TWI889043B - Flexible copper clad laminate and flexible printed circuit board - Google Patents

Abstract

The present invention relates to a flexible copper clad laminate (FCCL) for use in electronic boards such as flexible circuit boards and flexible printed circuit boards (FPCB) including it. In one embodiment of the present invention, the flexible copper clad laminate for electronic boards comprises: a base material layer made of flexible fluororesin composite material; a composite material layer formed on at least one side of the base material layer and including a first material layer with a higher tensile strength than the base material layer and a second material layer is made of a fluororesin composite material; and a conductive layer formed on the composite material layer.

Description

Flexible copper foil laminate and flexible printed circuit board for electronic board

The present invention relates to a flexible copper foil laminate (FCCL) for use in electronic boards such as flexible circuit boards and a flexible printed circuit board (FPCB) including the same.

As electronic products gradually become smaller, thinner, lighter and more multifunctional, flexible printed circuit boards (FPCB) are widely used in small and medium-sized electronic products such as smartphones, cameras, and laptops. Flexible printed circuit boards have conductive patterns formed on insulating substrate films. Flexible copper foil laminates (FCCL) are the core materials of flexible printed circuit boards. Unlike copper foil laminates (CCL), they are thin and flexible.

A flexible copper foil laminate is prepared by laminating copper foil on one or both sides of an insulating base film, and a flexible printed circuit board can be prepared by etching the copper foil of the flexible copper foil laminate to form a conductive pattern. The flexible copper foil laminate and flexible printed circuit board prepared in this way are not only flexible but also can be repeatedly deformed, so the performance of the substrate can be maintained even when deformed.

Figure 1 is a diagram showing an existing flexible copper foil laminate, part (a) is a cross-sectional structural diagram of the existing flexible copper foil laminate, and part (b) is an enlarged diagram of the joint surface "A" of the copper foil and the adhesive.

The existing flexible copper foil laminate is composed of a flexible substrate film 101 and copper foils 104 and 105. The copper foils 104 and 105 are attached to one or both sides of the substrate film 101 through adhesives 102 and 103. The substrate film 101 may include at least one of a polyimide (PI) film, a polyethylene naphthalate (PEN) film, and a liquid crystal polymer (LCP) film.

In the existing flexible copper foil laminate, since the base film 101 and the copper foils 104 and 105 are attached through the adhesives 102 and 103, the surface roughness of the copper foils 104 and 105 in contact with the adhesives 102 and 103 (referred to as copper foil roughness) becomes more than 1μm.

As shown in part (b) of Figure 1, in conductors such as copper foil, high-frequency current flows only around the surface of the conductor (copper foil) due to the skin effect. If the roughness of the copper foil increases, a large amount of signal loss will occur, and heat problems will arise during the signal transmission process. Therefore, existing flexible copper foil laminates can only be used in frequency bands below 10GHz and cannot work in the 28GHz band, which is a millimeter wave (mmwave) band. In addition, the polyimide (PI) film used as the base film has a problem of increased signal loss in a humid environment due to its high water absorption rate.

Next-Generation Mobile Network (NGMN), 5G mobile communications, and 6G mobile communications all use New Radio (NR) technology as the wireless access technology between terminals and base stations, using the 28GHz frequency band, which is a millimeter wave (mmwave) band, to quickly transmit large amounts of data.

Therefore, in order to use this millimeter wave (mmwave) band wireless communication, it is currently necessary to develop flexible copper foil laminates and flexible printed circuit boards that can be used in antennas, communication equipment, base station radars, server motherboards, etc.

Existing technical literature

Patent Literature

Korean patent No. 1275159

Korean patent No. 2334251

In order to solve the above problems, the purpose of the present invention is to provide the following flexible copper foil laminate and flexible printed circuit board, that is, without using an adhesive, copper foil can be directly plated on the composite material layer to achieve a low-roughness conductive layer.

Furthermore, another object of the present invention is to provide a flexible copper foil laminate and a flexible printed circuit board, that is, a fluorine-based composite material having lower capacitance and water absorption than polyimide is used to prepare the substrate layer, thereby reducing capacitance loss and signal loss by improving dimensional stability even in a humid environment.

Furthermore, another object of the present invention is to provide a flexible copper foil laminate and a flexible printed circuit board, which can be used in high-frequency wireless communication equipment because excellent signal transmission is achieved by minimizing capacitance loss and signal loss.

Furthermore, another object of the present invention is to provide a flexible copper foil laminate and a flexible printed circuit board, that is, a material layer with high tensile strength can be built into the composite material layer to achieve excellent peeling strength characteristics and frequency characteristics.

However, the technical objectives to be achieved by the embodiments of the present invention are not limited to the above technical objectives, and other technical objectives may also exist.

The flexible copper foil laminate for electronic panels of one embodiment of the present invention includes: a substrate layer, made of a flexible fluorine-based composite material; a composite material layer, formed on at least one side of the substrate layer, including a first material layer and a second material layer, the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive layer, formed on the composite material layer.

Preferably, in the composite material layer, the first material layer is stacked on the substrate layer, and the second material layer is stacked on the first material layer.

Preferably, in the composite material layer, the second material layer is stacked on the substrate layer, and the first material layer is stacked on the second material layer.

More preferably, the substrate layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

More preferably, the first material layer is made of liquid crystal polymer.

More preferably, the second material layer includes one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

More preferably, the conductive layer comprises one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc and tin.

More preferably, the surface roughness between the composite material layer and the conductive layer is 0.1μm~0.7μm.

More preferably, the first material layer is formed by a casting process.

More preferably, the second material layer is formed by a slit coating process.

The flexible printed circuit board of one embodiment of the present invention includes: a substrate layer, which is made of a flexible fluorine-based composite material; a composite material layer, which is formed on at least one side of the substrate layer, and includes a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive pattern layer, which is formed on the composite material layer.

Preferably, in the composite material layer, the first material layer is stacked on the base material layer, and the second material layer is stacked on the first material layer.

Preferably, in the composite material layer, the second material layer is stacked on the substrate layer, and the first material layer is stacked on the second material layer.

More preferably, the substrate layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

More preferably, the first material layer is made of liquid crystal polymer.

More preferably, the second material layer includes one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

More preferably, the conductive pattern layer comprises one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc and tin.

More preferably, the surface roughness between the composite material layer and the conductive pattern layer is 0.1μm~0.7μm.

More preferably, the first material layer is formed by a casting process.

More preferably, the second material layer is formed by a slit coating process.

The present invention has the following effect: without using an adhesive, a copper foil can be directly plated on a composite material layer to realize a low-roughness conductive layer.

Furthermore, in the present invention, since the substrate layer is prepared using a fluorine-based composite material having lower capacitance and water absorption than polyimide, capacitance loss and signal loss can be reduced by improving dimensional stability even in a humid environment.

Furthermore, the present invention can improve signal transmission rate in high-frequency applications such as 5G mobile communications by minimizing high-frequency signal loss.

Furthermore, the present invention can achieve excellent peeling strength characteristics and frequency characteristics by embedding a high tensile strength material layer in the composite material layer. Therefore, it can not only prevent the base material layer and the copper foil from peeling off, but also reduce the loss of high-frequency signals.

The effects of the present invention are not limited to the effects mentioned above. Ordinary technicians in the technical field to which the present invention belongs (referred to as "ordinary technicians") can clearly understand other effects not mentioned through the contents recorded in the scope of the invention patent application.

101: Flexible substrate film

102, 103: Adhesive

104, 105: Copper foil

210, 310: base material layer

220, 240, 320, 340: Composite material layer

221, 241, 322, 342: First material layer

222, 242, 321, 341: Second material layer

230, 250, 330, 350: conductive layer

A: Partial

Below, the embodiments of the present invention are described with reference to the attached drawings, wherein similar reference numerals represent similar structural elements, but are not limited thereto.

Figure 1 is a diagram showing an existing flexible copper foil laminate, part (a) is a cross-sectional structural diagram of the existing flexible copper foil laminate, and part (b) is an enlarged diagram of the joint surface "A" of the copper foil and the adhesive.

Figure 2 is a cross-sectional structural diagram of a flexible copper foil laminate for electronic panels according to an embodiment of the present invention.

Figure 3 is a cross-sectional structural diagram of a flexible copper foil laminate for electronic panels in another embodiment of the present invention.

The specific contents used to implement the present invention are described in detail below with reference to the attached drawings. However, in the following description, when there is a risk of unnecessarily confusing the main idea of the present invention, the specific description of the known functions or structures will be omitted.

In the accompanying drawings, the same or corresponding structural elements are given the same figure marks. In addition, in the following description of the embodiments, repeated descriptions of the same or corresponding structural elements will be omitted. However, even if the relevant structural elements are omitted, it cannot be said that the structural elements do not exist in any embodiment.

In the embodiments described in this specification, the advantages, features and implementation methods thereof can be clarified by referring to the embodiments described in conjunction with the attached drawings. However, the present invention is not limited to the embodiments disclosed below, and can be implemented through a variety of different implementation methods. Moreover, the embodiments of the present invention are only used for ordinary technical personnel in the technical field to which the present invention belongs to fully understand the scope of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary technicians in the technical field to which the present invention belongs. And, unless clearly defined, terms defined in commonly used dictionaries should not be interpreted as idealized or overly formalized meanings.

For example, the term "technology" refers to systems, methods, computer-readable instructions, modules, algorithms, hardware logic and/or operations permitted by the context of the above documents and as a whole.

In this specification, the terms used will be briefly described and the disclosed embodiments will be specifically described. In this specification, the terms used are selected as much as possible from the currently widely used general terms in consideration of the functions of the present invention, but this may change with the intentions, conventions or disclosure of new technologies of technical personnel in the relevant fields. In addition, in certain cases, the terms arbitrarily selected by the applicant may also be used. In this case, their meanings are described in detail in the corresponding description of the present invention. Therefore, in this specification, the terms used should be defined based on their meanings and the full text of the present invention, rather than simply by the term names.

In this specification, unless the context clearly specifies the singular, a singular expression may include a plural expression. Also, unless the context clearly specifies the plural, a plural expression may include a singular expression. In the entire text of this specification, when it is indicated that a certain part includes a certain structural element, unless there is a special record to the contrary, other structural elements may also be included, and other structural elements are not excluded.

In the present invention, terms such as "include", "comprises", etc. may indicate the existence of features, steps, tasks, elements and/or structural elements, and such terms do not exclude the existence of more than one other function, step, task, element, structural element and/or its combination.

In the present invention, when a specific structural element is "combined", "combined", "connected", "related" or "reacted" with any other structural element, it may represent the direct combination, combination, connection and/or correlation or reaction of the specific structural element with other structural elements, but it is not limited to this. For example, there may be more than one intermediate structural element between the specific structural element and other structural elements. Moreover, in the present invention, "and/or" may include at least a partial combination of each item in multiple enumerated items or multiple projects.

In the present invention, the terms "first" and "second" are used to distinguish one structural element from other structural elements, and such terms do not limit the above structural elements. For example, it can be used to specify that the "first" structural element and the "second" structural element are the same or similar structural elements.

Flexible copper foil laminate for electronic boards

Figure 2 is a cross-sectional structural diagram of a flexible copper foil laminate for electronic panels according to an embodiment of the present invention.

According to an embodiment of the present invention, the flexible copper foil laminate for electronic panels of the present invention includes: a substrate layer 210, which is made of a flexible fluorine-based composite material; composite material layers 220, 240, which are formed on at least one side of the substrate layer 210, including first material layers 221, 241 and second material layers 222, 242, the tensile strength of the first material layers 221, 241 is greater than that of the substrate layer 210, and the second material layers 222, 242 are made of a fluorine-based composite material; and conductive layers 230, 250, which are arranged on the composite material layers.

The thickness of the substrate layer 210 may be 20 μm to 30 μm. In the composite material layers 220 and 240, the thickness of the first material layers 221 and 241 may be 10 μm to 25 μm, and the thickness of the second material layers 222 and 242 may be 10 μm to 20 μm. The thickness of the conductive layers 230 and 250 may be 2 μm to 18 μm.

The substrate layer 210 may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). In the present invention, since the substrate layer 210 is prepared using a fluorine-based composite material having lower capacitance and water absorption than polyimide, capacitance loss can be reduced and dimensional stability can be improved.

The first material layers 221 and 241 are formed on the substrate layer 210 and can be made of liquid crystal polymer (LCP). The fluorine-based composite material constituting the substrate layer 210 has the disadvantage of being relatively prone to physical deformation such as bending and tearing. Liquid crystal polymer has the advantages of relatively low water absorption and thermal expansion coefficient and relatively high tensile strength. Therefore, in the present invention, as the first material layers 221 and 241 made of liquid crystal polymer are formed on the substrate layer 210, physical deformation of the substrate layer 210 can be prevented by improving rigidity. The first material layers 221 and 241 can be formed on the substrate layer 210 by a casting process.

The second material layers 222 and 242 are formed on the first material layers 221 and 241 and may be made of a fluorine-based composite material. As the second material layers 222 and 242 made of a fluorine-based composite material having a lower capacitance than liquid crystal polymer are formed on the first material layers 221 and 241, capacitance loss may be reduced. The second material layers 222 and 242 may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). The second material layers 222 and 242 may be formed on the first material layers 221 and 241 by a slit coating process.

The conductive layers 230 and 250 may include a conductive metal. Specifically, the conductive layers may include one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc, and tin. More specifically, the conductive layers 230 and 250 may be copper foils. The conductive layers 230 and 250 may be directly formed on the second material layers 222 and 242 by plating. Before plating, the surface of the second material layers 222 and 242 used for plating the conductive layers 230 and 250 may be pre-treated. The pre-treatment method may include plasma treatment, ion surface treatment, etc. This pre-treatment process can improve the adhesion between the deposited conductive layers 230, 250 and the second material layers 222, 242 to prevent the conductive layers 230, 250 from peeling off.

A seed layer (not shown) may be formed on the pretreated surface. The seed layer may be formed by electroless plating and sputtering. The metal used for the seed layer may include one or more metals selected from the group consisting of nickel, copper, chromium and titanium.

Conductive layers 230 and 250 may be plated on the composite material layers 220 and 240 or the seed layer. Conductive layers 230 and 250 may be formed by electroless plating or electrolytic plating of copper. Electrolytic plating may be achieved under the conditions of a current of 5ASD (Amp per decimeter2) and a voltage of 0.5V to 2V.

In the flexible copper foil laminate of the present invention, the surface roughness between the composite material layers 220, 240 and the conductive layers 230, 250 can be 0.1μm~0.7μm.

Figure 3 is a cross-sectional structural diagram of a flexible copper foil laminate for electronic panels in another embodiment of the present invention.

According to an embodiment of the present invention, the flexible copper foil laminate for electronic panels of the present invention includes: a substrate layer 310, which is made of a flexible fluorine-based composite material; composite material layers 320, 340, which are formed on at least one side of the substrate layer 310, including first material layers 322, 342 and second material layers 321, 341, the tensile strength of the first material layers 322, 342 is greater than that of the substrate layer, and the second material layers 321, 341 are made of a fluorine-based composite material; and conductive layers 330, 350, which are formed on the composite material layers.

The thickness of the substrate layer 310 may be 20 μm to 30 μm. In the composite material layers 320 and 340, the thickness of the first material layers 322 and 342 may be 10 μm to 25 μm, and the thickness of the second material layers 321 and 341 may be 10 μm to 20 μm. The thickness of the conductive layers 330 and 350 may be 2 μm to 18 μm.

The substrate layer 310 may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). In the present invention, since the substrate layer 310 is prepared using a fluorine-based composite material having lower capacitance and water absorption than polyimide, capacitance loss can be reduced and dimensional stability can be improved.

The second material layers 321 and 341 are formed on the base material layer 310 and may be made of a fluorine-based composite material. The second material layers 321 and 341 may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). The second material layers 321 and 341 may be formed on the base material layer 310 by a slit coating process.

The first material layers 322 and 342 are formed on the second material layers 321 and 341 and can be made of liquid crystal polymer (LCP). Liquid crystal polymer has the advantages of relatively low water absorption and thermal expansion coefficient and relatively high tensile strength. Therefore, in the present invention, as the first material layers 322 and 342 are formed between the second material layers 321 and 341 and the conductive layers 330 and 350, the structural stability of the conductive layers 330 and 350 can be improved.

The conductive layers 330 and 350 may include a conductive metal. Specifically, the conductive layers may include one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc, and tin. More specifically, the conductive layers 330 and 350 may be copper foils. The conductive layers 330 and 350 may be directly formed on the first material layers 322 and 342 by plating. Before plating, the surface of the first material layers 322 and 342 for plating the conductive layers 330 and 350 may be pre-treated. The pre-treatment method may include plasma treatment, ion surface treatment, etc. This pre-treatment process can improve the adhesion between the deposited conductive layers 330, 350 and the first material layers 322, 342 to prevent the conductive layers 330, 350 from peeling off.

A seed layer (not shown) may be formed on the pretreated surface. The seed layer may be formed by electroless plating and sputtering. The metal used for the seed layer may include one or more metals selected from the group consisting of nickel, copper, chromium and titanium.

Conductive layers 330 and 350 may be plated on the composite material layers 320 and 340 or the seed layer. Conductive layers 330 and 350 may be formed by electroless plating or electrolytic plating of copper. Electrolytic plating may be achieved under the conditions of a current of 5ASD (Amp per decimeter2) and a voltage of 0.5V to 2V.

In the flexible copper foil laminate of the present invention, the surface roughness between the composite material layers 320, 340 and the conductive layers 330, 350 can be 0.1μm~0.7μm.

Flexible printed circuit board

The flexible printed circuit board of an example of the present invention includes: a substrate layer, which is made of a flexible fluorine-based composite material; a composite material layer, which is formed on at least one side of the substrate layer, and includes a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive pattern layer, which is formed on the composite material layer. In the composite material layer, the first material layer can be stacked on the substrate layer and then the second material layer can be stacked, and the first material layer can be stacked on the substrate layer and then the second material layer can be stacked.

The thickness of the substrate layer can be 20μm~30μm. In the composite material layer, the thickness of the first material layer can be 10μm~25μm, and the thickness of the second material layer can be 10μm~20μm. The thickness of the conductive pattern layer can be 2μm~18μm.

The substrate layer may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

The first material layer can be formed on the substrate layer or the second material layer, and can be made of liquid crystal polymer (LCP) and can be formed by a casting process.

The second material layer may be formed on the substrate layer or the first material layer, may be made of a fluorine-based composite material, and may be formed by a slit coating process. The second material layer may include at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA).

The conductive pattern layer may include a conductive substance. For example, the conductive pattern may include a conductive metal. Specifically, the conductive pattern may include one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc, and tin. More specifically, the conductive pattern may include a copper pattern.

The shape of the conductive pattern is not particularly limited, and may include, for example, a line pattern or a planar spiral pattern.

Furthermore, the conductive pattern layer may include a circuit pattern. More specifically, the conductive pattern layer may include a printed circuit pattern.

Furthermore, the conductive pattern layer may include a terminal pattern. The terminal pattern may be electrically connected to an external circuit.

Furthermore, the electronic board may also include through holes that penetrate the substrate film layer along the thickness direction for electrically connecting the conductive pattern.

After the conductive layer is directly deposited on the composite material layer, a pattern can be formed on the conductive layer to form a conductive pattern layer.

In the flexible printed circuit board of the present invention, the surface roughness between the composite material layer and the conductive pattern layer is 0.1μm~0.7μm.

The above description of the present invention is only an example. Without changing the technical idea or essential features of the present invention, ordinary technicians in the technical field to which the present invention belongs can easily change the present invention through other implementation methods. Therefore, the embodiments described above are only examples in all aspects and should not be understood as limiting. For example, the various structural elements of a single structure can be implemented in a dispersed manner, and similarly, the dispersed structural elements can also be implemented in combination.

Compared with the above detailed description, the scope of the present invention should be expressed based on the scope of the invention application patent. All changes or variant implementations derived from the meaning, scope and equivalent concepts of the invention application patent scope belong to the scope of the present invention.

210: substrate layer 220, 240: composite material layer 221, 241: first material layer 222, 242: second material layer 230, 250: conductive layer

Claims (18)

A flexible copper foil laminate for electronic panels, comprising: a substrate layer made of a flexible fluorine-based composite material; a composite material layer formed on at least one side of the substrate layer, comprising a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive layer formed on the composite material layer, wherein the first material layer is stacked on the substrate layer, and the second material layer is stacked on the first material layer, and the first material layer is made of a liquid crystal polymer. A flexible copper foil laminate for electronic panels, comprising: a substrate layer made of a flexible fluorine-based composite material; a composite material layer formed on at least one side of the substrate layer, comprising a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive layer formed on the composite material layer, wherein the second material layer is stacked on the substrate layer, and the first material layer is stacked on the second material layer, and the first material layer is made of a liquid crystal polymer. A flexible copper foil laminate for electronic boards as claimed in claim 1 or 2, wherein: the thickness of the substrate layer is 20-30 μm, the thickness of the first material layer is 10-25 μm, the thickness of the second material layer is 10-20 μm. A flexible copper foil laminate for an electronic board as claimed in claim 1 or 2, wherein the substrate layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). A flexible copper foil laminate for an electronic board as claimed in claim 1 or 2, wherein the second material layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). A flexible copper foil laminate for an electronic board as claimed in claim 1 or 2, wherein the conductive layer comprises one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc and tin. A flexible copper foil laminate for electronic panels as claimed in claim 1 or 2, wherein the surface roughness between the composite material layer and the conductive layer is 0.1 μm to 0.7 μm. A flexible copper foil laminate for electronic boards as claimed in claim 1 or 2, wherein the first material layer is formed by a casting process. A flexible copper foil laminate for electronic boards as claimed in claim 1 or 2, wherein the second material layer is formed by a slit coating process. A flexible printed circuit board, comprising: a substrate layer made of a flexible fluorine-based composite material; a composite material layer formed on at least one side of the substrate layer, comprising a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive pattern layer formed on the composite material layer, wherein the first material layer is stacked on the substrate layer, and the second material layer is stacked on the first material layer, and the first material layer is made of a liquid crystal polymer. A flexible printed circuit board, comprising: a substrate layer made of a flexible fluorine-based composite material; a composite material layer formed on at least one side of the substrate layer, comprising a first material layer and a second material layer, wherein the tensile strength of the first material layer is greater than that of the substrate layer, and the second material layer is made of a fluorine-based composite material; and a conductive pattern layer formed on the composite material layer, wherein the second material layer is stacked on the substrate layer, and the first material layer is stacked on the second material layer, and the first material layer is made of a liquid crystal polymer. A flexible printed circuit board as claimed in claim 10 or 11, wherein: the thickness of the substrate layer is 20-30 μm, the thickness of the first material layer is 10-25 μm, the thickness of the second material layer is 10-20 μm. A flexible printed circuit board as claimed in claim 10 or 11, wherein the substrate layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). A flexible printed circuit board as claimed in claim 10 or 11, wherein the second material layer comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA). A flexible printed circuit board as claimed in claim 10 or 11, wherein the conductive pattern layer comprises one or more metals selected from the group consisting of copper, nickel, gold, silver, zinc and tin. As in claim 10 or 11, the surface roughness between the composite material layer and the conductive pattern layer is 0.1 μm to 0.7 μm. A flexible printed circuit board as claimed in claim 10 or 11, wherein the first material layer is formed by a casting process. A flexible printed circuit board as claimed in claim 10 or 11, wherein the second material layer is formed by a slit coating process.

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