A PCB blind hole silver filling device and silver filling method

Abstract

The application discloses a PCB blind hole silver filling device and method, and relates to the technical field of PCB electroplating, which comprises a positioning base arranged at the middle line position of the bottom of an electroplating tank, a positioning hanging base arranged at the top of the electroplating tank in a detachable manner and used for clamping a circuit board to be plated with silver, a side spray pipe arranged vertically along the depth direction of the electroplating tank and used for spraying silver plating liquid towards the circuit board, a bottom spray pipe arranged horizontally and transversely to the electroplating tank and used for spraying silver plating liquid obliquely upwards to enhance liquid disturbance, a movable spray pipe which can move along the length direction of the electroplating tank and rotate around its own axis and is used for spraying silver plating liquid to the side surface of the circuit board in a fan shape and into the blind hole, and a plurality of groups of spray pipes which are connected with liquid supply pipes of the electroplating tank and used for cooperatively supplying silver plating liquid. Through the multi-directional spraying and dynamic rotating silver spraying mechanism, a composite flow field circulation is formed in the blind hole, the uniformity and compactness of silver layer deposition in the circuit board and the blind hole are improved, and the problems of limited liquid flow and uneven silver layer in the existing electroplating of the blind hole of the circuit board are solved.

Description

Technical Field

[0001] This invention relates to the field of PCB electroplating technology, and in particular to a device and method for filling silver in blind holes of PCBs. Background Technology

[0002] Printed Circuit Boards (PCBs) serve as a crucial foundation for connecting electronic components and transmitting signals; their conductivity and reliability directly impact the performance and stability of the entire product. To achieve multi-layer wiring and high-density interconnects within a limited space, modern High-Density Interconnect (HDI) technology widely employs micro-blind via structures to achieve inter-layer electrical connections. Blind vias are typically formed through laser drilling or mechanical drilling, and then filled with metal during the electroplating process to create conductive pathways. Silver, due to its excellent conductivity and oxidation resistance, is widely used in the metallization process of vias in high-end PCBs.

[0003] Existing blind via silver filling technology mainly involves electroplating or chemical displacement processes. These processes often employ a tank-type electroplating structure, combined with vibration, oscillation, or ultrasonic assistance to promote electrolyte circulation within the blind via and enhance the silver ion deposition rate. However, due to the small diameter and large depth-to-diameter ratio of blind vias, and the limited fluid exchange within the vias, vibration or oscillation methods often only improve the surface electric field distribution and are insufficient to achieve adequate silver coating on the inner wall of the blind via. This can easily lead to problems such as local dead zones, uneven silver layer thickness, or insufficient deposition at the bottom of the via, affecting the conductivity consistency and welding reliability of the through-hole.

[0004] In addition, some existing improvement solutions attempt to optimize the current distribution by changing the electrode layout or adding auxiliary anodes, but it is still difficult to accurately control the flow field and electric field inside the tiny blind holes. Especially in the complex structure of multilayer PCBs, the traditional vertical electroplating liquid flow method cannot fully enter the bottom area of ​​the hole, resulting in low silver deposition efficiency and insufficient coverage at the bottom and sidewalls of the blind hole, which leads to subsequent fluctuations in electrical performance and a decrease in reliability.

[0005] To address the aforementioned shortcomings, companies have introduced side-spray silver filling equipment into their production processes. By installing multi-angle side-spray nozzles within the electroplating tank, the silver solution is sprayed with high kinetic energy onto the sidewalls and bottom areas of blind vias on the PCB board, significantly improving the liquid turnover rate and the uniformity of silver ion distribution within the blind vias. This method has demonstrated higher silver layer density and coverage within the vias in experiments, becoming an important development direction for precision silver filling processes for blind vias. However, current side-spray structures still suffer from problems such as difficulty in precisely controlling the spray angle, uneven spray pressure distribution, and a high risk of nozzle clogging. A systematic and controllable silver filling device and supporting methods have not yet been developed.

[0006] In summary, the existing technology has at least the following technical problems:

[0007] Existing silver filling equipment for blind vias on circuit boards suffers from technical problems such as restricted electrolyte flow within the vias and uneven silver deposition. Summary of the Invention

[0008] The purpose of this invention is to provide a device and method for filling silver in blind holes of PCB boards, so as to solve the technical problems of restricted electrolyte flow and uneven silver deposition in existing blind hole silver filling equipment for PCB boards.

[0009] The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0010] To address the aforementioned technical problems, the present invention provides the following technical solution:

[0011] This invention provides a device for filling blind vias with silver in PCB boards, comprising an electroplating tank, a positioning base, a positioning hanger, side spray pipes, a bottom spray pipe, and a movable spray pipe. The positioning base is located at the bottom centerline of the electroplating tank, and the positioning hanger is detachably located at the top centerline of the electroplating tank. The positioning base is used to position and hold the bottom of the PCB to be silver-plated, and the positioning hanger is used to position and hold the top of the PCB. The side spray pipes are arranged vertically along the depth direction of the electroplating tank, and multiple side spray pipes are arranged along the length direction of the electroplating tank, spraying silver plating liquid towards the side of the PCB. The length direction of the bottom spray pipe is parallel to the horizontal direction of the electroplating tank. The side spray nozzles are arranged parallel to each other at the bottom of the electrolytic tank and multiple nozzles are arranged along the length of the electroplating tank. The bottom spray nozzles spray silver plating solution at an angle upward toward the side of the circuit board in a controllable rhythm to increase the turbulence of the liquid in the tank. The moving spray nozzles are suspended in the electroplating tank in a movable manner and move along the length of the electroplating tank while rotating around their own axis at a controllable speed, throwing the silver plating solution onto the side of the circuit board and extending into the blind holes. The moving spray nozzles are arranged between the circuit board and the side spray nozzles. The moving spray nozzles, the multiple side spray nozzles, and the bottom spray nozzles are all connected to the liquid supply pipe of the electroplating tank to receive the supply of silver plating solution.

[0012] Preferably, the bottom of the circuit board is inserted into the positioning base along with the positioning bracket installed on the electroplating tank, thereby fixing the circuit board in the electroplating tank.

[0013] Preferably, the side spray pipe is provided with a plurality of 60-degree first tapered nozzles in the electrolytic cell from top to bottom along the length direction, and the first tapered nozzles are arranged facing the circuit board.

[0014] Preferably, a control valve for controlling the injection rhythm is installed between the first tapered nozzle and the side spray pipe.

[0015] Preferably, the bottom spray pipe is arranged with a plurality of second tapered nozzles of 30 degrees along its length, and the second tapered nozzles are oriented toward the circuit board.

[0016] Preferably, four second tapered nozzles are arranged on the bottom spray pipe, which are arranged at an angle of 65 degrees, 55 degrees, 45 degrees and 35 degrees upward in sequence along the side wall of the electrolytic cell to the side of the circuit board, and the ends of the four second tapered nozzles are on the same inclined plane.

[0017] Preferably, above the electrolytic cell, a linear moving module is provided, which is arranged along the length of the electrolytic cell; the moving slider of the linear moving module moves along the length of the electrolytic cell; the moving nozzle is fixed on the moving slider, and the linear moving module drives the moving nozzle to move along the length of the electrolytic cell.

[0018] Preferably, the linear motion module drives the moving slider to move along the length direction of the electrolytic cell via a transmission structure that drives a lead screw nut with a servo motor.

[0019] Preferably, a rotating unit is installed on the movable slider. The rotating unit includes a rotating base, a rotating motor, and a rotating ring. A hollow cantilever extends outward from the movable slider from the rotating base. Planar bearings are installed at the top and bottom of the hollow cantilever, and the rotating ring is sleeved between the two planar bearings. The inner ring of the rotating ring has a keyway. The movable nozzle passes through the inner ring of the rotating ring and extends into the electrolytic cell. The fixed end of the movable nozzle has protruding key teeth that are bonded to the keyway for fixation. The outer ring of the rotating ring has transmission teeth. The rotating motor is mounted on the rotating base. A transmission gear is installed on the output shaft of the rotating motor. The transmission gear meshes with the rotating ring for transmission. The rotating motor drives the rotating ring to move the movable nozzle back and forth to the left, front, and right sides of the circuit board, causing the silver plating solution to be thrown out in a fan shape.

[0020] Preferably, the liquid supply pipe is connected to the top of the fixed end of the movable nozzle, so that the silver plating liquid flows into the movable nozzle from top to bottom; the movable nozzle is provided with a plurality of 15-degree third tapered nozzles from top to bottom along its own length direction, and the third tapered nozzles are arranged facing the circuit board.

[0021] A method for filling blind vias with silver in a PCB board is also provided, implemented using a PCB board blind via silver filling device, including the following steps:

[0022] S1. Workpiece preparation: After pre-cleaning and surface activation treatment, the circuit board is installed between the positioning base and the positioning hanger in the electroplating tank.

[0023] S2. Liquid circulation and spray initialization: Turn on the liquid supply of the electroplating tank to allow the silver plating solution to be supplied synchronously from the side spray pipe, bottom spray pipe and moving spray pipe and start spraying.

[0024] S3, Multi-angle side spray uniform distribution stage: Control the first tapered nozzle in the side spray pipe to spray sequentially in a layered rhythm from top to bottom, so that the silver plating liquid covers the side wall of the blind hole and the hole area of ​​the circuit board with different incident angles, forming a stable circulation distribution.

[0025] S4, Dynamic Movement and Rotation Silver Spraying Stage: The linear movement module and rotation unit are activated to drive the moving nozzle to move along the length of the electroplating tank and rotate around its own axis at a controllable speed.

[0026] By adjusting the reciprocating frequency and rotational angular velocity of the moving nozzle, and periodically strengthening the silver spraying of blind holes in different areas;

[0027] S5. Synchronous Electroplating Control Stage: During the silver spraying process, in conjunction with the real-time detection modules for current density, temperature and liquid flow rate installed in the electroplating tank, the spray flow rate and spray rhythm of the side spray pipe and bottom spray pipe, as well as the spray flow rate and movement rhythm of the moving spray pipe, are dynamically adjusted based on the multi-point current feedback signals in the electrolytic tank.

[0028] When the deviation of the blind hole current density exceeds the set threshold, the moving nozzle automatically optimizes the injection pressure and rotation angle.

[0029] S6. Post-processing and quality inspection: After stopping the liquid supply, take out the silver-plated circuit board and perform rinsing, drying and silver layer thickness inspection in sequence.

[0030] The beneficial effects of this invention are as follows:

[0031] To address the technical problems of restricted electrolyte flow and uneven silver deposition in existing blind via silver filling equipment for circuit boards, the provided PCB blind via silver filling device has the following technical advantages:

[0032] (1) Multi-directional injection structure significantly improves fluid circulation inside blind holes.

[0033] By setting side spray pipes, bottom spray pipes and movable spray pipes in the electroplating tank, a three-dimensional multi-directional jet flow structure is formed, which causes the silver plating solution to form a turbulent circulation on the surface of the circuit board and causes the silver plating solution to enter the blind hole to form a spiral flow. This effectively breaks through the limitations of the traditional vertical flow field mode, significantly improves the renewal rate of the electrolyte in the hole and the ion exchange efficiency, and solves the problem of liquid stagnation inside the blind hole.

[0034] (2) Controllable rhythmic spraying and dynamic disturbance improve the uniformity of silver deposition.

[0035] The bottom spray nozzles use 30-degree tapered nozzles arranged at multiple angles, spraying upwards at angles of 65°, 55°, 45°, and 35°. Through rhythmic spray control, liquid pulsation disturbance is achieved, making the silver ion concentration distribution in the bottom and edge areas of the blind holes on the circuit board more even, ensuring that the silver layer thickness at the bottom and wall of the hole is consistent and the silver layer is highly dense. At the same time, the bottom spray nozzles can reduce the phenomenon of air bubbles at the bottom of the electroplating tank, avoiding air bubbles from affecting the uniformity of silver layer deposition.

[0036] (3) The moving nozzle enables dynamic rotational silver spraying, forming a full-coverage sedimentation field.

[0037] The moving nozzle is driven by a linear moving module to move along the length of the electroplating tank, and is driven by a rotating unit to rotate controllably, so that the silver plating liquid is thrown out in a fan shape and extends into the blind hole, forming a multi-angle spray coverage, effectively filling the blind area in the spatial distribution of the side spray and bottom spray, and ensuring that the silver layer thickness in all directions inside the hole is uniform.

[0038] (4) Modular positioning design improves process stability and maintainability.

[0039] By setting up detachable positioning hangers and positioning bases, the PCB board can be quickly clamped and accurately positioned, ensuring that the nozzle jet covers the blind holes on the circuit board, improving the uniformity of the plating layer and avoiding translation phenomena. At the same time, this structure is easy to clean and maintain and is compatible with different specifications of circuit boards, improving the industrial adaptability of the device.

[0040] (5) Achieve synergistic optimization of electroplating solution flow field and jet flow.

[0041] By utilizing the synergistic effect of multiple nozzles, a stable composite flow field structure is formed within the electroplating tank, achieving a three-layer fluid control mode of "mainstream impact + secondary flow compensation + dynamic disturbance." This results in a higher silver deposition rate and greater plating uniformity within the holes at the same current density. This device can control the silver layer thickness difference within blind holes to within ±3%, significantly outperforming traditional vibration or oscillating electroplating equipment.

[0042] In summary, this invention not only effectively solves the technical problems of restricted electrolyte flow and uneven silver deposition inside blind vias, but also improves the overall plating uniformity of the circuit board through structural innovation and fluid control optimization, achieving a high-uniformity, high-density, and high-efficiency PCB blind via silver plating process. Attached Figure Description

[0043] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a partial top view of the PCB blind hole silver filling device of the present invention;

[0045] Figure 2 This is a partial top view of the linear motion module, rotating unit, and moving nozzle of the present invention.

[0046] Figure 3 This is a partial side view of the movable nozzle of the present invention.

[0047] Figure 4 This is a partial side view of the PCB blind hole silver filling device of the present invention;

[0048] Figure 5 This is a partial side view of the rotating unit and moving nozzle of the linear motion module of the present invention.

[0049] Figure 6 This is a schematic diagram of the steps of the PCB board blind via silver filling method of the present invention.

[0050] The reference numerals in the attached figures are as follows:

[0051] 1. Electroplating tank; 11. Liquid supply pipe;

[0052] 2. Positioning base;

[0053] 3. Positioning hanger;

[0054] 4. Side nozzle; 41. First tapered nozzle;

[0055] 5. Bottom nozzle; 51. Second tapered nozzle;

[0056] 6. Moving nozzle; 61. Fixed end; 611. Key tooth; 62. Third taper nozzle;

[0057] 7. Linear movement module; 71. Moving slider;

[0058] 8. Rotating unit; 81. Rotating base; 82. Rotary motor; 821. Transmission gear; 83. Rotating ring; 831. Keyway; 832. Transmission gear; 84. Surface bearing;

[0059] 9. Circuit board. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0061] The specific implementation provides a PCB board blind via silver filling device and method, including a positioning base located at the bottom centerline of the electroplating tank, a positioning hanger detachably located at the top of the electroplating tank for clamping the circuit board to be silvered; side spray pipes arranged vertically along the depth direction of the electroplating tank, spraying silver plating liquid towards the circuit board; bottom spray pipes arranged horizontally parallel to the electroplating tank, spraying silver plating liquid obliquely upward to enhance liquid turbulence; a movable spray pipe that can move along the length direction of the electroplating tank and rotate around its own axis, throwing the silver plating liquid in a fan shape towards the side of the circuit board and deep into the blind via; multiple sets of spray pipes connected to the liquid supply pipe of the electroplating tank for coordinated supply of silver plating liquid; through multi-directional spraying and dynamic rotation silver plating mechanism, a composite flow field circulation is formed in the blind via, improving the uniformity and density of silver layer deposition in the circuit board and blind via; effectively solving the technical problems of restricted electrolyte flow and uneven silver layer deposition in existing circuit board blind via silver filling equipment.

[0062] The first implementation of the PCB blind via silver filling device is as follows: Figure 1 and Figure 4 As shown, the system includes an electroplating tank 1, a positioning base 2, a positioning hanger 3, side spray pipes 4, a bottom spray pipe 5, and a movable spray pipe 6. The positioning base 2 is located at the bottom centerline of the electroplating tank 1, and the positioning hanger 3 is detachably located at the top centerline of the electroplating tank 1. The positioning base 2 is used to position and hold the bottom of the circuit board 9 to be silvered, and the positioning hanger 3 is used to position and hold the top of the circuit board 9. The side spray pipes 4 are arranged vertically along the depth direction of the electroplating tank 1, and multiple side spray pipes are arranged along the length direction of the electroplating tank 1. The side spray pipes 4 spray silver plating liquid towards the side of the circuit board 9. The length direction of the bottom spray pipe 5 is parallel to the transverse direction of the electroplating tank 1. Multiple nozzles are arranged at the bottom of the electrolytic cell and along the length of the electroplating tank 1. The bottom nozzle 5 sprays silver plating solution at an angle upward toward the side of the circuit board 9 in a controlled rhythm to increase the turbulence of the liquid in the tank. The movable nozzle 6 is suspended in the electroplating tank 1 in a movable manner and moves along the length of the electroplating tank 1 and rotates around its own axis at a controlled rotation speed, throwing the silver plating solution onto the side of the circuit board 9 and extending into the blind hole. The movable nozzle 6 is arranged between the circuit board 9 and the side nozzles 4. The movable nozzle 6, the multiple side nozzles 4, and the bottom nozzle 5 are all connected to the liquid supply pipe 11 of the electroplating tank 1 to receive the supply of silver plating solution.

[0063] Specifically, addressing the technical problems of limited electrolyte flow and uneven silver deposition in existing blind via silver filling equipment for circuit boards 9, the provided PCB blind via silver filling device has several technical advantages, including: a multi-directional spray structure that significantly improves fluid circulation inside the blind via; by setting side spray pipes 4, bottom spray pipes 5, and movable spray pipes 6 in the electroplating tank 1, a three-dimensional multi-directional spray structure is formed, causing the silver plating solution to form a turbulent circulation on the surface of the circuit board 9, and causing the silver plating solution to enter the blind via and form a spiral flow, effectively breaking through the limitations of the traditional vertical flow field mode, significantly improving the electrolyte renewal rate and ion exchange efficiency inside the via, and solving the problem of liquid stagnation inside the blind via.

[0064] Controllable rhythmic spraying and dynamic disturbance improve the uniformity of silver layer deposition. The bottom spray pipe 5 uses 30-degree tapered nozzles arranged at multiple angles, and sprays at oblique upward angles of 65°, 55°, 45° and 35°. The rhythmic spray flow control realizes liquid pulsation disturbance, which makes the silver ion concentration distribution in the bottom and edge areas of the blind holes on the circuit board 9 more uniform, ensuring that the silver layer thickness at the bottom of the hole and the hole wall is consistent and the silver layer is highly dense. At the same time, the bottom spray pipe can reduce the phenomenon of air bubbles at the bottom of the electroplating tank 1, and avoid air bubbles affecting the uniformity of silver layer deposition.

[0065] The moving nozzle 6 achieves dynamic rotational silver spraying, forming a full-coverage deposition field. The moving nozzle 6 is driven by the linear moving module 7 to move along the length of the electroplating tank 1, and is driven by the rotating unit 8 to rotate controllably, so that the silver plating liquid is thrown out in a fan shape and extends into the blind hole, forming a multi-angle spray coverage, effectively filling the blind area in the spatial distribution of side spray and bottom spray, and ensuring that the silver layer thickness in all directions inside the hole is uniform.

[0066] The modular positioning design enhances process stability and maintainability. By setting up detachable positioning hangers 3 and positioning bases 2, the PCB board can be quickly clamped and accurately positioned, ensuring that the nozzle jet covers the blind holes on the circuit board 9, improving the uniformity of the plating layer and avoiding translation phenomena. At the same time, this structure facilitates cleaning and maintenance and is compatible with different specifications of circuit boards 9, improving the industrial adaptability of the device.

[0067] This system achieves synergistic optimization of the electroplating solution flow field and the jet flow. Through the coordinated action of multiple nozzles, a stable composite flow field structure is formed within the electroplating tank 1, realizing a three-layer fluid control mode of "mainstream impact + secondary flow compensation + dynamic disturbance." This results in a higher silver deposition rate and higher plating uniformity within the holes at the same current density. This device can control the silver layer thickness difference within blind holes to within ±3%, which is significantly better than traditional vibration or oscillating electroplating equipment.

[0068] In summary, this invention not only effectively solves the technical problems of restricted electrolyte flow and uneven silver deposition inside blind holes, but also improves the overall plating uniformity of the circuit board 9 through structural innovation and fluid control optimization, realizing a PCB blind hole silver filling electroplating process with high uniformity, high density and high efficiency.

[0069] As one alternative implementation method:

[0070] Regarding the cooperative function of the aforementioned positioning bracket 3, positioning base 2, and circuit board 9, this embodiment is as follows: Figure 1 and Figure 4 As shown, the bottom of the circuit board 9 is inserted into the positioning base 2 along with the positioning bracket 3 installed on the electroplating tank 1, thus fixing the circuit board 9 in the electroplating tank 1.

[0071] In application, the positioning hanger 3 and the positioning base 2 work together to form a rigid clamp in the vertical direction for the circuit board 9 to be silvered, ensuring that the circuit board 9 maintains a stable vertical posture in the electroplating tank 1. This guarantees that the openings of each blind hole are accurately aligned with the side spray direction, preventing spraying deviations caused by board tilting or swaying. This structure not only improves the accuracy of silver liquid spraying from blind holes, but also helps to form a stable annular flow field with the side spray pipe 4 and the bottom spray pipe 5, achieving symmetrical flow distribution of the electrolyte inside the electroplating tank 1 and avoiding uneven film formation where one side has a thick film and the other side has a thin film.

[0072] In addition, the positioning bracket 3 is made of corrosion-resistant stainless steel or polytetrafluoroethylene material, and its clamping mechanism can be a flexible slot type or a threaded clamping type to adapt to circuit boards 9 of different thicknesses and sizes; the positioning base 2 integrates conductive contact terminals for connecting to the electroplating power supply to achieve a quick clamping and conductive integrated structure.

[0073] Regarding the specific jet structure of the aforementioned side nozzle 4, this embodiment is, for example... Figure 4 As shown, the side spray pipe 4 is provided with multiple 60-degree first tapered nozzles 41 in the electrolytic cell from top to bottom along the length direction, and the first tapered nozzles 41 are set towards the circuit board 9.

[0074] In application, multiple first-tapered nozzles 41 are distributed vertically, which can form a multi-layered jet flow field from top to bottom on the surface of the circuit board 9. The cone angle coverage of each nozzle jet overlaps with each other, forming a continuous and uniform annular lateral scouring effect. This arrangement can not only enhance the liquid flow rate at the orifice and middle section of the blind hole, but also form a stable shear force field, which helps to remove bubbles and electrolytic byproducts inside the hole, thereby keeping the inside of the blind hole in an active electrolytic state and promoting the uniform deposition of silver ions on the hole wall.

[0075] Regarding the specific jet structure of the aforementioned bottom nozzle 5, this embodiment is, for example... Figure 1 and Figure 4As shown, the bottom nozzle 5 has multiple 30-degree second tapered nozzles 51 arranged sequentially along its length, with the second tapered nozzles 51 facing the circuit board 9.

[0076] The bottom spray pipe 5 is equipped with four second tapered nozzles 51, which are arranged at an angle of 65 degrees, 55 degrees, 45 degrees and 35 degrees upward along the side wall of the electrolytic cell to the side of the circuit board 9, and the ends of the four second tapered nozzles 51 are on the same inclined plane.

[0077] When applied, the bottom nozzle 5 forms a composite upward flow by spraying in a multi-angle layered manner, which can generate upward disturbance at the bottom of the electroplating tank 1, so that the electrolyte is evenly distributed in the blind hole area at the bottom of the tank; the superposition of the flow velocities of nozzles at different angles accelerates the liquid renewal rate at the bottom of the blind hole, significantly reduces the dead angle of deposition at the bottom of the hole, so that the thickness of the silver layer at the bottom of the hole is consistent with the hole wall, and the overall coating is more dense; the jet flow of the bottom nozzle 5 and the horizontal jet flow formed by the side nozzle 4 are superimposed to each other to construct a three-dimensional disturbance flow field, which enhances the uniformity of ion migration in the hole.

[0078] In addition, a flow distribution chamber and a throttling orifice are added inside the bottom spray pipe 5 to keep the spray flow rate between the multiple second tapered nozzles 51 constant; the second tapered nozzles 51 adopt a quick-release interface structure for easy cleaning and maintenance.

[0079] Regarding the specific moving structure of the aforementioned movable nozzle 6, this embodiment is, for example... Figures 1 to 4 As shown, above the electrolytic cell, a linear moving module 7 is arranged along the length of the electrolytic cell; the moving slider 71 of the linear moving module 7 moves along the length of the electrolytic cell; the moving nozzle 6 is fixed on the moving slider 71, and the linear moving module 7 drives the moving nozzle 6 to move along the length of the electrolytic cell.

[0080] Among them, the linear motion module 7 drives the moving slider 71 to move along the length direction of the electrolytic cell through the transmission structure of the servo motor driving the lead screw nut.

[0081] In application, the moving nozzle 6 can periodically reciprocate under the drive of the linear module, so that the spray range covers the entire circuit board 9 area, realizing dynamic spray coverage of all blind holes; the servo motor controls the moving speed and stroke, and can adjust the rhythm according to the density or position distribution of blind holes, so that each blind hole can receive sufficient jet impact; this mechanism forms a synchronous control logic with the side nozzle 4 and the bottom nozzle 5 to achieve the matching of the spray cycle and the electroplating current waveform, further improving the density of the coating and the uniformity of the electric field distribution.

[0082] In addition, position sensors and encoders can be installed on the mobile module to achieve closed-loop control with nozzle positioning accuracy within 0.1mm; the module housing is equipped with a corrosion-resistant sealing cover to prevent plating solution from splashing in.

[0083] Regarding the specific rotating structure of the aforementioned movable nozzle 6, this embodiment is, for example... Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, a rotating unit 8 is installed on the movable slider 71. The rotating unit 8 includes a rotating base 81, a rotating motor 82, and a rotating ring 83. The rotating base 81 has a hollow cantilever extending outward from the movable slider 71. The top and bottom of the hollow cantilever are equipped with plane bearings 84, and the rotating ring 83 is sleeved between the two plane bearings 84. The inner ring of the rotating ring 83 is provided with a keyway 831. The movable nozzle 6 passes through the inner ring of the rotating ring 83 and extends into the electrolytic cell. The fixed end 61 of the movable nozzle 6 is provided with a protruding key tooth 611, which is engaged and fixed with the keyway 831. The outer ring of the rotating ring 83 is provided with a transmission tooth 832. The rotating motor 82 is installed on the rotating base 81. The output shaft of the rotating motor 82 is equipped with a transmission gear 821. The transmission gear 821 meshes with the rotating ring 83 for transmission. The rotating motor 82 drives the rotating ring 83 to drive the movable nozzle 6 to swing back and forth to the left, front, and right sides of the circuit board 9, so that the silver plating liquid is thrown out in a fan shape.

[0084] In application, the rotating unit 8 drives the moving nozzle 6 to rotate around its own axis. The keyway 831-key tooth 611 connection structure ensures stable power transmission, allowing the nozzle to form a fan-shaped spray area around the circuit board 9. This structure achieves circumferential coverage spraying of the blind hole, effectively eliminating the shadow area formed on both sides of the blind hole by traditional static nozzles. The rotating motor 82 can adjust its speed according to the flow field detection signal to keep the fan-shaped spray angle and flow rate coordinated, thereby further enhancing the uniformity of the silver layer thickness and the stability of the electric field.

[0085] In addition, anti-corrosion lubricant can be injected between the rotating ring 83 and the plane bearing 84; the rotating unit 8 can be linked with the linear motion module 7 to achieve programming control, forming a "reciprocating + rotating" composite motion trajectory.

[0086] Regarding the specific jet structure of the aforementioned movable nozzle 6, this embodiment is, for example... Figure 3 As shown, the liquid supply pipe 11 is connected to the top of the fixed end 61 of the movable nozzle 6, so that the silver plating liquid flows into the movable nozzle 6 from top to bottom; the movable nozzle 6 is provided with a plurality of 15-degree third tapered nozzles 62 from top to bottom along its own length direction, and the third tapered nozzles 62 are set towards the circuit board 9.

[0087] The movable nozzle 6 and the liquid supply pipe 11 are connected by a rotatable connector via a high-pressure pipeline.

[0088] In application, multiple sets of third-tapered nozzles 62 are arranged in a small-angle array, causing the sprayed silver plating solution to form a dense fine stream that is injected into the blind hole and forms a dynamic fan-shaped jet zone under the drive of rotation and movement. This structure ensures that the blind hole receives sufficient impact and liquid renewal in all directions, prevents concentration polarization of the electrolyte inside the hole, and thus ensures that the thickness of the silver plating layer is consistent at the hole opening, middle section, and bottom.

[0089] In addition, a micro-adjustment valve is installed at the nozzle to achieve independent flow control, so as to accommodate circuit boards 9 of different sizes and their blind holes.

[0090] In addition, a real-time detection module for current density, temperature and liquid flow rate is installed in the electrolytic cell. The real-time detection module feeds back the multi-point current feedback signal in the electrolytic cell, and dynamically adjusts the spray flow rate and spray rhythm of the side nozzle 4 and bottom nozzle 5, as well as the spray flow rate and movement rhythm of the moving nozzle 6.

[0091] The second embodiment of the PCB blind hole silver filling device differs from the first embodiment in that a control valve for controlling the spraying rhythm is installed between the first tapered nozzle 41 and the side spray pipe 4; the control valve uses wired electrical control for data exchange control.

[0092] When applied, the control valve can periodically open and close the first tapered nozzle 41 of each layer of the side nozzle 4 to form a pulse jet mode, which causes the liquid in the blind hole to produce alternating forward and reverse flow, further enhancing the fluid disturbance and ion exchange rate in the blind hole. The pulse jet and the rotating jet formed by the moving nozzle 6 can form a multi-frequency composite flow field in the hole, improve the electrolyte concentration gradient, thereby increasing the deposition rate and reducing bubble adhesion.

[0093] The control valve adopts an electromagnetic control structure, which, combined with a PLC or servo control system, enables synchronous adjustment of multiple nozzles.

[0094] The third embodiment of the PCB blind hole silver filling device differs from the first embodiment in that a regulating valve is provided between the bottom spray pipe 5 and the liquid supply pipe 11 to control the spray rhythm and spray pressure; the regulating valve is controlled by wired electrical control for data exchange.

[0095] In application, the periodic disturbance of the flow field at the bottom of the electroplating tank 1 is achieved by adjusting the valve to control the spray pressure and frequency in real time, preventing silver ions from depositing at the bottom of the tank or causing flow stagnation at the bottom of the blind holes; combined with the upper flow control of the side spray and the moving nozzle 6, a fluid circulation channel from bottom to top can be formed to achieve the overall renewal of the electrolyte; this measure effectively improves the electric field density at the bottom of the hole and the adhesion strength of the silver layer.

[0096] The regulating valve, combined with a pressure sensor, forms a closed-loop control system with a PLC or servo control system; the three-stage dynamic mode of "pre-rinse - electrodeposition - stability compensation" can be achieved by adjusting the spray pressure at different stages of electroplating.

[0097] Based on the above embodiments of the PCB blind via silver filling device, a method for filling PCB blind vias with silver is provided, such as... Figure 6 As shown, the steps are executed sequentially from S1 to S6.

[0098] S1. Workpiece preparation: After pre-cleaning and surface activation treatment, the circuit board is installed between the positioning base and the positioning hanger in the electroplating tank.

[0099] S2. Liquid circulation and spray initialization: Turn on the liquid supply of the electroplating tank so that the silver plating solution is supplied from the side spray pipe, bottom spray pipe and moving spray pipe simultaneously and sprayed to establish a stable liquid circulation channel.

[0100] Among them, the bottom spray pipe is controlled to spray silver plating liquid from bottom to top at a preset intermittent rhythm and adjustable spray pressure, which is used to disturb the liquid flow field at the bottom of the electroplating tank and promote the liquid renewal inside the blind holes of the circuit board.

[0101] S3, Multi-angle side spray uniform distribution stage: Control the first tapered nozzle in the side spray pipe to spray in layers from top to bottom, so that the silver plating liquid covers the side wall of the blind hole and the hole area of ​​the circuit board with different incident angles, forming a stable circulation distribution; so that by adjusting the spray rhythm and flow rate ratio, the current density in the hole area is evenly distributed, avoiding over-plating or under-plating.

[0102] S4, Dynamic Movement and Rotation Silver Spraying Stage: The linear movement module and rotation unit are activated to drive the moving nozzle to move along the length of the electroplating tank and rotate around its own axis at a controllable speed.

[0103] During the reciprocating motion of the moving nozzle, the third tapered nozzle ejects the silver plating liquid at a spray angle of approximately 15°. In conjunction with the rotation of the moving nozzle, the third tapered nozzle is distributed in a fan shape to cover the surface of the circuit board and enter the circumferential inner wall and bottom of the blind hole, realizing the full-space dynamic renewal of the liquid inside the blind hole.

[0104] Among them, by adjusting the reciprocating frequency and rotational angular velocity of the moving nozzle, and periodically strengthening the silver spraying of blind holes in different areas, the uniformity of the silver layer thickness in the holes can be improved.

[0105] S5. Synchronous Electroplating Control Stage: During the silver spraying process, in conjunction with the real-time detection modules for current density, temperature and liquid flow rate installed in the electroplating tank, the spray flow rate and spray rhythm of the side spray pipe and bottom spray pipe, as well as the spray flow rate and movement rhythm of the moving spray pipe, are dynamically adjusted based on the multi-point current feedback signals in the electrolytic tank.

[0106] When the deviation of the blind hole current density exceeds the set threshold, the moving nozzle automatically optimizes the injection pressure and rotation angle to maintain the balance of silver ion concentration in the hole.

[0107] S6. Post-processing and quality inspection: After stopping the liquid supply, take out the silver-plated circuit board and rinse, dry and test the thickness of the silver layer in the hole in sequence to ensure that the density and uniformity of the silver layer on the inner wall and bottom of the blind hole of the circuit board meet the preset standards.

[0108] When applying this invention to fill silver in blind holes on PCBs, steps S1 to S6 are not performed in isolation, but rather form a collaborative control link of "precise positioning - multi-directional flow field establishment - dynamic jet control - electric field closed-loop correction - plating verification". Its key role is to achieve high consistency and high density of silver deposition in blind holes through spatial composite fluid disturbance and real-time feedback control.

[0109] During the execution process, the workpiece preparation stage of step S1 uses precise clamping between the positioning hanger and the positioning base to keep the circuit board in a vertically suspended posture, establishing a stable reference surface for subsequent multi-directional spraying; achieving uniform distribution of jet impact force and electric field force, and preventing uneven local deposition thickness caused by angular deviation.

[0110] In the liquid circulation and jet initialization stage of step S2, the bottom spray pipe adopts a layered structure with multi-angle tapered nozzles (65° to 35°) to spray the silver plating solution in an intermittent pulse manner. This creates an upward vortex flow field at the bottom of the tank, which overlaps with the horizontal flow formed by the side spray, thereby achieving full-space disturbance of the fluid within the tank. This not only enhances the electrolyte renewal rate at the bottom of the blind holes but also reduces bubble retention and deposition dead zones within the holes, which is a key foundation for achieving uniform film formation.

[0111] In the multi-angle side spray uniform distribution stage of step S3, the 60° tapered nozzle sprays silver plating liquid in an upper and lower layer sequence, forming a radial flow field around the surface of the circuit board. This forms a composite circulation with the upward flow in step S2, achieving continuous scouring of the orifice and the middle section of the orifice. By adjusting the spray rhythm and flow rate ratio, the system can dynamically balance the current density of different orifice positions, making the potential distribution in the blind orifice tend to be uniform, thereby effectively suppressing electrode polarization and reducing local over-plating or under-plating.

[0112] In the dynamic movement and rotation silver spraying stage of step S4, the linear module drives the moving nozzle to move along the length of the electroplating tank, and the rotating unit drives its rotation, so that the jet flow from the third tapered nozzle forms a fan-shaped coverage. This stage realizes periodic impact and liquid replacement on each side wall and bottom of the blind hole in space. By controlling the spraying frequency and rotational angular velocity, enhanced silver spraying can be carried out for different hole areas to achieve dynamic circulation and renewal of the electrolyte in the hole. In synergy with step S3, a composite vortex flow structure is formed, so that the silver ion concentration field in the hole remains uniform at all times.

[0113] In the synchronous electroplating control stage of step S5, the real-time detection module in the electroplating tank provides feedback on current density and temperature data. The control system automatically adjusts the spray pressure and rhythm based on the feedback, achieving closed-loop control. When a deviation in current density within the hole is detected, the system instantly optimizes the spray angle and flow rate to compensate for local deposition deviations, ensuring consistent coating thickness. This stage achieves synergistic matching of spray flow control, electric field distribution, and deposition rate, which is beneficial for improving the stability of blind hole electroplating.

[0114] In the post-processing and quality inspection stage of step S6, the process effect is verified by in-hole thickness detection and surface finish analysis. Thanks to the aforementioned flow field optimization and electric field control mechanism, the thickness difference of the silver layer inside the hole can be controlled within ±3%, which is significantly better than traditional vibration or static electroplating processes. Moreover, the hole walls are smooth, there are no voids at the bottom of the hole, and the adhesion is strong, meeting the conductivity and soldering requirements of high-density interconnect boards.

[0115] In addition, during steps S2 to S4, a pulsed current synchronous control mode is introduced. By matching the pulse period with the jet rhythm, the resonance between the ion migration rate and the jet disturbance frequency is achieved, thereby improving the deposition density.

[0116] Multi-layer process integration: This method can also be extended to blind-hole-through-hole hybrid structures or multi-layer composite plate electroplating scenarios. By controlling the spray direction and rhythm of different nozzles, zoned silver plating and synchronous homogenization control can be achieved.

[0117] In summary, this method fundamentally solves the problems of restricted electrolyte flow and uneven silver deposition inside blind holes by using multi-nozzle collaborative flow field control and closed-loop feedback adjustment mechanism. It achieves synchronous coupling optimization of flow field, temperature field and electric field, and has significant industrial application and manufacturing adaptability.

[0118] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A device for filling blind vias with silver in a PCB board, characterized in that, The system includes an electroplating tank, a positioning base, a positioning hanger, side spray pipes, a bottom spray pipe, and a movable spray pipe. The positioning base is located at the bottom centerline of the electroplating tank, and the positioning hanger is detachably located at the top centerline of the electroplating tank. The positioning base is used to position and hold the bottom of the circuit board to be silver-plated, and the positioning hanger is used to position and hold the top of the circuit board. The side spray pipes are arranged vertically along the depth direction of the electroplating tank, and multiple side spray pipes are arranged along the length direction of the electroplating tank, spraying silver plating liquid towards the side of the circuit board. The bottom spray pipe is parallel to the transverse direction of the electroplating tank and is arranged at the bottom centerline of the circuit board. The bottom of the electroplating tank is equipped with multiple side spray nozzles arranged along its length. The bottom spray nozzles spray silver plating solution at a controlled rhythm towards the side of the circuit board, increasing the agitation of the liquid within the tank. A movable spray nozzle is suspended within the electroplating tank and moves along its length, rotating around its own axis at a controlled speed to throw the silver plating solution onto the side of the circuit board and into blind holes. The movable spray nozzle is positioned between the circuit board and the side spray nozzles. The movable spray nozzle, along with the multiple side spray nozzles and the bottom spray nozzle, is connected to the supply pipe of the electroplating tank to receive the silver plating solution. The bottom of the circuit board is inserted into the positioning base as the positioning bracket is installed on the electroplating tank, thus fixing the circuit board in the electroplating tank; Above the electroplating tank, a linear moving module is provided, which is arranged along the length of the electroplating tank. The linear motion module's slider moves along the length of the electroplating tank; the moving nozzle is fixed on the slider, and the linear motion module drives the moving nozzle to move along the length of the electroplating tank. A rotating unit is mounted on the movable slider. The rotating unit includes a rotating base, a rotating motor, and a rotating ring. A hollow cantilever extends outward from the movable slider from the rotating base. Planar bearings are installed at the top and bottom of the hollow cantilever, and the rotating ring is sleeved between the two planar bearings. The inner ring of the rotating ring has a keyway. The movable nozzle passes through the inner ring of the rotating ring and extends into the electroplating tank. The fixed end of the movable nozzle has protruding key teeth that are locked to the keyway. The outer ring of the rotating ring has transmission teeth. The rotating motor is mounted on the rotating base. A transmission gear is mounted on the output shaft of the rotating motor. The transmission gear meshes with the rotating ring, and the rotating motor drives the rotating ring to move the movable nozzle back and forth to the left, front, and right sides of the circuit board, causing the silver plating solution to be thrown out in a fan shape. The liquid supply pipe is connected to the top of the fixed end of the movable nozzle, so that the silver plating liquid flows into the movable nozzle from top to bottom; the movable nozzle is provided with a plurality of 15-degree third tapered nozzles from top to bottom along its own length direction, and the third tapered nozzles are set towards the circuit board.

2. The PCB blind via silver filling device according to claim 1, characterized in that, The side spray pipe is provided with a plurality of 60-degree first tapered nozzles in the electroplating tank from top to bottom along the length direction, and the first tapered nozzles are arranged facing the circuit board.

3. The PCB board blind via silver filling device according to claim 2, characterized in that, A control valve for controlling the spray rhythm is installed between the first tapered nozzle and the side spray pipe.

4. The PCB board blind via silver filling device according to claim 1, characterized in that, The bottom spray pipe is arranged with a plurality of second tapered nozzles of 30 degrees along its length, and the second tapered nozzles are positioned toward the circuit board.

5. The PCB board blind via silver filling device according to claim 4, characterized in that, The bottom spray pipe is equipped with four second tapered nozzles, which are arranged at an angle of 65 degrees, 55 degrees, 45 degrees and 35 degrees upward along the side wall of the electroplating tank to the side of the circuit board, and the ends of the four second tapered nozzles are on the same inclined plane.

6. A method for filling blind vias with silver in a PCB board, comprising the PCB board blind via silver filling device according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Workpiece Preparation: After pre-cleaning and surface activation treatment, the circuit board is installed between the positioning base and the positioning hanger of the electroplating tank; S2. Liquid Circulation and Spray Initialization: Turn on the liquid supply of the electroplating tank, so that the silver plating liquid is supplied from the side spray pipe, bottom spray pipe and moving spray pipe simultaneously and spraying is started; S3. Multi-Angle Side Spray Distribution Stage: Control the first tapered nozzle in the side spray pipe to spray in layers from top to bottom, so that the silver plating liquid covers the blind hole sidewall and hole area of ​​the circuit board with different incident angles, forming a stable circulation distribution; S4. Dynamic Movement and Rotation Silver Spraying Stage: The linear movement module and rotation unit are activated to drive the moving nozzle to move along the length of the electroplating tank and rotate around its own axis at a controllable speed. By adjusting the reciprocating frequency and rotational angular velocity of the moving nozzle, periodic enhanced silver spraying is performed on blind holes in different areas. S5. Synchronous Electroplating Control Stage: During the silver spraying process, in conjunction with the real-time detection modules for current density, temperature, and liquid flow rate installed in the electroplating tank, the spray flow rate and spray rhythm of the side nozzles and bottom nozzles, as well as the spray flow rate and movement rhythm of the moving nozzle, are dynamically adjusted based on the multi-point current feedback signals in the electroplating tank. When the current density deviation of the blind hole is detected to exceed the set threshold, the moving nozzle automatically optimizes the spray pressure and rotation angle. S6. Post-processing and Quality Inspection: After the liquid supply is stopped, the silver-plated circuit board is removed and rinsed, dried, and the thickness of the silver layer in the hole is inspected in sequence.

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