Structure having metal wiring and method for producing same

Abstract

To provide a structure with metal wiring with excellent linearity, and a manufacturing method thereof.SOLUTION: A structure includes a base material and metal wiring arranged on the base material, and there is a hole with an opening area of 0.3 μm2 or more and 700 μm2 or less on the surface of the metal wiring, and the area ratio of the hole with the opening area of 0.3 μm2 or more and 700 μm2 or less with respect to the surface area of the metal wiring is 0.5% or more and 70% or less, and there is also provided a manufacturing method of the structure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a structure having metal wiring and a method for manufacturing the same. [Background technology]

[0002] A circuit board has a structure in which conductive wiring is applied onto a substrate. The manufacturing method of a circuit board is generally as follows. First, a photoresist is applied onto a substrate to which a metal foil has been attached. Next, the photoresist is exposed to light and developed to obtain a negative shape of a desired circuit pattern. Next, the metal foil not covered by the photoresist is removed by chemical etching to form a pattern. This allows a high-performance conductive substrate to be manufactured.

[0003] However, the conventional methods have drawbacks such as the large number of steps, the complexity, and the need for a photoresist material.

[0004] In response to this, a direct wiring printing technique has been attracting attention, in which a dispersion (hereinafter also referred to as a "paste material") in which particles selected from the group consisting of metal particles and metal oxide particles are dispersed is used to directly print desired metal wiring on a substrate. This technique has a small number of steps, does not require the use of photoresist materials, and is therefore extremely productive.

[0005] One example of a direct printed wiring technique is a method in which a paste material is printed on a substrate by screen printing or inkjet printing, and then the paste material is thermally fired to obtain low-resistance metal wiring (see, for example, Patent Document 1).

[0006] Also, a method is known in which a paste material is applied to the entire surface of a substrate, and the paste material is selectively thermally fired by being irradiated with laser light in a pattern to obtain desired metal wiring (see, for example, Patent Documents 1 and 2).

[0007] Also, a method is known in which a dispersion liquid containing aggregate particles of cuprous oxide is applied to a polyethylene terephthalate (PET) substrate to a thickness of 10 to 20 μm, and then this is fired with laser light to produce copper wiring (see, for example, Patent Document 3). According to this method, areas other than the area irradiated with the laser light are not heated, so that a low heat-resistant resin material such as a PET substrate can be used as the substrate. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2010 / 024385 [Patent Document 2] Japanese Patent Application Publication No. 5-37126 [Patent Document 3] Special Publication No. 2010-534932 Summary of the Invention [Problem to be solved by the invention]

[0009] In the direct wiring printing technology described in Patent Documents 1 to 3, in which metal wiring is formed by irradiating a coating film of a paste material with a laser beam, the coating film may shrink during laser irradiation, or a substrate made of a low heat-resistant resin material may partially melt and penetrate the coating film, causing abnormalities such as cracks in the metal wiring. If such abnormalities occur at the ends of the metal wiring, the linearity of the metal wiring may deteriorate, narrowing the space between the metal wirings (see FIG. 1), which may cause migration to occur more easily. Furthermore, if abnormalities occur throughout the entire metal wiring, this may cause insulation of the metal wiring.

[0010] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a structure having metal wiring with excellent linearity, and a method for manufacturing the same. [Means for solving the problem]

[0011] That is, the present invention includes the following aspects. [1] A structure having a substrate and a metal wiring disposed on the substrate, The surface of the metal wiring is 2 More than 700μm 2 There are holes having an open area of The area of ​​the surface of the metal wiring is 2 More than 700μm 2 A structure in which the area ratio of holes having the following opening area is 0.5% or more and 70% or less. [2] The structure according to claim 1, wherein the metal wiring comprises copper and carbon. [3] 0.3 μm on the cross section of the thickness direction of the metal wiring 2 More than 700μm 2 3. The structure of any one of claims 1 to 2, wherein there is at least one hole having a cross-sectional area of: [4] The structure according to any one of the above aspects 1 to 3, which is a wiring material, an antenna for a housing of a portable information device, a mesh electrode, an electromagnetic wave shielding material, or a heat dissipation material. [5] A method for producing the structure according to any one of the above aspects 1 to 4, comprising the steps of: a coating step of applying a coating liquid containing a metal and / or a metal oxide onto a substrate to obtain a coating film; a laser light irradiation step of irradiating the coating film with a laser light to form metal wiring; A method for manufacturing a structure comprising: [6] The method for producing a structure according to aspect 5, wherein in the laser light irradiation step, the coating film is irradiated with the laser light in a state in which a gas is flowing above the coating film. [7] The method for producing a structure according to aspect 5 or 6, wherein the laser light has a central wavelength in the range of 355 nm or more and 550 nm or less. [8] The method for producing a structure according to any one of the above aspects 5 to 7, wherein in the laser light irradiation step, the laser light is repeatedly scanned onto the coating film while overlapping in a line width direction of the scanning line of the laser light. [9] The method for producing the structure according to the above aspect 8, wherein the overlap is 5% or more and 99.5% or less of the line width.

[10] The method for producing the structure according to any one of the above aspects 5 to 9, wherein the metal oxide is cuprous oxide. Effect of the Invention

[0012] According to one aspect of the present invention, it is possible to provide a structure having metal wiring with excellent linearity and a method for manufacturing the same. [Brief description of the drawings]

[0013] [Figure 1] 1 is an optical microscope photograph showing an example of an abnormal portion occurring at an end of a metal wiring. [Diagram 2] FIG. 1 is a schematic diagram of a structure according to one embodiment of the present invention. [Diagram 3] 1 is a scanning electron microscope (SEM) image of holes on a metal wiring surface in a structure according to one embodiment of the present invention. [Figure 4] 1A to 1C are schematic diagrams illustrating overlapping irradiation of laser light in a method for manufacturing a metal wiring according to one embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram of a metal wiring manufacturing apparatus used in one embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram illustrating a method for evaluating linearity in Example 1 and Comparative Example 1. [Figure 7] 3 is an optical microscope photograph of the surface of a metal wiring in Example 1. [Figure 8] 1 is an optical microscope photograph of a surface of a metal wiring in Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, one embodiment of the present invention (hereinafter, abbreviated as "this embodiment") will be described in detail.

[0015] <Structure> One aspect of the present invention provides a structure having a substrate and a metal wiring disposed on the substrate. 2 More than 700μm 2In one embodiment, the holes have an opening area of ​​0.3 μm 2 More than 700μm 2 The area ratio of holes having the following opening area is 0.5% or more and 70% or less.

[0016] Fig. 2 is a cross-sectional schematic diagram showing a structure according to this embodiment. Referring to Fig. 2, the structure 1 has a base material 11 and a metal wiring 13 arranged on a surface constituted by the base material 11. In a typical embodiment, the metal wiring 13 and an insulating region 14 are arranged adjacent to each other on the base material 11 in a cross-sectional view in the thickness direction to form a single layer 15. In one embodiment, the metal wiring 13 is a region of a coating film described later that is irradiated with laser light. In one embodiment, the insulating region 14 is a region of a coating film described later that is not irradiated with laser light, and may or may not be present.

[0017] [Base material] The base material 11 constitutes a surface on which the metal wiring 13 is disposed. There is no particular limitation on the shape. When the insulating region 14 is present, the material of the base material 11 is preferably an insulating material in order to ensure electrical insulation between the metal wirings 13 separated by the insulating region 14. However, it is not necessary that the entire base material 11 is made of an insulating material. It is sufficient that the portion constituting the surface on which the single layer 15 is disposed is made of an insulating material.

[0018] The surface of the base material on which the metal wiring is arranged may be a flat or curved surface, or may be a surface including steps. More specifically, the base material may be a substrate (e.g., a plate-like body, a film, or a sheet) or a three-dimensional object (e.g., a housing, etc.). The plate-like body is, for example, a support used in a circuit board such as a printed circuit board. The film or sheet is, for example, a base film that is a thin-film insulator used in a flexible printed circuit board.

[0019] Examples of the three-dimensional object include the housings of electrical devices such as mobile phone terminals, smartphones, smart glasses, televisions, personal computers, etc. Other examples of the three-dimensional object include dashboards, instrument panels, steering wheels, chassis, etc. in the automotive field.

[0020] Specific examples of the substrate include a substrate made of an inorganic material (hereinafter referred to as an "inorganic substrate") and a substrate made of a resin (hereinafter referred to as a "resin substrate").

[0021] The inorganic substrate is composed of, for example, glass, silicon, mica, sapphire, quartz, clay film, ceramic material, etc. The ceramic material is, for example, selected from alumina, silicon nitride, silicon carbide, zirconia, yttria, aluminum nitride, and a mixture of at least two of these. In addition, as the inorganic substrate, a substrate composed of glass, sapphire, quartz, etc., which have particularly high light transmittance, can be used.

[0022] Examples of the resin substrate include polypropylene (PE), polyimide (PI), polyester (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc.), polyethersulfone (PES), polycarbonate (PC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyacetal (POM), polyarylate (PAR), polyamide (PA) (PA6, PA66, etc.), polyamideimide (PAI), polyetherimide (PEI), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE), polyphenylene sulfide (PPS), polyetherketone (PEK), polyetheretherketone (PEEK), polyphthalamide (PPA), polyethernitrile (PENt), polybenzimidazole (PBI), polycarbodiimide, polymethacrylamide, nitrile rubber, acrylic rubber, polyethylene tetrafluoride, epoxy resin, etc. It is composed of oil, phenolic resin, melamine resin, urea resin, polymethylmethacrylate resin (PMMA), polybutene, polypentene, ethylene-propylene copolymer, ethylene-butene-diene copolymer, polybutadiene, polyisoprene, ethylene-propylene-diene copolymer, butyl rubber, polymethylpentene (PMP), polystyrene (PS), styrene-butadiene copolymer, polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), phenol novolac, benzocyclobutene, polyvinylphenol, polychloropyrene, polyoxymethylene, polysulfone (PSF), polyphenylsulfone resin (PPSU), cycloolefin polymer (COP), acrylonitrile-butadiene-styrene resin (ABS), acrylonitrile-styrene resin (AS), polytetrafluoroethylene resin (PTFE), polychlorotrifluoroethylene (PCTFE), and silicone resin (polysiloxane).

[0023] In addition to the above, a resin sheet containing cellulose nanofibers can also be used as the substrate.

[0024] In particular, at least one selected from the group consisting of PI, PET, and PEN is preferred because it has excellent adhesion to a single layer, is readily available in the market, and is available at low cost, which is advantageous from a business perspective.

[0025] Furthermore, at least one selected from the group consisting of PP, PA, ABS, PE, PC, POM, PBT, m-PPE, and PPS is preferable, particularly when used for a housing, because it has excellent adhesion to a single layer, excellent moldability and mechanical strength after molding, and heat resistance sufficient to withstand heat from laser light or the like irradiated when forming metal wiring.

[0026] The deflection temperature under load of the resin substrate is preferably 400°C or less, more preferably 280°C or less, and even more preferably 250°C or less. Substrates with a deflection temperature under load of 400°C or less are available at low cost and are advantageous from a business perspective, and are therefore preferred. From the viewpoint of the handleability of the resin substrate, the deflection temperature under load is preferably 70°C or more, or 80°C or more, or 90°C or more, or 100°C or more. The deflection temperature under load is a value measured in accordance with JIS K7191.

[0027] The thickness of the substrate, for example in the form of a plate, film or sheet, is preferably 1 μm to 100 mm, or 25 μm to 10 mm, or 25 μm to 250 μm. When the thickness of the substrate is 250 μm or less, the produced electronic device can be made lighter, more space-saving and more flexible, which is preferable.

[0028] When the substrate is a three-dimensional object, its maximum dimension (i.e., the maximum length of one side) is preferably 1 μm to 1000 mm, or 200 μm to 100 mm, or 200 μm to 5 mm. When a substrate having a thickness within the above range is used, the mechanical strength and heat resistance after molding are good.

[0029] Single Layer In this embodiment, the structure includes metal wiring 13, and typically has a single layer 15 including metal wiring 13 and insulating region 14. From the viewpoint of manufacturing using a simple process, it is preferable that both metal wiring 13 and insulating region 14 are present. On the other hand, from the viewpoint of improving insulation, it is preferable that insulating region 14 is not present.

[0030] In the single layer 15, "single" means that the layer is not a multilayer structure and that the layer is continuous in cross section. Therefore, the single layer is distinguished from a state in which the space between patterned wiring layers is filled with solder paste to form a single layer, as seen in a printed circuit board, for example. Also, "single" does not mean that the entire layer is homogeneous. In other words, the single layer may have differences in conductivity, particle state (fired and unfired), etc., such as the relationship between the metal wiring 13 and the insulating region 14, and a boundary (i.e., an interface) may exist between the metal wiring 13 and the insulating region 14.

[0031] (metal wiring) The metal wiring 13 exhibits electrical conductivity. In one embodiment, the metal wiring 13 is an irradiated region irradiated with laser light in a manufacturing method for obtaining a desired metal wiring by irradiating a laser light in a pattern and thermally sintering the same. In another embodiment, the metal wiring 13 is a sintered region including a sintered body obtained by sintering the insulating region 14 by light irradiation.

[0032] The shape of the metal wiring 13 in a plan view, i.e., the pattern, may be any shape such as a straight line, a curved line, a circle, a square, a bent shape, etc., and is not particularly limited. The pattern can be formed by scanning with a laser beam, so there are few restrictions on the shape.

[0033] The metal wiring includes metals such as copper and silver. Copper is preferred because of its low cost and high migration resistance. The copper in the metal wiring may have a structure in which copper-containing particles are fused to each other. In addition, the metal wiring may not have a particle shape and may be entirely fused, or a part of the metal wiring may have a particle shape and another part may be fused.

[0034] Furthermore, the metal wiring may contain a metal oxide, such as copper oxide (cuprous oxide, cupric oxide, and / or cuprous oxide), in addition to the metal. For example, the surface side portion of the metal wiring may have a structure in which copper-containing particles are fused together, and the substrate side portion may have a structure containing copper oxide. This is preferable because the copper oxide generates strong bonds between the copper particles and the copper oxide can further increase the adhesion between the copper particles and the substrate.

[0035] From the viewpoint of obtaining high conductivity, the content of metal elements in the metal wiring (in one embodiment, the copper content) is preferably 50 vol. % or more, 60 vol. % or more, or 70 vol. % or more, relative to 100 vol. % of the metal wiring, and may be 100 vol. %.

[0036] The metal wiring may contain the organic material. The content of the organic material in the metal wiring is preferably 0.5% by volume or more and 20% by volume or less with respect to 100% by volume of the metal wiring. When the content is 0.5% by volume or more, the bending resistance of the metal wiring is high, and when the content is 20% by volume or less, the metal wiring has low resistance and is suitable for practical use.

[0037] In one embodiment, the surface of the metal wiring has a thickness of 0.3 μm. 2 More than 700μm 2 In order to reduce the number of abnormalities that occur on the metal wiring, the opening area of ​​the hole is 0.3 μm in one embodiment. 2 More than 700μm 2 Less than or equal to 0.3 μm, preferably 2 More than 600μm 2 Less than or equal to 0.3 μm, more preferably 0.3 μm 2 More than 500μm 2 The following is the result.

[0038] In one embodiment, the ratio of the surface area of ​​the metal wiring to the surface area of ​​the metal wiring is 0.3 μm 2 More than 700μm 2 Percentage of holes with an opening area of ​​less than 0.3 μm 2 More than 600μm2 Percentage of holes with an opening area of ​​less than 0.3 μm 2 More than 500μm 2 The area ratio of holes having the following opening area is 0.5% or more and 70% or less. In one embodiment, the area ratio is 0.5% or more and 70% or less, preferably 1% or more and 50% or less, more preferably 1.5% or more and 30% or less, even more preferably 2% or more and 25% or less, even more preferably 2.5% or more and 20% or less, and even more preferably 3% or more and 20% or less, from the viewpoint of reducing abnormal parts occurring on the metal wiring.

[0039] 3 is a scanning electron microscope (SEM) image of holes on the surface of the metal wiring in the structure according to one embodiment of the present invention. When the coating film is irradiated with laser light, the volume of the coating film usually shrinks, but if the area ratio of the holes is within the above range, the stress caused by the volumetric shrinkage of the coating film due to the irradiation with laser light is alleviated, or the heat generated during the irradiation with laser light is dissipated to the outside of the coating film, so that abnormalities such as cracks in the metal wiring and partial scorching of the substrate are unlikely to occur (see FIG. 3).

[0040] The cross section of the metal wiring in the thickness direction is 0.3 μm 2 More than 700μm 2 It is preferable that there is at least one hole having a cross-sectional area of ​​0.3 μm or less. From the viewpoint of reducing abnormalities occurring on the metal wiring, the cross-sectional area of ​​the hole is preferably 0.3 μm or less. 2 More than 700μm 2 Less than or equal to 0.3 μm, more preferably 0.3 μm 2 More than 600μm 2 Less than 0.5 μm, more preferably 0.5 μm 2 More than 500μm 2 When holes are present in the cross-sectional direction of the metal wiring, the stress caused when the coating film shrinks in volume by irradiation with laser light is alleviated, or the heat generated during irradiation with laser light is dissipated to the outside of the coating film, so that abnormalities such as cracks in the metal wiring and partial scorching of the substrate are unlikely to occur.

[0041] The confirmation of the presence of holes having the above opening area or cross-sectional area and the calculation of the above area ratio are carried out using a scanning electron microscope (SEM) under the following conditions. Measurement device: Scanning electron microscope (e.g., FlexSEM1000, manufactured by Hitachi High-Technologies Corporation) Measurement conditions: Accelerating voltage 5 kV Measurement mode: Secondary electrons (for surface observation), or backscattered electrons (for cross-sectional observation) Observation magnification: 2000x (for surface observation) or 2500x (for cross-sectional observation) Field of view size for observation and image analysis: 40 μm × 40 μm (for surface observation), or a rectangle of [metal wiring thickness] × [length 40 μm in the direction perpendicular to the thickness direction] (for cross-sectional observation)

[0042] The area and area ratio of the holes are values ​​obtained by image analysis using the analysis software ImageJ (open source, public domain image processing software) from the image obtained by SEM observation. Specifically, the image is binarized (threshold value is 90 in one embodiment) so that the holes can be identified, the area ratio between the holes and the parts other than the holes is obtained, and the above-mentioned area ratio is calculated.

[0043] The size of the holes can be controlled by the scanning speed of the laser light and the spot diameter of the laser light during laser light irradiation. Increasing the laser light scanning speed tends to increase the size of the holes, while decreasing the laser light scanning speed tends to decrease the size of the holes. In addition, increasing the spot diameter tends to increase the size of the holes, while decreasing the spot diameter tends to decrease the size of the holes.

[0044] The above-mentioned area ratio of the holes on the surface of the metal wiring can be controlled by the scanning speed of the laser light during laser light irradiation and the overlap ratio described below when the laser light is irradiated in an overlapping manner as described below. Increasing the laser light scanning speed tends to increase the above-mentioned area ratio, while decreasing the laser light scanning speed tends to decrease the above-mentioned area ratio. Lowering the overlap ratio described below tends to increase the above-mentioned area ratio, while increasing the overlap ratio tends to decrease the above-mentioned area ratio.

[0045] The metal wiring preferably contains copper and carbon from the viewpoint of enhancing the sintering property of the metal particles during the laser light irradiation. The carbon may be graphene, carbon nanotubes, carbonized organic compounds, etc. In one embodiment, the carbon may be formed by carbonizing a part of a carbon precursor contained in the base material.

[0046] (Isolation area) The insulating region 14 exhibits electrical insulation. In one embodiment, the insulating region 14 is an unirradiated region that is not irradiated with laser light in a manufacturing method in which a desired metal wiring is obtained by irradiating a laser light in a pattern and thermally sintering the pattern. In one embodiment, the insulating region 14 is an unfired region that is not sintered by light irradiation.

[0047] In one embodiment, the insulating region contains a metal oxide, more specifically, copper oxide (cuprous oxide and / or cupric oxide in one embodiment). The copper oxide has, for example, a particulate shape. The average primary particle size of the particles containing copper oxide is preferably 1 nm or more and 100 nm or less, more preferably 1 nm or more and 50 nm or less, and even more preferably 1 nm or more and 20 nm or less. The smaller the particle size, the better the electrical insulation of the insulating region, and therefore, it is preferable. The average primary particle size is a value measured by a scanning electron microscope (SEM).

[0048] The insulating region may contain metal particles, such as copper particles, in addition to the metal oxide, i.e., the coating liquid described below may contain copper.

[0049] <Method of manufacturing the structure> One aspect of the present invention provides a method for producing a structure, the method comprising the steps of: a coating step of applying a coating liquid containing a metal and / or a metal oxide onto a substrate to obtain a coating film; a laser light irradiation step of irradiating the coating film with a laser light to form metal wiring; Includes. Hereinafter, a method using a coating liquid containing cuprous oxide particles will be described as an example, but the present invention is not limited thereto.

[0050] [Coating process] In this step, the coating liquid is applied onto the substrate to obtain a coating film. The coating liquid can be prepared by dispersing a metal and / or metal oxide in a dispersion medium. From the viewpoint of obtaining low-resistance metal wiring, copper particles are preferred as the metal. From the viewpoint of the stability of the coating liquid, copper oxide particles are preferred as the metal oxide, and cuprous oxide particles are particularly preferred as the copper oxide particles. In a preferred embodiment, the coating liquid contains copper oxide particles and a dispersant. The dispersant is preferably a phosphorus-containing organic compound, but other dispersants may be used as long as they do not adversely affect the electrical insulation of the insulating region.

[0051] For example, the coating liquid is applied onto a substrate, and the dispersion medium is removed by drying as necessary to form a coating film. The method for forming the coating film is not particularly limited, and coating methods such as die coating, spin coating, slit coating, bar coating, knife coating, spray coating, and dip coating can be used. It is desirable to apply the coating liquid to a uniform thickness on the substrate using these methods.

[0052] The dispersion medium in the coating liquid may be removed by drying. The drying conditions and drying state may be set arbitrarily. The drying conditions may be, for example, 60° C. to 120° C. for 30 minutes to 5 hours. In this manner, a coating film can be formed.

[0053] [Laser light irradiation process] In this process, the coating film is irradiated with a laser beam to form metal wiring. In one embodiment, the coating film is selectively irradiated with the laser (i.e., only the portion where the metal wiring is to be formed). For example, in a coating film containing metal oxide particles, reduction of the metal oxide and sintering of the particles proceed only in the portion of the coating film irradiated with the laser beam, and metal particles are generated and fused (i.e., integrated) by sintering the generated metal particles to each other, forming metal wiring.

[0054] Since the coating film usually contains organic components such as a solvent and a dispersant, the coating film may generate smoke due to heating by the laser light during laser light irradiation. If the smoke enters the irradiation optical path of the laser light and blocks the laser light, the laser light is scattered. In this embodiment, it is preferable to perform the laser light irradiation in a state where a gas is flowing on the coating film in order to suppress scattering of the laser light. The gas used in this case is not particularly limited, but may include air, nitrogen, argon, helium, etc., and nitrogen is preferable in terms of being inert and inexpensive.

[0055] In addition, the gas flow does not need to occur at the same flow rate over the entire coating film, but only needs to occur at the point on the coating film where the laser light is irradiated. From the viewpoint of obtaining the effect of the present invention, it is preferable that the gas flow occurs in an area with a radius of 10 mm from the point on the coating film where the laser light is irradiated. In this case, it is not necessary for the gas flow to occur at the same level over the entire area, but it is preferable that the gas flow occurs over the area with a flow rate in the range of 0.01 m / s to 1.0 m / s, or 0.05 m / s to 0.8 m / s, or 0.1 m / s to 0.6 m / s. When the flow rate is 0.01 m / s or more, the smoke removal effect is good, and when it is 1.0 m / s or less, the gas blown in the device is unlikely to cause turbulence, so that the smoke can be prevented from entering the optical path of the laser light. In the present disclosure, the value measured by installing a measuring part of an anemometer at a position 10 mm away from the laser light irradiation point on the coating film surface in the perpendicular direction to the coating film is defined as the flow rate of the gas on the coating film.

[0056] The means for generating the gas flow is not particularly limited as long as it can cause the gas to flow onto the coating film, and any blower can be used. The blower may be, for example, a type that blows air by motor drive, a type that is configured to directly flow gas from a high-pressure gas cylinder through a pipe, or a device that flows gas compressed by a compressor or the like.

[0057] (Overlapping irradiation of laser light) The laser light may be repeatedly applied to a desired area on the coating film. FIG. 4 is a schematic diagram illustrating overlapping irradiation of the laser light in a method for producing metal wiring according to one embodiment of the present invention. Referring to FIG. 4, after irradiating the laser light as a first scanning line R1 having a scanning line width S1, the laser light is irradiated as a second scanning line R2 so as to overlap the first scanning line R1 in the scanning line width direction. Such overlapping can increase the sintering degree of the coating film, and can form a hard metal wiring. As a result, for example, when the metal wiring is formed on a flexible substrate and bent, the metal wiring can be made to follow the flexible substrate without cracking.

[0058] The ratio S2 / S1 of the overlap width S2 to the scan line width S1 of the first scan line R1 (also referred to as overlap ratio S in the present disclosure) is preferably 5% to 99.5%, or 10% to 99%, or 20% to 95%, or 30% to 90%, or 40% to 85%. When the overlap ratio is 5% or more, sintering of the metal and / or metal oxide proceeds well, and when it is 99.5% or less, wiring can be manufactured at a practical production speed. The scanning direction of the second scan line may be the same as or different from that of the first scan line.

[0059] (laser light emission wavelength) The emission wavelength of the laser light preferably has a central wavelength in the range of 355 nm to 550 nm. When the coating film contains metal particles such as copper, silver, gold, and aluminum, the metal particles can be effectively sintered by irradiating the coating film with a laser light having a wavelength in this range. From the viewpoint of enhancing the sinterability of the metal particles, the laser light preferably has a central wavelength in the range of 355 nm to 400 nm, more preferably 355 nm.

[0060] (laser light incident angle) The incident angle of the laser light to the coating film is preferably 0 to 50 degrees, or 0 to 48 degrees, or 0 to 45 degrees. When the incident angle is 50 degrees or less, insufficient sintering of the coating film caused by the laser light being reflected on the surface of the coating film or the amount of light rays penetrating into the coating film is small can be prevented, and the resistance value of the metal wiring can be made low and uniform.

[0061] <Metal wiring manufacturing equipment> The structure of this embodiment can be manufactured, for example, by using a metal wiring manufacturing apparatus as described below. Fig. 5 is a schematic diagram of a metal wiring manufacturing apparatus used in one embodiment of the present invention. Referring to Fig. 5, the metal wiring manufacturing apparatus 10 includes a structure holding unit 101 and a light beam oscillator 102. In one embodiment, the metal wiring manufacturing apparatus 10 may include an inert gas generator 103, a light beam scanning unit 104, a speed control unit 105, and / or a computer 106.

[0062] [Structure holding part] In one embodiment, the structure holder 101 is a sample chamber. The sample chamber may have a window. The window has light transmittance that allows light to reach the coating film 12 through the window. In one embodiment, the light transmittance of the window at a wavelength of 532 nm may be 80% or more, and preferably 85% or more, or 90% or more. The light transmittance is ideally 100%, but may be, for example, 98% or less, or 95% or less, from the viewpoint of ease of forming the window. The light transmittance is a value measured by an ultraviolet-visible spectrophotometer.

[0063] The sample chamber may have an inert gas inlet, and may be configured, for example, so that an inert gas generated by an inert gas generator 103 is introduced into the sample chamber via the inert gas inlet.

[0064] [Inert gas generator] The inert gas generator 103 generates an inert gas to be supplied to the structure holding part 101. For example, when the inert gas generator 103 is a nitrogen gas generator, it can separate and purify nitrogen from air and supply the nitrogen to the inside of the structure holding part 101. By providing the metal wiring manufacturing apparatus 10 with the inert gas generator 103, a cylinder or the like is not required, and space saving and cost reduction can be achieved.

[0065] The inert gas generator 103 may be, for example, an adsorption type or a membrane type. For example, in an adsorption type nitrogen gas generator, the purity of the nitrogen gas can be increased by utilizing the difference in adsorption speed when nitrogen and oxygen in the air are adsorbed by an adsorbent. On the other hand, in a membrane type nitrogen gas generator, compressed air is supplied to a pressure vessel containing a hollow fiber membrane made of a polymer material, and oxygen gas is allowed to pass through and removed, thereby obtaining high-purity nitrogen gas.

[0066] [Light Oscillator] The light beam oscillator 102 is configured to emit a light beam at a desired wavelength. In a typical embodiment, the light beam is a laser beam. When using a laser beam as the light beam, a laser light source such as YAG (yttrium aluminum garnet), YVO (yttrium vanadate), Yb (ytterbium), a semiconductor (GaAs, GaAlAs, GaInAs), or carbon dioxide gas may be used. The laser beam may be not only a fundamental wave but also a harmonic wave extracted as necessary. Also, an LED light may be used as the light beam. The light beam oscillator 102 may be equipped with a cooling device or the like.

[0067] [Light scanning unit] The light beam scanning unit 104 scans the light beam L emitted from the light beam oscillator 102. FIG. 5 shows an example in which the light beam scanning unit 104 is a galvanometer scanner. The galvanometer scanner as the light beam scanning unit 104 has an X-axis galvanometer mirror 104a, an X-axis galvanometer motor 104b, a Y-axis galvanometer mirror 104c, and a Y-axis galvanometer motor 104d. The galvanometer scanner may have an fθ lens (not shown), a Z-axis adjustment drive lens (not shown), and the like. The X-axis galvanometer motor 104b and the Y-axis galvanometer motor 104d are electrically connected to a speed control unit 105 (e.g., a scanner control unit).

[0068] The galvano scanner is configured to be able to control the rotation angle and rotation speed of the X-axis galvano motor 104b and the Y-axis galvano motor 104d in accordance with a control signal from a speed control unit 105. The speed control unit 105 is controlled by a computer . The light beam L is scanned by the light beam scanning unit 104 and irradiated onto the surface of the coating film 12 formed on the substrate 11 .

[0069] In the above, a galvano scanner is exemplified as the light beam scanning unit 104, but a light beam scanning unit other than a galvano scanner can also be used. For example, instead of the galvano scanner, the light beam scanning unit 104 may use an XY stage as a mounting table that can move the substrate 11 on which the coating film 12 is formed in both the X-axis direction and the Y-axis direction, and move the substrate 11 instead of moving the irradiation point P of the laser light L.

[0070] The light beam scanning unit 104 (galvanometer scanner) shown in FIG. 5 uses an X-axis galvanometer mirror 104a and a Y-axis galvanometer mirror 104c for movement in the X-axis and Y-axis directions, respectively. However, it is also possible to use a galvanometer mirror for either the X-axis or the Y-axis, for example, to use a galvanometer mirror for movement only in the X-axis direction and a motor of a mounting table (not shown) on which the substrate 11 is placed, for movement in the Y-axis direction.

[0071] The scanning speed control in the metal wiring manufacturing apparatus 10 can be performed, for example, as follows. First, scanning data (coordinate data) indicating the desired shape, position, and size of the metal wiring pattern is input to the speed control unit 105. The scanner control unit as the speed control unit 105 calculates the length (L) (unit: mm) of the scanning line from the length along the X-axis direction of the pattern based on the scanning data. Next, based on the calculated scanning line length (L), the scanner control unit calculates the speed (V) (unit: mm / sec) at which the laser light is scanned (hereinafter referred to as scanning speed) so as to obtain a predetermined scanning period (F) (unit: Hz) (e.g., 15 Hz) using the following formula. Scanning speed (V) = Scanning period (F) x Scan line length (L)

[0072] Next, the scanner control unit causes the galvano scanner serving as the light beam scanning unit 104 to move the irradiation point P of the laser light L in the X-axis direction according to the scanning speed calculated in this manner, and executes one scan. Thereafter, the scanner control unit causes the galvano scanner to move the irradiation point P of the laser light L in the Y-axis direction. As described above, the scanning speed (V) of the laser light L can be set based on the length (L) of the scan line so that the scanning period (F) is the same at any position within the coating film 12.

[0073] [Output adjustment mechanism] The metal wiring manufacturing apparatus may include an output adjustment mechanism for adjusting the output of the light beam. This makes it possible to suppress ablation and / or carbonization during irradiation of the light beam. One example of the output adjustment mechanism is an attenuator disposed on the path of the light beam. The attenuator is electrically connected to a computer and can change the output value to an arbitrary value in response to a control signal from the computer. Alternatively, the output adjustment mechanism may be configured so that the output value can be changed by manual operation.

[0074] [Pulse suppression mechanism] When the light oscillator is configured to emit pulsed light, the metal wiring manufacturing apparatus may include a pulse suppression mechanism that suppresses the initial pulse of the pulsed light. The pulse suppression mechanism prevents ablation and / or carbonization by preventing an excessively large pulse of light at the start of emission from being irradiated onto the coating film. The pulse suppression mechanism may have, for example, a first pulse suppression function (FPS function), that is, a function of predicting excess output of the initial pulse in advance and reducing the excess output.

[0075] [Spot adjustment mechanism] The metal wiring manufacturing apparatus may have a spot adjustment mechanism that adjusts the spot diameter at the focal position of the light beam. The spot adjustment mechanism prevents ablation and / or carbonization by controlling the condensing density of the light beam to adjust the spot diameter. One example of the spot adjustment mechanism is a device that expands or reduces the diameter of the light beam incident on the galvano scanner, and for example, a beam expander can be used. By changing the diameter of the light beam, the spot diameter at the focal point focused by the focusing lens can be changed. By expanding the diameter of the light beam, the spot diameter becomes smaller, and by reducing the diameter of the light beam, the spot diameter becomes larger.

[0076] <Application Examples> The structure according to the present embodiment can be suitably applied to, for example, wiring materials for electronic circuit boards and the like (printed circuit boards, RFID, replacement for wire harnesses in automobiles, etc.), antennas (antennas for portable information device housings) formed on the housings of portable information devices (smartphones, etc.), mesh electrodes (electrode films for capacitive touch panels), electromagnetic wave shielding materials, and heat dissipation materials. EXAMPLES

[0077] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0078] [Example 1] <Preparation of Dispersion> 80 g of copper(II) acetate monohydrate (Wako Pure Chemical Industries, Ltd.) was dissolved in a mixed solvent consisting of 800 g of ion-exchanged water and 400 g of 1,2-propylene glycol (Wako Pure Chemical Industries, Ltd.), 20 g of hydrazine hydrate (Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred under a nitrogen atmosphere, and then separated into a supernatant and a precipitate by centrifugation.

[0079] To the resulting precipitate (2.8 g), 0.4 g of DISPERBYK-145 (trade name, manufactured by BYK-Chemie) (BYK-145) as a phosphorus-containing organic compound and 6.6 g of ethanol (manufactured by Wako Pure Chemical Industries) as a dispersion medium were added, and the mixture was dispersed under a nitrogen atmosphere using a homogenizer, followed by centrifugation to recover the precipitate. The precipitate was diluted with ethanol and dispersed using a homogenizer. By repeating the above-mentioned centrifugation (concentration) and dispersion (dilution), a dispersion containing cuprous oxide particles containing cuprous oxide (copper(I) oxide) was obtained. The final composition was 2.8 g of precipitate, 0.4 g of BYK145, 6.6 g of ethanol, and 0.01 g of hydrazine hydrate.

[0080] <Sample preparation> The surface of a polyimide substrate measuring 70 mm x 70 mm x 0.1 mm in width x depth x thickness was subjected to UV ozone treatment for 3 minutes, after which 1 ml of the dispersion was dropped onto the substrate and spin-coated (500 rpm x 300 seconds), dried at room temperature for 10 minutes, and then dried at 90°C for 2 hours to obtain a sample in which a coating film having a thickness of 3.5 μm was formed on the substrate.

[0081] <Laser-based baking and electrical conductivity evaluation> A metal wiring manufacturing apparatus 10 having the configuration shown in FIG. 5 was used. Nitrogen gas was fed into the sample chamber at 1.0 L / min. The upper surface of the sample chamber was made of glass, and had a structure that allowed the laser light to pass through. Using a galvano scanner (as the light beam scanning unit 104), the coating film in the sample chamber was irradiated with laser light (center wavelength 355 nm, frequency 300 kHz, pulse output 920 mW, spot diameter 150 μm) while moving the focal position at a maximum speed of 100 mm / sec. At this time, the laser light was moved 5 mm in the scanning direction (first irradiation), and then moved 10 μm in a direction perpendicular to the scanning direction and moved again in the scanning direction at a maximum speed of 100 mm / sec (second irradiation). By repeating this operation, the laser light was scanned while moving 10 μm at a time in a direction perpendicular to the scanning direction, and a metal wiring containing copper having the desired dimensions of 5 mm in length x 1 mm in width was obtained.

[0082] <Calculating the overlap rate> When the surface of the obtained metal wiring was observed with an optical microscope (magnification 20 times), the scanning lines of the laser light were confirmed to be spaced 22 μm apart. In addition, the width of the trajectory of the laser light irradiation in the non-overlapping part at the scanning end of the metal wiring was 255 μm. The overlap rate was calculated using the following formula and was found to be 88.5%. (Overlap ratio) = (191 μm - 22 μm) ÷ 191 μm

[0083] <Evaluation of holes in metal wiring> 0.3μm on metal wiring 2 More than 700μm 2 The area ratio of holes with the following opening areas was measured by image analysis of images obtained by scanning electron microscope (SEM). The opening area of ​​holes on the metal wiring surface is 0.3 μm 2 ~136μm 2 and 0.3 μm 2 More than 700μm 2 The area ratio of holes with an opening area of ​​0.01 μm or less was 15.9%. 2 ~1.9μm 2 There were holes. The measurement conditions for SEM are as follows. Measurement equipment: Hitachi High-Technologies Corporation Scanning Electron Microscope FlexSEM1000 Measurement conditions: Accelerating voltage 5 kV Measurement mode: Secondary electrons (for surface observation), or backscattered electrons (for cross-sectional observation) Observation magnification: 2000x (for surface observation) or 2500x (for cross-sectional observation)

[0084] The area and area ratio of the holes were determined from the images obtained by SEM observation by image analysis using the analysis software ImageJ. The range for image analysis was a rectangle of 40 μm × 40 μm on the surface of the metal wiring, and [metal wiring thickness] × [length 40 μm in the direction perpendicular to the thickness direction] on the cross section. Next, the image of the field of view set above was binarized so that the holes could be identified. The circularity of the analysis target was set to 0 to 1. Holes in contact with the outer frame of the rectangle were also included in the area of ​​the holes. The threshold for binarization was set to 90. Furthermore, scanning electron microscope observation-energy dispersive X-ray analysis (SEM-EDX) revealed that the metal wiring contained copper and carbon. The measurement conditions for SEM-EDX are as follows. Measurement equipment: Hitachi High-Technologies Corporation Scanning Electron Microscope FlexSEM1000 Measurement conditions: Acceleration voltage 15 kV Analysis method: Spectral analysis of selected metal wiring

[0085] <Evaluation of Linearity> The linearity was evaluated by observation with an optical microscope. As shown in Figure 6, the ends of the metal wiring were connected by a straight line, and if there was no protruding part from the straight line (part indicated by an arrow in Figure 6) or if there was a protruding part, it was less than 10 μm, it was evaluated as passing, and if the protruding part was 10 μm or more, it was evaluated as failing. The observation with the optical microscope was performed at a magnification of 5 times, and 10 points on the metal wiring part were observed. If the evaluation of all 10 points was passing, the linearity evaluation was evaluated as passing, and if the evaluation of one or more points was failing, the linearity evaluation was evaluated as failing. Fig. 7 shows an optical microscope image of the metal wiring obtained in Example 1. In the image shown in Fig. 7, no abnormal parts were found at the ends of the metal wiring (see the boxed area in Fig. 7), and the linearity evaluation was acceptable.

[0086] [Comparative Example 1] Metal wiring was formed and evaluated in the same manner as in Example 1, except that the scanning speed of the focal position of the laser light was 5 mm / sec, the output was 500 mW, the spot diameter was 110 μm, and the overlap rate was 91.1%. The metal wiring surface has an opening area of ​​0.005 μm 2 ~0.05μm 2 While there were pores of 0.05 μm 2 There were no holes with an opening area exceeding 0.3 μm. 2 More than 700μm 2 The area ratio of holes with an opening area of ​​0.01 μm or less was 0%. 2 ~0.15μm 2 While there were pores of 0.15 μm 2 There were no holes with a cross-sectional area exceeding . Scanning electron microscope observation-energy dispersive X-ray analysis (SEM-EDX) revealed that the metal wiring contained copper and carbon. Fig. 8 shows an optical microscope image of the metal wiring obtained in Comparative Example 1. As shown in Fig. 8, in Comparative Example 1, an abnormal part was found at the end of the metal wiring (see the part surrounded by a box in Fig. 8), and the linearity evaluation was failed.

[0087] From the results of Example 1 and Comparative Example 1, it was found that when the metal wiring contains holes at a predetermined ratio, as in Example 1, it is possible to form metal wiring with high linearity. [Industrial Applicability]

[0088] The highly linear metal wiring obtained by the present invention can be suitably used as wiring materials for electronic circuit boards, mesh electrodes, electromagnetic wave shielding materials, heat dissipation materials, and the like. [Explanation of symbols]

[0089] 1 structure 10 Metal wiring manufacturing equipment 11 Base material 12 Coating 13 Metal wiring 14 Insulation Area 15 Single Layer 101 Structure holding part 102 Light Oscillator 103 Inert Gas Generator 104 Light beam scanning unit 104a X-axis galvanometer mirror 104b X-axis galvanometer motor 104c Y-axis galvanometer mirror 104d Y-axis galvanometer motor 105 Speed ​​control section 106 Computer L Laser light R1 1st scan line R2 Second scan line S1 Scan line width S2 overlap width

Claims

1. A structure having a substrate and a metal wiring disposed on the substrate, The surface of the metal wiring is 2 700 μm or more 2 There are holes having an open area of The 0.3 μm 2 700 μm or more 2 The area ratio of holes having the following opening area is 0.5% or more and 70% or less, The structure, wherein the metal wiring comprises copper and carbon.

2. A structure having a substrate and a metal wiring disposed on the substrate, The surface of the metal wiring is 2 700 μm or more 2 There are holes having an open area of The 0.3 μm 2 700 μm or more 2 The area ratio of holes having the following opening area is 0.5% or more and 70% or less, A structure in which at least one hole having a cross-sectional area of ​​0.3 μm 2 or more and 700 μm 2 or less is present in a cross section in the thickness direction of the metal wiring.

3. The structure of claim 2 , wherein the metal interconnect comprises copper and carbon.

4. The structure according to any one of claims 1 to 3, which is a wiring material, an antenna for a portable information device housing, a mesh electrode, an electromagnetic wave shielding material, or a heat dissipation material.

5. A method for producing the structure according to any one of claims 1 to 4, comprising the steps of: A coating step of applying a coating liquid containing a metal and / or a metal oxide onto a substrate to obtain a coating film; a laser light irradiation step of irradiating the coating film with a laser light to form metal wiring; A method for manufacturing a structure comprising:

6. A method for manufacturing a structure having a substrate and metal wiring disposed on the substrate, comprising: a hole having an opening area of ​​0.3 μm or more and 700 μm or less is present on a surface of the metal wiring, the area ratio of the holes having an opening area of ​​0.3 μm 2 or more and 700 μm 2 or less to the area of ​​the surface of the metal wiring is 0.5% or more and 70% or less, The method further comprising: A coating step of applying a coating liquid containing a metal and / or a metal oxide onto a substrate to obtain a coating film; a laser light irradiation step of irradiating the coating film with a laser light to form metal wiring; A method for manufacturing a structure comprising:

7. The method for producing a structure according to claim 5 or 6, wherein in the laser light irradiation step, the coating film is irradiated with the laser light in a state in which a gas is flowing over the coating film.

8. The method for manufacturing a structure according to any one of claims 5 to 7, wherein the laser light has a central wavelength in the range of 355 nm or more and 550 nm or less.

9. The method for producing a structure according to any one of claims 5 to 8, wherein in the laser light irradiation step, the laser light is repeatedly scanned onto the coating film while overlapping in a line width direction of a scanning line of the laser light.

10. The method for manufacturing a structure according to claim 9 , wherein the overlap is from 5% to 99.5% of the line width.

11. The method for producing a structure according to any one of claims 5 to 10, wherein the metal oxide is cuprous oxide.

Images