Method for manufacturing conductive base material, method for manufacturing electronic device, method for manufacturing electromagnetic wave shield film, and method for manufacturing planar heating element

Abstract

To provide a method for manufacturing a conductive base material capable of improving conductivity of a conductor.SOLUTION: A method for manufacturing a conductive base material 10 includes a step of forming a conductive particle-containing layer 4 on a base material 1 using a conductive composition containing conductive particles and a resin, a step of firing the conductive particle-containing layer 4, and a step of pressurizing the fired conductive particle-containing layer 4 to thereby form a conductor 5, in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a conductive substrate, a method for producing an electronic device, a method for producing an electromagnetic wave shielding film, and a method for producing a sheet heating element. [Background technology]

[0002] A known technique involves forming a pattern on a substrate using a conductive composition containing conductive particles and then heating the pattern to obtain a conductive pattern. This technique is thought to be applicable to printed electronics, which has been actively developed in recent years. Printed electronics is a technology that uses printing technology to form electronic circuits, sensors, elements, etc. on a substrate such as a film.

[0003] Patent Document 1 (JP 2014-017397 A) discloses that in order to obtain a low-cost metal thin film that has excellent adhesion and low volume resistivity, as well as a conductive pattern or the like that includes the metal thin film, the proportion of binder resin in a vertical cross section of the metal thin film containing metal fine particles and a binder resin is varied. It also discloses that in order to develop conductivity, a dispersion for a metal thin film on a substrate is irradiated with energy rays in such a way as to leave an unfixed region.

[0004] Patent Document 2 (JP 2021-77648 A) discloses that the mass ratio of the reducing agent and copper oxide during dispersion is controlled to obtain a conductive film with high dispersion stability as an ink, excellent storage stability, and low resistance on a substrate. It also discloses that a conductive pattern is obtained by irradiating the ink with xenon light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-017397 [Patent Document 2] Patent Publication No. 2021-77648 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the prior art disclosed in Patent Documents 1 and 2, the conductor is obtained by firing, but there is still room for improvement in terms of obtaining good conductivity of the conductor.

[0007] The present inventors have conducted extensive research into improving the conductivity of conductors and have found that the conductivity of a conductor can be improved by further applying pressure after the conductor is obtained by firing. Specifically, they discovered that the conductive particles enter gaps formed by the burning-off of the binder resin contained in the conductive composition by subsequent pressure application, bringing the conductive particles into close contact with each other, thereby increasing the conductivity, and have completed the present invention. [Means for solving the problem]

[0008] According to the present invention, the following techniques are provided.

[0009] [1] A step of forming a conductive particle-containing layer on a first substrate using a conductive composition containing conductive particles and a resin; firing the conductive particle-containing layer; forming a conductor by pressing the fired conductive particle-containing layer; A method for producing a conductive substrate, comprising: [2] A method for producing the conductive substrate according to [1], The method for producing a conductive substrate, wherein in the step of firing the conductive particle-containing layer, the conductive particle-containing layer is light-fired and / or thermally fired. [3] A method for producing the conductive substrate according to [1] or [2], The method for producing a conductive substrate, wherein the step of firing the conductive particle-containing layer comprises photo-firing using a xenon flash lamp. [4] A method for producing a conductive substrate according to any one of [1] to [3], The particle diameter D at which the cumulative frequency is 50% in a volume-based cumulative particle diameter distribution curve obtained when the particle diameter of the conductive particles is measured by a laser diffraction scattering method 50 is 0.5 to 100 μm. [5] A method for producing a conductive substrate according to any one of [1] to [4], A method for producing a conductive substrate, wherein the first substrate is flexible. [6] A method for producing a conductive substrate according to any one of [1] to [5], A method for producing a conductive substrate, wherein the first substrate is one or more types selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide, and paper. [7] A method for producing a conductive substrate according to any one of [1] to [4], After the step of forming the conductor, A method for producing a conductive substrate, comprising, in any order, a step of attaching the conductor to a second substrate and a step of peeling the conductor from the first substrate. [8] A method for producing the conductive substrate according to [7], A method for producing a conductive substrate, wherein the first substrate has higher heat resistance than the second substrate. [9] A method for producing a conductive substrate according to [7] or [8], The method for producing a conductive substrate, wherein the first substrate is one or more materials selected from the group consisting of metals, ceramics, and tempered glass.

[10] A method for producing a conductive substrate according to any one of [7] to [9], The method for producing a conductive substrate, wherein the first substrate has a liquid-repellent region and a non-liquid-repellent region on a surface on which the conductive particle-containing layer is formed.

[11] A method for producing a conductive substrate according to any one of [7] to

[10] , A method for producing a conductive substrate, wherein the second substrate is one or more types selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide, and paper.

[12] A method for producing a conductive substrate according to any one of [1] to

[11] , The method for producing a conductive substrate, wherein the step of forming the conductive particle-containing layer further comprises a step of removing a portion of the conductive particle-containing layer to form the conductive particle-containing layer into a desired shape.

[13] A method for producing a conductive substrate according to any one of [1] to

[12] , The method for producing a conductive substrate, wherein the step of forming the conductive particle-containing layer further comprises a step of drying a solvent contained in the conductive particle-containing layer.

[14] A method for producing a conductive substrate according to any one of [1] to

[13] , After the step of firing the conductive particle-containing layer and before the step of forming the conductor, A method for producing a conductive substrate, further comprising a step of permeating the conductive particle-containing layer with a component X for removing an oxide film on the surface of the conductive particles.

[15] A method for producing the conductive substrate according to

[14] , A method for producing a conductive substrate, wherein the component X includes at least one selected from the group consisting of an organic acid, a phosphorus oxoacid, and hydrazine or a derivative thereof.

[16] A method for producing a conductive substrate according to any one of [1] to

[15] , The method for producing a conductive substrate, wherein in the step of forming the conductor, the conductive particle-containing layer is pressurized while being heated.

[17] A method for producing a conductive substrate according to any one of [1] to

[16] , In the step of forming the conductor, the upper surface of the conductive particle-containing layer is covered with a member and then pressed.

[18] A method for producing a conductive substrate according to any one of [1] to

[17] , The method for producing a conductive substrate, wherein the conductor has a pattern structure.

[19] A method for producing an electronic device, comprising producing an electronic device using a conductive substrate obtained by the method for producing a conductive substrate according to any one of [1] to

[18] .

[20] A method for manufacturing the electronic device according to

[19] , The method for manufacturing an electronic device, wherein the electronic device is an RF tag.

[21] A method for producing an electromagnetic wave shielding film, comprising producing an electromagnetic wave shielding film using a conductive substrate obtained by the method for producing a conductive substrate according to any one of [1] to

[18] .

[22] A method for producing a sheet heating element, comprising producing a sheet heating element using a conductive substrate obtained by the method for producing a conductive substrate described in any one of [1] to

[18] . [Effects of the Invention]

[0010] According to the present invention, a method for producing a conductor substrate that can improve the conductivity of a conductor can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram illustrating a method for producing a conductive substrate according to the first embodiment. [Figure 2] FIG. 10 is a diagram illustrating a method for producing a conductive substrate according to a second embodiment. [Figure 3] 2A to 2C are enlarged views schematically illustrating a part of the manufacturing process of the conductive substrate according to the first and second embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, similar components are denoted by similar reference numerals and descriptions thereof will be omitted where appropriate. To avoid complexity, (i) when there are multiple identical components in the same drawing, only one of them is given a symbol, and not all of them, or (ii) particularly in Figure 2 and subsequent figures, components similar to those in Figure 1 are not given a symbol again. All drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0013] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0014] In the description of groups (atomic groups) in this specification, when a notation does not specify whether the group is substituted or unsubstituted, it encompasses both groups having no substituents and groups having a substituent. For example, the term "alkyl group" encompasses not only alkyl groups having no substituents (unsubstituted alkyl groups) but also alkyl groups having a substituent (substituted alkyl groups). In this specification, the term "(meth)acrylic" represents a concept that encompasses both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate." Unless otherwise specified, the term "organic group" as used herein means an atomic group obtained by removing one or more hydrogen atoms from an organic compound. For example, a "monovalent organic group" refers to an atomic group obtained by removing one hydrogen atom from any organic compound. In this specification, the term "electronic device" is used to encompass elements, devices, final products, etc. to which electronic engineering technology is applied, such as semiconductor chips, semiconductor elements, printed wiring boards, electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, and chemical batteries.

[0015] First Embodiment An example of a method for producing the conductive substrate 10 in the first embodiment will be described below with reference to Fig. 1. Fig. 1 and Fig. 2, which will be described later, are schematic diagrams showing cross sections of the conductive substrate 10 and the conductive substrate 20 when viewed from the front. Specifically, the cross sections refer to cross sections in a direction perpendicular to the direction in which the conductive pattern (conductor 5) extends when the conductive substrate 10 and the conductive substrate 20 are viewed in plan. In addition, in the plan view of the conductive substrate 10 and the conductive substrate 20, the conductive pattern corresponds to the circuit pattern.

[0016] The method for producing the conductive substrate 10 in the first embodiment includes the following steps: a step of forming a conductive particle-containing layer 4 on a substrate 1 using a conductive composition containing conductive particles and a resin; a step of firing the conductive particle-containing layer 4; a step of forming a conductor 5 by pressing the fired conductive particle-containing layer 4; Contains, in this order:

[0017] This can improve the conductivity of the conductor 5. That is, in this embodiment, the conductive particle-containing layer 4 is sintered, and the resin contained in the conductive particle-containing layer 4 is burned away, resulting in gaps that are formed, and the conductive particles are then allowed to enter by subsequent pressure application, allowing the conductive particles to come into close contact with each other, thereby improving the conductivity. Furthermore, it is believed that the conductive particles are sintered by the application of pressure, which can improve the conductivity of the conductor 5.

[0018] In the first embodiment, an example will be described in which the process further includes a step of infiltrating the conductive particle-containing layer 4 with a component X for removing an oxide film on the surface of the conductive particles, after the step of firing the conductive particle-containing layer 4 and before the step of forming the conductor 5; however, such a step is optional, and the order of steps is not limited to this.

[0019] Each step will be described in detail below.

[0020] [Step of forming conductive particle-containing layer 4] First, a conductive particle-containing layer 4 is formed on a substrate 1. In this embodiment, as shown in Fig. 1A, the conductive particle-containing layer 4 is formed on one surface of the substrate 1. The method for forming the conductive composition on the substrate 1 is not particularly limited, and known methods can be used. Specifically, the conductive particle-containing layer 4 may be provided over the entire surface of the substrate 1, or over only a portion of the surface of the substrate 1. In the former case, the conductive particle-containing layer 4 can be formed by coating using a device such as a blade coater, air knife coater, doctor coater, roll coater, bar coater (rod coater), or curtain coater. In the latter case, the conductive particle-containing layer 4 can be formed by various printing methods, such as screen printing, dispense printing, gravure printing, letterpress printing, lithographic printing (offset printing), inkjet printing, and transfer printing. By appropriately designing the "pattern" during printing, it is possible to produce a substrate with a pattern structure, such as a conductive film (circuit pattern) that can function as a circuit or a mesh pattern with electromagnetic wave shielding properties. When the conductive composition is provided over only a portion of the surface of the substrate 1, it is preferable that the printing "pattern" be appropriately designed depending on the intended use of the final conductive substrate 10. To prevent the conductive particle-containing layer 4 from being formed in any location other than the desired location on the substrate 1, for example, a film with holes cut out therein may be placed on the substrate 1, the conductive composition may be applied or printed on top of the film, and then the film may be removed.

[0021] The amount of the conductive composition used may be adjusted appropriately from the viewpoints of obtaining sufficient conductivity and ease of application or printing. Specifically, the thickness of the conductive particle-containing layer 4 is preferably 5 to 100 μm, and more preferably 10 to 50 μm.

[0022] 1B, in this step, the conductive particle-containing layer 4 formed on the substrate 1 may be partially removed to form the conductive particle-containing layer 4 into a desired shape. That is, a portion of the conductive particle-containing layer 4 may be removed to eliminate a portion where an excess conductive composition is printed by printing the conductive composition, i.e., a thickened pattern. The removal method is not particularly limited and may be any known method, such as ultraviolet laser etching, which can improve the precision and stability of the conductor pattern that is finally obtained.

[0023] Furthermore, in this step, if the conductive composition contains a solvent, the solvent contained in the conductive particle-containing layer 4 may be dried and removed. The conditions for the heat treatment are not particularly limited as long as the solvent is sufficiently dried, but are adjusted from the viewpoint of sufficiently drying the solvent and preventing deterioration of the conductive particles due to excessive heating. The heat treatment temperature is preferably 50 to 150°C, more preferably 80 to 120°C. The heat treatment time is preferably 1 to 60 minutes, more preferably 3 to 30 minutes. The heat treatment for drying the solvent can be carried out, for example, by applying hot air to the conductive particle-containing layer 4. Of course, the heat treatment may be carried out by other methods.

[0024] (Base material 1) The substrate 1 is usually in the form of a film, sheet or plate, and from the viewpoint of industrial productivity, the shape of the substrate 1 is preferably any of these.

[0025] In the first embodiment, the substrate 1 may be optically transparent or opaque. When the substrate 1 is optically transparent, it is possible to irradiate the substrate 1 with light such as ultraviolet light when photocuring the curable resin layer 2, which will be described later. When the substrate 1 is opaque, for example, it may be a foamed resin film or foamed resin sheet made from foamed polyethylene terephthalate (PET).

[0026] In the first embodiment, the substrate 1 is preferably flexible. By employing a flexible substrate 1, a flexible printed circuit (FPC) can be manufactured. By using a flexible substrate 1, it becomes easier to apply pressure using a "roll" in the "step of forming the conductor 5" described later. This is preferable from the viewpoint of mass production. Just to be clear, the substrate 1 may be a rigid substrate that does not have flexibility.

[0027] Although a general resin film can be used for the substrate 1, in consideration of cost and end use, it is preferable that the substrate 1 be at least one selected from the group consisting of polyesters such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), polyolefins such as polyethylene and polypropylene, polycarbonate, polyimide, and paper. The paper may be coated paper (paper whose surface is coated with a coating agent) or ordinary uncoated paper. Furthermore, in this embodiment, a conductive pattern with sufficiently low resistivity can be obtained without heating or by heating at a relatively low temperature in the "step of forming the conductor 5." Therefore, a substrate 1 with low heat resistance, such as polyester, polyolefin, or paper, can be used. On the other hand, when a substrate 1 with high heat resistance, such as polyimide, is used, high-temperature heating can be performed in the "step of forming the conductor 5," and the resistivity of the resulting conductive pattern can be further reduced. Furthermore, when photo-curing is performed using a xenon flash lamp in the "step of baking the conductive particle-containing layer 4," deterioration of the substrate 1 due to the xenon flash lamp can be reduced.

[0028] (Conductive particle containing layer 4) The conductive particle-containing layer 4 is formed using a conductive composition containing conductive particles and a resin.

[0029] 3A and 3B are enlarged views schematically illustrating a part of the manufacturing process of the conductive substrate in the first and second embodiments. Fig. 3A shows the conductive particle-containing layer 4 formed on the substrate 1, Fig. 3B shows the fired conductive particle-containing layer 4, and Fig. 3C shows the conductor 5 obtained by pressing the conductive particle-containing layer 4. As shown in FIG. 3a, in this step, resin 41 and conductive particles 42 are dispersed in the conductive particle-containing layer 4.

[0030] The thickness of the conductive particle-containing layer 4 can be appropriately set depending on the application, but is preferably 0.5 to 100 μm, more preferably 5 to 60 μm, and even more preferably 10 to 40 μm. By setting the thickness of the conductive particle-containing layer 4 to be equal to or greater than the above-mentioned lower limit, the conductivity of the final conductive pattern can be improved. On the other hand, by setting the thickness to be equal to or less than the above-mentioned upper limit, the entire conductive substrate 10 having the final conductive pattern can be made thinner. This is preferable, for example, from the viewpoint of reducing the size and weight of electronic devices.

[0031] (Conductive composition) The conductive composition used as the raw material for the conductive particle-containing layer 4 is preferably in a paste state at room temperature for ease of pattern formation.

[0032] The amount of the resin component in the conductive composition is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of the conductive particles. By setting the amount of resin component in the conductive composition to the above lower limit or more, it is possible to improve printability and pattern retention when applying the conductive composition. In addition, by preventing the conductive particles from settling in the conductive composition, it is possible to obtain a conductive particle-containing layer 4 having a desired shape while maintaining good conductivity. On the other hand, by setting the amount of the resin component in the conductive composition to the above upper limit or less, the conductivity of the finally obtained conductive pattern can be more easily increased.

[0033] In this embodiment, the resin contained in the conductive composition is one that can be burned away by firing. For example, the 5% weight loss temperature (°C) of the conductive composition is preferably lower than the 5% weight loss temperature (°C) of the substrate 1. In other words, the resin in the conductive composition is preferably one that is more easily burned away than the substrate 1.

[0034] The weight loss rate can be measured by using simultaneous thermogravimetry and differential thermal analysis to track the remaining weight of a sample when heated at a constant temperature increase rate. The temperature at which the weight has decreased by 5% from the initial value (100%) can be measured and used as the 5% weight loss temperature (°C).

[0035] Specific preferred examples of the resin contained in the conductive composition include polyvinylpyrrolidone, polyester, epoxy resin, (meth)acrylic resin, polyvinyl acetal, cellulose resin (such as ethyl cellulose), and phenol resin. Among these, resins that decompose at a relatively low temperature of 200 to 300°C are preferred, such as acrylic ethyl cellulose, because they are more likely to be burned away when photo-baking is performed in the "step of baking the conductive particle-containing layer 4." On the other hand, acrylic resins are preferred because they are more likely to be burned away when baked.

[0036] The conductive particles contained in the conductive composition preferably contain at least one element selected from the group consisting of silver and copper, from the viewpoints of availability and good conductivity. Specifically, the conductive particles preferably include at least one selected from the group consisting of particles primarily composed of silver and particles primarily composed of copper. Here, the expression "primarily composed of silver" means that the ratio of silver element to all constituent elements in the particles is preferably 50 mol% or more, more preferably 75 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. Similarly, the expression "primarily composed of copper" means that the ratio of copper element to all constituent elements in the particles is preferably 50 mol% or more, more preferably 75 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. It should be noted that the conductive particles may contain elements other than silver and copper, such as gold, aluminum, platinum, palladium, iridium, tungsten, nickel, tantalum, lead, and zinc, as long as the desired conductivity is achieved.

[0037] The conductive particles may contain two or more elements. For example, conductive particles in which the surfaces of copper particles are silver-plated (silver-coated copper particles) are preferably used in this embodiment. Silver-coated copper particles are particles whose main component is copper, and the surfaces of the copper particles are plated with silver in an amount of up to 35 mass% based on the total mass of the particles, for example.

[0038] Median diameter D of conductive particles 50 is preferably 0.5 to 100 μm, more preferably 0.6 to 50 μm, even more preferably 0.7 to 30 μm, and particularly preferably 0.7 to 20 μm. D 50 By making the value of the particle diameter equal to or larger than the lower limit, the number of grain boundaries between conductive particles per unit volume can be reduced, which is believed to lead to a further reduction in the resistivity of the resulting conductive pattern. D 50 By making the value of the conductive particles equal to or less than the upper limit, the "gaps" between the conductive particles are reduced, which is thought to lead to a smaller specific resistance of the resulting conductive pattern.

[0039] The median diameter D50 means the particle size at which the cumulative frequency is 50% in the volume-based cumulative particle size distribution curve obtained when particle sizes are measured by a laser diffraction scattering method.

[0040] Conductive particles can be purchased from, for example, DOWA Electronics Co., Ltd., Fukuda Metal Foil and Powder Co., Ltd. Two or more different conductive particles may be mixed together for the purpose of adjusting or optimizing the particle size distribution or for other purposes.

[0041] From the viewpoint of further reducing the resistivity of the finally obtained conductive pattern, the content of the conductive particles in the conductive composition is preferably 50 to 90 mass %, more preferably 55 to 85 mass %, and even more preferably 60 to 85 mass %. By setting the content of the conductive particles to the above lower limit or more, the conductivity is likely to be improved, while by setting the content of the conductive particles to the above lower limit or more, the conductive pattern is likely to be formed with high precision.

[0042] It is preferable that the conductive particles are not substantially sintered. In this embodiment, the conductive particles are usually sintered in the "step of forming the conductor 5" described later.

[0043] The conductive composition may further contain a solvent. When the conductive composition contains a solvent, the filling property and application property of the conductive composition are improved. The solvent typically contains an organic solvent. The solvent may contain water as long as the conductive particles can be appropriately dispersed in the solvent. The type of solvent is not particularly limited. Any solvent may be used as long as it does not substantially alter the components in the conductive composition. The amount of solvent used may be adjusted appropriately depending on the coating or printing method of the conductive composition. The amount of solvent used is, for example, 3 to 30 mass %, preferably 5 to 25 mass %, and more preferably 10 to 20 mass % of the total conductive composition.

[0044] From the viewpoint of improving the conductivity, it is preferable that the conductive composition is substantially free of a curable component. Moreover, from the viewpoint of improving the pattern formability, i.e., the printability and coatability of the conductive composition, the conductive composition may contain a binder or the like. The conductive composition may or may not contain various additive components found in conventional ink compositions and conductive pastes.

[0045] [Step of Firing the Conductive Particle-Containing Layer 4] Next, the conductive particle-containing layer 4 is baked, whereby the resin 41 contained in the conductive particle-containing layer 4 is burned off. That is, this is a step of burning off the resin 41 in the conductive particle-containing layer 4. Then, by subsequently applying pressure to the conductive particle-containing layer 4, the conductive particles in the conductive particle-containing layer 4 move and come into close contact with each other, thereby achieving good conductivity. Furthermore, the conductivity can be improved by sintering the conductive particles. It is sufficient that at least a portion of the resin contained in the conductive particle-containing layer 4 is burned away. For example, as shown in Fig. 1C, photo-baking may be performed by irradiating the upper surface of the conductive particle-containing layer 4 with light using a light source 6. In this case, as shown in Fig. 3b, the resin 41 on the upper side (the light source 6 side) of the conductive particle-containing layer 4 is burned away, and a void is generated in the region where the resin 41 was previously.

[0046] The burning away of the resin means that the resin is decomposed, reduced in molecular weight, and volatilized.

[0047] The conductive particle-containing layer 4 may be baked by either photo-baking or thermal baking, but photo-baking is preferred from the viewpoint of suppressing thermal deterioration of the substrate 1, and thermal baking is preferred when using a substrate 1 that easily absorbs light and generates heat. When baking a thermally decomposable resin, pressure may be applied along with heat.

[0048] The light source 6 used for photo-sintering is not particularly limited as long as it can sinter the resin and conductive particles, but a white light source that can provide continuous brightness over a wide wavelength range is preferred. Specific examples include one or more types selected from the group consisting of xenon flash lamps, xenon short arc lamps, ceramic xenon short arc lamps (UXR), krypton arc lamps, high-pressure mercury lamps, xenon mercury lamps, metal halide lamps, external electrode rare gas fluorescent lamps, halogen lamps, and deuterium lamps. Among these, photo-sintering using a xenon flash lamp is more preferred in terms of reducing the load on the substrate 1. Xenon flash lamps have a continuous spectrum in the wavelength range from 200 nm to 1000 mm. The amount of radiation energy is 10 J / cm 2 More than 25J / cm 2 Less than 15 J / cm is preferable. 2 More than 25J / cm 2 Less than 20 J / cm is more preferable. 2 More than 25J / cm 2 The irradiation time is preferably from 0.1 milliseconds to 10 milliseconds, more preferably from 1 millisecond to 8 milliseconds, and even more preferably from 2 milliseconds to 5 milliseconds.

[0049] In the light-baking, the upper surface of the conductive particle-containing layer 4, that is, the surface of the conductive particle-containing layer 4 opposite to the substrate 1, is preferably irradiated with light.

[0050] [Step for allowing ingredient X to penetrate] Furthermore, in this embodiment, a component X for removing an oxide film on the surface of the conductive particles may be further impregnated into the conductive particle-containing layer 4. This facilitates sintering of the conductive particles in the "step of forming a conductor 5" described later, and tends to further increase the conductivity of the finally obtained conductive pattern.

[0051] It is preferable that component X penetrates into the conductive composition through the gaps between the conductive particles. This tends to further increase the conductivity of the final conductive pattern. For this reason, this "step of penetrating component X" may be carried out simultaneously with the "step of forming conductor 5" described below.

[0052] For example, as shown in FIG. 1D, this can be done by dropping or spraying a liquid 7 containing a component X capable of removing an oxide film on the surface of the conductive particles, thereby contacting the conductive composition and preferably allowing it to penetrate.

[0053] The liquid 7 containing component X is preferably water in which component X is dissolved or dispersed. The use of water is preferable from the viewpoints of reducing the environmental load and process safety (non-flammability). Of course, an organic solvent in which component X is dissolved or dispersed can also be used. Instead of using a liquid 7 containing component X, component X in a gaseous state may be used. It is also possible to bring a sheet containing component X into contact with the conductive composition, preferably by applying pressure, to allow component X to penetrate. Specific examples of the sheet include paper or nonwoven fabric containing component X, and resin sheets having component X coated or printed on their surfaces.

[0054] Component X is not particularly limited as long as it is capable of removing the oxide film on the surface of the conductive particles. In this specification, "removal" of an oxide film includes not only the removal of the oxide itself present on the surface of a conductive particle, but also the case where the oxide undergoes a chemical change such as reduction, causing the oxide to return to a non-oxide state.

[0055] According to the inventors' findings, component X preferably contains at least one selected from the group consisting of organic acids, phosphorus oxoacids, and hydrazine or its derivatives, which are particularly suitable when the conductive particles contain copper or silver.

[0056] Examples of organic acids include carboxylic acids such as citric acid, formic acid, acetic acid, malonic acid, malic acid, tartaric acid, ascorbic acid, succinic acid, fumaric acid, and propionic acid. Specific examples of phosphorus oxoacids include phosphinic acid, phosphonic acid, diphosphorous acid, triphosphoric acid, and metatriphosphoric acid. Of these, phosphinic acid is particularly preferred. Examples of hydrazine or its derivatives include hydrazine itself; hydrazine salts such as hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, and hydrazine sulfate; and other compounds having an -NH-NH2 structure.

[0057] Additionally, from the viewpoint of removing an oxide film, a compound having a small pKa in water can be used as component X. Specifically, a compound having a pKa in water of -5.0 to 5.0 is preferred as component X, and a compound having a pKa of -4.0 to 4.5 is more preferred as component X. Incidentally, when component X is a polybasic acid, it is preferred that the smallest pKa among the multiple pKas is within the above range. Considering only the small pKa and the resulting ability to remove oxide films, it is conceivable to use an inorganic acid such as hydrochloric acid, nitric acid, or sulfuric acid as component X. However, in consideration of problems that may occur if the acid remains in the conductor 5, an organic acid is preferred as component X. The pKa value used here can be the value at room temperature (e.g., 25°C). However, from the viewpoint of the removability of the oxide film in the actual process, it can be said that it is preferable to use the pKa value at the temperature in the "step of forming the conductor 5."

[0058] Additionally, any compound capable of returning an oxide film to a non-oxidized state by a reduction reaction can also be used as component X. For example, a compound having an aldehyde group can be used as component X because it may be able to reduce an oxide.

[0059] Furthermore, compounds that have a small pKa in water and can return an oxidized film to a non-oxidized state through a reduction reaction are also preferably used as component X. An example of such a compound is formic acid. Formic acid has the advantage that it is easily volatile and therefore does not easily remain in the pattern.

[0060] In addition to the above, examples of component X include pyrogallol, phenidone, hydroquinone, and orthoaminophenol, which are known to function as reducing agents in the field of silver halide photography. When a conductive pattern having a lower resistivity is obtained when a certain compound is infiltrated into a conductive composition compared to when the compound is not infiltrated, the compound can be used as component X.

[0061] When a liquid in which component X is dissolved or dispersed is brought into contact with a conductive composition, the concentration of component X in the liquid may be adjusted as appropriate. The concentration may be adjusted from the viewpoints of allowing a sufficient amount of component X to penetrate into the conductive composition and reducing the amount of residual component X to suppress corrosion or deterioration of the conductive pattern. The concentration of component X in the liquid is, for example, 0.05 to 50 mol / L, preferably 0.1 to 40 mol / L, more preferably 0.1 to 30 mol / L, even more preferably 0.1 to 10 mol / L, and particularly preferably 0.15 to 5.0 mol / L. Of course, a liquid containing component X at a concentration lower than the concentrations shown here may be used, or a liquid containing component X at a concentration higher than the concentrations shown here (for example, saturation concentration) may be used.

[0062] [Step of forming conductor 5] Next, the fired conductive particle-containing layer 4 is pressurized to form a conductor 5. This can increase the conductivity of the conductor 5. That is, as shown in FIG. 3c, conductive particles 42 fill the voids created by the burned-off resin 41, thereby reducing the resistance. Furthermore, the conductive particles 42 become denser, improving the conductivity. Preferably, the conductive particles in the conductive composition are sintered by the pressure.

[0063] 1E, the pressure is preferably applied after the upper surface of the conductive particle-containing layer 4 is covered with a member 8. In addition, as one example, the pressure can be applied by sandwiching a laminate of the substrate 1, the conductive particle-containing layer 4, and the member 8 between two opposing rolls 9a and 9b and transporting the laminate between the two rolls. The member 8 is preferably a film-like material. In this embodiment, the liquid 7 containing the component X is present above the conductive particle-containing layer 4. In this case, it is believed that the component X penetrates into the conductive particle-containing layer 4 by pressurization, removing the oxide film of the conductive particles and simultaneously sintering the conductive particles.

[0064] There are several advantages to using the member 8 when applying pressure. Examples of the advantages include the following: Damage to the roll 9a can be suppressed. Also, it may be possible to suppress the conductive particle-containing layer 4 from being partially or entirely peeled off and adhering to the roll 9a. Since the roll 9a is prevented from coming into direct contact with the conductive particle-containing layer 4, unintended deformation or collapse of the conductive particle-containing layer 4 can be easily prevented. The member 8 functions as a buffer, making it easier to apply pressure uniformly to the conductive particle-containing layer 4. This leads to, for example, an improvement in the yield of the final conductive substrate 10. Furthermore, when the infiltration of component X and the application of pressure are performed simultaneously, applying pressure uniformly to the conductive particle-containing layer 4 is also preferable because it leads to the component X being infiltrated uniformly into the conductive particle-containing layer 4.

[0065] From one viewpoint, the material of the member 8 can be the same as that of the base material 1. That is, the member 8 can be preferably a polyester film such as a PET film. From another viewpoint, in order to prevent damage to the conductive particle-containing layer 4, an easily peelable film or release paper can be preferably used as the member 8. From another perspective, the member 8 may be made of a non-resin material such as aluminum foil.

[0066] On the other hand, in order to simplify the manufacturing process by reducing the amount of process materials and reduce waste, pressurization may be performed without using the member 8.

[0067] 1E shows an embodiment in which two opposing rolls 9a and 9b apply pressure to the conductive particle-containing layer 4. However, the conductive particle-containing layer 4 may also be pressurized by other methods. As one example, the laminate of the substrate 1, the conductive particle-containing layer 4, and the member 8 may be sandwiched between two flat plates and pressed (flat press). As another example, the laminate of the substrate 1, the conductive particle-containing layer 4, and the member 8 may be placed on a flat plate, and a roll may be applied from above to pressurize the conductive particle-containing layer 4 while rolling the roll. As yet another example, a roll may be applied from below the substrate 1, the conductive particle-containing layer 4, and the member 8 to pressurize the conductive particle-containing layer 4 while rolling the roll.

[0068] The pressure application is preferably performed while heating the conductive particle-containing layer 4. This tends to improve the conductivity of the conductive pattern. Preferably, the conductive particle-containing layer 4 is pressed at a pressure of 1 to 5000 MPa and heated at a temperature of 50 to 400°C. More preferably, the conductive particle-containing layer 4 is pressed at a pressure of 30 to 1000 MPa and heated at a temperature of 70 to 200°C. Even more preferably, the conductive particle-containing layer 4 is pressed at a pressure of 50 to 300 MPa and heated at a temperature of 80 to 150°C. As shown in FIG. 1D, when pressure is applied using two opposing rolls 9a and 9b, it is preferable to use rolls with built-in heaters that can adjust the temperature.

[0069] [Other optional processes] The method for producing the conductive substrate 10 of this embodiment may include steps other than the steps described above. One example is a step of removing component X remaining on the surface or inside the obtained conductive pattern after pressing. Specific examples include a step of immersing the obtained conductive substrate 10 in a liquid (water or an organic solvent) that can dissolve or disperse component X, or a step of pouring a liquid (water or an organic solvent) onto the surface of the conductive pattern to wash away the remaining component X. Another possible step is to vaporize and remove the remaining component X by heating the obtained conductive substrate 10 at a temperature that does not damage the substrate 1.

[0070] In this manner, a conductive substrate 10 having a conductor 5 disposed on a substrate 1 can be produced as shown in FIG. 1F.

[0071] Second Embodiment Next, a method for producing the conductive substrate 20 according to the second embodiment will be described with reference to FIG. In the second embodiment, a case will be described in which, after the step of forming the conductor 5 of the first embodiment, the step of attaching the conductor 5 to a substrate 22 (second substrate) and the step of peeling the conductor 5 from the substrate 21 (first substrate) are further included, in no particular order. Hereinafter, descriptions of the same configurations and effects as those of the first embodiment will be omitted as appropriate.

[0072] As shown in FIG. 2, the method for producing the conductive substrate 20 according to the second embodiment includes the following steps: A step of forming a conductive particle-containing layer 4 on a substrate 21 (first substrate) using a conductive composition containing conductive particles and a resin; a step of firing the conductive particle-containing layer 4; a step of forming a conductor 5 by pressing the fired conductive particle-containing layer 4; and The method includes, in any order, a step of attaching the conductor 5 to the substrate 22 (second substrate) and a step of peeling the conductor 5 from the substrate 21.

[0073] This improves the conductivity of the conductor 5. Furthermore, in the second embodiment, the substrate 21 is peeled off after the firing process, so the type of substrate 21 is not limited, and the degree of freedom in design is increased. Furthermore, the substrate 22 constituting the finally obtained conductive substrate 20 is not damaged by firing, so the dimensional stability of the conductive substrate 20 can be improved. Furthermore, since the substrate 21 is peeled off later, the substrate 21 can be reused in the manufacturing process of other conductive substrates.

[0074] The method for producing the conductive substrate 20 in the second embodiment will be described below, focusing on the differences from the first embodiment.

[0075] [Step of forming conductive particle-containing layer 4] First, in the same manner as in the first embodiment, a conductive particle-containing layer 4 is formed on a substrate 21 (FIG. 2A).

[0076] (Base material 21) The substrate 21 is usually in the form of a film, sheet, cylinder, or plate. From the viewpoint of industrial productivity, any of these shapes is preferred for the substrate 1. Since the substrate 21 is later peeled off from the conductor 5, the substrate 21 can be reused in the manufacturing process of other conductive substrates.

[0077] In the second embodiment, the material of the substrate 21 (first substrate) is not particularly limited as long as it can form the conductive particle-containing layer 4, and the substrate 21 does not constitute the final conductive substrate 20. For example, the substrate 21 may not be flexible. Furthermore, since the substrate 21 will be peeled off from the conductor 5 later, it is preferable that the substrate 21 has good peelability from the conductor 5. The substrate 21 may have higher heat resistance than the substrate 22 described below. For example, the substrate 21 may be made of one or more materials selected from the group consisting of metal, ceramic, and tempered glass. This makes it easier to form the conductive particle-containing layer 4. The substrate 21 may be optically transparent or opaque. When the substrate 21 is optically transparent, it is possible to irradiate the substrate 2 with light such as ultraviolet light from the substrate 1 side during photo-curing of the curable resin layer 2, which will be described later. When the substrate 21 is opaque, it may be, for example, a foamed resin film or foamed resin sheet made from foamed polyethylene terephthalate (PET).

[0078] The term "heat resistance" means that at least one of decomposition, deterioration, deformation, and softening due to heat is relatively small.

[0079] The substrate 21 preferably has a liquid-repellent region and a non-liquid-repellent region on the surface on which the conductive particle-containing layer 4 is formed, and the conductive particle-containing layer 4 is preferably formed in the non-liquid-repellent region. This suppresses the conductive composition from spreading when applied, and can prevent the conductive composition from being applied to an unintended region and forming an unintended conductive particle-containing layer 4. Furthermore, if the conductive composition has sufficient fluidity, the conductive composition can be applied to the entire surface of the substrate 1, and due to the difference in surface condition between the water-repellent area and the non-water-repellent area, the conductive composition will naturally collect on the non-water-repellent area, thereby obtaining a conductive particle-containing layer 4 with the desired pattern.

[0080] The term "liquid repellency" refers to the property of removing the conductive composition from the surface of the substrate 1. The liquid-repellent area can be obtained by chemical processing, such as applying a fluororesin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) as a liquid-repellent material onto the substrate 21; or by physical processing, such as microfabrication (adjusting the surface roughness and shape of the substrate 1), and surface modification by ultraviolet irradiation.

[0081] The liquid-repellent area and the non-liquid-repellent area do not have to be continuous, and may be partially discontinuous. Furthermore, there may be one or more liquid-repellent areas and one or more non-liquid-repellent areas. The non-liquid-repellent area may be a lyophilic area.

[0082] [Step of Firing the Conductive Particle-Containing Layer 4] Next, the conductive particle-containing layer 4 is fired in the same manner as in the first embodiment (FIG. 2B). In the second embodiment, the base material 21 is later peeled off from the conductor 5 and does not constitute the conductive base material 20, so firing can be performed without considering the thermal history of the conductive base material 20. In addition, the degree of freedom in designing the material of the base material 21 is also increased.

[0083] [Step for allowing ingredient X to penetrate] Next, as shown in FIG. 2C, component X is permeated in the same manner as in the first embodiment.

[0084] [Step of forming conductor 5] Next, as shown in FIG. 2D, the fired conductive particle-containing layer 4 is pressed to form a conductor 5 in the same manner as in the first embodiment. In the second embodiment, when the substrate 21 is cylindrical, the roll 9b may be used as the substrate 21. That is, the conductive particle-containing layer 4 may be formed directly on the roll 9b, and after the conductive particle-containing layer 4 is baked, the conductive particle-containing layer 4 may be pressed together with the roll 9a. Furthermore, as described above, the substrate 21 is later peeled off from the conductor 5 and does not constitute the conductive substrate 20, so pressure can be applied without considering the pressure history on the conductive substrate 20. Furthermore, the degree of freedom in designing the material of the substrate 21 is also increased.

[0085] [Step of attaching the conductor 5 to the substrate 22] In the second embodiment, the obtained conductor 5 is further attached to a substrate 22. There are no particular limitations on the attachment method, as long as it can exhibit the functions of the finally obtained conductive substrate 20. For example, a pressure-sensitive adhesive or a curable resin may be used as the adhesive member. The curable resin has the property of being cured by at least one of light and heat, and is cured after being attached to the conductor 5. 2F, in this embodiment, an adhesive is used to form an adhesive layer 12 on a substrate 22, and the substrate 22 is attached to a conductor 5 via the adhesive layer 12. Any known adhesive can be used as the adhesive.

[0086] (Base material 22) The base material 22 may be the same as the base material 1 described in the first embodiment, and the same effects can be obtained. In particular, since the base material 22 is not subjected to the above-mentioned baking or pressure application, it may be made of a material with relatively low heat resistance and pressure resistance, such as polyester, polyolefin, paper, or polycarbonate. In the second embodiment, the substrate 21 and the substrate 22 may be the same as each other or may be different.

[0087] [Step of Peeling the Conductor 5 and the Base Material 21] The conductor 5 is then peeled off from the substrate 21. The peeling method is not particularly limited, and any known method can be used.

[0088] In this way, a conductive substrate 20 is obtained in which the conductor 5 is laminated on the base material 22 via the adhesive layer 12 (FIG. 2G).

[0089] The order of the "step of attaching the conductor 5 to the substrate 22" and the "step of peeling the conductor 5 from the substrate 21" is not limited to this.

[0090] In addition, the method for manufacturing the conductive substrate 20 of the second embodiment can employ the same configuration as that described for the method for manufacturing the conductive substrate 10 of the first embodiment, and similar effects can be obtained.

[0091] <Electronic device manufacturing method> The conductive substrate 10 and conductive substrate 20 obtained as described above can be used to manufacture electronic devices.

[0092] Here, some examples of electronic devices will be described. However, it should be noted that the electronic devices including the conductive substrate 10 and the conductive substrate 20 obtained by the manufacturing method of this embodiment are not limited to these examples. Sensors: For example, the conductive substrate 10 and conductive substrate 20 obtained by the manufacturing method of this embodiment can be applied to conductive members / circuits in sensors such as pressure-sensitive sensors and vital sensors. Solar cells: For example, the conductive base material 10 and the conductive base material 20 obtained by the manufacturing method of this embodiment can be applied to current collecting wiring of solar cells. Membrane switch: A membrane switch is a thin sheet-like switch made by printing circuits and contacts on a film and then laminating the printed film. The manufacturing method of the conductive substrate 10 and the conductive substrate 20 of this embodiment can be applied to form the circuits and contacts. Touch sensor / touch panel: For example, the manufacturing method of the conductive substrate 10 and the conductive substrate 20 of the present embodiment can be applied to form lead wiring in a touch sensor / touch panel. It is also conceivable to apply the manufacturing method of the conductive substrate 10 and the conductive substrate 20 of the present embodiment to form transparent electrodes in a touch sensor / touch panel. Flexible substrate: Conventionally, a circuit is formed by first coating the entire surface of a flexible film with a metal film and then removing unnecessary portions of the metal film using chemicals. Instead of this conventional method, it is possible to form a circuit using the manufacturing method of the conductive substrate 10 and the conductive substrate 20 of this embodiment.

[0093] In particular, in electronic devices where circuits have conventionally been formed using conductive paste, by using the manufacturing method of this embodiment to form circuits, the resistivity of the circuits can be reduced, and improved performance of the electronic devices can be expected.

[0094] A particularly preferred example of the electronic device is an RF tag. That is, the method for producing a conductive substrate of this embodiment is preferably used to produce a conductive circuit such as an antenna portion of an RF tag. For the specific structure of the RF tag, reference can be made to, for example, Japanese Patent Application Laid-Open No. 2003-332714 and Japanese Patent Application Laid-Open No. 2020-46834.

[0095] <Method of manufacturing electromagnetic wave shielding film> As an application other than electronic devices, it is conceivable to manufacture an electromagnetic wave shielding film by the manufacturing method of the conductive substrate 10 and the conductive substrate 20 of the present embodiment. Specifically, in the lamination step, an electromagnetic wave shielding film can be manufactured by printing the conductive composition in a pattern specific to the electromagnetic wave shielding film (such as a mesh pattern).

[0096] <Method of manufacturing a sheet heating element> As another application, the method for manufacturing the conductive substrate 10 and the conductive substrate 20 according to the present embodiment may be used to manufacture a sheet heating element. A sheet heating element is an element that generates heat by passing an electric current through electrical wiring provided on a substrate. A specific example of a sheet heating element is a sheet heating element for preventing fogging or cold weather, such as on the rear window of a passenger vehicle.

[0097] <Conductive substrate 10 and article for manufacturing conductive substrate 20> For example, an article comprising a substrate 1, a curable resin layer 2 provided on the surface of the substrate 1, and a conductive composition containing conductive particles arranged on the surface of the curable resin layer 2, as shown in Figure 2D, can be considered a "semi-finished product" for producing the conductive substrate 10 and the conductive substrate 20.

[0098] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Explanation of symbols]

[0099] 1 Base material 21 Base material 22 Base material 4 Conductive particle-containing layer 41 Resin 42 Conductive particles 5 Conductors 6 light source 7 liquid 8. Components 9a Roll 9b Roll 12 Adhesive layer 10 Conductive substrate 20 Conductive substrate

Claims

1. forming a conductive particle-containing layer on a first substrate using a conductive composition containing conductive particles and a resin; firing the conductive particle-containing layer; forming a conductor by pressing the fired conductive particle-containing layer; A method for producing a conductive substrate, comprising:

2. A method for producing the conductive substrate according to claim 1, The method for producing a conductive substrate, wherein in the step of firing the conductive particle-containing layer, the conductive particle-containing layer is light-fired and / or thermally fired.

3. The method for producing the conductive substrate according to claim 2, The method for producing a conductive substrate, wherein the step of firing the conductive particle-containing layer comprises photo-firing using a xenon flash lamp.

4. A method for producing the conductive substrate according to claim 1 or 2, The particle diameter D at which the cumulative frequency is 50% in a volume-based cumulative particle diameter distribution curve obtained when the particle diameter of the conductive particles is measured by a laser diffraction scattering method. ５０ is 0.5 to 100 μm.

5. A method for producing the conductive substrate according to claim 1 or 2, The method for manufacturing a conductive substrate, wherein the first substrate is flexible.

6. A method for producing the conductive substrate according to claim 1 or 2, The method for producing a conductive substrate, wherein the first substrate is one or more types selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide, and paper.

7. A method for producing the conductive substrate according to claim 1 or 2, After the step of forming the conductor, A method for producing a conductive substrate, comprising, in any order, a step of attaching the conductor to a second substrate and a step of peeling the conductor from the first substrate.

8. The method for producing the conductive substrate according to claim 7, The method for manufacturing a conductive substrate, wherein the first substrate has higher heat resistance than the second substrate.

9. The method for producing the conductive substrate according to claim 7, The method for producing a conductive substrate, wherein the first substrate is one or more materials selected from the group consisting of metals, ceramics, and tempered glass.

10. The method for producing the conductive substrate according to claim 7, The method for producing a conductive substrate, wherein the first substrate has a liquid-repellent region and a non-liquid-repellent region on a surface on which the conductive particle-containing layer is formed.

11. The method for producing the conductive substrate according to claim 7, The method for producing a conductive substrate, wherein the second substrate is one or more selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide, and paper.

12. A method for producing the conductive substrate according to claim 1 or 2, The method for producing a conductive substrate, wherein the step of forming the conductive particle-containing layer further comprises a step of removing a portion of the conductive particle-containing layer to form the conductive particle-containing layer into a desired shape.

13. A method for producing the conductive substrate according to claim 1 or 2, The method for producing a conductive substrate, wherein the step of forming the conductive particle-containing layer further comprises a step of drying a solvent contained in the conductive particle-containing layer.

14. A method for producing the conductive substrate according to claim 1 or 2, After the step of firing the conductive particle-containing layer and before the step of forming the conductor, The method for producing a conductive substrate further comprises a step of infiltrating the conductive particle-containing layer with a component X for removing an oxide film on the surface of the conductive particles.

15. The method for producing the conductive substrate according to claim 14, A method for producing a conductive substrate, wherein the component X includes at least one selected from the group consisting of an organic acid, a phosphorus oxoacid, and hydrazine or a derivative thereof.

16. A method for producing the conductive substrate according to claim 1 or 2, The method for producing a conductive substrate, wherein in the step of forming the conductor, the conductive particle-containing layer is pressurized while being heated.

17. A method for producing the conductive substrate according to claim 1 or 2, In the step of forming the conductor, the upper surface of the conductive particle-containing layer is covered with a member and then pressed.

18. A method for producing the conductive substrate according to claim 1 or 2, The method for producing a conductive substrate, wherein the conductor has a pattern structure.

19. A method for producing an electronic device, comprising producing an electronic device using a conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

20. 20. The method of manufacturing an electronic device according to claim 19, comprising: The method for manufacturing an electronic device, wherein the electronic device is an RF tag.

21. A method for producing an electromagnetic wave shielding film, comprising producing an electromagnetic wave shielding film using the conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

22. A method for producing a sheet heating element, comprising producing a sheet heating element using a conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

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