C-~2 1.0 B-l 0.003 21 A-9 0.015 Air Very Good C-22 1.0 B-3 0.004 22 A-9 0.015 Air Excellent C-22 1.0 B-12 0.003 23 A-9 0.015 Air Good C-22 1.0 B-13 0.002 24 A-9 0.015 Air Good (less C-22 1.0 micro-roughness) B-13 0.002 D-l 0.4 A-9 o.oi5 Air Good C-22 1.0 B-14 0.020 26 A-9 0.015 Air Excellent C-22 1.0 B-16 0.002 27 A-9 0.015 Air . Excellent C-22 1.0 B-18 0.004 28 A-9 0.015 Air Good C-22 1.0 -B-19 0.002 29 A-9 0.015 Air Good C-22 1.0 B-20 0.010 - 3~ _ 10~B326 T~nlE VI (Con~inued) EXAMPLE AMOUNTS TYPE OF
NO. ADDITIVE g/l AGITATION _ESULTS
A-9 0.015 Air Excellent C-22 1.0 B-21 0.003 31 A-9 0.015 Air Excellent C-22 1.0 B-22 0.02 32 A-9 0 . 015 Air Poor C-25 0.25 33 A-9 O. 015 Air Excellent C-25 0.25 B-S 0.002 34 A-9 O. ois Air Poor C-25 1.0 A-9 0.015 Air Excellent - . C-25 1.0 B-ll 0. 004 36 A-9 O. 015 Air Good C-25 1.0 B-13 0.002 37 A-9 O. 015 Ais Poor C-27 0, 4 38 A-9 0 . 015 Air Very Good C-27 0,4 B-S 0.002 39 A-ll 0. 02 Air Poor C-10 1.0 A-ll O . 02 Air Good C-10 1.0 B-ll 0.004 41 A-ll 0. 0~ Air Good C-10 1.0 B-12 0,003 42 A-12 0.02 Air Poor C-18 1.0 43 A-12 0. 02 Air Good C-18 1 . O
B-2 0.004 - ^ ~0383Z6 T~LE VI (Contlnued) E,Y~MPLE AMOUNl'S TYPE Ol~
NO. ADDITIVE: ~/1 AGITATION RESULTS
44 A-12 O. 02 Air Cood C-18 1.0 B-18 0.008 A-15 O. 02 and 0.04 Air Poor C-15 1.0 46 A~-15 0.04 Air Very Good C-15 1.0 B-l 0.002 47 A-15 O. 02 Air Very Good C-15 1.0 B-3 0 . 004 48 A-15 0.02 Air Good C-15 1 . O
B-13 0.002 49 A-17 0.02 Air Poor C-21 1.0 : 50 A-17 0.02 Air Poor C-21 1.0 D-l 0.4 51 A-17 0.02 Air Good but C-21 1.0 . pitted B- 18 0 . 006 52 A-17 0.02 Air Very Good C-21 1.0 B-18 O. 006 D-l 0.4 53 A-18 0.02 Mechanical Poor C-6 1.0 54 A-18 0.02 Mechanical Good C-6 1.0 B-l9 O. 005 and 0.010 A-18 0. 02 Air Poor C-26 ~.0 56 A-18 0. 02 Air Good C-26 1 . O
B-l9 0.003 10383a6 Dispersin~ Agent~:

- Addition of a dispersing agent such as D-l to the A + B + C combination sometimes improves the rating by increasing the rate of leveling and/or the lustrous current density range. ~Examples 51 and 52.) S In other cases, addition of D-l does not appreciably change the rating but increases the degree of brightness or eliminates microroughness. (Examples 23 and 24.) Fluoborate Bath:

For a fluoborate bath of the preferred composition indicated in Table I, the additives of Example 35 gave equally excellent results. Use of the fluoborate bath allows to increase plating speeds by 50 to 100%.
Although this invention has been illustrated by reference to specific embodiments, modifications thereof which are clearly within the scope of the invention will be apparent to those skilled-in-the-art.

.

Claims (46)

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

1. A process for electrodepositing bright, strongly levelled, ductile copper, which comprises passing a current through an aqueous acidic copper plating bath containing chloride ions in a concentration of 0.5 to 500 mg and at least one member independently selected from each of the following groups: (A) a polysulfide compound of the formula ;

(B) a heterocyclic sulfur compound containing the grouping and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and (C) a polyether containing at least 5 ether oxygen atoms per molecule; wherein 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-SO3M or -R-(S)q-RSO3M 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:

, , wherein R"' is hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl or aralkyl group, in which the additive is present in an amount sufficient to obtain a cathodic electro-deposit of bright, strongly levelled, ductile copper, and in which the process is controlled to obtain a cathodic electro-deposit of bright, strongly levelled, ductile copper.

2. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercaptopyridine (2-pyridinethiol).

3. The process of claim 1 wherein said hetorocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride.

4. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercaptopyridine-n-oxide (1-hydroxy-2-pyridinethione).

5. The process of claim 1 wherein said heterocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride N-oxide.

6. Tho process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-4-methylpyridine.

7. The process of claim 1 wherein said heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride.

8. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-4-methylpyridine-N-oxide.

9. The process of claim 1 wherein said heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride N-oxide.

10. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-methylpyridine.

11. The process of Claim 1 wherein said heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride.

12. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-methyl pyridine-N-oxide.

13. The process of Claim 1 wherein said heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride N-oxide.

14. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-mercaptoquinoline.

15. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride.

16. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-mercaptoquinoline N-oxide.

17. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride N-oxide.

18. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-hydroxy pyridine.

19. The process of Claim 1 wherein said heterocyclic sulfur compound is 6-hydroxy-2-S-pyridyl isothiouronium chloride.

20. The process of Claim 1 wherein said heterocyclic sulfur compound is 2,6-dimercapto pyridine.

21. The process of Claim 1 wherein said heterocyclic sulfur compound is 2,6-SS-pyridyl bis-isothiouronium chloride.

22. The process of Claim 1 wherein said heterocyclic sulfur compound is thiocaprolactam (2-thioxohexamethyleneimine).

23. The process of Claim 1 wherein said heterocyclic sulfur compound is 2-S-pyridyl-N-diethyl dithiocarbamate.

24. An aqueous acidic copper plating bath containing chloride ions and at least one member independently selected from each of the following groups:
(A) a polysulfide compound of the formula ;

(B) a heterocyclic sulfur compound containing the grouping and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and (C) a polyether containing at least 5 ether oxygen atoms per molecule;

wherein 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 atoms, or the groups -R-SO3M or -R-(S)q-RSO3M 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 groupd:
, , where R''' is hydrogen, an alkyl group of 1 - 6 carbon atoms, aryl, alkaryl or aralkyl group.

25. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercaptopyridine (2-pyridinethiol).

26. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride.

27 An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercaptopyridine-n-oxide (1-hydroxy-2-pyridinethione).

28. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride N-oxide.

29. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-4-methylpyridine.

30. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride.

31. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-4-methylpyridine-N-oxide.

32. 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.

33. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6-methylpyridine.

34. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride.

35. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6-methyl pyridine-N-oxide.

36. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 6-methyl-2-S-pyridyL isothiouronium chloride N-oxide.

37. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercaptoquinoline.

38. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride.

39. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercaptoquinoline N-oxide.

40. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride N-oxide.

41. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6-hydroxy pyridine.

42. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound 6-hydroxy-2-S-pyridyl isothiouronium chloride.

43. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2,6-dimercapto pyridine.

44. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2,6-SS-pyridyl bis-isothiouronium chloride.

45. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is thiocaprolactam (2-thioxohexamethyleneimine).

46. An aqueous acidic copper plating bath as claimed in Claim 24 wherein the heterocyclic sulfur compound is 2-S-pyridyl-N-diethyl dithiocarbamate.