Three-dimensional conductive film for transparent heaters and method for manufacturing a three-dimensional conductive film for transparent heaters

Abstract

This three-dimensional conductive film (11) for transparent heaters comprises: a substrate (12); a conductive layer (14) which is arranged on the substrate (12), while being formed of a metal mesh; and a pad (16) which is electrically connected to the conductive layer (14), and which is used for the purpose of making an electrical connection to an external circuit. With respect to this three-dimensional conductive film (11) for transparent heaters, the conductive layer (14) and the pad (16) are electrically connected to each other by the intermediary of an intermediate layer (15); the intermediate layer (15) contains a conductive material and a resin material; and the substrate (12) and the conductive layer (14) partially have a curved surface.

Description

[Technical Field]

[0001] This invention relates to a three-dimensional conductive film for transparent heaters and a method for manufacturing a three-dimensional conductive film for transparent heaters. [Background technology]

[0002] Sensors and communication devices using electromagnetic waves such as millimeter waves and microwaves have been commonly used for a long time. These devices are often mounted on vehicles, for example, and are frequently surrounded by protective covers. It is known that snow and ice accumulation on such covers, or fogging caused by water vapor, can cause false detections in sensors located inside the covers or communication problems in communication devices. To remove snow, ice, and fogging and to allow electromagnetic waves to pass through, conductive films such as the one disclosed in Patent Document 1 have been developed. The conductive film in Patent Document 1 has a wiring pattern formed by plating or etching and has a transparent heater film that is electromagnetically transparent. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-005057 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Here, when using a conductive film like the one in Patent Document 1 as a heater, it is necessary to form a pad to conduct electricity through the conductive film. However, when the conductive film in Patent Document 1 is formed three-dimensionally, stress due to the three-dimensional shape of the conductive film is applied to the joint between the wiring pattern portion that functions as a heater and the pad, as well as to the pad itself. This can lead to problems such as disconnection of the wire at the joint between the wiring pattern portion and the pad or cracking of the pad when the wiring pattern portion is heated.

[0005] This invention was made to solve these problems and aims to provide a three-dimensional conductive film for transparent heaters that suppresses failure due to heating, and a method for manufacturing a three-dimensional conductive film for transparent heaters. [Means for solving the problem]

[0006] To achieve the above objective, the three-dimensional conductive film for a transparent heater according to the present invention comprises a substrate, a conductive layer disposed on the substrate and formed of a metal mesh, and a pad electrically connected to the conductive layer and for electrically connecting to an external circuit, wherein the conductive layer and the pad are electrically connected via an intermediate layer, the intermediate layer comprises a conductive material and a resin material, and the substrate and a part of the conductive layer have a curved surface.

[0007] The resin material included in the intermediate layer preferably has a glass transition temperature of 40°C or lower. Furthermore, the middle layer is 5.0 × 10 -3 It is preferable to have a volume resistivity of Ω·cm or less.

[0008] Furthermore, the three-dimensional conductive film for the transparent heater may have an organic polymer layer positioned between the substrate and the conductive layer. The organic polymer layer preferably has a glass transition temperature of 60°C or lower.

[0009] The pad preferably has a thickness of at least twice the thickness of the conductive layer. Furthermore, it is preferable that the pad has a sheet resistance of 1 / 10 or less of the sheet resistance of the conductive layer.

[0010] The present invention relates to a method for manufacturing a three-dimensional conductive film for a transparent heater, comprising the steps of: coating a conductive layer precursor layer onto a substrate; patterning the precursor layer to include a mesh shape; simultaneously forming the substrate and the precursor layer into a three-dimensional shape; performing a plating treatment on the precursor layer to form a conductive layer; forming an intermediate layer on a part of the conductive layer; and forming a pad that is electrically connected to the conductive layer via the intermediate layer. [Effects of the Invention]

[0011] The three-dimensional conductive film for a transparent heater according to the present invention has a substrate, a conductive layer disposed on the substrate and formed of a metal mesh, and pads electrically connected to the conductive layer and for electrically connecting to an external circuit. The conductive layer and the pads are electrically connected via an intermediate layer. The intermediate layer includes a conductive material and a resin material. Since a part of the substrate and the conductive layer has a curved surface, failures due to heating of the conductive layer can be suppressed.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic perspective view of the three-dimensional conductive film for a transparent heater according to an embodiment of the present invention. [Figure 2] It is a partial cross-sectional view of the three-dimensional conductive film for a transparent heater according to an embodiment of the present invention. [Figure 3] It is a partial plan view of the conductive layer in an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, based on the preferred embodiments shown in the accompanying drawings, the energizing member of the present invention will be described in detail. Note that the drawings described below are exemplary for explaining the present invention, and the present invention is not limited to the drawings shown below. Note that "~" indicating a numerical range below includes the numerical values described on both sides. For example, when ε is a numerical value α~numerical value β, the range of ε is a range including the numerical values α and β, and in mathematical symbols, it is α≦ε≦β. Angles such as "parallel" and "orthogonal" include the error ranges generally acceptable in the relevant technical field unless otherwise specified. Also, "identical" includes the error ranges generally acceptable in the relevant technical field.

[0014] In addition, “(meth)acrylate” represents both acrylate and methacrylate, or either one of them, and “(meth)acrylic” represents both acrylic and methacrylic, or either one of them. Further, “(meth)acryloyl” represents both acryloyl and methacryloyl, or either one of them. Note that being transparent to visible light means that, unless otherwise specified, the visible light transmittance is 40% or more in the visible light wavelength range of 380 nm to 800 nm, preferably 80.0% or more, and more preferably 90.0% or more. Further, in the following description, unless otherwise specified, being transparent means being transparent to visible light. The visible light transmittance is measured using “Plastics - Methods of test for total luminous transmittance and haze” specified in JIS (Japanese Industrial Standards) K 7375:2008.

[0015] Embodiment 1 FIG. 1 shows a three - dimensional conductive film 11 for a transparent heater according to an embodiment of the present invention. The three - dimensional conductive film 11 for a transparent heater is a film - shaped member and has a three - dimensional shape (3D shape) along the curved surface of a hemisphere. Although not shown in FIG. 1, the three - dimensional conductive film 11 for a transparent heater has a conductive layer that generates heat when a voltage is applied, and pads connected to an external circuit for supplying a voltage to the conductive layer.

[0016] When a voltage is applied to the three - dimensional conductive film 11 for a transparent heater from an external circuit through the pads, the surface is heated and it functions as a so - called heater. In addition, the three - dimensional conductive film 11 for a transparent heater has a visible light transmittance of, for example, 75.0% or more. For example, an observer observing the three - dimensional conductive film 11 for a transparent heater from the outside can visually recognize the inside of the three - dimensional conductive film 11 for a transparent heater through the three - dimensional conductive film 11 for a transparent heater.

[0017] As shown in Figure 2, the three-dimensional conductive film 11 for the transparent heater comprises an insulating transparent substrate 12, an organic polymer layer 13 formed on the substrate 12, a conductive layer 14 formed on the organic polymer layer 13 and made of a metal mesh, an intermediate layer 15 formed on the edges of the organic polymer layer 13 and the conductive layer 14, and a pad 16 formed on the intermediate layer 15.

[0018] The conductive layer 14 is formed of a metal mesh M consisting of metal nanowires 17 having a line width W and a plurality of square openings 18, as shown in Figure 3, for example. Parallel and adjacent metal nanowires 17 are arranged with a pitch P defined as the distance between the centerlines CL of the metal nanowires 17. Thus, the conductive layer 14 is formed of a metal mesh M and has, for example, a visible light transmittance of 75.0% or more.

[0019] The wire width W of the metal wire 17 is not particularly limited, but the upper limit is preferably 1000.00 μm or less, more preferably 500.00 μm or less, and even more preferably 300.00 μm or less. The lower limit of the wire width W is preferably 2.00 μm or more, and more preferably 5.00 μm or more. If the wire width W is within the above range, the metal mesh M can have high conductivity. Also, from the viewpoint of conductivity, the thickness of the metal wire 17 can be set to 0.01 μm or more and 200.00 μm or less, but the upper limit is preferably 30.00 μm or less, more preferably 20.00 μm or less, even more preferably 9.00 μm or less, and particularly preferably 3.00 μm or less. The lower limit of the thickness of the metal wire 17 is preferably 0.01 μm or more, and more preferably 0.05 μm or more.

[0020] The sheet resistance of the conductive layer 14 is preferably 0.10 Ω / □ or more and 10.00 Ω / □ or less. Thus, because the conductive layer 14 has a sufficiently low sheet resistance, it has high reflectivity to so-called radio waves. Furthermore, because the conductive layer 14 has a resistance value of 0.10 Ω / □ or more, it generates heat when current is passed through it, exhibiting a so-called heater function.

[0021] Furthermore, in order to ensure that the presence of the metal mesh M is not noticeable when a user attempts to visually inspect the three-dimensional conductive film 11 for the transparent heater, and that the three-dimensional conductive film 11 for the transparent heater has sufficient transparency, the upper limit of the pitch P is preferably 800.00 μm or less, more preferably 600.00 μm or less, and even more preferably 400.00 μm or less. The lower limit of the pitch P is preferably 5.00 μm or more, more preferably 30.00 μm or more, and even more preferably 80.00 μm or more.

[0022] Furthermore, since the three-dimensional conductive film 11 for the transparent heater has a visible light transmittance of 75.0% or more, the aperture ratio of the metal mesh M is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more. Here, the aperture ratio of the metal mesh M refers to the proportion of the transparent portion of the area occupied by the metal mesh M excluding the metal wires 17, that is, it corresponds to the ratio of the total area occupied by the multiple openings 18 to the total area of ​​the metal mesh M.

[0023] Furthermore, the shape of the multiple openings 18 in the metal mesh M is not limited to squares, but can be, for example, triangles such as equilateral triangles, isosceles triangles, and right triangles; quadrilaterals such as squares, rectangles, parallelograms, and trapezoids; regular polygons such as regular hexagons and regular octagons; circles; ellipses or stars; or geometric figures that combine these shapes.

[0024] Here, if a portion of the substrate 12 and the conductive layer 14 has a curved surface, it is thought that stress is applied between the substrate 12 and the conductive layer 14 due to the strain that occurs in the substrate 12 when it is three-dimensionally molded, and also between the conductive layer 14 and the pad 16. Furthermore, when the conductive layer 14 is heated, in addition to the stress caused by the strain of the three-dimensional substrate 12, it is thought that stress caused by the expansion or contraction of the conductive layer 14 is applied between the substrate 12 and the conductive layer 14, and between the conductive layer 14 and the pad 16. It is also possible that when the conductive layer 14 is heated, the heat conducted from the conductive layer 14 to the pad 16 causes the pad 16 to expand or contract, creating stress between the conductive layer 14 and the pad 16.

[0025] The stress generated between the substrate 12 and the conductive layer 14, and between the conductive layer 14 and the pad 16, due to the heating of the conductive layer 14, can cause failures of the three-dimensional conductive film 11 for the transparent heater, such as disconnection of the joint between the conductive layer 14 and the pad 16, and cracking of the pad 16 itself.

[0026] The intermediate layer 15 comprises a conductive material and a resin material, and is a layer that electrically connects the conductive layer 14 and the pad 16. The intermediate layer 15 is formed, for example, by dispersing fine particles made of a conductive material such as metal in the resin material.

[0027] Furthermore, the resin material softens when the conductive layer 14 is heated. This allows the stress on the conductive layer 14 and the pad 16 to be relieved even if the conductive layer 14 expands or contracts due to heating, and the pad 16 expands or contracts due to the heat of the conductive layer 14. This suppresses, for example, disconnection of the joint between the conductive layer 14 and the pad 16, and also suppresses cracking of the pad 16 itself, even when the conductive layer 14 is heated. The resin material of the intermediate layer 15 preferably has a glass transition temperature of 40°C or less, and in particular preferably has a glass transition temperature of 0°C or less, in order to sufficiently relieve the stress on the conductive layer 14 and the pad 16 when the conductive layer 14 is heated. The lower limit of the glass transition temperature of the resin material of the intermediate layer 15 is not particularly limited, but it is preferably -100°C or higher.

[0028] Furthermore, the intermediate layer 15 is 5.0 × 10 in order to ensure sufficient electrical connection between the conductive layer 14 and the pad 16, and to ensure that the heat from the heated conductive layer 14 is sufficiently conducted to the intermediate layer 15 so that the intermediate layer 15 softens easily. -3 Preferably, it has a volume resistivity of Ω·cm or less, and in particular, 3.5 × 10⁻⁶. -3 It is preferable that the volume resistivity be Ω·cm or less. The lower limit of the volume resistivity of the intermediate layer 15 is not particularly limited, but is 1.5 × 10⁻⁶. -3 It is preferable that the density is Ω·cm or greater.

[0029] The organic polymer layer 13 is a layer composed of a resin made of organic compounds that softens upon heating.

[0030] Even if the conductive layer 14 expands or contracts due to heating, the organic polymer layer 13 softens due to the heat of the conductive layer 14, thereby relieving the stress on the substrate 12 and the conductive layer 14. This suppresses, for example, disconnection of the conductive layer 14 even when the conductive layer 14 is heated. The organic polymer layer 13 preferably has a glass transition temperature of 60°C or lower, and more preferably 55°C or lower, in order to sufficiently relieve the stress on the substrate 12 and the conductive layer 14 when the conductive layer 14 is heated. The lower limit of the glass transition temperature of the organic polymer layer 13 is not particularly limited, but it is preferably -70°C or higher.

[0031] The pad 16 is made of a conductive material such as metal and is used to transmit a voltage applied from an external circuit (not shown) to the conductive layer 14. For example, one end is electrically connected to an external circuit (not shown), and the other end is electrically connected to the conductive layer 14 via the intermediate layer 15.

[0032] Furthermore, to prevent cracking even if the conductive layer 14 expands or contracts due to heat when the conductive layer 14 is heated, the pad 16 preferably has a thickness ratio of 2 or more to the thickness of the conductive layer 14, more preferably 4 or more, and particularly preferably 5 or more. There is no particular upper limit to the thickness ratio of the pad 16 to the thickness of the conductive layer 14, but it is preferably 100 or less, and even more preferably 60 or less.

[0033] Furthermore, the lower the sheet resistance of the pad 16 is compared to the sheet resistance of the conductive layer 14, the easier it is for heat generated in the conductive layer 14 to be conducted to the pad 16. Since the pad 16 is electrically connected to an external circuit (not shown), the heat conducted from the conductive layer 14 to the pad 16 is further conducted to the external circuit. In this way, the lower the sheet resistance of the pad 16 is compared to the sheet resistance of the conductive layer 14, the more heat generated in the conductive layer 14 is conducted to the outside, and excessive heating of the junction between the conductive layer 14 and the pad 16 is suppressed. From this viewpoint, the sheet resistance ratio of the pad 16 to the sheet resistance of the conductive layer 14 is preferably 0.1 or less, and particularly preferably 0.05 or less. There is no particular upper limit to the sheet resistance ratio of the pad 16 to the sheet resistance of the conductive layer 14, but it is preferably 0.001 or more.

[0034] As described above, according to the three-dimensional conductive film 11 for transparent heaters according to the embodiment of the present invention, even if the conductive layer 14 is heated and the conductive layer 14 and pad 16 expand or contract, causing stress on the conductive layer 14 and pad 16, the intermediate layer 15 relieves the stress on the conductive layer 14 and pad 16. Therefore, failures of the three-dimensional conductive film 11 for transparent heaters due to heating of the conductive layer 14, such as disconnection of the joint between the conductive layer 14 and pad 16 and cracking of the pad 16 itself, are suppressed.

[0035] Furthermore, the organic polymer layer 13 relieves the stress on the substrate 12 and the conductive layer 14, thereby suppressing failure of the three-dimensional conductive film 11 for the transparent heater due to heating of the conductive layer 14.

[0036] Although the transparent heater's three-dimensional conductive film 11 is described as having a three-dimensional shape that follows the curved surface of a hemisphere, the three-dimensional shape of the transparent heater's three-dimensional conductive film 11 is not limited to a shape that follows a hemisphere. The three-dimensional shape of the transparent heater's three-dimensional conductive film 11 can have complex three-dimensional shapes that follow, for example, an automobile emblem, a radar radome, a radar front cover, an automobile headlamp cover, an antenna, or a reflector.

[0037] The following describes in detail each component of the three-dimensional conductive film 11 for the transparent heater. <Circuit board> The substrate 12 is not particularly limited as long as it is insulating and can support the organic polymer layer 13, conductive layer 14, intermediate layer 15 and pad 16, but it is preferably transparent and preferably made of a resin material.

[0038] Specific examples of resin materials constituting the substrate 12 include polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polycarbonate (PC), polycycloolefin, (meth)acrylic, polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinylidene difluoride (PVDF), polyarylate (PAR), polyethersulfone (PES), polymeric acrylic, fluorene derivatives, and crystalline cycloolefin polymers (CycloOlefin Examples include polymers (COP) and triacetylcellulose (TAC).

[0039] Here, from the viewpoint of transparency and durability of the substrate 12, it is preferable that the substrate 12 is mainly composed of one of the following: polymethyl methacrylate resin, polycarbonate resin, acrylonitrile butadiene styrene resin, or polyethylene terephthalate resin. Here, the main component of the substrate 12 means that it accounts for 80% or more of the constituent components of the substrate 12.

[0040] The visible light transmittance of the substrate 12 is preferably 85.0% to 100.0%. Furthermore, while there are no particular restrictions on the thickness of the substrate 12, it is preferable that it be 0.05 mm or more and 2.00 mm or less, and more preferably 0.10 mm or more and 1.00 mm or less, from the standpoint of ease of handling.

[0041] <Thin metal wire> The type of conductive material constituting the metal fine wires 17 of the conductive layer 14 is not particularly limited, and examples include copper, silver, aluminum, chromium, lead, nickel, gold, tin, and zinc, but copper, silver, aluminum, or gold are more preferred from the viewpoint of conductivity.

[0042] <pad> The type of conductive material constituting the pad 16 is not particularly limited, and like the material of the metal wire 17, examples include copper, silver, aluminum, chromium, lead, nickel, gold, tin, and zinc, but from the viewpoint of conductivity, copper, silver, aluminum, or gold are more preferred.

[0043] <Organic polymer layer> The organic polymer layer 13 contains a polymer having interacting groups that interact with the plating catalyst or its precursor. In particular, it is preferable that the organic polymer layer 13 is formed by curing an organic polymer layer precursor layer containing a radical polymerizable monomer that hardens in response to UV light by irradiation with UV light.

[0044] <Middle class> The intermediate layer 15 contains a conductive material and a resin material, and is composed of fine particles made of a conductive material such as metal dispersed in the resin material. Examples of the conductive material included in the intermediate layer 15 include flake-shaped or spherical gold powder, silver powder, copper powder, nickel powder, aluminum powder, plating powder, carbon powder, or graphite powder. Examples of the resin material included in the intermediate layer 15 include epoxy resin, urethane resin, silicone resin, acrylic resin, polyimide resin, or other thermosetting resins or thermoplastic resins.

[0045] <Preferred embodiment of a method for manufacturing a three-dimensional conductive film for a transparent heater> The following is a preferred embodiment of the method for manufacturing the three-dimensional conductive film 11 for transparent heaters, which includes the following steps 1 to 6. Step 1: Process of coating the substrate with a conductive layer precursor layer. Step 2: A process of patterning the conductive layer precursor layer to include a mesh shape. Step 3: A process for simultaneously forming the substrate and the conductive layer precursor into a three-dimensional shape. Step 4: Plating treatment is performed on the precursor layer to form a conductive layer. Step 5: Step of forming an intermediate layer on a portion of the conductive layer. Step 6: A step to form a pad that is electrically connected to the conductive layer via an intermediate layer. The following details each step.

[0046] <Process 1> Step 1 is the process of coating the substrate with a conductive layer precursor layer. The components and materials used in this process are described in detail below.

[0047] In step 1, the aforementioned substrate may be used as the substrate.

[0048] (Conductive layer precursor layer) The conductive layer precursor layer is a layer placed on one surface of the substrate and is a layer for forming a patterned conductive layer. The conductive layer precursor layer may be placed on the substrate so as to be in direct contact with the substrate, or it may be placed on the substrate via the organic polymer layer described above.

[0049] The conductive layer precursor layer has functional groups (hereinafter also referred to as "interacting groups") that can interact with the plating catalyst or its precursor, and polymerizable groups. Details of the interacting groups and polymerizable groups will be described later.

[0050] The thickness of the conductive layer precursor is not particularly limited, but is preferably 0.05 μm to 2.00 μm, and more preferably 0.10 μm to 1.00 μm, in that it can adequately support the plating catalyst or its precursor.

[0051] The conductive layer precursor preferably contains the following compound X or composition Y. Compound X: A compound having an interacting group and a polymerizable group. Composition Y: A composition comprising a compound having an interacting group and a compound having a polymerizable group.

[0052] Compound X is a compound that has both an interacting group and a polymerizable group. Interacting groups are defined as functional groups that can interact with the plating catalyst or its precursor applied to the conductive layer precursor. Examples include functional groups capable of forming electrostatic interactions with the plating catalyst or its precursor, as well as nitrogen-containing functional groups, sulfur-containing functional groups, and oxygen-containing functional groups capable of coordinating with the plating catalyst or its precursor.

[0053] Interacting groups include, for example, amino groups, amide groups, imide groups, urea groups, tertiary amino groups, ammonium groups, amidino groups, triazine groups, triazole groups, benzotriazole groups, imidazole groups, benzimidazole groups, quinoline groups, pyridine groups, pyrimidine groups, pyrazine groups, quinazoline groups, quinoxaline groups, purine groups, triazine groups, piperidine groups, piperazine groups, pyrrolidine groups, pyrazole groups, aniline groups, groups containing alkylamine structures, groups containing isocyanuric structures, nitro groups, nitroso groups, azo groups, diazo groups, azide groups, cyano groups, and nitrogen-containing functional groups such as cyanate groups; ether groups, hydroxyl groups, phenolic hydroxyl groups, carboxylic acid groups, carbonate groups, carbonyl groups, ester groups, N- Examples include oxygen-containing functional groups such as groups containing an oxide structure, groups containing an S-oxide structure, and groups containing an N-hydroxyl structure; sulfur-containing functional groups such as thiophene groups, thiol groups, thiourea groups, thiocyanuric acid groups, benzthiazole groups, mercaptotriazine groups, thioether groups, thioxy groups, sulfoxide groups, sulfone groups, sulfite groups, groups containing a sulfoximine structure, groups containing a sulfoxynium salt structure, sulfonic acid groups, and groups containing a sulfonic acid ester structure; phosphorus-containing functional groups such as phosphate groups, phosphoroamide groups, phosphine groups, and groups containing a phosphate ester structure; and groups containing halogen atoms such as chlorine atoms and bromine atoms. In the case of functional groups that can take a salt structure, salts thereof can also be used. In particular, ionic polar groups such as carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, and boronic acid groups, or cyano groups are preferred due to their high polarity and high adsorption capacity to plating catalysts or their precursors, with carboxylic acid groups or cyano groups being more preferred. Compound X may have two or more interacting groups.

[0054] Polymerizable groups are functional groups that can form chemical bonds through energy transfer, and examples include radical polymerizable groups and cationic polymerizable groups. Among these, radical polymerizable groups are preferred due to their superior reactivity. Examples of radical polymerizable groups include alkenyl groups (e.g., -C=C-), acrylic acid ester groups (acryloyloxy groups), methacrylic acid ester groups (methacryloyloxy groups), itaconic acid ester groups, crotonic acid ester groups, isocrotonic acid ester groups, maleic acid ester groups, styryl groups, vinyl groups, acrylamide groups, and methacrylamide groups. Among these, alkenyl groups, methacryloyloxy groups, acryloyloxy groups, vinyl groups, styryl groups, acrylamide groups, or methacrylamide groups are preferred, and methacryloyloxy groups, acryloyloxy groups, or styryl groups are more preferred. Compound X may have two or more polymerizable groups. Furthermore, there is no particular limit to the number of polymerizable groups in compound X; it may be one or two or more.

[0055] The compound X described above may be either a low-molecular-weight compound or a high-molecular-weight compound. A low-molecular-weight compound is defined as a compound with a molecular weight of less than 1000, while a high-molecular-weight compound is defined as a compound with a molecular weight of 1000 or more.

[0056] If the above compound X is a polymer, the weight-average molecular weight of the polymer is not particularly limited, but is preferably 1,000 to 700,000, and more preferably 2,000 to 200,000, in terms of superior handling properties such as solubility. The method for synthesizing polymers having such polymerizable and interacting groups is not particularly limited, and known synthesis methods can be used (see paragraphs

[0097] to

[0125] of Japanese Patent Application Publication No. 2009-280905).

[0057] Composition Y is a composition containing a compound having an interacting group and a compound having a polymerizable group. In other words, composition Y contains two types of compounds: a compound having an interacting group and a compound having a polymerizable group. The definitions of interacting groups and polymerizable groups are as described above. Compounds containing interacting groups may be low-molecular-weight compounds or high-molecular-weight compounds. Furthermore, compounds containing interacting groups may also contain polymerizable groups. Preferred forms of compounds having interacting groups include polymers containing repeating units having interacting groups (e.g., polyacrylic acid). One preferred form of a repeating unit having an interacting group is the repeating unit represented by formula (A).

[0058] [ka]

[0059] In formula (A), R 1 This represents a hydrogen atom or an alkyl group (e.g., a methyl group, an ethyl group, etc.). L 1 -R represents a single bond or a divalent linking group. The type of divalent linking group is not particularly limited and includes, for example, divalent hydrocarbon groups (which may be divalent saturated hydrocarbon groups or divalent aromatic hydrocarbon groups. Divalent saturated hydrocarbon groups may be linear, branched, or cyclic, and preferably have 1 to 20 carbon atoms, for example, alkylene groups. Divalent aromatic hydrocarbon groups preferably have 5 to 20 carbon atoms, for example, phenylene groups. Other examples include alkenylene groups and alkylylene groups.), divalent heterocyclic groups, -O-, -S-, -SO2-, -NR-, -CO-(-C(=O)-), -COO-(-C(=O)O-), -NR-CO-, -CO-NR-, -SO3-, -SO2NR-, and groups formed by combining two or more of these. Here, R represents a hydrogen atom or an alkyl group (preferably having 1 to 10 carbon atoms). Z represents an interacting group. The definition of an interacting group is as described above.

[0060] Other preferred forms of repeating units having interacting groups include repeating units derived from unsaturated carboxylic acids or their derivatives. Unsaturated carboxylic acids are unsaturated compounds that have a carboxylic acid group (-COOH group). Examples of derivatives of unsaturated carboxylic acids include anhydrides of unsaturated carboxylic acids, salts of unsaturated carboxylic acids, and monoesters of unsaturated carboxylic acids. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0061] The content of repeating units having interacting groups in a polymer containing such repeating units is not particularly limited, but in terms of balancing plating deposition properties, 1 to 100 mol% is preferred and 10 to 100 mol% is more preferred relative to the total number of repeating units.

[0062] Preferred forms of polymers containing repeating units with interacting groups include polymer Z having repeating units derived from conjugated diene compounds and repeating units derived from unsaturated carboxylic acids or their derivatives, as these allow for the formation of an insulating layer with a small amount of energy input (e.g., exposure). The explanation of the repeating units derived from unsaturated carboxylic acids or their derivatives is as described above.

[0063] The conjugated diene compound is not particularly limited as long as it has a molecular structure having two carbon-carbon double bonds separated by a single bond. Examples of conjugated diene compounds include isoprene, 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadien, 2,4-nonadien, 3,5-nonadien, 1,3-decadien, 2,4-decadien, 3,5-decadien, 2,3-dimethylbutadiene, and 2-methyl-1,3-pentadiene. Examples include tadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2-hexyl-1,3-butadiene, 3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, and 2-p-tolyl-1,3-butadiene.

[0064] In particular, the repeating units derived from the conjugated diene compound are preferably those derived from a compound having a butadiene skeleton represented by formula (2), because polymer Z is easy to synthesize and the properties of the patterned insulating layer are superior.

[0065] [ka]

[0066] In formula (2), R 2 Each of these independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group. Examples of hydrocarbon groups include aliphatic hydrocarbon groups (e.g., alkyl groups, alkenyl groups, etc., preferably with 1 to 12 carbon atoms) and aromatic hydrocarbon groups (e.g., phenyl groups, naphthyl groups, etc.). 2 They may be the same or different.

[0067] Examples of compounds having a butadiene skeleton (monomers having a butadiene structure) include 1,3-butadiene, isoprene, 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl-1,3-butadiene, 2-chlor-1,3-butadiene, 1-brom-1,3-butadiene, 1-chlorbutadiene, 2-fluoro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 1,1,2-trichlor-1,3-butadiene, and 2-cyano-1,3-butadiene.

[0068] The content of repeating units derived from conjugated diene compounds in polymer Z is preferably 25 to 75 mol% relative to the total number of repeating units. The content of repeating units derived from unsaturated carboxylic acids or their derivatives in polymer Z is preferably 25 to 75 mol% relative to the total number of repeating units.

[0069] A compound having polymerizable groups is a so-called monomer, and a polyfunctional monomer having two or more polymerizable groups is preferred in that it provides superior hardness to the formed patterned insulating layer. Specifically, a polyfunctional monomer having 2 to 6 polymerizable groups is preferred. In terms of molecular mobility during the crosslinking reaction, which affects reactivity, the molecular weight of the polyfunctional monomer used is preferably 150 to 1000, and more preferably 200 to 800.

[0070] As the polyfunctional monomer, amide compounds selected from the group consisting of polyfunctional acrylamide and polyfunctional methacrylamide are preferred. A polyfunctional acrylamide contains two or more acrylamide groups. The number of acrylamide groups in a polyfunctional acrylamide is not particularly limited, but is preferably 2 to 10, more preferably 2 to 5, and even more preferably 2. The polyfunctional methacrylamide contains two or more methacrylamide groups. The number of methacrylamide groups in the polyfunctional methacrylamide is not particularly limited, preferably 2 to 10, more preferably 2 to 5. The acrylamide group and the methacrylamide group are groups represented by the following formulas (B) and (C), respectively. * represents the bonding position.

[0071]

Chemical formula

[0072] R 3 represents a hydrogen atom or a substituent. The type of the substituent is not particularly limited, and examples thereof include known substituents (for example, an aliphatic hydrocarbon group which may contain a hetero atom, an aromatic hydrocarbon group, etc. More specifically, an alkyl group, an aryl group, etc.).

[0073] As a preferred embodiment of the compound having a polymerizable group, a compound represented by the formula (1) can be mentioned.

[0074]

Chemical formula

[0075] In the formula (1), Q represents an n-valent linking group, and R a represents a hydrogen atom or a methyl group. n represents an integer of 2 or more.

[0076] R a represents a hydrogen atom or a methyl group, preferably a hydrogen atom. The valence number n of Q is 2 or more, and from the viewpoint of further improving the adhesion between the insulating layer and the metal layer, 2 to 6 is preferable, 2 to 5 is more preferable, and 2 to 4 is even more preferable. Examples of n-valent linking groups represented by Q include the group represented by formula (1A), the group represented by formula (1B), -NH-, -NR (R: representing an alkyl group)-, -O-, -S-, carbonyl group, alkylene group, alkenylene group, alkynylene group, cycloalkylene group, aromatic group, heterocyclic group, and groups formed by combining two or more of these.

[0077] [ka]

[0078] The content of compound X (or composition Y) in the conductive layer precursor is not particularly limited, but is preferably 50% by mass or more, and more preferably 80% by mass or more, relative to the total mass of the conductive layer precursor. The upper limit is 100% by mass. When the conductive layer precursor layer contains composition Y, the content of the compound having interacting groups in the conductive layer precursor layer is not particularly limited, but is preferably 10 to 90% by mass, more preferably 25 to 75% by mass, and even more preferably 35 to 65% by mass, relative to the total mass of the conductive layer precursor layer. The mass ratio of the compound having an interacting group to the compound having a polymerizable group (mass of the compound having an interacting group / mass of the compound having a polymerizable group) is not particularly limited, but is preferably 0.1 to 10.0 and more preferably 0.5 to 2.0 in terms of balancing the strength and plating suitability of the formed patterned insulating layer.

[0079] The conductive layer precursor layer may optionally contain other components (e.g., polymerization initiators, sensitizers, curing agents, polymerization inhibitors, antioxidants, antistatic agents, fillers, flame retardants, lubricants, plasticizers, or plating catalysts or their precursors).

[0080] The method for forming the conductive layer precursor is not particularly limited. For example, one method involves bringing a substrate into contact with a composition containing compound X or composition Y to form the conductive layer precursor on the substrate. The method for bringing the above composition into contact with the substrate is not particularly limited, and examples include coating the composition onto the substrate or immersing the substrate in the composition. Furthermore, if necessary, after bringing the above composition into contact with the substrate, a drying treatment may be performed to remove the solvent from the insulating layer precursor layer.

[0081] The above composition may contain a solvent. The type of solvent is not particularly limited and includes water and organic solvents.

[0082] (Step 1 procedure) In step 1, the conductive layer precursor layer prepared as described above is applied to one surface of the substrate.

[0083] <Process 2> Step 2 is a process of patterning the conductive layer precursor layer to include a mesh shape. In Step 2, the conductive layer precursor layer is subjected to exposure and development processes to form a patterned precursor layer.

[0084] In the exposure process, the conductive layer precursor is irradiated with light in a patterned manner to obtain the desired patterned precursor layer. The type of light used is not particularly limited, and examples include ultraviolet light and visible light. When irradiating with light in a patterned manner, it is preferable to use a mask having an opening of a predetermined shape.

[0085] In the exposed areas of the conductive layer precursor, polymerizable groups contained in the conductive layer precursor are activated, crosslinking occurs between compounds, and the layer hardens. While there are no particular restrictions on the irradiation energy during the exposure process, 300 mJ / cm² is recommended for easier formation of the insulating layer with the shape described above. 2 The above is preferable, with a concentration of 400 mJ / cm². 2 The above is preferable. There is no particular upper limit, but 2000 mJ / cm² is preferable. 2 The following are common cases. Furthermore, when exposure treatment is performed using the polymer Z described above at the above irradiation energy, a precursor layer with the above-described shape is easily formed.

[0086] Next, the conductive precursor layer, which has been cured in a patterned manner, is subjected to a developing process, which removes the unexposed areas and forms a patterned precursor layer. The developing process is not particularly limited, and the optimal developing process is carried out according to the type of material used. Examples of developing solutions include organic solvents, pure water, and alkaline aqueous solutions.

[0087] The patterned precursor layer formed by the above procedure is a layer having functional groups that interact with the plating catalyst or its precursor, and is arranged in a predetermined pattern. The patterned precursor layer typically contains a compound having the interacting groups described above. Polymers are preferred as the compound. In other words, the patterned precursor layer preferably contains a polymer with repeating units having interacting groups.

[0088] The thickness of the patterned precursor layer is not particularly limited, but is preferably 0.05 μm to 2.00 μm, and more preferably 0.10 μm to 1.00 μm, in terms of being able to adequately support the plating catalyst or its precursor and preventing plating abnormalities.

[0089] <Process 3> Step 3 is a process in which the substrate and the patterned precursor layer are simultaneously molded into a three-dimensional shape. The method of three-dimensional molding is not particularly limited and known methods can be used. Examples of known methods for three-dimensional molding include vacuum forming, blow forming, free blow forming, pressure forming, vacuum-pressure forming, and hot press forming.

[0090] <Step 4> Step 4 is a process of plating the precursor layer to form a conductive layer. The plating method is not particularly limited and examples include electroless plating or electrolytic plating. In this process, electroless plating may be performed alone, or electrolytic plating may be performed after electroless plating. The type of plating treatment is not particularly limited; for example, copper plating and silver plating can be used.

[0091] <Process 5> Step 5 is the process of forming an intermediate layer on a portion of the conductive layer. The intermediate layer comprises a conductive material and a resin material, and for example, conductive fine particles, such as those found in a conductive adhesive, are dispersed in the resin material. For example, an intermediate layer is formed by applying a conductive adhesive from one end of the conductive layer onto the substrate, and then applying the conductive adhesive from the other end of the conductive layer onto the substrate, and then drying the applied conductive adhesive.

[0092] <Process 6> Step 6 is the process of forming a pad that is electrically connected to the conductive layer via an intermediate layer. For example, metal foil can be used as the pad. The pad is formed by placing a metal foil on top of the conductive adhesive, etc., which has been applied to the substrate and a portion of the conductive layer in step 5 before it dries, and then drying the conductive adhesive, etc.

[0093] Before step 1 is performed, a step of coating the substrate with an organic polymer layer may be carried out. [Examples]

[0094] The present invention will be described in more detail below based on the following examples. The materials, amounts used, proportions, processing content, processing procedures, etc., shown in the following examples can be modified as appropriate without departing from the spirit of the present invention, and the scope of the present invention should not be interpreted as being limited by the following examples.

[0095] <Example 1> (Preparation of the circuit board) A polycarbonate resin film with a thickness of 250.00 μm (UV244 manufactured by Covestro Japan Co., Ltd.) was prepared as the substrate.

[0096] (Preparation of compositions for forming organic polymer layers) The following components were mixed to obtain a composition for forming an organic polymer layer. Light Ester IB (Kyoeisha Chemical Co., Ltd.) 31 parts by mass FOM03006 (Fujifilm Wako Pure Chemical Industries) 2 parts by mass OXE-02 (BASF) 1 part by mass Methyl ethyl ketone 30 parts by mass Isopropanol 36 parts by mass

[0097] (Fabrication of substrates with organic polymer layers) The obtained organic polymer layer-forming composition was bar-coated onto a substrate to an average dry film thickness of 1.0 μm and dried at 80°C for 3 minutes. Subsequently, the formed organic polymer layer-forming composition was irradiated with ultraviolet (UV) light at an irradiation dose of 100 mJ to form an organic polymer layer with a thickness of 0.8 μm. The glass transition temperature of this organic polymer layer was 55°C.

[0098] (Preparation of composition for forming conductive layer precursor layer) The following components were mixed to obtain a composition for forming a conductive layer precursor. Isopropanol 38 parts by mass Polybutadiene maleic acid 4 parts by mass FAM-401 (Fujifilm Wako Pure Chemical Industries) 1 part by mass OXE-02 (BASF) 0.05 part by mass (ClogP=6.55)

[0099] (Application of composition for forming conductive layer precursor layer) The conductive layer precursor composition was coated onto an organic polymer layer in a bar to achieve an average dry film thickness of 0.2 μm, dried at 120°C for 1 minute, and immediately laminated onto the coated conductive layer precursor composition.

[0100] (Patterning of the conductive layer precursor layer) A film mask with a mesh-like pattern as shown in Figure 3 was placed over a substrate with a conductive layer precursor, and UV irradiation (energy: 100 mJ / cm2, wavelength: 365 nm) was performed through the film mask. Next, the substrate with the conductive layer precursor was developed with a pure water shower for 5 minutes to produce a 10 cm × 10 cm substrate with a mesh-like conductive layer precursor. The aperture ratio of the mesh-like pattern on the film mask was 95%.

[0101] (3D molding) A substrate with a mesh-patterned conductive layer precursor was placed on a jig with multiple through-holes that conformed to the curved surface of a hemisphere. The substrate with the conductive layer precursor was heated, and when the temperature of the substrate with the conductive layer precursor reached approximately 160°C, a vacuum was applied to bring the substrate with the conductive layer precursor into close contact with the jig. This process resulted in the substrate with the conductive layer precursor being three-dimensionally molded into a shape that conformed to the curved surface of a hemisphere, as shown in Figure 1.

[0102] (Formation of conductive layer) A substrate with a three-dimensionally molded mesh pattern conductive layer precursor was immersed in a 1% by mass sodium bicarbonate aqueous solution at 35°C for 5 minutes. Next, the substrate with the conductive layer precursor was immersed in a Pd catalyst-granting solution RONAMERSE SMT (ROHM & Haas Electronic Materials Co., Ltd.) at 55°C for 5 minutes. After rinsing the substrate with the conductive layer precursor with water, it was then immersed in CIRCUPOSIT 6540 (ROHM & Haas Electronic Materials Co., Ltd.) at 35°C for 5 minutes and rinsed again with water. Subsequently, the substrate with the conductive layer precursor was immersed in CIRCUPOSIT 4500 (ROHM & Haas Electronic Materials Co., Ltd.) at 45°C for 20 minutes to form a copper mesh pattern conductive layer. At this time, the thickness of the copper mesh pattern conductive layer was 3 μm.

[0103] (Blackening treatment) The conductive layer of the obtained copper mesh pattern was immersed in OPC Black Copper (Okuno Pharmaceutical Co., Ltd.) at 30°C for 3 minutes, washed with water, and a blackened conductive layer of the copper mesh pattern was obtained.

[0104] (Pad formation) An intermediate layer was formed by applying SX-ECA48 (manufactured by Cemedyne Co., Ltd.) to the conductive layer and organic polymer layer, overlapping one end of the obtained conductive layer by 1 mm. Similarly, an intermediate layer was formed on the other end of the conductive layer by applying conductive SX-ECA48 to the conductive layer and organic polymer layer, overlapping by 1 mm. Subsequently, electrolytic copper foil CF-T49A-SV-18 (18 μm thick) was attached to the intermediate layer formed at one end of the conductive layer and the intermediate layer formed at the other end of the conductive layer, and cured at 40°C for 1 hour to form a conductive layer with pads. At this time, the sheet resistance of the pad was 0.02 Ω / □. The volume resistivity of the SX-ECA48 used here was 3.0 × 10⁻⁶ under the above conditions. -3 The coefficient of gravity was Ω·cm, and the glass transition temperature was -60°C. Furthermore, the sheet resistance of the conductive layer was 1.00Ω / □. In this way, the three-dimensional conductive film for the transparent heater of Example 1 was manufactured.

[0105] Here, the thickness ratio of the pad to the thickness of the conductive layer was calculated to be 18 (μm) / 3 (μm) = 6. Furthermore, the sheet resistance ratio of the pad to the sheet resistance of the conductive layer was calculated to be 0.02 (Ω / □) / 1.00 (Ω / □) = 0.02.

[0106] (Example 2) The three-dimensional conductive film for the transparent heater in Example 2 was manufactured in the same manner as in Example 1, except that a conductive adhesive described in Example 1 of International Publication No. 17 / 195400 was prepared and used instead of SX-ECA48, and electrolytic copper foil CF-T49A-SV-18 (18 μm thick) was attached to it and dried for one day to form an intermediate layer and pad. The sheet resistance of the pad in Example 2 was 0.02 Ω / □. The volume resistivity of the intermediate layer was 5.0 × 10⁻⁶. -3 The coefficient of glass was Ω·cm, and the glass transition temperature was 45°C. Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.02, as in Example 1.

[0107] (Example 3) A three-dimensional conductive film for a transparent heater was manufactured in the same manner as in Example 1, except that the composition for forming the organic polymer layer was obtained by mixing the following components. The glass transition temperature of the organic polymer layer in Example 3 was 79°C. Light ester IB 25 parts by mass FOM03006 8 parts by mass Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.02, as in Example 1.

[0108] (Example 4) A three-dimensional conductive film for a transparent heater according to Example 4 was manufactured in the same manner as in Example 1, except that an organic polymer layer was not formed. Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.02, as in Example 1.

[0109] (Example 5) The transparent heater three-dimensional conductive film of Example 5 was manufactured in the same manner as in Example 1, except that the SX-ECA48 was cured at 20°C for 1 hour instead of 40°C for 1 hour during the pad formation process. The volume resistivity of the intermediate layer in Example 5 was 9.0 × 10⁻⁶. -3 It was Ω·cm. Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.02, as in Example 1.

[0110] (Example 6) Except for using a photomask with a mesh-like pattern and a pattern corresponding to a 10cm x 1cm pad, the process for forming the conductive layer was carried out in the same manner as in Example 1. After that, without performing a blackening treatment, the pad portion of the same layer as the conductive layer formed on the organic polymer layer was cut out, SX-ECA48 was applied to one end and the other end of the conductive layer, and the cut-out pad portion was placed on the SX-ECA48 in place of the electrolytic copper foil CF-T49A-SV-18 (18μm thick) to form a pad, thereby manufacturing the three-dimensional conductive film for a transparent heater of Example 6. The sheet resistance of the pad in Example 6 was 0.1Ω / □, and the thickness of the pad was 4μm. Furthermore, the ratio of the pad thickness to the conductive layer thickness was 1, since the pad thickness and the conductive layer thickness were the same, and the ratio of the pad's sheet resistance to the conductive layer's sheet resistance was 0.1(Ω / □) / 1.00(Ω / □)=0.1.

[0111] (Example 7) A three-dimensional conductive film for a transparent heater was manufactured in the same manner as in Example 1, except that the electrolytic copper foil CF-T49A-SV-18 (18 μm thick) was subjected to a blackening treatment. The sheet resistance of the pad in Example 7 was 0.2 Ω / □. Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.2(Ω / □) / 1.00(Ω / □)=0.2.

[0112] The three-dimensional conductive film for the transparent heater of Example 8 was manufactured in the same manner as in Example 1, except that a conductive adhesive described in Example 5 of International Publication No. 17 / 195400 was prepared and used instead of SX-ECA48, and electrolytic copper foil CF-T49A-SV-18 (18 μm thick) was attached to it and dried for one day to form the intermediate layer and pad. The sheet resistance of the pad in Example 8 was 0.02 Ω / □. The volume resistivity of the intermediate layer was 4.0 × 10⁻⁶. -3 The coefficient of glass was Ω·cm, and the glass transition temperature was 35°C. Furthermore, the pad thickness ratio to the conductive layer thickness was 6, as in Example 1, and the pad sheet resistance ratio to the conductive layer sheet resistance was 0.02, as in Example 1.

[0113] (Comparative Example 1) The process for patterning the conductive layer precursor layer was carried out in the same manner as in Example 1, except that a pattern corresponding to a 10cm x 1cm pad was added to the photomask in addition to the mesh-like pattern. The process up to the blackening treatment was performed. As a result, a pad directly connected to the conductive layer was formed within the same layer as the conductive layer, so the pad formation step in Example 1 was omitted. In this way, a three-dimensional conductive film for a transparent heater of Comparative Example 1 was manufactured. The sheet resistance of the pad in Comparative Example 1 was 0.1Ω / □.

[0114] (Comparative Example 2) In the conductive layer formation process in Comparative Example 1, after forming the conductive layer and pads with a copper mesh pattern, the conductive layer was masked, and only the pads were subjected to an additional plating treatment. Aside from this, the three-dimensional conductive film for the transparent heater in Comparative Example 2 was manufactured in the same manner as in Comparative Example 1. The sheet resistance of the pads in Comparative Example 2 was 0.05 Ω / □.

[0115] (Heater durability evaluation) For each of the three-dimensional conductive films for transparent heaters in Examples 1 to 7, Comparative Example 1, and Comparative Example 2, the resistance between a pad formed at one end of the conductive layer and a pad formed at the other end of the conductive layer was measured. Next, an external circuit for applying voltage was connected to the pads formed at one end of the conductive layer and the pads formed at the other end of the conductive layer. In this state, a voltage of 4V was applied to the three-dimensional conductive film for transparent heaters, and a current of 4A was passed through it, heating the conductive layer to 115°C for 500 hours. After 500 hours of heating, the resistance between the pads formed at one end of the conductive layer and the pads formed at the other end of the conductive layer was measured. Furthermore, the ratio of the resistance measured after heating to the resistance measured before heating was calculated as the resistance fluctuation rate.

[0116] Based on the resistance fluctuation rate calculated in this manner, the following evaluation results from S to D were given for each of the three-dimensional conductive films for transparent heaters in Examples 1 to 7, Comparative Example 1, and Comparative Example 2. An evaluation of S means that the film has excellent durability when used as a heater, an evaluation of A means that the film has good durability when used as a heater, an evaluation of B means that the film has sufficiently high durability when used as a heater, an evaluation of C means that the film has practically no problems with durability when used as a heater, and an evaluation of D means that there are problems with durability when used as a heater. In other words, the evaluations S, A, B, C, and D indicate increasing durability when used as a heater. S: Resistance fluctuation rate is 3% or less. A: Resistance fluctuation is greater than 3% but less than or equal to 5%. B: Resistance fluctuation is greater than 5% but less than or equal to 10%. C: Resistance fluctuation is greater than 10% but less than or equal to 15%. D: The resistance fluctuation is greater than 15%.

[0117] Table 1 below shows the evaluation results for Examples 1 to 7, Comparative Example 1, and Comparative Example 2. [Table 1]

[0118] Example 1 received an S rating for heater durability, demonstrating excellent heater durability. Example 8 received an A rating for heater durability, demonstrating good heater durability. Examples 2 and 3 received a B rating for heater durability, demonstrating sufficiently high heater durability. Examples 4 through 7 received a C rating for heater durability, demonstrating heater durability that poses no practical problems. On the other hand, both Comparative Example 1 and Comparative Example 2 received a D rating for heater durability, indicating that they have practical problems.

[0119] The three-dimensional conductive films for transparent heaters in Examples 1 to 8 all have an intermediate layer, whereas the three-dimensional conductive films for transparent heaters in Comparative Examples 1 and 2 do not have an intermediate layer. In Examples 1 to 8, even when the conductive layer is heated, the intermediate layer relieves the stress on the conductive layer and the pad, making it less likely for defects to occur at the joint between the conductive layer and the pad. On the other hand, in Comparative Examples 1 and 2, because there is no intermediate layer, when the conductive layer is heated, the stress on the conductive layer and the pad is not sufficiently relieved, making it more likely for failures such as tearing to occur at the joint between the conductive layer and the pad.

[0120] Comparing Example 1 and Example 2, the glass transition temperature of the intermediate layer in Example 1 is -60°C, while the glass transition temperature of the intermediate layer in Example 2 is a relatively high 45°C. Therefore, the intermediate layer in Example 2 is less susceptible to softening by heat and is considered inferior to the intermediate layer in Example 1 in its ability to relieve stress on the conductive layer and pad. This is likely why the heater durability evaluation for Example 1 was S, while the heater durability evaluation for Example 2 was B.

[0121] Comparing Example 1 and Example 3, the glass transition temperature of the organic polymer layer in Example 1 is 55°C, while the glass transition temperature of the organic polymer layer in Example 3 is a relatively high 79°C. Therefore, the organic polymer layer in Example 3 is less susceptible to softening by heat and is considered inferior to the organic polymer layer in Example 1 in its ability to relieve stress on the substrate and conductive layer. This is likely why the heater durability evaluation for Example 1 was S, while the heater durability evaluation for Example 3 was B.

[0122] Comparing Example 1 and Example 4, the three-dimensional conductive film for the transparent heater in Example 1 has an organic polymer layer, whereas the three-dimensional conductive film for the transparent heater in Comparative Example 4 does not have an organic polymer layer. Thus, in Example 4, the stress on the substrate and pad cannot be relieved by the organic polymer layer, which is why the heater durability evaluation for Example 1 was S, while the heater durability evaluation for Example 4 was C.

[0123] Comparing Example 1 and Example 5, the volume resistivity of the intermediate layer in Example 1 is 3.0 × 10⁻⁶. -3 In contrast to Ω·cm, the volume resistivity of the intermediate layer in Example 5 is 9.0 × 10⁻⁶. -3 The resistance is relatively high at Ω·cm. Therefore, the intermediate layer in Example 5 is considered to be inferior to the intermediate layer in Example 1 in its ability to conduct heat from the conductive layer, and requires more heat to soften. Consequently, the intermediate layer in Example 5 is considered to be less effective at relieving the stress on the conductive layer and pad than the intermediate layer in Example 1. This is why the heater durability evaluation for Example 5 was C compared to S for Example 1.

[0124] Comparing Example 1 and Example 6, the pad thickness ratio to the conductive layer thickness in Example 1 is 6, while the pad thickness ratio to the conductive layer thickness in Example 6 is a relatively low 1. Therefore, the pad in Example 6 is considered to be more prone to failure such as tearing when stress is applied compared to the pad in Example 1. This is likely why the heater durability evaluation for Example 1 was S, while the heater durability evaluation for Example 6 was C.

[0125] Comparing Example 1 and Example 7, the ratio of the sheet resistance of the pad to the sheet resistance of the conductive layer in Example 1 is 0.02, while the ratio of the sheet resistance of the pad to the sheet resistance of the conductive layer in Example 7 is 0.1, which is relatively high. Therefore, in Example 7, compared to Example 1, heat generated in the conductive layer is less easily conducted to the pad, and heat tends to accumulate at the junction between the conductive layer and the pad. Consequently, in Example 7, compared to Example 1, the expansion or contraction of the conductive layer is greater, and failures such as tearing are more likely to occur at the junction between the conductive layer and the pad. This is thought to be the reason why the heater durability evaluation for Example 7 was C compared to S for Example 1.

[0126] Comparing Example 1 and Example 8, the glass transition temperature of the intermediate layer in Example 1 is -60°C, while the glass transition temperature of the intermediate layer in Example 8 is a relatively high 35°C. Therefore, the intermediate layer in Example 8 is considered to be less susceptible to softening by heat and inferior in its ability to relieve stress on the conductive layer and pad compared to the intermediate layer in Example 1. This is likely why the heater durability evaluation for Example 1 was S, while the heater durability evaluation for Example 8 was A.

[0127] The present invention is basically configured as described above. Although the three-dimensional conductive film for transparent heaters of the present invention has been described in detail above, the present invention is not limited to the embodiments described above, and various improvements or modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0128] 11 Transparent heater three-dimensional conductive film, 12 Substrate, 13 Organic polymer layer, 14 Conductive layer, 15 Intermediate layer, 16 Pad, 17 Metal fine wire, 18 Aperture, CL Center line, P Pitch, W Line width.

Claims

1. circuit board and An organic polymer layer disposed on the substrate, An intermediate layer disposed on the organic polymer layer and comprising a conductive material and a resin material, A conductive layer disposed on the aforementioned organic polymer layer and formed of a metal mesh, The conductive layer has a pad that is electrically connected to it and also electrically connected to an external circuit, The conductive layer and the pad are electrically connected via the intermediate layer. The organic polymer layer is in contact with the intermediate layer and the conductive layer. Three-dimensional conductive film for transparent heaters.

2. The resin material contained in the intermediate layer has a glass transition temperature of 40°C or less, as described in claim 1, for a three-dimensional conductive film for a transparent heater.

3. The resin material contained in the intermediate layer has a glass transition temperature of 0°C or lower, as described in claim 2 for a three-dimensional conductive film for a transparent heater.

4. The three-dimensional conductive film for a transparent heater according to any one of Claims 1 to 3, wherein the intermediate layer has a volume resistivity of 5.0 × 10⁻³ Ω·cm or less.

5. The three-dimensional conductive film for a transparent heater according to any one of claims 1 to 4, wherein the intermediate layer is formed on the edges of the organic polymer layer and the conductive layer.

6. The organic polymer layer has a glass transition temperature of 60°C or less, as described in claim 1, for a three-dimensional conductive film for a transparent heater.

7. The three-dimensional conductive film for a transparent heater according to any one of claims 1 to 6, wherein the conductive layer is electrically connected to the pad via the intermediate layer by contacting a part of the intermediate layer.

8. The three-dimensional conductive film for a transparent heater according to any one of claims 1 to 7, wherein the pad is disposed on the intermediate layer.

9. The pad has a thickness of at least twice the thickness of the conductive layer, as described in any one of claims 1 to 8.

10. The pad has a sheet resistance of 1 / 10 or less of the sheet resistance of the conductive layer, as described in any one of claims 1 to 9.

11. The three-dimensional conductive film for a transparent heater according to claim 10, wherein the pad has a sheet resistance of 1 / 20 or less of the sheet resistance of the conductive layer.

12. The transparent three-dimensional conductive film for heater according to any one of claims 1 to 11, wherein the substrate and a part of the conductive layer have curved surfaces.

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