CN110226366B

CN110226366B - Electromagnetic wave shielding film, shielded printed wiring board, and electronic device

Info

Publication number: CN110226366B
Application number: CN201880010126.3A
Authority: CN
Inventors: 上农宪治; 山内志朗; 白发润; 村川昭
Original assignee: Tuozda Wire Co ltd; DIC Corp
Current assignee: Tuozda Wire Co ltd; DIC Corp
Priority date: 2017-02-08
Filing date: 2018-02-07
Publication date: 2021-02-12
Anticipated expiration: 2038-02-07
Also published as: WO2018147298A1; KR102267570B1; KR20190117494A; JPWO2018147298A1; TW201836464A; TWI760431B; JP6564534B2; CN110226366A

Abstract

An object of the present invention is to provide an electromagnetic wave shielding film which is difficult to degrade in shielding properties when manufacturing a shielded printed wiring board, and which has sufficient folding endurance. The electromagnetic wave shielding film of the present invention comprises: a conductive adhesive layer, a shielding layer laminated on the conductive adhesive layer, and an insulating layer laminated on the shielding layer, characterized in that: the shielding layer is Several openings are formed, the opening area of the openings is 70 to 71000 μm ² , and the opening ratio of the openings is 0.05 to 3.6%.

Description

Electromagnetic wave shielding film, shielded printed wiring board, and electronic device

Technical Field

The invention relates to an electromagnetic wave shielding film, a shielded printed wiring board, and an electronic apparatus.

Background

Conventionally, an electromagnetic wave shielding film is attached to a printed wiring board such as a flexible printed wiring board (FPC) to shield an electromagnetic wave from the outside.

Generally, an electromagnetic wave shielding film includes a conductive adhesive layer, a shielding layer made of a metal thin film or the like, and an insulating layer laminated in this order. The electromagnetic wave shielding film is thermally pressed in a state of being superimposed on the printed wiring board, whereby the electromagnetic wave shielding film is bonded to the printed wiring board through the adhesive layer to manufacture a shielded printed wiring board. After the bonding, the components are mounted on the printed wiring board by solder reflow. In addition, the printed wiring board has a structure in which a printed pattern on a base film is covered with an insulating film.

When the shielded printed wiring board is manufactured, gas is generated from the conductive adhesive layer of the electromagnetic wave shielding film, the insulating film of the printed wiring board, and the like when the shielded printed wiring board is heated by hot pressing or solder reflow. In addition, when the base film of the printed wiring board is formed of a resin having high hygroscopicity such as polyimide, water vapor may be generated from the base film by heating. These volatile components generated from the conductive adhesive layer, the insulating film, and the base film cannot pass through the shielding layer, and therefore are accumulated between the shielding layer and the conductive adhesive layer. Therefore, when the solder reflow process is rapidly heated, the interlayer adhesiveness between the shield layer and the conductive adhesive layer may be broken due to volatile components accumulated between the shield layer and the conductive adhesive layer, and the shield characteristics may be degraded.

In order to solve the above-described problems, patent document 1 describes an electromagnetic wave shielding film having a shielding layer (metal thin film) provided with a plurality of openings to improve air permeability.

When the shielding layer has a plurality of openings, even if a volatile component is generated, the volatile component can pass through the shielding layer through the openings. Therefore, it is possible to prevent volatile components from accumulating between the shield layer and the conductive adhesive layer, and to prevent the shield property from being lowered due to the destruction of the close adhesion between the layers.

[ Prior art documents ]

[ patent document ]

[ patent document 1] International publication No. 2014/192494.

Disclosure of Invention

[ problem to be solved by the invention ]

However, the electromagnetic wave shielding film described in patent document 1 has an opening in the shielding layer, and therefore the strength of the shielding layer is weak.

Therefore, when the electromagnetic wave shielding film described in patent document 1 is used for a flexible printed wiring board, the following problems occur.

That is, the flexible printed wiring board is repeatedly bent during use. The electromagnetic wave shielding film used for such a flexible printed wiring board and the shielding layer of the electromagnetic wave shielding film are repeatedly bent.

As described above, the electromagnetic wave shielding film described in patent document 1 has a problem that the shielding layer is easily broken when repeatedly bent because the shielding layer has a weak strength.

In view of the above problems, an object of the present invention is to provide an electromagnetic wave shielding film having sufficient folding endurance, in which shielding characteristics are not easily degraded in manufacturing a shielded printed wiring board.

[ MEANS FOR SOLVING THE PROBLEMS ] A method for producing a semiconductor device

In order to solve the above technical problems, the inventors of the present invention have earnestly studied and found that: the present inventors have completed the present invention by controlling the opening area of the opening portion and the opening ratio of the opening portion of the shielding layer formed on the electromagnetic wave shielding film, thereby preventing the shielding characteristics of the shielded printed wiring board manufactured using the electromagnetic wave shielding film from being lowered and further improving the folding endurance of the shielded printed wiring board.

That is, the electromagnetic wave shielding film of the present invention comprises a conductive adhesive layer, a shielding layer laminated on the conductive adhesive layer, and a shield laminated on the shieldAn insulating layer over the capping layer, characterized by: a plurality of openings having an opening area of 70 to 71000 μm are formed in the shield layer²And the aperture ratio of the opening part is 0.05-3.6%.

In the electromagnetic wave shielding film of the present invention, the shielding layer is formed with a plurality of openings. Therefore, in the hot pressing step, the solder reflow step, and the like in the production of a shielded printed wiring board using the electromagnetic wave shielding film of the present invention, even if a volatile component is generated between the shielding layer and the conductive adhesive layer, the volatile component can pass through the opening of the shielding layer.

Therefore, volatile components are not easily accumulated between the shield layer and the conductive adhesive layer. This prevents the interlayer adhesiveness from being broken.

In the electromagnetic wave shielding film of the present invention, the opening area of the opening is 70 to 71000 μm²And the aperture ratio of the opening part is 0.05-3.6%.

When the opening area and the opening ratio of the opening formed in the shield layer are within these ranges, the folding resistance is sufficient, and the accumulation of volatile components between the shield layer and the conductive adhesive layer can be prevented.

The opening area of the opening is less than 70 μm²If the opening is too narrow, the volatile component is less likely to pass through the shield layer. In this way, volatile components are likely to accumulate between the shield layer and the conductive adhesive layer. Therefore, when the electromagnetic wave shielding film is used to manufacture a shielded printed wiring board, the interlayer adhesiveness between the shielding layer and the conductive adhesive layer is easily broken. Thus, the shielding characteristics are degraded.

The opening area of the opening is more than 71000 μm²If the opening is too wide, the shielding layer becomes weak, and the folding endurance is lowered.

If the aperture ratio of the opening is less than 0.05%, the proportion of the opening is too small, and the volatile component is not easily passed through the shield layer. In this way, volatile components are likely to accumulate between the shield layer and the conductive adhesive layer.

If the aperture ratio of the opening exceeds 3.6%, the ratio of the opening becomes too large, the shielding layer becomes weak, and the folding endurance is lowered.

In the present specification, the "aperture ratio" refers to a total opening area of the plurality of openings with respect to an area of the entire main surface of the shield layer.

In the electromagnetic wave shielding film of the present invention, it is preferable that the opening pitch of the opening portion is 10 to 10000 μm.

When the opening pitch of the openings is less than 10 μm, the ratio of the openings in the entire shield layer is large. This weakens the shielding layer, and the folding endurance is lowered.

When the opening pitch of the openings exceeds 10000 μm, the ratio of the openings in the entire shield layer is small. Thus, the volatile component is less likely to pass through the shield layer, and the volatile component is likely to accumulate between the shield layer and the conductive adhesive layer.

In the present specification, the "opening pitch of the openings" refers to a distance between centers of gravity between adjacent and closest openings.

In the electromagnetic wave shielding film of the present invention, the thickness of the shielding layer is preferably 0.5 μm or more.

If the thickness of the shielding layer is less than 0.5 μm, the shielding property is lowered because the shielding layer is too thin.

In the electromagnetic wave shielding film of the present invention, the shielding layer preferably includes a copper layer.

Copper is a suitable material for the shield layer from the viewpoint of conductivity and economy.

In the electromagnetic wave shielding film of the present invention, a preferable technical solution is: the shielding layer further comprises a silver layer, the silver layer is disposed on the insulating layer side, and the copper layer is disposed on the conductive adhesive layer side.

The electromagnetic wave shielding film having such a structure can be easily manufactured by coating a silver paste on an insulating layer, forming an opening as a silver layer, and plating copper on the silver layer.

The electromagnetic wave-shielding film of the present invention is preferably used for a flexible printed wiring board.

As described above, the electromagnetic wave shielding film of the present invention is less likely to accumulate volatile components between the shielding layer and the conductive adhesive layer when manufacturing a shielded printed wiring board. In addition, the electromagnetic wave shielding film of the present invention has sufficient folding endurance. Therefore, even if the electromagnetic wave shielding film of the present invention is used for a flexible printed wiring board and repeatedly bent, it is not easily broken.

Therefore, the electromagnetic wave-shielding film of the present invention is suitably used as an electromagnetic wave-shielding film for a flexible printed wiring board.

The shielded printed wiring board of the present invention comprises: a printed wiring board including a base member on which a printed circuit is formed, an insulating film provided on the base member and covering the printed circuit, and an electromagnetic wave shielding film provided on the printed wiring board, characterized in that: the electromagnetic wave shielding film is the electromagnetic wave shielding film of the present invention.

In the shielded printed wiring board according to the present invention, the printed wiring board is preferably a flexible printed wiring board.

The shielded printed wiring board of the present invention includes the electromagnetic wave shielding film of the present invention having sufficient folding endurance. Therefore, the shielded printed wiring board of the present invention also has sufficient folding endurance.

The electronic device of the present invention is characterized in that: the electronic device is assembled with the shielding printed wiring board of the present invention, and the shielding printed wiring board is assembled in a bent state.

As described above, the shielded printed wiring board of the present invention has sufficient folding endurance. Therefore, the electronic device is not easily broken even when assembled in a bent state. Therefore, the electronic apparatus of the present invention can reduce the space for disposing the shield printed wiring board.

Therefore, the electronic apparatus of the present invention can be thinned.

[ Effect of the invention ]

In the electromagnetic wave shielding film of the present invention, a plurality of openings having an opening area of 70 to 71000 μm are formed in a shielding layer²And the aperture ratio of the opening portion is 0.05 to 3.6%.

When the feature of the opening formed in the shielding layer is within this range, the folding endurance is sufficient, and when the electromagnetic wave shielding film of the present invention is used to manufacture a shielded printed wiring board, it is possible to prevent volatile components from accumulating between the shielding layer and the conductive adhesive layer.

Drawings

Fig. 1 is a schematic cross-sectional view of an example of the electromagnetic wave shielding film of the present invention;

fig. 2 (a) and (b) are schematic views of a case where a shielded printed wiring board is manufactured using an electromagnetic wave-shielding film in which an opening portion is not formed in a shielding layer;

fig. 3 (a) to (c) are schematic plan views showing an example of an arrangement pattern of openings in a shield layer constituting the electromagnetic wave shielding film of the present invention;

FIG. 4 is a schematic cross-sectional view of an example of an electromagnetic wave shielding film of the present invention in which the shielding layer includes a copper layer and a silver layer;

fig. 5 (a) to (c) are schematic sequential process views illustrating an example of the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 6 is a process diagram illustrating an example of an insulating layer preparation process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 7 is a schematic view illustrating an example of a silver paste printing process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 8 is a schematic view showing an example of a silver paste printing process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 9 is a schematic view showing an example of a silver paste printing process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 10 (a) and (b) are process diagrams showing an example of a copper plating process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 11 (a) and (b) are process diagrams showing an example of a conductive adhesive layer forming process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

fig. 12 is a schematic diagram of the structure of a system used in the KEC method.

Detailed Description

The electromagnetic wave shielding film of the present invention will be specifically described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within a range not changing the gist of the present invention.

Fig. 1 is a schematic cross-sectional view of an example of an electromagnetic wave shielding film of the present invention.

As shown in fig. 1, the electromagnetic wave shielding film 10 includes a conductive adhesive layer 20, a shielding layer 30 laminated on the conductive adhesive layer 20, and an insulating layer 40 laminated on the shielding layer 30.

In addition, the shield layer 30 is formed with a plurality of openings 50.

(conductive adhesive layer)

In the electromagnetic wave shielding film 10, the conductive adhesive layer 20 may be made of any material as long as it has conductivity and can function as an adhesive.

For example, the conductive adhesive layer 20 may be made of conductive particles and a bonding resin composition.

The conductive particles are not particularly limited, and may be metal fine particles, carbon nanotubes, carbon fibers, metal fibers, or the like.

When the conductive particles are metal particles, the metal particles are not particularly limited, and may be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder obtained by silver plating of copper powder, particles obtained by coating polymer particles with metal, glass beads, or the like.

Among them, copper powder or silver-coated copper powder which is inexpensive is preferable from the viewpoint of economy.

The average particle diameter of the conductive particles is not particularly limited, but is preferably 0.5 to 15.0. mu.m. When the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity of the conductive adhesive layer is good. When the average particle diameter of the conductive particles is 15.0 μm or less, the conductive adhesive layer can be made thin.

The shape of the conductive particles is not particularly limited, and can be appropriately selected from spherical, flat, scaly, dendritic, rod-like, fibrous, and the like.

The material of the adhesive resin composition is not particularly limited, and a thermoplastic resin composition such as a styrene-based resin composition, a vinyl acetate-based resin composition, a polyester-based resin composition, a polyethylene-based resin composition, a polypropylene-based resin composition, an imide-based resin composition, an amide-based resin composition, or an acrylic resin composition, a thermosetting resin composition such as a phenol-based resin composition, an epoxy-based resin composition, a polyurethane-based resin composition, a melamine-based resin composition, or an alkyd-based resin composition, or the like can be used.

The material of the adhesive resin composition may be 1 kind of the above materials alone, or may be a combination of 2 or more kinds.

The conductive adhesive layer 20 may contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity improver, and the like, as needed.

The amount of the conductive particles in the conductive adhesive layer 20 is not particularly limited, but is preferably 15 to 80% by mass, and more preferably 15 to 60% by mass.

Within the above range, the bondability of the conductive adhesive layer to the printed wiring board is improved.

The thickness of the conductive adhesive layer 20 is not particularly limited, and may be appropriately set as needed, and is preferably 0.5 to 20.0 μm.

When the thickness of the conductive adhesive layer is less than 0.5 μm, it is difficult to obtain good conductivity. When the thickness of the conductive adhesive layer exceeds 20.0. mu.m, the thickness of the entire electromagnetic wave shielding film becomes thick and difficult to handle.

In addition, the conductive adhesive layer 20 preferably has anisotropic conductivity.

When the conductive adhesive layer 20 has anisotropic conductivity, the transmission characteristics of a high-frequency signal transmitted through a signal circuit of a printed wiring board are improved as compared with the case where the conductive adhesive layer has isotropic conductivity.

(insulating layer)

In the electromagnetic wave shielding film 10, the insulating layer 40 is not particularly limited as long as it has sufficient insulating properties and can protect the conductive adhesive layer 20 and the shielding layer 30, and is preferably made of, for example, a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, or the like.

The thermoplastic resin composition is not particularly limited, and examples thereof include styrene resin compositions, vinyl acetate resin compositions, polyester resin compositions, polyethylene resin compositions, polypropylene resin compositions, imide resin compositions, and acrylic resin compositions.

The thermosetting resin composition is not particularly limited, and examples thereof include phenol resin compositions, epoxy resin compositions, polyurethane resin compositions, melamine resin compositions, alkyd resin compositions, and the like.

The active energy ray-curable composition is not particularly limited, and examples thereof include polymerizable compounds having at least 2 (meth) acryloyloxy groups in the molecule.

The insulating layer 40 may be made of 1 material alone, or 2 or more materials.

The insulating layer 40 may also contain a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity modifier, an anti-blocking agent, and the like, as necessary.

The thickness of the insulating layer 40 is not particularly limited, and can be set as appropriate as needed, and is preferably 1 to 15 μm, and more preferably 3 to 10 μm.

When the thickness of the insulating layer 40 is less than 1 μm, it is too thin to sufficiently protect the conductive adhesive layer 20 and the shield layer 30.

If the thickness of the insulating layer 40 exceeds 15 μm, the electromagnetic wave shielding film 10 is too thick, and the insulating layer 40 itself is easily broken. Therefore, it is difficult to apply the composition to a member requiring folding resistance.

(Shielding layer)

Before describing a shielding layer of an electromagnetic wave shielding film of the present invention, a case of manufacturing a shielded printed wiring board using an electromagnetic wave shielding film in which an opening portion is not formed in the shielding layer will be described with reference to the drawings.

Fig. 2 (a) and (b) are schematic views showing a case where a shielded printed wiring board is manufactured using an electromagnetic wave shielding film in which an opening portion is not formed in a shielding layer.

As shown in fig. 2 (a), when manufacturing a shielded printed wiring board, the shielded printed wiring board on which the electromagnetic wave shielding film 510 is disposed is heated by hot pressing and solder reflow.

By this heating, volatile components 560 are generated from the conductive adhesive layer 520 of the electromagnetic wave-shielding film 510, the insulating film of the printed wiring board, the base film, and the like.

When the sheet is heated rapidly in this state, as shown in fig. 2 (b), the volatile component 560 accumulated between the shield layer 530 and the conductive adhesive layer 520 may break the close adhesion between the shield layer 530 and the conductive adhesive layer 520.

However, in the electromagnetic wave shielding film 10, the shielding layer 30 has a plurality of openings 50.

Therefore, when the electromagnetic wave shielding film 10 is used to manufacture a shielded printed wiring board, even if a volatile component is generated between the shielding layer 30 and the conductive adhesive layer 20 by heating, the volatile component can pass through the opening 50 of the shielding layer 30.

Therefore, volatile components are less likely to accumulate between the shield layer 30 and the conductive adhesive layer 20. This prevents the interlayer adhesiveness from being broken.

In the electromagnetic wave shielding film 10, the opening area of the opening 50 is 70 to 71000 μm²And the aperture ratio of the opening 50 is 0.05 to 3.6%.

Preferably, the opening area of the opening 50 is 70 to 32000 mu m²More preferably 70 to 10000 μm²More preferably 80 to 8000 mu m²。

The aperture ratio of the opening 50 is preferably 0.1 to 3.6%.

When the opening area and the opening ratio of the opening 50 formed in the shield layer 30 are within these ranges, the folding resistance is sufficient, and the accumulation of volatile components between the shield layer 30 and the conductive adhesive layer 20 can be prevented.

The opening area of the opening of the shield layer is less than 70 μm²When the opening is too narrow, the volatility is highThe components do not readily pass through the barrier layer. In this way, volatile components are likely to accumulate between the shield layer and the conductive adhesive layer.

The opening area of the opening of the shield layer exceeds 71000 μm²If the opening is too wide, the shielding layer becomes weak, and the folding endurance is lowered.

If the aperture ratio of the openings of the shield layer is less than 0.05%, the proportion of the openings is too small, and volatile components are not likely to pass through the shield layer. In this way, volatile components are likely to accumulate between the shield layer and the conductive adhesive layer.

If the aperture ratio of the openings of the shield layer exceeds 3.6%, the ratio of the openings becomes too large, the shield layer becomes weak, and the folding endurance is lowered.

The shape of the opening 50 in the electromagnetic wave shielding film 10 is not particularly limited, and may be circular, oval, racetrack, triangular, tetragonal, pentagonal, hexagonal, octagonal, star-shaped, and the like.

Among them, a circular shape is preferable in terms of ease of forming the opening 50.

The shape of the plurality of openings 50 may be 1 type alone or a combination of a plurality of types.

In the electromagnetic wave shielding film 10, the opening pitch of the openings 50 is preferably 10 to 10000 μm, more preferably 25 to 2000 μm, and still more preferably 250 to 2000 μm.

The pattern of the openings 50 in the electromagnetic wave-shielding film 10 is not particularly limited, and may be, for example, the following pattern.

Fig. 3 (a) to (c) are schematic plan views of examples of the arrangement pattern of the openings in the shielding layer constituting the electromagnetic wave shielding film of the present invention.

As shown in fig. 3 (a), the arrangement pattern of the openings 50 may be an arrangement pattern in which the centers of the openings 50 are located at the vertices of a regular triangle in a plane in which the regular triangle is continuously arranged in the horizontal and vertical directions.

As shown in fig. 3 (b), the arrangement pattern of the openings 50 may be an arrangement pattern in which the centers of the openings 50 are located at the vertices of a square in a plane in which the squares are continuously arranged in the horizontal and vertical directions.

As shown in fig. 3 (c), the pattern of the openings 50 may be such that the centers of the openings 50 are located at the vertices of regular hexagons in a plane in which regular hexagons are arranged in series in the horizontal and vertical directions.

In the electromagnetic wave shielding film 10, the thickness of the shielding layer 30 is preferably 0.5 μm or more, and more preferably 1.0 μm or more. The thickness of the shield layer 30 is preferably 10 μm or less.

When the thickness of the shield layer 30 is 1.0 μm or more, the transmission characteristics are good in a signal transmission system for transmitting a high-frequency signal having a frequency of 0.01 to 10 GHz.

Further, when the opening is not formed in the shield layer, if the shield layer is thick, the interlayer adhesion between the shield layer and the conductive adhesive layer is easily broken in the production of the shield printed wiring board. Particularly, if the thickness of the shield layer 30 exceeds 1.0 μm, the interlayer close adhesion is significantly deteriorated. However, in the electromagnetic wave shielding film 10, since the opening 50 is formed in the shielding layer 30, the interlayer adhesiveness between the shielding layer 30 and the conductive adhesive layer 20 can be prevented from being broken.

The electromagnetic wave shielding film of the present invention is preferably used in a signal transmission system for transmitting signals having a frequency of 0.01 to 10 GHz.

In the electromagnetic wave shielding film of the present invention, the shielding layer may be made of any material as long as it has electromagnetic wave shielding properties, and may be made of, for example, a metal layer.

The shielding layer may comprise a layer made of gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc, etc., preferably a copper layer.

In addition, the shielding layer may include a layer made of an alloy of the metals.

In addition, the shielding layer may be laminated by several metal layers.

It is particularly preferred that the shielding layer comprises a copper layer and a silver layer.

The following description will discuss a case where the shielding layer includes a copper layer and a silver layer.

Fig. 4 is a schematic cross-sectional view of an example of the electromagnetic wave shielding film of the present invention in which the shielding layer includes a copper layer and a silver layer.

The electromagnetic wave shielding film 110 shown in fig. 4 includes a conductive adhesive layer 120, a shielding layer 130 laminated on the conductive adhesive layer 120, and an insulating layer 140 laminated on the shielding layer 130.

The shield layer 130 includes a copper layer 132 and a silver layer 131, the silver layer 131 is disposed on the insulating layer 140 side, and the copper layer 132 is disposed on the conductive adhesive layer 120 side.

The electromagnetic wave shielding film 110 having such a structure can be easily manufactured by coating the insulating layer 140 with silver paste, forming an opening as a silver layer, and plating the silver layer with copper.

(other structures)

In the electromagnetic wave shielding film of the present invention, an anchor coat layer may be formed between the insulating layer and the shielding layer.

Examples of the material of the anchor coat layer include urethane resin, acrylic resin, core-shell type composite resin having a urethane resin as a shell and an acrylic resin as a core, epoxy resin, imide resin, amide resin, melamine resin, phenol resin, urea-formaldehyde resin, blocked isocyanate obtained by reacting polyisocyanate with a blocking agent such as phenol, polyvinyl alcohol, and polyvinyl pyrrolidone.

The electromagnetic wave shielding film of the present invention may include a support film on the insulating layer side, or may include a release film on the conductive adhesive layer side. When the electromagnetic wave shielding film includes a support film and a release film, the electromagnetic wave shielding film of the present invention can be handled easily in the work of transporting the electromagnetic wave shielding film of the present invention, manufacturing a shielded printed wiring board or the like using the electromagnetic wave shielding film of the present invention.

In addition, when the electromagnetic wave shielding film of the present invention is disposed to shield a printed wiring board or the like, the support film and the release film are peeled off.

The electromagnetic wave shielding film of the present invention can be used for any purpose as long as the purpose of shielding electromagnetic waves is achieved.

In particular, the electromagnetic wave shielding film of the present invention is preferably used for a printed wiring board, and particularly preferably used for a flexible printed wiring board.

The shielded printed wiring board thus containing the electromagnetic wave shielding film of the present invention is the shielded printed wiring board of the present invention.

Namely, the shield printed wiring board of the present invention includes: a printed wiring board including a base member on which a printed circuit is formed, an insulating film provided on the base member and covering the printed circuit, and an electromagnetic wave shielding film provided on the printed wiring board, characterized in that: the electromagnetic wave shielding film is the electromagnetic wave shielding film of the present invention.

Further, it is preferable that the printed wiring board is a flexible printed wiring board.

The shielding printed wiring board of the present invention contains the electromagnetic wave shielding film of the present invention having sufficient folding endurance. Therefore, the shielded printed wiring board of the present invention also has sufficient folding endurance.

The shielded printed wiring board of the present invention is incorporated in an electronic device for use.

In particular, the electronic device in which the shielded printed wiring board of the present invention is assembled in a bent state is the electronic device of the present invention.

Therefore, the electronic apparatus of the present invention can be thinned.

(method for producing electromagnetic wave shielding film)

Next, a method for manufacturing the electromagnetic wave shielding film of the present invention will be described. The electromagnetic wave shielding film of the present invention is not limited to the following method.

First, an example of a method for manufacturing the electromagnetic wave shielding film 10, which is an example of the electromagnetic wave shielding film of the present invention, will be described.

The method for producing the electromagnetic wave shielding film 10 includes (1) a shielding layer forming step, (2) an insulating layer forming step, and (3) a conductive adhesive layer forming step.

These steps are described in detail below with reference to the drawings.

Fig. 5 (a) to (c) are schematic sequential process views of an example of the method for producing an electromagnetic wave shielding film of the present invention.

(1) Step of Forming Shielding layer

First, as shown in FIG. 5 (a), a sheet 35 having electromagnetic wave shielding properties is prepared, and an opening 50 is formed in the sheet 35 such that the opening area of the opening 50 is 70 to 71000 μm²And the aperture opening ratio is 0.05-3.6%, and the shielding layer 30 is manufactured.

The opening 50 can be formed by punching, laser irradiation, or the like.

In addition, when the sheet 35 is made of copper or the like, it can be designed to: a resist is disposed on the surface of the sheet 35, and the resist is patterned to form the opening 50.

In addition, it is also possible to design: a conductive paste or a paste functioning as a plating catalyst is printed on the surface of the sheet 35.

In this printing, it can be designed that: the opening 50 is formed by printing in a predetermined pattern.

When the paste functioning as the plating catalyst is printed, it is preferable to form the opening 50 by printing the paste and then form a metal film by an electroless plating method or an electroplating method to form the shield layer.

The paste functioning as the plating catalyst can be a fluid containing a metal such as nickel, copper, chromium, zinc, gold, silver, aluminum, tin, cobalt, palladium, lead, platinum, cadmium, and rhodium.

(2) Step of Forming insulating layer

Next, as shown in fig. 5 (b), an insulating layer 40 is formed by applying and curing an insulating layer resin composition 45 to one surface of the shield layer 30.

Examples of the method for coating the resin composition for an insulating layer include conventionally known coating methods such as a gravure coating method, a kiss coating method, a slot coating method, a lip coating method, a comma coating method, a blade coating method, a roll coating method, a knife coating method, a spray coating method, a bar coating method, a spin coating method, and a dip coating method.

The method of curing the resin composition for an insulating layer can employ various conventionally known methods depending on the kind of the resin composition for an insulating layer.

(3) Conductive adhesive layer formation step

Next, as shown in fig. 5 (c), the conductive adhesive layer composition 25 is applied to the surface of the shield layer 30 opposite to the surface on which the insulating layer 40 is formed, thereby forming the conductive adhesive layer 20.

Examples of the method for applying the composition 25 for a conductive adhesive layer include conventionally known coating methods such as a gravure coating method, a kiss coating method, a slot coating method, a lip coating method, a comma coating method, a blade coating method, a roll coating method, a knife coating method, a spray coating method, a bar coating method, a spin coating method, and a dip coating method.

Through the above steps, the electromagnetic wave shielding film 10, which is an example of the electromagnetic wave shielding film of the present invention, can be manufactured.

Next, an example of the electromagnetic wave shielding film of the present invention, that is, an example of a method for manufacturing the electromagnetic wave shielding film 110 in which the shielding layer includes a copper layer and a silver layer, will be described.

The method for manufacturing the electromagnetic wave shielding film 110 includes (1) an insulating layer preparation step, (2) a silver paste printing step, (3) a copper plating step, and (4) a conductive adhesive layer forming step.

These steps will be described in detail below with reference to fig. 6 to 11.

(1) Preparation process of insulating layer

Fig. 6 is a process diagram illustrating an example of the insulating layer preparation process in the method for manufacturing an electromagnetic wave shielding film according to the present invention.

First, as shown in fig. 6, an insulating layer 140 is prepared.

The insulating layer 140 can be prepared by a conventional method.

(2) Printing step (silver paste printing step) of metal-containing fluid as plating catalyst

Next, silver paste 133 was printed as a plating catalyst on one main surface of the insulating layer 140. At this time, the silver paste is formed to have an opening area of 70 to 71000 μm²And a plurality of openings 150 having an opening ratio of 0.05 to 3.6%.

Examples of the method of printing the silver paste 133 include a gravure printing such as rotogravure printing, a relief printing such as flexographic printing, a screen printing method, an offset printing method in which a pattern is formed by gravure printing, relief printing, screen printing, and the like and then transferred, and a method in which ink jet printing of a plate is not required.

A method of printing the silver paste 133 by rotogravure printing will be described below.

FIGS. 7 to 9 are process diagrams showing an example of a silver paste printing process in the method for manufacturing an electromagnetic wave shielding film according to the present invention;

first, as shown in fig. 7, a roll-shaped plate roll 70 having a plurality of columnar projections 72 formed on the surface thereof is prepared. At this time, the process of the present invention,the area of the upper side surface 73 of each protrusion 72 is 70 to 71000 μm². And the plurality of protrusions 72 are provided such that the ratio of the total area of the upper side surfaces 73 of the plurality of protrusions 72 to the surface area of the plate roll 70 is 0.05 to 3.6%.

The surface of the plate roll on which the projections 72 are not formed is the non-projection forming region 71.

The surface area of the plate roll 70 means a total value of the area of the non-protrusion-forming region 71 of the plate roll 70 in which the protrusions 72 are not formed and the total area of the upper side surfaces 73 of the plurality of protrusions 72.

Next, as shown in fig. 8, silver paste 133 is caused to enter the non-projecting portion forming region 71. At this time, the silver paste 133 is not applied to the upper side surface 73 of the protrusion 72.

Then, as shown in fig. 9, the insulating layer 140 is passed between the platen roller 70 having the silver paste 133 and the platen roller 75, and the silver paste 133 is printed on one main surface of the insulating layer 140.

In this printing, the portion of the insulating layer 140 where the protrusion 72 touches can be used as the opening 150 without printing the silver paste 133.

The silver paste 133 printed on the insulating layer 140 becomes the silver layer 131.

The silver paste 133 may contain any of silver particles, and may contain various additives such as a dispersant, a thickener, a leveling agent, and an antifoaming agent.

The shape of the silver particles is not particularly limited, and any shape such as spherical, flaky, dendritic, needle-like, and fibrous can be used.

The silver particles are preferably in the form of particles, and are preferably of a nano size. Specifically, the silver particles preferably have an average particle diameter in the range of 1 to 100nm, and more preferably 1 to 50 nm.

In the present specification, the "average particle diameter" refers to a volume average value measured by a dynamic light scattering method after silver particles are diluted in a dispersion solvent.

For this measurement, "Nanotrac UPA-150" manufactured by Microtrac corporation can be used.

The thickness of the silver layer formed by the printed silver paste is preferably 5 to 200 nm.

(3) Copper plating step

Fig. 10 (a) and (b) are process diagrams showing an example of the copper plating step in the method for producing an electromagnetic wave shielding film of the present invention.

Next, as shown in fig. 10 (a) and (b), copper is plated on the silver layer 131 to form a copper layer 132 on the silver layer 131.

The plating method of copper is not particularly limited, and conventional electroless plating and electroplating can be used.

When copper is plated by electroless plating, it is preferable to use a plating solution containing copper sulfate, a reducing agent, and a solvent such as an aqueous medium or an organic solvent.

In the case of copper plating by the electroplating method, it is preferable to use a plating solution containing copper sulfate, sulfuric acid, and an aqueous medium, and adjust the plating treatment time, current density, and the amount of the plating additive to be used so as to achieve a desired copper thickness.

The thickness of the plated copper is preferably 0.1 to 10 μm.

Through the above steps, the shield layer 130 including the silver layer 131 and the copper layer 132 can be formed.

(4) Conductive adhesive layer formation step

Fig. 11 (a) and (b) are process diagrams showing an example of the step of forming the conductive adhesive layer in the method of manufacturing the electromagnetic wave shielding film of the present invention.

In fig. 11 (a) and (b), the subsequent steps are shown with fig. 10 (b) turned upside down.

Next, as shown in fig. 11 (a) and (b), a composition 125 for a conductive adhesive layer is applied on the copper layer 132 to form a conductive adhesive layer 120.

Examples of the method for applying the composition 125 for a conductive adhesive layer include conventionally known coating methods, such as a gravure coating method, a kiss coating method, a slot coating method, a lip coating method, a comma coating method, a blade coating method, a roll coating method, a knife coating method, a spray coating method, a bar coating method, a spin coating method, and a dip coating method.

Through the above steps, the electromagnetic wave shielding film 110, which is an example of the electromagnetic wave shielding film of the present invention, can be manufactured.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Preparation example 1 preparation example of silver paste

Silver particles having an average particle diameter of 30nm were dispersed in a mixed solvent of 35 parts by mass of ethanol and 65 parts by mass of ion-exchanged water using a polyethyleneimine compound as a dispersant, thereby obtaining a silver paste having a silver concentration of 15% by mass.

(example 1)

(1) Preparation process of insulating layer

An insulating layer made of epoxy resin having a thickness of 5 μm was prepared.

(2) Silver paste printing process

Next, by the method shown in FIGS. 7 to 9, silver paste was printed on one main surface of the insulating layer using a roll-shaped plate roll to form an opening having an area of 79 μm²And a plurality of openings having an aperture ratio of 0.15% and an opening pitch of 250 μm, thereby forming a silver layer.

In addition, the thickness of the silver layer was 50 nm.

The silver paste obtained in preparation example 1 was used.

The openings are circular in shape, and the arrangement pattern of the openings is such that the center of each opening is located at the apex of a regular triangle in a plane in which the regular triangles are continuously arranged in the horizontal and vertical directions.

(3) Copper plating step

Next, the insulating layer after the silver paste printing was immersed in an electroless copper plating solution ("ARG coater", manufactured by ohye pharmaceutical corporation, ph 12.5) at 55 ℃ for 20 minutes, to form an electroless copper plating film (thickness 0.5 μm) on the silver layer.

Next, the surface of the obtained electroless copper plating film was set as a cathode, phosphorus-containing copper was set as an anode, and a plating solution containing copper sulfate was used at a current density of 2.5A/dm²Electroplating for 30 minutes under the conditionAnd a copper plating layer having a total thickness of 1 μm was laminated on the silver layer. As the plating solution, a solution of copper sulfate 70 g/liter, sulfuric acid 200 g/liter, chloride ion 50 mg/liter, and TOP LUCINA SF (Bright material made by Orye pharmaceutical industries, Ltd.) 5 g/liter was used.

(4) Conductive adhesive layer formation step

A conductive adhesive layer, which was prepared by adding 20 mass% of Ag-in-Cu powder to a phosphorus-containing epoxy resin, was applied to the copper layer to a thickness of 15 μm.

The coating method uses a lip coating mode.

Through the above steps, the electromagnetic wave-shielding film of example 1 was produced.

Examples 2 to 36 and comparative examples 1 to 30

Electromagnetic wave shielding films of examples 2 to 36 and comparative examples 1 to 30 were produced in the same manner as in example 1, except that the opening area, the aperture ratio, the aperture pitch, and the thickness of the copper layer of the openings were changed as shown in tables 1 and 2.

[ Table 1]

[ Table 2]

(evaluation of electromagnetic wave shielding characteristics)

The electromagnetic wave shielding properties of the electromagnetic wave shielding films according to the examples and comparative examples were evaluated by the KEC method using an electromagnetic wave shielding effect measurement device 80 developed by the general community KEC, the electronics industry, japan.

Fig. 12 is a schematic diagram of the structure of a system used in the KEC process.

The system used in the KEC method includes an electromagnetic wave shielding effect measuring apparatus 80, a spectrum analyzer 91, an attenuator 92 that performs attenuation of 10dB, an attenuator 93 that performs attenuation of 3dB, and a preamplifier 94.

As shown in fig. 12, in the electromagnetic wave shielding effect measurement apparatus 80, 2 measurement jigs 83 are provided to face each other. The electromagnetic wave shielding films according to the examples and comparative examples (indicated by reference numeral 110 in fig. 12) were interposed between the measuring jigs 83. The measurement jig 83 has a size distribution of TEM cells (Transverse electric Magnetic cells) introduced therein, and is divided into bilaterally symmetrical parts in a plane perpendicular to the direction of the transport axis. However, in order to prevent the short circuit due to the insertion of the electromagnetic wave shielding film 110, the flat plate-shaped center conductor 84 is disposed with a gap between them with respect to the measurement jigs 83.

In the key method, first, a signal output from the spectrum analyzer 91 is input to the measurement jig 83 on the transmission side via the attenuator 92, and then, the measurement jig 83 on the reception side receives the signal, the signal passed through the attenuator 93 is amplified by the preamplifier 94, and then the signal level is measured by the spectrum analyzer 91. The spectrum analyzer 91 outputs the attenuation amount when the electromagnetic wave shielding film 110 is set in the electromagnetic wave shielding effect measurement device 80, based on the state where the electromagnetic wave shielding film 110 is not set in the electromagnetic wave shielding effect measurement device 80.

The electromagnetic wave shielding films according to the examples and comparative examples were cut into 15cm squares using the above-mentioned apparatus at a temperature of 25 ℃ and a relative humidity of 30 to 50%, and electromagnetic wave shielding characteristics of 200MHz were measured and evaluated.

The evaluation criteria are as follows. The results are shown in tables 1 and 2.

O: is more than 85 dB.

X: less than 85 dB.

(evaluation of interlayer peeling)

The electromagnetic wave shielding films according to the examples and comparative examples were evaluated by the following methods.

First, each electromagnetic wave shielding film is attached to the printed wiring board by hot pressing.

Then, the shielded printed wiring board was left in a clean room at 23 ℃ and 63% RH for 7 days, and then was exposed to reflow conditions to evaluate the presence or absence of interlayer peeling. In addition, the temperature condition at the time of reflow soldering was set to lead-free solder and a temperature profile of up to 265 ℃. In addition, with respect to the presence or absence of interlayer peeling, the presence or absence of swelling was evaluated by visual observation after subjecting the shielded printed wiring board to atmospheric reflow for 5 times.

O: the barrier film did not swell at all.

X: the shielding film bulges.

(evaluation of folding endurance)

Each electromagnetic wave shielding film was attached to both sides of a polyimide film having a thickness of 50 μm by hot pressing, and cut into pieces having a size of 130mm × 15mm in length × width, and the folding resistance of each piece was measured by using an MIT folding fatigue tester (manufactured by yoda seiko corporation, No.307 MIT folding fatigue tester) based on JIS P8115: 2001, the folding endurance was measured by the method specified in the specification.

The test conditions are as follows.

Bending the front end R of the clamp: 0.38mm

Bending angle: plus or minus 135 degree

Bending speed: 175cpm

Loading: 500gf

The detection method comprises the following steps: and sensing the disconnection of the shielding film through a built-in electric communication device.

The folding endurance evaluation criteria are as follows. The results are shown in tables 1 and 2.

Very good: the number of bending times is more than 2000, and the broken wire is generated.

O: the number of bending times is more than 600 and less than 2000, and the broken wire is generated.

X: the number of bending times is less than 600 times, and the broken wire is generated.

As shown in tables 1 and 2, the opening area of the opening portion was 70 to 71000 μm as in the electromagnetic wave shielding films of the examples²The aperture ratio of the opening is 0.When the content is 05 to 3.6%, all of the evaluation of electromagnetic wave shielding properties, the evaluation of interlayer peeling, and the evaluation of folding endurance were good.

[ NUMBER DEFINITION ]

10. 110 electromagnetic wave shielding film

20. 120 conductive adhesive layer

25. 125 conductive adhesive layer composition

30. 130 shield layer

40. 140 insulating layer

45 resin composition for insulating layer

50. 150 opening part

70 printing roller

71 non-protrusion forming region

72 projection part

73 upper side of the protrusion

75 pressure roller

80 electromagnetic wave shielding effect measuring device

83 measuring clamp

84 center conductor

91 spectrum analyzer

92. 93 attenuator

94 preamplifier

131 Ag layer

132 copper layer

133 silver paste

Claims

1. An electromagnetic wave shielding film comprising a conductive adhesive layer, a shielding layer laminated on the conductive adhesive layer, and an insulating layer laminated on the shielding layer, characterized in that:

the shielding layer is formed with a plurality of opening portions,

the opening portions are regularly arranged at fixed intervals,

the opening area of the opening part is 70-71000 μm²，

The aperture ratio of the opening portion is 0.05-3.6%.

2. The electromagnetic wave shielding film according to claim 1, characterized in that:

the opening pitch of the opening part is 10-10000 μm.

3. The electromagnetic wave shielding film according to claim 1 or 2, characterized in that:

the thickness of the shielding layer is more than 0.5 μm.

4. The electromagnetic wave shielding film according to claim 1 or 2, characterized in that:

the shielding layer includes a copper layer.

5. The electromagnetic wave shielding film according to claim 4, characterized in that:

the shielding layer further comprises a silver layer,

the silver layer is disposed on the side of the insulating layer,

the copper layer is disposed on the conductive adhesive layer side.

6. The electromagnetic wave shielding film according to claim 1 or 2, characterized in that:

the electromagnetic wave shielding film is used for a flexible printed wiring board.

7. A shielded printed wiring board, comprising:

a printed wiring board including a base member on which a printed circuit is formed, an insulating film provided on the base member and covering the printed circuit,

an electromagnetic wave shielding film disposed on the printed wiring board,

the method is characterized in that: the electromagnetic wave shielding film according to any one of claims 1 to 6.

8. The shielded printed wiring board of claim 7, wherein:

the printed wiring board is a flexible printed wiring board.

9. An electronic device, characterized in that: the electronic apparatus is assembled with the shield printed wiring board described in claim 7 or 8, and the shield printed wiring board is assembled in a bent state.