JP2014220084A - Branch structure for flat cable, branch flat cable, and method of manufacturing brach flat cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a branch structure for flat cable that can easily and securely connect conductors of crossing flat cables to each other.SOLUTION: There is provided a branch structure for flat cable that is constituted by putting a flat cable body which has first conductors arranged in stripes and a flat cable branch body which has second conductors arranged in stripes one over the other and electrically connects the first conductors and second conductors to each other in an arbitrary combination, and the branch structure for flat cable includes a connection sheet stacked between the first conductors and second conductors arranged opposite each other while having at least opposite surface sides exposed. The connection sheet has a conductive bump arranged for each first intersection part associated with a combination for electric connection between the first and second conductors, a non-conductive bump arranged for each second intersection part except first intersection parts among all intersection parts of the first and second conductors, and an adhesive layer which is laminated in an area other than the conductive bump and non-conductive bump.

Description

  The present invention relates to a flat cable branch structure, a branch flat cable, and a method of manufacturing a branch flat cable.

  Conventionally, a flat cable has been used for electrical connection of electronic components housed in an electronic device. This flat cable is a flexible cable in which a plurality of flat conductors are sandwiched between two insulating films and covered with insulation. However, depending on the design of the electronic device, it is necessary to branch the flat cable at different angles. As a method of branching the flat cable in this way, there is a method of connecting the conductors of the intersecting flat cables using, for example, a substrate such as a flexible printed wiring board or a crimp terminal. However, when the above substrate is used, the procedure for branching the flat cable becomes complicated. In addition, when the above crimp terminal is used, the conductor spacing of the flat cable is limited and the connection reliability is low.

  Therefore, a method of branching the flat cable relatively easily without being limited to the conductor spacing of the flat cable has been proposed (see Japanese Patent Application Laid-Open No. 7-263049). In this method, a connecting body is disposed between intersecting flat cables to connect them. The connection body has an insulating film, an adhesive layer laminated on both sides of the insulating film, and a conductive portion that penetrates the insulating film and the adhesive layer, and intersected by the conductive portion. It is comprised so that the conductors which conduct | electrically_connect a pair of flat cable may be electrically connected.

Japanese Patent Laid-Open No. 7-263049

  The branch structure using the connection body is formed by laminating a pair of flat cables intersecting via the connection body and then crimping them. However, since the adhesive layer of the connection body flows due to the crimping, the thickness of the connection body changes between the location where the conductive portion is provided and the other location (the location where the adhesive layer is laminated). The thickness of the branch structure is not uniform. As a result, stress is applied to the conductors in the branched structure, and the reliability of connection between the conductors may be reduced. In addition, the adhesive strength of the branched structure may be reduced due to the uneven thickness of the connection body.

  The present invention has been made in view of the above disadvantages, and has a flat cable branching structure capable of easily and reliably branching a flat cable, which has excellent adhesive strength and electrical connection reliability, and this branching. An object of the present invention is to provide a branched flat cable having a structure and a method of manufacturing the same.

The invention made to solve the above problems is
A flat cable main body having a plurality of first conductors arranged in a stripe shape and a flat cable branching body having one or a plurality of second conductors arranged in a stripe shape are overlapped so as to cross each other. A flat cable branching structure for conducting one conductor and one or a plurality of second conductors in any combination,
A connection sheet that is disposed between the first conductor and the second conductor that are disposed to face each other and at least the opposite surface side is exposed;
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
And an adhesive layer laminated in a region other than the conductive bump and the non-conductive bump.

Another invention made to solve the above problems is as follows:
A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branched flat cable in which a plurality of first conductors and one or a plurality of second conductors conduct in any combination,
It has a flat cable branching structure at the intersection of the flat cable main body and the flat cable branching body.

Yet another invention made to solve the above problems is as follows:
A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branch flat cable in which a plurality of first conductors and one or a plurality of second conductors are conducted in any combination,
A step of superimposing a connection sheet between the first conductor and the second conductor which are disposed to face each other and at least the opposite surface side is exposed;
Thermocompression bonding the first conductor, the second conductor and the connection sheet,
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
And an adhesive layer laminated in a region other than the conductive bump and the non-conductive bump.

  The flat cable branching structure of the present invention can easily and reliably connect intersecting flat cable conductors, and is excellent in adhesive strength and electrical connection reliability. Moreover, the branched flat cable of this invention is excellent in manufacturability and connection reliability.

FIG. 1 is a schematic sectional view showing a branch structure of a flat cable according to an embodiment of the present invention. FIG. 2 is a schematic plan view of a flat cable main body of the flat cable branching structure of FIG. FIG. 3 is a schematic cross-sectional view taken along line AA in FIG. FIG. 4 is a schematic plan view of a flat cable branch body of the flat cable branch structure of FIG. 1. FIG. 5 is a schematic plan view of a connecting sheet having a flat cable branch structure shown in FIG. 6 is a schematic cross-sectional view taken along line BB in FIG. FIG. 7A is a schematic perspective view showing a method for manufacturing the connection sheet of FIG. 5. FIG. 7B is a schematic perspective view showing a method for manufacturing the connection sheet of FIG. 5. FIG. 7C is a schematic perspective view showing a method for manufacturing the connection sheet of FIG. 5. FIG. 8A is a schematic perspective view showing a method for manufacturing a branched flat cable having the flat cable branch structure of FIG. 1. FIG. 8B is a schematic perspective view illustrating a method for manufacturing a branched flat cable having the flat cable branch structure of FIG. 1. FIG. 8C is a schematic perspective view illustrating a method for manufacturing a branched flat cable having the flat cable branch structure of FIG. 1. FIG. 8D is a schematic perspective view illustrating a method for manufacturing a branched flat cable having the flat cable branch structure of FIG. 1.

[Description of Embodiment of the Present Invention]
The present invention
A flat cable main body having a plurality of first conductors arranged in a stripe shape and a flat cable branching body having one or a plurality of second conductors arranged in a stripe shape are overlapped so as to cross each other. A flat cable branching structure for conducting one conductor and one or a plurality of second conductors in any combination,
A connection sheet that is disposed between the first conductor and the second conductor that are disposed to face each other and at least the opposite surface side is exposed;
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
And an adhesive layer laminated in a region other than the conductive bump and the non-conductive bump.

  The branch structure of the flat cable has conductive bumps at the intersection (first intersection) of the first conductor and the second conductor to be conducted, and the intersection (second second) of the other first conductor and second conductor. A connecting sheet having non-conductive bumps is provided at the intersection). Therefore, the flat cable branching structure can easily connect these conductors by arranging this connection sheet between the first conductor and the second conductor and obtaining a branching structure by pressure bonding. In addition, since bumps are arranged at all the intersections of the first conductor and the second conductor, it is possible to suppress the variation in the thickness of the branch structure and increase the adhesive strength and the connection reliability. Furthermore, since the arrangement of the conductive bumps and non-conductive bumps of the connection sheet can be appropriately changed, the number of first conductors and second conductors, the combination of conductors to be conducted, the crossing angle, etc. can be easily changed. Is possible. Therefore, the flat cable branching structure can branch the flat cable by easily and reliably connecting the first conductor of the flat cable body and the second conductor of the flat cable branching body.

  It is preferable that the conductive bump and the non-conductive bump protrude from one surface of the adhesive layer. By making the conductive bumps and non-conductive bumps protrude from one surface of the adhesive layer in this way, the adhesive enters between the conductor and the conductive bumps while suppressing variations in the thickness of the branch structure. The first conductor and the second conductor can be more reliably electrically connected by preventing the indentation.

  The average protruding height from one surface of the adhesive layer of the conductive bump and the nonconductive bump is preferably 1 μm or more and 15 μm or less. Thus, by setting the average protrusion height from one surface of the adhesive layer of the conductive bump and the non-conductive bump within the above range, the flat cable is formed by the adhesive around the conductive bump and the non-conductive bump. While maintaining the adhesive strength between the main body and the flat cable branch body, the electrical connection between the conductors can be made easier and more reliable by the conductive bumps.

  It is preferable that at least one surface of the connection sheet is flat. In this way, for example, by making the bottom surfaces of the conductive bumps and the non-conductive bumps flush with one surface of the adhesive layer (flat) so that one surface of the connection sheet is flat, In addition to facilitating positioning when laminating the first conductor or the second conductor, one surface of the adhesive layer can be more reliably bonded to the flat cable body or the flat cable branch body, The adhesive strength of the branched structure can be further increased.

  The conductive bumps may be formed by printing a conductive paste. By forming the conductive bumps by printing the conductive paste in this way, the conductive bumps can be easily and reliably disposed at the first intersection.

  The non-conductive bumps may be disposed at each of one or a plurality of second intersecting portions. By arranging the non-conductive bumps at the second intersections in this way, it is possible to increase the plane area of the adhesive layer while suppressing variations in the thickness of the branch structure. The adhesive strength can be further increased.

  It is preferable that one or a plurality of second conductors of the flat cable branching body are exposed on both sides at the intersection, and a protective film is coated on the outer surface side of the second conductor via an adhesive layer. Thus, by covering the protective film from the outer surface side (the other surface side of the second conductor) of the flat cable branch body, it becomes easy to form the branch structure of the flat cable, and the adhesion laminated on the protective film The adhesive strength of the branched structure can be further increased by the agent layer.

Another aspect of the present invention is:
A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branched flat cable in which a plurality of first conductors and one or a plurality of second conductors conduct in any combination,
It has a flat cable branching structure at the intersection of the flat cable main body and the flat cable branching body.

  Since the said branch flat cable has the branch structure of the said flat cable, the 1st conductor of a flat cable main body and the 2nd conductor of a flat cable branch body are connected easily and reliably via the said connection sheet. Therefore, the branch flat cable is excellent in manufacturability and reliability.

Furthermore, another aspect of the present invention provides
A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branch flat cable in which a plurality of first conductors and one or a plurality of second conductors are conducted in any combination,
A step of superimposing a connection sheet between the first conductor and the second conductor which are disposed to face each other and at least the opposite surface side is exposed;
Thermocompression bonding the first conductor, the second conductor and the connection sheet,
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
And an adhesive layer laminated in a region other than the conductive bump and the non-conductive bump.

  The branch flat cable manufacturing method can easily and reliably obtain a branch flat cable in which the first conductor of the flat cable main body and the second conductor of the flat cable branch body are electrically connected.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of a flat cable branch structure according to the present invention will be described in detail with reference to the drawings.

  The flat cable branching structure 1 of FIG. 1 includes a flat cable body 2 having a plurality of first conductors 2a arranged in a stripe shape shown in FIGS. 2 and 3, and a plurality of stripe cables shown in FIG. The flat cable branch body 3 having the second conductor 3a is overlapped so as to intersect at a substantially right angle, and the plurality of first conductors 2a and the plurality of second conductors 3a are electrically connected in any combination. The flat cable branching structure 1 includes a connection sheet 4 laminated between the first conductor 2a and the second conductor 3a arranged to face each other as shown in FIGS. 5 and 6, and a protective film on the outer surface side of the second conductor 3a. The protective film 5 is covered via the adhesive layer 5a.

<Flat cable body>
The flat cable body 2 has a plurality of first conductors 2a arranged in a stripe shape, and an insulating film 2b laminated on the front and back surfaces of the first conductor 2a via a flat cable adhesive layer 2c.

  The 1st conductor 2a is a flat conductor arrange | positioned at stripe form, and is laminated | stacked through the flat cable adhesive layer 2c on the insulating film 2b. The first conductor 2a can be formed of a conductive material, but is generally formed of copper, for example.

  The first conductor 2a is plated on the surface, and a plated layer (not shown) is laminated on the surface. As this plating treatment, tin plating or silver plating is preferable. It is possible to prevent the first conductor 2a exposed during the branching operation from being damaged by the plating process.

  The lower limit of the average thickness (including the plating layer) of the first conductor 2a is preferably 10 μm, and more preferably 25 μm. When the average thickness of the 1st conductor 2a is less than the said minimum, there exists a possibility that electroconductivity may become inadequate. On the other hand, the upper limit of the average thickness (excluding plating) of the first conductor 2a is preferably 100 μm, and more preferably 50 μm. When the average thickness of the first conductor 2a exceeds the upper limit, the flat cable branch structure 1 may be unnecessarily thick.

  The lower limit of the average width (including the plating layer) of the first conductor 2a is preferably 0.1 mm, and more preferably 0.2 mm. When the average width of the first conductor 2a is less than the above lower limit, the conductivity may be insufficient. On the other hand, the upper limit of the average width of the first conductor 2a is preferably 1 mm, and more preferably 0.4 mm. When the average width of the 1st conductor 2a exceeds the said upper limit, there exists a possibility that the width | variety of the said flat cable branch structure 1 may become large unnecessarily.

  As a minimum of the average space | interval (pitch) of the said 1st conductor 2a, 0.2 mm is preferable and 0.3 mm is more preferable. When the average interval between the first conductors 2a is less than the lower limit, adjacent first conductors 2a may come into contact with each other. On the other hand, the upper limit of the average interval between the first conductors 2a is preferably 1.2 mm, and more preferably 1.0 mm. When the average interval between the first conductors 2a exceeds the upper limit, the width of the flat cable branch structure 1 may become unnecessarily large.

  The insulating film 2b is composed of a sheet-like member having flexibility and electrical insulation. Specifically, a resin film can be employed as the insulating film 2b. As a material of this resin film, for example, a polyimide resin, a polyethylene terephthalate resin, or the like is preferably used.

  As a minimum of the softening temperature of insulating film 2b, 100 ° C is preferred, 110 ° C is more preferred, and 120 ° C is still more preferred. When the softening temperature of the insulating film 2b is less than the lower limit, the insulating film 2b may be softened and deformed when the flat cable branch structure 1 is thermocompression bonded. On the other hand, although it does not specifically limit as an upper limit of the softening temperature of the insulating film 2b, For example, it can be 200 degreeC. In addition, a softening temperature means the softening temperature measured based on JISK7196 (1991).

  As a minimum of the glass transition temperature of insulating film 2b, 50 ° C is preferred, 60 ° C is more preferred, and 65 ° C is still more preferred. When the glass transition temperature of the insulating film 2b is less than the lower limit, the strength of the insulating film 2b after the thermocompression bonding of the flat cable branch structure 1 may be insufficient. On the other hand, although it does not specifically limit as an upper limit of the glass transition temperature of the insulating film 2b, For example, it can be 200 degreeC. The glass transition temperature means a midpoint glass transition temperature measured in accordance with JIS K7121 (1987).

  As a minimum of average thickness of insulating film 2b, 5 micrometers is preferred and 10 micrometers is more preferred. When the average thickness of the insulating film 2b is less than the above lower limit, the strength of the insulating film 2b may be insufficient. On the other hand, the upper limit of the average thickness of the insulating film 2b is preferably 40 μm, and more preferably 20 μm. When the average thickness of the insulating film 2b exceeds the upper limit, the flat cable branch structure 1 may be unnecessarily thick.

  Although it does not specifically limit as an adhesive agent which comprises the said flat cable adhesive bond layer 2c, The thing excellent in the softness | flexibility and heat resistance is preferable, As such an adhesive agent, for example, an epoxy resin, a polyimide resin, polyester Various resin-based adhesives such as resin, phenol resin, polyurethane resin, acrylic resin, melamine resin, polyamideimide resin, and the like can be given. Among these, those which are thermoplastic and have a softening temperature and a glass transition temperature lower than those of the non-conductive bumps 4b of the connection sheet 4 described later are preferable.

  As a minimum of the softening temperature of flat cable adhesive layer 2c, 80 ° C is preferred, 90 ° C is more preferred, and 100 ° C is still more preferred. When the softening temperature of the flat cable adhesive layer 2c is less than the lower limit, the flat cable body 2 may be softened and deformed when the flat cable branch structure 1 is thermocompression bonded. On the other hand, the upper limit of the softening temperature of the flat cable adhesive layer 2c is not particularly limited, but may be 200 ° C., for example.

  As a minimum of the glass transition temperature of flat cable adhesive layer 2c, 50 ° C is preferred, 60 ° C is more preferred, and 70 ° C is still more preferred. When the glass transition temperature of the flat cable adhesive layer 2c is less than the above lower limit, the strength of the flat cable branch structure 1 after thermocompression bonding may be insufficient. On the other hand, the upper limit of the glass transition temperature of the flat cable adhesive layer 2c is not particularly limited, but may be 200 ° C., for example.

  The lower limit of the average thickness of the flat cable adhesive layer 2c (the average distance between the insulating film 2b and the first conductor 2a) is preferably 5 μm, and more preferably 15 μm. When the average thickness of the flat cable adhesive layer 2c is less than the above lower limit, the adhesive strength between the insulating film 2b and the first conductor 2a may be insufficient. On the other hand, the upper limit of the average thickness of the flat cable adhesive layer 2c is preferably 50 μm, and more preferably 40 μm. When the average thickness of the flat cable adhesive layer 2c exceeds the upper limit, the flat cable branch structure 1 may be unnecessarily thick.

  The flat cable main body 2 has a surface-side (overlapping direction side) insulating film 2b and adhesive in an area where the flat cable branch 3 intersects and overlaps (hereinafter, may be referred to as an overlapping area). The surface side (surface side) facing the second conductor 3a of the first conductor 2a is exposed. A connection sheet 4 to be described later is laminated on the surface of the overlapping region where the first conductor 2a is exposed, and the second conductor 3a and the protective film 5 of the flat cable branch body 3 are further laminated on the surface side.

<Flat cable branch>
The flat cable branch 3 has a plurality of second conductors 3a arranged in a stripe shape, and an insulating film 3b laminated on the front and back surfaces of the second conductor 3a with a flat cable adhesive layer interposed therebetween. The second conductor 3a, the insulating film 3b, and the flat cable adhesive layer can be the same as the first conductor 2a, the insulating film 2b, and the flat cable adhesive layer 2c of the flat cable body 2, respectively.

  The flat cable branch 3 does not have the front and back insulating films 3b and the adhesive at one end in the longitudinal direction, and both surfaces of the second conductor 3a are exposed. The exposed second conductor 3a is laminated on the surface of the connection sheet 4 laminated on the surface of the overlapping region. Specifically, the plurality of second conductors 3a are stacked so as to intersect the plurality of first conductors 2a substantially at right angles via the connection sheet 4, respectively.

<Connection sheet>
The connection sheet 4 includes a conductive bump 4a disposed at each of a plurality of first intersecting portions related to a combination of conducting the plurality of first conductors 2a and a plurality of second conductors 3a, and a plurality of first conductors 2a and Non-conductive bumps 4b disposed at a plurality of second crossing portions excluding the first crossing portion among all crossing portions of the plurality of second conductors 3a, and other than the conductive bumps 4a and non-conductive bumps 4b And a connection sheet adhesive layer 4c laminated in the region. That is, the connection sheet 4 includes a plurality of conductive bumps 4a and a plurality of nonconductive bumps 4b arranged in a lattice point, and a connection laminated in a region other than the conductive bumps 4a and the nonconductive bumps 4b. And a sheet adhesive layer 4c.

  The arrangement of the bumps will be specifically described with reference to FIGS. The first conductor 2a of the flat cable body 2 is defined as conductors P1, P2, and P3 from above in the figure, and the second conductor 3a of the flat cable branch 3 is defined as conductors Q1, Q2, and Q3 from the left in the figure. Moreover, let the area | region where the nth conductor Pn of the flat cable main body 2 and the mth conductor Qm of the flat cable branch body 3 cross | intersect on the surface of the connection sheet 4 be crossing part Rnm. For example, the region where the conductor P1 and the conductor Q3 intersect is the intersection R13.

  The flat cable branch structure 1 is a combination in which the conductor P1 and the conductor Q1, the conductor P2 and the conductor Q2, the conductor P3 and the conductor Q3 are electrically connected. That is, the conductor P1 is branched in the crossing direction by the conductor Q1, the conductor P2 is branched by the conductor Q2, and the conductor P3 is branched by the conductor Q3. Intersections R11, R22, R33 at which the conductors of the conductive combination intersect are the first intersections, and conductive bumps 4a are arranged one-on-one at these intersections. Intersections R12, R13, R21, R23, R31, and R32 other than the first intersection are second intersections, and non-conductive bumps 4b are respectively arranged on a one-to-one basis at these intersections. .

  The combination of the first conductor 2a and the second conductor 3a to be conducted can be arbitrarily selected. For example, the conductor P1 and the conductor Q2, the conductor P2 and the conductor Q3, and the conductor P3 and the conductor Q1 are brought into conduction. You can also. In this case, the intersections R12, R23, R31 are the first intersections, and the conductive bumps 4a are disposed at these intersections, and the non-conductive bumps 4b are disposed at the other intersections.

  The conductive bumps 4a and the non-conductive bumps 4b protrude from the surface of the connection sheet adhesive layer 4c as shown in FIG. The bottom surfaces of the conductive bumps 4a and the non-conductive bumps 4b are flush with the back surface of the connection sheet adhesive layer 4c so that the back surface of the connection sheet 4 is flat. Furthermore, it is preferable that the surface side of the conductive bump 4a has a convex shape as shown in FIG. Thus, by making the conductive bump 4a into a convex shape, the contact pressure to the second conductor 3a can be increased, and the second conductor 3a and the conductive bump 4a can be more reliably conducted.

  Further, the planar shapes of the conductive bumps 4a and the non-conductive bumps 4b are not particularly limited, and may be any shape such as a circle or a rectangle. However, the first conductor 2a and the second conductor 3a intersecting with each other Considering the connectivity, a shape such as a circle having isotropic properties is preferable.

  The material of the conductive bump 4a is not particularly limited as long as it has conductivity, but a conductive paste can be suitably used. By using the conductive paste, the conductive bump 4a can be easily and reliably formed at an arbitrary position of the connection sheet 4, and the convex conductive bump 4a can be formed.

  As the conductive paste, a paste in which conductive particles such as metal particles are dispersed in a binder can be used.

  As said metal particle, silver, platinum, gold | metal | money, copper, nickel, palladium, solder etc. can be mentioned, for example, These can be used individually or in mixture of 2 or more types. Among these, silver powder, silver-coated copper powder, solder powder and the like exhibiting excellent conductivity are preferable. As a conductive paste using silver powder, for example, a conductive paste disclosed in JP 2007-66824 A can be suitably used.

  As a minimum of the content rate of the electroconductive particle of the electroconductive paste which forms the electroconductive bump 4a, 40 volume% is preferable and 45 volume% is more preferable. When the content rate of electroconductive particle is less than the said minimum, there exists a possibility that the electrical connectivity between conductors may fall. On the other hand, the upper limit of the conductive particle content of the conductive paste forming the conductive bump 4a is preferably 95% by volume, more preferably 85% by volume. When the content rate of the electroconductive particle of an electroconductive paste exceeds the said upper limit, the fluidity | liquidity of an electroconductive paste falls and there exists a possibility that formation of the electroconductive bump 4a may become difficult.

  Examples of the binder include an epoxy resin, a phenol resin, a polyester resin, a polyurethane resin, an acrylic resin, a melamine resin, a polyimide resin, a polyamideimide resin, and the like, and one or more of these are used. Can do. Among these, a thermosetting resin that can improve the heat resistance of the conductive paste is preferable, and an epoxy resin is particularly preferable.

  Examples of the epoxy resin used in the conductive paste include bisphenol A type, F type, S type, AD type, copolymer type of bisphenol A type and bisphenol F type, naphthalene type, novolac type, biphenyl type, dicyclopentadiene type. And phenoxy resin which is a polymer epoxy resin.

  The binder can be used by dissolving in a solvent. Examples of the solvent include ester-based, ether-based, ketone-based, ether-ester-based, alcohol-based, hydrocarbon-based, and amine-based organic solvents, and one or more of these are used. be able to. When the conductive bump 4a is formed by printing a conductive paste, it is preferable to use a high boiling point solvent excellent in printability, and specifically, carbitol acetate, butyl carbitol acetate or the like is preferably used.

  Furthermore, a curing agent can be added to the binder. Examples of the curing agent include amine curing agents, polyaminoamide curing agents, acid and acid anhydride curing agents, basic active hydrogen compounds, tertiary aminos, and imidazoles.

  In addition to the components described above, auxiliary agents such as thickeners and leveling agents can be added to the conductive paste. Moreover, an electrically conductive paste can be obtained by mixing said each component, for example with a three roll, a rotary stirring deaerator, etc.

  The lower limit of the average width of the conductive bump 4a is preferably 0.1 mm, and more preferably 0.2 mm. When the average width of the conductive bump 4a is less than the above lower limit, the conductivity between the first conductor 2a and the second conductor 3a may be insufficient. On the other hand, the upper limit of the average width of the conductive bump 4a is preferably 0.5 mm, and more preferably 0.4 mm. When the average width of the conductive bumps 4a exceeds the above upper limit, the flat cable branching structure 1 may be caused by fear that the conductive bumps 4a may come into contact with other conductors that are not conductive or the planar area of the connection sheet adhesive layer 4c is reduced. Adhesive strength may be insufficient. The average width of the conductive bumps 4a means the average of the diameters of circles passing through the center of the conductive bumps 4a in the height direction and inscribed in a cross section parallel to the connection sheet 4. The average width of the conductive bump 4a is preferably substantially the same as the average width of the first conductor 2a and the second conductor 3a. That is, the average width of the conductive bumps 4a is preferably 80% to 120% of the average width of the first conductor 2a and the second conductor 3a.

  The lower limit of the average height of the conductive bump 4a is preferably 5 μm, and more preferably 15 μm. When the average height of the conductive bumps 4a is less than the above lower limit, the conductivity with the first conductor 2a and the second conductor 3a may be insufficient. On the other hand, the upper limit of the average height of the conductive bumps 4a is preferably 50 μm, and more preferably 40 μm. When the average height of the conductive bump 4a exceeds the upper limit, the flat cable branch structure 1 may be unnecessarily thick. In addition, the average height of the conductive bump 4a means the average of the maximum height of the conductive bump 4a.

  The lower limit of the average protrusion height from the surface of the connection sheet adhesive layer 4c of the conductive bump 4a is preferably 1 μm, and more preferably 8 μm. When the average protrusion height of the conductive bump 4a from the surface of the connection sheet adhesive layer 4c is less than the lower limit, an adhesive enters between the conductive bump 4a and the second conductor 3a, and the first conductor 2a and the second conductor 2a. There is a possibility that the conductivity with the conductor 3a may be insufficient. On the other hand, the upper limit of the average protrusion height of the conductive bump 4a from the surface of the connection sheet adhesive layer 4c is preferably 15 μm, and more preferably 12 μm. When the average protrusion height from the surface of the connection sheet adhesive layer 4c of the conductive bump 4a exceeds the above upper limit, the adhesive around the conductive bump 4a is not sufficiently filled, and the adhesive strength of the flat cable branch structure 1 May become insufficient. The average protruding height of the conductive bump 4a from the surface of the connection sheet adhesive layer 4c is obtained by subtracting the average thickness of the connection sheet adhesive layer 4c from the average height of the conductive bump 4a.

  As the material of the non-conductive bump 4b, it is preferable to use a resin having a softening temperature and a glass transition temperature higher than that of the connection sheet adhesive layer 4c in addition to high insulation. Specific examples include thermoplastic resins such as polyester resins, polyamide resins, acrylic resins, polyacetal resins, and phenoxy resins. A thermosetting adhesive such as epoxy can also be used.

  The lower limit of the softening temperature of the non-conductive bump 4b is preferably 80 ° C, more preferably 110 ° C, and further preferably 120 ° C. When the softening temperature of the nonconductive bump 4b is less than the lower limit, the nonconductive bump 4b may be softened and deformed when the flat cable branch structure 1 is thermocompression bonded. On the other hand, the upper limit of the softening temperature of the non-conductive bump 4b is not particularly limited, but may be 200 ° C., for example.

  As a minimum of the glass transition temperature of nonelectroconductive bump 4b, 70 ° C is preferred, 75 ° C is more preferred, and 80 ° C is still more preferred. When the glass transition temperature of the nonconductive bump 4b is less than the lower limit, the strength of the nonconductive bump 4b after the thermocompression bonding of the flat cable branch structure 1 may be insufficient. On the other hand, the upper limit of the glass transition temperature of the non-conductive bump 4b is not particularly limited, but may be 200 ° C., for example.

  It is preferable to add a curing agent to the resin constituting the non-conductive bump 4b in order to increase the softening temperature. As this curing agent, for example, an isocyanate curing agent can be used.

  Although the formation method of the nonelectroconductive bump 4b is not specifically limited, For example, the method of dissolving and printing the said resin in a solvent can be used. As this solvent, those having a high boiling point are preferable so as not to cause clogging during printing. For example, isophorone, benzyl alcohol, butyl carbitol acetate, cyclohexane and the like can be used.

  The lower limit of the average width of the non-conductive bump 4b is preferably 0.1 mm, and more preferably 0.2 mm. When the average width of the non-conductive bump 4b is less than the lower limit, there is a possibility that sufficient insulation between the first conductor 2a and the second conductor 3a that are not conductive cannot be ensured. On the other hand, the upper limit of the average width of the non-conductive bump 4b is preferably 0.5 mm, and more preferably 0.4 mm. When the average width of the non-conductive bumps 4b exceeds the above upper limit, the adhesive strength of the flat cable branch structure 1 may be insufficient due to a reduction in the planar area of the connection sheet adhesive layer 4c. The average width of the nonconductive bumps 4ba means the average of the diameters of the circles passing through the center in the height direction of the nonconductive bumps 4b and inscribed in a cross section parallel to the connection sheet 4. Moreover, it is preferable that the average width of the non-conductive bump 4b is substantially the same as the average width of the first conductor 2a and the second conductor 3a, like the conductive bump 4a.

  The average height of the non-conductive bump 4b is preferably substantially the same as that of the conductive bump 4a. That is, the average height of the non-conductive bump 4b is preferably 80% or more and 120% or less of the average height of the conductive bump 4a. When the average height of the non-conductive bump 4b is somewhat larger or smaller than the average height of the conductive bump 4a, the height of the connection sheet 4 differs between the first intersection and the second intersection, and the flat cable branch structure 1 may vary, and unnecessary stress may be applied to the first conductor 2a and the second conductor 3a. However, if the non-conductive bump 4b is higher than the conductive bump 4a, the conductivity of the first conductor 2a and the second conductor 3a may be reduced. Therefore, the average height of the non-conductive bump 4b More preferably, the average height of the bumps 4a is 80% or more and 100% or less.

  The connection sheet adhesive layer 4c is formed of an adhesive that fills the periphery of the conductive bump 4a and the nonconductive bump 4b in plan view. The adhesive is preferably a thermoplastic resin, and examples thereof include a polyamide resin, a polyester resin, an acrylic resin, a melamine resin, a polyamideimide resin, a polyacetal resin, and a phenoxy resin. The adhesive used for the connection sheet adhesive layer 4c is preferably one having a softening temperature and a glass transition temperature lower than those of the non-conductive bump 4b.

  Note that a colorant such as a pigment may be added to the connection sheet adhesive layer 4c so as to improve the visibility during printing and to facilitate alignment with a camera, for example.

  The upper limit of the softening temperature of the connection sheet adhesive layer 4c is preferably 150 ° C, more preferably 140 ° C, and further preferably 130 ° C. When the softening temperature of the connection sheet adhesive layer 4c exceeds the above upper limit, the temperature at the time of thermocompression bonding of the flat cable branch structure 1 needs to be increased, so that productivity may be lowered. On the other hand, as a minimum of the softening temperature of the connection sheet adhesive layer 4c, 50 degreeC is preferable and 60 degreeC is more preferable. When the softening temperature of the connection sheet adhesive layer 4c is less than the above lower limit, the heat resistance (strength maintenance at high temperature) of the flat cable branch structure 1 may be insufficient.

  The upper limit of the glass transition temperature of the connection sheet adhesive layer 4c is preferably 130 ° C, more preferably 120 ° C, and even more preferably 110 ° C. When the glass transition temperature of the connection sheet adhesive layer 4c exceeds the above upper limit, the adhesive strength of the flat cable branch structure 1 may be insufficient. On the other hand, the lower limit of the glass transition temperature of the connection sheet adhesive layer 4c is preferably −20 ° C., more preferably −10 ° C. When the glass transition temperature of the connection sheet adhesive layer 4c is less than the above lower limit, the heat resistance (strength maintenance at high temperature) of the flat cable branch structure 1 may be insufficient.

  The method for forming the connection sheet adhesive layer 4c is not particularly limited, and for example, a method in which the resin is dissolved in a solvent and printed around the conductive bumps 4a and the non-conductive bumps 4b can be used. As this solvent, those having a high boiling point are preferable so as not to cause clogging during printing. For example, isophorone, benzyl alcohol, butyl carbitol acetate, cyclohexane and the like can be used.

  The upper limit of the average thickness of the connection sheet adhesive layer 4c is preferably 40 μm, and more preferably 30 μm. When the average thickness of the connection sheet adhesive layer 4c exceeds the above upper limit, the electrical connectivity between conductors due to the conductive bumps 4a may be reduced, and the flat cable branch structure 1 may be unnecessarily thick. On the other hand, the lower limit of the average thickness of the connection sheet adhesive layer 4c is preferably 5 μm and more preferably 10 μm. When the average thickness of the connection sheet adhesive layer 4c is less than the above lower limit, the adhesive strength of the flat cable branch structure 1 may be insufficient.

<Method for manufacturing connection sheet>
The connection sheet 4 can be manufactured, for example, by the following method.

  First, as shown in FIG. 7A, a conductive paste is printed on the surface of the release film X to form a plurality of conductive bumps 4a. The method for printing this conductive paste is not particularly limited, and for example, screen printing, gravure printing, offset printing, flexographic printing, ink jet printing, dispenser printing, and the like can be used. Moreover, it is preferable to dry the conductive paste at a temperature of 70 to 90 ° C. for about 10 to 60 minutes after printing.

  Next, as shown in FIG. 7B, an insulating resin is printed on the surface of the release film X to form a plurality of nonconductive bumps 4b. The printing method of the insulating resin can be the same as the printing method of the conductive paste. Moreover, it is preferable to dry the insulating resin after printing for about 10 to 60 minutes at a temperature of 70 to 90 ° C., for example. Note that the non-conductive bump 4b may be formed before the conductive bump 4a.

  After the formation of the conductive bumps 4a and the non-conductive bumps 4b, the connection sheet adhesive layer 4c is formed by printing an adhesive around the bumps on the surface of the release film X as shown in FIG. 7C. The method for printing the adhesive can be the same as the method for printing the conductive paste. Moreover, after printing an adhesive agent, it is preferable to dry for about 10 to 60 minutes at the temperature of 70-90 degreeC, for example.

  After forming the connection sheet adhesive layer 4c, the connection sheet 4 can be obtained by peeling the release film X. The release film X is not particularly limited as long as it has releasability on the surface. For example, a film obtained by coating a polyethylene terephthalate film with a silicone release agent can be used.

<Protective film>
The protective film 5 is an insulating film laminated on the surface side of the second conductor 3a via the protective film adhesive layer 5a.

  As the material of the protective film 5, the same material as the insulating film 2 b of the flat cable body 2 can be used. Moreover, the average thickness of the protective film 5 can also be made the same as that of the insulating film 2 b of the flat cable body 2.

  The material and average thickness of the protective film adhesive layer 5 a can be the same as those of the flat cable adhesive layer 2 c of the flat cable body 2. The protective film adhesive layer 5a preferably has a softening temperature and a glass transition temperature lower than those of the nonconductive bumps 4b of the connection sheet 4.

  As an upper limit of the softening temperature of the protective film adhesive layer 5a, 150 degreeC is preferable, 140 degreeC is more preferable, and 130 degreeC is further more preferable. When the softening temperature of the protective film adhesive layer 5a exceeds the above upper limit, the temperature at the time of thermocompression bonding of the flat cable branch structure 1 needs to be increased, so that productivity may be lowered. On the other hand, as a minimum of the softening temperature of the protective film adhesive layer 5a, 50 degreeC is preferable and 60 degreeC is more preferable. When the softening temperature of the protective film adhesive layer 5a is less than the above lower limit, the heat resistance (strength maintenance at high temperature) of the flat cable branch structure 1 may be insufficient.

  As an upper limit of the glass transition temperature of the protective film adhesive layer 5a, 130 degreeC is preferable, 120 degreeC is more preferable, and 110 degreeC is further more preferable. When the glass transition temperature of the protective film adhesive layer 5a exceeds the upper limit, the adhesive strength of the flat cable branch structure 1 may be insufficient. On the other hand, the lower limit of the glass transition temperature of the protective film adhesive layer 5a is preferably −20 ° C., and more preferably −10 ° C. When the glass transition temperature of the protective film adhesive layer 5a is less than the above lower limit, the heat resistance (strength maintenance at high temperature) of the flat cable branch structure 1 may be insufficient.

  As an upper limit of the average distance from the surface of the 1st conductor 2a to the back surface of the protective film 5, 100 micrometers is preferable and 80 micrometers is more preferable. When the average distance from the surface of the 1st conductor 2a to the back surface of the protective film 5 exceeds the said upper limit, there exists a possibility that the said flat cable branch structure 1 may become thick unnecessarily. On the other hand, as a minimum of the average distance from the surface of the 1st conductor 2a to the back surface of the protective film 5, 20 micrometers is preferable and 40 micrometers is more preferable. When the average distance from the surface of the first conductor 2a to the back surface of the protective film 5 is less than the lower limit, the adhesive filling amount is small, and thus the adhesive strength of the flat cable branch structure 1 may be insufficient. .

<Advantages>
The flat cable branch structure 1 has conductive bumps 4a at the intersection (first intersection) between the first conductor 2a and the second conductor 3a to be conducted, and the other first conductor 2a and the second conductor that are not conducted. A connection sheet 4 having non-conductive bumps 4b is provided at the intersection 3a (second intersection). Therefore, the flat cable branch structure 1 can easily connect these conductors by arranging the connection sheet 4 between the first conductor 2a and the second conductor 3a and obtaining a branch structure by pressure bonding. Further, since bumps are arranged at all the intersections of the first conductor 2a and the second conductor 3a, the thickness variation of the branch structure is suppressed, and the flat cable branch structure 1 has high adhesive strength and connection reliability. Have

  Moreover, since the said conductive bump 4a and the nonelectroconductive bump 4b protrude from the connection sheet adhesive bond layer 4c surface, the said flat cable branch structure 1 suppresses the thickness variation of a branch structure, and the 1st conductor 2a. And the 2nd conductor 3a can be electrically connected more reliably. Furthermore, since the back surface of the connection sheet 4 is flat, that is, the bottom surfaces of the conductive bumps 4a and the non-conductive bumps 4b are flush with the back surface of the connection sheet adhesive layer 4c, the connection sheet 4 is laminated on the first conductor 2a. In addition to facilitating positioning, the back surface of the connection sheet adhesive layer 4c can be more reliably bonded to the flat cable body 2, so that the adhesive strength can be further increased.

  Furthermore, since the flat cable branch structure 1 has the non-conductive bumps 4b disposed at the second intersections, the planar area of the connection sheet adhesive layer 4c is large and the adhesive strength is excellent.

  Moreover, since the said flat cable branch structure 1 has the protective film 5 coat | covered through the protective film adhesive bond layer 5a on the surface side of the 2nd conductor 3a, it can raise adhesive strength more.

  Note that the flat cable branch structure 1 has the arrangement of the conductive bumps 4a and the non-conductive bumps 4b of the connection sheet 4 even if the number of the first conductors 2a and the second conductors 3a and the combination of the conductors to be changed are changed. It is possible to easily cope with this by appropriately changing the setting.

<Branch flat cable>
In the branch flat cable having the flat cable branch structure 1, the first conductor 2 a of the flat cable body 2 and the second conductor 3 a of the flat cable branch body 3 are connected via a connection sheet 4. That is, the branched flat cable includes a flat cable main body 2 having a plurality of first conductors 2a, a flat cable branching body 3 having a plurality of second conductors 3a, and a first conductor 2a and a second conductor 3a disposed to face each other. The connection sheet 4 laminated | stacked in between and the protective film 5 which coat | covers the outer surface side of the 2nd conductor 3a are provided. Therefore, the branch flat cable is excellent in manufacturability and reliability.

<Manufacturing method of branch flat cable>
The branched flat cable can be easily and reliably manufactured by a manufacturing method having the following steps.
(1) The process of exposing the opposing surface side with the 2nd conductor 3a of the 1st conductor 2a of the flat cable main body 2 (2) The process of exposing the both surfaces side of the edge part of the 2nd conductor 3a of the flat cable branch body 3 ( 3) Step of superimposing the connection sheet 4 between the first conductor 2a and the second conductor 3a (4) Step of laminating the protective film 5 on the opposite side of the opposing surface of the second conductor 3a (5) First conductor 2a, second Step of thermocompression bonding the two conductors 3a, the connection sheet 4 and the protective film 5

<(1) First conductor exposure step>
In the first conductor exposing step, as shown in FIG. 8A, the insulating film 2 b on the surface side (overlapping direction side) of the insulating film 2 b on the surface side (overlapping direction side) is overlapped and overlapped with the flat cable branch 3 of the flat cable body 2. It peels and the adhesive agent of the surface side of the 1st conductor 2a is removed. Thereby, the opposing surface side with the 2nd conductor 3a of the 1st conductor 2a is exposed.

<(2) Second conductor exposure step>
In the second conductor exposing step, the insulating film 3b on the front surface and the back surface side is peeled off at one end in the longitudinal direction of the flat cable branch body 3, and the adhesive on the front surface and the back surface side of the second conductor 3a is further removed. This exposes both sides of the second conductor 3a. In addition, you may coat | cover an insulating film previously so that the conductor of an edge part may be exposed at the time of manufacture of the flat cable branch body 3. FIG.

<(3) Superposition process>
In the superimposing step, the connection sheet 4 is laminated on the exposed surface of the first conductor 2a as shown in FIG. 8B, and the second conductor 3a of the flat cable branch body 3 is further laminated on the surface as shown in FIG. 8C. The connection sheet 4 is overlapped between these conductors. At this time, adjustment is made so that the conductive bumps 4a or the non-conductive bumps 4b are located at each intersection where the first conductor 2a and the second conductor 3a intersect.

<(4) Protective film lamination process>
In the protective film laminating step, as shown in FIG. 8D, the protective film 5 having the protective film adhesive layer 5a laminated on the back surface is laminated on the opposite side (front surface side) of the second conductor 3a.

  The upper limit of the average thickness of the protective film adhesive layer 5a before thermocompression bonding is preferably 50 μm, and more preferably 40 μm. When the average thickness of the protective film adhesive layer 5a before thermocompression bonding exceeds the above upper limit, the adhesive may enter between the first conductor 2a and the conductive bump 4a, and the connectivity may be reduced. There is a possibility that the branch structure portion of the flat cable becomes unnecessarily thick. On the other hand, the lower limit of the average thickness of the protective film adhesive layer 5a before thermocompression bonding is preferably 10 μm, and more preferably 20 μm. When the average thickness of the protective film adhesive layer 5a before thermocompression bonding is less than the above lower limit, the remaining amount of indentation at the time of thermocompression bonding is insufficient. There is a possibility that the adhesive strength of the branch structure portion of the branch flat cable may be insufficient because the adhesive is not filled around.

<(5) Thermocompression bonding process>
In the thermocompression bonding step, the laminated body of the first conductor 2a, the second conductor 3a, the connection sheet 4 and the protective film 5 is thermocompression bonded. Specifically, a cushioning material is placed on the surface of the laminated protective film 5 and then thermocompression bonded with a heat tool. The buffer material is preferably made of a material that does not adhere to the adhesive that leaks from the end of the laminate during thermocompression bonding. For example, a polytetrafluoroethylene sheet can be used.

  The heating temperature in the thermocompression bonding step is not higher than the softening temperature of the non-conductive bump 4b, the insulating film of the flat cable body 2 and the flat cable branch body 3, and the protective film 5, and the connection sheet adhesive layer of the connection sheet 4. 4c, the glass transition temperature of the flat cable adhesive layer 2c of the flat cable body 2 and the protective film adhesive layer 5a is preferably higher than the glass transition temperature, and the non-conductive bump 4b, the flat cable body 2 and the flat cable branch 3 Below the glass transition temperature of the insulating film and the protective film 5 and above the softening temperature of the connecting sheet adhesive layer 4c of the connecting sheet 4, the flat cable adhesive layer 2c of the flat cable body 2, and the protective film adhesive layer 5a. It is more preferable. By setting the heating temperature in this manner, each adhesive can be softened and each member can be securely bonded while suppressing deformation of each insulating film and non-conductive bump 4b. As a specific heating temperature in the thermocompression bonding step, it can be set to, for example, 50 ° C. or more and 200 ° C. or less.

  As a pressurization load in the above-mentioned thermocompression bonding process, it can be 0.5 MPa or more and 5 MPa or less, for example. Moreover, as pressurization time, it can be set as 1 second or more and 30 seconds or less, for example.

  In addition, in the branch structure of the flat cable formed by the manufacturing method of the branch flat cable, the region that is formed at the end of the branch structure and the protective film 5 does not face the insulating film of the flat cable body 2 or the flat cable branch body 3 (A region where an insulating film is laminated only on one side) is easily bent by an external force. Therefore, it is preferable to cover the branch structure with a reinforcing tape including this portion after the thermocompression bonding step. As this reinforcing tape, for example, a polyethylene terephthalate film coated with an adhesive can be used.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  In the above-described embodiment, the flat cable main body and the flat cable branching body are overlapped so as to intersect at a substantially right angle. However, the flat cable main body and the flat cable branching body can be crossed at other angles. Also in this case, the flat cable branching structure is formed by forming conductive bumps and non-conductive bumps at the intersections of the first conductor and the second conductor formed by the intersection of the flat cable main body and the flat cable branching body. Can be obtained.

  Further, a flat cable branch having a smaller number of conductors than the flat cable main body may be connected to the flat cable main body, and the flat cable branch may have one conductor.

  Furthermore, in the above-described embodiment, the connection sheet is disposed so that the conductive bumps and non-conductive bumps of the connection sheet are in contact with the second conductor and the flat surface is laminated on the first conductor. You may arrange | position a connection sheet so that the side from which the electroconductive bump and the nonelectroconductive bump protruded may contact | abut to a 1st conductor. However, in order to stably arrange the connection sheet, it is preferable to arrange the connection sheet so that the flat surface is laminated on the first conductor.

  Further, in the connection sheet, the conductive bump and the non-conductive bump do not necessarily protrude from the front surface or the back surface of the adhesive layer, and may protrude from both the front surface and the back surface of the adhesive layer. However, in order to ensure the flatness of the branch structure, it is preferable that the protruding heights of the conductive bump and the non-conductive bump are substantially the same.

  Furthermore, in the said embodiment, although the nonelectroconductive bump was provided for every 2nd cross | intersection part, you may provide the rod-shaped or plate-shaped nonelectroconductive bump which straddles a some 2nd cross | intersection part.

  Further, the protective film may be laminated on the second conductor before the second conductor is laminated on the connection sheet. Furthermore, it is also possible to omit the lamination of the protective film while leaving the insulating film on the surface side of the flat cable branch (on the side opposite to the surface facing the flat cable body).

  The plating on the first conductor and the second conductor is not essential, and a conductor having no plating layer may be used.

  The flat cable branch structure of the present invention can easily and reliably connect the conductors of intersecting flat cables. Moreover, the branched flat cable of this invention is excellent in manufacturability and connection reliability.

DESCRIPTION OF SYMBOLS 1 Flat cable branch structure 2 Flat cable main body 2a 1st conductor 2b Insulating film 2c Flat cable adhesive layer 3 Flat cable branch 3a 2nd conductor 3b Insulating film 4 Connection sheet 4a Conductive bump 4b Nonconductive bump 4c Connection sheet adhesion Agent layer 5 protective film 5a protective film adhesive layer

Claims (9)

A flat cable main body having a plurality of first conductors arranged in a stripe shape and a flat cable branching body having one or a plurality of second conductors arranged in a stripe shape are overlapped so as to cross each other. A flat cable branching structure for conducting one conductor and one or a plurality of second conductors in any combination,
A connection sheet that is disposed between the first conductor and the second conductor that are disposed to face each other and at least the opposite surface side is exposed;
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
A flat cable branching structure comprising: an adhesive layer laminated in a region other than the conductive bump and the nonconductive bump.   The branched structure of the flat cable according to claim 1, wherein the conductive bump and the nonconductive bump protrude from one surface of the adhesive layer.   The branch structure of a flat cable according to claim 2, wherein an average protrusion height from one surface of the adhesive layer of the conductive bump and the nonconductive bump is 1 µm or more and 15 µm or less.   The at least one surface of the said connection sheet is flat, The branch structure of the flat cable of Claim 1, Claim 2 or Claim 3.   The branched structure of the flat cable according to any one of claims 1 to 4, wherein the conductive bump is formed by printing a conductive paste.   The flat cable branching structure according to any one of claims 1 to 5, wherein the non-conductive bump is disposed at each of one or a plurality of second intersecting portions. One or more second conductors of the flat cable branch body are exposed on both sides at the intersection,
The flat cable branch structure according to any one of claims 1 to 6, wherein a protective film is coated on an outer surface side of the second conductor via an adhesive layer. A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branched flat cable in which a plurality of first conductors and one or a plurality of second conductors conduct in any combination,
A branched flat cable comprising the flat cable branching structure according to any one of claims 1 to 7 at an intersection between the flat cable main body and the flat cable branching body. A flat cable branch having a plurality of first conductors arranged in a stripe shape and one or a plurality of second conductors arranged in a stripe shape and superimposed so as to intersect the flat cable body A branch flat cable in which a plurality of first conductors and one or a plurality of second conductors are conducted in any combination,
A step of superimposing a connection sheet between the first conductor and the second conductor which are disposed to face each other and at least the opposite surface side is exposed;
Thermocompression bonding the first conductor, the second conductor and the connection sheet,
This connection sheet
A conductive bump disposed at each of one or a plurality of first intersecting portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors;
Non-conductive bumps disposed at one or a plurality of second intersecting portions excluding the first intersecting portion among all the intersecting portions of the plurality of first conductors and the one or more second conductors;
A method for producing a branched flat cable, comprising: an adhesive layer laminated in a region other than the conductive bump and the nonconductive bump.

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