Patent Application
20250101594
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2023-159070 filed on Sep. 22, 2023. The above application is hereby expressly incorporated by reference, in its entirety, into the present application.
The present invention relates to a conductive substrate having a conductive thin wire and a manufacturing method for a conductive substrate.
A conductive substrate having a conductive thin wire (a thin wire-shaped wire that exhibits conductivity) is widely used in various use applications such as touch panels.
Regarding a conductive thin wire of a conductive substrate, a photosensitive layer containing a silver halide is subjected to an exposure treatment, a development treatment, and the like in sequence to form a conductive thin wire containing metallic silver, for example, as disclosed in JP2022-161790A.
JP2022-161790A discloses a manufacturing method for a conductive substrate, the manufacturing method including, in the following order, a step 1 of forming a thin wire containing metal on the substrate; a step 2 of bringing the thin wire into contact with a solution containing an organic acid; and a step 3 of subjecting the thin wire to a plating treatment to form a conductive thin wire.
In a case where a conductive substrate having a conductive thin wire is used for, for example, a touch panel, the conductive thin wire is required to have excellent conductivity, that is, to have a small electric resistance.
In addition, there has been a demand for further wire thinning of conductive thin wires; however, there is a problem that migration easily occurs in a conductive pattern formed of such conductive thin wires. In a case where migration occurs between conductive thin wires, there is a concern that the conductive thin wires become electrically conductive therebetween and do not carry out the circuit function. For this reason, there is a demand for a conductive substrate having improved migration suppressing performance.
As a result of examining a conductive substrate having a conductive thin wire with reference to JP2022-161790A, the inventors of the present invention found that there is room for further improvement in a conductive substrate having excellent conductivity and excellent migration suppressing performance.
In consideration of the above-described circumstances, an object of the present invention is to provide a conductive substrate having excellent conductivity and excellent migration suppressing performance, and a manufacturing method for the conductive substrate.
[1] A conductive substrate comprising:
[2] The conductive substrate according to [1], in which a line width of the conductive thin wire is 0.1 μm or more and less than 5.0 μm.
[3] The conductive substrate according to [1] or [2], in which in a vertical cross section of the conductive thin wire in a direction orthogonal to a direction in which the conductive thin wire extends, a ratio of a height of the conductive thin wire to a line width of the conductive thin wire is 0.6 or more and less than 1.5.
[4] The conductive substrate according to any one of [1] to [3], in which the silver contained in the conductive thin wire has a particle shape.
[5] The conductive substrate according to any one of [1] to [4], in which the substrate is a substrate having flexibility.
[6] The conductive substrate according to [5], in which a material constituting the substrate having flexibility is at least one selected from the group consisting of polyethylene terephthalate, a cycloolefin polymer, a cycloolefin copolymer, and polycarbonate.
[7] A manufacturing method for a conductive substrate, in which a conductive substrate including a substrate and a conductive thin wire that contains silver and is disposed on the substrate is manufactured, the manufacturing method for a conductive substrate comprising, in the following order:
[8] The manufacturing method for a conductive substrate according to [7], in which the electroless plating treatment is an electroless silver plating treatment.
According to the present invention, it is possible to provide a conductive substrate having excellent conductivity and excellent migration suppressing performance, and a manufacturing method for the conductive substrate.
Hereinafter, a conductive substrate according to the embodiment of the present invention will be described in detail with reference to the drawings.
The following configuration requirements will be described based on the representative embodiment of the present invention; however, the present invention is not limited to such an embodiment.
Each drawing is an exemplary drawing for describing the present invention, and the present invention is not limited by each drawing. In addition, the scale of constitutional elements shown in each drawing may be different from the actual scale.
In the present specification, the numerical value range indicated by using “to” means a range including the numerical values before and after “to” as the lower limit value and the upper limit value, respectively. Further, in the present specification, as each component, a substance corresponding to each component may be used alone, or two or more kinds of substances may be used in combination. Here, in a case where two or more kinds of substances are used in combination for each component, the content of the component refers to the total content of the substances used that is used in combination unless otherwise specified.
In the present specification, “g” and “mg” indicate “g in terms of mass” and “mg in terms of mass”, respectively.
In the present specification, the “polymer” or the “polymeric compound” means a compound having a weight-average molecular weight of 2,000 or more. Here, the weight-average molecular weight (Mw) is defined as a polystyrene equivalent value according to the gel permeation chromatography (GPC) measurement.
In addition, the term “orthogonal” or “perpendicular” in terms of an angle means a range of 90°±5°, and the term “parallel” means a range of 0°±5°. Similarly, an angle is meant such that a difference from the exact angle is within 5 degrees unless otherwise specified. The angle difference described above is preferably 4 degrees or less and more preferably 3 degrees or less.
A conductive substrate according to the present invention has a substrate and a conductive thin wire that contains silver and is disposed on the substrate.
The conductive substrate 10 has a substrate 12 and a conductive thin wire 14 disposed on the surface 12a of the substrate 12 and containing silver. Although two conductive thin wires 14 that extend in one direction are illustrated in
A vertical cross section Ac shown in
The substrate is not particularly limited as long as it is a member that is capable of supporting the conductive thin wire, and examples thereof include a plastic substrate, a glass substrate, and a metal substrate.
From the viewpoint of the excellent bendability of the obtained conductive member, the substrate is preferably a substrate having flexibility. Examples of the material constituting the substrate having flexibility include polyethylene terephthalate (PET), a cycloolefin polymer (COP), a cycloolefin copolymer (COC), and polycarbonate (PC). Among the above, PET is preferable since it has excellent adhesiveness to the conductive thin wire.
The thickness of the substrate is not particularly limited, and it is 25 to 500 μm in a large number of cases. In a case where the conductive substrate is applied to a touch panel, the thickness of the substrate may exceed 500 μm in a case where the surface of the substrate is used as a touch surface.
The total light transmittance of the substrate is preferably 85% to 100%. The total light transmittance is measured using “Plastics—Determination of total light transmittance and total light reflectivity” specified in Japanese Industrial Standards (JIS) K 7375: 2008.
An undercoat layer may be disposed on the surface of the substrate.
The undercoat layer preferably contains a specific polymer described later. In a case where this undercoat layer is used, the adhesiveness of the conductive thin wire described later to the substrate is further improved.
A method of forming the undercoat layer is not particularly limited, and examples thereof include a method of applying a composition for forming an undercoat layer, containing a specific polymer described later, onto a substrate and carrying out a heating treatment as necessary. Optionally, the composition for forming an undercoat layer may include a solvent. The kind of the solvent is not particularly limited, and examples thereof include a solvent that is used in a composition for forming a photosensitive layer, which will be described later. In addition, as the composition for forming an undercoat layer containing the specific polymer, latex that contains particles of the specific polymer may be used.
The thickness of the undercoat layer is not particularly limited, and it is preferably 0.02 to 0.3 μm and more preferably 0.03 to 0.2 μm from the viewpoint that the adhesiveness of the conductive layer to the substrate is more excellent.
A conductive thin wire including silver is disposed on a surface of the substrate. Since the conductive thin wire contains silver, the conduction characteristics of the conductive substrate are ensured.
The description that the conductive thin wire is disposed on the surface of the substrate means that the conductive thin wire may be in direct contact with the surface of the substrate or the substrate and the conductive thin wire may be disposed with another layer (for example, an undercoat layer) being interposed between.
In the present specification, the conductive thin wire is intended to be a thin wire-shaped region that is disposed on the surface of the substrate and integrally formed of a material containing silver. For example, a silver halide-free layer formed by a step E described later, and a protective layer formed by a step F described later constitute the conductive thin wire together with a thin wire-shaped silver-containing layer formed by a step A and a step B described later.
In addition, the conductive thin wire disposed on the surface of the substrate may be or may not be electrically connected to a member in the outside of the conductive substrate. A part of the conductive thin wire may be a dummy electrode electrically isolated from the outside.
The conductive thin wire contains silver (metallic silver). The silver contained in the conductive thin wire may be a simple substance of silver or may be a mixture of silver and another metal other than the silver. Examples of the other metal include copper (metallic copper), gold (metallic gold), nickel (metallic nickel), and palladium (metallic palladium), where copper is preferable.
Hereinafter, the term “silver” means “metallic silver” unless otherwise specified.
The conductive thin wire is preferable to be composed of a simple substance of silver or a mixture of silver and copper, or it is more preferable to be composed of a simple body from the viewpoint that the occurrence of disconnection trouble of the conductive thin wire can be suppressed.
The silver contained in the conductive thin wire usually has a particle shape. The average particle diameter of the silver which has a particle shape is preferably 10 to 1,000 nm and more preferably 10 to 200 nm in terms of a sphere equivalent diameter. Here, the sphere equivalent diameter is the diameter of spherical particles having the same volume, and the average particle diameter of the silver particles is obtained as an average value obtained by measuring the sphere equivalent diameters of one hundred objects and arithmetically averaging them.
The shape of the silver particle is not particularly limited, and examples thereof include a spherical shape, a cubic shape, a flat plate shape, an octahedron shape, and a tetradecahedron shape. In addition, in the conductive thin wire, silver may have a shape other than the particle shape. For example, silver may have a form in which silver is partially or entirely fused and bonded or may have a form in which silver is layered to be dispersed in the conductive thin wire.
The conductive thin wire may have a structure in which a plurality of silvers are dispersed in a polymeric compound, or silver particles may be aggregated in the polymeric compound to be present as an aggregate. In addition, at least a part of the plurality of silvers contained in the conductive thin wire may be bound to each other by a silver plating treatment described later. The polymeric compound will be described later.
The content of silver in the conductive thin wire is not particularly limited, and from the viewpoint that the conductivity of the conductive substrate is more excellent, the content of silver per area of the region in which the conductive layer thin wire on the surface of the substrate is disposed is preferably 0.01 to 10 g/m2 and more preferably 0.03 to 1 g/m2.
The content of silver in the conductive thin wire can be adjusted, for example, by the content of the silver component (for example, a silver halide contained in a composition for forming a photosensitive layer described later) contained in a composition for forming the conductive thin wire and the silver plating amount in the plating treatment described later.
In addition, the content of silver in the conductive thin wire is obtained by measuring the weight of silver contained in the conductive thin wire per area of the main surface of the substrate using a fluorescent X-ray measuring device.
In the conductive thin wire according to the embodiment of the present invention, a ratio of an amount of iodine atoms to an amount of silver atoms (hereinafter, also referred to as a “ratio I/Ag” in the present specification), which is detected in a case where a surface of the conductive thin wire is measured by a fluorescent X-ray analysis, is 0.035 to 0.100.
Since the ratio I/Ag on the surface of the conductive thin wire is 0.035 to 0.100, the conductive substrate according to the embodiment of the present invention has excellent conductivity and excellent migration suppressing performance. Although the reason why the conductive substrate according to the embodiment of the present invention exhibits the above-described excellent effects is not clear, it is presumed to be as follows. In a case where a certain amount or more of iodine is present on the surface of the conductive thin wire, the migration of the conductive thin wire is suppressed. On the other hand, in a case where the amount of iodine present on the surface of the conductive thin wire is too large, the conductivity of the conductive substrate is reduced, which is presumed to be because the proportion of silver in the conductive thin wire is reduced.
Hereinafter, the description that “the effect of the present invention is more excellent” means that at least one of the migration suppressing performance or the conductivity is excellent in the conductive substrate.
Hereinafter, a description will be made for a measuring method for the ratio I/Ag on the surface of the conductive thin wire according to the fluorescent X-ray analysis method.
The ratio I/Ag was measured by repeating Ar sputtering (2 kV, Ar ions, 2 mm×2 mm) that was carried out from a surface of the conductive thin wire on a side opposite to the substrate in the depth direction, and a fluorescent X-ray analysis (XPS, X-ray source: Al Kα, Quantera SXM manufactured by ULVAC-PHI, Inc.).
A sample of the conductive substrate is repeatedly subjected to the above-described Ar sputtering and a fluorescent X-ray analysis, and then a position at a depth where a ratio of the number of metal atoms is 15% or more with respect to the total number of atoms is defined as the surface of the conductive thin wire, and the side of the substrate from this position is defined as the inside of the conductive thin wire. Then, the surface of the conductive thin wire is subjected to a fluorescent X-ray analysis, and the ratio I/Ag (content of iodine atoms/content of silver atoms) can be determined from the measured values of the atomic amount of the silver atoms and the atomic amount of the iodine atoms.
It is noted that on the surface of the conductive thin wire, it is presumed that the iodine atom is present as an iodine-containing compound such as silver iodide or potassium iodide.
From the viewpoint that the effect of the present invention is more excellent, the ratio I/Ag on the surface of the conductive thin wire is preferably 0.040 to 0.080.
The ratio I/Ag on the surface of the conductive thin wire can be adjusted, for example, by amounts of an iodine compound and a reducing agent which are contained in a plating treatment liquid that is used for an electroless plating treatment in a step W of carrying out an electroless plating treatment in a manufacturing method for a conductive substrate which will be described later and then forming the conductive thin wire.
The conductive thin wire may contain a polymeric compound in addition to silver and iodine (iodine compound).
The kind of the polymeric compound contained in the conductive thin wire is not particularly limited, and a publicly known polymeric compound can be used. Among the above, it is preferably a polymeric compound different from gelatin (hereinafter, also referred to as “specific polymer”) from the viewpoint that it is possible to form a conductive thin wire having higher strength.
The kind of specific polymer is not particularly limited as long as it is different from gelatin, and the specific polymer is preferably a polymer that is not decomposed by a proteolytic enzyme or an oxidizing agent described later which decomposes gelatin.
Examples of the specific polymer include a hydrophobic polymer (a water-insoluble polymer), which includes, for example, at least any one resin selected from the group consisting of a (meth)acrylic resin, a styrene-based resin, a vinyl-based resin, a polyolefin-based resin, a polyester-based resin, a polyurethane-based resin, a polyamide-based resin, a polycarbonate-based resin, a polydiene-based resin, an epoxy-based resin, a silicone-based resin, a cellulose-based polymer, and a chitosan-based polymer, or a copolymer consisting of monomers that constitute these resins.
In addition, the specific polymer preferably has a reactive group that reacts with a crosslinking agent described later.
The specific polymer preferably has a particle shape. That is, it is preferable that the conductive thin wire contains particles of the specific polymer.
The specific polymer is preferably a polymer (a copolymer) represented by General Formula (1) below.
—(A)x—(B)y—(C)z—(D)w— General Formula (1)
In General Formula (1), A, B, C, and D respectively represent repeating units represented by General Formulae (A) to (D).
R11 represents a methyl group or a halogen atom, and it is preferably a methyl group, a chlorine atom, or a bromine atom. p represents an integer of 0 to 2, and it is preferably 0 or 1 and more preferably 0.
R12 represents a methyl group or an ethyl group, and it is preferably a methyl group.
R13 represents a hydrogen atom or a methyl group, and it is preferably a hydrogen atom. L represents a divalent linking group, and it is preferably a group represented by General Formula (2).
—(CO—X1)r—X2— General Formula (2)
In General Formula (2), X1 represents an oxygen atom or NR30—. Here, R30 represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group, each of which may have a substituent (for example, a halogen atom, a nitro group, or a hydroxyl group). R30 is preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, an n-butyl group, or an n-octyl group), or an acyl group (for example, an acetyl group or a benzoyl group). X1 is preferably an oxygen atom or —NH—.
X2 represents an alkylene group, an arylene group, an alkylene arylene group, an arylene alkylene group, or an alkylene arylene alkylene group, and in the middle of these groups, —O—, —S—, —CO—, —COO—, —NH—, —SO2—, —N(R31)—, or —N(R31)SO2— may be inserted. R31 represents a linear or branched alkyl group having 1 to 6 carbon atoms. X2 is preferably a dimethylene group, a trimethylene group, a tetramethylene group, an o-phenylene group, an m-phenylene group, a p-phenylene group, —CH2CH2OCOCH2CH2—, or —CH2CH2OCO(C6H4)—.
r represents 0 or 1.
q represents 0 or 1, and it is preferably 0.
R14 represents an alkyl group, an alkenyl group, or an alkynyl group, and it is preferably an alkyl group having 5 to 50 carbon atoms, more preferably an alkyl group having 5 to 30 carbon atoms, and still more preferably an alkyl group having 5 to 20 carbon atoms.
R15 represents a hydrogen atom, a methyl group, an ethyl group, a halogen atom, or —CH2COOR16, and it is preferably a hydrogen atom, a methyl group, a halogen atom, or —CH2COOR16, more preferably a hydrogen atom, a methyl group, or —CH2COOR16, and still more preferably a hydrogen atom.
R16 represents a hydrogen atom or an alkyl group having 1 to 80 carbon atoms and may be the same as or different from R14. R16 preferably has 1 to 70 carbon atoms and more preferably 1 to 60 carbon atoms.
In General Formula (1), x, y, z, and w represent a molar ratio of each repeating unit.
x is 3% to 60% by mole, and it is preferably 3% to 50% by mole and more preferably 3% to 40% by mole.
y is 30% to 96% by mole, and it is preferably 35% to 95% by mole and more preferably 40% to 90% by mole.
z is 0.5% to 25% by mole, and it is preferably 0.5% to 20% by mole and more preferably 1% to 20% by mole.
w is 0.5% to 40% by mole, and it is preferably 0.5% to 30% by mole.
In General Formula (1), a preferred case is a case where x is 3% to 40% by mole, y is 40% to 90% by mole, z is 0.5% to 20% by mole, and w is 0.5% to 10% by mole.
The polymer represented by General Formula (1) is preferably a polymer represented by General Formula (2).
In General Formula (2), x, y, z, and w are as defined above.
The polymer represented by General Formula (1) may contain a repeating unit other than the repeating units represented by General Formulae (A) to (D) described above.
Examples of the monomers for forming other repeating units include acrylic acid esters, methacrylic acid esters, vinyl esters, olefins, crotonic acid esters, itaconic acid diesters, maleic acid diesters, fumaric acid diesters, acrylamides, unsaturated carboxylic acids, allyl compounds, vinyl ethers, vinyl ketones, vinyl heterocyclic compounds, glycidyl esters, and unsaturated nitriles. These monomers are also described in paragraphs 0010 to 0022 of JP3754745B. From the viewpoint of hydrophobicity, acrylic acid esters or methacrylic acid esters are preferable, and a hydroxyalkyl methacrylate or a hydroxyalkyl acrylate is more preferable.
The polymer represented by General Formula (1) preferably contains a repeating unit represented by General Formula (E).
In the formula described above, LE represents an alkylene group, and it is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 2 to 6 carbon atoms, and still more preferably an alkylene group having 2 to 4 carbon atoms.
The polymer represented by General Formula (1) is particularly preferably a polymer represented by General Formula (3).
In the above formula described above, a1, b1, c1, d1, and e1 represent the molar ratio of each repeating unit, a1 represents 3 to 60 (% by mole), b1 represents 30 to 95 (% by mole), c1 represents 0.5 to 25 (% by mole), d1 represents 0.5 to 40 (% by mole), and e1 represents 1 to 10 (% by mole).
The preferred range of a1 is the same as the preferred range of the x described above, the preferred range of b1 is the same as the preferred range of the y described above, the preferred range of c1 is the same as the preferred range of the z described above, and the preferred range of d1 is the same as the preferred range of the w described above.
e1 is 1% to 10% by mole, and it is preferably 2% to 9% by mole and more preferably 2% to 8% by mole.
The specific polymer can be synthesized with reference to, for example, JP3305459B and JP3754745B.
The weight-average molecular weight of the specific polymer is not particularly limited, and it is preferably 1,000 to 1,000,000, more preferably 2,000 to 750,000, and still more preferably 3,000 to 500,000.
The conductive thin wire may contain other materials other than the above-described material, as necessary.
Examples thereof include an antistatic agent, a nucleation accelerator, a spectral sensitizing dye, a surfactant, an antifogging agent, a film hardening agent, a black pepper spot preventing agent, a redox compound, a monomethine compound, and dihydroxybenzenes as described in paragraphs 0220 to 0241 of JP2009-004348A. Further, the conductive thin wire may contain a physical development nucleus.
In addition, the conductive thin wire may contain a crosslinking agent that is used for crosslinking the above-described specific polymers to each other. In a case where a crosslinking agent is contained, the crosslinking between the specific polymers proceeds, and thus the linking between the metals in the conductive thin wire is maintained.
A line width Wa of the conductive thin wire 14 is the maximum length of the region where metallic silver 15 of the conductive thin wire 14 is present in the direction DW orthogonal to the direction DL in which the conductive thin wire 14 extends (see
The line width Wa of the above-described conductive thin wire 14 is obtained by selecting any five positions corresponding to the line width of one conductive thin wire using a scanning electron microscope and calculating an arithmetic average value of the line widths at the five positions.
A height T of the conductive thin wire is the maximum length of the region where the metallic silver 15 of the conductive thin wire 14 is present in the direction perpendicular to the surface 12a of the substrate 12. The height T of the conductive thin wire 14 is not particularly limited; however, it is preferably 0.06 μm or more and less than 7.5 μm, and more preferably 0.3 to 3.0 μm, from the viewpoint of the balance between the conductivity and the bendability.
The height T of the above-described conductive thin wire 14 is obtained by selecting any five positions corresponding to the heights of one conductive thin wire using a scanning electron microscope and calculating an arithmetic average value of the portions corresponding to the heights of the five positions
From the viewpoint of the conductivity of the conductive thin wire 14 and the difficulty in causing disconnection or the like due to the influence of surface pressure of a roll, a ratio (aspect ratio) of the height T of the conductive thin wire 14 to the line width Wa of the conductive thin wire 14 in the vertical cross section Ac is preferably 0.3 to 2.5, more preferably 0.6 or more and less than 1.5, and still more preferably 0.8 or more and less than 1.3.
A line resistance value of the conductive thin wire is preferably lower than 100 Ω/mm. In particular, from the viewpoint of operability for use as a touch panel, the line resistance value is more preferably lower than 80 Ω/mm and still more preferably lower than 60 Ω/mm.
The line resistance value is a value obtained by dividing a resistance value measured by the four point probe method, by a distance between measurement terminals. A more specific measuring method for the line resistance value will be described in Examples which will be described later.
The conductive thin wire may form a predetermined pattern. That is, the conductive substrate may have a pattern formed from the conductive thin wires.
The pattern that is formed from the conductive thin wire is not particularly limited, and examples thereof include a triangle such as an equilateral triangle, an isosceles triangle, or a right angled triangle, a quadrangle such as a square, a rectangle, a rhombus, a parallelogram, or a trapezoid, a (regular) n-polygon such as a (regular) hexagon or a (regular) octagon, a circle, an ellipse, a star shape, and a geometric figure obtained by combining these figures.
In addition, the pattern that is formed from the conductive thin wire is more preferable to be a mesh shape (mesh pattern).
As illustrated in
In
The length L of one side of the opening portion 18 is not particularly limited, and it is preferably 1,500 μm or less, more preferably 1,300 μm or less, and still more preferably 1,000 μm or less. In addition, the length L of one side of the opening portion 18 is preferably 5 μm or more, more preferably 30 μm or more, and still more preferably 80 μm or more. In a case where the length of the side of the opening portion is in the above range, it is possible to further maintain good transparency, and in a case where the conductive substrate is attached to the front surface of a display device, it is possible to visually recognize the display without an uncomfortable feeling.
From the viewpoint of visible light transmittance, an opening ratio of the mesh pattern is preferably 90.00% or more, more preferably 95.00% or more, and still more preferably 99.50% or more. The upper limit thereof is not particularly limited; however, it may be less than 100%.
The opening ratio corresponds to a proportion of a region on the substrate, excluding a region in which the conductive thin wire is present, to the entire region of the mesh pattern region.
Next, a manufacturing method for a conductive substrate will be described.
The manufacturing method for the conductive substrate is not particularly limited as long as the conductive substrate having the above-described configuration can be manufactured, and examples thereof include a manufacturing method including the following step 1 and step 2 in this order.
In the manufacturing method, a conductive thin wire containing silver can be formed, for example, by carrying out at least one of a step 1a of forming a thin wire-shaped silver-containing layer containing silver, as the thin wire-shaped metal-containing layer, or a step 2a of subjecting the metal-containing layer to an electroless silver plating treatment.
Hereinafter, the procedure of each step will be described in detail.
The step is a step 1 of forming a thin wire-shaped metal-containing layer on the substrate. By this step, a thin wire-shaped metal-containing layer that is subjected to the plating treatment is formed.
The substrate that is used in this step is as described above.
Examples of the kind of the metal include silver, copper, gold, nickel, and palladium, where silver or copper is preferable, and silver is more preferable. That is, it is preferable that the step 1 is a step la of forming a thin wire-shaped silver-containing layer containing silver, as the thin wire-shaped metal-containing layer.
The metal may have a particle shape, and in such a case, the average particle diameter of the metal particles (preferably, silver particles) is preferably 10 to 1,000 nm, more preferably 10 to 200 nm, and still more preferably 50 to 150 nm, in terms of sphere equivalent diameter.
The shape of the metal particle is not particularly limited, and examples thereof include a spherical shape, a cubic shape, a flat plate shape (a hexagonal flat plate shape, a triangular flat plate shape, a quadrangular flat plate shape, or the like), an octahedron shape, and a tetradecahedron shape.
The metal content in the thin wire is not particularly limited, and it is preferably 3.0 to 20.0 g/m2 from the viewpoint that the conductivity of the conductive substrate is more excellent.
It is preferable that the thin wire-shaped metal-containing layer contains a polymer. That is, in the thin wire-shaped metal-containing layer, it is preferable that the metal is dispersed in a polymer, where the polymer serves as a binder.
The kind of the polymer is not particularly limited; however, a specific polymer is preferable from the viewpoint that a conductive thin wire having more excellent strength can be formed. The specific polymer is as described above, including a preferred aspect thereof.
The content of the polymer in the thin wire-shaped metal-containing layer is not particularly limited, and it is preferably 0.005 to 2.0 g/m2 and more preferably 0.01 to 1.0 g/m2 from the viewpoint that the effect of the present invention is more excellent.
A method of forming the thin wire-shaped metal-containing layer on the substrate is not particularly limited, and a publicly known method is employed. Examples thereof include a method of carrying out exposure and development using a silver halide, a method of forming a layer containing silver on the entire surface of a substrate and then removing a part of the layer using a resist pattern to form a thin wire-shaped silver-containing layer, and a method of ejecting a composition containing metal-containing particles and a polymer onto a base material by a publicly known printing method such as inkjet to form a thin wire-shaped metal-containing layer.
Among these, a method of carrying out exposure and development using a silver halide is preferable from the viewpoint that a conductive substrate having a more excellent effect of the present invention can be manufactured.
The method of carrying out exposure and development using a silver halide preferably has the following steps.
Hereinafter, the procedure of each step will be described in detail.
The step A is a step of forming, on a substrate, a silver halide-containing photosensitive layer (hereinafter, also referred to as a “photosensitive layer”) containing a silver halide, gelatin, and a specific polymer. By this step, a substrate having a photosensitive layer that is subjected to an exposure treatment described later is manufactured.
First, a material which is used in the step A will be described in detail, and then the procedure of the step A will be described in detail.
A halogen atom contained in the silver halide may be any one of a chlorine atom, a bromine atom, an iodine atom, or a fluorine atom, and a combination thereof may be contained. For example, a silver halide mainly formed of silver chloride, silver bromide, or silver iodide is preferable, and a silver halide mainly formed of silver chloride or silver bromide is more preferable. It is noted that silver chlorobromide, silver iodochlorobromide, or silver iodobromide is also preferably used.
Here, for example, the “silver halide mainly composed of silver chloride” means a silver halide in which the molar fraction of ions of chlorides to the total halide ions in the silver halide composition is 50% or more. This silver halide mainly composed of silver chloride may contain a bromide ion and/or an iodide ion in addition to the chloride ion.
The silver halide generally has a solid particle shape, and the average particle diameter of the silver halide is preferably 10 to 1,000 nm, more preferably 10 to 200 nm, and still more preferably 50 to 150 nm, in terms of sphere equivalent diameter.
The shape of the particle of the silver halide is not particularly limited, and examples thereof include a spherical shape, a cubic shape, a flat plate shape (a hexagonal flat plate shape, a triangular flat plate shape, a quadrangular flat plate shape, or the like), an octahedron shape, and a tetradecahedron shape.
The kind of gelatin is not particularly limited, and examples thereof include lime-treated gelatin and acid-treated gelatin. In addition, a hydrolyzate of gelatin, an enzymatic decomposition product of gelatin, or gelatin modified with an amino group and/or a carboxyl group (phthalated gelatin or acetylated gelatin) may be used.
The photosensitive layer contains a polymer (a specific polymer) different from gelatin. Since this specific polymer is contained in the photosensitive layer, the strength of the silver-containing layer and the conductive thin wire, which are formed from the photosensitive layer, is more excellent.
The kind, the specific example, and the characteristics of the specific polymer, such as the shape, are as described above.
The photosensitive layer may contain other materials other than the above-described material, as necessary.
Examples of the other materials include metal compounds belonging to Groups 8 and 9, such as a rhodium compound and an iridium compound that are used for stabilizing the silver halide and increasing the sensitivity of the silver halide. In addition, examples of the other materials include other materials which may be contained in the conductive thin wire.
These materials other than the gelatin and the specific polymer may be contained in the silver halide-free layer and/or the protective layer described later.
A method of forming a photosensitive layer in the step A, which contains the above-described components, is not particularly limited; however, from the viewpoint of productivity, it is preferably a method of bringing a composition for forming a photosensitive layer, containing a silver halide, gelatin, and the specific polymer, into contact with a substrate and forming a photosensitive layer on the substrate.
The composition for forming a photosensitive layer contains the above-described silver halide, gelatin, and specific polymer. It is noted that, as necessary, the specific polymer may be contained in the composition for forming a photosensitive layer in the form of a particle shape.
The composition for forming a photosensitive layer may contain a solvent, as necessary.
Examples of the solvent include water, organic solvents (for example, alcohols, ketones, amides, sulfoxides, esters, and ethers), ionic liquids, and mixed solvents thereof.
A method of bringing the composition for forming a photosensitive layer into contact with a substrate is not particularly limited, and examples thereof include a method of applying the composition for forming a photosensitive layer onto a substrate and a method of immersing a substrate in the composition for forming a photosensitive layer.
After the above-described treatment, a drying treatment may be carried out as necessary.
The photosensitive layer formed according to the above procedure contains a silver halide, gelatin, and the specific polymer.
The content of the silver halide in the photosensitive layer is not particularly limited and, from the viewpoint that the effect of the present invention is more excellent, it is preferably 3.0 to 20.0 g/m2 and more preferably 5.0 to 15.0 g/m2 in terms of silver.
“In terms of silver” means that all the silver halides are converted into the mass of silver to be generated by reducing all the silver halides.
The content of the specific polymer in the photosensitive layer is not particularly limited and, from the viewpoint that the effect of the present invention is more excellent, it is preferably 0.04 to 2.0 g/m2 and more preferably 0.08 to 0.40 g/m2.
The step B is a step of exposing the photosensitive layer and then subjecting it to a development treatment to form a thin wire-shaped silver-containing layer containing metallic silver, gelatin, and a specific polymer.
In a case where the photosensitive layer is subjected to an exposure treatment, a latent image is formed in the exposed region.
The exposure may be carried out in a patterned manner. In order to obtain a mesh pattern consisting of the conductive thin wire described above, examples of the exposure method include a method of carrying out exposure through a mask having a mesh-shaped opening pattern and a method of carrying out exposure in a mesh shape by carrying out scanning using laser light.
The kind of light that is used for exposure is not particularly limited as long as a latent image can be formed on the silver halide, and examples thereof include visible light, ultraviolet rays, and X-rays.
In a case where exposure is carried out through a mask having an opening pattern, the exposure amount may be reduced and only a specific place in the mask opening pattern may be exposed to adjust the amount of latent image formation. In a case where the amount of latent image formation is adjusted, it is possible to adjust the amount and thickness (height) of the metal which is formed in the subsequent operation. The means for reducing the exposure amount only in the specific place is not particularly limited, and examples thereof include a method of adjusting the exposure amount from a light source, with which the specific portion is irradiated. For example, it includes such a method as reducing the exposure amount by reducing the output of only the lamp and LED above the portion of interest or installing a dimming filter above the specific portion. In addition, examples of another means for reducing the exposure amount only in the specific place include a method using a halftone mask in which a semi-transmissive film is applied to a specific portion of the mask opening pattern. From the viewpoint of productivity, it is preferable to use a halftone mask.
In a case where the exposed photosensitive layer is subjected to a development treatment, metallic silver is precipitated in the exposed region (the region in which a latent image is formed).
The method of the development treatment is not particularly limited, and examples thereof include publicly known methods that are used for a silver salt photographic film, photographic printing paper, a printing plate making film, and an emulsion mask for a photomask.
In the development treatment, a developer is generally used. The kind of developer is not particularly limited, and examples thereof include a phenidone hydroquinone (PQ) developer, a metol hydroquinone (MQ) developer, and a metol/ascorbic acid (MAA) developer.
This step may further include a fixing treatment that is carried out for the purpose of removing and stabilizing the silver halide of unexposed portions.
The fixing treatment is carried out simultaneously with development and/or after development. The method of the fixing treatment is not particularly limited, and examples thereof include methods that are used for a silver salt photographic film, photographic printing paper, a printing plate making film, and an emulsion mask for a photomask.
In the fixing treatment, a fixing liquid is generally used. The kind of fixing liquid is not particularly limited, and examples thereof include the fixing liquid described in “Chemistry of Photographs” (written by Sasai, Photo Industry Publishing Co., Ltd.) p321.
In a case where the above-described treatment is carried out, a thin wire-shaped silver-containing layer containing metallic silver, gelatin, and the specific polymer is formed.
Examples of the method of adjusting the width of the silver-containing layer include a method of adjusting the opening width of a mask that is used at the time of exposure.
In addition, in a case where a mask is used at the time of exposure, the width of the silver-containing layer to be formed can be adjusted by adjusting the exposure amount. For example, in a case where the opening width of the mask is narrower than the target width of the silver-containing layer, the width of the region in which a latent image is formed can be adjusted by increasing the exposure amount more than usual.
Further, in a case where laser light is used, the exposed region can be adjusted by adjusting the focusing range and/or the scanning range of the laser light.
The step C is a step of subjecting the silver-containing layer obtained in the step B to a heating treatment. In a case where this step is carried out, fusion welding between specific polymers in the silver-containing layer progresses, and thus the strength of the silver-containing layer is improved.
The method of the heating treatment is not particularly limited, and examples thereof include a method of bringing the silver-containing layer into contact with superheated vapor and a method of heating the silver-containing layer with a temperature control device (for example, a heater), and a method of bringing the silver-containing layer into contact with superheated vapor is preferable.
The superheated vapor may be superheated steam or may be a mixture obtained by mixing superheated steam with another gas.
The time of contact between the superheated vapor and the silver-containing layer is not particularly limited, and it is preferably 10 to 70 seconds.
The supply amount of the superheated vapor is preferably 500 to 600 g/m3, and the temperature of the superheated vapor is preferably 100° C. to 160° C. and more preferably 100° C. to 120° C. at 1 atm.
Preferable heating conditions in the method of heating the silver-containing layer in a temperature control device are 100° C. to 200° C. (more preferably 100° C. to 150° C.) and 1 to 240 minutes (more preferably 60 to 150 minutes).
The step D is a step of removing gelatin in the silver-containing layer obtained in the step C to form the thin wire-shaped silver-containing layer. In a case where this step is carried out, gelatin is removed from the silver-containing layer, and the thin wire-shaped silver-containing layer having voids formed inside thereof is formed. A plating treatment liquid described later permeates into the void, and metal plating is formed.
In a case where gelatin is removed, all of the gelatin in the silver-containing layer may be removed, or the gelatin may be removed so that a part thereof remains.
The method of removing gelatin is not particularly limited, and examples thereof include a method of using a proteolytic enzyme (hereinafter, also referred to as a “method 1”) and a method of decomposing and removing gelatin using an oxidizing agent (hereinafter, also referred to as a “method 2”).
Examples of the proteolytic enzyme that is used in the method 1 include enzymes publicly known as vegetable or animal enzymes that are capable of hydrolyzing proteins such as gelatin.
Examples of the proteolytic enzyme include pepsin, rennin, trypsin, chymotrypsin, cathepsin, papain, ficin, thrombin, renin, collagenase, bromelain, and a bacterial protease, and trypsin, papain, ficin, or a bacterial protease is preferable.
A method of bringing the silver-containing layer into contact with the above-described proteolytic enzyme suffices as the procedure in the method 1, and examples thereof include a method of bringing the silver-containing layer into contact with a treatment liquid (hereinafter, also referred to as an “enzyme solution”) containing a proteolytic enzyme. Examples of the contact method include a method of immersing the silver-containing layer in the enzyme solution and a method of applying the enzyme solution onto the silver-containing layer.
The content of the proteolytic enzyme in the enzyme solution is not particularly limited, and it is preferably 0.05% to 20% by mass and more preferably 0.5% to 10% by mass with respect to the total amount of the enzyme solution from the viewpoint that degree of decomposition and removal of the gelatin is easily controlled.
The enzyme solution generally contains water in addition to the above-described proteolytic enzyme.
As necessary, the enzyme solution may contain other additives (for example, a pH buffering agent, an antibacterial compound, a wetting agent, and a preservative).
The pH of the enzyme solution is selected so that the action of the enzyme can be obtained to the maximum; however, in general, it is preferably 5 to 9.
The temperature of the enzyme solution is preferably a temperature at which the action of the enzyme is enhanced, specifically, 20° C. to 45° C.
As necessary, a washing treatment in which the obtained silver-containing layer is washed with warm water after the treatment with the enzyme solution may be carried out.
The washing method is not particularly limited, and a method of bringing the silver-containing layer into contact with warm water is preferable. Examples thereof include a method of immersing the silver-containing layer in warm water and a method of applying warm water onto the silver-containing layer.
Regarding the temperature of the warm water, an optimum temperature is appropriately selected according to the kind of proteolytic enzyme to be used, and it is preferably 20° C. to 80° C. and more preferably 40° C. to 60° C. from the viewpoint of productivity.
The time (the washing time) of contact between the warm water and the silver-containing layer is not particularly limited, and it is preferably 1 to 600 seconds and more preferably 10 to 180 seconds from the viewpoint of productivity.
The oxidizing agent that is used in the method 2 may be any oxidizing agent capable of decomposing gelatin, and an oxidizing agent having a standard electrode potential of +1.5 V or higher is preferable. It is noted that the standard electrode potential is intended to be a standard electrode potential (25° C., E0) of the oxidizing agent with respect to the standard hydrogen electrode in the aqueous solution.
Examples of the oxidizing agent include persulfuric acid, percarbonic acid, perphosphoric acid, hypoperchloric acid (HClO5), peracetic acid, metachloroperbenzoic acid, hydrogen peroxide water, perchloric acid, periodic acid, potassium permanganate, ammonium persulfate, ozone, and hypochlorous acid or a salt thereof. Among these, in terms of productivity and economy, hydrogen peroxide water (standard electrode potential: 1.76 V), or hypochlorous acid or a salt thereof is preferable, and sodium hypochlorite is more preferable.
A method of bringing the silver-containing layer into contact with the above-described oxidizing agent suffices as the procedure in the method 2, and examples thereof include a method of bringing the silver-containing layer into contact with a treatment liquid (hereinafter, also referred to as an “oxidizing agent solution”) containing an oxidizing agent. Examples of the contact method include a method of immersing the silver-containing layer in the oxidizing agent solution and a method of applying the oxidizing agent solution onto the silver-containing layer.
The kind of solvent contained in the oxidizing agent solution is not particularly limited, and examples thereof include water and an organic solvent.
The step 1 may have a step E of forming a silver halide-free layer containing gelatin and the specific polymer on the substrate before the step A. In a case where this step is carried out, a silver halide-free layer is formed between the substrate and the silver halide-containing photosensitive layer. This silver halide-free layer serves as a so-called antihalation layer and contributes to improving the adhesiveness between the conductive thin wire and the substrate.
The silver halide-free layer contains the above-described gelatin and specific polymer. On the other hand, the silver halide-free layer does not contain a silver halide.
The ratio of the mass of the specific polymer to the mass of the gelatin (the mass of the specific polymer/the mass of the gelatin) in the silver halide-free layer is not particularly limited, and it is preferably 0.1 to 5.0 and more preferably 1.0 to 3.0.
The content of the specific polymer in the silver halide-free layer is not particularly limited. It is 0.03 g/m2 or more in a large number of cases, and it is preferably 1.0 g/m2 or more from the viewpoint that the adhesiveness of the conductive thin wire is more excellent. The upper limit thereof is not particularly limited and is 1.63 g/m2 or less in a large number of cases.
A method of forming the silver halide-free layer is not particularly limited, and examples thereof include a method of applying a composition for forming a layer, containing gelatin and the specific polymer, onto a substrate and carrying out a heating treatment as necessary.
For example, the composition for forming a layer may contain a solvent as necessary. Examples of the kind of solvent include the solvent that is used in the above-described composition for forming a photosensitive layer.
The thickness of the silver halide-free layer is not particularly limited. It is 0.05 μm or more in a large number of cases, and it is preferably more than 1.0 μm and more preferably 1.5 μm or more from the viewpoint that the adhesiveness of the conductive thin wire is more excellent. The upper limit thereof is not particularly limited; however, it is preferably less than 3.0 μm.
The step 1 may have a step F of forming a protective layer containing gelatin and the specific polymer on the silver halide-containing photosensitive layer after the step A and before the step B. In a case where a protective layer is provided, it is possible to prevent scratches on the photosensitive layer and improve the mechanical characteristics.
The ratio of the mass of the specific polymer to the mass of the gelatin (the mass of the specific polymer/the mass of the gelatin) in the protective layer is not particularly limited, and it is preferably more than 0 and 2.0 or less, and more preferably more than 0 and 1.0 or less.
In addition, the content of the specific polymer in the protective layer is not particularly limited, and it is preferably more than 0 g/m2 and 0.3 g/m2 or less, and more preferably 0.005 to 0.1 g/m2.
A method of forming the protective layer is not particularly limited, and examples thereof include a method of applying a composition for forming a protective layer, containing gelatin and the specific polymer, onto the silver halide-containing photosensitive layer and carrying out a heating treatment as necessary.
For example, the composition for forming a protective layer may contain a solvent as necessary. Examples of the kind of solvent include the solvent that is used in the above-described composition for forming a photosensitive layer.
The thickness of the protective layer is not particularly limited, and it is preferably 0.03 to 0.3 μm and more preferably 0.075 to 0.20 μm.
The above-described step E, step A, and step F may be simultaneously carried out by simultaneous multilayer coating.
It is preferable that the manufacturing method for the conductive substrate includes, after the step 1 and before the step 2, a step G of bringing the thin wire-shaped metal-containing layer (hereinafter, also simply referred to as a “thin wire”) formed on the substrate by the step 1 into contact with a solution containing an organic acid. The step G allows the organic acid to adhere to the surface of the thin wire and suppresses the plating precipitation on the surface of the thin wire in a plating treatment in a step 2 described later, whereby the plating treatment liquid is more likely to permeate into the inside of the thin wire. As a result, the metal (the plated metal) is easily precipitated in the inside of the thin wire, and thus a desired effect can be obtained.
The kind of the organic acid contained in the solution containing the organic acid (hereinafter, also simply referred to as a “first solution”) is not particularly limited as long as the organic acid contains carbon atoms, and examples thereof include a carboxylic acid (an organic compound having a carboxy group), a sulfonic acid (an organic compound having a sulfonate group), and phosphonic acid (an organic compound having a phosphonate group). Among these, a carboxylic acid is preferable.
The molecular weight of the organic acid (for example, a carboxylic acid) is not particularly limited; however, it is preferably 60 to 400 and more preferably 90 to 300.
The carboxylic acid may be a monovalent carboxylic acid or may be a divalent or higher-valent (polyvalent) carboxylic acid, and it is preferably a polyvalent carboxylic acid. The divalent or higher-valent carboxylic acid is preferably a divalent to heptavalent carboxylic acid, and more preferably a divalent to tetravalent carboxylic acid.
Here, the valence represents the number of carboxy groups contained, and the monovalent carboxylic acid is a compound having one carboxy group.
The carboxylic acid may have a polar group (for example, a hydroxy group, an amino group, a carbonyl group, or an ether group) in addition to the carboxy group.
Examples of the carboxylic acid include monovalent carboxylic acids such as acetic acid, lactic acid, and hydroxybutyric acid, divalent carboxylic acid such as oxalic acid, malonic acid, tartaric acid, L-aspartic acid, DL-malic acid, oxaloacetic acid, succinic acid, glutamic acid, and 2-oxoglutaric acid, glutaric acid, adipic acid, and pimelic acid, trivalent carboxylic acids such as citric acid, 1,2,3-propanetricarboxylic acid, and 1,3,5-pentatricarboxylic acid, tetravalent carboxylic acids such as 1,2,3,4-butane tetracarboxylic acid, ethylenediamine tetraacetic acid, and ethylene glycol bis(β-aminoethyl ether)-N,N,N,N-tetraacetic acid, and pentavalent carboxylic acids such as diethylenetriamine pentaacetic acid.
The first solution contains a solvent. The kind of solvent is not particularly limited, and examples of the solvent include water, organic solvents (for example, alcohols, ketones, amides, sulfoxides, esters, and ethers), ionic liquids, and mixed solvents thereof. Among them, water is preferable.
The content of the organic acid in the first solution is not particularly limited; however, it is preferably 0.2% to 5% by mass and more preferably 0.5% to 3% by mass with respect to the total mass of the first solution.
The pH value of the first solution is not particularly limited; however, it is preferably 1.5 to 6.0 and more preferably 2.0 to 4.0 at a temperature of 25° C.
Regarding a measuring method for pH, the measurement can be carried out with a pH meter using a pH electrode.
A method of bringing the thin wire into contact with the first solution is not particularly limited, and examples thereof include a method of immersing a substrate having the thin wire in the first solution and a method of applying the first solution onto the thin wire.
The time of contact between the thin wire and the first solution is not particularly limited, and it is preferably 5 to 180 seconds and more preferably 20 to 120 seconds from the viewpoint of productivity.
The temperature of the first solution at the time of contact between the thin wire and the first solution is not particularly limited; however, it is preferably 30° C. to 100° C. and more preferably 65° C. to 95° C.
After bringing the thin wire into contact with the first solution, the thin wire may be washed with a solvent (for example, water), as necessary.
The step 2 is a step of subjecting the thin wire-shaped metal-containing layer to an electroless plating treatment to form the conductive thin wire. In a case where this step is carried out, a metal is precipitated on the surface and in the inside of the thin wire-shaped metal-containing layer. In particular, in the thin wire-shaped silver-containing layer obtained by carrying out the above-described steps A to D, there is a space formed by removing gelatin. Therefore, a thin conductive thin wire filled with metal is formed in this space.
As the electroless plating treatment that is carried out in this step, a publicly known electroless plating technique (chemical reduction plating or substitution plating) is used. As the electroless plating treatment, a publicly known electroless plating technique is used.
Examples of the metal species that are used for the plating treatment include silver, copper, nickel, and cobalt, where silver or copper is preferable, and silver is more preferable, from the viewpoint that the effect of the present invention is more excellent.
That is, the step 2 of subjecting the metal-containing layer to an electroless plating treatment is preferably a step of carrying out an electroless silver plating treatment or an electroless copper plating treatment and more preferably a step 2a of carrying out an electroless silver plating treatment from the viewpoint that the effect of the present invention is more excellent.
Examples of the plating treatment liquid (hereinafter, also simply referred to as a “plating liquid”) which is used for the electroless plating treatment include a plating liquid containing a solvent, a metal ion, a reducing agent, and potassium iodide.
Water is preferable as the solvent that is contained in the plating liquid.
The content of the solvent in the plating liquid is not particularly limited; however, it is preferably 60% to 95% by mass and more preferably 80% to 90% by mass with respect to the total mass of the plating liquid.
The kind of the metal ion contained in the plating liquid can be appropriately selected according to the metal species that is desired to be precipitated. Examples thereof include a silver ion, a copper ion, a nickel ion, and a cobalt ion, where a silver ion or a copper ion is preferable, and a silver ion is more preferable.
The metal ion in the plating liquid is derived from, for example, a metal salt added to the plating liquid. The kind of the metal salt that is added to the plating liquid is not particularly limited, and a publicly known metal salt can be used.
As the metal salt, a water-soluble metal salt is preferable. The water-soluble metal salt means a metal salt, 0.1% by mass or more of which is dissolved in water.
The metal salt is preferably a silver salt or a copper salt, and more preferably a silver salt.
Examples of the silver salt include an inorganic silver salt and an organic silver salt, and an inorganic silver salt is preferable.
Examples of the inorganic silver salt include silver nitrate, silver fluoride, silver chlorate, and silver sulfate.
The content of the silver salt in the plating liquid is not particularly limited, and it is preferably 0.01 to 5.0 mol/L and more preferably 0.05 to 3.0 mol/L with respect to the total amount of the plating liquid.
Only one kind of the silver salt may be used, or two or more kinds thereof may be used in combination.
It is noted that the silver contained in the silver salt is ionized in the plating liquid to become a silver ion.
The kind of the reducing agent contained in the plating liquid is not particularly limited, and a publicly known reducing agent can be used.
Examples of the reducing agent include an ascorbic acid compound such as ascorbic acid or isoascorbic acid, or a salt thereof; a hydrazine such as hydrazine, hydrazine monohydrate, hydrazine sulfate, or hydrazine chloride, or a salt thereof; a hydroquinone such as hydroquinone or methyl hydroquinone, or a derivative thereof; and a pyrogallol such as pyrogallol, pyrogallol monomethyl ether, pyrogallol-4-carboxylic acid, pyrogallol-4,6-dicarboxylic acid, or gallic acid, or a derivative thereof.
The content of the reducing agent in the plating liquid is not particularly limited; however, it is preferably 2 mol/L or less, more preferably 0.1 mol/L or less, and still more preferably 0.06 mol/L (60 mmol/L) or less with respect to the total amount of the plating liquid. The lower limit value thereof is not particularly limited; however, it is preferably 0.01 mol/L (10 mmol/L) or more and more preferably 0.02 mol/L (20 mmol/L) or more with respect to the total amount of the plating liquid.
Only one kind of the reducing agent may be used, or two or more kinds thereof may be used in combination.
The plating liquid that is used for the electroless plating treatment contains potassium iodide.
The content of potassium iodide in the plating liquid is, for example, preferably 0.001 to 1 mmol/L and more preferably 0.01 to 0.1 mmol/L with respect to the total amount of the plating liquid.
In addition, from the viewpoint that it is easy to form a conductive thin wire having a ratio I/Ag in the above-described range, a ratio C calculated from the following expression (1) is preferably less than 5, more preferably less than 1, still more preferably less than 0.8, and particularly preferably 0.7 or less in a case where a content of potassium iodide in the plating liquid is defined as CKI mmol/L and a content of the reducing agent in the plating liquid is defined as CR mmol/L. The lower limit of the ratio C is not particularly limited; however, it is preferably 0.01 or more, more preferably 0.1 or more, and still more preferably 0.3 or more.
Ratio C=CKI/CR×1,000 (1)
In particular, from the viewpoint that it is easy to form a conductive thin wire having a ratio I/Ag in the above-described range, the plating liquid that is used for the electroless plating treatment is preferably such a plating liquid that contains potassium iodide and a reducing agent, where the content of the reducing agent in the plating liquid is 60 mmol/L or less with respect to the total amount of the plating liquid, and ratio C=CKI/CR×1,000≤0.7 is satisfied in a case where contents of the potassium iodide and the reducing agent in the plating treatment liquid are denoted as CKI mmol/L and CR mmol/L, respectively. The suitable ranges of the lower limit of the content of the reducing agent, the content of potassium iodide, and the lower limit of the ratio C are respectively as described above.
In the plating treatment liquid that is used for the electroless plating treatment, It is preferable that the content of potassium iodide and/or the reducing agent is adjusted so that it is included in the above-described preferred range of the content.
The plating liquid may contain components other than the above-described components. Examples of the other components include a stabilizer that improves the stability of a silver ion generated by the ionization of a silver salt, and a pH adjusting agent.
The pH of the plating liquid is not particularly limited; however, it is preferably an alkaline pH, more preferably 8.5 to 11.0, and still more preferably 9.0 to 10.5 at a temperature of 25° C., from the viewpoint that the effect of the present invention is more excellent.
The procedure of the above-described plating treatment is not particularly limited as long as it is a method of bringing the metal-containing layer into contact with the plating liquid, and examples thereof include a method of immersing the metal-containing layer in the plating liquid and a method of applying the plating liquid onto the metal-containing layer.
The time of contact between the metal-containing layer and the plating liquid is not particularly limited, and it is preferably 25 seconds to 30 minutes from the viewpoint of the more excellent effect of the present invention and the viewpoint of productivity.
After coming into contact with the plating liquid, the metal-containing layer may be washed with water or may be neutralized and washed with an acidic solution having a pH of 3 to 7. The pH of the acidic solution that is used for neutralization and washing is preferably 4 to 6. In a case where the acidic solution has a pH of 3 to 7, sulfur or the like is not generated from the sulfurous acid derived from the plating liquid. In addition, the increase in pH of the plating liquid is suppressed, and the plating reaction can be stopped. The acidic solution functions as a plating stop solution.
The acidic solution preferably has a buffering action, and the concentration of solid contents thereof is preferably 0.1% by mass or more since the acidic solution exhibits a sufficient buffering capacity.
The temperature of the plating liquid is preferably 10° C. to 40° C. and more preferably 15° C. to 30° C.
The contact time is not particularly limited, and it is preferably 5 to 60 seconds from the viewpoints of the more excellent effect of the present invention and productivity.
The manufacturing method for the conductive substrate may have steps other than the above-described step 1 and step 2.
The manufacturing method for a conductive substrate may further include a step 3 of subjecting the conductive thin wire obtained in the above-described step into a smoothing treatment.
In a case where this step is carried out, a conductive thin wire having more excellent conductivity can be obtained.
A method for the smoothing treatment is not particularly limited, and it is, for example, preferably a calender treatment step of causing a substrate having a conductive thin wire to pass between at least a pair of rolls under pressurization. Hereinafter, the smoothing treatment using a calender roll will be referred to as a calender treatment.
Examples of the roll that is used for the calender treatment include a plastic roll and a metal roll, where a plastic roll is preferable from the viewpoint of preventing wrinkles.
The pressure between the rolls is not particularly limited, and it is preferably 2 MPa or more and more preferably 4 MPa or more. In addition, the pressure between the rolls is preferably 120 MPa or less. It is noted that the pressure between rolls can be measured using PRESCALE (for high pressure) manufactured by FUJIFILM Corporation.
The smoothing treatment temperature is not particularly limited; however, it is preferably 10°° C. to 100° C. and more preferably 10° C. to 50° C.
The manufacturing method for a conductive substrate may include a step 3 of subjecting the conductive thin wire obtained in the above-described step to a heating treatment. In a case where this step is carried out, a conductive thin wire having more excellent conductivity can be obtained.
Examples of the heating treatment that is carried out in the step 3 include the heating treatment carried out in the step C described above.
The conductive substrate according to the present invention can be applied to various use applications, and for example, it can be applied to various use applications such as a touch panel (or a touch sensor), a semiconductor chip, various electrical wiring plates, flexible printed circuits (FPC), a chip on film (COF), tape automated bonding (TAB), an antenna, a multilayer interconnection board, and a motherboard. Among these, the conductive substrate according to the embodiment of the present invention is preferably used for a touch panel (a capacitance-type touch panel).
In a case where the conductive substrate according to the embodiment of the present invention is used for a touch panel, the above-described conductive thin wire can effectively function as a detection electrode.
In a case where the conductive substrate according to the embodiment of the present invention is used for a touch panel, examples of the display panel that is used in combination with the conductive substrate include a liquid crystal panel and an organic light emitting diode (OLED) panel, where a combination with an OLED panel is preferable.
In addition, the conductive substrate may have a conductive portion having a constitution different from that of the conductive thin wire, in addition to the conductive thin wire. This conductive portion may be electrically connected to the above-described conductive thin wire to conduct electricity. Examples of the conductive portion include a peripheral wire having a function of applying a voltage to the above-described conductive thin wire and an alignment mark for adjusting the position of a member to be laminated with that of the conductive substrate.
Examples of the use application of the conductive substrate according to the embodiment of the present invention other than those described above include an electromagnetic wave shield that blocks electromagnetic waves such as radio waves and microwaves (ultra-high frequency radio waves), generated from electronic apparatuses such as a personal computer and a workstation and prevents static electricity. Such an electromagnetic wave shield can be used not only for the main body of the personal computer but also for an electronic apparatus such as a videographing apparatus or an electronic medical apparatus.
The conductive substrate according to the embodiment of the present invention can also be used for a transparent exothermic body.
The conductive substrate according to the embodiment of the present invention may be used in the form of a laminate having a conductive substrate and other members such as a pressure-sensitive adhesive sheet and a peeling sheet during handling and transportation. The peeling sheet functions as a protective sheet for preventing the occurrence of scratching on the conductive substrate during the transportation of the laminate.
In addition, the conductive substrate may be handled in the form of a composite body having, for example, a conductive substrate, a pressure-sensitive adhesive sheet, and a protective layer in this order.
Basically, the present invention is constituted as described above. The conductive substrate according to the embodiment of the present invention has been described in detail; however, the present invention is not limited to the above-described embodiments, and various improvements or modifications may be made without departing from the gist of the present invention.
Hereinafter, the features of the present invention will be described in more detail with reference to Examples. The materials, the reagents, the amounts and ratios of substances, the operations, and the like described in the following Examples can be appropriately modified as long as they do not depart from the gist of the present invention. As a result, the scope of the present invention is not limited to the following Examples.
The following liquid 2 and liquid 3 were added simultaneously in amounts corresponding to 90% of an entire amount of each thereof over 20 minutes to the following liquid 1 kept at 30° C. and a pH of 4.5 while stirring the liquid 1, whereby nuclear particles having a size of 0.16 μm were formed. Subsequently, the following liquid 4 and liquid 5 were added over 8 minutes to the obtained solution, and the remaining 10% amount of each of the following liquid 2 and liquid 3 was further added over 2 minutes, whereby the nuclear particles grew to a size of 0.10 μm. Further, 0.15 g of potassium iodide was added to the obtained solution, which was subsequently aged for 5 minutes to complete particle formation.
This was followed by water washing using a flocculation method according to a conventional method. Specifically, the temperature of the obtained solution described above was decreased to 35° C. and the pH thereof was decreased (the pH thereof was in a range of 3.6±0.2) using sulfuric acid until silver halide was precipitated. Next, about 3 L of the supernatant solution was removed from the obtained solution (the first water washing). Next, 3 L of distilled water was added to the solution from which the supernatant solution had been removed, and then sulfuric acid was added thereto until the silver halide was precipitated. 3 L of the supernatant solution was removed again from the obtained solution (the second water washing). The same operation as the second water washing was repeated once more (the third water washing), whereby the water washing and desalting steps were completed. The emulsion after water washing and desalting was adjusted to have a pH of 6.4 and a pAg of 7.5, and then 2.5 g of gelatin, 10 mg of sodium benzenethiosulfonate, 3 mg of sodium benzenethiosulfinate, 15 mg of sodium thiosulfate, and 10 mg of chloroauric acid were added thereto, and chemosensitization was carried out at 55° C. so that the optimum sensitivity was obtained. Then, 100 mg of 1,3,3a,7-tetraazaindene as a stabilizer, and 100 mg of PROXEL (product name, manufactured by ICI Co., Ltd.) as a preservative were further added to the obtained emulsion. The finally obtained emulsion was an emulsion of cubic silver chlorobromide particles containing 0.08% by mole of silver iodide, where the rate of silver chlorobromide was such that 70% by mole for silver chloride and 30% by mole for silver bromide, and the average particle diameter (in terms of sphere equivalent diameter) was 100 nm and the coefficient of variation was 9%.
1,3,3a,7-tetraazaindene (1.2×10−4 mol/mol Ag), hydroquinone (1.2×10−2 mol/mol Ag), citric acid (3.0×10−4 mol/mol Ag), 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt (0.90 g/mol Ag), and a trace amount of a film hardening agent were added to the emulsion, thereby obtaining a composition. The pH of the composition was then adjusted to 5.6 using citric acid.
A polymer latex containing a polymer represented by (P-1) shown below (hereinafter, also referred to as a “polymer 1”), a dispersing agent consisting of a dialkylphenyl PEO (PEO is an abbreviation for polyethylene oxide) sulfuric acid ester, and water (in the polymer latex, the ratio of the mass of the dispersing agent to the mass of the polymer 1 (the mass of the dispersing agent/the mass of the polymer 1, unit: g/g) is 0.02, and the solid content is 22% by mass) was added to the above composition so that the ratio of the mass of the polymer 1 to the total mass of the gelatin in the composition (the mass of the polymer 1/the mass of the gelatin, unit: g/g) was 0.25/1, whereby a polymer latex-containing composition was obtained. Here, in the polymer latex-containing composition, the ratio of the mass of the gelatin to the mass of the silver derived from the silver halide (the mass of the gelatin/the mass of the silver derived from the silver halide, unit: g/g) was 0.11.
Further, EPOXY RESIN DY 022 (product name, manufactured by Nagase ChemteX Corporation) was added as a crosslinking agent. The adding amount of the crosslinking agent was adjusted so that the amount of the crosslinking agent in the silver halide-containing photosensitive layer which will be described later was 0.09 g/m2. Further, a surfactant 1 and a surfactant 2, which will be described later, and sodium polystyrene sulfonate (molecular weight: about 1 million) were added as a thickener.
In such a manner as described above, a composition for forming a photosensitive layer was prepared.
It is noted that the polymer 1 was synthesized with reference to JP3305459B and JP3754745B.
The above-described polymer latex was applied onto a polyethylene terephthalate film having a thickness of 40 μm (“a long roll-shaped film manufactured by FUJIFILM Corporation”) to provide an undercoat layer having a thickness of 0.05 μm. This treatment was carried out in a roll-to-roll manner, and each of the following treatments (steps) was also carried out in the same manner as the roll-to-roll manner. Here, the roll width was 1 m, and the roll length was 1,000 m.
Next, a composition for forming a silver halide-free layer, the above-described composition for forming a photosensitive layer, and a composition for forming a protective layer described later were simultaneously applied by multilayer coating onto the undercoat layer, and then a silver halide-free layer, a silver halide-containing photosensitive layer, and a protective layer were formed on the undercoat layer.
Here, the composition for forming a silver halide-free layer consisted of an aqueous solution containing the above-described polymer 1, gelatin, a solid dispersion of a dye described later, a surfactant 1, a surfactant 2, a surfactant 3, and sodium polystyrene sulfonate (molecular weight: about 1 million) as a thickener, the thickness of the silver halide-free layer was 2.0 μm, the mixing mass ratio of the polymer 1 to the gelatin in the silver halide-free layer (the polymer 1/the gelatin) was 2/1, and the content of the polymer 1 was 1.3 g/m2. In addition, the content of the dye was 0.08 g/m2, and the contents of the surfactant 1, the surfactant 2, the surfactant 3, and the thickener were respectively 0.02 g/m2, 0.02 g/m2, 0.02 g/m2, and 0.04 g/m2.
In addition, the thickness of the silver halide-containing photosensitive layer was 2.5μm, the mixing mass ratio of the polymer 1 to the gelatin in the silver halide-containing photosensitive layer (the polymer 1/the gelatin) was 0.25/1, and the content of the polymer 1 was 0.19 g/m2. In addition, the contents of the surfactant 1, the surfactant 2, and the thickener were respectively 0.04 g/m2, 0.01 g/m2, and 0.01 g/m2.
In addition, the composition for forming a protective layer consisted of an aqueous solution containing the above-described polymer 1, gelatin, colloidal silica (average particle diameter: 12 nm, manufactured by Nissan Chemical Corporation, SNOWTEX C), the surfactant 1, the surfactant 2, the surfactant 3, the surfactant 4, sodium polystyrene sulfonate (molecular weight: about 1 million) as a thickener, and N,N′-bis(vinylsulfonylacetyl)ethylenediamineethylene bis(vinylsulfonylacetamide) as a gelatin crosslinking agent,
The produced photosensitive layer described above was exposed through a lattice-shaped photomask using parallel light with a high-pressure mercury lamp as a light source. The mask for forming a pattern was used as a photomask, where the line width of the unit square lattice that forms the lattice as illustrated in
After exposure to light, the obtained sample was developed with a developer which will be described later, and further subjected to a development treatment using a fixing liquid (product name: N3X-R for CN16X, manufactured by FUJIFILM Corporation). Then, the sample was rinsed with pure water at 25° C. and subsequently dried to obtain a sample A having a silver-containing layer containing metallic silver, formed in a mesh patterned manner. In the sample A, a conductive mesh pattern region having a size of 21.0 cm×29.7 cm was formed.
The following compounds are contained in 1 liter (L) of the developer.
The obtained sample A described above was immersed in warm water at 50° C. for 180 seconds. Then, the sample A was drained with an air shower and allowed to be air-dried.
The sample A obtained in the step B-1 was carried into a superheated steam treatment tank at 110° C. and allowed to stand for 30 seconds for the superheated steam treatment. The steam flow rate at this time was 100 kg/h.
The sample A obtained in the step C-1 was immersed in an aqueous proteolytic enzyme solution (40° C.) for 30 seconds. The sample A was taken out from the aqueous proteolytic enzyme solution, and the sample A was immersed and washed in warm water (liquid temperature: 50° C.) for 120 seconds. Then, the sample A was drained with an air shower and allowed to be air-dried.
The aqueous proteolytic enzyme solution used was prepared according to the following procedure.
Triethanolamine and sulfuric acid were added to an aqueous solution of a proteolytic enzyme (BIOPRASE 30L, manufactured by Nagase ChemteX Corporation) (proteolytic enzyme concentration: 0.5% by mass), and the pH was adjusted to 8.5.
The sample A obtained in step D-1 was immersed in a 1% by mass glutaric acid aqueous solution (70° C.) for 2 minutes. The sample A was taken out from the aqueous glutaric acid solution, and the sample A was immersed and washed in water at 30° C. for 5 seconds. Glutaric acid manufactured by FUJIFILM Wako Pure Chemical Corporation was used.
The sample A obtained in the step G-1 was immersed in a plating liquid A (30° C.) having the following composition for 5 minutes. The sample A was taken out from the plating liquid A, and the sample A was immersed and washed in a 1% by mass citric acid buffer solution (pH=5, liquid temperature: 25° C.) for 30 seconds. That is, the neutralization and washing were carried out.
The composition of the plating liquid A (total volume: 1,200 ml) was as follows. The pH of the plating liquid A was 9.9, where the pH was adjusted by adding a predetermined amount of potassium carbonate (manufactured by FUJIFILM Wako Pure Chemical Corporation). In addition, the following components used were all manufactured by FUJIFILM Wako Pure Chemical Corporation. A change in line width before and after the plating treatment was not shown.
The sample A obtained in the step 2-1 was carried into a superheated steam treatment tank at 110° C. and allowed to stand for 30 seconds for the superheated steam treatment. The steam flow rate at this time was 100 kg/h.
In the sample A obtained in the step 4-1, the conductive thin wire formed a mesh pattern. The line width of the conductive thin wire was 1.8 μm, and the height of the conductive thin wire was 1.8 μm.
In addition, one hundred samples B in which a comb-tooth-shaped pattern for a migration test had been formed on a substrate were produced according to the same procedure as described above, except that the photomask used in the step (B-1) was changed. The pattern for the migration test was a pattern in accordance with IPC-TM650 or SM840, where the line width was 10 μm, the space width was 10 μm, the line length was 30 cm, and the number of lines was 17 or 18.
Each of a sample A having a mesh pattern formed from the conductive thin wire and a sample B having a comb-tooth-shaped pattern formed from the conductive thin wire was produced according to the procedure described in Example 1, except that as Examples 2 and 3 and Comparative Examples 1 to 4, each of plating liquids obtained by adjusting the adding amounts of the respective components such that the contents of potassium iodide and methyl hydroquinone as a reducing agent were the contents shown in Table 1 described later was used instead of the plating liquid A used in the step 2-1. The components of the immersion liquid used were all manufactured by FUJIFILM Wako Pure Chemical Corporation.
Regarding the conductive substrates obtained in each of Examples and Comparative Examples, the ratio I/Ag on the surface of the conductive thin wire was measured according to a method according to the above-described fluorescent X-ray analysis method.
The measurement results of the ratio I/Ag are shown in Table 1 which will be described later.
Hereinafter, a description will made for evaluation methods for the conductivity and the migration suppressing performance, which are evaluation items for the conductive substrate.
Regarding the obtained sample A of the conductive substrate, a line resistance value of the conductive mesh pattern region was measured. The line resistance value is a value obtained by dividing a resistance value measured by the four point probe method, by a distance between measurement terminals.
A measuring method for the line resistance value will be specifically described. First, after disconnecting both ends of any one conductive thin wire that constituted a mesh pattern included in the sample A, the conductive thin wire was cut and separated from the mesh pattern, four (A, B, C, and D) microprobes (tungsten probes (diameter: 0.5 μm), manufactured by Micro Support Co., Ltd.) were brought into contact with the cut and separated conductive thin wire, a constant current I was applied to the outermost probes A and D using a source meter (a 2400 type general-purpose source meter, a source meter manufactured by KEITHLEY Instruments) so that a voltage V between the internal probes B and C, which were separated apart by 250 μm, became 5 mV, and then a resistance value Ri=V/I was measured. The obtained resistance value Ri was divided by the distance between the B and C probes to determine a measured value, and an arithmetic average value of the measured values at any 10 positions was defined as a line resistance value. From the obtained line resistance value, the conductivity of each sample A was evaluated according to the following standards. In the evaluation of conductivity, among the following 1 to 5, 3 or more is preferable, 4 or more is more preferable, and 5 is still more preferable.
The sample B was allowed to stand in a moist and hot atmosphere at 60° C. and 90% RH, a wire was connected to both ends of the sample B, and a direct current of 5 V was continuously applied from one side. After each lapse of a certain period of time, the sample B was taken out from an atmosphere of 60° C. and 90% RH, and the insulating resistance of the sample B was measured using R8340A manufactured by Advantest Corporation.
The migration suppressing performance of the sample B was evaluated according to the following standards from the elapsed time from the start of the test and the measured value of the insulating resistance of the sample B.
In the table, the column of “CKI [mmol/L]” of “Plating treatment liquid” indicates the content of potassium iodide (unit: mmol/L) in the plating liquid, and the column of “CR [mmol/L]” indicates the content of the reducing agent (unit: mmol/L) in the plating liquid.
The column of “Ratio C” of “Plating treatment liquid” indicates a value calculated according to the expression of Ratio C=CKI/CR×1,000 in a case where the content of potassium iodide in the plating liquid is denoted as CKI mmol/L and the content of the reducing agent in the plating liquid is denoted as CR mmol/L.
The column of “Line width [μm]” of “Conductive thin wire” indicates the line width (unit: μm) of the conductive thin wire, and the column of “Height [μm]” indicates the height (unit: μm) of the conductive thin wire.
The column of “I/Ag” of “Conductive thin wire” indicates the ratio of the amount of iodine atoms to the amount of silver atoms on the surface of the conductive thin wire, which is measured by a fluorescent X-ray analysis.
As shown in Table 1 above, the conductive substrate according to the embodiment of the present invention exhibits a predetermined effect.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-159070 | Sep 2023 | JP | national |
