JPH09293414A - Anisotropic conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive film suited for wide use with high connection reliability by suppressing a conductive particle of contributing no conduction between wiring patterns, to a minimum limit and, ensuring insulation between electrodes adjacent to each other of the same wiring pattern. SOLUTION: This conductive film, like an ITO electrode formed in a liquid crystal panel substrate and a TAB electrode in a drive external circuit, connecting two wiring patterns respectively supported to the substrate, is used in electrical connection of these two wiring patterns. The film comprises an insulating resin binder 1 and a conductive substance 2, so as to make density different by a thickness direction of a layer in the conductive substance 2 dispersed in the insulating resin binder 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive film used for connecting a transparent electrode terminal formed on a panel substrate of a liquid crystal display device and a wiring terminal of a driving external circuit.

[0002]

2. Description of the Related Art Conventionally, an anisotropic conductive film has been used to connect a transparent electrode terminal of a liquid crystal display element to a wiring terminal of a driving external circuit. As shown in FIG. 3, the structure of the anisotropic conductive film is such that metal particles of solder, nickel, or the like, or conductive particles 11 obtained by plating the surface of the resin particles with nickel or the like in an insulating resin binder 10 at a constant concentration. The film is formed into a sheet by dispersing with. This anisotropic conductive film, as shown in FIG.
Between the two terminals 13 and 12, the panel substrate that supports the transparent electrode terminal 13 and the driving external circuit substrate that supports the wiring terminal 12 are heated and pressed to narrow the gap in the pressing direction. The metal particles contacting 12 and 13 are conducted only between the terminals, and the insulating resin binder 10 is melted so that the anisotropic conduction between the terminals is fixed to perform the joining.

[0003]

The particles of the conductive material dispersed in the anisotropic conductive film are partially sandwiched between two electrodes facing each other to provide conduction between the two wiring patterns. Most of the other part is filled in the space between the non-electrode parts and does not contribute to conduction between the wiring patterns. They may hinder the insulation between adjacent electrodes of the same wiring pattern.

The present invention has been made in view of the above circumstances, and minimizes a conductive material that does not contribute to conduction between wiring patterns, ensures insulation between adjacent electrodes of the same wiring pattern, and achieves a wide area. It is intended to provide an anisotropic conductive film having high connection reliability and suitable for use.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies aimed at achieving the above object, the present inventors have found that the distribution of the conductive material in the insulating resin binder is unevenly distributed in the effective layer portion. The present invention has been completed by finding out that the above object is achieved.

That is, the present invention relates to an anisotropic conductive film which is used for electrically connecting two wiring patterns supported by a substrate and electrically connecting the two wiring patterns. Is an anisotropic conductive film characterized in that the conductive material dispersed in an insulating resin binder has a different density in the thickness direction of the layer, and is formed on the panel substrate of the liquid crystal display element. In the anisotropic conductive film used for electrical connection between the transparent electrode terminal and the wiring terminal of the driving external circuit, the density of the conductive material near the surface facing the liquid crystal side at the time of bonding is The anisotropic conductive film according to claim 1, which is higher in density, and also the anisotropic conductive film according to claim 1 or 2, wherein the conductive material is a conductive material containing a ferromagnetic material.

Hereinafter, the present invention will be described in detail.

The insulating resin of the present invention is not particularly limited as long as it can be dissolved in a solvent to adjust the solid content and can form a coating film, and can be used in the present invention. Specific resins include, for example, acrylic rubber, acrylonitrile butadiene rubber, polystyrene, polymethylmethacrylate, polyurethane, polyvinyl chloride, polybutadiene,
Nylon or copolymers of these, polycarbonate,
Examples thereof include caprolactone-based polyester, ether-based polyester, adipate-based polyester, and epoxy resin. Insulation resin pressure bonding is performed by heat welding,
Various mechanisms such as thermosetting pressure bonding and photo-curing pressure bonding can be used.

The conductive substance used in the present invention may be any conductive substance such as granular metal particles, granular resin, particles having a metal layer on the surface of inorganic or organic particles,
There is no particular limitation. Examples of these conductive materials include particles of copper, silver, nickel, etc., particles having a resin, inorganic or organic surface having copper, silver, nickel layers, etc., and these particles may be used alone or in combination of two or more. Can be used. The particle size of the conductive material is preferably selected according to the height of the connecting electrodes of the two conductive patterns,
For example, the thickness is preferably 1 to 18 μm, and if it is out of this range, good connection cannot be obtained, which is not preferable. The conductive material can contain a ferromagnetic material or a ferromagnetic material that can become a magnetic material in a strong magnetic field. This ferromagnetic substance is effective because it can control the density state of the conductive material.

It is desirable that the conductive material is contained in an amount of 2% by weight or more based on the insulating resin. If it is less than 2% by weight, good connection cannot be obtained, which is not preferable.

The method of forming a layer in which a conductive material is dispersed in an insulating resin is not particularly limited, but usually, the insulating resin is dissolved in a solvent to adjust the solid content to obtain a desired particle size. A predetermined amount of the conductive material is mixed to form a coating film having a constant thickness. Therefore, it is possible to form a coating film having a constant thickness in which a desired amount of a conductive material having a desired particle size is mixed according to required characteristics and the like.

According to the structure of the present invention, the particles of the conductive material in the layer in which the particles of the conductive material are dispersed in the insulating resin are sandwiched between the electrodes of the two wiring patterns facing each other by the applied pressure to ensure the conduction. However, the density of conductive material particles is increased on the electrode side having a low height, for example, on the transparent electrode terminal side formed on the liquid crystal panel substrate, and the conductive material particle is on the electrode side having a high height, for example, the wiring terminal side of the driving external circuit. By reducing the density of the electrodes, it is possible to enhance the efficiency of the conductive material used for bonding between the electrodes facing each other, and at the same time, it is possible to secure the insulation between the electrodes of the same wiring pattern adjacent to each other. If the heights of both electrodes are substantially equal to each other, it is desirable to form a layer in which the density of the conductive material is increased in the center of the conductive film in the thickness direction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

EXAMPLE Nickel particles (particle size: 10 μm, 3.5% by weight) were mixed with the coating material obtained by dissolving an insulating resin in toluene to adjust the solid content, and coated on a polyester substrate by a gravure method, and then the substrate was coated. From the side, it was dried while applying a magnetic field with a permanent magnet to obtain a coating film having a thickness of 30 μm. The state of this coating film is shown in FIG. The conductive resin 2 is dispersed in the insulating resin binder 1 in the thickness direction so as to have different densities.

In the coating film thus obtained, the side with the higher density of the conductive material was pasted on the ITO electrode (pitch 0.2 mm) on the glass substrate, and the side with the lower density of the conductive material was overlaid with TAB. Between these terminals at 180 ° C, 15kg /
Anisotropic conductive film was prepared by press-bonding with cm ² for 20 seconds. This state is shown in FIG. The particles of the conductive material 2 are slightly dispersed on the TAB electrode 3 side, and
The insulation of the electrode 3 is secured. In addition, the conductive material 2 is
It is sandwiched between the TAB electrode 3 and the ITO electrode 4 to ensure necessary conduction.

Comparative Example A paint obtained by dissolving an insulating resin in toluene to adjust the solid content was added with nickel particles (particle size: 10 μm, 3.5% by weight).
Was mixed and applied on a polyester substrate by a gravure method and then dried to obtain a coating film having a thickness of 30 μm. As shown in FIG. 3, the conductive material 11 dispersed in the insulating resin binder 10 is used.
Was almost uniform in the thickness direction.

The coating film thus obtained was applied to I on a glass substrate.
Stick it on the TO electrode (pitch 0.2 mm), stack the TAB on it, and then connect it between these terminals at 180 ° C and 15 kg / cm ² for 20 minutes.
Anisotropic conductive films were formed by pressing and bonding for seconds. This state is shown in FIG. The conductive material 11 is the TAB electrode 1
The TAB electrode 1 which is sandwiched between the ITO electrode 13 and the ITO electrode 13 and has the necessary conductivity, but in which the particles of the conductive material 11 are adjacent to each other.
It may be unnecessarily present between the two TAB electrodes, and it may be difficult to ensure the insulating properties of the adjacent TAB electrodes 12.

The resistance between the opposing wiring patterns of the anisotropic conductive film and the resistance between the adjacent electrodes of the same wiring pattern in the thus-prepared Examples and Comparative Examples were measured, and the results are shown in Table 1.

[0019]

[Table 1]

[0020]

As is apparent from the above description and Table 1, the anisotropic conductive film of the present invention minimizes the conductive material that does not contribute to the bonding and prevents the insulation between the adjacent electrodes of the same wiring pattern. In addition, since the ratio of the particles that contribute to the bonding between the counter electrodes of the conductive material contained therein can be increased, the content ratio of the conductive material in the entire coating film can be reduced, and the cost can be reduced. Is.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an anisotropic conductive film of the present invention.

FIG. 2 is a schematic cross-sectional view showing a bonded state of the anisotropic conductive film of the present invention.

FIG. 3 is a schematic sectional view of a conventional anisotropic conductive film.

FIG. 4 is a schematic cross-sectional view showing a joined state of a conventional anisotropic conductive film.

[Explanation of symbols]

 1,10 Insulating resin binder 2,11 Conductive material 3,12 TAB electrode 4,13 ITO electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01R 11/01 H01R 11/01 A

Claims (3)

[Claims] 1. An anisotropic conductive film, which is used for electrically connecting two wiring patterns supported by a substrate and electrically connecting the two wiring patterns, comprising an insulating resin binder and a conductive material. An anisotropic conductive film comprising a conductive substance dispersed in an insulating resin binder and having different densities in the layer thickness direction. 2. An anisotropic conductive film used for electrical connection between a transparent electrode terminal formed on a panel substrate of a liquid crystal display element and a wiring terminal of a driving external circuit, near a surface facing the liquid crystal side at the time of bonding. The anisotropic conductive film according to claim 1, wherein the density of the conductive material is higher than the density of the conductive material near the back surface. 3. The anisotropic conductive film according to claim 1, wherein the conductive substance is a conductive substance containing a ferromagnetic material.