Photoresist stripper and method for using the same

Abstract

This invention discloses a photoresist stripping solution and its method of use. The photoresist stripping solution comprises a first stripping solution and a second stripping solution. The photoresist stripping solution does not contain an organic base. The first stripping solution comprises 30 g / L to 45 g / L of an inorganic base, 5 wt% to 15 wt% of a first azole compound, 2 wt% to 10 wt% of a surfactant, and water. The inorganic base includes potassium hydroxide and sodium hydroxide. The second stripping solution comprises 30 wt% to 80 wt% of an alcohol ether solvent, 5 wt% to 15 wt% of a second azole compound, and water.

Description

[Technical Field]

[0001] This invention relates to a photoresist stripping solution and its application method, and particularly to a photoresist stripping solution free of organic amines and its application method. [Previous Technology]

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

[0003] In the process of stripping the dry film, a stripping solution is usually used to remove the photoresist dry film covering the micro-circuit. Currently available stripping solutions with sodium hydroxide as the main component have the advantages of low cost and fast stripping speed, but they produce a large amount of film debris after stripping. For micro-circuit, there is a defect of incomplete stripping, which makes the circuit board unable to pass quality control.

[0004] Therefore, another type of stripping solution containing inorganic and organic bases has appeared on the market. The organic base is usually an amine compound, such as ethanolamine or ethylenediamine. A better stripping effect can be achieved with the coexistence of inorganic and organic bases. However, the presence of organic amines gives the stripping solution an irritating odor, so there is still room for improvement.

[0005] Therefore, how to eliminate the use of organic amines while maintaining a certain degree of peeling effect through the improvement of the composition has become one of the important issues that this project aims to solve. [Summary of the Invention]

[0006] The technical problem to be solved by the present invention is to provide a photoresist stripping liquid and its application method in view of the shortcomings of the prior art.

[0007] To solve the above-mentioned technical problems, one of the technical solutions adopted by the present invention is to provide a photoresist stripping solution. The photoresist stripping solution includes a first stripping solution and a second stripping solution. The photoresist stripping solution does not contain an organic base. The first stripping solution includes 30 g / L to 45 g / L of an inorganic base, 5 wt% to 15 wt% of a first azole compound, 2 wt% to 10 wt% of a surfactant, and water. The inorganic base includes potassium hydroxide and sodium hydroxide. The second stripping solution includes 30 wt% to 80 wt% of an alcohol ether solvent, 5 wt% to 15 wt% of a second azole compound, and water.

[0008] In some embodiments, the weight ratio of potassium hydroxide to sodium hydroxide is 2.5 to 6.

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

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

[0011] In some embodiments, the surfactant is selected from the group consisting of: sodium dodecyl sulfate, octaalkyltrimethylammonium hydroxide, alkyl dimethylphenylammonium hydroxide, alkyl sulfate salts, phosphate salts, sulfosuccinates, glutamic acid salts, lauryl betaine, cocoaminopropyl 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] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a method for using a photoresist stripping solution. The method for using the photoresist stripping solution includes the following steps: applying a first stripping solution to a circuit board; applying a second stripping solution to the circuit board; mixing the first stripping solution and the second stripping solution in a weight ratio of 1:1 to 2:3, and adding 1 to 2.5 times the amount of water to form a third stripping solution; and applying the third stripping solution to the circuit board. The first stripping solution does not contain an organic base and comprises 30 g / L to 45 g / L of an inorganic base, 5 to 15 wt% of a first azole compound, 2 to 10 wt% of a surfactant, and water. The second stripping solution does not contain an organic base and comprises 30 to 80 wt% of an alcohol ether solvent, 5 to 15 wt% of a second azole compound, and water.

[0014] In some embodiments, the first stripping liquid, the second stripping liquid and the third stripping liquid are applied to the circuit board by spraying.

[0015] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a photoresist stripping solution. The photoresist stripping solution does not contain organic bases, and comprises: 1.5 g / L to 26 g / L of inorganic base, 0.45 wt% to 3.6 wt% of azole compounds, 0.45 wt% to 3 wt% of surfactants, 80 wt% to 90 wt% of alcohol ether solvents, and water. The inorganic base includes potassium hydroxide and sodium hydroxide.

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

[0017] One of the beneficial effects of the present invention is that the photoresist stripping solution and its method of use provided by the present invention can still have a good stripping effect without adding organic base by means of the technical solution of "the first stripping solution containing an inorganic base, a first azole compound and a surfactant" and "the second stripping solution containing an alcohol ether solvent and a second azole compound".

[0018] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention.

Implementation Method

[0021] The following specific embodiments illustrate the implementation of the "photoresist stripping liquid and its application method" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. In addition, the accompanying drawings of this invention are only simple schematic illustrations and are not depictions based on actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention. In addition, the term "or" used herein should be interpreted as potentially including any combination of one or more of the associated listed items, depending on the actual situation.

[0022] This invention adjusts the formulation of the stripping solution and improves its application method, enabling the photoresist stripping solution to maintain good stripping performance even after eliminating organic alkali (amine compounds) components. Therefore, the photoresist stripping solution of this invention can replace existing stripping solutions with irritating odors and can be applied to micro-circuits with a thickness of 3 mil or more.

[0023] The photoresist stripping fluid of the present invention is a two-dose photoresist stripping fluid, including an individually packaged first peeling fluid and a second peeling fluid. The first peeling liquid as well as the second peeling liquid can be used independently or after mixing, which can have a good peeling effect on the photoresist currently on the market.

[0024] For example, the applicable types of photoresist may be but are not limited to: ADH photoresist (photoresist containing acrylic monomer), t-BOC photoresist (photoresist containing tertiary butoxy carbonyl group group), Acetal photoresist (photoresist containing PHS-type copolymer). The above types are for illustration purposes only and do not limit the applicable types of photoresist.

[0025] In the photoresist stripping fluid, the first stripping fluid is used to peel off the dry film (formed by photoresist). The second stripping fluid does not actually have a stripping effect, but can make the dry film surging, the surging dry film is more likely to react with the first stripping fluid and remove from the line substrate. That is to say, the second peeling fluid can assist in the removal of the dry film by the first peeling fluid.

[0026] [First Film Peeling Liquid]

[0027] The first peeling fluid is mainly an aqueous solution, and the first peeling fluid does not contain organic bases (amine-like compounds). The first peeling solution contained an inorganic base at a concentration of 30 g / L to 45 g / L, a first azole (azole) compound from 5 wt percent to 15 wt percent, a surfactant from 2 wt percent to 10 wt percent, and water. Except for inorganic bases, first azole compounds and surfactants, the other components were water.

[0028] The above-mentioned inorganic base includes potassium hydroxide and sodium hydroxide, and the weight content of potassium hydroxide in the first stripping fluid is higher than the weight content of sodium hydroxide in the first stripping fluid. In an exemplary embodiment, the weight ratio of potassium hydroxide relative to sodium hydroxide in the first stripping fluid is 2.5 to 6, e.g.

[0029] In addition, the concentration of inorganic alkali (i.e., potassium hydroxide and sodium hydroxide) in the first peeling liquid may be an arbitrary positive integer between 30 g / L and 45 g / L. Preferably, the concentration of the inorganic base in the first peeling solution may be 32 g / L, 34 g / L, 36 g / L, 38 g / L, 40 g / L, 42 g / L, or 44 g / L.

[0030] The preparation method demonstrated in this specification is to first prepare potassium hydroxide solution and sodium hydroxide solution separately, mix appropriate amounts of potassium hydroxide solution and sodium hydroxide solution, then add other components (first azole compound and surfactant), and finally add water to reach the final volume. The specific preparation steps will be described in the examples.

[0031] Inorganic alkali has the effect of hydrolyzing esters (saponification). Therefore, the inorganic alkali in the first stripping solution can break the main chain crosslinking of the photoresist, causing the dry film to peel off into multiple sheets, thereby achieving the effect of removing the dry film.

[0032] Compared to the film-dissolving mechanism using organic bases, the film-stripping mechanism using inorganic bases in this invention is more conducive to continuous processes. The stripped dry film is in sheet form, so it can be easily removed by filtration, reducing the problem of waste liquid treatment.

[0033] It is worth noting that when inorganic alkali is used as a stripping solution, carboxylic acid, also known as fatty acid soap, is produced during the saponification of photoresist, which is prone to foaming. Therefore, inorganic alkali is prone to excessive foaming during the photoresist stripping process. When bubbles adhere to the circuit board, they reduce the photoresist stripping effect and lead to a decrease in production efficiency and yield.

[0034] In order to avoid the problem of excessive foaming, the present invention utilizes the characteristic that the surfactant can easily dissociate and form ions in strong alkali to reduce the structural stability of the foam. Therefore, it can avoid the formation of persistent foam and thus avoid excessive foaming, which would negatively affect the stripping effect of low light resistance.

[0035] The inorganic alkali selected above is highly alkaline and added at a high concentration. Therefore, in order to avoid erosion of the copper circuit during the stripping process of the dry film, the present invention adds a first azole compound to achieve the effect of protecting the copper surface. Furthermore, the content of the first azole compound in the first stripping solution can be any positive integer between 5% and 15% by weight.

[0036] A azole is a compound containing a five-membered heterocycle, which has at least two heteroatoms on its skeleton, and at least one of the heteroatoms is a nitrogen atom.

[0037] Experimental testing revealed that azole compounds containing three or more nitrogen atoms are preferred, such as triazole or tetraazole. Specifically, the first azole compound can be benzotriazole (BTA), tolytriazole (TTA), or 5-phenyl-1H-tetrazole, but the invention is not limited to these. On the other hand, when the azole compound has a thiol group, its adhesion to copper atoms is better; therefore, thiazole compounds containing only one nitrogen atom and one sulfur atom can be selected. Thus, the first azole compound can also be mercaptobenzothiazole.

[0038] The addition of surfactants can improve the wettability of the first stripping solution, which is beneficial for the inorganic alkali to penetrate between the circuits, thereby improving the stripping ability and speed. The content of surfactants in the first stripping solution can be any positive integer between 2% and 10% by weight.

[0039] In addition, the addition of surfactants can help disperse the first azole compound in the first stripping solution. Generally speaking, azole compounds have low solubility in water, and the first stripping solution is an aqueous solution, so the presence of surfactants is necessary.

[0040] In some embodiments, the surfactant may be sodium dodecyl sulfate, octaalkyltrimethylammonium hydroxide, alkyl dimethylphenylammonium hydroxide, alkyl sulfate salt, phosphate salt, sulfosuccinate, glutamic acid salt, lauryl betaine, cocoaminopropyl betaine or polyoxyethylene lauryl ether potassium phosphate, but the present invention is not limited thereto.

[0041] [Second stripping solution]

[0042] The second stripping solution is primarily an organic solution and does not contain any organic bases (amine compounds). The second stripping solution comprises 30 to 80% by weight of an alcohol ether solvent, 5 to 15% by weight of a second azole compound, and water. Except for the alcohol ether solvent and the second azole compound, all other components are water.

[0043] Alcohol ether solvents can penetrate photoresist, causing the dry film to swell, thus aiding in the removal of the dry film. If the first stripping solution is present, the alcohol ether solvent can support the dry film, providing a pathway for the inorganic base to react with the dry film, thereby increasing the stripping rate.

[0044] 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, or diethylene glycol dimethyl ether.

[0045] Azole compounds are also added to the second stripping solution. These compounds protect the copper circuitry from corrosion by residual inorganic alkali. The applicable azole compounds are similar to those described above and will not be repeated here. The second azole compound can be benzotriazole, mercaptobenzothiazole, methylbenzotriazole, or 5-phenyltetraazole. It should be noted that the first azole compound may be the same as or different from the second azole compound.

[0046] [Instructions for use of photoresist stripping solution]

[0047] Please refer to Figure 1. The photoresist stripping solution of the present invention is a two-component photoresist stripping solution. In use, a first stripping solution is first applied to the circuit board to remove most of the dry film (step S1); then a second stripping solution is applied to make the dry film swell and reduce the adhesion between the dry film and the circuit board (step S2). Next, the first stripping solution and the second stripping solution are mixed in a specific ratio to prepare a third stripping solution (step S3), and the third stripping solution is applied to the circuit board (step S4) to remove the remaining dry film.

[0048] The first azole compound in the first stripping solution adheres to the exposed circuit areas, achieving a protective effect on the copper surface. The inorganic base breaks the cross-linking of the photoresist's main chain, causing the dry film to peel off into sheets, which are then stably dispersed in the first stripping solution by the surfactant. However, in areas with narrower circuit spacing, the first stripping solution is less likely to penetrate between them, so a second stripping solution is added. The second stripping solution swells the dry film, providing channels for liquid to penetrate into areas with narrower circuit spacing. Therefore, after adding the third stripping solution, the third stripping solution can penetrate between the narrow circuits, causing the remaining dry film to peel off without damaging the already formed circuit.

[0049] In the step of preparing the third stripping solution, weigh out the first stripping solution and the second stripping solution in a weight ratio of 1:1 to 2:3, mix them, and add water in a total weight ratio of 1 to 2.5 times that of the first stripping solution and the second stripping solution to obtain the third stripping solution.

[0050] It should be noted that the third stripping solution is prepared from the first stripping solution, the second stripping solution, and water. Therefore, azole compounds are also added when designing the composition of the second stripping solution. This avoids the situation where the concentration of azole compounds in the prepared third stripping solution is insufficient and fails to protect the copper surface.

[0051] Specifically, after the above-described preparation method, the third stripping solution comprises 1.5 g / L to 26 g / L of inorganic base, 0.45 wt% to 3.6 wt% of azole compound, 0.45 wt% to 3 wt% of surfactant, 80 wt% to 95 wt% of alcohol ether solvent, and water. Except for the inorganic base, azole compound, surfactant, and alcohol ether solvent, all other components are water.

[0052] Specifically, the concentration of inorganic alkali in the first stripping solution is 1.15 to 30 times that in the third stripping solution. In other embodiments, the concentration ratio of inorganic alkali in the first stripping solution to that in the third stripping solution can be a positive integer between 1.15 and 30.

[0053] Since the third stripping solution is mainly for the dry film that is difficult to remove between narrow lines, the amount of the second stripping solution added will be greater than the amount of the first stripping solution added, so as to swell the dry film and provide channels for the third stripping solution to react with the residual dry film.

[0054] Since most of the dry film has been removed, a large amount of water is added to prevent the exposed copper surface from being corroded, and the exposed copper surface is protected with a first azole compound and a second azole compound.

[0055] It is worth noting that the first stripping solution is an aqueous solution, while the second stripping solution contains more organic solvents. Therefore, there is a possibility that the first and second stripping solutions may separate into layers. Since the first stripping solution contains surfactants, even if the first and second stripping solutions are mixed, a uniformly mixed third stripping solution can still be obtained.

[0056] Please refer to Figure 2. The present invention can apply the stripping solution by spraying, but the present invention is not limited thereto. During the stripping process, the circuit board S can be placed on the conveyor belt B and pass under the supply end L1 of the first stripping solution, the supply end L2 of the second stripping solution, and the supply end L3 of the third stripping solution in sequence. According to the above steps S1, S2, and S4, photoresist stripping solution is sprayed on the circuit board S to achieve the effect of removing the dry film.

[0057] Compared to conventional wet bench equipment, applying the stripping solution by spraying avoids the problem of dry film re-adhesion after stripping or poor stripping effect due to aging of the stripping solution after use. Furthermore, using a spraying method can reduce the amount of stripping solution used, achieving the desired effect with the minimum amount required.

[0058] [Test Examples 1 to 6]

[0059] To verify the effectiveness of the photoresist stripping solution of the present invention, an ADH photoresist with an acrylic base as the main component was used to form a dry film with a thickness of 25 micrometers or 30 micrometers on a circuit board (the specific thickness is listed in Table 1). Next, the first stripping solution, the second stripping solution and the third stripping solution were prepared according to the parts by weight in Table 1. Unless otherwise specified in Table 1, all units are parts by weight.

[0060] In test examples 1 to 6, a potassium hydroxide solution with a concentration of 45% to 50% by weight and a sodium hydroxide solution with a concentration of 45% to 50% by weight were first prepared. Then, the amount of potassium hydroxide solution and sodium hydroxide solution to be weighed and mixed was calculated so that the final first stripping solution could reach the target inorganic alkali concentration.

[0061] After calculation, the first stripping solution contains 50% to 85% by weight of potassium hydroxide solution and 10% to 25% by weight of sodium hydroxide solution, but the present invention is not limited thereto.

[0062] In addition, the first azole compound used in Test Examples 1 to 6 is benzotriazole, the surfactant is a phosphate salt, the alcohol ether solvent is diethylene glycol butyl ether, and the second azole compound is benzotriazole.

[0063] After the first stripping solution, the second stripping solution, and the third stripping solution are all prepared, three beakers are filled with the first stripping solution, the second stripping solution, and the third stripping solution, respectively. Under the conditions of 70°C and 600 revolutions per minute, the circuit board is immersed in the first stripping solution, the second stripping solution, and the third stripping solution in sequence for 180 seconds each to complete the film stripping process.

[0064] In the stripping process, since most of the dry film is removed in the first stripping solution, the time required for the circuit board to remove 80% of the dry film in the first stripping solution is recorded as the stripping time to evaluate the stripping effect of the first stripping solution on the dry film.

[0065] After the film stripping process is completed, the stripping ability of the photoresist stripping solution is evaluated based on the amount of residual dry film. When the amount of residual dry film is less than 1%, it is indicated by "O", and when the amount of residual film is greater than 1% but less than 5%, it is indicated by "∆". In addition, the oxidation state of the copper surface is evaluated based on the condition of the copper surface. When the proportion of copper oxide surface to the total copper surface is less than 1%, it is indicated by "O", and when the proportion of copper oxide surface to the total copper surface is greater than 3%, it is indicated by "X".

[0066] Table 1 (parts by weight) Test case 1 2 3 4 5 6 First stripping fluid potassium hydroxide solution 50 50 70 60 55 65 Sodium hydroxide solution 10 15 20 15 20 15 First-class azole compounds 0 1 3 5 5 5 surfactants 0 5 5 10 10 3 water 40 29 2 10 10 12 Inorganic base concentration (g / L) 30 32.5 45 37.5 37.5 40 KOH / NaOH weight ratio (-) 5 3.3 3.5 4 2.75 4.3 Second stripping fluid alcohol ether solvents 50 60 80 80 70 75 Second azole compounds 5 3 5 1 4 3 water 45 37 15 19 26 twenty two Third stripping fluid First stripping fluid 15 15 15 15 15 15 Second stripping fluid 15 15 15 15 15 15 water 70 70 70 70 70 70 Inorganic base concentration (g / L) 4.5 4.9 6.8 5.6 5.6 6.0 Dry film thickness (micrometers) 25 25 30 30 30 30 Peeling time (seconds) to remove 80% of the dry film 130 100 95 98 110 115 Film peeling ability assessment ∆ O O O O O Copper surface oxidation status assessment X O O O O O

[0067] As can be seen from the results in Table 1, the photoresist stripping solution and its application method of the present invention can effectively remove the dry film on the circuit board and maintain the circuit board with good quality. According to the results of Test Examples 1 to 6, when the circuit board is immersed in the first stripping solution, 80% of the dry film can be removed within 180 seconds, which confirms that the photoresist stripping solution of the present invention has a good stripping effect.

[0068] The results of Test Example 1 show that the addition of the first azole compound has a significant impact on the protection of the copper surface. Without the addition of the first azole compound, the copper surface is easily corroded and oxidized in a strongly alkaline environment. In addition, the surfactant affects the stripping effect of the first stripping solution. When no surfactant is added, the first stripping solution cannot properly wet the circuit board, thus limiting the stripping effect.

[0069] In addition, when the content of inorganic alkali in the first stripping solution is high, the stripping can be completed in a shorter time. However, if the content of inorganic alkali is too high, it will excessively corrode the substrate.

[0070] [Test Examples 7 to 12]

[0071] The operation and result evaluation methods of Test Examples 7 to 12 are similar to those of Test Examples 1 to 6, except that the composition ratio of the first stripping solution, the second stripping solution and water in the third stripping solution is different. The specific components of the first stripping solution, the second stripping solution and the third stripping solution are listed in Table 2. Unless otherwise specified, all units in Table 2 are parts by weight.

[0072] Table 2 (parts by weight) Test case 7 8 9 10 11 12 First stripping fluid potassium hydroxide solution 50 50 70 60 55 65 Sodium hydroxide solution 10 15 20 15 20 15 First-class azole compounds 0 1 3 5 5 5 surfactants 0 5 5 10 10 3 water 40 29 2 10 10 12 Inorganic base concentration (g / L) 30 32.5 45 37.5 37.5 40 KOH / NaOH weight ratio (-) 5 3.3 3.5 4 2.75 4.3 Second stripping fluid alcohol ether solvents 50 60 80 80 70 75 Second azole compounds 5 3 5 1 4 3 water 45 37 15 19 26 twenty two Third stripping fluid First stripping fluid 20 20 20 20 20 20 Second stripping fluid 30 30 30 30 30 30 water 50 50 50 50 50 50 Inorganic base concentration (g / L) 4.5 4.9 6.8 5.6 5.6 6.0 Dry film thickness (micrometers) 25 25 30 30 30 30 Peeling time (seconds) to remove 80% of the dry film 125 85 77 80 93 102 Film peeling ability assessment ∆ O O O O O Copper surface oxidation status assessment X O O O O O

[0073] According to the results in Table 2, the composition of the third stripping solution can be adjusted appropriately. When the water content in the third stripping solution is low, the time required to complete the stripping is also shorter. In one exemplary embodiment, the weight ratio of water in the third stripping solution is 45 wt% to 75 wt%, and can be any positive integer between 45 wt% and 75 wt%.

[0074] [Beneficial Effects of the Embodiments]

[0075] One of the beneficial effects of the present invention is that the photoresist stripping solution and its method of use provided by the present invention can still have a good stripping effect without adding organic base by means of the technical solution of "the first stripping solution containing an inorganic base, a first azole compound and a surfactant" and "the second stripping solution containing an alcohol ether solvent and a second azole compound".

[0076] Furthermore, the first stripping solution of the present invention can be used to remove dry film over a larger area, and the second and third stripping solutions can be used to remove dry film between narrow-pitch lines. In this way, a good stripping effect can be achieved without the use of organic alkali, and it can replace the stripping solutions with irritating odors that use organic alkali currently on the market.

[0077] Furthermore, the photoresist stripping solution of the present invention is convenient to use for users. The photoresist stripping solution includes separately packaged first and second stripping solutions, which is convenient to use. Moreover, without adding other ingredients, the third stripping solution can be easily prepared by simply weighing and adding an appropriate amount of water.

[0078] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention. [Simplified Explanation of the Diagram]

[0019] Figure 1 is a flowchart of the steps of using the photoresist stripping liquid of the present invention.

[0020] Figure 2 is a schematic diagram of the stripping process for the circuit board.

Claims

1. A photoresist stripping solution, which does not contain an organic base, said photoresist stripping solution comprising: A first stripping solution comprising: 30 g / L to 45 g / L of an inorganic base, said inorganic base including potassium hydroxide and sodium hydroxide; 5 wt% to 15 wt% of a first azole compound; 2 wt% to 10 wt% of a surfactant; and water; and a second stripping solution comprising: 30 wt% to 80 wt% of an alcohol ether solvent; 5 wt% to 15 wt% of a second azole compound; and water.

2. The photoresist stripping solution as described in claim 1, wherein, The weight ratio of potassium hydroxide to sodium hydroxide is 2.5 to 6.

3. The photoresist stripping solution as described in claim 1, wherein, The first azole compound is selected from the group consisting of: benzotriazole, mercaptobenzothiazole, methylbenzotriazole and 5-phenyltetrazazole.

4. The photoresist stripping solution as described in claim 1, wherein, The second azole compound is selected from the group consisting of: benzotriazole, mercaptobenzothiazole, methylbenzotriazole and 5-phenyltetrazazole.

5. The photoresist stripping solution as described in claim 1, wherein, The surfactant is selected from the group consisting of: sodium dodecyl sulfate, octaalkyltrimethylammonium hydroxide, alkyl dimethylphenylammonium hydroxide, alkyl sulfate salts, phosphate salts, sulfosuccinates, glutamic acid salts, lauryl betaine, cocoaminopropyl betaine, and polyoxyethylene lauryl ether potassium phosphate.

6. The photoresist stripping solution as described in 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. A method of using a photoresist stripping solution, comprising: A first stripping solution is applied to a circuit board substrate; wherein the first stripping solution does not contain an organic base, and comprises 30 g / L to 45 g / L of an inorganic base, 5 wt% to 15 wt% of a first azole compound, 2 wt% to 10 wt% of a surfactant, and water; a second stripping solution is applied to the circuit board substrate; wherein the second stripping solution does not contain an organic base, and comprises 30 wt% to 80 wt% of an alcohol ether solvent, 5 wt% to 15 wt% of a second azole compound, and water; the first stripping solution and the second stripping solution are mixed in a weight ratio of 1:1 to 2:3, and 1 to 2.5 times the amount of water is added to form a third stripping solution; and the third stripping solution is applied to the circuit board substrate.

8. The method of use as described in claim 7, wherein, The first stripping solution, the second stripping solution, and the third stripping solution are applied to the circuit board by spraying.

9. A photoresist stripping solution, which does not contain an organic base, said photoresist stripping solution comprising: An inorganic base ranging from 1.5 g / L to 26 g / L, wherein the inorganic base includes potassium hydroxide and sodium hydroxide; 1 to 5 wt% of azole compounds; 1 to 10 wt% of surfactants; 30 to 80 wt% of alcohol ether solvents; and water.

10. The photoresist stripping solution as described in claim 9, wherein, The azole compounds include at least one of benzotriazole, mercaptobenzothiazole, methylbenzotriazole, and 5-phenyltetrazazole.

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