A method for recycling and regenerating the stripping waste liquid of a PCB board

Abstract

The present invention relates to a method for recycling and reusing the stripping waste liquid of a PCB board, which belongs to the technical field of energy conservation and environmental protection. The technical key points thereof include the following steps: a. Collect the stripping waste liquid; b. Dissociation and regeneration: Separate the esterified ink dissolved in the solution so that the ink is separated and suspended in the solution; c. Separation and purification: Filter the stripping liquid after dissociation and regeneration; d. Component adjustment and addition: After the solution is purified, it is recycled to the stripping production line, and 4% sodium hydroxide solution is added according to the component concentration. By using the method of the present application, this method can not only greatly reduce the discharge of COD in the waste liquid, but also reduce the material cost in production, and reduce the treatment pressure of the enterprise on the COD in the waste liquid. This invention can bring clean production, energy conservation and emission reduction, environmental protection to the enterprise, and also increase the economic benefits of the enterprise.

Description

Technical Field

[0001] This invention patent relates to the field of energy conservation and environmental protection, and particularly to a method for recycling and regenerating the stripping waste liquid of PCB boards. Background Art

[0002] With the rapid development of the electronics industry, PCB enterprises are growing larger and generating more and more wastewater. In the PCB stripping process, stripping liquid is used to remove the ink layer on the surface, and the resulting waste liquid is called stripping waste liquid.

[0003] For stripping liquid, generally, it can be divided into two technical routes: inorganic base and organic base. The former includes solutions such as CN115094423A and CN115418643A, and the latter includes solutions such as CN114900974A.

[0004] For the former, the characteristics of the stripping waste liquid of PCB boards are as follows: in the stripping process, the resist ink on the PCB board undergoes an esterification reaction with the hydroxide in the stripping liquid, and the esterified ink dissolves into the stripping liquid. Therefore, the treatment of the waste liquid is quite difficult and the cost is very high.

[0005] The applicant found in the treatment of stripping waste liquid that:

[0006] Document 1: CN114798194A (Shenzhen Chongda Multilayer Circuit Board Co., Ltd.) proposed a method and equipment for solid-liquid separation and recycling of PCB stripping waste liquid. Based on the characteristic that the dry film particles in the PCB stripping waste liquid have a density greater than that of the alkaline solution, the dry film particles are thrown to the side wall of the cavity to deposit by the centrifugal force generated when the centrifugal equipment rotates at high speed, while the alkaline solution stays in the middle position of the cavity, thus realizing the separation of the dry film particles from the alkaline solution. However, this method only filters the separable film residues, and part of the ink that forms the solution cannot be separated.

[0007] Document 2: CN115367907A (Shenzhen Ruise Environmental Protection Technology Co., Ltd.) proposed a comprehensive treatment method for various waste liquids of PCB boards. It uses micro-etching waste liquid and iron-containing absorption waste liquid to oxidize the organic matter in the stripping waste liquid (Fenton reaction). It cannot achieve the recycling of the stripping waste liquid.

[0008] Document 3: CN104386874A (Hongban (Jiangxi) Co., Ltd.) proposed a high-concentration waste liquid treatment process for the circuit board industry. However, this process cannot achieve the recycling of the stripping waste liquid.

[0009] In view of this problem, the applicant has invented a method for recycling and regenerating stripping waste liquid according to the characteristics of the waste liquid. This method can not only greatly reduce the discharge of COD in the waste liquid, but also reduce the material cost in production and relieve the enterprise's pressure on COD treatment in the waste liquid. This invention can bring clean production, energy conservation and emission reduction, environmental protection to the enterprise, and also increase economic benefits for the enterprise. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for recycling and regenerating stripping waste liquid of PCB boards to solve the problems existing in the background technology.

[0011] A method for recycling and regenerating stripping waste liquid of PCB boards includes the following steps:

[0012] a. Collect the stripping waste liquid;

[0013] b. Dissociation and regeneration: Separate the esterified ink dissolved in the solution so that the ink is separated and suspended in the solution;

[0014] c. Separation and purification: Filter the stripping solution after dissociation and regeneration;

[0015] d. Component adjustment and addition: After the solution is purified, it is recycled to the stripping production line, and 4% sodium hydroxide solution is added according to the component concentration.

[0016] In a further design, step a includes: The stripping waste liquid discharged from the stripping process mainly contains esterified ink dissolved in the solution; It is collected separately by a special pipe and cannot be mixed with other waste water solutions.

[0017] In a further design, step b includes: Using a titanium plate coated with rare metals as the anode electrode and a stainless steel plate as the cathode, and electrolyzing in the range of current density of 100 - 300 A / m 2 range. The esterified ink dissolved in the solution dissociates under the action of direct current, and the ink is separated and suspended in the solution; The solution after dissociation and regeneration is stored in a container.

[0018] In a further design, step b includes: Adding a 0.2% cationic polyacrylamide solution for mixing and stirring when the ratio of stripping waste liquid to flocculant is 1 / 1000 - 3 / 1000; Under the action of cations, the esterified ink dissociates from the solution and the ink is separated from the solution, so that the ink is separated and suspended in the solution.

[0019] In a further design, step c includes: Filtering and separating the ink in the stripping solution through a pp cotton core filter with a pore size of 5 um to purify the solution. After purification, the stripping solution is returned to the stripping tank of the production line.

[0020] Adopting the above technical solution, compared with the prior art, the advantages are as follows:

[0021] First, the basic concept of this application is: for the esterification ink dissolved in the solution, dissociate it from the solution; thus, it can be separated and purified.

[0022] Second, the second inventive point of this application lies in: using a direct current method to dissociate the esterification ink dissolved in the solution, and the ink separates and suspends in the solution; thus, it can be processed.

[0023] Third, the third inventive point of this application lies in: adding a 0.2% cationic polyacrylamide solution for mixing and stirring when the ratio of the film stripping waste liquid to the flocculant is 1 / 1000 - 3 / 1000. Under the action of cations, the esterification ink dissociates from the solution and the ink is separated from the solution, making the ink separate and suspend in the solution. Specific Embodiments

[0024] Example 1:

[0025] A method for recycling and reusing the film stripping waste liquid of a PCB board includes the following steps:

[0026] a. Collect the film stripping waste liquid: The film stripping waste liquid discharged from the film stripping process mainly contains esterification ink dissolved in the solution; it is collected separately using a special pipe and cannot be mixed with other waste water solutions.

[0027] b. Dissociation and regeneration: Using a titanium plate coated with rare metals as the anode electrode and a stainless steel plate as the cathode, electrolyze within the range of a current density of 100 - 300 A / m 2 The dissolved esterification ink in the solution dissociates under the action of the direct current, and the ink separates and suspends in the solution; store the dissociated and regenerated solution in a container.

[0028] c. Separation and purification: Filter the dissociated and regenerated film stripping liquid, and filter and separate the ink in the film stripping solution through a pp cotton core filter with a pore size of 5 um to purify the solution. After purification, the film stripping liquid is returned to the film stripping tank on the production line.

[0029] d. Component adjustment and addition: After the solution is purified and reused in the film stripping production line, add components such as 4% sodium hydroxide solution according to the component concentration to make the film stripping liquid concentration parameter within the qualified range.

[0030] At a film stripping liquid temperature of 50 °C, the comparison of the film stripping time and film stripping quality of the recycled and reused film stripping liquid and the original film stripping liquid during on-line testing is shown in Table 1 below.

[0031] Table 1

[0032]

[0033] Example 2:

[0034] A method for recycling and regenerating the film stripping waste liquid of a PCB board, comprising the following steps:

[0035] a. Collect the film stripping waste liquid: The film stripping waste liquid discharged from the film stripping process mainly contains esterified ink dissolved in the solution; it is collected separately by a dedicated pipe and cannot be mixed with other waste water solutions.

[0036] b. Dissociation and regeneration: Add a 0.2% cationic polyacrylamide solution for mixing and stirring when the ratio of the film stripping waste liquid to the flocculant is 1 / 1000 - 3 / 1000. Under the action of cations, the esterified ink dissociates from the solution and the ink is separated from the solution, so that the ink is separated and suspended in the solution.

[0037] c. Separation and purification: Filter the film stripping liquid after dissociation and regeneration, and filter and separate the ink in the film stripping solution through a pp cotton core filter with a pore size of 5um to purify the solution. After purification, the film stripping liquid is returned to the film stripping tank of the production line.

[0038] d. Component adjustment and addition: After the solution is purified and reused in the film stripping production line, components such as 4% sodium hydroxide solution are added according to the component concentration to make the concentration parameters of the film stripping liquid within the qualified range.

[0039] For the method of Example 2, at a film stripping liquid temperature of 50°C, the comparison of the film stripping time and film stripping quality of the recycled and reused film stripping liquid and the original film stripping liquid during on-line testing is shown in Table 2 below.

[0040] Through the test comparison, the film stripping time and film stripping quality of the film stripping waste liquid after regeneration and reuse are the same as the performance of the original film stripping liquid, and the regenerated film stripping liquid can meet the production requirements of the film stripping production line.

[0041] Table 2

[0042]

[0043]

[0044] The preferred embodiments of this aspect have been described in detail above, but it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention. These equivalent forms also fall within the protection scope of the appended claims of this application.

Claims

1. A method for recycling and regenerating the stripping waste liquid of a PCB board, characterized in that, It includes the following steps: a. Collect the stripping waste liquid: The stripping waste liquid discharged in the stripping process mainly contains esterified ink dissolved in the solution; It is collected separately by a dedicated pipe and cannot be mixed with other wastewater solutions; b. Dissociate and regenerate: Separate the esterified ink dissolved in the solution so that the ink is separated and suspended in the solution; It includes using a titanium plate coated with a rare metal as the electrode anode and a stainless steel plate as the cathode, and electrolyzing within the range of a current density of 100 - 300 A / m 2 so that the esterified ink dissolved in the solution dissociates under the action of a direct current, and the ink separates and suspends in the solution; Store the dissociated and regenerated solution in a container; c. Separate and purify: Filter the dissociated and regenerated stripping solution; It includes filtering and separating the ink in the stripping solution through a pp cotton core filter with a pore size of 5μm to purify the solution, and the purified stripping solution is returned to the stripping tank of the production line; d. Component adjustment and addition: After the solution is purified and reused in the stripping production line, add 4% sodium hydroxide solution according to the component concentration.

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