Regeneration method of removal liquid and regenerated removal liquid

Abstract

The regeneration method of the stripping solution comprises: when a printed wiring board is manufactured by a semi-additive method, a process of removing the nickel-chromium-containing layer from a substrate having a nickel-chromium-containing layer and a copper-containing layer using the stripping solution; a process of recovering the used stripping solution; and a process of contacting the stripping solution recovered in the recovery process with a chelating resin, wherein the chelating resin has a functional group represented by the following formula (1). In formula (1), a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbon atoms. A portion of the hydrogen atoms possessed by the hydrocarbon group may be substituted by halogen atoms. [Chemical Formula 1]#imgabs0#

Description

Technical Field

[0001] The present disclosure relates to a method for regenerating a removal liquid and a regenerated removal liquid.

[0002] This application claims priority based on Japanese application No. 2020-194326 filed on November 24, 2020, and cites all the contents described in the Japanese application. Background Art

[0003] As electronic devices become smaller and lighter, the wiring part of a printed wiring board has been miniaturized. As a method for miniaturizing the wiring part of a printed wiring board, for example, a seed layer is formed on the surface of an insulating resin layer, a plating resist is used to cover the portion other than the portion where the circuit is formed, and then a metal layer is selectively formed only on the circuit portion by electroplating. Furthermore, after removing the plating resist, the seed layer other than the circuit portion is removed by using a seed layer removing solution to form a printed wiring board (see Japanese Patent Publication No. 2004-6773).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-6773 Summary of the invention

[0007] The regeneration method of the removing solution disclosed in the present invention comprises: when a printed wiring board is manufactured by a semiadditive process, a step of removing the nickel-chromium containing layer from a substrate having the nickel-chromium containing layer and the copper containing layer using the removing solution; a step of recovering the used removing solution; and a step of contacting the removing solution recovered in the recovering step with a chelating resin, wherein the chelating resin has a functional group represented by the following formula (1).

[0008] [Chemical formula 1]

[0009]

[0010] (In formula (1), a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbon atoms. A portion of the hydrogen atoms in the hydrocarbon group may be substituted with a halogen atom.) DETAILED DESCRIPTION

[0011] [Problems to be Solved by the Invention]

[0012] For example, in the manufacture of printed wiring boards, a seed layer is formed on a substrate, and a copper plating layer or the like is stacked thereon. As the seed layer, there is, for example, a layer containing nickel and chromium. Such a seed layer is partially removed during the manufacturing process, but a nickel-chromium containing layer removing liquid is usually used for the removal. The nickel-chromium containing layer removing liquid is a liquid for removing the nickel-chromium containing layer. Hereinafter, it is sometimes referred to as the removing liquid. Such a removing liquid cannot be reused. The reason is that when the seed layer is immersed in the removing liquid, the metal components of other layers of the printed wiring board will dissolve in the removing liquid, the metal concentration in the removing liquid will increase, and as a result, the etching performance will be reduced.

[0013] In particular, in a fine printed wiring board, a reduction in etching performance causes peeling of wiring portions, which in turn affects the performance of the circuit board.

[0014] The present disclosure has been made based on the above circumstances, and an object of the present disclosure is to provide a method for regenerating a removing liquid that can extend the life of the removing liquid and obtain a regenerated removing liquid that can suppress peeling of a wiring portion when used in the manufacture of a printed wiring board.

[0015] [Effects of the present disclosure]

[0016] According to the present disclosure, it is possible to produce a regenerated removing liquid that can extend the life of the removing liquid and suppress peeling of a wiring portion when used in the manufacture of a printed wiring board.

[0017] [Description of Embodiments of the Present Disclosure]

[0018] First, embodiments of the present disclosure are listed and described.

[0019] The regeneration method of the removing solution disclosed in the present invention comprises: when a printed wiring board is manufactured by a semi-additive process, a step of removing the nickel-chromium containing layer from a substrate having the nickel-chromium containing layer and the copper containing layer using the removing solution; a step of recovering the used removing solution; and a step of contacting the removing solution recovered in the recovery step with a chelating resin, wherein the chelating resin has a functional group represented by the following formula (1).

[0020] [Chemical formula 2]

[0021]

[0022] (In formula (1), a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbon atoms. A portion of the hydrogen atoms in the hydrocarbon group may be substituted with a halogen atom.)

[0023] The removing solution used to remove the nickel-chromium containing layer usually contains hydrochloric acid, sulfuric acid, etc. In addition to nickel and chromium, the copper contained in the wiring portion is also dissolved in such a removing solution to some extent. When the concentration of copper ions in the liquid increases, the dissolution rate of copper is further accelerated. Therefore, the life of the removing solution is determined by the concentration of copper ions in the removing solution. The inventors believe that in order to achieve the long life of the removing solution and the suppression of the stripping of the manufactured circuit, it is necessary to keep the concentration of copper ions in the removing solution low, and have conducted in-depth research. It was found that by contacting the removing solution with a chelate resin having a functional group represented by the above-mentioned formula (1), the copper ions in the removing solution can be adsorbed on the chelate resin. In the regeneration method of the removing solution, after the semi-addition process of removing the above-mentioned nickel-chromium containing layer, the used removing solution is recovered and contacted with a chelate resin having a functional group represented by the above-mentioned formula (1). Thus, the concentration of copper ions in the removing solution after the above-mentioned regeneration is reduced. Since the copper ion concentration of the regenerated removing solution is reduced, the removal effect of the nickel-chromium containing layer can be improved, and the dissolution of copper contained in the wiring portion in the process of removing the nickel-chromium containing layer can be suppressed. As a result, peeling of the wiring portion can be suppressed.

[0024] The functional group is preferably a bis(2-pyridylmethyl)amino group. Since the chelate resin has the functional group represented by the formula (1), the removal effect of the nickel-chromium containing layer can be further improved.

[0025] In addition, it is preferred that the regeneration removal liquid according to another embodiment of the present disclosure is a regeneration removal liquid for a semi-additive method obtained by the regeneration method, and contains a pyridine compound, and the concentration of the pyridine compound exceeds 0 ppm and is 5000 ppm or less. Such a regeneration removal liquid has a good effect of removing the nickel-chromium containing layer.

[0026] In addition, it is preferred that the regeneration removal solution further contains chloride ions and copper ions, has a pH of 1 or less, and has a copper ion concentration of 1 ppm or more and 2000 ppm or less. Such a regeneration removal solution can further improve the removal effect of the nickel-chromium containing layer.

[0027] [Details of the embodiments of the present disclosure]

[0028] Hereinafter, a method for regenerating a removing solution and a regenerated removing solution according to an embodiment of the present disclosure will be described in detail.

[0029] <Regeneration Method of Removal Solution>

[0030] The regeneration method of the removing solution disclosed in the present invention comprises: when a printed wiring board is manufactured by a semi-additive process, a process of removing the nickel-chromium containing layer from a substrate having the nickel-chromium containing layer and the copper containing layer using the removing solution; a process of recovering the used removing solution; and a process of contacting the removing solution recovered in the above recovery process with a chelate resin, wherein the chelate resin has a functional group represented by the following formula (1). "The process of removing the nickel-chromium containing layer from a substrate having the nickel-chromium containing layer and the copper containing layer using the removing solution" is sometimes referred to as "the process of removing the nickel-chromium containing layer". "The process of recovering the used removing solution" is sometimes referred to as "the process of recovering the used removing solution". "The process of contacting the removing solution recovered in the above recovery process with a chelate resin" is sometimes referred to as "the process of contacting the recovered removing solution with a chelate resin".

[0031] [Chemical formula 3]

[0032]

[0033] (In formula (1), a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbon atoms. A portion of the hydrogen atoms in the hydrocarbon group may be substituted with a halogen atom.)

[0034] (Step of removing the nickel-chromium containing layer)

[0035] This process is carried out in the manufacturing process of the printed circuit board using the semi-additive method. The substrate having the nickel-chromium containing layer and the copper containing layer is not particularly limited as long as it contains at least the nickel-chromium containing layer and the copper containing layer. The substrate is a substrate in the manufacturing process of the printed circuit board using the semi-additive method. Such a substrate is manufactured, for example, by the following method.

[0036] First, prepare a base film. Examples of the base film include polyimide, polyethylene terephthalate, liquid crystal polymer, fluororesin, etc. A nickel-chromium-containing layer is stacked thereon. Examples of stacking methods include electroless plating, sputtering, vapor deposition, coupling agent coating, etc. A conductive layer containing copper is stacked on the nickel-chromium-containing layer. Examples of stacking methods for the conductive layer include electroless plating, coating, drying and sintering of a metal particle dispersion in which metal particles are dispersed, sputtering, vapor deposition, etc. Next, a resist film having an opening corresponding to a wiring pattern is stacked on the conductive layer. Examples of stacking methods for the resist film include a method of coating and drying a liquid resist composition, a method of thermally pressing a sheet-like resist composition, etc. The sheet-like resist composition is, for example, a dry film. Next, a copper plating layer is formed on the conductive layer exposed from the opening of the resist film. Then, the resist film is removed. The resist film can be removed by a known removal solution containing 2-aminoethanol, tetramethylammonium hydroxide, an organic acid, etc. as a main component, for example. Then, the conductive layer exposed by removing the resist film is removed. The conductive layer can be removed by using, for example, a sulfuric acid-hydrogen peroxide aqueous solution. The sulfuric acid-hydrogen peroxide aqueous solution is sometimes referred to as a Piranha solution.

[0037] The substrate obtained in this way is a substrate including at least a nickel-chromium containing layer and a copper containing layer on a base material.

[0038] Next, the nickel-chromium containing layer is removed from the substrate having the nickel-chromium containing layer and the copper containing layer using a removing solution. Here, the nickel-chromium containing layer is removed by dissolving using a removing solution that corrodes nickel and chromium. As a method of dissolving, for example, the removing solution is contained in a liquid tank, and the substrate is immersed in the removing solution.

[0039] The unused removing solution preferably contains chloride ions and has a pH of 1 or less. The removal effect of the nickel-chromium containing layer can be further improved by removing the nickel-chromium containing layer under the strongly acidic condition that the pH of the removing solution is 1 or less. As the strong acid component, hydrochloric acid is preferred, and specifically, a hydrochloric acid aqueous solution having a concentration of 5 mass % or more and 20 mass % or less is preferred.

[0040] As the removing liquid used, an unused removing liquid or a regenerated removing liquid described below may be used, or an unused removing liquid, a regenerated removing liquid, and a used removing liquid may be used in any combination.

[0041] In the step of removing the nickel-chromium containing layer, the nickel-chromium containing layer is dissolved and removed.

[0042] (Process for recovering the used removal liquid)

[0043] In this process, the above-mentioned used removing solution (hereinafter also referred to as used removing solution) is recovered. Since the copper of the copper-containing layer is dissolved, the copper ion concentration in the used removing solution is higher than that of the unused removing solution. When the concentration of copper ions in the removing solution increases, the dissolution rate of copper is further accelerated. Therefore, the life of the removing solution is determined by the concentration of copper ions in the removing solution. Therefore, after the process of obtaining the used removing solution involved in the present disclosure, a process of measuring the copper ion concentration of the used removing solution can be arbitrarily included. When the result of the measurement is that the concentration of copper ions is lower than a predetermined concentration, it can be directly reused. On the other hand, when the concentration of copper ions is higher than a predetermined concentration, the removing solution can be regenerated in the next process. It should be noted that in the process of recovering the removing solution of the nickel-chromium containing layer, the above-mentioned removing solution is recovered.

[0044] (Step of contacting the recovered removal solution with a chelating resin)

[0045] In this step, the used removal solution recovered in the above-mentioned recovery step is brought into contact with a chelating resin, thereby regenerating the used removal solution.

[0046] Above-mentioned chelate resin has the functional group represented by following formula (1).By making the removing solution contact with this chelate resin, can adsorb the cupric ion in the removing solution, therefore can keep the concentration of cupric ion of the regenerated removing solution of gained lower.Thus, can when prolonging the life-span of the removing solution, make the removal effect of nickel-chromium containing layer good, and can suppress the dissolving of the copper contained in the wiring portion in the operation of removing nickel-chromium containing layer.In addition, even under the situation of manufacturing fine printed wiring board, also can suppress the stripping of wiring portion.

[0047] [Chemical formula 4]

[0048]

[0049] In the above formula (1), a plurality of Rs are identical divalent hydrocarbon groups having carbon atoms of 1 to 5. A part of the hydrogen atoms in the above hydrocarbon groups may be substituted with halogen atoms.

[0050] Examples of the divalent hydrocarbon group having 1 to 5 carbon atoms represented by R include divalent chain hydrocarbon groups having 1 to 5 carbon atoms and divalent alicyclic hydrocarbon groups having 3 to 5 carbon atoms. The chain hydrocarbon group may be linear or branched.

[0051] Examples of the divalent chain hydrocarbon group include a divalent chain saturated hydrocarbon group and a divalent chain unsaturated hydrocarbon group.

[0052] Examples of the above-mentioned divalent chain saturated hydrocarbon groups include methylenediyl (-CH2-), ethylenediyl (-C2H4-), propylenediyl (-C3H6-), butanediyl (-C4H8-), dimethylethylenediyl (-C4H8-), dimethylmethylenediyl (-C3H6-), and methylethylenediyl (-C3H6-).

[0053] Examples of the above-mentioned divalent chain unsaturated hydrocarbon groups include: vinyldiyl (-C2H2-), propylenediyl (-C3H4-), butenediyl (-C4H6-), methylenediyl (-C2H4-), methyleneethylenediyl (-C3H4-), methylenepropylenediyl (-C4H6-), vinylethylenediyl (-C4H6-), ethynediyl (-C2H2-), propynediyl (-C3H2-), butynediyl (-C4H4-), vinylethynyl (-C4H2-), ethynylpropylenediyl (-C5H4-), pentadiynediyl (-C5H2-), and the like.

[0054] Examples of the divalent alicyclic hydrocarbon group include a divalent alicyclic saturated hydrocarbon group and a divalent alicyclic unsaturated hydrocarbon group.

[0055] Examples of the divalent alicyclic saturated hydrocarbon group include a cyclopropanediyl group (—C 3 H 4 —), a cyclobutanediyl group (—C 4 H 6 —), and a cyclopentanediyl group (—C 5 H 8 —).

[0056] Examples of the divalent alicyclic unsaturated hydrocarbon group include cyclopentenediyl (—C 5 H 6 —) and the like.

[0057] Examples of the halogen atom that may substitute for a part of the hydrogen atoms in the hydrocarbon group include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0058] As the functional group, bis(2-pyridylmethyl)amino is preferred. Since the chelate resin has the functional group represented by the formula (1), the removal effect of the nickel-chromium containing layer can be further improved.

[0059] As the base material of the above-mentioned chelate resin, for example, polystyrene, styrene-divinylbenzene copolymer, etc. can be used. By using such a chelate resin, the effect of reducing the copper ions in the used removal solution is excellent.

[0060] As the method that resin is contacted with the above-mentioned used removing solution, for example can adopt the method for using known resin tower, in resin tower, fill above-mentioned resin.Then, used removing solution is flowed into the resin tower, from used containing layer removing solution, remove cupric ion.

[0061] In addition, as an alternative method for contacting the resin with the above-mentioned used removal solution, it is also possible not to use a resin tower, but directly drop into the used removal solution and remove the resin by filtering after a predetermined time.

[0062] The amount of the chelate resin used is preferably 50 L or more and 200 L or less relative to 200 L of the used removal liquid.

[0063] It should be noted that the regenerated removal liquid obtained after this step can also be returned to the step of removing the nickel-chromium containing layer. In this case, the removal step, the recovery step, and the contact step can be repeated on the same substrate to circulate the regenerated removal liquid. Alternatively, the regenerated removal liquid can be used in the step of removing the nickel-chromium containing layer of another substrate that can be implemented later.

[0064] <Regeneration removal liquid>

[0065] The regeneration removal solution disclosed in the present invention is obtained by the regeneration method of the removal solution. Preferably, the regeneration removal solution contains a pyridine compound, and the concentration of the pyridine compound exceeds 0 ppm and is 5000 ppm or less. Since the concentration of the pyridine compound is within the above range, the removal effect of the nickel-chromium containing layer is good.

[0066] When the resin has the functional group represented by the above-mentioned formula (1), it is possible to produce a trace of pyridine compounds from the above-mentioned functional group in the regeneration removal solution. This pyridine compound is a compound obtained by the decomposition of the resin with the above-mentioned functional group. Preferably, the pyridine compound concentration in the regeneration removal solution is 0ppm or exceeds 0ppm and is below 5000ppm. Due to the presence of pyridine compounds in the regeneration removal solution, the removal of nickel and chromium is hindered. Therefore, by arranging the pyridine compound concentration within the above-mentioned scope, the hindering effect of the removal of nickel and chromium by the above-mentioned pyridine compound can be reduced.

[0067] In addition, it is preferred that the regeneration removal solution further contains chloride ions and copper ions, has a pH of 1 or less, and has a copper ion concentration of 1 ppm or more and 2000 ppm or less. By making the regeneration removal solution have a strong acidity of pH 1 or less, the removal effect of the nickel-chromium containing layer containing nickel and chromium can be further improved. In addition, by making the copper ion concentration of the regeneration removal solution within the above range, the removal effect of the nickel-chromium containing layer can be improved.

[0068] The regeneration removal liquid disclosed in the present invention can be used as a removal liquid for removing the nickel-chromium containing layer from a substrate having a nickel-chromium containing layer and a copper containing layer in a semi-additive method. The removal method includes, for example, the same method as the above-mentioned (process of removing the nickel-chromium containing layer). The above-mentioned regeneration removal liquid can be mixed with an unused removal liquid or a used removal liquid for use.

[0069] [Other embodiments]

[0070] The embodiments disclosed herein are illustrative in all aspects and are not restrictive. The scope of the present disclosure is not limited to the configuration of the above embodiments, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0071] Example

[0072] Hereinafter, the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited to these examples.

[0073] [No.1~No.10]

[0074] Next, removing solutions No. 1 to No. 10 were prepared and their removal performance for the nickel-chromium containing layer in the printed wiring board was evaluated.

[0075] First, a base film consisting of a polyimide film with an average thickness of 25 μm is prepared. It should be noted that in the present disclosure, "average thickness" refers to the average value of the thickness measured at any 5 points. On both sides of the base film, a conductive pattern comprising 500 parallel wiring portions is formed by a semi-additive method. Specifically, a nickel-chromium containing layer with an average thickness of 4 nm composed of nickel and chromium is first stacked. Then, a conductive layer with an average thickness of 0.2 μm composed of copper is stacked. Then, a photoresist film is stacked on substantially the entire surface of the above-mentioned conductive layer by thermal compression bonding of an acrylic dry film resist. Then, the above-mentioned photoresist film is selectively exposed by using a photomask, thereby forming a portion that dissolves in a developer and a portion that does not dissolve in a developer on the above-mentioned photoresist film. Then, by rinsing the above-mentioned dissolved portion with a developer, a resist pattern having openings corresponding to the formation areas of multiple wiring portions is stacked.

[0076] Next, the surface of the conductive layer on which the resist pattern was laminated was subjected to copper electroplating using a 25° C. copper sulfate plating bath containing 90 g / L of copper sulfate pentahydrate, thereby laminating a metal layer having an average thickness of 10 μm.

[0077] Next, after laminating the metal layer, the resist pattern is removed using a resist removing solution, and then the conductive layer in the region where the metal layer is not laminated is removed using a conductive layer removing solution.

[0078] Next, the exposed nickel-chromium containing layer was removed. It should be noted that the composition of the unused removal solution was: 15% hydrochloric acid, 10% sulfuric acid, 50 ppm copper ion concentration, and pH 1 or less. In order to remove the nickel-chromium containing layer, the substrate was immersed in the unused removal solution at a liquid temperature of 45°C. The treatment time for removing the nickel-chromium containing layer was set to 30 seconds.

[0079] Then, in order to make used removing solution contact with resin, in resin tower, fill the resin of 50L, make used removing solution pass through with 10L / minute.As resin, use 3 kinds of resins with two (2-pyridylmethyl) amino, iminodiacetic acid group and aminophosphoric acid group respectively.The pH of the regeneration removing solution that obtains is all made as below 1.

[0080] The concentration of copper ions in the regenerated removal solution was determined by quantitatively analyzing the concentration of copper ions in the sample solution using an inductively coupled plasma (ICP) emission spectrometer.

[0081] The concentration of pyridine compounds in the regeneration removal solution was quantified as follows: Using UV-1800 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation, the sample solution was diluted with water, the absorbance at 263 nm was measured, and the concentration of pyridine compounds in the regeneration removal solution was quantitatively converted based on a pre-prepared standard curve of bis(2-pyridylmethyl)amine.

[0082] By adjusting the copper ion concentration of the used removal solution and the number of times of passing through the resin tower, the copper ion concentration and the pyridine compound concentration of the regenerated removal solution are changed. The copper ion concentration and the pyridine compound concentration of the regenerated removal solution of gained are as shown in Table 1 (No.2~No.10). It should be noted that, as No., the unused product is used to contain 15% hydrochloric acid, 10% sulfuric acid, 50ppm copper ion concentration, pH and be below 1 unused removal solution.

[0083] Next, in the manufacturing process of the printed wiring board manufactured to obtain the regeneration removal solution No. 2 to No. 10 mentioned above, the process up to the step of removing the conductive layer was carried out to obtain a printed wiring board. The line width and spacing of the printed wiring board were 10 μm / 10 μm. For the obtained printed wiring board, only the removal solution of the composition shown in Table 1 was used to remove the nickel-chromium containing layer in the area where the metal layer was not laminated among the above-mentioned nickel-chromium containing layer. In the step of removing the nickel-chromium containing layer, the substrate was immersed in the regeneration removal solution at a liquid temperature of 45°C. The treatment time for removing the nickel-chromium containing layer was set to 30 seconds.

[0084] [evaluate]

[0085] (Wiring peeling rate)

[0086] The number of printed wiring boards in which the nickel-chromium containing layer was removed by using the removing solutions No. 1 to No. 10 was checked by visual inspection to determine the occurrence rate [%] of peeling in the wiring portion.

[0087] (Short circuit occurrence rate caused by Ni-Cr containing layer residue)

[0088] The number of short circuits on the printed wiring boards from which the nickel-chromium containing layer was removed using the removal solutions No. 1 to No. 10 was measured by electrical inspection to determine the incidence rate [%] of short circuits caused by the nickel-chromium containing layer residues.

[0089] Evaluation results of the occurrence rate of peeling of the wiring portion and the occurrence rate of short circuits due to the nickel-chromium containing layer residue are shown in Table 1. In addition, "<10" of the pyridine compound concentration means that it is less than the detection limit (10 ppm).

[0090] [Table 1]

[0091]

[0092] As shown in Table 1, when the nickel-chromium containing layer was removed by using a regeneration removal solution (No. 2 to No. 8) regenerated by a chelating resin having a bis (2-pyridylmethyl) amino group, the stripping rate of the wiring portion was low, and the results were good. In particular, in No. 2, No. 4 and No. 5, similar to the unused product of No. 1, no stripping of the wiring portion and no short circuit caused by the nickel-chromium containing layer residue were found. In No. 2, No. 4 and No. 5, the concentration of copper ions in the regeneration removal solution was 50 ppm or more and 2000 ppm or less, and the concentration of pyridine compounds was 5000 ppm or less.

[0093] On the other hand, when the regeneration removal liquid (No. 9 and No. 10) regenerated by the chelate resin having an iminodiacetic acid group or an aminophosphoric acid group was used, the occurrence rate of peeling of the wiring portion was high.

[0094] As described above, according to the regeneration method of the removing solution disclosed in the present invention, the concentration of copper ions in the regenerated removing solution can be maintained low, so that the removal effect of the nickel-chromium containing layer can be improved, and the dissolution of copper contained in the wiring portion in the process of removing the nickel-chromium containing layer can be suppressed. Therefore, it can be understood that: while the life of the removing solution can be extended, even in the case of manufacturing a fine printed wiring board, it is possible to obtain a printed wiring board in which the peeling of the wiring portion can be suppressed.

Claims

1. A method for regenerating a removal solution, comprising: When a printed wiring board is manufactured by a semi-additive process, a step of removing the nickel-chromium-containing layer from a substrate having a nickel-chromium-containing layer and a copper-containing layer using a removing solution, wherein the removing solution contains hydrochloric acid, has a pH of 1 or less, and has a hydrochloric acid concentration of 5 mass % or more and 20 mass % or less, a step of recovering the used removal liquid, and A step of contacting the removing solution recovered in the step of recovering the used removing solution with a chelating resin, The chelate resin has a functional group represented by the following formula (1): [Chemical formula 1] In the formula (1), a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbon atoms, and a part of the hydrogen atoms in the hydrocarbon group may be substituted with halogen atoms.

2. The method for regenerating a removing solution according to claim 1, wherein: The functional group is a bis(2-pyridylmethyl)amino group.

3. A regeneration removal liquid, which is a regeneration removal liquid for a semi-additive process obtained by the regeneration method according to claim 1 or claim 2, The regeneration removal solution contains a pyridine compound, The pyridine compound concentration is more than 0 ppm and is 5000 ppm or less.

4. The regeneration removal solution according to claim 3, Further containing chloride ions and copper ions, The pH is 1 or less, and the concentration of the copper ions is 1 ppm or more and 2000 ppm or less.

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