Electrical connection structure, and connection body of insulated wire and printed wiring board

Abstract

To provide: an electrical connection structure in which the transmission loss in a connection part is reduced; an insulated wire; and a connection body of a printed wiring board.SOLUTION: An electrical connection structure according to an embodiment of the present disclosure is an electrical connection structure between: a plurality of conductors in an insulated wire having the plurality of conductors arranged at an interval and an insulation layer that covers circumferential surfaces of the plurality of conductors individually or collectively; and a plurality of wires on a printed wiring board having a substrate and the plurality of wires arranged at an interval on the substrate. The plurality of conductors are exposed respectively at tip regions in an extension direction of the plurality of conductors, the exposed tips are superimposed in one-to-one correspondence on the plurality of wires to form connection parts, respectively, on the substrate. The substrate has groove parts each formed between the connection parts that are adjacent to each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an electrical connection structure and a connection between an insulated wire and a printed wiring board. [Background technology]

[0002] When transmitting an electrical signal (hereinafter also referred to as "signal") to a printed wiring board or the like of an electronic device, an insulated wire such as a flexible flat cable (hereinafter also referred to as "FFC") may be used, and multiple conductors of this insulated wire may be electrically connected to multiple wirings of the printed wiring board.

[0003] When these insulated wires and printed wiring boards are connected via connectors, problems arise such as deterioration of noise resistance and reduction in impedance, so an electrical connection structure in which the insulated wires and printed wiring boards are directly connected has been proposed (see JP 2013-196938 A). In this electrical connection structure, a flat substrate is used as the substrate for the printed wiring board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-196938 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, when transmitting signals, transmission methods such as parallel transmission, serial transmission, and differential transmission are used, but among these, differential transmission is considered to be advantageous in terms of increasing communication speed.

[0006] However, in the electrical connection structure described in the above patent document, the differential impedance at the connection between the multiple conductors of the insulated wire and the multiple wirings of the printed wiring board is relatively lower than the differential impedance at the portion consisting of only the conductors and the portion consisting of only the wirings (such a decrease in differential impedance is also called "differential impedance mismatch"), and as a result, there is a risk of transmission loss occurring at the connection.

[0007] Therefore, an object of the present invention is to provide an electrical connection structure and a connection body of an insulated wire and a printed wiring board in which transmission loss at the connection portion is reduced. [Means for solving the problem]

[0008] An electrical connection structure according to one aspect of the present disclosure, which has been made to solve the above-mentioned problems, is an electrical connection structure between a plurality of conductors in an insulated wire having a plurality of conductors arranged at intervals from each other and an insulating layer that covers the peripheral surfaces of the plurality of conductors individually or collectively, and a plurality of wirings in a printed wiring board having a substrate and a plurality of wirings arranged at intervals on the substrate, wherein the plurality of conductors are exposed at tip regions in the extension direction of the plurality of conductors, and the exposed tip portions are superimposed on the plurality of wirings in a one-to-one correspondence to form connection portions on the substrate, and the substrate has groove portions formed between adjacent connection portions.

[0009] A connection body of an insulated wire and a printed wiring board according to another aspect of the present disclosure, which has been made to solve the above-mentioned problems, includes the above-mentioned electrical connection structure. [Effects of the Invention]

[0010] The electrical connection structure and the connection body of the insulated wire and the printed wiring board according to the present disclosure have reduced transmission loss at the connection portion. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic plan view showing an electrical connection structure in a connection body of an insulated wire and a printed wiring board according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] 3 is an end view taken along the arrow BB in FIG. 2. FIG. [Figure 4] FIG. 4 is a schematic end view similar to FIG. 3, showing an electrical connection structure in a connection body of an insulated wire and a printed wiring board according to the second embodiment. [Figure 5] FIG. 5 is a schematic end view similar to FIG. 3, showing an electrical connection structure in a connection body of an insulated wire and a printed wiring board according to the third embodiment. [Figure 6] FIG. 6 is a schematic end view similar to FIG. 3, showing an electrical connection structure in a connection body of an insulated wire and a printed wiring board according to a fourth embodiment. [Figure 7] FIG. 7 is a schematic end view showing the electrical connection structure of Comparative Example 1, similar to FIG. [Figure 8] FIG. 8 is a graph showing the simulation results of the change in differential impedance in the connection bodies of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Description of the embodiments of the present disclosure] In order to solve the above problem, the inventors of the present invention have conducted extensive research and have found the following: In general, the characteristic impedance Z0 of a microstrip line is approximated as in the following equation (1), and the differential impedance Z diff is expressed as the following formula (2). Z0={60 / (0.475ε r +0.67) (1 / 2)}×ln{4h / 0.67(0.8W+t)}···(1) Z diff =2Z0{1-0.48e (-0.96×(S / h))}···(2) In the above formula (1), ε ris the relative permittivity of the substrate, h is the distance between the ground plane and the conductor, W is the conductor width, and t is the conductor thickness. In the above formula (2), S is the distance between the conductors, and h is the distance between the ground layer and the conductor.

[0013] Here, from the above formulas (1) and (2), it is necessary to increase both S and h as a means of suppressing the decrease in differential impedance at the connection between the conductor and the wiring (i.e., increasing the differential impedance). However, increasing S and h leads to an increase in the size of the electrical connection structure. Therefore, the inventors have considered that reducing the effective dielectric constant of the wiring is an effective way to increase the differential impedance at the connection.

[0014] Furthermore, in general, the greater the relative dielectric constant of the surrounding area of ​​a wiring, the greater the effective dielectric constant of the wiring. Conversely, the smaller the relative dielectric constant of the surrounding area, the smaller the dielectric constant of the wiring. Thus, the effective dielectric constant of a wiring depends on the relative dielectric constant of the surrounding area. Taking this into consideration, the inventors of the present invention have concluded that in order to reduce the effective dielectric constant of a connection, it is effective to reduce the relative dielectric constant of the surrounding area of ​​a connection.

[0015] Furthermore, the inventors focused on the substrate present around the connection parts of the conductors and wiring, and also noticed that the relative dielectric constant of air (=1) is smaller than the relative dielectric constant of the substrate (material of which it is made). With this in mind, the inventors discovered that by providing a groove between the connection parts in the substrate, part of the substrate among the components around the connection parts can be replaced with air (i.e., an air layer) or a material with a smaller relative dielectric constant than the substrate (hereinafter also referred to as an "air layer, etc."), thereby making it possible to reduce the effective dielectric constant of the connection parts.

[0016] In this way, the inventors discovered that by providing a groove in the substrate, the differential impedance at the connection can be increased, thereby reducing transmission loss at the connection, and thus completed the present invention.

[0017] That is, an electrical connection structure according to one aspect of the present disclosure is an electrical connection structure between a plurality of conductors in an insulated wire having a plurality of conductors arranged at intervals from each other and an insulating layer covering the peripheral surfaces of the plurality of conductors individually or collectively, and a plurality of wirings in a printed wiring board having a substrate and a plurality of wirings arranged at intervals on the substrate, wherein the plurality of conductors are exposed at the tip regions in the extension direction of the plurality of conductors, and the exposed tip regions are superimposed on the plurality of wirings in a one-to-one correspondence to form connection portions on the substrate, and the substrate has groove portions formed between adjacent connection portions.

[0018] In this electrical connection structure, the grooves are formed between the connection portions of the substrate, and as a result, a portion of the substrate is replaced by an air layer or the like in the grooves, making the relative dielectric constant around the connection portions relatively small, and as a result, the differential impedance at the connection portions is relatively large. Therefore, the electrical connection structure reduces transmission loss at the connection portions.

[0019] The ratio of the average width of the opening of the trench located between the adjacent wirings in a direction perpendicular to the extending direction to the average spacing between the adjacent wirings may be 50% or more and 100% or less.

[0020] By setting the average width of the groove openings relative to the average spacing of the wiring within the above range, a portion of the substrate can be more reliably replaced with an air layer or the like, thereby more reliably increasing the differential impedance at the connection portion, and therefore more reliably reducing transmission loss at the connection portion.

[0021] A ratio of an average length in the extension direction of the opening of the groove to an average length in the extension direction of the connecting portion may be 90% or more and 110% or less.

[0022] By setting the ratio of the average length of the groove openings to the average length of the connection portions within the above range, a portion of the substrate can be replaced with an air layer or the like over a length that is approximately equivalent to the average length of the connection portions, thereby more reliably increasing the differential impedance at the connection portions and therefore more reliably reducing transmission loss at the connection portions.

[0023] The average depth of the groove may be equal to or greater than the average thickness of the wiring.

[0024] By making the average depth of the groove equal to or greater than the average thickness of the wiring, at least a portion of the substrate is replaced with an air layer or the like by an amount corresponding to the thickness of the wiring in the connection portion located closest to the substrate, thereby more reliably increasing the differential impedance at the connection portion and therefore more reliably reducing transmission loss at the connection portion.

[0025] The connection portion may have a solder portion that bonds the tip end of the conductor to the wiring.

[0026] By bonding the tip end of the conductor and the wiring with the solder, the tip end of the conductor and the wiring are more reliably connected.

[0027] The electrical connection structure may further include a resin layer covering the connection portion. The resin layer is preferably made of an insulating resin material having a lower dielectric constant than the substrate.

[0028] By providing the electrical connection structure with the resin layer, it is possible to increase the differential impedance at the connection portion and improve the insulation of the connection portion against the external environment.

[0029] The resin layer may have recesses between the adjacent connection portions that partition the resin layer, and an average minimum thickness of the recesses from the substrate may be smaller than an average thickness of the connection portions.

[0030] The formation of the recess in the resin layer makes it possible to increase the differential impedance at the connection portion compared to when the resin layer does not have the recess, thereby improving the insulation properties of the connection portion and more reliably reducing the transmission loss at the connection portion.

[0031] A connection body between an insulated wire and a printed wiring board according to another aspect of the present disclosure includes the above-described electrical connection structure.

[0032] Since the connector has the above-described electrical connection structure, transmission loss at the connection portion is reduced.

[0033] Here, "the direction of extension of the conductor" refers to the direction of current flow in the conductor, and this "direction of extension of the conductor" corresponds to the longitudinal direction of the conductor. "The ratio of the average width of the groove portion located between adjacent wirings to the average spacing between the adjacent wirings" refers to the ratio of the average width of the groove portion to the average spacing between the wirings in which the groove portion is formed, when a groove portion is formed between adjacent wirings. "The resin layer has recesses that partition the resin layer between adjacent connection portions, and the average minimum thickness of the recesses from the substrate is smaller than the average thickness of the connection portions" also includes a state in which the multiple partitions of the resin layer are separated from each other, specifically a state in which there is no resin layer between the connection portions; in other words, it also includes a case in which the thickness (and average minimum thickness) of the recesses is zero.

[0034] [Details of the embodiments of the present disclosure] Hereinafter, embodiments of an electrical connection structure and a connection body of an insulated wire and a printed wiring board according to the present disclosure will be described in detail with reference to the drawings.

[0035] [First embodiment] [Electrical connection structure and connector] As shown in FIGS. 1 to 3, the electrical connection structure of this embodiment is a structure of a connection portion 20 of a connector between an insulated electric wire 1 and a printed wiring board 10, and the insulated electric wire 1 is disposed on the printed wiring board 10.

[0036] The electrical connection structure of this embodiment is an electrical connection structure between a plurality of conductors 4 in an insulated wire 1 having an insulating layer 7 that covers the peripheral surfaces of the plurality of conductors 4 individually or collectively (covering them collectively in Figure 1), and a plurality of wirings 12 in a printed wiring board 10 that has a substrate 11 and a plurality of wirings 12 that are arranged at intervals on the substrate 11.

[0037] The conductors 4 are arranged in an exposed state from the end of the insulating layer 7 toward the tip ends of the wirings 12. The tip ends of the conductors 4 are overlapped in a one-to-one correspondence with the tip ends of the wirings 12 to form electrical connection portions 20. The substrate 11 has grooves 13 formed between the connection portions 20 adjacent to each other.

[0038] <Insulated wire> The insulated wire 1 has a plurality of conductors 4 arranged side by side with a gap between them. More specifically, the plurality of conductors 4 are arranged substantially parallel to one another in the same plane. "Substantially parallel" means that the angle between the central axes is within ±10°.

[0039] In the embodiment shown in Fig. 1, the insulated wire 1 has a plurality of conductors 4 and an insulating layer 7 that collectively covers the circumferential surfaces of the plurality of conductors 4. The number of the plurality of conductors 4 is not particularly limited. Although Fig. 1 shows an embodiment in which the plurality of conductors 4 are arranged at equal intervals, this interval can be set appropriately depending on the intervals between the plurality of wirings 12 on the printed wiring board 10, design specifications, etc., and the plurality of conductors 4 do not need to be arranged at equal intervals.

[0040] As described above, in this embodiment, the insulated wire is an insulated wire 1 that is a flexible flat cable (FFC) having a plurality of conductors 4 and an insulating layer 7 that collectively covers the circumferential surfaces of the plurality of conductors, as shown in Fig. 1. However, the insulated wire may also be an insulated wire that includes a plurality of conductors and a covering layer that covers each of the circumferential surfaces of the plurality of conductors.

[0041] (conductor) The conductor 4 is not particularly limited, and may be, for example, a metal wire such as copper, copper alloy, aluminum, or aluminum alloy. Such metal wire may be a solid wire or a twisted wire. In the case of a twisted wire, the number of strands is not particularly limited, but may be, for example, 2 to 30.

[0042] The cross-sectional shape of the metal wire forming the conductor 4 is not particularly limited, and various shapes such as a circle, a square, or a rectangle can be adopted.

[0043] The lower limit of the average thickness of the conductor 4 (average diameter when the cross section is circular) is preferably 10 μm, more preferably 15 μm. On the other hand, the upper limit of the average thickness is preferably 500 μm, more preferably 400 μm. If the average thickness is less than the lower limit, the conductor 4 may be prone to breakage. On the other hand, if the average thickness of the conductor 4 exceeds the upper limit, the electrical connection structure may be unnecessarily large. The average thicknesses of multiple conductors 4 may be the same or different. Note that the "average thickness" is the average value of thicknesses measured at any five points in the extension direction (longitudinal direction) of the conductor 4. Hereinafter, "average thickness" has the same meaning.

[0044] The lower limit of the average width (average diameter when the cross section is circular) of the conductor 4 in the direction perpendicular to the extension direction (hereinafter also referred to as the "width direction") is preferably 10 μm, more preferably 15 μm. On the other hand, the upper limit of the average width is preferably 500 μm, more preferably 400 μm. If the average width is less than the lower limit, the conductor 4 may be prone to breakage. On the other hand, if the average width of the conductor 4 exceeds the upper limit, the electrical connection structure may be unnecessarily large. The average widths of multiple conductors 4 may be the same or different. The "average width" is the average value of widths measured at any five points in the extension direction (longitudinal direction) of the conductor 4. Hereinafter, "average width" has the same meaning.

[0045] The average exposed length of the conductor 4 from the insulating layer 7 is, for example, 0.2 mm or more and 5.0 mm or less. The "average exposed length" of the conductor 4 is the average value of the lengths in the extension direction measured at any five points in the width direction of the exposed portion (tip end) of the conductor 4.

[0046] The average spacing between adjacent conductors 4 can be set appropriately depending on the average spacing S of the wirings 12, which will be described later.

[0047] In the embodiment shown in FIG. 1, each conductor 4 exposed from the insulating layer 7 is connected to each wiring 12 by a solder portion 21, which will be described later.

[0048] In this embodiment, the printed wiring board 10 has a plurality of signal lines as the plurality of wirings 12, but it may also have a plurality of signal lines and a plurality of ground lines as the plurality of wirings 12. For example, it may have a plurality of (e.g., four) wirings, and of these plurality of wirings, the two outermost wirings are ground lines and the remaining inner wirings (e.g., two wirings) are signal lines.

[0049] (insulating layer) The insulating layer 7 is laminated on the peripheral surface of the conductor 4 so as to cover the conductor 4. The insulating layer 7 may have a single layer structure or a multi-layer structure of two or more layers.

[0050] As described above, the insulated wire 1 of the present embodiment shows an embodiment in which the circumferential surfaces of the plurality of conductors 4 are collectively covered with the insulating layer 7. However, the insulated wire may also have an embodiment in which the circumferential surfaces of the plurality of conductors 4 are individually covered with the insulating layer 7. That is, the circumferential surfaces of the plurality of conductors 4 may each be covered with the insulating layer 7.

[0051] The material of the insulating layer 7 is not particularly limited as long as it has insulating properties and flexibility, and examples that can be used include ethylene resins such as polyethylene, ethylene vinyl acetate copolymer, and ethylene ethyl acrylate copolymer; resins obtained by blending ethylene resin with polyolefins such as polypropylene, ethylene propylene rubber, and styrene elastomer; polyester resins such as PET (polyethylene terephthalate); polyimide, polyamideimide, polyesterimide, silane crosslinkable resin compositions; and fluororesins such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), and FEP (perfluoroethylenepropene copolymer).

[0052] The insulating layer 7 can be coated on the conductors 4 by, for example, extruding molten resin onto the surfaces of multiple conductors 4 and hardening it, or by applying a paint made by dissolving resin in an organic solvent to the surfaces of the conductors 4 and baking it.

[0053] The average thickness (wall thickness) of the insulating layer 7 is not particularly limited, but can be, for example, 3 μm or more and 1 mm or less.

[0054] The insulating layer 7 may have a primer layer in contact with the conductor 4. This primer layer can be preferably made of a cured crosslinkable resin such as ethylene that does not contain metal hydroxide. By providing such a primer layer, it is possible to prevent deterioration over time in the peelability between the insulating layer 7 and the conductor 4.

[0055] <Printed wiring board> 1, printed wiring board 10 has an insulating substrate 11 and a plurality of wirings 12 formed as a plurality of layers laminated on the surface of substrate 11. A plurality of conductors 4 of insulated wire 1 are superimposed on these plurality of wirings 12 in a one-to-one correspondence to form connection portion 20.

[0056] (substrate) The substrate 11 of the printed wiring board 10 is made of an insulating plate-like material. The plate-like material constituting the substrate 11 may be a rigid substrate or a flexible substrate. Specifically, a resin plate can be used as the rigid substrate. Suitable materials for the resin plate include, for example, a substrate made of glass cloth impregnated with epoxy resin (glass epoxy) and a substrate made of glass cloth impregnated with polyphenylene ether (PPE). Specifically, a resin film can be used as the flexible substrate. Suitable materials for the resin film include, for example, polyimide, polyethylene terephthalate, and PPE. The substrate 11 may contain fillers, additives, and the like. The dielectric constant of the substrate 11 is typically about 3 to 5. For example, the dielectric constant of the glass epoxy is about 4 to 5, and the dielectric constant of the PPE is about 3 to 4.

[0057] The average thickness of the substrate 11 is set appropriately depending on the design concept, etc. For example, if the average thickness of the substrate 11 is too small, the strength of the substrate 11 may be insufficient. On the other hand, if the average thickness of the substrate 11 is too large, the electrical connection structure may be unnecessarily thick. Therefore, for example, these points can be taken into consideration along with the design concept, and the average thickness of the substrate 11 can be set appropriately. The average thickness of the substrate 11 can be set to a level that allows the substrate 11 to perform its function even when groove portions 13, which will be described later, are formed.

[0058] (groove) The substrate 11 has grooves 13 formed between adjacent connection portions 20 (i.e., between the wirings 12). In this embodiment, the grooves 13 are formed between adjacent wirings 12 on the substrate 11 so as to extend in the above-mentioned direction.

[0059] The average width W1 of the openings of the grooves 13 in a direction perpendicular to the extension direction (width direction) can be appropriately set depending on the degree of increase in differential impedance at the connection portion 20. For example, the larger the average width W1 of the openings of the grooves 13 located between the wires 12 relative to the average spacing S between the wires 12, the more the material forming the plate-like substrate 11 is replaced with an air layer, which tends to increase the differential impedance at the connection portion 20. In consideration of this point, the lower limit of the ratio of the average width W1 of the openings of the grooves 13 located between the adjacent wires 12 to the average spacing S between the adjacent wires 12 (hereinafter also referred to as the "first ratio") is preferably 50%, more preferably 60%, even more preferably 70%, and particularly preferably 80%. On the other hand, in consideration of manufacturability and the like, the upper limit of the first ratio is preferably 100% (see FIGS. 1 and 3), more preferably 90%. The average width W1 of the opening of the groove 13 can be set in accordance with the average interval S between the wirings 12, and can be set to, for example, 50 μm or more and 500 μm or less.

[0060] The average length L2 of the grooves 13 in the extension direction can be set as appropriate depending on the degree of increase in differential impedance at the connection parts 20, but from the perspective of appropriate impedance control, it is preferable that the average length L2 of the grooves 13 in the extension direction is equal to the average length L1 of the connection parts 20 in the extension direction. The "average length in the extension direction" refers to the average value of the lengths in the extension direction measured at any five points in the width direction. Hereinafter, the terms "average length in the extension direction" have the same meaning.

[0061] More specifically, the lower limit of the length L2 of the groove 13 in the extension direction is preferably 0.2 mm, more preferably 0.5 mm, while the upper limit of the length L2 of the groove 13 in the extension direction is preferably 4.5 mm, more preferably 4.0 mm.

[0062] The average depth D of the grooves 13 can be appropriately set depending on the degree to which the differential impedance at the connection portion 20 can be increased. For example, a larger average depth D of the grooves 13 is preferable because a larger amount of the substrate 11 is replaced with an air layer, resulting in a larger differential impedance at the connection portion 20. In consideration of this, the average depth D of the grooves 13 is preferably equal to or greater than the average thickness T1 of the wiring 12. Specifically, the lower limit of the ratio of the average depth D of the grooves 13 to the average thickness T1 of the wiring 12 (hereinafter also referred to as the "third ratio") is preferably 100%, more preferably 105%. When the average depth D of the grooves 13 is equal to or greater than the average thickness T1 of the wiring 12, at least a portion of the substrate 11 is replaced with an air layer by an amount corresponding to the thickness of the wiring 12 located closest to the substrate 11 in the connection portion 20, thereby more reliably increasing the differential impedance at the connection portion 20. This more reliably reduces the transmission loss at the connection portion 20 in the electrical connection structure.

[0063] On the other hand, if the average depth D of the grooves 13 becomes too large, the strength of the substrate 11 may decrease, and the increase in differential impedance at the connection portions 20 may reach equilibrium, resulting in waste. Considering these points, the average depth D of the grooves 13 is preferably equal to or less than the average thickness T2 of the connection portions 20. Specifically, the upper limit of the ratio of the depth D of the grooves 13 to the average thickness T2 of the connection portions 20 (see FIG. 5) (hereinafter also referred to as the "fourth ratio") is preferably 100%, more preferably 90%. The "average depth" refers to the average value of depths measured at any five points in the extension direction (the depth from the outer surface of the substrate 11 to the deepest part of the grooves 13).

[0064] The cross-sectional shape of groove 13 is not particularly limited and can be set appropriately depending on the degree of increase in differential impedance at connection 20. For example, as shown in FIG. 2, the cross section of groove 13 may be a trapezoidal shape tapering toward the inside of substrate 11 (tapered shape), or may be a square, rectangular, semicircular, semi-elliptical, or other shape. The average width of the bottom side of groove 13 can be set appropriately to a degree that is, for example, equal to or less than the average width W1 of the opening of groove 13 and that can increase the differential impedance at connection 20.

[0065] In this embodiment, the groove portion 13 is formed only between the wirings 12 (i.e., between the connection portions 20), but it is also possible to adopt a configuration in which the groove portion 13 is formed further outside the wirings 12 located at both ends in the width direction.

[0066] (wiring) The plurality of wirings 12 (more specifically, the tips of the plurality of wirings 12) are arranged side by side on the substrate 11 with a gap between them. Specifically, the plurality of wirings 12 are arranged substantially parallel to one another on the substrate 11. These wirings 12 are formed into a desired planar shape (pattern) by, for example, etching a metal layer stacked on the surface of the substrate 11. The plurality of wirings 12 are each formed into a rectangular shape in a plan view and are arranged substantially parallel to one another.

[0067] Each of the wires 12 can be made of a conductive material, but is generally made of copper, for example. The surface of the wires 12 may also be plated. For example, the wires 12 may be covered with a pre-soldering portion (not shown). As the plating, tin plating, gold plating, or solder plating is preferred.

[0068] The lower limit of the average thickness T1 of the wiring 12 is preferably 8 μm, more preferably 15 μm. The upper limit of the average thickness T1 of the wiring 12 is preferably 100 μm, more preferably 70 μm. If the average thickness T1 of the wiring 12 is less than the lower limit, the electrical conductivity may be insufficient. On the other hand, if the average thickness T1 of the wiring 12 exceeds the upper limit, the electrical connection structure may become unnecessarily thick.

[0069] The lower limit of the average width of the wiring 12 is preferably 0.8 times, and more preferably 1 time, the average width of the conductor 4 of the insulated wire 1. The upper limit of the average width of the wiring 12 is preferably 5 times, more preferably 3 times, and more preferably 2 times the average width of the conductor 4. If the average width of the wiring 12 is less than the lower limit, it may not be easy to connect the conductor 4. On the other hand, if the average width of the wiring 12 exceeds the upper limit, the width of the electrical connection structure may be unnecessarily large.

[0070] More specifically, the lower limit of the average width of the wiring 12 is preferably 50 μm, more preferably 75 μm, while the upper limit of the average width of the wiring 12 is preferably 800 μm, more preferably 600 μm.

[0071] The average spacing S between adjacent wirings 12 can be, for example, 0.5 to 5 times the average diameter of the conductor 4. The average spacing S between wirings 12 means the average value of spacings measured at any five points in the extension direction.

[0072] More specifically, the lower limit of the average spacing S between adjacent wirings 12 is preferably 50 μm, and more preferably 75 μm. On the other hand, the upper limit of the average spacing S between adjacent wirings 12 is 500 μm is preferred, and 400 μm is more preferred.

[0073] The average spacing S between adjacent wirings may be the same (equidistant) or may be different.

[0074] <Connection> The connection part 20 is formed by connecting the tip of the conductor 4 to the wiring 12. In the embodiment shown in FIG. 1 , the connection part 20 has a solder part 21 that bonds the tip of the conductor 4 to the wiring 12. By bonding the tip of the conductor 4 to the wiring 12 with the solder part 21, the tip of the conductor 4 and the wiring 12 are more reliably connected. Note that the method of connecting the tip of the conductor 4 to the wiring 12 is not particularly limited to bonding with a solder part.

[0075] The solder that constitutes the solder portion 21 is not particularly limited, but for example, lead-free solder such as an SnAgCu alloy, an SnZnBi alloy, an SnCu alloy, or an SnAgInBi alloy can be used.

[0076] The average thickness T2 of the connection portion 20 is the sum of the average thickness of the conductor 4 and the average thickness T1 of the wiring 12. Considering the average thickness of the conductor and the average thickness T1 of the wiring 12, the lower limit of the average thickness T2 of the connection portion 20 is preferably 50 μm, more preferably 90 μm. On the other hand, the upper limit of the average thickness T2 of the connection portion 20 is preferably 600 μm, more preferably 500 μm.

[0077] [Method for manufacturing electrical connection structure] Next, a method for manufacturing the electrical connection structure between the insulated wire 1 and the printed wiring board 10 in this embodiment, that is, the connection between the insulated wire 1 and the printed wiring board 10, will be described.

[0078] The method for manufacturing an electrical connection structure of this embodiment includes the steps of preparing an insulated wire 1, preparing a printed wiring board 10, and connecting the multiple conductors 4 of the insulated wire 1 to the multiple wirings 12 of the printed wiring board 10. The step of preparing the insulated wire 1 can be performed using a known method to produce the insulated wire 1. The step of preparing the printed wiring board 10 includes the steps of stacking the multiple wirings 12 on a substrate 11 by a known method (stacking step), and forming the multiple grooves 13 so as to be positioned between the multiple wirings 12 on the substrate 11 (forming step). The order in which the stacking step and the forming step are performed is not particularly limited.

[0079] In the forming step, a cutting device such as a cutter having a known circular blade may be used to cut the material forming the flat plate-like substrate 11. For example, the average width of the grooves 13 can be adjusted by changing the thickness of the circular blade. For example, the length of the grooves 13 in the extension direction can be adjusted by adjusting the movement distance of the circular blade. For example, the average depth of the grooves 13 can be adjusted by adjusting the depth to which the circular blade penetrates into the material. Furthermore, the outer shape can be processed using a laser such as a UV-YAG laser or a CO2 laser.

[0080] The process of connecting the multiple conductors 4 of the insulated wire 1 to the multiple wirings 12 of the printed wiring board 10 can be carried out using a known method, for example, by overlapping the tip ends of the multiple conductors 4 with the multiple wirings 12 and bonding them together with solder parts 21.

[0081] (advantage) In the electrical connection structure and the connection of the insulated wire and the printed wiring board of this embodiment, the transmission loss at the connection portion 20 is reduced.

[0082] In addition, since the grooves 13 are formed in the substrate 11, the projected distance is increased accordingly, and therefore the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment have improved insulation between the connection parts 20. Furthermore, since the grooves 13 are formed in the substrate 11, the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment are made lighter in weight.

[0083] [Second embodiment] [Electrical connection structure and connector] In the electrical connection structure and connection body of this embodiment, the connection portion 20 of the first embodiment is covered with a resin layer 30. More specifically, the connection portion 20 is covered with the resin layer 30 together with the substrate 11 and the groove portion 13. Other than that, the electrical connection structure and connection body have exactly the same configuration as the first embodiment. Therefore, only the configuration different from the first embodiment will be described for this embodiment. Furthermore, the same members as those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0084] <Resin layer> As shown in Fig. 4, in this embodiment, the connection portions 20, the substrate 11, and the groove portions 13 are covered with a resin layer 30. Specifically, the resin layer 30 is formed on the substrate 11 so as to cover the connection portions 20 and the groove portions 13. In this embodiment, the resin layer 30 is formed to extend in the width direction (the left-right direction in Fig. 4) so ​​as to cover the entirety of the multiple connection portions 20. In this embodiment, a portion of the resin layer 30 is embedded in the groove portions 13, and the outer surface of the resin layer 30 (the surface on the side opposite to the substrate 11) is formed flat.

[0085] The relative dielectric constant of the resin layer 30 is preferably smaller than that of the substrate 11. Here, the relative dielectric constant of a resin is usually larger than that of an air layer. For this reason, if the resin of the resin layer 30 is embedded in the groove 13, there is a risk that the differential impedance at the connection portion 20 will be smaller than if the resin layer 30 is not embedded in the groove 13. However, by embedding the resin layer 30, which has a relative dielectric constant smaller than that of the substrate 11, in the groove 13, the differential impedance at the connection portion 20 can be made larger than if the groove 13 is not formed in the substrate 11.

[0086] For example, the dielectric constant of the resin layer 30 is preferably 2 or more and 3 or less, and can be appropriately set within this range so that the dielectric constant of the resin layer 30 is smaller than the dielectric constant of the substrate 11. Examples of materials for such resin layer 30 include ultraviolet (UV) curable resins. Examples of UV curable resins include acrylic resins and bismaleimide resins.

[0087] The average thickness (average maximum height) of the resin layer 30 from the substrate 11 can be appropriately set to be larger than the average thickness of the connection portion 20 .

[0088] Specifically, the lower limit of the average thickness (average maximum height) of the resin layer 30 is preferably 60 μm, more preferably 100 μm. If the average thickness of the resin layer 30 is less than the lower limit, the insulating properties may be reduced. On the other hand, the upper limit of the average thickness of the resin layer 30 is preferably 700 μm, more preferably 600 μm. If the average thickness of the resin layer 30 exceeds the upper limit, the resin layer 30 may be unnecessarily thick compared to its insulating properties.

[0089] The average length of the resin layer 30 in the extension direction can be appropriately set depending on the insulating performance of the connection portion 20, etc. For example, the smaller the average length of the resin layer 30 in the extension direction relative to the average exposed length of the conductor 4 from the insulating layer 7, the more likely the insulating performance will be reduced. On the other hand, the larger the average length L2 of the resin layer 30 in the extension direction relative to the average exposed length of the conductor 4 from the insulating layer 7, the more likely the resin layer 30 will be unnecessarily large. Specifically, the ratio of the average length of the resin layer 30 in the extension direction to the average exposed length of the conductor 4 from the insulating layer 7 (hereinafter also referred to as the "fifth ratio") is preferably 100% or more and 300% or less, and more preferably 105% or more and 200% or less. When the fifth ratio satisfies the above range, the insulating performance of the resin layer 30 can be more reliably exhibited.

[0090] More specifically, the lower limit of the length of the resin layer 30 in the extending direction is preferably 0.2 mm, more preferably 0.5 mm, while the upper limit of the length of the resin layer 30 in the extending direction is preferably 10 mm, more preferably 7 mm.

[0091] The cross-sectional shape of the resin layer 30 is not particularly limited and can be set appropriately.

[0092] [Method for manufacturing electrical connection structure] The method for manufacturing the electrical connection structure of this embodiment further includes a step of forming a resin layer 30 that covers the connection portion 20 after the step of connecting the multiple conductors 4 of the insulated wire 1 in the first embodiment described above to the multiple wirings 12 of the printed wiring board 10.

[0093] A known method can be used for the step of forming the resin layer 30. For example, the resin layer 30 can be formed by pouring a resin material using a dispenser and curing it by irradiating it with UV light.

[0094] In this embodiment, the resin layer 30 is embedded in the groove 13, but the connection portion 20 and the groove 13 may be covered with the resin layer 30 without being embedded in the groove 13. In this embodiment, the resin layer 30 is embedded in the connection portion 20, the groove 13, and a portion of the substrate 11, but the substrate 11 may not be covered with the resin layer 30. In this embodiment, the resin layer 30 has a flat outer surface, but the outer surface shape (cross-sectional shape) of the resin layer 30 is not particularly limited.

[0095] (advantage) In the electrical connection structure and the connection of the insulated wire and the printed wiring board of this embodiment, the transmission loss at the connection portion 20 is reduced.

[0096] In addition, since the grooves 13 are formed in the substrate 11, the projected distance is increased accordingly, and therefore the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment have improved insulation between the connection parts 20. Furthermore, since the grooves 13 are formed in the substrate 11, the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment are made lighter in weight.

[0097] Furthermore, the electrical connection structure of this embodiment, and the connection body of the insulated wire and the printed wiring board, are provided with a resin layer 30, which suppresses a decrease in differential impedance at the connection portion 20 while improving the insulation of the connection portion 20 against the external environment.

[0098] [Third embodiment] [Electrical connection structure and connector] The electrical connection structure and connector of this embodiment includes a resin layer 32 made of the same material as the resin layer 30 of the second embodiment, and a recess 32a is formed on the outer surface of the resin layer 32. Other than that, the electrical connection structure and connector of this embodiment have the same configuration as the electrical connection structure and connector of the second embodiment. Therefore, only the configuration that differs from the second embodiment will be described. Furthermore, the same components as those of the second embodiment are designated by the same reference numerals, and a description thereof will be omitted.

[0099] <Resin layer> As shown in FIG. 5, in this embodiment, similar to the second embodiment described above, the connection portions 20, the substrate 11, and the groove portions 13 are covered with a resin layer 32. Specifically, the resin layer 32 is formed on the substrate 11 so as to cover the connection portions 20 and the groove portions 13, and a portion of the resin layer 32 is embedded in the groove portions 13. In this embodiment, similar to the second embodiment described above, the resin layer 32 is formed so as to extend in the width direction (the left-right direction in FIG. 5) so as to cover the entirety of the plurality of connection portions 20. Meanwhile, in this embodiment, the resin layer 32 has recesses 32a that partition the resin layer 32 between adjacent connection portions 20. In this embodiment, the recesses 32a are formed so that the resin layer 30 is recessed toward the substrate 11.

[0100] The average maximum thickness (average height from the substrate 11) of the resin layer 32 located directly above the connection portion 20 from the substrate 11 can be set as appropriate to be larger than the average thickness T2 of the connection portion 20. The average maximum thickness of the resin layer 32 can be set similarly to the average thickness of the resin layer 30 of the second embodiment described above.

[0101] The average length of the resin layer 32 in the extending direction can be set in the same manner as the average length of the resin layer 30 in the extending direction of the second embodiment described above.

[0102] The recesses 32a are formed such that their average minimum thickness T3 from the substrate 11 (the average value of the shortest distance from the substrate 11 to the recesses 32a, i.e., the average distance from the substrate 11 to the deepest part of the recesses 32a) is smaller than the average thickness T2 of the connection portions 20. Specifically, the ratio of the average minimum thickness T3 of the recesses 32a from the substrate 11 to the average thickness T2 of the connection portions 20 (hereinafter also referred to as the "sixth ratio") is less than 100%. By forming such recesses 32a, a part of the resin layer 32 is replaced with an air layer by the recesses 32a, and the differential impedance at the connection portions 20 can be made larger than when the resin layer 32 does not have the recesses 32a. The smaller the sixth ratio, the better. From this point of view, the sixth ratio may be substantially 0, or may be 0 as shown in a fourth embodiment described later. By making the average minimum thickness T3 of the recesses 32a substantially zero, almost all of the resin layer 32 between the connection portions 20 is replaced with an air layer, which more reliably increases the differential impedance at the connection portions 20. Therefore, the transmission loss at the connection portions 20 can be more reliably reduced.

[0103] More specifically, when the average minimum thickness T3 of the recesses 32a exceeds 0, the upper limit of the average minimum thickness T3 of the recesses 32a is preferably 500 μm, and more preferably 400 μm.

[0104] The average width W2 of the portion of the recess 32a that is smaller than the average thickness of the connection portion 20 (hereinafter also referred to as the "first portion") can be appropriately set depending on the degree of increase in differential impedance at the connection portion 20, etc. For example, the larger the average width W2 of the first portion of the recess 32a, the larger the differential impedance at the connection portion 20 can be. In consideration of this, for example, the lower limit of the ratio of the average width W2 of the first portion of the recess 32a located between adjacent wirings 12 to the average spacing S between the adjacent wirings 12 (hereinafter also referred to as the "seventh ratio") is preferably 20%, more preferably 25%, and even more preferably 30%. When the lower limit satisfies the above range, the differential impedance at the connection portion 20 can be more reliably increased. Therefore, the transmission loss at the connection portion 20 in the electrical connection structure can be more reliably reduced. On the other hand, the upper limit of the seventh ratio may be 100% or 90%.

[0105] More specifically, the lower limit of the average width W2 of the first portion of the recess 32a is preferably 10 μm, more preferably 15 μm, while the upper limit of the average width W2 of the first portion of the recess 32a is preferably 500 μm, more preferably 400 μm.

[0106] The average length of the recesses 32a in the extension direction may be set to the same value as the average length of the resin layer 32 in the extension direction (i.e., the average length of the resin layer 30 in the extension direction of the second embodiment). Specifically, the average length of the recesses 32a in the extension direction may be set appropriately depending on the degree of increase in differential impedance at the connection portion 20, etc. For example, the smaller the average length of the recesses 32a in the extension direction relative to the average exposed length of the conductor 4 from the insulating layer 7, the more difficult it may be to increase the differential impedance at the connection portion 20. On the other hand, the larger the average length of the recesses 32a in the extension direction relative to the average exposed length of the conductor 4 from the insulating layer 7, the more likely the recesses 32a will be unnecessarily large, and the strength of the substrate 11 may be reduced. Specifically, the ratio of the average length of the recesses 32a in the extension direction to the average exposed length of the conductors 4 from the insulating layer 7 (hereinafter also referred to as the "eighth ratio") is preferably 100% or more and 300% or less, and more preferably 105% or more and 200% or less. When the eighth ratio satisfies the above range, the differential impedance at the connection portion 20 can be more reliably increased. Therefore, the transmission loss at the connection portion 20 can be more reliably reduced. Furthermore, a decrease in the strength of the substrate 11 can be reduced.

[0107] The cross-sectional shapes of the resin layer 32 and the recessed portion 32a are not particularly limited and can be set appropriately.

[0108] [Method for manufacturing electrical connection structure] The method for manufacturing an electrical connection structure of this embodiment includes a step of forming a resin layer 32 (and recesses 32a) instead of the step of forming the resin layer 30 in the second embodiment described above.

[0109] The process of forming the resin layer 32 can be performed using a known method. For example, a plate-shaped shielding member is inserted between adjacent connection portions 20 perpendicular to the substrate 11 and spaced apart from the substrate 11 by a distance corresponding to the thickness of the recess 32a, and the connection portions 20 and the shielding member are entirely surrounded by a frame-shaped member as described above. In this state, a molten resin material is poured into the frame-shaped member, cured, and then the frame-shaped member and the shielding member are removed, thereby forming the resin layer 32 and the recess 32a. Examples of materials for the shielding member include known fluororesins such as polytetrafluoroethylene (PTFE). Alternatively, for example, the resin layer 32 and the recess 32a can be formed by pouring a molten resin material into the frame-shaped member without using the shielding member, semi-curing or fully curing the surface of the poured resin material, and then pressing the resin material toward the substrate 11 with a plate-shaped press member while heating as necessary. Alternatively, the resin layer 32 and the recesses 32a can be formed by using a resin material with a relatively low viscosity and pouring the resin material into the frame-shaped member so as to form the resin layer 32 and the recesses 32a.

[0110] (advantage) In the electrical connection structure and the connection of the insulated wire and the printed wiring board of this embodiment, the transmission loss at the connection portion 20 is reduced.

[0111] In addition, since the grooves 13 are formed in the substrate 11, the projected distance is increased accordingly, and therefore the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment have improved insulation between the connection parts 20. Furthermore, since the grooves 13 are formed in the substrate 11, the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment are made lighter in weight.

[0112] Furthermore, in this embodiment, since the resin layer 32 is provided, the decrease in differential impedance at the connection portion 20 is suppressed, and the insulation of the connection portion 20 against the external environment is improved.

[0113] Furthermore, in this embodiment, since the resin layer 32 has the recesses 32a, the differential impedance at the connection portion 20 can be made larger than when the resin layer does not have the recesses.

[0114] [Fourth embodiment] [Electrical connection structure and connector] The electrical connection structure and connecting body of this embodiment include a plurality of resin layers 34 formed from the same material as the resin layer 32 of the third embodiment (i.e., the resin layer 30 of the first embodiment), and these resin layers 34 are partitioned by recesses 34a between the connecting portions 20. In this embodiment, the resin layer 34 covers the connecting portions 20 but does not cover the spaces between the connecting portions 20. The portions between the connecting portions 20 that are not covered by the resin layer 34 form the recesses 34a. Other than that, this embodiment has exactly the same configuration as the electrical connection structure and connecting body of the third embodiment. Therefore, only the configuration that differs from the third embodiment will be described for this embodiment. Furthermore, the same components as those in the second and third embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0115] <Resin layer> 6, in this embodiment, unlike the third embodiment described above, each of the connection portions 20 is covered with a plurality of resin layers 34. Specifically, a plurality of resin layers 34 are formed so as to cover each of the connection portions 20. In this embodiment, the resin layers 34 are formed with recesses 34a spaced apart at intervals corresponding to the spacing between the wirings 12.

[0116] Thus, this embodiment corresponds to a case where the average minimum thickness T3 of the recess 34a is 0, i.e., a case where the ratio (sixth ratio) of the average minimum thickness T3 of the recess 34a to the average thickness T2 of the connection portion 20 (see Figure 5) is 0.

[0117] The average thickness of the resin layer 34 directly above the connection portion 20, the average length of the resin layer 34 in the extending direction, and the average width of the first portion of the recess 34a can be set in the same manner as in the third embodiment described above.

[0118] [Method for manufacturing electrical connection structure] The method for manufacturing an electrical connection structure of this embodiment includes a step of forming a resin layer 34 (and recesses 34a) instead of the step of forming the resin layer 32 in the third embodiment described above.

[0119] The step of forming the resin layer 34 can be performed using a known method. For example, a plate-shaped shielding member as described above is inserted between adjacent connection portions 20 perpendicular to the substrate 11 so that its lower end covers the groove 13 formed in the substrate 11, and the connection portions 20 and the shielding member are entirely surrounded by a frame-shaped member as described above. In this state, a molten resin material is poured into the frame-shaped member, cured, and then the frame-shaped member and the shielding member are removed, thereby forming the resin layer 34 and the recess 34a. Alternatively, for example, the resin layer 34 and the recess 34a can be formed by pouring a molten resin material into the frame-shaped member without using the shielding member, semi-curing or fully curing the surface of the poured resin material, and pressing the frame-shaped member toward the substrate 11 while heating it as necessary, thereby displacing the resin material in the portion corresponding to the recess 34a.

[0120] In this embodiment, the spaces between the wirings 12, i.e., the spaces between the connection portions 20, are not covered with the resin layer 34, so that an air layer exists around the connection portions 20, thereby increasing the differential impedance at the connection portions 20.

[0121] (advantage) In the electrical connection structure and the connection of the insulated wire and the printed wiring board of this embodiment, the transmission loss at the connection portion 20 is reduced.

[0122] In addition, since the grooves 13 are formed in the substrate 11, the projected distance is increased accordingly, and therefore the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment have improved insulation between the connection parts 20. Furthermore, since the grooves 13 are formed in the substrate 11, the electrical connection structure and the connected body of the insulated electric wire and the printed wiring board of this embodiment are made lighter in weight.

[0123] Furthermore, the electrical connection structure of this embodiment, and the connection body of the insulated wire and the printed wiring board, are provided with a resin layer 34, which suppresses a decrease in differential impedance at the connection portion 20 while improving the insulation of the connection portion 20 against the external environment.

[0124] Furthermore, in this embodiment, the resin layer 34 covers each of the connection parts 20, and the spaces between the wirings 12 on the substrate 11, i.e., the spaces between the connection parts 20, are not covered with a resin layer, so the differential impedance of the connection parts 20 can be made larger than when a resin layer is present between the connection parts 20.

[0125] [Other embodiments] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the configurations of the above-described embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Example]

[0126] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0127] Example 1 A connection body of an insulated wire and a printed wiring board similar to that of the second embodiment shown in FIG. 4 was produced as a connection body of Example 1.

[0128] In the connection body of Example 1, a substrate material having an average thickness of 450 μm and a relative dielectric constant of 3.7 was used. Four wires were formed at equal intervals on this substrate material as multiple wires, and grooves were formed between the wires.

[0129] The average width of the groove opening is 200 μm, the average length in the extension direction is 1.0 mm, and the average depth is It was set to 100 μm.

[0130] While grooves were formed between the four wires on the substrate, no grooves were formed outside the four wires in the width direction.

[0131] The average width of the wires was set to 400 μm, the average spacing between adjacent wires was set to 200 μm, and the average thickness of the wires was set to 48 μm.

[0132] In this way, the ratio (first ratio) of the average width of the grooves located between adjacent wirings to the average spacing between these wirings was set to 100%, the ratio (second ratio) of the average length of the openings of the grooves in the extension direction to the average length in the extension direction of the connection between the wiring and the conductor was set to 100%, and the ratio (third ratio) of the average depth of the grooves to the average thickness of the wirings was set to 208%.

[0133] The insulated wire used had four conductors with a circular cross section, with the two outer conductors being ground wires and the two inner conductors being signal wires, and the circumferential surfaces of these conductors being collectively covered with an insulating layer. The average width and average thickness (average diameter) of the conductors were set to 270 μm. The average spacing between adjacent conductors was set according to the average spacing between the adjacent wiring.

[0134] These four conductors were bonded to the four wirings with Sn-Ag-Cu solder. The average length of the connection in the extension direction was set to 1.0 mm. The average thickness of the connection was 330 μm.

[0135] A UV-curable resin (product name SLD-5101, manufactured by Sanyu Rec Co., Ltd.) with a relative dielectric constant of 2.1 was melted, and the molten UV-curable resin was poured over the entire connection portion so that its upper surface was positioned above the connection portion and the upper surface was flat, and then cured to form a resin layer. The average thickness of the resin layer (average height from the substrate) was set to 430 μm. The average length of the resin layer in the extension direction was set to the same as the average length of the connection portion in the extension direction. In this way, a connection body similar to that of the second embodiment was obtained.

[0136] A current was passed from the wiring to the conductor in the connection of Example 1, and the change in differential impedance at each point over time was simulated. The results are shown in Figure 8. In Figure 8, R1 indicates the area of ​​the printed wiring board wiring alone (not connected to the conductor), R2 indicates the area of ​​the connection between the printed wiring board wiring and the conductor of the insulated wire, and R3 indicates the area of ​​the insulated wire conductor alone (not connected to the wiring). The time at the boundary between R1 and R2 was 150 ps, ​​and the time at the boundary between R2 and R3 was 240 ps.

[0137] (Comparative Example 1) As shown in FIG. 7, a connection body of Comparative Example 1 was fabricated in the same manner as in Example 1, except that a printed circuit board having a plurality of wirings 12 similar to those of Example 1 formed on a substrate 41 without grooves was used, and a resin layer 40 similar to that of Example 1 was formed except that it was not embedded in the grooves. The average thickness (average height from the substrate) of the resin layer in Comparative Example 1 was set to 430 μm. The change in differential impedance of the connection body of Comparative Example 1 was simulated in the same manner as in Example 1. The results are shown in FIG. 8.

[0138] As shown in Fig. 8, it was shown that the connection body of Example 1, in which grooves are formed in the substrate, can have a higher differential impedance at the connection portion than the connection body of Comparative Example 1, in which grooves are not formed in the substrate. Note that, from the results of Fig. 8, it can be reasonably inferred that by changing the shape of the resin layer as shown in Fig. 5 (third embodiment) and Fig. 6 (fourth embodiment), or by not forming a resin layer as shown in Fig. 3 (first embodiment), part of the resin layer is replaced with an air layer, and therefore the differential impedance at the connection portion can be made even larger than in the case shown in Fig. 8. [Industrial Applicability]

[0139] The present invention is applicable to the connection of insulated wires such as signal wires and ground wires, and can be suitably used for connecting insulated wires and printed wiring boards. [Explanation of symbols]

[0140] 1. Insulated wire 4 conductors 7. Insulation layer 10 Printed wiring board 11 Circuit Board 12 Wiring 13 Groove 20 Connection 21 Soldering section 30, 32, 34 Resin layer 32a Recess 41 Conventional board S Average spacing between wires W1 Average width of groove opening W2 Average width of the recessed portion that is smaller than the average thickness of the connection L1 Average length in the extension direction at the connection part L2 Average length of the groove in the extension direction D Average depth of groove T1 average wire thickness T2 Average thickness of the connection (total of wiring and conductor) T3 Average minimum recess thickness

Claims

1. An electrical connection structure between a plurality of conductors in an insulated wire having an insulating layer covering the circumferential surfaces of the plurality of conductors individually or collectively, and a plurality of wirings in a printed wiring board having a substrate and a plurality of wirings arranged at intervals on the substrate, the plurality of conductors are exposed at tip end regions in the extension direction of the plurality of conductors, and the exposed tip ends are superimposed on the plurality of wirings in a one-to-one correspondence to form connection portions on the substrate; the substrate has a groove formed between the adjacent connection portions, An electrical connection structure in which the average depth of the groove from the outer surface of the substrate is equal to or greater than the average thickness of the wiring.

2. 2. The electrical connection structure according to claim 1, wherein the ratio of the average width of the opening of the groove located between the adjacent wirings in a direction perpendicular to the extension direction to the average spacing between the adjacent wirings is 50% or more and 100% or less.

3. 3. The electrical connection structure according to claim 1, wherein a ratio of an average length of the opening of the groove in the extending direction to an average length of the connection portion in the extending direction is 90% or more and 110% or less.

4. 4. The electrical connection structure according to claim 1, wherein the connection portion has a solder portion that bonds the tip end of the conductor to the wiring.

5. Further provided is a resin layer covering the connection portion, the resin layer is formed of an insulating resin material having a dielectric constant smaller than that of the substrate, 5. The electrical connection structure according to claim 1, wherein a portion of the resin layer is embedded in the groove.

6. the resin layer has recesses that partition the resin layer between the adjacent connection portions, 6. The electrical connection structure according to claim 5, wherein the average minimum thickness of the recess from the substrate is smaller than the average thickness of the connection portion.

7. A connection body of an insulated wire and a printed wiring board, comprising the electrical connection structure according to any one of claims 1 to 6.

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