Wiring circuit board and method for manufacturing the same

Abstract

To improve the overall transparency without impairing the degree of freedom of a wiring pattern of a wired circuit board.SOLUTION: A wired circuit board 100 includes: a transparent substrate 10; a first terminal portion 60 formed on the transparent substrate 10; a second terminal portion 70 formed on the transparent substrate 10; and a wiring layer 50 formed on the transparent substrate 10 so as to connect the first terminal portion 60 and the second terminal portion 70, wherein a slit SL extending continuously from the first terminal portion 60 to the second terminal portion 70 is formed in the wiring layer 50.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wiring circuit board and a method for manufacturing the same.

Background Art

[0002] Conventionally, wiring circuit boards have been used in various electrical or electronic devices. In recent years, it has been considered to dispose a wiring circuit board on a screen or the like of a portable device such as a wearable device. In this case, a wiring circuit board having transparency is used in order to provide good visibility of the screen or the like of the portable device. In a wiring circuit board having transparency, transparency is ensured by using a transparent substrate such as glass. On the other hand, since the wiring on the transparent substrate is formed of metal, it does not have transparency.

[0003] In the wiring board (hereinafter referred to as a wiring circuit board) described in Patent Document 1, a wiring pattern region is formed on a transparent substrate. The wiring pattern region includes a plurality of first-direction wirings having a function as an antenna and a plurality of second-direction wirings. In the wiring pattern region, a plurality of openings are formed by the first-direction wirings and the second-direction wirings being in a lattice shape or a mesh shape.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to visually recognize an object behind through a wiring circuit board having transparency, it is required to make the wiring formed on the wiring circuit board difficult to be visually recognized. According to the wiring circuit board of Patent Document 1 described above, the object behind can be visually recognized through a plurality of rectangular openings.

[0006] However, in the wiring circuit board described in Patent Document 1, the first-direction wiring and the second-direction wiring are arranged in a grid or mesh shape in order to form multiple rectangular openings in the wiring pattern area. Therefore, the degree of freedom of the wiring pattern on the wiring circuit board is limited. There is a need for a transparent wiring circuit board that can realize various functions, not just antennas.

[0007] The objective of the present invention is to provide a wiring circuit board that can improve overall transparency without compromising the freedom of the wiring pattern. [Means for solving the problem]

[0008] (1) A wiring circuit board according to one aspect of the present invention comprises a transparent substrate, a first terminal portion formed on the transparent substrate, a second terminal portion formed on the transparent substrate, and a wiring layer formed on the transparent substrate to connect the first terminal portion and the second terminal portion, wherein a slit extending continuously from the first terminal portion to the second terminal portion is formed in the wiring layer. Linear portions are formed on the transparent substrate, extending from the first terminal portion to the second terminal portion, with the width of the slit being equal from the first terminal portion to the second terminal portion, and the widths of the multiple linear portions being equal. The transparent substrate has first and second main surfaces facing opposite directions, through holes are formed in the transparent substrate so as to penetrate the first main surface and the second main surface, the first terminal portion is formed on the first main surface of the transparent substrate, the second terminal portion is formed on the second main surface of the transparent substrate, the wiring layer is formed on the first and second main surfaces of the transparent substrate so as to connect the first terminal portion and the second terminal portion through the through holes, and the slit constitutes a part of the through holes between the linear portions and is formed to extend continuously from the first terminal portion to the second terminal portion through the through holes. .

[0009] In the wiring circuit board, the first terminal and the second terminal are electrically connected via a wiring layer. A slit is formed in the wiring layer that electrically connects the first and second terminals, extending continuously from the first terminal to the second terminal.

[0010] According to the above configuration, it becomes possible to view objects through areas of the transparent substrate where there are no wiring layers and through slits formed within the wiring layers. In this case, the wiring layers and slits can be formed into any shape. Therefore, it becomes possible to improve the overall transparency of the wiring circuit board without compromising the freedom of the wiring pattern.

[0011] (2) In a wiring circuit board, the maximum width of the wiring layer may be less than or equal to the maximum width of the first terminal portion, and less than or equal to the maximum width of the second terminal portion.

[0012] In this case, the area occupied by the wiring layer, including the slit, does not increase, thus improving the flexibility of the wiring layer layout.

[0013] (3) In a wiring circuit board, the width of the wiring layers may be equal within a predetermined range in the length direction, and the width of the slits may be equal within a predetermined range in the length direction.

[0014] In this case, since the width of the wiring layer and the width of the slit are equal within a predetermined range in the longitudinal direction, the wiring layer and slit can be arranged at a high density on the transparent substrate without reducing the overall transparency of the wiring circuit board. This makes it possible to miniaturize the wiring circuit board while ensuring its transparency.

[0015] (4) In a wiring circuit board, one or more slits are formed in the wiring layer that extend continuously from a first terminal portion to a second terminal portion, and may include a plurality of linear portions that face each other with the slits in between and connect the first terminal portion and the second terminal portion.

[0016] In this case, one or more slits are formed in the wiring layer, thereby dividing the wiring layer into multiple linear sections in the longitudinal direction. This allows for arbitrary design of the transparency of the wiring circuit board and the resistance value of the wiring layer by arbitrarily setting the number of slits, the width of each slit, and the width of the multiple linear sections. This makes it possible to form a wiring layer with a desired resistance value while ensuring the desired transparency.

[0017] (5) In a wiring circuit board, the width of each linear portion may be 2 μm or more and 100 μm or less.

[0018] In this case, by having a width of 2 μm or more for each linear portion, the increase in the resistance value of the wiring layer can be suppressed. Furthermore, by having a width of 100 μm or less for each linear portion, each linear portion can be made less visible. Therefore, the overall transparency of the wiring circuit board can be ensured while suppressing the increase in wiring resistance.

[0019] (6) In the wiring circuit board, the ratio of the width of each linear portion to the maximum width of the first and second terminal portions may be 0.33 or less.

[0020] In this case, each linear portion of the wiring layer can be made less visible compared to the first and second terminal portions. Thereby, it becomes possible to improve the overall visibility of the wiring circuit board.

[0021] (7) In the wiring circuit board, the wiring layer may sequentially include a first sputter film formed of a first metal, a second sputter film formed of a second metal, and a plating layer formed of a third metal from the transparent substrate.

[0022] In this case, by appropriately selecting the first metal, the second metal, and the third metal, it becomes possible to improve the adhesion of the plating layer and to appropriately set the conductivity of the wiring layer. Also, it becomes possible to easily form the wiring layer on the transparent substrate.

[0023] (8) In the wiring circuit board, the wiring layer may be formed in a spiral shape.

[0024] In this case, a wiring layer having slits at a high density can be arranged on the transparent substrate. Thereby, it is possible to miniaturize the wiring circuit board while ensuring the overall transparency of the wiring circuit board. Also, it becomes possible to increase the length of the wiring layer according to the use of the wiring circuit board while suppressing a decrease in the overall transparency of the wiring circuit board.

[0025] (9) In a wiring circuit board, the transparent substrate has first and second main surfaces facing each other, through holes are formed in the transparent substrate so as to penetrate the first main surface and the second main surface, a first terminal portion is formed on the first main surface of the transparent substrate, a second terminal portion is formed on the second main surface of the transparent substrate, the wiring layer is formed on the first main surface and the second main surface of the transparent substrate so as to connect the first terminal portion and the second terminal portion through the through holes, and the slit may be formed so as to continuously extend from the first terminal portion to the second terminal portion through the through hole.

[0026] According to this configuration, on the first main surface and the second main surface, the wiring layer is formed from the first terminal portion on the first main surface through the through hole to the second terminal portion on the second main surface. In this case, it is possible to suppress a decrease in the overall transparency of the wiring circuit board, miniaturize the wiring circuit board, and increase the length of the wiring layer.

[0027] (10) In a wiring circuit board, the wiring layer may include a first wiring portion formed on the first main surface and a second wiring portion formed on the second main surface, the first wiring portion is formed in a spiral shape on the first main surface, and the second wiring portion is formed in a spiral shape on the second main surface.

[0028] In this case, the first wiring portion formed on the first main surface and the second wiring portion formed on the second main surface are formed in a spiral shape. Thereby, a wiring layer having slits at a higher density can be arranged by the transparent substrate. Therefore, it is possible to miniaturize the wiring circuit board while ensuring the overall transparency of the wiring circuit board. Also, it is possible to increase the length of the wiring layer of the wiring circuit board while suppressing a decrease in the overall transparency of the wiring circuit board.

[0029] (11) In a wiring circuit board, the first wiring portion and the second wiring portion may be formed in the same shape so as to overlap each other in a first direction view perpendicular to the first and second main surfaces.

[0030] In this case, the first wiring portion and the second wiring portion are formed to overlap each other when viewed from the first direction, making it difficult to see the wiring layer on the transparent substrate. This allows for an increase in the length of the wiring layer while suppressing a decrease in the overall transparency of the wiring circuit board.

[0031] (12) In a wiring circuit board, the slit includes a first slit portion formed in the first wiring portion and a second slit portion formed in the second wiring portion, and the first slit portion and the second slit portion may be formed in the same shape so that they overlap each other when viewed from a first direction.

[0032] In this case, since the first slit portion and the second slit portion are formed to overlap each other when viewed from the first direction, it becomes possible to make the wiring layer on the transparent substrate less visible. As a result, the length of the wiring layer can be increased while further suppressing the decrease in the overall transparency of the wiring circuit board.

[0033] (13) The coil may be formed by the wiring layer of the wiring circuit board.

[0034] In this case, a transparent coil is realized. Furthermore, by forming slits in the coil, it becomes possible to achieve both low coil resistance and improved transparency of the wiring circuit board.

[0035] (14) The antenna may be formed by a wiring circuit board.

[0036] In this case, a transparent antenna can be realized. Furthermore, it becomes possible to achieve both improved antenna transmission and reception performance and improved transparency of the wiring circuit board.

[0037] (15) A manufacturing method according to another aspect of the present invention includes the steps of preparing a transparent substrate and forming a first terminal portion, a second terminal portion, and a wiring layer connecting the first terminal portion and the second terminal portion on the transparent substrate, wherein the step of forming the wiring layer includes forming a slit in the wiring layer that extends continuously from the first terminal portion to the second terminal portion, forming linear portions that face each other across the slit and extend from the first terminal portion to the second terminal portion, forming the slit and the plurality of linear portions to be equal in width from the first terminal portion to the second terminal portion, and forming the transparent substrate, First main surface and Second main surface The invention includes forming a through hole so as to penetrate the transparent substrate, forming the first terminal portion on the first main surface of the transparent substrate, forming the second terminal portion on the second main surface of the transparent substrate, forming the wiring layer on the first and second main surfaces of the transparent substrate so as to connect the first terminal portion and the second terminal portion through the through hole, and forming the slit so as to constitute a part of the through hole between the linear portions and to extend continuously from the first terminal portion to the second terminal portion through the through hole.

[0038] According to the manufacturing method of the wiring circuit board, a slit is formed in the wiring layer that electrically connects the first terminal portion and the second terminal portion, extending continuously from the first terminal portion to the second terminal portion. This makes it possible to view the object being viewed through the area of ​​the transparent substrate where the wiring layer does not exist and through the slit formed within the wiring layer. In this case, the wiring layer and the slit can be formed in any shape. Therefore, it is possible to improve the overall transparency of the wiring circuit board without compromising the freedom of the wiring pattern. [Effects of the Invention]

[0039] According to the present invention, it is possible to improve overall transparency without compromising the degree of freedom of the wiring pattern. [Brief explanation of the drawing]

[0040] [Figure 1]This is a schematic plan view showing the configuration of a wiring circuit board according to one embodiment. [Figure 2] Figure 1 is a cross-sectional view of the wiring circuit board along line AA. [Figure 3] Figure 1 is a cross-sectional view of the wiring circuit board along line BB. [Figure 4] This is a schematic plan view showing a wiring circuit board for an application example. [Figure 5] This is a schematic bottom view showing a wiring circuit board for an application example. [Figure 6] Figures 4 and 5 are cross-sectional views of the wiring circuit board along the CC line. [Figure 7] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 8] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 9] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 10] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 11] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 12] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 13] This is a schematic cross-sectional view illustrating a method for manufacturing a wiring circuit board. [Figure 14] This figure shows an example of how a wiring circuit board is used. [Figure 15] This figure shows an example of how a wiring circuit board is used. [Figure 16] This is a schematic plan view of a wiring circuit board according to another embodiment. [Figure 17] This is a schematic plan view of a wiring circuit board according to another embodiment. [Figure 18] This is a schematic plan view of a wiring circuit board according to another embodiment. [Figure 19] Figure 18 is a schematic bottom view of the wiring circuit board. [Modes for carrying out the invention]

[0041] Hereinafter, a wiring circuit board according to one embodiment of the present invention and a method for manufacturing the same will be described in detail with reference to the drawings.

[0042] (1) Configuration of a wiring circuit board according to one embodiment Figure 1 is a schematic plan view showing the configuration of a wiring circuit board according to one embodiment. Figure 2 is a cross-sectional view of the wiring circuit board of Figure 1 along line AA. Figure 3 is a cross-sectional view of the wiring circuit board of Figure 1 along line BB. As shown in Figures 1, 2, and 3, the wiring circuit board 100 comprises a transparent substrate 10, a wiring layer 50, a first terminal portion 60, a second terminal portion 70, and a cover insulating layer 80.

[0043] In Figure 1, the transparent substrate 10 has a light transmittance of, for example, 80% or more in the visible light region (e.g., 380 nm to 780 nm) and is electrically insulating. In this embodiment, the transparent substrate 10 is formed of polyimide resin. The transparent substrate 10 may also be formed of an organic insulating material such as polyester resin, acrylic resin, polycarbonate resin, or polyolefin resin. Furthermore, a glass substrate and a transparent ceramic substrate may be used as the transparent substrate 10. The transparent substrate 10 preferably has a thickness of 20 μm to 200 μm. In this embodiment, the transparent substrate 10 has a thickness of, for example, 100 μm.

[0044] A wiring layer 50, a first terminal portion 60, and a second terminal portion 70 are integrally formed on the main surface of the transparent substrate 10. On the transparent substrate 10, the first terminal portion 60 is provided at one end of the wiring layer 50, and the second terminal portion 70 is provided at the other end of the wiring layer 50.

[0045] In this embodiment, the dimension of the wiring layer 50 in the direction extending from the first terminal portion 60 to the second terminal portion 70 is defined as the length, and the dimension in the direction perpendicular to the direction of length is defined as the width. In this embodiment, the wiring layer 50 is formed in a straight line having an equal width from the first terminal portion 60 to the second terminal portion 70. The wiring layer 50 is not limited to a straight line, but may be formed in a curved shape, a bent shape, or any other arbitrary shape.

[0046] In this embodiment, the width of the wiring layer 50 is less than or equal to the maximum width of the first terminal portion 60 and the maximum width of the second terminal portion 70. Preferably, the wiring layer 50 has a width of 6 μm or more and 500 μm or less. In this embodiment, the wiring layer 50 has a width of 300 μm.

[0047] In this embodiment, a single slit SL is formed in the wiring layer 50, extending continuously from the first terminal portion 60 to the second terminal portion 70. In this embodiment, the slit SL is formed linearly so as to have the same width from the first terminal portion 60 to the second terminal portion 70. However, a part of the slit SL may have a different width than other parts. It is preferable that the slit SL has a width of 2 μm to 300 μm. In this embodiment, the slit SL has a width of 100 μm. As a result, the wiring layer 50 is composed of linear portions 51 and 52 extending from the first terminal portion 60 to the second terminal portion 70, facing each other with the slit SL in between. In this embodiment, the slit SL is formed in the wiring layer 50 so as to have the same width as the linear portions 51 and 52. It is preferable that the linear portions 51 and 52 have a width of 2 μm to 100 μm. In this case, by having a width of 2 μm or more for the linear portions 51 and 52, the increase in the resistance value of the wiring layer 50 can be suppressed. Also, by having a width of 100 μm or less for the linear portions 51 and 52, the linear portions 51 and 52 can be made less visible. Therefore, the overall transparency of the wiring circuit board 100 can be ensured while suppressing the increase in wiring resistance.

[0048] In this embodiment, the linear portions 51 and 52 each have a width of 100 μm. The ratio of the width of each linear portion 51 and 52 to the width of the wiring layer 50 may be 0.33 or less. Alternatively, the ratio of the width of each linear portion 51 and 52 to the maximum width of the first terminal portion 60 and the second terminal portion 70 may be set to 0.33 or less. In this case, the linear portions 51 and 52 of the wiring layer 50 can be made less visible compared to the first terminal portion 60 and the second terminal portion 70.

[0049] As shown in Figures 2 and 3, the wiring layer 50, the first terminal portion 60, and the second terminal portion 70 include the first sputtered film 20, the second sputtered film 30, and the plating layer 40. The first sputtered film 20 and the second sputtered film 30 are laminated in this order on the upper surface of the transparent substrate 10 by sputtering.

[0050] In this embodiment, the first sputtered film 20 is formed of chromium. The first sputtered film 20 may be formed of a metal or alloy containing one or more elements from among titanium (Ti), molybdenum (Mo), tungsten (W), nickel (Ni), aluminum (Al), and chromium (Cr). In this embodiment, the second sputtered film 30 is formed of copper. The second sputtered film 30 may be formed of a metal or alloy containing one or more elements from among gold, silver, platinum, lead, tin, nickel, cobalt, indium, rhodium, chromium, tungsten, and ruthenium. In this embodiment, the plating layer 40 is formed by electrolytic copper plating. The plating layer 40 may be formed of a metal or alloy containing one or more elements from among gold, silver, platinum, lead, tin, nickel, cobalt, indium, rhodium, chromium, tungsten, and ruthenium.

[0051] The first sputtered film 20 preferably has a thickness of 0.001 μm or more and 0.005 μm or less. In this embodiment, the first sputtered film 20 is 0.005 μm thick. The second sputtered film 30 preferably has a thickness of 0.001 μm or more and 0.015 μm or less. In this embodiment, the second sputtered film 30 is 0.015 μm thick. The plating layer 40 preferably has a thickness of 5 μm or more and 1000 μm or less. In this embodiment, the plating layer 40 is 100 μm thick.

[0052] As shown in Figure 3, the first terminal portion 60 and the second terminal portion 70 have a plating film 41 on the plating layer 40. For example, gold or nickel can be used for the plating film 41. Preferably, the plating film 41 has a thickness of 0.01 μm or more and 10 μm or less. In this embodiment, the plating film 41 is 3 μm thick. A base insulating layer made of polyimide resin or the like may be provided between the transparent substrate 10 and the first sputtered film 20.

[0053] A cover insulating layer 80 is formed on the transparent substrate 10 so as to cover the wiring layer 50. As shown in Figure 3, the plating films 41 of the first terminal portion 60 and the second terminal portion 70 are exposed from the upper surface of the cover insulating layer 80.

[0054] The cover insulating layer 80 may be formed from other transparent synthetic resins such as epoxy resin, cycloolefin polymer resin, polycarbonate resin, polyethylene terephthalate resin, polystyrene resin, or polyethylene naphthalate resin. In this embodiment, the cover insulating layer 80 is formed from a transparent photosensitive polyimide resin.

[0055] (2) Examples of applications of the wiring circuit board 100 Next, an example of the application of the wiring circuit board 100 shown in Figure 1 will be described. The wiring circuit board 100 in the example will be called the wiring circuit board 100a. Figure 4 is a schematic plan view showing the wiring circuit board 100a in the example. Figure 5 is a schematic bottom view showing the wiring circuit board 100a in the example. Figure 6 is a cross-sectional view of the wiring circuit board 100a in Figures 4 and 5 along the CC line. In Figure 4, the upper surface of the transparent substrate 10 is called the first main surface 11A. In Figure 5, the lower surface of the transparent substrate 10 is called the second main surface 11B. In this example, the transparent substrate 10 has through holes AP that penetrate the first main surface 11A and the second main surface 11B. Also in this example, the wiring layer 50 includes a first wiring portion 50A and a second wiring portion 50B.

[0056] As shown in Figure 4, a first wiring portion 50A and a first terminal portion 60 are formed on the first main surface 11A of the transparent substrate 10. Specifically, the first wiring portion 50A is formed in a spiral shape extending inward from the first terminal portion 60. The starting end of the first wiring portion 50A is integrally formed with the first terminal portion 60. In this embodiment, the first wiring portion 50A has a spiral shape with 2 turns. However, the first wiring portion 50A may be formed with any number of turns. The end of the first wiring portion 50A is located on the through hole AP.

[0057] As shown in Figure 5, a second wiring portion 50B and a second terminal portion 70 are formed on the second main surface 11B of the transparent substrate 10. Specifically, the second wiring portion 50B is formed in a spiral shape extending outward from the through hole AP. The starting end of the second wiring portion 50B is located on the through hole AP. In this embodiment, the second wiring portion 50B has a spiral shape with 2 turns. However, the second wiring portion 50B may be formed with any number of turns. The end of the second wiring portion 50B is integrally formed with the second terminal portion 70.

[0058] In the wiring circuit board 100a of this example, similar to the wiring circuit board 100 in Figure 1, a slit SL is formed at the center of the wiring layer 50 in the width direction, extending continuously from the first terminal portion 60 to the second terminal portion 70. The slit SL is formed continuously from the first wiring portion 50A through a through hole AP to the second wiring portion 50B. In this case, the through hole AP is part of the slit SL.

[0059] As shown in Figure 6, in this example, the first sputtered film 20, the second sputtered film 30, and the plating layer 40 are laminated in this order on the first main surface 11A and the second main surface 11B of the transparent substrate 10 of the wiring circuit board 100a. Similarly, the first sputtered film 20, the second sputtered film 30, and the plating layer 40 are laminated in this order on the inner circumferential surface of the through hole AP of the transparent substrate 10. In this example, the wiring layers 50 formed on the first main surface 11A and the second main surface 11B of the transparent substrate 10 are arranged to overlap each other in a plan view. Similarly, the slits SL formed on the first main surface 11A and the second main surface 11B of the transparent substrate 10 are arranged to overlap each other in a plan view.

[0060] A cover insulating layer 80a is formed on the first main surface 11A of the transparent substrate 10 so as to cover the wiring layer 50. The upper surface of the first terminal portion 60 is exposed on the upper surface of the cover insulating layer 80a (not shown). A cover insulating layer 80b is formed on the second main surface 11B of the transparent substrate 10 so as to cover the wiring layer 50. The lower surface of the second terminal portion 70 is exposed on the lower surface of the cover insulating layer 80b (not shown). With these configurations, the first terminal portion 60 formed on the first main surface 11A of the transparent substrate 10 and the second terminal portion 70 formed on the second main surface 11B of the transparent substrate 10 are electrically connected by the wiring layer 50.

[0061] As shown in Figure 4, a conductive wire C1 is connected to the first terminal 60. The wire C1 is also connected to the external terminal IT of the wiring circuit board 100a. As shown in Figure 5, a conductive wire C2 is connected to the second terminal 70. The wire C2 is also connected to the external terminal OT of the wiring circuit board 100a.

[0062] In this example, when using the wiring circuit board 100a, another insulating film may be formed on the upper surface of the cover insulating layer 80a, and another insulating film may be formed on the lower surface of the cover insulating layer 80b. As a result, the conductor C1 is covered with an insulating film, and the conductor C2 is covered with an insulating film.

[0063] (3) Method for manufacturing the wiring circuit board 100a Figures 7 to 13 are schematic cross-sectional views illustrating the manufacturing method of the wiring circuit board 100a. In this embodiment, the wiring circuit board 100a is manufactured using a roll-to-roll method.

[0064] First, a roll (hereinafter referred to as the "feed-out roll") on which a long transparent substrate 10 is wound is prepared, and the transparent substrate 10 is fed out from the feed-out roll. The transparent substrate 10 fed out from the feed-out roll is then wound onto another roll (hereinafter referred to as the "wind-up roll"). Figure 7 shows a cross-section of a portion of the transparent substrate 10 fed out from the feed-out roll. According to the roll-to-roll method, the long transparent substrate 10 moves in the longitudinal direction, and the following processes are sequentially performed on each region of the transparent substrate 10.

[0065] As shown in Figure 7, through-holes AP are formed in a predetermined area of ​​the transparent substrate 10 so as to penetrate the first main surface 11A and the second main surface 11B. Next, as shown in Figure 8, a first sputtered film 20 is formed on the first main surface 11A, the second main surface 11B, and the inner circumferential surface of the through-holes AP of the transparent substrate 10 by sputtering. In this example, chromium is used as the material for the first sputtered film 20.

[0066] Next, as shown in Figure 9, a second sputtered film 30 is further laminated on the first sputtered film 20 formed on the surface of the transparent substrate 10 by sputtering. In this example, copper is used as the material for the second sputtered film 30.

[0067] In this state, after photoresist is applied to the surface of the second sputtered film 30, exposure and development processes are performed to form a resist film RF having a predetermined pattern on the second sputtered film 30, as shown in Figure 10. In this state, a plating layer 40 is formed by electrolytic copper plating in the areas on the second sputtered film 30 where the resist film RF is not formed. In this example, the plating layer 40 on the first main surface 11A and the plating layer 40 on the second main surface 11B of the transparent substrate 10 are formed so as to overlap each other in a plan view.

[0068] Subsequently, the resist film RF is removed. As a result, a plating layer 40 with slits SL is formed on the first main surface 11A and the second main surface 11B of the transparent substrate 10, as shown in Figure 11. After that, an etching resist (not shown) is applied to the plating layer 40, and then etching is performed on the areas of the first sputtered film 20 and the second sputtered film 30 where the plating layer 40 is not formed. For etching, wet etching or dry etching is used.

[0069] As a result, as shown in Figure 12, a wiring layer 50 having slits SL is formed on the first main surface 11A and the second main surface 11B of the transparent substrate 10. Note that the slits SL on the first main surface 11A and the slits SL on the second main surface 11B of the transparent substrate 10 are formed to overlap each other in a plan view.

[0070] Next, as shown in Figure 13, a cover insulating layer 80a made of transparent photosensitive polyimide is formed on the first main surface 11A of the transparent substrate 10 so as to cover the wiring layer 50. Similarly, a cover insulating layer 80b made of transparent photosensitive polyimide is formed on the second main surface 11B of the transparent substrate 10 so as to cover the wiring layer 50.

[0071] (4) Example of use of wiring circuit board 100a Figures 14 and 15 illustrate examples of the use of the wiring circuit board 100a. In Figures 14 and 15, the configuration of the wiring circuit board 100a is omitted. As shown in Figure 14, the wiring circuit board 100a is provided, for example, on the lens L of smart glasses SG. In this case, the wiring circuit board 100a may be provided so as to be attached to the lens L of the smart glasses SG. Alternatively, the wiring circuit board 100a may be formed to be integral with the lens L of the smart glasses SG. In this case, the transparent substrate 10 may constitute the lens L.

[0072] As shown in Figure 15, the wiring circuit board 100a may be provided on, for example, the screen SC of a smartwatch SW. Alternatively, the wiring circuit board 100a may be provided on the liquid crystal screen of a smartphone or tablet device. In this case, the first terminal portion 60 and the second terminal portion 70 can be provided at the edge of the field of view or outside the field of view.

[0073] The smart glasses SG in Figure 14 are equipped with an image display device DP. Similarly, the smartwatch SW in Figure 15 is equipped with an image display device DP. The first terminal portion 60 and the second terminal portion 70 of the wiring circuit board 100a in Figures 14 and 15 are connected to the image display device DP through conductors C1, C2 and external terminals IT, OT (see Figures 4 and 5). For example, the wiring layer 50 of the wiring circuit board 100a is used as a power supply coil that receives power from a power supply device. In this case, the battery of the image display device DP can be charged by setting the wiring circuit board 100a of the smart glasses SG or smartwatch SW in the power supply device.

[0074] Furthermore, the wiring layer 50 of the wiring circuit board 100a may be used as an antenna. In this case, the image display device DP of the smart glasses SG or smartwatch SW can receive image data via communication.

[0075] (5) Effects of the embodiment In the wiring circuit board 100 of this embodiment, the first terminal portion 60 and the second terminal portion 70 are electrically connected via the wiring layer 50. A slit SL is formed in the wiring layer 50 that electrically connects the first terminal portion 60 and the second terminal portion 70, extending continuously from the first terminal portion 60 to the second terminal portion 70. With this configuration, it becomes possible to view objects through the areas of the transparent substrate 10 where the wiring layer 50 is not present and through the slit SL formed within the wiring layer 50. In this case, the wiring layer 50 and the slit SL can be formed into any shape. Therefore, it becomes possible to improve the overall transparency of the wiring circuit board 100 without impairing the freedom of the wiring pattern.

[0076] Furthermore, in the wiring circuit board 100 of this embodiment, the maximum width of the wiring layer 50 is less than or equal to the maximum width of the first terminal portion 60 and the second terminal portion 70. In this case, the area occupied by the wiring layer 50 including the slit SL does not increase, thus improving the degree of freedom in the layout of the wiring layer 50.

[0077] Furthermore, in the wiring circuit board 100 of this embodiment, the width of the wiring layer 50 is equal in the range from the first terminal portion 60 to the second terminal portion 70, and the width of the slit SL is equal in the range from the first terminal portion 60 to the second terminal portion 70. As a result, the wiring layer 50 and the slit SL can be arranged at a high density on the transparent substrate 10 without reducing the overall transparency of the wiring circuit board 100. Consequently, it becomes possible to miniaturize the wiring circuit board 100 while ensuring its transparency.

[0078] In the wiring circuit board 100a of this embodiment, a wiring layer 50 is formed on the first main surface 11A and the second main surface 11B, extending from the first terminal portion 60 on the first main surface 11A through the through hole AP to the second terminal portion 70 on the second main surface 11B. In this case, it is possible to suppress a decrease in the overall transparency of the wiring circuit board 100a and to increase the length of the wiring layer 50 while miniaturizing the wiring circuit board 100a.

[0079] Furthermore, in the wiring circuit board 100a of this embodiment, the first wiring portion 50A formed on the first main surface 11A and the second wiring portion 50B formed on the second main surface 11B are formed in a spiral shape. This allows the wiring layer 50 having slits to be arranged on the transparent substrate 10 at a high density. Therefore, the wiring circuit board 100a can be miniaturized while ensuring the overall transparency of the wiring circuit board 100a. In addition, the length of the wiring layer 50 of the wiring circuit board 100a can be increased while suppressing a decrease in the overall transparency of the wiring circuit board 100a.

[0080] Furthermore, in the wiring circuit board 100a of this embodiment, the first wiring portion 50A and slit SL formed on the first main surface 11A and the second wiring portion 50B and slit SL formed on the second main surface 11B are formed to overlap each other, making it possible to make the wiring layer 50 on the transparent substrate 10 difficult to see. As a result, the length of the wiring layer 50 can be increased while suppressing a decrease in the overall transparency of the wiring circuit board 100.

[0081] (6) Other embodiments (6-1) In the wiring circuit board 100 of the above embodiment, the wiring layer 50 is formed to have an equal width from the first terminal portion 60 to the second terminal portion 70, but the present invention is not limited thereto. The wiring layer 50 may be formed to have an equal width within a predetermined range. Also, the slit SL is formed to have an equal width from the first terminal portion 60 to the second terminal portion 70, but it may be formed to have an equal width within a predetermined range.

[0082] (6-2) In the above embodiment, the first terminal portion 60 and the second terminal portion 70 of the wiring circuit board 100 are formed in a circular shape, but the present invention is not limited thereto. Also, in the above embodiment, the width of the wiring layer 50 is formed to be smaller than the maximum width of the first terminal portion 60 and the second terminal portion 70, but the present invention is not limited thereto. Figure 16 is a schematic plan view of the wiring circuit board 100 according to another embodiment. As shown in Figure 16, the first terminal portion 60 and the second terminal portion 70 may be formed to have a rectangular shape. Also, the first terminal portion 60 and the second terminal portion 70 may have other shapes such as an ellipse or a polygon. The width of the wiring layer 50 may be formed to be equal to the maximum width of the first terminal portion 60 and the second terminal portion 70.

[0083] (6-3) In the wiring circuit board 100 of the above embodiment, two linear portions 51 and 52 are formed by forming a single slit SL in the wiring layer 50, but the present invention is not limited thereto. Figure 17 is a schematic plan view of a wiring circuit board 100 according to yet another embodiment. As shown in Figure 17, a plurality of slits SL (three in the example of Figure 17) may be formed in the wiring layer 50, thereby forming three or more linear portions (four in the example of Figure 17). With this configuration, the transparency of the wiring circuit board 100 and the resistance value of the wiring layer 50 can be arbitrarily designed by arbitrarily setting the number of slits SL, the width of each slit SL, and the width of the plurality of linear portions. As a result, a wiring layer 50 having a desired resistance value can be formed in the wiring circuit board 100 while ensuring the desired transparency.

[0084] (6-4) In the wiring circuit board 100a of the above embodiment, the first and second wiring portions 50A and 50B formed on the first main surface 11A and the second main surface 11B of the transparent substrate 10 are formed in a spiral shape so as to overlap each other in a plan view, but the present invention is not limited thereto. Figure 18 is a schematic plan view of a wiring circuit board 100 according to yet another embodiment. Figure 19 is a schematic bottom view of the wiring circuit board 100 of Figure 18. As shown in Figure 18, the first wiring portion 50A may be formed linearly on the first main surface 11A. Also, as shown in Figure 19, the second wiring portion 50B may be formed linearly on the second main surface 11B. Furthermore, as shown in Figures 18 and 19, the first wiring portion 50A and the second wiring portion 50B may be formed so as not to overlap each other in a plan view.

[0085] (6-5) In the wiring circuit board 100 of the above embodiment, the width of the wiring layer 50 is less than or equal to the maximum width of the first terminal portion 60 and the maximum width of the second terminal portion 70, but the present invention is not limited thereto. The width of the wiring layer 50 may be greater than the maximum width of the first terminal portion 60 and the maximum width of the second terminal portion 70. [Explanation of Symbols]

[0086] 10…Transparent substrate, 11A…First main surface, 11B…Second main surface, 20…First sputtered film, 30…Second sputtered film, 40…Plating layer, 41…Plating film, 50…Wiring layer, 50A…First wiring portion, 50B…Second wiring portion, 51, 52…Linear portion, 60…First terminal portion, 70…Second terminal portion, 80, 80a, 80b…Insulating layer, 100, 100a…Wiring circuit board, AP…Through hole, C1, C2…Conducting wire, IT…External terminal, L…Lens, OT…External terminal, RF…Resist film, SC…Screen, SG…Smart glasses, SL…Slit, SW…Smartwatch

Claims

1. Transparent substrate and A first terminal portion formed on the transparent substrate, A second terminal portion formed on the transparent substrate, The device comprises a wiring layer formed on the transparent substrate so as to connect the first terminal portion and the second terminal portion, A slit is formed in the wiring layer, extending continuously from the first terminal portion to the second terminal portion. A linear portion is formed extending from the first terminal portion to the second terminal portion, which are opposite each other across the slit. The width of the slit is equal from the first terminal portion to the second terminal portion, and the widths of the plurality of linear portions are formed to be equal. The transparent substrate has first and second main surfaces facing opposite directions. The transparent substrate has through holes formed so as to penetrate the first main surface and the second main surface. The first terminal portion is formed on the first main surface of the transparent substrate. The second terminal portion is formed on the second main surface of the transparent substrate. The wiring layer is formed on the first and second main surfaces of the transparent substrate so as to connect the first terminal portion and the second terminal portion through the through-hole, The slit is formed to constitute a part of the through hole between the linear portions and to extend continuously from the first terminal portion to the second terminal portion through the through hole. Wiring circuit board.

2. The wiring circuit board according to claim 1, wherein the maximum width of the wiring layer is less than or equal to the maximum width of the first terminal portion and less than or equal to the maximum width of the second terminal portion.

3. One or more slits are formed in the wiring layer, extending continuously from the first terminal portion to the second terminal portion. A wiring circuit board according to claim 1 or 2, comprising a plurality of linear portions that face each other with a slit in between and connect the first terminal portion and the second terminal portion.

4. The wiring circuit board according to claim 3, wherein the width of each linear portion is 2 μm or more and 100 μm or less.

5. The wiring circuit board according to claim 3 or 4, wherein the ratio of the width of each linear portion to the maximum width of the first and second terminal portions is 0.33 or less.

6. The wiring circuit board according to any one of claims 1 to 3, wherein the wiring layer includes, in order from the transparent substrate, a first sputtered film formed of a first metal, a second sputtered film formed of a second metal, and a plating layer formed of a third metal.

7. The wiring circuit board according to any one of claims 1 to 6, wherein the wiring layer is formed in a spiral shape.

8. The wiring layer includes a first wiring portion formed on the first main surface and a second wiring portion formed on the second main surface. The first wiring portion is formed in a spiral shape on the first main surface, The wiring circuit board according to claim 1, wherein the second wiring portion is formed in a spiral shape on the second main surface.

9. The wiring circuit board according to claim 8, wherein the first wiring portion and the second wiring portion are formed to be the same shape so as to overlap each other when viewed in a first direction perpendicular to the first and second main surfaces.

10. The slit includes a first slit portion formed in the first wiring portion and a second slit portion formed in the second wiring portion. The wiring circuit board according to claim 9, wherein the first slit portion and the second slit portion are formed to be the same shape so as to overlap each other when viewed from the first direction.

11. A coil formed by the wiring layer of a wiring circuit board according to any one of claims 1 to 10.

12. An antenna formed by a wiring circuit board as described in any one of claims 1 to 10.

13. The process of preparing the transparent substrate, The process includes the step of forming a first terminal portion, a second terminal portion, and a wiring layer connecting the first terminal portion and the second terminal portion on the transparent substrate, The step of forming the wiring layer is, A slit is formed in the wiring layer, extending continuously from the first terminal portion to the second terminal portion. A linear portion is formed extending from the first terminal portion to the second terminal portion, which are opposite each other across the slit. The width of the slit is equal from the first terminal portion to the second terminal portion, and the widths of the plurality of linear portions are formed to be equal. Through holes are formed in the transparent substrate so as to penetrate the first main surface and the second main surface. The first terminal portion is formed on the first main surface of the transparent substrate. The second terminal portion is formed on the second main surface of the transparent substrate. The wiring layer is formed on the first main surface and the second main surface of the transparent substrate so as to connect the first terminal portion and the second terminal portion through the through hole. The slit is formed to constitute a part of the through hole between the linear portions and to extend continuously from the first terminal portion to the second terminal portion through the through hole. A method for manufacturing a wiring circuit board.

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