KR20130131909A - Printed circuit board and liquid crystal display device including the same - Google Patents

Abstract

The present invention relates to a printed circuit board comprising a timing controller receiving a signal from outside and generating a control signal; and multiple transmitting wires for delivering the control signal from the timing controller to a gate driver and a data driver wherein the multiple transmitting wires form a transmission wire group by having two transmission wires to be formed in a pair for transmitting the control signal in a differential signal transmission method and coats a silk layer on the transmission wire group, where impedence irregularity occurs, of the transmission wire group.

Description

Printed circuit board and liquid crystal display device including the same}

An embodiment relates to a printed circuit board.

The embodiment relates to a liquid crystal display device.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. A flat panel display device including a thin liquid crystal display (LCD), a plasma display (PDP) or an organic electroluminescent device (OLED) which is thinner and lighter than a conventional cathode ray tube display (CRT) has been actively researched and commercialized . Of these, liquid crystal display devices are widely used today because of their advantages of miniaturization, light weight, thinness, and low power driving.

In general, a liquid crystal display device includes a printed circuit board having wirings for transmitting digital signals from the outside to the liquid crystal display panel. Recently, data signals are transmitted at high speed through wirings formed on the printed circuit board, and components to be mounted are also developed to respond at high speed. Each wire through which the data is transmitted is formed with an electric field induced by the flow of current, and the radiation of the electric field causes noise on signals transmitted to adjacent wires, thereby preventing the normal operation of components. May cause symptoms.

In order to solve the above problem, a method of transmitting a differential signal has been proposed.

1 is a waveform diagram of a differential signal transmitted in the prior art.

Referring to FIG. 1, a conventionally transmitted differential signal simultaneously transmits a positive signal S1 and a negative signal S2 having the same amplitude and opposite phase.

When the positive signal S1 and the negative signal S2 are simultaneously transmitted to adjacent transmission wires, the electric field generated in each of the adjacent transmission wires disappears by interaction. Specifically, when the positive signal S1 is converted from the low level to the high level, the negative signal S2 is converted from the high level to the low level. At this time, the directions of currents flowing in both transmission wirings are opposite to each other, and the electric field is canceled by forming the opposite direction of the electric field by the Fleming law.

The differential signal transmission method is widely used for communication equipment and the like. In particular, a liquid crystal display uses a low voltage differential signaling (LVDS) method or a reduced swing differential signaling (RSDS) method.

2 is a diagram illustrating a signal transmission of a conventional printed circuit board.

FIG. 2A is a cross-sectional view illustrating a conventional printed circuit board, and FIG. 2B is a diagram illustrating an impedance of a transmission wiring of a conventional printed circuit board.

Referring to FIG. 2A, a conventional printed circuit board includes a ground layer 40, a dielectric layer 13, an insulating layer 15, a first transmission line L1, and a second transmission line L2.

The printed circuit board is formed by sequentially stacking the ground layer 40, the dielectric layer 13, and the insulating layer 15. First and second transmission lines L1 and L2 may be formed on the dielectric layer 13. The first transmission line L1 and the second transmission line L2 may be formed at regular intervals. The positive signal S1 of FIG. 1 may be transmitted to the first transmission line L1, and the negative signal S2 of FIG. 1 may be transmitted to the second transmission line L2.

The ground layer 40 forms an electric field in a relationship between the first transmission line L1 and the second transmission line L2 with the dielectric layer 13 interposed therebetween, so that the first and second transmission lines L1 are formed. , L2) reduces the impedance.

Referring to FIG. 2B, if the impedances of the first and second transmission lines L1 and L2 are measured, 98.34Ω is measured. In general, when a printed circuit board transmits a signal from a transmitter to a receiver through a transmission line, impedances of the transmitter, the receiver, and the transmission line should be matched to minimize distortion of the signal. This is called impedance matching. According to the HDMI (High Definition Multimedia Interface) standard, the impedance should be designed to be within 100Ω ± 15% for impedance matching of transmission wiring. As the impedance of transmission wiring approaches 100Ω, signal distortion does not occur.

However, in recent years, researches for reducing the thickness of printed circuit boards have been actively conducted according to the trend toward thinner and lighter weight liquid crystal displays, and in particular, a printed circuit board having omitted the ground layer 40 has been developed.

3 is a view illustrating a printed circuit board with a conventional ground layer removed.

FIG. 3A is a cross-sectional view illustrating a printed circuit board with a conventional ground layer removed, and FIG. 3B is a diagram illustrating an impedance of a transmission wiring of a printed circuit board with a conventional ground layer removed.

Referring to FIG. 3A, a conventional printed circuit board includes a dielectric layer 13, an insulating layer 15, a first transmission line L1, and a second transmission line L2.

In the printed circuit board, a dielectric layer 13 and an insulating layer 15 may be sequentially formed, and a first transmission line L1 and a second transmission line L2 may be formed on the dielectric layer 13. The printed circuit board can reduce the thickness of the printed circuit board by omitting the ground layer as compared to FIG. 1.

Referring to FIG. 3B, when the impedances of the first and second transmission lines L1 and L2 are measured, 110.34Ω is measured. In this case, there is a problem in that signal distortion occurs due to a mismatch between impedances of the transmitter, the receiver, and the transmission wiring.

The embodiment provides a printed circuit board and a liquid crystal display device which can improve signal quality by preventing signal distortion.

The embodiment provides a printed circuit board and a liquid crystal display device which can be reduced in thickness and weight.

A printed circuit board according to an embodiment includes a timing controller configured to receive a signal from an external source and generate a control signal; And a plurality of transmission wires for transferring the control signal from the timing controller to a gate driver and a data driver, wherein the plurality of transmission wires are provided by two transmission wires for transmitting the control signal by a differential signal transmission method. It is formed in pairs to form a transmission wiring group, and a silk layer is applied on the transmission wiring group in which impedance discontinuities appear in the transmission wiring group.

In an embodiment, a liquid crystal display device includes: a printed circuit board including a timing controller; A liquid crystal display panel including an array substrate and a color filter substrate; A flexible circuit board connecting the liquid crystal display panel and the printed circuit board and having a data driver mounted thereon; And a plurality of transmission wires for transmitting a control signal from the timing controller to the data driver, wherein the plurality of transmission wires are formed by pairing two transmission wires to transmit the control signal by a differential signal transmission method. A transmission wiring group is formed, and a silk layer is coated on the transmission wiring group in which impedance discontinuities appear in the transmission wiring group.

In the printed circuit board and the liquid crystal display according to the exemplary embodiment, a silk layer or a protruding region is formed on a transmission line pair in which impedance discontinuity occurs, thereby matching impedance, thereby preventing signal distortion and improving image quality.

In the printed circuit board and the liquid crystal display according to the embodiment, impedance matching is performed using a silk layer formed to prevent a solder trapped shape in the soldering process, so that the ground layer is removed and signal distortion can be prevented without adding a separate process. Therefore, process cost can be reduced, and printed circuit boards and liquid crystal display devices can be made thin.

1 is a waveform diagram of a differential signal transmitted in the prior art.
2 is a diagram illustrating a signal transmission of a conventional printed circuit board.
3 is a view illustrating a printed circuit board with a conventional ground layer removed.
4 is a diagram illustrating a liquid crystal display according to a first embodiment.
5 is a diagram illustrating a printed circuit board of the liquid crystal display according to the first embodiment.
6 is a view illustrating a method of manufacturing a printed circuit board of the liquid crystal display according to the first embodiment.
7 is a cross-sectional view illustrating a printed circuit board of a liquid crystal display according to a second embodiment.
8 is a view illustrating a method of manufacturing a printed circuit board of the liquid crystal display according to the second embodiment.
9 illustrates a flexible circuit board of a liquid crystal display according to a third embodiment.
10 is a diagram illustrating a liquid crystal display according to a fourth embodiment.

A printed circuit board according to an embodiment includes a timing controller configured to receive a signal from an external source and generate a control signal; And a plurality of transmission wires for transferring the control signal from the timing controller to a gate driver and a data driver, wherein the plurality of transmission wires are provided by two transmission wires for transmitting the control signal by a differential signal transmission method. It is formed in pairs to form a transmission wiring group, and a silk layer is applied on the transmission wiring group in which impedance discontinuities appear in the transmission wiring group.

The silk layer may serve to prevent a solder trapped shape in the soldering process.

The silk layer may be formed of a material including an epoxy.

The silk layer may be applied to the entire area where the plurality of transmission wirings are formed.

The differential signal transmission method may be a Low Voltage Differential Signaling (LVDS) method or a Reduced Swing Differential Signaling (RSDS) method.

In an embodiment, a liquid crystal display device includes: a printed circuit board including a timing controller; A liquid crystal display panel including an array substrate and a color filter substrate; A flexible circuit board connecting the liquid crystal display panel and the printed circuit board and having a data driver mounted thereon; And a plurality of transmission wires for transmitting a control signal from the timing controller to the data driver, wherein the plurality of transmission wires are formed by pairing two transmission wires to transmit the control signal by a differential signal transmission method. A transmission wiring group is formed, and a silk layer is coated on the transmission wiring group in which impedance discontinuities appear in the transmission wiring group.

The silk layer may serve to prevent a solder trapped shape in the soldering process.

The printed circuit board may include a dielectric layer for maintaining a shape of the printed circuit board; And an insulating layer formed on the dielectric layer to insulate a plurality of transmission wirings from the outside, wherein the plurality of transmission wirings are formed on the dielectric layer, and the silk layer may be formed on the insulating layer.

The silk layer may be formed of the same material as the insulating layer.

The silk layer may be applied to a region of the transmission wiring group corresponding to the transmission wiring group in which the ground layer is not formed on the rear surface of the dielectric layer.

The insulating layer may have a thickness of 15 μm to 25 μm and the silk layer may have a thickness of 10 μm to 20 μm.

The spacing between each transmission wiring group may be wider than the spacing between a pair of transmission wirings constituting each transmission wiring group.

The silk layer may be formed on a transmission wiring group formed on the flexible circuit board to connect the printed circuit board and the data driver.

The array substrate includes: a gate driver generating a gate signal from a gate control signal; And a plurality of connection wires connecting the flexible printed circuit board and the gate driver, wherein the plurality of connection wires are connected to each other by a pair of connection wire groups in order to transmit the gate control signal by a differential signal transmission method. The silk layer may be formed on a connection wiring group in which impedance discontinuity is present in the connection wiring group.

The gate control signal may be transmitted through the flexible circuit board.

The spacing between each connection wiring group may be wider than the spacing between a pair of connection wirings constituting each connection wiring group.

4 is a diagram illustrating a liquid crystal display according to a first embodiment.

Referring to FIG. 4, the liquid crystal display according to the first exemplary embodiment may include a liquid crystal display panel 1, a printed circuit board 10, and a flexible circuit board 20.

The liquid crystal display panel 1 and the printed circuit board 10 may be connected by a plurality of flexible printed circuit boards 20. The plurality of flexible printed circuit boards 20 and the liquid crystal display panel 1 may be attached by an anisotropic conductive film (ACF). The plurality of flexible printed circuit boards 20 and the printed circuit board may be attached. (10) It may also be attached with an anisotropic conductive film.

The liquid crystal display panel 1 may include an array substrate and a color filter substrate, and a plurality of gate lines and data lines may be formed on the array substrate to define a pixel region. Thin film transistors connected to the gate line and the data line may be formed in the pixel area, and gate signals and data signals applied to the gate line and the data line may be transferred from the printed circuit board 10 to the flexible circuit board. It may be transmitted to a gate driver (not shown) and a data driver 21 connected to the gate line and the data line, respectively, via 20.

The timing controller 11 may be formed on the printed circuit board 10. The timing controller 11 receives a digital video data RGB, a horizontal synchronizing signal H, a vertical synchronizing signal H, V, and a clock signal CLK from an external source, and controls the gate driver. In addition to generating GDC, a data control signal DDC for controlling the data driver 21 is generated. The timing controller 11 also supplies data RGB from the system to the data driver 21. The data control signal DDC is supplied to the data driver 21 including a source shift clock SSC, a source start pulse SSP, a polarity control signal POL, a source output enable signal SOE, and the like. The gate control signal GDC is supplied to the gate driver including a gate start pulse GSP, a gate shift clock GSC, a gate output enable GOE, and the like.

A plurality of transmission lines L1 to Ln for transmitting signals from the timing controller 11 to the flexible circuit board 20 may be formed on the printed circuit board 10.

The data driver 21 may be mounted on the flexible printed circuit (FPC) 20. The data driver 21 generates a data voltage through data control signals DDC and data RGB transmitted from the timing controller 11 of the printed circuit board 11 to the plurality of transmission lines L1 to Ln. As a result, the data line may be transferred to the thin film transistor through the data line formed on the liquid crystal display panel 1.

5 is a diagram illustrating a printed circuit board of the liquid crystal display according to the first embodiment.

5A is a cross-sectional view illustrating a printed circuit board of the liquid crystal display according to the first embodiment, and FIG. 5B is a diagram illustrating an impedance of a transmission wiring of the printed circuit board formed according to the first embodiment.

Referring to FIG. 5A, the printed circuit board 10 of the liquid crystal display according to the first exemplary embodiment may include a dielectric layer 13, an insulating layer 15, first to sixth transfer wirings L1 to L6, and a silk layer 17. ) May be included.

The printed circuit board 10 may be formed by sequentially stacking the dielectric layer 13, the insulating layer 15, and the silk layer 17.

The dielectric layer 13 may be formed of a thermosetting resin having a hardness of a predetermined level or more to maintain the shape of the printed circuit board 10. The dielectric layer 13 may be formed of an insulating material including epoxy or phenol.

First to sixth transmission lines L1 to L6 may be formed on the dielectric layer 13. Although a plurality of transmission wirings are formed on the dielectric layer 13, the first to sixth transmission wirings L1 to L6 will be described in the drawings. In the first to sixth transmission wires L1 to L6, two transmission wires may be formed as a pair for a differential signal transmission method. In other words, the first and second transmission wirings L1 and L2 are formed in a pair, and the third and fourth transmission wirings L3 and L4 are formed in a pair, and the fifth and sixth transmission wirings are formed. L5 and L6 may be formed in pairs.

The pair of transmission wirings, for example, the first and second transmission wirings L1 and L2 may be formed at regular intervals to cancel the electric field. In addition, a predetermined interval may be formed between each pair of transmission wirings to prevent the influence of signal interference and electric field. In other words, the interval between the pair of first and second transmission lines L1 and L2 is between the second transmission line L2 and the third transmission line L3, which are intervals between the transmission lines included in another adjacent pair. It may be formed narrower than the interval of. The pair of transmission wires may transmit signals in a differential signal transmission method. For example, the positive signal S1 and the negative signal S2 as shown in FIG. 1 may be simultaneously transmitted to the first and second transmission lines L1 and L2. Specifically, when the positive signal S1 is converted from the low level to the high level, the negative signal S2 is converted from the high level to the low level. At this time, the directions of currents flowing in both transmission wirings are opposite to each other, and the electric field is canceled by forming the opposite directions in the electric field direction by the Fleming law.

The differential signal transmission method is widely used for communication equipment and the like, and in particular, a liquid crystal display device may use a low voltage differential signaling (LVDS) method or a reduced swing differential signaling (RSDS) method.

The first to sixth transmission wirings L1 to L6 may be formed of a conductor such as Cu.

The insulating layer 15 may be formed on the entire surface of the dielectric layer 13 on which the first to sixth transmission lines L1 to L6 are formed. The insulating layer 15 serves to protect the first to sixth transmission wires L1 to L6 from an external material and to insulate the first to sixth transmission wires L1 to L6 from the outside. can do. The insulating layer 15 may be formed of a material including epoxy. The insulating layer 15 may be formed to have a first thickness d1. The first thickness d1 may be 15 μm to 25 μm.

The pair of transmission wires transmitted by the differential signal transmission method, for example, impedances of the first and second transmission wires L1 and L2 may be the thickness of the dielectric layer 13 and the first and second transmission wires L1. , Proportional to L2). In addition, the impedances of the first and second transmission wirings L1 and L2 may include a dielectric constant of the dielectric layer 13, a dielectric constant of the insulating layer 15, a thickness d1 of the insulating layer 15, the first and second The width is in inverse proportion to the widths of the second transmission lines L1 and L2.

The printed circuit board 10 according to the first embodiment has no ground layer as compared with the prior art, and thus, the impedance of the transmission line is reduced to prevent signal distortion for impedance matching of the transmission line between the transmitter and the receiver. The purpose.

The silk layer 17 may be formed in a portion of the insulating layer 15. The silk layer 17 may be formed in a region corresponding to the transmission wiring formed in pairs. The silk layer 17 may be formed in the upper region of the transmission wiring pair in which impedance is discontinuous. Since the printed circuit board 10 according to the first embodiment of the present invention may have a region where a ground layer is formed and a region where the ground layer is not formed, the printed circuit board 10 may be formed in an upper region of a transmission line pair corresponding to the region where the ground layer is not formed. have. For example, as shown, when impedance discontinuity occurs in a pair of transmission lines including the third transmission line L3 and the fourth transmission line L4, the third transmission line L3 and the fourth transmission line are shown. The silk layer 17 may be formed on the insulating layer 15 corresponding to (L4).

The silk layer 17 may be formed of a material including an epoxy. The silk layer 17 may be formed of the same material as the insulating layer 15. The silk layer 17 serves to prevent a solder bridge shape between the circuit and the circuit in a soldering process performed during component mounting in a later process or to form another pattern. The printed circuit board 10 according to the first exemplary embodiment may form the silk layer 17 in an upper region of a transmission line pair in which impedance is discontinuous so that impedance matching may be performed without adding an additional layer. ), The image quality is improved by thinning and preventing signal distortion.

The silk layer 17 may be formed to a second thickness d2. By forming the silk layer 17 to a second thickness d2, the insulating layer 15 and the second thickness having a first thickness d1 are formed on the third transmission line L3 and the fourth transmission line L4. The silk layer 17 which has (d2) is formed. Since the impedances of the third and fourth transmission lines L3 and L4 are inversely proportional to the thickness of the insulating layer 15, the second thickness d2 is formed on the insulating layer 15 having the first thickness d1. The impedance of the third and fourth transmission wires L3 and L4 can be reduced by forming the silk layer 17 having a. The second thickness d2 may be 10 μm to 20 μm.

Referring to FIG. 5B, when the third and fourth transmission wires L3 and L4 of the printed circuit board 10 according to the first embodiment are measured, 99.43Ω is measured.

Compared to the transmission wiring of the conventional printed circuit board having an impedance of 110.34Ω shown in FIG. 3, a result value which is significantly close to 100Ω can be obtained. According to the HDMI (High Definition Multimedia Interface) standard, the impedance should be designed to be within 100Ω ± 15% for impedance matching of transmission wiring. As the impedance of transmission wiring approaches 100Ω, signal distortion does not occur. The third and fourth transmission wirings L3 and L4 of the printed circuit board 10 according to the first exemplary embodiment may partially remove the ground layer from the silk layer 17 in the transmission wiring region where impedance mismatch occurs. By matching the impedance, it is possible to improve the image quality by preventing the signal distortion by matching the impedance, and contribute to the thinning of the printed circuit board 10 by removing the ground layer.

6 is a view illustrating a method of manufacturing a printed circuit board of the liquid crystal display according to the first embodiment.

Referring to FIG. 6A, in the method of manufacturing a printed circuit board of the liquid crystal display according to the first embodiment, a dielectric layer 13 is formed, and a metal layer 14 is coated on the dielectric layer 13.

The dielectric layer 13 may be formed of a thermosetting resin having a hardness of a predetermined level or more to maintain the shape of the printed circuit board. The dielectric layer 13 may be formed of an insulating material including epoxy or phenol.

The metal layer 14 may be applied by a sputtering method. The metal layer 14 may be formed of a conductor including Cu and the like.

Referring to FIG. 6B, in the method of manufacturing a printed circuit board of the liquid crystal display according to the first exemplary embodiment, the metal layer 14 is patterned to form first to sixth transfer wirings L1 to L6. In the first to sixth transmission wires L1 to L6, two transmission wires may be formed as a pair for a differential signal transmission method. In other words, the first and second transmission wirings L1 and L2 are formed in a pair, and the third and fourth transmission wirings L3 and L4 are formed in a pair, and the fifth and sixth transmission wirings are formed. L5 and L6 may be formed in pairs. The distance between the pair of first and second transmission lines L1 and L2 is greater than the distance between the second transmission line L2 and the third transmission line L3, which is an interval between transmission lines included in another adjacent pair. It may be narrowly formed.

Referring to FIG. 6C, in the method of manufacturing a printed circuit board of the liquid crystal display according to the first exemplary embodiment, the insulating layer may be formed on the entire surface of the dielectric layer 13 on which the first to sixth transfer wirings L1 to L6 are formed. 15) can be formed. The insulating layer 15 serves to protect the first to sixth transmission wires L1 to L6 from an external material and to insulate the first to sixth transmission wires L1 to L6 from the outside. can do. The insulating layer 15 may be formed of a material including epoxy.

Referring to FIG. 6D, in the method of manufacturing a printed circuit board of the liquid crystal display according to the first exemplary embodiment, the silk material 16 is coated on the entire surface of the insulating layer 15.

The silk material 16 may be applied to the entire surface by a screen method or a spray coating method.

The photoresist 42 is applied to the upper surface of the printed circuit board on which the silk material 16 is applied, and the mask 19 is positioned on the photoresist 42. Ultraviolet (UV) rays are irradiated onto the mask 19 in the direction of the photoresist 42. The mask 19 may include a light blocking portion 19a and a transmission portion 19b. The light blocking unit 19a may serve to block ultraviolet rays (UV), and the transmission unit 19b may transmit the ultraviolet rays (UV). The transmission unit 19b is positioned to correspond to the third and fourth transmission wirings L3 and L4 and is irradiated with ultraviolet rays. The photoresist 42 irradiated with ultraviolet rays is changed in molecular structure by the ultraviolet rays (UV), and a portion of the photoresist 42 and the silk material 16 is removed by using a developer after the ultraviolet irradiation. A printed circuit board including a silk layer 17 such as 6e is formed.

In FIG. 6D, a negative photoresist leaving a region to which light is irradiated is described, but a printed circuit board including the silk layer 17 may be formed using a positive photoresist that removes a pattern of a region to which light is irradiated. have.

7 is a cross-sectional view illustrating a printed circuit board of a liquid crystal display according to a second embodiment.

The printed circuit board of the liquid crystal display according to the second embodiment is the same as the first embodiment except that no silk layer is formed and a protruding region protruding from the insulating layer is formed. Therefore, in describing the second embodiment, detailed description of parts common to the first embodiment will be omitted.

Referring to FIG. 7, the printed circuit board 10 of the liquid crystal display according to the second exemplary embodiment may include a dielectric layer 113, an insulating layer 115, first to sixth transfer wirings L1 to L6, and a protruding region 118. ) May be included.

The printed circuit board 10 may be formed by sequentially stacking the dielectric layer 113 and the insulating layer 115. First to sixth transmission lines L1 to L6 may be formed on the dielectric layer 113. In the first to sixth transmission wires L1 to L6, two transmission wires may be formed as a pair for a differential signal transmission method. In other words, the first and second transmission wirings L1 and L2 are formed in a pair, and the third and fourth transmission wirings L3 and L4 are formed in a pair, and the fifth and sixth transmission wirings are formed. L5 and L6 may be formed in pairs. The pair of transmission wires may transmit signals in a differential signal transmission method.

The insulating layer 115 may be formed on the entire surface of the dielectric layer 113 on which the first to sixth transmission lines L1 to L6 are formed. The insulating layer 115 may include a protruding region 118 protruding in the opposite direction of the dielectric layer 113. The protruding region 118 may be formed in an area corresponding to the transmission wiring formed in pairs. The protruding region 118 may be formed in an upper region of the transmission line pair having an impedance discontinuity. Since the printed circuit board 10 of the second embodiment may have a region where a ground layer is formed and a region where a ground layer is not formed, the protruding region is formed in an upper region of a transmission line pair corresponding to a region where the ground layer is not formed. Can be. For example, as shown, when impedance discontinuity occurs in a pair of transmission lines including the third transmission line L3 and the fourth transmission line L4, the third transmission line L3 and the fourth transmission line are shown. A protruding region 118 may be formed in the insulating layer 15 corresponding to L4.

The insulating layer 115 may be formed to have a third thickness d3, and the protruding region 118 may be formed to have a fourth thickness d4 based on the insulating layer 115. Since the impedance of the third and fourth transmission wires L3 and L4 is inversely proportional to the thickness of the insulating layer 115, the insulating layer 115 corresponding to the third and fourth transmission wires L3 and L4 may be formed. The impedance may be reduced by taking the sum of the third thickness d3 of the insulating layer 115 and the fourth thickness d4 of the protruding region 118 to reduce impedance and achieve impedance matching between the receiver and the transmitter. The third thickness d3 may be 15 μm to 25 μm, and the fourth thickness d4 may be 10 μm to 20 μm.

Through the impedance matching, the signal distortion of the transmission line of the differential signal transmission method can be prevented, thereby improving the image quality. In addition, the ground layer can be removed and impedance matching can be performed without additional layers, contributing to the thinning of the printed circuit board.

8 is a view illustrating a method of manufacturing a printed circuit board of the liquid crystal display according to the second embodiment.

Referring to FIG. 8A, in the method of manufacturing a printed circuit board according to the second embodiment, a dielectric layer 113 is formed, and a metal layer 114 is coated on the dielectric layer 113.

Referring to FIG. 8B, in the method of manufacturing a printed circuit board according to the second embodiment, the metal layer 114 is patterned to form first to sixth transmission wirings L1 to L6.

Referring to FIG. 8C, in the method of manufacturing a printed circuit board according to the second embodiment, an insulating material 116 is coated on the entire surface of the dielectric layer 113 on which the first to sixth transmission lines L1 to L6 are formed.

The photoresist 142 is coated on the upper surface of the printed circuit board on which the insulating material 116 is applied, and the mask 119 is positioned on the photoresist 142. The mask 119 may include a light blocking portion 119a and a transmission portion 119b. The light blocking portion 119a may serve to block ultraviolet rays (UV), and the transmission portion 119b may transmit the ultraviolet rays (UV). The light blocking part 119a is positioned to correspond to the third transmission line L3 and the fourth transmission line L4 and irradiates ultraviolet (UV) light. The photoresist 142 irradiated with ultraviolet (UV) is changed in molecular structure by the ultraviolet (UV), and after removing the partial region of the photoresist 142 and the insulating material 116 using a developer after the ultraviolet irradiation A printed circuit board having an insulating layer 115 including a protruding region 118 as shown in FIG. 8D is formed.

In the second embodiment, a mask including a transmissive part and a light blocking part is described as an example, but a halftone mask including a transmissive part, a blocking part, and a semi-transmissive part is a printing having the insulating layer 115 including the protruding area 118. A circuit board can be formed. In this case, the blocking portion is positioned in the region where the protruding region 118 is to be formed, the transflective portion is positioned in the region where the insulating layer 115 except for the protruding region 118 is to be formed, and the insulating layer 115 is removed. The transmission part may be positioned in the area to irradiate ultraviolet rays and form a printed circuit board.

Compared to the first embodiment, the second embodiment can omit the process of applying the silk layer, thereby simplifying the process compared to the first embodiment, thereby reducing the manufacturing cost.

9 illustrates a flexible circuit board of a liquid crystal display according to a third embodiment.

The flexible circuit board of the liquid crystal display according to the third embodiment is the same except that the silk layer is formed on the flexible circuit board as compared with the first embodiment. Therefore, in the description of the third embodiment, detailed description of parts common to those of the first embodiment will be omitted.

Referring to FIG. 9, the flexible circuit board 220 of the liquid crystal display according to the third exemplary embodiment is overlapped between the printed circuit board 210 and the liquid crystal display panel 201. The flexible circuit board 220 and the printed circuit board 210 may be attached by an anisotropic conductive film, and the flexible circuit board 220 and the liquid crystal display panel 201 may be attached by an anisotropic conductive film.

The data driver 221 may be mounted on the flexible circuit board 220. First to eighth transmission lines L11 to L18 connecting the data driver 221 and the printed circuit board may be formed on the flexible circuit board 220.

Although a plurality of transmission wirings are formed on the flexible circuit board 220, the first to eighth transmission wirings L11 to L18 will be described in the drawings. In the first to eighth transmission lines L11 to L18, two wires may be formed in a pair for a differential signal transmission method. In other words, the first and second transmission wirings L11 and L12 are formed in a pair, and the third and fourth transmission wirings L13 and L14 are formed in a pair, and the fifth and sixth transmission wirings are formed. L15 and L16 may be formed in a pair, and the seventh and eighth transmission lines L17 and L18 may be formed in a pair.

The pair of transmission wirings, for example, the first and second transmission wirings L11 and L12 may be formed at regular intervals to cancel the electric field. In addition, a predetermined interval may be formed between each pair of transmission wirings to prevent the influence of signal interference and electric field. In other words, the interval between the pair of first and second transmission lines L11 and L12 is between the second transmission line L12 and the third transmission line L13, which are intervals between the transmission lines included in another adjacent pair. It may be formed narrower than the interval of. The pair of transmission wires may transmit signals in a differential signal transmission method. Since the signal applied from the printed circuit board 210 to the data driver 221 is a digital signal, the digital signal may be transmitted by a differential signal transmission method through the plurality of transmission wires.

The silk layer 217 may be formed on the flexible circuit board 220. The silk layer 217 may be formed in a region corresponding to the transmission wiring formed in pairs. The silk layer 217 may be formed in the upper region of the transmission line pair where impedance is discontinuous. For example, when an impedance discontinuity occurs in a pair of transmission lines including the fifth transmission line L15 and the sixth transmission line L16, the fifth transmission line L15 and the sixth transmission line are shown. The silk layer 217 may be formed in a region corresponding to L16. When impedance discontinuities appear in all of the plurality of transmission lines, a silk layer 217 may be formed to cover the entire surface of the plurality of transmission lines.

Since the flexible circuit board 220 is thinner than the printed circuit board 210, the impedance control effect due to the application of the silk layer 217 is more apparent. Therefore, by applying the silk layer, it is possible to prevent the distortion of the signal to improve the image quality of the liquid crystal display device.

10 is a diagram illustrating a liquid crystal display according to a fourth embodiment.

The liquid crystal display according to the fourth embodiment is the same as the first embodiment except that the silk layer is formed on the array substrate. Therefore, in the description of the fourth embodiment, detailed description of parts common to those of the first embodiment will be omitted.

Referring to FIG. 10, the liquid crystal display according to the fourth exemplary embodiment may include a liquid crystal display panel 301, a printed circuit board 310, and a flexible circuit board 320.

The liquid crystal display panel 301 includes an array substrate 303 on which a thin film transistor is formed and a color filter substrate 305 on which a color filter is formed. The array substrate 303 and the printed circuit board 310 of the liquid crystal display panel 301 may be connected by a plurality of flexible circuit boards 320. A plurality of data drivers 321 may be formed on the plurality of flexible circuit boards 320. The timing controller 311 is formed on the printed circuit board 310, and transmits a control signal to the flexible circuit board 320 through a plurality of transmission wirings L1 to Ln.

The gate driver 330 may be formed on the array substrate 303. The gate driver 330 is formed by a gate in panel method which is directly mounted on the array substrate 303 rather than a flexible printed circuit board or a printed circuit board.

First to fourth connection wires L21 to L24 may be formed on the array substrate 303 to connect the flexible circuit board 310 and the gate driver 330. Although a plurality of connection wires may be formed on the array substrate 303, the first to fourth connection wires L21 to L24 will be described in the drawings. The first to fourth connection wires L21 to L24 may be formed in a pair of two wires for a differential signal transmission method. In other words, the first and second connection lines L21 and L22 may be formed in a pair, and the third and fourth connection lines L23 and L24 may be formed in a pair.

The paired connection wires, for example, the first and second connection wires L21 and L22 may be formed at regular intervals to cancel the electric field. In addition, each connection wiring may be formed to be spaced apart from each other to prevent the influence of signal interference and the electric field. In other words, the distance between the pair of the first and second connection wires L21 and L22 is between the second connection wire L22 and the third connection wire L23, which are distances from the connection wires included in another adjacent pair. It may be formed narrower than the interval of. The pair of connection wires may transmit signals in a differential signal transmission method.

The control signal transmitted from the timing controller 311 to the flexible circuit board 320 includes a gate control signal GDC, a data control signal DDC, and data RGB. The data control signal DDC and the data RGB are transmitted to the data driver 321, and the gate control signal GDC is connected to the gate driver 330 through first to fourth connection wires L21 to L24. Is sent to. Since the gate control signal GDC is a digital signal, the pair of connection wires may transmit the gate control signal GDC in a differential signal transmission method.

The silk layer 317 may be formed on the array substrate 303. The silk layer 317 may be formed in a region corresponding to the connection wiring formed in pairs. The silk layer 317 may be formed in an upper region of the pair of connection wirings whose impedance is discontinuous. For example, when an impedance discontinuity occurs in a pair of connection lines including the third connection line L23 and the fourth connection line L24, the third connection line L23 and the fourth connection line ( The silk layer 317 may be formed in the region corresponding to L24. When impedance discontinuities appear in all of the plurality of connection wires, a silk layer 317 may be formed to cover the entire surface of the plurality of connection wires.

Since a conventional array substrate does not have an impedance adjustable configuration, the impedance may be adjusted using the silk layer 317, and thus, image distortion of the liquid crystal display may be improved by preventing signal distortion.

1,201,301: liquid crystal display panel 10,210,310: printed circuit board
11,311: Timing Controller 13,113: Dielectric Layer
14,114 metal layer 15,115 insulation layer
16: silk material 17,217,317: silk layer
19,119: mask 20,220,320: flexible circuit board
21,221.321 Data Driver 40: Ground Floor
42,142: photoresist 116: insulating material
118: protrusion area 303: array substrate
305: color filter substrate

Claims (17)

A timing controller configured to receive a signal from an external source and generate a control signal; And
A plurality of transmission wirings for transferring the control signal from the timing controller to a gate driver and a data driver,
In the plurality of transmission wires, two transmission wires are formed in pairs to transmit the control signal by a differential signal transmission method, thereby forming a transmission wire group.
Printed circuit board for applying a silk layer on the transmission wiring group of the impedance discontinuity of the transmission wiring group. The method of claim 1,
The silk layer is a printed circuit board that serves to prevent the solder trapped shape in the soldering process. The method of claim 1,
The silk layer is a printed circuit board formed of a material containing an epoxy. The method of claim 1,
The silk layer is applied to the entire area formed with the plurality of transmission wiring. The method of claim 1,
The differential signal transmission method is a low voltage differential signaling (LVDS) method or a reduced swing differential signaling (RSDS) method. A printed circuit board including a timing controller;
A liquid crystal display panel including an array substrate and a color filter substrate;
A flexible circuit board connecting the liquid crystal display panel and the printed circuit board and having a data driver mounted thereon; And
A plurality of transmission wirings for transmitting a control signal from the timing controller to the data driver,
In the plurality of transmission wires, two transmission wires are formed in pairs to transmit the control signal by a differential signal transmission method, thereby forming a transmission wire group.
And a silk layer is coated on the transmission wiring group in which impedance discontinuities appear in the transmission wiring group. The method according to claim 6,
The silk layer is a liquid crystal display device that serves to prevent the solder trapped shape in the soldering process. The method according to claim 6,
Wherein the printed circuit board includes:
A dielectric layer for maintaining the shape of the printed circuit board; And
An insulating layer formed on the dielectric layer to insulate a plurality of transmission wirings from the outside;
The plurality of transmission wires are formed on the dielectric layer,
And the silk layer is formed on the insulating layer. 9. The method of claim 8,
And the silk layer is formed of the same material as the insulating layer. 9. The method of claim 8,
And the silk layer is applied to a region of the transmission wiring group corresponding to the transmission wiring group in which a ground layer is not formed on the rear surface of the dielectric layer. 9. The method of claim 8,
And removing the silk layer in a region where the silk layer is formed, and forming a protruding region protruding from the insulating layer. 9. The method of claim 8,
Wherein the insulating layer has a thickness of 15 μm to 25 μm and the silk layer has a thickness of 10 μm to 20 μm. The method according to claim 6,
And a distance between the respective transmission wiring groups is wider than an interval between the pair of transmission wirings constituting each transmission wiring group. The method according to claim 6,
And the silk layer is formed on a transmission line group formed on the flexible circuit board to connect the printed circuit board and the data driver. The method according to claim 6,
The array substrate,
A gate driver generating a gate signal from the gate control signal;
It includes a plurality of connection wirings for connecting the flexible circuit board and the gate driver,
The plurality of connection wirings form a connection wiring group in which two connection wirings are paired to transmit the gate control signal by a differential signal transmission method.
The silk layer is coated on the connection wiring group in which impedance discontinuity among the connection wiring group. 16. The method of claim 15,
And the gate control signal is transmitted through the flexible circuit board. 16. The method of claim 15,
And a spacing between each of the connection wiring groups is wider than a distance between a pair of connection wirings constituting each connection wiring group.

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