KR20010043710A - Electroplating baths - Google Patents

Abstract

The use of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts of alkyl and alkanol sulfonic acids as additives in many types of electroplating baths (ie, sulfates, sulfonic acids, fluoroborates, and halogen plating baths) has broader use. It has a number of unexpected advantages such as effective current density range, improved appearance, and improved oxidative stability.

Description

Electroplating Bath {ELECTROPLATING BATHS}

Electroplating solutions are generally water soluble. All plating solutions (1) provide an ion source of metal (s) to be deposited, (2) form a composite with ions of the deposited metal, (3) provide conductivity, (4) solution for hydrolysis or other decomposition processes At least one of: (5) buffering the pH of the solution, (6) controlling the physical formation of the deposits, (7) aiding anode corrosion, (8) modifying other unique properties for the contained solution, and Typically it contains ingredients that can perform several functions.

The present invention improves the plating properties of solutions, in particular by increasing the useful current densities for previously accepted standards. Current density is the area through which current passes, divided by the average current (amperes), where area is usually nominal because little pure area is known for very flat electrodes. The unit used in this regard is the square meter per ampere (A / m ² ).

It is of utmost concern to operate the plating bath efficiently at the highest current density possible. The higher the current density, the faster the coating plating on the surface. The electric current is carried by the ions in the plating bath, and each ion form has its own specific conductivity. In plating baths, however, ionic conductivity is one variable to consider when choosing an electrolyte. The ultimate property is the material of the coating at the desired current density.

Sulfate Plating Bath

Many metals and metal alloys are commercially plated from sulphate solutions as the main anion. See, for example, US Pat. Nos. 4,347,107, 4,331,518, and 3,616,306. Certain sulfate electroplating baths sometimes have limitations that can be alleviated by adding additives containing other anions. For example, the steel industry has produced tinned steel from sulfur / tin sulfate baths for many years, where phenolic sulfuric acid is used as a special electrolyte additive that not only improves the oxidation stability of tin but also increases the current density range of tin. This is known as the "ferrostan process", and due to the environmental problems with phenol derivatives, the steel industry seeks to replace them with plating baths which are harmless to the environment.

Similarly, nickel sulphate is used for nickel plating, but nickel chloride should also be provided to provide sufficient conductivity and improve anode dissolution. Such a plating bath is known as a Watts bath and, although economical, has many disadvantages such as high stress on the nickel plate.

Therefore, the present inventors have tried to find other additives that can improve the performance of the metal sulfate electroplating bath. There are many examples in the prior art in which surfactants and other organic additives are used to provide a more desirable finish. In the case of tin, the prior art also discloses additives that can improve the oxidation stability of tin to provide a plating bath with less sludge formation. It is not easy to find examples of additives that improve the plating range, especially at high current densities. Increasing the current density is a very desirable property, and it has been very difficult to find additives that can increase the current density without causing other problems in the plating bath.

Many plating baths are very sensitive to the presence of impurities, often when impurities are generated in the plating bath, the impurities adversely affect the material of the deposit. Therefore, these impurities must be removed or the plating bath must be replaced. For example, when tin plating steel, iron occurs in the plating bath, which iron eventually has to be removed because it adversely affects the material of the deposit. Thus, there is a great desire for additives to produce plating baths that are not sensitive to these impurities.

Sulfonic acid plating bath

In recent decades, the commercial use of sulfonic acid metal plating baths has increased significantly due to several performance advantages. See, for example, US Pat. Nos. 5,750,017, 4,849,059, 4,764,262, and 4,207,150. This increase has been markedly reduced in recent years as the price of alkyl-sulfonic acid has increased significantly. Although the prior art includes examples of other alkyl sulfonic acids and alkanol sulfonic acids, the preferred sulfonic acid is methane sulfonic acid (MSA). These other alkyl or alkanol sulfonic acids are more expensive than methane sulfonic acid and thus cannot compete with methane sulfonic acid.

Several manufacturers have produced large amounts of salts of 2-hydroethyl ethylsulfonic acid (isethionic acid), but the free acid form is not commonly used. These salts are significantly cheaper than methane sulfonic acid, but in recent plating techniques only the acid form of alkyl or alkanol sulfonic acids is used in the plating bath.

Advantages of alkyl sulfonic acid plating baths include low corrosion, high salt solubility, good conductivity, good tin salt oxidation stability, and complete biodegradability. The main plating metals in these sulfonic acid plating baths are tin, lead, copper, and alloys of these metals.

Fluoroborate Plating Bath

Fluoroborate plating baths are widely used to coat several metals on metal substituents including both copper and iron. See, for example, US Pat. Nos. 5,431,805, 4,029,556, and 3,770,599. These plating baths are preferred in the field where the plating speed is important and the fluoroborate is very water soluble. Several additives have been developed to improve the performance of these plating baths. These additives improve the material of the deposit, the efficiency of the plating bath, or the reduction of environmental pollution. See, for example, US Pat. No. 4,923,576.

Halogenated water plating bath

Plating baths in which halogenated ions (Br ⁻ , Cl ⁻ , F ⁻ , I ⁻ ) are the main electrolytes have been used for decades. For example, US Pat. Nos. 4,013,523, 4,053,374, 4,270,990, 4,560,446, and 4,612,091. The main halide ions in these plating baths were chloride and fluoride. Metals plated from these plating baths generally include tin, nickel, copper, zinc, cadmium, and alloys of these metals. With respect to all other types of plating baths, it has been found that the performance of the plating baths is improved by introducing additives into the plating baths. For example, US Pat. Nos. 5,628,893 and 5,538,617 disclose additives that can be used in halogen tin plating baths to reduce the formation of sludge by stabilizing tin against oxidation.

There are many other properties of the plating bath that can be improved by additives. All of these properties are basically related to the efficiency of the plating bath itself, the material of the deposit, or the reduction of environmental pollution. For example, the additives for tin plating baths disclosed in US Pat. Nos. 5,628,893 and 5,538,617 improve the efficiency of the plating bath and also reduce environmental pollution by reducing the amount of waste.

The present invention relates to an electroplating bath.

One embodiment of the present invention relates to the use of alkali metals, alkaline rare earth metals, ammonium-substituted alkali ammonium salts, and alkanol sulfonic acids that have been known to improve the performance of sulfate electroplating baths. When used in these electroplating baths, these salt additives have generally been found to improve the plating range so that the plating bath can be used at significantly higher current densities. Therefore, these plating baths can be plated at a much faster rate than the plating speed of the plating bath without the additive. In addition, the material of the deposit may be improved. In the case of tin sulfate plating solutions, an improvement in the oxidation stability of tin has also been observed.

Accordingly, a preferred embodiment of the present invention relates to a method for improving plating performance by adding effective performance enhancers such as salts of alkyl sulfonic acids and / or alkanol sulfonic acids to a water soluble sulfate based electroplating bath.

The salts used to improve the plating performance characteristics of the plating bath are especially selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. Particularly preferred salts are 2-hydroethyl ethyl sulfonates, in particular sodium salts (sodium isethionate).

Plating baths that can be improved by this embodiment include tin and tin alloy plating baths, nickel and nickel alloy plating baths, copper and copper alloy plating baths, chromium and chromium alloy plating baths, cadmium and cadmium alloy plating baths, and iron and iron. Alloy plating baths, rhodium and rhodium alloy plating baths, ruthenium and ruthenium alloy plating baths, and in particular iron / zinc and tin / zinc alloy plating baths.

Preferably, tin and tin alloy plating baths are improved by this embodiment of the present invention. Examples include tin-antimony, tin-cadmium, tin-copper, tin-lead, tin-nickel, tin-niobium, tin-titanium, tin-zirconium, and tin-antimony-copper alloy plating baths. Advantageously, the salts are selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts of 2-hydroethyl ethyl sulfonic acid (isethionic acid).

When used in electroplating baths such as MAS, these salt additives have generally been found to increase the plating range so that the plating bath can be used at much higher current densities. Therefore, these plating baths can achieve much faster plating speeds than the plating speed of the plating bath in which no additive is used. It has also been found that the material of the deposit is improved. In the case of tin alkyl sulfonate plating solutions, an improvement in the oxidation stability of tin has also been observed.

Another advantage is that these salts are harmless to the environment, these salts are completely biodegradable, and the biodegradable components are conventional iron and molecules found in the environment. In addition, these salts have many other advantages, including high solderability, low corrosiveness, high stability at high temperatures, and compatibility with many other metal salts.

In general, these salts also include the corresponding metal salts or metal salts where alloy plating is required, and will include various additives to control the material and appearance of the plating surface, and the stability of the plating solution. Typical additives include surfactants such as ethoxylate fatty alcohols, brighteners, if desired, and antioxidants such as hydroquinone or catechol when tin is one of the metals to be plated.

Tin in these salts is in stannous or reduced form. If oxidation occurs, the tin will be converted to a second tin or oxidized form which is then commonly precipitated to form sludge. This process increases the inefficiency of the salts and requires constant filtering. Prior art patents, such as US Pat. Nos. 4,717,460 and 5,562,814, disclose components that can reduce the amount of oxidized tin.

Another advantage when using salts of alkyl sulfonic acids or alkanol sulfonic acids is that they are much cheaper than the corresponding other acids. Recently, alkyl / alkanol sulfonic acids suitable for electroplating are methane sulfonic acids and salts of alkali / alkaline rare earth / ammonium alkyl / alkanol sulfonic acids suitable for electroplating are sodium isethionate. When comparing the prices of these two commercial components, sodium isethionate is less than half the price of methane sulfonic acid based on molar or weight.

Another embodiment of the invention relates to the use of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts of alkyl sulfonic acids and alkanol sulfonic acids found to improve the performance of fluoroborate electroplating baths. When they are used in electroplating baths, these salts generally increase the plating range so that the electroplating bath can be used at much higher current densities, so these plating baths are much faster than plating rates when these additives are not used. Has a plating rate. In addition, the use of these salts improves the material of the deposit.

Thus, this embodiment of the present invention relates to a method for improving plating performance by adding effective performance enhancers, such as salts of alkyl sulfonic acids and / or alkanol sulfonic acids, to a fluoroborate based electroplating bath.

The salts used to improve the plating performance characteristics of the plating bath are especially selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. Particularly preferred salts are 2-hydroethyl ethyl sulfonate and sodium salt (sodium isethionate).

Plating baths that can be improved by this embodiment include tin and tin alloy plating baths, nickel and nickel alloy plating baths, copper and copper alloy plating baths, zinc or zinc alloy plating baths, as well as cadmium and cadmium alloy plating baths. do.

Another embodiment of the invention relates to the use of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts of alkyl sulfonic acids and alkanol sulfonic acids that have been found to improve the performance of halogenated electroplating baths. When they are used in electroplating baths, these salt additives generally increase the electroplating range and find that the electroplating bath can be used at much higher current densities than before. These plating baths can achieve plating rates much faster than those of plating baths without these additives. It also improves the material of the deposit.

Thus, this embodiment of the present invention relates to a method for improving plating performance by adding effective performance enhancers such as salts of alkyl sulfonic acids and / or alkanol sulfonic acids to a halogenated ion based electroplating bath. In a preferred embodiment, the halide ions of the plating bath are generally chlorides or fluorides.

The salts used to improve the plating performance characteristics of the electroplating bath are in particular selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. Particularly preferred salts are 2-hydroethyl ethyl sulfonates, in particular sodium salts (sodium isethionate).

Plating baths that can be improved by this embodiment include tin and tin alloy plating baths, nickel and nickel alloy plating baths, copper and copper alloy plating baths, zinc or zinc alloy plating baths, as well as cadmium and cadmium alloy plating baths. do.

The use of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts of alkyl and alkanol sulfonic acids as additives in pure metal and metal alloy sulfate electroplating baths has a broader effective current density range, improved appearance, and improved appearance. It has a number of unexpected advantages such as oxidative stability. These plating baths can plate much faster than plating baths without additives. In addition, the material of the deposit can be improved, and the durability against impurities such as iron can also be improved. In the case of the stannous sulfate plating solution, the oxidation stability of tin was also improved.

Unlike phenol sulfonic acids, these salts are harmless to the environment. These salts are completely biodegradable, and the biodegradable components are common iron and molecules found in the environment. In addition, these salts have many other advantages, including high solderability, low corrosiveness, high stability at high temperatures, and compatibility with many other metal salts.

In general, these salts also include the corresponding metal salts or metal salts where alloy plating is required, and will include various additives to control the material and appearance of the plating surface, and the stability of the plating solution. Typical additives include surfactants such as ethoxylate fatty alcohols, brighteners, if desired, and antioxidants such as hydroquinone or catechol when tin is one of the metals to be plated.

Tin in these salts is in stannous or reduced form. If oxidation occurs, the tin will be converted to a second tin or oxidized form which is then commonly precipitated to form sludge. This process increases the inefficiency of the salts and requires constant filtering. Prior art patents, such as US Pat. Nos. 4,717,460 and 5,562,814, disclose components that can reduce the amount of oxidized tin.

The present invention will be described in more detail below with reference to the following examples for better understanding of the present invention. However, the present invention is not limited to these embodiments. All percentage units described herein are by weight unless otherwise indicated. All temperature units are ° C.

Sulfate Plating Bath

Example 1

The experimental plating bath was evaluated on hull cells hydrodynamically controlled for 1 minute plating time at up to 30 amps. Plating strips were made of steel and pretreated by soaking in alkaline baths for 15 seconds and then immersing in 10% sulfate for 15 seconds and then washing again. The next plating bath with various levels of sodium isethionate added was evaluated.

Plating bath composition:

5% sulfuric acid

20.0 g / l Sn (First Tin Sulphate)

3 g / ℓ JWL 5000 surfactant

0.1 g / l salicylic acid

5 ppm 2.9-dimethyl-phenanthtoline

number Additives and levels Plating test result One No additives Black flame against high current density edge of 5 amps. The flame has a width of 12 mm at a high current density edge of 10 amps 2 10 g / l sodium isethionate (calculated as isethionic acid) Glossy deposit of very light gray at 10 amps-no flame 3 20 g / l sodium isethionate (calculated as isethionic acid) Glossy deposit of very light gray at 30 amps-no flame 4 1 g / l sodium sulfate 12 mm wide spark formation at high current density edges of 10 amps 5 30 g / l sodium sulfate 4 mm wide spark formation at high current density edges of 40 amps

These results show that the current density range is significantly increased by adding sodium isethionate to the sulfate plating bath. The 15 amp panel shows a current density at 600 amps / ft ² and the 30 amp range is equivalent to 1200 amps / ft ² . These results also show that sodium ions can have a positive effect on increasing the current density range, but sodium alkanol sulfate has a significant effect.

Example 2

The same plating bath and procedure as in Example 1 were used, but in this example sodium methyl sulfonate was used as an additive and a current of up to 10 amperes was used.

number Additives and levels Plating test result One No additives Black flame against high current density edge of 5 amps 2 10 g / l sodium methane sulfonate (calculated as methane sulfonic acid) Slightly reflective glossy deposits of very light gray at 10 amps-no flame 3 20 g / l sodium methane sulfonate (calculated as methane sulfonic acid) Light gray glittery deposit from 10 amperes to high current density-no flame

These results show that the current density range is significantly increased by adding sodium methane sulfonate to the sulfate plating bath.

Example 3

The following experiment shows the inhibitory effect of hydrosyl alkyl sulfonate in stannous sulfate / sulphate aqueous solution. The effect of iron for the stabilization of stannous ions against oxidation is disclosed in No. 3 in comparison with others. Oxygen was bubbled through 150 ml of the following solution at 120 ° F. for 64 hours.

number SnSO ₄ Sn ²⁺ g / ℓ FeSO ₄ Fe ²⁺ g / ℓ H ₂ SO ₄ g / ℓ NaO ₃ SCH ₂ CH ₂ OH Reduction of Sn ²⁺ concentration g / ℓ One 23 10 10 0 10.3 2 23 10 10 30 8.6 3 23 0 60 30 23 4 23 10 60 30 4.0 5 23 10 80 0 3.2 6 23 10 80 30 0.2

Sulfonic acid plating bath

Almost no salts of alkali / alkaline rare earth / ammonium alkyl / alkanol sulfonic acids have been previously used in electroplating, where they are first converted to acids. The present invention relates to the use of these salts in electroplating. The use of such salts makes it possible to use inexpensive manufacturing techniques such as the Steckler process to make these salts. For example, CH ₃ Cl + Na ₂ SO ₃ → CH ₃ SO ₃ Na + NaCl. In this reaction, sodium chloride can be crystallized and the resulting sodium methane sulfonate can then be used in an electroplating bath.

Lowering free acid levels and preparing sodium isethionate additives

Plating tests confirmed that the addition of sodium isethionate in known MSA tin / lead systems could reduce the amount of methane sulfonic acid required in the plating bath. The reduction of methane sulfonic acid in MSA due to the addition of sodium isethionate optimizes plating performance by reducing the cost and improving the overall gloss of tin or tin / lead deposits. Plating tests were performed with the acid reduced to one third and without adverse effects. Some plating tests showed that addition of sodium isethionate significantly improved the overall deposit. The reduction of sparks and bands improved the upper current density range. Commercially useful plating systems (trade name Tech MSA 90/10 manufactured by Tech Incorporated) have increased from 120 ASF to a current density range greater than 240 ASF.

The overall advantage of the addition of sodium isethionate varies from plating system to plating system, but the reduction in total anhydrous rate by up to 2/3 (66%) by addition of sodium isethionate is acceptable in the following examples. Figured out.

Typical commercial MSA plating systems include approximately 15% v / v MSA. The following results reflect the plating test performed with two plating baths made of two different levels of MSA. The first plating bath, namely Example 4 and Example 5, was made with 15% v / v MSA and Example 6 and Example 7 were made with 15% v / v MSA.

Plating performance tests were performed using HCHC (hydrodynamically controlled hull cells). Due to the increased agitation for typical hull cell configurations, the overall advantage in the top current density can be confirmed by the addition of sodium isethionate. The result is the width of the flame and the band in mm, if applicable. Both the flame and the band in the HCD to MCD regions affect the overall operable current density range of the plating bath. The current density regions disclosed in the final column of the result table represent the current density ranges for optimal deposition. The addition of sodium isethionate to the plating bath reduces or eliminates flames and bands, and extends the optimum current density range.

Plating tests performed at 5% v / v MSA did not have any band in the HCD region. However, the maximum amperage attainable at 5% v / v MSA was 10 amps. The addition of 15 g / l sodium isethionate to the system containing only 5% v / v MSA allowed application of up to 20 amps. The result table is as follows.

Plating bath solution:

15% v / v MSA

15 g / l Sn (TiN methane sulfonate)

12 g / L TECHNI Tin / Lead Salt # 2 (Technic Incorporated)

5% v / v TECHNI 800 HS Makeup (Technic Incorporated)

1% v / v TECHNI 800 HS Second "A" (Technic Incorporated)

Plating conditions: 10 amps, 1 minute, 1500 rpm, 110 ° F. An increase in amperage was performed for the plating system under these plating conditions.

Example 4 shows the result of the plating bath described above without adding sodium isethionate.

Example 5 shows the results of the plating bath described above under the same plating conditions to which 15 g / L sodium isethionate was added.

Example 4

Amperage additive Sparkle / mm Band in mm / mm Current density range 10 amps, 1 minute none 3 mm 10 mm 400-1 ASF 15 amps, 1 minute none 15 mm 15 mm 400-1 ASF 20 amps, 1 minute none 60 mm 5 mm 200-1 ASF

Example 5

Amperage additive Sparkle / mm Band in mm / mm Current density range 10 amps, 1 minute 15 g / l sodium isethionate 2 mm none +400-1 ASF 15 amps, 1 minute 15 g / l sodium isethionate 7 mm none +600 ASF-LCD Edge 20 amps, 1 minute 15 g / l sodium isethionate 7 mm none +800 ASF-LCD Edge

Plating bath solution:

15% v / v MSA

15 g / l Sn (TiN methane sulfonate)

12 g / L TECHNI Tin / Lead Salt # 2 (Technic Incorporated)

5% v / v TECHNI 800 HS Makeup (Technic Incorporated)

1% v / v TECHNI 800 HS Second "A" (Technic Incorporated)

Plating conditions: 10 amps, 1 minute, 1500 rpm, 110 ° F. An increase in amperage was performed for the plating system under these plating conditions.

Example 6 shows the results of the plating bath described above without adding sodium isethionate. Example 7 shows the results of the plating bath described above under the same plating conditions to which 15 g / L sodium isethionate was added.

Using the hull cell specification, the current density range of the 10 amp panel looks similar. However, early panels without sodium isethionate have treeing along the panel edges. Goals are not visible in panels with sodium isethionate added. In practical applications, the presence of the valleys narrows the operating range of the plating bath.

Example 6

Amperage additive Sparkle / mm Band in mm / mm Current density range 10 amps, 1 minute none 3mm, goal along HCD edge none +400-60 ASF 15 amps, 1 minute none Can't achieve 15 amps, up to 10 amps 20 amps, 1 minute none Can't achieve 20 amps, up to 10 amps

Example 7

Amperage additive Sparkle / mm Band in mm / mm Current density range 10 amps, 1 minute 15 g / l sodium isethionate 2mm, no bone none +400-60 ASF 15 amps, 1 minute 15 g / l sodium isethionate 2mm, no bone none +600-LCD 20 amps, 1 minute 15 g / l sodium isethionate 10mm, no bone none +800-LCD

Different sodium sources were added to pure tin MSA and banding was significantly reduced or completely removed. The change in banding significantly extended the current density range while opening the operating window of the system.

Plating bath composition:

10% v / v MSA

15 g / l Sn (TiN methane sulfonate)

0.1 g / l salicylic acid

0.3 g / L Zepos WPS 5000 (Jeffox WL 5000) [Huntsman]

5 ppm 2,9-dimethyl-1,10-phenanthroline

Plating conditions: HCHC, 10 amps, 1 minute, 1500 rpm, 100 ° F.

Example 8

additive Sparkle / mm Band in mm / mm Current density range none 5 mm 25 mm 400-200 ASF 1 g / L Sodium Methane Sulfonate 5 mm 25 mm 400-200 ASF 10 g / l sodium methane sulfonate 5 mm 25 mm 400-200 ASF 20 g / l sodium methane sulfonate 5 mm 25 mm 400-60 ASF

The same MSA tin plating bath was prepared in the same manner as described above, and sodium isotinate was added. Plating conditions: HCHC, 10 amps, 1 minute, 1500 rpm, 100 ° F.

Example 9

additive Sparkle / mm Band in mm / mm Current density range none 5 mm 25 mm 400-200 ASF 5 g / l sodium isothionate 2.5mm 20 mm 400-200 ASF 10 g / l sodium isothionate 2.5mm none 400-20 ASF

Looking at the current density range, the addition of sodium methane sulfonate and sodium isethionate both appear to have similar advantages. However, the addition of sodium isethionate is preferred because sodium isethionate minimizes flame compared to sodium methane sulfonate. In fact, it will have a wider working window. In addition, sodium isethionate brightens all deposits uniformly over the entire current density range.

Example 10

This example illustrates the ability of alkanol sulfonates to prevent oxidation of stannous ions in methane sulfonate based on tin plating bath solutions.

Air was bubbled through the next solution of 100 ml at a rate of 100 ml / min for 288 hours at room temperature.

number Sn (O ₃ SCH ₃ ) ₂ Sn ²⁺ g / ℓ FeSO ₄ Fe ²⁺ g / ℓ NaO ₃ S (CH ₂ ) ₂ OHg / ℓ HO ₃ SCH ₃ g / ℓ Reduction of Sn ²⁺ concentration g / ℓ One 23 10 10 0 10.3 2 23 10 10 30 8.6 3 23 0 60 30 23 4 23 10 60 30 4.0

The use of substituted ammonium salts of alkali metals, alkaline rare earth metals, ammonium, and alkyl sulfonic acids and alkanol sulfonic acids as additives in pure metal and metal alloy fluoroborate electroplating baths has a broader effective current density range and improved appearance. It has a number of unexpected advantages, including. Metals and metal alloys include, but are not limited to, tin, lead, copper, cadmium, indium, iron, tin / lead, and tin / lead copper.

Fluoroborate Plating Bath

Example 11

A standard hull cell test using a 267 mm hull cell was performed at 2 amps for 5 minutes using negative rod stirring. The copper panels were plated after pickling and rinsing.

Plating bath composition:

35% v / v HBF ₄ (for 50% solution)

15 g / l tin (tin fluoroborate)

12 g / l lead (lead fluoroborate)

2 g / l hydrohydroquinone

26 g / l boric acid

2% v / v HBF ₄ Makeup

number additive result One none Gray matte deposit with 5 mm wide flame at high current density edges 2 20 g / l sodium methane sulfonate Deposition is bright and flame narrows to 4mm wide 3 20 g / l sodium isethionate Deposition is bright and flame narrows to 3.5mm wide

This embodiment can be used at high current densities when adding sodium methane sulfonate or sodium isethionate, and the appearance of the coating expands.

Halogen Plating Bath

The use of substituted ammonium salts of alkali metals, alkaline rare earth metals, ammonium, and alkyl sulfonic acids and alkanol sulfonic acids as additives in pure metal and metal alloy halide electroplating baths covers a wider effective current density range and improved appearance. There are a number of unexpected advantages. Metals and metal alloys include, but are not limited to, tin, lead, copper, nickel, zinc, cadmium, tin / zinc, zinc / nickel, and tin / nickel.

Halogen-based plating baths were performed on HCHC or hydrodynamically controlled hull cells. The plating strips were made of steel and pretreated by soaking in 15 seconds in alkali and washing, then 15 seconds in 10% sulfonic acid and washing again.

The following plating baths with various levels of sodium isethionate added were evaluated.

Plating bath composition (room temperature):

16.9 g / ℓ NaHF ₂

26.5 g / ℓ NaF

12.68 g / l NaCl

33.0 g / ℓ SnF ₂

* 4 g / l Miranol ASC (positive surfactant)

number Current / time additive result One 2 amps / 2 minutes none Dendritic growth 2 mm wide at high current density edges, white matte / satin color with rest 2 3 amps / 2 minutes none Fierce sparks 6 mm wide at high current density edges. Same color as number 1 3 3 amps / 2 minutes 4 g / l sodium isethionate The flame does not occur and narrows to about 3mm. Uniform and smooth matte finish 4 3 amps / 2 minutes 6 g / l sodium isethionate Reduced sparking only at high current density edges. Uniform and smooth matte finish equal to number 3

This example shows that the addition of a very small amount of sodium isethionate to the halogenated plating bath can increase the operable current density range by up to 50%.

Theory part

Without being bound by theory, it is believed that the results of the present invention are based on the following description.

Mixtures of different ionic species form a unique mixture from which metal coatings with the required properties can be made. The overall ionic conductivity of the solution depends on the nature and concentration of each of the ions. It is well known that particular interactions between different ionic species and / or solvent molecules determine the overall conductivity and may affect the electrodeposition process. However, ionic conductivity is only one variable that should be considered to formulate the plating bath.

In addition, the structure of the electrical double layer can affect the deposition rate. "Journal of Electroanalytical Chemistry," published in 1989 by Lasia et al., Pp. 266 68-81; "Journal of Electroanalytical Chemistry," published in 1990 by Fawcett et al., Pages 279 to 243-256; "Journal of Electroanalytical Chemistry," published by Lacia et al, 1990, pp. 288-153; Referring to "Journal of Electroanalytical Chemistry," published in 1997 by Balch et al., Pp. 427-137, certain quaternary ions (Cu ⁺ , Cd ²⁺ , or Zn ^{2). It} has been experimentally demonstrated that the electroreduction constant (such as ⁺ ) depends on the solvation capacity of the solvent and the size of the cation of the electrolyte. This effect contributed to the electrostatic interaction in the inner layer of the electrical bilayer.

According to the Prumkin model, the rate constant for the reduction process Met ^{n +} + ne → Met ^O is: ln k _f = ln (k _O Υ _M ) + α _a nFΦ ^d / RT-α _a nF (EE _s ) / RT, where k _f is the apparent rate constant, k _O is the potential of the independent portion of the rate constant, Υ _M is the activation coefficient of the species Met ^{n + in} the bulk solution, and α _a is the apparent transfer coefficient for reduction , n is the number of electrons involved in the electroreduction, F is the Faraday constant, Φ ^d is the potential drop across the diffusion layer, R is the gas constant, T is the temperature (K), E is the potential, and E _s is the standard of the electroreduction reaction. Potential.

The size of the counter ions supporting the electrolyte affects the potential Φ ^d and ultimately affects the rate constants of the overall electroreduction process (see Lasia, Faucet, and Lasia's, above).

It is evident that the addition of one or more salts as disclosed herein will modify the interface of the metal / solution of the bilayer. Such modifications are caused by alkali metal cations and / or alkanol-sulfonic acid anions and / or combinations thereof (possibly alkyl-). Thus, salts of added alkyl and / or alkanol sulfonic acids should be considered as plating additives rather than as simple modifications of the supporting electrolyte.

In the present invention, the cations and / or anions are not added only to maintain the ion conductivity of the electrolyte and / or the water solubility of the deposited ions, but instead they directly affect the electrodeposition process by affecting the bilayer structure and ultimately This affects the mechanism of the electroreduction process.

The present invention has been described in detail through the preferred embodiment. However, those skilled in the art will understand that variations and / or modifications may be made within the spirit and scope of the invention as claimed in the following claims.

Claims (74)

In the method of improving the plating performance of a water-soluble electroplating bath selected from the group consisting of sulfate, sulfonic acid, fluoroborate, and halogen electroplating bath, Adding an amount of alkyl and / or alkanol sulfonic acid salt to the electroplating bath that can effectively enhance performance. The method of claim 1 wherein the salt is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. The method of claim 2 wherein the salt is a salt of 2-hydroxy ethyl sulfonic acid. 4. The method of claim 3 wherein the salt is sodium isethionate. The method according to any one of claims 1 to 4, wherein the electroplating bath is a sulfate electroplating bath. The method according to any one of claims 1 to 4, wherein the electroplating bath is a sulfonic acid electroplating bath. The method according to any one of claims 1 to 4, wherein the electroplating bath is a fluoroborate electroplating bath. The method according to any one of claims 1 to 4, wherein the electroplating bath is a halogen electroplating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is a tin or tin alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is a nickel or nickel alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is a copper or copper alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is a chromium or chromium alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is iron or an iron alloy plating bath. 9. The method according to any one of claims 1 to 8, wherein the electroplating bath is a rhodium or rhodium alloy plating bath. The method according to any one of claims 1 to 8, wherein the electroplating bath is a ruthenium or ruthenium alloy plating bath. 9. The method of any one of claims 1 to 8, wherein the electroplating bath is an iron / zinc plating bath. 9. A method according to any one of the preceding claims, wherein the electroplating bath is a tin / zinc plating bath. 9. A method according to any one of the preceding claims, wherein the improvement in plating performance comprises at least an increase in the effective upper current density range of electroplating. In the water-soluble metal alloy sulfate electroplating bath, Sulfate anionic source, At least one soluble metal salt, wherein the metal is selected from the group consisting of tin, nickel, copper, chromium, cadmium, iron, rhodium, ruthenium, zinc, and mixtures thereof, and An electroplating bath comprising salts of alkyl and / or alkanol sulfonic acids. 21. The electroplating bath of claim 20, wherein said sulfonate is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 22. The electroplating bath of claim 21, wherein the sulfonate salt is a salt of 2-hydroxy ethyl sulfonic acid. 23. The electroplating bath of claim 22, wherein said salt is sodium isethionate. In the method for improving the plating performance of sulfonic acid based electroplating bath, Replacing at least a portion of the alkyl sulfonic acid electrolyte with salts of alkyl and / or alkanol sulfonic acids. 25. The method of claim 24, wherein the salt is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 26. The method of claim 24 or 25, wherein the sulfonic acid is alkyl sulfonic acid. 27. The method of claim 26, wherein said alkyl sulfonic acid is methane sulfonic acid. 26. The method of claim 24 or 25, wherein the salt is 2-hydroxy ethyl sulfonic acid. 26. The method of claim 24 or 25, wherein the electroplating bath is a tin electroplating bath. 26. The method of claim 24 or 25, wherein the electroplating bath is a lead electroplating bath. 26. The method of claim 24 or 25, wherein the electroplating bath is a tin / lead electroplating bath. A method in which tin plating can be performed at high speed by increasing the effective upper current density range of a methane sulfonate electroplating bath, Adding an effective amount of sodium or potassium methane sulfonate to the plating bath. A method in which tin plating can be performed at high speed by increasing the effective upper current density range of a methane sulfonate electroplating bath, Replacing at least a portion of the methane sulfonic acid with sodium isethionate. 34. The method of claim 33, wherein up to 50% of the methane sulfonic acid is replaced with sodium isethionate. 34. The method of claim 33, wherein up to 75% of the methane sulfonic acid is replaced with sodium isethionate. 34. The method of claim 33, wherein up to 90% of the methane sulfonic acid is replaced with sodium isethionate. A method of preventing oxidation of stannous ions in a tin plating bath containing methane sulfonic acid, Adding an effective amount of a salt of alkyl and / or alkanol sulfonic acid. 38. The method of claim 37, wherein said salt is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. In the water-soluble metal alloy sulfonic acid electroplating bath, (a) alkyl or alkanol sulfonic acids, (b) at least one soluble metal salt, wherein the metal is a soluble metal salt selected from the group consisting of tin, lead, copper, cadmium, indium, iron, and mixtures thereof, and (c) an electroplating bath comprising salts of alkyl and / or alkanol sulfonic acids. 40. The electroplating bath of claim 39, wherein said sulfonate is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 41. The electroplating bath of claim 40, wherein said sulfonate salt is a salt of 2-hydroxy ethyl sulfonic acid. 42. The electroplating bath of claim 41, wherein the sulfonate is sodium isethionate. A method for improving the plating performance of a water soluble fluoroborate based electroplating bath, Adding an amount of alkyl and / or alkanol sulfonic acid salt to the electroplating bath that can effectively enhance performance. 44. The method of claim 43, wherein said salt is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 45. The method of claim 44, wherein said salt is a salt of 2-hydroxy ethyl sulfonic acid. 46. The method of claim 45, wherein said salt is sodium isethionate. 47. The method of any of claims 43-46, wherein the electroplating bath is a tin or tin alloy plating bath. 47. The method of any of claims 43-46, wherein the electroplating bath is a lead or lead alloy plating bath. 47. The method of any of claims 43 to 46, wherein the electroplating bath is a copper or copper alloy plating bath. 47. The method of any one of claims 43 to 46, wherein the electroplating bath is an indium or indium alloy plating bath. 47. The method of any of claims 43 to 46, wherein the electroplating bath is an iron or iron alloy plating bath. 47. The method of any one of claims 43 to 46, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. 47. The method of any of claims 43-46, wherein the electroplating bath is a tin / lead plating bath. 47. The method of any of claims 43-46, wherein the electroplating bath is a tin / lead / copper plating bath. 44. The method of claim 43, wherein the improvement in plating performance comprises at least an increase in the effective upper current density range of electroplating. In the water-soluble metal alloy fluoroborate electroplating bath, (a) a fluoroborate ion source, (b) at least one soluble metal salt, wherein the metal is a soluble metal salt selected from the group consisting of tin, lead, copper, cadmium, indium, iron, and mixtures thereof, and (c) an electroplating bath comprising salts of alkyl and / or alkanol sulfonic acids. 59. The electroplating bath of claim 56, wherein the sulfonate is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 59. The electroplating bath of claim 57, wherein said sulfonate salt is a salt of 2-hydroxy ethyl sulfonic acid. 59. The electroplating bath of claim 58, wherein said sulfonate is sodium isethionate. A method for improving the plating performance of a water-soluble halogen ion based electroplating bath, Adding an amount of alkyl and / or alkanol sulfonic acid salt to the electroplating bath that can effectively enhance performance. 61. The method of claim 60, wherein the halogen ions are selected from chlorides and fluorides. 61. The method of claim 60, wherein said salt is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 63. The method of claim 62, wherein the salt is a salt of 2-hydroxy ethyl sulfonic acid. 64. The method of claim 63, wherein said salt is sodium isethionate. 65. The method of any of claims 60 to 64, wherein the electroplating bath is a tin or tin alloy plating bath. 65. The method of any of claims 60 to 64, wherein the electroplating bath is a nickel or nickel alloy plating bath. 65. The method of any of claims 60 to 64, wherein the electroplating bath is a copper or copper alloy plating bath. 65. The method of any of claims 60 to 64, wherein the electroplating bath is a zinc or zinc alloy plating bath. 65. The method of any of claims 60 to 64, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. 61. The method of claim 60, wherein the improvement in plating performance comprises at least an increase in the effective upper current density range of electroplating. In the water-soluble metal alloy fluoroborate electroplating bath, (a) a halogen anion source, (b) at least one soluble metal salt, wherein the metal is a soluble metal salt selected from the group consisting of tin, nickel, copper, zinc, cadmium, and mixtures thereof, and (c) an electroplating bath comprising salts of alkyl and / or alkanol sulfonic acids. 72. The electroplating bath of claim 71, wherein the sulfonate is selected from the group consisting of alkali metals, alkaline rare earth metals, ammonium, and substituted ammonium salts. 73. The electroplating bath of claim 72, wherein said sulfonate salt is a salt of 2-hydroxy ethyl sulfonic acid. 74. The electroplating bath of claim 73, wherein said salt is sodium isethionate.