WO2012161152A1 - Liquid crystal display device and electrical coupling structure - Google Patents

Abstract

An electrical coupling structure has: flexible substrates (10B, 20B), each comprising a single-sided wiring structure in which a conductive layer (12, 22) is formed on only one surface of a base film (11, 21); and solder (30) that joins the conductive layers (12, 22). The flexible substrate (20B) is folded back in a section where the conductive layer (22) is exposed to the flexible substrate (20B).

Description

Liquid crystal display device and electrical connection structure

The present invention relates to a liquid crystal display device and an electrical connection structure, and more particularly, to a liquid crystal display device including a flexible substrate and an electrical connection structure between flexible substrates.

A liquid crystal display device having a flexible substrate is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-20226 (Patent Document 1).

In Patent Document 1, in a liquid crystal module (1) having a main substrate (2) and a sub substrate (3), the sub substrate (3) is bent at the escape portion (A) and turned upside down. Thereby, the bent piece part (39) arranged in an overlapping manner on the main board (2) is formed on the sub board (3).

JP 2009-20226 A

In the structure described in Patent Document 1, the second electrode (35) formed on the bent piece (39) and the first electrode (25) formed on the main substrate (2) are bonded by pressure bonding. Yes. However, when this electrode is to be soldered, the joint is formed only on one side of the bent piece (39) (the portion where the first electrode (25) and the second electrode (35) face each other). Therefore, it is difficult to confirm soldering workability and soldering.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrical connection structure that facilitates soldering workability and confirmation of soldering, and a liquid crystal display device including the electrical connection structure. Is to provide.

A liquid crystal display device according to the present invention drives a liquid crystal panel, a liquid crystal driving device having a liquid crystal driving circuit for driving the liquid crystal panel, another electric device electrically connected to the liquid crystal panel, and another electric device. And another driving device having another driving circuit.

The liquid crystal driving device has a laminated structure including a first base layer, a first conductive layer that is provided on the first base layer, and that forms a liquid crystal driving circuit, and a first insulating layer that covers the first conductive layer. One conductive layer includes a first flexible substrate having a first joint exposed from the first insulating layer.

The other drive device includes a second base layer, a second conductive layer that is formed only on one side of the second base layer, and that constitutes another drive circuit, and a second insulating layer that covers the second conductive layer. A second flexible substrate having a structure and having a second joint electrically connected to the first joint is included.

In the liquid crystal display device, the liquid crystal driving device and the other driving device are electrically connected by soldering the first joint portion and the second joint portion, and in the second joint portion of the second flexible substrate, The second conductive layer is exposed from the second insulating layer, and the second flexible substrate is bent at a portion where the second conductive layer is exposed.

In one embodiment, in the liquid crystal display device, the first flexible substrate has a single-sided wiring structure in which the first conductive layer is formed only on one side of the first base layer.

In one embodiment, in the liquid crystal display device, the other electric device is a backlight that illuminates the liquid crystal panel, and the second conductive layer in the second flexible substrate constitutes a backlight driving circuit that drives the backlight. To do.

In one embodiment, in the liquid crystal display device, the other electrical device is a touch panel provided on the liquid crystal panel, and the second conductive layer in the second flexible substrate constitutes a touch panel drive circuit that drives the touch panel.

The electrical connection structure according to the present invention has a laminated structure including a first base layer, a first conductive layer provided on the first base layer, and a first insulating layer covering the first conductive layer. Includes a first flexible substrate having a first joint exposed from the first insulating layer, a second base layer, a second conductive layer formed only on one side of the second base layer, and a second covering the second conductive layer A second flexible substrate having a second joint portion, which has a single-sided wiring structure including an insulating layer and is electrically connected to the first joint portion, and a solder portion that joins the first joint portion and the second joint portion. Prepare.

In the electrical connection structure, in the second joint portion of the second flexible substrate, the second conductive layer is exposed from the second insulating layer, and the second flexible substrate is bent at a portion where the second conductive layer is exposed.

In one embodiment, in the above electrical connection structure, the first flexible substrate has a single-sided wiring structure in which the first conductive layer is formed only on one side of the first base layer.

According to the present invention, in an electrical connection structure included in a liquid crystal display device or the like, it is possible to easily confirm soldering workability and soldering while ensuring solder flow and bonding strength. In addition, since the electrical connection structure can be configured by a flexible substrate having a single-sided wiring structure, the manufacturing cost can be reduced.

It is a figure which shows the whole structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is a figure which shows the periphery (state before bending a flexible substrate) of the electrical-connection part of the flexible substrate contained in the liquid crystal display device shown in FIG. It is a figure which shows the periphery (state before soldering after bending a flexible substrate) of the electrical-connection part of the flexible substrate contained in the liquid crystal display device shown in FIG. It is a figure which shows the periphery of the electrical-connection part of the flexible substrate contained in the liquid crystal display device shown in FIG. 1, (a) is side sectional drawing, (b) is a top view. It is a figure which shows the periphery of the electrical-connection part of the flexible substrate contained in the liquid crystal display device which concerns on the comparative example 1, (a) is side surface sectional drawing, (b) is a top view. It is a figure which shows the periphery of the electrical-connection part of the flexible substrate contained in the liquid crystal display device which concerns on the comparative example 2, (a) is side sectional drawing, (b) is a top view. It is a figure which shows the periphery of the electrical-connection part of the flexible substrate contained in the liquid crystal display device which concerns on Embodiment 2 of this invention, (a) is side sectional drawing, (b) is a top view. It is a figure which shows the whole structure of the liquid crystal display device which concerns on Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described. Note that the same or corresponding portions are denoted by the same reference numerals, and the description thereof may not be repeated.

In the embodiment described below, when referring to the number, amount, etc., the scope of the present invention is not necessarily limited to the number, amount, etc. unless otherwise specified. In the following embodiments, each component is not necessarily essential for the present invention unless otherwise specified.

(Embodiment 1)
FIG. 1 is a diagram showing an overall configuration of a liquid crystal display device according to Embodiment 1 of the present invention. As shown in FIG. 1, the liquid crystal display device according to the present embodiment includes a liquid crystal panel 1A, a liquid crystal driving device 1B, a backlight device 2A (another electric device), and a backlight driving device 2B (another driving device). Device).

The liquid crystal panel 1A includes a liquid crystal layer, a color filter substrate, an array substrate (all including an alignment film), and a polarizing plate. The liquid crystal drive device 1B has a liquid crystal drive circuit that drives the liquid crystal panel 1A. The backlight device 2A is electrically connected to the liquid crystal panel 1A. The backlight driving device 2B has an electric circuit (another driving circuit) for driving the backlight device 2A.

The liquid crystal driving device 1B and the backlight driving device 2B each include a flexible printed circuit (FPC) that can be bent. That is, the liquid crystal display device according to the present embodiment includes an electrical connection structure between flexible substrates, and is characterized by the electrical connection structure.

Next, the structure around the electrical connection portion of the flexible substrate in the liquid crystal display device according to the present embodiment will be described with reference to FIGS.

2 to 4 are diagrams showing the periphery of the electrical connection portion. 2 shows a state before the flexible substrate 20B is bent, FIG. 3 shows a state before the flexible substrate 20B is bent and before soldering, and FIG. 4 shows a state where solder bonding is performed from the state of FIG. It shows the state after. 2 to 4, (a) is a side sectional view and (b) is a top view.

As shown in FIGS. 2 to 4, the electrical connection structure according to the present embodiment includes a flexible substrate 10B (first flexible substrate) and a flexible substrate 20B (second flexible substrate). The flexible substrate 10B is included in the liquid crystal driving device 1B, and the flexible substrate 20B is included in the backlight driving device 2B.

The flexible substrate 10B includes a base film 11 (first base layer), a conductive layer 12 (first conductive layer) that is provided on the base film 11 and forms a liquid crystal driving circuit, and an insulating layer 13 that covers the conductive layer 12 ( A first insulating layer). The flexible substrate 10 </ b> B has a joint portion 14 (first joint portion) in which the conductive layer 12 is exposed from the insulating layer 13.

The flexible substrate 20B includes a base film 21 (second base layer), a conductive layer 22 (second conductive layer) constituting an electric circuit for driving the backlight device 2A, and an insulating layer 23 (covering the conductive layer 22). A second insulating layer). The flexible substrate 20 </ b> B has a joint portion 24 (second joint portion) in which the conductive layer 22 is exposed from the insulating layer 23.

In the flexible substrates 10B and 20B, the conductive layers 12 and 22 are formed only on one side of the base films 11 and 21, respectively. That is, the flexible substrates 10B and 20B have a single-sided wiring structure in which wiring is formed only on one side of the base film.

In the liquid crystal display device according to the present embodiment, the joint 14 of the flexible substrate 10B and the joint 24 of the flexible substrate 20B are joined by the solder 30. Thereby, the liquid crystal drive device 1B and the backlight drive device 2B are electrically connected.

The electrical connection structure according to the present embodiment is characterized in that the flexible substrate 20B is bent at a portion where the conductive layer 22 of the flexible substrate 20B is exposed. The effect obtained by this feature will be described by comparing FIG. 4 with FIG. 5 (Comparative Example 1) and FIG. 6 (Comparative Example 2). 5 and 6, the same reference numerals as those in FIG. 4 are attached to the same or corresponding parts, and “α” (FIG. 5) and “β” are added respectively. (FIG. 6) is attached. 4 to 6, the end faces 31, 31α, 31β of the solder 30 are drawn in a straight line for convenience of illustration and explanation, but in actuality, they are formed in a slightly curved shape.

Incidentally, in Comparative Example 1 in FIG. 5, the flexible substrates 10α and 20α are both flexible substrates having a single-sided wiring structure. However, Comparative Example 1 in FIG. 5 differs from the present embodiment (FIG. 4) in that the flexible substrate 20α is not bent.

In the example of FIG. 5, the conductive layer 22α does not exist below the flexible substrate 20α (the side facing the flexible substrate 10α). Therefore, it is difficult for the solder 30α to flow into the portion where the flexible substrate 10α and the flexible substrate 20α face each other. As a result, the contact area between the solder 30α and the conductive layers 12α and 22α (particularly the conductive layer 22α) is reduced, the connection strength is reduced, and the connection reliability is lowered.

On the other hand, in the structure according to the present embodiment (FIG. 4), the flexible substrate 20B is bent at the portion (joint portion 24) where the conductive layer 22 of the flexible substrate 20B is exposed. The conductive layer 22 is also present (on the side facing the flexible substrate 10B), and the solder 30 is likely to flow into the portion where the flexible substrate 10B and the flexible substrate 20B are opposed. As a result, in the present embodiment, the reduction of the contact area between the solder 30 and the conductive layers 12 and 22 (particularly the conductive layer 22) is suppressed, the connection strength is increased, and the connection reliability is improved.

Further, in Comparative Example 2 in FIG. 6, the flexible substrate 20β is a flexible substrate on the double-sided wiring side. Therefore, in the example of FIG. 6, it is not difficult for the solder 30β to flow into the portion where the flexible substrate 10β and the flexible substrate 20β face each other. However, an increase in cost due to the use of a flexible substrate on the double-sided wiring side is inevitable.

On the other hand, in the structure (FIG. 4) according to the present embodiment, both the flexible substrates 10B and 20B have a single-sided wiring structure, so that the cost is suppressed compared to the comparative example 2 in FIG. Can do. That is, according to the electrical connection structure according to the present embodiment, it is possible to suppress the manufacturing cost while achieving the same connection strength as when the double-sided wiring type flexible substrate is used.

Furthermore, according to the electrical connection structure according to the present embodiment, the conductive layer 22 is exposed from the insulating layer 23 on the opposite side (upper side in FIG. 4) of the portion where the flexible substrate 10B and the flexible substrate 20B face each other. Therefore, it is possible to easily confirm the soldering workability and soldering.

As described above, according to the electrical connection structure according to the present embodiment, the manufacturing cost is reduced while ensuring the solder flow and the bonding strength, and the soldering workability and the confirmation of the soldering are easily performed. be able to.

As described above, there is a concern that the conductive layer 22 may be broken at the bent portion by bending the flexible substrate 20B. However, since the conductive layer 22 located on the lower side in FIG. 4 is formed for the purpose of increasing the contact area with the solder 30, an electric circuit for driving the backlight device 2A is provided in this portion. It is not necessary to have a function. Therefore, in the present embodiment, the electric circuit for driving the backlight device 2A is formed only in the portion located on the inner side with respect to the bent portion in the flexible substrate 20B, that is, the portion located on the upper side in FIG. It is preferable to keep it. By doing in this way, the damage of the electric circuit by bending the flexible substrate 20B can be prevented reliably.

(Embodiment 2)
7A and 7B are views showing the periphery of the electrical connection portion of the flexible substrate included in the liquid crystal display device according to the second embodiment, where FIG. 7A is a side sectional view and FIG. 7B is a top view.

The present embodiment is a modification of the first embodiment, and is characterized in that the length of the portion where the flexible substrate 10B and the flexible substrate 20B face each other is changed as shown in FIG.

Even in the structure shown in FIG. 7, as in the first embodiment, the manufacturing cost can be reduced while the solder flow and the bonding strength are ensured, and the soldering workability and the confirmation of soldering can be easily performed. Can do.

(Embodiment 3)
FIG. 8 is a diagram showing the overall configuration of the liquid crystal display device according to the third embodiment. The liquid crystal display device according to the present embodiment is a modification of the first and second embodiments, and a touch panel 3A is provided on a liquid crystal panel 1A.

In the present embodiment, the above-described structure is also applied to the connection between the touch panel driving device 3B that drives the touch panel 3A and the liquid crystal driving device 1B. That is, in the present embodiment, in addition to the backlight device 2A, the touch panel 3A also constitutes “another electrical device”, and in addition to the backlight drive device 2B, the touch panel drive device 3B also constitutes “another drive device”. ing.

In the present embodiment, since the backlight driving device 2B and the touch panel driving device 3B are provided so as to sandwich the liquid crystal driving device 1B, a double-sided wiring type flexible substrate is used for the liquid crystal driving device 1B. It is done.

Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The present invention can be used for a liquid crystal display device and an electrical connection structure.

1A liquid crystal panel, 1B liquid crystal drive device, 2A backlight device, 2B backlight drive device, 3A touch panel, 3B touch panel drive device, 10B, 20B flexible substrate, 11, 21 base film, 12, 22 conductive layer, 13, 23 insulation Layers, 14, 24 joints, 15 openings, 30 solder.

Claims (6)

Liquid crystal panel (1A),
A liquid crystal driving device (1B) having a liquid crystal driving circuit for driving the liquid crystal panel (1A);
Other electrical devices (2A, 3A) electrically connected to the liquid crystal panel (1A);
Other driving devices (2B, 3B) having other driving circuits for driving the other electric devices (2A, 3A),
The liquid crystal driving device (1B) is provided on the first base layer (11), the first base layer, the first conductive layer (12) constituting the liquid crystal driving circuit, and the first conductive layer (12). The first flexible substrate has a laminated structure including a first insulating layer (13) covering the first insulating layer (13), and the first conductive layer (12) has a first joint (14) exposed from the first insulating layer (13). (10B)
The other driving device (2B, 3B) is formed only on one side of the second base layer (21) and the second base layer (21), and the second conductive layer (22) constituting the other driving circuit. , And a second insulating layer (23) covering the second conductive layer (22), and a second junction (24) electrically connected to the first junction (14). A second flexible substrate (20B) having,
The liquid crystal driving device (1B) and the other driving devices (2B, 3B) are electrically connected by soldering the first joint (14) and the second joint (24). ,
In the second joint portion (24) of the second flexible substrate (20B), the second conductive layer (22) is exposed from the second insulating layer (23), and the second conductive layer (22) is exposed. The liquid crystal display device in which the second flexible substrate (20B) is bent at the portion where the step is performed. The liquid crystal display device according to claim 1, wherein the first flexible substrate (10B) has a single-sided wiring structure in which the first conductive layer (12) is formed only on one side of the first base layer (11). The other electric device is a backlight (2A) that illuminates the liquid crystal panel (1A),
The liquid crystal according to claim 1 or 2, wherein the second conductive layer (22) in the second flexible substrate (20B) constitutes a backlight driving circuit (2B) for driving the backlight (2A). Display device. The other electric device is a touch panel (3A) provided on the liquid crystal panel,
The liquid crystal display device according to claim 1 or 2, wherein the second conductive layer (22) in the second flexible substrate (20B) constitutes a touch panel drive circuit (3B) for driving the touch panel (3A). . A stack including a first base layer (11), a first conductive layer (12) provided on the first base layer (11), and a first insulating layer (13) covering the first conductive layer (12). A first flexible substrate (10B) having a structure, wherein the first conductive layer (12) has a first joint (14) exposed from the first insulating layer (13);
A second base layer (21), a second conductive layer (22) formed only on one side of the second base layer (21), and a second insulating layer (23) covering the second conductive layer (22) A second flexible substrate (20B) having a second joint portion (24) electrically connected to the first joint portion (14), comprising a single-sided wiring structure including:
A solder part (30) for joining the first joint part (14) and the second joint part (24);
In the second joint portion (24) of the second flexible substrate (20B), the second conductive layer (22) is exposed from the second insulating layer (23), and the second conductive layer (22) is exposed. The electrical connection structure in which the second flexible substrate (20B) is bent at the portion where the contact is made. The electrical connection structure according to claim 5, wherein the first flexible substrate (10B) has a single-sided wiring structure in which the first conductive layer (12) is formed only on one side of the first base layer (11).

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