Substrate provided with conductive pattern, electronic device, electromagnetic wave shielding film, and planar heat generator

Abstract

A substrate provided with a conductive pattern includes a substrate and a conductive pattern formed using a plurality of conductive particles and including a straight portion on at least one side of the substrate. In the substrate, the distance from a first end to a second end of the straight portion of the conductive pattern in a direction orthogonal to the direction in which the conductive pattern extends is L. At this time, the thickness of the conductive pattern is greatest in a central region from a first reference position 2L / 5 from the center of the cross section toward the first end to a second reference position 2L / 5 from the center toward the side opposite the first end. In addition, when the maximum thickness of the conductive pattern in the cross section is T, the thickness of the conductive pattern in the cross section in an end region from the first end to L / 10 is 0.6T or less.

Description

Technical Field

[0001] This invention relates to a substrate having conductive patterns, an electronic device, an electromagnetic wave shielding film, and a planar heating element. More specifically, it relates to a substrate having conductive patterns with specific cross-sectional shapes manufactured using conductive particles, an electronic device comprising the substrate, an electromagnetic wave shielding film comprising the substrate, and a planar heating element comprising the substrate. Background Technology

[0002] Research has been conducted on forming conductive patterns, such as circuit patterns, on substrates using conductive compositions containing conductive particles. Conductive compositions containing conductive particles are sometimes also referred to as conductive pastes, conductive inks, etc.

[0003] Prior art regarding conductive pattern forming techniques using conductive compositions containing conductive particles can be exemplified by the following patent documents 1 to 4.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-029031

[0007] Patent Document 2: Japanese Patent Application Publication No. 09-293952

[0008] Patent Document 3: Japanese Patent No. 4259154

[0009] Patent Document 4: Japanese Patent No. 6533382 Summary of the Invention

[0010] When using a conductive composition containing conductive particles to form a conductive pattern on a substrate, the peeling of the conductive pattern from the substrate can sometimes become a problem.

[0011] Especially when the substrate is flexible, the conductive pattern is easily peeled off when the substrate is bent. In printed electronics, which has been actively researched in recent years, conductive patterns are mostly formed on flexible substrates, so it is important to suppress the peeling off of conductive patterns formed on flexible substrates.

[0012] The present invention was made in view of the following circumstances. One of the objects of the present invention is to suppress the peeling of conductive patterns formed on a substrate using a conductive composition containing conductive particles from the substrate.

[0013] The inventors have completed the invention described below, which solves the above-mentioned problems.

[0014] 1. A substrate having a conductive pattern, comprising:

[0015] Substrate, and

[0016] A conductive pattern located on at least one side of the aforementioned substrate, formed using a plurality of conductive particles, and including straight sections;

[0017] In the cross-section of the straight portion of the conductive pattern described above, in a direction orthogonal to the direction in which the conductive pattern extends, if the distance from the first end to the second end is set to L,

[0018] Within the central region, specifically the area extending from the center of the aforementioned cross-section towards the first reference position at a distance of 2L / 5 from the first end to the second reference position extending from the center towards the opposite side of the first end at a distance of 2L / 5, the thickness of the conductive pattern is at its maximum.

[0019] When the maximum thickness of the conductive pattern in the cross section is set to T, the thickness of the region from the first end to the end L / 10 in the cross section is 0.6T or less.

[0020] 2. The substrate with conductive patterns according to 1, wherein,

[0021] Both the first end and the second end mentioned above are conical.

[0022] When the foremost end of the first end is connected to the foremost end of the second end to form a lead segment l1, part or all of the lead segment l1 exists within the cross section.

[0023] 3. The substrate with a conductive pattern as described in 2, wherein,

[0024] When a straight line l2 perpendicular to the line segment l1 is drawn from any point on the line segment l1, (i) the intersection point of the line segment l2 and the portion of the outer periphery of the cross section opposite to the base material is set as P1, and (ii) the distance from P1 to the line segment l1 is set as m1, the maximum value of m1 is 0.1T or more.

[0025] 4. The substrate with a conductive pattern according to 2. or 3, wherein,

[0026] When a straight line l2 perpendicular to line segment l1 is drawn from any point on line segment l1,

[0027] (i) Let P2 be the intersection point of the straight line l2 and the portion of the outer periphery of the cross section that contacts the substrate.

[0028] (ii) Let the distance from P2 to line segment l1 be m2.

[0029] At this point, the maximum value of m2 is above 0.1T.

[0030] 5. The substrate having a conductive pattern according to any one of 1. to 4, wherein,

[0031] Some or all of the aforementioned conductive patterns are embedded in the aforementioned substrate.

[0032] 6. The substrate having a conductive pattern according to any one of 1. to 5, wherein,

[0033] The T values ​​are 1–100 μm and the L values ​​are 20–2000 μm.

[0034] 7. The substrate having a conductive pattern according to any one of 1. to 6, wherein,

[0035] At least a portion of the substrate that is in contact with the conductive pattern is composed of a cured product of a curable resin material.

[0036] 8. The substrate having a conductive pattern according to any one of 1. to 7, wherein,

[0037] In the volume-based cumulative particle size distribution curves obtained by measuring the particle size of the aforementioned conductive particles using laser diffraction scattering, the particle size D with a cumulative frequency of 50% is... 50 The range is 0.5–100 μm.

[0038] 9. The substrate having a conductive pattern according to any one of 1. to 8, wherein,

[0039] Among the aforementioned conductive particles, the proportion of low-melting-point metals with a melting point below 400℃ is 0–5% by mass.

[0040] 10. The substrate having a conductive pattern according to any one of 1. to 9, wherein,

[0041] The aforementioned substrate is flexible.

[0042] 11. The substrate having a conductive pattern according to any one of 1. to 10, wherein,

[0043] The aforementioned substrate comprises at least one selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide, and paper.

[0044] 12. An electronic device comprising a substrate having a conductive pattern as described in any one of 1. to 11.

[0045] 13. The electronic device according to 12, which is an RF tag.

[0046] 14. An electromagnetic wave shielding film comprising a substrate having a conductive pattern as described in any one of 1. to 11.

[0047] 15. A planar heating element comprising a substrate having a conductive pattern as described in any one of 1. to 11.

[0048] The conductive pattern in the substrate of the present invention is difficult to peel off from the substrate. Attached Figure Description

[0049] Figure 1 This is a diagram used to illustrate the cross-section of a conductive pattern.

[0050] Figure 2 This diagram illustrates the peeling suppression effect caused by the cross-sectional shape of the conductive pattern.

[0051] Figure 3 This diagram illustrates the peeling suppression effect caused by the cross-sectional shape of the conductive pattern.

[0052] Figure 4 This is a diagram used to illustrate the cross-section of a conductive pattern.

[0053] Figure 5 This is a diagram used to illustrate the cross-section of a conductive pattern.

[0054] Figure 6 This is a diagram illustrating a method for manufacturing a substrate having a conductive pattern.

[0055] Figure 7 This is a diagram illustrating a method for manufacturing a substrate having a conductive pattern.

[0056] Figure 8 A diagram illustrating the planar shape of the conductive pattern fabricated in the embodiment.

[0057] Figure 9 This is a cross-sectional view of the conductive pattern portion of the substrate with conductive patterns in Example 1.

[0058] Figure 10 This is a cross-sectional view of the conductive pattern portion of the substrate with conductive patterns in Example 2.

[0059] Figure 11 This is a cross-sectional view of the conductive pattern portion of the substrate with conductive patterns in Example 3. Detailed Implementation

[0060] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0061] In all the accompanying drawings, the same symbols are used to denote the same constituent elements, and descriptions are omitted where appropriate.

[0062] To avoid redundancy, (i) when multiple identical constituent elements exist in the same figure, only one of them is labeled, and sometimes not all of them are labeled; or (ii) especially Figure 2Later, sometimes regarding Figure 1 The same constituent elements will not be re-labeled.

[0063] All accompanying drawings are for illustrative purposes only. The shapes, dimensions, etc., of the components in the drawings may not correspond to the actual objects.

[0064] In this specification, the expression "X~Y" in the description of numerical ranges means above X and below Y, unless otherwise specified. For example, "1~5 mass%" means "more than 1 mass% and less than 5 mass%".

[0065] In this specification, the term "(meth)acrylic acid" indicates that it includes both acrylic acid and methacrylic acid. The same applies to terms such as "(meth)acrylate".

[0066] In this specification, the term "electronic device" is used to refer to components, devices, and end products that utilize electronic engineering technology, including semiconductor chips, semiconductor elements, printed circuit boards, electrical circuit display devices, information communication terminals, light-emitting diodes, physical batteries, and chemical batteries.

[0067] <Substrate with conductive patterns>

[0068] The substrate with conductive patterns in this embodiment includes:

[0069] Substrate, and

[0070] A conductive pattern, consisting of straight sections, is formed using a plurality of conductive particles and located on at least one side of the aforementioned substrate.

[0071] Figure 1 The cross-section of the aforementioned straight portion of the conductive pattern, in a direction orthogonal to the direction in which the conductive pattern extends, is schematically shown. Figure 1 The thick lines in the middle depict the outer perimeter of the cross-section of the conductive pattern. That is, Figure 1 The thick lines and their inner sides are cross-sections of the conductive pattern.

[0072] In the cross-section of the conductive pattern, the distance (total length) from the first end to the second end is denoted as L.

[0073] Within the central region, specifically the area from the center of the conductive pattern's cross-section towards the first reference position at a distance of 2L / 5 from the first end to the second reference position at a distance of 2L / 5 from the center of the conductive pattern's cross-section towards the opposite side of the first end, the thickness of the conductive pattern is at its maximum. Figure 1 The document records the "maximum thickness T".

[0074] When the maximum thickness of the conductive pattern in the conductive pattern cross section is set to T, the thickness of the end region from the first end (at least one end) to L / 10 in the conductive pattern cross section is 0.6T or less, preferably 0.5T or less, and more preferably 0.4T or less.

[0075] exist Figure 1 In the first end region, the part closest to the center region is the thickest part of the first end region, and the thickness decreases as it moves further away from the center region (gradually tapering shape). At this time, if the thickness t1 of the part closest to the center region (the boundary between the end region and the center region) of the first end region is 0.6T or less, then the thickness of any part of the first end region is 0.6T or less.

[0076] Similar to the end region on the first end side, the thickness of the end region in the conductive pattern cross-section from the second end (the other end) to L / 10 is preferably 0.6T or less, more preferably 0.5T or less, and even more preferably 0.4T or less. Figure 1 In the second end region, the part closest to the center region is the thickest part of the second end region, and the thickness decreases as it moves further away from the center region (gradually tapering shape). At this time, if the thickness t2 of the part closest to the center region (the boundary between the end region and the center region) of the second end region is 0.6T or less, then the thickness of any part of the second end region is 0.6T or less.

[0077] While not a strict description, in this embodiment, the cross-section of the conductive pattern may have a shape that tapers from the center to the ends. The numerical specifications mentioned above can be considered a quantitative representation of this shape.

[0078] Because the conductive pattern has this cross-sectional shape, compared to a rectangular conductive pattern, the possibility of an object being "stuck" by the conductive pattern when it comes into contact with it is suppressed. Therefore, it can be considered that the peeling off of the conductive pattern is suppressed (see reference). Figure 2 ).

[0079] Furthermore, especially when the conductive pattern is formed on a flexible substrate, because the cross-section of the conductive pattern has the aforementioned shape, the conductive pattern easily follows the substrate even when the substrate is bent. Therefore, peeling can be considered suppressed (see reference). Figure 3 ).

[0080] Incidentally, if only the conformability of the conductive pattern to the substrate when the substrate is bent is considered, it might be possible to simply thin the conductive pattern as a whole. However, in that case, there is a risk that the conductive pattern may not have a sufficient cross-sectional area to carry a sufficient current. In this embodiment, since the thickness of the conductive pattern is greatest in the central region and the end regions are tapered, the conductive pattern is ensured to have sufficient conductivity while also suppressing its peeling.

[0081] The substrate with conductive patterns in this embodiment can be manufactured using appropriate materials and appropriate manufacturing methods and conditions. If the manufacturing methods and conditions are inappropriate, it may sometimes be impossible to form conductive patterns with the specific cross-sectional shape described above.

[0082] The appropriate materials, manufacturing methods, and conditions will be detailed later, but a brief description of the appropriate manufacturing methods and conditions is provided first. The substrate with conductive patterns in this embodiment is manufactured through a series of processes including the following steps:

[0083] A transfer process involves contacting a provisional pattern, formed by a conductive composition containing conductive particles, applied to the surface of an easily peelable substrate, with an adhesive layer applied to the surface of a substrate different from the easily peelable substrate, to obtain a transfer pattern from the provisional pattern to the adhesive layer surface; and

[0084] An extrusion process in which pressure is applied to a transfer pattern to obtain a conductive pattern.

[0085] Through this series of processes, a conductive pattern with moderately crushed ends can be obtained when observing the cross-section.

[0086] The following is a more detailed description of this embodiment.

[0087] (Cross-sectional shape)

[0088] In this embodiment, it is acceptable as long as the thickness of the end region from the first end to L / 10 is 0.6T or less, preferably 0.6T or less for both the first end and the end region from the second end to L / 10. Even if only one of the two ends is tapered, it is considered that a peel suppression effect can be obtained at least in that portion. If both ends are tapered, it is considered that a further peel suppression effect can be obtained.

[0089] In the cross-section of the conductive pattern, one or both of the first and second ends are preferably conical, and both are more preferably conical.

[0090] Furthermore, when connecting the foremost end of the first end to the foremost end of the second end to form a lead segment l1, a portion or all of the lead segment l1 preferably exists within the cross section, and more preferably all of the lead segment l1 exists within the cross section.

[0091] More specifically, such as Figure 4 As shown, when a straight line l2 perpendicular to line segment l1 is drawn from any point on line segment l1,

[0092] (i) Let P1 be the intersection point of straight line l2 and the portion of the outer periphery of the cross section opposite to the substrate.

[0093] (ii) Let the distance from P1 to line segment l1 be m1.

[0094] At this point, the maximum value of m1 is preferably above 0.1T.

[0095] The maximum value of m1 is usually below 0.9T.

[0096] Similarly, as Figure 4 As shown, when a straight line l2 perpendicular to line segment l1 is drawn from any point on line segment l1,

[0097] (i) Let P2 be the intersection point of line l2 and the portion of the outer periphery of the cross section that contacts the substrate.

[0098] (ii) Let the distance from P2 to line segment l1 be m2.

[0099] At this point, the maximum value of m2 is preferably above 0.1T.

[0100] The maximum value of m2 is usually below 0.9T.

[0101] While not a strict description, the above roughly refers to the "spindle-shaped" cross-sectional shape of the conductive pattern. Because the conductive pattern has this cross-sectional shape, refer to the above... Figure 2 The described "object getting stuck" is further suppressed, or refer to the above. Figure 3 The description of "substrate conformity" is further improved, which means that the stripping of conductive patterns can be considered to be further suppressed.

[0102] Incidentally, in Figure 4 In the cross-section of the conductive pattern, the portion where m1 reaches its maximum value is the same as the portion where m2 reaches its maximum value, but as... Figure 5 As shown, depending on the cross-sectional shape of the conductive pattern, the part where m1 reaches its maximum value is sometimes different from the part where m2 reaches its maximum value.

[0103] The distance L from the first end to the second end is not particularly limited, but when considering the conductive pattern in an actual electronic device, the value of L is preferably 20 to 2000 μm, more preferably 50 to 1000 μm, and even more preferably 50 to 500 μm.

[0104] The maximum thickness T of the conductive pattern is not particularly limited, but when considering the conductive pattern in actual electronic devices, the value of T is preferably 1 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm.

[0105] (Substrate)

[0106] The substrate is typically in the form of a film, sheet, or plate. From an industrial productivity perspective, the shape of the substrate is preferably any of these.

[0107] The substrate is preferably flexible. Flexible printed circuit boards (FPCs) can be manufactured using a flexible substrate. Using a flexible substrate is preferred, for example, from a mass production perspective. Incidentally, the flexibility of the substrate, given the method for manufacturing a substrate with conductive patterns in this embodiment described later, may be related to the cross-sectional shape of the patterns.

[0108] The thickness of the substrate is not particularly limited and can be appropriately set according to the end application (electronic devices, RF tags, electromagnetic wave shielding films, planar heating elements, etc.) and various other factors. The substrate thickness is typically 10–250 μm, preferably 30–100 μm. However, from the viewpoint of suppressing curling during or after the manufacture of the substrate with conductive patterns, a certain degree of thickness is preferable. Specifically, the substrate thickness is preferably 100–250 μm, more preferably 100–150 μm.

[0109] Incidentally, the substrate thickness here can be determined by measuring the thickness of the portion of the substrate where there is no conductive pattern.

[0110] Considering cost and end use, the substrate preferably comprises 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. Here, the paper can be coated paper (paper whose surface is coated with a coating agent) or uncoated ordinary paper. The substrate is not limited to PET; general resin films can be used. Furthermore, the substrate can be transparent or opaque. Examples of opaque resin films include foamed resin films such as foamed PET films or foamed resin sheets.

[0111] In this embodiment, a substrate containing low heat-resistant materials such as polyester, polyolefin, polycarbonate, and paper can preferably be used as the substrate. Of course, a substrate containing high heat-resistant materials such as polyimide can also be used.

[0112] The substrate can consist of one layer or two or more layers.

[0113] For example, at least a portion of the substrate in contact with the conductive pattern may be composed of a cured resin material. That is, the substrate may comprise two layers: a substrate layer and a cured resin layer formed on one side of the substrate layer. Furthermore, at least a portion of the conductive pattern preferably contacts the cured resin layer. With this configuration, the adhesion between the conductive pattern and the substrate is further improved, potentially further suppressing the peeling of the conductive pattern.

[0114] When the substrate consists of two layers, a substrate layer and a resin cured layer, the substrate layer can be a resin film or paper as described above.

[0115] Curable resin materials are typically thermosetting and / or photocurable resin materials. Curable resin materials can possess both thermosetting and photocurable properties, or they can possess only one of these properties.

[0116] As curable resin materials, various thermosetting or photocurable resin materials can be cited as examples. Specifically, examples include materials containing epoxy resins, materials containing polymeric (meth)acrylates, urethane materials, materials containing urethane (meth)acrylates, and silicone materials, etc., which are thermosetting or photocurable resin materials.

[0117] Commercially available products can be used as curing resin materials. For example, various thermosetting or photocurable resin materials known or commercially available as hard coating agents can be used. In addition, various thermosetting or photocurable resin materials known or commercially available as primers can also be used.

[0118] When the curable resin material is thermosetting, it is preferable to perform thermosetting at a heating temperature that does not damage the substrate layer. For example, when the substrate layer contains resin, it is preferable to select a curable resin material that allows the curing reaction to proceed sufficiently when heated at a temperature below the glass transition temperature of the resin.

[0119] (Embedding into the substrate)

[0120] Part or all of the conductive pattern is preferably embedded in the substrate. That is, as shown in the example... Figure 1As shown, when the side of the substrate with the conductive pattern is taken as the upper surface and the opposite side is taken as the lower surface, it is preferable that part or all of the conductive pattern is located on the lower surface side of the upper surface of the portion of the substrate without the conductive pattern, and more preferably that part (not all) of the conductive pattern is located on the lower surface side of the upper surface of the portion of the substrate without the conductive pattern.

[0121] The maximum value of m2 mentioned above can be used as an indicator to quantitatively represent the degree to which the conductive pattern is embedded in the substrate. Specifically, if the first and second ends of the conductive pattern cross-section are located on the upper surface of the substrate, then the maximum value of m2 can be said to numerically represent the degree to which the conductive pattern is embedded in the substrate.

[0122] (Conductive particles)

[0123] The conductive pattern contains multiple conductive particles. Preferably, at least a portion of the multiple conductive particles in the conductive pattern are interconnected by sintering.

[0124] Regarding conductive particles, from the perspective of ease of obtaining and good conductivity, it is preferable to contain at least one element selected from the group consisting of silver and copper.

[0125] Specifically, the conductive particles preferably comprise at least one selected from the group consisting of particles primarily composed of silver and particles primarily composed of copper. Here, "primarily composed of silver" means that the proportion of silver in the total constituent elements of 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, "primarily composed of copper" means that the proportion of copper in the total constituent elements of 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.

[0126] Conductive particles can contain elements other than silver and copper, or they can contain none, as long as the desired conductivity can be achieved. Examples of elements other than silver and copper include gold, aluminum, platinum, palladium, iridium, tungsten, nickel, tantalum, lead, tin, and zinc.

[0127] However, from a cost perspective, the conductive particles preferably do not contain elements other than silver and copper, or if they do, they are contained in small amounts. Through the implementation of the extrusion process, particularly in the method for manufacturing a substrate with conductive patterns described later, it is possible to produce conductive patterns with good conductivity even if the conductive particles do not contain elements other than silver and copper, or if they do contain them, they are contained in small amounts. For example, in Patent Document 2 mentioned above, the conductive paste contains at least one low-melting-point metal selected from tin, lead, and indium. However, in this embodiment, the conductive particles may not contain such a low-melting-point metal. Specifically, the proportion of low-melting-point metals with a melting point of 400°C or less among the plurality of conductive particles is preferably 0 to 5% by mass, more preferably 0 to 3% by mass, and even more preferably 0 to 1% by mass.

[0128] Conductive particles may contain two or more elements. For example, conductive particles with silver plating on the surface of copper particles (silver-coated copper particles) are preferably used in this embodiment. Silver-coated copper particles are particles with copper as the main component, and for example, silver is plated on the surface of copper particles in an amount of up to 35% by mass based on the total mass of the particles.

[0129] In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of conductive particles using laser diffraction scattering, the particle size D with a cumulative frequency of 50% is... 50 Preferably, it is 0.5–100 μm, more preferably 0.6–50 μm, even more preferably 0.7–30 μm, and particularly preferably 0.7–20 μm.

[0130] D 50 When the size is appropriately large, it can reduce the number of grain boundaries between conductive particles per unit volume. This is believed to contribute to a lower resistivity in the resulting conductive pattern.

[0131] D 50 However, when the size is large, the "gap" between conductive particles decreases, which is believed to help make the resistivity of the resulting conductive pattern lower.

[0132] Conductive particles can be purchased from companies such as DOWA Electronics and Fukuda Metal Foil Powder Industry Co., Ltd. Two or more different conductive particles can be used together to adjust and optimize the particle size distribution or for other purposes.

[0133] <Method for manufacturing a substrate with conductive patterns>

[0134] Although briefly described, the substrate with conductive patterns in this embodiment can be manufactured using appropriate materials and appropriate manufacturing methods and conditions. If the manufacturing methods and conditions are inappropriate, it may sometimes be impossible to form conductive patterns with the specific cross-sectional shape described above.

[0135] Hereinafter, a preferred manufacturing method for the substrate having conductive patterns used in this embodiment will be described.

[0136] A preferred manufacturing method for producing the substrate having conductive patterns according to this embodiment includes:

[0137] A transfer process involves contacting a provisional pattern, formed by a conductive composition containing conductive particles, applied to the surface of an easily peelable substrate, with an adhesive layer applied to the surface of a substrate different from the easily peelable substrate, to obtain a transfer pattern from the provisional pattern to the adhesive layer surface; and

[0138] An extrusion process in which pressure is applied to a transfer pattern to obtain a conductive pattern.

[0139] The following is for reference Figure 6 and Figure 7 To explain the manufacturing method in more detail.

[0140] (A provisional pattern is formed on the surface of an easily peelable substrate:) Figure 6 P1, Figure 6 P2)

[0141] First, a provisional pattern is formed on the surface of an easily peelable substrate using a conductive composition containing conductive particles.

[0142] Specifically, firstly, as Figure 6 As shown in P1, a pattern 3, typically a paste containing a solvent and containing conductive particles, is formed on the surface of an easily peelable substrate 5. Then, by evaporating the solvent in pattern 3, as... Figure 6 As shown in P2, a provisional pattern (pattern 3B) can be obtained on the easily peelable substrate 5.

[0143] There are no particular limitations on the method of forming pattern 3. Various coating and printing techniques can be applied. Pattern 3 can be applied to the entire surface of one side of the easily peelable substrate 5, or only to a portion of one side of the easily peelable substrate 5. In the former case, pattern 3 can be formed by coating with a doctor blade coater, air knife coater, doctor blade coater, roller coater, bar coater, curtain coater, etc. In the latter case, pattern 3 can be formed by various printing methods, such as screen printing, gravure printing, letterpress printing, offset printing, inkjet printing, transfer printing, etc. By appropriately designing the "pattern" during printing, 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 capability can be finally manufactured. When pattern 3 is only applied to a portion of one side of the easily peelable substrate 5, the printed "pattern" is preferably appropriately designed according to the intended use of the substrate with the conductive pattern obtained at the end.

[0144] In order to prevent the pattern 3 from being formed outside the desired location on the peelable substrate 5, for example, a perforated film can be placed on the peelable substrate 5, a conductive composition can be coated or printed on it, and then the film can be removed.

[0145] Regarding the easily peelable substrate 5, there are no particular limitations as long as it can be easily peeled off in the peeling process described later, that is, the provisional pattern (pattern 3B) can be easily separated.

[0146] As an easy-to-peel substrate 5, resin films can be specifically cited. More specifically, resin films coated with silicone resin or resin films compounded with silicone resin can be cited. The main material of these resin films is not particularly limited, but polyester materials are preferred, and polyethylene terephthalate is more preferred, considering strength and cost. In addition, various films commercially available under names such as "release film" or "peel-off film" can also be used as easy-to-peel substrate 5.

[0147] Alternatively, release paper can also be used as the easy-to-peel substrate 5. Release paper typically refers to a composite processed paper with a film-like resin laminated onto it to impart easy-to-peel properties. Release paper is sometimes also called peeling paper. Various commercially available release papers can also be used appropriately.

[0148] The easily peelable substrate 5 can be as follows: Figure 6 P1 or Figure 6 P2 can be in the form of a film or sheet, but it can also be in the form of a roll, for example. For example, a roll with a surface material of metal or resin, capable of forming a provisional pattern on its surface, and capable of easily separating the provisional pattern can be used as the peelable substrate 5. By using the roll-shaped peelable substrate 5, it is expected that the productivity of substrates with conductive patterns can be improved.

[0149] The easily peelable substrate 5 can be used once or repeatedly.

[0150] The surface of the easy-peel substrate 5 is generally flat. The surface of the easy-peel substrate 5 generally does not have recesses or protrusions. The easy-peel substrate 5 is generally not a gravure or relief plate.

[0151] When the easily peelable substrate 5 is in the form of a film or sheet, its thickness is not particularly limited, but considering the operability and transfer accuracy of the easily peelable substrate 5, it is preferably 10 to 250 μm, and more preferably 10 to 100 μm.

[0152] The heating conditions for obtaining a provisional pattern (pattern 3B) by evaporating the solvent in pattern 3 can be, for example, 50–150°C for 1–60 minutes. However, regarding the temperature, it is preferable to set a temperature that will not damage the easily peelable substrate 5. As an example, heating can be performed by blowing hot air onto pattern 3; another example is by placing the easily peelable substrate 5 and pattern 3 on a hot plate. As yet another example, heating can also be performed by light. Specifically, examples include heating using a far-infrared heating furnace (IR oven) or Adphos NIR (ultra-near-infrared), heating using a high-brightness LED, and laser heating.

[0153] The height of the provisional pattern (pattern 3B) is preferably 0.5 to 100 μm, more preferably 5 to 60 μm, and even more preferably 10 to 40 μm. A height of 0.5 μm or more allows for better conductivity of the final conductive pattern. On the other hand, a height of 100 μm or less allows for a thinner overall substrate having the final conductive pattern. This is preferable, for example, in terms of miniaturization and weight reduction of electronic devices.

[0154] The conductive particles in the provisional pattern (pattern 3B) are preferably not substantially sintered. Incidentally, in this embodiment, the conductive particles are typically sintered in the extrusion process described later.

[0155] Furthermore, the provisional pattern (pattern 3B) is preferably not substantially cured. Specifically, even if the conductive composition contains a curable resin or crosslinking agent, the curable resin or crosslinking agent in the provisional pattern (pattern 3B) is preferably not substantially reacted before the transfer process.

[0156] From the perspective of ease of pattern formation, the conductive composition used to form the provisional pattern (pattern 3B) is preferably in the form of a paste at room temperature.

[0157] From the viewpoint of further improving the conductivity of the final conductive pattern, the amount of resin component in the conductive composition is preferably 15 parts by mass or less, i.e., 0 to 15 parts by mass, more preferably 0 to 10 parts by mass, and even more preferably 0 to 5 parts by mass, relative to 100 parts by mass of conductive particles. Furthermore, the remaining components in the conductive composition are preferably conductive particles. The conductive composition may also be resin-free, provided there are no issues with pattern formation. From the viewpoint of improving conductivity, the conductive composition preferably contains substantially no curable components other than the conductive particles.

[0158] On the other hand, from the viewpoint of improving pattern-forming properties, i.e., the printability or coating properties of the conductive composition, the conductive composition may also contain resin components such as resins or adhesives. To fully obtain the effect of using resin components, the amount of resin component in the conductive composition is preferably 1 to 15 parts by mass relative to 100 parts by mass of conductive particles, more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass. Furthermore, the remaining components in the conductive composition are preferably conductive particles.

[0159] Resin components that may be included in the conductive composition include, specifically, polyvinylpyrrolidone, polyester, epoxy resin, (meth)acrylic resin, polyvinyl acetal, cellulose resin (e.g., ethyl cellulose), phenolic resin, etc.

[0160] Conductive compositions may contain solvents. The presence of solvents in conductive compositions improves their coatability or printability on substrates. Solvents typically include organic solvents. Water may also be present in the solvent, provided that the conductive particles are properly dispersed.

[0161] There are no particular restrictions on the type of solvent. The solvent is acceptable as long as it does not substantially alter the composition of the conductive material.

[0162] The amount of solvent used can be adjusted appropriately according to the coating and printing methods of the conductive composition. The amount of solvent used in the total conductive composition is, for example, 3 to 30% by mass, preferably 5 to 25% by mass, and more preferably 10 to 20% by mass.

[0163] The specific manner in which the conductive particles are contained in the conductive composition has been described previously. Therefore, it will not be repeated here.

[0164] From the viewpoint of further reducing the resistivity of the final conductive pattern, the ratio of conductive particles in the conductive composition is preferably relatively large. Specifically, the ratio of conductive particles in all 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. In other words, from the viewpoint of further reducing the resistivity of the obtained conductive pattern, the conductive composition is preferably substantially free of resin components such as resins or adhesives. Here, "substantially free of" resin components means completely free of resin components, or although resin components are present, the amount is so small that the desired effect of using resin components cannot be obtained (for example, 1% by mass or less, specifically 0.5% by mass or less in all non-volatile components of the conductive composition). The conductive composition may be free of resins or adhesives as long as the desired conductive pattern can be obtained.

[0165] The conductive composition may also contain or not contain various additives found in conventional ink compositions or conductive pastes.

[0166] (Forming an adhesive layer on the substrate:) Figure 6 A)

[0167] Figure 6 Figure A shows that an adhesive layer 2 is provided on the surface of a substrate 1 that is different from the easily peelable substrate 5.

[0168] The substrate 1 is typically in the form of a film, sheet, or plate. From an industrial productivity perspective, the shape of the substrate 1 is preferably any of these.

[0169] The substrate 1 is preferably flexible. By using a flexible substrate 1, a flexible printed circuit board (FPC) can be manufactured. Using a flexible substrate 1, pressure can be easily applied using a "roller" in the extrusion process described later. This is preferred in terms of mass production. Incidentally, the substrate 1 can also be a rigid substrate without flexibility.

[0170] The thickness of substrate 1 is not particularly limited and can be appropriately set according to the end use (electronic devices, RF tags, electromagnetic wave shielding films, planar heating elements, etc.) and various other conditions. The thickness of substrate 1 is typically 10–250 μm, preferably 30–100 μm. However, from the viewpoint of suppressing curling, substrate 1 preferably has a certain thickness. Specifically, the thickness of substrate 1 is preferably 100–250 μm, more preferably 100–150 μm.

[0171] The substrate 1 can be a single-layer structure or a multi-layer structure with two or more layers.

[0172] Considering cost and end use, substrate 1 is preferably selected from at least one of the following groups: polyesters such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate); polyolefins such as polyethylene and polypropylene; polycarbonate; polyimide; and paper. Here, the paper can be coated paper or uncoated ordinary paper. Furthermore, substrate 1 is not limited to PET; a general resin film can be used. Additionally, substrate 1 can be transparent or opaque. Examples of opaque resin films include foamed resin films such as foamed PET film or foamed resin sheets.

[0173] In this embodiment, even without heating or at a relatively low temperature during the extrusion process, a conductive pattern with sufficiently low resistivity can be obtained. Therefore, a substrate 1 comprising low heat-resistant materials such as polyester, polyolefin, polycarbonate, or paper can preferably be used as the substrate. Furthermore, when a high heat-resistant substrate 1 such as polyimide is used, the resistivity of the resulting conductive pattern can be further reduced by performing high-temperature heating during the extrusion process.

[0174] The adhesive layer 2 is preferably thermosetting or photocurable. More preferably, the adhesive layer 2 is formed of a thermosetting resin material or a photocurable resin material. When the substrate 1 is light-transmitting, by making the adhesive layer 2 photocurable, light can be irradiated from the substrate 1 side to cure the adhesive layer 2. When the substrate 1 is not light-transmitting, by making the adhesive layer 2 thermosetting, heat can be used to cure the adhesive layer 2.

[0175] It should be noted in advance that the adhesive layer 2 may have both thermosetting and photocurable properties, or it may have only one of the thermosetting or photocurable properties.

[0176] Various thermosetting or photocurable resin materials can be cited as materials constituting the adhesive layer 2. Specifically, thermosetting or photocurable resin materials such as epoxy resin, polymeric (meth)acrylate, urethane, urethane (meth)acrylate, and silicone can be cited.

[0177] The adhesive layer 2 can also be made of commercially available products. For example, various thermosetting or photocurable resin materials known or commercially available as hard coating agents can be used to form the adhesive layer 2. In addition, various thermosetting or photocurable resin materials known or commercially available as primers can also be used.

[0178] When the adhesive layer 2 is thermosetting, it is preferable to form the adhesive layer 2 in a manner that allows for thermosetting at a heating temperature that does not damage the substrate 1. For example, when the substrate 1 is made of resin, it is preferable to design the adhesive layer 2 such that the curing reaction can proceed sufficiently when heated at a temperature below the glass transition temperature of the resin.

[0179] exist Figure 6 In stage A, the adhesive layer 2 is preferably in an uncured or semi-cured state, and more preferably in an uncured state.

[0180] The thickness of the adhesive layer 2 is not particularly limited, but considering sufficient adhesion, it is preferably 1 to 30 μm, more preferably 5 to 15 μm. The thickness of the adhesive layer 2 is considered to be related to the cross-sectional shape of the conductive pattern and the degree to which the conductive pattern is embedded in the substrate. Therefore, it is preferable to adjust the thickness of the adhesive layer 2 appropriately.

[0181] The adhesive layer 2 can be a single layer or two or more layers. For example, when the substrate 1 is paper, considering the penetration into the fibrous paper, a two-layer adhesive layer 2 can be used. In this case, the first adhesive layer closest to the paper acts as a "pore filler".

[0182] (Transfer process:) Figure 7 B)

[0183] In the transfer process, such as Figure 6The provisional pattern (pattern 3B) shown on P2 comes into contact with the adhesive layer 2 disposed on the surface of the substrate 1. Thus, the provisional pattern (pattern 3B) is transferred to the surface of the adhesive layer 2, resulting in a transferred pattern (pattern 3B).

[0184] In the transfer process, pressure may or may not be applied to improve the adhesion between the provisional pattern (pattern 3B) and the adhesive layer 2. Pressure is optional, provided the provisional pattern (pattern 3B) can be properly separated from the easily peelable substrate 5 at an appropriate stage. When pressure is applied, care should be taken to avoid altering the shape of the provisional pattern (pattern 3B). From the viewpoint of improving adhesion, pressure is generally preferred. Incidentally, in the embodiments described later, pressure is applied from the easily peelable substrate 5 side using a roller after the provisional pattern has come into contact with the adhesive layer. Besides using a roller, a flatbed press can also be considered for pressure application.

[0185] When adhesive layer 2 is uncured or semi-cured, it is believed that a portion of adhesive layer 2 will penetrate into the gaps between conductive particles in the provisional pattern (pattern 3B) during this transfer process. This is considered to help further improve the adhesion of the final conductive pattern.

[0186] (Adhesive layer curing process:) Figure 7 C)

[0187] Between the transfer process and the extrusion process, it is preferable to perform an adhesive layer curing process to cure the adhesive layer 2. As a result, the adhesion between the provisional pattern (pattern 3B) and the cured adhesive layer 2B formed by the curing of the adhesive layer 2 tends to be further improved.

[0188] Regarding the curing of adhesive layer 2, when adhesive layer 2 is photocurable, it can be cured by light such as ultraviolet light. Alternatively, when adhesive layer 2 is thermosetting, it can be cured by heating. Figure 7 C illustrates a method of curing the adhesive layer 2 by irradiating it with ultraviolet light (UV) from the transparent substrate 1 side. The conditions of light irradiation or heating can be appropriately adjusted and optimized according to the material properties constituting the adhesive layer 2. However, care should be taken to prevent heat damage to the substrate 1 when curing the adhesive layer 2 by heating.

[0189] In the adhesive layer curing process, it is preferable to completely cure the adhesive layer 2, but it is also permissible to cure it to a certain extent without complete curing. In either case, as long as the adhesion between the provisional pattern (pattern 3B) and the cured adhesive layer 2B formed by curing the adhesive layer 2 is improved, it is acceptable.

[0190] (Stripping process:) Figure 7 D)

[0191] Prior to the extrusion process described later, it is preferable to perform a peeling process to peel the easily peelable substrate 5 from the pattern 3B.

[0192] It should be noted in advance that, Figure 7 In this context, the peeling process is described as occurring between the adhesive layer curing process (C) and the oxide film removal process (E). However, as long as the desired substrate with conductive patterns can be obtained in the end, the peeling process can also be performed between the transfer process (B) and the adhesive layer curing process (C).

[0193] As long as the easily peelable substrate 5 can be properly peeled from pattern 3B, there are no particular limitations on the specific method and conditions of peeling.

[0194] (Oxide film removal process:) Figure 7 E)

[0195] In this embodiment, after the transfer process and before or simultaneously with the extrusion process described later, it is preferable to perform an oxide film removal process that brings the component X, which is capable of removing the oxide film on the surface of the conductive particles, into contact with the transfer pattern (pattern 3B). By performing the oxide film removal process, the sintering of the conductive particles in the subsequent extrusion process is easier, and the conductivity of the final conductive pattern tends to be further improved.

[0196] Component X preferably penetrates into the interior of the transfer pattern (pattern 3B) through the gaps between the conductive particles constituting the transfer pattern (pattern 3B). This further enhances the conductivity of the final conductive pattern. Therefore, in the oxide film removal process, pressure can be applied to the transfer pattern (pattern 3B) in contact with component X to promote the penetration of component X into the interior of the transfer pattern (pattern 3B). In this case, the oxide film removal process and the extrusion process described later are sometimes performed simultaneously.

[0197] Of course, the oxide film removal process can also be performed as a different process from the extrusion process.

[0198] Oxide film removal process, for example Figure 7 As shown in E, the transfer pattern (pattern 3B) can be transferred by contacting a liquid 7 containing a component X capable of removing the oxide film on the surface of conductive particles with the liquid 7, and preferably by allowing it to penetrate the liquid 7. Figure 2 E shows a method of dripping or spraying liquid 7 containing component X onto the transfer pattern (pattern 3B), but the transfer pattern (pattern 3B) can also be immersed in liquid containing component X. Alternatively, liquid 7 containing component X can be brought into contact with the embedded pattern (pattern 3B) by inkjet printing or a dispenser.

[0199] As a liquid containing component X, water in which component X is dissolved or dispersed is preferred. Using water is preferred in terms of reducing environmental impact and process safety (non-flammability). Of course, organic solvents in which component X is dissolved or dispersed can also be used.

[0200] Instead of using a liquid containing component X, the gaseous component X can also be brought into contact with the transfer pattern (pattern 3B) to perform the oxide film removal process.

[0201] Alternatively, it is also possible to bring the sheet containing component X into contact with the pattern 3B, preferably by applying pressure to allow component X to penetrate into the pattern 3B. Specific examples of the sheet include paper or nonwoven fabric containing component X, or resin sheets coated or printed with component X.

[0202] Furthermore, there are no particular limitations on the method by which component X comes into contact with and penetrates the transfer pattern (pattern 3B).

[0203] There are no particular limitations on component X as long as it can remove the oxide film on the surface of conductive particles.

[0204] In this specification, “removal” of oxide film includes not only the removal of the oxide itself present on the surface of conductive particles, but also the removal of oxides from their original state through chemical changes such as reduction.

[0205] According to the inventors' knowledge, it is preferable to contain at least one selected from the group consisting of organic acids, oxyacids of phosphorus, and hydrazine or its derivatives. These are particularly suitable when the conductive particles contain copper or silver.

[0206] Examples of organic acids include citric acid, formic acid, acetic acid, malonic acid, malic acid, tartaric acid, ascorbic acid, succinic acid, fumaric acid, and propionic acid.

[0207] Examples of oxyacids containing phosphorus include hypophosphonic acid, phosphonic acid, phosphorous acid, phosphoric acid, diphosphonic acid, triphosphonic acid, and metatriphosphonic acid. Hypophosphonic acid is particularly preferred.

[0208] Examples of hydrazine or its derivatives include hydrazine itself; hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine hydrobromide, hydrazine sulfate, and other hydrazine salts; in addition, compounds having the -NH-NH2 structure; etc.

[0209] Furthermore, from the perspective of removing oxide films, compounds with low pKa values ​​in water can be used as component X. Specifically, compounds with pKa values ​​of -5.0 to 5.0 in water are preferred as component X, and compounds with pKa values ​​of -4.0 to 4.5 are more preferred as component X. Incidentally, when component X is a polybasic acid, it is preferable that the smallest pKa among the plurality of pKa values ​​is within the above-mentioned range.

[0210] Considering only the small pKa and the resulting oxide film removal properties, inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid could also be used as component X. However, considering the potential problems that might arise if it remains in pattern 3B, component X is preferably an organic acid.

[0211] Additionally, the pKa value here can be a value at room temperature (e.g., 25°C). However, from the viewpoint of oxide film removal in actual processes, it is preferable to use the pKa value at the temperature of the permeation process or the conductive film formation process.

[0212] Furthermore, compounds that can restore oxide films to a non-oxidized state through reduction reactions can also be used as component X. For example, compounds with aldehyde groups can sometimes reduce oxides and therefore can be used as component X.

[0213] Furthermore, compounds with a low pKa in water and capable of restoring the oxide film to a non-oxidized state through reduction reactions are also preferred as component X. Formic acid is an example of such a compound. Formic acid has the advantage of being easily volatile and therefore unlikely to remain in the pattern.

[0214] In addition to the above, other components X include pyrogallol, phenanthrene, hydroquinone, and o-aminophenol. These are substances known in silver halide photography to function as reducing agents.

[0215] When a certain compound A is infiltrated into pattern 3B, resulting in a conductive pattern with lower resistivity compared to the case where it is not infiltrated, then compound A can be used as component X.

[0216] When a liquid that dissolves or disperses component X comes into contact with pattern 3B, the concentration of component X in the liquid can be appropriately adjusted. The concentration can be adjusted from the perspective of allowing a sufficient amount of component X to penetrate into pattern 3B and from the perspective of reducing the amount of residual component X to inhibit corrosion or deterioration of the conductive pattern.

[0217] The concentration of component X in the liquid is, for example, 0.05–50 mol / L, preferably 0.1–40 mol / L, more preferably 0.1–30 mol / L, even more preferably 0.1–10 mol / L, and particularly preferably 0.15–5.0 mol / L. Of course, liquids containing component X with concentrations lower than those shown herein, or liquids containing component X with concentrations higher than those shown herein (e.g., saturation concentration), can also be used.

[0218] In the case of the oxide film removal process, it is preferable to apply pressure to the transfer pattern (pattern 3B) at least before, specifically after the stripping process and before the oxide film removal process. This makes it easier to maintain the shape of the transfer pattern (pattern 3B) during the oxide film removal process. In particular, when the liquid that dissolves or disperses component X in the oxide film removal process penetrates into the transfer pattern (pattern 3B), it is easier to prevent at least a portion of the transfer pattern (pattern 3B) from deforming or collapsing due to the liquid. Especially when using a conductive composition that is substantially free of resin components, the transfer pattern (pattern 3B) is prone to deformation and collapse, therefore, applying pressure as described herein is preferable. In other words, when using a conductive composition containing resin components, the transfer pattern (pattern 3B) is less prone to deformation and collapse compared to a conductive composition that is substantially free of resin components, and therefore, even without applying pressure, the shape of the transfer pattern (pattern 3B) is often adequately maintained.

[0219] When applying pressure to the transfer pattern (pattern 3B) before the oxide film removal process, the method can be, for example, according to the extrusion process described later. Figure 7 The process described in F) is as follows. However, the pressure should preferably be adjusted appropriately. From the viewpoint of maintaining the shape of the transfer pattern (pattern 3B), higher pressure is preferred. However, from the viewpoint of the permeability of component X, since an appropriate gap needs to exist between the conductive particles, the pressure should not be too high.

[0220] Specifically, the pressure exerted on the transferred pattern (pattern 3B) during the pressurization process before the oxide film removal step is set as P. first The pressure applied to the transferred pattern (pattern 3B) in the conductive film formation process described later will be set as P. second When, P is preferred first <P second More specifically, P first P is preferred second The pressure is preferably 0.9 times or less, more preferably 0.75 times or less, and even more preferably 0.6 times or less. That is, the pressure in the extrusion process is preferably sufficiently smaller than the pressure required in the extrusion process to compact or sinter the conductive particles together.

[0221] From various perspectives, the optimal choice also applies to P. first and P second Each value is optimized.

[0222] P first Preferably, it is 1–500 MPa, more preferably 10–200 MPa, and even more preferably 20–100 MPa. When P first When the pressure is 1 MPa or higher, it is easy to reliably and sufficiently maintain the shape of the transferred pattern (pattern 3B) in subsequent processes. Additionally, when P... firstWhen the pressure is below 500 MPa, the "gap" used for the penetration of component X is easily retained in the transfer pattern (pattern 3B).

[0223] Additionally, P second For example, the pressure is 1 MPa or more, preferably 10 MPa or more, more preferably 10 to 5000 MPa, even more preferably 20 to 1000 MPa, particularly preferably 30 to 300 MPa, and especially preferably 50 to 250 MPa. When P second When the pressure is relatively large, the resistivity of the final conductive pattern can be further reduced. Additionally, when the pressure is not too high, damage to the substrate 1 or the transferred pattern (pattern 3B) can be suppressed. Incidentally, if the strength of the substrate 1 is sufficient, the resistivity of the final conductive pattern can be further reduced by increasing the pressure.

[0224] (Extrusion process:) Figure 7 F)

[0225] In the extrusion process, pressure is applied to the transfer pattern (pattern 3B). This increases the conductivity of the transfer pattern (pattern 3B), resulting in a conductive pattern 3C. Preferably, the conductive particles in the transfer pattern (pattern 3B) are sintered through the extrusion process. Furthermore, the pressure causes the transfer pattern (pattern 3B) to deform, resulting in a conductive pattern 3C with a cross-section that tapers from the center to the ends.

[0226] Pressurization Figure 7 As shown in Figure F, preferably after covering the exposed surface of the transfer pattern (pattern 3B) with component 6, pressure is applied to at least the transfer pattern (pattern 3B). Alternatively, pressure can be applied, for example, by clamping the laminate of the substrate 1, the cured adhesive layer 2B, the transfer pattern (pattern 3B), and component 6 between two opposing rollers 10A and 10B. Component 6 is preferably a film.

[0227] Incidentally, in Figure 7 In F, Figure 7 As described in E, liquid 7 containing component X, capable of removing the oxide film on the surface of conductive particles, exists above the transfer pattern (pattern 3B). In this case, pressure is applied to allow component X to penetrate into the transfer pattern (pattern 3B) and remove the oxide film from the conductive particles, while sintering of the conductive particles also occurs. That is, Figure 7 E and Figure 7 F can also be interpreted as indicating that the oxide film removal process and the extrusion process are carried out simultaneously.

[0228] By using component 6 during pressurization, direct contact between roller 10A and the transfer pattern (pattern 3B) can be avoided. Therefore, unintended deformation or collapse of the transfer pattern (pattern 3B) can be suppressed, making it easier to obtain a conductive pattern 3C with a cross-section tapering from the center to the ends.

[0229] In addition, component 6 acts as a "buffer material", which makes it easier to apply pressure evenly to the transfer pattern (pattern 3B). This may also be related to the fact that the cross-section of the final conductive pattern 3C is tapered from the center to the end.

[0230] From one perspective, the material of component 6 can be the same as that of substrate 1. That is, component 6 is preferably made of polyester film such as PET film.

[0231] From another perspective, to suppress the peeling or damage of the transferred pattern (pattern 3B), component 6 preferably uses an easy-peeling film or release paper. Specific examples of easy-peeling films or release papers include... Figure 6 The easily peelable substrate mentioned in the text 5.

[0232] In the extrusion process, it is preferable to apply pressure to the transfer pattern (pattern 3B) while heating it. As a result, the conductivity of the conductive pattern 3C tends to be better.

[0233] Preferably, the transfer pattern (pattern 3B) is pressurized at a pressure of 50 to 300 MPa and heated at a temperature of 80 to 150°C.

[0234] like Figure 7 When performing the extrusion process using two opposing rollers 10A and 10B as shown in F, it is preferable to use rollers with built-in adjustable temperature heaters.

[0235] (Any other process)

[0236] The method for manufacturing a substrate with conductive patterns according to this embodiment may also include steps other than those described above.

[0237] As an example, when component 6 is used in the extrusion process, component 6 is removed after the extrusion process is completed.

[0238] As another example, a removal process can be performed after the extrusion process to remove component X remaining on or inside the obtained conductive pattern. Specifically, this can include immersing the obtained substrate with the conductive pattern in a liquid (water or organic solvent) capable of dissolving or dispersing component X, or rinsing off residual component X by applying a liquid (water or organic solvent) to the surface of the conductive pattern. Alternatively, a process can be considered where the obtained substrate with the conductive pattern is heated at a temperature that does not damage the substrate 1, causing the residual component X to vaporize and disperse.

[0239] <Electronic Devices>

[0240] Electronic devices can be manufactured using the substrate with conductive patterns described in this embodiment. By appropriately designing the conductive patterns, a substrate with conductive patterns (circuit patterns) capable of functioning as a circuit can be manufactured. Then, by combining this substrate with other electronic components, electronic devices can be manufactured.

[0241] Here are some examples of electronic devices. It should be noted in advance that electronic devices are certainly not limited to these.

[0242] • Sensors: For example, conductive components / circuits in sensors such as pressure sensors and vital signs sensors can be applied to the substrate with conductive patterns of this embodiment.

[0243] • Solar cells: For example, the conductive patterned substrate of this embodiment can be used for the current collection wiring of solar cells.

[0244] • Membrane switch: A membrane switch is a thin-film switch formed by printing circuits and contacts on a membrane and then stacking them. The substrate with conductive patterns of this embodiment can be used to form its circuits or contacts.

[0245] • Touch sensor / touch panel: For example, to form the lead wiring in the touch sensor / touch panel, the substrate with conductive patterns of this embodiment can be used. Additionally, to form the transparent electrodes in the touch sensor / touch panel, the manufacturing method of the substrate with conductive patterns of this embodiment can also be considered.

[0246] • Flexible substrate: Conventionally, a metal film is first coated onto the entire surface of a flexible film, and then unwanted portions of the metal film are removed using a chemical agent to form a circuit. As an alternative to this conventional method, the circuit can be formed using the manufacturing method of a substrate with conductive patterns as described in this embodiment.

[0247] In particular, in electronic devices that have conventionally used conductive paste to form circuits, by forming circuits using the manufacturing method of this embodiment, the resistivity of the circuit can be reduced, and the performance of the electronic device is expected to be improved.

[0248] RF tags are a particularly preferred electronic device. Specifically, the substrate with conductive patterns in this embodiment is preferably used to manufacture conductive circuits such as the antenna portion of the RF tag.

[0249] For details regarding the specific structure of RF tags, please refer to Japanese Patent Application Publication No. 2003-332714 and Japanese Patent Application Publication No. 2020-46834.

[0250] <Manufacturing Method of Electromagnetic Wave Shielding Film>

[0251] As an application distinct from electronic devices, an electromagnetic wave shielding film can be manufactured using the method for manufacturing a substrate with a conductive pattern as described in this embodiment. Specifically, in the lamination process, an electromagnetic wave shielding film can be manufactured by setting the pattern (mesh pattern, etc.) during the printing of the conductive composition to a pattern specific to electromagnetic wave shielding films.

[0252] <Manufacturing Method of Planar Heating Element>

[0253] As a further different application, a planar heating element can be manufactured using the method for manufacturing a substrate with conductive patterns as described in this embodiment. A planar heating element is an object in which electrical wiring is provided on a substrate, and heat is generated by energizing the wiring. Specific examples of planar heating elements include those used for fogging or cold protection, such as those found in rear windows of passenger vehicles.

[0254] While embodiments of the present invention have been described above, these are merely examples, and various configurations other than those described may also be employed. Furthermore, the present invention is not limited to the above-described embodiments; modifications and alterations made within the scope of achieving the objectives of the present invention are also included in the present invention.

[0255] Example

[0256] Embodiments of the present invention will be described in detail based on examples and comparative examples. It should be noted in advance that the present invention is not limited to the examples.

[0257] <Preparation of Conductive Resin Composition>

[0258] • Manufacturing Example 1 (Resin-free)

[0259] Weigh D manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. 50 77.0 parts by mass of copper powder with a particle size of 5 μm and 23.0 parts by mass of organic solvent were mixed using a scraper to obtain a mixture. The mixture was then stirred using a rotary mixer.

[0260] The conductive composition of Manufacturing Example 1 was obtained as described above. The composition is a paste at 23°C.

[0261] <Example 1: Manufacturing of a substrate with conductive patterns>

[0262] A substrate with conductive patterns was manufactured through the following process.

[0263] (i) Forming a provisional pattern on the surface of an easily peelable substrate: equivalent to Figure 6 P1, Figure 6 P2

[0264] (ii) Forming an adhesive layer on the substrate: equivalent to Figure 6 A

[0265] (iii) Transfer printing process: equivalent to Figure 7 B

[0266] (iv) Adhesive layer curing process: equivalent to Figure 7 C

[0267] (v) Pressurization before oxide film removal process: not shown

[0268] (vi) Stripping process: equivalent to Figure 7 D

[0269] (vii) Oxide film removal process and extrusion process: equivalent to Figure 7 E and Figure 7 F

[0270] The following details each process.

[0271] (i) Forming a provisional pattern on the surface of an easily peelable substrate: equivalent to Figure 6 P1, Figure 6 P2

[0272] A provisional pattern was formed by screen printing the conductive composition of Manufacturing Example 1 (resin-free) onto an easy-to-peel substrate. Specific conditions are as follows.

[0273] • Easy-to-peel substrate: PET film with silicone resin coating manufactured by Fujimori Kogyo Co., Ltd.

[0274] • Printing press: Desk Top 38SA screen printing press (Micro-tec).

[0275] • Screen printing plate: using 325 mesh, 16μm wire diameter, and 28μm emulsion thickness.

[0276] • Printing conditions: printing pressure 0.18MPa, squeegee speed 30mm / second, gap (distance between screen and substrate) 2.0mm, attack angle 80°.

[0277] • Overall pattern shape: using, for example Figure 3 The antenna pattern shown is shown. The width of the thin lines in this pattern is 200 μm.

[0278] The screen-printed, easily peelable substrate is placed in a hot air circulating oven and heated at 100°C for 15 minutes. This causes the solvent to evaporate.

[0279] As described above, a provisional pattern with a height of 50 μm was formed on the surface of the easily peelable substrate.

[0280] (ii) Forming an adhesive layer on the substrate: equivalent to Figure 6 A

[0281] From the perspective of suppressing curling, the substrate is double-coated paper, namely mirror-coated platinum (180μm thick, manufactured by Oji Paper Co., Ltd.). Furthermore, considering penetration into the paper, the adhesive layer employs a two-layer structure. The specific steps for forming the adhesive layer are as follows.

[0282] First, a mixture of epoxy resin YX7200B35 (Mitsubishi Chemical Corporation) and solvent tetrahydrofuran was prepared at a mass ratio of 1:1. This mixture was then applied to the substrate surface using a bar coater to a wet thickness of 30 μm. Next, the substrate was placed in a hot air circulating oven and heated at 100°C for 15 minutes. This caused the solvent to evaporate, forming the first adhesive layer.

[0283] Next, a UV hard coating agent HX-RSC (Kyoei Chemical Co., Ltd., urethane acrylate material) was applied to the first adhesive layer using a bar coater. The substrate was then placed in a hot air circulating oven and heated at 80°C for 5 minutes. This caused the solvent to evaporate, forming the second adhesive layer. At this point, the coating amount and conditions of the UV hard coating agent HX-RSC were adjusted to achieve a dry thickness of 4 μm for the second adhesive layer.

[0284] The substrate with an adhesive layer is shown above.

[0285] (iii) Transfer printing process: equivalent to Figure 7 B

[0286] The substrate with the adhesive layer obtained in (ii) above is overlapped onto the provisional pattern obtained in (i) above, so that the provisional pattern comes into contact with the adhesive layer. Then, pressure is applied using a 2 kg roller. As a result, the provisional pattern is transferred to the adhesive layer side as a transfer pattern.

[0287] (iv) Adhesive layer curing process: equivalent to Figure 7 C

[0288] After step (iii) above, the adhesive layer with the transfer pattern was irradiated from the easy-to-peel substrate side using a UV-LED irradiation machine (Matsuo Sangyo Co., Ltd.) that emits ultraviolet light at a wavelength of 365nm, with a cumulative UVA intensity of 6000mJ / cm. 2 The ultraviolet light causes the adhesive layer to cure, thus forming a cured adhesive layer.

[0289] (v) Pressurization before oxide film removal process: not shown

[0290] The laminate containing the substrate, cured adhesive layer, transfer pattern and easy-to-peel substrate after the above (iv) is rolled using a load-adjustable roller press SA-602 (Tester Industrial Co., Ltd.) with two opposing rollers under the following conditions.

[0291] Roller temperature: 110℃, pressure: 20MPa, conveying speed: 0.1m / min, gap: 90-100μm

[0292] (Note 1: Regarding the roller temperature, the roller press is equipped with a non-contact temperature sensor, but a contact thermometer was used for measurement to obtain more accurate results.)

[0293] (Note 2: The pressure was obtained through the following calculations.)

[0294] Based on a roller width of 165mm and an inter-roller contact width of 3mm, the area for applying pressure is set to 495mm². 2 The pressure was set to 10 kN. Then, due to the pressure at 495 mm... 2 A force of 10kN was applied to the area, through 10kN ÷ 495mm 2 The calculation yielded a pressure of 20 MPa.

[0295] (vi) Stripping process: equivalent to Figure 7 D

[0296] After (v) above was completed, the easily peelable substrate was peeled off by hand.

[0297] (vii) Oxide film removal process and extrusion process: equivalent to Figure 7 E and Figure 7 F

[0298] For the pattern (transfer pattern) described above (vi), an oxide film removal solution (formic acid aqueous solution) is sprayed using a sprayer. The spraying amount is approximately 20 μL for an area of ​​about 30 mm × 20 mm on the substrate. Afterwards, a film-like component (a product manufactured by Fujimori Kogyo Co., Ltd., the same easily peelable substrate used when forming the provisional pattern) is laminated. In this state, a load-adjustable roller press SA-602 (Tester Sangyo Co., Ltd.) with two opposing rollers is used for roller pressing. The processing conditions are as follows.

[0299] Roller temperature: 110℃, pressure: 40MPa, conveying speed: 0.1m / min, gap: 40-50μm

[0300] (Note: The roller temperature and pressure are obtained in the same way as Notes 1 and 2 regarding the pressurization before the (v) oxide film removal process.)

[0301] As described above, pressure was applied to the pattern (transfer pattern) while the oxide film removal solution penetrated into the gaps between the conductive particles. A conductive pattern was then obtained.

[0302] Through the above series of processes, a substrate with conductive patterns is obtained, in which a conductive antenna pattern is formed on a paper substrate through a cured adhesive layer.

[0303] <Example 2: Manufacturing of a substrate with conductive patterns>

[0304] Except for adjusting the drying thickness of the second adhesive layer from 4 μm to 12 μm and adjusting the coating amount and coating conditions of the UV hard coating agent HX-RSC, a substrate with conductive patterns was obtained in the same manner as in Example 1.

[0305] <Example 3: Manufacturing of a substrate with conductive patterns>

[0306] Except for adjusting the drying thickness of the second adhesive layer from 4 μm to 6 μm and adjusting the coating amount and coating conditions of the UV hard coating agent HX-RSC, a substrate with conductive patterns was obtained in the same manner as in Example 1.

[0307] <Cross-section observation>

[0308] The obtained substrate with the conductive pattern is cut to expose a cross-section of the straight portion of the conductive pattern in a direction orthogonal to the extension direction of the conductive pattern. This cross-section is then photographed using an electron microscope. The cross-section of the substrate with the conductive pattern in Example 1 is shown below. Figure 9 A cross-section of the substrate with a conductive pattern in Example 2 is shown. Figure 10 A cross-section of the substrate with a conductive pattern in Example 3 is shown. Figure 11 .

[0309] Based on the captured electron microscope images, the corresponding values ​​were determined in the cross-sections of the conductive patterns in each embodiment. Figure 1 L, T, t1 and t2, Figure 4 or Figure 5 The lengths of m1 and m2. The values ​​are recorded in... Figures 9-11 This is also recorded in the table described later.

[0310] <Evaluation>

[0311] (Seamless fit)

[0312] The conductive patterned substrates of Examples 1-3 were bent by hand and the process of restoring them to their original flat shape was repeated 5 times. Afterwards, the presence or absence of conductive pattern peeling was confirmed by visual inspection and magnification. No peeling of the conductive pattern was observed, which was rated as good; peeling of the conductive pattern was observed, which was rated as poor.

[0313] (Electrical conductivity)

[0314] The results obtained in Examples 1-3 Figure 8 The pattern shown measures the resistance value R1 between points 1 and 2, and the resistance value R2 between points 3 and 4. Referring to the resistance values ​​of conventional RF tag antennas, conductivity is rated as "good" when at least one of R1 and R2 has a resistance value of 6Ω or less.

[0315] It should be noted in advance that the "6Ω" benchmark here is an example, and even exceeding this resistance value does not mean that the conductive pattern is immediately unusable in practice.

[0316] The various information is summarized in the table below.

[0317]

[0318] As shown in the table above, the conductive patterns of Examples 1 to 3, whose thickness at the end of the pattern is sufficiently smaller than that at the center of the pattern, are difficult to peel off when the substrate is bent.

[0319] In addition, the conductive patterns of Examples 1 to 3 have good conductivity.

[0320] This application claims priority based on Japanese Patent Application No. 2024-040886, filed on March 15, 2024, the entire disclosure of which is incorporated herein by reference.

[0321] Symbol Explanation

[0322] 1. Substrate

[0323] 2 Adhesive layer

[0324] 2B Cured Adhesive Layer

[0325] 3. Pattern

[0326] 3B Provisional Design

[0327] 3C conductive patterns

[0328] 5. Easy-to-peel substrate

[0329] 6 components (preferably membranes)

[0330] 7. A liquid containing component X capable of removing the oxide film on the surface of conductive particles.

[0331] 10A Roller

[0332] 10B roller

Claims

1. A substrate having a conductive pattern, comprising: Substrate, and A conductive pattern located on at least one side of the substrate, formed using a plurality of conductive particles, and including straight sections; When the distance from the first end to the second end is set to L in the cross section of the straight portion of the conductive pattern, in the direction orthogonal to the direction in which the conductive pattern extends, Within the central region, specifically the area extending from the center of the cross-section towards the first end at a distance of 2L / 5 (from the first reference position) to the second reference position extending from the center towards the opposite side of the first end at a distance of 2L / 5 (i.e., the central region), the thickness of the conductive pattern is at its maximum. When the maximum thickness of the conductive pattern in the cross section is set to T, the thickness of the end region from the first end to L / 10 in the cross section is less than 0.6T.

2. The substrate with a conductive pattern according to claim 1, wherein, Both the first end and the second end are tapered. When the foremost end of the first end is connected to the foremost end of the second end to form a lead segment l1, part or all of the lead segment l1 exists within the cross section.

3. The substrate having a conductive pattern according to claim 2, wherein, When a straight line l2 perpendicular to line segment l1 is drawn from any point on line segment l1, (i) the intersection point of l2 and the portion of the outer periphery of the cross section opposite to the substrate is set as P1, and (ii) the distance from P1 to line segment l1 is set as m1, the maximum value of m1 is 0.1T or more.

4. The substrate with a conductive pattern according to claim 2 or 3, wherein, When a straight line l2 perpendicular to line segment l1 is drawn from any point on line segment l1, (i) Let P2 be the intersection point of the straight line l2 and the portion of the outer periphery of the cross section that contacts the substrate. (ii) Let the distance from P2 to line segment l1 be m2. At this point, the maximum value of m2 is above 0.1T.

5. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, Part or all of the conductive pattern is embedded in the substrate.

6. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, The T ranges from 1 to 100 μm, and the L ranges from 20 to 2000 μm.

7. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, At least a portion of the substrate in contact with the conductive pattern is composed of a cured product of a curable resin material.

8. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, In the volume-based cumulative particle size distribution curve obtained by measuring the particle size of the aforementioned conductive particles using laser diffraction scattering, the particle size D with a cumulative frequency of 50% is... 50 The range is 0.5–100 μm.

9. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, Of the plurality of conductive particles, the proportion of low-melting-point metals with a melting point below 400°C is 0 to 5% by mass.

10. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, The substrate is flexible.

11. The substrate having a conductive pattern according to any one of claims 1 to 3, wherein, The substrate comprises at least one selected from the group consisting of polyester, polyolefin, polycarbonate, polyimide and paper.

12. An electronic device comprising a substrate having a conductive pattern as described in any one of claims 1 to 3.

13. The electronic device according to claim 12, wherein it is an RF tag.

14. An electromagnetic wave shielding film comprising a substrate having a conductive pattern as described in any one of claims 1 to 3.

15. A planar heating element comprising a substrate having a conductive pattern as described in any one of claims 1 to 3.

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