Photoresist and method of using the same

Abstract

The present invention provides a photoresist stripping solution and a method for using the same.SOLUTION: The photoresist stripping solution includes a first stripping solution and a second stripping solution. The photoresist stripping solution does not comprise an organic base, and the first stripping solution comprises an inorganic base, 3% to 15% by weight of a first azole compound, 2% to 10% by weight of a surfactant, and water. Inorganic bases include potassium hydroxide and sodium hydroxide. The second stripping solution comprises 30 wt% to 80 wt% of an alcohol ether solvent, 1 wt% to 15 wt% of a second azole compound, and water. The concentration of the inorganic base in the first stripping solution is 30g / L to 45g / L.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photoresist stripper and a method for using the same, and more particularly to a photoresist stripper that does not contain an organic amine and a method for using the same. [Background technology]

[0002] The manufacturing process of a circuit board includes steps such as forming a copper surface, applying and developing a photoresist to the copper surface, covering some of the copper surface with a dry film, etching the exposed copper surface, and stripping the dry film.

[0003] In the dry film stripping process, a stripping solution is typically used to remove the photoresist dry film covering the fine pitch. While existing stripping solutions, primarily composed of sodium hydroxide, offer the advantages of low cost and fast stripping speed, they also generate relatively large amounts of scrap after stripping. For fine pitch circuits, this can result in defects, such as the film not being stripped cleanly, resulting in circuit boards that fail quality control.

[0004] Therefore, other types of film stripping solutions containing inorganic and organic bases are also commercially available. The organic bases are usually amine compounds such as ethanolamine and ethylenediamine. The coexistence of inorganic and organic bases can provide better stripping effects. However, the presence of organic amines causes the stripping solution to produce a pungent odor, which leaves room for improvement.

[0005] Therefore, one of the important issues for this business operator is to eliminate the use of organic amines while maintaining a certain level of stripping effect by improving the composition. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a photoresist stripper and a method for using the same in response to the shortcomings of the prior art. [Means for solving the problem]

[0007] To solve the above technical problems, one technical solution adopted by the present invention provides a photoresist stripping solution comprising a first stripping solution and a second stripping solution. The photoresist stripping solution does not contain an organic base. The first stripping solution contains an inorganic base, 1% to 15% by weight of a first azole compound, 2% to 10% by weight of a surfactant, and water. The inorganic base contains potassium hydroxide and sodium hydroxide. The second stripping solution contains 30% to 80% by weight of an alcohol ether solvent, 1% to 15% by weight of a second azole compound, and water. The concentration of the inorganic base in the first stripping solution is 30 g / L to 45 g / L.

[0008] In one embodiment, the weight ratio of potassium hydroxide to sodium hydroxide is 2.5-6.

[0009] In some embodiments, the first azole compound is selected from the group consisting of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole.

[0010] In some embodiments, the second azole compound is selected from the group consisting of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole.

[0011] In certain embodiments, the surfactant is selected from the group consisting of sodium dodecyl sulfate, octadecyltrimethylammonium hydroxide, alkyl dimethylphenyl ammonium hydroxide, alkyl sulfate ester salts, phosphate ester salts, sulfosuccinate esters, glutamate, lauryl betaine, cocamidopropyl betaine, and polyoxyethylene lauryl ether potassium phosphate.

[0012] In some embodiments, the alcohol ether solvent is selected from the group consisting of diethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol propyl ether, dipropylene glycol propyl ether, propylene glycol n-butyl ether, diethylene glycol dibutyl ether, tripropylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, diethylene glycol hexyl ether, diethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

[0013] Another technical solution adopted by the present invention to solve the above technical problems is to provide a method for using a photoresist remover. The method for using the photoresist remover includes applying a first remover to a circuit board, applying a second remover to the circuit board, mixing the first remover and the second remover in a weight ratio of 1:1 to 2:3 (first remover:second remover) and further adding 1 to 2.5 times the amount of water to prepare a third remover, and applying the third remover to the circuit board. The first remover does not contain an organic base, but contains an inorganic base, 1 to 15 wt % of a first azole compound, 2 to 10 wt % of a surfactant, and water, and the concentration of the inorganic base in the first remover is 30 g / L to 45 g / L. The second stripping solution does not contain an organic base, and contains 30% to 80% by weight of an alcohol ether solvent, 1% to 15% by weight of a second azole compound, and water.

[0014] In one embodiment, the first remover, the second remover, and the third remover are applied to the circuit board by spraying.

[0015] To solve the above technical problems, the present invention provides a photoresist stripper solution. The photoresist stripper solution does not contain an organic base, but contains an inorganic base, 1% to 5% by weight of an azole compound, 1% to 10% by weight of a surfactant, 30% to 80% by weight of an alcohol ether solvent, and water. The inorganic base includes potassium hydroxide and sodium hydroxide. The concentration of the inorganic base in the photoresist stripper solution is 1.5 g / L to 26 g / L.

[0016] In some embodiments, the azole compound includes at least one of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole. [Effects of the Invention]

[0017] One of the advantageous effects of the present invention is that the photoresist remover and the method of using the same according to the present invention can achieve good stripping effects without containing an organic base, thanks to the technical features that "the first remover contains an inorganic base, a first azole compound, and a surfactant" and "the second remover contains an alcohol ether solvent and a second azole compound." [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a flowchart showing a method for using the photoresist stripper according to the present invention. [Figure 2] 1A and 1B are schematic diagrams showing a circuit board undergoing a peeling treatment process. DETAILED DESCRIPTION OF THE INVENTION

[0019] In order to better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the drawings, however, the drawings are provided for reference and explanation only and do not limit the scope of the present invention.

[0020] The following describes a "photoresist stripper solution and its use" through specific embodiments, and those skilled in the art can understand the advantages and effects of the present invention based on the disclosure herein. The present invention can be implemented or applied in other different specific embodiments, and various modifications and changes can be made to the details herein based on different perspectives and applications without departing from the concept of the present invention. It should be noted in advance that the accompanying drawings are for simple schematic illustrations and are not drawn to scale. The technical content of the present invention will be described in more detail based on the following embodiments, but the disclosed content does not limit the scope of protection of the present invention. Furthermore, the term "or" used in the present specification may include any one or more combinations of the relevant listed items depending on the actual situation.

[0021] In the present invention, by adjusting the composition of the stripper and improving the method of use of the stripper, it is possible to achieve good stripping effect even if the organic base (amine compound) is removed from the photoresist stripper. Therefore, the photoresist stripper of the present invention can be used for fine pitches of 3 mils or more, replacing existing stripper solutions with pungent odors.

[0022] The photoresist stripper according to the present invention is a two-component photoresist stripper containing a first stripper and a second stripper, each packaged separately. The first and second strippers may be used independently, or they may be mixed together and then used. This combination provides excellent stripping effects for all photoresists currently available on the market.

[0023] For example, applicable types of photoresists include ADH photoresist (photoresist containing an acrylic monomer), t-BOC photoresist (photoresist containing a tert-butoxycarbonyl group), and acetal photoresist (photoresist containing a PHS-based copolymer), but the present invention is not limited to these. The above types are merely examples and do not limit the types of applicable photoresists.

[0024] In photoresist strippers, the first stripper is used to strip the dry film (formed by the photoresist). The second stripper does not actually have a stripping effect, but it can swell the dry film, which can then react more easily with the first stripper and be removed from the circuit board. That is, the second stripper can help the first stripper strip the dry film.

[0025] [First stripping solution] The first stripping solution is an aqueous solution and does not contain an organic base (amine compound). The first stripping solution contains an inorganic base, 1% to 15% by weight of a first azole compound, 2% to 10% by weight of a surfactant, and water. The concentration of the inorganic base in the first stripping solution is 30 g / L to 45 g / L. The entire composition other than the inorganic base, the first azole compound, and the surfactant is water.

[0026] The inorganic base includes potassium hydroxide and sodium hydroxide, and the weight content of potassium hydroxide in the first stripping solution is greater than the weight content of sodium hydroxide in the first stripping solution. In an exemplary embodiment, the weight ratio of potassium hydroxide to sodium hydroxide in the first stripping solution is 2.5 to 6, for example, 3, 3.5, 4, 4.5, 5, or 5.5.

[0027] The concentration of the inorganic base (i.e., potassium hydroxide and sodium hydroxide) in the first stripping solution may be any real number between 30 g / L and 45 g / L, and preferably 32 g / L, 34 g / L, 36 g / L, 38 g / L, 40 g / L, 42 g / L, or 44 g / L.

[0028] In the preparation method exemplified in the present specification, a potassium hydroxide solution and a sodium hydroxide solution are first prepared, and then appropriate amounts of the potassium hydroxide solution and the sodium hydroxide solution are mixed together. After that, other components (a first azole compound and a surfactant) are further added, and finally, water is added to reach the final volume. The specific preparation steps will be described in the Examples.

[0029] The inorganic base has the effect of hydrolyzing (saponifying) esters, so the inorganic base in the first stripping solution can interrupt the cross-linking of the photoresist backbone, causing the dry film to peel off into multiple flakes, thereby achieving the desired dry film stripping effect.

[0030] Compared with the film dissolution mechanism using an organic base, the film peeling mechanism using an inorganic base of the present invention is more advantageous for continuous production processes: the peeled dry film is in the form of a sheet, which can be easily removed by filtration, thereby mitigating the problem of waste liquid disposal.

[0031] It is worth noting that, when an inorganic base is used as a stripping solution, a carboxylic acid, also known as fatty acid soap, is generated during the saponification process of the photoresist, which tends to cause foaming. Therefore, when the inorganic base strips the photoresist, problems such as a large amount of foaming tend to occur, and if bubbles adhere to the circuit board, the photoresist stripping effect is reduced, leading to a decrease in production efficiency and yield.

[0032] To avoid the problem of excessive foaming, the present invention reduces the structural stability of the foam by utilizing the property of the surfactant that it easily dissociates in strong alkali to form ions, thereby avoiding the formation of foam that lasts for a long period of time, and further avoiding the adverse effect on the photoresist stripping effect due to excessive foaming.

[0033] The selected inorganic base is highly alkaline and its concentration is relatively high. Therefore, to prevent corrosion of the copper circuit during the dry film stripping process, the present invention adds a first azole compound to achieve the effect of protecting the copper surface. The content of the first azole compound in the first stripping solution may be any real number between 3% and 15% by weight. Preferably, the content of the first azole compound in the first stripping solution is between 5% and 15% by weight.

[0034] Azoles are compounds that contain a five-membered heterocyclic ring, and the backbone of the five-membered heterocyclic ring contains at least two heteroatoms, and the at least two heteroatoms contain at least one nitrogen atom.

[0035] Experiments have shown that it is preferable to select an azole compound containing three or more nitrogen atoms. For example, triazole or tetrazole. Specifically, the first azole compound may be benzotriazole (BTA), methylbenzotriazole (TTA), or 5-phenyl-1H-tetrazole, but the present invention is not limited thereto. On the other hand, since azole compounds containing a mercapto group have excellent adhesion to copper atoms, a thiazole compound containing only one nitrogen atom and one sulfur atom may be selected. Therefore, the first azole compound may be mercaptobenzothiazole.

[0036] The addition of a surfactant can improve the wettability of the first stripping solution, which is advantageous for the inorganic base to penetrate between the circuits, thereby improving the stripping ability and speed. The content of the surfactant in the first stripping solution may be any real number between 2% by weight and 10% by weight.

[0037] The addition of a surfactant also contributes to the dispersion of the first azole compound in the first stripping solution. Generally, azole compounds have low solubility in water, and the first stripping solution is an aqueous solution, so the presence of a surfactant is essential.

[0038] In some embodiments, the surfactant may be sodium dodecyl sulfate, octadecyltrimethylammonium hydroxide, alkyldimethylphenylammonium hydroxide, alkyl sulfate ester salts, phosphate ester salts, sulfosuccinate esters, glutamate salts, lauryl betaine, cocamidopropyl betaine, or potassium polyoxyethylene lauryl ether phosphate, but the present invention is not limited thereto.

[0039] [Second stripping solution] The second stripping solution is mainly an organic solution and does not contain an organic base (amine compound). The second stripping solution contains 30% to 80% by weight of an alcohol ether solvent, 5% to 15% by weight of a second azole compound, and water. The rest of the composition, other than the alcohol ether solvent and the second azole compound, is all water.

[0040] The alcohol ether-based solvent can penetrate the photoresist to swell the dry film, thereby contributing to the removal of the dry film. In the presence of the first stripping solution, the alcohol ether-based solvent can swell the dry film to provide a pathway for the inorganic base to react with the dry film, thereby improving the stripping speed.

[0041] For example, the alcohol ether solvent may be diethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol propyl ether, dipropylene glycol propyl ether, propylene glycol n-butyl ether, diethylene glycol dibutyl ether, tripropylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, diethylene glycol hexyl ether, diethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

[0042] The second stripper solution also contains an azole compound, which protects the copper circuit and prevents corrosion by residual inorganic bases. Suitable azole compounds are similar to the azole compounds described above, so a redundant description will not be provided here. The second azole compound may be benzotriazole, mercaptobenzothiazole, methylbenzotriazole, or 5-phenyltetrazole. It should be noted that the first azole compound may be the same as or different from the second azole compound.

[0043] [How to use photoresist remover] As shown in Figure 1, the photoresist remover according to the present invention is a two-component photoresist remover. When using the photoresist remover, a first remover is first applied to a circuit board to remove most of the dry film (step S1). Then, a second remover is applied to expand the dry film and reduce adhesion between the dry film and the circuit board (step S2). Next, the first and second removers are mixed in a specific ratio to prepare a third remover (step S3). The third remover is then applied to the circuit board to remove any remaining dry film (step S4).

[0044] The first azole compound in the first stripper adheres to the exposed circuitry and protects the copper surface. The inorganic base blocks crosslinking in the photoresist backbone, stripping the dry film into a sheet, while the surfactant stably disperses it in the first stripper. However, the first stripper has difficulty penetrating into areas with narrow circuit pitches, so a second stripper is added. The second stripper expands the dry film, providing a path for the first stripper to penetrate into areas with narrow circuit pitches. Therefore, after adding the third stripper, the third stripper penetrates between the fine pitches, allowing the remaining dry film to be stripped without damaging the formed circuit.

[0045] In the step of preparing the third stripping solution, the first stripping solution and the second stripping solution are weighed and mixed in a weight ratio of 1:1 to 2:3, and water is added in an amount of 1 to 2.5 times the total weight of the weighed first stripping solution and second stripping solution, thereby obtaining the third stripping solution.

[0046] It is worth noting that the third stripper solution is prepared from the first stripper solution, the second stripper solution, and water, and therefore the azole compound is also added when designing the components of the second stripper solution, thereby avoiding a situation in which the concentration of the azole compound in the prepared third stripper solution is insufficient to protect the copper surface.

[0047] Specifically, according to the above-mentioned preparation method, the third stripping solution contains an inorganic base, 1% to 5% by weight of an azole compound, 1% to 10% by weight of a surfactant, 30% to 80% by weight of an alcohol ether solvent, and water. The entire composition other than the inorganic base, the azole compound, the surfactant, and the alcohol ether solvent is water. The concentration of the inorganic base in the photoresist stripping solution is 1.5 g / L to 26 g / L.

[0048] Specifically, the concentration of the inorganic base in the first stripping solution is 1.15 to 30 times the concentration of the inorganic base in the third stripping solution. In another embodiment, the ratio of the concentrations of the inorganic base in the first stripping solution and the third stripping solution (concentration of the inorganic base in the first stripping solution / concentration of the inorganic base in the third stripping solution) may be a positive real number between 1.15 and 30.

[0049] Since the third stripping liquid is primarily used for the dry film between fine pitches that is difficult to strip, the amount of the second stripping liquid added is greater than the amount of the first stripping liquid added to expand the dry film and provide a path for the third stripping liquid to react with the remaining dry film.

[0050] Since most of the dry film has already been peeled off, a large amount of water is further added to prevent the exposed copper surface from being corroded, and the exposed copper surface is protected by the first azole compound and the second azole compound.

[0051] It is worth noting that the first and second stripping solutions may actually separate because the first solution is an aqueous solution and the second solution contains a large amount of organic solvent. However, because the first solution contains a surfactant, mixing the first and second solutions still results in a uniformly mixed third stripping solution.

[0052] 2, in the present invention, the stripping liquid can be applied by spraying, but the present invention is not limited to this. When performing the stripping treatment process, the circuit board S is placed on a conveyor belt B, and the circuit board S passes under the liquid supply end L1 of the first stripping liquid, the liquid supply end L2 of the second stripping liquid, and the liquid supply end L3 of the third stripping liquid in this order, and the photoresist stripping liquid is sprayed onto the circuit board S based on the steps S1, S2, and S4, thereby achieving the effect of stripping the dry film.

[0053] Compared to conventional wet batch equipment, spraying the stripper solution can avoid problems such as stickiness of the dry film after stripping and deterioration of the stripping effect due to aging after use. In addition, the spraying method can reduce the amount of stripper used, achieving the desired effect with a minimum amount of stripper.

[0054] [Experimental Examples 1-6] To demonstrate the effectiveness of the photoresist remover according to the present invention, a dry film having a thickness of 25 μm or 30 μm (specific thicknesses are shown in Table 1) was formed on a circuit board using an ADH photoresist whose main component is an acrylic group. Next, a first remover, a second remover, and a third remover were prepared based on the parts by weight shown in Table 1, and all units not specifically shown in Table 1 are parts by weight.

[0055] In Experimental Examples 1 to 6, a potassium hydroxide solution with a concentration of 45% by weight to 50% by weight and a sodium hydroxide solution with a concentration of 45% by weight to 50% by weight were first prepared, and then the amounts of potassium hydroxide solution and sodium hydroxide solution that needed to be weighed and mixed were calculated so that the final first stripping solution would reach the target inorganic base concentration.

[0056] As a result of calculation, 50% to 85% by weight of potassium hydroxide solution and 10% to 25% by weight of sodium hydroxide solution are added to the first stripping solution, but the present invention is not limited to this.

[0057] In addition, the first azole compound used in Experimental Examples 1 to 6 was benzotriazole, the surfactant was a phosphate ester salt, the alcohol ether solvent was diethylene glycol butyl ether, and the second azole compound was benzotriazole.

[0058] After the first, second, and third stripping solutions were all prepared, they were placed in three beakers, respectively. The circuit board was immersed in the first, second, and third stripping solutions, in that order, for 180 seconds each, at a temperature of 70°C and a rotation speed of 600 rpm, thereby completing the stripping process.

[0059] In the stripping process, most of the dry film is removed by the first stripping solution, so the time it took for the first stripping solution to remove 80% of the dry film from the circuit board was recorded as the stripping time, and the stripping effect of the first stripping solution on the dry film was evaluated.

[0060] After the stripping process was completed, the stripping ability of the photoresist stripper was evaluated based on the amount of remaining dry film. If the amount of remaining dry film was less than 1%, it was marked with "O". If the amount of remaining dry film was between 1% and 5%, it was marked with "△". In addition, the oxidation state of the copper surface was evaluated based on the condition of the copper surface, and if the copper oxide surface accounted for less than 1% of the total copper surface, it was marked with "O". If the copper oxide surface accounted for more than 3% of the total copper surface, it was marked with "X".

[0061] [Table 1]

[0062] According to the results in Table 1, the photoresist remover and its method of use of the present invention can effectively remove the dry film on the circuit board while maintaining the good quality of the circuit board. According to the results of Experimental Examples 1 to 6, when the circuit board was immersed in the first remover, 80% of the dry film could be removed within 180 seconds, proving that the photoresist remover of the present invention has a good stripping effect.

[0063] As can be seen from the results of Experimental Example 1, the addition of the first azole compound significantly affected the protection of the copper surface. Without the addition of the first azole compound, the copper surface was easily corroded and oxidized in a strongly alkaline environment. Furthermore, the surfactant affected the stripping effect of the first stripping solution; without the addition of the surfactant, the first stripping solution was unable to sufficiently wet the circuit board, limiting the stripping effect.

[0064] Furthermore, if the content of the inorganic base in the first stripping solution is high, the film can be stripped in a relatively short time, but if the content of the inorganic base is too high, it may corrode the substrate excessively.

[0065] [Experimental Examples 7-12] The operating methods and evaluation methods for Experimental Examples 7 to 12 and Experimental Examples 1 to 6 were similar, with the difference being the composition ratio of the first stripper, second stripper, and water in the third stripper solution. Specific components of the first stripper, second stripper, and third stripper solutions are shown in Table 2. Units not specifically shown in Table 2 are parts by weight.

[0066] [Table 2]

[0067] As can be seen from the results in Table 2, the components of the third stripping solution can be appropriately adjusted. The lower the water content in the third stripping solution, the shorter the time it takes to strip the film. In one exemplary embodiment, the weight ratio of water in the third stripping solution is 45 wt% to 75 wt%, and may be any positive real number between 45 wt% and 75 wt%.

[0068] [Advantageous Effects of the Embodiments] One of the advantageous effects of the present invention is that the photoresist remover and the method of using the same according to the present invention can have a good stripping effect without adding an organic base, due to the technical features that "the first remover contains an inorganic base, a first azole compound, and a surfactant" and "the second remover contains an alcohol ether solvent and a second azole compound."

[0069] Furthermore, the first stripper solution of the present invention can strip dry films over a relatively wide range, while the second and third strippers can remove dry films between fine pitches. Thus, they can achieve good stripping effects without using an organic base and can replace currently available strippers that contain organic bases and have a pungent odor.

[0070] Furthermore, the photoresist remover of the present invention has the advantage of being convenient for users. The photoresist remover contains the first and second removers packaged independently, which has the advantage of being convenient for users. Furthermore, the third remover can be easily formulated by simply measuring and adding an appropriate amount of water, without the need to add other components.

[0071] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, any equivalent technical modifications made using the specification and drawings of the present invention are included in the scope of the claims of the present invention. [Explanation of symbols]

[0072] S...Circuit board B...Conveyor belt L1...First stripping liquid supply end L2: Second stripping solution supply end L3...third stripping solution supply end

Claims

1. A photoresist stripping solution containing a first stripping solution and a second stripping solution without containing an organic base, The first stripping solution comprises: an inorganic base including potassium hydroxide and sodium hydroxide; 1% by weight to 15% by weight of a first azole compound; 2% to 10% by weight of a surfactant; and water, The second stripping solution comprises: 30% by weight to 80% by weight of an alcohol ether solvent; 1% by weight to 15% by weight of a second azole compound; and water, A photoresist stripping solution, wherein the concentration of the inorganic base in the first stripping solution is 30 g / L to 45 g / L.

2. 2. The photoresist stripping solution according to claim 1, wherein the weight ratio of said potassium hydroxide to said sodium hydroxide is 2.5 to 6.

3. 2. The photoresist stripping solution according to claim 1, wherein the first azole compound is selected from the group consisting of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole.

4. 2. The photoresist stripping solution according to claim 1, wherein the second azole compound is selected from the group consisting of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole.

5. 2. The photoresist stripper according to claim 1, wherein the surfactant is selected from the group consisting of sodium dodecyl sulfate, octadecyltrimethylammonium hydroxide, alkyldimethylphenylammonium hydroxide, alkyl sulfate ester salts, phosphate ester salts, sulfosuccinate esters, glutamate salts, lauryl betaine, cocamidopropyl betaine, and potassium polyoxyethylene lauryl ether phosphate.

6. 2. The photoresist stripper solution according to claim 1, wherein the alcohol ether solvent is selected from the group consisting of diethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol propyl ether, dipropylene glycol propyl ether, propylene glycol n-butyl ether, diethylene glycol dibutyl ether, tripropylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, diethylene glycol hexyl ether, diethylene glycol diethyl ether, and diethylene glycol dimethyl ether.

7. Applying a first stripping solution to the circuit board; applying a second stripping solution to the circuit board; preparing a third stripping solution by mixing the first stripping solution and the second stripping solution in a weight ratio of 1:1 to 2:3 (the first stripping solution: the second stripping solution) and further adding 1 to 2.5 times the amount of water; applying the third remover to the circuit board; the first stripping solution does not contain an organic base but contains an inorganic base, 3% by weight to 15% by weight of a first azole compound, 2% by weight to 10% by weight of a surfactant, and water, and the concentration of the inorganic base in the first stripping solution is 30 g / L to 45 g / L; A method for using a photoresist stripping solution, wherein the second stripping solution does not contain an organic base and contains 30% by weight to 80% by weight of an alcohol ether solvent, 1% by weight to 15% by weight of a second azole compound, and water.

8. 8. The method for using the photoresist remover according to claim 7, wherein the first remover, the second remover, and the third remover are applied to the circuit board by spraying.

9. A photoresist stripping solution that does not contain an organic base, an inorganic base including potassium hydroxide and sodium hydroxide; 1% by weight to 5% by weight of an azole compound; 1% to 10% by weight of a surfactant; 30% by weight to 80% by weight of an alcohol ether solvent; water, The photoresist stripping solution has a concentration of the inorganic base in the photoresist stripping solution of 1.5 g / L to 26 g / L.

10. 10. The photoresist stripping solution according to claim 9, wherein the azole compound includes at least one of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazole.

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