TW202009283A - Electromagnetic wave shielding film with transfer film, manufacturing method thereof and manufacturing method of shielded printed wiring board with which it is difficult to generate gap between shielding film and printed wiring board - Google Patents

Abstract

The present invention provides an electromagnetic wave shielding film with a transfer film, with which it is difficult to generate a gap between an adhesive layer of an electromagnetic wave shielding film and a surface of a printed wiring board when manufacturing a shielded printed wiring board. The electromagnetic wave shielding film with a transfer film comprises a transfer film and an electromagnetic wave shielding film laminated on the transfer film, which is characterized in that: the electromagnetic wave shielding film is provided with: a protective layer in contact with the transfer film, a shield layer laminated on the protective layer, and a an adhesive layer laminated on the shield layer, wherein the Young's modulus of the transfer film is 2.0 GPa or more.

Description

Method for manufacturing electromagnetic wave shielding film with transfer film, method for manufacturing electromagnetic wave shielding film with transfer film, and method for manufacturing shielded printed wiring board

Field of invention The invention relates to a manufacturing method of an electromagnetic wave shielding film with a transfer film, an electromagnetic wave shielding film with a transfer film, and a manufacturing method of a shielded printed wiring board.

Background technique In electronic devices such as mobile phones, video cameras, and notebook computers, which are rapidly becoming smaller and more functional, flexible printed wiring boards are mostly used in order to fit circuits into complex mechanisms. In addition, using its excellent flexibility, it can also be used in the connection between the movable part such as the printing head and the control part. In these electronic instruments, electromagnetic wave shielding measures are required. In the flexible printed wiring boards used in the device, flexible printed wiring boards with electromagnetic wave shielding measures have also been used (hereinafter also referred to as "shielded printed wiring board").

For example, Patent Document 1 discloses a method for manufacturing a shielded printed wiring board, which is coated with an electromagnetic wave shielding film on a base film containing a printed circuit. The method for manufacturing a shielded printed wiring board described in Patent Document 1 discloses that when covering an electromagnetic wave shielding film, a shielding layer and a conductive adhesive layer (adhesive layer) are provided on one side of a cover film (protective layer), and Attach a peelable adhesive film (transfer film) on the other side to form a reinforced shielding film (electromagnetic wave shielding film with transfer film), and contact the base film with a conductive adhesive layer Method, the reinforcing shielding film is placed, and the adhesive film is peeled off after heating, pressurizing, and the like.

Prior technical literature Patent Literature Patent Document 1: Japanese Patent Laid-Open No. 2000-269632

Summary of the invention Problems to be solved by invention As described above, the electromagnetic wave shielding film will stick to the printed wiring board through the adhesive layer of the electromagnetic wave shielding film. The surface of the printed wiring board that is in contact with the adhesive layer is usually not flat but has a level difference. The adhesive layer has plasticity, so it can fill the height difference of the surface of the printed wiring board to a certain extent, but it can not be completely buried and there may be gaps. Such gaps can cause various problems.

As an example of such a problem, the case where the ground circuit of the printed wiring board is connected to the external ground through the electromagnetic wave shielding film will be described below. The basic structure of the printed wiring board includes: a base film, a printed circuit formed on the base film and including a ground circuit, and a cover layer covering the printed circuit. In order to electrically connect the ground circuit to the external ground, a hole exposing the ground circuit may be formed in the cover layer on the ground circuit. The hole exposing the ground circuit will become the level difference of the surface of the printed wiring board. As described above, the electromagnetic wave shielding film will stick to the printed wiring board through the adhesive layer of the electromagnetic wave shielding film. In addition, in this case, in order to electrically connect the ground circuit to the external ground, the adhesive layer of the electromagnetic wave shielding film will make the conductive adhesive layer of the tool. When the electromagnetic wave shielding film is adhered to the printed wiring board, the adhesive layer of the electromagnetic wave shielding film deforms or flows to fill the hole exposing the ground circuit (that is, the height difference of the surface of the printed wiring board). However, if the aperture of the exposed ground circuit is small, the adhesive layer of the electromagnetic wave shielding film cannot fully fill the hole exposing the ground circuit, and there may be a case where the ground circuit and the adhesive layer of the electromagnetic wave shielding film cannot sufficiently contact. In this case, there is a problem that the connection resistance increases.

The present invention is made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film with a transfer film, which can make the adhesive layer of the electromagnetic wave shielding film and the surface of the printed wiring board when manufacturing a shielded printed wiring board There is no gap between them.

Means to solve the problem That is, the electromagnetic wave shielding film with a transfer film of the present invention is composed of a transfer film and an electromagnetic wave shielding film laminated on the transfer film, characterized in that the electromagnetic wave shielding film includes a protective layer in contact with the transfer film, The shield layer laminated on the protective layer and the adhesive layer laminated on the shield layer; the Young's modulus of the transfer film is 2.0 GPa or more.

When the electromagnetic wave shielding film with a transfer film of the present invention is used to manufacture a shielded printed wiring board, the adhesive layer of the electromagnetic wave shielding film with a transfer film is abutted and pressed against the surface of the printed wiring board. At this time, if the Young's modulus of the transfer film is 2.0 GPa or more, the transfer film is hard enough, and therefore the pressure bonding pressure is not easily dispersed. Therefore, even if there is a level difference on the surface of the printed wiring board, the adhesive layer of the electromagnetic wave shielding film can be firmly pressed, and the adhesive layer can sufficiently fill the level difference.

In the electromagnetic wave shielding film with a transfer film of the present invention, the adhesive layer may have conductivity. Generally, the printed circuit on the printed wiring board is also provided with a ground circuit. When the adhesive layer of the electromagnetic wave shielding film with transfer film of the present invention has conductivity, the electromagnetic wave shielding film is arranged on the printed wiring board in such a manner that the adhesive layer of the electromagnetic wave shielding film is in contact with the ground circuit Isoelectric connection. Furthermore, by electrically connecting the adhesive layer of the electromagnetic wave shielding film to the external ground, the ground circuit can be electrically connected to the external ground. In addition, when the adhesive layer of the electromagnetic wave shielding film is brought into contact with the ground circuit, a hole exposing the ground circuit (that is, the height difference of the surface of the printed wiring board) is formed in the cover layer on the ground circuit. If the electromagnetic wave shielding film with a transfer film of the present invention is used, the adhesive layer of the electromagnetic wave shielding film can sufficiently contact the ground circuit, and therefore, the connection resistance between the adhesive layer of the electromagnetic wave shielding film and the ground circuit can be prevented from increasing.

In the electromagnetic wave shielding film with a transfer film of the present invention, the shielding layer may be composed of a metal layer. Furthermore, in the electromagnetic wave shielding film with a transfer film of the present invention, the shielding layer may be made of conductive resin. Accordingly, in the electromagnetic wave shielding film with a transfer film of the present invention, as long as it can shield electromagnetic waves, the material of the shielding layer is not particularly limited.

Another electromagnetic wave shielding film with a transfer film of the present invention is composed of a transfer film and an electromagnetic wave shielding film laminated on the transfer film, characterized in that the electromagnetic wave shielding film includes a protective layer in contact with the transfer film, And a conductive adhesive layer deposited on the protective layer; the Young's modulus of the transfer film is 2.0 GPa or more.

In the electromagnetic wave shielding film with a transfer film of the present invention, the Young's modulus of the transfer film is 2.0 GPa or more. That is, the transfer film is hard enough. Therefore, when the electromagnetic wave shielding film is crimped to the printed wiring board, the pressure is not easily dispersed. Therefore, even if there is a level difference on the surface of the printed wiring board, the adhesive layer of the electromagnetic wave shielding film can be firmly pressed, and the adhesive layer can sufficiently fill the level difference. In addition, in the electromagnetic wave shielding film with a transfer film of the present invention, the conductive adhesive layer has both the electromagnetic wave shielding function and the bonding function with the printed wiring board.

In addition, when the adhesive layer of the electromagnetic wave shielding film is brought into contact with the ground circuit, a hole exposing the ground circuit (that is, the height difference of the surface of the printed wiring board) is formed in the cover layer on the ground circuit. If the electromagnetic wave shielding film with a transfer film of the present invention is used, the adhesive layer of the electromagnetic wave shielding film can sufficiently contact the ground circuit, and therefore, the connection resistance between the adhesive layer of the electromagnetic wave shielding film and the ground circuit can be prevented from increasing.

The method for manufacturing an electromagnetic wave shielding film with a transfer film of the present invention is characterized by including the following steps: a transfer film preparation step, preparing a transfer film with a Young's modulus of 2.0 GPa or more; and an electromagnetic wave shielding film forming step, in which the above transfer An electromagnetic wave shielding film is formed by sequentially laminating a protective layer, a shielding layer, and an adhesive layer on the film. In addition, another method for manufacturing an electromagnetic wave shielding film with a transfer film of the present invention includes the following steps: a transfer film preparation step, preparing a transfer film having a Young's modulus of 2.0 GPa or more; and an electromagnetic wave shielding film forming step, An electromagnetic wave shielding film is formed by sequentially depositing a protective layer and an adhesive layer made of conductive resin and having an electromagnetic wave shielding function on the transfer film. By this method, the electromagnetic wave shielding film with the transfer film of the present invention described above can be manufactured.

The manufacturing method of the shielded printed wiring board of the present invention is characterized by comprising the following steps: A printed wiring board preparation step to prepare a printed wiring board including: a base film, a printed circuit formed on the base film and including a ground circuit, and a cover layer covering the printed circuit; The preparation step of the electromagnetic wave shielding film with a transfer film prepares the electromagnetic wave shielding film with a transfer film of the present invention; In the pressure bonding step, the adhesive layer of the electromagnetic wave shielding film with the transfer film is arranged in contact with the cover layer of the printed wiring board, and the electromagnetic wave shielding film with the transfer film is pressure bonded to the printed wiring board; and Peeling step, peeling the transfer film from the electromagnetic wave shielding film with the transfer film; In addition, the surface of the cover layer in contact with the adhesive layer has a step difference.

As described above, the electromagnetic wave shielding film with transfer film of the present invention has a Young's modulus of 2.0 GPa or more and is sufficiently hard. Therefore, even when there is a level difference on the surface of the cover layer of the printed wiring board, the adhesive layer of the electromagnetic wave shielding film can be firmly pressed, and the adhesive layer can sufficiently fill the level difference.

In the method for manufacturing a shielded printed wiring board of the present invention, the height difference is preferably a hole exposing the ground circuit, and the adhesive layer is preferably electrically conductive. As described above, in the method for manufacturing a shielded printed wiring board of the present invention, the adhesive layer can sufficiently fill the height difference. Especially when the height difference is a hole exposing the ground circuit and the adhesive layer has conductivity, the adhesive layer can be sufficiently brought into contact with the ground circuit. Therefore, the increase in connection resistance can be suppressed.

Forms for carrying out the invention Hereinafter, the electromagnetic wave shielding film with a transfer film of the present invention will be specifically described. However, the present invention is not limited to the following embodiments, and can be appropriately changed and applied within the scope of not changing the gist of the present invention.

(First embodiment) Using the drawings, the electromagnetic wave shielding film with a transfer film according to the first embodiment of the present invention will be described in detail. 1 is a cross-sectional view schematically showing an example of an electromagnetic wave shielding film with a transfer film according to the first embodiment of the present invention.

As shown in FIG. 1, the electromagnetic wave shielding film 10 with a transfer film is composed of a transfer film 20 and an electromagnetic wave shielding film 30 laminated on the transfer film 20. In addition, the electromagnetic wave shielding film 30 includes a protective layer 31 in contact with the transfer film 20, a shielding layer 32 laminated on the protective layer 31, and an adhesive layer 33 laminated on the shielding layer 32.

In addition, the Young's modulus of the transfer film 20 is 2.0 GPa or more. In addition, the lower limit of the Young's modulus of the transfer film 20 is preferably 2.5 GPa, and more preferably 2.7. In addition, the upper limit of the Young's modulus of the transfer film 20 is preferably 5.0 GPa, and more preferably 4.5. If the Young's modulus of the transfer film is greater than 5.0 GPa, when the electromagnetic wave shielding film with the transfer film is adhered to the printed wiring board, the followability of the height difference is likely to decrease.

The electromagnetic wave shielding film 10 with a transfer film is adhered to the printed wiring board for manufacturing the shielded printed wiring board. When the electromagnetic wave shielding film 10 with a transfer film is used to manufacture a shielded printed wiring board, the adhesive layer 33 of the electromagnetic wave shielding film 10 with a transfer film is contacted and pressed against the surface of the printed wiring board. At this time, if the Young's modulus of the transfer film 20 is 2.0 GPa or more, since the transfer film 20 is hard enough, the pressure bonding pressure is not easily dispersed. Therefore, even when there is a level difference on the surface of the printed wiring board, the adhesive layer 33 of the electromagnetic wave shielding film 30 can be firmly pressed, and the adhesive layer 33 can sufficiently fill the level difference.

Next, the structure of each layer forming the electromagnetic wave shielding film 10 with a transfer film will be described.

(Transfer film) The material of the transfer film is not particularly limited as long as the Young's modulus of the transfer film can be 2.0 GPa or more, and examples include polyethylene terephthalate, polyethylene naphthalate, and polyvinyl fluoride , Polydifluoroethylene, Rigid Polyvinyl Chloride, Polyvinylidene Chloride, Nylon, Polyimide, Polystyrene, Polyvinyl Alcohol, Ethylene-Vinyl Alcohol Copolymer, Polycarbonate, Polyacrylonitrile, Polyethylene Butene, soft polyvinyl chloride, polydifluoroethylene, polyethylene, polypropylene, polyurethane, ethylene vinyl acetate copolymer, polyvinyl acetate and other plastic sheets, cellophane, Dowling paper, kraft paper, Papers such as coated paper, various non-woven fabrics, synthetic paper, metal layers, or composite films incorporating these. In addition, the transfer film may also be thermosetting resin or thermoplastic resin, but thermoplastic resin is preferred. If it is a thermoplastic resin, the electromagnetic wave shielding film with a transfer film easily attaches to the height difference of the printed wiring board. The transfer film can also be a single-sided or double-sided film that has been subjected to a release treatment. The release treatment method can be exemplified by applying a release agent to one or both sides of the film, or performing a matting treatment in a physical manner method.

In addition, when the transfer film is made of a plastic sheet, in order to adjust the Young's modulus, it may contain inorganic particles such as titanium oxide or silicon dioxide, or organic particles having a core-shell structure.

The thickness of the transfer film is preferably 10 to 150 μm, and more preferably 20 to 100 μm, and particularly preferably 40 to 60 μm. If the thickness of the transfer film is less than 10 μm, the transfer film may break when the shielded printed wiring board is manufactured, and it is not easy to peel off from the electromagnetic wave shielding film. If the thickness of the transfer film is greater than 150 μm, it is not easy to handle.

An adhesive layer for transfer film may also be provided between the transfer film and the protective layer. In this case, the transfer film will be in a state where it is bonded by the adhesive layer for the transfer film. The transfer film must be easily peelable from the electromagnetic wave shielding film when the electromagnetic wave shielding film is used. The adhesive layer for the transfer film should be made to remain on the transfer film side when the transfer film is peeled off.

(The protective layer) The protective layer is not particularly limited as long as it is insulating and can protect the adhesive layer and the shielding layer. For example, it is preferably composed of 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-based resin compositions, vinyl acetate-based resin compositions, polyester-based resin compositions, polyethylene-based resin compositions, and polypropylene-based resin compositions. Acetylene imide resin composition, acrylic resin composition, etc.

The above-mentioned thermosetting resin composition is not particularly limited, and examples thereof include epoxy resin-based resin compositions, urethane-based resin compositions, urethane-urea-based resin compositions, and styrene-based resins. At least one resin composition in the group consisting of a composition, a phenol resin composition, a melamine resin composition, an acrylic resin composition, and an alkyd resin composition.

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

The protective layer may be composed of a single material or two or more materials.

In the protective layer, it can also contain hardening accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, UV absorbers, defoamers, leveling agents, fillers, flame retardants, viscosity adjustment Agents, anti-caking agents, etc.

The thickness of the protective layer is not particularly limited, and can be set appropriately according to the needs, preferably 1~15μm, and more preferably 3~10μm. If the thickness of the protective layer is less than 1 μm, it will not be easy to fully protect the adhesive layer and the shielding layer because it is too thin. If the thickness of the protective layer is greater than 15 μm, the electromagnetic wave shielding film may not be easily bent due to the excessive thickness, and the protective layer itself may be easily damaged. Therefore, it is not easy to apply to members requiring bending resistance.

An anchor coating layer can also be formed between the protective layer and the shielding layer. Examples of the material of the anchor coating layer include urethane resin, acrylic resin, core-shell composite resin with urethane resin as the shell and acrylic resin as the core, epoxy resin, amide imide resin, Acrylate resin, melamine resin, phenol resin, urea-formaldehyde resin, blocked isocyanate, polyvinyl alcohol, polyvinylpyrrolidone, etc. obtained by reacting a blocking agent such as phenol with polyisocyanate.

(Shield) In the electromagnetic wave shielding film 10 with a transfer film of FIG. 1, the shielding layer 32 may be composed of a metal layer, or may be composed of conductive resin. As for the electromagnetic wave shielding film 10 with a transfer film, as long as it can shield electromagnetic waves, the material of the shielding layer is not particularly limited.

When the shielding layer is composed of a metal layer, the metal layer may include a layer body composed of materials such as gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, and zinc, and it is desirable to include a copper layer. From the viewpoint of conductivity and economy, copper is an appropriate material for the shield layer.

In addition, the shielding layer may include a layered body made of an alloy of the above metals. In addition, the shielding layer may use metal foil, or may be a metal film formed by sputtering, electroless plating, electroplating, or the like.

When the shield layer is composed of conductive resin, the shield layer may be composed of conductive particles and resin.

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

When the conductive particles are metal fine particles, the metal fine particles are not particularly limited, and can be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder coated with silver on copper powder, and metal coated polymer Fine particles such as fine particles or glass beads. Among these, from the economic point of view, it is preferable to be copper powder or silver-coated copper powder that can be obtained cheaply.

The average particle size of the conductive particles is not particularly limited, and it is preferably 0.5 to 15.0 μm. If the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity of the conductive resin becomes good. If the average particle diameter of the conductive particles is 15.0 μm or less, the conductive resin can be thinned.

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

The amount of conductive particles blended is not particularly limited, but it is preferably 15 to 80% by mass, and more preferably 15 to 60% by mass.

The resin is not particularly limited, and examples thereof include: styrene-based resin composition, vinyl acetate-based resin composition, polyester-based resin composition, polyethylene-based resin composition, polypropylene-based resin composition, and amide-imide system Thermoplastic resin compositions such as resin compositions, amide-based resin compositions, acrylic-based resin compositions; and phenol-based resin compositions, epoxy-based resin compositions, urethane-based resin compositions, melamine-based resin compositions , Alkyd resin composition and other thermosetting resin composition.

(Adhesive layer) The adhesive layer may be composed of a thermosetting resin or a thermoplastic resin.

Examples of thermosetting resins include phenol resins, epoxy resins, urethane resins, melamine resins, polyamide resins, and alkyd resins. Examples of the thermoplastic resin include styrene-based resin, vinyl acetate-based resin, polyester-based resin, polyethylene-based resin, polypropylene-based resin, amide-imide-based resin, and acrylic-based resin. In addition, the epoxy resin is more preferably modified amide epoxy resin. Such resins are suitable as the resin constituting the adhesive layer.

The thickness of the adhesive layer is not particularly limited, preferably 1-50 μm, and more preferably 3-30 μm. If the thickness of the adhesive layer is less than 1 μm, the amount of resin constituting the adhesive layer is small, so it is difficult to obtain sufficient adhesive performance. Also, it will easily break. If the thickness of the adhesive layer is greater than 50 μm, the entire body becomes thicker, and the flexibility is easily lost.

The adhesive layer may also have conductivity. Generally, the printed circuit on the printed wiring board is also provided with a ground circuit. When the adhesive layer of the electromagnetic wave shielding film with transfer film of the present invention has conductivity, the electromagnetic wave shielding film is arranged on the printed wiring board in such a manner that the adhesive layer of the electromagnetic wave shielding film is in contact with the ground circuit Isoelectric connection. Furthermore, by electrically connecting the adhesive layer of the electromagnetic wave shielding film to the external ground, the ground circuit can be electrically connected to the external ground. In addition, when the adhesive layer of the electromagnetic wave shielding film is brought into contact with the ground circuit, a hole exposing the ground circuit (that is, the height difference of the surface of the printed wiring board) is formed in the cover layer on the ground circuit. If the electromagnetic wave shielding film with a transfer film of the present invention is used, the adhesive layer of the electromagnetic wave shielding film can sufficiently contact the ground circuit, and therefore, the connection resistance between the adhesive layer of the electromagnetic wave shielding film and the ground circuit can be prevented from increasing.

When the adhesive layer has conductivity, the adhesive layer may be composed of conductive particles and resin.

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

When the conductive particles are metal fine particles, the metal fine particles are not particularly limited, and can be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder coated with silver on copper powder, and metal coated polymer Fine particles such as fine particles or glass beads. Among these, from the economic point of view, it is preferable to be copper powder or silver-coated copper powder that can be obtained cheaply.

The average particle size of the conductive particles is not particularly limited, and it is preferably 0.5 to 15.0 μm. If the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity of the conductive adhesive layer becomes good. If the average particle diameter of the conductive particles is 15.0 μm or less, the conductive adhesive layer can be thinned.

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

The amount of conductive particles blended is not particularly limited, but it is preferably 15 to 80% by mass, and more preferably 15 to 60% by mass.

The resin is not particularly limited, and examples thereof include: styrene-based resin composition, vinyl acetate-based resin composition, polyester-based resin composition, polyethylene-based resin composition, polypropylene-based resin composition, and amide-imide system Thermoplastic resin compositions such as resin compositions, amide-based resin compositions, acrylic-based resin compositions; and phenol-based resin compositions, epoxy-based resin compositions, urethane-based resin compositions, melamine-based resin compositions , Alkyd resin composition and other thermosetting resin composition.

In addition, when the adhesive layer has conductivity, it is preferable to have anisotropic conductivity. If the adhesive layer has anisotropic conductivity, the transmission characteristics of the high-frequency signal transmitted by the printed circuit of the printed wiring board will be more improved than when the adhesive layer has the isotropic conductivity.

Next, a method of manufacturing the electromagnetic wave shielding film with transfer film according to the first embodiment of the present invention will be described. The method for manufacturing an electromagnetic wave shielding film with a transfer film of the present invention includes: (1) a transfer film preparation step; and (2) an electromagnetic wave shielding film forming step.

(1) Transfer film preparation steps In this step, a transfer film having a Young's modulus of 2.0 GPa or more is prepared. The material and the like of the transfer film have already been described, so the description here is omitted.

(2) Electromagnetic wave shielding film forming steps Next, a protective layer, a shielding layer, and an adhesive layer are sequentially deposited on the transfer film to form an electromagnetic wave shielding film. The method of stacking these layers can be the same as the conventional method of manufacturing an electromagnetic wave shielding film. For example, a protective layer and a shielding layer can be formed on the transfer film, and an adhesive layer can be formed on another release film. By bonding these, an electromagnetic wave shielding film with a transfer film is produced. In addition, the materials of the protective layer, the shielding layer, and the adhesive layer have already been described, so the description here is omitted.

Through the above steps, the electromagnetic wave shielding film with a transfer film according to the first embodiment of the present invention can be manufactured.

Next, a method of manufacturing a shielded printed wiring board using the electromagnetic wave shielding film with a transfer film according to the first embodiment of the present invention will be described. The manufacturing method of a shielded printed wiring board according to the first embodiment of the present invention includes: (1) a preparation step of a printed wiring board; (2) a preparation step of an electromagnetic wave shielding film with a transfer film; (3) a crimping step; and (4) Stripping step.

Hereinafter, these steps will be described in detail using drawings. FIG. 2 is a step diagram schematically showing an example of a preparation step of a printed wiring board in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. 3 is a step diagram schematically showing an example of a preparation step of an electromagnetic wave shielding film with a transfer film in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. Fig. 4 is a step diagram schematically showing an example of the pressure bonding step in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. 5 is a step diagram schematically showing an example of a peeling step in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention.

(1) Printed wiring board preparation steps First, as shown in FIG. 2, a printed wiring board 50 is prepared. The printed wiring board 50 includes a base film 51, a printed circuit 52 formed on the base film 51 and including a ground circuit 52 a, and a cover layer 53 covering the printed circuit 52 . In the printed wiring board 50, a hole 54 is formed in the cover layer 53 to expose the ground circuit 52a, and the hole 54 has a height difference.

The base film 51, the printed circuit 52, and the cover layer 53 may be the same as those used in conventional printed wiring boards.

(2) Preparation steps of electromagnetic wave shielding film with transfer film Next, as shown in FIG. 3, the electromagnetic wave shielding film 10 with a transfer film according to the first embodiment of the present invention described above is prepared. The electromagnetic wave shielding film 10 with a transfer film is composed of a transfer film 20 and an electromagnetic wave shielding film 30 laminated on the transfer film 20. In addition, the electromagnetic wave shielding film 30 includes a protective layer 31 in contact with the transfer film 20, a shielding layer 32 laminated on the protective layer 31, and an adhesive layer 33 laminated on the shielding layer 32. In addition, the adhesive layer 33 has conductivity.

(3) Crimping steps Next, as shown in FIG. 4, the adhesive layer 33 of the electromagnetic wave shielding film 10 with a transfer film is placed in contact with the cover layer 53 of the printed wiring board 50, and the electromagnetic wave shielding film 10 with a transfer film is pressed against Printed wiring board 50.

At this time, since the adhesive layer 33 has flexibility, the hole 54 is filled. The transfer film 20 has a Young's modulus of 2.0 GPa or more. Therefore, when the electromagnetic wave shielding film 30 is pressure-bonded to the printed wiring board 50, the pressure is not easily dispersed. In this way, the adhesive layer 33 of the electromagnetic wave shielding film 30 can be firmly pressed, and the adhesive layer 33 can fully fill the hole 54. Thus, the adhesive layer 33 and the ground circuit 52a can be sufficiently contacted.

Moreover, since the adhesive layer 33 has conductivity, the ground circuit 52a and the adhesive layer 33 can be electrically connected. As described above, the adhesive layer 33 is sufficiently in contact with the ground circuit 52a, and therefore, a low connection resistance state can be formed.

In addition, after manufacturing the shielded printed wiring board, by electrically connecting the adhesive layer of the electromagnetic wave shielding film to the external ground, the ground circuit can be electrically connected to the external ground.

There are no special restrictions on the conditions during the crimping in this step. For example, the conditions are preferably pressure: 1.0 to 5.0 MPa, temperature: 140 to 190°C, and time: 15 to 90 minutes.

(4) Stripping step Next, as shown in FIG. 5, the transfer film 20 is peeled off from the electromagnetic wave shielding film 10 with the transfer film attached. There are no special restrictions on the stripping method, and conventional methods can be used.

Through the above steps, the shielded printed wiring board 60 can be manufactured.

The manufacturing method of the shielded printed wiring board according to the first embodiment of the present invention described above is to form the hole 54 in the cover layer 53 as a height difference, however, the manufacturing method of the shielded printed wiring board of the present invention may also form a simple height on the cover layer difference. Moreover, in this case, the adhesive layer of the electromagnetic wave shielding film with the transfer film may not have conductivity.

(Second embodiment) Next, using the drawings, the electromagnetic wave shielding film with a transfer film according to the second embodiment of the present invention will be described in detail.

6 is a cross-sectional view schematically showing an example of an electromagnetic wave shielding film with a transfer film according to a second embodiment of the present invention. As shown in FIG. 6, the electromagnetic wave shielding film 110 with a transfer film is composed of the transfer film 120 and the electromagnetic wave shielding film 130 laminated on the transfer film 120. In addition, the electromagnetic wave shielding film 130 includes a protective layer 131 in contact with the transfer film 120 and a conductive adhesive layer 133 stacked on the protective layer 131 and having conductivity.

In addition, the Young's modulus of the transfer film 120 is 2.0 GPa or more. In addition, the lower limit of the Young's modulus of the transfer film 120 is preferably 2.5 GPa, and more preferably 2.7 GPa. In addition, the upper limit of the Young's modulus of the transfer film 120 is preferably 5.0 GPa, and more preferably 4.5 GPa. If the Young's modulus of the transfer film is greater than 5.0 GPa, when the electromagnetic wave shielding film with the transfer film is adhered to the printed wiring board, the followability of the height difference is likely to decrease.

The electromagnetic wave shielding film 110 with transfer film can be adhered to the printed wiring board for manufacturing the shielded printed wiring board. When the electromagnetic wave shielding film 110 with a transfer film is used to manufacture a shielded printed wiring board, the adhesive layer 133 of the electromagnetic wave shielding film 110 with a transfer film is abutted and pressed against the surface of the printed wiring board. At this time, if the Young's modulus of the transfer film 120 is 2.0 GPa or more, since the transfer film 120 is hard enough, the pressure bonding pressure is not easily dispersed. Therefore, even if there is a level difference on the surface of the printed wiring board, the adhesive layer 133 of the electromagnetic wave shielding film 130 can be firmly pressed, and the adhesive layer 133 can sufficiently fill the level difference.

In addition, in the electromagnetic wave shielding film 110 with a transfer film, the adhesive layer 133 has conductivity and also has an electromagnetic wave shielding function. That is, in the electromagnetic wave shielding film 110 with a transfer film, the adhesive layer 133 has both the electromagnetic wave shielding function and the adhesion function with the printed wiring board.

Generally, the printed circuit on the printed wiring board is also provided with a ground circuit. Since the adhesive layer of the electromagnetic wave shielding film with the transfer film has conductivity, the electromagnetic wave shielding film is arranged on the printed wiring board in such a manner that the adhesive layer of the electromagnetic wave shielding film is in contact with the ground circuit. Electrical connection. Furthermore, by electrically connecting the adhesive layer of the electromagnetic wave shielding film to the external ground, the ground circuit can be electrically connected to the external ground. In addition, when the adhesive layer of the electromagnetic wave shielding film is brought into contact with the ground circuit, a hole exposing the ground circuit (that is, the height difference of the surface of the printed wiring board) is formed in the cover layer on the ground circuit. If the electromagnetic wave shielding film with a transfer film of the present invention is used, the adhesive layer of the electromagnetic wave shielding film can sufficiently contact the ground circuit, and therefore, the connection resistance between the adhesive layer of the electromagnetic wave shielding film and the ground circuit can be prevented from increasing.

The adhesive layer 133 may be composed of conductive particles and resin.

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

When the conductive particles are metal fine particles, the metal fine particles are not particularly limited, and can be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder coated with silver on copper powder, and metal coated polymer Fine particles such as fine particles or glass beads. Among these, from the economic point of view, it is preferable to be copper powder or silver-coated copper powder that can be obtained cheaply.

The average particle size of the conductive particles is not particularly limited, and it is preferably 0.5 to 15.0 μm. If the average particle diameter of the conductive particles is 0.5 μm or more, the conductivity of the conductive adhesive layer becomes good. If the average particle diameter of the conductive particles is 15.0 μm or less, the conductive adhesive layer can be thinned.

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

The amount of conductive particles blended is not particularly limited, but it is preferably 15 to 80% by mass, and more preferably 15 to 60% by mass.

The resin is not particularly limited, and examples thereof include: styrene-based resin composition, vinyl acetate-based resin composition, polyester-based resin composition, polyethylene-based resin composition, polypropylene-based resin composition, and amide-imide system Thermoplastic resin compositions such as resin compositions, amide-based resin compositions, acrylic-based resin compositions; and phenol-based resin compositions, epoxy-based resin compositions, urethane-based resin compositions, melamine-based resin compositions , Alkyd resin composition and other thermosetting resin composition.

In addition, the ideal materials for the transfer film 120 and the protective layer 131 of the electromagnetic wave shielding film 110 with the transfer film are the same as the ideal materials for the transfer film 20 and the protective layer 31 of the electromagnetic wave shielding film 10 with the transfer film , So the description here is omitted.

Next, a method of manufacturing an electromagnetic wave shielding film with a transfer film according to a second embodiment of the present invention will be described. The method for manufacturing an electromagnetic wave shielding film with a transfer film of the present invention includes: (1) a transfer film preparation step; and (2) an electromagnetic wave shielding film forming step.

(1) Transfer film preparation steps In this step, the transfer film material and the like for preparing a transfer film having a Young's modulus of 2.0 GPa or more have already been described, so the description here is omitted.

(2) Electromagnetic wave shielding film forming steps Next, a protective layer and an adhesive layer are sequentially deposited on the transfer film to form an electromagnetic wave shielding film. The method of stacking these layers can be the same as the conventional method of manufacturing an electromagnetic wave shielding film. In addition, these materials and the like have already been explained, so the explanation here is omitted.

Examples The following shows more specific embodiments of the present invention, but the present invention is not limited to these embodiments.

(Examples 1-1 to 1-3) and (Comparative Example 1-1) (1) Transfer film preparation steps A transfer film made of polyethylene terephthalate film (Examples 1-1 to 1-3) having a Young's modulus shown in Table 1 and having a thickness of 50 μm, and a polymethylpentane having a thickness of 50 μm were prepared A transfer film made of olefin (Comparative Example 1-1). The Young's modulus is a value measured at 25°C in accordance with JIS K 7113-1995 using a tensile tester (manufactured by Shimadzu Corporation, trade name AGS-X50S).

(2) Electromagnetic wave shielding film forming steps A release agent is coated on the surface of the transfer film and heated and dried to form a release agent layer. An epoxy-based resin was prepared as a composition for a protective layer, and the epoxy-based resin was coated on the surface of the release agent layer using a wire rod, and then dried by heating to form a protective layer with a thickness of 5 μm. Next, using vacuum evaporation, a shield layer made of silver with a thickness of 0.1 μm was formed on the surface of the protective layer. Next, to the epoxy resin, dendritic silver-coated copper powder having an average particle diameter of 5 μm was added as a conductive filler and reached 15% by mass to prepare a composition for an adhesive layer. Furthermore, after applying the composition for the adhesive layer on the shield layer with a wire rod, drying was performed at 100° C. for 3 minutes to form an anisotropic conductive adhesive layer with a thickness of 15 μm. Through the above steps, electromagnetic wave shielding films with transfer films of Examples 1-1 to 1-3 and Comparative Example 1-1 were produced.

(Examples 2-1 to 2-3) and (Comparative Example 2-1) (1) Transfer film preparation steps A transfer film composed of polyethylene terephthalate film (Examples 2-1 to 2-3) having a Young's modulus shown in Table 2 and having a thickness of 50 μm, and a polymethylpentane having a thickness of 50 μm were prepared A transfer film composed of alkene (Comparative Example 2-1). The Young's modulus is a value measured at 25°C in accordance with JIS K 7113-1995 using a tensile tester (manufactured by Shimadzu Corporation, trade name AGS-X50S).

(2) Electromagnetic wave shielding film forming steps Apply a release agent to the surface of the transfer film. An epoxy-based resin was prepared as a composition for a protective layer, and the epoxy-based resin was applied to the surface of the transfer film coated with a release agent using a wire bar, and a protective layer with a thickness of 5 μm was formed by heating and drying. Next, a composition for an adhesive layer prepared by adding a dendritic silver-coated copper powder having an average particle diameter of 5 μm as a conductive filler to an epoxy resin and achieving 60% by mass. Then, after applying the composition for the adhesive layer on the protective layer with a wire rod, it was dried at 100° C. for 3 minutes to form an isotropic conductive adhesive layer with a thickness of 15 μm. Through the above steps, electromagnetic wave shielding films with transfer films of Examples 2-1 to 2-3 and Comparative Example 2-1 were produced. In addition, in the electromagnetic wave shielding films with transfer film of Examples 2-1 to 2-3 and Comparative Example 2-1, the conductive adhesive layer has both the electromagnetic wave shielding function and the bonding function with the printed wiring board .

(Creation of evaluation board) 7(a) and 7(b) are step diagrams schematically showing the method for manufacturing the evaluation substrate of Example 1. FIG. First, as shown in FIG. 7(a), on the base film 251 made of polyimide, two printed circuits 252 made of copper foil with a gold-plated layer on a part of the surface are formed and exposed A printed circuit board 250 used as a substrate for evaluation was manufactured by using a hole 254 (diameter 0.5 mm) of a printed circuit and a cover layer 253 (thickness 37.5 μm) made of a polyimide film. In addition, in the printed wiring board 250, the printed circuit 252 is an analog ground circuit.

Next, as shown in FIG. 7(b), in a manner that the adhesive layer 233 of the electromagnetic wave shielding film 210 with the transfer film of Example 1-1 contacts the cover layer 253 of the printed wiring board 250, the The electromagnetic wave shielding film 210 is arranged on the printed wiring board 250. Next, using a press, heat and pressure are applied under the conditions of temperature: 170° C., time 3 minutes, pressure: 3.0 MPa, and the electromagnetic wave shielding film with transfer film is crimped to the printed wiring board. Next, by peeling the transfer film 220, the evaluation substrate of Example 1 was produced. In addition, in FIG. 7(b), symbol 230 represents an electromagnetic wave shielding film, symbol 231 represents a protective layer, and symbol 232 represents a shielding layer.

In addition to using the electromagnetic wave shielding films with transfer films of Examples 1-2, 1-3, 2-1 to 2-3 and Comparative Examples 1-1 and 2-1, the above examples were prepared by 1 Evaluation substrate method The same method was used to produce evaluation substrates of Examples 1-2, 1-3, and 2-1 to 2-3, and Comparative Examples 1-1 and 2-1.

(Connection resistance test) 8 is a schematic diagram schematically showing a method for measuring the connection resistance of the evaluation substrate of Example 1-1 in the connection resistance test. In the evaluation substrate of Example 1-1, as shown in FIG. 8, the resistance value between two printed circuits 252 was measured using a resistance meter 270 to compare the printed circuit of the evaluation substrate and the electromagnetic wave shielding film with transfer film The connection resistance of the adhesive layer was evaluated. In addition, the printed circuit and the transfer film with the evaluation substrate of the evaluation substrates of Examples 1-2, 1-3 and 2-1 to 2-3 and Comparative Examples 1-1 and 2-1 were evaluated by the same method The connection resistance of the adhesive layer of the electromagnetic wave shielding film. Table 1 and Table 2 show the results. In addition, the case where the connection resistance in Examples 1-1 to 1-3 and Comparative Example 1-1 was less than 3000 mΩ was evaluated as excellent in conductivity, and the connection resistance in Examples 2-1 to 2-3 and Comparative Example 2-1 was evaluated When it is less than 250 mΩ, it is evaluated that the conductivity is excellent.

[Table 1]

[Table 2]

As shown in Tables 1 and 2, it can be seen that when the electromagnetic wave shielding films with transfer films of Examples 1-1 to 1-3 and Examples 2-1 to 2-3 are used, a low connection resistance state can be formed. That is, in Examples 1-1 to 1-3 and Examples 2-1 to 2-3, it was shown that the adhesive layer of the electromagnetic wave shielding film with transfer film was sufficiently in contact with the printed circuit of the evaluation substrate.

10, 110, 210 ‧‧‧ electromagnetic wave shielding film with transfer film 20, 120, 220‧‧‧ transfer film 30, 130, 230 ‧‧‧ electromagnetic wave shielding film 31, 131, 231‧‧‧ protective layer 32、232‧‧‧Shield 33, 133, 233‧‧‧ Adhesive layer 50, 250‧‧‧ printed wiring board 51, 251‧‧‧ basement membrane 52, 252‧‧‧ Printed Circuit 52a‧‧‧Ground circuit 53, 253‧‧‧ Overlay 54, 254‧‧‧ hole 60‧‧‧Shielded printed wiring board 270‧‧‧Resistance meter

1 is a cross-sectional view schematically showing an example of an electromagnetic wave shielding film with a transfer film according to the first embodiment of the present invention. FIG. 2 is a step diagram schematically showing an example of a preparation step of a printed wiring board in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. 3 is a step diagram schematically showing an example of a preparation step of an electromagnetic wave shielding film with a transfer film in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. Fig. 4 is a step diagram schematically showing an example of the pressure bonding step in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. 5 is a step diagram schematically showing an example of a peeling step in the method for manufacturing a shielded printed wiring board according to the first embodiment of the present invention. 6 is a cross-sectional view schematically showing an example of an electromagnetic wave shielding film with a transfer film according to a second embodiment of the present invention. 7(a) and 7(b) are step diagrams schematically showing the method for manufacturing the evaluation substrate of Example 1. FIG. 8 is a schematic diagram schematically showing a method for measuring the connection resistance of the evaluation substrate of Example 1-1 in the connection resistance test.

10‧‧‧Electromagnetic wave shielding film with transfer film

20‧‧‧Transfer film

30‧‧‧Electromagnetic shielding film

31‧‧‧Protection layer

32‧‧‧Shield

33‧‧‧ Adhesive layer

Claims (9)

An electromagnetic wave shielding film with a transfer film is composed of a transfer film and an electromagnetic wave shielding film laminated on the transfer film, and is characterized by: The electromagnetic wave shielding film includes: a protective layer in contact with the transfer film, a shielding layer laminated on the protective layer, and an adhesive layer laminated on the shielding layer; The Young's modulus of the aforementioned transfer film is 2.0 GPa or more. The electromagnetic wave shielding film with a transfer film according to claim 1, wherein the aforementioned adhesive layer has conductivity. An electromagnetic wave shielding film with a transfer film as claimed in claim 1 or 2, wherein the aforementioned shielding layer is composed of a metal layer. An electromagnetic wave shielding film with a transfer film as claimed in claim 1 or 2, wherein the aforementioned shielding layer is composed of a conductive resin. An electromagnetic wave shielding film with a transfer film is composed of a transfer film and an electromagnetic wave shielding film laminated on the transfer film, and is characterized by: The electromagnetic wave shielding film includes: a protective layer in contact with the transfer film, and a conductive adhesive layer deposited on the protective layer; The Young's modulus of the aforementioned transfer film is 2.0 GPa or more. A manufacturing method of electromagnetic wave shielding film with transfer film, which is characterized by comprising the following steps: Transfer film preparation step, prepare a transfer film with a Young's modulus of 2.0 GPa or more; and In the electromagnetic wave shielding film forming step, a protective layer, a shielding layer, and an adhesive layer are sequentially deposited on the transfer film to form an electromagnetic wave shielding film. A manufacturing method of electromagnetic wave shielding film with transfer film, which is characterized by comprising the following steps: Transfer film preparation step, prepare a transfer film with a Young's modulus of 2.0 GPa or more; and In the electromagnetic wave shielding film forming step, a protective layer, an adhesive layer composed of a conductive resin and having an electromagnetic wave shielding function are sequentially deposited on the transfer film to form an electromagnetic wave shielding film. A method for manufacturing a shielded printed wiring board, characterized in that it includes the following steps: A printed wiring board preparation step to prepare a printed wiring board including: a base film, a printed circuit formed on the base film and including a ground circuit, and a cover layer covering the printed circuit; Preparation step of electromagnetic wave shielding film with transfer film, prepare electromagnetic wave shielding film with transfer film as in any one of claims 1 to 5; In the pressure bonding step, the adhesive layer of the electromagnetic wave shielding film with the transfer film is placed in contact with the cover layer of the printed wiring board, and the electromagnetic wave shielding film with the transfer film is pressure bonded to the printed wiring board; and In the peeling step, the transfer film is peeled off from the electromagnetic wave shielding film with the transfer film; In addition, the surface of the cover layer in contact with the adhesive layer has a step difference. The method for manufacturing a shielded printed wiring board according to claim 8, wherein the height difference is a hole exposing the ground circuit, and the adhesive layer has conductivity.

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