JPS61195179A - Anisotropically conductive adhesive sheet - Google Patents

Abstract

PURPOSE:To obtain the titled sheet capable of simultaneously accomplishing insulating protection of liquid crystal display and driving module and electrical connection between them, by forming, on one side of releasable flexible film, an insulating synthetic resin layer and conductive powder-contg. specific synthetic resin layer thereon. CONSTITUTION:The objective sheet can be obtained by forming, (A) on one side of a releasable flexible film, (B) the first insulating synthetic resin layer and thereon, (C) the second synthetic resin layer with the softening point higher than that of the first layer, also containing conductive powder (e.g., metallic powder carbon powder). Preferably, the softening points of the components (B) and (C) are <80 deg.C and >=80 deg.C, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used to electrically connect two electrical components having high-density terminal leads, such as electrically connecting a liquid crystal display device and a drive module. The present invention relates to an anisotropically conductive adhesive sheet that can be used as an anisotropically conductive adhesive sheet.

2. Description of the Related Art In recent years, the development of liquid crystal display devices has been remarkable, and various methods of electrically connecting these liquid crystal display devices and drive modules have been studied, and anisotropically conductive adhesive sheets are often used.

FIG. 3 is a sectional view showing a conventional anisotropically conductive adhesive sheet. In Fig. 3, 1 is a binder made of a thermoplastic resin or a thermoplastic resin and a thermosetting resin, and 2 is a conductive powder.The conductive powder 2 is dispersed in the binder 1, and the sheet is The anisotropically conductive adhesive sheet 3 is obtained by heating and drying the adhesive sheet 3. FIG. 4 is a sectional view showing a state in which a liquid crystal display device and a drive module are connected using such a conventional anisotropically conductive adhesive sheet 3. In FIG. 4, 4 is a glass substrate constituting a liquid crystal display device, 6 is a transparent electrode provided on the glass substrate 4, 6 is a flexible substrate (hereinafter referred to as FPC) that connects the drive module, and 7 is a space between the glass substrates 4. This is a sealing resin for enclosing a liquid crystal (not shown) inserted into the housing.

Problems to be Solved by the Invention In the above structure, the transparent electrode of the liquid crystal display device is
As shown in the figure, it is not completely covered and is exposed, and the conductor part of the FPC connected to the transparent electrode is also exposed, resulting in short-circuits due to adhesion of dust, etc., short-circuit breakage of the transparent electrodes in humidity, etc. It had the disadvantage of causing

The present invention aims to eliminate such conventional drawbacks, and provides an anisotropically conductive adhesive sheet that can perform insulation protection of the transparent electrode of a liquid crystal display device and the conductor part of an FPC at the same time as electrical connection. The purpose is to

Means for Solving the Problem In order to solve this problem, the anisotropic conductive adhesive sheet of the present invention has a flexible film having a release effect, and
An insulating first synthetic resin layer and a second synthetic resin layer containing conductive powder and having a higher softening point than the first synthetic resin layer are formed on the first synthetic resin layer. It is characterized by:

With this configuration, for example, in connection between a liquid crystal display device and an FPC, electrical connection is made with the second synthetic resin layer containing conductive powder with a high softening point, and the first synthetic resin layer with insulating properties with a low softening point is connected. The resin layer can provide insulation protection for the transparent electrode of the liquid crystal display device and the conductor portion of the FPC.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view showing an embodiment of the anisotropically conductive adhesive sheet of the present invention. In FIG. 2, 8 is a flexible film subjected to mold release treatment, and 9 is a first synthetic resin layer having insulation properties formed on the entire surface of the film 8, such as polyester having a softening point of 120° C. or lower. Vylon GK-130 (manufactured by Toyobo Co., Ltd.) can be used as the resin. 10 is a second synthetic resin layer formed on the first synthetic resin layer 9 and made by dispersing conductive powder 11, and the softening point of this second synthetic resin layer 10 is equal to the softening point of the first synthetic resin layer 9. It is higher than that of synthetic resin M9. This second
For example, the synthetic resin layer 1o has a softening point of 120 to 1
Byron GK-103 as polyester resin at 80℃
(manufactured by Toyobo Co., Ltd.) can be used, and as the conductive powder 11, tin oxide T-1 (manufactured by Mitsubishi Metals Co., Ltd.) can be used.
can be used. As this conductive powder 11,
Metal powder, carbon powder, etc. can also be used.

FIG. 1 shows a transparent electrode for a lead-out of a liquid crystal display device and an FPC for a lead-out using the anisotropically conductive adhesive sheet of the present invention described above.
FIG. 3 is a cross-sectional view showing a connected state. In Figure 1,
12 is a glass substrate constituting a liquid crystal display device; 13 is a transparent lead-out electrode provided on the glass substrate 12; 14
016 is an FPC (flexible board) for drawers, and may be formed by screen printing commercially available conductive paste on polyethylene terephthalate with a thickness of 38 μm, for example, and a metal film formed by vapor deposition or the like can also be used as the conductor part. is a sealing resin for enclosing the liquid crystal,
Reference numeral 16 denotes a heat compression bonding tool used for connection.

Now, the anisotropically conductive adhesive sheet configured as shown in FIG. 2 is placed on the FPC 14 at 160°C and 3oK4/cd.

After temporarily fixing for 6 seconds, peel off the flexible film 8,
FPC facing transparent electrode 13 for extraction of liquid crystal display device
14 conductor parts were aligned, and one end of the FPC 14 was heat-pressed to the glass substrate 12 at 160C, 30:4/cIIF, and 4 seconds using the heat-pressure bonding tool 16. By this crimping, the insulating first synthetic resin layer 9 with a low softening point flows out, and as shown in FIG. 1, this first synthetic resin layer 9 covers and protects the surface of the transparent electrode 13 around the connection part. It was observed using a microscope. Of course, the first synthetic resin layer 9 is formed on the FPC 14 other than at one end of the FPC 14.
It is fixed together with the second synthetic resin layer 10 at necessary locations. On the other hand, the conductive powder 10 is dispersed 7' (the second synthetic resin layer 10 provides an electrical connection between the transparent electrode 13 and the conductor part of the FPC 14, and a mechanical connection between the transparent electrode 13 and the FPC 14). Ta.

And humidity load [40℃×76%RH, DCav)6
Even at the oo time, it was confirmed that the transparent electrode 13 was not disconnected and the short circuit was not caused.

Furthermore, when the anisotropically conductive adhesive sheet of the present invention was laminated onto the surface of an FPC (80'C, 2m/min) and the insulation resistance of the pattern surface was measured, a value of 1 x 10''Ω or more was obtained, and the insulation resistance of the pattern surface was measured. We were able to apply insulation coating.

As is clear from the above description, the feature of the anisotropic conductive adhesive sheet of the present invention is that there is a difference in the softening point of the first synthetic resin layer and the softening point of the second synthetic resin layer, As mentioned above, the softening point of the second synthetic resin layer is higher than that of the first synthetic resin layer. In addition, if the first synthetic resin layer has a softening point of less than 8C), problems tend to occur in durability when used in products, and similarly, if the second synthetic resin layer has a softening point of over 180C, it will not be heated. It was confirmed that the heat during pressure heating tends to affect other electrical components. As a result of research conducted by the inventors, it has become clear that the first and second synthetic resin layers having a difference in softening point of 10 to 30'C show good results.

In addition, 1. It was confirmed that polyester resin, which is a thermoplastic resin used in the above examples, is suitable for the second synthetic resin layer.

Effects of the Invention As is clear from the above explanation, by using the anisotropically conductive adhesive sheet of the present invention, the second synthetic resin layer containing conductive powder with a high softening point can be used for, for example, liquid crystal display devices and drawers. Electrical connection can be made when connecting the FPC, and at the same time, the transparent electrode of the liquid crystal display device and the conductor portion of the FPC can be insulated and protected using the insulating first synthetic resin layer with a low softening point. For example, when a conventional anisotropically conductive adhesive sheet is used, a humidity load (40°C x 95%RH) is applied.

DCaV) After 100 hours, 70 to 80% of the transparent electrodes will break, and in order to prevent this, conventional methods have required either sealing the entire liquid crystal display or covering the transparent electrodes other than the bonded areas with insulation. did not become. However, by using the anisotropic conductive adhesive sheet of the present invention, it is possible to create an insulating protective film for transparent electrodes at the same time as electrical connection, thereby improving the reliability of liquid crystal display devices. 1. Reducing work steps and costs. Effects such as this can be obtained. Furthermore, by covering the conductor surface of the FPC with the anisotropically conductive adhesive sheet of the present invention, insulation protection of the FPC surface can be performed, and an effect of preventing short circuits caused by dust or the like can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a connection state between a liquid crystal display device and an FPC using the anisotropically conductive adhesive sheet of the present invention, and FIG. 2 is a sectional view showing an embodiment of the anisotropically conductive adhesive sheet of the present invention. , Figure 3 is a sectional view showing a conventional anisotropically conductive adhesive sheet, Figure 4 is a cross-sectional view showing a conventional anisotropically conductive adhesive sheet.
The figure is a cross-sectional view showing a connection state between a liquid crystal display device and an FPC using the same adhesive sheet. 8... Flexible film, 9... First synthetic resin layer, 1o... Second synthetic resin layer, 11
・・・・・・Conductive powder. Name of agent: Patent attorney Toshio Nakao and 1 other person11
, Figure 2 of the proverb based on the -8 guide.

Claims (2)

[Claims] (1) An insulating first synthetic resin layer on one main surface of a flexible film having a mold release effect, and the above-mentioned first synthetic resin containing conductive powder on the first synthetic resin layer. An anisotropically conductive adhesive sheet comprising a second synthetic resin layer having a higher softening point than the first layer. (2) Anisotropic conductivity according to claim 1, characterized in that the first synthetic resin layer has a softening point of 80° C. or higher, and the second synthetic resin layer has a softening point of less than 180° C. Adhesive sheet.