KR20190117494A - Electromagnetic shielding film, shielded printed wiring boards and electronic equipment - Google Patents

Abstract

An object of this invention is to provide the electromagnetic wave shielding film which is hard to fall shielding characteristic at the time of manufacturing a shielding printed wiring board, and has sufficient bending resistance.
The electromagnetic wave shielding film of this invention is an electromagnetic wave shielding film which consists of a conductive adhesive layer, the shielding layer laminated | stacked on the said conductive adhesive layer, and the insulating layer laminated | stacked on the said shielding layer, A some opening part is formed in the said shielding layer, And the opening area of the opening is 70 to 71000 µm ² , and the opening ratio of the opening is 0.05 to 3.6%.

Description

Electromagnetic shielding film, shielded printed wiring boards and electronic equipment

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

Conventionally, for example, attaching an electromagnetic wave shielding film to printed wiring boards, such as a flexible printed wiring board (FPC), and shielding the electromagnetic wave from the exterior is performed.

The electromagnetic wave shielding film usually has a structure in which a conductive adhesive layer, a shielding layer made of a metal thin film, or the like, and an insulating layer are laminated in this order. By heat-pressing the said electromagnetic wave shielding film in the state superimposed on a printed wiring board, an electromagnetic wave shielding film is adhere | attached to a printed wiring board with an adhesive bond layer, and a shielding printed wiring board is produced. After the adhesion, the components are mounted on the printed wiring board by solder reflow. Moreover, the printed wiring board has the structure by which the print pattern on the base film was coat | covered with the insulating film.

When manufacturing a shielding printed wiring board, when a shielding printed wiring board is heated by a hot press or solder reflow, gas will generate | occur | produce from the electrically conductive adhesive bond layer of an electromagnetic wave shielding film, the insulating film of a printed wiring board, etc. Moreover, when the base film of a printed wiring board is formed from resin with high hygroscopicity, such as polyimide, water vapor may generate | occur | produce from a base film by heating. Since these volatile components resulting from a conductive adhesive layer, an insulating film, or a base film cannot pass through a shielding layer, they are accumulated between a shielding layer and a conductive adhesive layer. Therefore, when rapid heating is performed in the solder reflow step, the interlayer adhesion between the shielding layer and the conductive adhesive layer may be destroyed by the volatile components accumulated between the shielding layer and the conductive adhesive layer, and the shielding characteristics may be degraded.

In order to solve such a problem, patent document 1 describes the electromagnetic wave shielding film which provided the some opening part in the shielding layer (metal thin film), and improved air permeability.

If a plurality of openings are formed in the shielding layer, even if a volatile component is generated, the volatile component can pass through the shielding layer through the opening. Therefore, it is possible to prevent the volatile components from accumulating between the shielding layer and the conductive adhesive layer, and to prevent the deterioration of the shielding property due to the breakage of interlayer adhesion.

International Publication No. 2014/192494

However, since the opening part is formed in the shielding layer of the electromagnetic wave shielding film of patent document 1, the strength of a shielding layer is weak.

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

That is, the flexible printed wiring board is repeatedly bent at the time of use. The electromagnetic wave shielding film used for such a flexible printed wiring board, and the shielding layer which comprises this electromagnetic wave shielding film are also bent repeatedly.

As mentioned above, since the shielding layer of the electromagnetic wave shielding film of patent document 1 is weak in strength, when it is bent repeatedly, there existed a problem that a shielding layer was easy to be destroyed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shielding film which is hardly deteriorated in shielding properties when producing a shielded printed wiring board and has sufficient bending resistance.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, as a result of earnestly examining, the present inventor controls the opening area of the opening part formed in the shielding layer of an electromagnetic wave shielding film, and the opening ratio of an opening part, and is shielded manufactured using the said electromagnetic wave shielding film. It was found that the shielding property can be prevented from being lowered in the printed wiring board, and the bending resistance of the shielded printed wiring board is further improved, and the present invention has been completed.

That is, the electromagnetic wave shielding film of this invention is an electromagnetic wave shielding film which consists of a conductive adhesive layer, the shielding layer laminated | stacked on the said conductive adhesive layer, and the insulating layer laminated | stacked on the said shielding layer, The said shielding layer has a some opening part. It is formed, The opening area of the said opening part is 70-71000 micrometer <^2> , and The opening ratio of the said opening part is characterized by being 0.05 to 3.6%.

In the electromagnetic wave shielding film of this invention, the some opening part is formed in the shielding layer. Therefore, even when a volatile component is generated between the shielding layer and the conductive adhesive layer in the heat press step, the solder reflow step, or the like when the shielding printed wiring board is manufactured using the electromagnetic shielding film of the present invention, the volatile component is the shielding layer. It can pass through the opening of.

Therefore, a volatile component becomes difficult to accumulate between a shielding layer and a conductive adhesive layer. As a result, breakage of interlayer adhesion can be prevented.

In the electromagnetic wave shielding film of this invention, the opening area of the said opening part is 70-71000 micrometer <^2> , and the opening ratio of the said opening part is 0.05 to 3.6%.

If the opening area and the opening ratio of the opening formed in the shielding layer are within the above ranges, the bend resistance is sufficient, and it is possible to prevent the volatile component from accumulating between the shielding layer and the conductive adhesive layer.

If the opening area of the opening is less than 70 µm ² , the opening is too narrow, and the volatile components are less likely to pass through the shielding layer. As a result, a volatile component accumulates easily between a shielding layer and a conductive adhesive layer. Therefore, when manufacturing a shielding printed wiring board using the said electromagnetic wave shielding film, the adhesiveness between layers of a shielding layer and a conductive adhesive layer becomes easy to be destroyed. As a result, the shielding property is lowered.

When the opening area of the opening portion exceeds 71000 µm ² , the opening portion is too wide, the shielding layer is weak, and the bending resistance is lowered.

When the opening ratio of the opening portion is less than 0.05%, the ratio of the opening portion is too small, and the volatile component becomes difficult to pass through the shielding layer. As a result, a volatile component accumulates easily between a shielding layer and a conductive adhesive layer.

When the opening ratio of the opening portion exceeds 3.6%, the ratio of the opening portion is too large, the shielding layer is weakened, and the bending resistance decreases.

In addition, in this specification, an "opening ratio" means the total opening area of several opening part with respect to the area of the whole main surface of a shielding layer.

In the electromagnetic wave shielding film of this invention, it is preferable that the opening pitch of the said opening part is 10-10000 micrometers.

When the opening pitch of the opening is less than 10 µm, the proportion of the opening increases in the entire shielding layer. As a result, the shielding layer becomes weak and the bending resistance falls.

When the opening pitch of the opening exceeds 10000 µm, the proportion of the opening decreases as a whole of the shielding layer. As a result, the volatile component hardly passes through the shielding layer, and the volatile component easily accumulates between the shielding layer and the conductive adhesive layer.

In addition, in this specification, the "opening pitch of an opening part" means the distance between the centers of the opening parts which adjoin nearest.

In the electromagnetic wave shielding film of this invention, it is preferable that the thickness of the said shielding layer is 0.5 micrometer or more.

If the thickness of a shielding layer is less than 0.5 micrometer, since a shielding layer is too thin, a shielding characteristic will become low.

In the electromagnetic wave shielding film of this invention, it is preferable that the said shielding layer contains a copper layer.

Copper is a suitable material for a shielding layer from a viewpoint of electroconductivity and economy.

In the electromagnetic wave shielding film of this invention, it is preferable that the said shielding layer further contains a silver layer, the said silver layer is arrange | positioned at the said insulating layer side, and the said copper layer is arrange | positioned at the said conductive adhesive bond layer side.

The electromagnetic wave shielding film of such a structure can be easily manufactured by apply | coating silver paste so that an opening part may be formed in an insulating layer, and making it a silver layer, and plating a silver layer with copper.

It is preferable that the electromagnetic wave shielding film of this invention is for flexible printed wiring boards.

As mentioned above, the electromagnetic wave shielding film of this invention hardly collects a volatile component between a shielding layer and a conductive adhesive layer when manufacturing a shielding printed wiring board. Moreover, the electromagnetic wave shielding film of this invention has sufficient bending resistance. Therefore, even if the electromagnetic wave shielding film of this invention is used for a flexible printed wiring board and bent repeatedly, it is hard to be damaged.

Therefore, the electromagnetic wave shielding film of this invention can be used suitably as an electromagnetic wave shielding film for flexible printed wiring boards.

The shielding printed wiring board of this invention is a shielding printed wiring board which has a base member with a printed circuit, the printed wiring board which has an insulation film provided on the said base member so that the said printed circuit may be covered, and the electromagnetic wave shielding film provided on the said printed wiring board. As an electromagnetic wave shielding film, the electromagnetic wave shielding film of the present invention may be used.

Moreover, in the shielded printed wiring board of this invention, it is preferable that the said printed wiring board is a flexible printed wiring board.

The shielding printed wiring board of this invention contains the electromagnetic wave shielding film of this invention which has sufficient bending resistance. Therefore, the shielded printed wiring board of the present invention also has sufficient bending resistance.

The electronic device of the present invention is characterized in that the shielded printed wiring board of the present invention is assembled in a bent state.

As mentioned above, the shielding printed wiring board of this invention has sufficient bending resistance. Therefore, even if assembled to the electronic device in a bent state, it is difficult to be damaged. Therefore, the electronic device of this invention can narrow the space for arrange | positioning a shielded printed wiring board.

Therefore, the electronic device of the present invention can be made thin.

In the electromagnetic wave shielding film of this invention, the some opening part is formed in a shielding layer, the opening area of the said opening part is 70-71000 micrometer <^2> , and the opening ratio of the said opening part is 0.05 to 3.6%.

When the characteristic of the opening part formed in the shielding layer is the said range, bending resistance is enough, and when a shielding printed wiring board is manufactured using the electromagnetic wave shielding film of this invention, a volatile component accumulates between a shielding layer and a conductive adhesive layer. It can prevent.

1: is sectional drawing which shows an example of the electromagnetic wave shielding film of this invention typically.
FIG.2 (a) and FIG.2 (b) is a schematic diagram which shows typically the case where a shielding printed wiring board is manufactured using the electromagnetic wave shielding film in which the opening part is not formed in the shielding layer.
3 (a) to 3 (c) are plan views schematically showing an example of the arrangement pattern of the openings in the shielding layer constituting the electromagnetic wave shielding film of the present invention.
It is sectional drawing which shows typically an example of the electromagnetic wave shielding film of this invention in which a shielding layer consists of a copper layer and a silver layer.
FIG.5 (a)-FIG. 5 (c) are process drawing which shows an example of the manufacturing method of the electromagnetic wave shielding film of this invention typically in order.
It is process drawing which shows typically an example of the insulating layer preparation process in the manufacturing method of the electromagnetic wave shielding film of this invention.
FIG. 7: is a process figure which shows typically an example of the silver paste printing process in the manufacturing method of the electromagnetic wave shielding film of this invention.
8 is a flowchart schematically showing an example of a silver paste printing step in the method for producing an electromagnetic wave shielding film of the present invention.
It is process drawing which shows typically an example of the silver paste printing process in the manufacturing method of the electromagnetic wave shielding film of this invention.
FIG.10 (a) and FIG.10 (b) are process drawing which shows typically an example of the copper plating process in the manufacturing method of the electromagnetic wave shielding film of this invention.
FIG.11 (a) and FIG.11 (b) are process drawing which shows typically an example of the conductive adhesive bond layer formation process in the manufacturing method of the electromagnetic wave shielding film of this invention.
It is a schematic diagram which shows typically the structure of the system used by a KEC method.

EMBODIMENT OF THE INVENTION Hereinafter, the electromagnetic wave shielding film of this invention is demonstrated concretely. However, this invention is not limited to the following embodiment, It can change suitably and apply in the range which does not change the summary of this invention.

1: is sectional drawing which shows an example of the electromagnetic wave shielding film of this invention typically.

As shown in FIG. 1, the electromagnetic shielding film 10 includes a conductive adhesive layer 20, a shielding layer 30 stacked on the conductive adhesive layer 20, and an insulating layer 40 stacked on the shielding layer 30. )

In addition, a plurality of openings 50 are formed in the shielding layer 30.

(Conductive adhesive layer)

In the electromagnetic wave shielding film 10, the conductive adhesive layer 20 may be comprised with what kind of material, as long as it has electroconductivity and can function as an adhesive agent.

For example, the conductive adhesive layer 20 may be composed of conductive particles and an adhesive resin composition.

Although it does not specifically limit as electroconductive particle, Metal microparticles | fine-particles, a carbon nanotube, carbon fiber, a metal fiber, etc. may be sufficient.

In the case where the conductive particles are metal fine particles, the metal fine particles are not particularly limited, but silver powder, copper powder, nickel powder, solder powder, aluminum powder and copper powder may be coated with silver coated copper powder, polymer fine particles or glass beads. Fine particles coated with a metal may be used.

In these, it is preferable from a viewpoint of economics that it is a low cost copper powder or silver coating copper powder.

Although the average particle diameter of electroconductive particle is not specifically limited, It is preferable that it is 0.5-15.0 micrometers. If the average particle diameter of electroconductive particle is 0.5 micrometer or more, the electroconductivity of a conductive adhesive layer will become favorable. If the average particle diameter of electroconductive particle is 15.0 micrometers or less, a conductive adhesive layer can be made thin.

Although the shape of electroconductive particle is not specifically limited, It can select suitably from a spherical form, a flat form, a flaky form, a dendrite form, a rod form, a fibrous form, etc ..

Although it does not specifically limit as a material of an adhesive resin composition, A styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an amide resin composition, Thermosetting resin compositions, such as thermoplastic resin compositions, such as an acrylic resin composition, a phenolic resin composition, an epoxy resin composition, a urethane resin composition, a melamine resin composition, an alkyd resin composition, etc. can be used.

The material of adhesive resin composition may be single 1 type, or 2 or more types of combinations may be sufficient as them.

As necessary, the conductive adhesive layer 20 may include a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity regulator, and the like.

Although the compounding quantity of the electroconductive particle in the electroconductive adhesive bond layer 20 is not specifically limited, It is preferable that it is 15-80 mass%, and it is more preferable that it is 15-60 mass%.

If it is the said range, the adhesiveness to a printed wiring board of a conductive adhesive layer will improve.

Although the thickness of the electroconductive adhesive bond layer 20 is not specifically limited, Although it can set suitably as needed, it is preferable that it is 0.5-20.0 micrometers.

If the thickness of a conductive adhesive layer is less than 0.5 micrometer, it will become difficult to obtain favorable electroconductivity. When the thickness of a conductive adhesive layer exceeds 20.0 micrometers, the thickness of the whole electromagnetic wave shielding film will become thick and it will become difficult to handle.

In addition, it is preferable that the conductive adhesive layer 20 has anisotropic conductivity.

When the conductive adhesive layer 20 has anisotropic conductivity, the transmission characteristic of the high frequency signal transmitted by the signal circuit of a printed wiring board improves compared with the case of having isotropic conductivity.

(Insulation layer)

In the electromagnetic wave shielding film 10, although the insulating layer 40 has sufficient insulation and can protect the conductive adhesive layer 20 and the shielding layer 30, it will not specifically limit, For example, a thermoplastic resin composition and a thermosetting property It is preferable that it is comprised from a resin composition, an active energy ray curable composition, etc.

Although it does not specifically limit as said thermoplastic resin composition, A styrene resin composition, a vinyl acetate resin composition, a polyester resin composition, a polyethylene resin composition, a polypropylene resin composition, an imide resin composition, an acrylic resin composition etc. are mentioned. have.

Although it does not specifically limit as said thermosetting resin composition, A phenol resin composition, an epoxy resin composition, a urethane resin composition, a melamine resin composition, an alkyd resin composition etc. are mentioned.

Although it does not specifically limit as said active energy ray curable composition, For example, the polymeric compound etc. which have at least two (meth) acryloyloxy group in a molecule | numerator are mentioned.

The insulating layer 40 may be comprised with 1 type of independent material, and may be comprised with 2 or more types of material.

The insulation layer 40 may contain a hardening accelerator, a tackifier, antioxidant, a pigment, dye, a plasticizer, a ultraviolet absorber, an antifoamer, a leveling agent, a filler, a flame retardant, a viscosity modifier, an antiblocking agent, etc. as needed.

Although the thickness of the insulating layer 40 is not specifically limited, Although it can set suitably as needed, it is preferable that it is 1-15 micrometers, and it is more preferable that it is 3-10 micrometers.

If the thickness of the insulating layer 40 is less than 1 micrometer, since it is too thin, it will become difficult to fully protect the conductive adhesive layer 20 and the shielding layer 30. FIG.

When the thickness of the insulating layer 40 exceeds 15 micrometers, since it is too thick, the electromagnetic wave shielding film 10 will become difficult to bend and the insulating layer 40 itself will become easy to be damaged. Therefore, it becomes difficult to apply to a member for which bending resistance is required.

(Shielding layer)

Before explaining the shielding layer of the electromagnetic wave shielding film of this invention, the case where a shielding printed wiring board is manufactured using the electromagnetic wave shielding film in which the opening part is not formed in a shielding layer is demonstrated with reference to drawings.

FIG.2 (a) and FIG.2 (b) is a schematic diagram which shows typically the case where a shielding printed wiring board is manufactured using the electromagnetic wave shielding film in which the opening part is not formed in the shielding layer.

As shown in Fig. 2A, when manufacturing the shielded printed wiring board, the shielded printed wiring board on which the electromagnetic shielding film 510 is disposed is heated by a hot press or solder reflow.

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

When rapid heating is performed in such a state, as shown in Fig. 2B, the volatile component 560 accumulated between the shielding layer 530 and the conductive adhesive layer 520, and the shielding layer 530 and Interlayer adhesion of the conductive adhesive layer 520 may be broken.

However, in the electromagnetic wave shielding film 10, the some opening part 50 is formed in the shielding layer 30. FIG.

Therefore, when manufacturing a shielding printed wiring board using the electromagnetic wave shielding film 10, even if a volatile component generate | occur | produced between the shielding layer 30 and the conductive adhesive layer 20 by heating, a volatile component is a shielding layer 30 It may pass through the opening 50 of.

Therefore, the volatile component becomes difficult to accumulate between the shielding layer 30 and the conductive adhesive layer 20. As a result, breakage of interlayer adhesion can be prevented.

In the electromagnetic shielding film 10, the opening area of the opening portion 50 is 70 to 71000 µm ² , and the opening ratio of the opening portion 50 is 0.05 to 3.6%.

The opening area of the opening 50 it is more preferred that the 70~32000㎛ ² is preferred, and, and more preferably 70~10000㎛ ² 80~8000㎛ ^2.

Moreover, it is preferable that the opening ratio of the opening part 50 is 0.1 to 3.6%.

If the opening area and the opening ratio of the opening portion 50 formed in the shielding layer 30 are within the above ranges, the bending resistance is sufficient, and the volatile component between the shielding layer 30 and the conductive adhesive layer 20 can be prevented. Can be.

When the opening area of the opening of the shielding layer is less than 70 µm ² , the opening is too narrow, and the volatile components hardly pass through the shielding layer. As a result, a volatile component accumulates easily between a shielding layer and a conductive adhesive layer.

When the opening area of the opening of the shielding layer exceeds 71000 µm ² , the opening is too wide, the shielding layer is weak, and the bending resistance is lowered.

When the opening ratio of the opening of the shielding layer is less than 0.05%, the ratio of the opening is too small, and the volatile components hardly pass through the shielding layer. As a result, a volatile component accumulates easily between a shielding layer and a conductive adhesive layer.

When the opening ratio of the opening of the shielding layer exceeds 3.6%, the ratio of the opening is too large, the shielding layer is weakened, and the bend resistance is lowered.

In the electromagnetic wave shielding film 10, the shape of the opening part 50 is not specifically limited, A round shape, an ellipse, a racetrack shape, a triangle, a rectangle, a pentagon, a hexagon, an octagon, a star, etc. may be sufficient.

In these, it is preferable that it is circular from the ease of opening part 50 formation.

In addition, the shape of the some opening part 50 may be single 1 type, and multiple types may be combined.

In the electromagnetic wave shielding film 10, it is preferable that the opening pitch of the opening part 50 is 10-10000 micrometers, It is more preferable that it is 25-2000 micrometers, It is further more preferable that it is 250-2000 micrometers.

When the opening pitch of the opening is less than 10 µm, the proportion of the opening increases in the entire shielding layer. As a result, the shielding layer becomes weak and the bending resistance falls.

When the opening pitch of the opening exceeds 10000 µm, the proportion of the opening decreases as a whole of the shielding layer. As a result, the volatile component becomes difficult to pass through the shielding layer, and the volatile component easily accumulates between the shielding layer and the conductive adhesive layer.

In the electromagnetic wave shielding film 10, although the arrangement pattern of the opening part 50 is not specifically limited, For example, the arrangement pattern shown below may be sufficient.

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

As shown in FIG. 3A, in the arrangement pattern of the openings 50, the arrangement pattern in which the center of each of the openings 50 is located at the vertex of the equilateral triangle in a plane in which the equilateral triangles are vertically and continuously arranged. It may be.

In addition, as shown in Fig. 3B, the arrangement pattern of the openings 50 is an arrangement in which the center of the openings 50 is located at the vertices of the square in a plane in which the squares are continuously arranged vertically and horizontally. It may be a pattern.

In addition, as shown in Fig. 3C, the arrangement pattern of the openings 50 is arranged in such a manner that the center of the openings 50 is located at the vertices of the regular hexagon in a plane in which the regular hexagons are arranged vertically and horizontally. It may be a pattern.

In the electromagnetic wave shielding film 10, it is preferable that the thickness of the shielding layer 30 is 0.5 micrometer or more, and it is more preferable that it is 1.0 micrometer or more. Moreover, it is preferable that the thickness of the shielding layer 30 is 10 micrometers or less.

If the thickness of a shielding layer is less than 0.5 micrometer, since a shielding layer is too thin, a shielding characteristic will become low.

Moreover, when the thickness of the shielding layer 30 is 1.0 micrometer or more, the transmission characteristic will become favorable in the signal transmission system which transmits the high frequency signal of 0.01-10 GHz.

And when an opening part is not formed in a shielding layer, when a shielding layer becomes thick, when an shielding printed wiring board is manufactured, breakage of the interlayer adhesion between a shielding layer and a conductive adhesive layer will arise easily. In particular, when the thickness of the shielding layer 30 exceeds 1.0 µm, breakage of interlayer adhesion occurs remarkably. However, in the electromagnetic wave shielding film 10, since the opening part 50 is formed in the shielding layer 30, interlayer adhesion between the shielding layer 30 and the conductive adhesive layer 20 can be prevented from being destroyed.

It is preferable that the electromagnetic wave shielding film of this invention is used for the signal transmission system which transmits the signal whose frequency is 0.01-10 GHz.

In the electromagnetic wave shielding film of this invention, as long as a shielding layer has electromagnetic wave shielding property, what kind of material may be sufficient and it may be made from a metal layer, for example.

The shielding layer may include a layer made of a material such as gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, or zinc, and preferably includes a copper layer.

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

The shielding layer may include a layer made of an alloy of the metal.

The shielding layer may be formed by stacking a plurality of metal layers.

In particular, the shielding layer preferably includes a copper layer and a silver layer.

The case where a shielding layer contains a copper layer and a silver layer is demonstrated with reference to drawings.

It is sectional drawing which shows typically an example of the electromagnetic wave shielding film of this invention in which a shielding layer consists of a copper layer and a silver layer.

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

In addition, the shielding layer 130 is composed of a copper layer 132 and a silver layer 131, the silver layer 131 is disposed on the insulating layer 140 side, the copper layer 132 is a conductive adhesive layer 120 It is arranged on the side.

The electromagnetic wave shielding film 110 of such a structure can be easily manufactured by apply | coating silver paste so that an opening part may be formed in the insulating layer 140, and making it a silver layer, and plating copper on a silver layer.

(Other composition)

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

As the material of the anchor coat layer, a core-shell composite resin having an urethane resin, an acrylic resin, a urethane resin as a shell and an acrylic resin as a core, an epoxy resin, an imide resin, an amide resin, a melamine resin, a phenol resin, a urea formaldehyde resin, Block isocyanate, polyvinyl alcohol, polyvinylpyrrolidone etc. which were obtained by making blocking agent, such as a phenol, react with polyisocyanate are mentioned.

In addition, in the electromagnetic wave shielding film of this invention, the support film may be included in the insulating layer side, and the peelable film may be included in the conductive adhesive layer side. If the electromagnetic wave shielding film contains a support film or a peelable film, the electromagnetic wave of this invention in the operation | movement at the time of manufacture of the transportation of the electromagnetic wave shielding film of this invention, the shielding printed wiring board using the electromagnetic wave shielding film of this invention, etc. The shielding film becomes easy to handle.

Moreover, when arrange | positioning the electromagnetic wave shielding film of this invention to a shielding printed wiring board etc., such a support film and a peelable film will peel.

The electromagnetic wave shielding film of the present invention may be used for any purpose as long as it is intended to block electromagnetic waves.

In particular, it is preferable to use the electromagnetic wave shielding film of this invention for a printed wiring board, especially a flexible printed wiring board.

As mentioned above, the electromagnetic wave shielding film of this invention hardly collects a volatile component between a shielding layer and a conductive adhesive layer when manufacturing a shielding printed wiring board. Moreover, the electromagnetic wave shielding film of this invention has sufficient bending resistance. Therefore, even if the electromagnetic wave shielding film of this invention is used for a flexible printed wiring board and bent repeatedly, it is hard to be damaged.

Therefore, the electromagnetic wave shielding film of this invention can be used suitably as an electromagnetic wave shielding film for flexible printed wiring boards.

Thus, the shielding printed wiring board which has the electromagnetic wave shielding film of this invention is a shielding printed wiring board of this invention.

That is, the shielding printed wiring board of this invention contains the base member with a printed circuit, the printed wiring board which has an insulation film provided on the said base member so that the said printed circuit might be covered, and the electromagnetic wave shielding film provided on the said printed wiring board. As a shielding printed wiring board, the said electromagnetic wave shielding film is an electromagnetic wave shielding film of the said invention, It is characterized by the above-mentioned.

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

The shielding printed wiring board of this invention contains the electromagnetic wave shielding film of this invention which has sufficient bending resistance. Therefore, the shielded printed wiring board of the present invention also has sufficient bending resistance.

The shielded printed wiring board of the present invention is used by being assembled to an electronic device.

In particular, the electronic device assembled with the shielded printed wiring board of the said invention is bent is the electronic device of this invention.

As mentioned above, the shielding printed wiring board of this invention has sufficient bending resistance. Therefore, even if assembled to the electronic device in a bent state, it is difficult to be damaged. Therefore, the electronic device of this invention can narrow the space for arrange | positioning a shielded printed wiring board.

Therefore, the electronic device of the present invention can be made thin.

(Method for producing electromagnetic shielding film)

Next, the manufacturing method of the electromagnetic wave shielding film of this invention is demonstrated. And the electromagnetic wave shielding film of this invention is not limited to what was manufactured by the method shown below.

First, an example of the manufacturing method of the electromagnetic wave shielding film 10 which is an example of the electromagnetic wave shielding film of this invention is demonstrated.

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

These processes are explained in full detail below using drawing.

FIG.5 (a)-(c) are process drawing which shows an example of the manufacturing method of the electromagnetic wave shielding film of this invention typically in order.

(1) shielding layer forming process

First, as shown to Fig.5 (a), the sheet | seat 35 which has electromagnetic wave shielding property is prepared, and in the sheet | seat 35 so that opening area may be 70-71000 micrometer <^2> and opening ratio may be 0.05-3.6%. The opening part 50 is formed and the shielding layer 30 is produced.

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

In addition, when the sheet | seat 35 consists of etching material, such as copper, even if it forms the resist of the pattern like the opening part 50 is formed in the surface of the sheet | seat 35, even if the opening part 50 is formed by etching, do.

In addition, you may print the electrically conductive paste and the paste which functions as a plating catalyst on the surface of the sheet | seat 35. FIG.

In the printing, the opening 50 may be formed by printing in a predetermined pattern.

When printing the paste which functions as the said plating catalyst, it is preferable to form a shielding layer by printing a paste and forming the opening part 50, and then forming a metal film by an electroless plating method or an electroplating method.

As the paste that functions as the plating catalyst, a fluid containing a metal made of nickel, copper, chromium, zinc, gold, silver, aluminum, tin, cobalt, palladium, lead, platinum, cadmium, rhodium, or the like can be used.

(2) insulation layer forming process

Next, as shown in FIG. 5B, the insulating layer resin composition 45 is coated and cured on one surface of the shielding layer 30 to form the insulating layer 40.

As a method of coating the resin composition for insulating layers, a conventionally well-known coating method, for example, a gravure coat method, a kiss coat method, a die coat method, a lip coat method, a comma coat method, a blade coat method, a roll coat method, a knife coat method, A spray coat system, a bar coat system, a spin coat system, a dip coat system, etc. are mentioned.

As a method of hardening the resin composition for insulating layers, conventionally well-known various methods can be employ | adopted according to the kind of resin composition for insulating layers.

(3) Conductive Adhesive Layer Formation Step

Next, as shown in FIG. 5C, the conductive adhesive layer 20 is coated by coating the conductive adhesive layer composition 25 on the surface opposite to the surface on which the insulating layer 40 of the shielding layer 30 is formed. Form.

As a method of coating the composition 25 for conductive adhesive layers, a conventionally well-known coating method, for example, a gravure coat method, a kiss coat method, a die coat method, a lip coat method, a comma coat method, a blade coat method, a roll coat method, a knife A coat method, a spray coat method, a bar coat method, a spin coat method, a dip coat method, etc. are mentioned.

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

Next, an example of the method of manufacturing the electromagnetic wave shielding film 110 which is an example of the electromagnetic wave shielding film of this invention and a shielding layer consists of a copper layer and a silver layer is demonstrated.

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

These processes are explained in full detail below using FIGS.

(1) insulating layer preparation process

It is process drawing which shows typically an example of the insulating layer preparation process in the manufacturing method of the electromagnetic wave shielding film of this invention.

First, as shown in FIG. 6, the insulating layer 140 is prepared.

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

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

Next, the silver paste 133 is printed as a plating catalyst on one main surface of the insulating layer 140. At this time, a plurality of openings 150 having an opening area of 70 to 71000 µm ² and an opening ratio of 0.05 to 3.6% are formed in the silver paste.

As a method of printing the silver paste 133, a pattern is formed by intaglio printing such as gravure printing, iron plate printing such as flexographic printing, screen printing, intaglio, iron plate, screen, or the like. The method by the offset printing which transfers and forms what was formed, the method by the inkjet printing which a plate is unnecessary, etc. are mentioned.

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

7-9 is process drawing which shows typically an example of the silver paste printing process in the manufacturing method of the electromagnetic wave shielding film of this invention.

First, as shown in FIG. 7, the roll-shaped plate | board board 70 in which the some columnar protrusion part 72 was formed in the surface is prepared. At this time, the area of the upper surface 73 of each projection 72 is set to 70 to 71000 µm ² . Moreover, the some protrusion part 72 is formed so that the ratio of the total area of the upper surface 73 of the some projection part 72 with respect to the surface area of the plate 70 may be 0.05 to 3.6%.

In addition, the surface of the plate | board plate in which the protrusion part 72 is not formed is the protrusion part non-formation area 71.

In addition, the surface area of the plate | board 70 is the area of the protrusion part non-formation area | region 71 of the plate | board 70 in which the protrusion part 72 is not formed, and the total area of the upper surface 73 of the some protrusion part 72. Means total.

Next, as shown in FIG. 8, the silver paste 133 is taken into the protrusion non-forming region 71. At this time, the silver paste 133 is prevented from being applied to the upper surface 73 of the protrusion 72.

As shown in FIG. 9, the insulating layer 140 is allowed to pass between the impression cylinder 75 and the plate 70 in which the silver paste 133 has been taken in. The silver paste 133 is printed on one main surface.

In the printing, the silver paste 133 is not printed on the portion of the insulating layer 140 that the protrusions 72 reach, so that the opening 150 can be formed.

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

The silver paste 133 may contain various additives, such as a dispersing agent, a thickener, a leveling agent, and an antifoamer, in addition to the silver paste 133.

The shape of silver particle is not specifically limited, The material of arbitrary shapes, such as spherical shape, a flake shape, resin type, needle shape, fibrous form, can be used.

When the said silver particle is a particulate form, it is preferable that it is nano size. Specifically, silver particles having an average particle diameter in the range of 1 to 100 nm are preferable, and silver particles having a range of 1 to 50 nm are more preferable.

In addition, in this specification, an "average particle diameter" means the volume average value which diluted silver particle with the solvent for dispersion, and measured by the dynamic light scattering method.

For this measurement, "nano track UPA-150" manufactured by MicroTrack Corporation can be used.

Moreover, it is preferable that the thickness of the silver layer formed of the silver paste to print is 5-200 nm.

(3) copper plating process

FIG.10 (a) and FIG.10 (b) are process drawing which shows typically an example of the copper plating process in the manufacturing method of the electromagnetic wave shielding film of this invention.

Next, as shown in FIGS. 10A and 10B, the copper layer 132 is formed on the silver layer 131 by plating copper on the silver layer 131.

The plating method of copper is not specifically limited, Conventional electroless plating and electrolytic plating can be used.

When plating copper by electroless plating, it is preferable to use what contains a solvent, such as a copper sulfate, a reducing agent, and an aqueous medium, an organic solvent, as a plating liquid.

In the case of plating copper by the electrolytic plating method, by using copper sulfate, sulfuric acid, and an aqueous medium containing a plating solution as the plating solution, by controlling the plating treatment time, the current density, the amount of the additive used for plating, etc., so as to have a desired copper thickness. It is preferable to adjust.

It is preferable that the thickness of copper to plate is 0.1-10 micrometers.

Through the above process, the shielding layer 130 which consists of the silver layer 131 and the copper layer 132 can be formed.

(4) Conductive Adhesive Layer Formation Step

FIG.11 (a) and FIG.11 (b) are process drawing which shows typically an example of the conductive adhesive bond layer formation process in the manufacturing method of the electromagnetic wave shielding film of this invention.

11 (a) and 11 (b), FIG. 10 (b) is inverted up and down to show the subsequent steps.

Next, as shown in FIGS. 11A and 11B, the conductive adhesive layer composition 125 is coated on the copper layer 132 to form the conductive adhesive layer 120. As a method of coating the composition 125 for conductive adhesive layers, a conventionally well-known coating method, for example, a gravure coat method, a kiss coat method, a die coat method, a lip coat method, a comma coat method, a blade coat method, a roll coat method, a knife A coat method, a spray coat method, a bar coat method, a spin coat method, a dip coat method, etc. are mentioned.

After passing the above process, the electromagnetic wave shielding film 110 which is an example of the electromagnetic wave shielding film of this invention can be manufactured.

Although the Example which demonstrates this invention more concretely below is shown, this invention is not limited to these Examples.

(Preparation Example 1: Preparation Example of Silver Paste)

A silver paste having a silver concentration of 15% by mass was obtained by dispersing silver particles having an average particle diameter of 30 nm in a mixed solvent of 35 parts by mass of ethanol and 65 parts by mass of ion-exchanged water using a polyethyleneimine compound as a dispersant.

(Example 1)

(1) insulating layer preparation process

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

(2) silver paste printing process

Next, a plurality of openings having an opening area of 79 µm ² , an opening ratio of 0.15%, and an opening pitch of 250 µm were formed on one main surface of the insulating layer by using a roll-shaped plate as shown in FIGS. 7 to 9. The silver paste was printed to form a silver layer so that was formed.

And the thickness of the silver layer was 50 nm.

As the silver paste, the silver paste obtained in Preparation Example 1 was used.

In addition, the shape of the opening part was circular, and the arrangement pattern of the opening part was made into the arrangement pattern where the center of each opening part is located in the vertex of an equilateral triangle in the plane which arranged the regular triangle vertically and horizontally.

(3) copper plating process

Next, the insulating layer after silver paste printing was immersed for 20 minutes in an electroless copper plating solution ("ARG Copper" by Okuno Seiyaku Co., Ltd., pH 12.5) at 55 degreeC, and an electroless copper plating film (thickness 0.5 on a silver layer) Μm) was formed.

Subsequently, the surface of the electroless copper plating film obtained above is provided at the cathode, phosphorus containing copper is provided at the anode, and electroplating is carried out for 30 minutes at a current density of 2.5 A / dm 2 using an electroplating solution containing copper sulfate. The copper plating layer whose total thickness is 1 micrometer was laminated | stacked on the silver layer. As the electroplating solution, a solution of 70 g / liter of copper sulfate, 200 g / liter of sulfuric acid, 50 mg / liter of chlorine ions, and 5 g / liter of TOFLATINA SF (gloss produced by Okuno Seiyaku Kogyo Co., Ltd.) was used.

(4) Conductive Adhesive Layer Formation Step

The conductive adhesive layer which added 20 mass% of Ag coating Cu powder to the phosphorus containing epoxy resin was coated so that thickness might be set to 15 micrometers on the copper layer. As the coating method, a lip coat method was used.

The above process was passed and the electromagnetic wave shielding film which concerns on Example 1 was manufactured.

(Example 2) to (Example 36) and (Comparative Example 1) to (Comparative Example 30)

As in Example 1, except that the opening area, the opening ratio and the opening pitch of the opening, and the thickness of the copper layer were changed as shown in Tables 1 and 2, Examples 2 to 36 and Comparative Examples 1 to 1 were used. The electromagnetic wave shielding film which concerns on the comparative example 30 was manufactured.

TABLE 1

TABLE 2

(Evaluation of Electromagnetic Shielding Characteristics)

The electromagnetic shielding characteristics of the electromagnetic shielding film according to each example and each comparative example were evaluated by the KEC method using the electromagnetic shielding effect measuring apparatus 80 developed at the KEC Kansai Electronics Industry Promotion Center, which is a general corporation.

It is a schematic diagram which shows typically the structure of the system used by a KEC method.

The system used in the KEC method includes an electromagnetic wave shielding effect measuring apparatus 80, a spectrum analyzer 91, an attenuator 92 for attenuating 10 dB, an attenuator 93 for attenuating 3 dB, It consists of a preamp 94.

As shown in FIG. 12, two measuring jigs 83 are provided in the electromagnetic wave shielding effect measuring apparatus 80 so as to face each other. Between this measuring jig 83, it installs so that the electromagnetic wave shielding film (indicated by reference numeral "110" in FIG. 12) concerning each Example and each comparative example is clamped. In the measurement jig 83, the dimensional distribution of a TEM cell (Transverse Electro Magnetic Cell) is taken in, and it has a structure divided into left and right symmetry in the plane perpendicular | vertical to the transmission axis direction. However, in order to prevent the short circuit from being formed by the insertion of the electromagnetic shielding film 110, the flat center conductor 84 is formed with a gap formed between the respective measuring jigs 83.

In the KEC method, first, a signal output from the spectrum analyzer 91 is input to the measurement jig 83 on the transmission side via the attenuator 92. The signal is measured by the spectrum analyzer 91 after amplifying the signal through the attenuator 93 by the attenuator 93 on the receiving side of the measuring jig 83. And the spectrum analyzer 91 makes the electromagnetic wave shielding film 110 the electromagnetic wave shielding effect measuring apparatus 80 on the basis of the state which does not install the electromagnetic wave shielding film 110 in the electromagnetic wave shielding effect measuring apparatus 80. Output the attenuation when

Using such an apparatus, the electromagnetic wave shielding film which concerns on each Example and each comparative example was cut out to 15 cm in all directions on the conditions of 25 degreeC of temperature, and 30-50% of a relative humidity, and the measurement of the electromagnetic wave shielding characteristic in 200MHz was measured. It evaluated by doing.

Evaluation criteria are as follows. The results are shown in Table 1 and Table 2.

○: 85dB or more

×: less than 85dB

(Evaluation of Interlayer Peeling)

The electromagnetic wave shielding film which concerns on each Example and each comparative example was evaluated by the following method.

First, each electromagnetic shielding film was affixed on the printed wiring board by heat press.

Subsequently, after leaving this shielding printed wiring board in the clean room of 23 degreeC and 63% RH for 7 days, it exposed to the temperature conditions at the time of reflow, and evaluated the presence or absence of interlayer peeling. And as a temperature condition at the time of reflow, lead-free solder was assumed and the maximum temperature profile of 265 degreeC was set. In addition, the presence or absence of interlayer peeling passed the shielding printed wiring board five times through atmospheric reflow, and observed the presence or absence of expansion.

Evaluation criteria are as follows. The results are shown in Table 1 and Table 2.

○: No expansion occurred in the shielding film.

×: expansion occurred in the shielding film

(Evaluation of bending resistance)

The electromagnetic wave shielding film which concerns on each Example and each comparative example was evaluated by the following method.

Each electromagnetic shielding film was attached to both sides of a 50-micrometer-thick polyimide film by heat press, cut into the size of length X width = 130 mm x 15 mm, and it was set as a test piece, and the bending resistance of each test piece was MIT resistance fatigue Using a test machine (manufactured by Yasuda Seiki Seisakusho, No. 307 MIT Type Abrasion Resistance Tester), bending resistance was measured based on the method specified in JIS P8115: 2001.

Test conditions are as follows.

Bending clamp tip R: 0.38 mm

Bending Angle: ± 135 °

Bending Speed: 175cpm

Load: 500gf

Detection method: Detect disconnection of shielding film by built-in traditional device

In addition, the bending resistance evaluation criteria are as follows. The results are shown in Table 1 and Table 2.

◎: Disconnection occurred at more than 2000 bending times.

○: The disconnection occurred more than 600 times and less than 2000 times.

×: Disconnection occurred when the number of bending was less than 600.

As shown in Table 1 and Table 2, when the opening area of the opening is 70 to 71000 µm ² and the opening ratio of the opening is 0.05 to 3.6%, as in the electromagnetic shielding film according to each example, the evaluation of the electromagnetic shielding properties and the interlayer It was shown that both evaluation of peeling and evaluation of bending resistance were favorable.

10, 110: electromagnetic wave shielding film
20, 120: conductive adhesive layer
25, 125: composition for conductive adhesive layers
30, 130: shielding layer
40, 140: insulation layer
45: resin composition for insulating layer
50, 150 openings
70: Pandong
71: protrusion non-formation area
72: protrusion
73: upper surface of the protrusion
75: tenderness
80: electromagnetic wave shielding effect measuring device
83: Measuring Jig
84: center conductor
91: spectrum analyzer
92, 93: Attenuator
94: preamplifier
131: silver layer
132: copper layer
133: silver paste

Claims (9)

As an electromagnetic wave shielding film which consists of a conductive adhesive layer, the shielding layer laminated | stacked on the said conductive adhesive layer, and the insulating layer laminated | stacked on the said shielding layer,
A plurality of openings are formed in the shielding layer,
The opening area of the opening is 70 to 71000 µm ² , and
The opening ratio of the opening is 0.05 to 3.6%,
Electromagnetic shielding film. The method of claim 1,
The electromagnetic wave shielding film of the said opening part whose opening pitch is 10-10000 micrometers. The method according to claim 1 or 2,
Electromagnetic shielding film, the thickness of the shielding layer is 0.5㎛ or more. The method according to any one of claims 1 to 3,
The shielding layer, electromagnetic shielding film comprising a copper layer. The method of claim 4, wherein
The shielding layer further comprises a silver layer,
The silver layer is disposed on the insulating layer side,
The said copper layer is arrange | positioned at the said conductive adhesive bond layer side. The method according to any one of claims 1 to 5,
The electromagnetic wave shielding film is an electromagnetic wave shielding film for flexible printed wiring boards. A base member on which a printed circuit is formed;
A printed wiring board having an insulating film provided on the base member so as to cover the printed circuit; And
Electromagnetic shielding film installed on the printed wiring board
As a shielded printed wiring board comprising:
The electromagnetic wave shielding film is an electromagnetic wave shielding film according to any one of claims 1 to 6,
Shielded printed wiring board. The method of claim 7, wherein
The said printed wiring board is a flexible printed wiring board, The shielded printed wiring board. The electronic device which is assembled in the state which the shielded printed wiring board of Claim 7 or 8 was bent.

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