JPH07152044A - Display device - Google Patents

Abstract

PURPOSE:To reduce the size and production cost of a display device. CONSTITUTION:A circuit board 28 consisting of multilayered wirings is connected to a substrate 23 disposing an IC for driving on it in such a manner that the end faces come into contact with each other. Input wirings for the IC 27 for driving are formed on this circuit board 28. These input wirings and the IC 27 for driving are connected by wire bonding 30. The circuit board consisting of the multilayered wirings is otherwise connected to the one substrate in such a manner that the end faces come into contact with each other. The IC for driving is disposed on this circuit board and drawing-out electrodes from the display region are formed in the non-display region of the one substrate. These drawing-out electrodes and the IC for driving are connected by wire bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a display device in which a display portion such as liquid crystal, plasma, EL and the like and an IC for driving the display portion are integrated.

[0002]

2. Description of the Related Art Various methods have been proposed as means for providing a driving IC in a display device. One example of such methods is bare chip mounting of an IC. And the IC are connected by wire bonding.

For example, in the field of liquid crystal display devices,
A COG type liquid crystal display device has been proposed. According to this liquid crystal display device, two glass substrates having electrodes on the inner surface are bonded together via a liquid crystal layer, and the periphery of the liquid crystal layer is sealed by a sealing material. The liquid crystal display cell configuration is stopped, and a driving IC is provided on one of the glass substrates,
The wiring terminal extending from the liquid crystal display cell and the driving IC are connected by wire bonding, and the driving IC is also connected to the flexible wiring board for the external connection terminal portion.

In addition, in the liquid crystal display device having this structure, the connection wiring on the glass substrate is formed of a metal such as aluminum by a thin film process.
It was practically difficult to make this film thickness several μm or more. In particular, when connecting two glass substrates having electrodes on the inner surface through the liquid crystal layer, this connecting wire has a thickness of 1 μm in order to make the distance between the substrates strict.
I had to set it around m.

However, in the actual COG type liquid crystal display device, when the thickness of the connection wiring is set to about 1 μm, the resistance value of the wiring becomes large and the input signal between the electrodes is deteriorated. In order to solve the problem, the width of the connection wiring has been increased.

However, due to the width of the connection wiring and the area required for routing it, the occupied area becomes large, and the size of the device itself becomes large accordingly, and in recent years there is a tendency for downsizing of the device. Among them, there was a problem that it did not meet the demand.

Further, although the connection wiring is formed of a metal material such as aluminum, it is practically difficult to mount the electronic component chip on the connection wiring made of aluminum through solder, and therefore, for example, a connector is required as required. However, there is a problem that capacitors, resistors, etc. cannot be directly mounted on the connection wiring.

On the other hand, in such a COG type liquid crystal display device, it has been proposed to attach a flexible circuit board (FPC) having a bus line which is a connection wiring to a glass substrate (Japanese Patent Laid-Open No. 64-37533). No.).

FIG. 10 is a plan view of a main part of the proposed liquid crystal display device 1. According to FIG. 10, an upper glass substrate 2 and a lower glass substrate 3 having transparent electrodes (not shown) formed on their opposing surfaces are shown. A liquid crystal is sealed in between by a sealant, and a connection pattern 4 connected to each transparent electrode of the upper glass substrate 2 and the lower glass substrate 3 is formed on the protruding portion 3a of the lower glass substrate 3. ing. Reference numeral 5 is a flip-chip type driver (driving) IC with solder bumps, and 6 is an FPC in which a bus line 7 is formed. Further, a relay connection pattern 8 to the bus line 7 is formed on the projecting portion 3a by a solderable metal. The FPC 6 is provided with a plurality of terminal portions 6a corresponding to the driver ICs 5 formed by forming the relay connection pattern 10 connected to the through hole 9. The relay connection pattern 10 of the terminal portion 6a and the relay connection pattern 8 and 8 are electrically connected to each other by soldering or through an anisotropic conductive film. The FPC 6 is bent at a position A indicated by a chain double-dashed line in the drawing to be located on the back surface side of the lower glass substrate 3 so as to save space.

However, the liquid crystal display device 1 having this structure
In this case, since the solder bumps are used for fixing and electrically connecting the driver IC 5, the relay connection pattern 8 has to be further formed, whereby the extra drawing leads to an increase in the size of the liquid crystal display device 1. There was a problem.

Moreover, the line width of each of the relay connection patterns 8 and 10 for electrically conducting the soldering or through the anisotropic conductive film needs to be at least about 3 mm, which also results in a large routing pattern. Therefore, there is a problem that the size of the liquid crystal display device 1 becomes large.

In addition, the long FPC 6 is attached to the lower glass substrate 3
When it is arranged along the overhanging portion 3a, it is practically difficult to electrically conduct with high precision due to the flexibility of the FPC 6 itself, and there is a problem that mass productivity is difficult.

Further, the bending position of the FPC 6 is near the edge of the lower glass substrate 3, and the FPC 6 is forcibly bent in the vicinity thereof. As a result, stress is generated in the FPC 6 and the reliability of the FPC 6 itself is significantly lowered. There is also the problem of doing.

Furthermore, in this FPC 6, the bus line 7 is actually provided on one surface, and the relay connection pattern 10 is formed on the other surface via the through hole 9. 2 bus lines
It is practically difficult to form a multi-layered structure including more than one layer due to its own bent structure.

Further, instead of the liquid crystal display device 1 provided with the FPC, there has been proposed a structure in which a so-called TAB in which a driving IC is mounted on a tape carrier is provided on a glass substrate. FIG. 11 is a cross-sectional view of a main part of the TAB type liquid crystal display device 11, in which a liquid crystal is interposed between an upper glass substrate 12 and a lower glass substrate 13 each having a transparent electrode (not shown) formed on the surfaces facing each other with a sealing material interposed therebetween. (Not shown) is enclosed, and the upper glass substrate 12 is provided on the protruding portion 13 a of the lower glass substrate 13.
And a connection pattern (not shown) connected to each transparent electrode of the lower glass substrate 13. 14 is a driving IC
Reference numeral 15 is a TAB mounted on a film carrier 16, and the driving IC 15 is fixed via a solder bump 17 to be electrically conductive, and the IC 15 is covered with a protective resin 18. In addition, the circuit board (PCB) 19 provided with the bus line is attached to the protruding portion 1 of the lower glass substrate 13.
3a are arranged side by side on the end face, and the circuit board 19 and the overhanging portion 13a
The TAB 14 is fixed on and and electrically connected. For such fixing and conduction, the solder 20 is used in the circuit board 19, and the anisotropic conductive film 21 is used in the overhanging portion 13a.

However, according to the liquid crystal display device 11 of the TAB system, the TAB 14 must be joined to two kinds of members, that is, the circuit board 19 and the overhanging portion 13a, and different connection methods must be adopted. No, this increases the number of processes and the number of parts, and as a result,
There is a problem that the manufacturing cost increases.

In addition, the problem that the number of processes is increased, the number of parts is increased, and the manufacturing cost is increased is described in Japanese Patent Publication No.
The same can be pointed out in the liquid crystal panel described in No. 23612.

[0018]

According to a first aspect of the present invention, there is provided a display device in which a driving IC is disposed in a non-display area on a substrate having a display area, and the end face of the substrate and multilayer wiring are provided. The circuit board is arranged so that the end faces of the circuit board come into contact with each other, and the input wiring for the driving IC is formed on the circuit board, and the input wiring and the driving IC are connected by wire bonding. To do.

According to the second aspect of the present invention, the display device is arranged so that the end face of the substrate having the display area and the end face of the circuit board composed of the multilayer wiring contact each other, and the driving IC is arranged on the circuit board. At the same time, a lead-out electrode from the display area is formed in the non-display area of the substrate, and the lead-out electrode and the driving IC are connected by wire bonding.

[0020]

According to the display device of the present invention, a circuit board composed of multi-layered wiring is provided in parallel so that the end surfaces of the drive IC mounting board come into contact with each other, and the circuit board for the drive IC is mounted on the circuit board. Input wiring is formed, and the input wiring and the driving IC
And is connected by wire bonding,
Further, according to the display device of claim 2, a circuit board composed of multi-layered wirings is arranged in parallel so that the end faces of the board come into contact with each other, and the driving IC is arranged on the circuit board, and one of the boards is provided. In this configuration, a lead electrode from the display area is formed in the non-display area, and the lead electrode and the driving IC are connected by wire bonding.

In the case of the two circuit boards thus arranged, the bus lines required for the driving IC are formed on this board, and the power source, the processing circuit and the like are further mounted, and various wirings are formed in multiple layers. This allows the width of these connecting wires to be increased while limiting the dimensions of the circuit board, and as a result, the overall width of the connecting wires and the area required for routing them can be increased. The size of the liquid crystal display device can be reduced with the reduction in size.

If necessary, for example, a connector, a capacitor, a resistor, etc. can be directly mounted on the connection wiring on the circuit board.

In addition, as compared with the conventional liquid crystal display device provided with an FPC, the FPC is not used, and the circuit boards are arranged side by side so that the end faces of the substrates in the display area contact each other. The problem due to bending, that is, the electrical precision is eliminated, and thus a highly reliable and high-quality display device can be mass-produced.

Moreover, compared to the conventional liquid crystal display device provided with the TAB, there is a problem caused by mounting the TAB, that is, two kinds of members are connected to the TAB by different connection methods, and the number of steps is increased. However, the problem that the number of parts is increased is solved, and as a result, the manufacturing cost is reduced.

[0025]

EXAMPLE This example will be described below by taking a liquid crystal display device as an example.

(Example 1) FIGS. 1 to 3 show the CO according to claim 1.
FIG. 1 shows a G type liquid crystal display device 22. FIG. 1 is a sectional view of a main part of the device 22, FIG. 2 is an exploded view, and FIG. 3 is a perspective view.

According to these figures, 23 is a segment side glass substrate, and 24 is a common side glass substrate having a smaller area than the glass substrate 23.
A liquid crystal is filled between 24 by a sealant 25 to form a display area 26. A drive IC 27 is mounted in the non-display area of the glass substrate 23, and a glass epoxy substrate 28 (CEL-445A manufactured by Shin-Kobe Electric Co., Ltd.), which is a circuit board, is arranged in parallel so that the end faces of the substrate 23 come into contact with each other. To do. This substrate 28 has a multi-layer wiring structure in which one or more wiring layers can be formed inside the substrate. When the glass epoxy substrates 28 having such a multi-layer wiring structure are arranged in parallel, the glass substrate 23 and the glass epoxy substrate 28 are arranged. It is preferable that the thickness of each plate is substantially the same in order to maintain the fixing strength between the plates.

As the fixing means for this juxtaposition, there is a method of simply adhering and fixing the abutting surface with an adhesive, but in addition to this, as will be described later, a small piece is separately attached in the vicinity of the abutting and the reinforcing means is used. You may fix it. 29 is the glass substrate 2
3 is a connection wiring of electrodes arranged on the inner surfaces of 3 and 24.

It is desirable that the glass substrate 23 and the glass epoxy substrate 28 have substantially the same coefficient of thermal expansion. When a normal plate glass is used for the glass substrate 23, the coefficient of thermal expansion thereof is 8 to 9 × 10 ⁻⁶ / ° C., whereas the coefficient of thermal expansion of the glass epoxy substrate 28 is also 8 to 9 × 10 ^−6.
/ ° C. However, the coefficient of thermal expansion is 10-15 × 10 ^-6 /
Even if another type of glass epoxy substrate 28 having a temperature of 0 ° C. was used, there was no practical problem. There are two types of the driving IC 27, that is, an IC 27a in the X direction and an IC 27b in the Y direction of the display area 26.
There are 8a and 28b. The glass epoxy board 28a is a circuit board on the signal side, and is a multi-layer board in which bus lines necessary for driving the IC 27a and each system such as a power supply and a logic are wired in layers, and each IC 27a is arranged on this board. Pads for wire bonding are arranged. Further, the glass epoxy board 28b is a circuit board on the scanning side, is a multi-layer board on which a bus line necessary for driving the IC 27b, and various external power supply and signal processing circuits are mounted. Pads for wire bonding with each IC 27b are arranged. Further, terminals are provided near the glass epoxy board 28b of these two glass epoxy boards 28a, and the terminals are connected to the glass epoxy board 28b. Then, the adjacent ends of the two substrates 27 and 28 are electrically connected by a jumper (small FPC piece) not shown.

Further, glass epoxy substrates 28a and 28b
The bus lines on the top of the IC are wire-bonded 30 to the ICs 27a and 27b, respectively.
a and 27b are wire bonding 3 together with the connection wiring 29
It has been 1. These wire bonds 30, 31
Is performed with a gold wire, and the corresponding bonding pad is surface-treated with gold, aluminum, or the like.

Thus, in the liquid crystal display device 22 of this example, the bus line required for the driving IC 27 is formed on the glass epoxy substrate 28, and each system such as the power supply and the logic is further wired in layers. Alternatively, the glass epoxy board 28 is provided with a multi-layer board on which various power supplies and signal processing circuits supplied from the outside are mounted. This allows the glass epoxy board 28 to be reduced in size and the width of the connection wiring on the board 28. As a result, the size of the liquid crystal display device 22 can be reduced along with the overall reduction in the width of the connection wiring and the area required for the wiring. For example, it was experimentally confirmed that the size was reduced by about 20 mm in the X direction as compared with a conventional COG type liquid crystal display device.

In addition, as compared with the conventional liquid crystal display device provided with an FPC, the FPC is not used. Therefore, the problem due to bending of the FPC, that is, the electrical precision defect can be solved.

Moreover, since the number of parts is reduced as compared with the conventional liquid crystal display device provided with the TAB, the number of steps is also reduced, and as a result, the manufacturing cost is reduced.

Further, the driving IC 2 is mounted on the glass substrate 23.
7 is mounted, the surface smoothness of the substrate 23 enables highly reliable wire bonding 31. Furthermore, since the connection wiring 29 does not extend to the end of the glass substrate 23, there is an advantage that there is no influence due to cracks or breaks at the edge of the glass plate.

(Example 2) In the liquid crystal display device 32 according to claim 2 of the present example, as shown in FIG. 4, the mounting portion of the driving IC 27 of the liquid crystal display device 22 is replaced with the glass substrate 23 and glass epoxy. The substrate 28 is used, and other configurations are the same. In the figure, members having the same functions as those shown in FIGS. 1 to 3 are designated by the same reference numerals.

Also in the liquid crystal display device 32 of this example, the glass epoxy substrate 28 of the multi-layer substrate can be used to reduce the size of the substrate 28, and the width of the connection wiring on the substrate 28 can be increased. Was achieved.

(Example 3) In this example, as shown in FIGS. 5 to 9, in the liquid crystal display device 22 in which the driving IC 27 is mounted on the glass substrate 23, the glass epoxy substrate 28 is arranged side by side on the glass substrate 23. As the fixing means, the liquid crystal display device 33 is obtained by separately using, for example, a small piece of carbon steel SS41 or S35C or a glass epoxy plate, and fixing by this reinforcing means. 5 is a plan view of the liquid crystal display device 33, FIG. 6 is a front view thereof, FIG. 7 and FIG. 8 are cross-sectional views of main parts of the liquid crystal display device 33, and FIG. 9 is a main part of the liquid crystal display device 33. It is a perspective view. In the figure, the same parts as those shown in FIGS. 1 to 3 are designated by the same reference numerals.

FIG. 7 shows a structure in which a lower reinforcing plate 35 (for example, a glass epoxy plate) is attached via an adhesive layer 34 such as a double-sided tape to fix the glass epoxy substrate 28a.

The lower reinforcing plate 35 is a strip plate, and the size of the short side is such that the glass epoxy substrate 28a is fixed to the glass substrate 23 and does not reach the display area of the substrate 23. To decide. Further, the longitudinal dimension may be about the entire length of the glass epoxy substrate 28a. The thickness of the plate 35 may be 1 mm at the maximum, for example 0.3 mm.

8 and 9 show a structure in which the upper reinforcing plate 37 is attached, and the glass substrate 23 and the upper reinforcing plate 37 are fixed via an adhesive layer 36 such as a thermosetting adhesive, and The glass epoxy substrate 28b is fixed to the reinforcing plate 37 via an adhesive layer 36 such as solder. By this soldering, the glass epoxy board 28b can be easily removed and the board 28b can be reused.

When the glass epoxy substrate 28 is fixed by the reinforcing plates 35 and 37 as described above, the structure shown in FIGS. 5 and 6 is obtained. In FIG. 5, the jumper (small FPC piece that electrically connects the adjacent ends of the boards 27 and 28 to each other) is illustrated by the reference numeral 38, and 39 indicates a connector.

For the lower reinforcing plate 35, the driving IC 27
In order to protect the wire bondings 30 and 31 of the IC 27a because the width of the non-display area serving as the array surface of a is relatively narrow (for example, 5 mm or less), this IC
Although 27a is sealed with resin, a lower reinforcing plate 35 is attached to the back side of the glass substrate 23 in order to avoid the influence of this sealing step.

As for the upper reinforcing plate 37, the drive I
Since the width of the non-display area serving as the array surface of C27b is relatively large (for example, 10 mm or more), the upper reinforcing plate 37 is attached to the upper side of the glass substrate 23 so as not to be affected by the insertion / removal of the connector 39 or the like. . Such an upper reinforcing plate 37 may be formed of a highly rigid metal or heat resistant resin.

Thus, in the liquid crystal display device 33 of this example, each reinforcing plate 3 is different from the liquid crystal display device 22 of (Example 1).
It was firmly fixed with Nos. 5 and 37, which provided high reliability over a long period of time.

Further, although the present inventor adopted a glass epoxy substrate as a circuit board as an example, in addition to this, a circuit such as a BT resin substrate, an aramid fiber reinforced epoxy substrate, a substrate in which FPC is reinforced from the backside with glass epoxy, a ceramic substrate, It was confirmed experimentally that the same effect was obtained even when the glass substrate 23 was similarly provided side by side with the substrate.

The present invention is not limited to the liquid crystal display device as in the above embodiment, but can be applied to various display devices such as plasma and EL. Other than this embodiment, various modifications and improvements may be made without departing from the scope of the present invention.

For example, in this embodiment, two glass epoxy substrates 28a and one glass epoxy substrate 2 are used.
8b, but in addition, if necessary, one glass epoxy substrate 28a and one glass epoxy substrate 28
b, or may be integrated by one glass epoxy substrate 28.

Furthermore, the mounting surface of the driving IC 27 on the glass substrate 23 or the glass epoxy substrate 28 may be the back surface on the side shown in the above embodiment.

Further, the fixing means for the glass substrate 23 and the glass epoxy substrate 28 is not limited to the above-mentioned example, but may be arranged in parallel by any desired method.

[0050]

As described above, according to the display device of the first aspect, a circuit board composed of multi-layered wiring is continuously provided on the circuit board so that the end surfaces of the drive IC mounting board come into contact with each other. The input wiring for the driving IC is formed on the substrate, and the input wiring and the driving IC are connected by wire bonding. Further, according to the display device of the second aspect, a circuit board composed of multi-layered wiring is provided in series so that the end surfaces of the board come into contact with each other, a driving IC is arranged on the circuit board, and In this structure, a lead electrode from the display area is formed in the display area, and the lead electrode and the driving IC are connected by wire bonding.

According to both of the inventions, the width of the connection wiring can be increased while limiting the size of the circuit board. As a result, the overall width of the connection wiring and the area required for routing the connection wiring can be reduced. The miniaturization of the liquid crystal display device has been achieved along with the miniaturization. If necessary, for example, a connector, a capacitor, a resistor, etc. could be directly mounted on the connection wiring on the circuit board.

Further, according to the present invention, it is possible to mass-produce a display device having high reliability and high quality and reduce the manufacturing cost, as compared with the conventional display device provided with the FPC or the display device provided with the TAB. did.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a liquid crystal display device according to an example.

FIG. 2 is an exploded view of the liquid crystal display device of the embodiment.

FIG. 3 is a perspective view of a liquid crystal display device of an example.

FIG. 4 is a cross-sectional view of essential parts of a liquid crystal display device of another embodiment.

FIG. 5 is a plan view of a liquid crystal display device according to still another embodiment.

FIG. 6 is a front view of a liquid crystal display device of still another embodiment.

FIG. 7 is a cross-sectional view of a main part of a liquid crystal display device of still another embodiment.

FIG. 8 is a cross-sectional view of a main part of a liquid crystal display device of still another embodiment.

FIG. 9 is a perspective view of a main part of a liquid crystal display device according to still another embodiment.

FIG. 10 is a plan view of a main part of a conventional liquid crystal display device.

FIG. 11 is a cross-sectional view of a main part of a conventional liquid crystal display device.

[Explanation of sign]

 23 Glass Substrate 26 Display Area 27 Driving IC 28 Glass Epoxy Substrate 29 Connection Wiring 30, 31 Wire Bonding 35 Lower Reinforcing Plate 37 Upper Reinforcing Plate

Claims (2)

[Claims] 1. A driving IC is arranged in a non-display area on a substrate having a display area, and the driving IC is continuously arranged so that an end surface of the board and an end surface of a circuit board composed of multi-layer wiring contact each other. A display device in which an input wiring for the driving IC is formed on the input wiring, and the input wiring and the driving IC are connected by wire bonding. 2. An end face of a substrate having a display region and an end face of a circuit board composed of multi-layered wiring are arranged so as to contact each other,
A display device in which a driving IC is arranged on the circuit board, an extraction electrode from the display area is formed in a non-display area of the board, and the extraction electrode and the driving IC are connected by wire bonding.