Conductive film

Abstract

The present invention comprises: a light-transmitting substrate (11); main wiring (12) formed from first thin wire conductors provided to the substrate (11); mounting pads (13) formed from first conductors provided to the substrate (11); inspection pads (14) formed from second thin wire conductors provided to the substrate (11); and external connection pads (15) formed from second conductors provided to the substrate (11). The mounting pads (13) and the external connection pads (15) are electrically connected via the main wiring (12), and the mounting pads (13) and the inspection pads (14) are electrically connected via first connection wiring (16).

Description

Conductive Film

[0001] The present disclosure relates to a conductive film.

[0002] In electrical devices, a wiring board in which metal wires are formed on a substrate is used. The wiring board is used as a touch sensor board provided with sensor electrodes, or as a mounting board on which electronic components such as LED (Light-Emitting Diode) elements or circuit elements are mounted. It is known that fine metal wires are formed as wirings on these wiring boards.

[0003] Since the fine metal wires formed on the wiring board have a line width of 100 μm or less, they are difficult to be recognized by the naked eye of a person. Therefore, although the wiring board is formed with wirings by metal wires having light-shielding properties, it is felt like a transparent film. That is, a wiring board formed with fine metal wires is a transparent conductive film that appears transparent.

[0004] For example, a transparent conductive film is used for a display device. In this case, electronic components such as LED elements or circuit elements are mounted on the transparent conductive film. In order to mount an electronic component on the transparent conductive film, the transparent conductive film includes mounting pads connected to fine metal wires.

[0005] In a transparent conductive film having fine metal wires, the electrical connection state (presence or absence of disconnection) of the fine metal wires may be confirmed using an inspection probe. In this case, in a transparent conductive film having mounting pads, in order to guarantee an electrical connection to the mounting pads, which are the ends of the circuit, the inspection probe is brought into contact.

[0006] However, when the inspection probe is brought into contact with the mounting pad, the mounting pad may be recessed due to the pressing by the inspection probe, and a step may occur in the mounting pad. As a result, the adhesion of the electronic component may decrease, the electronic component may be tilted and mounted on the mounting pad, or the electronic component may not contact the mounting pad.

[0007] Therefore, in order to check the electrical connection state of fine metal wires without bringing the inspection probe into contact with the mounting pads, it is conceivable to form inspection pads connected to fine metal wires. For example, as a wiring board having inspection pads, Patent Document 1 discloses a conductive film for a touch panel comprising a transparent resin substrate, a plurality of detection electrodes having a mesh pattern made of fine metal wires, lead wires connected to the detection electrodes, peripheral wires not connected to the detection electrodes, external connection terminals connected to the lead wires and peripheral wires, and an inspection pad formed at one end of the peripheral wires.

[0008] International Publication No. 2016 / 035810

[0009] However, the inspection pad described in Patent Document 1 requires a relatively large surface area to facilitate contact with the inspection probe, and is therefore visible to the naked eye. Consequently, when the inspection pad is provided on a transparent conductive film, the visibility of the transparent conductive film is impaired.

[0010] This disclosure is made to solve these problems and aims to provide a conductive film that allows the electrical connection status of wiring to be confirmed by an inspection probe without impairing visibility.

[0011] To achieve the above objective, one embodiment of a conductive film according to the present disclosure comprises a light-transmitting substrate, a main wiring formed of a first fine wire conductor provided on the substrate, a mounting pad formed of the first conductor provided on the substrate, an inspection pad formed of a second fine wire conductor provided on the substrate, and an external connection pad formed of the second conductor provided on the substrate, wherein the mounting pad and the external connection pad are electrically connected via the main wiring, and the mounting pad and the inspection pad are electrically connected via a first connecting wiring.

[0012] According to this disclosure, the electrical connection status of the wiring can be confirmed using an inspection probe without impairing visibility.

[0013] Figure 1 is a schematic diagram showing a conductive film according to an embodiment. Figure 2 is an enlarged view of the region (II) enclosed by the dashed line in Figure 1. Figure 3 is a partial cross-sectional view of the conductive film according to the embodiment when cut along the line A-A in Figure 2. Figure 4 is a diagram showing an example of the top view shape of a mounting pad.

[0014] The embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below are all specific examples of this disclosure. Therefore, the numerical values, shapes, materials, components, arrangement and connection configurations of components, as well as the processes (steps) and their order, shown in the following embodiments are examples and are not intended to limit this disclosure. Accordingly, any components in the following embodiments that are not described in the independent claims representing the highest-level concepts of this disclosure will be described as optional components.

[0015] Please note that each figure is a schematic diagram and not necessarily a strictly accurate representation. Therefore, the scale and other aspects may not necessarily be consistent across all figures. In addition, the same reference numerals are used for substantially identical components in each figure, and redundant explanations are omitted or simplified. Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the absolute upward (vertically upward) and downward (vertically downward) directions in spatial perception.

[0016] (Embodiment) First, the configuration of the conductive film 1 according to the embodiment will be explained using Figure 1. Figure 1 is a schematic diagram showing the conductive film 1 according to the embodiment. Note that the hatching drawn on the mounting pad 13 shown in Figure 1 is a pattern added for emphasis in the explanation and does not represent a cross-section. The same applies to the following drawings.

[0017] As shown in Figure 1, the conductive film 1 is a wiring substrate on which metal wires of a predetermined shape are formed. In this embodiment, the conductive film 1 is a flexible film-like wiring substrate. Furthermore, the conductive film 1 is a light-transmitting wiring substrate. In this embodiment, the conductive film 1 is a transparent film-like wiring substrate. In other words, the conductive film 1 is a transparent conductive film that is transparent enough to allow the other side to be seen through.

[0018] A wiring board 110 is connected to the conductive film 1. The wiring board 110 may be a wiring board having only wiring functions, with only metal wires formed on it, or it may be a COF (Chip on Film) on which semiconductor chips such as driver ICs are mounted.

[0019] The conductive film 1 has an effective region 21 (active region), which is the area enclosed by the dashed line, and an inactive region 22 (inactive region) located outside the effective region 21. The effective region 21 is the area through which one can see (the view area seen by the user), and the inactive region 22 is the area through which one cannot see (the non-view area not seen by the user). For example, the effective region 21 is a rectangular region. The inactive region 22 is a frame-like region (frame region) surrounding the effective region 21. The inactive region 22 may not exist. The inactive region 22 is a peripheral region located around the conductive film 1. The wiring board 110 is connected to the inactive region 22. For example, the conductive film 1 and the wiring board 110 are joined in the inactive region 22 by a conductive bonding member such as an anisotropic conductive film (ACF) or solder.

[0020] The conductive film 1 comprises a substrate 11, main wiring 12, mounting pads 13, inspection pads 14, and external connection pads 15.

[0021] The substrate 11 is a substrate that serves as the base film for the conductive film 1. Specifically, it is a sheet-shaped film substrate.

[0022] In this embodiment, the substrate 11 is a transparent substrate that is translucent to visible light. Specifically, the substrate 11 is a substrate that is transparent enough to allow the other side to be seen through, in other words, a transparent substrate with high transmittance to the extent that the other side can be seen through.

[0023] The substrate 11 is made of a resin material. In this embodiment, the substrate 11 is made of a translucent resin material. Specifically, the substrate 11 is made of a transparent resin material. The substrate 11 is an insulating substrate. Therefore, the substrate 11 is made of a transparent insulating resin material. The substrate 11 is a flat plate with a constant thickness. The top view shape of the substrate 11 is, for example, rectangular, but is not limited to this.

[0024] As the translucent resin material constituting the substrate 11, for example, polyethylene terephthalate (PET) resin, polyimide (PI) resin, polyethylene naphthalate (PEN) resin, cycloolefin resin, polycarbonate resin, or acrylic resin can be used. In this embodiment, the substrate 11 is a transparent PET film made of PET. A transparent glass substrate may also be used as the substrate 11.

[0025] The main wiring 12 is a wiring formed of first fine wire conductors provided on the substrate 11. Specifically, the main wiring 12 is a wiring formed of a plurality of first fine wire conductors in the effective region 21. The main wiring 12 is a wiring in which a plurality of first fine wire conductors are formed in a predetermined pattern. The predetermined pattern is, for example, a pattern (mesh) in which a plurality of first fine wire conductors intersect in a mesh-like manner. The angles at which the plurality of first fine wire conductors intersect in a mesh-like manner may be orthogonal or not. Also, the predetermined pattern may not be a mesh-like manner. For example, each of the plurality of first fine wire conductors may be provided parallel to each other.

[0026] The first fine conductors forming the main wiring 12 are fine metal wires with a width on the order of micrometers. For example, the width of the first fine conductor is 100 μm or less, preferably 50 μm or less. In this embodiment, the width of the first fine conductor is 2 μm. As a result, the main wiring 12 formed by multiple first fine conductors is difficult to perceive with the naked eye.

[0027] In Figure 1, the main wiring 12 is only shown within the effective area 21, but in reality, it is also provided within the inactive area 22. The line width of the main wiring 12 may change within the inactive area 22. Since the main wiring 12 in the inactive area 22 is not visible to the user, for example, the line width of the main wiring 12 in the inactive area 22 may be 100 μm or more.

[0028] The mounting pad 13 and the external connection pad 15 are electrically connected via the main wiring 12. Figure 1 is a schematic representation of the electrical connection relationship between the mounting pad 13 and the external connection pad 15 via the main wiring 12, using dashed arrows.

[0029] The mounting pad 13 is a pad formed of a first conductor provided on the substrate 11. Specifically, the mounting pad 13 is a solid film pad formed of a film-like first conductor in the effective region 21. Because the mounting pad 13 is film-like, it is easier to bring electronic components into contact with the mounting pad 13, thereby improving the reliability of the connection between the mounting pad 13 and the electronic components. Electronic components such as LED elements or circuit elements are mounted on the mounting pad 13. The conductive film 1 with LED elements or the like mounted on the mounting pad 13 can be used as a display device.

[0030] Two adjacent mounting pads 13 are used as a pair of mounting pads 13a. Specifically, two terminals extending from one electronic component are connected to the pair of mounting pads 13a, respectively. One of the two adjacent mounting pads 13 is connected to the anode terminal of the electronic component, and the other of the two adjacent mounting pads 13 is connected to the cathode terminal of the electronic component. In this embodiment, the configuration consists of two mounting pads in a pair of mounting pads 13a, but it may also consist of three or more mounting pads.

[0031] The inspection pad 14 is a pad formed of a second fine wire conductor provided on the substrate 11. Specifically, the inspection pad 14 is a pad formed of multiple second fine wire conductors in the effective area 21. By bringing the inspection pad 14 into contact with the inspection probe, the electrical connection relationship between the mounting pad 13 and the external connection pad 15 via the main wiring 12 can be confirmed. The electrical connection relationship between the inspection pad 14 and the mounting pad 13, etc., will be described later.

[0032] The second fine wire conductor forming the inspection pad 14 is a fine metal wire with a wire width on the order of micrometers. For example, the wire width of the second fine wire conductor is 100 μm or less, preferably 50 μm or less. In this embodiment, the wire width of the second fine wire conductor is 2 μm. As a result, the inspection pad 14 formed of multiple second fine wire conductors is difficult to recognize with the naked eye.

[0033] Here, the inspection pad 14 may be substituted by extending the first connecting wiring 16 (described later) into a linear shape, or by extending the first connecting wiring 16 and making the distal end of the first connecting wiring 16 from the mounting pad 13 wider in a strip shape.

[0034] The external connection pad 15 is a second conductor provided on the substrate 11. Specifically, the external connection pad 15 is a pad formed of a film-like second conductor in the inactive region 22. The external connection pad 15 is electrically connected to the wiring board 110.

[0035] The conductor density per unit area of ​​the external connection pad 15 is greater than that of the inspection pad 14. In other words, the aperture ratio per unit area of ​​the external connection pad 15 is smaller than that of the inspection pad 14. As a result, the connection reliability between the external connection pad 15 and the inspection probe is higher than that between the inspection pad 14 and the inspection probe.

[0036] The first fine wire conductor forming the main wiring 12, the first conductor forming the mounting pad 13, the second fine wire conductor forming the inspection pad 14, and the second conductor forming the external connection pad 15 are all made of the same metal material. In other words, the first fine wire conductor, the first conductor, the second fine wire conductor, and the second conductor are all made of the same metal material. For example, the first fine wire conductor, the first conductor, the second fine wire conductor, and the second conductor are copper wiring with copper as the main material. The first fine wire conductor, the first conductor, the second fine wire conductor, and the second conductor may also be made of a laminated film in which multiple metal layers are stacked. However, the first fine wire conductor, the first conductor, the second fine wire conductor, and the second conductor may each be made of different metal materials.

[0037] Furthermore, the conductive film 1 has a first connecting wire 16. The mounting pad 13 and the inspection pad 14 are electrically connected via the first connecting wire 16. Note that the first connecting wire 16 may also be the main wire 12.

[0038] The first connecting wire 16 is a fine metal wire with a wire width on the order of micrometers. For example, the wire width of the first connecting wire 16 is 100 μm or less, preferably 50 μm or less. In this embodiment, the wire width of the first connecting wire 16 is 2 μm. As a result, the first connecting wire 16 is difficult to perceive with the naked eye.

[0039] The first connecting wiring 16 may be made of the same metal material as the first thin wire conductors that form the main wiring 12, or it may be made of a different metal material. For example, the first connecting wiring 16 is copper wiring. Alternatively, the first connecting wiring 16 may be made of a laminated film in which multiple metal layers are stacked.

[0040] The electronic component mounting area 100 is an area indicated by a dashed line drawn overlapping a pair of mounting pads 13a. The electronic component mounting area 100 is an area for mounting electronic components such as LED elements or circuit elements on a pair of mounting pads 13a.

[0041] Figure 2 is an enlarged view of the area (II) enclosed by the dashed line in Figure 1. Figure 2 represents electrical connection relationships using areas separated by dashed lines (same connection area) and arrows indicated by dashed lines. The hatching on the second connecting wiring 17 shown in Figure 2, like the hatching on the mounting pad 13 in Figure 1, is a pattern added for explanatory emphasis and does not represent a cross-section. The same applies to the following drawings.

[0042] As shown in Figure 2, the main wiring 12 has intersections where multiple first thin wire conductors intersect. The multiple first thin wire conductors are integrated at the intersections. For example, the main wiring 12 has intersections 12a and 12b. Here, intersections 12a and 12b are shown for illustrative purposes only, and intersections similarly exist at other locations where the first thin wire conductors intersect. The length of the first thin wire conductor connecting intersection 12a and intersection 12b is longer than the length of the first connecting wiring 16 and the length of the second connecting wiring 17, which will be described later.

[0043] The top view shape of the mounting pad 13 is rectangular, but is not limited to this. For example, the top view shape of the mounting pad 13 may be trapezoidal or circular.

[0044] The inspection pad 14 is a pad formed by a plurality of second fine conductors in a predetermined pattern. The predetermined pattern may be a mesh shape in which a plurality of second fine conductors intersect in a mesh pattern, or an incomplete mesh shape in which a part of the plurality of second fine conductors intersecting in a mesh pattern is interrupted. Specifically, the inspection pad 14 has, as the second fine conductors, a first wiring 14a, a second wiring 14b, a third wiring 14c, a fourth wiring 14d, a fifth wiring 14e, and a sixth wiring 14f. The first wiring 14a intersects the third wiring 14c, the second wiring 14b, and the fourth wiring 14d in this order from one end of the first wiring 14a. Further, the second wiring 14b intersects the fifth wiring 14e, the first wiring 14a, and the sixth wiring 14f in this order from one end of the second wiring 14b. Note that the third wiring 14c may or may not intersect the fifth wiring 14e and the sixth wiring 14f. Also, the fourth wiring 14d may or may not intersect the fifth wiring 14e and the sixth wiring 14f. The angle at which the plurality of second fine conductors intersect in a mesh pattern may or may not be orthogonal. Further, the wiring lengths of the first wiring 14a, the second wiring 14b, the third wiring 14c, the fourth wiring 14d, the fifth wiring 14e, and the sixth wiring 14f are not limited to the lengths as shown in FIG. 2. For example, the lengths of the third wiring 14c, the fourth wiring 14d, the fifth wiring 14e, and the sixth wiring 14f may be the same as or longer than the lengths of the first wiring 14a and the second wiring 14b. With this configuration, the inspection pad 14 has a plurality of intersection points, so that it becomes easier to bring the inspection pad 14 into contact with the inspection probe. As a result, it becomes easier to further confirm the electrical connection state of the main wiring 12.

[0045] Also, the first wiring 14a is connected to the first connection wiring 16. As shown in FIG. 2, the connection location between the first wiring 14a and the first connection wiring 16 is an end portion of the first wiring 14a close to the intersection of the first wiring 14a and the third wiring 14c and the intersection of the first wiring 14a and the third wiring 14c. Note that the connection location between the first wiring 14a and the first connection wiring 16 is an example, and even other connection locations are within the scope of the present embodiment.

[0046] Furthermore, the aperture ratio per unit area of the inspection pad 14 is smaller than the aperture ratio per unit area of the main wiring 12. In other words, the conductor occupation ratio per unit area of the second fine wire conductor forming the inspection pad 14 is higher than the conductor occupation ratio per unit area of the first fine wire conductor forming the main wiring 12. With this configuration, the contact resistance between the inspection pad 14 and the inspection probe can be reduced. Thereby, the accuracy of the inspection for confirming the electrical connection state of the main wiring 12 can be improved.

[0047] Also, the line width and wiring interval of the plurality of first fine wire conductors forming the main wiring 12 may be larger or smaller than the line width and wiring interval of the plurality of second fine wire conductors forming the inspection pad 14. In order to improve the light transmittance of the conductive film 1, it is preferable to make the line width and wiring interval of the plurality of first fine wire conductors forming the main wiring 12 and the line width and wiring interval of the plurality of second fine wire conductors forming the inspection pad 14 the same.

[0048] The region showing the inspection pad 14 is the region surrounded by the broken line. That is, the shape of the region surrounded by the broken line forms the outermost shape of the inspection pad 14. Also, since the area forming the outermost shape of the inspection pad 14 is larger than the area forming the outermost shape of the mounting pad 13, the inspection pad 14 and the inspection probe can be stably contacted. Thereby, even if the inspection pad 14 is formed of the second fine wire conductor, the electrical connection state of the main wiring 12 can be confirmed by the inspection probe.

[0049] The position where the inspection pad 14 is arranged is not limited to the position shown in FIG. 2 as long as it is a position where the electrical connection relationship between the mounting pad 13 and the external connection pad 15 can be confirmed. Specifically, the position where the inspection pad 14 is arranged may be within the same connection region as the mounting pad 13 connected via the first connection wiring 16. Thereby, misjudgment regarding the electrical connection relationship between the mounting pad 13 and the external connection pad 15 can be prevented.

[0050] The first connecting wire 16 that electrically connects the mounting pad 13 and the test pad 14 is a wire composed of multiple wires. For example, the first connecting wire 16 is composed of two wires. With this configuration, even if one of the multiple first connecting wires 16 is disconnected, the mounting pad 13 and the test pad 14 remain electrically connected via the remaining first connecting wires 16. This makes it easier to further check the electrical connection status of the main wiring 12.

[0051] The main wiring 12 has a second connecting wiring 17. The main wiring 12 and the mounting pad 13 are electrically connected via the second connecting wiring 17. The second connecting wiring 17 is a wiring composed of multiple wires. For example, the second connecting wiring 17 is composed of two wires. With this configuration, even if one of the multiple second connecting wirings 17 is disconnected, the main wiring 12 and the mounting pad 13 remain electrically connected via the remaining second connecting wiring 17. This makes it easier to check the electrical connection status of the main wiring 12.

[0052] The second connecting wire 17 is a fine metal wire with a wire width on the order of micrometers. For example, the wire width of the second connecting wire 17 is 100 μm or less, preferably 50 μm or less. In this embodiment, the wire width of the second connecting wire 17 is 2 μm. As a result, the second connecting wire 17 is difficult to perceive with the naked eye.

[0053] The conductive film 1 includes a sub-wiring 18. The sub-wiring 18 is a wiring formed of third fine wire conductors provided on the substrate 11. Specifically, the sub-wiring 18 is a wiring formed of a plurality of third fine wire conductors in the effective region 21. The sub-wiring 18 is a wiring in which the third fine wire conductors are formed in a predetermined pattern. The predetermined pattern is, for example, a pattern (mesh) in which a plurality of third fine wire conductors intersect in a mesh-like manner. The angles at which the plurality of third fine wire conductors intersect may be orthogonal or not. Also, the predetermined pattern may not be a mesh. For example, each of the plurality of third fine wire conductors may be provided parallel to each other.

[0054] The sub-wiring 18 is not electrically connected to the main wiring 12, mounting pad 13, inspection pad 14, external connection pad 15, first connecting wiring 16, and second connecting wiring 17.

[0055] The wire width of the third fine conductor forming the sub-wiring 18 is 100 μm or less, and in this embodiment, it is 10 μm or less. As a result, the sub-wiring 18 formed of the third fine conductor is difficult to perceive with the naked eye.

[0056] By providing the sub-wiring 18 in the area where the main wiring 12 is not provided, the overall transmittance in the effective area 21 of the conductive film 1 becomes close to a similar value. This improves the visibility of the conductive film 1. In order to make the overall transmittance in the effective area 21 of the conductive film 1 even closer to a similar value, it is preferable to match the wire width and wiring spacing of the first thin wire conductor forming the main wiring 12 with the wire width and wiring spacing of the third thin wire conductor forming the sub-wiring 18.

[0057] The third fine wire conductor forming the sub-wiring 18 may be made of the same metal material as the first fine wire conductor forming the main wiring 12, or it may be made of a different metal material. For example, the third fine wire conductor is copper wiring. The third fine wire conductor may also be made of a laminated film in which multiple metal layers are stacked.

[0058] Figure 3 is a partial cross-sectional view of the conductive film 1 according to an embodiment when cut along the line A-A in Figure 2. Figure 3(a) is a partial cross-sectional view when the main wiring 12 is embedded in the substrate 11, and Figure 3(b) is a partial cross-sectional view when the main wiring 12 is formed on the substrate 11.

[0059] As shown in Figure 3(a), the main wiring 12 is embedded wiring embedded in the substrate 11. As an example of a method for manufacturing embedded wiring, a method using the imprint method will be briefly described. First, a thermoplastic resin layer is formed on a base substrate (for example, a PET substrate). Next, the temperature is increased to soften the resin layer, and a mold member (mold) that serves as a transfer plate is pressed onto the resin layer and removed from the resin layer. This creates a substrate 11 consisting of a base substrate and a resin layer having grooves. Next, a metal film is formed in the formed grooves by vapor deposition or sputtering, and the main wiring 12 is formed in the grooves of the substrate 11 by electroplating or electroless plating on the metal film. Although a method for manufacturing embedded wiring using thermoplastic resin by thermal imprint has been described, it is not limited to this, and a method for manufacturing embedded wiring using photocurable resin by photoimprint may also be used. In addition, the mounting pads 13, inspection pads 14, first connecting wiring 16, second connecting wiring 17, and sub-wiring 18 may be manufactured using the above method.

[0060] As shown in Figure 3(b), the main wiring 12 is wiring formed on the substrate 11. As an example of a manufacturing method, a method using photoresist will be briefly explained. First, a metal foil is placed on the substrate 11 and the substrate 11 and the metal foil are bonded together by heat pressing. Next, a photosensitive resist solution is used to protect only the metal foil in the circuit area. Then, the unnecessary parts of the metal foil are removed using an etching solution to form the main wiring 12. Although a method of manufacturing wiring using photoresist with a photosensitive resist solution has been explained, it is not limited to this. In addition, the mounting pads 13, inspection pads 14, first connecting wiring 16, second connecting wiring 17, and sub-wiring 18 may also be manufactured using the above method.

[0061] Figure 4 shows an example of the top view shape of the mounting pad 13. Figure 4(a) shows an example in which the mounting pad 13 has an opening 19, Figure 4(b) shows another example in which the mounting pad 13 has an opening 19, and Figure 4(c) shows yet another example in which the mounting pad 13 has an opening 19.

[0062] As shown in Figure 4(a), the mounting pad 13 has an opening 19 that penetrates the film-like conductor. For example, the opening 19 divides the mounting pad 13 into two parts. Each mounting pad 13 is connected to the second connecting wiring 17.

[0063] As shown in Figure 4(b), the mounting pad 13 has an opening 19 inside, which is formed of a film-like conductor.

[0064] As shown in Figure 4(c), the mounting pad 13 has a plurality of openings 19 inside, which are formed from a film-like conductor. For example, the mounting pad 13 has four openings 19 inside, which are formed from a film-like conductor.

[0065] As shown in Figures 4(a) to 4(c), the mounting pad 13 having the opening 19 has a smaller conductor occupied area and a smaller heat conduction area than the mounting pad 13 without the opening 19, thereby reducing the heat capacity of the mounting pad 13. Therefore, during reflow soldering when mounting electronic components onto the mounting pad 13, the temperature of the mounting pad 13 rises more easily, allowing the mounting pad 13 and the electronic components to be soldered together in a shorter time.

[0066] As described above, the conductive film 1 according to this embodiment comprises a light-transmitting substrate 11, a main wiring 12 formed of a first fine wire conductor provided on the substrate 11, a mounting pad 13 formed of the first conductor provided on the substrate 11, and an inspection pad 14 formed of a second fine wire conductor provided on the substrate 11. Furthermore, the area of ​​the outermost shape of the inspection pad 14 is larger than the area of ​​the outermost shape of the mounting pad 13.

[0067] As described above, in the conductive film 1 according to this embodiment, the inspection pad 14 is formed of a second fine wire conductor, making it difficult for the naked eye to perceive the inspection pad 14. For example, by forming the inspection pad 14 with a fine metal wire, it is possible to make the inspection pad 14 difficult for the naked eye to perceive. Therefore, even if the inspection pad 14 is present, it is possible to suppress any impairment of the visibility of the light-transmitting conductive film 1, which is composed of a light-transmitting substrate 11.

[0068] Furthermore, if the inspection pad 14 is formed from a second fine wire conductor, it may become difficult to stably bring the inspection pad 14 into contact with the inspection probe. However, in the conductive film 1 according to this embodiment, the area of ​​the outermost shape of the inspection pad 14 is larger than the area of ​​the outermost shape of the mounting pad 13, so that the inspection pad 14 and the inspection probe can be stably brought into contact. Therefore, even if the inspection pad 14 is formed from a second fine wire conductor, the electrical connection state of the main wiring 12 can be confirmed by the inspection probe.

[0069] Thus, according to the conductive film 1 of this embodiment, the electrical connection status of the wiring can be confirmed by an inspection probe without impairing visibility.

[0070] Furthermore, in the conductive film 1 according to this embodiment, the aperture ratio per unit area of ​​the inspection pad 14 is smaller than the aperture ratio per unit area of ​​the main wiring 12. In other words, the conductor occupancy rate per unit area of ​​the second fine wire conductor forming the inspection pad 14 is higher than the conductor occupancy rate per unit area of ​​the first fine wire conductor forming the main wiring 12.

[0071] This configuration reduces the contact resistance between the inspection pad 14 and the inspection probe. This improves the accuracy of inspections to check the electrical connection status of the wiring.

[0072] Furthermore, in the conductive film 1 according to this embodiment, the mounting pad 13 is in the form of a film.

[0073] This configuration makes it easier to bring electronic components into contact with the mounting pads 13, thereby improving the reliability of the connection between the mounting pads 13 and the electronic components.

[0074] Furthermore, in the conductive film 1 according to this embodiment, the mounting pad 13 has an opening 19.

[0075] This configuration allows the mounting pad 13 with the opening 19 to have a smaller conductor occupied area and a smaller heat conduction area than the mounting pad 13 without the opening 19, thereby reducing the heat capacity of the mounting pad 13. As a result, the temperature of the mounting pad 13 rises more easily during reflow soldering when mounting electronic components to the mounting pad 13, allowing the mounting pad 13 and the electronic components to be soldered together in a shorter time.

[0076] Furthermore, in the conductive film 1 according to this embodiment, the inspection pad 14 has a first wiring 14a, a second wiring 14b, a third wiring 14c, a fourth wiring 14d, a fifth wiring 14e, and a sixth wiring 14f as second thin wire conductors. The first wiring 14a intersects the third wiring 14c, the second wiring 14b, and the fourth wiring 14d in that order from one end of the first wiring 14a, and the second wiring 14b intersects the fifth wiring 14e, the first wiring 14a, and the sixth wiring 14f in that order from one end of the second wiring 14b. With this configuration, the inspection pad 14 has multiple intersection points, making it easier to bring the inspection pad 14 into contact with the inspection probe. This makes it even easier to confirm the electrical connection state of the wiring.

[0077] Furthermore, in the conductive film 1 according to this embodiment, the first connecting wire 16 is composed of multiple wires. With this configuration, even if one of the multiple first connecting wires 16 is broken, the mounting pad 13 and the inspection pad 14 are electrically connected via the remaining first connecting wires 16. This makes it possible to reliably confirm the electrical connection state of the wiring.

[0078] Furthermore, in the conductive film 1 according to this embodiment, the main wiring 12 and the mounting pad 13 are electrically connected via a second connecting wiring 17, and the second connecting wiring 17 is composed of multiple wires. With this configuration, even if one of the multiple second connecting wirings 17 is broken, the main wiring 12 and the mounting pad 13 remain electrically connected via the remaining second connecting wirings 17. This makes it possible to reliably confirm the electrical connection state of the wiring.

[0079] Furthermore, in the conductive film 1 according to this embodiment, a sub-wiring 18 formed of a third fine wire conductor is provided on the substrate 11, and the sub-wiring 18 is not electrically connected to the main wiring 12. With this configuration, the sub-wiring 18 is provided in the area where the main wiring 12 is not provided, and the overall transmittance in the effective area 21 of the conductive film 1 becomes close to that value. As a result, the visibility of the conductive film 1 is improved.

[0080] Furthermore, the overall light transmittance in the effective region 21 (light transmittance = transmitted light intensity / incident light intensity) should be 35% or more in the visible light region, and preferably 50% or more.

[0081] (Other variations) The conductive film relating to this disclosure has been described above based on embodiments, but this disclosure is not limited to the above embodiments.

[0082] For example, in the above embodiment, the conductive film 1 was used as a mounting substrate for mounting electronic components such as LED elements or circuit elements, but it is not limited to this. For example, the light-transmitting conductive film 1 may be used as a touch sensor substrate in a touch panel, as a connection substrate for electrically connecting electronic components, as an antenna substrate having wiring formed in a predetermined pattern as a pattern antenna such as a 5G antenna, or as a heater substrate using metal wires as heating elements.

[0083] Furthermore, this disclosure also includes forms obtained by applying various modifications to the above embodiments that a person skilled in the art could conceive, and forms realized by arbitrarily combining the components and functions of the embodiments without departing from the spirit of this disclosure. In addition, this disclosure also includes any combination of two or more claims from the multiple claims described in the claims of this application, provided that they are not technically contradictory. For example, if the cited claims described in the claims of this application are made into a multi-claim or multi-multi-claim so as to refer to all of the higher-level claims without technically contradictory, then all combinations of claims included in that multi-claim or multi-multi-claim are also included in this disclosure.

[0084] The conductive film relating to this disclosure can be used in various electrical devices, including transparent displays.

[0085] 1 Conductive film 11 Substrate 12 Main wiring 12a, 12b Intersection 13 Mounting pad 13a A pair of mounting pads 14 Test pad 14a First wiring 14b Second wiring 14c Third wiring 14d Fourth wiring 14e Fifth wiring 14f Sixth wiring 15 External connection pad 16 First connecting wiring 17 Second connecting wiring 18 Sub-wiring 19 Opening 21 Effective area 22 Ineffective area 100 Electronic component mounting area 110 Wiring board

Claims

1. A conductive film comprising: a light-transmitting substrate; a main wiring formed of a first fine wire conductor provided on the substrate; a mounting pad formed of the first conductor provided on the substrate; an inspection pad formed of a second fine wire conductor provided on the substrate; and an external connection pad formed of the second conductor provided on the substrate, wherein the mounting pad and the external connection pad are electrically connected via the main wiring, and the mounting pad and the inspection pad are electrically connected via a first connecting wiring.

2. The conductive film according to claim 1, wherein the area of ​​the outermost shape of the inspection pad is larger than the area of ​​the outermost shape of the mounting pad.

3. The conductive film according to claim 1, wherein the conductor occupancy rate per unit area of ​​the inspection pad is smaller than the conductor occupancy rate per unit area of ​​the main wiring.

4. The conductive film according to claim 1, wherein the mounting pad is in the form of a film.

5. The conductive film according to claim 4, wherein the mounting pad has an opening.

6. The conductive film according to claim 1, wherein the inspection pad has a first wire, a second wire, a third wire, a fourth wire, a fifth wire, and a sixth wire as the second thin wire conductor, the first wire intersects the third wire, the second wire, and the fourth wire in that order from one end of the first wire, and the second wire intersects the fifth wire, the first wire, and the sixth wire in that order from one end of the second wire.

7. The conductive film according to claim 1, wherein the first connecting wiring is composed of a plurality of wires.

8. The conductive film according to claim 1, wherein the main wiring and the mounting pad are electrically connected via a second connecting wiring, and the second connecting wiring is composed of a plurality of wires.

9. The conductive film according to claim 1, comprising a sub-wiring formed of a third fine wire conductor provided on the substrate, wherein the sub-wiring is not electrically connected to the main wiring.

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