Conductive laminate

Abstract

Provided is a conductive laminate which has excellent electromagnetic shielding properties and has cushioning properties even if the conductive laminate is thin.　A conductive laminate 1 comprises a conductive substrate 2 and a conductive pressure-sensitive adhesive layer 3 laminated on at least one surface of the conductive substrate 2. The conductive substrate 2 includes a conductive adhesive layer 22. At least one conductive adhesive layer 22 has a gap A with respect to the adjacent layer.

Description

Conductive laminate

[0001] The present invention relates to a conductive laminate.

[0002] With the progress of miniaturization and high-density packaging of electronic devices, electronic components incorporated in electronic devices have also become higher in function, higher in density, higher in integration and more composite. As a result, noise, interference and other problems caused by electromagnetic waves occur frequently, and a member having electromagnetic shielding properties (a shielding member) is sometimes provided inside electronic devices. The shielding member is provided to cover electronic components such as semiconductor chips mounted on a substrate, in order to prevent each electronic component from emitting or receiving electromagnetic waves. Furthermore, when high-level shielding performance is required, the shielding member may be provided to individually cap each electronic component.

[0003] Furthermore, shielding members used inside miniaturized electronic devices are sometimes required to have cushioning properties to absorb design tolerances of electronic components, housings, and other components and conform to each member when subjected to external pressure. As such a shielding member, for example, a foam composite is known that includes a resin foam sheet containing a thermally conductive filler, a conductive sheet, an adhesive layer for bonding the conductive sheet and the resin foam sheet, and a conductive adhesive layer provided on the conductive sheet (see Patent Document 1).

[0004] Japanese Unexamined Patent Application Publication No. 2018-171916

[0005] In recent years, further miniaturization of electronic devices has been demanded, and the space for attaching shielding members inside electronic devices has also become smaller. However, the foam composite of Patent Document 1 has a multilayer structure including a foam sheet, so it tends to be thick, and has the problem that it cannot be used when the space for attaching the shielding member is narrow.

[0006] Accordingly, an object of the present invention is to provide a conductive laminate that is excellent in electromagnetic shielding properties and has cushioning properties even when it is thin.

[0007] The present invention provides a conductive laminate comprising a conductive substrate containing a conductive adhesive layer and a conductive adhesive layer laminated on at least one surface of the conductive substrate, wherein the conductive adhesive layer has a gap between adjacent layers.

[0008] The above conductive substrate may include a conductive nonwoven fabric.

[0009] The conductive adhesive layer has an uneven surface, and the recesses of the uneven surface may correspond to the voids.

[0010] Preferably, the conductive adhesive layer and the conductive adhesive layer are laminated adjacent to each other, and there is a gap between the conductive adhesive layer and the conductive adhesive layer.

[0011] The conductive substrate comprises at least two layers in total, consisting of a conductive nonwoven fabric and / or a conductive adhesive layer, wherein at least one of the two layers is a conductive adhesive layer, and the above-mentioned void may be present between the two layers.

[0012] The conductive laminate may have a configuration in which the conductive substrate, the conductive adhesive layer, the conductive substrate, and the conductive adhesive layer are laminated in this order.

[0013] The conductive laminate has a structure in which the conductive adhesive layer, the conductive tack layer, the conductive adhesive layer, and the conductive tack layer are laminated in this order, and the conductive tack layer located between the two conductive adhesive layers may be embedded in the conductive adhesive layer.

[0014] The conductive laminate described above is preferably used by stacking it so as to cover the holes in the shielding member that covers the electronic components mounted on the substrate.

[0015] Furthermore, the present invention provides an electronic device comprising a substrate, electronic components mounted on the substrate, a shielding member covering the electronic components and having a hole in the upper part of at least one of the electronic components, and a conductive laminate stacked on the shielding member so as to cover the hole in the shielding member.

[0016] The above electronic device may further include a housing that sandwiches the conductive laminate between the shielding member.

[0017] The conductive laminate of the present invention exhibits excellent electromagnetic shielding properties and cushioning even when thin. Therefore, the thickness of the conductive laminate can be changed by external pressure, regardless of whether it is thick or thin, and it can conform well to the substrate and exhibit excellent electromagnetic shielding properties even when used in the limited space of electronic equipment.

[0018] This is a partial cross-sectional view showing one embodiment of the conductive laminate of the present invention. This is a partial cross-sectional view showing another embodiment of the conductive laminate of the present invention. This is a partial cross-sectional view showing another embodiment of the conductive laminate of the present invention. This is a partial cross-sectional view showing another embodiment of the conductive laminate of the present invention. This is a partial cross-sectional view showing another embodiment of the conductive laminate of the present invention. This is a partial cross-sectional view of an electronic device using the conductive laminate of the present invention.

[0019] [Conductive Laminate] A conductive laminate according to one embodiment of the present invention comprises a conductive substrate and a conductive adhesive layer laminated on at least one surface of the conductive substrate. The conductive adhesive layer may be laminated on only one surface of the conductive substrate or on both surfaces. Furthermore, the conductive laminate may exhibit conductivity between both end surfaces (from one end surface to the other end surface). In this case, the conductive laminate does not have a layer that does not exhibit conductivity on both surfaces, and has excellent electrical connectivity.

[0020] The conductive substrate described above includes at least a conductive adhesive layer. The conductive substrate may further include a conductive layer such as a conductive nonwoven fabric or a metal foil. If the conductive layer is included, there may be only one conductive layer or two or more conductive layers.

[0021] The conductive substrate is preferably composed of a conductive nonwoven fabric and / or a conductive adhesive layer. That is, it is preferable that the conductive substrate does not contain any layers other than the conductive nonwoven fabric and the conductive adhesive layer. The conductive substrate may consist only of the conductive adhesive layer, or it may contain both the conductive adhesive layer and the conductive nonwoven fabric. Furthermore, in the conductive substrate, the conductive nonwoven fabric and the conductive adhesive layer may each consist of only one layer or two or more layers.

[0022] In this specification, the "adhesive layer" is a sheet-like pressure-sensitive adhesive having a layered shape, which deforms under external pressure and exhibits fluidity. The "adhesive layer" is a sheet-like adhesive having a layered shape, which exhibits adhesion to other layers when bonded to them and cured, and exhibits fluidity under external pressure after curing. In the conductive laminate having a structure in which the adhesive layer is laminated with other layers, the adhesive layer may be present either before or after curing.

[0023] At least one conductive adhesive layer has a void between it and an adjacent layer. Here, "adjacent layer" refers to any layer constituting the conductive laminate, and does not include the release film described later. Furthermore, the conductive nonwoven fabric has voids that penetrate from the surface to the interior. By providing a conductive nonwoven fabric or conductive adhesive layer with such voids, when subjected to external pressure, the conductive adhesive layer adjacent to these layers flows into the voids, allowing it to be compressed in the thickness direction. For this reason, the conductive laminate can be made thin by having such a simple layer structure and has excellent cushioning properties in the thickness direction.

[0024] The conductive laminate may include a release film. The release film may be provided on only one side of the conductive laminate or on both sides. Examples of the release film include a film formed from a low-tack resin or a sheet comprising a release treatment layer provided on the surface of the film. The release film is peeled off and removed when the conductive laminate is used.

[0025] Figures 1 to 6 show one embodiment of the conductive laminate described above. In Figure 1, the conductive laminate 1 consists of a conductive substrate 2 and a conductive adhesive layer 3. In Figure 1, the conductive substrate 2 consists of a conductive adhesive layer 21. The conductive adhesive layer 21 has a void A between it and the adjacent conductive adhesive layer 3. The surface of the conductive adhesive layer 21 that is adjacent to the conductive adhesive layer 3 is an uneven surface, and the recesses in this uneven surface correspond to the void A. Since the conductive adhesive layer 21 and the conductive adhesive layer 3 are laminated adjacent to each other and have a void A between the layers, external pressure can cause the conductive adhesive layer 3 to flow into the voids within the void A and be compressed in the thickness direction. In particular, the conductive adhesive layer has higher fluidity. For this reason, it is preferable that the uneven surface of the conductive adhesive layer is on the conductive adhesive layer side. That is, it is preferable that the adjacent layer is a conductive adhesive layer.

[0026] A conductive adhesive layer having an uneven surface can be manufactured by known or conventional methods, such as forming a conductive adhesive layer on a release film having an uneven shape for transfer, forming it by embossing the surface of a conductive adhesive layer formed on a release film, or forming it by making some of the conductive particles incorporated into the conductive adhesive layer protrude from the surface of the adhesive layer.

[0027] In the conductive laminate 1 shown in Figure 2, the conductive substrate 2 is composed of two conductive adhesive layers 211 and 212. The conductive adhesive layers 211 and 212 are adjacent to each other, and the surfaces that are in contact with each other are uneven surfaces, with voids A formed by the depressions in these uneven surfaces. Because there is a void A between the two conductive adhesive layers 211 and 212, external pressure causes the conductive adhesive layer 211 and / or conductive adhesive layer 212 to flow into the voids within void A and be compressed in the thickness direction. The uneven surface of the conductive adhesive layer 211 may be on the conductive adhesive layer 3 side or on both sides. In addition, one of the conductive adhesive layer 211 and conductive adhesive layer 212 may be a conductive nonwoven fabric. Thus, when the conductive substrate contains at least two layers in total, consisting of a conductive nonwoven fabric and / or conductive adhesive layers, it is preferable that at least one layer is a conductive adhesive layer, and that there is a void between the two layers.

[0028] In the conductive laminate 1 shown in Figure 3, the conductive substrate 2 is composed of two conductive adhesive layers 211 and 212. The conductive adhesive layers 211 and 212 are adjacent to each other and have a void A1 at the interface between the two layers. The surface of the conductive adhesive layer 211 adjacent to the conductive adhesive layer 3 is an uneven surface, and the recesses in this uneven surface correspond to voids A2. Because the conductive laminate 1 has a void A1 between the two conductive adhesive layers 211 and 212, external pressure causes the conductive adhesive layer 211 and / or conductive adhesive layer 212 to flow into the voids within void A1, and the conductive adhesive layer 3 to flow into the voids within void A2, allowing it to be compressed in the thickness direction. One of the conductive adhesive layer 211 and conductive adhesive layer 212 may be a conductive nonwoven fabric.

[0029] The conductive substrate 2 shown in Figure 3 can be manufactured, for example, by stacking two conductive adhesive layers and heat-laminating them using two rolls. Specifically, by heat-laminating the two stacked conductive adhesive layers using an embossing roll and a metal roll, the embossed shape of the embossing roll is transferred to the surface of one of the conductive adhesive layers. In addition, the parts where the convex part of the embossed surface of the embossing roll is nipped by the metal roll adhere closely to each other, while in the parts where the concave part of the embossed surface of the embossing roll is nipped by the metal roll, the two conductive adhesive layers do not adhere closely to each other, forming a gap A1. In this way, a conductive adhesive layer 211 that provides an embossed surface with an uneven shape and a conductive adhesive layer 212 that provides a smooth surface are laminated, and a conductive substrate 2 having a gap A1 between the conductive adhesive layers 211 and 212 is obtained. Then, the conductive laminate shown in Figure 3 can be manufactured by bonding such a conductive substrate 2 to a conductive adhesive layer 3.

[0030] The conductive laminate 1 in Figure 4 is the same as the conductive laminate 1 in Figure 3, except that a conductive adhesive layer 32 fills the void A1 in the conductive laminate 1 of Figure 3. The conductive laminate 1 in Figure 4 has a structure in which a conductive adhesive layer 212, a conductive adhesive layer 32, a conductive adhesive layer 211, and a conductive adhesive layer 31 are laminated in this order. The conductive adhesive layer 32 located between the two conductive adhesive layers 211 and 212 is embedded in the conductive adhesive layers 211 and 212. The conductive laminate 1 can be compressed in the thickness direction by external pressure causing the conductive adhesive layer 31 to flow into the void A, and by the compression of the conductive adhesive layer 32 embedded between the two conductive adhesive layers 211 and 212. One of the conductive adhesive layers 211 and 212 may be a conductive nonwoven fabric.

[0031] The conductive substrate 2 shown in Figure 4 can be manufactured, for example, by thermal laminating a three-layer sheet, in which a conductive adhesive layer is sandwiched between two conductive adhesive layers, using two rolls. Specifically, by thermal laminating the stacked three-layer sheet using an embossing roll and a metal roll, the embossed shape of the embossing roll is transferred to the surface of one of the conductive adhesive layers. In the portion where the convex part of the embossed surface of the embossing roll is nipped by the metal roll, the two conductive adhesive layers adhere closely together, the sandwiched conductive adhesive layer is pushed out, and an interface in which the conductive adhesive layers adhere closely together is formed. On the other hand, in the portion where the concave part of the embossed surface of the embossing roll is nipped by the metal roll, the two conductive adhesive layers do not adhere to each other, and the sandwiched conductive adhesive layer remains. In this way, a conductive substrate 2 is obtained in which a conductive adhesive layer 211 providing an embossed surface with an uneven shape and a conductive adhesive layer 212 providing a smooth surface are laminated, and a conductive adhesive layer 32 exists between the conductive adhesive layers 211 and 212. Then, by bonding such a conductive substrate 2 and a conductive adhesive layer 31, the conductive laminate shown in Figure 4 can be manufactured.

[0032] The conductive laminate 1 in Figure 5 is composed of two conductive substrates 2 and two conductive adhesive layers 3. Specifically, it has a structure in which conductive substrate 2 (conductive adhesive layer 212), conductive adhesive layer 3 (conductive adhesive layer 33), conductive substrate 2 (conductive adhesive layer 211), and conductive adhesive layer 3 (conductive adhesive layer 31) are laminated in this order. The two conductive adhesive layers 211 and 212 are adjacent to the conductive adhesive layer 33. The surface of conductive adhesive layer 212 on the side adjacent to the conductive adhesive layer 33 is an uneven surface, and the recesses in this uneven surface correspond to voids A1. Similarly, the surface of conductive adhesive layer 211 on the side adjacent to the conductive adhesive layer 33 is an uneven surface, and the recesses in this uneven surface correspond to voids A2. The conductive laminate 1 can be compressed in the thickness direction by external pressure, as the conductive adhesive layers 31 and 33 flow into the voids A1 and A2. In Figure 6, at least one of the conductive adhesive layer 211 and the conductive adhesive layer 212 may be a conductive nonwoven fabric.

[0033] The conductive laminate 1 shown in Figures 1 to 5 is a so-called "single-sided adhesive sheet" in which a conductive substrate 2 provides one end face and a conductive adhesive layer 3 provides the other end face. However, it may also be a so-called "double-sided adhesive sheet" in which a conductive adhesive layer is further bonded to the end face of the conductive substrate 2, so that both end faces are provided by the conductive adhesive layer.

[0034] As shown in Figures 3 to 5, the conductive laminate may consist of only one conductive substrate and one conductive adhesive layer, or it may consist of two or more layers. If it consists of two or more layers, the multiple conductive substrates or multiple conductive adhesive layers may have the same or different thicknesses, compositions, physical properties, and configurations.

[0035] <Conductive Substrate> (Conductive Adhesive Layer) The conductive adhesive layer preferably contains a conductive filler and a binder component. The binder component is a component that forms the matrix of the conductive adhesive layer.

[0036] Examples of the binder components mentioned above include thermoplastic resins, thermosetting resins, and active energy ray curing resins. Only one type of binder component may be used, or two or more types may be used.

[0037] Examples of the thermoplastic resins mentioned above include polystyrene resins, vinyl acetate resins, polyester resins, polyolefin resins (e.g., polyethylene resins, polypropylene resin compositions, etc.), polyimide resins, and acrylic resins. Only one type of thermoplastic resin may be used, or two or more types may be used.

[0038] The above-mentioned thermosetting resins include both thermosetting resins and resins obtained by curing the above-mentioned thermosetting resins. Examples of the above-mentioned thermosetting resins include silicone resins, phenolic resins, epoxy resins, urethane resins, urethane urea resins, melamine resins, alkyd resins, polyimide resins, and acrylic resins. Only one type of the above-mentioned thermosetting resin may be used, or two or more types may be used.

[0039] The above-mentioned active energy ray curable resin includes both a resin that can be cured by irradiation with active energy rays (active energy ray curable resin) and a resin obtained by curing the above-mentioned active energy ray curable resin. The above-mentioned active energy ray curable resin is not particularly limited, but for example, a polymer of a polymerizable compound having at least two (meth)acryloyloxy groups in its molecule can be used. The above-mentioned active energy ray curable resin may be used by one type only, or by two or more types.

[0040] The content ratio of the above binder component is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 45% by mass, based on the total amount (100% by mass) of the conductive adhesive layer. When the blending ratio of the binder component is within the above range, the flexibility is appropriate, and it can exhibit appropriate fluidity under external pressure.

[0041] Examples of the conductive fillers mentioned above include metal particles, metal-coated resin particles, metal fibers, carbon fillers, and carbon nanotubes. Only one type of conductive filler may be used, or two or more types may be used.

[0042] Examples of the metal constituting the metal particles and the coating portion of the metal-coated resin particles include gold, silver, copper, nickel, zinc, indium, tin, lead, bismuth, and alloys containing two or more of these. Only one kind of the above metal may be used, or two or more kinds may be used.

[0043] Specific examples of the above metal particles include copper particles, silver particles, nickel particles, silver-coated copper particles, indium particles, tin particles, lead 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. Examples of the above silver-coated alloy particles include silver-coated copper alloy particles in which alloy particles containing copper (for example, copper alloy particles made of an alloy of copper, nickel and zinc) are coated with silver. The above metal particles can be produced by an electrolytic method, an atomization method, a reduction method, or the like.

[0044] Examples of the shape of the above conductive filler include spherical shapes (true spherical shape, elliptical spherical shape, etc.), flake shapes (scale shape, flat shape), dendritic shape, fibrous shape, amorphous shape (polyhedron, etc.), and the like. Among these, a spherical shape is preferable from the viewpoint of better conductivity in the thickness direction.

[0045] The content ratio of the above conductive filler is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, still more preferably 55 to 80% by mass, relative to the total amount (100% by mass) of the above conductive adhesive layer. When the content ratio is 40% by mass or more, the electromagnetic shielding property is excellent. When the content ratio is 90% by mass or less, the flexibility becomes appropriate, and appropriate fluidity can be exhibited against external pressure.

[0046] The above conductive adhesive layer preferably contains a curing agent. The above curing agent has a role of curing at least one curable component in the binder component. Only one kind of the above curing agent may be used, or two or more kinds may be used.

[0047] Examples of the curing agents mentioned above include isocyanate-based curing agents, phenol-based curing agents, imidazole-based curing agents, amine-based curing agents, and cationic curing agents.

[0048] Furthermore, it is preferable that the conductive adhesive layer contains a curing accelerator. Examples of curing accelerators include imidazole-based curing accelerators. One type of curing accelerator may be used, or two or more types may be used.

[0049] Examples of the curing accelerators mentioned above include compounds in which an alkyl group, an ethyl cyano group, a hydroxyl group, an azine, etc., is added to an imidazole ring, such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-heptadecylimidazole, 2,4-diamino-6-(2'-undecylimidazolyl)ethyl-S-triazine, 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole, 5-cyano-2-phenylimidazole, 2,4-diamino-6-[2'methylimidazolyl-(1')]-ethyl-S-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, and 1-cyanoethyl-2-phenyl-4,5-di(2-cyanoethoxy)methylimidazole.

[0050] The conductive adhesive layer described above may contain other components besides those described above, as long as they do not impair the effects of the present invention. Examples of these other components include components found in known or conventional adhesive compositions. Examples of these other components include defoamers, leveling agents, thickeners, adhesives, fillers, flame retardants, colorants, fillers other than the conductive filler described above, etc. Only one of these other components may be used, or two or more may be used.

[0051] The thickness (total thickness) of the conductive adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, from the viewpoint of superior cushioning properties. Furthermore, from the viewpoint of being able to make the thickness (total thickness) of the conductive adhesive layer thinner, it may be, for example, 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less.

[0052] As described above, it is preferable that the conductive adhesive layer has an uneven surface on at least one surface. When there is a layer adjacent to the surface with the uneven surface, the adjacent layer (conductive adhesive layer, conductive adhesive layer, etc.) can flow into the recesses when subjected to external pressure, thereby providing cushioning. However, if the conductive laminate can provide cushioning by other means, the conductive adhesive layer does not need to have the above-mentioned uneven surface. Examples of the above-mentioned uneven surface include an embossed shape and a shape in which a part of a filler such as a conductive filler protrudes from the surface of the conductive adhesive layer.

[0053] The conductive adhesive layer described above can be manufactured by known or conventional manufacturing methods. For example, an adhesive composition for forming the conductive adhesive layer can be applied to a temporary substrate such as a release film, and if necessary, the layer can be formed by desolvation and / or partial curing.

[0054] The above adhesive composition may contain, for example, a solvent in addition to the components that can be included in the conductive adhesive layer described above. Examples of solvents include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The solid content concentration of the adhesive composition is appropriately set according to the thickness of the conductive adhesive layer to be formed.

[0055] A known coating method may be used to apply the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, lip coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, direct coaters, and slot die coaters may be used.

[0056] (Conductive Nonwoven Fabric) Examples of conductive nonwoven fabrics in the conductive substrate include those in which a metal layer is formed on the surface of a resin nonwoven fabric (conductive nonwoven fabric A) and those in which the fibers constituting the nonwoven fabric include conductive threads (conductive nonwoven fabric B). Among these, conductive nonwoven fabric A is preferred from the viewpoint of having excellent electromagnetic wave shielding properties and high flexibility and cushioning properties of the conductive laminate.

[0057] The conductive nonwoven fabric A comprises a resin nonwoven fabric and a metal layer formed on the surface of the resin nonwoven fabric. The metal layer may be formed on at least one surface of the resin nonwoven fabric, or on both surfaces. If metal layers are formed on both surfaces, the thickness, composition, and formation method of the metal layers on both surfaces may be the same or different. Furthermore, the metal layer on one surface may be a single layer or a multi-layered layer.

[0058] From the viewpoint of providing better cushioning for the conductive laminate, the above metal layer is preferably a metal plating layer formed by electrolysis, vapor deposition (e.g., vacuum deposition), sputtering, chemical vapor deposition (CVD), metal-organic growth (MO), plating, etc.

[0059] The metals constituting the above metal layer are not particularly limited, but examples include aluminum, copper, tungsten, iron, molybdenum, nickel, titanium, silver, gold, and alloys thereof.

[0060] The fibers that make up the above-mentioned resin nonwoven fabric include natural fibers such as cotton, hemp, natural pulp, and linter pulp; regenerated fibers such as cupro and rayon; carbon fibers such as polyacrylonitrile (PAN) carbon fibers and pitch carbon fibers; nylon; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PET), and polytrimethylene terephthalate (PTT); and chemical fibers such as acrylic fibers, aramid fibers, and phenolic fibers.

[0061] The conductive nonwoven fabric B may contain conductive yarn as its constituent fibers, and may also contain nonconductive yarn. The conductive yarn is not particularly limited, but it is preferable to include nonconductive yarn and a metal layer covering at least a portion of the surface of the nonconductive yarn. Examples of the nonconductive yarn include those described and illustrated as the fibers constituting the resin nonwoven fabric above. Examples of the metal layer include those described and illustrated as the metal layer in the conductive nonwoven fabric A above.

[0062] The basis weight of the above conductive nonwoven fabric is 15 to 200 g / m². ２ Preferably, and more preferably, 30 to 50 g / m２ More preferably 35 to 45 g / m² ２ The above weight is 15 g / m². ２ The above specifications result in adequate ventilation, maintaining cushioning properties, and superior electromagnetic shielding capabilities. ２ The following conditions allow the thickness to be kept thin.

[0063] The proportion of metal in the conductive nonwoven fabric described above is preferably 10 to 50% by mass relative to the total amount of conductive nonwoven fabric (100% by mass). When the proportion is 10% by mass or more, the electromagnetic wave shielding properties are superior. When the proportion is 50% by mass or less, cushioning properties can be maintained.

[0064] The conductive nonwoven fabric may have a surface textured finish, such as a dot pattern or an embossed pattern. In this case, it is easier to maintain cushioning properties. Furthermore, by having a textured surface on one side of the conductive nonwoven fabric, when subjected to external pressure, the conductive adhesive layer adjacent to the conductive nonwoven fabric flows into the voids, making it easier to compress in the thickness direction.

[0065] From the viewpoint that the conductive substrate has electromagnetic wave shielding properties, at least one layer constituting the conductive substrate is isotropically conductive. For example, as shown in the conductive laminate 1 in Figure 1, when the conductive substrate is formed from one conductive adhesive layer, the conductive adhesive layer is isotropically conductive. Also, as shown in the conductive laminate 1 in Figures 2 to 5, when the conductive substrate is formed from two or more conductive adhesive layers, at least one conductive adhesive layer is isotropically conductive, and the other conductive adhesive layers may be anisotropically conductive or isotropically conductive. Furthermore, if the conductive substrate includes a conductive nonwoven fabric, the conductive nonwoven fabric is isotropically conductive, so the conductive adhesive layer may be anisotropically conductive or isotropically conductive.

[0066] <Conductive Adhesive Layer> The conductive adhesive layer preferably contains a conductive filler and an adhesive. The adhesive is a component that forms the matrix of the conductive adhesive layer.

[0067] The above-mentioned adhesives can be any known or commonly used ones and are not particularly limited, but examples include acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, fluorine adhesives, styrene adhesives, etc., depending on the type of base polymer. One type of adhesive may be used, or two or more types may be used.

[0068] Examples of the conductive filler mentioned above include those exemplified and described as potentially being included in the conductive adhesive layer described above. Only one type of conductive filler may be used, or two or more types may be used.

[0069] The conductive adhesive layer described above may contain other components besides those described above, as long as they do not impair the effects of the present invention. Examples of these other components include components found in known or conventional adhesive compositions. Examples of these other components include defoamers, leveling agents, thickeners, adhesives, fillers, flame retardants, colorants, fillers other than the conductive filler described above, etc. Only one of these other components may be used, or two or more may be used.

[0070] The thickness (total thickness) of the conductive adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, from the viewpoint of superior adhesion to the adherend. Furthermore, from the viewpoint of being able to make the thickness (total thickness) of the conductive adhesive layer thinner, it may be, for example, 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less.

[0071] The conductive adhesive layer described above can be manufactured by known or conventional manufacturing methods. For example, an adhesive composition for forming the conductive adhesive layer can be applied to a temporary substrate such as a release film, and if necessary, the layer can be formed by desolvation and / or partial curing.

[0072] The above adhesive composition includes, for example, each component that may be included in the conductive adhesive layer described above, as well as a solvent. Examples of solvents include toluene, acetone, methyl ethyl ketone, methanol, ethanol, propanol, and dimethylformamide. The solid content concentration of the adhesive composition is appropriately set according to the thickness of the conductive adhesive layer to be formed.

[0073] A known coating method may be used to apply the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, lip coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, direct coaters, and slot die coaters may be used.

[0074] <Conductive Laminate> The thickness of the conductive laminate of the present invention is preferably 50 to 1000 μm, more preferably 70 to 300 μm, and even more preferably 80 to 200 μm. When the thickness is within the above range, it is possible to exhibit excellent electromagnetic wave shielding properties while also providing more sufficient cushioning properties. Note that the thickness of the conductive laminate is the thickness from the surface of the conductive adhesive layer providing the adhesive surface to the surface of the conductive adhesive layer providing the adhesive surface of the conductive substrate or the other, and does not include the thickness of the release film.

[0075] The conductive laminate of the present invention can be manufactured by known or conventional methods using the conductive adhesive layer and the conductive substrate. Specifically, for example, it can be manufactured by laminating a conductive substrate and a conductive adhesive layer that have been prepared in advance.

[0076] The above-mentioned conductive laminate is preferably used inside electronic devices. Because the conductive laminate has excellent cushioning properties even when thin, it is more suitable for use inside various electronic devices (especially portable electronic devices) where space for the conductive laminate is limited. Examples of the above-mentioned portable electronic devices include mobile phones such as smartphones, cameras, game consoles, electronic organizers, tablet devices, and notebook personal computers. Among these, mobile phones such as smartphones are preferred.

[0077] The conductive laminate is preferably installed, for example, between an electronic component and the housing of an electronic device. In this case, the conductive laminate may have one end face and the other end face on either the electronic component side or the housing side. If the conductive laminate is a single-sided adhesive sheet, the conductive adhesive layer of the conductive laminate may be bonded to the electronic component side or to the housing side. The conductive adhesive layer is preferably bonded to a shielding member covering the electronic component. Furthermore, the conductive laminate may have one end face bonded to either the electronic component (or the shielding member) or the housing, and the other end face may or may not be in contact with the other electronic component (or the shielding member) or the housing. However, from the viewpoint of utilizing the cushioning properties of the conductive laminate, it is preferable that both end faces are in contact with the electronic component and the housing, respectively. By installing the conductive laminate between the electronic component and the housing, it is possible to prevent electromagnetic waves generated within the electronic component from being emitted to the outside or to prevent electromagnetic waves from entering from the outside.

[0078] Examples of the above-mentioned electronic components include IC chips, semiconductor chips (semiconductor memory, SoC, etc.), and semiconductor elements such as LEDs. Furthermore, the above-mentioned electronic components may also be components in which multiple semiconductor elements are installed, such as CPUs, batteries, and power amplifiers.

[0079] The conductive laminate is preferably arranged in a compressed state, for example, with a compression ratio (ratio of thickness after compression to thickness before compression) of 5 to 50%, preferably 10 to 45%, and more preferably 15 to 40%.

[0080] [Electronic device] An electronic device can be obtained by installing the above conductive laminate between an electronic component and a housing. The electronic device comprises an electronic component, a housing, and the above conductive laminate installed between the electronic component and the housing.

[0081] Figure 6 shows a cross-sectional view of one embodiment of the electronic device described above. In the electronic device 10 shown in Figure 6, electronic components 71 and 72 are mounted on a substrate 5 in the main body of the electronic device. The substrate 5 can be a printed circuit board (PCB), etc. The electronic components 71 and 72 are surrounded by a frame 8, and a shielding member 9 is stacked on the frame 8 so as to cover the electronic components 71 and 72. The shielding member 9 exhibits electromagnetic wave shielding properties and is made of a metal such as SUS.

[0082] In some cases, relatively thick electronic components 71 and relatively thin electronic components 72 are mounted on the same substrate 5. In such cases, in order to further reduce the thickness of the electronic device, the installation height of the shielding member 9 is set to match the height of the relatively thin electronic component 72, and a hole is made in the upper part of the shielding member 9 above the relatively thick electronic component 71. The conductive laminate 1 is then stacked on the shielding member 9 so as to cover the hole. The conductive laminate 1 covers the opening of the shielding member 9, and together with the shielding member 9, it becomes possible to effectively shield electromagnetic waves. The conductive laminate 1 is also in contact with the housing 6 and is sandwiched between the shielding member 9 and the housing 6. Because the conductive laminate 1 has cushioning properties in the thickness direction, the conductive laminate 1 is compressed in the thickness direction when sandwiched between the shielding member 9 and the housing 6. If the housing 6 is conductive, the shielding member 9 and the housing 6 become electrically connected via the conductive laminate 1 and are grounded via the housing 6.

[0083] Conventionally, metal foil or conductive nonwoven adhesive tape has been used as a material to seal the holes in the shielding member 9. However, since the thickness of metal foil and the above adhesive tape cannot be adjusted, a gap is created between the shielding member 9 and the housing 6. While conductive sponge or gasket could be used as a material to seal the holes, their inclusion would inevitably increase the thickness, making them unsuitable for use when the space between the shielding member 9 and the housing 6 is narrow. In contrast, the conductive laminate of the present invention can be designed to be either thick or thin. Therefore, the conductive laminate can change thickness due to external pressure, regardless of whether it is thick or thin, and can exhibit excellent conformability to the substrate and superior electromagnetic shielding even when used in the limited space within electronic equipment.

[0084] The following describes variations of the invention according to the present invention. [Note 1] A conductive laminate comprising a conductive substrate containing a conductive adhesive layer and a conductive adhesive layer laminated on at least one surface of the conductive substrate, wherein the conductive adhesive layer has a void between adjacent layers. [Note 2] The conductive laminate according to Note 1, wherein the conductive substrate includes a conductive nonwoven fabric. [Note 3] The conductive laminate according to Note 1 or 2, wherein the conductive adhesive layer has an uneven surface, and the recesses of the uneven surface correspond to the void. [Note 4] The conductive laminate according to any one of Notes 1 to 3, wherein the conductive adhesive layer and the conductive adhesive layer are laminated adjacent to each other, and the void is between the conductive adhesive layer and the conductive adhesive layer. [Note 5] The conductive laminate according to any one of Notes 1 to 4, wherein the conductive substrate contains at least two layers in total of conductive nonwoven fabric and / or conductive adhesive layers, at least one of the two layers is a conductive adhesive layer, and the void is between the two layers. [Note 6] A conductive laminate according to any one of Notes 1 to 5, having a configuration in which the conductive substrate, the conductive adhesive layer, the conductive substrate, and the conductive adhesive layer are laminated in this order. [Note 7] A conductive laminate according to Note 6, having a configuration in which the conductive adhesive layer, the conductive adhesive layer, the conductive adhesive layer, and the conductive adhesive layer are laminated in this order, wherein the conductive adhesive layer located between two of the conductive adhesive layers is embedded in the conductive adhesive layer. [Note 8] A conductive laminate according to any one of Notes 1 to 7, used by being stacked so as to block the holes of a shielding member that covers an electronic component mounted on a substrate. [Note 9] An electronic device comprising a substrate, an electronic component mounted on the substrate, a shielding member that covers the electronic component and has a hole above at least one electronic component, and a conductive laminate according to any one of Notes 1 to 8 stacked on the shielding member so as to block the holes of the shielding member. [Note 10] The electronic device according to Note 9, further comprising a housing that sandwiches the conductive laminate between the shielding member.

[0085] 1 Conductive laminate 2 Conductive substrate 21, 211, 212 Conductive adhesive layer 3, 31, 32, 33 Conductive adhesive layer 41, 42 Release film 5 Substrate 6 Housing 71, 72 Electronic component 8 Frame 9 Shielding member 10 Electronic equipment A, A1, A2 Gap

Claims

1. A conductive laminate comprising a conductive substrate containing a conductive adhesive layer, and a conductive adhesive layer laminated on at least one surface of the conductive substrate, wherein the conductive adhesive layer has voids between adjacent layers.

2. The conductive laminate according to claim 1, wherein the conductive substrate includes a conductive nonwoven fabric.

3. The conductive laminate according to claim 1, wherein the conductive adhesive layer has an uneven surface, and the recesses of the uneven surface correspond to the voids.

4. The conductive laminate according to claim 1, wherein the conductive adhesive layer and the conductive adhesive layer are laminated adjacent to each other, and the void is between the conductive adhesive layer and the conductive adhesive layer.

5. The conductive laminate according to claim 1, wherein the conductive substrate comprises at least two layers in total of a conductive nonwoven fabric and / or a conductive adhesive layer, at least one of the two layers being a conductive adhesive layer, and the void between the two layers.

6. The conductive laminate according to claim 1, having a configuration in which the conductive substrate, the conductive adhesive layer, the conductive substrate, and the conductive adhesive layer are laminated in this order.

7. The conductive laminate according to claim 6, having a configuration in which the conductive adhesive layer, the conductive adhesive layer, the conductive adhesive layer, and the conductive adhesive layer are laminated in this order, wherein the conductive adhesive layer located between the two conductive adhesive layers is embedded in the conductive adhesive layer.

8. A conductive laminate according to any one of claims 1 to 7, which is used by stacking it so as to cover the holes of a shielding member that covers an electronic component mounted on a substrate.

9. An electronic device comprising a substrate, electronic components mounted on the substrate, a shielding member covering the electronic components and having a hole in the upper part of at least one of the electronic components, and a conductive laminate according to any one of claims 1 to 7, which is stacked on the shielding member so as to cover the hole in the shielding member.

10. The electronic device according to claim 9, further comprising a housing that sandwiches the conductive laminate between the shielding member.

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