TWI609102B - Cyanide-free electroplating baths for white bronze based on copper (i) ions - Google Patents

Description

Cyanide-free electroplating bath for white bronze based on copper (I) ions

This invention relates to a cyanide-free electroplating bath for white bronze based on copper (I) ions. More specifically, the present invention relates to copper (I) ion-based electroplating baths for white bronze that are stable and electroplated with bright white bronze deposits.

White bronze is often used as a material for nickel replacement in the decorative and sanitary industries. In general, bronze is 40% to 70% by weight of copper, and the remainder is tin or tin and silver or tin and zinc. It is hard enough to provide adequate wear and corrosion resistance, making it a replacement for nickel in both decorative and hygienic functions. Currently, most industrial white bronzes are not only toxic due to cyanide inclusions, but also have relatively slow plating rates from 0.1 ASD to about 2 ASD, and low current efficiencies in the range of 50% to 80%.

U.S. 7,780,839 to Egli et al. is a cyanide-free white bronze which can be used as a substitute for the conventional cyanide-containing white bronze electroplating bath. Although the plating speed of this electrolyte is significantly improved compared to many conventional white bronze plating baths, However, white bronze deposits may be slightly brittle and cannot pass the grinding test. It may also be difficult to plate a top layer of white bronze, such as gold, chromium (III) or (VI), palladium or silver. When top-coating articles for decorative and sanitary applications, the general process consists of degreasing the articles using conventional degreased formulations, rinsing with water, followed by thick copper plating for leveling purposes, and subsequent plating from the cyanide-containing bath. Bronze, rinsed with water, then plated with gold, chromium (III) or (VI), palladium or silver finish on white bronze. When a cyanide-free white bronze electroplating bath is used as in U.S. 7,780,839, an additional step is typically required prior to plating the finishing layer. An organic film of unknown composition may be formed on white bronze after plating, which is detrimental to the surface appearance of white bronze. An ultrasonic rinse or cathodic degreasing step is included in the process to remove the film prior to plating the finish. This extra step reduces the efficiency of the overall process and increases the cost because an ultrasonic device must be installed or a separate tank with a current supply is required in the case of cathodic degreasing. Therefore, there is still a need for an improved white bronze electroplating bath and process.

An electroplating bath comprising one or more copper (I) ion sources, one or more alloy tin ion sources, optionally one or more alloy silver ion sources, one or more compounds having the formula: X-S-Y (I)

Wherein X and Y may be the same or different and may be substituted or unsubstituted phenolic, HO-R- or -R'S-R"-OH, wherein R, R' and R" may be the same or different and have 1 a linear or branched alkyl group of up to 20 carbon atoms; and one or more tetrazole, wherein the one or more tetrazole in the electroplating bath is more than the molar ratio of the copper (I) ion 1. The one or more tetrazoles have a molar ratio of from 0.05 to 4 to the one or more compounds of formula (I), and the electroplating bath is cyanide-free.

An electroplating method comprising: contacting a substrate with an electroplating bath comprising one or more copper (I) ion sources, one or more alloy tin ion sources, optionally one or more alloy silver ion sources, one or more having Compound: XSY (I)

Wherein X and Y may be the same or different and may be substituted or unsubstituted phenolic, HO-R- or -R'S-R"-OH, wherein R, R' and R" may be the same or different and may have a linear or branched alkyl group of 1 to 20 carbon atoms; and one or more tetrazole, wherein the one or more tetrazole in the electroplating bath is more than the molar ratio of the copper (I) ion And the one or more tetrazole has a molar ratio of 0.05 to 4 to the one or more compounds of formula (I), the electroplating bath is cyanide-free; and electroplating copper on the substrate Tin alloy or copper/tin/silver alloy.

The cyanide-free copper alloy plating bath deposits a bright white bronze copper/tin alloy or a copper/tin/silver alloy. The copper alloy electroplating bath is stable over a long period of time and is capable of depositing copper/tin alloy and copper/tin/silver at high current efficiency and high plating speed as opposed to many conventional copper alloy baths of electroplated white bronze. alloy. The copper/tin alloy and copper/tin/silver alloy electroplated from the bath have good ductility, thermal stability and wear resistance. The copper/alloy can be directly plated with gold, chromium (III) or (VI), palladium and silver finishes without many of the conventional post-processing steps of conventional processes, such as ultrasonic rinsing or cathodic degreasing. Therefore, the cyanide-free copper alloy plating bath achieves more than many conventional cyanide-free white bronze processes. Effective process and can be used for nickel replacement.

Figure 1 is a graph showing the current efficiency % of a cyanide-free copper/tin/silver alloy plating bath compared to the bath life.

Figure 2 is a photograph of a layer of chromium on a white bronze deposit electroplated from a copper (I)-free plating bath containing no cyanide after one month at room temperature.

Figure 3 is a photograph of a layer of chromium on a cyanide-free white bronze deposit electroplated from a copper (II) containing bath after one month at room temperature.

As used throughout the specification, the following abbreviations have the following meanings unless the context clearly indicates otherwise: °C = degrees Celsius; g = grams; cm = centimeters; mL = milliliters; L = liters; mg = milligrams; ppm = parts per million Rate=mg/L; DI=deionization; μm=micron; mol=mole; wt%=weight percentage; A=amperage; A/dm ² and ASD=ampere/square inch; Ah=ampere hour; = current efficiency percentage; rpm = rev / min; IEC = International Electrochemical Commission; XRF = X-ray fluorescence; and ASTM = American Standard Test Method. The plating potential is provided relative to the hydrogen reference electrode. With regard to the electroplating process, the terms "depositing", "coating", "electroplating" and "plating" are used interchangeably throughout this specification. "Halocarbon" means fluoride, chloride, bromide and iodide. All percentages are by weight unless otherwise indicated. All numerical ranges are inclusive and may be combined in any order, but logically stated in the numerical range is understood to mean a total of 100%.

Copper (I), silver, tin, and copper (I) and tin alloy plating baths are substantially free of cyanide. Cyanide is primarily avoided by the absence of any silver or tin salts or other compounds in the bath containing CN ^- anions. The copper (I), silver, tin, and copper (I) and tin alloy plating baths are also substantially free of copper (II) ions to enable the copper alloy plating bath to plate bright white bronze deposits.

Copper (I) ion sources include, but are not limited to, cuprous salts such as cuprous oxide, cuprous chloride, cuprous bromide, cuprous iodide, and cuprous ammonium salts such as cuprous ammonium chloride. Copper (I) salts are generally commercially available or can be prepared by methods described in the literature. When cuprous oxide is used, the alkane or arylsulfonic acid or a mixture thereof is preferably contained in the bath. A sufficient amount of one or more copper (I) salts is included in the bath such that the amount of copper (I) ions can 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 sulfates, stannous sulfonates, stannol sulfonates, and acids. When a tin halide is used, the halide is typically a chloride. The tin compound is preferably tin sulfate, tin chloride or tin alkane sulfonate, and more preferably tin sulphate or tin methane sulfonate. Tin compounds are generally commercially available or can be prepared by methods known in the literature. Preferably, the tin salt is readily water soluble. The amount of tin salt used in the bath depends on the desired composition and operating conditions of the alloy to be deposited. A sufficient amount of tin salt is included in the bath to provide tin ions in the range of from 1 g/L to 100 g/L, preferably from 5 g/L to 50 g/L.

Silver ion sources include, but are not limited to, silver halides, silver gluconate, silver citrate, silver lactate, silver nitrate, silver sulfate, silver alkane sulfonates, and silver alkanols. Sulfonate. When a silver halide is used, it is preferred that the halide be a 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 one or more silver salts used in the bath depends, for example, on the desired alloy composition and operating conditions to be deposited. A sufficient amount of silver salt is included in the bath to provide silver ions in the range of from 0.01 g/L to 100 g/L, preferably from 0.5 g/L to 50 g/L.

The copper (I) alloy plating bath contains one or more sulfur compounds having the formula: X-S-Y (I)

Wherein X and Y may be substituted or unsubstituted phenolic, HO-R- or -R'-SR"-OH, wherein R, R' and R" are the same or different and have from 1 to 20 carbon atoms A straight or branched chain of alkyl groups. Substituents on the phenol include, but are not limited to, straight or branched (C ₁ -C ₅ )alkyl groups. The compound can act as a complexing agent for copper (I) ions.

Examples of the compounds wherein 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 following formula: HO-R-S-R'-S-R"-OH (II)

Wherein R, R' and R" are the same or different and are a straight or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 2 to 10 of R and R" A carbon atom and R' has 2 carbon atoms. The compound is referred to as a dihydroxy disulfide compound. Preferably, the dihydroxy disulfide compound is included in the alloy bath containing the phenolic compound.

Examples of the dihydroxydisulfide compound are 2,4-dithia-1,5-pentanediol, 2,5-dithia-1,6-hexanediol, 2,6-dithia -1,7-heptanediol, 2,7-dithia-1,8-octanediol, 2,8-dithia-1,9-nonanediol, 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-docosanediol, 3,5-dithia-1,7-heptanediol, 3,6- Dithia-1,8-octanediol, 3,8-dithia-1,10-nonanediol, 3,10-dithia-1,8-dodecanediol, 3,13- Dithia-1,15-pentadecanediol, 3,18-dithia-1,20-eicosanediol, 4,6-dithia-1,9-nonanediol, 4, 7-Dithia-1,10-decanediol, 4,11-dithia-1,14-tetradecanediol, 4,15-dithia-1,18-octadecanediol, 4,19-dithia-1,22-docosanediol, 5,7-dithia-1,11-undecanediol, 5,9-dithia-1,13-ten Trialkyl diol, 5,13-dithia-1,17-heptadecanediol, 5,17-dithia-1,21-docosanediol and 1,8-dimethyl- 3,6-Dithia-1,8-octanediol.

The copper (I) alloy bath also contains one or more tetrazole as a copper (I) ion misc. The tetrazole is a heterocyclic nitrogen compound having a five-membered ring and having at least one sulfur substituent on the ring. While not being bound by theory, tetrazole together with the compounds of formula (I) and (II) inhibits the oxidation of copper (I) ions to copper (II) ions and stabilizes the bath. Inhibiting the oxidation of copper (I) ions to copper (II) ions facilitates the formation of copper/tin/silver or copper/tin alloys. The tetrazole is contained in the bath such that the tetrazole in the bath is more than the copper (I) ion molar ratio 1, preferably >1, more preferably >1 to 10, even more preferably >1 to 6, and most preferably 1.1 to 4. In general, the amount of tetrazole contained in the bath may range from 0.5 g/L to 500 g/L.

The compounds of formula (I) and (II) are contained in a bath such that The molar ratio of the compound of formula (I) or (II) to the various tetrazole is from 0.05 to 4, preferably from 0.1 to 3.

Preferably, the tetrazole is a mercaptotetrazole compound having the formula:

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 group, substituted or unsubstituted (C ₆ -C ₁₀ ) an aryl group, preferably a substituted or unsubstituted linear or branched (C ₂ -C ₁₀ ) alkyl group and a substituted or unsubstituted (C ₆ ) aryl group, more preferably substituted or Unsubstituted linear or branched (C ₂ -C ₁₀ ) alkyl. Substituents include, but are not limited to, alkoxy, phenoxy, halogen, nitro, amine, substituted amine, sulfo, sulfonyl, substituted sulfonyl, sulfophenyl , sulfhydryl-alkyl, fluorosulfonyl, sulfonylaminophenyl, sulfonamide-alkyl, carboxyl, carboxylate, ureidoamine, amine, mercapto-phenyl, amine Mercaptoalkyl, carbonylalkyl and carbonylphenyl. Preferred substituents include an amine group and a substituted amine group. Examples of mercaptotetrazole are 1-(2-diethylaminoethyl)-5-mercapto-1,2,3,4-tetrazole, 1-(3-ureidophenyl)-5-fluorenyltetrayl Oxazole, 1-((3-N-ethylethylenediamine)phenyl)-5-mercaptotetrazole, 1-(4-ethylamidophenyl)-5-mercapto-tetrazole and 1- (4-Carboxyphenyl)-5-mercaptotetrazole.

The combination of one or more tetrazoles and a compound of formula (I) or (II) provides stability to the alloy bath during storage or during electroplating and a stable alloy composition over a range of applicable current densities such that hard bright copper can be deposited /tin/ Silver or copper/tin alloy as a replacement for nickel in decorative or sanitary articles.

Any aqueous soluble acid that does not otherwise adversely affect the bath can be used. 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, amine sulfonic acid, hydrochloric acid, hydrobromic acid and fluoroboric acid. Typically, the acid is an alkane sulfonic acid and an aryl sulfonic acid. A single acid is typically used, although a mixture of acids can be used. The acid is usually commercially available or can be prepared by methods known in the literature.

The amount of acid in the plating composition may range from 0.01 to 500 g/L or such as from 10 to 400 g/L, depending on the desired alloy composition and operating conditions. When silver ions and tin ions are derived from metal halides, it may be necessary to use the corresponding acid. For example, when one or more of tin chloride or silver chloride is used, it may be necessary to use hydrochloric acid as the acid component. A mixture of acids can also be used.

Optionally, one or more inhibitors may be included in the 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. The inhibitors include, but are not limited to, alkanolamines, polyethylenimines, and alkoxylated aromatic alcohols. Suitable alkanolamines include, but are not limited to, substituted or unsubstituted methoxylated, ethoxylated and propoxylated amines such as tetrakis(2-hydroxypropyl)ethylenediamine, 2-{[ 2-(Dimethylamino)ethyl]-methylamino}ethanol, N,N'-bis(2-hydroxyethyl)-ethylenediamine, 2-(2-aminoethylamine)- Ethanol and combinations thereof.

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

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

Optionally, one or more reducing agents may be added to the bath to help maintain the tin in a soluble divalent state. Suitable reducing agents include, but are not limited to, hydroquinone, hydroquinone sulfonic acid, potassium salts, and hydroxylated aromatic compounds such as resorcinol and catechol. The reducing agent is present in the composition 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 ability, one or more conventional surfactants can be included in the bath. Surfactants include, but are not limited to, ethylene oxide and/or propylene oxide derivatives of fatty alcohols containing one or more alkyl groups, or ethylene oxide and or propylene oxide derivatives of aromatic alcohols. The fatty alcohol can be saturated or unsaturated. The fatty alcohol and the aromatic alcohol may be further substituted with, for example, a sulfate or sulfonate group. Surfactants can be included in conventional amounts. In general, the surfactant can be included in an amount from 0.1 g/L to 50 g/L.

Other optional compounds may be added to the bath to provide further grain refinement. The compound includes, but is not limited to, an alkoxylate such as a polyethoxylated amine JEFFAMINE T-403 or TRITON RW; or a sulfated alkyl ethoxylate such as TRITON QS-15; and gelatin or gelatin derived Things. Alkoxylated amine oxides can also be included. A conventional amount of the grain refiner can be used. Typically, it is included in the bath in an amount from 0.5 g/L to 20 g/L.

Other grain refiners include, but are not limited to, phenanthroline compounds such as 1,10-morpholine monohydrate; phosphonium salts such as cerium nitrate, cerium acetate, cerium tartrate, and decane sulfonate. Indium salts such as indium chloride, indium sulfate, and indium alkane sulfonic acid salt. Barium salts, such as barium lactate, barium potassium tartrate. Selenium and tellurium can be added in the form of a dioxide. Iron salts such as iron bromide and anhydrous ferric chloride. Cobalt salts such as cobalt nitrate, cobalt bromide and cobalt chloride. Zinc salts such as zinc lactate and zinc nitrate. Chromium salts such as chromous chloride and chromic formate. The grain refiner is included in conventional amounts. Generally, the grain refiner is included in an amount from 5 ppm to 1000 ppm.

Electroplating baths typically by adding one or more acids, one or more compounds of formula (I) and one or more tetrazole to the vessel, followed by the addition of one or more solutions of soluble copper (I), silver and tin compounds, one or A variety of additives are used depending on the situation and the rest of the water is prepared. Preferably, a compound of the formula (II) and a tetrazole are added to the vessel, followed by the addition of the copper (I) compound and the acid, followed by the addition of silver and a tin compound. After the aqueous bath is prepared, the undesired material can be removed, such as by filtration, and then water is typically added to adjust the final amount of the bath. The bath can be agitated by any known means such as stirring, pumping or recirculating to obtain an increased plating rate. The bath is acidic and has a pH of less than 7, preferably less than 3.

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

The copper/tin/silver and copper/tin alloys can be plated at room temperature to 60 ° C, preferably 30 ° C to 50 ° C. More preferably, the electroplating is carried out at a temperature of from 30 ° C to 45 ° C.

The bath can be used to deposit copper/tin/silver and copper/tin alloys of various compositions. In general, the copper/tin/silver alloy has a copper content in the range of 40% by weight to 60% by weight, tin in an amount of 15% by weight to 50% by weight, and the balance being silver. The copper/tin alloy has a copper content ranging from 40% by weight to 70% by weight, the remainder being tin. The weight is based on atomic absorption spectroscopy ("AAS"), X-ray fluorescence ("XRF"), inductively coupled plasma ("ICP"), or differential scanning calorimetry ("DSC"). Measurement value.

In addition to providing bright white bronze deposits, copper alloys also accept gold, silver, palladium and chrome finishes. After plating white bronze on the substrate, the gold, silver, palladium or chromium (III) or (VI) finishing layer can be directly plated on bright white bronze without any preparation or other intervention steps such as ultrasonic cleaning or cathodic degreasing. . Conventional gold, silver, palladium or chrome plating baths as well as conventional plating parameters can be used. The thickness of the finish layer may range from 0.05 μm to 10 μm.

The copper alloy plating bath is stable over a longer period of time and, in contrast to many conventional copper alloy baths of electroplated white bronze, deposits copper/tin alloys and copper/tin/silver alloys with high current efficiency and high plating speed. Current efficiency ranges from 90% up to 100% with an average of 95%. The copper/tin alloy and copper/tin/silver alloy electroplated from the bath have good ductility, thermal stability and wear resistance. The copper/alloy can be directly plated with gold, chromium (III) or (VI), palladium and silver finishes without many of the conventional post-processing steps of conventional methods, such as ultrasonic rinsing or cathodic degreasing. Thus, the cyanide-free copper alloy plating bath achieves a more efficient process than many conventional cyanide-free white bronze processes and is suitable for nickel replacement such as 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

Copper/tin/silver ternary white bronze

Prepare the following aqueous acid white bronze plating bath:

¹ Adeka Tol PC-8: a nonionic surfactant available from Adeka Corporation.

The pH of the bath was less than 1 as measured using KNICK Instruments' well-known laboratory pH meter. The molar masses of the tetrazole compound, 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 tetrazole to copper (I) ion in the bath was 1.2:1, and the molar ratio of tetrazole to 3,6-dithia-1,8-octanediol was 1.3:1.

The dimensions of 10 × 7.5 × 0.025cm brass panel RONACLEAN ^TM DLF by using a cleaning solution (available from Dow Electronic Materials) degreased at 4ASD cathode 1 min, and by immersing the substrate in a solution RONASALT ^TM 369 ( Activated in Dow Electronic Materials for 20 seconds. The panel was then placed in a Hull cell containing a 250 mL white bronze bath. A platinized titanium electrode is used as the anode material. The working bath temperature is in the range of 35 ° C to 45 ° C over a wide range of current densities with optimum panel brightness at about 40 ° C. The panel was plated with a white bronze bath at 0.5 A for 5 minutes. After the plating is completed, the panel is removed from the plating bath and rinsed with DI water. The deposits on the panel were bright at all 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 of the above dimensions were placed in a plating bath containing two bronze anodes containing a 2 liter white bronze bath in Table 1. A current density of 1 ASD was applied to one panel for 15 minutes, and 2 ASD was applied to the second panel for 10 minutes. The thickness of white bronze on each panel was 10 μm. Plating was carried out until a bath life of 15 Ah/L was reached. There is no observable decomposition of the bath components, observable abnormal precipitation or loss of plating efficiency throughout the plating. After the plating was completed, the panel was removed from the plating tank, rinsed with DI water, and the appearance was visually observed. All panels are rendered bright. The plating bath of this example was stable after one month of empty loading.

Example 2

Copper/tin binary white bronze

Prepare the following aqueous acid white bronze plating bath:

² Adeka Tol PC-8: a nonionic surfactant available from Adeka Corporation.

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

The dimensions of 10 × 7.5 × 0.025cm brass panel using RONACLEAN ^TM DLF 4ASD cathode degreasing solution at 1 min, and by immersing the substrate in RONASALT ^TM 369 was activated for 20 seconds. The panel was then placed in a Hull cell containing a 250 mL white bronze bath. A platinized titanium electrode is used as the anode material. The working bath temperature is in the range of 30 ° C to 40 ° C, most preferably at about 35 ° C. The panel was plated with a white bronze bath at 0.5 A for 5 minutes. The bath appeared to be stable throughout the plating and the deposits appeared bright at 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 of the above dimensions were placed in a plating bath containing two bronze anodes containing a 2 liter white bronze bath in Table 2. A current density of 1 ASD was applied to one panel for 15 minutes, and 2 ASD was applied to the second panel for 10 minutes. The thickness of white bronze on each panel was 10 μm. Plating was carried out until a bath life of 15 Ah/L was reached. There is no observable decomposition of the bath components, observable abnormal precipitation or loss of plating efficiency throughout the plating. After the plating was completed, the panel was removed from the plating tank, rinsed with DI water, and the appearance was visually observed. All panels are rendered bright. The plating bath of this example was stable after one month of empty loading.

Example 3

Tetrazolium/3,6-dithia-1,8-octanediol molar ratio in copper/tin/silver plating bath

A white bronze copper/tin/silver alloy plating bath was prepared as described in Example 1, except that the amount of 3,6-dithia-1,8-octanediol was varied as shown in Table 3 below. 1-(2-Dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole than 3,6-dithia-1,8-octanediol Shown in 3.

A plurality of brass panels of size 10 x 7.5 x 0.025 cm were degreased and activated as described in Example 1 above. The panels were then placed in separate Hull tanks containing a 250 mL white bronze bath. The pH of the bath is less than 1. A platinized titanium or bronze electrode is used as the anode material. The working bath temperature is in the range of 35 ° C to 45 ° C. The panel was plated with a white bronze bath at 1 A for 3 minutes. Throughout In the electroplating, all the baths appeared to be stable.

After plating, the panels were removed from the Hull cell, rinsed with DI water, and visually observed. As disclosed in Table 3 below, 1-(2-dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole and 3,6-dithia-1,8 are not included. The copper/tin/silver plating bath of the combination of octanediol exhibited undesired matte deposits at all current densities.

Although panels plated with formulations comprising a combination of tetrazole and octanediol have matte deposits at some higher current densities, most deposits are bright.

Example 4

Tetrazolium/thiodiethanol molar ratio in copper/tin plating bath

A white bronze copper/tin alloy plating bath was prepared as described in Example 2, but wherein the amount of thiodiethanol was varied as shown in Table 4 below. The molars of 1-(2-dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole to thiodiethanol are shown in Table 4.

A plurality of brass panels of dimensions 10 x 7.5 x 0.025 cm were degreased and activated as described in Example 2. The panels were then placed in separate Hull tanks containing a 250 mL white bronze bath. A platinized titanium or bronze electrode is used as the anode material. The working bath temperature is in the range of 30 ° C to 40 ° C. The panel was plated with a white bronze bath at 1 A for 3 minutes. All the baths appeared to be stable throughout the plating.

After plating, the panels were removed from the Hull cell, rinsed with DI water, and visually observed. Copper/tin plating not containing a combination of 1-(2-dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole and thiodiethanol as disclosed in Table 4 below The bath exhibited undesired matte deposits at all current densities. a panel plated with a bath containing a combination of 2.96 moles of 1-(2-dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole and thiodiethanol Bright deposits at lower current density ranges, and baths with a molar ratio of 1.14 have bright deposits at higher current densities, but baths with molar ratios below 1.14 are significant at all current densities Bright deposits.

Example 5 (comparative) Copper (II) bronze preparation

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

³ Adeka Tol PC-8: a nonionic surfactant available from Adeka Corporation.

The molar ratio of 1-(2-dimethylamino-ethyl)-5-mercapto-1,2,3,4-tetrazole to copper (II) ion is 0.15:1 in Comparative Bath 1, in It was 0.4:1 in the comparison bath 2 and 1.1:1 in the comparative bath 3.

A plurality of brass panels of size 10 x 7.5 x 0.025 cm were degreased and activated. The panels were then placed in a 250 mL three copper/tin plating bath. One of the separate Hull slots. The pH of the bath is less than 1. A platinized titanium or bronze electrode is used as the anode material. The working bath was maintained at 35 °C during plating. The panel was plated with a copper/tin bronze bath at 1 A for 3 minutes. After the panel was plated, it was rinsed with deionized water and its appearance was visually observed. The results for each bath are shown in Table 5a.

Although Baths 1 and 2 have good bright deposits at all current densities, Comparative Bath 3 has undesired yellow bronze deposits due to greater than 70% copper content and has very low current efficiency of less than 30%, such as thin Indicated by the sediment.

The comparison baths 1 and 2 were left unloaded for 24 hours. A new set of panels was then electroplated with comparative baths 1 and 2. Due to the poor results obtained by comparing bath 3, the plating performance was not tested for efficacy after 24 hours of dead time. The results of comparing Baths 1 and 2 are shown in Table 5b.

Matte bronze deposits plated after a 24 hour dead time indicated that the bath was unstable. The brightness is again established by adding an additional amount of tin (II) ions to the bath in an amount of one-half of the initial concentration; however, as indicated by the orange color of the bath, tin (II) is rapidly oxidized to tin (IV).

Example 6

Copper/tin/silver alloy composition of the Hull cell test

A 10 x 7.5 x 0.025 cm steel plate was immersed in a 40% hydrochloric acid solution for one minute to remove the protective zinc layer on the surface. The panel RONACLEAN ^TM DLF cleaning solution in the anodic degreasing 3ASD one minute. As described above in Example 1, by immersing the panels RONASALT ^TM 369 activated solution, rinsed with DI water, and placed in a bath containing 250ml of Hull cell white bronze. A platinized titanium electrode is used as the anode. The molar ratio of tetrazole to copper (I) ion in the bath was 1.2:1, and the molar ratio of tetrazole to 3,6-dithia-1,8-octanediol was 1.3:1.

The alloy composition was measured on a steel Hull cell plated at a current of 0.5 A for 5 minutes at different current densities as shown in Table 6 below. Use of the FISCHERSCOPEX ray model from Helmut Fischer AG with XRF XDV-SD measures the metal content. This measurement was repeated on three different steel plates coated with white bronze. The average metal content at each current density is shown in Table 6.

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

Example 7

Plating speed of copper (I) copper/tin/silver alloy plating bath compared to copper (II) copper/tin alloy plating bath

One liter of the white bronze bath of Example 1 was introduced into a glass tank. Place two platinum-plated titanium anodes in the bath. A cylindrical steel ring of 12 mm diameter and 7 mm height was mounted on the rotating shaft of the motor. The rotational speed of the shaft is fixed at 1000 rpm. The shaft is immersed in the bath and electrical contact is established between the electrodes. The current density was varied and the plating speed was measured for the new plating bath and for the same plating bath under different bath lifespans as shown in Table 7a. The thickness of the bronze coating was measured by using XRF measurements at each current density. The plating rate is calculated as the thickness of the plated white bronze in microns at each current density divided by the plating time in minutes. The results in microns per minute are presented in the table.

As indicated by the results in Table 7a, the plating rate increases with increasing current density and remains substantially the same regardless of bath life at each current density. This indicates that the electroplating bath is stable and its effectiveness is reliable when it ages. There is no need to dispose of the initial plating bath and use a new bath to complete the plating process.

The procedure was repeated using a copper (II) comparison bath in Table 7b below the bath life of 0 Ah/L and 10 Ah/L. The results are in Table 7c.

³ LUGALVAN® IZE (available from BASF)

⁴ PLURONIC® PE 6400 (available from BASF)

The plating rate is substantially constant with the bath life; however, it is lower at most current densities than the results in Table 7a. This display, The current efficiency of the copper (II) comparison bath was lower than that of the bath of Example 1.

Example 8

Current efficiency of copper/tin/silver alloy bath

The current efficiency of the white bronze electroplating bath of Example 1 was estimated as the experimental mass of the sediment divided by the theoretical mass multiplied by 100. The mass of the experiment was determined by measuring the difference in weight between the 5 x 7.5 x 0.025 cm brass panels before and after the white bronze plating. The theoretical mass of the sediment is calculated based on Faraday law and considering the alloy composition. This method is described in "Frederick Adolph Lowenheim, Electroplating (1978) p. 377; Library of Congress Cataloging, McGraw-Hill Book Company: ISBN 0-07-038836-9" .

The current efficiency was measured over a bath life of 0 Ah/L to 15 Ah/L at a high current density of 2 ASD. The CE% of Figure 1 provides multiple estimates of the life of the bath as shown in the bath life chart. The current efficiency is in the range of 90% to 100% with an average of about 95%. Values above 100% are due to possible experimental errors. The high and stable current efficiency over the life of the bath indicates an extremely stable electroplating bath in which the undesired hydrogen evolution is not significant.

Example 9

The ductility measurement of copper (I) copper/tin/silver bath compared to copper (II) copper/tin bath

Three 2×10×0.025 cm brass panels were plated with the white bronze electroplating bath of Example 1, and the other three were copper (II) copper/tin bronze alloys of Table 8 below. Bath plating. Add two liters of each bronze bath to a separate electrochemical cell. Two white bronze anodes were also placed in the tank. A current density of 1 ASD was applied between the anode and the brass cathode for 5 minutes to plate a 3 μm thick layer on each brass panel. For the formulations in Table 8, the plating time was 7 minutes. The deposit appears bright.

³ LUGALVAN® IZE (available from BASF)

⁴ PLURONIC® PE 6400 (available from BASF)

The ductility of each of the plated brass panels was tested according to ASTM Standard B 489-85 using a bend tester from SHEEN INSTRUMENTS Ltd. The average ductility of each of the three panels was determined. The average ductility of the white bronze of the bath of Example 1 was 1.2% elongation. Above this value, in deposition Cracks were observed in the material. For the deposits from the formulations in Table 8, cracks were observed at an elongation of 0.8%. When using the above instrument, 0.8% is the scale under the ductility test. The test was repeated, but the amount of white bronze plated on the brass panel was 6 μm. The average elongation of the bath from Example 1 was also 1.2%, and for the samples plated from the bath of Table 8, cracks were observed at 0.8%. The white bronze deposit from Example 1 exhibited improved ductility as compared to the bath liquid phase of Table 8.

Example 10

Thermal stability of white bronze

Six 2 x 10 x 0.025 cm brass panels were plated with the white bronze electroplating bath of Example 1, and the other three were plated with a copper (II) copper/tin bronze alloy bath from Table 8 of Example 9. Add two liters of each bronze bath to a separate electrochemical cell. Two white bronze anodes were also placed in the tank. A current density of 1 ASD was applied between the anode and the brass cathode for 4 minutes to plate a 3 μm thick layer on each brass panel. The two panel bath containing formulation of the example 1 and two plated table formulation of coating the plated panel 8 is introduced from the known conventional laboratory oven BINDER ^TM Company at 150 deg.] C for 24 hours. The remaining plated brass panels were left unannealed and kept at room temperature as a control. After 24 hours, the brass panels were removed from the oven and visually inspected along with the non-annealed panels. The panels plated with the white bronze bath of Example 1 and the panels maintained at room temperature were bright; however, the panels plated with the bath of Table 8 had an undesired blue appearance.

The test was repeated at 200 ° C for 2 hours. White bronze with example 1 The bath plate and the control panel are again bright. In contrast, the panels plated with the bath of Table 8 had an enhanced dark color. The white bronze electroplated from the bath of Example 1 exhibited improved heat resistance compared to the conventional bath of Table 8.

Example 11

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

Three 2 x 10 x 0.025 cm brass panels were plated with the white bronze electroplating bath of Example 1, and three additional copper (II) copper/tin bronze alloy baths of Example 9 were electroplated. Add two liters of each bronze bath to a separate electrochemical cell. Two white bronze anodes were also placed in the tank. A current density of 1 ASD was applied between the anode and the brass cathode for 5 minutes to plate a 3 μm thick layer on each brass panel. The deposit appears bright.

The commercially available from Dow Electronic Materials of RONAFLASH ^TM P gold plating bath in a separate electrochemical cell. The white bronze plated brass panels were rinsed with DI water and introduced into a gold bath. The panels are then plated with gold without any further surface treatment or preparation prior to gold plating. A current density of 1 ASD was applied between the bronze coated brass panel and the platinized titanium anode for 40 seconds. The panels were removed, rinsed with DI water, and dried with pressurized air. All deposits have a shiny golden appearance. Keep the panel open in the open air for one month at room temperature. The sample plated with the bath of Example 1 was still bright. In contrast, the panel plated with the bath of Example 9 appeared to be soiled with a number of dull areas on the surface.

The above described process is repeated, but instead of the gold plating on the panel, the panel using commercially available from Dow Electronic Materials CHROME GLEAM ^TM 3C of chromium (III) plated with chromium electroplating bath. The current density was 10 ASD and plating was carried out for 3 minutes. Bright chrome is deposited on the white bronze of each panel. Expose the panel to the open air at room temperature for one month. No stain was observed on the panel containing white bronze plated from the formulation of Example 1. Figure 2 is a photograph of one of the panels obtained with an OLYMPUS BX60M optical microscope. The chromium deposits are not stained. In contrast, the panels plated with the bath of Example 9 had unsightly stains. Figure 3 is a photograph of one of the panels plated with the bath of Example 9 obtained with an OLYMPUS BX60M optical microscope. Severe surface contamination of chromium deposits is evident. In contrast to the conventional bronze bath, the panel electroplated with the white bronze bath of Example 1 exhibited a significant improvement in stain resistance.

Claims (7)

An electroplating bath comprising one or more copper (I) ion sources, one or more alloy tin ion sources, optionally one or more alloy silver ion sources, one or more compounds having the formula: XSY (I) wherein X and Y may be the same or different and may be substituted or unsubstituted phenolic, HO-R- or -R'S-R"-OH, wherein R, R' and R" may be the same or different and have from 1 to 20 a linear or branched alkyl group of a carbon atom; and one or more tetrazole, wherein the one or more tetrazole in the electroplating bath is more than the molar ratio of the copper (I) ion 1. The one or more tetrazoles have a molar ratio of 0.05 to 4 to the one or more compounds of formula (I), and the electroplating bath is free of copper (II) ions and cyanide. An electroplating bath as claimed in claim 1, wherein X and Y are different and are HO-R- or -R'-S-R"-OH, and R, R' and R" may be the same or different. The electroplating bath of claim 1, wherein the one or more tetrazoles have the following formula: 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 group or substituted or unsubstituted (C ₆ -C ₁₀ ) aryl. An electroplating method comprising: a) contacting a substrate with an electroplating bath, the electroplating bath comprising one or more copper (I) ion sources, one or more alloy tin ion sources, optionally one or more alloy silver ion sources, one Or a plurality of compounds having the formula: XSY(I) wherein X and Y are the same or different and may be substituted or unsubstituted phenolic, HO-R- or -R'S-R"-OH, wherein R, R 'and R' may be the same or different and may be a straight or branched alkyl group having 1 to 20 carbon atoms; and one or more tetrazole, wherein the one or more tetrazole ratios in the electroplating bath The molar ratio of copper (I) ions And wherein said one or more tetrazole has a molar ratio of 0.05 to 4 to said one or more compounds of formula (I), said electroplating bath being free of copper ions (II) and cyanide; and b) The substrate is plated with a copper/tin alloy or, as the case may be, a copper/tin/silver alloy. The method of claim 4, wherein X and Y are different and are HO-R- or -R'-S-R"-OH, and R, R' and R" may be the same or different. The method of claim 4, wherein the one or more tetrazoles have the formula: 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 group or substituted or unsubstituted (C ₆ -C ₁₀ ) aryl. The method of claim 4, further comprising electroplating a finish layer of silver, gold, palladium or chromium on the copper/tin alloy or the copper/tin/silver alloy.