JP2982658B2 - Method of lowering metal concentration in electroplating solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is to prevent waste of precious resources, especially by depositing excess metal ions exceeding the upper limit of the electroplating solution of nickel, cobalt, iron or their alloys. The metal concentration in the electroplating solution can be easily reduced without lowering the metal concentration in the electroplating solution to the control upper limit value or less without polluting the environment. Regarding the lowering method.

[0002]

2. Description of the Related Art Electroplating is performed using a soluble anode, for example, with an electroplating solution of nickel, cobalt, iron or an alloy thereof (hereinafter, these are collectively referred to as nickel-based). You have
The nickel-based metal concentration in the plating solution tends to increase. This is because the anode dissolution efficiency in the above plating solution is close to 100%, while the cathode current efficiency is usually about 95%.
This is because the nickel-based metal concentration in the plating solution gradually increases due to the efficiency difference.

[0003] When the metal concentration in the plating solution increases, the throwing power of the plating solution decreases. Therefore, if the increased amount of metal ions is removed from the plating solution, the uniform electrodeposition of the plating solution can be maintained. Maintaining this throwing power is particularly important in nickel-based electroplating solutions.

Conventionally, as a method of removing excess metal ions, a part or all of a plating bath is discarded to remove metal ions and reduce the metal concentration in a plating solution. However, this method wastes valuable resources and is not desirable from the viewpoint of environmental pollution.

[0005] Unnecessary metals have also been removed by a neutralization precipitation method. However, this method wastes valuable resources, and it is very difficult to filter metal hydroxide generated by the neutralization reaction, and the plating solution component is contained in the metal hydroxide. There is a problem that is.

Further, there is a method of removing unnecessary metals in a plating solution by using an ion exchange resin or a chelating resin. However, it is conceivable that these resins may be dissolved in the plating solution and adversely affect plating. there is a possibility. In addition, since the plating solution contained in the resin is extruded and recovered with water, there is a problem that the amount of the plating solution increases. In addition, there is a problem that the metal adsorbed on these resins must be desorbed with an acid.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent waste of precious resources, and to easily reduce the metal concentration in an electroplating solution to a level lower than a control upper limit value without polluting the environment. Accordingly, it is an object of the present invention to provide a method for lowering the metal concentration in an electroplating solution, which makes it possible to maintain the uniform electrodeposition of the plating solution.

[0008]

The present inventors have conducted intensive studies to achieve the above object, and as a result, when electrolysis was performed using an insoluble anode as the anode, metal ions in the catholyte were deposited on the cathode. Paying attention to the reduction of metal concentration in the solution, the electroplating solution and the anolyte are separated by a cation exchange membrane and the above electrolysis is performed to remove metal ions in the plating solution from the plating solution. Not only can the metal be easily recovered, but also if the plating solution contains a halide, the electrolysis is carried out in a halide-free anolyte using an insoluble anode. The inventors have found that generation of gas can be prevented, and have accomplished the present invention.

That is, the present invention relates to a nickel-based electroplating which contains one or more metal ions and halogen ions of nickel ions, cobalt ions and iron ions, and gives 10 to 99% throwing power. Liquid,
In the metal concentration lowering method for removing the surplus metal ions from the electroplating solution in which the metal ions have exceeded the upper limit concentration value, the inside of the electrolytic cell is separated into an anode chamber and a cathode chamber by a cation exchange membrane, and the anode chamber is separated. An anolyte which is a sodium salt, a potassium salt, an aluminum salt or a magnesium salt and does not contain a halogen ion is placed therein, and an electroplating solution in which the above metal ion exceeds the upper limit concentration is placed in a cathode chamber. The cathode is immersed in the anolyte, and the insoluble anode is immersed in the anolyte to form 0.1 to 3 A / dm ^2.
Electrolysis at the cathode current density of the above, the metal ions in the electroplating solution are deposited as metal on the cathode, and the electroplating solution from which excess metal ions have been removed and the halogen ion concentration has been maintained is subjected to the above-mentioned uniform electrolysis. Provided is a method for reducing a metal concentration in an electroplating solution, wherein the method is used as an electroplating solution that provides adhesion.

Hereinafter, the present invention will be described in more detail.
In the method for reducing the metal concentration in the electroplating solution of the present invention, the electroplating solution to be treated is a catholyte. here,
As the metal ions contained in the plating solution, nickel-based metal ions are suitable, and these may be nickel, cobalt, or iron ions alone, or may include two or more of these. The electroplating solution preferably has a total concentration of each metal ion contained in the electroplating solution of 1 to 45 g / l, more preferably 4 to 15 g / l. When the concentration is less than 1 g / l, the throwing power is very good, but the plating limit current density is small and the plating productivity is lacking, and when it exceeds 45 g / l, the throwing power may be reduced.

In order to further improve the throwing power of the plating solution, a conductive salt is added to the nickel-based electroplating solution while the metal ion concentration is lowered as described above. As the conductive salt to be added to the plating solution of the present invention, a water-soluble salt of a metal selected from alkali metals, alkaline earth metals and aluminum is preferable, for example,
Sodium chloride, potassium chloride, magnesium chloride, aluminum chloride, sodium sulfate, potassium sulfate, magnesium sulfate, aluminum sulfate, sodium bromide, potassium bromide, magnesium bromide, aluminum bromide, etc. can be used. Or two or more of them may be used in combination.

The amount of the conductive salt to be added is 50 to 50.
It is preferably 0 g / l, particularly preferably 100 to 400 g / l. If the addition amount is less than 50 g / l, there is no effect of sufficiently improving the throwing power, while the higher the concentration of the conductive salt, the more the throwing power is improved. In some cases, it does not dissolve.

It is also preferable to add a buffer, but as the buffer, an organic acid salt such as boric acid or citrate can be suitably used. The concentration of the buffer is 10 to
It is preferably 100 g / l, particularly preferably 20 to 80 g / l.

As the plating solution of the present invention, a plating solution containing a halide in the solution is effective.

Examples of the halide include nickel chloride, cobalt chloride, iron chloride, nickel bromide, cobalt bromide, iron bromide, sodium chloride, potassium chloride, magnesium chloride, aluminum chloride, sodium bromide, potassium bromide, and bromide. Magnesium oxide and the like. These halides are added as the metal ion source or the conductive salt.

The content of the halide is 3 to 40.
0 g / l, especially 5 to 100 g / l, is preferred.

The plating solution is used after being adjusted to be acidic, but the pH is preferably 2 to 6, particularly preferably 3 to 5.

Here, a plating solution suitable as an object of the present invention contains the above-mentioned components, and was subjected to a test using a Harling cell (polar ratio: 5: 1) as a plating tester, and the weight of the plating film deposited on the cathode was measured. Is weighed, and the throwing power (T (%)) calculated according to the following Field throwing power formula is 10 to 99%, more preferably 20 to 80%.

T (%) = 100 (PM) / (P + M−2) (where P is the distance ratio between the anode and the cathode (here, 5), and M is the metal deposited on the cathode) It is the weight ratio of the plating film.)

The uniform electrodeposition test using this Harling cell is described in Japanese Patent Publication No. 22158/1990, and the uniform electrodeposition test of the present invention is performed according to the description in this publication.

In the present invention, when the concentration of metal ions in the electroplating solution exceeds the upper limit of the control value and the throwing power is lowered or is likely to be lowered, the excess of the concentration exceeding the upper limit value is required. The metal ions are immersed in the catholyte using the electroplating solution, and the anolyte separated by using the cation exchange membrane as a diaphragm. Is deposited and removed.

Here, as the anolyte used, if the anolyte contains a halide, a halogen gas is often generated at the time of electrolysis. Therefore, an anolyte containing no halide is preferable. As such an anolyte, a solution of sulfuric acid, sulfate, nitric acid, nitrate, phosphoric acid, phosphate, hydroxide, organic acid salt, organic acid, or the like can be used. The anolyte of the present invention may be used alone or in combination of two or more.

The above salts are preferably sodium salts, potassium salts, aluminum salts and magnesium salts, particularly potassium sulfate, sodium sulfate, magnesium sulfate, sodium citrate, potassium citrate, sodium hydroxide, potassium hydroxide. Is more preferable.

The concentration of these salts and the like is not particularly limited, and may be a concentration at which conductivity during electrolysis can be obtained, but is preferably 10 to 300 g / l. 1
If it is less than 0 g / l, an electrolytic voltage is applied, which is uneconomical. On the other hand, the conductivity is improved almost in proportion to the concentration of salts and the like, but when the concentration of salts and the like exceeds 300 g / l, the effect is not changed even if added more.

A cation exchange membrane is used as the electrolytic diaphragm for separating the electroplating solution from the anolyte. As the cation exchange membrane, a commercially available one can be used, but one having a Teflon-based substrate is particularly preferable because of its excellent oxidation resistance. For example, Nafion (trade name, manufactured by DuPont) can be suitably used.

As the anode for electrolysis, an insoluble anode which does not dissolve chemically and electrochemically in the above-mentioned anolyte, for example, nickel, cobalt, stainless steel, carbon, platinum-plated titanium, DSA or the like is preferably used. can do.

On the other hand, as a cathode for electrolysis, nickel,
Cobalt, stainless steel, titanium plate and aluminum plate can be suitably used. The deposited metal can be used as it is or separated from the substrate and collected.

Further, the current density is appropriately selected, and the cathode current density is 0.1 to 3 A / dm ² , especially 0.5 to ^{2 A} / dm ² .
dm ² is preferable. The temperature of the plating solution during the electrolysis is preferably from 20 to 70C, particularly preferably from 30 to 60C. In addition, air stirring, cathode locking, liquid feeding stirring with a pump, stirring with a stirrer, and the like can be employed as stirring.

In the method for reducing the metal concentration in the electroplating solution of the present invention, since an insoluble anode is used, no metal ions are supplied from the anode to the plating solution, and the metal ions in the plating solution are deposited by electrodeposition. Only decreases. In addition, since the cation exchange membrane is used, the halogen ions do not move into the anolyte, so that even if the anolyte contains no halide, the halogen ions may be mixed into the anolyte. No halogen gas is generated from the anolyte. In addition, it is possible to prevent a situation in which extra anions such as sulfate ions increase from the anolyte to the plating solution.

The above-mentioned electrolysis can be carried out by providing an electrolytic tank separately from the plating tank or the plating solution storage tank and circulating the electroplating solution between the plating tank or the plating solution storage tank and the electrolytic tank. Of course, it is not limited to this.

FIG. 1 shows an example of the electrolytic cell. In this example, the inside of the electrolytic cell 1 is partitioned by two cation exchange membranes 2 and 2, an anolyte 4 is put into the anode chamber 3 between the two cation exchange membranes 2 and 2, and an anode 5 is further provided. In addition, both cation exchange membranes 2 and 2 and both side walls 1a and 1 of electrolytic cell 1 are formed.
The cathode spaces (6, 6) are respectively set as cathode chambers (6, 6), and catholyte (electroplating solution) 7, 7 is put in these chambers, and cathodes 8, 8 are further arranged. May be provided with one anode chamber 3 and one cathode chamber 6, respectively.

[0032]

As described above, according to the method for lowering the metal concentration in the electroplating solution of the present invention, the metal in the electroplating solution is electrodeposited on the cathode to convert the soluble anode into the electroplating solution. The metal concentration in the plating solution increased by the immersion electroplating can be reduced below a certain limit. Then, the metal in the electroplating solution can be easily recovered, and waste of precious resources can be prevented, and uniform electrodeposition of the electroplating solution can be maintained without polluting the environment.

[0033]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 Using the electrolytic cell shown in FIG.
Electrolysis was performed under the following conditions while circulating the following electroplating solution with the plating solution storage tank.

Electroplating solution sodium sulfate 300 g / l nickel sulfate 19 g / l nickel chloride 40 g / l (nickel ion concentration 14 g / l) boric acid 40 g / l throwing power (T (%) by the above test) 35% pH 4 .6 liquid volume 700 liters

Electrolysis conditions Anolyte: sodium sulfate solution 100 g / l: solution volume 50 liters Anode 0.5 m ² platinum-plated titanium lath plate Cathode 0.8 m ² SUS304 plate 1 sheet each 2 sheets in total Cation exchange membrane Nafion 417 (manufactured by DuPont, trade name) 2 sheets of 1 m ² are used Plating solution temperature 55 ° C. Liquid stirring Air stirring Cathode current density 1.25 A / dm ² Electrolysis time 10 hours

That is, the electrolytic treatment was performed at a total current of 200 A for 10 hours. Therefore, the amount of electrolysis is 2000 AH. By the above electrolytic treatment, 2000 g of nickel was electroformed.

Next, the nickel concentration and the pH in the electroplating solution after the above treatment were measured. The pH of the plating solution is 4.
From 6 to 4.4. The nickel concentration went from 14 g / l to 11.1 g / l.

The plating solution treated as described above had a throwing power of 39%. Plating was performed using this plating solution and the plating properties were evaluated. No abnormalities were found in the plating properties. . From the above, it was found that the intended purpose was achieved by this diaphragm electrolysis operation.

Example 2 In Example 1, the electroplating solution was an electroplating solution having a cobalt concentration of 1 g / l and a [nickel + cobalt] concentration of 14 g / l.
%), And electrolysis was carried out in the same manner as in Example 1 except that the anode was changed to mode J (made by Ishifuku Metals, trade name) which was an insoluble anode. By this electrolytic treatment, 2000 g of [nickel + cobalt] was deposited.

After this electrolysis, the [nickel + cobalt] concentration and the pH in the plating solution were measured. The pH of the plating solution is 4.
From 6 to 4.4. The [nickel + cobalt] concentration went from 14 g / l to 11.1 g / l.

The throwing power of the plating solution subjected to the above treatment was 39%. Plating was performed using this plating solution and the plating properties were evaluated. No abnormality was found in the plating properties. . From the above, it was found that the intended purpose was achieved by this diaphragm electrolysis operation.

Example 3 In Example 1, the electroplating solution was prepared by changing the concentration of divalent iron ions to 5 g / l and [Ni +
Iron] with a plating solution having a concentration of 14 g / l (uniform electrodeposition 3
Electrolysis was performed in the same manner as in Example 1 except for 4%). By this electrolytic treatment, 1950 g of [nickel + iron] was deposited.

After this electrolysis, [nickel +
Iron] concentration and pH were measured. The pH of the plating solution changed from 4.6 to 4.4. [Ni + iron] concentration is 14g /
from 1 to 11.2 g / l.

The plating solution treated as described above had a uniform electrodeposition property of 38%. Plating was performed using this plating solution, and the plating properties were evaluated. No abnormalities were found in the plating properties. . From the above, it was found that the intended purpose was achieved by this diaphragm electrolysis operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an electrolysis apparatus used for carrying out the method of the present invention.

FIG. 2 is a schematic view showing another example of the electrolysis apparatus.

[Explanation of symbols]

 2 Cation exchange membrane 4 Anolyte 5 Anode 7 Catholyte 8 Cathode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C25D 21/18

Claims (2)

(57) [Claims] 1. A nickel-based electroplating solution containing one or more metal ions of nickel ions, cobalt ions and iron ions and a halogen ion, and giving 10 to 99% throwing power. In the metal concentration lowering method for removing the excessive metal ions from the electroplating solution in which the metal ions have exceeded the upper limit concentration value, the inside of the electrolytic cell is separated into an anode chamber and a cathode chamber by a cation exchange membrane, and A anolyte containing a sodium salt, potassium salt, aluminum salt or magnesium salt and not containing a halogen ion is put in a chamber, and an electroplating solution in which the above metal ion exceeds the upper limit concentration is put in a cathode chamber. while immersed cathode in the liquid, subjected to electrolysis at cathode current density of 0.1~3A / dm ² by immersing the insoluble anode in the anolyte, the The metal ion in the vapor plating solution is deposited as a metal on the cathode, and the excess metal ion is removed, and the electroplating solution having a maintained halogen ion concentration is used as the electroplating solution that provides the uniform electrodeposition property. A method for lowering the metal concentration in an electroplating solution, characterized in that: 2. The method according to claim 1, wherein the electroplating solution contains one or more of nickel ions, cobalt ions and iron ions, and the total amount of the electroplating solution is 1 to 45 g / l. .