Flexible display device and method for manufacturing the same

Flexible display device and method for manufacturing the same
RE49052

Discussed is a flexible display device to reduce a width of a bezel. The flexible display device includes a substrate being formed of a flexible material, a plurality of gate lines and a plurality of data lines crossing each other, a plurality of pads formed in a pad area of a non-display area, a plurality of links formed in a link area of the non-display area a plurality of insulation films formed over the entire surface of the substrate, and a first bending hole formed in a bending area of the non-display area, the first bending hole passing through at least one of the insulation films disposed under the link, wherein the bending area is bent such that the pads are disposed on the lower surface of the substrate.

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Patent RE49052
Priority May 28 2013
Filed Nov 29 2017
Issued Apr 26 2022
Expiry Dec 19 2033
Inventors Youn, Sang…
Assg.orig LG Display…
Assg.curr LG Display…
Entity Large
Referenced by 1
References 29
Maint.: currently ok

CROSS-REFERENCE TO R…

1. A method for manufacturing a flexible display device comprising:

forming a substrate defined by a display area and a non-display area being an outer region of the display area and including a link area and a pad area, using a flexible material;

forming an anti-etching layer in at least a part including the bending area of the non-display area on the substrate;

forming a buffer film over the surface of the substrate in which the anti-etching layer is formed;

forming a gate insulation film over the surface of the buffer film;

forming gate lines in the display area on the gate insulation film;

forming an interlayer insulation film over the entire surface of the gate insulation film such that the interlayer insulation film covers the gate lines;

forming a first bending hole exposing at least a part of the anti-etching layer, the first bending hole passing through at least one of the buffer film, the gate insulation film and the interlayer insulation film in a bending area, wherein the bending area bends such that the pad area of the non-display area is disposed on the lower surface of the substrate;

forming data lines and a plurality of links, wherein the data lines are formed in the display area on the interlayer insulation film such that the data lines cross the gate lines, and;

forming a plurality of links, wherein the plurality of links are connected to signal lines selected from the gate lines and the data lines in the linking area on the interlayer insulation film;

forming a protective film over the surface of the interlayer insulation film such that the protective film covers the data lines and the links;

forming a plurality of pads connected to the links and connected to an exterior circuit to supply a driving signal to the signal line on the protective film; and

bending the bending area such that the pads are disposed on the back side of the surface of the substrate,

wherein each of the links includes a portion overlapping with the first bending hole in the bending area, and

wherein each of the links directly contacts at least a part of the anti-etching layer exposed through the first bending hole in the bending area.

0. 2. The method according to claim 1, further comprising: forming an anti-etching layer in at least a part including the bending area of the non-display area on the substrate, before formation of the buffer film,

wherein the first bending hole further passes through the buffer film to expose at least a part of the anti-etching layer, during formation of the first bending hole, and

the link directly contacts at least a part of the anti-etching layer exposed through the first bending hole in the bending area, during formation of the link.

3. The method according to claim 2 1, further comprising forming at least one second bending hole passing through the protective film and the anti-etching layer in the periphery of the link in the first bending hole to expose a part of the substrate, after formation of the protective film.

4. The method according to claim 2 1, wherein the anti-etching layer is further formed in the pad area during formation of the anti-etching layer, and

the first bending hole is further formed in the pad area during formation of the first bending hole.

5. The method according to claim 2 1, wherein, during formation of the anti-etching layer, the anti-etching layer is formed using a material having softness higher than the insulation films and having an etch ratio lower than the insulation films upon etching to form the first bending hole.

6. The method according to claim 2 1, wherein, during formation of the anti-etching layer, the anti-etching layer is formed using at least one of ITO, Mo, Ti, Cu, Ag, Au and a-Si.

7. The method according to claim 2 1, wherein the anti-etching layer includes a plurality of anti-etching patterns corresponding to the links, during formation of the anti-etching layer, and

the first bending hole includes a plurality of first bending holes to expose at least a part of the respective anti-etching patterns during formation of the first bending hole, and

the links contact the anti-etching patterns exposed through the first bending holes, respectively, during formation of the data lines and the links.

8. The method according to claim 1, further comprising:

forming an anti-etching layer in the bending area of the non-display area on the substrate, before formation of the buffer film; and

forming a pre-bending hole passing through the buffer film in the bending area such that the pre-bending hole exposes at least a part of the anti-etching layer, after formation of the buffer film.,

wherein the first bending hole passes through the gate insulation film and the interlayer insulation film in the pre-bending hole, in a width smaller than the pre-bending hole to expose the anti-etching layer, during formation of the first bending hole, and

the link each of the links directly contacts at least a part of the anti-etching layer exposed through the pre-bending hole and the first bending hole in the bending area, during formation of the link.

0. 9. The method according to claim 1, wherein a length of the first bending hole in a width direction of the link is larger than a width of the link.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 106 105 and the anti-etching layer 106 in the periphery of the link LK in the first bending hole BH1 to expose a part of the substrate 101.

As a result, when the protective film 105 and the anti-etching layer 106 are removed by formation of the second bending hole BH2 in a portion of the bending area BA, excluding the periphery of the link LK, bending stress factors are further reduced and defects caused by bending stress can thus be further prevented.

Next, the third embodiment of the present invention will be described with reference to FIG. 9.

FIG. 9 is a sectional view illustrating the part IMF of FIG. 4 according to the third embodiment of the present invention.

As shown in FIG. 9, the flexible display device according to the third embodiment further includes a pre-bending hole pre_BH1. The pre-bending hole pre_BH1 is formed after formation of the buffer film 102 and before formation of the active layer 111 to correspond to the bending area BA and to pass through the buffer film 102 in a width greater than the first bending hole BH1. The other portions are the same as that of the first or second embodiment. An overlapping description thereof is thus omitted below.

Forming the pre-bending hole pre_BH1 shown in FIG. 9 results in removing the buffer film 102 in the bending area prior to the formation of the first bending hole BH1. Accordingly, it is not necessary to remove the buffer film 102 anymore in forming the first bending hole BH1, but to remove only the gate insulation film 103 and the interlayer insulation film 104. Meanwhile, the source hole SH and the drain hole DH pass through the gate insulation film 103 and the interlayer insulation film 104, like the first bending hole BH1 of the present embodiment. Damage to the active layer 111 exposed due to the formation of the source hole SH and the drain hole DH caused by over-etching during the formation of the first bending hole BH1 can thus be minimized.

Next, the flexible display device according to the fourth embodiment of the present invention will be described with reference to FIGS. 10 and 11.

FIG. 10 is a plan view illustrating the part I of FIG. 1 according to the fourth embodiment of the present invention in more detail. FIG. 11 is a sectional view illustrating the part V-V′ of FIG. 10.

As shown in FIGS. 10 and 11, the flexible display device of the fourth embodiment is configured to form the first bending hole BH1 and the anti-etching layer 106 further in the pad area PDA as well as the bending area BA. The other portions are the same as those of the first to third embodiments. An overlapping description thereof is thus omitted below.

Next, a method for manufacturing the flexible display device according to the first embodiment of the present invention will be described with reference to FIGS. 12, 13, 14a to 14c, 15a to 15g, and 16a and 16b.

FIG. 12 is a flowchart illustrating a method for manufacturing the flexible display device according to the first embodiment of the present invention. As shown in FIG. 12, the method for manufacturing the flexible display device according to the first embodiment includes: preparing, at step S110, a substrate 101 formed of a flexible material and including a display area AA and a non-display area NA1 which is an outer region of the display area AA and includes a link area LKA and a pad area PDA; forming, at step S120, an anti-etching layer 106 in at least a part of the non-display area NA1 on the substrate 101; forming, at step S130, a buffer film 102 over the entire surface of the substrate 101.

The method further includes: forming, at step S140, (1) gate lines GL and data lines DL on the buffer film 102 in the display area AA; (2) a plurality of insulation films on the entire surface of the buffer film 102; (3) a first bending hole BH1 in the bending area BA of the non-display area NA1; (4) a plurality of pads PD in the pad area FDA of the nondisplay area NA1; and (5) a plurality of links LK in the link area of the non-display area NA1,

At the above step S140, the first bending hole is configured to passes through at least one of a plurality of insulation films in the bending area of the non-display area. The bending area is configured to be bent such that the pad area is disposed on the lower surface of the substrate. The plurality of pads is configured to be connected to an exterior circuit to supply a driving signal to any one signal line of the gate line and the data line. The plurality of links is configured to connect respective pads with the signal lines.

The method further includes: forming, at step S150, a light emitting array including a plurality of light emitting elements EL in respective pixel areas PA; forming, at step S160, a sealing layer 130 in the display area AA. The sealing layer 130 seals the light emitting elements EL such that the sealing layer 130 faces the substrate 101 via the light emitting elements EL; and bending, at step S170, a bending area BA such that the pads PD are disposed on the lower surface of the substrate 101.

FIG. 13 is a flowchart illustrating formation of a cell array, links and pads, as shown in FIG. 13, formation of the gate lines GL and the data lines DL, the insulation films, the first bending hole BH1, the pads PD and the links LK executed at step S140 includes: (1) forming, at step S141, an active layer 111 in a part of each pixel area PA on the buffer film 102; (2) forming, at step S142, a gate insulation film 103 over the entire surface of the buffer film 102; (3) forming, at step S143, gate lines GL and gate electrodes 113 connected thereto on the gate insulation film 103; (4) forming, at step S144, an interlayer insulation film 104 over the entire surface of the gate insulation film 103; (5) forming, at step S145, a source hole SH, a drain hole DH, a link hole LKH and the first bending hole BH1, wherein each of the source hole, the drain hole and the link hole passes through the interlayer insulation film 104 and the gate insulation film 103, and wherein the first bending hole BH1 passes through the interlayer insulation film 104, the gate insulation film 103 and the buffer film 102; (6) forming, at step S146, the data lines DL, the source electrode 114a, the drain electrode 114b and the links LK on the interlayer insulation film 104; (7) forming, at step S147, a protective film 105 over the entire surface of the interlayer insulation film 104; (8) forming, at step S148, a pad hole PDH passing through the protective film 105; and (9) forming at step S149, the pads PD on the protective film 105.

FIG. 14a illustrates a first process of a method for manufacturing the flexible display device. As shown in FIG. 14a, a substrate 101 formed of a flexible material is prepared (S110). For this purpose, a sacrificial substrate (not shown) may be used.

FIG. 14b illustrates a second process of a method for manufacturing the flexible display device. As shown in FIG. 14b, an anti-etching layer 106 is formed in at least a part of the non-display area NA including the bending area BA on the substrate 101 (S120).

The anti-etching layer 106 may be formed in the entirety of the non-display area NA, or only in at least one of selected side area of the non-display area NA, including the later-formed first bending hole (Bill of FIGS. 4 to 6).

The anti-etching layer 106 includes the bending area BA and is thus bent together with the substrate 101. Although the etching process to form the first bending hole BH1 is performed under over-etching conditions, it is necessary to prevent exposure of the substrate during etching and generation of foreign matter caused by the anti-etching layer 106. Accordingly, a material for the anti-etching layer 106 may be selected from materials having a higher softness in other words, lower hardness) and a lower etch ratio than each of inorganic insulating materials for at least one of the later-formed buffer film 102, gate insulation film 103 and interlayer insulation film 104.

For example, a material for the anti-etching layer 106 is selected from ITO, Mo, Ti and a-Si which are advantageous in terms of process cost, easiness and universality.

Furthermore, because the plurality of links (LK of FIGS. 1 and 5) connected to the anti-etching layer 106 through the first bending hole BH1, in a case in which the anti-etching layer 106 is formed of a conductive material, the links LK may be short-circuited through the anti-etching layer 106. To prevent this, the anti-etching layer 106 is provided as a plurality of anti-etching patterns (106a and 106b of FIGS. 4, 6-8 and 10) that correspond to a plurality of links LK and are separated from one another.

FIG. 14c illustrates a third process of a method for manufacturing the flexible display device. As shown in FIG. 14c, a buffer film 102 is formed over the entire surface of the substrate 101 (S130).

FIG. 15a illustrates a fourth process of a method for manufacturing the flexible display device. As shown in FIG. 15a, the active layer 111 is formed on the buffer film 102 (S141), and a gate insulation film 103 covering the active layer 111 is formed over the entire surface of the buffer film 102 (S142). The active layer 111 includes a channel area 111a, and a source region 111b and a drain region 111c disposed at both sides of the channel area 111a.

Then, a gate electrode 113 overlapping at least a part of a channel area of the active layer 111 and gate lines (not shown, but corresponding to GL of FIGS. 1 and 5) electrically connected to the gate electrode 113 are formed on the gate insulation film 103 (S143). Next, the interlayer insulation film 104 covering the gate electrode 113 and the gate lines GL is formed over the entire surface of the gate insulation film 103 (S144).

FIGS. 15b and 15c illustrate fifth and sixth processes of a method for manufacturing the flexible display device. As shown in FIG. 15b, the interlayer insulation film 104 and the gate insulation film 103 are selectively patterned to form a source hole SH, a drain hole DH. Similarly, as shown in FIG. 15c, the interlayer insulation film 104, the gate insulation film 103 and the buffer film 102 are selectively patterned to form a source hole SH, a drain hole DH, a link hole LKH and a first bending hole BH1 (S145).

The source hole SH passes through the interlayer insulation film 104 and the gate insulation film 103 to expose at least a part of the source region 111b.

The drain hole DH passes through the interlayer insulation film 104 and the gate insulation film 103 to expose at least a part of the drain region 111c.

The link hole LKH functions as a contact hole to connect the gate line GL and the links LK disposed in a layer different from the gate line GL and passes through the interlayer insulation film 104 and the gate insulation film 103 to expose at least a part of the gate line GL.

The first bending hole BH1 functions to prevent generation of cracks caused by application of greater bending stress to the buffer film 102, the gate insulation film 103 and the interlayer insulation film 104, as compared to stress applied to the substrate 101, when the bending area BA is bent. The first bending hole BH1 passes through the buffer film 102, the gate insulation film 103 and the interlayer insulation film 104, and exposes at least a part of the anti-etching layer 106 in the bending area BA.

FIGS. 15b and 15c illustrate seventh and eighth processes of a method fur manufacturing the flexible display device. As shown in FIGS. 15d and 15e, the source electrode 114a, the drain electrode 114b, the data line (DL of FIG. 1), and the links LK are formed on the interlayer insulation film 104. The data line DI, is connected to one of the source electrode and the drain electrode. Each of the links LK is connected to one of the gate lines GL and the data lines DL. The links LK are formed to be extended to the pad area PDA.

The source electrode 114a is connected to the source region 111b of the active layer 111 through the source hole SH, and the drain electrode 114b is connected to the drain region 111c of the active layer 111 through the drain hole DH.

Some links LK corresponding to the gate lines GL are connected to the gate line GL, through the link hole LKH, and other links LK corresponding to the data lines DL are configured to be extended from the data line DL.

In addition, the links LK directly contact the anti-etching layer 106 through the first bending hole BH1 in the bending area BA.

When the anti-etching layer 106 is a conductive material, the links LK contact a plurality of anti-etching patterns (corresponding to 106a and 106b of FIG. 3) one-on-one through the first bending holes BH1.

FIG. 15f illustrates a ninth process of a method for manufacturing the flexible display device. As shown in FIG. 15f, a protective film 105 covering the source electrode 114a, the drain electrode 114b, data lines DL, links LK and the first bending hole BH1 is formed over the entire surface of the interlayer insulation film 104 (S147).

FIG. 15g illustrates a tenth process of a method for manufacturing the flexible display device. As shown in FIG. 15g, a pad hole PDH passing through the protective film 105 to expose at least a part of the link LK is formed in at least a part of the pad area PDA (S148) and a plurality of pads PD connected to a plurality of links LK one-on-one are formed on the protective film 105 (S149).

FIG. 16a illustrates an eleventh process of a method for manufacturing the flexible display device. As shown in FIG. 16a, a plurality of light emitting elements ELs is formed on the protective film 105. each of the plurality of light emitting elements ELs includes a first electrode 121, a bank 122, a light emitting layer 123 and a second electrode 124. The plurality of light emitting elements is configured to form a light emitting array corresponding to the display area (S150).

FIG. 16b illustrates a twelfth process of a method for manufacturing the flexible display device. As shown in FIG. 16b, a sealing layer 130 is formed in the display area AA to face the substrate 101 via the light emitting element EL. The sealing layer is formed to seal the light emitting element EL (S160).

Although not illustrated, a method for the flexible display device according to the fourth embodiment of the present invention (corresponding to FIGS. 10 and 11) is the same as in FIG. 14b, except that, during formation of the anti-etching layer 106 (S120), the anti-etching layer 106 is further formed in the pad area PDA as well as the bending area BA. In addition, the method for manufacturing the flexible display device according to the fourth embodiment is the same as in FIG. 15c, except that, during formation of the source hole SH, the drain hole DH, the link hole LKH and the first bending hole BH1 (S145), the first bending hole BH1 is further formed in the pad area PDA as well as in the bending area BA and an overlapping description thereof is thus omitted below.

As shown in FIG. 3, the bending area BA is bent and the pads PD are disposed on the lower surface of the substrate 101 (S170).

Meanwhile, although not illustrated in FIG. 12, FIGS. 14a to 14c, FIGS. 15a to 15g, and FIGS. 16a and 16b in detail, a sacrificial substrate (not shown) may be used during preparation of the substrate 101 (S110). That is, the preparation of the substrate 101 may be carried out by laminating a flexible material on the sacrificial substrate (not shown). In this case, the method for manufacturing the flexible display device further includes removing the sacrificial substrate (not shown) after formation of the sealing layer 130 (S160), and before bending the bending area BA of the substrate 101 (S170).

A method for manufacturing the flexible display device according to the second embodiment will be described with reference to FIG. 17.

FIG. 17 is a flowchart illustrating the method for manufacturing the flexible display device according to the second embodiment.

As shown in FIG. 17, the method for manufacturing the flexible display device according to the second embodiment further forms at least one second bending hole BH2 during formation of the pad hole (S148′). The other portions are the same as the first embodiment described above An overlapping description thereof is thus omitted below.

Referring to FIGS. 7 and 8, the second bending hole BH2 passes through the protective film 105 and the anti-etching layer 106, and exposes a part of the substrate 101 in the periphery of the link LK in the first bending hole BM.

The further addition of the second bending hole BH2 enables further removal of the protective film 105 and the anti-etching layer 106 disposed in the periphery of the link LK in the bending area BA, further reduction of the bending stress factor and improvement in reliability and yield of the flexible display device.

Next, referring to FIGS. 18 and 19, a method for manufacturing the flexible display device according to the third embodiment of the present invention and the flexible display device manufactured by the method will be described.

FIG. 18 is a flowchart illustrating a method for manufacturing the flexible display device according to the third embodiment of the present invention. FIG. 19 is a view illustrating a process for forming the pre-bending hole of FIG. 18.

As shown in FIG. 18, the method for manufacturing the flexible display device according to the third embodiment of the present invention further includes forming the pre-bending hole (pre_BH1) before formation of the active layer (S1400). The other portions are the same as the first embodiment described above. An overlapping description thereof is thus omitted below.

As shown in FIG. 19, after formation of the buffer layer 102 (S130 of FIG. 12) and before formation of the active layer 111 (S141), a pre-bending hole pre_BH1 is formed in the bending area BA (S1400). The pre-bending hole pre_BH1 is configured to pass through the buffer layer 102 such that the pre-bending hole pre_BH1 exposes at least a part of the anti-etching layer 106 (S1400).

When the method further includes the pre-bending hole pre_BH1 (S1400), at the step of forming of the source hole SH, the drain hole DH, the link hole LKH and the first bending hole BH1 (S145), the etching of the buffer film 102 which has been carried out only for formation of the first bending hole BH1 becomes unnecessary, consequently, it is possible to prevent the source hole SH, the drain hole DH, and the link hole LKH from being excessively etched while the buffer film 102 is completely patterned to form the first bending hole BH1. As a result, it is possible to reduce damage to the source region 111b, the drain region 111c and the gate line GL by the source hole SH, the drain hole DH and the link hole LKH, respectively.

The flexible display device according to the embodiments of the present invention can reduce a width of a bezel without reducing a width of the non-display area, since the plurality of pads are disposed on the lower surface of the substrate by bending the bending area. Accordingly, the display devices have improved product values associated with aesthetics and usability.

The flexible display device includes the first bending hole, thus enabling removal of parts of each the buffer film, the gate insulation film and the interlayer insulation film which correspond to the bending area. As a result, it is possible to prevent problems such as application of relatively greater bending stress to the buffer film, the gate insulation film and the interlayer sulation film than bending stress to the substrate, when the bending area is bent, generation of cracks and thus breakage (disconnection) of links (wiring). As a result, it is possible to improve reliability and yield of the display device.

In addition, the flexible display device fluffier includes an anti-etching layer between the substrate and the buffer film in a part of the non-display area, that is, in a region including the first bending hole, thus preventing the substrate from being etched by an etching process to form the first bending hole. As a result, it is possible to prevent permeation of foreign matter causing defects and thereby improve reliability and yield of the display device.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

INVENTORS:

Youn, Sang-Cheon, Jin, Hyoung-Suk, Kang, Chang-Heon, Kwon, Se-Yeoul

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