Glass substrate and method for manufacturing the same
By introducing discontinuous structures and polymer filling on the glass bearing substrate of the OLED display, forming a spherical or hexagonal arrangement of recesses, the problems of fragility and production complexity are solved, flexibility and mechanical stability are improved, and service life is extended And reduces manufacturing costs.
Patent Information
- Application Number
- CN202180046711.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-07-28
- Filing Date
- 2021-05-20
- Publication Date
- 2024-12-10
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In the prior art, the glass bearing substrate of flexible OLED displays is fragile and the production process is complex, resulting in high manufacturing costs and waste, and the OLED material is sensitive to oxygen and moisture, resulting in short service life.
Using a substrate made of glass, with substantially stable sections and flexible sections, by introducing discontinuous structures and polymer fillings on the substrate, a spherical or hexagonal arrangement of recesses is formed to reduce the thickness of the glass and improve mechanical stability. Meet the requirements for writing tests.
Higher flexibility characteristics and mechanical stability are achieved, extending the service life of OLED displays, and reducing manufacturing costs, avoiding waste and potential damage in the laser stripping process.
Smart Images
Figure CN115989203B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a substrate made of glass, which has at least one substantially dimensionally stable section and at least one flexible section, and to a method for producing the substrate. Background Art
[0002] In particular in the case of small devices, for example portable devices, such substrates made of glass are becoming increasingly important as displays, for example based on organic light-emitting diodes (OLED) for display purposes.
[0003] It is known to design OLED displays in a flexible manner. For this purpose, methods are already known for the subsequent structuring of flexible organic light-emitting diodes (FOLEDs), in which one or more layers are removed again stepwise from the stacked layer arrangement by means of laser radiation (ablation).
[0004] Since OLED displays can be made of organic material layers on a flexible carrier substrate, including flexible driving circuits, OLED displays can be adapted to non-planar surfaces or used in structures that have inherently flexible properties.
[0005] The sensitivity of OLED materials to oxygen and / or moisture has proven to be problematic, resulting in a relatively short service life. This can be solved, for example, by placing the actual OLED components between two glass layers that are essentially free of oxygen and / or vapor diffusion.
[0006] Another possibility is to use OLED displays on glass substrates with barrier layers. These barrier layers can consist, for example, of silicon oxide (SiO2), (boro) silicates, aluminates (Al2O3) or metal layers (Al, Ag, Au, Rh) or other corresponding materials.
[0007] If the thickness of the glass layer is below a certain limit, such OLED structures or devices remain flexible. Typically, OLEDs with a glass layer and a thickness of 100 μm or less still have the necessary flexibility for most purposes.
[0008] However, such thin glass layers, ie below 50 μm or even below 20 μm, are fragile and prone to breakage due to their brittleness. Therefore, from this aspect, it is desirable to connect such OLEDs to a mechanically fixed (flexible or non-flexible) carrier substrate for stabilization purposes.
[0009] When producing the classic display screens of smartphones, a carrier substrate made of glass is used as the bottom layer, the so-called “back plane.” The properties of technical glass are ideal for the requirements of back planes.
[0010] The development of foldable displays for new smartphones is accompanied by a significant change in the process sequence. In current processing methods, the backplane made of glass, which is initially used to stabilize and fix the electronic components, must be removed after the components have been applied in a complex and waste-increasing process (Laser Lift-Off process). In this way, only the flexible parts of the display are left without the protective backplane.
[0011] The laser lift-off process involves transferring the microelectronic functional layers to a new, lighter and thinner carrier substrate. Here, the layers are usually separated by selective laser ablation and evaporation of strongly absorbing intermediate layers (usually polymer layers). It is crucial that the adjacent microelectronic functional layers are not affected by the energy of the laser radiation.
[0012] Whether it is for smartphones, tablets or e-readers, their production always has something in common: the circuit layer for individual pixel control is no longer located on a rigid glass carrier, but on a flexible layer.
[0013] Disadvantages of conventional laser lift-off processes are the high process time / manufacturing costs and the waste additionally generated by the process since the display may be damaged during the process.
[0014] Such flexible display devices are known, for example, from EP 3 206 108 B1, EP 3 456 036 A1 or EP 2 709 091 B1.
[0015] In addition, US 2016 / 0 057 834A1 relates to a method for manufacturing a substrate for a display module. A substrate body having a signal circuit area is applied to a transparent carrier plate. A plurality of openings are introduced on the substrate body, and the lower surface is etched by high-energy light penetrating the transparent carrier plate so as to separate the substrate body from the transparent carrier plate.
[0016] JP 2013-009016 A relates to a plurality of thin-film elements on a semiconductor layer, wherein etching grooves are introduced between the plurality of thin-film elements by laser etching. Summary of the invention
[0017] The object of the present invention is to create a carrier substrate for displays which has significantly improved flexibility properties and at the same time meets the high requirements on the stress of the glass surface, for example in the form of a so-called pen drop test.
[0018] According to the invention, the foldable substrate made of glass has the following properties, in particular for display applications:
[0019] 1. Introducing a discontinuous structure on one side in order to reduce the glass thickness, which results in foldability and high mechanical stability (proven by means of a pen drop test).
[0020] 2. At least two regions with different thicknesses.
[0021] 3. Thickness in the joint region <100 μm, preferably <50 μm, preferably <30 μm.
[0022] 4. Filled with polymer.
[0023] 5. The bottom is formed by a spherical concave portion.
[0024] 6. The recesses can be arranged in different ways, such as close sphere packing (or hexagonal arrangement) or square arrangement.
[0025] 7. Meet the pen drop test (simply compared only to thin areas)
[0026] 8. Multiple areas can have different glass thickness and original thickness. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention allows different embodiments. In order to further illustrate its basic principle, one of the embodiments is shown in the accompanying drawings and described below. In the accompanying drawings:
[0028] Figure 1 shows a cross-sectional view of a substrate made of glass;
[0029] Figure 2 shows an enlarged cross-sectional view of a substrate;
[0030] Figure 3 shows an enlarged cross-sectional view of a substrate;
[0031] FIG4 shows a schematic distribution of recesses in a substrate in a top view;
[0032] Figure 5 The sequence of edge rounding of the modified portion is shown in different stages during etching. DETAILED DESCRIPTION
[0033] The invention relates to a device made of glass having at least two regions:
[0034] At least one region is not collapsible.
[0035] At least one region is collapsible.
[0036] The foldable area has a microstructure on one side.
[0037] The microstructure has a concave area below the centerline with a smooth course.
[0038] The microstructure has a raised area above the centerline that has a non-smooth course.
[0039] The method for producing a substrate 1 made of glass is based on the creation of a linear modification 2 having a linear modification as in Figure 5 4 and the defined distances in the x and y directions. Each modification 2 ends with a modification depth t in the volume of the substrate 1. Once the modified glass of the substrate 1 has been removed by wet etching, the etching process proceeds isotropically in the remaining substrate 1. A recess 3 is formed which is at a distance from the opposite surface of the substrate 1 and has a residual thickness d, the reaching of which also defines the overall etching duration.
[0040] like Figure 1 As shown, the substrate 1 shown here by way of example consists of a substantially dimensionally stable section 4 and at least one flexible, in particular bendable, elastic and / or foldable section 5, wherein, at least in the flexible section 5, a recess 6 which is one-sided or does not pass through the substrate 1 is introduced into the outer surface of the substrate 1 by means of a plurality of recesses 3 as microstructures 12, thereby reducing the material thickness D of the substrate 1 in the flexible section 5 compared to the adjacent section 4 to a residual thickness d. The recess 6 is filled with a polymer 7, which can have optical properties similar to the glass material of the substrate 1, for example.
[0041] Here, the groove 6 is formed by a plurality or a large number of recesses 3 in the remaining substrate material and is delimited by a plurality of regularly arranged concave microstructures 12, the shaping of which also determines the remaining material thickness as the remaining thickness d of the substrate 1 in the flexible section 5. The recesses 3 extend with their minimum depth to a maximum depth in a region of the substrate 1 parallel to the outer surface with a thickness S, which region encompasses the plane of the neutral axis 8 between the elongation region 9 and the compression region 10 of the substrate 1 when the substrate 1 is bent due to an external force F.
[0042] The following aspects constitute the basic implementation of the present invention:
[0043] A foldable or flexible section 5 with recesses 3 which are delimited by periodically arranged microstructures 12 .
[0044] The periodically arranged microstructures 12 each have a center in which the glass thickness or residual thickness d is minimum.
[0045] The periodically arranged microstructures 12 may be arranged in a rectangular shape.
[0046] The distance Ax of the centers of the rectangularly arranged microstructures 12 in the folding direction 11 is at least 20% greater than the distance Ay of the centers of the microstructures 12 transversely to the folding direction 11 .
[0047] The recess 3 is filled with a polymer 7 .
[0048] The polymer 7 has approximately the same refractive index as the glass material of the substrate 1 in the visible spectrum.
[0049] • Polymer 7 is flexible.
[0050] • The substrate 1 containing the polymer filler passes the pen drop test in the foldable area.
[0051] A transition region can be produced between the dimensionally stable section 4 and the flexible section 5 which has a continuously decreasing glass thickness with a continuously decreasing residual thickness d.
[0052] Among them, the following provisions shall apply:
[0053] "Foldable": curvature radius <20cm
[0054] "Above": On the side away from the glass
[0055] "Bottom": On the side facing the glass
[0056] “Concave”: bends toward the glass
[0057] "Convex": Curved in the opposite direction of the concave arch
[0058] “Center line”: an imaginary line that is equidistant from the uppermost and lowermost points of a microstructure in the glass
[0059] “Pen drop test”: A ballpoint pen (BIC Easy Slip, weight 5.73 g) is dropped from a height of 20 cm with the tip (made of tungsten carbide with a diameter of 0.7 mm) onto the workpiece and the fracture of the workpiece is determined.
[0060] "Glass": Materials containing glass components, including glass ceramics
[0061] "x direction": along the surface of the glass body, perpendicular to the folding direction
[0062] "y direction": along the surface of the glass body, parallel to the folding direction
[0063] "z direction": perpendicular to x and y
[0064] The microstructure 12 which delimits the concave recess 3 at its bottom ensures mechanical stability in regions of less glass thickness; similar to the roof of a Gothic church, the microstructure 12 has only a rounded concave structure on the boundary surface on the side facing the remaining glass material of the substrate 1. Peaks are avoided, whereby the mechanical stability of the thin region or regions is higher than that of a completely smooth bottom surface.
[0065] This has been demonstrated with the aid of a pen drop test: This test is particularly important and useful for glass used for displays. The pen first falls on the glass with the tip. If the glass breaks, it is not stable enough for display applications. This happens on flat, thin glass. If a structure that meets the above characteristics is introduced according to the invention, the glass passes the pen drop test even if the thickness of the glass is not increased.
[0066] like Figure 3 As can be seen in FIG, the thicknesses of the polymer 7 and the substrate 1 are chosen such that the neutral axis 8 is located in the region of the concave microstructures 12, as close as possible to the spherical bottom. Ideally, the neutral axis 8 coincides with the bottom plane.
[0067] exist Figure 2 and 3 The corresponding design of the recesses 3 in the flexible section 5 is shown in FIG. The spherical shape of the microstructures 12 creates a protruding, tapering intermediate region 13 between the recesses 3, which points only in the direction of the polymer 7 as the filling material. In the direction of the remaining glass material of the substrate 1, the boundary surface of the microstructure 12 has a completely smooth rounded structure. The boundary surface formed by a plurality of spherical or ellipsoidal surface sections adjoining one another leads to a high load-bearing capacity despite the reduced residual thickness d, and also leads to flexibility in the filling direction of the polymer 7.
[0068] Here, if Figure 3 As shown, the ratio of the recess 3 filled with the polymer 7 to the residual thickness d of the glass substrate is selected by means of the modified depth t so that the neutral axis 8 is located in the region of the concave microstructure 12, preferably at the spherical bottom of the center of the microstructure 12 with the minimum residual thickness dmin. Ideally, the neutral axis 8 coincides with the plane determined by the minimum residual thickness dmin.
[0069] FIG4 shows a possible arrangement or distribution of the recesses 3 in the substrate 1. Figure 4a The deepest point of the spherical recess 3 in the hexagonal arrangement or close sphere packing shown in FIG. 1 is located at the center of the recess 3 and at Figure 4a The hexagonal arrangement or close sphere packing shown in FIG. 1 minimizes the tips or tapering middle regions 13 between the recesses 3 facing the polymer filler, because the stresses are largely evenly distributed over the surface, so that the hexagonal arrangement or close sphere packing obtains advantages when twisting in different directions.
[0070] exist Figure 4b A square arrangement is shown in FIG. 1 , which has a consistent distance from all adjacent recesses 3 and a correspondingly uniform flexibility characteristic, while Figure 4c An advantageous arrangement of folds in the horizontal direction is shown by way of example, which has different distances Ax and Ay in the x-direction and in the y-direction corresponding to the folding direction 11 .
[0071] Once in Figure 5 As shown in FIG. 2 , when the modification depth t is reached, the etching progress in the substrate 1 proceeds substantially isotropically, which increasingly leads to edge rounding of the produced recesses 3 in the tip region at the end of the modification 2. Therefore, in particular during etching, the substrate 1 becomes thinner and the diameters D1 to D3 of the recesses 3 become larger. The edge rounding is thus achieved by “overetching”.
[0072] Reference numerals list
[0073] 1 substrate
[0074] 2 Modification Department
[0075] 3 concave parts
[0076] 4 sections
[0077] 5 sections
[0078] 6 grooves
[0079] 7 Polymer
[0080] 8 Neutral axis
[0081] 9 Elongation Zone
[0082] 10 Compression Area
[0083] 11 Folding direction
[0084] 12 Microstructure
[0085] 13. Middle Area
[0086] tModification depth
[0087] dRemaining thickness
[0088] DMaterial thickness
[0089] SThickness
[0090] F force
[0091] Ax distance
[0092] Ay distance
[0093] D1 Diameter
[0094] D2 diameter
[0095] D3 diameter
Claims
1. A substrate (1) made of glass, comprising at least one dimensionally stable section (4) and at least one flexible section (5), wherein: At least in the flexible section (5), a groove (6) is introduced into the outer surface of the substrate (1) on one side and not passing through the substrate (1), whereby the material thickness of the substrate (1) in the flexible section (5) is reduced compared to the adjacent dimensionally stable section (4), wherein at least one groove (6) is formed by a plurality of concave recesses (3), which are delimited by microstructures (12), the course of which determines the remaining material thickness of the substrate (1) in the flexible section (5), wherein the recesses (3) extend at least in sections into a region having a thickness S parallel to the outer surface, which region surrounds the plane of the neutral axis (8) between the extension region (9) and the compression region (10) of the substrate (1) when the substrate (1) is bent.
2. The substrate (1) according to claim 1, characterized in that The flexible section (5) is a bendable, elastic and / or foldable section.
3. The substrate (1) according to claim 1, characterized in that The at least one groove (6) is formed by a plurality of regularly arranged concave recesses (3).
4. The substrate (1) according to claim 1, characterized in that The plane of the neutral axis (8) extends between the bottom of the concave recess (3) and the edge region between adjacent recesses (3).
5. The substrate (1) according to claim 1, characterized in that At least a single groove (6) has a polymer filling material.
6. The substrate (1) according to claim 5, characterized in that The polymer filling material has a filling height corresponding to the adjacent dimensionally stable section (4).
7. The substrate (1) according to claim 5, characterized in that The polymer filler material has a refractive index at least consistent with the refractive index of glass in the visible spectrum.
8. The substrate (1) according to claim 5, characterized in that The polymer filling material has flexible and / or elastic material properties.
9. The substrate (1) according to claim 1, characterized in that The recesses (3) are formed by microstructures (12) which are arranged periodically at least in sections or in a regular pattern.
10. The substrate (1) according to claim 1, characterized in that The recesses (3) are arranged in a geometric pattern.
11. The substrate (1) according to claim 10, characterized in that The recesses (3) are arranged in a rectangular pattern.
12. The substrate (1) according to claim 1, characterized in that The distance between adjacent recesses (3) in the bending or folding direction is greater than the distance in the transverse direction of the bending or folding.
13. The substrate (1) according to claim 12, characterized in that The distance between adjacent recesses (3) in the direction of bending or folding is at least 20% greater than the distance in the transverse direction of the bending or folding.
14. The substrate (1) according to claim 1, characterized in that The recesses (3) each have a center in which the remaining material thickness of the base plate (1) in the flexible section (5) is minimal.
15. The substrate (1) according to claim 1, characterized in that The recess (3) is designed to be rotationally symmetrical.
16. The substrate (1) according to claim 15, characterized in that The recess (3) is spherical in design.
17. The substrate (1) according to claim 1, characterized in that In at least one flexible section (5), the remaining material thickness of the base plate (1) is designed by means of different recesses (3).
18. The substrate (1) according to claim 17, characterized in that In at least one flexible section (5), the remaining material thickness of the base plate (1) is designed to be continuously reduced or increased by means of different recesses (3).
19. The substrate (1) according to claim 17, characterized in that In a plurality of adjacent flexible sections (5), the remaining material thickness of the base plate (1) is designed by means of different recesses (3).
20. The substrate (1) according to claim 1, characterized in that The remaining material thickness in the flexible section (5) is less than 100 μm.
21. The substrate (1) according to claim 1, characterized in that The recesses (3) are arranged in the flexible section (5) according to the principle of close spherical packing, hexagonal arrangement or square arrangement.
22. The substrate (1) according to claim 1, characterized in that The recess (3) is introduced on the principle of a Gothic cathedral roof.
23. A method for producing a substrate (1) made of glass according to any one of claims 1 to 22, the substrate having at least one dimensionally stable section (4) and at least one flexible section (5), wherein: At least in the flexible section (5), a groove (6) which is unilateral and does not pass through the substrate (1) is introduced as a microstructure (12) into the outer surface of the substrate (1), thereby reducing the material thickness of the substrate (1) in the flexible section compared to an adjacent section by material removal using an etching process, in which a modified portion (2) with a defined modified depth t is introduced into the flexible section (5) by means of laser radiation into a region parallel to the outer surface, and the modified portion (2) is subsequently subjected to an etching action, thereby removing material until the recess (3) produced in this way extends to the region at least over a majority of the material thickness of the substrate (1), wherein the recess (3) is produced as a concave recess (3) in which anisotropic material removal is first produced in the region of the modified portion (2), and then the etching process is continued until isotropic material removal occurs, thereby producing an at least largely continuous course of the recess (3).
24. The method according to claim 23, characterized in that The isotropic material removal is continued until the recess (3) is rounded in this region.
25. The method according to claim 24, characterized in that The rounding is spherical.