WO2014092343A1

WO2014092343A1 - Functional film, and flexible printed circuit board including same

Info

Publication number: WO2014092343A1
Application number: PCT/KR2013/010060
Authority: WO
Inventors: 남광현
Original assignee: Nam Kwang Hyun
Priority date: 2012-12-10
Filing date: 2013-11-07
Publication date: 2014-06-19
Also published as: KR20140074700A; KR101438743B1

Abstract

The present invention relates to a functional film having an electromagnetic wave shielding function. The functional film comprises: an insulating layer; a primer layer formed on the insulating layer; a conductive layer formed on the primer layer; and an adhesive layer formed on the conductive layer, wherein the primer layer may be conductive.

Description

Functional film and flexible circuit board including same

The present application relates to a functional film and a flexible circuit board including the same.

In recent years, the demand for flexible printed circuit boards (FPCBs) is increasing in small wireless device circuits such as mobile phones, DMB terminals, and PDAs, coupled with the explosive growth of the wireless communication environment and the high integration and precision of electronic devices.

Each of the components attached to the flexible circuit board uses different frequencies. At this time, each component generates electromagnetic waves, and these electromagnetic waves interfere with each other, causing electromagnetic interference, causing malfunction, noise, and bleeding of the LCD screen, and the distance between components due to high integration due to the miniaturization tendency of the circuit. As they get closer, these disorders are becoming more frequent than ever.

In order to prevent such a problem, there are largely a method of attaching a conductive film to the flexible circuit board and a method of printing and curing the conductive paste on top of the circuit.

However, when using these methods, there is a disadvantage in that the flexibility of the conductive film and the conductive paste is reduced, so that cracks are generated at the bent portion of the flexible circuit board, so that the conductivity is reduced and the electromagnetic wave blocking performance is reduced. In addition, the method of using a conductive paste has a disadvantage in that it is cumbersome because a separate protective coating is to be printed after printing it on the upper part of the circuit.

Due to such disadvantages, the conventional method could not sufficiently solve the problems caused by the electromagnetic waves generated in the flexible circuit board.

An object of the present invention is to provide a functional film capable of preventing malfunction and smearing of a liquid crystal screen by effectively blocking the electromagnetic waves generated from the components attached to the circuit board of the flexible circuit board by improving flexibility.

As a technical means for achieving the above technical problem, the functional film according to the first aspect of the present application, the insulating layer; A primer layer formed on the insulating layer; A conductive layer formed on the primer layer; And an adhesive layer formed on the conductive layer, wherein the primer layer may be conductive.

On the other hand, the flexible circuit board according to the second aspect of the present application, including the functional film according to the first aspect of the present application, the upper side may be provided so that the adhesive layer abuts.

On the other hand, the manufacturing method of the functional film according to the third aspect of the present invention, the manufacturing method of the functional film of the first aspect of the present application, forming the primer layer on the insulating layer; Forming the conductive layer on the primer layer; It may include the step of forming the adhesive layer on the conductive layer.

According to the above-described problem solving means of the present invention, the functional film comprises a primer layer containing a conductive material, thereby improving the surface resistance value to increase the electromagnetic shielding efficiency, cracks occur in the conductive layer at the bent portion of the flexible circuit board In addition, the primer layer serves as a bridge can effectively shield the electromagnetic waves.

1 is a conceptual diagram showing a functional film according to an embodiment of the present application.

2 is a conceptual diagram illustrating a flexible circuit board according to an embodiment of the present disclosure.

3 is a conceptual diagram illustrating a tensile force applied to a functional film when a functional film according to an embodiment of the present application is attached to a flexible circuit board.

Figure 4 is a flow chart showing a method of manufacturing a functional film according to an embodiment of the present application.

5 to 9 is a view schematically showing a manufacturing process of a functional film according to an embodiment of the present application.

10 compares the surface resistance according to the tensile rate of the functional film according to an embodiment of the present application and the functional film according to Comparative Examples 1 and 2.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present disclosure. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

Throughout this specification, when a member is located “on” another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

Throughout this specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding the other components unless specifically stated otherwise. As used throughout this specification, the terms "about", "substantially" and the like are used at, or in the sense of, numerical values when a manufacturing and material tolerance inherent in the stated meanings is indicated, Accurate or absolute figures are used to assist in the prevention of unfair use by unscrupulous infringers. As used throughout this specification, the term "step to" or "step of" does not mean "step for."

Throughout this specification, the term “combination of these” included in the expression of the makushi form means one or more mixtures or combinations selected from the group consisting of constituents described in the expression of the makushi form, wherein the constituents It means to include one or more selected from the group consisting of.

For reference, in the description of the embodiments of the present application, terms related to directions or positions (upper side, lower side, and the like) are set based on the arrangement state of each component shown in the drawings. For example, as seen in FIG. 1, the upper side may be the upper side, the lower side may be the lower side, and the like. However, in various practical applications of the embodiments of the present application, the upper side and the lower side may be arranged in various directions such as being reversed.

Hereinafter, with reference to the accompanying drawings will be described in detail the present application.

First, the functional film 1 (hereinafter referred to as 'the present functional film') according to an embodiment of the present application will be described.

Electromagnetic waves generated from components attached to the flexible circuit board 3 affect different components, causing malfunctions and smearing of the LCD screen. Therefore, in order to prevent these problems, a functional film having an electromagnetic shielding function is attached on the circuit board.

In this case, the medium made of metal has a property of reflecting all light, and the functional film blocks most of the electromagnetic waves by blocking most of the electromagnetic waves by reflecting most of the electromagnetic waves through the layer made of these metallic components. Therefore, the functional film has a high electrical conductivity, the better the shielding function of the electromagnetic wave is formed of a material having a very low impedance.

The present functional film 1 includes an insulating layer 10.

The functional film 1 is attached to the flexible circuit board 3 through thermal compression. At this time, the press bonding process is performed at a high temperature of about 170 ℃ to about 180 ℃, the lead-free soldering process of the surface mounting process (SMT process) is performed at a high temperature of about 250 ℃ to about 270 ℃, primer layer 30 In order to protect the conductive layer 50 and the adhesive layer 70, the insulating layer 10 is provided. Therefore, the insulating layer 10 is preferably made of a material having good heat resistance.

For example, the insulating layer 10 may include polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), polycarbonate (PC), and the like, and preferably other It may include polyimide (PI) having better heat resistance than the material.

For example, the insulating layer 10 may have a thickness of 12 μm.

The present functional film 1 includes a primer layer 30.

The primer layer 30 is formed on the insulating layer 10.

The primer layer 30 is conductive.

The functional film 1 is attached onto the flexible circuit board 3 through heating / pressurization. At this time, referring to Figure 3, the tensile force is applied to the conductive layer 50 to be described later to the bent portion due to the component on the substrate in the direction shown in Figure 3, the heating temperature is raised to 280 ℃ to 300 ℃, Cracks may occur in the conductive layer 50. When a crack is generated in the conductive layer 50, electromagnetic waves are escaped through the cracks, thereby degrading the electromagnetic shielding effect.

In addition, when attaching on the flexible circuit board 3 by heating / pressing the functional film 1, if the amount of pressure applied is lowered, the functional film 1 cannot be in close contact with the flexible circuit board 3, Electromagnetic waves may affect other components.

Thus, the conductive primer layer 30 formed between the insulating layer 10 and the conductive layer 50 serves as a bridge to block the electromagnetic wave that escapes between the cracks of the conductive layer 50, thereby improving the surface resistance value electromagnetic waves Can be effectively blocked.

The primer layer 30 may include a fine structure having conductivity.

The microstructure is preferably formed of a material having high conductivity in order to effectively block the electromagnetic wave that escapes between the cracks of the conductive layer 50.

For example, the microstructure may include any one or more of silver (Ag), copper (Cu), and nickel (Ni). However, the present invention is not limited thereto, and the microstructure may be formed of various metal materials having high conductivity.

The microstructures may have the form of flakes or wires.

In the case of having such a shape, since the microstructure may be disposed over a wider range with respect to the surface direction in which the primer layer 30 is formed, the electromagnetic wave may be more effectively blocked.

For example, the microstructures may be silver nanowires.

The microstructures may be conductive carbon.

At this time, the microstructure is preferably carbon nanotubes (CNT) having excellent physical properties compared to the unit price. However, the present invention is not limited thereto, and the microstructure may be graphene or the like.

The primer layer 30 may include a primer base layer 31.

As described above, referring to FIG. 3, when the functional film 1 is attached onto the flexible circuit board 3, the functional film 1 is subjected to a tensile force due to a bending part due to a component on the substrate, and thus, the tensile force may be reduced. The primer base layer 31 is preferably made of a flexible material so as not to be broken by the material. Through this, the flexibility of the functional film 1 can be improved.

For example, the primer base layer 31 may include a polyester resin, an epoxy resin, a polyurethane resin, or the like.

In addition, the primer base layer 31 may be a modified polyester (epester) resin or epoxy (epoxy) resin. When the primer base layer 31 contains such a modified resin, flexibility becomes more excellent, and thus the flexibility of the functional film 1 can be further improved.

In addition, the primer layer 30 may be formed on the primer base layer 31, and may include a primer conductive layer 33 including a microstructure.

As described above, the primer conductive layer 33 may block the electromagnetic wave escaping through the crack of the conductive layer 50, so that the functional film 1 having a better electromagnetic shielding function may be realized.

At this time, it is preferable that the microstructures are evenly dispersed in the primer conductive layer 33 as evenly as possible.

The primer conductive layer 33 may include the nanostructured microstructure and the conductive carbon microstructure at the same time, or may include only one of the nanostructured microstructure or the conductive carbon microstructure.

The primer layer 30 may have a thickness of 0.02 μm or more and 10 μm or less.

When the thickness of the primer layer 30 is less than 0.02 μm, the portion having conductivity is too small so that the primer layer 30 may have a conductivity enough to shield the electromagnetic waves from escaping through the crack of the conductive layer 50. none.

In addition, when the thickness of the primer layer 30 exceeds 10 μm, since the rigidity of the primer layer 30 is increased and flexibility is reduced, the degree of being pressed onto the flexible circuit board 3 when the functional film 1 is attached is increased. It can be degraded and electromagnetic waves can affect each other between components on the substrate. Therefore, problems such as malfunction, screen blur, and the like cannot be effectively prevented.

In addition, the primer layer 30 may have an elongation of 30% or more and 200% or less.

When the elongation of the primer layer 30 is less than 30%, cracks may occur in the process of attaching the functional film 1 due to poor flexibility, and the adhesion with the flexible circuit board 3 may be inferior.

In addition, when thermally compressing the functional film 1, the primer layer 30 may be protected from the high temperature by the insulating layer 10, but complete heat shielding is impossible, and thus the primer layer 30 itself may be somewhat heat resistant. Need to have In addition, in order to form the primer layer 30 having an elongation of more than 200%, the primer layer 30 should include a much larger amount of rubber compared to the amount of the epoxy resin, which is the primer layer 30 Heat resistance is inferior. Accordingly, it is not possible to withstand the lead-free soldering process in the press crimping process at a high temperature of about 170 ° C to about 180 ° C and the SMT process at a high temperature of about 250 ° C to about 270 ° C. In addition, since the primer layer 30 is formed too soft, the primer layer 30 may melt and leak to the side at a high temperature.

Therefore, when the elongation is 30% or more and 200% or less, the primer layer 30 may have cracking resistance and heat resistance to withstand high-temperature processes and flexibility to be in close contact with the flexible circuit board 3. Preferably, the primer layer 30 is formed to have an elongation of 50% or more and 150% or less, thereby ensuring optimal heat resistance and flexibility.

The color of the primer layer 30 may be a color having low brightness. For example, the primer layer 30 may be black.

The present functional film 1 includes a conductive layer 50.

As described above, the conductive layer 50 is preferably made of a material having a low electrical resistance so that the electromagnetic wave generated in the component can be converted into the surface current to flow on the surface of the conductive layer 50.

The conductive layer 50 is formed on the primer layer 30.

The conductive layer 50 has high electrical conductivity but may be inferior in flexibility. Therefore, in the process of attaching the functional film 1 to the flexible circuit board 3 by being pressed / heated, cracks may be generated in the conductive layer 50, and electromagnetic waves may escape through the cracks, thereby affecting other components. Can give

Thus, by forming the primer layer 30 on the lower portion of the conductive layer 50, by blocking the electromagnetic waves exiting between the cracks formed in the conductive layer 50, it is possible to effectively prevent the occurrence of the problem that the electromagnetic waves between the components affect each other. Can be.

In addition, a cracking phenomenon of the conductive wire 50 may be prevented by the primer layer 30 having high flexibility.

For example, the conductive layer 50 may include silver (Ag). In general, the conductive layer 50 is formed by depositing on the primer layer 30. In this case, the conductive layer 50 may be formed through the cheapest process when deposited with silver (Ag).

In addition, the conductive layer 50 may include copper (Cu), nickel (Ni), and aluminum (Al). In addition, the conductive layer 50 may include a highly conductive material.

For example, the conductive layer 50 may be formed by silver deposition to a thickness of 800 kPa.

The present functional film 1 includes an adhesive layer 70.

The adhesive layer 70 is formed on the conductive layer 50.

Referring to FIG. 2, the adhesive layer 70 is attached to the flexible circuit board 3 and is preferably made of a material having excellent adhesive ability. For example, the adhesive layer 70 may include an epoxy resin or a polyester resin. The adhesive layer 70 made of such a material may have excellent adhesive ability as compared with that made of polyether resin.

The adhesive layer 70 may include conductive particles 71.

Through this, the adhesive layer 70 may have anisotropic conductivity. Therefore, when the functional film 1 is attached on the flexible circuit board 3, the circuit and the conductive layer 50 can be electrically connected to each other, and can be electrically insulated between adjacent components.

In this case, the conductive particles 71 may mean not only spherical particles but also particles formed in a wire, plate, or the like form.

The conductive particles 71 may include at least one of silver (Ag), copper (Cu), nickel (Ni), and silver (Ag) coated copper (Cu).

The conductive particles 71 preferably have excellent conductivity so that the circuit and the conductive layer 50 can be electrically connected to each other. In particular, when the conductive particles 71 include silver coated copper coated with silver having low reactivity to copper having high conductivity, high conductivity and chemical stability may be secured at the same time.

The functional film 1 may include a protective film 90.

The protective film 90 may be formed under the insulating layer 10.

The protective film 90 may serve to protect the damage before the functional film 1 is attached onto the flexible circuit board 3.

In addition, the protective film 90 may include a release layer on the upper side.

Through this, after the functional film 1 is attached on the flexible circuit board 3, the protective film 90 can be removed.

FIG. 10 compares the surface resistance values according to the tensile test of the examples of the functional film 1 and the functional films of Comparative Examples 1 and 2. FIG.

In the exemplary embodiment, the conductive primer layer 30 is formed by coating the conductive primer layer 30 to a thickness of 3 μm on a 12 μm thick insulating layer 10 including polyimide, and then, silver is deposited on the conductive layer to conduct a thickness of 800 μm. The layer 50 is formed. Here, the primer layer 30 includes 30% by weight of a phenol-modified epoxy resin and 10% by weight of polyester resin, 2% by weight of phthalic anhydride as a curing agent, and 53% by weight of methylethylketone as a solvent. As the conductive microstructure, 2 wt% of silver nanowires having an average particle diameter of 100 nm and an average length of 50 μm and 3 wt% of conductive carbon are formed.

At this time, YDPN 644 of Kukdo Chemical was used for phenol-modified epoxy resin, Vylon 550 of Toyobo Co., Ltd. was used, and acid anhydride curing agent MNA of Kukdo Chemical was used for polyester resin. In addition, silver nanowires were used a100 grade of KEC Tech, conductive carbon was used Ketjenblack 300 grade of Pyung Hwa Chemical, and the insulating layer 10 containing polyimide was used LN grade of SKkolon.

On the other hand, in Comparative Example 1, the primer layer does not include the conductive microstructures included in the above-described embodiment, and in Comparative Example 2, the primer layer itself of the above-described embodiment is not included, and the rest are all examples. Are formed under the same conditions as.

Each of Examples, Comparative Examples 1 and 2 formed as described above was fabricated in 50 mm X 80 mm specimens, and each surface resistance was measured using a Mitsubishi surface resistance meter by tensioning 30% and 50%, respectively, with an Instron universal strength. It was measured (JISK 7194 test method).

When comparing the results of the tensile test of the Examples, Comparative Examples 1 and 2 produced by the above components and forms are as follows.

First, comparing the present functional film (1) containing the conductive primer layer 30 and Comparative Example 1 including the non-conductive primer layer, the present functional film (1) at 30% and 50% tension Although the surface resistance of is still low and little change, it can be seen that in Comparative Example 1 the surface resistance is significantly increased. Therefore, it can be seen that the present functional film 1 having the conductive primer layer 30 is excellent in electromagnetic wave shielding effect.

In addition, when comparing the present functional film 1 with the primer layer 30 and Comparative Example 2 without the primer layer, the functional film 1 is secured by the primer layer 30 at the time of stretching Although not broken, Comparative Example 2 has no flexibility and can be seen to be disconnected at 50% tensile strength. Therefore, it can be seen that the present functional film 1 having the primer layer 30 is excellent in flexibility and can be attached to the flexible printed circuit board 3 provided with various components without damage.

On the other hand, the flexible circuit board 3 (hereinafter referred to as "the flexible circuit board") according to an embodiment of the present application will be described. However, the same reference numerals are used for the same or similar components as those described in the functional film 1 according to an embodiment of the present invention, and the overlapping description will be briefly or omitted.

The flexible printed circuit board 3 includes the present functional film 1.

As a result, the flexible circuit board 3 may effectively shield electromagnetic waves generated from components, such that malfunction, noise, and screen bleeding may not occur.

In addition, the flexible circuit board 3 may have excellent flexibility and sliding resistance.

At this time, the adhesive layer 70 abuts on the upper side of the flexible printed circuit board 3.

As shown in FIG. 2, the functional film 1 may be bonded such that the adhesive layer 70 abuts on the flexible circuit board 3. In this case, when the adhesive layer 70 includes the conductive particles 71, electromagnetic waves may be shielded by energizing the circuit and the conductive layer 50.

On the other hand, a method of manufacturing a functional film according to an embodiment of the present application (hereinafter referred to as "manufacturing method of the functional film") will be described. However, the same reference numerals are used for the same or similar components as those described in the functional film 1 according to an embodiment of the present invention, and the overlapping description will be briefly or omitted.

The manufacturing method of the present functional film includes forming a primer layer 30 on the insulating layer 10 (S100).

In this case, the insulating layer 10 may include polyimide, and may be formed to have a thickness of 12 μm.

As described above, the primer layer 30 has a conductivity, serves as a bridge to block the electromagnetic waves exiting between the cracks of the conductive layer 50 so that the electromagnetic waves can be effectively blocked.

Referring to FIG. 6, the forming of the primer layer 30 (S100) may include forming the primer base layer 31 on the insulating layer 10 (S110).

Referring to FIG. 3, the functional film 1 is subjected to a tensile force at a bent portion due to a component on the substrate, wherein the primer base layer 31 is preferably made of a flexible material so as not to be damaged by the tensile force.

For example, the primer base layer 31 may include a polyester resin, an epoxy resin, a polyurethane resin, or the like, and may include a material in which a polyester resin or an epoxy resin is modified. It is preferable to.

In addition, referring to FIG. 7, the forming of the primer layer 30 (S100) may include coating the solvent in which the conductive microstructure is dispersed on the primer base layer 31 (S120). .

As described above, the primer layer 30 has conductivity by the primer conductive layer 33, thereby preventing electromagnetic waves from escaping through the crack of the conductive layer 50.

By coating the solvent in which the microstructures are dispersed to form the primer conductive layer 33, the microstructures may be evenly distributed on the primer base layer 31 to improve the electromagnetic shielding effect.

In step S100 of forming the primer layer 30, the primer layer 30 may have a thickness of 0.02 μm or more and 10 μm or less.

As described above, when the thickness of the primer layer 30 is less than 0.02 μm, since the conductivity of the primer layer 30 is lowered, it may effectively serve as a bridge that shields electromagnetic waves emitted through the crack of the conductive layer 50. none.

In addition, in the step (S100) of forming the primer layer 30, the primer layer 30 may have an elongation of 30% or more and 200% or less.

As described above, when the elongation of the primer layer 30 is less than 30%, flexibility may be degraded, and cracks may occur when the functional film 1 is attached, and adhesion to the flexible circuit board 3 may be inferior.

In addition, in order to form the primer layer 30 having an elongation of more than 200%, the primer layer 30 should include a much larger amount of rubber compared to the amount of the epoxy resin. Since the primer layer 30 is inferior in heat resistance, the primer layer 30 cannot withstand the press crimping process at a high temperature of about 170 ° C to about 180 ° C and the lead-free soldering process of the SMT process at a high temperature of about 250 ° C to about 270 ° C. In addition, since the primer layer 30 is formed too soft, the primer layer 30 may melt and leak to the side at a high temperature.

The manufacturing method of the present functional film includes a step S200 of forming the conductive layer 50 on the primer layer 30 (see FIG. 8).

For example, the conductive layer 50 may include silver (Ag), copper (Cu), nickel (Ni), and aluminum (Al). In addition, the conductive layer 50 may include a highly conductive material.

In the forming of the conductive layer 50 (S200), the conductive layer 50 may be sputter deposited on the primer layer 30.

In this case, when the conductive layer 50 is formed by sputtering deposition of silver (Ag), it may be formed through the cheapest process.

For example, the conductive layer 50 may be formed to have a thickness of 800 kPa through silver deposition.

The manufacturing method of the present functional film includes a step S300 of forming an adhesive layer 70 on the conductive layer 50 (see FIG. 9).

As described above, the adhesive layer 70 is a part attached to the flexible circuit board 3, and a material having excellent adhesion, for example, the adhesive layer 70 may be an epoxy resin or polyester. ) May include a resin.

In addition, the adhesive layer 70 may include the conductive particles 71 to have anisotropic conductivity so that the circuit and the conductive layer 50 may be energized with each other. In this case, the conductive particles 71 may include, for example, any one or more of silver (Ag), copper (Cu), nickel (Ni), and silver (Ag) coated copper (Cu). .

Since the functional film 1 includes the primer layer 30, electromagnetic waves emitted between the cracks of the conductive layer 50 generated when the functional film 1 is attached to the flexible circuit board 3 through heating / pressurization of the functional film 1 may be formed. It can effectively block. Therefore, it is possible to solve the electromagnetic interference problems such as malfunction, noise, screen blur.

The above description of the present application is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above description, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present application.

Claims

In the functional film,

Insulating layer;

A primer layer formed on the insulating layer;

A conductive layer formed on the primer layer; And

Including an adhesive layer formed on the conductive layer,

The primer layer is a functional film having conductivity.
The method of claim 1,

The primer layer is a functional film comprising a fine structure having conductivity.
The method of claim 2,

The fine structure is a functional film containing any one or more of silver (Ag), copper (Cu) and nickel (Ni).
The method of claim 3, wherein

The fine structure is a functional film having a flake or wire (wire) form.
The method of claim 2,

The fine structure is a functional film that is conductive carbon (carbon).
The method of claim 5,

The microstructure is a carbon nanotube (carbon nanotube, CNT) is a functional film.
The method of claim 2,

The primer layer,

Primer base layer; And

A functional film formed on the primer base layer, comprising a primer conductive layer containing the microstructure.
The method of claim 7, wherein

And the microstructures are dispersed and disposed within the primer conductive layer.
The method of claim 7, wherein

The primer base layer is a functional film is a polyester (epester) resin or epoxy (epoxy) resin is modified.
The method of claim 1,

The primer layer has a thickness of 0.02 ㎛ or more and less than 10 ㎛ functional film.
The method of claim 1,

The primer layer has an elongation of 30% or more and less than 200% functional film.
The method of claim 1,

The color of the primer layer is a functional film of low brightness.
The method of claim 1,

The conductive layer is a functional film containing silver (Ag).
The method of claim 1,

The insulating layer is a functional film containing polyimide (poly imide, PI).
The method of claim 1,

The adhesive layer is a functional film containing conductive particles.
The method of claim 15,

The conductive particles include any one or more of silver (Ag), copper (Cu), nickel (Ni), and silver (Ag) coated copper (Cu).
The method of claim 1,

Functional film further comprising a protective film formed on the lower side of the insulating layer.
The method of claim 17,

The protective film is a functional film comprising a release layer on the upper side.
In the flexible circuit board,

Including a functional film according to claim 1,

The upper side is a flexible circuit board is provided so that the adhesive layer abuts.
In the manufacturing method of the functional film according to claim 1,

Forming the primer layer on the insulating layer;

Forming the conductive layer on the primer layer;

Forming the adhesive layer on the conductive layer.
The method of claim 20,

Forming the primer layer,

Forming a primer base layer on the insulating layer; And

Coating a solvent in which a conductive microstructure is dispersed on the primer base layer.
The method of claim 20,

In the forming of the conductive layer,

The conductive layer is a method for producing a functional film is silver (Ag) sputter deposited on the primer layer.
The method of claim 20,

In the forming of the primer layer,

The primer layer has a thickness of 0.02 ㎛ or more and is formed in 10 ㎛ or less.
The method of claim 20,

In the forming of the primer layer,

The primer layer has an elongation of 30% or more and is formed in a functional film of less than 200%.