Display device and method for manufacturing display device

Abstract

A display device (100) according to the present disclosure comprises: a film substrate (FS); a light-emitting element layer (ED) that is located in a layer above the film substrate (FS) and that includes a plurality of light-emitting elements; an inorganic sealing film (K1) that covers the light-emitting element layer (ED); a plurality of pairs of banks (B1, B2) that are located, in plan view, between the outer periphery of the inorganic sealing film (K1) and the outer periphery of the film substrate (FS) and that face each other so as to be spaced apart; and a filler (FM) that is located, in plan view, between at least one of the pairs of banks (B1, B2) of the plurality of pairs of banks (B1, B2) and that contracts or expands through curing.

Description

Display device and method for manufacturing the same

[0001] The present disclosure relates to a display device and a method for manufacturing a display device.

[0002] Patent Document 1 discloses a configuration in which an organic EL element is formed on a substrate formed by laminating a gas barrier film and a heat-resistant film with a stress relaxation sheet sandwiched between them.

[0003] JP 2015-88246 A

[0004] There is a demand for reducing warpage in display devices.

[0005] The display device according to the present disclosure comprises a film substrate, a light-emitting element layer located above the film substrate and including a plurality of light-emitting elements, an inorganic sealing film covering the light-emitting element layer, multiple pairs of banks located between the outer periphery of the inorganic sealing film and the outer periphery of the film substrate in a planar view and facing each other with a gap between them, and a filler material located between at least one pair of the multiple pairs of banks in a planar view and which shrinks or expands upon hardening.

[0006] A method for manufacturing a display device according to the present disclosure includes the steps of forming or fixing a film substrate above a rigid substrate, forming a light-emitting element layer above the film substrate, the light-emitting element layer including a plurality of light-emitting elements, forming an inorganic sealing film that covers the light-emitting element layer, forming multiple pairs of banks that are positioned between the outer periphery of the inorganic sealing film and the outer periphery of the film substrate in a planar view and that face each other with a gap between them, injecting a filler material that shrinks or expands upon hardening between at least one pair of the multiple pairs of banks, hardening the filler material, and peeling the film substrate from the rigid substrate.

[0007] According to one aspect of the present disclosure, warping of a display device can be reduced.

[0008] FIG. 1 is a plan view showing an example of a configuration of a display device according to an embodiment of the present disclosure; FIG. 2 is a cross-sectional view showing an example of a configuration of a display device according to an embodiment of the present disclosure, corresponding to the cross-sectional view AB of FIG. 1; FIG. 3 is a cross-sectional view showing an example of a manufacturing method of a display device according to an embodiment of the present disclosure; FIG. 4 is a plan view showing an example of a configuration of a display device according to an embodiment of the present disclosure; FIG. 5 is a cross-sectional view showing an example of a manufacturing method of a display device according to an embodiment of the present disclosure; FIG. 6 is a cross-sectional view showing an example of a configuration of a display device according to an embodiment of the present disclosure; FIG. 7 is a cross-sectional view showing another example of a configuration of a display device according to an embodiment of the present disclosure; FIG. 8 is a partial plan view showing another example of a configuration of a display device according to an embodiment of the present disclosure.

[0009] [Embodiment 1] Fig. 1 is a plan view showing an example of the configuration of a display device according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view showing an example of the configuration of a display device according to an embodiment of the present disclosure, corresponding to the cross-sectional view taken along the line AB in Fig. 1 . To facilitate understanding of the invention, a filler material FM is hatched in the plan view. As shown in Figs. 1 and 2, a display device 100 according to the present disclosure includes a film substrate FS, a light-emitting element layer ED located above the film substrate FS and including a plurality of light-emitting elements, an inorganic sealing film K1 covering the light-emitting element layer ED, multiple pairs of banks B1, B2 located between the outer periphery of the inorganic sealing film K1 and the outer periphery of the film substrate FS in a plan view and facing each other with a gap therebetween, and a filler material FM located between at least one pair of the banks B1, B2 in a plan view and contracting or expanding upon curing.

[0010] According to the above configuration, contraction or expansion of the filler FM generates stress that tends to contract or expand the space between at least one pair of banks B1, B2 between which the filler FM is located. By controlling (combining) the positions of the banks B1, B2 into which the filler FM is filled, the amount of filler FM filled at each position, and the amount of contraction or expansion of the filler FM, local stress adjustment can be performed, thereby reducing warping of the film substrate FS. In this disclosure, "plan view" means viewing from the thickness direction of the film substrate FS (the z direction in the figure).

[0011] The filler FM may include a cured shrinkable resin. The cured shrinkable resin may be, for example, an acrylic resin, an epoxy resin, or a silicone resin. The shrinkage rate of the filler FM may be 20% or less, 5% to 15%, or 9% to 12%.

[0012] Contraction of the filler FM generates stress that tends to shrink the space between the banks B1 and B2 that correspond to the filler FM, i.e., stress that tends to curve the film substrate FS convexly downward (from the filler FM toward the film substrate FS) in the direction across the corresponding banks B1 and B2. This stress counters the stress that tends to curve the film substrate FS convexly upward (from the film substrate FS toward the filler FM) in the cross direction, thereby reducing the curvature of the film substrate FS in the cross direction.

[0013] Furthermore, the stress caused by the filler FM can also reduce the curvature of the film substrate FS in a direction approximately parallel to the corresponding banks B1, B2 by curving the film substrate FS in a direction crossing the corresponding banks B1, B2.

[0014] The filler FM may be made of different materials depending on the expected warpage of the film substrate FS. Compared to acrylic resins, epoxy resins tend to have a smaller shrinkage rate. Therefore, for example, to reduce the curvature of the film substrate FS, an acrylic resin can be injected between the banks B1 and B2 where a relatively large shrinkage stress is expected to be required, and an epoxy resin can be injected between the banks B1 and B2 where a relatively small shrinkage stress is expected to be required.

[0015] Additionally / alternatively, the injection amount of the filler FM may be adjusted according to the predicted warpage of the film substrate FS. The greater the injection amount of the filler FM, the greater the stress caused by the filler FM. Additionally / alternatively, the number of injection locations of the filler FM may be adjusted according to the predicted warpage of the film substrate FS. The greater the number of injection locations of the filler FM in a certain positional range, the greater the total stress caused by the filler FM in that positional range.

[0016] When the filler FM is curing expandable, the expansion generates stress that tends to curve the film substrate FS convexly upward in a direction crossing the corresponding banks B1 and B2.

[0017] Each pair of banks B1, B2 may include a first bank B1 extending substantially parallel to the nearest edge of the outer periphery of the film substrate FS, and a second bank B2 located between the first bank B1 and the nearest edge and extending substantially parallel to the nearest edge. The second bank B2 may be located directly opposite the corresponding first bank B1.

[0018] The display device 100 may include an organic sealing film K2 located above the inorganic sealing film K1 and an inorganic sealing film K3 covering the organic sealing film K2. The display device 100 may include a thin-film sealing layer TFE including the inorganic sealing films K1 and K3 and the organic sealing film K2. The thin-film sealing layer TFE reduces the intrusion of oxygen and water into the light-emitting element layer ED, thereby reducing deterioration of the light-emitting element layer ED. Multiple pairs of banks B1 and B2 may be located between the periphery of the thin-film sealing layer TFE and the periphery of the film substrate FS in a planar view. The filler FM may be made of the same material as the organic sealing film K2.

[0019] The display device 100 may include a blocking bank DB for blocking the organic sealing film K2. The blocking bank DB may be made of the same material as the pairs of banks B1 and B2. The blocking bank DB overlaps with the inorganic sealing films K1 and K3 in a plan view and is positioned so as to surround the light-emitting element layer ED.

[0020] The display device 100 may further include a backplane BP located between the film substrate FS and the light-emitting element layer ED. The backplane BP may include a barrier layer, wiring, a semiconductor layer, an interlayer insulating film, a planarization film, etc. The backplane BP may include circuit elements, such as pixel circuits, that control the light-emitting elements included in the light-emitting element layer ED. The light-emitting elements included in the light-emitting element layer ED may be organic light-emitting diodes (OLEDs) or quantum dot light-emitting diodes (QLEDs).

[0021] 3 is a cross-sectional view showing an example of a method for manufacturing a display device according to an embodiment of the present disclosure. As shown in FIG. 3, first, a rigid substrate RP is prepared (step S10), a film substrate FS is formed or fixed above the rigid substrate RP (step S20), and a backplane BP is formed on the film substrate FS (step S30).

[0022] Next, a light-emitting element layer ED including a plurality of light-emitting elements is formed on the backplane BP above the film substrate FS (step S40), and a blocking bank DB is formed so as to surround the light-emitting element layer ED (step S50). A part or the whole of the blocking bank DB may be made of the same material as the components of the light-emitting element layer ED, and may be formed simultaneously with the components of the light-emitting element layer ED.

[0023] Then, multiple pairs of banks B1, B2 facing each other with a gap therebetween are formed above the film substrate FS (step S60). Part or all of each of the multiple pairs of banks B1, B2 may be made of the same material as the components of the light-emitting element layer ED, and may be formed simultaneously with the components of the light-emitting element layer ED. Part or all of step S60 may be performed simultaneously with step S40 and / or step S50.

[0024] Then, a thin-film sealing layer TFE is formed (Step S70). In Step S70, first, an inorganic sealing film K1 is formed to cover the light-emitting element layer ED (Step S72), an organic sealing film K2 is formed on the inorganic sealing film K1 (Step S74), and an inorganic sealing film K3 is formed to cover the organic sealing films K1 and K2 (Step S76). In Step S72, the inorganic sealing film K1 is formed so that multiple pairs of banks B1, B2 are located between the periphery of the inorganic sealing film K1 and the periphery of the film substrate FS in a planar view. In other words, in Step S60, multiple pairs of banks B1, B2 may be formed between the planned periphery line of the inorganic sealing film K1 and the periphery of the film substrate FS.

[0025] Next, a filler material FM, which shrinks or expands upon curing, is injected between at least one pair of banks B1, B2 (step S80), and the filler material FM is cured (step S82). After curing, a protective film PF is attached above the thin-film sealing layer TFE (step S90), and the film substrate FS is peeled off from the rigid substrate RP (step S92). Some or all of the filler material FM may be made of the same material as the organic sealing film K2 and may be formed simultaneously with the organic sealing film K2. In step S80, the filler material FM is injected individually between each pair (or not at all), and the injection amount can be determined individually. Therefore, if warpage of the film substrate FS is expected to be non-uniformly distributed, determining the injection amount for each filler material FM according to this expectation can reduce the non-uniformity of the warpage.

[0026] Then, the peeled film substrate FS is divided along the division line DL together with the backplane BP and the protective film PF (step S100, so-called "dicing"). Note that in step S60, multiple pairs of banks B1, B2 may be formed between the outer periphery of the inorganic sealing film K1 and the division line DL in a plan view. This allows the multiple pairs of banks B1, B2 to be positioned between the outer periphery of the inorganic sealing film K1 and the outer periphery of the divided film substrate FS.

[0027] Comparative Example A display device according to a comparative example was manufactured as follows.

[0028] First, a film substrate was attached to a glass substrate, and a backplane was formed on the film substrate. The backplane was then made up of a base coat layer, a semiconductor layer, an interlayer insulating film, a wiring layer including a gate electrode, an interlayer insulating film, a wiring layer including a source electrode and a drain electrode, an interlayer insulating film, and a third wiring layer. A planarization film was then formed. Silicon nitride was used for each of the interlayer insulating films.

[0029] Next, a light-emitting layer and a thin-film encapsulating layer were formed on the backplane, and a protective film was attached to the thin-film encapsulating layer. Laser light was then irradiated onto the underside of the film substrate to peel the film substrate from the glass substrate. After peeling, the film substrate was cut together with the backplane to obtain a display device according to the comparative example.

[0030] Many of the display devices were warped after cutting, and the rate of appearance defects where the amount of warping exceeded the standard value was high. The amount of warping was measured by placing the display device on a flat surface and measuring the difference in height between the lowest and highest points on the top surface of the display device with no external force being applied.

[0031] It is understood that the occurrence of warpage in display devices is mainly caused by stress in the interlayer insulating film. Therefore, the thickness of the interlayer insulating film was adjusted to reduce warpage, and the display devices were manufactured again, but the appearance defect rate remained high. The interlayer insulating film was adjusted and the manufacturing process was repeated, but the appearance defect rate remained high.

[0032] Example A display device 100 according to an example of the present disclosure was manufactured as follows.

[0033] A glass substrate was used as the rigid substrate RP, and a backplane BP was formed on a film substrate FS, similar to the display device according to the comparative example. Then, a light-emitting element layer ED and multiple pairs of banks B1 and B2 were formed on the backplane BP, and a thin-film sealing layer TFE was formed to cover the light-emitting element layer ED. Then, a filler FM was injected approximately evenly between each of the multiple pairs of banks B1 and B2, a protective film PF was attached, and the glass substrate was peeled off, and the film substrate FS and the laminate thereon were separated.

[0034] Many of the display devices after division in the example were also warped, and the appearance defect rate was high, with the amount of warp exceeding the standard value. Therefore, based on the distribution of warp, the injection position and injection amount of filler FM were adjusted to reduce the warp, and the display devices were manufactured again. As a result, the appearance defect rate was reduced. Thereafter, the injection position and injection amount of filler FM were repeatedly adjusted for further manufacturing, and the appearance defect rate was further reduced.

[0035] Because it can take several days from the start of backplane formation (step S30) to the cutting of the film substrate (step S100), the warpage condition can change depending on the ambient environment during these several days, making it difficult to reduce the appearance defect rate by adjusting the interlayer insulating film. In addition, because the interlayer insulating film is formed over the entire display device using a method such as chemical vapor deposition (CVD), it is difficult to partially correct partial warpage. In contrast, the process from injecting the filler material FM (step S80) to cutting the film substrate (step S100) is often completed within 10 hours, which reduces the change in the warpage condition due to the ambient environment and is therefore considered beneficial for reducing the appearance defect rate. Furthermore, because the filler material FM is individually injected between multiple pairs of banks B1 and B2 using an inkjet method or the like, partial warpage can be partially corrected.

[0036] [Embodiment 2] Figure 4 is a plan view showing an example of the configuration of a display device according to an embodiment of the present disclosure. As shown in Figure 4, the banks B1 and B2 may be arranged in a staggered manner. One first bank B1 may be arranged so that it faces half of one second bank B2 and faces half of another second bank B2. The second banks B2 may be located diagonally opposite the corresponding first bank B1. A filler material FM may be injected between one first bank B1 and two second banks B2. The filler material FM may include a first filler material FM1 and a second filler material FM2 that is different in material and / or injection amount from the first filler material MF1.

[0037] The configuration according to the second embodiment can also reduce warpage of the film substrate FS, similar to the configuration according to the first embodiment described above.

[0038] [Embodiment 3] Figure 5 is a cross-sectional view showing an example of the configuration of a display device according to an embodiment of the present disclosure. As shown in Figure 5, the display device 100 according to the present disclosure may have a recess RS between at least one pair of banks B1, B2 among multiple pairs of banks B1, B2 in a plan view. According to this configuration, the filler material FM injected into the recess RS is located between the corresponding pair of banks B1, B2 in a plan view (as viewed from the z direction in the figure). When the display device 100 is viewed in a plan view, the length of the banks B1, B2 and the length of the recess RS may be the same, or the length of the recess RS may be shorter than the length of the banks B1, B2. In other words, the recess RS may be formed in a portion of the region between the banks B1, B2.

[0039] By forming the recesses RS in this manner, the maximum volume of the filler material FM that can be injected between the banks B1 and B2 increases by the volume of the recesses RS. The larger the volume of the filler material FM, the greater the stress caused by the filler material FM. Therefore, greater stress can be generated, and warping of the film substrate RS can be further reduced. The depth of the recesses RS is preferably 5 μm or more, and more preferably 10 μm or more. A recess RS may be provided between each of the multiple pairs of banks B1 and B2.

[0040] When the display device 100 further includes a backplane BP located between the film substrate FS and the light-emitting element layer ED, a recess RS may be provided in the backplane BP, and the recess RS may penetrate the backplane BP. The recess RS may also be formed in the film substrate FS.

[0041] (Manufacturing Method) FIG. 6 is a cross-sectional view showing an example of a manufacturing method for a display device according to an embodiment of the present disclosure. As shown in FIG. 6 , after forming a backplane BP above a film substrate FS (step S30), a recess RS may be formed in the backplane BP between at least one pair of banks B1, B2 among multiple pairs of banks B1, B2 (step S110). In step S70, multiple pairs of banks B1, B2 are formed above the backplane BP. The recess RS may be formed simultaneously with the formation of the backplane BP (step S30). Here, the recess RS may also be formed in the film substrate FS so as not to penetrate the film substrate FS. The step of forming the recess RS may involve forming a through-hole in the backplane PB and forming a recess in the film substrate FS that communicates with the through-hole. In the injection of the filler material FM (step S80), the filler material FM injected between the pair of banks B1, B2 flows into the recess RS.

[0042] [Embodiment 4] Figure 7 is a cross-sectional view showing an example of the configuration of a display device according to an embodiment of the present disclosure. As shown in Figure 7, an inorganic bonding film G1 may be provided that covers the opposing side surfaces C1, C2 of at least one pair of banks B1, B2 among multiple pairs of banks B1, B2 and at least a portion of a region C3 located between the at least one pair of banks B1, B2. The inorganic bonding film G1 can improve the bonding strength between the filler material FM and the banks B1, B2. The bonding strength between the filler material FM and the banks B1, B2 is preferably greater than the contraction stress acting between the opposing side surfaces C1, C2 of the banks B1, B2 due to the filler material FM.

[0043] The inorganic bonding film G1 may be made of the same material as either one of the inorganic sealing films K1 and K3, and preferably may be made of the same material as the inorganic sealing film K1 located below the organic sealing film K2. The inorganic bonding film G1 may be formed simultaneously with the inorganic sealing film K1. The inorganic bonding film G1 may be formed in an island shape in a plan view so as to correspond to each of the pairs of banks B1 and B2.

[0044] 8 is a cross-sectional view showing another example of the configuration of a display device according to an embodiment of the present disclosure. As shown in FIG. 8 , this embodiment can be combined with the above-described embodiment 2. The display device 100 according to the present disclosure may have a recess RS, and the region C3 located between the banks B1 and B2 may include the inner surface of the recess RS. The inorganic bonding film G1 covers the opposing side surfaces C1 and C2 of the corresponding pair of banks B1 and B2 and at least a portion of the inner surface of the recess RS located between the corresponding pair of banks B1 and B2.

[0045] In this case, the inorganic bonding film G1 can improve the bonding strength between the filler FM and the banks B1, B2 and / or the bonding strength between the filler FM and the recess RS. The bonding strength between the filler FM and the backplane BP may be greater than the contraction stress acting between the opposing inner wall surfaces of the recess RS due to the filler FM.

[0046] [Embodiment 5] Figure 9 is a plan view showing an example of the configuration of a display device according to an embodiment of the present disclosure. As shown in Figure 9, at least one pair of banks B1, B2 among multiple pairs of banks B1, B2 may form a surrounding structure BS in plan view together with additional banks B3, B4. The filler material FM is less likely to overflow outside the surrounding structure BS. The surrounding structure BS may be polygonal, square, or rectangular in plan view.

[0047] Two or more pairs of banks B1, B2 among the multiple pairs of banks B1, B2 may each constitute a surrounding structure BS. A plurality of surrounding structures BS may exist between the outer periphery of the inorganic sealing film K1 and the outer periphery of the film substrate FS. At least some of the multiple surrounding structures may form a row.

[0048] 10 is a partial plan view showing another example of the configuration of a display device according to an embodiment of the present disclosure, as shown in FIG. 10, at least some of the multiple surrounding structures BS may be arranged in a staggered manner.

[0049] This fifth embodiment can be combined with the third and fourth embodiments. For example, at least one surrounding structure BS may surround the recess RS in a plan view. For example, at least a portion of the opposing side surfaces of the at least one surrounding structure BS may be covered with the inorganic bonding film G1. For example, at least one surrounding structure BS may surround the recess RS in a plan view, and at least a portion of the opposing side surfaces of the surrounding structure and the inner surface of the recess RS may be covered with the inorganic bonding film G1.

[0050] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0051] 100 Display device B1, B2 Bank BP Backplane BS Surrounding structure C1, C2 Opposing side surfaces C3 Area DL Dividing line ED Light emitting element layer FM Filler FS Film substrate G1 Inorganic bonding film K1 Inorganic sealing film RP Rigid substrate RS Recess

Claims

1. A display device comprising: a film substrate; a light-emitting element layer located above the film substrate and including a plurality of light-emitting elements; an inorganic sealing film covering the light-emitting element layer; a plurality of pairs of banks located between the outer periphery of the inorganic sealing film and the outer periphery of the film substrate in a planar view and facing each other with a gap between them; and a filler material located between at least one pair of the plurality of pairs of banks in a planar view, which shrinks or expands upon hardening.

2. The display device according to claim 1, further comprising a recess between at least one pair of said banks among said plurality of pairs of banks.

3. The display device according to claim 1 or 2, wherein the filler material includes a hardening shrinkable resin.

4. The display device according to claim 3, wherein the hardened shrinkable resin is an acrylic resin, an epoxy resin, or a silicone resin.

5. The display device according to claim 3 or 4, wherein the shrinkage rate of the filler is 5.0% or more and 15% or less.

6. The display device according to any one of claims 1 to 5, further comprising an inorganic bonding film made of the same material as the inorganic sealing film, covering the opposing side surfaces of at least one pair of banks among the plurality of pairs of banks and at least a portion of the area located between the at least one pair of banks.

7. The display device according to claim 1, wherein at least one pair of the banks among the plurality of pairs of banks constitutes a surrounding structure in a plan view.

8. The display device according to claim 7, wherein a plurality of the surrounding structures are present between the outer periphery of the inorganic sealing film and the outer periphery of the film substrate.

9. The display device according to claim 8, wherein at least a portion of the plurality of surrounding structures are arranged in a row.

10. The display device according to claim 9, wherein a plurality of rows of the surrounding structures are arranged.

11. The display device according to any one of claims 8 to 10, wherein at least some of the surrounding structures are arranged in a staggered manner.

12. The display device according to claim 2, further comprising a backplane located between said film substrate and said light emitting element layer, said recess penetrating said backplane.

13. A method for manufacturing a display device, comprising the steps of: forming or fixing a film substrate above a rigid substrate; forming a light emitting element layer above the film substrate, the light emitting element layer including a plurality of light emitting elements; forming a plurality of pairs of banks facing each other with a gap therebetween, above the film substrate; forming an inorganic sealing film covering the light emitting element layer such that the plurality of pairs of banks are located between the outer periphery of the inorganic sealing film and the outer periphery of the film substrate in a planar view; injecting a filler material that shrinks or expands upon hardening between at least one pair of the plurality of pairs of banks; hardening the filler material; and peeling the film substrate from the rigid substrate.

14. The method for manufacturing a display device according to claim 13, further comprising a step of dividing the film substrate along a dividing line, and forming the plurality of pairs of banks between an outer periphery of the inorganic sealing film and the dividing line in a plan view.

15. A method for manufacturing a display device as described in claim 13 or 14, further comprising the steps of: forming a backplane above the film substrate; and forming a recess in the backplane between at least one pair of banks among the plurality of pairs of banks.

16. The method for manufacturing a display device according to claim 15, wherein the step of forming the recess comprises forming a through hole in the backplane, and forming a recess in the film substrate that communicates with the through hole.

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