TWI720356B - Electromagnetic wave shield film and shield printed circuit board - Google Patents

Abstract

The subject of the present invention is to provide an electromagnetic wave shielding film. When a grounding member is arranged on the electromagnetic wave shielding film, the connecting portion of the grounding member can easily contact the shielding layer of the electromagnetic wave shielding film. The electromagnetic wave shielding film of the present invention is characterized by being composed of an adhesive layer, a shielding layer laminated on the adhesive layer, and an insulating layer laminated on the shielding layer, and the elastic modulus of the adhesive layer is 80-1500 MPa.

Description

Electromagnetic wave shielding film and shielding printed wiring board

Invention field The present invention relates to electromagnetic wave shielding films and shielding printed wiring boards.

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 often used in order to assemble circuits into complex mechanisms. Furthermore, using its excellent flexibility, it will also be used in the connection between the movable part and the control part such as a printing head. In these electronic devices, electromagnetic wave shielding measures must be provided. As for the flexible printed wiring boards used in the devices, flexible printed wiring boards that have been electromagnetically shielded have also begun to be used (hereinafter also referred to as "shielding" Printed wiring board").

A general shielding printed wiring board is usually composed of a base film and an electromagnetic wave shielding film. The base film is formed by sequentially placing a printed circuit and an insulating film on the base film. The electromagnetic wave shielding film is composed of an adhesive layer and an electromagnetic wave shielding film. The shielding layer of the agent layer and the insulating layer laminated on the above-mentioned adhesive layer are composed of, and are laminated on the above-mentioned base film in such a way that the above-mentioned adhesive layer and the above-mentioned base film are in contact with each other. The printed circuit contains a grounding circuit, and the grounding circuit is electrically connected to the frame of the electronic instrument in order to be grounded. As mentioned above, in the base film of the shielded printed wiring board, an insulating film is provided on the printed circuit including the ground circuit. In addition, the base film is covered by a shielding film, and the shielding film has an insulating layer. Therefore, in order to electrically connect the grounding circuit to the frame of the electronic device, a hole must be made in part of the insulating film and the shielding film in advance. This will become a major factor hindering the degree of freedom in designing printed circuits.

Patent Document 1 discloses a shielding film which is coated on one side of a separation film to form a cover film, and a shielding layer composed of a metal thin film layer and an adhesive layer is provided on the surface of the cover film, and has a grounding member. The grounding member is formed to have a protrusion (connecting portion) that is pressed onto the cover film and penetrates the cover film to connect to the shielding layer on one end side, and the other end is exposed to be connected to a grounding portion nearby. When the shielding film described in Patent Document 1 is produced, the grounding member is pressed to the cover film so that the protrusion (connection portion) of the grounding member penetrates the cover film. Therefore, the grounding member can be arranged at any position of the shielding film. If such a grounding member is used to manufacture a shielded printed wiring board, the grounding circuit can be electrically connected to the frame of the electronic device at any position.

Prior art literature Patent literature Patent Document 1: Japanese Patent No. 4201548

Summary of the invention The problem to be solved by the invention When the shielded printed wiring board described in Patent Document 1 is manufactured, the ground member is pressed to the cover film in such a way that the protrusion (connection portion) of the ground member penetrates the cover film. At this time, there may be cases where the protrusion (connecting portion) of the grounding member cannot penetrate the cover film sufficiently and the protrusion (connecting portion) of the grounding member cannot sufficiently contact the shielding layer of the shielding film. When the protrusion (connection part) of the grounding member cannot fully contact the shielding layer of the shielding film, the resistance value will increase.

The present invention is made in view of the above-mentioned problems. The object of the present invention is to provide an electromagnetic wave shielding film in which when a grounding member is arranged on the electromagnetic wave shielding film, the connecting portion of the grounding member can easily contact the shielding layer of the electromagnetic wave shielding film.

Means to solve the problem The inventors of the present invention found that when the grounding member is pressed onto the electromagnetic wave shielding film in such a way that the connecting portion of the grounding member penetrates the insulating layer of the electromagnetic wave shielding film, the elastic modulus of the adhesive layer of the electromagnetic wave shielding film affects the electromagnetic wave shielding The ease of penetration of the insulating layer of the film completes the present invention. That is, the electromagnetic wave shielding film of the present invention is characterized by being composed of an adhesive layer, a shielding layer, and an insulating layer, the shielding layer is laminated on the adhesive layer; the insulating layer is laminated on the shielding layer, and the elasticity of the adhesive layer The modulus is 80~1500MPa.

If the elastic modulus of the adhesive layer is 80 to 1500 MPa, the adhesive layer constitutes a moderate hardness. Therefore, when the grounding member is pressed onto the electromagnetic wave shielding film, the connection part of the grounding member easily penetrates the insulating layer of the electromagnetic wave shielding film. If the elastic modulus of the adhesive layer is less than 80 MPa, the adhesive layer is too soft. When the grounding member is pressed to the electromagnetic wave shielding film, the adhesive layer of the electromagnetic wave shielding film will absorb pressure. Therefore, the connection part of the grounding member cannot easily penetrate the insulating layer of the electromagnetic wave shielding film. If the elastic modulus of the adhesive layer is greater than 1500 MPa, the adhesive layer is too hard, and the overall flexibility of the electromagnetic wave shielding film will be lost.

In the electromagnetic wave shielding film of the present invention, the fracture elongation of the adhesive layer is preferably 310% or less. If the elongation at break of the adhesive layer is greater than 310%, the adhesive layer becomes too soft. When the grounding member is pressed to the electromagnetic wave shielding film, the adhesive layer of the electromagnetic wave shielding film easily absorbs pressure. Therefore, the connection part of the grounding member cannot easily penetrate the insulating layer of the electromagnetic wave shielding film.

In the electromagnetic wave shielding film of the present invention, the adhesive layer may be a conductive adhesive layer. Usually, the electronic circuit of the printed wiring board is also provided with a grounding circuit. When the adhesive layer of the electromagnetic wave shielding film of the present invention is a conductive adhesive layer, by disposing the electromagnetic wave shielding film on the printed wiring board so that the adhesive layer of the electromagnetic wave shielding film contacts the ground circuit, the electrical connection. Furthermore, in the electromagnetic wave shielding film of the present invention, a grounding member is arranged. Furthermore, the grounding member will be connected to the external ground. Therefore, by making the adhesive layer of the electromagnetic wave shielding film of the present invention into a conductive adhesive layer, the grounding circuit of the printed wiring board can be electrically connected to the external ground through the electromagnetic wave shielding film and the grounding member of the present invention.

The shielding printed wiring board of the present invention is characterized by comprising: a base film including a base film and a printed circuit formed on the base film; the electromagnetic wave shielding film of the present invention laminated on the base film; and a grounding member, It has a connecting portion for connecting the shielding layer of the electromagnetic wave shielding film to an external ground; the electromagnetic wave shielding film is laminated on the base film in such a way that the adhesive layer of the electromagnetic wave shielding film contacts the base film, and the ground The connecting portion of the member penetrates the insulating layer of the electromagnetic wave shielding film and contacts the shielding layer of the electromagnetic wave shielding film.

The electromagnetic wave shielding film of the present invention described above is used in the shielding printed wiring board of the present invention. Therefore, the connecting portion of the grounding member penetrates the insulating layer of the electromagnetic wave shielding film and fully contacts the shielding layer of the electromagnetic wave shielding film. Therefore, in the shielded printed wiring board of the present invention, the connection portion of the ground member and the shielding layer of the electromagnetic wave shielding film are sufficiently electrically connected.

In the shielded printed wiring board of the present invention, the grounding member may be composed of a metal foil and a conductive filler, and the conductive filler is a connection part fixed to the metal foil by an adhesive resin. Moreover, the said ground member may be comprised by metal foil and a conductive protrusion, and this conductive protrusion may be a connection part formed in the said metal foil. In addition, the above-mentioned grounding member may be formed by bending a metal foil, and the convex and folding part of the metal foil is the above-mentioned connecting part. Although the grounding member has such a structure, when the grounding member is arranged on the electromagnetic wave shielding film, the connecting portion of the grounding member can still penetrate the insulating layer of the electromagnetic wave shielding film. Therefore, in the shielded printed wiring board of the present invention, the connection portion of the grounding member is in sufficient contact with the shielding layer of the electromagnetic wave shielding film.

Invention effect In the electromagnetic wave shielding film of the present invention, the elastic modulus of the adhesive layer is 80-1500 MPa. If the elastic modulus of the adhesive layer is 80~1500MPa, the adhesive layer will have moderate hardness. Therefore, when the grounding member is pressed onto the electromagnetic wave shielding film, the connection part of the grounding member easily penetrates the insulating layer of the electromagnetic wave shielding film .

The form used to implement the invention Hereinafter, the electromagnetic wave shielding film of the present invention will be specifically explained. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within a range that does not change the gist of the present invention.

Fig. 1 schematically shows a cross-sectional view of an example of the electromagnetic wave shielding film of the present invention. The electromagnetic wave shielding film 10 shown in FIG. 1 is composed of an adhesive layer 11, a shielding layer 12 laminated on the adhesive layer 11, and an insulating layer 13 laminated on the shielding layer 12. In addition, the elastic modulus of the adhesive layer 11 is 80 to 1500 MPa.

In addition, the electromagnetic wave shielding film 10 is used to manufacture shielded printed wiring boards. Here, a shielded printed wiring board using the electromagnetic wave shielding film 10 will be described.

Fig. 2 is a cross-sectional view schematically showing an example of a shielded printed wiring board using the electromagnetic wave shielding film of the present invention. As shown in FIG. 2, the shielding printed wiring board 1 includes: a base film 20 composed of 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; electromagnetic waves The shielding film 10 is laminated on the base film 20; and the ground member 30 is used to connect the shielding layer 12 of the electromagnetic wave shielding film 10 to the external ground GND.

In the shielding printed wiring board 1, the electromagnetic wave shielding film 10 is laminated on the base film 20 such that the adhesive layer 11 of the electromagnetic wave shielding film 10 contacts the base film 20.

The ground member 30 is composed of a metal foil 31 and a conductive filler 33, and the conductive filler 33 is fixed to the metal foil 31 by an adhesive resin 32.

In addition, the conductive filler 33 of the ground member 30 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. Therefore, in the shielded printed wiring board 1, the conductive filler 33 of the grounding member 30 and the shielding layer 12 of the electromagnetic wave shielding film 10 are electrically connected. That is, the conductive filler 33 has a function as a connection portion connecting the electromagnetic wave shielding film 10 and the ground member 30.

When manufacturing such a shielded printed wiring board 1, after laminating the electromagnetic wave shielding film 10 on the base film 20, the grounding member 30 is pressed so that the conductive filler 33 of the grounding member 30 penetrates the insulating layer 13 of the electromagnetic wave shielding film 10 To the electromagnetic wave shielding film 10.

As mentioned above, the elastic modulus of the adhesive layer 11 of the electromagnetic wave shielding film 10 is 80-1500 MPa. Therefore, the adhesive layer 11 of the electromagnetic wave shielding film 10 has a moderate hardness. Therefore, when the grounding member 30 is pressed to the electromagnetic wave shielding film 10, the conductive filler 33 of the grounding member 30 easily penetrates the insulating layer 13 of the electromagnetic wave shielding film 10. In addition, if the elastic modulus of the adhesive layer of the electromagnetic wave shielding film is less than 80 MPa, the adhesive layer is too soft. When the grounding member is pressed onto the electromagnetic wave shielding film, the adhesive layer of the electromagnetic wave shielding film absorbs pressure. Therefore, the connection part of the grounding member cannot easily penetrate the insulating layer of the electromagnetic wave shielding film. If the elastic modulus of the adhesive layer is greater than 1500 MPa, the adhesive layer is too hard, and the overall flexibility of the electromagnetic wave shielding film will be lost.

In addition, in the electromagnetic wave shielding film 10, the elastic modulus of the adhesive layer 11 is preferably 60-1100 MPa, and more preferably 100-700 MPa.

In the electromagnetic wave shielding film 10, the fracture elongation of the adhesive layer 11 is preferably 310% or less, and is more preferably 10~310%, and more preferably 50~310%. If the elongation at break of the adhesive layer is greater than 310%, the adhesive layer becomes too soft. When the grounding member is pressed onto the electromagnetic wave shielding film, the adhesive layer of the electromagnetic wave shielding film easily absorbs pressure. Therefore, the connection part of the grounding member cannot easily penetrate the insulating layer of the electromagnetic wave shielding film.

In the electromagnetic wave shielding film 10, the adhesive layer 11 may be composed of a thermosetting resin, or may be composed of a thermoplastic resin. Examples of thermosetting resins include phenol resins, epoxy resins, urethane resins, melamine resins, polyamide resins, and alkyd resins. In addition, examples of the thermoplastic resin include styrene resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, imine resins, and acrylic resins. In addition, the epoxy resin is more preferably an amide modified epoxy resin. These resins are suitable as resins constituting the adhesive layer.

The thickness of the adhesive layer 11 of the electromagnetic wave shielding film 10 is not particularly limited, and is 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, and therefore, it is difficult to obtain sufficient adhesive performance. Also, it will become easily damaged. If the thickness of the adhesive layer is greater than 50 μm, the entire electromagnetic wave shielding film becomes thicker, and the flexibility is likely to be lost.

In the electromagnetic wave shielding film 10, the adhesive layer 11 may also be a conductive adhesive layer. Generally, the electronic circuit of the printed wiring board is also provided with a grounding circuit. When the adhesive layer 11 of the electromagnetic wave shielding film 10 is a conductive adhesive layer, the electromagnetic wave shielding film 10 can be arranged on a printed wiring board so that the adhesive layer 11 of the electromagnetic wave shielding film 10 is in contact with the ground circuit. Isoelectric connection. Furthermore, as described above, the ground member 30 is arranged on the electromagnetic wave shielding film 10. Furthermore, the ground member 30 is connected to the external ground GND. Therefore, by setting the adhesive layer 11 of the electromagnetic wave shielding film 10 as a conductive adhesive layer, the ground circuit of the printed wiring board can be electrically connected to the external ground GND through the electromagnetic wave shielding film 10 and the ground member 30.

When the adhesive layer 11 of the electromagnetic wave shielding film 10 is a conductive adhesive layer, the adhesive layer 11 may be composed of conductive particles and an adhesive resin composition.

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

When the conductive particles are metal particles, there are no special restrictions on the metal particles. They 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 an economic point of view, copper powder or silver-clad copper powder that can be obtained at a low price is preferable.

The average particle diameter of the conductive particles is not particularly limited, and it is preferably 0.5-15.0μm. 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, fibrous, and the like.

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

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

Moreover, when the adhesive layer 11 is a conductive adhesive layer, it is preferable to have anisotropic conductivity. If the adhesive layer 11 has anisotropic conductivity, the transmission characteristics of the high-frequency signal transmitted by the signal circuit of the printed wiring board will be improved compared to the case of the isotropic conductivity.

In addition, the adhesive layer 11 of the electromagnetic wave shielding film 10 may contain flame retardants, flame retardant aids, hardening accelerators, adhesiveness imparting agents, antioxidants, pigments, dyes, plasticizers, ultraviolet absorbers, and anti-corrosion agents as needed. Foaming agent, leveling agent, filler, viscosity regulator, etc. By adding these substances to the adhesive layer 11 of the electromagnetic wave shielding film 10, the modulus of elasticity and the elongation at break can also be adjusted.

Examples of flame retardants include: organophosphorus flame retardants, nitrogen compound flame retardants, bromine compound flame retardants, antimony flame retardants, metal hydroxides, chlorine compound flame retardants, boron compound flame retardants Burning agent, etc.

Examples of the flame-retardant auxiliary agent include nitrogen-based flame-retardant auxiliary agents.

In order to make the elastic modulus of the conductive adhesive layer within a predetermined range, various compounds can also be used. For such a compound, a filler having an elastic modulus higher than that of the adhesive resin composition can be used. As examples of the filler, nitrogen-based compounds, silicon dioxide-based compounds, organic phosphorus-based compounds, etc. can be used, and nitrogen-based compounds are preferably used. In addition, this compound may have other functions such as a flame retardant or a flame retardant auxiliary in addition to the function as a filler. If a nitrogen-based compound with the function as a filler and the function as a flame retardant or flame retardant auxiliary agent is used, the imparting of flame retardancy and the adjustment of the elastic modulus can be considered. As such a nitrogen-based compound, for example, a known nitrogen compound-based flame retardant can be used.

The compound having a function as a filler is preferably in the form of particles. At this time, the elastic modulus of the particles should be 50~2000MPa, and the average particle size should be 0.5~30μm. The blending amount of the compound having the function as a filler is preferably 10 to 300 parts by mass relative to 100 parts by mass of the adhesive resin composition.

The shielding layer 12 of the electromagnetic wave shielding film 10 can be made of any material as long as it has electromagnetic wave shielding properties, for example, it can be made of a metal layer.

The shielding layer 12 may include a layer composed of materials such as gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, and zinc, and preferably includes a copper layer. From the viewpoint of conductivity and economy, copper is a suitable material for the shielding layer 12. In addition, the shielding layer 12 may also include a layer composed of an alloy of the above-mentioned metals.

The thickness of the shielding layer 12 is preferably 0.01-10 μm. If the thickness of the shielding layer is less than 0.01 μm, it is not easy to obtain a sufficient shielding effect. If the thickness of the shielding layer is greater than 10μm, it will become difficult to bend.

The insulating layer 13 of the electromagnetic wave shielding film 10 is not particularly limited as long as it has sufficient insulating properties and can protect the adhesive layer 11 and the shielding layer 12. For example, it is preferably composed of a thermoplastic resin composition, a thermosetting resin composition, and active energy. Consisting of linear curable composition. The above-mentioned thermoplastic resin composition is not particularly limited, and examples thereof include: styrene resin composition, vinyl acetate resin composition, polyester resin composition, polyethylene resin composition, polypropylene resin composition, Imide resin composition, acrylic resin composition, etc.

The above-mentioned thermosetting resin composition is not particularly limited, and examples include: phenol resin composition, epoxy resin composition, urethane resin composition, melamine resin composition, and alkyd resin composition Wait.

The active energy ray curable composition is not particularly limited. For example, a polymerizable compound having at least two (meth)acryloxy groups in the molecule can be exemplified.

The insulating layer 13 may be composed of one single material, or may be composed of two or more materials.

The insulating layer 13 may optionally contain hardening accelerators, adhesiveness imparting agents, antioxidants, pigments, dyes, plasticizers, ultraviolet absorbers, defoamers, leveling agents, fillers, flame retardants, Viscosity regulator, anti-caking agent, etc.

The thickness of the insulating layer 13 is not particularly limited, and can be appropriately set as needed, and is ideally 1-15 μm, and more preferably 3-10 μm. If the thickness of the insulating layer is less than 1 μm, it will be too thin, so it is not easy to fully protect the adhesive layer and the shielding layer. If the thickness of the insulating layer is greater than 15 μm, it will be too thick. Therefore, the conductive filler of the grounding member cannot easily penetrate the insulating layer of the electromagnetic wave shielding film.

In the electromagnetic wave shielding film 10, an undercoat layer may also be formed between the shielding layer 12 and the insulating layer 13. The material of the undercoat layer can include, for example: urethane resin, acrylic resin, core-shell composite resin with urethane resin as the shell and acrylic resin as the core, epoxy resin, amide resin, and amide resin. Amine resins, melamine resins, phenol resins, urea-formaldehyde resins, blocked isocyanates obtained by reacting blocking agents such as phenol with polyisocyanates, polyvinyl alcohol, polyvinyl hydropyrrolidone, etc.

The shielding printed wiring board using the electromagnetic wave shielding film of the present invention is also the shielding printed wiring board of the present invention. That is, the above-mentioned shield printed wiring board 1 is the shield printed wiring board of the present invention.

The base film 20 constituting the shield printed wiring board 1 will be described.

The materials of the base film 21 and the cover layer 23 constituting the base film 20 are not particularly limited, and they are preferably made of engineering plastics. Examples of such engineering plastics include polyethylene terephthalate, polypropylene, cross-linked polyethylene, polyester, polybenzimidazole, polyimide, polyimide, and polyetherimide. , Polyphenylene sulfide and other resins. In addition, among these engineering plastics, when flame retardancy is required, polyphenylene sulfide film is preferable, and when heat resistance is required, polyimide film is preferable. In addition, the thickness of the base film 21 is preferably 10-40 μm. In addition, the thickness of the covering layer 23 is preferably 10 to 30 μm.

The printed circuit 22 constituting the base film 20 is not particularly limited, and can be formed by etching a conductive material or the like. Examples of conductive materials include copper, nickel, silver, and gold.

Next, the ground member 30 constituting the shielded printed wiring board 1 will be described.

The conductive filler 33 of the grounding member 30 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. The electrical conductivity of these particles is excellent.

In the grounding member 30, the average particle size of the conductive filler 33 is preferably 1 to 200 μm. If the average particle size of the conductive filler is less than 1 μm, the conductive filler is small, and therefore, it is difficult to penetrate the insulating layer of the electromagnetic wave shielding film. If the average particle size of the conductive filler is greater than 200 μm, the conductive filler becomes larger, and therefore, a strong pressure is required in order to penetrate the insulating layer of the electromagnetic wave shielding film.

In the grounding member 30, the material of the adhesive resin 32 is not particularly limited. A styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, and polypropylene can be used. Thermoplastic resin composition such as resin composition, amide resin composition, amide resin composition, acrylic resin composition; or phenol resin composition, epoxy resin composition, urethane Thermosetting resin compositions such as resin compositions, melamine resin compositions, alkyd resin compositions, and the like. The material of the adhesive resin may be one of these alone, or a combination of two or more.

In the grounding member 30, the metal foil 31 is not particularly limited as long as it is made of conductive metal. For example, it is preferable to include those made of copper, aluminum, silver, gold, nickel, chromium, titanium, zinc, and stainless steel. At least one in the group. These materials have excellent electrical conductivity.

In addition, in the shielded printed wiring board of the present invention, the ground member may have the following structure. Fig. 3 is a cross-sectional view schematically showing another example of the shielded printed wiring board of the present invention. Fig. 4 is a cross-sectional view schematically showing another example of the shielded printed wiring board of the present invention.

The shield printed wiring board 101 shown in FIG. 3 has the same structure as the shield printed wiring board 1 described above except that the grounding member 30 is replaced by the grounding member 130.

In the shielded printed wiring board 101 shown in FIG. 3, the ground member 130 is composed of a metal foil 131 and a conductive protrusion 134, and the conductive protrusion 134 is formed on the metal foil 131. In the shielding printed wiring board 101, the conductive protrusion 134 of the ground member 130 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. Therefore, in the shielding printed wiring board 101, the conductive protrusion 134 of the ground member 130 is electrically connected to the shielding layer 12 of the electromagnetic wave shielding film 10. That is, the conductive protrusion 134 has a function as a connection portion connecting the electromagnetic wave shielding film 10 and the ground member 130.

In the ground member 130, the conductive protrusion 134 may be integrated with the metal foil 131, or may be bonded to the metal foil 131 by adhesive resin or the like.

In the grounding member 130, the metal foil 131 is not particularly limited as long as it is made of conductive metal. For example, it is preferable to include those selected from copper, aluminum, silver, gold, nickel, chromium, titanium, zinc, and stainless steel. At least one in the group. These materials have excellent electrical conductivity.

In the ground member 130, the material of the conductive protrusion 134 is not particularly limited. For example, it is preferable to include at least one selected from the group consisting of copper, aluminum, silver, gold, nickel, chromium, titanium, zinc, and stainless steel. . In addition, the metal foil 131 and the conductive protrusion 134 are preferably made of the same material.

In the grounding member 130, the conductive protrusion 134 may be columnar, for example, a column, an elliptic column, a triangular column, a quadrangular column, a pentagonal column, a hexagonal column, an octagonal column, etc. If the conductive protrusion 134 has a columnar shape, it will easily penetrate the insulating layer 13 of the electromagnetic wave shielding film 10.

In the grounding member 130, the area of the bottom surface of the conductive protrusion 134 is preferably 1.0 to 1.0×10 ⁶ μm ² . If the area of the bottom surface of the conductive protrusion is less than 1.0 μm ² , the strength of the conductive protrusion is weakened, and the conductive protrusion is easily broken. If the area of the bottom surface of the conductive protrusion is greater than 1.0×10 ⁶ μm ² , the conductive protrusion is too thick, so it is difficult to penetrate the insulating layer of the electromagnetic wave shielding film.

In the grounding member 130, the distance between the conductive protrusions 134 is preferably 1 to 1000 μm. It is technically difficult to manufacture a grounding member with a distance between conductive protrusions of less than 1 μm. If the distance between the conductive protrusions is greater than 1000 μm, the density will decrease, and the total contact area of the conductive protrusions of the grounding member and the shielding layer of the electromagnetic wave shielding film will decrease. Therefore, the resistance becomes easy to increase.

In the grounding member 130, the height of the conductive protrusion 134 is not particularly limited as long as it can penetrate the insulating layer 13 of the electromagnetic wave shielding film 10, and it is preferably 3-20 μm.

The shield printed wiring board 201 shown in FIG. 4 has the same structure as the shield printed wiring board 1 described above except that the grounding member 30 is replaced by the grounding member 230.

In the shielded printed wiring board 201 shown in FIG. 4, the grounding member 230 is formed by bending a metal foil 231. In addition, a convex fold 235 is formed on the metal foil 231. In the shielding printed wiring board 201, the protruding portion 235 of the grounding member 230 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. Therefore, in the shielding printed wiring board 201, the protruding portion 235 of the ground member 230 and the shielding layer 12 of the electromagnetic wave shielding film 10 are electrically connected. That is, the protruding portion 235 has a function as a connecting portion that connects the electromagnetic wave shielding film 10 and the ground member 230.

In the grounding member 230, the metal foil 231 is not particularly limited as long as it is made of conductive metal. For example, it is preferable to include those selected from copper, aluminum, silver, gold, nickel, chromium, titanium, zinc, and stainless steel. At least one in the group. These materials have excellent electrical conductivity.

In the grounding member 230, the height of the protruding portion 235 is not particularly limited as long as it can penetrate the insulating layer 13 of the electromagnetic wave shielding film 10, and it is preferably 3-20 μm.

Example The following shows more specific embodiments of the present invention, but the present invention is not limited to these embodiments. In addition, in the description of the following examples, "parts" means parts by mass.

(Example 1) First, a polyethylene terephthalate film that has been peeled off on one side is prepared as a first peeling film. Next, epoxy resin was applied to the peeling treatment surface of the first peeling film and heated at 100°C for 2 minutes in an electric oven to produce an insulating layer with a thickness of 5 μm. Then, a 2μm copper layer is formed on the insulating layer by electroless plating. This copper layer constitutes a shielding layer.

Next, 100.0 parts of amido-modified epoxy resin, _{49.6 parts of dendritic silver-coated copper powder (average particle size D 50} : 13 μm), and 56.2 parts of organic phosphorus flame retardant were mixed to produce an adhesive layer composition. Next, a polyethylene terephthalate film that has been peeled off on one side is prepared as a second peeling film. In addition, the adhesive layer composition was applied to the release-treated surface of the second release film, and heated at 100° C. for 2 minutes in an electric oven to produce an adhesive layer with a thickness of 15 μm.

Next, the insulating layer formed on the first release film and the adhesive layer formed on the second release film were bonded together to produce the electromagnetic wave shielding film of Example 1.

(Examples 2 to 4) and (Comparative Example 1) Except that the composition for the adhesive layer was changed to the composition shown in Table 1, the electromagnetic wave shielding films of Examples 2 to 4 and Comparative Example 1 were produced in the same manner as in Example 1. In addition, the numerical value of the composition of the adhesive layer in Table 1 represents parts by mass. In addition, the melamine cyanurate contained in the composition for the adhesive layer has a function as a flame retardant auxiliary agent and a filler for adjusting the elastic modulus.

[Table 1]

(Measurement of elastic modulus and breaking elongation of adhesive layer) The elastic modulus (MPa) and breaking elongation (%) of the adhesive layer of the electromagnetic wave shielding film of each example and each comparative example were measured by the following methods. The adhesive layer composition for forming the adhesive layer of the electromagnetic wave shielding film was applied to the release film, and the release film was peeled off to produce the test adhesive layer. A dumbbell-shaped test piece (100 mm×10 mm, 20 mm between the marking lines) was prepared from the test adhesive layer, and a tensile tester (AGS-X50S, manufactured by Shimadzu Corporation) was used to measure the elastic modulus and elongation at break. The measurement conditions are as follows: tensile speed: 50 mm/min, load cell: 50N. The modulus of elasticity is calculated from the gradient of the stress (2~3MPa) and the elongation at break. The results are shown in Table 1.

(Manufacture of shielded printed wiring boards) Using the electromagnetic wave shielding film of each Example and each comparative example, the shielding printed wiring board was manufactured by the following method.

A base film is prepared. The base film is formed by sequentially arranging a printed circuit containing a grounding circuit and a cover layer on the base film. In the base film, the base film is made of polyimide resin (length 5mm, width 10mm, thickness: 12μm), the ground circuit and printed circuit are made of copper, and the cover layer is made of polyimide resin (thickness: 12μm) . In addition, a hole for exposing a part of the printed circuit is formed in the cover layer. In addition, a grounding member composed of a metal foil and a conductive filler is prepared, and the conductive filler is fixed to the metal foil by an adhesive resin. In the ground member, the metal foil is copper foil (thickness: 6 μm), the adhesive resin is 6 μm, and the conductive filler is silver-coated copper particles (average particle size: 10-15 μm).

Next, the electromagnetic wave shielding film is arranged on the base film in such a way that the adhesive layer of each electromagnetic wave shielding film is connected to the base film. Then, under the conditions of 170° C., 3 MPa, pre-pressure for 60 seconds, and main pressure for 180 seconds, each electromagnetic wave shielding film was thermocompression-bonded to the base film. Then, it was dried at 150°C for 1 hour.

Next, two grounding members were arranged on each electromagnetic wave shielding film at an interval of 1 cm. Then, the grounding member was temporarily fixed to the electromagnetic wave shielding film under conditions of 170°C, 3MPa, 7 seconds of preload, and 43 seconds of main pressure, and then thermocompression bonding was performed under conditions of 170°C, 3MPa, and 15 minutes. Thereby, the conductive filler of the grounding member penetrates the insulating layer of the electromagnetic wave shielding film and contacts the shielding layer of the electromagnetic wave shielding film. Then, it was dried at 150°C for 1 hour to produce a shielded printed wiring board.

According to this method, four shielding printed wiring boards were produced for each electromagnetic wave shielding film, and the resistance value between the two grounding members of each shielding printed wiring board was measured. Table 1 shows the average value of the obtained resistance values. When the resistance value between the two grounding members is low, it means that the conductive filler of the grounding member is in sufficient contact with the shielding layer of the electromagnetic wave shielding film. Conversely, when the resistance value between the two grounding members is high, it means that the conductive filler of the grounding member and the shielding layer of the electromagnetic wave shielding film are not sufficiently contacted.

As shown in Table 1, in the shielding printed wiring board using the electromagnetic wave shielding film of each example in which the elastic modulus of the adhesive layer is 80 to 1500 MPa, the resistance value between the grounding members is low. That is, the conductive filler of the grounding member and the shielding layer of the electromagnetic wave shielding film are in sufficient contact.

1, 101, 201‧‧‧Shielding printed wiring board 10‧‧‧Electromagnetic wave shielding film 11‧‧‧Adhesive layer 12‧‧‧Shielding layer 13‧‧‧Insulation layer 20‧‧‧Matrix membrane 21‧‧‧Basement membrane 22‧‧‧Printed Circuit 23‧‧‧Cover 30, 130, 230‧‧‧Grounding member 31, 131, 231‧‧‧Metal foil 32‧‧‧Adhesive resin 33‧‧‧Conductive filler 134‧‧‧Conductive protrusion 235‧‧‧Protrusion GND‧‧‧External ground

Fig. 1 is a cross-sectional view schematically showing an example of the electromagnetic wave shielding film of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of a shielded printed wiring board using the electromagnetic wave shielding film of the present invention. Fig. 3 is a cross-sectional view schematically showing another example of the shielded printed wiring board of the present invention. Fig. 4 is a cross-sectional view schematically showing another example of the shielded printed wiring board of the present invention.

10‧‧‧Electromagnetic wave shielding film

11‧‧‧Adhesive layer

12‧‧‧Shielding layer

13‧‧‧Insulation layer

Claims (6)

An electromagnetic wave shielding film characterized by being composed of the following layers: an adhesive layer; a shielding layer laminated on the aforementioned adhesive layer; and an insulating layer laminated on the aforementioned shielding layer; the elastic modulus of the aforementioned adhesive layer is 80~1500Mpa, and the aforementioned adhesive layer is a conductive adhesive layer. The electromagnetic wave shielding film of claim 1, wherein the breaking elongation of the aforementioned adhesive layer is 310% or less. A shielding printed wiring board, comprising: a base film including a base film and a printed circuit formed on the base film; the electromagnetic wave shielding film of claim 1 or 2, which is laminated on the base film; and grounding A member having a connecting portion for connecting the shielding layer of the electromagnetic wave shielding film to an external ground; the electromagnetic wave shielding film is laminated on the base film in such a way that the adhesive layer of the electromagnetic wave shielding film contacts the base film, The connection part of the grounding member penetrates the insulating layer of the electromagnetic wave shielding film and contacts the shielding layer of the electromagnetic wave shielding film. The shielded printed wiring board of claim 3, wherein the grounding member is composed of a metal foil and a conductive filler, and the conductive filler is the connection portion fixed to the metal foil by an adhesive resin. The shielded printed wiring board of claim 3, wherein the grounding member is composed of a metal foil and a conductive protrusion, and the conductive protrusion is formed on the connecting portion of the metal foil. The shielded printed wiring board according to claim 3, wherein the grounding member is formed by bending a metal foil, and the protruding portion of the metal foil is the connecting portion.

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