JPH07173648A - Regenerating method of etching liquid - Google Patents

Abstract

PURPOSE:To efficiently utilize an etching liquid by separating a metal to be etched from the etching liquid which is obtd. by subjecting the metal to be etched to an etching treatment and contains the metal ions to be etched and subjecting a base material to the etching treatment by using this metal to be etched. CONSTITUTION:The etching liquid 9 which is filled into a tank 5 for managing copper chloride etching and has a specific concn. of copper ions is sent to a copper chloride etching chamber 4 and is sprayed from spray nozzles 8 to a printed circuit board 6 travelling by means of rollers 7 to dissolve the exposed copper films and to form residual liquid 26. This residual liquid 26 is sent to an electrolytic dialysis device 3 and is made into a concd. copper ion liquid 19 having the high concn. of the copper ions. After this copper ion liquid is once stored in a tank 11 for managing plating, the liquid is supplied to an electrolytic copper plating tank 10. At this time, the concn. of the copper ions is measured by a copper ion concn. measuring instrument 18 where the concn. of the copper ions is measured. The concn. of the copper ions is then adjusted and the liquid is supplied to the electrolytic copper plating tank 10, where the surface of the printed circuit board 6 is subjected to the plating treatment. As a result, the etching liquid is cyclically used and the need for a waste water treatment is obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating an etching solution, and more particularly to a method for regenerating an etching solution suitable for electrolytic copper plating or electroless copper plating carried out in a printed wiring board manufacturing process.

An etching solution composed of hydrogen peroxide solution, sulfuric acid and a stabilizer thereof is used for copper plating because of the improved performance of the stabilizer, the high etching ability and the excellent economical efficiency. In recent years, it has been gradually adopted as a copper stripping solution for parts.

However, as the concentration of dissolved copper increases, this etching solution decomposes the hydrogen peroxide solution to deteriorate the stability of the etching solution or reduce the etching ability, so that a new etching solution is used. Need to be updated.

[0004]

2. Description of the Related Art For example, in a circuit forming process in the production of a printed wiring board, a copper film entirely provided on a substrate surface is provided with a resist and then selectively removed by using an etching solution. Forming a copper pattern. The etching solution used in this etching process is copper chloride solution, sulfuric acid, hydrogen peroxide solution,
And a mixture of stabilizers is commonly used.

Since the etching amount of this etching solution changes as the concentration of dissolved copper increases, it is necessary to control the concentration of copper in the etching solution to a constant value.

Conventionally, as a method of controlling the copper concentration in the etching solution to a constant value, the copper chloride etching solution is supplemented with pure water to dilute it to bring the copper concentration in the etching solution to a constant value. The method of management is adopted. Further, in the etching liquid obtained by mixing sulfuric acid with hydrogen peroxide, when the copper concentration reaches a predetermined concentration, the etching liquid is replaced with a new etching liquid, and the old etching liquid is discarded.

[0007]

As described above, in the conventional method, when the etching solution is deteriorated, the etching solution is diluted by supplementing pure water, or is replaced with a new etching solution. The method of controlling the concentration of copper in the inside was adopted.

However, in both the method of supplementing pure water and the method of replacing with a new etching solution, there is a problem that a large amount of etching solution is generated as a waste solution and the waste water must be treated. In order to perform wastewater treatment, it is necessary to provide wastewater treatment equipment, which increases the equipment cost.

Further, the generated waste liquid is uneconomical because it is not simply discarded and reused although it contains a large amount of copper ions.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for regenerating an etching solution which can realize efficient use of the etching solution.

[0011]

FIG. 1 shows the principle of the present invention.

As shown in the figure, in order to solve the above-mentioned problems, the present invention is characterized by the following means.

In the method of the present invention according to claim 1, the etching step (A1) for etching the metal to be etched with the etching solution and the etching step mixed with the metal ions to be etched are carried out by carrying out the etching step (A1). Etching metal separation step (A2) to separate the etching metal selectively, and this etching metal separation step (A2)
And a metal-to-be-etched step (A3) of plating the metal to be etched on the base material by using the metal to be etched separated and generated in step.

In the method of the second aspect of the present invention, the etching solution is mainly composed of copper chloride, hydrochloric acid, and hydrogen peroxide solution.

Further, the method of the present invention according to claim 3 is characterized in that an electrolytic dialysis method is used as a method for separating the metal to be etched in the metal to be etched separating step (A2).

Further, in the method of the present invention according to claim 4, the residual liquid from which the metal to be etched is separated in the metal-to-be-etched separation step (A2) is reused as an etching liquid in the etching step (A1). To do.

In the method of the fifth aspect of the present invention, the anode electrode used in the etching metal plating step (A3) is an insoluble electrode.

The method of the present invention according to claim 6 is characterized in that the etching solution is adjusted to be weakly acidic before the metal to be etched is separated by the electrolytic dialysis method.

Further, the invention method of claim 7 is characterized in that the etching control tank used in the etching step (A1) is configured to measure the concentration of the metal to be etched contained in the etching solution.

[0020]

The above-mentioned means operate as follows.

According to the method of the invention as set forth in claim 1, in the metal-to-be-etched separation step (A2), the metal-to-be-etched is selectively separated from the etching solution mixed with the metal-to-be-etched, and this is subjected to the metal-to-be-etched plating step. (A3)
Since the etching treatment can be carried out by utilizing the above, it is possible to recycle the etching liquid and it becomes unnecessary to perform the drainage treatment.

According to the method of the second aspect of the present invention, since a so-called copper chloride etching solution containing copper chloride, hydrochloric acid, and hydrogen peroxide as the main components is used, sulfuric acid, hydrogen peroxide, and a stable solution are used. The etching rate can be increased as compared with a sulfuric acid-based etching solution containing an agent.

According to the method of the third aspect of the present invention, since the electrolytic dialysis method is used as the method for separating the metal to be etched, the metal to be etched can be separated with simple equipment, and the separation speed can be increased. You can speed it up.

Further, according to the method of the fourth aspect of the present invention, since the residual liquid from which the metal to be etched is separated is reused as the etching liquid in the etching step (A1), the utilization efficiency of the etching liquid can be further improved. The wastewater treatment of the residual liquid after the separation of the metal to be etched becomes unnecessary.

According to the fifth aspect of the present invention, the anode electrode used in the etching metal plating step (A3) is a non-dissolving electrode, so that the occurrence of electrode deterioration can be suppressed and maintenance can be facilitated. You can

According to the method of the sixth aspect of the present invention, the dialysis membrane used in electrolytic dialysis is protected by adjusting the etching solution to a weak acidity before separating the metal to be etched by the electrolytic dialysis method. Can be planned.

Further, according to the method of the present invention, the concentration of the metal to be etched contained in the etching solution can be measured, so that the etching solution can be easily managed.

[0028]

Embodiments of the method of the present invention will now be described with reference to the drawings.

FIG. 2 is a system configuration diagram of an etching apparatus 1, a plating apparatus 2, and an electrolytic dialysis apparatus 3 to which the method for regenerating an etching solution according to an embodiment of the present invention is applied. First, the respective structures of the etching device 1, the plating device 2, and the electrolytic dialysis device 3 will be described below with reference to FIG.

The etching apparatus 1 generally comprises a copper chloride etching chamber 4 and a copper chloride etching control tank 5. Copper chloride etching chamber 4
Is a plurality of conveyance rollers 7 for conveying the member 6 to be etched (printed circuit board in this embodiment) inside thereof.
Is arranged, and the printed circuit board 6 is transported toward the right side in the drawing by the rotation of the transport roller 7.

Further, a plurality of etching spray nozzles 8 are arranged at upper and lower positions with the carrying roller 7 interposed therebetween.
The etching liquid is jetted from the plurality of etching spray nozzles 8 at a predetermined pressure. On the other hand, the printed circuit board 6 has a structure in which a copper film is formed on the entire surface by a plating device 2 described later, and then a resist is applied in a predetermined pattern.

Therefore, by moving the printed circuit board 6 in the copper chloride etching chamber 4 and spraying the etching solution onto the printed circuit board 6, the copper film other than the resist-coated portion is removed, and the copper having a predetermined pattern is removed. Electrodes are formed on the printed circuit board 6.

The copper chloride etching management tank 5 is constructed so that pure water (which functions as a diluent), hydrogen peroxide solution (which functions as an oxidizing agent), and hydrochloric acid can be mixed from a storage tank (not shown). An etching solution 9 is loaded in the copper chloride etching control tank 5. The etching solution 9 is composed of copper chloride, hydrogen peroxide solution, pure water, hydrochloric acid, and a stabilizer for suppressing decomposition of hydrogen peroxide solution. Further, copper chloride is contained in the etching solution 9 as copper (Cu
²⁺ ) and chlorine (Cl ⁺ ) ions are separated.

The etching solution 9 filled in the copper chloride etching control tank 5 is urged by a pump (not shown) to be conveyed to the copper chloride etching chamber 4 and sprayed from the etching spray nozzle 8 toward the printed circuit board 6. It When the etching solution 9 is sprayed onto the printed circuit board 6, the portion where the resist is not applied (that is,
In the area where the copper film is exposed), the following chemical reaction occurs and the copper film is etched.

CuCl ₂ + Cu → 2CuCl ₂ The cupric chloride (CuCl ₂ ) thus produced accumulates in the lower portion of the copper chloride etching chamber 4 as a residual liquid 26.

As described above, since the etching amount changes in the etching liquid 9 as the concentration of the dissolved copper increases, it is necessary to control the copper concentration in the etching liquid to a constant value. Therefore, the copper chloride etching control tank 5
Hydrogen peroxide water, pure water, and hydrochloric acid can be mixed in the chamber, and the copper concentration dissolved in the etching solution 9 can be kept constant by appropriately supplying each of them to the copper chloride etching control tank 5. Has been done.

Further, the copper chloride etching control tank 5 is provided with a copper ion concentration measuring device 17 for measuring the concentration of copper ions contained in the etching liquid 9 filled inside.

Next, the plating apparatus 2 will be described. The plating device 2 is roughly composed of an electrolytic copper plating tank 10, a plating management tank 11, a copper concentrating tank 12, and the like.

The electrolytic copper plating tank 10 is filled with a plating solution 15 inside. Further, the electrolytic copper plating tank 10 is provided with a pair of anodes 13 and a cathode 14 disposed at the center of the pair of anodes 13, and the electrodes 13 and 14 are both immersed in the plating solution 15. It has been configured. Further, a printed wiring board 6 which is a member to be plated is arranged on the cathode 14.

Copper (Cu ²⁺ ) ions and sulfuric acid (SO ₄ ²⁺ ) ions are mixed in the plating liquid 15, and each electrode 13,
By applying a predetermined potential to 14, the copper (Cu ²⁺ ) ions are attracted to the cathode 14 and deposited on the printed wiring board 6. Printed the wiring copper on the substrate 6 is of copper (Cu ²⁺⁾ ions in plating solution 15 is decreased by precipitation, copper is loaded into the plating management vessel 11 (Cu ²⁺⁾
The plating solution 15 containing a large amount of ions is supplied to the electrolytic copper plating tank 10 to replenish copper (Cu ²⁺ ) ions.

The plating control tank 11 is also provided with a copper ion concentration measuring device 18 for measuring the concentration of copper ions contained in the etching liquid 15 filled inside. Further, the plating control tank 11 is configured to be loaded with a concentrated copper ion liquid 19 in which copper ions are concentrated from the copper concentrating tank 12.

Next, the electrolytic dialysis device 3 which is a main part of the present invention will be described. The electrolytic dialysis device 3 roughly includes an electrolytic dialysis tank 20 and a Penh (PH) adjusting tank 21.

The electrolytic dialysis tank 20 has positive electrodes 22 on both sides.
A negative electrode 23 is provided, and the inside is divided into three chambers (first chamber 2
7, the second chamber 28, and the third chamber 29) are provided to define an anion exchange membrane 24 and a cation exchange membrane 25.

The residual liquid 26 is supplied to the pH adjusting tank 21 from the copper chloride etching chamber 4 described above. The residual liquid 26 that has been supplied is subjected to Penhar adjustment (PH adjustment) so as to be weakly acidic in the PH adjustment tank 21.
As described above, in the pH adjusting tank 21, P
The H adjustment is performed in the copper chloride etching chamber 4
The residual liquid 26 as it is supplied from is strongly acidic, and if it is supplied to the electrolytic dialysis tank 20 as it is, the anion exchange membrane 24 and the cation exchange membrane 25 provided therein may be destroyed. Is.

The residual liquid 26 whose pH has been adjusted in the pH adjusting tank 21 is supplied to the first chamber 27 and the second chamber 28 of the electrolytic dialysis tank 20. Here, when a predetermined potential is applied to the positive electrode 22 and the negative electrode 23 arranged in the electrolytic dialysis tank 20, chlorine (Cl ⁻ ) ions contained in the residual liquid 26 are attracted to the positive electrode 22 and copper ( Cu ²⁺ ) ions are attracted to the negative electrode 23. Further, the anion exchange membrane 24 that defines the first chamber 27 and the second chamber 28 allows passage of only anions, and the cation exchange membrane 25 that defines the second chamber 28 and the third chamber 29 is the cation exchange membrane 25. Allows only ions to pass.

Therefore, the residual liquid in the third chamber 29 becomes a liquid containing a large amount of copper ions (hereinafter, this liquid is referred to as copper concentrated ionic liquid 19). The copper concentrated ionic liquid 19 is sent to the copper concentration tank 12 of the plating apparatus 2, and the residual liquid 26 having a low copper concentration in the first and second chambers 17 and 28 is a copper chloride etching control tank of the etching apparatus 1. Sent to 5.

Next, a method for regenerating an etching solution according to the present invention, which is carried out by using the etching apparatus 1, the plating apparatus 2, and the electrolytic dialysis apparatus 3 having the above-mentioned structure, will be described.

First, before starting the etching process by the etching apparatus 1, the copper chloride etching control tank 5 is filled with an etching solution 9 having a predetermined copper ion concentration. At this time, the copper ion concentration is adjusted by appropriately charging pure water, hydrogen peroxide solution, and hydrochloric acid while observing the output of the copper ion concentration measuring device 17.

Subsequently, the etching liquid 9 loaded in the copper chloride etching control tank 5 is sent to the copper chloride etching chamber 4 and sprayed from the etching spray nozzle 8 onto the printed circuit board 6 which is the member to be etched. On the printed circuit board 6, the chemical reaction represented by the above formula occurs between the exposed copper film and the etching solution 9, and the copper film melts and dissolves in the etching solution 9 to generate the residual liquid. 26 accumulates in the lower part of the copper chloride etching chamber 4.

Since the cupric chloride contained in the residual liquid 26 has no etching action, the residual liquid 26 cannot be used as an etching liquid as it is. Therefore, conventionally, the residual liquid 26 containing a large amount of cupric chloride was treated as a waste liquid. However, this residual liquid 26
Contains a large amount of copper dissolved by the etching process. Therefore, the present embodiment is characterized in that the electrolytic dialyzer 3 is used to separate and take out a large amount of copper contained in the residual liquid 26.

The residual liquid 26 accumulated in the lower portion of the copper chloride etching chamber 4 is sent to the pH adjusting tank 21 of the electrolytic dialyzer 3 and adjusted to have a weak acidity, and then supplied to the electrolytic dialyzing tank 20. Then, by applying a potential to each of the electrodes 22 and 23, the copper ions are attracted to the negative electrode 23,
It passes through the cation exchange membrane 25 and enters the third chamber 29. Therefore, the inside of the third chamber 29 becomes the concentrated copper ion liquid 19 having a high copper ion concentration.

The above-mentioned third chamber 29 and the copper concentrating tank 12 of the plating apparatus 2 are configured so that the filled concentrated copper ion solution 19 can be circulated. By circulating it between the third chamber 29 and the third chamber 29, the concentrated copper ion liquid 19 can be made to have a predetermined concentration.

The concentrated copper ion solution 19 concentrated in the copper concentrating tank 12 is temporarily stored in the plating control tank 11 and then supplied to the electrolytic copper plating tank 10. Specifically, plating management tank 1
1 and the electrolytic copper plating tank 10, the plating solution 15 can be circulated, and when the copper ion concentration measuring device 18 determines that the copper ion concentration in the plating solution 15 has decreased, the copper concentration tank A concentrated copper ion solution 19 having a copper ion concentration higher than 12 is supplied to the plating control tank 11.

Therefore, in the electrolytic copper plating bath 10,
Even if copper is deposited on the printed circuit board 6 arranged on the cathode 14 and the copper ion concentration of the plating solution 15 is reduced, the concentrated copper ions having a higher copper ion concentration than the copper concentration tank 12 are successively passed through the plating control tank 11. Since the liquid 19 is supplied, the plating process can be continuously performed. Further, since copper ions are supplied to the electrolytic copper plating bath 10 as copper ions contained in the plating solution, an insoluble electrode (for example, a titanium electrode) can be used as the positive electrode 13, so that the positive electrode 13 is not consumed. It becomes possible to be maintenance-free. Further, the electrolytic plating has an advantage that the equipment is simple and the plating process can be performed at a relatively low cost.

Further, the first chamber 27 in the electrolytic dialysis tank 20.
And the residual liquid 26 containing less copper ions generated in the second chamber 28
Can be returned to the copper chloride etching control tank 5 and used again. That is, according to the method of the present invention, the copper ions are selectively separated from the etching solution 26 in which the copper ions are mixed, and the plating process and the etching process can be performed by using this, so that the etching solution 9 can be recycled. The need for wastewater treatment can be eliminated.

In the above-mentioned embodiments, copper (Cu) was taken as an example of the member to be etched, and an etching solution, a plating solution, etc. corresponding to this were also taken as an example. Is not limited to copper etching, but other metals such as gold (Au), chromium (C
Of course, it can be applied to the etching treatment and plating treatment such as r).

Further, in the present embodiment, when the metal to be etched (copper in this embodiment) is selectively separated from the etching solution, the copper is separated in the ion state in this embodiment. Other means may be used for this purpose, for example, the metal to be etched may be separated in the crystalline state or in the compound state.

Further, in the present embodiment, the etching liquid 9 is mainly composed of copper chloride, hydrochloric acid, and hydrogen peroxide solution, but this is because the etching speed for copper is high, and the etching speed is particularly increased. If you don't need
You may use the etching liquid of another component structure.

[0059]

As described above, according to the present invention, the following various effects are exhibited.

According to the method of the first aspect of the present invention, the metal to be etched is selectively separated from the etching liquid containing the metal ions to be etched in the metal-to-be-etched separation step, and this metal is utilized in the metal-to-be-etched plating step. Since the etching process can be performed by using the etching solution, it is possible to reuse the etching solution, and it is not necessary to perform wastewater treatment. Therefore, the equipment for the etching process can be simplified.

According to the method of the second aspect of the present invention, since a so-called copper chloride etching solution containing copper chloride, hydrochloric acid, and hydrogen peroxide as the main components is used, sulfuric acid, hydrogen peroxide, and a stable solution are used. The etching rate can be increased as compared with a sulfuric acid-based etching solution containing an agent.

According to the method of the third aspect of the present invention, since the electrolytic dialysis method is used as the method for separating the metal to be etched, the metal to be etched can be separated with a simple facility, and the separation speed can be increased. You can speed it up.

Further, according to the method of the invention of claim 4, since the residual liquid from which the metal to be etched is separated is reused as the etching liquid in the etching step, the utilization efficiency of the etching liquid can be further improved. The wastewater treatment of the residual liquid after separation of is also unnecessary.

According to the method of the fifth aspect of the present invention, by making the anode electrode used in the etching metal plating step an insoluble electrode, the occurrence of electrode deterioration can be suppressed and the maintenance can be facilitated.

According to the sixth aspect of the present invention, the dialysis membrane used for electrolytic dialysis is protected by adjusting the etching solution to be weakly acidic before separating the metal to be etched by the electrolytic dialysis method. Can be planned.

Further, according to the seventh aspect of the present invention, by providing the first concentration measuring device for measuring the concentration of the metal to be etched in the etching bath used in the etching step, the metal to be etched contained in the residual liquid is removed. Since the concentration can be measured, the etching liquid can be easily managed.

[Brief description of drawings]

FIG. 1 is a principle diagram of the method of the present invention.

FIG. 2 is a system configuration diagram of an etching apparatus, a plating apparatus, and an electrolytic dialysis apparatus to which a method for regenerating an etching solution according to an embodiment of the present invention is applied.

[Explanation of symbols]

 1 Etching device 2 Plating device 3 Electrolytic dialysis device 4 Copper chloride etching chamber 5 Copper chloride etching control tank 6 Printed circuit board (material to be etched) 9 Etching liquid 10 Electrolytic copper plating tank 11 Plating control tank 12 Copper concentrating tank 13 Anode 14 Cathode 15 Plating Solution 17,18 Copper Ion Concentration Measuring Device 19 Concentrated Copper Ion Solution 20 Electrolytic Dialysis Tank 21 PH Adjustment Tank 22 Positive Electrode 23 Anion Electrode 24 Anion Exchange Membrane 25 Cation Exchange Membrane 26 Residual Solution

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location H05K 3/18 G 7511-4E (72) Inventor Akitaka Nakayama 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited Within

Claims (7)

[Claims] 1. An etching process (A1) for etching a metal to be etched with an etching liquid (9), and an etching liquid (26) containing metal ions to be etched by performing the etching process (A1). Using the metal-to-be-etched separation step (A2) for physically separating the metal-to-be-etched and the metal-to-be-etched separated and generated in the metal-to-be-etched separation step (A2), A method of regenerating an etching liquid, comprising: an etching metal plating step (A3) of plating an etching metal. 2. The method of regenerating an etching solution according to claim 1, wherein the etching solution (9) contains copper chloride, hydrochloric acid, and hydrogen peroxide as main components. 3. The method for regenerating an etching solution according to claim 1, wherein an electrolytic dialysis method is used as a method of separating the metal to be etched in the step of separating the metal to be etched (A2). 4. The residual liquid (26) from which the metal to be etched is separated in the metal to be etched separation step (A2) is reused as the etching liquid (9) in the etching step. The method for regenerating the etching solution according to 1. 5. The method for regenerating an etching solution according to claim 1, wherein the anode electrode (13) used in the metal plating step (A3) is an insoluble electrode. 6. The method for regenerating an etching solution according to claim 3, wherein the etching solution (26) is adjusted to be weakly acidic before the metal to be etched is separated by the electrolytic dialysis method. 7. The etching control tank (17) used in the etching step (A1) is configured so that the concentration of the metal to be etched contained in the etching liquid (9) can be measured. Regeneration method of etching solution.