Circuit board hole plugging method and circuit board

Abstract

The invention provides a circuit board hole plugging method and a circuit board. The method comprises the following steps: providing a circuit board with at least two communicating holes, wherein the apertures of the at least two communicating holes are unequal; wherein in the thickness direction of the circuit board, the circuit board is provided with a first surface and a second surface which are oppositely arranged; placing a first mask plate on one of the first surface and the second surface of the circuit board; executing a first filling process, and filling the preset depth of the communication hole with the minimum hole diameter; removing the first mask plate, and placing a second mask plate on the other one of the first surface and the second surface of the circuit board; and executing a second filling process to fill the at least two communication holes so as to form a filling structure in each communication hole. Therefore, the effects of reducing the hole plugging cost of the circuit board and improving the hole plugging quality are achieved.

Description

Technical Field

[0001] This application relates to the field of circuit board manufacturing technology, specifically to a method for plugging vias in a circuit board and a circuit board. Background Technology

[0002] Printed circuit boards (PCBs) are critical components in electronic devices, and their manufacturing technology directly impacts the performance and reliability of these devices. In PCB manufacturing, via plugging is a common process, primarily used to fill vias to allow for electroplating on the surface, thereby enabling electrical connections on the circuit board. However, the effectiveness of via plugging can vary depending on the via diameter; therefore, developing high-quality via plugging methods for circuit boards has become a promising area for application.

[0003] In existing technologies, the common method is to first plug the small holes on one side of the circuit board, and then plug the large holes, so as to ensure that each hole is effectively filled.

[0004] However, in existing technologies, uneven filling effects are caused by differences in aperture size. Small holes are prone to poor conductivity, while large holes are prone to overfilling, increasing the difficulty of grinding. Step-by-step via plugging requires multiple operations, leading to resin material waste and a surge in labor costs. Furthermore, the additional grinding process further extends the production cycle. Repeated mechanical processing disrupts the uniformity of copper thickness, resulting in unstable circuit performance. The combination of these problems leads to the technical issues of high cost and low quality of via plugging in existing circuit boards. Summary of the Invention

[0005] This application provides a circuit board via plugging method and a circuit board, which can solve the technical problems of high cost and low quality of existing circuit board via plugging.

[0006] On one hand, this application provides a method for plugging vias in a circuit board, comprising:

[0007] A circuit board is provided having at least two through holes, the diameters of the at least two through holes being unequal; wherein, along the thickness direction of the circuit board, the circuit board has a first surface and a second surface disposed opposite to each other;

[0008] A first mask is placed on one of a first surface and a second surface of a circuit board; wherein the first mask includes a first opening that exposes the smallest of at least two connecting holes;

[0009] Perform the first filling process to fill the preset depth of the connecting hole with the smallest aperture;

[0010] Remove the first mask and place a second mask on the other of the first and second surfaces of the circuit board; wherein the second mask has at least two second openings that expose corresponding connecting holes;

[0011] A second filling process is performed to fill at least two connecting holes to form a filling structure in each connecting hole.

[0012] According to one embodiment of this application, a first filling process is performed to fill a preset depth of the connecting hole with the smallest aperture, including:

[0013] Place the circuit board in the vacuum plugging machine;

[0014] The smallest aperture connecting hole is filled from the first surface using a filling material, such that the filling material fills to a preset depth of the smallest aperture connecting hole.

[0015] The process parameters of the first filling process are determined by the diameter of the smallest connecting hole.

[0016] According to one embodiment of this application, a second filling process is performed to fill at least two connecting holes, including:

[0017] Flip the circuit board so that the second surface faces the filling head of the vacuum plugging machine;

[0018] In the second filling process of the vacuum plugging machine, filling material is used to fill all the connecting holes from the second surface so that all the connecting holes are at least fully filled.

[0019] The second filling process is determined by the diameter of all the connecting holes, and the second filling process is calculated based on the compensation system corresponding to all the connecting holes.

[0020] According to one embodiment of this application, if the diameter of the smallest connecting hole is less than or equal to 0.2 mm, then the preset depth is two-thirds of the circuit board thickness.

[0021] If the diameter of the smallest connecting hole is greater than 0.2mm and less than 0.3mm, the preset depth is one-third of the circuit board thickness.

[0022] According to one embodiment of this application, before electroplating the inner walls of the first through hole and the second through hole, the method further includes:

[0023] Metal is deposited onto the inner walls of the first and second through holes to form a third metal layer.

[0024] According to one embodiment of this application, at least two connecting holes include a first connecting hole and a second connecting hole; the diameter of the first connecting hole is 0.2 mm, and the diameter of the second connecting hole is 0.5 mm.

[0025] According to one embodiment of this application, the process parameters of the first filling process include at least one of the following:

[0026] The plugging pressure is greater than 1.5 MPa;

[0027] The vacuum level of the vacuum plugging machine is 10 Pa to 100 Pa;

[0028] The vacuum dwell time is 10 to 30 seconds.

[0029] According to one embodiment of this application, in the second filling process of a vacuum plugging machine, the step of filling all the interconnecting holes from the second surface with filling material includes:

[0030] The first sub-filling process is performed to fill a portion of the depth of all the connecting holes; the pressure of the first sub-filling process is 1.55MPa to 25MPa, and the vacuum degree of the first sub-filling process is 10Pa to 100Pa.

[0031] The second sub-filling process is performed to fill the remaining depth of all the connecting holes so that all the connecting holes are at least fully filled. The pressure of the second sub-filling process is 2 MPa to 3 MPa, the vacuum degree of the second sub-filling process is 10 Pa to 100 Pa, and the vacuum degree of the second sub-filling process is less than that of the first sub-filling process.

[0032] According to one embodiment of this application, after performing the second filling process to fill at least two connecting holes, the process further includes:

[0033] Perform a baking process to solidify the filling material that has been filled into at least two interconnected holes;

[0034] A grinding process is used to remove the filler material on the circuit board, leaving the filler material in the through hole so that one end of the filler material in the through hole is flush with the first surface and the other end of the filler material in the through hole is flush with the second surface.

[0035] According to one embodiment of this application, a grinding process is used to remove filler material located on a circuit board, including:

[0036] The first grinding process is performed to grind the circuit board for the first time; the grinding material for the first grinding process is abrasive belt.

[0037] A second polishing process is performed to polish the circuit board a second time; the polishing material for the second polishing process is a ceramic brush.

[0038] The circuit board is then subjected to a third polishing process, in which the polishing material is non-woven fabric.

[0039] On the other hand, the circuit board provided in this application is manufactured by the circuit board via plugging method of the above embodiments;

[0040] The circuit board has two connecting holes, and the diameters of the two connecting holes are different; each connecting hole is filled with a filling structure.

[0041] This application provides a circuit board via-filling method and a circuit board. First, a first mask is used on one side of the circuit board to position and fill the smallest hole. By controlling the preset depth, the problem of insufficient or excessive filling caused by differences in hole diameter in traditional processes is avoided. This ensures that the small hole is completely filled to guarantee conductivity, reduces the amount of resin material used, and eliminates the need for the first full-scale grinding process. Then, the circuit board is flipped over and a second mask is used to fill all holes as a whole. The support structure formed by the previous filling effectively improves the uniformity of filling large holes and avoids grinding difficulties caused by overfilling. At the same time, a single whole filling replaces multiple operations, significantly shortening the process cycle and reducing labor costs. Finally, through a double-sided collaborative filling mechanism, the technical problems of high cost and low quality of via-filling in existing circuit boards are systematically solved while ensuring filling reliability. This achieves the effect of reducing via-filling cost and improving via-filling quality. Attached Figure Description

[0042] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0043] Figure 1 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 1 ;

[0044] Figure 2 A schematic diagram of the circuit board via plugging process provided in an embodiment of this application;

[0045] Figure 3 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 2 ;

[0046] Figure 4 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 3 ;

[0047] Figure 5 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 4 ;

[0048] Figure 6 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 5 ;

[0049] Figure 7 This is a cross-sectional view of the circuit board provided in an embodiment of this application.

[0050] Explanation of reference numerals in the attached figures:

[0051] 100: Circuit board;

[0052] 110: First surface;

[0053] 120: Second surface;

[0054] 130: Connecting hole;

[0055] 200: First mask;

[0056] 300: Second mask;

[0057] 400: Air cushion plate;

[0058] 410: Air vent.

[0059] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0060] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. Clearly, the described embodiments are only a portion, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0061] Printed circuit boards (PCBs) are the support structures for electronic components. In this application, they are simply referred to as circuit boards. The circuit boards described in this application can be used in various electrical devices, and no particular type of electrical device is limited to this application.

[0062] A circuit board consists of multiple layers of core boards. These core boards can be stacked and laminated along their thickness to form a complete circuit board. The complete board typically has various holes for electrical conduction, positioning, heat dissipation, and separation.

[0063] In circuit board manufacturing, via plugging is a common process used to fill vias so that electroplating can be performed on the surface of the holes, thereby enabling electrical connections on the circuit board. However, the effectiveness of via plugging can vary depending on the size of the via.

[0064] In existing technologies, the common method is to first plug the small holes on one side of the circuit board, and then plug the large holes, so as to ensure that each hole is effectively filled.

[0065] However, uneven filling results due to differences in aperture size lead to poor conductivity in small holes and overfilling in large holes, increasing the difficulty of grinding. Step-by-step plugging requires multiple operations, resulting in resin material waste and a surge in labor costs, and the additional grinding process further extends the production cycle. Repeated mechanical processing disrupts the uniformity of copper thickness, leading to unstable circuit performance. The combination of these problems results in the high cost and low quality of existing circuit board plugging technology.

[0066] Based on the above problems, the applicant has improved the existing circuit board via filling method. In this application, a first mask is first used on one side of the circuit board to position and fill the smallest hole. By controlling the preset depth, the problems of insufficient or excessive filling caused by differences in hole diameter in traditional processes are avoided. This ensures that the small hole is completely filled to guarantee conductivity, reduces the amount of resin material used, and eliminates the need for the first full-scale grinding process. Subsequently, the circuit board is flipped over and a second mask is used to fill all holes as a whole. The support structure formed by the previous filling effectively improves the uniformity of filling large holes and avoids grinding difficulties caused by overfilling. At the same time, a single whole filling replaces multiple operations, significantly shortening the process cycle and reducing labor costs. Finally, through the double-sided collaborative filling mechanism, the technical problems of high cost and low quality of existing circuit board via filling are systematically solved while ensuring filling reliability, achieving the effect of reducing via filling cost and improving via filling quality.

[0067] The method for manufacturing the circuit board 100 provided in this application and the circuit board itself are described below with reference to the accompanying drawings and specific embodiments.

[0068] Figure 1 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 1 , combined Figure 2 The circuit board via plugging process shown in this application embodiment includes the following steps.

[0069] S101. A circuit board is provided having at least two connecting holes, the diameters of the at least two connecting holes being unequal; wherein, along the thickness direction of the circuit board, the circuit board has a first surface and a second surface disposed opposite to each other.

[0070] In this embodiment, the first surface 110 of the circuit board 100 can be the component surface (C surface) or the soldering surface (S surface) of the circuit board 100, while the second surface 120 is the other surface. The C surface usually refers to the main mounting surface of the component, which corresponds to the top layer in a double-sided board. The S surface usually refers to the surface on which the component pins are connected to the circuit board 100 through the solder pads, which corresponds to the bottom layer in a double-sided board.

[0071] A pre-processed circuit board 100 substrate needs to be prepared. The significant feature of this substrate is that multiple through holes 130 of varying diameters are distributed on its surface. These holes can be formed by mechanical drilling or laser drilling. The circuit board 100 has a first surface 110 and a second surface 120 that are symmetrical on both sides. These two surfaces will be used as the processing surfaces in the future.

[0072] It should be noted that all connecting holes 130 penetrate the plate to form vertical channels, and this structural design creates conditions for subsequent filling.

[0073] In one possible implementation, at least two connecting holes 130 include a first connecting hole and a second connecting hole; the diameter of the first connecting hole is 0.2 mm and the diameter of the second connecting hole is 0.5 mm.

[0074] S102. Place a first mask on one of the first surface and the second surface of the circuit board.

[0075] In this embodiment, the first mask 200 includes a first opening that exposes the smallest of at least two connecting holes 130. The mask is essentially a thin metal film with a precision perforated pattern, and a custom aluminum sheet is typically used as the mask.

[0076] A specially designed first mask 200 is covered on any surface of the circuit board 100 (e.g., the first surface 110 is selected).

[0077] S103. Perform the first filling process to fill the preset depth of the connecting hole with the smallest diameter.

[0078] In some examples, when performing the first filling process, epoxy resin can be injected to a preset depth of the smallest connecting hole 130 using a vacuum plugging machine.

[0079] In one possible implementation, if the diameter of the smallest connecting hole 130 is less than or equal to 0.2 mm, then the preset depth is two-thirds of the thickness of the circuit board 100.

[0080] If the diameter of the smallest connecting hole 130 is greater than 0.2mm and less than 0.3mm, then the preset depth is one-third of the thickness of the circuit board 100.

[0081] Optionally, the filling process can be aided by vacuum adsorption with an air guide plate 400 and its corresponding air guide holes 410.

[0082] S104. Remove the first mask and place the second mask on the other of the first and second surfaces of the circuit board.

[0083] In this embodiment, the second mask plate 300 has at least two second openings, and the at least two second openings expose corresponding connecting holes 130.

[0084] In some examples, in step S102 above, if the C-side of the circuit board 100 is determined to be the first surface 110, the first mask 200 of the first surface 110 is removed, and a second mask 300 is placed on the second surface 120, i.e., the S-side, of the circuit board 100.

[0085] It is important to note that during the conversion between the first mask 200 and the second mask 300, the plates must be kept clean to avoid residual resin affecting subsequent alignment accuracy.

[0086] S105. Perform a second filling process to fill at least two connecting holes to form a filling structure in each connecting hole.

[0087] In some examples, when performing the second filling process, epoxy resin can be injected into at least two connecting holes 130 via a vacuum plugging machine to ensure that a filling structure is formed in each connecting hole 130.

[0088] Optionally, the filling process can be aided by vacuum adsorption with an air guide plate 400 and its corresponding air guide holes 410.

[0089] The via-filling method for circuit boards provided in this application first uses a first mask 200 to position and fill the smallest holes on one side of the circuit board 100. By controlling the preset depth, the problem of insufficient or excessive filling caused by differences in hole diameter in traditional processes is avoided. This ensures that the small holes are completely filled to guarantee conductivity, reduces the amount of resin material used, and eliminates the need for the first full-scale grinding process. Then, the circuit board 100 is flipped over and a second mask 300 is used to fill all holes as a whole. The support structure formed by the previous filling effectively improves the uniformity of filling large holes and avoids grinding difficulties caused by overfilling. At the same time, a single overall filling replaces multiple operations, significantly shortening the process cycle and reducing labor costs. Finally, through the double-sided collaborative filling mechanism, the technical problems of high cost and low quality of via filling in existing circuit boards 100 are systematically solved while ensuring filling reliability. This achieves the effect of reducing via filling cost and improving via filling quality.

[0090] Figure 3 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 2 , combined Figure 2 and Figure 3 This application provides a detailed description of the execution process of the first filling process based on the above embodiments, including:

[0091] S301. Place the circuit board in the vacuum plugging machine.

[0092] In one possible implementation, the process parameters of the first filling process include at least one of the following:

[0093] The plugging pressure is greater than 1.5 MPa;

[0094] The vacuum level of the vacuum plugging machine is 10 Pa to 100 Pa;

[0095] The vacuum dwell time is 10 to 30 seconds.

[0096] In some examples, when performing the first filling process, the pre-treated circuit board 100 needs to be precisely positioned on the working platform of the vacuum plugging machine, and the height of the equipment support frame is adjusted according to the thickness of the circuit board 100 to ensure that the levelness error of the board is within the preset range. At the same time, the alignment marks on the circuit board 100 can be precisely aligned with the processing coordinate system of the vacuum plugging machine through the optical positioning system. After the physical positioning is completed, the equipment will start the multi-stage vacuum pump group and control the vacuum degree of the processing chamber within the range of 10Pa to 100Pa according to the preset process parameters.

[0097] S302. Use a filling material to fill the smallest aperture connecting hole from the first surface, so that the filling material fills to a preset depth of the smallest aperture connecting hole.

[0098] In this embodiment, the process parameters of the first filling process are determined by the diameter of the smallest connecting hole 130.

[0099] Optionally, the filler material can be an insulating filler material, such as epoxy resin, or a conductive filler material developed for high-frequency signal transmission requirements.

[0100] It is important to note that the viscosity of the insulating filler material at room temperature is controlled within the range of 800 cPs-1200 cPs to ensure good flowability while preventing excessive seepage and contamination of the solder pads. Nano-sized silica filler is specifically added to the resin formulation, reducing the post-curing shrinkage rate to below 0.3% and effectively preventing crescent-shaped cavities from forming in the center of holes; the conductive filler material can achieve a volume resistivity as low as [missing value] after curing. This level is particularly suitable for creating conductive vias for three-dimensional interconnects.

[0101] In some examples, when proceeding to the actual filling operation, the appropriate filling material (insulating or conductive) is selected based on the characteristics of the minimum pore size.

[0102] During the filling process, the equipment dynamically adjusts process parameters based on real-time data from the pore size detection system. For 0.2mm micropores, a stepped pressurization strategy of 1.5-2MPa is adopted—in the initial stage, a low pressure of 1.5MPa is used to push the resin to overcome capillary resistance. When the filling depth reaches 1 / 3 of the pore diameter, the pressure is automatically increased to 1.8MPa to ensure full filling. At the same time, the vacuum residence time is intelligently controlled. The resin flow front is monitored by an infrared thermal imager built into the chamber. When the 0.2mm pore is filled to the preset depth (e.g., three-half of the pore depth), the system automatically switches to the pressure holding mode, which avoids overfilling and resin overflow, and also prevents insufficient filling and pore wall coverage from being less than 90%.

[0103] The circuit board via plugging method provided in this application creates a sealed low-pressure environment using a vacuum via plugging machine, which can effectively remove residual air in the connecting hole 130, avoiding the formation of voids during filling and providing a stable penetration channel for the filling material. At the same time, the filling pressure and material dosage are precisely controlled according to the minimum pore size characteristics, ensuring that the filling material fully wets the hole wall to form a reliable bond, while preventing material overflow and contamination of the pads through preset depth control. This parameter adaptive mechanism significantly improves the filling integrity of micro-pores and the electrical performance consistency of the circuit board 100.

[0104] Figure 4 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 3 , combined Figure 2 and Figure 4 This application provides supplementary explanations of the execution of the second filling process and subsequent procedures based on the above embodiments, including:

[0105] S401, Flip the circuit board so that the second surface faces the filling head of the vacuum plugging machine.

[0106] In some examples, a precision flipping mechanism rotates the circuit board 100 by 180 degrees, so that the second surface 120, which was originally facing away from the filling head, faces upwards. This action is accomplished using a vacuum suction device on a robotic arm, which avoids deformation of the filled 0.2mm micro-holes due to external force during the flipping process and ensures that the 0.5mm large holes on the second surface are precisely aligned with the filling nozzle assembly of the vacuum plugging machine. In actual operation, the equipment monitors the flatness of the board surface in real time using a laser rangefinder. When a thickness deviation of more than 0.05mm is detected in the epoxy resin filling of the 0.2mm holes, the system automatically compensates for the flipping angle. This dynamic calibration mechanism ensures that the hole alignment accuracy during the filling of the second surface reaches the ±0.02mm level.

[0107] S402. In the second filling process of the vacuum plugging machine, filling material is used to fill all the connecting holes from the second surface so that all the connecting holes are at least fully filled.

[0108] In this embodiment, the second filling process is determined by the diameter of all the connecting holes 130, and the second filling process is calculated based on the compensation system corresponding to all the connecting holes 130.

[0109] In some examples, a full-pore-size intelligent filling strategy is adopted. The device uses a 1.95MPa enhanced pressure mode (1.5MPa base pressure × 1.3 compensation coefficient) for 0.2mm micropores based on a pre-entered pore-size database, while implementing a 1.2MPa depressurization mode (1.5MPa base pressure × 0.8 compensation coefficient) for 0.5mm macropores. This differentiated pressure control ensures that the resin fully penetrates the micropores and prevents the macropores from being overfilled.

[0110] It is important to note that the "filling" in this embodiment includes two typical operating conditions: when using insulating epoxy resin, the filling height will be slightly higher than the board surface by 0.02-0.05mm to form a micro-protrusion structure, leaving machining allowance for subsequent grinding; when using conductive silver paste to create vertical interconnect vias 130, the filling height will be precisely flush with the board surface to ensure reliable ohmic contact between the conductive plug and the pad. The equipment uses a spectral confocal sensor to detect the filling front in real time. When the resin in the 0.2mm hole reaches the hole opening, it automatically switches to the holding pressure mode, while the 0.5mm hole continues to be filled until a capacitance change signal is detected (indicating that the air in the hole has been completely expelled).

[0111] S403. Perform a baking process to cure the filling material that has been filled into at least two interconnected holes.

[0112] The baking process uses a three-stage temperature curve: first, the resin is kept at 80℃ for 30 minutes to complete the B-stage curing, then the temperature is increased to 120℃ at a rate of 2℃ / min for 2 hours for deep curing, and finally it is naturally cooled to room temperature.

[0113] S404. A grinding process is used to remove the filler material on the circuit board, while retaining the filler material in the through hole, so that one end of the filler material in the through hole is flush with the first surface and the other end of the filler material in the through hole is flush with the second surface.

[0114] In some examples, a combined abrasive strategy of sanding belt + ceramic brush + needle brush + non-woven brush can be used to remove the filler material on the circuit board 100, while retaining the filler material in the connecting hole 130, so that one end of the filler material in the connecting hole 130 is flush with the first surface 110 and the other end of the filler material in the connecting hole 130 is flush with the second surface 120.

[0115] The circuit board via-filling method provided in this application flips the circuit board 100 so that the second surface 120 faces upward, ensuring that all connecting holes 130 can be directly covered by the filling head, avoiding uneven filling caused by hole orientation during the first filling. At the same time, an adaptive hole diameter compensation technology is adopted to dynamically adjust the filling pressure and material flow rate according to different hole diameters, preventing resin overflow caused by overfilling of small holes and ensuring that large holes are fully filled to form a complete conductive / insulating structure. In addition, the baking process uses temperature gradient control to gradually cure the filling material, eliminating internal stress and improving bonding strength. Finally, the grinding process precisely removes excess material from the board surface, making the two ends of the filling structure strictly flush with the surface of the circuit board 100, ensuring both the filling density in the holes and improving surface flatness, providing a reliable base for subsequent component mounting.

[0116] Figure 5 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 4 , combined Figure 2 and Figure 5 This application embodiment, based on the above embodiments, provides a detailed description of the filling process for filling all the connecting holes 130 from the second surface, including:

[0117] S501. Perform the first sub-filling process to fill a portion of the depth of all connected holes;

[0118] In this embodiment, the pressure of the first sub-filling process is 1.55MPa to 25MPa, and the vacuum degree of the first sub-filling process is 10Pa to 100Pa; the partial depth specifically refers to the filling target preset according to the pore size difference, and this embodiment does not impose any restrictions on the specific value of the partial depth.

[0119] In some examples, the connecting holes 130 are initially filled by a high-pressure environment of 1.55-25 MPa. This pressure range is designed with fluid dynamics optimization: for 0.2 mm micropores, the instantaneous high pressure of 25 MPa can break through the surface tension of the resin, ensuring that the filling material quickly wets the pore wall; for 0.5 mm macropores, the base pressure of 1.55 MPa combined with a vacuum of 10-100 Pa can both promote resin penetration and avoid overfilling.

[0120] S502. Perform the second sub-filling process to fill the remaining depth of all connected holes so that all connected holes are at least fully filled.

[0121] In this embodiment, the pressure of the second sub-filling process is 2MPa to 3MPa, the vacuum degree of the second sub-filling process is 10Pa to 100Pa, and the vacuum degree of the second sub-filling process is less than that of the first sub-filling process.

[0122] In some examples, after entering the second sub-filling process, the process pressure is adjusted to the range of 2-3 MPa. This parameter design reflects dual technical considerations: for large holes that are not fully filled in the early stage, moderate pressure increase can push the resin to complete the final filling; for small holes that have reached two-thirds of the depth, maintaining the upper limit pressure of 3 MPa can ensure the fullness of filling and avoid resin overflow from the hole opening due to sudden pressure changes.

[0123] It is important to note that when the second sub-process is started, the system automatically reduces the vacuum level from 100Pa to 10Pa. This negative pressure change has a dual effect: on the one hand, it enhances the adhesion of the resin to the pore wall, and on the other hand, it controls the filling rate of large pores through the air pressure difference, so that the resin front of the 0.5mm pore position advances at a controlled speed of 0.8mm / min, ultimately achieving the precise control target that the filling height error of all pore positions is less than or equal to 0.02mm.

[0124] The circuit board via-filling method provided in this application utilizes a high-pressure environment of 1.55-25MPa combined with a vacuum of 10-100Pa to push the filling material through the capillary resistance of the connecting hole 130 using the pressure difference. This effectively wets small-diameter holes, preventing void defects in the initial filling stage. Furthermore, the design employs a 2-3MPa gradient pressure and a lower vacuum level to ensure sufficient filling of large-diameter holes while controlling the filling rate through pressure decay to prevent material overflow from small holes due to excessive compression. This staged pressure control mechanism ensures that all holes reach the preset filling height and optimizes resin flow characteristics through dynamic matching of vacuum level, ultimately achieving a dual improvement in hole filling density and surface smoothness.

[0125] Figure 6 A flowchart illustrating the circuit board via plugging method provided in this application embodiment. Figure 5 ,like Figure 6 As shown, the embodiments of this application provide a detailed description of the grinding process based on the above embodiments, including:

[0126] S601. Perform the first grinding process to grind the circuit board for the first time.

[0127] In this embodiment, the abrasive material for the first grinding process is abrasive belt.

[0128] In some examples, during the first grinding process, abrasive belts are used as the abrasive material. Their coarse-grained structure rapidly removes the protruding filler material from the surface of the circuit board 100, effectively cutting away 0.05-0.1mm resin burrs that may form after the initial filling. During belt grinding, the equipment reciprocates at a linear speed of 0.5mm / s, utilizing the micro-cutting action of the silicon carbide particles on the belt surface to preferentially remove the cured resin accumulated around the holes, while avoiding excessive wear on the filler inside the holes.

[0129] S602. Perform the second polishing process to polish the circuit board a second time.

[0130] In this embodiment, the grinding material for the second grinding process is a ceramic brush.

[0131] In some examples, the second polishing process switches to ceramic brush polishing, utilizing the composite structure of its rigid bristles and flexible substrate to perform fine processing deep into the 0.2mm micropore opening area. When the ceramic brush rotates at 300 rpm, the bristle tips generate micro-vibrations, which can remove resin residue adhering to the pore walls without damaging the already cured insulating / conductive structure inside the pore. This step focuses on addressing the 5-10μm-level micro-protrusions that may remain after belt polishing. The pore roughness is monitored in real time using a spectral confocal sensor, and the process automatically terminates when the roughness drops to 0.4μm.

[0132] S603. Perform the third polishing process to polish the circuit board for the third time.

[0133] In this embodiment, the grinding material for the third grinding process is non-woven fabric.

[0134] In some examples, during the third polishing process, a non-woven abrasive material is used, utilizing its three-dimensional mesh structure to carry alumina abrasive grains for final polishing of the circuit board 100 surface. When the non-woven fabric rotates at a high speed of 500 rpm, the abrasive grains create uniform scratch tracks on the board surface, gradually eliminating micro-textures generated in previous processes, ultimately achieving a surface roughness of less than 0.2 μm. Particularly for conductive plug areas, the flexible nature of the non-woven fabric avoids scratching the silver paste filler, ensuring that the chamfer at the orifice is controlled within 5 μm, providing a flat base for subsequent component mounting.

[0135] The circuit board via-filling method provided in this application firstly removes excess filler material from the board surface quickly through abrasive belt grinding, significantly improving processing efficiency. Its coarse-grain design effectively prevents resin residue from clogging the micropore openings. Next, a ceramic brush is used for secondary grinding, utilizing rigid bristles to penetrate deep into the pores and remove minute residues, ensuring precise alignment between the end face of the filling structure inside the hole and the board surface. Finally, a non-woven fabric polishing process reduces the surface roughness of the circuit board 100 to a mirror level, eliminating processing marks generated by previous processes and avoiding damage to the conductive plug structure, ultimately achieving perfect coplanarity between the filling hole and the board surface.

[0136] Figure 7 This is a cross-sectional view of the circuit board provided in an embodiment of this application, as shown below. Figure 7 As shown, this application embodiment also provides a circuit board 100, which can be manufactured by the circuit board plugging method provided in the above embodiment.

[0137] The surface of the circuit board 100 may be provided with two connecting holes 130, and the diameters of the two connecting holes 130 are different; each connecting hole 130 is provided with a filling structure, wherein the first surface 110 of the circuit board 100 may be the C-side or the S-side of the circuit board 100, and the second surface 120 is the corresponding other side.

[0138] The circuit board 100 provided in this application embodiment, by setting unequal diameter connecting holes 130 on the surface of the circuit board 100 and constructing a differentiated filling structure, not only ensures precise graded control of the multi-hole filling process, but also significantly improves the forming quality of the conductive layer inside the hole. The staged filling strategy ensures the reliability of the preset depth filling of the small-diameter connecting holes 130, while the double-sided collaborative process optimizes the filling uniformity of the large-diameter connecting holes 130, effectively avoiding filling defects caused by hole diameter differences in traditional processes. This structure simplifies the filling process to a single whole-board operation through process integration, greatly shortening the production cycle while ensuring the integrity of the conductive path, and achieving the effects of reducing the cost of hole plugging and improving the quality of hole plugging.

[0139] It should be noted that the numerical values ​​and ranges involved in this application are approximate values. Due to the influence of the manufacturing process, there may be a certain range of errors, which can be considered negligible by those skilled in the art.

[0140] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0141] In the description of this application, it should be understood that the terms “center,” “length,” “width,” “thickness,” “top,” “bottom,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “inner,” “outer,” “axial,” and “circumferential,” etc., used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the indicated position or component must have a specific orientation, or a specific structure and operation, and therefore should not be construed as a limitation of the present invention.

[0142] The devices or elements referred to in the embodiments of this application or implied herein must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of this application. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise precisely specified.

[0143] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0144] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0145] The term "multiple" in this article refers to two or more. The term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Furthermore, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects; in formulas, the character " / " indicates a "division" relationship between the preceding and following related objects.

[0146] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application.

[0147] It is understood that, in the embodiments of this application, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

Claims

1. A method for plugging vias in a circuit board, characterized in that, include: A circuit board is provided having at least two through holes, the diameters of the at least two through holes being unequal; wherein, along the thickness direction of the circuit board, the circuit board has a first surface and a second surface disposed opposite to each other; A first mask is placed on one of the first surface and the second surface of the circuit board; wherein the first mask includes a first opening that exposes the smallest of the at least two connecting holes; Perform the first filling process to fill the preset depth of the connecting hole with the smallest aperture; The first mask is removed, and a second mask is placed on the other of the first surface and the second surface of the circuit board; wherein the second mask has at least two second openings that expose the corresponding connecting holes; A second filling process is performed to fill the at least two connecting holes to form a filling structure in each of the connecting holes.

2. The method according to claim 1, characterized in that, The first filling process, which fills the preset depth of the connecting hole with the smallest aperture, includes: The circuit board is placed in a vacuum plugging machine; The smallest aperture connecting hole is filled from the first surface with a filling material, such that the filling material fills to the preset depth of the smallest aperture connecting hole; The process parameters of the first filling process are determined by the diameter of the smallest connecting hole.

3. The method according to claim 2, characterized in that, The second filling process, which fills the at least two connecting holes, includes: Flip the circuit board so that the second surface faces the filling head of the vacuum plugging machine; In the second filling process of the vacuum plugging machine, filling material is used to fill all the connecting holes from the second surface so that all the connecting holes are at least completely filled. The second filling process is determined by the diameter of all the connecting holes, and the second filling process is calculated based on the compensation system corresponding to all the connecting holes.

4. The method according to any one of claims 1 to 3, characterized in that, If the diameter of the smallest connecting hole is less than or equal to 0.2 mm, then the preset depth is two-thirds of the thickness of the circuit board. If the diameter of the smallest connecting hole is greater than 0.2 mm and less than 0.3 mm, then the preset depth is one-third of the thickness of the circuit board.

5. The method according to claim 4, characterized in that, The at least two connecting holes include a first connecting hole and a second connecting hole; the diameter of the first connecting hole is 0.2 mm, and the diameter of the second connecting hole is 0.5 mm.

6. The method according to claim 5, characterized in that, The process parameters for the first filling process include at least one of the following: The plugging pressure is greater than 1.5 MPa; The vacuum level of the vacuum plugging machine is 10 Pa to 100 Pa; The vacuum dwell time is 10 to 30 seconds.

7. The method according to claim 3, characterized in that, In the second filling process of the vacuum plugging machine, filling material is used to fill all the connecting holes from the second surface, including: The first sub-filling process is performed to fill a portion of the depth of all the connecting holes; the pressure of the first sub-filling process is 1.55 MPa to 25 MPa, and the vacuum degree of the first sub-filling process is 10 Pa to 100 Pa. A second sub-filling process is performed to fill the remaining depth of all the connecting holes so that all the connecting holes are at least fully filled; the pressure of the second sub-filling process is 2 MPa to 3 MPa, the vacuum degree of the second sub-filling process is 10 Pa to 100 Pa, and the vacuum degree of the second sub-filling process is less than the vacuum degree of the first sub-filling process.

8. The method according to any one of claims 1 to 3, characterized in that, After performing the second filling process to fill the at least two connecting holes, the process further includes: A baking process is performed to solidify the filling material that has been filled into the at least two interconnected holes; A grinding process is used to remove the filler material on the circuit board, leaving the filler material in the connecting hole so that one end of the filler material in the connecting hole is flush with the first surface and the other end of the filler material in the connecting hole is flush with the second surface.

9. The method according to claim 8, characterized in that, The grinding process for removing filler material from the circuit board includes: The circuit board is first polished using a first polishing process; wherein the polishing material in the first polishing process is abrasive belt. A second grinding process is performed to grind the circuit board a second time; wherein, the grinding material in the second grinding process is a ceramic brush; A third polishing process is performed to polish the circuit board for the third time; wherein the polishing material of the third polishing process is non-woven fabric.

10. A circuit board, characterized in that, The circuit board via plugging method as described in any one of claims 1 to 9 is used; The circuit board has two connecting holes with different diameters; each connecting hole is filled with a filling structure.

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