A PCB plating method and apparatus

Abstract

The application relates to a PCB electroplating method and device. The main groove and at least one auxiliary groove are cyclically communicated in the electroplating groove to improve the electroplating solution circulation amount, effectively enhance the solution flow and ion transmission capacity in the high-depth-width-ratio hole, solve the problem of uneven plating in the hole caused by the insufficient anode conductive area, improve the electroplating solution circulation amount and the plating uniformity in the high-depth-width-ratio hole, and improve the electroplating efficiency and product reliability.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, specifically to a PCB electroplating method and apparatus. Background Technology

[0002] As the printed circuit board (PCB) industry continues to evolve towards high-density interconnects, miniaturized structures, and multilayer stacking, the aspect ratio (AR) in product design has increased dramatically from the traditional 10:1 to 20:1 or even higher. This trend places more stringent requirements on the uniformity of the electroplated copper layer thickness. To improve the uniformity of the overall plating, the industry has gradually introduced insoluble anode technology to avoid the adverse effects on the uniformity of current distribution caused by the generation of negative reaction products (such as anode sludge or oxidation byproducts) during the electroplating process using traditional soluble copper balls.

[0003] However, according to basic electrochemical principles, to ensure sufficient electroplating efficiency, the anode conductive area required for the entire PCB board typically needs to be 1.5 to 2.0 times the area of ​​the PCB board being plated. In actual production, when using soluble copper balls as the anode, the copper balls are filled within a titanium basket, and their spherical shape naturally forms a porous stacked structure, effectively increasing the effective conductive surface area of ​​the anode and easily meeting the aforementioned area ratio requirement. In contrast, currently used insoluble anodes, such as those with a titanium mesh substrate, are usually used in conjunction with copper oxide powder dissolution processes. Their anode-to-PCB board area ratio can only be maintained at around 1:1 to 1.2:1, far below the ideal range. This significant deficiency in the anode conductive area directly limits the current distribution density in the output section, preventing the current from forming a sufficiently concentrated and effective transmission path on the board surface, thus reducing the overall electroplating efficiency. More importantly, an excessively small anode area weakens the deep plating capability of the electroplating solution, making it difficult to deposit copper layers inside high aspect ratio blind holes or through holes. This can easily lead to defects such as excessively thick plating at the hole opening and insufficient plating at the bottom of the hole, ultimately affecting the reliability and electrical performance of the product.

[0004] Therefore, how to overcome the problems of decreased electroplating efficiency and deteriorated deep plating capability caused by insufficient conductive area when using insoluble anodes to improve uniformity has become a technical problem that urgently needs to be solved in the field of PCB electroplating technology. Summary of the Invention

[0005] In view of the above problems, embodiments of the present invention provide a PCB electroplating method and apparatus to solve the problem of reduced electroplating efficiency and deterioration of deep plating capability caused by insufficient conductive area when using insoluble anodes to improve uniformity.

[0006] According to one aspect of the present invention, a PCB electroplating method is provided, the method comprising: Obtain a PCB board, wherein the PCB board is a single-layer core board or a multi-layer laminated board; The PCB board is drilled to create through holes or blind holes, and the PCB board is then cleaned for the first time. The PCB board is placed in an electroplating tank for electroplating treatment to form an electroplating layer on the surface and hole walls of the PCB board. Circuitry is fabricated on the electroplated layer of the PCB board to form connecting lines on the electroplated layer; The PCB board undergoes post-processing; The electroplating tank includes a main tank and at least one auxiliary tank, which is circulated with the main tank to increase the circulation of electroplating chemicals during the electroplating process.

[0007] In some embodiments, the main slot is provided with at least one first input terminal and at least one first output terminal, and the secondary slot is provided with a second input terminal and a second output terminal, wherein the second input terminal is connected to the first output terminal and the second output terminal is connected to the first input terminal.

[0008] In some embodiments, the electroplating solution circulation rate of the secondary tank is 8-9 TO.

[0009] In some embodiments, the number of secondary tanks is greater than three; the second output end of the secondary tank is connected to the first input end of the main tank via a filter device and a connecting pump.

[0010] In some embodiments, the electroplating solution comprises 40-70 g / L copper sulfate, 220-260 g / L sulfuric acid, and 0.3-1.0 ml / L brightener.

[0011] In some embodiments, during the electroplating process, the current ratio of the pulse waveform is 100:0:100:-300:-300:0, and the time ratio of the pulse waveform is 120:6.

[0012] In some embodiments, drilling is performed on the PCB board, specifically including: Through holes are created on the PCB board by mechanical drilling; Blind holes are created on the PCB board by laser drilling.

[0013] In some embodiments, circuit fabrication is performed on the electroplated layer of the PCB board, specifically including: After the PCB board is cleaned a second time, a photosensitive dry film is applied to the PCB board. Photopolymerization reaction is performed on the photosensitive dry film of the target area of ​​the PCB board using film data or LDI laser imaging from a preset circuit. The photosensitive dry film that has not undergone photopolymerization is dissolved using a developing solution; The PCB board is etched using an etching solution to remove the copper plating layer outside the target area of ​​the PCB board. The photosensitive dry film on the PCB board is stripped.

[0014] In some embodiments, the post-processing of the PCB board specifically includes: The PCB board is subjected to solder resist treatment, text processing, forming treatment, testing treatment, FQC treatment, tin melting treatment and surface cleaning treatment in sequence.

[0015] According to another aspect of the present invention, a PCB electroplating apparatus is provided for performing the PCB electroplating method described above.

[0016] The PCB electroplating method and apparatus of the present invention have the following advantages: By setting a main tank and at least one auxiliary tank in the electroplating tank for circulation connection, the present invention improves the circulation volume of electroplating solution, effectively enhances the flow of solution and ion transport capacity in holes with high aspect ratio, and solves the problem of uneven plating in the hole caused by insufficient anode conductive area. It not only improves the uniformity of plating in holes with high aspect ratio by increasing the circulation volume of electroplating solution, but also improves electroplating efficiency and product reliability.

[0017] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic flowchart of a PCB electroplating method according to an embodiment of the present invention is shown; Figure 2 A flowchart illustrating step S2 of an embodiment provided by the present invention is shown; Figure 3 A flowchart illustrating step S4 of an embodiment provided by the present invention is shown. Detailed Implementation

[0019] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0020] Example 1: Figures 1-3 This illustration shows a first embodiment of a PCB electroplating method provided by the present invention, which addresses the problem of decreased electroplating efficiency and deteriorated deep plating capability caused by insufficient conductive area when using an insoluble anode to improve uniformity. The method includes: S1. Obtain a PCB board, which may be a single-layer core board or a multi-layer laminated board. In step S1, PCB substrates conforming to specifications can be directly purchased from a supplier. These substrates can be pre-manufactured single-layer core boards or multi-layer boards that have undergone preliminary lamination. Alternatively, the required PCB board can be prepared internally through processes such as cutting and laminating raw materials. After obtaining these PCB boards, they typically require preliminary quality checks to ensure they meet the requirements of subsequent processing.

[0021] S2 involves drilling holes in the PCB board to create through-holes or blind vias, followed by a first cleaning process. In step S2, a conventional mechanical drill bit is used to drill the PCB board to create through-holes that penetrate the entire thickness of the board. Alternatively, a high-precision drilling machine can be used to create blind vias that do not penetrate the board thickness on a specific layer of the PCB board. After drilling, drill chips, dust, and other impurities will remain on the surface of the PCB board and the hole walls. Therefore, a first cleaning process is required, such as using physical methods like high-pressure water washing, brushing, or ultrasonic cleaning, to remove these deposits and provide a clean surface for subsequent electroplating.

[0022] In step S3, the PCB board is placed in an electroplating tank for electroplating to form an electroplated layer on the surface and hole walls of the PCB board. In step S3, the cleaned PCB board is fixed on a fixture and then immersed in the electroplating tank containing electroplating solution. By applying an external current, metal ions in the electroplating solution are reduced and deposited on the surface and hole walls of the PCB board, forming a uniform electroplated layer. During the electroplating process, the circulation of the electroplating solution has a significant impact on the plating quality. As a preferred embodiment, the electroplating tank is constructed to include a main tank and at least one auxiliary tank. The main tank is the area where the main electroplating operation is performed, and the PCB board is typically placed there. The auxiliary tank serves as an auxiliary unit, its main function being to form a closed circulation loop with the main tank. This circulation connection can be achieved by installing pipes and pumps between the main tank and the auxiliary tank. For example, a pump can be installed to pump the electroplating solution from the main tank to the auxiliary tank, and then the solution from the auxiliary tank can be returned to the main tank by gravity or another pump. In this way, the electroplating solution flows continuously throughout the electroplating system, significantly increasing the circulation rate. This increased circulation helps maintain the uniformity of the solution composition and promotes a stable electroplating reaction, thereby improving the coating quality.

[0023] S4, circuit fabrication is performed on the electroplated layer of the PCB board to form connection lines. In step S4, a layer of photosensitive material is directly coated on the electroplated layer, and then a pattern corresponding to the preset circuit diagram is formed on the photosensitive material through photolithography processes such as exposure and development. Subsequently, the electroplated layer not protected by the photosensitive material is removed using etching solution, thereby forming the required connection lines. Another implementation method is to use screen printing technology to print anti-etch ink on the electroplated layer to form a circuit pattern, and then perform etching. After etching is completed, the photosensitive material or ink needs to be removed to expose the connection lines.

[0024] S5, Post-processing of the PCB Board: In step S5, the PCB board with formed circuitry undergoes surface treatment, such as tin plating, gold plating, or OSP (Organic Solder Protector) treatment, to protect the copper traces from oxidation and provide good solderability for subsequent component soldering. Subsequently, cutting, milling, and other shaping processes can be performed to divide the large PCB board into independent unit boards. Finally, electrical testing and visual inspection are conducted to ensure the product meets design requirements.

[0025] The electroplating tank includes a main tank and at least one auxiliary tank, which are circulated with the main tank to increase the circulation of electroplating chemicals during the electroplating process.

[0026] In steps S1-S5, this application constructs an electroplating tank comprising a main tank and at least one auxiliary tank, and circulates the auxiliary tank with the main tank, significantly increasing the circulation volume of the electroplating solution. This enhances the deep plating capability of the electroplating solution, effectively improving the uniformity of copper layer deposition inside high aspect ratio through-holes or blind holes, and avoiding the defect of excessively thick plating at the hole opening and insufficient plating at the bottom. This helps improve the overall electroplating efficiency and product reliability of the PCB board, overcoming the limitations of traditional insoluble anode technology in terms of deep plating capability. Example 2: Based on Example 1, the present invention provides a second embodiment of the PCB electroplating method to further describe the PCB electroplating method.

[0027] In some embodiments, the main slot is provided with at least one first input terminal and at least one first output terminal, and the secondary slot is provided with a second input terminal and a second output terminal, wherein the second input terminal is connected to the first output terminal and the second output terminal is connected to the first input terminal.

[0028] Specifically, the first input end of the main tank is the inlet for the electroplating solution to enter the main tank. Its function is to introduce the treated or replenished electroplating solution into the main tank to maintain the volume, concentration, and temperature of the solution within the main tank. There can be one or more first input ends, and their location and number can be optimized according to the size and shape of the main tank and the flow requirements of the solution. For example, they can be located at the bottom or sidewall of the main tank to promote uniform distribution of the solution. The first output end of the main tank is the outlet for the electroplating solution to flow out of the main tank. Its function is to draw the solution out of the main tank for circulation, filtration, heating, or cooling, and then transport it to the auxiliary tank. There can also be one or more first output ends, typically located at the top or sidewall of the main tank to ensure smooth flow of the solution and prevent excessively high solution levels.

[0029] Meanwhile, the second input end of the secondary tank is the inlet for the electroplating solution to enter the secondary tank. Its function is to receive the solution from the main tank and introduce it into the secondary tank for further circulation. The second output end of the secondary tank is the outlet for the electroplating solution to flow out of the secondary tank. Its function is to draw the solution out of the secondary tank and transport it back to the main tank, completing the solution circulation path.

[0030] By connecting the second input end of the auxiliary tank to the first output end of the main tank, the path of the chemical solution flowing from the main tank into the auxiliary tank is defined. Specifically, the chemical solution discharged from the main tank is guided to the inlet of the auxiliary tank through pipes or other flow guiding structures. This connection ensures that the chemical solution in the main tank can be effectively extracted and sent to the auxiliary tank for treatment or temporary storage, which is a key link in realizing the chemical solution circulation between the main and auxiliary tanks. Furthermore, by connecting the second output end of the auxiliary tank to the first input end of the main tank, the path of the chemical solution returning to the main tank after flowing out of the auxiliary tank is defined. Specifically, the chemical solution treated in the auxiliary tank is guided to the inlet of the main tank through pipes or other flow guiding structures. This connection ensures that the chemical solution treated in the auxiliary tank can be replenished to the main tank in a timely manner, maintaining the dynamic balance of the chemical solution in the main tank, thereby forming a complete and controllable chemical solution circulation loop.

[0031] The above technical solution clarifies the specific path and interface for the chemical circulation between the main tank and the auxiliary tank. The first output end of the main tank is connected to the second input end of the auxiliary tank, allowing the chemical solution in the main tank to be effectively drawn out and sent to the auxiliary tank. Simultaneously, the second output end of the auxiliary tank is connected to the first input end of the main tank, ensuring that the chemical solution treated in the auxiliary tank can flow back to the main tank in a timely and accurate manner. This clear input-output connection method constructs a closed and controllable chemical circulation loop, significantly improving the circulation efficiency and uniformity of the electroplating chemical solution. The orderly flow of the chemical solution between the main and auxiliary tanks avoids stagnation or excessive consumption in localized areas, thus helping to maintain the stability and uniformity of the electroplating chemical composition, reduce concentration gradients, and ultimately improve the uniformity, density, and overall quality of the PCB board electroplating layer.

[0032] In some embodiments, the circulation rate of the electroplating solution in the secondary tank is 8TO-9TO. Here, TO represents the number of times the electroplating solution in the secondary tank circulates within a preset time; 8TO means 8 circulations. The preset time can be 1 hour or 30 minutes, determined based on the size of the secondary tank and the content of the electroplating solution. By precisely limiting the circulation rate of the electroplating solution in the secondary tank to the range of 8TO to 9TO, this application effectively solves the problem of uneven distribution of the electroplating solution within the holes and on the surface of the PCB board. Specifically, with this optimized circulation rate, the electroplating solution can flow through various areas of the PCB board at an appropriate speed, especially inside deep holes and micro-holes, ensuring timely replenishment of metal ions and additives, thereby significantly reducing the concentration difference inside and outside the holes and effectively suppressing concentration polarization. This allows the electroplated layer to achieve highly uniform deposition on the PCB board surface, hole walls, and inside the holes, avoiding defects such as thin plating inside holes, poor hole filling, or uneven plating on the board surface caused by insufficient circulation. Meanwhile, this circulation range also avoids the negative impacts of excessive chemical turbulence, bubble entrapment, rapid additive consumption, and unnecessary energy increases caused by excessive circulation. Therefore, by precisely controlling the circulation volume of the electroplating solution in the sub-tank, this application achieves stability and economy in the electroplating process while ensuring high quality and uniformity of the electroplated layer, thereby improving the overall electroplating performance and production efficiency of the PCB board.

[0033] In some implementations, the number of auxiliary tanks is greater than three; the second output end of the auxiliary tanks is connected to the first input end of the main tank via a filter and a connecting pump. By setting the number of auxiliary tanks to more than three, the processing capacity and flexibility of the electroplating system are significantly improved, better adapting to large-scale production or diverse process requirements. Simultaneously, by installing a filter and connecting pump between the second output end of the auxiliary tank and the first input end of the main tank, the electroplating solution is ensured to be fully purified before circulating back to the main tank. The filter effectively removes impurities and particles from the solution, maintaining its high purity and avoiding electroplating defects caused by impurities, thus ensuring the quality and uniformity of the PCB board electroplating layer. The connecting pump provides stable power, ensuring that the solution can efficiently and continuously pass through the filter and return to the main tank, maintaining the dynamic balance of the entire circulation system and the consistency of the solution concentration. This configuration is particularly suitable for multi-auxiliary tank systems, effectively solving the problems of decreased solution purity and insufficient circulation efficiency that may be caused by large solution circulation volumes and complex circulation paths, thereby significantly improving the stability of the electroplating process and product yield. In some embodiments, the electroplating solution includes 40-70 g / L copper sulfate, 220-260 g / L sulfuric acid, and 0.3-1.0 ml / L brightener. Specifically, the electroplating solution is the core medium of the electroplating process, and its composition and concentration directly determine the supply of metal ions, the conductivity of the electrolyte, and the physicochemical properties of the electroplated layer. The electroplating solution used in this application has been optimized to ensure high-quality deposition of the electroplated layer. Copper sulfate is the main source of copper ions in the electroplating solution, providing the metal ions required for copper deposition on the PCB board surface and hole walls. Its concentration range is set at 40-70 g / L to balance the electroplating speed and the quality of the electroplated layer. If the copper sulfate concentration is too low, the electroplating speed may be slow and the deposition ability within the holes may be poor; if the concentration is too high, it may lead to coarse crystals in the electroplated layer or even scorching. Within this concentration range, a sufficient supply of copper ions can be ensured while maintaining a good deposition rate and uniformity. Sulfuric acid in electroplating solutions primarily acts as a supporting electrolyte, providing good conductivity and inhibiting the hydrolysis of copper sulfate to prevent the formation of copper hydroxide precipitate. Its concentration range of 220-260 g / L helps maintain the stability and acidity of the electroplating solution, thereby promoting the effective transport and uniform deposition of copper ions. An appropriate sulfuric acid concentration also helps refine the grains, improving the density and ductility of the electroplated layer. A brightening agent is an organic additive used to improve the surface gloss, smoothness, and in-pore deposition ability of the electroplated layer. Its addition amount is 0.3-1.0 ml / L, which effectively inhibits excessive copper grain growth, promotes the formation of a fine, bright copper layer, and improves the coverage and uniformity of the electroplated layer on the pore walls. By precisely controlling the composition and concentration of the electroplating solution—including specific ranges of copper sulfate, sulfuric acid, and brighteners—the electroplating effect on PCB boards can be significantly optimized. Specifically, this formulation ensures a stable supply and efficient transport of copper ions during the electroplating process, resulting in a dense, uniform, and highly ductile electroplated layer on the PCB board surface and hole walls. The appropriate concentration of copper sulfate ensures a reasonable electroplating speed and in-hole deposition capacity; the addition of sulfuric acid maintains the stability and conductivity of the electrolyte and helps refine the grains; and the precise addition of brighteners effectively improves the gloss, smoothness, and uniformity of in-hole deposition in the electroplated layer. This optimized electroplating solution formulation effectively solves problems that may occur in traditional electroplating, such as uneven plating thickness, insufficient in-hole deposition, and surface roughness, thereby improving the overall quality and reliability of PCB boards and contributing to increased production efficiency and yield. In some embodiments of step S2, during the electroplating process, the current ratio of the pulse waveform is 100:0:100:-300:-300:0, and the time ratio of the pulse waveform is 120:6. Specifically, the current ratio of the pulse waveform is set to 100:0:100:-300:-300:0. This current ratio represents a multi-stage pulse current waveform, in which the forward current (e.g., 100) is used to drive metal ions to deposit on the PCB board surface and hole walls, promoting the growth of the electroplated layer; the zero current (e.g., 0) is the off-time, during which metal ions in the electrolyte can fully diffuse into the deep holes, while allowing the internal stress of the electroplated layer to be released, which helps to improve the density of the plating layer; the reverse current (e.g., -300) is used to selectively dissolve part of the deposited metal, especially the excessively thick plating layer at the hole opening or sharp corner, thereby achieving a micro-leveling effect and helping to remove impurities adsorbed on the plating surface, improving the plating uniformity and the filling capacity of the holes. This complex pulse waveform allows for more precise control of the metal ion transport and deposition process. Simultaneously, the time ratio of the pulse waveform is set to 120:6. This time ratio refers to the relative proportion of the durations of different current phases within the pulse cycle; for example, a forward current phase lasts 120 time units, while one or more subsequent reverse or off phases last a total of 6 time units. Precise control of the time ratio is crucial for optimizing electroplating results. A longer forward pulse time promotes rapid deposition, while appropriate off or reverse pulse times ensure that metal ions fully diffuse into the deep holes, finely finishing the coating, preventing buildup at the hole openings, and promoting uniform filling within the holes. By adjusting the time ratio, the electroplating rate, coating uniformity, and hole filling effect can be balanced.

[0034] By employing specific pulse waveform current and time ratios, this application significantly optimizes the metal deposition behavior during the electroplating process of PCB boards. The forward current phase ensures a sufficient metal deposition rate, while the zero current turn-off time provides ample diffusion time for metal ions in the electrolyte, enabling them to effectively reach the interior of deep holes and allowing the internal stress of the plating layer to be released, thereby improving the density of the plating layer. More importantly, the reverse current phase can selectively dissolve excessively thick plating layers at the orifice or protrusions on the board surface, achieving a microscopic leveling effect and effectively removing impurities adsorbed on the plating surface, thus avoiding common problems in traditional electroplating such as orifice buildup, weak plating layers at the center of holes, and voids. This precisely controlled pulse electroplating scheme results in a more uniform and dense plating layer on the PCB board surface and hole walls, especially in high aspect ratio through holes or blind holes, achieving excellent hole filling effects and significantly improving the electrical connection reliability and overall product quality of the PCB board.

[0035] In some implementations, the PCB board is drilled, see [link to relevant documentation]. Figure 2Specifically, it includes: S21, through-holes are made on the PCB board by mechanical drilling; S22, blind holes are created on the PCB board by laser drilling.

[0036] In steps S21-S22, through-holes are created on the PCB board by mechanical drilling. This refers to using a high-speed rotating drill bit to physically cut the PCB board, forming holes that penetrate through the layers of the PCB board or between specific layers. Mechanical drilling is a mature and widely used drilling technology in PCB manufacturing. The equipment typically includes a high-precision drilling machine, carbide drill bits, a precise positioning system, and an automated control unit. During the process, the PCB board is precisely fixed on the worktable, and the drill bit drills at preset coordinate points with specific rotational speeds and feed rates. Key process parameters, such as drill diameter, rotational speed, feed rate, and drilling depth, must be precisely controlled according to the PCB board material, thickness, and through-hole size requirements to ensure the smoothness of the hole walls and the accuracy of the hole diameter.

[0037] Creating blind vias on a PCB board using laser drilling involves using a high-energy laser beam to ablate or vaporize the PCB material, forming holes that do not completely penetrate the PCB. Laser drilling is a non-contact processing technology, particularly suitable for creating high-precision, small-diameter blind vias, especially in the manufacture of high-density interconnect (HDI) PCBs. Laser drilling equipment typically includes a laser (such as a CO2 laser, UV laser, or ultrafast laser), an optical focusing and scanning system, a high-precision motion platform, and advanced control software. During the process, the laser beam is precisely focused onto the PCB surface through the optical system and scans along a preset path and depth. By precisely controlling the laser power, pulse width, frequency, and scanning speed, precise control over the depth and diameter of the blind vias can be achieved, avoiding damage to underlying circuitry and ensuring the quality of the via walls.

[0038] In some embodiments of step S4, circuit fabrication is performed on the electroplated layer of the PCB board, see [link to relevant documentation]. Figure 3 Specifically, it includes: S41, after the second cleaning of the PCB board, a photosensitive dry film is applied to the PCB board. In step S41, the second cleaning aims to thoroughly remove any contaminants such as oxides, residues, oil, or fingerprints that may be present on the surface of the electroplated layer, ensuring a clean PCB board surface and providing a foundation for good adhesion of the subsequent photosensitive dry film. The cleaning process can combine chemical cleaning (e.g., immersion or spraying with a weak acid or weak alkali solution) with physical cleaning (e.g., brushing or high-pressure water rinsing) to achieve the best cleaning effect. After cleaning, the photosensitive dry film is adhered to the surface of the electroplated layer of the PCB board. The photosensitive dry film is a polymer film with photosensitive properties, which is usually uniformly adhered to the surface of the PCB board under certain temperature and pressure using lamination equipment, ensuring that there are no air bubbles and that the dry film is tightly bonded to the copper layer, forming a uniform protective layer.

[0039] S42, using pre-set circuit film data or LDI laser imaging, a photopolymerization reaction is performed on the photosensitive dry film in the target area of ​​the PCB board. In step S42, if film data is used, a pre-made transparent film with circuit patterns is used as a mask, precisely aligned with the PCB board to which the photosensitive dry film is applied, and then irradiated with ultraviolet light. The ultraviolet light passes through the transparent area of ​​the film, causing the photosensitive dry film to undergo a photopolymerization reaction and solidify in that area, forming an etch-resistant protective layer; the opaque area of ​​the film blocks the ultraviolet light, keeping the photosensitive dry film in an unpolymerized state. If LDI laser imaging is used, no film is needed; instead, a high-precision laser beam directly scans the surface of the photosensitive dry film, selectively exposing the photosensitive dry film according to the digitized circuit pattern data, causing it to undergo a photopolymerization reaction. LDI technology has advantages such as high precision, high efficiency, and flexible design modification, and is especially suitable for the manufacturing of high-density, fine-line PCBs.

[0040] In step S43, the photosensitive dry film that has not undergone photopolymerization is dissolved using a developing solution. In step S43, the developing solution is typically a weakly alkaline solution, such as a sodium carbonate solution. The exposed PCB board is immersed in the developing solution. The photosensitive dry film that has not undergone photopolymerization (i.e., the dry film in the unexposed areas) is dissolved and washed away by the developing solution, thereby exposing the underlying copper plating layer. The photosensitive dry film that has undergone photopolymerization (i.e., the dry film in the exposed areas) remains on the PCB board surface, forming a protective layer consistent with the preset circuit pattern.

[0041] In step S44, the PCB board is etched using an etching solution to remove the copper plating outside the target area. The etching solution in step S44 is typically an acidic etching solution, such as ferric chloride solution, copper chloride solution, or ammonium persulfate solution. The PCB board is immersed in the etching solution, and the copper plating not protected by the photosensitive dry film reacts chemically with the etching solution and is dissolved and removed. The copper plating protected by the photosensitive dry film remains, forming the required interconnections. The etching process requires precise control of the solution concentration, temperature, and etching time to ensure the accuracy of the line width and spacing, avoiding over-etching or under-etching.

[0042] S45, the photosensitive dry film on the PCB board is stripped. In step S45, the stripping process aims to remove the protective layer of the photosensitive dry film that has completed the etching process, fully exposing the final copper traces. The stripping process typically uses a strongly alkaline solution, such as sodium hydroxide solution or a specialized stripping solution. The PCB board is immersed in the stripping solution, and the cured photosensitive dry film is dissolved or peeled off, exposing the copper layer beneath the formed traces. After stripping, only the required copper interconnect traces remain on the surface of the PCB board.

[0043] In steps S41-S45, through the detailed circuit fabrication steps described above, this application achieves high-precision circuit pattern transfer and formation. First, the second cleaning process ensures good adhesion of the photosensitive dry film, laying the foundation for subsequent photolithography. Next, photopolymerization is performed using film data or LDI laser imaging technology, accurately transferring the pre-set fine circuit pattern onto the photosensitive dry film, effectively avoiding circuit deviations caused by traditional manual or low-precision methods. Subsequently, through development and etching processes, unwanted copper plating layers are precisely removed, forming clear connection lines free of short circuits or open circuit defects. The final film removal process exposes the complete circuit pattern. This refined circuit fabrication process significantly improves the circuit accuracy and reliability of the PCB board, especially suitable for the manufacturing needs of high-density, high-integration PCBs, thereby ensuring the electrical performance and stability of the final product. In some embodiments of step S5, post-processing of the PCB board is performed, specifically including: sequentially performing solder resist treatment, text processing, forming treatment, testing treatment, FQC treatment, tinning treatment, and surface cleaning treatment on the PCB board. Through the above technical solution, a series of systematic and standardized post-processing steps are introduced after the PCB board completes electroplating and circuit fabrication. Solder resist treatment effectively protects the circuitry, preventing short circuits and environmental corrosion; text processing provides necessary identification information for easy assembly and maintenance; forming treatment ensures that the physical dimensions and shape of the PCB board meet requirements; testing treatment verifies the functional integrity of the PCB board from an electrical perspective; FQC treatment, as the final quality control step, ensures that the product appearance and quality meet standards; tinning treatment provides excellent solderability for subsequent soldering and prevents copper oxidation; and surface cleaning treatment thoroughly removes residues from the production process, ensuring the electrical reliability and cleanliness of the PCB board. The sequential implementation of these steps constitutes a complete PCB board finishing process, which significantly improves the final product quality, reliability, and lifespan of the PCB board, enabling it to meet the stringent application requirements of electronic products and effectively solving the problems of unstable product quality and functional defects that may result from only performing general "post-processing".

[0044] Example 3: Based on Embodiment 1 or Embodiment 2, the present invention provides an embodiment of a PCB electroplating apparatus, which is used to perform the PCB electroplating method of Embodiment 1 or Embodiment 2.

[0045] This invention combines the main tank and the auxiliary tank in a circulating manner, thereby significantly increasing the circulation volume of the electroplating solution and effectively improving the uniformity of copper layer deposition in high aspect ratio holes, thus enhancing electroplating efficiency and product reliability. Due to the increased circulation volume, the composition distribution of the electroplating solution is more uniform, and the current distribution density on the board surface is optimized, resulting in more consistent copper layer deposition inside high aspect ratio blind or through holes. Specifically, the circulation volume of the electroplating solution in the auxiliary tank is configured to 8TO-9TO, a parameter range that has been experimentally verified to effectively maintain the stability of the solution composition. Simultaneously, the electroplating solution includes 40-70 g / L copper sulfate, 220-260 g / L sulfuric acid, and 0.3-1.0 ml / L brightener; the precise proportions of these components further ensure the quality of the plating layer. During the electroplating process, a pulse waveform with a current ratio of 100:0:100:-300:-300:0 and a pulse waveform with a time ratio of 120:6 is used. This combination of parameters helps to control the coating thickness distribution and is especially suitable for uniform deposition of high aspect ratio structures.

[0046] Through the above technical solutions, this PCB electroplating apparatus effectively overcomes the limitations of traditional insoluble anode technology in terms of insufficient conductive area. The increased chemical circulation indirectly enhances the deep plating capability of the electroplating solution, avoiding the defect of excessively thick plating at the hole opening and insufficient plating at the bottom. Furthermore, in the PCB drilling process, through-holes are created through mechanical drilling or blind holes are created through laser drilling, combined with a first cleaning process to remove drill debris and impurities, providing a clean substrate for subsequent electroplating. The circuit fabrication stage employs steps such as applying photosensitive dry film, photopolymerization reaction, development and dissolution, and etching to ensure the precise formation of interconnecting circuits. The post-processing stage sequentially performs solder resist treatment, text processing, shaping, testing, FQC treatment, tinning, and surface cleaning, comprehensively improving the reliability and electrical performance of the PCB. Overall, by optimizing the chemical circulation system, this apparatus significantly improves the electroplating quality of high-density interconnect PCBs, meeting the industry's stringent requirements for miniaturized structures and multi-layer stacking. Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into the detailed description, wherein each claim itself is a separate embodiment of the invention.

[0047] Those skilled in the art will understand that the modules in the devices of the embodiments can be adaptively changed and placed in one or more devices different from those in the embodiments. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.

[0048] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several systems, several of these systems may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A PCB electroplating method, characterized in that, The method includes: Obtain a PCB board, wherein the PCB board is a single-layer core board or a multi-layer laminated board; The PCB board is drilled to create through holes or blind holes, and the PCB board is then cleaned for the first time. The PCB board is placed in an electroplating tank for electroplating treatment to form an electroplating layer on the surface and hole walls of the PCB board. Circuitry is fabricated on the electroplated layer of the PCB board to form connecting lines on the electroplated layer; Post-processing is performed on the PCB board; The electroplating tank includes a main tank and at least one auxiliary tank, which is circulated with the main tank to increase the circulation of electroplating chemicals during the electroplating process.

2. The PCB electroplating method according to claim 1, characterized in that, The main slot is provided with at least one first input terminal and at least one first output terminal, and the secondary slot is provided with a second input terminal and a second output terminal. The second input terminal is connected to the first output terminal, and the second output terminal is connected to the first input terminal.

3. The PCB electroplating method according to claim 2, characterized in that, The circulation rate of the electroplating solution in the secondary tank is 8-9 TO.

4. The PCB electroplating method according to claim 2, characterized in that, The number of auxiliary tanks is greater than 3; the second output end of the auxiliary tank is connected to the first input end of the main tank through a filter device and a connecting pump.

5. The PCB electroplating method according to claim 1, characterized in that, The electroplating solution includes 40-70 g / L copper sulfate, 220-260 g / L sulfuric acid, and 0.3-1.0 ml / L brightener.

6. The PCB electroplating method according to claim 1, characterized in that, In the electroplating process, the current ratio of the pulse waveform is 100:0:100:-300:-300:0, and the time ratio of the pulse waveform is 120:

6.

7. The PCB electroplating method according to claim 1, characterized in that, Drilling is performed on the PCB board, specifically including: Through holes are created on the PCB board by mechanical drilling; Blind holes are created on the PCB board by laser drilling.

8. The PCB electroplating method according to claim 1, characterized in that, The circuit fabrication is performed on the electroplated layer of the PCB board, specifically including: After the PCB board is cleaned a second time, a photosensitive dry film is applied to the PCB board. Photopolymerization reaction is performed on the photosensitive dry film of the target area of ​​the PCB board using film data or LDI laser imaging from a preset circuit. The photosensitive dry film that has not undergone photopolymerization is dissolved using a developing solution; The PCB board is etched using an etching solution to remove the copper plating layer outside the target area of ​​the PCB board. The photosensitive dry film on the PCB board is stripped.

9. The PCB electroplating method according to claim 1, characterized in that, The post-processing of the PCB board specifically includes: The PCB board is subjected to solder resist treatment, text processing, forming treatment, testing treatment, FQC treatment, tinning treatment and surface cleaning treatment in sequence.

10. A PCB electroplating apparatus, characterized in that, The apparatus is used to perform the PCB electroplating method according to any one of claims 1-9.

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