Low-surface tension aluminum etching solution and preparation method and application thereof

Abstract

The invention discloses an aluminum etching solution with low surface tension. The aluminum etching solution comprises phosphoric acid, nitric acid, acetic acid, deionized water and a functional additive, the functional additive is prepared by carrying out a copolymerization reaction on alkylene phosphonic acid, polyol diene ether and an olefin-containing biquinoline derivative, and then reacting part of phosphonic acid groups with part of sodium hydroxide or potassium hydroxide. The low-surface-tension aluminum etching liquid disclosed by the invention has relatively low surface tension and can better wet the aluminum surface, so that the etching process is accelerated, the etching uniformity and precision are improved, the lateral etching phenomenon is reduced, and the etched pattern edge is clearer and the line is finer. The invention further discloses a preparation method and application of the low-surface tension aluminum etching liquid, and the method is simple and easy to implement and low in cost and has wide industrial application prospects. According to the etching solution and the preparation method thereof, the production quality and efficiency of the printed circuit board can be remarkably improved, and the requirement of the electronic manufacturing industry for a high-precision etching process is met.

Description

Technical Field

[0001] The invention relates to the technical field of etching liquid, and in particular to a low surface tension aluminum etching liquid and a preparation method and application thereof. Background Art

[0002] In the modern electronics manufacturing industry, aluminum is widely used as a conductive layer material for printed circuit boards (PCBs) due to its excellent conductivity and lightweight properties. In order to form fine circuit patterns during PCB manufacturing, the aluminum layer needs to be etched. Traditional aluminum etching solutions are usually mixed with phosphoric acid, nitric acid, and acetic acid. These etching solutions have some limitations during the etching process, such as slow etching speed, poor etching uniformity, severe side etching, and poor spreading due to high surface tension. These problems not only affect the etching quality, but may also lead to low yield and reduced production efficiency. In addition, traditional etching solutions may form a dense oxide film on the aluminum surface during the etching process, which hinders the further reaction of the etching solution with aluminum, thereby affecting the etching effect. Therefore, the industry has been seeking to improve the etching solution formula to increase the etching speed, uniformity, and selectivity, while reducing the side etching phenomenon and improving the spreading of the etching solution to meet the production needs of finer circuits. Summary of the invention

[0003] In view of the shortcomings of the above-mentioned technology, the present invention provides a low surface tension aluminum etching solution, which aims to solve the problems of slow etching speed, uneven etching, severe side etching, and poor spreading due to high surface tension of the etching solution in traditional etching solutions.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a low surface tension aluminum etching solution, the etching solution includes phosphoric acid, nitric acid, acetic acid, deionized water and functional additives; the functional additives are prepared by copolymerization of olefin phosphonic acid, polyol diene ether, and olefin-containing biquinoline derivatives, and then partial reaction of phosphonic acid groups with sodium hydroxide or potassium hydroxide.

[0005] As a preferred technical solution, the mass proportions of phosphoric acid, nitric acid and acetic acid in the etching solution are 60-65%, 7-9% and 5-15% respectively, the added amount of functional additives is 0.5-1.5%, and the balance is deionized water.

[0006] As a preferred technical solution, the olefin phosphonic acid is at least one of vinyl phosphonic acid, allyl phosphonic acid, 1-methyl vinyl phosphonic acid, (1-amino-2-propenyl)phosphonic acid, and cis-propenylphosphonic acid.

[0007] As a preferred technical solution, the polyol diene ether is at least one of di(2-allyloxyethyl) ether, diethylene glycol divinyl ether and triethylene glycol divinyl ether.

[0008] As a preferred technical solution, the olefin-containing biquinoline derivative is obtained by esterification reaction of 2,2'-biquinoline-4,4'-dicarboxylic acid with olefin alcohol and trifluoro alcohol.

[0009] As a preferred technical solution, the olefin alcohol is at least one of propenol, butenol and 2-methylallyl alcohol.

[0010] As a preferred technical solution, the trifluoroalcohol is at least one of 1,1,1-trifluoro-2-methyl-2-propanol, 4,4,4-trifluoro-2-methyl-1-butanol, 2,2,2-trifluoroethanol, 3,3,3-trifluoropropanol, 5,5,5-trifluoropentane-1-ol, 2-trifluoromethoxyethanol, 1,1,1-trifluoro-2-propanol, and 4,4,4-trifluorobutanol.

[0011] As a preferred technical solution, the molar ratio of the olefin phosphonic acid, the polyol diene ether and the olefin-containing biquinoline derivative is 4-7:5-10:1-3.

[0012] As a preferred technical solution, the amount of sodium hydroxide or potassium hydroxide added is 0.1 to 0.3 of the acid value of the copolymerization product.

[0013] Another aspect of the present invention is to provide a method for preparing the above-mentioned low surface tension aluminum etching solution, the preparation method comprising the following steps: S1: adding olefin phosphonic acid, polyol diene ether and olefin-containing biquinoline derivative into a reactor containing a solvent, stirring and mixing them evenly, adding a catalytic amount of initiator, heating and performing copolymerization reaction to obtain a phosphonic acid / diene ether / biquinoline copolymer; S2: dissolving the phosphonic acid / diolefin ether / biquinoline copolymer obtained in step S1 in a suitable solvent, and after the acid value is determined, adding a suitable amount of sodium hydroxide or potassium hydroxide to react to obtain a functional additive; S3: stirring and mixing the functional additive obtained in step S2 with phosphoric acid, nitric acid, acetic acid and deionized water to obtain the low surface tension aluminum etching solution.

[0014] The third aspect of the present invention is to provide an application of the low surface tension aluminum etching solution as described above, wherein the etching solution is applied to the etching of a printed circuit board (PCB) by the following steps: immersing the printed circuit board in the etching solution, ultrasonically vibrating for 1 to 5 minutes to complete the etching operation, then washing with ultrapure water and anhydrous ethanol alternately at least twice, and finally purging with high-purity nitrogen to complete the drying treatment of the printed circuit board.

[0015] Compared with the prior art, the invention has the following beneficial effects: the low surface tension aluminum etching liquid of the invention, the compounded additive, realizes the synergistic effect of multiple functional groups through the copolymerization reaction of olefin phosphonic acid, polyol diene ether and olefin-containing biquinoline derivative. The organic phosphonic acid functional group contained in the etching liquid of the invention not only chelates with the aluminum surface, but also interacts with the aluminum material by utilizing its acidic characteristics, thereby promoting the rapid and uniform dissolution of aluminum. This synergistic effect not only enhances the etching ability of the etching liquid to aluminum, but also significantly improves the selectivity and uniformity of etching. At the same time, the additive of the invention not only reduces the occurrence of side etching phenomenon by introducing biquinoline derivatives, ensures that the pattern edge after etching is clear and the lines are fine, but also further effectively controls the corrosion rate by introducing trifluoro groups, making the etching process more stable and predictable. In addition, due to its low surface tension characteristics, the etching liquid of the invention spreads more smoothly on the surface of the aluminum substrate, reducing the quality problems caused by uneven surface tension during the etching process.

[0016] The main chain of the additive of the present invention also contains abundant ether functional groups, which further reduce the surface tension of the etching solution, improve the wettability and spreadability of the etching solution, make the etching process more uniform, and improve the etching accuracy. In general, the etching solution prepared by compounding the additive of the present invention with phosphoric acid, nitric acid, and acetic acid not only has high selectivity and controlled etching characteristics for aluminum during the etching process, but also avoids the phenomenon of over-etching and uneven etching, thereby significantly improving the production quality and efficiency of printed circuit boards (PCBs). DETAILED DESCRIPTION

[0017] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0018] Embodiment 1, the low surface tension aluminum etching solution of this embodiment, the etching solution comprises phosphoric acid, nitric acid, acetic acid, deionized water and functional additives; the mass proportions of phosphoric acid, nitric acid and acetic acid in the etching solution are 60%, 7% and 5% respectively, the addition amount of functional additives is 0.5%, and the balance is deionized water; wherein the functional additives are prepared by copolymerization of allylphosphonic acid, di(2-allyloxyethyl) ether and olefin-containing biquinoline derivatives, and then partial reaction of phosphonic acid groups with sodium hydroxide. The molar ratio of allylphosphonic acid, di(2-allyloxyethyl) ether and olefin-containing biquinoline derivatives is 4:5:1.

[0019] The olefin-containing biquinoline derivative is obtained by firstly carrying out an esterification reaction between 2,2'-biquinoline-4,4'-dicarboxylic acid and allyl alcohol in a molar ratio of 1:1 under the action of a sulfuric acid solution, then adding 1,1,1-trifluoro-2-methyl-2-propanol, and continuing the esterification reaction. The molar ratio of 1,1,1-trifluoro-2-methyl-2-propanol to 2,2'-biquinoline-4,4'-dicarboxylic acid is 1:1.

[0020] The preparation method of the low surface tension aluminum etching solution of this embodiment comprises the following steps: S1: adding 0.04 mol of allylphosphonic acid, 0.05 mol of di(2-allyloxyethyl) ether and 0.01 mol of olefin-containing biquinoline derivative into a reactor containing 250 mL of dimethyl sulfoxide solvent, stirring and mixing evenly, adding a catalytic amount of initiator benzoyl peroxide, heating and performing copolymerization reaction at an operating temperature of 80° C. to obtain a phosphonic acid / diolefin ether / biquinoline copolymer; S2: 8 g of the phosphonic acid / diolefin ether / biquinoline copolymer obtained in step S1 is dissolved in 100 mL of a solvent (composed of deionized water and propylene carbonate in a volume ratio of 1:1), and after the acid value is determined, sodium hydroxide having an acid value of 0.2 of the phosphonic acid / diolefin ether / biquinoline copolymer is added for reaction to obtain a functional additive; S3: 0.5 g of the functional additive obtained in step S2 is stirred and mixed with 60 g of phosphoric acid, 7 g of nitric acid, 5 g of acetic acid and 27.5 g of deionized water to obtain the low surface tension aluminum etching solution. The surface tension of the aluminum etching solution of this embodiment is measured by using a surface tension meter and a maximum bubble pressure method; the result shows that the surface tension value is 9.7 mN / m.

[0021] The etching solution prepared by the preparation method of this embodiment is applied to the etching of a printed circuit board (PCB) through the following steps: the printed circuit board is immersed in the etching solution at 30° C., ultrasonically vibrated for 5 minutes to complete the etching operation, then alternately cleaned with ultrapure water and anhydrous ethanol at least twice, and finally purged with high-purity nitrogen to complete the drying process of the semiconductor chip.

[0022] The test results show that: there is no residue on the surface of the printed circuit board after etching, the etching rate is 15.2 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the etching film uniformity test result is 1.16 angstroms. Among them, the film uniformity test is carried out by measuring the thickness change of the film layer on a 6-inch printed circuit board. The immersion experiment was carried out at 30°C for 3 minutes, and 49 test points were evenly selected on the surface of the printed circuit board for measurement using a film thickness meter. The etching uniformity was evaluated by calculating the difference between the maximum and minimum film thicknesses of these test points (TTV).

[0023] Embodiment 2, the low surface tension aluminum etching solution of this embodiment, the etching solution comprises phosphoric acid, nitric acid, acetic acid, deionized water and functional additives; the mass proportions of phosphoric acid, nitric acid and acetic acid in the etching solution are 62%, 8% and 10% respectively, the addition amount of functional additives is 1%, and the balance is deionized water; wherein the functional additives are obtained by copolymerization of vinylphosphonic acid, diethylene glycol divinyl ether and olefin-containing biquinoline derivatives, and then partial reaction of phosphonic acid groups with sodium hydroxide. The molar ratio of vinylphosphonic acid, diethylene glycol divinyl ether and olefin-containing biquinoline derivatives is 5:7:2.

[0024] The olefin-containing biquinoline derivative is obtained by firstly carrying out an esterification reaction between 2,2'-biquinoline-4,4'-dicarboxylic acid and butenol in a molar ratio of 1:1 under the action of a sulfuric acid solution, then adding 4,4,4-trifluoro-2-methyl-1-butanol, and continuing the esterification reaction. The molar ratio of 4,4,4-trifluoro-2-methyl-1-butanol to 2,2'-biquinoline-4,4'-dicarboxylic acid is 1:1.

[0025] The preparation method of the low surface tension aluminum etching solution of this embodiment comprises the following steps: S1: adding 0.05 mol of vinylphosphonic acid, 0.07 mol of diethylene glycol divinyl ether and 0.02 mol of olefin-containing biquinoline derivative into a reactor containing 250 mL of dimethyl sulfoxide solvent, stirring and mixing evenly, adding a catalytic amount of initiator benzoyl peroxide, heating and performing copolymerization reaction at an operating temperature of 80° C. to obtain a phosphonic acid / diolefin ether / biquinoline copolymer; S2: 8 g of the phosphonic acid / diolefin ether / biquinoline copolymer obtained in step S1 is dissolved in 100 mL of a solvent (composed of deionized water and propylene carbonate in a volume ratio of 1:1), and after the acid value is determined, sodium hydroxide having an acid value of 0.3 of the phosphonic acid / diolefin ether / biquinoline copolymer is added for reaction to obtain a functional additive; S3: 1.0 g of the functional additive obtained in step S2 is stirred and mixed with 62 g of phosphoric acid, 8 g of nitric acid, 10 g of acetic acid and 19 g of deionized water to obtain the low surface tension aluminum etching solution. The surface tension of the aluminum etching solution of this embodiment is measured by using a surface tension meter and a maximum bubble pressure method; the result shows that the surface tension value is 8.9 mN / m.

[0026] The etching solution prepared by the preparation method of this embodiment is applied to the etching of a printed circuit board (PCB) through the following steps: the printed circuit board is immersed in the etching solution, ultrasonically vibrated for 5 minutes to complete the etching operation, then alternately cleaned with ultrapure water and anhydrous ethanol at least twice, and finally purged with high-purity nitrogen to complete the drying process of the semiconductor chip.

[0027] The test results show that: there is no residue on the surface of the printed circuit board in this embodiment after etching, the etching rate is 15.8 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the etching film uniformity test result is 1.16 angstroms.

[0028] Embodiment 3, the low surface tension aluminum etching solution of this embodiment, the etching solution comprises phosphoric acid, nitric acid, acetic acid, deionized water and functional additives; the mass proportions of phosphoric acid, nitric acid and acetic acid in the etching solution are 65%, 9% and 12% respectively, the amount of functional additives added is 1.5%, and the balance is deionized water; wherein the functional additives are prepared by copolymerization of 1-methylvinylphosphonic acid, triethylene glycol divinyl ether and olefin-containing biquinoline derivatives, and then partial reaction of phosphonic acid groups with sodium hydroxide. The molar ratio of 1-methylvinylphosphonic acid, triethylene glycol divinyl ether and olefin-containing biquinoline derivatives is 7:10:3.

[0029] The olefin-containing biquinoline derivative is obtained by firstly subjecting 2,2'-biquinoline-4,4'-dicarboxylic acid and 2-methylallyl alcohol in a molar ratio of 1:1 to an esterification reaction under the action of a sulfuric acid solution, then adding 2,2,2-trifluoroethanol, and continuing the esterification reaction. The molar ratio of 2,2,2-trifluoroethanol to 2,2'-biquinoline-4,4'-dicarboxylic acid is 1:1.

[0030] The preparation method of the low surface tension aluminum etching solution of this embodiment comprises the following steps: S1: adding 0.07 mol 1-methyl vinylphosphonic acid, 0.1 mol triethylene glycol divinyl ether and 0.03 mol olefin-containing biquinoline derivative into a reactor containing 250 mL of dimethyl sulfoxide solvent, stirring and mixing evenly, adding a catalytic amount of initiator benzoyl peroxide, heating and performing copolymerization reaction at an operating temperature of 80° C. to obtain a phosphonic acid / diolefin ether / biquinoline copolymer; S2: 8 g of the phosphonic acid / diolefin ether / biquinoline copolymer obtained in step S1 is dissolved in 100 mL of a solvent (composed of deionized water and propylene carbonate in a volume ratio of 1:1), and after the acid value is determined, sodium hydroxide having an acid value of 0.1 of the phosphonic acid / diolefin ether / biquinoline copolymer is added for reaction to obtain a functional additive; S3: 1.5 g of the functional additive obtained in step S2 is stirred and mixed with 65 g of phosphoric acid, 9 g of nitric acid, 12 g of acetic acid and 12.5 g of deionized water to obtain the low surface tension aluminum etching solution. The surface tension of the aluminum etching solution of this embodiment is measured by using a surface tension meter and a maximum bubble pressure method; the result shows that the surface tension value is 9.2 mN / m.

[0031] The etching solution prepared by the preparation method of this embodiment is applied to the etching of a printed circuit board (PCB) through the following steps: the printed circuit board is immersed in the etching solution, ultrasonically vibrated for 5 minutes to complete the etching operation, then alternately cleaned with ultrapure water and anhydrous ethanol at least twice, and finally purged with high-purity nitrogen to complete the drying process of the semiconductor chip.

[0032] The test results show that: there is no residue on the surface of the printed circuit board in this embodiment after etching, the etching rate is 16.3 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the test result of etching film uniformity is 1.21 angstroms.

[0033] Embodiment 4, the preparation method of the low surface tension aluminum etching liquid of this embodiment, its raw material composition and preparation steps are basically the same as those of embodiment 1, except that, in the preparation method of this embodiment, the olefin phosphonic acid adopts (1-amino-2-propylene) phosphonic acid instead of allyl phosphonic acid, the polyol diene ether adopts triethylene glycol divinyl ether instead of di(2-allyloxyethyl) ether, and the trifluoro alcohol adopts 3,3,3-trifluoropropanol instead of 1,1,1-trifluoro-2-methyl-2-propanol. After testing, the surface tension value of the low surface tension aluminum etching liquid of this embodiment is 9.6mN / m.

[0034] The test results show that: there is no residue on the surface of the printed circuit board in this embodiment after etching, the etching rate is 15.5 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the etching film uniformity test result is 1.17 angstroms.

[0035] Embodiment 5, the preparation method of the low surface tension aluminum etching liquid of this embodiment, its raw material composition and preparation steps are basically the same as those of embodiment 1, except that, in the preparation method of this embodiment, the olefin phosphonic acid adopts cis-propylene phosphonic acid instead of allyl phosphonic acid, the polyol diolefin ether adopts diethylene glycol divinyl ether instead of di(2-allyloxyethyl) ether, the olefin alcohol adopts 2-methylallyl alcohol instead of propenol, and the trifluoro alcohol adopts 5,5,5-trifluoropentane-1-ol instead of 1,1,1-trifluoro-2-methyl-2-propanol. After testing, the surface tension value of the low surface tension aluminum etching liquid of this embodiment is 9.8mN / m.

[0036] The test results show that: there is no residue on the surface of the printed circuit board in this embodiment after etching, the etching rate is 15.8 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the etching film uniformity test result is 1.15 angstroms.

[0037] Embodiment 6, the preparation method of the low surface tension aluminum etching liquid of this embodiment, its raw material composition and preparation steps are basically the same as those of embodiment 1, except that, in the preparation method of this embodiment, the olefin phosphonic acid uses vinyl phosphonic acid instead of allyl phosphonic acid, the olefin alcohol uses 2-methylallyl alcohol instead of propenol, and the trifluoro alcohol uses 2-trifluoromethoxyethanol instead of 1,1,1-trifluoro-2-methyl-2-propanol. After testing, the surface tension value of the low surface tension aluminum etching liquid of this embodiment is 9.5mN / m.

[0038] The test results show that: there is no residue on the surface of the printed circuit board of this embodiment after etching, the etching rate is 15 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the test result of etching film uniformity is 1.18 angstroms.

[0039] Embodiment 7, the preparation method of the low surface tension aluminum etching liquid of this embodiment, its raw material composition and preparation steps are basically the same as those of embodiment 1, except that, in the preparation method of this embodiment, the olefin phosphonic acid uses 1-methylvinylphosphonic acid instead of allylphosphonic acid, the olefin alcohol uses butenol instead of propenol, and the trifluoro alcohol uses 1,1,1-trifluoro-2-propanol instead of 1,1,1-trifluoro-2-methyl-2-propanol. After testing, the surface tension value of the low surface tension aluminum etching liquid of this embodiment is 10.1mN / m.

[0040] The test results show that: there is no residue on the surface of the printed circuit board of this embodiment after etching, the etching rate is 15.3 angstroms per minute, there is basically no lateral invasion under the condition of etching angle of 40 to 80 degrees, and the etching film uniformity test result is 1.16 angstroms.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A low surface tension aluminum etching solution, characterized in that: The etching solution comprises phosphoric acid, nitric acid, acetic acid, deionized water and functional additives; the functional additives are prepared by copolymerization of olefin phosphonic acid, polyol diene ether and olefin-containing biquinoline derivatives, and then partial reaction of phosphonic acid groups with sodium hydroxide or potassium hydroxide.

2. The low surface tension aluminum etching solution according to claim 1, characterized in that: The mass proportions of phosphoric acid, nitric acid and acetic acid in the etching solution are 60-65%, 7-9% and 5-15% respectively, the added amount of functional additives is 0.5-1.5%, and the balance is deionized water.

3. The low surface tension aluminum etching solution as claimed in claim 1, characterized in that: The olefin phosphonic acid is at least one of vinyl phosphonic acid, allyl phosphonic acid, 1-methyl vinyl phosphonic acid, (1-amino-2-propenyl)phosphonic acid, and cis-propenylphosphonic acid.

4. The low surface tension aluminum etching solution as claimed in claim 1, characterized in that: The polyol diene ether is at least one of di(2-allyloxyethyl) ether, diethylene glycol divinyl ether and triethylene glycol divinyl ether.

5. The low surface tension aluminum etching solution as claimed in claim 1, characterized in that: The olefin-containing biquinoline derivative is obtained by esterification reaction of 2,2'-biquinoline-4,4'-dicarboxylic acid with olefin alcohol and trifluoro alcohol.

6. The low surface tension aluminum etching solution as claimed in claim 1, characterized in that: The olefin alcohol is at least one of propenol, butenol and 2-methylallyl alcohol.

7. The low surface tension aluminum etching solution according to claim 1, characterized in that: The trifluoro alcohol is at least one of 1,1,1-trifluoro-2-methyl-2-propanol, 4,4,4-trifluoro-2-methyl-1-butanol, 2,2,2-trifluoroethanol, 3,3,3-trifluoropropanol, 5,5,5-trifluoropentane-1-ol, 2-trifluoromethoxyethanol, 1,1,1-trifluoro-2-propanol, and 4,4,4-trifluorobutanol.

8. The low surface tension aluminum etching solution as claimed in claim 1, characterized in that: The molar ratio of the olefin phosphonic acid, the polyol diene ether and the olefin-containing biquinoline derivative is 4-7:5-10:1-3.

9. A method for preparing a low surface tension aluminum etching solution as claimed in any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1: adding olefin phosphonic acid, polyol diene ether and olefin-containing biquinoline derivative into a reactor containing a solvent, stirring and mixing them evenly, adding a catalytic amount of initiator, heating and performing copolymerization reaction to obtain a phosphonic acid / diene ether / biquinoline copolymer; S2: dissolving the phosphonic acid / diolefin ether / biquinoline copolymer obtained in step S1 in a suitable solvent, and after the acid value is determined, adding a suitable amount of sodium hydroxide or potassium hydroxide to react to obtain a functional additive; S3: stirring and mixing the functional additive obtained in step S2 with phosphoric acid, nitric acid, acetic acid and deionized water to obtain the low surface tension aluminum etching solution.

10. Use of the low surface tension aluminum etching solution according to any one of claims 1 to 8, characterized in that: The etching solution is applied to the etching of the printed circuit board through the following steps: immersing the printed circuit board in the etching solution, ultrasonically vibrating for 1 to 5 minutes to complete the etching operation, then washing with ultrapure water and anhydrous ethanol alternately at least twice, and finally purging with high-purity nitrogen to complete the drying treatment of the printed circuit board.