Electrical component

Abstract

The purpose of the present invention is to make it possible for light emitted from a light source to illuminate a more appropriate area in an electrical component that comprises an electrostatic switch. An electrical component according to the present invention comprises a base material layer, an electroconductive layer, an electrostatic switch electrode, a light source, a lightguide layer, a reflection layer, and a light-blocking wall. The base material layer includes a first region and a translucent second region that is a different region from the first region. The electroconductive layer is provided to the first region of the base material layer. The electrostatic switch electrode is translucent and is provided to the second region of the base material layer. The light source is installed on the electroconductive layer. The light guide layer is provided so as to cover a region that goes from the light source to the electrostatic switch electrode. The reflection layer is provided on the opposite side of the lightguide layer from the base material layer. The light-blocking wall surrounds the side of the lightguide layer.

Description

Electrical equipment

[0001] The present disclosure relates to electrical equipment.

[0002] Patent Document 1 discloses an electronic device having a backlight illumination structure. In the backlight illumination structure described in Patent Document 1, a light-emitting diode is provided on the inner surface of the electronic device. The light-emitting diode is configured to emit light toward the opposite side of the electronic device from the outer surface, and the reflected light illuminates an indicator on the outer surface of the electronic device.

[0003] Japanese Patent Application Laid-Open No. 2020-96188

[0004] In the backlight illumination structure described in Patent Document 1, there is a risk that light emitted from the light emitting diodes may leak out to the sides of the electronic device.

[0005] Therefore, an object of the present invention is to enable light emitted from a light source to illuminate a more appropriate range in an electrical component equipped with an electrostatic switch.

[0006] The electrical equipment disclosed herein is an electrical equipment comprising: a base layer including a first region and a second region different from the first region and having translucency; a conductive layer provided in the first region of the base layer; a translucent electrostatic switch electrode provided in the second region of the base layer; a light source mounted on the conductive layer; a light-guiding layer provided to cover the region from the light source to the electrostatic switch electrode; a reflective layer provided on the opposite side of the base layer from the light-guiding layer; and a light-shielding wall surrounding the sides of the light-guiding layer.

[0007] According to the present disclosure, in an electrical component including an electrostatic switch, the light emitted from the light source can illuminate a more appropriate range.

[0008] FIG. 1 is a plan view showing an electrical component according to a first embodiment. FIG. 2 is a side view showing an electrical component according to a first embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is an enlarged view of area A1 in FIG. 3. FIG. 5 is a diagram showing a process for manufacturing the electrical component. FIG. 6 is a diagram showing a process for manufacturing the electrical component. FIG. 7 is a diagram showing a process for manufacturing the electrical component. FIG. 8 is a diagram showing a process for manufacturing the electrical component. FIG. 9 is a diagram showing evaluation results of samples.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] The electrical equipment of the present disclosure is as follows.

[0011] (1) An electrical device comprising: a base layer including a first region and a second region different from the first region and having translucency; a conductive layer provided in the first region of the base layer; a translucent electrostatic switch electrode provided in the second region of the base layer; a light source mounted on the conductive layer; a light-guiding layer provided to cover a region from the light source to the electrostatic switch electrode; a reflective layer provided on the opposite side of the base layer from the light-guiding layer; and a light-shielding wall surrounding the sides of the light-guiding layer.

[0012] According to the electrical equipment of (1), in the electrical equipment, light emitted from the light source is reflected by the reflective layer and reaches a user outside the electrical equipment through the light guide layer, the electrostatic switch electrode, and the second region of the base layer. The user's recognition of this light makes it easier to recognize the position of the electrostatic switch electrode. By providing a light-shielding wall in the electrical equipment, it is possible to prevent light emitted from the light source and passing through the light guide layer from leaking to the side of the light guide layer. This allows the light emitted from the light source to illuminate a more appropriate range in an electrical equipment equipped with an electrostatic switch.

[0013] (2) In the electrical equipment of (1), the reflective layer may be made of resin, which allows the dimensions of the electrical equipment in the stacking direction to be smaller than when an air layer as a reflective layer and a resin layer covering the air layer are provided separately.

[0014] (3) In the electrical equipment of (2), the entire portion of the light guide layer that contacts the surface opposite to the base layer may be the reflective layer. This makes it easier for the reflective layer to diffusely reflect light, reducing unevenness in the light passing through the second region. This makes it easier for the second region to emit light from a clear surface.

[0015] (4) In the electrical equipment of any one of (1) to (3), the light-shielding wall and the reflective layer may be formed from a single resin part, thereby reducing the number of parts compared to when the light-shielding wall and the reflective layer are formed from different resin parts.

[0016] (5) In the electrical equipment of (4), the resin part may be a resin molded part that is insert-molded using a circuit component having the base layer, the conductive layer, the electrostatic switch electrode, the light source, and the light guide layer as an insert. This makes it easier to form the surface of the resin part facing the light guide layer into a shape that conforms to the light guide layer, compared to when the resin part is a separately molded part.

[0017] (6) In the electrical equipment of any one of (1) to (5), the conductive layer may be a coating formed of a conductive paste, and the light source may be mounted on the conductive layer with a conductive adhesive. This makes it easy to set the coating to a material that is easy to stretch, even when a circuit component having a conductive paste coating provided on a base layer is three-dimensionally molded.

[0018] (7) In the electrical equipment of any one of (1) to (5), the conductive layer may be a coating formed of a conductive paste, and the light source may be mounted on the conductive layer by low-temperature soldering. This reduces the resistance applied to the light source circuit compared to when the light source is mounted by a conductive adhesive.

[0019] [Details of the embodiment of the present disclosure] Specific examples of electrical equipment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0020] [First Embodiment] An electrical component according to a first embodiment will now be described. Fig. 1 is a plan view showing an electrical component 10 according to the first embodiment. Fig. 2 is a side view showing the electrical component 10 according to the first embodiment. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. Fig. 4 is an enlarged view of an area A1 in Fig. 3. Arrow A2 in Fig. 4 indicates the path of light emitted from the light source 50. Figs. 5 to 8 are diagrams showing the manufacturing process of the electrical component 10. Each figure shows three mutually orthogonal directions: an X direction, a Y direction, and a Z direction.

[0021] The electrical equipment 10 includes a base layer 20, a conductive layer 30, a static switch electrode 40, a light source 50, a light guide layer 60, a reflective layer 72, and a light-shielding wall 74. The conductive layer 30 and the static switch electrode 40 are provided on the base layer 20. The light source 50 is mounted on the conductive layer 30. The light guide layer 60 is provided so as to cover the area from the light source 50 to the static switch electrode 40. The reflective layer 72 is provided on the side of the light guide layer 60 opposite the base layer 20. The light-shielding wall 74 surrounds the side of the light guide layer 60.

[0022] Here, the reflective layer 72 and the light-shielding wall 74 are configured by a single resin part 70. Here, the resin part 70 is a resin molded part 70 that is insert-molded using the circuit component 12, which includes the base layer 20, the conductive layer 30, and the light source 50, as an insert. The light source 50 is an example of an electronic element, such as a light-emitting diode (LED). Hereinafter, the light source 50 may be referred to as an LED 50. Hereinafter, the light guide layer 60 is also referred to as an insert. The resin part 70 is a resin molded part 70 that is insert-molded using the circuit component 12, which includes the base layer 20, the conductive layer 30, the electrostatic switch electrode 40, the light source 50, and the light guide layer 60, as an insert.

[0023] The electrical component 10 is, for example, a touch panel device. The electrical component 10 is mounted on a vehicle such as an automobile. Here, the electrical component 10 is an interior component in which an electronic circuit for an automobile and a resin molded portion 70 are integrally molded. In the vehicle, the electrical component 10 may be mounted on, for example, an instrument panel. The resin molded portion 70 may constitute a part of the instrument panel.

[0024] The touch panel device includes an operation switch unit and a backlight illumination unit. The portion including the electrostatic switch electrode 40 constitutes the operation switch unit. The portion including the light source 50 constitutes the backlight illumination unit. As shown in FIG. 2 , the outer surface of the operation switch unit constitutes an operation surface that a user touches with a finger UF or the like. The electrostatic switch electrode 40 is located inside the operation surface. The backlight illumination unit illuminates the operation surface from the inside, making it easier for the user to see the operation surface. Here, the backlight illumination unit illuminates the operation switch unit by reflecting light emitted from the light source 50 toward the side opposite the second surface 22 with the reflective layer 72, as shown by arrow A2 in FIG. 4 . As shown in FIG. 1 , indicators 14 (also referred to as icons, etc.) may be formed on the operation surface to indicate the location to be touched by the user and the function assigned to the electrostatic switch electrode 40. The backlight illumination unit may illuminate the indicators 14.

[0025] The base layer 20 is formed in a film shape. The base layer 20 has a first surface 21 and a second surface 22 facing opposite each other. The first surface 21 is provided with a conductive layer 30, an electrostatic switch electrode 40, a light source 50, a light-guiding layer 60, and a resin part 70. The second surface 22 is the surface facing the user.

[0026] The base layer 20 is three-dimensionally molded. Three-dimensional molding here refers to processing a member having a flat shape (2D shape) into a three-dimensional shape (3D shape). Three-dimensional molding is performed using a mold, for example, by vacuum molding, high-pressure molding, or vacuum / pressure molding. During three-dimensional molding, bending and stretching of the member may occur when processing from a flat shape to a three-dimensional shape. Therefore, the member processed three-dimensionally has flexibility that allows it to accommodate bending and stretching. Here, as shown in FIG. 5 , the base layer 20 is processed from a flat shape extending in the XY plane to a three-dimensional shape that also extends in the Z direction. Here, the base layer 20 includes a main body portion 23 and an extension portion 24. The main body portion 23 has a three-dimensional shape. The three-dimensional shape of the main body portion 23 is not particularly limited and can be set as appropriate. Here, the main body portion 23 is formed in a shape in which the first surface 21 is concave and the second surface 22 is convex. The extension portion 24 extends laterally (in the X direction or the Y direction) from the outer edge of the main body portion 23. Here, the extension portion 24 is formed flat.

[0027] The base layer 20 includes a first region 25 and a second region 26. The first region 25 and the second region 26 are different regions. The first region 25 is a region where the conductive layer 30 is provided. The second region 26 is a region where the electrostatic switch electrode 40 is provided. The second region 26 is light-transmitting. The first region 25 may or may not be light-transmitting.

[0028] The base layer 20 includes a translucent base film layer 20A. As shown in FIG. 4 , the base layer 20 may include a decorative layer 20B laminated on the base film layer 20A. The decorative layer 20B is provided, for example, on the first surface 21 side of the base film layer 20A. The decorative layer 20B may have light-blocking properties. The decorative layer 20B is formed by painting the base film layer 20A with a light-blocking paint or printing with a light-blocking ink. The decorative layer 20B may be a single layer or multiple layers with different colors. For example, the base film layer 20A may extend over the entire base layer 20, and the decorative layer 20B may be provided in a partial region of the base film layer 20A. The portion of the base layer 20 where the decorative layer 20B is not provided on the base film layer 20A forms a second region 26. Here, the first region 25 is the portion of the base layer 20 where the decorative layer 20B is provided. The first region 25 may be a portion of the base layer 20 where the decorative layer 20B is not provided.

[0029] The thickness of the base film layer 20A is not particularly limited, but if the base film layer 20A is too thick, shape conformability will be poor, and if it is too thin, tearing, wrinkles, etc. In consideration of these, the thickness of the base film layer 20A may be, for example, 0.025 mm or more and 1 mm or less.

[0030] The base film layer 20A preferably has a predetermined heat resistance. In the electrical equipment 10, the base film layer 20A is subjected to heat, for example, when the wiring pattern is cured or when the resin part 70 is insert-molded. If the heat resistance of the base film layer 20A is too low, the heat may cause tears, wrinkles, or the like in the base film layer 20A. By ensuring that the base film layer 20A has a predetermined heat resistance, tears, wrinkles, and the like caused by heat during manufacturing can be suppressed.

[0031] The heat shrinkage rate at 120°C for 30 minutes in an air atmosphere may be used as an indicator of heat resistance. The 30-minute heat shrinkage rate simulates the conditions for the heat treatment applied to the base film layer 20A during the manufacturing process of the electrical component 10. The heat shrinkage rate of the base film layer 20A can be calculated by {(length of the base film layer 20A before heating - length of the base film layer 20A after heating) / length of the base film layer 20A before heating} × 100. The temperature before heating is room temperature. The length of the base film layer 20A after heating is the length of the base film layer 20A when it is returned to room temperature after being subjected to a 30-minute heat treatment at 120°C. The predetermined heat resistance of the base film layer 20A is preferably such that the heat shrinkage rate is 5% or less. A heat shrinkage rate of 5% or less facilitates the prevention of damage to the base film layer 20A during the manufacturing process of the electrical component 10. More preferably, the predetermined heat resistance of the base film layer 20A is a heat resistance that satisfies the above-mentioned thermal shrinkage rate of 3% or less.

[0032] The base film layer 20A may be a directional film having anisotropic stretchability, such as a uniaxially stretched film, or may be a film having isotropic stretchability, such as a biaxially stretched film. When the base film layer 20A is composed of a directional film, the heat shrinkage rate of the base film in both the MD (machine direction) and the TD (transverse direction) is preferably 5% or less, and more preferably 3% or less.

[0033] The surface of the base film layer 20A may be modified to improve adhesion to the conductive layer 30. Such surface modification may be performed by primer treatment, plasma irradiation, corona irradiation, UV irradiation, or the like.

[0034] The base film layer 20A is made of, for example, a resin, and the resin may include at least one selected from the group consisting of polyesters such as polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), syndiotactic polystyrene (SPS), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), polyethylene naphthalate (PEN), nylons such as polyamide (PA), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE), cycloolefin polymer (COP), and acrylic (PMMA).

[0035] The conductive layer 30 is laminated on the decorative layer 20B of the base material layer 20. The conductive layer 30 has a pattern for an LED and a pattern for an electrostatic switch electrode. The conductive layer 30 may have a pattern for a purpose other than the pattern for an LED and the pattern for an electrostatic switch electrode.

[0036] The electrostatic switch electrode 40 is light-transmitting. The electrostatic switch electrode 40 is laminated on the base film layer 20A of the base layer 20. A portion of the electrostatic switch electrode 40 extends to the first region 25 and is connected to the electrostatic switch electrode pattern. The electrostatic switch electrode 40 may be formed of a conductive polymer such as PEDOT:PSS (polyethylenedioxythiophene:polystyrenesulfonate). The electrostatic switch electrode 40 may be adjacent to the LED 50 in the direction along the second surface 22, or may be spaced apart from the LED 50.

[0037] The LEDs 50 are mounted on the LED pattern of the conductive layer 30. Light from the LEDs 50 passes through the electrostatic switch electrode 40 and the second region 26 and exits the electrical component 10. Here, the conductive layer 30 and the decorative layer 20B are located closer to the second surface 22 than the LEDs 50, so the light emitted from the LEDs 50 is prevented from directly passing through the electrostatic switch electrode 40 and the second region 26. The light emitted from the LEDs 50 is reflected by the reflective layer 72 and exits the electrical component 10 after passing through the electrostatic switch electrode 40 and the second region 26.

[0038] The LED 50 is mounted on the conductive layer 30 via a bonding layer 32. Here, the bonding layer 32 is a low-temperature solder 32. Therefore, the conductive layer 30 has good solder wettability. The electrical equipment 10 may also include electronic elements other than the LED 50. Such electronic elements may be, for example, resistors, capacitors, or control IC chips. It is preferable that such electronic elements are mounted using the same mounting method as the LED 50.

[0039] The low-temperature solder 32 is a solder with a melting point of 184 degrees Celsius or lower. The low-temperature solder 32 is, for example, a Sn—Bi system. By using the low-temperature solder 32 for the bonding layer 32, the heat applied to the base layer 20 during soldering can be reduced. The heating method for the low-temperature solder 32 is not particularly limited and can be set as appropriate. The heating method for the low-temperature solder 32 is preferably an instantaneous local heating method using an infrared laser. As a result, the heat applied to the base layer 20 is instantaneous and localized only at the mounting location, thereby suppressing damage to the base layer 20 due to heating (warping, tearing, etc.).

[0040] The conductive layer 30 is a coating formed from a conductive paste. The conductive paste is provided on the base layer 20 by printing. The printing method is not particularly limited, and may be, for example, screen printing, flexographic printing, Clavia printing, Clavia offset printing, inkjet printing, or dispenser printing. The conductive paste printed on the base layer 20 is heated and cured to form a coating. The method for curing the paste coating is not particularly limited, and may be, for example, drying in a hot air oven.

[0041] The conductive paste contains a metal filler and a thermoplastic resin binder. The metal type of the filler is, for example, silver, copper, or silver-coated copper powder. The filler and binder remain in the coating even after the conductive paste is heat-cured.

[0042] The conductive paste material may contain, in addition to filler and binder, solvent, additives, etc. The conductive paste may consist of filler, binder, solvent, and additive. Because the solvent volatilizes when a coating is formed by heating, the mass fraction of the solvent in the coating is smaller than the mass fraction of the solvent in the conductive paste. The entire amount of solvent may volatilize, and no solvent may remain in the coating. Due to the reduction of the solvent during heat curing, the mass fraction of the filler in the coating may change from the mass fraction of the filler in the conductive paste before heat curing, and may usually become larger.

[0043] The solvent enhances the fluidity of the conductive paste. Examples of the solvent include glycol-based, glycol ether-based, glycol ester-based, and ketone-based solvents. The solvent preferably contains at least one selected from the group consisting of glycol-based, glycol ether-based, glycol ester-based, and ketone-based solvents.

[0044] The additives may be, for example, a thixotropic agent, an anti-settling agent, an antioxidant, etc. The thixotropic agent is added to prevent sagging of the conductive paste and ensure smooth application. The anti-settling agent prevents the filler from settling. The antioxidant prevents the filler from oxidizing.

[0045] Here, the conductive layer 30 is three-dimensionally molded together with the base layer 20. Therefore, the conductive layer 30 also has flexibility that allows it to be bent and stretched. Regarding the thickness of the coating after the conductive paste has hardened, if the film thickness is too thin, the resistance value is likely to increase due to insufficient contact of the filler. Furthermore, if the film thickness is too thick, costs increase and shape conformability during three-dimensional molding decreases. In view of these, the thickness of the coating is preferably, for example, 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0046] Here, the LED 50 is mounted on the conductive layer 30 using low-temperature solder 32. Therefore, the conductive layer 30 has good solder wettability. The filler and binder in the conductive paste are blended to provide good three-dimensional molding processability and solder wettability.

[0047] Specifically, the filler has a flake or scale shape. The flake shape is, for example, a thin, flat plate shape. The scale shape is a shape in which the main surface of the flake shape is curved. In addition to the flake or scale shape, spherical shapes may also be mixed into the filler.

[0048] Regarding the average particle size of the filler, if the average particle size of the filler is too small, it is difficult to obtain good three-dimensional molding processability and solder wettability. The larger the average particle size of the conductive paste filler, the easier it is for the fillers to maintain contact with each other even when the conductive layer 30 is stretched during three-dimensional molding process, and the increase in resistance can be suppressed. Furthermore, the larger the average particle size of the filler, the more likely the filler will appear on the coating surface, resulting in good solder wettability. Furthermore, if the average particle size of the filler is too large, it will be more likely to clog the nozzle during printing, resulting in poor printability. The smaller the average particle size of the filler, the less likely it is to clog the nozzle during printing.

[0049] The average particle size of the multiple fillers can be determined by observing the cross section of the conductive layer 30 under a microscope. The cross section of the conductive layer 30 is, for example, a cross section along the stacking direction of the base layer 20 and the conductive layer 30. Five or more microscopic images are obtained from the cross section of the conductive layer 30. Each microscopic image is binarized to determine the particle size of all fillers in the image. The measured particle size of the filler is the maximum dimension of each filler in the cross section. The average value of the particle sizes of all fillers is the average particle size of the multiple fillers.

[0050] In consideration of the above two contradictory conditions, the average particle size of the filler is preferably 6 μm or more and 20 μm or less. When the average particle size of the filler is 6 μm or more, good three-dimensional molding processability and solder wettability are easily obtained. When the average particle size of the filler is 8 μm or more, even better three-dimensional molding processability and solder wettability are easily obtained. When the average particle size is 20 μm or less, the filler is less likely to clog the nozzle during printing. Therefore, the conductive paste can be printed well even by inkjet printing and dispenser printing.

[0051] The binder is made of a thermoplastic resin. Such a thermoplastic resin is preferably a thermoplastic resin having a hydroxyl group as a functional group. The presence of a highly reactive hydroxyl group improves the affinity between the binder and the filler, making it less likely for the interfacial breakdown between the binder and the filler to occur even when the cured coating is stretched. Furthermore, the binder also has excellent adhesion to the base layer 20. Furthermore, during the solder mounting process, when localized instantaneous heating is applied, the coating is heated above the softening temperature of the thermoplastic resin and softens, allowing the solder to penetrate into the coating, and the filler and the metal component of the solder tend to form an alloy layer.

[0052] Such thermoplastic resins may be, for example, phenoxy resin, hydroxy polyurethane resin, polyvinyl alcohol resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer resin, or the like.

[0053] The hydroxyl groups may be urethane-modified by reacting with an isocyanate. This imparts rubber elasticity to the cured coating, improving stretchability. A blocked isocyanate compound is preferred as the isocyanate. Because a urethane reaction does not occur below the dissociation temperature of the blocking agent, the storage stability of the conductive paste at room temperature is excellent. From the perspective of the drying and curing temperature of the conductive paste, the blocked isocyanate compound is preferably 3,5-dimethylpyrazole (DMP), diethyl malonate (DEM), or a DMP / DEM hybrid, which have a blocking agent dissociation temperature of 120°C or less. The isocyanate is preferably trimer-type hexamethylene diisocyanate or biuret-type hexamethylene diisocyanate, which have excellent flexibility, and more preferably biuret-type hexamethylene diisocyanate.

[0054] Regarding the mass fraction of the filler in the coating, if the mass fraction of the filler in the coating is too small, the resin component of the binder becomes too high, making it difficult for the filler and the metal component of the solder to form an alloy, and the solder becomes more likely to aggregate. If the mass fraction of the filler in the coating is too large, the resin component of the binder becomes too low, impairing flexibility and making it difficult to obtain flexibility that can withstand three-dimensional molding. In light of these factors, when mounting with low-temperature solder 32, the mass fraction of the filler in the coating is preferably 90 wt% or more and 97 wt% or less. This allows for both good solder wettability and flexibility that can withstand three-dimensional molding. Specifically, if the mass fraction of the filler in the coating is 90 wt% or more, the filler and the metal component of the solder easily form an alloy, making it difficult for the solder to aggregate, and making it easier to obtain good solder wettability. Furthermore, if the filler loading amount in the coating is 97 wt% or less, the resin component of the binder easily provides flexibility that can withstand three-dimensional molding. More preferably, the mass fraction of the filler in the coating is 94 wt % or more, which makes it easier to obtain better solder wettability.

[0055] The light-guiding layer 60 is partially provided in the switch illumination area of ​​the base layer 20, including the LED 50. The light-guiding layer 60 is made of a transparent resin. The resin may be a UV-curable resin or a thermosetting resin. Light-diffusing particles such as acrylic or silicone may be added to the transparent resin. The light-guiding layer 60 allows light to be emitted not only near the LED 50 but also over a wide area. Furthermore, the light-guiding layer 60 reduces brightness unevenness by increasing the distance between the reflective layer 72 and the operation switch. The thickness of the light-guiding layer 60 is greater than the thickness of the LED mounting portion and the electrostatic switch electrode 40. The light-guiding layer 60 surrounds the LED 50 on all four sides and below (the side opposite the base layer 20). The light-guiding layer 60 surrounds the electrostatic switch electrode 40 on all four sides and below (the side opposite the base layer 20). The light-guiding layer 60 has a portion that contacts the base layer 20.

[0056] Here, insert molding is performed after the LEDs 50 are mounted. The light guide layer 60 is provided after the LEDs 50 are mounted but before insert molding. The light guide layer 60 is interposed between the LEDs 50 and the resin part 70. During insert molding, molding heat and molding pressure are typically applied to the insert. The light guide layer 60 prevents the low-temperature solder 32 from melting due to the molding heat and molding pressure. This prevents the electronic elements including the LEDs 50 from peeling off from the conductive layer 30. The light guide layer 60 also protects the electronic elements including the LEDs 50 from the molding heat and molding pressure.

[0057] The reflective layer 72 reflects, toward the inside of the light-guiding layer 60, light emitted from the LEDs 50 that passes through the light-guiding layer 60 and strikes the surface of the reflective layer 72. Here, the light-shielding wall 74 is also formed of the same material as the reflective layer 72. Therefore, like the reflective layer 72, the light-shielding wall 74 also reflects, toward the inside of the light-guiding layer 60, light that passes through the light-guiding layer 60 and strikes the surface of the light-shielding wall 74.

[0058] The resin material of the resin parts 70 forming the reflective layer 72 and the light-shielding walls 74 preferably includes at least one selected from the group consisting of polypropylene resin (PP), polystyrene resin (PS), acrylonitrile butadiene styrene resin (ABS), polycarbonate resin (PC), polyvinyl chloride resin (PVC), and acrylic resin (PMMA). Furthermore, the resin parts 70 forming the reflective layer 72 and the light-shielding walls 74 are preferably white or translucent. It is more preferable that the resin parts 70 be white resin. When the resin parts 70 are white, the reflectivity is likely to be high, improving the luminous efficiency.

[0059] The resin part 70, which forms the reflective layer 72 and the light-shielding walls 74, surrounds the light guide layer 60. The light reflection effect at the interface between the light guide layer 60 and the resin part 70 reduces uneven light emission and suppresses light leakage to the outside. Here, the light guide layer 60 is covered on all four sides by the light-shielding walls 74. Furthermore, one main surface of the light guide layer 60 is covered by a reflective wall. Here, the entire portion of the light guide layer 60 in contact with the surface opposite the base layer 20 is made of a reflective layer 72 made of a white or translucent resin. Here, the light guide layer 60 is formed of a uniform material, and the surface material of the light guide layer 60 is also uniform. Similarly, the resin part 70 is formed of a uniform material, and the surface material of the resin part 70 is also uniform. Therefore, the combination of materials at the contact portion between the light guide layer 60 and the resin part 70 is uniform.

[0060] The resin part 70 is provided so as to fill the concave surface on the first surface 21 of the base layer 20. The resin part 70 also functions as a housing for the electrical component 10. As shown in Fig. 4 , the base layer 20 here has a third region 27 in contact with the light guide layer 60 and a fourth region 28 in contact with the resin part 70.

[0061] <Manufacturing Method> A manufacturing method for the electrical component 10 will be described.

[0062] First, as shown in Fig. 5, a base material layer 20 is prepared, which is provided with a base material film layer 20A and a decorative layer 20B. At this time, the base material layer 20 is in the form of a flat film having an area larger than that of the state when used as the electrical equipment 10. Then, a conductive paste is applied in a predetermined pattern to a first region 25 of the first surface 21 of the base material layer 20, where the decorative layer 20B is provided, and the pattern is heated and cured to form a coating that becomes the conductive layer 30. Furthermore, an electrostatic switch electrode 40 is formed in a second region 26 of the first surface 21 of the base material layer 20, where the decorative layer 20B is not provided.

[0063] Next, as shown in Figure 6, the base layer 20 and the conductive layer 30 are three-dimensionally formed. The three-dimensional forming is performed by vacuum forming, high-pressure forming, or vacuum / pressure forming. Here, the base layer 20 is three-dimensionally formed so that it has a main body portion 23 and an extension portion 24, and the first surface 21 of the main body portion 23 is concave and the second surface 22 is convex. The portion of the conductive layer 30 that overlaps the main body portion 23 is also three-dimensionally formed. After that, excess portions of the base layer 20 are cut off by Thomson punching or press punching.

[0064] Next, as shown in Fig. 7, electronic components (LEDs 50, resistors, capacitors, control IC chips, etc.) are mounted on the conductive layer 30 with low-temperature solder 32. Here, the LEDs 50 are mounted on the LED pattern with low-temperature solder 32. Mounting with low-temperature solder 32 is performed by a localized instantaneous heating method using an infrared laser or the like. In this way, the circuit components 12 are formed.

[0065] 8, the mounting portion of the LED 50 and the backlight display area formed by the LED 50 are molded with a transparent resin (thermosetting resin or UV-curable resin) to form the light guide layer 60. Here, the light guide layer 60 is provided in a portion including the periphery of the LED 50 and the periphery of the electrostatic switch electrode 40. In this way, the circuit component 12 with the light guide layer 60 is formed.

[0066] Next, the circuit component 12 with the light-guiding layer 60 is placed in a mold as an insert. Then, a flowable resin is poured into the mold to form the resin molded portion 70 that forms the light-shielding wall 74 and the reflective layer 72. This completes the electrical equipment 10 shown in FIG. 1 .

[0067] As shown in FIG. 1 , for example, the electrical component 10 is connected to a device 92 via a connection wiring 90. In the electrical component 10, a connection portion with the connection wiring 90 is provided on the extension portion 24. The connection portion may be provided at a position other than the extension portion 24. The connection wiring 90 is, for example, a flexible printed circuit board (FPC). The connection wiring 90 may be wiring other than an FPC. The device 92 is, for example, a control device such as an electronic control unit (ECU). The device 92 may be a device other than a control device.

[0068] Figure 9 shows the evaluation results for the samples. Nine samples were evaluated in Figure 9 . The nine samples were formed as follows: Silver paste and PEDOT:PSS were screen-printed onto a transparent substrate film to form a conductive layer 30 and electrostatic switch electrodes 40. Next, three-dimensional molding was performed using high-pressure molding, followed by Thomson punching. Next, LEDs 50 were mounted on the conductive layer 30 with low-temperature solder 32 using an infrared laser method. Next, LEDs 50 and electrostatic switch electrodes 40 were attached using transparent UV-curable resin to form a light-guiding layer 60. Next, a resin molded section 70 was formed using insert molding with white PC resin, with circuit components 12 with light-guiding layers 60 inserted. The nine samples were designed to differ from one another in at least one of the following characteristics: filler shape, filler content, or average particle size in the silver paste; all other conditions were the same.

[0069] In Figure 9, the area rated A is shown with fine sand, the area rated B is shown with coarse sand, and the area rated C is shown with no color. These A, B, and C ratings are evaluations of solder wettability. A, B, and C are ranked in order of superiority of solder wettability. The sample rated B showed superior solder wettability to the sample rated C. The sample rated A showed superior solder wettability to the sample rated B. The sample rated A showed particularly superior solder wettability among the samples tested. The boundaries between the A, B, and C rating areas were drawn based on the evaluation results of the samples.

[0070] As shown in Figure 9, six samples in which the filler was flaky, the filler content was 90 wt% or more, and the average filler particle size was 6 μm or more were rated B or higher. Of these, three samples in which the filler was flaky, the filler content was 94 wt% or more, and the average filler particle size was 8 μm or more were rated A. Two samples in which the filler was spherical, the filler content was 97 wt%, and the average filler particle size was less than 6 μm, and two samples in which the filler was flaky, the filler content was 84 wt%, and the average filler particle size was 6 μm or more were rated C.

[0071] <Effects, etc.> With the electrical equipment 10 configured as described above, as shown by arrow A2 in Fig. 4 , light emitted from the light source 50 is reflected by the reflective layer 72 and reaches a user outside the electrical equipment 10 through the light guide layer 60, the electrostatic switch electrode 40, and the second region 26 of the base layer 20. The user's recognition of this light makes it easier to recognize the position of the electrostatic switch electrode 40. By providing the light-shielding wall 74 in the electrical equipment 10, it is possible to prevent light emitted from the light source 50 and passing through the light guide layer 60 from leaking to the sides of the light guide layer 60. This allows the light emitted from the light source 50 to illuminate a more appropriate range in the electrical equipment 10 that includes an electrostatic switch.

[0072] If the switches installed in a vehicle are conventional mechanical switches, each switch requires the wiring of a covered electrical wire. In contrast, if the switches installed in a vehicle are touch panel devices like the electrical equipment 10, multiple switch functions can be integrated into a single electrostatic film sensor, resulting in weight reduction and space savings. Some touch panel devices have LEDs 50 mounted on the base layer 20, but rather have a PCB board with LEDs 50 laminated on the light-guiding layer 60. By mounting the LEDs 50 on the base layer 20, the electrical equipment 10 of the present disclosure can be made thinner than touch panel devices that have a PCB board with LEDs 50.

[0073] The reflective layer 72 is made of resin, which allows the dimensions of the electrical component 10 in the stacking direction to be smaller than when an air layer serving as the reflective layer 72 and a resin layer covering the air layer are provided separately.

[0074] Furthermore, the entire portion of the light guide layer 60 that is in contact with the surface opposite to the base layer 20 is the reflective layer 72. This makes it easier for the reflective layer 72 to diffusely reflect light, making it less likely that unevenness will occur in the light passing through the second region 26. This makes it easier for the second region 26 to emit clear surface light.

[0075] Furthermore, the light-shielding wall 74 and the reflective layer 72 are formed from a single resin part 70. This allows the number of parts to be reduced compared to when the light-shielding wall 74 and the reflective layer 72 are formed from different resin parts 70.

[0076] Furthermore, the resin part 70 is a resin molded part 70 that is insert-molded using the circuit component 12, which includes the base layer 20, the conductive layer 30, the electrostatic switch electrode 40, the light source 50, and the light guide layer 60, as an insert. This makes it easier to form the surface of the resin part 70 facing the light guide layer 60 into a shape that conforms to the light guide layer 60, compared to when the resin part 70 is a separately molded part. In particular, when three-dimensional molding is performed, a curved surface may be formed on the surface that comes into contact with the resin part 70. Because the resin part 70 is an insert-molded resin molded part 70, it is easy to ensure that the resin part 70 is in contact with the curved surface as a whole.

[0077] Furthermore, the conductive layer 30 is a coating formed from a conductive paste, and the light source 50 is mounted on the conductive layer 30 with low-temperature solder 32. This reduces the resistance value applied to the circuit of the light source 50 compared to when the light source 50 is mounted with a conductive adhesive.

[0078] Furthermore, the electrical equipment 10 also has the following advantages. Because the binder is made of a thermoplastic resin, when the coating is heated to above the softening temperature of the thermoplastic resin during the solder mounting process, the coating softens, allowing the solder to penetrate into the coating, facilitating the formation of an alloy layer between the filler and the solder metal component. Furthermore, because the average particle size is 20 μm or less, clogging of the conductive paste at the nozzle is suppressed when printing the conductive layer 30 using the conductive paste. Furthermore, because the filler loading amount in the coating is 97 wt% or less, the flexibility of the coating is easily ensured, and three-dimensional processability (stretchability) is enhanced. Furthermore, because the filler has a flake or scale shape, the average particle size of the filler is 6 μm or more, and the mass fraction of the filler in the coating is 90 wt% or more, the stretchability and solder wettability of the coating are enhanced, and an increase in the resistance value of the circuit via the low-temperature solder 32 can be suppressed even after three-dimensional molding and insert molding.

[0079] The average particle size of the filler is 8 μm or more, which can further suppress an increase in resistance when the conductive layer 30 is stretched by three-dimensional molding, and also improve solder wettability.

[0080] The mass fraction of the filler in the coating is 94 wt % or more. This reduces the mass fraction of the binder in the coating, making it easier for the filler to form an alloy with the metal components of the low-temperature solder 32, and making it difficult for the low-temperature solder 32 to aggregate.

[0081] The thermoplastic resin constituting the binder also has hydroxyl groups. As a result, the hydroxyl groups have good affinity with the metal filler, so that even if the conductive layer 30 is stretched during three-dimensional molding, the interface between the binder and the filler is less likely to break down. Furthermore, because the hydroxyl groups are highly reactive, good adhesion between the binder and the base layer 20 is easily achieved.

[0082] [Additional Note] In the first embodiment, the bonding layer 32 on which the LED 50 is mounted is described as being made of low-temperature solder 32, but this is not a required configuration. The bonding layer 32 on which the LED 50 is mounted may be made of a material other than low-temperature solder 32, such as a conductive adhesive. When the bonding layer 32 is made of a conductive adhesive, the conductive layer 30 does not need to have solder wettability. Therefore, even when three-dimensionally molding a circuit component 12 in which a conductive layer 30 made of a conductive paste coating is provided on a base layer 20, it is easy to select a material for the coating that is easy to stretch. In other words, it is possible to consider stretchability and electrical connectivity after stretching without considering solder wettability, thereby broadening the range of material selection.

[0083] Such conductive adhesive may be, for example, Ag-based or Ni-based. In the case of conductive adhesive mounting, since solder wettability is not required, the average particle diameter of the filler may be smaller than 6 μm. For example, in the case of conductive adhesive mounting, the average particle diameter of the filler is preferably 1 μm or more.

[0084] In the case of conductive adhesive mounting, since solder wettability is not required, the particle shape may be a shape other than flake or scale shape. In the case of conductive adhesive mounting, the particle shape may include at least one shape selected from the group consisting of spherical, flake, dendritic, and scale shapes.

[0085] Even when a conductive adhesive is used, it is preferable that the filler have an average particle size of 5 μm or more and that the filler particles have a flake or scale-like shape in order to suppress an increase in resistance when the conductive layer 30 is stretched during three-dimensional molding. When the filler has an average particle size of 5 μm or more and that the filler particles have a flake or scale-like shape, the filler particles are more likely to come into surface contact with each other. Therefore, even when the conductive layer 30 is stretched, contact points between the filler particles are more likely to be secured, making it easier to suppress an increase in resistance.

[0086] In the case of conductive adhesive mounting, since solder wettability is not required, the mass fraction of the filler in the coating may be 90 wt% or less. For example, the mass fraction of the filler in the coating may be 70 wt% to 95 wt%, or 80 wt% to 90 wt%. If the filler loading is too low, the resistance will be high, and if it is too high, flexibility will be impaired.

[0087] Alternatively, the light guide layer 60 and the resin part 70 may face each other with a gap therebetween. An air layer may be provided between the light guide layer 60 and the resin part 70. The air layer may be the reflective layer 72.

[0088] The configurations described in the above embodiments and modifications can be combined as appropriate as long as they are not mutually contradictory.

[0089] REFERENCE SIGNS LIST 10 Electrical equipment 12 Circuit component 20 Base material layer 20A Base material film layer 20B Decorative layer 21 First surface 22 Second surface 23 Main body portion 24 Extension portion 25 First region 26 Second region 27 Third region 28 Fourth region 30 Conductive layer 32 Bonding layer (low-temperature solder) 40 Electrostatic switch electrode 50 LED (light source, electronic element) 60 Light-guiding layer 70 Resin part (molded resin part) 72 Reflective layer 74 Light-shielding wall 90 Connection wiring 92 Device UF finger

Claims

1. An electrical device comprising: a base layer including a first region and a second region different from the first region and having translucency; a conductive layer provided in the first region of the base layer; a translucent electrostatic switch electrode provided in the second region of the base layer; a light source mounted on the conductive layer; a light-guiding layer provided so as to cover the region from the light source to the electrostatic switch electrode; a reflective layer provided on the opposite side of the base layer from the light-guiding layer; and a light-shielding wall surrounding the sides of the light-guiding layer.

2. An electrical component according to claim 1, wherein the reflective layer is made of resin.

3. An electrical device according to claim 2, wherein the entire portion of the light-guiding layer that contacts the surface opposite to the base material layer is the reflective layer.

4. An electrical component according to any one of claims 1 to 3, wherein the light-shielding wall and the reflective layer are formed from a single resin part.

5. An electrical equipment according to claim 4, wherein the resin part is a resin molded part that is insert-molded using a circuit component having the base layer, the conductive layer, the electrostatic switch electrode, the light source, and the light-guiding layer as an insert.

6. An electrical device according to any one of claims 1 to 3, wherein the conductive layer is a coating formed from a conductive paste, and the light source is mounted on the conductive layer with a conductive adhesive.

7. An electrical device according to any one of claims 1 to 3, wherein the conductive layer is a coating formed from a conductive paste, and the light source is mounted on the conductive layer by low-temperature soldering.

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