JPH10261851A - Flexible substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the workability of an alignment of a flexible substrate, by a method wherein holes for alignment use, through which terminals for alignment are exposed on the other surface of the substrate, are provided in alignment exclusive terminal parts having no relationship with the electrical connection between external terminals and external connection terminals. SOLUTION: Terminals 3c exclusively for alignment, which are not connected with a wiring pattern, are respectively provided at both ends of external terminals 3b arranged on a flexible substrate 1 and holes 8 for alignment are respectively provided in the parts of the terminals 3c. The terminals 3c and terminals 6c exclusively for alignment can be seen from the side of the surface of a base film 2 through these holes 8, whereby the connection between the terminals 3b and connection terminals 6b using an anisotropic conductive bonding agent is never made in an incomplete state and as the surface, which is seen in an alignment of the substrate 1, of the substrate 1 and the surface, which is thermocompression-bonded or is temporarily fixed, of the substrate 1 can be made equal with each other, the structure of a device or a jig, which performs from the alignment to the thermocompression bonding or the temporary fixing, is not constituted into a complicated one. Accordingly, the workability of the alignment of the substrate 1 is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible substrate having a wiring pattern made of metal foil on one surface of the substrate.

[0002]

2. Description of the Related Art In recent years, a flexible substrate used for electronic equipment has a base material made of, for example, a polymer material film such as a polyimide resin, and a copper foil is adhered to one surface thereof, and the copper foil is etched. Wiring pattern is formed. A connection method for connecting such an external terminal of the flexible substrate to, for example, a connection terminal of a liquid crystal driving device is described in Japanese Utility Model Laid-Open Publication No. Hei 2-92963. Hereinafter, connection between an external terminal of a conventional flexible substrate and a connection terminal of a liquid crystal driving device will be described.

When connecting external terminals of a flexible substrate to connection terminals of a liquid crystal driving device, an anisotropic conductive adhesive is used. In this anisotropic adhesive, particles obtained by plating the periphery of a metal or a thermoplastic resin with a metal are mixed in a thermoplastic or thermosetting adhesive. This anisotropic conductive adhesive is temporarily bonded to the connection terminal surface of the liquid crystal driving device, and the external terminals of the flexible substrate are aligned with the connection terminals of the liquid crystal driving device, and then thermocompression-bonded. Each external terminal of the flexible substrate and each connection terminal of the liquid crystal driving device are mechanically and electrically connected by the adhesive.

[0004] The flexible substrate has a color peculiar to the polyimide resin, and it is difficult to see the external terminals from the film surface (the surface opposite to the wiring pattern). Here, an alignment hole for exposing external terminals to the other surface of the substrate is provided in the external connection terminal portion of the flexible substrate described in Japanese Unexamined Patent Application Publication No. Hei. However, a structure is conceivable in which the external terminals and the connection terminals of the liquid crystal driving device can be seen through the alignment holes.

However, in the case of a structure in which an alignment hole for exposing the external terminal to the other surface of the substrate is provided in the external connection terminal portion of the flexible substrate, the flexible substrate and the connection terminal of the liquid crystal driving device are connected to each other with an anisotropic conductive adhesive. When connecting using an anisotropic conductive adhesive, there is a difference between the heating temperature and pressure during thermocompression bonding at the external terminal where the hole for alignment is made. There was a problem that the state was likely to be incomplete.

Therefore, when aligning each external terminal of the flexible substrate with each connection terminal of the liquid crystal driving device,
It is described in Japanese Utility Model Publication No. Hei 2-92963,
By providing an alignment hole in the external connection terminal portion of the flexible substrate so that the external terminal is exposed to the other surface of the substrate, the external terminal and the connection terminal of the liquid crystal driving device can be seen through the alignment hole even from the film surface side of the flexible substrate. Without using such a structure, alignment is performed by a method in which a connection terminal formed of an ITO (Indium Tin Oxide) film and an external terminal of a flexible substrate are transmitted through and matched from the glass surface side of the connection terminal of the liquid crystal driving device. I was

[0007]

In order to fix the positions of the flexible substrate and the liquid crystal driving device after the alignment, thermocompression bonding or temporary fixing (temporary compression) is immediately performed while maintaining the positional relationship between the two after alignment. There is a need. However, in the case of the above-mentioned conventional alignment method, thermocompression bonding or temporary fixing is performed from the film surface side of the flexible substrate using a pressing (heating) tool or the like. However, when alignment is performed from the glass surface side of the connection terminal of the liquid crystal driving device, Since the surface to be thermocompression-bonded or temporarily fixed is different from the surface to be viewed at the time of alignment, the structure of a device or jig for performing thermocompression or temporary fixing from alignment becomes complicated and workability is poor.

Therefore, the present invention provides an external connection terminal portion of a flexible substrate provided with an alignment hole through which the external terminal is exposed on the other surface of the substrate. When connecting the flexible substrate and the connection terminal of the liquid crystal drive device using an anisotropic conductive adhesive, the connection using the anisotropic conductive adhesive When the alignment is performed from the glass side of the connection terminals of the liquid crystal driving device, the surface to be seen during alignment is different from the surface to be thermocompression-bonded or temporarily fixed. Flexible board that solves the problem that the structure of the device or jig for crimping or temporary fixing becomes complicated and the workability is poor. An object of the present invention is to provide.

[0009]

In order to solve the above-mentioned problems, a flexible board according to the present invention is provided with an external terminal for connecting a wiring pattern to the outside, and an electric connection between an external terminal and an external connection terminal. A terminal dedicated to alignment irrelevant to connection is provided, and an alignment hole for exposing the alignment terminal is provided on the other surface of the substrate in the alignment terminal portion.

According to this structure, the external connection terminals of the flexible substrate are provided with alignment holes for exposing the external terminals to the other surface of the substrate, so that the external terminals can be passed through the alignment holes even from the film surface side of the flexible substrate. When connecting the flexible substrate and the connection terminal of the liquid crystal drive device using an anisotropic conductive adhesive, the connection using the anisotropic conductive adhesive When the alignment is performed from the glass side of the connection terminals of the liquid crystal driving device, the surface to be seen during alignment is different from the surface to be thermocompression-bonded or temporarily fixed. The effect of eliminating the problem that the structure of the device or jig for crimping or temporary fixing becomes complicated and the workability is poor is obtained. That.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Here, a case where the present invention is applied to a flexible substrate used in a liquid crystal driving device such as a mobile phone will be described.

FIG. 1 is a plan view when the flexible substrate according to the first aspect of the present invention is connected to a connection terminal of a liquid crystal driving device, and FIG. 2 is a sectional view. To explain the configuration,
The flexible substrate 1 has wiring patterns 3 and 4 made of metal foil such as copper formed on one surface (the lower surface in FIG. 1) of a base material film 2 of a polymer material such as a polyimide resin. An opening 5 is provided in the center of the base film 2, and an LSI chip 7 for driving a liquid crystal driving device 6 is provided in the opening 5 at the inner leads 3 a, 4 a connected to the wiring patterns 3, 4 and the LSI chip 7. ILB bump electrode (not shown)
(Inner Lead Bonding) The connection part and the LSI active surface (the lower surface in FIG. 1) are covered with an epoxy resin. In general, a structure in which an LSI chip is connected to a flexible substrate 1 is TAB (Tape Aut).
omated Bonding). The external liquid crystal driving device 6 has a connection terminal 6b formed of ITO, and an external terminal 3 for connecting the connection terminal 6b to the flexible substrate 1.
b is an extension of the wiring pattern 3, and these are arranged in parallel near the outer shape of the flexible substrate 1. Alignment-only terminals 3c that are not connected to the wiring pattern 3 are formed at both ends where the external terminals 3b are arranged, and alignment holes 8 are provided in the alignment-only terminals 3c.
A dedicated alignment terminal 6c that is aligned with the alignment terminal 3c of the flexible substrate 3 is also formed at the connection terminal 6b of the liquid crystal driving device 6. An external terminal 4b is connected to an external component for inputting a power supply and a control signal for operating the LSI, and is generally soldered to an external rigid board or the like.

As shown in FIG. 1, the flexible substrate 1 and the liquid crystal driving device 6 are connected to the external terminals 3b and the connection terminals 6 respectively.
b are arranged to face each other. An anisotropic conductive adhesive 9 is temporarily bonded in advance to the surface 6a of the liquid crystal driving device 6 on which the connection terminals 6b are formed. Here, each external terminal 3
b and each connection terminal 6b are aligned by adjusting the positions of the alignment-dedicated terminals 3c and 6c. In this case, the alignment-dedicated terminal 3c and the corresponding 6c can be seen from the base film 2 surface side (the upper surface in the drawing) through the alignment hole 8 of the base film 2 provided in the alignment-dedicated terminal 3b. While looking at both, adjust the position so that they overlap.

After the alignment is completed as described above, thermocompression bonding or temporary fixing (temporary compression) is performed from the surface of the base film 2 and then thermocompression bonding is performed, whereby each external terminal 3b of the flexible substrate 1 is connected to each liquid crystal driving device 6. The terminals 6b are mechanically and electrically connected by the anisotropic conductive adhesive 9 in a state where they are properly aligned.

As described above, the alignment holes 8 of the base film 2 provided in the alignment-dedicated terminals 3b are provided.
The terminal 3c for alignment only and the corresponding 6c can be seen from the side of the base film 2 (the upper surface in the figure) through the substrate film, so that the connection between the external terminal 3b and the connection terminal 6b by the anisotropic conductive adhesive is incomplete. And the surface to be thermocompression-bonded or temporarily fixed during alignment can be the same, so that the structure of the device or jig that performs thermocompression bonding or temporary fixing from alignment is not complicated, The effect of improving the performance is obtained.

In the case where the flexible substrate 1 of the above embodiment is connected to the liquid crystal driving device 6, the problem that the base film 2 of the flexible substrate 1 expands during thermocompression and the position before thermocompression is shifted. By forming the alignment-dedicated terminal 3c and the corresponding 6c in a size in consideration of the displacement due to expansion in advance, it is easy and accurate without considering the displacement of the external terminal 3b and the connection terminal 6b before crimping. High positioning accuracy after crimping is obtained.

[0017]

As described above, according to the present invention, in a flexible substrate having a wiring pattern made of metal foil formed on one surface of a substrate, there is no relation to the electrical connection between external terminals and external connection terminals. By providing a dedicated terminal for alignment, and providing an alignment hole to expose the alignment terminal on the other surface of the substrate in the alignment terminal portion, the alignment terminal can be seen from the other surface of the substrate, Since the surface to be viewed during alignment can be the same as the surface to be thermocompression-bonded or temporarily fixed, the effect of improving the workability without complicating the structure of the device or jig that performs thermocompression bonding or temporary fixing from alignment. There is.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention in which external terminals of a flexible substrate and connection terminals of a liquid crystal driving device are connected by an anisotropic conductive adhesive.

FIG. 2 is a cross-sectional side view taken along a line AA ′ in FIG. 1, showing an embodiment of the present invention, in which external terminals of a flexible substrate and connection terminals of a liquid crystal driving device are connected by an anisotropic conductive adhesive. It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Flexible board 2 ... Base film 3 ... Wiring pattern 3a ... Inner lead 3b ... External terminal 3c ... Alignment dedicated terminal 4 ... Wiring pattern 4a ... Inner lead 5 Opening 6 Liquid crystal driving device 6a Surface on which connection terminals are formed 6b Connection terminal 6c Alignment dedicated terminal 7 LSI 8 Alignment hole 9 ..Anisotropic conductive adhesive

Claims (1)

[Claims] In a flexible board having a wiring pattern made of a metal foil formed on one surface of a substrate, an external terminal portion for connecting the wiring pattern to the outside is electrically connected to an external terminal and an external connection terminal. A flexible terminal provided with an alignment-specific terminal irrelevant to the above, and an alignment hole for exposing the alignment terminal on the other surface of the substrate in the alignment terminal portion.