Laminate and electronic device using the same

Abstract

To provide a laminate that has wiring on a support substrate side and has excellent bending resistance of a conductive layer (wiring).SOLUTION: A laminate comprising a resin layer (A) and a conductive layer (B), wherein the resin layer (A) is elastic, the conductive layer (B) is embedded in the resin layer (A) and exposed on one of surfaces of the resin layer (A).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminate and an electronic device using the same. [Background technology]

[0002] In the electronics field, there is an increasing demand for devices and conductive materials that are easy to wear and conform to shapes, especially for devices and devices used in various interfaces such as sensors, displays, and artificial skin for robots. There is a growing demand for flexible devices that can be placed on curved or uneven surfaces and can be freely deformed depending on the application.

[0003] Stretchable substrates for use in such flexible devices have already been reported, but there is a risk that wiring on the stretchable substrate may break when the substrate is stretched or bent.

[0004] In view of this, in the case of stretchable substrates, stretchable wiring using a conductive composition containing a conductive material and an elastomer has been reported (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-143763 A Summary of the Invention [Problem to be solved by the invention]

[0006] This is a circuit board having elasticity and flexibility, as disclosed in Patent Document 1. However, as described in these documents, when forming wiring on a substrate using conventional techniques, a resin layer that serves as the substrate is usually formed on a supporting base material, and then wiring is formed on the resin layer.

[0007] However, when a supporting substrate is used, wiring can only be formed on one side of the substrate, and wiring cannot be formed on the opposite side (the side where the supporting substrate is present), which limits the number of laminated substrates. Furthermore, in the circuit substrate described in the above document, since the wiring is formed on the surface of the substrate, there is a problem that if the wiring is not flexible, bending resistance is not obtained and the wiring is easily broken. On the other hand, when a flexible conductive paste containing an elastomer is used as the wiring, the resistance value may be high, or the solder adhesion may be insufficient due to the influence of the elastomer when mounting electronic components on the wiring.

[0008] The present invention has been made in view of the above circumstances, and has a main object to provide a laminate having wiring on the supporting substrate side and having excellent bending resistance of the conductive layer (wiring). [Means for solving the problem]

[0009] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by the following configuration, and have completed the present invention through further investigations based on this finding.

[0010] That is, a laminate according to one aspect of the present invention is a laminate comprising a resin layer (A) and a conductive layer (B), characterized in that the resin layer (A) is elastic, and the conductive layer (B) is embedded in the resin layer (A) and is exposed on either one of the surfaces of the resin layer (A). Effect of the Invention

[0011] According to the present invention, it is possible to provide a laminate having wiring on the supporting substrate side and having excellent bending resistance of the conductive layer (wiring). [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a schematic cross-sectional view of a laminate according to another embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a laminate according to still another embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view of a laminate in which conductive layers are electrically connected to each other, which is still another embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view of a laminate having a multi-layer structure, which is still another embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view of a laminate provided with a supporting substrate, which is still another embodiment of the present invention. [Figure 7] 7A to 7F are schematic cross-sectional views showing a manufacturing process of a laminate according to one embodiment of the present invention. [Figure 8] 8A to 8D are schematic cross-sectional views showing a manufacturing process of the laminate of Example 1. [Figure 9] 9A to 9D are schematic cross-sectional views showing a manufacturing process of the laminate of Example 2. [Figure 10] 10A to 10E are schematic cross-sectional views showing a manufacturing process of the laminate of Example 3. [Figure 11] 11A to 11E are schematic cross-sectional views showing a manufacturing process of the laminate of Example 4. [Figure 12] 12A to 12D are schematic cross-sectional views showing a manufacturing process of the laminate of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, etc. However, the embodiment described below is merely one of various embodiments of the present invention. The following embodiment can be modified in various ways depending on the design as long as the object of the present invention can be achieved.

[0014] (Laminate of First Embodiment) First, the configuration of the laminate of the first embodiment will be specifically described.

[0015] 1, the laminate of the first embodiment includes a resin layer (A) 1 and a conductive layer (B) 2. The resin layer (A) 1 is stretchable. The conductive layer (B) 2 is embedded in the resin layer (A) 1 and exposed on one of the surfaces of the resin layer (A) 1.

[0016] The resin layer (A) 1 being "stretchable" means that it is capable of stretching, and the stretchable resin layer (A) of this embodiment preferably satisfies the tensile modulus and / or breaking elongation shown below. Specifically, the tensile stress of the resin layer (A) 1 at 50% elongation is preferably 0.5 MPa or more and 10 MPa or less. Alternatively, the breaking elongation is preferably 50% or more and 700% or less. In addition, it is more preferable that it is elastically deformable.

[0017] With this configuration, the laminate has flexibility and the conductive layer (B) has bending resistance. In addition, in a circuit board or the like using the laminate of this embodiment, wiring or circuits can be formed on the support substrate (release film) side of the insulating layer composed of the resin layer (A). Therefore, the laminate of this embodiment can be suitably used in applications such as stretchable electronic devices.

[0018] In the present embodiment, the "elongation at break" refers to the elongation rate until breakage, and is an index showing the flexibility of the resin layer (A). The elongation at break is more preferably 100% or more and 500% or less.

[0019] A laminate having a resin layer (A) having a breaking elongation within the above-mentioned range has high conformability when deformed into any shape, and therefore, when the laminate of this embodiment is used as a stretchable circuit board material, it is considered possible to obtain a circuit board that has excellent conformability to clothing, is resistant to breakage, and has excellent stretchability.

[0020] The breaking elongation in this embodiment is a value measured by the following method: First, the cured product of the resin composition constituting the resin layer (A) is cut into a dumbbell No. 6 (JIS K 6251, 2017) and attached to a universal testing machine (AGS-X manufactured by Shimadzu Corporation). Then, a test is performed at room temperature (25°C) and a tensile speed of 25 mm / min, and the elongation at which the cured product breaks is measured with the testing machine and defined as the "breaking elongation."

[0021] The tensile stress at 50% elongation of the resin layer (A) refers to the tensile stress when the elongation rate becomes 50% in the above-mentioned tensile test, and together with the above-mentioned breaking elongation rate, it is an index showing the flexibility of the resin layer (A). Since it is within the above-mentioned range, there is an advantage that the wiring and component mounting part are less likely to be broken when the laminate of this embodiment is used as a stretchable circuit board material, because the followability when deforming into any shape is high. A more preferable range of the tensile stress is 1.0 MPa or more and 5 MPa or less.

[0022] In this embodiment, the tensile stress is a value measured by the following method: As in the measurement of the breaking elongation rate described above, the cured resin composition constituting the resin layer (A) is cut into a dumbbell No. 6 (JIS K 6251, 2017) and attached to a universal testing machine (AGS-X manufactured by Shimadzu Corporation). Then, a test is performed at room temperature (25°C) and a tensile speed of 25 mm / min, and the stress value when the tensile elongation rate reaches 50% is calculated. Stress (σ) = F / (d·l) (F is the test force, d is the film thickness, and l is the width of the test piece)

[0023] Hereinafter, each component of the laminate of this embodiment will be described.

[0024] ·Resin layer (A) The resin component in the resin composition used for the resin layer (A) of this embodiment is not particularly limited as long as the cured product of the resin composition has elasticity. For example, it is preferable that the resin component is such that the tensile stress at 50% elongation in the cured product is 0.5 MPa or more and 10 MPa or less, and / or the elongation at break is 50% or more and 700% or less.

[0025] The resin layer (A) of this embodiment is preferably composed of a curable resin composition or a cured product of a thermoplastic resin composition. Examples of the resin contained in the curable resin composition or the thermoplastic resin composition include a thermoplastic resin and a thermosetting resin. Examples of the thermoplastic resin include, for example, a urethane resin, various rubbers, an acrylic resin, an olefin resin, an ethylene propylene diene rubber, an isoprene rubber, a butadiene rubber, and a chloroprene rubber. In this embodiment, it is preferable to use a curable resin composition containing a thermosetting resin, particularly from the viewpoint of excellent adhesion and heat resistance, and of being able to impart functions such as chemical resistance, and it is preferable to use at least one selected from epoxy resins, urethane resins, silicone resins, polyrotaxane resins, isocyanate resins, polyol resins, styrene-based elastomer resins, and acrylic acid ester copolymer resins as the thermosetting resin, and it is more preferable to use epoxy resins, polyrotaxane resins, styrene-based elastomer resins, etc. among them. These resins may be used alone or in combination of two or more.

[0026] Furthermore, the resin composition may contain various additives such as a curing agent, a curing accelerator, a filler, an antioxidant, a leveling agent, a pigment, a dye, etc., within a range that does not impair the effects of the present invention. In particular, when a styrene-based elastomer resin is used, it is preferable to add an organic peroxide as an additive to the resin composition. This forms a crosslinked structure and provides heat resistance, so that deformation of the resin layer or the conductive layer in a high-heat environment can be suppressed. In this case, as the organic peroxide, any organic peroxide that can be used as a radical polymerization initiator can be used without any particular limitation.

[0027] In the laminate of this embodiment, the thickness of the resin layer (A) can be appropriately set depending on the application of the laminate, and is, for example, about 0.01 mm or more and 1 mm or less. Furthermore, it is preferably 0.02 mm or more and 0.2 mm or less. If the thickness is thinner than this, the handling property becomes poor and the strength of the resin layer also decreases. On the other hand, if it is thicker than this, air bubbles are easily generated, the resin layer becomes hard, and the flexibility as a device decreases. It is also disadvantageous when conducting electricity across the resin layer.

[0028] ·Conductive layer (B) The conductive layer (B) 2 embedded in the resin layer (A) may be elastic or non-elastic, but is preferably made of an electrically conductive material containing at least one selected from an electrically conductive resin composition or a metal. The conductive layer (B) 2 may be a patterned circuit as shown in FIG. 1.

[0029] The conductive layer (B) 2 embedded in the resin layer (A) is partially exposed on one surface of the resin layer (A) 1. For example, in FIG. 1, the surface is exposed from the bottom surface of the resin layer (A). The portion exposed from the resin layer (A) may be only the surface of the conductive layer (B), or the surface of the conductive layer (B) and also a part of the side surface may be exposed. This is true not only for the first embodiment, but also for other embodiments described later.

[0030] In this embodiment, the elastic conductive material may be, for example, a conductive resin composition (conductive paste). The conductive resin composition that may be used in this embodiment may be, for example, a conductive resin composition containing a binder resin made of a thermosetting resin and / or a thermoplastic resin and conductive particles. Examples of the thermosetting resin include silicone resin, urethane resin, epoxy resin, acrylic resin, and fluororubber. Examples of the thermoplastic resin include urethane resin, acrylic resin, olefin resin, ethylene propylene diene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, and polyester resin. In particular, from the viewpoint of adhesion to the adhesive layer and the conductive layer, it is preferable to use urethane resin, epoxy resin, acrylic resin, acrylic resin, olefin resin, ethylene propylene diene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, and polyester resin, and acrylic resin, epoxy resin, urethane resin, polyester resin, and nitrile rubber are more preferable.

[0031] Specific examples of the conductive particles include silver, silver-coated copper (including a configuration in which part of the copper surface is coated with silver), copper, gold, carbon particles, carbon nanotubes, conductive polymers, tin, bismuth, indium, gallium, nickel, aluminum, etc., and particles composed of alloys of these metals.

[0032] As described above, examples of the conductive resin composition of the present embodiment include silver pastes and silver inks obtained by combining elastic epoxy resins, acrylic resins, urethane resins, silicone resins, fluororesins, styrene-butadiene copolymer resins, polyester resins, and various rubbers with silver powder, silver flakes, and the like.

[0033] Examples of non-stretchable conductive materials include metals, and more specifically, copper (including those surface-treated with gold or the like), aluminum, nickel, and the like.

[0034] Alternatively, the conductive layer (B) may be composed of a sintered body of metal particles, etc. A sintered body is a body in which fine particles of silver, copper, gold, etc. are heated at an appropriate firing temperature to melt the particles or the particle surfaces into a solid solution, and is obtained by printing, heating, drying, and firing a metal particle dispersion ink in which the fine particles are dispersed in water or an organic solvent.

[0035] In a preferred embodiment, the conductive layer (B) is non-elastic. When using an elastic conductive resin composition as described above, the resistance value may be high, and the solder adhesion may be insufficient due to the influence of the resin component contained in the composition. Therefore, from the viewpoint of suppressing the resistance value of the wiring / circuit and solder adhesion when mounting electronic components with solder, it is preferable that the conductive layer (B) is non-elastic. Usually, when the resin layer (A) is elastic and the conductive layer (B) is non-elastic, the bending resistance of the conductive layer (B) is deteriorated, and the wiring / circuit may break. However, in the laminate of this embodiment, since the conductive layer (B) is embedded in the resin layer (A), such breakage can be suppressed.

[0036] The thickness of the substrate and the conductive layer (B) in this embodiment is not particularly limited, but is usually about 0.01 μm or more and 50 μm or less, and more preferably about 1 μm or more and 35 μm or less.

[0037] (Laminate of Second Embodiment) 2, the laminate of the second embodiment includes, in addition to the configuration of the laminate of the first embodiment, a second conductive layer (B') 2' that is embedded in the resin layer (A) 1 like the conductive layer (B) 2 and is exposed on the surface opposite to the surface on which the conductive layer (B) 2 is exposed in the resin layer (A) 1. The second conductive layer (B') 2' may also be a patterned circuit as shown in FIG.

[0038] The second conductive layer (B') 2' of the second embodiment may be a non-elastic conductive layer similar to the conductive layer (B) described in the first embodiment, or may be an elastic conductive layer. The second conductive layer (B') 2' and the conductive layer (B) 2 may have the same configuration or may be different. That is, for example, when the conductive layer (B) is non-elastic, the second conductive layer (B') 2' may be a similarly non-elastic conductive layer, or may be a different elastic conductive layer. In a preferred embodiment, the second conductive layer (B') 2' of the second embodiment is non-elastic, so that the laminate of the second embodiment has the same advantages as the laminate of the first embodiment in which the conductive layer (B) is non-elastic.

[0039] (Laminate of Third Embodiment) The laminate of the third embodiment further includes, in addition to the configuration of the laminate of the first embodiment, a second conductive layer (B') 3 formed on the surface of the resin layer (A) opposite to the surface on which the conductive layer (B) is exposed, as shown in Fig. 3. The second conductive layer (B') 3 may also be a patterned circuit as shown in Fig. 3.

[0040] The second conductive layer (B') 3 in the laminate of the third embodiment is not embedded in the resin layer (A) but is formed on the surface of the resin layer (A), unlike the second conductive layer (B') in the second embodiment.

[0041] The second conductive layer (B') 3 in the third embodiment may be a non-elastic conductive layer similar to the conductive layer (B) described in the first embodiment, or may be an elastic conductive layer. The second conductive layer (B') 3 and the conductive layer (B) 2 may have the same configuration or may be different. That is, for example, when the conductive layer (B) is non-elastic, the second conductive layer (B') 3 may be a similarly non-elastic conductive layer, or may be a different elastic conductive layer. In a preferred embodiment, the second conductive layer (B') 3 in the third embodiment is formed on the resin layer (A), and therefore is preferably elastic. This is because the second conductive layer (B') 3 exposed on the resin layer (A) can have bending resistance.

[0042] (Laminate of Fourth Embodiment) The laminate of the fourth embodiment is characterized in that, in the laminate having the second conductive layer (B') as in the second or third embodiment, the conductive layer (B) and the second conductive layer (B') are electrically connected to each other. For example, FIG. 4 shows the laminate of the third embodiment in which the conductive layer (B) 2 and the second conductive layer (B') 3 are electrically connected to each other at the location indicated by C. Note that, although FIG. 4 shows the electrical connection in the laminate of the third embodiment, the conductive layer (B) 2 and the second conductive layer (B') 2' can also be electrically connected to each other in the laminate of the second embodiment.

[0043] (Laminate of Fifth Embodiment) As shown in Fig. 5, the laminate of the fifth embodiment has, in addition to the configuration of the laminate of the first embodiment, a second resin layer (A') 4 on the resin layer (A) 1, and a second conductive layer (B') 2' is embedded in the second resin layer (A') 4. Furthermore, the laminate further has a third conductive layer (B'') 3 formed on the surface of the second resin layer (A') 4 opposite to the surface in which the conductive layer (B') 2' is embedded. This third conductive layer (B'') 3 may also be a patterned circuit as shown in Fig. 5.

[0044] The second resin layer (A') 4 is preferably provided on the surface of the resin layer (A) 1 opposite to the surface in which the conductive layer (B) is embedded.

[0045] The second resin layer (A') 4 may be made of the same material as the resin layer (A) 1, or may be made of a cured product of a different resin composition. It may be stretchable or non-stretchable, or may be a mixture of stretchable and non-stretchable resin layers. It is preferable that the second resin layer (A') 4 has the same stretchability as the resin layer (A) 1, but for example, the portion on which electronic components are mounted may be made of a non-stretchable resin layer.

[0046] When the second resin layer (A') 4 is stretchable, it may be composed of a cured product of a resin composition similar to that of the resin layer (A) 1 described in the first embodiment. On the other hand, when the second resin layer (A') 4 is non-stretchable, a resin that can be used as an insulating layer for a so-called rigid substrate can be used as the main component. Specifically, examples of the resin include polyimide, polyetherimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyphenylene ether, vinylon, cellulose, cellulose acetate, polyolefin, polystyrene, polyacrylate, triacetate, nylon, aramid, polyethersulfone, polyphenylsulfide, polyetheretherketone, polyacetal, norbornene resin, fluororesin, polymethylpentene resin, styrene-butadiene-acrylonitrile copolymer, ethylene-vinyl acetate copolymer, styrene-acrylonitrile copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, tetrafluoroethylene-ethylene copolymer, vinylidene fluoride, etc. The above-mentioned resins may be laminated with fibers, etc.

[0047] The second conductive layer (B') 2' may be a non-elastic conductive layer similar to the conductive layer (B) described in the first embodiment, or may be an elastic conductive layer. The second conductive layer (B') 2' and the conductive layer (B) 2 may have the same configuration or may be different. That is, for example, when the conductive layer (B) is non-elastic, the second conductive layer (B') 2' may be a similarly non-elastic conductive layer, or may be a different elastic conductive layer. In a preferred embodiment, the second conductive layer (B') 2' of the second embodiment is non-elastic, so that the laminate of the second embodiment has the same advantages as the laminate of the first embodiment in which the conductive layer (B) is non-elastic.

[0048] The third conductive layer (B'') 3 may be a non-elastic conductive layer similar to the conductive layer (B) described in the first embodiment, or may be an elastic conductive layer. The second conductive layer (B') 3 and the conductive layer (B) 2 may have the same configuration or may be different. That is, for example, when the conductive layer (B) is non-elastic, the second conductive layer (B') 3 may be a similarly non-elastic conductive layer, or may be a different elastic conductive layer. In a preferred embodiment, the second conductive layer (B') 3 in the fifth embodiment is formed on the second resin layer (A') 4, and therefore is preferably elastic. This is because the second conductive layer (B') 3 exposed on the resin layer (A) can have bending resistance.

[0049] It is also preferable that the second conductive layer (B') 2' and / or the third conductive layer (B'') 3 are appropriately selected depending on the material constituting the second resin layer (A') 4. In other words, when the second resin layer (A') 4 is made of a material having non-elasticity, it is preferable that the second conductive layer (B') 2' and the third conductive layer (B'') 3 have elasticity. On the other hand, when the second resin layer (A') 4 is made of a material having elasticity, at least the conductive layer (B') 2' may be non-elastic. However, since the third conductive layer (B'') 3 is exposed on the resin layer in any case, it is preferable that it is elastic.

[0050] (Laminate of Sixth Embodiment) The laminate of the sixth embodiment further includes a supporting substrate (C) in addition to the configuration of the laminate of the first to fifth embodiments. Fig. 6 shows, as an example, a laminate including a supporting substrate (C) 5 in the laminate of the first embodiment.

[0051] Examples of the supporting substrate (C) that can be used include, without particular limitation, films used as release films, and specific examples include electrically insulating films such as polyimide films, polyamide films, PET (polyethylene terephthalate) films, PEN (polyethylene naphthalate) films, polyester films, polyparabanic acid films, polyether ether ketone films, polyphenylene sulfide films, aramid films, polycarbonate films, and polyarylate films.

[0052] Although not shown, the laminate of this embodiment may further include a protective layer (D) on the opposite side of the supporting substrate (C) in addition to the supporting substrate (C). As the protective layer (D), any film generally used as a cover film can be used without particular limitation, and examples thereof include electrically insulating films such as PEN (polyethylene naphthalate) film, polyimide film, polyamide film, PET (polyethylene terephthalate) film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, aramid film, polycarbonate film, polyarylate film, polyethylene film, and polypropylene film.

[0053] The laminate of the present embodiment described above can be used for various purposes, but for example, it can be suitably used as a material for electronic devices, particularly circuit boards.

[0054] (Method of manufacturing laminate) Next, a method for producing the laminate of the present embodiment will be described. The method for producing the laminate of the present embodiment is not particularly limited as long as it is a method for obtaining the laminate as described above.

[0055] For example, FIG. 7 is a diagram showing an example of a method for producing a laminate of this embodiment. First, as shown in FIG. 7A, a conductive layer (B) 2 is formed on a supporting substrate (C) 5. The conductive layer (B) 2 may be a circuit patterned as shown in FIG. 7A. The method for forming the circuit is not particularly limited, and for example, a circuit (wiring) can be formed by subjecting a conductive layer (B) made of a metal foil provided on a supporting substrate (C) 5 to etching processing or the like. As a method for forming a circuit, in addition to the above-mentioned methods, for example, circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP) can be mentioned.

[0056] Alternatively, a method for forming a circuit using a conductive composition etc. can be performed, for example, by a printing method etc. Specifically, when the conductive layer (B) 2 is composed of a paste of a conductive resin composition, a circuit having a desired pattern can be formed by printing and applying it onto the supporting base material (C) 5 by a printing method such as screen printing, inkjet printing, gravure printing, offset printing, etc.

[0057] When the conductive layer (B) is composed of a sintered body of metal particles, for example, an ink containing the above-mentioned sintered body of metal particles (metal particle dispersion ink) is printed by inkjet or the like, and then heated, dried, and baked to form a circuit pattern on the supporting substrate (C) 5.

[0058] In addition to the above, the circuit pattern of the conductive layer (B) 2 can be formed by electrolytic or electroless plating, or by vapor deposition of a metal.

[0059] Next, as shown in FIG. 7B, a resin varnish 1′ of the resin composition constituting the resin layer (A) is applied to a desired thickness onto the supporting substrate (C) 5 on which the circuit pattern of the conductive layer (B) 2 has been formed. coatingExamples of the application method include a bar coater, a comma coater, a die coater, a roll coater, a gravure coater, etc. The material used to form the resin layer (A) is not limited to the resin varnish, and a semi-cured product or a dry film of the resin composition may be attached to the supporting substrate (C) 5 on which the circuit pattern of the conductive layer (B) 2 is formed.

[0060] The resin varnish is prepared, for example, as follows. First, each component that can be dissolved in an organic solvent, such as a resin component (thermosetting resin or various additives), is put into an organic solvent and dissolved. At this time, heating may be performed as necessary. Then, a component that is not soluble in an organic solvent (for example, an inorganic filler, etc.) is added as necessary, and the mixture is dispersed until a predetermined dispersion state is reached using a disperser, a ball mill, a bead mill, a planetary mixer, a roll mill, etc., to prepare a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves the resin components and additives and does not inhibit the curing reaction. Specific examples include toluene, methyl ethyl ketone, cyclohexanone, and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more. In addition, a part or all of the solvent may be replaced with a reactive diluent. Specific examples of reactive diluents include styrene, butyl acrylate, butyl methacrylate, butyl glycidyl ether, and 1,2-dodecene.

[0061] Thereafter, as shown in FIG. 7C, the resin layer 1' that has been applied and dried if it contains a solvent is cured by heating and pressing under desired conditions, for example, at a pressure of about 0.1 MPa to 20 MPa and a temperature of 50 to 220°C for 1 minute to 2 days to form a resin layer (A) 1. At this stage, a laminate with the supporting substrate (C) of the sixth embodiment is obtained. Furthermore, if the supporting substrate (C) is peeled off from the laminate, the laminate of the first embodiment is obtained. The pressure is preferably 0.3 MPa to 10 MPa, more preferably 1.0 MPa to 5 MPa, from the viewpoint of burying the conductive layer and suppressing the resin flow. The temperature is preferably 80°C to 220°C, more preferably 130°C to 200°C, from the viewpoint of increasing the fluidity of the resin, burying the conductive layer, and promoting curing. Furthermore, it is preferable to evacuate the resin when heating and pressing it. This can suppress oxidation of the conductive layer.

[0062] In addition, when the resin layer before curing exhibits fluidity, the resin layer (A) 1 can be formed by curing for 1 minute to 2 days at a temperature of 0 to 220° C. without applying pressure. The temperature is more preferably 20° C. or more and 220° C. or less from the viewpoint of promoting curing.

[0063] When a multi-layer laminate is to be produced, a second conductive layer (B') 2' may be formed on the resin layer (A) 1 of the laminate obtained above, as shown in Fig. 7D. The second conductive layer (B') 2' may be formed in the same manner as the conductive layer (B) 2. At this stage, the support base material (C) 5 may be peeled off to obtain the laminate of the third embodiment.

[0064] Next, a second resin layer (A') 4 may be further formed on the resin layer (A) 1 on which the circuit pattern of the second conductive layer (B') 2' is formed. In this case, the second conductive layer (B') 2' is embedded in the second resin layer (A') 4. The second resin layer (A') 4 can be formed in the same manner as the resin layer (A) 1.

[0065] Furthermore, after forming the second resin layer (A') 4, the third conductive layer (B'') 3 can be formed thereon. The third conductive layer (B'') 3 can be formed in the same manner as the conductive layer (B) 2.

[0066] Then, by peeling off the supporting base material (C) 5 from the resulting multi-layer laminate, the laminate of the fifth embodiment can be obtained as shown in FIG. 7E.

[0067] Furthermore, in the obtained multi-layer laminate, the conductive layers can be electrically connected to each other as shown in Fig. 7F. In Fig. 7F, the conductive layer (B) 2 and the second conductive layer (B') 2' are electrically connected to each other, but the electrical connection can be established between any desired conductive layers. The means for electrical connection is not particularly limited, and electrical connection can be established by, for example, crimping, riveting, through-hole plating, blind via holes, connection posts filled with conductive paste, anisotropic conductive film (ACF), conductive adhesive, connection by wiring, connection by electronic components, or the like.

[0068] (Electronic Devices) This embodiment also includes an electronic device in which an electronic component is further mounted on the laminate.

[0069] Electronic components that can be mounted in this embodiment are not particularly limited, but examples include resistors, transistors, signal transmission elements, light-emitting elements, solar power generation elements, diodes, switching elements, capacitors, coils, liquid crystal, wireless modules such as Bluetooth (registered trademark), various sensors such as acceleration sensors, humidity sensors, and temperature sensors, and chip components used in RFID, etc.

[0070] The electronic components can be mounted, for example, by a mounting method using a conductive adhesive or bonding agent, a mounting method using solder and reflow, etc. Also, instead of soldering, it is possible to print elements on the resin layer (A) or the conductive layer (B) of the laminate.

[0071] As described above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

[0072] The laminate according to the first aspect of the present invention is a laminate comprising a resin layer (A) and a conductive layer (B), characterized in that the resin layer (A) is elastic, and the conductive layer (B) is embedded in the resin layer (A) and is exposed on either one of the surfaces of the resin layer (A).

[0073] The laminate according to the second aspect is the laminate according to the first aspect, wherein the conductive layer (B) contains silver or copper.

[0074] The laminate according to a third aspect is the laminate according to the first aspect, characterized in that the conductive layer (B) is non-stretchable.

[0075] The laminate according to a fourth aspect is the laminate according to the first aspect, characterized in that the resin layer (A) has a tensile stress of 0.5 MPa or more and 100 MPa or less at 50% elongation.

[0076] The laminate according to a fifth aspect is characterized in that in the laminate of the first aspect, the resin layer (A) has a breaking elongation of 50% or more and 700% or less.

[0077] The laminate of the sixth aspect is the laminate of the first aspect, further comprising a second conductive layer (B') that is embedded in the resin layer (A) and exposed on the surface of the resin layer (A) opposite to the surface on which the conductive layer (B) is exposed.

[0078] The laminate according to a seventh aspect is the laminate according to the sixth aspect, characterized in that the second conductive layer (B') is non-stretchable.

[0079] The laminate of the eighth aspect is the laminate of the first aspect, further comprising a second conductive layer (B') formed on the surface of the resin layer (A) opposite to the surface on which the conductive layer (B) is exposed.

[0080] The laminate according to a ninth aspect is the laminate according to the eighth aspect, characterized in that the second conductive layer (B') is stretchable.

[0081] The laminate according to a tenth aspect is the laminate according to the eighth aspect, characterized in that at least a part of the conductive layer (B) and at least a part of the second conductive layer (B') are electrically connected to each other.

[0082] The laminate of the eleventh aspect is characterized in that, in the laminate of the first aspect, a second resin layer (A') is further provided on the resin layer (A), a second conductive layer (B') is embedded in the second resin layer (A'), and a third conductive layer (B'') is formed on the surface of the second resin layer (A') opposite to the surface in which the conductive layer (B') is embedded.

[0083] The laminate according to a twelfth aspect is the laminate according to the first aspect, further comprising a supporting substrate (C).

[0084] The laminate according to a thirteenth aspect is the laminate according to the first aspect, further comprising a protective layer (D).

[0085] An electronic device according to a fourteenth aspect includes the laminate according to any one of the first to thirteenth aspects and an electronic component.

[0086] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0087] First, a resin composition (varnish) for forming a resin layer was prepared.

[0088] (Production Example 1) 100 parts by mass of polyrotaxane "SH3400P" (manufactured by ASM Co., Ltd.), 90 parts by mass of epoxy resin "JER1003" (manufactured by Mitsubishi Chemical Co., Ltd.), 2 parts by mass of monofunctional acid anhydride "YH-307" (manufactured by Mitsubishi Chemical Co., Ltd.) as a curing agent, and 1 part by mass of imidazole curing accelerator "2E4MZ" (manufactured by Shikoku Kasei Kogyo Co., Ltd.) were dissolved in a solvent (MEK / toluene (mass ratio 4 / 6)) while stirring to prepare a resin varnish with a concentration of 50% by mass. After leaving to stand and degassing, the resin varnish was applied to a release-treated PET film ("SP-PET O1" manufactured by Mitsui Chemicals Tohcello Co., Ltd.) that was to become a protective layer, using a bar coater. Then, it was dried in an oven at 80 ° C. for 10 minutes to obtain a dried film A consisting of a dried product of the resin composition. The dried film A was then heated in an oven at 160° C. for 5 minutes to obtain a semi-cured film (thickness: 100 μm) made of a semi-cured product of the resin composition.

[0089] (Production Example 2) A resin varnish was prepared by dissolving 99 parts by weight of a styrene-isoprene-styrene (SIS) block copolymer, "Hybler (registered trademark) 5125" (manufactured by Kuraray Co., Ltd.), and 1 part by weight of (1,3-bis(butylperoxyisopropyl)benzene, "Perbutyl (registered trademark) P" (manufactured by NOF Corporation), as an organic peroxide, in 200 parts by weight of toluene. This was then applied to a release-treated PEN film "J0" (manufactured by Nippa Co., Ltd.), which would serve as a protective layer, and dried at 80°C for 10 minutes and then at 110°C for 10 minutes to prepare a dry film (thickness 100 μm).

[0090] <Manufacture of Laminate> Example 1 The manufacturing process of the laminate of Example 1 is shown in FIG. 8. First, as shown in FIG. 8A, a circuit pattern was screen-printed using copper ink "LF360" (manufactured by Copprint) on a 50 μm release-treated polyimide film "J0" (manufactured by Nippa Corporation) as a supporting substrate 5, and dried at 90° C. for 2 minutes to form a conductive layer 2. The conductive layer had a line width of 1 mm, a length of 10 cm, and a thickness of 20 μm. Next, as shown in FIG. 8B, a semi-cured film 1' (with protective layer 6) of the resin composition of Production Example 1 was laminated on the polyimide film 5 on which the conductive layer 2 was formed at 40° C. and 0.3 MPa using a vacuum laminator for 60 seconds. Then, the protective layer 6 (PEN film) was peeled off (FIG. 8C). Next, the semi-cured film 1' was cured by heating in an oven at 160° C. for 1 hour to form a resin layer 1, and a laminate of Example 1 (with supporting substrate 5) was obtained.

[0091] Example 2 The manufacturing process of the laminate of Example 2 is shown in FIG. 9. First, as shown in FIG. 9A, a circuit pattern was screen-printed using copper ink "LF360" (manufactured by Copprint) on a 50 μm release-treated polyimide film "J0" (manufactured by Nippa Corporation) as a supporting substrate 5, and dried at 90° C. for 2 minutes to form a conductive layer 2. The conductive layer had a line width of 1 mm, a length of 10 cm, and a thickness of 20 μm. Next, as shown in FIG. 9B, the dry film 1' (with protective layer 6) of Manufacturing Example 2 was laminated at 80° C. and 0.3 MPa for 60 seconds using a vacuum laminator. Thereafter, the dry film 1' was cured by hot pressing at 180° C. for 30 minutes at 4 MPa to form a resin layer 1 (FIG. 9C). Then, the protective layer 6 (PEN film) was peeled off to obtain a laminate of Example 2 (with supporting substrate 5) (FIG. 9D).

[0092] Example 3 The manufacturing process of the laminate of Example 3 is shown in FIG. 10. First, as shown in FIG. 10A, a circuit pattern was screen-printed using copper ink "LF360" (manufactured by Copprint) on a 50 μm release-treated polyimide film "J0" (manufactured by Nippa Corporation) as a supporting substrate 5, and dried at 90 ° C for 2 minutes to form a conductive layer 2. The conductive layer had a line width of 1 mm, a length of 10 cm, and a thickness of 20 μm. Next, as shown in FIG. 10B, the resin varnish 1 '' of Manufacturing Example 2 was applied so that the thickness after drying was 100 μm, and dried at 80 ° C for 10 minutes and then at 110 ° C for 10 minutes. Thereafter, a release-treated PEN film "J0" (manufactured by Nippa Corporation) was laminated on the resin surface as a protective layer 6 (FIG. 10C), and the resin varnish 1 '' was cured by hot pressing at 180 ° C for 30 minutes at 4 MPa to form a resin layer 1 (FIG. 10D). Then, the protective layer 6 (PEN film) was peeled off to obtain the laminate of Example 3 (with the supporting substrate 5) (FIG. 10E).

[0093] Example 4 The manufacturing process of the laminate of Example 4 is shown in FIG. 11. First, as shown in FIG. 11A, a circuit pattern was screen-printed using copper ink "LF360" (manufactured by Copprint) on a 50 μm release-treated polyimide film "J0" (manufactured by Nippa Corporation) as a supporting substrate 5, and dried at 90° C. for 2 minutes to form a conductive layer 2. The conductive layer had a line width of 1 mm, a length of 10 cm, and a thickness of 20 μm. Next, as shown in FIG. 11B, the dry film 1' (with protective layer 6) of Manufacturing Example 2 was laminated at 80° C. and 0.3 MPa for 60 seconds using a vacuum laminator. Then, the protective layer 6 (PEN film) was peeled off from the dry film 1'. 11A to 11C, another dry film 1' from which the protective layer 6 was peeled off was prepared, and as shown in FIG. 11C, two dry films 1' with supporting substrates 5 (polyimide films) were stacked with the resin sides facing each other, and laminated for 60 seconds at 80°C and 0.3 MPa using a vacuum laminator. Then, the dry film 1' was cured by hot pressing at 180°C and 4 MPa for 30 minutes to form a resin layer 1 (FIG. 11D). Then, the supporting substrate 5 (polyimide film) was peeled off to obtain a laminate of Example 4 (FIG. 11E).

[0094] Comparative Example 1 The manufacturing process of the laminate of Comparative Example 1 is shown in Fig. 12. First, as shown in Fig. 12A, resin varnish 1'' of Production Example 2 was applied to a 50 µm release-treated polyimide film "J0" (manufactured by Nippa Corporation) as a supporting substrate 5 so that the thickness after drying would be 100 µm, and the coating was dried at 80°C for 10 minutes and then at 110°C for 10 minutes. The conductive layer had a line width of 1 mm, a length of 10 cm, and a thickness of 20 µm. Thereafter, as shown in FIG. 12B, a release-treated PEN film "SP3030" (manufactured by Toyo Cross Co., Ltd.) was laminated as a protective layer 6 on the dried resin varnish layer 1'. Then, the resin varnish layer 1' was cured by hot pressing at 180°C for 30 minutes at 4 MPa to form a resin layer 1 (FIG. 12C). Then, as shown in FIG. 12D, the protective layer 6 (PEN film) was peeled off, and a circuit pattern was screen-printed using copper ink "LF360" (manufactured by Copprint Co., Ltd.), and dried at 90°C for 2 minutes. After that, the laminate was further hot pressed at 180°C for 30 minutes at 4 MPa to form a conductive layer 2, and a laminate of Comparative Example 1 was obtained.

[0095] <Evaluation> (Bending resistance of conductive layer) A cylindrical SUS rod with a diameter of 2 mm was prepared, and in each of the laminates of the examples and the comparative examples, it was placed perpendicularly to the straight wiring with a width of 1 mm formed using each conductive layer, and bent at 90°. At this time, it was confirmed whether or not cracks occurred in the wiring. As a result, no cracks occurred in the laminates of the examples 1 to 4, whereas cracks occurred in the wiring in the laminate of the comparative example 1.

[0096] (Consideration) First, in the laminate according to the present invention, as shown in FIGS. 8 to 11 (Examples 1 to 4), it is possible to form a circuit on the back surface of the resin layer, but in Comparative Example 1, it is not possible to form a circuit on the back surface of the resin layer.

[0097] In the laminates of Examples 1 to 4, the conductive layer had bending resistance, but in the laminate of Comparative Example 1 in which the conductive layer was not embedded in the resin layer, cracks occurred in the bending test. [Explanation of symbols]

[0098] 1 Resin layer (A) 1'Resin varnish, semi-cured film, dry film 2 Conductive layer (B) 2'Second conductive layer (B') 3 Third conductive layer (B'') 4 Second resin layer (A') 5 Support substrate 6 Protective layer

Claims

1. A laminate comprising a resin layer (A) and a conductive layer (B), The resin layer (A) is elastic, A laminate, in which the conductive layer (B) is embedded in the resin layer (A) and is exposed on one of the surfaces of the resin layer (A).

2. The laminate of claim 1 , wherein the conductive layer (B) comprises silver or copper.

3. 2. The laminate of claim 1, wherein the conductive layer (B) is non-elastic.

4. 2. The laminate according to claim 1, wherein the resin layer (A) has a tensile stress at 50% elongation of 0.5 MPa or more and 100 MPa or less.

5. 2. The laminate according to claim 1, wherein the resin layer (A) has a breaking elongation of 50% or more and 700% or less.

6. The laminate according to claim 1, further comprising a second conductive layer (B') embedded in the resin layer (A) and exposed on the surface of the resin layer (A) opposite to the surface on which the conductive layer (B) is exposed.

7. The laminate of claim 6, wherein the second conductive layer (B') is non-elastic.

8. 2. The laminate according to claim 1, further comprising a second conductive layer (B') formed on the surface of the resin layer (A) opposite to the surface on which the conductive layer (B) is exposed.

9. The laminate according to claim 8, wherein the second conductive layer (B') is stretchable.

10. 9. The laminate according to claim 8, wherein at least a part of the conductive layer (B) and at least a part of the second conductive layer (B') are electrically conductive.

11. A second resin layer (A') is further provided on the resin layer (A), The second conductive layer (B') is embedded in the second resin layer (A'), The laminate according to claim 8, further comprising a third conductive layer (B'') formed on the surface of the second resin layer (A') opposite to the surface in which the conductive layer (B') is embedded.

12. The laminate according to claim 1 , further comprising a supporting substrate (C).

13. The laminate according to claim 1 , further comprising a protective layer (D).

14. An electronic device comprising the laminate according to any one of claims 1 to 13 and an electronic component.

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