JPH0411225A - Terminal connecting method for liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve the adhesive strength between the end part of a glass substrate and the end part of a flexible substrate by interposing a silane coupling agent between the glass substrate end part and an anisotropic conductive film. CONSTITUTION:Driving elements 3a and 4a mounted on flexible substrates 3 and 4 are connected to transparent electrodes 2a led out to the end parts of glass substrates 1 and 2 through metallic electrodes 2a and 3b formed on the flexible substrates 3 and 4. Then the glass substrate end parts are coated with the silane coupling agent 8, the anisotropic conductive film 9 where conductive particles are dispersed in an adhesive is stuck on the coating part, and the end parts of the flexible substrates 3 and 4 are superposed and aligned on the sticking part and pressed while the superposed part is heated. Consequently, the coupling force between the glass surfaces of the end parts of the glass substrates 1 and 2 and the adhesive in the anisotropic conductive film 9 is improved through the operation of the silane coupling agent 8. Consequently, the adhesive strength between the glass substrate end parts and flexible substrate end parts is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for connecting terminals of liquid crystal display elements, which are mainly used in personal computers, word processors, and the like.

(B) Conventional technology Conventionally, in this type of terminal connection method, an anisotropic conductive film is attached to the edge of a glass substrate of a liquid crystal display element, and the edge of a flexible substrate is superimposed on the attached part, and pressure is applied while heating. , and are trying to connect the two.

(c) Problems to be Solved by the Invention However, the terminal portions connected by this conventional method have a problem in that the adhesive strength varies greatly and lacks reliability.

This invention was made in consideration of the above circumstances, and at least the end of the glass substrate and the end of the flexible substrate are bonded by interposing a silane coupling agent between the end of the glass substrate and the anisotropic conductive film. The present invention provides a method for connecting terminals of a liquid crystal display element, which can improve adhesive strength with parts.

(d) Means for Solving the Problems This invention connects a driving element mounted on a flexible substrate to a transparent electrode drawn out at the end of a glass substrate via a metal electrode formed on the flexible substrate. A method for connecting terminals of a liquid crystal display element includes a step of applying a silane coupling agent to an edge of a glass substrate, a step of adhering an anisotropic conductive film in which conductive particles are dispersed in an adhesive to the applied part, and a step of applying the anisotropic conductive film in which conductive particles are dispersed in an adhesive. This is a terminal connection method for a liquid crystal display element, which is characterized by comprising a step of overlapping and positioning an end portion of a flexible substrate over a portion, and a step of applying pressure while heating the overlapping portion.

(E) Function After a silane coupling agent is applied to the glass substrate terminal and an anisotropic conductive film is attached thereon, the flexible substrate terminal is stacked on top of the silane coupling agent, so that the glass surface at the edge of the glass substrate and the anisotropic conductive film The bonding strength with the adhesive contained in the silane coupling agent is improved by the action of the silane coupling agent, thereby increasing the adhesive strength between the edge of the glass substrate and the edge of the flexible substrate.

(f) Examples Hereinafter, the present invention will be described in detail based on examples shown in the drawings. This invention is not limited by this.

Embodiment (1) FIG. 1 is a top view of a liquid crystal display panel showing an embodiment of the present invention, l is an upper glass substrate of the liquid crystal display panel,
2 is a lower glass substrate; 3 is a base film on which a driving LSI element 3a is mounted and has electrodes printed to draw out its input/output terminals; the end of the base film 3 is bonded to the lower substrate 2; . 4 is a base film on which a driving LSI element 4a is mounted, similar to the base film 3, and is bonded to the edge of the upper glass substrate l.

FIG. 2 is an enlarged top view of the base films 3 and 4, in which 5 is an output terminal section and 6 is an input terminal section. Note that the base film 3.4 includes, for example, a T film made of copper foil plated on a polyimide film with a thickness of 75 to 125 μm.
A B (Tape Automated Bondi
ng) Substrates with electrodes formed, flexible wiring boards (
FPC) etc. are used.

FIG. 3 is a perspective view showing the structure of the connecting portion between the lower glass substrate 2 and the base film 3, and FIG. 4 is a sectional view of the main part of FIG. 3. A method of connecting the glass substrate and the base film will be explained using these figures.

The liquid crystal display panel of this example has 1024 x 768 dots, and the transparent electrodes 2a with a width of 0.09zi+ have a pitch of 0.
．． 18U is drawn out to the end of the lower glass substrate 2.

Note that 7 is a sealing material for sealing the liquid crystal between the glass substrates 1 and 2.

First, the silane coupling agent 8 is applied to the edge of the glass substrate 2. As the silane coupling agent 8, KBE-903 manufactured by Shin-Etsu Chemical Co., Ltd. is used, which has a chemical name of γ-aminopropyltriethoxysilane and is manufactured by HJ
It is represented by the chemical formula CJ-3i(OCtH-)s.

Next, a thermosetting type anisotropic conductive film 9 is deposited thereon. This anisotropic conductive film is made by dispersing conductive particles in a binder (epoxy adhesive), and has a thickness of, for example, 15 to 15 mm.
AC-6071 manufactured by Hitachi Chemical Co., Ltd. with a thickness of 30 μm is used.

Next, the transparent electrode 2a of the glass electrode 2 and the base film 3
Align the electrodes so that they overlap.

Next, this end is heated at a temperature of 170°C, and
Pressurize by applying a pressure of 20 kg/cm.

FIG. 4 is a sectional view of the crimped portion, in which the electrode 3b of the base film 3 and the transparent electrode 2a are electrically connected via the conductive particles 9a contained in the anisotropic conductive film 9. Since the glass surface of the glass substrate 2 and the epoxy adhesive contained in the anisotropic conductive film 9 are bonded via the silane coupling agent 9, the adhesive force between the adhesive and the glass surface is increased by the silane coupling agent. increases due to the action of

The reliability of the liquid crystal display panel manufactured in this manner was confirmed.

First, it was placed in a high-temperature, high-humidity tank with a temperature of 65° C. and a humidity of 95% RH, and changes in adhesive strength were confirmed. The results are shown in FIG.

Figure 5 (a) shows a liquid crystal display panel manufactured by the method of this example, that is, one in which the terminals were connected using a silane coupling agent, and (b) shows a liquid crystal display panel manufactured by the conventional method. A panel is shown in which terminal connections were made without using a silane coupling agent.

According to FIG. 5, in (b) the adhesive force is reduced by almost half after 300 hours, while in (a) the adhesive force tends to increase as time passes.

In addition, as shown in Figure 6, a cycle test was repeated at low temperature (-20℃) and high temperature Toriyaya 75℃ 95% RH for 30 minutes.
Table 1 shows the results of checking for open circuits (defective connections) at the connection terminals before and after the test was carried out over a period of 0 hours.

Table 1: Comparative examples that do not use a silane coupling agent:
Although open circuits were observed in all samples, no open circuits were observed in the examples.

Example (2) In the manufacturing method of the above example, the silane coupling agent 8 is applied only to the edge of the glass substrate 2, but in this example, the silane coupling agent 8 is also applied to the base film 3 side. After that, the glass substrate 2 and the base film 3 are aligned through the anisotropic conductive film, and then heated and pressed to bond them. Note that the other conditions and manufacturing steps are almost the same as in the previous example.

Regarding the liquid crystal display panel manufactured in this manner, the adhesive strength between the glass substrate and the base film was confirmed.

Table 2 shows the liquid crystal display panel at high temperature and humidity (40°C).

95% RH) for 240 hours, and the adhesive strength was measured before and after that time. Note that the comparative example shows a liquid crystal display panel manufactured by a conventional method that does not use any silane coupling material. From the results in Table 2, it was confirmed that by applying the silane coupling agent to both sides of the glass substrate and the base substrate, the adhesive strength between the glass substrate and the base film was greatly increased.

! Table 2 Also, in joining this glass substrate 2 and base substrate 3, 4000 terminals were connected and
After exposure to 40° C., 95% RH, 240 hours), open circuit (poor connection) was confirmed.

As a result, in the example, there was no occurrence of circuit open, but in the comparative example, circuit open was observed in two to three places.

(g) Effects of the invention According to this invention, the electrode extension part of the liquid crystal display panel;
When connecting the base film on which the driving LSI element is mounted using an anisotropic conductive film, the use of a silane coupling agent increases the adhesive strength of the anisotropic conductive film and improves the reliability of the connection part. improves.

[Brief explanation of drawings]

FIG. 1 is a top view of a liquid crystal display panel showing an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, FIG. 3 is a perspective view of the main part of FIG. 1, and FIG. FIG. 3 is a sectional view of the main part, FIG. 5 is a characteristic diagram showing changes in adhesion strength and test time in a high temperature and high humidity test, and FIG. 6 is an explanatory diagram showing test conditions in which low temperature and high temperature and high humidity conditions are repeated. 1... Upper glass substrate, 2... Lower glass substrate, 3.4... Base film, 3a, 4a... Drive LSI element, 5・・・・・・
...Output terminal section, 6...Input terminal section, 7...
... Sealing agent, 8... Silane coupling agent, 9...
Anisotropic conductive film, 9a... Conductive particles, 2a...
...Transparent electrode, 3b... Electrode. value chart

Claims (1)

[Claims] 1. In a terminal connection method for a liquid crystal display element in which a driving element mounted on a flexible substrate is connected to a transparent electrode drawn out at the end of the glass substrate via a metal electrode formed on the flexible substrate, the glass substrate A step of applying a silane coupling agent to the end portion, a step of adhering an anisotropic conductive film in which conductive particles are dispersed in an adhesive to the applied portion, and aligning the end portion of the flexible substrate by overlapping the applied portion. 1. A method for connecting terminals of a liquid crystal display element, comprising the following steps: and a step of applying pressure while heating the overlapped portions.