Bonding structure, bonding structure preparation method and display device

Abstract

This invention discloses a bonding structure, a bonding structure fabrication method, and a display device. The bonding structure includes: a first bonding element, comprising a first substrate and a first bonding layer disposed on the first substrate, the first bonding layer including a first bonding portion; a second bonding element, comprising a second substrate and a second bonding layer disposed on the second substrate, the second bonding layer including a second bonding portion; the first bonding portion and the second bonding portion are bonded; a first anti-expansion layer is disposed on the side of the first bonding portion opposite to the second bonding portion, the thermal expansion coefficient of the first anti-expansion layer being less than the thermal expansion coefficient of the first substrate; and / or, a second anti-expansion layer is disposed on the side of the second bonding portion opposite to the first bonding portion, the thermal expansion coefficient of the second anti-expansion layer being less than the thermal expansion coefficient of the second substrate. The expansion deformation of the first and second anti-expansion layers at high temperatures is relatively small, improving the alignment accuracy and stability of the bonding between the first and second bonding layers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic products, and particularly relates to a bonding structure, a bonding structure preparation method and a display device. BACKGROUND

[0002] With the progress of science and technology, digital display devices such as smart phones and tablet computers are widely used. Among them, the display screen is an indispensable interface for interpersonal communication in these display devices. For example, an OLED (Organic Light Emitting Diode) display panel has the advantages of self-luminous, energy saving, bendable, good flexibility, etc. Moreover, the display device for realizing display does not need a backlight source, has the characteristics of fast response and good display effect, and is widely used in terminal products such as smart phones and tablet computers.

[0003] The bonding process is to realize the electrical connection between the array module and the FPC (Flexible Printed Circuit) through the ACF (Anisotropic Conductive Film). Since the working temperature during the bonding process is high, the existing film layer structure is prone to thermal expansion and deformation, resulting in the problem of deviation of the bonding layer.

[0004] Therefore, there is an urgent need for a new bonding structure, a bonding structure preparation method and a display device. SUMMARY

[0005] The bonding structure, the bonding structure preparation method and the display device provided by the embodiments of the present application have the advantages that since the thermal expansion coefficient of the first anti-expansion layer is less than the thermal expansion coefficient of the first substrate, and the thermal expansion coefficient of the second anti-expansion layer is less than the thermal expansion coefficient of the second substrate, the expansion and deformation amount of the first anti-expansion layer and the second anti-expansion layer at high temperature is relatively small, thereby reducing the risk of deviation of the first bonding layer and the second bonding layer, and improving the alignment accuracy and stability of the bonding of the first bonding layer and the second bonding layer.

[0006] The embodiments of the present application provide a bonding structure, which comprises: a first bonding member comprising a first substrate and a first bonding layer arranged on the first substrate, the first bonding layer comprising a first bonding part; a second bonding member comprising a second substrate and a second bonding layer arranged on the second substrate, the second bonding layer comprising a second bonding part; the first bonding part and the second bonding part are bonded; a first anti-expansion layer is arranged on the side of the first bonding part away from the second bonding part, and the thermal expansion coefficient of the first anti-expansion layer is less than the thermal expansion coefficient of the first substrate; and / or a second anti-expansion layer is arranged on the side of the second bonding part away from the first bonding part, and the thermal expansion coefficient of the second anti-expansion layer is less than the thermal expansion coefficient of the second substrate.

[0007] According to an aspect of the present application, the first anti-expansion layer covers the first bonding part in orthographic projection on the first bonding layer; and the second anti-expansion layer covers the second bonding part in orthographic projection on the second bonding layer.

[0008] According to an aspect of the present application, the first bonding member further comprises a support layer arranged on the side of the first substrate away from the first bonding layer, the first anti-expansion layer and the support layer are arranged on the side surface of the first substrate away from the first bonding layer, and a gap is arranged between the first anti-expansion layer and the support layer.

[0009] According to an aspect of the present application, the first bonding layer comprises a first extension part extending outward relative to the first substrate, part or all of the first extension part forms the first bonding part, and the first anti-expansion layer is arranged on the side surface of the first extension part away from the first bonding member; and / or, the second bonding layer comprises a second extension part extending outward relative to the second substrate, part or all of the second extension part forms the second bonding part, and the second anti-expansion layer is arranged on the side surface of the second extension part away from the first bonding member.

[0010] According to an aspect of the present application, the second bonding member further comprises a conductive layer arranged on the side of the second substrate away from the second bonding layer and a first insulating protective layer arranged on the side of the conductive layer away from the second substrate; the orthographic projection of the conductive layer and the first insulating protective layer on the second substrate coincides with the second substrate, so that the side surface of the second substrate, the conductive layer and the first insulating protective layer close to the second extension part and the second extension part form a hollow area, and the second anti-expansion layer is arranged in the hollow area.

[0011] According to an aspect of the present application, the side surface of the second substrate close to the second extension part and the second extension part form a hollow area, and the second anti-expansion layer is arranged in the hollow area; preferably, the orthographic projection of the second anti-expansion layer on the second extension part coincides with the second extension part.

[0012] According to an aspect of the present application, the coefficient of thermal expansion of the first anti-expansion layer or the second anti-expansion layer is 1.5×10 -6 / ℃~3.0×10 -6 / ℃; preferably, the first anti-expansion layer comprises a high polymer composite; preferably, further comprising a conductive adhesive, and the first bonding part and the second bonding part are electrically connected through the conductive adhesive; preferably, in the direction perpendicular to the plane where the first substrate is located, the thickness of the conductive adhesive is 1 μm~12 μm.

[0013] The application further provides a bonding structure preparation method, comprising the following steps: providing a first bonding member, wherein the first bonding member comprises a first substrate and a first bonding layer formed on the first substrate, and the first bonding layer comprises a first bonding part; providing a second bonding member, wherein the second bonding member comprises a second substrate and a second bonding layer formed on the second substrate, and the second bonding layer comprises a second bonding part; forming a first anti-expansion layer on a side of the first bonding part away from the second bonding part, wherein the first anti-expansion layer has a thermal expansion coefficient smaller than that of the first substrate; and / or forming a second anti-expansion layer on a side of the second bonding part away from the first bonding part, wherein the second anti-expansion layer has a thermal expansion coefficient smaller than that of the second substrate; and pressing the first anti-expansion layer and / or the second anti-expansion layer by a pressure head at a preset temperature to bond the first bonding member and the second bonding member.

[0014] According to another aspect of the application, the step of forming the second anti-expansion layer on a side of the second bonding part away from the first bonding part comprises: forming a conductive layer on a side of the second substrate away from the second bonding layer; forming a first insulating protective layer on a side of the conductive layer away from the second substrate; etching the second substrate, the conductive layer and the first insulating protective layer to form a hollow area and expose part of the second bonding layer; and forming the second anti-expansion layer in the hollow area.

[0015] According to still another aspect of the application, the application further provides a display device comprising the bonding structure.

[0016] Compared with the prior art, the bonding structure provided by the application comprises a first bonding member and a second bonding member, and a first anti-expansion layer is arranged on a side of the first bonding part away from the second bonding part, and / or a second anti-expansion layer is arranged on a side of the second bonding part away from the first bonding part, so that the first anti-expansion layer and / or the second anti-expansion layer can be pressed by a hot pressure head during the bonding process of the first bonding member and the second bonding member. Since the thermal expansion coefficient of the first anti-expansion layer is smaller than that of the first substrate, and the thermal expansion coefficient of the second anti-expansion layer is smaller than that of the second substrate, the deformation amount of the first anti-expansion layer and the second anti-expansion layer at high temperature is relatively small, thereby reducing the risk of deviation of the first bonding layer and the second bonding layer, and improving the alignment accuracy and stability of the bonding of the first bonding layer and the second bonding layer. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0018] Figure 1 is a structural schematic diagram of a display device provided by an embodiment of the present application;

[0019] Figure 2 is a display device provided by an embodiment of the present application Figure 1 is a film layer structure diagram at A-A in the display device;

[0020] Figure 3 is a display device provided by another embodiment of the present application Figure 1 is a film layer structure diagram at A-A in the display device;

[0021] Figure 4 is a display device provided by yet another embodiment of the present application Figure 1 is a film layer structure diagram at A-A in the display device;

[0022] Figure 5 is a display device provided by an embodiment of the present application Figure 1 is a film layer structure diagram at B-B in the display device;

[0023] Figure 6 is a display device provided by yet another embodiment of the present application Figure 1 is a film layer structure diagram at A-A in the display device;

[0024] Figure 7 is a flow chart of a bonding structure preparation method provided by an embodiment of the present application.

[0025] In the drawings:

[0026] 1-first bonding member; 11-first substrate; 12-first bonding layer; 13-supporting layer; 14-encapsulation layer; 2-second bonding member; 21-second substrate; 22-second bonding layer; 23-conductive layer; 24-first insulating protective layer; 25-tin layer; 26-ink layer; 27-second insulating protective layer; 3-first anti-expansion layer; 4-conductive adhesive; 5-second anti-expansion layer. DETAILED DESCRIPTION

[0027] The features and exemplary embodiments of the various aspects of the present application will be described in detail below with reference to the figures. To make the present application more clear and comprehensive, the present application will be further described in detail below with reference to the figures and specific embodiments. It should be understood that the specific embodiments described herein are configured only to explain the present application and are not configured to limit the present application. The present application can be implemented without some of the specific details by those skilled in the art. The following description of the embodiments is merely provided to provide a better understanding of the present application by showing examples of the present application.

[0028] It should be noted that the relative terms such as first and second, etc., are used herein only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a list of elements does not only include those elements, but also includes other elements not explicitly listed, or further includes elements inherent in such a process, method, article or apparatus. Without more limitations, the elements defined by the statement "comprising" do not exclude the presence of additional identical elements in the process, method, article or apparatus including the elements.

[0029] It should be understood that, when describing the structure of a component, when one layer, one region is referred to as being "on" or "above" another layer, another region, it can mean being directly on or above the other layer, the other region, or other layers or regions can be included therebetween. Moreover, if the component is flipped, the one layer, the one region will be "under" or "below" the other layer, the other region.

[0030] Various modifications and changes can be made to the present application without departing from the spirit or scope of the present application, which will be apparent to those skilled in the art. Accordingly, the present application is intended to cover all modifications and changes that fall within the scope of the corresponding claims (technical solutions claimed) and their equivalents. It should be noted that the embodiments provided by the embodiments of the present application can be combined with each other without contradiction.

[0031] In the related art, in order to realize the bonding connection between the first bonding layer 12 of the first bonding member 1 and the second bonding layer 22 of the second bonding member 2, the required bonding process temperature is high, that is, the first substrate 11 and / or the second substrate 21 need to be pressed by a hot press head in a high environment temperature to realize the conductive connection of the first bonding layer 12 and the second bonding layer 22. Since the material used for the first substrate 11 and the second substrate 21 has a high thermal expansion coefficient, a large expansion deformation will occur at high temperature, and then the bonding layer arranged on the first substrate 11 and the second substrate 21 will be deviated.

[0032] In order to solve the above problems, the embodiments of the present application provide a bonding structure, a bonding structure preparation method and a display device, which will be described below with reference to the accompanying drawings Figures 1 to 7 The embodiments of the bonding structure, the bonding structure preparation method and the display device will be described.

[0033] Please refer to Figures 1 to 4 , Figure 1 is a structural schematic diagram of a display device provided by an embodiment of the present application; Figure 2 is a bonding structure provided by an embodiment of the present application; Figure 1 is a film layer structure diagram at A-A in the bonding structure; Figure 3 is a bonding structure provided by another embodiment of the present application; Figure 1 is a film layer structure diagram at A-A in the bonding structure; Figure 4 is a bonding structure provided by still another embodiment of the present application; Figure 1 is a film layer structure diagram at A-A in the bonding structure.

[0034] The bonding structure provided by the embodiments of the present application comprises: a first bonding member 1 comprising a first substrate 11 and a first bonding layer 12 arranged on the first substrate 11, the first bonding layer 12 comprising a first bonding part; a second bonding member 2 comprising a second substrate 21 and a second bonding layer 22 arranged on the second substrate 21, the second bonding layer 22 comprising a second bonding part; the first bonding part and the second bonding part are bonded; a first anti-expansion layer 3 is arranged on the side of the first bonding part away from the second bonding part, and the thermal expansion coefficient of the first anti-expansion layer 3 is less than the thermal expansion coefficient of the first substrate 11; and / or a second anti-expansion layer 5 is arranged on the side of the second bonding part away from the first bonding part, and the thermal expansion coefficient of the second anti-expansion layer 5 is less than the thermal expansion coefficient of the second substrate 21.

[0035] The bonding structure provided by the embodiment of the present application comprises a first bonding member 1 and a second bonding member 2, and the first anti-expansion layer 3 is arranged on the side of the first bonding part away from the second bonding part, and / or the second anti-expansion layer 5 is arranged on the side of the second bonding part away from the first bonding part, so that the first anti-expansion layer 3 and / or the second anti-expansion layer 5 can be pressed by a hot press head during the bonding process of the first bonding member 1 and the second bonding member 2. Since the thermal expansion coefficient of the first anti-expansion layer 3 is less than the thermal expansion coefficient of the first substrate 11, and the thermal expansion coefficient of the second anti-expansion layer 5 is less than the thermal expansion coefficient of the second substrate 21, the expansion deformation amount of the first anti-expansion layer 3 and the second anti-expansion layer 5 at high temperature is relatively small, thereby reducing the risk of deviation of the first bonding layer 12 and the second bonding layer 22, and improving the alignment accuracy and stability of the bonding of the first bonding layer 12 and the second bonding layer 22.

[0036] The first bonding part can be understood as the part of the first bonding layer 12 extending outward to be bonded to the second bonding member 2, including but not limited to a gold finger, a bonding pad and the like.

[0037] Optionally, the first bonding member 1 can be a FPC (Flexible Printed Circuit, flexible circuit board), which can be made of polyimide or polyester film and the like, and the second bonding member 2 can be a substrate of a display device, or the first bonding member 1 is a substrate, and the second bonding member 2 is a flexible circuit board, or the first bonding member 1 and the second bonding member 2 are both flexible circuit boards, without special limitation. The substrate can be a hard substrate such as a glass substrate, or a flexible substrate, which can be made of polyimide, polystyrene, polyethylene terephthalate, poly-p-xylylene, polyether sulfone or polyethylene naphthalate. The substrate is mainly used to support the devices arranged thereon. The substrate can be a single-layer substrate to save cost, or a double-layer substrate to improve water and oxygen barrier performance.

[0038] Of course, the first bonding member 1 or the second bonding member 2 can also be a COF (Chip flexible printed circuit, flexible packaging substrate), which refers to a packaging type flexible substrate that has not yet been assembled with a chip, component. In the process of chip packaging, it plays a role in carrying chips, circuit communication, and insulating support, especially for physical protection of chips, improvement of signal transmission rate, signal fidelity, impedance matching, stress relief, and heat dissipation and moisture resistance. Compared with FPC, the COF flexible packaging substrate has the following characteristics: the COF flexible packaging substrate can carry chips, while the FPC cannot carry chips and can only be used as a medium for signal transmission of electronic products; the COF flexible packaging substrate is smaller in size, more precise in circuit manufacturing, and higher in wiring density; the COF flexible packaging substrate has higher requirements for the performance of conductive and insulating reliability, heat resistance, moisture resistance, elastic modulus, and uniformity of the thickness of the board than the FPC.

[0039] The structure of the second bonding member 2 using the COF is shown in Figure 6 A tin layer 25 and an ink layer 26 are stacked on the side of the second bonding layer 22 away from the second substrate 21.

[0040] It should be noted that the first anti-expansion layer 3 can be provided only on the side of the first bonding portion away from the second bonding portion, as shown in Figure 3 The second anti-expansion layer 5 can be provided only on the side of the second bonding portion away from the first bonding portion, as shown in Figure 4 , or the first anti-expansion layer 3 can be provided on the side of the first bonding portion away from the second bonding portion and the second anti-expansion layer 5 can be provided on the side of the second bonding portion away from the first bonding portion, as shown in Figure 2 .

[0041] The first anti-expansion layer 3 is provided on the side of the first bonding portion away from the second bonding portion, specifically, the first anti-expansion layer 3 can be directly attached to the surface of the side of the first bonding portion away from the second bonding portion, or can be provided on the surface of the side of the first substrate 11 away from the second bonding member 2, without special limitation. Similarly, the second anti-expansion layer 5 can be directly attached to the surface of the side of the second bonding portion away from the first bonding portion, or can be provided on the surface of the side of the second substrate 21 away from the first bonding portion, as long as the low expansion amount of the first anti-expansion layer 3 and the second anti-expansion layer 5 at high temperature can be used to reduce the risk of deviation of the bonding layer.

[0042] Optionally, the first anti-expansion layer 3 can be provided on the surface of the side of the first substrate 11 away from the first bonding portion, that is, the first substrate 11 is provided between the first anti-expansion layer 3 and the first bonding portion, and the thermal expansion coefficient of the first anti-expansion layer 3 is less than the thermal expansion coefficient of the first substrate 11, so as to ensure that the expansion deformation amount of the first anti-expansion layer 3 is relatively small when it is heated and pressed.

[0043] The second anti-expansion layer 5 can be directly attached to the side surface of the second bonding portion away from the first bonding portion, that is, no second substrate 21 is arranged between the second anti-expansion layer 5 and the second bonding portion, and specifically, part of the second substrate 21 can be removed to expose the second bonding portion, that is, the second anti-expansion layer 5 is used to replace the removed part of the second substrate 21. Since the thermal expansion coefficient of the second anti-expansion layer 5 is smaller than that of the second substrate 21, using the second anti-expansion layer 5 to replace the removed part of the second substrate 21 can also reduce the risk of deformation and deviation of the second bonding portion by using the low expansion deformation amount of the second anti-expansion layer 5 at high temperature.

[0044] The inventor has found through experimental research that the process temperature of the bonding process is usually 120-130°C, and the thermal expansion coefficients of the first anti-expansion layer 3 and the second anti-expansion layer 5 are 1.5x10 -6 / ℃-3.0x10 -6 / ℃, and the expansion of the first anti-expansion layer 3 and the second anti-expansion layer 5 will not affect the first bonding layer 12 and the second bonding layer 22. In addition, materials with thermal expansion coefficients within the above range are easy to obtain, and the first anti-expansion layer 3 and the second anti-expansion layer 5 can comprise high polymer composite materials, for example, the first anti-expansion layer 3 and the second anti-expansion layer 5 can be made of polyethylene propylene and the like.

[0045] In some optional embodiments, the orthographic projection of the first anti-expansion layer 3 on the first bonding layer 12 covers the first bonding portion, and the orthographic projection of the second anti-expansion layer 5 on the second bonding layer 22 covers the second bonding portion. Specifically, the shape and size of the first anti-expansion layer 3 can match the first bonding portion to ensure the uniformity of the stress of the first bonding portion when the pressure head is pressed, and the shape and size of the second anti-expansion layer 5 can also match the second bonding portion.

[0046] In some optional embodiments, the first bonding member 1 further comprises a support layer 13 arranged on the side of the first substrate 11 away from the first bonding layer 12, and the first anti-expansion layer 3 and the support layer 13 are arranged on the side surface of the first substrate 11 away from the first bonding layer 12, and a gap is arranged between the first anti-expansion layer 3 and the support layer 13.

[0047] The support layer 13 is a support material, and is usually made of PI (Polyimide, polyimide) material, which has the properties of high temperature resistance and good stability, and is suitable for making high temperature pressure sensitive adhesive. Optionally, the support layer 13 comprises a heat dissipation layer and a foam layer arranged in layers, the heat dissipation layer is usually made of graphene, metal or the like to achieve good heat dissipation function, and the foam layer can be made of foam to achieve cushioning function.

[0048] In the embodiment, the first anti-expansion layer 3 is arranged on the side of the first substrate 11 away from the first bonding layer 12, and a gap is arranged between the first anti-expansion layer 3 and the support layer 13 to avoid interference between the first anti-expansion layer 3 and the support layer 13, that is, the support layer 13 is arranged to avoid interference, thereby providing a space for the first anti-expansion layer 3. In the embodiment, the space for the first anti-expansion layer 3 is originally used to arrange the support layer 13, and in the embodiment, the space for the first anti-expansion layer 3 is obtained by cutting or directly reducing the size of the support layer 13. In the embodiment, the first anti-expansion layer 3 is arranged on the side of the first substrate 11 away from the first bonding layer 12, that is, the first anti-expansion layer 3 does not directly contact the first bonding layer 12. However, since the expansion deformation amount of the first anti-expansion layer 3 is relatively small, and the first anti-expansion layer 3 can play a certain heat insulation role, the heat received by the first substrate 11 is reduced, thereby reducing the expansion deformation amount of the first substrate 11, and avoiding the problem of deviation of the first bonding layer 12. Optionally, an encapsulation layer 14 can also be arranged on the surface of the first anti-expansion layer 3 which is not covered by the first bonding layer 12 to realize the insulation of the first bonding layer 12.

[0049] In some optional embodiments, the first bonding layer 12 includes a first extension portion extending outward relative to the first substrate 11, and part or all of the first extension portion forms a first bonding portion. The first anti-expansion layer 3 is arranged on the side surface of the first extension portion away from the second bonding member 2.

[0050] In the embodiment, there is no first substrate 11 between the first anti-expansion layer 3 and the first extension portion. Part of the first substrate 11 can be removed to expose the first bonding portion, that is, the first anti-expansion layer 3 is used to replace the removed part of the first substrate 11. The expansion amount of the first substrate 11 does not affect the first bonding layer 12.

[0051] And / or, the second bonding layer 22 includes a second extension portion extending outward relative to the second substrate 21, and part or all of the second extension portion forms a second bonding portion. The second anti-expansion layer 5 is arranged on the side surface of the second extension portion away from the first bonding member 1.

[0052] Similarly, the second extension portion of the second bonding layer 22 can be formed by removing part of the second substrate 21 to expose part of the second bonding layer 22. In the embodiment, the second anti-expansion layer 5 is directly arranged on the side surface of the second extension portion of the second bonding layer 22, that is, there is no second substrate 21 between the second anti-expansion layer 5 and the second extension portion. The expansion amount of the second substrate 21 does not affect the second bonding layer 22, thereby further improving the alignment accuracy when the second bonding layer 22 and the first bonding layer 12 are bonded.

[0053] In some optional embodiments, the second bonding member 2 further includes a conductive layer 23 disposed on the side of the second substrate 21 opposite to the second bonding layer 22 and a first insulating protective layer 24 disposed on the side of the conductive layer 23 opposite to the second substrate 21; the orthographic projections of the conductive layer 23 and the first insulating protective layer 24 on the second bonding layer 22 and the orthographic projections of the second substrate 21 on the second bonding layer 22 coincide, so that a hollow area is formed between the side of the second substrate 21, the conductive layer 23, the first insulating protective layer 24 near the second extension and the second extension, and the second anti-expansion layer 5 is disposed in the hollow area.

[0054] The hollow area specifically refers to the area formed by etching away part of the second substrate 21, the conductive layer 23 and the first insulating protective layer 24, which is used to accommodate the second anti-expansion layer 5.

[0055] It should be noted that when the second bonding component 2 is a flexible circuit board, the conductive layer 23 can be used to set conductive components or traces. Optionally, the conductive layer 23, the first bonding layer 12, and the second bonding layer 22 are all made of metal materials with good conductivity such as copper, silver, or titanium aluminum titanium.

[0056] Optionally, a second insulating protective layer 27 may also be provided on the side of the second bonding layer 22 opposite to the second substrate 21.

[0057] Please see Figure 6 In some optional embodiments, a hollow area is formed between the side of the second substrate 21 near the second extension and the second extension, and the second anti-expansion layer 5 is disposed in the hollow area; it is understood that in this embodiment, the side of the second substrate 21 away from the second bonding layer 22 may not be provided with other film layers, so that the second anti-expansion layer 5 can be disposed flush with the second substrate 21.

[0058] Optionally, the orthographic projection of the second anti-expansion layer 5 on the second extension coincides with the second extension, that is, the second anti-expansion layer 5 can just cover the second extension, so as to block the heat from the side of the second anti-expansion layer 5 away from the second extension during bonding.

[0059] Please see Figure 5 In some alternative embodiments, the bonding structure further includes conductive adhesive 4, through which the first bonding layer 12 and the opposing second bonding layer 22 are electrically connected.

[0060] The conductive adhesive 4 can specifically be ACF (Anisotropic Conductive Film), which mainly consists of two parts: a resin adhesive and conductive particles. Besides its functions of moisture resistance, heat resistance, and insulation, the resin adhesive primarily serves to fix the relative positions of the first bonding layer 12 and the second bonding layer 22, and to provide a compressive force to maintain the contact area between the first bonding layer 12, the second bonding layer 22, and the conductive particles. The conductive particles mainly consist of metal powder or polymer plastic spheres coated with metal. Commonly used metal powders include nickel, gold, nickel-plated gold, silver, and tin alloys.

[0061] When the conductive adhesive 4 is ACF adhesive, in order to make the ACF adhesive conductive, a hot press head is needed to press the anti-expansion layer 3 at a higher preset temperature so that the ACF adhesive can conduct under heat and force.

[0062] Optionally, the thickness of the conductive adhesive 4 is 1 μm to 12 μm in the direction perpendicular to the plane of the first bonding member 1.

[0063] Please see Figure 7 The present invention also provides a method for preparing a bonding structure, comprising the following steps:

[0064] S110: Provide a first bonding element 1, the first bonding element 1 including a first substrate 11 and a first bonding layer 12 formed on the first substrate 11, the first bonding layer 12 including a first bonding portion;

[0065] S120: A second bonding element 2 is provided, including a second substrate 21 and a second bonding layer 22 disposed on the second substrate 21, the second bonding layer 22 including a second bonding portion;

[0066] S130: A first anti-expansion layer 3 is formed on the side of the first bonding portion away from the second bonding portion, and the thermal expansion coefficient of the first anti-expansion layer 3 is less than the thermal expansion coefficient of the first substrate 11; and / or, a second anti-expansion layer 5 is formed on the side of the second bonding portion away from the first bonding portion, and the thermal expansion coefficient of the second anti-expansion layer 5 is less than the thermal expansion coefficient of the second substrate 21.

[0067] S140: At a preset temperature, pressure is applied to the first anti-expansion layer 3 and / or the second anti-expansion layer 5 by a pressure head to bond the first bonding member 1 and the second bonding member 2.

[0068] The bonding structure fabrication method provided in this embodiment of the invention provides a first anti-expansion layer 3 on the side of the first bonding portion away from the second bonding portion, and / or a second anti-expansion layer 5 on the side of the second bonding portion away from the first bonding portion. This reduces the expansion deformation of the anti-expansion layer 3 when the pressure head applies pressure to the anti-expansion layer 3 at a preset temperature. When performing the bonding process on the first bonding member 1 and the second bonding member 2, a hot pressure head can be used to press the first anti-expansion layer 3 and / or the second anti-expansion layer 5 together. Since the thermal expansion coefficient of the first anti-expansion layer 3 is less than that of the first substrate 11, and the thermal expansion coefficient of the second anti-expansion layer 5 is less than that of the second substrate 21, the expansion deformation of the first anti-expansion layer 3 and the second anti-expansion layer 5 at high temperatures is relatively small. This reduces the risk of misalignment of the first bonding layer 12 and the second bonding layer 22, and improves the alignment accuracy and stability of the bonding of the first bonding layer 12 and the second bonding layer 22.

[0069] In some alternative embodiments, the step of forming a second anti-expansion layer 5 on the side of the second bonding portion away from the first bonding portion includes: forming a conductive layer 23 on the side of the second substrate 21 away from the second bonding layer 22; forming a first insulating protective layer 24 on the side of the conductive layer away from the second substrate 21; etching the second substrate 21, the conductive layer 23 and the first insulating protective layer 24 to form a cutout area to expose a portion of the second bonding layer 22; and forming the second anti-expansion layer 5 in the cutout area.

[0070] It should be noted that, in this embodiment, in order to avoid the second substrate 21 affecting the position of the second bonding layer 22, a dry etching technique or a wet etching technique can be used to etch a portion of the second substrate 21, the conductive layer 23 and the first insulating protective layer 24 to form a hollow area, so as to expose a portion of the second bonding layer 22, and then form a second anti-expansion layer 5 in the hollow area.

[0071] It's important to note that the difference between dry etching and wet etching lies in the use of solvents or solutions for etching. Wet etching is a purely chemical reaction process, utilizing the chemical reaction between the solution and the pre-etching material to remove the unmasked portions. Its advantages include good selectivity, high repeatability, high production efficiency, simple equipment, and low cost. Dry etching, on the other hand, encompasses many types, including photoelectrolysis, vapor phase etching, and plasma etching. Its advantages include good anisotropy, high selectivity, good controllability, flexibility, and repeatability, safe operation on fine lines, easy automation, no chemical waste, no pollution introduced during the process, and high cleanliness. In this embodiment, either dry or wet etching can be selected based on the specific circumstances.

[0072] In this embodiment, laser etching or etching solution etching can be used.

[0073] Optionally, a pressure head is used to apply pressure to the first anti-expansion layer 3 and / or the second anti-expansion layer 5 to press the first bonding member 1 and the second bonding member 2 together, so that the first bonding layer 12 and the second bonding layer 22 of the first bonding member 1 are electrically connected. The preset temperature is 120℃~130℃, which can refer to the temperature of the pressure head. During the pressing process, the heat of the pressure head is conducted to the conductive adhesive 4 between the first bonding layer 12 and the second bonding layer 22 to make the conductive adhesive 4 conductive.

[0074] This invention also provides a display device including the bonding structure described in any of the above embodiments. The display panel provided by this invention has the technical effects of the substrate in any of the above embodiments. Explanations of structures and terms identical or corresponding to those in the above embodiments will not be repeated here.

[0075] The display device provided in this embodiment of the invention can be applied to mobile phones or any electronic product with display function, including but not limited to the following categories: televisions, laptops, desktop monitors, tablets, digital cameras, smart bracelets, smart glasses, in-vehicle displays, medical devices, industrial control equipment, touch interactive terminals, etc. This embodiment of the invention does not impose any special limitations on these.

[0076] The above are merely specific embodiments of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

[0077] It should also be noted that the exemplary embodiments mentioned in this invention describe methods or systems based on a series of steps or apparatus. However, this invention is not limited to the order of the steps described above; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

Claims

1. A bonding structure, characterized by, The first bonding member comprises a first substrate and a first bonding layer arranged on the first substrate, and the first bonding layer comprises a first bonding part. The second bonding member comprises a second substrate and a second bonding layer arranged on the second substrate, and the second bonding layer comprises a second bonding part, a conductive layer arranged on a side of the second substrate away from the second bonding layer, and a first insulating protective layer arranged on a side of the conductive layer away from the second substrate. The first bonding part and the second bonding part are bonded. A first anti-expansion layer is arranged on a side of the first bonding part away from the second bonding part, and a thermal expansion coefficient of the first anti-expansion layer is smaller than a thermal expansion coefficient of the first substrate; and / or A second anti-expansion layer is arranged on a side of the second bonding part away from the first bonding part, and a thermal expansion coefficient of the second anti-expansion layer is smaller than a thermal expansion coefficient of the second substrate. The first bonding layer comprises a first extension part extending outward relative to the first substrate, and part or all of the first extension part forms the first bonding part, and the first anti-expansion layer is arranged on a side surface of the first extension part away from the first bonding member; and the second bonding layer comprises a second extension part extending outward relative to the second substrate, and part or all of the second extension part forms the second bonding part, and the second anti-expansion layer is arranged on a side surface of the second extension part away from the first bonding member. The conductive layer and the first insulating protective layer are arranged on the second substrate, and a normal projection of the conductive layer and the first insulating protective layer on the second substrate coincides with the second substrate, so that a hollow region is formed between a side of the second extension part close to the second extension part and the second extension part, and the second anti-expansion layer is arranged in the hollow region. A normal projection of the first anti-expansion layer on the first bonding layer covers the first bonding part.

2. The bonding structure according to claim 1, wherein A normal projection of the second anti-expansion layer on the second bonding layer covers the second bonding part. The first bonding member further comprises a support layer arranged on a side of the first substrate away from the first bonding part, and the first anti-expansion layer and the support layer are arranged on a side surface of the first substrate away from the first bonding layer, and a gap is arranged between the first anti-expansion layer and the support layer.

3. The bonding structure according to claim 1 or 2, wherein A normal projection of the second anti-expansion layer on the second extension part coincides with the second extension part.

4. The bonding structure of claim 1, wherein The first anti-expansion layer or the second anti-expansion layer comprises a high polymer composite material.

5. The bonding structure of claim 1, wherein The coefficient of thermal expansion of the first or second anti-expansion layer is 1.5 x 10 -6 / °C to 3.0 x 10 -6 / °C.

6. The bonding structure of claim 1, wherein The bonding structure further comprises a conductive adhesive, and the first bonding part and the second bonding part are electrically connected through the conductive adhesive.

7. The bonding structure of claim 1, wherein In a direction perpendicular to a plane in which the first substrate is arranged, a thickness of the conductive adhesive is 1 μm to 12 μm.

8. The bonding structure of claim 7, wherein The method comprises the following steps:

9. A method for producing a bonding structure for producing the bonding structure according to any one of claims 1 to 8, characterized by, A first bonding member is provided, which comprises a first substrate and a first bonding layer formed on the first substrate, and the first bonding layer comprises a first bonding part. A second bonding member is provided, which comprises a second substrate and a second bonding layer arranged on the second substrate, and the second bonding layer comprises a second bonding part. ​ a first anti-expansion layer is formed on a side of the first bonding part away from the second bonding part, the first anti-expansion layer having a thermal expansion coefficient less than that of the first substrate; and / or a second anti-expansion layer is formed on a side of the second bonding part away from the first bonding part, the second anti-expansion layer having a thermal expansion coefficient less than that of the second substrate; at a preset temperature, the first anti-expansion layer and / or the second anti-expansion layer is pressed by a pressure head to bond the first bonding part and the second bonding part.

10. The method of claim 9, wherein the bonding structure is prepared by a method comprising: The step of forming the second anti-expansion layer on a side of the second bonding part away from the first bonding part comprises: ​ a conductive layer is formed on a side of the second substrate away from the second bonding layer; a first insulating protective layer is formed on a side of the conductive layer away from the second substrate; the second substrate, the conductive layer and the first insulating protective layer are etched to form a hollow region and expose part of the second bonding layer; the second anti-expansion layer is formed in the hollow region.

11. A display device comprising: A bonding structure comprising any one of claims 1 to 8.

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