JPH02302731A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain an upper-lower conduction structure which has low resistance and high reliability by forming a conductor of low-fusion-point alloy. CONSTITUTION:An active matrix substrate 101 and a counter substrate 103 are stuck together with a sealing agent 105 and a liquid crystal layer 106 is formed between them. A 1st electrode 102 is formed partially on the surface of the active matrix substrate 101, a 2nd electrode 104 is formed on the entire surface of the counter substrate 103, and the conductor 107 is formed between them. In this case, the conductor is formed of the low-fusion-point alloy. For example, the conductor 107 is made of In(23wt.%).Ga(57wt.%).Al(20wt.%) alloy which has 1mm<2> sectional area and is about 4mum high. The alloy enters the 1st electrode and 2nd electrode and the interface between the electrodes changes in alloy composition gradually. Consequently, the resistance of an upper-lower conduction part is reduced, the time of the writing of a signal to the counter electrode is shortened, and a faithful image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the structure of a liquid crystal display device used in a display or a light valve, and more particularly to a vertical conduction structure that increases the conductivity between opposing electrodes.

[Prior Art] The conventional technology of the vertical conduction structure will be explained by taking an active matrix type liquid crystal display device as an example. FIG. 3 is a partial schematic sectional view of a conventional liquid crystal display device. First electrode 30
The active matrix substrate 301 on which the second mold 1304 is formed and the counter substrate 303 on which the second mold 1304 is formed are coated with a sealant 30.
5, and a liquid crystal layer 306 is enclosed in the middle. The first electrode and the second electrode are electrically connected through a conductor 307, and the second electrode, which is a counter electrode, is taken out from the first electrode to an external circuit through a terminal 308. The material of the conductor is conductive paste.

Further, the second electrode is made of a transparent indium tin oxide (ITO) thin film, and the first electrode is made of a chromium (Cr) thin film.

[Problems to be Solved by the Invention] However, the above-mentioned prior art had several problems as listed below. That is, (1) the specific resistance of the conductive paste, which is a conductor, is large, and the resistance between the terminal and the second electrode is large, causing a delay in the signal transmitted to the second electrode, which causes deterioration of image quality.

(2) An oxide film is likely to be formed on the surface of the first electrode or the second electrode, and as a result, the contact resistance with the conductor increases, resulting in the deterioration of image quality as described above.

(3) Adhesion between the conductive paste used for the conductor and the first electrode or the second electrode was poor, resulting in peeling during humidity tests and other defects, resulting in poor conductivity.

etc.

Therefore, the present invention has been made to solve the problems of the prior art, and its purpose is to provide a liquid crystal display device having a low resistance and highly reliable vertical conduction structure. .

[Means for Solving the Problems] A liquid crystal display device of the present invention includes a first substrate having a first electrode, a second substrate having a second electrode opposite to the first electrode, and a second substrate having a second electrode opposite to the first electrode. a liquid crystal layer formed between the two substrates, and a liquid crystal layer formed between the first electrode and the second electrode,
A liquid crystal display device having at least a component of a conductor that connects the first electrode and the second electrode, wherein the conductor is made of a low melting point alloy; It is characterized in that it contains at least one component of indium, gallium, and aluminum, and the first electrode and the second electrode contain at least aluminum.

[Example 1] The present invention will be further described in detail according to examples.

FIG. 1 is a partial schematic sectional view of a liquid crystal display device for explaining a first embodiment of the present invention. An active matrix substrate 101 and a counter substrate 103 are laminated together with a sealant 105, and a liquid crystal layer 106 is formed between them. The first electrode 102 is formed on a part of the surface of the active matrix substrate 101, the second electrode 104 is formed on the entire surface of the counter substrate 103, and a conductor 107 is formed between them. A terminal 108 connects the first electrode to an external drive circuit. The active element is a thin film transistor (
TPT).

The first electrode 102 is made of an All film with a thickness of 0.8 μm,
The second electrode 104 is made of an Al thin film with a thickness of 0.8 μm.

The conductor 107 is made of In with a cross-sectional area of 1 mm2 and a height of about 4 μm.
(23wt, %)・Ga(5,7wt, %)-
AI (20wt, %) alloy. The alloy penetrates into the first electrode and the second electrode, and the composition of the alloy gradually changes at the interface with the electrodes.

The manufacturing procedure of the liquid crystal display device shown here will be briefly explained. First, on the first electrode of the active matrix substrate on which the sealant was formed, In(28wt0%)・Ga(72wt0%)
wt, %) alloy at 30°C in an amount of about 4 x 10-'cm3. Next, the opposing substrate is pressure-bonded with 7 lines and heated to 80° C. or higher to solidify the sealant. This heating melts Al of the first electrode and the second electrode into the conductor.

Finally, the temperature is lowered to room temperature to solidify the alloy. When a conductor is formed according to this process, the initial In-Ga
Since the alloy is liquid after 30°CR, the conventional process of applying silver paste can be applied, and even if there is an insulating alumina thin film on the A1 surface of the first or second electrode, the In-Ga alloy is A1giJI! To blend in,
Contact failure due to the presence of the insulating film can be avoided. Further, the specific resistance of the In-Ga.A1 alloy was about A1, and the resistance of the conductor including the contact resistance with the electrode was 1Ω or less.

[Embodiment 2] FIG. 2 is a partial schematic sectional view of a liquid crystal display device for explaining a second embodiment of the present invention. In this example, a transparent ITO thin film was used for the electrode of the counter substrate, and the IT
A Cr thin film is formed between the O and A1 thin films.

Since ITO and Al have very high contact resistance, Cr is sandwiched between them to reduce the contact resistance. The other structures are the same as those described in the first embodiment. That is, an active matrix substrate 201 and a counter substrate 203 are laminated together with a sealant 205, and a liquid crystal layer 206 is formed between them. First electrode 20 made of A1
2 is formed on a part of the surface of the active matrix substrate 201, a second electrode 204 made of transparent ITO is formed on the entire surface of the counter electrode 203, and a Cr layer 209 and an A1 electrode are formed on the second electrode near the first electrode. 210 are stacked, and a conductor 207 is formed between the first electrode 202 and the AI electrode 210. Terminal 20 from the first electrode to the external drive circuit
8. In this example as well, the vertical conduction resistance between the first electrode and the second electrode was 1Ω or less.

In this embodiment, an active matrix type liquid crystal display device has been described, but the present invention can also be applied to a simple matrix type liquid crystal display device. In addition, the alloy used for the conductor is In
Not only -Ga-Al alloys but also alloys containing Ga and metals other than In and AI are applicable to the present invention.

[Effects of the Invention] The liquid crystal display device of the present invention has the following special effects of the invention.

(1) Since the material of the conductor is a metal with very low specific resistance, the resistance of the conductor is low, and even if there is a natural oxide film at the interface between the electrode and the conductor, the conductor and the electrode are mutually self-contained. Erosion occurs, resulting in a perfect ohmic connection and low resistance. As a result, the resistance of the upper and lower conductive parts is reduced, the time required to write signals to the counter electrode is shortened, and a faithful image can be obtained.

(2) Since the conductor solidifies while maintaining its mechanical strength, no peeling occurs and highly reliable vertical conduction can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial schematic sectional view of a liquid crystal display device for explaining a first embodiment of the present invention. FIG. 2 is a partial schematic sectional view of a liquid crystal display device for explaining a second embodiment of the present invention. FIG. 3 is a partial schematic sectional view of a conventional liquid crystal display device. 101.201.301... Active matrix substrate 102.202.302... First electrode 103.203
．． 303... Counter substrate 104.204.304...
Second electrode 105.205.305...Sealant 106
．． 206.30G...Liquid crystal layer 107.207.307...Conductor 108.208.308...Terminal 209...Cr layer 210...A1 electrode or above Fig. 3

Claims (2)

[Claims] (1) a first substrate having a first electrode; a second substrate having a second electrode facing the first electrode; a liquid crystal layer formed between the first substrate and the second substrate; In a liquid crystal display device that includes at least a component of a conductor formed between a first electrode and the second electrode and conducting the first electrode and the second electrode, the conductor is made of a low melting point alloy. A liquid crystal display device characterized by: (2) The low melting point alloy includes at least one of indium, gallium, and aluminum, and the first electrode and the second electrode include at least aluminum. LCD display device.