Printed circuit board and manufacturing process of printed circuit board

Abstract

The application discloses a printed circuit board and a manufacturing process of the printed circuit board. The printed circuit board comprises a board main body, a graphene material and a sealing element. The board main body has a first surface layer and a second surface layer oppositely distributed along a first direction, the first surface layer has a first area suitable for connecting a power device, the second surface layer has a second area suitable for connecting a heat sink, the board main body is provided with a via hole penetrating through the first area and the second area along the first direction, and the inner wall of the via hole is covered by a copper-based material. The graphene material fills the via hole, and the sealing element seals the opening of the via hole along the axial direction of the via hole. The first surface layer comprises a first copper foil, the second surface layer comprises a second copper foil, and the sealing element is electrically connected with the first copper foil and the second copper foil. The application can improve the heat dissipation capacity and the electric conduction capacity of the printed circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular to a printed circuit board and a manufacturing process of the printed circuit board. Background Art

[0002] As electronic devices develop towards higher performance and higher integration, thermal management issues for PCBs (printed circuit boards) are becoming increasingly prominent. Traditional PCB heat dissipation relies primarily on surface heat sinks or metal substrates, but this approach has significant limitations.

[0003] First, traditional PCBs have a single heat dissipation path. They typically utilize copper-clad / epoxy glass cloth or phenolic resin glass cloth substrates. While these materials offer excellent electrical and processing properties, they suffer from poor heat dissipation. Heat generated by high-power devices (such as CPUs, GPUs, and power MOSFETs) is primarily conducted through the PCB surface, where it is dissipated to the surrounding environment via surface heat sinks or metal substrates. This single heat dissipation path hinders rapid heat dissipation, resulting in inefficient heat dissipation.

[0004] Secondly, heat conduction issues within high-power devices exacerbate the formation of localized high-temperature hotspots. As the performance of electronic devices continues to improve, the heat generated by high-power devices has increased significantly. When this heat is transferred to the PCB surface through a flat surface, the limited thermal conductivity of the PCB material prevents even heat distribution, leading to the formation of localized high-temperature hotspots. These localized high temperatures not only degrade device performance but can also lead to overheating and failure, impacting device reliability and service life. Summary of the Invention

[0005] The main purpose of the present invention is to provide a printed circuit board and a manufacturing process of the printed circuit board, which can improve the heat dissipation capacity and electrical conductivity of the printed circuit board.

[0006] To achieve the above objectives, some embodiments of the present invention provide a printed circuit board, wherein one side of the printed circuit board is suitable for connecting to a power device and the other side is suitable for connecting to a heat sink, and the printed circuit board includes:

[0007] The plate body has a first surface layer and a second surface layer that are relatively distributed along a first direction, the first surface layer having a first area suitable for connecting to a power device, the second surface layer having a second area suitable for connecting to a heat sink, and the plate body having a via hole that passes through the first area and the second area along the first direction, wherein the inner wall of the via hole is covered with a copper-based material;

[0008] Graphene material, filling the vias;

[0009] A sealing member, sealing the opening of the via hole along the axial direction of the via hole;

[0010] The first surface layer includes a first copper foil, the second surface layer includes a second copper foil, and the sealing member electrically connects the first copper foil and the second copper foil.

[0011] In some embodiments, the board body includes a fiberglass board, and the fiberglass board is sandwiched between the first copper foil and the second copper foil; or,

[0012] The board body includes multiple fiberglass boards and multiple third copper foils, which are alternately distributed along the first direction, and the first copper foil is connected to the fiberglass board on the side facing the second copper foil, and the second copper foil is connected to the fiberglass board on the side facing the first copper foil.

[0013] In some embodiments, the graphene material includes graphene and a conductive additive, wherein the graphene accounts for at least 80% of the mass of the graphene material.

[0014] In some embodiments, the range of the via hole diameter D is: 0.1 mm ≤ D ≤ 0.5 mm;

[0015] The thickness d1 of the copper-based material covering the inner wall of the via hole is in the range of: 20µm≤d1≤25µm;

[0016] Along the axial direction of the through hole, the thickness d2 of the sealing member satisfies the following range: 20µm≤d2≤25µm.

[0017] An embodiment of a second aspect of the present invention provides a manufacturing process for a printed circuit board, which is applied to any of the above-mentioned printed circuit boards, and the manufacturing process includes:

[0018] The electric field induces the graphene sheets to align along the axis of the via;

[0019] Graphene material is injected into the vias.

[0020] In some embodiments, the step of injecting the graphene material into the via hole includes:

[0021] Vacuum assisted imprinting of vias into graphene material.

[0022] In some embodiments, the step of vacuum assisted imprinting vias and injecting graphene material comprises:

[0023] The graphene material is injected into the vias using a vacuum dispenser and / or a screen printer.

[0024] In some embodiments, the ambient pressure p1 during vacuum-assisted imprinting is in the range of 15 MPa≤p1≤20 MPa.

[0025] In some embodiments, after injecting the graphene material into the vias and performing vacuum-assisted molding, the process further includes:

[0026] The graphene material is pre-cured at a first preset temperature t1, wherein the range of the first preset temperature t1 is: 75° C. ≤ t1 ≤ 85° C.;

[0027] The graphene material is cured using a second preset temperature t2, and the range of the second preset temperature t2 is: 150°C≤t2≤200°C.

[0028] In some embodiments, the manufacturing process includes:

[0029] The electric field induces the graphene sheets to align along the axis of the via;

[0030] A mixture of graphene and a conductive additive after the electric field-induced graphene sheets are aligned along the axis of the via is injected into the via.

[0031] According to the above embodiments, the beneficial effects of the present invention are:

[0032] The printed circuit board of the present invention includes a plate body, a graphene material, and a seal. The plate body has a first surface layer and a second surface layer arranged relative to each other along a first direction. The first surface layer has a first region suitable for connecting to a power device, and the second surface layer has a second region suitable for connecting to a heat sink. The plate body also has a via hole extending along the first direction through the first and second regions. The inner wall of the via hole is covered with a copper-based material. This copper-based material covering the inner wall of the via hole not only enhances the conductivity of the via hole, but also improves its mechanical strength and prevents the material filled in the via hole from penetrating into the plate body and affecting the printed circuit board.

[0033] Graphene material fills the vias. Due to its properties, graphene effectively improves thermal conductivity, facilitating heat transfer from the first surface layer to the second surface layer. A sealant is positioned at the via opening, sealing the via along its axis. The first surface layer comprises a first copper foil, and the second surface layer comprises a second copper foil. The sealant electrically connects the first and second copper foils, ensuring electrical continuity.

[0034] The printed circuit board of this application significantly improves thermal and electrical conductivity by optimizing via design and material combination. Specifically, the board body is provided with multiple vias, which are spaced apart and filled with graphene material that exhibits excellent thermal and electrical conductivity. By covering the inner walls of the vias with a copper-based material and combining them with electroplated copper caps, the graphene material forms a tight electrical connection with other structures of the board body (such as the first copper foil, the second copper foil, etc.), thereby constructing a three-dimensional network that is interwoven vertically and horizontally.

[0035] This three-dimensional network not only ensures efficient current transmission but also achieves uniform heat distribution through graphene's high thermal conductivity. For example, when a PCB is connected to a power device on one side and a heat sink on the other, heat generated in one part of the PCB can be rapidly transferred to other areas through this three-dimensional network and quickly released through the heat sink. Simultaneously, the cooling effect of the heat sink can also be quickly distributed to all parts of the PCB through this network, achieving efficient thermal management.

[0036] In summary, this application constructs a three-dimensional network with excellent electrical conductivity and thermal conductivity through the synergistic effect of graphene materials, copper-based materials and seals, which significantly improves the heat dissipation capacity and overall performance of the printed circuit board, and is particularly suitable for application scenarios of high power density and high-frequency circuits.

[0037] Furthermore, the inventors considered that when filling vias with graphene material, the graphene sheets tend to agglomerate during the filling process, resulting in uneven filling of the vias and the formation of voids or uneven filling. A small mistake can make a big difference, and the presence of voids and uneven filling can seriously affect electrical and thermal conductivity. Furthermore, the graphene material has a weak bond with the inner wall of the via, making it difficult to ensure long-term electrical continuity and mechanical stability.

[0038] In order to solve the above technical problems, the present application adopts the following means to fill the graphene material into the via hole and make it cooperate with other structures of the printed circuit board: the graphene sheets are arranged along the axis direction of the via hole through the electric field to ensure the uniform distribution and efficient filling of the graphene material in the via hole, and the arrangement of the graphene sheets along the axis direction of the via hole can maximize its conductivity; vacuum-assisted imprinting technology is used to inject the graphene material into the via hole to ensure a high-pressure environment during the filling process, avoid the agglomeration of the graphene sheets, and improve the filling efficiency and quality; the inner wall of the via hole is covered with a copper-based material to enhance the conductivity and mechanical strength of the via hole, while ensuring the close bonding between the graphene material and the inner wall of the via hole; a seal is set at the via hole opening to ensure the electrical continuity of the graphene material and prevent oxidation and corrosion. Through the above structural design and manufacturing process, the printed circuit board of the present application can efficiently complete the filling of the graphene material and ensure its synergy with other structures of the printed circuit board, thereby significantly improving the conductivity and thermal conductivity, and extending the service life of the printed circuit board.

[0039] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0041] Figure 1 Schematic diagram of the structure of a printed circuit board in one embodiment of the present invention;

[0042] Figure 2 is a schematic structural diagram of a printed circuit board in another embodiment of the present invention;

[0043] Figure 3 FIG1 is a flow chart of a process for manufacturing a printed circuit board according to an embodiment of the present invention;

[0044] Figure 4 FIG. 4 is a flow chart of a process for manufacturing a printed circuit board in another embodiment of the present invention.

[0045] Description of Figure Numbers:

[0046] Plate body 100; first surface layer 110; second surface layer 120; third copper foil 130; fiberglass board 140; via 150;

[0047] Seal 200;

[0048] Copper-based materials 300;

[0049] Graphene materials 400;

[0050] Power device 500;

[0051] Radiator 600;

[0052] Thermal conductive silicone sheet 700.

[0053] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0055] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0056] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or", "and / or" or "and / or" appear in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0057] Refer to the following Figures 1 to 4 , to describe the printed circuit board and the manufacturing process of the printed circuit board of this application. Figure 1 and Figure 2 In some embodiments, a printed circuit board includes a board body 100, a graphene material 400, and a sealant 200. The board body 100 has a first surface layer 110 and a second surface layer 120 that are relatively distributed along a first direction. The first surface layer 110 has a first area suitable for connecting to a power device 500, and the second surface layer 120 has a second area suitable for connecting to a heat sink 600. The board body 100 is also provided with a via 150 that passes through the first area and the second area along the first direction. The inner wall of the via 150 is covered with a copper-based material 300. The copper-based material 300 covering the inner wall of the via 150 not only enhances the conductivity of the via 150, but also improves its mechanical strength, and can prevent the material filled in the via 150 from penetrating into the interior of the board body 100 and affecting the printed circuit board.

[0058] Graphene material 400 fills the interior of via 150. Due to the properties of graphene, this material can effectively improve thermal conductivity, facilitating heat transfer from the first surface layer 110 to the second surface layer 120. A sealant 200 is positioned at the opening of via 150, sealing the via 150 along its axis. The first surface layer 110 comprises a first copper foil, and the second surface layer 120 comprises a second copper foil. The sealant 200 electrically connects the first and second copper foils, ensuring electrical continuity.

[0059] In principle, by filling the via 150 with graphene material 400 and covering the inner wall with copper-based material 300, current can efficiently flow from the first surface layer 110 to the second surface layer 120. The graphene material 400 also facilitates rapid heat conduction. Furthermore, by adding specific components to the graphene material 400, the graphene material 400 itself becomes conductive. Combined with graphene's inherent high thermal conductivity, the graphene material 400 filled in the via 150 is both electrically and thermally conductive. The perimeter wall of the graphene material 400 in the via 150 is connected to the printed circuit board via the copper-based material 300, and the two ends of the graphene material 400 in the via 150 are connected to the printed circuit board via the seal 200. As a result, the graphene material 400 in the via 150 can be deeply integrated with the other structures of the printed circuit board and impart its own high thermal conductivity and high electrical conductivity to the system. Therefore, the design of this application enables the printed circuit board to support high-power density applications while effectively dissipating heat and extending its service life. Due to the excellent electrical and thermal conductivity of the graphene material 400, the entire circuit board can significantly reduce operating temperature while maintaining high performance, improving overall reliability.

[0060] The following uses a specific embodiment as an example to describe the beneficial effects of the present application in more detail. For example, in a specific embodiment, the printed circuit board of the present application significantly improves thermal conductivity and electrical conductivity by optimizing the design and material combination of the via 150. Specifically, a plurality of vias 150 are provided on the plate body 100. These vias 150 are evenly distributed in a spaced array, and the graphene material 400 filled in the via 150 has excellent thermal conductivity and electrical conductivity. By covering the inner wall of the via 150 with a copper-based material 300 and combining it with an electroplated copper cap, the graphene material 400 forms a close electrical connection with other structures of the plate body 100 (such as the first copper foil, the second copper foil, the third copper foil 130, etc.), thereby constructing a three-dimensional network that is crisscrossed.

[0061] This three-dimensional network not only ensures efficient current transmission but also achieves uniform heat distribution through graphene's high thermal conductivity. For example, when a power device 500 is connected to one side of a printed circuit board and a heat sink 600 is connected to the other side, heat generated in one part of the board can be quickly transferred to other areas through this three-dimensional network and quickly released through heat sink 600. Simultaneously, the cooling effect of heat sink 600 can also be quickly distributed to all parts of the board through this network, achieving efficient thermal management.

[0062] In summary, this application constructs a three-dimensional network with excellent electrical conductivity and thermal conductivity through the synergistic effect of graphene material 400 and copper-based material 300, which significantly improves the heat dissipation capacity and overall performance of the printed circuit board, and is particularly suitable for application scenarios of high power density and high-frequency circuits.

[0063] Furthermore, the inventors considered that when graphene material 400 is filled into via 150, the graphene sheet structure tends to agglomerate during the filling process, resulting in uneven filling of via 150 and the formation of voids or uneven filling. A small mistake can lead to a huge difference, and the presence of voids and uneven filling can seriously affect electrical and thermal conductivity. Furthermore, the weak bonding between graphene material 400 and the inner wall of via 150 makes it difficult to ensure long-term electrical continuity and mechanical stability.

[0064] In order to solve the above technical problems, the present application adopts the following means to fill the graphene material 400 into the via 150 and make it cooperate with other structures of the printed circuit board: through the electric field to induce the graphene sheets to arrange along the axis direction of the via 150, ensuring the uniform distribution and efficient filling of the graphene material 400 in the via 150; using vacuum assisted imprinting technology to inject the graphene material 400 into the via 150, ensuring a high-pressure environment during the filling process, avoiding the agglomeration of the graphene sheets, and improving the filling efficiency and quality; covering the inner wall of the via 150 with a copper-based material 300 to enhance the conductivity and mechanical strength of the via 150, while ensuring the close bonding between the graphene material 400 and the inner wall of the via 150; and setting a seal 200 at the opening of the via 150 to ensure the electrical continuity of the graphene material 400 and prevent oxidation and corrosion. Through the above-mentioned structural design and manufacturing process, the printed circuit board of the present application can efficiently complete the filling of the graphene material 400 and ensure its synergy with other structures of the printed circuit board, thereby significantly improving the electrical conductivity and thermal conductivity, and extending the service life of the printed circuit board.

[0065] In some embodiments, the seal 200 is an electroplated copper cap, which is formed by performing an electroplating process at the opening of the via 150. First, the inner wall of the via 150 is covered with a copper-based material 300, and then a conductive material (such as graphene or copper paste) is filled from the opening of the via 150. A layer of copper is then plated on the surface of the filling material through an electroplating process to form a flat cap. This structure allows the opening of the via 150 to be completely covered with copper, forming a seamless sealing layer. The electroplated copper cap can provide excellent conductive properties, ensuring efficient transmission of current in the via 150 while reducing contact resistance. In addition, the electroplated copper cap can make the surface of the via 150 smooth, avoiding tin leakage or cold soldering problems caused by the uneven opening of the via 150. Furthermore, the electroplated copper cap is not only combined with the graphene material 400, but also combined with the first copper foil and the second copper foil. It can be understood that the electroplated copper cap becomes an intermediate carrier that associates the graphene material 400 with the first copper foil and the second copper foil. Since the electroplated copper cap itself has good thermal conductivity and electrical conductivity, the first copper foil and the second copper foil are easily affected by the graphite material. Such a design can further improve the thermal conduction efficiency of the via 150 and help dissipate heat.

[0066] It will be appreciated that in some embodiments, to enhance electrical connection reliability, a thin layer of gold plating can be added to each end of via 150. This not only improves contact resistance with the copper foil but also prevents oxidation. Furthermore, a certain proportion of silver nanoparticles can be mixed into graphene material 400 to improve its conductivity. Such a combination is particularly suitable for high-frequency circuit design because it can reduce signal loss and improve transmission efficiency.

[0067] Reference Figure 1 and Figure 2 In some embodiments, the board body 100 includes a fiberglass board 140, which is sandwiched between a first copper foil and a second copper foil to form a solid base structure. In some embodiments, the board body 100 includes multiple fiberglass boards 140 and multiple third copper foils 130. The multiple fiberglass boards 140 and the multiple third copper foils 130 are alternately distributed along a first direction, and the first copper foil is connected to the fiberglass board 140 on the side facing the second copper foil, and the second copper foil is connected to the fiberglass board 140 on the side facing the first copper foil. By alternating the stacking of fiberglass boards 140 and third copper foils 130, a more solid composite structure with excellent electrical performance is formed. This structure can not only withstand higher mechanical stress, but also provide greater flexibility for complex circuit layouts. This structure can adapt to higher-density wiring requirements while ensuring good heat dissipation performance, making it suitable for application scenarios with extremely high stability requirements, such as high-performance computing and servers.

[0068] It will be appreciated that in some embodiments, the board body 100 may utilize a ceramic material as the substrate, replacing the traditional fiberglass board 140, to further enhance thermal conductivity. In this case, the vias 150 remain covered by the copper-based material 300 and filled with the graphene material 400. The ceramic substrate provides improved insulation and high-temperature resistance, making it suitable for more demanding operating environments. For example, for electronic devices that must operate under extreme conditions, such as circuit boards in aerospace applications, the ceramic substrate and graphene-filled vias 150 can provide superior stability and reliability.

[0069] It is understood that in some embodiments, in addition to the fiberglass board 140, a polyimide (PI) film can also be used to replace part of the fiberglass board 140, especially in applications where flexibility is required. PI film has excellent flexibility and temperature resistance, making it very suitable for use in electronic products that need to bend or fold, such as wearable devices or flexible displays. By introducing PI film, the circuit board can gain additional flexibility while maintaining its original performance, broadening its application range. Furthermore, in some embodiments, to further improve electrical isolation performance, a thin layer of polytetrafluoroethylene (PTFE) film can be added between the fiberglass board 140 and the copper foil. PTFE film not only has excellent dielectric properties, but also effectively prevents the intrusion of moisture and other impurities, thereby improving the long-term stability of the circuit board. This improvement is particularly suitable for electronic devices used outdoors or in humid environments, such as wireless communication base stations or ocean monitoring systems.

[0070] Reference Figure 1 and Figure 2 In some embodiments, graphene material 400 is composed of graphene and a conductive additive, with graphene comprising at least 80% of the graphene material 400 by mass. Graphene itself possesses excellent electrical and thermal conductivity, while the conductive additive further enhances the overall conductive properties of the graphene material 400. This combination not only improves the efficiency of current flow through the via 150 but also optimizes the heat transfer path from the first surface layer 110 to the second surface layer 120. Specifically, the graphene sheets are designed to align along the axis of the via 150 to maximize their conductive properties. This oriented alignment is achieved by applying an external electric field, ensuring that the graphene sheets form an efficient current path. The conductive additive is dispersed between the graphene sheets, increasing the contact area between the materials and thereby reducing the overall electrical resistance. By combining the conductive additive with high-purity graphene, the material's conductive properties can be significantly enhanced while maintaining good mechanical strength. This design allows the printed circuit board to withstand higher currents while reducing energy losses, improving overall system efficiency.

[0071] It is understood that in some embodiments, to further enhance the conductivity of graphene material 400, copper or silver nanoparticles may be used as conductive additives. Copper and silver nanoparticles have extremely high conductivity, and due to their small size, they can significantly increase the number of conductive pathways within the material without significantly increasing the volume. For example, when 5% (by mass) of silver nanoparticles is added to graphene material 400, its overall conductivity can be improved by approximately 20%, which is particularly beneficial for applications that require handling high currents.

[0072] It is understood that in some embodiments, in addition to silver and copper nanoparticles, carbon nanotubes (CNTs) may also be considered. CNTs possess excellent mechanical strength and electrical conductivity, and mixing them with graphene can further enhance the performance of the composite material. Specifically, a 9:1 mass ratio of graphene to CNTs not only improves the material's conductivity but also enhances its mechanical stability, preventing cracking or failure caused by repeated thermal expansion and contraction.

[0073] In some embodiments, to design graphene material 400 with excellent conductivity, the lattice structure can be optimized to reduce grain boundary defects, thereby improving conductivity. For example, by controlling the precipitation temperature to adjust the graphene nucleation density, chemical vapor deposition (CVD) can be used to produce high-quality, uniform, and tunable single-layer polycrystalline graphene films with grain sizes ranging from 200 nanometers to 1 micron. The grain boundaries of such films are perfectly aligned, reducing their negative impact on conductivity and significantly improving the conductivity of the graphene. Specifically, the CVD method utilizes high temperature and a high vacuum environment to cause a carbon-containing gas to chemically react on the substrate surface to form graphene. By controlling the precipitation temperature and nucleation density, grain boundary defects can be reduced and the lattice structure optimized. Grain boundary defects scatter electrons and increase resistance, while reducing them can increase electron mobility, thereby improving conductivity. The following systematically illustrates the chemical vapor deposition (CVD) method used in this application, for example, by precisely controlling the precipitation temperature and the flow rate of the carbon source gas to adjust the graphene nucleation density. Under high temperature, a carbon source gas (such as methane) decomposes on the substrate surface, where carbon atoms nucleate and gradually grow into graphene sheets. By optimizing growth conditions (such as temperature, pressure, and gas flow rate), high-quality, single-layer polycrystalline graphene films with uniform and tunable grain sizes ranging from 200 nanometers to 1 micron can be produced. These films exhibit perfectly aligned grain boundaries, minimizing their negative impact on electrical conductivity and significantly improving graphene's electrical conductivity.

[0074] Reference Figure 1 and Figure 2In some embodiments, the diameter D of via 150 satisfies the range of 0.1 mm ≤ D ≤ 0.5 mm, for example, D is 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm. This range ensures sufficient mechanical strength while facilitating manufacturing. In some embodiments, the thickness d1 of the copper-based material 300 covering the inner wall of via 150 ranges from 20 µm ≤ d1 ≤ 25 µm, for example, d1 is 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, or 25 µm. This not only enhances the conductivity of via 150 but also provides necessary mechanical support. Along the axis of via 150, the thickness d2 of sealant 200 ranges from 20 µm ≤ d2 ≤ 25 µm, for example, d2 is 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, or 25 µm, ensuring the continuity and reliability of the electrical connection. By precisely controlling the via 150 diameter, the copper-based material 300 thickness, and the seal 200 thickness, the current transmission path can be optimized and resistive losses reduced. Furthermore, proper sizing helps improve heat dissipation efficiency, as a smaller via 150 diameter reduces the distance heat must travel, while the appropriate copper-based material 300 thickness ensures excellent thermal conductivity. This sophisticated design enables the printed circuit board to excel in high-power density applications while maintaining a lower operating temperature and extending its service life.

[0075] It is understood that in some embodiments, for applications requiring particularly high heat dissipation performance, a multi-layer copper foil structure can be used instead of a single copper-based material 300 coating. For example, a thin nickel layer (approximately 5µm thick) is deposited on the inner wall of via 150, followed by a thicker copper layer (approximately 30µm thick). The nickel layer not only provides additional corrosion protection but also promotes better adhesion of the copper layer to the surface of via 150, thereby improving overall heat conduction efficiency and long-term stability.

[0076] Reference Figures 1 to 4 , the embodiment of the second aspect of the present application proposes a manufacturing process for a printed circuit board. Figure 3 In some embodiments, a process for manufacturing a printed circuit board includes:

[0077] S101: The electric field induces the graphene sheets to align along the axis of the via hole 150;

[0078] S103 : injecting the graphene material 400 into the via hole 150 .

[0079] First, an external electric field is applied to align the graphene sheets along the axis of the via 150. The electric field aligns the graphene nanosheets, creating an efficient current channel. This process leverages graphene's high conductivity, ensuring efficient current transfer from the first surface layer 110 to the second surface layer 120. Electric field induction requires a high-precision programmable DC power supply to apply a DC electric field (1-10 kV / cm) to the graphene dispersion, leveraging electrophoretic or dielectric forces to align the graphene sheets. This ensures that the graphene sheets are aligned along the axis of the via 150, maximizing current transmission efficiency and minimizing resistive losses.

[0080] Next, the electric-field-induced aligned graphene material 400 is injected into via 150. This graphene filling not only enhances the conductivity of via 150 but also improves thermal conductivity, facilitating heat dissipation. For example, a vacuum dispenser can be used to inject the graphene slurry into via 150, ensuring a high-pressure environment during the filling process, preventing graphene flakes from agglomerating and improving filling efficiency and quality. Electric field induction (10-50 kHz) aligns the flakes along the hole axis, increasing thermal conductivity to 950 W / m·K (in the Z direction). This design enables the printed circuit board to handle higher-power devices while maintaining a lower operating temperature, extending its service life.

[0081] In some embodiments, the step of injecting the graphene material 400 into the via hole 150 includes:

[0082] The vacuum assisted imprinted vias 150 are injected with the graphene material 400 .

[0083] Due to the vacuum environment, gas molecules in the air are effectively removed, thus preventing the formation of bubbles. At the same time, the graphene material 400 can be tightly packed under pressure, reducing the possibility of voids. This method not only improves filling quality but also enhances the electrical and thermal conductivity of the via 150.

[0084] It will be appreciated that in some embodiments, to further optimize the filling effect, ultrasonic vibrations can be introduced during the vacuum-assisted imprinting process. Ultrasonic vibrations can promote better dispersion of the graphene material 400 and help expel any tiny bubbles that may be present. For example, when the ultrasonic frequency is set to 40 kHz, the graphene material 400 can be filled more densely within the via 150, thereby significantly improving electrical and thermal conductivity.

[0085] It is understood that in some embodiments, to accommodate more complex manufacturing requirements, a multi-step injection molding process can be employed. First, a vacuum-assisted stamping process is used to initially fill the vias 150, followed by secondary or even tertiary filling in subsequent steps to ensure that every detail is adequately filled. For example, after the initial filling, a pre-curing process can be performed, followed by a secondary filling and final curing. While complex, this method can significantly improve filling quality and consistency, making it particularly suitable for applications with extremely high electrical and thermal conductivity requirements.

[0086] In some embodiments, the step of injecting the graphene material 400 into the vacuum-assisted imprinted via 150 includes:

[0087] The graphene material 400 is injected into the via hole 150 using a vacuum dispensing machine and / or a screen printing machine.

[0088] In some embodiments, the step of vacuum-assisted imprinting vias 150 with graphene material 400 includes injecting the graphene material 400 into the vias 150 using a vacuum dispenser. The specific steps are as follows: First, the printed circuit board is placed in a vacuum chamber of the vacuum dispenser. The chamber door is closed and the chamber is evacuated to reduce air resistance and ensure that the graphene material 400 can smoothly fill the vias 150. Next, the graphene material 400 is mixed with an appropriate amount of conductive additive to form a uniform graphene slurry to improve its conductivity and filling performance. The graphene slurry is then loaded into the barrel of the vacuum dispenser, and the appropriate pressure (e.g., 15-20 MPa) and temperature are set to ensure slurry fluidity. Through the precise control of the vacuum dispenser, the graphene slurry is evenly injected into the vias 150. The negative pressure of the vacuum environment ensures that the slurry tightly fills the vias 150, avoiding the formation of voids and bubbles. For example, suppose a 0.3mm via 150 needs to be filled. The specific steps are: Place the printed circuit board (PCB) into the vacuum chamber of a vacuum dispenser, close the chamber door, and activate the vacuum function to bring the chamber pressure to a rated value (e.g., -0.1 MPa). Graphene and silver nanoparticles are mixed in a specific ratio to form a graphene slurry with excellent conductivity. The graphene slurry is then loaded into a dispenser, and the dispensing pressure is set to 15-20 MPa and the temperature to room temperature to ensure slurry fluidity. The dispenser is activated, and the graphene slurry is evenly injected into the via 150 through precise control. The dispenser's motion trajectory can be set to dots, lines, circles, S-shaped patterns, or squares to accommodate different via 150 distributions. Finally, the PCB is placed in an oven for pre-curing at a preset temperature (e.g., 75-85°C), followed by a final cure at 150-200°C to ensure the stability and conductivity of the graphene material 400. Through the above operations, the graphene material 400 can be efficiently filled into the via hole 150 and ensured to be evenly distributed and densely arranged, thereby significantly improving the electrical conductivity and thermal conductivity of the printed circuit board.

[0089] In some embodiments, the operating steps for imprinting graphene using a screen printer are as follows: first, select a suitable screen material (such as a stainless steel screen) and design the pattern of the screen according to the size and distribution of the vias 150; then, mix the graphene material 400 with a conductive additive to form a slurry suitable for screen printing; then, install the screen on the screen printer, and adjust the pressure and movement trajectory of the scraper to ensure that the slurry can be evenly transferred through the screen into the vias 150; finally, in a vacuum environment, the graphene slurry is evenly imprinted into the vias 150 through the scraper action of the screen printer. The stability and pressure control of the scraper are key to ensuring the filling quality. Taking filling a 0.3mm via 150 as an example, the specific steps include: designing a screen pattern that matches the size of via 150, ensuring that the screen's aperture is slightly larger than the diameter of via 150; mixing graphene and silver nanoparticles in a specific ratio to form a graphene slurry with excellent conductivity; securing the screen to a screen printer, adjusting the squeegee pressure to 15-20 MPa, and imprinting the slurry into via 150 with a uniform linear motion; after imprinting, placing the printed circuit board in an oven for pre-curing at a preset temperature (e.g., 75-85°C), followed by a final cure at 150-200°C to ensure the stability and conductivity of the graphene material 400. Through these steps, the graphene material 400 can be efficiently filled into via 150, ensuring its uniform distribution and dense arrangement, significantly improving the electrical and thermal conductivity of the printed circuit board.

[0090] Through the above operations, the graphene material 400 can be efficiently filled into the via hole 150 and ensured to be evenly distributed and densely arranged, thereby significantly improving the electrical conductivity and thermal conductivity of the printed circuit board.

[0091] In some embodiments, the ambient pressure p1 during vacuum-assisted imprinting is in the range of 15 MPa ≤ p1 ≤ 20 MPa. For example, p1 is 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, or 20 MPa. When the ambient pressure p1 is too high, the graphene material 400 may fill too quickly, resulting in bubbles and uneven filling, affecting filling quality. Furthermore, excessive pressure may damage the equipment, increasing wear and maintenance costs, and may disrupt the structure of the graphene sheet, affecting its electrical and thermal conductivity. Conversely, when the ambient pressure p1 is too low, the graphene material 400 may not completely fill the via 150, affecting electrical and thermal conductivity. Excessively low pressure also reduces filling efficiency, increases production time, and may cause the graphene material 400 to form voids and bubbles in the via 150, affecting the performance of the final product. Therefore, selecting an appropriate ambient pressure p1 is crucial to ensuring uniform filling of the graphene material 400 and high-quality production. By precisely controlling the pressure within the range of 15 MPa to 20 MPa, the above problems can be effectively avoided, ensuring uniform distribution and dense arrangement of the graphene material 400 in the vias 150 , thereby significantly improving the electrical conductivity and thermal conductivity of the printed circuit board.

[0092] It is understood that in some embodiments, the filling effect can be optimized by adjusting different vacuum-assisted imprinting parameters. For example, a lower ambient pressure (such as 15 MPa) can be selected for initial filling, and then the ambient pressure can be increased to 20 MPa for secondary filling. This phased operation method not only effectively eliminates bubbles but also ensures that every detail is fully filled, making it suitable for applications with strict requirements on filling quality and conductivity. In addition, different stages of the filling process can be combined with different pre-curing and final curing steps to further improve the filling effect and material properties.

[0093] In some embodiments, after injecting the graphene material 400 into the via 150 and performing vacuum assisted molding, the following steps are further included:

[0094] The graphene material 400 is pre-cured at a first preset temperature t1, wherein the range of the first preset temperature t1 is: 75° C. ≤ t1 ≤ 85° C.;

[0095] The graphene material 400 is cured at a second preset temperature t2, and the range of the second preset temperature t2 is: 150°C≤t2≤200°C.

[0096] First, graphene material 400 is injected into via hole 150 by vacuum-assisted pressing. After the injection is completed, graphene material 400 is pre-solidified using a first preset temperature t1, where t1 is in the range of 75°C ≤ t1 ≤ 85°C, for example, t1 is 75°C, 76°C, 77°C, 78°C, 79°C, or 80°C. The pre-solidification process helps to preliminarily fix the position of graphene material 400, reducing its movement or loss in subsequent processing. Next, a second preset temperature t2 is used for final solidification, where t2 is in the range of 150°C to 200°C, for example, t2 is 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C. This step can further enhance the structural stability of graphene material 400, ensuring excellent electrical conductivity and mechanical strength. In principle, the pre-solidification and final solidification processes gradually increase the temperature, allowing the molecular chains inside graphene material 400 to arrange in an orderly manner, thereby improving the overall performance of the material. This phased solidification method not only effectively improves the filling quality, but also significantly enhances the electrical conductivity and thermal conduction efficiency of via hole 150.

[0097] It can be understood that, in some embodiments, in order to optimize the effect of pre-solidification and final solidification, a cooling step can be introduced between each solidification step. For example, after pre-solidification is completed, the temperature is lowered to room temperature (about 25°C) before final solidification. This method helps to reduce stress concentration and avoid material deformation or cracking caused by sudden temperature changes, thereby improving the reliability and durability of the final product.

[0098] It can be understood that, in some embodiments, the solidification effect can also be optimized by adjusting the temperature curve of pre-solidification and final solidification. For example, during pre-solidification, a gradient heating method can be used, first increasing from 75°C to 80°C, maintaining for a period of time, and then increasing to 85°C; while during final solidification, it can gradually increase from 150°C to 200°C. This method can better control the molecular rearrangement process inside graphene material 400, thereby achieving more uniform and denser filling effect, especially suitable for applications with high requirements on electrical conductivity and mechanical strength.

[0099] In some embodiments, the manufacturing process of the printed circuit board comprises:

[0100] The graphene sheets induced by the electric field are arranged along the axis direction of via hole 150;

[0101] The mixture of graphene and conductive additives after arranging the graphene sheets induced by the electric field along the axis direction of via hole 150 is injected into via hole 150.

[0102] First, an electric field is used to induce the alignment of pure graphene sheets along the axis of via 150. The aligned pure graphene is then mixed with a conductive additive to form graphene material 400, a slurry. This slurry is then filled into via 150. The electric field induction initially aligns the graphene sheets, laying the foundation for efficient electrical and thermal conductivity for subsequent filling. Subsequently, mixing with the conductive additive further enhances the material's electrical conductivity. The slurry is easy to handle and can evenly and densely fill via 150, eliminating voids and air bubbles and improving filling quality. This sequence ensures a tight bond between the graphene material 400 and the inner wall of via 150, enhancing bonding and ensuring long-term electrical continuity and mechanical stability. Furthermore, the slurry's fluidity and adaptability improve filling efficiency, reduce production time, and enhance overall production efficiency. It can also accommodate vias 150 of varying sizes and shapes, increasing process flexibility. This process sequence significantly improves the performance of printed circuit boards, enabling them to better meet the application requirements of high power density and high frequency circuits.

[0103] It is understood that in some embodiments, to further enhance the alignment of the graphene sheets, a magnetic field can be introduced during the electric field induction process. For example, applying a weak magnetic field perpendicular to the electric field can encourage the graphene sheets to align more closely, thereby further improving electrical and thermal conductivity. Specifically, the magnetic field strength can be set to 0.1T to 0.3T, which helps enhance the packing density and consistency of the graphene material 400.

[0104] It is understood that in some embodiments, it is also possible to consider surface treating the graphene material 400 before electric field induction. For example, plasma treatment technology is used to modify the graphene surface to improve its compatibility and dispersibility with conductive additives. Specifically, the plasma treatment time can be set to 5 minutes to 10 minutes, and the power can be set to 100W to 200W. This method can not only improve the dispersibility of the graphene material 400, but also enhance the adhesion between it and the wall of the via 150, thereby further improving the filling quality and conductive performance. In addition, this surface treatment technology is also suitable for other applications that require high conductivity and good mechanical properties.

[0105] The printed circuit board manufacturing process of the present invention significantly improves thermal conductivity and electrical conductivity by optimizing the design and material combination of the via 150. Figures 1 to 4 , the manufacturing process of the printed circuit board of the present invention is systematically described:

[0106] S201: Prepare the plate body 100. The plate body 100 has a first surface layer 110 and a second surface layer 120 arranged opposite each other along a first direction. The first surface layer 110 has a first region suitable for connecting to the power device 500, and the second surface layer 120 has a second region suitable for connecting to the heat sink 600. The plate body 100 is provided with a via 150 extending through the first and second regions along the first direction. The inner wall of the via 150 is covered with a copper-based material 300 with a thickness ranging from 20µm ≤ d1 ≤ 25µm.

[0107] S202: Preparation of graphene material 400. Graphene material 400 includes graphene and a conductive additive, with graphene comprising at least 80% of the mass of graphene material 400. Electric field induction (10-50 kHz) aligns the graphene sheets along the axis of via 150, forming a highly efficient electrical and thermal conduction channel.

[0108] S203: Vacuum-assisted imprinting. Graphene slurry (a mixture of nano-dispersed graphene and conductive additives such as silver powder or copper powder) is injected into via 150. Vacuum-assisted imprinting is performed using a vacuum dispenser and / or screen printer. The ambient pressure range is 15 MPa ≤ p1 ≤ 20 MPa, ensuring a fill rate > 95%.

[0109] S204: Curing treatment. A two-step curing method is used: pre-curing at 75℃~85℃ to eliminate stress, and then gradient curing at 150℃~200℃ to enhance interface bonding. After curing, thermal and electrical conductive paths are formed.

[0110] S205: Multi-layer interconnect structure design. Dense graphene-filled vias 150 are placed on the pads beneath key heat-generating components (such as the CPU and power chips), with a spacing of 0.5-1mm. These vias form a thermal path with the PCB's top, inner, and bottom copper layers, as well as the external heat sink 600, reducing thermal resistance. A thermally conductive silicone sheet 700 can be placed above the heat sink 600 to optimize heat transfer between the heat sink 600 and the printed circuit board.

[0111] S206: Installing a sealant 200. Install a sealant 200 (e.g., an electroplated copper cap) at the opening of the via 150 to ensure electrical continuity of the graphene material 400 and prevent oxidation and corrosion. Grind the surface of the sealant 200 to make it flush with the surface of the plate body 100.

[0112] Through the above process, the printed circuit board of the present invention forms a three-dimensional network that interweaves vertical and horizontal lines, ensuring efficient current transmission and uniform heat distribution. It has a Z-axis thermal conductivity of ≥950 W / m·K, a thermal resistance of ≤0.12 K / W, a thermal cycle life of <8% thermal conductivity degradation after 500 cycles at -40°C to 125°C, and a flexural strength of ≥80 MPa. This design significantly improves the heat dissipation capacity and overall performance of the printed circuit board, making it particularly suitable for applications in high-power devices (such as CPUs, GPUs, and power MOSFETs) and high-frequency circuits.

[0113] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A printed circuit board, wherein one side of the printed circuit board is suitable for connecting a power device and the other side is suitable for connecting a heat sink, characterized in that: include: The plate body has a first surface layer and a second surface layer that are relatively distributed along a first direction, the first surface layer having a first area suitable for connecting to the power device, the second surface layer having a second area suitable for connecting to the heat sink, the plate body having a via hole that passes through the first area and the second area along the first direction, and the inner wall of the via hole is covered with a copper-based material; Graphene material filling the via hole; a sealing member, sealing the opening of the via hole along the axial direction of the via hole; The first surface layer includes a first copper foil, the second surface layer includes a second copper foil, the sealant electrically connects the first copper foil and the second copper foil, and the graphene sheets are arranged along the axis direction of the via hole through electric field induction, and the graphene material is injected into the via hole using vacuum assisted imprinting technology.

2. The printed circuit board according to claim 1, wherein: The plate body includes a fiberglass board, and the fiberglass board is sandwiched between the first copper foil and the second copper foil; or, The plate body includes multiple glass fiber boards and multiple third copper foils, and the multiple glass fiber boards and multiple third copper foils are alternately distributed along the first direction, and the first copper foil is connected to the glass fiber board on the side facing the second copper foil, and the second copper foil is connected to the glass fiber board on the side facing the first copper foil.

3. The printed circuit board according to claim 1, wherein: The graphene material includes graphene and a conductive additive, and the graphene accounts for at least 80% of the mass of the graphene material.

4. The printed circuit board according to claim 1, wherein: The range of the via hole diameter D is: 0.1mm≤D≤0.5mm; The range of the thickness d1 of the copper-based material covering the inner wall of the via hole is: 20µm≤d1≤25µm; Along the axial direction of the through hole, the thickness d2 of the sealing member satisfies the following range: 20µm≤d2≤25µm.

5. A process for manufacturing a printed circuit board, applied to the printed circuit board according to any one of claims 1 to 4, characterized in that: The manufacturing process of the printed circuit board includes: The electric field induces the graphene sheets to align along the axis of the via hole; The graphene material is injected into the via hole.

6. The process for manufacturing a printed circuit board according to claim 5, wherein: The step of injecting the graphene material into the via hole comprises: The via holes are vacuum-assisted printed to inject the graphene material.

7. The process for manufacturing a printed circuit board according to claim 6, wherein: The step of vacuum-assisted imprinting the via holes and injecting the graphene material comprises: The graphene material is injected into the via hole using a vacuum dispensing machine and / or a screen printing machine.

8. The process for manufacturing a printed circuit board according to claim 6, wherein: The range of the ambient pressure p1 during the vacuum-assisted imprinting is: 15 MPa≤p1≤20 MPa.

9. The process for manufacturing a printed circuit board according to claim 5, wherein: After the step of injecting the graphene material into the via hole and using vacuum assisted molding, the method further includes: Pre-curing the graphene material at a first preset temperature t1, wherein the range of the first preset temperature t1 is: 75° C. ≤ t1 ≤ 85° C.; The graphene material is cured at a second preset temperature t2, wherein the range of the second preset temperature t2 is: 150°C≤t2≤200°C.

10. The process for manufacturing a printed circuit board according to claim 5, wherein: include: The electric field induces the graphene sheets to align along the axis of the via hole; A mixture of graphene and a conductive additive after the electric field induces the graphene sheets to be aligned along the axis direction of the via hole is injected into the via hole.

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