CN110809394A

CN110809394A - Electromagnetic wave shielding film and method for manufacturing same, and printed wiring board with electromagnetic wave shielding film and method for manufacturing same

Info

Publication number: CN110809394A
Application number: CN201910624218.7A
Authority: CN
Inventors: 吉田一义; 权田贵司
Original assignee: Shin Etsu Polymer Co Ltd
Current assignee: Shin Etsu Polymer Co Ltd
Priority date: 2018-08-06
Filing date: 2019-07-11
Publication date: 2020-02-18
Anticipated expiration: 2039-07-11
Also published as: JP2020024977A; CN110809394B

Abstract

The present invention relates to an electromagnetic wave shielding film and a method for manufacturing the same, and a printed wiring board with an electromagnetic wave shielding film and a method for manufacturing the same. Provided are an electromagnetic wave shielding film and a method for manufacturing the same, wherein the adhesion between an insulating resin layer and a conductive layer is sufficiently improved. The electromagnetic wave shielding film (1) comprises an insulating resin layer (10) and a metal-containing conductive layer (20) adjacent to the insulating resin layer (10), wherein the insulating resin layer (10) contains an aromatic polyether ketone and a polyether imide. The aromatic polyether ketone may be polyether ether ketone or polyether ketone. The polyetherimide may have a glass transition temperature of 200 ℃ or higher and a repeating unit represented by a specific chemical formula.

Description

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

Technical Field

The present invention relates to an electromagnetic wave shielding film and a method for manufacturing the same, and a printed wiring board with an electromagnetic wave shielding film and a method for manufacturing the same.

Background

In order to shield electromagnetic noise generated from a printed wiring board and electromagnetic noise from the outside, an electromagnetic wave shielding Film including an insulating resin layer and a conductive layer adjacent to the insulating resin layer may be provided on a surface of the printed wiring board with an insulating Film (cover Film) interposed therebetween (see, for example, patent document 1).

The electromagnetic wave shielding film is produced, for example, as follows: the carrier film is produced by applying a coating material containing a thermosetting resin, a curing agent and a solvent to one surface of a carrier film, drying the coating material to form an insulating resin layer, and providing a conductive layer on the surface of the insulating resin layer. The conductive layer is formed of at least one of a metal thin film layer and an adhesive layer (e.g., a conductive adhesive layer).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-86120

Disclosure of Invention

Technical problem to be solved by the invention

Conventional insulating resin layers made of thermosetting resins have low adhesion to conductive layers made of metals. In particular, when the conductive layer has a metal thin film layer and the metal thin film layer is in contact with the insulating resin layer, the adhesiveness is particularly low. Therefore, in the conventional electromagnetic wave shielding film, the adhesion between the insulating resin layer and the conductive layer is weak, and delamination may occur during handling of the electromagnetic wave shielding film. For example, when the carrier film is peeled from the insulating resin layer, the insulating resin layer is sometimes peeled from the conductive layer together with the carrier film.

The present invention aims to provide an electromagnetic wave shielding film and a manufacturing method thereof, wherein the adhesion between a conductive layer containing metal and an insulating resin layer can be sufficiently improved.

Means for solving the problems

The present invention includes the following aspects.

[1] An electromagnetic wave shielding film comprising an insulating resin layer and a metal-containing conductive layer adjacent to the insulating resin layer, wherein the insulating resin layer contains an aromatic polyether ketone and a polyether imide.

[2] The electromagnetic wave shielding film according to [1], wherein the aromatic polyether ketone is polyether ether ketone or polyether ketone.

[3] The electromagnetic wave shielding film according to [1] or [2], wherein the polyetherimide has a glass transition temperature of 200 ℃ or higher and has a repeating unit represented by the following chemical formula (A);

[ solution 1]

[4] The electromagnetic wave-shielding film according to any one of [1] to [3], wherein the aromatic polyether ketone is contained in an amount of 5 mass% or more and 95 mass% or less, and the polyether imide is contained in an amount of 5 mass% or more and 95 mass% or less, with respect to the total mass of the insulating resin layers.

[5] The electromagnetic wave shielding film according to any one of [1] to [4], wherein the thickness of the insulating resin layer is 2 μm or more and 10 μm or less.

[6] The electromagnetic wave shielding film according to any one of [1] to [5], wherein the conductive layer is a metal deposition layer.

[7] The electromagnetic wave-shielding film according to [6], wherein the metal deposition layer is a silver deposition layer or a copper deposition layer.

[8] The electromagnetic wave shielding film according to any one of [1] to [7], further comprising a carrier film on a surface of the insulating resin layer opposite to the conductive layer.

[9] A printed wiring board with an electromagnetic wave shielding film, comprising: a printed wiring board having a printed circuit provided on at least one surface 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], which is provided so that the conductive layer is adjacent to the insulating film.

[10] A method for manufacturing an electromagnetic wave shielding film, comprising the steps of: a mixed resin of aromatic polyether ketone and polyether imide is molded into a film shape to form an insulating resin layer, and a conductive layer is formed on one side of the insulating resin layer.

[11] A method for manufacturing a printed wiring board with an electromagnetic wave shielding film, comprising the steps of: a printed wiring board having a printed circuit on at least one surface of a substrate and the electromagnetic wave shielding film according to any one of [1] to [8] are pressure-bonded through an insulating film.

ADVANTAGEOUS EFFECTS OF INVENTION

The electromagnetic wave shielding film of the present invention can sufficiently improve the adhesion between the conductive layer containing a metal and the insulating resin layer.

According to the method for manufacturing an electromagnetic wave shielding film of the present invention, the electromagnetic wave shielding film can be easily manufactured.

In the electromagnetic wave shielding film-equipped printed wiring board of the present invention, the adhesion between the metal-containing conductive layer and the insulating resin layer is sufficiently high.

According to the method for manufacturing a printed wiring board with an electromagnetic wave shielding film of the present invention, the above-described printed wiring board with an electromagnetic wave shielding film can be easily manufactured.

Drawings

Fig. 1 is a cross-sectional view showing a first embodiment of an electromagnetic wave-shielding film of the present invention.

Fig. 2 is a cross-sectional view showing a second embodiment of the electromagnetic wave-shielding film of the present invention.

Fig. 3 is a cross-sectional view showing a third embodiment of the electromagnetic wave-shielding film of the present invention.

Fig. 4 is a cross-sectional view showing one embodiment of the printed wiring board with an electromagnetic wave shielding film of the present invention.

Fig. 5 is a cross-sectional view showing a manufacturing process of the printed wiring board with the electromagnetic wave shielding film of fig. 4.

Detailed Description

The following definitions of terms apply to the full scope of the 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 having conductivity in the thickness direction and not having conductivity in the surface direction.

The phrase "a conductive adhesive layer having no conductivity in the in-plane direction" means that the surface resistance is 1X 10⁴And a conductive adhesive layer having an omega or higher.

The average particle diameter of the particles is a value obtained as follows: the average particle size of the particles was obtained by randomly selecting 30 particles from a microscopic image of the particles, measuring the minimum diameter and the maximum diameter of each particle, and arithmetically averaging the measured particle sizes of the 30 particles with the median value of the minimum diameter and the maximum diameter as the particle size of one particle. The same applies to the average particle diameter of the conductive particles.

The cross section of the object to be measured was observed with a microscope, and the thickness at 5 points was measured and averaged to obtain the thickness of the film (release film, insulating film, etc.), coating film (insulating resin layer, conductive adhesive layer, etc.), metal thin film layer, etc.

The storage modulus is calculated from the stress applied to the object to be measured and the detected strain, and is measured as one of the viscoelastic characteristics using a dynamic viscoelasticity measuring apparatus that outputs as a function of temperature or time.

The tensile modulus was determined by measurement using a tensile tester in accordance with JIS K7127. The value obtained by dividing the tensile stress applied to the object of measurement by the strain generated in the object of measurement within the elastic limit is the same as the young's modulus.

The 10% compressive strength of the conductive particles was determined from the measurement results using a micro compression tester by the following formula (α).

C(x)＝2.48P/πd²(α)

Wherein C (x) is 10% compressive strength (MPa), P is a test force (N) at 10% displacement of the particle diameter, and d is the particle diameter (mm).

Surface resistance refers to the resistance measured as follows: using two thin-film metal electrodes (length 10mm, width 5mm, inter-electrode distance 10mm) formed by vapor plating gold on quartz glass, the object to be measured was placed on the electrodes, a region of 10mm × 20mm of the object to be measured was pressed with a load of 0.049N from above the object to be measured, and the resistance between the electrodes was measured at a measurement current of 1mA or less.

For convenience of explanation, the size ratio in fig. 1 to 5 is different from the actual size ratio.

< electromagnetic wave shielding film >

A first aspect of the present invention is an electromagnetic wave shielding film including an insulating resin layer and a metal-containing conductive layer adjacent to the insulating resin layer, the insulating resin layer containing an aromatic polyether ketone and a polyether imide.

Fig. 1 is a sectional view showing an electromagnetic wave shielding film 1 of a first embodiment, fig. 2 is a sectional view showing an electromagnetic wave shielding film 1 of a second embodiment, and fig. 3 is a sectional view showing an electromagnetic wave shielding film 1 of a third embodiment.

The electromagnetic wave shielding films 1 of the first, second, and third embodiments each have an insulating resin layer 10, a conductive layer 20 adjacent to the insulating resin layer 10, a carrier film 30 adjacent to the insulating resin layer 10 on the side opposite to the conductive layer 20, and a release film 40 adjacent to the conductive layer 20 on the side opposite to the insulating resin layer 10.

In the electromagnetic wave shielding film 1 of the first embodiment, the conductive layer 20 includes the metal thin film layer 22 adjacent to the insulating resin layer 10 and the anisotropic conductive adhesive layer 24 adjacent to the release film 40.

In the electromagnetic wave shielding film 1 of the second embodiment, the conductive layer 20 includes the metal thin film layer 22 adjacent to the insulating resin layer 10 and the isotropic conductive adhesive layer 26 adjacent to the release film 40.

In the electromagnetic wave shielding film 1 of the third embodiment, the conductive layer 20 includes the isotropic conductive adhesive layer 26.

(insulating resin layer)

After the electromagnetic wave shielding film 1 is bonded to the surface of the insulating film provided on the surface of the flexible printed wiring board and the carrier film 30 is peeled off, the insulating resin layer 10 serves as a protective layer of the conductive layer 20.

The insulating resin layer 10 contains aromatic polyether ketone and polyether imide.

The aromatic polyether ketone is a polymer having a structure in which benzene rings are bonded to each other via an ether bond and a structure in which benzene rings are bonded to each other via a ketone group.

The polyether imide is a polymer having a structure in which aromatic rings are bonded to each other via an ether bond and a structure in which aromatic rings are bonded to each other via an imide bond.

Examples of the aromatic polyether ketone include: polyether ether ketone (PEEK) having a chemical structure shown in chemical formula (1), polyether ketone (PEK) having a chemical structure shown in chemical formula (2), polyether ketone (PEKK) having a chemical structure shown in chemical formula (3), polyether ether ketone (PEEKK) having a chemical structure shown in chemical formula (4), and polyether ketone ether ketone (PEKEKK) having a chemical structure shown in chemical formula (5). The aromatic polyether ketone contained in the insulating resin layer 10 may be one kind alone, or two or more kinds.

The aromatic polyether ketone may have 2 or more chemical structures among the chemical structures represented by the chemical formulas (1) to (5).

The aromatic polyether ketone represented by chemical formulas (1) to (5) has hydrogen atoms at both ends.

[ solution 2]

Among the aromatic polyether ketones, PEEK is preferable in terms of easy formation of the insulating resin layer 10 and further improvement of adhesion to the metal film layer 22.

From the viewpoint of mechanical properties, n in each of the chemical formulas (1) to (5) is preferably 10 or more, and more preferably 20 or more. On the other hand, n is preferably 5000 or less, more preferably 1000 or less, from the viewpoint that an aromatic polyether ketone can be easily produced. That is, it is preferably 10 or more and 5000 or less, and more preferably 20 or more and 1000 or less.

The aromatic polyether ketone may be a block copolymer, a random copolymer or a modified product of the aromatic polyether ketone and another copolymerizable monomer such as ether sulfone, within a range not to impair the effects of the present invention.

In the aromatic polyether ketone, the proportion of the polyether ketone repeating unit represented by any one of the chemical formulas (1) to (5) is 50 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, still more preferably 80 mol% or more and 100 mol% or less, and most preferably 100 mol% with respect to 100 mol% of the aromatic polyether ketone. In the aromatic polyether ketone, if the ratio of the repeating units of the aromatic polyether ketone is equal to or higher than the lower limit value, the adhesion between the insulating resin layer 10 and the conductive layer 20 can be further enhanced.

Methods for producing aromatic polyether ketones are disclosed in, for example, Japanese patent laid-open Nos. 50-27897, 51-119797, 52-38000, 54-90296, 55-23574 and 56-2091.

Examples of commercially available PEEK products include: victrex Peek series (product name) manufactured by Victrex corporation, Vestakeep series (product name) manufactured by Daicel Evonik corporation, and Ketasspray polyether ether ketone series (product name) manufactured by Solvay Specialty Polymers.

As the Polyetherimide (PEI) constituting the insulating resin layer 10, for example, PEI having a glass transition temperature of 200 ℃. As PEI having a glass transition temperature of 200 ℃ or higher, PEI having a repeating unit represented by the following formula (A) can be mentioned, for example.

[ solution 3]

To PEI having a repeating unit represented by the following chemical formula (B) may be added within a range not impairing the effects of the present invention.

[ solution 4]

Specific examples of PEI having a repeating unit of the above formula (A) include ULTEM 1010-NB and ULTEM 9011-NB [ all of the products of SABIC INVAVATIVE PLASTTICS, Inc. ]. Examples of a method for producing PEI having a repeating unit of the above chemical formula (a) include a known method of polycondensing 4,4' -isopropylidenebis (p-phenyleneoxy) diphthalic anhydride with m-phenylenediamine.

Specific examples of PEI having a repeating unit of the above formula (B) include ULTEM CRS5001-1000-NB (trade name manufactured by SABIC INNOVATIVE PLASTIC CORPORATION). Examples of a method for producing PEI having a repeating unit of the above chemical formula (B) include a known method of polycondensing 4,4' -isopropylidenebis (p-phenyleneoxy) diphthalic acid and p-phenylenediamine.

The polyether imide constituting the insulating resin layer 10 may be a block copolymer, a random copolymer, or a modified product of the polyether imide and another copolymerizable monomer such as an amide group, an ester group, a sulfonyl group, or a siloxane group. Examples thereof include ULTEM XH6050-1000 (product name of SABIC INVAVATIVE PLASTICS Co.) having a glass transition temperature of 238 ℃ as a polyetherimide sulfone copolymer, and ULTEM STM1700-1000 (product name of SABIC INVAVATIVE PLASTICS Co.) as a polyetherimide/siloxane copolymer.

Since PEI having the repeating unit of the chemical formula (a) has very excellent compatibility with PEEK having the repeating unit of the chemical formula (1), it is preferable that the insulating resin layer 10 is formed of a mixed resin in which these are combined.

Among the resin components constituting the insulating resin layer 10, PEEK having a repeating unit represented by the above chemical formula (1) and PEI having a repeating unit represented by the above chemical formula (a) and having a glass transition temperature of 200 ℃ or higher are preferable: the polyether ether ketone (PEEK) is 5-95 mass% in terms of composition mass ratio, and the polyether imide resin is 5-95 mass%. Here, more preferably, PEEK is 10 mass% or more and 90 mass% or less, and the polyetherimide resin is 10 mass% or more and 90 mass% or less, and still more preferably, PEEK is 20 mass% or more and 80 mass% or less, and the polyetherimide resin is 20 mass% or more and 80 mass% or less.

When the lower limit of the above range is not less than the upper limit, the heat resistance is further excellent, and when the upper limit of the above range is not more than the lower limit, the adhesiveness of the insulating resin layer 10 to the conductive layer 20 is further excellent.

The glass transition temperature (glass transition temperature: Tg) of the resin constituting the insulating resin layer 10 is changed depending on the mixing ratio of the PEEK and the PEI. The higher the proportion of PEI to PEEK, the higher the Tg of the insulating resin layer 10 tends to be. It is preferable that the resin has a high Tg because the resin is less susceptible to heat treatment in the production of an electromagnetic wave shielding film and to a high-temperature environment in use. The Tg of the resin is preferably 140 to 210 ℃, more preferably 165 to 205 ℃, and still more preferably 170 to 200 ℃. When the lower limit value is not less than the above range, wrinkles, ripples, local melting, etc. on the surface of the insulating resin layer 10 due to heat treatment in the production of the electromagnetic wave shielding film can be prevented. When the upper limit value of the above range is less than or equal to the upper limit value, the adhesiveness to the metal thin film 22 can be further improved.

Examples of the method of forming the insulating resin layer 10 from a mixed resin of aromatic polyether ketone and PEI include the following methods: the molding material is prepared by melt-kneading an aromatic polyether ketone and PEI by an extrusion molding machine, and the insulating resin layer is continuously extruded from the molding material. The following description will be made of the case where the aromatic polyether ketone is PEEK, but the same can be made in the case of an aromatic polyether ketone other than PEEK.

Examples of the method for producing PEEK and PEI include the following methods: (a) respectively stirring and mixing PEEK and PEI particles at the temperature of 0-50 ℃, and then melting and mixing to prepare a molding material; (b) adding PEI to molten PEEK, and melt-kneading these to prepare a molding material; alternatively, PEEK is added to molten PEI, and these are melt-kneaded to prepare a molding material. From the viewpoint of improving dispersibility, the method (a) is preferred.

The production method of the above (a) will be further explained. For stirring and mixing of PEEK and PEI, a tumbler mixer, henschel mixer, V-type mixer, Nauta (Nauta) mixer, ribbon mixer, universal stirring mixer, or the like is used. The stirred mixture can be dispersed with PEEK and PEI by melting and kneading the mixture with a melt kneader including a mixing roll, a pressure kneader, a single-screw extrusion molding machine, a twin-screw extrusion molding machine, a three-screw extrusion molding machine, a four-screw extrusion molding machine, an eight-screw extrusion molding machine, and the like.

The temperature for melt-kneading PEEK and PEI may be equal to or higher than the melting point of PEEK or equal to or higher than the glass transition temperature of PEI but equal to or lower than 450 ℃, and preferably equal to or higher than 350 ℃ but equal to or lower than 430 ℃. When the melt kneading temperature is not lower than the lower limit of the above range, PEEK and PEI can be dispersed more uniformly. When the upper limit value of the above range is less than or equal to the upper limit value, decomposition of PEEK or PEI due to heat can be suppressed.

The production method of the above (b) will be further described. Either PEEK or PEI can be dispersed by melting with a melting and kneading machine including a mixing roll, a pressure kneader, a single-screw extrusion molding machine, a two-screw extrusion molding machine, a three-screw extrusion molding machine, a four-screw extrusion molding machine, an eight-screw extrusion molding machine, and the like, and then adding another unmelted resin to melt and knead. The temperature for the melt kneading is preferably in the same temperature range as in the above (a).

The insulating resin layer 10 can be formed by a known molding method such as a melt extrusion molding method, a calendar molding method, or a casting method using a mixed resin composed of a mixed resin of PEEK and PEI.

The insulating resin layer 10 may contain other resins in addition to the aromatic polyether ketone and PEI. Examples of the other resin include Polyimide (PI), polyamide imide (PAI), polyamide 6T (PA6T), modified polyamide 6T (modified PA6T), polyamide 9T (PA9T), polyamide 10T (PA10T), polyamide 11T (PA11T), polyamide 6(PA6), polyamide 66(PA66), polyamide 46(PA46), Polysulfone (PSU), Polyethersulfone (PES), polyphenylsulfone (PPSU), polyphenylenesulfide (PPS), polyphenylenesulfide ketone, polyphenylenesulfide sulfone, and Liquid Crystal Polymer (LCP).

The content of the aromatic polyether ketone is preferably 5 mass% or more and 95 mass% or less and the content of the PEI is preferably 5 mass% or more and 95 mass% or less with respect to the total mass of the insulating resin layer 10. More preferably, the content of the aromatic polyether ketone is 10 mass% or more and 90 mass% or less, and the content of the PEI is 10 mass% or more and 90 mass% or less.

It is preferable that the insulating resin layer 10 have a high tensile modulus at 160 ℃ because the insulating resin layer is less susceptible to heat treatment in the production of an electromagnetic wave shielding film or a high-temperature environment in use. The tensile modulus is preferably 1000N/mm²～5000N/mm²More preferably 1500N/mm²～4000N/mm²More preferably 2000N/mm²～3000N/mm². When the lower limit value of the above range or more, generation of wrinkles, waviness, local breakage, and the like in the insulating resin layer 10 due to heat treatment at the time of manufacturing the electromagnetic wave shielding film can be prevented. When the value is equal to or less than the upper limit of the above range, the balance between the tensile modulus of the film and the tensile modulus of the other layer is more favorable, and the adhesiveness to the metal thin film 22 can be further improved.

The insulating resin layer 10 may contain either or both of a colorant (pigment, dye, etc.) and a filler in order to conceal the printed circuit of the printed wiring board or to impart designability to the printed wiring board with an electromagnetic wave shielding film.

Either or both of the colorant and the filler are preferably a pigment or a filler in view of weather resistance, heat resistance and concealing properties, and more preferably a black pigment or a combination of a black pigment and another pigment or a filler in view of concealing properties and designing properties of a printed circuit.

The insulating resin layer 10 may contain additives such as an antioxidant, a light stabilizer, an ultraviolet stabilizer, a plasticizer, a lubricant, a flame retardant, an antistatic agent, a heat resistance improver, an inorganic filler, an organic filler, and the like, within a range not to impair the characteristics of the present invention.

The surface resistance of the insulating resin layer 10 is preferably 1 × 10 in view of electrical insulation⁶Omega or more. From the practical viewpoint, the surface resistance of the insulating resin layer 10 is preferably 1 × 10¹⁹Omega is less than or equal to.

The thickness of the insulating resin layer 10 is preferably 2.0 μm or more and 30 μm or less, and more preferably 3.0 μm or more and 10 μm or less. If the thickness of the insulating resin layer 10 is not less than the lower limit of the above range, the insulating resin layer 10 can sufficiently function as a protective layer. If the thickness of the insulating resin layer 10 is not more than the upper limit of the above range, the electromagnetic wave-shielding film 1 can be made thin.

(conductive layer)

The conductive layer has at least a conductive adhesive layer containing a metal. The metal may be in the form of a film, a particle, or other shapes.

Specifically, as described above, the conductive layer 20 in the first embodiment includes the metal thin film layer 22 adjacent to the insulating resin layer 10 and the anisotropic conductive adhesive layer 24 adjacent to the release film 40.

The conductive layer 20 in the second embodiment has a metal thin film layer 22 adjacent to the insulating resin layer 10 and an isotropic conductive adhesive layer 26 adjacent to the release film 40.

The conductive layer 20 in the third embodiment includes an isotropic conductive adhesive layer 26.

The conductive layer 20 preferably includes a metal thin film layer 22, an anisotropic conductive adhesive layer 24, and an isotropic conductive adhesive layer 26, in view of sufficiently high electromagnetic wave shielding properties. That is, the conductive layer 20 preferably has two layers, i.e., a metal thin film layer and a conductive adhesive layer.

[ Metal thin film layer ]

The metal thin-film layer 22 is a layer of a thin film containing a metal. The metal thin film layer 22 is formed so as to spread out in the planar direction, and therefore has conductivity in the planar direction, and functions as an electromagnetic wave shielding layer or the like.

Examples of the metal thin film layer 22 include: a vapor deposition film formed by physical vapor deposition (vacuum vapor deposition, sputtering, ion beam vapor deposition, electron beam vapor deposition, or the like) or chemical vapor deposition, a plating film formed by plating, a metal foil, or the like. The conductive layer 20 is preferably a vapor deposited film or a plated film in terms of excellent conductivity in the plane direction. The conductive layer 20 is preferably a vapor deposited film, and more preferably a vapor deposited film formed by physical vapor deposition, because the conductive layer 20 can be made thin, has excellent conductivity in the direction of a small thickness surface, and can be easily formed by a dry process.

Examples of the metal constituting the metal thin film layer 22 include: aluminum, silver, copper, gold, conductive ceramics, and the like, and silver or copper is preferable from the viewpoint of electrical conductivity.

The metal thin film layer 22 is preferably a metal deposition layer, and more preferably a silver deposition layer or a copper deposition layer, in terms of high electromagnetic wave shielding properties and ease of formation of the metal thin film layer.

The surface resistance of the metal thin film layer 22 is preferably 0.001 Ω to 1 Ω, and more preferably 0.001 Ω to 0.5 Ω. If the surface resistance of the metal thin film layer 22 is not less than the lower limit of the above range, the metal thin film layer 22 can be sufficiently reduced in thickness. If the surface resistance of the metal thin film layer 22 is not more than the upper limit value of the above range, the electromagnetic wave shielding layer can sufficiently function.

The thickness of the metal thin film layer 22 is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.05 μm or more and 3 μm or less. If the thickness of the metal thin film layer 22 is 0.01 μm or more, the electrical conductivity in the in-plane direction is further improved. If the thickness of the metal thin film layer 22 is 0.05 μm or more, the electromagnetic noise shielding effect is further improved. If the thickness of the metal thin film layer 22 is not more than the upper limit of the above range, the electromagnetic wave-shielding film 1 can be made thin. In addition, the electromagnetic wave shielding film 1 is excellent in productivity and flexibility.

[ blackened layer ]

The metal thin film layer 22 such as the silver deposition layer and the copper deposition layer has high light reflectivity and metallic luster. In order to suppress the metallic luster, the conductive layer 20 may have a blackened layer on the surface of the metal thin film layer 22 on the insulating resin layer 10 side. For example, when the electromagnetic wave shielding film 1 is used for a flexible printed wiring board for a display, a blackening layer is preferably provided between the metal thin film layer 22 and the insulating resin layer 10 in order to prevent gloss of the metal thin film layer 22 from affecting visibility of the display.

The black layer is a black layer made of a light absorbing material and having light-blocking properties. Specifically, the blackening layer is preferably made to have a luminance L as defined in JIS Z8781-5^＊Is 5 or less. Having a brightness L^＊The smaller the value of (b), the larger the blackness, and the more the light reflection can be suppressed.

The black layer is made of, for example, any one of the following light absorbing materials (i) to (iii).

(i) Silver oxide or copper oxide

(ii) At least one selected from the group consisting of copper nitride, copper oxide, nickel nitride and nickel oxide

(iii) Any one of zinc, an alloy of copper and zinc, and an alloy of silver and zinc

When the blackened layer is composed of the above-mentioned (i), there can be mentioned: a method of forming a layer containing an oxide of silver or an oxide of copper by evaporation or plating. As the vapor deposition method, for example, a known vapor deposition method such as a vacuum vapor deposition method or a sputtering method can be used.

When the blackened layer is composed of the above (ii), there may be mentioned: a method of forming a layer containing at least one selected from the group consisting of copper nitride, copper oxide, nickel nitride, and nickel oxide by evaporation or plating.

When the blackening layer is composed of the above-mentioned (iii), there can be mentioned: a method of forming a layer containing any one of zinc, an alloy of copper and zinc, and an alloy of silver and zinc by evaporation or plating.

The thickness of the black layer is not particularly limited, but is preferably 5nm or more and 20 μm or less, and more preferably 10nm or more and 1 μm or less. If the thickness of the blackening layer is not less than the lower limit value, light reflection can be sufficiently suppressed; if the upper limit value is less than the above-mentioned upper limit value, the blackening layer can be easily formed.

[ Anisotropic conductive adhesive layer ]

The anisotropic conductive adhesive layer 24 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 24 can easily reduce the thickness of the conductive adhesive layer, and can reduce the amount of conductive particles described later, and as a result, has an advantage that the electromagnetic wave shielding film 1 can be reduced in thickness and the flexibility of the electromagnetic wave shielding film 1 can be improved.

As the anisotropic conductive adhesive layer 24, a thermosetting conductive adhesive layer is preferable in terms of the ability to exhibit heat resistance after curing. The thermosetting anisotropic conductive adhesive layer 24 may be in an uncured state or in a B-stage state.

The thermosetting anisotropic conductive adhesive layer 24 contains, for example, a thermosetting adhesive 24a and conductive particles 24 b. The anisotropic conductive adhesive layer 24 may contain a flame retardant as necessary.

Examples of the thermosetting adhesive 24a include: epoxy resins, phenol resins, amino resins, alkyd resins, polyurethane resins, synthetic rubbers, ultraviolet-curing acrylate resins, and the like. Epoxy resins are preferred in view of their excellent heat resistance. The epoxy resin may contain a rubber component (carboxyl-modified nitrile rubber, acrylic rubber, or the like) for imparting flexibility, a tackifier, and the like.

The thermosetting adhesive 24a may contain a cellulose resin or microfibers (e.g., glass fibers) in order to improve the strength of the anisotropic conductive adhesive layer 24 and to improve the punching property. The thermosetting adhesive may contain other components as necessary within a range not impairing the effects of the present invention.

As the conductive particles 24b, there can be mentioned: metal (silver, platinum, gold, copper, nickel, palladium, aluminum, solder, etc.) particles, graphite powder, sintered carbon particles, plated sintered carbon particles, and the like. As the conductive particles 24b, metal particles are preferable, and copper particles are more preferable, from the viewpoint of making the anisotropic conductive adhesive layer 24 have more appropriate hardness and further reducing the pressure loss of the anisotropic conductive adhesive layer 24 at the time of hot pressing.

The 10% compressive strength of the conductive particles 24b is preferably 30MPa or more and 200MPa or less, more preferably 50MPa or more and 150MPa or less, and further preferably 70MPa or more and 100MPa or less. If the 10% compressive strength of the conductive particles is not less than the lower limit of the above range, the pressure loss applied to the metal thin film layer 22 is not excessively large at the time of hot pressing, and the anisotropic conductive adhesive layer 24 is electrically connected to the printed circuit of the printed wiring board more reliably via the through hole of the insulating film. If the 10% compressive strength of the conductive particles 24b is not more than the upper limit of the above range, the contact with the metal thin film layer 22 becomes good, and the electrical connection becomes reliable.

The conductive particles 24b in the anisotropic conductive adhesive layer 24 have an average particle diameter of 2 μm or more and 26 μm or less, and more preferably 4 μm or more and 16 μm or less. If the average particle diameter of the conductive particles 24b is not less than the lower limit of the above range, the thickness of the anisotropic conductive adhesive layer 24 can be secured, and sufficient adhesive strength can be obtained. If the average particle diameter of the conductive particles 24b is not more than the upper limit of the above range, the fluidity of the anisotropic conductive adhesive layer 24 can be ensured, and as described below, when the anisotropic conductive adhesive layer 24 is pressed into the through holes of the insulating film, the inside of the through holes of the insulating film can be sufficiently filled with the conductive adhesive.

The proportion of the conductive particles 24b in the anisotropic conductive adhesive layer 24 is preferably 1 vol% or more and 30 vol% or less, and more preferably 2 vol% or more and 15 vol% or less, of 100 vol% of the anisotropic conductive adhesive layer 24. If the ratio of the conductive particles 24b is not less than the lower limit of the above range, the conductivity of the anisotropic conductive adhesive layer 24 becomes good. If the ratio of the conductive particles 24b is not more than the upper limit of the above range, the adhesiveness and flowability (conformability to the shape of the through-hole of the insulating film) of the anisotropic conductive adhesive layer 24 become good. In addition, the flexibility of the electromagnetic wave shielding film 1 becomes good.

The storage modulus at 180 ℃ of the anisotropic conductive adhesive layer 24 is preferably 1 × 10³Pa or more and 5X 10⁷Pa or less, more preferably 5X 10³Pa or more and 1X 10⁷Pa or less.If the storage modulus at 180 ℃ of the anisotropic conductive adhesive layer 24 is not less than the lower limit of the above range, the anisotropic conductive adhesive layer 24 has more appropriate hardness, and the pressure loss on the conductive adhesive layer at the time of hot pressing can be reduced. As a result, the conductive adhesive layer and the printed circuit of the printed wiring board are sufficiently adhered, and the anisotropic conductive adhesive layer 24 is electrically connected to the printed circuit of the printed wiring board more reliably through the through hole of the insulating film. If the storage modulus of the conductive adhesive layer at 180 ℃ is not more than the upper limit of the above range, the flexibility of the electromagnetic wave shielding film 1 becomes good. As a result, the electromagnetic wave shielding film 1 is likely to sink into the through hole of the insulating film, and the anisotropic conductive adhesive layer 24 is electrically connected to the printed circuit of the printed wiring board more reliably via the through hole of the insulating film.

The surface resistance of the anisotropic conductive adhesive layer 24 is preferably 1 × 10⁴Omega is 1 × 10 or more¹⁶Omega or less, more preferably 1X 10⁶Omega is 1 × 10 or more¹⁴Omega is less than or equal to. If the surface resistance of the anisotropic conductive adhesive layer 24 is not less than the lower limit of the above range, the content of the conductive particles 24b can be controlled to be low.

If the surface resistance of the anisotropic conductive adhesive layer 24 is not more than the upper limit of the above range, there is no problem in the anisotropy in practical use.

The thickness of the anisotropic conductive adhesive layer 24 is preferably 3 μm or more and 25 μm or less, and more preferably 5 μm or more and 15 μm or less. If the thickness of the anisotropic conductive adhesive layer 24 is not less than the lower limit of the above range, the fluidity of the anisotropic conductive adhesive layer 24 (the adaptability to 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 sufficiently filled with the conductive adhesive. If the thickness of the anisotropic conductive adhesive layer 24 is not more than the upper limit of the above range, the electromagnetic wave shielding film 1 can be made thin. In addition, the flexibility of the electromagnetic wave shielding film 1 becomes good.

[ Isotropic conductive adhesive layer ]

The isotropic conductive adhesive layer 26 in the second or third embodiment is conductive in the thickness direction and the surface direction, and has adhesiveness.

The isotropic conductive adhesive layer 26 has an advantage that the electromagnetic wave shielding property of the electromagnetic wave shielding film 1 can be further improved.

As the isotropic conductive adhesive layer 26, a thermosetting conductive adhesive layer is preferable in terms of the ability to exhibit heat resistance after curing. The thermosetting isotropic conductive adhesive layer 26 may be in an uncured state or in a B-stage state.

The thermosetting isotropic conductive adhesive layer 26 includes, for example, a thermosetting adhesive 26a and conductive particles 26 b. The thermosetting isotropic conductive adhesive layer 26 may contain a flame retardant as necessary.

The components of the thermosetting adhesive 26a and the materials of the conductive particles 26b contained in the isotropic conductive adhesive layer 26 are the same as those of the thermosetting adhesive 24a and the materials of the conductive particles 24b contained in the anisotropic conductive adhesive layer 24.

The average particle diameter of the conductive particles 26b in the isotropic conductive adhesive layer 26 is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.2 μm or more and 1 μm or less. If the average particle diameter of the conductive particles 26b is equal to or larger than the lower limit of the above range, the number of contact points of the conductive particles 26b increases, and the conductivity in the three-dimensional direction can be stably improved. If the average particle diameter of the conductive particles 26b is not more than the upper limit of the above range, the fluidity of the isotropic conductive adhesive layer 26 (the adaptability to 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 sufficiently filled with the conductive adhesive.

The proportion of the conductive particles 26b in the isotropic conductive adhesive layer 26 is preferably 50 vol% or more and 80 vol% or less, and more preferably 60 vol% or more and 70 vol% or less, of 100 vol% of the isotropic conductive adhesive layer 26. If the ratio of the conductive particles 26b is not less than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 26 becomes good. When the ratio of the conductive particles 26b is not more than the upper limit of the above range, the adhesiveness and fluidity (conformability to the shape of the through hole of the insulating film) of the isotropic conductive adhesive layer 26 become good. In addition, the flexibility of the electromagnetic wave shielding film 1 becomes good.

The storage modulus of the isotropic conductive adhesive layer 26 at 180 ℃ is preferably 1X 10³Pa or more and 5X 10⁷Pa or less, more preferably 5X 10³Pa or more and 1X 10⁷Pa or less. The reason why the above range is preferable is the same as that of the anisotropic conductive adhesive layer 24.

The surface resistance of the isotropic conductive adhesive layer 26 is preferably 0.05 Ω to 2.0 Ω, and more preferably 0.1 Ω to 1.0 Ω. If the surface resistance of the isotropic conductive adhesive layer 26 is not less than the lower limit of the above range, the content of the conductive particles 26b can be controlled to be low, the viscosity of the conductive adhesive is not excessively high, and the coatability is further improved. In addition, the fluidity of the isotropic conductive adhesive layer 26 (the conformability to the shape of the through-hole of the insulating film) can be further ensured. If the surface resistance of the isotropic conductive adhesive layer 26 is not more than the upper limit of the above range, the entire surface of the isotropic conductive adhesive layer 26 has uniform conductivity.

The thickness of isotropic conductive adhesive layer 26 is preferably 5 μm or more and 20 μm or less, and more preferably 7 μm or more and 17 μm or less. If the thickness of the isotropic conductive adhesive layer 26 is not less than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 26 becomes good, and the electromagnetic wave shielding layer can function sufficiently. Further, the fluidity of the isotropic conductive adhesive layer 26 (the conformability to the shape of the through hole of the insulating film) can be ensured, the inside of the through hole of the insulating film can be sufficiently filled with the conductive adhesive, the folding endurance can be ensured, and the isotropic conductive adhesive layer 26 is not broken even when repeatedly bent.

If the thickness of the isotropic conductive adhesive layer 26 is not more than the upper limit of the above range, the electromagnetic wave shielding film 1 can be made thin. In addition, the flexibility of the electromagnetic wave shielding film 1 becomes good.

(Carrier film)

The carrier film 30 is a support for reinforcing and protecting the insulating resin layer 10 and the conductive layer 20, and improves the workability of the electromagnetic wave shielding film 1. In particular, when a thin film, specifically, a film having a thickness of 3 μm or more and 10 μm or less is used as the insulating resin layer 10, the carrier film 30 can prevent the insulating resin layer 10 from being broken.

After the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like, the carrier film 30 is peeled from the insulating resin layer 10.

The carrier film 30 used in the present embodiment has a carrier film main body 32 and an adhesive layer 34 provided on the surface of the carrier film main body 32 on the insulating resin layer 10 side.

Examples of the resin material of the carrier film main body 32 include: polyethylene terephthalate (hereinafter, also 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, and the like. As the resin material, PET is preferable from the viewpoint of heat resistance (dimensional stability) and price in the production of the electromagnetic wave shielding film 1.

The carrier film body 32 may include either or both of a colorant (pigment, dye, etc.) and a filler.

Either or both of the colorant and the filler are preferably different in color from the insulating resin layer 10, and more preferably white pigment, filler, or a combination of white pigment and other pigment or filler, in terms of being clearly distinguishable from the insulating resin layer 10 and allowing the peeling residue of the carrier film 30 to be easily found after the hot pressing.

The storage modulus at 180 ℃ of the carrier film body 32 is preferably 8 × 10⁷Pa or more and 5X 10⁹Pa or less, more preferably 1X 10⁸Pa or more and 8X 10⁸Pa or less. If the storage modulus at 180 ℃ of the carrier film main body 32 is above the lower limit of the above range, the carrier film 30 has a suitable hardness, which can be reducedPressure loss on the carrier film 30 at low heat press. If the storage modulus at 180 ℃ of the carrier film main body 32 is not more than the upper limit value of the above range, the flexibility of the carrier film 30 becomes good.

The thickness of the carrier film main body 32 is preferably 3 μm or more and 75 μm or less, and more preferably 12 μm or more and 50 μm or less. If the thickness of the carrier film main body 32 is equal to or greater than the lower limit of the above range, the electromagnetic wave shielding film 1 is excellent in handling properties. If the thickness of the carrier film main body 32 is not more than the upper limit of the above range, heat is easily conducted to the conductive adhesive layer when the conductive adhesive layer (the anisotropic conductive adhesive layer 24 or the isotropic conductive adhesive layer 26) of the electromagnetic wave shielding film 1 is hot-pressed on the surface of the insulating film.

The adhesive layer 34 is formed by, for example, applying an adhesive composition containing an adhesive to the surface of the carrier film main body 32. By providing the carrier film 30 with the pressure-sensitive adhesive layer 34, the carrier film 30 can be inhibited from peeling from the insulating resin layer 10 when the release film 40 is peeled from the conductive adhesive layer or when the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like by hot pressing. Therefore, the carrier film 30 can sufficiently function as a protective film.

The pressure-sensitive adhesive is preferably a substance that imparts appropriate adhesiveness to the pressure-sensitive adhesive layer 34, where appropriate adhesiveness is a degree that the carrier film 30 is not easily peeled from the insulating resin layer 10 before hot pressing and the carrier film 30 can be peeled from the insulating resin layer 10 after hot pressing.

Examples of the binder include: acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives, and the like.

The glass transition temperature of the binder is preferably-100 ℃ or higher and 60 ℃ or lower, and more preferably-60 ℃ or higher and 40 ℃ or lower.

The thickness of the carrier film 30 is preferably 25 μm or more and 125 μm or less, and more preferably 38 μm or more and 100 μm or less. If the thickness of the carrier film 30 is equal to or greater than the lower limit of the above range, the electromagnetic wave shielding film 1 is excellent in handling properties. If the thickness of the carrier film 30 is not more than the upper limit of the above range, heat is easily transferred to the conductive adhesive layer of the electromagnetic wave shielding film 1 when the conductive adhesive layer is hot-pressed on the surface of the insulating film.

(mold release film)

The release film 40 protects the conductive adhesive layer (the anisotropic conductive adhesive layer 24 or the isotropic conductive adhesive layer 26) and improves the handling properties of the electromagnetic wave shielding film 1. Before the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like, the release film 40 is peeled off from the conductive adhesive layer (the anisotropic conductive adhesive layer 24 or the isotropic conductive adhesive layer 26).

The release film 40 includes, for example, a release film main body 42 and a release agent layer 44 provided on a surface of the release film main body 42 on the conductive adhesive layer side.

As the resin material of the release film main body 42, the same resin material as that of the carrier film main body 32 can be cited.

The release film main body 42 may contain a colorant, a filler, and the like.

The thickness of the release film main body 42 is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 150 μm or less, and further preferably 25 μm or more and 100 μm or less.

The surface of the release film main body 42 is treated with a release agent to form a release agent layer 44. By providing the release film 40 with the release agent layer 44, the release film 40 is easily peeled off when the release film 40 is peeled off from the conductive adhesive layer, and the conductive adhesive layer is less likely to break.

As the release agent, a known release agent may be used.

The thickness of the release agent layer 44 is preferably 0.05 μm or more and 30 μm or less, and more preferably 0.1 μm or more and 20 μm or less. If the thickness of the release agent layer 44 is within the above range, the release film 40 is more easily peeled.

(thickness of electromagnetic wave shielding film)

The thickness of the electromagnetic wave-shielding film 1 (excluding the carrier film 30 and the release film 40) 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 not including the carrier film 30 and the release film 40 is not less than the lower limit of the above range, the carrier film 30 is not easily broken when peeled off. If the thickness of the electromagnetic wave shielding film 1 not including the carrier film 30 and the release film 40 is not more than the upper limit of the above range, the printed wiring board with the electromagnetic wave shielding film can be thinned.

< method for producing electromagnetic wave shielding film >

A second aspect of the present invention is a method for manufacturing an electromagnetic wave shielding film, including the steps of: forming a mixed resin of an aromatic polyether ketone and a polyether imide into a film shape to form an insulating resin layer; and forming a conductive layer on one surface of the insulating resin layer.

Specifically, as a method for manufacturing the electromagnetic wave shielding film of the first embodiment, the following method (a1) and method (a2) can be cited. As a method for manufacturing the electromagnetic wave shielding film of the second embodiment, the following method (B1) and method (B2) can be cited. As a method for manufacturing the electromagnetic wave shielding film of the third embodiment, the following method (C1) and method (C2) can be cited.

The method (A1) includes the following steps (A1-1) to (A1-4).

Step (A1-1): and a step of molding a mixed resin of an aromatic polyether ketone and a polyether imide into a film shape, and laminating the insulating resin layer 10 formed on the carrier film 30.

Step (A1-2): and a step of forming the metal thin film layer 22 on the surface of the insulating resin layer 10 opposite to the carrier film 30.

Step (A1-3): and a step of forming an anisotropic conductive adhesive layer 24 on the surface of the metal thin film layer 22 opposite to the insulating resin layer 10.

Step (A1-4): and a step of laminating a release film 40 on the surface of the anisotropic conductive adhesive layer 24 opposite to the metal thin film layer 22.

Next, each step of the method (a1) will be described in detail.

In the step (a1-1), a mixed resin of an aromatic polyether ketone and a polyether imide is molded into a film shape. Examples of the molding method include: the melt extrusion molding method, the calender molding method, the casting method, and the like are preferably melt extrusion molding methods from the viewpoint of simplifying facilities.

In the melt extrusion molding method, the resin is melt-kneaded by a melt extrusion molding machine, and is continuously extruded into a ribbon shape from a T-die provided at the tip of the melt extrusion molding machine, thereby molding the resin into a film shape. The preferred temperature for melt kneading is as described above.

The water content of the resin supplied to the melt extrusion molding machine is preferably 0ppm to 5000ppm, and more preferably 0ppm to 2000 ppm. If the water content of the resin is below the upper limit, the resin can be prevented from foaming.

In order to prevent the above-mentioned oxidative deterioration and oxygen crosslinking of the resin during melt kneading, it is preferable to make the supply port of the melt extrusion molding machine an inert gas atmosphere. As the inert gas, for example, there can be used: helium, neon, argon, krypton, nitrogen, carbon dioxide, and the like.

The molten film extruded from the T-die is preferably cooled against a metal roll. The temperature of the metal roll is preferably lower than the melting point of the resin, and more preferably not higher than the crystallization temperature. If the temperature of the metal roller is lower than the melting point of the above resin, film breakage can be prevented.

The thus obtained film-like insulating resin layer 10 is laminated on the surface of the carrier film 30 on which the pressure-sensitive adhesive layer 34 is provided.

When the conductive layer 20 has a blackened layer, the blackened layer may be formed on the insulating resin layer 10 obtained as described above by vapor deposition, plating, or the like.

Examples of the method for forming the metal thin film layer in the step (a1-2) include: a method of forming a vapor deposition film by physical vapor deposition or CVD (chemical vapor deposition), a method of forming a plating film by plating, a method of attaching a metal foil, and the like. In order to form a metal thin film layer having excellent conductivity in the plane direction, a method of forming a vapor deposited film by physical vapor deposition or CVD, or a method of forming a plating film by plating is preferable. From the viewpoint that the thickness of the metal thin film layer can be reduced, a metal thin film layer excellent in conductivity in the plane direction can be formed even if the thickness is small, and the metal thin film layer can be easily formed by a dry process, a method of forming a vapor deposited film by physical vapor deposition or CVD is more preferable, and a method of forming a vapor deposited film by physical vapor deposition is even more preferable.

In the step (a1-3), the conductive adhesive paint is applied to the surface of the metal thin film layer 22 opposite to the insulating resin layer 10. The conductive adhesive coating material contains a thermosetting adhesive 24a, conductive particles 24b, and a solvent. The anisotropic conductive adhesive layer 24 is formed by volatilizing the solvent from the applied conductive adhesive coating material.

Examples of the solvent contained in the conductive adhesive coating material 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.), alcohols (methanol, ethanol, isopropanol, butanol, propylene glycol monomethyl ether, propylene glycol, etc.), and the like.

As a method for applying the conductive adhesive, for example, a method using the following various coating machines can be applied: various coaters such as die coater, gravure coater, roll coater, curtain flow coater, spin coater, bar coater, reverse roll coater, kiss coater, jet draw coater, bar coater, air knife coater, blade coater, casting coater, and screen coater.

In the step (a1-4), the release film 40 is laminated on the surface of the anisotropic conductive adhesive layer 24 opposite to the metal thin film layer 22 so that the release agent layer 44 is in contact with the anisotropic conductive adhesive layer 24.

After the release film 40 is laminated on the anisotropic conductive adhesive layer 24, a laminate including the carrier film 30, the insulating resin layer 10, the metal thin film layer 22, the anisotropic conductive adhesive layer 24, and the release film 40 is subjected to pressure treatment to improve the adhesion between the layers.

The pressure in the pressurization treatment is preferably 0.1kPa to 100kPa, more preferably 0.1kPa to 20kPa, and still more preferably 1kPa to 10 kPa.

The heating may be performed simultaneously with the pressurization treatment. The heating temperature in this case is preferably 50 ℃ or higher and 100 ℃ or lower.

The method (A2) includes the following steps (A2-1) to (A2-4).

Step (A2-1): and a step of molding a mixed resin of an aromatic polyether ketone and a polyether imide into a film shape, and laminating the insulating resin layer 10 formed on the carrier film 30.

Step (A2-2): and (d) forming the metal thin film layer 22 on the surface of the insulating resin layer 10 opposite to the carrier film 30 to form a laminate (I).

Step (A2-3): and (d) forming the anisotropic conductive adhesive layer 24 on the release film 40 to form a laminate (II).

Step (A2-4): and (d) bonding the laminate (I) and the laminate (II) so that the metal thin film layer 22 of the laminate (I) is in contact with the anisotropic conductive adhesive layer 24 of the laminate (II).

The step (A2-1) and the step (A2-2) are the same as the step (A1-1) and the step (A1-2) in the above-mentioned method (A1).

In the step (a2-3), the conductive adhesive coating is applied to the surface of the release film 40 on which the release agent layer 44 is provided. The anisotropic conductive adhesive layer 24 is formed by volatilizing the solvent from the applied conductive adhesive paint. The conductive adhesive coating material and the coating method are the same as in the step (a1-3) in the above-described method (a).

In the step (a2-4), when the laminate (I) and the laminate (II) are bonded, heat treatment may be performed to improve the adhesion between the laminate (I) and the laminate (II). The pressing conditions were the same as those in the pressing treatment in the step (A1-4). In the step (A2-4), heating may be performed in the same manner as in the step (A1-4).

The method (B1) is the same as the method (a1) except that the conductive adhesive paint is changed to a paint containing a thermosetting adhesive 26a, conductive particles 26B, and a solvent, thereby forming the isotropic conductive adhesive layer 26.

The method (B2) is the same as the method (a2) except that the conductive adhesive paint is changed to a paint containing a thermosetting adhesive 26a, conductive particles 26B, and a solvent, thereby forming the isotropic conductive adhesive layer 26.

The method (C1) has the following steps (C1-1) to (C1-3).

Step (C1-1): and a step of molding a mixed resin of an aromatic polyether ketone and a polyether imide into a film shape, and laminating the insulating resin layer 10 formed on the carrier film 30.

Step (C1-2): and a step of forming an isotropic conductive adhesive layer 26 on the surface of the insulating resin layer 10 opposite to the carrier film 30.

Step (C1-3): and a step of laminating a release film 40 on the surface of the isotropic conductive adhesive layer 26 opposite to the insulating resin layer 10.

The method (C1) is the same as the method (a1) except that the formation of the metal thin film layer is omitted, and the isotropic conductive adhesive layer 26 is formed directly on the insulating resin layer 10 using an isotropic conductive adhesive as the conductive adhesive.

The method (C2) has the following steps (C2-1) to (C2-3).

Step (C2-1): and (b) forming a mixed resin of an aromatic polyether ketone and a polyether imide into a film, and laminating the formed insulating resin layer 10 on the carrier film 30 to form a laminate (I).

Step (C2-2): and (II) forming an isotropic conductive adhesive layer 26 on the release film 40 to form a laminate (II).

Step (C2-3): and a step of bonding the laminate (I) and the laminate (II) so that the insulating resin layer 10 of the laminate (I) is in contact with the isotropic conductive adhesive layer 26 of the laminate (II).

The method (C2) is the same as the method (a2) except that the metal thin film layer is not formed, an isotropic conductive adhesive is used as the conductive adhesive, and the isotropic conductive adhesive layer 26 is bonded to the insulating resin layer 10.

(Effect)

According to the electromagnetic wave shielding film 1 of the present embodiment in which the insulating resin layer 10 contains the mixed resin of the aromatic polyether ketone and the polyether imide, the adhesion of the insulating resin layer 10 to the conductive layer 20 containing the metal can be improved. Therefore, the insulating resin layer 10 and the conductive layer 20 can be prevented from being delaminated from each other during the processing of the electromagnetic wave shielding film 1. This effect is particularly exhibited when the conductive layer 20 has the metal thin film layer 22, and the insulating resin layer 10 containing a mixed resin of an aromatic polyether ketone and a polyether imide is bonded to the metal thin film layer 22 with high adhesion.

(other embodiments)

The electromagnetic wave shielding film of the present embodiment is not limited to the above-described embodiments.

For example, when the surface adhesive force of the anisotropic conductive adhesive layer 24 or the isotropic conductive adhesive layer 26 is small, the release film 40 may be omitted.

When the insulating resin layer 10 has sufficient flexibility and strength, the carrier film 30 may be omitted.

In the case where the carrier film body 32 is a film having self-adhesion, the carrier film 30 may omit the adhesive layer 34.

In the case where the release film main body 42 alone has sufficient releasability, the release film 40 may omit the release agent layer 44.

< printed wiring board with electromagnetic wave shielding film >

A third aspect of the present invention is a printed wiring board with an electromagnetic wave shielding film, comprising: a printed wiring board having a printed circuit provided on at least one surface of a substrate; an insulating film adjacent to a surface of the printed wiring board on which the printed circuit is provided; and an electromagnetic wave shielding film of the above aspect, provided such that the adhesive layer is adjacent to the insulating film.

Fig. 4 is a cross-sectional view showing one embodiment of the printed wiring board with an electromagnetic wave shielding film of the present embodiment.

The electromagnetic wave shielding film-equipped printed wiring board 2 includes a flexible printed wiring board 50, an insulating film 60, and the electromagnetic wave shielding film 1 of the first embodiment.

The flexible printed wiring board 50 is provided with a printed circuit 54 on at least one surface of a base film 52.

The insulating film 60 is provided on the surface of the flexible printed wiring board 50 on the side where the printed circuit 54 is provided.

The anisotropic conductive adhesive layer 24 of the electromagnetic wave shielding film 1 is adhered to the surface of the insulating film 60 and cured. The anisotropic conductive adhesive layer 24 is electrically connected to the printed circuit 54 through a through hole (not shown) formed in the insulating film 60.

In the printed wiring board 2 with an electromagnetic wave shielding film, the release film is peeled off from the anisotropic conductive adhesive layer 24.

When the carrier film 30 is not required in the printed wiring board with electromagnetic wave shielding film 2, the carrier film 30 is peeled off from the insulating resin layer 10.

The metal thin film layer 22 of the electromagnetic wave shielding film 1 is disposed facing the printed circuit 54 (signal circuit, ground layer, etc.) except for the portion having the through hole, with the insulating film 60 and the anisotropic conductive adhesive layer 24 interposed therebetween.

The distance between the printed circuit 54 and the metal thin film layer 22 except for the portion having the through-hole is substantially equal to the sum of the thickness of the insulating film 60 and the thickness of the anisotropic conductive adhesive layer 24. The separation distance is preferably 30 μm or more and 200 μm or less, and more preferably 60 μm or more and 200 μm or less. If the spacing distance is less than 30 μm, the resistance of the signal circuit decreases, and therefore, in order to have a characteristic resistance of 100 Ω or the like, the line width of the signal circuit must be reduced, and the instability of the line width becomes the instability of the characteristic resistance, and the reflection resonance noise due to the resistance mismatch is easily mixed into the electric signal. If the separation distance is more than 200 μm, the printed wiring board 2 with the electromagnetic wave shielding film becomes thick and insufficient in flexibility.

(Flexible printed Wiring Board)

The flexible printed wiring board 50 is a printed circuit 54 formed by processing the copper foil of the copper-clad laminate into a desired pattern by a known etching method.

Examples of the copper-clad laminate include: a sheet having copper foil adhered to one or both surfaces of base film 52 with an adhesive layer (not shown); a plate or the like obtained by casting a resin solution or the like for forming the base film 52 on the surface of the copper foil.

Examples of the material of the adhesive layer include: epoxy resins, polyesters, polyimides, polyamideimides, polyamides, phenol resins, polyurethane resins, acrylic resins, melamine resins, and the like.

The thickness of the adhesive layer is preferably 0.5 μm or more and 30 μm or less.

[ base film ]

The base film 52 is preferably a film having heat resistance, more preferably a polyimide film, a polyetherimide film, a polyphenylene sulfide film, or a liquid crystal polymer film, and further preferably a polyimide film.

The surface resistance of the base film 52 is preferably 1 × 10 in view of electrical insulation⁶Omega or more. From the practical viewpoint, the surface resistance of the base film 52 is preferably 1 × 10¹⁹Omega is less than or equal to.

The thickness of the base film 52 is preferably 5 μm or more and 200 μm or less, more preferably 6 μm or more and 50 μm or less, and still more preferably 10 μm or more and 25 μm or less, from the viewpoint of flexibility.

[ printed Circuit ]

Examples of the copper foil constituting the printed circuit 54 include: rolled copper foil, electrolytic copper foil, and the like, rolled copper foil is preferred in view of bendability. The printed circuit 54 may be used, for example, as a signal circuit, a ground layer, and the like.

The thickness of the copper foil is preferably 1 μm or more and 50 μm or less, and more preferably 18 μm or more and 35 μm or less.

The end portions (terminals) of the printed circuit 54 in the longitudinal direction are exposed without being covered with the insulating film 60 or the electromagnetic wave shielding film 1, and are connected with solder, a connection terminal, a mounting member, and the like.

(insulating film)

The insulating film 60 (cover film) is a film in which an adhesive layer (not shown) is formed on one surface of an insulating film main body (not shown) by applying an adhesive, attaching an adhesive sheet, or the like.

From the viewpoint of electrical insulation, the surface resistance of the insulating film body is preferably 1 × 10⁶Omega or more. From the practical viewpoint, the surface resistance of the insulating film body is preferably 1X 10¹⁹Omega is less than or equal to.

The insulating film main body is preferably a film having heat resistance, more preferably a polyimide film, a polyetherimide film, a polyphenylene sulfide film, or a liquid crystal polymer film, and further preferably a polyimide film.

The thickness of the insulating film main 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 the material of the adhesive layer include: epoxy resins, polyesters, polyimides, polyamideimides, polyamides, phenol resins, polyurethane resins, acrylic resins, melamine resins, polystyrenes, polyolefins, and the like. The epoxy resin may contain a rubber component (carboxyl-modified nitrile rubber or the like) for imparting 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.

The shape of the opening of the through hole formed in the insulating film 60 is not particularly limited. Examples of the shape of the opening of the through hole include a circle, an ellipse, and a quadrangle.

< method for manufacturing printed wiring board with electromagnetic wave shielding film >

A method for manufacturing a printed wiring board with an electromagnetic wave shielding film according to a fourth aspect of the present invention includes the steps of: the electromagnetic wave shielding film of the above-described embodiment is pressure-bonded to a printed wiring board having a printed circuit on at least one surface of a substrate, with an insulating film interposed therebetween, and the insulating film is brought into close contact with the surface of the printed wiring board on which the printed circuit is provided and with the conductive adhesive layer of the electromagnetic wave shielding film during the pressure bonding.

The electromagnetic wave shielding film-attached printed wiring board 2 of the above embodiment can be manufactured, for example, by a method including the following steps (a) to (d) (see fig. 5).

A step (a): and a step of providing an insulating film 60 on the surface of the flexible printed wiring board 50 on the side where the printed circuit 54 is provided, the insulating film 60 having a through hole 62 formed at a position corresponding to the printed circuit 54, and obtaining the insulating film-equipped printed wiring board 3.

A step (b): after the step (a), the printed wiring board 3 with the insulating film and the electromagnetic wave shielding film 1 from which the release film 40 has been peeled are stacked so that the anisotropic conductive adhesive layer 24 is in contact with the surface of the insulating film 60, and then they are pressure-bonded.

A step (c): and (d) peeling the carrier film 30 when the carrier film 30 is not needed after the step (b).

Step (d): and (c) a step of main curing the anisotropic conductive adhesive layer 24 between the steps (a) and (b) or after the step (c), as required.

Next, each step will be described in detail with reference to fig. 5.

(Process (a))

The step (a) is a step of obtaining the insulating film-equipped printed wiring board 3 by laminating the insulating film 60 on the flexible printed wiring board 50.

Specifically, first, the insulating film 60 in which the through-hole 62 is formed at a position corresponding to the printed circuit 54 is superimposed on the flexible printed wiring board 50. Next, an adhesive layer (not shown) of the insulating film 60 is adhered to the surface of the flexible printed wiring board 50 and the adhesive layer is cured, thereby obtaining the insulating film-equipped printed wiring board 3. The adhesive layer of the insulating film 60 may be temporarily adhered to the surface of the flexible printed wiring board 50, and the adhesive layer may be cured in step (d).

The adhesive layer is bonded and cured by hot pressing using, for example, a press (not shown).

(Process (b))

The 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 after peeling the release film 40 is stacked on the printed wiring board 3 with an insulating film, and is pressure-bonded by hot pressing or the like. Thereby, the anisotropic conductive adhesive layer 24 is adhered to the surface of the insulating film 60, and the anisotropic conductive adhesive layer 24 is pressed into the through-hole 62 to fill the inside of the through-hole 62, thereby electrically connecting to the printed circuit 54. Thereby, the printed wiring board 2 with the electromagnetic wave shielding film was obtained.

The anisotropic conductive adhesive layer 24 is bonded and cured by hot pressing using, for example, 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 not less than the lower limit of the above range, the anisotropic conductive adhesive layer 24 can be easily adhered to the surface of the insulating film 60. If the hot pressing time is not more than the upper limit of the above range, the time for manufacturing the printed wiring board 2 with an electromagnetic wave shielding film can be shortened.

The hot pressing temperature (temperature of a hot plate of a press) is preferably 140 ℃ or more and 190 ℃ or less, and more preferably 150 ℃ or more and 175 ℃ or less. If the hot-pressing temperature is not lower than the lower limit of the above range, the anisotropic conductive adhesive layer 24 can be easily adhered to the surface of the insulating film 60. In addition, the hot pressing time can be shortened. If the hot pressing temperature is not more than the upper limit of the above range, deterioration of the electromagnetic wave shielding film 1, the flexible printed wiring board 50, and the like can be easily suppressed.

The pressure of the hot pressing is preferably 0.5MPa to 20MPa, more preferably 1MPa to 16 MPa. If the pressure of the hot pressing is not less than the lower limit of the above range, the anisotropic conductive adhesive layer 24 can be bonded to the surface of the insulating film 60. In addition, the hot pressing time can be shortened. If the pressure of the hot pressing is not more than the upper limit of the above range, damage and the like to the electromagnetic wave shielding film 1, the flexible printed wiring board 50 and the like can be suppressed.

(step (c))

The step (c) is a step of peeling the carrier film 30.

Specifically, when the carrier film is not needed, the carrier film 30 is peeled from the insulating resin layer 10.

(Process (d))

Step (d) is a step of main curing the anisotropic conductive adhesive layer 24.

When the hot press time in step (b) is short, not less than 20 seconds and not more than 10 minutes, it is preferable to perform main curing of the anisotropic conductive adhesive layer 24 between step (b) and step (c) or after step (c).

The main curing of the anisotropic conductive adhesive layer 24 is performed using a heating device such as an oven, for example.

The heating time is preferably 15 minutes to 120 minutes, more preferably 30 minutes to 60 minutes. If the heating time is not less than the lower limit of the above range, the anisotropic conductive adhesive layer 24 can be sufficiently cured. If the heating time is not more than the upper limit of the above range, the time required for manufacturing the printed wiring board 2 with an electromagnetic wave shielding film can be shortened.

The heating temperature (the temperature of the atmosphere in the oven) is preferably 120 ℃ or more and 180 ℃ or less, and more preferably 120 ℃ or more and 150 ℃ or less. If the heating temperature is not lower than the lower limit of the above range, the heating time can be shortened. If the heating temperature is not more than the upper limit of the above range, deterioration of the electromagnetic wave-shielding film 1, the flexible printed wiring board 50, and the like can be suppressed.

(Effect)

Since the electromagnetic wave shielding film 1 is used in the electromagnetic wave shielding film-equipped printed wiring board of the present embodiment, the adhesion between the insulating resin layer 10 and the conductive layer 20 containing metal is sufficiently high. Therefore, interlayer peeling between the insulating resin layer 10 and the conductive layer 20 can be prevented.

(other embodiments)

The electromagnetic wave shielding film-attached printed wiring board of the present embodiment is not limited to the above-described embodiments.

For example, the flexible printed wiring board 50 may have a ground layer on the back side. The flexible printed wiring board 50 may have the printed circuit 54 on both surfaces, and the insulating film 60 and the electromagnetic wave shielding film 1 may be attached to both surfaces.

A rigid printed board having no flexibility may be used instead of the flexible printed wiring board 50.

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.

Examples

[ example 1]

(preparation of Mixed resin and film Forming)

First, PEEK (product name of Solvay Specialty Polymers Co., Ltd.): ketarse polyetheretherketone brand name: KT-851NL SP and PEI [ product name manufactured by SABIC Co., Ltd.: ULTEM, 9011-NB, glass transition temperature: 210 ℃ in a composition mass ratio of PEEK: 90 mass%, PEI: 10% by mass was charged into a drum mixer, and the drum mixer was stirred and mixed at 23 ℃ for 1 hour to prepare a stirred mixture.

A stirred mixture obtained by stirring and mixing PEEK and PEI was supplied to a twin-screw extrusion molding machine equipped with a vacuum pump, and melt-kneaded under reduced pressure, extruded into a rod shape from a die at the tip of the twin-screw extrusion molding machine, and cut after water cooling to prepare a pellet-shaped molding material as an intermediate. And melting and mixing the stirred mixture under the conditions that the temperature of the charging barrel is 360-380 ℃, the temperature of the die is 380 ℃ and the temperature of a connecting pipe connecting the double-screw extrusion forming machine and the die is 380 ℃.

The molding material was dried in a dehumidifying dryer heated to 150 ℃ for 12 hours, and the dried molding material was melt-kneaded in a single-screw extrusion molding machine having a T die with a width of 900mm and a screw diameter of 40 mm. The molding material obtained by melt kneading was continuously extruded from a T die of a single-screw extrusion molding machine to form a film (thickness: 5 μm) for an insulating resin layer by tape-like extrusion molding.

A differential scanning calorimeter (manufactured by SII Nano Technology Co., Ltd.: the product name of the product is a high-sensitivity differential scanning calorimeter X-DSC7000 ], and the glass transition temperature of the film for an insulating resin layer is measured at a temperature rise rate of 10 ℃/min in accordance with JIS K7121. The same applies to the measurement of the glass transition temperature in the following examples and comparative examples. The glass transition temperature of the film for the insulating resin layer was 148 ℃.

The tensile modulus at 160 ℃ of the film for the insulating resin layer was measured for the extrusion direction and the width direction (direction perpendicular to the extrusion direction) of the film as described below. A test piece was cut out in accordance with JIS K71603, and the test piece was mounted on a jig of a tensile testing machine having a thermostatic bath heated to 160 ℃ in advance, the door of the thermostatic bath was closed, and after the temperature of the thermostatic bath reached 160 ℃. + -. 2 ℃, the test piece was left for 3 minutes, and then measured at a tensile rate of 50 mm/minute in accordance with JIS K7127. The results of the measurement are shown below.

Tensile modulus in the extrusion direction of the film: 1100N/mm²

Tensile modulus in the width direction of the film: 1046N/mm²

(production of electromagnetic wave-shielding film)

A carrier film was prepared, and a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive was provided on one surface of a PET film (carrier film main body). An insulating resin layer including the film for an insulating resin layer described above is bonded to the surface of the pressure-sensitive adhesive layer of the carrier film.

Next, copper was physically deposited by electron beam deposition on the surface of the insulating resin layer opposite to the carrier film to form a metal thin film layer (copper deposited film, thickness 0.07 μm, surface resistance 0.3 Ω).

A latent curable epoxy resin composition was obtained by mixing 100 parts by mass of a thermosetting adhesive (EXA-4816, produced by DIC) containing an epoxy resin and 20 parts by mass of a curing agent (Ajinomoto Fine-Technico., Inc., PN-23).

The latent curable epoxy resin composition and 40 parts by mass of conductive particles (average particle diameter 7.5 μm) including copper particles were dissolved or dispersed in 200 parts by mass of a solvent including methyl ethyl ketone to obtain a conductive adhesive coating material.

Next, the conductive adhesive coating was applied to the surface of the metal thin film layer opposite to the insulating resin layer using a die coater, and the solvent was evaporated to form a B-stage, thereby forming an anisotropic conductive adhesive layer (thickness 7 μm, copper particles 4.5 vol%).

A release film (T157, manufactured by Lintec Co.) was prepared in which a release agent layer (thickness: 0.1 μm) containing a non-silicone release agent was provided on one surface of a PET film (thickness: 50 μm).

The electromagnetic wave shielding film of example 1 was obtained by attaching the release film to the surface of the anisotropic conductive adhesive layer opposite to the metal thin film layer so that the release agent layer was in contact with the anisotropic conductive adhesive layer.

[ example 2]

PEEK (product name manufactured by Daicel Evonik Co., Ltd.): VESTAKEEP, category name: 3300G, PEI [ product name manufactured by SABIC: ULTEM: 1010-NB, glass transition temperature: 211 ℃ in a composition by mass ratio PEEK: 70 mass%, PEI: after 30 mass% was charged into a drum mixer, a stirred mixture was prepared in the same manner as in example 1, and an electromagnetic wave shielding film was produced. The glass transition temperature of the film for the insulating resin layer was 160 ℃. The tensile modulus at 160 ℃ of the film for an insulating resin layer is shown below.

Tensile modulus in the extrusion direction of the film: 2239N/mm²

Tensile modulus in the width direction of the film: 1661N/mm²

[ example 3]

PEEK (product name of Solvay Specialty Polymers Co.): ketarse polyetheretherketone brand name: KT-820NT ] and PEI used in example 2 were prepared in such a manner that PEEK: 50 mass%, PEI: after 50 mass% was charged into a drum mixer, a stirred mixture was prepared in the same manner as in example 1, and an electromagnetic wave shielding film was produced. The glass transition temperature of the film for the insulating resin layer was 174 ℃. The tensile modulus at 160 ℃ of the film for an insulating resin layer is shown below.

Tensile modulus in the extrusion direction of the film: 2331N/mm²

Tensile modulus in the width direction of the film: 2013N/mm²

[ example 4]

PEEK (product name of Victrex corporation: VictrexPEEK381G and PEI used in example 2 were mixed in the composition mass ratio of PEEK: 20 mass%, PEI: after 80 mass% was charged into a drum mixer, a stirred mixture was prepared in the same manner as in example 1 to produce an electromagnetic wave shielding film. The glass transition temperature of the film for the insulating resin layer was 198 ℃. The tensile modulus at 160 ℃ of the film for an insulating resin layer is shown below.

Tensile modulus in the extrusion direction of the film: 2720N/mm²

Tensile modulus in the width direction of the film: 2568N/mm²

[ example 5]

The PEEK and PEI used in example 1 were mixed in a composition mass ratio of PEEK: 10 mass%, PEI: after 90 mass% of the mixture was charged into a drum mixer, a stirred mixture was prepared in the same manner as in example 1, and an electromagnetic wave shielding film was produced. The glass transition temperature of the film for the insulating resin layer was 202 ℃. The tensile modulus at 160 ℃ of the film for an insulating resin layer is shown below.

Tensile modulus in the extrusion direction of the film: 2830N/mm²

Tensile modulus in the width direction of the film: 2660N/mm²

[ example 6]

An electromagnetic wave-shielding film of example 6 was obtained in the same manner as in example 2 except that PEKK (KEPSTAN 8002, a product name of ARKEMA) was used instead of PEEK. The glass transition temperature of the film for the insulating resin layer was 204 ℃. The tensile modulus at 160 ℃ of the film for an insulating resin layer is shown below.

Tensile modulus in the extrusion direction of the film: 2530N/mm²

Tensile modulus in the width direction of the film: 2439N/mm²

Comparative example 1

As a coating material for forming an insulating resin layer, 100 parts by mass of bisphenol a type epoxy resin (epichlone 840-S, manufactured by DIC corporation), 20 parts by mass of a curing agent (JER Cure 113, manufactured by mitsubishi chemical corporation), 2 parts by mass of 2-ethyl-4-methylimidazole and 2 parts by mass of carbon black were dissolved in 200 parts by mass of methyl ethyl ketone to prepare a coating material.

The above-described coating material for forming an insulating resin layer was applied to the surface of the adhesive layer of the same carrier film as used in example 1, dried by heating at 60 ℃ for 2 minutes, and semi-cured to form an insulating resin layer having a thickness of 5 μm. 1/m was observed on the insulating resin layer²Above and 3-m²The following pinholes.

A region having no pin hole was selected, and copper was physically deposited by electron beam deposition on the surface of the insulating resin layer in the selected region to form a metal thin film layer (copper deposited film, thickness 0.07 μm, surface resistance 0.3. omega.).

An anisotropic conductive adhesive layer was formed on the surface of the metal thin film layer opposite to the insulating resin layer, and a release film was attached to the anisotropic conductive adhesive layer, in the same manner as in example 1, to obtain an electromagnetic wave shielding film of comparative example 1.

[ evaluation ]

The adhesion between the insulating resin layer and the conductive layer of each electromagnetic wave-shielding film of each example was evaluated by the following method.

The electromagnetic wave shielding film after peeling the release film was laminated on a polyimide film having a thickness of 25 μm, and the film was heated and pressed by a hot press (G-12, manufactured by yokukoku corporation) at a hot plate temperature: 180 ℃ and load: hot pressing at 2MPa for 120 sec. Next, the carrier film was peeled off. Thus, an anisotropic conductive adhesive layer was temporarily adhered to the surface of the insulating film, thereby obtaining an electromagnetic wave shielding film-equipped polyimide.

The polyimide film with the electromagnetic wave shielding film was heated at 160 ℃ for 1 hour using a high-temperature bath (HT 210, manufactured by nanba technologies chemical corporation), and thereby the anisotropic conductive adhesive layer was main-cured.

Next, a polyimide reinforcing plate having a thickness of 25 μm was thermocompression bonded to the surface of the insulating resin layer of the electromagnetic wave shielding film via an adhesive sheet (D3410, manufactured by Dexerials corporation), thereby producing a test piece for a tensile test.

The polyimide film and the polyimide reinforcing plate of the test piece were fitted with a jig of a tensile tester, and a peel test was performed according to jis z0237 under conditions of a 180 ° peel direction and a tensile speed of 50 mm/min.

[ results ]

In the test piece using the electromagnetic wave-shielding film of example 1, the peel strength was 7.5N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of example 2, the peel strength was 7.2N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of example 3, the peel strength was 7.8N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of example 4, the peel strength was 7.3N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of example 5, the peel strength was 7.5N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of example 6, the peel strength was 5.3N/cm, and peeling occurred at the interface between the insulating resin layer and the metal thin film layer.

In the test piece using the electromagnetic wave-shielding film of comparative example 1, the peeling strength was 3.5N/cm, and interlayer peeling occurred between the insulating resin layer and the metal thin film layer.

From these results, it is understood that an insulating resin layer made of PEEK or PEKK, which is one kind of aromatic polyether ketone, and PEI has stronger adhesion to a metal thin film layer than an insulating resin layer made of a thermosetting resin that has been conventionally used.

In the insulating resin layers of examples 1 to 6, as the content of PEI increased relative to PEEK, the glass transition temperature of the insulating resin layer increased. As is clear from the results, the appearance of the insulating resin layer of the electromagnetic wave shielding film produced was smoother and better as the glass transition temperature increased. In the insulating resin layers of examples 1 and 2 having a glass transition temperature of 160 ℃ or lower, waviness was barely visually recognizable on the surfaces. This is caused by heat treatment (160 ℃) for main curing of the anisotropic conductive sheet. Such waviness, although not affecting peel strength, may impair appearance.

The films constituting the insulating resin layers of examples 1 to 6 all had good tensile modulus at 160 ℃, and were not easily affected by heat treatment during production or high-temperature environment during use. In particular, examples 3 to 5 in examples 1 to 6 are excellent in tensile modulus and also excellent in peel strength.

Description of the symbols

1 an electromagnetic wave-shielding film having a high dielectric constant,

2 a flexible printed wiring board with an electromagnetic wave shielding film,

3 a flexible printed wiring board with an insulating film,

10 an insulating resin layer, and an insulating resin layer,

22 a thin layer of a metal film,

20 of the electrically conductive layers, a conductive layer,

24 an anisotropic conductive adhesive layer comprising a mixture of a conductive resin,

24a of a thermosetting adhesive, and (c) a thermosetting adhesive,

24b of a conductive particle, and a conductive particle,

26 an isotropic conductive adhesive layer, wherein the isotropic conductive adhesive layer,

26a of a thermosetting adhesive, and (b) a thermosetting adhesive,

26b of a conductive material, and a conductive material,

30 a carrier film, and a carrier film,

32 a carrier film body, the carrier film body,

34 an adhesive layer, wherein the adhesive layer,

40, demoulding the film, namely removing the film,

42 the main body of the mold release film,

44 of a layer of a release agent,

50 a flexible printed wiring board to be mounted on a printed circuit board,

52 a base film, and a first adhesive layer,

54 the printed circuit board is printed with a printed circuit,

60 an insulating film is formed on the substrate,

62 through hole.

Claims

1. An electromagnetic wave shielding film having an insulating resin layer and a conductive layer containing a metal adjacent to the insulating resin layer,

the insulating resin layer contains aromatic polyether ketone and polyether imide.

2. The electromagnetic wave-shielding film according to claim 1, wherein the aromatic polyether ketone is polyether ether ketone or polyether ketone.

3. The electromagnetic wave shielding film according to claim 1 or 2, wherein the polyetherimide has a glass transition temperature of 200 ℃ or higher and has a repeating unit represented by the following chemical formula (a);

4. the electromagnetic wave-shielding film according to any one of claims 1 to 3, wherein a content of the aromatic polyether ketone is 5% by mass or more and 95% by mass or less, and a content of the polyether imide is 5% by mass or more and 95% by mass or less, with respect to a total mass of the insulating resin layers.

5. The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein the thickness of the insulating resin layer is 2 μm or more and 30 μm or less.

6. The electromagnetic wave-shielding film according to any one of claims 1 to 5, wherein the conductive layer is a metal vapor deposition layer.

7. The electromagnetic wave-shielding film according to claim 6, wherein the metal evaporation layer is a silver evaporation layer or a copper evaporation layer.

8. The electromagnetic wave shielding film according to any one of claims 1 to 7, further comprising a carrier film on a surface of the insulating resin layer opposite to the conductive layer.

9. A printed wiring board with an electromagnetic wave shielding film, comprising:

a printed wiring board having a printed circuit provided on at least one surface of a substrate;

an insulating film adjacent to a surface of the printed wiring board on which the printed circuit is provided; and the combination of (a) and (b),

the electromagnetic wave shielding film according to any one of claims 1 to 8, wherein the conductive layer is provided so as to be adjacent to the insulating film.

10. A method for manufacturing an electromagnetic wave shielding film, comprising the steps of: a mixed resin of aromatic polyether ketone and polyether imide is molded into a film shape to form an insulating resin layer, and a conductive layer is formed on one side of the insulating resin layer.

11. A method for manufacturing a printed wiring board with an electromagnetic wave shielding film, comprising the steps of: a printed wiring board having a printed circuit on at least one surface of a substrate, and the electromagnetic wave shielding film according to any one of claims 1 to 8, wherein the printed wiring board and the electromagnetic wave shielding film are pressure-bonded to each other through an insulating film.