JPH06207281A - Treatment of waste etchant - Google Patents

Abstract

PURPOSE:To easily and economically regenerate a waste etchant generated from the etching of copper with a cupric chloride etchant. CONSTITUTION:The concn. of cuprous chloride in a waste etchant is measured, and the waste etchant is separated and supplied to the cathode compartment 32 and anode compartment 33 of an electrolytic cell 3 divided by an anion- exchange membrane 31 in the ratio corresponding to the cuprous chloride concn. Cupric chloride is electrolytically reduced to cuprous chloride in the cathode compartment 32, and the chloride ion generated by the reaction is passed through the anion-exchange membrane and transferred to the anode compartment 33. Meanwhile, cuprous chloride is electrolytically oxidized by the chloride ion in the cathode compartment 32. The amt. of chloride ion generated in the cathode compartment 32 is balanced with the amt. of chloride ion needed in the anode compartment 33 by adjusting the amt. of waste etchant to be supplied to each compartment, and hence the waste etchant is efficiently regenerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling an etching waste solution after etching a copper printed board with a cupric chloride etching solution.

[0002]

2. Description of the Related Art An etching method for a copper printed circuit board using a cupric chloride etching solution is generally widely used in a wide range of fields such as consumer use and industrial equipment. The reaction mechanism of etching copper (Cu) as the material to be etched using this etching solution is represented by the following formula (1), and cupric chloride (CuCI ₂ ) is converted to cuprous chloride (Cu) by this reaction.
Cl). Cu + CuCl ₂ = 2CuCl (1) Although this cuprous chloride has a low solubility in water and is poorly soluble, it forms a copper complex with hydrochloric acid (HCl) contained in the cupric chloride etching solution in an amount of about 7 to 8%. It is dissolved in the solution after the etching process. However, since this cuprous chloride does not have the ability to dissolve copper, the presence of this cuprous chloride in the etching solution lowers the etching rate (the amount of copper dissolved per unit time), which results in the etching of the material to be etched. Not only the efficiency of processing is significantly deteriorated, but also the etch factor is deteriorated.

Therefore, when actually performing the etching treatment, it is necessary to perform the etching treatment in a state as close as possible to a new solution, and conventionally, the cuprous chloride produced by the above-mentioned etching reaction is oxidized to quickly. A method of regenerating cupric chloride is adopted. This method includes a chemical treatment method and an electrochemical treatment method.

Among them, the chemical treatment method is, for example, hydrogen peroxide solution (H ₂ O ₂ ) is used as an oxidizing agent, and hydrochloric acid is added to supplement chlorine ions (Cl) consumed during the oxidation. By doing so, the cuprous chloride is oxidized and regenerated to cupric chloride by the reaction represented by the following formula (2). 2CuCl + 2HCl + H ₂ O ₂ = 2CuCl ₂ + H ₂ O (2) Further, the electrochemical treatment method is, for example, Japanese Patent Publication No. 63-5.
As disclosed in Japanese Patent No. 4795, in the cathode chamber of the first electrolytic cell partitioned by a diaphragm, the etching waste liquid is discharged at 5 A /
Electrolytic treatment is performed at a low current density of dm ² or less, and divalent copper ions (Cu ²⁺ ) in the etching waste liquid are converted into monovalent copper ions (Cu
⁺ )), This solution is introduced into a second electrolytic cell, and electrolysis is performed at a low current density (5 A / dm ² ) on the anode side and a high current density (5 A / dm ² ) on the cathode side, and After depositing a part of monovalent copper ions as copper (Cu) on the cathode and adjusting the specific gravity of this solution in the specific gravity adjusting tank, the solution was introduced into the anode chamber of the first electrolytic tank and was adjusted to 5 A / dm ² or less. This is a method of regenerating the cupric chloride etching solution by electrolyzing at a low current density and oxidizing monovalent copper ions in the solution into divalent copper ions.

[0005]

However, in the above-mentioned chemical treatment method, since the amount of cupric chloride in the regenerant is increased by regenerating the etchant, it is necessary to maintain the same concentration in the etchant. It is necessary to adjust by adding other reagents and water. For this reason, the amount of the etching solution after the regeneration is larger than that before the regeneration. Therefore, when an apparatus for carrying out this regeneration treatment method is connected to an etching treatment apparatus and the etching treatment and the regeneration treatment of the etching liquid are carried out continuously, the etching liquid is regenerated by the regeneration of the etching liquid as the etching treatment progresses. May overflow. For this reason, it is necessary to periodically take out the increased amount of the etching solution and dispose of it, but when disposing, it is necessary to treat the waste solution. Therefore, in this method, the more the etching treatment is performed, the more the etching liquid is constantly increased by the regenerating treatment accompanying it, and the increased etching liquid must be taken out of the system to perform the waste liquid treatment and then discarded. However, there was a problem that it was troublesome and costly.

Further, in this method, the hydrogen peroxide solution used as an oxidizing agent has a strong oxidizing action, and if it adheres to the skin of hands, feet, etc., it may cause blisters-like chemical wounds, so that it must be handled with care. Since it has the property of self-decomposing to generate pure oxygen as shown in the following formula (3), there is a risk of ignition if it is in contact with oil or the like for a long time. Therefore, there is a problem in using this chemical solution, and there is a problem that management is troublesome. 2H ₂ O ₂ = 2H ₂ O + O ₂ (3) On the other hand, the above-mentioned electrochemical treatment method is a method of suppressing the generation of chlorine gas in the anode part, which has been a problem in the conventional electrochemical treatment method. For this reason, this method uses three tanks, a first electrolytic tank for adjusting the oxidation-reduction potential of the etching waste liquid, a second electrolytic tank for recovering copper, and a specific gravity adjusting tank for adjusting specific gravity. The current densities of the anode and the cathode in the first and second electrolytic cells are controlled. Therefore, in carrying out this method,
After the treatment liquid is introduced into the cathode part of the electrolytic cell partitioned by the diaphragm and subjected to the reduction treatment, the treatment liquid is subsequently subjected to the oxidation treatment in the anode chamber, so that the current efficiency tends to be deteriorated.
Since one electrolysis cell and a pump and a flow path that connect each electrolysis cell are required, the overall system is large and complicated, and in order to maintain these balances, the current efficiency must be lowered as a whole to operate. There is a problem that it is necessary (otherwise, chlorine gas is generated in the anode part).

The present invention has been made under the above circumstances, and an object thereof is to provide an etching waste liquid treatment method capable of easily and economically regenerating the etching liquid after the etching treatment. To do.

[0008]

The present invention relates to a method of regenerating an etching liquid from an etching waste liquid after copper is etched using a cupric chloride etching liquid, in which an electrolytic cell is provided with a cathode chamber using an anion exchange membrane. And the anode chamber, and the electrolysis is performed by separately supplying the etching waste liquid to the cathode chamber and the anode chamber according to the ratio of the supply amount according to the cuprous chloride concentration of the etching waste liquid.

[0009]

[Function] Measuring the cuprous chloride concentration in the etching waste liquid,
The etching waste liquid is dividedly supplied to the cathode chamber and the anode chamber of the electrolytic cell partitioned by the anion exchange membrane according to the ratio of the supply amount according to the concentration of cuprous chloride. In the cathode chamber, electrolytic reactions of reduction reaction of cupric chloride to cuprous chloride in the etching waste liquid and reduction deposition reaction of cuprous chloride to copper proceed, and chlorine ions generated by this reaction are It passes through the anion exchange membrane and moves to the anode chamber. On the other hand, in the anode chamber, an oxidation reaction of chloride from cuprous chloride to cupric chloride in the etching waste liquid proceeds. Here, the amount of chlorine ions generated in the cathode chamber and the amount of chlorine ions required in the anode chamber are balanced by adjusting the amount of the etching waste liquid supplied to each electrolytic chamber, so that etching is performed efficiently. The waste liquid is recycled.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The etching waste liquid treatment method of the present invention will be described below with an apparatus for carrying out this method. FIG. 1 is a configuration diagram of an etching waste liquid treatment apparatus for carrying out the present invention. Figure 1
A medium 1 is a waste liquid storage tank for storing an etching waste liquid after etching with a material to be etched such as a copper printed board and a cupric chloride etching liquid. The waste liquid storage tank 1 includes a pump 11 and a chloride chloride A circulation path A for circulating the etching waste liquid to the waste liquid storage tank 1 via the one-copper concentration meter 12 is provided. The cuprous chloride concentration meter 12 measures the cuprous chloride concentration in the etching waste liquid, and is measured by, for example, a method of detecting the cuprous chloride concentration in the solution by an absorptiometry method. .

A supply path B is branched from between the pump 11 and the cuprous chloride concentration meter 12 in the circulation path A, and the supply path B is further divided into two supply paths C and D. The supply path C is connected to one end side of the cathode chamber 32 of the electrolytic cell 3 via the flow meter 21 and the flow rate adjusting valve 23, while the supply path D is provided.
Is connected to one end side of an anode chamber 33 of the electrolytic cell 3 via a flow meter 22 and a flow rate adjusting valve 24.

The electrolytic cell 3 is a cell divided into a cathode chamber 32 and an anode chamber 33 by an anion exchange membrane 31. The cathode chamber 32 is provided with a cathode 34, and the anode chamber 33 is provided with an anode 35. . As the material of the cathode 34, for example, soft iron, stainless steel, copper or the like is suitable because the cathode 34 is negatively polarized and protected against corrosion during energization. Also, as the material of the anode 35, corrosion resistance is required, and thus, for example, Clafite. ,
Carbon, insoluble anode, etc. are suitable. When an insoluble anode is used, it is preferable to use one having a high catalytic activity with a suitable chlorine voltage.

A supply path E is provided at the other end of the cathode chamber 32 and a supply path F is provided at the other end of the anode chamber 33 in the electrolytic cell. The supply path F is supplied midway. It joins the channel E and is connected to the regeneration liquid tank 4.

Further, in this embodiment, the cuprous chloride concentration meter 1
The control means 5 for controlling the amount of the etching waste liquid supplied to the cathode chamber 32 and the anode chamber 33 by controlling the opening and closing of the flow rate adjusting valves 23 and 24 based on the output signal of 2 or the cuprous chloride concentration in the solution. It is provided.

Next, the operation of the above embodiment will be described. In an etching reaction tank (not shown), for example, a copper printed board is subjected to etching treatment with the cupric chloride etching solution represented by the formula (1) described in the section of (Prior Art), and the waste liquid after the etching treatment ( The etching waste liquid) is stored in the waste liquid storage tank 1 and is circulated through the circulation path A by the operation of the pump 11. The etching waste liquid contains cupric chloride, which is an etching product, and unreacted cupric chloride, and the cuprous chloride concentration meter 12 in the middle of the circulation path A uses the chloride chloride in the etching waste liquid. The copper concentration is measured, and this measured value is output to the control means 5.

An operation signal is output from the control means 5 to the flow rate adjusting valves 23 and 24 based on the measured value of the cuprous chloride concentration, and the etching waste liquid in the waste liquid storage tank 1 is pumped to the supply path B. It is supplied to the cathode chamber 32 of the electrolytic cell 3 through C, the flow meter 21, and the flow rate adjusting valve 23, and similarly, the supply path D, the flow meter 21, and the flow rate adjusting valve 24
Is supplied to the anode chamber 33 via.

In the cathode chamber 32, the following (4) is caused by electrolysis.
A reduction reaction from cupric chloride to cuprous chloride shown in the formula and a reduction deposition reaction of copper shown in the formula (5) occur, copper is deposited on the cathode 34, and chlorine ions (Cl ⁻ ) are anion-exchanged. It passes through the membrane 31 and moves to the anode chamber 33. Further, in the anode chamber 33, as shown in the following formula (6), an oxidation reaction from cuprous chloride to cupric chloride occurs, and cupric chloride is regenerated. CuCl ₂ + e ⁻ → CuCl + Cl ⁻ (4) CuCl + e ⁻ → Cu + Cl ⁻ (5) CuCl + Cl ⁻ → CuCl ₂ + e ⁻ (6) By the above electrolysis reaction, the outlet side of the cathode chamber 32, that is, the supply path E is The solution on the side provided is a hydrochloric acid solution containing almost no monovalent copper ions, and the solution on the outlet side of the anode chamber 33, that is, the side on which the supply path F is provided, contains almost no monovalent copper ions. Becomes cupric chloride solution. Then, the regenerated cupric chloride solution is supplied from the anode chamber 33 to the regeneration solution tank 4 via the supply passage F, and the hydrochloric acid solution is also supplied from the cathode chamber 32 to the supply passage F via the supply passage E, It is supplied to the regenerator tank 4 together with the cupric chloride solution through the supply channel F.

In this electrolytic reaction, the area of the anode 35 is larger than that of the cathode 34, but the reason that the areas of the electrodes are different is that substances reacting at the electrodes are different and unnecessary. This is to suppress such a reaction. That is, when a constant current is applied to the electrolytic cell, changing the area of the electrode changes the apparent overvoltage at the electrode, and increasing the area of the electrode decreases the current density per unit area. The electric potential becomes low. On the other hand, when the area of the electrode is reduced, the current density per unit area increases and the electrode potential increases.

When the electrode potential increases, at the cathode 34, a reaction of depositing cuprous chloride as copper metal and a reaction of reducing cupric chloride to cuprous chloride occur together with a hydrogen gas generation reaction, and the anode 34 In 35, a reaction of oxidizing cuprous chloride to cupric chloride and a reaction of oxidizing chlorine ions to chlorine gas occur. Since this hydrogen gas or chlorine gas generation reaction is a loss when viewed from the electric power supplied, it is necessary to change the electrode potential by changing the area of the electrode and suppress this loss, that is, unnecessary reaction. Regarding the cathode 34, if the electrode potential is lowered too much, the copper precipitation reaction does not occur, so it is necessary to appropriately adjust the size of each electrode in consideration of these. So, for example, in this embodiment,
The area of the anode 35 is set larger than that of the cathode 34 with the area of the cathode 34 being 1 and the area of the anode 35 being 5.

Further, in this electrolytic reaction, in order to suppress the generation of chlorine gas in the anode chamber 33, the amount of the etching waste liquid supplied to the cathode chamber 32 and the anode chamber 33 is adjusted by the flow rate adjusting valves 23 and 24. The supply amount of the cuprous chloride in the etching waste liquid is adjusted so that the amount of chlorine ions transferred from the cathode chamber 32 to the anode chamber 33 and the amount of cuprous chloride supplied to the anode chamber 33 are balanced. It is decided based on. That is, for example, when the composition of the etching waste liquid is cuprous chloride concentration 2.4% and cupric chloride concentration 19.4%, and the total amount of the etching waste liquid is 1008 kg, the etching waste liquid supplied to the cathode chamber 32. Is defined as x%, the amount of chlorine ions generated in the cathode chamber 32 is equal to the amount of chloride ions generated when cuprous chloride is reduced to copper (x% × 2.4% × 1008 / chloride). Cuprous molecular weight kmol) and amount of chloride ions generated when cupric chloride is reduced to copper through cuprous chloride (x% × 1)
9.4% x 1008 g x 2 / cupric chloride molecular weight km
ol), and the amount of chlorine ions required for the oxidation of cuprous chloride in the anode chamber 33 is (10
0-x)% x 2.4% x 1008 / cuprous chloride molecular weight kmol. In order to suppress the generation of chlorine gas in the anode chamber 33, both may be made equal, and the result is x = 7.19%. Therefore, in this case, the cathode chamber 32
The ratio of the amount supplied to the anode chamber 33 to the amount supplied to the anode chamber 33 is 7:93.
Becomes The concentration of cupric chloride in the etching waste liquid can be determined based on the concentration of cuprous chloride.

Further, in the etching waste liquid treatment apparatus of this embodiment, the electrolytic bath 3 is provided with an anion exchange membrane 3 having ion selectivity.
Since the cathode chamber 32 and the anode chamber 33 are partitioned by using 1, the chloride ions which are anions from the cathode chamber 32 selectively pass through the anion exchange membrane 31 and move to the anode chamber 33,
In the anode chamber 33, cupric chloride is regenerated by the reaction between the chloride ions transferred as described above and cuprous chloride.

Considering the case where the electrolytic cell 3 of this embodiment is partitioned by a diaphragm, since the diaphragm does not have ion selectivity, not only chlorine ions but also monovalent copper ions and divalent copper ions can be separated. It passes through and goes back and forth between the cathode chamber 32 and the anode chamber 33. Therefore, the cathode chamber 32 and the anode chamber 33
Even if the amount of the etching waste liquid supplied to the anode chamber is adjusted, the concentration of the ions contained in each electrolytic chamber changes due to the movement of each ion and the amount of chlorine ions transferred from the cathode chamber 32 to the anode chamber 33 and the anode chamber 33. At 33, the chlorine ions needed are out of balance. Therefore, it is presumed that an unnecessary reaction such as a hydrogen gas generation reaction in the cathode chamber 32 or a chlorine gas generation reaction in the anode chamber 33 occurs, and the electrolytic reaction for regenerating the etching solution cannot be efficiently performed.

Furthermore, in the etching waste liquid treatment apparatus of this embodiment, the etching waste liquid supplied to the cathode chamber 32 passes through or circulates only in the cathode chamber 32, and the anode chamber 3
Since the etching waste liquid supplied to No. 3 passes or circulates only in the anode chamber 33, the cathode chamber 32 and the anode chamber 33.
Each electrode reaction that occurs in 1 can be effectively used without loss.

Therefore, according to the above embodiment, since the cupric chloride etching solution is regenerated by the electrochemical treatment method of the etching waste solution, the etching solution can be regenerated without changing the amount of the etching solution. It is not necessary to treat the increased amount of etching liquid after regeneration, which was a problem with conventional chemical treatment methods, and it is easy and safe because it does not require an oxidizing agent such as hydrogen peroxide. The etching solution can be regenerated.

Further, according to this embodiment, the electrolytic cell 3 is partitioned by the anion exchange membrane 31, and the amount of the etching waste liquid supplied to the cathode chamber 32 and the anode chamber 33 is based on the cuprous chloride concentration in the etching waste liquid. Since the etching solution can be efficiently regenerated by suppressing the generation reaction of chlorine gas in the anode chamber 33, the two electrolytic cells and the specific gravity required in the conventional electrochemical treatment method can be obtained. Even if the adjusting tank is not used, the etching liquid can be easily regenerated by a simple device.

Here, an example of an experiment conducted to confirm the effect of the etching waste liquid treatment apparatus of this embodiment will be described. For example, the composition is copper 100 kg (10%), cupric chloride 211.58 kg (21%), hydrochloric acid 70.00 kg.
(7%) and 718.42 kg (71%) of water, the composition of the etching waste liquid after etching copper using a total amount of 1000 kg of cupric chloride etching liquid is 24. 32 kg (2.41%), cupric chloride 195.07 kg (19.36%), hydrochloric acid 7
0.00 kg (6.95%), water 718.42 kg (7
1.29%), and this etching waste liquid is stored in the cathode chamber 32.
To the anode chamber 33 at a flow rate of 7:93, and in the electrolytic cell 3, the cell voltage was 5.0 V, the anode area per electrolytic cell was 0.5 m ² , and the anode current density was 40.
The electrolysis reaction was carried out under the conditions of 0 A / m ² , an energizing current of 200 A, a number of cells of 31 and a required amount of electricity of 6.1 KAH (kilo ampere hour). Then, the composition of the solution flowing out from the cathode chamber 32 after the electrolytic reaction was measured and found to be 5.07 kg (0.08879%) of hydrochloric acid and 52.01 kg of water.
The composition of the solution flowing out from the anode chamber 33 is 0.00 kg (0.00%) of cuprous chloride, 21 cupric chloride.
1.58 kg (22.44%), hydrochloric acid 64.93 kg
(6.89%), water 666.40 kg (70.67%)
Met. Therefore, the composition of the regenerated solution (the solution flowing out from the cathode chamber 32 + the solution flowing out from the anode chamber 33) stored in the regeneration liquid tank 4 is 211.58 kg (2
1.16%), hydrochloric acid 70.00 kg (7.00%), water 718.42 kg (71.84%), and the composition and the solution amount were almost the same as the initial cupric chloride etching solution. Therefore, in this etching waste liquid treatment device,
It was confirmed that the etching waste liquid was efficiently regenerated without increasing the amount of the solution.

In the above, the etching waste liquid treatment apparatus of the present invention can also be applied to the case where the etching waste liquid is intermittently supplied to the electrolytic cell to perform the regeneration treatment.

[0028]

EFFECTS OF THE INVENTION According to the present invention, an etching waste liquid obtained by etching copper with a cupric chloride etching liquid is placed in an electrolytic cell in which a cathode chamber and an anode chamber are partitioned by an anion exchange membrane. , The electrolytic treatment is performed while the amount of the etching waste liquid supplied to the cathode chamber and the anode chamber is adjusted according to the concentration of cuprous chloride in the etching waste liquid, and the cupric chloride etching liquid is regenerated, so a regeneration treatment step In addition, since the amount of the etching liquid is not increased by the regeneration process, the waste liquid treatment for the increased amount of the etching liquid is not required, and the etching waste liquid can be efficiently regenerated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an etching waste liquid treatment apparatus for carrying out an etching waste liquid treatment method of the present invention.

[Explanation of symbols]

 1 Waste Liquid Storage Tank 21, 22 Flow Meter 23, 24 Flow Control Valve 3 Electrolysis Tank 31 Anion Exchange Membrane 32 Cathode Chamber 33 Anode Chamber 34 Cathode 35 Anode 4 Regeneration Liquid Tank 5 Control Means

Claims (1)

[Claims] 1. A method of regenerating an etching liquid from an etching waste liquid after etching copper with a cupric chloride etching liquid, wherein an electrolytic cell is divided into a cathode chamber and an anode chamber by an anion exchange membrane, An etching waste liquid treatment method, characterized in that the etching waste liquid is dividedly supplied to the cathode chamber and the anode chamber for electrolysis according to the ratio of the supply amount of the etching waste liquid according to the cuprous chloride concentration.