An extrusion plug device for filling through holes of a circuit board

Abstract

This invention relates to the field of circuit board manufacturing technology, specifically to a compression-type via-filling device for circuit board vias. The device includes a frame, an upper clamping frame, a lower clamping frame, a scraper assembly, and a vacuum roller. The upper and lower clamping frames are used to clamp the upper and lower ends of the circuit board, respectively, and drive the circuit board to feed vertically. The scraper assembly includes multiple sub-blades, each with an independent degree of freedom to move towards or away from the circuit board surface. The scraper assembly has a fluid equalization chamber filled with incompressible fluid, and a flexible sealing membrane inside the fluid equalization chamber abuts against the sub-blades. The vacuum roller is arranged opposite to the scraper assembly. This invention establishes a flat reference through vertical stretching of the upper and lower clamping frames, combines this with the fluid equalization chamber to ensure the sub-blades are pressed against the board surface with equal pressure, and utilizes the back vacuum roller for two-stage negative pressure suction. This achieves uniform force distribution in the working area and eliminates air bubbles within the vias, improving the micro-via filling density and yield rate.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to a compression-type hole-filling device for filling through holes in circuit boards. Background Technology

[0002] In intelligent integrated circuit and advanced packaging manufacturing processes, extrusion-type via-filling devices for circuit board vias are mainly used to fill specific resin paste into the vias. In existing technologies, such devices typically employ servo-driven scraper assemblies or downward-pressing extrusion heads, combined with a bottom support base design, to generate extrusion pressure at the resin-substrate interface through mechanical transmission, overcoming the resistance within the via to complete directional instillation.

[0003] However, the aforementioned technologies face conventional challenges in substrate fixation and support during practical applications. During the via plugging process, the equipment needs to apply vertical extrusion pressure to the board surface to drive the resin into the holes. To prevent macroscopic displacement of the board under stress, existing equipment typically employs side clamping mechanisms or vacuum adsorption platforms for positioning and fixation. For example, existing solutions often limit the boundary displacement of the substrate by setting side pressure clamps or edge clamping structures. However, such substrate support structures are mainly used to limit horizontal sliding of the board, and their effect on improving the overall rigidity of the board and resisting vertical deformation is relatively limited.

[0004] Specifically, when the equipment is used in the processing of ultra-thin PCB core boards with a thickness of less than 0.5mm, the aforementioned structures relying solely on edge clamping or uniform vacuum adsorption cannot effectively suppress local deformation of the board. Under these conditions, ultra-thin PCB substrates with a thickness of less than 0.5mm will experience local bending and warping under the combined action of the scraper's extrusion pressure and the edge clamping force. This causes changes in the contact gap between the scraper and the board surface, resulting in uneven distribution of resin extrusion pressure across different areas of the board. Specifically, in concave areas of the board surface, insufficient contact between the scraper and the board surface makes it difficult for resin to be pressed into the holes; in convex areas of the board surface, excessive scraper pressure can easily scrape away resin at the hole openings or damage the copper surface, thus affecting the density and yield of the micropore filling of the ultra-thin substrate.

[0005] To address the problem of uneven resin extrusion pressure distribution caused by localized changes in the contact gap between the scraper and the board surface, an extrusion-type plugging device for filling circuit board vias is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a compression-type hole-filling device for filling through holes in circuit boards, which solves the problem of uneven resin pressure caused by deformation under force when filling holes in ultra-thin circuit boards. By vertically stretching the upper and lower clamping frames to establish a flat reference, and combining the fluid equalization chamber to make the sub-blade press against the board surface with equal pressure, and using the back vacuum roller for two-stage negative pressure suction, the device achieves uniform force in the working area and eliminates air bubbles in the holes, thereby improving the density of micropore filling and yield.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A compression-type hole-filling device for filling through-holes in a circuit board includes a frame, an upper clamping frame, and a lower clamping frame. The upper and lower clamping frames are used to clamp the upper and lower ends of the circuit board, respectively, and drive the circuit board to feed vertically, applying a pre-tension force to the circuit board during feeding. Existing technologies typically place the circuit board horizontally, and thin boards are prone to deformation under their own weight and the pressure of the scraper. This device vertically stretches the circuit board through the upper and lower clamping frames, using tension force to counteract board deformation and providing a flat motion reference surface for the scraper operation.

[0008] It also includes a scraper assembly disposed on one side of the circuit board. The scraper assembly includes multiple sub-blades arranged along the width of the circuit board, each of which has an independent degree of freedom to move towards or away from the circuit board surface. The scraper assembly has a fluid equalization chamber filled with incompressible fluid inside. A flexible sealing membrane inside the fluid equalization chamber abuts against the sub-blades, using Pascal's principle to provide a constant compressive back force to the sub-blades. Existing integral scrapers cannot conform to the local undulations of the board surface, resulting in resin leakage in some areas and scratching of the copper foil in others. This device divides the scraper into multiple sub-blades. With the action of the fluid equalization chamber, because the pressure of the sealed fluid is equal everywhere, each sub-blade can independently extend and retract according to the height of the board surface. Regardless of the extent of extension or retraction, the force pressing on the board surface remains consistent, ensuring uniform filling pressure across the entire board.

[0009] On the other side of the circuit board, a vacuum roller is arranged opposite to the scraper assembly. This vacuum roller provides rigid support to the back of the circuit board while simultaneously using negative pressure suction to press resin into the through-holes in conjunction with the sub-blade. Existing technologies mostly rely solely on the front scraper to force resin into the holes, which can lead to air trapped inside and voids. This device features vacuum rollers on both the front and back of the extrusion surface. The front side pushes resin in with the blade, while the back side simultaneously removes air from the holes using negative pressure. This combined pushing and suction allows the resin to fill even the smallest and deepest through-holes.

[0010] Preferably, multiple sub-blades are combined to form a concave integral cutting edge, with the sub-blades at the edges arranged at an angle upwards. The concave structure of the integral cutting edge allows the scraper to gather the flowing resin paste towards the center of the circuit board during operation, preventing resin from overflowing and dripping from the left and right edges of the circuit board, reducing material waste and keeping the inside of the machine clean. The upward-angled arrangement of the sub-blades at the edges provides an inward guiding force to the resin at the edges as the circuit board moves vertically downwards, further maintaining the stability of the resin accumulation and preventing the resin from slipping off the sides due to gravity.

[0011] Preferably, each of the sub-blades has a wedge-shaped cutting edge at its front end facing the circuit board feed direction, forming a cavity that gradually narrows from top to bottom between the wedge-shaped cutting edge and the circuit board surface. When the circuit board moves downward, the gradually narrowing cavity will exert spatial compression on the resin inside, and by utilizing the property of fluid compression, a high local pressure will be generated instantaneously at the cutting edge, forcibly squeezing the resin into the hole. The inclined wedge-shaped surface provides a supporting slope for the resin paste, guiding the resin paste gathered above the blade to continuously roll on its surface, rather than sliding down directly due to gravity like when encountering a right-angle wall, ensuring that there is always a sufficient source of resin in front of the hole.

[0012] Preferably, the scraper assembly includes a base with an internal fluid equalization chamber, and a slide rail for accommodating sub-blades is provided within the base. The slide rail connects to the fluid equalization chamber, and the flexible sealing membrane extends from the fluid equalization chamber to the slide rail. Integrating the fluid equalization chamber directly into the base that supports the sub-blades eliminates the need for external hydraulic cylinders and fluid delivery lines, reducing the overall space occupied by the equipment and eliminating the risk of fluid leakage due to aging of pipe joints. The slide rail within the base provides clear mechanical guidance for the independent extension and retraction of each sub-blade, preventing the blades from tilting or misaligning during compression and friction. The flexible sealing membrane extending into the slide rail ensures that the thrust of the fluid acts directly and accurately on the tail of the sub-blade.

[0013] Preferably, the sub-blade has a guide hole fitted onto the base, and an elastic compensation component is provided between the sub-blade and the base. In the non-operating state, the elastic compensation component pushes the extruded ends of each sub-blade to a uniform initial reference plane. When the equipment is stopped or the circuit board is replaced, the pressure in the fluid equalization chamber is released, and the elastic compensation component can actively push all the sub-blades that were previously of uneven length due to the undulation of the board surface back to the same horizontal line, which facilitates the staff to clean the blade edges and maintain the equipment. At the initial moment when a new circuit board enters the working area, since all the sub-blades are kept on the same plane, the blade edges will contact the board surface at the same time, preventing individual excessively long blades from getting stuck on the edge of the circuit board at the moment of startup and causing the board to tear.

[0014] Preferably, the center line of the rotating shaft of the vacuum roller and the cutting edge of the sub-blade on the opposite side are on the same horizontal projection axis; when the sub-blade squeezes the resin on the front, it will generate a vertical thrust on the circuit board, aligning the solid axis of the vacuum roller with the cutting edge, so that the thrust on the front is directly borne by the solid axis on the back, preventing the circuit board from bending when the front and rear force points are inconsistent; and at the same moment when the through hole moves to the moment when the cutting edge of the sub-blade is filled with resin, the hole just crosses the area with the greatest suction on the center line of the vacuum roller, ensuring that the front pushing and the back vacuuming actions are not delayed in time, and the docking is more precise.

[0015] Preferably, the vacuum roller includes an outer roller and a built-in negative pressure shroud. The negative pressure shroud is fixedly mounted on the frame, and the negative pressure shroud has an air guide port only on the side facing the sub-blade. The circumference of the roller is densely covered with through negative pressure micropores. The internally fixed negative pressure shroud limits the air extraction range, ensuring that the vacuum suction is concentrated only in the small area where the roller is in contact with the circuit board, preventing the vacuum pump from ineffectively extracting air from the air surface that is not in contact with the circuit board, and maintaining the negative pressure intensity of the working area. The negative pressure micropores densely distributed on the outer roller alternately pass through the internal air guide port as the roller rotates, so that as the circuit board moves downward, there are always newly rotated micropores aligned with the through holes on the back of the circuit board for continuous and uninterrupted suction.

[0016] Preferably, the roller is rotatably connected to the outer periphery of the negative pressure cover; the outer roller can rotate directly on the outer periphery by the friction force generated by the movement of the circuit board, so that there is no relative sliding between the roller surface and the circuit board surface, avoiding the scratching of the fine copper foil lines on the back of the circuit board by sliding friction; and compared with the overall rotation of the vacuum roller, the independent rotation of the roller reduces its own inertia, thereby reducing the energy consumed by its own movement and stopping, so as to avoid wear on the circuit board surface during contact.

[0017] Preferably, the outer circumference of the roller is densely covered with protrusions surrounded by negative pressure micropores. The top surfaces of the protrusions form discrete point contact supports with the back of the circuit board; the back of the circuit board only contacts the tips of the protrusions, significantly reducing the actual contact area. If the resin on the front is vacuumed through to the back, the resin will only fall into the gaps between the protrusions, rather than sticking the circuit board to the roller over a large area; and the protrusion structure slightly supports the circuit board, leaving tiny airflow channels between the roller and the circuit board. Even if the through-hole is not perfectly aligned with a negative pressure micropore, air can still flow laterally into nearby micropores through these channels, ensuring that the pumping effect is uninterrupted.

[0018] Preferably, the negative pressure shroud is internally divided into a pre-evacuation chamber and a filling chamber. The air inlet of the pre-evacuation chamber is located above the air inlet of the filling chamber, and the air pressure inside the pre-evacuation chamber is higher than that inside the filling chamber. When the through hole moves downward with the circuit board, it first passes through the upper pre-evacuation chamber. The pre-evacuation chamber has a smaller suction force (relatively higher air pressure), which can gently guide the viscous resin into the hole first, preventing the initial suction force from being too strong and directly drawing the resin through and spraying it into the machine. After the resin has entered the hole, the through hole continues to move downward into the lower filling chamber. The filling chamber has a strong suction force (high vacuum degree), which uses the strong suction force to completely remove the small air bubbles remaining at the bottom of the hole, allowing the resin to tightly fill the entire hole wall.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention applies vertical pre-tension force to the circuit board through the upper and lower clamping frames, combined with the independent telescopic structure of multiple sub-blades and fluid equalization chamber in the scraper assembly, and the negative pressure adsorption and collinear support structure of the vacuum roller on the back, forming a mechanical support and dynamic pressure compensation system on both sides. This system can maintain the flatness of the macroscopic board surface during the board feeding process and make the scraper blade automatically adapt to the local undulations of the board surface, thereby ensuring the uniform distribution of resin extrusion pressure and improving the density and yield of micropore filling of ultra-thin substrates.

[0020] 2. This invention utilizes the vertical stretching action of the upper and lower clamping frames to provide a flat motion reference surface for the circuit board, limiting large-area concave-convex deformation of the board material under pressure. Simultaneously, the scraper assembly divides the overall blade into multiple sub-blades. Utilizing the physical property that the fluid pressure is equal throughout the fluid equalization chamber, a consistent compressive back force is provided to each sub-blade sliding within the slide rail. When there are thickness tolerances or localized micro-undulations on the circuit board surface, each sub-blade can independently compensate for expansion and contraction and conform to the board surface. Further localized pressure adjustment is performed on the overall flattened board surface, preventing adhesive leakage in concave areas or scratching of the copper surface in convex areas, thus ensuring consistent stress across the entire working area cross-section.

[0021] 3. In this invention, the center line of the vacuum roller shaft and the cutting edge of the opposing sub-blade are on the same horizontal projection line, so that the pushing force of the front sub-blade pressing the resin is directly borne by the solid shaft on the back, preventing the circuit board from bending when the front and rear force points are inconsistent; and while the resin is squeezed into the through hole by the wedge-shaped cutting edge of the sub-blade, the vacuum roller simultaneously sucks the air in the hole through the negative pressure micro-hole on the roller, forming a push-and-suction physical action to guide the resin into the through hole; and the pre-extraction chamber and filling chamber separated in the vacuum chamber can apply different suction forces in sequence as the circuit board moves downward. First, a smaller suction force (pre-extraction chamber) guides the resin into the hole, and then a larger suction force (filling chamber) extracts the residual air bubbles at the bottom of the hole. This not only avoids a single large suction force directly drawing out the resin that has not fully entered the hole and spraying it into the equipment, but also ensures the tightness of the filling and reduces the maintenance and cleaning needs of the equipment due to resin leakage. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall isometric structure of the present invention; Figure 2 This is a schematic diagram of the overall main structure of the present invention; Figure 3 This is a schematic diagram of the overall installation of the present invention; Figure 4 For the present invention Figure 3 Enlarged diagram of part A in the middle; Figure 5 This is a schematic diagram of the sub-blade assembly method of the present invention. Figure 6 This is a schematic diagram of the internal cross-sectional structure of the vacuum roller of the present invention; Figure 7 For the present invention Figure 6 Enlarged diagram of section B; Figure 8 This is a schematic diagram of the vacuum roller structure from the front view in half section. Figure 9 For the present invention Figure 8 Enlarged diagram of section C; Figure 10 This is a schematic diagram of the sliding frame in the downward state of the present invention.

[0023] In the diagram: 1. Frame; 11. Fixed frame; 12. Sliding frame; 2. Upper clamping frame; 3. Lower clamping frame; 4. Scraper assembly; 41. Sub-blade; 411. Wedge-shaped cutting edge; 412. Guide hole; 413. Elastic compensation component; 42. Fluid equalization chamber; 421. Flexible sealing membrane; 43. Base; 431. Slide rail; 5. Vacuum roller; 51. Roller; 511. Negative pressure micropore; 512. Protrusion; 52. Negative pressure cover; 521. Air inlet; 522. Pre-extraction chamber; 523. Filling chamber; 524. Partition. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figures 1 to 10 This invention provides a compression-type plugging device for filling through holes in a circuit board, the technical solution of which is as follows: A compression-type via-filling device for filling through-holes in a circuit board includes a frame 1, an upper clamping frame 2, and a lower clamping frame 3. The upper clamping frame 2 and the lower clamping frame 3 are respectively used to clamp the upper and lower ends of the circuit board and drive the circuit board to feed vertically, so as to apply a pre-tension force to the circuit board during the feeding process; see reference. Figure 1 and Figure 10 The frame 1 includes a fixed frame 11 and a sliding frame 12. The sliding frame 12 slides vertically on the fixed frame 11. The upper clamping frame 2 slides vertically on the sliding frame 12 to adjust the height of the clamped circuit board. The upper clamping frame 2 and the lower clamping frame 3 slide on the sliding frame 12 along the width direction to adjust the thickness of the clamped circuit board. To ensure the straightness of the ultra-thin circuit board (especially flexible or rigid-flex boards with a thickness in the range of 0.1mm to 0.5mm) during vertical feeding, a high-precision linear guide and a ball screw module driven by a servo motor are preferably configured between the fixed frame 11 and the sliding frame 12. Through a closed-loop control system, the servo motor can control the descent rate of the sliding frame 12. The inner sides of the clamping ends of the upper clamping frame 2 and the lower clamping frame 3 can be provided with flexible anti-slip pads to provide sufficient friction to maintain the pre-tension state and reduce the risk of local indentation on the conductive patterns at the edge of the circuit board. The anti-slip pad can be made of an elastic material with appropriate hardness according to the material and thickness of the circuit board, and is used in conjunction with the clamping drive mechanism to apply and maintain a predetermined tension before operation.

[0026] The extrusion-type plugging device also includes a scraper assembly 4 disposed on one side of the circuit board. The scraper assembly 4 includes multiple sub-blades 41 arranged along the width of the circuit board, each of which has an independent degree of freedom to move towards or away from the circuit board surface. The scraper assembly 4 has a fluid equalization chamber 42 filled with incompressible fluid inside. A flexible sealing membrane 421 inside the fluid equalization chamber 42 abuts against the sub-blades 41 to provide a constant extrusion back force to the sub-blades 41 using Pascal's principle. The incompressible fluid is preferably hydraulic oil or dimethyl silicone oil with relatively stable kinematic viscosity to ensure the immediacy and uniformity of pressure transmission. The flexible sealing membrane 421 is made of aging-resistant and fatigue-resistant fluororubber or nitrile rubber, and its edges are tightly pressed against the opening of the fluid equalization chamber 42 by a flange plate to achieve a static seal. A small gap of 0.05mm to 0.1mm is maintained between adjacent sub-blades 41, supplemented by molybdenum disulfide dry film lubrication to prevent jamming when they slide against each other; a vacuum roller 5 is provided on the other side of the circuit board, which is opposite to the scraper assembly 4. The vacuum roller 5 is used to provide rigid support on the back of the circuit board while using negative pressure adsorption force to work with the sub-blades 41 to press the resin into the through hole.

[0027] As one embodiment of the present invention, refer to Figure 1 and Figure 2 The center line of the rotating shaft of the vacuum roller 5 and the cutting edge of the sub-blade 41 on the opposite side are on the same horizontal projection axis. Ensuring that the center line of the rotating shaft of the vacuum roller 5 and the cutting edge of the sub-blade 41 are strictly collinear is a key prerequisite for improving the filling quality during the actual assembly and debugging of the engineering equipment. To achieve this high-precision mechanical alignment, the mounting base 43 of the scraper assembly 4 can be equipped with a fine-tuning slide driven by a micrometer-level micrometer screw. Before leaving the factory, operators can use a laser alignment instrument or a high-magnification industrial camera for auxiliary calibration, so that the normal deviation between the two on the horizontal projection plane is strictly controlled within 0.02 mm.

[0028] The design of having the front blade application point, the middle circuit board bearing surface, and the back vacuum roller 5 support axis aligned on the same straight line creates a static stress balance system. When the scraper assembly 4 extrudes high-viscosity resin paste onto the circuit board surface, it inevitably generates a huge normal thrust perpendicular to the board surface and inward. The slight vertical offset of the back support point will generate a turning moment in a local area of ​​the circuit board, causing the circuit board to bend microscopically. This embodiment, through its collinear design, ensures that all the extrusion stress generated on the front is directly transmitted to the back vacuum roller 5, thereby eliminating the conditions for the generation of the turning moment, improving the normal stiffness of the circuit board in the linear working area, and ensuring that the filling pressure stress on the front can be converted into kinetic energy that pushes the resin into the through hole without loss.

[0029] As one embodiment of the present invention, refer to Figure 3 and Figure 4 The scraper assembly 4 includes a base 43 with an internal fluid equalization chamber 42. The base 43 has a slide 431 for accommodating the sub-blade 41. The slide 431 is connected to the fluid equalization chamber 42. The flexible sealing membrane 421 extends from the fluid equalization chamber 42 to the slide 431. To meet the requirements of structural strength and extremely high reliability of fluid sealing of the equipment under high-frequency operation, the base 43 is preferably made of high-strength aerospace-grade aluminum alloy (such as 7075-T6) or stainless steel and integrally machined by a five-axis CNC machine tool to avoid stress concentration and fluid leakage risks caused by splicing multiple parts. The inner wall of the slide 431 inside the base 43 needs to be subjected to high-frequency quenching and precision grinding and polishing. Its surface roughness Ra value is strictly controlled below 0.4 micrometers. The fit clearance between the sub-blade 41 and the slide 431 is controlled within the micro-sliding fit range of 0.01 mm to 0.03 mm. This can ensure extremely low damping and smooth sliding of the sub-blade 41, and effectively prevent any slight left and right swaying or jamming when it is under pressure.

[0030] The incompressible fluid filling the fluid equalization chamber 42 is preferably a special dimethyl silicone oil with stable kinematic viscosity and an extremely low coefficient of thermal expansion, or a high-quality aviation hydraulic oil, to ensure the steady state of the internal fluid volume and hydraulic conduction characteristics under long-term continuous high-intensity operation and equipment heating conditions. A more crucial sealing design is that the flexible sealing membrane 421 (often made of corrosion-resistant, high-frequency fatigue-resistant nitrile rubber composite layer or fluororubber material) extends directly from the wide main cavity of the fluid equalization chamber 42, seamlessly covering the ends of each narrow slide 431, forming a thrust buffer surface similar to an array of independent hydraulic cylinders. When any sub-blade 41 is forced to retract due to the tiny copper foil protrusions 512 on the circuit board surface, the compressed fluid can perfectly follow Pascal's laws of physics, instantly and without kinetic energy attenuation, transmitting an equal amount of pressure to every corner of the sealed system, thereby pushing other sub-blades 41 in corresponding low-lying areas of the board surface forward to compensate.

[0031] As one embodiment of the present invention, refer to Figure 4The sub-blade 41 has a guide hole 412 fitted onto the base 43, and an elastic compensation member 413 is provided between the sub-blade 41 and the base 43. In the non-operating state, the elastic compensation member 413 pushes the extruded ends of each sub-blade 41 to a unified initial reference plane. The guide support component fitted onto the base 43 is usually made of tin bronze alloy with excellent self-lubricating properties or hard high-speed steel with surface composite nitriding treatment. Its precise coaxial cooperation with the guide hole 412 inside the sub-blade 41 further enhances the blade's ability to resist lateral disturbance torque when performing independent micro-extension and contraction. The elastic compensation member 413 can be a customized high fatigue life micro-cylindrical helical compression spring or a butterfly micro-spring assembly made of multiple layers of ultra-thin metal. The critical stiffness coefficient (K value) of these elastic compensators 413 must be rigorously calculated and calibrated by bench tests: the reverse preload thrust generated must be large enough to precisely overcome the sum of all static and dynamic friction forces between the sub-blade 41 and the inner wall of the slide 431, and between the sub-blade 41 and the tail flexible sealing membrane 421; but at the same time, the preload thrust must be strictly guaranteed to be much smaller than the huge positive extrusion back force exerted by the incompressible fluid in the fluid equalization chamber 42 under operating conditions.

[0032] When the equipment is in a non-operational static state, such as when it is shut down, replacing different batches of circuit boards, or actively depressurizing the fluid chamber, the elastic compensation component 413 can automatically, quickly, and smoothly push back all the sub-blades 41 that may be uneven in length due to the undulation of the board surface in the previous process, ensuring that their wedge-shaped extrusion front ends are precisely aligned again on an absolutely uniform initial horizontal reference plane. This not only makes it convenient for operators to use a lint-free cloth to efficiently clean the residual resin on the entire continuous cutting edge of the scraper in one go during shift handover maintenance, but more importantly, at the moment of initial contact when the next brand-new unprocessed circuit board enters the core working area of ​​the scraper, the absolutely flat blade array can ensure absolute lateral synchronization of the initial force, so as to avoid individual independent sub-blades 41 that are too long due to not being reset from getting stuck on the circuit board at the moment of startup.

[0033] As one embodiment of the present invention, refer to Figure 4 Each of the sub-blades 41 has a wedge-shaped cutting edge 411 at its front end facing the circuit board feeding direction. The wedge-shaped cutting edge 411 forms a cavity that gradually narrows from top to bottom with the circuit board surface. The angle between the wedge-shaped cutting edge 411 and the vertical circuit board is preferably set to 30 to 45 degrees. When the circuit board is fed downwards, this converging wedge-shaped cavity will generate intense spatial compression on the high-viscosity resin paste, producing extremely high local hydrodynamic pressure near the blade contact line, forcibly injecting the resin into the micropores. Simultaneously, the inclined surface provides a guiding slope for the resin, causing the converging paste to generate dynamic tumbling eddies under compression and friction, preventing local resin stagnation and failure or premature cross-linking and curing due to friction, ensuring the homogeneity and filling activity of the resin.

[0034] As one embodiment of the present invention, refer to Figure 5 Multiple sub-blades 41 are combined to form a concave integral cutting edge, with the sub-blades 41 at the edges arranged obliquely upwards. For clarity, the sub-blades 41 are enlarged in the accompanying drawings. In practice, the number of sub-blades 41 should be greater and their size smaller to respond more sensitively to the minute protrusions and depressions on the circuit board surface. The width of a single sub-blade 41 is typically limited to 5 to 10 millimeters, and multiple blades are spliced ​​together to form a centrally concave, three-dimensional cutting edge. The obliquely upward arrangement of the sub-blades 41 at the edges creates an inwardly converging flow field. When the circuit board is fed vertically downwards, the edge blades apply an inward converging force to the overflowing resin, continuously driving and compacting it to the central core working area, thereby preventing edge overflow and material waste, and ensuring a consistent resin supply to all through-holes on the board.

[0035] As one embodiment of the present invention, refer to Figure 1 The vacuum roller 5 includes an outer roller 51 and an inner negative pressure shroud 52. The negative pressure shroud 52 is fixedly mounted on the frame 1, and the negative pressure shroud 52 has an air guide port 521 only on the side facing the sub-blade 41. The circumference of the roller 51 is densely covered with through negative pressure micropores 511. The roller 51 is made of high-strength carbon fiber or micro-arc anodized hard aluminum alloy tube, and the surface is densely covered with negative pressure micropores 511 with a diameter of 0.5 to 1.0 mm using laser drilling technology. The negative pressure shroud 52 is welded together and is statically fixed to the frame 1 by a flange. A polytetrafluoroethylene composite sealing ring is used between the negative pressure shroud 52 and the roller 51 to ensure dynamic airtightness. The negative pressure shroud 52 has a strip-shaped air guide port 521 only on a small side facing the blade working zone, so as to accurately concentrate the suction of the vacuum pump on the contact surface where the scraper is pressing by means of directional air extraction design, avoiding air leakage in ineffective areas and maintaining a high-intensity negative pressure adsorption field in the working area.

[0036] As one embodiment of the present invention, refer to Figures 6-9 The roller 51 is rotatably connected to the outer periphery of the negative pressure cover 52. A miniature crossed roller bearing is fitted between the roller 51 and the negative pressure cover 52 to withstand the radial extrusion force transmitted by the scraper and maintain extremely low rotational resistance. The rotation of the roller 51 is passively driven by pure mechanical static friction with the back of the circuit board. When the circuit board is fed downward, its translational displacement is directly converted into rotation of the roller 51 at the same linear velocity, thereby eliminating the speed difference mismatch that may occur with independent motor drive, realizing zero relative sliding between the surface of the roller 51 and the back of the circuit board, and avoiding frictional scratches on the circuit board.

[0037] As one embodiment of the present invention, refer to Figures 6-9The outer circumference of the roller 51 is densely covered with protrusions 512 surrounded by negative pressure micropores 511. The top surfaces of the protrusions 512 form discrete point contact supports with the back of the circuit board. The matrix of protrusions 512 on the outer surface of the roller 51 is formed by chemical etching or precision micro-arc cold pressing, with the height controlled between 0.1 and 0.2 mm and the ends rounded. These protrusions 512 transform traditional surface contact into discrete point contact. On the one hand, if the resin in front accidentally breaks through the micropores and overflows, it will only fall into the tiny gaps between the protrusions 512, and will not cause the board to stick to the roller 51 over a large area and damage the board. On the other hand, the protrusions 512 slightly support the circuit board, forming a transverse micro-airflow channel network between them. Even if some of the through holes are not completely aligned with the negative pressure micropores 511, the residual air in the holes can escape smoothly through this channel network and be sucked away, ensuring that there are no dead corners in the vacuum pump.

[0038] As one embodiment of the present invention, refer to Figures 6-9 The negative pressure hood 52 is internally divided into a pre-extraction chamber 522 and a filling chamber 523. The air inlet 521 of the pre-extraction chamber 522 is located above the air inlet 521 of the filling chamber 523, and the air pressure inside the pre-extraction chamber 522 is higher than the air pressure inside the filling chamber 523. The negative pressure hood 52 is internally divided into two independent upper and lower chambers that do not cross-contaminate with each other, and each is connected to an independent servo pressure regulating valve. The upper pre-extraction chamber 522 is set at a moderate negative pressure of -20 kPa to -40 kPa. When the through hole just passes through, the gentle suction guides the high viscosity resin to initially undergo capillary penetration, breaking the surface tension of the resin and preventing the resin from being completely drawn out or ruptured and ejected due to the instantaneous large negative pressure. The through-hole continues downward into the lower filling chamber 523, which maintains a high vacuum state of -60 kPa to -90 kPa. The ultimate pressure difference is used to completely remove the microbubbles deposited at the bottom of the hole, ensuring that the resin is compact and free of voids inside the cylinder. In addition, a partition 524 is added between the air inlet 521 of the pre-extraction chamber 522 and the air inlet 521 of the filling chamber 523 in the annular gap between the roller and the negative pressure hood 52, so that the adsorption force of the negative pressure micropores 511 close to the pre-extraction chamber 522 and the filling chamber 523 has a significant difference.

[0039] Working principle: Refer to Figure 1 and Figure 10 To overcome the macroscopic flexural deformation of ultra-thin sheets during operation and establish a flat coating reference, the specific method is as follows: at the initial stage of operation, the upper and lower ends of the circuit board to be processed are fixed in the upper clamping frame 2 and the lower clamping frame 3, respectively. The servo mechanism drives the sliding frame 12 to feed downwards at a constant speed in the vertical direction on the fixed frame 11, and applies a constant pre-tension force to the circuit board through the upper and lower clamping frames 3 during the feeding process; thereby, the circuit board is completely flattened, providing a rigid vertical motion reference surface for the stable injection of resin fluid.

[0040] Reference Figure 3 , Figure 4 and Figure 5 To ensure precise flow and seamless distribution of the high-viscosity resin paste during extrusion, the specific method is as follows: when the circuit board descends with the sliding frame 12 past the front scraper assembly 4, the resin fluid converging above the scraper assembly 4 is first constrained by the overall blade shape. (Refer to...) Figure 5 The upwardly angled edge blades 41, as the circuit board moves downwards, exert an inward guiding force on the resin attempting to overflow from both sides, forcing the fluid to converge towards the central high-density working area. Subsequently, referring to... Figure 4 The wedge-shaped cutting edge 411 at the tip of the sub-blade 41 forms a gradually narrowing converging cavity with the plate surface. Within this microscopic cavity, the resin fluid is intensely compressed, instantly generating extremely high local dynamic pressure and being forcibly pushed into the guide hole. During this process, if microscopic undulations exist on the plate surface causing individual sub-blades 41 to retract under pressure, they will directly compress the fluid equalization chamber 42 within the base 43. The incompressible hydraulic fluid within the equalization chamber then passes through the flexible sealing membrane 421, instantly transmitting an equal amount of pressure to the other sub-blades 41, pushing them out of the recessed area conforming to the plate surface, thereby achieving isobaric adaptive coating of the resin paste across the entire cross-section.

[0041] Reference Figure 2 as well as Figures 6 to 9 To thoroughly remove internal air bubbles and prevent the fluid from being instantly punctured due to excessive pressure difference when the resin flows microscopically into the through-hole, a vacuum roller 5 is specifically installed on the back of the circuit board, precisely collinear with the cutting edge of the sub-blade 41. At the same instant the resin on the front is pressed into the through-hole, the hole precisely crosses the effective area of ​​the negative pressure micro-orifice 511 of the vacuum roller 5. (Refer to...) Figure 8 and Figure 9 The negative pressure shroud 52, fixed to the frame 1, is strictly divided into an upper pre-evacuation chamber 522 and a lower filling chamber 523. As the circuit board is fed downwards, the resin fluid first passes through the upper pre-evacuation chamber 522 within the through-hole, where its low suction gently guides the viscous resin to overcome the resistance of the hole wall and initially enter the hole. Next, the through-hole continues downwards into the lower filling chamber 523, where its extremely high vacuum suction completely removes stubborn micro-air bubbles that remain or have settled at the bottom of the hole, causing the resin fluid to densely fill the entire microporous channel in an oxygen-free environment.

[0042] Reference Figure 7 To prevent accidental resin overflow from sticking to the equipment, the outer roller 51 has tiny protrusions 512 on its surface that form discrete point contact supports with the back of the circuit board. A very small amount of overflowing resin will remain safely within the microscopic network of gaps between the protrusions 512. As the circuit board completes its vertical feed across the entire surface, a high-quality via-filling substrate with a dense, gapless interior and no surface adhesion is finally output, completing the entire via-filling process cycle.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A compression-type plugging device for filling through holes in a circuit board, comprising a frame, an upper clamping frame, and a lower clamping frame, characterized in that: The upper clamping frame and the lower clamping frame are used to clamp the upper and lower ends of the circuit board respectively, and drive the circuit board to feed in the vertical direction, so as to apply a pre-tension force to the circuit board during the feeding process; It also includes a scraper assembly disposed on one side of the circuit board, the scraper assembly comprising multiple sub-blades spliced ​​together along the width direction of the circuit board, each of the sub-blades having an independent degree of freedom to move closer to or away from the surface of the circuit board; The scraper assembly has a fluid equalization chamber filled with incompressible fluid inside. The flexible sealing membrane inside the fluid equalization chamber abuts against the sub-blade to provide a constant squeezing back force to the sub-blade using Pascal's principle. On the other side of the circuit board, there is a vacuum roller arranged opposite to the scraper assembly. The vacuum roller is used to provide rigid support on the back of the circuit board while using negative pressure adsorption force to work with the sub-blade to press the resin into the through hole.

2. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: Multiple sub-blades are combined to form a concave integral cutting edge, with the sub-blades at the edge arranged at an angle upwards.

3. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: Each of the sub-blades has a wedge-shaped cutting edge at its front end facing the circuit board feed direction, and a cavity that gradually narrows from top to bottom is formed between the wedge-shaped cutting edge and the circuit board surface.

4. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: The scraper assembly includes a base with an internal fluid equalization chamber, a slide for accommodating a sub-blade, the slide being connected to the fluid equalization chamber, and a flexible sealing membrane extending from the fluid equalization chamber to the slide.

5. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: The sub-blade has a guide hole fitted onto the base, and an elastic compensation component is provided between the sub-blade and the base. In the non-operating state, the elastic compensation component pushes the extrusion ends of each sub-blade to a unified initial reference plane.

6. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: The center line of the rotating shaft of the vacuum roller and the cutting edge of the sub-blade on the opposite side are on the same horizontal projection axis.

7. The extrusion-type plugging device for filling through holes in a circuit board according to claim 1, characterized in that: The vacuum roller includes an outer roller and a built-in negative pressure shroud. The negative pressure shroud is fixedly mounted on the frame, and the negative pressure shroud has an air guide port only on the side facing the sub-blade. The circumferential surface of the roller is densely covered with through negative pressure micropores.

8. The extrusion-type plugging device for filling through holes in a circuit board according to claim 7, characterized in that: The roller is rotatably connected to the outer periphery of the negative pressure cover.

9. The extrusion-type plugging device for filling through holes in a circuit board according to claim 7, characterized in that: The outer circumference of the roller is densely covered with protrusions surrounded by negative pressure micropores, and the top surface of the protrusions forms discrete point contact support with the back of the circuit board.

10. A compression-type plugging device for filling through holes in a circuit board according to claim 7, characterized in that: The negative pressure hood is internally divided into a pre-extraction chamber and a filling chamber. The air inlet of the pre-extraction chamber is located above the air inlet of the filling chamber, and the air pressure inside the pre-extraction chamber is higher than the air pressure inside the filling chamber.

Images