JP2002025641A - Surface-mount flexible flat cable and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a novel surface-mount flexible flat cable, capable of surely manufacturing a high-detail surface-mount flexible flat cable at a low cost. SOLUTION: Conductors 1 are sandwiched between insulating films 2 made of polyethylene terephthalate with a nonflammable polyester adhesive while the conductors 1 are bonded with a conductive adhesive 6 to terminals 4 of an integrated circuit 3 mounted on surfaces of the conductors 1 by using bore holes bored by laser as contact parts. This dispenses with expensive film for the insulating film 2 and dispenses with joining the conductors 1 to the terminals 4 by soldering. Therefore, the high-detail surface-mount FCC can be easily provided at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible flat cable used for a wiring of a movable portion of an electronic / electric device or a jumper wire between circuits, and more particularly to a surface mount flexible having an integrated circuit integrally mounted on the surface thereof. The present invention relates to a flat cable and a method for manufacturing the flat cable.

[0002]

2. Description of the Related Art Conventionally, such a flexible flat cable (hereinafter referred to as FFC) is composed of a plurality of solder-plated conductors 1, 1... Arranged in parallel as shown in FIG. Sandwich it from above and below with 2,
It is a tape-shaped electric wire obtained by laminating with a hot roll, and its thickness is generally very thin, generally about 0.1 to 0.3 mm.

[0003] Such an FFC has not only flexibility but also excellent bending resistance.
The number of cases where a D-ROM pickup unit wiring is used as a substitute for a flexible printed circuit board has been rapidly increasing.
The development of a high-detail FFC with a gap of 0.1 mm and a gap of 0.1 mm) is also in progress.

Further, such an FFC and an integrated circuit disposed on a substrate are generally joined via a connector provided on the substrate. As shown in FIGS. 6 and 7, so-called surface-mounted FFCs, in which the integrated circuit 3 is directly mounted on the surface of the FFC, have also appeared in order to cope with miniaturization of equipment.

[0005]

When mounting the integrated circuit 3 on the surface of the FFC, as shown in FIGS. 8 and 9, the conductors 1, 1,... In order to join between them, perforations 5, 5,... Are previously formed at predetermined positions on the plastic film 2 by pressing or the like, and contacts are formed so as to expose the conductors 1, 1,. Each terminal in 4, 5, ...
Are inserted and brought into contact with each other to join them together by soldering.

However, when adopting such a manufacturing method, it is necessary to use a material having excellent heat resistance as the plastic film 2 and the adhesive, for example, a resin such as a polyimide form with an epoxy adhesive. Since these resins are generally expensive, there is a disadvantage that the material cost increases as the overall length of the FFC increases.

For this reason, at present, as shown in FIGS. 10 and 11, only the plastic film 2 where the integrated circuit 3 is mounted is made of expensive polyimide with an epoxy adhesive, and the other parts are inexpensive polyester adhesive. Polyethylene terephthalate is used, but when using different kinds of films like this, it is necessary to bond the two each time by soldering, and instead there is a problem that the number of manufacturing processes increases and it is difficult to reduce costs. .

On the other hand, when the multi-terminal integrated circuit 3 is mounted on the surface of the FFC, the width of the FFC is determined by the conductors 1, 1 of the FFC.
The pitch is multiplied by the number of terminals of the integrated circuit 3 (F
FC width dimension = FFC conductor pitch x number of integrated circuit terminals).
Therefore, the multi-terminal integrated circuit 3 for narrow space equipment
It is necessary to reduce the pitch (high detail) of the FFC in order to surface-mount the contact. However, as described above, the contact portion (perforation) of the plastic film 2 that joins the terminals of the integrated circuit 3
Is formed by press perforation before lamination, so that there is a problem that it is difficult to stably form a contact in the case of a high-detail FFC having a pitch of 0.5 mm or less.

The present invention has been devised in order to effectively solve such a problem, and an object of the present invention is to provide a highly detailed surface-mounted flexible flat cable and a low-cost and reliable surface-mounted flexible flat cable. The present invention provides a method for manufacturing a novel surface-mount flexible flat cable that can be manufactured at a low cost.

[0010]

In order to solve the above-mentioned problems, according to the present invention, one or more parallel conductors are sandwiched by an insulating film with an adhesive and terminals are provided on the surface thereof. In a surface mount flexible flat cable on which an integrated circuit is mounted, polyethylene terephthalate is used as the insulating film, a flame-retardant polyester adhesive is used as the adhesive, and the terminal between the terminal of the integrated circuit and the conductor is used. Are bonded with a conductive adhesive using the perforations of the insulating film perforated by a laser as contact points.

That is, the present invention uses an inexpensive polyethylene terephthalate film with a polyester adhesive, which has been conventionally used as an insulating film with an adhesive, and forms a contact portion by perforating the film with a laser. At the same time, the terminals of the integrated circuit and the conductor are joined at the contact portions with a conductive adhesive.

Accordingly, it is not necessary to use an expensive polyimide film with an epoxy adhesive as in the prior art, so that the material cost can be greatly reduced. Also,
Since the contact portion is formed by piercing with a laser, it is possible to easily perform high-precision piercing.
A stable contact can be created even for a high-detail FFC with a pitch of 5 mm or less.

A specific method for manufacturing such a surface mount flexible flat cable is described in claim 2 below.
As shown in the figure, a single or a plurality of parallel conductors are sandwiched between a polyethylene terephthalate film coated with a flame-retardant polyester adhesive in advance, and the surface of the polyethylene terephthalate film is irradiated with a laser to irradiate the inside thereof. Perforate so that the conductor is exposed, and then
The terminal of the integrated circuit is inserted into the perforation, and this is joined to the conductor side inside with a conductive adhesive. By adopting this manufacturing method, a highly detailed surface having a pitch of 0.5 mm or less can be obtained. Even a mounted flexible flat cable can be manufactured at low cost and with high accuracy.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a plan view showing an embodiment of a surface-mounted flexible flat cable (hereinafter, referred to as a surface-mounted FFC) according to the present invention, and FIG. 2 is a side view thereof.

As shown, this surface mount FFC is:
The insulating films 2, 2 sandwiching a plurality of conductors 1, 1,... Arranged in parallel from above and below are made of inexpensive polyethylene terephthalate, and a flame-retardant polyester-based adhesive is used as the adhesive, and is integrated. The terminal 4 of the circuit 3 and the conductor 1 are joined by a conductive adhesive 6 with a perforation 5 perforated by a laser as a contact portion, and has a highly detailed structure with a pitch of 0.5 mm or less.

As such a surface-mounted FFC, for example, as shown in FIG. 4, first, conductors 1, 1,... Are made of a pair of polyethylene terephthalate coated with a flame-retardant polyester adhesive. Film 2,2
After that, a high-density laser beam, for example, a CO ₂ laser or Y
Irradiate with AG laser. Then, as shown in FIG.
The exposed portions of the resin evaporate to expose and expose the conductors 1, 1,... To form perforations 5, 5,. Next, as shown in FIG. 4, if the contact portions are formed in this way, the conductive adhesives 6, 6,... Are attached to the tips of the terminals 4, 4,. Terminal 4,
4 are inserted into the perforations 5, 5 and joined to the exposed conductors 1, 1.
Then, by heating in a reflow furnace at a low temperature (110 ° C.) and bringing the whole into close contact, it is possible to easily and inexpensively obtain the above-described high-detail surface mount FFC.

That is, in the method of the present invention, first, a laser beam is used as a method for forming the perforations 5, 5... 0.3m was difficult
Even a contact portion having an m pitch (a conductor width of 0.2 mm and a gap of 0.1 mm) can be easily and accurately formed. Second, since the integrated circuit 3 is attached by using a conductive adhesive 6, 6,... Instead of using solder as in the related art,
Since heat resistance is no longer required for the insulating films 2 and 2, it is not necessary to use expensive polyimide with an epoxy adhesive, and it is possible to use an inexpensive resin such as polyethylene terephthalate as it is. Even a high-detail surface mount FFC with a pitch of 0.5 mm or less, which has been increasingly used recently, can be easily and inexpensively manufactured.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a solder-plated rectangular soft copper wire (width 0.3 mm × thickness 0.05 mm, pitch 0.5) was used as an FFC conductor.
mm, 40 cores), a flame-retardant polyester (thickness: 35 μm) -attached polyethylene terephthalate (thickness: 25 μm) film was used as an insulating film, and an IC having 40 terminals was prepared as an integrated circuit.

Next, after this solder-plated rectangular soft copper wire is sandwiched between the insulating films, a CO ₂ laser is irradiated onto each of the solder-plated rectangular soft copper wires to easily form fine holes having an outer diameter of 0.1 mm. I was able to.

Thereafter, a conductive adhesive (base agent / flame-retardant polyester (softening temperature of 100) is applied to each terminal of the integrated circuit.
℃), conductor / Ni filler (φ20μm)), and then bonded to each solder-plated rectangular soft copper wire. As a result, each solder-plated rectangular soft copper wire and the terminal were electrically connected securely.
A high-detail surface-mount FFC with a pitch of 0.3 mm was easily obtained.

[0022]

In summary, according to the present invention, a laser is used as a method for perforating an insulating film, and a conductive adhesive is used as a bonding method.
C can be produced reliably at low cost.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a surface mount flexible flat cable according to the present invention.

FIG. 2 is a side view showing one embodiment of the surface-mount flexible flat cable according to the present invention.

FIG. 3 is a plan view taken along line AA in FIG. 2;

FIG. 4 is a process chart showing one embodiment of the method of the present invention.

FIG. 5 is a perspective view showing an example of a conventional flexible flat cable.

FIG. 6 is a plan view showing an example of a conventional surface mount flexible flat cable.

FIG. 7 is a side view showing an example of a conventional surface mount flexible flat cable.

FIG. 8 is an enlarged sectional view taken along line AA in FIG. 6;

FIG. 9 is an explanatory view showing an example of a method for manufacturing a conventional surface-mount flexible flat cable.

FIG. 10 is a plan view showing an example of a conventional surface mount flexible flat cable.

FIG. 11 is a side view showing an example of a conventional surface mount flexible flat cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor 2 Insulating film 3 Integrated circuit 4 Terminal 5 Perforation 6 Conductive adhesive

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsutomu Komori 4-10-1, Kawajiri-cho, Hitachi-shi, Ibaraki F-term in Hitachi Cable Processing Co., Ltd. (Reference) 5E077 BB05 BB28 DD04 EE02 HH01 HH04 HH10 JJ30 5E085 BB05 BB26 CC03 DD05 EE05 GG22 GG33 HH34 JJ38 JJ50 5E319 AA02 AB01 AC03 CC03 CC61 CD61 CD60

Claims (2)

[Claims] 1. A surface-mounted flexible flat cable in which one or a plurality of parallel conductors is sandwiched by an insulating film with an adhesive and an integrated circuit with terminals is mounted on the surface thereof, wherein polyethylene terephthalate is used as the insulating film. A flame-retardant polyester-based adhesive is used as the adhesive, and the terminal of the integrated circuit and the conductor are joined with a conductive adhesive as a contact portion using the perforation of the insulating film perforated by a laser as a contact portion. A surface mount flexible flat cable characterized by the following: 2. A single or a plurality of parallel conductors are sandwiched between a polyethylene terephthalate film coated with a flame-retardant polyester adhesive in advance, and a laser is applied to the surface of the polyethylene terephthalate film to irradiate a conductor inside the polyethylene terephthalate film. Manufacturing a surface-mount flexible flat cable, characterized in that a hole of an integrated circuit is inserted into the hole so as to be exposed, and the terminal of the integrated circuit is then bonded to a conductor side inside the hole with a conductive adhesive. Method.