Rear cover, rear shell, rear cover assembly and electronic equipment

Abstract

The embodiment of the invention provides a rear cover, a rear shell, a rear cover assembly and electronic equipment, and belongs to the technical field of rear covers. The back cover includes a first metal layer and a second metal layer. Wherein the second metal layer is located on the inner side of the first metal layer in the thickness direction of the rear cover, and the second metal layer is of a porous structure. In this way, the rear cover with the metal texture is achieved, and meanwhile the problem that the metal rear cover is hot in hand feeling is solved.

Description

Technical Field

[0001] This application relates to the field of back cover technology, and in particular to a back cover, back shell, back cover assembly and electronic device. Background Technology

[0002] Currently, electronic devices such as mobile phones and tablets consist of a display screen, a mid-frame, and a back cover. The back cover and display screen are located on opposite sides of the mid-frame, forming a space that houses the functional components of the electronic device, such as the battery and camera module. In related technologies, aluminum alloy is used to make the metal back cover, achieving a metallic appearance. However, aluminum alloy has a high thermal conductivity, resulting in rapid heat transfer. During use, the metal back cover becomes very hot, causing a burning sensation and negatively impacting the user experience. Summary of the Invention

[0003] This application provides a back cover, a back shell, a back cover assembly, and an electronic device, achieving a back cover with a metallic texture while solving the problem of it feeling hot to the touch.

[0004] In a first aspect, embodiments of this application provide a back cover, which includes a first metal layer and a second metal layer. The second metal layer is located inside the first metal layer along the thickness direction of the back cover, and the second metal layer has a porous structure.

[0005] In this embodiment, the first metal layer is located outside the second metal layer, providing a metallic texture and giving the outer surface of the back cover a metallic appearance. The outer surface of the back cover is its exterior surface, thus giving it a metallic appearance. The second metal layer has a porous structure, reducing the heat transfer area and narrowing the heat transfer channels. This reduces heat transfer and heat storage, resulting in less heat being transferred from the second metal layer to the first metal layer, thus keeping the first metal layer at a lower temperature and preventing it from feeling hot to the touch, improving the user experience. Furthermore, the porous structure reduces the weight of the second metal layer, keeping the overall weight of the back cover within a lower range, contributing to a lightweight design. In addition, the porous structure increases the overall strength of the second metal layer, providing support and ensuring the overall strength of the back cover meets requirements, preventing cracking or deformation upon drop.

[0006] In some possible implementations, the thermal conductivity of the second metal layer is less than or equal to 50 W / (m·K), and / or the thermal diffusivity of the second metal layer is less than or equal to 5 × 10⁻⁶. -5 m 2 / s.

[0007] In this implementation, limiting the thermal conductivity and / or thermal diffusivity of the second metal layer means that the second metal layer is made of a low thermal conductivity metal material, which makes the second metal layer have low thermal conductivity, thereby further reducing the heat transferred to the first metal layer through the second metal layer, and further reducing the heat on the first metal layer, thus achieving a better temperature control effect.

[0008] In some possible implementations, the porous structure includes multiple sub-holes, each of which is a blind hole and located inside the second metal layer, which is the side of the second metal layer away from the first metal layer along the thickness direction of the back cover.

[0009] In this implementation, when all sub-holes are blind holes, the contact area between the second metal layer and the third metal layer or the first metal layer can be increased, which helps to improve the connection strength between the second metal layer and the first or third metal layer. Additionally, the fabrication process of the back cover can be optimized, reducing process steps and improving fabrication efficiency. Finally, the first and second metal layers can be joined together first, and then the second metal layer can be etched to form the sub-holes without etching through the second metal layer, thus protecting the first metal layer from damage.

[0010] In some possible implementations, the second metal layer includes a central region and an edge region. The sub-via is located inside the central region, and the edge region surrounds the central region.

[0011] In this implementation, the adhesive backing can be placed between the edge area of ​​the second metal layer and the middle frame to achieve bonding between the back cover and the middle frame. Furthermore, the sub-holes are located outside the edge area, resulting in a larger bonding area between the adhesive backing and the back cover. This does not reduce the bonding area between the back cover and the adhesive backing, thus ensuring the structural strength of the adhesive assembly between the middle frame and the back cover.

[0012] In some possible implementations, the width of the edge area is greater than or equal to 0.5 mm in the direction perpendicular to the thickness of the back cover.

[0013] This implementation ensures that the edge area has sufficient area to cooperate with the adhesive backing, thus ensuring the bonding strength between the back cover and the middle frame.

[0014] In some possible implementations, the width of the edge region is less than or equal to 3 mm.

[0015] In this implementation, the width of the edge region is controlled within a reasonable range, and the area of ​​the central region is increased. This allows for the setting of more sub-holes, which helps to further reduce the heat transfer channels of the second metal layer.

[0016] In some possible implementations, the second metal layer is made of a porous metal material. Porous metal materials are those containing a large number of pores (porosity typically >20%), and their structure consists of a metal matrix and pores. The pore morphology can be open (interconnected) or closed (independent and sealed). This porous structure reduces heat transfer and heat storage, minimizing heat transfer to the first metal layer and achieving good insulation, thus solving the problem of the material feeling hot to the touch. Furthermore, the low density of porous metal materials makes the second metal layer lightweight, reducing the weight of the back cover and enabling a lightweight back cover design.

[0017] In some possible implementations, the porous metal material is either a foamed metal material or a metal fiber felt.

[0018] In this way, the numerous pores in the foam metal material and metal fiber felt create a porous structure, reducing heat transfer channels in the second metal layer and achieving excellent thermal insulation. The high strength and elastic modulus of the foam metal material and metal fiber felt provide better support stiffness for the overall back cover structure. Due to the low density of the foam metal material and metal fiber felt, the second metal layer is lightweight, resulting in minimal increase in the overall weight of the back cover. Furthermore, readily available foam metal materials (such as foamed titanium) or metal fiber felt (such as titanium fiber felt) can be used as the material for the second metal layer, eliminating the need for etching pores on the second metal layer. This simplifies the fabrication of the porous structure, reduces the number of processing steps for the back cover, improves production efficiency, and lowers the cost.

[0019] In some possible implementations, the second metal layer is integrally formed, thus making it a one-piece structure, which can reduce the assembly steps of the back cover and improve the production efficiency of the second metal layer.

[0020] In some possible implementations, the second metal layer comprises at least two metal portions joined together, such that the orthographic projections of two adjacent metal portions onto the first metal layer do not at least partially overlap in a direction perpendicular to the thickness direction of the back cover.

[0021] In this way, the second metal layer is a split structure composed of multiple metal parts, which can be designed specifically according to the heat generation of different areas inside the electronic device and the strength requirements of different areas of the back cover, so as to further optimize the strength and / or heat insulation effect of the second metal layer.

[0022] In some possible implementations, adjacent metal parts are welded together in a direction perpendicular to the thickness of the back cover.

[0023] In this way, the connection strength between two adjacent metal parts is high, which improves the overall strength of the second metal layer.

[0024] In some possible implementations, at least two metal parts include a first metal part and a second metal part, with a porous structure disposed in the first metal part and the second metal part being a solid metal part.

[0025] In this way, by placing a second metal part in the area where strength support is required, the overall strength of the second metal layer is optimized while reducing heat transfer.

[0026] In some possible implementations, the first metal part and the second metal part are made of different materials.

[0027] In this way, by controlling the materials of the first metal part and the second metal part, different requirements can be met.

[0028] In some possible implementations, the first metal layer is directly connected to the second metal layer.

[0029] This reduces the number of layers that make up the back cover, thus reducing its thickness and helping to achieve a thinner and lighter design.

[0030] In some possible implementations, the first metal layer is welded to the second metal layer, which can be applied to scenarios where the connection strength requirement is not high, thus reducing costs.

[0031] In some possible implementations, the first and second metal layers are diffusion-bonded. Diffusion bonding is a joining technique between solid materials that achieves bonding by inducing the diffusion of atoms at the contact surfaces under high temperature and pressure. This technique does not use filler metals or other additives, but relies on the atomic movement of the materials themselves to form a strong joint. Due to atomic-level diffusion and bonding, the resulting joint strength approaches or can even reach the level of the base material. Therefore, using diffusion bonding to connect the first and second metal layers can be applied to scenarios requiring high connection strength, ensuring that the back cover does not delaminate during processing and use.

[0032] In some possible implementations, the back cover also includes a third metal layer located between the first and second metal layers. The first metal layer is fixedly connected to the second metal layer through the third metal layer, which can achieve better interlayer bonding and further improve the connection strength between the first and second metal layers.

[0033] In some possible implementations, the third metal layer is welded to the first metal layer, which can be applied to scenarios where the connection strength requirement is not high, thus reducing costs.

[0034] In some possible implementations, the third metal layer is diffused and bonded to the first metal layer, which can be applied to scenarios with high requirements for connection strength.

[0035] In some possible implementations, the third metal layer is welded to the second metal layer, which can be applied to scenarios where the connection strength requirement is not high, thus reducing costs.

[0036] In some possible implementations, the third metal layer is diffused and combined with the second metal layer, which can be applied to scenarios with high requirements for connection strength.

[0037] In some possible implementations, the first metal layer is a single-layer structure, or the first metal layer comprises multiple sub-metal layers arranged side-by-side along the thickness direction of the back cover, such that the first metal layer is a multi-layer structure.

[0038] In this way, the first metal layer can be a single-layer structure or a multi-layer structure to meet different usage requirements.

[0039] In some possible implementations, the first metal layer is made of aluminum alloy, titanium, or stainless steel, which can achieve a metallic back cover appearance.

[0040] In some possible implementations, the material of the second metal layer is titanium, iron-based metal, magnesium-based metal, or nickel-based alloy.

[0041] In this way, the second metal layer has low thermal conductivity, which can reduce heat transfer to the first metal layer and solve the problem of it feeling hot to the touch.

[0042] In some possible implementations, the back cover also includes a first through hole that extends through the back cover along its thickness direction.

[0043] In this way, it can work in conjunction with the camera module to ensure that the camera module can capture images of the outside world and take pictures.

[0044] In some possible implementations, the back cover also includes a second through-hole and a non-metallic component. The second through-hole extends through the back cover along its thickness. At least a portion of the non-metallic component is located inside the second through-hole.

[0045] In this way, the coil that enables wireless charging can be placed inside the second through hole. In the thickness direction of the electronic device, there are no metal objects between the transmitting coil and the receiving coil that enable wireless charging, which can improve the efficiency of wireless charging, improve safety, and protect the health of the electronic device.

[0046] In some possible implementations, the first metal layer includes a first portion and a second portion. The second metal layer is located inside the first portion, and its orthographic projection onto the first metal layer does not coincide with the second portion. A second through-hole penetrates the second portion along the thickness direction of the back cover, and is spaced apart from the second metal layer along an extension direction perpendicular to the centerline of the second through-hole.

[0047] In this way, the sidewall of the second through-hole is mainly composed of the first metal layer, avoiding the possibility of the second metal layer forming part of the sidewall. While ensuring high wireless charging efficiency, the second metal layer can be made of materials that significantly affect wireless charging, such as titanium. The impact of wireless charging mainly refers to the skin effect generated on the surface of the metal material due to the wireless charging frequency. The skin effect heats the metal. Based on the skin effect and heating mechanism, and considering the physical properties of different metal materials, for example, the heating effect of aluminum alloy is much lower than that of titanium alloy.

[0048] In some possible implementations, the back cover also includes a surface treatment layer located on the outer surface of the first metal layer.

[0049] This achieves a differentiated metallic appearance. Additionally, it improves the back cover's wear resistance and corrosion resistance.

[0050] In some possible implementations, the surface treatment layer includes an oxide layer located on the outer surface of the first metal layer.

[0051] In this way, the outer surface of the first metal layer is more wear-resistant and environmentally resistant, and achieves a differentiated appearance.

[0052] In some possible implementations, the back cover also includes a raised structure that is fixedly connected to the inner surface of the second metal layer.

[0053] In this way, by setting up protruding structures, functions such as assembly, limiting, positioning, and structural support can be achieved.

[0054] In some possible implementations, the back cover further includes a protective layer that covers the sidewalls of the first metal layer and the second metal layer. Alternatively, the back cover may also include a protective layer and an intermediate layer located between the first and second metal layers, the protective layer covering the sidewalls of the first metal layer, the second metal layer, and the intermediate layer.

[0055] In this way, by setting a protective layer, electrochemical corrosion of the metal layers of adjacent layers in the thickness direction of the back cover can be reduced.

[0056] Secondly, embodiments of this application provide a back cover, which includes a frame and a back cover as described in any of the first aspects, the frame surrounding the outer edge of the back cover, and the frame and the back cover being integrally formed.

[0057] In this way, the frame and back cover are molded as a single piece, forming the back shell of the Unibody architecture.

[0058] Thirdly, embodiments of this application provide a back cover assembly, which includes a camera decorative element and a back cover as described in any of the first aspects; or, the back cover assembly includes a camera decorative element and a rear shell as described in the second aspect, the rear shell including the back cover. The back cover has a first through hole, and the camera decorative element is disposed at the first through hole of the back cover and fixedly connected to the back cover.

[0059] Fourthly, embodiments of this application provide an electronic device, which includes a display screen, a mid-frame, and a back cover as described in any of the first aspects. The back cover and the display screen are located on opposite sides of the mid-frame, and are respectively connected to the mid-frame. The back cover, the display screen, and the mid-frame together form an accommodating space for accommodating components. The back cover includes a first metal layer and a second metal layer, and along the thickness direction of the back cover, the second metal layer is located between the outer surface of the first metal layer and the mid-frame.

[0060] Fifthly, embodiments of this application provide an electronic device, which includes a display screen and a rear housing as described in the second aspect. The rear housing is connected to the display screen to form an accommodating space for accommodating components. The rear housing includes a first metal layer and a second metal layer, with the second metal layer located between the outer surfaces of the display screen and the first metal layer along the thickness direction of the display screen. Attached Figure Description

[0061] Figure 1 A three-dimensional structural schematic diagram of an electronic device provided in an embodiment of this application;

[0062] Figure 2 for Figure 1 An exploded view of the electronic device shown.

[0063] Figure 3 for Figure 2 A three-dimensional cross-sectional view of the rear cover assembly;

[0064] Figure 4 for Figure 3 Enlarged view of point K;

[0065] Figure 5 This is a schematic diagram of a first three-dimensional structure of a rear shell provided in an embodiment of this application;

[0066] Figure 6 for Figure 5 A schematic diagram of the second three-dimensional structure of the rear shell shown;

[0067] Figure 7 for Figure 6 A schematic diagram at point P in the middle;

[0068] Figure 8 for Figure 2 A three-dimensional structural diagram of the back cover;

[0069] Figure 9 for Figure 8 Cross-sectional view along the BB direction;

[0070] Figure 10 for Figure 9 A schematic diagram at point M in the middle;

[0071] Figure 11 for Figure 8 A three-dimensional sectional view along the BB direction at point C;

[0072] Figure 12 for Figure 8 A schematic diagram at point D in the middle;

[0073] Figure 13 A cross-sectional schematic diagram of the second type of back cover provided in Embodiment 1 of this application;

[0074] Figure 14 A cross-sectional schematic diagram of the third type of back cover provided in Embodiment 1 of this application;

[0075] Figure 15 A cross-sectional structural diagram of the fourth type of back cover provided in Embodiment 1 of this application;

[0076] Figure 16 A three-dimensional structural diagram of the fifth type of back cover provided in Embodiment 1 of this application;

[0077] Figure 17 A three-dimensional structural diagram of the sixth type of back cover provided in Embodiment 1 of this application;

[0078] Figure 18 for Figure 17 A cross-sectional view along the EE direction;

[0079] Figure 19 for Figure 18 A schematic diagram at point R in the middle;

[0080] Figure 20 A three-dimensional structural diagram of the seventh type of back cover provided in Embodiment 1 of this application;

[0081] Figure 21 A cross-sectional schematic diagram of the eighth type of back cover provided in Embodiment 1 of this application;

[0082] Figure 22 A cross-sectional schematic diagram of the ninth type of back cover provided in Embodiment 1 of this application;

[0083] Figure 23 A cross-sectional schematic diagram of the tenth type of back cover provided in Embodiment 1 of this application;

[0084] Figure 24 This is a schematic diagram of step one of the methods for preparing a back cover assembly according to Embodiment 1 of this application;

[0085] Figure 25 This is a schematic diagram of step two in a method for preparing a back cover assembly according to Embodiment 1 of this application;

[0086] Figure 26 This is a schematic diagram of step one of the methods for preparing a back cover assembly according to Embodiment 2 of this application;

[0087] Figure 27 This is a schematic diagram of step two in a method for preparing a back cover assembly according to Embodiment 2 of this application;

[0088] Figure 28 A top view schematic diagram of the first type of back cover provided in Embodiment 3 of this application;

[0089] Figure 29 for Figure 28 A cross-sectional view along the AA direction;

[0090] Figure 30 This is a cross-sectional schematic diagram of the second type of back cover provided in Embodiment 3 of this application;

[0091] Figure 31 This is a cross-sectional schematic diagram of the third type of back cover provided in Embodiment 3 of this application.

[0092] Explanation of reference numerals in the attached figures:

[0093] 100. Electronic devices;

[0094] 110. Rear cover assembly;

[0095] 10. Back cover; 10a. Body part; 10b. Protrusion;

[0096] 11. First metal layer;

[0097] 111. Sub-metal layer; 112. First part; 113. Second part;

[0098] 12. Second metal layer;

[0099] 121. Central area; 122. Edge area; 123. First metal portion; 124. Second metal portion; 13. Third metal layer;

[0100] 14. Zi Kong;

[0101] 15. First through hole;

[0102] 16. Second through hole;

[0103] 17. Surface treatment layer;

[0104] 18. Raised structure;

[0105] 19. Fitting through hole; 191. First hole section; 192. Second hole section;

[0106] 20. Camera decorative part; 21. Main body; 22. Circular part;

[0107] 30. Protective layer;

[0108] 120. Mid-frame; 12a. Metal mid-plate; 12b. Frame;

[0109] 130. Display screen;

[0110] 140. Back cover. Detailed Implementation

[0111] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0112] This application provides an electronic device 100, including but not limited to mobile phones, tablets, laptops, ultra-mobile personal computers (UMPCs), handheld computers, walkie-talkies, netbooks, POS machines, personal digital assistants (PDAs), wearable devices, virtual reality devices, Bluetooth speakers, in-vehicle devices, and other devices.

[0113] In this embodiment of the application, a mobile phone is used as an example of the above-mentioned electronic device 100 to specifically describe the structure of the electronic device 100.

[0114] Figure 1 This is a three-dimensional structural diagram of an electronic device provided in an embodiment of this application. Figure 2 for Figure 1 The diagram shows an exploded view of the electronic device. Figure 3 for Figure 2 A three-dimensional cross-sectional view of the rear cover assembly. Figure 4 for Figure 3 A magnified view of point K in the middle.

[0115] It should be noted that in the figures of the embodiments of this application, the X-axis can be defined as the length direction of the electronic device 100, the Y-axis as the width direction of the electronic device 100, and the Z-axis as the thickness direction of the electronic device 100.

[0116] In some embodiments, reference Figure 1 and Figure 2As shown, the electronic device 100 may include a mid-frame 120, a display screen 130, and a back cover 10. For example... Figure 3 As shown, the back cover assembly 110 includes a back cover 10 and a camera trim 20; the back cover 10 can also be referred to as a battery cover. Along the thickness direction of the electronic device 100 (e.g., ... Figure 2 (Z-direction), the display screen 130 and the back cover 10 are located on opposite sides of the middle frame 120. The display screen 130, the middle frame 120 and the back cover 10 can together form an accommodating space for accommodating components such as the motherboard, battery, and camera module.

[0117] It is understood that the thickness direction of the display screen 130, the thickness direction of the middle frame 120, and the thickness direction of the back cover 10 are the same as the thickness direction of the electronic device 100. The length direction of the display screen 130, the length direction of the middle frame 120, and the length direction of the back cover 10 are all the same as the length direction of the electronic device 100. The width direction of the display screen 130, the width direction of the middle frame 120, and the width direction of the back cover 10 are all the same as the width direction of the electronic device 100.

[0118] In some embodiments, the display screen 130 can be mounted on one side of the middle frame 120 in the thickness direction by adhesive bonding.

[0119] In some embodiments, the middle frame 120 and the back cover 10 can be formed separately and fixedly connected by welding, snap-fitting, bonding or other methods.

[0120] The middle frame 120 primarily serves to support the entire machine and can be made of materials such as metal, ceramic, glass, or plastic. The middle frame 120 may include a metal middle plate 12a and a frame 12b, with the frame 12b surrounding the outer perimeter of the metal middle plate 12a. Generally, the frame 12b may include a top frame, a bottom frame, a left frame, and a right frame, forming a square ring structure.

[0121] The frame 12b can be a metal frame, a ceramic frame, or a glass frame. When the frame 12b is a metal frame, the material of the metal frame includes, but is not limited to, aluminum alloy, stainless steel, steel-aluminum composite die-cast plate, or titanium alloy.

[0122] The materials of the metal plate 12a include, but are not limited to, aluminum plate, aluminum alloy, stainless steel, steel-aluminum composite die-cast plate, titanium alloy or magnesium alloy.

[0123] The metal middle plate 12a and the frame 12b can be snapped together, welded, glued or integrally formed, or the metal middle plate 12a and the frame 12b can be fixedly connected by injection molding.

[0124] Combination Figure 3 and Figure 4 As can be seen, the back cover 10 has a first through hole 15, which extends through the back cover 10 along its thickness direction. The first through hole 15 is used for inserting the camera module of the electronic device 100, allowing the camera module to be exposed to the external environment of the back cover 10 and to capture images of the surroundings, thereby enabling image capture. A camera decorative piece 20 is disposed at the first through hole 15 of the back cover 10 and is fixedly connected to the back cover 10. The camera decorative piece 20 serves to decorate the camera module and enhance the overall aesthetics of the electronic device 100.

[0125] The specific shape of the first through hole 15 is not limited here. For example, the first through hole 15 can be a round hole, or it can be other shapes, such as a triangular hole.

[0126] In some embodiments, combined with Figure 3 and Figure 4 It is known that the back cover 10 includes a body portion 10a and a protrusion 10b disposed on the outer surface of the body portion 10a. The first through hole 15 penetrates the body portion 10a and the protrusion 10b along the thickness direction of the back cover 10. The protrusion 10b has a mating through hole 19. The mating through hole 19 includes a first hole segment 191 and a second hole segment 192 whose center lines coincide. The first hole segment 191 is located between the inner surface of the body portion 10a and the second hole segment 192. The diameter of the first hole segment 191 is smaller than the diameter of the second hole segment 192. The first hole segment 191 and the second hole segment 192 form a step, which is used to support the camera decorative piece 20.

[0127] In some embodiments, such as Figure 4 As shown, the camera decoration 20 includes a main body 21 and an annular portion 22 disposed around the edge of the main body 21. The annular portion 22 and the main body 21 make the structure of the camera decoration 20 resemble a cylindrical structure. At least a portion of the annular portion 22 is located inside the mating through hole 19, and one end of the annular portion 22 away from the main body 21 is used to contact the step.

[0128] In some embodiments, the camera trim 20 is bonded to the protrusion 10b by adhesive bonding. Exemplarily, a gap for accommodating adhesive is provided between the sidewall of the annular portion 22 and the inner wall of the mating through hole 19.

[0129] Figure 5 This is a schematic diagram of a first three-dimensional structure of a rear shell provided in an embodiment of this application. Figure 6 for Figure 5 The diagram shows the second three-dimensional structure of the rear shell. Figure 7 for Figure 6 A schematic diagram at point P in the middle.

[0130] The back cover 140 has a unibody architecture. The back cover 10 can be integrally formed with the frame 12b through a secondary connection method, such as nano-injection molding, welding, or adhesive bonding.

[0131] For example, such as Figure 7 As shown, there is a gap between the frame 12b and the back cover 10. This gap is used to connect the frame 12b and the back cover 10. For example, the gap serves as a nano-injection seam to accommodate the injection molded body formed by nano-injection. The frame 12b forms an integral structure with the back cover 10 through the injection molded body located in the gap.

[0132] It should be noted that when the electronic device uses a back cover 140, the back cover 140 and the display screen 130 form a accommodating space for the components. At this time, the electronic device may also include a front cover assembly located in the accommodating space. The front cover assembly may also be called a middle board assembly. The front cover assembly and the back cover 10 of the back cover 140 have space in the thickness direction of the electronic device to accommodate components such as batteries and motherboards.

[0133] In one related technology, the back cover 10 is constructed from non-metallic materials such as glass, ceramic, or composite fiberboard. However, glass and ceramic materials are relatively brittle, and the back cover 10 made of glass or ceramic is prone to breakage upon drop. Composite fiberboard lacks strength, and the back cover 10 made of composite fiberboard is easily deformed. Furthermore, glass, ceramic, or composite fiberboard cannot achieve a high-gloss, differentiated metallic appearance, affecting the user experience.

[0134] In another related technology, the back cover 10 is made of metal to achieve a metallic appearance. Metal materials are also strong and will not crack or deform upon drop. However, metal materials have high thermal conductivity and wide heat transfer channels, resulting in rapid heat conduction. This makes it easy for the heat generated during the use of the electronic device 100 to be transferred to the outer surface of the back cover 10, causing a high surface temperature and a hot feel, thus affecting the user experience.

[0135] Therefore, how to achieve a metallic appearance for the back cover 10 while simultaneously addressing the issue of it getting hot to the touch has become an urgent problem to be solved.

[0136] In view of this, this application provides a back cover 10, which is composed of at least two metal layers. The outer metal layer is used to achieve a metallic appearance, and the inner metal layer is made of a metal material with a porous structure. The porous structure reduces the heat transfer channels and heat transfer area of ​​the inner metal layer, thereby slowing down the heat transfer to the outer metal layer. Consequently, less heat is on the outer metal layer, keeping its temperature within a lower range and preventing the outer surface of the back cover 10 from becoming too hot to the touch. Furthermore, the porous inner metal layer has high strength, providing support and ensuring that the overall strength of the back cover 10 meets reliability requirements such as strength and drop resistance. In addition, the lightweight nature of the porous metal material makes the inner metal layer lighter, reducing the overall weight of the back cover 10 and contributing to a lightweight design.

[0137] It should be noted that, in the following embodiments, the term "outer side" used to describe the various parts within the back cover 10 refers to the side of the object being described that faces away from the internal accommodating space of the electronic device 100; "outer surface" refers to the surface of the object being described that faces away from the internal accommodating space of the electronic device 100; "inner side" refers to the side of the object being described that faces the internal accommodating space of the electronic device 100; and "inner surface" refers to the surface of the object being described that faces the internal accommodating space of the electronic device 100. The thickness direction of the back cover 10 is the same as the thickness direction of the back cover assembly 110.

[0138] The back cover 10 provided in this application embodiment will be described in detail below with reference to specific embodiments.

[0139] Example 1

[0140] Figure 8 for Figure 2 A three-dimensional structural diagram of the back cover. Figure 9 for Figure 8 A cross-sectional view along the BB direction. Figure 10 for Figure 9 A schematic diagram at point M in the middle. Figure 11 for Figure 8 A three-dimensional sectional view of point C along the BB direction.

[0141] In this embodiment of the application, the back cover 10 includes components along the thickness direction of the back cover 10 (e.g., ...). Figure 10 Multiple metal layers stacked in the Z direction (e.g.) Figure 10 As shown, the back cover 10 includes two metal layers, namely a first metal layer 11 and a second metal layer 12. Of course, the back cover 10 can have more than two metal layers. The second metal layer 12 is along the thickness direction of the back cover 10 (e.g., ...). Figure 10The Z-direction) is located inside the first metal layer 11. As mentioned above, the back cover 10 also has a first through hole 15. In this case, the back cover 10 is formed by the first metal layer 11 and the second metal layer 12. Therefore, the first through hole 15 penetrates the first metal layer 11 and the second metal layer 12 along the thickness direction of the back cover 10.

[0142] After the electronic device 100 is assembled, the first metal layer 11 is located outside the second metal layer 12, and the first metal layer 11 is closer to the outside of the electronic device 100 than the second metal layer 12. Therefore, the first metal layer 11 provides a metallic texture, so that the outer surface of the back cover 10 has a metallic appearance. The outer surface of the back cover 10 is the appearance surface of the back cover 10, thus giving the appearance surface of the back cover 10 a metallic appearance.

[0143] The second metal layer 12 has a porous structure, which reduces the heat transfer area and narrows the heat transfer channel. This reduces heat transfer and heat storage, resulting in less heat being transferred to the first metal layer 11 through the second metal layer 12. Consequently, the temperature of the first metal layer 11 remains low, preventing it from feeling hot to the touch and improving the user experience.

[0144] Understandably, for the same volume, compared to a solid second metal layer 12, the porous structure reduces the solid volume of the second metal layer 12, thus reducing the volume of heat storage in the second metal layer 12 and consequently reducing heat storage.

[0145] It is understandable that the second metal layer 12 can be understood as a heat insulation structure or heat insulation layer, which isolates the heat between the first metal layer 11 and the inside of the electronic device 100, so that less or even no heat is transferred to the inside of the electronic device 100 of the first metal layer 11, thereby controlling the temperature of the first metal layer 11 within a suitable range, so that the user will not feel hot when holding the back cover 10, thus improving the user experience.

[0146] Furthermore, by incorporating a porous structure, the weight of the second metal layer 12 can be reduced, allowing the overall weight of the back cover 10 to be kept within a lower range, thus contributing to a lightweight design. In addition, the porous structure ensures high overall strength of the second metal layer 12, providing support and ensuring that the overall strength of the back cover 10 meets requirements, preventing cracking or deformation upon drop.

[0147] The processing methods for the first metal layer can include integral molding, CNC machining, etc. CNC machining, in Chinese, stands for Computer Numerical Control Machining, or simply Numerical Control Machining.

[0148] The material of the first metal layer 11 can be aluminum alloy, titanium, or stainless steel, etc. For example, in this embodiment, the material of the first metal layer 11 is aluminum alloy. In this case, the outer surface of the first metal layer 11 can be treated using a commonly used anodizing surface treatment process, which can reduce costs.

[0149] The thickness of the first metal layer 11 is not limited here. In one embodiment, the thickness of the first metal layer 11 along the thickness direction of the back cover 10 can be less than or equal to 0.35 mm, making the first metal layer 11 thinner, reducing the impact of the first metal layer 11 on the thickness of the back cover 10, and helping the back cover 10 to achieve a thinner and lighter design.

[0150] Of course, in some scenarios, the thickness of the first metal layer 11 can be greater than 0.35 mm, except for being less than or equal to 0.35 mm.

[0151] In some embodiments, such as Figure 11 As shown, the second metal layer 12 is integrally formed, thus the second metal layer 12 is an integral structure, which can reduce the assembly steps of the back cover 10 and improve the production efficiency of the second metal layer 12.

[0152] In this first embodiment, the material of the second metal layer 12 is a solid metal material, which refers to a metal material with a dense internal structure and extremely low porosity (typically <1%). Its atoms or grains are closely arranged, with almost no macroscopic or microscopic pores, exhibiting a uniform and continuous solid metal morphology. In other words, solid metal material also refers to traditional dense metals, the kind of metal material without pores.

[0153] The material of the second metal layer 12 can be a solid metal material such as titanium, iron-based metal, magnesium-based metal, or nickel-based alloy. For example, in this embodiment, the material of the second metal layer 12 is titanium. Titanium has high strength and elastic modulus, which can provide better support rigidity for the overall structure of the back cover 10.

[0154] In some possible implementations, the thermal conductivity of the second metal layer 12 is less than or equal to 50 W / (m·K), and / or the thermal diffusivity of the second metal layer 12 is less than or equal to 5 × 10⁻⁶. -5 m 2 / s.

[0155] Thus, by limiting the thermal conductivity and / or thermal diffusivity of the second metal layer 12, it means that the second metal layer 12 is made of a low thermal conductivity metal material, which makes the second metal layer 12 have low thermal conductivity, thereby further reducing the heat transferred to the first metal layer 11 through the second metal layer 12, and further reducing the heat on the first metal layer 11, achieving a better temperature control effect.

[0156] In some embodiments, the thermal conductivity of the second metal layer 12 is less than or equal to 50 W / (m·K). In other embodiments, the thermal diffusivity of the second metal layer 12 is less than or equal to 5*10⁻⁶. -5 m 2 / s. In some other embodiments, the thermal conductivity of the second metal layer 12 is less than or equal to 50 W / (m·K), and the thermal diffusivity of the second metal layer 12 is less than or equal to 5*10 - 5 m 2 / s.

[0157] It should be noted that the thermal conductivity of the second metal layer 12 was measured at room temperature (25±2℃), that is, the thermal conductivity of the second metal layer 12 at room temperature is less than or equal to 50W / (m·K).

[0158] It should also be noted that the test methods for thermal diffusivity and thermal conductivity can refer to GB / T 22588-2008 "Measuring Thermal Diffusivity or Thermal Conductivity by Flash Method".

[0159] There are no restrictions on the thermal conductivity of the second metal layer 12. For example, the thermal conductivity of the second metal layer 12 can be 6.7 W / (m·K), 20 W / (m·K), 30 W / (m·K), 40 W / (m·K), etc.

[0160] There are no restrictions on the thermal diffusivity of the second metal layer 12. For example, the thermal diffusivity of the second metal layer 12 could be 5*10. -5 m 2 / s、4*10 -5 m 2 / s, 3*10 -5 m 2 / s、5*10 -6 m 2 / s etc.

[0161] The thermal conductivity of the first metal layer 11 and the thermal conductivity of the second metal layer 12 may be the same or different. When the thermal conductivity of the first metal layer 11 and the thermal conductivity of the second metal layer 12 are the same, the first metal layer 11 and the second metal layer 12 are made of the same material.

[0162] In some embodiments, the thermal conductivity of the first metal layer 11 is less than that of the second metal layer 12, which means that the thermal conductivity of the first metal layer 11 is worse than that of the second metal layer 12. In this case, the heat transfer capacity of the first metal layer 11 is weaker, and the temperature of the outer surface of the first metal layer 11 can be lower, which can better solve the problem of hot hands.

[0163] The thermal diffusivity of the first metal layer 11 and the thermal diffusivity of the second metal layer 12 may be the same or different. When the thermal diffusivity of the first metal layer 11 and the thermal diffusivity of the second metal layer 12 are the same, the first metal layer 11 and the second metal layer 12 are made of the same material.

[0164] In some embodiments, the thermal diffusivity of the first metal layer 11 is less than that of the second metal layer 12, which means that the thermal conductivity of the first metal layer 11 is worse than that of the second metal layer 12. In this case, the first metal layer 11 has a weaker ability to transfer heat, and the temperature of the outer surface of the first metal layer 11 can be lower, which can better solve the problem of hot hands.

[0165] See also some possible implementations. Figure 10 and Figure 11 The porous structure includes multiple sub-holes 14 distributed on the second metal layer 12. The centerline of each sub-hole 14 extends parallel to the thickness direction of the back cover 10, or the centerline of each sub-hole 14 intersects the thickness direction of the back cover 10 but is not perpendicular to it. The multiple sub-holes 14 can be regularly distributed on the second metal layer 12, or they can be irregularly distributed on the second metal layer 12.

[0166] There are no restrictions on the areas where sub-holes 14 are provided on the second metal layer 12. For example, sub-holes 14 may not be provided in areas of the back cover 10 where high strength support is required, or a smaller number of sub-holes 14 may be provided. Similarly, a larger number of sub-holes 14 and / or large-sized sub-holes 14 may be provided in areas of the back cover 10 where high strength support is not required.

[0167] The diameters of the multiple sub-holes 14 can be the same, or the diameters of the multiple sub-holes 14 can be different, or some of the multiple sub-holes 14 can have the same diameter and others can have different diameters.

[0168] There is no limitation on the diameter of the sub-hole 14. In some embodiments, the diameter of the sub-hole 14 may be less than or equal to 3 mm. Of course, the diameter of the sub-hole 14 may also be greater than 3 mm.

[0169] In some embodiments, along a direction perpendicular to the thickness direction of the rear cover 10 (e.g. Figure 11In the X or Y direction, the hole spacing between two adjacent sub-holes 14 can be greater than or equal to 0.2mm, which helps to reduce the machining difficulty of the sub-holes 14.

[0170] The shape of the sub-hole 14 can be a blind hole (e.g.) Figure 10 or Figure 11 (As shown) or through hole. The sub-hole 14 can be a circular blind hole, a square blind hole, or other blind hole. The sub-hole 14 can also be a circular through hole, a square through hole, or other through hole.

[0171] In some embodiments, all sub-holes 14 have the same structure; for example, all sub-holes 14 are blind holes, or all sub-holes 14 are through holes. In other embodiments, some of the sub-holes 14 have the same structure, while others have different structures; for example, some sub-holes 14 may be blind holes, while others may be through holes.

[0172] In some embodiments, such as Figure 11 As shown, each sub-hole 14 can be a blind hole located inside the second metal layer 12. The inner side of the second metal layer 12 is the side of the second metal layer 12 away from the first metal layer 11 along the thickness direction of the back cover 10. This increases the contact area between the second metal layer 12 and the third metal layer 13 or the first metal layer 11, which helps to improve the connection strength between the second metal layer 12 and the first or third metal layer 13. In addition, it can also optimize the manufacturing process of the back cover 10, reduce the number of process steps, and improve the manufacturing efficiency of the back cover 10. Finally, the first metal layer 11 and the second metal layer 12 can be connected together first, and then the second metal layer 12 can be etched to form the sub-hole 14 without etching through the second metal layer 12, thus protecting the first metal layer 11 from being affected.

[0173] Of course, in addition to being blind holes, each sub-hole 14 in some embodiments may also be a through hole penetrating the second metal layer 12 along the thickness direction of the back cover 10. In still other embodiments, some of the sub-holes 14 are through holes penetrating the second metal layer 12 along the thickness direction of the back cover 10, while the other part of the sub-holes 14 are blind holes located inside the second metal layer 12.

[0174] It should be noted that when the back cover 10 and the frame 12b form a unibody architecture back shell 140, at least a portion of the planar area of ​​the back cover 10 is provided with sub-holes 14.

[0175] Figure 12 for Figure 8 A schematic diagram at point D in the middle.

[0176] In some possible implementations, such as Figure 12As shown, the second metal layer 12 includes a central region 121 and an edge region 122, with the edge region 122 surrounding the central region 121. A sub-hole 14 is located inside the central region 121 and outside the edge region 122. This allows the adhesive to be placed between the edge region 122 of the second metal layer 12 and the middle frame 120, enabling bonding between the back cover 10 and the middle frame 120. Furthermore, the sub-hole 14's location outside the edge region 122 ensures a larger bonding area between the adhesive and the back cover 10, without reducing the bonding area between the back cover 10 and the adhesive, thus guaranteeing the structural strength of the adhesive assembly between the middle frame 120 and the back cover 10.

[0177] The specific width of the edge region 122 is not limited here. For example, it can be along a direction perpendicular to the thickness direction of the back cover 10 (e.g., ...). Figure 12 In the X or Y direction, the width of the edge area 122 is greater than or equal to 0.5 mm and less than or equal to 3 mm. This ensures that the edge area 122 has sufficient width to fit the adhesive backing, ensuring the bonding strength between the back cover 10 and the middle frame 120. At the same time, making the edge area 122 narrower results in a larger area of ​​the central area 121, allowing for a greater number of sub-holes 14, which helps to further reduce the heat transfer channels of the back cover 10.

[0178] It should be noted that the direction perpendicular to the thickness direction of the back cover 10 (e.g.) Figure 12 (In the X or Y direction), the width of the edge area 122 can also be greater than 3mm, such as 4mm, 5mm, etc.

[0179] It should also be noted that the width of the edge area 122 can be different at different points along the circumference of the back cover 10. In this case, the minimum width of the edge area 122 is greater than or equal to 0.5mm, and the maximum width of the edge area 122 can be less than or equal to 3mm, or the maximum width of the edge area 122 can also be greater than or equal to 3mm.

[0180] In some possible implementations, such as Figure 10 As shown, the first metal layer 11 is a single-layer structure.

[0181] Figure 13 This is a cross-sectional schematic diagram of the second type of back cover provided in Embodiment 1 of this application.

[0182] In some other possible implementations, the first metal layer 11 includes a layer along the thickness direction of the rear cover 10 (e.g., ...). Figure 13 Multiple sub-metal layers 111 arranged side-by-side in the Z-direction, for example Figure 13 As shown, the first metal layer 11 is composed of two stacked sub-metal layers 111. Of course, the number of sub-metal layers 111 can also exceed two. Thus, the first metal layer 11 composed of multiple sub-metal layers 111 is a multi-layer structure.

[0183] When the first metal layer 11 is a multilayer structure, the side of the first metal layer 11 closest to the second metal layer 12 is connected to the second metal layer 12 along the thickness direction of the back cover 10. In addition, the thicknesses of the multiple sub-metal layers 111 in the thickness direction of the back cover 10 may be different, or at least two sub-metal layers 111 may have the same thickness in the thickness direction of the back cover 10.

[0184] In some embodiments, the material type of two adjacent sub-metal layers 111 can be the same. For example, the material type of two adjacent sub-metal layers 111 can both be aluminum alloy. When the material types of two adjacent sub-metal layers 111 are the same, their specific compositions can be the same or different. For example, one sub-metal layer 111 can be a 6-series aluminum alloy, and the other sub-metal layer 11 can be a 7-series aluminum alloy. When the specific compositions of two adjacent metal layers 11 are different, the connection strength between the first metal layer 11 and the second metal layer 12 can be improved, thus increasing the overall connection strength between them.

[0185] In other embodiments, the material types of two adjacent sub-metal layers 11 may also be different. For example, one of the two adjacent sub-metal layers 111 may be made of aluminum alloy and the other may be made of titanium.

[0186] In some possible implementations, the first metal layer 11 and the second metal layer 12 are directly connected, which can reduce the number of layers constituting the back cover 10, reduce the thickness of the back cover 10, and help the back cover 10 achieve a thinner and lighter design.

[0187] In one embodiment, the first metal layer 11 is welded to the second metal layer 12, for example, by laser welding. Welding the first metal layer 11 and the second metal layer 12 can be applied to scenarios where the connection strength requirement is not high, thus reducing costs.

[0188] In another embodiment, the first metal layer 11 and the second metal layer 12 are diffusion bonded. Diffusion bonding is a joining technique between solid materials that achieves bonding by promoting the diffusion of atoms between contact surfaces under high temperature and pressure. This technique does not use filler metals or other additives, but relies on the atomic movement of the material itself to form a strong joint. Due to atomic-level diffusion and bonding, the resulting joint strength approaches or can even reach the level of the base material. Therefore, using diffusion bonding to connect the first metal layer 11 and the second metal layer 12 can be applied to scenarios requiring high connection strength, ensuring that the back cover 10 does not delaminate during processing and use.

[0189] In summary, the first metal layer 11 and the second metal layer 12 can be directly connected through welding or diffusion bonding. Of course, in addition to direct connection, the first metal layer 11 and the second metal layer 12 can also be indirectly connected in some scenarios.

[0190] Figure 14 This is a cross-sectional schematic diagram of the third type of back cover provided in Embodiment 1 of this application.

[0191] In some possible implementations, such as Figure 14 As shown, the back cover 10 also includes a third metal layer 13, along the thickness direction of the back cover 10 (e.g., ...). Figure 14 In the Z direction, the third metal layer 13 is located between the first metal layer 11 and the second metal layer 12. The first metal layer 11 is fixedly connected to the second metal layer 12 through the third metal layer 13, which can achieve better interlayer bonding.

[0192] In one embodiment, the third metal layer 13 is welded to the first metal layer 11, which can be applied to scenarios where the connection strength requirement is not high. In another embodiment, the third metal layer 13 is diffuse-bonded to the first metal layer 11, which can be applied to scenarios where the connection strength requirement is high.

[0193] In one embodiment, the third metal layer 13 is welded to the second metal layer 12, which can be applied to scenarios where the connection strength requirement is not high. In another embodiment, the third metal layer 13 is diffuse-bonded to the second metal layer 12, which can be applied to scenarios where the connection strength requirement is high.

[0194] There are no restrictions on the material of the third metal layer 13. For example, the material of the third metal layer 13 can be aluminum alloy, titanium, stainless steel, or nickel-based alloy, etc.

[0195] In some embodiments, the first metal layer 11, the second metal layer 12, and the third metal layer 13 are all made of different materials. For example, the first metal layer 11 is made of aluminum alloy, the second metal layer 12 is made of titanium, and the third metal layer 13 is made of stainless steel.

[0196] In some embodiments, at least two of the first metal layer 11, the second metal layer 12, and the third metal layer 13 are made of the same material. For example, the first metal layer 11 and the second metal layer 12 are both made of aluminum alloy, and the third metal layer 13 is made of titanium. Alternatively, the first metal layer 11 is made of aluminum alloy, and the second metal layer 12 and the third metal layer 13 are both made of titanium.

[0197] It should be noted that when the first metal layer 11 and the third metal layer 13 are made of the same material type, their specific compositions may be the same or different. Similarly, when the second metal layer 12 and the third metal layer 13 are made of the same material type, their specific compositions may be the same or different.

[0198] In some possible implementations, the outer surface of the first metal layer 11 serves as the outer surface of the back cover 10, and the first metal layer 11 is the surface structure of the back cover 10.

[0199] Figure 15 This is a cross-sectional structural diagram of the fourth type of back cover provided in Embodiment 1 of this application.

[0200] In some other possible implementations, the back cover 10 also includes a surface treatment layer 17 located on the outer surface of the first metal layer 11, that is, the surface treatment layer 17 and the second metal layer 12 are located on opposite sides of the first metal layer 11.

[0201] In this way, by setting the surface treatment layer 17, a differentiated metallic appearance effect can be achieved. In addition, the wear resistance and corrosion resistance of the back cover 10 can be improved.

[0202] It is understood that the surface treatment layer 17 is a layer structure formed by surface treatment of the outer surface of the first metal layer 11, such as anodizing, painting, electroplating and other surface treatments on the outer surface of the first metal layer 11.

[0203] In one embodiment, the surface treatment layer 17 may include an oxide layer located on the outer surface of the first metal layer 11, making the outer surface of the first metal layer 11 more wear-resistant and resistant to environmental corrosion, and achieving a differentiated appearance effect.

[0204] During the manufacturing process of the back cover 10, an oxide layer is formed by anodizing the first metal layer 11. The specific composition of the oxide layer is related to the material of the first metal layer 11. For example, if the material of the first metal layer 11 is aluminum alloy, the material of the oxide layer is aluminum oxide.

[0205] In one embodiment, the surface treatment layer 17 may include an oxide layer and a film layer. The oxide layer is located on the outer surface of the first metal layer 11 and between the first metal layer 11 and the film layer. The film layer is disposed on the outer surface of the oxide layer and can be used to prevent fingerprints.

[0206] In one embodiment, the surface treatment layer 17 may include a metal coating, which is formed by coating the outer surface of the first metal layer 11.

[0207] Figure 16 This is a three-dimensional structural diagram of the fifth type of back cover provided in Embodiment 1 of this application.

[0208] In some possible implementations, such as Figure 16 As shown, the back cover 10 also includes a second through hole 16 and a non-metallic component (not shown in the figure). The second through hole 16 extends through the back cover 10 along its thickness direction. At least a portion of the non-metallic component is located inside the second through hole 16. The non-metallic component serves to shield the wireless charging coil inside the electronic device 100, enhance the appearance, and provide waterproofing.

[0209] Along the thickness direction of the back cover 10, the orthographic projection of the wireless charging coil (not shown in the figure) on the back cover 10 is located inside the second through hole 16. By placing the coil that enables wireless charging inside the electronic device 100 inside the second through hole 16, there are no metal objects between the transmitting coil and the receiving coil that enable wireless charging in the thickness direction of the electronic device 100, which can improve the efficiency of wireless charging, improve safety, and protect the health of the electronic device 100.

[0210] In some possible implementations, the inner wall of the second through hole 16 can be formed by at least the first metal layer 11 and the second metal layer 12, that is, the second through hole 16 penetrates the first metal layer 11 and the second metal layer 12 at least along the thickness direction of the back cover 10.

[0211] In one embodiment, the back cover 10 includes a first metal layer 11 and a second metal layer 12. In this case, the second through hole 16 penetrates the first metal layer 11 and the second metal layer 12 along the thickness direction of the back cover 10, and the inner wall of the second through hole 16 is formed by the first metal layer 11 and the second metal layer 12.

[0212] In one embodiment, the back cover 10 includes a first metal layer 11, a second metal layer 12, and a surface treatment layer 17. In this case, the second through hole 16 penetrates the first metal layer 11, the second metal layer 12, and the surface treatment layer 17 along the thickness direction of the back cover 10. The inner wall of the second through hole 16 is formed by the first metal layer 11, the second metal layer 12, and the surface treatment layer 17.

[0213] In one embodiment, the back cover 10 includes a first metal layer 11, a second metal layer 12 and a third metal layer 13. In this case, the second through hole 16 penetrates the first metal layer 11, the second metal layer 12 and the third metal layer 13 along the thickness direction of the back cover 10, and the inner wall of the second through hole 16 is formed by the first metal layer 11, the second metal layer 12 and the third metal layer 13.

[0214] In one embodiment, the back cover 10 includes a first metal layer 11, a second metal layer 12, a third metal layer 13, and a surface treatment layer 17. In this case, the second through hole 16 penetrates the first metal layer 11, the second metal layer 12, the third metal layer 13, and the surface treatment layer 17 along the thickness direction of the back cover 10. The inner wall of the second through hole 16 is formed by the first metal layer 11, the second metal layer 12, the third metal layer 13, and the surface treatment layer 17.

[0215] Figure 17 This is a three-dimensional structural diagram of the sixth type of back cover provided in Embodiment 1 of this application. Figure 18 for Figure 17 A cross-sectional view along the EE direction. Figure 19 for Figure 18 A schematic diagram at point R in the middle.

[0216] In some possible implementations, such as Figure 19 As shown, the first metal layer 11 includes a first portion 112 and a second portion 113. Wherein, combined with Figures 17 to 19 It can be seen that the second metal layer 12 is located inside the first part 112, and the orthographic projection of the second metal layer 12 onto the first metal layer 11 does not coincide with the second part 113. The second through hole 16 penetrates the second part 113 along the thickness direction of the back cover, and extends along the direction perpendicular to the center line of the second through hole 16 (e.g., Figure 19 The direction of the Z-direction (e.g.) Figure 19 (in the Y direction), the second through hole 16 and the second metal layer 12 are spaced apart.

[0217] It is understandable that the second through-hole 1616 and the second metal layer 1212 are spaced apart along a direction perpendicular to the centerline of the second through-hole 1616, meaning that the second through-hole 1616 and the second metal layer 1212 are staggered, and the second through-hole 1616 does not penetrate the second metal layer 1212. In this way, the sidewall of the second through-hole 16 is mainly composed of the first metal layer 11, avoiding the possibility that part of the sidewall of the second through-hole 16 is formed by the second metal layer 12. While ensuring high wireless charging efficiency, the second metal layer 12 can be made of materials that significantly affect wireless charging, such as titanium.

[0218] Among them, the impact of wireless charging mainly refers to the skin effect generated on the surface of metal materials by the wireless charging frequency. The skin effect has a heating effect on metals. Based on the skin effect and heating mechanism, combined with the physical properties of different metal materials, for example, the heating effect of aluminum alloy is much lower than that of titanium alloy.

[0219] In some embodiments, such as Figure 19As shown, the distance between the outer surface of the first portion 112 and the inner surface of the second metal layer 12 is equal to the thickness of the second portion 113. In this way, the second portion 113 can separate the second metal layer 12 from the second through hole 16.

[0220] In some embodiments, such as Figure 19 As shown, along the direction from the edge of the back cover 10 to the center line of the second through hole 16, the maximum thickness of the second metal layer 12 gradually decreases in the direction of extension of the center line of the second through hole 16, while the maximum thickness of the first metal layer 11 gradually increases in the direction of extension of the center line of the second through hole 16.

[0221] It should be noted that the width of the second part 113 in the direction perpendicular to the thickness of the back cover 10 is not limited here. For example, the width of the second part 113 can also be greater than... Figure 19 The width of the second part 113 shown.

[0222] For example, such as Figure 19 As shown, the inner wall of the second through hole 16 is the first metal layer 11. However, in some embodiments, when the back cover 10 also includes a surface treatment layer 17, a portion of the inner wall of the second through hole 16 is the first metal layer 11 and another portion of the inner wall is the surface treatment layer 17.

[0223] Figure 20 This is a three-dimensional structural diagram of the seventh type of back cover provided in Embodiment 1 of this application.

[0224] In some possible implementations, such as Figure 20 As shown, the back cover 10 also includes a protruding structure 18, which is fixedly connected to the inner surface of the second metal layer 12. The protruding structure 18 is used to realize assembly, limiting, positioning, structural support and other functions.

[0225] The number of protrusions 18 can be one or more, for example Figure 20 As shown, there are two protrusions 18. Of course, the number of protrusions 18 can be less or more than two.

[0226] The specific location of the protrusion 18 on the second metal layer 12 is not limited here. For example, the protrusion 18 can be located near the first through hole 15.

[0227] There are no restrictions on the shape of the protruding structure 18. For example... Figure 20 As shown, the protruding structure 18 can be a strip structure.

[0228] In some embodiments, the protrusion structure 18 may be made of a metallic material. The protrusion structure 18 can be connected to the second metal layer 12 by welding. Alternatively, it can be connected to the second metal layer 12 by adhesive bonding or snap-fitting.

[0229] In other embodiments, the protrusion structure 18 may also be made of a non-metallic material. The protrusion structure 18 may be connected to the second metal layer 12 by means of bonding, snap-fitting, or other methods.

[0230] Figure 21 This is a cross-sectional schematic diagram of the eighth type of back cover provided in Embodiment 1 of this application. Figure 22 This is a cross-sectional schematic diagram of the ninth type of back cover provided in Embodiment 1 of this application.

[0231] In some possible implementations, such as Figure 21 As shown, the back cover 10 also includes a protective layer 30, which covers the sidewall of the first metal layer 11 and the sidewall of the second metal layer 12. The protective layer 30 isolates liquids such as sweat from contacting the first metal layer 11 and / or the second metal layer 12, thereby preventing electrochemical corrosion between the first metal layer 11 and the second metal layer 12.

[0232] The protective layer 30 can be a polymer layer, paint layer, etc., and there are no restrictions here.

[0233] It should be noted that when the back cover 10 also includes a surface treatment layer 17, such as Figure 22 As shown, the protective layer 30 can also cover the sidewalls of the surface treatment layer 17.

[0234] Figure 23 This is a cross-sectional schematic diagram of the tenth type of back cover provided in Embodiment 1 of this application.

[0235] In some possible implementations, when an intermediate layer connecting the first metal layer 11 and the second metal layer 12 is provided, the protective layer 30 covers the sidewalls of the first metal layer 11, the second metal layer 12, and the intermediate layer. For example, the intermediate layer is a third metal layer 13 located between the first metal layer 11 and the second metal layer 12. Figure 23 As shown, the protective layer 30 covers the sidewalls of the first metal layer 11, the second metal layer 12, and the third metal layer 13.

[0236] It should be noted that, in addition to being composed of a third metal layer 13, in some embodiments, the intermediate layer may also include multiple layers of stacked metal layers.

[0237] Figure 24 This is a schematic diagram of step one of the methods for preparing a back cover assembly according to Embodiment 1 of this application. Figure 25This is a schematic diagram of step two of a method for preparing a back cover assembly according to Embodiment 1 of this application.

[0238] This embodiment also provides a method for preparing a back cover assembly 110, which includes the following steps:

[0239] S1. Preparation of composite metal plates, such as Figure 24 As shown, the composite metal plate includes a first metal plate and a second metal plate stacked together.

[0240] Specifically, the first metal plate can be made of aluminum alloy, and the second metal plate can be made of titanium. Therefore, the first metal plate can also be called an aluminum plate, and the second metal plate can also be called a titanium plate. The first metal plate is used to form the first metal layer 11, and the second metal plate is used to form the second metal layer 12. Figure 24 As shown, titanium plate / strip raw materials and aluminum plate / strip raw materials are subjected to certain surface treatments (such as grinding, cleaning, etc.) and then diffusion composites (including rolling, isostatic pressing, thermal diffusion, welding, etc.) to form titanium-aluminum composite materials, and inter-atomic diffusion bonding of titanium and aluminum is generated between the layers.

[0241] For example, the aluminum alloy can be selected from 6 series such as 6013 aluminum alloy or 7 series aluminum alloy, with a thickness of 0.1 to 0.2 mm; the titanium alloy can be selected from TA4, with a thickness of 0.3 to 0.5 mm.

[0242] S2. Prepare the back cover material structure.

[0243] Specifically, based on the external dimensions of the back cover 10, the composite metal plate is processed to create the structural shape and structural features for assembly with other components or devices, such as the first through hole 15 for the assembly of the rear camera module, to obtain the back cover material structure, which has a first metal layer 11 and a second metal layer 12.

[0244] S3. A porous structure is prepared on the second metal layer 12, the porous structure including a plurality of sub-pores 14.

[0245] The sub-hole 14 can be a blind hole located on the inner side of the second metal layer 12 away from the first metal layer 11. Of course, in some embodiments, the sub-hole can also be a through hole penetrating the second metal layer 12 along the thickness direction of the rear cover 10.

[0246] In some embodiments, a method for preparing a porous structure may include the following steps:

[0247] S301. The inner surface of the second metal layer 12 of the back cover 10 is masked with a film. Different masking areas are designed on the film (to mask the positions where openings are required). Then, the whole thing is coated with electrophoretic paint. After electrophoresis, the film is removed.

[0248] S302. Place the back cover material structure into the etching tank and etch the second metal layer 12. Blind holes are etched in the areas not covered by electrophoretic paint, forming sub-holes 14. Multiple sub-holes 14 constitute a structure as shown in the image. Figure 11 The porous structure shown provides the material for the back cover. Blind holes are placed in the second metal layer 12, meaning that the second metal layer 12 is not etched through, thus protecting the first metal layer 11 from being affected.

[0249] S4. Perform surface treatment on the back cover material to obtain back cover 10.

[0250] Specifically, after surface treatment such as surface polishing / sandblasting / wire drawing is performed on the etched battery cover material, anodizing is then performed to form an oxide layer on the outer surface of the first metal layer 11, making the surface of the first metal layer 11 more wear-resistant and resistant to environmental corrosion, and achieving a differentiated appearance effect.

[0251] S5, such as Figure 25 As shown, the camera trim 20 and the back cover 10 are assembled to form the back cover assembly 110.

[0252] Specifically, the back cover 10 can be connected to the camera trim 20 using adhesive backing.

[0253] Example 2

[0254] The difference between this embodiment and embodiment one is that the second metal layer 12 is made of a porous metal material. A porous metal material refers to a metal material containing a large number of pores (porosity typically >20%), whose structure consists of a metal matrix and pores. The pore morphology can be open (interconnected) or closed (independently sealed). Thus, the pores of the porous metal material form a porous structure, reducing heat transfer and heat storage, thereby reducing the heat transferred to the first metal layer 11, achieving good heat insulation, and solving the problem of the material feeling hot to the touch. In addition, the low density of the porous metal material makes the second metal layer 12 lightweight, reducing the weight of the back cover 10 and achieving a lightweight design for the back cover 10.

[0255] In some embodiments, the porous metallic material is a foamed metallic material, also known as foamed metal. Foamed metal is a porous material formed by introducing a large number of pores (closed or open) into a metallic matrix through physical or chemical methods. Its structure is similar to that of foamed plastics, but the matrix is ​​metallic, combining lightweight properties with the mechanical and thermal properties of metals. These pores can be formed in a metallic matrix (e.g., pure metal or alloy) through specific processes, such as using foaming agents, powder metallurgy, or injecting gas into molten metal.

[0256] The numerous pores within the foamed metal material create a porous structure, reducing heat transfer channels in the second metal layer 12 and achieving excellent thermal insulation. The foamed metal material has high strength and elastic modulus, providing better support stiffness for the overall structure of the back cover 10. Due to the low density of the foamed metal material, the second metal layer 12 is lightweight, resulting in minimal increase in the overall weight of the back cover 10.

[0257] Foamed metal materials can be foamed titanium, foamed nickel, foamed iron, foamed magnesium, etc.

[0258] Foamed metal materials can be prepared by methods such as melt foaming, powder metallurgy, and 3D printing.

[0259] In some embodiments, the porous metal material is metal fiber felt, also known as sintered metal fiber felt. Metal fiber felt is a flexible porous mesh material formed by the disordered interweaving of metal fibers (micron-sized filaments) and sintering to fix them; or, in other words, metal fiber felt refers to a felt-like material made by sintering metal fibers at high temperatures. Its pores are formed by the gaps between the fibers, giving it a high specific surface area and permeability.

[0260] The porous structure of the metal fiber felt reduces the heat transfer channels of the second metal layer 12, achieving good thermal insulation. The high strength and elastic modulus of the metal fiber felt provide better support stiffness for the overall structure of the back cover 10. Due to the low density of the metal fiber felt, the second metal layer 12 is lightweight, resulting in only a minimal increase in the overall weight of the back cover 10.

[0261] Depending on the base material, metal fiber felt can be divided into stainless steel fiber felt, titanium fiber felt, nickel fiber, etc.

[0262] In summary, when the porous metal material is a foamed metal material (e.g., foamed titanium material) or a metal fiber felt (e.g., titanium fiber felt), it forms a porous structure through its own pores. It does not require etching holes on the second metal layer to form a porous structure, which simplifies the preparation difficulty of the porous structure, reduces the process steps of the back cover 10, improves the production efficiency of the back cover 10, and reduces the cost of the back cover 10.

[0263] In some embodiments, the second metal layer 12 made of porous metal material can be directly connected to the first metal layer 11.

[0264] In other embodiments, the second metal layer 12, made of a porous metal material, can be connected to the first metal layer 11 via a third metal layer 13. For example, the second metal layer 12 is made of a foamed metal material, the third metal layer 13 is made of titanium, and the first metal layer 11 is made of an aluminum alloy.

[0265] In this process, the first metal layer 11 and the second metal layer 12 can be diffusely bonded, thereby forming a titanium-aluminum composite material with titanium-aluminum atoms diffusely bonded between the layers. For example, the aluminum alloy can be selected from 6-series such as 6013 aluminum alloy or 7-series aluminum alloy, with a thickness of 0.1 to 0.2 mm; the titanium alloy can be selected from TA4, with a thickness of 0.05 to 0.15 mm.

[0266] Figure 26 This is a schematic diagram of step one of the methods for preparing a back cover assembly according to Embodiment 2 of this application. Figure 27 This is a schematic diagram of step two of a method for preparing a back cover assembly according to Embodiment 2 of this application.

[0267] This second embodiment also provides a method for preparing a back cover assembly 110, which includes the following steps:

[0268] S1. Prepare a composite metal plate, which includes a first metal plate and a second metal plate stacked together.

[0269] Specifically, the first metal plate can be made of aluminum alloy, and the second metal plate can be made of titanium. Therefore, the first metal plate can also be called an aluminum plate, and the second metal plate can also be called a titanium plate. The first metal plate is used to form the first metal layer 11, and the second metal plate is used to form the third metal layer 13. After certain surface treatments (such as grinding, cleaning, etc.) of the titanium plate / strip raw materials and the aluminum plate / strip raw materials, diffusion composites (including rolling, isostatic pressing, thermal diffusion, welding, etc.) are performed to form a titanium-aluminum composite material, resulting in inter-atomic diffusion bonding between the layers.

[0270] For example, the aluminum alloy can be selected from 6 series such as 6013 aluminum alloy or 7 series aluminum alloy, with a thickness of 0.1 to 0.2 mm; the titanium alloy can be selected from TA4, with a thickness of 0.3 to 0.5 mm.

[0271] S2. Provide perforated metal plates.

[0272] Specifically, the porous metal plate is made of a porous metal material, such as a foamed metal material. The foamed metal material has continuous or discontinuous pores inside, is lightweight, and has good thermal insulation properties. For example, the porous metal plate is made of foamed titanium material. The porous metal plate is used to form the second metal layer 12.

[0273] S3. Prepare a composite layer formed by the second metal layer 12, the first metal layer 11, and the third metal layer 13.

[0274] Specifically, refer to Figure 26As shown, based on the external dimensions of the back cover 10, the composite metal plate and the porous metal plate are processed to create the structural shape and structural features for assembly with other components or devices, such as the first through hole 15 for assembling the rear camera module. The composite metal plate is used to form a composite layer, and the porous metal plate is used to form a second metal layer 12.

[0275] S4. Assemble the composite layer and the second metal layer 12 to obtain the back cover material structure.

[0276] Specifically, such as Figure 27 As shown, the second metal layer 12 and the third metal layer 13 in the composite layer are welded by laser welding. Both the second metal layer 12 and the third metal layer 13 are titanium alloys, which is more conducive to the welding structure and has high reliability.

[0277] S5. Perform surface treatment on the back cover material structure to obtain back cover 10.

[0278] Specifically, after surface treatment such as surface polishing / sandblasting / wire drawing is performed on the etched battery cover material, anodizing is then performed to form an oxide layer on the outer surface of the first metal layer 11, making the surface of the first metal layer 11 more wear-resistant and resistant to environmental corrosion, and achieving a differentiated appearance effect.

[0279] S6, Assemble camera trim 20 and back cover 10.

[0280] Specifically, the back cover 10 can be connected to the camera trim 20 using adhesive backing.

[0281] It should be noted that in some scenarios, the porous metal plate in step S2 can be replaced with a dense solid metal plate (e.g., a dense solid titanium plate), and then the dense solid metal plate can be etched to form blind holes, thereby obtaining a second metal layer 12 with a porous structure.

[0282] Example 3

[0283] Figure 28 This is a top view of the first type of back cover provided in Embodiment 3 of this application. Figure 29 for Figure 28 A cross-sectional view along the AA direction. Figure 30 This is a cross-sectional schematic diagram of the second type of back cover provided in Embodiment 3 of this application. Figure 31 This is a cross-sectional schematic diagram of the third type of back cover provided in Embodiment 3 of this application.

[0284] The difference between Embodiment 3 and Embodiment 1 is that the second metal layer 12 includes at least two metal portions that are joined together, for example... Figure 28 As shown, the number of metal parts is three (e.g., Figure 28(123 and 124 in the original text), of course, the number of metal parts can be less than or more than three. Along the direction perpendicular to the thickness direction of the back cover 10, the orthogonal projections of two adjacent metal parts on the first metal layer 11 do not overlap at least partially. In this way, the second metal layer 12 is a split structure composed of multiple metal parts, which can be specifically designed according to the heat generation of different areas inside the electronic device 100, the strength requirements of different areas of the back cover 10, etc., to further optimize the strength and / or heat insulation effect of the second metal layer 12.

[0285] In some embodiments, such as Figure 29 As shown, along the direction perpendicular to the thickness direction of the back cover 10 (e.g.) Figure 29 In the Y direction, the orthographic projections of two adjacent metal parts on the first metal layer 11 do not coincide.

[0286] In other embodiments, such as Figure 30 As shown, along the direction perpendicular to the thickness direction of the back cover 10 (e.g.) Figure 30 In the Y direction, the orthographic projections of two adjacent metal parts on the first metal layer 11 overlap.

[0287] In some embodiments, adjacent metal portions are welded along a direction perpendicular to the thickness direction of the back cover 10. This welding method joins adjacent metal portions together. Additionally, it increases the connection strength between adjacent metal portions, thereby improving the overall strength of the second metal layer 12.

[0288] In some embodiments, two adjacent metal parts can also be connected by adhesive bonding along a direction perpendicular to the thickness direction of the back cover 10, which can be applied to scenarios where the back cover 10 has a large strength redundancy.

[0289] In some possible implementations, such as Figure 30 As shown, at least two metal portions include a first metal portion 123 and a second metal portion 124. A porous structure is disposed in the first metal portion 123, and the second metal portion 124 is a solid metal portion. In this way, by placing the second metal portion 124 in the area requiring strength support, the overall strength of the second metal layer 12 is optimized while reducing heat transfer.

[0290] The metal parts can be divided into two categories based on whether they have a porous structure. One category is designated as the first metal part 123, and the other category is designated as the second metal part 124. The number of first metal parts 123 is at least one, and the number of second metal parts 124 is at least two.

[0291] It is understandable that the second metal part 124 is a solid metal part, meaning that the second metal part 124 is made of solid metal material.

[0292] It should be noted that when the second metal layer 12 is formed by splicing at least two second metal parts 124, the second metal layer 12 can be directly connected to the first metal layer 11, or the second metal layer 12 can also be connected to the first metal layer 11 through an intermediate layer (such as a third metal layer 13). Figure 31 As shown.

[0293] In some embodiments, the material of any one of the first metal portions 123 is a porous metal material, and the pores of the porous metal material constitute a porous structure. For example, the material of the first metal portion 123 is a foamed metal material.

[0294] In some embodiments, the porous structure of any first metal portion 123 may include a plurality of sub-holes 14.

[0295] In some embodiments, the number of first metal portions 123 is at least two, and one of the at least two first metal portions 123 has subpores 14 constituting a porous structure, while the other portion is made of a porous metal material.

[0296] In some possible implementations, the first metal portion 123 and the second metal portion 124 are made of different materials. In this way, different requirements can be met by controlling the materials of the first metal portion 123 and the second metal portion 124.

[0297] In one embodiment, the different materials of the first metal part 123 and the second metal part 124 can be understood as the first metal part 123 and the second metal part 124 belonging to the same type of material, but their specific compositions are different. For example, the first metal part 123 and the second metal part 124 both belong to titanium metal materials, but the material of the first metal part 123 is foamed titanium and the material of the second metal part 124 is solid titanium.

[0298] When the material of the first metal part 123 is a porous metal material and the second metal part 124 is a solid metal material, the second metal part 124 can be connected to the first metal layer 11 first by welding or diffusion bonding, and then the first metal part 123 and the second metal part 124 can be connected by welding or bonding, for example, welding at the joint between the first metal part 123 and the second metal part 124.

[0299] It should be noted that when a third metal layer 13 is provided between the first metal layer 11 and the second metal layer 12, the third metal layer 13 and the first metal layer 11 can form a composite structure layer in advance. Then, the second metal part 124 can be connected to the composite structure layer by welding or diffusion bonding. Finally, the first metal part 123 and the second metal part 124 can be connected by welding or bonding. For example, welding can be performed at the joint between the first metal part 123 and the second metal part 124.

[0300] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances. The terms "first," "second," "third," "fourth," etc. (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0301] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A back cover (10), characterized in that, include: First metal layer (11); The second metal layer (12) is located inside the first metal layer (11) along the thickness direction of the rear cover (10), and the second metal layer (12) has a porous structure.

2. The rear cover (10) according to claim 1, characterized in that, The thermal conductivity of the second metal layer (12) is less than or equal to 50 W / (m·K), and / or the thermal diffusivity of the second metal layer (12) is less than or equal to 5*10 -5 m 2 / s.

3. The rear cover (10) according to claim 1 or 2, characterized in that, The porous structure includes multiple sub-holes (14), each of which is a blind hole and located inside the second metal layer (12). The inside of the second metal layer (12) is the side of the second metal layer (12) away from the first metal layer (11) along the thickness direction of the back cover (10).

4. The rear cover (10) according to claim 3, characterized in that, The second metal layer (12) includes: The central region (121) has the sub-hole (14) located inside the central region (121); The edge region (122) surrounds the central region (121).

5. The rear cover (10) according to claim 4, characterized in that, Along a direction perpendicular to the thickness direction of the back cover (10), the width of the edge region (122) is greater than or equal to 0.5 mm.

6. The rear cover (10) according to claim 5, characterized in that, The width of the edge region (122) is less than or equal to 3 mm.

7. The rear cover (10) according to claim 1 or 2, characterized in that, The material of the second metal layer (12) is a porous metal material.

8. The rear cover (10) according to claim 7, characterized in that, The porous metal material is either foam metal material or metal fiber felt.

9. The rear cover (10) according to any one of claims 1 to 8, characterized in that, The second metal layer (12) is integrally formed.

10. The rear cover (10) according to any one of claims 1 to 6, characterized in that, The second metal layer (12) includes at least two metal portions that are spliced ​​together, and the orthographic projections of two adjacent metal portions on the first metal layer (11) do not at least partially overlap in a direction perpendicular to the thickness direction of the back cover (10).

11. The rear cover (10) according to claim 10, characterized in that, The two adjacent metal portions are welded along a direction perpendicular to the thickness direction of the rear cover (10).

12. The rear cover (10) according to claim 10 or 11, characterized in that, The at least two metal parts include a first metal part (123) and a second metal part (124), the porous structure is disposed on the first metal part (123), and the second metal part (124) is a solid metal part.

13. The rear cover (10) according to claim 12, characterized in that, The first metal part (123) and the second metal part (124) are made of different materials.

14. The rear cover (10) according to any one of claims 1 to 13, characterized in that, The first metal layer (11) is directly connected to the second metal layer (12).

15. The rear cover (10) according to claim 14, characterized in that, The first metal layer (11) is welded to the second metal layer (12), or the first metal layer (11) and the second metal layer (12) are diffusely bonded.

16. The rear cover (10) according to any one of claims 1 to 13, characterized in that, The back cover (10) also includes a third metal layer (13), which is located between the first metal layer (11) and the second metal layer (12). The first metal layer (11) is fixedly connected to the second metal layer (12) through the third metal layer (13).

17. The rear cover (10) according to claim 16, characterized in that, The third metal layer (13) is welded to the first metal layer (11), or the third metal layer (13) is diffusely bonded to the first metal layer (11).

18. The rear cover (10) according to claim 16 or 17, characterized in that, The third metal layer (13) is welded to the second metal layer (12), or the third metal layer (13) is diffusely bonded to the second metal layer (12).

19. The rear cover (10) according to any one of claims 1 to 18, characterized in that, The first metal layer (11) is a single-layer structure, or the first metal layer (11) includes multiple sub-metal layers (111) arranged side by side along the thickness direction of the rear cover (10).

20. The rear cover (10) according to any one of claims 1 to 19, characterized in that, The material of the first metal layer (11) is aluminum alloy, titanium metal or stainless steel.

21. The rear cover (10) according to any one of claims 1 to 20, characterized in that, The material of the second metal layer (12) is titanium metal, iron-based metal, magnesium-based metal or nickel-based alloy.

22. The rear cover (10) according to any one of claims 1 to 21, characterized in that, The rear cover (10) further includes a first through hole (15), which penetrates the rear cover (10) along the thickness direction of the rear cover (10).

23. The rear cover (10) according to any one of claims 1 to 22, characterized in that, The rear cover (10) also includes: The second through hole (16) extends through the rear cover (10) along the thickness direction of the rear cover (10); The non-metallic part is located at least partially inside the second through hole (16).

24. The rear cover (10) according to claim 23, characterized in that, The first metal layer (11) includes a first portion (112) and a second portion (113); The second metal layer (12) is located inside the first part (112), and the orthographic projection of the second metal layer (12) onto the first metal layer (11) does not coincide with the second part (113); The second through hole (16) penetrates the second portion (113) along the thickness direction of the rear cover (10). The second through hole (16) and the second metal layer (12) are spaced apart along the extension direction perpendicular to the center line of the second through hole (16).

25. The rear cover (10) according to any one of claims 1 to 24, characterized in that, The back cover (10) also includes a surface treatment layer (17) located on the outer surface of the first metal layer (11).

26. The rear cover (10) according to claim 25, characterized in that, The surface treatment layer (17) includes an oxide layer located on the outer surface of the first metal layer (11).

27. The rear cover (10) according to any one of claims 1 to 26, characterized in that, The back cover (10) also includes a protruding structure (18) which is fixedly connected to the inner surface of the second metal layer (12).

28. The rear cover (10) according to any one of claims 1 to 27, characterized in that, The rear cover (10) further includes a protective layer (30) that covers the sidewalls of the first metal layer (11) and the sidewalls of the second metal layer (12); or, The back cover (10) also includes a protective layer (30) and an intermediate layer located between the first metal layer (11) and the second metal layer (12), the protective layer (30) covering the sidewalls of the first metal layer (11), the sidewalls of the second metal layer (12) and the sidewalls of the intermediate layer.

29. A rear shell (140), characterized in that, Includes a frame (12b) and a back cover (10) as claimed in any one of claims 1 to 27, the frame (12b) surrounding the outer edge of the back cover (10), the frame (12b) being integrally formed with the back cover (10).

30. A back cover assembly (110), characterized in that, Includes a camera trim (20) and a back cover (10) as claimed in any one of claims 1 to 28, or includes a camera trim (20) and a back shell (140) as claimed in claim 29, the back shell (140) including the back cover (10). The back cover (10) has a first through hole (15), and the camera decorative piece (20) is disposed at the first through hole (15) of the back cover (10) and is fixedly connected to the back cover (10).

31. An electronic device (100), characterized in that, Includes a display screen (130), a mid-frame (120), and a back cover (10) as described in any one of claims 1 to 28; The back cover (10) and the display screen (130) are located on opposite sides of the middle frame (120), and the back cover (10) and the display screen (130) are connected to the middle frame (120). The back cover (10), the middle frame (120) and the display screen (130) together form an accommodating space for the components. The back cover (10) includes a first metal layer (11) and a second metal layer (12). Along the thickness direction of the back cover (10), the second metal layer (12) is located between the outer surface of the first metal layer (11) and the middle frame (120).

32. An electronic device (100), characterized in that, Includes a display screen (130) and a rear cover (140) as described in claim 29; The back cover (140) is connected to the display screen (130) to form an accommodating space for the components. The back cover (140) includes a first metal layer (11) and a second metal layer (12). Along the thickness direction of the display screen (130), the second metal layer (12) is located between the outer surface of the display screen (130) and the first metal layer (11).

Images