KR19980066135A - Manufacturing method of anisotropic conductive film - Google Patents

Abstract

1. Fields to which the invention described in the claims belong

The present invention relates to a method for producing an anisotropic conductive film used for the electrical connection of a fine circuit board.

2. The technical problem to be solved by the invention

Provided is a method for producing an anisotropic conductive film that can shorten the film production time and reduce the contact resistance of the film by uniformly dispersing the conductive particles in the coating solution for the film within a short time.

3. Summary of the solution of the invention

The conductive particles and the coupling agent are first mixed in the presence of an organic solvent to prepare a mixture, and then the mixture is added to a solution composed of a polymer resin for a connecting adhesive, a curing agent, and a solvent to prepare a coating solution for a film.

4. Important uses of the invention

The anisotropic conductive film produced by the method of the present invention is used for connecting a liquid crystal display and a flexible circuit board.

Description

The manufacturing method of an anisotropic conductive film.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an anisotropic conductive film used for the electrical connection of fine circuit boards, in particular the connection of liquid crystal displays (LCDs) and flexible circuit boards (FPCs), and the micro connection of semiconductor chips and chip-mounted circuit boards.

In general, an anisotropic conductive film is prepared by coating a resin composition composed of an adhesive polymer resin, conductive particles, a curing agent, a coupling agent, and a solvent on a release film.

In the prior art for producing such an anisotropic conductive film, at least one resin selected from a thermoplastic resin, a thermosetting resin, or a photocurable resin is mixed and used as a polymer resin for an adhesive.

Specific examples of the thermoplastic resin, the thermosetting resin, or the photocurable resin include styrene-butadiene resin, styrene resin, ethylene-vinyl resin, acrylonitrile butadiene rubber, silicone resin, acrylic resin, epoxy resin, urethane resin, phenol resin, and amide resin. Or acrylate resins.

If necessary, a tackifier, a crosslinking agent, an anti-aging agent, a coupling agent, and the like, which are represented by rosin, a turbine resin, and a gumarodine resin, may also be used as the polymer resin for the adhesive.

As a curing agent, one obtained by microencapsulating a reaction product of an amidazole with an epoxy compound with a thermoplastic resin may be used.

As the conductive particles, metal particles may be used, or particles in which metal is impregnated in the polymer beads may be used.

On the other hand, in order to evenly distribute the conductive particles, organic sulfur compounds having excellent affinity with organic substances and inorganic metals may be used as coupling agents to improve the dispersion speed and dispersion state of the conductive particles.

As the solvent used for preparing the polymer resin composition for an adhesive, acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, xylene, methyl alcohol, isopropyl alcohol, and / or n-butyl alcohol may be used alone or in combination. Mix and use. These solvents have high polarity to improve the mixing stability of the resin solution after blending.

As a conventional technique for preparing a coating liquid for a film using the above-described adhesive polymer resin, conductive particles, curing agent, coupling agent, and solvent, the adhesive polymer resin is dissolved in a solvent to prepare an adhesive solution, and then a curing agent and After the coupling agent is added, the conductive particles are subsequently added and dispersed to prepare a coating solution for a film.

That is, the coupling agent is added before the conductive particles in preparing the coating liquid for the film, and then the conductive particles are added and dispersed.

When the coating liquid for the film is prepared in this way, uniform dispersion of the conductive particles is difficult, a long time is required for the dispersion of the conductive particles, and a high contact resistance of the manufactured film occurs.

The present invention provides a method for producing an anisotropic conductive film that can shorten the film production time and reduce the contact resistance of the film by uniformly dispersing the conductive particles in the coating liquid for a short time.

1 is a cross-sectional view of the anisotropic conductive film of the present invention.

2 is a cross-sectional view of a state before connecting a liquid crystal display substrate and a driving integrated circuit using an anisotropic conductive film.

In Fig. 1, 1 is an adhesive, 2 is a metal coating layer, 3 is conductive polymer particles, and 4 is a release film. In Fig. 2, 5 is an adhesive, 6 is conductive particles, 7 is a liquid crystal display substrate, 8 is a driving integrated circuit, 9 is an electrode of the liquid crystal display substrate, and 10 is a tab electrode.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an anisotropic conductive film used for the electrical connection of fine circuit boards, in particular the connection of liquid crystal displays (LCDs) and flexible circuit boards (FPCs), and the micro connection of semiconductor chips and chip-mounted circuit boards.

More specifically, in order to uniformly disperse the conductive particles in the coating solution for the film in a short time, the conductive particles and the coupling agent are first mixed in the presence of an organic solvent to prepare a mixture, and then the mixture is mixed with a polymer resin, a solvent and The present invention relates to a method of manufacturing an anisotropic conductive film by adding a solution for a film to prepare a coating solution for a film and coating the film on a release film.

That is, the present invention relates to a method of first mixing conductive particles and a coupling agent in an organic solvent, and then adding and dispersing these mixtures in an adhesive solution.

The polymer resin for adhesives used in the present invention is at least one resin selected from thermoplastic resins, thermosetting resins and photocurable resins.

Specific examples of the thermoplastic resin, the thermosetting resin, or the photocurable resin include styrene-butadiene resin, styrene resin, ethylene-vinyl resin, acrylonitrile butadiene rubber, silicone resin, acrylic resin, epoxy resin, urethane resin, phenol resin, and amide resin. Or acrylate resins. If necessary, a tackifier, a crosslinking agent, an anti-aging agent and a coupling agent such as rosin, a turbine resin, or a gumarodine resin may also be used.

The curing agent may be a microencapsulated product of the reaction of the imidazole and the epoxy compound. The imidazole compound used herein is imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-cyanoethyl-2 -Methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and the like are used. Moreover, glycidyl ether type epoxy compounds, such as bisphenol A type, a phenol noblock, a bisphenol F type, or a block bisphenol A type, can be used as an epoxy compound which reacts with the above-mentioned imidazole compound, and produces | generates an imidazole derivative epoxy compound. In addition, a polymer such as polystyrene, gelatin or polyisocyanate may be used as the thermoplastic resin encapsulating the imidazole derivative epoxy compound produced above. On the other hand, in order to evenly distribute the conductive particles, the organic sulfur compounds and organic sulfur compounds with excellent extinguishing properties can be used as a coupling agent to improve the dispersion rate and dispersion state of the conductive particles.

As the solvent used for preparing the adhesive solution, acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, xylene, methyl alcohol, ethyl alcohol, isopropyl alcohol and / or n-butyl alcohol may be used alone or in combination. Mix and use the above. These solvents have high polarity to improve the mixing stability of the resin solution after blending.

In the present invention, in preparing the coating liquid for film, the mixture (A) is prepared by first mixing the conductive particles and the coupling agent in the presence of an organic solvent.

Organic solvents used here include toluene, benzene, xylene, carbon tetrachloride, chloroform, dichloromethane and dichloroethane. These organic solvents do not mix with water.

On the other hand, the polymer resin for connectivity adhesives mentioned above is dissolved in a solvent, the adhesive solution (B) is manufactured, and a hardening | curing agent is added here.

To the adhesive solution (B) to which the curing agent was added, a mixture (A) in which the conductive particles and the coupling agent were mixed in the presence of an organic solvent was added to prepare a coating solution for a film, and coated on these release films with a thickness of 20 to 50 μm. And drying to prepare a release conductive film.

When the release conductive film is manufactured by the method of the present invention as described above, the conductive particles and the coupling agent are added simultaneously, so that the conductive particles in the adhesive solution are uniformly dispersed in a short time, and the connection resistance of the film is also reduced.

1 shows a cross-sectional view of the anisotropic conductive film of the present invention.

The method of connecting the liquid crystal display substrate and the driving integrated circuit thereof using the anisotropic conductive film of the present invention thus produced will be described in detail with reference to FIG. 2.

2 is a cross-sectional view of a state before connecting a liquid crystal display substrate and its driving circuit using an anisotropic conductive film.

The anisotropic conductive film is sandwiched between the electrode 9 of the liquid crystal display substrate 7 and the tab electrode 10 of the driving integrated circuit 8, and then the anisotropic conductive film is heated to a constant temperature. Subsequently, by pressing the liquid crystal display substrate 7 downward, the adhesive 6 is filled in the space between the liquid crystal display substrate 7 and the driving integrated circuit 8, and the conductive particles 5 are formed on the electrodes of the liquid crystal display substrate ( 9) and the tab electrode 10 of the driving integrated circuit to provide an electrically conductive path.

More specifically, the anisotropic conductive film is adhered onto the liquid crystal display substrate 7 using the self-taking property of the film itself, and then 5 seconds under a temperature of 80 to 100 ° C. and a pressure of 10 kgF / cm 2. Is pressed and the release film 4 is removed. By using the self-tacking property of the film, the circuit on the liquid crystal display board to which the anisotropic conductive film is press-bonded is aligned to the circuit on the tab or flexible PCB, and then the temperature of 170 to 180 ° C. and 20 kg F The liquid crystal display substrate and its driving integrated circuit are connected by pressing for 20 seconds under a pressure of / cm 2.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to Examples.

Example 1

46 parts by weight of bisphenol A type epoxy resin YD-128 (product of Kukdo Chemical) and 46 parts by weight of phenoxy resin YP-50 (Kukdo Chemical) were reflux-dissolved in a toluene / methylethylketone solvent with a volume ratio of 3: 1. A solution (B) is prepared.

Meanwhile, 1 wt% of conductive particles having a particle size of 5 ± 0.1 μm coated with nickel / gold on a polymer particle (based on resin solid content) and 1 part by weight of KBM-403 (produced by Shin-Echu), a silane coupling agent, were used in a 3 ml toluene organic solvent. Mixing under produces a mixture (A).

After cooling the adhesive solution (B) to room temperature, 4 parts by weight of the curing agent 2MZ (Kukdo Chemical Products) and the mixture (A) were added thereto, followed by homogeneous mixing using a homomix to prepare a coating solution for a film. do.

The film coating solution thus prepared was coated on a release film in a thickness of 25 μm to prepare an anisotropic conductive film. By using the manufactured anisotropic conductive film, thermocompression bonding of a flexible circuit board (FPC) and a transparent conductive circuit glass substrate (ITO circuit) with a line width of 0.1 mm, a pitch of 0.2 mm, a thick film of 35 μm, and 160 terminal circuits is performed. Connected. The result of evaluation of the adhesive force and connection resistance value after connection is shown in Table 1.

[Examples 2 to 5]

An anisotropic conductive film was prepared in the same manner as in Example 1 except that the amount of the conductive particles was changed as shown in Table 1 when the silane coupling agent and the conductive particles were mixed in a toluene solvent to prepare the mixture (A).

The thermally compressed flexible circuit board (FPC) and transparent conductive circuit glass substrate (ITO circuit) having a line width of 0.1 mm, a pitch of 0.2 mm, a thick film of 35 µm, and 160 terminal circuits were manufactured by using the manufactured anisotropic conductive film. Connected. The result of evaluation of the adhesive force and connection resistance value after connection is shown in Table 1.

Comparative Example 1

46 parts by weight of bisphenol A-type epoxy resin YD-128 (product of Kukdo Chemical Co., Ltd.) and 46 parts by weight of phenoxy resin YP-50 (Kukdo Chemical Co., Ltd.) were reflux-dissolved in a 3: 1 volumetric-toluene / methylethylketone solvent. Prepare a solution for the adhesive.

After cooling the adhesive solution to room temperature, 4 parts by weight of 2MZ (product of Kukdo Chemical Co., Ltd.) and 1 part by weight of KBM-403 (product of Shin-Echu), which is a silane coupling agent, were added thereto, and nickel / gold was added to the polymer particles. 4 wt% (based on resin solid content) of conductive particles having a coated particle diameter of 5 ± 0.1 μm was added thereto, and then uniformly mixed using a homomixer to prepare a coating solution for a film. The film coating solution thus prepared was coated on a release film in a thickness of 25 μm to prepare an anisotropic conductive film.

The thermally compressed flexible circuit board (FPC) and transparent conductive circuit glass substrate (ITO circuit) having a line width of 0.1 mm, a pitch of 0.2 mm, a thick film of 35 µm, and 160 terminal circuits were manufactured by using the manufactured anisotropic conductive film. Connected. The result of evaluation of the adhesive force and connection resistance value after connection is shown in Table 1.

Comparative Example 2

An anisotropic conductive film was prepared in the same manner as in Comparative Example 1 except that the amount of the conductive particles was changed to 10% by weight (based on resin solid content).

The thermally compressed flexible circuit board (FPC) and transparent conductive circuit glass substrate (ITO circuit) having a line width of 0.1 mm, a pitch of 0.2 mm, a thick film of 35 µm, and 160 terminal circuits were manufactured by using the manufactured anisotropic conductive film. Connected. The results of evaluating the gluing adhesion and the connection resistance after connection are shown in Table 1.

Adhesion was measured by peel test, and connection resistance was measured by Four Probe Method after initial connection and high temperature and high humidity.

In the anisotropic conductive film prepared by the production method of the present invention, the conductive particles are evenly dispersed in the adhesive component within a short time, thereby shortening the film production time and reducing the connection resistance value of the film.

Claims (4)

In preparing an anisotropic conductive film containing a polymer resin for conductive adhesive, a conductive particle, a curing agent, a coupling agent and a solvent as main components, the conductive particles and the coupling are first mixed in the presence of an organic solvent to prepare a mixture, and then the mixtures are prepared. The manufacturing method of the anisotropic conductive film characterized by adding in the solution which consists of a polymeric resin for connection adhesives, a solvent, and a hardening | curing agent. The method for producing an anisotropic conductive film according to claim 1, wherein the organic solvent used when mixing the conductive particles and the coupling agent is toluene, benzene, xylene, carbon tetrachloride, chloroform, dichloromethane or dichloroethane. The method for producing an anisotropic conductive film according to claim 1, wherein the conductive particle content is 3 to 10% by weight based on the polymer resin for the connecting adhesive. The method for producing an anisotropic conductive film according to claim 1, wherein the conductive particles are particles in which metal is impregnated in the polymer beads.