JP7634564B2 - Conductive films and electronic devices - Google Patents

Description

The present invention relates to a conductive film and an electronic device comprising the same.

In electronic devices such as liquid crystal display devices, a planar antenna having a conductor wiring with a predetermined pattern as a radiating element may be provided (for example, Patent Document 1).

JP 2000-138512 A

The present invention provides a conductive film having a conductor portion including a wiring portion having a mesh-like pattern and a terminal portion, and the conductor portion can be easily formed with high precision.

One aspect of the present invention provides a conductive film comprising a film-like substrate and a conductor portion extending on a main surface of the substrate. The conductor portion includes a wiring portion having a mesh-like pattern including a plurality of linear portions, and a terminal portion.

The terminal portion may have a portion having a pattern including a plurality of openings, and the conductive film may further include a resin portion filling the plurality of openings in the terminal portion. Alternatively, the terminal portion may have a ground terminal that is a portion having a pattern including a plurality of openings.

Conventionally, terminal portions connected to wiring portions having a mesh-like pattern have a form without openings and are provided in a predetermined region. However, when a terminal portion without openings is formed in the same manner as a wiring portion having a mesh-like pattern, it may be difficult to ensure high precision because of the large difference in width between the two. In contrast, when the terminal portion has a portion having a pattern including multiple openings as in the present invention, the wiring portion and the terminal portion can be easily formed efficiently with high precision, for example, by a method including pattern formation by imprinting. A conductive film having a resin portion that fills the openings is particularly easy to manufacture by a method including pattern formation by imprinting.

The wiring portion may include a radiating element of an antenna. A conductive film including a radiating element of an antenna may be used as a planar transparent antenna.

The conductive film may further include a resin portion that fills the opening of the wiring portion. A conductive film that includes a resin portion that fills the opening of the wiring portion is particularly easy to manufacture by a method that includes pattern formation by imprinting.

The pattern including the plurality of openings in the terminal portion may be a mesh-like pattern including a plurality of linear portions. A terminal portion having a mesh-like pattern is particularly easy to manufacture by a method including pattern formation by imprinting.

The width of the linear portion in the terminal portion may be greater than the width of the linear portion in the wiring portion. When the width of the linear portion constituting the terminal portion is relatively large, the terminal portion is more likely to function satisfactorily.

The width of the linear portion in the terminal portion may be 200 μm or less. When the width of the linear portion constituting the terminal portion is small, it is easy to form the terminal portion with particularly high precision by a method including pattern formation by imprinting, while avoiding the generation of resin residue in the area where the linear portion is formed.

The terminal portion may further include a power supply terminal. The power supply terminal may be provided so as to cover the entire area surrounded by a single closed line on the main surface of the substrate at a position away from the portion having the pattern including the plurality of openings. This power supply terminal can be used to supply a voltage necessary for the conductive film to function as, for example, an antenna.

When viewed from a direction perpendicular to the main surface of the substrate, the area of the region enclosed by the outline of the portion of the terminal portion having a pattern including the plurality of openings may be larger than the area of the power supply terminal. For example, in the case of a ground terminal, a larger area enclosed by the outline is more likely to provide good performance even if the terminal has openings.

The width of the linear portion at the terminal portion may be smaller than the minimum width of the power supply terminal.

Another aspect of the present invention provides an electronic device comprising the above-mentioned conductive film.

The conductive film according to one aspect of the present invention has a conductor portion including a wiring portion having a mesh-like pattern and a terminal portion, and the conductor portion can be easily formed with high precision.

FIG. 1 is a plan view illustrating an embodiment of a conductive film. FIG. 1 is a cross-sectional view showing one embodiment of a conductive film. 1A to 1C are process diagrams illustrating an example of a method for producing a conductive film. 1A to 1C are process diagrams illustrating an example of a method for producing a conductive film. FIG. 1 is a plan view illustrating an embodiment of a conductive film. FIG. 2 is an enlarged cross-sectional view showing a portion of the conductive film.

Several embodiments of the present invention are described in detail below. However, the present invention is not limited to the following embodiments.

Figure 1 is a plan view showing one embodiment of a conductive film. Figure 2 is a cross-sectional view showing one embodiment of a conductive film. Figure 2 is a cross-sectional view corresponding to a portion of the conductive film in Figure 1.

1 and 2 comprises a film-like substrate 1 and a conductor portion 2 extending on a main surface 1S of the substrate 1. The substrate 1 is omitted in FIG. 1. The conductor portion 2 includes a wiring portion 5 having a mesh-like pattern including a plurality of linear portions, and a terminal portion 6 connected to the wiring portion 5. The terminal portion 6 has a ground terminal 3 and a power supply terminal 8. The conductor portion 2 does not need to extend over the entire main surface 1S of the substrate 1, and the conductor portion 2 may be provided on a partial region of the main surface 1S.

The ground terminal 3 is a portion of the terminal portion 6 having a pattern including a plurality of openings 3a through which the main surface 1S of the substrate 1 is exposed. The pattern including the plurality of openings 3a may be a mesh-like pattern including a plurality of regularly arranged openings 3a formed by a plurality of linear portions intersecting each other. In an electronic device in which the conductive film 20 is incorporated, a ground potential is usually supplied to the ground terminal 3. The conductive film 20 illustrated in FIG. 1 and FIG. 2 has two ground terminals 3, but the number of ground terminals 3 that one conductive film 20 has is not limited to two and may be, for example, one or two. When the wiring portion 5 has a plurality of antenna radiating elements, the number of ground terminals per radiating element may be one or two.

A resin portion 7A is provided to fill the multiple openings 3a in the terminal portion 6 (or the ground terminal 3). A resin portion 7B is also provided to fill the openings 5a formed by the mesh pattern of the wiring portion 5.

The width W3 of the linear portion in the ground terminal 3 may be 200 μm or less. If the width W3 of the linear portion is relatively small, it is easy to form the terminal portion with particularly high precision, while avoiding the generation of resin residue in the area where the linear portion is formed, for example, by a method including pattern formation by imprinting, which will be described later. It is desirable that the ground terminal is provided over a relatively large area, but forming a terminal portion without an opening in a large area is likely to cause the generation of resin residue in the imprinting method. From the same viewpoint, the width W3 of the linear portion in the ground terminal 3 may be 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less. In order to maintain good function as a ground terminal, the width W3 of the linear portion in the ground terminal 3 may be larger than the width W5 of the linear portion constituting the mesh-like pattern of the wiring portion 5. For example, the width ratio W3/W5 may be 50 or more, or 400 or less. The width W3 of the linear portion of the ground terminal 3 may be, for example, 5 μm or more. In this specification, the “width of the linear portion” means the maximum width of the linear portion in a direction perpendicular to the longitudinal direction of the linear portion and parallel to the main surface 1S of the substrate 1.

The mesh pattern of the ground terminal 3 may include a plurality of first linear portions arranged parallel to each other and a plurality of second linear portions arranged parallel to each other. The angle between the first linear portion and the second linear portion, i.e., the smaller of the two pairs of interior angles in the opening 3a of the parallelogram or rhombus formed by the mesh pattern, may be, for example, 10 to 90 degrees or 10 to 45 degrees. The portion of the terminal portion 6 having a pattern including a plurality of openings 3a, i.e., the ground terminal 3, may further include linear portions along the ends of the ground terminal 3 in addition to the first linear portions and the second linear portions.

The power supply terminal 8 is provided at a position away from the portion of the terminal portion 6 having a pattern including a plurality of openings 3a (ground terminal 3) so as to cover the entire area enclosed by a single closed line on the main surface 1S of the substrate 1. In other words, the power supply terminal 8 has a solid form that does not include any openings, and is provided on the main surface 1S of the substrate 1. The fact that the power supply terminal 8 has a solid form is advantageous in terms of efficient power supply to the wiring portion 5.

The power supply terminal may be provided separately from the conductor portion extending on the main surface of the substrate. For example, the power supply terminal may extend in a plane so as to cover a terminal portion that is a part of the conductor portion having a pattern including an opening. FIG. 5 is a plan view showing an example of a conductive film having such a power supply terminal. FIG. 6 is an enlarged cross-sectional view showing a portion of the conductive film 20 in FIG. 5 where the power supply terminal 8' is provided. The conductive film 20 illustrated in FIG. 5 and FIG. 6 has a terminal portion 6 composed of a ground terminal 3 that is a part of the conductor portion 2 having a pattern including an opening, and a terminal pattern portion 80 that is a part of the conductor portion 2 having a pattern including an opening and is provided at a position away from the ground terminal 3. The terminal pattern portion 80 is a portion of the conductor portion 2 that extends toward the outside of the wiring portion 5. A part of the terminal pattern portion 80 is covered by the power supply terminal 8'. The power supply terminal 8' is a conductor layer having a solid form. In a plan view, the outer edge of the power supply terminal 8' may be located inside the outer edge of the terminal pattern portion 80 (conductor portion 2). In this case, the outer edge of the power supply terminal 8' is prevented from protruding beyond the outer edge of the conductor portion 2, thereby preventing the wiring portion 5 from shorting out with another terminal portion adjacent to the terminal portion 6. In addition, it is possible to prevent the power supply terminal 8' from protruding toward the electrode side, thereby preventing the visibility of the conductive film from improving. The terminal pattern portion 80 (conductor portion 2) covered by the power supply terminal 8' may have a mesh-like pattern similar to that of the wiring portion 5 (conductor portion 2) that is not covered by the power supply terminal 8'.

A resin portion 7B is also provided to fill the opening 5a formed by the mesh pattern of the wiring portion 5. The power supply terminal 8' shown in Figures 5 and 6 is formed to cover the surface of the conductor portion 2 (or the wiring portion 5) and the surface of the resin portion 7A that fills the opening of the conductor portion 2. In the example shown in Figures 5 and 6, the power supply terminal 8' is integrally formed without gaps in the area surrounded by its outer edge. The power supply terminal 8' may be divided into multiple areas, and the wiring portion 5 and the resin portion 7B may be exposed in a slit shape between the divided areas.

As shown in the cross-sectional view of FIG. 6, the height of the wiring portion 5 (conductor portion 2) covered by the power supply terminal 8' from the main surface 1S of the substrate 1 may be greater than the height of the resin portion 7A from the main surface 1S. The surface 8'S of the power supply terminal 8' opposite the wiring portion 5 (conductor portion 2) may be roughened. In other words, the surface roughness of the surface 8'S may be greater than the surface roughness of the wiring portion 5 (conductor portion 2). If the surface 8'S is roughened, the connection strength with an external connection terminal may be improved. The surface roughness here may be, for example, the arithmetic mean roughness Ra. The thickness of the power supply terminal 8' may be greater than the thickness of the wiring portion 5 (conductor portion 2).

When viewed from a direction perpendicular to the main surface 1S of the substrate 1, the width W3 of the linear portion of the ground terminal 3 is smaller than the minimum width W8 of the power supply terminal 8 or the minimum width W8' of the power supply terminal 8'. For example, the width ratio W3/W8 or W3/W8' may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, or 0.5 or less, or may be 0.25 or more. When the power supply terminals 8, 8' have a rectangular main surface, such as the conductive film 20 illustrated in Figures 1, 2, 3, 4, 5, and 6, the length of the short side of the rectangle corresponds to the minimum width W8, W8'.

When viewed from a direction perpendicular to the main surface 1S of the substrate 1, the area of the region surrounded by the outline of the portion of the terminal portion 6 having a pattern including a plurality of openings 3a (ground terminal 3) (hereinafter also simply referred to as the "area of the ground terminal 3") may be larger than the area of the power supply terminal 8 or power supply terminal 8'. The larger the area of the ground terminal 3, the more likely it is that the better the performance of the ground terminal will be. The ratio of the area of the ground terminal 3 to the area of the power supply terminal 8 or power supply terminal 8' may be 2.0 or more, or 3.0 or more, or may be 10 or less. When two or more ground terminals 3, power supply terminals 8, 8', or both are provided on one conductive film 20, the ratio of their total areas may be within the above range.

The ground terminal may be provided separately from the conductor portion extending on the main surface of the substrate. For example, the ground terminal may be a conductor layer extending in a plane so as to cover the terminal pattern portion as a terminal portion having a pattern including an opening, and having a solid form. In this case, in a planar view, the outer edge of the ground terminal may be located inside the outer edge of the terminal pattern portion (terminal portion, conductor portion) located below it. This prevents the ground terminal from protruding from the outer edge of the conductor portion, thereby preventing the ground terminal from shorting with other adjacent terminal portions. In addition, it is possible to prevent the ground terminal from protruding to the electrode side, thereby improving the visibility of the conductor portion. The terminal pattern portion covered by the ground terminal having a solid form may have a mesh-like pattern similar to the conductor portion of the portion not covered by the ground terminal. The conductive film may have a power supply terminal having a solid form covering the terminal portion (terminal pattern portion), a ground terminal having a solid form covering the terminal portion (terminal pattern portion), or both of these, as described above.

The wiring section 5 includes a radiating element including a mesh-like pattern composed of a plurality of intersecting linear portions. The width of the linear portions constituting the wiring section 5 may be, for example, 0.5 μm or more, 1 μm or more, or 2 μm or more, or may be 5 μm or less, 2 μm or less, or 1 μm or less.

The mesh pattern of the wiring portion 5 may include a plurality of first linear portions arranged parallel to each other and a plurality of second linear portions arranged parallel to each other. The angle between the first linear portions and the second linear portions, i.e., the smaller of two pairs of interior angles in the parallelogram or rhombus opening 5a formed by the mesh pattern, may be, for example, 10 to 90 degrees, or 10 to 45 degrees.

The conductor portion 2 may have a ground electrode 9 having a mesh-like pattern including a plurality of linear portions. The ground electrode 9 is provided between the two ground terminals 3 while surrounding the radiating element of the wiring portion 5. The width and shape of the linear portions constituting the ground electrode 9 may be the same as the width and shape of the linear portions constituting the wiring portion 5.

The conductor portion 2 may contain a metal. The conductor portion 2 may contain at least one metal selected from copper, nickel, cobalt, palladium, silver, gold, platinum, and tin, or may contain copper. The conductor portion 2 may be a metal plating formed by a plating method. The conductor portion 2 may further contain a non-metallic element such as phosphorus to the extent that appropriate conductivity is maintained.

The substrate 1 may be a laminate having a support film 11 and an underlayer 12 provided on the support film 11. The underlayer 12 is a layer provided for forming the conductor portion 2 by electroless plating or the like. When the conductor portion 2 is formed by another method, the underlayer 12 does not necessarily have to be provided.

The support film 11 may be a transparent film. The total light transmittance of the support film 11 may be 90 to 100%. The haze of the support film 11 may be 0 to 5%.

The transparent film may be a transparent resin film, examples of which include polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), cycloolefin polymer (COP), or polyimide (PI) films. Alternatively, the support film 11 may be a glass substrate.

The thickness of the support film 11 may be 10 μm or more, 20 μm or more, or 35 μm or more, and may be 500 μm or less, 200 μm or less, or 100 μm or less.

The undercoat layer 12 contains a catalyst and a resin. The resin may be a cured product of a curable resin composition. Examples of the curable resin contained in the curable resin composition include amino resins, cyanate resins, isocyanate resins, polyimide resins, epoxy resins, oxetane resins, polyesters, allyl resins, phenolic resins, benzoxazine resins, xylene resins, ketone resins, furan resins, COPNA resins, silicon resins, dicyclopentadiene resins, benzocyclobutene resins, episulfide resins, ene-thiol resins, polyazomethine resins, polyvinylbenzyl ether compounds, acenaphthylene, and ultraviolet-curable resins containing functional groups that undergo a polymerization reaction under ultraviolet light, such as unsaturated double bonds, cyclic ethers, and vinyl ethers.

The catalyst contained in the underlayer 12 may be an electroless plating catalyst. The electroless plating catalyst may be a metal selected from Pd, Cu, Ni, Co, Au, Ag, Pd, Rh, Pt, In, and Sn, or may be Pd. The catalyst may be one type alone or a combination of two or more types. Typically, the catalyst is dispersed in the resin as catalyst particles.

The catalyst content in the base layer 12 may be 3 mass% or more, 4 mass% or more, or 5 mass% or more, and may be 50 mass% or less, 40 mass% or less, or 25 mass% or less, based on the total amount of the base layer 12.

The thickness of the underlayer 12 may be 10 nm or more, 20 nm or more, or 30 nm or more, and may be 500 nm or less, 300 nm or less, or 150 nm or less.

The resin parts 7A and 7B can be formed from the same or different resins, and are provided so as to fill the opening 3a of the terminal part 6 (ground terminal 3) and the opening 5a of the wiring part 5, respectively. The conductor part 2 (wiring part 5 and terminal part 6) and the resin parts 7A and 7B may form a flat surface. In other words, the thickness of the conductor part 2 and the thickness of the resin parts 7A and 7B may be substantially the same. The thickness of the conductor part 2 and the resin parts 7A and 7B may be 0.5 μm or more, 1 μm or more, or 2 μm or more, and may be 10 μm or less, 5 μm or less, or 2 μm or less.

The resin parts 7A and 7B may be transparent resin layers. The resin parts 7A and 7B may be a cured product of a photocurable resin composition or a thermosetting resin composition. The photocurable resin composition or the thermosetting resin composition forming the resin parts 7A and 7B includes a curable resin, examples of which include acrylic resin, amino resin, cyanate resin, isocyanate resin, polyimide resin, epoxy resin, oxetane resin, polyester, allyl resin, phenol resin, benzoxazine resin, xylene resin, ketone resin, furan resin, COPNA resin, silicon resin, dicyclopentadiene resin, benzocyclobutene resin, episulfide resin, ene-thiol resin, polyazomethine resin, polyvinylbenzyl ether compound, acenaphthylene, and ultraviolet curable resins containing functional groups that undergo a polymerization reaction with ultraviolet light, such as unsaturated double bonds, cyclic ethers, and vinyl ethers.

The refractive index (nd25) of the resin parts 7A and 7B may be, for example, 1.0 or more, 1.7 or less, 1.6 or less, or 1.5 or less. The refractive index can be measured by a reflectance spectroscopic film thickness meter. The total light transmittance of the resin parts 7A and 7B may be 90 to 100%. The haze of the resin parts 7A and 7B may be 0 to 5%.

Figures 3 and 4 are process diagrams that diagrammatically show one embodiment of a method for manufacturing the conductive film 20 shown in Figures 1 and 2.

The method illustrated in Figures 3 and 4 includes forming a catalyst-containing base layer 12 on one main surface of a support film 11, as shown in (a) of Figure 3, forming a resin layer 7 including resin portions 7A and 7B on the surface of the base layer 12 opposite the support film 11, as shown in (b) of Figure 3, forming trenches 30a and 30b exposing the base layer 12 by an imprinting method using a mold 15 having protrusions 15a and 15b, as shown in (c) and (d) of Figure 4, and forming conductor portions 2 (ground terminal 3 and wiring portion 5) filling the trenches 30a and 30b by an electroless plating method in which a metal plating is grown from the base layer 12.

In the imprinting process, the mold 15 is pushed into the resin layer 7 (resin parts 7A and 7B) by moving it in the thickness direction of the resin layer 7 (resin parts 7A and 7B). The mold 15 may be pushed in until the tips of the convex parts 15a and 15b reach the underlayer 12. In that state, if the resin layer 7 (resin parts 7A and 7B) is a layer containing an uncured photocurable or thermosetting resin composition, it is cured. If the resin layer 7 is a layer containing a photocurable resin composition, the resin layer 7 is cured by irradiating it with light such as ultraviolet light. Thereafter, the mold 15 is removed to form trenches 30a and 30b having a shape that is an inversion of the shape of the convex parts 15a and 15b of the mold 15 ((d) of FIG. 4). The method for forming the trenches 30a and 30b is not limited to the imprinting method, and the trenches may be formed by, for example, laser, dry etching, or photolithography. The protrusion 15a and the trench 30a formed thereby have a width corresponding to the width W3 of the linear portion constituting the ground terminal 3. The protrusion 15b and the trench 30b formed thereby have a width corresponding to the width W5 of the linear portion constituting the wiring portion 5. As described above, when the width W3 is small, the trench for forming the ground terminal 3 can be formed efficiently and with high precision while suppressing the generation of resin residue in the trench portion. After removing the mold 15, the resin remaining on the base layer 12 in the trenches 30a, 30b may be removed by etching such as dry etching.

The mold 15 may be made of quartz, Ni, ultraviolet-curable liquid silicone rubber (PDMS), etc. The shape of the convex portions 15a and 15b of the mold 15 is designed according to the shape of the trench to be formed.

After the trenches 30a and 30b are formed, the conductor 2 (ground terminal 3 and wiring portion 5) filling the trenches 30a and 30b can be formed by an electroless plating method in which metal plating is grown from the underlayer 12. For example, a laminate consisting of the substrate 1 and the resin portions 7A and 7B on the substrate 1 can be immersed in an electroless plating solution containing metal ions to form metal plating as the conductor 2 starting from the catalyst contained in the underlayer 12. By forming the conductor 2, the conductive film 20 shown in FIG. 1 and FIG. 2 can be obtained. The entire conductor 2 may be formed at once by using a mold that further has a convex portion having a shape corresponding to the portion of the conductor 2 other than the ground terminal 3 and the wiring portion 5 (for example, the power supply terminal 8).

The electroless plating solution contains ions of the metals that make up the conductive pattern layer. The electroless plating solution may further contain phosphorus, boron, iron, etc.

The temperature of the electroless plating solution during the formation of the conductor portion 2 may be, for example, 40 to 90°C. The immersion time in the electroless plating solution varies depending on the thickness of the conductor portion 2, etc., but is, for example, 10 to 30 minutes.

The conductive film described above can be incorporated into an electronic device, for example as a planar transparent antenna. The electronic device can be, for example, a display device such as a liquid crystal display device or an organic electroluminescence display device.

DESCRIPTION OF THE REFERENCE NUMERALS 1...substrate, 1S...main surface of substrate, 2...conductor portion (wiring portion 5, terminal portion 6), 3...ground terminal, 5...wiring portion, 6...terminal portion (ground terminal 3, power supply terminal 8), 7...resin layer (resin portions 7A, 7B), 7A, 7B...resin portions, 8...power supply terminal, 11...support film, 12...underlayer, 15...mold, 20...conductive film, W3, W5...width of linear portion, W8...minimum width of power supply terminal.

Claims (8)

The device includes a film-like base material, a conductor portion extending on a main surface of the base material, a power supply terminal provided separately from the conductor portion, and a resin portion,
The conductor portion includes a wiring portion having a mesh-like pattern including a plurality of linear portions, and a terminal portion,
the terminal portion has a portion having a pattern including a plurality of openings,
the terminal portion has a terminal pattern portion that has a pattern including the plurality of openings and is an extending portion toward the outside of the wiring portion,
the power supply terminal is a conductor layer extending in a plane so as to cover a part of the terminal pattern portion and having a solid form without including an opening,
The resin portion fills the openings in the terminal portion.
Conductive film. The terminal portion has a ground terminal which is a portion having a pattern including the plurality of openings.
The conductive film according to claim 1 . The conductive film according to claim 1 or 2, wherein the wiring portion includes a radiating element of an antenna. The conductive film according to any one of claims 1 to 3, further comprising a resin portion filling the opening of the wiring portion. The conductive film according to any one of claims 1 to 4, wherein the pattern including the multiple openings in the terminal portion is a mesh-like pattern including multiple linear portions. The conductive film according to claim 5, wherein the width of the linear portion in the terminal portion is greater than the width of the linear portion in the wiring portion. The conductive film according to claim 5 or 6, wherein the width of the linear portion in the terminal portion is 200 μm or less. An electronic device comprising the conductive film according to any one of claims 1 to 7.

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