Printed circuit board and manufacturing process of printed circuit board

Abstract

The invention discloses a printed circuit board and a manufacturing process of the printed circuit board. The printed circuit board comprises a board body, a graphene material and a sealing piece. The plate body is provided with a first surface layer and a second surface layer which are oppositely distributed in the first direction, the first surface layer is provided with a first area suitable for being connected with a power device, the second surface layer is provided with a second area suitable for being connected with a radiator, and the plate body is provided with a via hole penetrating through the first area and the second area in the first direction. The inner wall of the via hole is covered by a copper-based material. The via hole is filled with the graphene material, and the sealing piece seals an opening of the via hole in the axis direction of the via hole. Wherein 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 heat dissipation capability and the conductivity of the printed circuit board can be improved.

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 high performance and high integration, the thermal management problem of PCB (printed circuit board) becomes increasingly prominent. Traditional PCB heat dissipation mainly relies on surface heat sinks or metal substrates, which has obvious limitations.

[0003] First, the heat dissipation path of traditional PCBs is single. Traditional PCBs usually use copper-clad / epoxy glass cloth substrates or phenolic resin glass cloth substrates. Although these materials have excellent electrical properties and processing performance, they have poor heat dissipation. The heat generated by high-power devices (such as CPU, GPU, power MOSFET) is mainly conducted to the surface of the PCB through the plane, and then dissipated to the surrounding environment through the surface heat sink or metal substrate. This single heat dissipation path prevents the heat from spreading quickly and has low heat dissipation efficiency.

[0004] Secondly, the heat conduction problem of high-power devices exacerbates the formation of local high-temperature hot spots. As the performance of electronic devices continues to improve, the heat generated by high-power devices has increased significantly. When this heat is conducted to the surface of the PCB through the plane, due to the limited thermal conductivity of the PCB material, the heat cannot be evenly distributed, and high-temperature hot spots are easily formed in local areas. Local high temperature will not only reduce the performance of the device, but may also cause the device to overheat and fail, affecting the reliability and service life of the equipment. 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 object, some embodiments of the present invention provide a printed circuit board, one side of the printed circuit board is suitable for connecting a power device, and the other side of the printed circuit board is suitable for connecting a heat sink, and the printed circuit board includes: 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 has a first area, the first area is suitable for connecting a power device, the second surface layer has a second area, the second area is suitable for connecting a heat sink, and the plate body is provided with a via hole that penetrates 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; Graphene material, filling vias; 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, and the sealing member electrically connects the first copper foil and the second copper foil.

[0007] 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, 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 one side of the second copper foil, and the second copper foil is connected to the fiberglass board on one side of the first copper foil.

[0008] In some embodiments, the graphene material includes graphene and a conductive additive, and the graphene accounts for at least 80% of the mass of the graphene material.

[0009] In some embodiments, the range of the via hole diameter D is: 0.1 mm ≤ D ≤ 0.5 mm; 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 via hole, the thickness d2 of the sealing member satisfies the following range: 20µm≤d2≤25µm.

[0010] An embodiment of the 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: The electric field induces the graphene sheets to align along the axis of the via; Graphene material is injected into the vias.

[0011] In some embodiments, the step of injecting the graphene material into the via hole includes: Vacuum assisted imprinting of vias into graphene material.

[0012] In some embodiments, the step of vacuum assisted imprinting vias to inject graphene material comprises: The graphene material is injected into the vias using a vacuum dispenser and / or a screen printer.

[0013] In some embodiments, the range of the ambient pressure p1 during vacuum assisted imprinting is: 15 MPa≤p1≤20 MPa.

[0014] In some embodiments, after the step of injecting the graphene material into the via hole and using vacuum assisted molding, the process further includes: 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.; The graphene material is cured at a second preset temperature t2, and the range of the second preset temperature t2 is: 150°C≤t2≤200°C.

[0015] In some embodiments, the manufacturing process includes: The electric field induces the graphene sheets to align along the axis of the via; A mixture of graphene and a conductive additive after the electric field-induced graphene sheets are arranged along the axis direction of the via is injected into the via.

[0016] According to the above embodiments, the beneficial effects of the present invention are: The printed circuit board of the present invention comprises a plate body, a graphene material and a sealing member. The plate body has a first surface layer and a second surface layer which are relatively distributed along a first direction. The first surface layer has a first area suitable for connecting a power device, and the second surface layer has a second area suitable for connecting a heat sink. The plate body is also provided with a via hole which penetrates 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. The 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 can prevent the material filled in the via hole from penetrating into the plate body and affecting the printed circuit board.

[0017] The graphene material is filled inside the via hole. Due to the characteristics of graphene, the material can effectively improve the heat conduction efficiency and help transfer heat from the first surface layer to the second surface layer. The seal is arranged at the opening of the via hole to seal the via hole along the axial direction. The first surface layer includes a first copper foil, and the second surface layer includes a second copper foil. The seal electrically connects the first copper foil and the second copper foil to ensure electrical continuity.

[0018] The printed circuit board of the present application significantly improves thermal conductivity and electrical conductivity by optimizing the via design and material combination. Specifically, a plurality of vias are provided on the main body of the board, and these vias are spaced apart, and the graphene material filled in the vias has excellent thermal conductivity and electrical conductivity. By covering the inner wall of the via with a copper-based material and combining it with an electroplated copper cap, the graphene material forms a close electrical connection with other structures of the main body of the board (such as the first copper foil, the second copper foil, etc.), thereby constructing a three-dimensional network that is crisscrossed.

[0019] This three-dimensional network not only ensures efficient transmission of current, but also achieves uniform heat distribution through the high thermal conductivity of graphene. For example, when a power device is connected to one side of a printed circuit board and a heat sink is connected to the other side, the heat generated in one part of the printed circuit board can be quickly transferred to other areas through the three-dimensional network and quickly released through the heat sink. At the same time, the cooling effect of the heat sink can also quickly affect various parts of the printed circuit board through the network, thereby achieving efficient thermal management.

[0020] 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.

[0021] Furthermore, the inventors considered that when the vias are filled with graphene materials, the graphene sheet structure is easy to agglomerate during the filling process, resulting in the inability to uniformly fill the vias, and it is easy to have gaps or uneven filling. A small mistake can make a big difference. The appearance of gaps and uneven filling will seriously affect the electrical and thermal conductivity. In addition, the bonding force between the graphene material and the inner wall of the via is weak, making it difficult to ensure long-term electrical continuity and mechanical stability.

[0022] 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 by electric field induction 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 combination of the graphene material and the inner wall of the via hole; a seal is set at the opening of the via hole 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 can extend the service life of the printed circuit board.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0025] Figure 1 It is a schematic diagram of the structure of a printed circuit board in one embodiment of the present invention; Figure 2 It is a schematic structural diagram of a printed circuit board in another embodiment of the present invention; Figure 3 The present invention is a flowchart of a process for manufacturing a printed circuit board according to an embodiment of the present invention; Figure 4 The present invention is a flowchart of a process for manufacturing a printed circuit board in another embodiment of the present invention.

[0026] Description of Figure Numbers: Plate body 100; first surface layer 110; second surface layer 120; third copper foil 130; glass fiber board 140; via 150; Seal 200; Copper-based materials 300; Graphene materials 400; Power device 500; Radiator 600; Thermally conductive silicone sheet 700.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] 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 in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0030] 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 used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or", "and / or" or "and / or" appears 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 that satisfies both A and B. 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 the field to implement. When the combination of technical solutions is 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.

[0031] Refer to the following Figures 1 to 4 , to describe the printed circuit board and the manufacturing process of the printed circuit board of the present application. Figure 1 and Figure 2In some embodiments, the printed circuit board includes a plate body 100, a graphene material 400, and a seal 200. The plate 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 a power device 500, and the second surface layer 120 has a second area suitable for connecting a heat sink 600. The plate body 100 is also provided with a via 150 that penetrates the first area and the second area along the first direction, and the inner wall of the via 150 is covered by 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 plate body 100 and affecting the printed circuit board.

[0032] The graphene material 400 is filled inside the via hole 150. Due to the characteristics of graphene, the material can effectively improve the heat conduction efficiency and help transfer heat from the first surface layer 110 to the second surface layer 120. The seal 200 is arranged at the opening of the via hole 150 and seals the via hole 150 along the axial direction. The first surface layer 110 includes a first copper foil, the second surface layer 120 includes a second copper foil, and the seal 200 electrically connects the first copper foil and the second copper foil to ensure electrical continuity.

[0033] In principle, by filling the via hole 150 with the graphene material 400 and covering the inner wall with the copper-based material 300, the current can efficiently flow from the first surface layer 110 to the second surface layer 120, and the graphene material 400 helps to quickly conduct heat. In addition, by adding specific components to the graphene material 400, the graphene material 400 itself can be conductive, and combined with the high thermal conductivity of graphene itself, the graphene material 400 filled in the via hole 150 can conduct both electricity and heat. The peripheral wall of the graphene material 400 in the via 150 is connected to the printed circuit board through 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 through the seal 200, so that the graphene material 400 in the via 150 can be deeply combined with other structures of the printed circuit board, and its own high thermal conductivity and high electrical conductivity are given to this system. Therefore, the design of this application enables the printed circuit board to support high power density applications and effectively dissipate heat to extend the service life. Due to the excellent electrical conductivity and thermal conductivity of the graphene material 400, the entire circuit board can significantly reduce the operating temperature and improve the overall reliability while maintaining high efficiency.

[0034] The following uses a specific implementation as an example to more specifically describe the beneficial effects of the present application. For example, in a specific implementation, the printed circuit board of the present application significantly improves thermal conductivity and electrical conductivity by optimizing the via 150 design and material combination. Specifically, a plurality of vias 150 are provided on the board body 100, and 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 with an electroplated copper cap, the graphene material 400 forms a close electrical connection with other structures of the board 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.

[0035] This three-dimensional network not only ensures efficient transmission of current, but also achieves uniform heat distribution through the high thermal conductivity of graphene. For example, when the power device 500 is connected to one side of the printed circuit board and the heat sink 600 is connected to the other side, the heat generated in a certain part of the circuit board can be quickly transferred to other areas through the three-dimensional network and quickly released through the heat sink 600. At the same time, the cooling effect of the heat sink 600 can also quickly affect various parts of the circuit board through the network, thereby achieving efficient thermal management.

[0036] In summary, the present 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.

[0037] Furthermore, the inventors considered that when the via hole 150 is filled with the graphene material 400, the graphene sheet structure is easy to agglomerate during the filling process, resulting in the inability to uniformly fill the via hole 150, and it is easy to have gaps or uneven filling. A small mistake can make a big difference. The appearance of gaps and uneven filling will seriously affect the electrical conductivity and thermal conductivity. In addition, the bonding force between the graphene material 400 and the inner wall of the via hole 150 is weak, 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 400 into the via 150 and make it coordinate with other structures of the printed circuit board: inducing the graphene sheets to be arranged along the axis direction of the via 150 through an electric field to ensure 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 to ensure a high-pressure environment during the filling process, avoid agglomeration of the graphene sheets, and improve filling efficiency and quality; the inner wall of the via 150 is covered 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 a seal 200 is provided 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.

[0039] 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, and then a layer of copper is 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 to form a seamless sealing layer. The electroplated copper cap can provide excellent conductive properties, ensure efficient transmission of current in the via 150, and reduce 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.

[0040] It is understood that in some embodiments, in order to enhance the reliability of the electrical connection, a thin gold plating layer can be added to both ends of the via 150, which can not only improve the contact resistance with the copper foil, but also prevent oxidation. In addition, the graphene material 400 can also be mixed with a certain proportion of silver nanoparticles to improve its conductivity. Such combinations are particularly suitable for high-frequency circuit design because they can reduce signal loss and improve transmission efficiency.

[0041] Reference Figure 1and Figure 2 In some embodiments, the board body 100 includes a fiberglass board 140, and the fiberglass board 140 is sandwiched between the first copper foil and the second copper foil to form a solid basic structure. In some embodiments, the board body 100 includes a plurality of fiberglass boards 140 and a plurality of third copper foils 130, and the plurality of fiberglass boards 140 and the plurality of third copper foils 130 are alternately distributed along the first direction, and the first copper foil is connected to the fiberglass board 140 on one side of the second copper foil, and the second copper foil is connected to the fiberglass board 140 on one side of the first copper foil. By alternately stacking the fiberglass boards 140 and the third copper foil 130, a more solid composite structure with excellent electrical properties is formed. This structure can not only withstand higher mechanical stress, but also provide greater flexibility for complex circuit layout. This structure can adapt to higher density wiring requirements while ensuring good heat dissipation performance, and is suitable for application scenarios with extremely high stability requirements such as high-performance computing and servers.

[0042] It is understood that in some embodiments, the board body 100 may use a ceramic material as a substrate instead of the traditional fiberglass board 140 to further improve the thermal conductivity. In this case, the via 150 is still covered by the copper-based material 300 and filled with the graphene material 400. The ceramic substrate provides better insulation and high temperature resistance and is suitable for more demanding working environments. For example, for electronic devices that need to work under extreme conditions, such as circuit boards in aerospace applications, the ceramic substrate and graphene-filled via 150 can provide excellent stability and reliability.

[0043] 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 situations where flexibility is required. The PI film has excellent flexibility and temperature resistance, and is very suitable for use in electronic products that need to be bent or folded, such as wearable devices or flexible displays. By introducing the PI film, the circuit board can gain additional flexibility while maintaining its original performance, broadening its application range. Further, in some embodiments, in order to further improve the electrical isolation performance, a thin layer of polytetrafluoroethylene (PTFE) film can be added between the fiberglass board 140 and the copper foil. The 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 in outdoor or humid environments, such as wireless communication base stations or marine monitoring systems.

[0044] Reference Figure 1 and Figure 2In some embodiments, the graphene material 400 is composed of graphene and a conductive additive, wherein the graphene accounts for at least 80% of the mass of the graphene material 400. Graphene itself has excellent electrical and thermal conductivity, and the conductive additive further enhances the overall conductive properties of the graphene material 400. This combination not only improves the efficiency of current passing 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 sheet is designed to be arranged along the axis direction of the via 150 to maximize its conductive properties. This directional arrangement is achieved by inducing the application of an external electric field, ensuring that the graphene sheet can form an efficient current channel. The conductive additive is dispersed between the graphene, increasing the contact area between the materials, thereby reducing the overall resistance. By combining the conductive additive with high-purity graphene, the conductive properties of the material can be significantly enhanced while maintaining good mechanical strength. This design allows the printed circuit board to withstand higher currents while reducing energy losses, thereby improving the efficiency of the entire system.

[0045] It is understandable that in some embodiments, in order to further improve the conductivity of the graphene material 400, copper and silver nanoparticles can be selected as conductive additives. Copper and silver nanoparticles have extremely high conductivity, and due to their small size, the number of conductive paths inside the material can be greatly increased without significantly increasing the volume. For example, when 5% (mass fraction) of silver nanoparticles are added to the graphene material 400, its overall conductivity can be improved by about 20%, which is particularly beneficial for application scenarios that need to handle large currents.

[0046] It is understood that in some embodiments, in addition to silver and copper nanoparticles, carbon nanotubes (CNTs) may also be added. Carbon nanotubes have excellent mechanical strength and electrical conductivity, and mixing them with graphene can further improve the performance of the composite material. Specifically, when graphene and carbon nanotubes are mixed in a mass ratio of 9:1, not only can the conductivity of the material be improved, but also its mechanical stability can be enhanced to prevent cracking or failure of the material caused by repeated thermal expansion and contraction.

[0047] In some embodiments, in order to design a graphene material 400 with good conductivity, the grain boundary defects can be reduced by optimizing the lattice structure, thereby improving the conductivity. For example, by using a chemical vapor deposition (CVD) method, the crystal nucleus density of graphene is adjusted by controlling the precipitation temperature, and a high-quality single-layer polycrystalline graphene film with a uniform and adjustable grain size in the range of 200 nanometers to 1 micron can be prepared. The grain boundaries of this film are perfectly aligned, which reduces the negative impact of the grain boundaries on the conductivity, thereby significantly improving the conductivity of graphene. Specifically, the CVD method uses a high temperature and high vacuum environment to cause a carbon-containing gas to react chemically on the surface of the substrate to form graphene. By controlling the precipitation temperature and the nucleation density, the grain boundary defects can be reduced and the lattice structure can be optimized. Grain boundary defects scatter electrons and increase resistance, while reducing grain boundary defects can increase electron mobility, thereby improving conductivity. The following system exemplifies 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, the nucleation density of graphene is adjusted. Under high temperature, carbon source gas (such as methane) decomposes on the substrate surface, carbon atoms nucleate on the substrate 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 adjustable grain sizes in the range of 200 nanometers to 1 micron can be prepared. The grain boundaries of this film are perfectly aligned, reducing the negative impact of grain boundaries on conductivity, thereby significantly improving the conductivity of graphene.

[0048] Reference Figure 1 and Figure 2In some embodiments, the aperture D of the via 150 satisfies the range of 0.1mm≤D≤0.5mm, for example, D is 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, which can ensure sufficient mechanical strength and facilitate processing and manufacturing. In some embodiments, the thickness d1 of the copper-based material 300 covering the inner wall of the via 150 is in the range of 20µm≤d1≤25µm, for example, d1 is 20µm, 21µm, 22µm, 23µm, 24µm, 25µm, which not only enhances the conductivity of the via 150, but also provides necessary mechanical support. Along the axial direction of the via 150, the thickness d2 of the seal 200 satisfies the range of 20µm≤d2≤25µm, for example, d2 is 20µm, 21µm, 22µm, 23µm, 24µm, 25µm, which ensures the continuity and reliability of the electrical connection. By precisely controlling the aperture of the via 150, the thickness of the copper-based material 300, and the thickness of the seal 200, the current transmission path can be optimized and the resistance loss can be reduced. In addition, the reasonable size design also helps to improve the heat dissipation efficiency, because the smaller diameter of the via 150 reduces the distance of heat conduction, and the appropriate thickness of the copper-based material 300 ensures good thermal conductivity. This sophisticated design enables the printed circuit board to perform well in high power density applications while maintaining a low operating temperature and extending the service life.

[0049] It is understood that in some embodiments, for applications that require particular emphasis on 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 (thickness of about 5µm) is sequentially deposited on the inner wall of the via 150, and then a thicker copper layer (thickness of about 30µm) is covered. The nickel layer not only provides additional corrosion protection, but also promotes better adhesion of the copper layer to the surface of the via 150, thereby improving the overall heat conduction efficiency and long-term stability.

[0050] Reference Figures 1 to 4 The second embodiment of the present application provides a manufacturing process for a printed circuit board. Figure 3 In some embodiments, a process for manufacturing a printed circuit board includes: S101: The electric field induces the graphene sheets to be arranged along the axis direction of the via hole 150; S103 : injecting the graphene material 400 into the via hole 150 .

[0051] First, by applying an external electric field, the graphene sheets are arranged along the axis direction of the via 150. The action of the electric field causes the graphene nanosheets to be oriented under the action of the electric field, thereby forming an efficient current channel. This process takes advantage of the high conductivity of graphene to ensure that the current can be efficiently transferred from the first surface layer 110 to the second surface layer 120. Electric field induction requires the use of a high-precision programmable DC power supply to apply a DC electric field (1-10 kV / cm) to the graphene dispersion, and use electrophoretic force or dielectric force to align the graphene sheets. In this way, it can be ensured that the graphene sheets are arranged along the axis direction in the via 150, thereby maximizing the current transmission efficiency and reducing resistance loss.

[0052] Secondly, the graphene material 400 arranged by electric field induction is injected into the via 150. Graphene filling not only enhances the conductivity of the via 150, but also improves the thermal conduction efficiency and helps to dissipate heat. For example, a vacuum dispenser can be used to inject graphene slurry into the via 150 to ensure a high-pressure environment during the filling process, avoid agglomeration of graphene sheets, and improve filling efficiency and quality. The sheets are oriented along the hole axis through electric field induction (10~50 kHz), and the thermal conductivity is increased to 950 W / m·K (Z direction). This design enables the printed circuit board to handle higher power devices and maintain a lower operating temperature, extending the service life.

[0053] In some embodiments, the step of injecting the graphene material 400 into the via hole 150 includes: The vacuum assisted imprinted vias 150 are injected with graphene material 400 .

[0054] Due to the existence of the vacuum environment, the gas molecules in the air are effectively excluded, thereby avoiding the formation of bubbles. At the same time, the graphene material 400 can be closely arranged under pressure, reducing the possibility of voids. This method not only improves the filling quality, but also enhances the electrical conductivity and thermal conductivity of the via 150.

[0055] It is understood that in some embodiments, in order to further optimize the filling effect, ultrasonic vibration can be introduced during the vacuum assisted imprinting process. Ultrasonic vibration can promote better dispersion of the graphene material 400 and help to expel any tiny bubbles that may exist. For example, when the ultrasonic frequency is set to 40kHz, the filling of the graphene material 400 in the via 150 can be made denser, thereby significantly improving electrical conductivity and thermal conductivity.

[0056] It is understood that in some embodiments, in order to adapt to more complex manufacturing requirements, a multi-step injection molding method can also be used. First, the via 150 is initially filled by vacuum-assisted embossing, and then a second or even third filling is performed in subsequent steps to ensure that every detail is fully filled. For example, after the initial filling, a pre-curing treatment can be performed, followed by a secondary filling and final curing. Although this method is complex, it can greatly improve the filling quality and consistency, and is particularly suitable for applications with extremely high requirements for electrical and thermal conductivity.

[0057] In some embodiments, the step of injecting the graphene material 400 into the vacuum assisted imprint via 150 includes: The graphene material 400 is injected into the via hole 150 by using a vacuum dispensing machine and / or a screen printing machine.

[0058] In some embodiments, the step of injecting the graphene material 400 into the via 150 by vacuum-assisted imprinting includes injecting the graphene material 400 into the via 150 by using a vacuum dispenser. The specific operation is as follows: First, place the printed circuit board in a vacuum box of the vacuum dispenser, close the box door and evacuate the box to reduce air resistance and ensure that the graphene material 400 can smoothly fill the via 150. Next, mix the graphene material 400 with an appropriate amount of conductive additive to form a uniform graphene slurry to improve its conductivity and filling performance. Then, load the graphene slurry into the barrel of the vacuum dispenser, and set a suitable pressure (such as 15-20MPa) and temperature to ensure the fluidity of the slurry. Through the precise control of the vacuum dispenser, the graphene slurry is uniformly injected into the via 150, and the negative pressure of the vacuum environment is used to ensure that the slurry can tightly fill the via 150 to avoid the generation of gaps and bubbles. For example, assuming that a via 150 with a size of 0.3 mm needs to be filled, the specific operation is as follows: put the printed circuit board into the vacuum box of the vacuum dispenser, close the box door and start the vacuum function to make the air pressure in the box reach the rated value (such as -0.1MPa); mix graphene and silver nanoparticles in a certain proportion to form a graphene slurry with excellent conductive properties; load the graphene slurry into the barrel, set the dispensing pressure to 15-20MPa, and the temperature to room temperature to ensure the fluidity of the slurry; start the dispenser, and through precise control, evenly inject the graphene slurry into the via 150. The motion trajectory of the dispenser can be set to points, straight lines, circles, S-shaped, squares, etc. to adapt to different distributions of vias 150. Finally, place the printed circuit board in an oven, pre-cure it at a preset temperature (such as 75-85°C), and then perform final curing 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.

[0059] In some embodiments, the operating steps of 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 via 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 to the via 150; finally, in a vacuum environment, the graphene slurry is evenly imprinted into the via 150 through the scraper action of the screen printer, and the stability and pressure control of the scraper are the key to ensuring the filling quality. Taking filling a via hole 150 with a size of 0.3 mm as an example, the specific operations include: designing a screen pattern matching the size of the via hole 150, ensuring that the aperture of the screen is slightly larger than the diameter of the via hole 150; mixing graphene and silver nanoparticles in a certain proportion to form a graphene slurry with excellent conductive properties; fixing the screen on a screen printer, adjusting the pressure of the scraper to 15-20 MPa, and imprinting the slurry into the via hole 150 with a uniform linear motion; after the imprinting is completed, placing the printed circuit board in an oven, pre-curing at a preset temperature (such as 75-85°C), and then finally curing 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 ensure that it is evenly distributed and densely arranged, thereby significantly improving the conductivity and thermal conductivity of the printed circuit board.

[0060] 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.

[0061] In some embodiments, the range of the environmental pressure p1 during the vacuum-assisted imprinting is: 15MPa≤p1≤20MPa. For example, p1 is 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa. When the environmental pressure p1 is too high, the graphene material 400 may be filled too quickly, bubbles and uneven filling may be generated, and the filling quality may be affected; at the same time, excessive pressure may damage the equipment, increase the wear and maintenance cost of the equipment, and may destroy the structure of the graphene sheet layer, affecting its electrical conductivity and thermal conductivity. On the contrary, when the environmental pressure p1 is too low, the graphene material 400 may not be able to completely fill the via 150, affecting the electrical conductivity and thermal conductivity; too low pressure will also reduce the filling efficiency, increase the production time, and may cause the graphene material 400 to form gaps and bubbles in the via 150, affecting the performance of the final product. Therefore, choosing a suitable environmental pressure p1 is crucial to ensure uniform filling and high-quality production of the graphene material 400. 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 via 150, thereby significantly improving the electrical conductivity and thermal conductivity of the printed circuit board.

[0062] It is understandable that in some embodiments, the filling effect can also be optimized by adjusting different vacuum-assisted imprinting parameters. For example, a lower ambient pressure (such as 15MPa) can be selected for initial filling, and then the ambient pressure can be increased to 20MPa for secondary filling. This phased operation method can not only effectively eliminate bubbles, but also ensure that every detail is fully filled, which is suitable for application scenarios with strict requirements on filling quality and conductivity. In addition, the filling process at different stages can be combined with different pre-curing and final curing steps to further improve the filling effect and material performance.

[0063] In some embodiments, after injecting the graphene material 400 into the via hole 150 and performing vacuum assisted molding, the process further includes: 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.; 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.

[0064] First, the graphene material 400 is injected into the via 150 by vacuum assisted embossing. After the injection is completed, the graphene material 400 is pre-cured using a first preset temperature t1, wherein the range of t1 is 75°C≤t1≤85°C, for example, t1 is 75°C, 76°C, 77°C, 78°C, 79°C, 80°C. The pre-curing process helps to initially fix the position of the graphene material 400 and reduce its movement or loss in subsequent processing. Next, the second preset temperature t2 is used for final curing, and the range of t2 is 150°C to 200°C, for example, t2 is 150°C, 160°C, 170°C, 180°C, 190°C, 200°C. This step can further enhance the structural stability of the graphene material 400 and ensure that it has excellent electrical conductivity and mechanical strength. In principle, the pre-curing and final curing processes enable the molecular chains inside the graphene material 400 to be arranged in an orderly manner by gradually increasing the temperature, thereby improving the performance of the overall material. This staged curing method can not only effectively improve the filling quality, but also significantly enhance the electrical conductivity and thermal conduction efficiency of the via 150 .

[0065] It is understood that in some embodiments, in order to optimize the effects of pre-curing and final curing, a cooling step can be introduced between each curing step. For example, after the pre-curing is completed, the temperature is lowered to room temperature (about 25°C) before final curing. 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.

[0066] It is understandable that in some embodiments, the curing effect can also be optimized by adjusting the temperature curve of pre-curing and final curing. For example, in the pre-curing process, a gradient temperature rise method can be adopted, first from 75°C to 80°C, and then raised to 85°C after a period of time; and in the final curing, it can be gradually raised from 150°C to 200°C. This method can better control the molecular rearrangement process inside the graphene material 400, thereby achieving a more uniform and denser filling effect, which is particularly suitable for application scenarios with high requirements for conductivity and mechanical strength.

[0067] In some embodiments, a process for manufacturing a printed circuit board includes: The electric field induces the graphene sheets to be arranged along the axis direction of the via hole 150; A mixture of graphene and a conductive additive after the electric field induced graphene sheets are arranged along the axis direction of the via hole 150 is injected into the via hole 150 .

[0068] First, the graphene sheets of pure graphene are arranged along the axis direction of the via 150 by electric field induction, and then the arranged graphene pure graphene and conductive additives are mixed to form graphene material 400, which is in the state of slurry. The graphene material 400 in the state of slurry is filled into the via 150. The electric field induction first makes the graphene sheets oriented, laying a foundation for efficient electrical and thermal conductivity for subsequent filling; then it is mixed with the conductive additive to further enhance the conductive properties of the material. The graphene material 400 in the state of slurry is easy to operate, and can fill the via 150 evenly and densely, avoiding voids and bubbles, and improving the filling quality. This sequence ensures the close combination of the graphene material 400 and the inner wall of the via 150, enhances the bonding force, and ensures long-term electrical continuity and mechanical stability. In addition, the fluidity and adaptability of the slurry improve the filling efficiency, reduce the production time, and improve the overall production efficiency. It can also adapt to vias 150 of different sizes and shapes, increasing the flexibility of the process. 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.

[0069] It is understood that in some embodiments, in order to further improve the alignment effect of the graphene sheets, a magnetic field assist may be introduced during the electric field induction process. For example, when a weak magnetic field perpendicular to the electric field direction is applied, the graphene sheets may be arranged more closely, thereby further improving the electrical conductivity and thermal conductivity. Specifically, the magnetic field strength may be set to 0.1T to 0.3T, which helps to enhance the packing density and consistency of the graphene material 400.

[0070] 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, the graphene surface is modified by plasma treatment technology 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 is 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.

[0071] The printed circuit board manufacturing process of the present invention significantly improves thermal conductivity and electrical conductivity by optimizing the via 150 design and material combination. Figures 1 to 4 , the manufacturing process of the printed circuit board of the present invention is systematically described: S201: Prepare the plate body 100. The plate 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 the power device 500, and the second surface layer 120 has a second area suitable for connecting the heat sink 600. The plate body 100 is provided with a via 150 that penetrates the first area and the second area along the first direction. The inner wall of the via 150 is covered by a copper-based material 300, and the thickness range is 20µm≤d1≤25µm.

[0072] S202: Preparation of graphene material 400. Graphene material 400 includes graphene and conductive additives, and graphene accounts for at least 80% of the mass of graphene material 400. The graphene sheets are arranged along the axis direction of via 150 by electric field induction (10-50 kHz), forming an efficient conductive and thermal conductive channel.

[0073] S203: Vacuum assisted imprinting. Inject graphene slurry (nano-dispersed graphene mixed with conductive additives such as silver powder and copper powder) into the via 150. Use a vacuum dispensing machine and / or a screen printer for vacuum assisted imprinting, with an ambient pressure range of 15MPa≤p1≤20MPa, ensuring a filling rate of >95%.

[0074] S204: Curing treatment. A two-step curing method is used, first pre-curing at 75℃~85℃ to eliminate stress, then gradient curing at 150℃~200℃ to enhance interface bonding, and forming a thermal and electrical conductive path after curing.

[0075] S205: Multi-layer interconnection structure design. Dense graphene-filled vias 150 are set on the pads below key heat-generating components (such as CPU and power chips) with a spacing of 0.5-1 mm, and form a thermal path with the PCB surface, internal and bottom copper layers and the external heat sink 600 to reduce thermal resistance. A thermally conductive silicone sheet 700 can be set above the heat sink 600 to optimize heat transfer between the heat sink 600 and the printed circuit board.

[0076] S206: Setting the seal 200. Setting the seal 200 (such as an electroplated copper cap) at the opening of the via 150 to ensure the electrical continuity of the graphene material 400 and prevent oxidation and corrosion. Grinding the surface of the seal 200 to make it flush with the surface of the plate body 100.

[0077] Through the above process, the printed circuit board of the present invention constructs a three-dimensional network that is interwoven vertically and horizontally to ensure efficient current transmission and uniform heat distribution. The Z-direction thermal conductivity is ≥950W / m·K, the thermal resistance is ≤0.12K / W, the thermal cycle life is 500 times -40°C~125°C cycle after thermal conductivity attenuation is <8%, and the bending strength is ≥80MPa. This design significantly improves the heat dissipation capacity and overall performance of the printed circuit board, and is particularly suitable for application scenarios of high-power devices 500 (such as CPU, GPU, power MOSFE) and high-frequency circuits.

[0078] 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 changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A printed circuit board, one side of which is suitable for connecting a power device, and the other side of which 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 has a first area, the first area is suitable for connecting the power device, the second surface layer has a second area, the second area is suitable for connecting the heat sink, the plate body is provided with a via hole that penetrates 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; 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, and the sealing member electrically connects the first copper foil and the second copper foil.

2. The printed circuit board according to claim 1, characterized in that: The board body includes a glass fiber board, and the glass fiber board is sandwiched between the first copper foil and the second copper foil; or, The board body includes a plurality of the glass fiber boards and a plurality of third copper foils, wherein the plurality of the glass fiber boards and the plurality of third copper foils are alternately distributed along the first direction, and the first copper foil is connected to the glass fiber boards on one side toward the second copper foil, and the second copper foil is connected to the glass fiber boards on one side toward the first copper foil.

3. The printed circuit board according to claim 1, characterized in that: 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, characterized in that: 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 covered by the inner wall of the via hole is: 20µm≤d1≤25µm; Along the axial direction of the via 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 comprises: The electric field induces the graphene sheets to be arranged along the axis direction 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, characterized in that: The step of injecting the graphene material into the via hole comprises: The vias are vacuum-assisted printed to inject the graphene material.

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

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

9. The process for manufacturing a printed circuit board according to claim 5, characterized in that: 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 using 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 second preset temperature t2 is in the range of 150°C≤t2≤200°C.

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

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