JPH05334912A - Anisotropic conductive adhesive and conductive connection structure - Google Patents

Abstract

PURPOSE:To enlarge an area of a conductive particle in contact with connecting terminals and easily provide an anisotropic conductive adhesive at a low cost. CONSTITUTION:In an anisotropic conductive adhesive 1, a thermoplastic insulative resin film 3 covering a conductive particle 2 made of a conductive polymer is contained in an insulative adhesive 4 at equal intervals. When a connecting terminal 12 of a transparent substrate 11 and a connecting terminal 14 of a TAB tape 13 are thermally fitted to each other for connection by the anisotropic conductive adhesive 1, a part of the insulative resin film 4 in the pressurizing direction is fluidly relieved so that the conductive particle 2 is elastically deformed to be thus brought into contact in a suitably compressed state with the pair of connecting terminals 12, 14 facing to each other, thereby resulting in a large contact area. Since the conductive particle 2 is made of a conductive polymer, it is possible to easily manufacture the adhesive at a low cost in comparison with the prior art where an elastic resin particle is covered with a metal plating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic conductive adhesive and a conductive connection structure using the anisotropic conductive adhesive.

[0002]

2. Description of the Related Art In a liquid crystal display device, for example, a connection terminal of a liquid crystal display panel (a connection terminal of one electronic component) is connected to a semiconductor chip for driving the liquid crystal display panel or a TAB tape on which the semiconductor chip is mounted. When conductively connecting a terminal (connecting terminal of the other electronic component) to each other, an anisotropic conductive adhesive obtained by mixing conductive particles in an insulating adhesive may be used. In such an anisotropic conductive adhesive, when it is interposed between the connection portion including the connection terminal of one electronic component and the connection portion including the connection terminal of the other electronic component and thermocompression bonded, Has conductivity due to the action of conductive particles, but has insulation due to the action of an insulating adhesive in the direction orthogonal to the pressing direction,
In addition, a connecting portion including a connecting terminal of one electronic component and a connecting portion including a connecting terminal of the other electronic component are bonded with an insulating adhesive. In this case, as the conductive particles, metal particles alone or elastic resin particles having a surface coated with a metal plating film are used.

[0003]

However, in such an anisotropic conductive adhesive of the related art, when metal particles alone are used as the conductive particles, the conductive particles are crushed even if pressure is applied during thermocompression bonding. Without contacting the original shape without contacting with a pair of connection terminals facing each other, the contact area of the conductive particles to the connection terminal is small,
Therefore, there is a problem that the reliability of the conductive connection is poor.
On the other hand, in the case where the conductive particles having the metal plating film provided on the surface of the elastic resin particles are used, the metal plating film elastically deforms together with the elastic resin particles, so that the contact area of the metal plating film with respect to the connection terminal is reduced. Although it can be increased, there are problems that the number of steps involved in the plating process is large, the cost is high, and it is difficult to select the material of the elastic resin particles to be plated. Further, in either case, if the pressure applied during thermocompression bonding is too large, cracks may occur in the metal particles alone or in the metal plating film. In addition, when a thermoplastic type insulating resin film is provided on the surface of the conductive particles as described above, and the insulating resin film in the pressing direction flows and escapes when thermocompression-bonded, In addition to ensuring conductivity, the insulating resin film in the direction orthogonal to the pressing direction is left as it is on the surface of the conductive particles to ensure the insulation in the direction orthogonal to the pressing direction. However, even in this case, the same problem as above was encountered. The purpose of this invention is
An anisotropic conductive adhesive that can increase the contact area of the conductive particles to the connection terminal, can be easily obtained at low cost, and can prevent the conductive particles from cracking easily, and An object is to provide a conductive connection structure using this anisotropic conductive adhesive.

[0004]

An anisotropic conductive adhesive according to a first aspect of the present invention is one in which conductive particles, at least the surface of which is made of a conductive polymer, are mixed in an insulating adhesive. An anisotropic conductive adhesive according to a second aspect of the invention is one in which a thermoplastic insulating resin film is provided on the surface of the conductive particles. In the conductive connection structure according to claim 3, the anisotropic conductive adhesive according to claim 1 or 2 is interposed between a pair of connection terminals facing each other,
The pair of connection terminals are conductively connected via the conductive particles in the anisotropic conductive adhesive.

[0005]

According to the present invention, since the conductive polymer forming at least the surface of the conductive particles has flexibility, the conductive particles are elastically deformed and appropriately deformed when pressure is applied during thermocompression bonding. In the crushed state, they come into contact with a pair of connection terminals facing each other. Therefore, the contact area of the conductive particles with respect to the connection terminal can be increased, and the cost can be easily obtained at low cost. It is possible to prevent the conductive particles from being cracked even if the pressure applied in is too large.

[0006]

FIG. 1 shows an anisotropic conductive adhesive according to an embodiment of the present invention. This anisotropic conductive adhesive 1
Is a mixture of conductive particles 2 made of a conductive polymer such as polypyrrole, polythiophene, polyaniline, etc., on which a thermoplastic insulating resin film 3 is provided, which is uniformly mixed in an insulating adhesive 4. ing. Here, an example of a method for producing the conductive particles 2 made of a conductive polymer will be described. First, a monomer (pyrrole) is formed into particles by an emulsion polymerization method or the like. The monomer particles thus obtained may contain a solvent (methanol) or may be one obtained by evaporating the solvent. on the other hand,
An oxidizing agent (ferric chloride), a reducing agent (ferrous chloride), and a binder polymer (polyvinyl acetate) are dissolved in a solvent (methanol). Then, both are mixed and stirred to polymerize while adjusting the oxidation potential. After a certain period of time, the mixed solution is transferred onto a glass substrate. Next, the solvent is evaporated in a nitrogen gas atmosphere to obtain conductive polymer (polypyrrole) particles. Thus, the conductive particles 2 made of a conductive polymer are obtained. The conductive particles 2 thus obtained
When a thermoplastic insulating resin is attached to the surface of the above, a thermoplastic insulating resin film 3 is provided on the surface of the conductive particles 2 made of a conductive polymer. The insulating adhesive 4 is made of thermoplastic resin, thermosetting resin, or a mixture of both resins. When the insulating adhesive 4 is made of a thermoplastic resin, the softening temperature of the insulating resin film 3 is equal to or lower than the softening temperature of the insulating adhesive 4. When the insulating adhesive 4 is made of a thermosetting resin, the softening temperature of the insulating resin film 3 is lower than the curing temperature of the insulating adhesive 4.

FIG. 2 shows an example of a conductive connection structure using the anisotropic conductive adhesive 1. In this example, the ITO provided on the upper surface of the transparent substrate 11 of the liquid crystal display panel
And the connection terminal 14 provided on the lower surface of the TAB tape 13 having a semiconductor chip (not shown) mounted thereon are electrically connected to each other. In this case, first, the anisotropic conductive adhesive 1 is placed on the upper surface of the connection portion including the connection terminals 12 of the transparent substrate 11, and the TAB tape 13 is placed on the upper surface of the placed anisotropic conductive adhesive 1. The connection portion including the connection terminal 14 of is placed. When the connection portion of the transparent substrate 11 including the connection terminal 12 and the connection portion of the TAB tape 13 including the connection terminal 14 are thermocompression bonded,
A part of the insulating adhesive 4 in the anisotropic conductive adhesive 1 flows and escapes, and a part of the insulating resin film 4 in the pressing direction flows and escapes. A part of the conductive particles 2 in 1 comes into contact with both the connection terminal 12 of the transparent substrate 11 and the connection terminal 14 of the TAB tape 13 facing the connection terminal 12, whereby the connection terminal 12 of the transparent substrate 11 and the TAB are connected. The connection terminal 14 of the tape 13 is electrically conductively connected, and the insulating adhesive 4 is solidified, so that the connection portion including the connection terminal 12 of the transparent substrate 11 and the TAB tape 1 are formed.
3 and the connection portion including the connection terminal 14 are bonded.

By the way, since the conductive particles 2 are made of a conductive polymer having flexibility, the conductive particles 2 are elastically deformed and appropriately crushed to face each other when being pressed during thermocompression bonding. Since the pair of connection terminals 12 and 14 come into contact with each other, the contact area of the conductive particles 2 with respect to the connection terminals 12 and 14 is increased, and thus the reliability of conductive connection can be improved. In this case, the conductive particles 2 made of a conductive polymer are constantly subjected to a force to elastically return to the unloaded state, that is, the original state. Since the terminals 12 and 14 are pressed together, the reliability of the conductive connection can be further improved. In addition, since the conductive particles 2 are formed of a conductive polymer, they can be easily obtained at a low cost as compared with a conventional elastic resin particle provided with a metal plating film on its surface. Further, even if the pressure applied during thermocompression bonding is too large, it is possible to prevent the conductive particles 2 from being easily cracked.

Next, FIG. 3 shows an anisotropic conductive adhesive in another embodiment of the present invention, and FIG. 4 shows an example of the conductive connection structure. In these figures, parts having the same names as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be appropriately omitted. The conductive particles 2 of the anisotropic conductive adhesive 1 are formed by providing a conductive polymer film 6 on the surface of a core 5 made of a polymer that is more easily deformed by heat than a conductive polymer. On the surface of the conductive polymer film 6, the thermoplastic insulating resin film 3 is formed as in the case of the above-described embodiment.
Is provided. Then, using this anisotropic conductive adhesive 1, the connection terminals 12 of the transparent substrate 11 and the TAB tape 13 are formed.
When the conductive particles 2 are electrically connected in a state of facing each other, the conductive particles 2 are further elastically deformed and are not destroyed.
The contact area with respect to 2 and 14 is further increased, and the reliability of the conductive connection can be further improved.

In each of the above embodiments, the thermoplastic insulating resin film 3 is provided on the surface of the conductive particles 2, but this surely ensures the insulating property in the direction orthogonal to the pressing direction. The insulating resin film 3 may be omitted if the insulating property in the direction orthogonal to the pressing direction can be reliably ensured.

[0011]

As described above, according to the present invention, since the conductive polymer forming at least the surface of the conductive particles has flexibility, it becomes conductive when pressed during thermocompression bonding. The particles are elastically deformed and come into contact with a pair of connecting terminals facing each other in an appropriately crushed state, so that the contact area of the conductive particles with respect to the connecting terminals can be increased, and at a low cost and easily obtained. Even if the pressure applied during thermocompression bonding is too large,
It is possible to prevent the conductive particles from being easily cracked.

[Brief description of drawings]

FIG. 1 is a sectional view of an anisotropic conductive adhesive according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the connection terminals of the transparent substrate of the liquid crystal display panel and the connection terminals of the TAB tape are conductively connected by using the anisotropic conductive adhesive of this embodiment.

FIG. 3 is a sectional view of an anisotropic conductive adhesive according to another embodiment of the present invention.

FIG. 4 is a schematic view of the anisotropic conductive adhesive of another embodiment.
Sectional drawing of the state which electrically connected the connection terminal of the transparent substrate of the liquid crystal display panel, and the connection terminal of the TAB tape.

[Explanation of symbols]

 1 Anisotropic Conductive Adhesive 2 Conductive Particles 3 Insulating Resin Film 4 Insulating Adhesive 11 Transparent Substrate 12 Connection Terminal 13 TAB Tape 14 Connection Terminal

Claims (3)

[Claims] 1. An anisotropic conductive adhesive characterized in that conductive particles, at least the surface of which is made of a conductive polymer, are mixed in an insulating adhesive. 2. The anisotropic conductive adhesive according to claim 1, wherein a thermoplastic type insulating resin film is provided on the surface of the conductive particles. 3. A pair of connecting terminals facing each other.
Alternatively, the anisotropic conductive adhesive described in 2 is interposed, and the pair of connection terminals are conductively connected via the conductive particles in the anisotropic conductive adhesive.