KR20070071378A - Flexible printed circuit and display device including the same - Google Patents

Abstract

A flexible printed circuit board and a display device including the same are provided to reduce thickness by removing a connector structure by bonding flexible printed circuit boards using an anisotropic conductive film. A flexible printed circuit board includes first and second flexible printed circuit boards(115,125). A first circuit pattern is formed on the first flexible printed circuit board, and a second circuit pattern is formed on the second flexible printed circuit board. An anisotropic conductive film(130) connects the first and second circuit patterns electrically. The first circuit pattern and the second circuit pattern have the same thickness and position of patterns.

Description

Flexible printed circuit board and display device having the same {Flexible Printed Circuit And Display Device Including the same}

1 is a perspective view showing a conventional display module.

2 schematically illustrates a display device using a flexible printed circuit board according to an exemplary embodiment of the present invention.

3 illustrates an example of the display panel of FIG. 2.

4 is a diagram illustrating a structure of a double-sided flexible printed circuit board of FIG. 2.

FIG. 5 is a diagram illustrating a circuit pattern of front and rear surfaces formed on a double-sided flexible printed circuit board of FIG. 2. FIG.

6 is a circuit pattern of a double-sided flexible printed circuit board according to another embodiment of the present invention.

7A and 7B illustrate front circuit patterns and back circuit patterns of the double-sided flexible printed circuit board of FIG. 6, respectively.

FIG. 8 is a view illustrating bonding using an anisotropic conductive film between a single-sided flexible printed circuit board formed on a display panel and a double-sided flexible printed circuit board formed on a set.

9 is a view showing the bonding using an anisotropic conductive film between the display panel and the cross-sectional flexible printed circuit board formed on each set.

 <Description of Symbols for Main Parts of Drawings>

10, 110: display panel 20, 120: set

130, 130a, 130b: anisotropic conductive film

115, 125, 116, 126: flexible printed circuit board

The present invention relates to a flexible printed circuit board, and more particularly, to a flexible printed circuit board having a wiring that can be fastened between the flexible printed circuit board using an anisotropic conductive film.

Recently, thanks to the development of various devices and materials that can be used in display devices, various display devices using each device and materials are being released one after another, and are now an important place as a medium for displaying media. I'm paginating.

Such display devices have been developed not only with CRT monitors but also with various display devices such as liquid crystal displays using liquid crystals, EL displays using electroluminescence, plasma display panels using plasma discharges, and FET flat panel displays using electric field effects. It is becoming. Among them, a liquid crystal display ("LCD") is a representative flat panel display that displays an image by adjusting the transmission amount of the light beam to correspond to an image signal. In particular, LCDs are in a trend of widening their application range due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are being applied as display devices for office automation devices and notebook computers. In addition, LCDs are progressing toward larger screens, higher resolutions, and lower power consumption in response to user demands. In addition to liquid crystal displays, EL displays have been becoming commercially available to obtain display panels of cell phone size as the low temperature crystallization technology of materials has developed.

Such a display device is a set in which a display panel 10 and a device for supplying various signals supplied to the display panel 10, for example, a power supply device and a signal supply source, are arranged as shown in FIG. 1. 20 and first and second flexible printed circuit boards 15 and 25 connecting the display panel 10 and the set 20 to each other.

As the display panel 10, various panels, such as an EL display panel, a liquid crystal display panel, and a FET panel, are applied, and a first flexible printed circuit board pad region 15a is formed on one side thereof in contact with the first flexible printed circuit board 15. do.

The set 20 includes a power supply for supplying various signals required for driving the display panel 10, a printed circuit board 22 including a timing controller, a data signal supply unit, and the like.

One side of the first flexible printed circuit board 15 of the first and second flexible printed circuit boards 15 and 25 is in contact with the first flexible printed circuit board pad area 15a formed in the display panel 10. The side is connected with a plug connector 18. One side of the second flexible printed circuit board 25 is in contact with the second flexible printed circuit board pad area 25a formed at one side of the printed circuit board 22, and the other side is connected to the socket connector 28. . The plug connector 18 connected to the first flexible printed circuit board 15 is connected to the socket connector 28 connected to the second flexible printed circuit board 25 to supply a signal and power to the display panel 10. The image will be implemented.

In the conventional first and second flexible printed circuit boards 15 and 25 coupling structure having such a structure, the plug connector 18 is inserted into the socket connector 28 so that the circuit connection is made.

Since the plug connector 18 is frequently separated from the socket connector 28, the problem of device failure in which the display panel 10 is whitened is rapidly increasing. Problems of the connector contact structure other than a separate display panel or a defect of the board may cause unnecessary AS of disassembling and reassembling the set, resulting in a huge amount of material and manpower waste. In addition, in the case of the display device having a problem of the connector contact structure, the same problem may occur again after the AS, which may cause a problem such as a decrease in customer reliability.

Accordingly, an aspect of the present invention is to provide a flexible printed circuit board having an improved connection structure between a board connecting a set and a display panel, and a display device having the same.

In order to achieve the above technical problem, the flexible printed circuit board according to the present invention is a first and second flexible printed circuit board; And an anisotropic conductive film formed on the first flexible printed circuit board and the second circuit pattern formed on the second flexible printed circuit board to electrically connect the second circuit pattern.

The first circuit pattern and the second circuit pattern are characterized in that the thickness and position of the pattern is the same.

At least one of the first and second flexible printed circuit boards may include a polyimide layer; First and second copper foil layers formed on both surfaces of the polyimide layer; First and second copper plating layers respectively formed on the first and second copper foil layers; And first and second coating layers formed on the first and second copper plating layers.

At least one of the first and second flexible printed circuit boards may include a polyimide layer; A copper foil layer formed on one surface of the polyimide layer; A copper plating layer formed on the copper foil layer; It is characterized by including a coating layer formed on the copper plating layer.

The first and second flexible printed circuit boards may be formed by removing an application layer in a region where the anisotropic conductive film is disposed.

At least one of the first and second flexible printed circuit boards may include via holes formed in the outermost region of the region in which the anisotropic conductive film is disposed.

When the first flexible printed circuit board is a cross-sectional type and the second flexible printed circuit board is a double-sided type, the third and fourth circuit patterns formed on the front and rear surfaces of the second flexible printed circuit board are thick and positioned. Is formed in a similar manner, and the circuit pattern bonded to the front surface of the second flexible printed circuit board among the cross-sections of the first flexible printed circuit board has a thickness and a position similar to that of the third circuit pattern, and the first flexible printed circuit board The circuit pattern bonded to the rear surface of the second flexible printed circuit board of the circuit board may have a thickness and a position similar to those of the fourth circuit pattern.

According to one or more exemplary embodiments, a display device including a flexible printed circuit board may include a display panel configured to implement an image; A first flexible printed circuit board formed on one side of the display panel; A set providing a driving signal and a power supply for driving the display panel; A second flexible printed circuit board formed on one side of the set and connected to the first flexible printed circuit board; And an anisotropic conductive film for electrically connecting the first and second circuit patterns respectively formed on the first and second flexible printed circuit boards.

Other technical problems and advantages of the present invention in addition to the above technical problem will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

2 is a diagram illustrating a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a display device according to an exemplary embodiment of the present invention includes a display panel 110 for implementing an image, a set 120 for supplying power and signals necessary for implementing the display panel 110, and a display panel 110. And a set 120 are connected to each other, and the first and second flexible printed circuit boards 115 and 125 are connected to each other using an anisotropic conductive film (ACF) 130.

The display panel 110 may be various display panels such as an EL (Electroluminescence) display panel, a liquid crystal display panel, a plasma display panel, a FET display panel, and the like. As an example of the display panel 110, the liquid crystal display panel includes a thin film transistor substrate 70 and a color filter substrate 80 bonded to each other with the liquid crystal 76 interposed therebetween as shown in FIG. 3. Can be formed. The color filter substrate 80 includes a black matrix 68 for preventing light leakage, a color filter 62 for implementing color, a common electrode 64 forming a vertical electric field with the pixel electrode 72, and a liquid crystal alignment on each component. A color filter array is formed on the upper substrate 11 including the upper alignment layer applied for the purpose. The thin film transistor substrate 70 includes a gate line 82 and a data line 74 formed to cross each other, a thin film transistor 58 formed at an intersection of the 82 and 74, and a thin film transistor 58 connected to the thin film transistor 58. A thin film transistor array including a pixel electrode 72 and a lower alignment layer coated for liquid crystal alignment on each component is formed on the lower substrate 21. The thin film transistor substrate also includes a gate pad 78 extending from the gate line 82, and a data pad 66 extending from the data line 74. On one side of the display panel 110, a drive IC which is in electrical contact with the gate pad and the data pad extending from the gate line 82 and the data line 74 is formed on the substrate, particularly the thin film transistor substrate 70. On one side of the IC, a first flexible printed circuit board pad region 115a for receiving the panel driving signal and power supplied from the set 120 is formed, and a first printed circuit board pad region 115a is provided on the first flexible printed circuit board pad region 115a. The flexible printed circuit board 115 is bonded.

The set 120 includes a space on which the display panel 110 is seated and a printed circuit board 122 including a power supply device, a timing controller, and a data signal supply unit for supplying various signals required for driving the display panel 110. And the like. In particular, the printed circuit board 122 disposed on the set 120 has a second flexible printed circuit board pad region 125a on which one side of the printed circuit board 122 contacts the second flexible printed circuit board 115.

At least one of the first and second flexible printed circuit boards 115 and 125 has a layer structure as shown in FIG. 4. In detail, when the first and second flexible printed circuit boards 115 and 125 according to the embodiment of the present invention are double-sided flexible printed circuit boards, the polyimide layer ( 100) first and second copper foil layers 102a and 102b formed on both surfaces, and first and second copper plating layers 104a formed on the first and second copper foil layers 102a and 102b, respectively. 104b), protecting the first and second coating layers 106a and 106b formed on the first and second copper plating layers 104a and 104b, and the first and second coating layers 106a and 106b as necessary. First and second silk layers 108a, 108b. In the case of the single-sided flexible printed circuit board structure, the polyimide layer 100 has a structure above or below the reference.

The polyimide layer 100 is a high temperature heating plastic resin used together with glass fibers to produce a laminated disc required for the production of multilayer flexible printed circuit boards, and is applied to other circuits requiring a function at a high temperature.

The first and second copper foil layers 102a and 102b are electrolytic copper foils used as conductors on a flexible printed circuit board and are made based on weight or thickness units.

The first and second copper plating layers 104a and 104b are plating layers using copper on the first and second copper foil layers 102a and 102b. Copper is easy to discolor in air, but has good thermal and electrical conductivity and is soft and easy to polish.

The first and second coating layers 106a and 106b are thin outer layers of an insulating material applied on a circuit formed of the first and second copper foil layers 102a and 102b and the first and second copper plating layers 104a and 104b. to be.

The first and second silk layers 108a and 108b are formed on the first and second coating layers 106a and 106b to prevent damage to the first and second coating layers 106a and 106b.

Between the first and second flexible printed circuit boards 115 and 125, the anisotropic conductive film 130 may contact the circuit patterns of the first and second flexible printed circuit boards 115 and 125. The first and second coating layers 106a and 106b in the region where 130 is disposed are removed. The anisotropic conductive film 130 is composed of a double-sided tape material in which an adhesive cured by zero and a fine conductive ball are mixed therein.The conductive ball in the portion where the pad of the circuit spanner is contacted when a high temperature is applied to the conductive ball is destroyed. The ball is energized between the pads, and the remaining adhesive is filled / hardened on the uneven surface other than the pad portion to adhere to each other.

The flexible printed circuit board coupling structure according to the embodiment of the present invention having the structure as described above is bonded by using the anisotropic conductive film 130 instead of using a separate plug connector and a socket connector. Regardless of the force generated by the movement of 110, the flexible printed circuit board coupling can be more firmly maintained, and the production cost can be reduced by not having a plug connector and a socket connector.

On the other hand, when the flexible printed circuit board according to the embodiment of the present invention is formed with different circuit patterns on both sides, as shown in Figure 5, a defect occurs in the coupling structure between the flexible printed circuit board using the anisotropic conductive film. . In detail, the front wiring and the back wiring overlap or partially overlap or do not overlap in the double-sided flexible printed circuit board. In this case, the thickness of the cross section is almost doubled since the copper wirings on both sides pass through the upper circuit pattern portion as compared to the lower circuit pattern portion. When the anisotropic conductive film is bonded in this structure, the thickness of the circuit pattern is nonuniform, so that conductive balls existing in the anisotropic conductive film at the time of bonding are not uniformly formed, and as a result, defects occur in the circuit connection between the pads.

In order to solve this problem, another embodiment of the present invention will propose a flexible printed circuit board having a symmetrical and uniform circuit wiring.

6 illustrates a flexible printed circuit board according to another exemplary embodiment of the present invention.

6, a double-sided FPC according to another embodiment of the present invention shows a double-sided flexible printed circuit board having a similar circuit pattern on the front and back. Here, in order to open the coating layer 106 formed on the front and back of the double-sided flexible printed circuit board to the maximum, the position of the via hole 112 is disposed at the outermost position. More specifically, the double-sided flexible printed circuit board may have a circuit pattern such as the front of the flexible printed circuit board shown in FIG. 7A and the rear of the flexible printed circuit board shown in FIG. Designed so that the thickness is same and located on the same line. Accordingly, the double-sided flexible printed circuit board of the present invention has a structure in which the front and rear circuit patterns are the same so that the pad portion receives a uniform load, and thus can support pressure evenly in all the portions.

The double-sided flexible printed circuit board according to another embodiment of the present invention having such a structure is connected to the set 120 and the single-sided flexible printed circuit board 116 and the anisotropic conductive films 130a and 130b formed on the display panel 110 are provided. As shown in FIG. 8, a portion of the cross-section flexible printed circuit board 116 formed on the display panel 110 is connected to the front surface of the double-sided flexible printed circuit board 125 and the display panel 110, as shown in FIG. 8. The remaining portion of the cross-section flexible printed circuit board 116 formed at the side may be connected to the back surface of the double-sided flexible printed circuit board 125. At this time, the coating layers formed on the cross-sections of the regions where the anisotropic conductive films 130a and 130b are disposed and the double-sided flexible printed circuit boards 116 and 125 are interposed between the circuit patterns formed on the single-sided and double-sided flexible printed circuit boards 116 and 125. It is removed for connection. The circuit patterns formed on the single-sided flexible printed circuit boards 125 and connected to the double-sided flexible printed circuit board 125 are formed to have a thickness and a position similar to those of the circuit patterns formed on the front and rear surfaces of the double-sided flexible printed circuit board 125. It is desirable to be.

The double-sided flexible printed circuit board according to another embodiment of the present invention has the same circuit pattern formed on the front and the back, so that the front and the back of the other flexible printed circuit board bonded at high temperature using an anisotropic conductive film. Regardless of the circuit pattern, the pressure can be evenly applied during bonding, so that the connection structure by the anisotropic conductive film is stably formed.

Meanwhile, in each embodiment of the present invention, the circuit patterns formed on the front and rear surfaces of the double-sided flexible printed circuit board are formed to be similar to each other. However, as shown in FIG. 9, the first and second single-sided flexible printed circuits are illustrated. One side of the substrate 116, 126 is connected to the set 120 and the display panel 110, respectively, and the other side of the first and second single-sided flexible printed circuit boards 116, 126 is formed using the anisotropic conductive film 130. When bonded, the circuit patterns formed on the other side of the first and second cross-sectional flexible printed circuit boards 116 and 126 are formed to have similar thicknesses and positions. In the flexible printed circuit board according to another embodiment of the present invention having the structure as described above, the anisotropic conductive film 130 disposed between the second flexible printed circuit board 126 and the first flexible printed circuit board 116 is hot pressed. The pressure applied between the first flexible printed circuit board 116 and the second flexible printed circuit board 126 is equally formed at the time when the contact point is formed by the conductive ball.

As described above, in the flexible printed circuit board and the display device having the same, the flexible printed circuit boards connecting the display panel and the set are bonded to each other using an anisotropic conductive film, thereby eliminating the connector structure to reduce thickness. It can secure the production cost by eliminating the connector. In addition, the flexible printed circuit board and the display device having the same according to the present invention can form a high temperature bonding structure using an anisotropic conductive film for connection between the flexible printed circuit boards, thereby maintaining the connection structure more firmly and preventing connection failure.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (10)

First and second flexible printed circuit boards; And A first circuit pattern formed on the first flexible printed circuit board and a second circuit pattern formed on the second flexible printed circuit board; And And an anisotropic conductive film for electrically connecting the first and second circuit patterns. The method of claim 1, The first circuit pattern and the second circuit pattern A flexible printed circuit board, characterized in that the thickness and position of the pattern is the same. The method of claim 1, At least one of the first and second flexible printed circuit boards Polyimide layer; First and second copper foil layers formed on both surfaces of the polyimide layer; First and second copper plating layers respectively formed on the first and second copper foil layers; And And a first and a second coating layer formed on the first and second copper plating layers. The method of claim 1, At least one of the first and second flexible printed circuit boards Polyimide layer; A copper foil layer formed on one surface of the polyimide layer; A copper plating layer formed on the copper foil layer; And A flexible printed circuit board comprising a coating layer formed on the copper plating layer. The method according to any one of claims 3 to 4, The first and second flexible printed circuit boards The flexible printed circuit board, characterized in that the coating layer of the region where the anisotropic conductive film is disposed is removed. The method of claim 1, At least one of the first and second flexible printed circuit boards The via hole is formed in the outermost region of the region where the anisotropic conductive film is disposed, the flexible printed circuit board. The method of claim 1, When the first flexible printed circuit board is a cross-sectional type, and the second flexible printed circuit board is a double-sided type, The third and fourth circuit patterns formed on the front and rear surfaces of the second flexible printed circuit board have similar thicknesses and positions, The circuit pattern bonded to the front surface of the second flexible printed circuit board among the cross-sections of the first flexible printed circuit board is formed to have a thickness and a position similar to that of the third circuit printed circuit board, and among the cross sections of the first flexible printed circuit board. The circuit pattern bonded to the rear surface of the second flexible printed circuit board has a thickness and a position similar to that of the fourth circuit pattern. A display panel for implementing an image; A first flexible printed circuit board formed on one side of the display panel; A set providing a driving signal and a power supply for driving the display panel; A second flexible printed circuit board formed on one side of the set and connected to the first flexible printed circuit board; First and second circuit patterns formed on the first and second flexible printed circuit boards, respectively; And An anisotropic conductive film for electrically connecting said 1st and 2nd circuit patterns, The display apparatus characterized by the above-mentioned. The method of claim 8, The first circuit pattern and the second circuit pattern A display device, characterized in that the thickness and position of the pattern are the same. The method of claim 8, When the first flexible printed circuit board is a cross-sectional type, and the second flexible printed circuit board is a double-sided type, The third and fourth circuit patterns formed on the front and rear surfaces of the second flexible printed circuit board have similar thicknesses and positions, The circuit pattern bonded to the front surface of the second flexible printed circuit board among the cross-sections of the first flexible printed circuit board is formed to have a thickness and a position similar to that of the third circuit printed circuit board, and among the cross sections of the first flexible printed circuit board. And a circuit pattern bonded to the rear surface of the second flexible printed circuit board to have a thickness and a position similar to those of the fourth circuit pattern.

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