JPH07192537A - Conductive film and manufacture thereof - Google Patents

Abstract

PURPOSE:To concurrently improve at a low cost conductivity between electrodes to be joined and an insulation property between adjoining electrodes by adding and scattering conductive particles and nonconductive bars into the adhesive of a dielectric film for sticking opposite electrodes to electrically connect them. CONSTITUTION:An ITO transparent electrode 2 mounted on a glass substrate 1 and a copper electrode 5 mounted on a flexible electrode plate 4 are faced to be stuck via a conductive film 3 to be electrically connected. Conductive particles 7 and bars 8 such as glass fibers are added and scattered to the binder 6 of the adhesive of this conductive film 3. The particles are preferable to have deformability such as gold-plated polymer particles. Part of the particles and bars is sandwiched between both the electrodes, and the particles 7 are electrically connected and the bars 8 keep given intervals. It is preferable that the particles 7 and the bars 8 are added and scattered, and then the conductive film 3 is extended in a surface direction and in a direction orthogonal to a direction between adjoining electrodes to separate the particles 7 in a surface direction to orient the bars 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive film used as a connecting material for opposing electrodes, and more particularly to a conductive film used for connecting high density electrodes in which a large number of electrodes are provided in close proximity to each other. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in this type of technique, a conductive film used for connecting transparent electrodes of a liquid crystal panel is well known. This conductive film is an IT that is difficult to solder
It is often used for bonding with oxide-based transparent electrodes such as O (indium oxide / tin oxide). FIG. 6 shows an example of the conductive film. Two substrates 101a on which electrodes 100 are formed,
The conductive film 102 is sandwiched between 101b. The conductive film 102 is a binder 1 mainly made of resin.
03, and conductive particles 104 are contained in the binder 103.
Has been diffused. As the conductive particles 104, metal particles such as gold, nickel and solder are used. recently,
Instead of the metal particles, deformable conductive particles that can provide a large contact area with the electrode 100 are mainly used. Polymer particles plated with gold or nickel are used as the deformable conductive particles. Both substrates 101a, 1
By pressing 01b, the electrode 100 becomes the metal particles 1
04a is contacted and electrically connected, and an insulating state is maintained between adjacent electrodes 100.

In recent years, the density of the electrode 100 has been further increased,
The electrode width and the electrode interval are becoming narrower. Therefore, as shown in FIG. 6, adjacent conductive particles 104, 10
4a may come into contact with each other, or dielectric breakdown may occur due to electrostatic induction, discharge, or the like, resulting in defective insulation, which makes it difficult to maintain insulation in the lateral direction adjacent to the electrodes. In order to solve this problem, a conductive film in which conductive particles are coated with an electrically insulating film has been proposed.

As shown in FIG. 7, the conductive film 106 in which the conductive particles 107 are coated with the insulating film 105 is formed on the substrate 10.
Pressure and heat are applied in the joining direction of the electrodes 100 of 1a and 101b, and the conductive particles 107 are bonded so as to be pressed.
Then, the insulating film 105 at the portion of the conductive particle 107a that is in contact with the electrode 100 is removed, and the electrode 100 becomes the conductive particle 107a.
Conducts with a. Since sufficient force is not applied to the portion where the electrode 100 is not present, the insulating film 105 of the conductive particles 107 is not applied.
You can't get rid of it. Therefore, even if the conductive particles are close to each other, the insulating film 105 maintains the lateral insulation, and
Conduction is obtained in the joining direction.

[0005]

However, in the above prior art, since the conductive particles 107, 107a are coated with the insulating film 105, the resistance in the joining direction which requires conduction increases,
Continuity becomes unstable and reliability decreases. In order to reduce the resistance in the joining direction, heat is applied as described above, and the conductive particles 1
Although 07a is pressed, sometimes the conductive portion is exposed and the lateral insulation may be deteriorated. Therefore, the size and concentration of the conductive particles are limited in order to secure the insulating property in the lateral direction, and it is difficult to improve the conductivity between the opposing electrodes. Also, due to heating, the amount of deformation of the polymer particles plated with the conductive layer cannot be controlled,
The thickness of the conductive adhesive layer (gap between electrodes) cannot be controlled. Therefore, there is a concern that the reliability of the joint may be deteriorated due to the strain generated in the thermal cycle or the like.

Further, in order to obtain the effect of conducting in the joining direction and maintaining the insulation in the lateral direction, it is necessary to strictly control the thickness of the insulating film 105 and the dispersion density of the conductive particles, and the manufacturing cost of the conductive particles 107. However, there is a problem that

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is a low-cost conductive film having high conductivity between electrodes to be joined and high insulation between adjacent electrodes. It is to provide the manufacturing method.

[0008]

In order to achieve the above object, in the first invention, a method for producing a conductive film is provided in which electrodes facing each other with a film sandwiched therebetween are bonded and the electrodes are electrically connected. The gist of the invention is to add and diffuse conductive particles and non-conductive rods to the adhesive of the conductive film.

The gist of the second invention is that after the conductive particles and the non-conductive rod are added and diffused, the conductive film is stretched in the plane direction. The gist of the third invention is that the film is stretched in a direction at a right angle to the direction between adjacent electrodes which require insulation in the plane of the film.

According to a fourth aspect of the present invention, electrodes which face each other with a film sandwiched therebetween are adhered to each other, and a conductive film which electrically connects the electrodes is provided. And conductive particles for electrically connecting the electrodes to each other, and a non-conductive rod material mixed in the adhesive and separating the conductive particles in the surface direction of the conductive film. Is the gist.

A fifth aspect of the present invention is characterized in that the rod is oriented in the plane direction of the conductive film.
In the sixth invention, the gist is that the rod is oriented in a direction at right angles to the direction between electrodes adjacent to each other that require insulation in the plane of the film.

[0012]

According to the above construction, in the first invention,
Conductive particles and non-conductive rods are added and diffused to the adhesive of the conductive film. With this conductive film, electrodes facing each other with the film sandwiched therebetween are bonded,
The electrodes are electrically connected.

In the second invention, after the conductive particles and the non-conductive rod are added and diffused, the conductive film is stretched in the plane direction. In the third invention, stretching is performed in the plane of the film in a direction perpendicular to the direction between adjacent electrodes which require insulation.

In the fourth invention, the adhesive bonds both electrodes. Conductive particles are mixed in the adhesive,
This particle electrically connects both electrodes. Further, a non-conductive rod material is further mixed into the adhesive, and the conductive particles are separated by the rod material in the surface direction of the conductive film. Therefore, the electrodes are electrically connected to each other, and the insulating property in the plane direction of the conductive particles is improved.

In the fifth invention, the rod is oriented in the plane direction of the conductive film, and the rod separates between the conductive particles and between the conductive particles and the electrode. In the sixth invention, the rod is oriented in a plane at right angles to the direction between the electrodes adjacent to each other which requires insulation in the plane of the film, and by this rod, between the conductive particles and between the conductive particles and the electrode. The spaces are separated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an anisotropic conductive film having a film adhesion direction and a conductive direction different from each other and a manufacturing method thereof will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the glass substrate 1
A plurality of transparent electrodes 2 made of ITO (indium oxide) or the like are formed to extend in parallel on the upper side, and a flexible substrate 4 is bonded with a conductive film 3 interposed therebetween. A plurality of copper electrodes 5 are formed to extend in parallel on the surface of the flexible substrate 4 on the glass substrate side, and end portions of the copper electrodes 5 face the end portions of the transparent electrodes 2 on the glass substrate 1, respectively. It is arranged.

The conductive film 3 shown in FIG. 1 is mainly composed of a binder 6 made of resin, and conductive particles 7 are diffused in the binder 6 which is an adhesive. This conductive particle 7
Is a polymer particle plated with gold or nickel and has deformability. Furthermore, in the binder 6,
The glass fiber 8 formed in a rod shape, which is a rod material, is diffused.

The conductive particles 7a and the glass fiber 8a are pressed between the electrodes 2 and 5 facing each other, and the conductive particles 7a are deformed to electrically connect the electrodes 2 and 5.
On the other hand, the glass fiber 8a is hardly deformed, and the diameter of the glass fiber 8a determines the distance between the electrodes 2 and 5 and the degree of deformation of the conductive particles 7a.
The diameter of the conductive particles 7 is about 10 μm, and the diameter of the glass fiber 8 is about 4 μm. From the diameters of the conductive particles 7 and the glass fiber 8, it can be estimated that the degree of deformation of the conductive particles 7a is about 60%. The reliability of conductivity can be improved by deforming the conductive particles 7a by about 40 to 60% during bonding.

As shown in FIG. 3, the conductive particles 7 and the glass fibers 8 are oriented in the film plane at a right angle to the direction between adjacent electrodes which require insulation. The glass fiber 8 ensures insulation between the adjacent conductive particles 7 and insulation between the conductive particles 7 and the electrodes 2 and 5.

Next, the manufacturing method and the bonding method of this conductive film will be described in detail. As shown in FIG. 5A, the conductive particles 7 and the glass fiber 8 are provided in the resin binder 6.
Is added and diffused, and the binder 6 is formed into a film shape. In this state, the conductive particles 7 and the glass fiber 8 in the binder 6 are oriented in arbitrary directions. Then, as shown in FIG. 5B, this film is stretched by about 200% in a predetermined plane direction (direction of arrow). By this stretching, the conductive particles 7 and the glass fiber 8 in the binder 6 are oriented in the stretching direction. Even if the glass fiber 8 is not oriented, the conductive particles 7 can be separated from each other or the conductive particles 7 can be separated from the adjacent electrodes 2 and 5 to enhance the insulating property. However, when stretching is performed in the plane perpendicular to the direction between adjacent electrodes that require insulation in the plane of the film used for adhesion, the glass fibers 8 are rod-shaped, and therefore the conductive particles 7 are formed. Are separated by glass fibers 8 so that the insulation is better retained.

Next, a method of adhering the conductive film 3 will be described. This bonding is performed by a dedicated conductive film thermocompression bonding device. As shown in FIG. 4, the conductive film 3 formed as described above (a) is sandwiched between the glass substrate 1 and the flexible substrate 4. At this time, the conductive film thermocompression bonding apparatus is provided with a positioning stopper and a fine adjustment mechanism so that the copper electrode 5 is arranged to face the transparent electrode 2 accurately (b). Then, the substrates 1 and 4 are pressed against each other.

At this time, since the glass fibers 8 are rod-shaped, they may cross each other when they are diffused, but when the lengths are appropriately short, the substrates 1 and 4 are pressed to slip. The intersection state can be solved. Further, when the long glass fibers 8 overlap, the glass fibers 8 are crushed and the overlap is eliminated.

Then, the joint portions of the two substrates 1 and 4 are momentarily heated, the conductive particles 7a are pressed and crushed, and the two electrodes 2 and 5 are electrically connected (c). The glass fiber 8a has a high Young's modulus, is hardly deformed even when a load is applied, and has a small diameter variation, so that the distance between the electrodes 2 and 5 can be controlled with high accuracy. Therefore, the degree of deformation of the conductive particles 7a is accurately controlled, and the reliability of conduction between the electrodes 2 and 5 is extremely improved.

After that, the joining portion is cooled by the cooling air and the joining is completed. The two substrates 1 and 4 are kept joined by the force of the resin binder 6 that attracts the substrates. As described above in detail, since the glass fiber 8 for insulation is added to the binder 6 together with the conductive particles 7, the insulation between the electrodes 5 adjacent to each other is enhanced. Therefore, it is not necessary to apply an insulating film to the conductive particles 7, and high conductivity can be obtained between the opposing electrodes 2 and 5. Further, since the glass fiber 8 is rod-shaped, both electrodes 2, 5 can be supported by wires, and the distance between the electrodes 2, 5 can be controlled with higher accuracy. Therefore, the deformation rate of the conductive particles 7 is constant, and the reliability of the conductivity between the electrodes 2 and 5 can be improved.

Further, since the glass fiber 8 enhances the insulating property, even if the distance between the adjacent electrodes 5 becomes small, the conductive particles having a high mixing concentration and a large size can be used, and the opposing particles can face each other. The conductivity between the electrodes 2 and 5 can be further increased. Therefore, the current capacity is increased, and it has become possible to reduce the number of wires, such as a power supply line, which conventionally used two wires in parallel to one wire.

Further, since the glass fiber 8 is generally often used and only needs to be mixed in the binder 6, the cost can be reduced as compared with the case where the insulating film is applied to the conductive particles.

The present invention is not limited to the above-described embodiments, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the conductive particles are polymer particles plated with gold or nickel. However, metal particles such as gold, nickel, or solder, or conductive particles such as carbon may be used. .

(2) In the above embodiment, the cylindrical glass fiber is used as the non-conductive rod material, but the material may be changed to ceramics or the like, or the prismatic material may be used. .

[0030]

As described above in detail, according to the present invention, a low-cost conductive film having a high conductivity between the electrodes to be joined and a high insulation property between the adjacent electrodes and a method for manufacturing the same are provided. It has an excellent effect that it can be done.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a joined state of substrates by a conductive film in one example embodying the present invention.

FIG. 2 is a plan view showing a bonded state of a glass substrate and a flexible substrate.

FIG. 3 is a plan view schematically showing the orientation of conductive particles and glass fibers in a conductive film.

FIG. 4 (a) is a cross-sectional view schematically showing the conductive film after stretching. (B) It is sectional drawing which shows typically the electrically conductive film pinched | interposed between the glass substrate and the flexible substrate. (C) It is sectional drawing which shows typically the conductive film after compression heating by the conductive film thermocompression-bonding apparatus.

FIG. 5 (a) is a plan view schematically showing a state before stretching of the conductive film. (B) It is a top view which shows typically the orientation state after a conductive film is stretched.

FIG. 6 is a cross-sectional view schematically showing a joined state of substrates by a conductive film of a conventional example.

FIG. 7 is a cross-sectional view schematically showing a joined state of substrates by another conventional conductive film.

[Explanation of symbols]

3 ... Conductive film, 6 ... (adhesive) binder,
7, 7a ... Conductive particles, 8, 8a ... (fiber bar) glass fiber.

Claims (6)

[Claims] 1. A method of manufacturing a conductive film, comprising bonding electrodes facing each other with a film interposed therebetween and electrically connecting the electrodes, wherein conductive particles are used for the adhesive of the conductive film. And a method for producing a conductive film, which comprises adding and diffusing a non-conductive rod. 2. The method for producing a conductive film according to claim 1, wherein the conductive film and the non-conductive rod are added and diffused, and then the conductive film is stretched in a plane direction. 3. The method for producing a conductive film according to claim 2, wherein the film is stretched in a direction at a right angle to a direction between adjacent electrodes which require insulation in a film plane. 4. A conductive film for adhering electrodes facing each other with a film sandwiched therebetween and electrically connecting the electrodes, wherein an adhesive for adhering the both electrodes is mixed with the adhesive, Conductive particles for electrically connecting the both electrodes, and a non-conductive rod material mixed in the adhesive to separate the conductive particles in the surface direction of the conductive film. Conductive film. 5. The conductive film according to claim 4, wherein the bar member is oriented in the plane direction of the conductive film. 6. The conductive film according to claim 5, wherein the rod member is oriented in a plane at right angles to a direction between adjacent electrodes which require insulation in a plane of the film.