Composite copper foil structure, preparation method thereof, copper-clad laminate and printed circuit board

文档序号：473529 发布日期：2021-12-31 浏览：72次中文

阅读说明：本技术 复合铜箔结构、其制备方法及覆铜箔层压板和印刷电路板 (Composite copper foil structure, preparation method thereof, copper-clad laminate and printed circuit board ) 是由张齐艳蔡黎高峰于 2021-08-31 设计创作，主要内容包括：本申请公开了一种复合铜箔结构、其制备方法及覆铜箔层压板和印刷电路板。其中,复合铜箔结构包括铜箔芯层和壳层；铜箔芯层具有第一表面和第二表面；壳层至少位于铜箔芯层的第一表面和第二表面；其中,壳层包括N层石墨烯层和M层金属铜层,石墨烯层和金属铜层交替叠层设置,壳层中靠近铜箔芯层的一面为石墨烯层,铜箔芯层的厚度大于壳层中金属铜层的厚度。该复合铜箔结构由金属铜层和石墨烯层交替形成,利用石墨烯和铜的复合效应来提升复合铜箔结构的表层电导率,从而提供一种高电导率的复合铜箔结构。并且,由于仅是在芯层的表面设置有由石墨烯层和金属铜层组成的壳层,而芯层还是采用铜箔,因此成本较低。(The application discloses a composite copper foil structure, a preparation method thereof, a copper-clad laminate and a printed circuit board. The composite copper foil structure comprises a copper foil core layer and a shell layer; the copper foil core layer is provided with a first surface and a second surface; the shell layers are at least positioned on the first surface and the second surface of the copper foil core layer; the shell layer comprises N layers of graphene layers and M layers of metal copper layers, the graphene layers and the metal copper layers are alternately stacked, the side, close to the copper foil core layer, of the shell layer is the graphene layer, and the thickness of the copper foil core layer is larger than that of the metal copper layers in the shell layer. The composite copper foil structure is formed by alternately forming metal copper layers and graphene layers, and the surface conductivity of the composite copper foil structure is improved by utilizing the composite effect of graphene and copper, so that the composite copper foil structure with high conductivity is provided. In addition, the shell layer consisting of the graphene layer and the metal copper layer is only arranged on the surface of the core layer, and the core layer is made of copper foil, so the cost is low.)

1. A composite copper foil structure, comprising:

the copper foil core layer is provided with a first surface and a second surface which are opposite along the thickness direction;

a shell layer at least on the first surface and the second surface of the copper foil core layer;

the shell layer comprises N graphene layers and M metal copper layers, the graphene layers and the metal copper layers are alternately stacked, one surface, close to the copper foil core layer, of the shell layer is the graphene layer, N is an integer larger than 0, M is an integer larger than 0, and M is N or M is N-1;

the thickness of the copper foil core layer is larger than that of the metal copper layer in the shell layer.

2. The composite copper foil structure of claim 1, wherein the copper foil core layer is single-crystallized to induce a preferred orientation of the surface of the copper foil core layer along a (111) crystal plane.

3. The composite copper foil structure of claim 1 or 2, wherein at least one of said M metallic copper layers is single-crystallized, said single-crystallization inducing a surface of said metallic copper layer to preferentially orient along a (111) crystal plane.

4. The composite copper foil structure of any one of claims 1-3, wherein the copper foil core layer has a thickness of 0.5oz to 6 oz.

5. The composite copper foil structure according to any one of claims 1 to 4, wherein the thickness of each of the M metallic copper layers is 0.1 μ M to 40 μ M.

6. The composite copper foil structure of any one of claims 1-5, wherein each of the N graphene layers is between 1 and 10 graphene layers thick.

7. The composite copper foil structure of any one of claims 1-6, wherein the metallic copper layer in the shell layer is formed by physical vapor deposition or electrochemical deposition.

8. A copper clad laminate comprising a dielectric material and the composite copper foil structure of any one of claims 1-7 disposed in a stack.

9. A printed circuit board comprising the copper clad laminate of claim 8, or the composite copper foil structure of any one of claims 1-7.

10. A preparation method of a composite copper foil structure is characterized by comprising the following steps:

providing a copper foil core layer, wherein the copper foil core layer is provided with a first surface and a second surface which are opposite along the thickness direction;

forming shell layers on at least the first surface and the second surface of the copper foil core layer;

the shell layer comprises N graphene layers and M metal copper layers, the graphene layers and the metal copper layers are alternately stacked, the graphene layer is arranged on one side, close to the copper foil core layer, of the shell layer, N is an integer larger than 0, M is an integer larger than 0, and M is N or M is N-1; the thickness of the copper foil core layer is larger than that of the metal copper layer in the shell layer.

11. The method of manufacturing according to claim 10, further comprising, before forming the shell layer on the surface of the copper foil core layer: and carrying out single crystallization treatment on the copper foil core layer, wherein the single crystallization treatment is used for inducing the surface of the copper foil core layer to be preferentially oriented along a (111) crystal plane.

12. The production method according to claim 10 or 11, wherein forming the shell layer on the surface of the copper foil core layer comprises:

13. The method according to claim 12, wherein when the graphene layers and the metallic copper layers are alternately stacked on the surface of the copper foil core layer, at least one of the graphene layers is formed by a thin film transfer method or a chemical vapor deposition method.

14. The method according to claim 12, wherein when the graphene layers and the metallic copper layers are alternately stacked on the surface of the copper foil core layer, at least one of the metallic copper layers is formed by a physical vapor deposition method or an electrochemical deposition method.

15. The method according to any one of claims 12 to 14, wherein when the graphene layers and the metallic copper layers are formed on the surface of the copper foil core layer in sequence in an alternating lamination manner, the method further comprises: after a kth metal copper layer is formed, performing single crystallization treatment on the kth metal copper layer, wherein the single crystallization treatment is used for inducing the surface of the metal copper layer to be preferentially oriented along a (111) crystal plane; wherein k is at least one integer greater than 0 and less than or equal to M.

16. The method of manufacturing according to claim 10 or 11, wherein forming the shell layer on the surface of the copper foil core layer comprises:

respectively attaching at least one laminated structure to the first surface and the second surface of the copper foil core layer; each laminated structure comprises a metal copper layer and a graphene layer positioned on the surface of the metal copper layer.

17. The method of manufacturing according to claim 16, wherein forming the shell layer on the surface of the copper foil core layer further comprises:

before the first surface and the second surface of the copper foil core layer are respectively attached with at least one layer of laminated structure, a graphene layer is formed on the first surface and/or the second surface of the copper foil core layer.

18. The production method according to claim 16 or 17, wherein the laminated structure is formed by:

providing a metal copper layer;

and forming a graphene layer on the surface of the metal copper layer by a thin film transfer method or a chemical vapor deposition method.

19. The method of manufacturing according to claim 18, further comprising, before forming the graphene layer on the surface of the metallic copper layer:

and carrying out single crystallization treatment on the metal copper layer, wherein the single crystallization treatment is used for inducing the surface of the metal copper layer to be preferentially oriented along a (111) crystal plane.

20. The method of any one of claims 16-19, wherein attaching at least one laminate structure to each of the first and second surfaces of the copper foil core layer comprises:

and respectively attaching at least one laminated structure to the first surface and the second surface of the copper foil core layer by a hot pressing sintering method.

Technical Field

The application relates to the technical field of composite copper foil materials, in particular to a composite copper foil structure, a preparation method of the composite copper foil structure, a copper-clad laminate and a printed circuit board.

Background

Copper foil is a basic material in the electronic information and energy industries, and is widely used for integrated circuits, printed circuit boards, electronic components, energy storage devices and aerospace devices for signal transmission and electrical interconnection. With the development of 5G, signal transmission is developing towards high frequency and high speed, and the conductor loss of copper foil is urgently needed to be reduced so as to reduce the insertion loss of a PCB transmission line; however, the energy device is developed toward high energy density, thinning and miniaturization, and it is urgently required to improve the through-current capability of the copper foil, reduce copper loss and reduce joule heat. These demands put higher demands on the electrical conductivity of the copper foil, and it is required to prepare a high-conductivity copper foil having an electrical conductivity higher than 100% IACS. At present, the preparation method of commercial copper foil mainly comprises a rolling method and an electrolytic method, the conductivity is about 97 percent IACS, and the requirement of industry development on the conductivity of the copper foil is difficult to meet.

Disclosure of Invention

The application provides a composite copper foil structure, a preparation method thereof, a copper-clad laminate and a printed circuit board, and is used for providing a high-conductivity composite copper foil structure.

In a first aspect, the present application provides a composite copper foil structure, which includes a copper foil core layer and a shell layer, wherein the copper foil core layer has a first surface and a second surface opposite to each other along a thickness direction; the shell layers are at least positioned on the first surface and the second surface of the copper foil core layer; wherein the shell layer comprises: the graphene layer and the metal copper layer are alternately stacked, one side, close to the copper foil core layer, of the shell layer is the graphene layer, N is an integer larger than 0, M is an integer larger than 0, and M is equal to N or M is equal to N-1; the thickness of the copper foil core layer is larger than that of the metal copper layer in the shell layer.

According to the composite copper foil structure provided by the embodiment of the application, the shell layer consisting of the graphene layers and the metal copper layers which are alternately laminated is arranged on the surface of the copper foil core layer, and the conductivity of the shell layer is improved by utilizing the composite effect of the graphene and the copper, so that the surface conductivity of the composite copper foil structure is improved. Therefore, a high-conductivity composite copper foil structure can be realized by increasing the surface conductivity (i.e., shell conductivity) of the composite copper foil structure. In addition, because only the shell layer consisting of the graphene layer and the metal copper layer is arranged on the surface of the core layer, and the core layer is made of copper foil, compared with the core layer which is also made of a composite layer of the graphene layer and the metal copper layer, the cost can be reduced.

Optionally, the metal copper layer in the shell layer may be formed by a physical vapor deposition method or an electrochemical deposition method, so that compared with a method of directly forming the metal copper layer in the shell layer by using a copper foil, the thickness of the metal copper layer in the shell layer is thinner, so that the total number of graphene layers in the shell layer can be increased by reducing the thickness of the metal copper layer under the condition that the thickness of the shell layer is constant, and the conductivity of the shell layer can be further improved.

It should be noted that, in the present application, the shell layers are located on at least the first surface and the second surface of the copper foil core layer, and of course, the shell layers may be located on other surfaces of the copper foil core layer besides the first surface and the second surface, for example, all surfaces of the copper foil core layer, which is not limited herein. The setting can be specifically carried out according to the actual application requirements.

The form of the copper foil core layer is not limited in the present application, and the form of the copper foil core layer includes, but is not limited to, a foil, and may also be, for example, a columnar form, and the like, and may be specifically designed according to the actual application requirements. For example, the copper foil core may be a foil when applied to a CCL in a PCB, and the copper foil core may be a cylinder when applied to a cable. The embodiments of the present application are only schematically described by taking the form of the copper foil core layer as a foil.

This application does not do the restriction to the number of piles of graphite alkene layer and metallic copper layer in the shell layer, because graphite alkene layer and metallic copper layer are set up in turn, the number of piles of metallic copper layer can be the same with the number of piles of graphite alkene layer, N equals M promptly, and the outermost rete of shell layer is the metallic copper layer like this. Of course, the number of layers of the metallic copper layer may also be one less than that of the graphene layer, i.e., N +1, so that the outermost film layer of the shell layer is the graphene layer.

For example, the copper foil core layer may be formed using a commercially available rolled copper foil or an electrolytic copper foil, and is not limited thereto.

The thickness of the copper foil core layer is not limited in the present application, and may be determined according to practical application requirements, for example, taking a CCL applied in a PCB as an example, the thickness of the copper foil core layer may be set to be between 0.5oz and 6oz, and for example, the thickness of the copper foil core layer is controlled to be between 0.5oz and 3 oz.

Optionally, in order to improve the interface bonding force between the copper foil core layer and the graphene layer in the shell layer, single crystallization treatment may be performed on the copper foil core layer to induce the surface of the copper foil core layer to be preferentially oriented along the (111) crystal plane.

In the present application, theoretically, the number of layers of the graphene layer in the shell layer is in a certain range, and the more the number of layers of the graphene layer, the higher the conductivity of the composite copper foil structure is, but when the number of layers of the graphene layer exceeds this range, the conductivity tends to be stable. Considering that the number of graphene layers and metal copper layers in the shell layer is greater, the number of process steps is greater, and thus the cost is higher, in particular, the number of graphene layers in the shell layer may be designed in a trade-off manner according to the cost and the conductivity, for example, in this application, the number of graphene layers N may be set to be less than or equal to 100.

Alternatively, in the present application, the number of graphene layers in the shell layer may be set to 5 to 20 layers.

The thickness of the graphene layer and the thickness of the metal copper layer in the shell layer are not limited, and the graphene layer and the metal copper layer can be designed according to actual application requirements.

For example, in the present application, the thickness of each metal copper layer in the shell layer may be controlled to be between 0.1 μm and 40 μm, and may be specifically determined according to the manufacturing method of the metal copper layer, for example, the metal copper layer is a copper foil prepared by rolling or electrolysis, and the thickness of the metal copper layer is generally less than or equal to 40 μm; the metal copper layer is an ultrathin copper foil prepared by a rolling or electrolytic method, and the thickness of the metal copper layer is generally less than or equal to 10 micrometers; the metal copper layer is a metal copper film deposited on the surface of the graphene layer in situ by a PVD method, and the thickness of the metal copper layer is generally 0.1-1 μm; the metallic copper layer is a metallic copper layer deposited in situ on the surface of the graphene layer by an electrochemical deposition method, and the thickness of the metallic copper layer is generally less than or equal to 3 μm.

Optionally, in the present application, the thickness of the metallic copper layer may be controlled to be between 0.5 μm and 6 μm, further, the thickness of the metallic copper layer may be controlled to be between 0.1 μm and 1 μm, and in a case that the thickness of the shell layer is constant, the total number of graphene layers in the shell layer may be increased by reducing the thickness of the metallic copper layer in the shell layer, so as to further improve the conductivity of the shell layer.

In the present application, the thicknesses of the different metal copper layers in the shell layer are not limited, and the thicknesses of the metal copper layers located in different layers may be the same or different.

In the application, in order to improve the interface bonding force between the graphene layer and the metal copper layer in the shell layer, single crystallization treatment can be performed on the metal copper layer to induce the surface of the metal copper layer to be preferentially oriented along the (111) crystal plane, so that the interface bonding force between the metal copper layer and the graphene layer is improved.

Alternatively, in the shell layer of the present application, all the metallic copper layers are subjected to a single crystallization process, i.e., the surface of each metallic copper layer is preferentially oriented along the (111) crystal plane.

For example, in the present application, the thickness of each graphene layer in the shell layer may be set to be 1 to 10 graphene molecule layers. Further, the thickness of the graphene layer may be set to 1 graphene molecule layer or 2 graphene molecule layers.

In this application, do not do the restriction to the thickness of different graphite alkene layers in the shell layer, the thickness of different graphite alkene layers can be the same, and of course also can not be the same.

In a second aspect, the present application provides a copper clad laminate comprising a dielectric material and a composite copper foil structure as described in the first aspect or various embodiments of the first aspect, in a stacked arrangement.

In a third aspect, the present application provides a printed circuit board comprising the copper clad laminate according to the second aspect, or the composite copper foil structure according to the first aspect or various embodiments of the first aspect.

In a fourth aspect, a method for manufacturing a composite copper foil structure provided by the present application may include: providing a copper foil core layer, wherein the copper foil core layer is provided with a first surface and a second surface which are opposite along the thickness direction; forming shell layers on at least the first surface and the second surface of the copper foil core layer; the shell layer comprises N graphene layers and M metal copper layers, the graphene layers and the metal copper layers are alternately laminated along the direction of the copper foil core layer pointing to the shell layer, one surface, close to the copper foil core layer, of the shell layer is the graphene layer, N is an integer larger than 0, M is an integer larger than 0, and M is N or M is N-1; the thickness of the copper foil core layer is larger than that of the metal copper layer in the shell layer.

In the application, in order to improve the interface bonding force between the graphene layer and the metal copper layer in the shell layer, after the metal copper layer is formed, the metal copper layer may be subjected to single crystallization treatment and then the graphene layer is formed on the metal copper layer, wherein the single crystallization treatment is used for inducing the surface of the copper foil core layer to be preferentially oriented along the (111) crystal plane.

The process of performing single crystallization on the copper foil core layer is not limited in the present application, and may be any known method.

Illustratively, in the present application, the shell layer may be formed on the surface of the copper foil core layer by the following method.

The first method comprises the following steps:

For example, in the present application, when graphene layers and metal copper layers are sequentially formed on the surface of the copper foil core layer, at least one of the graphene layers is formed by a film transfer method or a chemical vapor deposition method, and at least one of the metal copper layers is formed by a physical vapor deposition method or an electrochemical deposition method, which is not limited herein.

In this application in the shell the metal copper layer forms through physics vapor deposition method or electrochemical deposition method and compares and directly adopts the copper foil, can reduce the thickness of metal copper layer in the shell, under the certain circumstances of shell thickness, can increase the total number of piles of graphite alkene layer in the shell through the thickness that reduces the metal copper layer in the shell to further promote the conductivity of shell.

For example, in a possible implementation manner, each of the graphene layers in the shell layer is formed by using a chemical vapor deposition method, and each of the metallic copper layers in the shell layer is formed by using a physical vapor deposition method or an electrochemical deposition method.

Alternatively, in another possible implementation manner, each graphene layer in the shell layer is formed by using a thin film transfer method, and each metal copper layer in the shell layer is formed by using a physical vapor deposition method or an electrochemical deposition method.

Illustratively, in the present application, at least one metallic copper layer is single-crystallized. That is, in the present application, after the kth metallic copper layer is formed, a single crystallization treatment may be further performed on the kth metallic copper layer, where the single crystallization treatment is used to induce the surface of the kth metallic copper layer to preferentially orient along a (111) crystal plane; wherein k is at least one integer greater than 0 and less than or equal to M. Taking M as 5 as an example, k is 1, for example, after the 1 st metallic copper layer is formed, the 1 st metallic copper layer is subjected to single crystallization, that is, only the 1 st metallic copper layer is subjected to single crystallization, and the 2 nd graphene layer is formed on the 1 st metallic copper layer subjected to single crystallization. For example, k takes 1 and 3, and after the 1 st metal copper layer is formed, the 1 st metal copper layer is subjected to single crystallization treatment; after forming the 3 rd metal copper layer, performing single crystallization treatment on the 3 rd metal copper layer; that is, only the 1 st and 3 rd metallic copper layers are subjected to single crystallization, the 2 nd graphene layer is formed on the 1 st metallic copper layer subjected to single crystallization, and the 4 th graphene layer is formed on the 3 rd metallic copper layer subjected to single crystallization.

The second method comprises the following steps:

forming the shell layer on the surface of the copper foil core layer may include: respectively attaching at least one laminated structure to the first surface and the second surface of the copper foil core layer; each laminated structure comprises a metal copper layer and a graphene layer positioned on the surface of the metal copper layer.

For example, at least one laminated structure may be attached to the first surface and the second surface of the copper foil core layer by a hot press sintering method.

Illustratively, the stacked structure is formed by: providing a metal copper layer; and forming a graphene layer on the surface of the metal copper layer by a thin film transfer method or a chemical vapor deposition method.

For example, forming the shell layer on the surface of the copper foil core layer may further include: before the first surface and the second surface of the copper foil core layer are respectively attached with at least one layer of laminated structure, a graphene layer is formed on the first surface and/or the second surface of the copper foil core layer.

Of course, the first method and the second method may be combined in specific implementation, and are not limited herein. For example, when N is 4, a first graphene layer may be formed on the surface of the copper foil core layer, a first metal copper layer may be formed on the first graphene layer, and then a 3-layer laminated structure may be bonded to the first metal copper layer.

It should be noted that, in the present application, the shell layers may be formed on different surfaces of the copper foil core layer at the same time, for example, the shell layers may be formed on the first surface and the second surface of the copper foil core layer at the same time; the shell layers may be formed on different surfaces of the copper foil core layer in sequence, for example, the shell layers may be formed on a first surface of the copper foil core layer and then formed on a second surface of the copper foil core layer.

The technical effects that can be achieved by any one of the second aspect to the fourth aspect may refer to technical effect descriptions that can be achieved by any one of the possible designs of the first aspect, and will not be repeated herein.

Drawings

Fig. 1 is a schematic structural diagram of a composite copper foil structure according to an embodiment of the present disclosure;

fig. 2 is a schematic structural view of another composite copper foil structure provided in the embodiments of the present application;

fig. 3 is a schematic flow chart illustrating a method for manufacturing a composite copper foil structure according to an embodiment of the present disclosure;

fig. 4 is a schematic flow chart illustrating another method for fabricating a composite copper foil structure according to an embodiment of the present disclosure;

fig. 5 is a schematic flow chart illustrating another method for fabricating a composite copper foil structure according to an embodiment of the present disclosure;

FIG. 6 is a schematic view of a composite copper foil structure prepared using a method of preparation provided in one embodiment of the present application;

FIG. 7 is a schematic view of a composite copper foil structure prepared using a method of preparation according to another embodiment of the present application;

FIG. 8 is a schematic view of a composite copper foil structure prepared using a method of preparation according to another embodiment of the present application;

FIG. 9 is a schematic view of a composite copper foil structure prepared using a method of preparation according to another embodiment of the present application;

FIG. 10 is a schematic view of a composite copper foil structure prepared using a method of preparation provided in another embodiment of the present application;

fig. 11 is a schematic flow chart illustrating another method for fabricating a composite copper foil structure according to an embodiment of the present disclosure;

FIG. 12 is a schematic diagram illustrating the fabrication of a composite copper foil structure according to one embodiment of the present application;

fig. 13 is a schematic flow chart illustrating another method for fabricating a composite copper foil structure according to an embodiment of the present disclosure;

FIG. 14 is a schematic diagram of a composite copper foil structure according to another embodiment of the present application;

fig. 15 is a schematic flow chart illustrating another method for fabricating a composite copper foil structure according to an embodiment of the present disclosure;

FIG. 16 is a schematic diagram of a composite copper foil structure prepared according to yet another embodiment of the present application;

fig. 17 is a schematic structural diagram of a copper clad laminate provided in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings.

It should be noted that in this specification, like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

In the description of the present application, it should be noted that the terms "middle", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. The words used in this application to describe positions and orientations are provided by way of example in the drawings and can be modified as required and are intended to be within the scope of the present invention. The drawings of the present application are for illustrating relative positional relationships only and do not represent true scale. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Hereinafter, some terms in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

Chemical Vapor Deposition (CVD): is a chemical technology for producing solid materials with high purity and good performance. The semiconductor industry uses this technique to grow thin films. A typical CVD process exposes a wafer (substrate) to one or more different precursors, which chemically react and/or chemically decompose on the substrate surface to produce a film to be deposited. Different byproducts are usually produced concomitantly in the reaction process, but are mostly carried away with the gas flow and are not left in the reaction chamber (reaction chamber).

Physical Vapor Deposition (PVD): under the condition of vacuum, it adopts physical method to gasify the material source-solid or liquid surface into gas atom, molecule or partially ionize into ion, and through the process of low-pressure gas (or plasma), it deposits film with a certain special function on the surface of the substrate. The main methods of physical vapor deposition include vacuum evaporation, sputter coating, arc plasma coating, ion coating, and molecular beam epitaxy. Physical vapor deposition techniques have been developed to date to deposit not only metal films, alloy films, but also compound, ceramic, semiconductor, polymer films, and the like.

Electrochemical Deposition (Electrochemical Deposition): the method refers to a technique of forming a plating layer by transferring current through positive and negative ions in an electrolyte solution under the action of an external electric field and performing an oxidation-reduction reaction of gain and loss electrons on an electrode. The reduction of the metal ions at the cathode occurs to obtain a metal coating, which is called electroplating. Oxidation of the anodic metal occurs at the anode to form a suitable oxide film, which is referred to as electrochemical oxidation of the metal, or simply as electro-oxidation of the metal.

Film transfer method: the thin film is separated from one substrate and transferred onto another substrate (target substrate).

To facilitate understanding of the composite copper foil structure provided in the embodiments of the present application, first, an application scenario of the composite copper foil structure is described, and the composite copper foil structure is widely used for signal transmission and electrical interconnection of integrated circuits, Printed Circuit Boards (PCBs), electronic components, energy storage devices, and aerospace devices. Taking a PCB as an example, the PCB is a printed circuit having different conductive patterns manufactured by selectively performing processes such as machining, etching, drilling, and Copper plating on a Copper Clad Laminate (CCL). The CCL, which is a substrate material in the manufacture of PCBs, mainly plays roles of interconnection conduction, insulation, and support to the PCBs, and has a great influence on the transmission speed, energy loss, characteristic impedance, and the like of signals in circuits, and thus, the performance, quality, workability in the manufacture, manufacturing level, manufacturing cost, and long-term reliability and stability of the PCBs are largely determined by the CCL. The CCL is a copper clad laminate for short, and is a plate-shaped material prepared by soaking electronic glass fiber cloth or other reinforcing materials with resin, then coating copper foil on one surface or two surfaces of the electronic glass fiber cloth or other reinforcing materials and carrying out hot pressing.

As signal transmission is developed towards high frequency and high speed, it is urgently needed to reduce the conductor loss in the PCB so as to reduce the insertion loss of the transmission line; the energy device is developed towards high energy density, thinning and miniaturization, and the improvement of the through-current capacity of the copper foil, the reduction of copper loss and the reduction of joule heat are urgently needed. These demands put higher demands on the electrical conductivity of the copper foil, and it is required to prepare a high-conductivity copper foil having an electrical conductivity higher than 100% IACS. At present, the preparation method of commercial copper foil mainly comprises a rolling method and an electrolytic method, the conductivity is about 97 percent IACS, and the requirement of industry development on the conductivity of the copper foil is difficult to meet.

In this regard, the present application provides a high conductivity composite copper foil structure that is particularly useful in high frequency signal applications (e.g., at signal frequencies greater than 1 MHZ). In order to facilitate understanding of the technical solution of the present application, the high conductivity composite copper foil structure provided in the present application will be specifically described below with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 and 2, fig. 1 is a schematic structural view of a composite copper foil structure provided in an embodiment of the present application, and fig. 2 is a schematic structural view of another composite copper foil structure provided in an embodiment of the present application. The composite copper foil structure 10 comprises a copper foil core layer 11 and a shell layer 12, wherein the copper foil core layer 11 is provided with a first surface and a second surface which are opposite along a thickness direction X; the shell layer 12 is at least positioned on the first surface and the second surface of the copper foil core layer 11; wherein the shell layer 12 comprises: n-layer graphene layer: 1211 to 121N and M metal copper layers 1221 to 122M, the graphene layers 121N (N is an arbitrary integer from 1 to N) and the metal copper layers 122M (M is an arbitrary integer from 1 to M) are alternately stacked in an X direction, one surface of the shell layer 12 close to the copper foil core layer 11 is the graphene layer 121_ N, N is an integer greater than 0, M is N or M is N-1, and the thickness of the copper foil core layer 11 is greater than that of the metal copper layers 122N in the shell layer 12. For example, in fig. 1, N is equal to 4, and M is equal to 4, and one side of the shell layer 12 close to the copper foil core layer 11 is a first graphene layer 1211, and in the shell layer 12, and in a direction pointing to the shell layer 12 along the copper foil core layer 11, the first graphene layer 1211, a first metal copper layer 1221, a second graphene layer 1212, a second metal copper layer 1222, a third graphene layer 1213, a third metal copper layer 1223, a fourth graphene layer 1214, and a fourth metal copper layer 1224 are sequentially included. In fig. 2, it is illustrated that N is equal to 4 and M is equal to 3, and a first graphene layer 1211 is disposed on one side of the shell layer 12 close to the copper foil core layer 11, and in the shell layer 12, and along a direction of the copper foil core layer 11 toward the shell layer 12, the first graphene layer 1211, the first metal copper layer 1221, the second graphene layer 1212, the second metal copper layer 1222, the third graphene layer 1213, the third metal copper layer 1223, and the fourth graphene layer 1214 are sequentially disposed.

Based on the skin effect of the conductor, when an alternating current or an alternating electromagnetic field exists in the conductor, the current distribution in the conductor is uneven, the current is concentrated on the skin part of the conductor, namely the current is concentrated on a thin layer on the outer surface of the conductor, and the closer to the surface of the conductor, the higher the current density is. Therefore, in the composite copper foil structure provided by the embodiment of the application, the shell layer composed of the graphene layers and the metal copper layers which are alternately stacked is arranged on the surface of the copper foil core layer, and the surface conductivity of the composite copper foil structure is improved by utilizing the composite effect of the graphene and the copper, so that the composite copper foil structure with high conductivity can be provided. In addition, because only the shell layer consisting of the graphene layer and the metal copper layer is arranged on the surface of the core layer, and the core layer is made of copper foil, compared with the core layer which also adopts a composite layer of the graphene layer and the metal copper layer, the cost can be reduced.

Optionally, the metal copper layer in the shell layer may be formed by a PVD method or an electrochemical deposition method, and thus, compared with a case where the metal copper layer in the shell layer is directly formed by using a copper foil, the metal copper layer in the shell layer has a thinner thickness, so that the total number of graphene layers in the shell layer may be increased by reducing the thickness of the metal copper layer under a certain thickness of the shell layer, and thus, the conductivity of the shell layer may be further improved.

The form of the copper foil core layer is not limited in the present application, and the form of the copper foil core layer includes, but is not limited to, a foil, and may also be, for example, a columnar form, and the like, and may be specifically designed according to the actual application requirements. For example, the copper foil core may be a foil when applied to a CCL in a PCB, and the copper foil core may be a cylinder when applied to a cable. The present embodiment is described schematically only by taking the form of the copper foil core layer as a plate.

For example, the copper foil core layer may be formed using a commercially available rolled copper foil or an electrolytic copper foil, and is not limited thereto.

In this application, 1oz means that copper weighing 1oz is uniformly laid down at 1 square foot (ft)²) The thickness achieved over the area of (a). The average thickness of the copper foil is expressed by the weight per unit area and is expressed by a formula, namely 1oz is 28.35g/ft²，1ft²＝0.09290304m²And 1oz is about 0.035 mm.

Optionally, in order to improve the interface bonding force between the copper foil core layer and the graphene layer in the shell layer, single crystallization treatment may be performed on the copper foil core layer, where the single crystallization treatment is used to induce the surface of the copper foil core layer to preferentially orient along the (111) crystal plane.

Alternatively, in the present application, the number of graphene layers in the shell layer may be set to 5 to 20 layers.

In the application, in order to improve the interface bonding force between the graphene layer and the metal copper layer in the shell layer, single crystallization treatment may be performed on the metal copper layer to induce the surface of the metal copper layer to be preferentially oriented along the (111) crystal plane, so as to improve the interface bonding force between the metal copper layer and the graphene layer. Of course, in the present application, the metal layer may not be subjected to the single crystallization process, and is not limited thereto.

Illustratively, in order to improve the interfacial bonding force between the graphene layer and the metallic copper layer in the shell layer, at least one metallic copper layer in the shell layer is subjected to single crystallization treatment.

Optionally, in the shell layer of the present application, all the metallic copper layers are subjected to a single crystallization process to induce a preferred orientation of the surface of each metallic copper layer along the (111) crystal plane.

For example, in the present application, the thickness of each graphene layer in the shell layer may be set to be 1 to 10 graphene molecular layers. Further, the thickness of the graphene layer may be set to 1 graphene molecule layer or 2 graphene molecule layers.

The embodiment of the application also provides a preparation method of the composite copper foil structure, and as shown in fig. 3, the preparation method can comprise the following steps:

step S101, providing a copper foil core layer, wherein the copper foil core layer is provided with a first surface and a second surface which are opposite along the thickness direction.

Step S102, forming shell layers on at least the first surface and the second surface of the copper foil core layer.

The shell layer comprises N graphene layers and M metal copper layers, the graphene layers and the metal copper layers are alternately stacked, the graphene layers are close to one side of the copper foil core layer in the shell layer, N is an integer larger than 0, M is an integer larger than 0, and the thickness of the copper foil core layer is larger than that of the metal copper layers in the shell layer.

In order to improve the interface bonding force between the copper foil core layer and the shell layer, referring to fig. 4, between steps S101 and S102, step S103 may be further included: and carrying out single crystallization treatment on the copper foil core layer, wherein the single crystallization treatment is used for inducing the surface of the copper foil core layer to be preferentially oriented along a (111) crystal plane.

The process of performing single crystallization on the copper foil core layer is not limited in the present application, and may be any known method.

Specifically, in the present application, the shell layer may be formed on the surface of the copper foil core layer by the following method.

The first method comprises the following steps:

graphene layers and metal copper layers which are alternately stacked are sequentially formed on the surface of the copper foil core layer until N layers of the graphene layers and M layers of the metal copper layers are formed. That is, a shell layer is formed on the surface of the copper foil core layer by layer, taking an example that the shell layer includes 3 graphene layers and 3 metallic copper layers, referring to fig. 5, forming the shell layer on the surface of the copper foil core layer may include the following steps:

step S201, forming a first graphene layer on the surface of the copper foil core layer;

step S202, forming a first metal copper layer on the first graphene layer;

step S203, forming a second graphene layer on the first metal copper layer;

step S204, forming a second metal copper layer on the second graphene layer;

step S205, forming a third graphene layer on the second metal copper layer;

and S206, forming a third metal copper layer on the third graphene layer.

Optionally, each metal copper layer in the present application is subjected to single crystallization, so as to improve the interfacial bonding force between each graphene layer in the shell layer and the metal copper layer adjacent to the graphene layer.

The second method comprises the following steps:

as shown in fig. 6 and 7, forming the shell layer 12 on the surface of the copper foil core layer 11 may include: respectively attaching at least one laminated structure 01 to the first surface and the second surface of the copper foil core layer 11; each of the stacked structures 01 includes a metal copper layer 122 and a graphene layer 121 on a surface of the metal copper layer 122.

For example, at least one laminated structure may be attached to the first surface and the second surface of the copper foil core layer by a hot press sintering method.

Referring to fig. 6, a graphene layer 121 may be formed on one surface of the metallic copper layer 122 by a thin film transfer method, so as to form a stacked structure 01. And then, respectively attaching at least one laminated structure 01 to the first surface and the second surface of the copper foil core layer 11 to form a composite copper foil structure. In the formed composite copper foil structure, the graphene layer 121 in the laminated structure 01 may be located on the side close to the copper foil core layer 11, and the metallic copper layer 122 may be located on the side far from the copper foil core layer 11.

Referring to fig. 7, a graphene layer 121 may be formed on all surfaces of the metallic copper layer 122 by a chemical vapor deposition method, so as to form a stacked structure 01. And then, respectively attaching at least one laminated structure 01 to the first surface and the second surface of the copper foil core layer 11 to form a composite copper foil structure. In the formed composite copper foil structure, the graphene layer 121n between any two adjacent metallic copper layers 122m is formed by two graphene layers 121 in the two-layer laminated structure 01.

In order to improve the interfacial bonding force between the graphene layer and the metal copper layer in the shell layer, before the graphene layer is formed on the surface of the metal copper layer, the method may further include: and carrying out single crystallization treatment on the metal copper layer, wherein the single crystallization treatment is used for inducing the surface of the metal copper layer to be preferentially oriented along a (111) crystal plane.

For example, as shown in fig. 8 to 10, forming the shell layer 12 on the surface of the copper foil core layer 11 may further include: before the first surface and the second surface of the copper foil core layer 11 are respectively attached with at least one layer of the laminated structure 01, the graphene layer 121 is formed on the first surface and/or the second surface of the copper foil core layer 11. Fig. 8 to 10 are all schematic diagrams illustrating an example in which graphene layers 121 are formed on both the first surface and the second surface of the copper foil core layer 11.

Illustratively, in the formed composite copper foil structure, for the case where the graphene layer 121 in the laminated structure 01 is formed on one side surface of the metallic copper layer 122 by a thin film transfer method: as shown in fig. 8, the graphene layer 121 in the stacked structure 01 may be located on a side close to the copper foil core layer 11, and the metallic copper layer 122 may be located on a side far from the copper foil core layer 11; alternatively, as shown in fig. 9, the graphene layer 121 in the stacked structure 01 may be located on the side away from the copper foil core layer 11, and the metallic copper layer 122 may be located on the side close to the copper foil core layer 11.

Illustratively, in the formed composite copper foil structure, for the case where the graphene layer 121 is formed on all surfaces of the metal copper layer 122 by the chemical vapor deposition method in the laminated structure 01, the formed composite copper foil structure is as shown in fig. 10, and the first graphene layer 1211 located between the first metal copper layer 1221 and the copper foil core layer 11 is formed by the graphene layer 121 in the first laminated structure 01 and the graphene layer 121 formed on the surface of the copper foil core layer 11.

The present application will be described in detail with reference to specific examples. It should be noted that the present embodiment is for better explaining the present application, but does not limit the present application.

The first embodiment,

In this embodiment, a laminated growth method (in-situ growth of graphene layer + in-situ growth of metal copper layer) is adopted to prepare a composite copper foil structure, as shown in fig. 11, and with reference to fig. 12, the method specifically includes the following steps:

step S401, performing single crystallization on the copper foil core layer to prepare a copper foil core layer having a large single crystal domain Cu (111), and forming a structure shown in fig. 12 (a).

Wherein the Cu (111) crystal plane is highly oriented in the thickness direction of the copper foil core layer.

The process of performing single crystallization on the copper foil core layer is not limited in the present application, and may be any known method.

Illustratively, commercial copper foil (0.5oz) may be cut to 20cm by 20cm width, placed on a temperature-resistant quartz carrier, and then the entire apparatus placed in a cvd tube furnace; introducing inert gas argon (with the purity of 99.99 percent) with the flow rate of more than 300sccm to remove residual oxygen in the chemical vapor deposition tubular furnace; then hydrogen (purity 99.99%) is introduced into the reactor to 1 atmospherePressure (1X 10)⁵pa); then raising the temperature in the furnace of the chemical vapor deposition tube furnace to 800-1100 ℃, simultaneously introducing hydrogen, controlling the hydrogen flow to be 2-500 sccm, and annealing the copper foil core layer for 0.5-3 hours; and then slowly cooling to room temperature to obtain the copper foil core layer of the Cu (111) in the larger single crystal domain area.

Step S402 is to grow a graphene layer 1211 in situ on the surface of the copper foil core layer 11 by using a CVD method, thereby forming a structure shown in fig. 12 (b).

The process for growing the graphene layer by CVD is not limited in the present application, and may be any known method.

Illustratively, after the annealing is complete, the methane (CH) feed is started₄) Mixed gas of the above-mentioned metal oxide and inert gas, CH in the mixed gas₄The content is 200ppm to 20000ppm, the flow rate of the mixed gas is 0.2sccm to 50sccm, and H is adjusted₂The flow rate is 0.2 sccm-50 sccm, the inert gas flow rate is kept unchanged, the pressure is maintained at 1 atmospheric pressure, the growth time is 10 min-20 h, and a graphene layer is grown on the surface of the copper foil core layer in a covering manner.

Step S403, growing a metallic copper layer 1221 in situ on the surface of the graphene layer 1211 by using a PVD method or an electrochemical deposition method, so as to form a structure shown in fig. 12 (c).

The process of growing the metallic copper layer by PVD method is not limited in this application and may be any known method. PVD processes generally include vacuum evaporation, sputter coating, arc plasma coating, ion coating, and molecular beam epitaxy.

For example, a magnetron sputtering method may be used to successively sputter a metal copper layer on the graphene layer on the first surface side and the graphene layer on the second surface side, and in specific implementation, a high-purity copper target (99.99%) is used, and the metal copper layer is sputtered on the graphene layer surface by high-vacuum sputtering. The magnetron sputtering conditions are as follows: sputtering pressure 4 x 10^-4Pa, and the power is 500W. The thickness of the metallic copper layer may be 500 nm.

The process for growing the metallic copper layer by electrochemical deposition is not limited and may be any known process.

Exemplary embodiments of the inventionThe copper foil core layer with the graphene layer covered on the surface is placed on a cathode of an electroplating bath, a phosphorus copper plate can be used as an anode, and the current density and the electroplating time required by electroplating are controlled according to the thickness of the metal copper layer. In one embodiment, the formulation of the plating solution used for copper plating may be: 300g/L CuSO₄·5H₂O，50g/L H₂SO₄10g/L glucose, the current density may be 3A/dm²The temperature may be 25 ℃. After a period of electroplating, a layer of metal copper layer with the thickness of about 1 mu m can be covered on the graphene layer on the surface of the copper foil core layer, a direct-current power supply is closed, the cathode plate is taken out of the plating solution, the cathode plate is cleaned by ethanol, the surface is dried by nitrogen, the electroplating of the metal copper layer is completed, and the graphene layer is completely wrapped in the metal copper layer.

Optionally, after step S403, step S404 may also be performed: the metallic copper layer is annealed to perform a single crystallization process.

The process of performing the single crystallization treatment on the metallic copper layer is not limited in the present application, and may be any known method.

Illustratively, the already prepared composite film layer (metallic copper layer/graphene layer/copper foil core layer) may be annealed: placing the composite film layer on a temperature-resistant quartz carrier, and then placing the whole device into chemical vapor deposition equipment; introducing inert gas argon (with the purity of 99.99 percent) with the flow rate of more than 300sccm to remove residual oxygen in the equipment; then hydrogen (purity 99.99%) was introduced to 1 atmosphere (1X 10)⁵pa); then, when the temperature in the heating furnace in the equipment is raised to 500 ℃ within 30 minutes, H is introduced₂，H₂Keeping the temperature for 30 minutes at the flow rate of 2-500 sccm, raising the temperature from 500 ℃ to 1000 ℃ within 30 minutes, keeping the temperature for 30 minutes for the second time, and then naturally cooling to room temperature.

Thereafter, steps S402, S403 and S404N are repeated several times to form a composite copper foil structure as shown in fig. 12 (d).

For example, when the magnetron sputtering method is used to sputter the metal copper layer in step S403, steps S402, S403 and S404 may be repeated about thirty times, so that a composite copper foil structure with a thickness of about 1oz may be obtained.

Illustratively, when the metallic copper layer is grown by the electrochemical deposition method in step S403, steps S402, S403 and S404 may be repeated seventeen or so times, so that a composite copper foil structure with a thickness of about 1oz may be obtained.

In this embodiment, step S401 and step S404 are not necessarily performed, and may be performed or not performed, and are not limited herein.

In the first embodiment, the metal copper layer in the shell layer is formed by a PVD method or an electrochemical deposition method, so that the thickness of the metal copper layer in the shell layer can be reduced, and the total number of graphene layers in the shell layer can be increased by reducing the thickness of the metal copper layer in the shell layer under the condition that the thickness of the shell layer is constant, thereby further improving the conductivity of the shell layer.

Example II,

In this embodiment, a composite copper foil structure is prepared by a layer-by-layer formation method (a graphene layer is formed by a thin film transfer method + a metal copper layer is grown in situ), as shown in fig. 13, and in combination with fig. 14, the method specifically includes the following steps:

step S501, performing single crystallization on the copper foil core layer to prepare a copper foil core layer having a large single crystal domain Cu (111), and forming a structure shown in fig. 14 (a).

Wherein the Cu (111) crystal plane is highly oriented in the thickness direction of the copper foil core layer.

The process of performing single crystallization on the copper foil core layer is not limited in the present application, and may be any known method.

Illustratively, commercial copper foil (0.5oz) may be cut to 20cm by 20cm width, placed on a temperature-resistant quartz carrier, and then the entire apparatus placed in a cvd tube furnace; introducing inert gas argon (with the purity of 99.99 percent) with the flow rate of more than 300sccm to remove residual oxygen in the chemical vapor deposition tubular furnace; then hydrogen (purity 99.99%) was introduced to 1 atmosphere (1X 10)⁵pa); then raising the temperature in the furnace of the chemical vapor deposition tube furnace to 800-1100 ℃, simultaneously introducing hydrogen, controlling the hydrogen flow to be 2-500 sccm, and annealing the copper foil core layer for 0.5-3 hours; then slowly cooling to the roomAnd (3) obtaining the copper foil core layer with a large single crystal domain Cu (111) at a high temperature.

Step S502, laying a graphene layer 1211 on the first surface and the second surface of the copper foil core layer 11 sequentially by using a film transfer method, so as to form the structure shown in fig. 14 (b).

The process for preparing the graphene layer by the thin film transfer method in this embodiment is not limited, and may be any known method. For example, the graphene layer formed on the substrate may be transfer-bonded to the first surface and the second surface of the copper foil core layer by peeling from the substrate, and the substrate may be a copper foil substrate, a sapphire substrate, or the like, which is not limited herein.

Optionally, ethanol may be uniformly dropped on the surface of the copper foil core layer before the graphene layer is laid, and after the ethanol is completely volatilized, the graphene layer may be tightly bonded to the surface of the copper foil core layer.

Step S503, growing a metallic copper layer 1221 in situ on the surface of the graphene layer 1211 by using an electrochemical deposition method, so as to form a structure shown in fig. 14 (c).

The process for growing the metallic copper layer by electrochemical deposition is not limited and may be any known process.

For example, a copper foil core layer with a graphene layer coated on the surface is placed at the cathode of an electroplating bath, and the current density and the electroplating time required by electroplating are controlled according to the thickness of a metal copper layer. In one embodiment, the formulation of the plating solution used for copper plating may be: 300g/L CuSO₄·5H₂O，50g/L H₂SO₄10g/L glucose, the current density may be 3A/dm²The temperature may be 25 ℃. After a period of electroplating, a layer of metal copper layer with the thickness of about 1 mu m can be covered on the graphene layer on the surface of the copper foil core layer, a direct-current power supply is closed, the cathode plate is taken out of the plating solution, the cathode plate is cleaned by ethanol, the surface is dried by nitrogen, the electroplating of the metal copper layer is completed, and the graphene layer is completely wrapped in the metal copper layer.

Optionally, after step S503, step S504 may also be performed: the metallic copper layer is annealed to perform a single crystallization process.

The process of performing the single crystallization treatment on the metallic copper layer is not limited in the present application, and may be any known method.

Thereafter, steps S502, S503 and S504N are repeated once more, forming a composite copper foil structure as shown in fig. 14 (d).

For example, steps S502, S503 and S504 may be repeated for about thirty-four times, so that a composite copper foil structure of about 3oz thickness may be obtained.

Optionally, when the graphene layer is formed on the metal copper layer by using a thin film transfer method, ethanol may be uniformly dropped on the surface of the metal copper layer before the graphene layer is laid, and after the ethanol is completely volatilized, the graphene layer may be tightly bonded on the surface of the metal copper layer.

In this embodiment, step S501 and step S504 are not necessarily performed, and may be performed or not performed, and are not limited herein.

In the second embodiment, the metal copper layer in the shell layer is formed by an electrochemical deposition method, so that the thickness of the metal copper layer in the shell layer can be reduced, and the total number of graphene layers in the shell layer can be increased by reducing the thickness of the metal copper layer in the shell layer under the condition that the thickness of the shell layer is constant, so that the conductivity of the shell layer is further improved.

Example III,

In this embodiment, a composite copper foil structure is prepared by a hot-pressing sintering method, as shown in fig. 15, and with reference to fig. 16, the method specifically includes the following steps:

step S601, carrying out single crystallization treatment on the copper foil core layer and the metal copper layer in the laminated structure.

The process of single crystallization of the copper foil core layer and the metal copper layer is not limited in the present application, and may be any known method.

For example, a commercial copper foil with a thickness of 1oz can be cut into a width of 20cm by 20cm to form a copper foil core layer, a commercial copper foil with a thickness of 6 μm can be cut into a width of 20cm by 20cm to form a metal copper layer, then the copper foil core layer and the metal copper layer are placed on a temperature-resistant quartz carrier, and then the whole device is placed into a chemical vapor deposition tube furnace; introducing inert gas argon (with the purity of 99.99 percent) with the flow rate of more than 300sccm to remove residual oxygen in the chemical vapor deposition tubular furnace; then hydrogen (purity 99.99%) was introduced to 1 atmosphere (1X 10)⁵pa); then raising the temperature in the furnace of the chemical vapor deposition tube furnace to 800-1100 ℃, simultaneously introducing hydrogen, controlling the hydrogen flow to be 2-500 sccm, and annealing the copper foil core layer for 0.5-3 hours; and then slowly cooling to room temperature to obtain the copper foil core layer of the Cu (111) in the larger single crystal domain area.

Alternatively, the graphene layer 1211 may be grown on the surface of the copper foil core layer 11 by CVD to form the structure shown in fig. 16 (a).

Step S602, a stacked structure is prepared.

In specific implementation, the graphene layer 121 may be grown in situ on the upper and lower surfaces of the metallic copper layer 122 by CVD to form a stacked structure 01 as shown in fig. 16 (b).

Illustratively, growing the graphene layer in situ using a CVD process may include: after the annealing, the introduction of methane (CH) was started₄) Mixed gas of the above-mentioned metal oxide and inert gas, CH in the mixed gas₄The content is 200ppm to 20000ppm, the flow rate of the mixed gas is 0.2sccm to 50sccm, and H is adjusted₂The flow rate is 0.2 sccm-50 sccm, the inert gas flow rate is kept unchanged, the pressure is maintained at 1 atmospheric pressure, the growth time is 10 min-20 h, and a graphene layer is grown on the surface of the copper foil core layer in a covering manner.

Alternatively, in-situ growth of the graphene layer on the surface of the metal copper layer by using a CVD method and growth of the graphene layer on the surface of the copper foil core layer can be performed simultaneously.

Step S603 is to laminate at least one laminate structure 01 on each of the first surface side and the second surface side of the copper foil core layer 11, thereby forming a structure shown in fig. 16 (c).

Step S604 is to perform hot-press sintering on the laminated copper foil core layer 11 and the laminated structure 01 to form a composite copper foil structure shown in fig. 16 (d).

The hot press sintering may include any one of hot press sintering under inert gas protection, microwave sintering, spark plasma sintering, and the like, and is not limited thereto.

For example, a 1oz thick copper foil core layer coated with a graphene layer and a 12-layer laminated structure may be laminated, and then hot-pressed and sintered at 700 to 1100 ℃ under a pressure of 50 to 200MPa for 10 to 120 minutes, so that a composite copper foil structure having a thickness of about 3oz may be obtained. The hot-pressing sintering can enable the film layers to be combined in a densification mode, enables the crystal grains of the copper foil substrate to be further oriented, improves the single crystallization degree of the copper foil and the preferred orientation of the Cu (111) crystal face, improves the interface bonding force of the copper foil and the graphene, is favorable for realizing the electronic doping effect, and improves the conductivity of the composite copper foil structure.

The composite copper foil structure provided by the embodiment of the application has higher conductivity, so the composite copper foil structure can be applied to copper-clad laminates and printed circuit boards in the high-frequency and high-speed field with low loss characteristic and the power electronic field with low copper loss and large through current characteristic.

The high-end board loss (M8:0.7dB @ in @28GHz) in the current industry is difficult to support a high-speed link and is evolved based on PCB connection, and a low-loss board is urgently needed to be greatly broken through; with current mainstream materials, the medium loss has a small proportion, and the total loss is dominated by the copper loss. The technical path for reducing copper loss by reducing the roughness of the copper foil is approaching the physical limit, and therefore, the conductivity of the copper foil needs to be improved to reduce the copper loss. For an energy power electronic plane magnetic structure, joule heat is greatly accumulated due to copper loss of a PCB winding, and the working efficiency of an MOS (metal oxide semiconductor) tube is severely restricted, so that the heat source also needs to be reduced by improving the conductivity of the copper of the winding. Based on this, the composite copper foil structure provided by the embodiment of the application can be applied to a high-speed (e.g. 112G) PCB architecture and a power electronic plane magnetic architecture.

In addition, the composite copper foil structure provided by the embodiment of the present application can also be applied to lead frames, connectors, flanges, heat sinks, and other scenarios, which are not limited herein.

Accordingly, referring to fig. 17, the present application also provides a copper clad laminate that may include a dielectric material 20 and any of the composite copper foil structures 10 described above provided by the embodiments of the present application in a stacked arrangement. In specific implementation, as shown in fig. 17, the composite copper foil structure 10 may be located on both sides of the dielectric material 20, or may be located on only one side of the dielectric material, which is not limited herein. Because the principle of solving the problems of the copper clad laminate is similar to that of the composite copper foil structure, the implementation of the copper clad laminate can refer to the implementation of the composite copper foil structure, and repeated details are not repeated.

In a specific implementation, the composite copper foil structure may be surface-roughened by a known method, and then, the CCL may be prepared by a known hot-pressing method with a dielectric material, which is not limited herein.

In the composite copper foil structure applied to the copper clad laminate, the outermost layer of the shell layer may be a metal copper layer.

Correspondingly, the application also provides a printed circuit board which comprises the copper clad laminate or the composite copper foil structure provided by the embodiment of the application. Because the principle of solving the problems of the printed circuit board is similar to that of the composite copper foil structure, the implementation of the printed circuit board can refer to the implementation of the composite copper foil structure, and repeated details are not repeated.

In practice, printed circuits with different conductive patterns can be made by processes such as machining, etching, drilling, and copper plating.

In conclusion, the shell layer prepared by laminating the graphene layer and the metal copper layer can obtain higher conductivity, can reduce copper loss, and has important application prospect in electronic information industries such as electronic circuits, integrated circuits and the like. In addition, the structural design of the copper foil core layer and the shell layer is adopted, so that the conductivity of the composite copper foil structure can be improved, the composite copper foil structure can be endowed with large through-current capacity, the preparation cost of the composite copper foil structure is reduced, and the composite copper foil structure has important application in the field of high-frequency power supply PCBs. In addition, the PCB prepared by using the composite copper foil structure can obviously reduce copper loss and improve through-flow and heat-conducting capacity, and has important application in the fields of high speed, power electronics and the like.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

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Composite copper foil structure, preparation method thereof, copper-clad laminate and printed circuit board

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