Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-10-27
2003-12-30
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S149000
Reexamination Certificate
active
06671024
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a connecting structure for electroconductive connection of two adherends by an anisotropic conductive adhesive agent. Particularly, the present invention relates to an anisotropic conductive adhesive agent and the manufacturing method thereof, this anisotropic conductive adhesive agent is used particularly for connecting fine-pitched terminals, for example, in case of electrically connecting input terminals of liquid crystal panels (liquid crystal displays) to outer leads in TAB (Tape Automated Bonding); and also relates to a liquid crystal display device and electronic equipment using them.
Further, the present invention relates to an anisotropic conductive adhesive agent and the manufacturing method thereof, the anisotoropic conductive adhesive agent is used for conductive connection between liquid crystal panels and circuit boards, a typical example of which is TAB substrates.
BACKGROUND ART
As shown in
FIG. 11
(A), an anisotropic conductive adhesive agent
50
is used for connecting between fine-pitched terminals, such as connecting input terminals
12
provided on a glass substrate
11
constituting a liquid crystal panel to TAB
13
terminals (bumps)
14
.
The conventional anisotropic conductive adhesive agents
50
have been comprised of a thermosetting or thermoplastic insulating adhesive agent
51
such as epoxy resin or the like, and a plurality of conductive particles
52
provided in this adhesive agent, wherein the conductive particles
52
is uniformly positioned within this adhesive agent.
Then as shown in
FIG. 11
(B), the TAB
13
is thermo compression bonded and the terminal
14
is pressed into the anisotropic conductive adhesive agent
50
, thus continuity between the terminals
12
and
14
is realized by means of providing the conductive particles
52
therebetween.
Also, there are cases in which the IC is not mounted on the TAB, but directly mounted upon the glass substrate and a flexible substrate is connected to the input terminals of the IC through the wirings on the glass substrate. In such case, as well, the anisotropic conductive adhesive agent is used for connecting the wiring on the glass substrate and the flexible substrate.
It is preferable to include three to ten or more conductive particles
52
between the each of terminals
12
and
14
, in order to secure the conductivity.
However, the conventional anisotropic conductive adhesive agent
50
has a problem that as shown in
FIG. 11
(B), when the terminal
14
is pressed into the insulating adhesive agent
51
, the insulating adhesive agent
51
provided at the portion of the terminal
14
flows toward to the terminal
14
, and the conductive particles
52
of the aforementioned adhesive agent
51
are also flowed together, as a result, the number of conductive particles
52
remaining between the terminals
12
and
14
is reduced and conductive reliability diminishes.
Also, there is the need to include a great number of conductive particles in the insulating adhesive agent in order to make the number of conductive particles remaining between the terminals
12
and
14
enough, and this has been a problem in that the cost of materials for manufacturing the anisotropic conductive adhesive agent is expensive.
It is an object of the present invention to provide an anisotropic conductive adhesive agent which is capable of making a predetermined number of conductive particles being included certainly between the terminals to be connected so as to improve conductive reliability, a manufacturing method for easily manufacturing the anisotropic conductive adhesive agent, and a liquid crystal display device and an electronic equipment containing the anisotropic conductive adhesive agent utilized therein.
SUMMARY OF THE INVENTION
The connecting structure according to the present invention is a connecting structure for electrically connecting two adherends consisting of at least a first adherend on which a plurality of terminals are formed and a second adherend including terminals which are thicker than the terminals formed on the first adherend, the adherends being positioned so as to face one another with the terminals facing inwards across the anisotropic conductive adhesive agent; wherein the anisotropic conductive adhesive agent includes: an insulating adhesive agent; and a plurality of conductive particles distributed on one side of the first adherend.
According to the connecting structure of the present invention, the conductive particles are distributed on one side of the first adherend. Accordingly, an inexpensive connecting structure by which the number of conductive particles included in the anisotropic conductive adhesive agent is reduced can be realized, and a sufficient number of conductive particles can be secured at the electrical connection portion, so the number of defective articles is drastically reduced. Also, regarding the case of performing compression bonding of the first adherend and the second adherend, the conductive particles are not included in the anisotropic conductive adhesive agent which flows out by being pressed out by the terminals provided on the side to which the conductive particles are not unevenly distributed, i.e., by the thicker terminals. Accordingly, the number of conductive particles remaining between the terminals to be connected is not reduced and the connection can be made in a sure manner, and further, the number of conductive particles is made to be uniform at each connected portion, which is extremely desirable from a manufacturing control perspective.
The liquid crystal device according to the present invention is a liquid crystal device comprised of a pair of substrates between which liquid crystal is sealed, and a plurality of terminals formed at least on one of the substrates; and a circuit substrate, which contains a plurality of terminals formed thereon and is electrically connected with said liquid crystal panel by anisotropic conductive adhesive agent, wherein the anisotropic conductive adhesive agent includes: an insulating adhesive agent; and a plurality of conductive particles distributed on one side of a substrate, which is a side being equipped with a terminal, which is the thinner one of the terminals formed on the one substrate and terminals formed on the circuit substrate.
According to the liquid crystal device of the present invention, the conductive particles are unevenly distributed on the thinner side, i.e., to the side of the substrate which has terminals with smaller dimensions of protrusion toward the anisotropic conductive adhesive agent. Accordingly, the number of conductive particles included in the anisotropic conductive adhesive agent can be reduced and thus an inexpensive connecting structure can be realized, and a sufficient number of conductive particles can be secured at the electrical connection portion, so the number of defective articles is drastically reduced. Also, regarding the case of performing compression bonding of the liquid crystal panel substrate and the circuit substrate, the conductive particles are not included in the anisotropic conductive adhesive agent which flows out by being pressed out by the terminals formed on the side, to which conductive particles are not unevenly distributed, i.e., by the thicker terminals. Accordingly, the number of conductive particles remaining between the terminals to be connected is not reduced, and further, the number of conductive particles is uniform at each connected portion, which is extremely desirable from a manufacturing control perspective.
Generally, transparent electrodes such as typified by ITO are formed on the liquid crystal panel substrates, and metal terminals are formed on the circuit substrates such as the TAB substrate. There are many cases that the transparent electrodes such as ITO are thinner compared to the metal terminals, so it is preferable to unevenly distribute the conductive particles to the side of the liquid crystal panel substrate.
The liquid crystal device according to the present invent
Harness & Dickey & Pierce P.L.C.
Nguyen Dung
Seiko Epson Corporation
Ton Toan
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