Flexible transparent wiring substrate and method for manufacturing flexible transparent wiring substrate

Abstract

To provide a flexible transparent wiring substrate with a structure capable of achieving good transparency, elasticity and bending resistance of the flexible transparent wiring substrate, and a method for manufacturing the flexible transparent wiring substrate.SOLUTION: A flexible transparent wiring substrate 100 has a base substrate 10 that is flexible, transparent, and insulating and has grooves 20 patterned on its top surface, and a wiring pattern 30 formed by wiring component material 32 filled in the grooves 20, and the grooves 20 are formed in a V-shape with a narrow width in a depth direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flexible transparent wiring board and a method for manufacturing a flexible transparent wiring board. [Background technology]

[0002] The flexible transparent wiring substrate described in Patent Documents 1 and 2 comprises a base material having a pattern of grooves formed on its upper surface, and a wiring pattern formed by a wiring material filled in the grooves, and the grooves have a substantially constant width regardless of their position in the depth direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-528502 [Patent Document 2] JP 2006-120888 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the investigations of the present inventors, the flexible transparent wiring boards described in Patent Documents 1 and 2 have room for improvement in terms of realizing good transparency, stretchability, and bending resistance of the flexible transparent wiring board.

[0005] The present invention has been made in consideration of the above problems, and relates to a flexible transparent wiring board having a structure capable of realizing good transparency, stretchability, and bending resistance of the flexible transparent wiring board, and a method for manufacturing the flexible transparent wiring board. [Means for solving the problem]

[0006] According to the present invention, a flexible, transparent, and insulating base material having a groove pattern formed on an upper surface thereof; a wiring pattern formed by filling the groove with a wiring material; and Equipped with The groove is formed in a narrow V-shape in the depth direction of the flexible transparent wiring substrate.

[0007] According to the present invention, a method for manufacturing a laminated body includes the steps of: preparing a laminated body including a flexible, transparent, and insulating base material and a protective layer removably attached to an upper surface of the base material; forming a pattern of grooves in the base substrate by irradiating the base substrate with laser light through the protective layer of the laminate; filling the grooves with a wiring material and drying it to form a wiring pattern; peeling the protective layer from the base substrate; Equipped with In the step of patterning the groove, the groove is formed in a narrow V-shape in the depth direction, in a method for producing a flexible transparent wiring substrate. Effect of the Invention

[0008] According to the present invention, it is possible to realize a flexible transparent wiring substrate having good transparency, stretchability and bending resistance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional end view of the flexible transparent wiring substrate, showing a cross section perpendicular to the extending direction of the wiring pattern. [Diagram 2] FIG. 2 is a schematic plan view of a flexible transparent wiring substrate. [Diagram 3] Figures 3(a) and 3(b) are enlarged partial views of part A shown in Figure 1, where Figure 3(a) shows the state in which the upper surface of the wiring material is concave toward the center in the width direction, and Figure 3(b) shows the state in which the height position of the upper surface of the wiring material is lower than the height position of the groove opening. [Figure 4]4(a) and 4(b) are partially enlarged views of the wiring pattern, of which FIG. 4(a) is a cross-sectional view perpendicular to the extension direction of the wiring pattern, and FIG. 4(b) is a side view of the wiring pattern as viewed in the direction of arrow A shown in FIG. 4(a). [Diagram 5] Figures 5(a), 5(b) and 5(c) are cross-sectional end views for explaining a manufacturing method of a flexible transparent wiring substrate, in which Figure 5(a) shows the step of preparing a laminate, Figure 5(b) shows the step of patterning a groove, and Figure 5(c) shows the step of forming a wiring pattern. [Figure 6] Figures 6(a) and 6(b) are cross-sectional end views for explaining a manufacturing method of a flexible transparent wiring substrate, in which Figure 6(a) shows the step of peeling off the protective layer, and Figure 6(b) shows the step of attaching an insulating cover to a base substrate. [Figure 7] FIG. 2 is a partially enlarged view of a cut end surface of a flexible transparent wiring substrate, showing an example in which a groove is formed in a narrow U-shape in the depth direction. [Figure 8] 8(a), 8(b) and 8(c) are cross-sectional views for explaining a method for producing a flexible transparent wiring substrate, and show a process for forming a groove having a width narrower than the diameter of the laser light. [Figure 9] 9(a), 9(b), and 9(c) are cross-sectional views for explaining a method for manufacturing a flexible transparent wiring substrate, and show a process for forming a groove having a width greater than the diameter of the laser light. [Figure 10] Figures 10(a), 10(b), 10(c) and 10(d) are images of a cross section of a flexible transparent wiring substrate during the process of patterning a groove, showing the process in which a laser-processed groove is formed in the laminate by irradiating laser light. [Figure 11] FIG. 13 is a photographed image of a cross section of a flexible transparent wiring substrate, showing a state in which the upper surface of the wiring material is a concave surface recessed toward the center in the width direction. [Figure 12] FIG. 2 is a photographed image of a cross section of a flexible transparent wiring substrate, showing a state in which a carbon layer is formed on a wiring constituent material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the following, when describing the positional relationship between the components of the flexible transparent wiring substrate 100, the upper side in Fig. 1 will be referred to as the upper side or upper side, and the opposite side will be referred to as the lower side or lower side, etc. However, these directional definitions are for convenience only and do not limit the directions during manufacture or use of the flexible transparent wiring substrate 100.

[0011] As shown in Figures 1 to 3(b), the flexible transparent wiring substrate 100 of this embodiment comprises a flexible, transparent, and insulating base substrate 10 having grooves 20 patterned on an upper surface 10a, and a wiring pattern 30 formed by a wiring material 32 filled in the grooves 20. The groove 20 is formed in a V-shape that narrows in the depth direction. The term "transparent" used here means transparent to visible light. Moreover, the "top surface of the base substrate 10" here means, of the main surfaces on the front and back sides of the base substrate 10, the surface on the side where a portion of the wiring pattern 30 is exposed from the base substrate 10. However, the definition of the "top surface" here is for convenience, and does not limit the direction during manufacturing or use of the flexible transparent wiring substrate 100. Moreover, the term "V-shape" as used herein includes, for example, a U-shape as shown in FIG.

[0012] According to this embodiment, the groove 20 is formed in a narrow V-shape in the depth direction. Therefore, even if the groove 20 is set to a narrow width, when the wiring material 32 is filled into the groove 20, the wiring material 32 can be smoothly flowed into the entire inside of the groove 20 by capillary action. Therefore, a narrow wiring pattern 30 can be easily formed. As a result, the formation area of ​​the wiring pattern 30 on the base substrate 10 can be kept to a minimum, so that the transparency, stretchability, and bending resistance of the base substrate 10 can be suppressed from being impaired. That is, according to this embodiment, the flexible transparent wiring substrate 100 can achieve good transparency, stretchability, and bending resistance.

[0013] The flexible transparent wiring substrate 100 according to this embodiment is used as a wiring substrate for, for example, vehicle-mounted glass-attached antennas, glass-attached sensors, switches, wearable devices, touch panels, and the like. As an example, the flexible transparent wiring substrate 100 is attached to an object to be attached. In this case, the flexible transparent wiring substrate 100 expands and contracts and curves in accordance with the unevenness and deformation of the object to be attached.

[0014] The base material 10 is, for example, a relatively thin film-like material having front and back principal surfaces. The base substrate 10 is made of a transparent resin material having insulating properties and flexibility, and in this embodiment, is made of polyethylene terephthalate (PET). However, the material of the base substrate 10 is not limited to this example, and may be, for example, polyimide (PI), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), fluorine-based resin (PolyTetra FluoroEthylene: PTFE), or a resin material containing these.

[0015] 1, a wiring pattern 30 is formed on the upper surface 10a of the base substrate 10. The wiring pattern 30 is electrically connected to, for example, an external device (not shown) mounted on the base substrate 10, thereby forming a circuit. The external device is not particularly limited, but examples thereof include a semiconductor chip, a ceramic capacitor, a resistor, and the like. As described above, the wiring pattern 30 is formed by filling the grooves 20 of the base substrate 10 with the wiring material 32. More specifically, the wiring pattern 30 is a coating film formed by the wiring material 32. As shown in Fig. 1 and Fig. 4(a), in a cross section perpendicular to the extension direction of the wiring pattern 30 (for example, a cross section along line AA shown in Fig. 2), the wiring pattern 30 is also formed in a narrow V-shape in the depth direction, similar to the grooves 20. In addition, in FIG. 4(a) and FIG. 4(b), only the wiring pattern 30 is selectively illustrated, and the base material 10 and an insulating cover 50 described later are omitted from the illustration.

[0016] The wiring constituent material 32 has high flexibility and can follow the bending deformation of the base material 10 . This allows the wiring pattern 30 formed by the wiring structuring material 32 to smoothly follow the bending deformation of the base material 10. This allows the flexible transparent wiring board 100 to have better stretchability and bending resistance.

[0017] In the present embodiment, for example, the wiring material 32 is a conductive paste, and is a coating film formed by hardening it through a heat treatment (for example, a drying process described later). However, in the present invention, the wiring material 32 may be, for example, a conductive nano-ink. More specifically, the wiring material 32 (conductive paste) is configured to include, for example, conductive particles and a binder resin. The wiring material 32 may further include, for example, a surfactant. When the wiring material 32 is a conductive nano-ink, the wiring material 32 (conductive nano-ink) is configured to include, for example, conductive particles, a solvent, and a dispersant. The conductive particles are, for example, metal particles 32a of silver, gold or copper. Examples of the binder resin include epoxy resin, urethane, silicone, acrylic, polyimide, etc., as well as thermosetting resin and thermoplastic resin. It is preferable to select a binder resin having a low Young's modulus so that the elastic modulus of the wiring pattern 30 in the coated state is equal to or smaller than the elastic modulus of the base substrate 10. One type of binder resin may be used, or multiple types of binder resins may be mixed and used. The molecular chain constituting the binder resin may be linear or branched. The number average molecular weight of the binder resin is preferably 3,000 or more and 100,000 or less, and more preferably 8,000 or more and 50,000 or less. The molecular weight distribution of the binder resin is not particularly limited, but is preferably less than 2.00, more preferably 1.60 or less, and even more preferably 1.40 or less, for example. The viscosity of the wiring material 32 before the heat treatment is preferably 100 dPa·s to 500 dPa·s, more preferably 200 dPa·s to 300 dPa·s, where the viscosity is measured using a rotational viscometer at 25°C. By using such a wiring material 32, the structural strength of the formed wiring pattern 30 can be ensured while the flexibility, stretchability, and adhesion to the base substrate 10 of the wiring pattern 30 can be sufficiently achieved.

[0018] The method of forming the wiring pattern 30 is not particularly limited, but for example, the wiring pattern 30 can be formed by a printing method. That is, the wiring pattern 30 of this embodiment is a printed pattern formed by printing and applying an elastic wiring material 32. The printing method is not particularly limited, but examples include screen printing, inkjet printing, gravure printing, and offset printing. Among these, in the case of this embodiment, screen printing is preferably used from the viewpoint of the fine resolution and stability of the wiring pattern 30. However, in the present invention, for example, when a conductive nano-ink is used as the wiring material 32, the conductive nano-ink may be filled into the groove 20 by dispensing.

[0019] 1, the flexible transparent wiring substrate 100 includes an insulating cover 50 that covers the upper surface 10a of the base material 10 and the wiring pattern 30. Note that the insulating cover 50 is not shown in FIG. According to this configuration, the insulating cover 50 can provide good protection for the wiring pattern 30 .

[0020] For example, the insulating cover 50 covers the entire area in which the wiring pattern 30 is formed in a plan view. The insulating cover 50 has openings (not shown) for arranging, for example, connection terminals of an external device and land portions. More specifically, for example, in the wiring pattern 30, a portion constituting a connection terminal with an external device is exposed from the insulating cover 50 through the openings of the insulating cover 50. The insulating cover 50 may be made of the same material as the base substrate 10, or may be made of a material different from that of the base substrate 10. The insulating cover 50 may be, for example, a single layer of the same type of resin as the base substrate 10, or may be a layer containing a resin other than the same type of resin as the base substrate 10.

[0021] The flexible transparent wiring board 100 includes a first adhesive layer (not shown) formed on, for example, the surface of the insulating cover 50 facing the base substrate 10 (the lower surface in this embodiment). The insulating cover 50 is attached to the upper surface 10a of the base substrate 10 by a first adhesive layer. In the present invention, the flexible transparent wiring board 100 may further include a second adhesive layer (not shown) formed on, for example, the surface of the insulating cover 50 opposite to the surface on the base substrate 10 side (the upper surface in this embodiment). In this case, the flexible transparent wiring board 100 is attached to an object via the second adhesive layer. The first and second pressure-sensitive adhesive layers are formed, for example, by coating an adhesive material. The adhesive material is not particularly limited, but for example, an acrylic resin can be used.

[0022] The thickness dimension of the base substrate 10 is not particularly limited, but is preferably, for example, 25 μm or more and 150 μm or less, and more preferably 50 μm or more and 125 μm or less. The thickness dimension of the insulating cover 50 is not particularly limited, but is preferably, for example, 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 20 μm or less.

[0023] In this embodiment, as shown in FIG. 3(a), it is preferable that the upper surface 35 of the wiring structuring material 32 is a concave surface recessed toward the center in the width direction. This allows a layer other than the wiring constituent material 32, such as a carbon layer 41 described below, to be formed in the groove 20. However, in the present invention, the upper surface 35 of the wiring component material 32 may be flat and flush with the upper surface 10a of the base substrate 10, for example, as shown in FIG. 1 and FIG. 4(a).

[0024] In addition, in this embodiment, as shown in FIG. 3(b), the height position of the upper surface 35 of the wiring material 32 may be, for example, lower than the height position of the opening 21 of the groove 20, and the carbon layer 41 formed on the wiring material 32 may be disposed within the groove 20. As a result, the opening 21 of the groove 20 is closed by the carbon layer 41, so that the occurrence of ion migration in the wiring material 32 in the groove 20 can be suppressed. In addition, since the height position of the upper surface 35 of the wiring material 32 is lower than the height position of the opening 21 of the groove 20, the carbon layer 41 can be formed on the wiring material 32 with a sufficient thickness while preventing the carbon layer 41 from protruding out of the groove 20. In addition, for example, it is possible to suppress the formation of protuberances on a part (typically, the outer peripheral edge) of the upper surface of the wiring constituent material 32. Note that the protuberances referred to here refer to upward protruding burrs (protrusions) formed when the wiring constituent material 32 is filled into the groove 20. When the carbon layer 41 is formed on the wiring material 32 , the wiring pattern 30 is formed by the wiring material 32 and the carbon layer 41 . The carbon layer 41 is configured to include, for example, carbon particles and a binder resin. The carbon layer 41 is a coating film that is formed by being hardened through a heat treatment (for example, a drying treatment).

[0025] In the present invention, when the carbon layer 41 is formed on the wiring material 32, it is preferable that at least the upper surface 35 of the wiring material 32 is a concave surface recessed toward the center in the width direction, or the height position of the upper surface 35 is lower than the height position of the opening 21 of the groove 20. More preferably, the upper surface 35 of the wiring material 32 is a concave surface recessed toward the center in the width direction, and the height position of the upper surface 35 is lower than the height position of the opening 21 of the groove 20.

[0026] In this embodiment, the wiring pattern 30 is opaque, and as shown in FIG. 2, in plan view, the area of ​​the transparent region where the wiring pattern 30 is not formed is larger than the area of ​​the region where the wiring pattern 30 is formed. According to such a configuration, the structural strength of the wiring pattern 30 can be ensured, while the transparency of the entire flexible transparent wiring substrate 100 can be satisfactorily ensured.

[0027] 1 and 3(a), in a cross section perpendicular to the extension direction of the groove 20, the groove 20 is formed in a V-shape that narrows in the depth direction (in the case of this embodiment, the downward direction in FIG. 1). More specifically, the width of the groove 20 (width W1 shown in FIG. 3(a)) gradually decreases in the depth direction (downward). Note that, although an example in which the lower end of the groove 20 has a sharp shape is shown in FIG. 1 and FIG. 3(a), in the present invention, the lower end of the groove 20 may have, for example, a rounded shape.

[0028] Here, the depth of the groove 20 (depth D1 shown in FIG. 3(a)) is, for example, less than the thickness of the base substrate 10 (T1 shown in FIG. 1). This allows the wiring material 32 to be satisfactorily filled into the grooves 20, thereby forming the wiring pattern 30.

[0029] The width W1 of the groove 20 is, for example, 50 μm or less. This makes it possible to prevent the wiring pattern 30 from impairing the transparency, stretchability, and flexibility of the base substrate 10.

[0030] In this embodiment, the depth D1 of the groove 20 is 80% or more of the width W1 of the groove 20. This makes it possible to form the wiring pattern 30 with a narrow width while ensuring a sufficient cross-sectional area of ​​the wiring pattern 30 and reduce the electrical resistance.

[0031] Furthermore, the depth D1 of the groove 20 is preferably greater than the width W1 of the groove 20, for example. By doing so, while forming the wiring pattern 30 to have a narrow width, it is possible to more satisfactorily ensure the cross-sectional area of ​​the wiring pattern 30 and further reduce the electrical resistance.

[0032] Hereinafter, a method for producing a flexible transparent wiring substrate 100 according to this embodiment (hereinafter, sometimes referred to as this method) will be described with reference to FIG. 5(a) to FIG. 9(c). This method involves the steps of preparing a laminate 150 having a base substrate 10 and a protective layer 60, patterning a groove 20 in the base substrate 10, forming a wiring pattern 30, and peeling the protective layer 60 from the base substrate 10, in that order.

[0033] First, in the step of preparing the laminate 150, as shown in Fig. 5(a), the protective layer 60 is disposed on the upper surface 10a of the base substrate 10. Then, the protective layer 60 and the base substrate 10 are fused to each other by applying heat and pressure using a film laminator or the like. As the film laminator, for example, a vacuum laminator (not shown) is preferably used. By doing so, it is possible to prevent air from being interposed between the base substrate 10 and the protective layer 60, and to ensure good adhesion between the base substrate 10 and the protective layer 60.

[0034] The protective layer 60 may be made of the same material as the base substrate 10, or may be made of a material different from that of the base substrate 10. When made of a material different from that of the base substrate 10, the protective layer 60 is preferably made of a resin material having a high absorbance at the wavelength of the laser light 200 described later.

[0035] Moreover, the protective layer 60 has, for example, an easily peelable adhesive layer (not shown), and is removably attached to the base material 10 via the adhesive layer. Here, the “easy peelability” of the adhesive layer is not limited as long as it is a property that allows the protective layer 60 to be peeled off from the base substrate 10 by physical processing (e.g., application of physical force) after the wiring component material 32 is printed or dried. The adhesive having such easy peelability is not particularly limited, but for example, acrylic, rubber, urethane, etc., can be used.

[0036] Next, in the process of patterning the grooves 20, as shown in FIG. 5(b), the grooves 20 are patterned in the base substrate 10 by irradiating the base substrate 10 with laser light 200 through the protective layer 60 of the laminate 150. In the present embodiment, the process of patterning the groove 20 forms the through hole 62 in the protection layer 60, and the groove 20 communicating with the through hole 62 is formed in the base substrate 10. More specifically, the laser processed groove 160 formed in a narrow V-shape in the depth direction is formed in the laminate 150 by irradiating the laser light 200. In the laser processed groove 160, the portion on the irradiation surface 151 side (the upper portion in the present embodiment) constitutes the through hole 62 of the protection layer 60, and the portion on the opposite side to the irradiation surface 151 side (the lower portion in the present embodiment) constitutes the groove 20 of the base substrate 10, based on the boundary surface between the base substrate 10 and the protection layer 60. Therefore, the width W1 of the groove 20 (see FIG. 3(a) and FIG. 3(b)) is smaller than the width W2 of the through hole 62 (see FIG. 8(a)). Therefore, compared to forming the grooves 20 by directly irradiating the laser light 200 onto the base material 10 (without passing through the protective layer 60), it is possible to form a narrower groove 20, and therefore a narrower wiring pattern 30. Furthermore, for example, it is possible to easily form the groove 20 having a width W1 smaller than the beam diameter (diameter R1 of the laser light 200) of the laser processing device used. In addition, in this method, by adjusting the thickness dimension of the protective layer 60, i.e., by adjusting the ratio of the depth of the through hole 62 in the laser-processed groove 160 to the depth of the groove 20, the width W1 of the groove 20 to be formed can also be adjusted.

[0037] In this method, it is preferable to set the processing conditions of the laser light 200 so that the depth D1 of the groove 20 to be formed is smaller than the thickness dimension of the base substrate 10 and is approximately constant regardless of the position of the groove 20 in the extension direction. The depth of the laser processed groove 160 (and thus the depth D1 of the groove 20) is preferably adjusted by multiple scans using a step-and-repeat function of the laser device (not shown) used. This facilitates fine adjustment of the depth of the laser processed groove 160 (depth D1 of the groove 20). Furthermore, when irradiating the laser light 200, damage caused by heat to the base substrate 10 and the protective layer 60 can be further suppressed.

[0038] The width W1 of the groove 20 to be formed is, for example, 50 μm or less as described above. More specifically, in the case of this embodiment, as an example, the diameter R1 of the laser light 200 is 18 μm, and the width W1 of the groove 20 is, for example, about 13 μm. However, in the present invention, in addition to the groove 20 having a width W1 of 50 μm or less, a groove 25 having a width larger than the diameter R1 of the laser light 200 (for example, 50 μm or more) may be formed in the base substrate 10 as shown in FIG. 9(a). In this case, the wiring pattern 30 formed in the groove 25 is used as a connection terminal to be connected to, for example, a land portion or a substrate of an electronic device or an electronic component. For example, the wiring pattern 30 (connection terminal) formed in the groove 25 may be locally plated. As shown in FIG. 9(a), the groove 25 is formed, for example, by irradiating the laser beam 200 in an offset manner in the surface direction of the base substrate 10. In this case, while maintaining the state of irradiating the laser beam 200, the irradiation unit (not shown) of the laser processing device may be moved relatively in the surface direction of the base substrate 10, or the operation of moving the irradiation unit relatively in the surface direction of the base substrate 10 in a state where the irradiation of the laser beam 200 is once stopped and then irradiating the laser beam 200 again may be repeated multiple times. According to such a method, for example, by adjusting the moving distance of the irradiation unit of the laser processing device or the offset width (W4 shown in FIG. 9(a)) between the laser beams 200, the width of the groove 25 can be adjusted according to the dimensions of the electronic device to be connected, the land portion of the electronic component, the board, etc. Furthermore, by setting the offset width W4 to be equal to or smaller than the diameter R1 of the laser beam 200, the laser processed groove 160 (and thus the groove 25) formed in the laminate 150 can be made to have a narrow V-shape in the depth direction. When the offset width W4 is equal to or smaller than the diameter R1 of the laser beam 200, the processing speed of the laser beam 200 in the groove depth direction becomes faster compared to when the groove 20 is formed. For this reason, when the groove 25 is formed, it is preferable to set the processing conditions of the laser beam 200 separately from the processing conditions of the laser beam 200 when the groove 20 is formed.

[0039] In this method, for example, an ultrashort pulse laser is used as the laser light 200. This makes it possible to easily form narrow grooves 20 while suppressing damage caused by heat to the base substrate 10 without using an exposure mask or the like. Therefore, the transparency of the base substrate 10 can be maintained at a good level, and the variation in the width W1 of the groove 20 can be suppressed. Furthermore, due to the multiphoton absorption effect of the ultrashort pulse laser, it is possible to laser process the transparent base substrate 10 in sequence from the irradiation surface 151 to the bottom surface of the groove 20, so that the variation in the depth D1 of the groove 20 (variation in the extension direction) can also be suppressed by adjusting the laser output. Therefore, the variation in the electrical resistance of the wiring pattern 30 formed by the wiring constituent material 32 filled in the groove 20 can also be suppressed.

[0040] Next, in the process of forming the wiring pattern 30, the wiring material 32 is filled into the grooves 20 and dried to form the wiring pattern 30. More specifically, as shown in FIG. 5(c), the wiring material 32 is supplied onto the protective layer 60, and while the tip of the squeegee 250 is in contact with the upper surface of the protective layer 60, the squeegee 250 is moved along the upper surface of the protective layer 60 (by squeegeeing), thereby filling the inside of the laser-machined groove 160 (the through hole 62 and the groove 20) with the wiring material 32. This allows the narrow wiring pattern 30 to be easily and satisfactorily formed without using a screen printing plate (not shown). In this case, the screen printing plate may be used repeatedly as an area for temporarily holding or evacuating the wiring material 32 instead. More specifically, the screen printing plate used has an opening that is larger than the area encompassing the entire groove 20 in the base substrate 10 in a plan view and smaller than the outer dimensions of the base substrate 10. This allows the wiring material 32 to be temporarily held or evacuated on the outer periphery of the opening of the screen printing plate. After squeegeeing the wiring material 32, residues of the metal particles 32a and binder resin of the wiring material 32 are generated on the protective layer 60, but as described below, in the process of peeling off the protective layer 60, the metal particles 32a and binder resin are peeled off together with the protective layer 60. This makes it possible to prevent the metal particles 32a and binder resin of the wiring material 32 from remaining on the wiring pattern 30 and the base substrate 10. In addition, when filling with the wiring material 32 containing metal particles 32a, the base substrate 10 can be protected by the protective layer 60, so that the wiring pattern 30 can be formed while maintaining good transparency and appearance of the base substrate 10.

[0041] Here, the process of forming the wiring pattern 30 includes a drying process (heat treatment process) that is performed on the wiring constituent material 32 after filling with the wiring constituent material 32. The wiring pattern 30 (wiring constituent material 32) is in a paste state after printing and before the drying process, and is heated in the drying process to become a dried state. In the case of this embodiment, for example, an oven dryer or a conveyor furnace is used in the drying process. More specifically, as shown in Figures 8(a) to 8(c), the entire wiring material 32 filled in the laser processed groove 160 (through hole 62 and groove 20) shrinks in thickness as it dries, and is substantially contained within the groove 20. More specifically, the height position of the upper surface 35 of the wiring material 32 drops (retracts) from the state shown in Figure 8(a) to the state shown in Figures 8(b) and 8(c). In a completely dried state, the upper surface 35 of the wiring material 32 may be flush with the upper surface 10a (upper surface) of the base substrate 10, or may be located lower than the upper surface 10a. As described above, the upper surface 35 of the wiring component 32 is preferably a concave surface recessed toward the center in the width direction. In the case of this embodiment, as an example, by setting the above squeegeeing conditions in accordance with the post-drying characteristics of the wiring constituent material 32 used, the shape of the upper surface 35 of the wiring constituent material 32 after complete drying can be made into a concave surface as described above. As shown in FIGS. 9(a) to 9(c), in the case of groove 25 having a width greater than diameter R1 of laser light 200, wiring material 32 is filled in the same manner as groove 20, and wiring pattern 30 is formed.

[0042] Next, in the step of peeling off the protective layer 60, the protective layer 60 is peeled off from the base substrate 10 as shown in FIG. 6(a). In the present invention, the step of peeling off the protective layer 60 may be performed after the step of forming the wiring pattern 30, or may be performed during the step of forming the wiring pattern 30. More specifically, when the drying process is performed during the process of forming the wiring pattern 30, for example, the above-mentioned drying process includes a pre-drying process and a complete drying process, and each process is performed in the order of the pre-drying process, the process of peeling off the protective layer 60, and the complete drying process. In the preliminary drying process, the heating temperature and heating time are set to a level that suppresses the fluidity of the wiring material 32, and the wiring material 32 is semi-dried (semi-cured) by the heating condition. After the protection layer 60 is peeled off, the wiring material 32 is completely dried (completely cured) in the complete drying process. As a result, even if the heating temperature of the wiring constituent material 32 (the temperature at which the wiring constituent material 32 completely dries and hardens) is high, the above-mentioned adhesive layer (not shown) of the protective layer 60 can be prevented from hardening excessively when the wiring constituent material 32 is heated in the process of forming the wiring pattern 30, so that the protective layer 60 can be easily peeled off from the base substrate 10 in the process of peeling off the protective layer 60.

[0043] Furthermore, when the carbon layer 41 is formed on the wiring constituent material 32, the step of forming the carbon layer 41 may be performed after the preliminary drying step or after the complete drying step. In the step of forming the carbon layer 41, the carbon layer 41 is filled on the upper surface 35 of the wiring constituent material 32 in a semi-dried or completely dried state. After filling, the carbon layer 41 is in a paste state before the heat treatment, and becomes dry by being heated by the heat treatment. The heat treatment of the carbon layer 41 may be performed simultaneously with the wiring pattern 30 in a complete drying step of the wiring pattern 30, or a drying step (heat treatment step) of the carbon layer 41 may be performed separately after the complete drying step. The method for forming the carbon layer 41 is not particularly limited, but may be, for example, a printing method. The printing method is not particularly limited, but may be, for example, a screen printing method, an inkjet printing method, a gravure printing method, an offset printing method, or the like.

[0044] In the case of this embodiment, as an example, the heating in the preliminary drying step is performed at a temperature of preferably 70° C. or more and 250° C. or less, more preferably 80° C. or more and 200° C. or less, for about 5 to 10 minutes. As an example, the heating in the complete drying step is preferably performed at a temperature of 70° C. or higher and 250° C. or lower, more preferably 80° C. or higher and 200° C. or lower, for about 30 to 90 minutes. However, in the present invention, the heating conditions in the drying step can be appropriately set depending on the materials of the wiring constituent material 32 and the base substrate 10, etc.

[0045] Here, in the case of this embodiment, as shown in Figures 7, 8(a) and 8(b), it is preferable that the inclination angle of the side wall of the through hole 62 in the protective layer 60 is steeper than the inclination angle of the side wall of the groove 20 in the base substrate 10. According to this configuration, when the wiring material 32 filled in the laser processed groove 160 (through hole 62 and groove 20) shrinks in the drying process, a part of the wiring material 32 can smoothly slide down into the groove 20 along the through hole 62. Therefore, the entire wiring material 32 can be well accommodated in the groove 20 in the dry state. However, the present invention is not limited to this example, and the inclination angle of the side wall of the groove 20 in the base substrate 10 may be steeper than the inclination angle of the side wall of the through hole 62 in the protective layer 60, or the inclination angle of the side wall of the through hole 62 in the protective layer 60 and the inclination angle of the side wall of the groove 20 in the base substrate 10 may be equal to each other.

[0046] Next, in this method, for example, as shown in Fig. 6(b), a step of attaching an insulating cover 50 onto the upper surface 10a of the base substrate 10 is performed. As an example, similar to the protective layer 60, the insulating cover 50 and the base substrate 10 are fused to each other by applying heat and pressure using a film laminator or the like. This allows the base substrate 10 and the wiring pattern 30 to be well protected by the insulating cover 50. However, in the present invention, the method does not necessarily include the step of disposing the insulating cover 50 on the upper surface 10a of the base substrate 10. In other words, the flexible transparent wiring substrate 100 does not necessarily have to include the insulating cover 50.

[0047] Here, in the case of this embodiment, as shown in Fig. 4(b), for example, there is a scratch 39 on a side surface 38a of an upper portion 34 of the wiring constituent material 32, but there is no scratch on a side surface 38b of a lower portion 36 of the conductive paste. Note that Fig. 4(b) shows the shape of the scratch 39 in a schematic manner. This allows at least a portion of the side surface 38a of the upper portion 34 of the wiring component 32 to be anchored to the insulating cover 50, thereby improving the peel resistance of the insulating cover 50 to the base substrate 10.

[0048] Thus, this method includes the steps of preparing a laminate comprising a flexible, transparent, and insulating base substrate 10 and a protective layer 60 removably attached to the upper surface 10a of the base substrate 10; patterning grooves 20 in the base substrate 10 by irradiating laser light 200 onto the base substrate 10 through the protective layer 60 of the laminate; filling the grooves 20 with a wiring material 32 and drying it to form a wiring pattern 30; and peeling the protective layer 60 from the base substrate 10. In the step of patterning the grooves 20, the grooves 20 are formed in a narrow V-shape in the depth direction.

[0049] According to this method, it is possible to easily form a narrow wiring pattern 30. This makes it possible to minimize the area in the base substrate 10 where the wiring pattern 30 is formed, thereby preventing the transparency, stretchability, and bending resistance of the base substrate 10 from being impaired. That is, according to this embodiment, it is possible to realize the flexible transparent wiring substrate 100 having good transparency, stretchability, and bending resistance. Furthermore, compared to typical methods for manufacturing flexible transparent wiring boards using screen printing or inkjet printing, this method does not require tools such as a screen plate or an exposure mask, and the flexible transparent wiring board 100 can be manufactured using only a film laminator, a laser processing device, a screen printer, and drying equipment. In other words, the number of devices and tools required for manufacturing the flexible transparent wiring board 100 can be reduced, so that the flexible transparent wiring board 100 can be manufactured with higher productivity. Furthermore, compared to manufacturing methods for flexible transparent wiring substrates using general subtractive, additive, semi-additive, etc., this method allows the wiring pattern 30 to be formed without using chemicals or water, thereby suppressing the generation of waste liquid accompanying the formation of the wiring pattern 30. Furthermore, since there is no need to control the temperature of the waste liquid, the energy consumed in the manufacture of the flexible transparent wiring substrate 100 can be effectively reduced, and the burden on the environment can also be reduced.

[0050] 10(a) to 12 show enlarged photographs of the flexible transparent wiring substrate 100 actually obtained by the above-mentioned manufacturing method of the flexible transparent wiring substrate 100. Note that Fig. 10(a) to Fig. 12 show images of a cross section perpendicular to the extension direction of the groove 20. As described above, in this method, the laser beam 200 is irradiated onto the base substrate 10 through the protective layer 60 of the laminate 150, thereby forming a pattern of the grooves 20 on the base substrate 10. For this reason, as shown in FIG. 10(a), the through-holes 62 are first formed in the protective layer 60 of the base substrate 10 and the protective layer 60. Then, as shown in FIG. 10(b) and FIG. 10(c), the grooves 20 are gradually formed in the base substrate 10 by the laser beam 200. Then, as shown in FIG. 10(d), the laser-processed grooves 160 formed in a narrow V-shape in the depth direction are formed in the laminate 150, and the grooves 20 formed in a narrow V-shape in the depth direction are formed in the base substrate 10. This makes it possible to form narrower grooves 20, and therefore wiring patterns 30, compared to the case where the grooves 20 are formed by directly irradiating the base substrate 10 with laser light 200 (without going through the protective layer 60), as described above. FIG. 11 shows a state in which the wiring pattern 30 is formed by filling the grooves 20 thus obtained with a wiring material 32 and drying it, and the protective layer 60 is peeled off from the base material 10. As shown in FIG. 11, the upper surface 35 of the wiring component 32 is a concave surface recessed toward the center in the width direction. This makes it easy to form layers other than the wiring constituent material 32, such as the carbon layer 41, in the grooves 20 (which are not yet formed in the state shown in FIG. 11), as described above. However, in the present invention, it is not necessary to form layers other than the wiring material 32, such as the carbon layer 41, on the upper surface 35 of the wiring material 32, which is a concave surface recessed toward the center in the width direction as shown in Fig. 11. In this case, for example, a structure in which the insulating cover 50 directly covers the wiring material 32 can be used. FIG. 12 shows a state in which a carbon layer 41 is further filled on the upper surface 35 of the wiring constituent material 32 and dried, and the protective layer 60 is peeled off from the base material 10. As shown in FIG. 12, the height position of the upper surface 35 of the wiring structuring material 32 is lower than the height position of the opening 21 of the groove 20 . As a result, as described above, the opening 21 of the groove 20 is closed by the carbon layer 41, which makes it possible to suppress the occurrence of ion migration in the wiring material 32 in the groove 20. In addition, since the height position of the upper surface 35 of the wiring material 32 is lower than the height position of the opening 21 of the groove 20, it is possible to form the carbon layer 41 of sufficient thickness on the wiring material 32 while suppressing the carbon layer 41 from protruding from the groove 20.

[0051] Although the embodiments have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0052] The above embodiment encompasses the following technical ideas. (1) a flexible, transparent, and insulating base material having a groove pattern formed on its upper surface; a wiring pattern formed by filling the groove with a wiring material; and Equipped with The groove is formed in a narrow V-shape in the depth direction of the flexible transparent wiring substrate. (2) A flexible transparent wiring board according to (1), wherein the upper surface of the wiring material is a concave surface recessed toward the center in the width direction. (3) A flexible transparent wiring board according to (1) or (2), in which the side surface of the upper portion of the wiring structuring material has scratches, and the side surface of the lower portion of the wiring structuring material does not have scratches. (4) the height position of the upper surface of the wiring constituent material is lower than the height position of the opening of the groove; The flexible transparent wiring board according to (1) or (2), wherein a carbon layer formed on the wiring material is disposed in the groove. (5) The wiring pattern is opaque; 3. The flexible transparent wiring substrate according to claim 1, wherein, in a plan view, an area of ​​a transparent region where the wiring pattern is not formed is larger than an area of ​​a region where the wiring pattern is formed. (6) The flexible transparent wiring board according to (1) or (2), wherein the depth of the groove is less than the thickness of the base substrate. (7) The flexible transparent wiring board according to (1) or (2), wherein the width of the groove is 50 μm or less. (8) The flexible transparent wiring board according to (1) or (2), wherein the depth of the groove is 80% or more of the width of the groove. (9) The flexible transparent wiring substrate according to (8), wherein the depth of the groove is greater than the width of the groove. (10) The flexible transparent wiring board according to any one of (1) to (9), wherein the wiring material has high flexibility so as to be able to follow the bending deformation of the base material. (11) The flexible transparent wiring board according to any one of (1) to (10), further comprising an insulating cover that covers the upper surface of the base material and the wiring pattern. (12) preparing a laminate including a flexible, transparent, and insulating base material and a protective layer releasably attached to an upper surface of the base material; forming a pattern of grooves in the base substrate by irradiating the base substrate with laser light through the protective layer of the laminate; filling the grooves with a wiring material and drying it to form a wiring pattern; peeling the protective layer from the base substrate; Equipped with In the step of forming the groove in a pattern, the groove is formed in a narrow V-shape in a depth direction. (13) The method for producing a flexible transparent wiring substrate according to (12), wherein an ultrashort pulse laser is used as the laser light. (14) The step of patterning the grooves A through hole is formed in the protective layer, and the groove communicating with the through hole is formed in the base material, The method for producing a flexible transparent wiring substrate according to (12) or (13), wherein the inclination angle of the sidewall of the through hole is steeper than the inclination angle of the sidewall of the groove. [Explanation of symbols]

[0053] 10 Base Material 10a top surface 20, 25 grooves 21 Aperture 30 Wiring Pattern 32 Wiring construction materials 32a Metal particles 34 Top 35 Top 36 Lower 38a, 38b side 39 Scratches 41 Carbon layer 50 Insulating cover 60 Protection Layer 62 Through hole 100 Flexible transparent wiring board 150 Laminate 151 Irradiation surface 160 Laser-machined groove 200 Laser Light 250 Squeegee D1 Groove depth R1 Laser beam diameter T1 Base material thickness W1 Groove width W2 Through hole width W4 offset width

Claims

1. A flexible, transparent, and insulating base material having a groove pattern formed on an upper surface thereof; a wiring pattern formed by filling the groove with a wiring material; and Equipped with The groove is formed in a narrow V-shape in the depth direction of the flexible transparent wiring substrate.

2. 2. The flexible transparent wiring board according to claim 1, wherein the upper surface of the wiring material is a concave surface recessed toward the center in the width direction.

3. 3. The flexible transparent wiring board according to claim 1, wherein the side surface of the upper portion of the wiring material has scratches, and the side surface of the lower portion of the wiring material has no scratches.

4. the height position of the upper surface of the wiring constituent material is lower than the height position of the opening of the groove; 3. The flexible transparent wiring board according to claim 1, wherein a carbon layer formed on the wiring material is disposed in the groove.

5. The wiring pattern is opaque, 3. The flexible transparent wiring board according to claim 1, wherein, in a plan view, an area of ​​a transparent region where the wiring pattern is not formed is larger than an area of ​​a region where the wiring pattern is formed.

6. The flexible transparent wiring board according to claim 1 or 2, wherein the depth of the groove is less than the thickness of the base material.

7. 3. The flexible transparent wiring board according to claim 1, wherein the groove has a width of 50 [mu]m or less.

8. 3. The flexible transparent wiring substrate according to claim 1, wherein the depth of the groove is 80% or more of the width of the groove.

9. The flexible transparent wiring substrate according to claim 8 , wherein the depth of the groove is greater than the width of the groove.

10. 3. The flexible transparent wiring board according to claim 1, wherein the wiring material has high flexibility so as to be able to follow the bending deformation of the base material.

11. The flexible transparent wiring board according to claim 1 , further comprising an insulating cover that covers the upper surface of the base material and the wiring pattern.

12. A step of preparing a laminate including a flexible, transparent, and insulating base material and a protective layer releasably attached to an upper surface of the base material; forming a pattern of grooves in the base substrate by irradiating the base substrate with laser light through the protective layer of the laminate; filling the grooves with a wiring material and drying it to form a wiring pattern; peeling the protective layer from the base substrate; Equipped with In the step of forming the groove in a pattern, the groove is formed in a narrow V-shape in a depth direction.

13. The method for producing a flexible transparent wiring substrate according to claim 12, wherein an ultrashort pulse laser is used as the laser light.

14. The step of patterning the grooves A through hole is formed in the protective layer, and the groove communicating with the through hole is formed in the base material, 14. The method for producing a flexible transparent wiring substrate according to claim 12, wherein an inclination angle of a side wall of the through hole is steeper than an inclination angle of a side wall of the groove.

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