JPH11337953A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve display quality and secure reliability by separating electrically interfered parts, and moreover to improve yield when a failure occurs in integrated driving circuits, by electrically connecting electric pads formed on both substrates via low-temperature fusible anisotropic conductive particles. SOLUTION: Both substrates 11, 20 are opposed to each other, for example, with a 5 μm spacing and are bonded in the periphery of the substrates with a sealant 30 made of epoxy compound resin, and this spacing is filled with liquid crystal 19. In advance to the fixing of the spacing between both substrates 11, 20 with the sealant 30, pad parts 17, 23 are electrically connected via a lower resistance. Since the sealant 30 is an insulating material, conductive particles have anisotropic conductive connection in which they are insulated in the lateral direction and the adjoining electrode pad parts 17, 23 on the same substrates 11, 20 are not brought into conduction. Thus, it is possible to make driving circuits 16, 22 normally operate and achieve an improvement in a yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device suitable for an active matrix type.

[0002]

2. Description of the Related Art An active matrix type TFT liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between an array substrate and a counter substrate having a counter electrode. The array substrate is
It comprises a plurality of intersecting scanning lines and signal lines, a thin film transistor (TFT) formed at each intersection thereof, and a pixel electrode connected to the TFT.
When the FT is sequentially driven, the voltage applied to the signal line is changed to control the potential of the pixel at the intersection of the scanning line and each signal line, change the state of the liquid crystal, and perform image output. It is.

In order to drive the pixels at present, a driving circuit for inputting a signal from outside the substrate is connected to the scanning line and the signal line end, or a driving circuit using a TFT is provided on the array substrate with the pixels and the pixels. It is customary to integrally form with the TFT in the display area.

[0004]

A drive circuit integrated type liquid crystal display device in which drive circuits are arranged on an array substrate has advantages such as reduction in size of the liquid crystal display device and cost reduction by saving steps. However, since the driving circuit of the thin film integrated circuit formed on the array substrate requires a certain area, there is a limit in reducing the size, and when a defect occurs in the driving circuit portion,
A decrease in yield is inevitable.

According to the present invention, the size of a liquid crystal display device is further reduced, the quality is improved and reliability is ensured by separating electrically interfering portions, and the yield in the case where a defect occurs in an integrated drive circuit is obtained. It is intended for improvement.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an active matrix type liquid crystal display device using TFTs and a drive circuit integrated type having a drive circuit arranged on an array substrate.
Circuits are also arranged on the opposing substrates, and the electrode pad portions formed on both substrates are electrically joined to each other via low-temperature-melting anisotropic conductive particles mixed in the sealant.

By using the circuit on the counter substrate as a part of the drive circuit, the area occupied by the drive circuit on the array substrate can be reduced, and the non-display area around the display area can be reduced. As a result, the defect occurrence rate can be reduced, the quality can be improved, and reliability can be ensured. In addition, the circuit on the counter substrate can be used as an auxiliary drive circuit for compensating for a defect of the drive circuit on the array substrate, and the drive circuit can be normally operated by connecting a new drive circuit, thereby improving the yield.

That is, the present invention provides an array in which a pixel electrode is formed in a display area, and a thin film drive circuit for driving the electrode and a first electrode pad connected to the thin film drive circuit are formed in a peripheral area thereof. A counter substrate disposed opposite the array substrate with a gap therebetween, forming a common electrode in a display area, and forming a thin film circuit and a second electrode pad connected to the thin film circuit in a peripheral area thereof; A liquid crystal display comprising a sealant for sealing the array substrate and the counter substrate in the peripheral region, and anisotropic conductive particles contained in the sealant and electrically connecting the first and second electrode pad portions. Get the device.

Further, a plurality of scanning lines and signal lines arranged on one principal surface of the substrate so as to intersect each other, thin film transistors formed at each intersection thereof, and arranged in a matrix controlled by the transistors. An array substrate having a pixel electrode and a thin film driving circuit at an end of the scanning line group and the signal line group for driving the thin film transistor; and the driving circuit disposed opposite to the array substrate. An opposing substrate having a circuit for redundantly attaching the array substrate and the opposing substrate with a gap therebetween;
A liquid crystal display device comprising: a sealing agent containing anisotropic conductive particles coated with a low-melting electric conductive material for electrically connecting the circuits of the two substrates.

The redundant circuit on the opposing substrate constitutes a part of a driving circuit, and the array substrate and the opposing substrate are sealed with anisotropic conductive particles coated with a low-temperature melting electrically conductive material. A liquid crystal display device characterized by being electrically connected by an agent.

The sealant for bonding the array substrate and the opposing substrate includes hard particles having the same diameter as the gap between the substrates and metal having a larger diameter than the gap and being soft and having a high melting temperature. Comprising anisotropic conductive particles,
A liquid crystal display device characterized by being thermosetting.

Further, the density of the anisotropic conductive particles in the sealant is 300 particles / mm ^{2 to} 600 particles / mm ^2, preferably 400 particles / mm ^{2 to} 500 particles / mm ^2. To obtain a liquid crystal display device.

In addition, the curing temperature of the sealant is lower than the melting temperature of the anisotropic conductive particles, is 150 ° C. or more, and is thermosetting bonded under a pressure of 2.0 ± 0.3 kg / cm ^2. A liquid crystal display device characterized in that the liquid crystal display device is a conductive resin.

[0014]

Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) This embodiment relates to an active matrix type liquid crystal display device. In FIGS. 1 to 4, an array substrate 11 on which pixel electrodes are arranged in a matrix is provided.
A scanning line / signal line 13 made of a metal thin film, a polysilicon thin film transistor (TFT) 14, and a pixel electrode 15 made of ITO are formed on a glass substrate 12 in the display area (A). At the scanning line end and the signal line end of the display area (B), a divided drive circuit 16 composed of a thin film circuit for inputting an electric signal for driving liquid crystal is formed integrally with the display area.

On the other hand, on the glass substrate 21 of the opposing substrate 20, there are formed a common driving electrode 25 of ITO and a remaining divided driving circuit 22 composed of a thin film circuit obtained by dividing the divided driving circuit 16.

Further, the array substrate 11 and the counter substrate 2
Reference numeral 0 denotes an electrode pad portion 17 or 23 provided in a non-display region where electrical connection between the two substrates is required, and an exposed portion which is not covered with the passivation films 18 and 24 having insulating properties. I have. The two substrates 11 and 20 are opposed to each other with a gap (cell gap) of 5 μm, and are adhered around the substrates by a sealant 30 made of an epoxy synthetic resin, and the liquid crystal 19 is held in the gap. Since the bonding is performed on the drive circuit region and the electrode pad portion around the display region, the sealing agent used for bonding is a hard 5 μm-diameter hard particle as a spacer for securing a gap. (Preferably) 31 is contained.

The electrical connection between the electrode pads 17 and 23 made of Mo or the like provided on the substrates 11 and 20 is mainly carried out by the soft low-melting conductive particles 32 further contained in the sealant. As shown in FIG. 4, the low-melting conductive particles 32 are 6 μm-diameter conductive particles in which the surface of spherical particles 33 made of a plastic ball plated with nickel is coated with a low-melting layer 34 made of a Pb—Sn alloy. Which is larger in diameter than the gap (5 μm) but mechanically flexible. Therefore, as shown in FIG. 3, after applying the sealant 30 at the time of manufacturing, the pressure is 2.0 + 0.3 kg / cm ^2.
, The crushed height becomes 5 μm. At this time, the conductive particles 32 and the pad 1 are crushed.
By increasing the contact area with 7, 23, it becomes possible to reduce the contact resistance as compared with the hard conductive particles.

Further, in order to cure the sealant 30,
Heating is performed at 200 ° C. by applying pressure, but since the melting point of the low-temperature melting layer 34 of the conductive particles is lower than the heating temperature of the sealing agent 30, the low-temperature melting layer 3 on the surface before the sealing agent 30 is cured.
4 melts.

The alloy layer 34 constituting the surface of the conductive particles
Has good wettability with respect to the metal of the electrode pad portions 17 and 23, so that the pad portions are connected to each other through the core 33 of the conductive particles at the pad portion before the substrate 11 and 20 are fixed with the sealant 30. Are electrically joined with lower resistance. Since the sealant is an insulating material, the conductive particles are insulated in the lateral direction and have an anisotropic conductive connection that does not conductively connect adjacent electrode pad portions on the same substrate.

By the above-described manufacturing method, the built-in drive circuits 16 and 22 formed in the non-display area (B) outside the display area (A) can be divided into the two substrates 11 and 20. A small liquid crystal display device can be manufactured.

(Embodiment 2) In the present embodiment, the thin film circuit on the counter substrate 20 in the first embodiment is a redundant circuit 22a. When a defective portion occurs when driven by the drive circuit of the array substrate, the defective substrate is replaced with the defective portion.
The above circuit is a new driving circuit. That is, when the drive circuit 16a on the array substrate 11 has a defect,
After cutting the outside of the electrode pad portion 17 with a YAG laser without short circuit, the wiring of the display area (A) of the array substrate is connected to the new driving circuit 22a on the counter substrate 20 side by the electrode pad portion 23, and the opposing substrate side driving circuit is connected. It is commercialized as a liquid crystal display device driven by.

However, in a portion where the two substrates 11 and 20 are not to be electrically connected (for example, there is no defect in the drive circuit 16 on the array substrate 11), a non-conductive sealant containing no conductive particles is used. I do. This makes it possible to use a substrate having a defect in a part of the drive circuit as a product. As described above, even when the drive circuit of the array substrate is locally defective and another drive circuit portion can be used, the redundant circuit of the counter substrate can be effectively used.

Further, the redundant circuit 22a on the opposite substrate is
It may be used as a circuit for G (test element group).

It should be noted that the anisotropic conductive particles described in the above embodiment include those in which a metal powder having a higher melting temperature is mixed into a soft synthetic resin sphere.

[0026]

According to the present invention, in a drive circuit-integrated liquid crystal display device, a low resistance connection between the array substrate and a circuit in the opposing substrate is made by using low-temperature melting conductive particles, so that the drive circuit outside the display region is provided. Can be achieved by reducing the overall size of the device in which the substrate is divided and formed on both substrates, improving the yield by incorporating a redundant drive circuit into the opposing substrate and selectively using a drive circuit having no defect.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing the configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view according to the embodiment of the present invention.

FIG. 3 is a partially enlarged sectional view of FIG. 2;

FIG. 4 is a cross-sectional view of a conductive particle used in the embodiment of the present invention.

[Explanation of symbols]

 (A): display area (B): non-display area 11: array substrate 12: glass substrate 13: scanning line / signal line 14: thin film transistor 15: pixel electrode 16, 22: drive circuit 17, 23: electrode pad section 18, 24: passivation film 19: liquid crystal 20: counter substrate 21: glass substrate 25: counter electrode 30: sealant 31: hard particles 32: low-temperature melting conductive particles 33: spherical particles 34: low-temperature melting layer

Claims (6)

[Claims] An array substrate having a pixel electrode formed in a display area, a thin-film drive circuit for driving the pixel electrode in a peripheral area thereof, and a first electrode pad connected to the thin-film drive circuit; An opposing substrate disposed opposite to the array substrate with a gap therebetween, forming a common electrode in a display region, and forming a thin film circuit and a second electrode pad portion connected to the thin film circuit in a peripheral region thereof; A liquid crystal display device comprising: a sealant for sealing the counter substrate in the peripheral region; and anisotropic conductive particles contained in the sealant and electrically connecting the first and second electrode pad portions. 2. A plurality of scanning lines and signal lines arranged on one principal surface of a substrate so as to intersect each other, thin film transistors formed at each intersection thereof, and arranged in a matrix controlled by the transistors. An array substrate having a pixel electrode and a thin film driving circuit at an end of the scanning line group and the signal line group for driving the thin film transistor; and the driving circuit arranged opposite to the array substrate. A counter substrate having a redundant circuit, an array substrate and the counter substrate are bonded to each other with a gap therebetween, and anisotropically coated with a low-melting electric conductive material for electrically connecting the circuits of the two substrates. A liquid crystal display device comprising: a sealant containing conductive particles. 3. A sealant comprising anisotropic conductive particles, wherein the redundant circuit on the opposing substrate forms a part of a driving circuit, and the array substrate and the opposing substrate are coated with a low-temperature-melting electric conductive material. 3. The electrical connection according to claim 2,
The liquid crystal display device as described in the above. 4. The sealant for bonding the array substrate and the counter substrate includes hard particles having the same diameter as a gap between the substrates, and soft anisotropic conductive particles having a diameter larger than the gap. 3. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is thermosetting. 5. The liquid crystal display device according to claim 2, wherein the density of the anisotropic conductive particles in the sealant is 300 / mm ^{2 to} 600 / mm ² . 6. The sealant has a curing temperature lower than a melting temperature of the anisotropic conductive particles and 150 ° C. or higher,
3. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is a thermosetting resin bonded under a pressure of 2.0 ± 0.3 kg / cm ² .