Electronic device back cover and electronic device

Abstract

This application provides a back cover for an electronic device and an electronic device. The back cover includes a first structural layer and a second structural layer. The first structural layer includes a first region and a second region, the thickness of the first region being greater than the thickness of the second region. The second structural layer is located on the outer surface of the first structural layer and is bonded to the first structural layer by an adhesive layer. The second region forms a projected orthographic projection along the thickness direction of the electronic device, and the battery of the electronic device forms a projected orthographic projection along the thickness direction of the electronic device. The projected orthographic projection of the second region includes the projected orthographic projection of the battery. This back cover is adaptable to the frame of an electronic device with a glass back cover.

Description

[0001] This application is a divisional application. The original application was entitled "Electronic Device Back Cover and Electronic Device", with application number 202110922162.0 and application date of August 12, 2021. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of terminal equipment, and more particularly to a back cover for an electronic device and an electronic device. Background Technology

[0003] Currently, some electronic devices use glass back covers. Glass back covers are thin, and to accommodate them, the frame height of most electronic devices on the market is correspondingly smaller. However, as users' demands for personalized electronic devices continue to increase, a single glass back cover can no longer meet their needs. To enhance the competitiveness of electronic devices in the market, it is necessary to develop back covers made of other materials. However, back covers made of other materials are thicker and cannot be fitted to the frames of electronic devices with glass back covers. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a back cover for an electronic device and an electronic device. In this method, a fiber composite material is used to fabricate the back cover of the electronic device. The back cover is made into a structure with unequal thickness, where the thickness bottleneck area directly opposite the battery portion of the electronic device is thin, and other non-thickness bottleneck areas are thicker. This indirectly reduces the thickness of the back cover, allowing it to fit with the glass back cover of the electronic device's frame.

[0005] In a first aspect, this application provides a back cover for an electronic device, comprising: a first structural layer including a first region and a second region, wherein the thickness of the first region is greater than the thickness of the second region; wherein the second region forms a second region orthographic projection along the thickness direction of the electronic device, and the battery of the electronic device forms a battery orthographic projection along the thickness direction of the electronic device, and the second region orthographic projection includes the battery orthographic projection. This method of fabricating the back cover with an unequal thickness structure—where the thickness bottleneck region directly opposite the battery portion of the electronic device is thin, and other non-thickness bottleneck regions are thick—effectively reduces the thickness of the back cover, enabling it to fit with the glass back cover of the electronic device's frame.

[0006] For example, in the electronic device back cover provided in the first aspect of this application, the first structural layer is a fiber composite board. The manufacturing process of this one-piece fiber composite board back cover is simple.

[0007] For example, the back cover of the electronic device provided in the first aspect of this application has a first region of fiber composite board and a second region of metal substrate; the back cover formed by combining the metal substrate and the fiber composite board can further reduce the overall thickness of the thickness bottleneck area, provided that the rigidity of the metal substrate meets the requirements.

[0008] For example, in the back cover of the electronic device provided in the first aspect of this application, the upper surfaces of the first region and the second region are located on the same horizontal plane; the overlapping area of ​​the first region and the second region is fixedly connected. The overlapping area can be located in the first region, or it can be located in the second region, or it can span across the first and second regions. The fixed connection of the overlapping area ensures the reliability of the connection between the first region and the second region.

[0009] For example, in the back cover of the electronic device provided in the first aspect of this application, the overlapping areas of the first region and the second region are fixed by adhesive bonding, or the precursor of the fiber composite board in the first region is thermoformed by hot pressing onto a metal substrate. The overlapping areas are fixed by adhesive bonding, which is a simple process and provides good adhesion. The precursor of the fiber composite board in the first region is thermoformed by hot pressing onto a metal substrate, and after curing, the fibers are bonded by molecular forces between the fiber composite board and the metal substrate, eliminating the need for adhesives.

[0010] For example, in the back cover of the electronic device provided in the first aspect of this application, the overlapping area of ​​the metal substrate and the fiber composite board is partially etched. Partial etching of the overlapping area of ​​the metal substrate and the fiber composite board can increase the bonding force between the fiber composite board and the metal substrate in the overlapping area.

[0011] For example, in the back cover of the electronic device provided in the first aspect of this application, a hole is partially cut in the overlapping area of ​​the metal substrate and the fiber composite board. This localized hole design in the overlapping area of ​​the metal substrate and the fiber composite board can increase the bonding force between the fiber composite board and the metal substrate in the overlapping area.

[0012] For example, the thickness of the metal substrate in the first structural layer of the electronic device back cover provided in the first aspect of this application ranges from 0.15mm to 0.3mm. Setting the thickness of the metal substrate to 0.15mm to 0.3mm, while ensuring the rigidity of the metal substrate, can further reduce the overall thickness of the thickness bottleneck area. For example, the first region of the first structural layer provided in the first aspect of this application is the region bonded and fixed to the electronic device's frame. In this optional embodiment, only the thickness of the region bonded and fixed to the frame in the first structural layer is increased, making the projected area of ​​the second region along the thickness direction of the electronic device larger, thereby providing more internal space for the electronic device. With this type of back cover featuring an unequal thickness first structural layer, the region bonded and fixed to the electronic device's frame at the edge of the back cover is thin, allowing it to adapt to the outer contour of the frame that is compatible with the glass back cover.

[0013] For example, the first region of the first structural layer provided in the first aspect of this application has a gradually varying thickness, wherein the thickness of the first region increases with distance from the outer edge of the frame. Designing the first region as a structure with a gradually varying thickness allows for a more personalized and diverse shape for the back cover of electronic devices.

[0014] For example, the thickness of the outer edge of the adhesive area of ​​the back cover of the electronic device provided in the first aspect of this application ranges from 0.15mm to 0.45mm, which enables the back cover of the embodiment of this application to be adapted to the same electronic device frame as the glass back cover.

[0015] For example, the back cover of the electronic device provided in the first aspect of this application further includes: a second structural layer; the second structural layer is located on the outer surface of the first structural layer. Providing the second structural layer on the outer surface of the first structural layer can protect the first structural layer or modify the back cover.

[0016] For example, the second structural layer provided in the first aspect of this application is a cover layer, which is bonded to the first structural layer by an adhesive layer. The cover layer is disposed on the outer surface of the first structural layer, which can improve the aesthetics of the back cover and enhance the grip feel of the electronic device. For example, the adhesive layer can be double-sided tape or an adhesive, and the adhesive bonding process is simple and low-cost. For example, the electronic device back cover provided in the first aspect of this application includes cover layers such as vegan leather, genuine leather, and bamboo veneer; different cover layers have different feel and appearance, and different styles of electronic device back covers can be prepared.

[0017] For example, in the electronic device back cover provided in the first aspect of this application, the thickness of the third region of the cover layer covering the first structural layer gradually changes. The third region is a predetermined distance from the outer edge of the frame, and is a partial region of the cover layer after hot stamping with a hot stamping mold. The thickness of the third region increases as it moves further from the outer edge of the frame. Thinning the cover layer at the outer edge of the back cover results in a thinner thickness at the edge of the back cover, allowing for a better fit with the glass back cover of the electronic device frame.

[0018] For example, in the electronic device back cover provided in the first aspect of this application, a protrusion is provided on the first structural layer near the outer edge of the middle frame, and the upper surface of the protrusion smoothly transitions with the upper surface of the third region of the cover layer after embossing. Protrusions at the edge of the first structural layer can engage the embossed cover layer, improving the adhesion between the cover layer and the first structural layer. Furthermore, the smooth transition between the upper surface of the protrusion and the upper surface of the third region of the cover layer after embossing improves the smoothness of the outer surface of the back cover. This method of hot stamping a localized area of ​​the 2D back cover's outer surface cover layer can create a 2.5D effect for the back cover.

[0019] For example, the entire cover layer provided in the first aspect of this application is hot-stamped using a hot stamping mold. On one hand, hot stamping the entire cover layer can further reduce its thickness, thereby reducing the overall thickness of the back cover. On the other hand, pre-defined patterns can be prepared on the cover layer through overall hot stamping, enhancing the aesthetics of the back cover.

[0020] For example, the cover layer provided in the first aspect of this application is of uniform thickness. The manufacturing process of a uniform thickness cover layer is simple.

[0021] For example, the first structural layer provided in the first aspect of this application has a protrusion near the outer edge of the middle frame, and the upper surface of the protrusion smoothly transitions with the upper surface of the cover layer after it is imprinted. Protrusions at the edge of the first structural layer can engage the imprinted cover layer, improving the adhesion between the cover layer and the first structural layer. The smooth transition between the upper surface of the protrusion and the upper surface of the cover layer after it is imprinted enhances the smoothness of the outer surface of the back cover.

[0022] For example, in the electronic device back cover provided by the first aspect of this application, the second structural layer is a ceramic layer, which covers the outer surface of the first structural layer. The first structural layer is configured as a structure with unequal thickness. This structure, which combines the ceramic layer with the first structural layer with unequal thickness, can, on the one hand, reduce the processing accuracy of the ceramic layer bonding surface; on the other hand, it can enhance the rigidity of the four corners of the ceramic back cover, thereby improving the overall reliability of the ceramic back cover.

[0023] For example, in the electronic device back cover provided in the first aspect of this application, the adhesive surface of the first structural layer is bonded to the inner surface of the ceramic layer by a hot-pressing process. Hot-pressing bonding results in good stability at the bonded joint.

[0024] For example, in the back cover of the electronic device provided in the first aspect of this application, the inner surfaces of the first structural layer and the ceramic layer are bonded together by an adhesive layer, wherein the adhesive layer is double-sided tape or adhesive, and the bonding process of bonding the two structural layers together by the adhesive layer is simple and low cost.

[0025] For example, the back cover of the electronic device provided in the first aspect of this application has a ceramic layer covering the outer surface of the first structural layer. The second region of the first structural layer has a thickness of 0, that is, the first structural layer is a structure with a hollow center and a thickness around the edges. The first structural layer of this structure is attached to the inside of the ceramic layer, which can improve the rigidity of the four corners of the ceramic back cover, thereby improving the overall reliability of the ceramic back cover.

[0026] For example, the second structural layer included in the back cover of the electronic device provided in the first aspect of this application is a decorative layer. The decorative layer is a coating, and the coating preparation process is simple and the coating is firm and not easily peeled off from the first structural layer. The decorative layer disposed on the outer surface of the first structural layer can serve a decorative function for the back cover.

[0027] Secondly, this application provides an electronic device, which includes: a mid-frame, a display screen, and any of the electronic device back covers described in the first aspect. Attached Figure Description

[0028] Figure 1 A schematic diagram of the hardware structure of an electronic device as an example;

[0029] Figure 2 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0030] Figure 3 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0031] Figure 4 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0032] Figure 5 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0033] Figure 6 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0034] Figure 7 This is a schematic diagram of the structure of the back cover of an electronic device, as exemplarily shown.

[0035] Figure 8 This is an exemplary schematic diagram of the thickness gradient of a fiber composite board;

[0036] Figures 9a to 9b This is a schematic diagram illustrating the partial hot stamping process of vegan leather;

[0037] Figures 10a to 10c This is a schematic diagram illustrating the overall hot stamping process of vegan leather;

[0038] Figures 11a to 11b A schematic diagram illustrating the hot stamping process of a 2D back cover;

[0039] Figure 12 This is a schematic diagram illustrating the structure of a ceramic back cover for an electronic device, as an example.

[0040] Figure 13 This is a schematic diagram of the structure of a ceramic back cover for an electronic device, as an example. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0043] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0044] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0045] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0046] Figure 1 A schematic diagram of the electronic device is shown. It should be understood that... Figure 1 The electronic device shown is merely an example of an electronic device, and electronic devices may have more or fewer components than those shown in the figure, may combine two or more components, or may have different component configurations. Figure 1 The various components shown can be implemented in hardware, software, or a combination of hardware and software, including one or more signal processing and / or application-specific integrated circuits.

[0047] In this application embodiment, the electronic device can be a mobile terminal such as a mobile phone, tablet computer, wearable device, vehicle-mounted device, augmented reality (AR) / virtual reality (VR) device, laptop computer, ultra-mobile personal computer (UMPC), netbook, personal digital assistant (PDA), etc. Alternatively, it can be a professional shooting device such as a digital camera, SLR camera / mirrorless camera, action camera, gimbal camera, drone, etc. This application embodiment does not limit the specific type of terminal device.

[0048] The embodiments of this application will be described below using a mobile phone as an example. Figure 1 As shown, the electronic device includes a display screen 101, a mid-frame 102, and a back cover 103. The display screen 101 and the back cover 103 are nested within the mid-frame, forming the outer casing structure of the electronic device. It should be noted that... Figure 1 This description merely illustrates the casing structure of an electronic device. In addition to this casing structure, the electronic device may also include internal hardware, a processor, an external memory interface, internal memory, a universal serial bus (USB) interface, a charging management module, a power management module, a battery, an antenna, a mobile communication module, a wireless communication module, an audio module, a speaker, a receiver, a microphone, a headphone jack, a sensor module, buttons, a motor, indicators, a camera, etc. The internal hardware listed above... Figure 1 Not shown in the image.

[0049] In this embodiment, the back cover 103 of the electronic device can adopt any of the structures shown in the subsequent embodiments, such as: a first structural layer structure with unequal thickness, a composite structure of a first structural layer with unequal thickness and a cover layer, a composite structure of a first structural layer with unequal thickness and a decorative layer, a composite structure of a fiber composite board with unequal thickness and a ceramic layer, etc., so that the back cover of the electronic device in this embodiment can be adapted to the electronic device frame with a glass back cover.

[0050] The following is combined Figure 2 A brief description of the back cover of the electronic device according to an embodiment of this application will be provided.

[0051] Figure 2The back cover 103 of the electronic device is defined in a three-dimensional X, Y, Z coordinate system. The positive Z-axis is the direction facing the outer surface of the back cover 103 (i.e., the rearward direction of the electronic device), and the negative Z-axis is the direction facing the inner surface of the back cover 103 (i.e., the forward direction of the electronic device). The thickness direction of the back cover is the Z-axis direction. The back cover 103 can be a single-layer structure or a multi-layer composite structure. A single-layer structure includes only a first structural layer, which can be a fiber composite board or a fiber composite board combined with a metal substrate. A multi-layer structure includes a first structural layer and a second structural layer. The first structural layer is located on the outer surface of the first structural layer, which can be a fiber composite board or a fiber composite board combined with a metal substrate. The second structural layer can include a cover layer, a decorative layer, and a ceramic layer. (See below for reference.) Figures 3 to 13 ,right Figure 2 The detailed structure of the back cover under the coordinate system defined in the document is explained.

[0052] The following explanation uses fiber composite board as the first structural layer as an example.

[0053] To balance the rigidity, thickness, and external surface morphology of the back cover and enhance its competitiveness, this application proposes a composite material electronic device back cover using a fiber composite board of unequal thickness as the substrate. The unequal thickness fiber composite board structure allows for significant reduction in back cover thickness, increased rigidity, and adaptation of the back cover's curved surface to the glass back cover's frame, achieving the goal of sharing a single frame with the glass back cover. Typically, the overall thickness of electronic devices is limited by certain locations, which become thickness bottlenecks. In this application, the back cover thickness is designed to be thinner in the thickness bottleneck areas, while in non-thickness bottleneck areas, due to the relatively sufficient gap beneath the inner surface of the back cover, protrusions can be designed on the inner surface of the back cover.

[0054] For example, refer to Figure 3 The schematic diagram of the back cover structure of the electronic device is shown below. Figure 3 The back cover of the electronic device is shown in a YZ cross-sectional view. The back cover 303 has an unequal thickness structure and can be a fiber composite board made of fiber-reinforced resin, a polyurethane substrate, a polyurethane fiber composite board, or an ABS resin substrate. In fiber-reinforced resin materials, fibers serve as the reinforcing material and resin as the matrix. Fiber-reinforced resin materials are characterized by high impact resistance, ease of processing, and high rigidity. ABS resin is one of the five major synthetic resins, possessing advantages such as impact resistance, heat resistance, low-temperature resistance, chemical resistance, ease of processing, dimensional stability, surface gloss, ease of coating, and ease of coloring. In this embodiment, the back cover will be described using a fiber composite board as an example. The back cover prepared from the fiber composite board will be referred to as the fiber composite back cover in the subsequent embodiment description.

[0055] Reference Figure 3 As shown, the back cover 303 is a fiber composite board structure with unequal thickness. The back cover 303 includes a first region 3031 and a second region 3032. The second region 3032 forms a second region orthographic projection along the thickness direction of the electronic device, and the battery 305 forms a battery orthographic projection along the thickness direction of the electronic device. The second region orthographic projection includes the battery orthographic projection. After the back cover 303 is placed in the electronic device's frame 302, the first region 3031, opposite to the battery 305, is a thickness bottleneck region used to accommodate thicker components such as the battery. The second region 3032, opposite to the motherboard 304 and the sub-board 306, is a non-thickness bottleneck region used to accommodate thinner components such as the motherboard and sub-board. The thickness of the first region in the back cover 303 is less than the thickness of the second region, and the upper surfaces of the first and second regions are on the same horizontal plane. In an optional embodiment, the thickness of the first region can be set to 0.2mm to 0.5mm. Setting the thickness of the first region to 0.2mm to 0.5mm satisfies the overall thickness reduction condition of the thickness bottleneck region while also meeting the rigidity requirements of the first region. The thickness of the second region can be flexibly set according to the height of the adapted mid-frame, motherboard, and sub-board; this application does not impose any restrictions on this. The second region is the region in the first structural layer other than the first region.

[0056] This exemplary back cover structure, on the one hand, helps to improve the overall rigidity of the back cover without changing the overall thickness of the electronic device; on the other hand, because the second area of ​​the back cover is thicker at the edges and thinner in the middle, the excess gap between the inner surface of the back cover and the motherboard and sub-board is reduced, which can reduce the overall pressing type of the electronic device and improve the grip of the back cover.

[0057] To improve the aesthetics and grip of electronic device back covers, one can also... Figure 3 The uneven thickness fiber composite layer shown is covered with a veneer. The following explanation uses an example where the first structural layer is an uneven thickness fiber composite board and the second structural layer is a veneer. For example, refer to... Figure 4 The schematic diagram of the back cover structure of the electronic device is shown below. Figure 4 The back cover of the electronic device is shown in a YZ cross-sectional diagram. The back cover is composed of a composite layer structure of unequal thickness fiber composite board 4031 and veneer leather 4032. The unequal thickness fiber composite board 4031 and veneer leather 4032 are bonded and fixed together by an adhesive layer 4033, which can be an adhesive filler or double-sided tape. The veneer leather 4032, as the covering layer of the back cover, serves both to protect the unequal thickness fiber composite board 4031 and to provide decoration. The veneer leather 4032 can also be replaced with polyurethane (PU), genuine leather, bamboo veneer, or other materials. Furthermore, the covering layer can also be a coating. The thickness of the veneer leather 4032 can be as follows... Figure 4 The structure shown is of uniform thickness, but it can also be of unequal thickness.

[0058] After the back cover of the electronic device is placed in the middle frame 402 of the electronic device, the first area of ​​the unequal thickness fiber composite board 4031 is opposite to the battery 405, and the second area of ​​the unequal thickness fiber composite board is opposite to the main board 404 and the sub-board 406 of the electronic device, respectively. The thickness of the first area is less than the thickness of the second area.

[0059] This optional method of covering the outer surface of the fiber composite board with a veneer improves both the aesthetics and the grip of the electronic device's back cover. Since the back cover 303 is a fiber composite board with unequal thickness, the thickness of the second region of the back cover 303 can be reduced to 0.2mm to 0.5mm due to the trade-off between the thickness and rigidity of the fiber composite board. To further reduce the thickness of the back cover, it can also be configured as a structure combining the fiber composite board and a metal substrate, replacing the second region of the fiber composite board with a metal substrate. This type of back cover includes a first structural layer, where the first region of the first structural layer is a fiber composite board and the second region is a metal substrate.

[0060] For example, refer to Figure 5 The schematic diagram of the back cover structure of the electronic device is shown below. Figure 5 The back cover of the electronic device is shown in a YZ cross-sectional view. The back cover is a single-layer structure with varying thicknesses, primarily composed of a first fiber composite board 5031, a metal substrate 5032, and a second fiber composite board 5033. The upper surfaces of the metal substrate 5032, the first fiber composite board 5031, and the second fiber composite board 5033 are on the same horizontal plane. The overlapping areas of the metal substrate 5032 and the first fiber composite board 5031, and the overlapping areas of the second fiber composite board 5033, are fixedly connected. After the back cover is placed in the electronic device's frame 502, the orthographic projection of the first fiber composite board 5031 in the thickness direction (Z direction) includes the orthographic projection of the motherboard 504 in the Z direction; the orthographic projection of the metal substrate 5032 in the Z direction includes the orthographic projection of the battery 505 in the Z direction; and the projection of the second fiber composite board 5033 includes the projection of the sub-board 506. The region corresponding to the metal substrate 5032 is a thickness bottleneck region, while the regions corresponding to the first fiber composite plate 5031 and the second fiber composite plate 5033 are non-thickness bottleneck regions. The thickness of the metal substrate 5032 is less than the thickness of the first fiber composite plate 5031 and the second fiber composite plate 5033.

[0061] The metal substrate may include, but is not limited to, stainless steel substrates, aluminum alloy substrates, etc. The thickness of the metal substrate can be set to 0.2mm to 0.5mm, or less than 0.2mm. In an optional embodiment, the thickness of the metal substrate is set to 0.15mm to 0.3mm. When the metal substrate serves as the second region of the first structural layer, and both the first fiber composite board and the second fiber composite board serve as the second regions of the first structural layer... Figure 5This example only illustrates one configuration where the overlapping area is located in the first region. In actual implementation, the overlapping area can be located in the second region or span both the first and second regions. The metal substrate 5032, the first fiber composite plate 5031, and the second fiber composite plate 5033 in the overlapping region can be bonded using adhesives such as glue or double-sided tape, or they can be joined using a metal-polymer splicing process, such as in-mold injection molding. For example, continue referring to... Figure 5 The overlapping areas of the metal substrate 5032 and the first fiber composite board 5031 are bonded and fixed by a first double-sided adhesive 5034, and the overlapping areas of the metal substrate 5032 and the second fiber composite board 5031 are bonded and fixed by a second double-sided adhesive 5035. In an optional embodiment, the bonding width of the first double-sided adhesive 5034 and the second double-sided adhesive 5035 is 0.7 to 3.5 mm, for example, the bonding width is the length along the Y-axis, and the adhesive layer thickness is 0.05 to 0.3 mm. When bonding the first fiber composite board 5031, the metal substrate 5032, and the second fiber composite board 5033 with adhesives, the bonding width can also be controlled to be 0.7 to 3.5 mm, and the adhesive layer thickness to be 0.05 to 0.3 mm. By controlling the bonding width and adhesive layer thickness within the above optional ranges, the influence of the adhesive layer thickness on the overall thickness of the electronic device can be minimized while ensuring bonding stability. Optionally, localized corrosion or hole drilling in the first and second regions of the lower surface of the metal substrate 5032 can increase the bonding force between the fiber composite board and the metal substrate.

[0062] In an optional embodiment, in addition to the method of bonding the overlapping areas of the first fiber composite board, the second fiber composite board, and the metal substrate with adhesive as listed above, the precursors of the first and second fiber composite boards can also be thermoformed by hot pressing them onto the metal substrate. After curing, an overlapping area is formed in the area where the first fiber composite board and the lower surface of the metal substrate contact each other, and an overlapping area is formed in the area where the second fiber composite board and the lower surface of the metal substrate contact each other. After curing, the fiber composite board and the metal substrate in the overlapping area are bonded by the molecular forces between the fiber composite board and the metal substrate, without the need for adhesive. The precursor is a form existing before obtaining the target product, mostly existing as an organic-inorganic complex or a mixture of solids, and some also existing in sol form. In the embodiments of this application, the precursor of the fiber composite board is a form existing before the fiber composite board is prepared and formed. The precursor of the fiber composite board will be different depending on the material of the fiber composite board or the ratio of the materials.

[0063] This type of back cover, which combines a metal substrate with a fiber composite board in a single structural layer, can further reduce the overall thickness of the bottleneck area while ensuring the rigidity of the metal substrate is met. The thickness of the second region can be flexibly set according to the height of the adapted mid-frame, main board, and sub-board.

[0064] For example, refer to Figure 6 The schematic diagram of the back cover structure of the electronic device is shown below. Figure 6 The back cover of the electronic device is shown in a YZ cross-sectional view. The back cover has a dual-layer structure, comprising a first layer and a second layer of unequal thickness. Taking the first layer, mainly composed of a first fiber composite board 6031, a metal substrate 6032, and a second fiber composite board 6033, as the inner layer of the back cover, and the second layer, a veneer 6036, as the outer layer, as an example, this will be explained. The first layer and the veneer 6036 can be bonded together using an adhesive layer 6037 or double-sided adhesive. After the back cover is placed in the electronic device's frame 602, the orthographic projection of the first fiber composite board 6031 in the X direction includes the orthographic projection of the motherboard 604 in the Z direction; the orthographic projection of the metal substrate 6032 in the Z direction includes the orthographic projection of the battery 605 in the Z direction; and the orthographic projection of the second fiber composite board 6033 in the Z direction includes the orthographic projection of the sub-board 606 in the Z direction. The region corresponding to the metal substrate 6032 is a thickness bottleneck region, while the regions corresponding to the first fiber composite plate 6031 and the second fiber composite plate 6033 are non-thickness bottleneck regions. The thickness of the metal substrate 6032 is less than the thickness of the first fiber composite plate 6031 and the second fiber composite plate 6033.

[0065] The metal substrate can include, but is not limited to, stainless steel substrates, aluminum alloy substrates, etc. In an optional embodiment, the thickness of the metal substrate is set to 0.15mm to 0.3mm. Setting the thickness of the metal substrate to 0.15mm to 0.3mm, while ensuring the rigidity of the metal substrate 6032 meets the requirements, can further reduce the overall thickness of the thickness bottleneck area. The vegan leather 6036 used as the back cover covering layer can also be replaced with materials such as polyurethane (PU), genuine leather, and bamboo veneer. This optional method of splicing the first structural layer of the fiber composite board and the metal substrate with the vegan leather composite structure can improve both the aesthetics and the grip feel of the electronic device's back cover.

[0066] For example, continue to refer to Figure 6The overlapping areas of the metal substrate 6032 and the first fiber composite board 6031 are bonded and fixed by a first double-sided adhesive 6034, and the overlapping areas of the metal substrate 6032 and the second fiber composite board 6031 are bonded and fixed by a second double-sided adhesive 6035. In an optional embodiment, the bonding width of the first double-sided adhesive 6034 and the second double-sided adhesive 6035 is 0.7 to 3.5 mm, for example, the bonding width is the length along the Y-axis, and the adhesive layer thickness is 0.05 to 0.3 mm. When bonding the first fiber composite board 5031, the metal substrate 5032, and the second fiber composite board 6033 with adhesives, the bonding width can also be controlled to be 0.7 to 3.5 mm, and the adhesive layer thickness to be 0.05 to 0.3 mm. By controlling the bonding width and adhesive layer thickness within the above optional ranges, the influence of the adhesive layer thickness on the overall thickness of the electronic device can be minimized while ensuring bonding stability.

[0067] In addition to the above Figures 3 to 6 In addition to the structure shown that reduces the thickness of the bottleneck area in the back cover, to achieve a fit between the fiber composite back cover and the glass back cover with the same electronic device frame, the thickness of the fiber composite board in the adhesive area can be gradually reduced, ultimately resulting in a back cover with a progressively thinner thickness from the center to the edge. The adhesive area of ​​the fiber composite board is the first area of ​​the unequal-thickness fiber composite board. For example, as... Figure 7 The schematic diagram of the back cover structure of the electronic device is shown in the figure. Figure 7 The back cover of the electronic device is shown in the XZ cross-sectional diagram. The back cover is a composite layer structure of fiber composite board 7031 and vegan leather 7032, which are bonded and fixed by adhesive layer 7033. Optionally, adhesive layer 7033 can also be replaced with double-sided tape.

[0068] After the back cover is placed within the electronic device's frame 702, the fiber composite board 7031 is fixedly bonded to the frame 702 using double-sided adhesive 7034. The thickness of the adhesive area on the fiber composite board 7031 gradually changes, increasing from the edge of the back cover towards the center; that is, the adhesive area is thicker the further away from the outer edge of the frame. The vegan leather 7032 has a uniform thickness. The frame is a thick frame; its inner edge is fitted and fixed to the back cover and display screen, while its outer edge is exposed outside the device. It should be noted that the vegan leather 7032 can also be made with a textured surface, making the back cover more personalized and aesthetically pleasing. Figure 8 This is a schematic diagram showing the gradual change in thickness of the fiber composite board, as shown below. Figure 8As shown, the thickness of the fiber composite board is positively correlated with the distance between the outer edge of the frame and the outer edge. A smaller distance results in a thinner board, and a larger distance results in a thicker board. The effect is that the outer edge of the fiber composite board is thinner, while the inner edge is thicker. The maximum thickness at the center of the fiber composite board can be set by those skilled in the art according to actual needs. The thicker the center of the fiber composite board, the greater the height difference between the edge and the center of the back cover, and the more pronounced the bulge at the center of the back cover. The thickness of the outermost edge of the fiber composite board is 0.15–0.45 mm. Setting the thickness of the outermost edge of the fiber composite board to 0.15–0.45 mm allows the back cover of this embodiment to be adapted to the same electronic device frame as the glass back cover.

[0069] This application also provides a back cover with a composite layer structure of an unequal-thickness fiber composite board and an unequal-thickness veneer. The back cover has a veneer covering the outer surface of the unequal-thickness fiber composite board; after partial hot stamping of the veneer, the veneer exhibits an unequal-thickness shape. Exemplarily, the hot stamping process of the back cover in this embodiment is as follows: Figures 9a-9b The schematic diagram shows the partial hot stamping process of the vegan leather. Figures 9a-9b The back cover of the electronic device in the diagram is shown in an XZ cross-sectional view. For example... Figure 9a As shown, the back cover is a composite layer structure of fiber composite board 9031 of unequal thickness and plain leather 9032. The fiber composite board 9031 and plain leather 9032 are bonded and fixed together by adhesive layer 9033. The fiber composite board 9031 is fixed and bonded to the middle frame 902 by double-sided adhesive 9034. For the relevant explanation of the thickness gradient of the fiber composite board 9031 of unequal thickness, please refer to... Figure 7 The relevant descriptions in the illustrated embodiments are sufficient. When preparing unequal-thickness veneer, the hot stamping mold 901 is placed above the area to be stamped on the veneer 9032. A schematic diagram of the back cover structure after hot stamping is shown below. Figure 9b As shown, after hot stamping with a hot stamping mold, the thickness of the unequal-thickness fiber composite board 9031 remains unchanged, while the localized area of ​​the vegan leather 9032 after hot stamping is designated as the third region, which can also be referred to as the thickness reduction of the hot stamping area. The third region is located at a predetermined distance from the outer edge of the middle frame. The specific value of the predetermined distance can be set by those skilled in the art according to actual needs, for example, the third region can be located in the middle part of the outer surface of the vegan leather, or the third region can be located on the outer surface of the vegan leather near the outer edge of the middle frame. For example, the area of ​​the vegan leather 9032 after hot stamping with the hot stamping mold is the third region, and the vegan leather in the third region becomes thicker the farther it is from the outer edge of the middle frame. The vegan leather 9032 serves as the covering layer of the back cover, and the vegan leather 9032 can also be replaced with materials such as polyurethane (PU), genuine leather, or bamboo veneer. Figure 9b As shown, a protrusion 9035 is provided in the first structural layer near the outer edge of the middle frame, wherein the protrusion 9035 is... Figure 9bThe area enclosed by the dashed line shows a smooth transition between the raised upper surface and the embossed upper surface of the third area of ​​the cover layer. The size of the raised surface can be flexibly set according to the thickness of the vegan leather layer. Protrusions at the edge of the first structural layer can engage the embossed cover layer, improving the adhesion between the cover layer and the first structural layer. Furthermore, the smooth transition between the raised upper surface and the embossed upper surface of the third area of ​​the cover layer enhances the smoothness of the outer surface of the back cover.

[0070] In this optional embodiment, the vegan leather is prepared into an uneven thickness structure by hot stamping with a mold, and the vegan leather at the outer edge of the back cover is thinned, so that the thickness at the edge of the back cover is reduced, and it is better adapted to the electronic device frame with the glass back cover.

[0071] In addition to thinning the edge portion of the back cover leather as shown in Figure 9, the entire back cover leather can also be thinned. For example, Figures 10a-10c This is a schematic diagram of the overall hot stamping process for vegan leather. Figures 10a-10c This is a schematic diagram of the XZ cross-section of the back cover, where, Figure 10a This is a schematic diagram of the back cover structure before hot stamping. The back cover is a composite layer structure of a fiber composite board 10031 of unequal thickness and a vegan leather 10032. The fiber composite board 10031 and the vegan leather 10032 are bonded and fixed by an adhesive layer 10033. The fiber composite board 10031 is fixed and bonded to the middle frame 1002 by a first double-sided adhesive 10034 and a second double-sided adhesive 10035. The thickness of the fiber composite board 10031 of unequal thickness gradually increases from the edges of the two middle frames 1002 to the left and right edges of the battery 1005. The area of ​​the fiber composite board 10031 of unequal thickness opposite to the battery has the same thickness. The vegan leather 10032 covers the outer surface of the fiber composite board 10031 of unequal thickness with equal thickness. Figure 10b As shown, the entire vegan leather 10032 serves as the area to be hot-stamped. After the hot-stamping mold 1006 is placed over the vegan leather 10032, the entire vegan leather 10032 is hot-stamped. The schematic diagram of the back cover structure after hot stamping is shown below. Figure 10c As shown, vegan skin 10032 compared to Figure 10a The vegan skin 10032 is thinned overall. For example... Figure 10c As shown, a protrusion 10036 is provided near the outer edge of the middle frame in the first structural layer. The protrusion 10036 is... Figure 10c The portion circled in dashed lines. The raised upper surface 10036 smoothly transitions to the upper surface of the embossed cover layer. The raised surface at the edge of the first structural layer can engage the embossed cover layer, improving the adhesion between the cover layer and the first structural layer. The smooth transition between the raised upper surface and the overall embossed upper surface of the cover layer enhances the smoothness of the outer surface of the back cover.

[0072] The vegan leather 10032 serves as the back cover layer. It can also be replaced with polyurethane (PU), genuine leather, or bamboo veneer. Pre-set graphics can be hot-stamped onto the vegan leather 10032 using a hot stamping mold.

[0073] This optional hot stamping method for the entire vegan leather surface of the back cover can not only reduce the thickness of the back cover edges, but also reduce the overall thickness of the back cover, thereby reducing the overall thickness of the electronic device. Hot stamping of vegan leather can also be applied to 2D back covers; by hot stamping a portion of the vegan leather surface of a 2D back cover, a 2.5D effect can be achieved.

[0074] For example, Figures 11a-11b This is a schematic diagram of the hot stamping process for the 2D back cover. Figures 11a-11b This is a schematic diagram of the XZ cross-section of the back cover. Specifically, Figure 11a This is a schematic diagram showing the positional relationship between the 2D back cover and the hot stamping mold. Figure 11b This is a schematic diagram of the 2.5D back cover structure after hot stamping. (For example...) Figure 11a As shown, the 2D back cover includes a fiber composite board 11031 and a vegan leather 11032. The fiber composite board 11031 is bonded to the vegan leather 11032 via an adhesive layer 11033. When the 2D back cover is placed in the middle frame 1102, the fiber composite board 11031 is fixedly bonded to the middle frame 1102 via double-sided adhesive 11034. A hot stamping mold 1104 is placed on the edge area of ​​the vegan leather near the middle frame 1102 for hot stamping. The area of ​​the vegan leather 11032 edge after being hot stamped by the hot stamping mold is the third area. A schematic diagram of the back cover structure after hot stamping is shown below. Figure 11b As shown, the thickness of the third area of ​​the vegan leather gradually changes, becoming thinner as it gets closer to the edge of the mid-frame. The edges of the vegan leather 11032 on the 2D back cover are rounded, presenting a 2.5D effect. It should be noted that the hot stamping tool can also stamp preset graphics, such as personalized graphics or mobile phone brand logos, onto the area to be stamped on the vegan leather 11032.

[0075] This method of hot stamping the edges of the vegan leather back cover to achieve a 2.5D back cover effect is beneficial for creating a better back cover shape and can also reduce the scratchy feel of the back cover.

[0076] It should be noted that, in addition to providing a covering layer such as genuine leather, bamboo veneer, or plain leather on the outer surface of the first structural layer, a decorative layer or ceramic layer can also be provided. The decorative layer includes a coating, which is a solid continuous film obtained by applying paint, providing protective, insulating, and decorative effects. The coating material can be, but is not limited to, chromium nitride, titanium nitride, titanium carbonitride, titanium carbide, and tungsten carbide carbon film. The decorative layer serves a decorative purpose on the back cover of electronic devices.

[0077] The following description continues, using a fiber composite board as the first structural layer as an example, to illustrate the back cover with a composite structure of the first structural layer and the ceramic layer. The adhesive surface between a single ceramic back cover and the electronic device frame requires precise control of its shape to achieve good adhesion and sealing. Therefore, the CNC machining of a single ceramic back cover requires high precision but is time-consuming. In this embodiment, a fiber composite board is bonded to the inner surface of the ceramic to prepare the back cover, thus solving the problems of high CNC machining precision and long machining time associated with single ceramic back covers.

[0078] For example, such as Figure 12 The schematic diagram of the ceramic back cover structure of the electronic device is shown below. Figure 12 The diagram shows the XZ cross-section of the back cover. The ceramic back cover includes a fiber composite board 12031 and a ceramic layer 12032. The fiber composite board 12031 is bonded to the electronic device frame 1202 using double-sided adhesive 12033. The bonding process of the fiber composite board 12031 and the ceramic layer 12032 can be as follows: The precursor of the fiber composite board 12031 is hot-pressed using a pre-set mold to prepare a shaped bonding surface; then, the bonding surface is bonded to the inside of the ceramic layer 12032, completing the bonding. This method of bonding the fiber composite board to the ceramic layer requires lower processing precision for the ceramic layer bonding surface, saving time and labor costs associated with CNC machining of the ceramic layer bonding surface. After preparing the shaped bonding surface, the fiber composite board 12031 can be directly hot-pressed onto the inner surface of the ceramic layer 12032, achieving bonding through molecular forces between the fiber composite board and the ceramic interface. In addition, the molded bonding surface of the fiber composite board 12301 can also be bonded to the inner surface of the ceramic layer 12302 by adhesive or double-sided adhesive.

[0079] The precursor is a resin matrix impregnated with continuous fibers or fabric under strictly controlled conditions to form a composition of resin matrix and reinforcement, such as fiber-reinforced resin. Hot pressing involves pressing the prepared composition into a pre-designed mold at a preset temperature to obtain a shaped fiber composite board. Finally, the pressed fiber composite board is cured to obtain the final desired fiber composite board. The preset temperature and the shape of the preset mold during hot pressing can be flexibly set by those skilled in the art according to actual needs, and no specific limitations are made in this embodiment.

[0080] like Figure 12As shown, a fiber composite board 12301 is entirely covered on the inner surface of the ceramic layer 12032. The fiber composite board 12301 covering the inner surface of the ceramic layer 12032 has an uneven thickness. The thickness of the first region of the fiber composite board 12301 is greater than the thickness of the second region. The first region is the area where the fiber composite board is bonded and fixed to the frame of the electronic device. The second region is the area of ​​the fiber composite board excluding the first region. The fiber composite board 12301 is thinner in the middle and thicker at the edges. Since the reliability weaknesses of a single ceramic back cover are at the four corners, by covering the inside of the single ceramic layer with a fiber composite board that is thinner in the middle and thicker at the edges, the rigidity of the four corners of the ceramic back cover can be enhanced, thereby improving the overall reliability of the ceramic back cover.

[0081] For example, such as Figure 13 The schematic diagram of the ceramic back cover structure of the electronic device is shown below. Figure 13 The diagram shows an XZ cross-section of the ceramic back cover, which includes a fiber composite board 13031 and a ceramic layer 13032. The fiber composite board 13031 is bonded to the electronic device frame 1302 using double-sided adhesive 13033. The inner surface of the ceramic layer 13032 is not entirely covered with the fiber composite board; instead, a hollow fiber composite board 13301 is attached to the edge of the inner surface of the ceramic layer 13032. The size and shape of the hollow fiber composite board can be set by those skilled in the art according to actual needs.

[0082] Since the weakest points in the reliability of a single ceramic back cover are at the four corners, attaching annular fiber composite plates to the inner edges of the single ceramic layer can improve the corner stiffness of the ceramic back cover, thereby enhancing the overall reliability of the ceramic back cover. The thickness of the ceramic back cover and the annular fiber composite plate can be set by those skilled in the art according to actual needs. Furthermore, the annular fiber composite plate can also be fabricated with unequal thickness structures; for example, the closer the distance to the frame, the thicker the fiber composite plate. Moreover, the fiber composite plate can also be attached only to the four corners of the ceramic layer.

[0083] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A back cover of an electronic device, characterized by, include: A first structural layer and a second structural layer, wherein the first structural layer is made of fiber-reinforced resin, and the fiber-reinforced resin is a composition of continuous fibers and resin; The second structural layer is located on the outer surface of the first structural layer, and the second structural layer and the first structural layer are bonded and fixed together by an adhesive layer; the second structural layer includes a third region, which is a partial area of ​​the second structural layer after hot stamping by the hot stamping mold; The first structural layer includes a first region and a second region, the thickness of the first region being greater than the thickness of the second region, wherein, along the thickness direction of the electronic device, the second region forms a second region orthographic projection, the battery of the electronic device forms a battery orthographic projection, and the second region orthographic projection includes the battery orthographic projection; The first structural layer further includes a protrusion disposed on the outer edge of the first structural layer near the middle frame of the electronic device, and the upper surface of the protrusion smoothly transitions to the upper surface of the third region after embossing.

2. The back cover of claim 1, wherein, The first area is the area that is bonded and fixed to the middle frame.

3. The back cover of claim 2, wherein, The thickness of the first region gradually changes, wherein the thickness of the first region increases the further away from the outer edge of the middle frame.

4. The back cover of claim 3, wherein, The thickness of the outer edge of the first region ranges from 0.15 mm to 0.45 mm.

5. The back cover of claim 1, wherein, The thickness of the third region gradually changes, wherein the thickness of the third region increases the further away from the outer edge of the middle frame.

6. The back cover of claim 1, wherein, The second structural layer is hot-stamped using a hot stamping mold.

7. The back cover of claim 6, wherein, The second structural layer has a uniform thickness.

8. The back cover of claim 6, wherein, The upper surface of the protrusion smoothly transitions to the upper surface of the second structure after lamination.

9. The back cover of claim 1, wherein: The material of the second structural layer is vegan leather, genuine leather, or bamboo veneer.

10. The back cover of claim 1, wherein, The second structural layer is a ceramic layer.

11. The back cover of claim 10, wherein, The first structural layer is bonded to the inner surface of the ceramic layer by a hot pressing process.

12. The back cover of claim 10, wherein, The first structural layer is bonded to the inner surface of the ceramic layer by an adhesive layer.

13. The back cover of claim 10, wherein, The thickness of the second region is 0.

14. The back cover of claim 1, wherein, The second structural layer is a decorative layer, which is a coating.

15. An electronic device, comprising: Includes a mid-frame, a display screen, and a back cover of the electronic device as described in any one of claims 1-14.

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