KR20170085939A - Method for preparing emi shielding film and emishielding film prepared by the method - Google Patents

Abstract

The present invention relates to a method for producing an electromagnetic wave shielding film and a shielding film produced by the method. More particularly, the present invention relates to a method for producing an electromagnetic wave shielding film, And 40 to 55% by weight of a conductive powder; and a conductive layer forming step of forming a conductive layer on the first film and a conductive layer comprising a conductive layer containing 9 to 15% by weight of a binder, 1 to 5% by weight of a curing agent, % Of a filler and 40 to 55 wt% of a filler, and a lamination step of laminating the first film and the second film, wherein the binder is a polyester-modified At least one of urethane resin, synthetic epoxy resin, thermoplastic polyurethane (TPU) and polyurethane urea is selected.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electromagnetic wave shielding film,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electromagnetic wave shielding film and an electromagnetic wave shielding film produced by the method. More particularly, the present invention relates to an electromagnetic wave shielding film which can prevent physical deformation of a flexible printed circuit board (FPCB) A method for manufacturing a thin film electromagnetic wave shielding film, and an electromagnetic wave shielding film produced by the method.

In recent years, a flexible printed circuit board (FPCB) having a thin and free curvature has been spotlighted due to the tendency of electronic devices to be miniaturized, highly integrated, simplified, high-performance and multifunctional, and high density, thin film, And so on. The FPCB is required to have an electromagnetic wave shielding function in order to prevent electromagnetic interference (EMI) between adjacent circuits.

Generally, an electromagnetic wave shielding layer is provided in order to prevent electromagnetic wave interference or the like of the FPCB, or an electromagnetic wave shielding film is combined. The electromagnetic wave shielding film is typically manufactured by forming a metal layer for electromagnetic shielding on an insulating layer formed by wet-coating an epoxy resin on a polyethylene terephthalate film, and coating a conductive adhesive for bonding the printed circuit board thereon by a wet method . Here, the metal layer performs an electromagnetic wave shielding function. Generally, silver is used because silver has the highest electrical conductivity among metals, and thus has excellent electromagnetic shielding function.

However, the electromagnetic wave shielding film applied to the flexible circuit board (FPCB) is required to have flexibility and heat resistance. If the electromagnetic wave shielding film having a high coefficient of thermal expansion is applied to the FPCB, the physical form of the FPCB can be deformed, resulting in poor quality stability.

KR 10-1516969 B1 KR 10-1538703 B1

In order to solve the above problems, the present invention provides a method for manufacturing a thin film electromagnetic shielding film capable of preventing physical deformation of a flexible printed circuit board (FPCB) by improving shrinkage and heat resistance, and a shielding film manufactured by the method It has its purpose.

It is another object of the present invention to provide a method for manufacturing an electromagnetic wave shielding film in which a silylated epoxy having a low shrinkage ratio and improved heat resistance is applied to a conductive layer and an insulating layer, and a shielding film produced by the method.

In order to attain the above object, the present invention provides a method for producing an electromagnetic wave shielding film, comprising the steps of: providing a first film comprising 9 to 15 wt% of a binder, 1 to 5 wt% of a curing agent, 35 to 40 wt% of a solvent, A conductive layer comprising a conductive composition comprising a conductive composition comprising a binder and a filler in an amount of from 9 to 15% by weight of a binder, from 1 to 5% by weight of a curing agent, from 35 to 40% by weight of a solvent and from 40 to 55% And a lamination step of laminating the first film and the second film, wherein the binder formed on the conductive layer and the insulating layer is a polyester-modified urethane Resin, a synthetic epoxy resin, a thermoplastic polyurethane (TPU), and a polyurethane urea.

The synthetic epoxy resin is characterized in that an O-cresol novolac epoxy having a structure of the formula (S1) is silylated.

[Formula (S1)

The synthetic epoxy resin is characterized in that one or two of the four rings of the silylated O-cresol novolac epoxy are silylated.

The synthetic epoxy resin is characterized in that an intermediate product of the structure of the formula (S2) is formed after stirring the O-cresol novolak epoxy (Ortho-Cresol Novolac Epoxy).

≪ RTI ID = 0.0 &

The synthetic epoxy resin is characterized by being an O-cresol Novolac Epoxy of formula (S3) wherein 1 to 2 of four rings are silylated in the intermediate product.

[Formula (S3)

Wherein the conductive layer and the binder include a synthetic epoxy resin and a thermoplastic polyurethane (TPU), and when the synthetic epoxy resin is 1, a binder is formed at a ratio of 1: 0.11 to 0.17 .

The solvent is selected from the group consisting of methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl acetate, methyl pyrrolidone, acetone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone (MEK), toluene Dibasic Ester) or is an aqueous solution in which they are mixed with water.

The forming of the insulating layer may be performed by using a filler having a thickness larger than that of the insulating layer, and the lamination step may include laminating the conductive layer on the uneven surface of the insulating layer.

Further, the electromagnetic wave shielding film of the present invention is characterized in that the electromagnetic wave shielding film produced by the method of the present invention comprises the conductive layer formed on one surface of the first film and the insulating layer formed on one surface of the second film And a thickness of 130 to 190 占 퐉 adjacent to each other.

The electromagnetic wave shielding film is characterized in that the thickness of the conductive layer is 10 to 15 mu m.

The electromagnetic wave shielding film is characterized in that the thickness of the insulating layer is 10 to 15 mu m.

Wherein the insulating layer has a cross-section of 1 to 20 占 퐉.

The electromagnetic wave shielding film has a thermal expansion coefficient of 4 to 10 ppm / 占 폚.

As described above, the electromagnetic wave shielding film produced by the method of the present invention includes an epoxy synthesis process with a low shrinkage ratio and improved heat resistance, and the synthesized epoxy is applied to the conductive layer and the insulating layer, , Heat resistance and sheet resistance are improved.

In addition, the electromagnetic wave shielding film formed by the manufacturing method of the present invention has an advantage of being able to maintain quality stability because it prevents physical deformation of the flexible circuit board (FPCB).

1 is a flowchart illustrating a method of manufacturing a shielding film according to the present invention.
Fig. 2 is a graph showing the results of Example 1 of the shielding film produced by the manufacturing method of Fig. 1 and Comparative Example 1. Fig.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown.

Hereinafter, a method for manufacturing an electromagnetic wave shielding film of the present invention and a shielding film produced by the method will be described.

1 is a flowchart illustrating a method of manufacturing a shielding film according to the present invention.

The method for producing a shielding film according to the present invention includes a conductive layer forming step (S10) for forming a conductive layer on one surface of a first film, an insulating layer forming step (S20) for forming an insulating layer on one surface of the second film, And a lamination step (S30) of laminating the second film. The lamination step is characterized in that the insulating layer of the second film is positioned on the conductive layer of the first film.

In the conductive layer forming step (S10), a conductive layer is formed on one surface of the first film. The first film prevents contamination from the external environment and protects the conductive layer in the lamination step. The first film is characterized in that a material selected from polyethylene, polypropylene, and polyethylene terephthalate is treated with a release agent such as a silicone-based, fluorine-based, or long chain alkyl acrylate-based material.

The first film may have a thickness of 55 to 80 탆, and preferably 60 to 80 탆. If the thickness of the first film is as small as 55 mu m or less, it can be torn in the lamination step. If the thickness of the first film is 80 mu m or more, the flexibility is low and it is difficult to apply to the flexible circuit board (FPCB).

The conductive layer comprises a conductive composition comprising 9 to 15% by weight of a binder, 1 to 5% by weight of a curing agent, 35 to 40% by weight of a solvent, and 40 to 55% by weight of a conductive powder. The conductive layer is formed to a thickness of 10 to 15 탆.

The binder is characterized in that at least one of a polyester-modified urethane resin, a synthetic epoxy resin, a thermoplastic polyurethane (TPU) and a polyurethane-urea is selected. Preferably, two resins are included.

The synthetic epoxy resin is characterized by being a silylated epoxy having a low coefficient of thermal expansion (CTE), sheet resistance and heat resistance. The silylated epoxy is characterized in that an O-cresol novolac epoxy having a structure of the formula (1) is silylated.

In the general formula (1), n is an integer of 1 or more, preferably an integer of 1 to 1000. 20 g of the O-cresol novolak epoxy resin having the structure of the above formula 1 was put into a two-necked flask, and 38 ml of EtOH, 1.33 g of NaOH, 1.61 g of Et ₄ NBr, 51 ml of THF and 51 ml of CH ₃ CN were added, Stir time.

After stirring, 5 ml of a saturated solution of NH ₄ Cl is added, followed by stirring for 3 minutes. Then, the solvent is removed using a rotary evaporator. Then, the organic layer was separated with 400 ml of EA and 300 ml of H2O in each work-up, and the remaining organic layer was washed with MgSO ₄ to remove H ₂ O. After the MgSO ₄ filtration, the solvent is evaporated by an evaporator to obtain an intermediate of formula (2).

In the general formula (2), n is an integer of 1 or more, preferably an integer of 1 to 1000. 20 g of the intermediate product having the structure of the above formula (2), 7.8 ml of 3- (triethoxysilyl) propyl isocyanate, 5.5 g of DIPEA and 51 ml of CH ₃ CN are put into a two-necked flask and stirred at 65 ° C for 20 hours.

After the reaction the stirring was terminated, and then the input 300ml EA, and then NH ₄ Cl and then worked up with saturated aqueous solution, to remove H2O remaining in the organic layer with MgSO _4. The MgSO ₄ is filtered and the organic solvent is evaporated with an evaporator. After removing the organic solvent, hexane is added to the crude product and precipitated at -15 ° C. The supernatant of the precipitate is removed and hexane is poured into the precipitate to obtain the final product of formula (3).

In Formula 3, n is an integer of 1 or more, and preferably an integer of 1 to 1000. The silylated epoxy of Formula 3 has improved thermal expansion coefficient and heat resistance. In the present invention, one or two of the four rings are silylated.

The curing agent comprises 1 to 5% by weight. The curing agent is not particularly limited as long as it is a known one. Specific examples thereof include an amine compound, a phenol resin, an acid anhydride, an imidazole compound, a polyamine compound, a hydrazide compound and a dicyandiamide compound. The curing agent is preferably composed of at least one material selected from an aromatic amine compound curing agent and a phenol resin curing agent. The aromatic amine compound curing agent or the phenolic resin curing agent has an advantage of less change in adhesion property even when stored at room temperature for a long period of time. Examples of the aromatic amine compound curing agent include m-xylene diamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodearyl diphenylmethane, diaminodiphenyl ether, 1,3-bis (4 (4-aminophenoxy) phenyl] sulfone, 4,4'-bis (4-aminophenoxy) -Aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy) benzene, and the like, which may be used alone or in combination. Examples of the phenol resin curing agent include phenol novolac resins, cresol novolac resins, bisphenol A novolak resins, phenol aralkyl resins, poly-p-vinylphenol t-butylphenol novolak resins, and naphthol novolac resins. These may be used alone or in combination. If the content of the curing agent is less than 1% by weight, the effect of curing on the thermosetting resin is insufficient and the heat resistance is lowered. When the content of the curing agent is more than 5% by weight, the reactivity with the thermosetting resin becomes high, And long-term storage property.

The content of the solvent is 35 to 40% by weight. The solvent is selected from the group consisting of methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl acetate, methyl pyrrolidone, acetone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone (MEK), toluene Dibasic Ester), or they may be used in the form of an aqueous solution in which they are mixed with water. However, the same solvent may be used to dissolve the binder resin or to disperse the conductive powder, Other solvents may be used.

The conductive powder includes 40 to 55% by weight. The conductive powder is composed of any one selected from a metal powder having excellent electrical conductivity and a metal oxide powder having a metal coated on its surface. The conductive powder may be at least one selected from the group consisting of silver (Ag), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), and copper (Cu) ) Or silver (Ag) coated copper (Cu) powder may be used. Specific examples of the metal powder usable in the present invention may include ferrosilane SF-70A, SF-9ED, SF-7A, SF-7E, SF-9, SF- Silver coated copper powders include Ferrosa AgCu-200, AgCu-250, AgCu-300 and AgCu-400.

Preferably, the copper (Cu) powder coated with silver (Ag) has excellent electrical conductivity and greatly increases abrasion resistance. In the case of the silver (Ag) powder, a flake phase powder having an average particle size (D50) of 1 to 10 mu m is used. In the case of silver coated copper powder, a flake phase powder having an average particle size (D50) of 5 to 10 mu m is used. When the content of the metal powder is less than 40 wt%, the conductivity is poor, while when it exceeds 55 wt%, the manufacturing cost is excessively increased as compared with an increase in electromagnetic wave shielding effect.

The conductive composition may further include a dispersant, a surfactant, a wetting and dispersing agent, an antifoaming agent, an interfacial binder, a leveling agent, a rheology controller, etc., in addition to the materials described above. The surfactant is added so as to facilitate dispersion when the conductive powder is dispersed in a solvent, and a compound containing one or more of nonionic, cationic and anionic compounds may be used. The wetting and dispersing agent, antifoaming agent, interfacial bonding agent and leveling agent are added in order not only to facilitate dispersing of the conductive powder but also to improve the coating surface characteristics of the paint composition. Examples thereof include chlorine compounds, fluorine compounds, A compound, a glycol derivative, an epoxy, a carboxyl, an amine-terminated silane, or the like.

The conductive composition forms a conductive layer on one side of the first film. The conductive composition is heat-treated in a drying furnace and dried. In this case, the drying temperature is preferably 40 to 70 ° C. If the drying temperature is lower than 40 캜, drying of the coating film may be insufficient, resulting in poor adhesion and increased resistance, and may require a long time for sufficient drying, resulting in a decrease in productivity. In addition, when the drying temperature exceeds 70 ° C, drying may cause deformation of the coating substrate and deterioration of the function of the binder resin.

In the insulating layer forming step (S20), an insulating layer is formed on one surface of the second film. The second film prevents contamination from the external environment and protects the insulating layer in the lamination step. The second film is characterized in that an adhesive layer is formed between the transparent film and the opaque film. In addition, the second film is the same as the material of the first film, and a description of the thickness of the first film is omitted.

The insulating layer comprises an insulating layer composition comprising 9 to 15 wt% of a binder, 1 to 5 wt% of a curing agent, 35 to 40 wt% of a solvent, and 40 to 55 wt% of a filler. And the insulating layer is 10 to 15 占 퐉. The insulating layer composition is the same as the binder, the curing agent and the solvent of the conductive composition, and a description of the same constitution will be omitted. Therefore, the filler will be described below.

The filler includes a flame retardant filler, an abrasion resistant filler, and a lubricant filler. The filler has a cross section of 1 to 20 mu m. The insulating layer may be formed by using a filler having a thickness larger than that of the insulating layer. The irregularities have an effect of improving adhesion to the conductive layer in the lamination step to be described later.

The flame-retardant filler includes at least one selected from aluminum hydroxide, a phosphorus compound, calcium hydroxide, and zinc hydroxide. The abrasion-resistant filler includes at least one selected from titanium hydroxide, silica, zirconium oxide, and oxidized bottoms. Considering the lubrication effect according to the addition amount, the mixing property with the binder resin composition, the sedimentation prevention property in the binder resin composition, and the increase in the cost due to the addition amount, the lubricant filler is preferably selected from the group consisting of carbon black Carbon black which is made of a material of a kind or more and is particularly easy to disperse the particles and has a particle size of nm is more preferable.

In the lamination step S30, the insulating layer of the second film is positioned on the upper surface of the conductive layer of the first film. At this time, the laminated film upper and lower surfaces are laminated with rollers to produce an electromagnetic wave shielding film having a total thickness of 130 to 190 μm. In the lamination step S30, a rubber roller may be used for the upper and lower portions, or a SUS roller may be used for the upper surface.

Hereinafter, the present invention will be described in more detail with reference to Examples 1 to 2 and Comparative Examples 1 to 3 below.

It should be understood, however, that the invention is not construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It will be apparent to those skilled in the art that the present invention can be changed.

≪ Example 1 >

The conductive composition comprises 10% by weight of silylated epoxy, 1.5% by weight of TPU, 2% by weight of curing agent, 45% by weight of Ag coated copper and 41.5% by weight of DBE (Di Basic Ester) (Silylated 50%) of two rings of the O-cresol Novolac Epoxy are used. The conductive composition was applied to one side of a polyester film having a thickness of 80 탆 to prepare a film having a conductive layer of 11 탆.

In addition, a lubricant filler was added to the conductive composition instead of Ag coated copper to prepare an insulating layer composition. The insulating layer composition was applied to one side of a polyester film having a thickness of 60 탆 to prepare a film having an insulating layer of 14 탆.

An electromagnetic wave pick-up film having a total thickness of 165 mu m was prepared by laminating the insulating films and the conductive layers in the prepared films using a pair of rollers heated to 100 DEG C so that the insulating layer and the conductive layer were opposed to each other.

≪ Example 2 >

Except that one of four rings of an O-cresol Novolac Epoxy having the structure of the formula (1) was silylated (silylation 25%) in Example 1, An electromagnetic wave shielding film was prepared in the same manner as in Example 1.

≪ Comparative Example 1 &

An electromagnetic wave shielding film was produced in the same manner as in Example 1, except that epoxy (Bisphenol-A type basic solid resin, product name: YD-011 made by Kuko Chemical Co., Ltd.) commercially available as a binder was used in Example 1.

≪ Comparative Example 2 &

An electromagnetic wave shielding film was prepared in the same manner as in Example 1, except that epoxy (Bisphenol-A type basic solid resin, product name: YD-012 made by Kukdo Chemical Co., Ltd.) was used as a binder in Example 1.

≪ Comparative Example 3 &

An electromagnetic wave shielding film was prepared in the same manner as in Example 1, except that epoxy (Bisphenol-A type basic solid resin, product name: YD-013K, available from Kukdo Chemical Co., Ltd.) was used as a binder in Example 1.

≪ Comparative Example 4 &

Except that three of four rings of an O-cresol Novolac Epoxy having the structure of Chemical Formula 1 in Example 1 were silylated (silylation 75%). An electromagnetic wave shielding film was prepared in the same manner as in Example 1.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 CTE
(ppm / DEG C) 4.2 10.0 15.0 14.5 17 15.5 Sheet resistance
(Ω / □) 0.5 0.5 0.6 0.4 0.6 0.6 Heat resistance
(Lead 300 ° C, 10 sec floating) pass pass fail
(blister) fail
(blister) fail
(blister) fail
(blister)

Measurement of thermal expansion coefficient

Examples 1 to 2 and Comparative Examples 1 to 4 were used to prepare specimens (10? Cm) of the same size for measuring the thermal expansion coefficient. The thermal expansion coefficient is measured using a TMA (Thermomechanical Analysis). The temperature was increased from 1 STEP to 2 STEP and the temperature was increased from 1 STEP to 250 DEG C, followed by cooling to 30 DEG C and increasing the temperature from 30 DEG C to 250 DEG C at 2 STEP. At this time, the temperature rising rate was 5 ° C / min. Table 1 shows the coefficient of thermal expansion, and FIG. 2 is a graph showing the results of the thermal expansion coefficient test for each temperature.

The bisphenol-A type basic solid resin of the commercial epoxy epoxidation chemistry of Comparative Example 1 had a thermal expansion coefficient of 15 ppm / 占 폚, while Example 1 was 4.2 ppm / 占 폚 and Example 2 was 10 ppm / 占 폚. Lt; / RTI >

Sheet resistance  Measure

Examples 1 to 2 and Comparative Examples 1 to 4 were measured at room temperature in a sheet resistance measuring machine. In Examples 1 and 2, 0.5? / ?, and in Comparative Examples 1 to 4, 0.4? 0.6? / ?. In the above Examples 1 to 2 and Comparative Examples 1 to 4, it was found that there was almost no difference in physical properties as basic items among the basic properties of the film. That is, it can be seen that Examples 1 and 2 of the present invention have substantially no change in physical properties of sheet resistance as compared with Comparative Examples, but have improved shrinkage ratio (see the results of thermal expansion coefficient measurement) and heat resistance.

Heat resistance measurement

Examples 1 to 2 and Comparative Examples 1 to 4 were floated in soldering baths at 300 ° C for 10 seconds, and then blisters and peeling phenomenon were confirmed to evaluate heat resistance. The heat resistance was evaluated as fail when either of the blisters and the peeling phenomenon occurred, and when the both were not present, it was judged as pass. In Examples 1 and 2, there was no blister and peeling, but in Comparative Examples 1 to 4, bubbles were generated.

The electromagnetic wave shielding film according to the present invention includes an epoxy synthesis process which is required to have a low shrinkage ratio and improved heat resistance in a flexible printed circuit board (FPCB), and the synthesized epoxy is applied to the conductive layer and the insulating layer, , The sheet resistance was improved.

Claims (14)

Forming a conductive layer made of a conductive composition comprising 9 to 15% by weight of a binder, 1 to 5% by weight of a curing agent, 35 to 40% by weight of a solvent and 40 to 55% by weight of a conductive powder on one surface of a first film, ;
Forming an insulating layer composed of an insulating layer composition containing 9 to 15% by weight of a binder, 1 to 5% by weight of a curing agent, 35 to 40% by weight of a solvent and 40 to 55% by weight of a filler on one surface of a second film And
And a lamination step of laminating the first film and the second film,
Wherein at least one of a polyester-modified urethane resin, a synthetic epoxy resin, a thermoplastic polyurethane (TPU), and a polyurethane-urea is selected as the binder in the conductive layer and the insulating layer.
The method according to claim 1,
Wherein the synthetic epoxy resin is silylated with an O-cresol novolac epoxy having the structure of formula (S1).
[Formula (S1)

(n is an integer of 1 or more)
3. The method of claim 2,
Wherein the synthetic epoxy resin is silylated with one to two of the four rings of the silylated O-cresol Novolac Epoxy.
The method according to claim 1,
Wherein the synthetic epoxy resin forms an intermediate product of the structure of formula (S2) after stirring the O-cresol novolac epoxy.
≪ RTI ID = 0.0 &

(n is an integer of 1 or more)
5. The method of claim 4,
Wherein the synthetic epoxy resin is an O-cresol Novolac epoxy of formula (S3) wherein 1 to 2 of four rings are silylated in the intermediate product.
[Formula (S3)

(n is an integer of 1 or more)
The method according to claim 1,
Wherein the conductive layer and the binder include a synthetic epoxy resin and a thermoplastic polyurethane (TPU), and when the synthetic epoxy resin is 1, a binder is formed at a ratio of 1: 0.11 to 0.17 Wherein the electromagnetic wave shielding film has a thickness of 10 to 100 nm.
The method according to claim 1,
The solvent is selected from the group consisting of methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl acetate, methyl pyrrolidone, acetone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone (MEK), toluene Dibasic Ester) or an aqueous solution in which they are mixed with water.
The method according to claim 1,
The step of forming the insulating layer may be performed by using a filler having a thickness larger than the thickness of the insulating layer,
Wherein the lamination step comprises laminating the conductive layer so that the conductive layer is positioned on the uneven surface of the insulating layer.
9. An electromagnetic wave shielding film produced by the method of any one of claims 1 to 8.
10. The method of claim 9,
Wherein the electromagnetic wave shielding film has a thickness of 130 to 190 mu m in which the conductive layer formed on one surface of the first film and the insulating layer formed on one surface of the second film are laminated adjacent to each other.
10. The method of claim 9,
Wherein the electromagnetic wave shielding film has a thickness of 10 to 15 占 퐉.
10. The method of claim 9,
Wherein the electromagnetic wave shielding film has a thickness of the insulating layer of 10 to 15 占 퐉.
13. The method of claim 12,
Wherein the insulating layer has a cross-section of 1 to 20 占 퐉 in the filler.
10. The method of claim 9,
Wherein the electromagnetic wave shielding film has a thermal expansion coefficient of 4 to 10 ppm / 占 폚.

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