JPH1018062A - Method for regenerating etching solution, device for regenerating etching solution and etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate an etching solution without polluting working environment. SOLUTION: An electrolytic cell 3 having anode chambers 9a, 9b and a cathode chamber 10 segmented by cation exchange membranes 8a, 8b. An aq. proton donative electrolyte soln. such as dilute sulfuric acid, is supplied to these anode chambers 9a, 9b and the etching solution contg. cupric chloride and hydrochloric acid is supplied to the cathode chamber 10. When a DC voltage is impressed between the anode chambers 9a, 9b and the cathode chamber 10 by a power source 5, copper precipitates on the cathode 11 of the cathode chamber 10 and the chlorine ions in the cathode chamber 10 forms hydrochloric acid by reacting with the hydrogen ions permeated through the cation exchange membranes 8a, 8b. As a result, the concn. of the copper ions in the etching solution decreases, the concn. of the hydrochloric acid increases and the etching liquid is regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for regenerating an etching solution, and an etching apparatus, and more particularly, to a method and apparatus for regenerating an etching solution for regenerating an etching solution containing cupric chloride and hydrochloric acid. The present invention relates to an etching apparatus employing such an etching liquid regenerating apparatus.

[0002]

2. Description of the Related Art An original plate used for gravure printing or wiring pattern printing of electronic parts generally has a predetermined pattern or wiring pattern formed by etching a copper film.

In the above-described copper film etching process for producing the original plate, a copper film on which a resist is printed is immersed in an etching solution. The etching solution used here is usually a mixed aqueous solution of cupric chloride and hydrochloric acid,
The liquid temperature is set to about 10 to 65 ° C. In such an etching step, the copper film is eroded by the action of hydrochloric acid contained in the etching solution, and copper ions are eluted from the copper film. Therefore, in the etching solution, the concentration of copper ions gradually increases, while the concentration of hydrochloric acid is decreased due to consumption of hydrochloric acid, so that the composition may change over time. The reaction at this time is represented by the following equation.

[0004]

Embedded image Cu + 2HCl → CuCl ₂ + H ₂

When the composition of the etching solution changes as described above, the etching rate becomes unstable, and the copper film is more likely to be etched in the lateral direction than in the depth direction. Such a phenomenon is referred to as a so-called side etch and causes a hindrance to precise etching of the copper film.
For this reason, in the etching step, the composition management of the etchant is regarded as extremely important, and usually, the etchant is sampled periodically to analyze the composition of the etchant, and a part or a portion of the etchant is analyzed based on the analysis result. All are discarded and new solution is replenished. However, in such a composition control, the discarded etching solution is treated as industrial waste, which may cause environmental pollution and the like.

Accordingly, various measures have been studied for electrochemically treating the etchant to regenerate the etchant having a changed composition. For example, an electrolytic method in which copper ions in an etching solution are electrochemically deposited on a cathode to thereby reduce the concentration of copper ions in the etching solution to regenerate the etching solution has been studied. The reaction in this case is represented by the following equation.

[0007]

Embedded image CuCl ₂ → Cu + Cl ₂

However, according to such an electrolytic method, a large amount of corrosive toxic chlorine gas is generated from the anode side, and there is a high risk of polluting the working environment.

An object of the present invention is to regenerate an etching solution without polluting a working environment. It is another object of the present invention to stably perform etching without contaminating a working environment.

[0010]

An etching solution regenerating method according to the present invention is a method for regenerating an etching solution containing cupric chloride and hydrochloric acid. This regeneration method includes a step of disposing an etching solution and an aqueous solution of a proton-supplying electrolyte with a cation exchange membrane interposed therebetween, and a step of performing electrolysis using the aqueous solution of the proton-supplying electrolyte as an anode and the cathode side with the etching solution side. I have.

Here, the aqueous solution of the proton-supplying electrolyte is, for example, an aqueous solution of at least one electrolyte selected from the group consisting of sulfuric acid, admisulfuric acid, boric acid, phosphoric acid, alkanesulfonic acid and alkanolsulfonic acid. .

Further, an etching liquid regenerating apparatus according to the present invention is an apparatus for regenerating an etching liquid containing cupric chloride and hydrochloric acid using a proton-supplying electrolyte aqueous solution. The regenerating apparatus comprises an electrolytic cell having an anode chamber for storing an aqueous solution of a proton-supplying electrolyte and a cathode chamber for storing an etching solution, which are partitioned by using a cation exchange membrane, an anode chamber and a cathode. And a power supply device for applying a DC voltage to the room.

An etching apparatus according to the present invention is for etching an object to be etched using an etching solution containing cupric chloride and hydrochloric acid. This etching apparatus includes an etching bath for storing an etching solution and immersing an object to be etched, an anode chamber for storing a proton-supplying electrolyte aqueous solution partitioned by using a cation exchange membrane, and an etching solution. An electrolytic cell having a cathode chamber for storing and capable of applying a DC voltage between the anode chamber and the cathode chamber; and circulating the etching solution stored in the etching bath between the cathode chamber of the electrolytic cell. And an etchant circulation path for the

[0014]

In the method for regenerating an etching solution according to the present invention, when electrolysis is performed using the aqueous solution of the proton-supplying electrolyte as an anode and the etching solution as a cathode, chlorine ions (anions) contained in the etching solution are supplied to the proton supply electrolyte. Attempts to move to the aqueous electrolyte solution side. However, since the etching solution and the aqueous solution of the proton-supplying electrolyte are disposed with the cation exchange membrane interposed therebetween, the chlorine ions are prevented from moving by the cation exchange membrane and remain in the etching solution.
Copper ions (cations) contained in the etching solution
Is precipitated by undergoing a reduction reaction in the cathode chamber. On the other hand, the proton-supplying aqueous electrolyte solution undergoes an oxidation reaction to generate oxygen gas and hydrogen ions (cations). The generated hydrogen ions pass through the cation exchange membrane and move into the etching solution, where they react with chlorine ions to become hydrochloric acid. As a result, the etchant is regenerated by increasing the concentration of hydrochloric acid at the same time as the concentration of copper ions is reduced.

In the etching liquid regenerating apparatus according to the present invention,
When a DC voltage is applied between the anode chamber and the cathode chamber by the power supply device, an electrolytic reaction proceeds between the anode chamber and the cathode chamber.
At this time, chlorine ions (anions) from the etching solution stored in the cathode chamber try to move to the anode chamber side, but are blocked by the cation exchange membrane and remain in the cathode chamber. Further, copper ions (cations) contained in the etching solution undergo a reduction reaction in the etching solution and are precipitated.
On the other hand, in the anode chamber, the proton-supplying aqueous electrolyte solution undergoes an oxidation reaction, and oxygen gas and hydrogen ions (cations) are generated. The generated hydrogen ions pass through the cation exchange membrane and move into the etching solution in the cathode chamber, where they react with chlorine ions to become hydrochloric acid. As a result, the etching solution
At the same time as the copper ion concentration decreases, the hydrochloric acid concentration increases,
Will be played.

Further, in the etching apparatus according to the present invention,
In the etching bath, the etchant used for etching the object to be etched circulates between the electrolytic bath and the electrolytic bath via an etchant circulation path. At this time, in the electrolytic cell, a DC voltage is applied between the anode chamber and the cathode chamber, and the electrolytic reaction proceeds. Here, chlorine ions (anions) generated from the etching solution stored in the cathode chamber try to move to the anode chamber side, but are prevented from moving by the cation exchange membrane and stay in the cathode chamber. Further, copper ions (cations) contained in the etching solution undergo a reduction reaction in the cathode chamber and are precipitated. On the other hand, in the anode chamber, the proton-supplying aqueous electrolyte solution undergoes an oxidation reaction, and oxygen gas and hydrogen ions (cations) are generated. The generated hydrogen ions pass through the cation exchange membrane and move into the etching solution in the cathode chamber, where they react with chlorine ions to become hydrochloric acid. As a result, the etchant is regenerated by increasing the concentration of hydrochloric acid at the same time as the concentration of copper ions is reduced. The etching solution regenerated in the electrolytic bath returns to the etching bath via the etching solution circulation path. Therefore, according to this etching apparatus,
Since the composition of the etching solution in the etching bath can be stably maintained, the object to be etched can be stably etched.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An etching apparatus according to an embodiment of the present invention will be described with reference to FIG. In the figure,
The etching apparatus 1 mainly includes an etching bath 2 for storing an etchant, an electrolytic bath 3, a storage bath 4 for storing a proton-supplying electrolyte aqueous solution, a power supply device 5, and an etching bath 2 and an electrolytic bath 3. An etchant circulation path 6 for circulating the etchant therebetween and an analyzer 7 for analyzing the etchant are provided.

The etching bath 2 is for immersing an object to be etched in an etching solution for etching. Usually, the etching bath 2 can store 250 to 300 liters of the etching solution and uses a temperature control device (not shown) to etch the etching solution. Is set in a temperature range of about 10 to 65 ° C.

The etching solution stored in the etching bath 2 is an aqueous solution containing cupric chloride and hydrochloric acid, and usually contains 110 to 180 g / l of cupric chloride (50 to 85 g / copper equivalent). l), 36% hydrochloric acid in 20 to 40 ml /
l.

On the other hand, the object to be etched is a copper film,
For example, when making an original plate for gravure printing, copper plating is applied to an iron cylinder, and a resist is printed in a predetermined pattern on the surface of the copper plating.

The electrolytic bath 3 is for regenerating the etching solution in the etching bath 2 and has a bath main body 3a. The inside of the tank body 3a is divided into three chambers by using two cation exchange membranes 8a and 8b as partition walls.
It has one anode compartment 9a, 9b and one cathode compartment 10 arranged between both anode compartments 9a, 9b. Each anode compartment 9
a and 9b have anodes 10a and 10b, respectively, and the cathode chamber 10 has a cathode 11 respectively. Here, the material of the anodes 10a and 10b is not particularly limited, but it is preferable to use a material that can be used as an oxygen generating electrode under acidic conditions. Specifically, platinum-coated titanium, platinum-group oxide-coated titanium, lead dioxide, carbon and the like can be used. On the other hand, the material of the cathode 11 is not particularly limited. However, it is preferable that the cathode 11 easily precipitates copper ions, and is inexpensive and easily available. Specifically, copper, nickel, iron, titanium, alloys thereof, stainless steel, and the like are used. However, when the copper deposited on the cathode 11 is intended to be reused, it is preferable to use copper or titanium. The anodes 10a and 10b and the cathode 11
Is not particularly limited, and may be set to various shapes such as, for example, a plate shape, a mesh shape, a perforated plate shape, and a rod shape.

The cathode 11 is installed so as to be easily attached to and detached from the cathode chamber 10, so that it can be easily replaced.

The cation exchange membranes 8a and 8b constituting the electrolytic cell 3 are not particularly limited. For example, the ion exchange groups include sulfonic acid groups, carboxylic acid groups, and phosphate groups. And a resin-based material such as a hydrocarbon-based, fluorocarbon-based, or perfluorocarbon-based resin is used. The cation exchange membrane 8
As a and 8b, those using a perfluorocarbon resin which is stable in an anodic oxidation atmosphere and has good durability are preferably used.

The storage tank 4 is a container for storing the proton-supplying aqueous electrolyte solution as described above, and has an electrolyte aqueous solution circulation path 12 between itself and the electrolytic tank 3. The electrolyte aqueous solution circulation path 12 includes a supply path 13 for supplying the proton-supplying electrolyte aqueous solution to the electrolytic cell 3 and a recovery path 14 for returning the proton-supplying electrolytic aqueous solution in the electrolytic tank 3 to the storage tank 4. ing. The supply path 13 extends from the lower part of the storage tank 4 and includes a liquid feed pump 13a. The electrolytic tank 3 side branches into two and extends into the lower parts of the anode chambers 9a and 9b, respectively. On the other hand, the collection path 14
It extends from the upper part of each of the anode chambers 9a and 9b, and the tip part is integrally arranged above the storage tank 4.

The aqueous solution of the proton-supplying electrolyte stored in the storage tank 4 is not particularly limited as long as it can generate protons by electrolysis.
It is an aqueous solution of water or at least one electrolyte selected from the group consisting of sulfuric acid, admisulfuric acid, boric acid, phosphoric acid, alkanesulfonic acid and alkanolsulfonic acid.
The electrolyte concentration of such a proton-supplying aqueous electrolyte solution is not particularly limited, but is usually 0.1 to 1
It is set in the range of 5%, preferably 0.5 to 10%.

The power supply device 5 includes the above-described anodes 10a and 10b.
This is for applying a DC voltage between the electrode and the cathode 11 and for performing the electrolysis of the etching solution in the electrolytic bath 3.

The etching solution circulation path 6 is a forward path 1 for supplying the etching solution in the etching bath 2 to the electrolytic tank 3.
5 and a return path 16 for returning the etching solution regenerated in the electrolytic bath 3 to the etching bath 2.

The outward path 15 extends from the lower part of the etching bath 2 and has a liquid feed pump 17, and the tip is disposed below the cathode chamber 10 of the electrolytic bath 3. On the other hand, return 1
Numeral 6 extends from the upper part of the cathode chamber 10 and has a liquid feed pump 18, and the tip is disposed above the etching bath 3.

The analyzer 7 is disposed in a bypass 19 connecting the forward path 15 and the return path 16 of the etching liquid circulation path 6, and includes, for example, a liquid specific gravity method, an ion electrode method, a titration method, a liquid conductivity method, This is for analyzing the copper ion concentration in the etching solution by a method such as a fluorescent X-ray method or an atomic absorption method. The analyzer 7 is connected to the power supply 5 and can operate the power supply 5 in conjunction with, for example, the concentration of copper ions in the etchant flowing through the bypass 19.

Next, the operation of the above-described etching apparatus 1 will be described. First, the outward path 1 of the etching liquid circulation path 6
5 and liquid feed pumps 1 respectively arranged in return path 16
When the actuators 7 and 18 are operated, the etching solution in the etching bath 2 flows through the outward path 15 and is supplied into the cathode chamber 10 of the electrolytic bath 3. At this time, a part of the etchant flowing in the outward path 15 branches off and flows to the bypass path 19, and the copper ion concentration is measured by the analyzer 7. The etching liquid supplied to the cathode chamber 10 flows through the return path 16, merges with the etching liquid from the bypass path 19, and returns to the etching bath 2.

On the other hand, when the liquid feed pump 13a of the electrolyte aqueous solution circulation path 12 is operated, the proton-supplying aqueous electrolyte solution in the storage tank 4 flows through the supply path 13 and flows through the anode chamber 9a,
9b, and then flows through the recovery path 14 and returns to the storage tank 4 again.

In the etching bath 2, an object to be etched is immersed in an etching solution and etched. At this time, the object to be etched is eroded by the action of hydrochloric acid in the etching solution, and elutes copper ions into the etching solution.
As a result, in the etching solution, the concentration of copper ions increases, and the concentration of hydrochloric acid decreases due to consumption of hydrochloric acid.

Such a change in the composition of the etching solution is detected by the analyzer 7. The analyzer 7 activates the power supply 5 when the copper ion concentration in the etching solution approaches a constant value, for example, 85 g / l, and activates the anodes 10a,
A DC voltage is applied between 10b and the cathode 11. The DC current density applied here may be set so that copper is deposited on the cathode 11 as described later.
It is set in the range of 0 to 50 A / dm ² .

In the cathode chamber 10 of the electrolytic cell 3 to which a DC voltage has been applied by the power supply 5, chlorine ions (anions) in the etching solution move toward the anode chambers 9a and 9b.
The movement is blocked by the cation exchange membranes 8a and 8b, and remains in the cathode chamber 10. In addition, copper ions (cations) contained in the etching solution gather toward the cathode 11, undergo a reduction reaction, and precipitate on the cathode 11.

On the other hand, in the anode chambers 9a and 9b, the proton-supplying electrolyte aqueous solution undergoes an oxidation reaction, and oxygen gas and hydrogen ions are generated from the proton-supplying electrolyte aqueous solution. The hydrogen ions (cations) generated here pass through the cation exchange membranes 8a and 8b and move into the cathode chamber 10, where they react with chlorine ions to generate hydrochloric acid.

As a result, in the etching solution in the cathode chamber 10, the concentration of copper ions is reduced while the concentration of hydrochloric acid is increased.
Will be played. The etching liquid thus regenerated flows through the return path 16 of the etching liquid circulation path 6, returns to the etching bath 2, and is used again for etching the object to be etched. For this reason, in the etching bath 2, the concentration composition of the etching solution can be kept relatively stable, so that stable etching in which side etching or the like hardly occurs can be performed.

In the regeneration of the etching solution in the electrolytic cell 3 as described above, chlorine gas is not generated as in the conventional electrolytic method, and only oxygen gas is generated from the anode chamber. Less risk of contamination. Further, the copper deposited on the cathode 11 can be recovered by replacing the cathode 11 and reused.

The above-described etching apparatus 1 can be used in a wide range of etching fields, such as for preparing a master for gravure printing and for preparing a wiring pattern master for electronic components.

[Other Examples] (1) In the above embodiment, the cathode 11 is configured to be replaceable. However, the cathode is configured to be wound, and the cathode chamber 10 is wound while being wound according to the degree of copper deposition. It can also be configured so that a new plane can be set in it.

(2) In the above-described embodiment, the power supply device 5 is operated based on the analysis result of the analysis device 7. However, the power supply device 5 is operated based on the analysis result of the analysis device 7. It can be configured to operate finely. Specifically, if the measurement result obtained by the analyzer 7 is equal to or more than a certain value, the current value of the DC voltage applied by the power supply device 5 is gradually increased according to the measurement result, and if the measurement result is less than the certain value, it is increased. The current value may be gradually lowered in response to the control so that the electrolysis of the etching solution in the electrolytic bath 3 is finely controlled.

(3) In the above embodiment, the above-mentioned electrolytic cell 3 is divided into two anode chambers 9a and 9b and one cathode chamber 10 by using two cation exchange membranes 8a and 8b. The electrolytic cell 3 may be divided into one anode chamber and one cathode chamber using one cation exchange membrane. Although the above-described electrolytic cell 3 is configured in a box shape, the electrolytic cell 3 may be formed in another shape such as a filter press type.

(4) In the above-described embodiment, the electrolytic bath 3 which is a device for regenerating an etching solution is incorporated in the etching device 1. However, the device for regenerating an etching solution is used independently of the etching device 1. Is also good.

[0043]

EXAMPLE 1 A perfluorocarbon resin sulfonic acid membrane (Nafion 32 manufactured by DuPont) was used as the cation exchange membranes 8a and 8b.
4), and the above-described etching apparatus 1 was configured using a platinum-coated titanium plate as the anodes 10a and 10b and a copper plate as the cathode 11, respectively. This etching apparatus 1
In the above, an etching solution (a cupric chloride concentration of 190 g /
1, hydrochloric acid concentration of 0.04 N) was supplied at a rate of 10 kg per hour, and a 5% aqueous sulfuric acid solution was supplied to the anode chambers 9a and 9b, and electrolysis was performed at a constant current density of 10 A / dm ² . .

As a result, the etching solution had a cupric chloride concentration of 160 g / l and a hydrochloric acid concentration of 0.48 N, and was regenerated to a level at which stable etching hardly causing side etching could be performed. By the way, when the weight change of the cathode 11 was examined one hour later, the weight increased by 280 g,
It was found that 280 g of copper had precipitated.

Example 2 As the anodes 10a and 10b, an expanded area of platinum group oxide-coated titanium having an effective area of 1.8 dm ² was used.
An etching apparatus 1 similar to that of Example 1 was configured except that a titanium plate having an effective area of 3.6 dm ² was used as the cathode 11. Note that a liquid colorimeter was used as the analyzer 7.

An etching solution having a cupric chloride concentration adjusted to 180 g / l is stored in an etching bath 2 having a liquid volume of about 400 liters to perform etching, and the etching solution is supplied at a rate of 1 liter per minute. And circulated between. On the other hand, a 5% sulfuric acid aqueous solution was stored in the storage tank 4 and circulated between the electrolytic tank 3 and the aqueous solution at a rate of 0.5 liter per minute.
The current value was set to 20 A / dm ² .

During this time, when the concentration of copper ions in the etching solution was continuously measured by the analyzer 7, it was found that the concentration was maintained in the range of 165 to 175 g / l in terms of cupric chloride. Stable etching was performed without etching.

[0048]

According to the method and apparatus for regenerating an etching solution of the present invention, the etching solution and the aqueous solution of a proton-supplying electrolyte are interposed with a cation exchange membrane interposed therebetween for electrolysis, so that the working environment is not contaminated. The etchant can be regenerated.

Further, in the etching apparatus of the present invention, since the etching solution is circulated while being regenerated in the electrolytic cell, stable etching can be performed without polluting the working environment.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an etching apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching apparatus 2 Etching bath 3 Electrolyzer 5 Power supply 6 Etch circulation path 8a, 8b Cation exchange membrane 9a, 9b Anode chamber 10 Cathode chamber

Claims (4)

[Claims] 1. An etching solution regenerating method for regenerating an etching solution containing cupric chloride and hydrochloric acid, wherein a step of arranging the etching solution and an aqueous solution of a proton-supplying electrolyte across a cation exchange membrane. And performing a process using the proton-supplying electrolyte aqueous solution as an anode and the etchant as a cathode. 2. The method according to claim 1, wherein the proton-supplying aqueous electrolyte solution is sulfuric acid,
2. The method for regenerating an etching solution according to claim 1, wherein the etching solution is an aqueous solution of at least one electrolyte selected from the group consisting of admisulfuric acid, boric acid, phosphoric acid, alkanesulfonic acid, and alkanolsulfonic acid. 3. An etching solution regenerating apparatus for regenerating an etching solution containing cupric chloride and hydrochloric acid using a proton-supplying electrolyte aqueous solution, wherein the proton is partitioned by using a cation exchange membrane. An electrolytic cell including an anode chamber for storing a supply electrolyte aqueous solution and a cathode chamber for storing the etching solution; and a power supply device for applying a DC voltage between the anode chamber and the cathode chamber. And an etchant regenerating apparatus comprising: 4. An etching apparatus for etching an object to be etched using an etching solution containing cupric chloride and hydrochloric acid, wherein said etching device stores said etching solution and immerses said object to be etched. A bath, partitioned using a cation exchange membrane, having an anode chamber for storing a proton-supplying electrolyte aqueous solution and a cathode chamber for storing the etching solution; and An etching apparatus, comprising: an electrolytic cell capable of applying a DC voltage between them; and an etchant circulating path for circulating the etchant stored in the etching bath between the cathode chamber of the electrolytic bath. .