TW201943054A - Electromagnetic wave shielding film, shielding printed circuit board and method for manufacturing shielding printed circuit capable of exhibiting high adhesive strength when an adhered member such as a reinforced plate is adhered to the isolation layer - Google Patents

Abstract

An objective of the invention is to provide an electromagnetic wave shielding film capable of exhibiting high adhesive strength when an adhered member such as a reinforced plate is adhered to an isolation layer. The electromagnetic wave shielding film of the invention has a shielding layer and an isolation layer laminated on the shielding layer. Its characteristic is that the maximum valley depth Sv on the surface of the isolation layer is above 3.0 [mu]m.

Description

Electromagnetic wave shielding film, shielding printed circuit board and manufacturing method of shielding printed circuit board

FIELD OF THE INVENTION The present invention relates to an electromagnetic wave shielding film, a shielded printed circuit board, and a method for manufacturing a shielded printed circuit board.

2. Description of the Related Art In the rapid development of miniaturized and highly functional electronic devices such as mobile phones, video cameras, and notebook computers, flexible printed circuit boards are often used to assemble circuits into complex mechanisms. Furthermore, the excellent flexibility can be used to connect the movable part and the control part like a print head. In these electronic devices, electromagnetic wave shielding measures must be taken. Among the flexible printed circuit boards used in the devices, flexible printed circuit boards with electromagnetic wave shielding measures (hereinafter also referred to as "shielded printed circuit boards") have also begun to be used. board").

Patent Document 1 describes that in the field of flexible printed circuit boards, a part of the circuit board is reinforced by a reinforcing plate to increase mechanical strength for use.
Patent Document 1 discloses an adhesive sheet that can be used for fixing such a reinforcing plate.

Prior Art Literature Patent Literature Patent Literature 1: Japanese Patent No. 4869944

SUMMARY OF THE INVENTION In the field of a shielding film, the problem to be solved by the invention is that the surface of the insulating layer of the shielding film is generally designed as a matte surface.
When the reinforcement layer is attached to the surface of such an insulation layer, the adhesion strength may be weakened. However, in the design of the shielding film, it has not been thought to consider the relationship between the adhesion strength and the reinforcement plate to control the insulation. The surface state of the layer.

Based on the above background, an object of the present invention is to provide an electromagnetic wave shielding film that exhibits high bonding strength when a bonded member such as a reinforcing plate is bonded to an insulating layer.

Means for Solving the Problem The inventors of the present invention have found that by setting the surface of the insulating layer of the electromagnetic wave shielding film to a specific surface state, a high bonding strength can be exhibited when a bonded member such as a reinforcing plate is bonded, and thus completed the present invention.

The electromagnetic wave shielding film of the present invention includes a shielding layer and an insulating layer laminated on the shielding layer, and is characterized in that the maximum valley depth Sv on the surface of the insulating layer is 3.0 μm or more.

On the surface of the insulating layer, an adhered member such as an adhesive layer and a reinforcing plate can be penetrated. However, as for the surface of the insulating layer as the bonding surface, if the index showing the state of the surface, namely, the maximum valley depth Sv is 3.0 μm or more, When a member to be bonded, such as a reinforcing plate, is then exhibited, a high bonding strength can be exhibited.

In the electromagnetic wave shielding film of the present invention, the interface expansion area ratio Sdr of the surface of the insulating layer is preferably 5.0% or more.
If the other index showing the surface state of the insulating layer, that is, the interface developed area ratio Sdr is 5.0% or more, a higher bonding strength can be exhibited when a bonded member such as a reinforcing plate is bonded.

The shielded printed circuit board of the present invention includes: a printed circuit board; the electromagnetic wave shielding film of the present invention, wherein a shielding layer is arranged on the printed circuit board side and laminated on the printed circuit board; and a bonded member, It is provided on the insulating layer of the electromagnetic wave shielding film; and the adhered member is adhered to the insulating layer of the electromagnetic wave shielding film through an adhesive layer provided on the surface of the adhered member.

The maximum wave depth Sv of the insulating layer of the electromagnetic wave shielding film of the present invention provided on the shield printed circuit board is set to be 3.0 μm or more. Then, the adhered member is adhered to the surface of the insulating layer through the adhesive layer, so that the adherence strength of the adhered member to the electromagnetic wave shielding film is improved.
Therefore, a shielded printed circuit board in which the adhered member is firmly adhered can be made.

In the shielded printed circuit board of the present invention, the adhered member is preferably a reinforcing plate.
By arranging the reinforcing plate in the shield printed circuit board where the mechanical strength is particularly desired, the mechanical strength of the place where the reinforcing plate is already arranged can be increased. In addition, since the reinforcing plate will be firmly adhered to the insulating layer of the electromagnetic wave shielding film, it will become a shielded printed circuit board, which can prevent the reinforcing plate from peeling off when the shielded printed circuit board is used, and can stably play the role of the reinforcing plate. Strengthening effect.

In the shielded printed circuit board of the present invention, the adhered member is preferably a grounding member having a connecting portion for connecting the shielding layer to the external ground, and the connecting portion of the grounding member preferably penetrates the electromagnetic wave shield. The insulating layer of the film is in contact with the shielding layer of the electromagnetic wave shielding film.
If a grounding member is used as a bonded member, it is not necessary to provide a hole or the like in the insulating layer of the electromagnetic wave shielding film in advance, and the grounding circuit can be electrically connected to the external ground at any position.
In addition, since the grounding member is firmly adhered to the insulating layer of the electromagnetic wave shielding film, it becomes a shielding printed circuit board, which can prevent the grounding member from peeling off when the shielding printed circuit board is used.

The method for manufacturing a shielded printed circuit board according to the present invention is characterized by having the following steps: for the surface of the insulating layer of the electromagnetic wave shielding film of the present invention, a method for adhering a member provided with an adhesive layer on the surface to face the insulating layer with the aforementioned adhesive layer Go on.

Through the above steps, a shielded printed circuit board having a bonded member firmly bonded to the insulating layer of the electromagnetic wave shielding film can be obtained.

In the method for manufacturing a shielded printed circuit board of the present invention, the arithmetic mean thickness Sa of the surface of the adhesive layer provided on the adhered member facing the insulating layer is preferably 0.05 to 2.0 μm.
By setting the surface provided on the adhesive layer side of the adhered member to a specific surface state, the bonding strength between the insulating layer of the electromagnetic wave shielding film and the adhered member can be further improved.

ADVANTAGE OF THE INVENTION In the electromagnetic wave shielding film of the present invention, since the surface of the insulating layer serving as a bonding surface has an index indicating the state of the surface, that is, the maximum valley depth Sv is 3.0 μm or more, a reinforcing plate is attached to the insulating layer. When the component is adhered, a high adhesive strength can be exhibited.

Forms for Implementing the Invention Hereinafter, the electromagnetic wave shielding film, the shielded printed circuit board, and the method of manufacturing the shielded printed circuit board of the present invention will be specifically described. However, the present invention is not limited to the following embodiments, and may be appropriately modified and applied without departing from the scope of the present invention.

(Electromagnetic wave shielding film)
The electromagnetic wave shielding film of the present invention can pass through the adhesive layer, and attach a member such as a reinforcing plate to the surface of the insulating layer.
In addition, since the maximum valley depth Sv, which is an index showing the surface state of the insulating layer, is 3.0 μm or more, a high bonding strength can be exhibited when a bonded member such as a reinforcing plate is bonded.

The electromagnetic wave shielding film of the present invention includes a shielding layer and an insulating layer laminated on the shielding layer.
The shielding layer is a portion for exerting electromagnetic wave shielding properties, and is a layer body having conductivity.
The insulating layer is a layer for insulating the surface of the electromagnetic wave shielding film and protecting the shielding layer.
Further, the electromagnetic wave shielding film may further include an adhesive layer, which is used to exert the adhesive force to the printed circuit board when the electromagnetic wave shielding film is adhered to the printed circuit board.
This adhesive layer is a layered body disposed on a surface opposite to the insulating layer.

FIG. 1 is a cross-sectional view schematically showing an example of a cross-section of an electromagnetic wave shielding film of the present invention.
The electromagnetic wave shielding film 10 shown in FIG. 1 includes an insulating layer 13, a shielding layer 12, and an adhesive layer 11.

On the surface of the insulating layer 13 (the surface indicated by the reference symbol A in FIG. 1), a bonded member such as a reinforcing plate may be bonded. The maximum valley depth Sv of the surface of the insulating layer is 3.0 μm or more.
In addition, the interface spread area ratio Sdr on the surface of the insulating layer is preferably 5.0% or more.
The maximum valley depth Sv on the surface of the insulating layer and the interface development area ratio Sdr on the surface of the insulating layer are parameters of surface properties set by ISO 25718-6 (2010).
These parameters can be measured using an analysis software (LMeye7) manufactured by Lasertec Corporation and provided with a surface shape measuring machine such as OPTELICS HYBRID.

The insulating layer 13 is not particularly limited as long as it has sufficient insulation and can protect the shielding layer 12. For example, the insulating layer 13 is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, an active energy ray-curable composition, and the like.
The thermoplastic resin composition is not particularly limited, and examples thereof include a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition,醯 imine resin composition, acrylic resin composition, etc.

The thermosetting resin composition is not particularly limited, and examples thereof are selected from the group consisting of an epoxy resin composition, a urethane resin composition, a urethane urea resin composition, and a styrene resin composition. , At least one resin composition in the group consisting of 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 polymerizable compounds having at least two (meth) acryloxy groups in a molecule.

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

In the insulating layer, if necessary, hardening accelerators, tackifiers, antioxidants, pigments, dyes, plasticizers, ultraviolet absorbers, defoamers, leveling agents, fillers, flame retardants, viscosity adjustment Agents, anti-caking agents, etc.

There is no particular limitation on the thickness of the insulating layer, and it can be appropriately set according to needs, and it is preferably 1 to 15 μm, and more preferably 3 to 10 μm.
If the thickness of the insulating layer is less than 1 μm, it will be difficult to sufficiently protect the adhesive layer and the shielding layer because it is too thin.
If the thickness of the insulating layer is greater than 15 μm, the electromagnetic wave shielding film will not be easily bent due to excessive thickness, and the insulating layer itself will be easily damaged. Therefore, it is not easy to be applied to a member requiring bending resistance.

An undercoat layer may also be formed between the shielding layer 12 and the insulating layer 13.
The material of the undercoat layer may be, for example, urethane resin, acrylic resin, core-shell composite resin with urethane resin as the shell and acrylic resin as the core, epoxy resin, fluorene imine resin, fluorene Amine resin, melamine resin, phenol resin, urea-formaldehyde resin, blocked isocyanate, polyvinyl alcohol, polyvinylpyrrolidone and the like obtained by reacting a blocking agent such as phenol with polyisocyanate.

The shielding layer 12 is a layered body having conductivity, and is preferably made of metal.
The shielding layer may include a layer body made of a material such as gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, and zinc, and preferably contains a copper layer.
From the viewpoint of conductivity and economy, copper is a suitable material for the shielding layer.
The shielding layer may include a layer body made of an alloy of the above-mentioned metals.
The shielding layer may be a metal foil or a metal film formed by a method such as sputtering, electroless plating, or electroplating.
The shielding layer may be a conductive adhesive layer.
The ideal composition when the shielding layer is a conductive adhesive layer may be the same as the composition of the conductive adhesive layer that can be used as the adhesive layer 11, and the adhesive layer 11 is provided separately from the shielding layer.

The adhesive layer 11 may be a conductive adhesive layer or an insulating adhesive layer.
The ideal combination of the shielding layer and the adhesive layer may be, for example, a combination of a shielding layer that is metal and an adhesive layer that is conductive, a combination of a shielding layer that is metal and an adhesive layer that is an insulating adhesive layer, and a shielding layer that is conductive A combination of a conductive adhesive layer and an adhesive layer is a conductive adhesive layer, a shielding layer is a combination of a conductive adhesive layer and an adhesive layer is an insulating adhesive layer.

The conductive adhesive layer which can be used as an adhesive layer can be composed of any material as long as it has conductivity and can function as an adhesive.
The conductive adhesive layer can be made of, for example, conductive particles and an adhesive resin composition.

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 may be silver powder, copper powder, nickel powder, solder powder, aluminum powder, silver-coated copper powder coated with silver on copper powder, and polymer coated with metal. Fine particles such as fine particles and glass beads.
Among these, from the viewpoint of economics, it is preferable to use copper powder or silver-clad copper powder which can be obtained at a low price.

The average particle diameter of the conductive particles is not particularly limited, but is preferably 0.5 to 15.0 μm. When the average particle diameter of a conductive particle is 0.5 micrometer or more, the electroconductivity of a conductive adhesive layer will become favorable. 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, scale-like, dendritic, rod-like, and fibrous.

The material of the adhesive resin composition is not particularly limited, and a styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, Thermoplastic resin composition such as fluorene resin composition, fluorene resin composition, acrylic resin composition; or phenol resin composition, epoxy resin composition, urethane resin composition, Thermosetting resin compositions such as a melamine resin composition and an alkyd resin composition.
The material of the adhesive resin composition may be one of these alone or a combination of two or more thereof.

The blending amount of the conductive particles in the conductive adhesive layer is not particularly limited, and is preferably 15 to 80% by weight, and more preferably 15 to 60% by weight.
If it is the said range, adhesiveness will improve.

The conductive adhesive layer preferably has anisotropic conductivity.
When the shielding layer 12 is a conductive adhesive layer, the conductive adhesive layer as the shielding layer 12 and the conductive adhesive layer as the adhesive layer 11 provided separately from the shielding layer 12 are both The composition can be the same or different.

The insulating adhesive layer which can be used as an adhesive layer can be composed of any material as long as it can function as an adhesive.
For example, the insulating adhesive layer may be composed of an adhesive resin composition that has been described with respect to an adhesive resin composition that can be used for the conductive adhesive layer.

The adhesive layer may optionally contain a hardening accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, a defoamer, a leveling agent, a filler, a flame retardant, and a viscosity. Conditioner, etc.

The thickness of the adhesive layer is not particularly limited, and can be appropriately set as needed, and is preferably 0.5 to 20.0 μm.
If the thickness of the adhesive layer is less than 0.5 μm, the adhesion to the printed circuit board may be insufficient.
When the thickness of the adhesive layer is more than 20.0 μm, the thickness of the entire electromagnetic wave shielding film becomes thicker, making it difficult to handle.

In the electromagnetic wave shielding film of the present invention, when the shielding layer is composed of a conductive adhesive layer, it is not necessary to provide an adhesive layer separately from the shielding layer.
Hereinafter, the form of the electromagnetic wave shielding film which consists of a conductive adhesive layer and does not differ from a shielding layer, and an adhesive layer is provided separately is demonstrated.

2 is a cross-sectional view schematically showing an example of a cross-section of an electromagnetic wave shielding film according to another embodiment of the present invention.
The electromagnetic wave shielding film 110 shown in FIG. 2 includes an insulating layer 113 and a shielding layer 112.
The structure of the insulating layer 113 may be the same as that of the insulating layer 13 in the electromagnetic wave shielding film 10 shown in FIG. 1. A bonded member such as a reinforcing plate may be adhered to the surface of the insulating layer 113. The maximum valley depth Sv of the surface of the insulating layer is 3.0 μm or more.
In addition, the interface spread area ratio Sdr on the surface of the insulating layer is preferably 5.0% or more.

As the shielding layer 112, a structure having the same structure as that in the case where the shielding layer 12 in the electromagnetic wave shielding film 10 shown in FIG. 1 is a conductive adhesive layer can be used.

(Manufacturing method of electromagnetic wave shielding film)
Next, the manufacturing method of the electromagnetic wave shielding film of this invention is demonstrated. The electromagnetic wave shielding film of the present invention is not limited to those manufactured by the method described below.

FIG. 3 (a), FIG. 3 (b), FIG. 3 (c), and FIG. 3 (d) are step diagrams, which schematically show an example of a method for manufacturing the electromagnetic wave shielding film of the present invention.
First, as shown in FIG. 3 (a), a transfer film 40 is prepared.
In the manufacturing method of an electromagnetic wave shielding film, a transfer film is a film | membrane which serves as a base material when the each layer which comprises an electromagnetic wave shielding film is laminated | stacked.

The surface of the transfer film 40 (the surface indicated by the reference symbol C in FIG. 3 (a)) is a surface for forming an insulating layer. The surface texture of the surface of the transfer film 40 is reflected on the surface texture of the insulation layer surface. Therefore, by adjusting the surface properties of the surface of the transfer film, the surface properties of the surface of the insulating layer can be adjusted.
That is, the surface properties of the surface of the transfer film are adjusted so that the maximum valley depth Sv of the surface of the insulating layer becomes 3.0 μm or more when the electromagnetic wave shielding film is formed.
In addition, it is desirable to adjust the surface properties of the surface of the transfer film so that when the electromagnetic wave shielding film is formed, the interface spread area ratio of the insulating layer surface is 5.0% or more.

The surface properties of the transfer film can be adjusted by adjusting the stretching conditions when the transfer film is produced, or roughening or smoothing the surface of the transfer film.
Examples of the transfer film that has adjusted the surface properties of the film include, for example, a sandblasted film, a kneaded film in which fine particles have been kneaded in the resin of the film, a matte coating film coated with a resin layer for adjusting surface properties, Chemically etched films, embossed films, and the like.
In order to make the maximum valley depth Sv of the surface of the insulating layer be 3.0 μm or more, the maximum valley depth Sv of the transfer film is preferably 2.5 μm or more.
In addition, in order to make the interface development area ratio Sdr on the surface of the insulating layer to be 5.0% or more, the interface development area ratio Sdr on the surface of the transfer film is preferably 15.7 μm or more.

Examples of the transfer film include: polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, rigid polyvinyl chloride, polyvinylidene chloride, nylon, polyfluorene Imine, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, soft polyvinyl chloride, polydifluoroethylene, polyethylene, polypropylene, polyurethane Ethyl acetate, ethylene vinyl acetate copolymer, polyvinyl acetate and other plastic sheets, cellophane, doolin, kraft paper, coated paper and other papers, various non-woven fabrics, synthetic papers, metal foils, or composite films combining these.
The transfer film may be a film that has been demolded on one or both sides. The demolding method may include, for example, applying a mold release agent to one or both sides of the film, or performing a matte surface physically. Method of processing.

Next, as shown in FIG. 3 (b), an insulating layer 13 is formed on the transfer film 40.
The formation of the insulating layer can be performed by applying a resin composition constituting the insulating layer.
When the resin composition constituting the insulating layer is applied, the surface properties of the transfer film are reflected on the surface properties of the resin composition.

Next, as shown in FIG. 3 (c), a shielding layer 12 is formed, and then an adhesive layer 11 is formed.
With the steps so far, the electromagnetic wave shielding film 10 formed on the transfer film 40 can be manufactured.

When the shielding layer is a metal foil, the formation of the shielding layer can be performed by sticking the metal foil; when the shielding layer is a metal film, it can be performed by a film formation method such as sputtering, electroless plating, or electroplating.
When the shielding layer is a conductive adhesive layer, it can be performed by applying a composition for a conductive adhesive layer containing a material constituting the conductive adhesive layer.
Examples of the coating method include conventionally known coating methods, such as a gravure coating method, a kiss coating method, a mold coating method, a lip coating method, a corner coating method, a blade coating method, a roll coating method, and a knife method. Coating method, spraying method, bar coating method, spin coating method, dip coating method, etc.

The formation of the adhesive layer can be performed by applying a composition for an adhesive layer containing a material constituting the adhesive layer.
The coating method can be the same as the method shown in the coating method when the conductive adhesive layer is used as the shielding layer.
In addition, FIG. 3 (c) shows the form of forming the adhesive layer 11. When the shielding layer is a conductive adhesive layer, it is not necessary to provide an adhesive layer separately from the shielding layer.

FIG. 3 (d) shows a state where the transfer film 40 has been peeled from the electromagnetic wave shielding film 10. In addition, the up-down direction of the electromagnetic wave shielding film 10 is inverted from the direction shown in FIG. 3 (c) and displayed.
The transfer film is peeled after the electromagnetic wave shielding film is adhered to a printed circuit board or the like. By peeling the transfer film, the surface of the insulating layer 13 is exposed. The maximum valley depth Sv of the exposed insulating layer surface was 3.0 μm or more.
By the above steps, the electromagnetic wave shielding film of the present invention can be prepared.

(Shield printed circuit board)
Next, a shielded printed wiring board of the present invention provided with the electromagnetic wave shielding film of the present invention will be described.
4 is a cross-sectional view schematically showing an example of a cross-section of a shielded printed circuit board of the present invention.
The shielded printed circuit board 50 shown in FIG. 4 includes: a printed circuit board 20; an electromagnetic wave shielding film 10 in which a shielding layer 12 is disposed on the printed circuit board 20 side and laminated on the printed circuit board 20; The reinforcing plate 80 is provided on the insulating layer 13 of the electromagnetic wave shielding film 10.

In addition, in this specification, "arranging a shielding layer on the printed circuit board side" means that the shielding layer is arranged on the printed circuit board side when viewing the positions of the shielding layer and the insulating layer. It does not mean that the shield is in contact with the printed circuit board. In addition, as shown in FIG. 4, when the electromagnetic wave shielding film 10 has a three-layer structure, even if the shielding layer 12 is a central layer, the shielding layer 12 is disposed closer to the printed circuit board 20 side than the insulating layer 13. The shielding layer is placed on the side of the printed circuit board.
This requirement means that the insulating layer is provided at a position where it can be contacted with the member to be adhered, and not the insulating layer is provided at a position in contact with the printed circuit board.

The printed circuit board 20 includes a base film 21, a printed circuit 22 formed on the base film 21, and a cover layer 23 formed to cover the printed circuit 22.

The materials of the base film 21 and the cover layer 23 constituting the printed circuit board 20 are not particularly limited, and are preferably composed of engineering plastics. Examples of such engineering plastics include polyethylene terephthalate, polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimide, imide, and polyetherimide. , Polyphenylene sulfide and other resins.
Also, among these engineering plastics, when flame retardance is required, a polyphenylene sulfide film is preferred; when heat resistance is required, a polyimide film is preferred. In addition, the thickness of the base film 21 is preferably 10 to 40 μm. The thickness of the cover layer 23 is preferably 10 to 30 μm.

The printed circuit 22 constituting the printed circuit board 20 is not particularly limited, and can be formed by performing an etching process or the like on a conductive material.
Examples of the conductive material include copper, nickel, silver, and gold.

A reinforcing plate 80 is provided on the insulating layer 13 of the electromagnetic wave shielding film 10 as a member to be adhered.
The reinforcing plate 80 as a member to be bonded is bonded to the insulating layer 13 of the electromagnetic wave shielding film 10 through an adhesive layer 82 provided on the surface of the member to be bonded.
FIG. 4 shows an example in which the reinforcing plate 80 is used as the adhered member. The adhered member is not particularly limited as long as it is a member that can pass through the adhesive layer provided on the surface of the adhered member and adhere to the insulating layer of the electromagnetic wave shielding film.

The reinforcing plate as a bonded member is a member for improving the mechanical strength of the shield printed circuit board. As the reinforcing plate, a metal reinforcing plate made of a metal material should be used.
Examples of such a metal material include stainless steel.
The thickness of the metal reinforcing plate should be 0.05mm ~ 1mm.
If the thickness of the metal reinforcing plate is less than 0.05 mm, the strength is insufficient, and the effect of improving the mechanical strength cannot be fully exerted.
If the thickness of the metal reinforcing plate is greater than 1 mm, it is difficult to dispose the shielded printed circuit board in an electronic instrument due to the large volume.

The adhered member is adhered to the insulating layer of the electromagnetic wave shielding film through an adhesive layer provided on the surface of the adhered member.
As the adhesive layer provided on the surface of the member to be adhered, an adhesive layer having the same structure as the adhesive layer described so far as the constituent element of the electromagnetic wave shielding film can be used.
The adhesive layer provided on the surface of the adhered member may be a conductive adhesive layer or an insulating adhesive layer.

In the electromagnetic wave shielding film of the present invention used in the shielded printed circuit board of the present invention, the maximum valley depth Sv of the surface of the insulating layer of the bonded member is 3.0 μm or more. Therefore, the adhesive layer and the electromagnetic wave provided on the surface of the bonded member are The shielding film can exhibit high adhesion strength between the insulating layers.
In addition, through the adhesive layer provided on the surface of the adhered member, the adhered member can be adhered to the insulating layer with high strength.

The adhered member used in the shielded printed circuit board of the present invention may also use a ground member.
5 is a cross-sectional view schematically showing an example of a cross section of another shielded printed circuit board of the present invention.
The shielded printed wiring board shown in FIG. 5 includes a ground member 30 as a member to be bonded.
The ground member 30 includes a connection portion 31 and a metal foil 33.
The connecting portion 31 is a portion for connecting the shielding layer and the external ground, and the connecting portion 31 penetrates the insulating layer 13 of the electromagnetic wave shielding film 10 and contacts the shielding layer 12 of the electromagnetic wave shielding film 10. The connection portion 31 is a conductive material, and the shielding layer 12 and the metal foil 33 can be electrically connected through the connection portion 31.
The metal foil 33 may be connected to an external ground.
The connecting portion 31 is preferably made of a conductive filler.

The ground member 30 is bonded to the insulating layer 31 through an adhesive layer 32 provided on the surface of the member to be bonded.
The adhesive layer 32 provided on the surface of the member to be adhered also has a function of bonding between the connection portion 31 and the metal foil 33. Since the connection portion 31 and the metal foil 33 must be electrically connected, it is preferably a conductive adhesive layer.

The conductive filler used as the connecting portion preferably contains particles selected from the group consisting of copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, gold-coated nickel powder, and resin-coated metal powder. Make up at least one of the groups.
These particles are excellent in electrical conductivity.

The average particle diameter of the conductive filler used as the connection portion is preferably 1 to 200 μm.
If the average particle diameter of the conductive filler is less than 1 μm, it is difficult to penetrate the insulating layer of the electromagnetic wave shielding film because the conductive filler is small.
If the average particle diameter of the conductive filler is larger than 200 μm, a strong pressure is required to penetrate the insulating layer of the electromagnetic wave shielding film because the conductive filler becomes large.

The metal foil used for the grounding member is not particularly limited as long as it is made of a conductive metal. For example, the metal foil is preferably selected from the group consisting of copper, aluminum, silver, gold, nickel, chromium, titanium, zinc, and stainless steel. At least one of the groups.

In the electromagnetic wave shielding film of the present invention used in the shielded printed circuit board of the present invention, the maximum valley depth Sv of the surface of the insulating layer of the adhered member is 3.0 μm or more. The film has high adhesion strength between the insulating layers.
In addition, the ground member can be adhered to the insulating layer with high strength through the adhesive layer provided on the surface of the ground member.

(Manufacturing method of shielded printed circuit board)
Next, a method for manufacturing a shielded printed circuit board according to the present invention will be described.
In the method for manufacturing a shielded printed circuit board of the present invention, the electromagnetic wave shielding film of the present invention is used.

FIG. 6 is a step diagram schematically showing an example of a method for manufacturing a shielded printed circuit board according to the present invention.
FIG. 6 shows an example in which the reinforcing plate 80 is used as a member to be bonded.

First, the electromagnetic wave shielding film 10 is laminated on the printed circuit board 20 such that the shielding layer 12 is disposed on the printed circuit board 20 side to prepare a shielded printed circuit board 50 ′.
When a thermosetting resin is used as the adhesive layer of the electromagnetic wave shielding film, the thermosetting resin is hardened by heating after lamination, thereby bonding the electromagnetic wave shielding film and the printed circuit board.
The surface of the insulating layer 13 of the shield printed circuit board 50 '(the surface indicated by the reference symbol A in FIG. 6) is exposed, and the maximum valley depth Sv of the surface is 3.0 μm or more.

In addition, a reinforcing plate 80 having an adhesive layer 82 on the surface is prepared.
The arithmetic mean thickness Sa of the surface of the adhesive layer 82 provided on the surface of the reinforcing plate 80 facing the insulating layer 13 (the surface indicated by reference symbol B in FIG. 6) is preferably 0.05 to 2.0 μm.
By setting the surface provided on the adhesive layer side of the adhered member to a specific surface state, the bonding strength between the insulating layer of the electromagnetic wave shielding film and the adhered member can be further improved.
Next, the arithmetic average roughness of the surface of the agent layer can be measured using analysis software (LMeye7) provided by a surface shape measuring machine such as OPTELICS HYBRID manufactured by Lasertec Corporation.
The treatment for setting the surface of the adhesive layer provided on the member to be adhered to a specific surface state includes, for example, a roughening treatment and a smoothing treatment. When the adhesive layer provided on the adhered member is a conductive adhesive layer and contains conductive particles, the surface of the adhesive layer provided on the adhered member can be adjusted by adjusting the average particle diameter of the conductive particles. status.

As shown in FIG. 6, the adhesive layer 82 provided on the surface of the reinforcing plate 80 as a member to be adhered is disposed to face the insulating layer 13, and then adhered by a method such as pressure bonding, thereby making it possible to produce electromagnetic waves. A shielding printed circuit board is provided on the insulating layer 13 of the shielding film 10 as a reinforcing plate 80 as a member to be bonded.

Examples The following shows examples of the present invention in more detail, but the present invention is not limited to these examples.

(Transfer film)
The transfer films used in the examples and comparative examples were prepared.
The following transfer films 1 to 6 are all polyethylene terephthalate films. The maximum valley depth Sv on the surface and the interface development area ratio Sdr are controlled as follows.
The transfer film 1 is a sandblasted film.
The transfer films 2 to 4 are kneaded films in which silicon dioxide fine particles having an average particle diameter of 1 to 3 μm have been kneaded in a polyethylene terephthalate resin.
The transfer film 5 is a kneaded film in which silicon dioxide fine particles having an average particle diameter of 5 to 10 μm have been kneaded in a polyethylene terephthalate resin.
The transfer film 6 is a film which is not surface-treated.
Transfer film 1: Sv6.8μm, Sdr26.9%
Transfer film 2: Sv3.1 μm, Sdr 18.5%
Transfer film 3: Sv2.5μm, Sdr15.7%
Transfer film 4: Sv6.0μm, Sdr44.6%
Transfer film 5: Sv7.8μm, Sdr120.5%
Transfer film 6: Sv0.5μm, Sdr0.1%

(Example 1)
An epoxy resin was applied to the transfer film 1 and heated at 100 ° C. for 2 minutes using an electric oven to prepare an insulating layer having a thickness of 5 μm.
Then, a 2 μm copper layer was formed on the insulating layer by electroless plating. This copper layer becomes the shielding layer.

Next, 100.0 parts of amidine modified epoxy resin, 49.6 parts of silver-clad copper powder (average particle diameter D50: 15 μm), and 49.6 parts of an organic phosphorus-based flame retardant were mixed to prepare a composition for an adhesive layer.
The composition for the adhesive layer was coated on a copper layer and heated at 100 ° C. for 2 minutes using an electric oven to produce an adhesive layer having a thickness of 15 μm.
Through the above steps, an electromagnetic wave shielding film is produced on the transfer film.

The transfer film was peeled from the electromagnetic wave shielding film to expose the surface of the insulating layer, and the maximum valley depth Sv and the interface expansion area ratio Sdr of the surface of the insulating layer were measured using a confocal microscope (manufactured by Lasertec, OPTELICS HYBRID) At this time, the maximum valley depth Sv was 4.2 μm, and the interface development area ratio Sdr was 14.7%.

(Examples 2 to 5, Comparative Example 1)
An electromagnetic wave shielding film was produced in the same manner as in Example 1 except that any one of the transfer films 2 to 6 was used instead of the transfer film 1.
Table 1 summarizes the transfer film used in each Example and Comparative Example, and the maximum valley depth Sv of the surface of the insulating layer and the interface development area ratio Sdr.

(Next, the measurement of strength)
In order to investigate the relationship between the surface properties of the insulating layer of the shielding film and the bonding strength of the bonded member, an adhesive film (AAP-25TP manufactured by Arisawa Manufacturing Co., Ltd.) was used as a model of the bonded member, and the adhesive film was stuck to the shielding film. The insulation layer was used to measure the adhesion strength.
Specifically, the pressure-sensitive adhesive layer and the polyimide film (thickness: 25 μm) of the shielding films produced in each of the Examples and Comparative Examples were heated and pressed under conditions of 170 ° C., 3 minutes, and 2.0 MPa using a press. It was then heated at 150 ° C. for 1 hour to be bonded together.
Next, the pressure-sensitive adhesive film and a glass epoxy resin (FR-4) having a thickness of 1 mm were heated and pressed at a temperature of 120 ° C., 5 seconds, and 0.5 MPa to make them adhere to each other.
Then, the pressure-sensitive adhesive film was bonded to the insulating layer of the shielding film under conditions of 170 ° C., 30 minutes, and 3 MPa using a press to obtain a laminated body for subsequent strength measurement.
Next, the laminated body was sandwiched between the insulating layer and the adhesive film of the shielding film by a peeling interface, and was stretched at a tensile speed by a tensile tester (made by Shimadzu Corporation, trade name AGS-X50S) at room temperature. The peeling was performed at 50 mm / min and a peeling angle of 90 °, and the maximum value of the peeling strength at the time of breaking was measured. Moreover, when the peeling strength was 3.0 N / cm or more, it was evaluated that it was excellent in adhesiveness.
In this adhesive film, an acrylic resin is used as an adhesive layer, and the arithmetic average roughness Sa of the surface facing the insulating layer is in the range of 0.06 to 0.22 μm.
Table 1 shows the minimum value (N / cm) of the adhesion strength measurement of each example and comparative example.

[Table 1]

As shown in Table 1, it can be seen that, as for the surface of the insulating layer as the bonding surface, if the maximum valley depth Sv, which is an index showing the state of the surface, is 3.0 μm or more, it can exhibit high performance when the bonded member is bonded. Then intensity.

10, 110‧‧‧ electromagnetic shielding film

11‧‧‧ Adhesive layer (adhesive layer which is different from the shielding layer in the electromagnetic wave shielding film)

12, 112‧‧‧Shield

13, 113‧‧‧ Insulation

20‧‧‧printed circuit board

21‧‧‧ basement membrane

22‧‧‧Printed Circuit

23‧‧‧ Overlay

30‧‧‧ Grounding member (adhered member)

31‧‧‧Connection Department

32, 82‧‧‧ Adhesive layer (adhesive layer provided on the surface of the adhered member)

33‧‧‧metal foil

40‧‧‧ transfer film

50, 50’‧‧‧shielded printed circuit board

80‧‧‧ Reinforcing plate (adhered member)

A‧‧‧ surface of insulation layer

B‧‧‧ The surface of the adhesive layer on the surface of the adhered member facing the insulating layer

C‧‧‧ surface of transfer film

FIG. 1 is a cross-sectional view schematically showing an example of a cross-section of an electromagnetic wave shielding film of the present invention.

2 is a cross-sectional view schematically showing an example of a cross-section of an electromagnetic wave shielding film according to another embodiment of the present invention.

FIG. 3 (a), FIG. 3 (b), FIG. 3 (c), and FIG. 3 (d) are step diagrams, which schematically show an example of a method for manufacturing the electromagnetic wave shielding film of the present invention.

4 is a cross-sectional view schematically showing an example of a cross-section of a shielded printed circuit board of the present invention.

5 is a cross-sectional view schematically showing an example of a cross section of another shielded printed circuit board of the present invention.

FIG. 6 is a step diagram schematically showing an example of a method for manufacturing a shielded printed circuit board according to the present invention.

Claims (7)

An electromagnetic wave shielding film includes a shielding layer and an insulating layer laminated on the shielding layer, and is characterized in that: The maximum valley depth Sv on the surface of the insulating layer is 3.0 μm or more. For example, the electromagnetic wave shielding film of claim 1, wherein the interface expansion area ratio Sdr of the surface of the foregoing insulating layer is 5.0% or more. A shielded printed circuit board, comprising: A printed circuit board; If the electromagnetic wave shielding film of claim 1 or 2, the shielding layer is arranged on the printed circuit board side and laminated on the printed circuit board; and A bonded member provided on the insulating layer of the aforementioned electromagnetic wave shielding film; In addition, the adhered member is adhered to the insulating layer of the electromagnetic wave shielding film through an adhesive layer provided on a surface of the adhered member. The shielded printed circuit board according to claim 3, wherein the aforementioned bonded member is a reinforcing board. The shielded printed circuit board according to claim 3, wherein the adhered member is a grounding member having a connecting portion for connecting the shielding layer to the external ground, and the connecting portion of the grounding member penetrates the electromagnetic wave shield. The insulating layer of the film is in contact with the shielding layer of the electromagnetic wave shielding film. A method for manufacturing a shielded printed circuit board is characterized by having the following steps: For the surface of the insulating layer of the electromagnetic wave shielding film according to claim 1 or 2, the adhered member provided with an adhesive layer on the surface is bonded to the insulating layer in the aforementioned adhesive layer. The method for manufacturing a shielded printed circuit board according to claim 6, wherein the arithmetic mean thickness Sa of the surface of the adhesive layer provided on the adhered member facing the insulating layer is 0.05 to 2.0 μm.