KR20070035302A - Flexible printed circuit board and liquid crystal display comprising the same - Google Patents

Abstract

Provided are a flexible printed circuit board having a structure in which defect detection is easy, and a liquid crystal display including the same. The flexible printed circuit board is formed on at least one surface of the base material, at least one surface of the base material to transmit an electrical signal, and is formed on both sides of the base material, and electrically connected to the wiring pattern, and electrically connected to the liquid crystal panel and the external control circuit, respectively. And a marker formed at each end of each of the connection pads and the arrangement of the connection pads to be exposure indicators of the connection pads.

LCDs, flexible printed circuit boards, markers, coverlays

Description

Flexible printed circuit board and liquid crystal display comprising the same

1 is a perspective view of a flexible printed circuit board according to an embodiment of the present invention.

2 is a cross-sectional view of a flexible printed circuit board according to an embodiment of the present invention.

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

4 is a cross-sectional view of a liquid crystal panel included in a liquid crystal display according to an exemplary embodiment of the present invention.

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

1: flexible printed circuit board 2: liquid crystal panel

3: liquid crystal display device 56, 57: connection pad

58, 59: marker

The present invention relates to a flexible printed circuit board and a liquid crystal display including the same, and more particularly, to a flexible printed circuit board having a structure for easily detecting defects and a liquid crystal display including the same.

Printed circuit boards, which are one of the main materials used in the manufacture of various semiconductor devices, such as ICs (Intergrated Circuits) and memories of liquid crystal displays, are used in the form of film, tape, etc. according to the trend of miniaturization and light weight of semiconductor devices. Flexible Printed Circuit Boards (FPCBs) are often used.

Flexible printed circuit boards form wiring patterns and terminals on the substrate through exposure, development, and etching processes, and coverlays are formed on the circuit patterns to protect and insulate the exposed surfaces of the wiring patterns and terminals. Is formed.

The flexible printed circuit board is connected to the liquid crystal panel of the liquid crystal display device, and at this time, a part of the coverlay formed on the terminal for connection with the liquid crystal panel of the flexible printed circuit board is removed.

Regarding coverlay removal, an optical inspection system was conventionally used to check whether the coverlay was removed as designed. That is, the image data of the flexible printed circuit board from which the coverlay as the test object was partially removed was obtained, and the result was determined as compared with the standard defined as good quality by an image processing apparatus and a computer.

The optical inspection system acquires an image through transmitted light or reflected light. If the brightness gradation of the defective part is higher or lower than the set threshold, respectively, it is determined to be defective. It is difficult to avoid overdetection by such means.

In addition, the inspection related to the degree of coverlay removal was not performed on the entire flexible printed circuit board, but was randomly selected and there was a concern that the process of manufacturing the liquid crystal display may be degraded by performing a separate inspection. .

An object of the present invention is to provide a flexible printed circuit board having a structure that is easy to detect defects.

Another object of the present invention is to provide a liquid crystal display device including the flexible printed circuit board 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 board according to an embodiment of the present invention for achieving the technical problem is formed on at least one surface of the base material, a wiring pattern for transmitting an electrical signal, formed on both sides of the base material, respectively, A connection pad electrically connected to the pattern and electrically connected to the liquid crystal panel and the external control circuit, respectively, and formed at both ends of the arrangement of the connection pads, respectively, to be an indicator of exposure of the connection pad.

According to another aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal panel and a base member including a second substrate coupled with a liquid crystal between a first substrate and the first substrate. A wiring pattern formed on at least one surface of the base material to transmit an electrical signal, each connection pad being formed on both sides of the base material and electrically connected to the wiring pattern and electrically connected to the liquid crystal panel and the external control circuit, respectively; And a flexible printed circuit board formed at each end of the arrangement of the connection pads and including a marker that is an exposure index of the connection pads.

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 flexible printed circuit board 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 and a cross-sectional view of a flexible printed circuit board according to an embodiment of the present invention.

1 and 2, reference numeral 1 denotes a flexible printed circuit board according to an embodiment of the present invention. The flexible printed circuit board 1 is a printed circuit board developed to cope with the trend of miniaturization and complexity of electronic products, and has a high flex resistance.

The flexible printed circuit board 1 has a single-sided structure, a double-sided structure, and a double-sided exposed structure, and serves as an interface while being used for signal connection where a continuous repetitive motion of the bent portion is required. This flexible printed circuit board 1 includes various electronic components 34 and an IC package 36. The IC package 36 may be configured by, for example, a ball grid array (BGA) or a chip sized package (CSP), but is not limited thereto.

The flexible printed circuit board 1 is formed by forming various film elements on the base material 37 made of flexible plastic. Specifically, the wiring pattern 38a and the terminal 39 are formed of copper (Cu), for example, on the mounting side surface of the base material 37 formed of polyimide.

Moreover, the connection pad 56 is formed in the liquid crystal panel 2 side, and the connection pad 57 is formed in the opposite side. The connection pad 57 is connected to an external control circuit, for example, a control circuit included in an electronic device such as a cellular phone or a portable information terminal. When a signal is supplied from the external control circuit to the flexible printed circuit board 1 via the connection pads 57, the electronic component 34 and the IC package 36 exhibit a predetermined function, and therefore the connection pads 56 Predetermined signals are supplied to the driving ICs (22a, 22b, 22c in Fig. 3) through which the display by the liquid crystal panel (2 in Fig. 3) is performed.

At both ends of the arrangement of the connection pads 56 and 57, markers makers 58 and 59 as indices for exposing the connection pads 56 and 57 are formed, respectively.

In order for the connection pad of the flexible printed circuit board to be connected to the liquid crystal panel and the external control circuit, respectively, the coverlay formed on the connection pad must be removed. Conventionally, the coverlays formed on the connection pads were removed to expose the connection pads, and an optical inspection system was used to check whether the coverlays were removed as designed. This not only increases the defective rate of the flexible printed circuit board, but also requires a separate inspection process, thereby prolonging the time of the manufacturing process of the liquid crystal display, thereby lowering the manufacturing efficiency of the liquid crystal display.

Accordingly, the flexible printed circuit board 1 according to the embodiment of the present invention includes the markers 58 and 59 at both ends of the arrangement of the connection pads 56 and 57 as described above, respectively. If the coverlay is removed so that about half of the cover) is exposed, it has a structure that can determine the good flexible printed circuit board 1 without any additional inspection.

The markers 58 and 59 may be made of substantially the same material as that of the wiring pattern 38a and the terminal 39, for example, copper, and the shape thereof may be circular, elliptical, square, triangular, or the like. It is not limited and may be formed in various shapes.

In addition, a resist 41 is applied around the terminal 39 formed on the mounting side surface of the base material 37. The coverlay 42a is formed in the area | regions other than the area | region which apply | coated the resist 41 with polyimide etc., for example.

Moreover, the wiring pattern 38b is formed on the back surface side surface of the base material 37, for example by copper, and the coverlay 42b is formed by the polyimide on the whole front surface, for example. ), And the reinforcement film 43 is formed at least in a region corresponding to the IC package 36 by, for example, polyimide.

The resist 41 is provided such that the terminal 39 is exposed to the outside in the region in which the IC package 36 and the electronic component 34 are mounted. The coverlay 42a is formed on the entire surface of the flexible printed circuit board 1 other than the region where the resist 41 is provided. In addition, the coverlay 42a and the resist 41 are not formed in the connection part with a liquid crystal panel, or the connection part with a connector.

In addition, a portion 38bb of the wiring pattern 38b provided on the rear surface side of the flexible printed circuit 1 corresponding to the rear surface of the IC package 36 is formed to have a large area so as to include the entire IC package 36. have.

The copper film portion 38bb functions as a characteristic holding member for maintaining the characteristics of the IC package 36 in a steady state, and specifically has the following functions. Copper has a higher thermal conductivity than the polyimide forming the base material 37, and therefore the copper film portion 38bb dissipates heat generated in the IC package 36 to the outside. In addition, since copper has light shielding properties, the copper film portion 38bb prevents the IC package 36 from being exposed to light from the back surface side.

In addition, since the copper film portion 38bb is formed to be wider than the IC package 36, the copper film portion 38bb prevents the flexible printed circuit board 1 from bending in the region corresponding to the IC package 36. External forces such as shearing force and bending force are prevented from being applied to the package 36. Furthermore, the reinforcement film 43 provided on the back surface of the flexible printed circuit board 1 corresponding to the region where the resist 41 is formed also prevents the external force from acting on the IC package 36. Moreover, the thickness of the copper film part 38bb is set to 30 micrometers or less, for example.

The wiring pattern 38a on the front side and the wiring pattern 38b on the back side are electrically connected to each other by the through hole 44 passing through the base material 37. Thereby, complex circuits can be configured by utilizing both front and back sides of the flexible printed circuit board 1. In particular, the through hole 44 formed in the copper film portion 38bb located on the rear surface of the IC package 36 further increases the function of the copper film portion 38bb to dissipate heat generated by the IC package 36 to the outside. . Reference numeral 48 denotes soldering.

Hereinafter, a liquid crystal display including a flexible printed circuit board according to an exemplary embodiment of the present invention will be described with reference to FIGS. 3 and 4. 3 is a perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of the liquid crystal panel included in the liquid crystal display according to the exemplary embodiment of the present invention.

As shown in FIG. 3 and FIG. 4, the liquid crystal display device 3 has a liquid crystal panel 2 and a flexible printed circuit board 1. The flexible printed circuit board 1 can use the flexible printed circuit board of the structure mentioned above. In addition, when using a backlight unit other than external light, such as sunlight and room light, the liquid crystal display device 3 has the backlight unit 8. In this specification, an image is displayed on the upper surface of the liquid crystal panel 2, and thus the backlight unit 8 functions as a backlight for supplying light from the opposite side of the observation side.

As the liquid crystal panel 2, a liquid crystal panel of any system can be adopted. For example, a simple matrix liquid crystal panel without a switching element, an active matrix liquid crystal panel using a two-terminal switching element such as a thin film diode (TFD), a thin film transistor (TFT), or the like An active matrix liquid crystal panel or the like using a three-terminal switching element can be employed.

The liquid crystal panel 2 has a first substrate 4a and a second substrate 4b opposite thereto. On one surface of these board | substrates 4a and 4b, the sealing material 6 is formed in frame shape along the outer periphery of the liquid crystal panel 2 by printing etc. And the 1st board | substrate 4a and the 2nd board | substrate 4b are bonded by this sealing material 6.

As shown in FIG. 3, when the 1st board | substrate 4a and the 2nd board | substrate 4b are bonded by the sealing material 6, the clearance gap of predetermined height, ie, a cell gap, is formed between those board | substrates, and between them. The liquid crystal 9 is located. The cell gap is usually maintained in dimensions by a plurality of spherical spacers 11 or column spacers (not shown) dispersed on the surface of the first substrate 4a or the second substrate 4b. .

The 1st board | substrate 4a has the base material 12a formed with glass, plastic, etc., and is semi-transmissive by aluminum (Al), for example on the surface of the liquid crystal 9 side of this base material 12a. The reflective film 13 is formed. The transflective film 13 is formed in a state in which a plurality of openings 14 for light transmissive are arranged in a matrix shape corresponding to display dots which are the minimum units of display. These openings 14 can be formed by, for example, photolithography processing and etching.

On the semi-transmissive reflective film 13, the insulating film 16 is formed by a well-known film formation method, for example, spin coating. On the insulating film 16, for example, a first electrode 17a formed by photolithography processing using, for example, ITO (Indium Tin Oxide) is formed. As shown in FIG. 3, the 1st electrode 17a is formed in stripe shape as a whole as seen from the arrow D direction of FIG. 3 by arranging a some linear electrode in parallel. In addition, in FIG. 1, although the space | interval of each linear electrode is drawn wider than actually in order to show the arrangement state of the 1st electrode 17a easily, in practice, the 1st electrode 17a is narrower at a narrower space | interval. A plurality is formed on the substrate 12a.

On the first electrode 17a, the alignment film 18a is formed as a film having a uniform thickness by, for example, printing using polyimide as a material. The alignment film 18a is subjected to an alignment treatment, for example, a rubbing treatment, to determine the alignment of the liquid crystal 9 on the substrate 4a side. In addition, the polarizing plate 19a is attached to the surface of the outer side of the base material 12a by adhesion, for example. Moreover, the retardation plate is provided between the polarizing plate 19a and the base material 12a as needed.

The 2nd board | substrate 4b which opposes the 1st board | substrate 4a has the base material 12b formed with glass, a plastics, etc., and pigment dispersion is carried out on the surface of the liquid crystal 9 side of this base material 12a, for example. The color filter 21 is formed by the method, the inkjet method, or the like. This color filter 21 is formed by arranging three primary colors of red, green and blue in a predetermined pattern, for example, a stripe arrangement, a delta arrangement, and a mosaic arrangement, by looking at three primary colors of the arrow D direction. One optical element in the color filter 21 is disposed corresponding to one of the display dots which is the minimum unit for displaying an image. Then, three light elements of red, green, and blue are combined into one unit to form one pixel.

In addition, on the color filter 21, the 2nd electrode 17b is formed, for example by photolithography process using ITO as a material. As shown in FIG. 1, the second electrode 17b extends in the direction orthogonal to the first electrode 17a.

By arranging a plurality of linear electrodes in parallel with each other, they are formed in a stripe shape as a whole when viewed from the arrow D direction in FIG. 3. In addition, in FIG. 3, although the space | interval of each linear electrode is drawn wider than actually in order to show the arrangement | positioning state of the 2nd electrode 17b easily, in reality, the 2nd electrode 17b is a narrower space | interval. A plurality is formed on the substrate 12b.

On the second electrode 17b, an alignment film 18b is formed as a film having a uniform thickness, for example, by using polyimide as a material, for example, by printing. And this orientation film 18b is subjected to an alignment process, for example, a rubbing process, and the orientation of the board | substrate 4b side of the liquid crystal 9 is determined. Moreover, the polarizing plate 19b is attached to the surface of the outer side of the base material 12b by adhesion, for example. At this time, the transmission axis of the polarizing plate 19b is set at an angle different from that of the polarizing plate 19a on the side of the first substrate 4a.

2, the 1st board | substrate 4a has the part 4c extended to the outer side of the 2nd board | substrate 4b, and the drive ICs 22a, 22b, 22c on this expansion part 4c, For example, it is mounted using an anisotropic conductive film (ACF). That is, in the present specification, although a driving method of the COG method in which the driving IC is mounted directly on the substrate of the liquid crystal panel is adopted, the present invention is not limited thereto.

The input terminals of these IC chips are connected to an external connection pad 23 formed at the end of the expansion portion 4c of the first substrate 4a.

The output terminal of the driver IC 22b located in the center of the expansion portion 4c is directly connected to the first electrode 17a formed on the first substrate 4a. As a result, the driving IC 22b drives the first electrode 17a. As shown in FIG. 3, in the sealing material 6, a plurality of spherical or cylindrical shot bars 24 are included in a dispersed state. In FIG. 2, the driving ICs 22a and 22c mounted in both regions of the expansion portion 4c are connected to the second electrode 17b formed on the second substrate 4b via the shot bar 24. . As a result, the driving ICs 22a and 22c drive the second electrode 17b.

In FIG. 2, the backlight unit 8 includes a light guide plate 26 formed of plastic or the like and an LED (Light Emitting Diode) 27 as a light emitting source disposed to face the light receiving surface 26a of the light guide plate 26. Has As shown in FIG. 4, the LED 27 is supported by the LED substrate 28 and disposed at a predetermined position. In addition, the diffusion sheet 29 is attached to the surface of the light guide plate 26 on the liquid crystal panel 2 side, that is, the light exit surface 26b by adhesion, for example. In addition, the reflection sheet 31 is attached to the surface on the opposite side to the liquid crystal panel 2 of the light guide plate 26 by adhesion, for example. In addition, the whole backlight unit 8 is attached to the liquid crystal panel 2 via the buffer member 32.

Since the liquid crystal panel 2 is comprised as mentioned above, when the light outside the 2nd board | substrate 4b, ie, the observation side, is strong, the light passes through the 2nd board | substrate 4b, and the liquid crystal 9 ), And is reflected by the transflective film 13 and supplied to the liquid crystal 9 again.

On the other hand, the driving ICs 22a, 22b, and 22c control the voltage applied between the first electrode 17a and the second electrode 17b for each display dot to control the orientation of the liquid crystal 9 for each display dot. . Light reflected from the semi-transmissive reflective film 13 and supplied to the layer of the liquid crystal 9 is modulated according to the orientation of the liquid crystal 9, and the modulated light selectively passes through the polarizing plate 19b to the observation side. The desired image is displayed. In this embodiment, since the color filter 21 is provided on the optical path, the displayed image is a color. In this way, reflective display is performed.

On the other hand, when the light on the observation side is weak, the LED 27 is turned on. At this time, the point or linear light emitted from the LED 27 is introduced into the light guide plate 26 from the light intake surface 26a of the light guide plate 26, and then propagates inside the light guide plate 26, It exits from the light exit surface 26b to the outside in planar shape. This light passes through the first substrate 4a and passes through the opening 14 provided in the transflective film 13, and is supplied to the layer of the liquid crystal 9. This light is modulated according to the orientation of the liquid crystal 9 and displayed as an image on the outside is the same as in the case of the reflection type. In this way, transmissive display is performed.

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.

As described above, the flexible printed circuit board according to the exemplary embodiment of the present invention includes a marker, thereby not only detecting defects of the flexible printed circuit board without performing a separate inspection with respect to the extent of removing the coverlay on the connection pad. The defect rate of the flexible printed circuit board is lowered, which in turn improves the manufacturing process efficiency of the liquid crystal display device.

Claims (6)

Base material; A wiring pattern formed on at least one surface of the base material to transmit an electrical signal; Connection pads formed on both sides of the base material, the connection pads electrically connected to the wiring pattern, and electrically connected to the liquid crystal panel and the external control circuit, respectively; And A flexible printed circuit board comprising markers respectively formed at both ends of the arrangement of the connection pads to serve as an exposure index of the connection pads. The method of claim 1, And a coverlay that exposes at least a portion of the marker. The method of claim 1, And the marker comprises copper. A liquid crystal panel comprising a second substrate bonded to a first substrate through a liquid crystal between the first substrate and the first substrate; And A base material, a wiring pattern formed on at least one surface of the base material to transmit an electrical signal, respectively formed on both sides of the base material, electrically connected to the wiring pattern, and electrically connected to a liquid crystal panel and an external control circuit, respectively And a marker that is formed at both ends of the pad and the array of the connection pads, respectively, and serves as an exposure index of the connection pads. The method of claim 4, wherein And a coverlay for exposing at least a portion of the marker. The method of claim 4, wherein And the marker comprises copper.

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