Connection structure

Abstract

This connection structure comprises a plurality of insulating wires, a base material, a plurality of to-be-connected sections disposed on the base material, and a sealing member. Each of the insulating wires has a center conductor and an insulating layer which covers the peripheral surface of the center conductor. On the leading end section in the axial direction of each of the plurality of insulating wires, the center conductor is exposed from the insulating layer. The plurality of to-be-connected sections are arranged side by side in a row shape. The leading end sections of the plurality of insulating wires are respectively soldered to the plurality of to-be-connected sections. The sealing member is disposed on the base material so as to cover the leading end sections of the plurality of insulating wires and the plurality of to-be-connected sections.

Description

Connection structure

[0001] The present disclosure relates to a connection structure.

[0002] For example, Japanese Patent Laid-Open Publication No. 2015-201280 (Patent Document 1) describes a connection structure that includes a plurality of insulated wires, a printed wiring board, and a positioning sheet.

[0003] The conductor of each of the multiple insulated wires is exposed from the insulating layer at its axial tip. The printed wiring board has multiple connection parts arranged in a row. The tip of each of the multiple insulated wires is soldered to a respective one of the multiple connection parts. The positioning sheet has an adhesive layer and a base film. The adhesive layer is adhered to the tip parts of the multiple insulated wires. The base film is disposed on the adhesive layer. The longitudinal direction of the positioning sheet is along the direction in which the multiple connection parts are arranged (the direction in which the conductors of the multiple insulated wires are arranged).

[0004] The connection structure described in Patent Document 1 is manufactured by the following method. First, a positioning step is performed. A jig is used in the positioning step. A plurality of positioning grooves are formed on the surface of the jig. The pitch between two adjacent ones of the plurality of positioning grooves is equal to the pitch between two adjacent ones of the plurality of connected parts. The tip ends of the plurality of insulated wires are placed in the respective positioning grooves.

[0005] Second, a positioning sheet is attached to the conductor. At this time, the adhesive layer is adhered to the tip ends of the multiple insulated wires. Third, the tip ends of each of the multiple insulated wires are placed on each of the multiple connection parts, and the adhesive layers at both longitudinal ends of the positioning sheet are adhered to the printed wiring board. Fourth, the tip ends of each of the multiple insulated wires are soldered to each of the multiple connection parts.

[0006] Japanese Patent Application Laid-Open No. 2015-201280

[0007] The connection structure disclosed herein includes a plurality of insulated wires, a substrate, a plurality of connectable parts disposed on the substrate, and a sealing member. Each of the plurality of insulated wires has a center conductor and an insulating layer covering the circumferential surface of the center conductor. At the axial end of each of the plurality of insulated wires, the center conductor is exposed from the insulating layer. The plurality of connectable parts are arranged in a row. The end of each of the plurality of insulated wires is soldered to a respective one of the plurality of connectable parts. The sealing member is disposed on the substrate so as to cover the end ends of the plurality of insulated wires and the plurality of connectable parts.

[0008] FIG. 1 is a plan view of the connection structure 100. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a manufacturing process diagram of the connection structure 100. FIG. 6 is a cross-sectional view illustrating the positioning step S2. FIG. 7 is a cross-sectional view illustrating the bonding step S3. FIG. 8 is a plan view illustrating the bonding step S3. FIG. 9A is a first cross-sectional view illustrating the soldering step S4. FIG. 9B is a second cross-sectional view illustrating the soldering step S4. FIG. 9C is a plan view illustrating the soldering step S4. FIG. 10 is a cross-sectional view illustrating the peeling step S5. FIG. 11 is a side view of an insulated wire 20 used in the connection structure 100 according to Modification 1. FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11. FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 11. FIG. 14 is a cross-sectional view of an insulated wire 20 used in the connection structure 100 according to Modification 2. Fig. 15 is a cross-sectional view of the connection structure 100 according to the modified example 2. Fig. 16 is a plan view illustrating the soldering step S4 in the manufacturing method of the connection structure 100 according to the modified example 3.

[0009] [Problem to be Solved by the Present Disclosure] In the connection structure described in Patent Document 1, there is a space between two adjacent tip ends of the multiple insulated electric wires, and therefore, in the connection structure described in Patent Document 1, there is room for improvement in the reliability of the connection between each tip end of the multiple insulated electric wires and each of the multiple connected parts.

[0010] The present disclosure has been made in view of the above-described problems of the conventional art. More specifically, the present disclosure provides a connection structure that can improve the reliability of connections between the tip ends of each of a plurality of insulated electric wires and each of a plurality of connected parts.

[0011] Effect of the Present Disclosure The connection structure of the present disclosure can improve the reliability of the connection between the tip end of each of the plurality of insulated wires and each of the plurality of connected parts.

[0012] [Outline of the embodiment] First, the embodiments of the present disclosure will be listed and described.

[0013] (1) According to one embodiment, the connector includes a plurality of insulated wires, a substrate, a plurality of connectable parts disposed on the substrate, and a sealing member. Each of the plurality of insulated wires has a central conductor and an insulating layer covering the circumferential surface of the central conductor. At the axial end of each of the plurality of insulated wires, the central conductor is exposed from the insulating layer. The plurality of connectable parts are arranged in a row. The end of each of the plurality of insulated wires is soldered to a respective one of the plurality of connectable parts. The sealing member is disposed on the substrate so as to cover the end portions of the plurality of insulated wires and the plurality of connectable parts.

[0014] According to the connection structure of (1) above, it is possible to improve the reliability of the connection between the tip end of each of the plurality of insulated wires and each of the plurality of connected parts.

[0015] (2) The connection structure of (1) may further include an adhesive. The adhesive may be attached to a side surface of the tip end of at least one of the plurality of insulated electric wires.

[0016] According to the connection structure of (2) above, it is possible to prevent the positions of the tip ends of the plurality of insulated wires and the positions of the plurality of connected portions from becoming misaligned with each other during soldering.

[0017] (3) In the connection structure of (2) above, the adhesive may be attached to the tip portion of at least one of the plurality of insulated electric wires up to a portion of the peripheral surface of the tip portion that is a distance from the upper end of the tip portion that is greater than the smaller of 1 / 10 of the average diameter of the tip portion and 3 μm.

[0018] (4) In the connection structure of (2) above, the adhesive may be attached to the tip portion of at least one of the plurality of insulated electric wires up to a portion of the peripheral surface of the tip portion that is a distance from the upper end of the tip portion that is greater than the smaller of 1 / 3 of the average diameter of the tip portion and 10 μm.

[0019] (5) In the connection structures of (1) to (4) above, the pitch between two adjacent ones of the plurality of connected portions may be 200 μm or less.

[0020] (6) In the connection structures (1) to (5) above, the thickness of the sealing member on the tip portion may be 100 μm or less.

[0021] According to the connection structure of (6) above, it is possible to reduce the height of the connection portion between the tip end of each of the plurality of insulated wires and each of the plurality of connected portions.

[0022] [Details of the embodiment] The details of the embodiment of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated. The connection structure according to the embodiment is referred to as a connection structure 100.

[0023] (Configuration of connection structure 100) The configuration of the connection structure 100 will be described below. Fig. 1 is a plan view of the connection structure 100. As shown in Fig. 1, the connection structure 100 has a printed wiring board 10, a plurality of insulated wires 20, and a sealing member 70. Although not shown, the plurality of insulated wires 20 are obtained by dividing a single wire assembly.

[0024] Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 2, the printed wiring board 10 has a substrate 11 and a plurality of wirings 12.

[0025] The substrate 11 has a first main surface 11a and a second main surface 11b. The first main surface 11a and the second main surface 11b are end surfaces in the thickness direction of the substrate 11. The substrate 11 is in the form of a plate or a film, and is made of an electrically insulating material. The substrate 11 is made of, for example, a resin material. When the substrate 11 is in the form of a plate, the substrate 11 is made of, for example, glass epoxy. When the substrate 11 is in the form of a film, the substrate 11 is made of, for example, polyimide, polyethylene terephthalate, etc. The constituent material of the substrate 11 may contain fillers, additives, etc.

[0026] The wiring 12 is disposed on the first major surface 11a. The wiring 12 extends along a first direction DR1 in a plan view. "Plan view" refers to a view from a direction perpendicular to the first major surface 11a. The multiple wirings 12 are arranged at intervals in a second direction DR2. It is preferable that the multiple wirings 12 are arranged at equal intervals in the second direction DR2. The second direction DR2 is a direction perpendicular to the first direction DR1.

[0027] The ends of the wiring 12 in the first direction DR1 form connection pads 12a. The connection pads 12a serve as connection receiving portions to which the tip portions 20a are connected. The connection pads 12a of the multiple wirings 12 are arranged at intervals in the second direction DR2. The connection pads 12a of the multiple wirings 12 are preferably arranged at equal intervals. The pitch between two adjacent connection pads 12a of the multiple wirings 12 is defined as pitch P. The pitch P is the distance between the center of one connection pad 12a in the second direction DR2 and the center of another connection pad 12a adjacent to that connection pad 12a in the second direction DR2. The pitch P is preferably 200 μm or less. Although not shown, the surfaces of the connection pads 12a may be plated with tin (Sn) plating, gold (Au) plating, or the like.

[0028] The wiring 12 is formed of a conductive material. The wiring 12 is formed of, for example, copper (Cu) or a copper alloy. The wiring 12 is formed, for example, by etching a conductive material disposed on the substrate 11 using a resist pattern as a mask. However, the method for forming the wiring 12 is not limited to this.

[0029] The lower limit of the average thickness of the wiring 12 is preferably 3 μm, and more preferably 5 μm, from the viewpoint of reducing the resistance of the wiring 12. The upper limit of the average thickness of the wiring 12 is preferably 100 μm, and more preferably 50 μm, from the viewpoint of reducing the height of the connection structure 100.

[0030] From the viewpoint of ensuring connectivity with the center conductor 21, the lower limit of the average width of the connection pad 12a is preferably 0.8 times the average diameter of the center conductor 21, and more preferably 1.0 times the average diameter of the center conductor 21. From the viewpoint of reducing the width of the connection structure 100, the upper limit of the average width of the connection pad 12a is preferably 5.0 times the average diameter of the center conductor 21, and more preferably 3.0 times the average diameter of the center conductor 21, and particularly preferably 2.0 times the average diameter of the center conductor 21.

[0031] 3 is a cross-sectional view taken along line III-III in FIG. 1. As shown in FIG. 3, the insulated wire 20 includes a central conductor 21 and an insulating layer 22. The central conductor 21 is made of a conductive material. The central conductor 21 is a metal wire made of, for example, copper, a copper alloy, aluminum (Al), an aluminum alloy, or the like. The central conductor 21 has, for example, a circular shape in a cross section perpendicular to the axial direction. The "axial direction" refers to the direction in which the insulated wire 20 extends. The cross-sectional shape of the central conductor 21 is not limited to this. The central conductor 21 may also have, for example, a square or rectangular shape.

[0032] The lower limit of the average diameter of the central conductor 21 is preferably 10 μm, and more preferably 15 μm, from the viewpoint of suppressing breakage of the central conductor 21. The upper limit of the average diameter of the central conductor 21 is preferably 500 μm, and more preferably 200 μm, from the viewpoint of miniaturizing the connection structure 100.

[0033] The insulating layer 22 covers the circumferential surface of the central conductor 21. The insulating layer 22 is formed of a flexible, electrically insulating material. The insulating layer 22 may be made of, for example, ethylene resin, a resin obtained by mixing ethylene resin with polyolefin, polyimide, polyamide-imide, polyurethane, a silane-crosslinked resin composition, or a fluororesin. Specific examples of ethylene resins include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer. Specific examples of polyolefins include polypropylene, ethylene-propylene rubber, and styrene elastomer. Specific examples of fluororesins include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), and FEP (perfluoroethylene propene copolymer).

[0034] The insulating layer 22 is disposed on the peripheral surface of the central conductor 21, for example, by extruding the constituent material of the insulating layer 22 in a molten state onto the peripheral surface of the central conductor 21 and hardening it, or by applying a paint prepared by dissolving the constituent material of the insulating layer 22 in an organic solvent onto the peripheral surface of the central conductor 21 and then baking it. The average thickness of the insulating layer 22 is, for example, 3 μm or more and 1 mm or less.

[0035] 1 , the insulated wire 20 has a tip portion 20a in the axial direction. In the tip portion 20a, the insulating layer 22 is removed from the peripheral surface of the central conductor 21. That is, the tip portion 20a is composed of the central conductor 21. The average length of the tip portion 20a in the axial direction is, for example, 0.2 mm or more and 3.0 mm or less.

[0036] Although not shown, a primer layer may be interposed between the peripheral surface of the central conductor 21 and the insulating layer 22 in order to improve adhesion between the peripheral surface of the central conductor 21 and the insulating layer 22. The primer layer is formed, for example, by curing a crosslinkable resin such as ethylene that does not contain metal hydroxide.

[0037] 4 is a cross-sectional view taken along line IV-IV in FIG. 1. As shown in FIG. 4, the tip end 20a of each of the multiple insulated wires 20 is connected to each of the multiple connection pads 12a by a connecting portion 40. The connecting portion 40 is formed of a solder alloy such as a tin-silver-copper alloy, a tin-zinc (Zn)-bismuth (Bi) alloy, a tin-copper alloy, or a tin-silver-indium (In)-bismuth alloy. In other words, the tip end 20a of each of the multiple insulated wires 20 is soldered to each of the multiple connection pads 12a.

[0038] The tip portion 20a has an upper end 20b. The distance between the tip portion 20a and the first main surface 11a in the third direction DR3 is greatest at the upper end 20b. The third direction DR3 is a direction perpendicular to the first direction DR1 and the second direction DR2. The third direction DR3 corresponds to the normal direction of the first main surface 11a. An adhesive 32 may be adhered to a side surface of at least one tip portion 20a of the multiple insulated electric wires 20. For example, the adhesive 32 may be adhered to a side surface of at least one tip portion 20a of the multiple insulated electric wires 20 other than both ends in the second direction DR2. "The adhesive 32 is adhered to the side surface of the tip portion 20a" means that the adhesive 32 is adhered to a portion of the peripheral surface of the tip portion 20a whose distance from the upper end 20b in the third direction DR3 is greater than the smaller of 1 / 10 of the average diameter of the tip portion 20a (center conductor 21) and 3 μm. The adhesive 32 may be adhered to the portion of the peripheral surface of the tip portion 20a whose distance from the upper end 20b in the third direction DR3 is greater than the smaller of 1 / 3 of the average diameter of the tip portion 20a (center conductor 21) and 10 μm.

[0039] The sealing member 70 is disposed on the first main surface 11a so as to cover the tip ends 20a of the insulated wires 20 and the connection pads 12a. The sealing member 70 is formed of, for example, an ultraviolet-curable resin material. The thickness of the sealing member 70 on the tip ends 20a is defined as thickness T. Thickness T is preferably 100 μm or less.

[0040] (Method of manufacturing the connection structure 100) A method of manufacturing the connection structure 100 will be described below. FIG. 5 is a manufacturing process diagram of the connection structure 100. As shown in FIG. 5, the method of manufacturing the connection structure 100 includes a preparation step S1, a positioning step S2, a bonding step S3, a soldering step S4, a peeling step S5, and a sealing step S6. The positioning step S2 is performed after the preparation step S1. The bonding step S3 is performed after the positioning step S2. The soldering step S4 is performed after the bonding step S3. The peeling step S5 is performed after the soldering step S4. The sealing step S6 is performed after the peeling step S5.

[0041] In the preparation step S1, a plurality of insulated wires 20 are prepared. In the preparation step S1, first, the plurality of insulated wires 20 are divided from a wire assembly. Second, the insulating layer 22 is removed from the tip portion 20a. The insulating layer 22 is removed by irradiating a laser to cut the insulating layer 22 and peeling off the cut insulating layer 22.

[0042] Fig. 6 is a cross-sectional view illustrating the positioning step S2. As shown in Fig. 6, the positioning step S2 is performed using a jig 50. The jig 50 is placed on a base 51. The jig 50 has a first surface 50a and a second surface 50b. The first surface 50a faces the base 51. The second surface 50b is the surface opposite to the first surface 50a.

[0043] A plurality of positioning grooves 50c are formed on the second surface 50b. The positioning grooves 50c extend linearly. In a cross-sectional view perpendicular to the extending direction of the positioning grooves 50c, the positioning grooves 50c are, for example, V-shaped. In a cross-sectional view perpendicular to the extending direction of the positioning grooves 50c, the positioning grooves 50c may be U-shaped. The plurality of positioning grooves 50c are arranged at intervals in a direction perpendicular to the extending direction of the positioning grooves 50c. The pitch between two adjacent ones of the plurality of positioning grooves 50c is set to match the pitch P. In the positioning step S2, the tip ends 20a of the plurality of insulated electric wires 20 are arranged in the plurality of positioning grooves 50c, respectively. As a result, the pitch between two adjacent tip ends 20a of the plurality of insulated electric wires 20 is adjusted to match the pitch P.

[0044] 7 is a cross-sectional view illustrating the bonding step S3. As shown in FIG. 7, in the bonding step S3, the pitch-fixing film 30 is bonded to the tip ends 20a of the plurality of insulated wires 20 using an adhesive 32.

[0045] The pitch fixing film 30 has a base material 31 and an adhesive 32. The base material 31 is, for example, a film-like member. The base material 31 has a first main surface 31a and a second main surface 31b. The first main surface 31a and the second main surface 31b are end surfaces in the thickness direction of the base material 31. The first main surface 31a faces the base material 11 (printed wiring board 10).

[0046] The lower limit of the average thickness of the substrate 31 is preferably 5 μm, and more preferably 10 μm, from the viewpoint of ensuring the strength of the substrate 31. The upper limit of the average thickness of the substrate 31 is preferably 100 μm, and more preferably 50 μm, from the viewpoint of reducing the height of the connection structure 100.

[0047] The substrate 31 is formed of, for example, a super engineering plastic. Specific examples of the super engineering plastic include polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, liquid crystal polymer, polysulfone, polyethersulfone, and fluororesins other than polytetrafluoroethylene.

[0048] The adhesive 32 is arranged in a layer on the first main surface 31a. The adhesive 32 has a first surface 32a and a second surface 32b. The first surface 32a is the surface in contact with the base material 31 (first main surface 31a). The second surface 32b is the surface opposite to the first surface 32a. The average thickness of the adhesive 32 is, for example, smaller than the average thickness of the base material 31. From the viewpoint of ensuring the strength of the adhesive 32, the lower limit of the average thickness of the adhesive 32 is preferably 5 μm, and more preferably 10 μm. From the viewpoint of reducing the height of the connection structure 100, the average thickness of the adhesive 32 is preferably 100 μm, and more preferably 50 μm.

[0049] The adhesive 32 is, for example, a thermosetting adhesive containing a thermosetting resin as a main component. The thermosetting resin is, for example, an epoxy resin containing a curing agent. Specific examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol A type and bisphenol F type copolymer epoxy resin, naphthalene type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin. The adhesive 32 may contain at least one of these epoxy resins.

[0050] As the molecular weight of the epoxy resin increases, the formability and melt viscosity of the resin at the joining temperature tend to increase. On the other hand, as the molecular weight of the epoxy resin decreases, the crosslink density tends to increase, improving heat resistance. Furthermore, as the molecular weight of the epoxy resin decreases, it tends to react more quickly with the curing agent when heated, improving adhesive performance. Therefore, it is preferable that the epoxy resin used in the adhesive 32 be a combination of an epoxy resin with a molecular weight of 15,000 or more and an epoxy resin with a molecular weight of 2,000 or less. Here, the molecular weight of the epoxy resin is the polystyrene-equivalent molecular weight determined by gel permeation chromatography (GPC) using tetrahydrofuran (THF) development.

[0051] As the curing agent contained in the epoxy resin, for example, a latent curing agent is used. Latent curing agents have excellent storage stability at low temperatures and undergo almost no curing reaction at room temperature, but rapidly undergo a curing reaction when exposed to heat, light, or the like. Specific examples of latent curing agents include imidazole-based, hydrazide-based, boron trifluoride-amine complex, amine-based compounds such as amines (e.g., amine imides, polyamines, tertiary amines, and alkyl ureas), dicyandiamide-based, acid anhydride-based, and phenol-based compounds, and modified products thereof. One or a mixture of two or more of these can be used as the curing agent for the epoxy resin.

[0052] As the curing agent contained in the epoxy resin, an imidazole-based latent curing agent is preferred from the viewpoints of low-temperature storage stability and fast curing. Specific examples of imidazole-based latent curing agents include adducts of imidazole compounds with epoxy resins. Specific examples of imidazole compounds include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-dodecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 4-methylimidazole.

[0053] From the viewpoint of long-term storage stability and rapid curing, it is preferable that the imidazole-based latent curing agent is microencapsulated. The microcapsules are formed from a polymeric material, a metallic material, or an inorganic material. Specific examples of the polymeric material include polymeric materials mainly composed of polyurethane, polyester, etc. Specific examples of the metallic material include nickel, copper, etc. Specific examples of the inorganic material include calcium silicate, etc.

[0054] The adhesive 32 may be a thermoplastic adhesive containing a thermoplastic resin as a main component. Specific examples of thermoplastic resins include polyvinyl acetals such as polyvinyl butyral, phenoxy resins, acrylic resins, methacrylic resins, polyamides, polyacetals, polyphenylene sulfide, polyimides, polytetrafluoroethylene, polyether ether ketones, polyether sulfones, urethanes, polyesters, polyethylenes, polypropylenes, and polystyrenes. The thermoplastic resin is preferably a phenoxy resin, polyamide, or polyimide.

[0055] The substrate 31 and the adhesive 32 are preferably transparent, which allows the tip portion 20a to be seen through the substrate 31 and the adhesive 32, thereby improving the manufacturability of the connection structure 100.

[0056] The adhesive 32 is adhered to the side surface of the tip portion 20a. That is, the adhesive 32 is adhered up to the peripheral surface of the tip portion 20a whose distance from the upper end 20b is greater than the smaller of 1 / 10 of the average diameter of the tip portion 20a (center conductor 21) or 3 μm. From another perspective, the distance between the upper end 20b and the second surface 32b is greater than the smaller of 1 / 10 of the average diameter of the tip portion 20a (center conductor 21) or 3 μm.

[0057] The lower limit of the thickness of adhesive 32 between upper end 20b and substrate 31 is preferably 1 / 10 of the average diameter of center conductor 21, and more preferably 1 / 5 of the average diameter of center conductor 21, from the viewpoint of sufficiently fixing center conductor 21 with adhesive 32. The thickness of adhesive 32 between upper end 20b and substrate 31 is preferably 2 / 3 of the average diameter of center conductor 21, and more preferably 1 / 2 of the average diameter of center conductor 21, from the viewpoint of reducing the height of connection structure 100. However, upper end 20b may be in contact with substrate 31. That is, the lower limit of the thickness of adhesive 32 between upper end 20b and substrate 31 may be 0.

[0058] The adhesive strength between the tip 20a and the adhesive 32 is preferably less than the bond strength between the tip 20a and the connection pad 12a.

[0059] Fig. 8 is a plan view illustrating the bonding step S3. As shown in Fig. 8, the tip portions 20a protrude from the pitch-fixed film 30 in a plan view. The lower limit of the length of the tip portions 20a protruding from the pitch-fixed film 30 is preferably 10 µm, and more preferably 20 µm. The upper limit of the length of the tip portions 20a protruding from the pitch-fixed film 30 is preferably 200 µm, and more preferably 150 µm.

[0060] The insulating layer 22 adjacent to the tip portion 20a overlaps the pitch-fixed film 30 in a plan view. That is, the insulating layer 22 adjacent to the tip portion 20a is adhered with an adhesive 32. As a result, the boundary between the insulating layer 22 adjacent to the tip portion 20a and the tip portion 20a is protected by the adhesive 32. The lower limit of the overlap width between the insulating layer 22 adjacent to the tip portion 20a and the pitch-fixed film 30 is preferably 10 μm, and more preferably 20 μm. The upper limit of the overlap width between the insulating layer 22 adjacent to the tip portion 20a and the pitch-fixed film 30 is preferably 500 μm, and more preferably 300 μm.

[0061] In the bonding step S3, first, the pitch-fixing film 30 is placed on the tip ends 20a of the insulated wires 20. At this time, the tip ends 20a of the insulated wires 20 are in contact with the adhesive 32. At this stage, the adhesive 32 has not yet hardened.

[0062] Second, a heating element 60 is brought into contact with the first main surface 31a, and the heating element 60 presses the pitch-fixing film 30 toward the tip ends 20a of the insulated wires 20. As a result, the side surfaces of the tip ends 20a of the insulated wires 20 are bonded to the adhesive 32, and the tip ends 20a of the insulated wires 20 are fixed to one another. If the adhesive 32 is a thermosetting adhesive, the adhesive 32 is brought into a B-stage state by heating with the heating element 60. After the bonding step S3 is performed, the jig 50 is removed. Because the tip ends 20a of the insulated wires 20 are fixed to one another in the bonding step S3, the pitch between two adjacent insulated wires 20 is unlikely to change even after the jig 50 is removed.

[0063] 9A is a first cross-sectional view illustrating the soldering step S4. FIG. 9B is a second cross-sectional view illustrating the soldering step S4. As shown in FIG. 9A and FIG. 9B, in the soldering step S4, the connection portion 40 is formed, and the tip end 20 a of each of the multiple insulated wires 20 is soldered to each of the multiple connection pads 12 a. In the soldering step S4, first, the tip end 20 a of each of the multiple insulated wires 20 is placed on each of the multiple connection pads 12 a with plate-shaped solder 41 interposed therebetween.

[0064] The heating temperature in the bonding step S3 may be a temperature at which the viscosity of the adhesive 32 decreases so that a portion of the tip portion 20a is embedded in the adhesive 32. The heating temperature in the bonding step S3 is, for example, 170°C or higher and 350°C or lower, and preferably 200°C or higher and 320°C or lower. The pressure applied in the bonding step S3 may be a pressure at which a portion of the tip portion 20a is embedded in the softened adhesive 32. The pressure applied in the bonding step S3 is, for example, 0.1 MPa or higher and 15 MPa or lower, and preferably 0.5 MPa or higher and 10 MPa or lower. Note that if the heating temperature in the bonding step S3 and the pressure applied in the bonding step S3 are too high, the tip portion 20a will be too embedded in the adhesive 32 (i.e., the tip portion 20a will be covered by the adhesive 32), making it impossible to connect the tip portion 20a to the connection pad 12a. On the other hand, if the heating temperature in the bonding step S3 and the pressure applied in the bonding step S3 are too small, the tip portions 20a will not be embedded in the adhesive 32 (i.e., the adhesive 32 will not adhere to the sides of the tip portions 20a), and the force maintaining the pitch between the tip portions 20a of two adjacent insulated wires 20 will be weak.

[0065] Second, the heating element 61 is brought into contact with the first main surface 31a, and the heating element 61 presses the pitch-fixing film 30 toward the tip ends 20a of the insulated wires 20. This melts the solder plate 41, soldering the tip ends 20a of the insulated wires 20 to the connection pads 12a. Note that a solder bar may be used instead of the solder plate 41. Flux may also be applied to at least one of the surfaces of the solder plate 41 (solder bar), the tip ends 20a, and the connection pads 12a. This flux may be, for example, an organic acid-based or rosin-based flux. Although not shown, the solder plate 41 (solder bar) may be melted and soldered by bringing the heating element 61 into contact with the second main surface 11b.

[0066] 9C is a plan view illustrating the soldering step S4. As shown in FIG. 9C , the pitch-fixing film 30 at least partially overlaps the multiple connection pads 12a in a plan view. Both end portions of the pitch-fixing film 30 in the second direction DR2 are positioned to protrude outward from the outermost connection pads 12a in the second direction DR2. The lower limit of the protrusion amount of both end portions of the pitch-fixing film 30 in the second direction DR2 is preferably twice the average diameter of the center conductors 21, more preferably 2.5 times the average diameter of the center conductors 21. The upper limit of the protrusion amount of both end portions of the pitch-fixing film 30 in the second direction DR2 is preferably 100 times the average diameter of the center conductors 21, more preferably 50 times the average diameter of the center conductors 21. During the soldering step S4, both end portions of the pitch-fixing film 30 in the second direction DR2 may or may not be adhered to the first main surface 11a.

[0067] 10 is a cross-sectional view illustrating the peeling step S5. As shown in FIG. 10 , in the peeling step S5, the pitch-fixing film 30 is peeled off from the tip end 20 a of the insulated wires 20 together with the adhesive 32. However, even when the peeling step S5 is performed, the adhesive 32 may not be completely peeled off, and therefore, the adhesive 32 may partially remain on the side surface of the tip end 20 a of at least one of the insulated wires 20.

[0068] In the sealing step S6, the tip ends 20a of the insulated wires 20 and the connection pads 12a are covered with the sealing member 70. In the sealing step S6, first, the sealing member 70 is supplied onto the first main surface 11a so as to cover the tip ends 20a of the insulated wires 20 and the connection pads 12a. At this stage, the sealing member 70 is uncured. Second, ultraviolet rays are irradiated onto the uncured sealing member 70. This cures the sealing member 70, and the tip ends 20a of the insulated wires 20 and the connection pads 12a are sealed with the sealing member 70. In this manner, the connection structure 100 having the structure shown in FIGS. 1 to 4 is formed.

[0069] (Effects of Connection Structure 100) The following describes the effects of the connection structure 100. In the connection structure 100, the sealing member 70 is disposed on the first main surface 11a so as to cover the tip ends 20a of the multiple insulated wires 20 and the multiple connection pads 12a, and therefore the sealing member 70 is also filled between two adjacent tip ends 20a of the multiple insulated wires 20. Therefore, the connection structure 100 can improve the reliability of the connection between the tip ends 20a and the connection pads 12a.

[0070] As described in Patent Document 1, when only the upper ends 20b of the tip portions 20a of the insulated wires 20 are adhered to the adhesive 32, the position of each of the tip portions 20a of the insulated wires 20 may not be sufficiently fixed. As a result, when soldering is performed, the position of each of the tip portions 20a of the insulated wires 20 may be misaligned with the position of each of the connection pads 12a, resulting in defective soldering. This problem is particularly noticeable when the pitch P is small (for example, when the pitch P is 200 μm or less).

[0071] On the other hand, in the connection structure 100, in the bonding step S3, the adhesive 32 is bonded to the side surfaces of the tip portions 20a of the multiple insulated wires 20. Therefore, in the connection structure 100, the position of each of the tip portions 20a of the multiple insulated wires 20 is more firmly fixed by the adhesive 32. As a result, with the connection structure 100, the position of each of the tip portions 20a of the multiple insulated wires 20 is less likely to deviate from the position of each of the multiple connection pads 12a during soldering, making it possible to prevent defective soldering.

[0072] In the connection structure 100, the pitch-fixing film 30 is peeled off from the tip ends 20 a of the multiple insulated wires 20. However, once the soldering step S4 is completed, there is no longer any need to fix the tip ends 20 a of the multiple insulated wires 20 to one another with the adhesive 32. Therefore, in the connection structure 100, the pitch-fixing film 30 is peeled off after the soldering step S4 is completed, and therefore, even without the pitch-fixing film 30, the position of each of the tip ends 20 a of the multiple insulated wires 20 is prevented from shifting from the position of each of the multiple connection pads 12 a during soldering.

[0073] In the connection structure described in Patent Document 1, the adhesive layers at both longitudinal ends of the positioning sheet are adhered to the printed wiring board to ensure a more secure connection between the tip end of the insulated wire and the connected portion. Therefore, the connection structure described in Patent Document 1 does not anticipate peeling the positioning sheet from the tip end of the insulated wire.

[0074] In the connection structure 100, the pitch fixing film 30 is peeled off, and therefore it is possible to reduce the height by the amount corresponding to the absence of the pitch fixing film 30. Note that, in the connection structure 100, the height of the portion where the tip portion 20a and the connection pad 12a are connected increases by the amount corresponding to the presence of the sealing member 70, but as long as the thickness T is 100 μm or less, this does not hinder the reduction in height.

[0075] (Variation 1) Fig. 11 is a side view of an insulated wire 20 used in a connection structure 100 according to Variation 1. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11 . As shown in Figs. 11 and 12 , the central conductor 21 may be a stranded wire formed by twisting together a plurality of strands 21a. In this case, the average diameter of the tip portion 20a is determined based on a virtual circumscribing circle (shown by a dotted line in Fig. 12 ) that circumscribes the plurality of strands 21a, and whether or not adhesive 32 is applied to the side surface of the tip portion 20a is determined based on the average diameter of the tip portion 20a determined based on the circumscribing circle. The number of strands 21a constituting the central conductor 21 is not particularly limited, but may be, for example, 2 to 20.

[0076] FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 11 . As shown in FIG. 13 , the insulated wire 20 may further include a plurality of outer conductors 23 and an outer sheath 24. That is, the insulated wire 20 may be a coaxial wire. The outer conductor 23 is, for example, a metal wire made of copper or a copper alloy. The surface of this metal wire may be plated with silver, tin, or the like to form the outer conductor 23. The outer conductor 23 extends along the axial direction on the circumferential surface of the insulating layer 22. The outer conductor 23 may be wound in a spiral shape. The plurality of outer conductors 23 are arranged along the circumferential surface of the insulating layer 22 to cover the insulating layer 22. The cross-sectional shape of the outer conductor 23 may be, for example, circular, square, rectangular, or the like.

[0077] The lower limit of the average diameter of the outer conductor 23 is preferably 10 μm, and more preferably 15 μm, from the viewpoint of preventing breakage of the outer conductor 23. The upper limit of the average diameter of the outer conductor 23 is preferably 500 μm, and more preferably 200 μm, from the viewpoint of preventing the outer diameter of the insulated wire 20 from becoming excessively large.

[0078] The outer jacket 24 covers the multiple outer conductors 23. The outer jacket 24 is made of a flexible, electrically insulating material. The outer jacket 24 is made of, for example, a polyester resin such as polyethylene terephthalate. The outer jacket 24 may be made of the same material as the insulating layer 22. The insulated wire 20 has an adjacent portion 20c in the axial direction adjacent to the tip portion 20a. At the tip portion 20a, the insulating layer 22, the multiple outer conductors 23, and the outer jacket 24 are removed, exposing the center conductor 21. At the adjacent portion 20c, the outer jacket 24 is removed, exposing the multiple outer conductors 23. Note that, on the tip portion 20a side of the adjacent portion 20c, the multiple outer conductors 23 are also removed.

[0079] The plurality of external conductors 23 exposed in the adjacent portions 20 c are electrically connected to a ground line (not shown) arranged on the first main surface 11 a by soldering or the like, and are set to a ground potential, thereby functioning as a shield to suppress electrical interference from other circuits. The average length of the adjacent portions 20 c in the axial direction is, for example, 0.1 mm or more and 5 mm or less.

[0080] If the insulated wire 20 has multiple outer conductors 23 and an outer jacket 24, in the preparation step S1, before the insulating layer 22 at the tip portion 20a is removed, the outer jacket 24 at the tip portion 20a and the adjacent portion 20c and the multiple outer conductors 23 at the tip portion 20a are removed.

[0081] (Variation 2) Fig. 14 is a cross-sectional view of an insulated wire 20 used in a connection structure 100 according to Variation 2. As shown in Fig. 14, the tip portion 20a may be composed of a center conductor 21 and a solder layer 42 covering the center conductor 21. In this case, the average diameter and the upper end of the solder layer 42 respectively define the average diameter and upper end 20b of the tip portion 20a, and whether or not the adhesive 32 is adhered to the side surface of the tip portion 20a is determined based on these. The solder layer 42 is formed by supplying a molten solder alloy onto the circumferential surface of the center conductor 21 in the tip portion 20a after the insulating layer 22 is removed in the preparation step S1.

[0082] FIG. 15 is a cross-sectional view of the connection structure 100 according to Modification 2. FIG. 15 shows a cross-section of the connection structure 100 according to Modification 2 at a position corresponding to FIG. 4. As shown in FIG. 15, the surface of the connection pad 12a may be covered with a solder layer 43. The solder layer 43 is formed, for example, by plating the surface of the connection pad 12a. The solder layers 42 and 43 are joined to each other by heating in the soldering step S4 to form the connection portion 40. Note that, when the tip portion 20a has the solder layer 42 and the surface of the connection pad 12a is covered with the solder layer 43, the plate-shaped solder 41 (bar-shaped solder) is not used in the soldering step S4, and flux is supplied to at least one of the surfaces of the solder layer 42 and the solder layer 43.

[0083] 16 is a plan view illustrating the soldering step S4 in the manufacturing method of the connection structure 100 according to Modification 3. As shown in Fig. 16, the pitch fixing film 30 does not have to overlap the multiple connection pads 12a in plan view.

[0084] (Variation 4) The adhesive 32 does not need to be placed on the base material 31 in advance. That is, in the bonding step S3, the base material 31 may be attached onto the adhesive 32 after the adhesive 32 is bonded to the tip ends 20 a of the multiple insulated wires 20.

[0085] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not the above-described embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0086] 10 Printed wiring board, 11a First main surface, 11b Second main surface, 11 Base material, 12 Wiring, 12a Connection pad, 20 Insulated wire, 20a Tip portion, 20b Upper end, 20c Adjacent portion, 21 Center conductor, 21a Wire, 22 Insulating layer, 23 Outer conductor, 30 Pitch fixing film, 31 Base material, 31a First main surface, 31b Second main surface, 32 Adhesive, 32a First surface, 32b Second surface, 40 Connection portion, 41 Plate-shaped solder, 42, 43 Solder layer, 50 Jig, 50a First surface, 50b Second surface, 50c Positioning groove, 51 Base, 60 Heating element, 61 Heating element, 70 Sealing member, 100, 200, 300 Connection structure, DR1 First direction, DR2 Second direction, DR3 Third direction, P pitch, S1 preparation step, S2 positioning step, S3 bonding step, S4 soldering step, S5 peeling step, S6 sealing step, T thickness.

Claims

1. A plurality of insulated wires; A substrate; A plurality of connected parts disposed on the base material; A sealing member is provided, Each of the plurality of insulated wires has a central conductor and an insulating layer covering a peripheral surface of the central conductor, At a tip end portion in an axial direction of each of the plurality of insulated electric wires, the central conductor is exposed from the insulating layer, The plurality of connected portions are arranged in a row, the tip end of each of the plurality of insulated wires is soldered to each of the plurality of connected parts, A connection structure, wherein the sealing member is disposed on the base material so as to cover the tip ends and the connected portions of the plurality of insulated electric wires.

2. Further comprising an adhesive, The connection structure according to claim 1 , wherein the adhesive is applied to a side surface of the tip end of at least one of the plurality of insulated wires.

3. 3. The connection structure according to claim 2, wherein the adhesive is adhered to the tip end of at least one of the plurality of insulated wires up to a portion of the circumferential surface of the tip end that is a distance from an upper end of the tip end that is greater than the smaller of 1 / 10 of an average diameter of the tip end and 3 μm.

4. 3. The connection structure according to claim 2, wherein the adhesive is adhered to the tip end of at least one of the plurality of insulated wires up to a portion of the circumferential surface of the tip end that is a distance from an upper end of the tip end that is greater than the smaller of 1 / 3 of an average diameter of the tip end and 10 μm.

5. The connection structure according to claim 1 , wherein a pitch between two adjacent ones of the plurality of connected parts is 200 μm or less.

6. The connection structure according to claim 1 , wherein the sealing member on the tip portions of the plurality of insulated electric wires has a thickness of 100 μm or less.