KR100840451B1 - An aqueous electroplating bath, a method of manufacturing an aqueous electroplating bath and a method of electroplating using the bath - Google Patents

Abstract

The use of alkali metal salts, alkaline earth metal salts of alkyl and alkanol sulfonic acids, and ammonium salts or substituted ammonium salts as additives in many forms of electroplating baths (ie sulfate, sulfonic acid, fluoroborate, and halide plating baths) It has a number of unexpected advantages such as effective current density range, improved appearance, and improved oxidative stability.

Description

Aqueous electroplating bath, a method for producing an aqueous electroplating bath, and a plating method using the aqueous electroplating bath TECHNICAL FIELD

The present invention relates to an electroplating bath.

Electroplating solutions are generally aqueous. All plating solutions (1) provide an ion source of metal (s) to be deposited, (2) complex with ions of the attached metal, (3) provide conductivity, (4) hydrolysis or other decomposition processes At least among the functions of stabilizing the solution, (5) buffering the pH of the solution, (6) adjusting the physical form of the deposit, (7) aiding anode corrosion, and (8) modifying other unique properties for the solution involved. It includes ingredients that can perform one and typically several functions.

The present invention improves the plating properties of the solution, in particular by increasing the effective current density compared to previously accepted standards. The current density is the average current (amps) divided by the area through which the current passes, where area is the nominal area, because it is difficult to know the true area even for extremely flat electrodes. The unit used in this regard is amperes per square meter (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. Current is carried by the ions in the plating bath, and each type of ions has its own specific conductivity. In plating baths, however, ionic conductivity is only one of the variables to be considered when selecting an electrolyte. The final criterion is the quality of the coating at the desired current density.

Sulfate Plating Bath

Many metals and metal alloys are commercially plated from solutions with sulfates as the main anion. See, for example, US Pat. Nos. 4,347,107, 4,331,518, and 3,616,306. Certain sulfate electroplating baths have several limitations, which can sometimes be mitigated by adding additives containing other anions. For example, the steel industry has been manufacturing tin-plated steel from sulfuric acid / tin sulfate baths for many years, where phenolic sulfuric acid not only improves the oxidation stability of tin but also increases the tin current range. Used as electrolyte additive. 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 sulfate 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 nickel plate being subjected to high stress.

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 higher current densities. Increasing the current density is a very desirable property, but it was very difficult to find an additive 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 quality of the deposit. Therefore, these impurities must be removed or the plating bath must be replaced. For example, in tin plated steel, iron occurs in the plating bath, which iron eventually has to be removed because it adversely affects the quality of the deposit. Thus, there is a great desire for additives that make the plating bath insensitive 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 and alkanol sulfonic acids, methane sulfonic acid (MSA) has been used as the preferred sulfonic acid. 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 metals to be plated in these sulfonic acid plating baths are tin, lead, and copper as well as alloys of these metals.

Fluoride Borate Plating Bath

Fluoroborate plating baths are widely used to coat several metals on all types of 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 preferable when the plating speed is important and the solubility of the fluoroborate is high. Several additives have been developed to improve the performance of these plating baths. These additives improve the quality of the deposit, the efficiency of the plating bath, or reduce environmental pollution. See, eg, US Pat. No. 4,923,576.

Halide plating bath

Plating baths in which halide ions (Br ⁻ , Cl ⁻ , F ⁻ , I ⁻ ) are the main electrolytes have been used for decades. See, 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 chlorides and fluorides. Metals plated from these plating baths generally include tin, nickel, copper, zinc, cadmium, and alloys of these metals. As with 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 halide 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 quality 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.

One embodiment of the present invention relates to the use of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts of alkyl and alkanol sulfonic acids, which have been found to improve the performance of sulfate electroplating baths. When used in these electroplating baths, it has been found that these salt additives generally increase 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 these additives. In addition, the quality of the deposit can be improved. In the case of tin sulfate plating solutions, an improvement in the oxidation stability of tin has also been observed.

Thus, a preferred embodiment of the present invention is a plating of an aqueous sulphate based electroplating bath comprising the step of adding an amount of alkyl and / or alkanol sulfonic acid salt to the aqueous sulphate based electroplating bath that can effectively enhance performance. A method for improving performance.

The salts used to improve the plating performance properties of the plating bath are in particular selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts. Particularly preferred salts are 2-hydroxy 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. Alloying compositions containing these metals are known to those of ordinary skill in the art, and these alloying compositions are claimed by many patents.
Another preferred embodiment of the present invention relates to the use of salts of alkyl and alkanol sulfonic acids, which have been found to improve the performance of sulfonic acids, in particular alkyl sulfonic acid electroplating baths. Advantageously, the salts are selected from the group consisting of substituted ammonium salts, ammonium salts, alkali metal salts, alkaline earth metal salts of 2-hydroxy ethyl sulfonic acid (isethionic acid).

When used in electroplating baths such as MSA, it has been found that these salt additives generally increase the plating range so that the plating bath can be used at much higher current densities. Therefore, these plating baths can achieve plating rates much faster than those of plating baths in which these additives are not used. It has also been found that the quality 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, and these salts are completely biodegradable, and the biodegradable components are conventional ions and molecules found in the environment. In addition, these salts have many other advantages, including high solderability, low corrosiveness to equipment, high stability at high temperatures, and compatibility with many other metal salts.

In addition, these plating baths will generally include corresponding metal salts or metal salts where alloy plating is required, and will include various additives to control the quality 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 plating baths is in stannous or reduced form. If oxidation occurs, tin is converted to stannic or oxidized form, which then precipitates to form sludge. This process increases the inefficiency of the plating bath and requires constant filtering. Prior art patents, such as US Pat. Nos. 4,717,460, 5,538,617 and 5,562,814, disclose components that can reduce the amount of tin oxidized.

Another advantage of using salts of alkyl or alkanol sulfonic acids is that they are much cheaper than the corresponding other acids. Recently, the only alkyl / alkanolic sulfonic acid commercially suitable for electroplating is methane sulfonic acid and the only alkali / alkaline earth metal / ammonium alkyl / alkanol sulfonic acid salt commercially suitable for electroplating is sodium isethionate. When comparing the prices of these two commercial products, sodium isethionate is less than half the price of methane sulfonic acid, even on a mole or weight basis.

Another embodiment of the present invention relates to the use of alkali metal, alkaline earth metal salts, and ammonium or substituted ammonium salts of alkyl and alkanol sulfonic acids, which have been found to improve the performance of fluoroborate electroplating baths. When used in such electroplating baths, these salt additives 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 the plating rate when these additives are not used. Has a plating rate. In addition, the use of these salts improves the quality of the deposit.

Thus, this embodiment of the present invention comprises adding a salt of alkyl and / or alkanol sulfonic acid to an fluoroborate ionic electroplating bath that can effectively enhance performance. The present invention relates to a method for improving the plating performance of a plating bath.

The salts used to improve the plating performance properties of the plating bath are in particular selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts. Particularly preferred salts are 2-hydroxy 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.

Another embodiment of the present invention relates to the use of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts of alkyl and alkanol sulfonic acids, which have been found to improve the performance of halide electroplating baths. When they are used in electroplating baths, it has been found that these salt additives generally increase the electroplating range so 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. In addition, the use of these salts improves the quality of the deposits.

Accordingly, this embodiment of the present invention includes an aqueous halide ion based electrolysis comprising the step of adding an amount of alkyl and / or alkanol sulfonic acid salt to the aqueous halide ion based electroplating bath to effectively enhance performance. The present invention relates to a method for improving the plating performance of a plating 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 especially selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts. Particularly preferred salts are 2-hydroxy 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 metal salts, alkaline earth metal salts, and ammonium or 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 for tin. It has a number of unexpected advantages such as improved oxidative stability. These plating baths can be plated at a much faster rate than plating baths without these additives. In addition, the quality 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 conventional ions and molecules found in the environment. In addition, these salts have a number of other advantages, including high solubility, low corrosiveness to equipment, good stability at high temperatures, and compatibility with many other metal salts.

Also, in general, these plating baths include corresponding metal salts or metal salts when alloy plating is required, and will include various additives for controlling the quality 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 plating baths is in stannous or reduced form. If oxidation occurs, tin is converted to stannic or oxidized form, which then precipitates to form sludge. This process increases the inefficiencies of the plating baths and requires constant filtering. Prior art patents, such as US Pat. Nos. 4,717,460, 5,538,617, and 5,562,814, disclose additives and / or processes that can reduce the amount of tin oxidized.

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 hydrodynamically controlled hull cells for 1 minute plating time at up to 30 amps. The plating strips were made of steel and pretreated by soaking in an alkali bath for 15 seconds and then rinsing, then immersing in 10% sulfate for 15 seconds and then rinsing 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-phenanthroline

number Additives and levels Plating test result One No additives At 5 amps, create a dark burn on the edge of high current density. At 10 amps, the burn is 12 mm wide at the edge of high current density 2 10 g / l sodium isethionate (calculated as isethionic acid) Glossy attachment in very light gray, at 10 amps-no burn 3 20 g / l sodium isethionate (calculated as isethionic acid) At 30 amps, a very light gray glittery attachment-no burns 4 1 g / l sodium sulfate At 10 amps, the bun has a width of 12 mm at the edge of high current density 5 30 g / l sodium sulfate At 10 amps, the bun has a width of 4 mm at the edge of high current density

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 of 600 amps / ft ² (ie when 15 amps is applied, the panel's current density is 600 amps / ft ² ), and the 30 amp range is equivalent to 1200 amps / ft ^2. to be. These results also show that sodium alkanol sulfate has a more significant effect, although sodium ions can have a positive effect on increasing the current density range.

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 At 5 amps, dark burn occurs at the edges of high current density 2 10 g / l sodium methane sulfonate (calculated as methane sulfonic acid) At 10 amps, a slightly reflective shiny attachment in very light gray-no burns 3 20 g / l sodium methane sulfonate (calculated as methane sulfonic acid) At 10 amps, a light gray shiny reflective attachment is formed at the edges of high current density-no burns

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 hydroxyl alkyl sulfonate in stannous sulfate / sulphate aqueous solution. The effect of iron on the stabilization of stannous ions on oxidation can be seen by comparing No. 3 to others. Oxygen was bubbled through 150 ml of the following solution for 64 hours at 120 ° F.

number SnSO₄                                              Sn²⁺                                              g / ℓ FeSO₄                                              Fe²⁺                                              g / ℓ H ₂ SO ₄ g / ℓ NaO ₃ SCH ₂ CH ₂ OH 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 5 23 10 80 0 3.2 6 23 10 80 30 0.2

Sulfonic acid plating bath

Salts of alkali / alkaline earth metal / ammonium alkyl / alkanol sulfonic acids during electroplating have rarely been used before, in which case the salts were first converted to acids. The present invention relates to the direct 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 can reduce the amount of methane sulfonic acid required in the plating bath. The reduction of MSA due to the addition of sodium isethionate optimizes plating performance by reducing the cost and improving the overall gloss of the tin or tin / lead deposits. Plating tests were carried out with the acid reduced to one-third of normal levels and no adverse effects were observed. Some plating tests have shown that addition of sodium isethionate significantly improves the overall deposit. The reduction in burns and bands improved the upper current density range. Commercially useful plating systems (trade name Technic MSA 90/10 manufactured by Technic Inc.) have increased the current density range from 120 ampere per square feet (240 ASF) to over 240 ASF.

Although the overall benefits of the addition of sodium isethionate depend on the plating system, it has been found that the reduction of the total free acid by up to 2/3 (66%) by the addition of sodium isethionate is acceptable in the following examples. .

Typical commercial MSA plating systems include approximately 15% v / v MSA (volume / volume methane sulfonic acid). 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 5% v / v MSA.

Plating performance tests were performed using HCHC (hydrodynamically controlled Halcel). Since the agitation is increased compared to the typical Halssel setting, the overall advantage in the upper current density (CD) can be confirmed by the addition of sodium isethionate. The results, when possible, were shown in mm and the width of the band. Both burns and bands in the high current density (HCD) to middle current density (MCD) regions affect the overall operable current density range of the plating bath. The current density ranges disclosed in the final column of the result table represent the current density ranges for optimal attachment. The addition of sodium isethionate to the plating bath reduces or eliminates burns 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 achievable at 5% v / v MSA was 10 amps. Application of up to 20 amps is possible by adding 15 g / l sodium isethionate to a system containing only 5% v / v MSA. The result table is as follows.

Plating bath solution:

15% v / v MSA

55 g / l Sn (Lead Tin Methane Sulfonate)
12 g / l Pb (lead methane sulfonate)

2 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 current 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

electric current additive Times / 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

electric current additive Times / 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:

5% v / v MSA

55 g / l Sn (Lead Tin Methane Sulfonate)
12 g / l Pb (lead methane sulfonate)

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

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

1% v / v TECHNI NF 800 HS 2nd "A" (Technic Incorporated)

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

Example 6 shows the result 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 Halssel specifications, the current density ranges of both 10 amp panels look similar. However, early panels without sodium isethionate have treeing along the panel edges. Tring is not seen in panels with sodium isethionate added. In practical applications, the presence of the triring narrows the operating range of the plating bath.

Example 6

electric current additive Times / mm Band in mm / mm Current density range 10 amps, 1 minute none 3 mm with trim 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

electric current additive Times / mm Band in mm / mm Current density range 10 amps, 1 minute 15 g / l sodium isethionate 2 mm, without tring none +400-60 ASF 15 amps, 1 minute 15 g / l sodium isethionate 2 mm, without tring none +600-LCD 20 amps, 1 minute 15 g / l sodium isethionate 10 mm, without tring 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 up the operating area of the system.

Plating bath composition:

10% v / v MSA

20 g / l Sn (Lead Tin Methane Sulfonate)

0.1 g / l salicylic acid

3 g / L Zepos WU 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 Times / 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 20 mm 400-200 ASF 20 g / l sodium methane sulfonate 5 mm none 400-60 ASF

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

Example 9

additive Times / 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 20 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 burn compared to sodium methane sulfonate. In fact, it will have a wider operating area. In addition, sodium isethionate brightens all deposits uniformly over the entire current density range.

Example 10

This example describes the performance of alkanol sulfonates to prevent oxidation of the stannous ions in a methane sulfonate-based tin plating bath solution.

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 (O₃SCH₃)₂                                              Sn²⁺                                              g / ℓ FeSO₄                                              Fe²⁺                                              g / ℓ NaO ₃ S (CH ₂ ) ₂ OH g / L HO ₃ SCH ₃ g / ℓ Reduction of Sn ²⁺ concentration g / ℓ One 23 10 0 0 5.7 2 23 10 30 0 4.2 3 23 10 0 15 4.5 4 23 10 30 15 3.6

The use of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts of alkyl 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. Metals and metal alloys include, but are not limited to, tin, lead, copper, cadmium, indium, iron, tin / lead, and tin / lead copper.

Fluoride Borate Plating Bath

Example 11

A standard Hassel test with a 267 mm hassel was performed at 2 amps for 5 minutes using a cathode rod agitation. The copper panels were plated after pickling and rinsing.

Plating bath composition:

35% v / v HBF ₄ (50% solution)

15 g / l tin (tin fluoride)

12 g / l lead (lead fluoride)

2 g / l hydroquinone

26 g / l boric acid

2% v / v HBF ₄ Makeup

number additive result One none Matte gray attachment with burns 5 mm wide at high current density edges 2 20 g / l sodium methane sulfonate Attachment is bright and bun narrows to 4mm wide 3 20 g / l sodium isethionate Attachment is bright and bun narrows to 3.5mm wide

This example shows that when adding sodium methane sulfonate or sodium isethionate, this plating bath can be used at high current densities and the appearance of the coating expands.

Halide plating bath

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

Example 12
The halide based plating bath was carried out on HCHC, ie hydrodynamically controlled Halcel. The plating strips were made of steel and pretreated by soaking and rinsing in alkali for 15 seconds, then 15 seconds in 10% sulfonic acid and rinsing again.

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

Plating bath composition (room temperature):

19.6 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)

delete

number Current / time additive result One 2 amps / 2 minutes none Dendritic crystal growth 2 mm wide at the edge of high current density, the remainder glossy / matte white 2 3 amps / 2 minutes none Thick burns 6 mm wide at the edges of high current density. Same color as number 1 3 3 amps / 2 minutes 4 g / l sodium isethionate The bun is not clearly formed and narrows to about 3 mm. Uniform, smooth, neat non-gloss finish 4 3 amps / 2 minutes 6 g / l sodium isethionate Decreases only at edges of high current density. Uniform, smooth and neat non-gloss finish equivalent to number 3

This example shows that by adding a very small amount of sodium isethionate to the halide plating bath, the operable current density range can be increased by 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 inherent mixtures from which metal coatings with the required properties can be made. It is well known that the overall ionic conductivity of a solution depends on the nature and concentration of each of the ions. Special interactions between different ionic species and / or solvent molecules determine the overall conductivity and may affect the electroadhesion process. However, ionic conductivity is the only variable to consider in formulating a plating bath.

It is also well known that the structure of the electrical double layer can affect the rate of electrical deposition. "Journal of Electroanalytical Chemistry," published by Lassia et al., 1989, pp. 266 68-81; "Journal of Electroanalytical Chemistry," published by 1990, 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., Pages 427 to 146, certain metal ions (Cu ⁺ , Cd ²⁺ , or Zn ^2). It has been experimentally demonstrated that the electroreduction rate constant (such as ⁺ ) depends on the solvation capacity of the solvent and the size of the cation of the electrolyte. This effect was due to 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 γ _M ) + α _a nFΦ ^d / RT-α _a nF (EE _s Where k _f is the apparent rate constant, k _O is the potential-independent portion of the rate constant, γ _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.

Supporting electrolyte The size of the counter ions affects the potential (Φ ^d ) and ultimately affects the rate constants of the overall electroreduction process (as described above, such as Lasia, Faucet, etc., and Lasia, etc.). See author).

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 auxiliary electrolyte.

In the present invention, the cations and / or anions are not added only to maintain the ionic conductivity of the electrolyte and / or the fusion of the adherent ions, but instead they are electroadhesive by affecting the bilayer structure, thus the mechanism of the electroreduction revolution. Directly affect the process.

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

Claims (74)

A process for producing an aqueous electroplating bath selected from the group consisting of sulfates, sulfonic acids, fluoroborate salts, and halide electroplating baths, with an increased current density range for plating, Adding 4 to 30 g / l of a salt of alkyl and alkanol sulfonic acid to the electroplating bath, The salt to be added is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts, Method for producing an aqueous electroplating bath. delete The method of claim 1, wherein the salt is a salt of 2-hydroxy ethyl sulfonic acid, Method for producing an aqueous electroplating bath. The method of claim 3, wherein the salt is sodium isethionate, Method for producing an aqueous electroplating bath. The method of claim 1, wherein the electroplating bath is a sulfate electroplating bath, Method for producing an aqueous electroplating bath. The method of claim 1, wherein the electroplating bath is a sulfonic acid electroplating bath, Method for producing an aqueous electroplating bath. The method of claim 1, wherein the electroplating bath is a fluoroborate electroplating bath, Method for producing an aqueous electroplating bath. The method of claim 1, wherein the electroplating bath is a halide electroplating bath, Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a tin or tin alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a nickel or nickel alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a copper or copper alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a chromium or chromium alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is an iron or iron alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a rhodium or rhodium alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a ruthenium or ruthenium alloy plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is an iron / zinc plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the electroplating bath is a tin / zinc plating bath. Method for producing an aqueous electroplating bath. The method according to any one of claims 1, 3, 4, 5, 6, 7, 8, wherein the method of producing the aqueous electroplating bath comprises at least increasing the upper current density range of the electroplating bath at least twice. Method for producing an aqueous electroplating bath. As an aqueous sulfate electroplating bath, An electrolyte having a sulfate anion source; One or more platingable soluble metal salts; And And salts of 4 to 30 g / l alkyl sulfonic acid and alkanol sulfonic acid that can increase the plating current density range of the aqueous sulfate electroplating bath, The plateable metal is selected from the group consisting of tin, nickel, copper, chromium, cadmium, iron, rhodium, ruthenium, zinc, and mixtures thereof, wherein the sulfonate salt is an alkali metal salt, an alkaline earth metal salt, and an ammonium salt or a substituted ammonium salt Selected from the group consisting of: Aqueous sulfate electroplating bath. delete The method of claim 20, wherein the sulfonate salt is a salt of 2-hydroxy ethyl sulfonic acid, Aqueous sulfate electroplating bath. The method of claim 22, wherein the salt is sodium isethionate Aqueous sulfate electroplating bath. As a method for producing a sulfonic acid electroplating bath, Replacing at least a portion of the alkyl sulfonic acid electrolyte with salts of 4 to 30 g / l alkyl sulfonic acid and alkanol sulfonic acid, which can increase the plating density range of the sulfonic acid based electroplating bath, The sulfonate is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts, The method for producing a sulfonic acid-based electroplating bath. delete The method of claim 24, wherein the sulfonic acid is alkyl sulfonic acid, Method for producing a sulfonic acid electroplating bath. 27. The method of claim 26, wherein said alkyl sulfonic acid is methane sulfonic acid, Method for producing a sulfonic acid electroplating bath. The method of claim 24, wherein the salt is 2-hydroxy ethyl sulfonate, Method for producing a sulfonic acid electroplating bath. 25. The method of claim 24, wherein the electroplating bath is a tin electroplating bath. Method for producing a sulfonic acid electroplating bath. The method of claim 24, wherein the electroplating bath is a lead electroplating bath, Method for producing a sulfonic acid electroplating bath. 25. The method of claim 24, wherein the electroplating bath is a tin / lead electroplating bath. Method for producing a sulfonic acid electroplating bath. Plating method of increasing the upper current density range of the tin methane sulfonate plating bath by more than two times so that tin plating can be performed at high speed. Adding 4 to 30 g / l of sodium or potassium methane sulfonate to the plating bath, Plating method to increase the upper current density range. Plating method of increasing the upper current density range of the tin / lead methane sulfonate plating bath more than two times to perform plating at high speed, Replacing at least a portion of the methane sulfonic acid with sodium isethionate, Plating method to increase the upper current density range. The method of claim 33, wherein up to 50% of the methane sulfonic acid is replaced with sodium isethionate. Plating method to increase the upper current density range. The method of claim 33, wherein up to 75% of the methane sulfonic acid is replaced with sodium isethionate. Plating method to increase the upper current density range. The method of claim 33 wherein up to 90% of the methane sulfonic acid is replaced with sodium isethionate. Plating method to increase the upper current density range. A method of preventing oxidation of stannous ions in a tin plating bath containing methane sulfonic acid, Adding 4 to 30 g / l of a salt of alkyl and alkanol sulfonic acid, A method of preventing oxidation of stannous ions. 38. The salt of claim 37, wherein the salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts. A method of preventing oxidation of stannous ions. As an aqueous sulfonic acid electroplating bath, Alkyl or alkanol sulfonic acids; One or more platingable soluble metal salts; And Salts of 4 to 30 g / l alkyl sulfonic acid and alkanol sulfonic acid capable of increasing the plating density range of the aqueous sulfonic acid electroplating bath; Including, The plateable metal is selected from the group consisting of tin, lead, copper, cadmium, indium, iron, and mixtures thereof, and the sulfonate is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts felled, Aqueous sulfonic acid electroplating bath. delete The method of claim 39, wherein the sulfonate is a salt of 2-hydroxy ethyl sulfonic acid, Aqueous sulfonic acid electroplating bath. 42. The method of claim 41, wherein the sulfonate is sodium isethionate, Aqueous sulfonic acid electroplating bath. As a method for producing an aqueous fluoroborate-based electroplating bath, Adding 4 to 30 g / l of an alkyl sulfonic acid and a salt of alkanol sulfonic acid to the plating bath, The sulfonate is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts, Method for producing an aqueous fluoroborate electroplating bath. delete The method of claim 43, wherein the salt is a salt of 2-hydroxy ethyl sulfonic acid. Method for producing an aqueous fluoroborate electroplating bath. 46. The method of claim 45, wherein said salt is sodium isethionate, Method for producing an aqueous fluoroborate electroplating bath. The electroplating bath of claim 43, 45, 46, wherein the electroplating bath is a tin or tin alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The method of any of claims 43, 45, 46, wherein the electroplating bath is a lead or lead alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The electroplating bath of any of claims 43, 45, 46, wherein the electroplating bath is a copper or copper alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The method of any of claims 43, 45, 46, wherein the electroplating bath is an indium or indium alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The method of any of claims 43, 45, 46, wherein the electroplating bath is an iron or iron alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The method of any of claims 43, 45 and 46, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. Method for producing an aqueous fluoroborate electroplating bath. 47. The electroplating bath of any of claims 43, 45, 46, wherein the electroplating bath is a tin / lead plating bath. Method for producing an aqueous fluoroborate electroplating bath. The electroplating bath of claim 43, 45, 46, wherein the electroplating bath is a tin / lead / copper plating bath. Method for producing an aqueous fluoroborate electroplating bath. 44. The method of claim 43, wherein the method of manufacturing the electroplating bath comprises increasing at least twice the upper current density range of the plating bath. Method for producing an aqueous fluoroborate electroplating bath. As an aqueous fluoroborate electroplating bath, Fluoride borate anion sources; One or more platingable soluble metal salts; And Salts of 4 to 30 g / l alkyl sulfonic acid and alkanol sulfonic acid capable of increasing the plating density range of the aqueous fluoroborate electroplating bath; Including, The plateable metal is selected from the group consisting of tin, lead, copper, cadmium, indium, iron, and mixtures thereof, and the sulfonate is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts felled, Aqueous fluoroborate electroplating bath. delete The method of claim 56, wherein the sulfonate is a salt of 2-hydroxy ethyl sulfonic acid. Aqueous fluoroborate electroplating bath. The method of claim 58, wherein the sulfonate is sodium isethionate Aqueous fluoroborate electroplating bath. As a manufacturing method of an aqueous halide ion type electroplating bath, Adding 4 to 30 g / L of a salt of alkyl and alkanol sulfonic acid to the electroplating bath, Method for producing an aqueous halide ion electroplating bath. 61. The method of claim 60, wherein the halide ions are selected from chlorides and fluorides. Method for producing an aqueous halide ion electroplating bath. 61. The method of claim 60, wherein said salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts. 63. The method of claim 62, wherein the salt is a salt of 2-hydroxy ethyl sulfonic acid. Method for producing an aqueous halide ion electroplating bath. 64. The method of claim 63, wherein the salt is sodium isethionate, Method for producing an aqueous halide ion electroplating bath. The electroplating bath of claim 60, wherein the electroplating bath is a tin or tin alloy plating bath. Method for producing an aqueous halide ion electroplating bath. 65. The electroplating bath of any of claims 60-64, wherein the electroplating bath is a nickel or nickel alloy plating bath. Method for producing an aqueous halide ion electroplating bath. The electroplating bath of claim 60, wherein the electroplating bath is copper or a copper alloy plating bath. Method for producing an aqueous halide ion electroplating bath. The electroplating bath of claim 60, wherein the electroplating bath is a zinc or zinc alloy plating bath. Method for producing an aqueous halide ion electroplating bath. The electroplating bath of claim 60, wherein the electroplating bath is a cadmium or cadmium alloy plating bath. Method for producing an aqueous halide ion electroplating bath. 61. The method of claim 60, wherein the method of manufacturing the electroplating bath comprises increasing at least twice the upper current density range of the plating bath. Method for producing an aqueous halide ion electroplating bath. As an aqueous metal alloy halide electroplating bath, An electrolyte having a halide ion source; One or more platingable soluble metal salts; And A salt of an alkyl sulfonic acid and an alkanol sulfonic acid of 4 to 30 g / l, which can increase the plating density range of the aqueous metal alloy halide electroplating bath, The plateable metal is selected from the group consisting of tin, nickel, copper, zinc, cadmium, and mixtures thereof, and the sulfonate is selected from the group consisting of alkali metal salts, alkaline earth metal salts, and ammonium salts or substituted ammonium salts, Aqueous metal alloy halide electroplating bath. delete 72. The method of claim 71, wherein the sulfonate is a salt of 2-hydroxy ethyl sulfonic acid, Aqueous metal alloy halide electroplating bath. 75. The salt of claim 73 wherein the salt is sodium isethionate Aqueous metal alloy halide electroplating bath.