KR20190100006A - Electromagnetic wave shield film - Google Patents

Abstract

The objective of the present invention is to provide an electromagnetic wave shield film which can easily separate a transfer film. To this end, the electromagnetic wave shield film comprises: an insulation protective layer (112); the transfer film (115) installed on the surface of the insulation protective layer (112); and a conductive adhesive layer (111) installed on the opposite side with the transfer film (115) of the insulation protective layer (112). The surface of the insulation protective layer (112) side of the transfer film (115) has the maximum valley depth (Sv) of 1 μm or more and 6 μm or less, and the maximum height (Sz) of 2 μm or more and 10 μm or less.

Description

Electromagnetic shielding film {ELECTROMAGNETIC WAVE SHIELD FILM}

The present disclosure relates to an electromagnetic wave shielding film.

In order to protect an electronic circuit from electromagnetic waves, the electromagnetic wave shielding film is used. The electromagnetic wave shielding film has a conductive adhesive layer and an insulating protective layer. It is common to manufacture an electromagnetic wave shielding film by forming an insulation protective layer and a conductive adhesive layer in order on the surface of a base film. The base film is removed before the reflow step after the electromagnetic shielding film is adhered to the printed wiring board. In this case, the base film functions as a transfer film whose surface state is transferred to the insulating protective layer. Moreover, it also functions as a protective film which protects an insulating protective layer until an electromagnetic wave shielding film adheres to a printed wiring board.

In order to make the surface of an insulating protective layer a matte surface, it is common to provide an unevenness | corrugation on the surface of a transfer film. By providing the unevenness, the adhesion between the transfer film and the insulating protective layer increases, and the force required when peeling off the transfer film increases. In addition, when bonding an electromagnetic wave shielding film to a printed wiring board, it is common to apply the pressure of several MPa at the temperature of about 150 degreeC-about 200 degreeC. When exposed to such temperature and pressure, peeling of a transfer film will become more difficult and a transfer film may break.

In order to prevent fracture at the time of peeling, making it difficult to tear the transfer film itself is examined (for example, refer patent document 1 and 2).

Japanese Patent Application Laid-Open No. 2015-185659 Japanese Patent Application Laid-Open No. 2016-97522

However, even if the transfer film itself becomes difficult to be torn, productivity is reduced if a large force is required at the time of peeling. Moreover, there exists a possibility that the side of an insulating protective layer may be damaged. In order to be able to peel easily a transfer film, it is desired to control interaction of a transfer film and an insulating protective layer.

The subject of this indication is making it possible to implement the electromagnetic wave shielding film which is easy to peel off a transfer film.

One aspect of the electromagnetic wave shielding film of the present disclosure includes an insulation protective layer, a transfer film provided on the surface of the insulation protection layer, and a conductive adhesive layer provided on the side opposite to the transfer film of the insulation protection layer, and the insulation protection of the transfer film. As for the surface of a layer side, maximum valley depth Sv is 1 micrometer or more and 6 micrometers or less, and maximum height Sz is 2 micrometers or more and 10 micrometers or less.

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

According to the electromagnetic wave shielding film of this indication, peeling of a transfer film becomes easy and productivity can be improved.

1 is a cross-sectional view showing an electromagnetic wave shielding film according to one embodiment.
It is sectional drawing which shows the modification of an electromagnetic wave shielding film.
It is sectional drawing which shows the shielding printed wiring board using the electromagnetic wave shielding film which concerns on one Embodiment.

As shown in FIG. 1, the electromagnetic wave shielding film of the present embodiment includes an insulating protective layer 112, a transfer film 115 provided on the surface of the insulating protective layer 112, and a transfer film of the insulating protective layer 112. The conductive adhesive layer 111 provided on the opposite side to 115 is provided. 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 set the maximum bone depth Sv at the surface of the transfer film 115 at the side of the insulating protective layer 112 to 6 µm or less, preferably 5 µm or less, and the maximum height Sz to 10 µm or less. It turned out that it becomes the transfer film 115 which can be peeled easily by setting it as 9 micrometers or less preferably.

On the other hand, even if the arithmetic mean height Sa was small, it discovered that the film which was difficult to peel exists. It is considered that even if the average value is the same as the unevenness, if there is a deep valley or a high acid at the pinpoint, the adhesiveness becomes high at that portion, and the peeling becomes difficult. For this reason, it becomes important to control Sv and Sz of the transfer film 115. And Sa, Sv, and Sz of the transfer film 115 can be measured by the method demonstrated in an Example.

From the viewpoint of facilitating peeling, it is preferable that the maximum bone depth at the surface on the side of the insulating protective layer 112 of the transfer film 115 is small, but from the viewpoint and printing 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 being fixed to the 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.

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

From the viewpoint of making the peeling easier, the variation coefficient of Sv and the variation coefficient 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 It may be 0.15 or less. The variation coefficient here is the value calculated | required from the arithmetic mean and standard deviation of ten points as shown in the Example.

Moreover, it is preferable to also control the parameter which shows surface characteristics other than Sv and Sz from a viewpoint of making peeling easier. For example, kurtosis (Sku) becomes like this. Preferably it is 2.0 or more, More preferably, it is 3.0 or more, Preferably it is 8.5 or less, More preferably, it is 7.5 or less. Minimum autocorrelation length Sal becomes like this. Preferably it is 7.5 micrometers or more, More preferably, it is 8.5 micrometers or more, Preferably it is 20.0 micrometers or less, More preferably, it is 15.0 or less. The aspect ratio Str of surface property becomes like this. Preferably it is 0.55 or more, More preferably, it is 0.60 or more, Preferably it is 0.75 or less. Protrusion valley height Svk becomes like this. Preferably it is 0.20 or more, More preferably, it is 0.25 or more, Preferably it is 0.75 or less, More preferably, it is 0.70 or less. The loading area ratio Smr2 separating the protruding valleys and the core portion is preferably 90.0% or more, and more preferably 94.0% or more. The parameter which shows this surface property can also be measured by the method shown in an Example.

The material of the transfer film 115 is not specifically limited, Polyester, polyolefin, polyimide, polyethylene naphthalate, polyphenylene sulfide, etc. can be used. Although the thickness of the transfer film 115 is not specifically limited, From a viewpoint of making peeling easy, Preferably it is 25 micrometers or more, Preferably it is 100 micrometers or less.

At least one surface of the transfer film 115 may be subjected to sandblasting treatment or the like in order to set Sv and Sz to predetermined values. Moreover, Sv and Sz can also be made into a predetermined value by containing microparticles | fine-particles. The fine particles added to the transfer film 115 are not particularly limited and include, for example, amorphous silica (colloidal silica), silica, talc, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, and phosphoric acid. Inorganic particles such as calcium, magnesium phosphate, alumina, carbon black, titanium dioxide, kaolin, and synthetic zeolites, and organic particles such as crosslinked polystyrene particles, and crosslinked acrylic particles can be used.

A release agent layer (not shown) can be provided between the transfer film 115 and the insulating protective layer 112. A mold release agent layer can be formed by apply | coating a silicone type or non-silicone mold release agent to the surface of the insulating protective layer 112 side of the transfer film 115. FIG. When forming a mold release agent layer, the thickness can be about several micrometers-about tens micrometers.

In the present embodiment, the insulating protective layer 112 is not particularly limited as long as it has sufficient insulating properties and can protect the conductive adhesive layer 111 and the shielding layer 113 when necessary, for example, a thermoplastic resin. , Thermosetting resin, active energy ray curable resin, or the like can be formed.

The thermoplastic resin is not particularly limited, but styrene resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, imide resin, acrylic resin or the like can be used. Although it does not specifically limit as a thermosetting resin, A phenol resin, an epoxy resin, a urethane resin, melamine resin, polyamide resin, alkyd resin, etc. can be used. Although it does not specifically limit as active energy ray curable resin, For example, the polymeric compound etc. which have at least two (meth) acryloyloxy group in a molecule | numerator can be used. The protective layer may be formed of a single material or may be formed of two or more kinds of materials.

The insulating protective layer 112 is not limited to a colorant, but a curing accelerator, a tackifier, an antioxidant, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, and a viscosity, as necessary. One or more of a regulator, an antiblocking agent, etc. may be contained.

The insulating protective layer 112 may be a laminate of two or more layers having different materials or physical properties such as hardness or elastic modulus. For example, when the outer layer has a cushioning effect when the laminate is formed of an outer layer having a low hardness and an inner layer having a high hardness, the shielding layer (in the step of heating and pressing the electromagnetic shielding film 101 to the printed wiring board 102) Pressure to 113) can be alleviated. For this reason, it can suppress that the shielding layer 113 is destroyed by the step provided in the printed wiring board 102. FIG.

The insulating protective layer 112 can be formed by apply | coating the composition for insulating protective layers on the surface of the transfer film 115. FIG. The composition for an insulating protective layer may be prepared by adding an appropriate amount of solvent to the resin for the insulating protective layer, for example.

Although the thickness of the insulating protective layer 112 is not specifically limited, Although it can set suitably as needed, Preferably it is 1 micrometer or more, More preferably, it is 4 micrometers or more, Preferably it is 20 micrometers or less, More preferably, 10 micrometers or less, More preferably, it can be 5 micrometers 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 making the thickness of the insulating protective layer 112 into 20 micrometers or less, it becomes easy to make the elasticity modulus and breaking elongation of the electromagnetic wave shielding film 101 into a predetermined value.

When providing the shielding layer 113, the shielding layer 113 can be formed by metal foil, a vapor deposition film, a conductive filler, etc.

The metal foil is not particularly limited, but may be a foil composed of any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, or an alloy containing two or more thereof. have.

Although the thickness of a metal foil is not specifically limited, 0.5 micrometer or more is preferable and 1.0 micrometer or more is more preferable. When the thickness of metal foil is 0.5 micrometer or more, when the high frequency signal of 10 MHz-100 GHz is transmitted to a shielded printed wiring board, the attenuation amount of a high frequency signal can be suppressed. Moreover, 12 micrometers or less are preferable, as for the thickness of a metal foil, 10 micrometers or less are more preferable, and its 7 micrometers or less are more preferable. If the thickness of a metal layer is 12 micrometers or less, raw material cost can be suppressed and break elongation of a shielding film will become favorable.

Although a vapor deposition film is not specifically limited, Nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, etc. can be formed by vapor-depositing. For vapor deposition, electrolytic plating, electroless plating, sputtering, electron beam deposition, vacuum deposition, chemical vapor deposition (CVD), metal organic deposition (MOCVD), or the like can be used.

Although the thickness of a vapor deposition film is not specifically limited, 0.05 micrometer or more is preferable and 0.1 micrometer or more is more preferable. If the thickness of a metal vapor deposition film is 0.05 micrometer or more, the electromagnetic wave shielding film will be excellent in the characteristic which an electromagnetic wave shields in an shielding printed wiring board. In addition, the thickness of the metal deposited film is preferably less than 0.5 µm, more preferably less than 0.3 µm. If the thickness of the metal vapor deposition film is less than 0.5 micrometer, it is excellent in the bending resistance of an electromagnetic wave shielding film, and it can suppress that a shielding layer is destroyed by the step provided in the printed wiring board.

In the case of a conductive filler, the shielding layer 113 can be formed by apply | coating the solvent which mix | blended the conductive filler to the surface of the insulating protective layer 112, and drying it. As the conductive filler, a metal filler, a metal coating resin filler, a carbon filler, and a mixture thereof can be used. As the metal filler, copper powder, silver powder, nickel powder, silver coated copper powder, gold coated copper powder, silver coated nickel powder, gold coated nickel powder and the like can be used. These metal powders can be produced by an electrolytic method, an atomizing method, or a reducing method. Examples of the shape of the metal powder include spherical, flake, fibrous, and resinous forms.

In the present embodiment, the thickness of the shielding layer 113 is preferably appropriately selected according to the required electromagnetic shielding effect and repeated bending and sliding resistance. However, in the case of metal foil, the viewpoint of securing the elongation at break is ensured. It is preferable to set it as 12 micrometers or less.

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

When the conductive adhesive layer 111 contains a thermoplastic resin, examples of the thermoplastic resin include styrene resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, imide resin, and the like. Acrylic resin etc. can be used. These resin may be used individually by 1 type, and may use 2 or more types together.

When the conductive adhesive layer 111 contains a thermosetting resin, for example, a phenol resin, an epoxy resin, a urethane resin, a melamine resin, a polyamide resin, an alkyd resin, or the like can be used as the thermosetting resin. . Although it does not specifically limit as an active energy ray curable composition, For example, the polymeric compound etc. which have at least two (meth) acryloyloxy group in a molecule | numerator can be used. These compositions may be used individually by 1 type, and may use 2 or more types together.

Thermosetting resin contains the 1st resin component which has a reactive 1st functional group, for example, and the 2nd resin component which reacts with a 1st functional group. A 1st functional group can be made into an epoxy group, an amide group, a hydroxyl group, etc., for example. What is necessary is just to select a 2nd functional group according to a 1st functional group, For example, when a 1st functional group is an epoxy group, it can be set as a hydroxyl group, a carboxyl group, an epoxy group, an amino group, etc. Specifically, for example, when the first resin component is an epoxy resin, the epoxy resin-modified polyester resin, the epoxy-group-modified polyamide resin, the epoxy-group-modified acrylic resin, the epoxy-group-modified polyurethane polyurea resin, as the second resin component, A carboxyl group-modified polyester resin, a carboxyl group-modified polyamide resin, a carboxyl group-modified acrylic resin, a carboxyl group-modified polyurethanepolyurea resin, a urethane-modified polyester resin, etc. can be used. Among these, carboxyl group-modified polyester resin, carboxyl group-modified polyamide resin, carboxyl group-modified polyurethanepolyurea resin, and urethane-modified polyester resin are preferable. In addition, when a 1st resin component is a hydroxyl group, as a 2nd resin component, an epoxy-group-modified polyester resin, an epoxy-group-modified polyamide resin, an epoxy-group-modified acrylic resin, an epoxy-group-modified polyurethane polyurea resin, a carboxyl group-modified polyester resin, and carboxyl group-modified Polyamide resin, carboxyl group-modified acrylic resin, carboxyl group-modified polyurethanepolyurea resin, urethane-modified polyester resin, etc. can be used. Among these, carboxyl group-modified polyester resin, carboxyl group-modified polyamide resin, carboxyl group-modified polyurethanepolyurea resin, and urethane-modified polyester resin are preferable.

Thermosetting resin may also contain the hardening | curing agent which accelerates | stimulates a thermosetting reaction. When a thermosetting resin has a 1st functional group and a 2nd functional group, a hardening | curing agent can be suitably selected according to the kind of 1st functional group and 2nd functional group. When a 1st functional group is an epoxy group and a 2nd functional group is a hydroxyl group, an imidazole series hardening | curing agent, a phenolic hardening | curing agent, a cationic hardening | curing agent, etc. can be used. These may be used individually by 1 type and may use 2 or more types together. In addition, as an optional component, an antifoamer, antioxidant, a viscosity modifier, a diluent, a sedimentation inhibitor, a leveling agent, a coupling agent, a coloring agent, a flame retardant, etc. may be included.

Although an electroconductive filler is not specifically limited, For example, a metal filler, a metal coating resin filler, a carbon filler, and a mixture thereof can be used. Examples of the metal filler include copper powder, silver powder, nickel powder, silver coated copper powder, gold coated copper powder, silver coated nickel powder, gold coated nickel powder and the like. These metal powders can be produced by electrolytic method, atomization method, reduction method or the like. Among these, any of silver powder, silver coated copper powder, and copper powder is preferable.

In terms of contact between the fillers, the conductive fillers preferably have an average particle diameter of 1 µm or more, more preferably 3 µm or more, 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, flake, dendritic, fibrous or the like.

Although content of an electroconductive filler can be selected suitably according to a use, Preferably it is 5 mass% or more, More preferably, it is 10 mass% or more, Preferably it is 95 mass% or less, More preferably, 90 mass% in all solid content. It is as follows. From a viewpoint of embedding property, Preferably it is 70 mass% or less, More preferably, it is 60 mass% or less. In addition, when implementing anisotropic conductivity, Preferably it is 40 mass% or less, More preferably, it is 35 mass% or less.

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

It is preferable that the thickness of the electroconductive adhesive bond layer 111 shall be 1 micrometer-50 micrometers from a viewpoint of controlling embedding.

And if necessary, the protective film which can be peeled off may be bonded to the surface of the conductive adhesive layer 111.

The electromagnetic wave shielding film 101 of this embodiment can be set as the shielding wiring board 103 in combination with the printed wiring board 102 as shown in FIG. The electromagnetic wave shielding film 101 may have the shielding layer 113.

The printed wiring board 102 has, for example, a printed circuit including a base member 122 and a ground circuit 125 provided on the base member 122. The insulator film 121 is adhered on the base member 122 by the adhesive layer 123. The insulator film 121 is provided with an opening that exposes the ground circuit 125. A surface layer such as a plating layer may be formed on the exposed portion of the ground circuit 125. The printed wiring board 102 may be a flexible substrate or a rigid substrate.

When attaching the electromagnetic wave shielding film 101 to the printed wiring board 102, the electromagnetic wave shielding film 101 is disposed on the printed wiring board 102 so that the conductive adhesive layer 111 is positioned over the opening. And the electromagnetic wave shielding film 101 and the printed wiring board 102 are clamped from a vertical direction by predetermined | prescribed pressure by two heating plates (not shown) heated at predetermined temperature (for example, 120 degreeC). (For example, 0.5 MPa) is pressed for a 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 two heating plates is made into predetermined temperature (for example, 170 degreeC) which is higher temperature than the said temporarily fixed time, and it is predetermined time (for example, 30) by predetermined pressure (for example, 3 MPa). Min) Pressurized. Thereby, the electromagnetic wave shielding film 101 can be fixed to the printed wiring board 102. When pressurizing, the electroconductive adhesive layer 111 is fully embedded in an opening part, and the intensity | strength and electroconductivity which the electromagnetic wave shielding film 101 requires are realizable.

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

EXAMPLE

EMBODIMENT OF THE INVENTION Below, the electromagnetic wave shielding film of this indication is demonstrated in detail using an Example. The following examples are illustrative and are not intended to limit the invention.

<Production of electromagnetic shielding film>

The release agent was apply | coated to the surface of the predetermined | prescribed transfer film. On the surface of the transfer film which apply | coated the mold release agent, the composition for insulating protective layers was apply | coated using a wire bar, and it heat-dried, and the insulating protective layer was formed. Next, after apply | coating the composition for conductive adhesive layers with a wire bar on the insulating protective layer, 100 degreeC x 3 minutes were dried and the electromagnetic wave shielding film was produced.

The composition for insulating protective layers was made into the 2-layered structure of the hard-coat layer of polyester-type transparent resin whose thickness is 2 micrometers, and the soft coating layer of the carbon black containing epoxy-type black resin whose thickness is 3 micrometers. The composition for electrically conductive adhesive layers was made to add the dendritic silver coating copper powder of 5 micrometers of average particle diameters as electroconductive fine particles to phosphorus flame retardant containing epoxy resin. The thickness of the conductive adhesive layer was 15 µm.

<Measurement of surface properties>

The parameters for the surface properties were measured in accordance with ISO25178 using a laser microscope (VK-X210, manufactured by Keyence Co., Ltd., lens magnification 50 times). The measurement was performed with respect to the surface which forms the insulating protective layer of the unused transfer film cut out in 5.0 cm x 5.0 cm. The arbitrary ten places in surface were measured, and the arithmetic mean value was used as a measured value. In addition, the standard deviation SD and the coefficient of variation CV were calculated.

<Measurement of peeling strength>

The electromagnetic wave shielding film was pressed on the conditions of temperature: 170 degreeC, time: 30 minutes, and pressure: 2-3 MPa using the press. After the electromagnetic wave shielding film returned to normal temperature, the peeling strength of the transfer film was measured for the peeling film on the surface using the peeling strength tester (Palmek Co., Ltd. product, PFT50S). The measurement was performed at normal temperature on 1000 mm / min of tensile velocity, and 170 degree of peel angles. The measurement was performed 10 times and the minimum value, the maximum value, and the average value were calculated | required.

(Example 1)

A PET film having a thickness of 50 µm was used as the transfer film. The surface of the insulating protective layer after peeling off the transfer film became a matte surface. Sv in the insulating protective layer formation surface of the transfer film was 3.1 micrometers, Sz was 8.0 micrometers, and Sa was 0.69 micrometer. The variation coefficient of Sv was 0.15, and the variation coefficient of Sz was 0.02. The minimum value of 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)

A PET film having a thickness of 50 µm was used as the transfer film. The surface of the insulating protective layer after peeling off the transfer film became a matte surface. Sv in the insulating protective layer formation surface of the transfer film was 2.5 micrometers, Sz was 6.6 micrometers, and Sa was 0.41 micrometer. The variation coefficient of Sv was 0.12 and the variation coefficient of Sz was 0.08. The minimum value of 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)

A PET film having a thickness of 50 µm was used as the transfer film. The surface of the insulating protective layer after peeling off the transfer film became a matte surface. Sv in the insulating protective layer formation surface of the transfer film was 5.9 micrometers, Sz was 9.6 micrometers, and Sa was 0.69 micrometer. The variation coefficient of Sv was 0.07, and the variation coefficient of Sz was 0.09. The minimum value of peeling 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)

A PET film having a thickness of 50 µm was used as the transfer film. The surface of the insulating protective layer after peeling off the transfer film became a matte surface. Sv in the insulating protective layer formation surface of the transfer film was 6.8 micrometers, Sz was 11.4 micrometers, and Sa was 0.48 micrometer. The variation coefficient of Sv was 0.43 and the variation coefficient of Sz was 0.40. The minimum value of peeling strength was 7.0 N / 50 mm, and the maximum value could not be measured exceeding 10 N / 50 mm.

(Comparative Example 2)

A PET film having a thickness of 50 µm was used as the transfer film. The surface of the insulating protective layer after peeling off the transfer film became a glossy surface. Sv in the insulating protective layer formation surface of the transfer film was 0.8 µm, Sz was 1.3 µm, and Sa was 0.06 µm. The variation coefficient of Sv was 0.23 and the variation coefficient of Sz was 0.13. The minimum value of 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 each Example and Comparative Example. In addition to Sv and Sz, the data also include kurtosis (Sku), minimum autocorrelation length (Sal), surface aspect ratio (Str), protruding valley height (Svk), and loading area ratio (Smr2) separating the protruding valley and the core. It is described.

TABLE 1

The electromagnetic wave shielding film of this indication is easy to peel a transfer film, and can improve productivity.

101: electromagnetic shielding film
102: printed wiring board
103: shielded wiring board
111: conductive adhesive layer
112: insulation protective layer
113: shielding layer
115: transfer film
121: insulator film
122: base member
123: adhesive layer
125: ground circuit

Claims (2)

Insulation protective layer,
A transfer film provided on a surface of the insulating protective layer;
A conductive adhesive layer provided on the side opposite to said transfer film of said insulating protective layer,
The electromagnetic wave shielding film of the surface of the said insulating protective layer side of the said transfer film whose maximum valley depth Sv is 1 micrometer or more and 6 micrometers or less, and maximum height Sz is 2 micrometers or more and 10 micrometers or less. The method of claim 1,
The electromagnetic wave shielding film in which the variation coefficient of the maximum bone depth Sv and the variation coefficient of the maximum height Sz in the surface of the said transfer protective film side of the said insulating film are 0.2 or less.

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