JPH05125564A - Treatment of ferric chloride etchant containing copper - Google Patents

Abstract

PURPOSE:To close a one-step copper recovery device by diaphragm-electrolyzing a ferric chloride etchant contg. copper and using the chlorine gas generated in regenerating another etchant. CONSTITUTION:A ferric chloride etchant contg. copper is electrolyzed by a diaphragm electrolytic.cell 1. Copper is recovered in the cathode chamber wherein the ferric ion concn. is adjusted to <=30g/l and the copper ion to <=20g/l. The chlorine gas generated in the anode chamber is introduced into an absorption tower 2, another ferric chloride etchant contg. copper and used in an etching stage is introduced into the tower, and the etchant is regenerated and returned to the etching tank 3. Consequently, the etchant is efficiently regenerated, and high-purity copper is recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an etching solution containing ferric chloride containing copper, in particular, electrolytically treating the etching solution with a diaphragm, and generating chlorine gas in another etching solution. The present invention relates to a method used for the reproduction processing of.

[0002]

2. Description of the Related Art For example, when a ferric chloride solution is used as an etching solution in an etching step for forming a pattern of an integrated circuit board, the etching waste solution flowing out from the step is required to prevent environmental pollution and is economically required. It is desirable to recycle it from the
As a means for recovering copper from the waste liquid and regenerating the etching liquid, various methods have been proposed and put into practical use. And, among those methods, the etching waste liquid is electrolyzed by using an electrolytic cell divided into an anode chamber and a cathode chamber by a diaphragm, and metallic copper is deposited and recovered on the cathode side, and ferric chloride on the anode side. An electrolysis method of oxidizing and regenerating is particularly known.

In such an electrolytic method, in the etching waste liquid containing the copper plate or copper foil of the printed circuit board dissolved by etching, iron chloride and trivalent iron ions as ions from the copper substrate are added. It contains iron ions, divalent copper ions and monovalent copper ions. At the time of electrolysis of such etching waste liquid, an electrolytic reduction reaction occurs at the cathode of the electrolytic cell.

[0004]

[Chemical 1]

The reaction of [1] takes precedence, and then

[0006]

[Chemical 2]

The reaction of That is, in the liquid, first, ferric chloride is reduced to ferrous chloride, then cupric chloride is reduced to cuprous chloride, and after that, precipitation of metallic copper is first observed. Therefore, for example, when the recovery device is closed and electrolysis is performed continuously, it is said that a part of the metallic copper once deposited at the cathode, especially, the metallic copper powder dropped from the electrode into the solution is left as it is. , And reacts with FeCl ₃ or CuCl ₂ in the newly fed etching waste liquid as follows.

[0008]

[Chemical 3]

[0009]

[Chemical 4]

For this reason, the metal once deposited is dissolved again in the solution, and the recovery of copper is not desirable, and
Due to the dissolution, a considerable amount of CuCl is contained in the regenerant, which lowers the etching efficiency.

Therefore, in Japanese Patent Laid-Open No. 55-18558, in order to continuously recover copper from an etching waste liquid containing ferric chloride containing copper by electrolysis and regenerate the ferric chloride etching liquid, It is proposed to divide the reduction step into a first step from ferric chloride ions / cupric chloride ions to ferrous chloride ions / cuprous chloride ions and a second step to deposit metallic copper. ing.

[0012]

However, in the copper recovery method based on the electrolytic method disclosed in Japanese Patent Laid-Open No. 55-18558, the electrolytic reduction step is divided into two steps,
This is a method in which the etching solution is reduced until just before copper electrodeposition occurs, and there are drawbacks such as complicated equipment and difficulty in managing the solution composition. In addition, the method of treating chlorine gas, which is considered to occur naturally, is not specified, and the working environment may be deteriorated by the released chlorine gas.

In view of the above-mentioned problems in the conventional method, the present invention avoids various problems that would otherwise occur when the electrolysis process is performed in a single stage and closes the operation. Moreover, it is an object to process the etching waste liquid at a low operating cost and to safely and effectively use the generated chlorine gas without releasing it to the outside of the system.

[0014]

Means for Solving the Problems The present invention addresses the above problems by treating a ferric chloride etching solution containing copper by a diaphragm electrolysis method,
Trivalent iron ion concentration less than 30g / l, copper ion 20g / l
l Electrodeposit and collect copper in the cathode chamber adjusted to
The problem was solved by introducing the chlorine gas generated in the anode chamber to another ferric chloride etching solution containing copper used in the etching process and regenerating the solution. By adjusting the concentrations of the trivalent iron ions and the monovalent and divalent copper ions in the catholyte to be equal to or lower than the predetermined levels, it became possible to prevent the once-dissolved copper from being redissolved.

The basic concept of the present invention is to treat the etching solution by both the diaphragm electrolysis method and the chlorine gas method. In particular, all chlorine gas generated in the anode chamber of the diaphragm electrolysis is treated by the chlorine gas method. Because it is used for, there is no waste.

The chlorine gas method is described in, for example, Japanese Patent Laid-Open No.
As pointed out in Japanese Patent Publication No. 254188, conventionally, it was considered that the reproduction method was theoretically only. However, the present inventor confirmed the effectiveness of the method, and referred to in the publication, "Environmental hygiene. In particular, we have succeeded in avoiding the "problem of" by using a closed type electrolytic cell developed for this method and using an absorption tower together.

The detailed steps of the present invention will be described below.

The ferric chloride etching solution containing copper was introduced into the cathode chamber of the diaphragm electrolyzer, while adjusting the trivalent iron ion concentration in the catholyte to 30 g / l or less and the copper ion to 20 g / l or less. The step of recovering metallic copper and the liquid after the copper recovery are then introduced into the anode chamber to oxidize the contained divalent iron ions and monovalent copper ions into trivalent iron ions and divalent copper ions and chlorine. It is preferable to regenerate the etching solution by a step of generating a gas and a step of bringing the generated chlorine gas into contact with another ferric chloride etching solution containing copper to oxidize the solution.

Further, the ferric chloride etching solution containing copper is introduced into the cathode chamber of the diaphragm electrolyzer, and the trivalent iron ion concentration in the catholyte is adjusted to 30 g / l or less and the copper ion is adjusted to 20 g / l or less. While collecting the metal copper, the step of combining the solution after copper recovery with another ferric chloride etching solution containing copper, and the chlorine gas generated in the metal copper recovery step, contacting the combined solution It is also preferable to regenerate the etching liquid by the step of oxidizing the combined liquid.

The electrolytic diaphragm used in the present invention includes:
The chlorine complex of iron or copper existing in the cathode is restricted from moving to the anode side, and even if the liquid surface is slightly shaken, it has an airtightness such that the catholyte and the anolyte do not mix. As long as it has a low electric resistance, it has excellent chemical resistance, especially chlorination resistance, and the film itself does not form a bipolar electrode, it is electrically neutral, that is, it has no polarity, etc. Is required, and examples thereof include modacrylic, vinyl acetate, polyester, saran and the like.

Further, the anode in the electrolytic cell is required to have a function of lowering an overvoltage when chlorine gas is generated,
Platinum and dimentional y stable anod
e, abbreviated as DSA) RuO ₂ -Sb / Ti, IrO
_It is preferable to use _2- Pt / Ti. Copper is preferably used for the cathode. With these electrode specifications, it is possible to obtain copper crystals that are easy to peel off from the electrode plate without elution of impurities into the liquid.

[0022]

The etching solution generated in the etching bath and containing trivalent iron ions, divalent iron ions, divalent copper ions and monovalent copper ions is first introduced into the cathode chamber of the diaphragm electrolytic cell. The concentration of trivalent iron ions in the catholyte is adjusted to 30 g / l or less and the amount of copper ions is adjusted to 20 g / l or less. It is reduced to valent iron ions, and then excess divalent copper ions and monovalent copper ions are reduced and electrodeposited to recover metallic copper.

Then, the liquid having the reduced copper concentration and leaving the cathode chamber is extracted from the circulation system and introduced into the anode chamber. In the anode chamber,
Chlorine ions lose electrons and chlorine gas is generated. The chlorine gas is introduced into the absorption tower. The chlorine concentration is reduced by the generation of chlorine gas, and divalent iron ions and monovalent copper ions are electrolytically oxidized into trivalent iron ions and divalent copper ions. The liquid is extracted from the circulation system on the anode side. It is returned to the etching tank as a regeneration etchant.

The etching liquid generated in the etching tank is introduced into the absorption tower in addition to being introduced into the diaphragm electrolytic tank. By the chlorine gas generated in the diaphragm electrolyzer and guided to the absorption tower, the etching solution is

[0025]

[Chemical 5]

[0026]

[Chemical 6]

Oxidized and regenerated by the reaction formula. The regenerated cupric chloride / ferric chloride solution is returned to the etching tank as a regenerating etchant.

Further, the solution that is reduced in the cathode chamber to reduce the copper concentration and that exits the chamber may be combined with the etching liquid introduced into the absorption tower without being introduced into the anode chamber. In this case, along with the reaction in the cathode chamber, the chlorine ions that pass through the diaphragm of the electrolytic cell and move to the anode side are oxidized, and chlorine gas is generated.By introducing this to the absorption tower, the combined etching solution Will be played. The regenerated liquid is returned to the etching tank as a regeneration etchant. In this case, since a small amount of chlorine gas is generated from the anode chamber, hydrochloric acid and hydrogen peroxide may be supplementarily added and used for the oxidation regeneration of the combined etching solution.

In the present invention, chlorine gas, which has been considered to suppress the generation as much as possible in the usual electrolysis method, is positively utilized for regeneration of the etching solution in a completely sealed system.

[0030]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 In the apparatus conceptually shown in FIG.
g / l (of which monovalent copper ion 0.0g / l), iron component 100
g / l (of which divalent iron ion is 23.4 g / l), chlorine component 3
An etching solution having a composition of 17 g / l was flowed at a flow rate of 4.1 ml / min.
It is led to the cathode chamber (electrode; Cu) of the 1 V diaphragm electrolyzer 1. Copper component 13.3 g / l, iron component 104.8 g / l, chlorine component 2
With the composition of 73 g / l, the concentration of trivalent iron ions was adjusted to 30 g / l or less, and the trivalent iron ions were first converted into divalent iron ions in the cathode chamber where the circulating catholyte flowed in and out. After reduction, the excess divalent copper ions and monovalent copper ions were reduced and electrodeposited, and the deposited metal was examined. The result was that the copper component was 97.1%. The amount of recovered copper is 1
It was 7.3 g / h. The electrolytic power per 1 g of recovered copper was 3.64 Wh / g.

Then, the liquid that has reduced the copper concentration and exits the cathode chamber is extracted from the circulation system and the anode chamber (electrode; RuO ₂ -Sb / T) is used.
lead to i). In the anode chamber, chlorine ions lose electrons and generate 6.3 g / h of chlorine gas. The chlorine gas is guided to the absorption tower 2. The composition of the liquid extracted from the circulation system on the anode side by reducing the chlorine concentration by the generation of chlorine gas and electrolytically oxidizing divalent iron ions / monovalent copper ions to trivalent iron ions / divalent copper ions Was 15.7 g / l of copper component (of which monovalent copper ion was 0.0 g / l), iron component was 104 g / l (of which divalent iron ion was 0.0 g / l), and chlorine component was 247 g / l. .. The liquid is returned to the etching bath 3 as a regeneration etchant.

Generated in the etching bath 3, 37.5 g / copper component
l (of which monovalent copper ion 0.0g / l), iron component 106g / l
(Of which divalent iron ion 51.4g / l), chlorine component 24
An etching solution having a composition of 8 g / l is introduced into the absorption tower 2 at a flow rate of 2.3 ml / min. The etching solution was oxidized by the chlorine gas generated in the diaphragm electrolyzer 1 and guided to the absorption tower 2. The composition of the resulting liquid is copper component 3
7.5g / l (of which monovalent copper ion is 0.0g / l), iron component is 106g / l (of which divalent iron ion is 0.0g / l), chlorine component is 292g / l (of which dissolved chlorine amount is 11) It was 0.4 g / l). That is, it was confirmed that it was regenerated as a cupric chloride / ferric chloride solution. The liquid is returned to the etching bath 3 as a regeneration etchant.

Example 2 In the apparatus conceptually shown in FIG.
g / l (of which monovalent copper ion is 0.0 g / l), iron component 99.
An etching solution consisting of 1 g / l (of which 15.7 g / l of divalent iron ions) and 318 g / l of chlorine component is 4.6 ml / min.
First, the liquid is introduced into the cathode chamber (electrode; Cu) of the diaphragm electrolytic cell 1 having a modacrylic diaphragm and an electrolytic voltage of 2.6 V. Copper component 6.8g / l, Iron component 100g / l, Chlorine component 2
First, the trivalent iron ions are converted into divalent iron ions in the cathode chamber where the circulating catholyte flows in and out with the composition of 39 g / l and the trivalent iron ion concentration adjusted to 30 g / l or less. It was reduced, and thereafter, excess divalent copper ions and monovalent copper ions were subjected to reduction electrodeposition, and the deposited metal was examined. As a result, the copper content was 96.6%. The amount of recovered copper is 2
It was 2.7 g / h. The electrolytic power per 1 g of recovered copper was 4.58 Wh / g.

Then, the liquid having the reduced copper concentration and leaving the cathode chamber was extracted from the circulation system and joined with another etching liquid generated in the etching tank 3. Consists of a composition of copper component 36.6 g / l (of which monovalent copper ion is 0.0 g / l), iron component of 104 g / l (of which divalent iron ion is 19.3 g / l) and chlorine component of 271 g / l. Absorber 2 with the combined liquid at a flow rate of 17.3 ml / min.
Lead to.

The anode chamber of the diaphragm electrolyzer 1 (electrode; RuO ₂ −
In Sb / Ti), chlorine ions that permeate the diaphragm and move to the anode side are oxidized due to the reaction in the cathode chamber.
Chlorine gas of 1.8g / h is generated. The chlorine gas is guided to the absorption tower 2.

The combined liquid was oxidized by the chlorine gas. The composition of the resulting solution was 36.6 g / copper component.
l (of which monovalent copper ion 0.0g / l), iron component 104g / l
(Of which divalent iron ion 0.0g / l), chlorine component 292g
It was / l (of which, the amount of dissolved chlorine was 8.7 g / l). That is,
It was confirmed that it was regenerated as a cupric chloride / ferric chloride solution. The liquid is returned to the etching bath 3 as a regeneration etchant.

[0038]

As is clear from the above description,
The present invention has the following effects.

In the present invention, by adjusting the trivalent iron ion concentration and the copper ion concentration in the catholyte to be less than the predetermined values, the one-step copper recovery device, which was considered impossible in the past, was successfully closed. ..

Further, according to the present invention, since the etching solution is treated by both the diaphragm electrolysis method and the chlorine gas method, the solution can be regenerated without waste, and 90% or more high-purity copper can be recovered. it can.

Even in fields other than circuit boards, it is often necessary to convert cuprous chloride / ferrous chloride to cupric chloride / ferric chloride, which does not produce excess waste liquid and causes environmental pollution. The processing method of the present invention, which causes no problems, is extremely effective.

[Brief description of drawings]

FIG. 1 is a conceptual flow diagram according to an embodiment of the present invention.

FIG. 2 is a conceptual flow diagram according to another embodiment of the present invention.

[Explanation of symbols]

 1 diaphragm electrolysis tank 2 absorption tower 3 etching tank

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C25F 7/02 7356-4K

Claims (3)

[Claims] 1. A ferric chloride etching solution containing copper is treated by a diaphragm electrolysis method to obtain a trivalent iron ion concentration of 30 g / l or less,
Copper is recovered in the cathode chamber where the copper ion is adjusted to 20 g / l or less, and chlorine gas generated in the anode chamber is introduced to another ferric chloride etching solution containing copper used in the etching process, A method for treating an etching solution, characterized in that 2. A ferric chloride etching solution containing copper is introduced into the cathode chamber of a diaphragm electrolyzer to adjust the concentration of trivalent iron ions in the catholyte to 30 g / l or less and the copper ion to 20 g / l or less. Meanwhile, the step of recovering metallic copper and the liquid after the copper recovery is introduced to the anode chamber, and the monovalent copper ion and the divalent iron ion contained therein are added to 2
A step of oxidizing chlorine gas with trivalent iron ions and trivalent iron ions and generating chlorine gas, and a step of contacting the generated chlorine gas with another ferric chloride etching solution containing copper to oxidize the solution. The method for treating an etching solution according to claim 1, further comprising: 3. A ferric chloride etching solution containing copper is introduced into the cathode chamber of a diaphragm electrolyzer to adjust the concentration of trivalent iron ions in the catholyte to 30 g / l or less and the copper ion to 20 g / l or less. While recovering metallic copper, a step of combining the solution after copper recovery with another ferric chloride etching solution containing copper, and chlorine gas generated in the metallic copper recovery step, contacting the combined solution. And a step of oxidizing the combined solution, the method for processing an etching solution according to claim 1.