JPH07197001A - Anisotropically conductive thermosetting adhesive - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive which is safe, provides a high connection reliability, and enables an easy restoration of connection between terminals by compounding an insulating resin compsn. mainly comprising an epoxy resin and a curative with conductive particles having an elastic modulus higher than that of the compsn. at the temp. of press bonding. CONSTITUTION:This thermosetting adhesive is prepd. by compounding an insulating resin compsn. mainly comprising an epoxy resin and a curative with conductive particles having an elastic modulus higher than that of the compsn. at the temp. of press bonding. The adhesive is safe, provides a high connection reliability, and enables an easy restoration of connection between terminals. Coating the surfaces of the particles with the compsn. is effective in further improving the reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, TAB (Tap).
(e) Automated Bonding) and a thermosetting anisotropic conductive adhesive used for high-fine-pitch connection such as a liquid crystal display, and particularly to a regenerable thermosetting anisotropic conductive adhesive.

[0002]

2. Description of the Related Art Generally, in a liquid crystal display device, as shown in FIG.
1. A plurality of TABs 15 are formed by using an anisotropic conductive adhesive 14 containing conductive particles 13 with respect to the terminals 12 led out around 1.
The terminal 16 of is electrically connected. In this case, as the insulating adhesive substance 17 of the anisotropic conductive adhesive 14,
Thermosetting resins are mainly used in recent years because they lack electrical connection reliability.
If the thermosetting anisotropic conductive adhesive 14 is used, heat resistance and moisture resistance are improved, but on the other hand, a new problem occurs. That is, normally, the liquid crystal display body 11 and the TA
When connecting to B15, a large number of TABs 15 are pressure-bonded to the liquid crystal display body 11, so that a connection failure may occur due to misalignment or the like. In such a case, the TAB 15 is peeled off from the liquid crystal display body 11, the thermosetting anisotropic conductive adhesive 14 remaining on the terminals is removed, and the thermosetting anisotropic conductive adhesive is removed again. Liquid crystal display body 11 and TAB using agent 14
It is necessary to connect with 15.

[0003]

For this reason, reconnection (reproduction) has been conventionally performed by the following various methods, but each of them has various problems.

The first method is to remove the anisotropic conductive adhesive 14 remaining on the liquid crystal display body 11 using a solvent. In this case, examples of the solvent include acetone, toluene, ligroin, an epoxy stripping solvent (San-Econ G430 manufactured by Taiyo Kako Co., Ltd.), and a chlorine-based solvent surfactant. However, all of them have low viscosities, and penetrate into the TAB 15 which does not need to be regenerated, thus lowering the connection reliability. Further, there is a defect that a special exhaust device needs to be attached because the organic solvent is used.

A second method is to remove the anisotropic conductive adhesive 14 remaining on the liquid crystal display body 11 by using a peeling paste. That is, this is a method in which a mixture of a phenoxy resin in a mixed solvent of tetrahydrofuran (THF) / methanol is used as a peeling paste, and the residue is dissolved and removed by utilizing the film forming property of the phenoxy resin. This method is effective in preventing the penetration of the solvent, but it takes time because it needs to be left for 10 to 15 minutes.

As a third method, as shown in FIG. 4, a thermosetting anisotropic conductive adhesive 20 in which hard particles such as Ni are used as the conductive particles 19 is used, and the liquid crystal display main body 11 is used.
There is a method of pressing again from above the anisotropic conductive adhesive 14 remaining. This method can be performed easily, but since the anisotropic conductive adhesive 20 for reproduction only is used, two types of anisotropic conductive adhesives 14 and 20 must be prepared. , It becomes complicated in terms of inventory. Moreover, there is a problem in life in terms of frequency of use. Further, if the re-compression bonding is performed two or three times, the conductive particles 13, 19 of the anisotropic conductive adhesives 14, 20 remaining on the liquid crystal display body 11 increase and there is a risk of short-circuiting as shown in FIG.

As a fourth method, there is a method in which the anisotropic conductive adhesive 14 remaining on the liquid crystal display body 11 is mechanically shaved and a new anisotropic conductive adhesive 14 is pressure bonded. However, this easily damages the connection pattern, and peeling debris is generated to become a foreign substance, causing a defect. As described above, each of the above methods has advantages and disadvantages, and there is a demand for a method that is safe, has high connection reliability, and can be easily reproduced.

The present invention has been made in view of the above points of the prior art, and an object thereof is to provide a thermosetting anisotropic conductive material which is safe, has high connection reliability, and can be easily reproduced. It is to provide an adhesive.

[0009]

The present invention is a thermosetting anisotropic adhesive comprising an epoxy resin, an insulating resin containing a curing agent as a main component, and conductive particles in the insulating resin. It is characterized in that it contains conductive particles whose elastic modulus at temperature is higher than that of the insulating resin. In this case, it is also effective to coat the surface of the conductive particles with an insulating resin.

[0010]

In the present invention having such a constitution, since the conductive particles having a higher elastic modulus at the pressure bonding temperature than the insulating resin are contained, the conductive particles are not deformed even when the insulating resin is softened during thermocompression bonding. Therefore, if thermocompression bonding (regeneration) is performed again between the terminals using the present invention after peeling the adhesive, the insulating resin remaining between the terminals is pushed away by the conductive particles, and as a result, the connection between the terminals is surely performed. Be seen. In this case, if the surface of the conductive particles is coated with an insulating resin, short-circuiting between the conductive particles is unlikely to occur even when the number of conductive particles increases due to repeated regeneration, and a short-circuit between adjacent terminals is prevented. .

[0011]

EXAMPLES The thermosetting anisotropic conductive adhesive according to the present invention will be described below with reference to specific examples.

Preparation of Thermosetting Anisotropic Conductive Adhesive 1 First, an insulating resin 2 as a binder having the following composition was prepared. Epoxy resin Epicoat 1009 (made by Yuka Shell Epoxy Co., Ltd.) 100 parts by weight Curing agent HX3941HP (made by Asahi Kasei) 170 parts by weight Toluene 80 parts by weight

The elastic modulus of the insulating resin 2 at 170 ° C. was 2 × 10 ⁸ dyn / cm ² . In this case, the elastic modulus was measured by using Rheo Vibron DDV-01FP manufactured by Orientec Co., Ltd. under the conditions of a frequency of 60 Hz and a temperature rising speed of 3 ° C./min.

Next, the following conductive particles 3 were mixed into this insulating resin 2 to form a film having a thickness of 25 μm.

A: Ni particles having an average particle size of 7 μm (Example 4) 54 parts by weight B: Particles obtained by coating the particles of A with an acrylic / styrene resin in an amount of 0.1 to 0.2 μm by the method of the following * (Example) 1) 54 parts by weight C: Particles obtained by plating Ni / Au on silica having an average particle size of 5 μm (Example 5) 14 parts by weight D: C particles having an acrylic / styrene resin content of 0.1 to 0.1 by the method described below. Particles coated with 0.2 μm (Example 2) 14 parts by weight E: Particles obtained by applying Ni / Au plating to a benzoguanamine resin having an average particle size of 5 μm (Nippon Kagaku Co., Ltd. Bright 20GNRY4.6EH Example 6) 14 parts by weight F : Particles obtained by coating the particles of E with acrylic / styrene resin in an amount of 0.1 to 0.2 μm by the method described below (Example 3) 14 parts by weight G: Ni / Au plating on crosslinked polystyrene having an average particle size of 5 μm Particles (Comparative Example 1) 14 parts by weight H: Particles obtained by coating the particles of G with a crosslinked polystyrene resin in an amount of 0.1 to 0.2 μm by the following method * (Comparative Example 2) 14 parts by weight

*: Acrylic / styrene resin was mixed with conductive particles 3 at a ratio of 5: 100 using a hybridization system (manufactured by Nara Machinery Co., Ltd.), and the rotation speed was 16200 r.
It was treated with pm for 10 minutes.

The elastic moduli of the above conductive particles 3 at 170 ° C. were as follows. In this case, the elastic modulus was measured under the same conditions as the insulating resin 2. A, B: 2 × 10 ¹² dyn / cm ² C, D: 6 × 10 ¹¹ dyn / cm ² E, F: 4 × 10 ⁸ dyn / cm ² G, H: 9 × 10 ⁷ dyn / cm ²

Preparation of TAB 4 Next, a copper foil having a thickness of 35 μm is attached to a polyimide film 5 having a thickness of 75 μm (Upilex manufactured by Ube Industries, Ltd.) with an adhesive, and a conductor width of 50 μm and a pitch of 100 μm.
To obtain 130
Solder plating was applied to the terminal 6 of the pin to prepare the TAB 4.

Liquid Crystal Display Main Body 7 On the other hand, for a liquid crystal display, a glass 9 having an ITO pattern 8 having a conductor width of 50 μm and a pitch of 100 μm was prepared.

Connection Using the films of the above-mentioned Examples and Comparative Examples, the glass 9 and the TAB 4 were subjected to thermocompression bonding under the conditions of a temperature of 170 ° C., a pressure of 40 Kgf / cm ² and a time of 20 seconds as shown in FIG. 2A. A sample was prepared by connecting and the initial characteristics and aging characteristics were measured.

Regeneration Furthermore, using the sample in the above thermocompression bonded state, TAB4 was applied while applying heat of 130 to 140 ° C. from the glass 9 side.
After peeling off (see FIG. 2B), a new TAB4 was thermocompression-bonded again using the same anisotropic conductive adhesive 1 under the above-mentioned conditions (see FIG. 2C), and the initial conduction resistance after reproduction and the conduction after aging were conducted. The resistance was measured. And this process was repeated. The results of these measurements are shown in Table 1.

[0022]

[Table 1]

As can be seen from Table 1, the crimping temperature (1
In Examples 1 to 3 in which the elastic modulus of the conductive particles 3 at 70 ° C.) is higher than that of the insulating resin 2 as the binder, the conduction characteristics after regeneration were good. This is as shown in FIG.
This is because the conductive particles 3a and 3b are not deformed at the time of reproducing and pressure bonding, and the insulating resin 2 is pushed away by this and the connection between the terminal 6 and the ITO pattern 8 is surely made. Also,
Since the conductive particles 3 were covered with the insulating resin, a short circuit did not occur between the adjacent terminals even after 3 times of reproduction.

On the other hand, in Examples 4 to 6 in which the elastic modulus of the conductive particles 3 at the above-mentioned pressure bonding temperature is higher than that of the insulating resin 2 of the binder and the insulating film is not applied, the conduction resistance after regeneration is good, A short circuit did not occur between the adjacent terminals after the first and second reproduction. However, a short circuit occurred between the adjacent terminals after three times of reproduction.

Further, in the case of Comparative Example 1 in which the elastic modulus of the conductive particles 3 at the above-mentioned pressure bonding temperature is lower than that of the insulating resin 2 as the binder, the conduction resistance after reproduction deteriorated. This is because, for example, as shown in FIG. 1B, when the insulating resin 2 is softened in the pressure bonding step, the conductive particles 3c and 3d are also deformed, and the insulating resin 3 on the ITO pattern 8 cannot be pushed away.
Further, in the case of Comparative Example 1, since the conductive particles 3 were not coated with an insulating film, a short circuit occurred between adjacent terminals after three times of reproduction.

Further, the conductive particles 3 at the above-mentioned pressure bonding temperature
In the case of Comparative Example 2 in which the elastic modulus of is lower than that of the insulating resin 2 as the binder and the insulating film is applied, a short circuit between adjacent terminals did not occur after 3 times of regeneration, but Comparative Example 1
For the same reason as above, the conduction resistance after regeneration increased.

The present invention is not limited to the above-mentioned embodiment, but various modifications can be made. For example, various materials can be used as the insulating resin and the conductive particles. In addition, different anisotropic conductive adhesives can be used for the initial pressure bonding and the pressure bonding during reproduction. However, it is of course necessary that the elastic modulus at the crimping temperature of the conductive particles of the anisotropic conductive adhesive used at the time of regeneration must be higher than the elastic modulus at the crimping temperature of the insulating resin of the first anisotropic conductive adhesive. Is.

[0028]

As described above, according to the present invention, since conductive particles having a higher elastic modulus at the crimping temperature than that of the insulating resin are contained, the connection between the terminals can be performed easily and with high reliability. Connection playback can be performed. In this case, the connection reliability can be further improved by coating the surface of the conductive particles with an insulating resin.

Moreover, according to the present invention, it is not necessary to remove the anisotropic conductive adhesive remaining on the terminals, so that the recycling process can be shortened. Further, since the same anisotropic conductive adhesive as that used for the adhesion can be used for the reproduction, it is possible to prevent the anisotropic conductive adhesive from being mistaken. Furthermore, according to the present invention, reproduction can be performed without adversely affecting other parts.

[Brief description of drawings]

FIG. 1A is an explanatory cross-sectional view showing the action of Examples 1 to 3 of the present invention. B is an explanatory view showing the action of Comparative Examples 4 and 5 of the present invention.

FIG. 2 is a sectional view showing an example of a reproducing method using the present invention.

FIG. 3 is a schematic perspective view showing a method of connecting the A liquid crystal display main body and the TAB. B is a cross-sectional view showing a method of connecting the liquid crystal display body and the TAB.

FIG. 4 is a sectional view showing a conventional reproducing method.

FIG. 5 is a cross-sectional view showing a state in which a short circuit has occurred in the conventional reproducing method.

[Explanation of symbols]

 1 Anisotropic Conductive Adhesive 2 Insulating Resin 3 (3a, 3b) Conductive Particles 4 TAB 5 Polyimide Film 6 Terminal 7 Liquid Crystal Display Main Body 8 ITO Pattern 9 Glass

Claims (2)

[Claims] 1. A thermosetting anisotropic adhesive comprising an epoxy resin, an insulating resin containing a curing agent as a main component, and conductive particles contained in the insulating resin, wherein the elastic modulus at the pressure bonding temperature is the above-mentioned insulating property. A thermosetting anisotropic conductive adhesive containing conductive particles higher than a resin. 2. The thermosetting anisotropic conductive adhesive according to claim 1, wherein the surface of the conductive particles is coated with an insulating resin.