TW201934697A - Electromagnetic wave shielding film capable of easily peeling off a transfer film without damaging the insulating protective layer - Google Patents

Abstract

Provided is an electromagnetic wave shielding film in which a transfer film is easily peeled off. The electromagnetic wave shielding film of the present invention as the solution includes: an insulating protective layer; the transfer film provided on the surface of the insulating protective layer; and a conductive adhesive layer disposed at the position of the insulating protective layer opposite to the transfer film. The maximum valley depth (Sv) of the surface on the side of the insulating protective layer of the transfer film is 1 [mu]m or more and 6 [mu]m or less, and the maximum height (Sz) is 2 [mu]m or more and 10 [mu]m or less.

Description

Electromagnetic wave shielding film

The present invention relates to an electromagnetic wave shielding film.

BACKGROUND In order to protect electronic circuits from electromagnetic waves, an electromagnetic wave shielding film is used. The electromagnetic wave shielding film has a conductive adhesive layer and an insulating protective layer. Generally, an electromagnetic wave shielding film is manufactured by sequentially forming an insulating protection layer and a conductive adhesive layer on the surface of a substrate film. The base film is formed by bonding the electromagnetic wave shielding film to the printed wiring board and removing it before the reflow step. At this time, the base film functions as a transfer film whose surface state can be transferred to the insulating protective layer. The base film also functions as a protective film to protect the insulating protective layer until the electromagnetic wave shielding film is adhered to the printed wiring board.

In order to make the surface of the insulating protective layer a matte surface, unevenness is usually provided on the surface of the transfer film. By providing unevenness, the adhesion between the transfer film and the insulating protective layer becomes high, and the force required to peel the transfer film becomes large. In addition, when an electromagnetic wave shielding film is bonded to a printed wiring board, a pressure of several MPa is usually applied at a temperature of about 150 ° C to 200 ° C. When exposed to such temperatures and pressures, peeling of the transfer film becomes more difficult, and the transfer film may break.

In order to prevent cracking at the time of peeling, a method for making the transfer film itself difficult to crack has been studied (for example, refer to Patent Documents 1 and 2).

Prior art documents Patent documents Patent document 1: Japanese Patent Application Laid-Open No. 2015-185659 Patent document 2: Japanese Patent Application Laid-Open No. 2016-97522

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, even if the transfer film itself is difficult to crack, if a large force is required for peeling, the productivity will be lowered. In addition, it may cause damage to the insulating protective layer side. In order to make the transfer film easily peelable, it is desirable to control the interaction between the transfer film and the insulating protective layer.

An object of the present invention is to realize an electromagnetic wave shielding film in which a transfer film is easily peeled.

Means for Solving the Problems One aspect of the electromagnetic wave shielding film of the present invention includes: an insulating protective layer; a transfer film provided on the surface of the insulating protective layer; and a conductive adhesive layer provided on the insulating protective layer. The side opposite to the transfer film; the maximum valley depth (Sv) of the surface on the insulating protective layer side of the transfer film is 1 μm or more and 6 μm or less, and the maximum height (Sz) is 2 μm or more and 10 μm or less.

In one aspect of the electromagnetic wave shielding film, the variation coefficient of the maximum valley depth (Sv) and the variation coefficient of the maximum height (Sz) on the surface of the insulating protective layer side of the transfer film can be set to 0.2 or less.

Advantageous Effects of Invention According to the electromagnetic wave shielding film of the present invention, the transfer film can be easily peeled and productivity can be improved.

The form for implementing the invention is shown in FIG. 1. The electromagnetic wave shielding film of this embodiment includes: an insulating protective layer 112; a transfer film 115 provided on the surface of the insulating protective layer 112; The conductive adhesive layer 111 on the opposite side of the transfer film 115. Furthermore, as shown in FIG. 2, a shielding layer 113 may be provided between the insulating protective layer 112 and the conductive adhesive layer 111.

The present inventors have found that by setting the maximum valley depth (Sv) on the surface of the insulating protective layer 112 side of the transfer film 115 to be 6 μm or less, preferably 5 μm or less, and setting the maximum height (Sz) to 10 μm Below, preferably 9 μm or less, a transfer film 115 that can be easily peeled off can be formed.

On the other hand, it was found that there is a film that is difficult to peel even if the arithmetic mean height (Sa) is small. The reason for this may be that even if the average level of unevenness is the same, as long as there are extremely small pinpoints of deep valleys or high mountains, the adhesion to the part will increase, and peeling will become difficult. Therefore, it is important to control Sv and Sz of the transfer film 115. The Sa, Sv, and Sz of the transfer film 115 can be measured by the methods described in the examples.

From the viewpoint of facilitating peeling, the smaller the maximum valley depth on the surface of the insulating protective layer 112 side of the transfer film 115 is, the better, but from the viewpoint of making the surface of the insulating protective layer 112 a matte surface. From the viewpoint of preventing the transfer film 115 from peeling off before it is fixed to the printed wiring board, Sv is 1 μm or more, preferably 2 μm or more, and Sz is 2 μm or more, preferably 3 μm or more.

From the viewpoint of easy peeling, the peeling strength of the transfer film 115 is preferably 5.0 N / 50 mm or less, and preferably 1.5 N / 50 mm or less. From the viewpoint of preventing the transfer film 115 from peeling before use, peeling The strength is preferably 0.2N / 50mm or more, and more preferably 0.5N / 50mm or more. In addition, the peeling strength of the transfer film 115 can be measured by the method shown in an Example.

From the viewpoint of making peeling easier, the coefficient of variation of Sv and the coefficient of variation (CV) of Sz on the surface of the insulating protective layer 112 side of the transfer film 115 are preferably 0.2 or less, and more preferably 0.15 or less. The coefficient of variation referred to here is a value obtained from the arithmetic mean and standard deviation of 10 points as shown in the examples.

From the viewpoint of making peeling easier, it is desirable to control parameters other than Sv and Sz that represent surface properties. For example, the kurtosis (Sku) is preferably 2.0 or more, preferably 3.0 or more, and preferably 8.5 or less, and more preferably 7.5 or less. The minimum autocorrelation length (Sal) is preferably 7.5 μm or more, preferably 8.5 μm or more, and preferably 20.0 μm or less, and preferably 15.0 or less. The aspect ratio (Str) of the surface texture is preferably 0.55 or more, more preferably 0.60 or more, and more preferably 0.75 or less. The protruding valley height (Svk) is preferably 0.20 or more, preferably 0.25 or more, and preferably 0.75 or less, and more preferably 0.70 or less. The load area ratio (Smr2) separating the protruding valley portion from the core portion is preferably 90.0% or more, and more preferably 94.0% or more. These parameters showing surface properties can also be measured by the methods shown in the examples.

The material of the transfer film 115 is not particularly limited, and polyester, polyolefin, polyimide, polyethylene naphthalate, or polyphenylene sulfide can be used. The thickness of the transfer film 115 is not particularly limited, but from the viewpoint of facilitating peeling, it is preferably 25 μm or more and 100 μm or less.

In order to make Sv and Sz predetermined values, at least one surface of the transfer film 115 may be sandblasted or the like. In addition, by including fine particles, Sv and Sz can be set to predetermined values. The microparticles added to the transfer film 115 are not particularly limited, and examples thereof include amorphous silicon dioxide (colloidal silicon dioxide), silicon dioxide, talc, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, Inorganic particles such as lithium phosphate, calcium phosphate, magnesium phosphate, alumina, carbon black, titanium dioxide, kaolin and synthetic zeolites; and organic particles such as cross-linked polystyrene particles and cross-linked acrylic particles.

A release agent layer (not shown) may be provided between the transfer film 115 and the insulating protection layer 112. The release agent layer can be formed by applying a silicon-based or non-silicon-based release agent to a surface on the insulating protective layer 112 side of the transfer film 115. When the release agent layer is formed, its thickness may be about several μm to about ten μm.

In this embodiment, the insulating protective layer 112 is not particularly limited as long as it has sufficient insulation, can protect the conductive adhesive layer 111, and if necessary, the shielding layer 113. For example, a thermoplastic resin, a thermosetting resin, or It is made of an active energy ray-curable resin or the like.

The thermoplastic resin is not particularly limited, and a styrene resin, a vinyl acetate resin, a polyester resin, a polyethylene resin, a polypropylene resin, a diimide resin, or an acrylic resin can be used. The thermosetting resin is not particularly limited, and a phenol-based resin, an epoxy-based resin, a urethane-based resin, a melamine-based resin, a polyamide-based resin, or an alkyd-based resin can be used. The active energy ray-curable resin is not particularly limited, and for example, a polymerizable compound having at least two (meth) acrylic fluorenyloxy groups in a molecule can be used. The protective layer may be formed of a single material, or may be formed of two or more materials.

The insulating protective layer 112 is not limited to a coloring agent, and may include a hardening accelerator, a tackifier, an antioxidant, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, One or more of a viscosity modifier and an anti-caking agent.

The insulating protective layer 112 may be a laminate of two or more layers having different physical properties such as material, hardness, or elastic modulus. For example, if a laminated body with an outer layer having a lower hardness and an inner layer having a higher hardness is formed, since the outer layer has a buffering effect, the step of heating and pressing the electromagnetic wave shielding film 101 on the printed wiring board 102 can be relaxed to the shielding layer 113 pressure. Therefore, it is possible to prevent the shield layer 113 from being damaged due to the height difference provided on the printed wiring board 102.

The insulating protective layer 112 can be formed by coating the surface of the transfer film 115 with a composition for an insulating protective layer. The composition for an insulating protective layer can be prepared by adding an appropriate amount of a solvent to the resin for an insulating protective layer, for example.

The thickness of the insulating protective layer 112 is not particularly limited, and may be appropriately set as necessary, but it is preferably set to 1 μm or more, preferably 4 μm or more, and preferably 20 μm or less, preferably 10 μm or less, and more preferably 5 μm or less. By setting the thickness of the insulating protective layer 112 to 1 μm or more, the conductive adhesive layer 111 and the shielding layer 113 can be sufficiently protected. By setting the thickness of the insulating protective layer 112 to 20 μm or less, the elastic modulus and the elongation at break of the electromagnetic wave shielding film 101 can be easily set to predetermined values.

When the shielding layer 113 is provided, the shielding layer 113 can be formed by a metal foil, a vapor-deposited film, a conductive filler, or the like.

The metal foil is not particularly limited, and it can be made of any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, and zinc, or an alloy containing two or more types.

The thickness of the metal foil is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1.0 μm or more. If the thickness of the metal foil is 0.5 μm or more, when a high-frequency signal of 10 MHz to 100 GHz is transmitted to the shielded printed wiring board, the amount of attenuation of the high-frequency signal can be suppressed. The thickness of the metal foil is preferably 12 μm or less, preferably 10 μm or less, and more preferably 7 μm or less. When the thickness of the metal layer is 12 μm or less, the judgment elongation of the shielding film can be improved while reducing the cost of raw materials.

The vapor-deposited film is not particularly limited, and can be formed by vapor-depositing nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and the like. For the evaporation, an electrolytic plating method, an electroless plating method, a sputtering method, an electron beam evaporation method, a vacuum evaporation method, a chemical vapor deposition (CVD) method, or a metal organic chemical vapor deposition (MOCVD) method can be used. .

The thickness of the vapor-deposited film is not particularly limited, but is preferably 0.05 μm or more, and more preferably 0.1 μm or more. When the thickness of the metal vapor-deposited film is 0.05 μm or more, the shielding property of the electromagnetic wave shielding film in the shielded printed wiring board is excellent. The thickness of the metal deposited film is preferably less than 0.5 μm, and more preferably less than 0.3 μm. When the thickness of the metal vapor-deposited film is less than 0.5 μm, the electromagnetic wave shielding film is excellent in bending resistance, and the shielding layer can be prevented from being damaged due to the height difference provided on the printed wiring board.

In the case of a conductive filler, the shielding layer 113 can be formed by applying a solvent prepared with a conductive filler on the surface of the insulating protective layer 112 and drying it. As the conductive filler, a metal filler, a metal-coated resin filler, a carbon filler, and a mixture thereof can be used. As for the metal filler, copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder can be used. These metal powders can be produced by electrolytic method, atomization method, and reduction method. Examples of the shape of the metal powder include a spherical shape, a small plate shape, a fibrous shape, and a dendritic shape.

In this embodiment, the thickness of the shielding layer 113 may be appropriately selected according to the required electromagnetic shielding effect and repeated bending and sliding resistance. When the shielding layer 113 is a metal foil, it is considered from the viewpoint of ensuring the elongation at break. The thickness of the shielding layer 113 should be set to 12 μm or less.

In this embodiment, the conductive adhesive layer 111 includes a resin component such as a thermoplastic resin and a thermosetting resin, and a conductive filler.

When the conductive adhesive layer 111 contains a thermoplastic resin, the thermoplastic resin may be, for example, a styrene resin, a vinyl acetate resin, a polyester resin, a polyethylene resin, a polypropylene resin, a fluorene resin, or Acrylic resin, etc. These resins may be used singly or in combination of two or more kinds.

When the conductive adhesive layer 111 contains a thermosetting resin, the thermosetting resin can be, for example, a phenol-based resin, an epoxy-based resin, a urethane-based resin, a melamine-based resin, a polyamide-based resin, and an alcohol. Acid-based resins, etc. The active energy ray-curable composition is not particularly limited, and for example, a polymerizable compound having at least two (meth) acryloxy groups in a molecule can be used. These compositions may be used singly or in combination of two or more kinds.

The thermosetting resin includes, for example, a first resin component having a reactive first functional group and a second resin component that reacts with the first functional group. The first functional group can be, for example, an epoxy group, amidino group, or a hydroxyl group. The second functional group may be selected according to the first functional group. For example, when the first functional group is an epoxy group, the second functional group may be a hydroxyl group, a carboxyl group, an epoxy group, an amine group, or the like. Specifically, for example, when the first resin component is an epoxy resin, as the second resin component, epoxy-modified polyester resin, epoxy-modified polyamine resin, and epoxy-modified acrylic can be used. Resin, epoxy-modified polyurethane polyurea resin, carboxy-modified polyester resin, carboxy-modified polyamine resin, carboxy-modified acrylic resin, carboxy-modified polyurethane polyurea resin And urethane modified polyester resin. Among these, a carboxyl modified polyester resin, a carboxyl modified polyamine resin, a carboxyl modified polyurethane polyurea resin, and a urethane modified polyester resin are preferred. When the first resin component is a hydroxyl group, the second resin component can be used: epoxy-modified polyester resin, epoxy-modified polyamine resin, epoxy-modified acrylic resin, epoxy-modified Polyurethane polyurea resin, carboxyl modified polyester resin, carboxyl modified polyamido resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin, and urethane modified High quality polyester resin. Among these, a carboxyl modified polyester resin, a carboxyl modified polyamine resin, a carboxyl modified polyurethane polyurea resin, and a urethane modified polyester resin are preferred.

The thermosetting resin may contain a curing agent for promoting a thermosetting reaction. When the thermosetting resin has a first functional group and a second functional group, the curing agent can be appropriately selected depending on the types of the first functional group and the second functional group. When the first functional group is an epoxy group and the second functional group is a hydroxyl group, an imidazole-based hardener, a phenol-based hardener, or a cationic hardener can be used as the hardener. These hardeners may be used singly or in combination of two or more kinds. In addition, the optional component may include a defoamer, an antioxidant, a viscosity modifier, a diluent, an anti-settling agent, a leveling agent, a coupling agent, a colorant, a flame retardant, and the like.

The conductive filler is not particularly limited, and examples thereof include metal fillers, metal-coated resin fillers, carbon fillers, and mixtures thereof. Examples of the metal filler include copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be produced by an electrolytic method, an atomization method, or a reduction method. Among them, any one of silver powder, silver-coated copper powder, and copper powder is preferred.

From the viewpoint that the fillers are in contact with each other, the average particle diameter of the conductive filler is preferably 1 μm or more, more preferably 3 μm or more, and preferably 50 μm or less, and more preferably 40 μm or less. The shape of the conductive filler is not particularly limited, and may be spherical, platelet-shaped, dendritic, or fibrous.

The content of the conductive filler can be appropriately selected according to the application, and it is preferably 5 mass% or more, more preferably 10 mass% or more, and more preferably 95 mass% or less, and more preferably 90 mass% or less in the total solid content. From the viewpoint of landfillability, it is preferably 70% by mass or less, and more preferably 60% by mass or less. When anisotropic conductivity is to be achieved, it is preferably 40% by mass or less, and more preferably 35% by mass or less.

The conductive adhesive layer 111 can be formed by, for example, applying a composition for a conductive adhesive layer to the insulating protective layer 112 or the shielding layer 113 formed on the insulating protective layer 112. The composition for a conductive adhesive layer can be prepared by adding an appropriate amount of a solvent to the resin and a filler for a conductive adhesive layer.

From the viewpoint of controlling the landfilling property, the thickness of the conductive adhesive layer 111 is preferably 1 μm to 50 μm.

Moreover, a peelable protective film may be laminated on the surface of the conductive adhesive layer 111 as needed.

As shown in FIG. 3, the electromagnetic wave shielding film 101 of this embodiment can be combined with a printed wiring board 102 to form a shielded wiring board 103. The electromagnetic wave shielding film 101 may be one having a shielding layer 113.

The printed wiring board 102 includes, for example, a printed circuit including a base member 122 and a ground circuit 125 provided on the base member 122. An insulating film 121 is adhered to the base member 122 through an adhesive layer 123. An opening is provided in the insulating film 121 to expose the ground circuit 125. A surface layer such as a gold plating layer may be provided on the exposed portion of the ground circuit 125. The printed wiring board 102 may be a flexible substrate or a rigid substrate.

When the electromagnetic wave shielding film 101 is attached to the printed wiring board 102, the electromagnetic wave shielding film 101 is disposed on the printed wiring board 102 such that the conductive adhesive layer 111 is positioned on the opening. Then, the electromagnetic wave shielding film 101 and the printed wiring board 102 are sandwiched from above and below by two heating plates (not shown) heated to a predetermined temperature (for example, 120 ° C.) and pressurized with a predetermined pressure (for example, 0.5 MPa). Short time (for example, 5 seconds). Thereby, the electromagnetic wave shielding film 101 is temporarily fixed to the printed wiring board 102.

Then, the temperature of the two heating plates is set to a predetermined temperature (for example, 170 ° C.) which is higher than the temperature at the time of the temporary fixation, and the pressure is applied for a predetermined time (for example, 30 minutes) at a predetermined pressure (for example, 3 MPa). Thereby, the electromagnetic wave shielding film 101 can be fixed to the printed wiring board 102. When the conductive adhesive layer 111 is fully buried in the opening during the pressurization, the strength and conductivity required for the electromagnetic wave shielding film 101 can be achieved.

After the electromagnetic wave shielding film 101 is fixed to the printed wiring board 102, the transfer film 115 is peeled. Then, solder reflow for mounting the parts is performed. Since the electromagnetic wave shielding film 101 of this embodiment can be easily peeled off after the electromagnetic wave shielding film 101 is fixed to the printed wiring board 102, the production efficiency can be improved.

[Example]
Hereinafter, the electromagnetic wave shielding film of the present invention will be described in more detail using examples. The following examples are illustrative and are not intended to limit the present invention.

＜ Production of electromagnetic wave shielding film ＞
A release agent is applied to the surface of a predetermined transfer film. On the surface of the transfer film to which the release agent has been applied, a composition for an insulating protective layer is applied using a wire rod, and then heated and dried to form an insulating protective layer. Then, the composition for a conductive adhesive layer was coated on the insulating protective layer with a wire rod, and then dried at 100 ° C. for 3 minutes to prepare an electromagnetic wave shielding film.

The composition for an insulating protective layer has a two-layer structure: a hard coating layer of a polyester-based transparent resin having a thickness of 2 μm, and a soft coating layer of an epoxy-based black resin containing carbon black having a thickness of 3 μm. The composition for a conductive adhesive layer is set such that dendritic silver-coated copper powder having an average particle diameter of 5 μm is added as conductive particles to an epoxy resin containing a phosphorus-based flame retardant. The thickness of the conductive adhesive layer was set to 15 μm.

＜ Measurement of surface properties ＞
The parameters of the surface properties were measured in accordance with ISO25178 using a laser microscope (VK-X210, manufactured by Keyence Corporation, lens magnification: 50 times). The measurement was performed on the surface of the transfer film which was cut out to 5.0 cm × 5.0 cm and was not used yet to form an insulating protective layer. The measurement was performed at arbitrary 10 positions in the plane, and the arithmetic average value was used as the measurement value. In addition, a standard deviation (SD) and a coefficient of variation (CV) were calculated.

<Measurement of peeling strength>
Using a press, the electromagnetic wave shielding film was pressurized under conditions of temperature: 170 ° C., time: 30 minutes, and pressure: 2 to 3 MPa. After the electromagnetic wave shielding film was returned to normal temperature, the peeling strength of the transfer film was measured on the surface peeling film using a peeling strength tester ((share) PALMEC, PFT50S). The measurement was performed under the conditions of normal temperature, a stretching speed of 1000 mm / min, and a peeling angle of 170 °. The measurement system was performed 10 times, and the minimum value, the maximum value, and the average value were calculated.

(Example 1)
As the transfer film, a PET film having a thickness of 50 μm was used. The surface of the insulating protective layer after peeling the transfer film becomes a matte surface. Sv was 3.1 μm, Sz was 8.0 μm, and Sa was 0.69 μm on the insulating protective layer formation surface of the transfer film. The coefficient of variation of Sv is 0.15, and the coefficient of variation of Sz is 0.02. The minimum value of the peeling strength was 0.51 N / 50 mm, the maximum value was 0.75 N / 50 mm, and the average value was 0.63 N / 50 mm.

(Example 2)
As the transfer film, a PET film having a thickness of 50 μm was used. The surface of the insulating protective layer after peeling the transfer film becomes a matte surface. Sv was 2.5 μm, Sz was 6.6 μm, and Sa was 0.41 μm on the insulating protective layer formation surface of the transfer film. The coefficient of variation of Sv is 0.12, and the coefficient of variation of Sz is 0.08. The minimum value of the peeling strength was 0.60 N / 50 mm, the maximum value was 0.76 N / 50 mm, and the average value was 0.68 N / 50 mm.

(Example 3)
As the transfer film, a PET film having a thickness of 50 μm was used. The surface of the insulating protective layer after peeling the transfer film becomes a matte surface. Sv was 5.9 μm, Sz was 9.6 μm, and Sa was 0.69 μm on the insulating protective layer formation surface of the transfer film. The coefficient of variation of Sv is 0.07, and the coefficient of variation of Sz is 0.09. The minimum value of the peel strength was 0.98 N / 50 mm, the maximum value was 1.50 N / 50 mm, and the average value was 1.25 N / 50 mm.

(Comparative example 1)
As the transfer film, a PET film having a thickness of 50 μm was used. The surface of the insulating protective layer after peeling the transfer film becomes a matte surface. Sv was 6.8 μm, Sz was 11.4 μm, and Sa was 0.48 μm on the insulating protective layer formation surface of the transfer film. The coefficient of variation of Sv is 0.43, and the coefficient of variation of Sz is 0.40. The minimum value of the peeling strength was 7.0 N / 50 mm, and the maximum value exceeded 10 N / 50 mm, and measurement was impossible.

(Comparative example 2)
As the transfer film, a PET film having a thickness of 50 μm was used. The surface of the insulating protective layer after peeling the transfer film becomes a glossy surface. Sv was 0.8 μm, Sz was 1.3 μm, and Sa was 0.06 μm on the insulating protective layer formation surface of the transfer film. The coefficient of variation of Sv is 0.23, and the coefficient of variation of Sz is 0.13. The minimum value of the peeling strength was 0.08 N / 50 mm, the maximum value was 0.15 N / 50 mm, and the average value was 0.10 N / 50 mm.

Table 1 summarizes the results of the examples and comparative examples. In addition to Sv and Sz, it also describes the kurtosis (Sku), the minimum autocorrelation length (Sal), the aspect ratio (Str) of the surface texture, the height of the protruding valley (Svk), and the separation of the protruding valley from the core. Of the load area ratio (Smr2).

[Table 1]

INDUSTRIAL APPLICABILITY The electromagnetic wave shielding film of the present invention can be easily peeled off from the transfer film and can improve productivity.

101‧‧‧ electromagnetic wave shielding film

102‧‧‧printed wiring board

103‧‧‧shielded wiring substrate

111‧‧‧ conductive adhesive layer

112‧‧‧Insulation protective layer

113‧‧‧Shield

115‧‧‧ transfer film

121‧‧‧ insulating film

122‧‧‧ base member

123‧‧‧Adhesive layer

125‧‧‧ ground circuit

FIG. 1 is a sectional view showing an electromagnetic wave shielding film according to an embodiment.

FIG. 2 is a cross-sectional view showing a modified example of the electromagnetic wave shielding film.

3 is a cross-sectional view showing a shielded printed wiring board using an electromagnetic wave shielding film according to an embodiment.

Claims (2)

An electromagnetic wave shielding film comprising: Insulation protection A transfer film is provided on the surface of the aforementioned insulating protective layer; and The conductive adhesive layer is disposed on the opposite side of the insulating protective layer from the transfer film; A maximum valley depth (Sv) of the surface on the side of the insulating protective layer of the transfer film is 1 μm or more and 6 μm or less, and a maximum height (Sz) is 2 μm or more and 10 μm or less. For example, the electromagnetic wave shielding film of claim 1, wherein the coefficient of variation of the maximum valley depth (Sv) and the coefficient of variation of the maximum height (Sz) on the surface of the insulating protective layer side of the transfer film are 0.2 or less.