Conductive member, electrical connection member, and connection structure

Abstract

The objective of the present invention is to suppress transmission loss of electrical signals. An electrically conductive member 110 for conductively connecting a first connection target object and a second connection target object is provided with a polymer matrix 114 comprising a rubber-like resilient material, and an electrically conductive medium 112 that is electrically conductive, wherein: the electrically conductive medium comprises electrically conductive particles 112a arranged continuously in the conduction direction of the electrically conductive member; the surface roughness of the surface of the electrically conductive particles, expressed as an arithmetic mean height (Sa), is at most equal to 5 μm; and the surface roughness of the interface between the electrically conductive particles, expressed as a developed area ratio (Sdr), is at most equal to 20.

Description

[Technical Field]

[0001] The present disclosure relates to a conductive member, an electrical connection member, and a connection structure. [Background technology]

[0002] Automotive window glass, for example, is equipped with a defroster or defogger, so a power supply part consisting of a conductive layer is formed on the glass sheet, and this power supply part must be electrically connected to a terminal. Lead solder has been widely used to electrically connect the power supply part to the terminal, but with the expansion of lead regulations, an alternative to lead-free solder is required. However, lead-free solder has a melting point 20 to 45°C higher than lead solder, so it does not adhere well and is prone to peeling.

[0003] It is desirable to improve the adhesive strength of electrical connection members that electrically connect power supply units and terminals in on-board electrical components such as defrosters and defoggers using an alternative technique to soldering. Patent documents 1 to 3, for example, disclose electrical connection members that improve adhesive strength between objects to be connected. The electrical connection members in Patent documents 1 to 3 include a conductive member formed by incorporating a magnetic conductive filler such as nickel, cobalt, or iron into a rubber-like elastic body. The conductive member is then brought into contact with the object to be connected, and an adhesive member containing an adhesive holds the conductive member in a state compressed in the thickness direction, thereby achieving electrical connection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 075810 [Patent Document 2] International Publication No. 2020 / 203037 [Patent Document 3] International Publication No. 2020 / 218520 Summary of the Invention [Problem to be solved by the invention]

[0005] Antennas installed on windshields and other surfaces, which are essential in-vehicle electrical components, are used to receive radio waves for GPS and digital televisions, as well as to transmit and receive radio waves for high-speed communications. The terminals of these antennas are electrically connected to cables via electrical connection members. To accommodate the growing demand for high-frequency and high-speed communications, it is necessary to reduce transmission loss of electrical signals.

[0006] An object of one aspect of the present disclosure is to suppress transmission loss of an electrical signal. [Means for solving the problem]

[0007] One aspect of the present disclosure is a conductive member that electrically connects a first connection object and a second connection object, the conductive member comprising a polymer matrix made of a rubber-like elastic material and a conductive medium having electrical conductivity, the conductive medium being conductive particles arranged continuously along the direction of conduction of the conductive member, and the surface roughness of the conductive particles, expressed as the arithmetic mean height (Sa), is 0.1 to 5 μm.

[0008] According to one aspect of the present disclosure, the surface roughness, expressed by the arithmetic mean height (Sa), of the surface of the conductive particles used as the conductive medium in the conductive member is reduced to within a predetermined range, thereby smoothing the surface of the conductive medium through which current flows, thereby shortening the path through which the current flows and reducing transmission loss.

[0009] In one aspect of the present disclosure, the conductive particles may have a surface roughness of 0.1 to 20, which is expressed by a developed area ratio (Sdr) of the interface.

[0010] By reducing the surface roughness, expressed as the developed area ratio (Sdr) of the interface of the conductive particles, to within a predetermined range, the surface of the conductive medium through which the current flows becomes smooth, thereby shortening the path through which the current flows and reducing transmission loss.

[0011] In one aspect of the present disclosure, the conductive particles may have an average particle size of 10 to 300 μm.

[0012] By reducing the particle size of the conductive particles to a predetermined range in this way, the surface area of ​​the conductive medium increases, and the area of ​​the conductive path increases, making it easier for current to flow and reducing transmission loss of electrical signals.

[0013] In one aspect of the present disclosure, the conductive particles may be configured by coating the surface of magnetic particles with a conductive metal layer, and may be continuously arranged in the thickness direction of the conductive member and contained within the polymer matrix.

[0014] By connecting these fine conductive particles in a string-like pattern, numerous conductive paths are formed, which increases the conductive surface area, making it easier for current to flow and reducing transmission loss of electrical signals.

[0015] In one aspect of the present disclosure, the conductive metal layer may have a thickness of 0.1 to 4 μm.

[0016] This allows current in the high frequency range to flow more easily, particularly on the surface side of the conductive metal layer, thereby reducing transmission loss of electrical signals.

[0017] In one embodiment of the present disclosure, the specific surface area of ​​the magnetic particles is 10 to 800 cm 2 / g.

[0018] This allows current in the high frequency range to flow more easily, particularly on the surface side of the conductive metal layer, thereby reducing transmission loss of electrical signals.

[0019] In one aspect of the present disclosure, the conductive particles may be flaky conductive particles, and the conductive medium may be composed of a conductive coating containing the flaky conductive particles that coats the surface of the polymer matrix.

[0020] By using flaky conductive particles as the conductive particles in this way, even if the conductive coating made of the flaky conductive particles is stretched and deformed due to elastic deformation of the polymer matrix, the conductivity in the planar direction is easily maintained, thereby reducing the transmission loss of electrical signals.

[0021] Another aspect of the present disclosure is an electrical connection member that electrically connects a first connection object and a second connection object, comprising any of the conductive members described above, and a fixing member that holds the conductive member in a compressed state in the thickness direction while bringing the conductive member into contact with the first connection object and the second connection object.

[0022] According to another aspect of the present disclosure, by reducing the surface roughness of the conductive particles in the conductive member of the electrical connection member to within a predetermined range, the surface of the conductive medium through which current flows becomes smooth, thereby making it possible to suppress transmission loss of electrical signals.

[0023] Yet another aspect of the present disclosure is a connection structure configured by electrically connecting a first connection object and a second connection object with an electrical connection member, wherein any of the conductive members described above is fixed in a compressed state between the first connection object and the second connection object, thereby electrically connecting the first connection object and the second connection object with the electrical connection member.

[0024] According to yet another aspect of the present disclosure, by reducing the surface roughness of conductive particles in a conductive member provided in an electrical connection member that electrically connects a first connection object and a second connection object to within a predetermined range, the surface of a conductive medium through which a current flows becomes smooth, thereby making it possible to suppress transmission loss of an electrical signal. [Effects of the Invention]

[0025] According to one aspect of the present disclosure, transmission loss of an electrical signal can be reduced. [Brief explanation of the drawings]

[0026] [Figure 1]1 is a plan view showing a schematic configuration of an electrical connection member according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 1A is a cross-sectional view of a conductive member according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view of a conductive particle contained in the conductive member according to one embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view showing a modified example of a conductive member according to an embodiment of the present invention. [Figure 5] 1 is a cross-sectional view showing a schematic configuration of a connection structure according to an embodiment of the present invention. [Figure 6] 5A and 5B are explanatory diagrams showing the effects of the conductive member according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] A preferred embodiment according to one aspect of the present disclosure will be described in detail below. Note that the embodiment described below does not unduly limit the content of the present invention described in the claims, and not all of the configurations described in the embodiment are necessarily essential as means for solving the problems of the present invention.

[0028] Furthermore, in this specification and claims, when "first" and "second" are used, they are used to distinguish between different components, and are not used to indicate a particular order, superiority, or inferiority.

[0029] Furthermore, the "conductive member" and "electrical connection member" disclosed in this application electrically connect an adherend as a "first connection object" to an adherend as a "second connection object." Examples of the "first connection object" include various terminals provided on the glass surface, such as an antenna wiring terminal or a ground wiring terminal on a windshield or window glass. Examples of the "second connection object" include various terminals, such as a cable terminal or a terminal on a flexible substrate.

[0030] First, the outline of the configuration of an electrical connection member including a conductive member according to one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a plan view showing the outline of the configuration of the electrical connection member according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view taken along line AA in Fig. 1.

[0031] The electrical connection member 100 of this embodiment is provided so as to be capable of electrically connecting a first connection object and a second connection object that are arranged opposite each other in the vertical direction (height direction). Specifically, the electrical connection member 100 is configured to electrically connect, for example, an antenna wiring terminal (first connection object) such as a glass antenna or a film antenna to a cable terminal (second connection object) in a compressed state between them.

[0032] 1, the electrical connection member 100 includes a plurality of conductive members 110, fixing members 120, and a sheet-like connecting member 130 that connects the conductive members 110 and the fixing members 120. The conductive members 110 and the fixing members 120 are integrated by the connecting member 130 to form the electrical connection member 100.

[0033] The connecting member 130 is a planar sheet-like member, and is made of, for example, a resin sheet. As shown in FIG. 2, the connecting member 130 has a through hole 130a, and the conductive member 110 is inserted into the through hole 130a and fixed to the connecting member 130. Examples of resin sheets that can be used to form the connecting member 130 include polyethylene terephthalate (PET) sheets, polyethylene naphthalate sheets, polycarbonate sheets, polyether ether ketone sheets, polyimide sheets, polyamide sheets, polyethylene sheets, polypropylene sheets, and polyurethane sheets. Among these, PET sheets and polyimide sheets are preferred from the viewpoints of durability, heat resistance, and the like. The thickness of the connecting member 130 is, for example, 30 to 1000 μm, and preferably 50 to 350 μm. These thicknesses are particularly preferred from the viewpoints of durability, heat resistance, and other manufacturing requirements for on-board electrical components.

[0034] In the electrical connection member 100 of this embodiment, the conductive member 110 and the fixing member 120 are connected and integrated via the connecting member 130 made of a resin sheet, but the configuration may also be such that the connecting member 130 is not used. For example, the conductive member 110 and the fixing member 120 may be integrated by being attached to a sheet-like member such as a resin film, rubber film, mesh sheet, net, paper, woven fabric, nonwoven fabric, or foam sheet.

[0035] The fixing member 120 is a member that enables both sides of the electrical connection member 100 to be adhered to other components that are to be connected, and is made of, for example, an acrylic adhesive, a urethane adhesive, a silicone adhesive, a rubber adhesive, or the like. As shown in FIGS. 1 and 2 , the fixing member 120 is provided on the outer edges of the front and back sides of the connecting member 130. In this embodiment, the fixing member 120 is formed in a frame shape so as to surround the plurality of conductive members 110. Note that in FIG. 1 , the connecting member 130 is formed in a rectangular shape, and therefore the fixing member 120 is also formed in a rectangular frame shape to match that shape, but the shape of the fixing member 120 is not limited to a rectangular frame shape and may be other shapes.

[0036] In the electrical connection member 100 of this embodiment, such fastening members 120 are provided on the outer edges of the front and back sides of the coupling member 130. By providing the fastening members 120, the electrical connection member 100 has the function of holding the conductive member 110 in a state compressed in the thickness direction while bringing the conductive portion 112 of the conductive member 110 into contact with the first connection object and the second connection object. Therefore, by having the fastening members 120, the electrical connection member 100 can electrically connect the first connection object and the second connection object, while reliably and easily fixing the terminal to a mounting member (e.g., a glass plate) on which the connection object is provided.

[0037] The conductive member 110 includes a conductive portion 112 made of a conductive rubber-like elastic material and an insulating portion 114 made of a non-conductive rubber-like elastic material. More specifically, as shown in FIG. 2, the conductive rubber-like elastic material that makes up the conductive portion 112 contains a large number of conductive particles 112a that serve as conductive fillers within the rubber-like elastic material. The conductive particles 112a are preferably arranged so as to be continuous in the thickness direction of the electrical connection member 100. More preferably, the conductive particles 112a are magnetic and are arranged in a chain-like manner in the thickness direction by application of a magnetic field. By arranging the conductive particles 112a so as to be continuous in the thickness direction of the conductive member 110, the conductive member 110 can achieve low electrical resistance while reducing the compressive stress at 25% compression.

[0038] The conductive portion 112 is usually formed in a columnar shape. The cross-sectional shape of the columnar shape is not particularly limited and may be circular or polygonal, such as rectangular, but circular is preferable. A cylindrical insulating portion 114 is provided around the outer periphery of the columnar conductive portion 112, and the insulating portion 114 and the conductive portion 112 are integrated to form the conductive member 110. Note that the surface shape of the conductive portion 112 that comes into contact with the adherend may be a flat surface as shown in FIG. 2, a convex curved surface such as a dome, or a surface shape with small dotted or linear irregularities on the surface.

[0039] The insulating portion 114 is made of an insulating rubber-like elastic material. That is, the conductive member 110 is integrally formed from the rubber-like elastic material, and has conductive particles 112a arranged continuously in the thickness direction in its central portion, as shown in FIG. 2. Note that, as shown in FIG. 2, the conductive member 110 may have different outer diameters along the thickness direction. For example, as shown in FIG. 2, the conductive member 110 has smaller outer diameters at both end faces than the outer diameter of the portion between them. In this way, if the outer diameters of both end faces of the conductive member 110 are small, both end faces are more likely to be compressed along the thickness direction.

[0040] The electrical resistance of the conductive portion 112 when compressed by 25% is preferably 100 mΩ or less. If the electrical resistance is 100 mΩ or less, the conductive portion 112 is less likely to generate heat even when a large current is passed through it. From this perspective, the electrical resistance is more preferably 20 mΩ or less. Furthermore, due to restrictions on materials, etc., the electrical resistance is usually 0.1 mΩ or more. The electrical resistance when compressed by 25% can be obtained by passing a current generated by a constant current source through the conductive portion 112 while the conductive portion 112 is compressed by 25%, measuring the voltage, and calculating the electrical resistance value.

[0041] In this embodiment, the electrical connection member 100 has a plurality of conductive members 110. By providing a plurality of conductive members 110, a terminal (described later) is electrically connected to a connection target component such as a conductive layer via the plurality of conductive members 110. Therefore, even if a large current flows between the terminal and the connection target component, the electrical resistance of each conductive member 110 is kept low, which makes it easier to suppress temperature increases in the conductive members 110. Furthermore, by providing a plurality of conductive members 110, each conductive member 110 can be made smaller. Therefore, the load required to compress the entire plurality of conductive members 110 is reduced, making it less likely that the terminals will peel off due to the repulsive force of the conductive members 110.

[0042] As shown in FIG. 1, for example, the conductive members 110 are arranged in multiple rows (two rows in FIG. 1) of multiple conductive members 110 arranged in a single row. The spacing between the multiple conductive members 110 is preferably 0.5 mm to 200 mm, more preferably 1 mm to 50 mm. By keeping the spacing between the conductive members 110 within this range, insulation between adjacent conductive members 110 can be ensured without increasing the size of the electrical connection member 100 more than necessary. Note that the spacing between the conductive members 110 refers to the shortest distance between the conductive members 110 closest to each other. Furthermore, although the electrical connection member 100 of this embodiment includes four conductive members 110, the number of conductive members 110 is not limited to four.

[0043] As described above, the conductive particles 112a are preferably magnetic conductive fillers. Examples of the material of the magnetic conductive filler include nickel, cobalt, iron, ferrite, and alloys thereof, and examples of the shape of the magnetic conductive filler include particles, fibers, flakes, and thin wires. Furthermore, the magnetic conductive filler may be a highly conductive metal, resin, or ceramic coated with a magnetic conductor, or a magnetic conductor coated with a highly conductive metal. Examples of highly conductive metals include gold, silver, platinum, aluminum, copper, iron, palladium, chromium, and stainless steel.

[0044] The average particle size of the conductive particles 112a is preferably 1 to 200 μm, and more preferably 5 to 100 μm, in order to facilitate the formation of a chain state by application of a magnetic field and to efficiently form a conductor. In particular, in this embodiment, the average particle size of the conductive particles is preferably 10 to 300 μm in order to suppress transmission loss of electrical signals. The average particle size refers to the particle size at which the volume accumulation is 50% (D50) in the particle size distribution of the conductive filler determined by laser diffraction / scattering method. The conductive filler may be used alone or in combination of two or more types.

[0045] The filling rate of the conductive particles 112a in the conductive section 112 is, for example, 25 to 80% by volume, or preferably 30 to 75% by volume. By setting the filling rate of the conductive particles 112a within this range, it is possible to ensure conductivity while imparting a certain level of strength to the conductive section 112. The filling rate refers to the volume ratio of the conductive particles 112a to the total volume of the conductive section 112.

[0046] On the other hand, insulating section 114 does not usually contain conductive particles 112a, and the filling rate of conductive particles 112a in insulating section 114 is usually 0% by volume. However, insulating section 114 may contain a small amount of conductive particles 112a that are inevitably mixed in during the manufacturing process, etc., within a range that does not impair the insulating properties. Therefore, for example, the filling rate of conductive particles 112a in insulating section 114 may be less than 5% by volume, and preferably less than 1% by volume.

[0047] Examples of rubber-like elastic materials constituting the conductive portion 112 include thermosetting rubber and thermoplastic elastomer. Thermosetting rubber is rubber that hardens and crosslinks when heated, and specific examples include silicone rubber, natural rubber, isoprene rubber, butadiene rubber, acrylonitrile butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylic rubber, fluororubber, and urethane rubber. Of these, silicone rubber is preferred because of its excellent moldability, electrical insulation, and weather resistance.

[0048] Examples of the thermoplastic elastomer include styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, ester-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, fluorinated thermoplastic elastomers, ion-crosslinked thermoplastic elastomers, etc. The rubber-like elastomer may be used alone or in combination of two or more of the above-mentioned materials.

[0049] Furthermore, thermosetting rubber, thermoplastic elastomer, etc. may be used as the rubber-like elastic material that forms the polymer matrix that constitutes the insulating portion 114, and specific and preferred examples thereof are as described above. Similarly, the rubber-like elastic material that constitutes the insulating portion 114 may be used alone or in combination of two or more types. As described above, it is preferable that the rubber-like elastic materials that constitute the insulating portion 114 and the conductive portion 112 are integrally formed. Therefore, it is preferable that the rubber-like elastic materials that constitute the insulating portion 114 and the conductive portion 112 are of the same type, and it is more preferable that the rubber-like elastic materials that constitute both the insulating portion 114 and the conductive portion 112 are silicone rubber.

[0050] From the viewpoint of facilitating the alignment of the conductive filler in the thickness direction by applying a magnetic field or the like, the rubber-like elastic body is preferably a cured liquid rubber or a heat-meltable material. Note that the liquid rubber is liquid at room temperature (23°C) and normal pressure (1 atmosphere) before curing, and specific examples of the rubber include liquid rubbers listed as thermosetting rubbers, with liquid silicone rubber being preferred. Furthermore, examples of heat-meltable materials include thermoplastic elastomers.

[0051] The hardness of the conductive part 112 is preferably 30 to 87, more preferably 40 to 85, and even more preferably 60 to 80. By setting the hardness of the conductive part 112 within the above range, it becomes easier to adjust the compressive stress when the conductive member is compressed by 25% to within a desired range. From the same perspective, the hardness of the insulating part 114 is preferably 20 to 50, and more preferably 25 to 40. The hardness of the conductive part 112 is measured at 23°C using a type A durometer in accordance with "Vulcanized rubber and thermoplastic rubber - Determination of hardness - Part 3: Durometer hardness" described in JIS K6253-3:2012.

[0052] The diameter of the conductive portion 112 in the conductive member 110 is, for example, 1.0 to 6.0 mm. If the diameter of the conductive portion 112 is within the above-mentioned range, it becomes easier to keep the electrical resistance at 25% compression within a predetermined range. As a result, even if a large current flows between the upper and lower surfaces of the conductive member 110 during compression, the temperature rise of the conductive member 110 can be suppressed. From these perspectives, the diameter of the conductive portion 112 is preferably 1.0 to 3.0 mm, and more preferably 1.5 to 2.6 mm. Note that, when the diameter of the conductive portion 112 varies in the thickness direction, the diameter refers to the average value of the diameter of the conductive portion 112 on the upper surface and the diameter of the conductive portion 112 on the lower surface. Furthermore, in this specification, when the diameter is other than a circle, it can be calculated as the diameter of a circle having the same area as the conductive portion 112.

[0053] The diameter of the conductive portion 112 is preferably 35 to 97% of the diameter of the conductive member 110. By setting the diameter to 35% or more, electrical resistance can be sufficiently reduced, and by setting the diameter to 97% or less, appropriate elasticity can be imparted to the conductive member 110. From these viewpoints, the ratio of the diameter of the conductive portion 112 to the diameter of the conductive member 110 is more preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. Furthermore, the ratio of the diameter of the conductive portion 112 to the diameter of the conductive member 110 is more preferably 95% or less, and even more preferably 80% or less. By setting such a ratio, rubber elasticity can be easily maintained over a long period of time while allowing a large current to flow, thereby enabling more stable conduction. Note that when the diameter of the conductive member 110 varies in the thickness direction, the diameter refers to the average value of the diameter at the upper surface and the diameter at the lower surface.

[0054] The diameter of the conductive member 110 is not particularly limited, but is, for example, 1.1 to 8.0 mm, more preferably 1.1 to 6.0 mm, and even more preferably 1.8 to 5.0 mm. The thickness of the conductive member 110 is not particularly limited, but is preferably 0.2 to 1.5 mm, and more preferably 0.3 to 1.2 mm. By keeping the thickness within the above-mentioned range, the conductive member 110 is easily maintained in a compressed state by the fastening member 120. When the conductive member 110 is used while being maintained in a compressed state in the thickness direction, the compressibility is not particularly limited, but is, for example, 5 to 40%, more preferably 10 to 35%, and even more preferably 15 to 30%. The compressibility can be calculated using the formula (H0-H1) / H0, where H0 is the thickness of the conductive member 110 when no load is applied, and H1 is the thickness of the compressed conductive member 110 during use.

[0055] To manufacture the electrical connection member 100 of this embodiment having such a configuration, first, a mold consisting of an upper mold and a lower mold made of a non-magnetic material such as aluminum or copper is prepared. Pins made of a ferromagnetic material such as iron or a magnet are embedded in the upper and lower mold halves at positions corresponding to the conductive portions 112. One end of the pin is exposed on the cavity surfaces of the upper and lower mold halves.

[0056] Next, a resin sheet or the like for forming the connecting member 130 is prepared. The resin sheet may be prepared by punching or the like to form a plurality of through holes 130a. The resin sheet is inserted into the aforementioned mold in which the pins are embedded, and liquid rubber or molten thermoplastic elastomer, which is the raw material for the conductive member 110, is injected into the cavity. Magnetic conductive particles 112a are mixed into the liquid rubber in advance.

[0057] Then, a magnetic field is applied from above and below the mold using magnets. A parallel magnetic field connecting the pins is formed within the cavity, and the conductive particles 112a in the liquid rubber or the like are continuously aligned in the direction of the magnetic field lines. After this alignment, the upper and lower molds are completely clamped together and a heat treatment is performed to harden the liquid rubber, resulting in a sheet-like molded product in which the conductive member 110 and the resin sheet that constitutes the connecting member 130 are integrated. The fixing member 120 is then attached to the sheet-like molded product using a known method, thereby obtaining the electrical connection member 100 of this embodiment.

[0058] Next, the details of the configuration of a conductive member according to one embodiment of the present invention will be described with reference to the drawings. Fig. 3(A) is a cross-sectional view of a conductive member according to one embodiment of the present invention, and Fig. 3(B) is a cross-sectional view of a conductive member according to one embodiment of the present invention. Fig. 3(A) shows an enlarged view of part B in Fig. 2 mentioned above.

[0059] The conductive member 110 of this embodiment is formed by incorporating conductive particles 112a as a conductive medium into a polymer matrix, which is a rubber-like elastic body. In this embodiment, as shown in Fig. 3(A), the conductive member 110 includes conductive particles 112a in a region toward the center of the polymer matrix that constitutes the conductive member 110, forming a conductive portion 112. An insulating portion 114 that does not include conductive particles 112a is formed in a region that covers the outer peripheral surface of the conductive portion 112 of the polymer matrix that constitutes the conductive member 110.

[0060] That is, in this embodiment, the conductive particles 112a arranged continuously along the thickness direction of the conductive member 110 serve as a conductive medium to constitute the conductive portion 112 that conducts electricity between the first connection object and the second connection object. In other words, the thickness direction of the conductive member 110 is the direction of conduction by the conductive portion 112 of the conductive member 110. Therefore, when the conductive portion 112 of the conductive member 110 is compressed in the thickness direction of the conductive member 110, the surfaces of the conductive particles 112a arranged along the thickness direction come into contact with each other and are strung together like beads, thereby ensuring conductivity in the thickness direction of the conductive member 110.

[0061] In this embodiment, the conductive member 110 is characterized by reducing the surface roughness (Sa, Sdr) of the conductive particles 112a within a predetermined range, thereby reducing transmission loss in the high-frequency range. Specifically, the surface roughness expressed by the arithmetic mean height (Sa) of the conductive particle surface is set to 5 μm or less so as to be 0.1 to 5 μm, and the surface roughness expressed by the developed area ratio (Sdr) of the conductive particle interface is set to 20 or less so as to be 0.1 to 20. This is suitable for the conductive member 110 to be applicable to high-speed, large-capacity communications in the high-frequency range, such as 5G (fifth-generation mobile communications system). The arithmetic mean height (Sa) of the surface of the conductive particles 112a and the developed area ratio (Sdr) of the interface were measured in accordance with ISO 25178 by observing the surface of a metal plate using a laser microscope "Laser Microscope VK-X150" manufactured by Keyence Corporation at a 50x magnification (1200x magnification on the monitor).

[0062] 3(B), the conductive particles 112a are formed by coating the surfaces of magnetic particles 112a1 made of nickel, cobalt, iron, ferrite, or alloys thereof with conductive metal layers 112a2 made of electrically conductive metals such as gold, silver, platinum, aluminum, copper, iron, palladium, chromium, stainless steel, etc. To facilitate the flow of high-frequency current on the surface side of the conductive metal layer and reduce transmission loss of electrical signals, the thickness of the conductive metal layer is set to 0.1 to 4 μm, and the specific surface area of ​​the magnetic particles is set to 10 to 800 cm. 2In this embodiment, the surface roughness (Sa, Sdr) of the conductive particles 112a is set within a predetermined range by using magnetic particles 112a1 with high surface smoothness as the core material of the conductive particles 112a, or by performing a plating process that enhances surface smoothness when coating the surfaces of the magnetic particles 112a1 with the conductive metal layer 112a2.

[0063] Thus, in this embodiment, in order to reduce transmission loss of high-frequency electric signals, the surface roughness (Sa, Sdr) of the surface of the conductive particles 112a used as the conductive medium in the conductive member 110 is reduced within a predetermined range. Therefore, by reducing the surface roughness of the surface of the conductive particles 112a, the portion of the conductive particles 112a that serves as the conductive medium, along which current flows, becomes smooth. This shortens the path along which the electric current flows, thereby reducing transmission loss of the electric signal.

[0064] In this embodiment, the conductive member 110 is configured by including conductive particles 112a as a conductive medium in a polymer matrix that is a rubber-like elastic material, but the conductive medium may take other forms.

[0065] For example, as shown in FIG. 4 , the conductive particles in the conductive member 210 may be flake-shaped particles, and the conductive medium may be a conductive coating 212 containing the flake-shaped particles. That is, the conductive medium for establishing a conductive connection may be a conductive coating 212 that coats the surface of a rubber body 214 made of a rubber-like elastomer that forms a polymer matrix. Specifically, by applying a conductive ink to the surface (top, side, and bottom) of the rubber body 214, a conductive coating 212 made of flake-shaped particles is formed, and conductive flake-shaped conductive particles having conductivity are continuously provided along the surface of the rubber body 214. That is, in this embodiment, by applying the conductive coating 212 to the surface of the rubber body 214 of the conductive member 210, the flake-shaped particles are provided along the surface of the rubber body 214. Therefore, the direction along the surface of the rubber body 214 is the conduction direction of the conductive coating 212 that functions as the conductive portion of the conductive member 210.

[0066] With flaky conductive particles, even when the conductive coating 212 is stretched or deformed, conductivity in the planar direction is likely to be maintained, making it easier for current to flow on the surface and reducing transmission loss of electrical signals. Furthermore, with flaky conductive particles, the volume (electrical) resistivity of the conductive coating 212 can be made low even when the loading amount relative to the polymer substrate is relatively small. Therefore, in the conductive member 210, the loading amount of flaky conductive particles relative to the polymer substrate can be reduced, thereby reducing the difference between the modulus of elasticity of the conductive coating 212 and the modulus of elasticity of the rubber body 214 that serves as the substrate. Furthermore, with flaky conductive particles, the change in resistivity when the conductive coating 212 stretches or shrinks can be reduced.

[0067] Therefore, it is preferable to use a material with a large aspect ratio, such as a scale or fiber shape, rather than a spherical shape, for the conductive powder used in the conductive member 210. Examples of materials for the flake-shaped conductive particles include metals such as gold, silver, copper, nickel, iron, and tin, as well as carbon / graphite. In the conductive member 210, the flake-shaped conductive particles have an aspect ratio of 2 or more and an average particle size of 1 to 500. μm, preferably The thickness is preferably 5 to 70 μm. This allows the conductive coating 212 to maintain conductivity in the planar direction even when it is stretched and deformed. It is also preferable that the flaky conductive particles are oriented along the planar direction of the surface of the conductive coating 212. This allows the electrical conductivity in the orientation direction to be increased.

[0068] Next, the configuration of a connection structure using an electrical connection member 100 including a conductive member 110 according to one embodiment of the present invention will be described with reference to the drawings. Fig. 5 is a cross-sectional view showing a schematic configuration of a connection structure according to one embodiment of the present invention.

[0069] The connection structure 10 of this embodiment is configured to electrically connect the first connection object 12 and the second connection object 14 by providing an electrical connection member 100 between the first connection object 12 and the second connection object 14 that are arranged opposite each other in the vertical direction (height direction, thickness direction). Specifically, the connection structure 10 is configured such that a conductive member 110 of the electrical connection member 100 provided between, for example, an antenna wiring terminal such as a glass antenna or a film antenna that serves as the first connection object 12 and a cable terminal that serves as the second connection object 14 is fixed in a compressed state. The connection structure 10 is configured such that the antenna wiring terminal and the cable terminal are electrically connected by fixing the conductive member 110 in a compressed state.

[0070] In the connection structure 10 of this embodiment, the electrical connection member 100 is disposed between the first connection object 12 and the second connection object 14. At this time, both end faces of the conductive portions 112 of each conductive member 110 of the electrical connection member 100 are in contact with the first connection object 12 and the second connection object 14, respectively. Therefore, the first connection object 12 is connected to the second connection object 14 via the plurality of conductive portions 112. As shown in FIG. 5 , the electrical connection member 100 has an upper surface of the fastening member 120 bonded to the first connection object 12, and a lower surface of the fastening member 120 bonded to the second connection object 14. By bonding the electrical connection member 100 in this manner, the first connection object 12 is fixed to the second connection object 14, thereby establishing a conductive connection.

[0071] At this time, each conductive member 110 comes into contact with the first connection object 12 and the second connection object 14 in a compressed state. When each conductive member 110 is compressed, its conductivity increases and it is urged by a repulsive force toward the first connection object 12 and the second connection object 14, thereby enabling a more reliable connection between the first connection object 12 and the second connection object 14. Furthermore, when urged by a repulsive force, the first connection object 12 is likely to peel off from the second connection object 14. However, in the connection structure 10 of this embodiment, the first connection object 12 is reliably fixed to the second connection object 14 by the fixing member 120, making peeling less likely to occur. Note that each conductive member 110 may be compressed by, for example, 5 to 40%, more preferably 10 to 30%, and even more preferably 15 to 30%. Moreover, the surface of the first connection object 12 that comes into contact with the plurality of conductive members 110 is preferably flat so that the plurality of conductive members 110 can be easily compressed uniformly.

[0072] As described above, in this embodiment, the surface roughness of the conductive particles 112a in the conductive member 110 included in the electrical connection member 100 that electrically connects the first connection object 12 and the second connection object 14 is reduced to within a predetermined range. By reducing the surface roughness to within the predetermined range, the surfaces of the conductive particles 112a, which serve as a conductive medium through which current flows, become smooth, thereby suppressing transmission loss of electrical signals. Furthermore, since the conductive portions 112, which are aggregates of the conductive particles 112a, have low resistance, the conductive member 110 including such low-resistance conductive portions 112 can obtain the required conductivity (low resistance) in each of the conductive portions 112 even when a small pressure load is applied.

[0073] Therefore, the electrical connection member 100 including a plurality of such conductive members 110 can achieve a further reduction in the load on the electrical connection. As a result, the electrical connection member 100 can ensure the required conductivity at a low load even when including a plurality of conductive members 110. Therefore, the electrical connection member 100 can reduce the stress load at the connection portion between the first connection object 12 and the second connection object 14 via each conductive member 110. In particular, the electrical connection member 100 of this embodiment is more preferable as an electrical connection member for connecting electrical components for vehicles, which require durability at the connection portion between the first connection object 12 and the second connection object 14.

[0074] In the above description of the connection structure 10, an example was described in which the electrical connection member 100 including the conductive member 110 according to the first embodiment is used, but the same applies to cases in which electrical connection members including conductive members 210 of other aspects are used, so a description thereof will be omitted. The electrical connection member 100 of this embodiment can also be used for electrical connection to antennas, camera heaters, wiper heaters, backlights, sensors such as rain sensors, and even solar cells on a glass plate having a conductive connection portion on the glass plate.

[0075] Next, the functions and effects of the conductive member 110, the electrical connection member 100, and the connection structure 10 according to one embodiment of the present invention will be described with reference to the drawings. Figures 6(A) and 6(B) are explanatory diagrams of the functions and effects of the conductive member according to one embodiment of the present invention.

[0076] In this embodiment, the conductive member 110 is characterized in that the surface roughness (Sa, Sdr) of the surface of the conductive particles 112a in the conductive member 110 is reduced to within a predetermined range in order to accommodate high-speed, large-capacity communications in the high-frequency band. Specifically, the surface roughness expressed by the arithmetic mean height (Sa) of the conductive particle surface is set to 5 μm or less so as to be 0.1 to 5 μm, and the surface roughness expressed by the developed area ratio (Sdr) of the conductive particle interface is set to 20 or less so as to be 0.1 to 20.

[0077] In this way, the surface roughness (Sa, Sdr) of the conductive particles 112a used as the conductive medium in the conductive member 110 is reduced within a predetermined range, and the surfaces of the conductive particles 112a, which serve as the conductive medium through which current flows, are smoothed. By smoothing the surfaces of the conductive particles 112a, the path through which the current flows is shortened, thereby reducing the transmission loss of the electrical signal. Furthermore, because the contact surfaces between the conductive particles 112a that make up the conductive portion 112 of the conductive member 110 are smoothed, the conductive particles 112a that are continuous in the thickness direction of the conductive member 110 change from point contact to area contact, thereby stabilizing the conductive connection between the conductive particles 112a.

[0078] When the surface of the conductive particles 112a serving as the conductive medium is uneven, specifically, when the depth d1 of the unevenness on the surface of the conductive particles 112a is greater than the skin depth d of the conductive particles 112a as shown in FIG. 6(A), the effective path along which the current flows becomes longer. This attenuates the signal strength, resulting in increased transmission loss. In particular, as the frequency increases, which is the frequency range required for high-speed, large-capacity communications, current tends to concentrate on the surface of the conductor serving as the conductive medium, and the unevenness of the conductor surface has a significant impact on transmission loss. In other words, the greater the unevenness on the surface of the conductive particles 112a serving as the conductive medium, the greater the transmission loss.

[0079] Therefore, in this embodiment, in order to reduce transmission loss of electrical signals in the high-frequency range, as shown in FIG. 6(B), the surface smoothness of the conductive particles 112a is ensured so that the surface roughness depth d2 of the conductive particles 112a is less than the skin depth d of the conductive particles 112a. In this embodiment, the surface roughness (Sa, Sdr) of the conductive particles 112a in the conductive member 110 is reduced to within a predetermined range. By configuring the surfaces of the conductive particles 112a to be smooth enough to be less than the skin depth d, the path through which current flows is shortened, thereby reducing transmission loss of electrical signals. This is particularly suitable for a conductive member 110 that can be used for high-speed, high-capacity communications in the high-frequency range, such as 5G.

[0080] In this embodiment, the conductive particles 112a serving as the conductive medium have a small average particle size of 10 to 300 μm, which increases the surface area of ​​the conductive medium and therefore the area of ​​the conductive path, making it easier for current to flow and reducing transmission loss of electrical signals.

[0081] Furthermore, in this embodiment, the conductive member 110 is configured such that the fine conductive particles 112a are connected in a beaded pattern in the thickness direction of the conductive member 110, forming a large number of conductive paths. This increases the surface area for conducting the conductive medium, making it easier for current to flow through the conductive parts 112 of the conductive member 110, thereby reducing transmission loss of electrical signals. [Example]

[0082] Next, the conductive member according to one embodiment of the present invention will be described in detail with reference to examples, although the present embodiment is not limited to these examples.

[0083] In order to verify the effect of the conductive members 110 and 210 of this embodiment on the transmission loss of electrical signals, Examples 1 to 3 were prepared as samples of the conductive member 110, Examples 4 to 5 were prepared as samples of the conductive member 210, and Comparative Examples 1 to 3 were prepared as described below.

[0084] In Example 1, spherical nickel particles with silver-plated surfaces that met the following conditions were used as the conductive particles 112a of the conductive member 110 of this embodiment: Specifically, the particles used had an apparent density of 3.0 to 3.5 g / cm, an average particle size of 46.9 μm, a silver weight ratio of 10%, a silver plating thickness of 0.6 μm, a surface roughness Sa of 2.6 μm, a surface roughness Sdr of 9.6, and an aspect ratio of 1.5 to 4.0.

[0085] In Example 2, spherical nickel particles with silver-plated surfaces that met the following conditions were used as the conductive particles 112a of the conductive member 110 of this embodiment: Specifically, compared to Example 1, the average particle size was changed to 23.1 μm, the surface roughness Sa to 1.6 μm, and the surface roughness Sdr to 1.6.

[0086] In Example 3, spherical nickel particles with silver-plated surfaces that met the following conditions were used as the conductive particles 112a of the conductive member 110 of this embodiment. Specifically, compared to Example 1, the particles used were changed to have an apparent density of 3.0 to 4.0, an average particle size of 59.1 μm, a silver plating thickness of 0.8 μm, a surface roughness Sa of 3.9 μm, a surface roughness Sdr of 15.4, and an aspect ratio of 1.0 to 1.5.

[0087] In Example 4, graphite powder with an apparent density of 0.1 g / cm3, an average particle size of 10 μm, a surface roughness Sa of 0.8 μm, a surface roughness Sdr of 10.5, and an aspect ratio of 1000 was used as the conductive particles of the conductive member 210, which is a modified example of this embodiment.

[0088] In Example 5, flake silver particles with an apparent density of 1.8 g / cm3, an average particle size of 5.5 μm, a surface roughness Sa of 0.5 μm, and a surface roughness Sdr of 7.0 were used as the conductive particles for the conductive member 210, which is a modified example of this embodiment.

[0089] In Comparative Example 1, spike-shaped nickel powder with silver-plated surfaces was used, meeting the following conditions: apparent density of 1.6 to 2.6 g / cm3, average particle size of 22.7 μm, silver weight ratio of 10%, silver plating thickness of 0.8 μm, surface roughness Sa of 6.0 μm, surface roughness Sdr of 24.6, and aspect ratio of 1.0 to 1.5.

[0090] In Comparative Example 2, filament-shaped (chain-shaped) nickel powder with silver-plated surfaces was used, meeting the following conditions: apparent density of 0.5 to 0.65 g / cm3, average particle size of 49.4 μm, silver weight ratio of 10%, silver plating thickness of 0.8 μm, surface roughness Sa of 5.9 μm, and surface roughness Sdr of 41.4.

[0091] In Comparative Example 3, a metal leaf spring having a height of 1 mm and made of stainless steel having a thickness of 0.1 mm and a surface plated with gold to a thickness of 0.5 μm was used, which met the following conditions.

[0092] Then, using an Agilent Network Analyzer N5224A, the transmission loss of the electrical signals of each of Examples 1 to 5 and Comparative Examples 1 to 3 was measured. Specifically, a sample of each of Examples 1 to 5 and Comparative Examples 1 to 3 was sandwiched between two circuit boards, a signal was output from Port-1 of one of the circuit boards, and the signal strength was measured at Port-2 of the other circuit board. The measurement frequency was 0 to 30 GHz, and each sample was compressed from a thickness of 1 mm to 0.75 mm, and the signal strength was measured. In advance, as a measurement preparation, two coaxial cables extending from the measuring instrument were connected with a through jig to eliminate loss components of the circuit board jig. In addition, correction adjustments were made to eliminate noise (loss) from the circuit board jig and cable, and the loss of only the conductive members was measured.

[0093] The measurement results for each example and each comparative example are shown in the following Table 1. In Comparative Example 3, the column for silver plating thickness shows the gold plating thickness.

[0094] [Table 1]

[0095] As shown in Table 1 above, in each of Examples 1 to 5, in which the surface roughness represented by the arithmetic mean height (Sa) was 5 or less, the absolute value of the transmission loss was 4 dB or less. In contrast, in Comparative Examples 1 and 2, in which the surface roughness represented by the arithmetic mean height (Sa) was greater than 5, the absolute value of the transmission loss was also greater than 5. This shows that the transmission loss can be reduced by setting the surface roughness represented by the arithmetic mean height (Sa) of the surface of the conductive particles 112a to 5 or less.

[0096] Furthermore, in each of Examples 1 to 5, in which the surface roughness represented by the developed area ratio (Sdr) was 20 or less, the absolute value of the transmission loss was 4 dB or less. In contrast, in Comparative Examples 1 and 2, in which the surface roughness represented by the developed area ratio (Sdr) was greater than 20, the absolute value of the transmission loss was greater than 5. This demonstrates that the transmission loss can be reduced by setting the surface roughness represented by the developed area ratio (Sdr) of the surface of the conductive particles 112a to 20 or less.

[0097] Furthermore, Examples 1 to 5 had reduced transmission loss compared to Comparative Examples 1 to 3. In particular, Example 2, which had the smallest surface roughness Sa and Sdr, had the lowest transmission loss. This indicates that the smaller the surface roughness Sa and Sdr of the conductive particles 112a constituting the conductive member 110, the smaller the transmission loss.

[0098] Furthermore, when comparing the transmission loss of Examples 1 to 3 in which the conductive particles 112a were spherical nickel particles with silver-plated surfaces, the transmission loss of Example 2, which had the smallest average particle size, was the lowest. This shows that the smaller the particle size of the conductive particles 112a that make up the conductive member 110, the smaller the transmission loss.

[0099] Although the embodiments and examples of the present invention have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. Therefore, all such modifications are intended to be included within the scope of the present invention.

[0100] For example, a term described at least once in the specification or drawings together with a different term having a broader or equivalent meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations and operations of the conductive members, electrical connection members, and connection structures are not limited to those described in the embodiments and examples of the present invention, and various modifications are possible. [Explanation of symbols]

[0101] 10. Connection structure 12 First connection object 14 Second connection object 100 Electrical connection member 110, 210 Conductive member 112 Conductive part 112a Conductive particles (conductive medium) 112a1 magnetic particles 112a2 conductive metal layer 114 Insulation part (polymer matrix) 120 Fastening member 130 Connecting member 130a through hole 212 Conductive film (conductive medium) 214 Rubber body (polymer matrix)

Claims

1. A conductive member that electrically connects a first connection object and a second connection object, a polymer matrix made of a rubber-like elastomer; a conductive medium having conductivity, the conductive medium is made of conductive particles arranged continuously along the conduction direction of the conductive member, and the surface roughness of the conductive particles, expressed by an arithmetic mean height (Sa), is 5 μm or less; The surface roughness of the conductive particles, expressed as a developed area ratio (Sdr), is 20 or less. Conductive material.

2. The conductive particles have an average particle size of 10 to 300 μm. The conductive member according to claim 1 .

3. The conductive particles are formed by coating the surfaces of magnetic particles with a conductive metal layer, and are continuously arranged in the thickness direction of the conductive member and contained in the polymer matrix. The conductive member according to claim 1 or 2.

4. The thickness of the conductive metal layer is 0.1 to 4 μm. The conductive member according to claim 3 .

5. The specific surface area of ​​the magnetic particles is 10 to 800 cm ２ / g The conductive member according to claim 3 or 4.

6. the conductive particles are flake particles, The conductive medium is composed of a conductive coating containing the flake particles that coats the surface of the polymer matrix. The conductive member according to claim 1 or 2.

7. The flake particles are scale-shaped or fibrous in shape with an aspect ratio of 2 or more. The conductive member according to claim 6 .

8. The conductive member is a columnar conductive portion containing the conductive particles in a central region of the polymer matrix; an insulating portion provided in a region covering the outer peripheral surface side of the conductive portion, the insulating portion not containing the conductive particles in the polymer matrix, The conductive portion and the insulating portion are integrally formed. The conductive member according to any one of claims 1 to 7.

9. The conductive portion has an electrical resistance of 100 mΩ or less when compressed by 25%. The conductive member according to claim 8 .

10. The filling rate of the conductive particles in the conductive portion is 25 to 80 volume %. The conductive member according to claim 8 or 9.

11. An electrical connection member for electrically connecting a first connection object and a second connection object, The conductive member according to any one of claims 1 to 10, a fixing member that keeps the conductive member in a compressed state in the thickness direction of the conductive member while bringing the conductive member into contact with the first connection object and the second connection object. Electrical connection components.

12. the first connection object is a terminal provided on a glass surface, and the second connection object is a cable terminal or a terminal of a flexible substrate, The electrical connection member is configured to electrically connect the first connection object and the second connection object in a compressed state between them. The electrical connection member according to claim 11 .

13. The electrical connection member includes a plurality of the conductive members spaced apart from one another. The electrical connection member according to claim 11 or 12.

14. The fixing member is formed to surround the plurality of conductive members. The electrical connection member according to claim 13 .

15. In a connection structure configured by electrically connecting a first connection object and a second connection object with an electrical connection member, The conductive member according to any one of claims 1 to 10 is fixed in a compressed state between the first connection object and the second connection object, so that the electrical connection member electrically connects the first connection object and the second connection object. Connection structure.

16. The electrical connection member has a fixing member whose upper surface side is adhered to the first connection object and whose lower surface side is adhered to the second connection object. The connection structure according to claim 15.

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