JP2014154244A - Method for manufacturing a shield-clad flexible flat cable and shield-clad flexible flat cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a shield-clad flexible flat cable capable of accommodating pitch reduction attempts and of obtaining a sufficient connection strength between a conductor and a shield layer without entailing process convolutions; and the shield-clad flexible flat cable.SOLUTION: The provided method includes a first step of removing insulating films 12a and 12b of a flexible flat cable 11 with a laser so as to bare the conductor 13a thereof serving as a ground wire and a second step of forming a shield layer 14 around the flexible flat cable 11 and then electrically connecting the shield layer 14 and the bared conductor 13a, whereas the insulating films 12a and 12b are removed with a COlaser at the first step, whereas the adhesive layer 15 underneath the former is removed via a laser work, mechanical polish, or chemical polish.

Description

  The present invention relates to a method for manufacturing a shielded flexible flat cable and a shielded flexible flat cable.

  BACKGROUND ART Shielded flexible flat cables, which are provided with countermeasures against electromagnetic interference (EMI) caused by unwanted radiation, etc., are used in various fields such as in-vehicle cables.

  As a method of manufacturing this shielded flexible flat cable, a laminate coating with an insulating film is carried out with a dummy wire superimposed on a conductor to be a ground (GND) wire, and the insulating film positioned on the conductor after the lamination coating is applied to the dummy wire. The conductor is then peeled off to form a shield layer, and then a shield layer is formed around the flexible flat cable, and the shield layer and the exposed conductor are electrically connected. Is known to ensure electrical connection (ground connection) (see, for example, Patent Document 1).

  However, in this manufacturing method, in order to achieve single-ended transmission, if an attempt is made to secure a ground connection every other core, an insulating film positioned on the conductor that becomes the signal line arranged between the conductors that become the ground line Both of them may be peeled off, and in particular, it has been difficult to cope with the narrow pitch due to the miniaturization of equipment and the space saving of wiring.

  In addition, there is a demand to apply gold plating to the conductor end, assuming a connector for a flexible flat cable with shield, etc., but there is no variation in the plating thickness of each conductor, and gold is applied only to the end of the conductor. In order to perform the plating process, the masking process must be performed on portions other than the exposed end portions of the conductors, which complicates the process and adversely affects the manufacturing cost.

  Other methods of manufacturing a shielded flexible flat cable include a method of securing a ground connection after laminating and covering a conductor with a pre-perforated insulating film, and excimer laser or YAG laser for insulating film of a flexible flat cable. A method is known in which a ground connection is ensured after a conductor is exposed by itself (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 2004-87312 JP 2004-93178 A

  However, in the method of making holes in the insulating film in advance, since the alignment between the holes of the insulating film and the conductor is essential, the narrower the pitch between the centers of the conductors, the higher the alignment accuracy. Therefore, technical measures are difficult and there is a concern about an increase in manufacturing costs.

  Further, in the method of exposing a conductor using an excimer laser or a YAG laser alone, for example, when the pitch between the centers of the conductors is 0.5 mm or less, it becomes impossible to accurately expose only a specific conductor. Since it is difficult to sufficiently remove the insulating film on the conductor and the adhesive layer underneath it, processes such as ultrasonic bonding and spot welding are required to maintain sufficient connection strength between the conductor and the shield layer. A separate process is required and the process is complicated.

  Accordingly, an object of the present invention is to provide a shielded flexible flat cable that can cope with a narrow pitch and can obtain a sufficient connection strength between the conductor and the shield layer without complicating the process. And a shielded flexible flat cable.

The present invention created to achieve this object includes a first step of removing the insulating film of the flexible flat cable with a laser to expose a conductor to be a ground wire, and a shield layer around the flexible flat cable. And a second step of electrically connecting the shield layer and the exposed conductor. In the first step, the insulating film is removed by a CO ₂ laser, A method for manufacturing a shielded flexible flat cable in which an adhesive layer is removed by laser processing, mechanical polishing, or chemical polishing.

  The flexible flat cable is arranged such that a plurality of conductors are arranged in parallel on the adhesive surface of the first insulating film on which an adhesive layer is formed, and the conductor is sandwiched between the first insulating film and the flexible flat cable. The adhesive surface of the second insulating film on which the layer is formed is preferably bonded to the adhesive surface of the first insulating film.

  In the first step, at least a part of either one or both of the first insulating film and the second insulating film of the flexible flat cable may be removed by a laser.

In the first step, the first insulating film or the second insulating film may be removed by a CO ₂ laser, and the underlying adhesive layer may be removed by laser processing, mechanical polishing or chemical polishing.

  The pitch between the centers of the conductors is preferably 0.5 mm or less.

  The first insulating film and the second insulating film may be made of a plastic film.

  The adhesive layer may be formed of an adhesive having a polyester resin or an olefin resin as a main raw material.

  The adhesive may contain an additive or a flame retardant.

  Prior to the first step, a step of plating the terminal portion of the conductor may be further provided.

  Moreover, this invention is a flexible flat cable with a shield manufactured by the manufacturing method of the said flexible flat cable with a shield.

  According to the present invention, manufacture of a shielded flexible flat cable that can cope with a narrow pitch and can obtain a sufficient connection strength between the conductor and the shield layer without complicating the process. A method and shielded flexible flat cable can be provided.

It is a figure explaining the 1st process in the manufacturing method of the flexible flat cable with a shield concerning this embodiment, (a) is a perspective view and (b) is an AA line sectional view. It is a figure explaining the 1st process in the manufacturing method of the flexible flat cable with a shield concerning this embodiment, (a) is a perspective view and (b) is an AA line sectional view. It is a figure explaining the 2nd process in the manufacturing method of the flexible flat cable with a shield concerning this embodiment, (a) is a perspective view and (b) is an AA line sectional view. The CO ₂ laser is a photograph showing the appearance of a flexible flat cable upon removal of the insulating film, (a) shows the photograph of the whole, photograph of the end of (b) a conductor, (c) the conductor This is a photo showing the middle part. It is the photograph which shows the external appearance of a flexible flat cable when an insulating film is removed by a FAYb laser (CW oscillation), (a) is the photograph which copied the whole, (b) The photograph which copied the edge part of a conductor, (c) Is a photograph showing the middle part of the conductor. It is the photograph which shows the external appearance of the flexible flat cable when an insulating film is removed by a FAYb laser (pulse oscillation), (a) is a photograph showing the whole, (b) A photograph showing the end of the conductor, (c) Is a photograph showing the middle part of the conductor.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1 to FIG. 3, the method of manufacturing the shielded flexible flat cable 10 according to the present embodiment removes the insulating films 12 a and 12 b of the flexible flat cable 11 with a laser to provide a conductor 13 a that becomes a ground line. A first step of exposing, and a second step of forming the shield layer 14 around the flexible flat cable 11 and electrically connecting the shield layer 14 and the exposed conductor 13a. In this process, the insulating films 12a and 12b are removed by a CO ₂ laser, and the underlying adhesive layer 15 is removed by laser processing, mechanical polishing or chemical polishing.

  The flexible flat cable 11 has a plurality of conductors 13a and 13b arranged in parallel on the adhesive surface of the first insulating film 12a on which the adhesive layer 15 is formed, and the conductor 13a and the first insulating film 12a. The adhesive surface of the second insulating film 12b on which the adhesive layer 15 is formed is bonded to the adhesive surface of the first insulating film 12a so as to sandwich 13b.

  Specifically, the insulating films 12a and 12b and the conductors 13a and 13b are placed so that the conductors 13a and 13b are positioned between the adhesive surface of the first insulating film 12a and the adhesive surface of the second insulating film 12b. The flexible flat cable 11 is formed by unifying the insulating films 12a and 12b and the conductors 13a and 13b by rolling out from the feeder and rolling with a rolling mill while maintaining these positional relationships.

  The first insulating film 12a and the second insulating film 12b are made of a plastic film such as polyethylene terephthalate (PET).

  The plurality of conductors 13a and 13b includes a conductor 13a serving as a ground line and a conductor 13b serving as a signal line. The pitch between the centers of the conductors 13a and 13b is set to 0.5 mm or less, for example, in order to cope with a narrow pitch.

  In the present embodiment, in order to realize single-ended transmission, conductors 13a serving as ground lines and conductors 13b serving as signal lines are alternately arranged. However, the arrangement of the conductors 13a and 13b is particularly limited. Instead, it may be changed according to a transmission method (for example, differential transmission) to be realized or other circumstances.

  The adhesive layer 15 is formed of an adhesive using a polyester resin or an olefin resin as a main raw material, and the adhesive may contain an additive or a flame retardant.

  In the first step, at least a part of one or both of the first insulating film 12a and the second insulating film 12b of the flexible flat cable 11 is removed by laser, but the pitch between the centers of the conductors 13a and 13b is reduced. In the case of a narrow width of 0.5 mm or less, the insulating films 12a and 12b are prevented from melting over a wide range, and in order to avoid contact between the conductor 13a and the conductor 13b or contact between the conductor 13b and the shield layer 14, the insulating film 12a Therefore, it is necessary to select a laser capable of performing higher-precision processing on 12b.

Therefore, in the present embodiment, the first insulating film 12a or the second insulating film 12b is removed by a CO ₂ laser (see FIG. 1), and the underlying adhesive layer 15 is laser processed, mechanically polished, or chemically polished. It is made to remove (refer FIG. 2).

Since the CO ₂ laser has a high absorption rate in the insulating films 12a and 12b, and the insulating films 12a and 12b can be processed with high accuracy, the CO ₂ laser can be used to connect the centers of the conductors 13a and 13b. Even if the pitch is 0.5 mm or less, processing can be performed without problems.

Since the CO ₂ laser has a low absorption rate in the adhesive layer 15, it is difficult to remove the insulating films 12a and 12b and the underlying adhesive layer 15 with only the CO ₂ laser (FIG. 1B). reference).

Therefore, in the method of manufacturing the shielded flexible flat cable 10 according to the present embodiment, the adhesive layer 15 is removed by laser processing, mechanical polishing, or chemical polishing after the insulating films 12a and 12b are removed by the CO ₂ laser. Yes.

  When laser processing is selected, a YAG laser that has a high absorption rate in the adhesive layer 15 and can effectively remove the adhesive layer 15 can be used, and when mechanical polishing is selected, A polishing process using a brush can be employed.

  As a result, the adhesive layer 15 on the surface of the conductor 13a can be sufficiently removed, and the adhesive layer 15 does not remain on the surface of the conductor 13a after the first step. It is possible to realize sufficient connection strength.

  Therefore, in the second process, it is not necessary to perform a process such as ultrasonic bonding or spot welding in order to maintain a sufficient connection strength between the conductor 13a and the shield layer 14, and the process is simplified as compared with the conventional process. Can be achieved.

  The shield layer 14 is formed by winding a conductive tape made of a conductive material such as aluminum around the flexible flat cable 11.

  Since the conductive adhesive layer 16 is formed on the conductive tape, when the conductive tape is wound around the flexible flat cable 11, the exposed conductor 13 a and the shield layer 14 are interposed via the conductive adhesive layer 16. It is electrically connected to ensure ground connection (see FIG. 3).

  In the present embodiment, the conductor 13a serving as the ground line is exposed over the entire length, but only a part of the conductor 13a other than the terminal portion may be exposed.

  Note that it is preferable to expose the conductor 13a while avoiding the bent portion when the wiring is used. Thereby, it is possible to effectively prevent the conductor 13a and the shield layer 14 from being peeled due to the stress applied during bending.

  The shielded flexible flat cable 10 can be manufactured by the above process.

As described so far, according to the present invention, the insulating films 12a and 12b are processed with high accuracy using a CO ₂ laser, and the underlying adhesive layer 15 is removed by another means. A method of manufacturing a shielded flexible flat cable 10 that can cope with a narrow pitch and can obtain sufficient connection strength between the conductor 13a and the shield layer 14 without complicated processes, and The shielded flexible flat cable 10 can be provided.

  In addition, you may make it further provide the process of plating to the terminal part of conductor 13a, 13b prior to a 1st process. Thereby, since a plating process can be performed without performing a masking process, a process can be simplified compared with the past and it can contribute greatly to the fall of manufacturing cost.

Hereinafter, the grounds for selecting the CO ₂ laser in order to remove the insulating films 12a and 12b will be described.

As shown in Table 1, the insulating films 12a and 12b were removed with three types of lasers, a CO ₂ laser, a FAYb laser (CW oscillation) and a FAYb laser (pulse oscillation), and the appearance was observed with a digital microscope.

As shown in FIG. 4, when the insulating film was removed with a CO ₂ laser, the insulating film was removed with high accuracy, and the conductor was clearly exposed.

  As shown in FIG. 5, when the insulating film was removed by the FAYb laser (CW oscillation), the insulating film was melted and high-precision processing could not be performed.

  As shown in FIG. 6, when the insulating film is removed by a FAYb laser (pulse oscillation), the middle part of the conductor is clearly exposed, but the insulating film melts at the end of the conductor, resulting in an edge. Could not be processed with high accuracy.

From the above results, in this embodiment, the CO ₂ laser was selected to remove the insulating film.

DESCRIPTION OF SYMBOLS 10 Flexible flat cable with shield 11 Flexible flat cable 12a 1st insulating film 12b 2nd insulating film 13a Conductor 13b used as a ground line Conductor 14 used as a signal line Shield layer 15 Adhesive layer 16 Conductive adhesive layer

Claims (10)

A first step of removing the insulating film of the flexible flat cable with a laser to expose a conductor to be a ground wire;
A second step of forming a shield layer around the flexible flat cable and electrically connecting the shield layer and the exposed conductor;
With
In the first step, the insulating film is removed by a CO ₂ laser, and the underlying adhesive layer is removed by laser processing, mechanical polishing or chemical polishing, and a method for producing a shielded flexible flat cable.   The flexible flat cable is arranged such that a plurality of conductors are arranged in parallel on the adhesive surface of the first insulating film on which an adhesive layer is formed, and the conductor is sandwiched between the first insulating film and the flexible flat cable. The method for producing a shielded flexible flat cable according to claim 1, wherein the adhesive surface of the second insulating film on which the layer is formed is bonded to the adhesive surface of the first insulating film.   The shielded flexible flat according to claim 2, wherein in the first step, at least a part of one or both of the first insulating film and the second insulating film of the flexible flat cable is removed by a laser. Cable manufacturing method. In the first step, the first insulating film or the second insulating film is removed by a CO ₂ laser, and the underlying adhesive layer is removed by laser processing, mechanical polishing or chemical polishing. The manufacturing method of the flexible flat cable with a shield of description.   The method for producing a shielded flexible flat cable according to any one of claims 2 to 4, wherein a pitch between the centers of the conductors is 0.5 mm or less.   The method for producing a shielded flexible flat cable according to any one of claims 2 to 5, wherein the first insulating film and the second insulating film are made of a plastic film.   The said adhesive layer is a manufacturing method of the flexible flat cable with a shield as described in any one of Claim 1 to 6 formed with the adhesive agent which made polyester resin or olefin resin the main raw material.   The said adhesive agent is a manufacturing method of the flexible flat cable with a shield of Claim 7 containing an additive or a flame retardant.   The manufacturing method of the flexible flat cable with a shield as described in any one of Claim 1 to 8 further equipped with the process of plating to the terminal part of the said conductor prior to a said 1st process.   A shielded flexible flat cable manufactured by the method for manufacturing a shielded flexible flat cable according to any one of claims 1 to 9.