TWI858176B - Ground connection lead film - Google Patents

Abstract

The present invention provides a ground connection lead film that is not easy to peel off between the metal layer and the adhesive layer, and gas is not easy to accumulate between the metal layer and the adhesive layer when heated, or provides a ground connection lead film that can form the film. The ground connection lead film has a metal layer and an adhesive layer arranged on one surface of the metal layer. An opening portion that passes through the metal layer in the thickness direction is formed in the metal layer, and the opening portion has a cross section with a first width and a second width in the thickness direction cross section, the first width extends in the surface expansion direction and is relatively wide, and the second width extends in the surface expansion direction and is relatively narrow relative to the first width. The adhesive layer is deposited on the metal layer on the second width side relative to the first width. A portion of the adhesive layer may penetrate or has penetrated into the opening portion. When a portion of the adhesive layer has penetrated into the opening portion, the second width is buried in the adhesive layer in the opening portion.

Description

Ground connection lead film

Invention Field

The present invention relates to a ground connection lead film.

Background technology

In electronic devices such as mobile phones, video cameras, and laptops, printed wiring boards are widely used to install circuit assemblies in the mechanism. In addition, they are also used to connect movable parts such as print heads with control parts. In these electronic devices, electromagnetic wave shielding measures must be taken. For printed wiring boards used in the devices, shielded printed wiring boards with electromagnetic wave shielding measures have also begun to be used.

The shielded printed wiring board has the following structure, for example: the electromagnetic wave shielding film is placed on a base film containing a printed circuit in a manner that the electromagnetic wave shielding film is formed by sequentially stacking an adhesive layer, a metal thin film, and an insulating layer, and then the adhesive layer is bonded to the base film by heating and pressurizing (thermocompression bonding).

Furthermore, in order to release electromagnetic waves that penetrate into the shielded printed wiring board or electromagnetic waves generated in the shielded printed wiring board to the outside, a ground connection lead film is sometimes used. As the above-mentioned ground connection lead film, it is known that it is composed of a metal layer of a conductive substrate and an adhesive layer for sticking to any position in the shielded printed wiring board (for example, refer to patent documents 1 and 2).

Prior art literature

Patent Literature

Patent document 1: Japanese Patent Publication No. 2016-122687

Patent document 2: Japanese Patent Publication No. 2003-86907

Summary of invention

However, it is known that in the ground connection lead film, when the interlayer adhesion between the metal layer and the adhesive layer is weak, there is a problem that the metal layer and the adhesive layer are easily peeled off. In addition, when the ground connection lead film is hot-pressed to be attached to the shielded printed wiring board or printed wiring board, or when heated in the reflow step, the organic solvent remaining in the adhesive layer will evaporate to generate gas. Since the gas cannot pass through the metal layer, there is a problem that it is accumulated between the metal layer and the adhesive layer. If the solder is heated rapidly during the solder reflow step, the gas accumulated between the metal layer and the adhesive layer may expand or the adhesion between the metal layer and the adhesive layer may be destroyed.

A known method for preventing expansion caused by the generated gas is to use a metal layer formed with a plurality of openings. However, if the openings are provided, the contact area between the metal layer and the adhesive layer will be reduced, making it easier to cause peeling between the layers.

Therefore, the purpose of the present invention is to provide a ground connection lead-out film that is not easy to peel off between the metal layer and the adhesive layer, and gas is not easy to accumulate between the metal layer and the adhesive layer when heated, or to provide a ground connection lead-out film that can form such a film.

The inventors of the present invention have made careful studies to achieve the above-mentioned purpose, and found that in the ground connection lead-out film, by specifying the shape of the opening portion provided in the metal layer and the stacking morphology of the metal layer and the adhesive layer, it is not easy for the metal layer and the adhesive layer to peel off, and it is not easy for gas to accumulate between the metal layer and the adhesive layer when heated. The present invention is completed based on these insights.

That is, the present invention provides a ground connection lead film, which has a metal layer and an adhesive layer disposed on one surface of the metal layer, wherein an opening portion is formed on the metal layer and passes through the metal layer in the thickness direction, wherein the opening portion has a cross section having a first width and a second width in the thickness direction cross section, wherein the first width extends in the surface expansion direction and is relatively large relative to the upper width, and the second width extends in the surface expansion direction. The adhesive layer is relatively narrow relative to the first width. The adhesive layer is deposited on the metal layer on the second width side based on the first width. A portion of the adhesive layer may or has intruded into the opening. When a portion of the adhesive layer has intruded into the opening, the second width is buried in the adhesive layer that has intruded into the opening.

In the ground connection lead film, an opening portion is formed in the metal layer that passes through the thickness direction. When gas is generated in the adhesive layer during heating, the gas can pass through the metal layer through the opening portion, so the gas is not easily accumulated between the metal layer and the adhesive layer. Furthermore, the opening portion has a first width relative to the upper attribute width and a second width relative to the upper attribute narrowness, and the adhesive layer is laminated on the metal layer surface on the side of the second width relative to the upper attribute narrowness based on the first width. Then, in the first embodiment, a part of the adhesive layer is formed to be able to penetrate into the opening portion. The first embodiment can be transformed into the second embodiment by, for example, applying a heating/pressurization treatment. In the second embodiment, a portion of the adhesive layer will intrude into the opening, and the second width, which is relatively narrow, is buried in the adhesive layer that has intruded into the opening. In the second embodiment, even when a force is applied in the direction in which the metal layer and the adhesive layer are to be peeled off from each other, the adhesive in the opening will be stuck in the portion of the metal layer having the second width, thereby making it difficult for the adhesive in the opening and the adhesive outside the opening that is integral with the adhesive in the opening to be peeled off from the metal layer, and thus the adhesive layer is difficult to be peeled off from the metal layer.

The ground connection lead-out film of one embodiment of the present invention has the following effects: peeling between the metal layer and the adhesive layer is not easy to occur, and gas is not easy to accumulate between the metal layer and the adhesive layer when heated. In addition, the ground connection lead-out film of another embodiment of the present invention can form a ground connection lead-out film with such effects.

1,1’: Ground connection lead film

2:Metal layer

2a: Metal layer exposed

2b: Then the dosage form

3,3’,64,81: Next is the agent layer

5a,5b,5c: Shielded printed wiring board

6,6’: Printed wiring board

7,8: Shielding laminate

21: Opening

31: Conductive particles

61: Base component

62: Circuit diagram

62a:Signal circuit

62b: Ground circuit

63: Insulation protection layer (covering layer)

71: Conductive adhesive layer

72,83: Insulation layer

82:Electromagnetic wave shielding layer

D1: First width

D2: Second width

H: Surface expansion direction

T: thickness direction

b-b’: cross section in thickness direction

Figure 1(a) is an appearance diagram showing the first state of the ground connection lead-out film of the present invention, and Figure 1(b) is an enlarged view of the a-a’ cross section in the thickness direction.

Figure 2(a) is an appearance diagram showing the second state of the ground connection lead-out film of the present invention, and Figure 2(b) is an enlarged view of the b-b’ cross section in the thickness direction.

FIG3 is a cross-sectional view showing one embodiment of a shielded printed wiring board using the ground connection lead film shown in FIG1.

FIG4 is a cross-sectional view showing another embodiment of a shielded printed wiring board using the ground connection lead film shown in FIG1.

FIG5 is a cross-sectional view showing another embodiment of a shielded printed wiring board using the ground connection lead film shown in FIG1.

The form used to implement the invention

[Ground connection lead film]

In this manual, the so-called "ground connection lead film" means a film that can electrically connect the ground circuit of a printed wiring board to an external ground potential at any position on the printed wiring board, or a film that can connect the shielding layer of an electromagnetic wave shielding film to a ground potential located outside the shielded printed wiring board. As a film that can electrically connect the ground circuit of a printed wiring board to an external ground potential, a specific example is: a film that can connect the ground portion of a printed wiring board to a ground potential located outside the shielded printed wiring board at any position in a shielded printed wiring board on which an electromagnetic wave shielding film has been layered, or in a reinforced printed wiring board on which a conductive reinforced board has been layered.

FIG. 1 and FIG. 2 show an implementation form of the ground connection lead film. FIG. 1(a) is an appearance diagram showing the first state of the ground connection lead film of the present invention, and FIG. 1(b) is an enlarged view of the a-a' cross section in the thickness direction. The ground connection lead film 1 has a metal layer 2 and an adhesive layer 3 laminated on one surface 2b of the metal layer 2. The adhesive layer 3 can be laminated on only one surface of the metal layer 2, or on both surfaces.

As shown in Fig. 1(a) and (b), a plurality of openings 21 are formed in the metal layer 2 and penetrate the metal layer 2 in the thickness direction T. As shown in Fig. 1(b), the shape of the cross section of the opening 21 in the thickness direction T is a cone shape that expands in the direction away from the side of the adhesive layer 3. The above-mentioned cone shape has: a first width D1, which extends in the surface expansion direction H and is relatively wide; and a second width D2, which extends in the surface expansion direction H and is relatively narrow. In the metal layer 2, the first width D1 is located on the metal layer surface (metal layer exposed surface) 2a on the opposite side of the adhesive layer 3, and the second width D2 is located on the metal layer surface (adhesive layer accumulation surface) 2b on the side of the adhesive layer 3. In the first embodiment, a part of the adhesive layer 3 does not intrude into the opening 21, but a part of the adhesive layer 3 can be formed to intrude into the opening 21.

In addition, in this specification, the so-called "conical shape" means a shape whose width expands continuously from one direction in a cross-sectional shape and a shape whose cross-sectional shape expands continuously from one direction in a three-dimensional shape, and is not limited to a fixed increase in expansion. For example, the side of the conical shape shown in FIG. 1(b) may also be a curve. In addition, the cross-sectional shape of the opening portion 21 having the first width D1 and the second width D2 is not limited to a conical shape, and examples include shapes having a conical shape such as a funnel shape, and shapes having a convex shape, etc.

The ground connection lead film 1 of the first state is subjected to a heating/pressurizing treatment, for example, so that the adhesive layer 3 flows and invades the opening 21. Afterwards, it hardens to a degree that can fully exert the force to clamp the second width D2 to form the adhesive layer 3', and transforms into the ground connection lead film 1' of the second state shown in Figure 2. That is, the adhesive layer 3 preferably has the property of being fluid by heating and/or pressurizing, and the property of hardening after flowing (specifically, the property of being hardened to a degree that can fully exert the force to clamp the second width D2).

FIG2(a) is an external view showing the second state of the ground connection lead film of the present invention, and FIG2(b) is an enlarged view of the b-b' cross section in the thickness direction. As shown in FIG2(a) and (b), in the ground connection lead film 1', a portion of the adhesive constituting the adhesive layer 3' will intrude into each opening 21 provided in the metal layer 2. The interface of the adhesive layer 3' in the opening 21 is located closer to the adhesive layer 3' side (adhesive layer accumulation surface 2b side) than the first width D1 of the relative upper width in the cross section T in the thickness direction, and is located on the opposite side of the adhesive layer 3' side (metal layer exposed surface 2a side) relative to the second width D2 of the relative upper narrow width. That is, the interface of the adhesive layer 3' in the opening 21 is located on the first width D1 side (metal layer exposed surface 2a side, upper side of Figure 2(b)) based on the second width D2, and in the opening 21, the second width D2 is buried in the adhesive layer 3.

In the second embodiment, the ground connection lead film 1' is formed with an opening 21 penetrating in the thickness direction T through the metal layer 2. When gas is generated in the adhesive layer 3' during heating, the gas can pass through the metal layer 2 through the opening 21, so the gas is not easily accumulated between the metal layer 2 and the adhesive layer 3'.

Furthermore, in the second embodiment, the second width D2 is buried in the adhesive layer 3' in the opening 21, so that even when a force is applied in the direction in which the metal layer 2 and the adhesive layer 3' are to be peeled off from each other, the adhesive in the opening 21 will be stuck in the protrusion having the second width D2, so that the adhesive in the opening 21 and the adhesive outside the opening 21 that is integral with the adhesive in the opening 21 are not easy to be peeled off from the metal layer 2, and therefore the adhesive layer 3' is not easy to be peeled off from the metal layer 2. In addition, the interface of the adhesive layer 3' exists in the opening 21, and the adhesive layer 3 will not flow out from the exposed surface 2a of the metal layer. Therefore, when the metal layer 2 is connected to the frame of the electronic component, the resin component constituting the adhesive layer 3' will not hinder the contact between the frame and the metal layer 2. In addition, the interface of the adhesive layer 3' can also be exposed from the metal layer exposed surface 2a side and cover a part of the surface of the metal layer 2.

The interface of the adhesive layer 3' in the opening 21 is located between the first width D1 and the second width D2 in the thickness direction T of the metal layer 2. When the exposed surface 2a of the metal layer is the end of the width of the tapered shape and the interface of the adhesive layer 3' is located between the first width D1 and the second width D2, when the solder is formed on the opening 21, the gap between the periphery of the bottom surface of the solder with the solder and the edge of the opening is small, and it is not easy to have a gap, and the solder wettability on the surface of the adhesive layer 3' will be improved. In addition, from the perspective of increasing the amount of adhesive in the opening 21 and more fully clamping the adhesive, the interface of the adhesive layer 3' in the opening 21 can also be located on the first width D1.

The thickness direction T section shown in FIG. 1(b) or FIG. 2(b) is a section through the center and diameter of the circular opening 21 viewed from the side of the metal layer 2. By making the section through the center of the opening 21 the section shown in FIG. 1(b) or FIG. 2(b) (i.e., the section with the first width D1 and the second width D2), the adhesive in the opening 21 can be fully clamped in the second state. It is particularly desirable that all thickness direction T sections through the center of the opening 21 are the sections shown in FIG. 1(b) or FIG. 2(b). In addition, the sections that do not pass through the center may also be the sections shown in FIG. 1(b) or FIG. 2(b), and it is particularly desirable that all thickness direction T sections in the through-portion of the opening 21 are the sections shown in FIG. 1(b) or FIG. 2(b).

The opening 21 is in the following conical shape: the cross section in the surface expansion direction H continuously expands from the adhesive layer surface 2b toward the metal layer exposed surface 2a. With this shape, the adhesive in the opening 21 can be more fully clamped. In addition, it is easy to make an opening with a first width D1 and a second width D2 in the thickness direction T cross section.

From the perspective of being able to more fully clamp the adhesive in the opening 21, the length difference between the first width D1 and the second width D2 in the thickness direction T cross section should be greater than the thickness of the metal layer 2.

The following describes in detail the preferred embodiments of the ground connection lead-out films 1, 1', the metal layer 2 and the adhesive layers 3, 3'. In addition, in this specification, the ground connection lead-out films 1 and 1' are sometimes collectively referred to as "ground connection lead-out film group 1", and the adhesive layers 3 and 3' are sometimes collectively referred to as "adhesive layer group 3".

(Metal layer)

A plurality of openings 21 are formed in the metal layer 2. The shape of the opening 21 in the plane expansion direction H (i.e., the shape viewed from above in FIG. 1) is circular, or may be elliptical, track-shaped, polygonal (e.g., triangle, quadrangle, pentagon, hexagon, octagon, etc.), star-shaped, etc. From the perspective of the ease of forming the opening, a circular shape is preferred. In addition, the plurality of openings 21 may all be of the same shape, or may be of two or more different shapes.

There is no special restriction on the arrangement pattern of the openings 21, for example, a grid pattern, a houndstooth pattern, a honeycomb structure, etc. In addition, the openings 21 can be arranged regularly or irregularly.

The opening area of the opening 21 (the area of each opening) is not particularly limited. The maximum area in the surface expansion direction H is preferably 100-75000 μm ² , preferably 500-35000 μm ² , and more preferably 1000-20000 μm ² . If the opening area is greater than 100 μm ² , the air permeability will be better. If the opening area is less than 75000 μm ² , the ground connection lead performance will be better.

There is no special restriction on the opening ratio of the opening portion 21, which is preferably 0.5~40%, preferably 2.0~30%, and more preferably 4.0~25%. If the above opening ratio is above 0.5%, the air permeability will become better. If the above opening ratio is below 40%, the ground connection lead-out performance will become better.

The metals constituting the metal layer 2 include, for example, gold, silver, copper, aluminum, nickel, tin, palladium, chromium, titanium, zinc or alloys thereof. From the perspective of excellent ground connection performance, copper and silver layers are preferred, while from the perspective of economy, copper is preferred.

The metal layer 2 can be a single layer or a composite layer (e.g., a metal-plated layer). However, in the case of a composite layer, the opening 21 is provided at the same position in such a way as to penetrate the composite metal layer 2.

The thickness of the metal layer 2 is preferably 0.5~12μm, and more preferably 1~6μm. If the thickness is above 0.5μm, the opening portion and the ground connection lead-out performance will become better. If the thickness is below 12μm, the conformity to the substrate with uneven surfaces can be guaranteed, and the product with the ground connection lead-out film can be designed in a smaller size.

(followed by the agent layer)

The adhesive layer group 3 is used to bond, for example, the ground connection lead film group 1 to the shielded printed wiring board or printed wiring board. The adhesive layer group 3 may be a single layer or a multi-layer. The adhesive layer group 3 preferably contains an adhesive component. The above-mentioned adhesive component may be used alone or in combination of two or more.

The above-mentioned binder components can be listed as: thermoplastic resins, thermosetting resins, active energy ray-hardening compounds, etc. The above-mentioned thermoplastic resins can be listed as: polystyrene resins, vinyl acetate resins, polyester resins, polyolefin resins (such as polyethylene resins, polypropylene resin compositions, etc.), polyimide resins, acrylic resins, etc. The above-mentioned thermoplastic resins can be used alone or in combination of two or more.

Examples of the thermosetting resin include: a thermosetting resin (thermosetting resin) and a resin obtained by hardening the thermosetting resin. Examples of the thermosetting resin include: phenolic resins, epoxy resins, urethane resins, melamine resins, alkyd resins, etc. Only one type of the thermosetting resin may be used, or two or more types may be used.

Examples of the above-mentioned epoxy resins include bisphenol epoxy resins, spirocyclic epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, terpene epoxy resins, glycidyl ether epoxy resins, glycidyl amine epoxy resins, novolac epoxy resins, etc.

Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, tetrabromobisphenol A type epoxy resin, etc. Examples of the glycidyl ether type epoxy resin include tris(glycidoxyphenyl)methane, tetrakis(glycidoxyphenyl)ethane, etc. Examples of the glycidyl amine type epoxy resin include tetraglycidyl diamino diphenylmethane, etc. The above-mentioned novolac type epoxy resins include, for example: cresol novolac type epoxy resin, phenol novolac type epoxy resin, α-naphthol novolac type epoxy resin, brominated phenol novolac type epoxy resin, etc.

The above-mentioned active energy ray-hardening compounds can be exemplified as compounds that can be hardened by irradiation with active energy rays (active energy ray-hardening compounds) and compounds obtained by hardening the above-mentioned active energy ray-hardening compounds. There are no special restrictions on the active energy ray-hardening compounds, and examples thereof include polymerizable compounds having one or more (preferably two or more) free radical reactive groups (such as (meth)acryloyl groups) in the molecule. The above-mentioned active energy ray-hardening compounds can be used alone or in combination of two or more.

Among them, the above-mentioned adhesive component is preferably a thermosetting resin. In this case, after the ground connection lead film 1 is arranged on the adherend such as a printed wiring board or a shielded printed wiring board, the adhesive component can be hardened by applying pressure and heat, and the adhesion of the adhesive portion will become good. For example, when the adhesive component in the adhesive layer 3 is set to a thermosetting resin, the adhesive component in the adhesive layer 3' will become a thermosetting resin in which the above-mentioned thermosetting resin has been hardened.

When the above-mentioned adhesive component contains a thermosetting resin, the components constituting the above-mentioned adhesive component may also contain a hardener for promoting a thermosetting reaction. The above-mentioned hardener may be appropriately selected according to the type of the above-mentioned thermosetting resin. The above-mentioned hardener may be used only one type or two or more types.

The adhesive layer group 3 may also be conductive. When conductive, the ground connection lead-out performance becomes better. When conductive, the adhesive layer group 3 preferably includes conductive particles. The above-mentioned conductive particles may be used only one type or two or more types.

The above-mentioned conductive particles include, for example: metal particles, metal-coated resin particles, metal fibers, carbon fillers, carbon nanotubes, etc.

The metal particles and the metals constituting the coating of the metal-coated resin particles can be exemplified by: gold, silver, copper, nickel, zinc, indium, tin, lead, bismuth, and alloys containing two or more of these. Only one of the above metals can be used, or two or more can be used.

Specifically, the metal particles include, for example, copper particles, silver particles, nickel particles, silver-coated copper particles, indium particles, tin particles, lead particles, bismuth particles, gold-coated copper particles, silver-coated nickel particles, gold-coated nickel particles, indium-coated copper particles, tin-coated copper particles, lead-coated copper particles, bismuth-coated copper particles, indium-coated nickel particles, tin-coated nickel particles, bismuth-coated nickel particles, and silver-coated alloy particles. The silver-coated alloy particles include, for example, copper-containing alloy particles (e.g., copper alloy particles composed of an alloy of copper, nickel, and zinc) and silver-coated copper alloy particles. The above-mentioned metal particles can be produced by electrolysis, atomization, reduction, etc.

Among them, the above-mentioned metal particles are preferably silver particles, silver-coated copper particles, and silver-coated copper alloy particles. From the perspective of excellent conductivity, inhibiting oxidation and agglomeration of metal particles, and reducing the cost of metal particles, silver-coated copper particles and silver-coated copper alloy particles are particularly preferred.

Specifically, the above-mentioned metal-coated resin particles can be listed as: silver-coated resin particles, gold-coated resin particles, indium-coated resin particles, tin-coated resin particles, lead-coated resin particles, bismuth-coated resin particles, etc.

The shapes of the above-mentioned conductive particles can be listed as: spherical, flake (scale), branch-like, fiber-like, amorphous (polyhedron), etc.

The median diameter (D50) of the conductive particles is preferably 1-50 μm, more preferably 3-40 μm. If the median diameter is greater than 1 μm, the conductive particles have good dispersibility and aggregation can be suppressed, and are not easily oxidized. If the average particle size is less than 50 μm, the conductivity will be good.

When the adhesive layer group 3 has conductivity, the adhesive layer group 3 can be set as a layer with isotropic conductivity or anisotropic conductivity as needed.

When the adhesive layer 3 group has conductivity, the content ratio of the conductive particles is not particularly limited. Relative to the total amount of the adhesive layer 100 mass%, it is preferably 2-95 mass%, preferably 5-80 mass%, and more preferably 10-70 mass%. If the above content ratio is above 2 mass%, the conductivity will become better. If the above content ratio is below 95 mass%, the adhesive component can be contained in sufficient amount, and the adhesion to the adherend will become better.

Within the scope of the effect of the purpose of the present invention, the adhesive layer group 3 may also contain other components other than the above-mentioned components. The above-mentioned other components can be listed as well-known or commonly used components that can be contained in the adhesive layer. The above-mentioned other components can be, for example: hardening accelerator, plasticizer, flame retardant, defoaming agent, viscosity regulator, antioxidant, diluent, anti-settling agent, filler, colorant, leveling agent, coupling agent, ultraviolet absorber, adhesive resin, anti-caking agent, etc. The above-mentioned other components can be used alone or in combination.

The thickness of the adhesive layer 3 group is preferably 3~20μm, and more preferably 5~15μm. If the thickness is above 3μm, the bonding force to the adherend will become better. If the thickness is below 20μm, the cost can be suppressed, and the product with the ground connection lead film can be designed in a smaller size. In addition, the thickness of the adhesive layer 3' when the adhesive layer 3 starts to flow and invades the opening 21 is the thickness of the adhesive layer in the area that has not invaded.

The manufacturing method of the ground connection lead film group 1 shown in Figures 1 and 2 is described. When manufacturing the ground connection lead film 1 shown in Figure 1, first, the adhesive layer 3, for example, can be formed by applying (coating) an adhesive composition used to form the adhesive layer 3 on a temporary substrate such as a separator or a metal layer 2, and then removing the solvent and/or partially hardening it as needed.

In addition to the components contained in the adhesive layer 3, the adhesive composition includes a solvent (solvent). Examples of the solvent include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, dimethylformamide, etc. The solid component concentration of the adhesive composition can be appropriately set according to the thickness of the formed adhesive layer, etc.

The adhesive composition can be applied by a known coating method. For example, a gravure roller coater, a reverse roller coater, a contact roller coater, a die lip coater, an immersion roller coater, a rod coater, a knife coater, a spray coater, a notched wheel coater, a direct coater, a slit die coater, and the like can be used.

When the adhesive layer 3 is formed on the temporary substrate, the metal layer 2 having the opening 21 pre-set is then laminated on the surface of the adhesive layer 3 formed on the temporary substrate. The opening 21 can be formed by punching a metal plate (or metal layer) or by laser irradiation, or by other known or conventional methods. Furthermore, when the metal plate is made of an etchable material such as copper, an anti-etching agent having a pattern that can form the opening 21 can be arranged on the surface of the metal plate, and the opening 21 can be formed by etching. Furthermore, a conductive paste or a paste that functions as a plating catalyst can be printed on the surface of the metal plate. During the printing, the opening 21 can be formed by printing with a predetermined pattern. In the case of printing the above-mentioned paste having a function as a plating catalyst, after the opening 21 is formed by printing the paste, a metal film can be formed by electroless plating or electroplating to form the metal layer 2. Alternatively, a conductive paste or a paste having a function as a plating catalyst can be printed into a desired pattern on the surface of the adhesive layer 3 formed on the temporary substrate, and then a metal film can be formed by electroless plating or electroplating to form the metal layer 2.

Then, by subjecting the film on which the metal layer 2 is stacked on the adhesive layer 3 to a heating/pressurizing treatment (hot pressing), a portion of the adhesive constituting the adhesive layer 3 can penetrate into the opening 21 of the metal layer 2. Alternatively, the adhesive layer 3 of the ground connection lead film 1 can be attached to the printed wiring board using the adhesive layer 3 as an adhesive surface, and then hot pressing is performed to bond the ground connection lead film 1 to the printed wiring board. For example, the hot pressing at this time can also be used to form an adhesive layer 3', and at the same time, a portion of the adhesive constituting the adhesive layer 3' can penetrate into the opening 21 to produce the ground connection lead film 1'. The temperature during the hot pressing is preferably 100-200°C, preferably 120-190°C, and more preferably 140-180°C. Moreover, based on the surface pressure on the printed wiring board, the pressure is preferably 0.5-10MPa, preferably 1-8MPa, and more preferably 2-6MPa. The time is preferably more than 1min, preferably more than 2min, and more preferably more than 3min. In this way, a ground connection lead film 1 can be obtained.

As described above, the ground connection lead film of the present invention can be used for the purpose of releasing electromagnetic waves that invade or shield the printed wiring board, or the electromagnetic waves generated to the outside. The following shows an example in which the ground connection lead film 1 is applied to a shielded printed wiring board. In addition, in Figures 3 to 5, the opening 21 formed on the metal layer 2 is omitted.

[Shielded printed wiring board]

As shown in FIG3 , the shielded printed wiring board 5a belonging to the first embodiment of the shielded printed wiring board comprises: a printed wiring board 6; a shielding laminate 7 formed of an electromagnetic wave shielding film; and a ground connection lead film 1', which is located between the printed wiring board 6 and the shielding laminate 7.

The printed wiring board 6 has: a base member 61; a circuit pattern 62, which is partially arranged on the surface of the base member 61; an insulating protective layer (covering layer) 63, which covers the circuit pattern 62 and performs insulating protection; and an adhesive layer 64, which covers the circuit pattern 62 and is used to connect the circuit pattern 62 and the base member 61 and the insulating protective layer 63. The circuit pattern 62 includes a plurality of signal circuits 62a and a ground circuit 62b. Through holes are formed in the adhesive layer 64 and the insulating protective layer 63 on the ground circuit 62b for the purpose of ensuring conduction with the conductive adhesive layer 71 of the shielding laminate 7.

The shielding laminate 7 is a laminate of a conductive adhesive layer 71 and an insulating layer 72, and is provided on the printed wiring board 6 through the conductive adhesive layer 71. The shielding laminate 7 can be formed by attaching an electromagnetic wave shielding film to the printed wiring board 6 and then performing heat pressing. By the above-mentioned heat pressing, the conductive adhesive layer in the electromagnetic wave shielding film flows by heating and pressurizing, and fills the above-mentioned through hole provided on the grounding circuit 62b, so that the grounding circuit 62b and the conductive adhesive layer 71 can be connected.

In the shielded printed wiring board 5a, a portion of the ground connection lead film 1' is arranged between the printed wiring board 6 and the shielding laminate 7, and the conductive adhesive layer 71 of the shielding laminate 7 and the metal layer 2 of the ground connection lead film 1' are bonded and electrically connected. Another portion of the ground connection lead film 1' is that one side is placed on the printed wiring board 6 and the other side is exposed. The above-mentioned exposed area has the function of serving as an external connection conductive layer, and is electrically connected to an external grounding component at the exposed portion. In this way, the ground circuit 62b of the printed wiring board 6 can be connected to the ground potential outside the shielded printed wiring board 5a. The ground connection lead film 1' can be formed by bonding the ground connection lead film 1 to the printed wiring board 6 in a manner in which the adhesive layer 3 constitutes the bonding surface, and then performing hot pressing. By using the above-mentioned hot pressing, the adhesive layer 3 will flow due to heating and pressure, and fill the through hole set on the ground circuit 62b. When the adhesive layer 3 has conductivity, the ground circuit 62b and the adhesive layer 3' can be connected.

As a variation of the shielded printed wiring board 5a shown in FIG3, the following printed wiring board can be cited: it has: a printed wiring board 6; a conductive reinforcing member; and a ground connection lead film 1', which is located inside the conductive adhesive layer of the conductive reinforcing member, and the printed wiring board does not have an electromagnetic wave shielding layer. Referring to FIG3, the structure of the printed wiring board is explained. The conductive reinforcing member has a conductive substrate and a conductive adhesive layer provided on one surface of the conductive substrate. The conductive adhesive layer in the conductive reinforcing member will adhere to the ground circuit 62b on the printed wiring board 6, and a portion of the conductive adhesive layer will fill the through hole on the ground circuit 62b. A portion of the ground connection lead film 1' is inside the conductive adhesive layer of the conductive reinforcement member, and is configured to be located between the conductive substrate and the printed wiring board 6. The conductive adhesive layer of the conductive reinforcement member and the metal layer 2 of the ground connection lead film 1' are electrically connected. Another portion of the ground connection lead film 1' is one side of which is placed on the printed wiring board 6, and a portion of the other side is exposed. The exposed area has the function of an external connection conductive layer, and is electrically connected to the external grounding member at the exposed portion. In this way, the ground circuit 62b of the printed wiring board 6 can be connected to the external ground potential through the conductive adhesive layer of the conductive reinforcement member and the metal layer 2 of the ground connection lead film 1'.

FIG4 shows another embodiment of a shielded printed wiring board using a ground connection lead film. As shown in FIG4, a shielded printed wiring board 5b belonging to the second embodiment of the shielded printed wiring board comprises: a printed wiring board 6; a shielding laminate 7 disposed on the printed wiring board 6; and a ground connection lead film 1' disposed on the shielding laminate 7. The adhesive layer 3' of the ground connection lead film 1' contains conductive particles 31, and the conductive particles 31 penetrate the insulating layer 72 of the shielding laminate 7 and contact the conductive adhesive layer 71. In addition, the conductive particles 31 contact the metal layer 2. By having such a structure, the shielding laminate 7 and the ground connection lead film 1' are electrically connected through the conductive particles 31, and the metal layer 2 has the function of being an external connection conductive layer, and the surface of the metal layer 2 is electrically connected to the external grounding component. In this way, the ground circuit 62b of the printed wiring board 6 can be connected to the ground potential located outside the shielding printed wiring board 5b. The ground connection lead film 1' can be formed by bonding the ground connection lead film 1 to the electromagnetic wave shielding laminate 7 of the shielding printed wiring board in a manner that the adhesive layer 3 constitutes the bonding surface, and then performing hot pressing to allow the conductive particles 31 to penetrate the insulating layer 72, and at the same time, the adhesive layer 3 is bonded to the shielding laminate 7. In addition, the shielding printed wiring board before the ground connection lead film 1' is provided can be manufactured in the same manner as described in the manufacturing method of the shielding printed wiring board 5a.

FIG5 shows another embodiment of a shielded printed wiring board using a ground connection lead film. As shown in FIG5, a shielded printed wiring board 5c belonging to the third embodiment of the shielded printed wiring board comprises: a printed wiring board 6'; a shielding laminate 8, which is disposed on the printed wiring board 6'; and a ground connection lead film 1', which is disposed on the shielding laminate 8. The printed wiring board 6' is the same as the printed wiring board 6, except that the circuit pattern 62 is composed of a plurality of signal circuits 62a, does not include a ground circuit 62b, and does not have a through hole. In addition, the circuit pattern 62 in FIG5 is illustrated in a state without including a ground circuit 62b, but may also include a ground circuit 62b.

The shielding laminate 8 is laminated with a non-conductive adhesive layer 81, an electromagnetic wave shielding layer 82 composed of a conductor, and an insulating layer 83 in this order, and is arranged on the printed wiring board 6' through the adhesive layer 81. The shielding laminate 8 can be formed by attaching an electromagnetic wave shielding film to the printed wiring board 6' and then performing heat pressing as needed.

The adhesive layer 3' of the ground connection lead film 1' contains conductive particles 31, and the conductive particles 31 penetrate the insulating layer 83 of the shielding laminate 8 and contact the electromagnetic wave shielding layer 82. In addition, the conductive particles 31 contact the metal layer 2. By having such a structure, the electromagnetic wave shielding layer 82 and the ground connection lead film 1' are electrically connected through the conductive particles 31, and the metal layer 2 has the function of serving as an external connection conductive layer, and the surface of the metal layer 2 is electrically connected to the external grounding component. In this way, the electromagnetic wave shielding layer 82 of the shielding laminate 8 and the ground potential located outside the shielding printed wiring board 5c can be connected, and the electromagnetic wave shielding layer 82 exerts an electromagnetic wave shielding function. The ground connection lead film 1' can be formed by bonding the ground connection lead film 1 to the electromagnetic wave shielding laminate 8 of the shielding printed wiring board by forming a bonding surface with an adhesive layer 3, and then performing heat pressing to allow the conductive particles 31 to penetrate the insulating layer 83 and simultaneously allow the adhesive layer 3 to bond to the shielding laminate 8. In addition, the shielding printed wiring board before the ground connection lead film 1' is provided can be manufactured in the same manner as described in the manufacturing method of the shielding printed wiring board 5a.

1’: Ground connection lead film

2:Metal layer

2a: Metal layer exposed

2b: Then the dosage form

3’: Next is the agent layer

21: Opening

D1: First width

D2: Second width

H: Surface expansion direction

T: thickness direction

b-b’: cross section in thickness direction

Claims (7)

A ground connection lead film comprises a metal layer and an adhesive layer disposed on one surface of the metal layer; an opening portion is formed on the metal layer and passes through the metal layer in the thickness direction; the opening portion has a cross section with a first width and a second width in the thickness direction cross section, the first width extends in the surface expansion direction and is relatively wide, and the second width extends in the surface expansion direction and is relatively wide relative to the first width. The first width is located on the metal layer on the opposite side of the adhesive layer. The adhesive layer is deposited on the metal layer on the second width side based on the first width. A portion of the adhesive layer may or has invaded the opening. When a portion of the adhesive layer has invaded the opening, the second width is buried in the adhesive layer that has invaded the opening. The ground connection lead-out film of claim 1, wherein the opening has a conical shape in the thickness direction cross section, the conical shape includes the first width and the second width, and expands in a direction away from the adhesive layer side. A ground connection lead-out film as claimed in claim 1 or 2, wherein the second width is located on the metal layer on the side of the adhesive layer. The ground connection lead-out film of claim 1 or 2, wherein the aforementioned cross section in the thickness direction is a conical shape, the conical shape includes the aforementioned first width and the aforementioned second width, and expands in a direction away from the aforementioned adhesive layer side. A ground connection lead-out film as claimed in claim 1 or 2, wherein the opening portion includes a conical shape, and the conical shape expands in a direction away from the side of the adhesive layer. For example, the ground connection lead film of claim 1 or 2, wherein the length difference between the aforementioned first width and the aforementioned second width is greater than the thickness of the aforementioned metal layer. The ground connection lead-out film of claim 1 or 2 has a plurality of the aforementioned openings, and the opening ratio of the aforementioned openings is 0.5~40%.