JP7424745B2 - Electromagnetic shielding film, printed wiring board with electromagnetic shielding film, and manufacturing method thereof - Google Patents

Description

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

In order to shield electromagnetic noise generated from printed wiring boards and electromagnetic noise from outside, an electromagnetic shielding film having an insulating resin layer and a conductive layer is applied to the surface of the printed wiring board via an insulating film (coverlay film). (For example, see Patent Document 1). The conductive layer includes, for example, a metal thin film layer for shielding electromagnetic waves and an anisotropic conductive adhesive layer for electrically connecting the metal thin film layer and the printed circuit of the printed wiring board.

When providing an electromagnetic shielding film on the surface of a printed wiring board, the printed wiring board with an insulating film and the electromagnetic shielding film are stacked so that the insulating film and the anisotropic conductive adhesive layer are in contact with each other, and then they are heat-pressed. Crimp. At this time, the anisotropically conductive adhesive layer of the electromagnetic shielding film comes into contact with the printed circuit (ground) of the printed wiring board through the through hole formed in the insulating film. The printed circuit is electrically connected.

JP 2017-220592 Publication

However, when the anisotropically conductive adhesive layer of the electromagnetic shielding film is bonded to the printed circuit of the printed wiring board through the through-hole of the insulating film, the contact between the printed circuit and the anisotropically conductive adhesive layer is insufficient. Cheap. If the contact between the printed circuit and the anisotropic conductive adhesive layer is insufficient, the connection resistance between the printed circuit and the metal thin film layer increases, and electrical connection may not be established reliably.

In order to ensure electrical connection between the printed circuit and the metal thin film layer, it is necessary to hot press the printed wiring board with the insulating film and the electromagnetic shielding film at high pressure. However, when hot-pressed at high pressure, the electromagnetic shielding film and printed wiring board are likely to be damaged.

The present invention provides an anisotropically conductive adhesive of an electromagnetic shielding film that passes through a through hole in an insulating film and attaches to a printed circuit of a printed wiring board, even when the pressure is low during pressure bonding between a printed wiring board with an insulating film and an electromagnetic shielding film. To provide an electromagnetic shielding film that can reliably bond layers and reliably electrically connect a metal thin film layer of the electromagnetic shielding film to a printed circuit.
The present invention provides that an anisotropically conductive adhesive layer of an electromagnetic shielding film is reliably bonded to a printed circuit of a printed wiring board through a through hole of an insulating film provided on the surface of the printed wiring board, and that To provide a printed wiring board with an electromagnetic shielding film in which a metal thin film layer of the electromagnetic shielding film is reliably electrically connected.
The present invention provides an anisotropically conductive adhesive of an electromagnetic shielding film that passes through a through hole in an insulating film and attaches to a printed circuit of a printed wiring board, even when the pressure is low during pressure bonding between a printed wiring board with an insulating film and an electromagnetic shielding film. To provide a method for producing a printed wiring board with an electromagnetic shielding film, in which the layers are surely adhered and a metal thin film layer of the electromagnetic shielding film is surely electrically connected to the printed circuit.

The present invention has the following aspects.
<1> An insulating resin layer, a metal thin film layer, and an anisotropically conductive adhesive layer containing an adhesive and conductive particles are sequentially provided, and the thickness of the adhesive in the anisotropically conductive adhesive layer is A. and the average particle diameter B of the conductive particles satisfy the relationship of 1.1A≦B≦3.0A, and the thickness A of the adhesive is 3 μm or more.
<2> The electromagnetic shielding film according to <1>, wherein the proportion of the conductive particles is 5% by mass or more and 50% by mass or less out of 100% by mass of the anisotropically conductive adhesive layer.
<3> A printed wiring board having a printed circuit provided on at least one side of the substrate, an insulating film adjacent to the side of the printed wiring board on which the printed circuit is provided, and the anisotropic conductive adhesive layer. The electromagnetic shield according to <1> or <2>, which is adjacent to the insulating film and in which the anisotropically conductive adhesive layer is electrically connected to the printed circuit through a through hole formed in the insulating film. A printed wiring board with an electromagnetic shielding film.
<4> A printed wiring board with a printed circuit provided on at least one side of the board, and an insulating film adjacent to the side of the printed wiring board on which the printed circuit is provided, and a through hole in the insulating film. An electromagnetic wave shield in which the formed printed wiring board with an insulating film and the electromagnetic wave shielding film of <1> or <2> are stacked and crimped so that the insulating film and the anisotropically conductive adhesive layer are in contact with each other. A method for manufacturing a printed wiring board with a film.
<5> The method for manufacturing a printed wiring board with an electromagnetic shielding film according to <4>, wherein the printed wiring board with an insulating film and the electromagnetic shielding film are pressure-bonded at a pressure of 3 MPa or less.

According to the electromagnetic shielding film of the present invention, even if the pressure at the time of pressure bonding between the printed wiring board with the insulating film and the electromagnetic shielding film is low, the electromagnetic shielding film passes through the through hole of the insulating film and connects to the printed circuit of the printed wiring board. The anisotropic conductive adhesive layer can be reliably bonded, and the metal thin film layer of the electromagnetic shielding film can be reliably electrically connected to the printed circuit.
The printed wiring board with an electromagnetic shielding film of the present invention ensures that the anisotropically conductive adhesive layer of the electromagnetic shielding film passes through the through hole of the insulating film provided on the surface of the printed wiring board and onto the printed circuit of the printed wiring board. At the same time, the metal thin film layer of the electromagnetic shielding film is firmly electrically connected to the printed circuit.
According to the printed wiring board with an electromagnetic shielding film of the present invention, even when the pressure is low when the printed wiring board with an insulating film and the electromagnetic shielding film are crimped, the printed circuit of the printed wiring board passes through the through hole of the insulating film. It is possible to manufacture a printed wiring board with an electromagnetic shielding film in which the anisotropic conductive adhesive layer of the electromagnetic shielding film is reliably bonded and the metal thin film layer of the electromagnetic shielding film is reliably electrically connected to the printed circuit.

FIG. 1 is a cross-sectional view showing an example of an electromagnetic shielding film of the present invention. FIG. 1 is a cross-sectional view showing an example of a printed wiring board with an electromagnetic shielding film of the present invention. FIG. 3 is a cross-sectional view showing a manufacturing process of the printed wiring board with an electromagnetic shielding film shown in FIG. 2. FIG.

The following definitions of terms apply throughout the specification and claims.
"Anisotropically conductive adhesive layer" means a conductive adhesive layer that has conductivity in the thickness direction and does not have conductivity in the planar direction.
"A conductive adhesive layer having no conductivity in the surface direction" means a conductive adhesive layer having a surface resistance of 1×10 ⁴ Ω/□ or more.
The average particle diameter of the conductive particles is a volume-based cumulative 50% diameter (d50) determined by a laser diffraction/scattering method.
The thickness of the film (carrier film, release film, insulating film, etc.) and coating film (insulating resin layer, adhesive in the anisotropic conductive adhesive layer, etc.) was measured using a digital length measuring machine (Lightmatic VL manufactured by Mitutoyo). -50-B) was used to measure the thickness at five randomly selected locations, and the average value was obtained.
The thickness of the metal thin film layer is the average value of the thicknesses measured at five randomly selected locations using an eddy current film thickness meter.
The storage modulus is calculated from the stress applied to the measurement object and the detected strain, and is measured as one of the viscoelastic properties using a dynamic viscoelasticity measurement device that outputs the output as a function of temperature or time.
The 10% compressive strength of the conductive particles is determined by the following formula (α) from the measurement results using a micro compression tester.
C(x)=2.48P/πd ² ...(α)
However, C(x) is the 10% compressive strength (MPa), P is the test force (N) at the time of 10% displacement of the particle diameter, and d is the particle diameter (mm).
Surface resistance can be measured using the four ^- terminal method (JIS K 7194:1994 and If it is 10 ⁶ Ω/□ or more, use the product name Hiresta (Hiresta UP, URS probe) and double ring method (JIS K 6911:2006).
The dimensional ratios in FIGS. 1 to 3 are different from the actual ones for convenience of explanation.

<Electromagnetic shielding film>
A first aspect of the present invention has an insulating resin layer, a metal thin film layer, and an anisotropic conductive adhesive layer containing an adhesive and conductive particles in this order, and the adhesive in the anisotropic conductive adhesive layer This is an electromagnetic shielding film in which the thickness A of the adhesive and the average particle diameter B of the conductive particles satisfy a specific relationship, and the thickness A of the adhesive is within a specific range.

FIG. 1 is a sectional view showing an example of the electromagnetic shielding film of this embodiment.
The electromagnetic shielding film 1 includes 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 an insulating resin of the conductive layer 20 . It has a release film 40 adjacent to the layer 10 on the opposite side.
The conductive layer 20 has a metal thin film layer 22 adjacent to the insulating resin layer 10 and an anisotropic conductive adhesive layer 24 adjacent to the release film 40.

The thickness of the electromagnetic shielding film 1 (excluding the carrier film 30 and release film 40) is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less. If the thickness of the electromagnetic shielding film 1 that does not include the carrier film 30 and the release film 40 is at least the lower limit of the above range, it will be difficult to break when the carrier film 30 is peeled off. If the thickness of the electromagnetic shielding film 1 that does not include the carrier film 30 and the release film 40 is less than or equal to the upper limit of the above range, the printed wiring board with the electromagnetic shielding film can be made thinner.

(insulating resin layer)
The insulating resin layer 10 becomes a protective layer for the conductive layer 20 after the electromagnetic shielding film 1 is attached 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 is a coating film formed by applying a paint containing a thermosetting resin and a curing agent and semi-curing or curing; a coating film formed by applying a paint containing a thermoplastic resin and drying it. Coating film: A layer made of a film formed by melt-molding a composition containing a thermoplastic resin, etc. can be mentioned. From the viewpoint of heat resistance when subjected to a solder reflow process, a coating film formed by applying a coating containing a thermosetting resin and a curing agent and semi-curing or curing the coating is preferable.

Examples of thermosetting resins include amide resins, epoxy resins, phenol resins, amino resins, alkyd resins, urethane resins, synthetic rubbers, and ultraviolet-curing acrylate resins. As the thermosetting resin, amide resins and epoxy resins are preferable because they have excellent heat resistance.
Examples of the curing agent include known curing agents depending on the type of thermosetting resin.
Examples of the thermoplastic resin include aromatic polyetherketone, polyimide, polyamideimide, polyamide, polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyphenylene sulfide ketone.

The insulating resin layer 10 contains one or more of a colorant (pigment, dye, etc.) and a filler in order to hide the printed circuit of the printed wiring board and to add design to the printed wiring board with an electromagnetic shielding film. It may contain both.
As one or both of the colorant and filler, pigments or fillers are preferable from the viewpoint of weather resistance, heat resistance, and hiding properties, and from the viewpoint of hiding properties of printed circuits and design, black pigments, black pigments, and others are preferable. A combination with a pigment or a combination of a black pigment and a filler is more preferable.
The insulating resin layer 10 may contain a flame retardant.
The insulating resin layer 10 may contain other components as necessary within a range that does not impair the effects of the present invention.

The surface resistance of the insulating resin layer 10 is preferably 1×10 ⁶ Ω/□ or more from the viewpoint of electrical insulation. From a practical point of view, the surface resistance of the insulating resin layer 10 is preferably 1×10 ¹⁹ Ω/□ or less.
The thickness of the insulating resin layer 10 is preferably 0.1 μm or more and 30 μm or less, more preferably 0.5 μm or more and 20 μm or less. If the thickness of the insulating resin layer 10 is at least the lower limit of the above range, the insulating resin layer 10 can fully exhibit its function as a protective layer. If the thickness of the insulating resin layer 10 is less than or equal to the upper limit of the above range, the electromagnetic shielding film 1 can be made thinner.

(conductive layer)
Since the conductive layer 20 includes the metal thin film layer 22 adjacent to the insulating resin layer 10 and the anisotropically conductive adhesive layer 24 adjacent to the release film 40, the electromagnetic wave shielding property is sufficiently high.

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 plane direction, it has conductivity in the plane direction and functions as an electromagnetic shielding layer or the like.

As the metal thin film layer 22, a vapor deposited film formed by physical vapor deposition (vacuum vapor deposition, sputtering, ion beam vapor deposition, electron beam vapor deposition, etc.) or CVD (chemical vapor deposition), a plated film formed by plating, metal foil, etc. can be mentioned. In terms of superior in-plane conductivity, the metal thin film layer 22 is preferably a vapor deposited film or a plated film. A vapor deposited film is more preferable for the metal thin film layer 22 in that the metal thin film layer 22 can be made thin, has excellent in-plane conductivity even if it is thin, and can be easily formed by a dry process, and a vapor deposited film by physical vapor deposition. is even more preferable.

Examples of the metal constituting the metal thin film layer 22 include aluminum, silver, copper, gold, and conductive ceramics, with silver or copper being preferred from the viewpoint of electrical conductivity.
Among the metal thin film layers 22, a metal vapor deposition layer is preferable, and a silver vapor deposition layer or a copper vapor deposition layer is more preferable, since it has a high electromagnetic wave shielding property and can easily form a metal thin film.

The surface resistance of the metal thin film layer 22 is preferably from 0.001 Ω/□ to 1 Ω/□, more preferably from 0.001 Ω/□ to 0.5 Ω/□. If the surface resistance of the metal thin film layer 22 is at least 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 below the upper limit of the above range, it can fully function as an electromagnetic shielding layer.

The thickness of the metal thin film layer 22 is preferably 0.01 μm or more and 5 μm or less, 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 conductivity in the plane direction will be even better. If the thickness of the metal thin film layer 22 is 0.05 μm or more, the electromagnetic noise shielding effect will be even better. If the thickness of the metal thin film layer 22 is less than or equal to the upper limit of the above range, the electromagnetic shielding film 1 can be made thinner. Moreover, the productivity and flexibility of the electromagnetic shielding film 1 are improved.

Anisotropic conductive adhesive layer:
The anisotropically conductive adhesive layer 24 has conductivity in the thickness direction, has no conductivity in the surface direction, and has adhesive properties.
The anisotropic conductive adhesive layer 24 allows the conductive adhesive layer to be easily made thinner and the amount of conductive particles (described later) to be reduced.As a result, the electromagnetic shielding film 1 can be made thinner and the electromagnetic shielding film 1 can be It has the advantage of high performance.

As the anisotropic conductive adhesive layer 24, a thermosetting conductive adhesive layer is preferable since it can exhibit heat resistance after curing. The thermosetting anisotropic conductive adhesive layer 24 may be in an uncured state or may be in a B-staged state.
The thermosetting anisotropically conductive adhesive layer 24 includes, for example, a thermosetting adhesive 24a and conductive particles 24b. The thermosetting anisotropically conductive adhesive layer 24 may contain a flame retardant, if necessary.

Examples of the thermosetting adhesive 24a include epoxy resin, phenol resin, amino resin, alkyd resin, urethane resin, synthetic rubber, and ultraviolet-curing acrylate resin. Epoxy resin is preferred because it has excellent heat resistance. The epoxy resin may contain a rubber component (carboxy-modified nitrile rubber, acrylic rubber, etc.) for imparting flexibility, a tackifier, and the like.
The thermosetting adhesive 24a may contain cellulose resin and microfibrils (glass fibers, etc.) in order to increase the strength of the anisotropically conductive adhesive layer 24 and improve punching characteristics. The thermosetting adhesive 24a may contain other components (curing agent, etc.) as necessary, within a range that does not impair the effects of the present invention.

Examples of the conductive particles 24b include metal particles (silver, platinum, gold, copper, nickel, palladium, aluminum, solder, etc.), graphite powder, fired carbon particles, plated fired carbon particles, and the like. As the conductive particles 24b, the anisotropically conductive adhesive layer 24 has a further appropriate hardness, and the pressure loss in the anisotropically conductive adhesive layer 24 during hot pressing can be further reduced. , metal particles are preferred, and copper particles are more preferred.

The 10% compressive strength of the conductive particles 24b is preferably 30 MPa or more and 200 MPa or less, more preferably 50 MPa or more and 150 MPa or less, and even more preferably 70 MPa or more and 100 MPa or less. If the 10% compressive strength of the conductive particles 24b is equal to or higher than the lower limit of the above range, the anisotropic conductive adhesive layer 24 can be insulated without significantly losing the pressure applied to the metal thin film layer 22 during hot pressing. Electrical connection is ensured by a printed circuit on a printed wiring board through the through hole in the film. If the 10% compressive strength of the conductive particles 24b is below the upper limit of the above range, the contact with the metal thin film layer 22 will be good and the electrical connection will be reliable.

The thickness A of the thermosetting adhesive 24a in the anisotropic conductive adhesive layer 24 and the average particle diameter B of the conductive particles 24b satisfy the relationship of 1.1A≦B≦3.0A.
If the average particle diameter B of the conductive particles 24b is 1.1 times or more the thickness A of the thermosetting adhesive 24a, the thermosetting adhesive It is easy to be exposed on the surface of the anisotropically conductive adhesive layer 24 without being buried in the anisotropically conductive adhesive layer 24a. Therefore, when the anisotropic conductive adhesive layer 24 of the electromagnetic shielding film 1 is adhered to the printed circuit of the printed wiring board through the through-hole of the insulating film, the conductive particles 24b are printed in contact with the metal thin film layer 22. Easy to contact the circuit.
If the average particle diameter B of the conductive particles 24b is 3.0 times or less the thickness A of the thermosetting adhesive 24a, the electromagnetic shielding film 1 can pass through the through hole of the insulating film and connect to the printed circuit of the printed wiring board. When the anisotropically conductive adhesive layer 24 is bonded, the thermosetting adhesive 24a tends to come into contact with the printed circuit.
It is preferable that the thickness A of the thermosetting adhesive 24a and the average particle diameter B of the conductive particles 24b satisfy the relationship of 1.2A≦B≦2.5A.

The thickness A of the thermosetting adhesive 24a is 3 μm or more, 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 A of the thermosetting adhesive 24a is at least the lower limit of the above range, the fluidity of the anisotropically conductive adhesive layer 24 (followability to the shape of the through hole of the insulating film) can be ensured, and the insulation The inside of the through-hole of the film can be sufficiently filled with the thermosetting adhesive 24a. Therefore, when the anisotropic conductive adhesive layer 24 of the electromagnetic shielding film 1 is adhered to the printed circuit of the printed wiring board through the through hole of the insulating film, the thermosetting adhesive 24a easily comes into contact with the printed circuit. If the thickness A of the thermosetting adhesive 24a is below the upper limit of the above range, the electromagnetic shielding film 1 can be made thinner. Further, the flexibility of the electromagnetic shielding film 1 is improved.

From the above, the thickness A of the thermosetting adhesive 24a and the average particle diameter B of the conductive particles 24b satisfy the relationship of 1.1A≦B≦3.0A, and the thickness of the thermosetting adhesive 24a If the thickness A is 3 μm or more, even if the pressure is low when the printed wiring board with insulating film and the electromagnetic shielding film 1 are bonded together, the anisotropic conductive adhesive layer will pass through the through hole of the insulating film and attach to the printed circuit. 24 can be reliably bonded, and the metal thin film layer 22 can be reliably electrically connected to the printed circuit.

The average particle diameter B of the conductive particles 24b in the anisotropic conductive adhesive layer 24 is preferably 3.6 μm or more and 62.5 μm or less, more preferably 6 μm or more and 37.5 μm or less. If the average particle diameter B of the conductive particles 24b is equal to or larger than the lower limit of the above range, the thickness A of the thermosetting adhesive 24a can be ensured, and sufficient adhesive strength can be obtained. If the average particle diameter of the conductive particles 24b is below the upper limit of the above range, the fluidity of the anisotropically conductive adhesive layer 24 can be ensured, and as described later, the anisotropically conductive adhesive layer 24 can be bonded to an insulating film. When pushed into the through hole, the inside of the through hole of the insulating film can be sufficiently filled with the conductive adhesive.

The proportion of the conductive particles 24b in the anisotropically conductive adhesive layer 24 is preferably 5% by mass or more and 50% by mass or less out of 100% by volume of the anisotropically conductive adhesive layer 24. If the proportion of the conductive particles 24b is at least the lower limit of the above range, the anisotropically conductive adhesive layer 24 will have good conductivity, and the metal thin film layer 22 can be electrically connected to the printed circuit more reliably. If the proportion of the conductive particles 24b is below 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 will be good. Further, the flexibility of the electromagnetic shielding film 1 is improved.

The storage modulus of the anisotropic conductive adhesive layer 24 at 180° C. is preferably 1×10 ³ Pa or more and 5×10 ⁷ Pa or less, more preferably 5×10 ³ Pa or more and 1×10 ⁷ Pa or less. If the storage elastic modulus of the anisotropically conductive adhesive layer 24 at 180° C. is equal to or higher than the lower limit of the above range, the anisotropically conductive adhesive layer 24 will have a more appropriate hardness, and will be difficult to heat during hot pressing. The pressure loss in the anisotropically conductive adhesive layer 24 can be reduced. As a result, the anisotropically conductive adhesive layer 24 is reliably bonded to the printed circuit of the printed wiring board through the through hole of the insulating film, and the metal thin film layer 22 is electrically connected to the printed circuit more reliably. Ru. If the storage elastic modulus at 180° C. of the anisotropically conductive adhesive layer 24 is below the upper limit of the above range, the flexibility of the electromagnetic shielding film 1 will be improved. As a result, the electromagnetic shielding film 1 easily sinks into the through-hole of the insulating film, and the anisotropically conductive adhesive layer 24 passes through the through-hole of the insulating film and is reliably bonded to the printed circuit of the printed wiring board. , the metal thin film layer 22 is electrically connected to the printed circuit more reliably.

The surface resistance of the anisotropic conductive adhesive layer 24 is preferably 1×10 ⁴ Ω/□ or more and 1×10 ¹⁶ Ω/□ or less, more preferably 1×10 ⁶ Ω/□ or more and 1×10 ¹⁴ Ω/□ or less. preferable. If the surface resistance of the anisotropically conductive adhesive layer 24 is at least the lower limit of the above range, the content of the conductive particles 24b can be kept low. As long as the surface resistance of the anisotropically conductive adhesive layer 24 is less than or equal to the upper limit of the above range, there is no practical problem with anisotropy.

(carrier film)
The carrier film 30 is a support that reinforces and protects the insulating resin layer 10 and the conductive layer 20, and improves the handling properties of the electromagnetic shielding film 1. In particular, when a thin film, specifically a film with a thickness of 3 μm or more and 10 μm or less, is used as the insulating resin layer 10, the insulating resin layer 10 can be prevented from breaking by having the carrier film 30.
The carrier film 30 is peeled off from the insulating resin layer 10 after the electromagnetic shielding film 1 is attached to a printed wiring board or the like.

The carrier film 30 used in this embodiment has a carrier film main body 32 and a mold release agent layer 34 provided on the surface of the carrier film main body 32 on the insulating resin layer 10 side.

Examples of resin materials for the carrier film body 32 include polyethylene terephthalate (hereinafter also referred to as "PET"), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, and ethylene. - Vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. As the resin material, PET is preferable from the viewpoint of heat resistance (dimensional stability) and cost when manufacturing the electromagnetic shielding film 1.

The carrier film main body 32 may contain one or both of a colorant (pigment, dye, etc.) and a filler.
As the coloring agent and/or filler, one of a color different from that of the insulating resin layer 10 is used because it can be clearly distinguished from the insulating resin layer 10 and it is easy to notice that the carrier film 30 remains unpeeled after hot pressing. Preferably, a white pigment, a filler, a combination of a white pigment and another pigment, or a combination of a white pigment and a filler is more preferable.

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

The thickness of the carrier film main body 32 is preferably 3 μm or more and 75 μm or less, more preferably 12 μm or more and 50 μm or less. If the thickness of the carrier film main body 32 is at least the lower limit of the above range, the handling properties of the electromagnetic shielding film 1 will be good. If the thickness of the carrier film main body 32 is below the upper limit of the above range, the anisotropically conductive adhesive layer 24 of the electromagnetic shielding film 1 is hot-pressed on the surface of the insulating film. Heat is easily transferred to.

The mold release agent layer 34 is formed by treating the surface of the carrier film body 32 with a mold release agent. By having the release agent layer 34 in the carrier film 40, when the carrier film 40 is peeled off from the insulating resin layer 10, the carrier film 40 can be easily peeled off, and the insulating resin layer 10 can be difficult to break.
As the mold release agent, any known mold release agent may be used.

The thickness of the release agent layer 34 is preferably 0.05 μm or more and 30 μm or less, more preferably 0.1 μm or more and 20 μm or less. If the thickness of the release agent layer 34 is within the above range, the carrier film 30 can be further easily peeled off.

The thickness of the carrier film 30 is preferably 25 μm or more and 125 μm or less, more preferably 38 μm or more and 100 μm or less. If the thickness of the carrier film 30 is at least the lower limit of the above range, the electromagnetic shielding film 1 will have good handling properties. If the thickness of the carrier film 30 is less than or equal to the upper limit of the above range, when the anisotropically conductive adhesive layer 24 of the electromagnetic shielding film 1 is hot-pressed on the surface of the insulating film, the anisotropically conductive adhesive layer 24 Heat is easily transmitted.

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

The release film 40 includes, for example, a release film body 42 and a release agent layer 44 provided on the surface of the release film body 42 on the anisotropically conductive adhesive layer 24 side.

Examples of the resin material for the release film body 42 include those similar to the resin material for the carrier film body 32.
The release film body 42 may contain a colorant, a filler, and the like.
The thickness of the release film 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 even more 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 body 42 with a release agent. Since the release film 40 has the release agent layer 44, when the release film 40 is peeled off from the anisotropic conductive adhesive layer 24, the release film 40 can be easily peeled off, and the anisotropic conductive adhesive layer 24 becomes difficult to break.
As the mold release agent, any known mold 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, 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 will be easier to peel off.

(Method for manufacturing electromagnetic shielding film)
Examples of the method for manufacturing the electromagnetic shielding film 1 include the following method (A1) or method (A2).

Method (A1) is a method having the following steps (A1-1) to (A1-4).
Step (A1-1): Step of forming the insulating resin layer 10 on one side of the carrier film 30.
Step (A1-2): A step of forming a metal thin film layer 22 on the surface of the insulating resin layer 10 opposite to the carrier film 30.
Step (A1-3): 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): A step of laminating a release film 40 on the surface of the anisotropically conductive adhesive layer 24 opposite to the metal thin film layer 22.
Each step of method (A1) will be described in detail below.

Examples of the method for forming the insulating resin layer 10 in step (A1-1) include the following method.
- A method of applying a paint containing a thermosetting resin and a curing agent to the surface of the carrier film 30 on the mold release agent layer 34 side and semi-curing or curing it.
- A method of applying a paint containing a thermoplastic resin to the surface of the carrier film 30 on the side of the mold release agent layer 34 and drying it.
- A method in which a film formed by extrusion molding a composition containing a thermoplastic resin is directly laminated on the surface of the carrier film 30 on the mold release agent layer 34 side.
Among these methods, from the viewpoint of heat resistance during soldering etc., a paint containing a thermosetting resin and a curing agent is applied to the surface of the carrier film 30 on the side of the mold release agent layer 34, and semi-cured. Alternatively, a method of curing is preferred.
Examples of paint application methods include die coater, gravure coater, roll coater, curtain flow coater, spin coater, bar coater, reverse coater, kiss coater, fountain coater, rod coater, air doctor coater, knife coater, blade coater, and casting. Methods using various coaters such as coaters and screen coaters can be applied.
When semi-curing or curing the thermosetting resin, it may be heated using a heater such as a heater or an infrared lamp.

Methods for forming the metal thin film layer in step (A1-2) include physical vapor deposition, a method of forming a vapor deposited film by CVD (chemical vapor deposition), a method of forming a plated film by plating, a method of pasting metal foil, etc. can be mentioned. A method of forming a vapor deposited film by physical vapor deposition or CVD, or a method of forming a plated film by plating is preferred from the viewpoint of forming a metal thin film layer having excellent in-plane conductivity. Physical vapor deposition, CVD, etc. can be used because the thickness of the metal thin film layer can be reduced, the metal thin film layer can be formed with excellent in-plane conductivity even if the thickness is thin, and the metal thin film layer can be easily formed using a dry process. A method of forming a vapor deposited film by physical vapor deposition is more preferable, and a method of forming a vapor deposited film by physical vapor deposition is even more preferable.

In step (A1-3), a 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 paint includes a thermosetting adhesive 24a, conductive particles 24b, and a solvent.
Solvents contained in conductive adhesive paints 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 glycyl monomethyl ether, propylene glycol, etc.).
Examples of the method for applying the conductive adhesive paint include a die coater, gravure coater, roll coater, curtain flow coater, spin coater, bar coater, reverse coater, kiss coater, fountain coater, rod coater, air doctor coater, knife coater, Methods using various coaters such as a blade coater, cast coater, and screen coater can be applied.
The anisotropic conductive adhesive layer 24 is formed by volatilizing the solvent from the applied conductive adhesive paint.

In step (A1-4), a release film 40 is placed on the surface of the anisotropic conductive adhesive layer 24 opposite to the metal thin film layer 22, and a release agent layer 44 is placed on the anisotropic conductive adhesive layer 24. Stack them so that they touch each other.
After laminating the release film 40 on the anisotropic conductive adhesive layer 24, a laminate consisting of 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 formed. In addition, pressure treatment may be applied to increase the adhesion between each layer.
The pressure in the pressure treatment is preferably 0.1 kPa or more and 100 kPa or less, more preferably 0.1 kPa or more and 20 kPa or less, and even more preferably 1 kPa or more and 10 kPa or less.
Heating may be performed simultaneously with the pressure treatment. The heating temperature at that time is preferably 50°C or more and 100°C or less.

Method (A2) is a method having the following steps (A2-1) to (A2-4).
Step (A2-1): Step of forming the insulating resin layer 10 on one side of the carrier film 30.
Step (A2-2): Step of forming the metal thin film layer 22 on the surface of the insulating resin layer 10 opposite to the carrier film 30 to obtain the laminate I.
Step (A2-3): Step of forming an anisotropically conductive adhesive layer 24 on one side of the release film 40 to obtain a laminate II.
Step (A2-4): A step of bonding the laminate I and the laminate II so that the metal thin film layer 22 of the laminate I and the anisotropically conductive adhesive layer 24 of the laminate II are in contact with each other.

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

In step (A2-3), a conductive adhesive paint 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 paint and the application method are the same as the step (A1-3) in the method (A1).

In the bonding of the laminate I and the laminate II in step (A2-4), a pressure treatment may be applied to increase the adhesion between the laminate I and the laminate II. The pressurizing conditions are the same as the pressurizing treatment in step (A1-4). Also, in step (A2-4), heating may be performed in the same manner as in step (A1-4).

(Other embodiments)
The electromagnetic wave shielding film of this embodiment has an insulating resin layer, a metal thin film layer, and an anisotropically conductive adhesive layer containing an adhesive and conductive particles in this order. It is sufficient that the thickness A and the average particle diameter B of the conductive particles satisfy the relationship of 1.1A≦B≦3.0A, and the thickness A of the adhesive is 3 μm or more. Not limited to form.
For example, if the insulating resin layer 10 has sufficient flexibility and strength, the carrier film 30 may be omitted.
If the adhesive force of the surface of the anisotropically conductive adhesive layer 24 is low, the release film 40 may be omitted.
The carrier film 30 does not need to have the release agent layer 34 when the carrier film main body 32 alone has sufficient mold release properties.
The release film 40 does not need to have the release agent layer 44 if the release film body 42 alone has sufficient release properties.

<Printed wiring board with electromagnetic shielding film>
A second aspect of the present invention provides a printed wiring board in which a printed circuit is provided 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 an anisotropic conductive adhesive. an electromagnetic shielding film according to the above embodiment, wherein the adhesive layer is adjacent to the insulating film, and the anisotropically conductive adhesive layer is electrically connected to the printed circuit through a through hole formed in the insulating film. It is a printed wiring board.

FIG. 2 is a sectional view showing an example of a printed wiring board with an electromagnetic shielding film of this embodiment.
The printed wiring board 2 with an electromagnetic shielding film includes a flexible printed wiring board 50, an insulating film 60, and an electromagnetic shielding film 1.
The flexible printed wiring board 50 includes a base film 52 and a printed circuit 54 provided on at least one side thereof.
Insulating film 60 is provided on the surface of flexible printed wiring board 50 on the side where printed circuit 54 is provided.
The anisotropically conductive adhesive layer 24 of the electromagnetic shielding film 1 is adhered to the surface of the insulating film 60 and cured. Further, the anisotropic conductive adhesive layer 24 is reliably bonded to the printed circuit 54 through a through hole (not shown) formed in the insulating film 60, and also securely connects the printed circuit 54 and the metal thin film layer 22. electrically connected to.
In the printed wiring board 2 with an electromagnetic shielding film, the release film is peeled off from the anisotropically conductive adhesive layer 24.

When the carrier film 30 is no longer needed in the printed wiring board 2 with electromagnetic shielding film, the carrier film 30 is peeled off from the insulating resin layer 10.

The metal thin film layer 22 of the electromagnetic shielding film 1 has an insulating film 60 and an anisotropically conductive adhesive layer 24 in the vicinity of the printed circuit 54 (signal circuit, ground circuit, ground layer, etc.) except for the part with the through hole. They are arranged opposite to each other and spaced apart from each other.
The distance between the printed circuit 54 and the metal thin film layer 22 excluding the portion with the through hole is approximately equal to the sum of the thickness of the insulating film 60 and the thickness of the anisotropically conductive adhesive layer 24. The separation distance is preferably 30 μm or more and 200 μm or less, more preferably 60 μm or more and 200 μm or less. If the separation distance is less than 30 μm, the impedance of the signal circuit will be low. Therefore, in order to have a characteristic impedance of 100Ω, the line width of the signal circuit must be made small, and variations in line width will cause variations in characteristic impedance. As a result, reflected resonance noise due to impedance mismatch tends to be absorbed into the electrical signal. When the separation distance is greater than 200 μm, the printed wiring board 2 with electromagnetic shielding film becomes thick and lacks flexibility.

(Flexible printed wiring board)
The flexible printed wiring board 50 is a printed circuit 54 formed by processing the copper foil of a copper-clad laminate into a desired pattern using a known etching method.
The copper-clad laminate is one in which copper foil is attached to one or both sides of the base film 52 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. Examples include things.
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.

The base film 52 is preferably a heat-resistant film, more preferably a polyimide film, a polyetherimide film, a polyphenylene sulfide 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. From a practical point of view, the surface resistance of the base film 52 is preferably 1×10 ¹⁹ Ω/□ or less.
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 more preferably 10 μm or more and 25 μm or less, from the viewpoint of flexibility.

Examples of the copper foil constituting the printed circuit 54 include rolled copper foil, electrolytic copper foil, etc., and rolled copper foil is preferred from the viewpoint of flexibility. The printed circuit 54 is used as a signal circuit, a ground circuit, a ground layer, etc.
The thickness of the copper foil is preferably 1 μm or more and 50 μm or less, more preferably 18 μm or more and 35 μm or less.
The lengthwise ends (terminals) of the printed circuit 54 are not covered with the insulating film 60 or the electromagnetic shielding film 1 and are exposed for soldering, connector connection, component mounting, etc.

(insulating film)
The insulating film 60 (coverlay film) has an adhesive layer (not shown) formed on one side of an insulating film body (not shown) by applying an adhesive, pasting 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. From a practical point of view, the surface resistance of the insulating film body is preferably 1×10 ¹⁹ Ω/□ or less.
As the insulating film body, a film having heat resistance is preferable, a polyimide film, a polyetherimide film, a polyphenylene sulfide film, a liquid crystal polymer film is more preferable, and a polyimide film is even more preferable.
The thickness of the insulating film body is preferably 1 μm or more and 100 μm or less, and more preferably 3 μm or more and 25 μm or less from the viewpoint of flexibility.
Examples of 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 (such as carboxy-modified nitrile rubber) for imparting flexibility.
The thickness of the adhesive layer is preferably 1 μm or more and 100 μm or less, 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 square.

(Other embodiments)
The printed wiring board with an electromagnetic shielding film of this aspect is not limited to the illustrated embodiment.
For example, the flexible printed wiring board 50 may have a ground layer on the back side. Further, the flexible printed wiring board 50 may have the printed circuit 54 on both sides, and the insulating film 60 and the electromagnetic shielding film 1 may be attached to both sides.
Instead of the flexible printed wiring board 50, an inflexible rigid printed circuit board may be used.

<Method for manufacturing printed wiring board with electromagnetic shielding film>
A third aspect of the present invention has a printed wiring board in which a printed circuit is provided on at least one side of the substrate, and an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided, and A printed wiring board with an electromagnetic wave shielding film, in which a printed wiring board with an insulating film in which a through hole is formed and the electromagnetic wave shielding film of the above embodiment are stacked and pressure-bonded so that the insulating film and an anisotropic conductive adhesive layer are in contact with each other. This is a manufacturing method.

The printed wiring board 2 with an electromagnetic shielding film can be manufactured, for example, by a method including the following steps (a) to (d) (see FIG. 3).
Step (a): An insulating film 60 in which a through hole 62 is formed at a position corresponding to the printed circuit 54 is provided on the surface of the flexible printed wiring board 50 on the side where the printed circuit 54 is provided, thereby producing a printed wiring board with an insulating film. The process of obtaining 3.
Step (b): After step (a), the printed wiring board 3 with an insulating film and the electromagnetic shielding film 1 from which the release film 40 has been removed are bonded together so that an anisotropically conductive adhesive layer 24 is formed on the surface of the insulating film 60. The process of stacking them so that they are in contact and crimping them together.
Step (c): After step (b), a step of peeling off the carrier film 30 when the carrier film 30 is no longer needed.
Step (d): A step of main curing the anisotropically conductive adhesive layer 24 between steps (a) and (b) or after step (c), if necessary.
Each step will be described in detail below with reference to FIG.

Step (a):
Step (a) is a step of laminating an insulating film 60 on a flexible printed wiring board 50 to obtain a printed wiring board 3 with an insulating film.
Specifically, first, an insulating film 60 having through holes 62 formed in positions corresponding to the printed circuits 54 is placed 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 to obtain the printed wiring board 3 with the insulating film. 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 permanently cured in step (d).
Adhesion and curing of the adhesive layer is performed, for example, by hot pressing using a press machine (not shown) or the like.

Step (b):
Step (b) is a step of press-bonding the electromagnetic shielding film 1 to the printed wiring board 3 with an insulating film.
Specifically, the electromagnetic shielding film 1 from which the release film 40 has been peeled is placed on the insulating film-attached printed wiring board 3, and the electromagnetic shielding film 1 is bonded by heat pressing or the like. As a result, the anisotropically conductive adhesive layer 24 is bonded to the surface of the insulating film 60, and the anisotropically conductive adhesive layer 24 is pushed into the through hole 62, filling the inside of the through hole 62 and bonding to the printed circuit 54. do. As a result, the anisotropically conductive adhesive layer 24 was reliably adhered to the printed circuit 54 through the through hole 62 of the insulating film 60, and the metal thin film layer 22 was reliably electrically connected to the printed circuit 54. A printed wiring board 2 with an electromagnetic shielding film is obtained.

Adhesion and curing of the anisotropically conductive adhesive layer 24 is performed, for example, by hot pressing using a press (not shown) or the like.
The heat pressing time is preferably 20 seconds or more and 60 minutes or less, more preferably 30 seconds or more and 30 minutes or less. If the hot pressing time is at least the lower limit of the above range, the anisotropically conductive adhesive layer 24 can be easily adhered to the surface of the insulating film 60. If the heat pressing time is less than or equal to the upper limit of the above range, the manufacturing time of the electromagnetic shielding film-equipped printed wiring board 2 can be shortened.

The temperature of the hot press (the temperature of the hot platen of the press machine) is preferably 140°C or more and 190°C or less, more preferably 150°C or more and 175°C or less. If the temperature of the hot press is equal to or higher than the lower limit of the above range, the anisotropically conductive adhesive layer 24 can be easily adhered to the surface of the insulating film 60 and the printed circuit 54. Moreover, the time for heat pressing can be shortened. If the temperature of the hot press is below the upper limit of the above range, deterioration of the electromagnetic shielding film 1, the flexible printed wiring board 50, etc. can be easily suppressed.

The pressure of the hot press is preferably 3 MPa or less, more preferably 0.5 MPa or more and 2.5 MPa or less, and even more preferably 0.1 MPa or more and 2 MPa or less. If the pressure of the hot press is equal to or higher than the lower limit of the above range, the anisotropically conductive adhesive layer 24 will be more reliably bonded to the surface of the insulating film 60 and the printed circuit 54. Moreover, the time for heat pressing can be shortened. If the pressure of the hot press is below the upper limit of the above range, damage to the electromagnetic shielding film 1, the flexible printed wiring board 50, etc. can be suppressed.

Step (c):
Step (c) is a step of peeling off the carrier film 30.
Specifically, when the carrier film is no longer needed, the carrier film 30 is peeled off from the insulating resin layer 10.

Step (d):
Step (d) is a step of main curing the anisotropically conductive adhesive layer 24.
If the heat pressing time in step (b) is a short time of 20 seconds or more and 10 minutes or less, an anisotropic conductive adhesive layer is formed between step (b) and step (c) or after step (c). It is preferable to perform the main curing of 24 times.
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 15 minutes or more and 120 minutes or less, and more preferably 30 minutes or more and 60 minutes or less.
If the heating time is at least the lower limit of the above range, the anisotropically conductive adhesive layer 24 can be sufficiently cured. If the heating time is equal to or less than the upper limit of the above range, the manufacturing time of the electromagnetic shielding film-equipped printed wiring board 2 can be shortened.
The heating temperature (ambient temperature in the oven) is preferably 120°C or more and 180°C or less, more preferably 120°C or more and 150°C or less. If the heating temperature is at least the lower limit of the range, the heating time can be shortened. If the heating temperature is below the upper limit of the above range, deterioration of the electromagnetic shielding film 1, the flexible printed wiring board 50, etc. can be suppressed.

EXAMPLES Hereinafter, the present invention will be explained in more detail by showing examples and comparative examples, but the present invention is not limited to the following examples.

(storage modulus)
The storage modulus was measured using a dynamic viscoelasticity measurement device (RSA II, manufactured by Rheometric Scientific, USA) under the conditions of temperature: 180°C, frequency: 1Hz, and heating rate: 10°C/min.

(Connection resistance)
Regarding a flexible printed wiring board with an electromagnetic shielding film, the connection resistance between the ground of the printed circuit, which is connected to the metal thin film layer through the anisotropic conductive adhesive layer at the through-hole part of the insulating film, and the metal thin film layer. , measured using a digital multimeter.

(Peel strength)
A reinforcing polyimide film having a thickness of 25 μm was thermocompression bonded to the surface of the insulating resin layer of a flexible printed wiring board with an electromagnetic shielding film via a bonding sheet (manufactured by Dexerials, D3410) to prepare a test piece. A chuck of a testing machine (manufactured by Shimadzu Corporation, Autograph AGS-20NX) was attached to the reinforcing polyimide film and the base film of the flexible printed wiring board, and the peeling direction was 180° and the tensile speed was 50 mm/min in accordance with JIS Z 0237:2009. A peel test was conducted under the following conditions to determine the peel strength.

(raw materials)
As a coating material for forming an insulating resin layer, 100 parts by mass of bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 828), 20 parts by mass of a curing agent (manufactured by Showa Denko Co., Ltd., Shoamine X (registered trademark)) A coating material was prepared by dissolving 2 parts by mass of 1 part, 2 parts by mass of 2-ethyl-4-methylimidazole, and 2 parts by mass of carbon black in 200 parts by mass of a solvent (methyl ethyl ketone).
As a carrier film and a release film, a PET film (manufactured by Lintec Corporation, T157, thickness of the release film body: 50 μm, thickness of the release agent layer: 0.1 μm) was prepared.

A flexible printed wiring board with an insulating film was produced as follows.
A copper-clad laminate having a 12.5 μm thick copper foil on the surface of a 25 μm thick polyimide film (base film) was prepared.
An insulating film was prepared in which an adhesive layer was formed on the surface of a 12.5 μm thick polyimide film (insulating film body), and a through hole was formed at a position corresponding to the printed circuit (ground) of a flexible printed wiring board. .
A printed circuit was formed by etching the copper foil of the copper-clad laminate to obtain a flexible printed wiring board. A flexible printed wiring board with an insulating film was obtained by pressure-bonding the flexible printed wiring board and the insulating film using a heat press.

(Example 1)
As a thermosetting conductive adhesive composition, 100 parts by mass of a thermosetting adhesive (epoxy resin (manufactured by DIC, EXA-4816) and 20 parts by mass of a curing agent (manufactured by Ajinomoto Fine-Techno, Inc., PN-23) were used. 6 parts by mass of conductive particles (copper particles with average particle diameter B: 5.02 μm) were dissolved or dispersed in 200 parts by mass of a solvent (methyl ethyl ketone). I prepared something.

A paint for forming an insulating resin layer was applied to the surface of the release agent layer of the carrier film, and heated at 60° C. for 2 minutes to dry and semi-cure the paint to form an insulating resin layer (thickness: 10 μm).
Copper was physically deposited on the surface of the insulating resin layer by electron beam evaporation to form a metal thin film layer (deposited film, thickness: 70 nm).
A thermosetting conductive adhesive composition is applied to the surface of the metal thin film layer using a die coater, and the solvent is evaporated to form a B stage. A: 3 μm, copper particles: 5% by mass) were formed.
A release film was attached to the surface of the anisotropically conductive adhesive layer to obtain an electromagnetic shielding film as shown in FIG. 1.

Layer the electromagnetic shielding film with the release film peeled off on the flexible printed wiring board with the insulating film, and use a hot press machine (manufactured by Orihara Seisakusho Co., Ltd., G-12) to heat the platen temperature: 170°C and pressure: 2MPa for 120 seconds. An anisotropically conductive adhesive layer was temporarily attached to the surface of the insulating film by hot pressing. The flexible printed wiring board to which the electromagnetic shielding film has been temporarily bonded is heated at 160°C for 1 hour using a high-temperature incubator (HT210, manufactured by Kusumoto Kasei Co., Ltd.) to fully cure the anisotropically conductive adhesive layer. A flexible printed wiring board with an electromagnetic shielding film was obtained. The results are shown in Table 1.

(Examples 2 to 18, Comparative Examples 1 to 4)
As shown in Table 1, Example 1 except that one or more of the adhesive thickness A, the average particle diameter B of the copper particles, and the proportion of copper particles in the anisotropically conductive adhesive layer was changed. In the same manner as above, an electromagnetic shielding film and a flexible printed wiring board with an electromagnetic shielding film were obtained. The results are shown in Table 1.

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

1 Electromagnetic shielding film,
2 Printed wiring board with electromagnetic shielding film,
3 Printed wiring board with insulation film,
10 insulating resin layer,
20 conductive layer,
22 metal thin film layer,
24 Anisotropic conductive adhesive layer,
24a thermosetting adhesive,
24b conductive particles,
30 carrier film,
32 carrier film body,
34 mold release agent layer,
40 release film,
42 Release film body,
44 mold release agent layer,
50 Flexible printed wiring board,
52 base film,
54 printed circuit,
60 Insulating film,
62 Through hole.

Claims (5)

an insulating resin layer;
a metal thin film layer;
an anisotropic conductive adhesive layer containing an adhesive and conductive particles,
The thickness A of the adhesive in the anisotropic conductive adhesive layer and the average particle diameter B of the conductive particles satisfy the relationship of 1.62A ≦B≦ 1.93A ,
An electromagnetic shielding film, wherein the thickness A of the adhesive is 5.2 μm or more and 6.2 μm or less . The electromagnetic shielding film according to claim 1, wherein the proportion of the conductive particles is 5% by mass or more and 50% by mass or less of 100% by mass of the anisotropically conductive adhesive layer. a printed wiring board having a printed circuit on at least one side of the board;
an insulating film adjacent to the surface of the printed wiring board on which the printed circuit is provided;
The anisotropically conductive adhesive layer is adjacent to the insulating film, and the anisotropically conductive adhesive layer is electrically connected to the printed circuit through a through hole formed in the insulating film. A printed wiring board with an electromagnetic shielding film, comprising the electromagnetic shielding film according to 1 or 2. A printed wiring board having a printed circuit provided on at least one side of the substrate, and an insulating film adjacent to the side of the printed wiring board on which the printed circuit is provided, and a through hole is formed in the insulating film. A printed wiring with an electromagnetic shielding film, which comprises stacking and pressing a printed wiring board with an insulating film and the electromagnetic shielding film according to claim 1 or 2 so that the insulating film and the anisotropically conductive adhesive layer are in contact with each other. Method of manufacturing the board. The method for manufacturing a printed wiring board with an electromagnetic shielding film according to claim 4, wherein the printed wiring board with an electromagnetic shielding film is pressure-bonded to the printed wiring board with an electromagnetic shielding film at a pressure of 3 MPa or less.

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