TWI743368B - Electromagnetic wave shielding film and shielding printed wiring board - Google Patents

Abstract

The subject of the present invention is to realize an electromagnetic wave shielding film with optimized overall physical properties.

The electromagnetic wave shielding film of the solution of the present invention has a conductive adhesive layer and an insulating protective layer. The tensile elastic modulus of the electromagnetic wave shielding film is more than 400MPa, and the breaking elongation is more than 3%.

Description

Electromagnetic wave shielding film and shielding printed wiring board

Field of invention

This disclosure relates to an electromagnetic wave shielding film.

Background of the invention

By crimping the electromagnetic wave shielding film on the surface of the printed wiring board, the conductive adhesive layer is embedded in the opening of the insulating film covering the surface of the printed wiring board, so that the conductive adhesive layer and the printed wiring The ground pattern of the substrate is conductive. In recent years, with the development of the miniaturization of electronic equipment, the size of the opening for embedding the conductive adhesive layer has also been gradually reduced. Therefore, the conductive adhesive layer is required to have excellent embedding properties. In addition, it is also required that the conductive adhesive layer should not be cracked due to the height difference provided on the printed wiring board. Therefore, it has been reviewed to control the fluidity of the conductive adhesive layer to make the embedding property good (for example, refer to Patent Document 1).

Prior art literature Patent literature

Patent Document 1: International Publication No. 2014/010524

Summary of the invention

However, although physical properties other than liquidity will also affect embeddedness and edge cracking, physical properties other than liquidity have hardly been considered. In addition, the electromagnetic wave shielding film is formed by laminating not only a conductive adhesive layer but also a plurality of layers including an insulating protective layer. Therefore, in order to improve embedding and suppress edge cracks, it is necessary to optimize the physical properties of the entire electromagnetic wave shielding film.

The subject of the present disclosure is to realize an electromagnetic wave shielding film with optimized overall physical properties.

One aspect of the electromagnetic wave shielding film of the present disclosure has a conductive adhesive layer and an insulating protective layer, and the electromagnetic wave shielding film has a tensile elastic modulus of 400 MPa or more, and a breaking elongation of 3% or more.

In one aspect of the electromagnetic wave shielding film, there may be a metal foil provided between the conductive adhesive layer and the insulating protective layer.

In one aspect of the electromagnetic wave shielding film, it can be provided that there is a metal vapor-deposited layer between the conductive adhesive layer and the insulating protective layer, and the breaking elongation of the electromagnetic wave shielding film is more than 10%.

In one aspect of the electromagnetic wave shielding film, the conductive adhesive layer may be in contact with the insulating protective layer, and the breaking elongation of the electromagnetic wave shielding film is 10% or more.

One aspect of the shielded printed wiring board of the present disclosure includes: a printed wiring board having a grounding circuit and an insulating film, the insulating film having an opening that exposes the grounding circuit; and the electromagnetic wave shielding film of the present disclosure; and, a conductive adhesive The agent layer and the insulating film are connected to the opening to conduct a ground circuit.

According to the electromagnetic wave shielding film of the present disclosure, the embedding property can be improved.

101: Electromagnetic wave shielding film

102: Printed wiring board

103: Shielded printed wiring board

111: Conductive adhesive layer

112: insulating protective layer

113: shielding layer

121: insulating film

122: base member

123: Adhesive layer

125: Ground circuit

128: Opening

140: Printed wiring board for test

141: Copper foil pattern

142: Insulation layer

143: Opening

151: Resistance meter

Fig. 1 is a cross-sectional view showing an electromagnetic wave shielding film according to an embodiment.

Fig. 2 is a cross-sectional view showing a modification of the electromagnetic wave shielding film.

Fig. 3 is a cross-sectional view showing a shielded printed wiring board according to an embodiment.

4 is a cross-sectional view showing the step of attaching the electromagnetic wave shielding film to the printed wiring board.

Figure 5 is a top view showing the method of evaluating embedding.

The form used to implement the invention

The electromagnetic wave shielding film 101 of this embodiment has an insulating protective layer 112 and a conductive adhesive layer 111 as shown in FIG. 1. Such an electromagnetic wave shielding film can make the conductive adhesive layer 111 function as a shield. In addition, as shown in FIG. 2, a shielding layer 113 may be provided between the insulating protection layer 112 and the conductive adhesive layer 111. The shielding layer 113 only needs to be conductive, and it may be a layer of a metal foil, a metal vapor-deposited film, a conductive filler, or the like.

The electromagnetic wave shielding film 101 of this embodiment can be combined with a printed wiring board 102 as shown in FIG. 3 to make a shielding printed wiring board 103. In addition, the electromagnetic wave shielding film 101 may have a shielding layer 113.

The printed wiring board 102, for example, has: a base Member 122; and a printed circuit including a ground circuit 125 provided on the base member 122. An insulating film 121 is adhered on the base member 122 via the adhesive layer 123. In addition, the insulating film 121 is provided with an opening that exposes the ground circuit 125. The exposed part of the ground circuit 125 may be provided with a surface layer such as a gold plating layer. In addition, the printed wiring substrate 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, as shown in FIG. Then, using two heating plates (not shown) heated to a predetermined temperature (for example, 120°C), sandwich the electromagnetic wave shielding film 101 and the printed wiring board 102 from above and below and apply a predetermined pressure (for example, 0.5 MPa) Press 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, set the temperature of the two heating plates to a predetermined temperature (for example, 170° C.) higher than the aforementioned temporary fixation, and pressurize with a predetermined pressure (for example, 3 MPa) for a predetermined time (for example, 30 minutes). Thereby, the electromagnetic wave shielding film 101 can be fixed to the printed wiring board 102. When the pressure is applied, the conductive adhesive layer 111 is fully embedded in the opening 128, so that the required strength and conductivity of the electromagnetic wave shielding film 101 can be achieved.

Even if the fluidity of the conductive adhesive layer 111 is increased, the conductive adhesive layer 111 will not flow into the opening 128 when it is pressurized, but will be pushed out and diffused around. Therefore, in order to improve the embedding property, it is important that the conductive adhesive layer 111 is deformed and pressed into the opening 128. Therefore, it is advisable to prevent the stress applied to the conductive adhesive layer 111 from dissipating To the surroundings. Therefore, it is preferable to increase the elastic modulus of the entire electromagnetic wave shielding film 101 to apply a large stress to the conductive adhesive layer 111. Specifically, the elastic modulus of the entire electromagnetic wave shielding film 101 is 400 MPa or more, preferably 500 MPa or more, and more preferably 600 MPa or more.

On the other hand, when the conductive adhesive layer 111 is pressed into the opening 128, not only the conductive adhesive layer 111 but the entire electromagnetic wave shielding film 101 including the insulating protective layer 112 and the like will be deformed. Therefore, the elongation at break is set to 3% or more, preferably 4% or more, and more preferably 5% or more, so that the electromagnetic wave shielding film 101 as a whole has a certain degree of flexibility. In addition, the modulus of elasticity is preferably set to 15000 MPa or less, more preferably set to 14900 MPa or less, and more preferably set to 14800 MPa or less.

The elongation at break of the electromagnetic wave shielding film 101 will vary greatly depending on the presence or absence of the shielding layer 113 and its material. When the shielding layer 113 made of metal foil is provided, it is difficult to increase the elongation at break, and it is usually about 10% or less. When the shielding layer 113 composed of a metal vapor-deposited layer is provided, a larger breaking elongation can be ensured, preferably a breaking elongation of 10% or more can be ensured, preferably 20% or more, and more preferably 30% or more. Even when the shielding layer 113 is not provided, it is better to ensure a breaking elongation of 10% or more, preferably 20% or more, and more preferably 30% or more. In addition, when the shielding layer 113 is not provided, the elastic modulus is preferably set to 2000 MPa or less, and preferably can be set to 1000 MPa or less. In addition, the modulus of elasticity and the elongation at break can be measured by the methods described in the examples.

By setting the modulus of elasticity and the elongation at break of the electromagnetic wave shielding film 101 to the above-mentioned values, not only the embedding property is taken into consideration, but also the height difference can be suppressed. Edge cracks occurred.

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, as the thermoplastic resin, for example, styrene resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, imine resin, and acrylic resin can be used. Department of resin and so on. These resins 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, as the thermosetting resin, for example, phenol resin, epoxy resin, urethane resin, melamine resin, polyamide resin, and alkyd resin can be used. Resin etc. Although there are no particular limitations on the active energy ray curable composition, for example, a polymerizable compound having at least two (meth)acryloyloxy groups in the molecule can be used. These compositions may be used individually by 1 type, and may use 2 or more types together.

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, an amino group, or a hydroxyl group. The second functional group only needs to be selected based on 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 amino group, or the like. Specifically, for example, when the first resin component is epoxy resin, the second resin component can be used: epoxy modified polyester resin, epoxy modified polyamide resin, epoxy modified acrylic resin, Epoxy modified polyurethane polyurea resin, carboxy modified polyester resin, carboxy modified polyamide Amine resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin, urethane modified polyester resin, etc. Among them, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin and urethane modified polyester resin are preferred. In addition, when the first resin component is a hydroxyl group, the second resin component can be used: epoxy-modified polyester resin, epoxy-modified polyamide resin, epoxy-modified acrylic resin, epoxy-modified poly Urethane polyurea resin, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin and urethane modified polyester resin Wait. Among them, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin, and urethane modified polyester resin are preferred.

The thermosetting resin may also contain a curing agent that promotes the thermosetting reaction. When the thermosetting resin has a first functional group and a second functional group, the curing agent can be appropriately selected according to 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 curing agent, a phenol-based curing agent, a cationic curing agent, and the like can be used. These may be used individually by 1 type, and may use 2 or more types together. In addition, defoamers, antioxidants, viscosity regulators, diluents, anti-settling agents, leveling agents, coupling agents, colorants and flame retardants can also be included as optional ingredients.

Although the conductive filler is not particularly limited, for example, metal fillers, coated metal resin fillers, carbon fillers, and mixtures 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, and gold-coated nickel powder. These metal powders can It is produced by electrolysis, atomization, reduction, etc. Among them, any one of silver powder, silver-clad copper powder and copper powder is preferred.

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

The content of the conductive filler can be appropriately selected according to the application, but the total solid content is preferably 5 mass% or more, more preferably 10 mass% or more, preferably 95 mass% or less, and preferably 90 mass% or less. From the viewpoint of embedding properties, it is preferably 70% by mass or less, and more preferably 60% by mass or less. In addition, when realizing anisotropic conductivity, it is preferably 40% by mass or less, and more preferably 35% by mass or less.

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

The thermoplastic resin is not particularly limited, and styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imine resins, acrylic resins, and the like can be used. The thermosetting resin is not particularly limited, and a phenol resin, epoxy resin, urethane resin, melamine resin, alkyd resin, or the like can be used. The active energy ray-curable resin is not particularly limited, but for example, a polymerizable compound having at least two (meth)acryloxy groups in the molecule can be used. Although the protective layer is formed of a single material, it can also be made of two or more The above material is formed.

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 it is made into a laminate of a low-hardness outer layer and a high-hardness inner layer, because the outer layer has a buffering effect, it can ease the application of the electromagnetic wave shielding film 101 to the shielding layer during the step of heating and pressing on the printed wiring board 102 The pressure of 113. Therefore, the shielding layer 113 can be prevented from being damaged due to the height difference provided on the printed wiring board 102.

The insulating protective layer 112 may optionally contain at least one of the following components: hardening accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, ultraviolet absorbers, defoamers, leveling agents, Fillers, flame retardants, viscosity regulators and anti-caking agents, etc.

The thickness of the insulating protective layer 112 is not particularly limited, and can be appropriately set as needed, and is preferably 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 be 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, it becomes easy to set the elastic modulus and the elongation at break of the electromagnetic wave shielding film 101 to predetermined values.

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

Although the metal foil is not particularly limited, it may be any one of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, etc., or a foil composed of an alloy containing two or more of them.

Although the thickness of the metal foil is not particularly limited, it is preferably 0.5 μm or more, preferably 1.0 μm or more. If the thickness of the metal foil is 0.5μm or more, it can suppress the attenuation of the high-frequency signal when transmitting high-frequency signals from 10MHz to 100GHz to the shielded printed wiring board.

In addition, the thickness of the metal foil is preferably 12 μm or less, preferably 10 μm or less, and more preferably 7 μm or less. If the thickness of the metal layer is 12 μm or less, the cost of raw materials can be suppressed, and at the same time, the elongation at break of the shielding film will be improved.

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

Although the thickness of the metal vapor-deposited film is not particularly limited, it is preferably 0.05 μm or more, and more preferably 0.1 μm or more. If the thickness of the metal vapor-deposited film is 0.05 μm or more, the electromagnetic wave shielding film has excellent electromagnetic wave shielding characteristics in shielding printed wiring boards.

In addition, the thickness of the metal vapor-deposited film is preferably less than 0.5 μm, and more preferably less than 0.3 μm. If the thickness of the metal vapor-deposited film is less than 0.5 μm, the electromagnetic wave shielding film has excellent flex resistance, and the shielding layer can be prevented from being damaged due to the height difference provided on the printed wiring board.

If it is a conductive filler, the shielding layer 113 can be formed by coating the surface of the insulating protective layer 112 with a solvent mixed with the conductive filler and drying it. As the conductive filler, metal fillers, coated metal resin fillers, carbon fillers, and mixtures of these can be used. Can be used as 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, etc. These metal powders can be produced by electrolysis, atomization and reduction methods. The shape of the metal powder can be spherical, flake, fibrous, dendritic, etc.

In this embodiment, the thickness of the shielding layer 113 may be appropriately selected in accordance with the electromagnetic shielding effect and the resistance to repeated deflection/slippage. However, when it is a metal foil, it is preferably set to 12μm from the viewpoint of ensuring the elongation at break. the following.

The electromagnetic wave shielding film 101 of this embodiment can be formed in the following manner, for example. First, the insulating protective layer composition is coated on the supporting substrate, and then heated and dried and the solvent is removed to form the insulating protective layer 112. The supporting substrate can be made into a film shape, for example. The support base material is not particularly limited, and it can be formed using materials such as polyolefin-based, polyester-based, polyimide-based, or polyphenylene sulfide-based materials, for example. A release agent layer may also be provided between the support base material and the protective layer composition.

The composition for the insulating protective layer can be prepared by adding a suitable amount of solvent and other admixtures to the resin composition for the insulating protective layer. The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. As other admixtures, crosslinking agents, polymerization catalysts, hardening accelerators and coloring agents can be added. Other admixtures can be added as long as they are required, or not added. The method of coating the protective layer composition on the supporting substrate is not particularly limited, and well-known techniques such as lip coating, comma coating, gravure coating, or slit die coating can be used.

Secondly, a shielding layer 113 is formed on the insulating protection layer 112 as required. The method of forming the shielding layer 113 can be appropriately selected according to the type of the shielding layer 113. When the electromagnetic wave shielding film 101 has a structure without the shielding layer 113, this step can be omitted.

Next, after coating the conductive adhesive layer composition on the insulating protective layer 112 or the shielding layer 113, it is heated and dried and the solvent is removed to form the conductive adhesive layer 111.

The conductive adhesive layer composition contains a conductive adhesive and a solvent. The solvent can be, for example, toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The ratio of the conductive adhesive in the composition for the conductive adhesive layer only needs to be appropriately set according to the thickness of the conductive adhesive layer 111 and the like.

The method of coating the conductive adhesive layer composition on the shielding layer 113 is not particularly limited, and lip coating, chamfer coating, gravure coating, or slit die coating can be used.

The thickness of the conductive adhesive layer 111 is preferably 1 μm to 50 μm from the viewpoint of controlling the elastic modulus and breaking elongation of the electromagnetic wave shielding film 101.

In addition, if necessary, a release substrate (separation film) may be attached to the surface of the conductive adhesive layer 111. The peeling substrate can use the following: on the base film of polyethylene terephthalate, polyethylene naphthalate, etc., a silicon-based or non-silicon-based release agent is coated to form conductivity It is formed by adhering the surface on the side of the agent layer 111. In addition, the thickness of the peeling substrate is not particularly limited, and it can be determined in consideration of the ease of use.

Example

Hereinafter, examples of the use of the electromagnetic wave shielding film of the present disclosure will be described in more detail. The following examples are examples, and are not intended to limit the present invention.

<Production of electromagnetic wave shielding film>

On the surface of the PET film (thickness 25μm) that is a supporting substrate and has a release layer provided on the surface, a predetermined resin composition for an insulating protective layer is coated with a wire rod and heated and dried to form an insulating protective layer with a predetermined thickness. Afterwards, when there is a shielding layer, a shielding layer is formed on the insulating protective layer by a predetermined method. Next, after coating the predetermined conductive adhesive layer composition on the insulating protective layer or the shielding layer by a wire rod, it is dried at 100° C.×3 minutes to prepare an electromagnetic wave shielding film.

<Determination of physical properties>

A dumbbell test piece (100 mm×10 mm, 20 mm between the marking lines) was prepared from the obtained electromagnetic wave shielding film, and the elastic modulus, elongation at break, and maximum stress were measured using a tensile testing machine (AGS-X50S, manufactured by Shimadzu Corporation). The measurement conditions are as follows: tensile speed: 50mm/min, load cell: 50N, and elastic modulus is calculated from the gradient of stress (2~3MPa) and elongation at break.

<Evaluation of Embeddedness>

As shown in Figure 5, under the conditions of temperature: 170°C, time: 30 minutes, and pressure: 2 to 3 MPa, the electromagnetic wave shielding film 101 is adhered to the test printed wiring board 140 using a press to obtain a shielding printed wiring board . The test printed wiring board 140 has: two copper foil patterns 141, which are provided on a base film (not shown) and extend parallel to each other at intervals; and an insulating layer (Thickness: 25 μm) 142 is covered with a copper foil pattern and is made of polyimide; and the insulating layer 142 is provided with an opening 143 that simulates a grounding portion with a diameter of 1 mm.

The resistance value between the two copper foil patterns 141 formed on the test printed wiring board 140 was measured by the resistance meter 151, and the connection resistance value between the copper foil pattern 141 and the electromagnetic wave shielding film 101 was measured, and the resin embedding in the opening 143 was evaluated sex. The case where the connection resistance value per opening part is less than 300mΩ is evaluated as good insertability (○), and the case where the connection resistance value is more than 300mΩ is evaluated as poor insertability (×).

(Example 1)

Let the resin composition for the insulation protection layer be the first insulation protection layer resin composition composed of UV curable acrylic resin and the second insulation protection layer resin composition composed of rubber-modified epoxy resin, and the PET film After forming a first insulating protective layer with a thickness of 2 μm on the surface of the, a second insulating protective layer with a thickness of 3 μm is formed on the first insulating protective layer.

The shielding layer is a silver vapor-deposited film with a thickness of 0.15 μm, which is formed on the surface of the second insulating protective layer by vacuum vapor deposition. The conductive adhesive layer is set such that the resin component is rubber-modified epoxy resin (87 parts by mass), the filler is silver-coated copper powder (13 parts by mass), and the thickness is 17 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 1311 MPa, the elongation at break is 45%, the maximum stress is 19 MPa, and the embedding property is good.

(Example 2)

The electromagnetic wave shielding film was prepared in the same manner as in Example 1, except that the first insulating protective layer was an epoxy-modified polyester resin with a thickness of 2 μm and the shielding layer was a silver vapor-deposited film with a thickness of 0.3 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 1442 MPa, the elongation at break is 47%, the maximum stress is 18 MPa, and the embedding property is good.

(Example 3)

The electromagnetic wave shielding film was produced in the same manner as in Example 2 except that the thickness of the conductive adhesive layer was 5 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 1235 MPa, the elongation at break is 94%, the maximum stress is 18 MPa, and the embedding property is good.

(Example 4)

An electromagnetic wave shielding film was produced in the same manner as in Example 1, except that the first insulating protective layer was made of epoxy modified polyester resin with a thickness of 2 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 825MPa, the elongation at break is 69%, the maximum stress is 16MPa, and the embedding property is good.

(Example 5)

The electromagnetic wave shielding film was produced in the same manner as in Example 4 except that the thickness of the conductive adhesive layer was 5 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 715 MPa, the elongation at break is 83%, the maximum stress is 15 MPa, and the embedding property is good.

(Example 6)

Except that the thickness of the second insulating protective layer is 5μm, the resin component of the conductive adhesive layer is rubber-modified epoxy resin (40 parts by mass), the filler is silver-coated copper powder (60 parts by mass), and there is no shield Except for the layers, the electromagnetic wave shielding film was produced in the same manner as in Example 2.

The elastic modulus of the obtained electromagnetic wave shielding film is 404MPa, the elongation at break is 119%, the maximum stress is 25MPa, and the embedding property is good.

(Example 7)

Except that the thickness of the second insulating protective layer is 3μm, and the resin component of the conductive adhesive layer is a mixture of rubber-modified epoxy resin and polyester resin (99:1 by weight), the rest is An electromagnetic wave shielding film was produced in the same manner as in Example 6.

The elastic modulus of the obtained electromagnetic wave shielding film is 685MPa, the elongation at break is 71%, the maximum stress is 55MPa, and the embedding property is good.

(Example 8)

Except that the first insulating protective layer is made of phenol-modified epoxy resin with a thickness of 2μm, the second insulating protective layer is made of rubber-modified epoxy resin with a thickness of 5μm, and the shielding layer is a rolled copper foil with a thickness of 5μm. , And the rest was prepared in the same manner as in Example 1 to produce an electromagnetic wave shielding film.

The obtained electromagnetic wave shielding film has an elastic modulus of 14709 MPa, a breaking elongation of 4%, a maximum stress of 53 MPa, and good embedding properties.

(Example 9)

The electromagnetic wave shielding film was produced in the same manner as in Example 8 except that the thickness of the rolled copper foil was 2 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 5916 MPa, the elongation at break is 6%, the maximum stress is 28 MPa, and the embedding property is good.

(Comparative example 1)

The first insulating protective layer is made of urethane modified epoxy resin with a thickness of 7 μm, and the second insulating protective layer and shielding layer are not provided. For the conductive adhesive layer, the resin component is urethane modified epoxy resin (87 parts by mass), the filler is silver-coated copper powder (13 parts by mass), and the thickness is 17 μm.

The elastic modulus of the obtained electromagnetic wave shielding film is 389MPa, the elongation at break is 164%, the maximum stress is 17MPa, and the embedding property is not good.

(Comparative example 2)

Except that the thickness of the first insulating protective layer was 5 μm, the shielding layer was a rolled copper foil with a thickness of 2 μm, and the thickness of the conductive adhesive layer was 12 μm, the electromagnetic wave shielding film was produced in the same manner as in Comparative Example 1.

The elastic modulus of the obtained electromagnetic wave shielding film is 15394MPa, the elongation at break is 2%, the maximum stress is 100MPa, and the embedding property is not good.

The examples and comparative examples are summarized and shown in Table 1.

Industrial availability

The electromagnetic wave shielding film of the present disclosure has excellent embedding properties and is therefore useful as an electromagnetic wave shielding film for printed wiring boards.

101: Electromagnetic wave shielding film

111: Conductive adhesive layer

112: insulating protective layer

Claims (5)

An electromagnetic wave shielding film, which has a conductive adhesive layer, an insulating protective layer, and a metal foil arranged between the conductive adhesive layer and the insulating protective layer; the electromagnetic wave shielding film has a tensile elastic modulus of 600 MPa or more, breaking Elongation is 3% or more; and the aforementioned insulating protective layer is made of thermoplastic resin, phenol resin, epoxy resin, urethane resin, melamine resin or alkyd resin, or active energy ray curable resin . An electromagnetic wave shielding film having a conductive adhesive layer, an insulating protective layer, and a metal vapor-deposited layer on the side surface of the conductive adhesive layer of the insulating protective layer; the tensile elastic modulus of the electromagnetic wave shielding film is 600 MPa or more, The elongation at break is 10% or more; and the aforementioned insulating protective layer is made of thermoplastic resin, phenol resin, epoxy resin, urethane resin, melamine resin or alkyd resin, or active energy ray curable Resin. An electromagnetic wave shielding film, which has a conductive adhesive layer and an insulating protective layer, and the conductive adhesive layer is in contact with the insulating protective layer; the electromagnetic wave shielding film has a tensile elastic modulus of 600 MPa or more, and a breaking elongation of 10 % Or more; and the aforementioned insulating protective layer is made of thermoplastic resin, phenol resin, epoxy resin, urethane resin, melamine resin or alkyd System resin, or active energy ray curable resin. An electromagnetic wave shielding film according to any one of claims 1 to 3, wherein the insulating protective layer includes a first layer and a second layer, and the second layer has a higher hardness than the first layer and is provided on the conductive adhesive layer side. A shielded printed wiring board comprising: a printed wiring board having a ground circuit and an insulating film, the insulating film having an opening that exposes the aforementioned ground circuit; and the electromagnetic wave shielding film according to any one of claims 1 to 4; and, The conductive adhesive layer is connected to the insulating film to conduct the ground circuit at the opening.

Images