PCB manufacturing method and device for improving large-aperture resin plug hole

Abstract

The embodiment of the invention relates to the technical field of PCB manufacturing, in particular to a PCB manufacturing method and device for improving a large-aperture resin plug hole, and the method comprises the steps: designing an ink feeding region matched with the position of a second drilling hole when a screen printing plate is manufactured; the screen printing plate is installed on a resin hole plugging device, resin hole plugging processing is carried out on the PCB multilayer board through the resin hole plugging device, and a supporting platform is formed on the second drilled hole through the ink feeding area; feeding the PCB multilayer board subjected to the resin plug printing treatment into a baking oven for thermocuring treatment; and the PCB multilayer board is ground, and the supporting platform is removed. Through the steps, the temporary supporting platform is formed at the large-aperture drilling position and removed in subsequent grinding, the problem of uneven height caused by aperture difference is actively eliminated, the defect that resin on the edge of an orifice is sunken due to excessive removal of resin in a large-aperture area is effectively avoided, and the appearance consistency and the electrical reliability of a product are improved.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, specifically to a method and apparatus for improving PCB manufacturing with large-diameter resin-filled vias. Background Technology

[0002] In the high-end PCB manufacturing field, resin via filling is one of the key technologies for achieving high-density interconnection and ensuring product reliability. Its main function is to fill blind / buried vias or through-holes to ensure the stability of interlayer electrical connections, prevent solder ball penetration during wave soldering, and improve board surface flatness. Conventional processes involve multiple steps, including drilling, via wall pretreatment, resin filling, curing, grinding, and surface planarization. However, as electronic devices become thinner, smaller, and more integrated, this process faces increasingly prominent technical bottlenecks in practical applications.

[0003] A significant manufacturing challenge lies in the coexistence of plain vias (typically less than 0.4mm in diameter) and larger mounting holes, tool holes, or heat dissipation holes (typically 1.0mm or larger, especially 3.0mm and above) on a circuit board. Due to the substantial difference in diameter, the height of the cured resin after filling varies, easily leading to uneven grinding during subsequent polishing processes. Because the resin volume in the larger holes is greater, it preferentially contacts the grinding brush and bears more grinding force during polishing. To achieve the required overall board flatness, polishing time is often extended, which directly results in over-grinding of the resin within the larger holes, creating resin depressions at the hole edges. In severe cases, this can even lead to complete grinding through, exposing the underlying substrate or copper layer. Such defects not only affect the product's appearance but also cause a series of quality risks, including decreased electrical performance and insufficient environmental reliability.

[0004] Current industry improvements largely focus on optimizing grinding parameters, such as adjusting brush pressure and rotation speed, or adopting segmented grinding strategies. However, these methods fail to fundamentally solve the problem of resin height differences caused by pore size variations. They are passive improvements with limited effectiveness and narrow process windows. Therefore, a novel resin plugging technology that achieves breakthroughs at the structural design or process principle level is urgently needed to completely overcome the challenges of uneven grinding and resin depressions when large and small pores coexist. Summary of the Invention

[0005] In view of the above problems, embodiments of the present invention provide a PCB manufacturing method and apparatus for improving the resin-filled vias with large diameters. This is used to solve the problem that in the prior art, when there are both ordinary vias (with a diameter generally less than 0.4 mm) that need to be filled and mounting holes, tool holes, or heat dissipation holes (with a diameter generally greater than or equal to 1.0 mm, especially 3.0 mm and above) on the circuit board, the difference in the diameters of the two types of vias leads to uneven heights after the resin is filled and cured, which easily causes uneven grinding in subsequent grinding processes.

[0006] According to one aspect of the present invention, a method for manufacturing a PCB with improved large-diameter resin-filled vias is provided, the method comprising: Obtain a multilayer PCB board and drill holes in the multilayer PCB board to create a first drill hole and a second drill hole. A screen printing plate is made, and the screen printing plate has an ink application area that matches the position of the second drill hole; The screen is mounted on the resin plugging device, and the resin plugging device is used to perform resin plugging on the PCB multilayer board, and a support platform is formed on the second drill hole through the ink application area. The resin-impregnated PCB multilayer board is then placed in an oven for thermosetting. The PCB multilayer board is ground to remove the support platform.

[0007] In some alternative implementations, the diameter of the ink-dip region is smaller than the diameter of the second borehole.

[0008] In some optional embodiments, the second borehole is an irregular hole with a diameter greater than 3.0 mm, or an irregular groove with a width greater than 3.0 mm, or an irregular groove with a length greater than 3.0 mm.

[0009] In some optional embodiments, drilling is performed on the PCB multilayer board to create a first drilled hole and a second drilled hole, specifically including: The first and second holes are made by mechanical drilling and / or laser drilling.

[0010] In some alternative implementations, creating a screen print specifically includes: A stencil is fabricated based on the pad image and aperture size of the PCB multilayer board; wherein the stencil has uniform mesh holes at both the first and second drill hole positions, and an ink application area is provided in the middle of the second drill hole position; wherein the stencil is an aluminum sheet stencil.

[0011] In some optional embodiments, the PCB multilayer board is resin-filled using a resin-filling device, specifically including: Resin is scraped into the first and second drill holes through the mesh of the screen, and a support platform is formed on the second drill hole through the ink application area.

[0012] In some optional embodiments, the resin-impregnated PCB multilayer board is placed in an oven for thermosetting, specifically including: The first stage of baking was carried out on the PCB multilayer board at a baking temperature of 80°C-100°C and a baking time of 30min-60min. The PCB multilayer board was baked in the second stage at a baking temperature of 140°C-160°C and a baking time of 60min-120min. The baking temperature of the baking oven is controlled at the first temperature threshold at a cooling rate of ≤4°C / min to perform the third stage baking of the PCB multilayer board.

[0013] In some optional embodiments, the PCB multilayer board is ground to remove the support platform, specifically including: The surface of the PCB multilayer board is ground by the grinding wheel of the grinding equipment to make the surface of the first and second drilled holes consistent with the height of the PCB multilayer board surface.

[0014] In some alternative implementations, after grinding the PCB multilayer board and removing the support platform, the process further includes outer layer circuit fabrication, electroplating, solder mask treatment, surface treatment, forming treatment, and inspection treatment to generate the target PCB board.

[0015] According to one aspect of the present invention, a PCB manufacturing apparatus for improving large-diameter resin-filled vias is provided, characterized in that the apparatus is used to perform the above-described PCB manufacturing method for improving large-diameter resin-filled vias to manufacture a printed circuit board.

[0016] This invention provides a method and apparatus for improving PCB manufacturing with large-diameter resin-filled vias. The advantages of this method are as follows: During stencil fabrication, an ink application area is designed to match the location of the second drilled hole. The stencil is then mounted on a resin-filling device, which performs resin-filling treatment on the PCB multilayer board, forming a support platform on the second drilled hole through the ink application area. The resin-filled PCB multilayer board is then placed in an oven for thermosetting. Finally, the PCB multilayer board is ground to remove the support platform. Through these steps, this invention forms a temporary support platform at the location of the large-diameter drilled hole and removes it during subsequent grinding, actively eliminating the height unevenness caused by differences in hole diameter. This not only effectively avoids resin depression defects at the hole edge caused by excessive resin removal in the large-diameter area but also improves product appearance consistency and electrical reliability.

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

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic flowchart of the PCB fabrication method for improving large-diameter resin plugging vias according to Embodiment 1 of the present invention is shown. Figure 2 A flowchart illustrating step 140 of Embodiment 1 provided by the present invention is shown; Figure 3 A schematic diagram of the resin plugging process of Embodiment 1 provided by the present invention is shown.

[0019] Figure label: 31. PCB multilayer board; 32. Second drill hole; 33. Ink application area; 34. Mesh. Detailed Implementation

[0020] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0021] Example 1: Figure 1 This invention illustrates a first embodiment of the PCB manufacturing method for improving large-diameter resin-filled vias. It addresses the problem in the prior art where, when a circuit board simultaneously contains ordinary vias (with a diameter generally less than 0.4 mm) that need to be filled and larger mounting holes, tool holes, or heat dissipation holes (with a diameter generally greater than or equal to 1.0 mm, especially 3.0 mm or more), the significant difference in their diameters leads to inconsistent heights after resin filling and curing, which easily causes uneven grinding in subsequent grinding processes.

[0022] 110. Obtain a multilayer PCB board and drill holes in the multilayer PCB board to create the first and second drill holes. 120. Create a screen printing plate, and the screen printing plate has an ink application area that matches the position of the second drill hole; 130. The screen is installed on the resin plugging device, and the resin plugging device is used to perform resin plugging on the PCB multilayer board, and a support platform is formed on the second drill hole through the ink application area. 140. The resin-filled multilayer PCB board is sent into the baking oven for thermosetting. 150. Grind the PCB multilayer board to remove the support platform.

[0023] In steps 110-150, the first and second drilled holes refer to drilled holes made on the PCB multilayer board. Specifically, the second drilled hole can be a larger diameter hole, which can be achieved by mechanical drilling, for example, using drill bits of different diameters to process small and large holes respectively. Further, the ink-absorbing area refers to a specific area on the stencil that allows resin to pass through. This can be achieved by forming an ink-transparent pattern during the stencil manufacturing process using photolithography, for example, by exposing and developing a mask after coating with photosensitive emulsion. As a preferred embodiment, an opening area matching the position of the second drilled hole is set on the metal stencil using laser etching technology, mainly to control the distribution of resin at the second drilled hole position. Thus, the support platform refers to the resin protrusion formed on the second drilled hole, which can be achieved by adjusting the resin plugging parameters, for example, changing the squeegee pressure and speed to make the resin accumulate in the central area. Specifically, the protrusion structure is formed by optimizing the resin viscosity and the number of plugging cycles, mainly to serve as a removable part in the subsequent grinding process. In practical applications, the support platform maintains structural stability after thermosetting and is removed during the grinding process, thereby making the surface of the second drill hole consistent with the height of the plate.

[0024] This invention utilizes a design in the ink application area to form a support platform on the second drilled hole, which is then removed during the grinding process. This avoids the problem of inconsistent resin height caused by differences in hole diameter. Thus, during grinding, the support platform acts as a sacrificial layer, absorbing additional grinding material and preventing excessive grinding of the resin within the hole. This effectively solves the problem of uneven grinding and resin depressions caused by differences in resin filling height when large and small diameter holes coexist, ensuring the flatness of the PCB board surface. Specifically, this method uses a differentiated filling mechanism to achieve a moderate resin height in the small hole area and a controllable protrusion in the large hole area, resulting in a uniform overall surface after grinding.

[0025] In the PCB manufacturing process, a multilayer circuit board substrate is first obtained, and then drilled to form a first and second hole. The first hole corresponds to a standard small-diameter hole, while the second hole corresponds to a large-diameter hole. This design distinction lays the foundation for subsequent differentiated resin filling. A stencil is fabricated, with its ink application area precisely matched to the second hole position. This ink application area design ensures that resin is concentrated only in specific areas of the large-diameter holes during resin filling. Subsequently, the stencil is mounted on a resin filling device, and pressure is applied using a squeegee. The resin is evenly distributed through the mesh into the first hole for complete filling. Simultaneously, a raised support platform is formed in the ink application area of ​​the second hole. This support platform acts as a sacrificial layer to absorb additional grinding. After resin filling, the multilayer board is placed in an oven for thermosetting, allowing the resin to fully cross-link and stabilize the structure, while the support platform maintains its integrity. Finally, the board surface is processed using a grinding machine, removing only the raised support platform while leaving the resin filling layer inside the first and second holes unaffected, thus ensuring that the surface of all hole areas is consistent with the board surface height.

[0026] Specifically, in practical applications, the second drilled hole can be a circular hole with a diameter greater than 3.0 mm. The diameter of the ink-applying area of ​​the screen is set to be smaller than the diameter of the second drilled hole, so that a resin boss with a height of about 0.2 mm is formed at the center of the hole during the filling process, serving as a support platform. The resin filling process uses epoxy resin, and the squeegee pressure is controlled at 3.0 kgf / cm² to ensure that the support platform is uniformly formed and well bonded to the hole wall. The thermosetting process is carried out in stages: the initial stage is maintained at 90°C for 45 minutes, followed by raising the temperature to 150°C and maintaining it for 90 minutes to allow the resin to fully cure without generating internal stress. The grinding process uses a silicon carbide grinding wheel with a linear speed set to 15 m / s. By precisely controlling the grinding depth, only the support platform portion is removed, avoiding contact with the resin layer inside the hole.

[0027] Therefore, this technical solution effectively eliminates the problem of inconsistent resin filling height caused by differences in pore size through the removable support platform. During the grinding process, the support platform preferentially bears the grinding action and is completely removed, thereby preventing excessive grinding of resin in large-pore areas, which could lead to depressions or wear through, and ensuring that the overall flatness of the board surface meets the process requirements. Furthermore, this method avoids the reliability risks caused by prolonged grinding time in traditional processes, ensuring that the surface condition of both large and small pore areas meets the precision requirements of subsequent outer layer circuit fabrication, significantly improving the electrical performance stability and environmental reliability of the product.

[0028] Specifically, in some embodiments of the present invention, an ink-dip region is proposed to form a support platform on the second drill hole. However, in its implementation, the diameter of the ink-dip region is not limited to be smaller than the diameter of the second drill hole, resulting in an excessively large support platform size. In the subsequent grinding process, the contact area between the resin and the grinding brush in the large hole area increases, causing the resin to be over-ground, forming resin depressions at the edge of the hole, which affects the flatness of the board surface and the reliability of the product.

[0029] In one embodiment of the above steps, it is proposed that the diameter of the ink-applying area is smaller than the diameter of the second drilled hole. Specifically, the diameter of the ink-applying area refers to the size of the ink-applying area set in the center of the second drilled hole position on the stencil. It can be achieved by any proportion smaller than the diameter of the second drilled hole, for example, by adjusting the exposure parameters or etching depth in the stencil manufacturing process to control the size range of the ink-applying area. The diameter of the second drilled hole refers to the hole diameter of the second drilled hole on the PCB multilayer board, which can be the equivalent diameter of a circular hole or an irregularly shaped hole formed by a standard drilling process. The purpose of introducing this technical feature is to limit the size range of the support platform, avoid excessive resin grinding due to excessive contact area during the grinding process, and thus ensure that the support platform only covers the central area of ​​the hole diameter.

[0030] Specifically, the solution of this invention sets the diameter of the ink application area to be smaller than the diameter of the second drilled hole. During the resin plugging process, a size-constrained support platform is formed only in the central region of the second drilled hole, rather than covering the entire hole diameter. During the grinding stage, the smaller support platform reduces the initial contact area with the grinding brush, allowing the grinding force to be distributed more evenly across the board surface and preventing excessive resin removal from large holes. Because the support platform does not extend to the edge of the hole wall, a uniform curing state of the resin within the hole is maintained, optimizing the stress transmission path during the grinding process and ultimately avoiding resin depression defects at the hole opening.

[0031] As a preferred embodiment, the present invention is implemented as follows: During the screen printing process, for the second drilled hole position, a circular ink-dip area smaller than the diameter of the second drilled hole is formed on the aluminum screen using photolithography. This ink-dip area is precisely located at the center of the second drilled hole, ensuring that a support platform is formed only in the center area of ​​the hole during resin plugging. The size of this ink-dip area is generalized and controlled by adjusting the contour of the photolithographic mask.

[0032] Through the above solution, the present invention effectively prevents excessive removal of resin in the large-hole area during the grinding process, avoids resin depression defects at the edge of the hole, and thus ensures the overall flatness of the PCB board surface and the stability of the product's electrical performance.

[0033] In another embodiment of the above steps, the present invention proposes to form a support platform on the second drill hole through the ink application area to balance the resin height difference. However, when the second drill hole is a large diameter hole, due to the significant increase in resin filling volume, it is easy to preferentially contact the grinding brush and suffer excessive grinding during the grinding process, resulting in resin depression at the hole opening or wear through the underlying substrate, affecting the electrical performance and reliability of the product.

[0034] In this invention, the second drill hole can be set as an irregular hole with a diameter greater than 3.0 mm, an irregular groove with a width greater than 3.0 mm, or an irregular groove with a length greater than 3.0 mm. Specifically, an irregular hole with a diameter greater than 3.0 mm refers to a non-standard circular hole with a diameter exceeding 3.0 mm, which can be implemented using elliptical, rectangular, or polygonal shapes, etc., to identify large-diameter hole types that are prone to resin depressions during the grinding process; an irregular groove with a width greater than 3.0 mm refers to a groove-shaped hole with a width dimension greater than 3.0 mm, which can be represented as a U-shaped groove or a T-shaped groove, etc., to optimize the uniformity of resin filling for grooves with larger widths; an irregular groove with a length greater than 3.0 mm refers to a groove-shaped hole with a length dimension greater than 3.0 mm, which can be designed as a long strip groove, to adapt to the problem of uneven grinding in the length direction.

[0035] Specifically, the present invention defines the second drill hole as a large-diameter hole of a specific size and shape, enabling targeted design of the ink application area in the resin-filled printing process. This effectively controls the resin height difference during the thermosetting and grinding stages, avoiding over-grinding caused by excessively large pore sizes. This limitation is based on the critical point where grinding problems significantly worsen in actual production, guiding the screen ink application area to adapt to the pore size characteristics, ensuring that the resin filling volume matches the grinding parameters, and forming a complete process control chain.

[0036] As a specific implementation method, the solution of the present invention is implemented as follows: the second drill hole can be specifically an elliptical hole with a major axis dimension greater than 3.0 mm to match the size design of the ink application area; or, the second drill hole can be specifically a U-shaped groove with a groove width greater than 3.0 mm to optimize the uniformity of resin distribution in the groove width direction.

[0037] Through the above solution, the present invention effectively avoids the problem of resin sinking or grinding through the underlying substrate during the grinding process of large-diameter holes, ensuring the flatness of the PCB board surface and the reliability of electrical connections.

[0038] Example 2: Based on Example 1, the present invention provides a second embodiment of the PCB manufacturing method for improving large-diameter resin plugging vias, to further define steps 110-150 in Example 1.

[0039] Specifically, in step 110, the present invention proposes to drill holes in a PCB multilayer board to create a first drill hole and a second drill hole, specifically including: creating the first drill hole and the second drill hole by mechanical drilling and / or laser drilling.

[0040] In this embodiment, mechanical drilling refers to the process of drilling holes in a multilayer PCB board using a rotary drill bit. It can be achieved using a high-speed drilling machine or CNC drilling equipment. The purpose is to efficiently process large-diameter holes, avoid thermal damage to the hole walls, and ensure a smooth surface. Laser drilling refers to the process of drilling holes in a multilayer PCB board using a high-energy laser beam. It can be achieved using CO2 laser or UV laser equipment. The purpose is to provide micron-level precision drilling capabilities, which is suitable for processing micro-hole structures.

[0041] Specifically, the present invention dynamically matches drilling technology according to pore size characteristics. For the second pore with a large pore size, mechanical drilling is preferentially used to avoid the risk of heat-affected zone expansion in large-size applications using laser drilling, thereby obtaining a uniform pore wall morphology. Simultaneously, laser drilling is used for the first pore with a small pore size, utilizing its non-contact processing characteristics to achieve high-precision pore shape control. This differentiated drilling strategy ensures consistent pore wall quality across different pore size regions, providing a uniform filling interface for subsequent resin plugging and effectively suppressing uneven resin flow caused by pore wall defects.

[0042] As a specific implementation method, the present invention is implemented as follows: For the first borehole with a diameter less than 0.4 mm, a UV laser drilling device is used for non-contact drilling to form a regular hole wall structure; for the second borehole with a diameter greater than 3.0 mm, a carbide drill bit is used in conjunction with a constant pressure feed mechanical drilling device to ensure that the hole wall is burr-free and the surface roughness meets the standard.

[0043] Through the above solution, the present invention effectively solves the negative impact of poor hole wall quality of large diameter holes on resin filling uniformity, avoids excessive grinding caused by resin height difference in the grinding process, and thus ensures the flatness of PCB board surface and the reliability of electrical connection.

[0044] In step 120, the specific steps of making the stencil include: making the stencil according to the pad image and hole size of the PCB multilayer board; wherein, the stencil has uniform mesh holes at both the first and second drilling positions, and the stencil has an ink application area in the middle of the second drilling position, wherein the stencil is an aluminum sheet stencil.

[0045] In this embodiment, creating a stencil based on the pad images and aperture sizes of the PCB multilayer board refers to customizing the stencil pattern based on the actual PCB structural data. Specifically, computer-aided design software can be used to import design files and generate a precise layout. The purpose is to ensure a strict match between the stencil and the drilled hole positions, avoiding the risk of misalignment of the ink application area due to differences in aperture size. The stencil having uniformly distributed holes at both the first and second drilled hole positions means that the size and spacing of the holes distributed on the stencil are consistent. Specifically, laser micromachining or chemical etching processes can be used to form a regularly arranged microporous structure. The purpose is to ensure uniform resin distribution, creating small-aperture areas. It provides a reliable filling base while preventing localized resin buildup in large-aperture areas; the ink-feeding area in the middle of the second drilled hole position of the screen refers to a specific area reserved on the screen to allow resin to pass through. This can be achieved by forming an opening in the middle of the screen or using a soluble mask material. Its purpose is to restrict the resin to flow only into the middle of the hole to form a support platform, significantly reducing the resin volume in large-aperture areas; the screen is made of aluminum sheet, specifically thin aluminum plates that have been precision stamped or etched. Its purpose is to provide sufficient mechanical strength and geometric stability to avoid resin filling deviation due to deformation during printing.

[0046] Specifically, the solution of this invention ensures that the stencil design precisely corresponds to the actual drilling layout by customizing the stencil based on the pad images and hole sizes of the PCB multilayer board. The uniform mesh size of the stencil at the first and second drilling positions ensures even resin distribution, maintaining reliable filling for the small-diameter first drilling and providing a basic filling framework for the large-diameter second drilling. The ink-dip area in the middle of the second drilling position restricts resin flow only to the center of the hole, forming a support platform and significantly reducing the resin volume in the large-diameter area, creating highly consistent surface conditions for the grinding process. The aluminum sheet stencil ensures the geometric stability and durability of the ink-dip area during printing, preventing resin filling deviations due to stencil deformation. These features work together to minimize the surface height difference between large and small holes after resin filling, fundamentally eliminating the risk of resin depressions caused by uneven grinding.

[0047] As a preferred embodiment, the present invention is implemented as follows: a CAM system is used to read the PCB design file and extract the pad image and hole size data; based on this data, a stencil is made on an aluminum sheet by laser cutting, wherein a circular ink-dip area is set in the center of the second drilled hole position, and the surrounding area is covered with an ink-blocking layer; the stencil has uniformly distributed micropore structures at both the first and second drilled hole positions to ensure that the resin is uniformly filled to the designated area during the printing process.

[0048] Through the above solution, the present invention effectively avoids the problem of uneven resin filling caused by inaccurate screen printing, ensures the precise formation of the support platform, thereby preventing resin depression or wear-through defects after grinding, and improving the reliability of the PCB manufacturing process and the product yield.

[0049] In step 130, resin filling is performed on the PCB multilayer board using a resin filling device. Specifically, this includes: scraping resin into the first and second drilled holes through the mesh of a screen, and forming a support platform on the second drilled hole through the ink application area. (See also...) Figure 3 .

[0050] In this embodiment, the mesh of the screen refers to the microstructure channels on the screen used for resin transfer. It can be achieved by forming a regular array of holes on the aluminum substrate using laser micromachining or chemical etching processes. The purpose is to ensure that the resin is evenly distributed and synchronously filled into all the holes during the printing process, avoiding height inconsistencies caused by differences in filling rate. The ink-laying area can be understood as a resin deposition control area specifically designed on the screen. It can be formed in the middle of the screen using a local masking layer or a gradient aperture structure. The purpose is to precisely limit the resin deposition range in the large-aperture holes and prevent the resin from overfilling into the depth area of ​​the holes.

[0051] Specifically, the present invention achieves a special filling mechanism for large-diameter holes through precise control of the resin filling process. Resin is scraped into the first and second drilled holes through the mesh of a screen. The uniform mesh structure allows the resin to simultaneously establish a basic filling layer in both holes, ensuring sufficient filling of the smaller-diameter first hole while providing a uniform initial filling base for the larger-diameter second hole. Based on this, a support platform is formed on the second drilled hole through the ink application area. Due to the dimensional constraints of the ink application area, resin is concentrated and deposited only at the opening of the second drilled hole, forming a raised platform structure rather than filling the entire hole depth. The height of this platform structure is designed to match the height of the filling surface of the first drilled hole. During subsequent thermosetting and grinding processes, the height difference between the two surfaces is significantly reduced, thus preventing the large-diameter area from being preferentially subjected to excessive grinding due to its protruding height.

[0052] As a specific implementation method, the present invention is carried out as follows: During the resin-filled printing process, the prepared liquid resin is uniformly coated on the surface of the aluminum screen printing plate. A squeegee is used to move along the surface of the screen printing plate with constant pressure, allowing the resin to enter the first and second drilled holes through the mesh of the screen printing plate. For the second drilled hole, due to the physical limitation of the ink-laying area in the middle of the screen printing plate, the resin is deposited only in the hole opening area to form a raised support platform, while the first drilled hole is completely filled with resin up to the top of the hole. After curing, the surface height of the support platform is basically consistent with the surface height of the first drilled hole after filling.

[0053] Through the above solution, the present invention effectively solves the problem of significant difference between the resin filling height of large-diameter holes and that of small holes, avoids excessive resin removal in the large-hole area due to height difference during the grinding process, thereby eliminating hole opening depression defects and ensuring the overall flatness and structural reliability of the PCB board surface.

[0054] In step 140, see Figure 2 The thermosetting process includes the following steps: 210. The first stage of baking is carried out on the PCB multilayer board at a baking temperature of 80°C-100°C and a baking time of 30min-60min. 220, the PCB multilayer board is baked in the second stage at a baking temperature of 140°C-160°C and a baking time of 60min-120min; 230, the baking temperature of the baking oven is controlled at the first temperature threshold to perform the third stage baking of the PCB multilayer board with a cooling rate of ≤4°C / min.

[0055] In steps 210-230, the first stage of baking refers to the process of preliminary curing of the resin under relatively low temperature conditions, which can be achieved by step heating or constant temperature. The purpose is to allow the resin to undergo a slow cross-linking reaction, avoiding burst polymerization and uneven initial shrinkage caused by a sudden temperature rise. The second stage of baking can be understood as the stage of promoting complete curing of the resin at a higher temperature. It can be implemented by constant temperature baking or fine-tuning the temperature. The purpose is to ensure that the resin obtains sufficient mechanical strength, while controlling the degree of shrinkage to maintain the integrity of the resin structure within the pores. The third stage of baking is a cooling process achieved by precisely controlling the cooling rate, such as by using programmed cooling or segmented cooling. The purpose is to reduce the accumulation of thermal stress and prevent deformation or cracking of the resin due to internal stress caused by excessively rapid temperature changes.

[0056] Specifically, the present invention employs a segmented thermosetting process to precisely control the resin curing process. First, a first-stage baking is performed at a temperature range of 80°C to 100°C for 30 to 60 minutes, allowing the resin to slowly pre-cur at a low temperature. This avoids the explosive polymerization reaction and excessive initial shrinkage caused by rapid temperature rise, especially important for the large volume and high heat capacity of the resin in the large-pore area. This stage ensures uniform heat penetration and reduces localized shrinkage differences. Second, a second-stage baking is performed at a temperature range of 140°C to 160°C for 60 to 120 minutes. This moderate temperature promotes full cross-linking and curing of the resin, providing stable mechanical strength, while preventing excessive shrinkage due to excessively high temperatures, thus maintaining the structural integrity and high consistency of the support platform. Finally, a third-stage baking is performed at a cooling rate not exceeding 4°C per minute, controlling the baking temperature to the first temperature threshold. This slow cooling process significantly reduces thermal stress accumulation, preventing cracking or deformation of the resin due to rapid cooling, thereby ensuring overall high uniformity and providing a smooth foundation for subsequent grinding processes.

[0057] As a specific implementation method, the present invention is implemented as follows: After the PCB multilayer board after resin filling treatment enters the baking oven, the baking temperature is first set to 90°C and maintained for 45 minutes for the first stage of baking; then the temperature is raised to 150°C and maintained for 90 minutes for the second stage of baking; finally, the temperature is lowered to 50°C at a cooling rate of 3°C / min for the third stage of baking.

[0058] Through the above solution, the present invention effectively solves the problem of significant shrinkage of resin in large-pore areas due to its large volume, ensures the consistency of the support platform height, and avoids the phenomenon of large-pore resin being over-ground and forming depressions or wear through during the grinding process, thereby improving the surface flatness of the PCB board and the product quality.

[0059] In step 150, the PCB multilayer board is ground to remove the support platform, specifically including: The surface of the PCB multilayer board is ground by the grinding wheel of the grinding equipment to make the surface of the first and second drilled holes consistent with the height of the PCB multilayer board surface.

[0060] In this embodiment, the grinding wheel of the grinding equipment refers to a rotating tool used to perform the grinding function on the PCB surface. It can be a diamond grinding wheel or an alumina grinding wheel, and its purpose is to provide a stable and uniform grinding force distribution. Making the surface of the first and second drilled holes consistent with the surface of the PCB multilayer board means to achieve the flattening of the hole surface by controlling the grinding endpoint. Its purpose is to eliminate the resin height deviation caused by the difference in hole diameter and ensure the overall board surface consistency.

[0061] Specifically, the present invention applies a uniform grinding force to the surface of a PCB multilayer board using a grinding wheel of a grinding equipment. The rigid structure of the grinding wheel can accommodate the large resin volume of the large-diameter second drill hole, avoiding local over-grinding caused by differences in hole diameter in traditional grinding methods. At the same time, the grinding process continues until the surfaces of the first and second drill holes reach the same height as the PCB multilayer board surface. This consistent height is directly achieved through the uniform grinding characteristics of the grinding wheel and the endpoint control mechanism, thus forming a complete technical system that effectively solves the problem of uneven grinding.

[0062] As a preferred embodiment, the present invention is implemented as follows: the grinding equipment is a surface grinding machine, and the grinding wheel is a resin-bonded diamond grinding wheel; the PCB multilayer board is fixed on the worktable, and the grinding wheel rotates at a constant pressure to grind the surface. The operator stops the grinding operation after confirming that the hole surface is flush with the board surface by visual observation or simple optical inspection tools.

[0063] Through the above solution, the present invention effectively prevents resin depression or wear-through caused by uneven grinding in the resin plugging process of large-diameter holes, and ensures the high consistency between the surface of the first and second drilled holes and the surface of the PCB multilayer board, thereby ensuring the overall flatness of the board surface and the reliability of subsequent outer layer circuit fabrication, electroplating and other processes.

[0064] In some implementations, after grinding the PCB multilayer board and removing the support platform, the process also includes outer layer circuit fabrication, electroplating, solder mask treatment, surface treatment, molding treatment, and inspection treatment to generate the target PCB board.

[0065] In this embodiment, outer layer circuit fabrication refers to the process of forming conductive lines on the PCB surface, which can be achieved using photolithography or etching techniques. The aim is to define circuit patterns with high precision based on the uniform surface after grinding, reducing the risk of short circuits or open circuits. Electroplating refers to the process of depositing a metal layer on the conductive surface, which can be achieved using chemical plating or electroplating methods. The aim is to strengthen conductive paths and fill micropores, enhancing the product's corrosion resistance and long-term electrical reliability. Solder resist treatment refers to the process of coating a protective layer on non-soldering areas, which can be achieved using liquid photosensitive solder resist ink or dry film solder resist, aiming to precisely cover the non-soldering areas. The process involves several steps: First, the bonding area is designed to prevent short circuits caused by solder balls during assembly. Second, surface treatment optimizes the metallic properties of the PCB surface, using chemical nickel plating or organic solderability protectants to improve the adhesion and consistency of solder joints. Third, forming is the process of cutting the PCB into its final shape, using CNC milling machines or stamping equipment to ensure precise dimensional accuracy and prevent deformation caused by early stress. Fourth, inspection is a comprehensive quality assessment of the PCB, using flying probe testing or automated optical inspection to identify and remove potentially defective products.

[0066] Specifically, the present invention seamlessly integrates the polished PCB multilayer board into a standard manufacturing process. First, the smooth surface created by polishing serves as the basis for outer layer circuitry, ensuring high-precision definition of the circuit pattern. Then, electroplating is performed on the smoothed surface to effectively strengthen conductive paths and fill micropores. Next, solder mask treatment is applied, precisely covering non-soldering areas based on the completed circuit structure. Following this, surface treatment is performed to optimize the activity of the metal interface. Then, forming is carried out, and the board is cut according to precise dimensional standards after all functional steps. Finally, a comprehensive evaluation of electrical performance and physical properties is conducted through inspection. These steps are executed sequentially, forming a complete technical system that ensures surface defects are systematically eliminated in subsequent processes, thereby mitigating the risk of defect continuation.

[0067] As a preferred embodiment, the present invention is implemented as follows: After grinding to remove the support platform, the outer layer circuitry is first fabricated by using photolithography to form a fine circuit pattern on the surface of the PCB multilayer board; then electroplating is performed, using a chemical copper plating process to deposit a uniform copper layer in the conductive areas; next, solder resist treatment is performed, applying liquid photosensitive solder resist ink to cover the non-soldering areas; then surface treatment is performed, using a chemical nickel-gold process to optimize the surface of the solder pads; after that, shaping is performed, using a CNC milling machine to cut the board to the specified shape; finally, testing is completed, and the electrical performance is verified by flying probe testing.

[0068] Through the above solution, the present invention ensures that the PCB board meets reliable standards in terms of electrical performance and structural integrity, avoids process deviations caused by surface unevenness, improves the functional stability of the product in complex environments, and meets the quality requirements of high-end applications.

[0069] Example 3: Based on Embodiment 1 or Embodiment 2, the present invention proposes a PCB manufacturing apparatus for improving large-diameter resin-filled vias, used to execute the PCB manufacturing method for improving large-diameter resin-filled vias in Embodiment 1 or Embodiment 2, and to manufacture printed circuit boards.

[0070] This device designs the diameter of the ink-applying area of ​​the stencil to be smaller than the diameter of the second drilled hole, creating a locally raised support platform on the second drilled hole. This support platform is precisely removed as a sacrificial layer during the grinding process, thus avoiding over-grinding of the resin in the large-hole area. This effectively solves the problems of uneven grinding and resin depression caused by differences in hole diameter, ensuring the flatness of the PCB board surface. Specifically, the size limitation of the ink-applying area ensures that the support platform forms a raised structure only in the central area of ​​the second drilled hole. The grinding unit removes only this support platform portion using a grinding wheel, making the surfaces of the first and second drilled holes have the same height. At the same time, the baking unit uses segmented temperature control to perform thermosetting treatment on the resin, ensuring that the resin is fully cross-linked without generating internal stress, further improving the high uniformity during the grinding process. Through the above mechanism, this invention eliminates the grinding challenges caused by differences in hole diameter from the source of the process, rather than relying on passive compensation by adjusting grinding parameters, significantly improving the electrical performance stability and environmental reliability of the product.

[0071] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0072] Those skilled in the art will understand that the modules in the device of the embodiment can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiment can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.

[0073] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several systems, several of these systems may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A method for manufacturing a PCB with improved large-diameter resin-filled vias, characterized in that, The method includes: Obtain a multilayer PCB board and drill holes in the multilayer PCB board to create a first drill hole and a second drill hole. A screen printing plate is made, and the screen printing plate has an ink application area that matches the position of the second drill hole; The screen is mounted on the resin plugging device, and the resin plugging device is used to perform resin plugging on the PCB multilayer board, and a support platform is formed on the second drill hole through the ink application area. The resin-impregnated PCB multilayer board is then placed in an oven for thermosetting. The PCB multilayer board is ground to remove the support platform.

2. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 1, characterized in that, The diameter of the ink-dip region is smaller than the diameter of the second borehole.

3. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 2, characterized in that, The second drilled hole is an irregular hole with a diameter greater than 3.0 mm, or an irregular groove with a width greater than 3.0 mm, or an irregular groove with a length greater than 3.0 mm.

4. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 3, characterized in that, Drilling is performed on the PCB multilayer board to create a first drilled hole and a second drilled hole, specifically including: The first and second holes are made by mechanical drilling and / or laser drilling.

5. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 4, characterized in that, Creating a screen print specifically includes: A stencil is fabricated based on the pad image and aperture size of the PCB multilayer board; wherein the stencil has uniform mesh holes at both the first and second drill hole positions, and an ink application area is provided in the middle of the second drill hole position; wherein the stencil is an aluminum sheet stencil.

6. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 5, characterized in that, The PCB multilayer board is resin-filled using a resin-filling device, specifically including: Resin is scraped into the first and second drill holes through the mesh of the screen, and a support platform is formed on the second drill hole through the ink application area.

7. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 6, characterized in that, The resin-impregnated PCB multilayer board is then placed in an oven for thermosetting, specifically including: The first stage of baking was carried out on the PCB multilayer board at a baking temperature of 80°C-100°C and a baking time of 30min-60min. The PCB multilayer board was baked in the second stage at a baking temperature of 140°C-160°C and a baking time of 60min-120min. The baking temperature of the baking oven is controlled at the first temperature threshold at a cooling rate of ≤4°C / min to perform the third stage baking of the PCB multilayer board.

8. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 6, characterized in that, Grinding the PCB multilayer board to remove the support platform specifically includes: The surface of the PCB multilayer board is ground by the grinding wheel of the grinding equipment to make the surface of the first and second drilled holes consistent with the height of the PCB multilayer board surface.

9. The PCB fabrication method for improving large-diameter resin-filled vias according to claim 1, characterized in that, After grinding the PCB multilayer board and removing the support platform, the process also includes outer layer circuit fabrication, electroplating, solder mask treatment, surface treatment, forming treatment, and inspection treatment to generate the target PCB board.

10. A PCB fabrication apparatus for improving large-diameter resin-filled vias, characterized in that, The apparatus is used to perform the PCB manufacturing method for improving large-diameter resin plugging according to any one of claims 1-9, and to manufacture a printed circuit board.

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