JPH09259635A - Anisotropic conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive film which can be repaired easily within a short time by an organic solvent. SOLUTION: This anisotropic conductive film, which is produced by pressure- curing a sheet-like material produced by dispersing conductive particles in a curable insulating binder and which carriers out selective electrical continuity based on the steps of a conductor pattern used for the pressure-curing, has a multilayer structure consisting of at least two layers, and at least one layer of the multilayers contains a solvent-soluble component which does not practically take part in the curing reaction. A solvent-soluble component-containing layer which contains the largest amount of the solvent-soluble component is formed as a layer to be brought into contact with a liquid crystal panel.

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. The structure of the anisotropic conductive film is such that a curable insulating resin binder is used to disperse metal particles such as solder or nickel, or conductive particles obtained by plating the surface of resin particles with nickel at a predetermined concentration to form a sheet. It was formed into a film. This anisotropic conductive film is arranged between the two terminals of the liquid crystal display element, and heats and presses the panel substrate supporting the transparent electrode terminals and the driving external circuit substrate supporting the wiring terminals, whereby The metal particles that are in contact with each other with a narrow space are conducted only between the two terminals, and the insulating resin binder undergoes a curing reaction so that the anisotropic conduction between the terminals is fixed to perform the joining.

In many cases, an epoxy thermosetting resin is used as the insulating resin binder in order to obtain reliability. More specifically, the epoxy resin and, as its curing agent, a polyamide resin, amines, imidazoles are used. , Melamines, acid anhydrides, etc. are used.

[0004]

When the transparent electrode terminal of the liquid crystal panel and the wiring terminal of the driving external circuit are bonded by using the anisotropic conductive film, a defect such as a positional deviation between the transparent electrode terminal and the wiring terminal is caused. May occur. In such a case, in order to reproduce a liquid crystal display element having a high added value, it is necessary to repair the adhesive layer, which removes the anisotropic conductive film adhesive-cured to the transparent electrode terminal with a general-purpose solvent. When an epoxy thermosetting resin is used as the resin binder, there is a drawback that it is very difficult to carry out repair in a short time after curing and the yield is deteriorated.

The present invention has been made to solve the above-mentioned drawbacks, and an object thereof is to provide an anisotropic conductive film which can be easily repaired with an organic solvent in a short time.

[0006]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that a layer composed of an epoxy resin and a thermoplastic resin soluble in an organic solvent after curing. , A multilayer structure in which a solvent-soluble component-containing layer such as rubber is separated, and by bonding the soluble component-containing layer to the transparent electrode terminal side of the liquid crystal panel to be reproduced,
The present invention has been completed by finding out that the above object is achieved.

That is, the present invention is an anisotropic method in which conductive particles are dispersed in an insulative binder that undergoes a curing reaction to form a sheet, which is pressure-bonded and cured, and a conductive pattern used for pressure bonding causes selective conduction. The anisotropic conductive film has a multilayer structure of two or more layers, and at least one layer of the multilayer contains a solvent-soluble component that does not substantially participate in the curing reaction. Then, it is an anisotropic conductive film for a liquid crystal panel, in which the solvent-soluble component-containing layer containing the most solvent-soluble component is formed as a layer in contact with the liquid crystal panel.

Hereinafter, the present invention will be described in detail.

As the epoxy resin preferably used as the insulating binder of the present invention, a generally used epoxy resin can be used as long as it is a polyvalent epoxy resin having two or more epoxy groups in one molecule. is there. Specific examples include novolac resins such as phenol novolac and cresol novolac, polyhydric phenols such as bisphenol A, bisphenol F, resorcin, bishydroxydiphenyl ether, ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, Glycidyl obtained by reacting polyhydric alcohols such as polypropylene glycol, ethylenediamine, triethylenetetramine, polyamino compounds such as aniline, polyvalent carboxy compounds such as adipic acid, phthalic acid and isophthalic acid with epichlorohydrin or 2-methylepichlorohydrin Type epoxy resin, dicyclopentadiene epoxide, aliphatic and alicyclic epoxy resin such as butadiene dimer epoxide, and the like, Curing reactive binder corresponding to these epoxy resins may be used alone or in combination.

The curing component of the epoxy resin used in the present invention can be used without particular limitation as long as it has two or more active hydrogens in one molecule.
Specifically, for example, diethylene triamine,
Polyamino compounds such as triethylenetetramine, metaphenylenediamine, dicyandiamide, polyamidoamine, phthalic anhydride, methylnadic acid anhydride, hexahydrodide phthalic anhydride, organic acid anhydrides such as pyromellitic dianhydride, phenol novolac, cresol novolac, etc. Novolak resins and the like can be used, and these can be used alone or in combination of two or more kinds.

As the solvent-soluble component used in the present invention,
Any thermoplastic resin or rubber that does not substantially participate in the curing reaction and has good compatibility with the epoxy resin component and is soluble in a solvent can be widely used. Specific thermoplastic resins include, for example, polystyrene, polymethylmethacrylate, polyurethane, polyvinyl chloride, polybutadiene, nylon or copolymers thereof, polycarbonate, caprolactone-based polyester, ether-based polyol, adipate-based polyester and the like. Specific examples of the rubber include acrylic rubber and acrylonitrile butadiene rubber, which may be used alone or in combination of two or more.

The conductive particles used in the conductive film of the present invention are not particularly limited as long as they are metal particles or inorganic or organic particles having a metal layer. Specific examples of the metal particles include particles of copper, silver, nickel and the like, and a metal layer provided on the inorganic or organic particles includes a layer of copper, silver, nickel and the like, and these particles may be used alone or in combination of two or more kinds. Can be used.

An anisotropic conductive film is prepared by using each of the above components. For example, first, an epoxy resin is dissolved in toluene to form a paint, and a predetermined amount of conductive particles having a predetermined particle size are mixed to form a film, which is used as a first film. Next, a curing agent, a curing accelerator, and a thermoplastic resin are dissolved in toluene and added to form a coating material, and a predetermined amount of conductive particles having a predetermined particle diameter are mixed to form a film, thereby forming a second film. The second film is overlaid on the first film to form an anisotropic conductive film.

To use the anisotropic conductive film, the above-mentioned anisotropic conductive film is superposed on the ITO electrode terminal on the glass substrate prepared separately, TAB is superposed, and the terminals are heated and pressure-bonded to each other. Let it harden.

The anisotropic conductive film of the present invention is constituted as described above, so that the reactive composition separated into multiple layers is melted and mixed by the heat and pressure applied at the time of electrode bonding, and the curing reaction. To start. As a result, the conductive particles sandwiched between the two opposing terminals are fixed, and anisotropic conduction is secured. On the other hand, the components of each layer are not completely mixed, and the weight of the solvent-soluble thermoplastic resin component of the outermost layer becomes large near the interface of the ITO electrode even after curing, and the repair can be easily performed.

In the multilayer structure, the ease of repair can be adjusted by using two or more layers containing solvent-soluble components having different contents.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, examples of the present invention will be described, but the present invention is not limited to these examples.

EXAMPLE An epoxy resin was dissolved in toluene to adjust the solid content, and the resulting coating material was mixed with conductive particles (particle size: 5 to 10 μm, 3.5% by weight) to obtain a film A having a thickness of 15 μm. Furthermore, conductive particles (particle size 5 to 10 μm, 3.5% by weight) are added to the coating material obtained by dissolving the epoxy resin curing agent and accelerator, and the acrylic rubber for obtaining solvent solubility in toluene to adjust the solid content. By mixing, a film B having a thickness of 15 μm was obtained. The film B was laminated on the film A to form a two-layer film C having a thickness of 30 μm.

Immediately after the production of this film C, the above film C was laminated on an ITO electrode (pitch 0.2 mm) on a glass substrate prepared separately so that the rubber component was on the ITO electrode side, and TAB was further laminated. 15kg / between these terminals
Anisotropic conductive film was prepared by pressure-bonding for 20 seconds at 20 cm 2 and heat-bonding.

COMPARATIVE EXAMPLE 1 An epoxy resin, a curing agent, an accelerator and a rubber for obtaining a film property were dissolved in toluene to adjust the solid content, and the conductive particles (particle size 5 to 10 μm, 3.5 weight) were added to the obtained coating material. %) Was mixed to form a film D having a thickness of 30 μm.

Immediately after the production of this film D, the above film D was superposed on an ITO electrode (pitch 0.2 mm) on a glass substrate, which was prepared separately, and TAB was superposed on this film, and the space between these terminals was applied at 15 kg / cm 2 for 20 seconds. Anisotropic conductive films were prepared by pressure bonding and heat bonding.

Comparative Example 2 All of the components used in Example 1 were dissolved in toluene to adjust the solid content, and the resulting coating material was coated with conductive particles (particle size 5-10 μm).
m, 3.5 wt%) to obtain a film E having a thickness of 30 μm.

Immediately after the production of this film E, the above film E was superposed on an ITO electrode (pitch 0.2 mm) on a glass substrate, which was prepared separately, and TAB was superposed thereon, and the space between these terminals was applied at 15 kg / cm 2 for 20 seconds. Anisotropic conductive films were prepared by pressure bonding and heat bonding.

The number of repairs of the anisotropic conductive film thus obtained was measured, and the results are shown in Table 1.

[0025]

[Table 1] * 1: TAB of the anisotropic conductive film was peeled off, the anisotropic conductive film adhered on the ITO electrode was rubbed with acetone, and the number of times until complete peeling was measured.

[0026]

As is apparent from the above description and Table 1, the anisotropic conductive film of the present invention can be repaired for a short time after curing.

Claims (2)

[Claims] 1. An anisotropic conductive film in which conductive particles are dispersed in an insulative binder that undergoes a curing reaction, and a sheet-shaped product is pressure-bonded and cured, and selective conduction is achieved by a step of a conductor pattern used for pressure-bonding. An anisotropic conductive film having a multilayer structure of two or more layers, at least one layer of which contains a solvent-soluble component that does not substantially participate in the curing reaction. 2. An anisotropic conductive film for a liquid crystal panel used for connection with an external wiring terminal, wherein a solvent-soluble component-containing layer containing the most solvent-soluble component is formed as a layer in contact with the liquid crystal panel. The anisotropic conductive film according to claim 1, wherein