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

Abstract

The invention provides a flexible transparent wiring substrate and a method for manufacturing the flexible transparent wiring substrate. The flexible transparent wiring substrate is provided with a base substrate and wiring, the base substrate is transparent and has flexibility and insulating properties, a groove is formed in the upper surface of the base substrate, the wiring is formed by a wiring constituent material filled in the groove, and the groove is formed in a V-shape with a width narrowing toward the depth direction.

Description

Cross-reference to related applications: This application claims priority from Japanese Patent Application No. 2023-128329 filed with the Japan Patent Office on August 4, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0001] The present invention relates to a flexible transparent wiring substrate and a method for manufacturing the flexible transparent wiring substrate. Background Art

[0002] The flexible transparent wiring substrate described in JP-A-2011-528502 and JP-A-2006-120888 includes a base substrate having a groove pattern formed on the upper surface and a wiring pattern formed of a wiring constituent material filled in the groove. The width of the groove is substantially constant regardless of the position in the depth direction.

[0003] According to the research of the inventors of the present application, the flexible transparent wiring substrates described in Japanese Unexamined Patent Application Publication No. 2011-528502 and Japanese Unexamined Patent Application Publication No. 2006-120888 have room for improvement in terms of achieving good transparency, stretchability and bending resistance of the flexible transparent wiring substrate. Summary of the invention

[0004] The flexible transparent wiring substrate of an embodiment of the present invention is configured as follows: it includes a base substrate and wiring, the base substrate is transparent, flexible and insulating, a groove is formed on the upper surface of the base substrate, the wiring is formed by a wiring constituent material filled in the groove, and the groove is formed in a V-shape whose width becomes narrower toward the depth direction.

[0005] The present invention relates to a flexible transparent wiring substrate having a structure capable of realizing excellent transparency, stretchability and bending resistance, and a method for manufacturing the flexible transparent wiring substrate.

[0006] The flexible transparent wiring substrate of the present invention comprises a base substrate and wiring, wherein the base substrate is transparent, flexible and insulating, a groove is formed on the upper surface of the base substrate, the wiring is formed by a wiring constituent material filled in the groove, and the groove is formed in a V-shape whose width becomes narrower toward the depth direction.

[0007] The manufacturing method of the flexible transparent wiring substrate of the present invention comprises: preparing a laminated body, wherein the laminated body has a transparent, flexible and insulating base substrate, and a protective layer attached to the upper surface of the base substrate in a removable manner; irradiating the base substrate with a laser through the protective layer of the laminated body, thereby forming a groove in the base substrate; filling the groove with a wiring constituent material and drying it to form a wiring; and peeling the protective layer from the base substrate to form the groove into a V-shaped shape whose width becomes narrower toward the depth direction.

[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 It is a cutaway end view of a flexible transparent wiring substrate, showing a cross section perpendicular to the extending direction of the wiring pattern. Figure 2 is a schematic top view of a flexible transparent wiring substrate. Figure 3A and Figure 3B yes Figure 1 A partial enlarged view of section A is shown. Figure 3A Indicates that the upper surface of the wiring component material is a concave surface that is recessed toward the center in the width direction. Figure 3B This indicates a state in which the height position of the upper surface of the wiring constituent material is lower than the height position of the opening of the groove. Figure 4A and Figure 4B This is a partial enlarged view of the wiring pattern. Figure 4A This is a cross-sectional view perpendicular to the extension direction of the wiring pattern. Figure 4B is along Figure 4A This is a side view of the wiring pattern viewed in the direction of arrow A. Figure 5A , Figure 5B and Figure 5C This is a cutaway end view for explaining a method for manufacturing a flexible transparent wiring substrate. Figure 5A represents the process of preparing a laminated body, Figure 5B represents the process of forming the groove pattern, Figure 5C This shows the process of forming a wiring pattern. Fig. 6A and Figure 6B This is a cutaway end view for explaining a method for manufacturing a flexible transparent wiring substrate. Fig. 6A Indicates the process of peeling off the protective layer. Figure 6B This shows the step of attaching the insulating cover to the base substrate. Figure 7 It is a partially enlarged view of a cutaway end surface of a flexible transparent wiring substrate, and shows an example in which the groove is formed in a U-shape whose width becomes narrower toward the depth direction. Fig. 8A , Figure 8B and Figure 8C This is a cutaway end view for explaining a method for manufacturing a flexible transparent wiring substrate, and shows a process of forming a groove having a width smaller than the diameter of a laser. Fig. 9A , Fig. 9B and Fig. 9CThis is a cutaway end view for explaining a method for manufacturing a flexible transparent wiring substrate, and shows a process of forming a groove having a width larger than the diameter of a laser. Fig. 10A , Fig. 10B , Fig. 10C and Fig. 10D This is a diagram showing an image of a cross section of a flexible transparent wiring substrate in the step of forming a groove pattern, showing a process of forming laser processed grooves in a laminate by irradiating a laser. Fig.11 This is a diagram showing an image obtained by photographing a cross section of a flexible transparent wiring substrate, showing a state in which the upper surface of the wiring constituent material is a concave surface depressed toward the center in the width direction. Fig.12 This figure shows an image obtained by photographing a cross section of a flexible transparent wiring substrate, and shows a state where a carbon layer is formed on a wiring constituent material. DETAILED DESCRIPTION In the detailed description below, for the purpose of illustration, in order to provide a thorough understanding of the disclosed embodiments, many specific details are set forth. However, it is apparent that one or more embodiments may be implemented without these specific details. In other cases, in order to simplify drawing, well-known structures and devices are schematically shown.

[0010] Hereinafter, the embodiments of the present invention will be described using the drawings. In addition, in all the drawings, the same components are denoted by the same reference numerals, and their description is appropriately omitted. In the following description of the positional relationship between the components of the flexible transparent wiring substrate 100, Figure 1 The upper side in the figure is referred to as the upper side or the upper side, and the opposite side is referred to as the lower side or the lower side. However, these directions are defined for convenience and do not limit the directions of the flexible transparent wiring substrate 100 during manufacture and use.

[0011] like Figure 1 to Figure 3B As shown, the flexible transparent wiring substrate 100 of this embodiment includes a base substrate 10 and wiring (wiring pattern 30), wherein the base substrate 10 is transparent, flexible and insulating, and a groove 20 is formed on the upper surface 10a, and the wiring is formed by a wiring constituent material 32 filled in the groove 20. In addition, in this embodiment, if Figure 2 The pattern of the groove 20 is formed as shown. In the present embodiment, the wiring pattern filled in the groove 20 may be referred to as a wiring pattern 30. The pattern of the groove 20 and the wiring pattern 30 are not limited to Figure 2 The pattern shown may be any desired pattern. For example, the plurality of wiring patterns 30 are not limited to Figure 2The linear pattern shown in FIG. 1 may also be a bent pattern. In addition, the intervals between the wiring patterns 30 are not limited to Figure 2 Equal intervals shown. The groove 20 is formed in a V-shape whose width becomes narrower toward the depth direction. In addition, the "transparent" mentioned here means transparent to visible light. In addition, the "upper surface of the base substrate 10" mentioned here refers to the surface on the side where a part of the wiring pattern 30 is exposed from the base substrate 10, among the main surfaces of the front and back sides of the base substrate 10. However, the upper surface is defined here for the sake of convenience and does not limit the direction of the flexible transparent wiring substrate 100 during manufacturing and use. In addition, the "V-shaped" mentioned here also includes, for example Figure 7 The U-shaped shape shown.

[0012] According to the present embodiment, the groove 20 is formed into a V-shaped shape whose width becomes narrower toward the depth direction. Therefore, even when the groove 20 is set to be narrow in width, when the wiring constituent material 32 is filled into the groove 20, the wiring constituent material 32 can smoothly flow into the entire interior of the groove 20 by capillary phenomenon. Therefore, it is possible to easily form a wiring pattern 30 with a narrow width. As a result, the formation area of ​​the wiring pattern 30 in the base substrate 10 can be kept to a minimum, so that the transparency, elasticity and bending resistance of the base substrate 10 can be suppressed from being damaged. That is, according to the present embodiment, good transparency, elasticity and bending resistance of the flexible transparent wiring substrate 100 can be achieved.

[0013] The flexible transparent wiring substrate 100 of the present embodiment is used as a wiring substrate for, for example, a vehicle-mounted glass-bonded antenna, a glass-bonded sensor, a switch, a wearable device, a touch screen, and the like. In addition, as an example, the flexible transparent wiring substrate 100 is used by being attached to an attachment object. In this case, the flexible transparent wiring substrate 100 expands and contracts and bends following the unevenness and deformation of the attachment object.

[0014] The base substrate 10 is, for example, a relatively thin film-like substrate having its front and back surfaces as main surfaces. The base substrate 10 is made of a transparent resin material having insulation 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 for example, polyimide (PI), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), fluorine resin (PTFE), or a resin material containing these materials may also be used.

[0015] like Figure 1 As shown, 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 is, for example, a semiconductor chip, a ceramic capacitor, a resistor, or the like. As described above, the wiring pattern 30 is formed by filling the groove 20 of the base substrate 10 with the wiring constituent material 32. More specifically, the wiring pattern 30 is a coating film formed of the wiring constituent material 32. Figure 1 and Figure 4A As shown, in a cross section perpendicular to the extending direction of the wiring pattern 30 (for example, along Figure 2 In the cross section taken along the line AA shown in FIG. 1 , the wiring pattern 30 is also formed in a V-shape whose width becomes narrower toward the depth direction, similar to the groove 20. In addition, Figure 4A and Figure 4B In the figure, only the wiring pattern 30 is selectively shown, and the base substrate 10 and the insulating cover 50 described later are omitted.

[0016] The wiring constituent material 32 has flexibility that allows it to follow the bending deformation of the base substrate 10 . By making the wiring material 32 highly flexible, the wiring pattern 30 formed of the wiring material 32 can also well follow the bending deformation of the base substrate 10. Therefore, the flexible transparent wiring substrate 100 can achieve better stretchability and bending resistance.

[0017] In the present embodiment, as an example, the wiring constituent material 32 is a conductive paste and is a coating formed by curing through a heat treatment (eg, a drying step described later). However, in the present invention, the wiring constituent material 32 may be, for example, a conductive nano ink. In more detail, the wiring constituent material 32 (conductive paste) is constituted to include, for example, conductive particles and a binder resin. In addition, the wiring constituent material 32 may also include, for example, a surfactant. In addition, when the wiring constituent material 32 is conductive nano ink, the wiring constituent material 32 (conductive nano ink) is constituted to include conductive particles, a solvent, and a dispersant. The conductive particles are metal particles 32 a of silver, gold, or copper, for example. Examples of the binder resin include epoxy resin, polyurethane, silicone, acrylic acid, polyimide, and thermosetting resins and thermoplastic resins. In addition, as the binder resin, it is desirable to select a low Young's modulus binder resin in which the elastic modulus of the wiring pattern 30 in a film-coated state is equal to or smaller than the elastic modulus of the base substrate 10. One binder resin may be used, or a plurality 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, for example, preferably less than 2.00, more preferably 1.60 or less, and further preferably 1.40 or less. The viscosity of the wiring constituent material 32 before the heat treatment is preferably 100 dPa·s to 500 dPa·s, more preferably 200 dPa·s to 300 dPa·s. The viscosity here is a value measured at 25°C using a rotational viscometer. By using such a wiring constituent material 32 , the structural strength of the formed wiring pattern 30 can be ensured, and the flexibility and stretchability of the wiring pattern 30 can be sufficiently achieved, and further, sufficient adhesion to the base substrate 10 can be achieved.

[0018] Although the method for forming the wiring pattern 30 is not particularly limited, the wiring pattern 30 can be formed, for example, by a printing method. That is, the wiring pattern 30 of the present embodiment is a printed pattern formed by printing and coating a wiring constituent material 32 having elasticity. Although the printing method is not particularly limited, for example, screen printing, inkjet printing, gravure printing, and offset printing can be cited. Among them, in the case of the present embodiment, screen printing is preferably used from the viewpoint of 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 constituent material 32, the conductive nano ink can also be filled into the groove 20 by dispensing.

[0019] Furthermore, if Figure 1 As shown in FIG. 1 , in the case of this embodiment, the flexible transparent wiring substrate 100 includes an insulating cover 50 covering the upper surface 10a of the base substrate 10 and the wiring pattern 30. Figure 2 In the figure, the insulating cover 50 is omitted. According to such a structure, the wiring pattern 30 can be well protected by the insulating cover 50 .

[0020] For example, in a plan view, the insulating cover 50 covers the entire formation region of the wiring pattern 30 . For example, an opening (not shown) for arranging connection terminals or lands of external devices is formed in the insulating cover 50. More specifically, for example, a portion of the wiring pattern 30 constituting a connection terminal connected to an external device is exposed from the insulating cover 50 through the opening 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 the base substrate 10. In addition, the insulating cover 50 may be, for example, a single layer of the same resin as the base substrate 10, or may be a layer containing a resin other than the same resin as the base substrate 10.

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

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

[0023] Here, in the case of this embodiment, if Figure 3AAs shown, it is preferred that the upper surface 35 of the wiring constituent material 32 is a concave surface that is recessed toward the central portion in the width direction of the wiring constituent material 32. As a result, layers other than the wiring constituent material 32 described below, such as the carbon layer 41, can be formed in the groove 20. The central portion in the width direction of the wiring constituent material 32 may also be referred to as the central portion in the width direction of the groove 20. In addition, in the following description, the central portion in the width direction of the wiring constituent material 32 may be simply referred to as the central portion in the width direction. However, in the present invention, the upper surface 35 of the wiring component material 32 may be, for example, Figure 1 and Figure 4A The illustrated embodiment is flat and is arranged flush with the upper surface 10 a of the base substrate 10 .

[0024] In addition, in the case of this embodiment, if Figure 3B As shown, the height position of the upper surface 35 of the wiring constituent material 32 may be lower than the height position of the opening 21 of the groove 20 , for example, and the carbon layer 41 formed on the wiring constituent material 32 may be arranged in the groove 20 . Thus, the opening 21 of the groove 20 is closed by the carbon layer 41 , so that ion migration in the wiring constituent material 32 in the groove 20 can be suppressed. Furthermore, since the height position of the upper surface 35 of the wiring constituent material 32 is lower than the height position of the opening 21 of the groove 20 , the carbon layer 41 can be prevented from protruding from the groove 20 and a carbon layer 41 of sufficient thickness can be formed on the wiring constituent material 32 . In addition, for example, it is possible to suppress the formation of a raised corner on a portion (typically the outer peripheral edge) of the upper surface of the wiring component material 32. The raised corner referred to here refers to a burr (protrusion) protruding upward formed when the wiring component material 32 is filled into the groove 20. In addition, when the carbon layer 41 is formed on the wiring constituent material 32 , the wiring pattern 30 is formed of the wiring constituent material 32 and the carbon layer 41 . The carbon layer 41 is constituted by, for example, carbon particles and a binder resin. The carbon layer 41 is a coating film formed by curing by heat treatment (for example, drying treatment).

[0025] In addition, in the present invention, when the carbon layer 41 is formed on the wiring constituent material 32, it is preferred that at least one of the upper surface 35 of the wiring constituent material 32 is a concave surface that is recessed toward the center portion 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. More preferably, the upper surface 35 of the wiring constituent material 32 is a concave surface that is recessed toward the center portion 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 the case of this embodiment, the wiring pattern 30 is opaque. Figure 2 As shown, in a plan view, the area of ​​the transparent region where the wiring pattern 30 is not formed is larger than the area of ​​the opaque region where the wiring pattern 30 is formed. According to such a structure, the structural strength of the wiring pattern 30 can be ensured, and the transparency of the entire flexible transparent wiring substrate 100 can be well ensured.

[0027] like Figure 1 and Figure 3A As shown, in a cross section perpendicular to the extending direction of the groove 20, the groove 20 is formed in the depth direction (in the case of the present embodiment, Figure 1 More specifically, the width of the groove 20 ( Figure 3A The width W1 shown in FIG. 1 gradually decreases toward the depth direction (downward). Figure 1 and Figure 3A , an example in which the lower end of the groove 20 is a sharp shape is shown, but in the present invention, the lower end of the groove 20 may be, for example, rounded.

[0028] Here, the depth of the groove 20 ( Figure 3A The depth D1 shown is, for example, smaller than the thickness of the base substrate 10 ( Figure 1 As a result, the wiring material 32 can be well filled into the groove 20 to form the wiring pattern 30.

[0029] The width W1 of the groove 20 is, for example, 50 μm or less. This can prevent the wiring pattern 30 from damaging the transparency, elasticity, and bending resistance of the base substrate 10 .

[0030] In the present embodiment, the depth D1 of the groove 20 is equal to or greater than 80% of the width W1 of the groove 20. This allows the wiring pattern 30 to be narrow and a sufficient cross-sectional area to be ensured, thereby reducing the resistance of the wiring pattern 30.

[0031] Furthermore, it is preferable that the depth D1 of the groove 20 is greater than the width W1 of the groove 20. Thus, a narrow wiring pattern 30 can be formed and the cross-sectional area of ​​the wiring pattern 30 can be better ensured, so that the resistance of the wiring pattern 30 can be further reduced.

[0032] Below, use Figures 5A to 9C A method for manufacturing a flexible transparent wiring substrate 100 of the present embodiment (hereinafter, sometimes referred to as the present method) is described. The present method sequentially performs the following steps: a step of preparing a laminate 150 having a base substrate 10 and a protective layer 60; a step of forming a pattern of grooves 20 on the base substrate 10; a step of forming a wiring pattern 30; and a step of peeling the protective layer 60 from the base substrate 10.

[0033] First, if Figure 5A As shown, in the step of preparing the laminate 150, 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 heating and pressing using a film laminator or the like. As the film laminator, for example, a vacuum laminator (not shown) is preferably used. In this way, the presence of air between the base substrate 10 and the protective layer 60 can be suppressed, and the base substrate 10 and the protective layer 60 can be brought into close contact with each other in a good manner.

[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 the base substrate 10. When made of a material different from the base substrate 10, the protective layer 60 is preferably made of a resin material having a high absorbance to the wavelength of the laser 200 described later.

[0035] Furthermore, the protective layer 60 has, for example, an easily removable adhesive layer (not shown), and the protective layer 60 is releasably attached to the base substrate 10 via the adhesive layer. Here, the “easy peelability” of the adhesive layer is not limited, and it only needs to be a property that allows the protective layer 60 to be peeled from the base substrate 10 by physical treatment (for example, physical force load) after the wiring constituent material 32 is printed or dried. Such an easily releasable adhesive is not particularly limited, and for example, acrylic, rubber, and polyurethane adhesives can be used.

[0036] Then, if Figure 5B As shown, in the step of forming the pattern of the grooves 20 , the base substrate 10 is irradiated with the laser 200 through the protective layer 60 of the laminate 150 , thereby forming the pattern of the grooves 20 on the base substrate 10 . In the case of the present embodiment, a through hole 62 is formed in the protective layer 60 by a process of forming a pattern of the groove 20, and a groove 20 connected to the through hole 62 is formed in the base substrate 10. In more detail, by irradiating the laser 200, a laser-processed groove 160 is formed in the laminate 150, and the laser-processed groove 160 is formed in a V-shape whose width becomes narrower toward the depth direction. Moreover, in the laser-processed groove 160, with the boundary surface between the base substrate 10 and the protective layer 60 as a reference, the portion on the irradiation surface 151 side (the upper portion in the present embodiment) constitutes the through hole 62 of the protective layer 60, and the portion on the opposite side of the irradiation surface 151 side (the lower portion in the present embodiment) constitutes the groove 20 of the base substrate 10. Therefore, the width W1 (refer to Figure 3A and Figure 3B ) is greater than the width W2 of the through hole 62 (refer to Fig. 8A) is smaller. Therefore, compared with the case where the groove 20 is formed by irradiating the laser 200 directly (not via the protective layer 60) onto the base substrate 10, a groove 20 having a narrower width can be formed, and further a wiring pattern 30 having a narrower width can be formed. Furthermore, for example, a groove 20 having a width W1 smaller than the beam diameter (diameter R1 of the laser 200) of the laser processing device used can be easily formed. Furthermore, in this method, by adjusting the thickness of the protective layer 60 , that is, 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 formed groove 20 can also be adjusted.

[0037] In addition, in the present method, the processing conditions of the laser 200 are preferably set so that the depth D1 of the formed groove 20 is smaller than the thickness dimension of the base substrate 10, and the depth D1 of the formed groove 20 is approximately constant regardless of the position of the groove 20 in the extension direction. The depth of the laser processed groove 160 (more specifically, the depth D1 of the groove 20) is preferably adjusted by scanning multiple times using the step and repeat function of the laser device (not shown). In this way, the depth of the laser processed groove 160 (the depth D1 of the groove 20) can be finely adjusted. Furthermore, when irradiating the laser 200, thermal damage to the base substrate 10 and the protective layer 60 can be further suppressed.

[0038] The width W1 of the formed groove 20 is, for example, 50 μm or less as described above. More specifically, in the present embodiment, as an example, the diameter R1 of the laser beam 200 is 18 μm. Also, the width W1 of the groove 20 is, for example, about 13 μm. However, in the present invention, in addition to forming the groove 20 with a width W1 of 50 μm or less on the base substrate 10, Fig. 9A As shown, a groove 25 having a width greater than the diameter R1 of the laser beam 200 (for example, 50 μm or more) may be formed in the base substrate 10. In this case, the wiring pattern 30 formed in the groove 25 is used as a connection terminal connected to a land portion or a substrate of an electronic device or an electronic component, for example. In addition, for example, the wiring pattern 30 (connection terminal) formed in the groove 25 may be partially subjected to electroplating processing, for example. like Fig. 9AAs shown, for example, the groove 25 is formed by irradiating the laser 200 in an overlapping manner in the surface direction of the base substrate 10. At this time, the irradiation unit (not shown) of the laser processing device may be relatively moved in the surface direction of the base substrate 10 while maintaining the state of irradiating the laser 200, or the operation of relatively moving the irradiation unit in the surface direction of the base substrate 10 and irradiating the laser 200 again may be repeated multiple times while temporarily stopping the irradiation of the laser 200. According to such a method, for example, by adjusting the moving distance of the irradiation unit of the laser processing device or the overlapping width ( Fig. 9A W4 shown in the figure, so that the width of the groove 25 can be adjusted to match the size of the connection pad portion or substrate of the connected electronic equipment or electronic component. Furthermore, by setting the overlap width W4 to be less than or equal to the diameter R1 of the laser beam 200 , the laser processed groove 160 (more specifically, the groove 25 ) formed in the stacked body 150 can be formed into a V-shaped shape whose width becomes narrower toward the depth direction. In addition, when the overlap width W4 is set to be less than the diameter R1 of the laser 200, the processing speed of the laser 200 in the groove depth direction is faster than when the groove 20 is formed. Therefore, when forming the groove 25, it is preferable to set the processing conditions of the laser 200 to be different from the processing conditions of the laser 200 when forming the groove 20.

[0039] Here, in the case of this method, as the laser 200 , for example, ultrashort pulse laser is used. Thus, even without using an exposure mask or the like, thermal damage to the base substrate 10 can be suppressed, and a narrow groove 20 can be easily formed. Therefore, the transparency of the base substrate 10 can be well maintained, and the deviation of the width W1 of the groove 20 can be suppressed. Furthermore, by the multiphoton absorption effect of the ultrashort pulse laser, even for a transparent base substrate 10, laser processing can be performed sequentially from the irradiation surface 151 to the bottom surface of the groove 20, so that the deviation (deviation in the extension direction) of the depth D1 of the groove 20 caused by adjusting the laser output can be suppressed. Therefore, the deviation of the 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 step of forming the wiring pattern 30 , the wiring constituent material 32 is filled into the groove 20 and dried to form the wiring pattern 30 . In more detail, Figure 5C As shown, the wiring constituent material 32 is supplied onto the protective layer 60, and the scraper 250 is moved along the upper surface of the protective layer 60 (by scraping) with the top end of the scraper 250 in contact with the upper surface of the protective layer 60, thereby filling the wiring constituent material 32 into the interior of the laser-processed groove 160 (through hole 62 and groove 20). Thus, even without using a screen printing plate (not shown), a wiring pattern 30 with a narrow width can be easily and well formed. In addition, in this case, the screen printing plate can also be repeatedly used as an area for temporarily holding the wiring constituent material 32 or allowing the wiring constituent material 32 to escape. More specifically, as the screen printing plate, a screen printing plate having an opening portion in a plan view is used, and the opening portion is larger than the area including the entire groove 20 in the base substrate 10 and smaller in size than the outer dimensions of the base substrate 10. Thus, the wiring constituent material 32 can be temporarily held on the outer peripheral edge portion of the opening portion of the screen printing plate, or the wiring constituent material 32 can be avoided on the outer peripheral edge portion of the opening portion of the screen printing plate. Furthermore, after the wiring constituent material 32 is scraped, the metal particles 32a of the wiring constituent material 32 and the binder resin residues are generated on the protective layer 60, but in the step of peeling off the protective layer 60 described later, these metal particles 32a and the binder resin residues are peeled off together with the protective layer 60. Therefore, it is possible to suppress the metal particles 32a of the wiring constituent material 32 and the binder resin from remaining on the wiring pattern 30 or the base substrate 10. Furthermore, when the wiring constituent material 32 including the metal particles 32a is filled into the laser processed groove 160, the base substrate 10 can be protected by the protective layer 60, so that the wiring pattern 30 can be formed while maintaining the transparency and appearance of the base substrate 10 well.

[0041] Here, the process of forming the wiring pattern 30 includes a drying process (heat treatment process) of the wiring constituent material 32 after filling the wiring constituent material 32. The wiring pattern 30 (wiring constituent material 32) is in a paste state in the stage after printing and before the drying process, and is heated in the drying process to become a dry state. In the case of the present embodiment, in the drying step, oven drying or a conveyor oven is used as an example. In more detail, Figure 8A to Figure 8C As shown in FIG. 1 , the wiring component material 32 filled in the laser processed groove 160 (through hole 62 and groove 20) shrinks in thickness as a whole due to drying, and becomes substantially accommodated in the groove 20. More specifically, the height position of the upper surface 35 of the wiring component material 32 is from Fig. 8A The status shown drops to Figure 8B and Figure 8C In the completely dried state, the upper surface 35 of the wiring constituent material 32 may be flush with the upper surface 10a (upper surface) of the base substrate 10 or may be located below the upper surface 10a. Here, as described above, it is preferable that the upper surface 35 of the wiring constituent material 32 is a concave surface that is recessed toward the center portion in the width direction. In the present embodiment, as an example, by setting the above-mentioned scraping 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 the above-mentioned concave surface. In addition, if Figures 9A to 9C As shown, in the case of the groove 25 having a width wider than the diameter R1 of the laser beam 200 , the wiring pattern 30 is formed by filling the wiring constituent material 32 in the same steps as the groove 20 .

[0042] Then, if Fig. 6A As shown, in the step of peeling the protective layer 60 , the protective layer 60 is peeled off from the base substrate 10 . 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 in the middle of the step of forming the wiring pattern 30 . More specifically, when the drying process is performed in the middle of the process of forming the wiring pattern 30, for example, the above-mentioned drying process includes a preliminary drying process and a complete drying process, and each process is performed in the order of the preliminary drying process, the process of peeling off the protective layer 60, and the complete drying process. In the preliminary drying step, the heating state is set to a low heating temperature and heating time to suppress the fluidity of the wiring constituent material 32, so that the wiring constituent material 32 is semi-dried (semi-cured). Then, after the protective layer 60 is peeled off, the wiring constituent material 32 is completely dried (completely cured) in the complete drying step. Thus, even when the heating temperature of the wiring constituent material 32 (the temperature at which the wiring constituent material 32 is completely dried and solidified) is high, it is possible to prevent the adhesive layer (not shown) of the protective layer 60 from being over-cured when the wiring constituent material 32 is heated in the step of forming the wiring pattern 30. Therefore, in the step of peeling off the protective layer 60, the protective layer 60 can be easily peeled off from the base substrate 10.

[0043] In addition, when the above-mentioned 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 carbon layer 41, carbon layer 41 is filled on upper surface 35 of semi-dried or completely dried wiring constituent material 32. Carbon layer 41 is in a paste state after filling and before heat treatment, and is heated by heat treatment to become dry. The heat treatment of the carbon layer 41 may be performed simultaneously with the wiring pattern 30 in the complete drying step of the wiring pattern 30 , or the drying step (heat treatment step) of the carbon layer 41 may be performed separately after the complete drying step. The carbon layer 41 may be formed by printing, for example, although the method of forming the carbon layer 41 is not particularly limited. Examples of the printing method include screen printing, inkjet printing, gravure printing, and offset printing.

[0044] In the case of the present embodiment, as an example, heating in the preliminary drying step is preferably performed at a temperature of 70° C. to 250° C., more preferably 80° C. to 200° C. for about 5 to 10 minutes. Furthermore, 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 according to the materials of the wiring constituent material 32 and the base substrate 10 .

[0045] Here, in the case of this embodiment, it is preferred that Fig. 8A and Figure 8B As shown, the inclination angle of the side wall of the through hole 62 of the protective layer 60 is larger than the inclination angle of the side wall of the groove 20 of the base substrate 10 . According to such a structure, during the drying process, when the wiring constituent material 32 filled in the laser processed groove 160 (through hole 62 and groove 20) shrinks, a part of the wiring constituent material 32 can smoothly slide down into the groove 20 along the through hole 62. Therefore, in the dry state, the entire wiring constituent material 32 can be well accommodated in the groove 20. However, the present invention is not limited to this example, and the inclination angle of the side wall of the groove 20 of the base substrate 10 may be larger than the inclination angle of the side wall of the through hole 62 of the protective layer 60, or the inclination angle of the side wall of the groove 20 of the base substrate 10 and the inclination angle of the side wall of the through hole 62 of the protective layer 60 may be the same as each other.

[0046] Then, for example Figure 6B As shown, the present method carries out the step of attaching the insulating cover 50 to the upper surface 10a of the base substrate 10. As an example, the insulating cover 50 and the base substrate 10 are welded to each other by heating and pressing using a film laminator or the like, similarly to the protective layer 60. Thus, the base substrate 10 and the wiring pattern 30 can be well protected by the insulating cover 50 . However, in the present invention, the method does not necessarily need to include the step of disposing the insulating cover 50 on the upper surface 10 a of the base substrate 10 . That is, the flexible transparent wiring substrate 100 may not include the insulating cover 50 .

[0047] Here, in the case of this embodiment, if Figure 4B As shown, for example, there is a scratch 39 on the side 38a of the upper portion 34 of the wiring component material 32, and there is no scratch 39 on the side 38b of the lower portion 36 of the wiring component material 32. Figure 4B , the shape of the scratch 39 is schematically illustrated. Thus, at least a portion of the side surface 38a of the upper portion 34 of the wiring constituent material 32 can be anchored to the insulating cover 50. Therefore, the peeling resistance of the insulating cover 50 with respect to the base substrate 10 can be improved.

[0048] Thus, the method includes: a process of preparing a laminate, wherein the laminate has a transparent, flexible and insulating base substrate 10, and a protective layer 60 that is removably attached to the upper surface 10a of the base substrate 10; a process of forming a pattern of grooves 20 on the base substrate 10 by irradiating the base substrate 10 with a laser 200 through the protective layer 60 of the laminate; a process of filling the grooves 20 with a wiring material 32 and drying it to form a wiring pattern 30; and a process of peeling off the protective layer 60 from the base substrate 10. Furthermore, in the step of forming the pattern of the groove 20 , the groove 20 is formed into a V-shaped shape whose width becomes narrower toward the depth direction.

[0049] According to such a method, it is possible to easily form a wiring pattern 30 having a narrow width. As a result, the formation area of ​​the wiring pattern 30 in the base substrate 10 can be kept to a minimum, so that the transparency, elasticity, and bending resistance of the base substrate 10 can be suppressed from being impaired. That is, according to this embodiment, it is possible to achieve good transparency, elasticity, and bending resistance of the flexible transparent wiring substrate 100. In addition, compared with the manufacturing method of the flexible transparent wiring substrate using the usual screen printing method or inkjet method, according to the present method, no jigs such as a screen printing plate and an exposure mask are required, and the flexible transparent wiring substrate 100 can be manufactured using only a film laminator, a laser processing device, a screen printer, and a drying device. That is, the number of devices and jigs required for manufacturing the flexible transparent wiring substrate 100 can be reduced, so the flexible transparent wiring substrate 100 can be manufactured with higher productivity. Furthermore, compared with the manufacturing method of the flexible transparent wiring substrate using the conventional subtractive method, additive method, semi-additive method, etc., according to the present method, the wiring pattern 30 can be formed without using chemicals and water, so it is possible to suppress the generation of waste liquid accompanying the formation of the wiring pattern 30. Furthermore, since the temperature management of the waste liquid is not required, the energy consumed in the manufacturing of the flexible transparent wiring substrate 100 can be well reduced, and the load on the environment can be reduced.

[0050] Here, in Figure 10A to Figure 12An enlarged photograph of the flexible transparent wiring substrate 100 actually obtained by the above-mentioned method for manufacturing the flexible transparent wiring substrate 100 is shown. Figure 10A to Figure 12 An image obtained by photographing a cross section perpendicular to the extending direction of the groove 20 is shown. As described above, in this method, the base substrate 10 is irradiated with the laser 200 through the protective layer 60 of the laminate 150, thereby forming a pattern of the grooves 20 on the base substrate 10. Fig. 10A As shown in FIG. 1 , among the base substrate 10 and the protective layer 60, first, a through hole 62 is formed in the protective layer 60. Next, as shown in FIG. Fig. 10B and Fig. 10C As shown in FIG. 1 , a groove 20 is gradually formed in the base substrate 10 by laser 200. Then, as shown in FIG. Fig. 10D As shown, a laser processed groove 160 is formed in the stack 150, and the laser processed groove 160 is formed in a V-shape with a width narrowing toward the depth direction, and further a groove 20 is formed in the base substrate 10, and the groove 20 is formed in a V-shape with a width narrowing toward the depth direction. Thus, as described above, compared with the case where the groove 20 is formed by irradiating the base substrate 10 with the laser 200 directly (not via the protective layer 60 ), a narrower groove 20 can be formed, and thus a narrower wiring pattern 30 can be formed. also, Fig.11 The wiring pattern 30 is formed by filling the wiring constituent material 32 into the groove 20 thus obtained and drying the wiring constituent material 32 , and the protective layer 60 is peeled off from the base substrate 10 . like Fig.11 As shown, the upper surface 35 of the wiring constituent material 32 is a concave surface that is recessed toward the center in the width direction. This makes it easy to form layers such as the carbon layer 41 other than the wiring constituent material 32 in the groove 20 as described above (in Fig.11 Not formed in the state shown). However, in the present invention, it is also possible to Fig.11 As shown, it is not necessary to form a layer other than the wiring constituent material 32 such as the carbon layer 41 on the upper surface 35 of the wiring constituent material 32 which is a concave surface in the center in the width direction. In this case, for example, the insulating cover 50 may directly cover the wiring constituent material 32. also, Fig.12 FIG. 1 shows a state where the 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 substrate 10 . like Fig.12 As shown, the height position of the upper surface 35 of the wiring constituent material 32 is lower than the height position of the opening 21 of the groove 20 . Thus, as described above, the opening 21 of the groove 20 is closed by the carbon layer 41, so that ion migration in the wiring constituent material 32 in the groove 20 can be suppressed. In addition, the height position of the upper surface 35 of the wiring constituent material 32 is lower than the height position of the opening 21 of the groove 20, so that the carbon layer 41 can be suppressed from protruding from the groove 20, and a carbon layer 41 of sufficient thickness can be formed on the wiring constituent material 32.

[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 may be employed.

[0052] The above-mentioned embodiments include the following technical concepts. (1) A flexible transparent wiring substrate comprising a base substrate and wiring, the base substrate being transparent, flexible and insulating, a groove being formed on an upper surface of the base substrate, the wiring being formed of a wiring constituent material filled in the groove, and the groove being formed in a V-shape whose width becomes narrower toward a depth direction. (2) In the flexible transparent wiring substrate according to (1), the upper surface of the wiring constituent material is a concave surface that is recessed toward the center in the width direction of the wiring constituent material. (3) The flexible transparent wiring substrate according to (1) or (2), wherein the upper side surface of the wiring constituent material has scratches, and the lower side surface of the wiring constituent material does not have the scratches. (4) The flexible transparent wiring substrate according to (1) or (2) further comprises a carbon layer, wherein the height position of the upper surface of the wiring constituent material is lower than the height position of the opening of the groove, and the carbon layer is formed on the wiring constituent material and in the groove. (5) The flexible transparent wiring substrate according to (1) or (2), wherein the wiring is opaque, and in a plan view, an area of ​​a transparent region where the wiring is not formed is larger than an area where the wiring is formed. (6) In the flexible transparent wiring substrate according to (1) or (2), the depth of the groove is smaller than the thickness of the base substrate. (7) In the flexible transparent wiring substrate according to (1) or (2), the width of the groove is 50 μm or less. (8) In the flexible transparent wiring substrate according to (1) or (2), the depth of the groove is 80% or more of the width of the groove. (9) In the flexible transparent wiring substrate according to (8), the depth of the groove is greater than the width of the groove. (10) In the flexible transparent wiring substrate according to any one of (1) to (9), the wiring constituent material has flexibility that allows it to follow the bending deformation of the base substrate. (11) The flexible transparent wiring substrate according to any one of (1) to (10), further comprising an insulating cover formed to cover the upper surface of the base substrate and the wiring. (12) A method for manufacturing a flexible transparent wiring substrate, comprising: preparing a laminate having a transparent, flexible and insulating base substrate, and a protective layer removably attached to the upper surface of the base substrate; irradiating the base substrate with a laser through the protective layer of the laminate, thereby forming a groove in the base substrate; filling the groove with a wiring constituent material and drying it to form a wiring; and peeling off the protective layer from the base substrate to form the groove into a V-shape whose width becomes narrower toward the depth direction. (13) The method for manufacturing a flexible transparent wiring substrate according to (12), wherein an ultrashort pulse laser is used as the laser. (14) According to the manufacturing method of the flexible transparent wiring substrate described in (12) or (13), a through hole is formed in the protective layer by forming the groove, and the groove connected to the through hole is formed in the base substrate, and the inclination angle of the side wall of the through hole is larger than the inclination angle of the side wall of the groove. The detailed description has been given for the purpose of example and illustration. In light of the above teachings, many variations and changes are possible. The detailed description is not exhaustive or intended to limit the subject matter described herein. Although the subject matter has been described in words with specific structural features and / or method processes, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or specific processes described. More specifically, the specific features and specific processes are described as examples of implementing the claims.

Claims

1. A flexible transparent wiring substrate, characterized in that: A base substrate and wiring are provided. The base substrate is transparent, flexible and insulating. A groove is formed on the upper surface of the base substrate, The wiring is formed of a wiring constituent material filled in the groove, The groove is formed in a V-shape whose width becomes narrower toward the depth direction.

2. The flexible transparent wiring substrate according to claim 1, characterized in that: The upper surface of the wiring constituent material is a concave surface that is recessed toward the center portion in the width direction of the wiring constituent material.

3. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The upper side surface of the wiring constituent material has scratches, while the lower side surface of the wiring constituent material does not have the scratches.

4. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: It also has a carbon layer. 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 carbon layer is formed on the wiring constituent material and in the groove.

5. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The wiring is not transparent. In a plan view, the area of ​​the transparent region where the wiring is not formed is larger than the area of ​​the opaque region where the wiring is formed.

6. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The depth of the groove is less than the thickness of the base substrate.

7. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The width of the groove is 50 μm or less.

8. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The depth of the groove is greater than or equal to 80% of the width of the groove.

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

10. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: The wiring constituent material has flexibility to follow the bending deformation of the base substrate.

11. The flexible transparent wiring substrate according to claim 1 or 2, characterized in that: It also has an insulating cover. The insulating cover is formed to cover the upper surface of the base substrate and the wiring.

12. A method for manufacturing a flexible transparent wiring substrate, characterized in that: include: preparing a laminate comprising a transparent, flexible and insulating base substrate and a protective layer releasably attached to an upper surface of the base substrate; forming a groove in the base substrate by irradiating the base substrate with laser light through the protective layer of the laminate; filling the groove with a wiring constituent material and drying the material to form wiring; and peeling the protective layer from the base substrate, The groove is formed into a V-shape whose width becomes narrower toward the depth direction.

13. The method for manufacturing a flexible transparent wiring substrate according to claim 12, wherein: As the laser light, ultrashort pulse laser light is used.

14. The method for manufacturing a flexible transparent wiring substrate according to claim 12 or 13, characterized in that: By forming the groove, a through hole is formed in the protective layer, and the groove communicating with the through hole is formed in the base substrate. The inclination angle of the side wall of the through hole is larger than the inclination angle of the side wall of the groove.

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