Functional backplane and light-emitting apparatus

Abstract

The present application relates to the technical field of display. Disclosed are a functional backplane and a light-emitting apparatus. In the functional backplane, a first flexible circuit board is fixedly provided on a second surface of a substrate by means of a first attachment structure. The first flexible circuit board has a first region of a single-layer conductive structure and a second region of a double-layer conductive structure. Compared with the single-layer conductive structure, the double-layer conductive structure has a higher proportion of conductive material in unit space, such that during a high-temperature process, the amount of expansion in the second region is more different from the amount of expansion of the first attachment structure than from the amount of expansion in the first region. In the present application, the thickness of a target portion of the first attachment structure located in the second region is small, so as to provide an expansion space for the expansion of an attachment material of the first attachment structure, and further reduce the total amount of expansion of the first attachment structure, thus avoiding a great difference between the amount of expansion of the first attachment structure and the amount of expansion in the second region, reducing the warping possibility of functional backplanes, and improving the yield of functional backplanes.

Description

Functional back panel and light-emitting device

[0001] This disclosure claims priority to Chinese patent application No. 202310993850.5 filed on August 8, 2023, entitled “Functional backplane and light-emitting device.” The entire contents of the above case are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of display technology, and in particular to a functional backplane and a light-emitting device. Background Art

[0003] Light-emitting devices are currently developing towards ultra-narrow borders or even borderless to increase the screen-to-body ratio.

[0004] In related art, to increase the screen-to-body ratio of a light-emitting device, the electrode traces on the light-emitting side of the functional backplane are typically routed to the other side of the functional backplane via side traces, and a first drive signal is provided to the electrode traces of the functional backplane via an external circuit structure provided on the other side. To achieve signal transmission between the side traces and the external circuit structure, a flexible circuit board is designed on the other side of the functional backplane. This flexible circuit board is connected to the side traces and the external circuit structure, and the external circuit structure is connected to the electrode traces via the side traces connected to the flexible circuit board. Furthermore, the flexible circuit board can be bonded to the substrate of the functional backplane via a bonding structure to achieve a fixed connection between the flexible circuit board and the substrate.

[0005] Summary of the Invention

[0006] The present application provides a functional backplane and a light-emitting device, and the technical solutions are as follows:

[0007] In one aspect, a functional backplane is provided, comprising:

[0008] substrate;

[0009] a plurality of electronic components located on the first surface of the substrate;

[0010] a first connecting trace, wherein one end of the first connecting trace is located on the first surface of the substrate and connected to the electronic component, and the other end of the first connecting trace is bent from the first surface of the substrate and located on the second surface of the substrate;

[0011] a first flexible circuit board and a first bonding structure, wherein the first flexible circuit board is located on a second surface of the substrate away from the plurality of electronic components, the first bonding structure is located between the substrate and the first flexible circuit board, the first flexible circuit board is fixedly disposed on the second surface of the substrate via the first bonding structure, the first flexible circuit board is connected to the other end of the first connecting trace, and the first flexible circuit board is further connected to a first external circuit structure, and the first flexible circuit board is configured to transmit a first driving signal provided by the first external circuit structure to the electronic components via the first connecting trace;

[0012] In which, the first flexible circuit board has a first area and a second area, the first flexible circuit board includes a first conductive structure located in the first area, and a second conductive structure and a third conductive structure located in the second area and stacked; the first bonding structure has a plurality of target portions in the shape of strips located at least in the second area, and the thickness of the target portion of the first bonding structure is less than the thickness of other portions of the first bonding structure except the target portion.

[0013] Optionally, the plurality of target portions include a plurality of first grooves extending along the first direction and spaced apart in the second direction;

[0014] The first direction is an arrangement direction of the first areas and the second areas, and the second direction is perpendicular to the arrangement direction of the first areas and the second areas.

[0015] Optionally, the plurality of target portions further include a plurality of second grooves extending along the second direction and spaced apart in the second direction;

[0016] At least some of the plurality of second grooves are in communication with the first groove.

[0017] Optionally, the plurality of second grooves are located in the middle of the second area in the first direction.

[0018] Optionally, a distance between two adjacent first grooves along the second direction, and a distance between two adjacent second grooves along the second direction are both greater than or equal to 10 mm;

[0019] The width of the first groove ranges from 1 mm to 5 mm, the length of the first groove is equal to the length of the second area along the first direction, the width of the second groove ranges from 0.5 mm to 2 mm, and the length of the second groove is less than the spacing between two adjacent second grooves along the second direction.

[0020] Optionally, the plurality of target portions further include a third groove extending along the second direction, and a length of the third groove in the second direction is equal to a length of the first fitting structure in the second direction;

[0021] The third groove is located at the boundary between the first area and the second area.

[0022] Optionally, the plurality of target portions include a plurality of fourth grooves extending along the first direction and spaced apart in the second direction, and a plurality of fifth grooves extending along the second direction and spaced apart in the first direction;

[0023] Wherein, the plurality of fourth grooves and the plurality of fifth grooves form a grid shape.

[0024] Optionally, the width of the fourth groove and the fifth groove are both in the range of 100 microns to 150 microns, and the spacing between two adjacent fourth grooves in the second direction and the spacing between two adjacent fifth grooves in the first direction are both greater than or equal to 300 microns.

[0025] Optionally, the plurality of fourth grooves and the plurality of fifth grooves are also located in the first area.

[0026] Optionally, the first bonding structure includes a bonding material, and other parts of the first bonding structure except the target part are the parts of the first bonding structure having the bonding material, and the target part of the first bonding structure is the part of the first bonding structure not having the bonding material.

[0027] In another aspect, a functional backplane is provided, comprising:

[0028] substrate;

[0029] a plurality of electronic components on the first surface of the substrate;

[0030] a first connecting trace, wherein one end of the first connecting trace is located on the first surface of the substrate and connected to the electronic component, and the other end of the first connecting trace is bent from the first surface of the substrate and located on the second surface of the substrate;

[0031] a first flexible circuit board and a first bonding structure, wherein the first flexible circuit board is located on a second surface of the substrate away from the plurality of electronic components, the first bonding structure is located between the substrate and the first flexible circuit board, the first flexible circuit board is fixedly disposed on the second surface of the substrate via the first bonding structure, the first flexible circuit board is connected to the other end of the first connecting trace, and the first flexible circuit board is further connected to a first external circuit structure, and the first flexible circuit board is configured to transmit a first driving signal provided by the first external circuit structure to the electronic components via the first connecting trace;

[0032] In which, the first flexible circuit board has a first area and a second area, the first flexible circuit board includes a first conductive structure located in the first area, and a second conductive structure and a third conductive structure located in the second area and stacked, the first conductive structure, the second conductive structure and the third conductive structure are made of the same material; the first bonding structure includes a first part located in the first area and a second part located in the second area, and the difference between the thermal expansion coefficient of the material of the second part and the thermal expansion coefficient of the material of the first conductive structure is less than 1 / 3 million / degree Celsius.

[0033] Optionally, materials of the first conductive structure, the second conductive structure and the third conductive structure are all copper;

[0034] The coefficient of thermal expansion of the material of the second portion is less than or equal to 20 parts per million per degree Celsius.

[0035] Optionally, the material of the second portion is different from the material of the first portion, and the thermal expansion coefficient of the material of the second portion is smaller than the thermal expansion coefficient of the material of the first portion.

[0036] Optionally, the functional backplane further includes:

[0037] a second connecting trace, one end of the second connecting trace being located on the first surface of the substrate and connected to the electronic component, and the other end of the second connecting trace being bent from the second surface of the substrate and located on the second surface of the substrate, the second surface being located opposite to the first surface;

[0038] a second flexible circuit board and a second bonding structure, wherein the second flexible circuit board is located on a second surface of the substrate away from the electronic component, and the second flexible circuit board and the first flexible circuit board are spaced apart in a first direction, the second bonding structure is located between the substrate and the second flexible circuit board, the second flexible circuit board is fixedly arranged on the second surface of the substrate via the second bonding structure, the second flexible circuit board is connected to the other end of the second connecting trace, and the second flexible circuit board is further connected to a second external circuit structure, and the second flexible circuit board is used to transmit a second driving signal provided by the second external circuit structure to the electronic component via the second connecting trace;

[0039] The second flexible circuit board includes a fourth conductive structure, and each region of the second bonding structure has the same thickness.

[0040] In another aspect, a light emitting device is provided, comprising: a power supply component and the functional backplane as described in the above aspect;

[0041] Wherein, the power supply component is used to supply power to the functional backplane. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0043] FIG1 is a cross-sectional view of a functional backplane provided by the related art;

[0044] FIG2 is a front plan view of a circuit board provided by the related art;

[0045] FIG3 is a back view of a circuit board provided in the related art;

[0046] FIG4 is a cross-sectional view of a functional backplane provided in an embodiment of the present application;

[0047] FIG5 is a top view of a first flexible circuit board provided in an embodiment of the present application;

[0048] FIG6 is a cross-sectional view taken along the MM direction in FIG5;

[0049] FIG7 is a schematic diagram of laminating a first flexible circuit board to a substrate using a first laminating structure according to an embodiment of the present application;

[0050] FIG8 is a schematic diagram of a substrate warping provided in an embodiment of the present application;

[0051] FIG9 is a schematic diagram of a first flexible circuit board and a first bonding structure provided in an embodiment of the present application;

[0052] FIG10 is a schematic diagram of another first flexible circuit board and a first bonding structure provided in an embodiment of the present application;

[0053] FIG11 is a schematic diagram of another first flexible circuit board and a first bonding structure provided in an embodiment of the present application;

[0054] FIG12 is a top view of a first surface of a functional backplane provided in an embodiment of the present application;

[0055] FIG13 is a top view of the second surface of a functional backplane provided in an embodiment of the present application;

[0056] FIG14 is a schematic diagram of another first flexible circuit board and a first bonding structure provided by an embodiment of the present application;

[0057] FIG15 is a partial schematic diagram of a first bonding structure provided in an embodiment of the present application;

[0058] FIG16 is a schematic diagram of a release film provided in an embodiment of the present application;

[0059] FIG17 is a schematic diagram of another release film provided in an embodiment of the present application;

[0060] FIG18 is a schematic diagram of another first flexible circuit board and a first bonding structure provided in an embodiment of the present application;

[0061] FIG19 is a partial three-dimensional schematic diagram of a release film provided in an embodiment of the present application;

[0062] FIG20 is a schematic diagram of a first conductive layer of a first flexible circuit board provided in an embodiment of the present application;

[0063] FIG21 is a schematic diagram of a second conductive layer of a first flexible circuit board provided in an embodiment of the present application;

[0064] FIG22 is a cross-sectional view of a first flexible circuit board provided in an embodiment of the present application;

[0065] FIG23 is a partial schematic diagram of a first conductive layer of a first flexible circuit board provided in an embodiment of the present application;

[0066] FIG24 is a partial schematic diagram of a first conductive layer of another first flexible circuit board provided in an embodiment of the present application;

[0067] FIG25 is a partial schematic diagram of FIG21;

[0068] FIG26 is a schematic diagram of a second flexible circuit board provided in an embodiment of the present application;

[0069] Figure 27 is a schematic diagram of another first flexible circuit board and first bonding structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0070] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0071] Some embodiments of the present disclosure provide a light-emitting device, which includes a functional backplane and may of course also include other components, for example, it may include a circuit for providing an electrical signal to the functional backplane to drive the functional backplane to emit light. This circuit can be called a control circuit and may include a circuit board and / or an integrated circuit (IC) electrically connected to the functional backplane.

[0072] Optionally, the lighting device may further include a power supply component, which may be used to supply power to the functional backplane.

[0073] In some embodiments, the light emitting device may be a lighting device, in which case the light emitting device is used as a light source to achieve a lighting function. For example, the light emitting device may be a backlight module in a liquid crystal display device, a lamp for internal or external lighting, or various signal lights.

[0074] In other embodiments, the light-emitting device may be a display device, in which case the functional backplane is a display substrate for realizing the function of displaying an image (i.e., a picture). The light-emitting device may include a display or a product including a display. The display may be a flat panel display (FPD), a microdisplay, and the like. If divided according to whether the user can see the back of the display, the display may be a transparent display or an opaque display. If divided according to whether the display can be bent or curled, the display may be a flexible display or an ordinary display (which may be called a rigid display). For example, products including displays may include: computer monitors, televisions, billboards, laser printers with display functions, telephones, mobile phones, personal digital assistants (PDAs), laptop computers, digital cameras, camcorders, viewfinders, vehicles, large-area walls, theater screens, or stadium signs.

[0075] Some embodiments of the present disclosure provide a functional backplane, as shown in Figures 1 and 2, the functional backplane 100 includes: a circuit board 101, and at least one electronic component 102 arranged on the circuit board 101. The electronic component 102 may include a micro light emitting diode, a micro integrated circuit chip, a micro sensor, a micro driver, etc., which are not limited here.

[0076] In some embodiments, taking the electronic component 102 as a micro-light emitting diode as an example, the functional backplane 100 can be used as a backlight source or a display device. In the case where the functional backplane 100 is used as a backlight source, a passive display panel can be used to display a full-color picture, such as a liquid crystal display panel (LCD). At this time, the functional backplane 100 as a whole can emit monochromatic light or polychromatic light (such as white light). By arranging multiple micro-light emitting diodes in a matrix and combining regional dimming technology, more refined brightness control and higher color contrast can be achieved. In the case where the functional backplane 100 is used as a display device, micro-light emitting diodes capable of emitting light of different colors can be provided on the functional backplane 100, which cooperate with each other to display a full-color picture with higher brightness and contrast.

[0077] At present, considering the process yield and manufacturing cost, when preparing large-size products, multiple functional back panels 100 can be spliced ​​together. In order to avoid the sense of separation between adjacent functional back panels due to splicing, which affects the user experience, the functional back panel is designed to have an ultra-narrow frame or even no frame to present a seamless splicing effect. This is the development direction in the field.

[0078] Micro-LED display technology is widely recognized as a very promising third-generation display technology, making it easier to implement small-size splicing technology to assemble infinitely larger displays. Micro-LED displays can be Micro LED (Micro Light Emitting Diode) or Mini LED (Mini Light Emitting Diode).

[0079] In order to achieve an ultra-narrow bezel display, as shown in Figures 1 to 3, in the related art, two opposite surfaces of the substrate S of the circuit board 10 are provided with traces, specifically: the first surface of the substrate S is provided with a trace F1 for connecting to the electronic component 102, and the lead-out portion D of the trace F1 is led to the second surface of the substrate S through the side trace C, and electrically connected to the trace F2 (such as at least one fan-out trace) provided on the second surface of the substrate S of the circuit board 101, such as making the binding area B on the second surface of the substrate S of the circuit board 10, thereby achieving a narrow bezel design. However, since both surfaces of the substrate S are provided with traces, it is easy to cause scratches on one of the surface circuits during the production process, which is not conducive to ensuring product yield and makes the production cost higher.

[0080] In the first solution, referring to FIG. 4 , the functional backplane 200 may include a substrate 201 , a plurality of electronic components 202 located on a first surface 201 a of the substrate 201 , a first connecting trace 203 , a first flexible circuit board 204 and a first bonding structure 205 .

[0081] The substrate 201 may be a glass substrate 201. Each of the electronic components 202 may include a pixel unit, and the pixel units included in the multiple electronic components 202 may have different colors. For example, the multiple electronic components 202 may include a red (R) pixel unit, a green (G) pixel unit, and a blue (B) pixel unit.

[0082] One end of the first connecting trace 203 is located on the first surface 201a of the substrate 201 and is connected to the electronic component 202. The other end of the first connecting trace 203 bends from the first side surface 201c of the substrate 201 and is located on the second surface 201b of the substrate 201. In other words, a portion of the first connecting trace 203 is located on the first surface 201a of the substrate 201, a portion is located on the first side surface 201c of the substrate 201, and a portion is located on the second surface 201b of the substrate 201.

[0083] The first flexible circuit board 204 is located on the second surface 201b of the substrate 201, away from the plurality of electronic components 202 (the first surface 201a and the second surface 201b of the substrate 201 are oppositely disposed). A first bonding structure 205 is located between the substrate 201 and the first flexible circuit board 204, and the first flexible circuit board 204 is fixed to the second surface 201b of the substrate 201 via the first bonding structure 205. The first flexible circuit board 204 is connected to the other end of the first connecting trace 203 and is also connected to the first external circuit structure 300. The first flexible circuit board 204 is used to transmit the first drive signal provided by the first external circuit structure 300 to the electronic components 202 via the first connecting trace 203.

[0084] That is, in the embodiment of the present application, by providing the first flexible circuit board 204 on the second surface 201b of the substrate 201 and connecting to the external circuit structure through the lines in the first flexible circuit board 204, it is possible to prepare wiring only on the first surface 201a of the substrate 201, thereby avoiding the problem that the surface on which the wiring is prepared is easily scratched during the process of preparing the wiring surface later, when the wiring is prepared separately on the first surface 201a and the first surface 201b of the substrate 201, thereby ensuring the product yield.

[0085] Furthermore, in the embodiment of the present application, the first conductive structure 2041 of the first flexible circuit board 204 may include multiple first signal lines, some of which are connected to the second conductive structure 2042, and some of which are connected to the third conductive structure 2043. An insulating layer a3 is provided between the second conductive structure 2042 and the third conductive structure 2043 to insulate the second conductive structure 2042 from the third conductive structure 2043.

[0086] One end of the first signal line can be connected to the other end of the first connection trace 203, and the other end of the first signal line can be connected to the second conductive structure 2042 or the third conductive structure 2043. In addition, the length occupied by the second conductive structure 2042 and the third conductive structure 2043 in the second direction Y is less than the length occupied by the multiple first signal lines in the second direction Y.

[0087] Figure 5 is a top view of the first flexible circuit board provided in an embodiment of the present application. Figure 6 is a cross-sectional view of Figure 5 along the MM direction. Referring to Figures 5 and 6, it can be seen that the first flexible circuit board 204 has a first region 204a and a second region 204b. The first flexible circuit board 204 includes a first conductive structure 2041 located in the first region 204a, and a second conductive structure 2042 and a third conductive structure 2043 located in the second region 204b and stacked. In other words, the first region 204a is a single-layer conductive structure, and the second region 204b is a double-layer conductive structure. Figure 6 only illustrates the positional relationship between the first conductive structure 2041, the second conductive structure 2042, and the third conductive structure 2043, and does not represent the actual appearance of each conductive structure.

[0088] Typically, during the manufacturing process of a functional backplane, as shown in Figure 7 , after the first flexible printed circuit board 204 is bonded using the first bonding structure 205, it undergoes multiple high-temperature treatments at 150°C (degrees Celsius) and a single high-temperature treatment at 270°C. However, as shown in Figure 8 , after the high-temperature treatment, the functional backplane 200 exhibits warpage in a target region of the substrate 201 (the target region being the projection of the second region 204b of the first flexible printed circuit board 204 onto the substrate 201) of 170 to 200 μm.

[0089] Optionally, after the first flexible circuit board 204 is bonded using the first bonding structure 205, it can undergo three high-temperature treatments at 150°C and one at 270°C. After the first bonding structure 205 bonds the first flexible circuit board 204, the first bonding structure 205 needs to be cured at a temperature of 150°C; after the first connecting trace 203 is formed, the material forming the first connecting trace 203 needs to be cured at a temperature of 150°C; after the protective layer for protecting the first connecting trace 203 is formed, the protective layer needs to be cured at a temperature of 150°C; and the fixed connection between the light-emitting diode LED and the substrate needs to be achieved through a die-bonding process at a temperature of 270°C.

[0090] The first flexible circuit board 204 primarily includes a polyimide (PI) layer, a polyethylene terephthalate (PET) layer, and a conductive structure, wherein the conductive structure is typically made of copper foil. In some embodiments, the overall coefficient of thermal expansion (CTE) of the first flexible circuit board 204 is between 18 ppm / °C and 22 ppm / °C. PPM stands for parts per million, and ppm / °C can be used to indicate volumetric expansion or contraction, such as the percentage of volume expansion per 1°C increase in temperature. For example, 18 ppm / °C indicates an 18-parts-per-million expansion per 1°C increase in temperature.

[0091] The CTE of PI material is 20ppm / °C to 30ppm / °C, the CTE of PET material is 60ppm / °C to 80ppm / °C, and the CTE of copper foil is 17.8ppm / °C. Typically, the CTE of the laminating material of the first laminating structure 205 is 42ppm / °C to 134ppm / °C. During high-temperature processes, the higher the temperature, the greater the expansion of the laminating material. If the expansion difference between the laminating material and the first flexible circuit board 204 is too large, the substrate 201 may warp.

[0092] The structure of the first flexible circuit board 204 described above shows that the first flexible circuit board 204 has a first region 204a with a single-layer conductive structure and a second region 204b with a double-layer conductive structure. When the same laminating material is used and the laminating material thickness and planar area per unit space are the same, the higher the copper content per unit space (e.g., the higher the copper content per unit area or per unit volume), the greater the difference in expansion between the laminating material and the region during high-temperature processing, resulting in more severe warping of the substrate 201.

[0093] Specifically, the force exerted by copper expansion can cause the first flexible circuit board 204 to pull and deform (e.g., increase its size along the expansion direction), while the force exerted by the bonding material expansion can cause the first bonding structure 205 to pull and deform. However, at the same temperature, the magnitude of the force exerted by copper expansion and the magnitude of the force exerted by the bonding material expansion differ. For a given unit space, at a given temperature, the magnitude of the force exerted by copper expansion is positively correlated with the percentage of copper content of the first flexible circuit board 204 in that space. That is, if the percentage of copper content of the first flexible circuit board 204 in that space is high, the greater the force required for copper expansion per unit size, the smaller the thermal expansion coefficient, and thus the smaller the tensile deformation. If the percentage of copper content of the first flexible circuit board 204 in that space is low, the smaller the force required for copper expansion per unit size, the greater the thermal expansion coefficient, and thus the larger the tensile deformation.

[0094] In the embodiment of the present application, the thermal expansion coefficient of the laminating material is slightly different from that of the first region 204a of the single-layer conductive structure, but significantly different from that of the second region 204b of the double-layer conductive structure. Therefore, if the thermal expansion coefficient of the laminating material remains constant within any unit space (i.e., the magnitude of the force exerted by the laminating material during expansion remains constant), the tensile deformation of the second region 204b of the first flexible printed circuit board 204 will differ significantly from that of the first laminating structure 205, while the tensile deformation of the first region 204a of the first flexible printed circuit board 204 will differ slightly from that of the first laminating structure 205. Furthermore, the second region 204b of the double-layer conductive structure is more susceptible to warping than the first region 204a of the single-layer conductive structure, which in turn causes the portion of the functional backplane located in the second region 204b to be more susceptible to warping.

[0095] It should be noted that the amount of expansion of an object is positively correlated with the thermal expansion coefficient of the object's material. That is, at the same temperature, the greater the thermal expansion coefficient of the object's material, the greater its deformation; the smaller the thermal expansion coefficient of the object's material, the smaller its deformation.

[0096] Since the thermal expansion coefficient of the first flexible circuit board 204 is smaller than that of the bonding material of the first bonding structure 205, in order to reduce the possibility of warping of the functional backplane, the thermal expansion coefficients of the two can be made as close as possible or the expansion amount of the first bonding structure 205 can be reduced.

[0097] In an embodiment of the present application, Figure 9 is a top view of a first bonding structure and a first flexible circuit board provided in an embodiment of the present application. Referring to Figure 9, the first bonding structure 205 has a plurality of strip-shaped target portions 205a located at least in the second region 204b. The target portions 205a of the first bonding structure 205 are thinner than the thickness of the remaining portions of the first bonding structure 205 excluding the target portions 205a.

[0098] During the subsequent high-temperature process of forming the functional backplane, since the thickness of the target portion 205a is relatively small, expansion space can be provided for the expansion of the bonding material of the first bonding structure 205. The expansion space can accommodate a portion of the expansion of the first bonding structure 205, thereby reducing the total expansion of the first bonding structure 205, avoiding the first bonding structure 205 from expanding too much and causing a large difference in expansion with the second area 204b of the first flexible circuit board 204, thereby avoiding the possibility of warping of the functional backplane and improving the yield of the functional backplane.

[0099] In summary, an embodiment of the present application provides a functional backplane, in which a first flexible circuit board is fixedly arranged on the second surface of a substrate by a first bonding structure. The first flexible circuit board has a first region with a single-layer conductive structure and a second region with a double-layer conductive structure. Since the double-layer conductive structure has a higher proportion of conductive material per unit space than the single-layer conductive structure, the expansion amount of the second region of the double-layer conductive structure during high temperature is greater than the expansion amount of the first region of the single-layer conductive structure, and the difference from the expansion amount of the first bonding structure is greater. The present application designs the thickness of the target portion located in the second region of the first bonding structure to be smaller, which can provide expansion space for the expansion of the bonding material of the first bonding structure, thereby reducing the total expansion amount of the first bonding structure. This can avoid the expansion amount of the first bonding structure being too large, resulting in a large difference in expansion amount with the second region of the first flexible circuit board, thereby avoiding the possibility of warping of the functional backplane and improving the yield of the functional backplane.

[0100] 9 , the plurality of target portions 205 a include a plurality of first grooves C1 extending along a first direction X and spaced apart along a second direction Y. The first direction X is the arrangement direction of the first regions 204 a and the second regions 204 b , and the second direction Y is perpendicular to the arrangement directions of the first and second directions X and Y.

[0101] Generally, the functional back panel 10 is more likely to warp in the second direction Y. Therefore, by designing a plurality of first grooves C1 extending along the first direction X and arranged along the second direction Y, a large amount of expansion space can be provided for the first bonding structure 205 to expand in the second direction Y, thereby reducing the total expansion of the first bonding structure 205 in the second direction Y. This can reduce the possibility of the functional back panel warping in the second direction Y.

[0102] As an optional implementation, Figure 10 is a top view of another first bonding structure and first flexible circuit board provided in an embodiment of the present application. Referring to Figure 10 , the plurality of target portions 205a further include a plurality of second grooves C2 extending along the second direction Y and spaced apart in the second direction Y. At least some of the plurality of second grooves C2 communicate with the first groove C1.

[0103] By providing a plurality of second grooves C2, expansion space can be further provided for the expansion of the first bonding structure 205, thereby reducing the total expansion amount of the first bonding structure 205. This can further reduce the possibility of warping of the functional backplane 10.

[0104] Optionally, the plurality of second grooves C2 may be located in the middle of the second region 204b in the first direction X to avoid affecting the bonding effect of the portion of the first bonding structure 205 located at the plurality of second grooves C2 away from the first region 204a due to its shorter length in the first direction X.

[0105] As another optional implementation, Figure 11 is a top view of another first bonding structure and first flexible circuit board provided in an embodiment of the present application. Referring to Figure 11 , the plurality of target portions 205a further include a third groove C3 extending along the second direction Y. The length of the third groove C3 in the second direction Y is equal to the length of the first bonding structure 205 in the second direction Y. The third groove C3 is located at the boundary between the first region 204a and the second region 204b.

[0106] The third groove C3 can further provide expansion space for the first bonding structure 205, thereby reducing the total expansion amount of the first bonding structure 205. This can further reduce the possibility of warping of the functional backplane.

[0107] Optionally, since the third groove C3 is located at the boundary between the first region 204a and the second region 204b, the portion of the first bonding structure 205 where the multiple second grooves C2 are located away from the first region 204a can have a larger length in the first direction X (equal to the length of the second region 204b in the first direction X), thereby ensuring the bonding effect of the first bonding structure 205.

[0108] In the embodiment of the present application, referring to Figures 12 and 13 , the functional backplane 10 further includes a plurality of first connection pads 206 located on the first surface 201a of the substrate 201, and a plurality of second connection pads 207 located on the second surface 201b of the substrate 201 and corresponding one-to-one with the plurality of first connection pads 206. Furthermore, the functional backplane 10 further includes a plurality of first connection traces 203 corresponding to the plurality of first connection pads 206 and the plurality of second connection pads 207. One end of each first connection trace 203 is connected to the electronic component 202 via a corresponding first connection pad 206, and the other end is connected to the first flexible circuit board 204 via a corresponding second connection pad 207.

[0109] Optionally, the plurality of first connection pads 206 are spaced apart in the second direction Y, and the plurality of second connection pads 207 are spaced apart in the second direction Y, thereby avoiding short circuits between different electrodes.

[0110] To ensure that each second connection pad 207 can be connected to the first flexible circuit board 204, the length of the first flexible circuit board 204 in the second direction Y needs to be greater than or equal to the length occupied by the plurality of second connection pads 207 in the second direction Y. Of course, the length of the first flexible circuit board 204 in the second direction Y needs to be less than the length of the substrate 201 in the second direction Y.

[0111] 5 , the minimum value Amin of the length A of the first flexible circuit board 204 in the second direction Y is equal to the length occupied by the plurality of second connection pads 207 in the second direction Y. The maximum value Amax of A is equal to the length of the substrate 201 in the second direction Y minus 30 μm (micrometers).

[0112] In addition, since the first signal line in the first flexible circuit board 204 needs to be designed for line retraction, the length B of the first flexible circuit board 204 in the first direction X may be in a range of 20 μm to 50 μm.

[0113] In the embodiment of the present application, based on the signal transmission resistance and reliability design requirements of the first flexible circuit board 204, the length C of the first region 204a in the first direction X must be greater than or equal to 1 / 3 of the length B of the first flexible circuit board 204 in the first direction X, and less than or equal to the length B of the first flexible circuit board 204 in the first direction X minus 10 mm. That is, the minimum length C of the first region 204a in the first direction X is Cmin = (1 / 3 × B) mm, and the maximum length Cmax = (B - 10) mm.

[0114] Accordingly, the length D of the second region 204b in the first direction X must be greater than or equal to 10 mm and less than or equal to 2 / 3 of the length B of the first flexible circuit board 204 in the first direction X. That is, the minimum length D of the second region 204b in the first direction X is Dmin = 10 mm, and the maximum length Dmax is Dmax = (2 / 3 × B) mm. The reason why the length D of the second region 204b in the first direction X must be greater than or equal to 10 mm is that if the length D is less than 10 mm, the signal transmission resistance will be too high, resulting in excessively high temperatures. Excessively high temperatures can negatively impact reliability, leading to lower reliability.

[0115] In this embodiment of the present application, while ensuring that signal transmission by the first flexible printed circuit board 204 is not affected, the length D of the second region 204b of the double-layer conductive structure in the first direction X is minimized. This reduces the design complexity of the double-layer conductive structure, thereby reducing the area of ​​the warping region and minimizing the likelihood of warping. Specifically, the length D of the second region 204b in the first direction X can be set to a minimum of 10 mm, while the length D of the first region 204a in the first direction X can be set to a maximum of (B-10) mm.

[0116] Optionally, to ensure that the first bonding structure 205 effectively bonds the substrate 201 and the first flexible circuit board 204, the spacing E between two adjacent first grooves C1 along the second direction Y cannot be too small. Otherwise, the portion of the first bonding structure 205 located between the two first grooves C1 will be isolated from the rest of the structure, thereby affecting the bonding effect. For example, referring to FIG. 9 , the spacing E between two adjacent first grooves C1 along the second direction Y can be greater than or equal to 10 mm.

[0117] In addition, the first grooves C1 are evenly arranged within the length range of the first fitting structure 205 in the second direction Y. For example, the distance between any two adjacent first grooves C1 along the second direction Y is the same.

[0118] Optionally, referring to Figure 9, the length F of the first groove C1 in the second direction Y (i.e., the width of the first groove C1) can be designed based on the expansion of the bonding adhesive and the required size for stress release. For example, the expansion of the bonding material of the first bonding structure 205 at high temperature can be calculated based on its thermal expansion coefficient. When the high temperature reaches up to 270°C, the expansion of the first bonding structure 205 can reach 0.7mm, and considering that a certain amount of space is required for stress release, the minimum value Fmin of the width F of the first groove C1 needs to be greater than 0.7mm, for example, it can be 1mm. As for the maximum value Fmax of the width F of the first groove C1, considering that the width of the first groove C1 is too wide, it will affect the bonding effect and cause the surface to be uneven after bonding. Therefore, the maximum value Fmax of the width F of the first groove C1 is set to 5mm. That is, the range of the width F of the first groove C1 satisfies: 1mm≤F≤5mm.

[0119] Optionally, referring to FIG. 10, the length G of the second groove C2 in the first direction X (i.e., the width of the second groove C2) and the length of the third groove C3 in the first direction X (i.e., the width of the third groove C3) G can also be designed according to the expansion amount of the bonding adhesive and the dimensions required for stress release. Since the width of the groove extending in the second direction Y needs to consider not only expansion but also the bonding effect of the part of the groove away from the first region 204a, the minimum value Gmin of the width of the groove extending in the second direction Y can be designed to be less than 0.7 mm, for example, 0.5 mm. Although a width of 0.5 mm may be difficult to allow for the expansion amount of the bonding adhesive, the functional backplane is not easily warped in the second direction Y, and the width of 0.5 mm also has a certain expansion space, so the impact on accommodating expansion is not significant. As for the maximum value Gmax of the width G, considering that an overly wide groove width will affect the bonding effect and cause the surface to be uneven after bonding, the maximum value Gmax of the width G of the groove is set to 2 mm. That is, the range of the width G of the second groove C2 and the width G of the third groove C3 satisfies: 1 mm ≤ G ≤ 2 mm.

[0120] For the design of the length H of the second groove C2 in the second direction Y (the length of the second groove C2), since the length of the second region 204b in the first direction X is compressed to 10 mm, in order to prevent the length I of the part of the first bonding structure 205 located away from the first region 204a in the second groove C2 in the first direction X from being too small, resulting in too small a bottom bonding area and thus a deteriorated bonding effect, it is necessary to design the length H of the second groove C2 to be less than the spacing E between two adjacent first grooves C1 in the second direction Y, that is, to satisfy H < E. Through this design, it can be ensured that the first bonding structure 205 has connected parts on both sides of the second groove C2, and it will not cause the part of the first bonding structure 205 located away from the first region 204a in the second groove C2 to be an island bonding.

[0121] Optionally, referring to FIG. 10, the range of the distance I between the boundary of the second groove C2 away from the first region 204a and the boundary of the first bonding structure 205 away from the first region 204a can be 4 mm ≤ I ≤ 4.75 mm. The maximum value Imax of I = 4.75 mm is calculated based on the condition that the midline of the second groove C2 and the midline of the second region 204b are collinear, the width D of the second region 204b in the first direction X = 10 mm, and the width G of the second groove C2 = 0.5 mm (the calculation method is 10 / 2 - 0.5 / 2 = 4.75 mm).

[0122] Furthermore, referring to Figure 10 , the spacing J between two adjacent second grooves C2 in the second direction Y is greater than or equal to 10 mm, thereby ensuring the continuity of the first bonding structure 205 and ensuring a good bonding effect. The second grooves C2 are evenly spaced within the length of the first bonding structure 205 in the second direction Y. For example, the distance between any two adjacent second grooves C2 in the second direction Y is the same.

[0123] Furthermore, to ensure the bonding effect of the first bonding structure 205, the length of the first bonding structure 205 along the first direction X is equal to the length of the first flexible circuit board 204 along the first direction X. That is, referring to FIG. 11 , the length K of the third groove C3 in the second direction Y can be equal to the length A of the first flexible circuit board 204 in the second direction Y, i.e., K=A.

[0124] In the embodiment of the present application, as shown in FIG9 , the design of the first groove C1 extending in the first direction X can increase the expansion of the bonding material of the first bonding structure 205 under a high-temperature process, effectively solving the problem of a large difference in the thermal expansion coefficient of the first flexible circuit board 204 and the thermal expansion coefficient of the bonding material of the first bonding structure 205, which causes the first flexible circuit board 204 to pull the substrate 201 and cause the functional backplane to warp in the second direction Y.

[0125] Compared to Figure 9, the design in Figure 10 adds a second groove C2 extending along the second direction Y. This increases the expansion of the bonding material of the first bonding structure 205 along the length (first direction X) of the first flexible circuit board 204 while also increasing the expansion of the first flexible circuit board 204 along the width (second direction Y). The design in Figure 11 places the groove extending along the second direction Y at the junction of the first region 204a and the second region 204b. Its length K is the same as the length A of the first flexible circuit board 204. This third groove C3 extends through the entire first bonding structure 205. This isolates the bonding material in the first region 204a from the bonding material in the second region 204b, preventing the cascading effects of expansion and contraction and stress release between the two regions at high temperatures. In Figures 9 and 10, to illustrate the positional relationship between the first flexible circuit board 204 and the first bonding structure 205, the first bonding structure 205 is depicted on the first flexible circuit board 204.

[0126] As another alternative implementation, referring to Figures 14 and 15 , the plurality of target portions 205a include a plurality of fourth grooves C4 extending along the first direction X and spaced apart in the second direction Y, and a plurality of fifth grooves C5 extending along the second direction Y and spaced apart in the first direction X. The plurality of fourth grooves C4 and the plurality of fifth grooves C5 form a grid. In Figure 14 , lines are used to illustrate the fourth grooves C4 and the fifth grooves C5.

[0127] During the preparation of the first bonding structure 205, an uncured bonding material is first formed. A grid-like release film is then attached to one side of the bonding material. Finally, the release film is pressed by pressure to form the grid-like first bonding structure 205. The fourth groove C4 and the fifth groove C5 in the first bonding structure 205 are both formed by pressing the release film. The intersecting grooves provide space for expansion of the first bonding structure 205.

[0128] In an embodiment of the present application, referring to FIG16 , the portion of the release film located in the first region 204a can be a smooth surface, while the portion located in the second region 204b can be a textured surface. Furthermore, the first region 204a of the first bonding structure 205 can be a flat bonding portion, while the second region 204b can be formed into a plurality of fourth grooves C4 and a plurality of fifth grooves C5, providing expansion space for high-temperature expansion. Alternatively, referring to FIG17 , the portion of the release film located in the first region 204a can also be a textured film, that is, referring to FIG18 , the plurality of fourth grooves C4 and the plurality of fifth grooves C5 can also be located in the first region 204a. This approach not only provides expansion space for the expansion of the bonding material in the second region 204b, but also provides expansion space for the expansion of the bonding material in the first region 204a.

[0129] Alternatively, referring to FIG19 , the release film may have a plurality of first protrusions in a strip shape and a plurality of second protrusions in a strip shape. The plurality of first protrusions and the plurality of second protrusions are arranged vertically. The plurality of first protrusions may be used to form a plurality of fourth grooves C4, and the plurality of second protrusions may be used to form a plurality of fifth grooves C5.

[0130] The width of the first protrusion affects the width of the fourth groove C4, the width of the second protrusion affects the width of the fifth groove C5. Furthermore, the spacing between adjacent first protrusions affects the spacing between adjacent fourth grooves C4, and the spacing between adjacent second protrusions affects the spacing between adjacent fifth grooves C5.

[0131] For example, the width P of the first protrusion and the second protrusion ranges from 100 μm to 150 μm, and the width of the fourth groove C4 and the fifth groove C5 ranges from 100 μm to 150 μm. The spacing Q between adjacent first protrusions and the spacing Q between adjacent second protrusions are both greater than or equal to 100 μm, and the spacing between two fourth grooves C4 in the second direction Y and the spacing between two adjacent fifth grooves C5 in the first direction X are both greater than or equal to 300 μm.

[0132] Furthermore, in order to form the fourth groove C4 and the fifth groove C5 by the first protrusion and the second protrusion through the release film pressing, the height T of the first protrusion and the second protrusion can be greater than or equal to 1 / 2 of the thickness of the first bonding structure 205, and less than or equal to the thickness of the first bonding structure 205. For example, assuming that the thickness of the first bonding structure 205 is 20 μm, the height N of the first protrusion and the second protrusion satisfies: 10 μm ≤ N ≤ 20 μm.

[0133] In the embodiment of the present application, the first bonding structure 205 includes a bonding material. The portions of the first bonding structure 205 other than the target portion 205a are the portions of the first bonding structure 205 that include the bonding material. The target portion 205a of the first bonding structure 205 is the portion of the first bonding structure 205 that does not include the bonding material. That is, in the above-described embodiments, the first groove C1, the second groove C2, the third groove C3, the fourth groove C4, and the fifth groove C5 may be through grooves.

[0134] In the embodiment of the present application, referring to FIG. 12 and FIG. 13 , the functional backplane 10 further includes: a second connecting trace 208 , a second flexible circuit board 209 and a second bonding structure (not shown in the figures).

[0135] One end of the second connecting trace 208 is located on the first surface 201a of the substrate 201 and is connected to the electronic component 202. The other end of the second connecting trace 208 is bent from the second surface 201d of the substrate 201 and is located on the second surface 201b of the substrate 201. The second surface 201d is opposite to the first side surface 201c.

[0136] The second flexible circuit board 209 is located on the second surface 201b of the substrate 201, away from the electronic component 202. The second flexible circuit board 209 is spaced apart from the first flexible circuit board 204 in the first direction X. A second bonding structure is located between the substrate 201 and the second flexible circuit board 209. The second flexible circuit board 209 is fixed to the second surface 201b of the substrate 201 by the second bonding structure. Furthermore, the second flexible circuit board 209 is connected to the other end of the second connecting trace 208. The second flexible circuit board 209 is also connected to a second external circuit structure. The second flexible circuit board 209 is used to transmit the second drive signal provided by the second external circuit structure to the electronic component 202 via the second connecting trace 208.

[0137] Optionally, the second flexible circuit board 209 includes a fourth conductive structure. Specifically, instead of dividing the second flexible circuit board 209 into regions with a single-layer conductive structure and regions with a double-layer conductive structure, all regions of the second flexible circuit board 209 are designed with a single-layer conductive structure. Consequently, no special structural design is required for the second bonding structure, and the thickness of each region of the second bonding structure is uniform. In other words, the second bonding structure does not require a design target portion 205a.

[0138] Of course, to prevent the substrate 201 from warping in the area where the second flexible circuit board 209 is located, the second bonding structure can also be designed with reference to the first bonding structure 205, that is, by designing grooves to provide expansion space for the bonding material. The embodiment of the present application does not limit the specific implementation of the second bonding structure.

[0139] Furthermore, the functional backplane 10 also includes a plurality of third connection pads 210 located on the first surface 201a of the substrate 201, and a plurality of fourth connection pads 211 located on the second surface 201b of the substrate 201 and corresponding one-to-one with the plurality of third connection pads 210. Furthermore, the functional backplane 10 also includes a plurality of second connection traces 208 corresponding to the plurality of third connection pads 210 and the plurality of fourth connection pads 211. Each second connection trace 208 has one end connected to the electronic component 202 via a corresponding third connection pad 210, and the other end connected to the second flexible circuit board 209 via a corresponding fourth connection pad 211.

[0140] Optionally, the plurality of third connection pads 210 are spaced apart in the second direction Y, and the plurality of fourth connection pads 211 are spaced apart in the second direction Y, thereby avoiding short circuits between different electrodes.

[0141] In the embodiment of the present application, both the first flexible circuit board 204 and the second flexible circuit board 209 include a main body structure and a branch structure. For each of the first flexible circuit board 204 and the second flexible circuit board 208, because the ends of the branch structures of the flexible circuit boards away from the side need to be connected to the external circuit structure, the bonding structure cannot be located in the area where the branch structures of the flexible circuit boards are located. For example, for the first flexible circuit board 204, the orthographic projection of the first bonding structure 205 on the first flexible circuit board 204 can be located in the area where the main body structure of the first flexible circuit board 204 is located, and not in the area where the branch structures of the first flexible circuit board 204 are located.

[0142] Furthermore, in the embodiment of the present application, the first flexible circuit board 204 has a first region 204a and a second region 204b, which may mean that both the main structure and the branch structure of the first flexible circuit board 204 have a first region and a second region. In other words, both the main structure and the branch structure of the first flexible circuit board 204 have a region with a single-layer conductive structure and a region with a double-layer conductive structure.

[0143] As shown in Figure 12, the first flexible circuit board 204 includes a first branch structure Z1 and a second branch structure Z2, and the second flexible circuit board 209 includes a third branch structure Z3. The ends of the first branch structure Z1 and the second branch structure Z2 away from the first side surface 201c can be used to connect to the first external circuit structure, and the end of the third branch structure Z3 away from the second side surface 201d can be used to connect to the second external circuit structure.

[0144] Referring to Figures 20 and 22 , the first flexible circuit board 204 includes a first conductive layer a1, an insulating layer a3, and a second conductive layer a2, stacked in sequence. The first flexible circuit board 204 has a first region 204a and a second region 204b. A first conductive structure 2041 is located in the first region 204a, while a second conductive structure 2042 and a third conductive structure 2043 are located in the second region 204b. Specifically, the first conductive structure 2041 can be located in either the first conductive layer a1 or the second conductive layer a2, the second conductive structure 2042 is located in one of the first conductive layer a1 and the second conductive layer a2, and the third conductive structure 2043 is located in the other of the first conductive layer a1 and the second conductive layer a2.

[0145] The first conductive structure 2041 may include multiple first signal lines 20411, one end of each first signal line 20411 being connected to the other end of the first connecting trace. Some of the multiple first signal lines 20411 are connected to the second conductive structure 2042, while other portions of the multiple first signal lines 20411 are connected to the third conductive structure 2043. At least one first signal line 20411 may be disposed on the same layer as the second conductive structure 2042, and some of the multiple first signal lines 20411 may be directly connected to the second conductive structure 2042. At least one first signal line 20411 is connected to the third conductive structure 2043 via a via in the insulating layer a3. Alternatively, at least one first signal line 20411 may be disposed on the same layer as the third conductive structure 2043, and at least one first signal line 20411 may be directly connected to the third conductive structure 2043, and at least one first signal line 20411 is connected to the second conductive structure 2042 via a via in the insulating layer a3.

[0146] In this embodiment of the present application, the second conductive structure 2042 of the first flexible circuit board 204 is located on the first conductive layer a1, and the third conductive structure 2043 is located on the second conductive layer a2. An insulating layer a3 is located between the first and second conductive layers a1 and a2. The second conductive structure 2042 specifically includes a first signal portion a11, a second signal portion a12, and a third signal portion a13; the third conductive structure 2043 specifically includes a fourth signal portion a21 and a fifth signal portion a22. The first, third, and fourth signal portions a11, a13, and a21 are each configured to transmit a third constant voltage signal, which may be a ground signal. The second signal portion a12 is configured to transmit a first constant voltage signal, and the fifth signal portion a22 is configured to transmit a second constant voltage signal. Both the first and second constant voltage signals may be high-level signals.

[0147] Optionally, each of the first signal portion a11 , the second signal portion a12 , the third signal portion a13 , the fourth signal portion a21 and the fifth signal portion a22 is a sheet-like structure, and different signal portions are spaced apart from each other.

[0148] In the embodiment of the present application, referring to FIG. 23 , multiple first signal lines 20411 are located in the first conductive layer a1 as an example. The multiple first signal lines 20411 include a first sub-signal line L1, a second sub-signal line L2, and a third sub-signal line L3. The first sub-signal line L1 can be directly connected to the second signal portion a12 of the first conductive layer a1. The second sub-signal line L2 is connected to the fifth signal portion a22 of the second conductive layer a2 via a via in the insulating layer a3. The third sub-signal line L3 is connected to the fourth signal portion a21 of the second conductive layer a2 via a via in the insulating layer a3.

[0149] Referring to Figure 20 , the first conductive layer a1 includes two first signal portions a11, two second signal portions a12, and two third signal portions a13. Each first signal portion a11 and each third signal portion a13 is configured to transmit a third constant voltage signal. Referring to Figure 20 , a gap exists between the third signal portion a13 and the first signal portion a11 of the second branch structure Z2. This gap can be used to set up test traces, which are located on the first conductive layer a1.

[0150] 21 , the second conductive layer a2 includes a fourth signal portion a21 and two fifth signal portions a22 , wherein the fifth signal portion a22 is T-shaped, and the fourth signal portion a21 surrounds the fifth signal portion a22 to form an integral structure.

[0151] In the embodiment of the present application, referring to Figure 24, the second signal portion a12 has a first sub-portion a121 located between the first signal portion a11 and the third signal portion a13, a second sub-portion a122 located in the first signal portion a11 close to the first area 204a, and a third sub-portion a123 located in the third signal portion a13 close to the first area 204a.

[0152] The third sub-signal line L3 located on the first conductive layer a1 is connected to the fourth signal portion a21 located on the second conductive layer a2. The first signal portion a11, the third signal portion a13, and the fourth signal portion a21 are all used to transmit a third constant voltage signal. The third sub-signal line L3 is connected to the fourth signal portion a21 of the second conductive layer a2 via a via in the insulating layer a3, thereby enabling the fourth signal portion a21 to transmit the third constant voltage signal. Furthermore, since the first signal portion a11 and the third signal portion a13 located on the first conductive layer a1 both have an area facing the fourth signal portion a21 located on the second conductive layer a2, vias can be provided at specific locations on the insulating layer a3 between the first conductive layer a1 and the second conductive layer a2. This allows the first signal portion a11 and the third signal portion a13 to be connected to the fourth signal portion a21 via the vias, thereby enabling the first signal portion a11 and the third signal portion a13 to transmit the third constant voltage signal.

[0153] Figure 25 is a partial enlarged schematic diagram of the dotted-line area in Figure 21 . Referring to Figure 25 , to connect the first flexible printed circuit board 204 to the first external circuit structure 300, the first region 204a of the first flexible printed circuit board 204 also includes an end region located between the first branch structure Z1 and the second branch structure Z2, away from the first side surface 201c. This end region includes a plurality of first strip electrodes R extending along the first direction X and arranged at equal intervals along the second direction Y. The first external circuit structure 300 is connected to the first flexible printed circuit board 204 via the plurality of first strip electrodes R. These plurality of first strip electrodes R are all located on the second conductive layer a2.

[0154] The first type of strip electrodes R1 and the fourth signal part a21 among the multiple first strip electrodes R are both located in the second conductive layer a2, so the two can be directly connected and form an integrated structure. The multiple second type of strip electrodes R2 and the fifth signal part a22 are both located in the second conductive layer a2, so the two can also be directly connected and form an integrated structure.

[0155] However, the third type of strip electrodes R3 among the multiple first strip electrodes R is connected to the second signal portion a12. Since the second signal portion a12 for transmitting the first constant voltage signal is located in the first conductive layer a1, the two need to be connected through the via V in the insulating layer a3.

[0156] It should be noted that in order to connect the plurality of first signal lines 20411 to the other end of the first connecting trace, the surface of the end of the first signal line 20411 close to the first side surface 201c needs to be exposed, and the exposed portion can constitute the second connecting pad 207. The first connecting trace 203 is directly in contact with the second connecting pad 207 to achieve connection.

[0157] 26 , the fourth conductive structure 2091 in the second flexible circuit board 209 may include multiple second signal lines 20911. One end of each second signal line 20911 is connected to the other end of the second connection trace 208, and the other end is connected to the second external circuit structure. This allows the second external circuit structure to transmit signals to the multiple second signal lines 20911.

[0158] The second flexible circuit board 209 comprises only one conductive layer, which includes a plurality of second signal lines 20911. To connect the plurality of second signal lines 20911 to the second connecting traces 208, the surfaces of the second signal lines at the ends near the second side surface 201d are exposed. This exposed portion can constitute the fourth connection pad 211. The first connecting trace 203 is directly connected to the fourth connection pad 211. Furthermore, the second flexible circuit board 209 includes a plurality of second strip electrodes located at the end of the third branch structure Z3 away from the second side surface 201d, extending along the first direction X and arranged at equal intervals along the second direction Y. The second external circuit structure is connected to the second flexible circuit board 209 via the plurality of second strip electrodes.

[0159] In summary, the embodiment of the present application provides a functional backplane, in which a first flexible circuit board is fixedly arranged on the second surface of the substrate in the display panel through a first bonding structure. The first flexible circuit board has a first region with a single-layer conductive structure and a second region with a double-layer conductive structure. Compared with the single-layer conductive structure, the double-layer conductive structure has a higher proportion of conductive material per unit space. Therefore, during high temperature processes, the expansion of the second region of the double-layer conductive structure is greater than the expansion of the first region of the single-layer conductive structure, and the difference between the expansion of the first bonding structure and the expansion of the first bonding structure is greater. The present application designs the thickness of the target portion located in the second region of the first bonding structure to be smaller, which can provide expansion space for the expansion of the bonding material of the first bonding structure, thereby reducing the total expansion of the first bonding structure. This can avoid the expansion of the first bonding structure being too large, resulting in a large difference in expansion with the second region of the first flexible circuit board, thereby avoiding the possibility of warping of the functional backplane and improving the yield of the functional backplane.

[0160] In the second embodiment, the present application further provides a functional backplane. The design of the substrate 201, electronic components 202, first connecting traces 203, and first flexible circuit board 204 in the functional backplane 10 is the same as that of the first embodiment. The difference lies in the design of the first bonding structure 205.

[0161] In the embodiment of the present application, referring to FIG. 27 , the first conformable structure 205 includes a first portion 2051 located in the first region 204a and a second portion 2052 located in the second region 204b. The difference in the coefficient of thermal expansion (CTE) of the material of the second portion 2052 and the CTE of the material of the first conductive structure 2041 (or the second conductive structure 2042) in the first flexible circuit board 204 is less than 3 ppm / °C.

[0162] That is, in the embodiment of the present application, in the second region 204b of the double-layer conductive structure, the second portion 2052 of the first bonding structure 205 can use a high-viscosity (viscosity ≥ 1000gf) pressure-sensitive adhesive with a relatively small thermal expansion coefficient, thereby reducing the difference in thermal expansion coefficient between the second region 204b of the first flexible circuit board 204 and the second portion 2052 of the first bonding structure 205, thereby avoiding warping of the substrate 201 caused by excessive difference in expansion at high temperatures.

[0163] Optionally, the material of the first conductive structure 2041 and the second conductive structure 2042 is copper, which has a coefficient of thermal expansion of 17.8 ppm / °C. The coefficient of thermal expansion (CTE) of the material of the second portion 2052 is less than or equal to 20 ppm / °C. This ensures that the difference between the CTE of the material of the second portion 2052 and the CTE of the material of the first conductive structure 2041 (or the second conductive structure 2042) in the first flexible circuit board 204 is less than 3 ppm / °C.

[0164] The embodiment of the present application does not impose any specific restrictions on the material of the second portion 2052 of the first bonding structure 205 . The material only needs to satisfy the requirements of a coefficient of thermal expansion (CTE) less than or equal to 20 ppm / ° C. and an adhesive force greater than or equal to 1000 gf.

[0165] The material of the second portion 2052 is different from the material of the first portion 2051, and the coefficient of thermal expansion (CTE) of the material of the second portion 2052 is smaller than the coefficient of thermal expansion (CTE) of the material of the first portion 2051. In this case, because the first region 204a of the single-layer conductive structure of the first flexible circuit board 204 contains a relatively small amount of copper, and the second region 204b of the double-layer conductive structure contains a relatively large amount of copper, the CTE of the first region 204a is larger than the CTE of the second region 204b.

[0166] Therefore, by designing the thermal expansion coefficient of the material of the second portion 2052 to be smaller than the thermal expansion coefficient of the material of the first portion 2051, the thermal expansion coefficient (CTE) of the material of the second portion 2052 can be made close to the thermal expansion coefficient (CTE) of the second region 204b, and the thermal expansion coefficient (CTE) of the material of the first portion 2051 can be made close to the thermal expansion coefficient (CTE) of the first region 204a. This design can prevent warping of the substrate 201 caused by a large difference in the expansion of the two regions at high temperatures.

[0167] In the embodiment of the present application, other relevant features of the substrate 201 , the electronic component 202 , the first connecting trace 203 and the first flexible circuit board 204 can refer to the detailed description of the first solution above, and the embodiment of the present application will not be repeated here.

[0168] In summary, an embodiment of the present application provides a functional backplane, in which a first flexible circuit board is fixedly arranged on the second surface of a substrate in a display panel through a first bonding structure. The first flexible circuit board has a first region of a single-layer conductive structure and a second region of a double-layer conductive structure. Since the double-layer conductive structure has a higher proportion of conductive material per unit space than the single-layer conductive structure, the expansion amount of the second region of the double-layer conductive structure during high temperature is greater than the expansion amount of the first region of the single-layer conductive structure, and is more different from the expansion amount of the first bonding structure. The difference between the thermal expansion coefficient of the second part of the first bonding structure located in the second region and the thermal expansion coefficient of the material of the first flexible circuit board is less than 3ppm / °C, which can avoid the expansion amount of the first bonding structure and the expansion amount of the second region of the first flexible circuit board being too different, thereby avoiding the possibility of warping of the functional backplane and improving the yield of the functional backplane.

[0169] In an embodiment of the present application, a method for preparing a functional backplane includes:

[0170] Step S1 : forming a driving film layer and pads on the first surface 201 a of the substrate 201 , and forming a film layer for connecting the first connection pad 206 and the third connection pad 210 to be conductively connected by the first connection trace 203 and the second connection trace 208 .

[0171] To minimize trace resistance and effective connection area, the length of the first connection pad 206 and the second connection pad 207 ranges from 0.08 mm to 0.2 mm, and their width is greater than 0.06 mm. The length of the connection pads corresponds to the alignment of the first and second regions 204 a, 204 b on the first flexible circuit board 204, while the width is perpendicular to the alignment of the first and second regions 204 a, 204 b.

[0172] Step S2: cutting off the process edge of the substrate 201 according to the required size of the final product to obtain a size suitable for splicing.

[0173] Typically, when the substrate 201 is manufactured, the product size is not the final required size, and is generally 5 mm or more larger. Therefore, the process edge needs to be cut off to obtain the final product size.

[0174] Step S3 : attaching the first flexible circuit board 204 to the second surface 201 b of the substrate 201 using the first bonding structure 205 , and attaching the second flexible circuit board 209 to the second surface 201 b of the substrate 201 using the second bonding structure.

[0175] Among them, the second connection pad 207 connected to the first flexible circuit board 204 corresponds one-to-one with the first connection pad 206 of the first surface 201a in the second direction Y, and the fourth connection pad 211 connected to the second flexible circuit board 209 corresponds one-to-one with the third connection pad 210 of the first surface 201a in the second direction Y, thereby facilitating the connection between the first connection pad 207 of the first surface 201a and the second connection pad 207 of the second surface 201b through the first connection trace 203, and facilitating the connection between the third connection pad 210 of the first surface 201a and the fourth connection pad 211 of the second surface 201b through the second connection trace 208.

[0176] By designing the first flexible printed circuit board 204 on the second surface 201b of the substrate 201, a first signal line connected to the first connecting trace 203 can be easily retracted. Furthermore, by designing the second flexible printed circuit board 209 on the second surface 201b of the substrate 201, a second signal line connected to the second connecting trace 2083 can be easily retracted.

[0177] Referring to FIG. 26 , taking the second flexible printed circuit board 209 as an example, the portion of the second signal line close to the side surface 201c of the substrate 201 occupies a greater length in the second direction Y. After winding, the portion of the second signal line away from the side surface of the substrate 201 occupies a smaller length in the second direction Y. In other words, the winding design can reduce the space occupied by the signal line in the second direction Y.

[0178] Step S4 : forming the first connection trace 203 and the second connection trace 208 by printing, thereby achieving conduction between the first connection pad 206 and the second connection pad 207 , and achieving conduction between the third connection pad 210 and the fourth connection pad 211 .

[0179] Optionally, the materials of the first connection wire 203 and the second connection wire 208 may both be metals, such as copper (Cu), titanium (Ti), silver (Ag), aluminum (Al), or alloys thereof.

[0180] Step S5: performing high-temperature curing treatment on the first connecting wire 203 and the second connecting wire 208 .

[0181] The temperature during the high-temperature curing treatment of the first connection trace 203 and the second connection trace 208 can be greater than or equal to 150° C., and the time can be greater than or equal to 30 minutes.

[0182] Step S6: forming a protective layer.

[0183] A protective layer is formed by printing on the side of the first connecting wire 203 and the second connecting wire 208 away from the substrate 201 to prevent scratches and bumps from damaging the wires and causing defects.

[0184] Step S7: performing high-temperature curing treatment on the protective layer.

[0185] When performing high-temperature curing on the protective layer, the temperature is gradually increased from below 60°C to 150°C. Furthermore, if the temperature is above 150°C, it must be maintained at this temperature for at least 30 minutes. This means that the temperature must be ≥ 150°C and the time must be ≥ 30 minutes.

[0186] Step S8: Use a light emitting diode (LED) to perform die bonding on the first surface 201a of the substrate 201 to achieve connection between the LED and the pad.

[0187] Step S9 : Bind and connect the first external circuit structure 300 and the first flexible circuit board 204 , and bind and connect the second external circuit structure and the second flexible circuit board 209 .

[0188] The first external circuit structure 300 and the second external circuit structure can be used to provide different drive signals. Optionally, the first external circuit structure 300 is used to provide a power supply signal. The second external circuit structure is used to transmit a display signal (which can be understood as a signal that tells it what pattern to display, or a data signal).

[0189] Step S10: blackening and encapsulating the first surface 201a of the substrate 201 to obtain an encapsulation layer, thereby achieving effects such as increased contrast and uniform display.

[0190] The terms used in the embodiments of this application are only used to explain the embodiments of this application and are not intended to limit this application. Unless otherwise defined, the technical terms or scientific terms used in the embodiments of this application should have the common meaning understood by people with ordinary skills in the field to which this application belongs.

[0191] The terms used in the embodiments of this application are intended solely to illustrate the embodiments of this application and are not intended to limit this application. Unless otherwise defined, technical or scientific terms used in the embodiments of this application should have the same ordinary meaning as those understood by persons of ordinary skill in the art to which this application belongs. The terms "first," "second," "third," and similar terms used in this patent specification and claims do not denote any order, quantity, or importance, but are simply used to distinguish between different components. Similarly, terms such as "a" or "an" do not denote a limitation of quantity, but rather denote the presence of at least one. Terms such as "include" or "comprising" and similar terms mean that the elements or objects listed before "include" or "comprising" include the elements or objects listed after "include" or "comprising," and their equivalents, and do not exclude other elements or objects. Terms such as "connected" or "connected" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used solely to indicate relative positions. When the absolute position of the described objects changes, the relative positions may also change accordingly.

[0192] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A functional backplane, characterized in that: The functional backplane (200) comprises: substrate(201); A plurality of electronic components (202) located on a first surface (201a) of the substrate (201); A first connecting wire (203), one end of the first connecting wire (203) being located on a first surface (201a) of the substrate (201) and connected to the electronic component (202), and the other end of the first connecting wire (203) being bent from the first surface (201c) of the substrate (201) and being located on a second surface (201b) of the substrate (201); a first flexible circuit board (204) and a first bonding structure (205), wherein the first flexible circuit board (204) is located on a second surface (201b) of the substrate (201) away from the plurality of electronic components (202), the first bonding structure (205) is located between the substrate (201) and the first flexible circuit board (204), the first flexible circuit board (204) is fixedly arranged on the second surface (201b) of the substrate (201) through the first bonding structure (205), the first flexible circuit board (204) is connected to the other end of the first connecting wire (203), the first flexible circuit board (204) is also connected to a first external circuit structure (300), and the first flexible circuit board (204) is used to transmit a first driving signal provided by the first external circuit structure (300) to the electronic component (202) through the first connecting wire (203); The first flexible circuit board (204) has a first area (204a) and a second area (204b), and the first flexible circuit board (204) includes a first conductive structure (2041) located in the first area (204a), and a second conductive structure (2042) and a third conductive structure (2043) located in the second area (204b) and stacked; the first bonding structure (205) has a plurality of target portions (205a) in a strip shape located at least in the second area (204b), and the thickness of the target portion (205a) of the first bonding structure (205) is less than the thickness of other portions of the first bonding structure (205) except the target portion (205a).

2. The functional backplane according to claim 1, characterized in that: The plurality of target portions (205a) include a plurality of first grooves (C1) extending along a first direction (X) and spaced apart in a second direction (Y); The first direction (X) is the arrangement direction of the first region (204a) and the second region (204b), and the second direction (Y) is perpendicular to the first region (204a) and the second region (204b). The arrangement direction.

3. The functional backplane according to claim 2, characterized in that: The plurality of target portions (205a) further include a plurality of second grooves (C2) extending along the second direction (Y) and spaced apart in the second direction (Y); At least some of the second grooves (C2) among the plurality of second grooves (C2) are in communication with the first groove (C1).

4. The functional backplane according to claim 3, characterized in that: The plurality of second grooves (C2) are located in the middle of the second area (204b) in the first direction (X).

5. The functional backplane according to claim 3, characterized in that: The spacing between two adjacent first grooves (C1) along the second direction (Y) and the spacing between two adjacent second grooves (C2) along the second direction (Y) are both greater than or equal to 10 mm; The width of the first groove (C1) ranges from 1 mm to 5 mm, the length of the first groove (C1) is equal to the length of the second area (204b) along the first direction (X), the width of the second groove (C2) ranges from 0.5 mm to 2 mm, and the length of the second groove (C2) is less than the spacing between two adjacent second grooves (C2) along the second direction (Y).

6. The functional backplane according to claim 2, characterized in that: The plurality of target portions (205a) further include a third groove (C3) extending along a second direction (Y), wherein a length of the third groove (C3) in the second direction (Y) is equal to a length of the first fitting structure (205) in the second direction (Y); Wherein, the third groove (C3) is located at the boundary between the first area (204a) and the second area (204b).

7. The functional backplane according to claim 1, characterized in that: The plurality of target portions (205a) include a plurality of fourth grooves (C4) extending along the first direction (X) and arranged at intervals in the second direction (Y), and a plurality of fifth grooves (C5) extending along the second direction (Y) and arranged at intervals in the first direction (X); Wherein, the plurality of fourth grooves (C4) and the plurality of fifth grooves (C5) form a grid shape.

8. The functional backplane according to claim 7, characterized in that: The widths of the fourth groove (C4) and the fifth groove (C5) are both in the range of 100 microns to 150 microns, and the spacing between two adjacent fourth grooves (C4) in the second direction (Y) and the spacing between two adjacent fifth grooves (C5) in the first direction (X) are both greater than or equal to 300 microns.

9. The functional backplane according to claim 7, characterized in that: The plurality of fourth grooves (C4) and the plurality of fifth grooves (C5) are also located in the first region (204a).

10. The functional backplane according to any one of claims 1 to 9, characterized in that: The first bonding structure (205) includes a bonding material, and other parts of the first bonding structure (205) except the target part (205a) are the parts of the first bonding structure (205) having the bonding material, and the target part (205a) of the first bonding structure (205) is the part of the first bonding structure (205) not having the bonding material.

11. A functional backplane, characterized in that: The functional backplane (200) comprises: substrate(201); A plurality of electronic components (202) on a first surface (201a) of the substrate (201); A first connecting wire (203), one end of the first connecting wire (203) being located on a first surface (201a) of the substrate (201) and connected to the electronic component (202), and the other end of the first connecting wire (203) being bent from the first surface (201c) of the substrate (201) and being located on a second surface (201b) of the substrate (201); a first flexible circuit board (204) and a first bonding structure (205), wherein the first flexible circuit board (204) is located on a second surface (201b) of the substrate (201) away from the plurality of electronic components (202), the first bonding structure (205) is located between the substrate (201) and the first flexible circuit board (204), the first flexible circuit board (204) is fixedly arranged on the second surface (201b) of the substrate (201) through the first bonding structure (205), the first flexible circuit board (204) is connected to the other end of the first connecting wire (203), the first flexible circuit board (204) is also connected to a first external circuit structure (300), and the first flexible circuit board (204) is used to transmit a first driving signal provided by the first external circuit structure (300) to the electronic component (202) through the first connecting wire (203); The first flexible circuit board (204) has a first region (204a) and a second region (204b), the first flexible circuit board (204) comprises a first conductive structure (2041) located in the first region (204a), and a second conductive structure (2042) and a third conductive structure (2043) located in the second region (204b) and stacked, the first conductive structure (2041), the second conductive structure (2042) and the third conductive structure (2043) being made of the same material; the first bonding structure (205) comprises a first portion (2051) located in the first region (204a) and a second portion (2052) located in the second region (204b), the difference between the thermal expansion coefficient of the material of the second portion (2052) and the thermal expansion coefficient of the material of the first conductive structure (2041) being less than 1 part per million per degree Celsius.

12. The functional backplane according to claim 11, characterized in that: The first conductive structure (2041), the second conductive structure (2042) and the third conductive structure (2043) are all made of copper; The coefficient of thermal expansion of the material of the second portion (2052) is less than or equal to 20 parts per million per degree Celsius.

13. The functional backplane according to claim 11, characterized in that: The material of the second part (2052) is different from the material of the first part (2051), and the thermal expansion coefficient of the material of the second part (2052) is smaller than the thermal expansion coefficient of the material of the first part (2051).

14. The functional backplane according to any one of claims 1 to 9 and 11 to 13, characterized in that: The functional backplane (200) further comprises: A second connecting wire (208), one end of the second connecting wire (208) being located on the first surface (201a) of the substrate (201) and connected to the electronic component (202), the other end of the second connecting wire (208) being bent from the second surface (201d) of the substrate (201) and being located on the second surface (201b) of the substrate (201), the second surface (201d) and the first surface (201c) being located opposite to each other; A second flexible circuit board (209) and a second bonding structure, wherein the second flexible circuit board (209) is located on a second surface (201b) of the substrate (201) away from the electronic component (202), and the second flexible circuit board (209) and the first flexible circuit board (204) are spaced apart in a first direction (X), and the second bonding structure is located between the substrate (201) and the second flexible circuit board (209). The second flexible circuit board (209) is fixedly arranged on the second surface (201b) of the substrate (201) through the second bonding structure, the second flexible circuit board (209) is connected to the other end of the second connecting wire (208), and the second flexible circuit board (209) is also connected to the second external circuit structure, and the second flexible circuit board (209) is used to transmit the second driving signal provided by the second external circuit structure to the electronic component (202) through the second connecting wire (208); The second flexible circuit board (209) comprises a fourth conductive structure, and the thickness of each region of the second bonding structure is the same.

15. A light emitting device, characterized in that: The light emitting device comprises: a power supply component and a functional backplane as claimed in any one of claims 1 to 14; Wherein, the power supply component is used to supply power to the functional backplane.

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