JP2004079482A - Flexible flat cable and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive flat cable, and its construction method, which can be manufactured under a high productivity. <P>SOLUTION: With the flexible flat cable provided with a plurality of flat conductors 12<SB>1</SB>, 12<SB>2</SB>and an insulating material 14 coating in bulk the plurality of the flat conductors 12<SB>1</SB>, 12<SB>2</SB>, the plurality of the conductors 12<SB>1</SB>, 12<SB>2</SB>are ones made by rolling conductors having a circular cross section shape, and the insulating material 14 is either transparent or translucent. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a flexible flat cable and a method for constructing the same.
[0002]
[Prior art]
A flexible flat cable (hereinafter, referred to as FFC) is a wiring member in which a conductor having a flat cross-sectional shape is covered with an insulating material. This FFC is more flexible and can be bent than a round electric wire composed of a conductor having a circular cross section and an insulating material covering the conductor, and can be formed by covering a plurality of conductors separated from each other collectively. It is easy to core. Further, since the FFC is thin, the space occupied by the electric wire itself can be minimized by using the FFC. For this reason, the FFC has been receiving attention as a wiring material used in automobiles and devices which have been increasingly multi-core due to complicated control.
[0003]
As a method of manufacturing such an FFC, a laminating method and an extrusion coating method are representative. According to the former laminating method, a flat conductor is sandwiched from above and below by a film-like insulating material having a width wider than that of the conductor and having an adhesive layer on its surface, and passes between heated rolls. Is done. As a result, the adhesive layers of the upper and lower insulating materials adhere or adhere to the conductor, and the conductor is covered with the insulating material. As the insulating material, a material obtained by applying or co-extruding an adhesive on the surface of an extremely thin film made of polyethylene terephthalate or the like is usually used.
[0004]
The latter extrusion coating method is disclosed in, for example, International Publication WO098 / 549057. According to this international publication, polyamide, polyolefin, and polyamide-based polymer alloy are mentioned as coating materials.
As described above, if the conductor included in the FFC is flat, that is, flat, and has the same cross-sectional area, the conductor of the FFC has a larger surface area and higher heat dissipation than the conductor of the round electric wire. In the case of a flat conductor, the smaller the thickness is, the larger the surface area becomes, and the heat dissipation becomes higher. As described above, since the flat conductor has a high heat radiation property, a rise in temperature during energization is suppressed, so that the FFC can be constituted by a conductor having a smaller cross-sectional area than a conductor having a round cross section. Therefore, according to the FFC, the amount of the conductive material used can be reduced, and the weight of the wiring member in the device can be reduced.
[0005]
The following two typical methods are used to manufacture this flat conductor. One of them is a slit method, in which a copper plate or copper foil made by rolling or electrolytic processing is slit. Another method is a rolling method, in which a conductor having a round cross-sectional shape is formed by being rolled and crushed.
As a method of connecting the above-mentioned FFC to a connection terminal of an electric circuit or the like, a method of stripping an insulating material to expose a conductor, and then welding or brazing the exposed portion of the conductor to a terminal of a mating material, or a method disclosed in As disclosed in JP-A-11-144780, there is known a method of piercing a piercing-type connection terminal from above an insulating material toward a conductor.
[0006]
However, the work of stripping the insulating material is troublesome when the insulating material and the conductor are in close contact with each other, and may also damage the conductor. It is preferable to use
Here, in general, the coating material has sufficient weather resistance in order to prevent the coating material from deteriorating, causing cracks and the like, and preventing corrosion of the internal conductor. Specifically, an opaque material containing a pigment or the like is used as a covering material of the electric wire.
[0007]
[Problems to be solved by the invention]
By the way, the above-mentioned laminating method has a problem that the production speed of the FFC is very slow, about 1 to 10 m per minute, and the productivity is low. This is because in the lamination method, heat is transferred from the heating roll to the adhesive layer of the insulating material through a film with low thermal conductivity, and a sufficient amount of heat required for adhesion or welding is applied to the adhesive layer. It takes time to give.
[0008]
In addition, the flat conductor manufactured by the slit method has a problem that it has a very high dimensional accuracy in width but is expensive.
On the other hand, a flat conductor manufactured by the rolling method can expect a significant cost reduction as compared with a flat conductor manufactured by the slit method. However, in general, flat conductors crushed by rolls meander greatly on both sides along the longitudinal direction, and when two or more FFCs are arranged in parallel, it is difficult to maintain the pitch between conductors with high precision. There is a problem.
[0009]
Regarding this problem, in the case of the laminating method, when the conductor is sandwiched between the films, the conductor is positioned with respect to the film while correcting the meandering of the flat conductor, whereby the pitch accuracy between the conductors can be improved. This means that the laminating method has a low production speed and makes it easy to correct the meandering of the conductor, while the conductor is fixed by the insulating material immediately after passing through the heat roll, so the restoring force returns to the meandering state before the correction. This is because, even when the conductor is present in the conductor, the adhesive force of the insulating material exceeds the restoring force. However, the problem that the production speed of the lamination method is low still remains.
[0010]
On the other hand, the extrusion coating method is a manufacturing method similar to the case of the conventional wire coating extrusion, and the manufacturing speed reaches several tens to several hundreds of meters per minute. Can be provided. However, when the extrusion coating method is used, immediately after the conductor and the insulating material are extruded from the extrusion head, the insulating material is in a molten or soft state. There is a problem that this cannot be effectively suppressed.
[0011]
When piercing the piercing-type connection terminal into the FFC having a low conductor-to-conductor pitch accuracy, it is necessary to reliably detect the position of the conductor in the insulating material in advance. However, extrusion coating materials used for electric wires are generally opaque, and when such an extrusion coating material is applied to an insulation material of an FFC, there is a problem that it is not easy to detect a conductor position in the insulation material. .
[0012]
An object of the present invention is to solve the above-mentioned problems and to provide an inexpensive flat cable that can be manufactured with high productivity.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a flexible board comprising: a plurality of flat conductors which are spaced apart from each other in a width direction and arranged in parallel; and an insulating material which collectively covers the plurality of flat conductors. In the flat cable, each of the plurality of flat conductors is a flat conductor obtained by rolling a conductor having a circular cross-sectional shape, and the flexible flat cable is characterized in that the insulating material is transparent or translucent. Provided (Claim 1).
[0014]
Further, in the present invention, the position of the flat conductor in the flat cable is confirmed by irradiating light from one side of the flat cable of claim 1 and receiving transmitted light on the other side. And piercing the piercing-type terminal.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a flexible flat cable (hereinafter, referred to as FFC and denoted by reference numeral 10) according to an embodiment of the present invention. The FFC 10 is used, for example, as a wiring member that connects between connection terminals of two printed circuit boards installed in an automobile.
[0016]
FFC10 has copper two conductors ₁₂ 1, 12 _2. Each conductor 12 ₁ , 12 ₂ has a thickness of 0.3 mm, a width of 2.5 mm, and a length of 500 mm.
Each of the conductors 12 ₁ and 12 ₂ is a flat conductor (hereinafter referred to as a rolled flat mold) formed by rolling a wire having a circular cross-sectional shape with a diameter of 1 mm using a roll. Conductor). Therefore, in each of the conductors 12 ₁ and 12 ₂ , both sides along the longitudinal direction meander as compared with the conductor manufactured by slit processing.
[0017]
In each conductor 12 _1, 12 _2, aspect ratio obtained by dividing the width thickness is preferably 2 or more. This is because the heat dissipation of the conductor can be increased.
The thickness of each of the conductors 12 ₁ and 12 ₂ is preferably 0.3 mm or less. This is because when the thickness of the conductor is 0.3 mm or less, the FFC containing the same has good bending workability.
[0018]
The conductors 12 ₁ and 12 ₂ are covered with the insulating material 14 except for their end faces. Specifically, the conductors 12 ₁ and 12 ₂ are covered with the insulating material 14 in a state where they are arranged in parallel at an interval of about 4 mm in their width direction.
The outer shape of the insulating material 14 is substantially rectangular and has a width of 8.5 mm, a thickness of 0.5 mm, and a length of 500 mm. The insulating material 14 is transparent or translucent, has good insulating properties, and consists of a material applicable for extrusion coating. As such a material, a known material can be used, except that the transmittance is adjusted by appropriately adjusting the addition amount of the pigment, and for example, a resin containing polyvinyl chloride, polyamide, or polyolefin as a main component. Compositions. As a suitable material for the insulating material 14, a polyester resin composition having better heat resistance than these known materials and described in the specification attached to the application of Japanese Patent Application No. 2001-166413 is exemplified.
[0019]
Here, that the insulating material is transparent or translucent means that the transparency of the insulating material is 20 to 80%. And this transparency measures the transmission intensity of the visible light emitted from the other surface while irradiating the visible light to one surface of a plate-shaped sample made of the same material as the insulating material and having the same thickness as the FFC. A value obtained by dividing the transmission intensity by the irradiation intensity is shown as a percentage.
[0020]
In addition, it is preferable that the thickness of the insulating material covering the wide surface of each conductor, that is, the surface including the width direction and the longitudinal direction is 0.05 to 0.5 mm. This is because when the thickness of the insulating material is 0.05 to 0.5 mm, the insulating property of the insulating material is ensured, and the FFC has good bending workability.
The FFC 10 can be manufactured by a known method. For example, an insulating material is put into a single-screw extruder equipped with a crosshead and melted, and when the two conductors pass in parallel in the crosshead, the two materials are melted by the molten material. The conductor may be extrusion coated. In this case, the shape and size of the FFC are defined by the shape and size of the crosshead.
[0021]
The piercing-type connection terminal disclosed in Japanese Patent Application Laid-Open No. 11-144780 was installed and mounted on the above-described FFC 10 as follows. Specifically, as shown in FIG. 2, the piercing-type connection terminal 16 includes a flat portion 18 and three pairs of rising portions 20 provided on both side edges of the flat portion 18.
In the FFC 10, as schematically shown in FIG. 3, since the meandering in the width direction of the conductors 12 ₁ and 12 ₂ is large, the accuracy of the pitch between the conductors is extremely low at about ± 0 to 0.3 mm. , only the position of the end conductors ₁₂ 1 exposed and the surface, 12 _second end surface of the FFC 10, it is difficult to guess the position of each conductor ₁₂ 1, 12 ₂ in the insulating material 14.
[0022]
Therefore, To illustrate the case of mounting the piercing connecting terminal 16 to conductor 12 ₂ of FFC 10, prior to the work piercing the connecting terminal 16 to confirm the position of the conductor 12 ₂ of the insulating material 14. More specifically, visible light is irradiated from below along the thickness direction around the place where the piercing-type connection terminal 16 of the FFC 10 is mounted, and the visible light emitted from the upper side of the FFC 10 through the insulating material 14 is emitted. by detecting with sensors and CCD, to confirm the position of the conductor 12 ₂ of the insulating material 14. Then, to pass through the FFC 10 includes a conductor 12 ₂ position has been confirmed, was pierced rising portion 20 of the piercing connecting terminal 16 from the lower side of the FFC 10. Thereafter, the rising portion 20 that protrudes above the FFC 10, is bent so as to draw a arc, piercing the tip of the rising portion 20 from the upper side of the FFC 10 to the conductor 12 ₂ through an insulating material 14, and mounting the connecting terminal 16 to the FFC 10 (See FIGS. 4 and 5).
[0023]
FFC10 is thus with piercing connecting terminals 16 mounted respectively to the conductors 12 _1, 12 ₂ in the permitted the realization of reliable electrical connection between the printed circuit board.
As described above, the conductor of the FFC 10 is a rolled flat conductor manufactured by a rolling method, and has higher productivity and is less expensive than a conductor manufactured by a slit method. In addition, FFC 10 is manufactured under high productivity by an extrusion coating method and is very inexpensive.
[0024]
Further, in the FFC 10, since the material of the insulating material is transparent or translucent, when the piercing-type terminal is attached to the FFC, the material penetrates the insulating material of the FFC without using X-rays and the like harmful to the human body. By measuring the visible light to be reflected or the visible light reflected by the FFC conductor using an optical sensor or a CCD, the position of the conductor in the insulating material can be reliably detected.
[0025]
Therefore, the FFC 10 is manufactured by extrusion-coating a rolled flat conductor, and is equipped with an inexpensive piercing-type connection terminal capable of obtaining reliable electrical and mechanical connection performance even if the pitch between conductors is low. Can be.
When the FFC 10 is routed in a place where light is incident, it is possible to prevent light deterioration of the insulating material of the FFC 10 by laying the FFC 10 inside a protective material having a light shielding property. As a method of such wiring, for example, a method of winding a self-fusing tape around the outer periphery of the FFC 10 can be mentioned. As the self-bonding tape, for example, Fco Tape No. 2 manufactured by Fco Co., Ltd. may be mentioned.
[0026]
The present invention is not limited to the above-described embodiment, and can be appropriately changed. For example, the number of conductors is not limited to two and may be three or more.
[0027]
【The invention's effect】
As is clear from the above description, the flexible flat cable of the present invention has a rolled flat conductor extruded with a transparent or translucent insulating material, and can be manufactured under high productivity and is inexpensive. .
Further, according to the flexible flat cable installation method of the present invention, it is possible to securely mount the piercing-type connection terminal on the flexible flat cable whose transparent or translucent insulating material is extrusion-coated with a flat rolled conductor.
[Brief description of the drawings]
FIG. 1 is a perspective view of a flexible flat cable (FFC) according to an embodiment of the present invention.
FIG. 2 is a perspective view of a piercing connection terminal mounted on the FFC of FIG. 1;
FIG. 3 is a view for explaining meandering of conductors in the FFC of FIG. 1;
4 is a partially enlarged perspective view showing a state in which the piercing type connection terminal of FIG. 3 is mounted on the FFC of FIG. 1;
FIG. 5 is a sectional view taken along the line VV of FIG. 4;
[Explanation of symbols]
12 ₁ , 12 ₂ Flat conductor 14 Insulating material

Claims (2)

In a flexible flat cable including a plurality of flat conductors spaced apart and arranged in parallel in the width direction and an insulating material covering the plurality of flat conductors collectively,
The flexible flat cable, wherein each of the plurality of flat conductors is a flat conductor obtained by rolling a conductor having a circular cross-sectional shape, and the insulating material is transparent or translucent. A method of constructing a flexible flat cable for connecting a piercing type connection terminal to the flexible flat cable according to claim 1,
By irradiating light from one side of the flat cable and receiving transmitted light on the other side, the position of the flat conductor in the flat cable is confirmed and the piercing-type terminal is pierced. Flexible flat cable construction method.

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