JP2689076B2 - Method for maintaining and recovering etching solution capacity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for maintaining and recovering the capacity of an etching solution used in a wet etching process of a metal material, which is an important process in manufacturing a circuit board used for a part of electronic parts or assembling.

That is, not only can the aged etching solution be regenerated, the etching solution can be prevented from deteriorating by connecting to the etching equipment in use, and the etching effect can be maintained in the optimum state. It enables production at an etching speed to improve productivity, can significantly extend the service life of the etching solution, and can significantly reduce the amount of used waste solution, which is economically effective. The present invention relates to a method for recovering and maintaining the etching ability which is not only large but also contributes to resource saving.

[0003]

2. Description of the Related Art Ferric chloride or cupric chloride aqueous solution is often used as an etching solution for wet etching used for manufacturing printed circuit boards and fine processing of electronic parts. If a certain amount of such etching liquid dissolves a material to be etched such as copper or stainless steel, its dissolving ability decreases and the material ages. The cause of aging is 3 in iron-based etching solutions.
Divalent iron ions (Fe ³⁺ ) become divalent iron ions (Fe ²⁺ ), and divalent copper ions (C
This is because u ²⁺ ) is reduced to monovalent copper ions (Cu ⁺ ).

Therefore, there has been proposed a method of oxidizing such an aged etching solution to return Fe ²⁺ to Fe ³⁺ or Cu ⁺ to Cu ²⁺ . For that purpose, a chemical method using an oxidizing agent or an electrochemical method by electrolysis as disclosed in JP-A-2-310382 has been proposed.

[0005]

However, the regeneration method by the chemical method uses sodium hypochlorite,
Since it is performed using ozone, when sodium hypochlorite is used, sodium chloride accumulates in the etching solution along with regeneration, and there is the inconvenience that sodium hypochlorite must be constantly replenished. However, when ozone is used, it is a gas-liquid reaction, so that there is a disadvantage such as poor efficiency.

Further, the regeneration method by the electrochemical method is
As disclosed in JP-A-2-310382,
The electrolytic chamber is divided into an anode chamber and a cathode chamber by an anion exchange membrane, and is a method of supplying an etching solution to the anode chamber for electrolytic oxidation, which is called a plate-and-frame flow cell. In general, a commercial product is used, so it is necessary to apply a large current, and if the concentration of ferrous chloride (FeCl ₂ ) or cuprous chloride (CuCl) is low, Cl ^- ion At the same time, it will be oxidized and chlorine gas will be generated, which will harm the working environment.

Further, in order to eliminate this inconvenience, Japanese Patent Publication Sho 63
No. 27427, a method of suspending a large amount of activated carbon powder particles in an etching solution to react with generated chlorine, and Japanese Patent Publication No. 5-33315 and Japanese Patent Application Laid-Open No. 2-308382. As described above, there has been proposed a method of performing an oxidation reaction while maintaining the potential of the anode at a potential at which chlorine is not generated. However, in the former case, the solid matter will be suspended in the etching solution, which will be a source of harm to the fine etching process.In the latter case, the anode potential will be kept below the chlorine generation potential to prevent chlorine generation. Therefore, it is natural that chlorine generation can be prevented in principle.
It is unavoidable that the reaction rate decreases and the regeneration rate extremely slows as the concentration of Cl ₂ or CuCl decreases.

The object of the present invention is not to reduce the reaction rate until the concentration of ferrous chloride (FeCl ₂ ) or cuprous chloride (CuCl) is sufficiently diluted, and while suppressing the generation of chlorine gas, Another object of the present invention is to provide a method for maintaining and recovering the ability of an etching solution that can be electrolytically oxidized.

In other words, the concentration of ferrous chloride (FeCl ₂ ) or cuprous chloride (CuCl) in the etching solution can be maintained at a low level for a long period of time to perform stable etching operation, and to connect to etching equipment. By doing so, it is intended to provide a method for recovering and maintaining the capacity of an etching solution, which enables efficient etching operation, improves productivity, and contributes to resource saving.

[0010]

According to the present invention, in a conventional electrolytic oxidation regeneration method, a commercially available electrolytic cell is used, and this commercially available electrolytic cell uses a liquid-impermeable electrode plate. Therefore, the present invention was made by paying attention to the occurrence of the inconvenience.

That is, since the electrolytic reaction is generally carried out on the surface of the electrode, the concentration of the reactant may be increased or the electrode area may be increased by using a large number of electrodes in order to increase the reaction rate. However, when a liquid-impermeable electrode is used, even if the number of electrodes is increased, most of the substances to be reacted pass through the gap between the anode, the cathode, and the diaphragm without participating in the reaction. I will end up. For this reason, the reaction rate is slow, and it becomes difficult to perform an electrolytic reaction particularly when the concentration of the substance to be reacted is low. Despite the basic drawbacks of such an electrolysis method in the case of a chloride solution, even if the electrolysis method has a basic drawback, if the voltage between the anode and the cathode is increased in order to increase the reaction rate, the anode potential will generate chlorine. It will go up to the area and chlorine will be generated at the same time. In particular, this chlorine generation tends to occur when the concentration of the substance to be reacted is low. In order to prevent this, even if the potential of the anode is controlled to be equal to or lower than the chlorine generation potential, the reaction speed is extremely slow, and it is only a passive measure.

In the present invention, as a means for proactively solving this problem, by improving the reaction rate on the electrode, the oxidation reaction of Fe ²⁺ and Cu ⁺ proceeds sufficiently fast even when the concentration thereof is low, As a result, a method is proposed in which a high current can be applied and the reaction can be carried out until the reaction is completed without generation of chlorine. The invention according to claim 1 provides an anode chamber having an anode and a cathode chamber having a cathode. , Using an electrolytic cell having an anion exchange membrane for partitioning the anode chamber and the cathode chamber, using a liquid-permeable electrode composed of a porous structure for suppressing the chlorine generation in the anode, in the anode chamber While supplying an etching solution and a cathode electrolyte solution in which chloride is dissolved to the cathode chamber, p of the electrolyte solution in the cathode chamber is supplied.
H was measured, and when the pH became 10, the hydrochloric acid was added to the electrolytic solution until the pH became 7 or less, and the operation was performed in the range of pH 0 to 10, and the pH of the electrolytic solution was 7 to 10 Within the range, the solid metal hydroxide produced by the metal ions transferred into the electrolytic solution is removed by filtration.

That is, the first feature of the present invention resides in the above-mentioned electrolytic cell. First, this electrolytic cell will be described. The electrolytic cell shown in FIG. 1 has an anode chamber 4 having an inlet 2 and an outlet 3 on both sides of an electrolyte permeable anode 1 made of a porous body, and a cathode 5.
And a cathode chamber 8 having an inlet 6 and an outlet 7, and the anode chamber 4 and the cathode chamber 8 are partitioned by an anion exchange membrane 9, and the cathode chamber 8 is chlorinated from its inlet 6. The cathode electrolyte solution in which the substance is dissolved is supplied, discharged from the outlet 7 and circulated between the cathode electrolyte solution storage tank and the anode chamber 4.
Is supplied with an aged etching solution containing Fe ²⁺ or Cu ⁺ from its inlet 2, is passed through the anode 1 and is discharged from an outlet 3, and is connected to a liquid part such as an etching solution storage tank or etching equipment. While circulating between them, the anode 1 and the cathode 5
A direct current is passed between and to replace Fe ²⁺ to Fe ³⁺ or Cu ⁺
Cu ²⁺ is continuously electrolytically oxidized to recover and maintain the etching ability.

The anode 1 in the electrolytic cell shown in FIG.
Is electrically conductive and has corrosion resistance such as carbon, titanium, zirconium, etc.
Tantalum and alloys thereof, preferably composed of a liquid-permeable plate-like porous body made of carbon,
In addition, as shown in FIG. 2, a porous structure constituted by filling the inside of the anode chamber 1 partitioned by the anion exchange membrane 9 with the conductive filling body 10 and inserting the power feeding body 11 in the central portion thereof. The anode 1 may be formed by using the above.

In this case, the filling body 10 is made of carbon or a conductive metal, and is mainly made of spherical particles or fibrous or chip-like shapes.

The porous structure of the present invention may be composed of only the porous body or may be composed of a combination of a large number of packing bodies, or may be composed of a porous body and a large number of bodies. It may be configured by a combination with a filling body, and in any case, the first feature of the method of the present invention is that the anode 1 is a porous structure, and the porous structure is By using the etching solution, all the etching solution introduced from the inlet 2 passes through the anode 1 and is discharged to the outlet 3, so that it does not flow between the electrodes or flow backward. Further, since the electrolytic oxidation reaction is sufficiently received while the liquid passes through the fine pores of the porous electrode, the reaction rate becomes high, and it works effectively especially when the concentration of the substance to be reacted is low. Therefore, even if the current is increased, the potential of the anode remains at the oxidation potential of Fe ²⁺ and Cu ⁺ , which are the reactants, and does not rise to the chlorine generation potential, so that chlorine is not generated at the same time.

Further, the electrolytic cell may be modified as shown in FIGS.

That is, in the structure shown in FIG. 3, anion exchange membranes 9A and 9B are provided at predetermined intervals on both sides of the electrolytic solution permeable anode 1 made of a porous material as in FIG. As an anode chamber 4 and cathode chambers 8A and 8B having cathodes 5A and 5B are provided on both sides thereof.

In this case, the anion exchange membranes 9A and 9B
May be continuously formed into a cylindrical shape, and the inner peripheral portion thereof may be the anode chamber and the outer peripheral portion thereof may be the cathode chamber.

Further, FIG. 4 shows a modification of the embodiment in which the liquid permeable anode 1 is formed by using the conductive filling body 10 and the power feeding body 11 as in FIG. 2, and is a pair of porous bodies. 12, 13
Are provided opposite to each other, the conductive filling body 10 is filled in the space, and the power feeding body 11 is inserted in the center thereof to form the electrolyte solution permeable anode 1, and both sides of the anode 1 are spaced by a predetermined distance. 3, the anion exchange membranes 9A and 9B are provided, the central portion is the anode chamber 4 as in FIG. 3, and the cathode chambers 8A and 8B having the cathodes 5A and 5B are provided on both sides thereof.

Also in this case, the porous bodies 12 and 13 are continuously formed into a cylindrical shape, and the inside of the porous body 12 and 13 is filled with the filling body 10 and the power feeding body 11, and the anion exchange membranes 9A and 9A are formed.
B may also be continuously formed into a cylindrical shape and arranged on the outer periphery of the cylindrical porous body of the anode 1, and the outer peripheral portion of this cylindrical anion exchange membrane may be used as the cathode chamber.

Further, the one shown in FIG.
Although the cells are arranged in series, one cell may be arranged or a large number of cells may be arranged in series or in parallel.

A second feature of the present invention is to supply an etching solution to the anode chamber 4 and a cathode electrolyte solution in which chloride is dissolved to the cathode chamber 8 while using the electrolytic bath. The pH of the electrolytic solution in the cathode chamber 8 is measured, and when the pH reaches 10, the hydrochloric acid is added to the electrolytic solution until the pH becomes 7 or less, the operation is performed within the range of pH 0 to 10, and the electrolysis is performed. When the pH of the solution is in the range of 7 to 10, the solid metal hydroxide produced by the metal ions that migrate into the electrolytic solution is filtered and separated.

Next, the second feature will be described with reference to FIG. The capacity recovery / maintenance system shown in FIG. 5 includes a pump 201 in an etching solution storage tank 200 of an etching apparatus 100.
The anode chamber inlet 2 of the electrolytic bath 300 is connected through the anode chamber outlet 3 and the anode chamber outlet 3 is connected to the etching liquid reservoir 200 through the intermediate bath 301, and the etching liquid in the etching liquid reservoir 200 is driven by driving the pump 201. Is the anode chamber 4
The etching liquid supplied to the anode chamber 4 at a necessary flow rate and regenerated by electrolytic oxidation is returned from the anode chamber outlet 3 to the etching liquid storage tank 200.

The inlet 6 and the outlet 7 of the cathode chamber 8 of the electrolytic cell 300 are connected to the cathode electrolytic solution storage tank 400 via pumps 401 and 402, and the cathode electrolytic solution storage tank 400 includes a hydrochloric acid storage tank 500. Is connected via a pump 501, and a pH meter PH is provided in the cathode electrolyte solution storage tank 400.

In the cathode electrolyte, chloride having a high concentration is dissolved so that chlorine ions consumed in the anode are supplied from the cathode electrolyte to the anode chamber 4 through the anion exchange membrane 9 at a sufficient rate. An aqueous solution is used, which is one of the features of the present invention. During electrolytic oxidation treatment, hydrogen gas is generated from the cathode, and chlorine ions migrate to the anode chamber 4 through the anion exchange membrane. The cathode electrolyte gradually shifts to the alkali side.

In the present invention, however, the pH is measured by the pH meter PH, and when the pH reaches 10, the pump 501 is driven to change the pH from the hydrochloric acid storage tank 500 to the cathode electrolyte solution tank 400. Hydrochloric acid was supplied until the pH became 7 or less to operate in the range of pH 0 to 10, and a check valve 405 between the cathode chamber outlet 7 of the electrolytic cell 300 and the cathode electrolytic solution storage tank 400 was further provided. Solenoid valve 40 on the return path
3 and a filtration path having a filter 404 are arranged in parallel, the electromagnetic valve 403 is opened to open the filtration path in the range of pH of the electrolyte solution of 7 to 10, and metal ions that migrate into the electrolyte solution are generated. The solid metal hydroxide produced was removed by filtration.

That is, the anion exchange membrane 9 selectively permeates anions, but some metal cations are
Since the anode chamber 4 is moved to the cathode chamber 8, as the operation continues, metal cations such as iron and copper increase in the cathode electrolyte and gradually deposit in a dendritic manner on the cathode 5, finally. Becomes inoperable.

As a countermeasure against this, it is conceivable to make the cathode electrolyte weakly alkaline and filter the metal cations moving to the cathode chamber 8 as a solid metal hydroxide. In this countermeasure, the anion exchange membrane 9 is used. However, there is a drawback that the metal hydroxide adheres to the cathode chamber side, which is insufficient as a measure for avoiding the problem.

However, as described above, the pH of the cathode electrolyte is 7
When the solid metal hydroxide is produced in the range of 10 to 10, the electromagnetic valve 403 is opened in association with the pH meter PH, and the filtration path having the filter 404 is opened to allow the cathode electrolyte to flow. By controlling so as to return to the cathode electrolyte storage tank 400, the metal cations moving to the cathode chamber 8 can be removed as solid metal hydroxide, and the cathode chamber of the anion exchange membrane 9 can be removed. The metal hydroxide attached to the side is dissolved and removed while the pH of the cathode electrolyte is in the range of 0 to 7.

Further, in the system shown in FIG. 5, the electrolytic bath 300 in the circulation path of the etching liquid formed between the electrolytic bath 300 and the etching liquid storage bath 200.
An oxidation-reduction potentiometer ORP is provided in the supply path to the inlet 2 and the liquid phase portion in the intermediate tank 301 to monitor the degree of recovery of the etching solution.

The degree of recovery of the etching solution can be seen from the value of the oxidation-reduction potential measured by this oxidation-reduction potentiometer ORP, that is, the ORP value, and the operation can be controlled by this ORP value. Value ORP
The value is set according to the desired etching ability, and since this ORP value changes depending on the liquid structure of the etching liquid, the necessary range may be set in advance.

By the way, since the anode 1 has a porous structure, the generation of chlorine can be suppressed. However, even if the recovery of the etching solution capacity is completed, the generation of chlorine starts when an electric current is passed. become.

In this case, however, the ORP value suddenly increases immediately before that. Therefore, the differential value of the change over time of the ORP value detected by the oxidation-reduction potentiometer ORP provided in the intermediate tank 301, that is, the change over time of the ORP value. If chlorine is generated when the rate of change is monitored to, for example, 0.22 mV / min, it is possible to detect chlorine generation in advance immediately before reaching this rate of change.

Therefore, in the system of FIG. 5, the oxidation-reduction potentiometer ORP constitutes a detecting means for detecting the generation of chlorine in the etching solution, and this detecting means, that is, the ORP value measured by the electrometer ORP changes with time. The generation of chlorine is detected in advance by the rate, and the current flowing through the electrodes 1 and 5 is interrupted or controlled to a low current value to prevent the generation of chlorine.

A chlorine detector for directly detecting chlorine may be used as the detecting means for detecting the generation of chlorine in the etching solution should chlorine be generated.

In the system shown in FIG. 5, a chlorine detector 302 is provided in the vapor phase portion of the intermediate tank 301 described above, and the current is cut off when the detector 302 detects chlorine generation.

The porous structure is constituted by any one of a combination of the porous body and a large number of packings or a combination thereof, and a catalyst for promoting electrolytic oxidation, such as iridium or ruthenium. It is preferable to coat with a catalyst composed of a platinum group metal such as platinum, palladium, platinum, or an oxide thereof.

As the chloride of the cathode electrolyte, an aqueous solution of sodium chloride, potassium chloride, calcium chloride, magnesium chloride or the like is used, but sodium chloride is preferable because it is easily available and inexpensive, and has high solubility. Further, the chloride concentration is preferably 2 to 20% by weight in order to be dissolved in the cathode electrolyte to increase the chlorine ion concentration.

[0040]

According to the invention of claim 1, the electrolytic solution permeable anode comprising the porous structure is used, and the anode chamber and the cathode chamber are partitioned by an anion exchange membrane, and chloride is dissolved in the cathode chamber. The concentration of chlorine ions is increased by using the above-mentioned aqueous solution to increase the supply rate of chlorine ions that permeate the anion exchange membrane and are supplied to the anode chamber. Furthermore, when the pH of the cathode electrolyte becomes 10, the pH becomes 7 Add hydrochloric acid until pH becomes 0 to 1
It was operated in the range of 0, and within the range of pH 7 to 10, the solid metal hydroxide produced by the metal ions that migrate into the electrolytic solution was filtered and removed to remove the solid metal hydroxide. Without decreasing the reaction rate until the concentration of ferrous chloride or cuprous chloride contained is sufficiently diluted, it is possible to recover and maintain the etching ability while suppressing the generation of chlorine gas. It is possible to prevent the deposition of the metal hydroxide and the adhesion of the metal hydroxide on the anion exchange membrane, and it is possible to use the cathode electrolyte solution stably for a long time.

Therefore, the concentration of ferrous chloride or cuprous chloride in the etching solution is maintained at a low level while continuing the etching operation by connecting to the etching apparatus as well as regenerating the aged etching solution. And as a result of this,
Efficient etching work can be continued for a long period of time using the same etching solution, which improves productivity and saves resources.

Further, according to the invention of claim 3, the problem due to chlorine generation can be solved, and according to the invention of claim 2, chlorine generation can be detected in advance, so the current value is controlled by this detection. By doing so, chlorine generation can be effectively prevented.

[0043]

【Example】

(First Embodiment) Average of 25 kg / day for 4 days (10 hours)
An etching solution storage tank containing 1400 liters of the etching solution in the process of the etching line for producing a lead frame for etching two alloys was directly connected to the etching solution capacity maintaining electrolytic cell having the same structure as that shown in FIG. The specifications of this capacity maintaining electrolytic cell are as follows. Number of unit electrolyzers arranged 10 series in series Anode 500 × 1000 mm, liquid permeability of 5 mm thickness Porous carbon plate Anode chamber 500 × 1000 mm × 70 mm Partitioned into two chambers Cathode 500 × 1000 mm 5 mm thick Impervious hard graphite plate Cathode chamber 500 mm × 1000 mm × 70 mm Ion exchange membrane Anion exchange membrane made by CYBRON CHEMICAL ORP measuring instrument One each at the inlet and outlet of the processing etching solution Density meter Installing in the etching solution storage tank Baume value 45 0.5 ± 0.5 Liquid temperature 45 ± 2 ° C pH measuring device Installed in catholyte storage tank ・ Etching liquid is supplied from the etching liquid storage tank of the etching line at a rate of 100 liters / minute, and is evenly distributed to the anode chamber of each unit Will be distributed to. The etching solution enters the ion exchange membrane side of the part partitioned by each porous anode, passes through the porous anode, enters the part on the opposite side of the ion exchange membrane, and then returns to the etching solution storage tank. The cathode electrolyte is
A 10% aqueous NaCl solution was used. Until the pH value of the catholyte solution exceeds 7 and reaches 10, the catholyte solution is passed through a filter having a filtration filter at a circulation rate of 150 l / min and returned to the catholyte solution storage tank. Further, when the pH value becomes 10, the introduction of the hydrochloric acid aqueous solution is started, and when the pH value becomes 0, the introduction is stopped. The composition of the etching solution before use is 15.
5% (ferric ion 14.7%), hydrochloric acid content 0.2%,
As the etching progresses, the nickel concentration increases. In this embodiment, the ORP value of the etching solution is 800 ±
Controlled by 30 mV vs NHE, ORP at the entrance is 770-8
The electrolysis voltage of 10 cells arranged in series in the range of 10 mV is 12
The electrolysis voltage was proportionally controlled so as to be 120 V to 0 V in the range of 0 V and 810 to 830 mV. Further, the voltage was controlled to be 0 V when the differential value of ORP was 0.22 mV / min or more. The operation was performed under the above conditions, but the ORP value set before entering the electrolytic cell from the etching solution storage tank was 8 on average.
At 12 mV, the electrolysis current is 338 A on average, and the OR at the outlet
The measured P value was 830 mV. The voltage was 105 V on average. Continue the operation while adjusting the specific gravity under the above conditions,
The operation was stopped when the net operating time reached 150 hours. During this time, the etching proceeded well at the same rate. The components of the etching solution after use were as follows. Ferric content 11.0% Ferrous content 0.2% Hydrochloric acid 0.2% Nickel content 4.4% (Second embodiment) Printed circuit for etching an average copper amount of 35 kg / day in one day (10 hours) The etching solution storage tank containing 1400 liters of the etching solution in the process of the manufacturing etching line was directly connected to the etching solution capacity maintaining electrolytic cell having the same structure as the electrolytic cell shown in FIG. In this example, a chlorine gas detector was installed on the upper part of the electrolytic cell, the maximum voltage was set to 120 V, and control was performed so that operation could be performed at the maximum voltage within which the chlorine gas was not generated. Also,
Porous titanium plate with a thickness of 2 mm, which is made by crimping titanium short fibers (diameter of about 30 microns) under heating to 10%, 90
After immersing in oxalic acid at ℃ for 3 hours, washing with water, and drying, soak 5 ml of iridium chloride and 3.4 g of butoxytantalum in a proportion of 40 ml of butanol to remove excess liquid and leave at room temperature. After drying, a porous titanium plate having a fiber surface coated with a film of iridium oxide and tantalum oxide kept at 450 ° C. was used as an anode. Other than that, when operated under the same conditions as in Example 1, the average current value was 330 A and the voltage was 92 V.
The operation was continued for about 90 hours while adjusting the specific gravity, during which the etching proceeded well at a constant rate. The components of the etching solution after use were as follows. Ferric iron content 6.8% Ferrous iron content 0.7% Hydrochloric acid 0.2% Cupric acid content 10.2% (Third example) 30 kg / day SUS 3 per day (10 hours)
A capacity-maintaining electrolytic bath having the same structure as the electrolytic bath shown in FIG. 1 was directly connected to the etching liquid storage tank containing 1400 liters of the etching liquid in the process of the lead frame manufacturing etching line for etching 04.

In this experiment, 1 was added to the exchange membrane side of the anode.
A chip of porous carbon graphite having a side of about 5 mm was filled. Further, the etching liquid was supplied from the etching liquid storage tank of the etching line at a rate of 50 liters / minute by a pump. A 10% aqueous potassium chloride solution was used as the catholyte. Other than that, when operated under the same conditions as in the first embodiment, the ORP set before entering the electrolytic cell from the etching solution storage tank
Value was 815 mV on average, the electrolysis current was 460 A on average, and the ORP measurement value at the outlet was 838 mV. The voltage was 102 V on average. Although the vehicle was operated while adjusting the specific gravity under the above conditions, the operation was stopped when the net operating time reached 160 hours. During this time, the etching proceeded well at the same rate. The components of the etching solution after use were as follows. Ferric content 11.8% Ferrous content 0.6% Hydrochloric acid 0.2% Chromium content 2.1% Nickel content 0.8% (Comparative example) In the comparative example, instead of the liquid-permeable porous carbon anode, When a liquid-impermeable hard graphite plate having a thickness of 5 mm was set in the anode chamber at an interval of 50 mm at the bottom and set in the anode chamber, a voltage of 12 was obtained.
At 0 V, the current value was 180 A. During operation, the ORP value gradually decreased, and after about 30 hours, it fell below the lower limit value of 770 mV and continued to decrease. Attempts to raise the current value beyond this were not possible because chlorine was generated.

During this period, the etching rate gradually decreased, and the etching line speed had to be greatly reduced, resulting in disturbing the etching operation.

[0046]

According to the first aspect of the present invention, the electrolyte permeable anode comprising the porous structure is used, and the anode chamber and the cathode chamber are partitioned by an anion exchange membrane, and the cathode chamber contains chloride. The chloride ion concentration is increased by using an aqueous solution in which the chlorine ion is permeated through the anion exchange membrane to increase the supply rate of chloride ions supplied to the anode chamber, and the pH of the cathode electrolyte is 1
When pH reaches 0, add hydrochloric acid until pH becomes 7 or less
Since the operation is carried out in the range of H0 to 10 and the pH is within the range of 7 to 10, the solid metal hydroxide produced by the metal ions transferred into the electrolytic solution is separated by filtration. Without reducing the reaction rate until the concentration of ferrous chloride or cuprous chloride contained in the liquid becomes sufficiently diluted,
In addition, it is possible to recover and maintain the etching performance while suppressing the generation of chlorine gas, and to prevent the deposition of metal on the cathode and the adhesion of metal hydroxide to the anion exchange membrane, thus stabilizing the cathode electrolyte for a long period of time. It can also be used.

Therefore, it is necessary to maintain the concentration of ferrous chloride or cuprous chloride in the etching solution while continuing the etching operation by connecting to the etching apparatus and regenerating the aged etching solution. As a result, an efficient etching operation can be continued for a long time using the same etching solution, and it is possible to improve the productivity and save resources.

According to the invention described in claim 3, the problem caused by chlorine generation can be solved, and according to the invention described in claim 2, since chlorine generation can be detected in advance, the current value is controlled by this detection. By doing so, chlorine generation can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing a first example of an electrolytic cell used in the method of the present invention.

FIG. 2 is a schematic cross-sectional explanatory view showing a second example of the electrolytic cell.

FIG. 3 is a schematic cross-sectional explanatory view showing a third example of the electrolytic cell.

FIG. 4 is a schematic cross-sectional explanatory view showing a fourth example of the electrolytic cell.

FIG. 5 is a block diagram showing the system of the present invention.

[Explanation of symbols]

1 Electrolyte-permeable anode 4
Anode chamber 5 Cathode 8
Cathode chamber 9 Anion exchange membrane 10
Filler PH pH meter ORP
Redox potentiometer

Claims (7)

(57) [Claims] 1. A method for recovering and maintaining the etching ability of an etching solution by electrolytically oxidizing monovalent copper ions to divalent copper ions or divalent iron ions to trivalent iron ions, An electrolytic cell having an anode chamber having an anode, a cathode chamber having a cathode, and an anion exchange membrane separating the anode chamber and the cathode chamber is used, and a porous structure is used to suppress the generation of chlorine at the anode. Using an electrolyte permeable electrode consisting of a body, while supplying an etching solution to the anode chamber and a cathode electrolyte in which chloride is dissolved in the cathode chamber, while measuring the pH of the electrolyte in the cathode chamber, When the pH becomes 10, the hydrochloric acid is added to the electrolytic solution until the pH becomes 7 or less, and the electrolytic solution is operated in the range of 0 to 10, and the pH of the electrolytic solution is in the range of 7 to 10,
A method for recovering and maintaining the ability of an etching solution, characterized in that a solid metal hydroxide produced by a metal ion that migrates into the electrolytic solution is removed by filtration. 2. A detection means for detecting the generation of chlorine in the etching solution is provided, and the detection means comprises an oxidation-reduction potentiometer for measuring the oxidation-reduction potential of the etching solution,
The method for recovering and maintaining the ability of an etching solution according to claim 1, wherein the generation of chlorine is detected in advance based on the rate of change of the oxidation-reduction potential with time measured by this electrometer. 3. The method for recovering and maintaining the ability of an etching solution according to claim 1, further comprising a detecting means for detecting the generation of chlorine in the etching solution, and controlling the current value based on the detection result of this detecting means. 4. The method for recovering and maintaining the ability of an etching solution according to claim 1, wherein the cathode electrolyte is a 2 to 20 wt% sodium chloride aqueous solution. 5. The method for recovering and maintaining the ability of an etching solution according to claim 1, wherein the porous structure comprises at least one of a porous body and a combination of a plurality of filling bodies. 6. The method for recovering and maintaining the ability of an etching solution according to claim 1, wherein the porous structure is made of carbon. 7. The method for recovering and maintaining the ability of an etching solution according to claim 1, wherein the porous structure is made of a material coated with a catalyst that promotes electrolytic oxidation.