Display backboard, display panel and preparation method of display panel

Abstract

The invention discloses a display back plate, a display panel and a preparation method of the display panel. The display back plate comprises a substrate and a release film, and a bonding pad is arranged on the first surface of the substrate; the release film is attached to the first surface of the substrate, a through hole is formed in the release film, and the bonding pad is located in the through hole. Through the scheme, the conductive adhesive film material can be effectively utilized, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display backplane, a display panel, and a method for preparing the display panel. Background Art

[0002] Micro-LED display is one of the cutting-edge development directions in the current display field, among which mass transfer is a key technology in Micro-LED display technology. Mass transfer is to transfer a huge number of Micro-LEDs in batches to the target display backplane to achieve the target backplane's luminous display.

[0003] In order to achieve normal display and light emission after Micro-LEDs are transferred in batches to the display backplane, it is necessary to electrically connect the P and N electrodes of the Micro-LEDs to the corresponding electrodes on the display backplane to achieve conduction of electrical signals and thus achieve light emission.

[0004] However, the cost of the current mass transfer process is still relatively high. Summary of the invention

[0005] The main technical problem solved by the present application is to provide a method for attaching a display backplane and a conductive adhesive film, so as to effectively utilize the conductive adhesive film material and reduce the cost.

[0006] In order to solve the above technical problems, a technical solution adopted in the present application is: providing a display back panel, including a substrate and a release film, the first surface of the substrate is provided with a soldering pad; the release film is attached to the first surface of the substrate, the release film is provided with a through hole, and the soldering pad is located in the through hole.

[0007] Preferably, the release film comprises a first release layer and a first adhesive layer which are stacked, and the through hole penetrates the first release layer and the first adhesive layer.

[0008] Preferably, the material of the first adhesive layer includes pressure-sensitive adhesive.

[0009] Preferably, the thickness of the first adhesive layer is 5-10 μm; and / or the thickness of the first release layer is 20-50 μm.

[0010] Preferably, the release film further includes a first protective layer, and the first protective layer is located on a side of the first release layer away from the first adhesive layer.

[0011] Preferably, the first protection layer covers the through hole.

[0012] Preferably, the cross section of the through hole parallel to the first release layer is circular or rectangular.

[0013] Preferably, the distance from the edge of the through hole to the edge of the pad inside the through hole and adjacent to the edge of the through hole is in the range of 10-20 μm.

[0014] In order to solve the above technical problems, another technical solution adopted by the present application is: providing a display panel: comprising the display backplane in any embodiment, a conductive adhesive film and a light-emitting element, wherein the conductive adhesive film is attached to the pad, wherein the orthographic projection of the through hole on the substrate covers the orthographic projection of the conductive adhesive film on the substrate, and the orthographic projection of the conductive adhesive film on the substrate at least partially overlaps with the pad. The light-emitting element is arranged on a side of the conductive adhesive film away from the pad, and the light-emitting element is electrically connected to the pad through the conductive adhesive film.

[0015] Preferably, the conductive adhesive film comprises a second adhesive layer and a second protective layer which are stacked, and the second adhesive layer is used for being attached to the pad.

[0016] To solve the above technical problems, another technical solution adopted in the present application is: providing a method for preparing a display panel, comprising: providing a substrate and a release film, wherein a solder pad is provided on the first surface of the substrate, and a through hole corresponding to the solder pad is provided on the release film; attaching the release film to the first surface of the substrate, and making the solder pad on the substrate located in the through hole provided on the release film; providing a conductive adhesive film, attaching the conductive adhesive film on the exposed solder pad, wherein the conductive adhesive film covers the solder pad and the release film; cutting the conductive adhesive film so that the conductive adhesive film is divided into a first sub-portion and a second sub-portion, wherein the orthographic projection of the first sub-portion on the substrate is covered by the orthographic projection of the through hole on the substrate, and the orthographic projection of the first sub-portion on the substrate at least partially overlaps with the solder pad; removing the second sub-portion; arranging a light-emitting element on the side of the conductive adhesive film away from the solder pad, and the light-emitting element is electrically connected to the solder pad through the first sub-portion of the conductive adhesive film.

[0017] Preferably, the step of removing the second sub-portion includes: removing the second sub-portion and the release film simultaneously; or, after removing the second sub-portion, further includes: removing the release film.

[0018] Preferably, the release film comprises a first protective layer, a first release layer and a first adhesive layer which are stacked; before attaching the conductive adhesive film on the exposed pad, the method further comprises: removing the first protective layer.

[0019] Preferably, the conductive adhesive film comprises a second release layer and a second adhesive layer which are stacked; the step of attaching the conductive adhesive film to the exposed pad comprises: removing the second release layer; and attaching the second adhesive layer to the exposed pad.

[0020] Preferably, the first release layer and the second release layer are made of the same material.

[0021] The beneficial effects of the present application are as follows: Different from the prior art, the display back panel provided by the present application is provided with a release film, and the release film is provided with a through hole corresponding to the pad on the substrate. Since the pad protrudes from the first surface of the substrate, when the release film is attached to the substrate, the through hole is used to make way for the pad, so that the pad is located in the through hole, and the release film located around the pad is attached to the substrate. The release film facilitates the peeling of the conductive adhesive film therefrom, so that only part of the conductive adhesive film remains on the pad, reducing the amount of conductive adhesive film used and reducing costs. In addition, the preparation method of the display panel provided by the present application divides the attached conductive adhesive film into a first sub-portion corresponding to the pad and a second sub-portion corresponding to the release film. Since at least part of the second sub-portion is attached to the release film, it is convenient to separate the second sub-portion from the display back panel, so that the second sub-portion can be used for the next batch transfer, thereby improving the utilization rate of the conductive adhesive film and reducing the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a top view of an embodiment of a display backplane in the related art;

[0023] Figure 2 is a side view of an embodiment of a display backplane in the related art;

[0024] Figure 3 It is a structural schematic diagram of an embodiment of a display backplane of the present application;

[0025] Figure 4 is a top view of an embodiment of a release film of the present application;

[0026] Figure 5 It is a structural schematic diagram of another embodiment of the release film of the present application;

[0027] Figure 6 is a schematic structural diagram of an embodiment of a display panel of the present application;

[0028] Figure 7 It is a schematic diagram of a process of an embodiment of a method for manufacturing a display panel of the present application;

[0029] Figure 8 It is a structural schematic diagram of steps S130-S140 of the preparation method of the present application;

[0030] Fig. 9 It is a structural schematic diagram of step S150 of the preparation method of the present application;

[0031] Fig.10 It is a top view of an embodiment of the conductive adhesive film of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and effect of the present application clearer and more specific, the present application is further described in detail with reference to the accompanying drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0033] like Figure 1 and Figure 2 As shown, Figure 1 FIG. 1 is a top view of an embodiment of a display backplane in the related art. Figure 2 It is a side view of an embodiment of a display backplane of the related art. The display backplane includes a substrate 21 and a pad 22, and a plurality of pads 22 are provided on the first surface 21a of the substrate 21. Taking the Micro-LED display backplane as an example, a plurality of pads 22 are usually arranged on the substrate 21 in units of pixels, and the pads 22 protrude from the first surface 21a, which are used to electrically connect the Micro-LEDs. In order to realize the normal display and light emission after the Micro-LEDs are transferred to the display backplane in batches, the P electrode and the N electrode of the Micro-LED need to be electrically connected to the corresponding pads 22 on the substrate 21, respectively, to realize the conduction of the electrical signal, thereby realizing light emission. To realize this process, it is usually necessary to attach a conductive adhesive film (such as an ACF film, anisotropic conductive adhesive film) to the display backplane, so that the conductive adhesive film is located between the pad 22 and the P electrode and N electrode of the Micro-LED, and the conductive particles of the conductive adhesive film are used to realize the conduction between the pad 22 and the Micro-LED electrode. However, the inventors have discovered through research that the spacing between the pads 22 corresponding to adjacent pixels of the display backplane, especially the large-size display backplane, is relatively large, much larger than the size of the Micro-LED. In the related art, the entire surface of the conductive film is attached to the display backplane, but in fact, the effective area for electrical signal connection is only the area where the Micro-LED is transferred, which results in a huge waste of conductive film materials.

[0034] In view of this, in order to solve the above problems, see Figure 3 , Figure 3 1 is a schematic diagram of the structure of an embodiment of a display backplane of the present application. The present application provides a display backplane 20. The display backplane 20 includes a substrate 21 and a release film 10, and a first surface 21a of the substrate 21 is provided with a solder pad 22; the release film 10 is attached to the first surface 21a of the substrate 21, and the solder pad 22 is located in the through hole 10a.

[0035] The display backplane 20 provided in the present application is provided with a release film 10 on the substrate 21. The surface of the release film 10 away from the substrate 21 has low viscosity, and other film layers (such as conductive adhesive films) have low adhesion to the surface and can be smoothly peeled off from the surface. The release film 10 can also play a role in protecting the spacing area (Space area) between the pads 22, and does not affect the subsequent transfer of the Micro-LED to the display backplane 20. In addition, the release film 10 also realizes the flattening treatment of the display backplane 20 after the transfer, which is beneficial to the subsequent packaging process.

[0036] See also Figure 4 , Figure 4 1 is a top view of an embodiment of a release film of the present application. The release film 10 is used to be attached to a display backplane of the related art. The release film 10 of the present application is attached to the first surface 21a of the substrate 21. Figure 3 As shown, the release film 10 includes a first release layer 11 and a first adhesive layer 12 which are stacked, and a through hole 10a on the release film 10 penetrates the first release layer 11 and the first adhesive layer 12, and the through hole 10a is arranged corresponding to the pad 22, so that when the release film 10 is attached to the substrate 21, the pad 22 is located in the through hole 10a. The material of the first release layer 11 may include PET, PE, etc. The surface of the first release layer 11 facing away from the first adhesive layer 12 has low viscosity, and other film layers (such as conductive adhesive film) have low adhesion to the surface and can be smoothly peeled off from the surface.

[0037] The release film 10 provided in the present application is provided with a through hole 10a corresponding to the pad 22 on the substrate 21. Since the pad 22 protrudes from the first surface 21a of the substrate 21, as shown in FIG. Figure 3 As shown, when the release film 10 is attached to the first surface 21a of the substrate 21, the through hole 10a is used to make way for the pad 22, so that the pad 22 is located in the through hole 10a, and the release film 10 located around the pad 22 is bonded to the first surface 21a of the substrate 21 through the first adhesive layer 12. The release film 10 provided in the present application is used to isolate the conductive adhesive film and the substrate 21. When the conductive adhesive film is subsequently attached to the display back panel, only the portion of the conductive adhesive film corresponding to the through hole 10a can be attached to the pad 22, and the remaining portion is attached to the release film 10. The adhesion between the conductive adhesive film and the release film 10 is much smaller than the adhesion between the conductive adhesive film and the pad 22, which facilitates the peeling of the conductive adhesive film and the release film 10. Only a portion of the conductive adhesive film remains on the pad, reducing the amount of the conductive adhesive film, and the portion of the conductive adhesive film peeled off from the release film 10 can be reused, thereby reducing the production cost.

[0038] Optionally, see Figure 5 , Figure 51 is a schematic diagram of the structure of another embodiment of the release film of the present application. In this embodiment, the release film 10 further includes a first protective layer 13, and the first protective layer 13 is located on the side of the first release layer 11 away from the first adhesive layer 12. The first protective layer 13 is used to protect the first release layer 11 from being easily damaged. The first protective layer 13 is removed before the subsequent transfer step, so that the pad 22 is exposed in the through hole 10a, so that the subsequent conductive adhesive film can be attached to the pad 22.

[0039] Optionally, the first protective layer 13 covers the through hole 10a, so that the first protective layer 13 connects the release film 10 as a whole, and when the release film 10 is subsequently attached to the substrate 21, the first protective layer 13 can simultaneously cover the pad 22, so that the pad 22 is located in a closed space before the Micro-LED is transferred, and dust and other debris are prevented from entering the gap between the pads 22. In other embodiments, the through hole 10a can penetrate the first adhesive layer 12, the first release layer 11 and the first protective layer 13 at the same time.

[0040] Optionally, the through hole 10a may correspond to one or more pads 22. Specifically, one pixel of the display panel generally includes three Micro-LEDs (for example, one red Micro-LED, one green Micro-LED, and one blue Micro-LED), and each Micro-LED is provided with a P electrode and an N electrode. Figure 1 As shown, the display backplane is provided with a group of six pads 22 (in the dotted box in the figure) corresponding to each pixel. Since the group of pads 22 corresponding to each pixel are arranged close to each other, preferably, in order to facilitate the attachment of the release film 10 to the substrate 21, one through hole 10a can correspond to the six pads 22 of one pixel, that is, the through hole 10a can accommodate a group of six pads 22. In other embodiments, one through hole 10a can correspond to one or other number of pads 22.

[0041] Optionally, when the release film 10 is provided with a plurality of through holes 10a, the plurality of through holes 10a may be Figure 4 The spacing arrangement shown, that is, the release film 10 can be connected as a whole, in other embodiments, the plurality of through holes 10a can be interconnected.

[0042] Optionally, the material of the first adhesive layer 12 includes a pressure-sensitive adhesive. By applying pressure to the release film 10, the pressure-sensitive adhesive generates greater viscosity after being compressed, so that the release film 10 is stably connected to the substrate 21. Since the pressure-sensitive adhesive only achieves bonding through intermolecular forces, it will not produce chemical reactions on structures such as the substrate 21. The bonding can also be invalidated by a peeling process, thereby removing the release film 10. Specifically, the thickness of the first adhesive layer 12 is 5-10μm; the thickness of the first release layer 11 is 20-50μm, and the total height of the release film 10 can be slightly higher or slightly lower than the height of the pad 22 or equal to it, as long as it does not affect the subsequent transfer of the Micro-LED. Specifically, the cross-section of the through hole 10a parallel to the first release layer 11 is circular or rectangular, which is convenient for the subsequent cutting of the conductive adhesive film according to the shape of the through hole 10a.

[0043] Optionally, the distance d from the edge of the through hole 10a to the edge of the pad 22 in the through hole 10a and adjacent to the edge of the through hole 10a is in the range of 10-20 μm. When there is only one pad 22 in the through hole 10a, the distance d is the distance from the outer wall of the pad 22 to the inner wall of the adjacent through hole 10a; when there are multiple pads 22 in the through hole 10a, the distance d can be the distance from the outer wall of the multiple pads 22 to the inner wall of the adjacent through hole 10a, that is, the distance from the edge of the area where the pad 22 is located to the edge of the through hole 10a, such as Figure 4 As shown, it is convenient to cut the conductive film along the edge of the through hole 10a later without wasting the conductive film.

[0044] The present application also provides a display panel, see Figure 6 , Figure 6 1 is a schematic diagram of the structure of an embodiment of a display panel of the present application. The display panel 100 includes a display backplane 20, a conductive film 30 and a light-emitting element 40, wherein the conductive film 30 is attached to the pad 22, wherein the orthographic projection of the through hole 10a on the substrate 21 covers the orthographic projection of the conductive film 30 on the substrate 21, and the orthographic projection of the conductive film 30 on the substrate 21 covers the orthographic projection of the pad 22 on the substrate 21. The light-emitting element 40 is arranged on the side of the conductive film 30 away from the pad 22, and the light-emitting element 40 is electrically connected to the pad 22 through the conductive film 30. When the light-emitting element 40 is a Micro-LED, the P electrode and the N electrode thereon are electrically connected to the two pads 22 respectively. In other embodiments, the orthographic projection of the conductive film 30 on the substrate 21 is at least partially overlapped with the orthographic projection of the pad 22 on the substrate 21. The display backplane 20 with the conductive film 30 can be used to directly transfer the Micro-LED, and the conductive particles in the conductive film 30 can conduct the Micro-LED and the pad 22. Since the conductive adhesive film 30 of the present application only covers the effective conductive connection area of ​​the display backplane 20, that is, the pad 22 area, the usage of the conductive adhesive film 30 is greatly reduced, thereby reducing the cost.

[0045] See also Figure 7 The present application also provides a method for preparing a display panel, comprising:

[0046] Step S110 : providing a substrate 21 and a release film 10 , wherein a first surface 21 a of the substrate 21 is provided with a solder pad 22 , and the release film 10 is provided with a through hole 10 a corresponding to the solder pad 22 .

[0047] Step S120: attaching the release film 10 to the first surface 21a of the substrate 21, and positioning the pad 22 on the substrate 21 in the through hole 10a provided on the release film 10, as shown in FIG. Figure 3 As shown. The release film 10 includes a first adhesive layer 12 and a first release layer 11 which are stacked, and the through hole 10a penetrates the first adhesive layer 12 and the first release layer 11. Specifically, the first adhesive layer 12 is a pressure-sensitive adhesive, and pressure can be applied to the release film 10 so that the release film 10 is fixedly connected to the substrate 21 through the first adhesive layer 12.

[0048] Step S130: Refer to Figure 8 , a conductive adhesive film 30 is attached to the exposed pad 22, wherein the conductive adhesive film 30 covers the pad 22 and the release film 10. Since the finished conductive adhesive film 30 is usually a whole layer, the whole layer of the conductive adhesive film 30 can be attached to the substrate 21 in this step to cover the pad 22 and the release film 10 at the same time. Optionally, the conductive adhesive film 30 may include a second adhesive layer 31 and a second protective layer (not shown) that are stacked. The conductive adhesive film 30 may be first attached to the pad 22, and the second adhesive layer 31 may be attached to the pad 22. The second protective layer is located on the side of the second adhesive layer 31 away from the pad 22, and is used to protect the second adhesive layer 31. The second protective layer is removed before transferring the light-emitting element 40 to expose the second adhesive layer 31.

[0049] Step S140: Continue to read Figure 8 , the conductive adhesive film 30 is cut (the dotted line in the figure is the cutting line) so that the conductive adhesive film 30 is divided into a first sub-portion 301 and a second sub-portion 302, wherein the orthographic projection of the first sub-portion 301 on the substrate 21 is covered by the orthographic projection of the through hole 10a on the substrate 21, and the orthographic projection of the first sub-portion 301 on the substrate 21 overlaps at least partially with the pad 22. A laser device can be used to cut along the dotted line: the laser device is provided with a mask, and the laser can accurately cut along the edge of the through hole 10a at a place larger than 10-20μm from the periphery of the pad during cutting. This step divides the conductive adhesive film 30 into a first sub-portion 301 attached to the position of the pad 22 and a second sub-portion 302 corresponding to the non-pad 22 area. The shape of the laser cutting is cut into a rectangle or a circle according to the cutting effect of the laser and the shape of the through hole 10a.

[0050] Step S150: Refer to Fig. 9 , remove the second sub-section 302. Since the second sub-section 302 and the first sub-section 301 are separated into two parts, and the second sub-section 302 is attached to the release film 10, the bonding force between the two is small, so the second sub-section 302 is easy to peel off from the release film 10, and the first sub-section 301 can remain on the pad 22.

[0051] Step S160: a light emitting element 40 is arranged on the side of the conductive film 30 away from the pad 22, and the light emitting element 40 is electrically connected to the pad 22 through the first sub-portion 301 of the conductive film 30. Figure 6 shown.

[0052] Optionally, step S140 includes: removing the second sub-portion 302 and the release film 10 simultaneously, and the removed second sub-portion 302 can remain attached to the release film 10, which can protect the remaining conductive adhesive film 30 on the one hand, and can quickly separate the conductive adhesive film 30 and the release film 10 when used next time on the other hand; or, after step S150, it also includes: removing the release film 10. In other embodiments, the release film 10 may not be removed and may be left on the substrate 21 to protect the area between the pads 22.

[0053] Optionally, the release film 10 further includes a first protective layer 13, which is located on the side of the first release layer 11 away from the first adhesive layer 12; before step S130, the process further includes: removing the first protective layer 13 to expose the first release layer 11, so as to facilitate subsequent attachment to the conductive adhesive film 30.

[0054] Optionally, the conductive adhesive film 30 includes a second release layer (not shown) and a second adhesive layer 31 which are stacked, and step S130 includes: removing the second release layer; attaching the second adhesive layer 31 to the exposed pad 22. Specifically, the first release layer 11 and the second release layer are made of the same material. The release layer material of the conductive adhesive film 30 itself is consistent with the attached release layer material, so that the second sub-portion 302 can be more conveniently peeled off from the first release layer 11.

[0055] The remaining second subsection 302 can continue to be used for one or more subsequent transfers. Fig.10 , Fig.10It is a schematic diagram of the structure of the second sub-section 302 remaining after the conductive adhesive film 30 is cut and used once. The solid line frame in the figure is the cutting line of the first cutting, and the dashed line frame and the dotted line frame are the cutting lines that can be cut again later. It can be seen from the figure that the remaining second sub-section 302 can continue to be used, and the second sub-section 302 can be translated along the X or Y direction for a distance and then attached to the next display back panel for continued use. It can be seen from the dashed line frame and the dotted line frame in the figure that, compared with the related art that a piece of conductive adhesive film 30 can only be used once, a piece of conductive adhesive film 30 of the present application can be used at least four times, and the actual number of times the conductive adhesive film 30 is used is related to the size and shape of the conductive adhesive film 30 and the first sub-section. The rectangular first sub-section has the highest utilization rate.

[0056] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A display backplane, It is characterized in that include: A substrate, wherein a first surface of the substrate is provided with a solder pad; A release film is attached to the first surface of the substrate, the release film is provided with a through hole, and the pad is located in the through hole.

2. The display back panel according to claim 1, It is characterized in that The release film comprises a first release layer and a first adhesive layer which are stacked, and the through hole penetrates the first release layer and the first adhesive layer; Preferably, the material of the first adhesive layer includes pressure-sensitive adhesive.

3. The display back panel according to claim 2, It is characterized in that The thickness of the first adhesive layer is 5-10 μm; and / or, The thickness of the first release layer is 20-50 μm.

4. The display back panel according to claim 2, It is characterized in that The release film further includes a first protective layer, and the first protective layer is located on a side of the first release layer away from the first adhesive layer; Preferably, the first protection layer covers the through hole.

5. The display back panel according to claim 2, It is characterized in that The cross section of the through hole parallel to the first release layer is circular or rectangular.

6. The display back panel according to claim 1, It is characterized in that The distance from the edge of the through hole to the edge of the pad inside the through hole and adjacent to the edge of the through hole is in the range of 10-20 μm.

7. A display panel, It is characterized in that include: The display backplane as claimed in any one of claims 1 to 6; A conductive adhesive film is attached to the pad, wherein the orthographic projection of the through hole on the substrate covers the orthographic projection of the conductive adhesive film on the substrate, and the orthographic projection of the conductive adhesive film on the substrate at least partially overlaps with the pad; The light emitting element is arranged on a side of the conductive adhesive film away from the pad, and the light emitting element is electrically connected to the pad through the conductive adhesive film.

8. A method for preparing a display panel, It is characterized in that include: Providing a substrate and a release film, wherein a solder pad is provided on a first surface of the substrate, and a through hole corresponding to the solder pad is provided on the release film; Attaching the release film to the first surface of the substrate, and positioning the pad on the substrate in the through hole; Providing a conductive adhesive film, and attaching the conductive adhesive film on the exposed pad, wherein the conductive adhesive film covers the pad and the release film; Cutting the conductive adhesive film so that the conductive adhesive film is divided into a first sub-portion and a second sub-portion, wherein the orthographic projection of the first sub-portion on the substrate is covered by the orthographic projection of the through hole on the substrate, and the orthographic projection of the first sub-portion on the substrate at least partially overlaps with the pad; removing the second sub-portion; A light emitting element is arranged on a side of the conductive adhesive film away from the pad, and the light emitting element is electrically connected to the pad through the first sub-portion of the conductive adhesive film.

9. The preparation method according to claim 8, It is characterized in that The step of removing the second sub-portion comprises: removing the second sub-portion and the release film simultaneously; Alternatively, after removing the second sub-portion, the method further includes: removing the release film; Preferably, the release film comprises a first protective layer, a first release layer and a first adhesive layer which are stacked; Before attaching the conductive adhesive film on the exposed pad, the method further includes: The first protective layer is removed.

10. The preparation method according to claim 8, It is characterized in that The conductive adhesive film comprises a second release layer and a second adhesive layer which are stacked; the step of attaching the conductive adhesive film to the exposed pad comprises: removing the second release layer; Attaching the second adhesive layer to the exposed pad; Preferably, the first release layer and the second release layer are made of the same material.

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