JP2015149206A - Connection sheet for branching flat cable and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection sheet for branching a flat cable that is excellent in reliability of adhesive strength and electrical connection and can easily and surely connect intersecting conductors of a flat cable to each other.SOLUTION: In the connection sheet for branching a flat cable, in a state where a flat cable body having a plurality of first conductors arranged in a stripe shape and a flat cable branch body having one or more second conductors arranged in a stripe shape overlap with each other so as to intersect with each other, the plurality of first conductors and the one or more second conductors are electrically conducted to each other in arbitrary combination thereof. The connection sheet comprises one or more solder paste bodies containing a low melting point metal and arranged for each of one or more intersection planned parts associated with the combination for electrical conduction of the plurality of first conductors and the one or more second conductors, and a substrate layer laminated on an area other than the solder paste bodies and including an adhesive layer and an insulating resin layer. The softening temperature of the insulating resin layer is higher than that of the adhesive layer.

Description

  The present invention relates to a flat cable branch connection sheet and a method of manufacturing the same.

  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 strip-shaped 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 branching 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 thermocompression bonding them. However, depending on the thermocompression bonding conditions, not only the adhesive layer of the connector but also the insulating film is softened. Therefore, the conductors that should not be conducted due to the softening of the insulating film approach each other, and noise or the like may be easily generated. In addition, the thickness of the branched structure becomes non-uniform, and the adhesive strength of the branched structure may be reduced.

  The present invention has been made in view of the above disadvantages, and is a flat cable branch that is excellent in adhesive strength and electrical connection reliability, and can easily and reliably connect crossing flat cable conductors. An object is to provide a connection sheet.

  The invention made in order to solve the above-described problems includes a flat cable body having a plurality of first conductors arranged in a stripe shape and a flat cable branch having one or a plurality of second conductors arranged in a stripe shape. A flat cable branching connection sheet for conducting a plurality of first conductors and one or a plurality of second conductors in an arbitrary combination in a state of being overlapped so as to cross the body, the plurality of first conductors and One or a plurality of solder paste bodies containing a low melting point metal and disposed in a region other than the solder paste body, arranged at each of one or a plurality of planned intersections related to a combination for conducting a plurality of second conductors And a base material layer including an adhesive layer and an insulating resin layer, and the softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer.

  Another invention made to solve the above-mentioned problems is a flat cable body having a plurality of first conductors arranged in a stripe shape and a flat having one or more second conductors arranged in a stripe shape. A method for manufacturing a flat cable branch connection sheet in which a plurality of first conductors and one or a plurality of second conductors are electrically connected in an arbitrary combination in a state where the cable branch bodies are overlapped so as to intersect with each other. A step of laminating an insulating resin layer on one surface of the adhesive layer, and one or a plurality of crossing-scheduled portions related to a combination of conducting a plurality of first conductors and one or a plurality of second conductors in the adhesive layer and the insulating resin layer. A step of forming a through hole; and a step of printing a solder paste containing a metal having a low melting point in the through hole. The softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer.

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

FIG. 1 is a schematic plan view of a flat cable branching connection sheet according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. FIG. 3A is a schematic perspective view illustrating a manufacturing method of the flat cable branch connection sheet of FIG. 1. FIG. 3B is a schematic perspective view showing a method for manufacturing the flat cable branching connection sheet of FIG. 1. FIG. 3C is a schematic perspective view illustrating a manufacturing method of the flat cable branch connection sheet of FIG. 1. FIG. 4 is a schematic cross-sectional view showing a flat cable branch structure using the flat cable branch connection sheet of FIG. 1. FIG. 5 is a schematic plan view of the flat cable main body of the flat cable branching structure of FIG. 6 is a schematic cross-sectional view taken along line BB in FIG. FIG. 7 is a schematic plan view of a flat cable branch body of the flat cable branch structure of FIG. FIG. 8 is a schematic end view taken along the line CC of FIG. FIG. 9A is a schematic cross-sectional view illustrating a method of forming a convex portion of the second conductor of the flat cable branching body of FIG. FIG. 9B is a schematic cross-sectional view showing a method for forming the convex portion of the second conductor of the flat cable branch of FIG. FIG. 9C is a schematic cross-sectional view showing a method for forming the convex portion of the second conductor of the flat cable branching body of FIG. 7. FIG. 10A is a schematic perspective view showing a manufacturing method of the flat cable branching structure of FIG. FIG. 10B is a schematic perspective view showing a method for manufacturing the flat cable branching structure of FIG. 4. FIG. 10C is a schematic perspective view showing a method for manufacturing the flat cable branching structure of FIG. FIG. 10D is a schematic perspective view illustrating a method for manufacturing the flat cable branching structure of FIG. 4.

[Description of Embodiment of the Present Invention]
The present invention superimposes a flat cable body having a plurality of first conductors arranged in a stripe shape and a flat cable branch having one or more second conductors arranged in a stripe shape so as to intersect each other. A flat cable branch connection sheet for conducting a plurality of first conductors and one or a plurality of second conductors in an arbitrary combination in a state where the plurality of first conductors and the one or a plurality of second conductors are conducted. One or a plurality of solder paste bodies that are disposed at one or a plurality of planned intersections according to the combination to be planned and contain a low melting point metal, and are laminated in a region other than the solder paste bodies, and an adhesive layer and an insulating resin And a softening temperature of the insulating resin layer is higher than a softening temperature of the adhesive layer.

  The flat cable branching connection sheet has a solder paste body disposed at a planned intersection of the first conductor and the second conductor to be conducted, and a base material layer laminated in a region other than the solder paste body. For this reason, the flat cable branch connection sheet can be provided between the first conductor and the second conductor and thermocompression bonded to obtain a branch structure in which these conductors are easily connected. In addition, since the softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer, the flat cable branch connection sheet adjusts the thermocompression bonding temperature to ensure insulation and maintain the flat cable body and flat cable. The laminated portion with the branch body can be securely bonded, and has high adhesive strength and connection reliability. Furthermore, since the arrangement of the solder paste body of the flat cable branch 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. Correspondence is possible. Therefore, the flat cable branch connection sheet can easily and surely connect the first conductor of the flat cable body and the second conductor of the flat cable branch body to branch the flat cable.

  It is preferable that the solder paste body protrudes from one surface of the base material layer. By protruding the solder paste body from the one surface of the base material layer in this way, the adhesive is prevented from entering between the conductor and the solder paste body, and the first conductor and the second conductor are more reliably electrically connected. Can be connected to.

  The average protrusion height from one surface of the base layer of the solder paste body is preferably 10 μm or more and 100 μm or less, and the average print width of the solder paste body is preferably 0.2 mm or more and 0.8 mm or less. Thus, by making the average protrusion height and average print width from one surface of the base material layer of the solder paste body within the above range, the electrical strength between the conductors can be maintained while maintaining the adhesive strength between the pair of conductors. Connection can be made easier and more reliable.

  The base material layer has one or a plurality of through holes, and the solder paste body is preferably disposed in the through holes, and a difference obtained by subtracting the average diameter of the through holes from the average print width of the solder paste body. Is preferably 0.01 mm or more and 0.3 mm or less. Thus, by setting the difference between the average printing width of the solder paste body and the average diameter of the through-holes within the above range, it is possible to prevent the solder paste body from falling off, and the positional accuracy when the solder paste body is formed by printing. Can be increased.

  In the flat cable branch connection sheet, at least one surface may be flat. Thus, for example, by making the bottom surface of the solder paste body flush with the base material layer (flat) so that one surface is flat, the connection sheet for branching the flat cable to the first conductor or the second conductor. In addition to facilitating positioning when laminating, the one surface of the base material layer can be more securely bonded to the flat cable body or the flat cable branch, thus further improving the adhesive strength of the resulting flat cable branch structure. Can be increased.

  Further, the present invention crosses a flat cable 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. A method of manufacturing a flat cable branching connection sheet in which a plurality of first conductors and one or a plurality of second conductors are electrically connected in an arbitrary combination in an overlaid state, and an insulating resin layer on one surface of an adhesive layer And a step of forming a through hole in one or a plurality of planned intersections related to a combination of conducting a plurality of first conductors and one or a plurality of second conductors in the adhesive layer and the insulating resin layer, Printing a solder paste containing a low melting point metal in the through hole, and a method for producing a flat cable branching connection sheet in which the softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer Including.

  The manufacturing method of the flat cable branch connection sheet can easily and reliably manufacture the flat cable branch connection sheet.

  The “softening temperature” means a softening temperature measured according to JIS-K7196 (1991). The “average protrusion height from one surface of the base material layer of the solder paste body” means the average height of the solder paste body minus the average thickness of the base material layer. “The average print width of the solder paste body” means the average value of the diameters of the circles when the larger one of the areas on one side and the other side of the base layer of the solder paste body is converted into a perfect circle. means. The “average diameter of the through holes” means the average value of the diameters of the circles when the cross section of the through holes is converted into a perfect circle.

[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.

  A flat cable branch connection sheet 1 shown in FIG. 1 includes a flat cable body 2 having a plurality of first conductors 2a arranged in a stripe shape shown in FIG. 5, and a plurality of stripe cable arrangements shown in FIG. A plurality of first conductors 2a and a plurality of second conductors 3a are electrically connected in an arbitrary combination in a state where the flat cable branch bodies 3 having the second conductors 3a are overlapped so as to cross each other, and the flat cable shown in FIG. 2 is a connection sheet for obtaining a branch structure 10.

  The flat cable branch connection sheet 1 is disposed at each of a plurality of planned intersections related to the combination of conducting the plurality of first conductors 2a and the plurality of second conductors 3a, and contains solder having a low melting point. A paste body 1a and a base material layer 1b laminated in a region other than the solder paste body 1a are provided. The base material layer 1b includes an insulating resin layer 1c and a connection sheet adhesive layer 1d laminated on the surface of the insulating resin layer 1c. That is, the flat cable branch connection sheet 1 includes the base material layer 1b and a plurality of solder paste bodies 1a arranged in a scattered manner so as to penetrate the base material layer 1b. Specifically, the base material layer 1b has a plurality of through holes, and a plurality of solder paste bodies 1a are disposed in the through holes.

  The arrangement of the solder paste body 1a will be specifically described with reference to FIGS. 1, 5, and 7. FIG. 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 said flat cable branching connection sheet | seat 1 be crossing part Rnm. For example, the region where the conductor P1 and the conductor Q3 intersect is the intersection R13.

  In the flat cable branch structure 10 in which the flat cable body 2 and the flat cable branch 3 are connected, the conductor P1 and the conductor Q1, the conductor P2 and the conductor Q2, and 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 solder paste bodies 1a are respectively disposed at the planned intersections. Crossing portions R12, R13, R21, R23, R31, and R32 other than the first crossing portion are second crossing portions where conductors of a combination that is not conducted cross each other, and solder paste body 1a is disposed at these planned crossing portions. Not.

  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 intersecting portions R12, R23, R31 become the first intersecting portion, and the solder paste body 1a is disposed at these planned intersecting portions.

  As shown in FIG. 2, the solder paste body 1a protrudes from the surface of the connection sheet adhesive layer 1d. The bottom surface of the solder paste body 1a is flush with the back surface of the connection sheet adhesive layer 1d so that the back surface of the flat cable branch connection sheet 1 is flat. Furthermore, it is preferable that the surface side of the solder paste body 1a has a convex shape as shown in FIG. Thus, by making the solder paste body 1a into a convex shape, the contact pressure to the 2nd conductor 3a can be raised, and the 2nd conductor 3a and the solder paste body 1a can be more electrically connected.

  The planar shape of the solder paste body 1a is not particularly limited and may be any shape such as a circle or a rectangle, but isotropic considering the connectivity with the intersecting first conductor 2a and second conductor 3a. A shape such as a circular shape having properties is preferable.

  As a minimum of average printing width d1 of solder paste object 1a, 0.2 mm is preferred and 0.25 mm is more preferred. On the other hand, the upper limit of the average printing width d1 of the solder paste body 1a is preferably 0.8 mm, and more preferably 0.7 mm. When the average printing width d1 of the solder paste body 1a is less than the lower limit, there is a possibility that the electrical conductivity between the first conductor 2a and the second conductor 3a is insufficient. On the other hand, when the average printing width d1 of the solder paste body 1a exceeds the above upper limit, the solder flows out from the through hole of the base material layer 1b when the first conductor 2a and the second conductor 3a are connected, and other conductors that are not conductive. There is a risk that the adhesive strength of the flat cable branching structure 10 will be insufficient due to the risk of contact with the flat cable branching structure 10 due to a reduction in the planar area of the connection sheet adhesive layer 1d. In addition, when the second conductor 3a has a convex portion 3c described later, the printing width of the solder paste body 1a may be substantially the same as the width of the convex portion 3c and smaller than the width of the second conductor 3a. preferable. Specifically, the average print width of the solder paste body 1a is preferably 50% or more and 250% or less of the average width of the convex portions 3c of the second conductor 3a. In addition, the average width of the convex part 3c means the average width of the convex part 3c in the height of the opposing surface (except a convex part) of the 2nd conductor 3a with respect to the 1st conductor 2a.

  The lower limit of the average protrusion height from the surface of the connection sheet adhesive layer 1d of the solder paste body 1a is preferably 10 μm, and more preferably 30 μm. On the other hand, the upper limit of the average protrusion height from the surface of the connection sheet adhesive layer 1d of the solder paste body 1a is preferably 100 μm, and more preferably 80 μm. When the average protrusion height from the surface of the connection sheet adhesive layer 1d of the solder paste body 1a is less than the lower limit, the adhesive enters between the solder paste body 1a 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. Conversely, when the average protrusion height of the solder paste body 1a from the surface of the connection sheet adhesive layer 1d exceeds the above upper limit, the adhesive around the solder paste body 1a is not sufficiently filled, and the flat cable branching structure 10 Adhesive strength may be insufficient.

  The insulating resin layer 1c constituting the base material layer 1b is formed of an insulating resin disposed around the solder paste body 1a in plan view. Moreover, the softening temperature and glass transition temperature of the insulating resin layer 1c are higher than the connection sheet adhesive layer 1d described later. As an insulating resin which is a main component of the insulating resin layer 1c, an insulating resin having a high insulating property and a high softening temperature and glass transition temperature is preferable. Specific examples of the material of the insulating resin layer 1c include thermoplastic resins such as polyester, polyamide, acrylic resin, polyacetal, and phenoxy resin. A thermosetting adhesive such as epoxy can also be used. In addition, a glass transition temperature means the midpoint glass transition temperature measured based on JIS-K7121 (1987).

  As a minimum of the softening temperature of insulating resin layer 1c, 80 ° C is preferred, 110 ° C is more preferred, and 120 ° C is still more preferred. When the softening temperature of the insulating resin layer 1c is less than the lower limit, the insulating resin layer 1c may be softened and deformed when the flat cable branch structure 10 is thermocompression bonded. On the other hand, the upper limit of the softening temperature of the insulating resin layer 1c is not particularly limited, but may be, for example, 200 ° C.

  As a minimum of glass transition temperature of insulating resin layer 1c, 70 ° C is preferred, 75 ° C is more preferred, and 80 ° C is still more preferred. When the glass transition temperature of the insulating resin layer 1c is less than the above lower limit, the strength of the insulating resin layer 1c after the thermocompression bonding of the flat cable branch structure 10 may be insufficient. On the other hand, the upper limit of the glass transition temperature of the insulating resin layer 1c is not particularly limited, but may be, for example, 200 ° C.

  It is preferable to add a curing agent to the resin constituting the insulating resin layer 1c 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 insulating resin layer 1c is not specifically limited, For example, the method of printing by dissolving 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 thickness of the insulating resin layer 1c is preferably 1 μm and more preferably 5 μm. On the other hand, the upper limit of the average thickness of the insulating resin layer 1c is preferably 30 μm and more preferably 20 mm. When the average thickness of the insulating resin layer 1c is less than the above 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. Conversely, when the average thickness of the insulating resin layer 1c exceeds the above upper limit, the flat cable branch structure 10 may be unnecessarily thick.

  The connection sheet adhesive layer 1d constituting the base material layer 1b is laminated on the surface (surface on the second conductor 3a side) of the insulating resin layer 1c, and fills the periphery of the solder paste body 1a in plan view. It is formed with. Further, the connection sheet adhesive layer 1d has a softening temperature and a glass transition temperature lower than those of the insulating resin layer 1c. The adhesive forming the connection sheet adhesive layer 1d is preferably a thermoplastic resin, and examples thereof include polyamide, polyester, acrylic resin, melamine resin, polyamideimide, polyacetal, and phenoxy resin.

  Note that a colorant such as a pigment may be added to the connection sheet adhesive layer 1d 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 1d is preferably 150 ° C, more preferably 140 ° C, and further preferably 130 ° C. On the other hand, the lower limit of the softening temperature of the connection sheet adhesive layer 1d is preferably 50 ° C, and more preferably 60 ° C. When the softening temperature of the connection sheet adhesive layer 1d exceeds the above upper limit, the temperature at the time of thermocompression bonding of the flat cable branch structure 10 needs to be increased, so that productivity may be lowered. Conversely, when the softening temperature of the connection sheet adhesive layer 1d is less than the above lower limit, the heat resistance (strength maintenance at high temperature) of the flat cable branch structure 10 may be insufficient.

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

  The upper limit of the average thickness of the connection sheet adhesive layer 1d is preferably 50 μm, and more preferably 35 μm. On the other hand, the lower limit of the average thickness of the connection sheet adhesive layer 1d is preferably 1 μm and more preferably 5 μm. When the average thickness of the connection sheet adhesive layer 1d exceeds the above upper limit, the electrical connectivity between the conductors by the solder paste body 1a may be reduced, and the flat cable branch structure 10 may be unnecessarily thick. Conversely, when the average thickness of the connection sheet adhesive layer 1d is less than the lower limit, the adhesive strength of the flat cable branch structure 10 may be insufficient.

[Manufacturing method of flat cable branch connection sheet]
The flat cable branch connection sheet 1 can be manufactured, for example, by the following method.

  First, as shown in FIG. 3A, an adhesive is printed or coated on the surface of the release film X, and the locations where the plurality of solder paste bodies 1a are disposed (conduction between the plurality of first conductors 2a and the plurality of second conductors 3a). 1 d of connection sheet adhesive layers which have a through-hole are formed in the some crossing part which concerns on the combination which aims at. The method for printing the adhesive is not particularly limited, and for example, screen printing, gravure printing, offset printing, flexographic printing, inkjet printing, dispenser printing, and the like can be used. As the solvent used for the adhesive, a solvent having a high boiling point is preferable so as not to cause clogging during printing, and for example, isophorone, benzyl alcohol, butyl carbitol acetate, cyclohexane and the like can be used. Moreover, after printing the adhesive, it is preferably dried at a temperature of 70 ° C. or more and 90 ° C. or less, for example, for 10 minutes or more and 60 minutes or less.

  The lower limit of the difference obtained by subtracting the average diameter of the through holes of the base material layer 1b from the average printing width d1 of the solder paste body 1a is preferably 0.01 mm, and more preferably 0.05 mm. On the other hand, the upper limit of the difference is preferably 0.3 mm, and more preferably 0.2 mm. When the difference is less than the lower limit, the solder paste body 1a may drop off from the through hole, or high printing accuracy may be required. Conversely, when the difference exceeds the upper limit, the solder may flow out of the through hole of the base material layer 1b when connecting the first conductor 2a and the second conductor 3a, and may contact other conductors that are not conductive.

  Next, as shown in FIG. 3B, an insulating resin layer 1c having a through hole at the location where the solder paste body 1a is disposed is laminated on the surface of the connection sheet adhesive layer 1d to form a base material layer 1b. As a method of laminating the insulating resin layer 1c, a method of sticking an insulating film in which a through hole is formed, a method of printing or coating a resin composition, or the like can be used. Moreover, when forming the insulating resin layer 1c by printing, it is preferable to dry it for 10 minutes or more and 60 minutes or less after printing, for example at the temperature of 70 degreeC or more and 90 degrees C or less.

  In addition, after forming a connection sheet adhesive layer having no through-hole, laminating an insulating resin layer having no through-hole on this connection sheet adhesive layer, a through-hole filled with solder paste is processed and formed. Also good.

  After forming the base material layer 1b, as shown in FIG. 3C, the solder paste is printed in the through holes to form the solder paste body 1a. The solder paste printing method may be the same as the adhesive printing method. At this time, it is preferable to form the solder paste body 1a so as to protrude from the surface of the base material layer 1b. In addition, it is preferable to make the diameter of a through-hole smaller than the printing width of the solder paste body 1a mentioned later. Thereby, the solder paste body 1a can be easily protruded from the surface of the base material layer 1b.

  As said solder paste, what knead | mixed the low melting metal powder (it is not limited to a lead-tin alloy) with the flux can be used. Examples of the metal powder (solder) include a tin-bismuth alloy having a melting point of 139 ° C. The particle diameter of the metal powder is preferably 5 μm or more and 40 μm or less. When the solder is melted, it spreads over the entire area between the opposing surfaces of the first conductor 2a and the second conductor 3a due to wettability, so that the electrical connection reliability of the first conductor 2a and the second conductor 3a is improved. The solder paste flux is preferably one that can contribute to the wettability of the solder, and a resin-based, organic acid-based or inorganic acid-based one can be used. Moreover, as content of the metal powder of solder paste, it can be set as 80 to 95 mass%, for example.

  After forming the solder paste body 1a, the release film X is peeled off to obtain the flat cable branch connection sheet 1. 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.

[How to use the flat cable branch connection sheet]
By using the flat cable branch connection sheet, the flat cable branch structure 10 shown in FIG. 4 can be obtained easily and reliably. The flat cable branching structure 10 is arranged in the stripe shape shown in FIGS. 7 and 8 and the flat cable body 2 having a plurality of first conductors 2a arranged in the stripe shape shown in FIGS. The flat cable branch body 3 having a plurality of second conductors 3a is directly superimposed 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 10 includes the flat cable branching connection sheet 1 laminated between the first conductor 2a and the second conductor 3a disposed to face each other, and a protective film adhesive layer on the outer surface side of the second conductor 3a. The protective film 5 is covered via 5a, and the reinforcing film 6 is covered on the outer surface side of the first conductor 2a via the reinforcing film adhesive layer 6a.

  In the flat cable branch structure 10, the solder paste body 1 a of the flat cable branch connection sheet 1 is filled as a solder 1 e between a convex portion 3 c, which will be described later, of the second conductor 3 a and the first conductor 2 a, and the base layer 1b is laminated | stacked on the area | region surrounding the filling area | region of the solder | pewter 1e. In the flat cable branch structure 10, the solder 1e is disposed in a through hole formed in the base material layer 1b, and a space is formed between the solder 1e and the insulating resin layer 1c. This space is formed by the flow of the solder paste body 1a during heating.

<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.

  As a minimum of average thickness (a plating layer is included) of the 1st conductor 2a, 10 micrometers is preferred and 25 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the first conductor 2a is preferably 100 μm, and more preferably 80 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. Conversely, when the average thickness of the first conductor 2a exceeds the above upper limit, the flat cable branch structure 10 may become 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. 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 first conductor 2a is less than the above lower limit, the conductivity may be insufficient. Conversely, when the average width of the first conductor 2a exceeds the above upper limit, the width of the flat cable branch structure 10 may become unnecessarily large.

  As a minimum of the average pitch of the 1st conductor 2a, 0.2 mm is preferred and 0.3 mm is more preferred. On the other hand, the upper limit of the average pitch of the first conductors 2a is preferably 1.5 mm, and more preferably 1.2 mm. When the average pitch of the first conductors 2a is less than the lower limit, adjacent first conductors 2a may come into contact with each other. Conversely, when the average pitch of the first conductors 2a exceeds the above upper limit, the width of the flat cable branch structure 10 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 for this resin film, for example, polyimide, polyethylene terephthalate 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 10 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.

  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 10 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.

  As a minimum of average thickness of insulating film 2b, 5 micrometers is preferred and 10 micrometers is more preferred. 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 is less than the above lower limit, the strength of the insulating film 2b may be insufficient. Conversely, when the average thickness of the insulating film 2b exceeds the above upper limit, the flat cable branch structure 10 may become unnecessarily thick.

  The adhesive constituting the flat cable adhesive layer 2c is not particularly limited, but preferably has excellent flexibility and heat resistance. Examples of such adhesives include epoxy resins, polyimides, polyesters, Various resin-based adhesives such as phenol resin, polyurethane, acrylic resin, melamine resin, polyamideimide and the like can be mentioned. Among these, those which are thermoplastic and have a softening temperature and a glass transition temperature lower than the insulating resin layer 1c of the flat cable branch connection sheet 1 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 branching structure 10 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 10 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. 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 is less than the above lower limit, the adhesive strength between the insulating film 2b and the first conductor 2a may be insufficient. Conversely, when the average thickness of the flat cable adhesive layer 2c exceeds the above upper limit, the flat cable branch structure 10 may become unnecessarily thick.

  The flat cable body 2 does not have the insulating film 2b and the adhesive in the region where the flat cable main body 2 intersects and overlaps the flat cable branch body 3 (hereinafter may be referred to as the overlapping region). The side facing the two conductors 3a (front side) and the outer side (back side) are exposed. The flat cable branch connection sheet 1 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. In addition, a reinforcing film 6 described later is laminated on the back surface of the overlapping region where the first conductor 2a is exposed.

<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 flat cable branch connection sheet 1 laminated on the surface of the overlapping region. Specifically, the plurality of second conductors 3a are laminated so as to intersect the plurality of first conductors 2a substantially at right angles via the flat cable branch connection sheet 1, respectively.

  The plurality of second conductors 3a each have a convex portion 3c that protrudes in a direction opposite to the first conductor 2a at a first intersecting portion related to the combination with the first conductor 2a.

  The convex portion 3c is formed in a spherical shape by a stamping molding method for a plate-like conductor. Specifically, as shown in FIGS. 9A, 9B, and 9C, a heat tool Y having a cushion Y1 on the lower surface and a mold Z having a convex portion on the surface are used. The convex portion 3c can be formed by pressing the second conductor 3a.

  As a minimum of average projection height of the above-mentioned convex part 3c, 0.06 mm is preferred and 0.1 mm is more preferred. On the other hand, as an upper limit of the average protrusion height of the convex part 3c, 0.2 mm is preferable and 0.15 mm is more preferable. When the average protrusion height of the convex portion 3c is less than the lower limit, the space in which the solder stays between the second conductor 3a and the first conductor 2a becomes small, which may reduce the connection reliability. On the contrary, when the average protrusion height of the convex part 3c exceeds the said upper limit, the distance of the 1st conductor 2a and the 2nd conductor 3a becomes large, and there exists a possibility that the adhesive strength of the flat cable branch structure 10 may fall.

  As a minimum of average curvature radius R of the above-mentioned convex part 3c, 0.1 mm is preferred and 0.15 mm is more preferred. On the other hand, as an upper limit of the average curvature radius R of the convex part 3c, 0.3 mm is preferable and 0.25 mm is more preferable. When the average radius of curvature R of the convex portion 3c is less than the lower limit, the connection area between the second conductor 3a and the first conductor 2a becomes small, which may reduce the connection reliability. Conversely, when the average radius of curvature R of the convex portion 3c exceeds the above upper limit, the space in which the solder stays between the second conductor 3a and the first conductor 2a becomes small, and the connection reliability may be reduced. .

<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. In addition, it is preferable that the protective film adhesive layer 5a has a softening temperature and a glass transition temperature lower than the insulating resin layer 1c of the flat cable branch connection sheet 1.

  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. 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 exceeds the above upper limit, the temperature at the time of thermocompression bonding of the flat cable branch structure 10 needs to be increased, so that productivity may be lowered. Conversely, 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 10 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. 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 exceeds the above upper limit, the adhesive strength of the flat cable branch structure 10 may be insufficient. Conversely, 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 10 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. 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 1st conductor 2a to the back surface of the protective film 5 exceeds the said upper limit, there exists a possibility that the flat cable branch structure 10 may become thick unnecessarily. On the contrary, 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 amount of the adhesive is reduced, and the adhesive strength of the flat cable branch structure 10 may be insufficient. is there.

<Reinforcing film>
The reinforcing film 6 is an insulating film laminated on the back side of the first conductor 2a via the reinforcing film adhesive layer 6a.

  As the material of the reinforcing film 6, the same material as the insulating film 2b of the flat cable body 2 can be used.

  As a minimum of average thickness of reinforcing film 6, 100 micrometers is preferred and 200 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the reinforcing film 6 is preferably 400 μm, and more preferably 300 μm. When the average thickness of the reinforcing film 6 is less than the above lower limit, it is difficult to temporarily fix the flat cable body 2 or the like before the flat cable branching structure 10 is crimped, and the reinforcing effect of the flat cable branching structure 10 is sufficiently obtained. There is a risk of not being able to. Conversely, when the average thickness of the reinforcing film 6 exceeds the above upper limit, the flat cable branch structure 10 may become unnecessarily thick.

  The length of the reinforcing film 6 in the longitudinal direction of the conductor and the length in the lateral direction of the conductor are larger than the length of the overlapping region in the longitudinal direction of the conductor and the length in the lateral direction of the conductor, respectively. As a result, the flat cable branch connection sheet 1, the flat cable main body 2 and the flat cable branch body 3 are fixed to the surface of the reinforcing film 6 (the surface of the reinforcing film adhesive layer 6a), and these are positioned before thermocompression bonding. Can be easily and reliably performed.

  The lower limit of the conductor longitudinal direction length d2 of the laminated region of the reinforcing film 6 and the insulating film of the flat cable body 2 or the flat cable branch body 3 is preferably 1 mm, and more preferably 1.5 mm. On the other hand, the upper limit of the conductor longitudinal direction length d2 of the laminated region of the reinforcing film 6 and the insulating film of the flat cable main body 2 or the flat cable branch body 3 is preferably 4 mm, and more preferably 3 mm. If the length d2 of the conductor in the laminated region in the longitudinal direction is less than the lower limit, it may be difficult to temporarily fix the flat cable body 2 or the flat cable branch body 3 before the flat cable branch structure 10 is crimped. There is a possibility that the reinforcing effect of 10 cannot be obtained sufficiently. On the contrary, when the conductor longitudinal direction length d2 of the said lamination | stacking area | region exceeds the said upper limit, there exists a possibility that the thick part (reinforcement part) of the flat cable branch structure 10 may increase more than necessary.

  The material and average thickness of the reinforcing film adhesive layer 6 a can be the same as those of the flat cable adhesive layer 2 c of the flat cable body 2.

<Manufacturing method of flat cable branching structure>
The flat cable branching structure 10 can be easily and reliably manufactured by, for example, a manufacturing method including the following steps.
(1) Step of exposing both sides of overlapping region of first conductor 2a of flat cable body 2 (2) Step of exposing both sides of end portion of second conductor 3a of flat cable branch body 3 (3) Second (4) The step of laminating the flat cable body 2 on the surface of the reinforcing film 6 (5) The first conductor 2a and the first step Step of superimposing the flat cable branch connection sheet 1 between the two conductors 3a (6) Step of laminating the protective film 5 on the opposite side of the second conductor 3a (7) First conductor 2a, second conductor 3a The process of thermocompression bonding the flat cable branch connecting sheet 1, the protective film 5 and the reinforcing film 6

<(1) First conductor exposure step>
In the first conductor exposing step, the insulating film 2b on both sides is peeled and the adhesive is removed in a region (superimposed region) that intersects and overlaps the flat cable branch 3 of the flat cable body 2. Thereby, both surfaces of the first conductor 2a are 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) Convex part formation process>
In the convex portion forming step, the convex portions 3c are respectively formed at the positions corresponding to the exposed first intersecting portions of the plurality of second conductors 3a by the stamping molding method shown in FIGS.

<(4) Flat cable body lamination process>
In the flat cable main body laminating step, as shown in FIG. 10A, the flat cable main body 2 is laminated so that the overlapping portion of the flat cable main body 2 comes to the center in the longitudinal central portion of the surface of the reinforcing film 6 (surface of the reinforcing film adhesive layer 6a). Temporarily fix.

<(5) Superposition process>
In the superimposing step, the flat cable branch connection sheet 1 having the solder paste body 1a is laminated on the surface of the first conductor 2a as shown in FIG. 10B, and the flat cable branch body 3 is further formed on the surface as shown in FIG. 10C. The second conductor 3a is laminated, and the flat cable branch connection sheet 1 is overlapped between these conductors. At this time, it adjusts so that the convex part 3c and the solder paste body 1a may be located in each 1st cross | intersection part where the 1st conductor 2a and the 2nd conductor 3a cross | intersect.

<(6) Protective film lamination process>
In the protective film laminating step, as shown in FIG. 10D, the protective film 5 in which the protective film adhesive layer 5a is 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. 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 exceeds the above upper limit, the adhesive may enter between the first conductor 2a and the solder paste body 1a, and the connectivity may be reduced. There is a possibility that the branch structure portion of the cable branch structure 10 becomes unnecessarily thick. On the contrary, 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, that is, it adheres around the solder paste body 1a by indentation at the time of thermocompression bonding There is a possibility that the adhesive strength of the branch structure portion of the flat cable branching structure 10 becomes insufficient because the agent is not filled.

<(7) Thermocompression bonding process>
In the thermocompression bonding step, the laminated body of the first conductor 2a, the second conductor 3a, the flat cable branch connection sheet 1, the protective film 5, and the reinforcing film 6 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 less than the melting point of the solder paste body 1a and not more than the softening temperature of the insulating resin layer 1c, the insulating film of the flat cable body 2 and the flat cable branch body 3, and the protective film 5, and The connecting sheet adhesive layer 1d of the connecting sheet 1 for flat cable branching, the flat cable adhesive layer 2c of the flat cable body 2, and the glass transition temperature of the protective film adhesive layer 5a are preferably higher than the glass transition temperature, the insulating resin layer 1c, The insulating film of the flat cable main body 2 and the flat cable branch 3 and the glass transition temperature of the protective film 5 or lower, the connection sheet adhesive layer 1d of the flat cable branch connection sheet 1, and the flat cable adhesive of the flat cable main body 2 Layer 2c and protective film adhesive layer 5a It is more preferably not less than temperature. By setting the heating temperature in this way, the solder paste can be flowed and solidified while the adhesive is softened and the members can be securely bonded while suppressing deformation of the insulating films.

  The specific heating temperature in the thermocompression bonding step can be set to 50 ° C. or more and 200 ° C. or less, for example. Moreover, as a pressurization load in a thermocompression bonding process, it can be set as 0.5 MPa or more and 5 MPa or less, for example, As a pressurization time, it can be set as 1 second or more and 30 seconds or less, for example.

  In this thermocompression bonding step, the solder paste body 1a filled in the through hole of the base material layer 1b of the flat cable branch connection sheet 1 flows, and between the insulating resin layer 1c of the base material layer 1b and the solder 1e. A space as shown in FIG. 4 is formed.

  In the flat cable branching structure 10, the protective film 5 is formed at the end of the branching structure, and the protective film 5 does not face the insulating film of the flat cable main body 2 or the flat cable branching body 3 (the insulating film is laminated only on one side). Area) is easily bent by 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.

[advantage]
The flat cable branching connection sheet 1 includes a solder paste body 1a disposed at a planned intersection of the first conductor and the second conductor to be conducted, and a base material layer 1b laminated in a region other than the solder paste body 1a. And have. Therefore, the flat cable branch connection sheet 1 can be provided between the first conductor and the second conductor and thermocompression bonded to obtain a branch structure in which these conductors are easily connected. In addition, the flat cable branch connection sheet 1 is flat while maintaining insulation by adjusting the thermocompression bonding temperature because the softening temperature of the insulating resin layer 1c is higher than the softening temperature of the connection sheet adhesive layer 1d. The laminated portion of the cable body and the flat cable branch can be securely bonded, and has high adhesive strength and connection reliability. Furthermore, since the arrangement of the solder paste body 1a of the flat cable branch connection sheet 1 can be changed as appropriate, the number of first conductors and second conductors, the combination of conductors to be conducted, the crossing angle, etc. may change. It can be easily handled. Therefore, the flat cable branch connection sheet 1 can easily and reliably connect the first conductor of the flat cable main body and the second conductor of the flat cable branch body to branch the flat cable.

  Moreover, since the said solder paste body 1a protrudes from the connection sheet adhesive bond layer 1d surface, the said 1st conductor and the 2nd conductor can be electrically connected more reliably in the said connection sheet 1 for flat cable branching. . Furthermore, since the back surface of the flat cable branch connection sheet 1 is flat, that is, the bottom surface of the solder paste body 1a is flush with the back surface of the connection sheet adhesive layer 1d, the flat cable branch connection sheet 1 is used as the first conductor. In addition to facilitating positioning at the time of lamination, it is possible to more reliably bond the back surface of the connection sheet adhesive layer 1d to the flat cable body, thereby further increasing the adhesive strength.

  The flat cable branch connection sheet 1 can be easily handled by appropriately changing the position of the solder paste body 1a even if the number of the first conductors and the second conductors and the combination of conductors to be changed are changed. can do.

[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 usage example of the flat cable branch connection sheet in the embodiment, the protruding side of the solder paste body of the flat cable branch connection sheet comes into contact with the second conductor, and the flat surface is laminated on the first conductor. However, the flat cable branch connection sheet may be disposed so that the side on which the solder paste body protrudes contacts the first conductor. However, in order to stably arrange the flat cable branch connection sheet and to ensure filling between the conductors of the solder, the flat cable branch connection sheet is arranged so that the flat surface is laminated on the first conductor. It is preferable to arrange.

  Furthermore, the solder paste body does not necessarily have to 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. In addition, the flat cable branch connection sheet may have an adhesive layer on both sides of the insulating resin layer.

  Further, in the usage example of the flat cable branch connection sheet in the above embodiment, the flat cable body and the flat cable branch body are overlapped so as to intersect at a substantially right angle, but the flat cable body and the flat cable branch body are It is also possible to intersect at other angles. Also in this case, the flat cable branch connection sheet can be obtained by disposing a solder paste body at the planned intersection of the first conductor and the second conductor formed by the intersection of the flat cable body and the flat cable branch. A flat cable branch structure 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.

  Moreover, in the said embodiment, although the 2nd conductor of the flat cable branch body had the convex part, you may use the 2nd conductor which does not have such a convex part. Moreover, you may form a convex part in the opposing part with the 2nd conductor of the 1st conductor of a flat cable main body.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[No. 1-7]
A flat cable branch connection sheet for creating a flat cable branch structure shown in FIG. 4 in which a flat cable branch body having three second conductors is intersected at right angles to a flat cable body having three first conductors. No. 1 to No. Created up to 7. The average print widths of the solder paste bodies of these flat cable branch connection sheets are the values shown in Table 1, and the average diameters of the through holes for filling the solder paste bodies of the flat cable branch connection sheets are those of the solder paste bodies. It was formed 0.1 mm smaller than the printing width. Moreover, the printing height of the solder paste body was about 100 μm, the average thickness of the insulating resin layer was 12 μm, and the average thickness of the connection sheet adhesive layer was 30 μm. The average thickness of the first conductor and the second conductor was 0.05 mm, the width was 0.7 mm, and the pitch was 1 mm. The second conductor was formed with a convex portion having an average radius of curvature of 0.15 mm and an average protrusion height of 0.15 mm at the intersection with the first conductor.

  No. above. The flat cable branch structure was created using the connection sheet for flat cable branches of 1-7, and the following tests were done about this flat cable branch structure. The results are shown in Table 1, respectively.

[Insulation test]
A direct current of 500 V was passed through each conductor of the flat cable branch structure for 30 seconds, and the resistance value between the first conductor and the second conductor was measured. A measured resistance value of 100 MΩ or more was evaluated as A, and a resistance value of less than 100 MΩ was evaluated as B.

[Torsion test]
After pressing the back surface of the flat cable branch structure around the circumference of a cylinder having a radius (R) of 15 mm or 5 mm, the surface of the flat cable branch structure is pressed so as to be similarly wound around the same cylinder. After performing this 15 times on the back and front surfaces, the resistance value between the first conductor and the second conductor was measured, and the increase from the resistance value before the test was measured. A resistance increase value of 10 mΩ or less was evaluated as A, and a resistance value exceeding 10 mΩ was evaluated as B.

  As can be seen from Table 1 above, flat cable branching is excellent in insulation and connection reliability (twist resistance) by setting the printed width of the solder paste body of the flat cable branching connection sheet to 0.5 mm to 0.7 mm. It can be seen that the structure is obtained.

  The flat cable branch connection sheet of the present invention is excellent in adhesive strength and electrical connection reliability, and can easily and reliably connect intersecting flat cable conductors.

DESCRIPTION OF SYMBOLS 1 Connection sheet 1a for flat cable branch Solder paste body 1b Base material layer 1c Insulating resin layer 1d Connection sheet adhesive layer 1e Solder 2 Flat cable body 2a First conductor 2b Insulating film 2c Flat cable adhesive layer 3 Flat cable branch body 3a Second conductor 3b Insulating film 3c Convex part 5 Protective film 5a Protective film adhesive layer 6 Reinforcing film 6a Reinforcing film adhesive layer 10 Flat cable branching structure X Release film Y Heat tool Y1 Cushion Z Mold

Claims (6)

A plurality of flat cable bodies having a plurality of first conductors arranged in stripes and a flat cable branching body having one or more second conductors arranged in stripes are overlapped so as to cross each other. A flat cable branching connection sheet for conducting the first conductor and one or a plurality of second conductors in any combination,
One or a plurality of solder paste bodies that are arranged for each of one or a plurality of crossing-scheduled portions related to a combination of conducting a plurality of first conductors and one or a plurality of second conductors, and contain a low melting point metal;
It is laminated in a region other than the solder paste body, and includes a base material layer including an adhesive layer and an insulating resin layer,
A flat cable branching connection sheet in which the softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer.   The flat cable branch connection sheet according to claim 1, wherein the solder paste body protrudes from one surface of the base material layer.   3. The flat cable according to claim 2, wherein an average protrusion height from one surface of the base material layer of the solder paste body is 10 μm to 100 μm, and an average printing width of the solder paste body is 0.2 mm to 0.8 mm. Branch connection sheet.   The base material layer has one or a plurality of through holes, and the solder paste body is disposed in the through holes. The difference obtained by subtracting the average diameter of the through holes from the average print width of the solder paste body is 0. The connecting sheet for flat cable branching according to claim 1, wherein the connecting sheet is from 01 mm to 0.3 mm.   The flat cable branch connection sheet according to any one of claims 1 to 4, wherein at least one surface is flat. A plurality of flat cable bodies having a plurality of first conductors arranged in stripes and a flat cable branching body having one or more second conductors arranged in stripes are overlapped so as to cross each other. A flat cable branching connection sheet for conducting a first conductor and one or a plurality of second conductors in any combination,
Laminating an insulating resin layer on one side of the adhesive layer;
A step of forming a through hole in one or a plurality of crossing-scheduled portions according to a combination of conducting a plurality of first conductors and one or a plurality of second conductors in the adhesive layer and the insulating resin layer;
A step of printing a solder paste containing a low melting point metal in the through hole,
A method for producing a connecting sheet for flat cable branching, wherein the softening temperature of the insulating resin layer is higher than the softening temperature of the adhesive layer.

Images