JP2018166166A - Electromagnetic wave shield film and printed wiring board with electromagnetic wave shield film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shield film and a printed wiring board with an electromagnetic wave shield film, in which reflection of light on a surface of an insulating resin layer after a first release film has been peeled off is suppressed.SOLUTION: An electromagnetic wave shield film 1 includes an insulating resin layer 10, a conductive layer 20 adjacent to the insulating resin layer 10, and a first release film 30 adjacent to the insulating resin layer 10 on an opposite side to the conductive layer 20; the first release film 30 has an adhesive layer 34 in contact with the insulating resin layer 10; and the adhesive layer 34 includes an adhesive 34a and particles 34b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electromagnetic shielding film and a printed wiring board provided with the electromagnetic shielding film.

  In order to shield electromagnetic noise generated from a flexible printed wiring board and external electromagnetic noise, from an insulating resin layer and a conductive layer composed of a metal thin film layer and a conductive adhesive layer adjacent to the insulating resin layer The electromagnetic wave shielding film to be formed may be provided on the surface of the flexible printed wiring board via an insulating film (coverlay film) (see, for example, Patent Document 1).

  The electromagnetic wave shielding film is, for example, a coating liquid containing a thermosetting resin, a curing agent, and a solvent is applied to one side of a first release film that is a carrier film, and dried to form an insulating resin layer. It is manufactured by providing a conductive layer on the surface of the insulating resin layer.

  The first release film is peeled off from the insulating resin layer after the electromagnetic wave shielding film is attached to the surface of the insulating film provided on the surface of the flexible printed wiring board so that the conductive adhesive layer is in contact with the insulating film. Is done.

JP 2006-086120 A

However, the surface of the insulating resin layer after peeling off the first release film is smooth because the shape of the surface of the first release film is transferred, and has a high specular gloss. When the mirror glossiness of the surface of the insulating resin layer which is the outermost surface of the flexible printed wiring board with an electromagnetic wave shielding film is high, there are the following problems.
-When printing is performed on the surface of the insulating resin layer, the visibility of characters and designs printed by light reflection is deteriorated.
The optical sensor or the like may be affected by reflection of light from an insulating resin layer around the optical sensor (such as a CCD image sensor or a CMOS image sensor of a camera module).
・ Scratches on the surface of the insulating resin layer are easily noticeable.

  The present invention provides an electromagnetic wave shielding film and a printed wiring board with an electromagnetic wave shielding film in which reflection of light on the surface of an insulating resin layer after peeling off a first release film is suppressed.

The present invention has the following aspects.
<1> An insulating resin layer, a conductive layer adjacent to the insulating resin layer, and a first release film adjacent to the side of the insulating resin layer opposite to the conductive layer; An electromagnetic wave shielding film, wherein the mold film has an adhesive layer in contact with the insulating resin layer; and the adhesive layer contains an adhesive and particles.
<2> The electromagnetic wave shielding film according to <1>, wherein an average particle diameter of the particles is 0.5 μm or more and 15 μm or less.
<3> The electromagnetic wave shielding film according to <1> or <2>, wherein the particles are at least one selected from the group consisting of silica particles and acrylic particles.
<4> The electromagnetic wave shielding film according to any one of <1> to <3>, wherein the pressure-sensitive adhesive layer has a thickness of 0.5 μm to 10 μm.
<5> The electromagnetic wave shield according to any one of <1> to <4>, wherein the surface gloss of the insulating resin layer after peeling off the first release film is 0.5 or more and 40 or less. the film.
<6> The electromagnetic wave shield according to any one of <1> to <5>, wherein the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film is 0.2 μm or more and 2.5 μm or less. the film.
<7> Any one of <1> to <6>, wherein an average length RSm of a roughness curve element of the surface of the pressure-sensitive adhesive layer of the first release film is 0.01 mm or more and 0.1 mm or less. An electromagnetic shielding film.
<8> The electromagnetic wave shielding film according to any one of <1> to <7>, further including a second release film adjacent to the side of the conductive layer opposite to the insulating resin layer.
<9> a printed wiring board provided with a printed circuit on at least one side of the substrate; an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided; and the conductive layer adjacent to the insulating film And the electromagnetic wave shielding film according to any one of <1> to <7>, wherein the conductive layer is electrically connected to the printed circuit through a through-hole formed in the insulating film. Printed wiring board with shield film.

In the electromagnetic wave shielding film of the present invention, reflection of light on the surface of the insulating resin layer after the first release film is peeled off is suppressed.
In the printed wiring board with an electromagnetic wave shielding film of the present invention, light reflection on the surface of the insulating resin layer after the first release film is peeled off is suppressed.

It is sectional drawing which shows one Embodiment of the electromagnetic wave shield film of this invention. It is sectional drawing which shows other embodiment of the electromagnetic wave shielding film of this invention. It is sectional drawing which shows other embodiment of the electromagnetic wave shielding film of this invention. It is sectional drawing which shows the manufacturing process of the electromagnetic wave shielding film of FIG. It is sectional drawing which shows one Embodiment of the printed wiring board with an electromagnetic wave shield film of this invention. It is sectional drawing which shows the state which peeled the 1st release film from the printed wiring board with an electromagnetic wave shield film of FIG. It is sectional drawing which shows the manufacturing process of the printed wiring board with an electromagnetic wave shielding film of FIG. 5 and FIG.

The following definitions of terms apply throughout this specification and the claims.
The “isotropic conductive adhesive layer” means a conductive adhesive layer having conductivity in the thickness direction and the surface direction.
The “anisotropic conductive adhesive layer” means a conductive adhesive layer having conductivity in the thickness direction and not having conductivity in the surface direction.
The “conductive adhesive layer having no conductivity in the plane direction” means a conductive adhesive layer having a surface resistance of 1 × 10 ⁴ Ω or more.
Arithmetic mean roughness Ra is measured on a test piece with a laser microscope, and based on this roughness curve, JIS B 0601: 2013 (corresponding international standard ISO 4287: 1997, Amd. 1: 2009). This is the value obtained.
For the average length RSm of the roughness curve element, a roughness curve was measured for the test piece using a laser microscope, and from this roughness curve, JIS B 0601: 2013 (ISO 4287: 1997, Amd. 1: 2009) was measured. It is a value obtained based on this.
The specular glossiness is a value measured in accordance with JIS Z 8741: 1997 (corresponding international standard ISO 2813: 1994, ISO 7668: 1986) under the conditions of an incident angle / light receiving angle of 60 ° / 60 °.
For the average particle size of the particles, 30 particles are randomly selected from the microscopic image of the particles, the minimum and maximum diameters are measured for each particle, and the median of the minimum and maximum diameters is the particle size of one particle. This is a value obtained by arithmetically averaging the measured particle diameters of 30 particles. The same applies to the average particle size of the conductive particles.
The thickness of the film (release film, insulating film, etc.), coating film (insulating resin layer, conductive adhesive layer, etc.), metal thin film layer, etc. is observed at a cross section of the object to be measured using a microscope. Thickness was measured and averaged.
The storage elastic modulus is calculated as one of the viscoelastic characteristics using a dynamic viscoelasticity measuring device that is calculated from the stress applied to the measurement object and the detected strain and outputs it as a function of temperature or time.
The surface resistance is measured by using two thin film metal electrodes (length 10 mm, width 5 mm, distance 10 mm between electrodes) formed by depositing gold on quartz glass, placing an object to be measured on the electrodes, and measuring the surface resistance. This is a resistance between electrodes measured by pressing a 10 mm × 20 mm region of the object to be measured with a load of 0.049 N from above the object with a measurement current of 1 mA or less.
The dimensional ratios in FIGS. 1 to 7 are different from actual ones for convenience of explanation.

<Electromagnetic wave shielding film>
FIG. 1 is a cross-sectional view showing a first embodiment of the 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, and FIG. It is sectional drawing which shows 3rd Embodiment of the electromagnetic wave shield film of this invention.
The electromagnetic wave shielding film 1 of the first embodiment, the second embodiment, and the third embodiment includes an insulating resin layer 10; a conductive layer 20 adjacent to the insulating resin layer 10; and a conductive layer 20 of the insulating resin layer 10. A first release film 30 adjacent to the opposite side of the conductive layer 20; and a second release film 40 adjacent to the side of the conductive layer 20 opposite to the insulating resin layer 10.

In the electromagnetic wave shielding film 1 of the first embodiment, the conductive layer 20 includes a metal thin film layer 22 adjacent to the insulating resin layer 10 and an anisotropic conductive adhesive layer 24 adjacent to the second release film 40. This is an example.
In the electromagnetic wave shielding film 1 of the second embodiment, the conductive layer 20 includes a metal thin film layer 22 adjacent to the insulating resin layer 10 and an isotropic conductive adhesive layer 26 adjacent to the second release film 40. This is an example.
The electromagnetic wave shielding film 1 of the third embodiment is an example in which the conductive layer 20 is composed only of the isotropic conductive adhesive layer 26.

(Insulating resin layer)
The insulating resin layer 10 serves as a base (base) for forming the metal thin film layer 22. Moreover, after the insulating resin layer 10 has adhered the electromagnetic wave shielding film 1 to the surface of the insulating film provided on the surface of the flexible printed wiring board and peeled off the first release film 30, the metal thin film layer 22 It becomes a protective layer.

  As the insulating resin layer 10, a coating film formed by applying and semi-curing or curing a paint containing a thermosetting resin and a curing agent; a coating film formed by applying a paint containing a thermoplastic resin; Examples thereof include a layer made of a film obtained by melt-molding a composition containing a thermoplastic resin. From the viewpoint of heat resistance during soldering or the like, a coating film formed by applying a paint containing a thermosetting resin and a curing agent and semi-curing or curing is preferable.

Examples of the thermosetting resin include amide resin, epoxy resin, phenol resin, amino resin, alkyd resin, urethane resin, synthetic rubber, and ultraviolet curable acrylate resin. As the thermosetting resin, an amide resin and an epoxy resin are preferable from the viewpoint of excellent heat resistance.
As a hardening | curing agent, the well-known hardening | curing agent according to the kind of thermosetting resin is mentioned.

The insulating resin layer 10 is either one of a colorant (pigment, dye, etc.) and a filler or the like in order to conceal the printed circuit of the printed wiring board or to give design properties to the printed wiring board with an electromagnetic wave shielding film. Both may be included.
As one or both of the colorant and the filler, a pigment or a filler is preferable from the viewpoint of weather resistance, heat resistance, and concealment. From the viewpoint of concealment and design of the printed circuit, a black pigment or a black pigment is used. Combinations with other pigments or fillers are more preferred.

The insulating resin layer 10 may contain a flame retardant.
The insulating resin layer 10 may contain other components as necessary within a range not impairing the effects of the present invention.

Since the surface of the insulating resin layer 10 has unevenness formed by transferring the unevenness of the surface of the pressure-sensitive adhesive layer 34 of the first release film 30, the specular glossiness of the surface can be kept low.
The mirror glossiness of the surface of the insulating resin layer 10 after peeling the first release film 30 is preferably 0.5 or more and 40 or less, more preferably 1 or more and 30 or less, and further preferably 5 or more and 20 or less. If the mirror glossiness of the surface of the insulating resin layer 10 is equal to or higher than the lower limit of the above range, the pressure-sensitive adhesive layer 34 can be produced with an added amount of particles 34b that does not impair the performance of the pressure-sensitive adhesive 34a. When the specular gloss of the surface of the insulating resin layer 10 is not more than the upper limit of the above range, the reflection of light on the surface of the insulating resin layer 10 after the first release film 30 is peeled is sufficiently suppressed.

The storage elastic modulus at 180 ° C. of the insulating resin layer 10 is preferably 5 × 10 ⁶ Pa to 5 × 10 ⁹ Pa, and more preferably 1 × 10 ⁷ Pa to 1 × 10 ⁹ Pa. If the storage elastic modulus at 180 ° C. of the insulating resin layer 10 is equal to or higher than the lower limit of the above range, the insulating resin layer 10 has an appropriate hardness, and the pressure loss in the insulating resin layer 10 during hot pressing is reduced. Can be reduced. As a result, the conductive adhesive layer and the printed circuit of the printed wiring board are sufficiently bonded, and the conductive adhesive layer is securely electrically connected by the printed circuit of the printed wiring board through the through hole of the insulating film. The If the storage elastic modulus at 180 ° C. of the insulating resin layer 10 is equal to or less than the upper limit of the above range, the flexibility of the electromagnetic wave shielding film 1 is improved. As a result, the electromagnetic wave shielding film 1 easily sinks into the through hole of the insulating film, and the conductive adhesive layer is reliably electrically connected by the printed circuit of the printed wiring board through the through hole of the insulating film.

The surface resistance of the insulating resin layer 10 is preferably 1 × 10 ⁶ Ω or more from the viewpoint of electrical insulation. The surface resistance of the insulating resin layer 10 is preferably 1 × 10 ¹⁹ Ω or less from a practical point of view.
The thickness of the insulating resin layer 10 is preferably 0.1 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 20 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 exhibit the 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 thinned.

(Conductive layer)
As the conductive layer 20, a metal thin film layer 22 adjacent to the insulating resin layer 10 and a conductive adhesive layer (an anisotropic conductive adhesive layer 24) that is the outermost layer on the opposite side of the conductive layer 20 from the insulating resin layer 10. Alternatively, a conductive layer (I) having an isotropic conductive adhesive layer 26); or a conductive layer (II) consisting only of the isotropic conductive adhesive layer 26 may be mentioned. As the conductive layer 20, the conductive layer (I) is preferable because it can sufficiently function as an electromagnetic wave shielding layer.

(Metal thin film layer)
The metal thin film layer 22 is a layer made of a metal thin film. Since the metal thin film layer 22 is formed so as to spread in the surface direction, it has conductivity in the surface 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, etc.) or CVD, a plating film formed by plating, a metal foil, and the like. From the point of excellent surface direction conductivity, a vapor deposition film and a plating film are preferable, the thickness can be reduced, and even if the thickness is small, the surface direction conductivity is excellent and can be easily formed by a dry process. A vapor deposition film is more preferable, and a vapor deposition film formed by physical vapor deposition is more preferable.

  Examples of the metal constituting the metal thin film layer 22 include aluminum, silver, copper, gold, and conductive ceramics. From the viewpoint of electrical conductivity, copper is preferable, and from the viewpoint of chemical stability, conductive ceramics are preferable.

  The surface resistance of the metal thin film layer 22 is preferably 0.001Ω to 1Ω, and more preferably 0.001Ω to 0.5Ω. 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 made sufficiently thin. If the surface resistance of the metal thin film layer 22 is less than or equal to the upper limit of the above range, the metal thin film layer 22 can sufficiently function as an electromagnetic wave shielding layer.

  The thickness of the metal thin film layer 22 is preferably 0.01 μm or more and 1 μm or less, and more preferably 0.05 μm or more and 1 μm or less. When the thickness of the metal thin film layer 22 is 0.01 μm or more, the surface conductivity 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 equal to or less than the upper limit of the above range, the electromagnetic wave shielding film 1 can be thinned. Further, the productivity and flexibility of the electromagnetic wave shielding film 1 are improved.

(Conductive adhesive layer)
The conductive adhesive layer has conductivity at least in the thickness direction and has adhesiveness.
As the conductive adhesive layer, an anisotropic conductive adhesive layer 24 having conductivity in the thickness direction and having no conductivity in the surface direction, or having conductivity in the thickness direction and the surface direction, etc. An electrically conductive adhesive layer 26 is exemplified. As the conductive adhesive layer in the conductive layer (I), the conductive adhesive layer can be made thin and the amount of conductive particles can be reduced. As a result, the electromagnetic wave shielding film 1 can be made thin, and the electromagnetic wave shielding film 1 is flexible. From the viewpoint of improving the properties, the anisotropic conductive adhesive layer 24 is preferable. As the conductive adhesive layer in the conductive layer (I), the isotropic conductive adhesive layer 26 is preferable in that it can sufficiently function as an electromagnetic wave shielding layer.

As the conductive adhesive layer, a thermosetting conductive adhesive layer is preferable because heat resistance can be exhibited after curing. The thermosetting conductive adhesive layer may be in an uncured state or in a B-staged state.
The thermosetting anisotropic conductive adhesive layer 24 includes, for example, a thermosetting adhesive 24a and conductive particles 24b.
The thermosetting isotropic conductive adhesive layer 26 includes, for example, a thermosetting adhesive 26a and conductive particles 26b.

As a thermosetting adhesive, what contains the thermosetting resin and adhesive which have adhesiveness is mentioned.
Examples of the thermosetting resin include an epoxy resin, a phenol resin, an amino resin, an alkyd resin, a urethane resin, a synthetic rubber, and an ultraviolet curable acrylate resin. As the thermosetting resin, an epoxy resin is preferable from the viewpoint of excellent heat resistance.
As a hardening | curing agent, the well-known hardening | curing agent according to the kind of thermosetting resin is mentioned.

When the thermosetting resin is an epoxy resin, the thermosetting adhesive may contain a rubber component (carboxy-modified nitrile rubber, acrylic rubber, etc.) for imparting flexibility, a tackifier, and the like.
The thermosetting adhesive may contain a flame retardant as necessary.
The thermosetting adhesive may contain a cellulose resin and microfibrils (such as glass fibers) in order to increase the strength of the conductive adhesive layer and improve the punching characteristics.
The thermosetting adhesive may contain other components as necessary within a range not impairing the effects of the present invention.

  Examples of the conductive particles include metal (silver, platinum, gold, copper, nickel, palladium, aluminum, solder, etc.) particles, graphite powder, calcined carbon particles, plated calcined carbon particles, and the like. As the conductive particles, metal particles are preferable and copper particles are preferable from the viewpoint that the conductive adhesive layer has an appropriate hardness and can reduce pressure loss in the conductive adhesive layer during hot pressing. More preferred.

  The average particle diameter of the conductive particles 24b in the anisotropic conductive adhesive layer 24 is preferably 2 μm to 26 μm, and more preferably 4 μm to 16 μm. If the average particle diameter of the conductive particles 24b is equal to or greater than the lower limit of the above range, the thickness of the anisotropic conductive adhesive layer 24 can be ensured, and sufficient adhesive strength can be obtained. If the average particle diameter of the conductive particles 24b is equal to or less than the upper limit of the above range, the fluidity of the anisotropic conductive adhesive layer 24 (followability to the shape of the through holes of the insulating film) can be secured, and the insulating film The inside of the through hole can be sufficiently filled with a conductive adhesive.

  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. When the average particle diameter of the conductive particles 26b is equal to or greater 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 increased. If the average particle diameter of the conductive particles 26b is less than or equal to the upper limit of the above range, the fluidity of the isotropic conductive adhesive layer 26 (followability to the shape of the through holes of the insulating film) can be secured, and the insulating film The inside of the through hole can be sufficiently filled with a conductive adhesive.

  The proportion of the conductive particles 24b in the anisotropic conductive adhesive layer 24 is preferably 1% by volume to 30% by volume, and preferably 2% by volume to 10% by volume, out of 100% by volume of the anisotropic conductive adhesive layer 24. The following is more preferable. When the ratio of the conductive particles 24b is equal to or higher than the lower limit of the above range, the conductivity of the anisotropic conductive adhesive layer 24 is improved. When the ratio of the conductive particles 24b is equal to or less than the upper limit of the above range, the adhesiveness and fluidity (followability to the shape of the through hole of the insulating film) of the anisotropic conductive adhesive layer 24 are improved. Moreover, the flexibility of the electromagnetic wave shielding film 1 is improved.

  The proportion of the conductive particles 26b in the isotropic conductive adhesive layer 26 is preferably 50% by volume or more and 80% by volume or less in 100% by volume of the isotropic conductive adhesive layer 26, and 60% by volume or more and 70% by volume. The following is more preferable. When the ratio of the conductive particles 26b is equal to or higher than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 26 is improved. When the ratio of the conductive particles 26b is equal to or less than the upper limit of the above range, the adhesiveness and fluidity of the isotropic conductive adhesive layer 26 (followability to the shape of the through hole of the insulating film) are improved. Moreover, the flexibility of the electromagnetic wave shielding film 1 is improved.

The storage elastic modulus at 180 ° C. of the conductive adhesive layer is preferably 1 × 10 ³ Pa or more and 5 × 10 ⁷ Pa or less, and more preferably 5 × 10 ³ Pa or more and 1 × 10 ⁷ Pa or less. If the storage elastic modulus at 180 ° C. of the conductive adhesive layer is equal to or higher than the lower limit of the above range, the conductive adhesive layer has a further appropriate hardness, and the conductive adhesive layer during hot pressing. The pressure loss at can be reduced. As a result, the conductive adhesive layer and the printed circuit of the printed wiring board are sufficiently bonded, and the conductive adhesive layer is securely electrically connected by the printed circuit of the printed wiring board through the through hole of the insulating film. The If the storage elastic modulus at 180 ° C. of the conductive adhesive layer is not more than the upper limit of the above range, the flexibility of the electromagnetic wave shielding film 1 is improved. As a result, the electromagnetic wave shielding film 1 easily sinks into the through hole of the insulating film, and the conductive adhesive layer is reliably electrically connected by the printed circuit of the printed wiring board through the through hole of the insulating film.

The surface resistance of the anisotropic conductive adhesive layer 24 is preferably 1 × 10 ⁴ Ω to 1 × 10 ¹⁶ Ω, more preferably 1 × 10 ⁶ Ω to 1 × 10 ¹⁴ Ω. 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 kept 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 anisotropy in practice.

  The surface resistance of the isotropic conductive adhesive layer 26 is preferably 0.05Ω to 2.0Ω, more preferably 0.1Ω to 1.0Ω. If the surface resistance of the isotropic conductive adhesive layer 26 is equal to or greater than the lower limit of the above range, the content of the conductive particles 26b can be kept low, the viscosity of the conductive adhesive does not become too high, and the coatability is further increased. It becomes good. Further, the fluidity of the isotropic conductive adhesive layer 26 (followability 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 less than or equal to the upper limit of the above range, the entire surface of the isotropic conductive adhesive layer 26 has uniform conductivity.

  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 equal to or greater than the lower limit of the above range, the fluidity of the anisotropic conductive adhesive layer 24 (followability to the shape of the through hole of the insulating film) can be secured, 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 equal to or less than the upper limit of the above range, the electromagnetic wave shielding film 1 can be thinned. Moreover, the flexibility of the electromagnetic wave shielding film 1 is improved.

  The thickness of the 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 equal to or greater than the lower limit of the above range, the conductivity of the isotropic conductive adhesive layer 26 becomes good and can sufficiently function as an electromagnetic wave shielding layer. Further, the fluidity of the isotropic conductive adhesive layer 26 (followability to the shape of the through hole of the insulating film) can be ensured, and the through hole of the insulating film can be sufficiently filled with the conductive adhesive. The bendability can be secured and the isotropic conductive adhesive layer 26 will not be torn even if it is repeatedly bent. If the thickness of the isotropic conductive adhesive layer 26 is equal to or less than the upper limit of the above range, the electromagnetic wave shielding film 1 can be thinned. Moreover, the flexibility of the electromagnetic wave shielding film 1 is improved.

(First release film)
The first release film 30 serves as a carrier film for the insulating resin layer 10 and the conductive layer 20 and improves the handling properties of the electromagnetic wave shielding film 1. The first release film 30 is peeled from the insulating resin layer 10 after the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like.

  The first release film 30 includes a release film body 32 and an adhesive layer 34 provided on the surface of the release film body 32 on the insulating resin layer 10 side.

  As the resin material of the release film body 32, polyethylene terephthalate (hereinafter also referred to as PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, ethylene-vinyl acetate. Examples thereof include a copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, and a liquid crystal polymer. As the resin material, PET is preferable from the viewpoint of heat resistance (dimensional stability) and price when the electromagnetic wave shielding film 1 is manufactured.

The release film body 32 may contain one or both of a colorant (pigment, dye, etc.) and a filler.
Either one or both of the colorant and the filler is different from the insulating resin layer 10 in that it can be clearly distinguished from the insulating resin layer 10 and is easily noticed after the first release film 30 is peeled off after hot pressing. Colored ones are preferred, and white pigments, fillers, or combinations of white pigments with other pigments or fillers are more preferred.

  When the pressure-sensitive adhesive layer 34 is sufficiently white or the like due to particles contained in the pressure-sensitive adhesive layer 34, the release film main body 32 may be transparent without containing a colorant and a filler. If the release film body 32 does not contain a colorant and a filler, the first release film 30 can be manufactured at low cost.

The storage elastic modulus of the release film body 32 at 180 ° C. is preferably 8 × 10 ⁷ Pa or more and 5 × 10 ⁹ Pa, more preferably 1 × 10 ⁸ Pa or more and 8 × 10 ⁸ Pa. If the storage elastic modulus at 180 ° C. of the release film body 32 is equal to or higher than the lower limit of the above range, the first release film 30 has an appropriate hardness, and the first release at the time of hot pressing. The pressure loss in the mold film 30 can be reduced. If the storage elastic modulus at 180 ° C. of the release film main body 32 is equal to or less than the upper limit of the above range, the flexibility of the first release film 30 is good.

  The thickness of the release 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 release film main body 32 is not less than the lower limit of the above range, the handling property of the electromagnetic wave shielding film 1 will be good. If the thickness of the release film main body 32 is equal to or less than the upper limit of the above range, heat is easily transmitted to the conductive adhesive layer when the conductive adhesive layer of the electromagnetic wave shielding film 1 is hot-pressed on the surface of the insulating film. .

The pressure-sensitive adhesive layer 34 includes a pressure-sensitive adhesive 34a and particles 34b.
The pressure-sensitive adhesive layer 34 is formed, for example, by applying a pressure-sensitive adhesive composition including a pressure-sensitive adhesive 34 a and particles 34 b to the surface of the release film main body 32. When the first release film 30 has the pressure-sensitive adhesive layer 34, the second release film 40 is peeled from the conductive adhesive layer, or the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like by hot pressing. In this case, the first release film 30 can be prevented from peeling from the insulating resin layer 10, and the first release film 30 can sufficiently serve as a protective film.

The pressure-sensitive adhesive 34a is such that the first release film 30 is not easily peeled off from the insulating resin layer 10 before hot pressing, and the first release film 30 can be peeled off from the insulating resin layer 10 after hot pressing. In addition to imparting appropriate adhesiveness to the pressure-sensitive adhesive layer 34, the particles 34b are prevented from falling off the pressure-sensitive adhesive layer 34.
Examples of the adhesive 34a include acrylic adhesives, urethane adhesives, rubber adhesives, and the like.
The glass transition temperature of the adhesive 34a is preferably −100 to 60 ° C., and more preferably −60 to 40 ° C.

The particles 34 b give unevenness to the surface of the pressure-sensitive adhesive layer 34.
Examples of the particles 34b include inorganic particles and polymer particles. Examples of the inorganic particles include silica particles, calcium carbonate particles, titanium oxide particles, and alumina particles. Examples of the polymer particles include acrylic particles and melamine particles. As the particles 34b, at least one selected from the group consisting of silica particles and acrylic particles is preferable from the viewpoint of being easily adapted to the adhesive 34a and producing uniform unevenness.
As the particles 34b, one type may be used alone, or two or more types may be used in combination.

  The average particle diameter of the particles 34b is preferably 0.5 μm or more and 15 μm or less, more preferably 1 μm or more and 13 μm or less, and further preferably 2 μm or more and 10 μm or less. If the average particle diameter of the particles 34b is equal to or greater than the lower limit of the above range, the film thickness of the pressure-sensitive adhesive 34a is approximately the same, so that the unevenness of the particles 34b can be prevented from being buried in the pressure-sensitive adhesive layer 34. If the average particle diameter of the particles 34b is not more than the upper limit of the above range, the particles 34b will not be detached from the pressure-sensitive adhesive layer 34.

  The addition amount of the particles 34b is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the solid content of the adhesive 34a. If the addition amount of the particles 34 b is equal to or greater than the lower limit of the above range, the unevenness on the surface of the pressure-sensitive adhesive layer 34 of the first release film 30 is sufficiently transferred to the surface of the insulating resin layer 10. As a result, the reflection of light on the surface of the insulating resin layer 10 after peeling the first release film 30 is sufficiently suppressed. If the addition amount of the particles 34b is not more than the upper limit of the above range, the particles 34b do not inhibit the adhesiveness of the adhesive 34a, and the adhesive layer 34 has appropriate adhesiveness.

  The thickness of the pressure-sensitive adhesive layer 34 is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 8 μm or less, and further preferably 2 μm or more and 5 μm or less. If the thickness of the pressure-sensitive adhesive layer 34 is equal to or greater than the lower limit of the above range, the particles 34b can be prevented from being detached from the pressure-sensitive adhesive layer 34, and the adhesive force required for workability can be maintained. If the thickness of the pressure-sensitive adhesive layer 34 is not more than the upper limit of the above range, the particles 34b are not buried in the pressure-sensitive adhesive 34a, and uniform unevenness can be obtained, and a lightly peelable pressure-sensitive adhesive layer 34 can be obtained.

  The arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer 34 is preferably 0.2 μm or more and 2.5 μm or less, more preferably 0.3 μm or more and 2.5 μm or less, further preferably 0.4 μm or more and 2 μm or less, and 0.5 μm. The thickness is particularly preferably 1.5 μm or less. If the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer 34 is equal to or greater than the lower limit of the above range, the unevenness of the surface of the pressure-sensitive adhesive layer 34 of the first release film 30 is sufficiently transferred to the surface of the insulating resin layer 10. Is done. As a result, the reflection of light on the surface of the insulating resin layer 10 after peeling the first release film 30 is sufficiently suppressed. If the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer 34 is not more than the upper limit of the above range, the adhesion between the first release film 30 and the insulating resin layer 10 does not become too high, and the first release The film 30 is easily peeled from the insulating resin layer 10. In addition, when the adjacent insulating resin layers 10 are formed by applying an insulating resin layer forming paint, a smooth insulating resin layer 10 can be obtained without causing pinholes or the like.

  The average length RSm of the roughness curve element on the surface of the pressure-sensitive adhesive layer 34 is preferably 0.01 mm or more and 0.1 mm or less, and more preferably 0.02 mm or more and 0.07 mm or less. If the average length RSm of the roughness curve element on the surface of the pressure-sensitive adhesive layer 34 is not less than the lower limit of the above range, the adhesion between the first release film 30 and the insulating resin layer 10 does not become too high, and the first One release film 30 is easily peeled from the insulating resin layer 10. If the average length RSm of the roughness curve element on the surface of the pressure-sensitive adhesive layer 34 is less than or equal to the upper limit of the above range, the unevenness on the surface of the pressure-sensitive adhesive layer 34 of the first release film 30 is the surface of the insulating resin layer 10. Is fully transcribed. As a result, the reflection of light on the surface of the insulating resin layer 10 after peeling the first release film 30 is sufficiently suppressed.

  The thickness of the first release 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 1st release film 30 is more than the lower limit of the said range, the handleability of the electromagnetic wave shielding film 1 will become favorable. If the thickness of the first release film 30 is equal to or less than the upper limit of the above range, heat is applied to the conductive adhesive layer when the conductive adhesive layer of the electromagnetic wave shielding film 1 is hot-pressed on the surface of the insulating film. Easy to communicate.

(Second release film)
The second release film 40 protects the conductive adhesive layer and improves the handling properties of the electromagnetic wave shielding film 1. The second release film 40 is peeled from the conductive adhesive layer before the electromagnetic wave shielding film 1 is attached to a printed wiring board or the like.

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

Examples of the resin material for the release film main body 42 include the same resin materials as those for the release film main body 32.
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 release agent layer 44 is formed by treating the surface of the release film main body 42 with a release agent. When the second release film 40 has the release agent layer 44, the second release film 40 can be easily peeled off when the second release film 40 is peeled off from the conductive adhesive layer. The adhesive layer becomes difficult 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. When the thickness of the release agent layer 44 is within the above range, the second release film 40 is further easily peeled off.

(Thickness of electromagnetic shielding film)
The thickness of the electromagnetic shielding film 1 (excluding the release film) is preferably 5 μm or more and 50 μm or less, and more preferably 8 μm or more and 30 μm or less. When the thickness of the electromagnetic wave shielding film 1 (excluding the release film) is equal to or greater than the lower limit of the above range, it is difficult to break when the first release film 30 is peeled off. If the thickness of the electromagnetic wave shielding film 1 (excluding the release film) 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 shielding film)
The electromagnetic wave shielding film of this invention can be manufactured by the method ((alpha)) which has the following process (a)-(c), for example.
Step (a): A step of forming an insulating resin layer on one side of the first release film.
Step (b): A step of forming a conductive layer on the surface of the insulating resin layer after the step (a).
Step (c): A step of attaching a second release film to the surface of the conductive layer after the step (b).

Moreover, the electromagnetic wave shielding film of this invention can be manufactured by the method ((beta)) which has the following process (a '), (b'1), (b'2), (c'), for example.
Step (a ′): a step of forming an insulating resin layer on one side of the first release film.
Step (b′1): By forming a metal thin film layer on the surface of the insulating resin layer, a first laminate including a first release film, an insulating resin layer, and a metal thin film layer in order is obtained. Process.
Step (b′2): a second laminate comprising a second release film and a conductive adhesive layer in this order by forming a conductive adhesive layer on one side of the second release film. Obtaining.
Step (c ′): A step of bonding the first laminate and the second laminate so that the metal thin film layer and the conductive adhesive layer are in contact with each other.

  Hereinafter, a method for producing the electromagnetic wave shielding film 1 shown in FIG. 1 by the method (α) will be described with reference to FIG.

Step (a):
As shown in FIG. 4, the insulating resin layer 10 is formed on the surface of the pressure-sensitive adhesive layer 34 of the first release film 30.
The first release film 30 is manufactured, for example, by applying an adhesive composition including an adhesive 34 a and particles 34 b to the surface of the release film main body 32 to form the adhesive layer 34.
As a method for forming the insulating resin layer 10, from the viewpoint of heat resistance during reflow soldering, an insulating resin layer-forming paint containing a thermosetting resin and a curing agent is applied and semi-cured or cured. The method is preferred.
The coating for forming the insulating resin layer may contain a solvent, a colorant, a filler, a flame retardant, or other components as necessary.

Step (b):
As shown in FIG. 4, a metal thin film layer 22 is formed on the surface of the insulating resin layer 10 (step (b1)), and an anisotropic conductive adhesive layer 24 is formed on the surface of the metal thin film layer 22 (step (b2). )).

  Examples of the method for forming the metal thin film layer 22 include physical vapor deposition, a method of forming a vapor deposition film by CVD, a method of forming a plating film by plating, and a method of attaching a metal foil. From the viewpoint that the metal thin film layer 22 having excellent surface conductivity can be formed, a method of forming a vapor deposition film by physical vapor deposition, CVD, or a method of forming a plating film by plating is preferable, and the thickness of the metal thin film layer 22 is reduced. The metal thin film layer 22 having excellent conductivity in the plane direction can be formed even when the thickness is small, and the metal thin film layer 22 can be easily formed by a dry process. Therefore, the vapor deposition film is formed by physical vapor deposition or CVD. A method is more preferable, and a method of forming a deposited film by physical vapor deposition is further preferable.

Examples of the method for forming the anisotropic conductive adhesive layer 24 include a method of applying a thermosetting conductive adhesive composition to the surface of the metal thin film layer 22.
As a thermosetting conductive adhesive composition, what contains the thermosetting adhesive 24a and the electroconductive particle 24b is used.

Step (c):
As shown in FIG. 4, the second release film 40 is attached to the surface of the anisotropic conductive adhesive layer 24 to obtain the electromagnetic wave shielding film 1.

(Function and effect)
In the electromagnetic wave shielding film 1 described above, the first release film 30 has the adhesive layer 34 in contact with the insulating resin layer 10, and the adhesive layer 34 includes the adhesive 34 a and the particles 34 b. Therefore, the insulating resin layer 10 has irregularities formed by transferring irregularities on the surface of the pressure-sensitive adhesive layer 34. Therefore, the specular glossiness of the surface of the insulating resin layer 10 after the first release film 30 is peeled can be kept low. As a result, the reflection of light on the surface of the insulating resin layer 10 after peeling the first release film 30 is suppressed. And the following advantage is acquired by the reflection of the light in the surface of the insulating resin layer 10 being suppressed.
-When printing is performed on the surface of the insulating resin layer 10, the visibility of characters and pictures is good.
-Reflection of light from the insulating resin layer 10 is suppressed in the vicinity of the optical sensor or the like, and the optical sensor or the like is not easily affected by the reflection of light.
・ Scratches on the surface of the insulating resin layer are not noticeable.

(Other embodiments)
The electromagnetic wave shielding film of the present invention has an insulating resin layer, a conductive layer adjacent to the insulating resin layer, and a first release film adjacent to the side opposite to the conductive layer of the insulating resin layer; The release film has an adhesive layer in contact with the insulating resin layer; the adhesive layer only needs to contain an adhesive and particles, and is not limited to the illustrated embodiment.
For example, the second release film may have a pressure-sensitive adhesive layer instead of the release agent layer when the tackiness of the surface of the conductive adhesive layer is small. Alternatively, the second release film may be omitted.
When the mold release property of the release film main body is high, the second release film may be composed of only the release film main body without the release agent layer.
Two or more insulating resin layers may be used.

<Printed wiring board with electromagnetic shielding film>
FIG. 5 is a cross-sectional view showing an embodiment of a printed wiring board with an electromagnetic wave shielding film of the present invention.
The flexible printed wiring board 2 with an electromagnetic wave shielding film 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 has a printed circuit 54 provided on at least one side 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 flexible printed wiring board 2 with an electromagnetic wave shielding film, the second release film 40 is peeled from the anisotropic conductive adhesive layer 24.

  When the first release film 30 is no longer necessary in the flexible printed wiring board 2 with the electromagnetic wave shielding film, the first release film 30 is peeled from the insulating resin layer 10 as shown in FIG. . After the first release film 30 is peeled, the unevenness formed by transferring the unevenness of the surface of the pressure-sensitive adhesive layer 34 of the first release film 30 to the surface of the insulating resin layer 10 is exposed.

In the vicinity of the printed circuit 54 (signal circuit, ground circuit, ground layer, etc.) excluding the portion having the through hole, the metal thin film layer 22 of the electromagnetic wave shielding film 1 is provided with the insulating film 60 and the anisotropic conductive adhesive layer 24. Are arranged opposite to each other.
The separation distance between the printed circuit 54 and the metal thin film layer 22 excluding 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. When the separation distance is smaller than 30 μm, the impedance of the signal circuit is lowered. Therefore, in order to have a characteristic impedance such as 100Ω, the line width of the signal circuit has to be reduced, and the variation in the line width causes the variation in the characteristic impedance. Thus, the reflection resonance noise due to the impedance mismatch is easily applied to the electric signal. When the separation distance is larger than 200 μm, the flexible printed wiring board 2 with the electromagnetic wave shielding film becomes thick and the flexibility is insufficient.

(Flexible printed wiring board)
The flexible printed wiring board 50 is a printed circuit (a power circuit, a ground circuit, a ground layer, etc.) formed by processing a copper foil of a copper clad laminate into a desired pattern by a known etching method.
As the copper-clad laminate, one or both surfaces of the base film 52 are bonded with copper foil via an adhesive layer (not shown); a resin solution or the like that forms the base film 52 is cast on the surface of the copper foil And the like.
Examples of the material for the adhesive layer include epoxy resin, polyester, polyimide, polyamideimide, polyamide, phenol resin, urethane resin, acrylic resin, and melamine resin.
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 heat resistant film, more preferably a polyimide film or a liquid crystal polymer film, and even more preferably a polyimide film.
The surface resistance of the base film 52 is preferably 1 × 10 ⁶ Ω or more from the viewpoint of electrical insulation. The surface resistance of the base film 52 is preferably 1 × 10 ¹⁹ Ω or less from a practical point of view.
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 25 μm or less, and 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 (signal circuit, ground circuit, ground layer, etc.) include rolled copper foil, electrolytic copper foil, and the like, and rolled copper foil is preferred from the viewpoint of flexibility.
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.
An end (terminal) in the length direction of the printed circuit 54 is not covered with the insulating film 60 or the electromagnetic wave shielding film 1 for solder connection, connector connection, component mounting, or the like.

(Insulating film)
The insulating film 60 (coverlay film) is obtained by forming an adhesive layer (not shown) on one surface of an insulating film main body (not shown) by applying an adhesive, attaching an adhesive sheet, or the like.
The surface resistance of the insulating film body is preferably 1 × 10 ⁶ Ω or more from the viewpoint of electrical insulation. The surface resistance of the insulating film body is preferably 1 × 10 ¹⁹ Ω or less from a practical point of view.
As an insulating film main body, the film which has heat resistance is preferable, a polyimide film and a liquid crystal polymer film are more preferable, and a polyimide film is further more preferable.
The thickness of the insulating film body is preferably 1 μm to 100 μm, and more preferably 3 μm to 25 μm from the viewpoint of flexibility.
Examples of the material for the adhesive layer include epoxy resin, polyester, polyimide, polyamideimide, polyamide, phenol resin, urethane resin, acrylic resin, melamine resin, polystyrene, and polyolefin. The epoxy resin may contain a rubber component (carboxy-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 is not particularly limited. Examples of the shape of the opening of the through hole 62 include a circle, an ellipse, and a quadrangle.

(Method for producing printed wiring board with electromagnetic shielding film)
The printed wiring board with an electromagnetic wave shielding film of the present invention can be produced by, for example, a method having the following steps (d) to (g).
Step (d): A step of obtaining a printed wiring board with an insulating film by providing an insulating film having through holes formed at positions corresponding to the printed circuit on the surface of the printed wiring board on which the printed circuit is provided.
Step (e): After step (d), the printed wiring board with an insulating film and the electromagnetic wave shielding film of the present invention from which the second release film has been peeled are contacted with the conductive adhesive layer on the surface of the insulating film. The conductive adhesive layer is adhered to the surface of the insulating film, and the conductive adhesive layer is electrically connected to the printed circuit through the through-holes by stacking and heat-pressing them. A step of obtaining a printed wiring board with a shield film.
Step (f): A step of peeling off the first release film after the step (e) when the first release film becomes unnecessary.
Step (g): A step of fully curing the anisotropic conductive adhesive layer between the steps (e) and (f) or after the step (f) as necessary.

  Hereinafter, a method for producing a flexible printed wiring board with an electromagnetic wave shielding film will be described with reference to FIG.

(Process (d))
As shown in FIG. 7, an insulating film 60 in which a through hole 62 is formed at a position corresponding to the printed circuit 54 is superimposed on the flexible printed wiring board 50, and an adhesive layer of the insulating film 60 is placed on the surface of the flexible printed wiring board 50. A flexible printed wiring board 3 with an insulating film is obtained by bonding (not shown) and curing the adhesive layer. The adhesive layer of the insulating film 60 may be temporarily bonded to the surface of the flexible printed wiring board 50, and the adhesive layer may be fully cured in the step (g).
Adhesion and curing of the adhesive layer are performed by, for example, hot pressing with a press machine (not shown) or the like.

(Process (e))
As shown in FIG. 7, the electromagnetic shielding film 1 from which the second release film 40 has been peeled is overlapped on the flexible printed wiring board 3 with an insulating film, and heat-pressed, whereby the surface of the insulating film 60 is anisotropically conductive. The flexible printed wiring board 2 with the electromagnetic wave shielding film is obtained in which the adhesive layer 24 is bonded and the anisotropic conductive adhesive layer 24 is electrically connected to the printed circuit 54 through the through hole 62.

The anisotropic conductive adhesive layer 24 is bonded and cured by, for example, hot pressing with a press (not shown) or the like.
The hot pressing time is 20 seconds or more and 60 minutes or less, and more preferably 30 seconds or more and 30 minutes or less. If the hot pressing time is equal to or greater than the lower limit of the above range, the anisotropic conductive adhesive layer 24 is adhered to the surface of the insulating film 60. Further, the insulating resin layer 10 is sufficiently cured, and the peeling force at the interface between the insulating resin layer 10 and the first release film 30 is sufficiently reduced. If the time of hot press is below the upper limit of the said range, the manufacturing time of the flexible printed wiring board 2 with an electromagnetic wave shielding film can be shortened.

  The temperature of the hot press (the temperature of the hot platen of the press machine) is preferably 140 ° C. or higher and 190 ° C. or lower, and more preferably 150 ° C. or higher and 175 ° C. or lower. If the temperature of the hot press is equal to or higher than the lower limit of the above range, the anisotropic conductive adhesive layer 24 is bonded to the surface of the insulating film 60. In addition, the time for hot pressing can be shortened. Further, the insulating resin layer 10 is sufficiently cured, and the peeling force at the interface between the insulating resin layer 10 and the first release film 30 is sufficiently reduced. If the temperature of the hot press 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, etc. can be suppressed.

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

(Process (f))
As shown in FIG. 7, the first release film 30 is peeled from the insulating resin layer 10 when the first release film becomes unnecessary.

(Process (g))
When the time of the hot press in the step (e) is a short time of 20 seconds or more and 10 minutes or less, the anisotropic conductive adhesive layer between the step (e) and the step (f) or after the step (f) It is preferable to perform 24 main curing.
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 from 15 minutes to 120 minutes, preferably from 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 heating time is below the upper limit of the said range, the manufacturing time of the flexible printed wiring board 2 with an electromagnetic wave shielding film can be shortened.
The heating temperature (atmosphere temperature in the oven) is preferably 120 ° C. or higher and 180 ° C. or lower, and preferably 120 ° C. or higher and 150 ° C. or lower. If heating temperature is more than the lower limit of the said range, heating time can be shortened. If heating temperature is below the upper limit of the said range, deterioration etc. of the electromagnetic wave shielding film 1, the flexible printed wiring board 50, etc. can be suppressed.
Heating is preferably performed without pressure from the point that a special apparatus need not be used.

(Function and effect)
In the flexible printed wiring board 2 with the electromagnetic wave shielding film described above, since the electromagnetic wave shielding film 1 is used, the reflection of light on the surface of the insulating resin layer 10 after the first release film 30 is peeled off. It can be suppressed.

(Other embodiments)
The printed wiring board with an electromagnetic wave shielding film of the present invention includes a printed wiring board, an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided, a conductive layer adjacent to the insulating film, and conductive. Any layer may be used as long as it has the electromagnetic wave shielding film of the present invention electrically connected to a printed circuit through a through-hole formed in the insulating film, and is not limited to the illustrated embodiment.
For example, the flexible printed wiring board may have a ground layer on the back side. The flexible printed wiring board may have a printed circuit on both sides, and an insulating film and an electromagnetic wave shielding film may be attached to both sides.
Instead of the flexible printed wiring board, a rigid printed board having no flexibility may be used.
Instead of the electromagnetic shielding film 1 of the first embodiment, the electromagnetic shielding film 1 of the second embodiment, the electromagnetic shielding film 1 of the third embodiment, or the like may be used.

  Examples are shown below. In addition, this invention is not limited to an Example.

(Storage modulus)
The storage elastic modulus was measured using a dynamic viscoelasticity measuring apparatus (RSAII, manufactured by Rheometric Scientific, USA) under the conditions of temperature: 180 ° C., frequency: 1 Hz, temperature increase rate: 10 ° C./min.

(Arithmetic average roughness Ra, average length RSm of roughness curve elements)
The arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve element are measured with a 3D measurement laser microscope (OLYMPUS, LEXT OLS4000). And based on this roughness curve, it calculated | required based on JISB0601: 2013 (corresponding international standard ISO 4287: 1997, Amd.1: 2009).

(Specular gloss)
The specular glossiness of the surface of the insulating resin layer after peeling off the first release film is determined using JIS Z 8741: 1997 (corresponding international standard ISO 2813: 1994, ISO 7668) using a digital variable gloss meter UGV-5D. : 1986), and the measurement was performed under the conditions of an incident angle / light receiving angle of 60 ° / 60 °.

Example 1
20 parts by mass of acrylic particles (manufactured by Soken Chemical Co., Ltd., Chemisnow (registered trademark) MX-300, average particle size: 3 μm) in 100 parts by mass of an acrylic adhesive (manufactured by Soken Chemical Co., Ltd., SK Dyne (registered trademark) 1499M) Was added to prepare an adhesive composition.
The pressure-sensitive adhesive composition was applied to the surface of a PET film (thickness: 50 μm) using an applicator to form a pressure-sensitive adhesive layer (thickness: 2 μm) to obtain a first release film. Table 1 shows the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve elements.

  As the second release film, a PET film whose one side is release-treated with a non-silicone release agent (manufactured by Lintec, T157, release film main body thickness: 50 μm, release agent layer thickness: 0.1 μm) was prepared.

  As an insulating resin layer forming coating material, 100 parts by mass of bisphenol A type epoxy resin (Mitsubishi Chemical Co., Ltd., jER (registered trademark) 828) and 20 masses of curing agent (Showa Denko Co., Ltd., Shoamine X (registered trademark)). Part, 2 parts by mass of 2-ethyl-4-methylimidazole, and 2 parts by mass of carbon black were prepared in 200 parts by mass of a solvent (methyl ethyl ketone).

  As a thermosetting conductive adhesive composition, 100 parts by mass of a thermosetting adhesive (epoxy resin (DIC, EXA-4816) and 20 parts by mass of a curing agent (Ajinomoto Fine-Techno, PN-23). (A latent curable epoxy resin obtained by mixing) and 40 parts by mass of conductive particles (copper particles having an average particle diameter of 7.5 μm) are dissolved or dispersed in 200 parts by mass of a solvent (methyl ethyl ketone). Prepared.

Step (a):
An insulating resin layer-forming paint is applied to the surface of the pressure-sensitive adhesive layer of the first release film, heated at 60 ° C. for 2 minutes, dried and semi-cured, and the insulating resin layer (thickness: 10 μm, 180 Storage modulus at ° C .: 1.8 × 10 ⁷ Pa).

Step (b1):
Copper was physically evaporated on the surface of the insulating resin layer 10 by an electron beam evaporation method to form a metal thin film layer (deposited film, thickness: 0.07 μm, surface resistance: 0.3Ω).

Step (b2):
By applying a thermosetting conductive adhesive composition to the surface of the metal thin film layer using a die coater and volatilizing the solvent to form a B stage, an anisotropic conductive adhesive layer (thickness: 7 μm, Copper particles: 4.5% by volume, storage elastic modulus at 180 ° C .: 1 × 10 ⁴ Pa) were formed.

Step (c):
The 2nd release film was affixed on the surface of the anisotropic conductive adhesive layer, and the electromagnetic wave shielding film as shown in FIG. 1 was obtained.

Step (d):
An insulating adhesive composition made of a nitrile rubber-modified epoxy resin is applied to the surface of a 25 μm-thick polyimide film (surface resistance: 1 × 10 ¹⁷ Ω) (insulating film body) so that the dry film thickness is 25 μm. Then, an adhesive layer was formed to obtain an insulating film (thickness: 50 μm). A through hole (hole diameter: 150 μm) was formed at a position corresponding to the ground of the printed circuit 54.

A flexible printed wiring board having a printed circuit formed on the surface of a 12 μm thick polyimide film (surface resistance: 1 × 10 ¹⁷ Ω) (base film) was prepared.
An insulating film was affixed to the flexible printed wiring board by hot pressing to obtain a flexible printed wiring board with an insulating film.

Step (e):
An electromagnetic shielding film from which the second release film has been peeled is overlaid on a flexible printed wiring board with an insulating film, and using a hot press device (G-12 manufactured by Orihara Seisakusho Co., Ltd.), hot platen temperature: 170 ° C., pressure: 2 MPa Was subjected to hot pressing for 120 seconds, and an anisotropic conductive adhesive layer was temporarily bonded to the surface of the insulating film to obtain a flexible printed wiring board with an electromagnetic wave shielding film.

Steps (f) and (g):
The anisotropic conductive adhesive layer was fully cured by heating the flexible printed wiring board with an electromagnetic wave shielding film at a temperature of 160 ° C. for 1 hour using a high-temperature thermostat (manufactured by Enomoto Kasei Co., Ltd., HT210).
The first release film was peeled from the insulating resin layer. Table 1 shows the specular glossiness of the surface of the insulating resin layer.

(Examples 2-3)
A first release film was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer of the first release film was changed to the thickness shown in Table 1. Table 1 shows the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve elements.
A flexible printed wiring board with an electromagnetic wave shielding film was obtained in the same manner as in Example 1 except that the first release film was changed to the first release film of Example 2 or 3. After the anisotropic conductive adhesive layer was fully cured, the first release film was peeled from the insulating resin layer. Table 1 shows the specular glossiness of the surface of the insulating resin layer.

(Examples 4 to 6)
Thickness shown in Table 1 is the thickness of the pressure-sensitive adhesive layer of the first release film by changing the acrylic particles to acrylic particles (manufactured by Soken Chemical Co., Ltd., Chemisnow (registered trademark) MX-500, average particle size: 5 μm). A first release film was obtained in the same manner as in Example 1 except for changing to. Table 1 shows the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve elements.
A flexible printed wiring board with an electromagnetic wave shielding film was obtained in the same manner as in Example 1 except that the first release film was changed to the first release film of Example 4, 5 or 6. After the anisotropic conductive adhesive layer was fully cured, the first release film was peeled from the insulating resin layer. Table 1 shows the specular glossiness of the surface of the insulating resin layer.

(Examples 7 to 12)
Acrylic particles were changed to silica particles (manufactured by Fuji Silysia Chemical Co., Silo Hovic 100, average particle size: 2.7 μm), and for Examples 7 to 9, the amount of particles added was changed to 10 parts by mass. A first release film was obtained in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer of the release film was changed to the thickness shown in Table 1. Table 1 shows the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve elements.
A flexible printed wiring board with an electromagnetic wave shielding film is obtained in the same manner as in Example 1 except that the first release film is changed to the first release film of Example 7, 8, 9, 10, 11 or 12. It was. After the anisotropic conductive adhesive layer was fully cured, the first release film was peeled from the insulating resin layer. Table 1 shows the specular glossiness of the surface of the insulating resin layer.

(Comparative Example 1)
A first release film was obtained in the same manner as in Example 1 except that the acrylic particles were not added and the thickness of the pressure-sensitive adhesive layer of the first release film was changed to 9 μm. Table 1 shows the arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film and the average length RSm of the roughness curve elements.
A flexible printed wiring board with an electromagnetic wave shielding film was obtained in the same manner as in Example 1 except that the first release film was changed to the first release film of Comparative Example 1. After the anisotropic conductive adhesive layer was fully cured, the first release film was peeled from the insulating resin layer. Table 1 shows the specular glossiness of the surface of the insulating resin layer.

  The electromagnetic wave shielding film of the present invention is useful as an electromagnetic wave shielding member in flexible printed wiring boards for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game machines, notebook computers, and medical devices.

1 electromagnetic shielding film,
2 Flexible printed wiring board with electromagnetic shielding film,
3 Flexible printed wiring board with insulating film,
10 Insulating resin layer,
20 conductive layer,
22 metal thin film layer,
24 anisotropic conductive adhesive layer,
24a thermosetting adhesive,
24b conductive particles,
26 isotropic conductive adhesive layer,
26a thermosetting adhesive,
26b conductive particles,
30 First release film,
32 release film body,
34 adhesive layer,
34a adhesive,
34b particles,
40 Second release film,
42 release film body,
44 release agent layer,
50 Flexible printed wiring boards,
52 Base film,
54 printed circuit,
60 insulation film,
62 Through-hole.

Claims (9)

An insulating resin layer;
A conductive layer adjacent to the insulating resin layer;
A first release film adjacent to the side of the insulating resin layer opposite to the conductive layer;
The first release film has an adhesive layer in contact with the insulating resin layer,
The electromagnetic wave shielding film in which the said adhesive layer contains an adhesive and particle | grains.   The electromagnetic wave shielding film according to claim 1, wherein an average particle diameter of the particles is 0.5 μm or more and 15 μm or less.   The electromagnetic wave shielding film according to claim 1 or 2, wherein the particles are at least one selected from the group consisting of silica particles and acrylic particles.   The electromagnetic wave shielding film according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a thickness of 0.5 µm or more and 10 µm or less.   The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein the mirror glossiness of the surface of the insulating resin layer after peeling off the first release film is 0.5 or more and 40 or less.   The electromagnetic wave shielding film according to any one of claims 1 to 5, wherein an arithmetic average roughness Ra of the surface of the pressure-sensitive adhesive layer of the first release film is 0.2 µm or more and 2.5 µm or less.   The average length RSm of the roughness curve element on the surface of the pressure-sensitive adhesive layer of the first release film is 0.01 mm or more and 0.1 mm or less, according to any one of claims 1 to 6. Electromagnetic shielding film.   The electromagnetic wave shielding film according to claim 1, further comprising a second release film adjacent to the side of the conductive layer opposite to the insulating resin layer. A printed wiring board provided with a printed circuit on at least one side of the substrate;
An insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided;
The said conductive layer is adjacent to the said insulating film, and the said conductive layer is electrically connected to the said printed circuit through the through-hole formed in the said insulating film. A printed wiring board with an electromagnetic wave shielding film, comprising:

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