KR101361533B1 - Method for manufacturing electromagnetic wave shield film - Google Patents

Abstract

The present invention relates to an electromagnetic wave shielding film and an electromagnetic wave shielding film manufacturing method for reducing or not destroying a metal layer breaking rate, excellent wear resistance and blocking resistance, and reducing or breaking a breakdown rate at a high level.
The electromagnetic wave shielding film may include: an insulating layer having a carrier film attached to one surface thereof, a metal layer formed by coating and drying a metal ink on an upper surface of the insulating layer; and an electroconductive formed by coating and drying a conductive adhesive composition on the metal layer. In the electromagnetic shielding film comprising an adhesive layer (Conductive Adhesive layer), The insulating layer is composed of a polyimide film,
One side of a flexible printed circuit board (FPCB) that has excellent adhesion, heat resistance, electrical conductivity, flexibility, wear resistance, and flame retardancy, and requires high flexibility, high adhesion, and high heat resistance. It can be reliably applied to both sides, thereby providing an effect of effectively attenuating various electromagnetic waves generated in the substrate circuit.

Description

Electromagnetic wave shielding film manufacturing method {METHOD FOR MANUFACTURING ELECTROMAGNETIC WAVE SHIELD FILM}

The present invention relates to a method for producing an electromagnetic wave shielding film which reduces or does not destroy a metal layer breakage rate, has excellent wear resistance and blocking resistance, and does not reduce or break down at a high step.

Recently, the trend of light and short reduction of portable electronic devices for display and mobile devices is rapidly progressed, signal transmission speed between components in devices is increased, and signal interference due to occurrence of electromagnetic noise between adjacent circuits as circuit boards become high-density microcircuits. (EMI, Electromagnetic Interference) damage is on the rise.

In order to effectively block such electromagnetic waves, it is necessary to enclose the substrate circuit in a conductive film having excellent electrical conductivity, and to devise the electromagnetic waves generated therein to be attenuated through the conductor. In general, a metal thin film such as aluminum foil or silver foil having high conductivity is used. Or a conductive adhesive film prepared by dispersing the conductive powder in a binder resin, or uniformly applying the conductive paste to the surface of the circuit board, or forming a conductive paste into a film and heating it, has been applied.

Particularly, flexible printed circuit boards requiring repeated bending characteristics have limitations in use due to poor bending characteristics in metal thin films or liquid paste paints, and have good heat adhesiveness in applications requiring excellent bending characteristics. The demand for the product of the adhesive film shape excellent in conductivity is increasing.

As a conventional electromagnetic wave shielding adhesive film, a reinforcing shielding film having a conductive adhesive layer on one side of the cover film and a shielding layer of a metal thin film layer, if necessary, and a conductive adhesive layer and a releasable reinforcement film sequentially stacked on the other surface are known. (Japanese Patent Laid-Open No. 2003-298285).

Further, a shielding film having a shielding layer having a conductive adhesive layer or a metal thin film and a base film made of an aromatic polyamide resin is also known (Japanese Patent Laid-Open No. 2004-273577).

However, the cover film used for the shielding film is often made of engineering plastics such as polyphenylene sulfide (PPS), polyester, and aromatic aramid, and the thickness of the cover film is thick ( For example, 9 micrometers) rigidity is large.

For this reason, the flex resistance of the cover film is lowered.

The present invention is to solve the problems of the prior art described above, in addition to sufficient electromagnetic shielding properties, has excellent bending resistance and heat resistance to withstand high temperatures during lead-free solder reflow, and is attached to a flexible printed wiring board to shield electromagnetic noise The main object of the present invention is to provide a method for producing an electromagnetic wave shielding film that can be suitably used for a purpose.

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The present invention is a means for achieving the above object, an insulating layer with a carrier film, a metal layer formed by coating and drying a metal ink on the upper surface of the insulating layer, and a coating coating and drying a conductive adhesive composition on top of the metal layer An electromagnetic wave shielding film comprising: a conductive adhesive layer (Conductive Adhesive layer) formed, the insulating layer provides an electromagnetic shielding film, characterized in that made of a polyimide film.

At this time, the polyimide film is a mixture of 4,4'-oxydianiline (ODA) and p-phenylene diamine (PDA) and dianhydrides as diamines and pyromellitic dianhydrides (PMDA) and 3,3 '. A mixture of, 4,4'-biphenyltetracarboxylic dianhydride (BPDA) is mixed with diamine and dianhydride in a total molar ratio of 1 to 1 to prepare a polyamic acid, which is imidized to be linearly irregular. Characterized in that consisting of molecular weight 5,000 to 1,000,000 arranged so as to.

In addition, the thickness of the insulating layer is also characterized by 1.0㎛ to 10㎛.

In addition, the metal layer is characterized in that it comprises an organometallic compound prepared by reacting with a metal compound and one or two or more mixtures selected from ammonium carbamate-based compounds, ammonium carbonate-based compounds or ammonium bicarbonate-based compounds There is this.

In addition, the solvent for the mixture for the preparation of the polyimide film is water, methanol, ethanol, isopropanol, 1-methoxypropanol, butanol, ethylhexyl alcohol, terpineol, ethylene glycol, ethyl acetate, butyl acetate, methoxy Propyl acetate, methyl cellosolve, butyl cellosolve, diethyl ether, methyl ethyl ketone, acetone, dimethylformamide, 1-methyl-2-pyrrolidone, dimethyl sulfoxide, hexane, heptane, toluene, xylene, It is characterized by being methylene chloride, acetonitrile or a mixed solvent thereof.

In addition, the thickness of the metal layer is also characterized in that 0.05㎛ to 3㎛.

In addition, the conductive adhesive layer is formed of a conductive adhesive layer composition comprising 1.5 to 2.5 times by weight of the mixed conductive filler consisting of a conductive filler in the form of particles and a conductive filler in the form of fibers per 100 parts by weight of the binder resin composition, the conductive adhesive The binder resin composition for forming the layer composition and the insulating layer is composed of 50 to 150 parts by weight of the thermosetting resin, 5 to 20 parts by weight of the curing agent, and 10 to 30 parts by weight of the phosphorus flame retardant per 100 parts by weight of the thermoplastic resin, the thermoplastic resin (NBR ) Is also characterized by a weight average molecular weight of 3,000 ~ 300,0000.

In this case, the thermosetting resin of the binder resin composition is characterized by consisting of at least one thermosetting material selected from the group consisting of an epoxy resin, an unsaturated polyester resin, an acrylic resin and a phenol resin resin.

Moreover, the thermosetting resin of the said binder resin composition has the characteristic also that it is a polyfunctional epoxy which consists of resin whose weight average molecular weights are 300-3,000.

And, the curing agent is characterized in that consisting of at least one material selected from aromatic amine compound curing agent or imidazole curing agent.

In addition, the phosphorus-based flame retardant is characterized in that the melting point is 150 ~ 300 ℃.

In addition, the conductive filler in the form of particles is composed of at least one powder selected from the group consisting of gold powder, silver powder, silver coated copper powder, silver coated nickel powder and silver coated iron powder, the particle size is 1.0 ~ 20 The characteristic is also that it is a micrometer.

On the other hand, in the electromagnetic wave shielding film manufacturing method according to an embodiment of the present invention, after applying the composition solution for the insulating layer to the release film and dried, attaching a carrier film on one surface, removing the release film to form an insulating layer to form an insulating layer And a metal layer forming step of forming a metal layer by coating and drying a metal ink on the upper surface of the insulating layer, and adding a binder resin composition and a mixed conductive filler to a solvent and stirring the solution of the composition for a conductive adhesive layer prepared on a release film. A conductive adhesive layer forming step of coating and drying to form a conductive adhesive layer, and a laminating step of laminating the conductive adhesive layer and the metal layer to face each other.

In this case, the release film is a PET film subjected to silicone release treatment, the carrier film may be an acrylic pressure-sensitive adhesive or a matte PET release protective film.

In addition, the electromagnetic wave shielding film manufacturing method according to another embodiment of the present invention, after coating the composition solution for the insulating layer on the release film and dried, the carrier film is attached to one surface, and the release film is removed to form an insulating coating layer A layer forming step, a metal layer forming step of forming a metal layer by coating and drying a metal ink on the upper surface of the insulating layer, and adding a binder resin composition and a mixed conductive filler to a solvent and stirring the solution of the composition for a conductive adhesive layer prepared It is characterized in that it comprises a; conductive adhesive layer forming step (S130) is applied to the upper portion of the metal layer and dried to form a conductive adhesive layer.

In this case, a release film may be attached to the conductive adhesive layer formed in the conductive adhesive layer forming step.

In addition, the solvent for the composition solution for the conductive adhesive layer and the composition solution for the insulating layer of the electromagnetic wave shielding film manufacturing method according to the embodiment of the present invention described above is characterized in that it is selected to be compatible with the binder resin composition, mixed conductive filler. have.

At this time, the content of the composition for the conductive adhesive layer or the composition for the insulating layer solid content in the composition solution for the conductive adhesive layer or the composition for the insulating layer is characterized in that the range of about 20 to 60% by weight.

In addition, the drying temperature is characterized in that selected in the range of about 80 ~ 150 ℃.

On the other hand, a printed circuit board with an electromagnetic wave shielding film according to the present invention, an insulating layer having a carrier film on one surface, a metal layer formed by coating and drying a metal ink on the upper surface of the insulating layer, and the top of the metal layer Electromagnetic shielding film comprising a conductive adhesive layer (Conductive Adhesive layer) formed by coating and drying a conductive adhesive composition on the surface of the printed circuit board is formed by attaching by a hot press process.

In addition, the method of manufacturing a printed circuit board includes an insulating layer forming step of forming an insulating layer by applying a composition solution for an insulating layer to a release film, drying and attaching a carrier film to one surface, and removing the release film, and the insulating layer. Coating the metal ink on the upper surface of the metal layer forming step of forming a metal layer, and the conductive resin layer composition solution prepared by adding and stirring a binder resin composition and a mixed conductive filler in a solvent on a release protective film and dried to conduct conductive A conductive adhesive layer forming step of forming an adhesive layer, a laminating step of laminating the conductive adhesive layer and the metal layer so as to face each other, and attaching the conductive adhesive layer to a press formed such that the conductive adhesive layer is adhered to a surface on which a circuit pattern of a printed circuit board is formed. Hot pressing process for performing a hot press after; The.

In addition, according to another aspect of the present invention, a method for manufacturing a printed circuit board with an electromagnetic wave shielding film includes applying a composition solution for an insulating layer to a release film, drying, and attaching a carrier film to one surface thereof, and removing the release film. Forming an insulating layer, and forming a metal layer by coating and drying a metal ink on the upper surface of the insulating layer; and adding a binder resin composition and a mixed conductive filler to a solvent, and preparing a conductive adhesive layer by stirring. A conductive adhesive layer forming step of applying a composition solution on top of the metal layer and drying to form a conductive adhesive layer, and attaching the conductive adhesive layer to a surface on which a circuit pattern of a printed circuit board is formed, and then attaching a hot press to the press It is characterized by comprising a hot press process to perform.

Electromagnetic wave shielding film according to the present invention is excellent in adhesion, heat resistance, electrical conductivity, bending resistance, wear resistance, and flame retardancy, printed circuit board, in particular, a flexible printed circuit board (FPCB, which requires high flexibility, high adhesion, high heat resistance, etc.) It can be reliably applied to one or both sides of the Flexible Printed Circuit Board.

Accordingly, the present invention provides an effect of effectively attenuating various electromagnetic waves generated in a substrate circuit.

1 is a cross-sectional view of an electromagnetic wave shielding film according to an embodiment of the present invention,
2 is a view showing a wear resistance test apparatus,
3 is a view showing a specimen for measuring electrical conductivity,
4 is a view showing the flexibility test apparatus,
5 is a flow chart showing a process of a method for manufacturing an electromagnetic wave shielding film and a method for manufacturing a printed circuit board with an electromagnetic wave shielding film according to an embodiment of the present invention;
6 is a flowchart illustrating a process of manufacturing a method for manufacturing an electromagnetic wave shielding film and a method for manufacturing a printed circuit board with an electromagnetic wave shielding film according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings showing an embodiment of the present invention will be described in more detail the present invention.

Before describing the present invention, the following specific structural or functional descriptions are merely illustrative for the purpose of describing an embodiment according to the concept of the present invention, and embodiments according to the concept of the present invention may be embodied in various forms, And should not be construed as limited to the embodiments described herein.

In addition, since the embodiments according to the concept of the present invention can make various changes and have various forms, specific embodiments are illustrated in the drawings and described in detail herein. However, it should be understood that the embodiments according to the concept of the present invention are not intended to limit the present invention to specific modes of operation, but include all modifications, equivalents and alternatives falling within the spirit and scope of the present invention.

As shown in FIG. 1, the electromagnetic wave shielding film 10 according to the present invention has a multilayer structure including a conductive adhesive layer 4 and an insulating layer 2 laminated on one surface thereof.

In addition, the electromagnetic wave shielding film 10 may include an insulating layer 2 formed on one surface of the carrier film 1, a metal layer 3 formed by coating and drying the metal ink on the insulating layer 2, and laminated; The conductive adhesive layer 4 formed by lamination or lamination on the upper part of the metal layer 3, and the release film 5 which protects the exposed surface of the conductive adhesive layer 4 are comprised.

In this configuration, the release film 5 is removed before performing the hot press process as protecting the conductive adhesive layer 4 before the hot press process.

The electromagnetic wave shielding film 10 having the above configuration is a hot press method in which a conductive adhesive layer 4 is attached to a surface on which a circuit pattern of a printed circuit board mounted on a press is formed after removing the release film 5. By attaching to the printed circuit board (not shown) to which the electromagnetic shielding film is attached.

As described above, when the electromagnetic wave shielding film 10 is attached to a printed circuit board (not shown), the conductive adhesive layer 4 absorbs electromagnetic waves generated in a circuit pattern on the printed circuit board (not shown), and then a metal layer. By transmitting to (3), a function of eliminating the electromagnetic waves causing interference between circuit patterns is performed.

Hereinafter, the electromagnetic wave shielding film 10 according to the embodiment of the present invention will be described by dividing the carrier film 1, the insulating layer 2, the metal layer 3, and the conductive adhesive layer 4.

1. Carrier Film

The carrier film 1 serves to prevent contamination by foreign matter from the external environment and to protect the surface in the hot pressing process until the electromagnetic wave shielding film 10 is used by the end-user.

The carrier film 1 has a silicone, fluorine, long chain alkyl acrylate or the like formed on the surface of the base film formed of a material such as polyethylene, polypropylene, or polyethylene terephthalate in order to more easily peel off the electromagnetic wave shielding film 10. Use a release agent treated with.

2. Insulation layer

The electromagnetic wave shielding film 10 according to the present invention includes an insulating layer 2 formed by applying a composition solution for an insulating layer to a release film, drying, attaching a carrier film 1 to one surface, and removing the release film. .

At this time, the insulating layer 2 is made of a polyimide resin.

The electromagnetic wave shielding film 10 according to the present invention may be any type as long as it can have component reliability in terms of basic physical properties, that is, adhesive force, heat resistance, chemical resistance, flexibility, flame retardancy, and the like, to be used as an adhesive material for a circuit board.

In the present invention, the polyimide resin is prepared from a polyamic acid precursor obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in a polar aprotic solvent.

Preferably the dianhydride is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-Biphenyltetracarboxylicdianhydride (BPDA), pyromellitic hydride (Pyromellitic) dianhydride: PMDA) and benzophenonetetracarboxylicdianhydride (BTDA). Preferably the diamine is p-phenylenediamine (pPDA), oxydianiline (ODA), N, N'-diphenylmethylenediamine (MDA) and diaminobenzo Phenone (diaminobenzophenone (DABP)). More preferably, the dianhydride comprises BPDA and PMDA and the diamine comprises PPDA and ODA.

As the organic solvent used to prepare the polyamic acid copolymer, it is preferable to use a polar solvent such as ether and ketone which are compatible with the polyamic acid produced after polymerization.

Specific examples include 1-methyl-2-pyrrolidone (hereinafter referred to as NMP), N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). One or more selected from the group can be used alone or in combination.

When the polymerized polyamic acid is cured and imidized, a polyimide copolymer, which is the insulating layer resin of the present invention, can be prepared. Thus, the polyamic acid precursor synthesized by dianhydride and diamine is polyimide by dehydration imidization. Can be mad.

Dehydration imidization reactions are classified into chemical imidization methods and thermal imidization.

Any dehydration method, including these two combinations, may be applied to the preparation of the polyimide.

The chemical imidization method includes a step of chemically dehydrating the acid by reacting the polyamic acid obtained in the above method with a dehydrating agent capable of hydrolyzing the acid.

Examples of dehydrating agents usable in this method include dicarboxylic acid anhydrides such as acetic anhydride and trifluoroacetic anhydride; Typically, derivatives of polyphosphoric acid, phosphorus pentoxide and the like: acid chlorides such as methanesulfonic acid chloride, phosphorus pentachloride and thionyl chloride are exemplified.

Two or more of these dehydrating agents may be used alone or in combination.

The amount of the dehydrating agent to be used is in the range of 2 to 10 moles, preferably 2 to 4 moles, per 1 mole of the total amount of the diamines used.

The chemical imidization reaction temperature is in the range of 70 ° C, most preferably room temperature, near room temperature.

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An additional solvent may be added to the reaction system in order to remove water formed through dehydration.

Benzene, toluene, o-, m-, p-xylene, o-, m-, p-chlorobenzene, o-, m-, p-chloro toluene etc. are mentioned as this solvent. These solvents may be used alone or in combination. The amount to be used is not particularly limited.

The reaction temperature, reaction time, and reaction pressure in thermal imidation are not particularly limited, and known conditions may be applied.

More specifically, the reaction temperature is 80 ° C to 400 ° C, preferably 100 ° C to 300 ° C, most preferably 150 ° C to 200 ° C. The reaction time depends on the type of solvent used and other reaction conditions, but is preferably in the range of 2 to 10 hours. The reaction pressure is sufficient at normal pressure.

3. Metal layer

The metal layer 3 is a thin film layer, and is formed by coating or drying a conductive metal ink composition such as silver nano ink on the upper surface of the insulating layer.

In other words, the thin metal layer 3 is formed by coating or printing the metal ink composition on the insulating layer 2.

At this time, the type of the metal ink is not particularly limited, and in particular, using a metal ink containing an organometallic complex compound having a special structure disclosed in Patent Application No. 2005-0034371, the uniform thickness and excellent conductivity of the metal thin film, It is also preferred because it has a low firing temperature and there is no residue other than the conductive material after the suit.

The metal ink may be prepared by reacting the metal ink with one or two or more mixtures selected from a metal compound, an ammonium carbamate compound, an ammonium carbonate compound, or an ammonium bicarbonate compound. [Ammonium carbamate compound, ammonium carbonate -Based compound or ammonium bicarbonate-based compound] to prepare a complex, the same production method for producing a metal ink including the same can be used.

Moreover, the conductor which forms the said metal layer 3 does not need to restrict | limit in particular, either. That is, any known one may be used as long as it meets the object of the invention.

Examples of the conductors include Ag, Au, Cu, Zn, Ni, Co, Pd, Pt, Ti, V, Mn, Fe, Cr, Zr, Nb, Mo, W, Ru, Cd, Ta, Re, Selected from a group of transition metals such as Os, Ir, or a group of metals such as Al, Ga, Ge, In, Sn, Sb, Pb, Bi, or actinides such as Lanthanides such as Sm, Eu, Ac, Th At least one metal selected from the (Aactinides) -based metal group, or alloys or alloy oxides thereof is included.

Preferably, it is Ag, Au, Cu, Zn, Most preferably, it is Ag which is excellent in electromagnetic wave shielding rate.

The solvent contained in the metal ink composition may be selected from water, alcohols, glycols, acetates, ethers, ketones, aliphatic hydrocarbons, aromatic hydrocarbons or halogenated hydrocarbon-based solvents, specifically, water, methanol, ethanol, isopropanol, 1 Methoxypropanol, butanol, ethylhexyl alcohol, terpineol, ethylene glycol, glycerin, ethyl acetate, butyl acetate, methoxypropyl acetate, carbitol acetate, ethyl carbitol acetate, methyl cellosolve, butyl cellosolve, Diethyl ether, tetrahydrofuran, dioxane, methyl ethyl ketone, acetone, dimethylformamide, 1-methyl-2-pyrrolidone, dimethyl sulfoxide, hexane, heptane, dodecane, paraffin oil, mineral spirit, benzene, One selected from toluene, xylene, chloroform, methylene chloride, carbon tetrachloride and acetonitrile or More than that can be used.

In addition, the printing method of the metal ink composition is spin coating, roll coating, spray coating, dip coating, flow coating, comma, respectively, depending on the properties of the ink and the properties of the resin layer. Coating, key coating, die coating, doctor blade, dispensing, inkjet, offset, screen pad, gravure, flexography, etc. If so, it is not particularly limited thereto.

In addition, if necessary, the printing method may be applied two or more times to form a pattern.

For example, a 0.1 um particle size metal ink composition is formed using a micro gravure coating machine to form a 0.3 um thick conductive pattern, and a 0.2 um particle size metal ink composition is formed using a silk screen to a thickness of 1 um or less. Patterns can be formed.

In addition, the post-treatment step may be heat treated under a normal inert atmosphere, but may be processed in air, nitrogen, carbon monoxide, or even a mixed gas of hydrogen and air or another inert gas, if necessary.

The heat treatment is usually carried out at a temperature of 80 to 400 ° C, preferably 90 to 300 ° C, more preferably 100 to 250 ° C.

In addition, it is also preferable to conduct the heat treatment at two or more stages at a low temperature and a high temperature within the above range for the uniformity of the thin film.

The thickness of the metal layer after the heat treatment is preferably between 0.1 ~ 2.0㎛ and also, the conductivity of the metal layer is a 1mΩ / cm ² ~ 1kΩcm ^2, preferably between ^{10mΩ / cm 2 ~ 5Ω / cm} 2 is preferred.

If the conductivity exceeds 5Ω / cm ² , the electromagnetic shielding property is lowered, and if the conductivity is 10 mΩ / cm ² or less, the shielding performance is improved, but manufacturing cost increases.

4. Conductive adhesive layer

The conductive adhesive layer 4 is formed of the composition for the conductive adhesive layer 4 containing the binder resin composition and the mixed conductive filler.

(1) binder resin composition

The binder resin composition includes a thermoplastic resin, a thermosetting resin, a curing agent and a phosphorus flame retardant. In addition, the binder resin composition may preferably further include a curing accelerator. In the conventional electromagnetic wave shielding film 10 manufacturing, the resin component of the binder resin composition uses an adhesive component capable of forming a film of a thin film using a solution coating process. In the present invention, a thermoplastic resin is used as the resin component of the binder resin composition. And thermosetting resins are used in combination, which is advantageous in terms of a circuit board manufacturing process manufactured through a high temperature hot press process, and more advantageous in terms of overall reliability of the circuit board after heat curing.

First, in order to improve the adhesion and coating property of the adhesive film, the adhesive composition contains a thermoplastic component. Such thermoplastic components are not particularly limited, and conventionally known thermoplastic components can be used. For example, Copolymer containing a vinyl monomer and acrylonitrile, styrene, etc. as a main component with acrylic rubber and acrylic acid alkyl ester (also including methacrylic acid ester); Polyisoprene rubber; Polybutadiene rubber; 1,2-polybutadiene rubber; Styrene-butadiene rubber; Acrylonitrile butadiene rubber (hereinafter also referred to as 'NBR'); Ethylene butadiene rubber; Carboxylated nitrile rubber etc. are mentioned preferably, More preferably, it is an acrylic rubber, NBR, ethylene butadiene rubber, or polybutadiene rubber, Especially preferably, it is NBR. The polybutadiene rubber or 1,2-polybutadiene rubber may be substituted with a carboxyl group or a hydroxyl group. The styrene butadiene rubber may be substituted with a hydroxyl group.

The NBR may be substituted with a carboxyl group, a hydroxyl group, or an acryloyl group. Such a thermoplastic component preferably has a functional group that reacts with the thermosetting component.

When the thermoplastic component and the thermosetting component react, there is an advantage in that the heat resistance is increased. Although it depends also on the kind of thermosetting component, a carboxyl group, an epoxy group, or a hydroxyl group etc. are mentioned suitably as said functional group, A carboxyl group is more preferable from a viewpoint of reactivity, universality, etc.

The NBR containing the carboxyl group has a weight average molecular weight of 2,000 to 300,000, preferably 3,000 to 200,000, and has an acrylonitrile content of 10 to 60 parts by weight, preferably 15 to 30 parts by weight, and a carboxyl group content. It shall be 1-20 weight part. At this time, when the weight average molecular weight of NBR is lower than 3,000, the thermal stability is poor, and when it is higher than 200,000, the solubility in the solvent is deteriorated. In addition, when the acrylonitrile content is lower than 15 parts by weight, the solvent solubility is lowered, and when higher than 30 parts by weight, the electrical insulation is poor. And when the content rate of the carboxyl group is 1 to 20 parts by weight, the adhesion between NBR and other resins, and the adhesive substrate is easy, so that the adhesive force increases.

Next, the reflow solder heat resistance and workability can be improved by including the thermosetting component in the thermosetting adhesive composition according to the present invention. In the related art, increasing the ratio of the thermoplastic resin to increase the adhesive strength reduces the thermosetting portion, thereby sacrificing heat resistance and workability, and increasing the ratio of the thermosetting resin to increase the heat resistance and workability has a problem in that the adhesive force is sacrificed. As the thermosetting resin used in the present invention, epoxy resins, phenol resins, vegetable oil-modified phenol resins, xylene resins, guanamine resins, diallyl phthalate resins, vinyl ester resins, unsaturated polyester resins, polyimide resins, and polyurethane resins are preferable. Preferably, it is an epoxy resin, a phenol resin, or a vegetable oil modified phenol resin, More preferably, it is an epoxy resin excellent in reactivity and heat resistance. Examples of such epoxy resins include bisphenol-type epoxy resins, bisphenol F-type resins, and bisphenol-type epoxy resins such as bisphenol S-type resins, phenol novolak-type epoxy resins, cresol novolak-type epoxy resins, and novolak-type epoxy resins such as bisphenol-A novolak-type epoxy resins. Resin, alicyclic epoxy resin, aliphatic chain epoxy resin, diglycidyl ether of biphenol, diglycidyl ether of naphthalene diol, diglycidyl ether of phenol, diglycidyl ether of alcohol And at least one selected from the group consisting of these alkyl substituents, halides, and hydrogen additives. Among these, bisphenol-A epoxy resin or novolak-type epoxy resin is particularly preferable.

The epoxy resin of the thermosetting adhesive composition according to the present invention may be added to 50 to 300 parts by weight based on 100 parts by weight of the thermoplastic resin (NBR) and the epoxy equivalent (g / eq) is preferably 180 to 1000. Preferably, the epoxy resin is characterized in that 50 to 100 parts by weight with respect to 100 parts by weight of NBR, which is less elasticity of the adhesive film in the semi-cured state when added more than the epoxy resin compared to the NBR and when the reinforcement and lamination This is because the airtightness is insufficient, the adhesive film is easily expanded due to thermal stimulation, and reinforcement and lifting may occur.

Moreover, the thermosetting adhesive composition which concerns on this invention can improve heat resistance by containing a hardening | curing agent, and can especially improve reflow solder heat resistance. As such a hardening | curing agent, a polyamine hardening | curing agent, an acid anhydride type hardening | curing agent, a boron trifluoride complex salt, a phenol resin etc. are mentioned, for example.

As said polyamine hardening | curing agent, For example, aliphatic amine hardening | curing agents, such as diethylene triamine, tetraethylene tetratamine, and tetraethylene pentamine; Alicyclic amine curing agents such as isophorone diamine; Aromatic amine curing agents such as diaminodiphenylmethane and phenylenediamine; Dicyandiamide, and the like. Phthalic anhydride, a pyromellitic anhydride, trimellitic anhydride etc. are mentioned as said acid anhydride type hardening | curing agent, for example. These hardeners may be used independently and may use two or more types together as needed.

It is preferable that 1-50 weight part of said hardening | curing agents of the thermosetting adhesive composition concerning this invention are contained with respect to 100 weight part of said thermoplastic resins, More preferably, it is 5-20 weight part.

At this time, if the content of the curing agent is 5 parts by weight or less, the reflow solder heat resistance of the adhesive film made of the adhesive composition of the present invention is lowered, if the concentration is 20 parts by weight or more, the workability of the adhesive composition is lowered, or of the present invention Outflow at the time of pressing of the adhesive film which consists of adhesive compositions increases.

The conductive adhesive layer 4 having the above composition has a viscosity of 100 to 2000 cps, preferably 400 to 1500 cps, and is applied on the release film 5 so as to have a thickness after drying of 8 to 20 μm and 2 to 50 to 200 ° C. After drying for 10 minutes, a thermosetting adhesive film is obtained through a process of coating on ultrathin metal, a release film and a lamination process. Alternatively, it may be obtained by laminating the release film 5 after coating the metal ultrathin layer directly.

On the other hand, the coating method is not particularly limited, and may be a coating method using a comma coater, reverse roll coater and the like.

In addition, the thickness, shape, etc. of the adhesive bond layer of the adhesive film which apply | coated the thermosetting adhesive composition which concerns on this invention are not specifically limited, It can determine suitably according to a use site and a use purpose.

(2) mixed conductive filler

The mixed conductive filler used in the present invention consists of a conductive filler in the form of particles and a conductive filler in the form of fibers.

Electromagnetic wave shielding film 10 according to the present invention, in addition to the realization of excellent electrical conductivity, even under repeated bending loads must be simultaneously implemented a high bendability that should not be cracked in the electromagnetic shielding film 10, to improve the electrical conductivity In order to use the conductive filler in the form of a large amount of particles, the brittleness of the electromagnetic wave shielding film 10 increases, resulting in a problem of deterioration in bending characteristics.

Therefore, in order to satisfy both the electrically conductive properties and the bendability characteristics of the electromagnetic wave shielding film 10, it is preferable to mix the conductive fillers in a certain amount to improve the electrical contact between the conductive fillers in the form of particles and to improve the bendability of the electroconductive adhesive film. Do.

In the conductive layer composition according to the present invention, the content of the mixed conductive filler is preferably 25 to 80 parts by weight per 100 parts by weight of the binder resin composition, and when less than 25 parts by weight, the electrical conductivity of the electromagnetic wave shielding film 10 is greatly reduced. If it exceeds 80 parts by weight, the brittleness of the electromagnetic wave shielding film 10 is increased and the flexibility is greatly reduced.

The conductive filler in the form of particles constituting the mixed conductive filler is composed of at least one powder selected from the group consisting of gold, silver, copper nickel and iron powder having excellent electrical conductivity.

Among them, the specific gravity is low in order to maintain the sedimentation rate relatively slow when mixing with the binder resin composition, the oxidation resistance is excellent, and the electrical contact forming ability between the filler particles is excellent, and the price increase factor according to the filler addition amount is relatively low. Powder is preferred.

The conductive filler in the form of particles may have specific shapes such as spherical shape, plate shape, and amorphous shape, and from the viewpoint of electrical contact formation, it is preferable to use a mixture of spherical shape, plate shape, and branch shape as appropriate.

In addition, the conductive filler in the form of particles is made of one or more powders selected from the group consisting of gold powder, silver powder, silver coated copper powder, silver coated nickel powder and silver coated iron powder, the particle size is 1.0 ~ 20㎛ It is preferable.

In general, the thickness of the conductive adhesive layer 5 is maintained at 15 μm or less from the standpoint of implementing flexural characteristics. When the particle size of the conductive filler in the form of particles is less than 0.1 μm, the probability of forming an electrical contact is low, which is satisfactory for the dose. When the conductivity is not obtained and exceeds 15 µm, it may be difficult to obtain the conductive adhesive layer 4 having a uniform physical property because the added particle size is too large relative to the thickness of the conductive adhesive layer 4.

To the adhesive composition of the present invention, any other components of those used in the adhesive composition, that is, tackifiers, stabilizers, antioxidants, fillers, reinforcing agents, pigments, antifoaming agents, and the like may be additionally added as necessary.

5. Release Film

The release film 5 is attached to the conductive adhesive layer 4 and serves to protect the conductive adhesive layer 4. The release film 5 is removed to attach the electromagnetic wave shielding film 10 to the printed circuit board by a hot press process. do.

6. Manufacturing method of electromagnetic wave shielding film

5 is a flowchart illustrating a process of a method of manufacturing an electromagnetic wave shielding film and a method of manufacturing a printed circuit board with an electromagnetic wave shielding film according to an embodiment of the present invention.

As shown in FIG. 5, the electromagnetic wave shielding film 10 is formed by applying a composition solution for an insulating layer to a release film, drying, attaching a carrier film to one surface, and removing the release film to form an insulating layer 2. (S10), a metal layer forming step (S20) of forming a metal layer 3 by coating and drying a metal ink on the upper surface of the insulating layer 2, and adding a binder resin composition and a mixed conductive filler to a solvent and stirring The conductive adhesive layer forming step (S30) of applying the prepared composition solution for the conductive adhesive layer 4 to the release film and drying to form the conductive adhesive layer (4), the conductive adhesive layer 4 and the metal layer (3) ) Is laminated so as to face each other (S40).

In the manufacturing method of the electromagnetic wave shielding film 10 of FIG. 5 described above, the type of the base film such as the carrier film 1 or the release film is not particularly limited. Preferably, in the case of the release film, a PET film subjected to silicone release treatment is used. The carrier film 1 may be acryl-based pressure-sensitive adhesive or matte PET release protective film.

The solvent for forming the conductive adhesive layer 4 is not particularly limited as long as it is compatible with the binder resin composition and the mixed conductive filler, and specific examples include mixing toluene / methylethyl ketone in a specific weight ratio. There is a mixed solvent.

In the composition solution for the conductive adhesive layer 4 or the composition solution for the insulating layer 2, the composition for the conductive adhesive layer 4 or the composition for the insulating layer 2, ie, the solid content, is in the range of about 20 to 60% by weight. It is preferable.

In addition, the drying temperature is appropriately selected depending on the type of the solvent used, and has a range of about 80 ~ 150 ℃.

In addition, the lamination is usually made by a hot roll press, the temperature of the hot roll has a range of about 100 ~ 120 ℃.

6 is a flowchart illustrating a process of manufacturing a method for manufacturing an electromagnetic wave shielding film and a method for manufacturing a printed circuit board with an electromagnetic wave shielding film according to another embodiment of the present invention.

According to FIG. 6, after applying the composition solution for the insulating layer to the release film and drying, the carrier film 1 is attached to one surface, and the release film is removed to form the insulation layer 2 by forming the insulation layer 2 (S110). And a metal layer forming step (S120) of forming a metal layer 3 by coating and drying a metal ink on the upper surface of the insulating layer 2, and adding a binder resin composition and a mixed conductive filler to a solvent and stirring The composition solution for the conductive adhesive layer 4 may be applied to the upper portion of the metal layer 3 and dried to form a conductive adhesive layer forming step (S130) to form the conductive adhesive layer 4.

In this case, even in the manufacturing method of Figure 6, if the solvent is compatible with the binder resin composition, mixed conductive fillers, the type is not particularly limited, specific examples are mixed solvents in which toluene / methyl ethyl ketone are mixed in a specific weight ratio, respectively There is.

Similarly, in the composition solution for the conductive adhesive layer 4 or the composition solution for the insulating layer 2, the composition for the conductive adhesive layer 4 or the composition for the insulating layer 2, that is, the content of solid content is about 20 to 60% by weight. It is preferable that it is the range of.

In addition, the drying temperature is also appropriately selected depending on the type of solvent used, and has a range of about 80 ~ 150 ℃. In addition, the lamination is usually made by a hot roll press, the temperature of the hot roll has a range of about 100 ~ 120 ℃.

The electromagnetic wave shielding film 10 formed by such a manufacturing method has a multilayer structure including a conductive adhesive layer 4 and an insulating layer. The electromagnetic wave shielding film 10 has a total thickness of about 10 to 20 μm, and is insulated. The thickness of the layer is about 3 to 5 mu m, preferably 5 mu m or less, and the thickness of the conductive adhesive layer 4 is about 5 to 20 mu m, preferably 8 to 16 mu m.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only intended to more clearly describe the present invention, and do not limit the protection scope of the present invention.

(Production of silver coated polyimide insulation layer)

3.39 g (31.4 mmol) of p-phenylenediamine (pPDA) and 7.85 g (39.3 mmol) of oxydianiline (ODA), 0.15 g (0.01) in 168 ml of N-methylpyrrolidone (NMP) solution 148 g of dianhydrous phthalic anhydride (PMDA) and cresol were added and stirred at 35 ° C. until a homogeneous diamine solution was formed at 60 rpm.

Then, 20.76 g (70.6 mmol) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to the diamine solution, and the mixture was stirred and stirred for 3 hours. The reaction was carried out to form a 18.6% polyamic acid solution as a weight solid.

Since dianhydrides react with polar aprotic solvents, pPDA and ODA solids were first added to the solvent, and then BPDA was gradually added to the diamine solution.

In addition, the reaction system was heated from room temperature to 200 ° C. over about 2 hours, and then further reacted for 4 hours to prepare a polyimide solution by a chemical imidization method.

In the present invention, important properties of the resulting polyimide resin depend on the molar ratio of pPDA to ODA. For example, changing the molar ratio of pPDA to ODA will result in different values of the coefficient of thermal expansion and the flexibility of the polyimide resin.

In the experimental example, the molar ratio of dianhydride to diamine of the reactant of the polyamic acid solution was 1: 1, and the molar ratio of p-phenylenediamine (pPDA) to oxydianiline (ODA) of diamine was 0.8: 1.0. It was.

3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride (BPDA) and phthalic anhydride (PMDA) were used for this polyamic-acid solution as a multiple dianhydride component.

The obtained polyimide resin was dried on a silicone release coated PET film (36 μm, SKC) release treated surface using a comma coater and dried to a thickness of 5 μm, and then another PET carrier coated with an acrylic release agent on one surface thereof. It laminated on the acrylic mold release surface of the film (50 micrometers, Maxfill) at 80 degreeC.

After preparing PET film coated with acrylic release agent for metal lamination film manufacturing, coating conductive metal ink at 150 ℃, 10M / min rate on resin silver nano ink composition (TEC-IJ-020, Inktech) using gravure coater 0.3um thick thin film of the metal laminate film was prepared.

After the coating was completed, the conductivity of the formed metal layer was confirmed to be 0.5Ω / cm ² .

Then, an appropriate amount of a mixed solvent of toluene / methylethyl ketone (weight ratio is 50:50) is added to the stirrer, and thermoplastic resin, thermosetting resin, curing agent, curing accelerator, flame retardant and conductive metal powder are sequentially added thereto, followed by stirring. A thermosetting conductive adhesive composition solution was obtained.

The obtained composition solution for the conductive adhesive layer 4 was applied to the silver layer surface of the silver-coated polyimide film obtained above with a bar coater and dried in a drying furnace at 120 ° C. for 5 minutes to remove the solvent, thereby thermosetting conductive adhesive layer ( 4) The electromagnetic wave shielding film 10 of the multilayer structure which has a thickness of 10 micrometers was manufactured.

Ο: applied x: not applied

PI film: synthetic polyimide film + ultrathin silver layer

PPS film: polyphenylene sulfide film + ultrathin silver layer

m-Epoxy: Modified Epoxy Film

NBR: acrylonitrile butadiene rubber, Zeon Chemical, Nipol-1072

4P: YDCN 500-4P, cresol novolac epoxy, Kukdo Chemical

F170: YDF-017, Bisphenol F epoxy, Kukdo Chemical

C3000: LC-3000, latent hardener, Shin-A T & C Co., Ltd.

2E4MZ: 2-ethyl4-methylimidazole, Air Products and Chemicals, Inc.

OP930: Exolit OP-935, phosphinate powder, Clariant Co.

Ag1110: CE-1110, silver coated copper powder, FUKUDA METAL FOIL & POWDER CO., LTD.

As shown in Table 1, Examples 1 to 5 prepared a PI-based electromagnetic wave shielding film according to the present invention, Comparative Example 1 used a commercial polyphenylene sulfide film instead of a synthetic polyimide film, Comparative Example 2 is a support film Instead of using a solution that removes the metal powder from the conductive adhesive composition was used to form a film after forming a film according to the synthetic polyimide insulating layer manufacturing method.

Table 1 shows the components and contents of the binder resin composition prepared by Examples 1 to 5 and Comparative Examples 1 to 2. In addition, Table 2 shows the characteristics of the electromagnetic wave shielding film prepared by Examples 1 to 5 and Comparative Examples 1 to 2.

(Evaluation of Properties of Electromagnetic Wave Shielding Film)

The abrasion resistance, the electrical conductivity, the bending property, the adhesive force, the heat resistance, and the flame resistance of the electromagnetic wave shielding film 10 prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated based on the following physical property evaluation methods.

① Wear resistance

After cut | disconnecting the electromagnetic wave shielding film 10 to 20 mm and length 50 mm, a conductive adhesive layer (Copper Clad Laminate; 35 micrometers of copper foil thickness, 25 micrometers of polyimide film thicknesses) is carried out on the copper foil surface. 4) was welded so as to come in contact with each other and cured at 160 ° C. for 1 hour to prepare a specimen for measuring wear resistance.

2 is a diagram illustrating the wear resistance test apparatus 100.

As shown in Figure 2, the base 101, the support 110, the weight 120 and the friction member 130 is composed of a cylindrical rubber having a hardness of 1H and a diameter of 5mm mounted on the lower portion of the weight 120 The SUS plate 140 of the wear resistance test apparatus 100 includes a SUS plate 140 reciprocated on the base 101 and a cam motor 150 reciprocating the SUS plate 140 by the cam loader 155. The electromagnetic wave shielding film 10 is attached to the insulation layer by using a double-sided adhesive tape, and then reciprocated 1500 times under a condition of a reciprocating distance of 40 mm with a friction member 130 acting on a load of 500 g. Then, the presence of scratches or wear on the surface of the insulating layer (2) was visually determined to determine the degree of wear as follows, and the results are shown in Table 2 using the following symbols.

○: no change in surface of insulating film (good)

△: scratch marks on some film surfaces

X: The insulating layer is worn and the lower conductive adhesive layer is exposed (defect).

② electrical conductivity

3 is a diagram illustrating a test piece 200 for measuring electrical conductivity.

As shown in FIG. 3, the CCL terminal 220 having a width of 5 mm and a length of 30 mm having a diameter of 1 mm of the hole 223 inscribed in the cover layer layer 210 is placed side by side so that the distance between the holes 223 is 50 mm. After arranging the stepped portion 230 between the terminals 220, the conductive adhesive layer 4 of the electromagnetic wave shielding film 10 having a width of 10 mm is welded and cured at 160 ° C. for 1 hour to measure electrical conductivity. For specimen 200 was prepared.

Then, the resistance between the CCL terminals 220 was measured using the tester 20.

At this time, the step portion 230 may be variously modified to 50, 100, 200, 400㎛, and the like.

③ bendability

4 is a diagram illustrating the flexibility test apparatus 300.

A test piece 300 for measuring flexibility was prepared by welding the cover layer side of the CCL terminal 220 having a circuit pattern having a width of 75 μm and a length of 80 mm to cover the conductive adhesive layer of the electromagnetic wave shielding film and curing at 160 ° C. for 1 hour. It was.

As shown in FIG. 4, after the specimen is mounted on the SUS plate 140 reciprocated from the upper portion of the base 101, the cam rod 155 and the cam are maintained with a bending radius of 1.0 mm. After driving the SUS plate 140 at a reciprocating distance of 20 mm and 60 reciprocating speeds per second using the motor 150, the electric resistance according to the number of round trips is measured using a tester 20 (in this case, a milliohm meter). And the number of round trips at the time exceeding 20% of the initial resistance value was evaluated by the bending performance of the electromagnetic wave shielding film 10 and the results are shown in Table 2 using the following symbols.

○: More than 300,000 times (good)

△: less than 100,000-300,000 times

×: less than 100,000 times (defective)

④ adhesion

The electromagnetic wave shielding film 10 is welded so that the conductive adhesive layer 4 is in contact with the copper foil surface of the single-sided CCL terminal 220 (copper foil 1 oz / PI film 1 mil) and cured at 160 ° C. for 1 hour to measure adhesion. Specimen was prepared. After cutting to 10 mm in width and 50 mm in length, the strength was measured while peeling the electromagnetic shielding film 10 at a 90 ° angle with a tensile strength tester to measure the adhesive force of the adhesive film.

⑤ heat resistance

In order to evaluate the soldering heat resistance of the electromagnetic wave shielding film 10, a specimen attached to the cross-section CCL was prepared in the same manner as the specimen for measuring the adhesive force, and then cut into 20 mm long and 20 mm long, and placed in a 280 ° C. solder bath. After floating for a second, the deformation and bubble generation on the surface of the adhesive film were evaluated based on the following criteria and are shown in Table 2.

○: No bubble formation or surface deformation (good)

△ no bubble generation but surface deformation observed

×: Both bubble formation and surface deformation are observed (defect)

⑥ Flame retardant

After preparing the specimen attached to 2mill Kapton PI (DuPont) in the same manner as the specimen for measuring the adhesive force, cut into 50mm horizontally, 200mm vertically and evaluated the flame retardancy according to the standard of UL 94 VTM-0 to use the following symbols Table 2 shows.

If flame retardant meets VTM-0 specification: ○ (good)

If flame retardancy does not meet VTM-0 specification: × (defective)

Ο: Good x: Bad

NM: Not measurable

In addition, the printed circuit board with an electromagnetic shielding film according to an embodiment of the present invention, the carrier film (Release Protection Film), and the insulating layer (Substrate layer) provided with a polyimide film on one side of the carrier film; The electromagnetic wave shielding film comprising a conductive adhesive layer provided through a metal layer on a surface opposite to a surface of the carrier film, the surface of which is formed by a circuit of a printed circuit board by a hot press process. Attached and manufactured.

In the method of manufacturing a printed circuit board with an electromagnetic plate shielding film according to an embodiment of the present invention as shown in FIG. 5, after applying the composition solution for the insulating layer to a release film and drying, the carrier film is attached to one surface, and the release film An insulating layer forming step (S10) of forming an insulating layer (2) by removing the insulating layer, and a metal layer forming step (S20) of forming a metal layer (3) by coating and drying a metal ink on an upper surface of the insulating layer (2); The conductive adhesive layer forming step of applying the composition solution for the conductive adhesive layer 4 prepared by adding and stirring the binder resin composition and the mixed conductive filler to the solvent on a release film and drying to form the conductive adhesive layer 4 (S30). ), A lamination step (S40) of laminating the conductive adhesive layer 4 and the metal layer 3 so as to face each other, and a press machine such that the conductive adhesive layer 4 is adhered to a surface on which a circuit pattern of a printed circuit board is formed. After mounting can be achieved, including the hot press process (S50) to perform the hot press.

In addition, a method of manufacturing a printed circuit board with an electromagnetic plate shielding film according to another embodiment of the present invention as shown in FIG. 6, by coating and drying a metal ink on the upper surface of the insulating layer 2 to form a metal layer 3. The metal layer forming step (S120) to be formed, and the composition solution for the conductive adhesive layer 4 prepared by adding and stirring a binder resin composition and a mixed conductive filler in a solvent are applied to the upper portion of the metal layer 3 and dried to form a conductive adhesive. Hot press process of performing a hot press after mounting the conductive adhesive layer forming step (S130) to form a layer (4), and the conductive adhesive layer (4) is bonded to the surface on which the circuit pattern of the printed circuit board is formed It may be made, including (S140).

10: electromagnetic shielding film,
1: carrier film, 2: insulating layer, 3: metal layer
4: conductive adhesive layer, 5: release film
100: wear resistance test device
200: test piece for measuring the electrical conductivity,
220: CCL terminal, 223: hole, 230: stepped portion
300: flexibility test device

Claims (20)

delete delete delete delete delete delete delete delete delete delete delete delete An insulating layer forming step of applying the composition solution for the insulating layer to the release film and drying the adhesive film to one surface, and removing the release film to form an insulating layer; A metal layer forming step of forming a metal layer by coating and drying a metal ink on the upper surface of the insulating layer; A conductive adhesive layer forming step of adding a binder resin composition and a mixed conductive filler to a solvent and stirring the composition solution for the conductive adhesive layer prepared by stirring, onto a release film and drying to form a conductive adhesive layer; An insulating layer having a carrier film attached to one surface through a lamination step of laminating the conductive adhesive layer and the metal layer to face each other, a metal layer formed by coating and drying a metal ink on an upper surface of the insulating layer, and an upper portion of the metal layer In the electromagnetic wave shielding film manufacturing method to have a conductive adhesive layer (Conductive Adhesive layer) formed by coating and drying a conductive adhesive composition;
The insulating layer formed through the insulating layer forming step is made of a polyimide resin,
The polyimide resin is prepared by reacting a polyamic acid precursor synthesized by dianhydride and diamine with two or more dehydrating agents of acetic anhydride, trifluoroacetic anhydride, polyphosphoric acid, methanesulfonic acid chloride, and thionyl chloride. Electromagnetic wave shielding film manufacturing method characterized in that produced by. delete delete delete delete delete delete delete

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