U.S. patent application number 11/105947 was filed with the patent office on 2006-11-23 for method for electrodeposition of bronzes.
This patent application is currently assigned to Enthone Inc.. Invention is credited to Joachim Heyer, Marlies Kleinfeld, Stefan Schafer, Ortud Steinius, Katrin Zschintzsch.
Application Number | 20060260948 11/105947 |
Document ID | / |
Family ID | 37115474 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260948 |
Kind Code |
A2 |
Zschintzsch; Katrin ; et
al. |
November 23, 2006 |
METHOD FOR ELECTRODEPOSITION OF BRONZES
Abstract
Abstract of the Disclosure A method for electrodeposition of
bronzes, with which the substrate to be coated is plated in an acid
electrolyte that contains at least tin and copper ions, an
alkylsulfonic acid and a wetting agent, and the preparation of such
an electrolyte.
Inventors: |
Zschintzsch; Katrin;
(Solingen, DE) ; Heyer; Joachim;
(Neunkirchen-Seelscheid, DE) ; Kleinfeld; Marlies;
(Wuppertal, DE) ; Schafer; Stefan; (Solingen,
DE) ; Steinius; Ortud; (Wuppertal, DE) |
Correspondence
Address: |
SENNIGER POWERS
ONE METROPOLITAN SQUARE
16TH FLOOR
ST LOUIS
MO
63102
US
|
Assignee: |
Enthone Inc.
350 Frontage Road
West haven
CT
06516
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20050263403 A1 |
December 1, 2005 |
|
|
Family ID: |
37115474 |
Appl. No.: |
11/105947 |
Filed: |
April 14, 2005 |
Current U.S.
Class: |
205/241 |
Current CPC
Class: |
C25D 3/58 20130101; C25D
3/60 20130101 |
Class at
Publication: |
205/241 |
International
Class: |
C25D 11/20 20060101
C25D011/20 |
Claims
1. A method for electrolytic deposition of bronze onto a substrate,
the method comprising: immersing a substrate in an aqueous acidic
electrolyte containing: a) tin ions; b) copper ions; c) an
alkylsulfonic acid; and d) a nonionic wetting agent selected from
the group consisting of aliphatic nonionic wetting agents,
substituted dithioglycols, and combinations thereof.
2. The method of claim 1 wherein the alkylsulfonic acid is present
in the electrolyte at a concentration of from 140 to 382 g/L of
electrolyte.
3. The method of claim 1 wherein the alkylsulfonic acid comprises
methanesulfonic acid in a concentration of at least about 290
g/L.
4. The method of claim 1 wherein the electrolyte further contains
an oxidation inhibitor.
5. The method of claim 1 wherein the electrolyte further contains a
dihydroxybenzene compound as an oxidation inhibitor.
6. The method of claim 1 wherein the bronze deposited onto the
substrate comprises at least about 60% by weight Cu.
7. The method of claim 1 wherein the nonionic wetting agent is
present in the electrolyte at a concentration of from about 2 to
about 40 g/L.
8. The method of claim 1 wherein tin methanesulfonate is present in
the electrolyte in an amount of from about 5 to about 195 g/L of
electrolyte, thereby providing the tin ions at a concentration of
from about 2 to about 75 g/L of electrolyte.
9. The method of claim 1 wherein copper methanesufonate is present
in the electrolyte in an amount of from about 8 to about 280 g/L of
electrolyte, thereby providing the copper ions at a concentration
of from about 2 to about 70 g/L of electrolyte.
10. The method of claim 1 wherein the electrolyte has a pH of less
than about 1.
11. The method of claim 1 wherein the nonionic wetting agent
comprises an aliphatic fatty alcohol ethoxylate.
12. The method of claim 1 wherein the nonionic wetting agent
comprises the substituted dithioglycols.
13. An aqueous acidic electrolyte containing: a) tin ions; b)
copper ions; c) an alkylsulfonic acid; and d) a nonionic wetting
agent selected from the group consisting of aliphatic nonionic
wetting agents, substituted dithioglycols, and combinations
thereof.
14. The electrolyte of claim 13 wherein the alkylsulfonic acid is
present at a concentration of from about 140 to about 382 g/L of
electrolyte.
15. The electrolyte of claim 13 wherein the alkylsulfonic acid
comprises methanesulfonic acid in a concentration of at least about
290 g/L.
16. The electrolyte of claim 13 further containing an oxidation
inhibitor.
17. The electrolyte of claim 13 further containing a
dihydroxybenzene compound as an oxidation inhibitor.
18. The electrolyte of claim 13 wherein the nonionic wetting agent
is present in the electrolyte at a concentration of from about 2 to
about 40 g/L of electrolyte.
19. The electrolyte of claim 13 wherein the tin ions are present at
a concentration of from about 2 to about 75 g/L of electrolyte, and
the copper ions are present at a concentration of from about 2 to
about 70 g/L of electrolyte.
20. The electrolyte of claim 13 wherein the aliphatic nonionic
wetting agent comprises an aliphatic fatty alcohol ethoxylate.
21. The electrolyte of claim 13 wherein the nonionic wetting agent
is the substituted dithioglycol.
22. The electrolyte of claim 21 wherein the substituted
dithioglycol is selected from the group consisting of
Thiobis(diethyleneglycol), Thiobis(hexaethylene glycol),
Thiobis(pentadecaglycelol), Thiobis(icosaethyleneglycol),
Thiobis(pentacontaethyleneglycol),
4,10-dioxa-7-thiatridecane-2,12-diol, Thiodiglycerin,
Thiobis(triglycerin),
2,2'-Thiodibutanolbis(octaethyleneglycolpentaglycerol) ether,
Thiobis(octaethyleneglycol)bis(2-chloroethyl)ether,
Thiobis(decaethyleneglycol)bis(carboxymethyl)ether,
Thiobis(dodecaethyleneglycol)bis(2-nitroethyl)ether,
Thiodiglycolbis(carboxymethyl)ether,
Dithiodiglycolbis(carboxymethyl)ether,
Thiobis(dodecaethyleneglycol),
Dithiobis(hentetracontaethyleneglycol),
Dithiobis(icosaethyleneglycolpentapropyleneglycol),
Dithiobis(triglycerol), Dithiobis(decaglycelol),
3,6-Dithiaoctane-1,8-diol,
1,3-Propanedithiolbis(decaethyleneglycol)thioether,
1,4-Buthanedithiolbis(pentadecaglycerol)thioether,
1,3-Dithioglycerolbis(pentaethyleneglycol)thioether,
1,2-Ethanedithiolbis(penta(1-ethyl)ethyleneglycol)thioether,
1,3-Dithioglycerolbis(di(1-ethyl)ethyleneglycol)thioether,2-Mercaptoethyl-
sulfide bis(hexatriacontaethylene-glycol),
2-Mercaptoethylsulfidebis(icosaethyleneglycol)di-methylether,
2-Mercaptoethyletherbis(diethyleneglycol),
Thiodiglyceroltetra(decaethyleneglycol)ether,Diethyleneglycolmonomethylth-
ioether, Decaglycerolmono(6-methylthiohexyl)thioether,
2-Mercaptoethylsulfide-.omega.-{(2-bromoethyl)
icosaethyleneglycol}thioether-.omega.'-{(2-bromoethyl)
hectaethyleneglycol}thioether,
1,4-Butanediol-.omega.-{(2-benzyloxy-1-methyl)ethyl}thioether-.omega.'-(d-
e capropyleneglycoloctacontaethyleneglycol)thioether,
Dithiobis(icosaethyleneglycol)bis(2-methyl-thioethyl)ether,
1,2-Ethanediol-.omega.-(4-methoxybenzyl)thioether-.omega.'-(pentacontaeth-
yleneglycol)thioether,
Triacontaethyleneglycolmono(4-cyanobenzyl)thioether,
Thiobis(pentadecaethyleneglycol)bisallylether,
Tricosaethyleneglycolmono(4-formylphenetyl)thioether,
Pentadecaethyleneglycolmono{(acetylmethyl)thioethyl}thioether,
1,2-Ethanediol-.omega.-(glycidyl)thioether-.omega.'-icosaethyleneglycolth-
ioether, Octadecaethyleneglycolbis(2-methylthioethyl)ether,
Hexadecaethyleneglycolmono(2-ethylthioethyl)thioether,
Icosaethyleneglycolmonomethylthioether,
Undecaethyleneglycoldi(n-propyl)thioether,
Dodecaethyleneglycolbis(2-hydroxyethyl)thioether,
Undecaethyleneglycoldimethylthioether,
Pentatriacontaethyleneglycolmono(2-n-butyldithioethyl)dithioether,
4,8,12-trithiapentadecane-1,2,6,10,14,15-hexaol,
Icosaglycerolmono(2-ethylthioethyl)thioether,
Triacontaethyleneglycolmono(2-methylthioethyl)thioether,
Dithiobis(icosaethyleneglycol)dibenzylether,
Tridecaethyleneglycolmonomethylthioether, Hexadecaethyleneglycol
dimethylthioether,
1,2-Ethanedithiolbis(icosaethyleneglycol)thioether,
Dithiobis(pentadecaethyleneglycol), 3,3'-thiodipropanol, and
combinations thereof.
23. The electrolyte of claim 13 further containing a gluconate.
24. The electrolyte of claim 13 further containing
hydroquinone.
25. The electrolyte of claim 13 having a pH of less than 1.
26. An aqueous acidic electrolyte containing: a) divalent tin ions
at a concentration of from about 2 to about 75 g/L of electrolyte;
b) divalent copper ions at a concentration of from about 2 to about
70 g/L of electrolyte; c) an aromatic, nonionic wetting agent at a
concentration of from about 2 to about 40 g/L of electrolyte; d) a
stabilizer, complexing agent, or mixture thereof at a concentration
of less than about 50 g/L of electrolyte; e) a wetting agent
selected from the group consisting of an anionic wetting agent, a
nonionic, aliphatic wetting agent, and mixtures thereof at a
concentration of less than about 10 g/L of electrolyte; f) an
oxidation inhibitor at a concentration of less than about 5 g/L of
electrolyte; g) a brightener at a concentration of less than about
5 g/L of electrolyte; and h) an alkylsulfonic acid at a
concentration of at least about 140 g/L of electrolyte.
27. The electrolyte of claim 26 wherein the alkylsulfonic acid
comprises methanesulfonic acid in a concentration of at least about
290 g/L.
Description
Detailed Description of the Invention
FIELD OF THE INVENTION
[0001] This invention concerns a method for electrodeposition of
bronzes, with which the substrate to be coated is plated in an acid
electrolyte that contains at least tin and copper ions, an
alkylsulfonic acid and a wetting agent, and the preparation of such
an electrolyte.
BACKGROUND OF THE INVENTION
[0002] Methods for deposition of tin and tin alloys on the basis of
various types of electrolytes are known from the prior art and are
already widely used in practice. Methods for deposition of tin
and/or tin alloys from cyanide electrolytes are very common. Such
electrolytes, however, are highly toxic, which makes their use
problematic from the environmental standpoint, so that for some
years there has been a push to develop cyanide-free electrolytes,
for example electrolytes based on pyrophosphates or oxalates, which
operate in a pH region of 5-9. However, such methods have both
economic and technical disadvantages, of which the relatively slow
deposition rates may be mentioned here.
[0003] For these reasons development is currently going mostly in
the direction of making available methods for deposition of tin
and/or tin alloys from acid electrolytes, since, for one thing,
divalent tin can be very easily reduced to metallic tin in acid
electrolytes, which leads to better deposition rates while having
qualitatively equivalent coatings, and for another the
disadvantageous effect of alkaline electrolytes on substrates, for
example ceramic structural elements, is prevented by this.
[0004] Thus, acid electrolytes and methods for deposition of
qualitatively high grade tin or tin alloys with a higher deposition
rate are known from EP 1 111 097 A2 and US 6,176,996 B1. These are
electrolytes that contain at least two divalent metal salts of an
organic sulfonic acid and from which are deposited solderable and
corrosion resistant coatings that can be used, for example, as
substitutes for lead-containing solderable coatings in electronics
for manufacture of circuit boards, etc.
[0005] However, such methods have their limits in the deposition of
tin-copper alloys with high copper contents, such as the so-called
"true" bronzes, which have a copper content of at least 10%. For
example, due to the high difference of potential between tin and
copper higher rates of oxidation of the divalent tin can occur, due
to which it very easily becomes oxidized to tetravalent tin in acid
electrolytes. However, in this form tin can no longer be
electrolytically deposited in an acid and thus is withdrawn from
the process, which leads to uneven deposition of the two metals and
to a decrease of the deposition rate. In addition, oxidation to
tetravalent tin leads to increased sludge formation, which can
prevent stable operation and long lifetime of the acid electrolyte.
Moreover, because of such contaminated of a firmly bonding and
pore-free coating is no longer guaranteed.
[0006] Because of such technical process disadvantages, there is
currently no large area of use for electrolytically deposited
bronze coatings. Occasionally bronze coatings are used in the
jewelry industry as a substitute for expensive silver or
allergy-triggering nickel. In the same way methods for
electrodeposition of bronzes are also gaining importance in some
technical fields, for example in electronics for coating electronic
components or in mechanical engineering and/or in process
technology for coating bearing overlays and friction layers.
However, in this case chiefly white bronzes or the so-called "false
bronzes," whose copper content can be kept quite low due to process
conditions, are deposited as nickel substitutes.
SUMMARY OF THE INVENTION
[0007] Therefore, the invention is based on the task of providing a
method for deposition of bronzes that, in contrast to the methods
known from the prior art, enables uniform deposition of at least
tin and copper side by side from an acid electrolyte at
considerably higher deposition rates. Moreover, with this method
firmly bonding and pore-free bronze coatings with high copper
contents as well as various decorative and mechanical properties
are said to be deposited.
[0008] In addition, an acid electrolyte that can have a high
content of divalent copper ions, is stable with respect to
oxidation-caused sludge formation, and is both economical and
environmentally friendly when used over a long period of time, is
to be made available.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The task is solved in accordance with the invention by a
method of the kind mentioned at the start, which is characterized
by the fact that an aromatic, nonionic wetting agent is added to
the electrolyte.
[0010] With this invention a method for electrodeposition of
bronzes is made available, where an anode of a copper-tin alloy and
a cathode are connected to the substrate that is to be coated by
means of an electrolyte, and coating takes place by passing a
direct current through them. In addition, with the invention an
electrolyte that is usable in particular for this method and the
coatings that are obtainable by this method are made available.
[0011] Through the method in accordance with the invention the
disadvantages known in the prior art are remedied with the offering
of a new electrolyte composition and in this way considerably
better deposition results are achieved. Moreover, the conduct of
the method is made to be simpler and more economical. This, too, is
chiefly based on the advantageous composition of the electrolyte.
For example, the method is carried out at room temperature, or
between 17 and 25 C, and the substrate to be coated is plated in a
highly acid environment at a pH <1. The electrolyte is
particularly stable in this temperature range. In addition, there
are no longer any costs for heating the electrolyte and the plated
substrates also do not have to be cooled very much, with large
expenditures of time and money. Moreover, deposition rates of 0.25
m/min at a current density of 1 A/dm.sup.2 are achieved due to,
among other things, the pH value and the advantageous addition of
at least one aromatic non-ionic wetting agent. By increasing the
metal content this rate can be raised up to 7 A/dm.sup.2 in rack
operation and even up to 120 A/dm.sup.2 for continuous plants.
Thus, usable current densities in a range from 0.1-120 A/dm.sup.2
are reached in each case according to plant type.
[0012] Surprisingly, the wetting of the surfaces to be plated,
above all those of more complex substrates, is considerably
improved in particular through the addition of at least one
nonionic wetting agent to the electrolyte. This advantageously has
the result that not only are the considerably higher deposition
rates achieved through the use of the method in accordance with the
invention, but moreover the coatings produced by the method are
uniform and qualitatively high grade, have very good adhesion and
are generally pore-free.
[0013] Another advantage of the nonionic wetting agent that is used
is that because of the advantageous wetting properties the
electrolyte and/or the substrate in the electrolyte need to be
agitated only a little or even not at all, in order to achieve the
desired deposition results, so that additional devices for
agitation of the electrolyte can be omitted. In addition, because
of the advantageous use of the aromatic nonionic wetting agent,
electrolyte residues drain from the plated substrate better when it
is removed from the electrolyte, which leads to reduced entrainment
losses and thus to lower process costs.
[0014] The addition of 2-40 g/L of one or more aromatic nonionic
wetting agents is especially advantageous, with a-napththol
ethoxylate and/or nonylphenol ethoxylate are especially preferably
used.
[0015] The proposed method is therefore advantageously economical
and environmentally friendly compared to the cyanide processes.
[0016] The additional or alternative use of one or more anionic
and/or aliphatic nonionic wetting agent that is known from the
prior art is also optionally possible, provided these wetting
agents support or even enhance the advantageous effects of the
aromatic nonionic wetting agent. In this regard polyethylene
glycols and/or anionic surfactants are preferably added to the
electrolyte as anionic and/or aliphatic nonionic wetting agents.
Additional exemplary aliphatic nonionic wetting agents include
aliphatic fatty alcohol ethoxylates.
[0017] It has also been discovered that substituted dithioglycols
act advantageously as wetting agents and brighteners. Therefore,
certain embodiments of the invention include substituted
dithioglycols, such as, for example, those selected from the group
consisting of:(1) Thiobis(diethyleneglycol) represented
byH-(OCH.sub.2CH.sub.2).sub.2-S-(CH.sub.2CH.sub.2O).sub.2-H,(2)
Thiobis(hexaethylene glycol),(3) Thiobis(pentadecaglycelol)
represented
byH-(OCH.sub.2CH(OH)CH.sub.2).sub.15-S-(CH.sub.2CH(OH)CH.sub.2O).sub.15-H-
,(4) Thiobis(icosaethyleneglycol) represented
byH-(OCH.sub.2CH.sub.2).sub.20-S-(CH.sub.2CH.sub.2O).sub.20-H,(5)
Thiobis(pentacontaethyleneglycol),(6)
4,10-dioxa-7-thiatridecane-2,12-diol represented
byHO-CH(CH.sub.3)CH.sub.2-OCH.sub.2CH.sub.2-SCH.sub.2CH.sub.2-OCH.sub.2CH-
(CH.sub.3)-OH,(7) Thiodiglycerin represented
byHOCH.sub.2CH(OH)CH.sub.2-S-CH.sub.2CH(OH)CH.sub.2OH,(8)
Thiobis(triglycerin) represented
byH-(OCH.sub.2CH(OH)CH.sub.2).sub.3-S-(CH.sub.2CH(OH)CH.sub.2O)-H,(9)
2,2'-thiodibutanolbis(octaethyleneglycolpentaglycerol)ether
represented
byH-(OCH.sub.2CH(OH)CH.sub.2).sub.5-(OCH.sub.2CH.sub.2).sub.8-OC.sub.4H.s-
ub.8-SC.sub.4H.sub.8-O-(CH.sub.2CH.sub.2O).sub.8-(CH.sub.2CH(OH)CH.sub.2O)-
-H,(10) Thiobis(octaethyleneglycol)bis(2-chloroethyl)ether
represented by
Cl-CH.sub.2CH.sub.2CH.sub.2-(OCH.sub.2CH.sub.2).sub.8-S-(CH.sub.2CH.sub.2-
O).sub.8-CH.sub.2CH.sub.2CH.sub.2-Cl,(11)
Thiobis(decaethyleneglycol)bis(carboxymethyl)ether,(12)
Thiobis(dodecaethyleneglycol)bis(2-nitroethyl)ether,(13)
Thiodiglycolbis(carboxymethyl)ether represented by
HOOCCH.sub.2OCH.sub.2CH.sub.2-S-CH.sub.2CH.sub.2OCH.sub.2COOH, (14)
Dithiodiglycolbis(carboxymethyl)ether represented by
HOOCCH.sub.2OCH.sub.2CH.sub.2-S-S-CH.sub.2CH.sub.2OCH.sub.2COOH,(15)
Thiobis(dodecaethyleneglycol) represented
byH-(OCH.sub.2CH.sub.2).sub.12-S-(CH.sub.2CH.sub.2O).sub.12-H,(16)
Dithiobis(hentetracontaethyleneglycol) represented
byH-(OCH.sub.2CH.sub.2).sub.41-S-S-(CH.sub.2CH.sub.2O).sub.41-H,(17)
Dithiobis(icosaethyleneglycolpentapropyleneglycol) represented by
H-(OC.sub.3H.sub.6).sub.5-(OC.sub.2H.sub.4).sub.20-S-S-(OC.sub.2H.sub.4).-
sub.20-(OC.sub.3H.sub.6).sub.5-H,(18) Dithiobis(triglycerol)
represented
byH-(OCH.sub.2CH(OH)CH.sub.2).sub.3-S-S-(CH.sub.2CH(OH)CH.sub.2O).sub.3-H-
,(19) Dithiobis(decaglycelol),(20) 3,6-Dithiaoctane-1,8-diol
represented
byHOCH.sub.2CH.sub.2S-CH.sub.2CH.sub.2-SCH.sub.2CH.sub.2OH,(21)
1,3-Propanedithiolbis(decaethyleneglycol)thioether represented by
H-(OC.sub.2H.sub.4).sub.10-S-C.sub.3H.sub.6-S-(OC.sub.2H.sub.4).sub.10-H,
(22) 1,4-Buthanedithiolbis(pentadecaglycerol)thioetherrepresented
by
H-(OCH.sub.2CH(OH)CH.sub.2).sub.15-S-C.sub.4H.sub.8-S-(CH.sub.2CH(OH)CH.s-
ub.2O).sub.15-H,(23)
1,3-Dithioglycerolbis(pentaethyleneglycol)thioetherrepresented by
H-(OCH.sub.2CH.sub.2).sub.5-SCH.sub.2CH(OH)CH.sub.2S-(CH.sub.2CH.sub.2O).-
sub.5-H, (24)
1,2-Ethanedithiolbis(penta(1-ethyl)ethyleneglycol)thioether
represented
byH-(OCH(C.sub.2H.sub.5)CH.sub.2).sub.5-SC.sub.2H.sub.4S-(CH.sub.2CH(C.su-
b.2H.sub.5)O).sub.5-H,(25)
1,3-Dithioglycerolbis(di(1-ethyl)ethyleneglycol)thioetherrepresented
byH-(OCH(CH.sub.3)CH.sub.2).sub.2-SCH.sub.2CH(OH)CH.sub.2S-(CH.sub.2CH(CH-
.sub.3)O).sub.2-H,(26)
2-Mercaptoethylsulfidebis(hexatriacontaethylene-glycol) represented
by
H-(OC.sub.2H.sub.4).sub.18-SC.sub.2H.sub.4-SC.sub.2H.sub.4-S-(C.sub.2H.su-
b.4O).sub.18-H, (27)
2-Mercaptoethylsulfidebis(icosaethyleneglycol)di-methylether
represented
byCH.sub.3-(OC.sub.2H.sub.4).sub.10-SC.sub.2H.sub.4-SC.sub.2H.sub.4-S-(C.-
sub.2H.sub.4O).sub.10-CH.sub.3, (28)
2-Mercaptoethyletherbis(diethyleneglycol) represented by
H-(OC.sub.2H.sub.4).sub.2-S-CH.sub.2CH.sub.2OCH.sub.2CH.sub.2-S-(C.sub.2H-
.sub.4O).sub.2-H,(29) Thiodiglyceroltetra(decaethyleneglycol)ether
representedby the above formula (6),(30)
Diethyleneglycolmonomethylthioether represented
byCH.sub.3-S-(CH.sub.2CH.sub.2O).sub.2-H,(31)
Decaglycerolmono(6-methylthiohexyl)thioether represented by
CH.sub.3-S-C.sub.6H.sub.12-S-(CH.sub.2CH(OH)CH.sub.2O).sub.10-H,
(32)
2-Mercaptoethylsulfide-.omega.-{(2-bromoethyl)icosaethyleneglycol}thioeth-
er-.omega.'-{(2-bromoethyl)hectaethyleneglycol}thioether
represented
byBrCH.sub.2CH.sub.2-(OCH.sub.2CH.sub.2).sub.20-(S-CH.sub.2CH.sub.2).sub.-
3-(OCH.sub.2CH.sub.2).sub.100-OCH.sub.2CH.sub.2Br,(33)
1,4-Butanediol-.omega.-{(2-benzyloxy-1-methyl)ethyl}thioether-.omega.'-(d-
ecapropyleneglycoloctacontaethyleneglycol)thioether represented
byPhCH.sub.2OCH.sub.2CH(CH.sub.3)-S-C.sub.4H.sub.8-S-(CH.sub.2CH.sub.2O).-
sub.80-(CH.sub.2CH(CH.sub.3)O).sub.10-H, (34)
Dithiobis(icosaethyleneglycol)bis(2-methyl-thioethyl)ether
represented
byCH.sub.3-S-CH.sub.2CH.sub.2-(OCH.sub.2CH.sub.2).sub.20-S-S-(CH.sub.2CH.-
sub.2O).sub.20-CH.sub.2CH.sub.2-S-CH.sub.3,(35)
1,2-Ethanediol-.omega.-(4-methoxybenzyl)thioether-.omega.'-(pentacontaeth-
yleneglycol) thioether represented
byCH.sub.3O-Ph-CH.sub.2S-CH.sub.2CH.sub.2-(CH.sub.2CH.sub.2O).sub.50-H,
(36) Triacontaethyleneglycolmono(4-cyanobenzyl)thioether
represented by NC-Ph-CH.sub.2-S-(CH.sub.2CH.sub.2O).sub.30-H, (37)
Thiobis(pentadecaethyleneglycol)bisallylether represented by
CH.sub.2=CHCH.sub.2-(OCH.sub.2CH.sub.2).sub.15-S-(CH.sub.2CH.sub.2O).sub.-
15-CH.sub.2CH=CH.sub.2, (38)
Tricosaethyleneglycolmono(4-formylphenetyl)thioetherrepresented by
OHC-Ph-CH.sub.2CH.sub.2-S-(CH.sub.2CH.sub.2O).sub.23-H, (39)
Pentadecaethyleneglycolmono{(acetylmethyl)thioethyl}thioether
represented by
CH.sub.3COCH.sub.2-S-CH.sub.2CH.sub.2-S-(CH.sub.2CH.sub.2O).sub.15-H,(-
40)
1,2-Ethanediol-.omega.-(glycidyl)thioether-.omega.'-icosaethyleneglyco-
lthioether represented by ##STR1## 41)
Octadecaethyleneglycolbis(2-methylthioethyl)ether represented by
CH.sub.3-S-CH.sub.2CH.sub.2CO-(CH.sub.2CH.sub.2O).sub.18-CH.sub.2CH.sub.2-
S-CH.sub.3, (42)
Hexadecaethyleneglycolmono(2-methylthioethyl)thioetherrepresented
by CH.sub.3-S-CH.sub.2CH.sub.2-S-(CH.sub.2CH.sub.2O).sub.16-H, (43)
Icosaethyleneglycolmonomethylthioether represented
byCH.sub.3-S-(CH.sub.2CH.sub.2O).sub.20-H, (44)
Undecaethyleneglycoldi(n-propyl)thioether represented
byC.sub.3H.sub.7-S-(CH.sub.2CH.sub.2O).sub.10-CH.sub.2CH.sub.2S-C.sub.3H.-
sub.7, (45) Dodecaethyleneglycolbis(2-hydroxyethyl)thioether
represented by
HOCH.sub.2CH.sub.2-S-(CH.sub.2CH.sub.2O).sub.11-CH.sub.2CH.sub.2-S-CH.-
sub.2CH.sub.2OH, (46) Undecaethyleneglycoldimethylthioether, (47)
Pentatriacontaethyleneglycolmono(2-n-butyldithioethyl)dithioether
represented
byC.sub.4H.sub.9-S-S-CH.sub.2CH.sub.2-S-S-(CH.sub.2CH.sub.2O).sub.35-H,
(48) 4,8,12-trithiapentadecane-1,2,6,10,14,15-hexaolrepresented
byHOCH.sub.2CH(OH)CH.sub.2-S-CH.sub.2CH(OH)CH.sub.2-S-CH.sub.2CH(OH)CH.su-
b.2-S-CH.sub.2CH(OH)CH.sub.2OH,(49)
Icosaglycerolmono(2-ethylthioethyl)thioether represented by
C.sub.2H.sub.5-S-CH.sub.2CH.sub.2-S-(CH.sub.2CH(OH)CH.sub.2O).sub.20-H,
(50) Triacontaethyleneglycolmono(2-methylthioethyl)thioether
represented by
CH.sub.3-S-CH.sub.2CH.sub.2-S-(C.sub.2H.sub.4O).sub.30-H, (51)
Dithiobis(icosaethyleneglycol)dibenzylether represented by
Ph-CH.sub.2-(OC.sub.2H.sub.4).sub.20-S-S-(C.sub.2H.sub.4O).sub.20-CH.sub.-
2-Ph, (52) Tridecaethyleneglycolmonomethylthioether represented by
CH.sub.3-S-(CH.sub.2CH.sub.2O).sub.10-H, (53)
Hexadecaethyleneglycol dimethylthioether represented by
CH.sub.3-S-(CH.sub.2CH.sub.2O).sub.15-CH.sub.2CH.sub.2-S-CH.sub.3,
(54) 1,2-Ethanedithiolbis(icosaethyleneglycol)thioether represented
by
H-(OCH.sub.2CH.sub.2).sub.20-S-CH.sub.2CH.sub.2-S-(CH.sub.2CH.sub.2O).sub-
.20-H, (55) Dithiobis(pentadecaethyleneglycol) represented
byH-(OCH.sub.2CH.sub.2).sub.15-S-S-(CH.sub.2CH.sub.2O).sub.15-H,
and (56) 3,3'-thiodipropanol represented
byHO-CH.sub.2CH.sub.2CH.sub.2-S-CH.sub.2CH.sub.2CH.sub.2-OH. In the
above-listed structural formulae, Ph represents a phenyl group.
[0018] As already mentioned above, the method in accordance with
the invention is characterized in particular by the special
composition of the electrolyte. It contains essentially tin and
copper ions, an alkylsulfonic acid and an aromatic nonionic wetting
agent. In addition, stabilizers and/or complexing agents, anionic
and/or nonionic, aliphatic and/or substituted dithioglycol wetting
agents, oxidation inhibitors, brighteners, and other metal salts
can optionally be contained in the electrolyte.
[0019] The metals that are primarily added to the electrolyte for
deposition of bronzes in accordance with the invention tin and
copper can first and foremost be in the form of salts of
alkylsulfonic acids, preferably as methanesulfonates, or as salts
of mineral acids, preferably as sulfates. Tin methanesulfonate is
especially preferably used as tin salt in the electrolyte
preferably in an amount of 5-195 g/L of electrolyte, preferably
11-175 g/L of electrolyte. This corresponds to a use of 2-75 g/L,
preferably 4-57 g/L divalent tin ions. Copper methanesulfonate is
especially preferably used in the electrolyte as the copper salt,
which is advantageously added to the electrolyte in an amount of
8-280 g/L of electrolyte, preferably 16-260 g/L of electrolyte.
This corresponds to the use of 2-70 g/L, preferably 4-65 g/L
divalent copper ions.
[0020] Since the deposition is clearly higher in an acid
environment, an acid, preferably a mineral and/or an alkylsulfonic
acid, is added to the electrolyte in amounts of 140-382 g/L of
electrolyte, preferably 175-245 g/L of electrolyte. The use of
methanesulfonic acid turned out to be especially advantageous,
since for one thing this produces advantageous solubility of metal
salts and for another, because of its acid strength, it produces or
facilitates the adjustment of the pH needed for the process. In
addition, methanesulfonic acid has the advantageous property of
contributing considerably to the stability of the bath.
[0021] In accordance with an additional characteristic of the
invention at least one additional metal and/or chloride is added to
the electrolyte. Advantageously, the metals are in the form of
their soluble salts. In particular, the addition of zinc and/or
bismuth has a considerable effect on the properties of the
deposited coatings. The metals zinc and/or bismuth added to the
electrolyte can namely be in the form of salts of alkylsulfonic
acids, preferably as methanesulfonates or as salts of mineral
acids, preferably as sulfates. Zinc sulfate is especially
preferably uses in the electrolytes as zinc salt, and is
advantageously added in an amount of 0-25 g/L of electrolyte,
preferably 15-20 g/L of electrolyte. Bismuth methane sulfate is
especially preferably used in the electrolyte as bismuth salt and
is advantageously added to the electrolyte in an amount of 0-5 g/L
of electrolyte, preferably 0.05-0.2 g/L of electrolyte.
[0022] In addition, various additives, for example stabilizers
and/or complexing agents, oxidation inhibitors and brighteners,
that are usually used in acid electrolytes for deposition of tin
alloys can be added to the electrolyte.
[0023] In particular, the use of suitable compounds for stabilizing
the electrolyte is an important condition for rapid as well as
qualitative high grade deposition of bronzes. Gluconates are
advantageously added to the electrolyte and stabilizers and/or
complexing agents. Here in the method in accordance with the
invention the preferred use of sodium gluconate turned out to be
especially advantageous. The concentration of the stabilizers
and/or complexing agents is 0-50 g/L of electrolyte, preferably
20-30 g/L of electrolyte. Compounds from the class of the
dihydroxybenzenes, for example mono- or polyhydroxyphenyl compounds
like pyrocatechol or phenolsulfonic acid are preferably used as
oxidation inhibitors. The concentration of oxidation inhibitors is
0-5 g/L of electrolyte. Advantageously, the electrolyte contains
hydroquinone as oxidation inhibitor.
[0024] The conduct of the method in accordance with the invention
enables the deposition of bronzes onto various substrates. For
example, all of the usual methods for making electronic components
can be used. In the same way especially hard and wear-resistant
bronze coatings can be deposited on materials like bearings, etc.,
to the method in accordance with the invention. The method in
accordance with the invention is advantageously also used in the
fields of decorative coating of, for example, fixtures and jewelry,
etc., where the deposition of multi-component alloys that contain
tin, copper, zinc and bismuth is particularly advantageous in these
areas.
[0025] A really special advantage is that the so-called "true"
bronzes that have a copper content >60% can be deposited with
the method in accordance with the invention, where the copper
content can be up to 95 wt% in each according to the desired
properties. In addition, the ratio of the amount of copper to the
amount of tin in the electrolyte has a considerable effect of
properties like hardness and color of the bronze coatings. For
instance, at a tin/copper ratio of 40/60 silver-colored coatings,
the so-called white bronzes, which are relatively soft, are
deposited. At a tin/copper ratio of 20/80 yellow gold colored
coatings result, the so-called yellow bronzes, and at a tin/copper
ratio of 10/90 red gold colored coatings are formed, the so-called
red bronzes.
[0026] Moreover, the deposition of high-tin white bronzes with a
copper content = 10% is also possible.
[0027] In each case according to the desired appearance of the
bronze coatings additives such as brighteners are added to the
electrolyte, in addition to it having a varying copper content.
Advantageously, the electrolyte contains brighteners from the class
of the aromatic carbonyl compounds and/or a,a-unsaturated carbonyl
compounds. The concentration of brighteners is 0-5 g/L of
electrolyte.
[0028] Some preferred embodiments are presented below for
illustration of the invention in more detail, but the invention is
not limited to these embodiments.
Electrolyte composition:
[0029] The base electrolyte of the highly acid electrolyte in
accordance with the invention contains essentially (per liter of
electrolyte) 2-75 g divalent tin, 2-70 g divalent copper, 2-40 g of
an aromatic nonionic wetting agent, and 140-382 g of a mineral
and/or alkylsulfonic acid.
[0030] Optionally, other components can be added to the electrolyte
(per liter of electrolyte): 0-10 g of an anionic and/or aliphatic
nonionic wetting agent, 0-50 g of a stabilizer and/or complexing
agent, 0-5 g of an oxidation inhibitor, 0-5 g of a brightener 0-5
trivalent bismuth 0-25 g divalent zinc.
[0031] In order to achieve a specific color of the deposited bronze
coatings the electrolyte is prepared by varying the individual
components, as given below as a matter of example. Additional
information about the corresponding process conditions as well as
other properties of the individual coatings can be seen in Table
1.
[0032] Example 1 (red bronze) 4 g/L Sn.sup.2+ 18 g/L Cu.sup.2+ 286
g/L methanesulfonic acid 3 g/L aromatic nonionic wetting agent 0.4
g/l aliphatic nonionic wetting agent 2 g/L oxidation inhibitor 20
mg/L complexing agent
[0033] Example 2a (yellow bronze) 4 g/L Sn.sup.2+ 18 g/L Cu.sup.2+
240 g/L methanesulfonic acid 32.2 g/L aromatic nonionic wetting
agent 2 g/L oxidation inhibitor 25 mg/L stabilizer/complexing
agent
[0034] Example 2b (yellow bronze) 4 g/L Sn.sup.2+ 18 g/L Cu.sup.2+
286 g/L methanesulfonic acid 32.2 g/L aromatic nonionic wetting
agent 6 mg/L brightener 2 g/L oxidation inhibitor 50 mg/L
stabilizer/complexing agent
[0035] Example 3 (white bronze) 5 g/L Sn.sup.2+ 10 g/L Cu.sup.2+
240 g/L methanesulfonic acid 32.2 g/L aromatic nonionic wetting
agent 6 mg/L brightener 2 g/L oxidation inhibitor 25 mg/L
stabilizer/complexing agent
[0036] Example 4 (matte white bronze) 18 g/L Sn.sup.2+ 2 g/L
Cu.sup.2+ 258 g/L methanesulfonic acid 9 g/L aromatic nonionic
wetting agent
[0037] To improve the hardness and/or ductility of the deposited
bronze coatings the contents of zinc and/or bismuth indicated below
as examples are added to the electrolyte. Additional data on the
corresponding process conditions and other properties of the
individual coatings can be seen in Table 1.
[0038] Example 5 (high ductility) 4 g/L Sn.sup.2+ 18 g/L Cu.sup.2+
238 g/L methanesulfonic acid 32.2 g/L aromatic nonionic wetting
agent 3 mg/L brightener 2 g/L oxidation inhibitor 25 mg/L
stabilizer/complexing agent 20 g/L ZnSO.sub.4
[0039] Example 6 (hardness) 4 g/L Sn.sup.2+ 18 g/L Cu.sup.2+ 238
g/L methanesulfonic acid 32.2 g/L aromatic nonionic wetting agent 2
g/L oxidation inhibitor 25 mg/L stabilizer/complexing agent 0.1 g/L
Bi.sup.3+
[0040] Example 7 (yellow bronze) 14.5 g/L Sn.sup.2+ 65.5 g/L
Cu.sup.2+ 382 g/L methanesulfonic acid 32.2 g/L aromatic nonionic
wetting agent 4 g/L oxidation inhibitor 25 mg/L
stabilizer/complexing agent 20 g/L ZnSO.sub.4
[0041] Example 8 (yellow bronze) 2 g/L Sn.sup.2+ 8 g/L Cu.sup.2+
400 g/L methanesulfonic acid 2.5 g/L aromatic nonionic wetting
agent 1 g/L fatty alcohol ethoxylate 4 g/L oxidation inhibitor
[0042] Example 9 (white bronze) 4 g/L Sn.sup.2+ 8 g/L Cu.sup.2+ 400
g/L methanesulfonic acid 1 g/L aromatic nonionic wetting agent 40
mg/L substituted dithioglycol 4 g/L oxidation inhibitor
[0043] With these exemplary electrolyte compositions coatings with
specific properties were deposited under the process conditions
listed in the following table.Table TABLE-US-00001 Coating/Amounts
in wt % Properties of coating Example No. Sn Cu Zn Bi Hardness
Ductility Gloss Color 1 10 90 180 HV.sub.50 15 ++ Yes Red 2 20 80
283 HV.sub.50 .+-. Yes Yellow 2b 20 80 317 HV.sub.50 .+-. Yes
Yellow 3 40 60 360 HV.sub.50 .+-. Yes White 4 90 10 No White 5 20
80 <1 +++ Yes Yellow 6 20 80 <1 345 HV.sub.50 Yes Yellow 7 20
80 <1 ++ Yes Yellow
[0044]
[0045] When introducing elements of the present invention or the
preferred embodiment(s) thereof, the articles "a," "an," "the," and
"said" are intended to mean that there are one or more of the
elements. The terms "comprising," "including," and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[0046] In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous
results attained.
[0047] As various changes could be made in the above methods and
products without departing from the scope of the invention, it is
intended that all matter contained in the above description and
shown in any accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
* * * * *