Conductive film

Abstract

A multilayer wiring board 1 includes: a sheet-like first insulator 5 having a plurality of projections 5b on the upper surface; a first groove 7 formed on the upper surface of the first insulator 5; a first thin metal wire 13 placed in the first groove 7 along the first groove 7; and a sheet-like second insulator 6 laminated directly on the first insulator 5. The plurality of projections 5b contain SiO2, project upward, and extend into the second insulator 6.

Description

Conductive film

[0001] The present disclosure relates to conductive films.

[0002] Patent Document 1 discloses a thin line structure provided on a substrate and a touch sensor including the thin line structure, in which at least one bottomed groove is provided on at least one outer surface of the substrate, and a conductive layer made of a conductive material is provided in the groove.

[0003] Patent Document 1 also discloses a fine wire structure in which a first resin layer is formed on the outer surface of a substrate and in a plurality of groove portions, and a second resin layer is further formed on the outer surface of the substrate positioned around each groove portion (see paragraphs 0048 to 0050, 0059 to 0060 and FIG. 7 in the specification of Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2023-179898

[0005] In the configuration in which a second resin layer is laminated on a first resin layer, as shown in FIG. 7 of Patent Document 1, there is a demand for increasing the adhesive strength between the two layers.

[0006] The present disclosure has been made in consideration of these points, and its purpose is to increase the adhesive strength between a sheet-like first insulator on which a first metal thin wire is arranged and a sheet-like second insulator laminated on the first insulator.

[0007] One embodiment of the present disclosure relates to a conductive film, the conductive film including: a first insulator sheet having a plurality of protrusions on an upper surface thereof; a first groove formed on the upper surface of the first insulator; a first thin metal wire arranged along the first groove; and a second insulator sheet laminated directly on the first insulator, the plurality of protrusions being made of SiO ２ the plurality of protrusions protrude upward, and the plurality of protrusions penetrate into the second insulator.

[0008] According to the present disclosure, it is possible to increase the adhesive strength between a sheet-like first insulator on which a first thin metal wire is arranged and a sheet-like second insulator laminated on the first insulator.

[0009] FIG. 1 is a perspective view showing a multilayer wiring board according to an embodiment of the present disclosure. FIG. 2 is a plan view showing a multilayer wiring board according to an embodiment of the present disclosure. FIG. 3 is a partially enlarged plan view showing an enlarged view of section III in FIG. 2. FIG. 4 is a partially enlarged plan view showing an enlarged view of section IV in FIG. 3. FIG. 5 is a partially enlarged plan view showing an enlarged view of section V in FIG. 4. FIG. 6 is a partially enlarged plan view showing an enlarged view of section VI in FIG. 4. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 6. FIG. 9 is a partially enlarged cross-sectional view showing an enlarged view of section IX in FIGS. 7 and 8. FIG. 10 is a cross-sectional view showing first fine metal wires and second fine metal wires according to a modified embodiment. FIG. 11 is a cross-sectional view showing first groove portions and second groove portions according to a modified embodiment. FIG. 12 is a partially enlarged view showing a multilayer wiring board according to an example. ２ 13 is an SEM image showing a cross section near the upper surface of a resin molded body before plasma treatment. FIG. 14 is an SEM image showing a plan view of the upper surface of a resin molded body in an example. ２ 15 is an SEM image showing a cross section near the upper surface of the resin molded body after plasma treatment. Fig. 15 is an SEM image showing a plan view of the upper surface of the resin molded body in Fig. 14 .

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses. Note that the relative dimensions of the various components shown in the drawings are not necessarily the same as the actual relative dimensions.

[0011] 1 and 2 show the overall configuration of a multilayer wiring board 1 (conductive film) according to an embodiment of the present disclosure. In this embodiment, a multilayer wiring board 1 formed by an imprinting method is illustrated. The multilayer wiring board 1 is provided with a plurality of mounting elements 2. Examples of the mounting elements 2 include LED elements or diodes. The mounting elements 2 are arranged above a substrate 3 (described later) (toward the upper surface of a first insulator 5 (described later)).

[0012] In this embodiment, for convenience of explanation, the direction from the left to the right on the paper surface in FIG. 2 is defined as the "X direction," and the direction from the bottom to the top on the paper surface in FIG. 2 is defined as the "Y direction."

[0013] 1 and 2, the multilayer wiring board 1 includes a substrate 3. The substrate 3 is transparent and light-transmitting. In this embodiment, in the thickness direction of the substrate 3, the side on which a film base 4 (described later) is located is defined as the "lower side" of the substrate 3, and the side on which a second insulator 6 (described later) is located is defined as the "upper side" of the substrate 3.

[0014] The substrate 3 includes a film substrate 4. The film substrate 4 is made of a resin material that is at least flexible and light-transmitting. Preferably, the film substrate 4 has a light transmittance of 80% or more. The film substrate 4 is, for example, 25 μm to 200 μm. The film substrate 4 is also transparent. Examples of resin materials for the film substrate 4 include resin materials such as PET (polyethylene terephthalate), polycarbonate, COP (cycloolefin polymer), and COC (cycloolefin copolymer).

[0015] As shown in Figures 7 and 8, the substrate 3 includes a sheet-like first insulator 5 laminated on the film substrate 4 and a sheet-like second insulator 6 laminated on the first insulator 5. Each of the first insulator 5 and the second insulator 6 is made of a resin material having insulating properties and optical transparency. This resin material is, for example, a thermosetting resin or a UV-curable resin material. Specifically, the resin material of the first insulator is preferably a solventless UV-curable resin. The solventless UV-curable resin includes a base resin, a reactive diluent, a photopolymerization initiator, and other additives.

[0016] The base resin is preferably a (meth)acrylate, urethane (meth)acrylate, or epoxy (meth)acrylate monomer, oligomer, or a combination thereof. In particular, in this embodiment, it is preferable to use one or a combination of the silicone-modified monomers and oligomers, and among them, the silicone-modified monomers or oligomers alone or a combination thereof is more preferable. The silicone-modified monomers and oligomers are, for example, polymers into which a silane coupling agent has been chemically introduced, and are prepared by reacting the silane coupling agent with the end or side chain of the polymer, or by copolymerizing the silane coupling agent with the monomer, or by other methods.

[0017] The photopolymerization initiator is not particularly limited as long as it generates radicals, ions, etc. when irradiated with ultraviolet light and initiates a polymerization reaction of monomers or oligomers, and photopolymerization initiators that generate radicals when irradiated with ultraviolet light are particularly preferred.

[0018] Other additives include antioxidants, surfactants, release agents, fillers, leveling agents, etc. The reactive diluent can be appropriately selected from monofunctional, difunctional, trifunctional, tetrafunctional or higher polyfunctional (meth)acrylate monomers.

[0019] Specific examples of solvent-free UV curable resins include, but are not limited to, LUXYDIR (registered trademark) manufactured by DIC Corporation, ELFORT (registered trademark) manufactured by Resonac Corporation, ACTFLOW (registered trademark) manufactured by Soken Chemical & Engineering Co., Ltd., and SHIKOH (registered trademark) manufactured by Mitsubishi Chemical Corporation.

[0020] The thickness of each of the first insulator 5 and the second insulator 6 is, for example, 1 μm to 6 μm. An adhesive portion 5 a (described later) is provided between the first insulator 5 and the second insulator 6, bonding the first insulator 5 and the second insulator 6 to each other.

[0021] The first insulator 5 contains Si atoms because its upper surface reacts with a silane coupling agent during the manufacturing process, as described below. On the other hand, the second insulator 6 may or may not contain Si atoms. When the second insulator 6 contains Si atoms, the Si content of the first insulator 5 is higher than the Si content of the second insulator 6.

[0022] A first groove 7 is formed on the upper surface of the first insulator 5, and a first thin metal wire 13 is arranged along the extension direction of the first groove 7. The groove depth of the first groove 7 is set to be, for example, not less than 0.5 μm and not more than 5 μm. The first thin metal wire 13 constitutes a first conductor pattern 10, which will be described later.

[0023] The second insulator 6 has a second groove 8 formed on its upper surface, and a second thin metal wire 17 arranged along the extension direction of the second groove 8. The depth of the second groove 8 is set to, for example, 0.5 μm or more and 5 μm or less. The second thin metal wire 17 constitutes a second conductor pattern 14, which will be described later.

[0024] As shown in FIG. 7, the bottom of the second groove 8 penetrates the second insulator 6 in the thickness direction in a portion where a via portion 22 (described later) is formed.

[0025] As shown in Fig. 9, the first insulator 5 has a plurality of protrusions 5b located on the upper surface of the first insulator 5. The plurality of protrusions 5b protrude upward in a pin-holder or needle shape. The resin material constituting the second insulator 6 is filled between adjacent protrusions 5b. That is, the surface of the protrusions 5b is in contact with the second insulator 6. In other words, the protrusions 5b penetrate into the second insulator 6. Note that the shape of the plurality of protrusions 5b is not limited to a pin-holder or needle shape as long as they protrude upward.

[0026] - Adhesive portion - The first insulator 5 has an adhesive portion 5a on its upper surface. The adhesive portion 5a has a plurality of protruding portions 5b and a flat portion 5c. The first insulator 5 and the second insulator 6 are bonded to each other by the chemical or physical bond of the protruding portions 5b. The anchor effect of the plurality of protruding portions 5b provides a large adhesive strength at the adhesive portion 5a.

[0027] The first insulator 5 has a flat portion 5c where the polymer constituting the resin material of the first insulator 5 is bonded to the polymer constituting the resin material of the second insulator 6 via an atomic group containing at least Si atoms or via Si atoms. The flat portion 5c may be distributed over the entire surface of the adhesive portion 5a or may be distributed over a part of the surface of the adhesive portion 5a. The "atomic group containing at least Si atoms" may be, for example, SiO ２ That is, in the adhesive portion 5a, at least a part of the resin material constituting the first insulator 5 has SiO as a molecular skeleton. ２ The first insulator 5 and the second insulator 6 are made of a modified polymer containing SiO ２ The SiO 2 particles are bonded to each other by covalent bonds. ２ The O is a product of the treatment with a silane coupling agent during the manufacturing process described below. ２ It can be introduced by plasma treatment. ２ As a result of these treatments, SiO is distributed more on the tip end side of the protrusion 5b than on the base end side. ２ The distribution of covalent bonds via a silyl group is low, while the distribution of other bond modes is high. The "other bond" refers to, for example, a chemical bond or physical bond such as a covalent bond between the polymer of the first insulator 5 and the polymer of the second insulator 6, either directly or via a silyl group.

[0028] 1 to 3, the multilayer wiring substrate 1 includes a plurality of first conductor patterns 10 formed from first thin metal wires 13. The plurality of first conductor patterns 10 are arranged at intervals (equally spaced in the illustrated example) from one another in the X direction in a plan view. Note that, for convenience of illustration, in FIGS. 1 to 3, each first conductor pattern 10 is simply illustrated by dot hatching.

[0029] Each first conductor pattern 10 has a first main body 11 and a plurality of (four in the illustrated example) first branch portions 12. The first main body 11 and each first branch portion 12 are formed in a generally strip-like shape in a plan view. The first main body 11 extends in a generally strip-like shape along the Y direction in a plan view. Each first branch portion 12 branches off from a midpoint of the first main body 11. Specifically, each first branch portion 12 is configured to extend from a midpoint of the first main body 11 in a direction opposite to the X direction (toward the left side of the paper in FIGS. 2 and 3 ).

[0030] Each of the first thin metal wires 13 constituting the first conductor pattern 10 is configured to have a line width of, for example, 15 μm or less. In this embodiment, the first grooves 7 and the first thin metal wires 13 have a substantially rectangular shape in a cross section ( FIGS. 7 and 8 ) cut perpendicular to the direction in which the first grooves 7 extend. The multiple first thin metal wires 13 are arranged in a predetermined pattern on the top surface of the first insulator 5. FIG. 4 shows a mesh pattern in which the multiple first thin metal wires 13 are arranged in a mesh shape as an example of the predetermined pattern.

[0031] The mesh pattern (first conductor pattern 10) made up of a plurality of first thin metal wires 13 is configured so that the plurality of first thin metal wires 13 intersect with one another and are arranged at predetermined intervals (equal intervals in the illustrated example). Each of the first thin metal wires 13 making up the mesh pattern extends in an oblique direction with respect to both the X direction and the Y direction.

[0032] 1 to 3, the multilayer wiring board 1 includes a plurality of second conductor patterns 14. The plurality of second conductor patterns 14 are arranged at intervals (equally spaced apart in the illustrated example) in the Y direction in a plan view. Note that, for convenience of illustration, the second conductor patterns 14 are simply illustrated by dot hatching in FIGS. 1 to 3.

[0033] Each second conductor pattern 14 has a second main body portion 15 and a plurality of (four in the illustrated example) second branch portions 16. The second main body portion 15 and each second branch portion 16 are formed in a generally strip-like shape in a plan view. The second main body portion 15 extends in a generally strip-like shape along the X direction in a plan view. Each second branch portion 16 branches off from a midpoint of the second main body portion 15. Specifically, each second branch portion 16 extends from a midpoint of the second main body portion 15 in a direction opposite to the Y direction (downward in the plane of FIG. 2 ).

[0034] Each of the second thin metal wires 17 constituting the second conductor pattern 14 is configured to have a line width of, for example, 15 μm or less. In this embodiment, the second grooves 8 and the second thin metal wires 17 have a substantially rectangular shape in a cross section cut perpendicular to the extension direction of the second grooves 8. As shown in FIGS. 4 and 5 , the multiple second thin metal wires 17 are arranged in a predetermined pattern on the upper surface of the second insulator 6. FIG. 4 shows a mesh pattern in which the multiple second thin metal wires 17 are arranged in a mesh shape as an example of the predetermined pattern. Note that in FIG. 4 , in order to distinguish between the first thin metal wires 13 and the second thin metal wires 17, the second thin metal wires 17 are illustrated using thicker lines than the first thin metal wires 13.

[0035] The mesh pattern (second conductor pattern 14) made up of the plurality of second thin metal wires 17 is configured so that the plurality of second thin metal wires 17 intersect with each other and are arranged at predetermined intervals (equal intervals in the illustrated example). Each of the second thin metal wires 17 making up the mesh pattern extends in an oblique direction with respect to both the X direction and the Y direction.

[0036] 3 and 4 , an overlapping pattern 20 is provided on the first conductor pattern 10 and the second conductor pattern 14. The overlapping pattern 20 is configured so that a portion of the first conductor pattern 10 and a portion of the second conductor pattern 14 overlap in the thickness direction of the substrate 3. The overlapping pattern 20 of this embodiment is configured so that a portion of the first branch portion 12 and a portion of the second branch portion 16 overlap in the thickness direction of the substrate 3.

[0037] In the overlapping pattern 20, the spacing between the first thin metal wires 13 is larger than the spacing between the first thin metal wires 13 in the first conductor pattern 10 other than the overlapping pattern 20. In this embodiment, the spacing between the first thin metal wires 13 in the overlapping pattern 20 is about twice the spacing between the first thin metal wires 13 in the first conductor pattern 10 other than the overlapping pattern 20. Similarly, the spacing between the second thin metal wires 17 in the overlapping pattern 20 is about twice the spacing between the second thin metal wires 17 in the second conductor pattern 14 other than the overlapping pattern 20.

[0038] In overlapping pattern 20, a plurality of first thin metal wires 13 and a plurality of second thin metal wires 17 intersect with each other in a planar view. Overlapping pattern 20 is configured such that, in a planar view, each of first thin metal wires 13 and each of second thin metal wires 17 is arranged at a predetermined interval (equal intervals in the illustrated example).

[0039] 4 and 5, the overlapping pattern 20 includes a connection region 21. In the connection region 21, the first thin metal wires 13 and the second thin metal wires 17 are electrically connected. Note that the overlapping pattern 20 of this embodiment includes one connection region 21. In the connection region 21, multiple first thin metal wires 13 intersect with one second thin metal wire 17 (see intersection points P shown in FIG. 5). Four intersection points P are located in the connection region 21 shown in FIG. 5.

[0040] 7, each second thin metal wire 17 located in the connection region 21 is provided with one via portion 22. The via portion 22 is arranged in the connection region 21. The via portion 22 is made of the same material as each second thin metal wire 17 (the conductive layer 172 described below).

[0041] The via portion 22 is formed integrally with the second thin metal wire 17 located in the connection region 21. The via portion 22 in this embodiment protrudes from the lower portion of the second thin metal wire 17 toward a position corresponding to the upper surface of the first insulator 5. The via portion 22 is configured so that its line width is equal to or smaller than the line width of the second thin metal wire 17.

[0042] At the intersections (intersections P shown in FIG. 5 ) where the first thin metal wires 13 and the second thin metal wires 17 intersect in the connection region 21, the via portions 22 are configured to be electrically connected to the first thin metal wires 13. In this embodiment, at the intersections P, the lower surfaces of the via portions 22 contact the upper surfaces of the first thin metal wires 13 located in the connection region 21.

[0043] In this embodiment, the via portion 22 is electrically connected to the two first thin metal wires 13 at two intersections P, P where the two first thin metal wires 13 intersect with one second thin metal wire 17. In this embodiment, one via portion 22 overlaps in the thickness direction of the substrate 3 with two first thin metal wires 13 that are adjacent to each other in the extension direction of the second thin metal wire 17 (see FIG. 7 ).

[0044] 3 and 4, the multilayer wiring substrate 1 includes a plurality of dummy patterns 30. In Fig. 3, each dummy pattern 30 is simply indicated by dot hatching. Note that in Figs. 1 and 2, each dummy pattern 30 is omitted from illustration.

[0045] In this embodiment, the multiple dummy patterns 30 are arranged on the first insulator 5. Specifically, the multiple dummy patterns 30 are arranged in a region of the first insulator 5 where the first conductor pattern 10 and the second conductor pattern 14 are not located in a plan view (see FIGS. 1 and 2 ).

[0046] 4, the dummy pattern 30 is composed of a plurality of dummy conductive lines 31. Each dummy conductive line 31 is thinned. Specifically, the line width of each dummy conductive line 31 is set to 15 μm or less.

[0047] A third groove (not shown) is provided on the upper surface of the first insulator 5, and each dummy conductive line 31 is arranged along the direction in which this third groove extends. Each dummy conductive line 31 is made of a conductive metal selected from, for example, copper, silver, gold, or an alloy containing at least one of these metals. The third groove is formed in a region of the first insulator 5 where the first conductor pattern 10 is not located in plan view. Otherwise, the configuration of the third groove is the same as that of the first groove 7. The upper surface of each dummy conductive line 31 may be formed to be flush with the upper surface of the first insulator 5.

[0048] The plurality of dummy conductive wires 31 are configured in a mesh pattern in which the plurality of dummy conductive wires 31 are arranged in a mesh shape. The mesh pattern configured in the plurality of dummy conductive wires 31 has the same configuration as the mesh pattern configured in the plurality of first thin metal wires 13.

[0049] In plan view, the multiple dummy conductive wires 31 are arranged at intervals from the multiple first thin metal wires 13 that constitute the first conductor pattern 10 adjacent to each dummy pattern 30. In other words, each dummy pattern 30 is not electrically connected to the first conductor pattern 10. Furthermore, although not shown, each dummy pattern 30 is insulated from each second conductor pattern 14 via a second insulator 6.

[0050] -Method of Forming Protrusions- A method of forming the plurality of protrusions 5b in the first insulator 5 will be described below. This method is carried out during the manufacturing process of the multilayer wiring substrate 1.

[0051] In the first step, a resin molded body that will become the first insulator 5 and that has the first thin metal wires 13 provided thereon is prepared, and a silane coupling agent is reacted with the upper surface of this resin molded body at the portion that contacts the second insulator 6. As a result, silyl groups are introduced into the main chain and side chain of the polymer that constitutes the resin molded body at the portion that contacts the second insulator 6. Examples of silane coupling agents include A-1110, A-1120, A-2120, and A-1871 manufactured by Momentive Corporation; DOWSIL (registered trademark) Z-6011 Silane, DOWSIL Z-6020 Silane, DOWSIL Z-6094 Silane, and DOWSIL Z-6062 Silane manufactured by Dow-Toray Industries, Inc.; and X-40-2761, X-48-5030, and X-48-5031 manufactured by Shin-Etsu Silicones Co., Ltd.

[0052] Next, in the second step, O ２ Oxidation is achieved by plasma treatment. ２ The time for plasma treatment is preferably 4 minutes or more, and more preferably 4.5 to 5.5 minutes, for example, in the case of an RIE plasma method using an RF frequency, in which an apparatus having a high frequency output of 100 W and an electrode of 200 mm diameter is used. ２ By the plasma treatment, the upper surface of the resin molded body is transformed into glassy SiO2 at the site where the silyl groups introduced in the first step are present. ２ and the other parts (mainly parts consisting of carbon atoms and hydrogen atoms) are oxidized to CO ２ As a result, SiO ２ The portion including O remains on the resin molding (first insulator 5 in FIG. 9) as a protrusion 5b as shown in FIG. ２ After the plasma treatment, ２ Compared to before the plasma treatment, the ratios (molar ratios) of Si and O among the main atoms (for example, C, N, O, Si, P, and S) constituting the upper surface of the resin molded body are increased by 2.5 to 3 times. ２ It contains O ２Since this is the portion that remains without being vaporized after the plasma treatment, the ratio of Si among the atoms that make up the protrusion 5b is higher than the ratio of Si in other portions.

[0053] In this manner, the first insulator 5 having the protrusions 5b formed thereon is obtained. Then, a resin material for forming the second insulator 6 is poured onto the upper surface of the first insulator 5 and cured. As a result, the resin material for the second insulator 6 also fills the spaces between adjacent protrusions 5b, and a laminate of the first insulator 5 and the second insulator 6 is obtained as shown in FIG.

[0054] - Function and Effect - The solventless UV-curable resin constituting the first insulator 5 and the second insulator 6 does not contain an organic solvent, but instead contains a reactive diluent. The reactive diluent contains a low-molecular-weight monomer involved in a polymerization reaction, and this low-molecular-weight monomer substitutes for the organic solvent in providing functions such as solubility, wettability, and permeability. However, the low-molecular-weight monomer has a larger molecular weight and lower permeability than the organic solvent. Therefore, when an uncured solventless UV-curable resin is applied to the cured first insulator 5 and the second insulator 6 is laminated thereon, the uncured solventless UV-curable resin has low permeability into the first insulator 5, and sufficient adhesion between the first insulator 5 and the second insulator 6 may not be achieved. For these reasons, when the first insulator 5 and the second insulator 6 are made of a solventless UV-curable resin, adhesion between the layers is poor, and there is a significant demand for increased adhesive strength between the two layers.

[0055] In this embodiment, the adhesive portion 5a of the first insulator 5 to the second insulator 6 is made of SiO ２ Therefore, the first insulator 5 and the second insulator 6 contain SiO ２ The first insulator 5 and the second insulator 6 are bonded to each other by chemical and physical bonds involving the protrusions 5b. Furthermore, because the first insulator 5 has a plurality of protrusions 5b, the anchor effect of the protrusions 5b further increases the adhesive strength between the first insulator 5 and the second insulator 6 compared to when the protrusions 5b are not provided. From the above, even when the first insulator 5 and the second insulator 6 are made of a solventless UV-curable resin, the adhesive strength between the first insulator 5 and the second insulator 6 can be increased.

[0056] Furthermore, the first insulator 5 and the second insulator 6 have SiO in the main chain or side chain of the polymer in the adhesive portion 5a. ２ The adhesion is also achieved by chemical bonds involving sites other than the above (for example, silyl groups), and the adhesive strength is significantly greater than in the absence of such chemical bonds.

[0057] In this embodiment, the first insulator 5 contains Si atoms, and the Si content of the first insulator 5 is greater than the Si content of the second insulator 6. The first insulator 5 is made of a resin material containing a polymer having a silyl group. This structure can be obtained by reacting a silane coupling agent on the upper surface of the resin molded body that will become the first insulator 5. That is, as described above, SiO ２ It is possible to manufacture a laminate of the first insulator 5 and the second insulator 6 having strong adhesive strength due to chemical and physical bonds involving the above.

[0058] The multilayer wiring substrate 1 according to this embodiment can be widely applied to various technical fields such as touch sensors, liquid crystal display devices, organic electroluminescence display devices (OLEDs), micro LED display devices, solar cell devices, heater devices, antenna devices, and electromagnetic wave shielding sheets.

[0059] (Modification of the embodiment) Instead of the above embodiment, the first groove portion 7 and the second groove portion 8, and the first thin metal wires 13 and the second thin metal wires 17 arranged therein may be configured as follows: In the following description, the same reference numerals as those in the above embodiment are used to designate components common to the above embodiment.

[0060] 10 and 11 , the first thin metal wire 13 includes a conductive material embedded in a first groove 7 formed in the first insulator 5. The first groove 7 is composed of a bottom surface 7a (first bottom surface) extending in the width direction (left-right direction in the drawing), a side surface 7b (first side surface) connecting the bottom surface 7a to the opening of the first groove 7, and a corner portion 7c connecting the bottom surface 7a and the side surface 7b. The bottom surface 7a is located below the first thin metal wire 13. The side surface 7b is located to the side of the first thin metal wire 13.

[0061] The first thin metal wire 13 includes an adhesive layer 131 (first adhesive layer) and a conductive layer 132 (first conductive layer). The adhesive layer 131 covers the inner surface of the first groove portion 7. The conductive layer 132 is disposed on the adhesive layer 131 along the adhesive layer 131.

[0062] The adhesion layer 131 is an element for ensuring adhesion of the conductive layer 132 to the first groove portion 7. The adhesion layer 131 also has low reflectivity. That is, the adhesion layer 131 has the function of making the conductive layer 132 less visible when the multilayer wiring substrate 1 is viewed from the side where the first insulator 5 is located (from the bottom of the paper in FIG. 10 ).

[0063] The adhesion layer 131 is a metal layer composed of, for example, a metal nitride containing at least one metal selected from the group consisting of Ti, Al, V, W, Ta, Si, Cr, Ag, Mo, Cu, Zn, and Ni, a metal oxide, or a metal oxynitride containing both a metal nitride and a metal oxide. The adhesion layer 131 may be a single layer or a laminate of multiple layers with different compositions. The adhesion layer 131 is disposed on the first groove portion 7 as a thin film by, for example, vapor deposition or sputtering.

[0064] The adhesive layer 131 includes a bottom surface portion 131a formed on the bottom surface 7a of the first groove portion 7 and a side surface portion 131b formed on the side surface 7b of the first groove portion 7. The bottom surface portion 131a and the side surface portion 131b are connected via a connecting portion 131c formed along a corner portion 7c of the first groove portion 7. The first groove portion 7 has a curved fillet formed at the corner portion 7c. Specifically, the corner portion 7c is formed so that the curvature gradually changes from the bottom surface 7a to the side surface 7b. That is, the bottom surface 7a and the side surface 7b are connected at the corner portion 7c so that the angle continuously changes. Therefore, the bottom surface 7a and the side surface 7b are smoothly connected by the corner portion 7c. Furthermore, because the connecting portion 131c is formed along the corner portion 7c of the first groove portion 7, the bottom surface portion 131a and the side surface portion 131b are smoothly connected by the connecting portion 131c. The corner portion 7c may be formed so that the curvature is constant.

[0065] The conductive layer 132 is an element that ensures the conductivity of the first metal thin wires 13. The conductive layer 132 is embedded in the first groove portion 7 while being stacked on the adhesion layer 131. The conductive layer 132 is made of a conductive metal. Suitable conductive metals include, for example, copper, silver, gold, and alloys containing at least one of these metals. The conductive layer 132 is formed by, for example, vapor deposition, sputtering, electroless plating, or electroplating. Preferably, the upper surface of the conductive layer 132 is formed flush with the upper surface of the first insulator 5.

[0066] A blackening layer 133 is formed on the upper surface of the conductive layer 132. The blackening layer 133 has low reflectivity. That is, the blackening layer 133 has the function of making the conductive layer 132 less visible when the multilayer wiring substrate 1 is viewed from the side where the second insulator 6 is located. The blackening layer 133 is formed by, for example, vapor deposition, sputtering, electrolytic plating, or electroless plating.

[0067] When the blackening layer 133 is formed by, for example, the above-described electroless plating process, the composition of the electroless plating solution used in the electroless plating process is not particularly limited. For example, when the metal atoms of the conductive layer 132 are copper, the atoms substituted for copper (i.e., the constituent atoms of the blackening layer 133) may be one element selected from the group consisting of Pd, Hg, Ag, Ir, Pt, and Au. In the following description, the case where palladium (Pd) is used as the constituent atom of the blackening layer 133 is exemplified.

[0068] The blackened layer 133 is formed by substituting, with palladium (blackening treatment), crystal grains located at the boundaries between crystal grains (so-called "grain boundaries") on the surface side of the conductive metal that constitutes the conductive layer 132. Specifically, in the blackening treatment, intergranular corrosion progresses along the grain boundaries, and crystal grains such as copper that constitute the surface layer of the conductive metal are substituted with palladium.

[0069] 10 and 11 , the second thin metal wire 17 includes a conductive material embedded in a second groove 8 formed in the second insulator 6. The second groove 8 is composed of a bottom surface 8a (second bottom surface) extending in the width direction (left-right direction in the drawing), a side surface 8b (second side surface) connecting the bottom surface 8a to the opening of the second groove 8, and a corner portion 8c connecting the bottom surface 8a and the side surface 8b. The bottom surface 8a is located below the second thin metal wire 17. The side surface 8b is located to the side of the second thin metal wire 17.

[0070] The second thin metal wire 17 includes an adhesive layer 171 and a conductive layer 172 (second conductive layer). The adhesive layer 171 covers the inner surface of the second groove portion 8. The conductive layer 172 is disposed on the adhesive layer 171 along the adhesive layer 171.

[0071] The adhesion layer 171 is an element for ensuring adhesion of the conductive layer 172 to the second groove portion 8. The adhesion layer 171 also has low reflectivity. That is, the adhesion layer 171 has the function of making the conductive layer 172 less visible when the multilayer wiring substrate 1 is viewed from the side where the first insulator 5 is located (from the bottom of the paper in FIG. 10 ).

[0072] The adhesion layer 171 is a metal layer composed of, for example, a metal nitride containing at least one metal selected from the group consisting of Ti, Al, V, W, Ta, Si, Cr, Ag, Mo, Cu, Zn, and Ni, a metal oxide, or a metal oxynitride containing both a metal nitride and a metal oxide. The adhesion layer 171 may be a single layer or a laminate of multiple layers with different compositions. The adhesion layer 171 is disposed in the form of a thin film on the second groove portion 8 by, for example, vapor deposition or sputtering.

[0073] The adhesive layer 171 includes a bottom surface portion 171a formed on the bottom surface 8a of the second groove portion 8 and a side surface portion 171b formed on the side surface 8b of the second groove portion 8. The bottom surface portion 171a and the side surface portion 171b are connected via a connecting portion 171c formed along a corner portion 8c of the second groove portion 8. The second groove portion 8 has a curved fillet formed at the corner portion 8c. Specifically, the corner portion 8c is formed so that the curvature gradually changes from the bottom surface 8a to the side surface 8b. That is, the bottom surface 8a and the side surface 8b are connected so that the angle continuously changes at the corner portion 8c. Therefore, the bottom surface 8a and the side surface 8b are smoothly connected by the corner portion 8c. Furthermore, since the connecting portion 171c is formed along the corner portion 8c of the second groove portion 8, the bottom surface portion 171a and the side surface portion 171b are smoothly connected by the connecting portion 171c.

[0074] The conductive layer 172 is an element that ensures the conductivity of the second thin metal wires 17. The conductive layer 172 is embedded in the second groove portion 8 while being stacked on the adhesion layer 171. The conductive layer 172 is made of a conductive metal. Suitable conductive metals include, for example, copper, silver, gold, and alloys containing at least one of these metals. The conductive layer 172 is formed by, for example, vapor deposition, sputtering, electroless plating, or electroplating. Preferably, the upper surface of the conductive layer 172 is formed flush with the upper surface of the second insulator 6.

[0075] A blackening layer 173 is laminated on the upper surface of the conductive layer 172. The blackening layer 173 has low reflectivity. That is, the blackening layer 173 has the function of making the conductive layer 172 less visible when the multilayer wiring substrate 1 is viewed from the side where the second insulator 6 is located. The blackening layer 173 is formed by, for example, vapor deposition, sputtering, electrolytic plating, or electroless plating.

[0076] When the blackening layer 173 is formed by, for example, the above-described electroless plating process, the composition of the electroless plating solution used in the electroless plating process is not particularly limited. For example, if the metal atoms of the conductive layer 172 are copper, the atoms substituted for the copper (i.e., the constituent atoms of the blackening layer 173) may be one element selected from the group consisting of Pd, Hg, Ag, Ir, Pt, and Au. In the following description, the case where palladium (Pd) is used as the constituent atom of the blackening layer 173 is exemplified.

[0077] The blackened layer 173 is formed by substituting, with palladium (blackening treatment), crystal grains located at the boundaries between crystal grains (so-called "grain boundaries") on the surface side of the conductive metal that constitutes the conductive layer 172. Specifically, in the blackening treatment, intergranular corrosion progresses along the grain boundaries, and crystal grains such as copper that constitute the surface layer of the conductive metal are substituted with palladium.

[0078] 11 , if the groove width of the first groove portion 7 in which the first thin metal wires 13 are embedded is defined as groove width W1 (first groove width) and the groove width of the second groove portion 8 in which the second thin metal wires 17 are embedded is defined as groove width W2 (second groove width), groove width W2 is wider than groove width W1. If the angle formed between the bottom surface 7 a and the side surface 7 b of the first groove portion 7 is defined as angle D1 (first angle) and the angle formed between the bottom surface 8 a and the side surface 8 b of the second groove portion 8 is defined as angle D2 (second angle), angle D2 is larger than angle D1.

[0079] This configuration makes it easier to make the cross-sectional area of ​​the second thin metal wires 17 larger than that of the first thin metal wires 13. This, together with the fact that the electrical resistance of a conductor is inversely proportional to the cross-sectional area of ​​the conductor, makes it easier to reduce the wiring resistance of the second thin metal wires 17.

[0080] As shown in Figure 10, if the thickness of the adhesion layer 131 on the first bottom surface 7a of the first metal thin wire 13 is thickness L11 and the thickness of the adhesion layer 171 on the second bottom surface 8a of the second metal thin wire 17 is thickness L21, thickness L21 is greater than thickness L11.

[0081] In this way, by increasing the thickness of the adhesive layer 171, the second thin metal wires 17 can be made less visible when the multilayer wiring substrate 1 is viewed from below.

[0082] The thickness of the adhesion layer 131 may be constant, or as shown in FIG. 10 , the thickness L11 on the bottom surface 7 a may be greater than the thickness L12 near the side surface 7 b. In this case, the thickness of the adhesion layer 131 near the corner 8 c is formed so that the thickness gradually changes from the bottom surface 8 a toward the side surface 8 b. As described above, the bottom surface 7 a and the side surface 7 b of the first groove portion 7 are connected at the corner 7 c so that the angle continuously changes. This configuration can suppress a sudden change in light reflection at the connection portion 131 c connecting the bottom surface portion 131 a and the side surface portion 131 b of the adhesion layer 131, making the first thin metal wire 13 less visible.

[0083] Similarly, the thickness of the adhesion layer 171 may be constant, or as shown in FIG. 10 , the thickness L21 on the bottom surface 8a may be greater than the thickness L22 near the side surface 8b. In this case, the thickness of the adhesion layer 171 near the corner 7c is formed so that the thickness gradually changes from the bottom surface 8a toward the side surface 8b. As described above, the bottom surface 8a and the side surface 8b of the second groove portion 8 are connected at the corner 8c so that the angle continuously changes. This configuration can suppress a sudden change in light reflection at the connection portion 171c connecting the bottom surface portion 171a and the side surface portion 171b of the adhesion layer 171, making the second thin metal wire 17 less visible.

[0084] If the thickness of the blackened layer 133 of the first thin metal wire 13 is thickness L13 and the thickness of the blackened layer 173 of the second thin metal wire 17 is thickness L23, thickness L13 is greater than thickness L23.

[0085] This makes the thickness L23 of the blackened layer 173 of the second thin metal wire 17 relatively small, which improves the connection stability when the second thin metal wire 17 is connected to an external wiring and reduces the rust prevention and visibility of the second thin metal wire 17. On the other hand, since the thickness L13 of the blackened layer 133 of the first thin metal wire 13 is relatively large, the first thin metal wire 13 and the second thin metal wire 17 are more likely to be electrically connected via the blackened layer 133, improving the connection stability between the first thin metal wire 13 and the second thin metal wire 17.

[0086] Other Embodiments The conductive film according to the present disclosure is not limited to the above-described embodiment, and various modifications are possible within the scope of the present disclosure. For example, the conductive film does not need to include the film substrate 4 and the second thin metal wires 17 (second conductive pattern 10). The first insulator 5 and the second insulator 6 of the substrate 3 do not need to be transparent.

[0087] In the above embodiment, each of the first conductor patterns 10 is formed of a mesh pattern in which a plurality of first thin metal wires 13 are arranged in a mesh shape, but this is not limiting. Similarly, each of the second conductor patterns 14 is not limited to a mesh pattern in which a plurality of second thin metal wires 17 are arranged in a mesh shape.

[0088] In the above embodiment, the dummy patterns 30 are disposed on the first insulator 5, but the present invention is not limited to this. That is, the dummy patterns 30 may be disposed on the second insulator 6.

[0089] In the above embodiment, the first insulator 5 and the second insulator 6 are both solvent-free UV-curable resins, but the first insulator 5 and the second insulator 6 may be made of a resin other than solvent-free UV-curable resin as long as they can be stacked on top of each other.

[0090] An example of carrying out the "method of forming a protrusion" in the above embodiment will be described below.

[0091] First, in the first step, a resin molded body made of acrylic resin was prepared to serve as the first insulator. A silane coupling agent was reacted with the upper surface of this resin molded body. The silane coupling agent used was A-1110 manufactured by Momentive Corporation. As a result, silyl groups were introduced into the main chain and side chain of the polymer of the acrylic resin that constitutes the resin molded body, turning it into a silicone-modified acrylic resin. SEM images of the upper surface of the resin molded body that became silicone-modified acrylic resin are shown in Figures 12 and 13.

[0092] Next, in the second step, the upper surface of the resin molded body was exposed to O ２The resin molded body was subjected to plasma treatment, and the vicinity of the upper surface thereof was partially vaporized. SEM images of the upper surface of the resin molded body whose vicinity of the upper surface had been partially vaporized are shown in FIGS. 14 and 15.

[0093] O shown in FIGS. ２ Compared with before the plasma treatment, the O ２ In the resin molded body after the plasma treatment, the ratios (molar ratios) of the main atoms constituting the upper surface of the resin molded body changed as shown in Table 1. The atomic ratios shown in Table 1 were measured by subjecting the upper surface of the resin molded body to surface elemental analysis by X-ray photoelectron spectroscopy (XPS).

[0094]

[0095] As can be seen from Table 1, O ２ By performing the plasma treatment, the ratio of Si atoms increased by about 3 times, and the ratio of O atoms increased by about 2.6 times.

[0096] In addition, O ２ When plasma treatment was performed for only 3 minutes, and ２ CF instead of plasma treatment ４ When plasma treatment was performed, no increase in the ratio of Si atoms or the ratio of O atoms was observed in either case.

[0097] The present disclosure is industrially applicable as a conductive member.

[0098] 1: Multilayer wiring board (conductive film) 2: Mounting element 3: Substrate 4: Film base material 5: First insulator 5a: Adhesive portion 5b: Protruding portion 5c: Flat portion 6: Second insulator 7: First groove portion 7a: Bottom surface (first bottom surface) 7b: Side surface (first side surface) 7c: Corner portion 8: Second groove portion 8a: Bottom surface (second bottom surface) 8b: Side surface (second side surface) 8c: Corner portion 13: First thin metal wire 131: Adhesion layer 132: Conductive layer (first conductive layer) 17: Second thin metal wire 171: Adhesion layer 172: Conductive layer (second conductive layer) 20: Overlapping pattern 21: Connection region 22: Via portion 30: Dummy pattern 31: Dummy conductive line P: Intersection D1: Angle (first angle) D2: Angle (second angle) L1: Thickness (first thickness) L2: Thickness (second thickness) W1: Groove width (first groove width) W2: Groove width (second groove width)

Claims

1. A semiconductor device comprising: a sheet-like first insulator having a plurality of protrusions on its upper surface; a first groove formed on the upper surface of the first insulator; a first thin metal wire arranged along the first groove; and a sheet-like second insulator laminated directly on the first insulator, wherein the plurality of protrusions are made of SiO ２ the plurality of protrusions protrude upward, and the plurality of protrusions penetrate into the second insulator.

2. The conductive film according to claim 1, wherein the first insulator contains Si atoms, and the Si content of the first insulator is higher than the Si content of the second insulator.

3. The conductive film according to claim 2, wherein the first insulator has a flat portion in contact with the second insulator, and in the flat portion, the first insulator is bonded to the second insulator via Si atoms.

4. The conductive film according to any one of claims 1 to 3, wherein the first insulator includes a resin material containing a polymer having a silyl group.

5. The conductive film according to any one of claims 1 to 4, further comprising: a second groove portion formed on the upper surface of the second insulator; and a second thin metal wire arranged along the second groove portion.

6. A conductive film according to claim 5, wherein the first groove portion has a first bottom surface located below the first thin metal wire and a first side surface located to the side of the first thin metal wire and connected to the first bottom surface, the second groove portion has a second bottom surface located below the second thin metal wire and a second side surface located to the side of the second thin metal wire and connected to the second bottom surface, the angle formed between the second side surface and the second bottom surface being larger than the angle formed between the first bottom surface and the first side surface, and the conductive film is transparent.

7. A conductive film as described in claim 6, wherein the first thin metal wire has a first adhesive layer covering the inner surface of the first groove portion and a first conductive layer disposed on the first adhesive layer, the second thin metal wire has a second adhesive layer covering the inner surface of the second groove portion and a second conductive layer disposed on the second adhesive layer, and the thickness of the second adhesive layer at the second bottom surface is greater than the thickness of the first adhesive layer at the first bottom surface.

8. The conductive film according to claim 6, further comprising: a first blackening layer laminated on the upper surface of the first thin metal wire; and a second blackening layer laminated on the upper surface of the second thin metal wire, wherein the thickness of the first blackening layer is greater than the thickness of the second blackening layer.

Images