KR20060103665A - Flexible printed circuit film and liquid crystal display comprising the same - Google Patents

Abstract

Provided are a flexible printed circuit film having a misalignment structure and a liquid crystal display including the same. The flexible printed circuit film includes a body part capable of transmitting an electrical signal, a connection part formed on one side of the body part and electrically connected to the printed circuit board, and a closed curve for alignment with the first substrate of the liquid crystal display panel formed on the other side of the body part. And a pad portion having a plurality of alignment portions in the form and electrically connected to the first substrate.

Liquid crystal display, flexible printed circuit film, alignment

Description

Flexible printed circuit film and liquid crystal display comprising the same

1 is a perspective view illustrating a portion of a liquid crystal display according to an exemplary embodiment of the present invention.

2 and 3 are plan views of a flexible printed circuit film according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: liquid crystal display panel 102: first panel

104: second panel 112: gate driving IC

114: data driving IC 116: gate input pad

118: data input pad 120: alignment unit

200: printed circuit board 300: flexible printed circuit film

310: body portion 320: connection portion

330: pad portion 332: conductive pattern portion

334: alignment unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit film and a liquid crystal display device including the same. More particularly, the present invention relates to a flexible printed circuit film, and more particularly, to a flexible printed circuit film having a structure that prevents misalignment in connecting a liquid crystal display panel and a printed circuit board. The present invention relates to a printed circuit film and a liquid crystal display device including the same.

In general, a liquid crystal display device includes a liquid crystal display panel composed of a first substrate, a second substrate facing the first substrate, and a liquid crystal injected between the two substrates, and performs light modulation by a change in optical characteristics of the liquid crystal. It is a device that displays information by using.

In the first substrate, a plurality of gate lines and a plurality of data lines are formed to cross each other, and a thin film transistor and a pixel electrode as switching elements are formed in each of the crossed regions.

The data line receives a gray voltage selected from a source driving integrated circuit (IC) and transfers the gray voltage to the liquid crystal.

The gate line serves to open or close the thin film transistor, which is a switching element, in accordance with an on / off signal output from the gate driving IC.

Here, in order to apply a driving signal to the data line and the gate line, a printed circuit board (PCB) having various semiconductor elements and components mounted thereon, and a driving IC transferring the driving signal to the gate line and the data line And the liquid crystal display panel for displaying information are interconnected.

A method of interconnecting a liquid crystal display panel, a printed circuit board, and a driving IC is largely classified into a chip on glass (COG) mounting method and a tape automated bonding (TAB) mounting method.

The COG mounting method is a method in which a driving IC is mounted on a liquid crystal display panel and a liquid crystal display panel and a printed circuit board are connected by using a connector such as a flexible printed circuit film (FPC).

The conductor pattern for the electrical connection in the flexible printed circuit film and the liquid crystal display panel is formed with a very narrow line width, so that the flexible printed circuit film can be flexibly positioned to accurately position the liquid crystal display panel. Each alignment portion is formed on each side of the liquid crystal display panel to which the circuit film is attached and the flexible printed circuit film.

The flexible printed circuit film aligns the attachment position with the liquid crystal display panel by such an alignment portion, and thermal bonding is performed by pressing means to perform bonding.

At this time, the flexible printed circuit film may change the position of the alignment unit while thermal expansion occurs due to heat. In the case of a flexible printed circuit film that is conventionally used, the expansion degree due to thermal expansion cannot be predicted, and thus, the flexible printed circuit film is fixed to the flexible printed circuit film. It is difficult to apply shrinkage.

The technical problem to be achieved by the present invention is to provide a flexible printed circuit film having a misalignment structure.

Another object of the present invention is to provide a liquid crystal display device including the flexible printed circuit film as described above.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

A flexible printed circuit film according to an embodiment of the present invention for achieving the technical problem is a body portion capable of transmitting an electrical signal, the connection portion formed on one side of the body portion and electrically connected to the printed circuit board and the body And a pad part formed on the other side of the part, the pad part having a plurality of alignment parts in a closed curve shape for alignment with the first substrate of the liquid crystal display panel, and electrically connected to the first substrate.

According to another aspect of the present invention, a liquid crystal display device includes a liquid crystal between a first substrate having a driving IC mounted on one side of the substrate and the other side adjacent to the one side, and the first substrate. A liquid crystal display panel including a second substrate coupled to each other, a printed circuit board electrically connected to the first substrate and a body portion capable of transmitting electrical signals, formed on one side of the body portion and electrically connected to the printed circuit board And a flexible printed circuit film formed on the other side of the connecting portion and the body portion, the pad portion having a plurality of alignment portions in the form of closed curves for alignment with the first substrate and electrically connected to the first substrate.

Specific details of other embodiments are included in the detailed description and drawings.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view illustrating a portion of a liquid crystal display according to an exemplary embodiment of the present invention. In general, a liquid crystal display device includes a display unit for displaying information, a backlight assembly for supplying light to the display unit, a storage container housing the display unit and the backlight assembly, and fixing a portion of the display unit and combining with the storage container. It is composed of a chassis, for convenience, only a display unit is shown in FIG.

Referring to FIG. 1, a display unit of a liquid crystal display device may include a liquid crystal display panel 100 that receives an electrical signal from an external device and displays information, a printed circuit board 200 that transmits an electrical signal to the liquid crystal display panel 100, and A flexible printed circuit film 300 is connected to the liquid crystal display panel 100 and the printed circuit board 200 to drive the liquid crystal display panel 100.

The liquid crystal display panel 100 includes a first substrate 102, a second substrate 104 attached to face the first substrate 102, and a liquid crystal (not shown) injected between both substrates. The second substrate 104 is formed smaller than the size of the first substrate 102 so that a predetermined region of one end in the width direction and the length direction of the first substrate 102 is exposed to the outside of the second substrate 104.

A plurality of gate lines (not shown) are arranged in a line along the width direction on the first substrate 102, and a plurality of data lines (not shown) are arranged in a line along the length direction so as to intersect the gate lines. Are arranged. Thin film transistors and pixel electrodes (not shown), which are switching elements, are formed in each of the intersection regions of the gate lines and the data lines.

In the region exposed by the second substrate 104 of the first substrate 102, the gate lines and the source lines are driven to control the arrangement of the liquid crystal injected between the pixel electrode and the common electrode of the second substrate 104. The gate driver IC 112 and the source driver IC 114 are formed. Also adjacent to this are gate input pads 116 and data input pads 118.

Red, green, and blue pixels are formed on the second substrate 104 to pass through the light and express a predetermined color. The second substrate 104 is formed of indium tin oxide (ITO). A common electrode (not shown) is formed.

Reference numeral 120 denotes an alignment portion of the first substrate 102, which is used as an alignment mark when the flexible printed circuit film 300 is attached to the first substrate 120.

The printed circuit board 200 includes a gate printed circuit board electrically connected to the gate input pads 116 and a source printed circuit board electrically connected to the data input pads. Gate and source printed circuit boards are typically multi-layer printed circuit boards in which a plurality of substrates having conductor patterns formed thereon are stacked on top of each other, and the conductor patterns of each layer are electrically interconnected by via holes (not shown). Is formed.

The flexible printed circuit film 300 serves to electrically connect the printed circuit board and the gate input pads 116 and the data input pads 118 of the first substrate 102.

2 and 3 are plan views of the flexible printed circuit film included in the exemplary embodiment of the present invention, and show a surface attached to the first substrate of the liquid crystal display panel. For convenience of description, the case of connecting the gate printed circuit board and the flexible printed circuit film 300 is limited, but it can be applied to the source printed circuit board.

First, referring to FIG. 2, the flexible printed circuit film 300 may have an anisotropic conductive film (ACF) having flexibility and insulation, for example, a conductor pattern on a film having a polyimide material. To form a, it consists of a structure including a connection portion 320 and a pad portion 330 formed on one side and the other side of the body portion 310 with respect to the body portion 310 that can transmit electrical signals.

The connection part 320 formed on one side of the body part 310 of the flexible printed circuit film 300 is connected to the gate printed circuit board and is a part for electrical connection. The drive signal from the gate printed circuit board is transmitted through the connection 320. The connection part 320 includes a connection part 320a which serves to connect the gate printed circuit board and the flexible printed circuit film 300, and a connection part 320b which simultaneously performs an electrical connection and a connection role.

In addition, the pad part 330 formed on the other side of the body part 310 of the flexible printed circuit film 300 is connected to the first substrate 102 of the liquid crystal display panel and is a part for electrical connection.

The pad part 330 includes a conductive pattern part 332 and an alignment part 334.

The conductive line pattern portion 332 is a portion for electrical connection with the first substrate 102, and the gate driving signal from the gate printed circuit board is mounted on the gate driving IC 112 mounted on the first substrate 102. To pass. A plurality of conductive patterns are formed in the conductive pattern portion 332, and the conductive patterns are connected to the gate input patterns 116 on the first substrate 102.

The alignment unit 334 is a portion for accurate position alignment between the conductive line patterns included in the conductive line pattern unit 332 and the gate input pads 116 on the first substrate 102. The lead patterns of the lead pattern portion 332 and the gate input pads 116 are both formed with a very narrow line width, so that the alignment portion 334 of the closed curve shape may be formed in the pad portion 330 to accurately position them. Can be.

The alignment portion of the pad portion of the conventional flexible printed circuit film has a form open to the pad portion end side. Therefore, when attaching the connecting portion and the pad portion of the flexible printed circuit film to the gate printed circuit board and the first substrate, respectively, by the thermocompression bonding method, a force acts in the direction in which the pad portion concentrates to the alignment portion, and the connection portion and the body portion In the center of the flexible printed circuit film, a force is applied in a direction toward each side adjacent to one side and the other side of the body portion. Therefore, there is no specific direction of force that governs the entire flexible printed circuit film and thus the degree of expansion with respect to thermal expansion cannot be predicted.

Therefore, as illustrated in FIG. 2, the alignment unit 334 of the pad part 330 of the flexible printed circuit film 300 included in the exemplary embodiment of the present invention has a closed curve shape. In the case where the connecting portion 320 and the pad portion 330 of the flexible printed circuit film 300 are attached to the gate printed circuit board and the first substrate 102 by thermocompression bonding, the alignment portion of the pad portion 330 is provided. Since the shape of the 334 has a closed curve shape rather than an open shape, as shown by the arrow in FIG. 2, the body 310, the connecting portion 320, and the pad portion 330 all act in the same direction to apply heat. Since the expansion directions are the same, the degree of expansion with respect to thermal expansion of the flexible printed circuit film 300 can be predicted. Accordingly, the conductive pattern of the pad portion 330 of the flexible printed circuit film 300 due to the expansion of the flexible printed circuit film 300 during thermal compression may be adjusted by adjusting a gap between the alignment portions 334 by applying a constant shrinkage rate. And misalignment of the gate input pads 116 of the first substrate 102 with each other.

Thermal expansion of the flexible printed circuit film 300 is increased toward each side adjacent to one side and the other side of the body portion 310 in the center of the flexible printed circuit film 300.

Accordingly, the spacing between the alignment portions 334 of the flexible printed circuit film 300 is different from each other. Referring to FIG. 3, when the flexible printed circuit film 300 is made of a polyimide film, the region of I The spacing between the aligned alignments 334 is the same as that between the alignment portions 120 of the first substrate 102, and the spacing between the alignment portions 334 located in the region II is the alignment of the first substrate 102. The spacing between the alignment portions 334 located in the region III is 20 μm smaller than the spacing between the portions 120, and the spacing between the alignment portions 334 of the first substrate 120 is 50 μm smaller than the interval between the alignment portions 334. Can have That is, the distance between the alignment parts 334 decreases toward each side adjacent to one side and the other side of the body portion in the center of the flexible printed circuit film 300. The distance between the alignment portions 334 of the flexible printed circuit film 300 may vary depending on the material of the anisotropic conductive film constituting the flexible printed circuit film 300, and experimentally determined according to the degree of expansion of the film. Can be done.

Although the shape of the alignment portion 334 of the closed curve type as described above is not particularly limited, for example, the alignment portion 334 may have an oval shape having a short axis in a direction perpendicular to the end of the pad portion 330. At this time, the size of the alignment portion 334 of the closed curve shape, for example, the size of the alignment portion 334 of the elliptical shape is the alignment portion 120, for example rectangular alignment portion 120 of the first substrate 102 It has a size included in it.

Hereinafter, a method of thermocompression bonding the flexible printed circuit film 300 to the first substrate 102 will be described. For convenience of description, a method of thermocompression bonding the flexible printed circuit film 300 and the printed circuit board 200 will be omitted.

In order for the gate input pad 116 on the side where the gate driving IC 112 of the first substrate 102 is mounted and the conductive patterns of the flexible printed circuit film 300 to correspond, the first substrate 102 side. Alignment portion 334 formed in the center portion of, for example, alignment portion 334 formed in the center portion of the pad portion 330 of the flexible printed circuit film 300 in the alignment portion 120 of the rectangular shape, for example For example, the alignment unit 334 having an elliptic shape is aligned to be included in the alignment unit 120 having a rectangular shape of the first substrate 102.

Subsequently, the thermal pressurizing device is lowered to the pad portion 330 side of the flexible printed circuit film 300, so that the pad portion 330 of the flexible printed circuit film 300 and the gate input pads of the first substrate 102 ( 116). Then, the anisotropic conductive film is cured by the force applied by the thermal pressurization device and the high temperature heat generated from the surface of the thermal pressurization device, and the conductive patterns formed on the pad part 330 of the flexible printed circuit film 300 and Gate input pads 116 of the first substrate 102 are electrically connected.

At this time, in the alignment portion 334 of the pad portion 330 located in an area excluding the central portion of the flexible printed circuit film 300, the alignment portion 334 as the pad portion 330 is thermally expanded by the heat press device. ) Is equal to the distance between the alignment portions 120 formed on the first substrate 102, so that the conductive patterns of the flexible printed circuit film 300 and the gate input pads of the first substrate 102 are formed. Misalignment between 116 can be prevented.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

The liquid crystal display according to the exemplary embodiment of the present invention as described above includes a flexible printed circuit film having a structure capable of predicting a coefficient of thermal expansion, thereby forming conductive patterns of the pad portion of the flexible printed circuit and the liquid crystal display panel. By preventing misalignment between the gate of the first substrate and the data input pads, the defect caused by the flexible printed circuit film adhesion due to thermal expansion can be solved.

Claims (7)

A body part capable of transmitting an electrical signal; A connection part formed at one side of the body part and electrically connected to the printed circuit board; And And a pad portion formed on the other side of the body portion and having a plurality of alignment portions in the form of closed curves for alignment with the first substrate of the liquid crystal display panel and electrically connected to the first substrate. A liquid crystal display panel including a first substrate having a driving IC mounted on one side of the substrate and the other side adjacent to the one side, and a second substrate having a liquid crystal interposed therebetween with the first substrate; A printed circuit board electrically connected to the first substrate; And A body portion capable of transmitting an electrical signal, a connection portion formed on one side of the body portion and electrically connected to the printed circuit board, and a plurality of alignment parts formed on a closed side for alignment with the first substrate and formed on the other side of the body portion And a flexible printed circuit film including a pad portion electrically connected to the first substrate. The method of claim 2, And a gap between the plurality of alignment parts of the pad part. The method of claim 3, wherein And a gap between the plurality of alignment portions of the pad portion decreases from the center of the flexible printed circuit film toward each side adjacent to one side and the other side of the body portion. The method of claim 2, And the pad portion includes a conductor pattern portion for electrical connection with the liquid crystal display panel. The method of claim 2, And the alignment portion of the pad portion has an ellipse having a short axis in a direction perpendicular to an end of the pad portion. The method of claim 2, And the alignment portion of the pad portion is included in the alignment portion of the first substrate.

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