Display device

A display device including a flexible circuit board including an insulation film, the insulation film including an input pad part and an output pad part on a first side thereof; a printed circuit board including a first pad part, the first pad part being connected to the input pad part; and a display panel including a second pad part, the second pad part being connected to the output pad part, wherein the input pad part includes a plurality of input pads that are arranged in at least two pad columns, and the flexible circuit board includes a plurality of dummy layers aligned with the plurality of input pads on a second side of the insulation film, the second side being an opposite side to the first side.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2015-0024471, filed on Feb. 17, 2015, in the Korean Intellectual Property Office, and entitled: “Display Device,” is incorporated by reference herein in its entirety.

BACKGROUND

Embodiments relate to a display device.

2. Description of the Related Art

A flat panel display (e.g., a liquid crystal display or an organic light emitting diode display) may include a display panel including a plurality of pixels, a flexible circuit board fixed to a pad area of the display panel, and a printed circuit board (PCB) coupled to the flexible circuit board. The flexible circuit board may be configured by a chip on film.

The chip on film is a kind of semiconductor chip package in which a driving chip is mounted on a polymer film engraved with a circuit and may be foldable or rollable due to flexibility of a material. The driving chip may serve as a scan driver or a data driver. A pad part of the PCB may be connected with an input pad part of the flexible circuit board, and the PCB outputs a control signal to the driving chip.

The coupling of the PCB and the flexible circuit board may be performed by disposing an anisotropic conductive film (ACF) and the input pad part of the flexible circuit board on the pad part of the PCB and pressing the input pad part of the flexible circuit board by hot press equipment. Then, conductive balls included in the ACF contact the pad part of the PCB and the input pad of the flexible circuit board to conduct the pad part of the PCB and the input pad of the flexible circuit board.

SUMMARY

Embodiments are directed to a display device.

The embodiments may be realized by providing a display device including a flexible circuit board including an insulation film, the insulation film including an input pad part and an output pad part on a first side thereof; a printed circuit board including a first pad part, the first pad part being connected to the input pad part; and a display panel including a second pad part, the second pad part being connected to the output pad part, wherein the input pad part includes a plurality of input pads that are arranged in at least two pad columns, and the flexible circuit board includes a plurality of dummy layers aligned with the plurality of input pads on a second side of the insulation film, the second side being an opposite side to the first side.

The plurality of dummy layers may overlap with the plurality of input pads, respectively, and may have the same size as the plurality of input pads.

The plurality of dummy layers may be made of metal.

The plurality of dummy layers may be made of a solder resist.

The at least two pad columns may include a first pad column and a second pad column, and the second pad column may be aligned with the first pad column.

The at least two pad columns may include a first pad column and a second pad column, and the second pad column may be offset relative from the first pad column at one side of the first pad column.

In the first pad column, the plurality of input pads may directly contact a corresponding input wiring, and in the second pad column, the plurality of input pads may be connected with the corresponding input wiring through a connection wiring on a second side of the insulation film.

Dummy layers of the plurality of dummy layers that are aligned with the second pad column may be integrally formed with the connection wiring.

The at least two pad columns may include a first pad column and a second pad column, dummy layers of the plurality of dummy layers that are aligned with the first pad column may be covered by a first solder resist layer, and dummy layers of the plurality of dummy layers that are aligned with the second pad column may be covered by a second solder resist layer.

The embodiments may be realized by providing a display device including a flexible circuit board including an insulation film, the insulation film including an input pad part and an output pad part on a first side thereof; a printed circuit board including a first film, a first metal layer, a second film, and a second metal layer sequentially laminated on the first film, the printed circuit board including a first pad part in which a part of the second metal layer is connected to the input pad part; and a display panel including a second pad part, the second pad part being connected to the output pad part, wherein the input pad part includes a plurality of input pads that are arranged in at least two pad columns, and the first metal layer includes a first opening therein, the first opening being aligned with a space between the at least two pad columns.

The first film may include a second opening therein, the second opening being aligned with a space between the at least two pad columns.

The at least two pad columns may include a first pad column and a second pad column, and the second pad column may be aligned with the first pad column.

The at least two pad columns may include a first pad column and a second pad column, and the second pad column may be offset relative to the first pad column at one side of the first pad column.

The least two pad columns may include a first pad column and a second pad column, the flexible circuit board may include a first solder resist layer and a second solder resist layer on a second side of the insulation film, the second side being an opposite side to the first side, and the first solder resist layer and the second solder resist layer may overlie the first pad column and the second pad column.

DETAILED DESCRIPTION

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. Further, in the specification, the word “on” means positioning on or below the object portion, but does not essentially mean positioning on the upper side of the object portion based on a gravity direction.

In addition, unless explicitly described to the contrary, the word “comprise” and “include”, and variations such as “includes,” “comprises,” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

FIG. 1illustrates an exploded perspective view of a display device according to a first exemplary embodiment.FIG. 2illustrates a partial cross-sectional view of an assembled state of the display device illustrated inFIG. 1.

Referring toFIGS. 1 and 2, a display device100of a first exemplary embodiment may include a display panel110, a flexible circuit board120, and a printed circuit board130. The display panel110may be, e.g., any one of a liquid crystal panel, an organic light emitting panel, and an electrophoretic panel. In an implementation, a touch screen panel, a polarization film, and a cover window may be laminated on the display panel110.

The display panel110may include a display area DA and a pad area PA (outside the display area). In the display area DA, a plurality of signal lines including a scan line, a data line, and the like and a plurality of pixels PX connected to the plurality of signal lines may be formed.

In the case of the organic light emitting panel, the plurality of signal lines may include a scan line, a data line, and a driving voltage line. In addition, each of the plurality of pixels PX may include at least two thin film transistors (a switching thin film transistor and a driving thin film transistor), and at least one storage capacitor.

The flexible circuit board120may be configured by a chip on film (COF), e.g., may have a COF structure. For example, the flexible circuit board120may include an insulation film121, a driving chip122mounted on the insulation film121, an input pad part124electrically connected with the driving chip122through an input wiring123, and an output pad part126connected with the driving chip122through an output wiring125.

The insulation film121may be, e.g., a polyimide film. The driving chip122may be mounted on the insulation film121by using, e.g., an anisotropic conductive film, a solder bump, or the like. The input wiring123may connect the input pad part124and an input terminal of the driving chip122. The output wiring125may connect an output terminal of the driving chip122and the output pad part126. In an implementation, the input wiring123and the output wiring125may be covered and protected by a solder resist.

The driving chip122may serve as a scan driver that outputs a scan signal to the scan line of the display panel110or may serve as a data driver that outputs a data signal to the data line of the display panel110. In the flexible circuit board120, the input pad part124, the input wiring123, the driving chip122, the output wiring125, and the output pad part126may be formed on one, e.g., same, side (first side) of the insulation film121.

The printed circuit board130may have a multi-layered film structure. For example, the printed circuit board130may include a first film131, a first metal layer132formed on the first film131, a second film133covering the first metal layer132, and a second metal layer134formed on the second film133.

The first film131and the second film133may be, e.g., polyimide films. A part of the second metal layer134may configure or form a first pad part135that is connected to the input pad part124of the flexible circuit board120. The printed circuit board130may include a connector136to receive an external signal, and electronic devices for signal processing, and may output a control signal to the driving chip122of the flexible circuit board120.

The display panel110may include a second pad part115in the pad area PA. The output pad part126of the flexible circuit board120may be connected to the second pad part115. The second pad part115may be electrically connected to the plurality of signal lines in the display area DA.

The first pad part135of the printed circuit board130may be coupled with the input pad part124of the flexible circuit board120by a first anisotropic conductive film141. The output pad part126of the flexible circuit board120may be coupled with the second pad part115of the display panel110by a second anisotropic conductive film142. Accordingly, a conductive passage connecting the printed circuit board130, the flexible circuit board120, and the display panel110may be completed.

The flexible circuit board120may be curved toward (e.g., bent around) a rear side of the display panel110and thus the printed circuit board130may face the rear side of the display panel110. In this case, a dead space outside the display area DA may be minimized.

As a resolution of the display panel110is higher, a greater number of wires and pads may be included on the flexible circuit board120. In order to dispose a greater number of pads in a limited area, each of the input pad part124of the flexible circuit board120and the first pad part135of the printed circuit board130may be formed by a configuration in which pads in two columns are arranged in a zigzag or offset form.

FIG. 3illustrates a partial plan view of an input pad part of a flexible circuit board in the display device illustrated inFIG. 1.FIG. 4illustrates a partial plan view of an opposite surface of the input pad part illustrated inFIG. 3. For example,FIG. 3illustrates a first side of the insulation film andFIG. 4illustrates a second side of the insulation film which is opposite to the first side.FIG. 5illustrates a cross-sectional view of the flexible circuit board ofFIG. 3taken along line V-V.FIG. 6illustrates a cross-sectional view of the flexible circuit board ofFIG. 3taken along line VI-VI.

Referring toFIGS. 3 to 6, the input pad part124of the flexible circuit board120may include a first pad column151and a second pad column152which include a plurality of input pads124aand124barranged in parallel. The second pad column152may be misaligned or offset from the first pad column151below or spaced apart from the first pad column151. For example, the plurality of input pads124aand124bmay be arranged in a zigzag form.

The plurality of input pads124aof the first pad column151may directly contact the corresponding input wiring123. The plurality of input pads124bof the second pad column152may be electrically connected or in communication with the corresponding input wiring123through a connection wiring127that is on the second side of the insulation film121. The connection wiring127may contact the input wiring123and the input pad124bof the second pad column152through two via holes128.

A plurality of dummy layers160(overlapping or aligned with the plurality of input pads124aand124b) may be formed on the second side of the insulation film121. The dummy layer160may be made of metal and may be the same size as the input pads124aand124b(e.g., the dummy layer160may have the same size and shape as the input pads124aand124b). In an implementation, the dummy layer160overlapping or aligned with the input pad124bof the second pad column152may be integrally formed with the connection wiring127.

A first solder resist layer161may be formed on the plurality of dummy layers160that overlap or are aligned with the first pad column151. A second solder resist layer162may be formed on the plurality of dummy layers160that overlap or are aligned with the second pad column152. The first and second solder resist layers161and162may be spaced apart from each other. A space between the first solder resist layer161and the second solder resist layer162may correspond to a space between the first pad column151and the second pad column152.

The plurality of dummy layers160and the first and second solder resist layers161and162may be formed on the second side of the insulation film121. As a result, in the flexible circuit board120, portions corresponding to the first and second pad columns151and152are higher than a portion corresponding to a space between the first and second pad columns151and152. For example, the portion corresponding to the first and second pad columns151and152and the portion corresponding to the space between the first and second pad columns151and152may have a difference in a height of h (seeFIG. 6).

The difference in the height may help reduce a spring back effect by minimizing deformation of the insulation film121and the first anisotropic conductive film141when the input pad part124of the flexible circuit board120is pressed by a hot pressing apparatus in order to couple the printed circuit board130and the flexible circuit board120with each other.

FIGS. 7A and 7Billustrate partial cross-sectional views of a flexible circuit board and a printed circuit board of the display device ofFIG. 1.

Referring toFIGS. 7A and 7B, the first anisotropic conductive film141and the input pad part124of the flexible circuit board120may be positioned on the first pad part135of the printed circuit board130. The input pad part124may face the first pad part135, and the plurality of dummy layers160overlapping with the plurality of input pads124aand124band the first and second solder resist layers161and162may be formed on the second side of the insulation film121.

When the input pad part124of the flexible circuit board120is pressed by a hot pressing apparatus170, conductive balls143included in the first anisotropic conductive film141may contact the first pad part135of the printed circuit board130and the input pads124aand124bof the flexible circuit board120to electrically connect the first pad part135of the printed circuit board130and the input pads124aand124bof the flexible circuit board120. In this process, the pressing apparatus170may selectively press only a portion corresponding to the first and second pad columns151and152by the plurality of dummy layers160and the first and second solder resist layers161and162.

For example, the plurality of dummy layers160and the first and second solder resist layers161and162may directly transfer heat and pressure of the pressing apparatus170to the first and second pad columns151and152. In contrast, the portion of the flexible circuit board120corresponding to the space between the first and second pad columns151and152may not be pressed by the pressing apparatus170due to the height difference h, and even though the portion may be subject to some heat and/or pressure, a deformation degree due to the pressure may be very small (e.g., as illustrated inFIG. 7B), and may not adversely affect the connection or operation of the components.

Accordingly, the first anisotropic conductive film141and the flexible circuit board120may not be subjected to a spring back effect at the space between the first pad column151and the second pad column152, and the display device100of the first exemplary embodiment may help prevent a lifting defect of the flexible circuit board120.

FIGS. 8A to 8Cillustrate partial cross-sectional views of a flexible circuit board and a printed circuit board of a display device in a Comparative Example. The display device of the Comparative Example may not include the dummy layers of the first exemplary embodiment, and a solder resist layer175may be formed on the second side of the insulation film121corresponding to or overlying the input pad part124.

Referring toFIGS. 8A to 8C, in the display device of the Comparative Example, there may be no difference in height between the portion corresponding to the first and second pad columns151and152and the portion corresponding to the space between the first and second pad columns151and152. Accordingly, when the input pad part124of the flexible circuit board120is pressed by the hot pressing apparatus, the first anisotropic conductive film141and the insulation film121may be concavely pressed in the space between the first and second pad columns151and152.

The first anisotropic conductive film141and the insulation film121(which are concavely pressed) may be subjected to a strong spring back effect after pressing, and a lifting defect upheaving in an opposite direction to a pressing direction may occur. For example, the first pad part135of the printed circuit board130and the input pads124aand124bof the flexible circuit board120may be separated from each other to generate a connection defect.

FIG. 9illustrates a partial plan view of an input pad part of a flexible circuit board in a display device according to a second exemplary embodiment.FIG. 10illustrates a partial plan view of an opposite surface of the input pad part ofFIG. 9. For example,FIG. 9illustrates a first side of the insulation film, andFIG. 10illustrates a second, e.g., opposite, side of the insulation film.

Referring toFIGS. 9 and 10, the input pad part124of the flexible circuit board may include a first pad column151and a second pad column152formed to be parallel or aligned with the first pad column151below or spaced apart from the first pad column151. For example, edges of an input pad124aof the first pad column151may be parallel with each other and may be aligned with edges of an adjacent input pad124bof the second pad column152.

The plurality of input pads124aof the first pad column151may directly contact the corresponding input wiring123. The plurality of input pads124bof the second pad column152may also directly contact the corresponding input wiring123. The input wiring123may be connected with the input pad124bof the second pad column152and may include a curved or bent portion between the first pad column151and the second pad column152.

A plurality of dummy layers160overlapping or aligned with the plurality of input pads124aand124bmay be formed on the second side of the insulation film121. The dummy layer160may be made of metal. A first solder resist layer161may be formed on the plurality of dummy layers160overlapping with the first pad column151, and a second solder resist layer162may be formed on the plurality of dummy layers160overlapping with the second pad column152.

The display device of the second exemplary embodiment may be formed by the same configuration and/or processes as the aforementioned first exemplary embodiment, except that the plurality of input pads124aof the first pad column151and the plurality of input pads124bof the second pad column152may be parallel or aligned with each other.

FIG. 11illustrates a partial cross-sectional view of a flexible circuit board in a display device according to a third exemplary embodiment.

Referring toFIG. 11, in the display device of the third exemplary embodiment, a dummy layer160may be formed of a solder resist. In this case, the plurality of dummy layers160and the first and second solder resist layers161and162may be formed by coating the solder resist on the second side of the insulation film121two times. The display device of the third exemplary embodiment may be formed by the same configuration and/or processes as the aforementioned first exemplary embodiment or the second exemplary embodiment, except that the dummy layer160may be formed of a solder resist.

FIG. 12illustrates a partial cross-sectional view of a flexible circuit board and a printed circuit board in a display device according to a fourth exemplary embodiment.

Referring toFIG. 12, in the display device of the fourth exemplary embodiment, a first metal layer132of the printed circuit board130forms a first opening137corresponding to, underlying, or aligned with a space between the first and second pad columns151and152. For example, the first metal layer132may be patterned or otherwise formed such that a portion thereof is spaced apart from another portion thereof to provide the opening137. The flexible circuit board120may not include a dummy layer of the first exemplary embodiment, and first and second solder resist layers161and162overlapping or aligned with first and second pad columns151and152may be formed on the second side of the insulation film121corresponding to the input pad part124.

The first metal layer132may form the first opening137and, as a result, there may be no portion that firmly supports the first anisotropic conductive film141and the insulation film121from below in the space between the first and second pad columns151and152. Accordingly, when the input pad part124of the flexible circuit board120is pressed by the hot pressing apparatus, the insulation film121and the first anisotropic conductive film141corresponding to or underlying the space between the first and second pad columns151and152may not be strongly pressed. Thus, deformation may be minimized.

As a result, the first anisotropic conductive film141and the flexible circuit board120may not be subjected to a spring back effect at the space between the first pad column151and the second pad column152, and the display device of the fourth exemplary embodiment may help prevent a lifting defect of the flexible circuit board120. The display device of the fourth exemplary embodiment may be formed by the same configuration and/or processes as the aforementioned first exemplary embodiment or second exemplary embodiment except that the dummy layer of the flexible circuit board120may be omitted and the first metal layer132may form the first opening137.

FIG. 13illustrates a partial cross-sectional view of a flexible circuit board and a printed circuit board in a display device according to a fifth exemplary embodiment.

Referring toFIG. 13, the display device of the fifth exemplary embodiment may be formed by the same configuration and/or processes as the aforementioned fourth exemplary embodiment, except that a first film131of the printed circuit board130may form or provide a second opening138corresponding to, aligned with, or underlying a space between the first and second pad columns151and152. In the fifth exemplary embodiment, both the first film131and the first metal layer132of the printed circuit board130together may form openings137and138corresponding to the space between the first and second pad columns151and152.

As a result, a portion supporting the first anisotropic conductive film141and the insulation film121from below may be united with a second film133of the printed circuit board130in the space between the first and second pad columns151and152. Accordingly, when the input pad part124of the flexible circuit board120is pressed by the hot pressing apparatus, a portion corresponding to the space between the first and second pad columns151and152in the insulation film121and the first anisotropic conductive film141may not be almost pressed and thus the deformation may be minimized.

By way of summation and review, as a resolution of the display panel increases, a greater number of wires and pads may be disposed on the flexible circuit board. In order to include a greater number of pads in a limited area, a pad part may have a structure in which pads are arranged in two lines.

In this case, the ACF and the flexible circuit board may be pressed by a step with the pad in a space between a pad in a first column and a pad in a second column to be subjected to a strong spring back effect. The spring back effect may act in an opposite direction to a pressing direction as restoring force. Accordingly, a defect in which a part of the flexible circuit board is lifted may occur, and a connection defect between the PCB and the flexible circuit board could be caused due to the defect.

The embodiments may provide a display device including a flexible circuit board and a printed circuit board.

The embodiments may provide a display device capable of preventing a connection defect between a printed circuit board and a flexible circuit board by suppressing a lifting defect of the flexible circuit board at a coupling portion of the printed circuit board and the flexible circuit board.

According to the exemplary embodiments, when an input pad part of the flexible circuit board is pressed by a hot pressing apparatus, the flexible circuit board may be selectively pressed only at a portion corresponding to first and second pad columns. Therefore, a first anisotropic conductive film and a flexible circuit board may not be subjected to a spring back effect at a space between a first pad column and a second pad column and may help prevent a lifting defect of the flexible circuit board.