Middle frame and electronic equipment

Abstract

The utility model provides a middle frame and electronic equipment. The middle frame comprises a frame and a middle plate, the frame is arranged around the middle plate in the circumferential direction and connected with the middle plate, the frame comprises a titanium-containing metal layer, the titanium-containing metal layer is a titanium layer or a titanium alloy layer, the middle plate is a magnesium alloy plate, and the titanium-containing metal layer is an appearance layer of the frame, so that the weight of the middle frame is reduced while the appearance and strength of the middle frame are improved.

Description

Technical Field

[0001] The present application relates to the field of electronic devices, and in particular to a middle frame and an electronic device. Background Art

[0002] The middle frames of existing 3C electronic products are typically made of aluminum alloy. Compared to aluminum alloy, titanium and titanium alloys offer a superior appearance and texture, significantly enhancing the aesthetics of the middle frame. Furthermore, titanium and titanium alloys, as aerospace metals, possess extremely high specific strength, high elastic modulus, and excellent corrosion resistance. When used in the middle frames of 3C products, they can effectively enhance the strength of the middle frames. However, due to their high density and price, using titanium or titanium alloys increases weight and cost. Compared to aluminum alloy, magnesium alloys have a lower density and lower price, which can help reduce weight and cost. However, magnesium alloys have a lower elastic modulus, significant anisotropy in strength, and poor corrosion resistance, which limit their application in 3C products. Therefore, achieving a balance between reducing weight and improving aesthetics and strength has become a key focus in the weight reduction and enhancement of middle frames in 3C products. However, current middle frame products are unable to achieve these goals. Utility Model Content

[0003] The present application provides a middle frame and an electronic device, so as to improve the appearance and strength of the middle frame while reducing the weight of the middle frame.

[0004] In the first aspect, the present application provides a middle frame, which includes a frame and a middle plate, the frame is arranged around the circumference of the middle plate and is connected to the middle plate, the frame includes a titanium-containing metal layer, the titanium-containing metal layer is the appearance layer of the frame, the titanium-containing metal layer is a titanium layer or a titanium alloy layer, and the middle plate is a magnesium alloy plate.

[0005] The middle frame of the present application has a frame including a titanium-containing metal layer. The titanium-containing metal layer serves as the appearance layer of the frame, which can enhance the overall aesthetics of the middle frame and give it a metallic texture unique to titanium. In addition, since the titanium-containing metal layer is a titanium layer or a titanium alloy layer, it has a high strength and can provide the frame with a higher structural strength and drop resistance, shock resistance, and corrosion resistance, thereby improving the strength and stability of the frame. Since the middle plate is often placed inside the electronic device, the use of a magnesium alloy plate will not affect the appearance performance of the middle frame, and the density of magnesium alloy is relatively low, and the area of ​​the middle plate is relatively large. Therefore, the use of a magnesium alloy plate for the middle plate can help reduce the overall weight of the middle frame. Thus, by using a titanium-containing metal layer to form the frame and a magnesium alloy plate to form the middle plate, the purpose of reducing the weight of the middle frame while enhancing the appearance and strength of the middle frame can be achieved.

[0006] In one optional implementation, an aluminum alloy layer is provided on the side of the titanium-containing metal layer facing the middle plate. Compared to titanium metal or titanium alloys, aluminum alloys and magnesium alloys can be welded together, simplifying the connection and improving the strength of the connection. Therefore, providing an aluminum alloy layer on the side of the titanium-containing metal layer facing the middle plate and utilizing the aluminum alloy layer to achieve connection with the middle plate can simplify the connection between the frame and the middle plate and improve the strength of the connection between the frame and the middle plate.

[0007] In an optional implementation, a magnesium alloy layer is provided on the side of the aluminum alloy layer facing the middle plate. The magnesium alloy layer and the magnesium alloy middle plate can achieve a better connection, for example, welding can be facilitated. The frame has a three-layer structure, namely a titanium-containing metal layer, an aluminum alloy layer and a magnesium alloy layer. Since the bonding force between the titanium-containing metal layer and the magnesium alloy layer is weak, the aluminum alloy layer and the titanium-containing metal layer can be connected with high strength by hot pressing, and the aluminum alloy layer and the magnesium alloy layer can also be connected with high strength by hot pressing. Therefore, by providing an aluminum alloy layer between the titanium-containing metal layer and the magnesium alloy layer, the overall structural strength of the frame can be improved.

[0008] In an optional implementation, a boss is provided on the side of the frame facing the middle plate, and the boss is connected to the middle plate. By providing the boss, the frame and the middle plate can be easily connected, for example, by riveting, plugging, bolting or welding.

[0009] In one optional implementation, when the side of the frame facing the middle plate is an aluminum alloy layer, the frame boss is an aluminum alloy boss. The aluminum alloy boss can be an integral structure with the aluminum alloy layer. That is, the aluminum alloy boss can be formed integrally with the aluminum alloy layer through processing. The aluminum alloy boss allows the boss to overlap the end of the middle plate, facilitating the connection between the frame and the middle plate. When the boss is an aluminum alloy boss, the connection between the boss and the middle plate can be welded, such as by spot welding or laser welding.

[0010] In one optional implementation, when the frame faces the magnesium alloy layer on one side of the midplate, the frame's boss is a magnesium alloy boss. Similarly, the magnesium alloy boss can be an integral structure with the magnesium alloy layer. That is, the magnesium alloy boss can be formed integrally with the magnesium alloy layer. By providing the magnesium alloy boss, the boss can overlap the end of the midplate, facilitating the connection between the frame and the midplate. When the boss is a magnesium alloy boss, the connection between the boss and the midplate can be welded, such as by spot welding or laser welding.

[0011] In an optional implementation, a plurality of mounting holes are provided at the end of the middle plate; the middle frame further comprises a plurality of positioning pins, one end of each positioning pin passes through one of the mounting holes and is welded to the boss, and the other end of each positioning pin is provided with a bolt cap. To facilitate welding, in one implementation, the material of the positioning pin can be the same as that of the boss. When the material of the boss is inconsistent with that of the middle plate and welding cannot be achieved, a fixed connection between the two can be achieved by providing a positioning pin. In addition, an end cap is provided at one end of the positioning pin, so that one end of the positioning pin can be fixed relative to the middle plate. The other end of the positioning pin passes through the mounting hole and is welded to the boss. In this way, the middle plate can be fixed by the positioning pin and the boss, thereby achieving the connection between the middle plate and the frame.

[0012] In one optional implementation, the boss is a titanium boss or a titanium alloy boss, and the locating pin is a titanium pin or a titanium alloy pin. When the boss is a titanium boss or a titanium alloy boss, the frame can be formed solely from the titanium layer or the titanium alloy layer. In this case, due to the high melting point of the titanium layer or the titanium alloy layer, it cannot be welded to other materials. Therefore, the locating pin is a titanium pin or a titanium alloy pin, which facilitates welding of the two, such as spot welding or laser welding.

[0013] In an optional implementation, the boss is provided with a plurality of mounting holes, and the end of the middle plate is provided with a plurality of bosses. The middle plate is mounted on the surface of the boss, and each of the bosses is inserted into one of the mounting holes. The middle plate and its bosses can be formed by casting. When the boss is a titanium boss or a titanium alloy boss, the entire frame can be a frame containing pure titanium metal. This frame has a high melting point, and the middle plate can be formed by casting. In this way, the bosses of the middle plate can be an integral structure with the body of the middle plate. After the bosses are inserted into the mounting holes of the bosses, the connection strength between the bosses and the bosses can be improved.

[0014] In one optional implementation, there are two bosses, spaced apart in the height direction of the middle frame. The end of the middle plate is positioned between the two bosses. Both sides of the end of the middle plate are provided with bosses, each of which is inserted into one of the mounting holes. The middle plate can be positioned between the two bosses to enhance the connection strength between the bosses and the middle plate. The middle plate and the bosses on its surface can also be cast.

[0015] In an optional implementation, the middle frame further includes a conductive sheet, one end of which is connected to the frame, and the other end of which is connected to the middle plate. Exemplarily, the conductive sheet may be a copper sheet. In some usage scenarios, the middle frame needs to serve as a signal transmission carrier for the antenna assembly. If there is a poor electrical connection between the frame and the middle plate, the antenna signal transmission stability will deteriorate. Therefore, a conductive sheet is provided between the frame and the middle plate, and the conductive sheet is used to achieve an effective electrical connection between the frame and the middle plate, so as to improve the reliability of the electrical connection between the two.

[0016] In one optional implementation, a boss is provided on the side of the frame facing the middle plate, a first notch is provided on the surface of the boss, and a second notch is provided on the surface of the middle plate where it connects to the boss. A portion of the conductive sheet is disposed within the first notch, and another portion of the conductive sheet is disposed within the second notch. Providing a notch for accommodating the conductive sheet improves the stability of the conductive sheet installation.

[0017] In the second aspect, the present application provides a middle frame, which includes a frame and a middle plate, the frame is arranged around the circumference of the middle plate and is connected to the middle plate, the frame includes an aluminum alloy layer and a magnesium alloy layer, the aluminum alloy layer is the appearance layer of the frame, the magnesium alloy layer is arranged toward the middle plate and is connected to the middle plate, and the middle plate is a magnesium alloy plate.

[0018] The middle frame of the present application comprises an aluminum alloy layer and a magnesium alloy layer. The aluminum alloy layer, as the outer layer of the frame, enhances the overall aesthetics of the middle frame and gives it an aluminum metallic texture. Furthermore, due to the high strength of the aluminum alloy layer, the aluminum alloy layer provides the frame with greater structural strength, drop resistance, shock resistance, and corrosion resistance, thereby improving the frame's strength and stability. The inner layer of the frame, i.e., the side facing the middle plate, comprises a magnesium alloy layer. Due to the low density of magnesium alloy, this helps reduce the weight of the frame. Furthermore, since the middle plate is often located inside an electronic device, using magnesium alloy plate does not affect the middle frame's appearance. Furthermore, magnesium alloy has a relatively low density and the middle plate has a relatively large area. Therefore, using magnesium alloy plate for the middle plate can help reduce the middle frame's overall weight. Thus, using a combination of aluminum alloy and magnesium alloy layers to form the frame and magnesium alloy plate to form the middle plate achieves the goal of reducing the middle frame's weight while improving its aesthetics and strength.

[0019] In a third aspect, the present application provides an electronic device comprising a display screen, a rear cover, an electronic device, and a middle frame of the present application. The middle frame is disposed between the display screen and the rear cover, and is connected to the display screen and the rear cover to form a storage space. The electronic device of the present application may be, for example, a mobile phone, a tablet computer, or the like.

[0020] The technical effects that can be achieved in the third aspect mentioned above can be described with reference to the corresponding effects in the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of a middle frame;

[0022] Figure 2 A simplified structural diagram of a middle frame in one embodiment;

[0023] Figure 3 This is a schematic diagram of the connection structure between the frame and the middle plate of an embodiment;

[0024] Figure 4 This is a schematic diagram of the connection structure between the frame and the middle plate of an embodiment;

[0025] Figure 5 A schematic diagram of a frame structure of an embodiment;

[0026] Figure 6 A schematic structural diagram of a frame according to another embodiment;

[0027] Figure 7 This is a schematic structural diagram of a middle frame in one embodiment;

[0028] Figure 8 This is a schematic structural diagram of a middle frame in another embodiment of the present application;

[0029] Figure 9 A schematic structural diagram of a composite plate formed of a titanium-containing metal layer, an aluminum alloy layer, and a magnesium alloy layer according to an embodiment;

[0030] Figure 10 A schematic diagram of a strip rolling process according to an embodiment;

[0031] Figure 11 Schematic diagram of the structure of a composite plate;

[0032] Figure 12 This is a schematic diagram of the process of processing the middle frame using composite panels;

[0033] Figure 13 This is a schematic diagram of the electrical connection between the frame and the middle plate of an embodiment;

[0034] Figure 14 The figure is a schematic structural diagram of a frame and a middle plate of an embodiment.

[0035] Reference numerals:

[0036] 100-middle frame; 10-border; 101-U-shaped frame; 102-straight frame; 103-antenna slot;

[0037] 11-titanium-containing metal layer; 12-aluminum alloy layer; 13-magnesium metal layer; 14-boss; 01-titanium-containing metal coil;

[0038] 02-aluminum foil; 03-magnesium alloy coil; 20-middle plate; 21-convex column; 30-mounting hole;

[0039] 40- positioning pin; 50- conductive sheet. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0041] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "above", "the", and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise.

[0042] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0043] In 3C products such as mobile phones, tablet computers and other terminal devices, the middle frame, as the main structural component, can provide dual functions of packaging and protection. Figure 1 This is a structural diagram of a middle frame. Figure 1As shown, the middle frame 100 may include a frame 10 and a middle plate 20, and the frame 10 is arranged around the periphery of the middle plate 20 and is connected to the middle plate 20. The frame 10 is arranged on the outside of the terminal device and can serve as the appearance surface of the terminal device. The middle plate 20 is arranged in the middle of the terminal device and can be used to carry electronic components such as chips, cameras, speakers, antennas, etc. Since the frame 10 part of the middle frame 100 needs to be arranged on the outside of the terminal device, the appearance surface of the frame 10 needs to maintain a high aesthetics and corrosion resistance, and at the same time needs to have a high strength to improve the drop resistance. The middle plate 20 is arranged inside the terminal device as a carrying substrate. Its appearance may not be a consideration standard, but it needs to have a certain strength to provide anti-drop and shock resistance. At the same time, it can also have a lower density to reduce the overall quality of the middle frame 100.

[0044] To meet the above requirements, an embodiment of the present application provides a middle frame. Figure 2 FIG. 1 is a simplified structural diagram of a middle frame in an embodiment. Figure 2 As shown, the middle frame 100 includes a frame 10 and a middle plate 20. The middle plate 20 is a plate-like structure, and the frame 10 is arranged along the circumferential edge of the middle plate 20 and is connected to the middle plate 20. In an electronic device, the middle plate 20 is arranged inside the electronic device, and the frame 10 forms the packaging side wall of the electronic device. The upper surface of the middle plate 20 can be used to assemble components such as a display screen, an earpiece, an antenna, a camera, a chip, and the like, and the display screen and the frame 10 can encapsulate the above-mentioned electronic components. Components such as a battery and a back cover can be installed on the lower part of the middle plate 20. The frame 10 and the back cover can encapsulate the battery. Figure 3 FIG. 1 is a schematic diagram of the connection structure between the frame 10 and the middle plate 20 according to an embodiment. Figure 3 As shown, in the embodiment of the present application, the frame 10 and the middle plate 20 are separate structures. The frame 10 and the middle plate 20 can be processed separately and then fixedly installed. To reduce the weight of the middle plate 20, the middle plate 20 can be formed of a magnesium alloy plate. The outer surface of the frame 10, which serves as the outer surface of the middle frame 100, can be made of a titanium-containing metal material. This improves the appearance and texture of the frame 10.

[0045] Continue to refer to Figure 2 In one embodiment, since the mobile phone requires an antenna, antenna slots 103 are provided in the sidewalls of the middle frame 100 to allow for antenna signal transmission. In this embodiment, the frame 10 can be divided into three sections along its length: a U-shaped frame 101 at each end and a straight frame 102 in the middle. Correspondingly, the middle plate 20 can also be segmented to match the segmentation of the frame 10. Assembly can be performed in sections.

[0046] Figure 44, in one embodiment, the frame 10 includes a titanium-containing metal layer 11, which can be used as the appearance layer of the frame 10 to provide the frame 10 with a titanium metal texture. The titanium-containing metal layer 11 can be a titanium layer or a titanium alloy layer. The titanium layer can be pure titanium metal and can include unavoidable impurities. The titanium alloy layer can have some other metal elements added to its material, such as aluminum and vanadium. Figure 4 The appearance surface of the titanium-containing metal layer 11 can be a curved surface. Figure 4 Taking the shown orientation as an example, a step surface can be provided on the upper and lower parts of the frame 10 respectively for assembly and connection with the display screen and the rear cover.

[0047] Although the titanium-containing metal layer 11 can improve the structural strength and metallic texture of the frame 10, the titanium-containing metal layer 11 cannot be welded to the magnesium alloy middle plate 20 due to the large difference in melting points between the titanium-containing metal and the magnesium alloy. Figure 4 As shown, a boss 14 may be provided on the side of the titanium-containing metal layer 11 facing the middle plate 20 , and the boss 14 and the titanium-containing metal layer 11 may be an integral structure. The boss 14 may be perpendicular to the titanium-containing metal layer 11 and parallel to the middle plate 20 .

[0048] by Figure 4 Taking the orientation shown as an example, the end of the middle plate 20 is arranged below the boss 14. The end of the middle plate 20 is provided with a mounting hole 30, and the mounting hole 30 is located below the boss 14. The number of mounting holes 30 can be multiple. In order to achieve the connection between the boss 14 and the middle plate 20, the middle frame 100 of the embodiment of the present application also includes positioning pins 40, and the number of positioning pins 40 can be multiple. A bolt cap is provided at one end of each positioning pin 40, and the radial dimension of the bolt cap is larger than the aperture of the mounting hole 30, so that the bolt cap can remain outside the mounting hole 30. As shown in FIG. Figure 4 As shown, the locating pin 40 is provided on one side of the bolt cap, and a recess can be machined at a relative position of the middle plate 20 to accommodate the bolt cap. The other end of each locating pin 40 can pass through one of the mounting holes 30 and be connected to the boss 14, such as by welding. In order to facilitate the welding of the boss 14 and the locating pin 40, the material of the locating pin 40 is the same as that of the boss 14. For example, when the boss 14 is a titanium-containing metal boss, that is, a titanium metal boss or a titanium alloy boss, the locating pin 40 can be a titanium metal pin or a titanium alloy pin. During welding, the connection between the boss 14 and the locating pin 40 can be achieved by spot welding or laser welding.

[0049] It is understandable that when the boss 14 is made of other materials, the locating pin 40 can also be made of the same material as the boss 14. The locating pin 40 can be a structural member such as a bolt or a rivet. The melting point difference between titanium metal or titanium alloy and magnesium alloy is close to 1000°C, making them difficult to weld together. The structure of the embodiment of the present application can use a combination of laser welding and riveting to achieve a mechanical fixed connection between the frame 10 and the middle plate 20, and the connection reliability is high. In addition, the frame 10 and the middle plate 20 can be surface treated separately during the manufacturing process.

[0050] Combined Figure 2 and Figure 4 The middle frame 100 of the embodiment of the present application can be obtained by the following preparation method:

[0051] S11. Material selection: The following brands of titanium metal materials can be selected: TA1, TA2, TA3, TA4, TC4, TC6, TC11, TC18, etc. Optional brands of magnesium alloy include but are not limited to: AZ31B, AZ91D, etc.

[0052] S12. The antenna seam of the frame 10 is used as a disconnection point to disassemble the components and form them separately. The forming technology can adopt one or more of the following processing technologies, such as bending, computerized numerical control (CNC), casting and metal powder injection molding (MIM) technology.

[0053] S13. The magnesium alloy middle plate 20 is formed by CNC or die-casting process, and its surface is treated by film or electrophoresis.

[0054] S14, nano injection molding: align and assemble the segmented frame 10, perform T-treatment and injection molding on the frame 10, and fill the antenna gap.

[0055] S15. Connect the titanium metal frame 10 and the magnesium alloy middle plate 20 under the positioning of a fixture, and the connection process adopts a combination of laser spot welding and riveting.

[0056] S16: Surface treatment is performed on the connected middle frame 100. Surface treatment processes include sandblasting, wire drawing, polishing, PVD, and anodizing.

[0057] The middle frame 100 obtained using the above method has a frame 10 partially made of titanium or a titanium alloy, and a middle plate 20 made of a magnesium alloy. The frame 10 and middle plate 20 are connected using lasers and rivets, a simple process that effectively solves the problem of connecting titanium or a titanium alloy to a magnesium alloy.

[0058] Frame 10 is entirely fabricated from titanium or a titanium alloy. Compared to frames 10 with a titanium-magnesium composite layered structure, this eliminates the need for a titanium-magnesium rolling process, reducing process complexity and costs. Furthermore, the segmented design of frame 10 during the aforementioned manufacturing process allows for separate nano-injection molding of the frame 10 after the components are assembled, thus preventing corrosion of the center plate 20 by the chemicals used during the T-treatment process.

[0059] Figure 5 This is a structural diagram of a frame of another embodiment of the present application. Figure 5 As shown, the frame 10 is made of titanium or titanium alloy. A boss 14 is also provided on the side of the frame 10 facing the middle plate 20. The boss 14 is an integral structure with the frame 10, that is, the boss 14 can be a boss made of titanium or titanium alloy. Figure 5 , a plurality of mounting holes 30 are provided on the boss 14, and the plurality of mounting holes 30 are arranged at intervals. Figure 5 Taking the shown orientation as an example, the end of the middle plate 20 can be placed above the boss 14 and connected to the boss 14. Among them, a boss 21 can be set on the side of the end of the middle plate 20 that is used to be placed with the boss 14, and the number of the bosses 21 can be multiple. Each boss 21 can be inserted into a mounting hole 30. The shape of the mounting hole 30 is not limited and can be a cylindrical hole, a square column hole, etc. Since the melting point of titanium metal and titanium alloy is much higher than that of magnesium alloy, after the frame 10 is assembled, the frame 10 can be placed in a casting mold by casting, and the middle plate 20 can be directly cast. This manufacturing method can directly form the middle column in the mounting hole 30 to form an interlocking structure to ensure the connection strength between the two.

[0060] Refer to Figure 2 and Figure 5 The method for preparing the middle frame of the embodiment of the present application may include the following steps:

[0061] S21. Material selection: The following brands of titanium metal materials can be selected: TA1, TA2, TA3, TA4, TC4, TC6, TC11, TC18, etc. Optional brands of magnesium alloy include but are not limited to: AZ31B, AZ91D, etc.

[0062] S22. The antenna seam of the frame 10 is used as a disconnection point to disassemble the components and form them separately. The forming technology can adopt one or more of bending, CNC, casting and MIM processes.

[0063] S23. Place the titanium metal or titanium alloy frame 10 into an injection molding mold, allowing the magnesium alloy casting liquid to fill the cavity enclosed by the frame 10. The casting liquid temperature is 650-750°C, and the mold temperature is 200-300°C. After the casting is completed, the middle plate 20 can be formed within the enclosed space of the frame 10. The protrusions on the surface of the middle plate 20 are formed in the mounting holes 30 of the bosses 14 of the frame 10, forming a self-locking structure.

[0064] S24, nano injection molding: After the above structural parts are subjected to T-treatment, they are subjected to injection molding treatment. The plastic wraps and fills the antenna seam and the joint seam between the frame 10 and the middle plate 20 to improve the bonding strength.

[0065] S25 , performing surface treatment on the middle frame 100 , wherein the surface treatment processes include: sandblasting, wire drawing, polishing, physical vapor deposition, and anodizing.

[0066] The preparation method of the above embodiment can eliminate the welding process between the boss and the middle plate, simplify the process, reduce processing costs, and improve bonding strength.

[0067] Among them, in the embodiment of the present application, since the frame and the middle plate are separate structures, the frame and the middle plate can be surface-treated separately during the processing process, or they can be surface-treated together after assembly, and no specific limitation is made here.

[0068] Figure 6 FIG. 1 is a structural diagram of a frame of another embodiment. Figure 6 As shown, relative to Figure 5 The difference between the frame structure shown is that in the frame 10 of this embodiment, the number of bosses 14 is two. The two bosses 14 are spaced apart in the height direction of the frame 10, that is, along the z direction shown in the figure. When assembling the middle plate 20, the end of the middle plate 20 can be installed between the two bosses 14. Both side surfaces of the end of the middle plate 20 are provided with bosses 21, and each boss 21 is inserted into a mounting hole 30. Similarly, the middle frame 100 of the embodiment of the present application can be processed by casting to connect the frame 10 and the middle plate 20. For the specific preparation method, please refer to Figure 5 The preparation method of the middle frame shown is not repeated here.

[0069] Figure 7 FIG. 1 is a schematic diagram of the structure of the middle frame of an embodiment. Figure 7 As shown, the frame 10 in this embodiment may include, in addition to the titanium-containing metal layer 11, an aluminum alloy layer 12. The aluminum alloy layer 12 is provided on the side of the frame 10 facing the middle plate 20. A boss 14 is provided on the side of the aluminum alloy layer 12 facing the middle plate 20. The boss 14 is an aluminum alloy boss 14, and the boss 14 is connected to the middle plate 20. The aluminum alloy boss can be directly welded to the magnesium alloy middle plate 20 or fixed by welding and riveting. For details, please refer to Figure 4 The structure shown.

[0070] Figure 8 This is a structural diagram of the middle frame of another embodiment of the present application. Figure 8 As shown, the frame 10 in this embodiment may include, in addition to the titanium-containing metal layer 11 and the aluminum alloy layer 12, a magnesium alloy layer 13. The magnesium alloy layer 13 is disposed on the surface of the aluminum alloy layer 12 facing the middle plate 20. That is, the aluminum alloy layer 12 is located between the titanium-containing metal layer 11 and the magnesium alloy layer 13. Due to the significant difference in melting points between the titanium-containing metal layer 11 and the magnesium alloy layer 13, hot pressing or welding cannot be achieved. By adding the aluminum alloy layer 12 between the two, the aluminum alloy layer 12 can serve as a transition layer to achieve a connection between the titanium layer and the magnesium metal layer. Similarly, a boss 14 is provided on the side of the magnesium alloy layer 13 facing the middle plate 20. The boss 14 is a magnesium alloy boss. The boss 14 can be perpendicular to the magnesium alloy layer 13. The middle plate 20 can be connected to the frame 10 by connecting with the boss 14. Since the connection between the magnesium alloy boss and the magnesium alloy middle plate 20 is simpler, such as welding, providing the magnesium alloy layer 13 on the outer surface of the aluminum alloy layer 12 is more conducive to achieving a fixed connection with the middle plate 20 by welding.

[0071] It should be noted that the overall thickness of the frame can be 3-10 mm, which can vary depending on the design of the frame. At the same position of the frame, whether the frame is provided with only one titanium-containing metal layer, a combination of a titanium-containing metal layer and an aluminum alloy layer, or a combination of a titanium-containing metal layer, an aluminum alloy layer, and a magnesium alloy layer, the thickness can be the same. Compared to a frame with a single titanium-containing metal layer, the addition of an aluminum alloy layer and a magnesium alloy layer can reduce the thickness of the titanium-containing metal layer without increasing the total thickness of the frame. Thus, the purpose of weight reduction and cost reduction can be achieved. Among them, when the frame is composed of a titanium-containing metal layer, an aluminum alloy layer, and a magnesium alloy layer, the aluminum alloy layer serves as a transition layer, and its thickness can be micron-level, so as to achieve the connection between the titanium-containing metal layer and the magnesium alloy layer.

[0072] in, Figure 9 FIG. 1 is a schematic structural diagram of a composite plate formed by a titanium metal layer, an aluminum alloy layer and a magnesium alloy layer according to an embodiment of the present invention. Figure 9 As shown, the composite plate can be formed by a hot pressing process. Exemplarily, the preparation method of the composite plate may include the following steps:

[0073] Step S1, Material Selection: Titanium or titanium alloy coils (i.e., titanium-containing metal coils 01) can be selected from the following grades: TA1, TA2, TA3, TA4, TC4, TC6, TC11, TC18, etc. Magnesium alloy coils 03 can be selected from grades including, but not limited to, AZ31B. Aluminum foil 02 can be selected from grades including 1060, 1100, 3003, 5052, 8011, 8021, 8079, etc. These coils are rolled into rectangular strips with a thickness of 1-5 mm for titanium, 5-10 mm for magnesium, and 0.01-0.05 mm for aluminum foil. All these materials have uniform cross-section widths ranging from 7-12 mm.

[0074] The width of each strip can be adjusted according to the height of the middle frame 100, with a processing allowance of about 1mm reserved on each side. Aluminum foil is used as an intermediate transition layer to enhance the bonding strength between titanium and magnesium.

[0075] Step S2, Texturing and Removing Oxide Film: Oxide films easily form on the surfaces of titanium, titanium alloys, magnesium alloys, and aluminum alloys. Oxide films have a high melting point and can hinder atomic diffusion at the interface between different metals. The surfaces of the titanium, titanium alloy, and magnesium alloy strips are mechanically polished to remove the oxide film and texturized. The surfaces are then cleaned with alcohol and dried. Aluminum foil is then soaked in a 6 mol / L NaOH solution, ultrasonically removed, and then cleaned with alcohol and dried. Acetone can also be used as an alternative to alcohol.

[0076] Step S3, rolling and laminating: the aluminum foil with the oxide film removed is sandwiched between the titanium or titanium alloy strip and the magnesium alloy strip, with the polished surfaces aligned and placed, and the starting ends are connected with rivets to facilitate entry into the rolling mill. Figure 10 Schematic diagram of a strip rolling process according to an embodiment. Figure 10 As shown, each strip is preheated at 400-450°C under Ar atmosphere protection for 10-20 minutes, and then sent to the rolling mill for rolling and compounding at a rolling speed of 0.1-0.5 m / s and a total deformation of about 50-70%.

[0077] Among them, before rolling, if the holding temperature is too low, the magnesium alloy strip will be cracked and the interface cannot be bonded; if the temperature is too high, the material will be too soft and cannot be bonded.

[0078] Step S4, heat treatment: the rolled composite material is kept in an Ar gas furnace at a temperature of 400°C ± 30°C for 30-60 minutes at normal pressure. Figure 11 This is a structural diagram of a composite board. Figure 11As shown, one side of the aluminum alloy layer 12 is a titanium-containing metal layer 11, i.e., a titanium layer or a titanium alloy layer, and the other side is a magnesium alloy layer 13. When the heat treatment temperature is too low and the time is too short, the atomic diffusion is not obvious and the interface bonding strength is low; when the heat treatment temperature is too high and the time is too long, continuous Ti3Al, Mg 17 Al 12 Brittle intermetallic compounds such as ferrites will reduce the interface bonding performance.

[0079] The above method can achieve a connection between titanium or titanium alloy and magnesium alloy. The main reasons are as follows: titanium alloys are mainly composed of titanium, aluminum, and vanadium, aluminum foil is mainly composed of aluminum, and magnesium alloys are mainly composed of magnesium, aluminum, and zinc. Under certain temperature and pressure, atoms undergo solid-state diffusion. The aluminum atoms in the three layers of material diffuse, penetrate, and interchange with each other. At the same time, the aluminum atoms in the middle layer form intermetallic compounds with titanium and magnesium, forming an atomic bond between the three layers. By controlling the temperature and time process, the formation of excessive brittle intermetallic compounds, which would deteriorate the bond strength, is avoided. The metal compounds are evenly dispersed on the bonding interface, achieving the effect of diffusion welding.

[0080] When manufacturing the middle frame, the composite board can be used to process the middle frame. Figure 12 This is a flow chart of using composite panels to process the middle frame. Figure 12 For example, the process of manufacturing the middle frame 100 using the composite plate may include the following steps:

[0081] Step S31, bending: Figure 9 The composite plate of the structure shown is cut into strip composite plates, and both ends of the strip composite plates are hot forged and bent 90 degrees to form a U-shaped frame 101, and a space for a straight frame 102 formed by the strip composite plates is reserved between the two oppositely arranged U-shaped frames 101.

[0082] Step S32 , CNC processing: CNC processing is performed on the U-shaped frame 101 and the strip-shaped composite plate, and a boss 14 for welding is processed on one side of the magnesium alloy layer 13 .

[0083] Step S33, welding: according to Figure 12 The structure shown is assembled with a U-shaped frame 101 and a strip composite plate, which are then fixed to the middle plate 20 using a jig and then welded. Welding techniques may include, but are not limited to, resistance welding, friction stir welding, and laser spot welding. An antenna gap is left between the U-shaped frame 101 and the strip composite plate.

[0084] Step S34, nano-injection molding: The welded structural parts are first subjected to T-treatment and then injection molding to obtain the middle frame 100. Plastic wraps and fills the weld seam and antenna seam to improve the bonding strength.

[0085] Step S35 : performing surface treatment on the middle frame 100 . The surface treatment process may include the following steps: sandblasting, wire drawing, polishing, physical vapor deposition, etc.

[0086] like Figure 12 As shown in the structure, an antenna slot needs to be reserved in the frame 10 to realize signal reception and transmission. In the traditional middle frame 100 structure, the frame 10 and the middle plate 20 are an integrated structure. When the antenna control unit is provided on the middle plate 20 and the antenna is provided on the frame 10, the middle frame 100 can be used as a signal transmission bridge. In the present application, since the frame 10 and the middle plate 20 are split structures, if the reliability of the electrical connection between the frame 10 and the middle plate 20 is reduced, it will affect the signal transmission between the antenna and the antenna control unit, causing the antenna signal to have frequency deviation or poor consistency. In order to achieve a stable electrical connection between the frame 10 and the middle plate 20, the reliability of the electrical connection between the frame 10 and the middle plate 20 can be improved by overlapping conductive sheets between the frame 10 and the middle plate 20, thereby improving the frequency deviation and poor consistency of the antenna.

[0087] Figure 13 FIG. 1 is a schematic diagram showing the electrical connection between the frame and the middle plate of an embodiment. Figure 13 As shown, in one embodiment, the middle frame 100 may further include a conductive sheet 50. One end of the conductive sheet 50 is connected to the frame 10, and the other end is connected to the middle plate 20. The conductive sheet 50 may be disposed at the junction of the frame 10 and the middle plate 20. In one embodiment, a notch may be provided on the surface of the boss 14 on the side of the frame 10 facing the middle plate 20, denoted as a first notch, and another notch may be provided on the surface of the middle plate 20 connected to the boss 14, denoted as a second notch. A portion of the conductive sheet 50 may be disposed within the first notch of the boss 14, and another portion of the conductive sheet 50 may be disposed within the second notch of the middle plate 20. In other words, when the first notch of the boss 14 and the second notch of the middle plate 20 are aligned, a groove may be formed to accommodate the conductive sheet 50. In one example, the groove may have dimensions of 4 mm × 2 mm, with a depth of 0.2 mm ± 0.05 mm. The conductive sheet 50 may have dimensions of 3.8 mm × 1.8 mm, and a thickness of 0.1 mm ± 0.02 mm. When installing the conductive sheet 50 , the conductive sheet 50 may be placed in the groove and then laser spot welded.

[0088] As described above, when microcracks exist in the connection interface between the frame 10 and the middle plate 20, by setting a conductive sheet 50 as a bridge, electrical connection between dissimilar metals can be achieved, thereby improving the reliability of the electrical connection between the frame 10 and the middle plate 20, improving the problems of antenna frequency deviation and low efficiency, and enhancing the consistency of the antenna.

[0089] Figure 14 This is a structural diagram of the middle frame of another embodiment of the present application. Figure 14As shown, the middle frame of this embodiment also includes a frame 10 and a middle plate 20. The frame 10 is arranged around the circumference of the middle plate 20 and is connected to the middle plate 20. The frame 10 includes an aluminum alloy layer 12 and a magnesium alloy layer 13, and the middle plate 20 is a magnesium alloy plate. The aluminum alloy layer 12 is the appearance layer of the frame, and the magnesium alloy layer 13 is arranged toward the middle plate and is connected to the middle plate 20. The aluminum alloy layer 12 and the magnesium alloy layer 13 in the frame 10 can be prepared by a pressing method, such as rolling and compounding aluminum foil and magnesium alloy coils. The connection method between the frame and the middle plate can be as follows Figures 3 to 7 The connection methods shown include, but are not limited to, welding, riveting, bolting, pressing, pinning, etc., which will not be repeated here.

[0090] Based on the same technical purpose, the present application also provides an electronic device. This electronic device can be, for example, a mobile terminal device such as a mobile phone, tablet computer, or watch. The electronic device may include a display screen, a rear cover, and a middle frame according to an embodiment of the present application. The display screen, rear cover, and middle frame may form a housing cavity, and electronic components of the electronic device, such as an earpiece, camera, chip, and battery, may be disposed within the housing cavity.

[0091] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A middle frame, characterized in that: It includes a frame and a middle plate, the frame is arranged around the circumference of the middle plate and is connected to the middle plate, the frame includes a titanium-containing metal layer, the titanium-containing metal layer is the appearance layer of the frame, and the titanium-containing metal layer is a titanium layer or a titanium alloy layer; the middle plate is a magnesium alloy plate.

2. The middle frame according to claim 1, characterized in that: An aluminum alloy layer is provided on the side of the titanium-containing metal layer facing the middle plate.

3. The middle frame according to claim 2, characterized in that: A magnesium alloy layer is provided on the side of the aluminum alloy layer facing the middle plate.

4. The middle frame according to any one of claims 1 to 3, characterized in that: A boss is provided on one side of the frame facing the middle plate, and the boss is connected to the middle plate.

5. The middle frame according to claim 4, characterized in that: The end of the middle plate is provided with a plurality of mounting holes; the middle frame further comprises a plurality of positioning pins, one end of each positioning pin passes through one of the mounting holes and is welded to the boss, and the other end of each positioning pin is provided with a bolt cap.

6. The middle frame according to claim 5, characterized in that: The material of the positioning pin is the same as that of the boss.

7. The middle frame according to claim 5, characterized in that: The boss is a titanium boss or a titanium alloy boss, and the positioning pin is a titanium pin or a titanium alloy pin.

8. The middle frame according to claim 4, characterized in that: The boss is provided with a plurality of mounting holes, and the end of the middle plate is provided with a plurality of bosses. The middle plate is placed on the surface of the boss, and each of the bosses is inserted into one of the mounting holes.

9. The middle frame according to claim 8, characterized in that: There are two bosses, which are arranged at intervals in the height direction of the middle frame. The end of the middle plate is arranged between the two bosses. Both side surfaces of the end of the middle plate are provided with bosses, and each boss is inserted into one of the mounting holes.

10. The middle frame according to any one of claims 1 to 3, characterized in that: The middle frame further includes a conductive sheet, one end of which is connected to the frame, and the other end of which is connected to the middle plate.

11. The middle frame according to claim 10, characterized in that: The conductive sheet is a copper sheet.

12. The middle frame according to claim 10, characterized in that: A boss is provided on the side of the frame facing the middle plate, a first notch is provided on the surface of the boss, and a second notch is provided on the surface of the middle plate connected to the boss; a portion of the conductive sheet is provided in the first notch, and another portion of the conductive sheet is provided in the second notch.

13. A middle frame, characterized in that: It includes a frame and a middle plate, the frame is arranged around the circumference of the middle plate and is connected to the middle plate, the frame includes an aluminum alloy layer and a magnesium alloy layer, the aluminum alloy layer is the appearance layer of the frame, the magnesium alloy layer is arranged toward the middle plate and is connected to the middle plate, and the middle plate is a magnesium alloy plate.

14. An electronic device, characterized in that: It includes a display screen, a back cover, an electronic device and a middle frame as described in any one of claims 1 to 13, wherein the middle frame is arranged between the display screen and the back cover, and is respectively connected to the display screen and the back cover to form a storage space, and the electronic device is arranged in the storage space.

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