JPH09211482A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device with which the higher fineness of a wiring pitch, the fewer man-hours for connection of members, the narrower picture framing and the lower resistance of input side wirings of an LSI chip are simultaneously embodied. SOLUTION: The input side terminals of the LSI chip 1 are connected via bumps 8 to the copper foil 9 in the lower part of a polyimide film 2 and the other front ends of the copper foil 9 are connected to a printed circuit board 10 via ACFs 7. On the other hand, the output side terminals of the LSI chip 1 are connected via the bumps 8 onto thin-film wiring materials 6 on the liquid crystal panel 4. The circumference of the bumps 8 on the input terminal side of the LSI chip 1 is sealed by a molding resin 11 in the same manner as for TCPs. A resin 12 is packed in the circumference of the output side bumps 8. The junctures are reinforced and protected by packing the resin 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting method for a display device, and more particularly to a connection between a liquid crystal panel and a liquid crystal driving element such as an LSI chip and a wiring board.

[0002]

2. Description of the Related Art In recent years, with the progress of multimedia in information equipment, liquid crystal display devices are required to have higher definition, higher quality and reliability, and smaller size. Further, in order to provide a liquid crystal display device satisfying such performance, not only improving the performance of the liquid crystal panel itself but also improving the method of mounting the liquid crystal driving element on the liquid crystal panel is an important factor.

At present, TCP (Tape Carrier Package) mounting method (see FIG. 5), COG (Chip on Glass) mounting method (see FIG. 6), etc. are mainly used as a mounting method of an LSI chip as a liquid crystal driving element. ing.

The structures of both will be described below. TC
The P mounting method is, for example, as shown in FIG. 5, a method in which a TCP 3 having an LSI chip 1 mounted on a polyimide film 2 is connected to both the liquid crystal panel 4 and the printed wiring board 10. In the TCP mounting method, the LSI chip 1
Since a copper foil is used for the wiring connected to the wiring, there is an advantage that the wiring resistance is low, the variation in the wiring resistance between the wirings is small, and a stable signal can be received. Especially,
Since a relatively large current flows in the power supply wiring on the input side, the effect of using copper having a low specific resistance of the wiring material is great. It is an essential element for improving the display quality of liquid crystal display devices.

On the other hand, in the COG mounting method, as shown in FIG. 6, the LSI chip 1 is directly connected to the liquid crystal panel 4, and the LS is mounted.
A circuit is configured by using a wiring board such as a flexible wiring board 5 on the input side of the I chip 1. In the COG mounting method, the polyimide film 2 is not used, and the difference in thermal expansion coefficient between the LSI chip 1 and the liquid crystal panel 4 is small.
As compared with the CP mounting method, the connection pitch can be made finer. In particular, at present, there is a strong demand for finer display images as described above, and therefore, they are receiving much attention.

[0006]

However, both of the mounting methods described above have the following problems, respectively.

In the TCP mounting method, the TCP 3 is connected to the liquid crystal panel 4 through an anisotropic conductive film (hereinafter referred to as ACF) 7. At this time, heat generated between the polyimide film 2 and the glass substrate 4 of the liquid crystal panel. Due to the large difference in expansion coefficient and the instability of thermal deformation of the polyimide film 2, fine pitch connection becomes difficult. Therefore, it is difficult to increase the definition of the liquid crystal display device. Further, in this method, a terminal portion for output connection is provided in the frame portion of the liquid crystal panel 4, but it is extremely difficult to make the frame width narrower than the current one in order to maintain the connection reliability.

On the other hand, in the COG mounting method, the LSI chip 1
Since it is necessary to secure a region for mounting the device in the frame portion of the liquid crystal panel, a substrate larger than the glass substrate for TCP mounting by at least the size of the LSI chip 1 is required. That is, since the number of panels that can be taken from one glass substrate is reduced, the number of panels to be taken is reduced. Further, since the frame width of the liquid crystal panel is relatively wide, it is difficult to make the module compact.

Further, since the wiring connected to the LSI chip 1 is the thin film wiring material 6 made of a high resistance material such as an ITO film, the wiring resistance varies and becomes unstable, and the quality of the displayed image deteriorates. It's easy to do. In particular, since the power supply wiring on the input side is accompanied by a large current, it becomes a big problem when designing the wiring pattern.

The present invention has been made to solve the above problems, and an object of the present invention is to miniaturize the wiring pitch in a liquid crystal display device, which has hitherto been difficult with one mounting method. Another object of the present invention is to provide a new liquid crystal display device that simultaneously realizes a narrow frame and a low resistance of the input side wiring of an LSI chip, and further reduces the number of member connection steps. That is, it is possible to improve the display quality, make the module compact, increase the throughput, and improve the reliability.

An example in which a liquid crystal driving element is mounted so as to straddle two substrates is disclosed in Japanese Patent Application Laid-Open No. 6-313893, which is made of glass.
I so that it straddles one substrate (liquid crystal panel and another substrate)
The C chip is mounted, and the two substrates are supported by the supporting member. The structure in which the IC chips are mounted on two different substrates is similar to that of the present invention. However, the object of the above publication is to inspect the output side wiring and the input side wiring individually for defects. Since the damage due to wiring defects is reduced by combining them, the original COG mounting method of mounting a driving element on a glass substrate is different from the point of view of the connection structure and wiring structure of the liquid crystal driving element. There is no change. In other words, the wiring on the input side of the IC chip is formed of a high resistance material, which still has the drawback of the above-mentioned COG mounting method that hinders power supply. Further, the two glass substrates are supported via another supporting substrate made of glass or aluminum, which causes problems such as an increase in weight of the liquid crystal panel and an increase in the number of steps.

[0012]

A liquid crystal display device of the present invention includes a liquid crystal panel in which liquid crystal is sealed between two substrates having electrodes, a liquid crystal driving element, and a wiring substrate. In the substrate, the wiring connected to the input side terminal of the liquid crystal driving element of the wiring board is formed of a low resistance metal, and the liquid crystal driving element is formed with a connection terminal with the wiring board of the liquid crystal panel. It is characterized in that it is mounted so as to straddle the surface and the wiring board, and thereby the above object is achieved.

It is desirable that the wiring board has flexibility.

Further, it is desirable that the periphery and the lower portion of the liquid crystal driving element are reinforced with resin.

The operation of the above configuration will be described below.

Since the wiring connected to the input side of the liquid crystal driving element is made of a low resistance metal such as copper, the power supply is stabilized and the quality of the displayed image is improved. Also, because only the output side terminal is directly connected to the glass substrate of the liquid crystal panel,
The wiring density in the frame portion of the liquid crystal panel is lower than that in the conventional COG and TCP mounting methods, and at the same time, the frame width of the module is narrowed. Therefore, it is effective for narrowing the frame of the module and improving the number of panels. Furthermore, since the printed circuit board or the like connected to the input-side terminals is flexible, the frame can be further narrowed.

Further, since the three members such as the liquid crystal panel 4, the LSI chip 1, the flexible wiring board 5 and the like can be connected at one time, the use amount of the ACF 7 can be reduced and the man-hours can be reduced. Cost can be reduced. Moreover, since the number of connecting steps is small, reliability is also improved.

Further, since the periphery and the lower portion of the liquid crystal driving element are reinforced by the resin, it is possible to prevent the damage due to the load and protect it from humidity.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a sectional view showing a mounting structure of an LSI chip of a liquid crystal display device according to Embodiment 1.

In FIG. 1, the input side terminal of the LSI chip 1 is connected to a copper foil 9 below the polyimide film 2 via a bump 8, and the other end of the copper foil 9 is connected to a printed wiring board 10 via an ACF 7. It is connected. On the other hand, L
The output side terminal of the SI chip 1 is connected to the thin film wiring material 6 on the liquid crystal panel 4 via the bump 8. Similar to TCP, the periphery of the bump 8 on the input terminal side of the LSI chip 1 is sealed with a mold resin 11, and the periphery and lower portion of the LSI chip 1 are filled with a resin 12.

According to the first embodiment, the number of component connecting steps can be reduced to three, and the amount of connecting members such as ACF used can be reduced, so that cost reduction and reliability improvement can be achieved. it can. Further, by adopting the above structure, the length of the connecting portion, which was conventionally 8 to 9 mm, is 5 to 6 mm.
Therefore, the frame width of the module can be reduced as compared with the conventional connection method.

Furthermore, since the LSI chip 1 is directly connected to the liquid crystal panel, the wiring pitch on the liquid crystal panel can be made finer than before, and only the output side of the LSI chip 1 is mounted on the liquid crystal panel. The frame width of the liquid crystal panel can be reduced to about 1.5 mm as compared with the conventional case. As a result, the amount of expensive glass substrate 20 used can be reduced, so that the cost can be effectively reduced. Further, for example, when a large number of panel substrates 21 are taken from one glass substrate 20, as shown in FIG. 4, a 10.4 inch diagonal panel having a terminal width of 2.5 mm is conventionally 360 mm × 460 mm, for example. Although it was possible to obtain only two sheets from the parent board of No. 3, it becomes possible to obtain four sheets as shown in FIG. 3 by reducing the terminal width, and this significantly improves the number of sheets.

Further, in the present invention, since the wiring connected to the input side of the LSI chip 1 is made of copper foil, the wiring resistance can be lowered and the input power source can be stabilized. This improves the quality of the display image. Although copper is used as the wiring material in the present embodiment, the wiring material is not limited to this, and any other low-resistance conductive material such as aluminum can be used.

Further, the resin 1 is provided around the LSI chip 1.
By filling 2 with each other, it is possible to reinforce the connection portion of each member, prevent peeling and damage of the LSI chip 1 due to a load, and further protect from humidity. In the first embodiment, the resin is used as the resin for reinforcing the LSI chip 1. However, the resin is not limited to this, and any resin adhesive or the like used in the method of mounting the liquid crystal panel can be used.

In the first embodiment, the polyimide film is used as the wiring board for connecting the input side of the LSI chip 1, but other flexible boards, printed boards, etc., which are commonly used for mounting liquid crystal display devices. Any of them can be used. Each of these substrates has the advantage of being lightweight and easy to process. Further, by bending the mounting structure on the input side, it is possible to further narrow the frame.

Further, the connection on the printed wiring board 10 and L
The ACF7 was used for both the output side connection of the SI chip 1, but the former TC is the same as the conventional TC such as solder or heat seal.
A P connection method can also be used, and the latter can use any connection method in other COG mounting methods such as silver paste and conductive particles.

As described above, according to the liquid crystal display device of Embodiment 1, the connection pitch is made finer, the resistance of the input wiring is made lower,
It is possible to improve reliability, narrow the frame, and reduce the cost at the same time.

(Embodiment 2) FIG. 2 is a sectional view showing a mounting structure of an LSI chip of a liquid crystal display device of Embodiment 2.

In FIG. 2, the input terminals of the LSI are directly connected to the copper foil on the rigid flexible printed wiring board 5 to the electrode pads 13 under the LSI chip 1 without the bumps as in the first embodiment. On the other hand, the output terminal of the LSI chip 1 is connected to the thin film wiring member 6 of the liquid crystal panel 4 as in the first embodiment. The thickness of the terminal portion of the rigid flexible printed wiring board 5 is designed to be a value larger than the height of the output side bump of the LSI chip 1 by about 1 to 3 μm, and this terminal portion is simultaneously pressed through the ACF 7 when the LSI chip 1 is pressure-bonded.
It is configured to be connected to the electrode pad 13 below the LSI chip 1. To maintain the connection reliability after crimping, LS
A resin 12 is applied around the I-chip 1 and the rigid flexible printed wiring board 5.

According to the second embodiment, since the number of connecting steps of parts is small and the amount of connecting members used can be reduced, cost reduction and reliability improvement can be achieved. In addition, by adopting the above structure, it is conventionally 8 to 9 m.
The length of the connecting portion, which was m, can be reduced to 5 to 7 mm.
That is, the frame width can be reduced as compared with the conventional connection method. Further, by making the mounting structure on the input side of the LSI chip 1 a bent type, it is possible to further reduce the frame.

Since a flexible substrate is used as the input wiring board, it can be made lighter and smaller. Further, if the height of the output side bumps can be controlled with high accuracy, the connection of the output side bumps can use any connection form of conventional COG mounting such as silver paste other than ACF7, conductive particles and the like.

Furthermore, since the LSI chip 1 is directly connected to the liquid crystal panel, the wiring pitch on the liquid crystal panel can be made finer than before, and only the output side of the LSI chip 1 is mounted on the liquid crystal panel. The frame width of the liquid crystal panel can be reduced to about 1.5 mm as compared with the conventional case. As a result, the amount of expensive glass substrate used can be reduced, so that the cost can be effectively reduced. Further, since the LSI chip 1 is reinforced by the resin, it is possible to prevent damage due to a load and to effectively protect it from humidity.

As described above, according to the liquid crystal display device of the second embodiment, it is possible to realize a fine connection pitch, a low input wiring resistance, an improved reliability, a narrow frame and a low cost at the same time. You can

[0034]

According to the present invention, since the input side wiring of the LSI chip is made of copper foil, the resistance of the input wiring can be reduced. This stabilizes the power supply and improves the quality of the displayed image. Further, since only the output side terminal is directly connected to the glass substrate of the liquid crystal panel, the wiring density of the frame portion of the liquid crystal panel becomes lower than that of the conventional COG mounting method, and at the same time the frame width becomes narrow. Therefore, it is effective for narrowing the frame of the module and improving the number of panels. Furthermore, by making the substrate such as the printed substrate connected to the input side terminal flexible, it is possible to further narrow the frame.

Further, since the three members such as the liquid crystal panel 4, the LSI chip 1, the flexible wiring board 5 and the like can be connected at one time, the usage amount of the ACF 7 can be reduced and the man-hours can be reduced. Cost can be reduced. Moreover, since the number of connecting steps is small, reliability is also improved.

As described above, it has been difficult to make the connection pitch finer, the input wiring has a lower resistance, and the reliability has been improved.
It is intended to realize a narrower frame and lower cost at the same time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mounting structure of a liquid crystal display device according to a first embodiment.

FIG. 2 is a sectional view showing a mounting structure of a liquid crystal display device according to a second embodiment.

FIG. 3 is a diagram showing an example of a substrate preparation mode of the liquid crystal display device of the present invention.

FIG. 4 is a diagram showing an example of a board preparation mode of a conventional liquid crystal display device.

FIG. 5 is a cross-sectional view showing a general configuration of a TCP mounting method in a liquid crystal display device.

FIG. 6 is a sectional view showing a general configuration of a COG mounting method in a liquid crystal display device.

[Explanation of symbols]

 1 LSI Chip 2 Polyimide Film 3 TCP 4 Liquid Crystal Panel 5 Flexible Wiring Board 6 Thin Film Wiring Material 7 ACF 8 Bumps 9 Copper Foil 10 Printed Wiring Board 11 Mold Resin 12 Resin 13 Electrode Pad 20 Glass Substrate 21 Panel Substrate

Claims (3)

[Claims] 1. A liquid crystal display device comprising a liquid crystal panel in which liquid crystal is sealed between two substrates having electrodes, a liquid crystal driving element, and a wiring substrate, wherein the liquid crystal driving element of the wiring substrate is The wiring connected to the input side terminal is formed of a low-resistance metal, and the liquid crystal driving element is arranged to straddle the wiring board and the board surface on which the connection terminal with the wiring board of the liquid crystal panel is formed. Liquid crystal display device characterized by being installed as. 2. The liquid crystal display device according to claim 1, wherein the wiring board has flexibility. 3. The liquid crystal display device according to claim 1, wherein a periphery and a lower portion of the liquid crystal driving element are reinforced with a resin.