KR20050083020A - Liquid crystal display device - Google Patents

Abstract

Damage to or disconnection of the circuit pattern of the flexible circuit board caused by the stress when bending the flexible circuit board is prevented. A junction portion including an output lead terminal string 42 electrically connected to a connection terminal string 11 of the TFT array substrate 1 at a portion overlapping the TFT array substrate 1 of the TCP 4; (7) had to be covered. In the portion where the TFT array substrate 1 and the solder resist 7 overlap, the rigidity (strength) of the bent portion of the TCP 4 including the portion in contact with the edge portion 1a of the TFT array substrate 1 is increased. The circuit pattern 6 is hardly buckled. In addition, since the edge 1a of the TFT array substrate 1 does not directly contact the circuit pattern 6 of the TCP 4, the TCP 4 is not damaged without damaging the substrate edge 1a. Damage and disconnection of the circuit pattern 6 of the TCP 4 caused by the stress at the time of bending can be prevented.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, a liquid crystal display in which a flexible circuit board on which a driving LSI of a liquid crystal display panel is mounted is mounted on a connection terminal string formed on the outer periphery of a transparent insulating substrate provided with a display pixel electrode through an anisotropic conductive film. Relates to a device.

In general, a driving circuit of a TFT liquid crystal module includes a tape type flexible circuit board on which a driving LSI for driving a TFT is mounted, and a printed circuit board (PCB) for supplying power or image signals to the flexible circuit board. It consists of. Background Art Conventionally, anisotropic conductive films (ACFs) are often used for mounting flexible circuit boards to liquid crystal cells. With an anisotropic conductive film, electroconductive particle is disperse | distributed in the adhesive resin which has insulation, and has electroconductivity in the thickness direction (dependent direction).

In the modularization process in the manufacture of the liquid crystal display device, an anisotropic conductive film is attached to a connection terminal string formed on one substrate of a liquid crystal cell, for example, a TFT array substrate, which has relieved liquid crystal between a pair of transparent insulating substrates. The flexible circuit board is aligned with each other and press-fitted one by one. Thereafter, by heating and pressurizing the flexible circuit board using a heater tool, the adhesive resin of the anisotropic conductive film is thermally cured, and the conductive particles dispersed in the resin are connected to the lead terminals of the flexible circuit board and the connection terminal string of the TFT array substrate; It was sandwiched between and obtained both mechanical connection and electrical conduction at the same time.

Flexible circuit boards equipped with a driving LSI include a tape carrier package (TCP), a chip on film (COF), and the like, and any circuit board uses a polyimide film as a substrate, and copper foil is formed thereon to form a photolithography technology. The circuit pattern is formed by this. Moreover, the resin called a soldering resist is apply | coated to the circuit pattern formation surface for the purpose of insulation retention of a circuit, and protection from a foreign material. However, the conventional application area of the soldering resist was the circuit pattern part which removes the input terminal part for input and output of a flexible circuit board.

 In the conventional flexible circuit board, when the base substrate is bent on the back side (lower side) of the TFT array substrate, stress tends to concentrate on the edge portion of the TFT array substrate and the end portion of the solder resist, resulting in damage or disconnection of the circuit pattern. . These damages and disconnections occur when the flexible circuit board is bent or when the module is assembled, but they may be caused by vibration or shock even after the completion of the module. At this time, damage and disconnection of the circuit pattern of the flexible circuit board were often generated at the lead terminals at both ends where stress due to bending is particularly easy to concentrate.

In order to solve such a problem, for example, in Patent Document 1, a wiring board is arranged on the outer circumferential side of a pair of substrates (TFT array substrate) of a liquid crystal display panel through a paste or film adhesive (anisotropic conductive film). In the liquid crystal display device, the anisotropic conductive film is applied so as to be pushed outward from the outer peripheral edge of the TFT array substrate, so that even in the bending structure of the TCP mounting, the wiring of the wiring board is formed at the outer peripheral end of the TFT array substrate by the elasticity of the anisotropic conductive film. A liquid crystal display device which is not damaged or disconnected has been proposed.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-91015 (Page 3, FIG. 2)

However, in the structure by patent document 1, when the part which protruded from the anisotropic conductive film becomes too wide from the outer periphery of a board | substrate and extends to the back surface of a board | substrate, there exists a possibility that defects, such as a board | substrate cracking, may arise in a subsequent process. For this reason, there is a description that it is necessary to be about 0.1 mm to 1.0 mm from the substrate edge so that the range which is pushed out of the anisotropic conductive film does not become too large. However, with such a small pushed out dimension, the substrate end can be sufficiently covered. There is a possibility that there is no, or that sufficient elasticity cannot be expected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and in a liquid crystal display device in which a flexible circuit board is mounted on a connection terminal string formed on the outer peripheral portion of a TFT array substrate through an anisotropic conductive film, the stress of bending the flexible circuit board. An object of the present invention is to obtain a liquid crystal display device capable of preventing damage or disconnection of a circuit pattern of a flexible circuit board generated by the same.

A liquid crystal display device according to the present invention is a liquid crystal display device in which a flexible circuit board is disposed on an outer peripheral portion of a transparent insulating substrate provided with a display pixel electrode via an anisotropic conductive film, the flexible circuit board comprising: The solder resist for circuit protection is apply | coated to the pattern formation surface, or it has a junction part containing a lead terminal row electrically connected with a connection terminal row, and the part covered with solder resist in the part which overlaps with a transparent insulating board | substrate.

In the present invention, the stiffness (strength) of the bent portion of the flexible circuit board includes a portion overlapped with the transparent insulating substrate of the flexible circuit board, and has a portion covered with a solder resist for circuit protection, and includes a portion contacting the insulating portion of the transparent insulating substrate. ), It is difficult to buckle the circuit pattern of this part. As a result, damage or disconnection of the circuit pattern caused by the stress when bending the flexible circuit board can be prevented, the yield of the liquid crystal display device is improved, and the quality and reliability are improved.

[Examples of the Invention]

EMBODIMENT OF THE INVENTION Below, Example 1-Example 3 which is the best form for implementing this invention are described. First, the structure of the liquid crystal display panel in these Examples is briefly explained using FIG. 1 is a plan view showing a liquid crystal display panel constituting a liquid crystal display device in Embodiments 1 to 3. FIG. The liquid crystal display panel 10 includes a TFT array substrate 1 in which a thin film transistor, a display yo-pixel electrode, a protective film and an alignment film of a thin film transistor are sequentially formed on a transparent insulating substrate, and a black matrix and a color filter on the transparent insulating substrate. The counter electrode substrates 2, on which the protective film of the color filter, the common transparent pixel electrode, the alignment film, and the like are sequentially formed, are superposed so that the alignment films face each other, the peripheral portions of these substrates are actually bonded, and the liquid crystal is sealed between the two substrates. It is.

On the outer sides of both substrates of the liquid crystal display panel 10, polarizing plates 12 for polarizing light passing through the liquid crystal display panel 10 are respectively attached. In addition, a lead terminal for output of TCP 4, which is a flexible circuit board having flexibility, in which drive LSI 3 for driving a liquid crystal is mounted, is connected to a connection terminal string 11 formed at an outer circumferential portion of the TFT array substrate 1. have. In addition, a printed circuit board (PCB) 13 is connected to an input lead terminal of the TCP 4, and supplies an input signal to the TCP 4. The flexible TCP 4 is housed in a frame compactly in a curved shape on the lower substrate (TFT array substrate 1) side of the liquid crystal display panel 10.

(Example 1)

FIG. 2 is a plan view showing a flexible circuit board (TCP) mounting portion of a liquid crystal display device according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view of a portion shown as III-III in FIG. 2, and FIG. 4 is a liquid crystal in this embodiment. It is a top view which shows TCP used for a display apparatus. At this time, the same reference numerals are attached to the same and corresponding portions in the drawings.

The liquid crystal display panel constituting the liquid crystal display device according to the present embodiment is the same as the display panel 10 shown in FIG. 1, and part of the panel wiring such as gate wiring or source wiring provided on the TFT array substrate 1 is formed. The connection terminal string 11 is formed in the outer periphery of the substrate. In this connection terminal string 11, the TCP 4 which is a flexible circuit board is mounted via the anisotropic conductive film 8.

First, the modularization process in manufacture of a liquid crystal display device is demonstrated easily. The anisotropic conductive film 8 is attached to the connection terminal string 11 formed in the outer peripheral portion of the TFT array substrate 1, and the lead terminal string 42 (FIG. 4) for outputting the TCP 4 is aligned thereon and pressed one by one. Good. Thereafter, by heating and pressurizing the TCP 4 using a heater tool, the adhesive resin of the anisotropic conductive film 8 is thermally cured, and the conductive particles in the resin are the lead terminal rows 42 for outputting the TCP 4. And the connection terminal string 11 of the TFT array substrate 1 can be obtained simultaneously with mechanical bonding and electrical connection (conduction).

Next, the TCP 4 in the present embodiment will be described in detail with reference to FIG. In the TCP (4) according to the present embodiment, a circuit pattern made of copper foil is formed on the polyimide film (5) as the base material, and the drive LSI (3) for driving a liquid crystal is mounted on the circuit pattern (6). have. In addition, the input lead terminal string 41 and the output lead terminal string 42 in which a plurality of lead terminals are arranged in parallel with each other in the vicinity of the end faces 4a and 4b facing the TCP 4 are formed. The input lead terminal string 41 is electrically connected to the printed circuit board 13 (FIG. 1), and the output lead terminal string 42 is electrically connected to the connection terminal string 11 of the TFT array substrate 1, respectively.

Moreover, the soldering resist 7 for circuit protection which consists of insulating resin is apply | coated to the circuit pattern 6 formation surface of TCP4. In this embodiment, the solder resist 7 is applied so as to have a portion overlapping with the TFT array substrate 1 at both ends of the output lead terminal row 42 of the TCP 4. At this time, in FIG. 4, the dotted line 1A indicates the position of the edge 1a (FIG. 3) of the TFT array substrate 1, and the solder resist 7 located above the dotted line 1A is the TFT array substrate 1. Overlaps with

That is, the TCP 4 in this embodiment is electrically connected to the connection terminal string 11 of the TFT array substrate 1 at a portion overlapping with the TFT array substrate 1 (above the dotted line 1A in FIG. 4). It has a junction part including the lead terminal row 42 for output connected, and the part covered with the soldering resist 7.

Thus, the TFT array has a portion covered with the solder resist 7 at a portion overlapping with the TFT array substrate 1, in other words, a portion where the TFT array substrate 1 and the solder resist 7 overlap with each other. The rigidity (strength) of the bent portion of the TCP 4 including the portion in contact with the edge portion 1a of the substrate 1 can be increased, and the circuit pattern in the vicinity thereof is difficult to be buckled. Thereby, damage or disconnection of the circuit pattern 6 which arises by the stress at the time of bending TCP4 can be prevented. In addition, as shown in FIG. 3, in the part where the TFT array board | substrate 1 and the soldering resist 7 overlap, the edge part 1a of the TFT array board | substrate 1 is the circuit pattern 6 of TCP4 (for outputs). Since the lead terminals 42 are not in direct contact with each other, the circuit pattern 6 does not damage the substrate edge portion 1a.

At this time, in this embodiment, in the portion where TCP 4 overlaps with the TFT array substrate 1, the solder resist 7 has lead terminals 42a and 42b at least both ends of the output lead terminal string 42 (Fig. A plurality of lead terminals on the end side including 4)) were partially covered. However, it is not necessary to have a plurality of lead terminals partially covered by the solder resist 7, and may only cover one lead terminal 42a, 42b at each end. As a result, stress does not concentrate on the lead terminals 42a and 42b at both ends of the circuit pattern 6 of the TCP 4, where disconnection is most likely to occur, so that disconnection can be effectively prevented.

In the present embodiment, the solder resist 7 is in contact with the anisotropic conductive film 8 on the TFT array substrate 1 side at the portion where the TCP 4 overlaps the TFT array substrate 1. There is no contact with the terminal string 11. However, the plurality of lead terminals partially covered by the solder resist 7 may block the flow of the anisotropic conductive film 8 when the TCP 4 is pressed against the TFT array substrate 1 by the solder resist 7. In addition, since the electroconductive particle of the anisotropic conductive film 8 aggregates at the edge part of the soldering resist 7, the sheet | seat through electroconductive particle tends to generate | occur | produce between lead terminals.

As a countermeasure against such a short, all lead terminals including lead terminals 42a and 42b of both ends partially covered by the solder resist 7 may be coincidence wirings or dummy terminals. Alternatively, the coin wiring and the dummy terminal may be arranged in combination. In addition, by shortening the distance between the lead terminals, it is also possible to prevent a short between the terminals.

As described above, the liquid crystal display device according to the present embodiment is an output lead electrically connected to the connection terminal string 11 of the TFT array substrate 1 at a portion overlapping with the TFT array substrate 1 of the TCP 4. It has a junction part including the terminal row 42, and the part covered with the solder resist 7, In particular, in this embodiment, the solder resist 7 has lead terminals (at least at both ends of the output lead terminal row 42). The plurality of lead terminals including 42a and 42b) were partially covered. For this reason, it is possible to prevent stress from concentrating on the lead terminals 42a and 42b at both ends of the circuit pattern 6 of the TCP 4, where disconnection is most likely to occur. Damage and disconnection of the circuit pattern 6 of the TCP 4 caused by stress can be prevented. Accordingly, according to this embodiment, the yield of the liquid crystal display device is improved, and the quality and reliability are improved.

(Example 2)

5 is a plan view illustrating a flexible circuit board (TCP) mounting portion of a liquid crystal display according to a second exemplary embodiment of the present invention. In the drawings, the same reference numerals are attached to the corresponding parts. In this case, the configuration of the liquid crystal display device of the second embodiment is the same as that of the first embodiment except for the shape of the application area of the solder resist 7 applied to the circuit pattern 6 formation surface of the TCP (4). Therefore, explanation is omitted.

In the second embodiment, the TCP 4 in the second embodiment has an output lead terminal electrically connected to the connection terminal string 11 of the TFT array substrate 1 at the portion overlapping with the TFT array substrate 1 as in the first embodiment. It has a junction part containing the row 42 and a part covered with the soldering resist 7. Also in this embodiment, the solder resist 7 is applied so as to have a portion overlapping with the TFT array substrate 1 at both ends of the output lead terminal row 42 of the TCP 4. However, in this embodiment, in the part where the soldering resist 7 and the TFT array substrate 1 overlap, the edge part 7a of the soldering resist 7 is with respect to the edge part 1a of the TFT array substrate 1; It is formed to cross at an angle.

Conventionally, in TCP (4), when bending the polyimide film 5 which is a base base material to the back side (lower side) of the TFT array substrate 1, the edge part 1a of the TFT array substrate 1 and solder are carried out. Stress tended to concentrate on the end portion 7a of the resist 7, and damage and disconnection of the circuit pattern 6 of the TCP 4 occurred in these portions. Therefore, in the present embodiment, stress concentration on the solder resist end 7a is prevented by crossing the end 7a of the solder resist 7 obliquely with respect to the edge 1a of the TFT array substrate 1.

In addition, the end portion 7a of the solder resist 7 crosses the substrate edge portion 1a at an angle so that the portion where the TCP 4 and the TFT array substrate 1 overlap is partially formed by the solder resist 7. As a result, the area of the lead terminals covered by the structure can be reduced, and the short circuit between the lead terminals is less likely to occur than in the first embodiment.

As described above, also in the second embodiment, similar to the first embodiment, stress can be prevented from being concentrated on the lead terminals at both ends where the disconnection is most likely to occur in the circuit pattern 6 of the TCP 4. Damage or disconnection of the circuit pattern 6 of the TCP 4 caused by the stress at the time of bending (4) can be prevented. Accordingly, the yield of the liquid crystal display device is improved, and the quality and reliability are improved.

(Example 3)

6 is a plan view illustrating a flexible circuit board (TCP) mounting portion of a liquid crystal display according to a third embodiment of the present invention. In the drawings, the same reference numerals are assigned to the same and corresponding parts. In this case, the configuration of the liquid crystal display device according to the third embodiment is the same as that of the first embodiment except for the shape of the application area of the solder resist 7 applied to the circuit pattern formation surface of the TCP (4). Omit.

In the third embodiment, the TCP 4 is electrically connected to the connection terminal string 11 of the TFT array substrate 1 to a portion overlapping with the TFT array substrate 1, similarly to the first and second embodiments. It has a junction part including the lead terminal row 42 for output, and the part covered with the soldering resist 7. However, in the present embodiment, the solder resist 7 is coated so as to cover the TCP 4 end portion that is outside the lead terminals of both ends of the output lead terminal string of the TCP 4.

In this embodiment, the lead terminals at both ends of the output lead terminal string are not covered by the solder resist 7 and are not directly protected, but the solder resist 7 is applied to the polyimide films on both sides of the lead terminal string. As a result, the polyimide film 5 is reinforced, and the rigidity is increased. For this reason, the polyimide film 5 can be prevented from buckling at the edge portion 1a of the TFT array substrate 1, and the effect of preventing stress from concentrating on both ends of the lead terminal string adjacent to the reinforced portion. There is.

As described above, also in the third embodiment, stress concentration can be prevented in the lead terminals at both ends where disconnection is most likely to occur in the circuit pattern 6 of the TCP 4 as in the first and second embodiments. The damage and disconnection of the circuit pattern 6 of the TCP 4 caused by the stress when bending the TCP 4 can be prevented. In addition, since the solder resist 7 in the portion overlapping with the TFT array substrate 1 does not cover the lead terminal, a short circuit between terminals is unlikely to occur.

At this time, in Examples 1 to 3, three examples were shown as the application area of the solder resist 7 in the portion where TCP 4 overlaps with the TFT array substrate 1. However, in this invention, the shape of the application | coating area | region of the soldering resist 7 is not only what was shown in the said Example 1-Example 3. At least the shape which covers at least the lead terminal of the both ends of the lead terminal string 42 for output of the TCP 4, or the shape which covers the TCP 4 edge part more outer than the lead terminal of both ends, even if it is another shape, the said embodiment Almost the same effects as in the first to third embodiments can be obtained.

In the present invention, the stiffness (strength) of the bent portion of the flexible circuit board includes a portion overlapped with the transparent insulating substrate of the flexible circuit board, and has a portion covered with a solder resist for circuit protection, and includes a portion contacting the insulating portion of the transparent insulating substrate. ), It is difficult to buckle the circuit pattern of this part. As a result, damage or disconnection of the circuit pattern caused by the stress when bending the flexible circuit board can be prevented, the yield of the liquid crystal display device is improved, and the quality and reliability are improved.

INDUSTRIAL APPLICABILITY The present invention is used for a liquid crystal display device and can be used for a display device of a personal computer, a monitor, a display device of a television, and the like.

1 is a plan view showing a liquid crystal display panel in Examples 1 to 3 of the present invention.

Fig. 2 is a plan view showing a TCP mounting portion of the liquid crystal display device according to the first embodiment of the present invention.

3 is a cross-sectional view showing a TCP mounting portion of the liquid crystal display device according to the first embodiment of the present invention.

Fig. 4 is a plan view showing TCP which can be used for the liquid crystal display device according to the first embodiment of the present invention.

Fig. 5 is a plan view showing a TCP mounting portion of the liquid crystal display device according to the second embodiment of the present invention.

Fig. 6 is a plan view showing a TCP mounting portion of the liquid crystal display device according to the third embodiment of the present invention.

* Description of the symbols for the main parts of the drawings

1: TFT Array Substrate 1a: Short Edge

2: counter electrode substrate 3: driving LSI

4: TCP 4a, 4b: cross section

5: polyimide film 6: circuit pattern

7: solder resist 7a: end

8 anisotropic conductive film 10 liquid crystal display panel

11: connection terminal string 12: polarizing plate

13: printed circuit board 41: input lead terminal string

42: Output lead terminal string 42a, 42b: Lead terminal of both ends

Claims (5)

In a liquid crystal display device in which a flexible circuit board is disposed through an anisotropic conductive film on a connection terminal string formed on an outer periphery of a transparent insulating substrate provided with a display pixel electrode. The flexible circuit board is a bonded portion including a lead terminal string electrically connected to the connection terminal string at a portion where a solder resist for circuit protection is coated on the surface of the circuit pattern, and overlapping with the transparent insulating substrate, and the A liquid crystal display device having a portion covered with solder resist. The method of claim 1, The lead terminal string may include a plurality of lead terminals arranged in parallel with each other, and the solder resist may include the lead terminals at least both ends of the lead terminal string in a portion where the flexible circuit board overlaps the transparent insulating substrate. A liquid crystal display device which partially covers one or more of the lead terminals on an end side. The method of claim 2, And a plurality of lead terminals partially covered by the solder resist, the lead terminals are coincident with each other. The method of claim 2, And the lead terminal partially covered with the solder resist is a dummy terminal. The method of claim 1, The lead terminal array includes a plurality of lead terminals arranged in parallel with each other, and the solder resist is formed at a portion where the flexible circuit board overlaps with the transparent insulative substrate, and is further outside than the lead terminals at both ends of the lead terminal array. And an end portion of the flexible circuit board.