Middle frame, preparation method thereof and electronic equipment

Abstract

The embodiment of the invention provides a middle frame, a preparation method thereof and electronic equipment, relates to the field of electronic equipment, and is used for realizing reliable connection between a middle plate and an outer frame, improving the impact resistance of the middle frame and guaranteeing the consistency of radio frequency performance of a frame antenna of the electronic equipment. The middle frame comprises a middle plate, an outer frame and a connecting piece. The middle plate comprises a mounting hole. The outer frame is located outside the middle plate. The outer frame comprises a main body part and an extension part which are connected, and the extension part and the middle plate are stacked. The connecting piece is located in the mounting hole and connected with the middle plate. The connecting piece is welded with the extension part. Wherein the material of the middle plate comprises one of magnesium alloy, a magnesium-based composite material and aluminum alloy. The outer frame is made of one of aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material. And the microhardness of the connecting piece is greater than that of the middle plate. The middle frame is applied to the electronic equipment so as to improve the performance of the electronic equipment.

Description

Technical Field

[0001] The present application relates to the field of electronic equipment, and in particular to a middle frame and a preparation method thereof, and electronic equipment. Background Art

[0002] The middle frame is one of the important hardware of electronic devices, which is used to carry important components such as the motherboard and battery of the electronic device. At the same time, the display screen and back cover of the electronic device also need to be fixed on the middle frame. The structure of the middle frame has a great impact on the production cost and weight of the electronic device.

[0003] At present, the middle frame generally includes a middle plate and an outer frame, the material of the middle plate includes magnesium alloy, magnesium-based composite material or aluminum alloy, and the material of the outer frame includes aluminum, titanium, steel, etc. The middle plate and the outer frame are connected by welding. However, when the material of the middle plate includes magnesium alloy or magnesium-based composite material, due to the disadvantages of magnesium alloy or magnesium-based composite material such as low melting point and easy evaporation, high activity and easy oxidation, when the middle plate and the outer frame are directly welded, welding defects are prone to occur at the welding point between the middle plate and the outer frame. When the material of the middle plate includes aluminum alloy, the middle plate is usually prepared by die casting. However, a large number of pores are prone to appear inside the middle plate prepared by die casting, so when the middle plate and the outer frame are directly welded, welding defects are also prone to occur at the welding point between the middle plate and the outer frame. The presence of welding defects will make the stability of the solder joints poor, resulting in reduced impact resistance of the middle frame.

[0004] At the same time, with the rapid development of communication technology, electronic devices are generally equipped with antennas for communication to achieve functions such as making calls and surfing the Internet. As a good radiator, the middle frame can be used as an antenna, effectively reducing the space occupied by the built-in antenna in the electronic device. The presence of welding defects between the middle plate and the outer frame will also lead to poor consistency in the impedance value of the solder joint, affecting the consistency of the RF performance of the frame antenna of the electronic device. Summary of the invention

[0005] The embodiments of the present application provide a middle frame and a preparation method thereof, and an electronic device, which are used to achieve reliable connection between a middle plate and an outer frame, improve the impact resistance of the middle frame, and ensure the consistency of the radio frequency performance of the frame antenna of the electronic device.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, a middle frame is provided, which includes a middle plate, an outer frame and a connecting piece. The middle plate includes a mounting hole. The outer frame is located on the outer side of the middle plate. The outer frame includes a main body and an extension portion connected to each other, the extension portion is located on the side of the main body facing the middle plate, and the thickness of the extension portion is less than the thickness of the main body portion. The extension portion is stacked with the middle plate. The connecting piece is located in the mounting hole and connected to the middle plate. The connecting piece is welded to the extension portion. Among them, the material of the middle plate includes one of a magnesium alloy, a magnesium-based composite material and an aluminum alloy; the material of the outer frame includes one of an aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material; the microhardness of the connecting piece is greater than the microhardness of the middle plate.

[0008] In the embodiment of the present application, the connecting piece is placed in the mounting hole of the middle plate, so that the connecting piece is connected to the middle plate, and the connecting piece is welded to the outer frame, so that the middle plate and the outer frame are fixed to each other to form a middle frame. Among them, when the material of the middle plate includes magnesium alloy and / or magnesium-based composite material, since the density of magnesium alloy and magnesium-based composite material is relatively small, the weight of the middle plate can be smaller, and the weight of the middle frame can be smaller, which is beneficial to reduce the weight of the electronic equipment using the middle frame. In the case where the material of the middle plate includes aluminum alloy, the middle plate can be prepared by a die-casting process. In this way, compared with the method of preparing the middle plate by CNC machine tool processing, the preparation cost of the middle plate can be lower, and the production efficiency of the middle plate can be higher, which is beneficial to realize mechanical automation production.

[0009] In an embodiment of the present application, the material of the outer frame includes one of aluminum alloy, titanium-based material, iron-based material, titanium-aluminum composite material and steel-aluminum composite material, so that the appearance area of ​​the middle frame can have a metallic texture, which is beneficial to improving the competitiveness of electronic equipment using the middle frame.

[0010] In the embodiment of the present application, a connecting piece is used to connect the middle plate and the outer frame. The microhardness of the connecting piece is greater than the microhardness of the middle plate, which effectively improves the problem of welding defects at the welding position between the middle plate and the outer frame due to the low melting point and easy evaporation of magnesium alloy or magnesium-based composite materials, high activity and easy oxidation, or the presence of a large number of pores in the die-cast aluminum material when the middle plate and the outer frame are directly welded together. This makes the connection reliability between the middle plate and the outer frame higher, which is beneficial to improving the stability of the middle frame and improving the impact resistance of the middle frame.

[0011] The middle frame is a good radiator and can be used as an antenna. In the middle frame provided in the embodiment of the present application, the middle plate is connected to the connector, and the outer frame is also welded to the connector. The connection between the middle plate and the outer frame is not prone to welding defects, which is conducive to ensuring the consistency of the impedance value at the connection between the middle plate and the outer frame, and further ensuring the consistency of the RF performance of the frame antenna in the electronic device.

[0012] At the same time, in the middle frame provided in the embodiment of the present application, the outer frame and the connecting piece are connected by welding. Compared with the case where the middle plate and the outer frame are directly connected by rivets, the stress at the connection position between the connecting piece and the outer frame can be smaller, and the stress at the connection position between the middle plate and the outer frame can be smaller, so that the middle frame is not easy to be twisted and deformed, and the flatness of the middle frame is effectively improved. Compared with the case where the middle plate and the outer frame are connected by riveting without rivets, the thickness of the connection between the middle plate and the outer frame provided in the embodiment of the present application can be smaller, which is conducive to reducing the thickness of the middle frame, reducing the thickness of the electronic device using the middle frame, and realizing ultra-thin electronic devices.

[0013] In some embodiments, the connecting member includes a first connecting portion and a second connecting portion that are perpendicular to each other, the first connecting portion is located in the mounting hole and welded to the extension portion, and a portion of the middle plate is located between the second connecting portion and the extension portion.

[0014] In this way, on the one hand, the middle plate is confined between the second connection part of the connector and the extension part of the outer frame. In the thickness direction of the middle plate and in the direction parallel to the middle plate, relative displacement between the middle plate and the connector is not easy to occur, and the middle plate and the connector are not easy to separate. On the other hand, the first connection part and the second connection part of the connector are in contact with the middle plate, which can also increase the contact area between the middle plate and the connector. The connection stability between the middle plate, the outer frame and the connector can be good, which is conducive to further improving the yield of the middle frame and improving the stability of the use of the middle frame.

[0015] In some embodiments, the mounting hole is a stepped hole, and the first connecting portion and the second connecting portion are both located in the stepped hole; the end surface of the second connecting portion away from the first connecting portion is flush with the surface of the middle plate away from the extension portion.

[0016] At this time, the end surface of the second connection part away from the first connection part is flush with the surface of the middle plate away from the extension part. This can make the middle frame more flat, so that the middle frame can better carry electronic components or display screens, and improve the yield of electronic equipment using the middle frame.

[0017] In some embodiments, the connecting piece is a column, and the connecting piece and the mounting hole are interference-fitted. In this way, the connecting piece has a simple structure and is easy to obtain, which is conducive to simplifying the structure of the middle frame.

[0018] In some embodiments, the material of the connector is the same as that of the outer frame. In this way, the melting point of the connector and the outer frame can be the same, and when welding the connector and the outer frame, it is not easy to affect the yield of the welding point of the connector and the outer frame due to the large difference in the melting point of the connector and the outer frame, which is conducive to further improving the connection strength of the connector and the outer frame and improving the connection stability of the connector and the outer frame.

[0019] In some embodiments, the mounting holes include through holes or blind holes.

[0020] In some embodiments, the extension portion includes a first part and a second part, the second part is arranged around the first part, the first part and the connecting piece have a molten pool, and the molten pool extends from the surface of the first part away from the middle plate to the connecting piece; or, the molten pool extends from the surface of the connecting piece away from the extension portion to the first part.

[0021] In some embodiments, the main body includes a first surface and a second surface relative to each other, and a first side surface and a second side surface connecting the first surface and the second surface, the first surface is farther away from the extension portion than the second surface, and the second surface is connected to the extension portion; the middle frame also includes a decorative layer, and the decorative layer at least covers the first surface.

[0022] The embodiment of the present application provides a decorative layer, which can, on the one hand, color the surface of the outer frame, improve the appearance of the outer frame, and increase users' preference for the electronic device; on the other hand, the decorative layer can also be used to protect the outer frame to prevent the outer frame from being corroded by water vapor and oxygen in the environment.

[0023] In some embodiments, the molten pool extends from the surface of the first portion away from the middle plate to the connector, and the decorative layer also covers the surface of the second portion away from the middle plate, the first side surface, the second side surface, and the portion of the second surface not in contact with the extension portion. When the molten pool extends from the surface of the first portion away from the middle plate to the connector, the decorative layer exposes the surface of the first portion away from the connector and the surface of the first portion close to the connector, which helps to avoid affecting the welding yield due to the high melting point of the decorative layer.

[0024] In some embodiments, the molten pool extends from the surface of the connector away from the extension portion into the first portion; the decorative layer also covers the surface of the first portion away from the middle plate, the surface of the second portion away from the middle plate, the first side surface, the second side surface, and the portion of the second surface that is not in contact with the extension portion.

[0025] When the molten pool extends from the surface of the connector away from the extension portion into the first portion, the decorative layer exposes the surface of the first portion close to the connector, which helps to avoid affecting the welding yield due to the high melting point of the decorative layer.

[0026] In some embodiments, the shear strength of the weld between the extension and the connector is greater than or equal to 100 N, and the pull strength of the weld between the extension and the connector is greater than or equal to 90 N. In this way, the connection stability between the extension and the connector is better, the connection stability between the outer frame and the middle plate and the connector is better, the stability of the middle frame can be higher, and the impact resistance of the middle frame can also be better, which is conducive to improving the service life of the electronic device.

[0027] In some embodiments, the material of the outer frame includes a titanium-aluminum composite material, the main body includes a first sublayer and a second sublayer, the first sublayer is farther away from the extension part than the second sublayer, the second sublayer is connected to the extension part, the material of the first sublayer includes titanium, and the material of the second sublayer and the material of the extension part both include aluminum alloy.

[0028] In the outer frame provided in the embodiment of the present application, the material of the first sublayer of the main body is set to titanium metal, the material of the second sublayer is set to aluminum alloy, and the material of the extension part is set to aluminum alloy. The density of the aluminum alloy is lower than that of the titanium metal. As a result, the middle frame can have a metallic texture and appearance while having a smaller weight, which is beneficial to reducing the preparation cost of the middle frame.

[0029] Alternatively, the material of the outer frame includes a steel-aluminum composite material, the main body includes a third sublayer and a fourth sublayer, the third sublayer is farther away from the extension part than the fourth sublayer, the fourth sublayer is connected to the extension part, the material of the third sublayer includes stainless steel, and the material of the fourth sublayer and the material of the extension part both include aluminum alloy.

[0030] In the outer frame provided in the embodiment of the present application, the material of the first sublayer of the main body is set to stainless steel, the material of the second sublayer is set to aluminum alloy, and the material of the extension part is set to aluminum alloy. The density of aluminum alloy is lower than that of stainless steel, so that the middle frame can have a metallic texture and appearance while having a smaller weight, which is beneficial to reducing the preparation cost of the middle frame.

[0031] In a second aspect, a method for preparing a middle frame is provided. The preparation method includes: providing a middle plate, an outer frame and a connector. The outer frame includes a main body and an extension portion that are connected to each other, and the thickness of the extension portion is less than the thickness of the main body portion. The connector is installed on the middle plate; the connector is located in the mounting hole of the middle plate. The middle plate and the outer frame are fixed; the outer frame is located on the outer side of the middle plate, the extension portion is located on the side of the main body facing the middle plate, and the extension portion is stacked with the middle plate. The extension portion is welded to the connector. Among them, the material of the middle plate includes one of a magnesium alloy, a magnesium-based composite material and an aluminum alloy, and the material of the outer frame includes one of an aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material; the microhardness of the connector is greater than the microhardness of the middle plate.

[0032] In some embodiments, welding the extension portion to the connection piece includes: welding the extension portion to the connection piece using a laser welding process.

[0033] In the embodiment of the present application, the laser welding process is used to weld the extension part and the connecting part, the welding precision can be high, the deformation of the extension part and the connecting part can be small, the stress between the extension part and the connecting part can be small, and after the extension part and the connecting part are welded, the middle frame is not easy to deform, which is conducive to improving the flatness of the middle frame. At the same time, the laser welding has a high welding speed. Using the laser welding process to weld the extension part and the connecting part is also conducive to improving the preparation speed of the middle frame and improving the preparation efficiency of the middle frame.

[0034] In some embodiments, the material of the outer frame includes aluminum alloy, and the preparation method further includes: forming a decorative layer by an anodizing process; or, the material of the outer frame includes one of a titanium-based material, an iron-based material, a titanium-aluminum composite material, and a steel-aluminum composite material, and the preparation method further includes: forming a decorative layer by a physical vapor deposition process.

[0035] The main body includes a first surface and a second surface relative to each other, and a first side surface and a second side surface connecting the first surface and the second surface. The first surface is farther away from the middle plate than the second surface, and the second surface is connected to the extension portion. The decorative layer at least covers the first surface.

[0036] In a third aspect, an electronic device is provided, comprising a display screen and a rear shell, and a middle frame as described in any of the above embodiments, wherein the middle frame is located between the display screen and the rear shell; and an outer frame of the middle frame serves as a side of the electronic device.

[0037] Among them, the technical effects brought about by any design method in the second aspect to the third aspect can refer to the technical effects brought about by different design methods in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the present application, the following is a brief introduction to the drawings required for use in some embodiments of the present application. Obviously, the drawings described below are only drawings of some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not intended to limit the actual size of the product involved in the embodiments of the present application, the actual process of the method, the actual timing of the signal, etc.

[0039] Figure 1 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of the structure of a middle frame provided in an embodiment of the present application;

[0041] Figure 3 A schematic top view of a middle frame provided in an embodiment of the present application;

[0042] Figure 4 for Figure 3 The middle frame shown is an enlarged schematic diagram at AA;

[0043] Figure 5 for Figure 3 A schematic cross-sectional view of the middle frame at BB' shown;

[0044] Fig. 6A for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0045] Figure 6B for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0046] Figure 6C for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0047] Fig. 7A for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0048] Figure 7B for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0049] Figure 8 for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0050] Fig. 9A for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0051] Fig. 9B for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0052] Fig.10 A physical diagram of the connection between a connecting member and an extension portion provided in an embodiment of the present application;

[0053] Fig.11 An element detection diagram of the connection between the connector and the extension portion provided in an embodiment of the present application;

[0054] Fig.12 A physical diagram of the connection between another connecting member and the extension portion provided in an embodiment of the present application;

[0055] Fig.13 for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0056] Fig.14 for Figure 3 Another cross-sectional schematic diagram of the middle frame shown at BB';

[0057] Fig.15 A flow chart of a method for preparing a middle frame provided in an embodiment of the present application;

[0058] Fig.16 A flow chart of another method for preparing a middle frame provided in an embodiment of the present application;

[0059] Fig.17 for Fig.16 A state diagram corresponding to step S410 in the flowchart shown;

[0060] Fig.18 for Fig.16 Another state diagram corresponding to step S410 in the flowchart shown;

[0061] Fig.19 A flow chart of another method for preparing a middle frame provided in an embodiment of the present application;

[0062] Fig. 20 A flow chart of another method for preparing a middle frame provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] The technical solution in the embodiment of the present application will be described below in conjunction with the accompanying drawings in the embodiment of the present application. In the description of the present application, unless otherwise specified, " / " indicates that the objects associated before and after are in an "or" relationship, for example, A / B can represent A or B.

[0064] The "and / or" in this application is only a way to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.

[0065] In the description of this application, unless otherwise specified, "plurality" means two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can mean: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, and c can be single or multiple.

[0066] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with substantially the same functions and effects. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit the difference.

[0067] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0068] The embodiment of the present application provides an electronic device, which is, for example, a consumer electronic product, a home electronic product, a vehicle-mounted electronic product, a financial terminal product, and a communication electronic product. Among them, consumer electronic products are such as mobile phones, tablet computers (pad), laptop computers, e-readers, personal computers (PC), personal digital assistants (PDA), desktop displays, smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) electronic devices, augmented reality (AR) electronic devices, drones, etc. Home electronic products are such as smart door locks, televisions, remote controls, refrigerators, rechargeable small household appliances (e.g., soybean milk machines, sweeping robots), etc. Vehicle-mounted electronic products are such as vehicle-mounted navigation systems, vehicle-mounted high-density digital video discs (DVD), etc. Financial terminal products are such as automated teller machines (ATMs), self-service terminals, etc. The embodiment of the present application does not impose any special restrictions on the specific form of the electronic device.

[0069] For the convenience of explanation, the following description takes the electronic device as a tablet computer as an example. Figure 1 As shown, the electronic device 100 mainly includes a display screen 10, a middle frame 20 and a rear shell 30. The middle frame 20 is located between the display screen 10 and the rear shell 30. The display surface of the display screen 10 is away from the middle frame 20.

[0070] Exemplarily, the display screen 10 may be a liquid crystal display (LCD). In this case, the LCD screen includes a liquid crystal display panel and a backlight module. The liquid crystal display panel is arranged on a side of the backlight module away from the middle frame. The backlight module is used to provide a light source for the liquid crystal display panel.

[0071] Alternatively, the display screen 10 may also be an organic light emitting diode (OLED) display screen. Since the OLED display screen is a self-luminous display screen, there is no need to set a backlight module. In this case, the display screen 10 may also be a flexible screen with bending performance, that is, a folding screen, or a rigid display screen.

[0072] The electronic device 100 may further include electronic components such as printed circuit boards (PCB), batteries, and cameras, and the printed circuit boards, batteries, and cameras may be disposed on the middle frame 20. For example, the printed circuit board (mainboard), batteries, cameras, and other electronic components may be located on a side of the middle frame 20 away from the display screen 10.

[0073] As an important component of the electronic device 100, the printed circuit board can be mounted with various devices constituting the circuit system of the electronic device, such as circuits, processors, chips, capacitors, resistors, inductors, structures and plug-ins, etc. Optionally, the printed circuit board can be provided with an integrated circuit chip, a power management unit chip or a radio frequency chip, etc. In addition, the printed circuit board is also generally provided with various processors such as a central processing unit, various application processors, a graphics processor or an image signal processor, but is not limited thereto.

[0074] The battery is used as an energy storage tool for the electronic device 100 and can be a lithium battery, a nickel-hydrogen battery, a sodium-ion battery, etc.

[0075] The camera may include components such as a front camera, a rear camera, and a flash.

[0076] The rear shell 30 can protect the electronic components in the electronic device 100 and prevent water vapor and / or dust from affecting the normal operation of the electronic components. At the same time, the rear shell 30 can also ensure the neat appearance of the electronic device. In the embodiment of the present application, there is no limitation on the material of the rear shell 30. For example, the material of the rear shell 30 can be a conductive material such as metal. For another example, the material of the rear shell 30 can be a non-conductive material such as glass and plastic. When the material of the rear shell 30 is a conductive material, the rear shell 30 can be used as a reference ground for electronic components or radio frequency devices in the electronic device 300.

[0077] In some examples, the electronic device 100 may further include a cover plate, which is disposed on a side of the display screen 10 away from the middle frame 20 to protect the display screen 10 .

[0078] When the electronic device 100 is a mobile phone, the electronic device 100 may be a foldable mobile phone or a straight-screen mobile phone, which is not limited in the present application.

[0079] Below, refer to Figures 2 to 14 , the middle frame 20 provided in the embodiment of the present application is described in detail.

[0080] Figure 2 This is an exploded view of the middle frame 20 provided in the embodiment of the present application. Figure 3 This is a schematic top view of the middle frame 20 provided in an embodiment of the present application. Figure 4 for Figure 3 The structure of the middle frame 20 at position AA is shown in an enlarged view. Figure 5 for Figure 3 A schematic cross-sectional view of the middle frame 20 at BB′ is shown. Fig. 6A for Figure 3 Another cross-sectional schematic diagram of the middle frame 20 at the BB' line is shown. Figure 2 to Figure 6A , the present application embodiment provides a middle frame 20. Figure 2 As shown, the middle frame 20 includes a middle plate 1 , an outer frame 2 and a connecting member 3 .

[0081] The middle plate 1 includes a mounting hole 11. Exemplarily, the middle plate 1 may include a plurality of mounting holes 11, and the plurality of mounting holes 11 are distributed on the edge of the middle plate 1.

[0082] When the middle plate 1 includes a plurality of mounting holes 11, the sizes of the plurality of mounting holes 11 may be the same or different. The "different sizes of the plurality of mounting holes 11" mentioned here means that there is at least one mounting hole 11 among the plurality of mounting holes 11, and the size of the mounting hole 11 is different from the sizes of the remaining mounting holes 11. In the embodiment of the present application, there is no restriction on the specific number and size of the mounting holes 11 in the middle plate 1, and the design may be performed according to actual needs.

[0083] The distribution position of the mounting holes 11 in the embodiment of the present application is also not limited. The specific distribution position of the mounting holes 11 can be designed according to the structure of the middle plate 1 and the structure of the outer frame 2 so that the middle plate 1 and the outer frame 2 are stably connected. Figure 4 As shown, at the corners of the middle plate 1 , the distribution density of the mounting holes 11 may be relatively large, and on the sides of the middle plate 1 , the distribution density of the mounting holes 11 may be relatively small.

[0084] The material of the middle plate 1 may include one of a magnesium alloy, a magnesium-based composite material and an aluminum alloy. For example, the magnesium alloy may be AZ91D, AM60, AZ31, AZ80, AZ91D or ZK61.

[0085] like Figure 3 As shown, the outer frame 2 is located outside the middle plate 1. Figure 2 and Figure 3 The outer frame 2 can serve as the side of the electronic device 100.

[0086] See also Figure 5 The outer frame 2 includes a main body 21 and an extension 22 connected to each other. The extension 22 is located on the side of the main body 21 facing the middle plate 1, and the thickness d1 of the extension 22 is less than the thickness d2 of the main body 21. The extension 22 is stacked with the middle plate 1. In the embodiment of the present application, the specific values ​​of the thickness d1 of the extension 22 and the thickness d2 of the main body 21 are not limited and can be designed according to actual needs.

[0087] In some examples, such as Figure 5 As shown, the sum of the thickness d3 of the portion of the middle plate 1 in contact with the extension 22 and the thickness d1 of the extension is less than the thickness d2 of the main body 21 of the outer frame 2. In this way, the sum of the thickness d3 of the portion of the middle plate 1 in contact with the extension 22 and the thickness d1 of the extension can be smaller, which is conducive to reducing the thickness of the middle frame 20. At the same time, the sum of the thickness d3 of the portion of the middle plate 1 in contact with the extension 22 and the thickness d1 of the extension can be smaller, and electronic components can be arranged at the stacking position of the middle plate 1 and the extension 22, thereby improving the space utilization rate at the stacking position of the middle plate 1 and the extension 22.

[0088] In some examples, such as Figure 5 As shown, the main body 21 and the extension 22 can be an integral structure. In this case, the main body 21 and the extension 22 are not easy to separate, and the connection stability between the main body 21 and the extension 22 can be relatively high, which is beneficial to improve the structural stability of the outer frame 2, and further improve the structural stability of the middle frame 20.

[0089] In other examples, such as Fig. 6A As shown, the main body 21 and the extension 22 can be connected by welding. In this way, the main body 21 and the extension 22 provided in the embodiment of the present application can be prepared separately, and the size of the raw materials used in the preparation process of the main body 21 and the extension 22 can be smaller, which is conducive to reducing the preparation cost of the outer frame 2, and further reducing the preparation cost of the middle frame 20.

[0090] At this time, if Fig. 6A As shown, a molten pool U may be present in a portion of the main body 21 that contacts the extension portion 22 , and in a portion of the extension portion 22 that contacts the main body 21 .

[0091] For example, the main body 21 and the extension portion 22 may be welded by spot welding or seam welding.

[0092] In some examples, such as Figure 2 As shown, the outer frame 2 may include a plurality of frame bars 201. For example, the outer frame 2 may include two frame bars 201, and the two frame bars 201 may be located on opposite sides of the middle plate 1, respectively. Alternatively, the outer frame 2 may include three frame bars, and the three frame bars are connected end to end to form a roughly U-shaped structure. In this case, the middle frame 20 may be applied to a foldable electronic device. Alternatively, the outer frame 2 may include four frame bars 201, and the four frame bars 201 are connected end to end in sequence to form a closed structure, and the outer frame 2 may be arranged around the middle plate 1. Each frame bar 201 may include the above-mentioned main body 21 and extension 22.

[0093] The material of the outer frame 2 may include one of an aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material, and a steel-aluminum composite material. For example, the aluminum alloy may include a five-series aluminum alloy, a six-series aluminum alloy, or a seven-series aluminum alloy. The titanium-based material may include, for example, titanium and a titanium alloy. The iron-based material may include, for example, stainless steel.

[0094] In some examples, stainless steel is stainless steel as defined in GB / T20878-2007, and its chromium content is at least 10.5%, and its carbon content is no more than 1.2%. In the embodiment where the material of the outer frame 2 is stainless steel, there is no restriction on the type of stainless steel, and the type of stainless steel may be, for example, SUS316L. Stainless steel has the advantages of high elastic modulus and high strength. The outer frame 2 made of stainless steel can provide excellent supporting performance for the structure of the electronic device 100 (such as a display screen, a cover plate), etc., and provides a basis for the outer frame 2 that is thin and has excellent strength.

[0095] In the embodiment where the material of the outer frame 2 is titanium alloy, there is no limitation on the type of titanium alloy, for example, the type of titanium alloy may be TC4. Similarly, titanium alloy also has the advantages of high elastic modulus and high strength, and the outer frame 2 made of titanium alloy can have the advantages of both lightness and high strength.

[0096] The connector 3 is located in the mounting hole 11 and connected to the middle plate 1. The connector 3 is welded to the extension portion 22. The microhardness of the connector 3 is greater than the microhardness of the middle plate 1. Exemplarily, the material of the connector 3 may include one of an aluminum-based material, a titanium-based material, an iron-based material, a copper-based material, a nickel-based material, and a zirconium-based material. It is understood that the connector 3 is located in the mounting hole 11, and the number of the connectors 3 should be the same as the number of the mounting holes 11.

[0097] In the embodiment of the present application, the connector 3 is placed in the mounting hole 11 of the middle plate 1, so that the connector 3 is connected to the middle plate 1, and the connector 3 is welded to the outer frame 2, so that the middle plate 1 is fixed to the outer frame 2 to form the middle frame 20. Among them, when the material of the middle plate 1 includes magnesium alloy and / or magnesium-based composite material, since the density of magnesium alloy and magnesium-based composite material is small, the weight of the middle plate 1 can be small, and the weight of the middle frame 20 can be small, which is conducive to reducing the weight of the electronic device 100 using the middle frame 20. In the case where the material of the middle plate 1 includes aluminum alloy, the middle plate 1 can be prepared by a die-casting process. In this way, compared with the method of preparing the middle plate by using CNC machine tools (Computer numerical control machine tools, CNC), the preparation cost of the middle plate 1 can be lower, and the production efficiency of the middle plate 1 can be higher, which is conducive to realizing mechanical automation production.

[0098] In the embodiment of the present application, the material of the outer frame 2 includes one of aluminum alloy, titanium-based material, iron-based material, titanium-aluminum composite material and steel-aluminum composite material, so that the appearance area of ​​the middle frame 20 can have a metallic texture, which is beneficial to improving the competitiveness of the electronic device 100 using the middle frame 20.

[0099] In the embodiment of the present application, the middle plate 1 and the outer frame 2 are connected by a connecting member 3, and the microhardness of the connecting member 3 is greater than the microhardness of the middle plate 1, which effectively improves the problem of welding defects at the welding position between the middle plate and the outer frame due to the low melting point and easy evaporation of magnesium alloy or magnesium-based composite materials, high activity and easy oxidation, or the presence of a large number of pores in the die-cast aluminum material when the middle plate and the outer frame are directly welded together. This makes the connection reliability between the middle plate 1 and the outer frame 2 higher, which is beneficial to improving the stability of the middle frame 20 and improving the impact resistance of the middle frame 20.

[0100] The middle frame 20 is a good radiator and can be used as an antenna. In the middle frame 20 provided in the embodiment of the present application, the middle plate 1 is connected to the connector 3, and the outer frame 2 is welded to the connector 3. The connection between the middle plate 1 and the outer frame 2 is not prone to welding defects, which is conducive to ensuring the consistency of the impedance value at the connection between the middle plate 1 and the outer frame 2, and further ensuring the consistency of the RF performance of the frame antenna in the electronic device 100.

[0101] The embodiment of the present application tests the impedance value at the position where the connector 3 is located in the middle frame 20. The test equipment is a resistance tester, and the test results are shown in Table 1. It can be seen from Table 1 that at the position where the connector 3 is located, the impedance measured at each test point is small, and the difference between the impedances measured at different test points is also small, and good metal conduction can be achieved between the middle plate 1 of the middle frame 20 and the outer frame 2. In this way, when the middle frame 20 is used as an antenna, it can not only work in low frequency bands such as 2.4GHz, but also in high frequency bands such as 5GHz. In particular, when the middle frame 20 is used as an antenna such as a 4GHz band antenna, a 5GHz band antenna, a WIFI antenna, etc. with a frequency greater than 2GHz, the resistance at the position of the connector 3 in the embodiment of the present application is small, and the loss of the RF operation can also be lower. The impedance fluctuation range at the position of the connector 3 is small (that is, the impedance difference at different points is small), and the frequency deviation of the RF operation can also be reduced.

[0102] Table 1

[0103] Test Points Impedance(Ω) Test point 1 0.04 Test point 2 0.07 Test point 3 0.03 Test point 4 0.03 Test point 5 0.06 Test point 6 0.07 Test point 7 0.01 Test point 8 0.02 Test point 9 0.02 Test point 10 0.02

[0104] At the same time, in the middle frame 20 provided in the embodiment of the present application, the outer frame 2 and the connector 3 are connected by welding. Compared with the case where the middle plate and the outer frame are directly connected by rivets, the stress at the connection position of the connector 3 and the outer frame 2 can be smaller, and the stress at the connection position of the middle plate 1 and the outer frame 2 can be smaller, so that the middle frame 20 is not easy to be twisted and deformed, and the flatness of the middle frame 20 is effectively improved. Compared with the case where the middle plate and the outer frame are connected by riveting without rivets, the thickness of the connection between the middle plate 1 and the outer frame 2 provided in the embodiment of the present application can be smaller, which is conducive to reducing the thickness of the middle frame 20, reducing the thickness of the electronic device 100 using the middle frame 20, and realizing an ultra-thin electronic device 100.

[0105] In some embodiments, see Figure 2 to Figure 4 The outer frame 2 may further include an antenna slot 23, and the middle frame 20 may further include a filling portion 4, which is located in the antenna slot 23 and made of an insulating material. The antenna slot 23 may divide the outer frame 2 into a plurality of parts, and the filling portion 4 is located in the antenna slot 23 to insulate two adjacent parts, and the plurality of parts may be used as different antennas respectively.

[0106] The "different antennas" mentioned here may be, for example, a main antenna, a WIFI antenna, a Bluetooth antenna, etc. The embodiment of the present application does not specifically limit the type of antenna.

[0107] Exemplarily, the material of the filling part 4 may be a thermosetting or thermoplastic material, such as plastic, resin, etc.

[0108] When multiple parts of the outer frame 2 are used as antennas, the outer frame 2 includes multiple feeding points, which are electrically connected to the middle plate 1 at the feeding points, and other positions of the outer frame 2 except the feeding points are insulated from the middle plate 1. In the embodiment of the present application, there is no restriction on the number of feeding points in the outer frame 2 and the positions of the feeding points, as long as the antenna can be electrically connected to the middle plate 1.

[0109] Figure 5 , Fig. 6A and Figure 6B It can be three possible cross-sectional schematic diagrams of the connection between the feed point in the outer frame 2 and the middle plate 1. Figure 5 As shown, the filling portion 4 may not extend between the feed point and the middle plate 1. Alternatively, as Fig. 6A and Figure 6B As shown, in the direction X parallel to the middle plate 1 , the filling portion 4 can also extend to between the extending portion 22 and the middle plate 1 , but the filling portion 4 does not affect the signal transmission between the feeding point and the middle plate 1 .

[0110] At other positions of the outer frame 2 except the feeding point, such as Figure 6C As shown, the filling portion 4 can extend into the extension portion 22 of the outer frame 2. The sum of the thickness d3 of the portion of the middle plate 1 in contact with the extension portion 22 and the thickness d1 of the extension portion 22 is less than or equal to the thickness d4 of the filling portion 4. The filling portion 4 is used to separate the portion of the extension portion 22 connected to the main body 21 and the portion of the extension portion 22 connected to the middle plate 1, so that the outer frame 2 and the middle plate 1 are insulated.

[0111] In some embodiments, Figure 6C As shown, the mounting hole 11 may be a through hole. In other embodiments, such as Fig. 7A and Figure 7B As shown, the mounting hole 11 may be a blind hole.

[0112] When the middle plate 1 includes a plurality of mounting holes 11, the plurality of mounting holes 11 may all be through holes, or the plurality of mounting holes 11 may all be blind holes, or a portion of the plurality of mounting holes 11 may be through holes and another portion may be blind holes.

[0113] When the mounting hole 11 is a blind hole, Fig. 7A As shown, the mounting hole 11 may be located on a side of the middle plate 1 away from the extension portion 22. Alternatively, as shown in FIG. Figure 7B As shown, the mounting hole 11 may also be located on a side of the middle plate 1 close to the extension portion 22 .

[0114] In some embodiments, the material of the connector 3 can be the same as that of the outer frame 2. In this way, the melting point of the connector 3 and the melting point of the outer frame 2 can be the same. When welding the connector 3 and the outer frame 2, it is not easy to affect the yield of the welding point between the connector and the outer frame 2 due to the large difference between the melting points of the connector 3 and the outer frame 2, which is conducive to further improving the connection strength between the connector 3 and the outer frame 2 and improving the connection stability between the connector 3 and the outer frame 2.

[0115] In some examples, the shear strength of the weld between the extension 22 and the connector 3 is greater than or equal to 100 N, and the pull strength of the weld between the extension 22 and the connector 3 is greater than or equal to 90 N. In this way, the connection stability between the extension 22 and the connector 3 is better, the connection stability between the outer frame 2 and the middle plate 1 and the connector 3 is better, the stability of the middle frame 20 can be higher, and the impact resistance of the middle frame 20 can also be better, which is conducive to improving the service life of the electronic device 100.

[0116] See also Figure 2 , Figure 5 and Fig. 7A In some embodiments, the connecting member 3 may include a first connecting portion 31 and a second connecting portion 32 that are perpendicular to each other, the first connecting portion 31 is located in the mounting hole 11 and is welded to the extension portion 22, and part of the middle plate 1 is located between the second connecting portion 32 and the extension portion 22.

[0117] In this way, on the one hand, the middle plate 1 is confined between the second connection part 32 of the connector 3 and the extension part 22 of the outer frame 2. In the thickness direction Z of the middle plate 1 and in the direction X parallel to the middle plate 1, relative displacement is not easy to occur between the middle plate 1 and the connector 3, and the middle plate 1 and the connector 3 are not easy to separate. On the other hand, the first connection part 31 and the second connection part 32 of the connector 3 are in contact with the middle plate 1, and the contact area between the middle plate 1 and the connector 3 can also be increased. The connection stability between the middle plate 1, the outer frame 2 and the connector 3 can be good, which is conducive to further improving the yield of the middle frame 20 and improving the use stability of the middle frame 20.

[0118] It is understandable that if Fig. 7AAs shown, when the mounting hole 11 is a blind hole and the blind hole is located on the side of the middle plate 1 away from the extension 22, the connector 3 is welded not only to the outer frame 2 but also to the middle plate 1. However, compared with the solution of direct welding of the middle plate 1 and the outer frame 2, the thickness of the middle plate 1 between the first connection part 31 and the outer frame 2 is smaller, the material of the middle plate 1 at the welding point between the first connection part 31 and the outer frame 2 is less, and the material of the middle plate 1 has less influence on the performance of the welding point formed between the first connection part 31 and the extension 22, thereby improving the problem of welding defects at the welding position of the middle plate and the outer frame due to the low melting point and easy evaporation of magnesium alloy or magnesium-based composite material, high activity and easy oxidation, or due to the presence of a large number of pores in the die-cast aluminum material when the middle plate and the outer frame are directly welded together, so that the connection reliability between the middle plate 1 and the outer frame 2 can be higher, which is conducive to improving the stability of the middle frame 20, improving the impact resistance of the middle frame 20, and ensuring the consistency of the radio frequency performance of the frame antenna in the electronic device 100.

[0119] In some examples, such as Figure 5 As shown, the first connection portion 31 is located inside the mounting hole 11 , and the second connection portion 32 may be located outside the mounting hole 11 . At this time, the end surface 321 of the second connection portion 32 connected to the first connection portion 31 may contact the surface S1 of the middle plate 1 away from the extension portion 22 .

[0120] Figure 8 for Figure 3 Another cross-sectional schematic diagram of the middle frame 20 at the BB' position is shown. Figure 8 In other examples, the mounting hole 11 is a stepped hole, and the first connection portion 31 and the second connection portion 32 are both located in the stepped hole. At this time, the end surface 322 of the second connection portion 32 away from the first connection portion 31 is flush with the surface S1 of the middle plate 1 away from the extension portion 22. In this way, the flatness of the middle frame 20 can be higher, so that the middle frame 20 can better carry electronic components or display screens, and improve the yield rate of the electronic device 100 using the middle frame 20.

[0121] In some examples, the connector 3 may be a flat head rivet. The rivet head of the flat head rivet corresponds to the second connecting portion 32, and the rivet rod of the flat head rivet corresponds to the first connecting portion 31. When the connector 3 is a flat head rivet, the end surface of the second connecting portion 32 away from the first connecting portion 31 is a plane, which is conducive to improving the surface flatness of the middle plate 1 on which the connector 3 is installed.

[0122] Continue reading Figure 7B In other embodiments, the connecting member 3 is a column, and the connecting member 3 is interference-fitted with the mounting hole 11. In this way, the connecting member 3 has a simple structure and is easy to obtain, which is conducive to simplifying the structure of the middle frame 20.

[0123] It is understandable that in order to improve the flatness of the middle frame 20 , when the connecting member 3 is a column, the surface of the connecting member 3 can be flush with the surface of the middle plate 1 close to the extension portion 22 or the surface of the middle plate 1 away from the extension portion 22 .

[0124] In some embodiments, Fig. 9A and Fig. 9B As shown, the extension portion 22 includes a first portion 221 and a second portion 222, the second portion 222 is arranged around the first portion 221, and a molten pool R is provided between the first portion 221 and the connector 3. In the embodiment of the present application, the depth and width of the molten pool R are not limited and can be designed according to actual needs.

[0125] Fig.10 This is a physical picture of the middle frame 20 provided in the embodiment of the present application at the welding point between the extension part 22 and the connecting member 3, wherein the material of the extension part 22 is aluminum alloy, and the material of the connecting member 3 is titanium. Fig.10 As shown, since the diffusion capacity of the material of the connector 3 (titanium) is greater than the diffusion capacity of the material of the extension portion 22 (aluminum alloy), the material of the connector 3 extends from the interface where the connector 3 and the extension portion 22 contact into the extension portion 22 .

[0126] Fig.11 This is a diagram showing the element detection results of the middle frame 20 provided in the embodiment of the present application at the welding point between the extension portion 22 and the connector 3. Fig.11 As shown, in the molten pool R, the element (Al) of the outer frame 2 can pass through the interface between the extension portion 22 and the connector 3 and diffuse into the connector 3. The element (Ti) of the connector 3 can pass through the interface between the extension portion 22 and the connector 3 and diffuse into the extension portion 22.

[0127] Fig.12 Another physical picture of the extension part 22 provided in the embodiment of the present application at the welding point between the outer frame 2 and the connecting member 3, wherein the material of the extension part 22 is the same as that of the connecting member 3, both of which are titanium. Fig.12 As shown, in the molten pool R, the material of the extension portion 22 and the material of the connecting member 3 are remelted after welding, and obvious crystal bonds are formed between atoms.

[0128] In some examples, such as Fig. 9A As shown, the molten pool R may extend from the first portion 221 away from the surface S2 of the middle plate 1 toward the connecting member 3 .

[0129] In other examples, such as Fig. 9B As shown, the molten pool R may extend from a surface S3 of the connector 3 away from the extension portion 22 into the first portion 221 .

[0130] In some embodiments, see Fig. 9A , Fig. 9B and Fig.13 The main body 21 includes a first surface 211 and a second surface 212 opposite to each other, and a first side surface 213 and a second side surface 214 connecting the first surface 211 and the second surface 212. The first surface 211 is farther away from the extension portion 22 than the second surface 212, and the second surface 212 is connected to the extension portion 22.

[0131] For example, Fig. 9A , Fig. 9B and Fig.13 As shown, the first surface 211 can be a curved surface. In this way, different positions of the first surface 211 can have the same mechanical strength, and compared with the solution where the first surface 211 is a plane, the first surface 211 is a curved surface, which can also make the outer frame 2 use less material, thereby helping to reduce the weight of the outer frame 2. At the same time, the first surface 211 is a curved surface, which can also make the surface of the outer frame 2 smooth, thereby preventing the outer frame from scratching other structures of the electronic device or the user, which is conducive to improving the user experience of the electronic device 100 using the middle frame 20.

[0132] In some embodiments, Fig. 9A , Fig. 9B and Fig.13 As shown, the middle frame 20 further includes a decoration layer 5 , and the decoration layer 5 at least covers the first surface 211 .

[0133] Wherein, when the material of the outer frame 2 includes aluminum alloy, the decorative layer 5 can be formed by an anodizing process, and the material of the decorative layer 5 can include aluminum oxide. When the material of the outer frame 2 includes one of a titanium-based material, an iron-based material, a titanium-aluminum composite material, and a steel-aluminum composite material, the decorative layer 5 can be formed by a physical vapor deposition process, and the material of the decorative layer 5 can include, for example, titanium nitride, or other nitrogen- or carbon-containing film layers. In the embodiment of the present application, there is no limitation on the thickness of the decorative layer 5, as long as it can protect the outer frame 2.

[0134] The embodiment of the present application provides a decorative layer 5, which can, on the one hand, color the surface of the outer frame 2, improve the appearance of the outer frame 2, and increase users' preference for the electronic device 100; on the other hand, the decorative layer 5 can also be used to protect the outer frame 2 to prevent the outer frame 2 from being corroded by water vapor and oxygen in the environment.

[0135] In some examples, such as Fig. 9A As shown, the molten pool R extends from the surface S2 of the first portion 221 away from the middle plate 1 to the connecting member 3. At this time, in addition to the first surface 211, the decorative layer 5 can also cover the surface of the second portion 222 away from the middle plate 1, the first side surface 213, the second side surface 214, and the portion of the second surface 212 that is not in contact with the extension portion 22. That is, the decorative layer 5 covers the surface of the main body 21 and the surface of the second portion 222 of the extension portion 22 away from the middle plate 1.

[0136] In the middle frame 20 provided in the embodiment of the present application, in addition to the first surface 211, the decorative layer 5 also covers the surface of the second part 222 away from the middle plate 1, the first side surface 213, the second side surface 214, and the part of the second surface 212 that is not in contact with the extension 22. On the one hand, the decorative layer 5 can be used to protect the second part 222 of the extension 22 and the main body 21, so that the second part 22 and the main body 21 are not easily corroded by water vapor and oxygen in the external environment. On the other hand, the decorative layer 5 can be used to enhance the appearance of the second part 222 and the main body 21, so that the second part 222 and the main body 21 can have rich colors, so that the middle frame 20 provided by the embodiment of the present application can have a better appearance, and improve the appearance of the electronic device 100 using the middle frame 20.

[0137] When the molten pool R extends from the surface S2 of the first portion 221 away from the middle plate 1 to the connector 3, the decorative layer 5 exposes the surface of the first portion 221 away from the connector 3 and the surface of the first portion 221 close to the connector 3, which helps to avoid affecting the welding yield due to the high melting point of the decorative layer 5.

[0138] In other examples, such as Fig. 9B As shown, the molten pool R extends from the surface of the connector 3 away from the extension portion 22 to the inside of the first portion 221. At this time, in addition to the first surface 211, the decorative layer 5 also covers the surface of the first portion 221 away from the middle plate 1, the surface of the second portion 222 away from the middle plate 1, the first side surface 213, the second side surface 214, and the portion of the second surface 212 that is not in contact with the extension portion 22. That is, the decorative layer 5 covers the remaining surfaces of the outer frame 2 except the surface of the first portion 221 close to the connector 3 and the surface of the second portion 222 close to the middle plate 1.

[0139] In the embodiment of the present application, in addition to the first surface 211, the decorative layer 5 also covers the surface of the first part 221 away from the middle plate 1, the surface of the second part 222 away from the middle plate 1, the first side surface 213, the second side surface 214, and the part of the second surface 212 that is not in contact with the extension 22. On the one hand, the decorative layer 5 can be used to protect the extension 22 and the main body 21, so that the extension 22 and the main body 21 are not easily corroded by water vapor and oxygen in the external environment. On the other hand, the decorative layer 5 can be used to enhance the appearance of the main body 21 and the extension 22, so that the main body 21 and the extension 22 can have rich colors, so that the middle frame 20 provided by the embodiment of the present application can have a better appearance, and improve the appearance of the electronic device 100 using the middle frame 20.

[0140] When the molten pool R extends from the surface of the connector 3 away from the extension portion 22 to the first portion 221 , the decorative layer 5 exposes the surface of the first portion 221 close to the connector 3 , which helps to avoid affecting the welding yield due to the high melting point of the decorative layer 5 .

[0141] In some other examples, such as Fig.13 and Fig.14 As shown, the decoration layer 5 may only cover the first surface 211. In this way, during the welding process of the connector 3 and the extension 22, the decoration layer 5 is not likely to cause adverse effects on the welding point between the extension 22 and the connector 3. At the same time, the decoration layer 5 is set to have a smaller coverage area, thereby improving the appearance of the main body 21 and the middle frame 20 while reducing the manufacturing cost of the middle frame 20.

[0142] In some examples, such as Fig.14 As shown, the material of the outer frame 2 includes a titanium-aluminum composite material, the main body 21 includes a first sublayer 21a and a second sublayer 21b, the first sublayer 21a is farther away from the extension portion 22 than the second sublayer 21b, the second sublayer 21b is connected to the extension portion 21, the material of the first sublayer 21a includes titanium, and the material of the second sublayer 21b and the material of the extension portion 22 both include aluminum alloy.

[0143] In the outer frame 2 provided in the embodiment of the present application, the material of the first sublayer 21a of the main body 21 is set to titanium metal, the material of the second sublayer 21b is set to aluminum alloy, and the material of the extension part 22 is set to aluminum alloy. The density of aluminum alloy is lower than that of titanium metal, so that the middle frame 20 can have a metallic texture and appearance effect while having a smaller weight, which is beneficial to reduce the preparation cost of the middle frame 20.

[0144] For other examples, see Fig.14 The material of the outer frame 2 includes a steel-aluminum composite material, the main body 21 includes a third sublayer 21c and a fourth sublayer 21d, the third sublayer 21c is farther away from the extension portion 22 than the fourth sublayer 21d, the fourth sublayer 21d is connected to the extension portion 22, the material of the third sublayer 21c includes stainless steel, and the material of the fourth sublayer 21d and the material of the extension portion 22 both include aluminum alloy.

[0145] In the outer frame 2 provided in the embodiment of the present application, the material of the first sublayer 21a of the main body 21 is set to stainless steel, the material of the second sublayer 21b is set to aluminum alloy, and the material of the extension part 22 is set to aluminum alloy. The density of aluminum alloy is lower than that of stainless steel, so that the middle frame 20 can have a metallic texture and appearance while having a smaller weight, which is beneficial to reduce the preparation cost of the middle frame 20.

[0146] like Fig.15As shown, an embodiment of the present application provides a method for preparing a middle frame, and the method includes steps S100 to S400.

[0147] S100, see Figure 2 and Figure 5 , providing a middle plate 1, an outer frame 2 and a connecting member 3. The outer frame 2 includes a main body 21 and an extension 22 connected to each other, and the thickness of the extension 22 is less than the thickness of the main body 21.

[0148] For example, the middle plate 1 can be prepared by a die-casting process or a semi-solid die-casting process, and the material of the middle plate can include but is not limited to die-cast magnesium alloys AZ91D, AM6, etc. Alternatively, the middle plate 1 can also be obtained by stamping or cutting, and the material of the middle plate 1 can include but is not limited to AZ31, AZ80, AZ91D, ZK61, magnesium-based composite materials, etc.

[0149] In some examples, the material of the outer frame 2 includes aluminum alloy. In this case, the outer frame 2 can be obtained by a stamping process or a CNC processing method.

[0150] In other examples, the material of the outer frame 2 includes titanium-based materials, iron-based materials, titanium-aluminum composite materials, and steel-aluminum composite materials. In this case, if the raw material of the outer frame is in the shape of a strip, the raw material can be processed by bending and forging to obtain the outer frame 2. If the raw material of the outer frame is in the shape of a plate, the outer frame 2 can be obtained by stamping and cutting.

[0151] S200 , installing the connecting member 3 on the middle plate 1 . The connecting member 3 is located in the mounting hole 11 of the middle plate 1 .

[0152] In some examples, the mounting hole 11 may be formed during the preparation of the middle plate 1. In other examples, the mounting hole 11 may be formed during the installation of the connector 3 on the middle plate 1. This application does not limit this.

[0153] In some examples, after the connector 3 is installed on the middle plate 1 , the middle plate 1 and the connector 3 may be subjected to a film passivation treatment, thereby forming an oxide layer on the middle plate 1 and the connector 3 to protect the middle plate 1 and the connector 3 .

[0154] S300, fix the middle plate 1 and the outer frame 2. The outer frame 2 is located outside the middle plate 1, the extension part 22 is located on the side of the main body 21 facing the middle plate 1, and the extension part 22 is stacked with the middle plate 1. Exemplarily, a clamp can be used to fix the middle plate 1 and the outer frame 2.

[0155] S400 , welding the extension portion 22 to the connecting member 3 .

[0156] The material of the middle plate 1 includes one of magnesium alloy, magnesium-based composite material and aluminum alloy, and the material of the outer frame 2 includes one of aluminum alloy, titanium-based material, iron-based material, titanium-aluminum composite material and steel-aluminum composite material. The microhardness of the connecting member 3 is greater than that of the middle plate 1.

[0157] The beneficial effects that can be achieved by the preparation method provided in the embodiment of the present application are the same as the technical effects that can be achieved by the middle frame 20 provided in the above-mentioned embodiment of the present application, and the present application will not repeat them here.

[0158] In some embodiments, Fig.16 As shown, step S400 may include step S410.

[0159] S410, such as Fig.17 and Fig.18 As shown, the extension portion 22 and the connecting member 3 are welded by a laser welding process.

[0160] At this point, in some examples, such as Fig.17 As shown, the laser can be irradiated toward the connecting member 3 from the side of the extension portion 22 away from the connecting member 3. In other examples, such as Fig.18 As shown, the laser can be irradiated toward the extension portion 22 from a side of the connecting member 3 away from the extension portion 22 .

[0161] In the embodiments of the present application, there is no restriction on parameters such as laser welding time and laser intensity, and they can be designed according to actual needs.

[0162] In the embodiment of the present application, the extension part 22 and the connection part 3 are welded by a laser welding process, the welding precision can be high, the deformation of the extension part 22 and the connection part 3 can be small, the stress between the extension part 22 and the connection part 3 can be small, and after the extension part 22 and the connection part 3 are welded, the middle frame 20 is not easy to deform, which is conducive to improving the flatness of the middle frame 20. At the same time, the welding speed of laser welding is high, and the use of the laser welding process to weld the extension part 22 and the connection part 3 is also conducive to improving the preparation speed of the middle frame 20 and improving the preparation efficiency of the middle frame 20.

[0163] In some embodiments, the material of the outer frame 2 includes aluminum alloy. Fig.19 As shown, the preparation method further includes step S500.

[0164] S500 , forming a decorative layer 5 by adopting anodizing process.

[0165] In other embodiments, the material of the outer frame 2 includes one of a titanium-based material, an iron-based material, a titanium-aluminum composite material, and a steel-aluminum composite material. Fig. 20 As shown, the preparation method further includes step S600.

[0166] S600 , forming a decoration layer 5 by adopting a physical vapor deposition process.

[0167] See also Fig.13 The main body 21 includes a first surface 211 and a second surface 212 opposite to each other, and a first side surface 213 and a second side surface 214 connecting the first surface 211 and the second surface 212. The first surface 211 is farther away from the middle plate 1 than the second surface 212, and the second surface 212 is connected to the extension portion 22. The decorative layer 5 at least covers the first surface 211. Fig.19 and Fig. 20 As shown, the decoration layer 5 may be formed before step S400 .

[0168] In some examples, the outer frame 2 may be ground and polished before forming the decorative layer 5. The surface roughness of the outer frame 2 may be reduced by grinding and polishing to prevent the outer frame 2 from being too rough and affecting other structures of the electronic device.

[0169] The embodiment of the present application can color the surface of the outer frame 2 by setting the decorative layer 5, thereby improving the appearance of the outer frame 2 and increasing the user's preference for the electronic device 100. On the other hand, the decorative layer 5 can also be used to protect the outer frame 2 to prevent the outer frame 2 from being corroded by water vapor and oxygen in the environment.

[0170] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0171] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A middle frame, characterized in that: include: A middle plate (1) comprising a mounting hole (11); an outer frame (2) located on the outer side of the middle plate (1); the outer frame (2) comprises a main body (21) and an extension (22) connected to each other, the extension (22) being located on a side of the main body (21) facing the middle plate (1), and the thickness of the extension (22) being smaller than the thickness of the main body (21); the extension (22) and the middle plate (1) being stacked; A connecting piece (3) is located in the mounting hole (11) and is connected to the middle plate (1); the connecting piece (3) is welded to the extension portion (22); The material of the middle plate (1) includes one of a magnesium alloy, a magnesium-based composite material and an aluminum alloy; the material of the outer frame (2) includes one of an aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material; and the microhardness of the connecting piece (3) is greater than the microhardness of the middle plate (1).

2. The middle frame according to claim 1, characterized in that: The connecting member (3) comprises a first connecting portion (31) and a second connecting portion (32) which are perpendicular to each other, the first connecting portion (31) being located in the mounting hole (11) and welded to the extending portion (22), and a portion of the middle plate (1) being located between the second connecting portion (32) and the extending portion (22).

3. The middle frame according to claim 2, characterized in that: The mounting hole (11) is a stepped hole, and the first connecting portion (31) and the second connecting portion (32) are both located in the stepped hole; the end surface of the second connecting portion (32) away from the first connecting portion (31) is flush with the surface of the middle plate (1) away from the extension portion (22).

4. The middle frame according to claim 1, characterized in that: The connecting piece (3) is a column, and the connecting piece (3) and the mounting hole (11) are interference fit.

5. The middle frame according to any one of claims 1 to 4, characterized in that: The material of the connecting piece (3) is the same as that of the outer frame (2).

6. The middle frame according to any one of claims 1 to 5, characterized in that: The mounting hole (11) comprises a through hole or a blind hole.

7. The middle frame according to any one of claims 1 to 6, characterized in that: The extension portion (22) comprises a first portion (221) and a second portion (222), wherein the second portion (222) is arranged around the first portion (221), and the first portion (221) and the connecting member (3) have a molten pool (R), and the molten pool (R) extends from the surface of the first portion (221) away from the middle plate (1) to the connecting member (3); or, the molten pool (R) extends from the surface of the connecting member (3) away from the extension portion (22) to the first portion (221).

8. The middle frame according to any one of claims 1 to 7, characterized in that: The main body (21) comprises a first surface (211) and a second surface (212) which are opposite to each other, and a first side surface (213) and a second side surface (214) which connect the first surface (211) and the second surface (212), wherein the first surface (211) is farther away from the extension portion (22) than the second surface (212), and the second surface (212) is connected to the extension portion (22); The middle frame (20) further comprises a decorative layer (5), wherein the decorative layer (5) at least covers the first surface (211).

9. The middle frame according to claim 8, characterized in that: The molten pool (R) extends from the surface of the first part (221) away from the middle plate (1) toward the connecting piece (3), and the decorative layer (5) also covers the surface of the second part (222) away from the middle plate (1), the first side surface (213), the second side surface (214), and a portion of the second surface (212) that is not in contact with the extension portion (22).

10. The middle frame according to claim 8, characterized in that: The molten pool (R) extends from the surface of the connecting member (3) away from the extension portion (22) into the first portion (221); the decorative layer (5) also covers the surface of the first portion (221) away from the middle plate (1), the surface of the second portion (222) away from the middle plate (1), the first side surface, the second side surface, and a portion of the second surface (212) that is not in contact with the extension portion (22).

11. The middle frame according to any one of claims 1 to 10, characterized in that: The shear strength of the weld between the extension part (22) and the connection piece (3) is greater than or equal to 100N, and the pull-out strength of the weld between the extension part (22) and the connection piece (3) is greater than or equal to 90N.

12. The middle frame according to any one of claims 1 to 11, characterized in that: The material of the outer frame (2) comprises a titanium-aluminum composite material, the main body (21) comprises a first sublayer (21a) and a second sublayer (21b), the first sublayer (21a) is farther away from the extension part (22) than the second sublayer (21b), the second sublayer (21b) is connected to the extension part (22), the material of the first sublayer (21a) comprises titanium, and the material of the second sublayer (21b) and the material of the extension part (22) both comprise an aluminum alloy; or, The material of the outer frame (2) comprises a steel-aluminum composite material, the main body (21) comprises a third sublayer (21c) and a fourth sublayer (21d), the third sublayer (21c) is farther away from the extension part (22) than the fourth sublayer (21d), the fourth sublayer (21d) is connected to the extension part (22), the material of the third sublayer (21c) comprises stainless steel, and the material of the fourth sublayer (21d) and the material of the extension part (22) both comprise aluminum alloy.

13. A method for preparing a middle frame, characterized in that: include: A middle plate (1), an outer frame (2) and a connecting piece (3) are provided; the outer frame (2) comprises a main body (21) and an extension (22) which are connected to each other, and the thickness of the extension (22) is smaller than the thickness of the main body (21); The connecting piece (3) is mounted on the middle plate (1); the connecting piece (3) is located in the mounting hole (11) of the middle plate (1); The middle plate (1) and the outer frame (2) are fixed; the outer frame (2) is located on the outer side of the middle plate (1), the extension portion (22) is located on the side of the main body (21) facing the middle plate (1), and the extension portion (22) and the middle plate (1) are stacked; Welding the extension portion (22) to the connecting member (3); The material of the middle plate (1) includes one of a magnesium alloy, a magnesium-based composite material and an aluminum alloy, and the material of the outer frame (2) includes one of an aluminum alloy, a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material; the microhardness of the connecting piece (3) is greater than the microhardness of the middle plate (1).

14. The preparation method according to claim 13, characterized in that: The welding of the extension portion (22) and the connection piece (3) comprises: welding the extension portion (22) and the connection piece (3) using a laser welding process.

15. The preparation method according to claim 13 or 14, characterized in that: The material of the outer frame (2) includes aluminum alloy, and the preparation method further includes: forming the decorative layer (5) by anodizing; or, The material of the outer frame (2) comprises one of a titanium-based material, an iron-based material, a titanium-aluminum composite material and a steel-aluminum composite material, and the preparation method further comprises: forming a decorative layer (5) by a physical vapor deposition process; The main body (21) comprises a first surface (211) and a second surface (212) that are opposite to each other, and a first side surface and a second side surface connecting the first surface and the second surface, the first surface (211) being farther away from the middle plate (1) than the second surface (212), and the second surface (212) being connected to the extension portion (22); and the decorative layer (5) at least covers the first surface (211).

16. An electronic device, characterized in that: include: display screen (10) and rear housing (30), The middle frame (20) according to any one of claims 1 to 12, wherein the middle frame (20) is located between the display screen (10) and the rear housing (30); and the outer frame (2) of the middle frame (20) serves as a side of the electronic device (100).

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