KR101712960B1 - Cyanide-free electroplating baths for white bronze based on copper (i) ions - Google Patents

Abstract

Copper alloy electroplating baths contain at least one copper (I) ion source and at least one tin ion to electroplating a mirror-polished white bronze copper / tin alloy. In addition, the copper alloy may include one or more silver ion sources to electroplating an alloy of copper / tin / silver of mirror bright white bronze. The copper alloy electroplating bath is free of cyanide.

Description

CYANIDE-FREE ELECTROPLATING BATHS FOR WHITE BRONZE BASED ON COPPER (I) IONS FOR COPPER ION (I)

The present invention relates to cyanide-free electroplating baths for white bronze based on copper (I) ions. More specifically, the present invention relates to a cyanide-free electroplating bath for white bronze based on copper (I) ions electroplating stable, bright white bronze deposits.

White bronze is a substitute for nickel and is typically used in the decorative and sanitary industry. Generally, the bronze is 40 wt% to 70 wt% copper and has the balance tin or tin and silver or tin and zinc. It is rigid enough to provide adequate wear resistance and corrosion resistance, which can replace nickel in both decorative and sanitary functions. At present, most industrial white bronze is not only toxic due to its cyanide content, but also has a relatively low plating rate of from 0.1 ASD to about 2 ASD with a low current efficiency ranging from 50% to 80%.

US Patent No. 7,780,839 to Egli et al. Relates to cyanide-free white bronze that can be used as an alternative to conventional cyanide-containing white bronze electroplating baths. Although the plating rate of this electrolyte has significantly improved for many conventional white bronze electroplating baths, the white bronze deposits are a little fragile and may not pass the abrasion test. It may also be difficult to coat a finishing overlay, such as gold, chromium (III) or (VI), palladium or silver, on the white bronze. In the top coating of articles for decorative and hygienic applications, the general process is to degrease the article using conventional degreasing agents, rinse with water, then thick copper plating for leveling purposes, followed by a cyanide containing plating bath, (III) or (VI), palladium or silver finish on a white bronze surface. When a cyanide-free white bronze electroplating bath is used as in U.S. Patent No. 7,780,839, a separate step is typically required prior to plating the finish layer. An organic film of unknown composition can be formed on the white bronze after electroplating, which reduces the surface appearance of the white bronze. The ultrasonic cleaning or cathodic degreasing step is then included in the process to remove the film prior to plating the finish layer. This extra step reduces the efficiency and increases the cost of the entire process because the ultrasonic equipment must be installed or a separate tank with a current supply in case of cathode degreasing is needed. Thus, there is still a need for improved white bronze electroplating and processing.

SUMMARY OF THE INVENTION

Wherein the electroplating bath comprises at least one source of copper (I) ions, at least one source of tin alloying ions, optionally at least one source of silver ion silver ions, at least one compound having the formula (I)

X-S-Y (I)

Wherein X and Y may be the same or different and are a substituted or unsubstituted phenoxy group, HO-R- or -R'S-R "-OH, and R, R 'and R" And is a linear or branched alkylene radical having from 1 to 20 carbon atoms; And at least one tetrazole, wherein the molar ratio of the at least one tetrazole to the copper (I) ion in the electroplating bath is at least 1, and wherein the at least one tetra sol of the at least one compound of formula (I) Sol molar ratio is 0.05 to 4, and the electroplating bath is cyanide-free.

The electroplating process may comprise depositing a substrate, at least one source of copper (I) ions, at least one source of tin alloy ions, optionally at least one source of silver ion silver ions, at least one compound having the formula (I)

 X-S-Y (I)

Wherein X and Y may be the same or different and are a substituted or unsubstituted phenoxy group, HO-R- or -R'S-R "-OH, and R, R 'and R" And is a linear or branched alkylene radical having from 1 to 20 carbon atoms; And at least one tetrazole, wherein the molar ratio of said at least one tetrazole to said copper (I) ion in said electroplating bath is at least 1, and wherein the molar ratio of said at least one tetrazole to said copper (I) Wherein the molar ratio of the at least one tetrazole to the at least one compound is 0.05 to 4 and the electroplating bath is cyanide-free; And electroplating a copper / tin alloy or a copper / tin / silver alloy onto the substrate.

Cyanide-Free Copper Alloys Electroplating deposits bright, white bronze copper / tin alloys or copper / tin / silver alloys. Copper alloy electroplating deposits copper / tin alloys and copper / tin / silver alloys with high current efficiency and high plating rates in contrast to many conventional copper alloy plating baths that are stable over time and electroplating white bronze. The copper / tin alloy and the copper / tin / silver alloy electroplated from the plating bath have good ductility, thermal stability and abrasion resistance. The copper / alloy may be directly plated with gold, chromium (III) or (VI), palladium and silver finish layers without any post-processing steps of many conventional processes, such as ultrasonic cleaning or negative electrode degreasing. Thus, the cyanide-free copper alloy electroplating bath enables a more efficient process than many conventional cyanide-free white bronze processes and can be used for nickel replacement.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of% current efficiency vs. plating bath life of a cyanide-free copper / tin / silver alloy electroplating bath.
FIG. 2 is a photograph of a chromium layer on an electroplated white bronze deposit from a cyanide-free copper (I) containing electroplating bath at room temperature for one month.
3 is a photograph of a chromium layer on a cyanide-free white bronze deposit electroplated from a copper (II) containing electroplating bath at room temperature for one month.

As used throughout this specification, the following abbreviations have the following meanings, unless the context clearly indicates otherwise: ° C = degrees Celsius; g = gram; cm = centimeter; mL = milliliters; L = liters; mg = milligram; ppm = million fractions = mg / L; DI = deionized; Mu m = micron; mol = mol; wt% = weight percent; A = ampere; A / dm ² and ASD = amps per square decimeter; Ah = amperage time; % CE = percent current efficiency; rpm = number of revolutions per minute; IEC = International Electrochemical Committee; XRF = X-ray fluorescence; And ASTM = American Standard Test Method. An electroplating potential is provided for the hydrogen reference electrode. With regard to the electroplating process, the terms "deposition", "coating", "electroplating" and "plating" are used interchangeably throughout this specification. "Halide" refers to fluoride, chloride, bromide, and iodide. All percentages are by weight, unless otherwise noted. All numerical ranges are inclusive and arbitrary in any order except that the logical parts are interpreted as summing up to 100% of such numerical ranges.

Copper (I), silver, tin, and copper (I) and tin alloy electroplating baths are substantially free of cyanide. The cyanide is largely avoided by not using any silver or tin salts or other compounds in the plating bath containing CN ^- anions. Copper (I), silver, tin and copper (I) and tin alloy electroplating baths are also substantially free of copper (II) ions so that copper alloy electroplating baths can coat bright white bronze deposits.

Sources of copper (I) ions include, but are not limited to, cuprous salts such as cuprous oxide, cuprous chloride, cuprous bromide, cuprous iodide and cuprous iodide, such as cuprous chloride cuprate. Copper (I) salts are generally commercially available or can be prepared by methods described in the literature. When copper (I) oxide is used, alkane or aryl sulfonic acid or a mixture thereof is preferably included in the plating bath. One or more copper (I) salts are included in the plating bath in an amount sufficient to enable the amount of copper (I) ions to range from 0.5 g / L to 150 g / L, preferably from 10 g / L to 50 g / L .

Sources of tin ions include, but are not limited to, salts such as tin halides, tin sulphates, tin alkane sulphonates, tin alkanol sulphonates, and acids. When tin halide is used, it is common that the halide is chloride. The tin compound is preferably tin sulfate, tin chloride or tin alkane sulphonate, and more preferably tin sulfate or tin methane sulphonate. Tin compounds are generally commercially available or can be prepared by methods known in the literature. Preferably the tin salts are readily water-soluble. The amount of tin salt used in the plating bath depends on the desired composition of the alloy being deposited and the operating conditions. A sufficient amount of tin salt is included in the plating bath to provide tin ions that can range from 1 g / L to 100 g / L, preferably from 5 g / L to 50 g / L.

The source of silver ions includes, but is not limited to, silver halide, silver gluconate, silver citrate, silver lactate, silver nitrate, silver sulfate, silver alkanesulfonate and silver alkanol sulfonate. When a halide is used, it is preferred that the halide is chloride. Preferably, the silver salt is silver sulfate, silver alkane sulfonate or a mixture thereof. Silver salts are generally commercially available or can be prepared by methods described in the literature. Preferably the silver salt is readily water-soluble. The amount of at least one silver salt used in the plating bath depends, for example, on the desired alloy composition to be deposited and the operating conditions. A sufficient amount of silver salt is included in the plating bath to provide silver ions that can range from 0.01 g / L to 100 g / L, preferably from 0.5 g / L to 50 g / L.

The copper (I) alloy electroplating bath comprises at least one sulfur compound having the formula (I)

X-S-Y (I)

X and Y may be a substituted or unsubstituted phenol group, HO-R- or -R'-SR "-OH, wherein R, R 'and R" are the same or different and are selected from the group consisting of 1 to 20 carbon atoms Lt; / RTI > alkylene radical. Substituents on the phenol include, but are not limited to, linear or branched (C ₁ -C ₅ ) alkyl. These compounds can function as complexing agents for copper (I) ions.

Examples of such compounds in which X and Y are the same are 4,4'-thiodiphenol, 4,4'-thiobis (2-methyl-6-tert-butylphenol) and thiodiethanol.

When X and Y are different, the compound preferably has the general formula (II)

HO-R-S-R'-S-R "-OH (II)

Wherein R, R 'and R "are the same or different and are a linear or branched alkylene radical having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably R and R" Has 2 to 10 carbon atoms, and R 'has 2 carbon atoms. Such compounds are known as dihydroxybis-sulfide compounds. Preferably, the dihydroxybis-sulfide compound is included in the alloy plating bath for the phenol-containing compound.

Examples of such dihydroxybis-sulfide compounds include 2,4-dithia-1,5-pentanediol, 2,5-dithia-1,6-hexanediol, 2,6- Heptanediol, 2,7-dithia-1,8-octanediol, 2,8-dithia-1,9-nonanediol, 2,9-dithia-1,10- decanediol, Thia-1,12-dodecanediol, 5,8-dithia-1,12-dodecanediol, 2,15-dithia-1,16-hexadecanediol, 2,21- -Deoic acid diol, 3,5-dithia-1,7-heptanediol, 3,6-dithia-1,8-octanediol, 3,8-dithia-1,10-decanediol, Dithia-1,8-dodecanediol, 3,13-dithia-1,15-pentadecanediol, 3,18-dithia-1,20-eicosanediol, 4,6- , 9-nonanediol, 4,7-dithia-1,10-decanediol, 4,11-dithia-1,14-tetradecanediol, 4,15-dithia-1,18-octadecanediol, Dithia-1,22-toeicosanediol, 5,7-dithia-1,11-undecanediol, 5,9-dithia-1,13-tridecanediol, 5,13-di Thia-1,17-heptadecanediol, 5,17-dithia-1,21-ylicoic acid diol and 1,8-dimethyl- -Dithia-1,8-octanediol.

The copper (I) alloy plating bath also contains at least one tetrazole as a complexing agent for copper (I) ions. Such tetrazoles are heterocyclic nitrogen compounds having a five-membered ring and at least one sulfur substituent on the ring. Without being bound by theory, tetrazoles with compounds of formulas (I) and (II) inhibit the oxidation of copper (I) ions to copper (II) ions and stabilize the plating bath. The inhibition of the oxidation of copper (I) ions to copper (II) ions assists in the formation of copper / tin / silver or copper / tin alloys. The tetrazole has a molar ratio of tetrazole to copper (I) ion in the plating bath of at least 1, preferably> 1, more preferably> 1 to 10, even more preferably> 1 to 6 and most preferably 1.1 To 4 in the plating bath. Generally, the amount of tetrazole contained in the plating bath may range from 0.5 g / L to 500 g / L.

 The compounds of formulas (I) and (II) are included in the plating bath such that the molar ratio of at least one tetrazole to the compound of formula (I) or (II) is 0.05-4, preferably 0.1-3.

Preferably the tetrazole is a mercaptotetrazole compound having the formula (III): < EMI ID =

Wherein, M is hydrogen, NH _4, sodium or potassium and R ₁ is a substituted or unsubstituted, linear or branched (C ₂ -C ₂₀₎ alkyl, substituted or unsubstituted (C ₆ -C ₁₀₎ aryl, preferably substituted or unsubstituted, linear or branched (C ₂ -C ₁₀₎ alkyl and substituted or unsubstituted (C ₆₎ aryl, more preferably substituted or unsubstituted, linear or branched (C ₂ -C ₁₀₎ alkyl. Substituents include, but are not limited to, alkoxy, phenoxy, halogen, nitro, amino, substituted amino, sulfo, sulfamyl, substituted sulfamyl, sulfonylphenyl, sulfonyl-alkyl, fluorosulfonyl, sulfamidophenyl, Carboxy, carboxylate, ureidocarbamyl, carbamyl-phenyl, carbamylalkyl, carbonylalkyl, and carbonylphenyl. Preferred substituents include amino and substituted amino groups. Examples of the mercaptotetrazole include 1- (2-diethylaminoethyl) -5-mercapto-1,2,3,4-tetrazole, 1- (3-ureidophenyl) -5-mercaptotetrazole , 1- (4-acetamidophenyl) -5-mercapto-tetrazole and 1- (4-carboxyphenyl) ) -5-mercaptotetrazole.

The combination of one or more tetrazoles with the compounds of formula (I) or (II) provides stability to alloy compositions that are stable over the applicable current density range as well as alloy plating baths during storage or during electroplating, / Tin / silver or copper / tin alloy can be deposited as an alternative to nickel in decorative or sanitary articles.

Any water-soluble acid may be used so long as it does not adversely affect the plating bath. Suitable acids include, but are not limited to, arylsulfonic acids, alkanesulfonic acids such as methanesulfonic acid, ethanesulfonic acid and propanesulfonic acid, arylsulfonic acids such as phenylsulfonic acid and tolylsulfonic acid, and inorganic acids such as sulfuric acid, sulfamic acid, Hydrobromic acid and fluoroboric acid. Typically, the acid is an alkanesulfonic acid and an arylsulfonic acid. Mixtures of acids may be used, but it is common for a single acid to be used. Acids are generally commercially available or can be prepared by methods known in the literature.

The preferred alloy composition and operating conditions, while the amount of acid in the plating composition is from 0.01 to 500 g / L or Such as from 10 to 400 g / L. If the silver and tin ions are from metal halides, the use of the corresponding acid may be preferred. For example, where more than one tin chloride or silver chloride is used, the use of hydrochloric acid as the acid component may be preferred. Mixtures of acids may also be used.

Optionally, one or more inhibitors may be included in the plating bath. Typically it is used in an amount of from 0.5 to 15 g / L or such as from 1 to 10 g / L. Such inhibitors include, but are not limited to, alkanolamines, polyethyleneimines and alkoxylated aromatic alcohols. Suitable alkanolamines include, but are not limited to, substituted or unsubstituted, methoxylated, ethoxylated, and propoxylated amines such as tetra (2-hydroxypropyl) ethylenediamine, 2 (2-hydroxyethyl) -ethylenediamine, 2- (2-aminoethylamine) -ethanol, and combinations thereof. .

Suitable polyethyleneimines include, but are not limited to, substituted or unsubstituted linear or branched chain polyethyleneimines having a molecular weight of 800-750,000, or mixtures thereof. Suitable substituents include, for example, carboxyalkyl, such as carboxymethyl, carboxyethyl.

Useful alkoxylated aromatic alcohols include, but are not limited to, ethoxylated bisphenols, ethoxylated phenols, ethoxylated beta-naphthols, and ethoxylated nonylphenols.

Optionally, at least one reducing agent may be added to the plating bath to assist the tin to remain soluble and bivalent. Suitable reducing agents include, but are not limited to, hydroquinone, hydroquinone sulfonic acid, potassium salts, and hydroxylated aromatic compounds such as resorcinol and catechol. When used in the compositions, such reducing agents are present in an amount of from 0.01 to 20 g / L or such as from 0.1 to 5 g / L.

For applications requiring good wetting capabilities, one or more conventional surfactants may be included in the plating bath. Surfactants include ethylene oxide and / or propylene oxide derivatives of aliphatic alcohols containing at least one alkyl group, and ethylene oxide and / or propylene oxide derivatives of aromatic alcohols. Aliphatic alcohols may be saturated or unsaturated. These aliphatic and aromatic alcohols may be further substituted, for example, with a sulfate or sulfonate group. Surfactants may be included in customary amounts. Generally, the surfactant may be included in an amount of from 0.1 g / L to 50 g / L.

Any other compound may be added to the plating bath to provide additional grain refinement. Such compounds include, but are not limited to, alkoxylates such as polyethoxylated amine JEFFAMINE T-403 or TRITON RW, or sulfated alkyl ethoxylates such as TRITON QS-15, and gelatin or gelatin derivatives . Alkoxylated oxides can also be included. Conventional amounts of such grain refiners may be used. Typically this is included in the plating bath in an amount of from 0.5 g / l to 20 g / l.

Other crystal grain refining agents include, but are not limited to, the pentanoleol compounds such as 1,10-phenanthroline monohydrate, bismuth salts such as bismuth nitrate, bismuth acetate, bismuth tartrate and bismuth alkane sulphonate. Indium salts such as indium chloride, indium sulfate and indium alkanesulfonate. Antimony salts such as antimony lactate, antimony potassium tartrate. Selenium and tellurium can be added as the dioxide. Iron salts such as ferric bromide and anhydrous ferric chloride. Cobalt salts such as cobalt nitrate, bromide and cobalt chloride. Zinc salts such as zinc lactate and zinc nitrate. Chromium salts such as chromium chloride and chromium formate. The crystal grain refiner is contained in a usual amount. Generally, such grain refiners are included in an amount of 5 ppm to 1000 ppm.

Electroplating typically involves adding to the vessel at least one acid, at least one compound of formula (I) and at least one tetrazole followed by at least one solution soluble copper (I), silver and tin compounds, ≪ / RTI > and balance water. Preferably, the compound of formula (II) and the tetrazole are added to the vessel and then copper (I) compound and acid are added before the silver and tin compound. When an aqueous plating bath is prepared, undesirable materials can be removed, for example by filtration, and then water is typically added to adjust the final volume of the plating bath. The plating bath can be agitated by any known means, such as stirring, pumping, or recirculating, for increased plating rates. The plating bath is acidic with a pH of less than 7, preferably less than 3.

The current density used to coat the copper alloy depends on the particular plating method. In general, the current density is an ASD of 0.01 or more, preferably 0.1 ASD to 10 ASD, more preferably 1 ASD to 6 ASD.

Copper / tin / silver and copper / tin alloys may be electroplated at room temperature to 60 占 폚, preferably 30 占 to 50 占 폚. More preferably, the electroplating is performed at a temperature of 30 캜 to 40 캜.

The plating bath can be used to deposit copper / tin / silver and copper / tin alloys of various compositions. Typically, the copper content of the copper / tin / silver alloy ranges from 40 wt% to 60 wt% and has tin in the amount of 15 wt% to 50 wt% and the balance silver. The copper content of the copper / tin alloy ranges from 40 wt% to 70 wt% and has the remaining tin. This weight is based on measurements taken with an atomic absorption spectrometer ("AAS"), X-ray fluorescence ("XRF"), inductively coupled plasma ("ICP") or differential scanning calorimetry ("DSC").

In addition to providing a bright white bronze deposit, the copper alloy also contains a finish layer of gold, silver, palladium and chromium. After the white bronze is plated on the substrate, the finish layer of gold, silver, palladium or chromium (III) or (VI) is plated directly onto the bright white bronze without any preparation or other intervening steps such as ultrasonic cleaning or cathodic degreasing . Conventional gold, silver, palladium or chromium plating baths can be used according to conventional plating parameters. Such a finish layer may range in thickness from 0.05 [mu] m to 10 [mu] m.

Copper alloy electroplating deposits copper / tin alloys and copper / tin / silver alloys with high current efficiency and high plating rates in contrast to many conventional copper alloy plating baths that are stable over time and electroplating white bronze. The current efficiency ranges from 90% with an average value of 95% to as high as 100%. Copper / tin alloys and copper / tin / silver alloys electroplated from a plating bath have good ductility, thermal stability and abrasion resistance. The copper / alloy can be plated directly with gold, chromium (III) or (VI), palladium and silver finishes without conventional post-processing steps such as ultrasonic cleaning or cathodic degreasing of many conventional processes. Thus, cyanide-free copper alloy electroplating enables a more efficient process than many conventional cyanide-free white bronze processes and is suitable, for example, for nickel replacement for decorative and sanitary articles.

The following examples are intended to further illustrate the invention, but are not intended to limit the scope of the invention.

Example 1

Triple white bronze of copper / tin / silver

The following aqueous acid white bronze electroplating bath was prepared:

[Table 1]

¹ Adeka Tol PC-8: Non-ionic surfactant available from Adeka Corporation.

The pH of the plating bath was less than 1 as measured using a KNICK Instruments conventional laboratory pH meter. The molar masses of tetrazole compounds, 3,6-dithia-1,8-octanediol and copper (I) ions were 173.24, 182.30 and 63.55 g / mol, respectively. The molar ratio of the tetrazole to the copper (I) ion in the plating bath (i.e., the molar ratio of tetrazole to the copper (I) ion) was 1.2: 1, and the molar ratio of tetrazole to 3,6- The molar ratio to 8-octanediol (i.e., the number of moles of tetrazole: the number of moles of 3,6-dithia-1,8-octanediol) was 1.3: 1.

Dimensions 10 x 7.5 x 0.025 cm the use of brass for RONACLEAN ^™ DLF cleaning solution panel (available from Dow Electronic Materials) by having and degreasing as a cathode at 4 ASD for one minute RONASALT ^™ 369 solution (available from Dow Electronic Materials) To activate the substrate. The panel was then placed in a Hull cell containing 250 mL of a white bronze plating bath. A platinumized titanium electrode was used as the cathode material. The operating plating bath temperature was in the range of 35 ° C to 45 ° C with optimum panel brightness at about 40 ° C over a wide current density range. The panel was electroplated with a white bronze plating bath at 0.5 A for 5 minutes. After the electroplating was completed, the panel was removed from the plating cell and rinsed with DI water. The deposition on the panel was brighter in both of the following current densities of the Hull cell test: 0.05 ASD, 0.2 ASD, 0.5 ASD, 0.73 ASD, 1 ASD, 2 ASD and 2.5 ASD.

Two brass panels having the above dimensions were placed with two bronze anodes in a plating bath containing 2 liters of a white bronze plating bath in Table 1. 1 ASD current density was applied to one panel for 15 minutes and 2 ASDs were applied to the second panel for 10 minutes. The thickness of white bronze on each panel was 10 μm. The plating was carried out until a plating bath life of 15 Ah / L was reached. There was no observable degradation of the plating bath composition throughout the electroplating, no observable non-uniform precipitation or loss of plating performance. After the electroplating was completed, the panel was removed from the plating cell, rinsed with deionized water, and its appearance was visually observed. All panels were bright. The plating bath of this example was still stable after idling for one month.

Example 2

Double white bronze of copper / tin

The following aqueous acid white bronze electroplating bath was prepared:

[Table 2]

² Adeka Tol PC-8: Non-ionic surfactant available from Adeka Corporation.

The pH of the plating bath was less than 1 as measured using a KNICK Instruments conventional laboratory pH meter. The molar ratio of tetrazole to copper (I) ion in the plating bath was 1.1: 1 and the molar ratio of tetrazole to thiodiethanol was 0.4: 1.

Brass panels with dimensions of 10 x 7.5 x 0.025 cm were activated by degassing the cathode at 4 ASD for 1 minute with RONACLEAN ^™ DLF solution and immersing the substrate in RONASALT ^™ 369 solution for 20 seconds. The panel was then placed in a hull cell containing 250 mL of a white bronze plating bath. A platinumized titanium electrode was used as the cathode material. The operating plating bath temperature was in the range of 30 占 폚 to 40 占 폚, which is optimum at about 35 占 폚. The panel was electroplated with a white bronze plating bath at 0.5 A for 5 minutes. The plating baths appeared stable throughout the electroplating and the deposits were bright at all of the following current densities of the Hull cell test: 0.05 ASD, 0.2 ASD, 0.73 ASD, 1 ASD, 2 ASD and 2.5 ASD.

Two brass panels of this dimension were placed with two bronze anodes in a plating bath containing 2 liters of a white bronze plating bath in Table 2. [ 1 ASD current density was applied to one panel for 15 minutes and 2 ASDs were applied to the second panel for 10 minutes. The thickness of white bronze on each panel was 10 μm. The plating was carried out until a plating bath life of 15 Ah / L was reached. There was no observable degradation of the plating bath composition throughout the electroplating, no observable non-uniform precipitation or loss of plating performance. After the electroplating was completed, the panel was removed from the plating cell, rinsed with deionized water, and its appearance was visually observed. All panels were bright. The plating bath of this example was still stable after idling for one month.

Example 3

Tetrazole / 3,6-dithia-1,8-octanediol molar ratio in a copper / tin / silver electroplating bath

A white bronze copper / tin / silver alloy electroplating bath was prepared as described in Example 1 except that the amount of 3,6-dithia-1,8-octanediol was changed as shown in Table 3 below. The molar ratio of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole to 3,6-dithia-1,8-octanediol was as shown in Table 3 .

A number of brass panels having dimensions of 10 x 7.5 x 0.025 cm were degreased and activated as described in Example 1 above. Each panel was then placed in a separate hull cell containing 250 mL of a white bronze plating bath. The pH of the plating bath was less than 1. A platinumized titanium or bronze electrode was used as the cathode material. The operating plating bath temperature was in the range of 35 캜 to 45 캜. The panel was electroplated from 1 A to a white bronze plating bath for 3 minutes. All plating baths throughout the electroplating were found to be stable.

After electroplating, the panel was removed from the hull cell, washed with deionized water, and its appearance was visually observed. As shown in the following Table 3, the combination of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole and 3,6-dithia-1,8-octanediol All of the copper / tin / silver electroplating baths, which did not contain copper, exhibited undesirable matte deposits at all current densities.

[Table 3]

Although there was a plated panel with a formulation comprising a combination of tetrazole and octanediol with a matte deposit at some higher current density, the majority of deposits were bright.

Example 4

The molar ratio of tetrazole / thiodiethanol in the copper / tin electroplating bath

A white bronze copper / tin alloy electroplating bath was prepared as described in Example 2 except that the amount of thiodiethanol was changed as shown in Table 4 below. The molar ratio of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole to thiodiethanol was as shown in Table 4.

A number of brass panels having dimensions of 10 x 7.5 x 0.025 cm were degreased and activated as described in Example 2. Each panel was then placed in a separate hull cell containing 250 mL of a white bronze plating bath. A platinumized titanium or bronze electrode was used as the cathode material. The operating plating bath temperature was set in the range of 30 占 폚 to 40 占 폚. The panel was electroplated from 1 A to a white bronze plating bath for 3 minutes. All plating baths throughout the electroplating were found to be stable.

After electroplating, the panel was removed from the hull cell, washed with deionized water, and its appearance was visually observed. As shown in the following Table 4, copper / tin electroplating baths without the combination of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole and thiodiethanol Exhibited undesirable matt deposition at all current densities. The electroplated panel with a plating bath comprising a combination of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole and thiodiethanol in a molar ratio of 2.96 to a lower current The plating baths with bright ratios in the density range, while having a molar ratio of 1.14, had bright deposits at higher current densities and the plating baths with a molar ratio of less than 1.14 had significant bright deposits at all current densities.

[Table 4]

Example 5 (Comparative Example)

Copper (II) bronze formulations

Three copper (II) bronze electroplating baths were prepared as shown in Table 5 below.

[Table 5]

³ Adeka Tol PC-8: Non-ionic surfactant available from Adeka Corporation.

The molar ratio of 1- (2-dimethylamino-ethyl) -5-mercapto-1,2,3,4-tetrazole to copper (II) ion was 0.15: 1 in the comparative plating bath 1, And the comparison plating bath 3 was 1.1: 1.

A number of brass panels having dimensions of 10 x 7.5 x 0.025 cm were degreased and activated. Each panel was then placed in a separate hull cell containing 250 mL of one of the three copper / tin plating baths. The pH of the plating bath was less than 1. A platinumized titanium or bronze electrode was used as the cathode material. The manipulation plating bath was kept at 35 캜 in the plating process. The panel was electroplated with a copper / tin plating bath at 1 A for 3 minutes. The panel was electroplated, washed with deionized water, and its appearance was visually observed. The results for each plating bath are shown in Table 5a.

[Table 5a]

The comparative plating baths 1 and 2 have good bright deposits at all current densities while the comparative plating baths 3 have a very low current density of less than 30% and a copper content of more than 70%, as shown by the thin deposits, Yellow bronze deposits.

Comparative plating baths 1 and 2 were idled for 24 hours. The new set of panels was then electroplated with comparison plating baths 1 and 2. Because of the unfavorable results from the comparative plating solution 3, its plating performance was not tested for performance after 24 hours idling time. The results of comparative plating solutions 1 and 2 are shown in Table 5b.

[Table 5b]

Plated matt bronze deposits after 24 hour idling time indicated that the plating bath was unstable. By adding an additional amount of tin (II) ions in an amount of half the original concentration to the plating bath, the brightness was restored; However, tin (II) was rapidly oxidized to tin (IV) as indicated by the orange color of the plating bath.

Example 6

Hull cell test for copper / tin / silver alloy composition

A 10 x 7.5 x 0.025 cm steel panel was immersed in 40% hydrochloric acid solution for 1 minute to remove the zinc protective layer on its surface. The panel was degassed in a RONACLEAN ( ^TM) DLF cleaning solution for 3 minutes at 3 ASD for 1 minute. The panel was activated by dipping in the RONASALT ^™ 369 solution, washed with deionized water and placed in a Hull cell containing the white bronze plating bath of 250 mL as described in Example 1 above. A platinumized titanium electrode was used as the anode. The molar ratio of tetrazole to copper (I) ion in the plating bath (ie, mole number of tetrazole: mole number of copper (I) ion) was 1.2: 1 and tetrazole 3,6-dithia-1,8 To-octanediol (i.e., the number of moles of tetrazole: the number of moles of 3,6-dithia-1,8-octanediol) was 1.3: 1.

The alloy compositions were measured in steel hull cells plated at 0.5 A current for 5 minutes at different current densities as shown in Table 6 below. The metal content was measured by XRF using a FISCHERSCOPE X-Ray model XDV-SD from Helmut Fischer AG. This measurement was repeated on three different steel panels coated with white bronze. The average metal content at each current density is shown in Table 6.

[Table 6]

All alloys had a bright appearance when viewed with the naked eye.

Example 7

Copper (I) Copper / tin / silver alloy Electroplating Copper (II) Copper / tin alloy Electroplating Plating speed

A 1-liter white bronze plating bath of Example 1 was injected into the glass cell. Two platinumized titanium anodes were placed in the cell. A 12 mm diameter and 7 mm high steel cylinder ring was secured to the rotating shaft of the electric motor. The rotational speed of the shaft was fixed at 1000 rpm. The shaft was immersed in a plating bath and electrical contact was established between the electrodes. The current density was varied and the plating rate was measured for the same electroplating bath as well as the new electroplating bath at different plating bath life as shown in Table 7a. At each current density, the thickness of the bronze coating was measured using XRF. The thickness of the plated white bronze in microns was divided by the plating time in minutes, and the plating rate was calculated at each current density. Results are presented in microns per hour.

[Table 7a]

As indicated by the results in Table 7a, the plating rate increased with increasing current density and remained substantially constant at each current density regardless of the lifetime of the plating bath. This indicates that electroplating is stable and its performance is reliable during its life. In order to complete the plating process, it is not necessary to dispose of the original electroplating bath and use a new plating bath.

The process was repeated with a copper (II) comparison plating bath in Table 7b below at a plating bath life of 0 Ah / L and 10 Ah / L. The results are shown in Table 7c.

[Table 7b]

³ LUGALVAN® IZE (available from BASF)

⁴ PLURONIC® PE 6400 (available from BASF)

[Table 7c]

The plating rate was substantially stable to the plating bath life; However, the speed at most current densities was lower compared to the results in Table 7a. This indicated that the current efficiency in the copper (II) comparison plating bath was lower than that in Example 1.

Example 8

Current efficiency of copper / tin / silver alloy plating bath

The current efficiency of the white bronze electroplating bath of Example 1 was estimated by multiplying all of the experimental masses of the deposits divided by the theoretical mass by 100. Experimental mass was determined by measuring the mass difference of 5 x 7.5 x 0.025 cm brass panels before and after white bronzing. The theoretical mass of the deposit was calculated based on Faraday's law and considering the alloy composition. This method is described in Frederick Adolph Lowenheim , Electroplating (1978) page 377, Library of Congress Cataloging, McGraw-Hill Book Company: ISBN 0-07-038836-9 .

The current efficiency was determined at a high current density of 2 ASD over a plating bath life of 0 Ah / L to 15 Ah / L. Multiple estimations were made over the lifetime of the plating bath as shown in the graph of FIG. 1 for the% CE versus plating bath life. The current efficiency ranged from 90% to 100%, which is an average of about 95%. Values above 100% were due to possible experimental errors. The high and stable current efficiency lasted over the life of the plating bath exhibited a very stable electroplating bath where undesired hydrogen evolution was of no significance.

Example 9

Ductility measurement of white bronze from copper (I) copper / tin / silver plating bath to copper (II) copper / tin plating bath

Three 2 x 10 x 0.025 cm brass panels were electroplated with the white bronze electroplating bath of Example 1 and the other three were electroplated with a copper (II) copper / tin bronze alloy plating bath of Table 8 below. Two liters of each bronze plating bath was added to a separate electrochemical cell. Two white bronze anodes were also placed in the cell. 1 The ASD electrical current density was applied between the anode and the brass cathode for 5 minutes to deposit a 3 탆 thick layer on each brass panel. The plating time was 7 minutes for the formulation in Table 8. The deposits appeared bright.

[Table 8]

³ LUGALVAN® IZE (available from BASF)

⁴ PLURONIC® PE 6400 (available from BASF)

The ductility of each plated brass panel was tested using a bend-tester from SHEEN INSTRUMENTS Ltd. according to ASTM standard B 489-85. The average ductility was determined for each set of three panels. The average ductility for the white bronze of the plating bath from Example 1 was 1.2% elongation. Cracks were found in the deposits when this number was exceeded. Cracks were observed at an elongation of 0.8% for the deposits from the formulations in Table 8. 0.8% is the lower scale for the ductility test when using the instrument. The test was repeated except that the amount of electroplated white bronze on the brass panel was 6 [mu] m. The average elongation for the plating bath from Example 1 was again 1.2% and the cracks were observed at 0.8% from the samples plated with the plating bath of Table 8. The white bronze deposits from Example 1 exhibited improved ductility in contrast to the plating baths from Table 8.

Example 10

Thermal Stability of White Bronze

Six 2 x 10 x 0.025 cm brass panels were electroplated with the white bronze electroplating bath of Example 1 and three were electroplated with the copper (II) copper / tin bronze alloy plating bath of Table 8 from Example 9 Respectively. Two liters of each bronze plating bath was added to a separate electrochemical cell. Two white bronze anodes were also placed in the cell. A current density of 1 ASD was applied between the anode and the brass cathode for 4 minutes to plated a 3 탆 thick layer on each brass panel. Two panels plated with a plating bath containing the formulation of Example 1 and two panels plated with the formulation of Table 8 were placed in a conventional laboratory oven from BINDER ( ^TM) Inc. at 150 ° C for 24 hours. The remaining plated brass panels were kept at room temperature for control without annealing. After 24 hours, the brass panels were removed from the oven and visually inspected according to the non-annealed panel. The panels plated with the white bronze plating bath from Example 1 and those left at room temperature were bright; However, the panel plated and annealed with the plating bath from Table 8 had an undesirable blue appearance.

The test was repeated at 200 < 0 > C for 2 hours. The panel electroplated with the white bronze plating solution of Example 1 was again brighter, like the control panel. In contrast, the panel electroplated and annealed with the plating bath from Table 8 had a deep dark color. The white bronze electroplated from the plating bath of Example 1 exhibited improved heat resistance to the conventional plating bath of Table 8.

Example 11

Top layer deposition on white bronze of copper / tin / silver alloy

Three 2 x 10 x 0.025 cm brass panels were electroplated with the white bronze electroplating bath of Example 1 and the other three were electroplated with the copper (II) copper / tin bronze alloy plating bath of Example 9. Two liters of each bronze plating bath was added to a separate electrochemical cell. Two white bronze anodes were also placed in the cell. 1 The ASD electrical current density was applied between the anode and the brass cathode for 5 minutes to deposit a 3 탆 thick layer on each brass panel. The deposits appeared bright.

Available from Dow Electronic Materials, RONAFLASH ^™ P gold electroplating was placed in a separate plating bath of the electrochemical cell. The white bronze plated brass panel was rinsed with deionized water and placed in a gold plating bath. The panel was then electroplated with gold without any further surface treatment or preparation prior to gold plating. 1 ASD was applied for 40 seconds between a bronze coated brass panel and a plated titanium anode. The panel was removed, rinsed with deionized water and dried with pressurized air. All deposits had a shiny gold appearance. The panel was kept outdoors at room temperature for one month. The sample electroplated with the plating bath of Example 1 was still shiny. In contrast, the panel plated with the plating bath of Example 9 appeared to be colored with several non-shiny portions present on the surface.

The CHROME GLEAM ^™ available purchased panel in place of the gold plating on the panel from Dow electronic Materials 3C chrome (III) electroplating using a plating bath was, except that the chromium plating, and repeat the process described. The current density was 10 ASD and plating was performed for 3 minutes. Glossy chrome colors were deposited on the white bronze of each panel. The panel was exposed outdoors at room temperature for one month. No stains were observed on the panel containing the white bronze plated with the formulation of Example 1. Figure 2 is a photograph taken with an OLYMPUS BX60M optical microscope of one of the panels. The chromium deposit was clean. In contrast, all of the panels plated with the plating bath from Example 9 had unsightly stains. 3 is a photograph of one of the panels plated with a plating bath from Example 9 taken with an OLYMPUS BX60M optical microscope. Severe contamination of chromium deposits is evident. The panel electroplated with the white bronze plating bath of Example 1 showed a significant improvement in resistance to contamination in contrast to conventional bronze plating baths.

Claims (7)

At least one copper (I) ion source;
One or more alloying tin ion sources;
Optionally, the at least one alloying comprises an ion source;
4-thiodiphenol, 4,4'-thiobis (2-methyl-6-tert-butylphenol), thiodiethanol, 2,4-dithia- Dithia-1,6-hexanediol, 2,6-dithia-1,7-heptanediol, 2,7-dithia-1,8-octanediol, Nonadiol, 2,9-dithia-1,10-decanediol, 2,11-dithia-1,12-dodecanediol, 5,8-dithia-1,12-dodecanediol, 2,15 Dithia-1,16-hexadecanediol, 2,21-dithia-1,22-doeic acid diol, 3,5-dithia-1,7-heptanediol, 3,6- Octadiol, 3,8-dithia-1,10-decanediol, 3,10-dithia-1,8-dodecanediol, 3,13-dithia-1,15-pentadecanediol, 3 Dithia-1,10-decanediol, 4, 11-dithia-1, , 14-tetradecanediol, 4,15-dithia-1,18-octadecanediol, 4,19-dithia-1,22-toeicosanediol, 5,7-dithia-1,11-undecane Diol, 5,9-dithia-1,13-tridecanediol, 5,13-dithia-1,17-heptadecanediol, 5,17-dithia-1,21- And 1,8-dimethyl-3,6-dithia-1,8-octanediol; And
1- (2-diethylaminoethyl) -5-mercapto-1,2,3,4-tetrazole, 1- (3-ureidophenyl) -5- (4-acetamidophenyl) -5-mercapto-tetrazole and 1- (4-carboxyphenyl) -5-mercaptotetrazole At least one tetrazole selected from sols,
Wherein the molar ratio of the at least one tetrazole to the copper (I) ion in the electroplating bath is at least 1 and the molar ratio of the at least one tetrazole to the at least one sulfur compound is from 0.05 to 4,
Cyanide-free electrochemistry. a) at least one copper (I) ion source; One or more alloying tin ion sources; Optionally, the at least one alloying comprises an ion source; 4-thiodiphenol, 4,4'-thiobis (2-methyl-6-tert-butylphenol), thiodiethanol, 2,4-dithia- Dithia-1,6-hexanediol, 2,6-dithia-1,7-heptanediol, 2,7-dithia-1,8-octanediol, Nonadiol, 2,9-dithia-1,10-decanediol, 2,11-dithia-1,12-dodecanediol, 5,8-dithia-1,12-dodecanediol, 2,15 Dithia-1,16-hexadecanediol, 2,21-dithia-1,22-doeic acid diol, 3,5-dithia-1,7-heptanediol, 3,6- Octadiol, 3,8-dithia-1,10-decanediol, 3,10-dithia-1,8-dodecanediol, 3,13-dithia-1,15-pentadecanediol, 3 Dithia-1,10-decanediol, 4, 11-dithia-1, , 14-tetradecanediol, 4,15-dithia-1,18-octadecanediol, 4,19-dithia-1,22-toeicosanediol, 5,7-dithia-1,11-undecane Diol, 5,9-dithia-1,13-tridecanediol, 5,13-dithia-1,17-heptadecanediol, 5,17-dithia-1,21- And 1,8-dimethyl-3,6-dithia-1,8-octanediol; And 1 - ((3-thienylaminoethyl) -5-mercapto-1,2,3,4-tetrazole, 1- (4-acetamidophenyl) -5-mercapto-tetrazole and 1- (4-carboxyphenyl) -5-mercapto Tetrazole, wherein the molar ratio of the at least one tetrazole to the copper (I) ion in the electroplating bath is at least 1, and wherein the at least one tetra Contacting the substrate with a cyanide-free electroplating bath having a sol molar ratio of from 0.05 to 4, and
b) electroplating a copper / tin alloy or optionally a copper / tin / silver alloy onto said substrate.
Electroplating method. The electroplating method of claim 2, further comprising electroplating a finish layer of silver, gold, palladium or chromium on the copper / tin alloy or the copper / tin / silver alloy. delete delete delete delete

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