KR20060109662A - Liquid crystal display - Google Patents

Abstract

An LCD is provided to achieve a stable connection between a bump and an electrode pad by lowering a height difference of a space in which a conductive particle is interposed and thus increasing a contact area of the conductive particle. A liquid crystal panel(10) includes an electrode pad. A driving chip(51) includes a bumper having a direct contact area protruding toward the electrode pad and electrically connected to the electrode pad, and an indirect contact area recessed with respect to the direct contact area. An area ratio of the direct contact area to the indirect contact area is 40 to 70%. The direct contact area is formed along a circumference of the direction contact area.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

1 is a plan view schematically showing the configuration of a liquid crystal display according to a first embodiment of the present invention;

2 is a cross-sectional view taken along II-II of FIG. 1;

3 is a cross-sectional view taken along line III-III of FIG. 1;

4 is a plan view of a bump according to a first embodiment of the present invention;

5 is a cross-sectional view of a driving chip for explaining a method of manufacturing a driving chip according to a first embodiment of the present invention;

6 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention;

7 is a plan view of a bump according to a second embodiment of the present invention;

8 is a cross-sectional view of a driving chip for explaining a method of manufacturing a driving chip according to a second embodiment of the present invention;

9A to 9C are diagrams for describing the third embodiment;

10A to 10C are diagrams for describing the fourth embodiment;

11A to 11B are views for explaining the fifth embodiment;

12A to 12B are views for explaining the sixth embodiment.

Explanation of Signs of Major Parts of Drawings

20: thin film transistor substrate 22: gate line

23: gate pad 24: data line

25 exposure area 30 color filter substrate

51: gate driving chip 52: bump

53: direct contact area 54: first direct contact area

55: second direct contact area 57: indirect contact area

71: flexible printed circuit board 80: anisotropic conductive film

81: resin layer 82: conductive particles

91: wafer 92: metal pad

93: protective film 94: photosensitive film

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device capable of stably connecting the driving chip and the electrode pad in mounting the driving chip of the COG method.

The liquid crystal display device includes a liquid crystal panel in which liquid crystal is injected between the thin film transistor substrate and the color filter substrate. Since the liquid crystal panel is a non-light emitting device, a backlight unit for supplying light is disposed on the rear surface of the thin film transistor substrate. The amount of light emitted from the backlight is controlled according to the arrangement of liquid crystals.

In addition to the liquid crystal display, a gate driving chip and a data driving chip for applying a driving signal to a gate line and a data line formed on a thin film transistor substrate to form a screen in a display area, a timing controller and a driving voltage generator It further includes a circuit board and the like is formed.

Among them, the gate driving chip and the data driving chip are electrically connected to the electrode pads (gate pads and data pads) formed on the liquid crystal panel, specifically, the display area of the thin film transistor substrate. The connection method includes a COG (chip on glass) in which a driving chip is directly mounted on a thin film transistor substrate, a tape carrier package (TCP) in which a driving chip is mounted on a polymer film, and a driving chip on a flexible printed circuit board. And a chip on film (COF). Among them, the COG method has a low adhesion cost and is widely used due to the advantages in that the driving chip and the liquid crystal panel are stably combined.

The conventional method for electrically connecting the driving chip and the electrode pad of the thin film transistor substrate in the COG method is as follows. First, an anisotropic conductive film is placed on the electrode pad of the thin film transistor substrate. The anisotropic conductive film is a structure in which a conductive particle is contained in a thermosetting resin layer.

Then, the bump of the driving chip is positioned to correspond to the electrode pad. At this time, the anisotropic conductive film is positioned between the electrode pad and the bump of the driving chip. Next, when the electrode pad and the bump are pressed together, the conductive particles in the anisotropic conductive film are compressed to electrically connect the bump and the electrode pad.

However, when the density of the conductive particles in the anisotropic conductive film is low, the bumps and the electrode pads may not be electrically connected, and thus there is a problem that the driving signal is not properly applied. In addition, the direct contact area is formed along the edge of the bump and protrudes toward the electrode pad to be electrically connected to the electrode pad. However, the direct contact area has a small area so that the driving signal cannot be properly applied by the contact resistance. There is this.

In addition, there is a problem that the bumps and the electrode pads cannot be stably connected to each other by the conductive particles due to the large difference in the space between the bumps and the electrode pads in which the conductive particles are interposed.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of stably connecting a driving chip and an electrode pad to each other even in the absence of conductive particles.

Another object of the present invention is to provide a liquid crystal display device which can stably connect the bump and the electrode pad to each other by increasing the contact area of the conductive particles by lowering the step height of the space in which the conductive particles are interposed.

An object of the present invention, the liquid crystal panel is provided with an electrode pad; It has a direct contact area protruding toward the electrode pad and electrically connected to the electrode pad and an indirect contact area recessed with respect to the direct contact area, and the area ratio of the direct contact area to the indirect contact area is 40 to 70%. It is achieved by a liquid crystal display device comprising a driving chip having a phosphorus bumper.

In this case, the direct contact area is preferably formed along the circumference of the indirect contact area to prevent undercut.

And, in order to stably connect the electrode pad and the bump, the width of the direct contact region is preferably 4 to 6 μm.

The direct contact region may include a first direct contact region formed along a circumference of the indirect contact region and a second direct contact region formed at the center of the indirect contact region to stably connect the electrode pad and the bump.

Here, the resin layer may be interposed between the electrode pad and the bump in order to bond and stably connect the electrode pad and the bump.

The resin layer may contain conductive particles.

According to the present invention, another object of the present invention is to provide a liquid crystal panel comprising an electrode pad having an exposed area of a predetermined shape; A driving chip having a bump protruding in the direction of the electrode pad and recessed with respect to the direct contact area and the direct contact area electrically connected to the electrode pad, and having an indirect contact area in which at least a portion does not overlap with the exposed area; And an anisotropic conductive film in which conductive particles are mixed and positioned between the electrode pad and the bump.

Here, it is preferable that the exposure area has an area ratio of 40 to 60% with respect to the total area of the electrode pad, and the indirect contact area has an area ratio of 40 to 60% with respect to the entire area of the bump.

In addition, in order to increase the contact area and lower the contact resistance, the conductive particles may be deformed by pressing to have an elliptical shape lying parallel to the plate surface of the liquid crystal panel.

Here, the exposed area and the indirect contact area may be formed on one side of the electrode pad and the bump in the shape of at least one of a triangle and a quadrangle.

In addition, the exposed area and the indirect contact area may be any one of two rectangular shapes having corners interconnected and at least two rectangular shapes arranged in a line.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a plan view schematically illustrating a configuration of a liquid crystal display according to an exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view taken along II-II of FIG. 1, and FIG. 3 is a cross-sectional view taken along III-III of FIG. 1. 4 is a plan view of the bump.

The liquid crystal display device 1 includes a liquid crystal panel 10 including a thin film transistor substrate 20 and a color filter substrate 30, and a gate driving chip 51 and data attached to an outer side of the thin film transistor substrate 20. And a flexible printed circuit board 71 and 72 connected to the driving chip 61 and the gate driving chip 51 and the data driving chip 61, respectively. In addition, the liquid crystal layer 42 may be further disposed between the thin film transistor substrate 20 and the color filter substrate 30. In some cases, a backlight unit (not shown) may be disposed on the rear surface of the thin film transistor substrate 20. It may further include.

The gate line 22 and the data line 24 are formed on the substrate material 21 of the thin film transistor substrate 20. The intersecting area becomes the display area 11 and the other areas are displayed on the screen. This area is not displayed.

Hereinafter, the configuration for driving the gate line 22 will be described, and this may be applied to the configuration for driving the data line 24.

A plurality of thin film transistors T is formed in the thin film transistor substrate 20 in the display area 11. The thin film transistor T is provided near the intersection of the gate line 22 and the data line 24. The thin film transistor T shown here is in the form of using five masks. The thin film transistor T receives a driving signal from the gate driving chip 51 through the gate pad 23 of the outer region. The gate pad 23 extends from the gate line 22 and is formed to be wider than the gate line 22. The gate insulating film 24 is removed on the gate pad 23 and is usually covered with the transparent electrode 26.

When the thin film transistor T is turned on according to the driving signal, a voltage is applied to the pixel electrode 25 connected thereto. The pixel electrode 25 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

Looking at the color filter substrate 30 as follows. The black matrix 32 and the color filter layer 33 are formed on the substrate material 31. The black matrix 32 generally distinguishes between red, green, and blue pixels, and serves to block direct light irradiation to the thin film transistor T. The black matrix 32 may be formed of a photosensitive organic material to which a black pigment is added. As the black pigment, carbon black or titanium oxide is used.

The color filter layer 33 is formed by repeating the red filter, the green filter, and the blue filter with the black matrix 32 as a boundary. The color filter layer 33 serves to impart color to light emitted from the backlight unit (not shown) and passed through the liquid crystal layer 42. The color filter layer 33 is usually made of a photosensitive organic material.

The overcoat film 34 is formed on the color filter layer 33 and the black matrix 32 which is not covered by the color filter layer 33. The overcoat film 34 serves to protect the color filter layer 33, and an acrylic epoxy material is generally used.

The common electrode layer 35 is formed on the overcoat 34. The common electrode layer 35 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The common electrode layer 35 directly applies a voltage to the liquid crystal layer 42 together with the pixel electrode layer 25 of the thin film transistor substrate 20.

In addition, polarizing plates 26 and 36 are attached to the outer surfaces of the thin film transistor substrate 20 and the color filter substrate 30, respectively. The liquid crystal 42 is formed in the space formed by the two substrates 20 and 30 and the edges of the two substrates 20 and 30 and formed of the sealant 41 which bonds the two substrates 20 and 30 to each other. The alignment state changes according to the drive signals of the drive chips 51 and 61.

The gate driving chip 51 is directly mounted on the liquid crystal panel 10 by the COG method in the outer region. Specifically, the bump 52 of the gate driving chip 51 and the gate pad 23 of the thin film transistor substrate 20 are electrically connected to each other. The gate driving chip 51 is also electrically connected to the flexible printed circuit board 71 through the gate line 22. Here, the gate line 22 connecting the flexible circuit board 71 and the gate driving chip 51 is connected by an anisotropic conductive film 80 made of conductive particles and a resin layer. The gate line 22 is divided into a portion connected to the flexible printed circuit board 71 and a portion connected to the gate pad 23 in the driving chip 51.

Hereinafter, the connection between the gate driving chip 51 and the thin film transistor substrate 20 in the liquid crystal display device having such a configuration will be described.

Conventionally, an anisotropic conductive film is interposed between the bumps and the gate pads to electrically connect the bumps and the gate pads. The anisotropic conductive film includes conductive particles, and the conductive particles serve to electrically connect the bump and the gate pad. However, when the density of the conductive particles is low, there is a problem in that the electrical connection is not made stably between some bumps and the gate pads and thus the driving signal is not properly applied. In addition, although the direct contact region 53 is formed along the edge of the bump 52 and protrudes toward the gate pad 23 to be electrically connected to the gate pad 23, the direct contact region 53 is Since the area is small, there is a problem in that the driving signal is not properly applied due to the contact resistance.

Accordingly, in the present invention, the bumps protruding toward the gate pad 23 and having the indirect contact area 57 recessed with respect to the direct contact area 53 and the direct contact area 53 electrically connected to the gate pad 23 ( 52, the driving chip 51 and the gate pad 23 can be stably electrically connected to each other even in the absence of conductive particles. Here, as shown in FIG. 4, the direct contact region 53 is formed in a band shape along the circumference of the indirect contact region 57. The direct contact region 53 has a width d1 of 4 to 6 μm, and the width d1 may be uniformly formed as a whole, or the width may be increased or decreased in a predetermined area. On the other hand, the bump may be made of gold (Au).

The area ratio of the direct contact area 53 to the indirect contact area 57 is preferably 40 to 70%. This is because if the area of the direct contact region 53 is small, the contact resistance is increased, so that the driving signal cannot be properly applied to the gate pad 23. However, when conductive particles are used, the area of the direct contact region 53 may be reduced.

As a result, the direct contact region 53 is electrically connected directly to the gate pad 23, and thus, the density of the conductive particles is low so that the direct contact region 53 is driven to the gate pad 23 even when the conductive particles are not electrically connected or there are no conductive particles. Signal can be applied.

2 and 3, a resin layer 81 exists between the gate driving chip 51 and the gate pad 23. As shown in FIG. The resin layer 81 includes a thermosetting resin and may be cured by ultraviolet rays and / or heat. Unlike the conventional one, conductive particles are not mixed in the resin layer 81. The resin pad 81 bonds and fixes the gate pad 23 and the bumps 52 having the above-described direct contact region 53 and indirect contact region 57 to each other. As shown, the direct contact region 53 is in direct contact with the gate pad 23 to be electrically connected to each other, and the indirect contact region 57 is electrically insulated. Therefore, the driving signal is applied to the gate pat 23 through the direct contact region 53.

Here, although not shown, conductive particles may be further included in the resin layer 81. As the conductive particles, plastic balls coated with metal are mainly used. By further including conductive particles, the gate pad 23 and the bump 52 are electrically connected directly by the direct contact region 53, and the gate pad 23 is formed by the conductive particles in the indirect contact region 57. And bumps 52 are electrically connected to each other, so that signals can be applied more stably.

Hereinafter, a manufacturing method of the driving chip will be described with reference to FIG. 5 is a cross-sectional view of the driving chip. After the metal pads 92 made of aluminum are formed on the wafer 91 in a predetermined pattern, the protective film 93 is entirely formed on the wafers 91 and the metal pads 92. Then, the protective film 93 on the metal pad 92 is removed to expose the metal pad 92. Here, in order to prevent undercutting, the edge of the metal pad 92 should be covered by the protective film 93. That is, the protective film 93 extends to the outer region while covering the edge of the metal pad 92.

Thereafter, the photoresist film 94 is entirely applied on the protective film 93 and the metal pad 92, and the photoresist film 94 in the region where the bumps 52 are to be formed is removed. Here, as shown in FIG. 5, in order to form the direct contact region 53 at the edge of the bump 52, a predetermined width d1 ′ is provided from the protective film 93 covering the edge of the metal pad 92. The photosensitive film 94 on the protective film is further removed. In this case, when the direct contact area 53 is to be formed wider, the width d1 ′ may be widened. That is, the area of the direct contact area 53 may be adjusted by adjusting the shape and area of the passivation layer 93.

When the bumps 52 are formed in the region between the photoresist 94, a direct contact region 53 protruding upward along the circumference of the indirect contact region 57, as in region (a), is formed and relatively recessed. An indirect contact area 57 is formed, such as area (b). The direct contact region 53 protrudes upward by the step formed by the lower passivation layer 93. Finally, the driving chip 51 is completed by removing the photosensitive film 94 around the buffer 52.

Hereinafter, a second embodiment according to the present invention will be described with reference to FIGS. 6 and 7. 6 is a cross-sectional view of a gate pad and a driving chip connection part, and FIG. 7 is a plan view of a bump of the driving chip. As shown, a first direct contact region 54 is formed at a predetermined width d3 along the circumference of the indirect contact region 57, and a predetermined width d2 is formed at the center of the indirect contact region 57. Thus, the second direct contact region 55 is formed. Forming the second direct contact region 55 in the central portion is more stable when the width of the first direct contact region 53 formed along the circumference of the indirect contact region 57 is narrower. It is for electrically connecting the bumps 52 to each other.

The sum of the areas of the first direct contact area 54 and the second direct contact area 55 formed in the bump 52 preferably has an area ratio of 40 to 70% with respect to the indirect contact area 57. The reason for such an area ratio is to apply the signal to the gate pad 23 by stably connecting the gate pad 23 and the bump 52 to each other. That is, if the area of the direct contact region 53 is small, the contact resistance is increased, and thus the driving signal is not properly applied to the gate pad 23. Here, of course, the conductive particles may further include conductive particles as in the first embodiment.

8 is a cross-sectional view of a driving chip for explaining a principle of formation of a direct contact region according to a second embodiment. Portions overlapping with the above-described first embodiment will be omitted. The protective film 92 extends outwardly and covers the edge of the metal pad 92 on the metal pad 92 formed in a predetermined pattern and has a predetermined width d2 ′ on the metal pad 92. A protective film 93 formed in a shape is formed. The photoresist 94 is coated on the passivation layer 93 and the metal pad 92, and the photoresist 94 is removed in a region where the bump 52 is to be formed. In order to form the first direct contact area 54 around the indirect contact area 57, the photosensitive film 94 is further extended from the protective film 93 covering the edge of the metal pad 92 by a predetermined width d3 ′. Remove Then, the bump 52 is applied to the region between the photoresist 94 through the same process as in the first embodiment described above, and the second direct contact of the first direct contact region 54 and (e) region of region (c) is performed. Region 55 is formed. The first direct contact region 54 and the second direct contact region 55 protrude upward from the step formed by the passivation layer 93. That is, the area and shape of the direct contact regions 54 and 55 may be adjusted by adjusting the shape of the passivation layer 93 positioned below the bump 52. In addition, a relatively indirect contact region 57 is formed between the first and second direct contact regions 54 and 55.

As a result, even when there is no conductive particle, the driving signal can be stably applied to the gate electrode and the data electrode through the direct contact region.

Hereinafter, a third embodiment, a fourth embodiment, a fifth embodiment, and a sixth embodiment according to the present invention will be described in detail with reference to FIGS. 9A through 12B.

9A to 9C are views illustrating a third embodiment according to the present invention. FIG. 9A is a plan view of a bump, and FIG. 9B is a plan view of a gate pad. A gate pad 23 having two rectangular-shaped exposed regions 25 having interconnected corners, and a direct contact region protruding toward the gate pad 23 and electrically connected to the gate pad 23. The bump 52 and the gate pad 23 and the bump, which are indented with respect to the 53 and the direct contact region 53, and are formed with an indirect contact region 57 at least partially overlapping the exposed region 25. An anisotropic conductive film 80 is interposed between the 52. The shape of the indirect contact area 57 is a shape in which the left and right sides or the top and bottom sides of the exposed area 25 are inverted. The exposed area 25 has an area ratio of 40 to 60% of the total area of the gate pad 23, and the indirect contact area 57 also has an area ratio of 40 to 60% of the total area of the bump 52. It is preferable. If the area ratio of the exposed area 25 or the indirect contact area 57 is 60% or more, the ratio of the direct contact area 53 may be reduced, so that the gate signal may not be stably applied. On the other hand, if the area ratio is 40% or less, the space in which the conductive particles 82 are interposed is small, and thus the conductive particles 82 may not be interposed.

Since the indirect contact area 57 and the exposed area 25 do not overlap, as shown in FIG. 9C, the step d ₅ of the space in which the conductive particles 82 are interposed is reduced. As a result, the conductive particles 82 are further pressed to increase the contact area between the bumps 52 and the conductive particles 82 with respect to the gate pad 23. In other words, the contact area becomes an elliptical shape lying parallel to the plate surface of the liquid crystal panel. Therefore, since the contact resistance is lowered, the gate pad 23 and the bump 52 are stably connected to each other. Here, it is preferable to use the thing with high strain rate as the conductive particle 82. In addition, since the direct contact region 53 such as 'g' exists, the gate signal may be applied more stably.

10A to 10C illustrate a fourth embodiment according to the present invention. FIG. 10A is a plan view of a bump, and FIG. 10B is a plan view of a gate pad. FIG. 10C is a cross-sectional view taken along the line VIII-V of FIG. 10A. Other than what is described below, according to the third embodiment. In the fourth embodiment, the bump 52 has an indirect contact area 53 having at least two rectangles arranged in a line, and the gate pad 23 has two rectangular exposed areas 25 having interconnected corners. Has As shown in FIG. 10C, the bumps 52 and the gate pads 23 of the conductive particles 82 are reduced because the level difference d ₆ of the space in which the conductive particles 82 are interposed is lowered to further pressurize the conductive particles 82. The contact area with respect to is increased. As a result, the contact resistance is lowered so that the bumps 52 and the gate pads 23 are stably connected to each other.

11A and 11B are plan views of bumps 52 and gate pads 23 according to the fifth embodiment, and FIGS. 12A and 12B are plan views of bumps 52 and gate pads 23 according to the sixth embodiment. It is a figure which shows. Other than what is described below, according to the third embodiment. Indirect contact regions 57 in the fifth and sixth embodiments are provided on one side of the gate pad 23 in the shape of a rectangle or a triangle, and regions in which at least a portion of the indirect contact region 57 do not overlap. Exposed area 25 is provided on one side of bump 52 in a rectangular or triangular shape, respectively. Since the indirect contact area 57 and the exposed area 25 do not overlap, as described in the third embodiment, the step difference in the space in which the conductive particles 82 are interposed is reduced. As a result, the conductive particles 82 are further pressed to increase the contact area between the bumps 52 and the gate pads 23. Therefore, since the contact resistance is lowered, the gate pad 23 and the bump 52 are stably connected to each other.

As described above, according to the present invention, a liquid crystal display device capable of stably connecting bumps of an electrode pad and a driving chip to each other can be provided.

Claims (11)

A liquid crystal panel provided with electrode pads; Protruding toward the electrode pad and having a direct contact area electrically connected to the electrode pad and an indirect contact area recessed with respect to the direct contact area, wherein an area ratio of the direct contact area to the indirect contact area is And a driving chip having a bumper of 40 to 70%. The method of claim 1, And the direct contact region is formed along a circumference of the indirect contact region. The method of claim 2, The width of the direct contact region is 4 to 6㎛ liquid crystal display device. The method of claim 1, And wherein the direct contact area includes a first direct contact area formed along a circumference of the indirect contact area and a second direct contact area formed at the center of the indirect contact area. The method of claim 1, And a resin layer interposed between the electrode pad and the bump. The method of claim 5, The resin layer comprises a conductive particle, characterized in that the liquid crystal display device. A liquid crystal panel provided with an electrode pad having an exposed area of a predetermined shape; A driving chip having a bump protruding toward the electrode pad and having a direct contact area electrically connected to the electrode pad and an indirect contact area recessed with respect to the direct contact area and at least partially overlapping the exposed area; ; And And an anisotropic conductive film in which conductive particles are mixed and positioned between the electrode pad and the bump. The method of claim 7, wherein And wherein the exposed area has an area ratio of 40 to 60% with respect to the total area of the electrode pad, and the indirect contact area has an area ratio of 40 to 60% with respect to the entire area of the bump. The method of claim 7, wherein And the conductive particles have an elliptical shape lying parallel to the plate surface of the liquid crystal panel. The method of claim 7, wherein And the exposed area and the indirect contact area are formed on at least one side of the electrode pad and the bump in a shape of at least one of a triangle and a quadrangle. The method of claim 7, wherein And the exposure area and the indirect contact area are any one of two rectangular shapes having corners interconnected and at least two rectangular shapes arranged in a line.

Images