Flexible circuit board and method and system for removing inner layer adhesive residue therefrom

Abstract

The application discloses a flexible circuit board and a method and system for removing inner layer adhesive residue of the flexible circuit board. The method comprises the following steps: in a chemical cleaning line provided with a chemical pretreatment tank, an adhesive removing tank and a first water washing tank are arranged respectively; the flexible circuit board to be processed is subjected to adhesive removing treatment by using the adhesive removing tank, so that a first flexible circuit board is obtained; the first flexible circuit board is subjected to cleaning by using the first water washing tank, so that a second flexible circuit board is obtained; the second flexible circuit board is subjected to chemical pretreatment by using the chemical pretreatment tank, so that a target flexible circuit board is obtained. The adhesive removing tank and the water washing tank are integrated in the traditional chemical cleaning line, so that the problem that the traditional chemical cleaning line cannot remove the inner layer adhesive residue of the flexible circuit board is solved, the removal of the inner layer adhesive residue of the flexible circuit board is realized, the high incidence of short circuit and poor performance of the flexible circuit board caused by adhesive residue reverse sticking is effectively avoided, and the yield is improved. Meanwhile, the film removing process after the adhesive layer and the copper surface are separated back to back is saved, the production capacity pressure of the film removing line is released, and manpower is saved.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing technology, specifically to a method and system for removing adhesive residue from flexible circuit boards and their inner layers. Background Technology

[0002] As flexible printed circuit (FPC) applications become increasingly thinner and more functionally diverse, there are growing demands for even thinner FPCs, denser wiring, and thinner materials. To meet these requirements, the manufacturing process for FPCs is becoming increasingly complex, thus placing higher demands on the investment costs and production efficiency of FPC production equipment.

[0003] In the manufacturing process of flexible printed circuit boards (FPCBs), two rolls of FPCB material are usually bonded together using back-to-back double-sided adhesive tape before being processed and flowed in the original FPCB manufacturing process. This not only improves production efficiency and saves on equipment investment, but also solves the problem of easy wrinkling caused by the thinness of FPCBs and stabilizes the expansion and contraction of FPCBs during the manufacturing process.

[0004] Furthermore, in the manufacturing process of multilayer boards, the inner layers undergo multiple chemical pretreatment etching processes before the outer layers are processed, requiring further etching of the copper surface. This can lead to a risk of the copper thickness being too thin in the final product. To mitigate this issue, the copper surfaces of the inner layers of multilayer boards are typically produced back-to-back, reducing the amount of etching required during the manufacturing process and ensuring that the outer copper thickness meets customer requirements.

[0005] However, in the above process, when the back-to-back adhesive layer is peeled off from the copper surface, adhesive residue is easily generated. The residual adhesive will stick to the circuit area inside the board, resulting in a high incidence of short circuit defects after the DES process (development → etching → film removal process), a large number of defective products, and affecting the yield. Ordinary chemical pretreatment methods cannot remove the residual adhesive. Summary of the Invention

[0006] In view of this, embodiments of the present invention provide a method and system for removing adhesive residue from flexible circuit boards and their inner layers, in order to solve the problem that ordinary chemical pretreatment methods in the prior art cannot remove the adhesive residue from the inner layers of flexible circuit boards, resulting in the adhesive residue sticking back and causing frequent short circuits in flexible circuit boards.

[0007] This invention provides a method for removing carbon residue during the manufacturing process of flexible printed circuit boards, comprising:

[0008] In a chemical cleaning line equipped with a chemical pretreatment tank, a degumming tank and a first water washing tank are respectively set up.

[0009] Using the adhesive removal tank in the chemical cleaning line, the flexible circuit board to be processed is de-adhesive-removed to obtain a first flexible circuit board.

[0010] The first flexible circuit board is cleaned using the first water washing tank in the chemical cleaning line to obtain the second flexible circuit board.

[0011] The second flexible circuit board is chemically pretreated using the chemical pretreatment tank in the chemical cleaning line to obtain the target flexible circuit board.

[0012] Optionally, the chemical cleaning line equipped with a chemical pretreatment tank includes a degumming tank and a first water rinsing tank, comprising:

[0013] Between the feed end of the chemical cleaning line and the chemical pretreatment tank, the degumming tank and the first water washing tank are respectively added;

[0014] The inlet of the degumming tank is connected to the feed end, the outlet of the degumming tank is connected to the inlet of the first washing tank, the outlet of the first washing tank is connected to the inlet of the chemical pretreatment tank, and the outlet of the chemical pretreatment tank is connected to the discharge end of the chemical cleaning line.

[0015] Optionally, the adhesive removal tank is provided with adhesive removal solution, and the first washing tank is provided with pure water.

[0016] Optionally, the adhesive removal tank in the chemical cleaning line is used to remove adhesive from the flexible circuit board to obtain a first flexible circuit board, comprising:

[0017] According to the preset adhesive removal parameters, the adhesive removal solution in the adhesive removal tank is used to remove adhesive from the flexible circuit board to be processed, thereby obtaining the first flexible circuit board.

[0018] Optionally, the preset adhesive removal parameters include adhesive removal solution concentration, adhesive removal tank conductivity, adhesive removal tank temperature, adhesive removal tank water replenishment amount, adhesive removal tank spray pressure, and adhesive removal tank length.

[0019] Optionally, the step of cleaning the first flexible circuit board using the first water washing tank in the chemical cleaning line to obtain the second flexible circuit board includes:

[0020] According to the first washing parameters, the first flexible circuit board is cleaned using pure water in the first washing tank to obtain the second flexible circuit board.

[0021] Optionally, the first water washing parameters include water replenishment volume, water washing spray pressure, and water washing tank length.

[0022] Optionally, the chemical pretreatment tank includes a micro-etching tank, a second water washing tank, and a drying tank connected in sequence;

[0023] The step of using the chemical pretreatment tank in the chemical cleaning line to perform chemical pretreatment on the second flexible circuit board to obtain the target flexible circuit board includes:

[0024] According to the preset micro-etching parameters, the second flexible circuit board is micro-etched using the micro-etching groove;

[0025] According to the second water washing parameters, the second flexible circuit board after micro-etching is cleaned using the second water washing tank;

[0026] The second flexible circuit board is dried in the drying tank at a preset drying temperature to obtain the target flexible circuit board.

[0027] Optionally, after performing chemical pretreatment on the second flexible circuit board using the chemical pretreatment tank in the chemical cleaning line, the process further includes:

[0028] The second flexible circuit board after chemical pretreatment is processed using a process of development, etching, and film removal.

[0029] In addition, the present invention also provides a system for removing adhesive residue from the inner layer of flexible circuit boards, including a chemical cleaning line, wherein the chemical cleaning line includes an adhesive removal tank, a water washing tank and a chemical pretreatment tank connected in sequence.

[0030] The adhesive removal tank is used to remove adhesive from the flexible circuit board to be processed, so as to obtain the first flexible circuit board.

[0031] The first water washing tank is used to clean the first flexible circuit board to obtain the second flexible circuit board;

[0032] The chemical pretreatment tank is used to perform chemical pretreatment on the second flexible circuit board to obtain the target flexible circuit board.

[0033] In addition, the present invention also provides a flexible circuit board, which is manufactured using the aforementioned removal method.

[0034] The beneficial effects of this invention are as follows: Traditional chemical cleaning lines include chemical pretreatment tanks, which can perform conventional treatments such as micro-etching, cleaning, and drying on flexible circuit boards through chemical pretreatment methods, but cannot remove residual adhesive on the inner layer of the flexible circuit board. This invention adds a desmearing tank and a water washing tank to the traditional chemical cleaning line, achieving the removal of residual adhesive on the inner layer of the flexible circuit board through only the chemical cleaning process, and cleaning the remaining impurities after desmearing (i.e., the desmearing medium remaining on the first flexible circuit board). Based on the second flexible circuit board after desmearing and cleaning, chemical pretreatment is performed again. By integrating the desmearing tank and water washing tank into the traditional chemical cleaning line, the problem of traditional chemical cleaning lines being unable to remove residual adhesive on the inner layer of the flexible circuit board is solved, achieving the removal of residual adhesive on the inner layer of the flexible circuit board, effectively avoiding the high incidence of short circuit defects caused by residual adhesive back-adhesion, and improving the yield. At the same time, it can also save the film removal process after the back-to-back adhesive layer is peeled off from the copper surface, achieving the same effect as the film removal line through only the chemical cleaning line, relieving the production capacity pressure of the film removal line and saving manpower. Attached Figure Description

[0035] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0036] Figure 1 A flowchart of a method for removing adhesive residue from the inner layer of a flexible circuit board according to Embodiment 1 of the present invention is shown;

[0037] Figure 2 A model diagram of a modified chemical cleaning line according to Embodiment 1 of the present invention is shown;

[0038] Figure 3 A model diagram of another modified chemical cleaning line according to Embodiment 1 of the present invention is shown;

[0039] Figure 4 The flowchart illustrates the chemical pretreatment process for a second flexible circuit board using a chemical pretreatment tank in Embodiment 1 of the present invention.

[0040] Figure 5 The figure shows the comparison test results of the defect rate obtained after processing with chemical cleaning lines before and after modification in Embodiment 1 of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for removing adhesive residue from the inner layer of a flexible circuit board, such as... Figure 1 As shown, it includes the following steps:

[0044] S1, in a chemical cleaning line equipped with a chemical pretreatment tank, a degumming tank and a first water washing tank are respectively set up.

[0045] Specifically, the chemical cleaning line is equipped with an inlet end, a chemical pretreatment tank, and an outlet end. The inlet of the chemical pretreatment tank is connected to the inlet end, and the outlet of the chemical pretreatment tank is connected to the outlet end.

[0046] Preferably, S1 includes:

[0047] Between the feed end of the chemical cleaning line and the chemical pretreatment tank, the degumming tank and the first water washing tank are respectively added;

[0048] The inlet of the degumming tank is connected to the feed end, the outlet of the degumming tank is connected to the inlet of the first washing tank, the outlet of the first washing tank is connected to the inlet of the chemical pretreatment tank, and the outlet of the chemical pretreatment tank is connected to the discharge end of the chemical cleaning line.

[0049] By adding a desmearing tank and a first washing tank between the feed end of the chemical cleaning line and the chemical pretreatment tank, the flexible circuit board to be processed is directly fed into the desmearing tank from the inlet of the feed end of the chemical cleaning line for desmearing. Then, it is fed into the first washing tank through the outlet of the desmearing tank and the inlet of the first washing tank for cleaning. This makes it easy to remove the inner layer adhesive residue of the flexible circuit board and clean the remaining impurities after desmearing through only the chemical cleaning process, which solves the problem that traditional chemical cleaning lines cannot remove the inner layer adhesive residue of flexible circuit boards.

[0050] The model diagram of the chemical cleaning line in this embodiment, after adding the degumming tank and the first water washing tank, is as follows: Figure 2 As shown.

[0051] Specifically, the adhesive removal tank contains adhesive removal solution, and the first washing tank contains pure water.

[0052] In one specific embodiment, the adhesive remover is a sodium hydroxide solution.

[0053] Specifically, the outlet of the adhesive removal tank is equipped with absorbent sponge rollers and / or water-blocking rollers to effectively prevent the adhesive removal solution from being carried into the first rinsing tank; the inlet of the first rinsing tank is also equipped with absorbent sponge rollers and / or water-blocking rollers to effectively prevent the adhesive removal solution from being carried into the first rinsing tank; the outlet of the first rinsing tank is also equipped with absorbent sponge rollers and / or water-blocking rollers to prevent pure water in the first rinsing tank from being carried into the chemical pretreatment tank, affecting the function of the chemical pretreatment tank; through the above-mentioned arrangement of absorbent sponge rollers and / or water-blocking rollers, cross-contamination of the solutions can be prevented. The number of absorbent sponge rollers and / or water-blocking rollers installed at each inlet or outlet can be set and adjusted according to actual conditions.

[0054] like Figure 1 As shown, in step S2, the adhesive removal tank in the chemical cleaning line is used to remove adhesive from the flexible circuit board to be processed, thereby obtaining the first flexible circuit board.

[0055] Preferably, S2 includes:

[0056] According to the preset adhesive removal parameters, the adhesive removal solution in the adhesive removal tank is used to remove adhesive from the flexible circuit board to be processed, thereby obtaining the first flexible circuit board.

[0057] According to the preset adhesive removal parameters, the adhesive removal solution is used to remove the adhesive from the flexible circuit board to be treated. On the one hand, this can ensure a good adhesive removal effect on the inner layer of the flexible circuit board to be treated, effectively preventing the adhesive from sticking back and causing short circuits. On the other hand, it can facilitate the automation of the modified chemical cleaning line, which is conducive to improving the efficiency of the chemical cleaning process.

[0058] Preferably, the preset adhesive removal parameters include adhesive removal solution concentration, adhesive removal tank conductivity, adhesive removal tank temperature, adhesive removal tank water replenishment amount, and adhesive removal tank spray pressure.

[0059] Specifically, in this embodiment, the concentration of the adhesive remover (i.e., the concentration of the sodium hydroxide solution) is 4% to 6%, and / or the conductivity of the adhesive remover tank is 200 to 240 mS, and / or the temperature of the adhesive remover tank is 47 to 53°C, and / or the water replenishment rate of the adhesive remover tank is 40 to 100 L / H; the spray pressure of the adhesive remover tank is 1.2 to 1.8 Bar.

[0060] Preferably, the preset adhesive removal parameters also include the length of the adhesive removal tank.

[0061] In addition to adjusting the glue removal parameters to achieve the glue removal effect, the glue removal time can also be extended and the glue removal effect enhanced by adjusting the length of the glue removal tank.

[0062] Specifically, the length of the adhesive removal tank is 1.0 to 1.5 m.

[0063] In this embodiment, the length of the adhesive removal tank is 1.2m.

[0064] In addition, in this embodiment S2, the degumming tank is regularly replaced with chemicals according to the frequency of tank opening, which can ensure that the entire chemical cleaning line maintains a good degumming effect.

[0065] like Figure 1 As shown, in step S3, the first flexible circuit board is cleaned using the first water washing tank in the chemical cleaning line to obtain the second flexible circuit board.

[0066] Preferably, S3 includes:

[0067] According to the first washing parameters, the first flexible circuit board is cleaned using pure water in the first washing tank to obtain the second flexible circuit board.

[0068] According to the first water washing parameters, the first flexible circuit board is cleaned with pure water in the first water washing tank. On the one hand, it can effectively remove the residual adhesive remover on the first flexible circuit board, avoiding the impact of alkaline adhesive remover neutralizing acidic chemicals on subsequent processes, which is convenient for subsequent chemical pretreatment and DES processes. On the other hand, it can facilitate the automation of the modified chemical cleaning line, which is beneficial to improving the efficiency of the chemical cleaning process.

[0069] Preferably, the first water washing parameters include water replenishment volume and water washing spray pressure.

[0070] Specifically, in this embodiment, the water replenishment rate for washing is 300–500 L / H, and / or the water spray pressure for washing is 1.2–1.8 kg / cm². 2 .

[0071] Preferably, the first washing parameter further includes the length of the washing tank.

[0072] In addition to adjusting the water supply and spray pressure to remove the adhesive remover, the length of the washing tank can also be adjusted to extend the washing time and remove the adhesive remover.

[0073] Preferably, the length of the washing tank is 1.2 to 1.8 times the length of the adhesive removal tank.

[0074] Specifically, when the length of the adhesive removal tank is [1, 1.3] m, the length of the washing tank is 1.5 to 1.8 times the length of the adhesive removal tank; when the length of the adhesive removal tank is (1.3, 1.5] m, the length of the washing tank is 1.2 to 1.5 times the length of the adhesive removal tank. This arrangement achieves both thorough cleaning of the adhesive removal solution and water conservation.

[0075] Specifically, in this embodiment, as mentioned above, the length of the adhesive removal tank is 1.2m, and the length of the water washing tank is 1.5 times the length of the adhesive removal tank, which is 1.8m.

[0076] In addition, in this embodiment S3, the first water washing tank is changed regularly according to the first water washing tank changing frequency, which can ensure that the entire chemical cleaning line maintains a good cleaning effect on the residual adhesive remover.

[0077] like Figure 1 As shown, in step S4, the second flexible circuit board is chemically pretreated using the chemical pretreatment tank in the chemical cleaning line to obtain the target flexible circuit board.

[0078] Preferably, such as Figure 3 As shown, the chemical pretreatment tank includes a micro-etching tank, a second water washing tank, and a drying tank connected in sequence.

[0079] like Figure 4 As shown, S4 includes:

[0080] S41: According to the preset micro-etching parameters, the second flexible circuit board is micro-etched using the micro-etching groove;

[0081] S42: Clean the second flexible circuit board after micro-etching treatment using the second water washing tank according to the second water washing parameters;

[0082] S43: The second flexible circuit board after cleaning is dried in the drying tank according to the preset drying temperature to obtain the target flexible circuit board.

[0083] The chemical pretreatment tank and its corresponding chemical pretreatment method described above can improve the quality of the second flexible circuit board and facilitate subsequent manufacturing processes of the flexible circuit board, such as the DES process. Among them, micro-etching treatment of the second flexible circuit board can form a micro-rough surface on the copper layer surface of the second flexible circuit board to increase the adhesion with the plating layer. Cleaning the second flexible circuit board after micro-etching treatment can remove the residual micro-etching solution from the second flexible circuit board after micro-etching treatment.

[0084] Specifically, the micro-etching tank contains micro-etching solution, and the second water washing tank contains pure water.

[0085] In one specific implementation, the micro-etching solution is a sulfuric acid solution.

[0086] Preferably, in S41, the preset micro-etching parameters include micro-etching tank temperature, micro-etching tank pressure, micro-etching rate, micro-etching sulfuric acid concentration, micro-etching H2O2 concentration, and micro-etching copper concentration.

[0087] Specifically, in this embodiment S41, the temperature of the micro-etching tank is 27-33°C, and / or the pressure of the micro-etching tank is 0.7-1.3 Bar, and / or the micro-etching rate is 0.2-0.5 μm, and / or the concentration of the micro-etching sulfuric acid is 10-50 g / L, and / or the concentration of the micro-etching H2O2 is 5-15 g / L, and / or the concentration of the micro-etching copper is less than 20 g / L.

[0088] Preferably, in S42, the second washing parameter may be partially the same as the first washing parameter, or the second washing parameter may be exactly the same as the first washing parameter. Of course, the second washing parameter may also be different from the first washing parameter, depending on the specific situation.

[0089] Specifically, in this embodiment, the second washing parameters include the water replenishment volume and the water spray pressure. The water replenishment volume and water spray pressure in the second washing tank are the same as those in the first washing tank. That is, in S42 of this embodiment, the water replenishment volume is 300-500 L / H, and / or the water spray pressure is 1.2-1.8 kg / cm². 2 .

[0090] Specifically, in this embodiment S43, the preset drying temperature is 45-75°C.

[0091] Similarly, in this embodiment S4, the second water washing tank is also changed periodically according to the second water washing tank changing frequency.

[0092] In this embodiment, the frequency of the second water washing tank can be the same as or different from the frequency of the first water washing tank, depending on the specific situation.

[0093] Preferably, after S4, the following is also included:

[0094] The second flexible circuit board after chemical pretreatment is processed using a process of development, etching, and film removal.

[0095] The above process ensures that the required circuit patterns are etched onto the target flexible circuit board, and removes the circuit patterns from areas where etching is not required, thus ensuring that the target flexible circuit board conforms to the actual design.

[0096] The specific operational processes of the above-mentioned developing, etching, and film removal processes adopt existing technologies, and the specific details will not be repeated here.

[0097] In one specific embodiment, the process parameters of each tank in the modified chemical cleaning line are shown in Table 1 below, and the process parameters of each tank in the original chemical cleaning line (i.e., the traditional chemical cleaning line) are shown in Table 2. Batches of flexible circuit boards were processed using the two chemical cleaning lines described above, and the defect rates of the resulting batches of target flexible circuit boards were compared and tested. The comparison test results are as follows: Figure 5 As shown.

[0098] Table 1. Process parameters of each tank in the modified chemical cleaning line.

[0099]

[0100]

[0101] Table 2 Process parameters of each tank in a traditional chemical cleaning line

[0102]

[0103]

[0104] exist Figure 5 In this context, SC represents the probability of a short circuit, NK represents the probability of a line defect, and BC represents the probability of an open circuit. Figure 5 The comparative test results shown demonstrate that the chemical cleaning line (i.e., the modified chemical cleaning line) integrated with the adhesive removal tank and the first water washing tank in this embodiment can effectively reduce the probability of short circuit failures, thereby effectively preventing the high incidence of short circuit failures in flexible circuit boards caused by residual adhesive back-adhesion and improving product yield.

[0105] Example 2

[0106] A system for removing adhesive residue from the inner layer of a flexible circuit board includes a chemical cleaning line, wherein the chemical cleaning line comprises an adhesive removal tank, a water washing tank and a chemical pretreatment tank connected in sequence.

[0107] The adhesive removal tank is used to remove adhesive from the flexible circuit board to be processed, so as to obtain the first flexible circuit board.

[0108] The first water washing tank is used to clean the first flexible circuit board to obtain the second flexible circuit board;

[0109] The chemical pretreatment tank is used to perform chemical pretreatment on the second flexible circuit board to obtain the target flexible circuit board.

[0110] This embodiment achieves the removal of adhesive residue from the inner layer of flexible circuit boards (PCBs) and the cleaning of residual impurities (i.e., the adhesive removal medium remaining on the first PCB) through a single chemical cleaning process by adding a desmearing tank and a water washing tank to a traditional chemical cleaning line. Based on the desmeared and cleaned second PCB, a chemical pretreatment is then performed. Integrating the desmearing tank and water washing tank into the traditional chemical cleaning line solves the problem that traditional chemical cleaning lines cannot remove adhesive residue from the inner layer of PCBs, effectively preventing short circuits caused by residual adhesive sticking and improving yield. At the same time, it saves the need for the film removal process after peeling off the back-to-back adhesive layer from the copper surface, achieving the same effect as the film removal line through only the chemical cleaning line, relieving the production capacity pressure of the film removal line and saving manpower.

[0111] The functions performed by each tank in the removal system described in this embodiment correspond one-to-one with the removal method steps described in Embodiment 1. The structure of the removal system is as follows: Figure 3 and Figure 4 As shown, therefore, for details not covered in this embodiment, please refer to Embodiment 1 and... Figures 1 to 5 The specific description is omitted here.

[0112] Example 3

[0113] A flexible circuit board is manufactured using the removal method described in Example 1.

[0114] The flexible circuit board manufactured in this embodiment has excellent removal effect on the inner layer adhesive residue, effectively avoiding the high incidence of short circuit defects caused by residual adhesive back-adhesion, and improving the yield rate.

[0115] Similarly, the flexible circuit board described in this embodiment is manufactured using the removal method described in Embodiment 1. Therefore, for any details not covered in this embodiment, please refer to Embodiment 1 and... Figures 1 to 5 The specific description is omitted here.

[0116] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for removing adhesive residue from the inner layer of a flexible circuit board, characterized in that, include: In a chemical cleaning line equipped with a chemical pretreatment tank, a degumming tank and a first washing tank are respectively added between the feed end of the chemical cleaning line and the chemical pretreatment tank; wherein, the inlet of the degumming tank is connected to the feed end, the outlet of the degumming tank is connected to the inlet of the first washing tank, the outlet of the first washing tank is connected to the inlet of the chemical pretreatment tank, and the outlet of the chemical pretreatment tank is connected to the discharge end of the chemical cleaning line; the outlet of the degumming tank and the inlet and outlet of the first washing tank are both equipped with absorbent sponge rollers and / or water-blocking rollers to prevent cross-contamination of chemicals; Using the adhesive removal tank in the chemical cleaning line, the flexible circuit board to be processed is de-adhesive-removed to obtain a first flexible circuit board. The first flexible circuit board is cleaned using the first water washing tank in the chemical cleaning line to obtain the second flexible circuit board. The second flexible circuit board is chemically pretreated using the chemical pretreatment tank in the chemical cleaning line to obtain the target flexible circuit board. The adhesive removal tank contains an adhesive removal solution. Using the adhesive removal tank in the chemical cleaning line, the flexible circuit board to be processed is subjected to adhesive removal treatment to obtain a first flexible circuit board, comprising: According to preset adhesive removal parameters, the adhesive removal solution in the adhesive removal tank is used to remove adhesive from the flexible circuit board to be processed, thereby obtaining the first flexible circuit board; the preset adhesive removal parameters include an adhesive removal solution concentration of 4%~6%, an adhesive removal tank conductivity of 200~240mS, an adhesive removal tank temperature of 47~53℃, an adhesive removal tank replenishment rate of 40~100L / H, and an adhesive removal tank spray pressure of 1.2~1.8Bar; The first washing tank contains pure water. The process of cleaning the first flexible circuit board using the first washing tank in the chemical cleaning line to obtain the second flexible circuit board includes: According to the first washing parameters, the first flexible circuit board is cleaned using pure water in the first washing tank to obtain the second flexible circuit board; the first washing parameters include a water replenishment rate of 300~500L / H and a water volume of 1.2~1.8kg / cm³. 2 Water washing spray pressure.

2. The method for removing adhesive residue from the inner layer of a flexible circuit board according to claim 1, characterized in that, The preset adhesive removal parameters also include the length of the adhesive removal tank.

3. The method for removing adhesive residue from the inner layer of a flexible circuit board according to claim 1, characterized in that, The first water washing parameter also includes the length of the water washing tank.

4. The method for removing adhesive residue from the inner layer of a flexible circuit board according to any one of claims 1 to 3, characterized in that, The chemical pretreatment tank includes a micro-etching tank, a second water washing tank, and a drying tank connected in sequence. The step of using the chemical pretreatment tank in the chemical cleaning line to perform chemical pretreatment on the second flexible circuit board to obtain the target flexible circuit board includes: According to the preset micro-etching parameters, the second flexible circuit board is micro-etched using the micro-etching groove; According to the second water washing parameters, the second flexible circuit board after micro-etching is cleaned using the second water washing tank; The second flexible circuit board is dried in the drying tank at a preset drying temperature to obtain the target flexible circuit board.

5. The method for removing adhesive residue from the inner layer of a flexible circuit board according to any one of claims 1 to 3, characterized in that, After performing chemical pretreatment on the second flexible circuit board using the chemical pretreatment tank in the chemical cleaning line, the process further includes: The second flexible circuit board after chemical pretreatment is processed using a process of development, etching, and film removal.

6. A system for removing adhesive residue from the inner layer of a flexible circuit board, comprising a chemical cleaning line, applied in the method for removing adhesive residue from the inner layer of a flexible circuit board as described in any one of claims 1 to 5; characterized in that, The chemical cleaning line includes a glue removal tank, a first water washing tank, and a chemical pretreatment tank connected in sequence; the outlet of the glue removal tank and the inlet and outlet of the first water washing tank are equipped with water-absorbing sponge rollers and / or water-blocking rollers to prevent cross-contamination of the chemicals; the glue removal tank contains glue removal chemicals, and the first water washing tank contains pure water. The adhesive removal tank is used to remove adhesive from the flexible circuit board to be treated using the adhesive removal solution according to preset adhesive removal parameters, to obtain a first flexible circuit board; the preset adhesive removal parameters include an adhesive removal solution concentration of 4%~6%, an adhesive removal tank conductivity of 200~240mS, an adhesive removal tank temperature of 47~53℃, an adhesive removal tank water replenishment rate of 40~100L / H, and an adhesive removal tank spray pressure of 1.2~1.8Bar; The first washing tank is used to clean the first flexible circuit board with pure water according to the first washing parameters to obtain the second flexible circuit board; the first washing parameters include a water replenishment rate of 300~500L / H and a water flow rate of 1.2~1.8kg / cm³. 2 Water washing spray pressure; The chemical pretreatment tank is used to perform chemical pretreatment on the second flexible circuit board to obtain the target flexible circuit board.

7. A flexible circuit board, characterized in that, It is made using the removal method described in any one of claims 1 to 5.

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