Electromagnetic wave shielding film, method for producing same, printed wiring board with electromagnetic wave shielding film, and method for producing same

Abstract

The invention relates to an electromagnetic wave shielding film and a manufacturing method thereof, and a printed wiring board with the electromagnetic wave shielding film and a manufacturing method thereof. More specifically, the present invention provides an electromagnetic wave shielding film capable of improving the adhesion between an insulating resin layer and a conductive layer even if the heat resistance of the insulating resin layer is improved. This electromagnetic wave shielding film (1) has an insulating resin layer (10), a conductive layer (30), and an anchor coat layer (20) formed between the insulating resin layer (10) and the conductive layer (30), the anchor coat layer (20) having a thickness of 1-500 nm (inclusive) and containing a resin having a glass transition temperature of 40-105 DEG C (inclusive).

Description

[0001] This application is a divisional application based on the Chinese invention patent application with application number 201910978794.1, application date October 15, 2019, and invention name "Electromagnetic wave shielding film and its manufacturing method, and printed circuit board with electromagnetic wave shielding film and its manufacturing method". Technical Field

[0002] The present invention relates to an electromagnetic wave shielding film and a method for producing the same, and a printed wiring board with the electromagnetic wave shielding film and a method for producing the same. Background Art

[0003] In order to shield electromagnetic noise from the outside and prevent leakage of electromagnetic noise generated from the printed wiring board, an electromagnetic shielding film having an insulating resin layer and a conductive layer is sometimes provided on the surface of the printed wiring board via an insulating film (cover film) (for example, see Patent Document 1). Electromagnetic wave shielding films are manufactured, for example, by applying a coating containing a thermosetting resin, a curing agent, and a solvent to one side of a carrier film, drying the coating to form an insulating resin layer, and then providing a conductive layer on the surface of the insulating resin layer. As the conductive layer, for example, a conductive layer comprising a metal thin film layer and a conductive adhesive layer is sometimes used. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-086120 Summary of the Invention

[0005] Electromagnetic shielding films are sometimes used in high-temperature environments. Therefore, high heat resistance is sometimes required. To meet this requirement, a resin with a high glass transition temperature is sometimes used to form the insulating resin layer, thereby increasing the crosslinking degree of the resin. However, if a resin with a high glass transition temperature is used as the resin constituting the insulating resin layer and the crosslinking degree of the resin is increased, the adhesion between the insulating resin layer and the conductive layer tends to decrease. In particular, when the conductive layer includes a metal thin film layer and the insulating resin layer and the metal thin film layer are in contact, the adhesion between the insulating resin layer and the conductive layer tends to decrease more. An object of the present invention is to provide an electromagnetic wave shielding film and a method for producing the same, and a printed wiring board with the electromagnetic wave shielding film and a method for producing the same, which can improve the adhesion between the insulating resin layer and the conductive layer even if the heat resistance of the insulating resin layer is improved. The present invention includes the following aspects. [1] An electromagnetic wave shielding film comprising an insulating resin layer, a conductive layer, and an anchor coating layer formed between the insulating resin layer and the conductive layer, wherein the anchor coating layer has a thickness of 1 nm to 500 nm and contains a resin having a glass transition temperature of 40° C. to 105° C. [2] The electromagnetic wave shielding film according to [1], wherein the resin contained in the anchor coating layer has an ester bond. [3] The electromagnetic wave shielding film according to [1] or [2], wherein the resin contained in the anchor coating layer is a polyester resin. [4] The electromagnetic wave shielding film according to any one of [1] to [3], wherein the resin contained in the anchor coating layer has a urethane bond. [5] The electromagnetic wave shielding film according to any one of [1] to [4], wherein the insulating resin contained in the insulating resin layer has at least one of a hydroxyl group, an amino group, an amide group, a carboxyl group, a mercapto group, and an epoxy group. [6] The electromagnetic wave shielding film according to any one of [1] to [5], wherein the conductive layer includes a metal thin film layer, and the metal thin film layer is in contact with the anchor coating layer. [7] The electromagnetic wave shielding film according to [6], wherein the conductive layer further includes a conductive adhesive layer on the surface of the metal thin film layer opposite to the anchor coating layer. [8] The electromagnetic wave shielding film according to any one of [1] to [7], further comprising a carrier film on the surface of the insulating resin layer opposite to the anchor coating layer. [9] A printed circuit board with an electromagnetic wave shielding film, comprising: A printed circuit board having a printed circuit provided on at least one side of a substrate; an insulating film adjacent to a surface of the printed wiring board on which the printed circuit is provided; and the electromagnetic wave shielding film according to any one of [1] to [8], wherein the conductive layer is provided adjacent to the insulating film.

[10] A method for manufacturing an electromagnetic wave shielding film, wherein a resin having a glass transition temperature of not less than 40°C and not more than 105°C is contained on one side of an insulating resin layer, an anchor coating having a thickness of not less than 1 nm and not more than 500 nm is formed, and a conductive layer is formed on the opposite side of the anchor coating to the insulating resin layer.

[11] The method for producing an electromagnetic wave shielding film according to

[10] , wherein, when forming the anchor coat layer, a thermosetting resin is reacted with a curing agent for forming the anchor coat layer.

[12] The method for producing an electromagnetic wave shielding film according to

[11] , wherein the thermosetting resin is a polyester resin.

[13] The method for producing an electromagnetic wave shielding film according to

[11] or

[12] , wherein the anchor coat layer-forming curing agent is a compound having two or more isocyanate groups.

[14] The method for manufacturing an electromagnetic wave shielding film according to

[13] , wherein the molar ratio of the amount of isocyanate groups in the anchor coat-forming curing agent to the amount of reactive groups in the thermosetting resin is 1.3 or more and 20 or less. The molar ratio of the amount of isocyanate groups in the anchor coating layer-forming curing agent to the amount of reactive groups in the thermosetting resin is preferably 1.1 or more and 20 or less.

[15] A method for manufacturing an electromagnetic wave shielding film according to any one of

[10] to

[14] , wherein, when forming the anchor coating layer, a coating containing a thermosetting resin and a curing agent for forming the anchor coating layer is applied to the insulating resin layer and cured.

[16] The method for manufacturing an electromagnetic wave shielding film according to any one of

[10] to

[15] , wherein, when forming the conductive layer, a metal thin film layer is formed on the surface of the anchor coating layer opposite to the insulating resin layer.

[17] The method for manufacturing an electromagnetic wave shielding film according to

[16] , wherein the metal thin film layer is formed by vacuum evaporation.

[18] The method for manufacturing an electromagnetic wave shielding film according to

[17] , wherein, when forming the conductive layer, a conductive adhesive layer is further formed on the surface of the metal thin film layer opposite to the anchor coating layer.

[19] The method for producing an electromagnetic wave shielding film according to any one of

[10] to

[18] , wherein, when forming the insulating resin layer, an epoxy resin is reacted with a curing agent for forming the insulating resin layer.

[20] The method for producing an electromagnetic wave shielding film according to

[19] , wherein the curing agent for forming the insulating resin layer is an amine compound.

[21] The method for producing an electromagnetic shielding film according to

[20] , wherein the amine compound is an aliphatic amine compound.

[22] A method for manufacturing a printed circuit board with an electromagnetic wave shielding film, wherein a printed circuit board having a printed circuit provided on at least one side of a substrate and the electromagnetic wave shielding film described in any one of [1] to [8] are crimped together via an insulating film, and during the crimping, the conductive layer of the electromagnetic wave shielding film is brought into close contact with the insulating film.

[0006] The electromagnetic wave shielding film of the present invention can improve the adhesion between the insulating resin layer and the conductive layer even if the heat resistance is improved by using the insulating resin layer having a high glass transition temperature and a high crosslinking density. According to the method for producing an electromagnetic wave shielding film of the present invention, the above-mentioned electromagnetic wave shielding film can be easily produced. The printed wiring board with an electromagnetic wave shielding film of the present invention can improve the adhesion between the insulating resin layer and the conductive layer even if the heat resistance is improved by using an insulating resin layer having a high glass transition temperature and a high crosslinking density. The method for manufacturing a printed circuit board with an electromagnetic wave shielding film according to the present invention can easily manufacture the printed circuit board with an electromagnetic wave shielding film. Since the heat resistance of the insulating resin layer can be improved, strong thermocompression bonding can be performed, thereby improving the yield rate of the printed circuit board with an electromagnetic wave shielding film. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a cross-sectional view showing a first embodiment of the electromagnetic shielding film of the present invention. Figure 2 This is a cross-sectional view showing a second embodiment of the electromagnetic shielding film of the present invention. Figure 3 It is a cross-sectional view showing a third embodiment of the electromagnetic shielding film of the present invention. Figure 4 This is a cross-sectional view showing one embodiment of the printed wiring board with an electromagnetic wave shielding film of the present invention. Figure 5 Yes Figure 4 A cross-sectional view of the manufacturing process of a printed wiring board with an electromagnetic wave shielding film. DETAILED DESCRIPTION

[0008] The following definitions of terms apply throughout this specification and claims. The “isotropic conductive adhesive layer” refers to a conductive adhesive layer having conductivity in the thickness direction and the surface direction. The “anisotropic conductive adhesive layer” refers to a conductive adhesive layer that has conductivity in the thickness direction but has no conductivity in the surface direction. The “conductive adhesive layer having no conductivity in the surface direction” means that the surface resistance is 1×10 4 Conductive adhesive layer with a resistance of Ω or more. The average particle size is determined by randomly selecting 30 particles from a microscopic image of the particles, measuring the minimum and maximum diameters of each particle, and taking the median of the minimum and maximum diameters as the particle size of the particle. The arithmetic mean of the 30 measured particle sizes is then calculated. The same applies to the average particle size of the conductive particles. The thickness of films (release films, insulating films, etc.) is measured at five locations using a contact-type film thickness gauge and the average value is obtained. The thickness of anchor coatings is measured using an interference-type film thickness gauge. The thickness of insulating resin layers, conductive adhesive layers, metal thin film layers, etc. is measured at five locations using a microscope to observe the cross-section of the measurement object and the average value is obtained. The storage elastic modulus is calculated from the stress applied to the measurement object and the detected strain, and is measured as one of the viscoelastic properties using a dynamic viscoelasticity measurement device that outputs the output as a function of temperature or time. The 10% compressive strength of the conductive fine particles was determined by the following formula (α) from the measurement results obtained using a micro-compression tester. C(x)=2.48P / πd 2 (α) Here, C(x) is the 10% compressive strength (MPa), P is the test force (N) at 10% displacement of the particle size, and d is the particle size (mm). The surface resistivity is a value determined based on JIS K 7194 or JIS K 6911. Figures 1 to 5 The size ratios in the figure are for convenience of explanation and may differ from the actual size ratios.

[0009] <Electromagnetic wave shielding film> One embodiment of the electromagnetic shielding film of the present invention will be described. The electromagnetic shielding film of this embodiment includes an insulating resin layer, a conductive layer, and an anchor coating layer formed between the insulating resin layer and the conductive layer.

[0010] Figure 1 : is a cross-sectional view showing the electromagnetic shielding film 1 according to the first embodiment. Figure 2 : is a cross-sectional view showing an electromagnetic shielding film 1 according to a second embodiment. Figure 3 It is a cross-sectional view showing an electromagnetic shielding film 1 according to a third embodiment. The electromagnetic wave shielding film 1 of the first embodiment, the second embodiment and the third embodiment all have: an insulating resin layer 10, an anchor coating 20 adjacent to the insulating resin layer 10, a conductive layer 30 adjacent to the side of the anchor coating 20 opposite to the insulating resin layer 10, a carrier film 40 adjacent to the side of the insulating resin layer 10 opposite to the anchor coating 20, and a release film 50 adjacent to the side of the conductive layer 30 opposite to the anchor coating 20. The conductive layer 30 of the electromagnetic wave shielding film 1 of the first embodiment includes a metal thin film layer 32 adjacent to the anchor coating layer 20 and an anisotropic conductive adhesive layer 34 adjacent to the release film 50 . The conductive layer 30 of the electromagnetic wave shielding film 1 of the second embodiment includes a metal thin film layer 32 adjacent to the anchor coating layer 20 and an isotropic conductive adhesive layer 36 adjacent to the release film 50 . The conductive layer 30 of the electromagnetic shielding film 1 of the third embodiment is composed of an isotropic conductive adhesive layer 36 .

[0011] (Insulating resin layer) The insulating resin layer 10 is a resin layer that functions as a protective layer for the conductive layer 30 . Examples of insulating resin layer 10 include a coating film formed by applying a coating containing a thermosetting resin and a curing agent for forming the insulating resin layer, and semi-curing or curing the coating; a coating film formed by applying a coating containing a thermoplastic resin; and a layer composed of a film formed by melt-molding a composition containing a thermoplastic resin. From the perspective of heat resistance during welding, etc., insulating resin layer 10 is preferably a coating film formed by applying a coating containing a thermosetting resin and a curing agent for forming the insulating resin layer, and semi-curing or curing the coating. Therefore, the resin contained in insulating resin layer 10 is preferably a cured product of a thermosetting resin, for greater heat resistance. The cured product herein also includes a semi-cured product.

[0012] As the thermosetting resin, for example, epoxy resin, amide resin, polyester resin, phenolic resin, amino resin, alkyd resin, polyurethane resin, synthetic rubber, ultraviolet curing acrylate resin etc. can be enumerated. One thermosetting resin can be used alone or in combination of two or more. Among the thermosetting resins, epoxy resin is preferred because of its excellent heat resistance and excellent chemical resistance. Examples of curing agents for forming the insulating resin layer include known curing agents corresponding to the type of thermosetting resin. When the thermosetting resin is an epoxy resin, an amine compound is preferably used as the curing agent for forming the insulating resin layer. Curing of epoxy resin using an amine compound can moderately lower the reaction temperature and fully crosslink the epoxy resin for curing, further improving the heat resistance of the insulating resin layer 10. Examples of the amine compound used as a curing agent for forming the insulating resin layer include aliphatic amine compounds, aromatic amine compounds, and heterocyclic amine compounds. Examples of the aliphatic amine compound include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, N-aminoethylpiperazine, Menthene diamine, isophorone diamine, meta-xylene diamine, etc. Examples of the aromatic amine compound include m-phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of the heterocyclic amine compound include imidazole, 2-methylimidazole, and 2-ethyl-4-methylimidazole. When epoxy resin is used as a thermosetting resin, an aliphatic amine compound is preferably used as a curing agent for forming the insulating resin layer. When epoxy resin is used as a thermosetting resin and an aliphatic amine compound is used as a curing agent for forming the insulating resin layer, the epoxy ring opens during curing to form a large number of hydroxyl groups. This readily reacts with the components that constitute the anchor coating 20, further improving the adhesion between the insulating resin layer 10 and the anchor coating 20. In particular, when a polyisocyanate having two or more isocyanate groups is used as a component that forms the anchor coating 20, the isocyanate groups of the polyisocyanate react with the hydroxyl groups in the insulating resin layer 10. Consequently, the adhesion between the insulating resin layer 10 and the anchor coating 20 is further improved. The insulating resin layer-forming curing agent such as the amine compound may be used alone or in combination of two or more.

[0013] In order to conceal the printed circuit of the flexible printed wiring board or to impart design characteristics to the printed wiring board with an electromagnetic wave shielding film, the insulating resin layer 10 may contain either or both of a colorant (pigment, dye, etc.) and a filler. As either or both of the colorant and filler, from the viewpoints of weather resistance, heat resistance, and concealability, a pigment or a filler is preferred. From the viewpoints of concealability and design of the printed circuit, a black pigment or a combination of a black pigment and other pigments or fillers is more preferred.

[0014] The insulating resin layer 10 may contain a flame retardant. The insulating resin layer 10 may contain other components as needed within a range that does not impair the effects of the present invention.

[0015] The storage elastic modulus of the insulating resin layer 10 at 180°C is preferably 5×10 5 Pa or more and 5×10 9 Pa or less, more preferably 1×10 6 Pa and 1×10 9 Pa or less. If the storage elastic modulus of the insulating resin layer 10 at 180°C is greater than the lower limit of the above range, the insulating resin layer 10 has a moderate hardness, which can reduce the pressure loss in the insulating resin layer 10 during hot pressing. As a result, the electromagnetic wave shielding film 1 can be prevented from breaking during hot pressing, and the shielding characteristics can be prevented from being reduced. If the storage elastic modulus of the insulating resin layer 10 at 180°C is less than the upper limit of the above range, the flexibility of the electromagnetic wave shielding film 1 is improved. As a result, the electromagnetic wave shielding film 1 can be easily sunk into the through-holes of the insulating film 70, and the conductive adhesive layer can be more reliably electrically connected to the printed circuit of the flexible printed wiring board through the through-holes of the insulating film.

[0016] From the viewpoint of electrical insulation, the surface resistance of the insulating resin layer 10 is preferably 1×10 6 Ω or more. From a practical point of view, the surface resistance of the insulating resin layer 10 is preferably 1×10 16 When the surface resistance of the insulating resin layer 10 is equal to or greater than the lower limit of the above range, short circuits caused by contact with other circuits or the like can be prevented. The thickness of the insulating resin layer 10 is preferably from 0.1 μm to 30 μm, more preferably from 0.5 μm to 20 μm. When the thickness of the insulating resin layer 10 is at least the lower limit of the above range, the insulating resin layer 10 can fully function as a protective layer. When the thickness of the insulating resin layer 10 is at most the upper limit of the above range, the electromagnetic wave shielding film 1 can be made thinner.

[0017] (Anchor coating) The anchor coating layer 20 is a resin layer that improves the adhesion between the insulating resin layer 10 and the conductive layer 30. Hereinafter, the resin contained in the anchor coating layer 20 is referred to as "anchor coating resin." The glass transition temperature (Tg) of the anchor coating resin is 40°C to 105°C, preferably 50°C to 100°C. The glass transition temperature of the resin is the ratio of the loss modulus E" to the storage modulus E' (E" / E') determined by dynamic viscoelasticity measurement, that is, the temperature at which tan δ reaches its peak. By setting the glass transition temperature of the anchor coating resin to be above the aforementioned lower limit, a decrease in heat resistance can be suppressed. By setting the glass transition temperature of the anchor coating resin to be below the aforementioned upper limit, the anchor coating layer 20 more closely follows the surface shape of the conductive layer 30 during formation, thereby improving the adhesion between the insulating resin layer 10 and the conductive layer 30.

[0018] The anchor coating resin may be a cured product of a thermosetting resin or a thermoplastic resin. From the perspective of further improving the heat resistance of the electromagnetic wave shielding film 1, the anchor coating resin is preferably a cured product of a thermosetting resin. The thermosetting resin may be the same as the thermosetting resin used to form the insulating resin layer 10. The anchor coating resin may be a cured product of a thermosetting resin or a thermoplastic resin, and preferably has an ester bond. Since ester bonds have high polarity, the anchor coating resin having an ester bond further improves adhesion to the conductive layer containing metal. Resins having ester bonds are preferably polyester resins or polycarbonate polyols, with polyester resins being more preferred. The glass transition temperature of polyester resins is likely to be within the above-mentioned range, further improving the adhesion between the anchor coating layer 20 and the conductive layer 30. Polyester resins are mostly thermoplastic resins, but since they often have hydroxyl groups at the ends, they can also be thermosetting resins. Unsaturated polyester resins can also be used as thermosetting polyester resins. The anchor coating resin is particularly preferably a cross-linked polyester resin.

[0019] When the anchor coating layer 20 is a cured product of a thermosetting resin, the cured product is a reaction product obtained by reacting the thermosetting resin with a curing agent for forming the anchor coating layer. The cured product obtained by reacting the thermosetting resin with the curing agent for forming the anchor coating layer undergoes crosslinking to form a polymer, thereby further improving heat resistance, chemical resistance, and other properties, thereby enhancing resistance to various environments. The anchor coating-forming curing agent is selected based on the type of thermosetting resin. When a polyester resin is used as the thermosetting resin, a polyisocyanate compound having two or more isocyanate groups is preferably used as the anchor coating-forming curing agent. Crosslinking and curing the polyester resin with a polyisocyanate compound can form a crosslinked polyester resin with higher heat resistance, further improving the heat resistance of the electromagnetic wave shielding film 1 and further enhancing adhesion by forming urethane bonds with excellent metal adhesion.

[0020] The thickness of the anchor coating layer 20 is from 1 nm to 500 nm, preferably from 10 nm to 300 nm. By setting the thickness of the anchor coating layer 20 to be greater than the lower limit, the insulating resin layer 10 is well sunk into the conductive layer 30, thereby further improving the adhesion between the insulating resin layer 10 and the conductive layer 30. By setting the thickness of the anchor coating layer 20 to be less than the upper limit, a decrease in heat resistance can be suppressed.

[0021] (Conductive layer) The conductive layer contains at least metal and is a layer that shields electromagnetic waves. Specifically, as described above, the conductive layer 30 in the first embodiment includes the metal thin film layer 32 adjacent to the anchor coating layer 20 and the anisotropic conductive adhesive layer 34 adjacent to the release film 50 . The conductive layer 30 in the second embodiment includes a metal thin film layer 32 adjacent to the anchor coating layer 20 and an isotropic conductive adhesive layer 36 adjacent to the release film 50 . The conductive layer 30 in the third embodiment is composed of an isotropic conductive adhesive layer 36 . From the perspective of sufficiently improving electromagnetic wave shielding properties, the conductive layer 30 preferably includes a metal thin film layer 32 and an anisotropic conductive adhesive layer 34 or an isotropic conductive adhesive layer 36. In other words, the conductive layer 30 preferably includes both a metal thin film layer and a conductive adhesive layer.

[0022] [Metal thin film layer] The metal thin film layer 32 is a layer composed of a metal thin film. The metal thin film layer 32 is formed so as to extend in the surface direction, and therefore has conductivity in the surface direction, and functions as an electromagnetic wave shielding layer or the like.

[0023] Examples of the metal thin film layer 32 include a vapor-deposited film formed by physical vapor deposition (vacuum vapor deposition, sputtering, ion beam vapor deposition, electron beam vapor deposition, etc.) or chemical vapor deposition, a plated film formed by plating, and metal foil. The metal thin film layer 32 is preferably a vapor-deposited film or a plated film because it has high air permeability, allows the gas generated during reflow to pass through without expanding, and can be easily formed. The metal thin film layer 32 is more preferably a vapor-deposited film, and more preferably a vapor-deposited film based on physical vapor deposition, because it can make the conductive layer 30 thinner, and even if the thickness is thinner, the conductivity in the surface direction is excellent, and it can be easily formed by a dry process.

[0024] Examples of the metal constituting the metal thin film layer 32 include aluminum, silver, copper, gold, and conductive ceramics. From the viewpoint of electrical conductivity, silver or copper is preferred. Among the metal thin film layers 32 , from the viewpoint of high electromagnetic wave shielding properties and ease of forming the metal thin film layer, a metal vapor-deposited layer is preferred, and a silver vapor-deposited layer or a copper vapor-deposited layer is more preferred.

[0025] The surface resistance of the metal thin film layer 32 is preferably 0.001Ω to 1Ω, more preferably 0.001Ω to 0.5Ω. If the surface resistance of the metal thin film layer 32 is at least the lower limit of the above range, the metal thin film layer 32 can be sufficiently thinned. If the surface resistance of the metal thin film layer 32 is at most the upper limit of the above range, the metal thin film layer 32 can fully function as an electromagnetic wave shielding layer.

[0026] The thickness of the metal thin film layer 32 is preferably from 0.01 μm to 5 μm, more preferably from 0.05 μm to 3.5 μm. When the thickness of the metal thin film layer 32 is 0.01 μm or greater, the surface conductivity is further improved. When the thickness of the metal thin film layer 32 is 0.05 μm or greater, the shielding effect of electromagnetic noise is further improved. When the thickness of the metal thin film layer 32 is below the upper limit of the above range, the electromagnetic wave shielding film 1 can be made thinner. In addition, the productivity and flexibility of the electromagnetic wave shielding film 1 are improved.

[0027] [Anisotropic conductive adhesive layer] The anisotropic conductive adhesive layer 34 in the first embodiment has conductivity in the thickness direction, has no conductivity in the surface direction, and has adhesiveness. The anisotropic conductive adhesive layer 34 can easily reduce the thickness of the conductive adhesive layer and reduce the amount of conductive particles described below. As a result, it has the advantage of reducing the thickness of the electromagnetic shielding film 1 and increasing the flexibility of the electromagnetic shielding film 1 .

[0028] The anisotropic conductive adhesive layer 34 is preferably a thermosetting conductive adhesive layer from the viewpoint of exhibiting heat resistance after curing. The thermosetting anisotropic conductive adhesive layer 34 may be in an uncured state or in a B-stage state. The thermosetting anisotropic conductive adhesive layer 34 includes, for example, a thermosetting adhesive 34a and conductive particles 34b. The thermosetting anisotropic conductive adhesive layer 34 may also include a flame retardant as needed.

[0029] As the thermosetting adhesive 34a, epoxy resin, phenolic resin, amino resin, alkyd resin, polyurethane resin, synthetic rubber, ultraviolet curing acrylate resin etc. can be mentioned. From the viewpoint of excellent heat resistance, epoxy resin is preferred. Epoxy resin can also include a rubber component (carboxyl modified nitrile rubber, acrylic rubber, etc.) for imparting flexibility, a tackifier etc. The thermosetting adhesive 34a may contain cellulose resin or microfibrils (glass fibers, etc.) to increase the strength of the anisotropic conductive adhesive layer 34 and improve the punching properties. The thermosetting adhesive may contain other components as needed without impairing the effects of the present invention.

[0030] Examples of the conductive fine particles 34b include particles of metals (silver, platinum, gold, copper, nickel, palladium, aluminum, solder, etc.), graphite powder, calcined carbon particles, plated calcined carbon particles, etc. The conductive particles 34b are preferably metal particles, and more preferably copper particles, from the viewpoint of imparting a suitable hardness to the anisotropic conductive adhesive layer 34 and further reducing the pressure loss of the anisotropic conductive adhesive layer 34 during hot pressing.

[0031] The 10% compressive strength of the conductive particles 34b is preferably 30 MPa to 200 MPa, more preferably 50 MPa to 150 MPa, and even more preferably 70 MPa to 100 MPa. When the 10% compressive strength of the conductive particles is at least the lower limit of the aforementioned range, the pressure applied to the metal thin film layer 32 during hot pressing is not significantly reduced, allowing the anisotropic conductive adhesive layer 34 to be more reliably electrically connected to the printed circuit of the printed wiring board through the through-holes in the insulating film. When the 10% compressive strength of the conductive particles 34b is at most the upper limit of the aforementioned range, contact with the metal thin film layer 32 is improved, resulting in a reliable electrical connection.

[0032] The average particle size of the conductive particles 34b in the anisotropic conductive adhesive layer 34 is preferably 1 μm or more and 26 μm or less, more preferably 2 μm or more and 16 μm or less. When the average particle size of the conductive particles 34b is at least the lower limit of the above range, the thickness of the anisotropic conductive adhesive layer 34 can be ensured, and sufficient bonding strength can be achieved. When the average particle size of the conductive particles 34b is at most the upper limit of the above range, the fluidity of the anisotropic conductive adhesive layer 34 can be ensured. As described later, when the anisotropic conductive adhesive layer 34 is pushed into the through-holes of the insulating film, the conductive adhesive can be fully filled into the through-holes of the insulating film.

[0033] The proportion of the conductive particles 34b in the anisotropic conductive adhesive layer 34 is preferably 0.5% by volume or more and 30% by volume or less, and more preferably 1% by volume or more and 15% by volume or less, based on 100% by volume of the anisotropic conductive adhesive layer 34. If the proportion of the conductive particles 34b is greater than the lower limit of the above range, the conductivity of the anisotropic conductive adhesive layer 34 is good. If the proportion of the conductive particles 34b is less than the upper limit of the above range, the adhesion and fluidity (the ability to follow the shape of the through-holes in the insulating film) of the anisotropic conductive adhesive layer 34 are good. In addition, the flexibility of the electromagnetic wave shielding film 1 is improved.

[0034] The storage elastic modulus of the anisotropic conductive adhesive layer 34 at 180°C is preferably 1×10 3 Pa or more and 5×10 7 Pa or less, more preferably 5×10 3 Pa or more and 1×10 7Pa or less. If the storage elastic modulus of the anisotropic conductive adhesive layer 34 at 180°C is greater than the lower limit of the above range, the anisotropic conductive adhesive layer 34 further has an appropriate hardness, which can reduce the pressure loss of the conductive adhesive layer during hot pressing. As a result, the conductive adhesive layer is sufficiently adhered to the printed circuit of the printed wiring board, and the anisotropic conductive adhesive layer 34 is more reliably electrically connected to the printed circuit of the printed wiring board through the through-holes of the insulating film. If the storage elastic modulus of the conductive adhesive layer at 180°C is less than the upper limit of the above range, the flexibility of the electromagnetic wave shielding film 1 is good. As a result, the electromagnetic wave shielding film 1 easily sinks into the through-holes of the insulating film, and the anisotropic conductive adhesive layer 34 is more reliably electrically connected to the printed circuit of the printed wiring board through the through-holes of the insulating film.

[0035] The surface resistance of the anisotropic conductive adhesive layer 34 is preferably 1×10 4 Ω or more and 1×10 16 Ω or less, more preferably 1×10 6 Ω or more and 1×10 14 Ω or less. If the surface resistance of the anisotropic conductive adhesive layer 34 is at least the lower limit of the above range, the content of the conductive particles 34b is slightly suppressed. If the surface resistance of the anisotropic conductive adhesive layer 34 is at most the upper limit of the above range, there are no practical or anisotropic problems.

[0036] The thickness of the anisotropic conductive adhesive layer 34 is preferably from 1 μm to 25 μm, more preferably from 2 μm to 15 μm. When the thickness of the anisotropic conductive adhesive layer 34 is at least the lower limit of the above range, the fluidity (adaptability to the shape of the through-holes in the insulating film) of the anisotropic conductive adhesive layer 34 can be ensured, allowing the conductive adhesive to fully fill the through-holes in the insulating film. When the thickness of the anisotropic conductive adhesive layer 34 is at most the upper limit of the above range, the electromagnetic wave shielding film 1 can be made thinner. Furthermore, the flexibility of the electromagnetic wave shielding film 1 is improved.

[0037] [Isotropic conductive adhesive layer] The isotropic conductive adhesive layer 36 in the second embodiment or the third embodiment has conductivity in the thickness direction and the surface direction, and has adhesiveness. The isotropic conductive adhesive layer 36 has an advantage of being able to further improve the electromagnetic wave shielding property of the electromagnetic wave shielding film 1 .

[0038] The isotropic conductive adhesive layer 36 is preferably a thermosetting conductive adhesive layer from the viewpoint of exhibiting heat resistance after curing. The thermosetting isotropic conductive adhesive layer 36 may be in an uncured state or in a B-stage state. The thermosetting isotropic conductive adhesive layer 36 contains, for example, a thermosetting adhesive 36a and conductive particles 36b. The thermosetting isotropic conductive adhesive layer 36 may contain a flame retardant as needed. The components of the thermosetting adhesive 36 a and the material of the conductive particles 36 b included in the isotropic conductive adhesive layer 36 are the same as the components of the thermosetting adhesive 34 a and the material of the conductive particles 34 b included in the anisotropic conductive adhesive layer 34 .

[0039] The average particle size of the conductive particles 36b in the isotropic conductive adhesive layer 36 is preferably 0.1 μm to 10 μm, more preferably 0.2 μm to 1 μm. When the average particle size of the conductive particles 36b is at least the lower limit of the above range, the number of contact points of the conductive particles 36b increases, thereby stably improving three-dimensional conductivity. When the average particle size of the conductive particles 36b is at most the upper limit of the above range, the fluidity of the isotropic conductive adhesive layer 36 (its ability to conform to the shape of the through-holes in the insulating film) is maintained, allowing the conductive adhesive to fully fill the through-holes in the insulating film.

[0040] The proportion of the conductive particles 36b in the isotropic conductive adhesive layer 36 is preferably 50% by volume or more and 80% by volume or less, and more preferably 60% by volume or more and 70% by volume or less, based on 100% by volume of the isotropic conductive adhesive layer 36. If the proportion of the conductive particles 36b is greater than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 36 is excellent. If the proportion of the conductive particles 36b is less than the upper limit of the above range, the adhesion and fluidity (the ability to follow the shape of the through-holes in the insulating film) of the isotropic conductive adhesive layer 36 are excellent. In addition, the flexibility of the electromagnetic wave shielding film 1 is improved.

[0041] The storage elastic modulus of the isotropic conductive adhesive layer 36 at 180°C is preferably 1×10 3 Pa or more and 5×10 7 Pa or less, more preferably 5×10 3 Pa or more and 1×10 7 Pa or less. The reason why the above range is preferred is the same as that for the anisotropic conductive adhesive layer 34 .

[0042] The surface resistance of the isotropic conductive adhesive layer 36 is preferably greater than or equal to 0.05Ω and less than or equal to 2.0Ω, and more preferably greater than or equal to 0.1Ω and less than or equal to 1.0Ω. If the surface resistance of the isotropic conductive adhesive layer 36 is greater than or equal to the lower limit of the above range, the content of the conductive particles 36b is suppressed to a low level, the viscosity of the conductive adhesive becomes too high, and the coating property is better. In addition, the fluidity of the isotropic conductive adhesive layer 36 (the ability to follow the shape of the through-hole of the insulating film) can be further ensured. If the surface resistance of the isotropic conductive adhesive layer 36 is less than or equal to the upper limit of the above range, the entire surface of the isotropic conductive adhesive layer 36 has uniform conductivity.

[0043] The thickness of the isotropic conductive adhesive layer 36 is preferably not less than 1 μm and not more than 20 μm, more preferably not less than 3 μm and not more than 17 μm. If the thickness of the isotropic conductive adhesive layer 36 is not less than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 36 is good, and it can fully function as an electromagnetic wave shielding layer. In addition, the fluidity of the isotropic conductive adhesive layer 36 (the ability to follow the shape of the through-hole of the insulating film) can be ensured, and the inside of the through-hole of the insulating film can be fully buried with the conductive adhesive. It is also possible to ensure folding resistance, and the isotropic conductive adhesive layer 36 will not break even if it is repeatedly bent. If the thickness of the isotropic conductive adhesive layer 36 is not more than the upper limit of the above range, the thin electromagnetic wave shielding film 1 can be made thinner. In addition, the flexibility of the electromagnetic wave shielding film 1 is improved.

[0044] (Carrier film) The carrier film 40 serves as a support that reinforces and protects the insulating resin layer 10 and the conductive layer 30, improving the handling of the electromagnetic wave shielding film 1. In particular, when a thin film, specifically a film with a thickness of 20 μm or less, is used as the insulating resin layer 10, the presence of the carrier film 40 can prevent the insulating resin layer 10 from breaking. After the electromagnetic wave shielding film 1 is attached to a printed wiring board, etc., the carrier film 40 is peeled off from the insulating resin layer 10.

[0045] The carrier film 40 used in the present embodiment includes a carrier film body 42 and an adhesive layer 44 provided on the surface of the carrier film body 42 on the insulating resin layer 10 side.

[0046] Examples of the resin material of the carrier film body 42 include polyethylene terephthalate (hereinafter sometimes referred to as "PET"), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. PET is preferred as the resin material from the viewpoint of heat resistance (dimensional stability) and price when manufacturing the electromagnetic wave shielding film 1.

[0047] The carrier film body 42 may contain either or both of a colorant (pigment, dye, etc.) and a filler. As either or both of the colorant and filler, from the viewpoint of being able to clearly distinguish from the insulating resin layer 10 and making it easy to see the peeling residue (peeling residue) of the carrier film 40 after hot pressing, a pigment of a color different from that of the insulating resin layer 10 is preferred, and a white pigment, a filler, a combination of a white pigment and other pigments, or a combination of a white pigment and a filler is more preferred.

[0048] The storage elastic modulus of the carrier film body 42 at 180°C is preferably 8×10 7 Pa or more and 5×10 9 Pa or less, more preferably 1×10 8 Pa or more and 8×10 8 Pa or less. If the storage elastic modulus of the carrier film body 42 at 180°C is at least the lower limit of the above range, the carrier film 40 has suitable hardness, and the pressure loss of the carrier film 40 during hot pressing can be reduced. If the storage elastic modulus of the carrier film body 42 at 180°C is at most the upper limit of the above range, the carrier film 40 has good flexibility.

[0049] The thickness of the carrier film body 42 is preferably from 3 μm to 100 μm, more preferably from 12 μm to 75 μm. If the thickness of the carrier film body 42 is at least the lower limit of the above range, the electromagnetic wave shielding film 1 will have good handleability. If the thickness of the carrier film body 42 is at most the upper limit of the above range, heat is easily transferred to the conductive adhesive layer (anisotropic conductive adhesive layer 34 or isotropic conductive adhesive layer 36) of the electromagnetic wave shielding film 1 during hot pressing on the surface of the insulating film.

[0050] The adhesive layer 44 is formed, for example, by applying an adhesive composition containing an adhesive to the surface of the carrier film body 42. The adhesive layer 44 provided to the carrier film 40 prevents the carrier film 40 from being peeled off from the insulating resin layer 10 when the release film 50 is peeled off from the conductive adhesive layer or when the electromagnetic wave shielding film 1 is attached to a printed wiring board, etc., by hot pressing. Therefore, the carrier film 40 can fully function as a protective film.

[0051] The adhesive preferably imparts to the adhesive layer 44 moderate adhesiveness to such an extent that the carrier film 40 does not easily peel off from the insulating resin layer 10 before hot pressing and the carrier film 40 can be peeled off from the insulating resin layer 10 after hot pressing. Examples of the adhesive include acrylic adhesives, polyurethane adhesives, and rubber adhesives. The Tg of the adhesive is preferably -100°C to 60°C, and more preferably -60°C to 40°C.

[0052] The thickness of the carrier film 40 is preferably 25 μm to 125 μm, more preferably 38 μm to 100 μm. When the thickness of the carrier film 40 is at least the lower limit of the above range, the electromagnetic shielding film 1 is easily handled. When the thickness of the carrier film 40 is at most the upper limit of the above range, heat is easily transferred to the conductive adhesive layer when hot pressing the conductive adhesive layer of the electromagnetic shielding film 1 onto the surface of the insulating film.

[0053] (Release film) The release film 50 protects the conductive adhesive layer and improves the handleability of the electromagnetic shielding film 1. The release film 50 is peeled from the conductive adhesive layer (anisotropic conductive adhesive layer 34 or isotropic conductive adhesive layer 36) before attaching the electromagnetic shielding film 1 to a printed wiring board or the like. The release film 50 includes, for example, a release film body 52 and a release agent layer 54 provided on the surface of the release film body 52 on the conductive adhesive layer side.

[0054] Examples of the resin material of the release film main body 52 include the same resin materials as those of the carrier film main body 42 . The release film body 52 may contain a colorant, a filler, and the like. The thickness of the release film body 52 is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 150 μm or less, and still more preferably 25 μm or more and 100 μm or less.

[0055] The release agent layer 54 is formed by treating the surface of the release film body 52 with a release agent. The release agent layer 54 facilitates the release of the release film 50 from the conductive adhesive layer when the release film 50 is peeled off, and the conductive adhesive layer is less likely to break. A known release agent can be used as the release agent.

[0056] The thickness of the release agent layer 54 is preferably 0.05 μm to 30 μm, more preferably 0.1 μm to 20 μm. When the thickness of the release agent layer 54 is within the above range, the release film 50 can be peeled off more easily.

[0057] (Thickness of electromagnetic wave shielding film) The thickness of the electromagnetic wave shielding film 1 (excluding the carrier film 40 and the release film 50) is preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less. If the thickness of the electromagnetic wave shielding film 1 excluding the carrier film 40 and the release film 50 is at least the lower limit of the above range, the electromagnetic wave shielding film 1 is less likely to break when the carrier film 40 is peeled off. If the thickness is at most the upper limit of the above range, the printed wiring board with the electromagnetic wave shielding film can be made thinner.

[0058] <Method for producing electromagnetic wave shielding film> As a method of manufacturing the electromagnetic wave shielding film of 1st Embodiment, the following method (A1), method (A2), method (A3), or method (A4) is mentioned, for example. As a method of manufacturing the electromagnetic shielding film of 2nd embodiment, the following method (B1), method (B2), method (B3), or method (B4) is mentioned, for example. As a method of manufacturing the electromagnetic wave shielding film of 3rd embodiment, the following method (C1), method (C2), or method (C3) is mentioned, for example.

[0059] Specifically, the method (A1) is a method having the following steps (A1-1) to (A1-5). Step (A1-1): a step of forming the insulating resin layer 10 on one surface of the carrier film 40 . Step (A1-2): a step of forming the anchor coating layer 20 on the surface of the insulating resin layer 10 facing the carrier film 40 . Step (A1-3): a step of forming the metal thin film layer 32 on the surface of the anchor coating layer 20 facing the insulating resin layer 10 . Step (A1-4): a step of forming an anisotropic conductive adhesive layer 34 on the surface of the metal thin film layer 32 that faces the anchor coating layer 20 . Step (A1-5): A step of laminating the release film 50 on the surface of the anisotropic conductive adhesive layer 34 that faces the metal thin film layer 32 . Hereinafter, each step of method (A1) will be described in detail.

[0060] As a method for forming the insulating resin layer 10 in the step (A1-1), the following method can be mentioned, for example. A method in which a coating material for forming an insulating resin layer containing a thermosetting resin and a curing agent for forming an insulating resin layer is applied to the adhesive layer 44 side surface of the carrier film 40 and semi-cured or cured. A method in which a coating material for forming an insulating resin layer containing a thermoplastic resin is applied to the adhesive layer 44 side surface of the carrier film 40 and dried. A method of directly laminating a film formed by extrusion molding a composition containing a thermoplastic resin on the adhesive layer 44 side surface of the carrier film 40 . Among the above methods, from the perspective of heat resistance during welding, etc., it is preferred to apply an insulating resin layer forming coating containing a thermosetting resin and an insulating resin layer forming curing agent to the adhesive layer 44 side of the carrier film 40 and semi-cure or cure it. When applying a coating for forming an insulating resin layer containing an epoxy resin as a thermosetting resin and an amine compound as a curing agent for forming the insulating resin layer, the reaction temperature of the epoxy resin and the amine compound is kept moderate, so that the useful life of the coating for forming the insulating resin layer can be sufficiently ensured.

[0061] The coating material for forming the insulating resin layer may contain a solvent as needed. Examples of the solvent include alcohol solvents, ketone solvents, ester solvents, aromatic hydrocarbon solvents, nitrogen atom-containing solvents, etc. The solvent may be used alone or in combination of two or more. Examples of alcoholic solvents include monools having one hydroxyl group and diols having two hydroxyl groups. Examples of monohydric alcohols include isopropyl alcohol, n-butanol, tert-butanol, and allyl alcohol. Examples of dihydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, and butanediols (1,4-butanediol, 1,3-butanediol, 2,3-butanediol, and 1,2-butanediol). Examples of the ether solvent include diethyl ether, dimethyl ether, ethylene glycol, propylene glycol, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, and propylene glycol dialkyl ethers. Examples of the ketone solvent include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, and diacetone alcohol. Examples of the ester solvent include ethyl acetate, propyl acetate, and butyl acetate. Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, ethylbenzene, propylbenzene, and cumene. Examples of the nitrogen atom-containing solvent include N-methylpyrrolidone, dimethylacetamide, and dimethylformamide.

[0062] As a coating method for the above-mentioned coating, for example, a method using various coating machines such as a die coater, a gravure coater, a roll coater, a curtain flow coater, a spin coater, a rod coater, a reverse coater, a kiss coater, a spray coater, a rod coater, an air knife coater, a knife coater, a blade coater, a cast coater, and a screen coater can be applied. When semi-curing or curing the thermosetting resin, heating may be performed using a heater such as a heater or an infrared lamp.

[0063] In step (A1-2), an anchor coating layer-forming paint containing a resin is applied to the surface of the insulating resin layer 10 facing the carrier film 40 to form the anchor coating layer 20. The anchor coating layer-forming paint may contain the same solvent as that contained in the insulating resin layer-forming paint, if necessary. The resin contained in the anchor coating layer-forming paint may be a thermoplastic resin or a thermosetting resin. From the perspective of further improving heat resistance and adhesion, a thermosetting resin is preferably used as the resin contained in the anchor coating layer-forming paint. When a thermosetting resin is used, a curing agent for anchor coating layer formation is added to the anchor coating layer-forming paint. Specifically, in step (A1-2), it is preferred that an anchor coating layer-forming coating material containing a thermosetting resin and a curing agent for anchor coating layer formation is applied onto the insulating resin layer 10 and these are reacted and cured. When the anchor coating layer 20 is formed using a thermosetting resin and a curing agent for forming the anchor coating layer, a general-purpose solvent with a low boiling point (e.g., 75°C to 125°C) such as methyl ethyl ketone or toluene can be used as the solvent contained in the anchor coating layer. This reduces the amount of heat required for drying to remove the solvent, and can suppress thermal degradation of the carrier film 40 and the insulating resin layer 10. Furthermore, when the above-mentioned anchor coating layer-forming paint is applied to the insulating resin layer 10 and cured, the thin anchor coating layer 20 can be closely adhered to the surface of the insulating resin layer 10 with high adhesive force.

[0064] A more preferred method for forming the anchor coating layer 20 uses a polyester resin as the thermosetting resin and a polyisocyanate compound having two or more isocyanate groups as the anchor coating layer curing agent. Isocyanate groups have a low reaction temperature, and after application and drying, the cross-linking reaction of the polyester resin with the polyisocyanate compound proceeds more readily. Urethane bonds are formed by the reaction of the polyester resin's hydroxyl groups with the isocyanate groups of the polyisocyanate compound, further enhancing adhesion to the insulating resin layer 10.

[0065] When a polyisocyanate compound is used as the anchor coat layer-forming curing agent, the molar ratio of the isocyanate groups in the anchor coat layer-forming curing agent to the reactive groups in the thermosetting resin is preferably 1.1 to 20, and more preferably 1.3 to 10. When the thermosetting resin is a polyester resin, the reactive groups in the thermosetting resin are hydroxyl groups, and when the thermosetting resin is an epoxy resin, the reactive groups in the thermosetting resin are epoxy groups. If the ratio of the molar amount of the isocyanate groups of the polyisocyanate compound to the molar amount of the reactive groups of the thermosetting resin is set to a value greater than the lower limit, the isocyanate groups are excessive relative to the reactive groups of the thermosetting resin, resulting in unreacted isocyanate groups. Therefore, the cured product obtained by the reaction of the thermosetting resin and the polyisocyanate compound becomes a cured product having isocyanate groups. The anchor coating 20 containing the above-mentioned cured product can further improve its adhesion to the insulating resin layer 10 due to its isocyanate groups. For example, if the insulating resin layer 10 has a reactive group such as a hydroxyl group that is reactive with isocyanate, the reactive group reacts with the isocyanate group of the anchor coating 20, thereby further improving the adhesion between the insulating resin layer 10 and the anchor coating 20. Examples of reactive groups that are reactive with isocyanate groups include hydroxyl groups, amino groups, amide groups, carboxyl groups, mercapto groups, and epoxy groups. Under the condition that the molar amount of the isocyanate group of the polyisocyanate compound is large relative to the molar amount of the reactive group of the thermosetting resin, the isocyanate groups react with each other, the isocyanate groups react with urethane bonds, etc. to increase the crosslinking density, thereby improving the heat resistance and generating urea bonds with high polarity, etc., which may further improve the adhesion with the metal thin film layer 32. The surface of the insulating resin layer 10 facing the carrier film 40 can be corona treated before applying the anchor coating coating. Corona treatment improves the coating properties of the anchor coating coating and prevents pinholes and uneven film thickness in the anchor coating, thereby ensuring stable anchor coating performance. Furthermore, corona treatment generates reactive groups such as hydroxyl and carboxyl groups on the surface of the insulating resin layer 10 facing the carrier film 40. This reactive group reacts with the anchor coating curing agent, further enhancing adhesion to the insulating resin layer 10.

[0066] In step (A1-3), the metal thin film layer 32 is formed on the surface of the anchor coating layer 20 that faces the insulating resin layer 10 . Examples of methods for forming the metal thin film layer 32 include methods of forming a deposited film by physical vapor deposition, CVD (chemical vapor deposition), methods of forming a plated film by plating, and methods of attaching a metal foil. From the perspective of being able to easily thin the metal thin film layer 32 and to simply form the metal thin film layer 32 using a dry process, methods of forming a deposited film by physical vapor deposition or CVD are more preferred, and methods of forming a deposited film by physical vapor deposition are even more preferred. Among physical vapor deposition methods, vacuum vapor deposition is particularly preferred from the perspective of being applicable to roll-to-roll processing.

[0067] In step (A1-4), a conductive adhesive coating is applied to the surface of the metal thin film layer 32 facing the anchor coating layer 20 to form the anisotropic conductive adhesive layer 34 . The conductive adhesive coating material contains a thermosetting adhesive 34a, conductive particles 34b, and a solvent. The anisotropic conductive adhesive layer 34 is formed by evaporating the solvent from the applied conductive adhesive coating material. Examples of the solvent contained in the conductive adhesive coating include esters (butyl acetate, ethyl acetate, methyl acetate, isopropyl acetate, ethylene glycol monoacetate, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, etc.), and alcohols (methanol, ethanol, isopropyl alcohol, butanol, propylene glycol monomethyl ether, propylene glycol, etc.). The method for applying the conductive adhesive is the same as the method for applying the coating material in step (A1-1). The anisotropic conductive adhesive layer 34 is formed by evaporating the solvent from the applied conductive adhesive coating material.

[0068] In step (A1-5), the release film 50 is laminated on the surface of the anisotropic conductive adhesive layer 34 facing the metal thin film layer 32 so that the release agent layer 54 is in contact with the anisotropic conductive adhesive layer 34 . After laminating the release film 50 on the anisotropic conductive adhesive layer 34, the laminate consisting of the carrier film 40, the insulating resin layer 10, the anchor coating layer 20, the metal thin film layer 32, the anisotropic conductive adhesive layer 34 and the release film 50 can be subjected to a pressurization treatment to improve the adhesion between the layers. The pressure in the pressurization treatment is preferably 0.1 kPa or more and 100 kPa or less, more preferably 0.1 kPa or more and 20 kPa or less, and even more preferably 1 kPa or more and 10 kPa or less. Heating may be performed simultaneously with the pressurization treatment. The heating temperature at this time is preferably 50° C. or higher and 100° C. or lower.

[0069] Specifically, the method (A2) is a method having the following steps (A2-1) to (A2-5). Step (A2-1): a step of forming the insulating resin layer 10 on one surface of the carrier film 40 . Step (A2-2): a step of forming the anchor coating layer 20 on the surface of the insulating resin layer 10 facing the carrier film 40 . Step (A2-3): a step of forming the metal thin film layer 32 on the surface of the anchor coating layer 20 facing the insulating resin layer 10 to form a laminate (p1). Step (A2-4): A step of forming the anisotropic conductive adhesive layer 34 on the release film 50 to form a laminate (p2). Step (A2-5): A step of bonding the laminate (p1) and the laminate (p2) so that the metal thin film layer 32 of the laminate (p1) and the anisotropic conductive adhesive layer 34 of the laminate (p2) are in contact with each other.

[0070] The step (A2-1), the step (A2-2), and the step (A2-3) are the same as the above-mentioned step (A1-1), the step (A1-2), and the step (A1-3), respectively. Step (A2-4) is the same as the above-mentioned step (A1-4) except that a conductive adhesive coating containing a thermosetting adhesive 34a and conductive particles 34b is applied not on the metal thin film layer 32 but on the surface of the release agent layer 54 provided with the release film 50 to form the anisotropic conductive adhesive layer 34. During the lamination of the laminate (p1) and the laminate (p2) in step (A2-5), a pressurization treatment may be performed to improve the adhesion between the laminate (p1) and the laminate (p2). The pressurization conditions are the same as those for the pressurization treatment in step (A1-5). Furthermore, heating may be performed in step (A2-5) in the same manner as in step (A1-5).

[0071] Specifically, the method (A3) includes the following steps (A3-1) to (A3-5). Step (A3-1): a step of forming the insulating resin layer 10 on one surface of the carrier film 40 . Step (A3-2): A step of forming the anchor coating layer 20 on the surface of the insulating resin layer 10 facing the carrier film 40 to form a laminate (p3). Step (A3-3): a step of forming the anisotropic conductive adhesive layer 34 on the release film 50 . Step (A3-4): a step of forming the metal thin film layer 32 on the surface of the anisotropic conductive adhesive layer 34 facing the release film 50 to form a laminate (p4). Step (A3-5): A step of bonding the laminate (p3) and the laminate (p4) so that the anchor coating layer 20 of the laminate (p3) and the metal thin film layer 32 of the laminate (p4) are in contact with each other.

[0072] The steps (A3-1) and (A3-2) are the same as the above-mentioned steps (A1-1) and (A1-2), respectively. Step (A3-3) is the same as the above-mentioned step (A1-4) except that a conductive adhesive coating containing a thermosetting adhesive 34a and conductive particles 34b is formed on the surface of the release agent layer 54 provided with the release film 50 instead of the metal thin film layer 32 to form the anisotropic conductive adhesive layer 34. Step (A3-4) is the same as step (A1-3) above, except that the metal thin film layer 32 is formed not on the anchor coating layer 20 but on the surface of the anisotropic conductive adhesive layer 34 facing the release film 50 . During the lamination of the laminate (p3) and the laminate (p4) in step (A3-5), a pressurization treatment may be applied to improve the adhesion between the laminate (p3) and the laminate (p4). The pressurization conditions are the same as those for the pressurization treatment in step (A1-5). Furthermore, heating may be performed in step (A3-5) in the same manner as in step (A1-5).

[0073] Specifically, the method (A4) includes the following steps (A4-1) to (A4-5). Step (A4-1): A step of forming the insulating resin layer 10 on one surface of the carrier film 40 to form a laminate (a5). Step (A4-2): a step of forming the anisotropic conductive adhesive layer 34 on the release film 50 . Step (A4-3): a step of forming the metal thin film layer 32 on the surface of the anisotropic conductive adhesive layer 34 that faces the release film 50 . Step (A4-4): a step of forming the anchor coating layer 20 on the surface of the metal thin film layer 32 that faces the anisotropic conductive adhesive layer 34 to form a laminate (p6). Step (A4-5): A step of bonding the laminate (p5) and the laminate (p6) so that the insulating resin layer 10 of the laminate (p5) and the anchor coating layer 20 of the laminate (p6) are in contact with each other.

[0074] The step (A4-1) is the same as the above-mentioned step (A1-1). Step (A4-2) is the same as the above-mentioned step (A1-4) except that a conductive adhesive coating containing a thermosetting adhesive 34a and conductive particles 34b is applied not on the metal thin film layer 32 but on the surface of the release agent layer 54 provided with the release film 50 to form the anisotropic conductive adhesive layer 34. The process (A4-3) is the same as the above-mentioned process (A1-3) except that the metal thin film layer 32 is formed not on the anchor coating layer 20 but on the surface of the anisotropic conductive adhesive layer 34 facing the release film 50 . The process (A4-4) is the same as the above-mentioned process (A1-2) except that the anchor coating layer 20 is formed not on the insulating resin layer 10 but on the surface of the metal thin film layer 32 facing the anisotropic conductive adhesive layer 34 . During the lamination of the laminate (p5) and the laminate (p6) in step (A4-5), a pressurization treatment may be applied to improve the adhesion between the laminate (p5) and the laminate (p6). The pressurization conditions are the same as those for the pressurization treatment in step (A1-5). Furthermore, heating may be applied in step (A4-5) in the same manner as in step (A1-5).

[0075] Method (B1), method (B2), method (B3) and method (B4) are the same methods as method (A1), method (A2), method (A3) and method (A4), except that a conductive adhesive coating containing a thermosetting adhesive 36a, conductive particles 36b and a solvent is used to form an isotropic conductive adhesive layer 36 instead of using a conductive adhesive coating containing a thermosetting adhesive 34a, conductive particles 34b and a solvent to form an anisotropic conductive adhesive layer 34.

[0076] The method (C1) comprises the following steps (C1-1) to (C1-4). Step ( C1 - 1 ): a step of forming the insulating resin layer 10 on one surface of the carrier film 40 . Step ( C1-2 ): a step of forming the anchor coating layer 20 on the surface of the insulating resin layer 10 facing the carrier film 40 . Step ( C1-3 ): a step of forming the isotropic conductive adhesive layer 36 on the surface of the anchor coating layer 20 facing the insulating resin layer 10 . Step ( C1-4 ): a step of laminating the release film 50 on the surface of the isotropic conductive adhesive layer 36 facing the insulating resin layer 10 . Method (C1) is the same as method (A1) except that the formation of the metal thin film layer is omitted and an isotropic conductive adhesive is used as the conductive adhesive to form the isotropic conductive adhesive layer 36 directly on the anchor coating layer 20 of the insulating resin layer 10.

[0077] The method (C2) comprises the following steps (C2-1) to (C2-4). Step ( C2 - 1 ): a step of forming the insulating resin layer 10 on one surface of the carrier film 40 . Step (C2-2): a step of forming the anchor coating layer 20 on the surface of the insulating resin layer 10 facing the carrier film 40 to form a laminate (I). Step (C2-3): A step of forming the isotropic conductive adhesive layer 36 on the release film 50 to form a laminate (II). Step (C2-4): A step of bonding the laminate (I) and the laminate (II) so that the anchor coating layer 20 of the laminate (I) and the isotropic conductive adhesive layer 36 of the laminate (II) are in contact with each other. Method (C2) is the same as method (A3) except that the formation of the metal thin film layer is omitted, an isotropic conductive adhesive is used as the conductive adhesive, and the isotropic conductive adhesive layer 36 is bonded to the anchor coating layer 20 .

[0078] The method (C3) comprises the following steps (C3-1) to (C3-4). Step (C3-1): A step of forming the insulating resin layer 10 on one surface of the carrier film 40 to form a laminate (III). Step ( C3 - 2 ): a step of forming the isotropic conductive adhesive layer 36 on the release film 50 . Step (C3-3): a step of forming the anchor coating layer 20 on the surface of the isotropic conductive adhesive layer 36 facing the release film 50 to form a laminate (IV). Step (C3-4): a step of bonding the laminate (III) and the laminate (IV) so that the insulating resin layer 10 of the laminate (III) and the anchor coating layer 20 of the laminate (IV) are in contact with each other. Method (C3) is the same as method (A4) except that the formation of the metal thin film layer is omitted and an isotropic conductive adhesive is used as the conductive adhesive to bond the anchor coating layer 20 to the insulating resin layer 10 .

[0079] Among the above-mentioned production methods, method (A1), method (A2), method (B1), method (B2), or method (C1) is preferred. In these methods, by forming the anchor coating layer on the insulating resin layer, reactive groups in the insulating resin layer can react with the anchor coating layer-forming curing agent. By forming the metal thin film layer directly on the anchor coating layer, the anchor coating layer can more closely follow the surface shape of the metal resin layer, thereby further enhancing the effect of the anchor coating layer.

[0080] (Effect) The electromagnetic wave shielding film 1 of this embodiment includes the anchor coating layer 20 between the insulating resin layer 10 and the metal thin film layer 32 . The anchor coating layer 20 improves the adhesion between the insulating resin layer 10 and the metal thin film layer 32 . In order to improve the heat resistance of the electromagnetic wave shielding film 1, a resin with a high glass transition temperature is sometimes used as the resin constituting the insulating resin layer 10, and sometimes the cross-linking degree of the resin constituting the insulating resin layer 10 is increased. Such an insulating resin layer 10 has a strong cohesive force, and therefore tends to have reduced adhesion to the metal thin film layer 32. However, in this embodiment, the anchor coating 20 is formed in the form of a thin film between the insulating resin layer 10 and the metal thin film layer 32, so that the adhesion between the insulating resin layer 10 and the metal thin film layer 32 can be improved. In addition, in order to improve the heat resistance of the insulating resin layer 10, a functional additive that also improves the heat resistance of the electromagnetic wave shielding film 1 or reduces the adhesion to the metal thin film layer 32 can be added to the insulating resin layer 10.

[0081] (Other embodiments) The electromagnetic wave shielding film of this aspect is not limited to the above-mentioned embodiment. For example, when the adhesive force of the surface of the anisotropic conductive adhesive layer 34 or the isotropic conductive adhesive layer 36 is small, the release film 50 may be omitted. When the insulating resin layer 10 has sufficient flexibility and strength, the carrier film 40 may be omitted. When the carrier film body 42 is a self-adhesive film, the carrier film 40 may not have the adhesive layer 44 . The carrier film 40 may have the adhesive layer 44 replaced with a release agent layer when adhesion to the insulating resin layer can be ensured. The release film 50 may not have the release agent layer 54 when only the release film body 52 has sufficient releasability. The conductive layer may not have a conductive adhesive layer, that is, an anisotropic conductive adhesive layer 34 or an isotropic conductive adhesive layer 36. In the case where the conductive layer does not have a conductive adhesive layer, an anisotropic conductive adhesive or an isotropic conductive adhesive may be applied to an adherend such as the electromagnetic wave shielding film 1 or a printed circuit board to which the electromagnetic wave shielding film is attached, and the electromagnetic wave shielding film 1 and the adherend may be bonded.

[0082] <Printed circuit boards with electromagnetic wave shielding films> One embodiment of the printed wiring board with an electromagnetic wave shielding film of the present invention will be described. The printed circuit board with electromagnetic wave shielding film of this method comprises: a printed circuit board having a printed circuit provided on at least one side of a substrate; an insulating film adjacent to the surface of the printed circuit board on which the printed circuit is provided; and the electromagnetic wave shielding film of the above method, which is provided in such a manner that the conductive layer is adjacent to the insulating film.

[0083] Figure 4 This is a cross-sectional view showing one embodiment of a printed wiring board with an electromagnetic wave shielding film according to this aspect. The printed wiring board 2 with an electromagnetic wave shielding film includes a flexible printed wiring board 60 , an insulating film 70 , and the electromagnetic wave shielding film 1 of the first embodiment. The flexible printed wiring board 60 has a printed circuit 64 provided on at least one surface of a base film 62 . The insulating film 70 is provided on the surface of the flexible printed wiring board 60 on the side where the printed circuit 64 is provided. The anisotropic conductive adhesive layer 34 of the electromagnetic shielding film 1 is bonded to the surface of the insulating film 70 and cured. The anisotropic conductive adhesive layer 34 is electrically connected to the printed circuit 64 via a through hole (not shown) formed in the insulating film 70 . In the printed wiring board 2 with an electromagnetic wave shielding film, the release film is peeled off from the anisotropic conductive adhesive layer 34 .

[0084] When the carrier film 40 is no longer necessary in the printed wiring board 2 with an electromagnetic wave shielding film, the carrier film 40 is peeled off from the insulating resin layer 10 .

[0085] Near the printed circuit 64 (signal circuit, ground circuit, ground layer, etc.) excluding the portion having the through-hole, the metal thin film layer 32 of the electromagnetic shielding film 1 is disposed opposite to each other, separated by the insulating film 70 and the anisotropic conductive adhesive layer 34 . The separation distance between the printed circuit 64 and the metal film layer 32, excluding the portion having the through-holes, is approximately equal to the sum of the thickness of the insulating film 70 and the thickness of the anisotropic conductive adhesive layer 34. The separation distance is preferably greater than 15 μm and less than 200 μm, and more preferably greater than 25 μm and less than 200 μm. If the separation distance is less than 15 μm, the impedance of the signal circuit becomes low. Therefore, in order to achieve a characteristic impedance of 50 Ω, the line width of the signal circuit must be reduced. Deviations in the line width become variations in the characteristic impedance, and reflected resonance noise caused by impedance mismatch easily follows the electrical signal. If the separation distance is greater than 200 μm, the printed wiring board 2 with an electromagnetic wave shielding film becomes thicker and may lack flexibility.

[0086] (Flexible Printed Circuit Board) The flexible printed wiring board 60 is a flexible printed wiring board having a printed circuit 64 formed by processing the copper foil of a copper-clad laminate into a desired pattern by a known etching method. Examples of copper-clad laminates include laminates in which copper foil is attached to one or both sides of a base film 62 via an adhesive layer (not shown); and laminates in which a resin solution for forming the base film 62 is cast on the surface of the copper foil. Examples of the material for the adhesive layer include epoxy resins, polyesters, polyimides, polyamideimides, polyamides, phenolic resins, polyurethane resins, acrylic resins, and melamine resins. The thickness of the adhesive layer is preferably 0.5 μm or more and 30 μm or less.

[0087] [Basement membrane] The base film 62 is preferably a heat-resistant film, more preferably a polyimide film or a liquid crystal polymer film. From the viewpoint of electrical insulation, the surface resistance of the base film 62 is less than 1×10 6 Ω or more. From a practical point of view, the surface resistance of the base film 62 is preferably 1×10 19 Ω or less. The thickness of the base film 62 is preferably 5 μm or more and 200 μm or less, more preferably 6 μm or more and 50 μm or less, and further preferably 10 μm or more and 25 μm or less from the viewpoint of flexibility.

[0088] [Printed Circuit] Examples of the copper foil constituting the printed circuit 64 include rolled copper foil and electrolytic copper foil, and rolled copper foil is preferred from the viewpoint of bendability. The printed circuit 64 can be used as, for example, a signal circuit, a ground circuit, or a ground layer. The thickness of the copper foil is preferably 1 μm or more and 50 μm or less, and more preferably 9 μm or more and 35 μm or less. The ends (terminals) of the printed circuit 64 in the longitudinal direction are not covered by the insulating film 70 or the electromagnetic shielding film 1 and are exposed for soldering connection, connector connection, component mounting, and the like.

[0089] (Insulating film) The insulating film 70 (cover film) is an insulating film in which an adhesive layer (not shown) is formed on one side of an insulating film body (not shown) by applying an adhesive or attaching an adhesive sheet. From the viewpoint of electrical insulation, the surface resistance of the insulating film body is preferably 1×10 6 Ω or more. From a practical point of view, the surface resistance of the insulating film body is preferably 1×10 19 Ω or less. As the insulating film main body, a film having heat resistance is preferable, and a polyimide film or a liquid crystal polymer film is more preferable. The thickness of the insulating film body is preferably 1 μm or more and 100 μm or less, and more preferably 3 μm or more and 25 μm or less from the viewpoint of flexibility. Examples of materials for the adhesive layer include epoxy resins, polyesters, polyimides, polyamideimides, polyamides, phenolic resins, polyurethane resins, acrylic resins, melamine resins, polystyrene, and polyolefins. Epoxy resins may also contain a rubber component (such as carboxyl-modified nitrile rubber) to impart flexibility. The thickness of the adhesive layer is preferably 1 μm or more and 100 μm or less, and more preferably 1.5 μm or more and 60 μm or less.

[0090] The shape of the opening of the through hole formed in the insulating film 70 is not particularly limited. Examples of the shape of the opening of the through hole include a circle, an ellipse, and a square.

[0091] <Method for Manufacturing a Printed Wiring Board with an Electromagnetic Wave Shielding Film> One embodiment of the present invention's method for manufacturing a printed wiring board with an electromagnetic wave shielding film is described. This embodiment of the method comprises crimping a printed wiring board having a printed circuit provided on at least one side of a substrate to the electromagnetic wave shielding film of the aforementioned embodiment through an insulating film. During crimping, the insulating film is brought into close contact with the surface of the printed wiring board on the side having the printed circuit provided thereon, and is also brought into close contact with the conductive adhesive layer of the electromagnetic wave shielding film.

[0092] The printed wiring board 2 with an electromagnetic wave shielding film of the above embodiment can be produced, for example, by a method having the following steps (a) to (d) (see Figure 5 ). Step (a): A step of providing an insulating film 70 having through holes 72 formed therein at positions corresponding to the printed circuit 64 on the surface of the flexible printed wiring board 60 on which the printed circuit 64 is provided, thereby obtaining the printed wiring board 3 with the insulating film. Step (b): After step (a), the printed wiring board 3 with the insulating film and the electromagnetic shielding film 1 from which the release film 50 has been peeled are superimposed so that the anisotropic conductive adhesive layer 34 contacts the surface of the insulating film 70 and pressure-bonded. Step (c): After step (b), a step of peeling off the carrier film 40 when the carrier film 40 is no longer needed. Step (d): A step of mainly curing the anisotropic conductive adhesive layer 34 between the steps (b) and (c), or after the step (c), as necessary. Below, while referring to Figure 5 Each process is explained in detail.

[0093] (Step (a)) Step (a) is a step of laminating insulating film 70 on flexible printed wiring board 60 to obtain printed wiring board 3 with insulating film. Specifically, first, insulating film 70 having through-holes 72 formed therein is overlapped with flexible printed wiring board 60 at positions corresponding to printed circuits 64. Next, an adhesive layer (not shown) of insulating film 70 is bonded to the surface of flexible printed wiring board 60 and the adhesive layer is cured, thereby obtaining printed wiring board 3 with an insulating film. Alternatively, the adhesive layer of insulating film 70 may be temporarily bonded to the surface of flexible printed wiring board 60 and then the adhesive layer is primarily cured in step (d). The adhesion and curing of the adhesive layer are performed by, for example, hot pressing using a press (not shown).

[0094] (Step (b)) Step (b) is a step of pressure-bonding the electromagnetic wave shielding film 1 to the printed wiring board 3 with an insulating film. Specifically, the electromagnetic wave shielding film 1, from which the release film 50 has been removed, is superimposed on the printed wiring board 3 with the insulating film, and then pressure-bonded by heat pressing or the like. This adheres the anisotropic conductive adhesive layer 34 to the surface of the insulating film 70, and the anisotropic conductive adhesive layer 34 is pushed into the through-hole 72, filling the through-hole 72 and electrically connecting it to the printed circuit 64. Thus, the printed wiring board 2 with the electromagnetic wave shielding film is obtained.

[0095] The anisotropic conductive adhesive layer 34 is bonded and cured by, for example, hot pressing using a press (not shown). The hot pressing time is preferably 20 seconds to 60 minutes, more preferably 30 seconds to 30 minutes. If the hot pressing time is at least the lower limit of the above range, the anisotropic conductive adhesive layer 34 can be easily bonded to the surface of the insulating film 70. If the hot pressing time is at most the upper limit of the above range, the manufacturing time of the printed wiring board 2 with an electromagnetic wave shielding film can be shortened.

[0096] The hot pressing temperature (the temperature of the hot plate of the press) is preferably 140°C to 190°C, more preferably 150°C to 180°C. If the hot pressing temperature is at least the lower limit of the above range, the anisotropic conductive adhesive layer 34 can be easily bonded to the surface of the insulating film 70. Furthermore, the hot pressing time can be shortened. If the hot pressing temperature is at most the upper limit of the above range, degradation of the electromagnetic wave shielding film 1, the flexible printed wiring board 60, etc. can be easily suppressed.

[0097] The hot pressing pressure is preferably 0.5 MPa to 20 MPa, more preferably 1 MPa to 16 MPa. If the hot pressing pressure is at least the lower limit of the above range, the anisotropic conductive adhesive layer 34 can be bonded to the surface of the insulating film 70. In addition, the hot pressing time can be shortened. If the hot pressing pressure is at most the upper limit of the above range, damage to the electromagnetic wave shielding film 1, the flexible printed wiring board 60, etc. can be suppressed.

[0098] (Step (c)) Step (c) is a step of peeling the carrier film 40 . Specifically, when the carrier film is no longer necessary, the carrier film 40 is peeled off from the insulating resin layer 10 .

[0099] (Step (d)) Step (d) is a step of mainly curing the anisotropic conductive adhesive layer 34 . When the hot pressing time in step (b) is short, 20 seconds to 10 minutes, it is preferable to perform main curing of the anisotropic conductive adhesive layer 34 between step (b) and step (c) or after step (c). The main curing of the anisotropic conductive adhesive layer 34 is performed using a heating device such as an oven. The heating time is 15 minutes to 120 minutes, more preferably 30 minutes to 60 minutes. When the heating time is equal to or greater than the lower limit of the above range, the anisotropic conductive adhesive layer 34 can be sufficiently cured. When the heating time is equal to or less than the upper limit of the above range, the production time of the printed wiring board 2 with an electromagnetic wave shielding film can be shortened. The heating temperature (atmosphere temperature in the oven) is preferably 120°C to 180°C, more preferably 120°C to 150°C. When the heating temperature is at least the lower limit of the above range, the heating time can be shortened. When the heating temperature is at most the upper limit of the above range, degradation of the electromagnetic wave shielding film 1, the flexible printed wiring board 60, etc. can be suppressed.

[0100] (Effect) The printed wiring board 2 with an electromagnetic wave shielding film of this embodiment uses the above-described electromagnetic wave shielding film 1. Therefore, by using an insulating resin layer having a high glass transition temperature and a high crosslinking density, the heat resistance can be improved while also improving the adhesion between the insulating resin layer 10 and the conductive layer 30. Furthermore, by adding a functional additive that reduces adhesion to the conductive layer 30 to the insulating resin layer 10 to impart further functionality, such as flame retardancy, the adhesion between the insulating resin layer 10 and the conductive layer 30 can also be improved.

[0101] (Other embodiments) The printed wiring board with an electromagnetic wave shielding film of this aspect is not limited to the above-mentioned embodiment. For example, the flexible printed wiring board 60 may include a ground layer on the back side. Furthermore, the flexible printed wiring board 60 may include printed circuits 64 on both sides and have the insulating film 70 and the electromagnetic wave shielding film 1 attached to both sides. Instead of the flexible printed wiring board 60 , a rigid printed circuit board that does not have flexibility may be used. The electromagnetic wave shielding film 1 of the second embodiment or the electromagnetic wave shielding film 1 of the third embodiment may be used instead of the electromagnetic wave shielding film 1 of the first embodiment. [Example]

[0102] (Example 1) 100 g of an epoxy resin (jER828EL, manufactured by Mitsubishi Chemical Corporation), 23 g of N-aminoethylpiperazine as a curing agent, 5 g of carbon black, and 300 g of methyl ethyl ketone were mixed to prepare a coating material for forming an insulating resin layer. The insulating resin layer-forming coating was applied to one surface of a polyethylene terephthalate film (CN100, manufactured by Toyobo Co., Ltd.) serving as a carrier film using a bar coater. The methyl ethyl ketone contained in the applied coating was then volatilized using a dryer. The film was then heated at 80°C for 48 hours to form a 10 μm thick insulating resin layer. The surface of the insulating resin layer opposite the carrier film was coated with an anchor coating coating containing a thermosetting resin, polyisocyanate, solvent, and reaction catalyst as shown in Table 1 using a bar coater. The solvent was then evaporated using a dryer to form an anchor coating. The thickness of the anchor coating is shown in Table 2. A metal thin film layer was formed by vapor-depositing copper by sputtering on the surface of the anchor coating layer facing the insulating resin layer, thereby obtaining an electromagnetic wave shielding film.

[0103]

Table 1

[0104] (Examples 2 to 6, Comparative Examples 1 to 3) An electromagnetic shielding film was obtained in the same manner as in Example 1 except that the anchor coat layer-forming coating material was changed to the coating material shown in Table 1. Table 2 shows the thickness of the anchor coat layer. The anchor coat layer-forming coating materials in Examples 3 to 6 contain a polyisocyanate compound and dibutyltin dilaurate (denoted as "DBTL" in the table) as a reaction catalyst. The solid content of dibutyltin dilaurate relative to 100% by mass of the solid content of the anchor coat layer-forming coating materials is shown in Table 1. The ratio of the molar amount of isocyanate groups in the polyisocyanate to the molar amount of hydroxyl groups in the polyester resin (denoted as "isocyanate group ratio" in the table) is shown in Table 1.

[0105] (Comparative Example 4) An electromagnetic wave shielding film was obtained by directly vapor-depositing copper on the insulating resin layer without forming an anchor coat layer to form a metal thin film layer.

[0106] <Evaluation> The electromagnetic wave shielding film of each example was evaluated for adhesiveness and heat resistance by the following method. The evaluation results are shown in Table 2.

[0107] (Adhesion) A 25 μm thick polyimide film (Kapton 50H, manufactured by DuPont Toray Industries, Inc.) was thermally pressed onto the surface of the metal film layer of the electromagnetic wave shielding film via an adhesive layer. The adhesive layer was a thermosetting layer formed by applying an adhesive coating containing 100 parts by mass of a thermosetting adhesive (epoxy resin, manufactured by DIC Corporation, EXA-4816) and 20 parts by mass of a curing agent (manufactured by Ajinomoto Precision Technology Co., Ltd., PN-23). During the thermal pressing, a hot pressing device (manufactured by Orihara Seisakusho, Ltd., G-12) was used, with the hot plate temperature set to 170°C, the pressure set to 2 MPa, and the pressing time set to 120 seconds. Next, the polyethylene terephthalate film, which was the carrier film of the electromagnetic shielding film to which the polyimide film was thermally pressure-bonded, was peeled off and heated at 150° C. for 1 hour to cure the adhesive layer. Next, a glass plate was attached to the surface of the insulating resin layer opposite the anchor coating using double-sided tape to create a test piece. Using a tensile tester (Autograph, manufactured by Shimadzu Corporation), the polyimide film in the test piece was peeled off at 180° to measure the peel force. The greater the peel force, the higher the adhesion between the insulating resin layer and the anchor coating layer through the metal thin film layer.

[0108] (Heat resistance) A copper-clad laminate composed of copper foil and polyimide film was thermally pressed onto the surface of the metal film layer of the electromagnetic wave shielding film via an adhesive layer. The adhesive layer was a thermosetting layer formed by applying an adhesive coating containing 100 parts by mass of a thermosetting adhesive (epoxy resin, manufactured by DIC Corporation, EXA-4816) and 20 parts by mass of a curing agent (manufactured by Ajinomoto Precision Technology Co., Ltd., PN-23). During the thermal pressing, a hot press apparatus (manufactured by Orihara Seisakusho, G-12) was used, with a hot plate temperature of 170°C, a pressure of 2 MPa, and a pressing time of 120 seconds. Next, the polyethylene terephthalate film serving as the carrier film was peeled off, and the adhesive layer was cured by heating at 150° C. for 1 hour. Next, the electromagnetic shielding film, to which the copper-clad laminate was thermally press-bonded, was floated in a 288°C solder bath, with solder in contact with the surface of the insulating resin layer opposite the anchor coating layer. After 10 seconds, the film was lifted out. This operation was repeated three times, and the insulating resin layer was visually inspected for heat resistance, which was evaluated according to the following criteria. A: No changes were observed in the insulating resin layer, indicating no problem. B: Fine wrinkles are seen on the surface of the insulating resin layer. C: Abnormalities such as bubbles forming in the insulating resin layer are observed.

[0109]

Table 2

[0110] Each of the Examples containing a resin having a glass transition temperature of 40° C. or higher and 105° C. or lower and having an anchor coating layer having a thickness of 1 nm or higher and 500 nm or lower was excellent in adhesiveness and heat resistance. Comparative Example 1, which contains a resin having a glass transition temperature of 40° C. to 105° C. but has an anchor coating layer having a thickness exceeding 1000 nm, has low adhesiveness and low heat resistance. Comparative Example 2 having an anchor coating layer containing a resin having a glass transition temperature of less than 40° C. has an anchor coating layer thickness of 1 nm to 500 nm, but has low adhesiveness and slightly low heat resistance. The anchor coating layer of Comparative Example 3 having an anchor coating layer containing a resin having a glass transition temperature exceeding 105° C. had a thickness of 1 nm to 500 nm, but had low adhesiveness. Comparative Example 4 having no anchor coating layer had low adhesiveness. Explanation of symbols

[0111] 1Electromagnetic wave shielding film 2Printed circuit boards with electromagnetic wave shielding films 3 Printed circuit board with insulating film 10 Insulating resin layer 20 Anchor coating 30 conductive layer 32 Metal film layer 34 Anisotropic conductive adhesive layer 34a Heat-curing adhesive 34b Conductive particles 36 Isotropic conductive adhesive layer 36a Thermosetting adhesive 36b Conductive particles 40 Carrier Film 42 Carrier membrane body 44 adhesive layer 50 release film 52 Release film body 54 release agent layer 60 Flexible Printed Circuit Board 62 basement membrane 64 printed circuits 70 Insulation film 72 through holes.

Claims

1. An electromagnetic wave shielding film, characterized in that An insulating resin layer, a conductive layer, and an anchor coating layer formed between the insulating resin layer and the conductive layer. The anchor coating layer has a thickness of 50 nm to 500 nm, is a cured product of a thermosetting resin formed by reacting a thermosetting resin with a curing agent for forming the anchor coating layer, and contains a resin having a glass transition temperature of 40° C. to 105° C. The resin contained in the anchor coating is a single polyester resin.

2. The electromagnetic wave shielding film according to claim 1, wherein The resin contained in the anchor coating layer has a urethane bond.

3. The electromagnetic wave shielding film according to claim 1 or 2, wherein The insulating resin contained in the insulating resin layer has at least one of a hydroxyl group, an amino group, an amide group, a carboxyl group, a mercapto group, and an epoxy group.

4. The electromagnetic wave shielding film according to any one of claims 1 to 3, wherein The conductive layer includes a metal thin film layer, and the metal thin film layer is in contact with the anchor coating layer. The electromagnetic wave shielding film according to claim 4 , wherein The conductive layer further includes a conductive adhesive layer on a surface of the metal thin film layer opposite to the anchor coating layer. 6 . The electromagnetic wave shielding film according to claim 1 , wherein The insulating resin layer further has a carrier film on the side opposite to the anchor coating layer.

7. A printed circuit board with an electromagnetic wave shielding film, characterized in that: have: A printed circuit board having a printed circuit provided on at least one side of a substrate; an insulating film adjacent to a surface of the printed wiring board on a side where the printed circuit is provided; as well as The electromagnetic wave shielding film according to any one of claims 1 to 6, wherein the conductive layer is provided adjacent to the insulating film.

8. A method for manufacturing an electromagnetic wave shielding film, characterized in that: The process includes the following steps: A step of applying a coating material for forming an insulating resin layer containing a thermosetting resin and a curing agent for forming an insulating resin layer to the adhesive layer side of the carrier film and semi-curing the coating material. forming an anchor coating layer having a thickness of 50 nm to 500 nm, which contains a resin having a glass transition temperature of 40° C. to 105° C., on the surface of the semi-cured insulating resin layer opposite to the carrier film; forming a metal thin film layer on the surface of the anchor coating layer opposite to the insulating resin layer; a step of applying a conductive adhesive coating to the surface of the metal thin film layer opposite to the anchor coating layer to form an anisotropic conductive adhesive layer; and a step of laminating a release film on the surface of the anisotropic conductive adhesive layer opposite to the metal thin film layer, After laminating the release film on the anisotropic conductive adhesive layer, the laminate consisting of the carrier film, insulating resin layer, anchor coating layer, metal thin film layer, anisotropic conductive adhesive layer and release film is subjected to a pressurization treatment for improving the adhesion between the layers.

9. The method for producing an electromagnetic wave shielding film according to claim 8, wherein: When forming the anchor coating layer, a thermosetting resin is reacted with a curing agent for forming the anchor coating layer.

10. The method for producing an electromagnetic wave shielding film according to claim 8 or 9, wherein: The anchor coating layer-forming curing agent is a compound having two or more isocyanate groups.

11. The method for producing an electromagnetic wave shielding film according to claim 10, wherein: The molar ratio of the amount of isocyanate groups in the anchor coating layer-forming curing agent to the amount of reactive groups in the thermosetting resin is 1.1 or more and 20 or less.

12. The method for producing an electromagnetic wave shielding film according to claim 9, wherein: The metal thin film layer is formed by vacuum evaporation.

13. The method for producing an electromagnetic shielding film according to any one of claims 8 to 12, wherein: When forming the insulating resin layer, the epoxy resin is reacted with a curing agent for forming the insulating resin layer.

14. The method for producing an electromagnetic wave shielding film according to claim 13, wherein: The insulating resin layer-forming curing agent is an amine compound.

15. The method for producing an electromagnetic wave shielding film according to claim 14, wherein: The amine compound is an aliphatic amine compound.

16. A method for manufacturing a printed circuit board with an electromagnetic wave shielding film, characterized in that: A printed wiring board having a printed circuit provided on at least one surface of a substrate and the electromagnetic wave shielding film according to any one of claims 1 to 6 are pressure-bonded via an insulating film. During the pressure bonding, the conductive layer of the electromagnetic wave shielding film and the insulating film are brought into close contact with each other.

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