JPH05259587A - Film carrier - Google Patents

Abstract

PURPOSE:To prevent disconnection, cracks, and deformation like twist and bending when a conductor pattern is bent, and form the conductor pattern of a bending part with freedom, by arranging a plurality of small holes on an insulative film of the bending part. CONSTITUTION:An insulative film 2 wherein a plurality of small holes 5 are punched is used. When a film carrier is bent, the whole bent part forms a gentle arc, so that the bending stress is dispersed throughout the whole hole area 2a for bending work, and generation of cracks in a lead or the like is prevented. The small holes are not always punched in a lattice type, but a zigzag type or the like may be arbitrarily used. The bending radius can be adjusted by selecting small hole working pitches p1, p2, the small hole diameter (d), etc. Since a conductor pattern 1 is retained by the insulative film punched in a lattice type, short-circuit is not generated when the conductor pattern 1 is obliquely drawn. Hence the freedom of conductor pattern formation is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film carrier, and more particularly to a film carrier capable of effectively preventing disconnection, cracking, bending, etc. of a conductor pattern due to bending.

[0002]

2. Description of the Related Art Conventionally, a film carrier for a liquid crystal driver or the like which is bent and used has a slit in the bent portion of the insulating film in order to reduce springback due to the elasticity of the insulating film and the adhesive.

A top view of the film carrier having slits in the bent portion is shown in FIG. 1 (a), and a sectional view thereof is shown in FIG. 1 (b). In the figure, 1 is a conductor pattern, 2 is an insulating film (base film),
Reference numeral 3 denotes a slit, and A denotes a bent portion.

As shown in FIG. 1, when the bent portion A having the slit 3 is bent, stress is concentrated on the boundary between the conductor pattern 1 and the insulating film 2 at the edge portion of the slit, and the conductor pattern 1 is damaged. There is a problem that cracks easily occur and the wire is broken in some cases.

Further, since the conductor pattern 1 is exposed at the slit 3 at a distance of about 0.5 to 1 mm,
Especially at fine pitches, deformation such as twisting or bending of the leads is likely to occur. Furthermore, it is desirable that the width and interval of the slits are small, but it cannot be reduced due to the limitation of the shape of the mold.

As one means for solving such a problem, a film carrier having a bent portion coated with a resin has been proposed. A top view of this film carrier is shown in FIG.
FIG. 2A shows a sectional view thereof, and FIG. 2B shows a sectional view thereof. In the figure, the same reference numerals as those in FIG. 1 denote the same components, and 4 is a coating resin.

As shown in the figure, a coating resin 4 is provided on the front surface and the back surface of the conductor pattern of the bent portion, whereby the strength of the bent portion is reinforced to prevent the conductor pattern 1 from being broken. It is a thing.

As another means, the insulating film to be slit is removed by etching to have a thickness of about half.
Attempts have been made not only to improve the bendability, but also to maintain the strength of the bent portion constant and prevent the conductor pattern 1 from being broken.

However, any of these means
Compared with the method of manufacturing a film carrier in which the conductor pattern of the slit as shown in FIG. 1 is exposed, the number of steps is significantly increased, resulting in high cost, which is difficult to economically and productivity.

Further, in the past, the conductor pattern on the slit was able to form only a conductor pattern perpendicular to the bending direction in order to prevent a short circuit of the lead at the time of bending, and lacked flexibility in forming the conductor pattern. ..

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and can effectively and easily prevent disconnection, cracking, twisting, bending, etc. due to bending of a conductor pattern. At the same time, it is an object of the present invention to provide a film carrier in which the conductor pattern of the bent portion can be formed with a degree of freedom.

[0012]

The above object of the present invention is achieved by providing a plurality of small holes in the insulating film of the bent portion.

That is, the film carrier of the present invention is
It is characterized in that it has an insulating film and a conductor pattern formed of a metal foil on the insulating film, and that a plurality of small holes are provided in the insulating film at the bent portion.

The insulating film and the metal foil used in the present invention are not particularly limited, and ordinary ones can be used. Examples of the insulating film include a polyimide resin, a glass epoxy resin, a polybutylene terephthalate resin, a polyester resin, and the like, but the polyimide resin is generally used in consideration of workability and characteristics. The metal foil may be any one having conductivity, but a copper foil is generally used.

In the present invention, a plurality of small holes are provided in the insulating film at the bent portion, but no special process is required.
That is, the insulating film may be punched by punching a plurality of small holes in the bent portion together with holes such as device holes using a punching die.

A metal foil such as a copper foil is adhered to the insulating film having a plurality of small holes in such a bent portion through an adhesive if necessary, and the metal foil is exposed, developed and etched by a photoetching method. A film carrier is manufactured by forming a predetermined conductor pattern by applying a solder resist and forming a plating film on the metal surface, if desired.

A top view of such a film carrier of the present invention is shown in FIG. 3 (a), and a sectional view thereof is shown in FIG. 3 (b). In the figure, the same reference numerals as those in FIG. 1 indicate the same parts, 2a is a processing hole area for bending the insulating film, and 2b is the other area of the insulating film.

An enlarged view of the bending hole area 2a of the insulating film is shown in FIGS. 4 (a) to 4 (c). In the figure, 5 is a small hole, p1 and p2 are small hole machining pitches,
d indicates the small hole diameter.

As shown in FIG. 4 (a), a plurality of small holes 5 are punched out in a grid-like arrangement. By using such an insulating film 2, when the film carrier is bent, the bending portion bends in a gentle arc as shown in FIG. 3B, so that the bending stress is reduced. Processing hole area 2a for bending
It is also possible to avoid cracks in the leads, etc., as compared with the conventional method in which stress is concentrated on the edges of the slits, which is dispersed over the entire surface. The punching arrangement of the small holes is not limited to the lattice shape, and the arrangement shown in FIG.
It is arbitrary such as a staggered shape as shown in (b).

The bending radius is the small hole machining pitch p1, p
2 or the small hole diameter d. Further, the bending radius becomes smaller, and the processing hole area for bending 2a
When stress is concentrated on the boundary between the other area 2b and the other area 2b, the small hole machining pitches p1 to p2 and the small hole diameter d at the central portion and the boundary portion of the bending hole area 2a.
It can be solved by adjusting the etc. In FIG. 4C, the small hole diameter d is variously adjusted.

Conventionally, the conductor pattern of the bent portion is provided perpendicularly to the bending direction, as shown in FIG. 5A, in order to prevent a short circuit of the lead at the time of bending.

However, in the film carrier of the present invention, the conductor pattern 1 in the obtained bending hole area 2a may be provided with the conductor pattern 1 perpendicular to the bending direction as shown in FIG. 5 (a). However, even if the conductor pattern 1 is slanted around as shown in FIG. 5B, the conductor pattern 1 is supported by the insulating film punched out in a grid pattern, so that there is no fear of short-circuiting and the degree of freedom in forming the conductor pattern is improved. ..

Further, as shown in FIG. 5 (b), by diagonally routing, the routing pitch of the L portion is increased, which not only contributes to improvement in yield, reliability, etc., but also shortens the distance of the L portion. However, it is possible to reduce the size of the film carrier.

[0024]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 A 75 μm polyimide film (Ubilex) was used as an insulating film, and the bent portion was φ1.0 m.
Punching was carried out with round holes having a diameter of m and a hole pitch of 2.0 mm. The punching arrangement of the small holes was a grid pattern. A copper foil was laminated on this insulating film with an epoxy adhesive, and then exposed, developed and etched by a photoetching method to form a predetermined conductor pattern, which was used as a test sample.

At this time, the line width of the bent portion is 100 μm,
The pitch was 200 μm, and the width of the film carrier was 35 mm. The film carrier thus obtained was evaluated by the following method.

First, one product is cut out into the same size as when the film carrier is mounted, one end of the bent portion is fixed with a jig, and the bent portion is bent until it is bent by 180 °, cracks occur, or leads are inserted. It was reciprocated until it peeled off, and the number of times was evaluated. As a result, this film carrier was 34 times.

Example 2 Except that the bent portion of the insulating film was punched with a round hole having a diameter of 1.0 mm and a hole pitch of 1.5 mm, and the punching arrangement of the small holes was made into a staggered pattern, the same material and process as in Example 1 were used. I made a film carrier with. Bending test Example 1
As a result, the number of times was 52 times.

Example 3 Except that the bent portion of the insulating film was punched with a round hole having a diameter of 0.5 mm and a hole pitch of 1.0 mm, and the punching arrangement of the small holes was made into a staggered pattern, the same material and process as in Example 1 were used. I made a film carrier with. Bending test Example 1
As a result, the number of times was 61 times.

COMPARATIVE EXAMPLE 1 The bent portion of the insulating film has a width of 0.8 mm and a length of 20 m.
A film carrier was prepared by using the same materials and steps as in Example 1 except that punching was performed with slit holes having a pitch m of 2 mm. As a result of performing the bending test in the same manner as in Example 1, the number of times was 12 times.

[0031]

As described above, with the film carrier of the present invention, disconnection due to bending of the conductor pattern,
Deformation such as cracking, twisting, and bending can be effectively and easily prevented, and the conductor pattern of the bent portion can be formed with a degree of freedom.

[Brief description of drawings]

FIG. 1 is a top view and a cross-sectional view showing an example of a conventional film carrier.

FIG. 2 is a top view and a cross-sectional view showing another example of a conventional film carrier.

FIG. 3 is a top view and a cross-sectional view showing an example of the film carrier of the present invention.

FIG. 4 is an enlarged top view of a processed hole area for bending an insulating film.

FIG. 5 is a top view showing a conductor pattern formation state of a bent portion.

[Explanation of symbols]

1: conductor pattern, 2: insulating film, 2a: processed hole area for bending insulating film, 5: small hole.

Claims (1)

[Claims] 1. A film carrier comprising an insulating film and a conductor pattern formed of a metal foil on the insulating film, wherein the insulating film at the bent portion is provided with a plurality of small holes.