Back film, display module and display device

Abstract

A back film, which is applied to a display module. The back film comprises a first adhesive layer, a substrate layer, a second adhesive layer and a protective layer that are stacked, wherein the elastic modulus of the material of the second adhesive layer is less than the elastic modulus of the material of the substrate layer, and the elastic modulus of the material of the first adhesive layer is less than or equal to the elastic modulus of the material of the second adhesive layer.

Description

A back film, a display module, and a display device

[0001] This application claims priority to Chinese patent application No. 202510053413.4, filed on January 13, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of display technology, and more particularly to a back film, a display module, and a display device. Background Technology

[0003] Currently, most display module circuit designs use COF (Chip On Flex, or Chip On Film) design, which means that COF technology is used to bond the driver chip, i.e., integrated circuit (IC), to the display panel during the manufacturing process of the display module.

[0004] COF (Chip-on-Flight) technology is an integrated circuit packaging technology that uses a flexible circuit board to fix integrated circuits onto a flexible circuit board. This technology uses a flexible additional circuit board as a carrier for packaging chips, combining the chip with the flexible substrate circuit, or it refers to a flexible additional circuit board without packaged chips. Summary of the Invention

[0005] On one hand, a back film is provided for use in a display module. The back film includes a first adhesive layer, a substrate layer, a second adhesive layer, and a protective layer stacked together. The elastic modulus of the material of the second adhesive layer is less than that of the material of the substrate layer, and the elastic modulus of the material of the first adhesive layer is less than or equal to that of the material of the second adhesive layer.

[0006] In some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the first adhesive layer is in the range of 0.05 MPa to 0.5 MPa.

[0007] In some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the second adhesive layer is in the range of 0.2 MPa to 1 MPa.

[0008] In some embodiments, the thickness of the first adhesive layer ranges from 10 μm to 30 μm.

[0009] In some embodiments, the thickness of the second adhesive layer ranges from 10 μm to 30 μm.

[0010] In some embodiments, the thickness of the first adhesive layer is equal to the thickness of the second adhesive layer.

[0011] In some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the substrate layer material ranges from 2 GPa to 3 GPa.

[0012] In some embodiments, the thickness of the substrate layer ranges from 25 μm to 75 μm.

[0013] In some embodiments, the elastic modulus of the protective layer material is greater than or equal to the elastic modulus of the substrate layer material.

[0014] In some embodiments, under conditions where the temperature range is 10°C to 40°C, the elastic modulus of the protective layer material is in the range of 3 GPa to 4 GPa.

[0015] In some embodiments, the thickness of the protective layer ranges from 25 μm to 150 μm.

[0016] On the other hand, a display module is provided, including a display panel and a back film as described above, wherein the back film is disposed on the non-display side of the display panel, and a first adhesive layer of the back film is attached to the display panel.

[0017] In another aspect, a display module is provided, including a display panel and a first adhesive layer and a substrate layer of a back film as described above; the first adhesive layer and the substrate layer are located on the non-display side of the display panel, and the first adhesive layer is attached to the display panel.

[0018] In some embodiments, the display module further includes a support plate located on the side of the substrate layer away from the display panel.

[0019] In another aspect, a display device is provided, including a display module and a driver chip as described above, wherein the driver chip is used to drive the display module to display. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0021] Figure 1 is a cross-sectional view of a display device according to some embodiments;

[0022] Figure 2 is a structural diagram of the corresponding driver chip bonding steps according to some embodiments;

[0023] Figure 3 is a cross-sectional view of a backsheet according to some embodiments;

[0024] Figure 4 is another cross-sectional view of a display device according to some embodiments. Detailed Implementation

[0025] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0026] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0027] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0028] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0029] For example, as shown in FIG1, the display device 1000 may include a display module 100 and a driver chip 200.

[0030] In some embodiments, as shown in FIG1, the display module 100 can be stacked, and the display module 100 may include a support plate 10, a back film 20, a display panel 30, a polarizer 40, a transparent optical adhesive layer 50 and a cover plate 60 stacked sequentially from bottom to top.

[0031] For example, the display panel 30 can be used to display images; the display panel 30 can be, for example, an organic light-emitting diode (OLED) display panel, a micro organic light-emitting diode (Micro OLED) display panel, a quantum dot light-emitting diode (QLED) display panel, a mini light-emitting diode (Mini LED) display panel, or a micro light-emitting diode (Micro LED) display panel, etc., and this disclosure is not limited thereto.

[0032] For example, the display panel 30 can be a flexible display panel or a rigid display panel, and this disclosure does not limit it.

[0033] For example, as shown in FIG1, the driver chip 200 is connected to the display panel 30 in the display module 100. The driver chip 200 is configured to provide electrical signals, such as control signals, to the display panel 30 in the display module 100. The driver chip 200 may be, for example, a central processing unit, a digital signal processor, a microcontroller, or a programmable logic controller.

[0034] For example, as shown in FIG1, the polarizer 40, the transparent optical adhesive layer 50, and the cover plate 60 of the display module 100 are disposed on the display surface A side of the display panel 30, that is, on the light-emitting side of the display panel 30. The polarizer 40 can be used to enhance the contrast and clarity of the image displayed on the display panel 30. By blocking unnecessary polarized light, it reduces the interference of scattered light and stray light, allowing the observer to see a clearer and more vivid image. The cover plate 60 can be, for example, a glass cover plate. The transparent optical adhesive layer 50 is used to bond the cover plate 60 to the polarizer 40.

[0035] For example, as shown in FIG1, the support plate 10 and the back film 20 of the display module 100 are disposed on the non-display surface B side of the display panel 30, that is, on the back side of the display panel 30.

[0036] In some embodiments, as shown in FIG1, the side of the display panel 30 where the driving chip 200 is located can be bent to the non-display surface B side of the display panel 30 to reduce the width of the bezel of the display device 1000, thereby achieving a narrow bezel configuration. It is understood that the support plate 10 and the back film 20 located on the non-display surface B side of the display panel 30 are also bent along with the display panel 30.

[0037] For example, the support plate 10 mainly serves a supporting function, providing certain support for the display panel 30, preventing the display panel 30 from deforming, and enhancing the support capability of the display module 100; the material of the support plate 10 can be, for example, a metal material.

[0038] In some embodiments, the material of the back film 20 may be, for example, PET (Polyethylene terephthalate), and in other embodiments, the material of the back film 20 may be, for example, PI (Polyimide). Both PET and PI are flexible materials.

[0039] For example, PET material is relatively inexpensive and easy to process, so most display devices 1000 use PET material for the back film 20. However, PET material has a large elastic modulus, for example, the elastic modulus of PET material can range from 3GPa to 4GPa. PET material has poor mechanical properties and poor deformation resilience. When the display panel 30 is a folding display panel or a curved display panel, the PET material back film 20 is provided on the non-display surface B side of the display panel 30. The poor mechanical properties and poor deformation resilience of the back film 20 will affect the durability of the folding display panel or the curved display panel, and may easily cause problems such as the folding display panel or the curved display panel falling off.

[0040] For example, the elastic modulus of PI material is smaller than that of PET material. For instance, the elastic modulus of PI material can range from 2 GPa to 3 GPa. PI material has excellent mechanical properties and high tensile strength. Therefore, a back film 20 of PI material can be applied to the non-display surface B side of a foldable display panel or curved display panel. The back film 20 of PI material can improve the durability of the foldable display panel or curved display panel and prevent problems such as the foldable display panel or curved display panel detaching.

[0041] The elastic modulus is a physical quantity that describes the elasticity of a material. It represents the stress divided by the strain in that direction under uniaxial stress. During elastic deformation, the stress and strain of a material are directly proportional (i.e., they obey Hooke's Law), and this proportionality constant is called the elastic modulus. The larger the elastic modulus, the stiffer the material; the smaller the elastic modulus, the softer the material.

[0042] For example, as shown in FIG2 and referring to FIG1, when the back film 20 of the above-mentioned PI material or the back film 20 of PET material is provided on the non-display surface B side of the display panel 30, and the driving chip 200 is bonded to the display panel 30 using COF technology, the driving chip 200 can be disposed on the flip film 1, and the flip film 1 can be bonded to the display panel 30. During the bonding process between the flip-chip film 1 and the display panel 30, the pressure applied to the display panel 30 by the pressure head is relatively large, and the elastic modulus of PI and PET materials is relatively large and they are relatively rigid. This pressure cannot be released through the back film 20 of the PI material or the back film 20 of the PET material. Therefore, cracks will be pressed into the area near the bonding area on the display panel 30 during the bonding process. In addition, the display device 1000 also needs to be equipped with a circuit board, such as a PCB (Printed Circuit Board). During the manufacturing or transportation of the display device 1000, the circuit board is thick and heavy, and it is inevitable that the circuit board will sag and pull on the display panel 30. The display panel 30 is prone to crack extension after being pulled, and the crack will continue to extend to the signal lines of the display area of ​​the display panel 30, resulting in problems such as bright lines and abnormal display functions.

[0043] In some embodiments, as shown in FIG3 and referring to FIG1, a back film 20 is provided for use in a display module 100. The back film 20 includes a first adhesive layer 21, a substrate layer 22, a second adhesive layer 23, and a protective layer 24 stacked together. The elastic modulus of the material of the second adhesive layer 23 is less than that of the material of the substrate layer 22, and the elastic modulus of the material of the first adhesive layer 21 is less than or equal to that of the material of the second adhesive layer 23.

[0044] In some embodiments, as shown in FIG3 and referring to FIG1, the back film 20 includes a protective layer 24, a second adhesive layer 23, a substrate layer 22, and a first adhesive layer 21 stacked sequentially from bottom to top; the second adhesive layer 23 can be used to bond the protective layer 24 to the substrate layer 22, and the first adhesive layer 21 can be used to bond the substrate layer 22 to the display panel 30, thereby achieving the bonding of the back film 20 and the display panel 30.

[0045] For example, the protective layer 24 can be used to protect the substrate layer 22 and provide support for the substrate layer 22 to prevent damage to the substrate layer 22 and improve the yield of the display module 100.

[0046] In some embodiments, the materials of the first adhesive layer 21 and the second adhesive layer 23 may both be viscous organic materials, and the elastic modulus of the materials of the first adhesive layer 21 and the second adhesive layer 23 may both be less than the elastic modulus of the material of the substrate layer 22 (e.g., it may be PET or PI).

[0047] For example, the elastic modulus of the material of the first adhesive layer 21 is less than that of the material of the substrate layer 22. The first adhesive layer 21 is softer and more elastic than the substrate layer 22, and has a better ability to buffer stress. Moreover, the first adhesive layer 21 is closer to the display panel 30 than the substrate layer 22. When the driver chip 200 is bonded to the display panel 30 using COF technology, the greater pressure applied to the display panel 30 can be transmitted to the first adhesive layer 21. The first adhesive layer 21 has a better ability to buffer stress, and this part of the pressure can be released through the first adhesive layer 21. This can effectively prevent cracks from being pressed into the area near the bonding area on the display panel 30, thereby effectively avoiding problems such as bright lines and abnormal display functions after the display panel 30 is stretched. This makes the display module 100 more reliable and durable in reliability verification.

[0048] For example, the elastic modulus of the material of the second adhesive layer 23 is less than that of the material of the substrate layer 22. The second adhesive layer 23 is softer, more elastic, and has a better stress-buffering ability than the substrate layer 22. A small portion of the pressure that is not released by the first adhesive layer 21 can be transmitted to the second adhesive layer 23 through the substrate layer 22. The second adhesive layer 23 has a better stress-buffering ability, and this small portion of the pressure can be released through the second adhesive layer 23, further effectively preventing cracks from being pressed into the area where the display panel 30 is bonded. This effectively avoids problems such as bright lines and abnormal display functions after the display panel 30 is stretched, making the display module 100 more reliable and durable in reliability verification.

[0049] In some embodiments, the elastic modulus of the material of the first adhesive layer 21 may be less than or equal to the elastic modulus of the material of the second adhesive layer 23.

[0050] For example, when the elastic modulus of the material of the first adhesive layer 21 is equal to the elastic modulus of the material of the second adhesive layer 23, the stress release capability of the first adhesive layer 21 is the same as that of the second adhesive layer 23. The first adhesive layer 21 and the second adhesive layer 23 cooperate to effectively prevent cracks from being pressed into the vicinity of the area where the display panel 30 is bonded. In addition, the second adhesive layer 23 can also be used to protect the substrate layer 22 and prevent damage to the substrate layer 22.

[0051] For example, when the elastic modulus of the material of the first adhesive layer 21 is less than that of the material of the second adhesive layer 23, the first adhesive layer 21 is softer than the second adhesive layer 23. The first adhesive layer 21 has a better stress-relieving ability than the second adhesive layer 23. Most of the pressure applied to the display panel 30 can be released by the first adhesive layer 21 in the first time. A small portion of the pressure that is not released can be transmitted to the second adhesive layer 23, which releases it. The first adhesive layer 21 and the second adhesive layer 23 work together to further effectively prevent cracks from being pressed into the area where the display panel 30 is bonded. Furthermore, since the second adhesive layer 23 is more rigid than the first adhesive layer 21, the second adhesive layer 23 can both protect the substrate layer 22 and provide some support for the substrate layer 22 to prevent damage to the substrate layer 22.

[0052] In some embodiments, the elastic modulus of the material of the first adhesive layer 21 is relatively small. For example, the maximum elastic modulus of the material of the first adhesive layer 21 may be 0.03 MPa. The material of the first adhesive layer 21 is relatively soft, easily deformed, and has weak resilience. When bonding the driver chip 200 to the display panel 30 using COF technology, the first adhesive layer 21 is prone to deformation under high pressure. This results in a thinner area on the first adhesive layer 21 subjected to pressure, and a weaker resilience, making it unable to withstand high pressure and reducing its stress release ability. Consequently, the pressure applied to the display panel 30 cannot be released in time, causing cracks to form near the bonding area on the display panel 30. Furthermore, due to the high temperature during the bonding process using COF technology, the relatively soft material of the first adhesive layer 21 becomes even softer, leading to significant adhesive overflow. This causes the material of the first adhesive layer 21 to adhere to some film layers of the display panel 30. When the temperature returns to room temperature, for example, between 10°C and 40°C, the material of the first adhesive layer 21 can cause cracks in some film layers (such as inorganic insulating film layers) of the display panel 30 that are bonded to it, thereby reducing the yield of the display module 100.

[0053] Therefore, in some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the material of the first adhesive layer 21 is in the range of 0.05 MPa to 0.5 MPa.

[0054] For example, at room temperature, the elastic modulus of the material of the first adhesive layer 21 is in the range of 0.05 MPa to 0.5 MPa. The approximate range of room temperature is, for example, 10°C to 40°C. For example, the room temperature can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C, etc. This disclosure does not impose any limitations.

[0055] For example, at room temperature, the elastic modulus of the material of the first adhesive layer 21 can be, for example, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa, etc., and this disclosure does not impose any limitations.

[0056] For example, at room temperature, the elastic modulus of the material of the first adhesive layer 21 is in the range of 0.05 MPa to 0.5 MPa. The elastic modulus of the material of the first adhesive layer 21 is greater than the maximum elastic modulus of 0.03 MPa of the material of the first adhesive layer 21 in the above embodiment. This makes the flexibility and rigidity of the first adhesive layer 21 more suitable for the back film 20. It can effectively avoid the phenomenon of glue overflow due to high temperature when using COF technology to bond the driver chip 200 to the display panel 30. Moreover, it is not easy to deform under pressure, has good resilience, and has a high stress release ability. When using COF technology to bond the driver chip 200 to the display panel 30, the large pressure applied to the display panel 30 can be transmitted to the first adhesive layer 21. This part of the pressure can be released through the first adhesive layer 21, which can effectively prevent cracks from being pressed into the area near the bonding on the display panel 30. This avoids problems such as bright lines and abnormal display functions after the display panel 30 is stretched, making the display module 100 more reliable and durable in reliability verification.

[0057] In some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the material of the second adhesive layer 23 is in the range of 0.2 MPa to 1 MPa.

[0058] For example, when the temperature is 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C, the elastic modulus of the material of the second adhesive layer 23 can be, for example, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, 0.55MPa, 0.6MPa, 0.65MPa, 0.7MPa, 0.75MPa, 0.8MPa, 0.85MPa, 0.9MPa, 0.95MPa or 1MPa, etc., and this disclosure does not impose any limitations.

[0059] At room temperature, the elastic modulus of the material of the second adhesive layer 23 is in the range of 0.2 MPa to 1 MPa. The elastic modulus of the material of the first adhesive layer 21 is greater than the maximum elastic modulus of the material of the first adhesive layer 21 in the above embodiment, which is 0.03 MPa. This makes the flexibility and rigidity of the second adhesive layer 23 more suitable for the back film 20. It can effectively avoid the phenomenon of glue overflow caused by high temperature when using COF technology to bond the driver chip 200 to the display panel 30. Moreover, it is not easy to deform under pressure and has good resilience. When using COF technology to bond the driver chip 200 to the display panel 30, the stress that is not released by the first adhesive layer 21 can be released through the second adhesive layer 23. This can effectively prevent cracks from being pressed into the area near the bonding on the display panel 30, thereby avoiding problems such as bright lines and abnormal display functions after the display panel 30 is stretched. This makes the display module 100 more reliable and durable in reliability verification.

[0060] For example, the elastic modulus of the material of the second adhesive layer 23 can be larger than that of the material of the first adhesive layer 21, that is, the second adhesive layer 23 can be more rigid than the first adhesive layer 21. While releasing the stress that the first adhesive layer 21 has not released, the second adhesive layer 23 can also provide protection for the substrate layer 22 and provide a certain support for the substrate layer 22, so as to avoid damage to the back film 20 due to insufficient support of the substrate layer 22.

[0061] For example, the elastic modulus of the material of the second adhesive layer 23 can be approximately equal to that of the material of the first adhesive layer 21, so that the flexibility of the second adhesive layer 23 and the first adhesive layer 21 is approximately the same. The second adhesive layer 23 can release the stress that the first adhesive layer 21 has not released over a larger area, which can effectively prevent cracks from being pressed into the area where the display panel 30 is bonded. This avoids problems such as bright lines appearing on the display panel 30 after it is stretched, making the display module 100 more reliable and durable in reliability verification.

[0062] In some embodiments, the thickness of the first adhesive layer 21 ranges from 10 μm to 30 μm.

[0063] For example, the thickness of the first adhesive layer 21 can be, for example, 10μm, 15μm, 20μm, 25μm or 30μm, etc., and this disclosure does not limit it.

[0064] For example, the thickness of the first adhesive layer 21 is in the range of 10μm to 30μm, which ensures that the first adhesive layer 21 has suitable adhesion, so that the display panel 30 and the substrate layer 22 are firmly bonded, and problems such as the display panel 30 or the substrate layer 22 falling off or misaligning are not likely to occur. In addition, the first adhesive layer 21 is not easily deformed when subjected to a certain pressure. The first adhesive layer 21 has sufficient stress release capability, so that when the driver chip 200 is bonded to the display panel 30 using COF technology, the pressure applied to the display panel 30 can be released in time. This effectively prevents cracks from being pressed into the area where the display panel 30 is bonded. At the same time, the thickness of the first adhesive layer 21 is in the range of 10μm to 30μm, which can effectively prevent adhesive overflow. For example, when the first adhesive layer 21 is too thick, more material is required for the first adhesive layer 21. When the temperature is high when using COF technology to bond the driver chip 200 to the display panel 30, the material of the first adhesive layer 21 becomes soft under the influence of the high temperature, and some of the material will overflow, resulting in adhesive overflow.

[0065] In some embodiments, the thickness of the second adhesive layer 23 ranges from 10 μm to 30 μm.

[0066] For example, the thickness of the second adhesive layer 23 can be, for example, 10μm, 15μm, 20μm, 25μm or 30μm, etc., and this disclosure does not limit it.

[0067] For example, the thickness of the second adhesive layer 23 is in the range of 10μm to 30μm, which ensures that the second adhesive layer 23 has suitable adhesion, so that the protective layer 24 and the substrate layer 22 are firmly bonded, and problems such as the protective layer 24 or the substrate layer 22 falling off or misaligning are not likely to occur. In addition, the second adhesive layer 23 is not easily deformed when subjected to a certain pressure. The second adhesive layer 23 has a certain stress release capability. When the driver chip 200 is bonded to the display panel 30 using COF technology, the stress that has not been released by the first adhesive layer 21 can be released through the second adhesive layer. Release 23 effectively prevents cracks from being pressed into the area where the display panel 30 is bonded; at the same time, the thickness of the second adhesive layer 23, which is in the range of 10μm to 30μm, can effectively prevent adhesive overflow. For example, when the second adhesive layer 23 is too thick, more material is required for the second adhesive layer 23. When the temperature is high when using COF technology to bond the driver chip 200 to the display panel 30, the material of the second adhesive layer 23 becomes soft under the influence of the high temperature, and some of the material will overflow, resulting in adhesive overflow.

[0068] In some embodiments, the thickness of the first adhesive layer 21 may be equal to the thickness of the second adhesive layer 23. This arrangement makes the thickness of some film layers of the back film 20 uniform, increases the thickness uniformity of the back film 20, simplifies the manufacturing process, and saves costs.

[0069] In some embodiments, under a temperature range of 10°C to 40°C, the elastic modulus of the substrate layer 22 is in the range of 2 GPa to 3 GPa.

[0070] For example, when the temperature is 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C, the elastic modulus of the material of the substrate layer 22 can be, for example, 2 GPa, 2.1 GPa, 2.2 GPa, 2.3 GPa, 2.4 GPa, 2.5 GPa, 2.6 GPa, 2.7 GPa, 2.8 GPa, 2.9 GPa or 3 GPa, etc., and this disclosure does not limit it.

[0071] For example, the material of the substrate layer 22 can be PI material, or it can be other materials or combinations of materials with an elastic modulus of 2 GPa to 3 GPa. This disclosure does not limit the material. The substrate layer 22 is used to protect the display panel 30, provide support for the display panel 30, and block moisture in the air to prevent moisture from entering the display panel 30.

[0072] For example, when the substrate layer 22 is made of PI material, the substrate layer 22 has excellent mechanical properties and high tensile strength. Therefore, the back film 20 composed of the substrate layer 22 can be disposed on the non-display surface B side of the foldable display panel or curved display panel, and thus applied in foldable display products or curved display products. The PI material substrate layer 22 can improve the durability of the foldable display panel or curved display panel, and can avoid problems such as the foldable display panel or curved display panel falling off.

[0073] In some embodiments, the thickness of the substrate layer 22 can range from 25 μm to 75 μm.

[0074] For example, the thickness of the substrate layer 22 can be, for example, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm or 75μm, etc., and this disclosure does not limit it.

[0075] For example, the thickness of the substrate layer 22 is in the range of 25μm to 75μm, which can ensure that the substrate layer 22 has suitable support performance, thereby providing effective support for the display panel 30. At the same time, the thickness of the substrate layer 22 is in the range of 25μm to 75μm, which can also make the substrate layer 22 have a suitable thickness, realize the flexible design and thin design of the display module 100, and when the substrate layer 22 is laser-cut, the laser can completely cut the substrate layer 22, avoiding any impact on the substrate layer 22.

[0076] In some embodiments, the elastic modulus of the material of the protective layer 24 is greater than or equal to the elastic modulus of the material of the substrate layer 22.

[0077] For example, the material of the protective layer 24 can be more rigid than the substrate layer 22, so that the protective layer 24 can provide better support for the substrate layer 22 and better protect the substrate layer 22.

[0078] In some embodiments, under conditions where the temperature range is 10°C to 40°C, the elastic modulus of the material of the protective layer 24 is in the range of 3 GPa to 4 GPa.

[0079] For example, at temperatures of 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C, the elastic modulus of the material of the protective layer 24 can be, for example, 3 GPa, 3.1 GPa, 3.2 GPa, 3.3 GPa, 3.4 GPa, 3.5 GPa, 3.6 GPa, 3.7 GPa, 3.8 GPa, 3.9 GPa, or 4 GPa, etc., and this disclosure does not impose any limitations.

[0080] For example, the material of the protective layer 24 can be PET, or it can be other materials or combinations thereof with an elastic modulus in the range of 3 GPa to 4 GPa. This disclosure does not impose any limitations. The protective layer 24 is used to protect the substrate layer 22 and provide support for the substrate layer 22.

[0081] In some embodiments, the thickness of the protective layer 24 ranges from 25 μm to 150 μm.

[0082] For example, the thickness of the protective layer 24 can be, for example, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm or 150μm, etc., and this disclosure does not limit it.

[0083] In some embodiments, as shown in FIG3, the back film 20 includes a first adhesive layer 21, a substrate layer 22, a second adhesive layer 23, and a protective layer 24 stacked together. The elastic modulus of the material of the first adhesive layer 21 ranges from 0.05 MPa to 0.5 MPa, and the thickness of the first adhesive layer 21 ranges from 10 μm to 30 μm. The elastic modulus of the material of the substrate layer 22 ranges from 2 GPa to 3 GPa, and the thickness of the substrate layer 22 ranges from 25 μm to 75 μm. The elastic modulus of the material of the second adhesive layer 23 ranges from 0.2 MPa to 1 MPa, and the thickness of the second adhesive layer 23 ranges from 10 μm to 30 μm. The elastic modulus of the material of the protective layer 24 ranges from 3 GPa to 4 GPa, and the thickness of the protective layer 24 ranges from 25 μm to 150 μm. A ball-dropping and pen-dropping test can be performed on the display module 100 including the back film 20. The comparison table of ball-dropping and pen-dropping tests is shown in the table below.

[0084] For example, the weight of the ball is 65g. The structure of the back film 20 is shown in Figure 1. This back film 20 is referred to as the PI material back film. When the ball falls on the planar area of ​​the display module 100 including the PI material back film, the height of the falling ball is 30cm to 45cm. If the height of the falling ball is greater than 45cm, the display module 100 will be damaged. When the ball falls on the bent area of ​​the display module 100 including the PI material back film, the height of the falling ball is 15cm to 25cm. If the height of the falling ball is greater than 25cm, the display module 100 will be damaged. The structure of the back film 20 is shown in Figure 3. This back film 20 is referred to as the back film of this disclosure. When the ball falls on the planar area of ​​the display module 100 including the back film of this disclosure, the height of the falling ball is greater than 60cm. When the ball falls on the bent area of ​​the display module 100 including the back film of this disclosure, the height of the falling ball is greater than 30cm.

[0085] For example, the structure of the back film 20 is shown in Figure 1. When a pen falls on the planar area of ​​the display module 100 including the PI material back film, the pen's height is 30cm to 60cm. If the pen's height exceeds 60cm, the display module 100 will be damaged. When a pen falls on the bent area of ​​the display module 100 including the PI material back film, the pen's height is 15cm to 35cm. If the pen's height exceeds 35cm, the display module 100 will be damaged. The structure of the back film 20 is shown in Figure 3. When a pen falls on the planar area of ​​the display module 100 including the back film of this disclosure, the pen's height is greater than 60cm. When a pen falls on the bent area of ​​the display module 100 including the back film of this disclosure, the pen's height is greater than 30cm.

[0086] As can be seen from the above, the back film 20 provided by the embodiments of this disclosure improves the pressure resistance of the display module 100. That is, the back film 20 provided by the embodiments of this disclosure can withstand greater pressure. Therefore, the back film 20 provided by the embodiments of this disclosure can release the pressure applied to the display panel 30 by the first adhesive layer 21 in the first time. A small portion of the pressure that is not released can be transmitted to the second adhesive layer 23, which releases it. The first adhesive layer 21 and the second adhesive layer 23 work together to effectively prevent cracks from being pressed into the area where the display panel 30 is bonded. This effectively avoids problems such as bright lines and abnormal display functions after the display panel 30 is stretched, making the display module 100 more reliable and durable in reliability verification.

[0087] On the other hand, a display module 100 is provided, as shown in FIG1 and referring to FIG3, including a display panel 30 and a back film 20 as described above. The back film 20 is disposed on the non-display surface B side of the display panel 30, and the first adhesive layer 21 of the back film 20 is attached to the display panel 30.

[0088] For example, when the driver chip 200 is bonded to the display panel 30 using COF technology, the large pressure applied to the display panel 30 can be transmitted to the back film 20. This pressure can be released through the back film 20, which can effectively prevent cracks from being pressed into the area where the display panel 30 is bonded. This avoids problems such as bright lines appearing on the display panel 30 after it is stretched, making the display module 100 more reliable and durable in reliability verification.

[0089] In another aspect, embodiments of this disclosure also provide another display module 100, as shown in FIG4, including a display panel 30 and a first adhesive layer 21 and a substrate layer 22 of the back film 20 as described above; the first adhesive layer 21 and the substrate layer 22 are located on the non-display surface B side of the display panel 30, and the first adhesive layer 21 is attached to the display panel 30.

[0090] For example, the back film 20 includes a first adhesive layer 21, a substrate layer 22, a second adhesive layer 23, and a protective layer 24. When bonding the driver chip 200, it can effectively prevent cracks from being pressed into the area near the bonding area on the display panel 30, thereby avoiding problems such as bright lines appearing on the display panel 30 after being stretched, making the display module 100 more reliable and durable in reliability verification.

[0091] After the driver chip 200 is bonded, the second adhesive layer 23 and the protective layer 24 in the back film 20 are removed, which can reduce the thickness of the display module 100 and achieve a thinner design. At the same time, the materials of the first adhesive layer 21 and the substrate layer 22 have a small elastic modulus, excellent mechanical properties and high tensile strength. Therefore, the first adhesive layer 21 and the substrate layer 22 can be disposed on the non-display surface B side of the foldable display panel or the curved display panel, and thus applied in foldable display products or curved display products. The first adhesive layer 21 and the substrate layer 22 can improve the durability of the foldable display panel or the curved display panel and can avoid problems such as the foldable display panel or the curved display panel falling off.

[0092] In some embodiments, as shown in FIG4, the display module 100 further includes a support plate 10, which is located on the side of the substrate layer 22 away from the display panel 30.

[0093] For example, the support plate 10 is disposed on the side of the back film 20 away from the display panel 30. The support plate 10 provides support for the display module 100 and ensures the stability and safety of the display module 100 structure.

[0094] On the other hand, as shown in Figures 1 and 4, a display device 1000 is provided, including a display module 100 as described above and a driver chip 200, wherein the driver chip 200 is used to drive the display module 100 to display.

[0095] By way of example, display device 1000 can be any device that displays either moving (e.g., video) or stationary (e.g., still image), and whether it is text or image. Display device 1000 includes, but is not limited to, televisions, mobile phones, wearable devices, personal digital assistants (PDAs), augmented reality (AR) devices, virtual reality (VR) devices, handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, camcorders, game consoles, clocks, calculators, television monitors, flat panel displays, computer monitors, in-vehicle displays (e.g., odometer displays, etc.), navigators, cockpit controllers and / or displays, displays of camera views (e.g., displays of rearview cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0096] In some embodiments, the driver chip 200 may include a memory, a power module, etc., and achieve power supply and signal input / output functions through additional wires, signal lines, etc.

[0097] In other embodiments, the driver chip 200 may also include hardware circuitry and computer-executable code. The hardware circuitry may include conventional very-large-scale integrated circuits (VLSI) or gate arrays, as well as existing semiconductors or other discrete components such as logic chips, transistors, etc.; the hardware circuitry may also include field-programmable gate arrays, programmable array logic, programmable logic devices, etc.

[0098] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0099] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

A back film, applied to a display module, comprising: A first adhesive layer, a substrate layer, a second adhesive layer, and a protective layer are stacked together; Wherein, the elastic modulus of the material of the second adhesive layer is less than the elastic modulus of the material of the substrate layer, and the elastic modulus of the material of the first adhesive layer is less than or equal to the elastic modulus of the material of the second adhesive layer. According to claim 1, the backsheet, wherein, Under temperature conditions ranging from 10℃ to 40℃, the elastic modulus of the first adhesive layer is in the range of 0.05MPa to 0.5MPa. The backsheet according to claim 1 or 2, wherein, Under temperature conditions ranging from 10℃ to 40℃, the elastic modulus of the second adhesive layer ranges from 0.2MPa to 1MPa. The backsheet according to any one of claims 1 to 3, wherein, The thickness of the first adhesive layer ranges from 10μm to 30μm. The backsheet according to any one of claims 1 to 4, wherein, The thickness of the second adhesive layer ranges from 10μm to 30μm. The backsheet according to any one of claims 1 to 5, wherein, The thickness of the first adhesive layer is equal to the thickness of the second adhesive layer. The backsheet according to any one of claims 1 to 6, wherein, Under a temperature range of 10℃ to 40℃, the elastic modulus of the substrate layer material ranges from 2GPa to 3GPa. The backsheet according to any one of claims 1 to 7, wherein, The thickness of the substrate layer ranges from 25 μm to 75 μm. The backsheet according to any one of claims 1 to 8, wherein, The elastic modulus of the material of the protective layer is greater than or equal to the elastic modulus of the material of the substrate layer. The backsheet according to any one of claims 1 to 9, wherein, Under temperature conditions ranging from 10°C to 40°C, the elastic modulus of the material of the protective layer ranges from 3 GPa to 4 GPa. The backsheet according to any one of claims 1 to 10, wherein, The thickness of the protective layer ranges from 25 μm to 150 μm. A display module, comprising: Display panel; The back film as described in any one of claims 1 to 11, wherein the back film is disposed on the non-display side of the display panel, and the first adhesive layer of the back film is attached to the display panel. A display module, comprising: Display panel; The first adhesive layer and the substrate layer of the back film as described in any one of claims 1 to 11; The first adhesive layer and the substrate layer are located on the non-display side of the display panel, and the first adhesive layer is attached to the display panel. The display module according to claim 13 further includes a support plate, the support plate being located on the side of the substrate layer away from the display panel. A display device, comprising: The display module as described in claim 13 or 14; A driver chip is used to drive the display module to display.

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