Method for producing conductive substrate, method for producing electronic device, method for producing electromagnetic wave shielding film, method for producing planar heating element, and conductive composition

Abstract

A method for producing a conductive substrate, the method comprising: a coating step for applying a conductive composition containing conductive particles on a substrate to form a coating layer; and a conductive film formation step for forming a conductive film by at least pressurizing the coating layer. Here, in a volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by a laser diffraction scattering method, when the particle size at a cumulative frequency of 50% is D50, the particle size at a cumulative frequency of 10% is D10, and the particle size at a cumulative frequency of 90% is D90, the following (a) and (b) are satisfied. (a) The D50 is 0.6 to 50 [mu] m. (b) (D90-D50) / D50 is in the range of 0.55 to 3.0.

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, a method for producing a planar heating element, and a conductive composition. Background Art

[0002] There is known a technique of forming a conductive substrate having a conductive film by coating a conductive composition containing conductive particles on a substrate to form a coating layer, and heating and pressing the coating layer.

[0003] As an example, the example of Patent Document 1 describes a process in which silver fine particles having an average primary particle size of 7 nm are dispersed in water / ethylene glycol, applied to a PET film to form a coating film, and the coating film is heated and pressurized at 150° C. to form a conductive layer.

[0004] As another example, the embodiment of Patent Document 2 records that a copper particle dispersion (copper nano-ink) having a median particle size of about 40 nm, a dispersion medium and a dispersant is spin-coated on a glass substrate to form a coating film, which is then calcined to form a conductive film.

[0005] As another example, Patent Document 3 describes that a conductive ink composition containing (A) a hydroxycarboxylic acid, (B) a nitrogen-containing compound, (C) copper particles, and (D) a dispersion medium is applied on a substrate to form a coating film, and the coating film is treated to form a conductive layer.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6181608

[0009] Patent Document 2: Japanese Patent Application Publication No. 2021-044308

[0010] Patent Document 3: Japanese Patent Application Publication No. 2017-191723 Summary of the invention

[0011] When a conductive film is formed using a conductive composition containing conductive particles, it is preferred that the resistivity of the conductive film be as low as possible. In addition, it is more preferred that a conductive film with a low resistivity can be produced by a simple and uncomplicated process.

[0012] The present invention has been made in view of the above circumstances. One object of the present invention is to provide a method for producing a conductive substrate capable of forming a conductive film having a low resistivity.

[0013] The present inventors have completed the invention provided below to solve the above-mentioned problems. 1.

[0015] A method for manufacturing a conductive substrate comprises the following steps:

[0016] a coating step of coating a conductive composition containing conductive particles on a substrate to form a coating layer; and

[0017] A conductive film forming step of at least pressing the coating layer to form a conductive film;

[0018] The above-mentioned conductive particles satisfy the following conditions.

[0019] (condition)

[0020] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the conductive particles by a laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 , the following (a) and (b) are satisfied.

[0021] (a)D 50 0.6~50μm.

[0022] (b)(D 90 -D 50 ) / D 50 It is 0.55~3.0. 2.

[0024] The method for producing a conductive substrate according to 1., wherein:

[0025] The above-mentioned substrate has flexibility. 3.

[0027] The method for producing a conductive substrate according to 1. or 2., wherein:

[0028] In the conductive film forming step, the coating layer is heated and pressurized. 4.

[0030] The method for producing a conductive substrate according to any one of 1. to 3., wherein

[0031] Further satisfying the following (c).

[0032] (c)(D 50 -D 10 ) / D 50 It is 0.4~0.8. 5.

[0034] The method for producing a conductive substrate according to any one of 1. to 4., wherein

[0035] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the conductive particles by a laser diffraction scattering method, the particle size at which the cumulative frequency is 95% is defined as D 95 When D 95 1.5~100μm. 6.

[0037] The method for producing a conductive substrate according to any one of 1. to 5., wherein

[0038] The amount of the binder in the total non-volatile components of the conductive composition is 5% by mass or less. 7.

[0040] The method for producing a conductive substrate according to any one of 1. to 6., wherein

[0041] The substrate is at least one selected from polyester, polyolefin, polyimide and paper. 8.

[0043] The method for producing a conductive substrate according to any one of 1. to 7., wherein

[0044] The conductive film forming step includes a rolling step of conveying the substrate provided with the coating layer between two opposing rollers. 9.

[0046] The method for producing a conductive substrate according to 8., wherein:

[0047] In the rolling step, the roll of the two rolls with which the coating layer contacts is not heated or is heated to 400° C. or less. 10.

[0049] The method for producing a conductive substrate according to 8. or 9., wherein:

[0050] In the roll pressing step, a pressure of 10 MPa or more is applied to the substrate provided with the coating layer. 11.

[0052] The method for producing a conductive substrate according to any one of 1. to 7.,

[0053] The conductive film forming step includes placing the substrate provided with the coating layer on a flat plate or on the flat surface of a table having a flat surface, and at least pressurizing the coating layer from above using a roller. 12.

[0055] The method for producing a conductive substrate according to any one of 1. to 7., wherein

[0056] The conductive film forming step includes a step of sandwiching the substrate provided with the coating layer between the first flat surface of a first pressing member having a first flat surface and the second flat surface of a second pressing member having a second flat surface. 13.

[0058] The method for producing a conductive substrate according to any one of 1. to 12., wherein

[0059] The conductive film has a pattern structure. 14.

[0061] A method for producing an electronic device, comprising producing the electronic device using a conductive substrate obtained by the method for producing a conductive substrate according to any one of 1. to 13. 15.

[0063] The method for manufacturing an electronic device according to 14., wherein:

[0064] The above-mentioned electronic device is an RF tag. 16.

[0066] 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 13. 17.

[0068] A method for producing a planar heat generating body, comprising producing the planar heat generating body using a conductive substrate obtained by the method for producing a conductive substrate according to any one of 1. to 13. 18.

[0070] A conductive composition containing conductive particles is applied on a substrate to form a coating layer and the coating layer is at least pressurized to form a conductive film.

[0071] The above-mentioned conductive particles satisfy the following conditions.

[0072] (condition)

[0073] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the conductive particles by a laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 , the following (a) and (b) are satisfied.

[0074] (a)D50 0.6~50μm.

[0075] (b)(D 90 -D 50 ) / D 50 It is 0.55~3.0. 19.

[0077] The conductive composition according to 18., wherein

[0078] The said electroconductive particle further satisfies the following (c).

[0079] (c)(D 50 -D 10 ) / D 50 It is 0.4~0.8. 20.

[0081] The conductive composition according to 18. or 19., wherein

[0082] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the conductive particles by a laser diffraction scattering method, the particle size at which the cumulative frequency is 95% is defined as D 95 When D 95 1.5~100μm. twenty one.

[0084] The conductive composition according to any one of 18. to 20., wherein

[0085] The amount of the binder in the total non-volatile components was 5% by mass.

[0086] According to the present invention, a conductive film having a low resistivity can be formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 It is a figure for demonstrating the coating process.

[0088] Figure 2 It is a diagram for explaining the conductive film forming step.

[0089] Figure 3 It is a diagram for explaining the conductive film forming step.

[0090] Figure 4 It is a diagram for explaining the conductive film forming step.

[0091] Figure 5 This is a diagram for illustrating a specific aspect of the roughening treatment of the screen used in the examples. DETAILED DESCRIPTION

[0092] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0093] In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0094] In order to avoid complexity, (i) when there are multiple identical components in the same figure, sometimes only one of them is given a symbol, and not all of them are given symbols; (ii) especially Figure 2 Later, sometimes it is not right to Figure 1 The same elements are re-signed.

[0095] All drawings are for illustration purposes only. The shapes, dimensional ratios, etc. of the components in the drawings do not necessarily correspond to actual items.

[0096] In the present specification, unless otherwise specified, the notation "X to Y" in the description of a numerical range means greater than or equal to X and less than or equal to Y. For example, "1 to 5 mass %" means "1 mass % or more and 5 mass % or less".

[0097] <Method for producing conductive substrate>

[0098] The method for manufacturing the conductive substrate of this embodiment includes the following steps:

[0099] a coating step of coating a conductive composition containing conductive particles on a substrate to form a coating layer; and

[0100] In the conductive film forming step, the coated layer is at least pressurized to form a conductive film.

[0101] Hereinafter, each step will be described in detail with reference to the drawings.

[0102] ( Figure 1 : Coating process)

[0103] In the coating step, a conductive composition containing conductive particles is coated on the substrate 1 (on at least one surface of the substrate 1 ) to provide the coating layer 3 .

[0104] In this case, the conductive particles contained in the conductive composition satisfy the following conditions.

[0105] (condition)

[0106] In the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by the laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 , the following (a) and (b) are satisfied.

[0107] (a)D 50 0.6~50μm.

[0108] (b)(D 90 -D 50 ) / D 50 It is 0.55~3.0.

[0109] As described later, the coating layer 3 becomes a conductive film by at least applying pressure. The resistivity of the conductive film can be reduced by the conductive particles contained in the conductive composition satisfying the above (conditions). The reason can be explained as follows. It should be noted that the following description contains speculations, and the present invention should not be interpreted as being limited by the following description.

[0110] In the prior art of forming a conductive substrate with a conductive film by coating a conductive composition containing conductive particles on a substrate to provide a coating layer and heating and pressurizing the coating layer, nano-sized conductive particles are mostly used. This is because when the size of the conductive particles is about 100nm or less, it has a sintering promoting effect. Specifically, when the size of the conductive particles is about 100nm or less, the free energy of the entire system increases due to the increase in surface area, and the conductive particles are easily sintered to each other in order to reduce their free energy. This can be explained based on physical and chemical theory.

[0111] However, when nano-sized metal particles are used, the number of grain boundaries between conductive particles per unit volume tends to be extremely large. The presence of grain boundaries causes an increase in electrical resistance.

[0112] Therefore, the present inventors decided to use submicron to micron-sized conductive particles instead of nano-sized conductive particles. Specifically, the particle size D having a cumulative frequency of 50% in the volume-based cumulative particle size distribution curve obtained when the particle size is measured by laser diffraction scattering method is used. 50 Conductive particles with a diameter of 0.6 to 50 μm. Incidentally, conductive particles with a diameter of submicron to micron order also have the advantage of being cheaper and more readily available than nano-sized particles.

[0113] However, when the ratio of coarse particles in the conductive particles is large, even if D 50 If the conductive particles are 0.6 to 50 μm, "gaps" are likely to form between the conductive particles, resulting in a risk of increasing the resistance of the conductive film. 50 , and it can be said that D 50 The relative D 90 Size (D 90 -D 50 ) / D 50 The value of is also below 3.0.

[0114] By the way, (D 90 -D 50 ) / D 50 The lower limit of the value of 0.6 is a value set in consideration of the particle size distribution of conductive particles that are easily available industrially.

[0115] Hereinafter, the coating step will be described in more detail.

[0116] · About the particle size distribution of conductive particles

[0117] As mentioned above, for conductive particles, D 50 0.6~50μm, (D 90 -D 50 ) / D 50 It can be 0.55 to 3.0.

[0118] D 50 It is preferably 0.6 to 30 μm, more preferably 0.7 to 20 μm, and even more preferably 0.7 to 15 μm.

[0119] (D 90 -D 50 ) / D 50 It is preferably 0.55 to 2.5, more preferably 0.55 to 2.

[0120] It is preferable that the conductive particles further satisfy the following (c).

[0121] (c)(D 50 -D 10 ) / D 50 It is 0.4 to 0.8, more preferably 0.4 to 0.7, and further preferably 0.5 to 0.7.

[0122] In order to improve the conductivity of the conductive film obtained by at least pressurizing the coating film containing conductive particles, it is preferred to increase the density of the conductive particles in the coating film. As a method for this purpose, it is considered to adjust and optimize the particle size distribution of the conductive particles so that an appropriate amount of particles with smaller particle sizes exist in the "gaps" between particles with larger particle sizes. The above (c) can be interpreted as corresponding to the presence of an appropriate amount of particles with a particle size of the central value D in the conductive particles. 50 The particles nearby are relatively smaller in size.

[0123] In addition, it is also considered that the inclusion of "a certain amount" of submicron-sized conductive particles can provide a certain degree of sintering acceleration effect.

[0124] As another viewpoint, in the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by the laser diffraction scattering method, the particle size at which the cumulative frequency is 95% is defined as D 95 When D95 The thickness is preferably 1.5 to 100 μm, more preferably 1.5 to 50 μm, and still more preferably 1.5 to 30 μm.

[0125] As described above, when the ratio of coarse particles in the conductive particles is large, even if D 50 If the diameter is 0.6 to 50 μm, "gaps" are likely to form between the conductive particles, resulting in a risk of increasing the resistance of the conductive film. 90 -D 50 ) / D 50 The value of must be less than 3.0, but in addition, it is considered that D 95 When the value is not too large, "gaps" between the conductive particles are less likely to be generated, and as a result, the resistivity of the conductive film obtained becomes smaller.

[0126] For a certain conductive particle D 50 If the conductive particles are purchased and the volume-based cumulative particle size distribution curve of the conductive particles is provided by the purchase source, D is calculated based on the curve. 50 Equal value. 50 When the value is equal to itself, this value may be adopted.

[0127] On the other hand, in the case where it is not possible to know D 50 When the values ​​are equal, the particle size of the conductive particles is measured by a laser diffraction scattering method to obtain a volume-based cumulative particle size distribution curve. The measurement is usually performed in a wet manner. At this time, water and isopropyl alcohol containing a surfactant can be cited as the dispersion medium (the appropriate dispersion medium is selected in consideration of the surface treatment agent state of the conductive particles, etc.). As an example of a measuring device, the SALD series (SALD-2300, etc.) of Shimadzu Corporation can be cited. When the SALD series is used as a device, it is preferred to use an attached ultrasonic unit to generate ultrasonic waves while circulating the dispersion medium to measure the particle size.

[0128] Chemical composition of conductive particles

[0129] From the viewpoint of easy availability and good conductivity, the conductive particles preferably contain at least one element selected from the group consisting of silver and copper.

[0130] Specifically, the conductive particles preferably include at least one selected from particles containing silver as the main component and particles containing copper as the main component. Here, the expression "containing silver as the main component" means that the ratio of the silver element in all the constituent elements in the particles is preferably 50 mol% or more, more preferably 75 mol% or more, further preferably 90 mol% or more, and particularly preferably 95 mol% or more. Similarly, the expression "containing copper as the main component" means that the ratio of the copper element in all the constituent elements in the particles is preferably 50 mol% or more, more preferably 75 mol% or more, further preferably 90 mol% or more, and particularly preferably 95 mol% or more.

[0131] To be cautious, the conductive particles may contain elements other than silver and copper as long as the desired conductivity is obtained. Examples of elements other than silver and copper include gold, aluminum, platinum, palladium, iridium, tungsten, nickel, tantalum, lead, and zinc.

[0132] The conductive particles may contain two or more elements. For example, in the present embodiment, conductive particles (silver-coated copper particles) with silver plated on the surface of copper particles are preferably used. Silver-coated copper particles are particles with copper as the main component, for example, the surface of the copper particles is plated with silver in an amount of up to 35% by mass based on the total mass of the particles.

[0133] ·Method for obtaining conductive particles

[0134] The conductive particles that can be used in the present embodiment can be purchased from, for example, DOWA Electronics Co., Ltd., Fukuda Metal Foil Powder Co., Ltd., and the like.

[0135] Incidentally, in order to adjust and optimize the values ​​of (a), (b), (c), etc., two or more different conductive particles may be used in combination.

[0136] ·Ratio of conductive particles in the conductive composition

[0137] From the viewpoint of further reducing the resistivity of the conductive film, it is preferred that the ratio of conductive particles in the conductive composition is large. Specifically, the ratio of conductive particles in the total non-volatile components of the conductive composition is preferably 95% by mass or more, more preferably 97% by mass or more, further preferably 98% by mass or more, and particularly preferably 99% by mass or more.

[0138] In addition to the conductive particles, the conductive composition may contain

[0139] The conductive composition used in the coating step contains at least conductive particles satisfying the above-mentioned specific particle size distribution, but may contain components other than such conductive particles.

[0140] The conductive composition may contain a solvent. When the conductive composition contains a solvent, the coating property of the conductive composition on the substrate is improved. The solvent typically contains an organic solvent.

[0141] The type of solvent is not particularly limited, and any solvent may be used as long as it does not substantially alter the properties of the components in the conductive composition.

[0142] The amount of the solvent used can be appropriately adjusted according to the coating method of the conductive composition, etc. The amount of the solvent used is, for example, 3 to 30 mass %, preferably 5 to 25 mass %, and more preferably 10 to 20 mass % of the entire conductive composition.

[0143] From the viewpoint of adhesion to the substrate 1 , coating properties, printability, and the like, the conductive composition may or may not contain a binder.

[0144] When a binder is used, the type of the binder is not particularly limited, and preferred examples include polyvinyl pyrrolidone, polyester, epoxy resin, (meth)acrylic resin, polyvinyl acetal, cellulose resin (eg, ethyl cellulose), and phenolic resin.

[0145] From the viewpoint of particularly improving the conductivity of the conductive film, the amount of the adhesive in the total non-volatile components of the conductive composition is preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, and particularly preferably 1% by mass or less. The lower limit of the amount of the adhesive can be 0. However, in the case where it is desired to actively obtain effects such as improved adhesion by using an adhesive, the amount of the adhesive is preferably 1% by mass or more, more preferably 2% by mass or more, in the total non-volatile components of the conductive composition. That is, from the viewpoint of the balance of various properties, the amount of the adhesive is preferably 1 to 5% by mass, more preferably 2 to 5% by mass in the total non-volatile components of the conductive composition.

[0146] In addition, the conductive composition may or may not contain various additive components in conventional ink compositions and conductive pastes.

[0147] ·Substrate 1

[0148] The substrate 1 is generally in the form of a film, a sheet or a plate. From the viewpoint of industrial productivity, the shape of the substrate 1 is preferably any of these.

[0149] The substrate 1 is preferably flexible. By using the flexible substrate 1, a flexible printed circuit board (FPC) can be manufactured.

[0150] In addition, the flexible substrate 1 also has an advantage that a conductive film can be easily formed by a roll pressing step in the conductive film forming step described later.

[0151] To be cautious, the substrate 1 may be a rigid substrate without flexibility.

[0152] Considering the cost and the final use, the substrate 1 is preferably at least one selected from polyesters such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), polyolefins such as polyethylene and polypropylene, polyimide, and paper. Here, the paper may be coated paper (paper with a coating agent coated on the surface of the paper) or ordinary paper such as uncoated paper. In addition, as the substrate 1, it is not limited to PET and the like, and a general resin film can be used.

[0153] As described later, in the present embodiment, in the conductive film forming step, even in the case of no heating or relatively low temperature heating, a conductive film with sufficiently low resistivity can be obtained. Therefore, a substrate 1 with low heat resistance such as polyester, polyolefin, paper, etc. can also be suitably used as a substrate. In addition, when a substrate 1 with high heat resistance such as polyimide is used, the resistivity can be further reduced by performing high temperature heating in the conductive film forming step.

[0154] Coating method

[0155] The method for applying the conductive composition is not particularly limited.

[0156] The conductive composition can be applied to the entire side of the substrate, or only to a portion of one side of the substrate. In the former case, a knife coater, an air knife coater, a scraper, a roller coater, a bar coater (rod coater), a curtain coater and other devices can be used for coating. In the latter case, various printing methods, such as screen printing, gravure printing, relief printing, lithography (offset printing), inkjet printing, etc. can be applied. By appropriately designing the "pattern" of coating, a substrate having a pattern structure such as a conductive film (circuit pattern) that can function as a circuit and a mesh pattern with electromagnetic wave shielding ability can be manufactured. In the case of only applying the conductive composition to a portion of one side of the substrate, the "pattern" of coating is preferably appropriately designed according to the purpose of the conductive film finally obtained.

[0157] In order to prevent the conductive composition from being applied to a position other than a desired position, for example, a process may be performed in which a film with holes bored therein is placed on the substrate 1, the conductive composition is applied thereto, and then the film is removed.

[0158] The following supplements the case where screen printing is used as the coating method.

[0159] The material of the screen when the screen printing method is used can be synthetic fibers such as polyester or metal fibers such as stainless steel. From the viewpoint of durability and compatibility with conductive particles, the material of the screen is preferably metal fibers such as stainless steel.

[0160] When the screen printing method is adopted, advantages can be obtained by using an appropriate screen. Advantages include suppression of bleeding during continuous coating by the screen printing method and reduction of the surface roughness of the coating layer 3.

[0161] As an example, the screen is preferably roughened. It is believed that the solvent component in the conductive composition is easily integrated into the screen, reducing the friction force when the conductive composition passes through the screen. Moreover, even in the case of continuous screen printing, it is expected that the coating amount will be stabilized, the unevenness of the pattern surface will be reduced, etc.

[0162] The roughening treatment is preferably performed on a wire mesh made of metal fibers such as stainless steel.

[0163] As another example, it is preferred to perform a liquid-repellent treatment on the screen. Specifically, it is preferred to use a screen having a fluorine-containing material (fluorine resin, etc.), a silicon-containing material (organic silicon material) or the like attached to the surface to reduce the surface free energy. By using such a screen, it is possible to suppress the seepage when forming a pattern. That is, it is easy to form a fine pattern. In addition, it is also possible to expect a reduction in the concavity and convexity of the pattern surface.

[0164] Materials for performing liquid repellent treatment for screen printing are commercially available from, for example, Murakami Co., Ltd., Sonocom Co., Ltd., and the like.

[0165] As far as the inventors know, the conductive composition containing conductive particles satisfying the above (a) and (b) in this embodiment has good compatibility with the screen subjected to the roughening treatment and / or lyophobic treatment as described above. Although the details are not clear, some properties such as the fluidity of the conductive composition containing conductive particles having a specific particle size distribution may match the screen subjected to the roughening treatment and / or lyophobic treatment.

[0166] From the viewpoint of obtaining sufficient conductivity when forming a conductive film and the viewpoint of ease of coating, the thickness of the coating layer 3 (dry thickness when the conductive composition contains a solvent) is preferably 5 to 100 μm, more preferably 10 to 50 μm.

[0167] In particular, when the conductive composition contains a solvent, it is preferred to perform a heat treatment for drying the solvent. The conditions for the heat treatment are not particularly limited as long as the solvent is sufficiently dried, but from the viewpoint of sufficient drying of the solvent and suppression of deterioration of the conductive particles caused by excessive heating, the temperature of the heat treatment is preferably 50 to 150° C., more preferably 80 to 120° C. The time of the heat treatment is preferably 1 to 60 minutes, more preferably 3 to 30 minutes.

[0168] Specifically, the heat treatment for drying the solvent can be performed by blowing hot air to the coating layer 3. Of course, the heat treatment can also be performed by other methods.

[0169] ( Figure 2 : Conductive film forming step)

[0170] In the conductive film forming step, at least the coating layer 3 is pressurized to form a conductive film. Figure 2 The case where roll pressing is used as the pressing method is schematically shown.

[0171] When roller pressing is used as the pressurizing method, in the conductive film forming step, the substrate 1 provided with the coating layer 3 is sandwiched between two opposing rollers 10A and 10B. The sandwiched substrate 1 is rotated by the rollers 10A and 10B ( Figure 2 The force indicated by the arrow in Figure 2 from the left direction to the right direction.

[0172] In the rolling process, it is preferred to apply a pressure of 10 MPa or more to the substrate 1 provided with the coating layer 3. The pressure is more preferably 10 to 5000 MPa, further preferably 20 to 300 MPa, and particularly preferably 30 to 250 MPa. By applying a pressure of 10 MPa or more, the resistivity of the resulting conductive film can be further reduced. In addition, by applying a pressure of 5000 MPa or less, damage to the substrate 1 and the coating layer 3 can be suppressed. By the way, if the strength of the substrate 1 is sufficient, the pressure can be increased to further reduce the resistivity of the conductive film.

[0173] In the conductive film forming step, the coating layer 3 is preferably pressurized while being heated.

[0174] When the coating layer 3 is heated, the heating temperature can be appropriately set according to the heat resistance of the substrate 1, the type of conductive particles used, etc. For example, when the substrate 1 is composed of a material with low heat resistance such as polyester, polyolefin, or paper, the heating temperature is preferably set to a temperature at which the substrate does not substantially soften, melt, or carbonize, for example, within a range of 50 to 200° C., more preferably 70 to 180° C., further preferably 70 to 150° C., and particularly preferably 80 to 125° C., taking into account the heat resistance temperature of the substrate used. However, when the heating time is short, heating at a higher temperature (for example, a maximum of about 400° C.) may be permitted.

[0175] On the other hand, when the substrate 1 is made of a highly heat-resistant material such as polyimide, the heating temperature may be 50 to 400° C. That is, when the coating layer 3 is heated, the temperature is preferably appropriately adjusted to 400° C. or less.

[0176] The heating time can also be appropriately set according to the heat resistance of the substrate 1, the type of conductive particles used, etc. The heating time is, for example, 0.01 to 1 second, preferably 0.04 to 0.6 seconds. By the way, the "heating time" refers to the time when the coating layer 3 is heated while being pressed in contact with the roller when roller pressing is used in the conductive film forming process. As an example, if the contact width of the two rollers rotating oppositely is set to 1 mm, and the speed at which the substrate passes between the two rollers is set to v, the heating time (equal to the time of being pressed) is 0.59 seconds when v = 0.1 m / min, 0.04 seconds when v = 1.5 m / min, 0.06 seconds when v = 1.0 m / min, and 0.012 seconds when v = 5.0 m / min.

[0177] When roller pressing is used in the conductive film forming step, in order to heat and pressurize the coating layer 3, at least the roller 10A on the side close to the coating layer 3 of the two rollers is preferably heated. As described above, the heating temperature of the roller 10A can be appropriately set to 400° C. or less according to the heat resistance of the substrate 1, the type of conductive particles used, etc. In addition, the heating time can be adjusted by changing the rotation speed (i.e., the conveying speed) of the roller 10A and the roller 10B. The conveying speed can be appropriately adjusted between 0.1 and 10 m / min, for example, considering ensuring sufficient heating and pressing time, mass productivity, etc.

[0178] In order to achieve uniform heating and shorten the heating time, not only the roller 10A but also the roller 10B may be heated.

[0179] On the other hand, if a conductive film having a sufficiently low resistivity can be obtained, the roller 10A and the roller 10B may not be heated.

[0180] That is, if a conductive film with a sufficiently low resistivity can be obtained, the coating layer 3 does not need to be heated in the conductive film forming step. Specifically, when the conductive film forming step includes a roll pressing step, the roller 10A and the roller 10B may not be heated. In particular, when particles containing silver as a main component are used as conductive particles, a conductive film with a sufficiently low resistivity can be easily obtained even by only pressing.

[0181] Figure 2 Although not shown in the figure, in the rolling process, for example, the roller 10A and the roller 10B may be rotated while the resin film is sandwiched between the coating layer 3 and the roller 10A. By sandwiching the resin film between the coating layer 3 and the roller 10A, it is possible to suppress the coating layer 3 from peeling off and adhering to the roller 10A. In addition, by sandwiching the resin film between the coating layer 3 and the roller 10A, the pressure applied to the coating layer 3 is appropriately dispersed, so it is easy to obtain a conductive film with more uniform and constant performance.

[0182] The material of the resin film sandwiched between the coating layer 3 and the roller 10A is not particularly limited, but a polyimide film or the like can be preferably used from the viewpoint of heat resistance and durability.

[0183] It should be noted that the above description describes the roll pressing process as a specific method of the conductive film forming process, but the conductive film forming process may be performed by a method other than the roll pressing process as long as sufficient pressure (and sometimes heat) is applied to the coating layer 3. However, in consideration of the ease of mass production, the conductive film forming process preferably includes the roll pressing process.

[0184] For the sake of caution, the following describes steps other than the roll pressing step that can be used in the conductive film forming step.

[0185] like Figure 3 As shown in FIG. 1 , the conductive film forming step may include the following steps: placing the substrate 1 provided with the coating layer 3 on the flat surface 20A of the stage 20 having a flat surface, and applying pressure to the coating layer 3 from above using the roller 12. It should be noted that the stage 20 having a flat surface may be a flat plate instead of a stage as long as appropriate pressure can be applied. In short, as long as the substrate 1 is placed on the flat surface and appropriate pressure can be applied using the roller 12, it will suffice.

[0186] like Figure 4 As shown, the conductive film forming step may include the following step: the substrate 1 provided with the coating layer 3 is sandwiched between the first flat surface 31A of the first pressing member 31 having the first flat surface 31A and the second flat surface 32A of the second pressing member 32 having the second flat surface 32A. As an apparatus preferably used in performing such a step, for example, a pressing apparatus "CYPF-400" manufactured by Shinto Industry Co., Ltd. can be cited.

[0187] <Method for manufacturing electronic device>

[0188] The conductive substrate obtained through the coating step and the conductive film forming step can be used to manufacture electronic devices. For example, a substrate having a conductive film (circuit pattern) that can function as a circuit can be manufactured by appropriately designing the "pattern" of coating in the coating step, and the substrate can be combined with other electronic components to manufacture electronic devices.

[0189] Here, several examples of “electronic devices” are described, but it is needless to say that electronic devices including the conductive substrate obtained by the method for producing a conductive substrate according to the present embodiment are not limited to these.

[0190] Sensor: For example, the conductive substrate obtained by the method for producing a conductive substrate of the present embodiment can be applied to conductive components and circuits in sensors such as pressure-sensitive sensors and life sensors.

[0191] Solar cell: For example, the conductive substrate obtained by the method for producing a conductive substrate of the present embodiment can be applied to current collecting wiring of a solar cell.

[0192] Membrane switch: A membrane switch is a thin sheet-shaped switch made by printing circuits and contacts on a membrane and laminating them. To form the circuits and contacts, the method for producing a conductive substrate of this embodiment can be applied.

[0193] Touch sensor / touch panel: For example, the method for manufacturing a conductive substrate of this embodiment can be applied to form lead wiring in a touch sensor / touch panel. In addition, the method for manufacturing a conductive substrate of this embodiment can also be applied to form a transparent electrode in a touch sensor / touch panel.

[0194] Flexible substrate: Conventionally, a metal film is first applied to the entire surface of a flexible film, and then a chemical is used to remove unnecessary portions of the metal film to form a circuit. It is conceivable to use the method for manufacturing a conductive substrate of this embodiment to form a circuit instead of such conventional methods.

[0195] In particular, in electronic devices in which a circuit is conventionally formed using a conductive paste, by forming the circuit using the method for manufacturing a conductive base material of the present embodiment, the resistivity of the circuit is reduced, and it can be expected that the performance of the electronic device will be improved.

[0196] As a particularly preferred electronic device, an RF tag can be cited. That is, in order to produce a conductive circuit such as an antenna part in an RF tag, it is preferable to use the method for producing a conductive substrate of this embodiment.

[0197] For the specific structure of the RF tag, for example, Japanese Patent Application Laid-Open No. 2003-332714, Japanese Patent Application Laid-Open No. 2020-46834, etc. can be referred to.

[0198] <Method for producing electromagnetic wave shielding film>

[0199] As an application different from electronic devices, an electromagnetic wave shielding film can be manufactured by the method for manufacturing a conductive substrate of this embodiment. Specifically, in the coating step, the pattern when the conductive composition is coated is made a pattern (such as a mesh pattern) unique to the electromagnetic wave shielding film, thereby manufacturing the electromagnetic wave shielding film.

[0200] <Method for producing planar heating element>

[0201] As another application, it is considered to manufacture a planar heating element by the manufacturing method of the conductive substrate of this embodiment. A planar heating element refers to a heating element that generates heat by providing electrical wiring on a substrate and passing current through the wiring. As a specific example of a planar heating element, for example, a planar heating element used for anti-fogging and cold protection such as the rear window of a car can be cited.

[0202] <Conductive composition>

[0203] The embodiments of the present invention have been described above with the focus on the "method" of the method for producing a conductive substrate and the method for producing an electronic device. In addition, the embodiments of the present invention can also be considered as a conductive composition.

[0204] That is, the following conductive compositions are preferably used to form a conductive film having a low resistivity.

[0205] "A conductive composition containing conductive particles, for use in coating on a substrate to form a coating layer and at least pressurizing the coating layer to form a conductive film,

[0206] The above-mentioned conductive particles satisfy the following conditions.

[0207] (condition)

[0208] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the conductive particles by a laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 , the following (a) and (b) are satisfied.

[0209] (a)D 50 0.6~50μm.

[0210] (b)(D 90 -D 50 ) / D 50 0.55 to 3.0."

[0211] The specific embodiment of the composition has been described in the section "Method for producing a conductive substrate", and therefore, a repeated description thereof will be omitted.

[0212] The embodiments of the present invention are described above, but these are examples of the present invention, and various configurations other than the above can be adopted. In addition, the present invention is not limited to the above embodiments, and modifications and improvements within the scope of achieving the purpose of the present invention are included in the present invention.

[0213] Example

[0214] Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, the present invention is not limited to the Examples.

[0215] In the following, the symbol "E" is sometimes used to represent exponential expressions. For example, 1.3.E-06 means 1.3×10 －6 .

[0216] <Examples and Comparative Examples>

[0217] (Preparation of Conductive Particles)

[0218] Conductive particles having a particle size distribution shown in Table 1 were prepared. In Table 1, D 50 , D 10 , D 90 and D 95 The unit is μm.

[0219] These conductive particles are available from DOWA Electronics Co., Ltd. or Fukuda Metal Foil Co., Ltd. For example, "Copper 4" in Table 1 is a conductive particle available as product number "EFC-09LML" manufactured by Fukuda Metal Foil Co., Ltd.

[0220] [Table 1]

[0221] Table 1

[0222] Conductive particles <![CDATA[D 50 ]]> <![CDATA[D 10 ]]> <![CDATA[D 90 ]]> <![CDATA[D 95 ]]> <![CDATA[(D 90 -D 50 ) / D 50 ]]> <![CDATA[(D 50 -D 10 ) / D 50 ]]> Bronze 1 10.3 4.6 20 25 0.94 0.55 Bronze 2 4.5 2.4 7.4 8 0.64 0.47 Bronze 3 6.6 3.2 14.1 18 1.14 0.52 Bronze 4 1.4 0.6 2.2 2.9 0.57 0.57 Silver 1 6.1 2.0 16.0 19.1 1.62 0.67 Silver 2 0.8 0.3 1.5 1.8 0.88 0.63 Comparison with copper 0.4 0.3 0.6 0.6 0.50 0.25

[0223] In Table 1, D 50 The values ​​relating to particle size distribution are based on information provided by the distributor.

[0224] (Preparation of Conductive Composition)

[0225] 77 parts by mass of the conductive particles (copper 1 to copper 4, silver 1, silver 2, and comparative copper) and 23 parts by mass of an organic solvent were stirred using a planetary mixer to obtain a uniform paste-like conductive composition.

[0226] (Coating Step and Conductive Film Forming Step)

[0227] The coating step and the conductive film forming step are performed according to the following steps to produce a conductive substrate provided with a conductive film.

[0228] (1) A coating film (solid film) of 15 mm × 5 mm in size is formed on a substrate using a conductive composition. Specifically, first, 3M's Scotch Tape is attached to the substrate and a "hollow portion" of 15 mm × 5 mm in size is provided. Then, the conductive composition is scraped on the hollow portion using a scraper, and the hollow portion is filled with the conductive composition. Then, the Scotch Tape is peeled off. The thickness of the coating film at this time is about 40 μm.

[0229] As the substrate, a polyimide film was used.

[0230] (2) The substrate provided with the coating film was placed in a hot air circulation type atmospheric oven and heated at 100° C. for 15 minutes to dry the solvent.

[0231] (3) Use a load-adjustable roller press (Tester Sangyo, Inc., with a general structure as shown in the figure). Figure 2 The coating film after the solvent is dried is rolled together with the substrate under the following conditions.

[0232] Temperature of roller 10A: heated to 200°C

[0233] Pressure: 121MPa

[0234] Conveying speed: 0.1m / min

[0235] Incidentally, the above-mentioned pressure is a value obtained by the following calculation.

[0236] Based on roller width: 165mm, contact width between rollers: 1mm, the area to which pressure is applied is 165mm 2 .

[0237] The pressure is 20 kN.

[0238] · Due to the 165mm 2 A force of 20 kN is applied to the area, so 20 kN ÷ 165 mm 2 Calculation shows that the pressure is 121MPa.

[0239] (Determination of resistivity)

[0240] The resistance value of the conductive film obtained above was measured by a four-terminal resistance measuring device, and the film thickness was measured by a film thickness meter. The resistivity was calculated from the measured resistance value and film thickness.

[0241] The results are shown in Table 2.

[0242] [Table 2]

[0243] Table 2

[0244]

[0245] It can be seen from Tables 1 and 2 that by using (a) D 50 0.6~50μm and (b)(D 90 -D 50 ) / D 50 The conductive composition containing conductive particles having a resistivity of 0.55 to 3.0 can produce a conductive substrate having a conductive film with a low resistivity. Such a conductive substrate can be produced by a relatively simple process of rolling while heating the substrate provided with the coating layer.

[0246] Incidentally, the reason why the comparative example has a poor result can be explained by the fact that the particle size of the comparative copper is too small, so the number of grain boundaries between the conductive particles per unit volume is larger than that of the example (the presence of the grain boundaries may cause an increase in resistance).

[0247] (Coating step and conductive film forming step: Changes in substrate and heating temperature)

[0248] The conductive substrate was manufactured in the same manner as described above (coating step and conductive film forming step) except that the substrate was changed from a polyimide film to a low heat-resistant PET film and the temperature of the roller 10A was changed to 100° C. instead of 200° C. As the conductive composition, a conductive composition in a uniform paste state was prepared by stirring 77 parts by mass of conductive particles and 23 parts by mass of an organic solvent using a planetary mixer as shown in the table below.

[0249] The resistivity of the obtained conductive substrate was calculated in the same manner as in the above (Measurement of Resistivity).

[0250] [Table 3]

[0251] Table 3

[0252]

[0253] As shown in Table 3, even at a relatively low temperature of 100°C during the rolling process, a resistivity value of 10 －5 ~10 －6 A conductive film of the order of about 100 Å.

[0254] In the comparative examples in Table 2, even when the heating temperature during roll pressing was 200°C, the resistivity value remained at 10 －4 Considering this, at a relatively low temperature of 100°C during rolling, the resistivity value of 10 －5 ~10 －6 The usefulness of the method for producing a conductive substrate of the present embodiment is demonstrated.

[0255] Incidentally, in the above evaluation, no deformation or deterioration due to heat was observed in the PET film of the substrate.

[0256] <Additional example>

[0257] (Use adhesive to improve adhesion)

[0258] An additional experiment was conducted to verify the effect of improving the adhesion to the base material of the conductive film by using an adhesive.

[0259] Specifically, first, each component shown in Table 4 described later (the unit of numerical values ​​is "parts by mass") was uniformly stirred using a planetary mixer to prepare a conductive composition. Polyvinyl pyrrolidone as a binder was polyvinyl pyrrolidone manufactured by Nippon Shokubai Co., Ltd.

[0260] Using the prepared conductive composition, a conductive film was formed in the same manner as in the above (coating step and conductive film forming step), and the resistivity was calculated in the same manner as in the above (measurement of resistivity).

[0261] In addition, a commercially available cellotape (registered trademark) manufactured by Michibon Co., Ltd. was attached to the conductive film, and then the cellotape was rapidly peeled off in a direction perpendicular to the substrate surface to evaluate whether the conductive film was peeled off. The case where the conductive film was not peeled off was rated as "good", and the case where the conductive film was peeled off was rated as "poor".

[0262] Table 4 shows the composition and evaluation results of the conductive composition.

[0263] [Table 4]

[0264] Table 4

[0265]

[0266] As shown in Table 4, by using a relatively small amount of the binder, a conductive film having a low resistivity can be obtained, and the adhesion of the conductive film to the substrate can be improved.

[0267] (In particular, the resistivity values ​​of Additional Example 3, which has a relatively large amount of binder, and Additional Examples 1 and 2, which have a relatively small amount of binder, were confirmed.)

[0268] (Example of Change of Pressurization Method)

[0269] Use Figure 3 The conductive film was formed in the same manner as in the embodiment except that the step (3) in the (coating step and conductive film forming step) of the above-mentioned <Examples and Comparative Examples> was performed using the device combining "flat surface and roller" shown. At this time, the temperature was room temperature and the pressure was the same as 121 MPa in the embodiment. In addition, the conductive composition "Silver 1" in Table 2 was used as the conductive composition.

[0270] In addition, use Figure 4 The conductive film was formed in the same manner as in the embodiment except that the step (3) in the (coating step and conductive film forming step) of the above-mentioned <Examples and Comparative Examples> was performed using the device having "a pair of pressing members having flat surfaces". At this time, the temperature was room temperature and the pressure was the same as 121 MPa in the embodiment. In addition, the conductive composition of "Silver 1" in Table 2 was used as the conductive composition.

[0271] In these two additional examples, we also obtained －5 A conductive film having a resistivity value of the order of Ω·cm.

[0272] (Example of changing the pressure)

[0273] A conductive film was formed in the same manner as in the Example using "Copper 2" in Table 2 above, except that the pressing pressure was changed from 121 MPa to 242 MPa. The resistivity of the obtained conductive film was 5.8×10 －6 .

[0274] In addition, a conductive film was formed in the same manner as in the Example using "Copper 1" in Table 3 above, except that the pressure of the press was changed from 121 MPa to 242 MPa. The resistivity of the obtained conductive film was 2.2×10 －5 .

[0275] As described above, even when the pressing force is changed, a conductive film with a low resistivity can be formed.

[0276] (Example of using screen printing in coating process)

[0277] In the above-mentioned examples, the conductive composition was scraped on the "hollow portion" on the substrate using a scraper to form a coating film.

[0278] In addition, an example in which a screen printing method is used in the coating step is also described.

[0279] First, various conditions for screen printing are described.

[0280] Screen printing machine

[0281] Micro Tech Labtop 38

[0282] · Silk screen 1

[0283] Mesh material: SUS (stainless steel), 325 mesh, wire diameter: 16μm, emulsion thickness: 28μm, bias: 22.5°

[0284] The screen 1 is subjected to roughening treatment and liquid-repelling treatment. The specific method of roughening treatment is as follows Figure 5 The "roughened" image ( Figure 5 ( ) is a diagram showing a portion of the screen being enlarged.) In addition, the liquid-repelling treatment is performed by coating the surface of the screen with a substance having a property of repelling an organic solvent, etc., depending on the supply source of the screen, so that the contact angle when a mixed solvent of toluene:butanol=9:1 is dropped is about 60°.

[0285] Silk Screen 2

[0286] The same as screen 1 except that roughening treatment and liquid repelling treatment were not performed.

[0287] Scraper

[0288] Polyurethane scraper, hardness 80°

[0289] Conductive composition

[0290] The conductive composition used contained copper 2 in Table 1 and had a viscosity adjusted to 70 Pa·s. The viscosity was measured using an E-type viscometer manufactured by Toki Kogyo Co., Ltd. under the conditions of a chuck 3°×R9.7, a rotation speed of 10 rpm, and 25°C.

[0291] ·Printing conditions

[0292] The printing pressure was 0.18 MPa, the back pressure was 0.12 MPa, the speed was 50 mm / sec, and the gap was 2.0 mm.

[0293] The conductive substrate with a conductive film was manufactured in the same manner as in the above (coating step and conductive film forming step), except that the coating step was performed by the screen printing method under the above conditions using the screen 1. That is, (1) of the above (coating step and conductive film forming step) was performed by the screen printing method using the screen 1, but (2) thereafter, the conductive substrate with a conductive film was manufactured in the same manner. This example is referred to as "screen printing example 1".

[0294] In addition, a conductive substrate having a conductive film was manufactured in the same manner as in the above (coating step and conductive film forming step), except that the coating step was performed by the screen printing method under the above conditions using the screen 2. That is, (1) of the above (coating step and conductive film forming step) was performed by the screen printing method using the screen 2, but (2) thereafter, a conductive substrate having a conductive film was manufactured in the same manner. This example is referred to as "screen printing example 2".

[0295] In both of Screen Printing Examples 1 and 2, the resistivity of the obtained conductive film was at a level similar to that of the Examples in Table 2.

[0296] In addition, in order to understand the difference in performance caused by the difference in screen used for screen printing, the following evaluation was also performed.

[0297] Evaluation of continuous printing performance

[0298] The screen printing was performed 10 times in succession, and the pattern obtained at the 10th time was observed under a microscope.

[0299] A little bleed-out was observed in Screen Printing Example 2. In contrast, no bleed-out was observed in Screen Printing Example 1. This is presumably because in Screen Printing Example 1, the conductive composition was suppressed from wetting and spreading to the back side (substrate side) of the screen used.

[0300] Evaluation of the surface roughness of the pattern

[0301] The surface roughness (Rz) of the pattern surface after screen printing and heating in a hot air circulating atmosphere oven at 100° C. for 15 minutes was measured using a confocal laser microscope.

[0302] In Screen Printing Example 1, Rz was less than 30 μm, but in Screen Printing Example 2, Rz was 30 μm or more.

[0303] The surface roughness of the pattern is usually not particularly problematic depending on the purpose of the conductive substrate, but when the pattern is used as an antenna, the surface roughness is preferably small due to the so-called skin effect. By using an appropriate screen, a coating layer with a smaller surface roughness can be formed, and a conductive film with a smaller surface roughness can be formed. It is believed that a conductive substrate having such a conductive film can be preferably used as an antenna.

[0304] This application claims the benefit of priority based on Japanese patent application No. 2022-148049, filed on September 16, 2022, the disclosure of which is incorporated herein in its entirety.

[0305] Explanation of symbols

[0306] 1. Substrate

[0307] 3 Coating layer

[0308] 10A Roller

[0309] 10B Roller

[0310] 12 Rollers

[0311] 20 Table with flat surface

[0312] 20A Flat surface

[0313] 31 first pressing member

[0314] 31A First flat surface

[0315] 32 second pressing member

[0316] 32A Second flat surface

Claims

1. A method for manufacturing a conductive substrate, comprising the following steps: a coating step of coating a conductive composition containing conductive particles on a substrate to form a coating layer; and a conductive film forming step of at least pressing the coating layer to form a conductive film; The conductive particles satisfy the following conditions: condition: In the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by a laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 When the following (a) and (b) are satisfied, (a)D 50 0.6~50μm, (b)(D 90 -D 50 ) / D 50 It is 0.55~3.

0.

2. The method for producing a conductive substrate according to claim 1, wherein: The substrate has flexibility.

3. The method for producing a conductive substrate according to claim 1 or 2, wherein: In the conductive film forming step, the coating layer is heated and pressurized.

4. The method for producing a conductive substrate according to claim 1 or 2, wherein: Further satisfying the following (c), (c)(D 50 -D 10 ) / D 50 It is 0.4~0.

8.

5. The method for producing a conductive substrate according to claim 1 or 2, wherein: In the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by a laser diffraction scattering method, the particle size at which the cumulative frequency is 95% is defined as D 95 When D 95 1.5~100μm.

6. The method for producing a conductive substrate according to claim 1 or 2, wherein: The amount of the binder in the total non-volatile components of the conductive composition is 5 mass % or less.

7. The method for producing a conductive substrate according to claim 1 or 2, wherein: The substrate is at least any one selected from polyester, polyolefin, polyimide and paper.

8. The method for producing a conductive substrate according to claim 1 or 2, wherein: The conductive film forming step includes a rolling step of conveying the substrate provided with the coating layer between two opposing rollers.

9. The method for producing a conductive substrate according to claim 8, wherein: In the rolling step, one of the two rolls with which the coating layer contacts is not heated or is heated to 400° C. or less.

10. The method for producing a conductive substrate according to claim 8, wherein: In the roll pressing step, a pressure of 10 MPa or more is applied to the substrate provided with the coating layer.

11. The method for producing a conductive substrate according to claim 1 or 2, wherein: The conductive film forming step includes placing the substrate provided with the coating layer on a flat plate or on the flat surface of a table having a flat surface, and at least pressurizing the coating layer from above using a roller.

12. The method for producing a conductive substrate according to claim 1 or 2, wherein: The conductive film forming step includes a step of sandwiching the substrate provided with the coating layer between the first flat surface of a first pressing member having a first flat surface and the second flat surface of a second pressing member having a second flat surface.

13. The method for producing a conductive substrate according to claim 1 or 2, wherein: The conductive film has a pattern structure. 14 . 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 .

15. The method for manufacturing an electronic device according to claim 14, wherein: The electronic device is an RF tag. 16 . 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 claim 1 or 2.

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

18. A conductive composition containing conductive particles, for use in coating a substrate to form a coating layer and at least pressurizing the coating layer to form a conductive film, The conductive particles satisfy the following conditions: condition: In the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by a laser diffraction scattering method, the particle size at which the cumulative frequency is 50% is defined as D 50 , the particle size with a cumulative frequency of 10% is set as D 10 , the particle size with a cumulative frequency of 90% is set as D 90 When the following (a) and (b) are satisfied, (a)D 50 0.6~50μm, (b)(D 90 -D 50 ) / D 50 It is 0.55~3.

0.

19. The conductive composition according to claim 18, wherein The conductive particles further satisfy the following (c), (c)(D 50 -D 10 ) / D 50 It is 0.4~0.

8.

20. The conductive composition according to claim 18 or 19, wherein In the volume-based cumulative particle size distribution curve obtained when the particle size of the conductive particles is measured by a laser diffraction scattering method, the particle size at which the cumulative frequency is 95% is defined as D 95 When D 95 1.5~100μm.

21. The conductive composition according to claim 18 or 19, wherein The amount of the binder in the total non-volatile components is 5% by mass or less.

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