JP2022163867A - Wiring board, module, wiring board manufacturing method, and module manufacturing method - Google Patents

Abstract

A wiring board, a module, a wiring board manufacturing method, and a module manufacturing method capable of improving electrical connectivity between a power supply line and a power supply part are provided. A wiring board (10) includes a substrate (11), a mesh wiring layer (20) disposed on the substrate (11) and including a plurality of wirings (21), a power supply section (40) electrically connected to the mesh wiring layer (20), and the substrate (10). and a protective layer 17 arranged thereon to cover the mesh wiring layer 20 and the power supply portion 40 . The substrate 11 has a transmittance of 85% or more for light having a wavelength of 400 nm or more and 700 nm or less. The thickness T2 of the protective layer 17 is 0.05 μm or more and 1.8 μm or less. The pencil hardness of the surface of the protective layer 17 is B or more and 2H or less. [Selection drawing] Fig. 4

Description

The embodiments of the present disclosure relate to a wiring board, a module, a wiring board manufacturing method, and a module manufacturing method.

Currently, mobile terminal devices such as smartphones and tablets are becoming more sophisticated, smaller, thinner and lighter. Since these mobile terminal devices use a plurality of communication bands, they require a plurality of antennas corresponding to the communication bands. For example, mobile terminal devices include telephone antennas, WiFi (Wireless Fidelity) antennas, 3G (Generation) antennas, 4G (Generation) antennas, LTE (Long Term Evolution) antennas, and Bluetooth (registered trademark) antennas. , an NFC (Near Field Communication) antenna, and the like. However, with the miniaturization of mobile terminal devices, the mounting space for antennas is limited, and the degree of freedom in antenna design is narrowing. Also, since the antenna is built in a limited space, the radio sensitivity is not always satisfactory.

For this reason, film antennas have been developed that can be mounted in the display areas of portable terminal devices. This film antenna is a transparent antenna in which an antenna pattern is formed on a transparent base material, and the antenna pattern is formed in a mesh shape with a conductor portion as a formation portion of an opaque conductor layer and a large number of openings as non-formation portions. of conductive mesh layers.

JP 2011-66610 A Patent No. 5636735 Patent No. 5695947

By the way, in the film antenna, in order to protect the conductive mesh layer and the feeding section for electrically connecting the conductive mesh layer to an external device, the conductive mesh layer and the feeding section are covered with a protective layer. is preferred. However, when the power supply portion is covered with a protective layer, there is a possibility that the electrical connection between the power supply portion and the power supply line for connecting the film antenna to an external device may become unstable.

An object of the present embodiment is to provide a wiring board, a module, a method for manufacturing the wiring board, and a method for manufacturing the module, which can improve electrical connectivity between the power supply line and the power supply part. be one.

A wiring board according to an embodiment of the present disclosure includes a board, a mesh wiring layer disposed on the board and including a plurality of wirings, a power supply section electrically connected to the mesh wiring layer, and and a protective layer that covers the mesh wiring layer and the power feeding portion, the substrate has a transmittance of 85% or more for light with a wavelength of 400 nm or more and 700 nm or less, and the protective layer has a thickness of 0 05 μm or more and 1.8 μm or less, and the surface of the protective layer has a pencil hardness of B or more and 2H or less.

In the wiring board according to one embodiment of the present disclosure, the protective layer may have a dielectric loss tangent of 0.005 or less.

In the wiring board according to one embodiment of the present disclosure, the protective layer may contain an acrylic resin or a polyester resin.

In the wiring board according to one embodiment of the present disclosure, the protective layer may contain silicon dioxide.

In the wiring board according to one embodiment of the present disclosure, the wiring board may have a radio wave transmission/reception function.

A module according to an embodiment of the present disclosure includes a wiring board according to the present disclosure, and a power supply line crimped to the wiring board via an anisotropic conductive film containing conductive particles, wherein the anisotropic conductive The film is arranged so as to face the power supply section, and the power supply line is electrically connected to the power supply section by the conductive particles entering the protective layer.

A method of manufacturing a wiring board according to an embodiment of the present disclosure includes a step of preparing a board, a mesh wiring layer including a plurality of wirings on the board, and a power supply section electrically connected to the mesh wiring layer. and forming a protective layer on the substrate so as to cover the mesh wiring layer and the power feeding portion, wherein the substrate has a transmittance of light with a wavelength of 400 nm or more and 700 nm or less. is 85% or more, the thickness of the protective layer is 0.05 μm or more and 1.8 μm or less, and the pencil hardness of the surface of the protective layer is B or more and 2H or less.

A method for manufacturing a module according to an embodiment of the present disclosure includes steps of preparing a wiring board according to the present disclosure, crimping a feed line to the wiring board via an anisotropic conductive film containing conductive particles, wherein the anisotropic conductive film is arranged to face the power supply section, and the power supply line is electrically connected to the power supply section by the conductive particles entering the protective layer. It is a method of manufacturing a module.

According to the embodiments of the present disclosure, it is possible to improve the electrical connectivity between the feeder and the feeder.

FIG. 1 is a plan view showing a wiring board according to one embodiment. FIG. 2 is an enlarged plan view (enlarged view of part II in FIG. 1) showing the wiring board according to the embodiment. FIG. 3 is a cross-sectional view (cross-sectional view along line III-III in FIG. 2) showing the wiring board according to one embodiment. FIG. 4 is a cross-sectional view (cross-sectional view taken along line IV-IV in FIG. 2) showing the wiring board according to one embodiment. FIG. 5 is a plan view showing an image display device according to one embodiment. FIG. 6 is a cross-sectional view (cross-sectional view along the line VI-VI in FIG. 5) showing the image display device according to one embodiment. 7A to 7F are cross-sectional views showing a method of manufacturing a wiring board according to one embodiment. 8(a)-(c) are cross-sectional views showing a module manufacturing method according to one embodiment. FIG. 9 is an enlarged plan view showing a modification of the wiring board according to one embodiment.

First, an embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 to 8 are diagrams showing this embodiment.

Each figure shown below is shown typically. Therefore, the size and shape of each part are appropriately exaggerated for easy understanding. In addition, it is possible to modify and implement as appropriate without departing from the technical idea. In addition, in each figure shown below, the same code|symbol is attached|subjected to the same part and detailed description may be partially abbreviate|omitted. In addition, numerical values such as dimensions and material names of each member described in this specification are examples as an embodiment, and are not limited to these, and can be appropriately selected and used. In this specification, terms specifying shapes and geometrical conditions, such as parallel, orthogonal, and perpendicular terms, not only have strict meanings but also include substantially the same states.

In this embodiment, the "X direction" is a direction parallel to one side of the substrate. "Y direction" is a direction perpendicular to the X direction and parallel to the other sides of the substrate. The “Z direction” is a direction perpendicular to both the X direction and the Y direction and parallel to the thickness direction of the wiring board. Moreover, the “surface” refers to a surface on the positive side in the Z direction. "Back surface" refers to the surface on the negative side in the Z direction. In the present embodiment, the case where the mesh wiring layer 20 has a radio wave transmission/reception function (function as an antenna) will be described as an example. functions).

[Configuration of Wiring Board]
The configuration of the wiring board according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 to 4 are diagrams showing a wiring board according to this embodiment.

As shown in FIG. 1, the wiring board 10 according to the present embodiment is arranged, for example, on a display of an image display device. Such a wiring board 10 includes a substrate 11 having transparency, a mesh wiring layer 20 arranged on the substrate 11, a power supply portion 40 electrically connected to the mesh wiring layer 20, and a wiring board 11 arranged on the substrate 11. and a protective layer 17 that covers the mesh wiring layer 20 and the power supply section 40 .

Among them, the substrate 11 has a substantially rectangular shape in plan view, with its longitudinal direction parallel to the Y direction and its short direction parallel to the X direction. The substrate 11 is transparent, has a substantially flat plate shape, and has a substantially uniform thickness as a whole. _The length L1 of the substrate 11 in the longitudinal direction (Y direction) can be selected, for example, in the range of 2 mm or more and 300 mm or less, preferably in the range of 100 mm or more and 200 mm or less. The length L2 of the substrate 11 in the lateral direction (X direction) can be selected, for example, in the range of ₂ mm or more and 300 mm or less, preferably in the range of 50 mm or more and 100 mm or less. The substrate 11 may have rounded corners.

The dielectric constant of the substrate 11 is not particularly limited, but may be 2.0 or more and 10.0 or less. The dielectric constant of the substrate 11 can be measured according to IEC62562. Specifically, first, a test piece is prepared by cutting out a portion of the substrate 11 where the mesh wiring layer 20 is not arranged. Alternatively, a portion of the substrate 11 where the mesh wiring layer 20 is arranged may be cut out, and the mesh wiring layer 20 may be removed by etching or the like. The dimensions of the test piece are 10 mm or more and 20 mm or less in width and 50 mm or more and 100 mm or less in length. Next, the dielectric constant is measured according to IEC 62562. The dielectric constant of substrate 11 can also be measured according to ASTM D150.

The material of the substrate 11 may be any material that has transparency in the visible light region and electrical insulation. Although the material of the substrate 11 is polyethylene terephthalate in this embodiment, the material is not limited to this. Examples of materials for the substrate 11 include polyester resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, polycarbonate resins, polyimide resins, polyolefin resins such as cycloolefin polymers, and triacetyl cellulose. It is preferable to use an organic insulating material such as a cellulose resin material. Alternatively, as the material of the substrate 11, an organic insulating material such as cycloolefin polymer (for example, ZF-16 manufactured by Nippon Zeon Co., Ltd.) or polynorbornene polymer (manufactured by Sumitomo Bakelite Co., Ltd.) may be used. Also, as the material of the substrate 11, glass, ceramics, or the like can be appropriately selected depending on the application. Although the substrate 11 is illustrated as being composed of a single layer, it is not limited to this, and may have a structure in which a plurality of base materials or layers are laminated. Further, the substrate 11 may be film-like or plate-like. Therefore, the thickness of the substrate ₁₁ is not particularly limited and can be appropriately selected according to the application. can be in the range of

Also, the dielectric loss tangent of the substrate 11 may be 0.002 or less, preferably 0.001 or less. Although there is no particular lower limit for the dielectric loss tangent of the substrate 11, it may be greater than zero. When the dielectric loss tangent of the substrate 11 is within the above range, especially when the electromagnetic waves (for example, millimeter waves) transmitted and received by the mesh wiring layer 20 are of high frequency, the gain (sensitivity) loss associated with the transmission and reception of the electromagnetic waves can be reduced. can. Note that the lower limit of the dielectric loss tangent of the substrate 11 is not particularly limited. The dielectric constant of the substrate 11 is not particularly limited, but may be 2.0 or more and 10.0 or less.

The dielectric loss tangent of the substrate 11 can be measured according to IEC62562. Specifically, first, a test piece is prepared by cutting out a portion of the substrate 11 where the mesh wiring layer 20 is not formed. Alternatively, the substrate 11 on which the mesh wiring layer 20 is formed may be cut out and the mesh wiring layer 20 may be removed by etching or the like. The dimensions of the test piece are 10 mm to 20 mm in width and 50 mm to 100 mm in length. Next, the dielectric loss tangent is measured according to IEC 62562. The dielectric constant and dielectric loss tangent of the substrate 11 can also be measured according to ASTM D150.

Further, the substrate 11 may have a transmittance of 85% or more, preferably 90% or more, for visible light (light having a wavelength of 400 nm or more and 700 nm or less). There is no particular upper limit for the visible light transmittance of the substrate 11, but it may be, for example, 100% or less. By setting the visible light transmittance of the substrate 11 within the above range, the transparency of the wiring substrate 10 can be enhanced, and the display 91 (described later) of the image display device 90 can be easily viewed. Note that visible light refers to light having a wavelength of 400 nm to 700 nm. Further, when the visible light transmittance is 85% or more, the absorbance of the substrate 11 is measured using a known spectrophotometer (for example, spectrometer V-670 manufactured by JASCO Corporation). In this case, it means that the transmittance is 85% or more in the entire wavelength range from 400 nm to 700 nm.

In FIG. 1, a plurality (three) of mesh wiring layers 20 are present on a substrate 11 and correspond to different frequency bands. That is, the plurality of mesh wiring layers 20 have different lengths (lengths in the Y direction) La, and each have _a length corresponding to a specific frequency band. The length La of the mesh _wiring layer 20 is longer as the corresponding frequency band is lower. When the wiring board 10 is arranged on, for example, a display 91 (see FIG. 5 described later) of an image display device 90, each mesh wiring layer 20 can be used as an antenna for a telephone or for WiFi when the wiring board 10 has a radio wave transmitting/receiving function. Antenna, antenna for 3G, antenna for 4G, antenna for 5G, antenna for LTE, antenna for Bluetooth (registered trademark), antenna for NFC, or the like may be supported. Alternatively, if the wiring board 10 does not have a radio wave transmitting/receiving function, each mesh wiring layer 20 has functions such as hovering (a function that allows the user to operate without directly touching the display), fingerprint authentication, heater, and noise reduction. (Shield) and other functions may be achieved. Moreover, the mesh wiring layer 20 may be present only in a partial area of the substrate 11 instead of being present all over the substrate 11 .

Each mesh wiring layer 20 has a substantially rectangular shape in plan view. Each mesh wiring layer 20 has its longitudinal direction parallel to the Y direction and its short direction (width direction) parallel to the X direction. The length L _a in the longitudinal direction (Y direction) of each mesh wiring layer 20 can be selected, for example, in the range of 1 mm or more and 100 mm or less, and the width W _a in the lateral direction (X direction) of each mesh wiring layer 20 can be selected, for example, in the range of 1 mm or more and 25 mm or less. In particular, the mesh wiring layer 20 may be a millimeter wave antenna. When the mesh wiring layer 20 is a millimeter wave antenna, the length L _a of the mesh wiring layer 20 can be selected in the range of 1 mm or more and 10 mm or less, more preferably 1.5 mm or more and 5 mm or less.

The mesh wiring layer 20 has metal wires formed in a grid shape or mesh shape, and has a uniform repeating pattern in the X direction and the Y direction. That is, as shown in FIG. 2, the mesh wiring layer 20 is an L-shaped unit pattern composed of a portion (second direction wiring 22) extending in the X direction and a portion (first direction wiring 21) extending in the Y direction. It consists of repetitions of the shape 20a (shaded portion in FIG. 2).

As shown in FIG. 2 , each mesh wiring layer 20 includes a plurality of first directional wirings (antenna wirings (wirings)) 21 functioning as antennas and a plurality of second wirings connecting the plurality of first directional wirings 21 . and a directional wire 22 . Specifically, the plurality of first directional wirings 21 and the plurality of second directional wirings 22 are integrated as a whole to form a regular lattice shape or mesh shape. Each first directional wiring 21 extends in a direction (Y direction) corresponding to the frequency band of the antenna, and each second directional wiring 22 extends in a direction (X direction) orthogonal to the first directional wiring 21. . The first directional wiring 21 has a length L _a corresponding to a predetermined frequency band (the length of the mesh wiring layer 20 described above, see FIG. 1), so that it mainly functions as an antenna. On the other hand, the second directional wiring 22 connects the first directional wirings 21 to each other, so that the first directional wiring 21 may be disconnected or the first directional wiring 21 and the power supply section 40 may not be electrically connected. It plays a role in suppressing troubles that occur.

In each mesh wiring layer 20, a plurality of openings 23 are formed by being surrounded by mutually adjacent first directional wirings 21 and mutually adjacent second directional wirings 22. As shown in FIG. Also, the first directional wiring 21 and the second directional wiring 22 are arranged at regular intervals. That is, the plurality of first direction wirings 21 are arranged at regular intervals, and the pitch P ₁ (see FIG. 2) can be in the range of, for example, 0.01 mm or more and 1 mm or less. Also, the plurality of second-direction wirings 22 are arranged at regular intervals, and the pitch P ₂ (see FIG. 2) can be in the range of, for example, 0.01 mm or more and 1 mm or less. By arranging the plurality of first directional wirings 21 and the plurality of second directional wirings 22 at equal intervals in this way, the size of the openings 23 in each mesh wiring layer 20 is uniform. The mesh wiring layer 20 can be made difficult to visually recognize with the naked eye. Also, the pitch P1 of the _first directional wirings 21 is equal to the pitch P2 of the _second directional wirings 22 . Therefore, each opening 23 has a substantially square shape in plan view, and the transparent substrate 11 is exposed from each opening 23 . Therefore, by increasing the area of each opening 23, the transparency of the wiring board 10 as a whole can be improved. In addition, the length L ₃ (see FIG. 2) of one side of each opening 23 can be in the range of, for example, 0.01 mm or more and 1 mm or less. The first direction wirings 21 and the second direction wirings 22 are orthogonal to each other, but are not limited to this, and may cross each other at an acute or obtuse angle. The shape of the openings 23 is preferably the same shape and size over the entire surface, but may not be uniform over the entire surface, such as by changing the shape depending on the location.

As shown in FIG. 3, each first direction wiring 21 has a substantially rectangular or square cross section perpendicular to its longitudinal direction (X direction cross section). In this case, the cross-sectional shape of the first directional wiring 21 is substantially uniform along the longitudinal direction (Y direction) of the first directional wiring 21 . Further, as shown in FIG. 4, the shape of the cross section (Y direction cross section) perpendicular to the longitudinal direction of each second direction wiring 22 is substantially rectangular or substantially square. (X-direction cross section) It is substantially the same as the shape. In this case, the cross-sectional shape of the second directional wiring 22 is substantially uniform along the longitudinal direction (X direction) of the second directional wiring 22 . The cross-sectional shapes of the first direction wiring 21 and the second direction wiring 22 may not necessarily be substantially rectangular or substantially square. It may have a narrow trapezoidal shape or a shape with curved side surfaces located on both sides in the width direction.

In the present embodiment, the line width W ₁ (length in the X direction, see FIG. 3) of the first directional wiring 21 and the line width W ₂ (length in the Y direction, see FIG. 4) of the second directional wiring 22 are , is not particularly limited, and can be appropriately selected depending on the application. For example, the line width W1 of the _first direction wiring 21 can be selected in the range of 0.1 μm to 5.0 μm, and the line width W2 of the _second direction wiring 22 can be selected in the range of 0.1 μm to 5.0 μm. can be selected in the range of Moreover, the height H ₁ (the length in the Z direction, see FIG. 3) of the first directional wiring 21 and the height H ₂ (the length in the Z direction, see FIG. 4) of the second directional wiring 22 are not particularly limited. , can be appropriately selected according to the application, for example, it can be selected in the range of 0.1 μm or more and 5.0 μm or less.

The material of the first direction wiring 21 and the second direction wiring 22 may be a metal material having conductivity. Although the material of the first direction wiring 21 and the second direction wiring 22 is copper in the present embodiment, the material is not limited to this. As materials for the first direction wiring 21 and the second direction wiring 22, for example, metal materials (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used.

In the present embodiment, the overall aperture ratio of mesh wiring layer 20 can be, for example, in the range of 87% or more and less than 100%. By setting the overall aperture ratio of the mesh wiring layer 20 within this range, the conductivity and transparency of the wiring substrate 10 can be ensured. Note that the aperture ratio is defined as a unit area of a predetermined region (for example, a part of the mesh wiring layer 20) in which there is no metal portion such as the opening region (the first direction wiring 21, the second direction wiring 22, etc.) and the substrate 11 exposed) area ratio (%).

Referring to FIG. 1 again, the power supply section 40 is electrically connected to each mesh wiring layer 20 . The power supply portion 40 is made of a substantially rectangular conductive thin plate-like member. The longitudinal direction of the power supply portion 40 is parallel to the X direction, and the short direction of the power supply portion 40 is parallel to the Y direction. In addition, the power supply unit 40 is arranged at the longitudinal end of the substrate 11 (Y-direction minus side end). As the material of the power supply unit 40, for example, metal materials (including alloys) such as gold, silver, copper, platinum, tin, aluminum, iron, and nickel can be used. The power supply unit 40 is electrically connected to the wireless communication circuit 92 of the image display device 90 via the power supply line 95 when the wiring board 10 is incorporated in the image display device 90 (see FIG. 5). Although the power supply section 40 is provided on the surface of the substrate 11 , the power supply section 40 is not limited to this, and part or all of the power supply section 40 may be positioned outside the peripheral edge of the substrate 11 .

As shown in FIG. 2, the plurality of first-direction wirings 21 are electrically connected to the power feeder 40 on the negative side in the Y direction. In this case, the power supply section 40 is formed integrally with the mesh wiring layer 20 . The thickness T ₃ (see FIG. 4) of the feeding portion 40 should be the same as the height H ₁ (see FIG. 3) of the first directional wiring 21 and the height H ₂ (see FIG. 4) of the second directional wiring 22. can be selected in the range of, for example, 0.1 μm or more and 5.0 μm or less.

Furthermore, as shown in FIGS. 3 and 4 , a protective layer 17 is formed on the surface of the substrate 11 so as to cover the mesh wiring layer 20 and the power supply section 40 . The protective layer 17 protects the mesh wiring layer 20 and the power supply section 40 and may be formed over substantially the entire surface of the substrate 11 .

In the present embodiment, the thickness T ₂ (see FIG. 3) of protective layer 17 is 0.05 μm or more and 1.8 μm or less. When the thickness T2 of the protective layer 17 is 0.05 μm or _more , the abrasion resistance and weather resistance of the protective layer 17 can be enhanced. _In addition, since the thickness T2 of the protective layer 17 is 1.8 μm or less, when the conductive particles 95d of the anisotropic conductive film (ACF) 95c described later enter the protective layer 17, the conductive particles 95d are It is possible to facilitate contact with the power supply unit 40 . Therefore, it is possible to ensure electrical connection between the power supply unit 40 and the power supply line 95 (see FIG. 5). In this specification, the thickness T2 of the protective layer 17 refers to the Z _- direction distance from the surface of the power supply portion 40 to the surface of the protective layer 17 .

Moreover, the pencil hardness of the surface of the protective layer 17 is B or more and 2H or less. When the pencil hardness of the surface of the protective layer 17 is B or higher, the abrasion resistance and weather resistance of the protective layer 17 can be enhanced. Further, since the pencil hardness of the surface of the protective layer 17 is 2H or less, the conductive particles 95d of the anisotropic conductive film (ACF) 95c, which will be described later, can easily enter the protective layer 17. , the electrical connectivity with the feed line 95 can be improved. The pencil hardness can be measured according to the pencil hardness test specified in JISK5600-5-4:1999.

Furthermore, the dielectric loss tangent of the protective layer 17 is 0.005 or less. As a result, it is possible to effectively prevent the protective layer 17 from affecting transmission and reception of radio waves in the mesh wiring layer 20 . Therefore, it is possible to prevent the antenna performance from deteriorating. The dielectric loss tangent of the protective layer 17 can be measured according to IEC 62562 or ASTM D150 by a method similar to the method for measuring the dielectric constant of the substrate 11 .

Examples of materials for the protective layer 17 include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate, modified resins and copolymers thereof, polyester resins, polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, and the like. Colorless and transparent insulating resins such as polyvinyl resins and their copolymers, polyurethane resins, epoxy resins, polyamide resins, and chlorinated polyolefins can be used.

Protective layer 17 preferably contains acrylic resin or polyester resin. As a result, the adhesion between the first directional wiring 21 and the second directional wiring 22 and the substrate 11 can be further improved, and the abrasion resistance and weather resistance of the first directional wiring 21 and the second directional wiring 22 can be improved. can be higher. Furthermore, invisibility can be maintained and antenna performance can be maintained.

Furthermore, the protective layer 17 preferably contains silicon dioxide. Silicon dioxide may be added to the resin as a powder. Alternatively, a film substantially free of resin may be formed by a method such as vapor deposition, sputtering, or CVD. Thereby, the slip property of the surface of the protective layer 17 and the antireflection property of the protective layer 17 can be improved.

Here, as shown in FIG. 5, the wiring board 10 according to the present embodiment is incorporated into an image display device 90 having a display 91. As shown in FIG. The wiring board 10 is arranged on the display 91 . Examples of such an image display device 90 include mobile terminal devices such as smartphones and tablets. The mesh wiring layer 20 of the wiring board 10 is electrically connected to the wireless communication circuit 92 of the image display device 90 via the power supply section 40 and the power supply line 95 . In this manner, radio waves of a predetermined frequency can be transmitted and received via the mesh wiring layer 20, and communication can be performed using the image display device 90. FIG.

The power supply line 95 that electrically connects the power supply unit 40 and the wireless communication circuit 92 may be, for example, a flexible printed circuit board. As shown in FIG. 6, the feeder line 95 has a base material 95a and a metal wiring portion 95b laminated on the base material 95a. Among them, the base material 95a may contain, for example, a resin material such as polyimide or a liquid crystal polymer. Moreover, the metal wiring part 95b may contain copper, for example. The metal wiring portion 95b is electrically connected to the power supply portion 40 via conductive particles 95d, which will be described later. 6, illustration of the display 91 is omitted.

Such a feeder line 95 is pressure-bonded to the wiring board 10 via an anisotropic conductive film (ACF) 95c. The anisotropic conductive film 95c contains a resin material such as acrylic resin or epoxy resin, and conductive particles 95d. Further, the anisotropic conductive film 95c is arranged so as to face the power feeding section 40. As shown in FIG. At this time, the conductive particles 95d of the anisotropic conductive film 95c break through the surface of the protective layer 17 and enter the protective layer 17 when the power supply line 95 is pressure-bonded to the wiring board 10 . A portion of the conductive particles 95 d is in contact with the power feeding section 40 . Thus, the power supply line 95 is electrically connected to the power supply section 40 by the conductive particles 95d entering the protective layer 17 . Part of the anisotropic conductive film 95c may be eluted around the power supply line 95 when the power supply line 95 is pressure-bonded to the wiring board 10 . Also, the particle size of the conductive particles 95d may be, for example, about 7 μm. This embodiment also provides a module 90A that includes a wiring board 10 and a feeder line 95 crimped to the wiring board 10 via an anisotropic conductive film 95c containing conductive particles 95d.

[Method for manufacturing wiring board]
Next, with reference to FIGS. 7A to 7F, a method for manufacturing a wiring board according to this embodiment will be described. 7A to 7F are cross-sectional views showing the method of manufacturing the wiring board according to this embodiment.

First, a transparent substrate 11 is prepared.

Next, as shown in FIG. 7A, a mesh wiring layer 20 including a plurality of first direction wirings 21 and a power supply section 40 electrically connected to the mesh wiring layer 20 are formed on the substrate 11. do. At this time, first, the metal foil 51 is laminated over substantially the entire surface of the substrate 11 . In the present embodiment, metal foil 51 may have a thickness of 0.1 μm or more and 5.0 μm or less. In the present embodiment, metal foil 51 may contain copper.

Next, as shown in FIG. 7B, a photo-curing insulating resist 52 is supplied over substantially the entire surface of the metal foil 51 . Examples of the photocurable insulating resist 52 include organic resins such as acrylic resins and epoxy resins.

Subsequently, as shown in FIG. 7C, an insulating layer 54 is formed by photolithography. In this case, the photocurable insulating resist 52 is patterned by photolithography to form an insulating layer 54 (resist pattern). At this time, the insulating layer 54 is formed so that the metal foil 51 corresponding to the first directional wiring 21 and the second directional wiring 22 is exposed.

Next, as shown in FIG. 7D, the metal foil 51 on the surface of the substrate 11 is removed. At this time, wet treatment is performed using ferric chloride, cupric chloride, strong acids such as sulfuric acid and hydrochloric acid, persulfate, hydrogen peroxide, aqueous solutions thereof, or a combination of the above. The metal foil 51 is etched so that the surface is exposed.

Subsequently, as shown in FIG. 7E, the insulating layer 54 is removed. In this case, the insulating layer 54 on the metal foil 51 is removed by wet treatment using a permanganate solution, N-methyl-2-pyrrolidone, an acid or alkaline solution, or the like, or dry treatment using oxygen plasma. Remove.

As another method for manufacturing the wiring board 10, the following method called a so-called lift-off method can be used. In this case, first, the photocurable insulating resist 52 is supplied over substantially the entire surface of the substrate 11 . Next, the photocurable insulating resist 52 is patterned by photolithography to form an insulating layer 54 (resist pattern). Subsequently, the metal foil 51 is laminated on substantially the entire surface of the insulating layer 54 and the surface of the substrate 11 exposed from the insulating layer 54 . After that, by removing the insulating layer 54, the metal foil 51 formed on the substrate 11 remains in a pattern.

Thus, the mesh wiring layer 20 arranged on the substrate 11 is obtained. In this case, the mesh wiring layer 20 includes first direction wirings 21 and second direction wirings 22 . At this time, the power supply portion 40 may be formed by part of the metal foil. Alternatively, a plate-shaped power supply portion 40 may be separately prepared and electrically connected to the mesh wiring layer 20 .

After that, as shown in FIG. 7( f ), a protective layer 17 is formed on the substrate 11 so as to cover the mesh wiring layer 20 and the power supply section 40 . At this time, the protective layer 17 is formed so that the thickness T2 of the protective layer 17 is 0.05 μm or _more and 1.8 μm or less, and the pencil hardness of the surface of the protective layer 17 is B or more and 2H or less. Methods for forming the protective layer 17 include roll coating, gravure coating, gravure reverse coating, micro gravure coating, slot die coating, die coating, knife coating, inkjet coating, dispenser coating, kiss coating, spray coating, screen printing, offset printing, and flexographic coating. Printing may be used.

In this manner, the substrate 11, the mesh wiring layer 20 arranged on the substrate 11, the power supply part 40 electrically connected to the mesh wiring layer 20, the mesh wiring layer 20 and the mesh wiring layer 20 arranged on the substrate 11 A wiring board 10 including a protective layer 17 covering the power feeding portion 40 is obtained.

[Module manufacturing method]
Next, with reference to FIGS. 8(a) to 8(c), a module manufacturing method according to the present embodiment will be described. 8(a)-(c) are cross-sectional views showing the method of manufacturing the module according to the present embodiment.

First, as shown in FIG. 8A, a wiring substrate 10 is prepared. At this time, the wiring substrate 10 is manufactured by the method shown in FIGS. 7(a) to 7(f), for example.

Next, the power supply line 95 is pressure-bonded to the wiring board 10 via the anisotropic conductive film 95c containing the conductive particles 95d. At this time, first, an anisotropic conductive film 95c is arranged on the wiring substrate 10 as shown in FIG. 8B. At this time, the anisotropic conductive film 95c is arranged so as to face the power feeding section 40 .

Next, as shown in FIG. 8(c), the power supply line 95 is pressure-bonded to the wiring board 10. Then, as shown in FIG. At this time, by applying pressure and heat to the power supply line 95 , the power supply line 95 is pressure-bonded to the wiring substrate 10 . At this time, the conductive particles 95 d of the anisotropic conductive film 95 c break through the surface of the protective layer 17 and enter the protective layer 17 . A portion of the conductive particles 95 d contacts the power feeding portion 40 . As the conductive particles 95 d enter the protective layer 17 in this way, the feed line 95 is electrically connected to the feed section 40 .

[Action of the present embodiment]
Next, the operation of the wiring board having such a configuration will be described.

As described above, the wiring board 10 is incorporated into the image display device 90 having the display 91 (see FIG. 5). In this manner, radio waves of a predetermined frequency can be transmitted and received via the mesh wiring layer 20, and communication can be performed using the image display device 90. FIG.

By the way, in general, when the power supply unit 40 is covered with the protective layer 17 in order to protect the power supply unit 40, the power supply line 95 for connecting the wiring substrate 10 to the wireless communication circuit 92 of the image display device 90 and the , the electrical connection with the power supply unit 40 may become unstable.

In contrast, according to the present embodiment, the thickness T2 of the protective layer 17 is 0.05 μm or _more and 1.8 μm or less, and the pencil hardness of the surface of the protective layer 17 is B or more and 2H or less. This allows the conductive particles 95d of the anisotropic conductive film 95c to enter the protective layer 17, and when the conductive particles 95d enter the protective layer 17, the conductive particles 95d come into contact with the power supply section 40. can be made easier. Therefore, the electrical connectivity between the power feeding section 40 and the power feeding line 95 can be improved. In addition, the abrasion resistance and weather resistance of the protective layer 17 can be enhanced.

The wiring substrate 10 includes a substrate 11 and a mesh wiring layer 20 disposed on the substrate 11 and including a plurality of first direction wirings 21. The substrate 11 has a transmittance of light having a wavelength of 400 nm or more and 700 nm or less. Since it is 85% or more, the transparency of the wiring board 10 is ensured. Accordingly, when the wiring board 10 is arranged on the display 91, the display 91 can be viewed through the opening 23 of the mesh wiring layer 20, and the visibility of the display 91 is not hindered.

Further, according to the present embodiment, the dielectric loss tangent of protective layer 17 is 0.005 or less. As a result, it is possible to effectively prevent the protective layer 17 from affecting transmission and reception of radio waves in the mesh wiring layer 20 . Therefore, it is possible to prevent the antenna performance from deteriorating.

Furthermore, according to the present embodiment, protective layer 17 contains silicon dioxide. Thereby, the slip property of the surface of the protective layer 17 and the antireflection property of the protective layer 17 can be improved.

(Modification)
Next, a modification of the wiring board according to the present embodiment will be described with reference to FIG. The modification shown in FIG. 9 is different in the configuration of the mesh wiring layer 20, and other configurations are substantially the same as the embodiment shown in FIGS. 1 to 8 described above. In FIG. 9, the same parts as those shown in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 9 is an enlarged plan view showing a mesh wiring layer 20 according to one modification. In FIG. 9, the first directional wiring 21 and the second directional wiring 22 intersect obliquely (non-perpendicularly), and each opening 23 is formed in a diamond shape in plan view. The first directional wiring 21 and the second directional wiring 22 are parallel to neither the X direction nor the Y direction, respectively, but either the first directional wiring 21 or the second directional wiring 22 is parallel to the X direction or the Y direction. may be parallel to

[Example]
Next, a specific example of this embodiment will be described.

(Example 1)
A module having the configuration shown in FIG. 6 was produced. In this case, a substrate made of polyethylene terephthalate having a thickness of 100 μm was used as the substrate of the wiring substrate. As the first direction wiring and the second direction wiring, copper wiring having a line width of 1 μm and a height of 1 μm was formed on a substrate made of polyethylene terephthalate. Furthermore, as a protective layer, a transfer hard coat (HC) agent (product name: PA-1000, manufactured by Showa Denko Materials) was formed on the polyethylene terephthalate substrate and the copper wiring. The thickness of the protective layer was 1.0 μm. After that, the power supply line was crimped to the wiring board.

(1) Pencil hardness measurement test Next, a pencil hardness measurement test was conducted to measure the pencil hardness of the surface of the protective layer 17 . At this time, the pencil hardness of the protective layer was measured according to the pencil hardness test specified in JISK5600-5-4:1999.

(2) Connectivity Evaluation Next, the electrical connectivity between the power supply portion of the wiring board and the power supply line was confirmed.

(3) Scratch resistance test Next, a scratch resistance test was conducted. At this time, first, a jig to which 100 g of steel wool was attached was prepared. Next, steel wool was rubbed against the protective layer to confirm whether or not disconnection had occurred in the copper wiring. At this time, when the steel wool was rubbed against the protective layer, the jig was moved so that the moving distance of the steel wool was about 2 cm to about 5 cm in both directions. Then, the steel wool was reciprocated 10 times.

(Example 2)
As the protective layer, an acrylic resin dissolved in an organic solvent was formed on the polyethylene terephthalate substrate and the copper wiring, and the thickness of the protective layer was 0.1 μm. Then, a module was prepared, and a pencil hardness measurement test, connectivity evaluation, and scratch resistance test were conducted.

(Example 3)
A module was produced in the same manner as in Example 2, except that the thickness of the protective layer was 1.5 μm, and the pencil hardness measurement test, connectivity evaluation, and scratch resistance test were performed.

(Comparative example 1)
A module was produced in the same manner as in Example 1, except that the thickness of the protective layer was 4.0 μm, and a pencil hardness measurement test, connectivity evaluation, and scratch resistance test were performed.

(Comparative example 2)
A module was produced in the same manner as in Example 2, except that the thickness of the protective layer was 2.1 μm, and the pencil hardness measurement test, connectivity evaluation, and scratch resistance test were performed.

(Comparative Example 3)
A module was produced in the same manner as in Example 3, except that the thickness of the protective layer was 0.03 μm, and a pencil hardness measurement test, connectivity evaluation, and scratch resistance test were performed.

Table 1 shows the above results. In the table below, "○" means that the result was good (good), and "x" means that the result was not good (poor).

As a result, as shown in Table 1, the modules according to Comparative Examples 1 and 2 did not have good electrical connectivity between the power supply portion of the wiring board and the power supply line.

On the other hand, in the modules according to Examples 1 to 3, the electrical connectivity between the power supply portion of the wiring board and the power supply line was good. Therefore, it was found that the module according to the present embodiment can improve the electrical connectivity between the power supply portion of the wiring board and the power supply line.

Further, as shown in Table 1, the module according to Comparative Example 3 did not have good scratch resistance, and one or more disconnections occurred in the copper wiring.

On the other hand, the modules according to Examples 1 to 3 had good scratch resistance, and no breakage occurred in the copper wiring. Therefore, it was found that the module according to this embodiment can improve the scratch resistance.

It is also possible to appropriately combine a plurality of constituent elements disclosed in the above embodiments and modifications as necessary. Alternatively, some components may be deleted from all the components shown in the above embodiments and modifications.

REFERENCE SIGNS LIST 10 Wiring board 11 Substrate 17 Protective layer 20 Mesh wiring layer 21 First direction wiring 40 Feeding part 95 Feeding line 95c Anisotropic conductive film 95d Conductive particles 90A Module

Claims (8)

A wiring board,
a substrate;
a mesh wiring layer disposed on the substrate and including a plurality of wiring;
a power supply unit electrically connected to the mesh wiring layer;
a protective layer disposed on the substrate and covering the mesh wiring layer and the power feeding portion;
The substrate has a transmittance of 85% or more for light with a wavelength of 400 nm or more and 700 nm or less,
The thickness of the protective layer is 0.05 μm or more and 1.8 μm or less,
The wiring board, wherein the surface of the protective layer has a pencil hardness of B or more and 2H or less. 2. The wiring board according to claim 1, wherein the protective layer has a dielectric loss tangent of 0.005 or less. 3. The wiring board according to claim 1, wherein said protective layer contains acrylic resin or polyester resin. 4. The wiring substrate according to claim 1, wherein said protective layer contains silicon dioxide. 5. The wiring board according to claim 1, having a radio wave transmission/reception function. A wiring board according to any one of claims 1 to 5;
a power supply line crimped to the wiring board via an anisotropic conductive film containing conductive particles;
The anisotropic conductive film is arranged to face the power supply unit,
The module, wherein the power supply line is electrically connected to the power supply section by the conductive particles entering the protective layer. A method for manufacturing a wiring board,
preparing a substrate;
forming, on the substrate, a mesh wiring layer including a plurality of wirings, and a power supply section electrically connected to the mesh wiring layer;
forming a protective layer on the substrate so as to cover the mesh wiring layer and the power supply section;
The substrate has a transmittance of 85% or more for light with a wavelength of 400 nm or more and 700 nm or less,
The thickness of the protective layer is 0.05 μm or more and 1.8 μm or less,
The method for manufacturing a wiring board, wherein the surface of the protective layer has a pencil hardness of B or more and 2H or less. A method of manufacturing a module, comprising:
A step of preparing a wiring board according to any one of claims 1 to 5;
A step of crimping a power supply line to the wiring board via an anisotropic conductive film containing conductive particles;
The anisotropic conductive film is arranged to face the power supply unit,
The method of manufacturing a module, wherein the power supply line is electrically connected to the power supply section by the conductive particles entering the protective layer.

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