Method for stripping a PCB

Abstract

The application belongs to the technical field of PCB manufacturing, and discloses a PCB film removing method, which comprises the following steps: pretreating a PCB plate after copper plating; removing glue from the pretreated PCB plate by using alkaline medicine; washing the PCB plate after glue removal; pickling the PCB plate after washing; and finally treating the PCB plate after pickling. By removing glue from the PCB plate by using alkaline medicine and pickling, neutralization treatment is performed, and the plate surface and dry film residues in the hole are removed by multiple water washing and ultrahigh pressure water washing, so that the problem that dry film debris and foreign matter residues in the hole in the film removing process of the high thickness-diameter ratio PCB plate cannot be removed is solved.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, and in particular to a method for removing the film from a PCB. Background Technology

[0002] With the current development of AI servers, products with a standard thickness-to-diameter ratio of 30:1 or less can meet the copper plating thickness requirements using VCP (Vertical Continuous Plating). For products with thickness-to-diameter ratios exceeding this, VCP manufacturing is currently difficult, and the significant difference in copper thickness between the thick BGA (Ball Grand Assay) plating area and the large copper surface area leads to difficulties in etching.

[0003] To meet the manufacturing requirements of products with high aspect ratios, spot plating (selective spot plating) is now widely used. During spot plating, a dry film is used to cover the areas that do not need to be plated, exposing the holes for electroplating. After electroplating, the dry film needs to be stripped. Since the aspect ratio of electroplated products is generally greater than 30:1, the organic stripping solution currently used produces small film fragments after stripping. These fragments can enter the holes of the PCB board, resulting in dry film residue inside the holes of the PCB board. Summary of the Invention

[0004] The purpose of this invention is to provide a method for removing film from PCBs, so as to solve the technical problem that dry film residue in the holes of PCB boards is difficult to completely remove in the prior art.

[0005] To achieve this objective, the present invention adopts the following technical solution: A method for removing the film from a PCB includes the following steps: S1, Pre-treatment of the copper-plated PCB board; S2, use alkaline solution to remove adhesive from the pre-treated PCB board; S3, wash the PCB board with water after removing the adhesive; S4, acid pickling is performed on the PCB board after water washing; S5 is the final processing step for the acid-washed PCB board.

[0006] As a further technical solution, the step of removing adhesive from the pretreated PCB board using an alkaline solution includes: The circulation rate of a single water jet in the glue removal cylinder needs to be controlled at 90L / min.

[0007] As a further technical solution, after the step of removing the adhesive from the pretreated PCB board with alkaline solution, the following is included: The mixture after degumming with alkaline solution is filtered.

[0008] As a further technical solution, the step of washing the PCB board after adhesive removal includes: The mixture after removing adhesive with alkaline solution is recycled and washed with water, and then the PCB board is neutralized.

[0009] As a further technical solution, between removing adhesive and pickling the PCB board, the PCB board needs to undergo multiple water jet washing and pressure rinsing.

[0010] As a further technical solution, multiple water jet washes are performed before and after the pressure rinsing, wherein the pressure rinsing method uses ultra-high pressure water washing, and the pressure requirement for ultra-high pressure water washing needs to meet 80-120 kg / cm². 2 It operates by oscillation.

[0011] As a further technical solution, the pretreatment step for the copper-plated PCB board includes: The PCB board was ultrasonically immersed in the ultrasonic wave at a frequency of 28kHz.

[0012] As a further technical solution, the step of pre-processing the copper-plated PCB board also includes: The PCB board is subjected to the following steps in sequence: expansion, multiple rinsing with film stripping solution, rinsing with new solution, rinsing with wastewater, HFS water washing, and then ultrasonic immersion washing.

[0013] As a further technical solution, the step of pre-processing the copper-plated PCB board also includes: The PCB board is first washed with water jet after ultrasonic immersion.

[0014] As a further technical solution, the steps for final processing of the acid-washed PCB board include: The PCB board is subjected to anti-oxidation treatment, multiple water jet washing, and dry board treatment before being removed from the circuit.

[0015] The beneficial effects of this invention are as follows: This invention provides a method for removing the film from a PCB, comprising the following steps: pre-treating the copper-plated PCB; removing the adhesive from the pre-treated PCB using an alkaline solution; washing the de-adhesive-removed PCB with water; acid-washing the washed PCB; and finally treating the acid-washed PCB. By performing alkaline de-adhesive removal and acid washing on the PCB surface and inside the holes, and through multiple water rinsing and ultra-high pressure rinsing, the residual dry film on the PCB surface and inside the holes is removed more thoroughly. This solves the technical problem of dry film residue and foreign matter residue inside the holes of high aspect ratio PCBs in the prior art, achieving the technical effect of no dry film residue residue inside the holes of the PCB and clean holes free of foreign matter. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the PCB film removal method mentioned in the embodiments of the present invention. Detailed Implementation

[0018] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0019] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0020] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0021] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0022] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0023] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0024] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0025] In related technologies, electroplating has been widely used to meet the manufacturing requirements of products with high aspect ratios. During electroplating, a dry film is used to cover the non-plating areas, exposing only the holes to be plated. After electroplating, the dry film needs to be removed. Because the aspect ratio of such products generally exceeds 30:1, the dry film fragments generated by existing conventional organic removal processes are small in size and easily enter the PCB board holes, making them difficult to remove and causing problems with dry film and foreign matter residue inside the holes.

[0026] In view of this, such as Figure 1As shown, some embodiments of the present invention provide a method for removing the film from a PCB, comprising the following steps: pre-treating the copper-plated PCB; removing the adhesive from the pre-treated PCB using an alkaline solution; washing the de-adhesive-removed PCB with water; acid-washing the water-washed PCB; and finally treating the acid-washed PCB.

[0027] In the spot plating process, dry film is applied to areas that do not require electroplating, leaving the holes on the PCB exposed for electroplating. After electroplating is complete, the dry film on the PCB is removed. During the removal process, some dry film fragments enter the holes on the PCB. In the above embodiments, the copper-plated PCB board is first pretreated by using an organic stripping solution to remove the dry film adhering to the board surface. Then, an alkaline solution is used to dissolve and remove the residual dry film inside the holes of the PCB board. The alkaline solution can be potassium permanganate solution or an aqueous solution with added manganese oxide to form manganese hydroxide, thereby dissolving and removing the residual dry film inside the holes of the PCB board. At this time, a flow meter needs to be installed in the chemical tank where the PCB board is located to detect the flow rate of the alkaline solution in the chemical tank and control the circulation of the chemical solution to better remove the residual dry film inside the holes. Then, the PCB board after the adhesive removal treatment is washed with water to remove the alkaline solution, dissolved dry film residue and organic foreign matter remaining on the PCB board surface and inside the holes, so as to avoid the chemical solution residue corroding the copper surface and substrate.

[0028] The PCB board is then pickled using either sulfuric acid or hydrochloric acid. The pickling process can be carried out by gradually diluting the acid from concentrated to diluted solutions, adjusting the pH level. Pickling chemically cleans and removes oxides, residues, and contaminants, while simultaneously activating the copper surface. This provides a clean, highly active substrate for subsequent PCB processes, ultimately ensuring the electrical performance and reliability of the circuit board. The pickling solution can be applied using a water jet cleaning method. After pickling, the PCB board undergoes further processing and is thoroughly dried before proceeding to the next step.

[0029] Some embodiments of the present invention provide a method for removing film from a PCB, comprising the following steps: pre-treating a copper-plated PCB board; removing the residual dry film on the surface and inside the holes of the pre-treated PCB board using an alkaline solution; washing the PCB board after removal of the adhesive with water; acid-washing the PCB board after water washing; and finally treating the acid-washed PCB board. By performing alkaline removal of the residual dry film on the surface and inside the holes of the PCB board and acid washing, and by multiple water rinsing and ultra-high pressure water rinsing, the residual dry film on the surface and inside the holes is removed more thoroughly, solving the technical problem of dry film residue and foreign matter residue in the holes of high aspect ratio PCB boards in the prior art, and achieving the technical effect of no dry film residue residue in the holes of the PCB board and clean holes free of foreign matter.

[0030] In this embodiment, the step of removing adhesive from the pretreated PCB board using alkaline solution includes controlling the circulation rate of a single water jet in the adhesive removal cylinder to 90L / min, thereby ensuring the penetration ability of the alkaline solution in the holes of the PCB board and improving the dissolution effect of the alkaline solution on the residual dry film in the holes of the PCB board.

[0031] Preferably, after the step of removing adhesive from the pretreated PCB board with alkaline solution, the following steps are included: filtering the mixture after removing adhesive with alkaline solution.

[0032] In the above embodiments, when using alkaline solutions to dissolve and remove adhesive residue from the holes of a PCB board, the residual dry film in the holes reacts with the alkaline solutions to generate suspended matter or flocculent matter. By adding an external filtration system to circulate and filter the solutions, the content of suspended matter in the solutions can be effectively reduced, and the phenomenon of residue generated after the dry film reacts with the solutions and remains in the holes can be reduced, thereby improving the overall cleaning effect.

[0033] The filtration system can employ filters: filters are one of the most commonly used devices for filtering acid and alkali liquids. They remove solid particles and impurities from liquids by passing filter elements or plates of different mesh sizes. The selection of filters can be customized based on particle size, flow requirements, and process characteristics. Common filters include cartridge filters, membrane filters, and bag filters.

[0034] Activated carbon adsorption can also be used: Activated carbon is a commonly used adsorption material for organic matter, odors, and residual chemicals in acidic and alkaline liquids. Activated carbon adsorption equipment removes organic impurities and odors from liquids through the adsorption effect of activated carbon, thereby improving the purity of the liquid.

[0035] Preferably, the step of washing the PCB board after desmearing includes: recycling the mixture after desmearing with alkaline solution and then neutralizing the PCB board.

[0036] In the above embodiments, after the alkaline solution is used to remove adhesive, the filtered solution is still alkaline and can be recycled and reused. The solution is recycled, and then the PCB board is washed with clean water. The washed PCB board is then placed in a neutralizing solution for spraying treatment. The neutralizing solution reacts with the alkaline solution remaining on the PCB board surface and in the holes to neutralize the alkaline residue and eliminate the alkaline residue.

[0037] As a preferred method, between removing adhesive and pickling the PCB board, the residual dry film on the PCB board surface and inside the holes needs to be subjected to multiple water jet washing and pressure rinsing.

[0038] In the above embodiments, water jet washing can be performed by pressurizing the PCB board surface and the holes to rinse the residual dry film. Pressurized rinsing can be used to rinse the holes of the PCB board in a targeted manner, or it can rinse the entire PCB board, thereby removing the residual dry film from the PCB board surface and the holes.

[0039] As a preferred method, multiple water jet washes are performed before and after pressure rinsing. The pressure rinsing method uses ultra-high pressure water washing, and the pressure requirement for ultra-high pressure water washing needs to meet 80-120 kg / cm². 2 It operates by oscillation.

[0040] In the above embodiments, before pressure rinsing, water jet washing can be performed, followed by pressure rinsing and multiple water jet washings, and then acid pickling and water jet washing, thereby effectively removing residual dry film from the board surface and holes. The ultra-high pressure water washing pressure is set to 80-120 kg / cm². 2 This design avoids impact damage to the PCB board caused by excessive water pressure during ultra-high pressure water washing and ensures effective removal of residual dry film inside the holes on the PCB board. In addition, the swinging operation increases the coverage area of ​​the high-pressure water flow on the PCB board during the swinging process, ensuring that all holes on the PCB board are covered. This allows the high-pressure water flow to impact the PCB board surface and deep holes from multiple angles and in all directions, further improving the removal effect of dry film residue and foreign matter inside the holes of the PCB board.

[0041] Preferably, the pretreatment steps for the coated PCB board include: ultrasonic immersion of the PCB board with the ultrasonic frequency set to 28kHz.

[0042] In the above embodiments, ultrasonic rinsing can be performed by using an ultrasonic instrument to emit ultrasonic waves to the solution in which the PCB board is immersed, so that the solution can perform ultrasonic rinsing on the PCB board, thereby making the PCB board cleaner, with better cleaning effect and better dry film removal effect.

[0043] In the above embodiments, the pretreated dry film is in a softened state after the film is removed. The vibration generated by ultrasonic immersion can effectively peel off and wash out the dry film residue remaining in the pores to a certain extent. The ultrasonic frequency used here is 28KHZ, which has a longer wavelength and stronger penetration, and can enhance the impact on the pores, thereby more effectively removing the residual dry film in the pores.

[0044] As a preferred option, the pretreatment steps for the copper-plated PCB board also include: sequentially expanding the PCB board, rinsing it with multiple stripping solutions, rinsing it with fresh solutions, rinsing it with wastewater, washing it with HFS water, and then performing ultrasonic immersion washing.

[0045] In the above embodiments, the bulking can be performed using ultrasonic bulking with an ultrasonic frequency F ≥ 20 kHz, preferably between 20 and 40 kHz. The dry film is then bulked, and at least three film removal processes can be performed. The film removal can be carried out by repeatedly rinsing with an organic film removal solution with a mass concentration of 3-5% to separate the dry film from the PCB board. Then, a fresh film removal solution is used for rinsing, followed by a rough wash with wastewater, and then a high-flow-rate (HFS) water wash. A large flow of clean water / pure water is used to rinse the PCB board surface and the holes to quickly dilute the residual solution and effectively remove the dry film residue from the PCB board surface and the holes. Then, ultrasonic immersion washing is performed to enhance the cleaning of the PCB board surface and the holes and improve the cleaning efficiency.

[0046] Preferably, the pretreatment steps for the copper-plated PCB board also include: performing a first water jet wash after ultrasonic immersion of the PCB board.

[0047] In the above embodiments, water jet washing can effectively remove residual ions and impurities, making the PCB board cleaner and preventing micro-contamination from the previous stage from being carried into the next stage, thus avoiding affecting the subsequent alkaline adhesive removal operation.

[0048] As a preferred option, the final processing steps for the acid-washed PCB board include: sequentially performing anti-oxidation treatment, multiple water jet washing, and dry board treatment before unloading.

[0049] In the above embodiments, in the final processing of the PCB board, after pickling, the PCB board surface is subjected to anti-oxidation treatment. The antioxidant forms a protective film on the clean board surface after pickling. Then, two water jet washes can be performed. After the two water jet washes, the PCB board is dried. The drying process can be carried out by a combination of water-absorbing sponge and hot air drying. The PCB board is fully dried by supplying air and heating it. Then, the dried PCB board is taken out and proceeds to the next process.

[0050] The overall operation process for dry film treatment of PCB boards can be as follows: expansion, three rinses with film stripping solution, rinsing with new solution, rinsing with wastewater, HFS water washing, sonic rinsing, first water jet washing, alkaline chemical desmearing, recycling water washing, second and third water jet washing, neutralization, fourth and fifth water jet washing, pressure rinsing, sixth water jet washing, seventh acid pickling water jet washing, anti-oxidation treatment, eighth and ninth water jet washing, dry board treatment, and board unloading.

[0051] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for removing the film from a PCB, characterized in that, Includes the following steps: S1, Pre-treatment of the copper-plated PCB board; S2, use alkaline solution to remove adhesive from the pre-treated PCB board; S3, wash the PCB board with water after removing the adhesive; S4, acid pickling is performed on the PCB board after water washing; S5 is the final processing step for the acid-washed PCB board.

2. The PCB stripping method according to claim 1, characterized in that, The step of removing adhesive from the pretreated PCB board using an alkaline solution includes: The circulation rate of a single water jet in the glue removal cylinder needs to be controlled at 90L / min.

3. The PCB stripping method according to claim 1, characterized in that, The process includes, after the step of removing adhesive from the pretreated PCB board using an alkaline solution: The mixture after degumming with alkaline solution is filtered.

4. The PCB stripping method according to claim 1, characterized in that, The step of washing the PCB board after adhesive removal includes: The mixture after removing adhesive with alkaline solution is recycled and washed with water, and then the PCB board is neutralized.

5. The PCB stripping method according to claim 1, characterized in that, Between de-adhesive removal and acid pickling of the PCB board, the PCB board needs to undergo multiple water jet washing and pressure rinsing.

6. The PCB stripping method according to claim 5, characterized in that, The pressure rinsing process involves multiple water jet washes before and after the pressure rinsing. The pressure rinsing method employs ultra-high pressure water washing, and the pressure requirement for ultra-high pressure water washing is 80-120 kg / cm². 2 It operates by oscillation.

7. The PCB stripping method according to claim 1, characterized in that, The steps for pre-processing the copper-plated PCB board include: The PCB board was ultrasonically immersed in the ultrasonic wave at a frequency of 28kHz.

8. The PCB stripping method according to claim 6, characterized in that, The pretreatment steps for the copper-plated PCB board also include: The PCB board is subjected to the following steps in sequence: expansion, multiple rinsing with film stripping solution, rinsing with new solution, rinsing with wastewater, HFS water washing, and then ultrasonic immersion washing.

9. The PCB stripping method according to claim 6, characterized in that, The pretreatment steps for the copper-plated PCB board also include: The PCB board is first washed with water jet after ultrasonic immersion.

10. The PCB stripping method according to claim 1, characterized in that, The steps for the final processing of the acid-washed PCB board include: The PCB board is subjected to anti-oxidation treatment, multiple water jet washing, and dry board treatment before being removed from the circuit.

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